Research Projects

The following projects are representative of the types of research projects assigned to CEE research assistants (RAs). Not all of the projects on this list will require an RA for the next term, and not all of the research projects in the department are listed, but the list does provide a good indication of the types of research RAs perform.

If you are a prospective or recently admitted student and you are interested in a project, please contact the faculty member directly to get more information about his/her available research projects or visit that faculty member's website to learn more.

Environmental Chemistry
Environmental Fluid Mechanics and Coastal Engineering
Environmental Microbiology
Geotechnical Engineering, Geomechanics and Geotechnology
Hydrology and Hydroclimatology
Infrastructure Systems
Mechanics of Materials and Structures
Transportation Systems

Environmental Chemistry

Professor Philip Gschwend
Demonstrating LDPE Passive Samplers for Assessing Contaminated Sediments

The overall objective is to demonstrate that the polyethylene (PE) passive sampling methodology is a commercially viable technology for determining horizontal and vertical distributions of chemicals like PCBs and PAHs in sediments. To this end, our specific objectives include: (a) demonstrating the accuracy of the PE passive sampling method used in the field (i.e., in situ), (b) demonstrating the advantages of using PE passive sampling for defining the horizontal and vertical extent of contamination, (c) showing the PE passive sampling is well suited to long term monitoring programs (LTM), and (d) establishing not only the performance capabilities (limits of detection, accuracy, precision), but also the cost benefits of this passive sampling approach as compared to traditional sampling and analysis methods.

Professor Philip Gschwend
Estimating Black Carbon-Water Sorption Coefficients of Organic Contaminants in Sediments

In order to improve our fundamental understandings of chemical sorption to real world sediments, we need to elucidate the role of black carbon(s) (e.g., soots, chars, coal dust) in these deposits. Such BC sorption greatly reduces the bioavailability of a wide range of organic contaminants. This improved understanding will have a several important impacts including: (a) improved understanding and modeling of bioavailability when site managers are using sediment concentration data, (b) enhanced means to use and interpret passive samplers when assessing wide arrays of target compounds using only a few performance reference compounds, (c) insights to kinetic limitations associated with phenomena like contaminant desorption from resuspended sediments, (d) an ability to pre-judge the sorption of a far more diverse array of organic contaminants and (e) more accurate expectations for risk reduction associated with remedial efforts since BC sorption exhibits nonlinear behavior.

Professor Philip Gschwend
Application of Passive Sampler Technology to Assess DDTs and Dieldrin Release From Superfund Site Sediments Before, During and After Remediation Activities

Our objectives are (a) to utilize and compare two passive sampler technologies, polyethylene devices (PEDs) and solid phase micro-extraction fibers (SPME), for monitoring the presence of DDTs and dieldrin emanating from contaminated soils and sediments into the waters of the Lauritzen Channel-Richmond Harbor-San Francisco Bay before, during, and after environmental remediation of the United Heckathorn site, and (b) to compare DDTs and dieldrin uptake by the passive samplers to bioaccumulation seen (by us) in field deployments using a bivalve and in laboratory tests using a bivalve and an amphipod and to fish collected in the area (as reported by others).

Professor Philip Gschwend
A General Methodology for Evaluating Bed Sediments for Narcosis Toxicity
The objective of this project is to develop an accurate means with which to analyze the narcosis toxicity due to mixtures of hydrophobic organic compounds in sediments. Mixtures of toxic organic compounds can be accumulated from sediments in passive samplers such as those made of polyethylene. We are using two-dimensional gas chromatography with flame ionization detection analyses to, not only quantifying the components of these mixes, but also to provide the necessary weighting information needed to calculate phospholipid-normalized body burdens for organisms equilibrated within the original sediments.

Associate Professor Colette L. Heald
Satellite-based Investigations of Atmospheric Composition

Space-based observations provide large-scale and continuous insight into the emissions and transport of atmospherically relevant trace gases and particles. These observations are key to investigating the evolution of the atmosphere, particularly over poorly observed regions (e.g. the remote oceans). Research in our group addresses two primary topics: (1) the Intercontinental Transport of Pollution and (2) Using Remote Observations to Improve Emission Estimates. Graduate student research can be designed to address aspects of these topics.  

Associate Professor Colette L. Heald
Investigating Atmospheric Aerosol Sources, Composition and Chemistry

Aerosols are particles suspended in the atmosphere. They have both natural (e.g. dust and volcanic) and anthropogenic (e.g. vehicle emissions, industrial) sources and through their interaction with radiation can affect climate. Aerosols can also be a component of urban smog and contribute to visibility degradation. Understanding the sources, formation and transformation of aerosols in the troposphere is key to characterizing their role in climate and air pollution. Work in our group focuses on understanding the global budgets of aerosols in the atmosphere: What are their sources? How are they processed in the atmosphere? And what impact do they have? We make use of modeling and observational analysis (including the interpretation of satellite observations) to answer these questions.  

 Upcoming projects in the group will explore the following topics:

  • Investigating how the chemical transformations and mixing of black carbon (i.e. soot) in the atmosphere affect global radiative forcing.
  • Development of a new global model scheme to treat the chemical and physical transformations of organic aerosol in the atmosphere
  • Using new satellite observations and aircraft measurements to investigate the role of ammonia in particle formation in the United States.
  • Investigating composition and trends in tropical aerosols. 

Professor Harry Hemond
Real-Time In-situ AUV-Based Underwater Chemical Sensing

Capabilities for in-situ chemical sensing are increasingly necessary to obtain the improved spatiotemporal resolution essential to make advances in  the understanding and improvement of water quality. In-situ measurement also makes chemical information available quickly, allowing quick responses as necessary while obviating the need for costly sample preservation and transport. Deployment aboard AUVs (autonomous underwater vehicles), particularly in concert with underwater data networks, further multiplies the potential benefits of in-situ chemical measurement. This work builds on our invention of the cycloidal underwater mass spectrometer (such as used to monitor the recent Gulf oil spill) and now also includes research into optical sensors for nonvolatile compounds and electrochemical sensors for ionic measurement. Current collaborators include Dr. K. Ng at SMART and Prof. J. Sinfield at Purdue.

Professor Harry Hemond
Methane Geochemistry of Stratified Lakes

Freshwater lakes are believed to be significant, but poorly quantified, sources of the greenhouse gas methane to the atmosphere. Methane is also important to the ecology of lakes, influencing both the food web and the oxidation-reduction chemistry of the waters. Current work focuses on the process of ebullition, or bubbling, which is very poorly understood and is difficult to quantify on account of its patchy and intermittent nature. An improved understanding of the interactions of microbiological methane production and consumption with the physics of organic-rich lake sediments will also lead to better models of global methane cycling and potentially to possibilities for energy harvesting.  Current collaborators include Prof. R. Juanes and Dr. C. Ruppel.

Professor Harry Hemond
The Anthrobiogeochemical Cycle of Indium

Indium is an important metal whose production is increasing dramatically due to new uses in the rapidly growing electronics, photovoltaic, and LED industries. Increases of  its usage by one or more orders of magnitude within the next few years are very possible. Yet little is known about the natural or industrial cycling of indium, and toxicological data are incomplete.  The investigation of the environmental behavior of indium focuses on current and possible future releases of indium to both the air and water environment, with a focus on the magnitudes and the chemical forms of these fluxes. Improved understanding of the anthrobiogeochemical cycle of indium will allow informed decisions about its future use, handling, and disposal.

Professor Harry Hemond
Kilowatt-Scale Solar Thermal Power Plants

Small-scale solar thermal power systems are potentially advantageous in remote power generation applications, particularly where both thermal and electric power are required.  To date these systems have only been commercialized as large scale power plants where power cycle infrastructure is borrowed from existing conventional thermal plants.  Small scale power cycles for solar thermal plants are currently not commercially available.  The organic Rankine cycle (ORC) offers significant promise for small-scale solar power generation, as heat engines based on an ORC are appropriate for converting relatively low temperature (<300 degrees C) thermal energy to electric power.  This facilitates operating at modest temperatures using relatively low cost solar collectors such as the parabolic trough mirror. Costs are also addressed by using cycle designs based on the use of modifications of  low-cost mass-produced fluid components such as are available from the HVAC industry.  This project also involves collaboration with the student-led STG (Solar Turbine Group).

Associate Professor Jesse Kroll
Aging of Atmospheric Organic Species

We use our fixed-temperature, fixed-volume 7.5 m3 Teflon chamber to probe how oxidative "aging" affects the amounts and chemical composition of atmospheric organic aerosol. A particular focus of our work is the isolation of a single phase in which multigenerational aging occurs (in the gas phase, in aqueous aerosol, etc.), requiring the development of novel approaches for generating high level of oxidants within a given phase.

Associate Professor Jesse Kroll
Heterogeneous Oxidation of Organic Aerosol

In collaboration with Kevin Wilson (Lawrence Berkeley National Laboratory) and Doug Worsnop (Aerodyne Research) we carry out flow-tube studies aimed at understanding the oxidation of particle-phase organic compounds by gas-phase OH radicals. A major focus is how chemical structure and degree of oxidation influences whether an organic molecule will undergo functionalization (which generally lowers its vapor pressure) or fragmentation (which generally increases it). Chemistry is primarily monitored with aerosol mass spectrometry, using a range of novel vaporization and ionization approaches.

Associate Professor Jesse Kroll
Atmospheric Black Carbon: Chemistry and Optical Properties

The direct climate impacts - the absorption and scattering of light - of black carbon (soot) particles are thought to be impacted by atmospheric processing, though this is highly uncertain at present. Using flow-tube and chamber techniques to age black carbon (via heterogeneous oxidation and/or the addition of secondary aerosol coatings), combined with state-of-the-art measurements of the chemical and optical properties of the particles, we hope to better understand how the climate-relevant properties of these particles evolve during their atmospheric lifetimes. This work is done in collaboration with Colette Heald (MIT) and Paul Davidovits (Boston College).

Associate Professor Jesse Kroll
Photolytic Generation of Secondary Organic Aerosol

In this project we study the formation of secondary organic aerosol (SOA) via the direct generation of key radical intermediate species. Alkoxy radicals and alkylperoxy radicals are generated from the photolysis of precursors (alkyl nitrites and alkyl iodides, respectively), and particle-phase products of their reactions are examined using aerosol mass spectrometry. The advantage of this approach is that individual reaction pathways and oxidation generations can be probed, which is not possible in standard hydrocarbon + oxidant studies.

Associate Professor Jesse Kroll
Emissions of Low-volatility Gas-phase Organic Species

While organic compounds with high vapor pressures (VOCs) and those with low vapor pressures (organic aerosol) are now routinely measured in lab and field studies, gas-phase organic compounds with vapor pressures between the two extremes (semivolatile organic compunds and intermediate-volatility organic compounds) generally are not. Thus we have developed a new mass spectrometric instrument for quantifying and chemically characterizing such species as an ensemble. This has been deployed to the field (BEACHON and SOAS), and has also been used to characterize emissions from mobile sources (aircraft and diesel engines).

