"I came into MIT with a music background and learned over the first few years I was there how to be an engineer, how to think like an engineer," Jean Sack, a member of the technical staff in MIT Lincoln Laboratory's Energy Systems Group, explained to a CNN reporter. CNN featured Sack on "The Next List" in 2013 for her innovation as a mechanical engineering undergraduate working at the Beaver Works Center in Cambridge, Massachusetts. She had headed a 28-student team tasked with developing an underwater power system as part of a Beaver Works capstone project. During her graduate studies, Sack went on to volunteer as a teaching assistant in a follow-on capstone course offered by the MIT Department of Mechanical Engineering (MechE). Exemplifying the Beaver Works philosophy that student engagement in collaborative, real-world-inspired projects fosters innovation, Sack has continued to build upon her milestone experience since joining the MIT Lincoln Laboratory last July. Sack's interest in renewable energy extends as far back as her unique upbringing in northern California. "Our house was powered entirely by photovoltaic cells with rain water collection for drinking water," she says of the house that her parents built in which to raise her and her brother. Now, renewable energy provides a means to help bring about global change. "I see climate change as the most critical issue facing the world, and as our methods for energy production of all types have put us here, our only hope is to phase out carbon-emitting power as soon as possible." A collaborative capstone project at Beaver Works allowed Sack to pursue her passion for alternative energy, while growing her perspective as an engineer. Professor Douglas Hart of MechE taught the class that Sack managed, and he described it as being run like a startup company: the professor acts as a technical advisor, allowing the students to take control of the project at hand. Sack considered the capstone projects to be the most rewarding technical courses offered at MIT because the students were able to apply the knowledge they had learned in other courses to advance current technology. "I started working with Beaver Works the spring term of my junior year at the encouragement of some of my teammates from the rowing team," says Sack, who enjoyed the opportunities for creative problem solving that the course offered. After that semester, Hart asked if Sack would be willing to serve as the student CEO for the next term. "Working with Professor Hart taught me how to stand up for myself and present competently, and dramatically increased my self-confidence and willingness to jump into a project when I had no idea where it would go," she says. Nicholas Pulsone, senior staff in the Advanced Undersea Systems and Technology Group, along with several other laboratory staff, had been collaborating with Hart for two years on the project in which Sack's team played an important role. The team was tasked with developing a new power system for the REMUS 600 that would extend this unmanned underwater vehicle's range to the point where it could be used to access any port in the world from U.S. military bases. Using MIT student Jonathan Slocum's innovative aluminum fuel, the team designed a system that would utilize the reactivity of aluminum with water, effectively eliminating the need for a million-dollar a day research ship. Now working at the laboratory for over half a year, Sack has become involved in a wide array of projects. "In her short time in the Energy Systems Group, Jean has contributed across a number of programs, including those in undersea power systems and soldier power applications," says Scott Van Broekhoven, leader of this group. "Jean has also helped to mentor the existing year's students in the development of a power source to extend soldier endurance." This current capstone project, which focuses on developing novel energy technologies to alleviate the logistics burden on the U.S. Marine Corps, has provided a platform for Sack to guide MIT students using her experience from her own capstone. "Whenever I hear Jean describe her work as a student, project CEO, and teaching assistant in a Beaver Works capstone course, it brings a smile to my face," says Robert Shin, head of the Intelligence, Surveillance, and Recfonnaissance and Tactical Systems Division and director of Beaver Works, who personally recommended Sack for her current position after seeing her performance at Beaver Works. "Beaver Works provides transformational experiences for many MIT students, and you only have to talk to Jean to understand how project-based learning changes a student's perspective on engineering. And, of course, I am thrilled to have Jean working at the laboratory, and I hope Beaver Works helps us discover many more such talented, engaged future staff members."
