The Experts below are selected from a list of 431961 Experts worldwide ranked by ideXlab platform

Kasper Peeters - One of the best experts on this subject based on the ideXlab platform.

  • cadabra a field theory motivated symbolic Computer algebra system
    Computer Physics Communications, 2007
    Co-Authors: Kasper Peeters
    Abstract:

    Field theory is an area in physics with a deceptively compact notation. Although general purpose Computer algebra systems, built around generic list-based data structures, can be used to represent and manipulate field-theory expressions, this often leads to cumbersome input formats, unexpected side-effects, or the need for a lot of special-purpose code. This makes a direct translation of problems from paper to Computer and back needlessly time-consuming and error-prone. A prototype Computer algebra system is presented which features TEX-like input, graph data structures, lists with Young-tableaux symmetries and a multiple-inheritance property system. The usefulness of this approach is illustrated with a number of explicit field-theory problems. 1. Field theory versus General-Purpose Computer algebra

D. Allan - One of the best experts on this subject based on the ideXlab platform.

  • ICASSP - An LPC k-parameter software speech synthesizer via dynamic microprogramming a general purpose Computer
    ICASSP '79. IEEE International Conference on Acoustics Speech and Signal Processing, 1
    Co-Authors: L. Morris, D. Allan
    Abstract:

    In a previous paper, it was shown that the presence of a combinatorial shifter in the data paths of a user microprogrammable general purpose Computer could be used for fast fixed-point multiplication if a unique microsubroutine was created for each required multiplier. A sixth-order direct form IIR digital filter was implemented via this technique. This work has been extended, so as to produce a tenth-order LPC k-parameter lattice synthesizer software system which executes in about 60% real time. The remaining CPU time may be allocated for k-parameter manipulation, as in synthesis-by-rule aAgorithms, or for unrelated computation. The approach used is novel since it involves dynamic analysis of k-parameters and creation of the microsubroutines required for synthesis during each pitch period. The results suggest that a high speed shifter embedded in an otherwise conventional micromachine architecture is Useful for practical, real-time digital signal processing applications.

Roger T. Fenner - One of the best experts on this subject based on the ideXlab platform.

  • General-Purpose Computer program for shape optimization of engineering structures using the boundary element method
    Computers & Structures, 1995
    Co-Authors: Azam Tafreshi, Roger T. Fenner
    Abstract:

    Abstract Optimization of the shape of structural components is often concerned with minimizing stress concentration effects to ensure a longer fatigue life. A general purpose Computer program, STRESOPT, for shape optimal design of two-dimensional structures in order to smooth stress peaks is presented. The program has three main parts: the stress analyzer, design sensitivity analyzer and optimizer. The stress analyzer and design sensitivity analyzer use the boundary element method with isoparametric quadratic boundary elements. The boundary element method is very suitable for shape optimization and in comparison with the finite element method needs much less data, related only to the boundary of the structure being considered. Because a differentiated form of the boundary integral equation (on which the boundary element method is based) can be used directly to determine the derivatives of the objective and constraint functions, the accuracy of computation is very high. The numerical optimization method used in the program is the extended penalty function approach, using the BFGS variable metric for unconstrained minimization, together with the Golden Section method for the one-dimensional search. Initial mesh preparation and regeneration of the boundary elements during the iterative process of optimization is both straightforward and fast. Hermitian cubic splines are well suited for the boundary shape representation, and complex geometries can be described in a very compact way by a small number of design variables. Applications of the program to the optimum shape design of fillets and holes in plates and bars are presented.

Natassya B. F. Silva - One of the best experts on this subject based on the ideXlab platform.

  • ISCC - Comparison of secure communication with AES between embedded system and general purpose Computer
    2020 IEEE Symposium on Computers and Communications (ISCC), 2020
    Co-Authors: Augusto C. Ferreira, Natassya B. F. Silva
    Abstract:

    Embedded systems are the combination between hardware and software designed to perform some specifics functions. An embedded system is generally a part of a larger system that uses a Computer network to communicate with other devices. For this reason, secure communication is of great importance to guarantee the confidentiality of the transmitted information, which can be provided by using encryption algorithms. The security is usually not a requirement when designing an embedded system, causing few techniques to be implemented for the security of these devices. This paper presents an evaluation of run-time performance of AES using a cryptography library developed for embedded systems, called Relic in a communication between two process in a general purpose Computer, between a general purpose Computer and a embedded system and between two embedded systems. It is considered the key sizes supported by the algorithm, the size of the transmitted data and the architecture used, also measuring the relation of the time spent by encryption and decryption and the total time for the secure communication. The results demonstrated that the architecture has a greater impact on the encryption and decryption times along with the message sizes. However, even for the communication between embedded systems, the percentage of the encryption and decryption time on the entire secure communication is smaller than 14%.

  • Case studies of performance evaluation of cryptographic algorithms for an embedded system and a general purpose Computer
    Journal of Network and Computer Applications, 2015
    Co-Authors: Natassya B. F. Silva, Daniel Fernando Pigatto, Paulo Martins, Kalinka Regina Lucas Jaquie Castelo Branco
    Abstract:

    Embedded systems are associations between hardware and software designed to perform a specific function. These systems are usually part of a larger system and their wireless communications are a hallmark. Therefore, it is important to guarantee a secure communication by ensuring the confidentiality of information, which is obtained through cryptography. Security has not traditionally been considered a requirement in embedded systems design and the application of specific security techniques to these devices is still incipient. This paper presents a performance evaluation analysis of cryptographic algorithms in embedded systems (namely RC2, AES, Blowfish, DES, 3DES, ECC and RSA). Parameters considered in the analysis are average processor and memory usage, response time and power consumption. The results show that symmetric and asymmetric algorithms such as Blowfish and ECC have a good performance in embedded systems when properly chosen for each situation.

L. Morris - One of the best experts on this subject based on the ideXlab platform.

  • ICASSP - An LPC k-parameter software speech synthesizer via dynamic microprogramming a general purpose Computer
    ICASSP '79. IEEE International Conference on Acoustics Speech and Signal Processing, 1
    Co-Authors: L. Morris, D. Allan
    Abstract:

    In a previous paper, it was shown that the presence of a combinatorial shifter in the data paths of a user microprogrammable general purpose Computer could be used for fast fixed-point multiplication if a unique microsubroutine was created for each required multiplier. A sixth-order direct form IIR digital filter was implemented via this technique. This work has been extended, so as to produce a tenth-order LPC k-parameter lattice synthesizer software system which executes in about 60% real time. The remaining CPU time may be allocated for k-parameter manipulation, as in synthesis-by-rule aAgorithms, or for unrelated computation. The approach used is novel since it involves dynamic analysis of k-parameters and creation of the microsubroutines required for synthesis during each pitch period. The results suggest that a high speed shifter embedded in an otherwise conventional micromachine architecture is Useful for practical, real-time digital signal processing applications.