Página 36 dos resultados de 2566 itens digitais encontrados em 0.038 segundos

Design of a solar competition vehicle strategy with a Cyber Physical System approach

Mej??a Guti??rrez, Ricardo; Osorio G??mez, Gilberto; Serrano Rico, Andr??s; Gaviria Mej??a, Pablo; Barrera Vel??squez, Jorge
Fonte: Grupo de Investigaci??n en Ingenier??a de Dise??o - GRID; Design Engineering Research Group - GRID; Escuela de Ingenier??a Publicador: Grupo de Investigaci??n en Ingenier??a de Dise??o - GRID; Design Engineering Research Group - GRID; Escuela de Ingenier??a
Tipo: conferenceObject; Documento de conferencia; publishedVersion
Português
Relevância na Pesquisa
349.92035%
Solar Energy has been a challenge in mobility solutions -- That is why some world-class contests have been pushing researchers and practitioners to find optimal solutions for an efficient integration of solar powered vehicles -- This article presents the design and implementation of the strategy and performance monitoring for the first Colombian solar competition vehicle with a Cyber-Physical System (CPS) approach -- The strategy system, as well as CPSs, has to deal with two kinds of elements: physical technologies and cyber technologies -- They interact with the environment, the human domain and each other -- The understanding and implementation of these interactions will be described, being the key for designing an effective strategy system in order to improve the vehicle???s performance

Power system energy analysis incorporating comprehensive load characteristics

Jin, Ma; Hill, David; Dong, Zhao Yang; He, Renmu
Fonte: Institute of Engineering and Technology Publicador: Institute of Engineering and Technology
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
349.92035%
The energy function method developed so far assumes that the active load is constant. However, most of the actual load is voltage dependent, which hinders the application of the energy analysis method to the actual power system. On the other hand, the fas

Assessing Excel VBA Suitability for Monte Carlo Simulation

Botchkarev, Alexei
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/03/2015 Português
Relevância na Pesquisa
349.92035%
Monte Carlo (MC) simulation includes a wide range of stochastic techniques used to quantitatively evaluate the behavior of complex systems or processes. Microsoft Excel spreadsheets with Visual Basic for Applications (VBA) software is, arguably, the most commonly employed general purpose tool for MC simulation. Despite the popularity of the Excel in many industries and educational institutions, it has been repeatedly criticized for its flaws and often described as questionable, if not completely unsuitable, for statistical problems. The purpose of this study is to assess suitability of the Excel (specifically its 2010 and 2013 versions) with VBA programming as a tool for MC simulation. The results of the study indicate that Microsoft Excel (versions 2010 and 2013) is a strong Monte Carlo simulation application offering a solid framework of core simulation components including spreadsheets for data input and output, VBA development environment and summary statistics functions. This framework should be complemented with an external high-quality pseudo-random number generator added as a VBA module. A large and diverse category of Excel incidental simulation components that includes statistical distributions, linear and non-linear regression and other statistical...

Reverse Engineering Socialbot Infiltration Strategies in Twitter

Freitas, Carlos A.; Benevenuto, Fabrício; Ghosh, Saptarshi; Veloso, Adriano
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/05/2014 Português
Relevância na Pesquisa
349.92035%
Data extracted from social networks like Twitter are increasingly being used to build applications and services that mine and summarize public reactions to events, such as traffic monitoring platforms, identification of epidemic outbreaks, and public perception about people and brands. However, such services are vulnerable to attacks from socialbots $-$ automated accounts that mimic real users $-$ seeking to tamper statistics by posting messages generated automatically and interacting with legitimate users. Potentially, if created in large scale, socialbots could be used to bias or even invalidate many existing services, by infiltrating the social networks and acquiring trust of other users with time. This study aims at understanding infiltration strategies of socialbots in the Twitter microblogging platform. To this end, we create 120 socialbot accounts with different characteristics and strategies (e.g., gender specified in the profile, how active they are, the method used to generate their tweets, and the group of users they interact with), and investigate the extent to which these bots are able to infiltrate the Twitter social network. Our results show that even socialbots employing simple automated mechanisms are able to successfully infiltrate the network. Additionally...