Environmental Fluid Mechanics and Coastal Engineering back to top back to top

Professor Ole Madsen
Surf Zone Hydrodynamics and Sediment Transport

Understanding processes in the surf zone, where waves are breaking or broken, is critically important to coastal engineering. The dissipation of wave energy through breaking results in a reduction of wave momentum (so-called "radiation stresses") and thereby in wave-induced currents (longshore and cross-shore currents). Breaking waves also give rise to turbulence in the water column and in the thin bottom boundary layer. The latter dislodges bottom sediments and make these available for transport by the wave-induced currents. In this project, we are working with a numerical model that is capable of predicting the characteristics of breaking and broken waves, the resulting wave-induced currents and the associated sediment transport. Research centers on the improvement and generalization of this surf zone model, all components of which are in need of improvement. For example, (1) waves are treated as simple periodic disturbances with a simple correction accounting for the effects of narrow-banded spectral waves; (2) the model predicts both longshore currents and sediment transport quite accurately, but only for alongshore uniform beaches; and (3) cross-shore currents are reasonably well-predicted but the associated cross-shore transport of sediment is not. This project falls within the purview of the Singapore-MIT Alliance for Research and Technology, so research assistants may have the chance to spend time working in Singapore.

Professor Ole Madsen
Development of a Large-Scale Sediment Transport Model

Large-scale numerical coastal and ocean circulation models do not resolve motion of the scale of wind-waves. Nevertheless, slowly varying currents experience an enhanced bottom frictional resistance due to interaction with short period wind-waves. This enhanced (so-called "apparent") roughness is the appropriate one to use in large-scale circulation models, and the development of an efficient way to incorporate the apparent roughness in circulation models is one goal of this research. Another is to explore the effect of short period wind-waves in the mechanics of sediment transport in coastal waters. The bottom shear stress associated with short period wind-waves dislodges bottom sediment and makes it available for transport by slowly varying currents, which in the absence of the wind-waves would have been incapable of dislodging a single sediment grain. Thus, the effect of wind-waves needs to be formulated, parameterized and incorporated in large-scale numerical ocean and coastal circulation models. This project falls within the purview of the Singapore-MIT Alliance for Research and Technology, so research assistants may have the chance to spend time working in Singapore.

Professor Ole Madsen
Fundamental Experimental Research on Wave-Current-Sediment Interaction

As part of the Singapore-MIT Alliance for Research and Technology's Center for Environmental Sensing and Modeling, a unique experimental facility for wave-current-sediment interaction will be designed, constructed and operated in the Hydraulics Laboratory at the National University of Singapore. This facility will be able to reproduce field scale wave motions (velocities >1.5 m/s, periods >10 s) and should be available for use by fall 2009. The new facility will be similar to the large oscillating wave tunnel facility in Delft, Netherlands, and researchers will be able to use it to investigate a variety of fundamental aspects of sediment-fluid interaction in wave-dominated coastal waters. Initial experiments (1) on the influence of bottom slope on sediment transport rates by waves alone; (2) on the movable roughness of wave-rippled beds; and (3) on sediment transport rates by asymmetric and/or skewed waves, representative of waves in the surf zone, may be conducted by a research assistant whose home department is Civil and Environmental Engineering at MIT.

Professor Heidi Nepf
Sediment Transport in Vegetated Channels
The most obvious impact of vegetation in river channels is an increase in flow resistance and a reduction in conveyance capacity, so that for many years vegetation has been removed from channels to accelerate the passage of peak flows. However, vegetation has a positive influence on water quality, e.g. by removing nutrients and producing oxygen in stagnant regions. By baffling the flow and reducing bed-stress, vegetation creates regions of sediment retention and enhances channel stability. Because of these positive impacts, researchers now advocate the restoration of channel vegetation. However, the design of sustainable restoration schemes requires an understanding of how the distribution and density of vegetation determines sediment transport and the tendency toward deposition or erosion. These two projects will use laboratory studies to describe the interaction between vegetation, water motion, and sediment transport.   

  1. In the co-evolution of vegetation and channel morphology, we need to understand how individual patches of vegetation grow spatially and eventually merge with other regions of vegetation. The goal would be to understand how the patch size, shape and spacing to other patches impacts the flow around and in between the patches, and in turn impacts the potential for the patches to grow or diminish.
     
  2. Vegetation changes the scale and intensity of near bed turbulence.  The change in turbulence structure is believed to change the potential for sediment transport, but the role of turbulence in sediment transport is still not well understood. Most previous models link sediment transport to the mean bed stress. In this study, you will observe how the presence of vegetation changes the mean bed stress, as well as the nature of near bed turbulence. The goal is to derive a new parameterization for sediment motion within regions of vegetation, and to determine the relative role of mean bed stress and near bed turbulence. 

Professor Heidi Nepf
Nutrient Uptake by Aquatic Vegetation
Seagrass and freshwater macrophytes enhance water quality by filtering nutrients from the water, reducing re-suspension, and producing oxygen in stagnant regions. The global impact of these ecosystem services has been valued at over one trillion dollars per year. Unlike terrestrial plants, which acquire nutrients through their roots, aquatic plants acquire nutrients through their leaves and blades from the surrounding water. The nutrient uptake controls the growth of the vegetation, as well as its potential impact on water quality. This project will use laboratory experiments to examine how the interaction of individual blades with current and waves impacts the uptake potential at the blade surface, with the goal of providing better predictions of the potential maximum uptake rate for different hydrodynamic conditions. These studies feed into the larger question of how the hydrodynamic conditions at a site impact the growth of plants, the potential for restoration success, and their potential impact on carbon sequestration and primary production. 

Environmental Microbiology back to top back to top

Professor Sallie W. Chisholm
Integrative Systems Biology
The marine cyanobacterium Prochlorococcus is the smallest and most abundant photosynthetic cell on the planet. The goal of our lab is to understand this single microbe from the genome to the global scale, thereby contributing to the field of integrative systems biology. Work centers on the following topics:

  • The origins, nature and ecological impacts of genomic diversity among Prochlorococcus
  • The role of extracellular vesicles produced by bacteria in marine ecosystems
  • The role of viruses in Prochlorococcus ecology
  • Interactions and co-evolution of Prochlorococcus with heterotrophic bacteria
  • The role of ecotypic variation in the dynamics and stability of the global Prochlorococcus population
  • The role of Prochlorococcus in ocean food webs and biogeochemistry

Lab members have latitude to design their own projects under this general umbrella. We use the tools of genomics, metagenomics, transcriptomics and proteomics, and we have a vast culture collection of Prochlorococcus and phage as well as the complete genome sequences of 45 Prochlorococcus strains. Regular sampling programs take place off Bermuda and Hawaii, and we participate in research cruises throughout the global oceans.

Professor Martin Polz
The Ecology and Evolution of Bacterial Populations in the Wild

Our principal model system is bacteria of the genus Vibrio co-occurring in the coastal ocean. These afford the opportunity to study a wide range of environmental adaptations since their lifestyles range from free-living to symbiotic and pathogenic. We are also studying the dynamics of microbial communities in the ocean environment in response to physical, chemical and biological factors, and how bacterial communities effect the degradation of marine algae.

Some of the main focus areas of research are:

  • The genomic diversity within and between ecologically differentiated populations
  • The temporal and spatial dynamics of populations
  • The diversity and role of extrachromosomal elements (plasmids, viruses) in horizontal gene transfer
  • Predation mediated by viruses
  • The diversity and range of social interactions

Researchers in the lab use a combination of ecological, genomic and molecular genetic tools. For example, we are in the process of sequencing ~1,000 genomes and many more plasmids and viruses. Graduate students and postdocs are generally free to choose their own projects as long as they fit in with the overall focus of the lab.

Associate Professor Roman Stocker
Phytoplankton in Flow
Phytoplankton are photosynthetic microorganisms that form the base of the marine food web. Many species swim using flexible flagella and can reach remarkable speeds (~ 1 mm/s) in relation to their small size (often 5-50 microns). Despite being much slower than ocean currents or turbulence, their motility can dramatically affect their spatial distribution: they are not purely at the mercy of the flow! Using a combination of millifluidic experiments and mathematical modeling, we have shown that their motility (biased by inherent asymmetries in their morphology through a process called gyrotaxis) can explain the occurrence of dramatic thin layers of high phytoplankton concentration, often observed in the ocean a few meters below the surface and thought to be precursors of red tides. We also discovered that turbulence results in strong, microscale patchiness in the distribution of phytoplankton, depending on how fast cells swim and how stable they are against overturning by the flow. In a related project, we found that the coupling of shape and flow could change light climate in the ocean and increase the optical backscattering of natural plankton assemblages, because of the preferential alignment of elongated plankton induced by fluid shear. Currently, we are learning more about phytoplankton’s swimming strategies by using digital holographic microscopy to obtain three-dimensional trajectories of individual cells.

Associate Professor Roman Stocker
Bacteria in Flow: Unexpected Interactions
Functional traits are attributes that influence the fitness of a species. We use microfluidic experiments, microscale visualization and mathematical modeling to study the interplay between bacterial functional traits, such as shape and motility, and flow, which is ubiquitous in bacterial habitats. For example, bacterial flagella are chiral (specifically: helical). We discovered that the coupling of chirality and shear leads to a preferentially oriented movement, bacterial rheotaxis, akin to that in fish but of a passive nature. Bacterial rheotaxis is characterized by a drift across streamlines that originates from the reorientation of the cell body due to a lift force acting on the chiral flagellum and could hamper the quest of nutrients by bacteria. We are currently performing extensive microfluidic experiments to better understand the rich interactions among bacterial motility and flow.

Associate Professor Roman Stocker
The Mechanics of Bacterial Flagella: Buckling at the Nanoscale
Micron-sized bacteria represent the smallest and most abundant life form on Earth. Strikingly, bacteria are motile despite their small size and understanding their swimming mechanics is both intriguing and important. Although bacterial motility has been studied for half a century, we recently discovered a new mechanism of reorientation, used broadly among marine bacteria, which all (95% of swimming species) have only a single flagellum, in contrast for example to E. coli. By combining video microscopy at up to 2000 frames/s, image analysis, and mechanical stability theory, we visualized the dynamics of the cell and its flagellum as it changes swimming direction and discovered that the mechanism that allows them to reorient is a buckling instability of their flagellum. This project revealed an unexpected role of flexibility in the locomotion of prokaryotes, whose flagella are typically assumed to be rigid. Intriguingly, it shows how structural failure can be turned into biological function, a dramatic and elegant adaptation by the smallest organisms on the planet.

Associate Professor Roman Stocker
Coral Ecology and Disease: A Microscale Perspective
Tropical reef-building corals are complex biological systems comprised of a delicate balance of symbioses among the coral animal, intracellular dinoflagellates (zooxanthellae), bacteria, archaea, and viruses. We use microfluidic experiments and video microscopy to tease apart the chemical and physical interactions underpinning coral health and disease processes at the microscale. We study these processes both in the laboratory and in field settings, recently on Heron Island (Great Barrier Reef). We are currently focused on examining (i) pathogen behaviors and their response to host-derived chemical cues, and how this interaction is affected by increases in seawater temperature; and (ii) the complex ciliary flows that the coral animal creates along its surface and how it affects mass transport to and from the coral, in particular the export of oxygen from the zooxathellar photosynthesis.

