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IEEE Annual Conference on Decision and Control

作者： Qingqing Huang Mardavij Roozbehani Munther A. Dahleh LIDS Laboratory for Information and Decision Systems (LIDS) Massachusetts Institute of Technology (MIT) Electrical Engineering and Computer Science (EECS) at MIT

ISBN: (纸本)9781467320658

In this paper, we examine in an abstract framework, how a tradeoff between efficiency and risk arises in different dynamic oligopolistic market architectures. We consider a market in which there is a monopolistic resource provider and agents that enter and exit the market following a random process. Self-interested and fully rational agents dynamically update their resource consumption decisions over a finite time horizon, under the constraint that the total resource consumption requirements are met before each individual's deadline. We then compare the statistics of the stationary aggregate demand processes induced by the non-cooperative and cooperative load scheduling schemes. We show that although the non-cooperative load scheduling scheme leads to an efficiency loss - widely known as the "price of anarchy" - the stationary distribution of the corresponding aggregate demand process has a smaller tail. This tail, which corresponds to rare and undesirable demand spikes, is important in many applications of interest. On the other hand, when the agents can cooperate with each other in optimizing their total cost, a higher market efficiency is achieved at the cost of a higher probability of demand spikes. We thus posit that the origins of endogenous risk in such systems may lie in the market architecture, which is an inherent characteristic of the system.

关键词： power markets tradeoffs Agents load dispatching Stochastic Processes oligopoly Resource utilization origins

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Machine learning with operational costs

The Journal of Machine Learning Research

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The Journal of Machine Learning Research 2013年第1期14卷

作者： Kevin Murphy Bernhard Schölkopf Theja Tulabandhula Cynthia Rudin Google MPI for Intelligent Systems Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA MIT Sloan School of Management and Operations Research Center Massachusetts Institute of Technology Cambridge MA

This work proposes a way to align statistical modeling with decision making. We provide a method that propagates the uncertainty in predictive modeling to the uncertainty in operational cost, where operational cost is the amount spent by the practitioner in solving the problem. The method allows us to explore the range of operational costs associated with the set of reasonable statistical models, so as to provide a useful way for practitioners to understand uncertainty. To do this, the operational cost is cast as a regularization term in a learning algorithm's objective function, allowing either an optimistic or pessimistic view of possible costs, depending on the regularization parameter. From another perspective, if we have prior knowledge about the operational cost, for instance that it should be low, this knowledge can help to restrict the hypothesis space, and can help with generalization. We provide a theoretical generalization bound for this scenario. We also show that learning with operational costs is related to robust optimization.

关键词： covering numbers decision theory optimization statistical learning theory

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Investigating GaSb(001) dry etching by ICP-RIE on a non-silicon containing sample holder with no organic gases

Investigating GaSb(001) dry etching by ICP-RIE on a non-sili...

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2011 MRS Fall Meeting

作者： Albrithen, Hamad A. Petrich, Gale S. Kolodziejski, Leslie A. Salhi, Abdelmajid Almuhanna, Abdulrahman A. Physics and Astronomy KAIN King Saud University Riyadh Riyadh Saudi Arabia Research Laboratory of Electronics MIT Cambridge MA United States Department of Electrical Engineering and Computer Science MIT Cambridge MA United States National Center for Nano Technology Research King Abdulaziz City for Science and Technology Riyadh Riyadh Saudi Arabia

ISBN: (纸本)9781605113739

We report the dry etch of GaSb(001) by inductively coupled plasma reactive ion etcher. Silicon Oxide, deposited by PECVD, was used as a mask. The oxide layer proved to be almost unaffected compared to the GaSb, when using chlorine compound gases as etchants (Cl2, BCl3, and SiCl 4) as well as argon. This provides high selectivity for GaSb to the mask layer. The sample holder has no silicon that may contribute to the etching process. Etching using Cl2 + Ar showed increase in the etching rate as the chlorine ratio increases;however, the process led to grassy surface and chemical like reaction. The use of SiCl4+Cl2+Ar mixture with low chlorine ratio resulted in anisotropic etch with smooth sides. It has been found for this case that the increase of the chlorine ratio led to an increased etching rate as well. The repeat of previously reported result by Swaminathan et al. [Thin Solid Films 516 (2008) 8712.] yet with a sample holder not having silicon, proved the effect of Si-contribution in producing vertical profile etch with smooth surfaces. © 2012 Materials Research Society.

关键词： Chlorine compounds

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Combining and optimizing NIRS and EEG to study interictal epileptic discharges

Combining and optimizing NIRS and EEG to study interictal ep...