Community Detection in Complex Networks using Genetic Algorithm

Tasgin, Mursel; Bingol, Haluk
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 18/04/2006 Português
Relevância na Pesquisa
349.92035%
Community structure identification has been an important research topic in complex networks and there has been many algorithms proposed so far to detect community structures in complex networks, where most of the algorithms are not suitable for very large networks because of their time-complexity. Genetic algorithm for detecting communities in complex networks, which is based on optimizing network modularity using genetic algorithm, is presented here. It is scalable to very large networks and does not need any priori knowledge about number of communities or any threshold value. It has O(e) time-complexity where e is the number of edges in the network. Its accuracy is tested with the known Zachary Karate Club and College Football datasets. Enron e-mail dataset is used for scalability test.; Comment: submitted to Physical Review,waiting for response; 6 pages. See also: Tasgin, M.,"Community Detection Model using Genetic Algorithm in Complex Networks and Its Application in Real-Life Networks", MS Thesis, Graduate Program in Computer Engineering, Bogazici University, 2005

Morphological Analysis as Classification: an Inductive-Learning Approach

Bosch, Antal van den; Daelemans, Walter; Weijters, Ton
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 16/07/1996 Português
Relevância na Pesquisa
349.92035%
Morphological analysis is an important subtask in text-to-speech conversion, hyphenation, and other language engineering tasks. The traditional approach to performing morphological analysis is to combine a morpheme lexicon, sets of (linguistic) rules, and heuristics to find a most probable analysis. In contrast we present an inductive learning approach in which morphological analysis is reformulated as a segmentation task. We report on a number of experiments in which five inductive learning algorithms are applied to three variations of the task of morphological analysis. Results show (i) that the generalisation performance of the algorithms is good, and (ii) that the lazy learning algorithm IB1-IG performs best on all three tasks. We conclude that lazy learning of morphological analysis as a classification task is indeed a viable approach; moreover, it has the strong advantages over the traditional approach of avoiding the knowledge-acquisition bottleneck, being fast and deterministic in learning and processing, and being language-independent.; Comment: 11 pages, 5 encapsulated postscript figures, uses non-standard NeMLaP proceedings style nemlap.sty; inputs ipamacs (international phonetic alphabet) and epsf macros

FixRoute: A Unified Logic and Numerical Tool for Provably Safe Internet Traffic Engineering

Arzani, Behnaz; Gurney, Alexander; Li, Bo; Han, Xianglong; Guerin, Roch; Loo, Boon Thau
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 27/11/2015 Português
Relevância na Pesquisa
349.92035%
The performance of networks that use the Internet Protocol is sensitive to precise configuration of many low-level parameters on each network device. These settings govern the action of dynamic routing protocols, which direct the flow of traffic; in order to ensure that these dynamic protocols all converge to produce some 'optimal' flow, each parameter must be set correctly. Multiple conflicting optimization objectives, nondeterminism, and the need to reason about different failure scenarios make the task particularly complicated. We present a fast and flexible approach for the analysis of a number of such management tasks presented in the context of BGP routing. The idea is to combine {\em logical} satisfiability criteria with traditional {\em numerical} optimization, to reach a desired traffic flow outcome subject to given constraints on the routing process. The method can then be used to probe parameter sensitivity, trade-offs in the selection of optimization goals, resilience to failure, and so forth. The theory is underpinned by a rigorous abstraction of the convergence of distributed asynchronous message-passing protocols, and is therefore generalizable to other scenarios. Our resulting hybrid engine is faster than either purely logical or purely numeric alternatives...

Reverse Engineering Chemical Reaction Networks from Time Series Data

Searson, Dominic P.; Willis, Mark J.; Wright, Allen
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/12/2014 Português
Relevância na Pesquisa
349.92035%
The automated inference of physically interpretable (bio)chemical reaction network models from measured experimental data is a challenging problem whose solution has significant commercial and academic ramifications. It is demonstrated, using simulations, how sets of elementary reactions comprising chemical reaction networks, as well as their rate coefficients, may be accurately recovered from non-equilibrium time series concentration data, such as that obtained from laboratory scale reactors. A variant of an evolutionary algorithm called differential evolution in conjunction with least squares techniques is used to search the space of reaction networks in order to infer both the reaction network topology and its rate parameters. Properties of the stoichiometric matrices of trial networks are used to bias the search towards physically realisable solutions. No other information, such as chemical characterisation of the reactive species is required, although where available it may be used to improve the search process.; Comment: 36 pages. In: Dehmer, M., Varmuza, K., Bonchev, D, ed. Statistical Modelling of Molecular Descriptors in QSAR/QSPR. Weinheim, Germany: Wiley-VCH Verlag GmbH, 2012, pp.327-348