Associate Professor Roman Stocker
Microscale Microbial Hotspots in the Ocean: Bacteria in the Phycosphere
Chemotaxis enables marine bacteria to utilize microscale nutrient patches and many marine bacteria are excellent at chemotaxis, markedly outperforming the classic chemotaxis model organism E. coli. In naturally occurring bacterial communities, we have observed the dramatic, fast formation of ephemeral accumulations of bacteria by chemotaxis into the ‘phycosphere’, the microscale region surrounding individual phytoplankton cells. Using high-resolution video microscopy and cell tracking, we have for the first time precisely dissected the spatio-temporal dynamics of this process. We are using this unique data set as input for a mathematical model that ‘scales up’ these microscale dynamics to yield predictions of the relative contribution of motile and non-motile bacteria to the utilization of nutrients from the phycosphere. By merging direct observations with ecological modeling, these results will help us understand resource competition among diverse bacterial communities and the roles of phytoplankton-bacteria interactions in biogeochemical cycling.

Associate Professor Roman Stocker
Fertilization in the Sea: Sperm Sensing and Biomechanics
Motility enables sperm cells (~50 microns long) to deliver their genetic cargo to egg cells for fertilization, a key step in the reproductive process for a host of organisms including mammals (especially humans) and external fertilizers (e.g. marine invertebrates). Similarly to many other motile single cells, sperm are guided by chemical gradients, but rather than seeking out nutrients, sperm are guided by egg-generated chemical signals. Complicating this process is the ubiquitous presence of fluid flow, be it from ocean turbulence for marine organisms or from ciliary-driven flows in the human reproductive tract. We are currently working to unravel the complex interactions between sperm and their physicochemical environment, specifically how sperm sense and respond to chemical gradients and how the flagellar biomechanics of sperm swimming are affected by external fluid flow. To accomplish this, we use a suite of novel microfluidic devices to control both chemical and hydrodynamic gradients and study the motility of sperm from a range of model systems including humans and various species of sea urchisn, through high-speed video microscopy and cell tracking.

Associate Professor Roman Stocker
Bacterial Turbulence: Collective Behavior at the Microscale
While bacteria often occur in dilute suspensions, in some cases these suspensions can be very dense. When this occurs, bacteria exhibit correlated dynamics on spatial scales much larger than an individual bacterium and generate flows faster than the individuals’ swimming speed. The resulting flows, visually similar to turbulence, can increase mixing and decrease viscosity. Using a new design of microfluidic devices, we study suspensions of Bacillus subtilis under carefully controlled oxygen gradients, to assess the interplay between the coherent large-scale motions of the suspension, oxygen transport, and the directional response of cells to oxygen gradients (aerotaxis).

Associate Professor Roman Stocker
Bacterial Competition in Turbulent Waters
In the ocean, some bacteria swim and some do not. Who wins and when? To find out, we developed a mathematical model of nutrient competition among bacteria in the ocean and implemented it within a Direct Numerical Simulation of turbulent flow, which takes into account the effect of turbulence on the transport and dispersion of nutrient patches and bacteria. We have found that (i) an optimal swimming speed guarantees the best advantage to swimmers and is broadly in agreement with observed swimming speeds, and (ii) an intermediate turbulence intensity optimally favors motility, because it creates chemical gradients and does not mix them away too rapidly. This approach is flexible, can include multiple other bacterial traits, and represents a promising new ecological framework to understand the evolution of different foraging strategies and the competition for nutrients among bacteria in the ocean.

Associate Professor Roman Stocker
Living at the Oil-water Interface: The Biophysics of Bacterial Oil Degradation
Approximately three million tons of crude oil find their way into the sea each year. In response to natural oil seeps occurring for millions of years, some marine microbes have evolved mechanisms to degrade oil, which they use as a carbon source for growth. Many species of oil-degrading bacteria are equipped with flagella that enable the cells to swim and actively pursue nutrient gradients in their local surroundings. We are interested in understanding and quantifying the link between motility at oil-water interfaces and how the encounter and attachment dynamics of microbes with oil influence oil degradation. We are characterizing the system at the microbe-oil droplet level using dedicated macro- and micro-fluidic devices and capturing the swimming behavior and attachment dynamics of individual bacteria near the interface with phase contrast and epifluorescent microscopy and image analysis. Quantifying the physical interaction of motile bacteria to liquid-liquid interfaces will promote a fundamental understanding of oil-microbe interactions in the ocean and potentially inform improved oil bioremediation strategies.

Associate Professor Roman Stocker
Bacterial Chemotaxis: Signal Integration and Adaptation
Chemotaxis, the ability of cells to detect and respond to a gradient in chemical concentration, plays a central role in microbial ecology. We develop new microfluidic approaches to create carefully controlled, spatial and temporal gradients of (single or multiple) chemical stimuli. We use these to study the motility and growth response of bacteria to transient stimuli, sensory adaptation, the integration of different signals, and the role of metabolism on chemotaxis (energytaxis).

Associate Professor Roman Stocker
Bacterial Biofilms: Surface Detachment and Quorum Sensing
Bacteria often adhere to surfaces, where they develop polymer-encased communities (biofilms) that display dramatic resistance to antibiotic treatment. The permanence of biofilms on surfaces thus poses serious risks of infection by and transmission of pathogens, so that a better understanding of bacterial detachment from surfaces may lead to novel strategies for biofilm disruption and removal. Using micro-contact printing, we can produce carefully controlled biofilms by creating hydrophobic patches on glass substrates, which strongly favor bacterial attachment and on which biofilms rapidly develop. These controlled patches then allow us to study a number of biofilm processes, including (i) the detachment of cells due to passage of air plugs and (ii) how cell-to-cell communication (quorum sensing) in biofilms depends on the size of the biofilm and the strength of the ambient flow.

Associate Professor Roman Stocker
Microfluidic Cell Sorting
For many applications, it is desirable to not only be able to visualize microbes and their interactions, but subsequently sort and sample them for further analysis. We are working on approaches to sort microbes in a number of settings, including (i) a microfluidic module for the sorting of phytoplankton cells to attach to FlowCytobot, an underwater flow cytometer developed at WHOI by Rob Olson and Heidi Sosik; and (ii) a microfluidic chemotaxis device that enables sorting of microbes according to their chemotactic abilities and preferences.

Associate Professor Roman Stocker
The Effect of Density Stratification on Marine Microbes and Particles
Peculiar fluid mechanics arise when the motion of a particle or the motility of a microbe are considered in the context of the density stratification that is widespread in the ocean, where it is caused by vertical temperature gradients (thermoclines) or salinity gradients (haloclines). Through numerical simulations and laboratory experiments, we have found that density stratification can considerably increase the drag on small settling particles, and in particular of porous particles such as marine snow, and it can alter the spatial signature and energy consumption of swimming microorganisms.

Assistant Professor Janelle Thompson
Experimental Microbial Ecology of Marine Anthozoa

Coral tissues harbor diverse communities of microbes, and increasing evidence suggests these communities provide beneficial functions-including nutrient cycling and pathogen protection. How these microbial communities are assembled and maintained remains a central question for understanding the role of microbes in health and disease. The starlet sea anemone Nematostella vectensis is emerging as a model for animal development and evolution because the phylum Cnidaria is one of the earliest branches on the animal tree of life. In addition, N. vectensis is closely related to corals and thus is a tractable laboratory model for probing the mechanisms of disease and disease resistance in this class of globally significant organisms (i.e. the Anthozoa). We have hypothesized that N. vectensis lives in association with a microbial community that supports host health. We are currently using a combination of isolation-based and cultivation-independent methods to explore the relationship between microbial community composition and the physiology of the N. vectensis host.

Assistant Professor Janelle Thompson
Ecology of Virulence

Reports of mass mortality in natural and cultivated marine populations are increasing worldwide, and many marine diseases have suspected microbial etiologies. We are currently using a combination of genetic tools to investigate the mechanisms by which Vibrios, closely related to V. harveyi and V. parahaemolyticus, cause disease and mortality in marine invertebrates. In addition, we are exploring the alternate roles of virulence mechanisms in environmental contexts outside of the animal host.

Assistant Professor Janelle Thompson
Microbiology of Carbon Sequestration

Carbon dioxide capture and storage (CCS) is currently being implemented as a strategy to mitigate atmospheric emissions of CO2 and help stabilize atmospheric greenhouse gas concentrations. In CCS, carbon dioxide is separated and captured from an industrial process stream before being compressed and injected deep underground into geological formations (e.g. hydrocarbon or saltwater-filled (saline) reservoirs) for storage on time scales of 1,000 years or more. Natural saline formations are biologically active environments that will be profoundly changed by the injection of CO2, potentially affecting both short-term injection operations and long-term storage of CO2. Little is known about how the subsurface microbial ecosystems will affect trapping mechanisms or the operational efficiency of CO2 injection into natural saline formations. We are investigating how geological carbon sequestration affects the subsurface microbiota and the biological processes that mediate potential biogeochemical transformations of subsurface carbon dioxide.

Geotechnical Engineering, Geomechanics and Geotechnology back to top back to top

Professor Herbert H. Einstein
Rock Fracture Characterization and Fracture Mechanics

Rock mass behavior, such as slope and tunnel stability and flow through rock is strongly affected by fractures (joints). Fractured rock flow and related mechanisms are particularly important in energy production, for example in “unconventionals” and engineered geothermal systems. This is a focal area for the MIT-CEE rock mechanics group. The major emphasis is to examine how fractures propagate and coalesce through lab experiments using high-speed observation, scanning electron microscope observations and nano-identations and acoustic emissions. The experimental information is then used to develop analytical models. Past research was sponsored by the National Science Foundation and the U.S. Department of Energy. Present research also involves experiments and modeling of hydraulic fracturing in the context of the Multiscale Shale Gas Collaborative sponsored by TOTAL-MITEI (see also research on shales, below).  For more information, visit the Video page for a short video showing some of this work. 

Professor Herbert H. Einstein
Tunnel and other Infrastructure Design and Construction

Tunneling is one of the most expensive and uncertain civil engineering endeavors. It is, therefore, essential to quantify and explicitly consider all factors that contribute to uncertainty in cost, time and resources. Several major computer-based tools (Decision Aids for Tunneling, Decision Aids for Tunnel Exploration) have already been developed and put to use to address uncertainty. Ongoing research extends this work to complex tunnel systems and other heavy infrastructures to develop a procedure that will make it possible to use experience gained from past projects, together with observations of a particular project, to update predictions about construction cost and time as the tunnel or other infrastructure is constructed.

