OpenRaiser/Intern-Atlas huggingface dataset:
Toward Using Surrogates to Accelerate Solution of Stochastic Electricity Grid Operations Problems
Venue: arXiv cs.SY 2014
Year: 2014

Stochastic unit commitment models typically handle uncertainties in forecast demand by considering a finite number of realizations from a stochastic process model for loads. Accurate evaluations of expectations or higher moments for the quantities of interest require a prohibitively large number of model evaluations. In this paper we propose an alternative approach based on using surrogate models valid over the range of the forecast uncertainty. We consider surrogate models based on Polynomial Chaos expansions, constructed using sparse quadrature methods. Considering expected generation cost, we demonstrate the approach can lead to several orders of magnitude reduction in computational cost relative to using Monte Carlo sampling on the original model, for a given target error threshold.
Multicore Homology via Mayer Vietoris
Venue: arXiv cs.CG 2014
Year: 2014

In this work we investigate the parallel computation of homology using the Mayer-Vietoris principle. We present a two stage approach for parallelizing persistence. In the first stage, we produce a cover of the input cell complex by overlapping subspaces. In the second stage, we use this cover to build the Mayer-Vietoris blowup complex, a topological space, which organizes the various subspaces needed for employing the Mayer-Vietoris principle. Next, we compute the homology of each subspace in the blowup complex in parallel and then glue these results together in serial. We show how to use the persistence algorithm to organize these computations. In the first stage, any algorithm can be used to produce a cover of the input complex. We describe an algorithm for producing a cover of a space with a simple structure and bounded overlap based on graph partitions. Additionally, we present a simplistic model for the problem of finding covers appropriate for parallel algorithms and show that finding such covers is NP-Hard. Finally, we present a second parallel homology algorithm. This algorithm avoids the explicit construction of the blowup complex saving space. We implement our algorithms for multicore computers, and compare them against each other as well as existing serial and parallel algorithms with a suite of experiments. We achieve roughly 8x speedup of the homology computations on a 10-dimensional complex with about 46 million simplices using 11 cores.
Cryptography from Quantum mechanical viewpoint
Venue: arXiv cs.CR 2014
Year: 2014

Cryptography is an art and science of secure communication. Here the sender and receiver are guaranteed the security through encryption of their data, with the help of a common key. Both the parties should agree on this key prior to communication. The cryptographic systems which perform these tasks are designed to keep the key secret while assuming that the algorithm used for encryption and decryption is public. Thus key exchange is a very sensitive issue. In modern cryptographic algorithms this security is based on the mathematical complexity of the algorithm. But quantum computation is expected to revolutionize computing paradigm in near future. This presents a challenge amongst the researchers to develop new cryptographic techniques that can survive the quantum computing era. This paper reviews the radical use of quantum mechanics for cryptography.
A Compact Model of Silicon-Based Nanowire Field Effect Transistor for Circuit Simulation and Design
Venue: arXiv cs.ET 2014
Year: 2014

As the conventional silicon metal-oxide-semiconductor field-effect transistor (MOSFET) approaches its scaling limits; many novel device structures are being extensively explored. Among them, the silicon nanowire transistor (SNWT) has attracted broad attention. To understand device physics in depth and to assess the performance limits of SNWTs, simulation is becoming increasingly important. The objectives of this work are: 1) to theoretically explore the essential physics of SNWTs (e.g., electrostatics, transport and band structure) by performing computer-based simulations, and 2) to assess the performance limits and scaling potentials of SNWTs and to address the SNWT design issues. The computer based simulations carried out are essentially based on DFT using NEGF formalism. A silicon nanowire has been modeled as PN diode (Zener Diode), PIN diode, PIP & NIN diode configurations by selectively doping the nanowire and simulated by biasing one end of the nanowire to ground and sweeping the other end of the nanowire from -1 V to 1 V to obtain the electrical characteristics of the respective diodes. In order to determine the effectiveness of the modeled diodes in silicon nanowire, the same diodes have been modeled using a germanium nanowire by selective doping and simulated in the same manner to obtain the electrical characteristics of the germanium nanowire based diodes which has been used as a reference to analyze the characteristics obtained using silicon nanowire. The modeled diodes are extremely small in dimension when compared to the conventional bulk silicon and germanium based diodes. This work is followed by modeling and simulation of a gate all around nanowire field effect transistor using two different gate dielectrics, followed by temperature dependence of the nanowire FET characteristics and the off state current and conductance variation using the two dielectrics.
Intelligent Fatigue Detection and Automatic Vehicle Control System
Venue: arXiv cs.OH 2014
Year: 2014