Engineering Small Space Dictionary Matching

Sokol, Shoshana Marcus Dina
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 27/01/2013 Português
Relevância na Pesquisa
349.92035%
The dictionary matching problem is to locate occurrences of any pattern among a set of patterns in a given text. Massive data sets abound and at the same time, there are many settings in which working space is extremely limited. We introduce dictionary matching software for the space-constrained environment whose running time is close to linear. We use the compressed suffix tree as the underlying data structure of our algorithm, thus, the working space of our algorithm is proportional to the optimal compression of the dictionary. We also contribute a succinct tool for performing constant-time lowest marked ancestor queries on a tree that is succinctly encoded as a sequence of balanced parentheses, with linear time preprocessing of the tree. This tool should be useful in many other applications. Our source code is available at http://www.sci.brooklyn.cuny.edu/~sokol/dictmatch.html

Traffic Engineering Based on Effective Envelope Algorithm on Novel Resource Reservation Method over Mobile Internet Protocol Version 6

Malekian, Reza; Abdullah, Abdul Hanan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/11/2012 Português
Relevância na Pesquisa
349.92035%
The first decade of the 21st century has seen tremendous improvements in mobile internet and its technologies. The high traffic volume of services such as video conference and other real-time traffic applications are imposing a great challenge on networks. In the meantime, demand for the use of mobile devices in computation and communication such as smart phones, personal digital assistants, and mobile-enabled laptops has grown rapidly. These services have driven the demand for increasing and guaranteing bandwidth requirements in the network. A direction of this paper is in the case of resource reservation protocol (RSVP) over mobile IPv6 networks. There are numbers of proposed solutions for RSVP and quality of service provision over mobile IPv6 networks, but most of them using advanced resource reservation. In this paper, we propose a mathematical model to determine maximum end-to-end delay bound through intermediate routers along the network. These bounds are sent back to the home agent for further processing. Once the home agent receives maximum end-to-end delay bounds, it calculates cumulative bound and compares this bound with the desired application end-to-end delay bound to make final decision on resource reservation. This approach improves network resource utilization.; Comment: International Journal of Innovative Computing...

A reverse engineering approach to the suppression of citation biases reveals universal properties of citation distributions

Radicchi, Filippo; Castellano, Claudio
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/03/2012 Português
Relevância na Pesquisa
349.92035%
The large amount of information contained in bibliographic databases has recently boosted the use of citations, and other indicators based on citation numbers, as tools for the quantitative assessment of scientific research. Citations counts are often interpreted as proxies for the scientific influence of papers, journals, scholars, and institutions. However, a rigorous and scientifically grounded methodology for a correct use of citation counts is still missing. In particular, cross-disciplinary comparisons in terms of raw citation counts systematically favors scientific disciplines with higher citation and publication rates. Here we perform an exhaustive study of the citation patterns of millions of papers, and derive a simple transformation of citation counts able to suppress the disproportionate citation counts among scientific domains. We find that the transformation is well described by a power-law function, and that the parameter values of the transformation are typical features of each scientific discipline. Universal properties of citation patterns descend therefore from the fact that citation distributions for papers in a specific field are all part of the same family of univariate distributions.; Comment: 9 pages, 6 figures. Supporting information files available at http://filrad.homelinux.org

Strong motion earthquake accelerograms, digitized and plotted data, Volume I - uncorrected accelerograms; Part D - accelerograms ID056 through ID070

Earthquake Engineering Research Laboratory,
Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Report or Paper; PeerReviewed Formato: application/pdf
Publicado em 01/01/1971 Português
Relevância na Pesquisa
279.26729%
The first set of twenty uncorrected digitized earthquake accelerograms was published in July, 1969, as Volume I, Part A, of the present series. That volume also contained introductory material and background information describing the methods used, accuracies, etc., which should be referred to by all users of the data. The San Fernando Earthquake provided records of sufficient importance that the original plan was interrupted after two parts, and Part C contained the first of the San Fernando Earthquake accelerograms. This issue continues the San Fernando accelerograms and contains fifteen records consisting of three records each from four buildings, two ground level records at the Hollywood Storage Building and the record from the Old Ridge Route at Castaic. Some comments on these records follow. ID056. Castaic, Old Ridge Route. At 0.97 seconds after triggering the drive mechanism malfunctioned briefly and the film was stationary for a short length of time with the recording light on. The actual time is indicated by asterisks in the computer printout and by arrows in the computer plot. The lost portion of trace can be estimated to be one to two seconds long for the following reasons. The gap between the time marks is normally 0.5 seconds...