Professor Herbert H. Einstein
Behavior of Shales

Shales, in the widest sense, are the most common near-surface rocks.  Within the last decade, they have become of great interest in conjunction with gas and oil extraction.  Shales are also of great interest in civil engineering because of their often problematic properties (low strength – high deformability – tendency to swell).  Professor Einstein’s research in this area has been going on for 40 years, first related to civil engineering problems and then resulted recently in models representing anisotropic behavior.  The present research is related to “tight shales” in conjunction with oil and gas extraction.  In the context of the project “Multiscale Shale Gas Collaborative”, sponsored by TOTAL-MITEI, propagation and coalescence of fractures in shales are being investigated.  This involves both experiments and modeling, which can be based on previous research with other types of rocks.  Very sophisticated testing procedures and advanced models are being developed and used.

Professor Herbert H. Einstein
Decision Analysis for EGS (Enhanced Geothermal Systems)

EGS rely on circulating water through rock fractures to extract heat and then through heat exchangers to eventually produce electricity in addition to directly useable heat. In this context, holes need to be drilled, artificial fractures created and the water circulation maintained through the lifetime of the system. Many uncertainties affect this system, and this research addresses the uncertainties related to the subsurface components.  Specifically, stochastic fracture pattern models and fracture flow models are combined to produce probabilistic flow models. In parallel, cost-time models for wells (drill holes) are developed. Finally, on the basis of the fracture flow and drill cost/time models, models will be created to predict the optimal location of the wells. The research is funded by the U.S. Department of Energy under the ARRA (American Recovery and Reinvestment Act) Program. 

Professor Herbert H. Einstein
Effect of Natural Hazards on Infrastructure Construction and Operation

Research on the physical aspects of landslides and associated hazard and risk analysis and decision making processes has been conducted for many years.  Recent extensions led to enhanced decision making procedures involving, for instance, Bayesian networks and including the effect of conducting exploration.  The present work is a project in which the effect of natural hazards on the transportation infrastructure construction and operation in Abu Dhabi is investigated.  The processes and tools developed in this context will be extended to other types of infrastructure and will form the basis for similar approaches in other locations.

Professor John R. Williams
Pore Scale Simulation For Enhanced Oil Recovery

In an oil reservoir, 20-40% of the oil can be recovered by primary development techniques. The rest remains trapped in the rock pores. Enhanced Oil Recovery (EOR) techniques, such as water flooding, gas injection, chemical injection and thermal stimulation, optimistically recover an additional 10-20% of the oil. This still leaves almost half of the oil trapped in the rock pores. The Department of Energy (DOE) has estimated that if “next generation” EOR is applied, the United States could generate an additional 240 billion barrels of recoverable oil resources - over 30 years supply at the present US consumption rate of 20 million barrels per day. For comparison, the Middle East holds an estimated 685 billion barrels that are recoverable and the tar sands of Alberta 300 billion recoverable barrels of “heavy” oil, with over a trillion barrels potentially recoverable using enhanced methods. We are researching new EOR technologies by providing understanding of the fundamental physical processes within a reservoir, particularly at the pore scale. We are developing the computational algorithms for pore scale simulation of oil reservoirs based on multi-scale, multi-physics models. The work leverages “particle” models based on a partition of unity class of techniques, including SPH and DEM.

Professor John R. Williams
Mutiscale, Multiphysics Simulation on Multicore Computers

A typical multiphysics simulation takes direct input from a microCT scan, at a resolution of some 8 billion voxels of data. Each grain of rock has a different shape and may be cemented to other grains. Furthermore, the surface properties of the grains influence the wetability of the rock/fluid system. The gas, water and oil in the pores, and the rock matrix are then subject to driving forces, mainly mechanical but also seismic, chemical and electrical. We have developed new algorithms to take advantage of shared memory multicore computers. The challenge is to be fast but also to be “thread safe”. We have shown that by tuning the task size to the hardware we can solve problems that were impossible even a few years ago.

Professor Andrew J. Whittle
Development of constitutive models for soils

  • Rate Effects in Clays
    Although there are many observations of rate dependent properties of clays in laboratory element tests there are no credible model formulations that consistently describe strain rate effects in shearing or creep and relaxation in compression. The current research aims to develop and validate an elastic-viscoplastic framework for clays that can extend prior elastoplastic models developed at MIT. The research makes extensive use of unique experimental data on rate dependent undrained shear behavior and effects of prior stress history. The goal is to develop a model that will resolve an enduring controversy (within the geotechnical community) regarding the coupling of consolidation and creep (secondary compression), and hence enable more reliable predictions of long-term ground movements for structures founded on soft clay.
  • Multiscale Modeling of Clays
    Recent advances in molecular modeling methods and nano-scale measurements of material properties offer a new paradigm for understanding the multi-scale behavior of complex natural materials such as clays. Recent studies at MIT have used molecular models to simulate the hydration of montmorillonite and to predict elastic properties at different hydration states. We have also used molecular models to investigate the interactions between clay platelets and hence, to develop the first meso-scale models of clay aggregates. Future research will extend these analyses to include distributions of particle sizes and different clay minerals. The long-term goal is to use the bottom-up approach to improve macroscopic models of clay behavior.
  • Thermo-Hydro-Mechanical Behavior of Clays
    The coupling of thermo-hydro-mechanical properties of clays is of great importance in problems relating to the containment of radioactive waste and ground source heat exchangers (shallow geothermal heating/cooling systems). Research on the latter was initiated through a three-way collaboration with colleagues at Tsinghua and Cambridge Universities. The MIT research aims to simulate ground response due to seasonal heating and cooling using the TTS model formulated by colleagues at Tsinghua University. The TTS model is based on a novel thermodynamic framework where coupling between thermal and mechanical properties is due to the exchange between bound and free water within the clay. There are only limited data available to evaluate the model and future research will need to conduct more extensive validation.
  • Ground Movements for Expansive Soil Subgrades
    Many parts of the continental US are underlain by expansive clays that undergo significant changes in volume (swelling or shrinkage) due to seasonal changes in moisture content. Existing methods for estimating these effects are based on simplified empirical procedures that are grossly overconservative. A new research project aims to develop more reliable methods of analysis by simulating strains of partially saturated clay due to seasonal changes in matric suction. The research will calibrate properties for a complex elastoplastic model (BExM developed at UPC, Barcelona) based on a program of laboratory tests on an expansive clay and to install a field station to monitor pore pressures and ground deformations at a test site in Texas.

Professor Andrew J. Whittle
Analyses of Soil-Structure Interactions

  • Seismic Retrofit of Pile-Deck Wharf Structures
    Many port facilities in the North America are vulnerable to severe damage in major seismic events. The most critical structures are pile-supported wharf decks that are often founded within loose/uncompacted fills. Lateral spreading (and potential liquefaction) of the fill slopes during an earthquake can cause bending failure of the piles and collapse of the wharf. The main goal of this research is to investigate the effectiveness of retrofit methods for improving seismic performance while causing minimal disruption of port operations. Research on this topic was originally supported by NSF through a NEESR-Grand Challenge project (led by colleagues at Georgia Tech.). The MIT research used the framework of OpenSees to simulate the underlying (free-field) ground response that is then coupled to the structure through macro-element representations of pile-soil interactions. Studies to date have shown the effectiveness of PV drains as a method of mitigating structural damage for a broad suite of ground motions. On-going studies aim to improve the modeling of cyclic response of the soils to enable more realistic predictions of seismically induced slope failures.
  • Conductor-Soil Interaction
    The oil spill resulting from the blowout of the Macondo Well and sinking of the Deepwater Horizon drilling ship has raised many critical questions regarding the safety of offshore drilling operations. A multi-disciplinary research team at MIT is currently investigating possible failure mechanisms associated with drilling rig drift-off or drive-off. These processes generate large loads and potential failure of the conductor below the blowout preventer. Geotechnical research is focused on realistic analyses of the conductor-soil interactions to simulate the large lateral deformations of the embedded conductor within the soft marine clay sediments and subsequent dynamic response for riser separation. The analyses use constitutive models developed previously at MIT and are to be validated through comparisons with results of physical model tests (carried out in a large geotechnical centrifuge facility at C-Core in St Johns) for conditions typically found at deepwater sites in the Gulf of Mexico. The ultimate goal is to develop simplified methods for representing conductor-soil interactions in simulations of the entire conductor-riser system.
  • Ground Movements due to Soft Ground Tunneling
    The prediction and mitigation of damage caused by construction-induced ground movements represents a major factor in the design of tunnels. This is especially important for shallow tunnels in congested urban environments, where expensive remedial measures such as compensation grouting or structural underpinning must be considered prior to construction. The goal of this research is to develop and evaluate new methods for predicting ground response due to tunneling. Research supported by Ferrovial-Agroman simulates Earth Pressure Balance (EBP) tunnel boring machines in clay. The analyses consider the role of face pressure, grouting around the precast lining rings and complex (non-linear and inelastic) properties of the surrounding soil. Site-specific predictions have been compared with recent field measurements during construction of Crossrail tunnels in London and with results of simplified analytical models. Research is now focused on interactions of the tunnels with overlying buildings.

Professor Andrew J. Whittle
Monitoring & Control of Underground Infrastructure

  • Real Time Measurement and Modeling of Excavation Support Systems
    The designs of Temporary Earth Retaining Systems (TERS) for deep excavations are heavily regulated to minimize risks during construction. The construction is then closely monitored to ensure conformance with expected behavior and the performance is deemed acceptable while measurements remain below pre-set trigger levels. While this paradigm ensures that TERS are safe and cause minimal damage, there is little motivation to reduce the spiraling costs associated with overly conservative designs. This research aims to integrate recent advances in computational analyses (massive 3D FE models) and in the design of low cost wireless sensors, in order to develop a capability for ‘real-time’ data interpretation and prediction. This methodology will use the field monitoring data to update and re-evaluate model predictions during construction and hence, offer a real-time observational framework that can reduce risk while enabling more creative and cost effective designs of TERS. The current research is funded through the Center for Environmental Sensing and Modeling and is being conducted in collaboration with the Land Transport Authority in Singapore. The current involves applications for a series of subway station projects under construction for the new Thomson Line. Next generation wireless strain gauges are being designed and tested in collaboration with colleagues at Coventry University.
  • Monitoring and Control in Water Distribution Networks
    Many cities worldwide must deal with the maintenance of aging infrastructures such as water distribution systems where there are significant losses due to leakage, increasingly frequent failures due to pipe bursts and growing concerns regarding water quality in the pipe network. Prior research (WaterWiSe@sg) funded through the Center for Environmental Sensing and Modeling, and carried out in collaboration with the Singapore Public Utilities Board (PUB) has led to a proof-of-concept, end-to-end system for continuous remote monitoring of the water distribution system in downtown Singapore (FCPH zone), including a generic wireless sensing platform capable of measuring hydraulic (pressure and flow), acoustic (hydrophone) and water quality parameters (pH, ORP, conductivity, turbidity), a data collection and visualization infrastructure, and a set of modeling and analysis tools. The testbed provides a unique opportunity for advancing research capabilities. Current research includes the development of analytical tools to 1) optimize the placement of sensors within the complex network, 2) improve the detection and localization of hydraulic and water quality anomalies; and 3) automate tools that can enable sub-zones of the system to be isolated (to reduce public health risks). Further studies aim to measure and characterize the development of biofilms within the water pipes.