This paper describes method for detecting the early signs of fatigue in train drivers. As soon as the train driver is falling in symptoms of fatigue immediate message will be transfer to the control room indicating the status of the drivers. In addition of the advance technology of heart rate sensors is also added in the system for correct detection of status of driver if in either case driver is falling to fatigue due to any sever medical problems .The fatigue is detected in the system by the image processing method of comparing the image(frames) in the video and by using the human features we are able to estimate the indirect way of detecting fatigue. The technique also focuses on modes of person when driving the train i.e. awake, drowsy state or sleepy and sleep state. The system is very efficient to detect the fatigue and control the train also train can be controlled if it cross any such signal by which the train may collide on another train.
FIR Digital Filter Design by Sampled-Data H-infinity Discretization
Venue: arXiv cs.IT 2014
Year: 2014

FIR (finite impulse response) digital filter design is a fundamental problem in signal processing. In particular, FIR approximation of analog filters (or systems) is ubiquitous not only in signal processing but also in digital implementation of controllers. In this article, we propose a new design method of an FIR digital filter that optimally approximates a given analog filter in the sense of minimizing the H-infinity norm of the sampled-data error system. By using the lifting technique and the KYP (Kalman-Yakubovich-Popov) lemma, we reduce the H-infinity optimization to a convex optimization described by an LMI (linear matrix inequality). We also extend the method to multi-rate and multi-delay systems. A design example is shown to illustrate the effectiveness of the proposed method.
Desiging a logical security framework for e-commerce system based on soa
Venue: arXiv cs.CR 2014
Year: 2014

Rapid increases in information technology also changed the existing markets and transformed them into e- markets (e-commerce) from physical markets. Equally with the e-commerce evolution, enterprises have to recover a safer approach for implementing E-commerce and maintaining its logical security. SOA is one of the best techniques to fulfill these requirements. SOA holds the vantage of being easy to use, flexible, and recyclable. With the advantages, SOA is also endowed with ease for message tampering and unauthorized access. This causes the security technology implementation of E-commerce very difficult at other engineering sciences. This paper discusses the importance of using SOA in E-commerce and identifies the flaws in the existing security analysis of E-commerce platforms. On the foundation of identifying defects, this editorial also suggested an implementation design of the logical security framework for SOA supported E-commerce system.
Eulerian digraphs and Dyck words, a bijection
Venue: arXiv cs.DM 2014
Year: 2014

The main goal of this work is to establish a bijection between Dyck words and a family of Eulerian digraphs. We do so by providing two algorithms implementing such bijection in both directions. The connection between Dyck words and Eulerian digraphs exploits a novel combinatorial structure: a binary matrix, we call Dyck matrix, representing the cycles of an Eulerian digraph.
A Statistical Modeling Approach to Computer-Aided Quantification of Dental Biofilm
Venue: arXiv cs.CV 2014
Year: 2014

Biofilm is a formation of microbial material on tooth substrata. Several methods to quantify dental biofilm coverage have recently been reported in the literature, but at best they provide a semi-automated approach to quantification with significant input from a human grader that comes with the graders bias of what are foreground, background, biofilm, and tooth. Additionally, human assessment indices limit the resolution of the quantification scale; most commercial scales use five levels of quantification for biofilm coverage (0%, 25%, 50%, 75%, and 100%). On the other hand, current state-of-the-art techniques in automatic plaque quantification fail to make their way into practical applications owing to their inability to incorporate human input to handle misclassifications. This paper proposes a new interactive method for biofilm quantification in Quantitative light-induced fluorescence (QLF) images of canine teeth that is independent of the perceptual bias of the grader. The method partitions a QLF image into segments of uniform texture and intensity called superpixels; every superpixel is statistically modeled as a realization of a single 2D Gaussian Markov random field (GMRF) whose parameters are estimated; the superpixel is then assigned to one of three classes (background, biofilm, tooth substratum) based on the training set of data. The quantification results show a high degree of consistency and precision. At the same time, the proposed method gives pathologists full control to post-process the automatic quantification by flipping misclassified superpixels to a different state (background, tooth, biofilm) with a single click, providing greater usability than simply marking the boundaries of biofilm and tooth as done by current state-of-the-art methods.
Approximately Stable, School Optimal, and Student-Truthful Many-to-One Matchings (via Differential Privacy)
Venue: arXiv cs.GT 2014
Year: 2014

We present a mechanism for computing asymptotically stable school optimal matchings, while guaranteeing that it is an asymptotic dominant strategy for every student to report their true preferences to the mechanism. Our main tool in this endeavor is differential privacy: we give an algorithm that coordinates a stable matching using differentially private signals, which lead to our truthfulness guarantee. This is the first setting in which it is known how to achieve nontrivial truthfulness guarantees for students when computing school optimal matchings, assuming worst- case preferences (for schools and students) in large markets.
Determining surfaces of revolution from their implicit equations
Venue: arXiv cs.SC 2014
Year: 2014

