2,429 research outputs found
Maximum Resilience of Artificial Neural Networks
The deployment of Artificial Neural Networks (ANNs) in safety-critical
applications poses a number of new verification and certification challenges.
In particular, for ANN-enabled self-driving vehicles it is important to
establish properties about the resilience of ANNs to noisy or even maliciously
manipulated sensory input. We are addressing these challenges by defining
resilience properties of ANN-based classifiers as the maximal amount of input
or sensor perturbation which is still tolerated. This problem of computing
maximal perturbation bounds for ANNs is then reduced to solving mixed integer
optimization problems (MIP). A number of MIP encoding heuristics are developed
for drastically reducing MIP-solver runtimes, and using parallelization of
MIP-solvers results in an almost linear speed-up in the number (up to a certain
limit) of computing cores in our experiments. We demonstrate the effectiveness
and scalability of our approach by means of computing maximal resilience bounds
for a number of ANN benchmark sets ranging from typical image recognition
scenarios to the autonomous maneuvering of robots.Comment: Timestamp research work conducted in the project. version 2: fix some
typos, rephrase the definition, and add some more existing wor
Les déterminants des performances scolaires des élèves marocains
Le Maroc fait partie des pays en développement dont le niveau des acquis des élèves reste relativement faible. En dépit des efforts engagés en vue d’améliorer en partie la qualité des apprentissages, les résultats des enquêtes internationales et nationales révèlent de faibles niveaux des acquis. Dès lors, l’objectif de cet article est de revenir sur les facteurs qui influencent les performances scolaires des élèves. Nous nous intéressons plus spécifiquement aux déterminants microéconomiques de la qualité de l’éducation à travers les performances des élèves. Les études sur les déterminants des performances scolaires sont riches d’enseignement. Les premières contributions se sont focalisées sur le rôle de l’environnement familial dans l’explication de la réussite des élèves (Coleman, 1966, par exemple). D’autres, plus récemment, ont abordé les facteurs liés à l’établissement scolaire. Pour autant, les contributions récentes mettent en avant l’importance à la fois de l’environnement familial et de l’école (Hanushek, 2003). Des travaux plus récents oulignent également l’influence des pairs sur les performances scolaires. Le présent travail s’inscrit dans cette logique. Son originalité se situe à un double niveau. La première réside dans la mise en évidence de l’ensemble des facteurs explicatifs des performances des élèves et des inégalités scolaires. Malgré l’existence d’une littérature abondante sur le sujet, cette question n’a pas été abordée, à notre connaissance, dans le cas marocain. La seconde cherche à corriger les problèmes d’endogénéité dans les modèles multiniveaux. Enfin, La technique d’imputation adoptée permet de traiter de façon pertinente les valeurs manquantes dans les bases de données. Cet article est structuré en trois parties. La première aborde la littérature empirique sur les déterminants de la réussite scolaire des élèves. La deuxième partie examine le modèle utilisé et décrit la base de données du Programme national d’évaluation des acquis (PNEA). Elle examine l’approche et la méthodologie utilisée. Enfin, la troisième partie traite des résultats obtenus et nous permet de formuler les principaux enseignements pouvant être tirés de nos résultats en matière de politiques publiques
Basic data report on the turbulent spread of heat & matter
CER71-72RSM-9.August 1971.Includes bibliographical references (page 75).United States Dept. of Interior Geological Survey, Water Resources Division in cooperation with the United States Environmental Protection Agency, National Thermal Pollution Research Program.The purpose of this report is to present the results of an investigation of the turbulent transport properties of heated and salt water jets in an open channel flow. The data were taken cooperatively by the U.S. Geological Survey and the Environmental Protection Agency. The data include measurement of the turbulence characteristics, longitudinal dispersion, and vertical and lateral turbulent diffusion. Three different boundary roughnesses were used in the investigation. The turbulence data includes the intensity of turbulence, Eulerian time scales, autocorrelation function distributions, space correlation distributions in the vertical and horizontal directions and space-time correlation function distributions in the longitudinal direction. Vertical and lateral turbulent diffusion data were obtained downstream from jets of three diameters, at four different jet strengths. Two tracer fluids, heated water and a neutrally buoyant salt solution were used. Only basic data are reported here. The extensive analysis of these results will be the subject of a future publication
Cuckoo search algorithm based for tunning both PI and FOPID controllers for the DFIG-Wind energy conversion system