Natural systems such as grasslands form clusters, or patches, that bolster resilience under stress. Experiments show this same behavior can be modeled in bacteria with several important implications for creating survivable environments for threatened or endangered species, MIT researchers have reported online in Nature Microbiology. Populations of the commonly studied soil bacteria Bacillus subtilis survive at much lower cell density when they form patches than when they are more evenly spread out in their environment, says Jeff Gore, the Latham Family Career Development Associate Professor of Physics. This patchy growth is sufficient by itself to enhance survival prospects, but it also reduces expansion. In a resource-rich environment, mobility of the population is important because it leads to greater expansion, but in a resource-poor environment, keeping the population close together enables cooperative behavior to survive on sparse resources, Gore explains. These findings are relevant for conservation of more complex communities because they identify ways to enable population survival, in particular tailoring interventions to the environment. B. subtilis, a gram positive bacteria, needs sugar in glucose form to survive. They can get this sugar either directly from their environment or by collectively producing the amylase enzyme, which breaks down starch in their environment into sugars that the bacteria can consume. Christoph Ratzke, a postdoc in the Physics of Living Systems Group at MIT, and lead author of the paper, “Self-organized patchiness facilitates survival in a cooperatively growing Bacillus subtilis population,” studied the bacteria under both conditions. “He starts in a three-dimensional agar matrix where the cells are distributed uniformly. What he finds is if the population of cells is growing on a sugar like glucose that can be directly imported, then he sees that there is no patchiness. There is uniform growth throughout this three-dimensional volume,” Gore explains. “Whereas when he is growing these bacterial populations on starch where they’re growing collectively, then what he sees is the spontaneous self-organized emergence of patchy growth, where in some regions you get growth, in some regions, you don’t.” In order to rule out other significant contributors to these patches forming, the researchers conducted the same tests with genetically defective bacteria that lacked the ability to sense the richer food source or that couldn’t swim. In the absence of swimming ability and sensing ability, patches still formed, the experiments showed. The researchers also compared well-mixed environments where food and bacteria were evenly distributed by shaking to “spatial environments” where bacteria were allowed to spatially self-organize. Below the critical concentration, the bacteria die. Cell counts below the critical threshold for survival in a mixed environment were found to survive through clustering in the spatial environment. “There was a very big difference in terms of the density of the cells that were required for the survival. It required a much higher cell density in the well-mixed condition than in the spatial environment,” Gore explains. In the experiments, the researchers were able to control bacterial movement in the agar growth medium by controlling the density of the agar. Results showed a tradeoff between survival and rate of population expansion. “If the population is starting at high cell density, then what is best for the population is to be in a high mobility regime, that is the low agar concentration, because then the population can expand very rapidly. However, if the population is at low cell density, it’s actually better to be in high agar concentrations with low mobility. That actually facilitates the formation of the patches,” Gore says. “Because at higher agar concentration, where the bacteria are not able to swim as well, they can form very compact patches in which they can really grow cooperatively very well, and they can survive starting from very low cell density, but then once they have grown up, the patches are unable to expand very well just because they can’t swim very well,” he says. “The most interesting aspect of this work is self-organized patch formation among cooperative cells, which was unexpected,” says Wenying Shou, who was not involved in the research. “The formation of these patches was driven by cell heterogeneity, local cooperation, and global inhibition, thus making these patterns Turing patterns.” Shou, who studies evolution of cooperation and microbial communities at the Fred Hutchinson Cancer Research Center in Seattle, notes that disease-causing bacteria that are known to engage in cooperation also could enhance their survival by using spontaneous patch formation. Gore’s prior work examined the competition between cheaters and cooperators in budding yeast that secrete an enzyme that breaks down sucrose, a smaller and less complicated molecule than starch. The cooperators contribute to the public good by secreting the enzyme, whereas the cheaters don’t contribute to the public good and instead simply consume the glucose created by the cooperators. “What we found is that a cheater strain could spread in the population, but that we got coexistence between the producers and the non-producers, between the cooperators and the cheaters,” Gore explains. Ratzke next will focus on similar studies of producers and non-producers in B. subtilis bacteria. “Similar dynamics could take place even between species,” Gore says. “You could have this B. subtilis species interacting with another species that doesn’t produce amylase, and they may have similar dynamics. This is pointing to some potentially, I think, really deep similarities between evolution and ecology. That you could have evolution within a species, or you could have ecological dynamics between species, and you could get rather similar phenomena.”
Wang W.,Systems Group |
Liang S.,University of Maryland University College
IEEE Geoscience and Remote Sensing Letters | Year: 2010
This letter presents new models for estimating clear-sky instantaneous longwave radiation over land surfaces using the Geostationary Operational Environmental Satellites (GOES) Sounders and GOES-R Advanced Baseline Imager (ABI) thermal infrared top-of-atmosphere (TOA) radiances. The method used in this study shares the same hybrid method framework designed for Moderate Resolution Imaging Spectroradiometer. We propose separate surface downward longwave radiation (LWDN) and upwelling longwave radiation (LWUP) models because the two components are dominated by different surface/atmospheric properties. A nonlinear model was developed to estimate LWDN, and a linear model was developed to estimate LWUP. The GOES-12 Sounder-derived LWDN, LWUP, and surface net longwave radiation (LWNT = LWUP-LWDN) were evaluated using one full-year of ground data from the Surface Radiation Budget Network. The root-mean-squared errors (rmses) are less than 22.03 W/m2 at all four sites. Our study indicates that the hybrid method can also be applied to estimate LWUP using the future GOES-R ABI TOA radiances. The lack of a channel beyond 13.3 μm in the proposed ABI design may cause larger rmses when estimating LWDN. © 2006 IEEE. Source
« New BMW Brilliance engine plant with light metal foundry in China; high-voltage battery production to come | Main | Nissan announces UK production for future generation EV batteries » Orbital ATK successfully tested a 3D-printed hypersonic engine combustor at NASA Langley Research Center. The combustor, produced through an additive manufacturing process known as powder bed fusion (PBF), was subjected to a variety of high-temperature hypersonic flight conditions over the course of 20 days, including one of the longest duration propulsion wind tunnel tests ever recorded for a unit of this kind. Analysis confirms the unit met or exceeded all of the test requirements. One of the most challenging parts of the propulsion system, a scramjet combustor, houses and maintains stable combustion within an extremely volatile environment. The tests were, in part, to ensure that the PBF-produced part would be robust enough to meet mission objectives. Additive manufacturing opens up new possibilities for our designers and engineers. This combustor is a great example of a component that was impossible to build just a few years ago. This successful test will encourage our engineers to continue to explore new designs and use these innovative tools to lower costs and decrease manufacturing time. —Pat Nolan, Vice President and General Manager of Orbital ATK’s Missile Products division of the Defense Systems Group The test at Langley was an important opportunity to challenge Orbital ATK’s new combustor design, made possible only through the additive manufacturing process. Complex geometries and assemblies that once required multiple components can be simplified to a single, more cost-effective assembly. However, since the components are built one layer at a time, it is now possible to design features and integrated components that could not be easily cast or otherwise machined. PBF is one of several manufacturing methods currently being explored by Orbital ATK and its technology partners. Final assembly of the test combustor was completed at the company’s facilities in Ronkonkoma, New York, and Allegany Ballistics Laboratory in Rocket Center, West Virginia.