Hydrology and Hydroclimatology back to top back to top

Professor Elfatih Eltahir
Research in the Eltahir group is recognized for defining the role of land surface hydrology in shaping the climate system at regional scales. We seek to improve understanding of natural hydrologic phenomena, motivated by several environmental problems related to the impacts of deforestation, desertification and climate change. We develop state-of-the-art numerical models that are suited for simulation of climate processes at the regional scale. We test these models against satellite observations and archived data sets of hydrologic and atmospheric variables, as well as data collected in our own field campaigns. For more information and to see ongoing research projects, please visit the Eltahir website: http://eltahir.mit.edu

Professor Dara Entekhabi
Earth System Monitoring Through Space- and Air-borne Remote Sensing

The objective of this project is to develop satellite multi-pass estimation and retrieval models for surface soil moisture to support the forthcoming Soil Moisture Active Passive (SMAP) satellite mission. The goal of the mission is to make global soil moisture and freeze/thaw measurements, data essential to the accuracy of weather forecasts and predictions of global carbon cycle and climate. SMAP will use low-frequency microwave sensors to map global fields of high-resolution radar backscatter and coarse-resolution but highly accurate radiobrightness simultaneously. The anticipated performance of the algorithm will be tested using a numerical algorithm test-bed. The multi-pass estimation and retrieval is anticipated to reduce the dependence of algorithms on auxiliary information on vegetation characteristics and other parameters. We propose to develop a combined estimation-retrieval algorithm that separates the time-scales of the various contributions to the signal and to the error. The new algorithm will use the separation of time scales together with multi-pass measurements in order to estimate values for the parameters and for the errors.
For more information: http://smap.jpl.nasa.gov/
or http://cee.mit.edu/node/1088

Professor Dara Entekhabi
Smart Sensing for Ground-Truth Tests of Remote Sensing Retrievals

The proposed project addresses the topic of "smart sensing." It is motivated by a sensor-web measurement scenario including spaceborne and in-situ assets. The objective of the technology proposed is to enable a guided/adaptive sampling strategy for the in-situ sensor network to meet the measurement validation objectives of the spaceborne sensors with respect to resolution and accuracy. The sensor nodes are guided to perform as macro-instrument measuring processes at the scale of the satellite footprint, hence meeting the requirements for the difficult problem of validation of satellite measurements. The science measurement considered is the surface-to-depth profiles of soil moisture estimated from satellite radars and radiometers, with calibration/validation using in-situ sensors.

Professor Dara Entekhabi
Global Ecology From Space

The objective of this project is to design and implement a new “virtual” science mission based essentially on the opportunistic measurements from SMAP and OCO-2. This new science mission is not related to either of the two mission science requirements but it is enabled by their instrument capabilities. The science question driving the proposed project is: What are the carbon allocation strategies for terrestrial ecosystems under water- and under light-limitation?  Photosynthesis is a carbon source for plants but how they allocate this resource among plant components depends on available water and light, nutrient limitations and controls the residence time of this fixed carbon. With the high-resolution and direct observations of plant structure and function enabled by SMAP and OCO-2 instrument data, an unprecedented perspective on the science question is enabled.  Neither SMAP nor OCO-2 project include this use of their instrument data for a new application. Initially, the seasonal cycle will be used as an analogue of water and light limitation.  

Professor Dara Entekhabi
Drought Monitoring and Forecasting From Space

The objective of this project is the development of a robust drought forecasting system.  The new systems is built on the foundations of a better understanding of the ‘drought anatomy’ as well as an ability to monitor drought across large domains. The following stages define the research on this topic:  (1) Produce a regional typology of drought evolutions in order to improve forecast development. This objective will identify and evaluate distinct droughts of each (Meteorological, Agricultural, and Hydrological) type and how they evolve across spatio-temporal scales using NASA’s multi-mission satellite data (e.g., GPCP, AMSRE, SMOS and SMAP), derived products and ground based observations (e.g., USGS stream gauge/water level anomalies and USDA SCAN). This will also help us in mapping the basin-average drought cascades over the multi-decadal record. (2) Improve the drought monitoring capabilities of NIDIS/NDMC. We propose to incorporate NASA’s multi-mission satellite products including recent SMAP data to the NIDIS’s existing suite of drought monitoring tools. Currently, the incorporation and use of remotely sensed soil moisture of current conditions for drought monitoring and early warning has been very limited to almost nonexistent.      

Professor Charles Harvey
Carbon Fluxes in Peat-land Rain Forests

Peat-land rain forests in Malaysia and Indonesia store tremendous amounts of carbon in their soils. These forests are now being cut and replaced by palm-oil plantations to provide biofuel. In this project, we will quantify the rates of carbon dioxide and methane uptake and release from these tropical soils under natural conditions, and after the destruction of the forest. We will develop and deploy sensors in the soils to measure the characteristics that control carbon transformations (such as moisture content), and on towers above the forest to measure carbon exchanges with the atmosphere. We will then develop predictive models of the relevant biogeochemical processes so that these models can be employed to reduce carbon release.

Associate Professor Ruben Juanes
Phase-field Modeling of Multiphase Flow

The displacement of one fluid by another in a porous medium can give rise to a rich variety of hydrodynamic instabilities. Beyond their scientific value as fascinating models of pattern formation, unstable porous-media flows are essential to understanding many natural and man-made processes, including water infiltration in soil, enhanced oil recovery from hydrocarbon reservoirs, and CO2 sequestration in deep saline aquifers. The inability of traditional continuum equations to reproduce the formation of the complex patterns observed in experiments highlights the need for new theoretical approaches. Our research group has developed a new paradigm for modeling multiphase flow at the continuum scale—phase-field modeling—which recognizes explicitly that fluid-fluid displacements are out of thermodynamic equilibrium. (Read more)

Associate Professor Ruben Juanes
Geological CO2 Sequestration

In carbon dioxide capture and storage (CCS), CO2 is captured from the flue gas of power plants and then injected underground into geologic reservoirs like deep saline aquifers for long-term storage. While CCS may be critical for the continued used of fossil fuels in a carbon-constrained world, its deployment has been hindered by uncertainty in geologic storage capacities and sustainable injection rates. Our work has addressed this critical question (how much can be injected?) by developing storage capacity estimates that, unlike previous estimates, are based on the fluid mechanics of CO2 injection, migration, and trapping. (Read more)

Associate Professor Ruben Juanes
Gas Migration in Unconsolidated Sediments

Methane is a potent greenhouse gas, but its effects on Earth’s climate remain poorly constrained, in part due to uncertainties in global methane fluxes to the atmosphere. An important source of atmospheric methane is the methane generated in organic‐rich sediments underlying surface water bodies, including lakes, wetlands, and the ocean. The fraction of the methane that reaches the atmosphere depends critically on the mode and spatiotemporal characteristics of free‐gas venting from the underlying sediments, which in turn is controlled by the interplay between gas migration and sediment mechanics. Our research group has developed grain-scale computational model and carefully-controlled laboratory experiments to investigate the coupling between multiphase fluid flow and sediment mechanics. (Read more)

Associate Professor Ruben Juanes
Mixing in Porous Media

The rate at which fluids mix in a porous medium controls the rate at which reactions occur, or the rate at which the physicochemical properties of the mixture (such as fluid density and viscosity) vary. Determining and possibly enhancing mixing is critical in both microfluidic devices and in geologic processes like improved oil recovery by miscible flooding or CO2 sequestration. (Read more)

Associate Professor Ruben Juanes
Flow Through Fractured Media

Flow through fractures is essential in the risk assessment of nuclear waste disposal, oil and gas production from fractured carbonates, and leakage risk in geological CO2 storage. It is well known that flow through fractures leads to anomalous transport, that is, to spreading and mixing behavior that deviates from classical diffusion. Our goal is to find an effective (stochastic) macroscopic description of transport through fracture networks, first for simple lattice models, and then for geologically realistic fracture networks. New quantitative understanding of flow and transport through fractured media could prove instrumental in model inversion and risk assessment. (Read more)

Associate Professor Ruben Juanes
Coupled Flow and Geomechanics

Coupled flow and geomechanics has emerged as one of the critical research areas in reservoir science and engineering. While the recognition that flow and deformation are strongly-coupled processes is not new, current tools are insufficient to adequately forecast reservoir deformation in response to oil and gas production, especially in stress-sensitive or faulted reservoirs. We have developed efficient algorithms for sequential coupling flow and deformation, and implemented them in a unique modeling tool for the simulation of coupled flow and geomechanics in fractured and faulted reservoirs. (Read more)

Associate Professor Ruben Juanes
Dynamic Processes on Complex Networks

The study of dynamic processes that take place in complex networks has emerged as one the most exciting areas of research in a wide variety of scientific fields, from statistical physics and systems biology to human mobility and the social sciences. We study transport and epidemic spreading in human mobility networks. We are particularly interested in behavioral feedbacks, where individuals dynamically change their strategies, therefore shaping the network efficiency and robustness. (Read more)

Professor Dennis McLaughlin
Data Assimilation for Chaotic Systems

In this project, we will consider methods for combining model predictions and measurements for chaotic systems such as the atmosphere and ocean. Chaotic systems are characterized by rapid growth of small changes in system variables. This makes the system's behavior difficult to predict unless the diverging variables are frequently updated with measurements. The procedures used to perform measurement updates for environmental applications are generally based on linear assumptions that are not compatible with the nonlinear dynamics of chaotic systems. This project examines some new estimation methods that may be able to provide better characterization and forecasting capabilities for chaotic environmental systems.

Professor Dennis McLaughlin
Real-Time Control for Petroleum Applications

This project considers the problem of designing control strategies for increasing oil and gas recovery in petroleum reservoirs. The reservoir control problem is complicated by the large uncertainty in subsurface geological properties that control the flow of water, oil and gas in the subsurface. This project will focus on the development of robust control strategies that recognize the role of geological uncertainty and explicitly consider connections between control decisions and property estimation.

Professor Dennis McLaughlin
Implications of Climate Change for Food Production in China

China currently depends almost entirely on domestically grown food. This project uses an integrated agricultural-hydrologic model to examine the connections between natural resources (land and water) and food production in China. Previous work has quantified these connections for present climate conditions. The new project will examine the implications of climate change, including both long-term regional trends and inter-annual variability in precipitation and temperature. This project has significant public policy implications but is primarily focused on better understanding relevant hydrologic factors.
For more information:
http://web.mit.edu/newsoffice/2005/china.html

Professor Dennis McLaughlin
Feature-Based Data Assimilation for Environmental Systems

Many environmental systems are characterized by distinctive spatial features such as rainstorms, ocean currents, algae blooms, wildfires and chemical plumes, among others. Traditional data assimilation methods are not always able to preserve the structure of these features when they combine model forecasts with measurements. One way to address this problem is to reformulate the data assimilation process to more explicitly recognize the role of spatial structure. The resulting feature-based approach works with geometrical objects of uncertain size and shape. Many of the methods required to estimate these shapes from data rely on image-processing methods. However, it is also important to include physical constraints not always considered in image processing applications. This project will focus on developing new feature-based data assimilation methods that are applicable to a range of applications.