Wind Energy has received great attention in this century. It influences the new power systems, adding new challenges to the power system expansion problem. Nowadays, double feed induction generator (DFIG) wind turbines are used majorly in wind farms, due to their advantages over other types. Therefore, the analysis of the system using this type has become very important. In this paper, a wind turbine modelling was introduced with suggested controllers, in order to enhance the system response, with respect to both pitch control and maximum output power. Cuckoo search algorithm (CSA), a meta-heuristic optimization technique, was implemented to determine the gains of a proportional-integral (PI) controller and fractional order proportional-integral-derivative (FOPID) controller to optimize the system, which considered three control loops: pitch, rotor-side converter, and grid-side converter control loop. Simulation results were determined using MATLAB/Simulink. The comparative analysis of the results showed that the PI Controller gave the simplest and the best response in case of the pitch and rotor-side control loops while the FOPID was the best when applied to the grid-side control loop. Based on the results and discussion,
a suggestion of using a compination of each controller was introduced
Comparative Transcriptomics and Genomics from Continuous Axenic Media Growth Identifies
Coxiella burnetii (Cb) is an obligate intracellular pathogen in nature and the causative agent of acute Q fever as well as chronic diseases. In an effort to identify genes and proteins crucial to their normal intracellular growth lifestyle, we applied a Reverse evolution approach where the avirulent Nine Mile Phase II strain of Cb was grown for 67 passages in chemically defined ACCM-D media and gene expression patterns and genome integrity from various passages was compared to passage number one following intracellular growth. Transcriptomic analysis identified a marked downregulation of the structural components of the type 4B secretion system (T4BSS), the general secretory (sec) pathway, as well as 14 out of 118 previously identified genes encoding effector proteins. Additional downregulated pathogenicity determinants genes included several chaperones, LPS, and peptidoglycan biosynthesis. A general marked downregulation of central metabolic pathways was also observed, which was balanced by a marked upregulation of genes encoding transporters. This pattern reflected the richness of the media and diminishing anabolic and ATP-generation needs. Finally, genomic sequencing and comparative genomic analysis demonstrated an extremely low level of mutation across passages, despite the observed Cb gene expression changes following acclimation to axenic media
A Dedicated Tool Frame Based Tongue Interface Layout Improves 2D Visual Guided Control of an Assistive Robotic Manipulator – a Design Parameter for Tele-applications
A high-resolution tongue based joystick to enable robot control for individuals with severe disabilities
BOTANICAL AND GENETIC CHARACTERIZATION OF CITRUS MAXIMA (BURM.) MERRILL. F. RUTACEAE
Objective: Total investigation of the macro-and micromorphological features of Citrus maxima (Burm.) Merrill. In addition, DNA fingerprinting in this study was to estimate genetic polymorphism and relationships with another citrus viz: Citrus paradise and Citrus sinensis based on RAPD and ISSR markers.Methods: For the establishment of macro-and micromorphological investigation and genetic estimation, this study presents a total investigation of the macro-and micromorphological features of the roots, stems, leaves, flowers, fruits and seeds of the plants through microscopical investigation of the prepared entire, transverse sections and powdered forms of different organs under study. Furthermore, the DNA of the three plants was extracted from leaf samples and two types of DNA markers RAPD and ISSR were assayed.Results: Macro-and micromorphological features of different organs were investigated. On the other hand Genetic polymorphism and relationships among Citrus maxima, Citrus paradisi and Citrus sinensis was revealed. The highest genetic similarity was between Citrus maxima and Citrus paradisi while the lowest similarity was between Citrus paradisi and Citrus sinensis as revealed by RAPD, ISSR and combined data.Conclusion: For the present study, macro and micro-morphological characters, as well as, DNA fingerprinting can be considered as the identifying parameters for authentication of Citrus maxima (Burm.) Merrill
Design and evaluation of a noninvasive tongue-computer interface for individuals with severe disabilities
Tongue-computer interfaces have shown the potential to control assistive devices developed for individuals with severe disabilities. However, current efficient tongue-computer interfaces require invasive methods for attaching the sensor activation units to the tongue, such as piercing. In this study, we propose a noninvasive tongue-computer interface to avoid the requirement of invasive activation unit attachment methods. We developed the noninvasive tongue-computer interface by integrating an activation unit on a frame, and mounting the frame on an inductive tongue-computer interface (ITCI). Thus, the users are able to activate the inductive sensors on the interface by positioning the activation unit with their tongue. They also do not need to remount the activation unit before each use. We performed pointing tests for controlling a computer cursor and number typing tests with two able-bodied participants, where one of them was experienced with using invasive tongue-computer interfaces and other one had no experience. We measured throughput and movement error for pointing tasks, and speed and accuracy for number typing tasks for the evaluation of the feasibility and performance of the developed noninvasive system. Results show that the inexperienced participant achieved similar results with the developed noninvasive tongue-computer interface compared to the current invasive version of the ITCI, while the experienced participant performed better with the invasive tongue-computer interface
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