3,301 research outputs found

    Adaptive observers for nonlinearly parameterized systems subjected to parametric constraints

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    We consider the problem of adaptive observer design in the settings when the system is allowed to be nonlinear in the parameters, and furthermore they are to satisfy additional feasibility constraints. A solution to the problem is proposed that is based on the idea of universal observers and non-uniform small-gain theorem. The procedure is illustrated with an example.Comment: 19th IFAC World Congress on Automatic Control, 10869-10874, South Africa, Cape Town, 24th-29th August, 201

    Does afforestation deteriorate haze pollution in Beijing-Tianjin-Hebei (BTH), China?

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    Although aggressive emission control strategies have been implemented recently in the Beijing-Tianjin-Hebei area (BTH), China, pervasive and persistent haze still frequently engulfs the region during wintertime. Afforestation in BTH, primarily concentrated in the Taihang and Yan Mountains, has constituted one of the controversial factors exacerbating the haze pollution due to its slowdown of the surface wind speed. We report here an increasing trend of forest cover in BTH during 2001-2013 based on long-term satellite measurements and the impact of the afforestation on the fine-particle (PM2.5) level. Simulations using the Weather Research and Forecast model with chemistry reveal that afforestation in BTH since 2001 has generally been deteriorating the haze pollution in BTH to some degree, enhancing PM2.5 concentrations by up to 6% on average. Complete afforestation or deforestation in the Taihang and Yan Mountains would increase or decrease the PM2.5 level within 15% in BTH. Our model results also suggest that implementing a large ventilation corridor system would not be effective or beneficial to mitigate the haze pollution in Beijing

    Communication-Optimal Distributed Dynamic Graph Clustering

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    We consider the problem of clustering graph nodes over large-scale dynamic graphs, such as citation networks, images and web networks, when graph updates such as node/edge insertions/deletions are observed distributively. We propose communication-efficient algorithms for two well-established communication models namely the message passing and the blackboard models. Given a graph with nn nodes that is observed at ss remote sites over time [1,t][1,t], the two proposed algorithms have communication costs O~(ns)\tilde{O}(ns) and O~(n+s)\tilde{O}(n+s) (O~\tilde{O} hides a polylogarithmic factor), almost matching their lower bounds, Ω(ns)\Omega(ns) and Ω(n+s)\Omega(n+s), respectively, in the message passing and the blackboard models. More importantly, we prove that at each time point in [1,t][1,t] our algorithms generate clustering quality nearly as good as that of centralizing all updates up to that time and then applying a standard centralized clustering algorithm. We conducted extensive experiments on both synthetic and real-life datasets which confirmed the communication efficiency of our approach over baseline algorithms while achieving comparable clustering results.Comment: Accepted and to appear in AAAI'1

    Darboux transformation for two-level systems

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    We develop the Darboux procedure for the case of the two-level system. In particular, it is demonstrated that one can construct the Darboux intertwining operator that does not violate the specific structure of the equations of the two-level system, transforming only one real potential into another real potential. We apply the obtained Darboux transformation to known exact solutions of the two-level system. Thus, we find three classes of new solutions for the two-level system and the corresponding new potentials that allow such solutions.Comment: 10 page

    Reducing Youth Not in Employment, Education, or Training through JobStart Philippines

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    Key Points One in four young Filipinos are not in employment, education, or training. One in two young women with high school education or less are not in employment, education, or training. Creating wage jobs for the youth is critical to help reduce poverty and income inequality in the Philippines. Active labor market programs encourage employment creation and employability of workers, increase their earning capacity, and enhance integration into the productive workforce. In 2011, the Department of Labor and Employment (DOLE) of the Philippines collaborated with the Asian Development Bank (ADB) to design and develop JobStart Philippines, a pilot project assisting at-risk youth to become job-ready. JobStart Philippines is an employer-led program and offers at-risk youth life skills training, one-on-one career coaching, and opportunities for technical training and internships with private sector employers. Upon successful completion of the pilot, DOLE converted JobStart Philippines into a regular program and Congress enacted the Act to Institutionalize JobStart Philippines Program in 2016, which guarantees program sustainability

    Magnetoresistance of Two-Dimensional Fermions in a Random Magnetic Field

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    We perform a semiclassical calculation of the magnetoresistance of spinless two-dimensional fermions in a long-range correlated random magnetic field. In the regime relevant for the problem of the half filled Landau level the perturbative Born approximation fails and we develop a new method of solving the Boltzmann equation beyond the relaxation time approximation. In absence of interactions, electron density modulations, in-plane fields, and Fermi surface anisotropy we obtain a quadratic negative magnetoresistance in the weak field limit.Comment: 12 pages, Latex, no figures, Nordita repor

    Protein structures and optimal folding emerging from a geometrical variational principle

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    Novel numerical techniques, validated by an analysis of barnase and chymotrypsin inhibitor, are used to elucidate the paramount role played by the geometry of the protein backbone in steering the folding to the correct native state. It is found that, irrespective of the sequence, the native state of a protein has exceedingly large number of conformations with a given amount of structural overlap compared to other compact artificial backbones; moreover the conformational entropies of unrelated proteins of the same length are nearly equal at any given stage of folding. These results are suggestive of an extremality principle underlying protein evolution, which, in turn, is shown to be associated with the emergence of secondary structures.Comment: Revtex, 5 pages, 5 postscript figure

    Test Case Purification for Improving Fault Localization

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    Finding and fixing bugs are time-consuming activities in software development. Spectrum-based fault localization aims to identify the faulty position in source code based on the execution trace of test cases. Failing test cases and their assertions form test oracles for the failing behavior of the system under analysis. In this paper, we propose a novel concept of spectrum driven test case purification for improving fault localization. The goal of test case purification is to separate existing test cases into small fractions (called purified test cases) and to enhance the test oracles to further localize faults. Combining with an original fault localization technique (e.g., Tarantula), test case purification results in better ranking the program statements. Our experiments on 1800 faults in six open-source Java programs show that test case purification can effectively improve existing fault localization techniques
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