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Caltech Authors (144.724 recursos)

Repository of works by Caltech published authors.

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Mostrando recursos 1 - 20 de 702

  1. Osiris: A Tool for Abstraction and Verification of Control Software with Lookup Tables

    Aréchiga, Nikos; Dathathri, Sumanth; Vernekar, Shashank; Kathare, Nagesh; Gao, Sicun; Shiraishi, Shinichi
    Some industrial systems are difficult to formally verify due to their large scale. In particular, the widespread use of lookup tables in embedded systems across diverse industries, such as aeronautics and automotive systems, create a critical obstacle to the scalability of formal verification. This paper presents Osiris, a tool that automatically computes abstractions of lookup tables. Osiris uses these abstractions to verify a property in first order logic. If the verification fails, Osiris uses a falsification heuristic to search for a violation of the specification. We validate our technique on a public benchmark of an adaptive cruise controller with lookup...

  2. Data-Driven Ghosting using Deep Imitation Learning

    Le, Hoang M.; Carr, Peter; Yue, Yisong; Lucey, Patrick
    Current state-of-the-art sports metrics such as “Wins-above-Replacement” in baseball, “Expected Point Value” in basketball, and “Expected Goal Value” in soccer and hockey are now commonplace in performance analysis. These measures have enhanced our ability to compare and value performance in sport. But they are inherently limited because they are tied to a discrete outcome of a specific event. With the widespread (and growing) availability of player and ball tracking data comes the potential to quantitatively analyze and compare fine-grain movement patterns. An excellent example of this was the “ghosting” system developed by the Toronto Raptors to analyze player decision-making in...

  3. Feedback-Based Inhomogeneous Markov Chain Approach To Probabilistic Swarm Guidance

    Bandyopadhyay, Saptarshi; Chung, Soon-Jo; Hadaegh, Fred Y.
    This paper presents a novel and generic distributed swarm guidance algorithm using inhomogeneous Markov chains that guarantees superior performance over existing homogeneous Markov chain based algorithms, when the feedback of the current swarm distribution is available. The probabilistic swarm guidance using inhomogeneous Markov chain (PSG–IMC) algorithm guarantees sharper and faster convergence to the desired formation or unknown target distribution, minimizes the number of transitions for achieving and maintaining the formation even if the swarm is damaged or agents are added/removed from the swarm, and ensures that the agents settle down after the swarm’s objective is achieved. This PSG–IMC algorithm relies on a novel technique for constructing Markov matrices...

  4. Swarms of Femtosats for Synthetic Aperture Applications

    Chung, Soon-Jo; Hadaegh, F. Y.
    The Silicon Wafer Integrated Femtosatellites (SWIFT) Swarm Project presents a new paradigm-shifting definition of spacecraft technology that can enable flight of swarms of fully capable femtosats. One of the most important applications of SWIFT is a distributed aperture array. New swarm Golay array configurations are introduced and shown to dramatically increase the effective diameter derived from optical performance metrics. A system cost analysis based on this comparison justifies deploying a large number of spacecraft for sparse aperture applications.

  5. Mapping Coherent, Time-Varying Wavefronts from the Tohoku Tsunami into Enhanced, Time-Dependent Warning Messages

    Shi, J.; Kohler, M. D.; Sutton, J. N.; Ampuero, J.-P.
    Recent results are presented to illustrate how predictions of tsunami wave impact and tsunami warning mes-sages can be improved by including information about multiple, large-amplitude wave arrivals over longer time durations and at refined spatial resolution. A deployment of ocean bottom seismometers off the coast of southern California recorded the March 2011 Tohoku tsunami on 22 differential pressure gauges. The pressure gauge tsu-nami records across the entire array show multiple large-amplitude, coherent phases arriving one hour to more than 36 hours after the initial tsunami phase. Analysis of the pressure gauge recordings reveals possible locations of the geographical sources that...

  6. Dense Building Instrumentation Application for City-Wide Structural Health Monitoring

    Massari, A.; Kohler, M.; Clayton, R.; Guy, R.; Heaton, T.; Bunn, J.; Chandy, K. M.; Demetri, D.
    The Community Seismic Network (CSN) has partnered with the NASA Jet Propulsion Laboratory (JPL) to initiate a campus-wide structural monitoring program of all buildings on the premises. The JPL campus serves as a proxy for a densely instrumented urban city with localized vibration measurements collected throughout the free-field and built environment. Instrumenting the entire campus provides dense measurements in a horizontal geospatial sense for soil response; in addition five buildings have been instrumented on every floor of the structure. Each building has a unique structural system as well as varied amounts of structural information via structural drawings, making several levels...