A few years ago, a team of nutritionists from Tufts University who had been experimenting with mobile-phone apps for recording caloric intake approached members of the Spoken Language Systems Group at MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL), with the idea of a spoken-language application that would make meal logging even easier. This week, at the International Conference on Acoustics, Speech, and Signal Processing in Shanghai, the MIT researchers are presenting a Web-based prototype of their speech-controlled nutrition-logging system. With it, the user verbally describes the contents of a meal, and the system parses the description and automatically retrieves the pertinent nutritional data from an online database maintained by the U.S. Department of Agriculture (USDA). The data is displayed together with images of the corresponding foods and pull-down menus that allow the user to refine their descriptions—selecting, for instance, precise quantities of food. But those refinements can also be made verbally. A user who begins by saying, "For breakfast, I had a bowl of oatmeal, bananas, and a glass of orange juice" can then make the amendment, "I had half a banana," and the system will update the data it displays about bananas while leaving the rest unchanged. "What [the Tufts nutritionists] have experienced is that the apps that were out there to help people try to log meals tended to be a little tedious, and therefore people didn't keep up with them," says James Glass, a senior research scientist at CSAIL, who leads the Spoken Language Systems Group. "So they were looking for ways that were accurate and easy to input information." The first author on the new paper is Mandy Korpusik, an MIT graduate student in electrical engineering and computer science. She's joined by Glass, who's her thesis advisor; her fellow graduate student Michael Price; and by Calvin Huang, an undergraduate researcher in Glass's group. In the paper, the researchers report the results of experiments with a speech-recognition system that they developed specifically to handle food-related terminology. But that wasn't the main focus of their work; indeed, an online demo of their meal-logging system instead uses Google's free speech-recognition app. Their research concentrated on two other problems. One is identifying words' functional role: The system needs to recognize that if the user records the phrase "bowl of oatmeal," nutritional information on oatmeal is pertinent, but if the phrase is "oatmeal cookie," it's not. The other problem is reconciling the user's phrasing with the entries in the USDA database. For instance, the USDA data on oatmeal is recorded under the heading "oats"; the word "oatmeal" shows up nowhere in the entry. To address the first problem, the researchers used machine learning. Through the Amazon Mechanical Turk crowdsourcing platform, they recruited workers who simply described what they'd eaten at recent meals, then labeled the pertinent words in the description as names of foods, quantities, brand names, or modifiers of the food names. In "bowl of oatmeal," "bowl" is a quantity and "oatmeal" is a food, but in "oatmeal cookie," oatmeal is a modifier. Once they had roughly 10,000 labeled meal descriptions, the researchers used machine-learning algorithms to find patterns in the syntactic relationships between words that would identify their functional roles. To translate between users' descriptions and the labels in the USDA database, the researchers used an open-source database called Freebase, which has entries on more than 8,000 common food items, many of which include synonyms. Where synonyms were lacking, they again recruited Mechanical Turk workers to supply them. The version of the system presented at the conference is intended chiefly to demonstrate the viability of its approach to natural-language processing; it reports calorie counts but doesn't yet total them automatically. A version that does is in the works, however, and when it's complete, the Tufts researchers plan to conduct a user study to determine whether it indeed makes nutrition logging easier. "I think logging is enormously helpful for many people," says Susan Roberts, director of the Energy Metabolism Lab at Tufts' USDA-sponsored Jean Mayer Human Nutrition Research Center on Aging. "It makes people more self-aware about the junk they are eating and how little they actually enjoy it, and the shock of huge portions, et cetera. But currently, it is really tedious to log your food. There are any number of programs like MyFitnessPal where you can manually enter it by hand, but even with shortcuts it is tedious and not as user friendly as it needs to be for millions of people to use it really regularly." "A spoken-language system that you can use with your phone would allow people to log food wherever they are eating it, with less work," she adds. "As I see it, we need to come up with something that really isn't much work, so it isn't an extra burden in life."