Knowledge-Driven Board-Level Functional Fault Diagnosis

Ye, Fangming
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2014 Português
Relevância na Pesquisa
349.92035%

The semiconductor industry continues to relentlessly advance silicon technology scaling into the deep-submicron (DSM) era. High integration levels and structured design methods enable complex systems that can be manufactured in high volume. However, due to increasing integration densities and high operating speeds, subtle manifestation of defects leads to functional failures at the board level. Functional fault diagnosis is, therefore, necessary for board-level product qualification. However, ambiguous diagnosis results can lead to long debug times and wrong repair actions, which significantly increase repair cost and adversely impact yield.

A state-of-the-art diagnosis system involves several key components: (1) design of functional test programs, (2) collection of functional-failure syndromes, (3) building of the diagnosis engine, (4) isolation of root causes, and (5) evaluation of the diagnosis engine. Advances in each of these components can pave the way for a more effective diagnosis system, thus improving diagnosis accuracy and reducing diagnosis time. Machine-learning techniques offer an unprecedented opportunity to develop an automated and adaptive diagnosis system to increase diagnosis accuracy and speed. This dissertation targets all the above components of an advanced diagnosis system by leveraging various machine-learning techniques.

This thesis first describes a diagnosis system based on support-vector machines (SVMs)...

An Evaluation of the S2Ia switched-current architecture for (delta)(sigma) modulator ADCs

Botha, Andre
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
349.92035%
Switched-Current (SI) is a design methodology by which discrete time, current mode, analog circuits can be implemented using standard digital CMOS processes, allowing the addition of analog signal processing circuits, analog to digital converters (ADCs), digital to analog converters (DACs) and other analog and mixed-signal circuits to otherwise digital only microchips without the need and expense of any extra fabrication steps. SI circuits operate by employing a secondary effect in CMOS circuits, a transistor's gate capacitance, to store charge and thus form a current memory cell. A current memory cell is one of the basic building blocks found in most SI circuits and is usually the distinguishing feature of the various approaches to SI circuit design. Delta Sigma Modulators (DSMs) are discrete time, mixed-signal circuits making them well suited to implementation using the SI methodology. These circuits can form the basis of either an ADC or DAC and thus provide a good example of the SI technique employing a particular current memory cell implementation. For this work, a First Order DSM-based ADC was designed and simulated to verify the feasibility of a variant of the S2I Switched-Current Memory Cell architecture, the S2Ia Switched-Current Memory Cell...

Reliability analysis of triple modular redundancy system with spare

Al-Kofahi, Khalid A.
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
349.92035%
Hardware redundant fault-tolerant systems and the different design approaches are discussed. The reliability analysis of fault-tolerant systems is usually done under permanent fault conditions. With statistical data suggesting that up to 90% of system failures are caused by intermittent faults, the reliability analysis of fault-tolerant systems must concentrate more on this class of faults. In this work, a reconfigurable Triple Modular Redundancy (TMR) with spare system that differentiates between permanent and intermittent faults has been built. The reconfiguration process of this system depends on both the current status of its modules and their history. Based on this, a different approach for reliability analysis under intermittent fault conditions using Markov models is presented. This approach shows a much higher system reliability compared to other redundant and non-redundant configurations.

Improved methods and system for watermarking halftone images

Sherry, Phil
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
349.92035%
Watermarking is becoming increasingly important for content control and authentication. Watermarking seamlessly embeds data in media that provide additional information about that media. Unfortunately, watermarking schemes that have been developed for continuous tone images cannot be directly applied to halftone images. Many of the existing watermarking methods require characteristics that are implicit in continuous tone images, but are absent from halftone images. With this in mind, it seems reasonable to develop watermarking techniques specific to halftones that are equipped to work in the binary image domain. In this thesis, existing techniques for halftone watermarking are reviewed and improvements are developed to increase performance and overcome their limitations. Post-halftone watermarking methods work on existing halftones. Data Hiding Cell Parity (DHCP) embeds data in the parity domain instead of individual pixels. Data Hiding Mask Toggling (DHMT) works by encoding two bits in the 2x2 neighborhood of a pseudorandom location. Dispersed Pseudorandom Generator (DPRG), on the other hand, is a preprocessing step that takes place before image halftoning. DPRG disperses the watermark embedding locations to achieve better visual results. Using the Modified Peak Signal-to-Noise Ratio (MPSNR) metric...