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Biomedical Optics, BIOMED 2012

作者： Cooper, Robert J Yucel, Meryem Gagnon, Louis Suzuki, Nao Tanaka, Naoaki Reinsberger, Claus Boas, David A. Stufflebeam, Steve Athinoula A. Martinos Center for Biomedical Imaging Massachusetts General Hospital Charlestown MA United States Department of Electrical Engineering and Computer Science MIT Cambridge MA United States Department of Neurology Brigham and Women's Hospital Boston MA United States

We describe our ongoing application of NIRS-EEG to the study of inter-ictal discharges in adult epilepsy. We discuss optimizing NIRS-EEG data acquisition and analysis and we present preliminary NIRS-EEG results for an... 详细信息

ISBN: (纸本)9781557529428

关键词： Data acquisition

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Studies on the Formation and Evolution of Polar Cap Ionization Patches

Studies on the Formation and Evolution of Polar Cap Ionizati...

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中国物理学会2013年秋季学术会议

作者： Qing-He Zhang Bei-Chen Zhang Michael Lockwood Jφran Moen J.Michael Ruohoniemi Evan G.Thomas Shun-Rong Zhang Rui-Yuan Liu Mark Lester Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment School of Space Science and Physics Shandong University at Weihai Shandong China SOA Key Laboratory for Polar Science Polar Research Institute of China Shanghai China SOA Key Laboratory for Polar Science Polar Research Institute of China Shanghai China Department of Meteorology University of Reading Earley Gate P.O. Box 243 RG6 6BB UK Department of Physics University of Oslo Blindern Oslo Norway Bradley Department of Electrical & Computer Engineering Virginia Tech Blacksburg VA USA MIT Haystack Observatory Westford MA 01886 USA Department of physics and Astronomy University of Leicester Leicester UK

Patches of ionization are common in the polar ionosphere where their motion and associated density gradients give variable disturbances to High Frequency (HF) radio communications,over-the-horizon radar location error... 详细信息

关键词： Polar Ionoshpere polar cap patches “tongue” of ionization (TOI) magnetic reconnection

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Issues Faced in a Remote Instrumentation Laboratory

Issues Faced in a Remote Instrumentation Laboratory

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International Workshop on Technology for Education, T4E

作者： Shreya Malani G.N. Srinivasa Prasanna Jesus A. del Alamo James L. Hardison Kannan Moudgalya Venkatesh Chopella Computer Science Department IIIT Bangalore India Department of Computer Science and Electrical Engineering MIT Cambridge MA USA Department of Chemical Engineering IIT Mumbai India International Institute of Information Technology Hyderabad India

An Online Lab is a multi-university shared laboratory environment, where students can exercise their knowledge as they would do in a physical lab. The idea is to have maximum resource utilization and collaboration between universities by sharing of ideas. This kind of remote laboratory negates the economic issues to set up a laboratory and allows every student to have an experience of real laboratory. As part of Ministry of Human Resource Development (MHRD) Robotics Lab project a study on state of art of remote labs was conducted. This paper discusses some key issues in the design and operation of such remote labs. The lab should be remotely usable by a large student body, with varied levels of sophistication, all the way from elementary learners, to PhD students doing research. In addition, the high design load implies that the architecture should be highly parallel, and structurally reliable.

关键词： Hardware Robots Educational institutions Instruments Logic gates Remote laboratories

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Online map-matching based on Hidden Markov model for real-time traffic sensing applications

Online map-matching based on Hidden Markov model for real-ti...

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International IEEE Conference on Intelligent Transportation Systems

作者： C. Y. Goh J. Dauwels N. mitrovic M. T. Asif A. Oran P. Jaillet School of Electrical and Electronic Engineering Nanyang Technological University Center for Future Urban Mobility Singapore-MIT Alliance for Research and Technology (SMART) Laboratory for Information and Decision Systems Department of Electrical Engineering and Computer Science and Operations Research Center MIT

ISBN: (纸本)9781467330640

In many Intelligent Transportation System (ITS) applications that crowd-source data from probe vehicles, a crucial step is to accurately map the GPS trajectories to the road network in real time. This process, known as map-matching, often needs to account for noise and sparseness of the data because (1) highly precise GPS traces are rarely available, and (2) dense trajectories are costly for live transmission and storage. We propose an online map-matching algorithm based on the Hidden Markov Model (HMM) that is robust to noise and sparseness. We focused on two improvements over existing HMM-based algorithms: (1) the use of an optimal localizing strategy, the variable sliding window (VSW) method, that guarantees the online solution quality under uncertain future inputs, and (2) the novel combination of spatial, temporal and topological information using machine learning. We evaluated the accuracy of our algorithm using field test data collected on bus routes covering urban and rural areas. Furthermore, we also investigated the relationships between accuracy and output delays in processing live input streams. In our tests on field test data, VSW outperformed the traditional localizing method in terms of both accuracy and output delay. Our results suggest that it is viable for low-latency applications such as traffic sensing.