Professor Daniele Veneziano
Fractal Methods in Hydrology

Virtually all areas of hydrology have been deeply influenced by the concepts of fractality and scale invariance. The roots of scale invariance in hydrology can be traced to the early work of Robert E. Horton, R. L. Shreve and J. T. Hack on the topology and metric properties of river networks and of Henry Hurst on river flow. These early developments uncovered symmetries and laws that only later were recognized as manifestations of scale invariance. Lucien Le Cam, who in the early 1960s pioneered the use of multiscale pulse models of rainfall, provided renewed impetus to scale-based models. Fractal approaches in hydrology have become more rigorous and widespread since Benoit Mandelbrot systematized fractal geometry and discovered multifractal measures. Professor Veneziano and collaborators have a longstanding interest in the area of scale-invariant methods, including the construction of scale-invariant processes, their properties and the inference of scale invariance from data. They have applied these methods to several areas of hydrology, including rainfall extremes, fluvial erosion topography and flow through random porous media.

 

Infrastructure Systems back to top

 Assistant Professor Saurabh Amin
Robust Infrastructure Diagnostics and Control
Networked control systems (NCS) can be viewed as a set of networked agents consisting of sensors, actuators, computational units, and communication devices. NCS are increasingly deployed to facilitate real-time monitoring and control of large-scale critical infrastructures. We are specifically interested in NCS for energy, transportation, and water distribution infrastructures. Our goal is to develop (i) model-based tools for incident detection and fault/attack diagnosis; (ii) network control algorithms for closed-loop stability and robustness; (iii) adaptive mechanisms for NCS reconfiguration in the presence of extreme disturbances. We believe that these control specific detection and response mechanisms will increase the infrastructures’ survivability, and reduce risks of cascading failures.  

Assistant Professor Saurabh Amin
Incentive Mechanisms for Network Security and Reliability
Our goal is to study the incentives for reliability and security of networked infrastructure systems. These systems are predominantly managed by profit-driven, private entities. The presence incomplete and asymmetric information results in a gap between the individually and socially optimal incentives. We use game theoretic models to characterize the optimal incentives for both individual and social settings. This provides new tools to evaluate the mechanisms aimed at improving network reliability and security. Of particular interest are mechanisms for (i) congestion management (and demand shaping) in smart infrastructures, and (ii) reduction of interdependent network risks.

Assistant Professor Saurabh Amin
Testbed for Networked Control Systems
We are developing a testbed to study the effect of correlated hardware malfunctions and software flaws on the survivability of networked control systems. The testbed capabilities will include: (i) reconfigurable and computationally efficient implementations of diagnostic tools and control methods; (ii) emulations and simulations of control system components; and (iii) experiments for humans and hardware in the loop. We will use a multi-scale approach to integrate strategic decision making with operational execution of robust control strategies. This flexible and powerful cyber-physical experimental facility will be made available to the larger research community.  

Professor Cynthia Barnhart*  
Optimization-Based Data Mining

The goal of this project is to develop new optimization-based methods of data mining that can be applied to a wide range of problems of interest to us and to society. To evaluate our new techniques, we will apply them to optimizing drug combinations in the treatment of cancer. Our objective is to build models that utilize all available information related to all types of cancer, since many drugs are commonly used against multiple cancers. We intend to identify drug combinations that seem very promising and propose new clinical trials to test their effectiveness. In addition, we aspire to build a system that takes information about existing clinical trials and, together with historical information, decides adaptively how to combine trials, stop them early and start new ones. Early action is particularly important, as cancer patients do not have the luxury of time. Other potential application areas for this work include sensor management; intelligence, surveillance, and reconnaissance/strike operations; logistics; and traffic management.
*With Professor Dimitris Bertsimas of the MIT Sloan School of Management

Assistant Professor  Marta González 
Dynamics of Land Use in Urban Spaces

The proliferation of mobile computing devices, principally cellular phones, have become an invaluable tool, helping us understand how cities function as a complex system so that we can we can increase the effectiveness and efficiency of urban planning and design. Behaviors can be decomposed into just a few fundamental patterns that can then be used to differentiate between groups of individuals or types of spaces. The properties of these patterns have been explored, laying the groundwork to discover how people move across space and interact with each other. We propose to expand upon previous work in two important ways: scaling methods from the college campus to entire cities, and exploring not just how far people are traveling, but how they are using these locations dynamically in time. To do this, we will leverage data generated from millions of mobile phone users in a major metropolitan area as they access location-based services on their phones. A phone’s ability to accurately locate itself to WiFi access points within 25m allows us to measure dynamic population density for roughly every intersection of a city at every hour of the day. Additionally, we will compare the results with survey data using data mining techniques, which have not been applied in this context before. Since the survey collected over the metropolitan area is conducted by the metropolitan planning organization for the regional transportation planning purposes, it is a representative sample of the total population of the region, these data will be used to sample and compare the land use and trips captured from the mobile phone. Impact: This is a significant improvement over the static and often outdated classifications dictated by traditional zoning and urban planning regulations. Moreover, a deeper understanding of population flow is critical to planning police service, or public health attempts to better prepare a city to resist disease outbreaks.

Assistant Professor  Marta González 
Analytical Model and Measurements of Aggregated Mobility Networks

The origin-destination matrix (OD), is a network of aggregated trips that allows one to test some ideas about the structure of human movement, there are many factors that control it — land use, location of industries and residential areas, accessibility, etc. — and it seems difficult to provide a general and simple enough model. Most of the studies are descriptive or empirical, i.e. they either present case studies or use regression analysis to quantify the influence on mobility characteristics of factors like neighborhood density, distance from the city center, measures of land use mix, street connectivity and socioeconomic factors. Fewer studies are theoretical, deriving mobility descriptors from assumed spatial distributions of trip origins and potential destinations and models for trip initiation and the choice of destination and transportation mode. Impact: We will validate and calibrate multiplicative models by analyzing the spatial distribution of population (a surrogate for demand) inside metropolitan areas in different countries. We plan to make extensive analyses of population and supply data to support the models of supply and demand and its effect in trips. Using mobile phones we will compare trip length distributions and construct mobility networks and try to provide a unified framework to test OD models.

Professor Richard de Neufville
Development of Flexibility in Design

This research focuses on developing flexibility in design, which frequently adds about 25 percent to the expected value of projects compared to traditional designs optimized around specific forecasts and requirements. Our team works on a broad range of applications: transportation and the development of infrastructure; real estate and building design; the design of oil platforms in the traditional civil engineering context; plus work with the mining industry, health care, defense systems, sustainable energy and other fields. Student researchers should combine excellent engineering skills with an interest in economics and project valuation. Practical industrial experience and the ability to write well are a plus. Students interested in this work are encouraged to visit Professor de Neufville's website and read some of his papers at http://ardent.mit.edu/real_options/Common_course_materials/papers.html or his book Flexibility in Engineering Design (MIT Press, 2011) prior to contacting him at for more information at ardent@mit.edu

Professor Richard de Neufville
Airport Systems Planning and Design

This long-term effort investigates issues in the systems design of both individual airports and multi-airport systems. Please consult the recent textbook we wrote on the subject: Airport Systems Planning, Design, and Management 2nd edition (McGraw-Hill, 2013). My particular concern is with the configuration and design of the airport "ground side", that is the airport passenger buildings, airport access, and the competition between regional airports. See papers at http://ardent.mit.edu/airports/de_Neufville_airport_papers.html. Contact at ardent@mit.edu.

Senior Lecturer Peter Shanahan
Non-point-Source Studies for in Singapore Catchments
This project seeks to understand the sources of human fecal contamination and other pollutants to Singapore’s reservoirs, to identify appropriate environmental tracers for such contamination, to understand the association between land use and contamination sources, and to evaluate best management practices for control of non-point-source pollution in Singapore.  

Professor Joseph Sussman
Cities as Complex Systems

Much has been written over the years about how cities develop. This research considers cities as complex systems, with characteristics of other complex systems-such as nonlinearity, uncertainty, emergent properties, adaptation, counterintuitive and policy-resistant behaviors, difference between short- and long-term effects, effects at a distance (geographically), high sensitivity to initial conditions and so forth. In this project we endeavor to better understand the behavior of urban areas and to develop strategies for improving city "performance."

Professor John R. Williams
Green Computing – Optimization of Data Centers Across the Globe

Data centers around the globe contain terabytes of data necessary for large enterprises to function efficiently. The data resides in both Enterprise Resource Planning (ERP) systems and Product Lifecycle Management (PLM) systems. The conflicting goal is to have data available locally (in the nearest data center) while at the same time making sure this data is the most up-to-date available. We are building a simulator to test out the feasibility of reducing the number of data centers a company needs by locating synchronization information at a single data center. The simulator is based on MIT technology developed for simulating supply chains with billions of events occurring every day.

Professor John R. Williams
Smart Grid - Next Generation Utility Systems

Reducing the demand side of our energy needs can be achieved by reducing and optimizing our use of energy in transportation and in the heating and cooling of buildings. The US Green Building Coalition estimates that US buildings account for 39 percent of all energy use, and 38% of all CO2 emissions. Transportation consumes 29% of all energy.  This project targets some of the key implementation challenges of the smart grid: The Smart grid will consist of the electricity distribution network including the supplier and consumers and of a parallel monitor and control network (Grid Control Network). The Grid Control Network will be an IP based network. There will be other players in the eco systems building the Grid Control Network and connecting it to the electricity grid. This work focuses on building applications for increasing energy efficiency and peak shaving and on securing the Grid Control Network.  MIT and SAP are collaborating to build a real time meter data unification system capable of handling ten million customers.

Mechanics of Materials and Structures back to top back to top

Professor Markus J. Buehler
Materials Science of Amyloid Protein Nanomaterials

As part of a larger effort to explain the structural hierarchy and strength of high-performance biological materials, this project will investigate the mechanical properties of individual proteins and protein materials at the nanoscale. The focus will be the assembly, deformation and fracture properties of beta-sheet protein structures found in amyloid fibrils (highly ordered beta-sheet based fibril structures found in tissue) and silk nanocrystals using molecular dynamics simulations. Beta-sheet structures are abundant in many strong materials such as spider silk and muscle tissue, and are linked to diseases such as Alzheimer's and Parkinson's. Common to these materials is their ability to self-assemble into highly ordered, robust and sturdy fibrillar protein deposits. This project will investigate the mechanical behavior of the fibril and crystal forming structures using molecular dynamics simulations to explain how the specific structural and chemical properties of simple protein building blocks lead to such material growth phenomena. The insight gained from this study could be beneficial for developing new biomimetic nano-structured materials and novel noninvasive drug delivery systems.