The Design, modeling and simulation of switching fabrics: For an ATM network switch

Molokov, Dmitriy
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
349.92035%
The requirements of today's telecommunication systems to support high bandwidth and added flexibility brought about the expansion of (Asynchronous Transfer Mode) ATM as a new method of high-speed data transmission. Various analytical and simulation methods may be used to estimate the performance of ATM switches. Analytical methods considerably limit the range of parameters to be evaluated due to extensive formulae used and time consuming iterations. They are not as effective for large networks because of excessive computations that do not scale linearly with network size. One the other hand, simulation-based methods allow determining a bigger range of performance parameters in a shorter amount of time even for large networks. A simulation model, however, is more elaborate in terms of implementation. Instead of using formulae to obtain results, it has to operate software or hardware modules requiring a certain amount of effort to create. In this work simulation is accomplished by utilizing the ATM library - an object oriented software tool, which uses "software chips" for building ATM switches. The distinguishing feature of this approach is cut-through routing realized on the bit level abstraction treating ATM protocol data units, called cells...

0.18 µm CMOS low power standard cell library

Gunawan, Suryadi
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
349.92035%
With the increasing number of transistors in a single integrated circuit, power is becoming one of the major issues in integrated circuit development. This issue requires additional effort from designers in order to produce lower power designs. The purpose of this thesis is to develop a standard cell library using Taiwan Semiconductor Manufacturing Company's 0.18-micron CMOS technology. The library cells consume less power compared to the vendor library provided by MOSIS. Although a reduction in power consumption is the main objective in this cell library, the timing delay and area are two aspects that cannot be ignored. However, a sacrifice has to be made in timing delay or area in order to achieve the goal of lower power. In order to produce a library that contains low power cells, a new design technique must be used while keeping in mind that power reduction should not adversely affect other aspects of the cell. Drawbacks in previously published design techniques will be analyzed and a new design technique composed of parts of previous techniques will then be postulated. The new technique will then be compared against the best technique currently available. A design technique for standard cell library development can be determined based on the results of that comparison. The new design technique can then be implemented into a cell library. The cell library is developed and characterized using Mentor Graphic tools. The newly produced cell library will then be compared to a similar technique used by the vendor library...

The Design and modeling of input and output modules for an ATM network switch

Murphy, Darin
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
349.92035%
The purpose of this thesis is to design, model, and simulate both an input and an output module for an ATM network switch. These devices are used to interface an ATM switch with the physical protocol that is transporting data along the actual transmission medium. The I/O modules have been designed specifically to interface with the Synchronous Optical Network (SONET) protocol. This thesis studies the ATM protocol and examines the issues involved with designing an ATM I/O module chipset. A model of the design was then implemented in both C++ and \TTDL. These models were simulated in order to verify functionality and document performance. The intent of this work is to provide the background and models necessary to aid in the further study and development of entire ATM switch architectures. The input and output modules .ire onlv two functional pieces of a complete ATM switch. The software models that have been implemented by this thesis can be integrated with the other necessary functional blocks to form a complete model of a working ATM switch. These functional blocks can then be rearranged and altered to assist in the study of how different switch architectures can effect overall network performance and efficiency. The input and output modules have been designed to be as flexible as possible in order to easily adapt to future modifications.

Heuristics for selecting gray scale morphological structuring elements

Fetter, Paul
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
349.92035%
This thesis explores some heuristics for choosing 8 bit gray scale morphological structuring elements for reducing noise. The variables of size, shape and volume that enter into the choice of structuring elements create a very large number of possible structuring elements. Some general heuristics to guide the choice of an appropriate structuring element will make the task easier. Both the absolute error of the image and the appearance of the image will be used to judge the results. The experiments were performed on 3 images. Each of the images had noise added before processing; one set of data had 10 percent of the pixels disturbed by noise, the other had 20 percent of the pixels disturbed by noise. The resulting 6 images were then filtered with 10 different structuring elements and the resulting images were then compared against the respective baseline image. The conclusions were guided by the resulting absolute error values.