关键词： Hidden Markov models Intelligent transportation systems bus routes Probe vehicles real-time traffic road network field experimentation Noise

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A Near-Optimal Sublinear-Time Algorithm for Approximating the Minimum Vertex Cover Size 12

A Near-Optimal Sublinear-Time Algorithm for Approximating th...

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Annual ACM-Society for Industrial and Applied Mathmatics Symposium on Discrete Algorithms

作者： Krzysztof Onak Dana Ron Michal Rosen Ronitt Rubinfeld School of Computer Science Carnegie Mellon University School of Electrical Engineering Tel Aviv University Blavatnik School of Computer Science Tel Aviv University CSAIL MIT Cambridge MA 02139 and the Blavatnik School of Computer Science Tel Aviv University

ISBN: (纸本)9781611972108

We give a nearly optimal sublinear-time algorithm for approximating the size of a minimum vertex cover in a graph G. The algorithm may query the degree deg(v) of any vertex v of its choice, and for each 1 ≤ i ≤ deg(v), it may ask for the ith neighbor of v. Letting VC_(opt)(G) denote the minimum size of vertex cover in G, the algorithm outputs, with high constant success probability, an estimate VC(G) such that VC_(opt)(G) ≤ VC(G) ≤ 2VC_(opt)(G) + εn, where ε is a given additive approximation parameter. We refer to such an estimate as a (2, ε)-estimate. The query complexity and running time of the algorithm are O(d · poly(1/ε)), where d denotes the average vertex degree in the graph. The best previously known sublinear algorithm, of Yoshida et al. (STOC 2009), has query complexity and running time O(d~4/∈~2), where d is the maximum degree in the graph. Given the lower bound of Ω(d) (for constant ε) for obtaining such an estimate (with any constant multiplicative factor) due to Parnas and Ron (TCS 2007), our result is nearly optimal.

关键词： vertex head corners algorithms Runtime minimum dimension vectorcardiogram Line graph

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Direct numerical simulation of electroconvective instability and hysteretic current-voltage response of a permselective membrane

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Physical Review E 2012年第4期86卷 046310-046310页

作者： Van Sang Pham Zirui Li Kian Meng Lim Jacob K. White Jongyoon Han Singapore-MIT Alliance National University of Singapore Singapore College of Mechanical and Electrical Engineering Wenzhou University China Singapore-MIT Alliance for Research and Technology (SMART) Centre Singapore Department of Mechanical Engineering National University of Singapore Singapore Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA Department of Biological Engineering Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA

We present a systematic, multiscale, fully detailed numerical modeling for dynamics of fluid flow and ion transport covering Ohmic, limiting, and overlimiting current regimes in conductance of ion-selective membrane. By numerically solving the Poisson-Nernst-Planck-Navier-Stokes equations, it is demonstrated that the electroconvective instability, arising from the electric field acting upon the extended space charge layer, and the induced strong vortical fluid flow are the dominant factors of the overlimiting current in the planar membrane system. More importantly, at the transition between the limiting and the overlimiting current regimes, hysteresis of electric current is identified. The hysteresis demonstrates the important role of the electroconvective flow in enhancing of current in electrolyte systems with ion-selective membrane.

关键词： Numerical models

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High-order harmonic generation in Xe, Kr, and Ar driven by a 2.1-μm source: High-order harmonic spectroscopy under macroscopic effects

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Physical Review A 2012年第4期86卷 043412-043412页

作者： Kyung-Han Hong Chien-Jen Lai Vasileios-Marios Gkortsas Shu-Wei Huang Jeffrey Moses Eduardo Granados Siddharth Bhardwaj Franz X. Kärtner Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics Massachusetts Institute of Technology (MIT) Cambridge Massachusetts 02139 USA IKERBASQUE Basque Foundation for Science Spain Center for Free-Electron Laser Science DESY and Department of Physics Hamburg University Notkestraße 85 D-22607 Hamburg Germany

We experimentally and numerically study the atomic response and pulse propagation effects of high-order harmonics generated in Xe, Kr, and Ar driven by a 2.1-μm infrared femtosecond light source. The light source is an optical parametric chirped-pulse amplifier, and a modified strong-field approximation and three-dimensional pulse propagation code are used for the numerical simulations. The extended cutoff in the long-wavelength-driven high-order harmonic generation has revealed the spectral shaping of high-order harmonics due to the atomic structure (or photorecombination cross section) and the macroscopic effects, which are the main factors of determining the conversion efficiency besides the driving wavelength. Using precise numerical simulations to determine the macroscopic electron wave packet, we are able to extract the photorecombination cross sections from experimental high-order harmonic spectra in the presence of macroscopic effects. We have experimentally observed that the macroscopic effects shift the observed Cooper minimum of Kr from 80 eV to 60–70 eV and wash out the Cooper minimum of Ar. Measured high-harmonic conversion efficiencies per harmonic near the cutoff are ∼10−9 for all three gases.

关键词： Conversion efficiency

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