Results of number of geometric operations (often used in technical practise, as e.g. the operation of blending) are in many cases surfaces described implicitly. Then it is a challenging task to recognize the type of the obtained surface, find its characteristics and for the rational surfaces compute also their parameterizations. In this contribution we will focus on surfaces of revolution. These objects, widely used in geometric modelling, are generated by rotating a generatrix around a given axis. If the generatrix is an algebraic curve then so is also the resulting surface, described uniquely by a polynomial which can be found by some well-established implicitation technique. However, starting from a polynomial it is not known how to decide if the corresponding algebraic surface is rotational or not. Motivated by this, our goal is to formulate a simple and efficient algorithm whose input is a polynomial with the coefficients from some subfield of $\mathbb{R}$ and the output is the answer whether the shape is a surface of revolution. In the affirmative case we also find the equations of its axis and generatrix. Furthermore, we investigate the problem of rationality and unirationality of surfaces of revolution and show that this question can be efficiently answered discussing the rationality of a certain associated planar curve.
Bandits Warm-up Cold Recommender Systems
Venue: arXiv cs.LG 2014
Year: 2014

We address the cold start problem in recommendation systems assuming no contextual information is available neither about users, nor items. We consider the case in which we only have access to a set of ratings of items by users. Most of the existing works consider a batch setting, and use cross-validation to tune parameters. The classical method consists in minimizing the root mean square error over a training subset of the ratings which provides a factorization of the matrix of ratings, interpreted as a latent representation of items and users. Our contribution in this paper is 5-fold. First, we explicit the issues raised by this kind of batch setting for users or items with very few ratings. Then, we propose an online setting closer to the actual use of recommender systems; this setting is inspired by the bandit framework. The proposed methodology can be used to turn any recommender system dataset (such as Netflix, MovieLens,...) into a sequential dataset. Then, we explicit a strong and insightful link between contextual bandit algorithms and matrix factorization; this leads us to a new algorithm that tackles the exploration/exploitation dilemma associated to the cold start problem in a strikingly new perspective. Finally, experimental evidence confirm that our algorithm is effective in dealing with the cold start problem on publicly available datasets. Overall, the goal of this paper is to bridge the gap between recommender systems based on matrix factorizations and those based on contextual bandits.
Graph Compartmentalization
Venue: arXiv cs.SI 2014
Year: 2014

This article introduces a concept and measure of graph compartmentalization. This new measure allows for principled comparison between graphs of arbitrary structure, unlike existing measures such as graph modularity. The proposed measure is invariant to graph size and number of groups and can be calculated analytically, facilitating measurement on very large graphs. I also introduce a block model generative process for compartmentalized graphs as a benchmark on which to validate the proposed measure. Simulation results demonstrate improved performance of the new measure over modularity in recovering the degree of compartmentalization of graphs simulated from the generative model. I also explore an application to the measurement of political polarization.
A Hybrid Parallel Implementation of the Aho-Corasick and Wu-Manber Algorithms Using NVIDIA CUDA and MPI Evaluated on a Biological Sequence Database
Venue: arXiv cs.DC 2014
Year: 2014

Multiple matching algorithms are used to locate the occurrences of patterns from a finite pattern set in a large input string. Aho-Corasick and Wu-Manber, two of the most well known algorithms for multiple matching require an increased computing power, particularly in cases where large-size datasets must be processed, as is common in computational biology applications. Over the past years, Graphics Processing Units (GPUs) have evolved to powerful parallel processors outperforming Central Processing Units (CPUs) in scientific calculations. Moreover, multiple GPUs can be used in parallel, forming hybrid computer cluster configurations to achieve an even higher processing throughput. This paper evaluates the speedup of the parallel implementation of the Aho-Corasick and Wu-Manber algorithms on a hybrid GPU cluster, when used to process a snapshot of the Expressed Sequence Tags of the human genome and for different problem parameters.
A data porting tool for coupling models with different discretization needs
Venue: arXiv cs.MS 2014
Year: 2014

The presented work is part of a larger research program dealing with developing tools for coupling biogeochemical models in contaminated landscapes. The specific objective of this article is to provide the researchers a tool to build hexagonal raster using information from a rectangular raster data (e.g. GIS format), data porting. This tool involves a computational algorithm and an open source software (written in C). The method of extending the reticulated functions defined on 2D networks is an essential key of this algorithm and can also be used for other purposes than data porting. The algorithm allows one to build the hexagonal raster with a cell size independent from the geometry of the rectangular raster. The extended function is a bi-cubic spline which can exactly reconstruct polynomials up to degree three in each variable. We validate the method by analyzing errors in some theoretical case studies followed by other studies with real terrain elevation data. We also introduce and briefly present an iterative water routing method and use it for validation on a case with concrete terrain data.
UCov: a User-Defined Coverage Criterion for Test Case Intent Verification
Venue: arXiv cs.SE 2014
Year: 2014