  7. Why Is It That Europeans Ended Up Conquering the Rest of the Globe? Prices, the Military Revolution, and Western Europe’s Comparative Advantage in Violence

    Hoffman, Philip T.
    Preliminary data from England and France show that the relative price of artillery, handguns, and gunpowder declined between the fourteenth century and the eighteenth century. Prices fell relative to the cost of factors of production, and the price decline suggests that the military sector of western European economies experienced sustained technical change before the Industrial Revolution – a claim in accord with qualitative evidence from research on the late medieval and early modern military revolution. The price data shed new light on this revolution and point to a potential explanation for why western Europe developed a comparative advantage in violence over...

  8. Real-Time Optimal Control and Target Assignment for Autonomous In-Orbit Satellite Assembly from a Modular Heterogeneous Swarm

    Foust, Rebecca; Chung, Soon-Jo; Hadaegh, Fred Y.
    This paper presents a decentralized optimal guidance and control scheme to combine a heterogeneous swarm of component satellites, rods and connectors, into a large satellite structure. By expanding prior work on a decentralized auction algorithm with model predictive control using sequential convex programming (MPC-SCP) to allow for the limited type heterogeneity and docking ability required for in-orbit assembly. The assignment is performed using a distributed auction with a variable number of targets and strict bonding rules to address the heterogeneity. MPC-SCP is used to generate the collision-free trajectories, with modifications to the constraints to allow docking.

  9. Faster Constraint Solving Using Learning Based Abstractions

    Dathathri, Sumanth; Arechiga, Nikos; Gao, Sicun
    This work addresses the problem of scalable constraint solving. Our technique combines traditional constraint-solving approaches with machine learning techniques to propose abstractions that simplify the problem. First, we use a collection of heuristics to learn sets of constraints that may be well abstracted as a single, simpler constraint. Next, we use an asymmetric machine learning procedure to abstract the set of clauses, using satisfying and falsifying instances as training data. Next, we solve a reduced constraint problem to check that the learned formula is indeed a consequent (or antecedent) of the formula we sought to abstract, and finally we use the learned formula to check the original property. Our experiments...

  10. Eteaming With Developing Nations: Social Outreach With An Entrepreneurial Twist

    Blanco, Mario; Pickar, Kenneth; Delgado, Luz Marina; Kranski, Jeff; Arce, Oscar; Herrera, Francoise; MacVean, Charles
    The World Bank estimates that over 2.8 billion people live in poverty, earning less than $2/day. Financial assistance alone has not been able to solve the problems generated by poverty in a sustainable way. We are testing the hypothesis that the teaching of product design principles together with basic entrepreneurship skills might be a way to provide longer-lasting solutions. These ideas are based on the premise that although cash might be the most pressing need of the poor, the most vital need is the acquisition of income generation skills. Major challenges arose in the initial testing stage, from the formidable physical and cultural...

  11. Incorporating Scientific Analysis And Problem Solving Skills Into A Physics And Engineering Summer Course

    Franck, Jennifer; Yu, Ted; Ochoa-Ricoux, Juan Pedro; Maloney, James; Capece, Angela; Rivas, Luz
    The Young Engineering and Science Scholars (YESS) three-week summer program offered by the California Institute of Technology (Caltech) recruits and inspires talented high school students towards engineering and science career paths. The program is geared towards highachieving, but traditionally underrepresented minority students in science and engineering who have demonstrated excellent academic records in math and science. This paper describes the science and engineering course offered by the program including its objectives, teaching philosophies, and its mentoring process for design and research projects. Assessment is performed using the Force Concept Inventory (FCI) and shows excellent student gains when compared with other college-level physics courses. Student surveys and feedback on...

  12. Physics Fundamentals, Engineering Design, And Research: An Integrated Approach To The Development Of A Three Week Shortcourse

    Jackson, Winston; Franck, Jennifer; Maloney, James; Ochoa-Ricoux, Juan Pedro; Rimoli, Julian; Rivas, Luz
    Many outreach programs offered by universities provide pre-college students an opportunity to explore careers in science and engineering. For high-achieving students who already have an interest in these areas, these types of programs can introduce students to advanced concepts, develop their understanding of scientific methodologies, and expose them to science and engineering research. One such program, the Young Engineering and Science Scholars (YESS) Program, is a three-week summer residential program created to bring exceptional high school juniors and seniors from underrepresented minority groups to study at the California Institute of Technology (Caltech). The program is intended for motivated students who wish to broaden their knowledge of science and...