Professor Markus J. Buehler
Mechanics of Chemically Complex, Hierarchical Nanostructured Protein-Based Materials Under Extreme Conditions

Evolution in nature has yielded a vast array of biological materials that are involved in critical life functions. Bone, providing structure to our body, or spider silk, used for prey procurement, are examples of fascinating materials that have incredible elasticity and strength. To date, scientists have been unable to create a number of these materials with similar properties, primarily due to the lack of understanding of how particular arrangements of atoms and molecules give rise to their unique material properties. This project will use large-scale atomistic modeling to elucidate how building blocks at the nanoscale define material properties at the macroscale. Combining knowledge from nanotechnology and biological sciences will enable the development of new materials, designed with molecular precision, that can help us understand, and perhaps cure, diseases that currently ail humanity.

Professor Markus J. Buehler
Protein-Inspiried Hierarchical Biomimetic Materials

Hierarchical biological protein materials are intriguing examples of multifunctional materials that combine disparate properties such as robustness, high strength, high elasticity, controllability and the ability to self-assemble and self-heal. In this project, fundamental concepts will be investigated via the analysis of two classes of protein materials: the beta-sheet rich spider silk and amyloid protein structure, and the alpha-helical intermediate filament motif found in the cell's cytoskeleton, also forming the basis of wool and hair. While the spider silk motif leads to highly elastic, strong fibrils, the intermediate filament protein represents a multifunctional self-organizing protein network. We will employ an innovative approach that combines theoretical analyses based on continuum-statistical theories with large-scale atomistic-based multi-scale simulation implemented on massively parallelized supercomputers. Our goal is to develop an atomistically informed, hierarchical continuum theory of protein materials that combines structural mechanics, statistical mechanics and chemistry, providing quantitative predictions of the elastic and strength properties of protein materials throughout a vast range of time scales.

Professor Oral Buyukozturk
Moisture-Affected Debonding in FRP-Retrofitted Concrete Systems-An Interface Fracture Approach

Fiber reinforced polymer (FRP) retrofit systems for concrete structures have been widely used in the past 10 years, and their short-term debonding behavior has been studied extensively. Nevertheless, the long-term performance and durability of these systems remain largely uncertain. In this project, comprehensive experimental and analytical investigations of debonding in FRP-bonded concrete systems are performed under long-term environmental exposure to develop mechanics-based predictive failure models and related design tools for these systems. Our experimental approach involves an investigation of debonding under moisture ingress, moisture reversal and cyclic moisture conditioning using the concept of fracture mechanics. Synergistic analysis and correlation studies are conducted to incorporate this quantification method and experimental data into the design of retrofitted concrete structures strengthened with FRP to prevent premature failure due to long-term environmental exposure.

Professor Oral Buyukozturk
Atomistic Simulation of Interface Fracture in Bilayer Material Systems

Structural innovations often use multilayer material systems consisting of substrates and interfaces. Interface performance and related failures in such layered systems can play a critical role in overall safety-especially when initial defects are present at the interfaces or in the substrates. Fracture of the substrate materials or interfaces under various mechanical and environmental effects essentially involves atomistic deformation and breaking of chemical bonds between molecules. Molecular dynamics (MD) simulation allows researchers and engineers to study the fracture process in multilayered material systems at the microscopic level. The objective of this research is to use MD simulation to understand interface fracture behavior in bilayer material systems (i.e. crack initiation and propagation direction) and the effects of material and interface properties. Motivated by the safety assessment of complex structural systems involving layers of different polymeric and concrete material properties, this study is conducted in collaboration with Assistant Professor Markus J. Buehler of the Laboratory of Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering.

Professor Oral Buyukozturk
Material Property Characterization of Concrete/Epoxy System

Understanding the durability of concrete/epoxy interfaces is becoming essential as the use of these systems in applications such as fiber reinforced polymer (FRP) strengthening and retrofitting of concrete structures is becoming increasingly popular. Prior research in this area has indicated that moisture-affected debonding in an FRP-bonded concrete system is a complex phenomenon that may often involve a distinctive dry-to-wet debonding mode shift from material decohesion (concrete delamination) to interface separation (concrete/epoxy interface) in which the concrete/epoxy interface becomes the critical region of failure. Such premature failures may occur regardless of the durability of individual constituent materials. Thus, the durability of FRP-bonded concrete is governed by the microstructure of the concrete/epoxy interface as affected by moisture ingress. In this project, fracture toughness of concrete/epoxy interfaces as affected by combinations of various degrees of moisture ingress and temperature levels is quantified. For this purpose, sandwich beam specimens containing concrete/epoxy interfaces are tested and analyzed using the concepts of fracture mechanics.

Professor Oral Buyukozturk
Development of the Concept of Defect Criticality

Extensive research has been conducted on the behavior of reinforced concrete columns with perfectly bonded fiber reinforced polymer (FRP), but little attention has been paid to the effect of possible initial defects on the structural performance of FRP-confined (or wrapped) concrete columns. This project explores the effect of defect size on the integrity of FRP-confined concrete, which governs the strength and deformability of the structural element. The effect of initial defects on FRP-retrofitted concrete columns appears more complicated than that on FRP-retrofitted concrete beams. In the FRP-retrofitted concrete beam, propagation of a crack from an initial defect (pre-crack) at the interface may start as a local failure and be followed by a rapid global failure. In a FRP-confined concrete column, the propagation of the initial defect may not lead to global failure. In general, such a phenomenon alters the confining pressure provided by the FRP, leading to stress redistribution and weakening of the structure. Deformation behavior and final failure may greatly depend on defect criticality. The objective of this research is to develop an in-depth mechanistic understanding of initial defect-induced fracture-through proper quantification-and to establish a link between local fracture and global failure in FRP-confined concrete. This work will inform future design guideline development and life-cycle predictive capability.

Professor Franz-Josef Ulm
Atomistic Simulation of Nanocomposites

Atomistic simulation of nanocomposites can provide deep insight into the smallest building block of materials. The aim of our research is to examine material behavior systematically, at the nano level, and correlate properties to higher scales. We focus on calcium silicate hydrate (C-S-H), a hydrated nanocomposite known to be the structure of cement paste materials. The molecular dynamics method and ab initio calculations are used to simulate and predict the mechanical properties of C-S-H.

Professor Franz-Josef Ulm
Microporomechanical Modeling of Shale-the GeoGenome Approach

Shales are made of highly compacted clay particles of sub-micrometer size, nanometric porosity and different mineral compositions. Understanding the mechanical properties of shale is key to success in many fields of petroleum engineering and geophysics, ranging from seismic exploration to well drilling and production. Adequate knowledge of shale poromechanics is also important for the development of sustainable nuclear waste storage solutions. The challenge lies in how to translate the highly heterogenous nature of shale into new predictive models of its mechanical properties. In this project, the micromechanical modeling of shale is framed within the GeoGenomeTM approach, which is: break down materials to a scale where the mechanical behavior is governed by invariant properties, then upscale this behavior to the macroscale. Using this approach, we have been able to identify the building blocks that delineate the nanoscale behavior of the load-bearing clay phase in shale materials. The microporomechanics model is being validated at multiple-length scales using novel experimental results from nanoindentation, as well as data from conventional macroscopic techniques for elasticity and strength assessments.

Professor Daniele Veneziano
Variability of Bulk Moduli and Toughness of Heterogeneous Materials

There is currently much interest in understanding the effect of heterogeneities on the bulk properties of natural materials and exploiting such effects to design new materials with superior characteristics. Random variations are present in many natural and man-made materials such as bone, concrete and fiber-reinforced composites and can be synthesized with modern additive manufacturing techniques such as 3D printing. We are working on the problem of analytically predicting the variability of the bulk mechanical properties (stiffness, strength, fracture toughness…) induced by the heterogeneities for broad classes of randomly heterogeneous materials. The results are needed to address safety and durability problems and ultimately design for target performance levels.

Transportation Systems back to top back to top

Professor Cynthia Barnhart*
The National Air Transportation System as a Reconfigurable Engineered System

The smooth and reliable functioning of the National Air Transportation System (NATS) is vital to the nation's economy. NATS generates about $150 billion in revenue and transports more than 700 million people annually. Yet, disturbance-induced delays-typically problems caused by weather-cost the industry and consumers more than $10 billion each year. The goal of this research is to work toward the autonomous reconfigurability of NATS, so that the system can respond to any disturbance. Researchers will model NATS as a distributed multiagent control problem, and consider the autonomous reconfigurability of NATS through the development of theory and algorithms for dynamic and distributed robust optimization models on multiple scales and granularities. Our goal is to investigate, (1) how local interventions can be made to work autonomously, robustly and synergistically; (2) what operating environments, pricing and other incentives might bring about such a paradigm shift in NATS; and (3) what the potential national benefits from such an integrated approach might be in terms of reduced delays to flights and passengers, more schedule reliability, and lower operating costs.
*With Professor Amedeo Odoni and Professors Dimitris Bertsimas and Georgia Perakis of the MIT Sloan School of Management

Professor Moshe Ben-Akiva
Capturing the Relationship between Motility, Mobility and Well-Being Using Smart Phones
Understanding and incorporating measures of travel well-being in transportation research is critical for the design and evaluation of policies aimed at enhancing well-being. In recent years several efforts have been made to quantify travelers’ subjective well-being using travelers’ self-reported state of happiness while participating in various activities or travel patterns. But, in line with Amartya Sen’s capability approach, we argue that the well-being of a person is derived not only from what a person actually does or is (i.e. a person’s achieved functionings) but also from his/her capabilities i.e. the feasible alternative forms of functionings that he/she could have achieved or could have been. So far, a very limited number of studies have been conducted specifically in the field of transportation to measure well-being of travelers derived from their potential of mobility (can be related to accessibility in  a broader sense) i.e. from motility. The limitations of conventional survey methods to collect uninterrupted and comprehensive information about the activities and travel spaces of people have primarily restricted the number of such studies. In this research, we propose to conduct surveys and measure mobility patterns using smart phone technology (enabled with GPS, GSM, Wi-Fi and accelerometer) which will overcome the limitations of conventional surveys and will assist in developing novel measures of well-being based on a traveler’s mobility potentials i.e. from motility. We anticipate that by providing travelers with feedback about their own travel choices and the travel choices of their peer group, we will be able to influence travelers to make conscious decisions which will ultimately contribute to enhancing their travel well-being and encourage them to shift towards more sustainable transport behavior. 

This research project builds upon an innovative smart phone application for activity travel survey and will develop an enhanced method for the measurement of travel well-being. The novel measures of well-being that we will develop using smart phone technology will provide innovative guidelines for transportation policy design and evaluation based on travel well-being. The techniques and findings will further be useful to researchers in several other fields due to the multi-disciplinary nature of the topic of well-being measurement and survey data collection using smart phone technology.