The goal of regression testing is to ensure that the behavior of existing code is not altered by new program changes. The primary focus of regression testing should be on code associated with: a) earlier bug fixes; and b) particular application scenarios considered to be important by the tester. Existing coverage criteria do not enable such focus, e.g., 100% branch coverage does not guarantee that a given bug fix is exercised or a given application scenario is tested. Therefore, there is a need for a complementary coverage criterion in which the user can define a test requirement characterizing a given behavior to be covered as opposed to choosing from a pool of pre-defined and generic program elements. We propose UCov, a user-defined coverage criterion wherein a test requirement is an execution pattern of program elements and predicates. Our proposed criterion is not meant to replace existing criteria, but to complement them as it focuses the testing on important code patterns that could go untested otherwise. UCov supports test case intent verification. For example, following a bug fix, the testing team may augment the regression suite with the test case that revealed the bug. However, this test case might become obsolete due to code modifications not related to the bug. But if an execution pattern characterizing the bug was defined by the user, UCov would determine that test case intent verification failed. We implemented our methodology for the Java platform and applied it onto two real life case studies. Our implementation comprises the following: 1) an Eclipse plugin allowing the user to easily specify non-trivial test requirements; 2) the ability of cross referencing test requirements across subsequent versions of a given program; and 3) the ability of checking whether user-defined test requirements were satisfied, i.e., test case intent verification.
CIDI-Lung-Seg: A Single-Click Annotation Tool for Automatic Delineation of Lungs from CT Scans
Venue: arXiv cs.CV 2014
Year: 2014

Accurate and fast extraction of lung volumes from computed tomography (CT) scans remains in a great demand in the clinical environment because the available methods fail to provide a generic solution due to wide anatomical variations of lungs and existence of pathologies. Manual annotation, current gold standard, is time consuming and often subject to human bias. On the other hand, current state-of-the-art fully automated lung segmentation methods fail to make their way into the clinical practice due to their inability to efficiently incorporate human input for handling misclassifications and praxis. This paper presents a lung annotation tool for CT images that is interactive, efficient, and robust. The proposed annotation tool produces an "as accurate as possible" initial annotation based on the fuzzy-connectedness image segmentation, followed by efficient manual fixation of the initial extraction if deemed necessary by the practitioner. To provide maximum flexibility to the users, our annotation tool is supported in three major operating systems (Windows, Linux, and the Mac OS X). The quantitative results comparing our free software with commercially available lung segmentation tools show higher degree of consistency and precision of our software with a considerable potential to enhance the performance of routine clinical tasks.
Effects of Mobility on User Energy Consumption and Total Throughput in a Massive MIMO System
Venue: arXiv cs.IT 2014
Year: 2014

Macroscopic mobility of wireless users is important to determine the performance and energy effciency of a wireless network, because of the temporal correlations it introduces in the consumed power and throughput. In this work we introduce a methodology that obtains the long time statistics of such metrics in a network. After describing the general approach, we present a specific example of the uplink channel of a mobile user in the vicinity of a massive MIMO base-station antenna array. To guarantee a fixed SINR and rate, the user inverts the path-loss channel power, while moving around in the cell. To calculate the long time distribution of the consumed energy of the user, we assume his movement follows a Brownian motion, and then map the problem to the solution of the minimum eigenvalue of a partial differential equation, which can be solved either analytically, or numerically very fast. We also treat the throughput of a single user. We then discuss the results and how they can be generalized if the mobility is assumed to be a Levy random walk. We also provide a roadmap to use this technique when one considers multiple users and base stations.
Value of Targeting
Venue: arXiv cs.GT 2014
Year: 2014

We undertake a formal study of the value of targeting data to an advertiser. As expected, this value is increasing in the utility difference between realizations of the targeting data and the accuracy of the data, and depends on the distribution of competing bids. However, this value may vary non-monotonically with an advertiser's budget. Similarly, modeling the values as either private or correlated, or allowing other advertisers to also make use of the data, leads to unpredictable changes in the value of data. We address questions related to multiple data sources, show that utility of additional data may be non-monotonic, and provide tradeoffs between the quality and the price of data sources. In a game-theoretic setting, we show that advertisers may be worse off than if the data had not been available at all. We also ask whether a publisher can infer the value an advertiser would place on targeting data from the advertiser's bidding behavior and illustrate that this is impossible.