  13. Integrating Engineering, Modeling, And Computation Into The Biology Classroom: Development Of Multidisciplinary High School Neuroscience Curricula

    Gomez, Tara; Loson, Oliver; Yung, Douglas; Kadambi, Sindhuja; Lee, Paul; Rivas, Luz
    The YESS program is a three-week summer residential course that brings together extraordinarily talented high school students from underrepresented minority groups to study at the California Institute of Technology. The YESS program is intended for students who exhibit an interest in engineering and science, and wish to engage in collaborative learning. During the three-week program, students take science courses and are exposed to laboratory tours, faculty lectures, and college admissions workshops. The neuroscience course for the 2008 YESS program was an intensive survey of many different fields, and used lectures, demonstrations and laboratory activities to teach topics such as brain anatomy, Drosophila melanogaster pain perception, electrophysiology,...

  14. Enhancing K 12 Science And Engineering Through Sustainable Partnerships Between Scientists And Teachers

    Maloney, James; Gomez, Tara; Franck, Jennifer; Aschbacher, Pamela
    [no abstract]

  15. Photon, electron, and ion management in artificial photosynthesis: Realizing efficient and stable renewable energy to fuel conversion

    Sun, Ke; Lewis, Nathan S.
    Direct prodn. of fuels from sunlight, air (N_2 or CO_2), and water that can be stored, transported, and later converted into hydrogen or electricity to provide power for transportation and distributed energy generation, have received recent attentions worldwide. This technol. could also in principle provide chems. as synthetic precursors or realize grid-level storage of intermittent solar energy. In artificial photosynthesis based on semiconductor photoelectrochem., the prodn. of chem. fuels generally requires the coupling of semiconductors with electrocatalysts where elec. charges are generated, sepd. and transferred for multi-electron chem. reactions, as well as the pairing of light-absorbing materials with optimum bandgap...

  16. Two-Dimensional Sparse Arrays with Hole-Free Coarray and Reduced Mutual Coupling

    Liu, Chun-Lin; Vaidyanathan, P. P.
    Two-dimensional sparse arrays with hole-free difference coarrays, like billboard arrays and open box arrays, can identify O(N^2) uncorrelated source directions (DOA) using N sensors. These arrays contain some dense ULA segments, leading to many sensor pairs separated by λ/2. The DOA estimation performance often suffers degradation due to mutual coupling between such closely-spaced sensor pairs. This paper introduces a new 2D array called the half open box array. For a given N, this array has the same hole-free coarray as an open box array. At the same time, the number of sensor pairs with small separation is significantly reduced.

  17. Metal-oxos in chemistry and biology

    Gray, Harry B.
    The dianionic oxo ligand occupies a very special place in coordination chem., owing to its ability to donate pi electrons to stabilize high oxidn. states of metals. My papers on the ligand field theory of multiple bonding in metal-oxos were published over 50 years ago in the first vol. of Inorg. Chem. The theory, which accounts for the optical and EPR spectroscopic properties of these complexes, also predicts that there must be an "oxo wall" between Fe-Ru-Os and Co-Rh-Ir in the periodic table. There have been many attempts to break down the wall, but it is still in pretty good...

  18. Lederman's Shoulder, Weinberg's Nose, and Other Lessons from the Past

    Politzer, H. David
    [No abstract]

  19. Crystallization-driven ordering and self-assembly in bottlebrush polymers

    Kim, Joey; Hadjichristidis, Nikos; Kornfield, Julia A.
    The natural building blocks of linear polymer are monomers. Similarly, the natural building blocks of bottblebrush polymers are linear polymers (commonly referred to as polymacromonomers). It is well established that many properties of linear polymers can be tuned by using different copolymer systems. Similarly, we expect tunability of bottlebrush polymers by using chem. distinct polymer chains. A collaborative effort with Hadjichristidis from KAUST led us to a deeper study on the arrangement of chem. distinct polymeric units within the bottlebrush architecture. We have organized these samples into four categories based on the geometric connectivity: homo-bottlebrush polymer (H) in which all side chains have identical chem. functionality,...

  20. Why isn't noble gas chemistry 30 years older? The failed (?) 1933 experiment of Yost and Kaye

    Labinger, Jay
    The first report of a noble gas compd., by Neil Bartlett in 1962, was quickly followed by a no. of others. Of course there ha been previous attempts, of which the best documented is probably that of Caltech inorg. chem. professor Donald Yost and student Albert Kaye; details of their unsuccessful expts. aimed at getting xenon to react with fluorine or chlorine were publ in JACS in 1933. After Bartlett"s success, a no. of commentators looked back to Yost"s paper and offered a variety of poss reasons for Yost"s failure. Examn. of the actual details of Yost's paper, in comparison with those of the...

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