Professor Moshe Ben-Akiva
Collaborative Research on Travel Behavior Modeling and Traffic Simulation
This research project focuses on multimodal route choice models and the development of models for the joint choice of mode and route. A critical element of this model is the generation of the choice set, ie., the set of alternatives that a traveler is choosing from. The choice set generation process and eventual choice from a choice set need to take into account the daily activity schedule, attributes of the various modes and the multimodal routing options and characteristics of the traveler. Data for such models may be collected by logging the movements of individuals using smartphones equipped with GPS and other sensors. 

Professor Moshe Ben-Akiva
Key Decision Factors for Toll Road Usage by Trucks
This research attempts to better understand truck routing behavior in terms of the decision-making process and the factors that affect routing choices. In order to collect data on the decision-making process, a computerized survey was employed to collect exploratory background information and Stated Preferences (SP). During the first year, road-intercept interviews of truck drivers were conducted at three major corridors in North America, with 1121 valid SP observations. An experimental design will be conducted in the second year in which an experiment to collect routing data from truckers using in-vehicle GPS units will be developed. In this experiment, in addition to the GPS data, drivers will be asked to provide information about the trips they have made (e.g. schedule, contract terms etc.) and to respond to a stated preferences (SP) questionnaire, in which they will be presented with various scenarios of alternative routes that will be characterized by different attributes of travel times and distances, tolls and other factors.  

Professor Moshe Ben-Akiva*
Intelligent Analysis of Ubiquitous Data (Singapore Alliance for Research and Technology – SMART)
The ubiquity of technologies related to Networked Computing and Control (NCC) provides a range of new close-to-real-time data for urban mobility planning and management, as in the case of GPS/Wi-Fi/cell-id traces and smartcard usage. The challenge lies in capturing the relevant information to enable it for real-time control, improved user service, and long-term strategic planning.  The objective here is to apply pattern recognition tools to obtain information relevant to mobility and transportation, namely activity, path and mode taken. 
*With Chris Zegras of MIT's Department of Urban Studies and Planning

Professor Moshe Ben-Akiva* 
Smartphone based prompted recall surveys (Singapore Alliance for Research and Technology – SMART)
The ubiquity of technologies related to Networked Computing and Control (NCC) provides a range of new close-to-real-time data for urban mobility planning and management, as in the case of any data obtainable from Smartphone usage. We are implementing a broad data collection effort using smartphones matched with web-based surveying tools to infer household and firm activities, including mobility and location choices.
*With Chris Zegras of MIT's Department of Urban Studies and Planning

Professor Moshe Ben-Akiva
Web information retrieval to support transportation network prediction and planning (Singapore Alliance for Research and Technology – SMART)
This project utilizes the web as a predictor of mobility phenomena. The base approach involves planned special events (e.g. concerts, festivals, sports, etc.), since these events are clearly identifiable both in online resources and in terms of their impact. We apply information retrieval and extraction techniques to mine for relevant information from the web and analyze available mobility data. The main outcome is a prediction model that receives extracted features from the web and generates expected impacts given future events. 

Professor Moshe Ben-Akiva* 
Behavioral Models for Land Use, Mobility, Energy and Resource Uses (Singapore Alliance for Research and Technology – SMART)
To plan sustainable future urban mobility systems, we need a set of forecasting tools to help make well-informed, consistent assessments of future conditions under various scenarios. Behavioral models are at the heart of the approach. The objective is to develop state-of-the-art models to understand and forecast different behavioral rationales of households and firms. These models cover different time frames, including long-term models such as residential location and auto ownership, medium-term models of activity and travel choices, and short-term driving and pedestrian behavior models. 
* With Chris Zegras of MIT's Department of Urban Studies and Planning, Joseph Ferreira of the Department of Urban Studies and Planning, and Maya Abou-Zeid of CEE's ITS Lab.

Professor Moshe Ben-Akiva
Advanced computation and modeling for real-time traffic prediction applications (Singapore Alliance for Research and Technology – SMART)
We are designing a new traffic prediction tool for highly complex transport networks such as Singapore. Such software needs innovative architectural design and implementation with state-of-the-art parallel and distributed computing functionalities. These requirements raise computer science research challenges that have implications in the modeling of complex systems beyond the traffic prediction case (e.g. weather, environment, market modeling, etc.). The project is also developing an Integrated suite of behavior models for simulation-based real-time traffic prediction systems. Given the real-time constraint, such models need to be simple, efficient and accurate. The challenges implied include advanced transport modeling, mathematical optimization and computer science. 

Professor Moshe Ben-Akiva
Real-Time Model System for Network Management and Emergency Response (Singapore Alliance for Research and Technology – SMART)
Develop an Integrated suite of models to estimate the impact of alternative interventions and support the real-time deployment of such interventions to mitigate urban mobility problems as they occur on a daily basis. 

Professor Moshe Ben-Akiva
Integrated Simulation Platform: SimMobility (Singapore Alliance for Research and Technology – SMART)
Integrate and link together various mobility-sensitive behavioral models with state-of-the-art simulators to predict impacts of mobility demands on transportation networks, services and vehicular emissions.  Integration will make it possible to simulate the effects of a portfolio of technology, policy and investment options under alternative future scenarios. The platform will integrate different types of modeling into a coherent agent-based micro-simulation. The decision process of the agents will be modeled by an activity-based approach. This simulation will be linked with a range of networked computing and control technology-enabled mobility innovations. The project's research plan is to develop an agent based and activity-based, multimodal simulator with the ability to simulate Long-Term timeframe at a Macroscopic level, Medium-term timeframe at Mesoscopic level and Short-term timeframe at Microscopic level. The challenge on the software side is to develop a parallel & distributed simulation engine to integrate short, medium and long-term modeling capability of urban mobility. The simulation engine will be the heart of the overall framework which will handle the events generated in various parts of the software, responsible for message passing between the processes and distributing the load among various processes.  

Professor Moshe Ben-Akiva
Activity based travel demand models (Singapore Alliance for Research and Technology – SMART)
Develop an Integrated suite of activity-based behavior models for SimMobility, our integrated simulation platform. Such models will consider aspects like transport multi-modality, activities, needs and other typical mobility related choices (route choice, departure time, etc.). The focus will be at the medium-term level, i.e. mesoscopic simulation. The topic areas include transport modeling and behavioral econometrics. 

Assistant Professor Marta González
Characterizing Transit Disruptions through Buses
Historically, studies of bus networks are confined to a single bus route. In contrast, we will approach bus performance with a computational architecture that enables us to compare routes and systems across multiple cities seamlessly, bringing a new perspective to bus performance as a system. We will exploit transit agencies publicly available General Transit Feed Specification (GTFS) data and their live XML feeds of bus GPS coordinates. The GTFS files define every aspect of each transit agency’s service. It provides the latitude/longitude coordinate definitions of the routes and the routes stops through to the daily transit vehicle trip schedules. Impact: Altering service is a huge commitment; this analysis will help transit providers eliminate some of the risk and uncertainty. Ultimately, we hope that in building this robust, extensible analysis tool, we will shed light onto the fundamental dynamics of buses dynamics on the city scale. We will compare bus systems across cities and hopefully deduce statistical laws to improve the system.

Assistant Professor  Marta González 
Road Usage Patterns

Global communication through mobile phones and online activity is a massive phenomenon in urban centers around the entire planet. This generates petabytes of information that contains fingerprints of individual human activity from remote locations. To date, however, it is still missing the link to quantify the individual interaction with streets infrastructures at a city scale. The underlying mechanisms driving the observed traffic flows in modern cities are still less known due to the lack of reliable data and proper methodologies. In this project, we use mobile phone data and road network data to estimate the road usage patterns in the San Francisco Bay area. This finding enables us to locate the home neighborhoods of road users and find how drivers from a particular neighborhood use each road in the city. Impact: We expect to learn more properties of the road networks determined by properties based on their usage and to extend the analysis to several cities. This finding will provide an alternative to the expensive travel diaries that only few cities in the world can afford. Our aim is to capture the relation of roads the population of each small zone within a city uses in daily trips. The information is of paramount importance to plan alternative transportation solutions based on group sharing, such as car sharing alternatives (see Zipcar.com) or ride sharing options (see GoLoco.org).

 Assistant Professor Carolina Osorio
Simulation-based Optimization Methods for Urban Traffic Management
Microscopic traffic simulators are popular tools used in practice to evaluate the performance of a set of pre-determined traffic management strategies. For a given strategy, they can provide accurate and detailed performance estimates. This project develops computationally efficient simulation-based optimization frameworks that enable the use of microscopic traffic simulation models to go beyond scenario-based analysis, and to devise suitable traffic management strategies. It enables the traffic simulation community to expand the use and purpose of these, costly to develop and evaluate, simulation models.

Professor Joseph Sussman
High-Speed Rail in Portugal
Professor Sussman and his research group are working on high-speed rail issues with universities in Portugal and RAVE (The Portuguese HSR agency). This research, aimed to assist the Portuguese in strategic questions regarding this major infrastructure investment. Research includes development of new methods of analysis (Multi-Attribute Tradespace Exploration or MATE), financing considerations, megaregion potential and the associated economic development opportunities, air/high-speed rail competition and and cooperation, and the possibility of using the high-speed rail network for international freight transportation.

Professor Joseph Sussman
Regional Transportation Strategy Development

This research aims to develop innovative methods for regional transportation strategy development using the nation of Portugal as a focal point through the MIT-Portugal Program. Researchers will consider both a multimodal transportation perspective and intermodal opportunities; the interface of urban with intercity transportation; and new technologies that can provide unconventional data for use in the regional transportation strategy process. Promising ways of innovating in strategy development include such procedures as scenario analysis, life-cycle costing and the CLIOS Process, a method for studying complex, large-scale, interconnected, open, sociotechnical (CLIOS) systems.
We will also link this research with other aspects of broad-based engineering systems, including consideration of real options, flexibility and stakeholder analysis.

Professor Nigel Wilson
Public Transportation Planning and Operations in London

London's century-old public transport system is undergoing more than $40 billion worth of renovation and expansion while facing major financial and capacity pressures. Our collaborative research program with Transport for London (TfL) focuses on the use of automatically collected data systems in strategic decision-making. Origin-destination matrices estimated based on data collected from the Oyster smart card ticketing system, as well as path choice models estimated from onboard surveys, will yield drastically improved, cheaper and more timely estimates of volumes and crowding on the London Underground and bus networks. Estimation of interchange behavior and multimodal journey patterns will aid in integrated network design. Methods are being developed to use end-to-end journey times, also measured by the Oyster system, to quantify the delays and unreliability experienced by passengers on London's rail networks. Rail signaling information will be used to evaluate and improve day-to-day service control decisions. A parallel focus of our work with TfL is to examine the technology and policy requirements for using commercial contactless credit cards for ticketing, as well as the effects of such a system on fare policy. Finally, we are investigating the use of innovative strategies and structures for the finance and delivery of large rail infrastructure projects, including Crossrail. 

Professor Nigel Wilson
Planning for Boston’s Green Line (Light Rail) Extension to Somerville and Me