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971.
In this paper particle swarm optimization is used to implement a synthesis procedure for cellular neural networks autoassociative memories. The use of this optimization technique allows a global search for computing the model parameters that identify designed memories, providing a synthesis procedure that takes into account the robustness of the solution. In particular, the design parameters can be modified during the convergence in order to guarantee minimum recall performances of the network in terms of robustness to noise overlapped to input patterns. Numerical results confirm the good performances of the designed networks when patterns are affected by different kinds of noise. 相似文献
972.
In the last years the amount of information being transmitted through communication networks has increased, and this has lead to an increased use of security protocols. The implementations of security protocols do not accurately follow the standards and this causes many malfunctions and security flaws. In this paper we will analyze the different approaches followed by the scientific community to evaluate security protocols' implementations, and will also analyze the special characteristics of security protocols, in order to deduce which are the key points for such an evaluation, how they can be evaluated and also if existing evaluation techniques can be used. 相似文献
973.
An optical strain measurement system for asphalt mixtures 总被引:1,自引:1,他引:0
Bjorn Birgisson Antonio Montepara Elena Romeo Riccardo Roncella Reynaldo Roque Gabriele Tebaldi 《Materials and Structures》2009,42(4):427-441
Knowledge of the conditions governing the initiation and propagation of cracks in hot mix asphalt (HMA) mixtures is a prerequisite
for a comprehensive understanding of HMA cracking mechanisms. Traditional strain measurement sensors have proved to be not
completely adequate in the sense that they do not provide pointwise measurements, thus not pinpointing the location of crack
initiation, and not accounting for non-uniform strain distributions. This paper presents a digital image correlation (DIC)
system for non-contact and full strain field measurements, conceived for the purpose of investigating the cracking behavior
of HMA mixtures. The whole system was developed so as to account for the special nature of typical HMA testing configurations.
An image matching technique (least squares matching) was employed for providing matches with sub-pixel accuracy. The performance
of the method was investigated by several tests. The DIC system was shown to overcome the shortcomings of traditional on-specimen
strain measurement devices achieving satisfactory accuracy compared to strain gauges. 相似文献
974.
J.S. Pérez Guerrero L.C.G. Pimentel T.H. Skaggs M.Th. van Genuchten 《International Journal of Heat and Mass Transfer》2009,52(13-14):3297-3304
This paper presents a formal exact solution of the linear advection–diffusion transport equation with constant coefficients for both transient and steady-state regimes. A classical mathematical substitution transforms the original advection–diffusion equation into an exclusively diffusive equation. The new diffusive problem is solved analytically using the classic version of Generalized Integral Transform Technique (GITT), resulting in an explicit formal solution. The new solution is shown to converge faster than a hybrid analytical–numerical solution previously obtained by applying the GITT directly to the advection–diffusion transport equation. 相似文献
975.
The recycled aggregates obtained from crushed waste concretes have different characteristics from those of natural aggregates. For that reason, the mixture proportions and the fresh and hardened properties of recycled concretes are different. The performance of recycled concrete exposed to high temperatures is not a very well-known subject since most studies have been conducted on conventional concretes. Recycled concretes with water/cement (w/c) ratios of 0.40 and 0.70, and made with three different types of natural coarse aggregate were exposed to 500 °C for 1 h. These concretes were evaluated by the ultrasonic method, resonance frequency, static modulus of elasticity and compressive strength, before and after heating, and compared with those obtained on similar conventional concretes containing the same type of natural coarse aggregate. The conventional and recycled concretes made with quartzitic coarse aggregate performed better after the heat treatment. 相似文献
976.
Antonio Falcó Amine Ammar Francisco Chinesta 《International Journal of Material Forming》2009,2(1):895
In this paper we study the problem of compute the solution of a linear system in a separable representation form. It arises in the discretized equations appearing in various physical domains, such as kinetic theory, statistical mechanics, quantum mechanics, and in nanoscience and nanotechnology among others. In particular, we use the fact that tensors of order 3 or higher have best rank-1 approximation. This fact allow to us to propose an iterative method based in the so-called by the signal processing community as the Matching Pursuit Algorithm, also known as Projection Pursuit by the statistics community or as a Pure Greedy Algorithm in the approximation theory community. We also give some numerical examples and describe its relationship with the Finite Element Method for High-Dimensional Partial Differential Equations based on the tensorial product of one-dimensional bases. We illustrate this situation taking as a model problem the multidimensional Poisson equation with homogeneous Dirichlet boundary condition. 相似文献
977.
New sulfur analogs of the sex pheromone of the female processionary mothThaumetopoea pityocampa have been found to be effective inhibitors of the natural pheromone activity both in EAG bioassays and field tests. The structures of these analogs have been derived from replacement of the oxygen atom(s) of the acetate group by sulfur (compounds 3-5) and the olefinic moiety of the enyne function by the isosteric SCH2 group (compounds 6 and 7). The synthesis and biological activity of 3-[(Z)-12-pentadecen-10-ynylthio]-1,1,1-trifluoropropan-2-one (8), a closely related structure to the pheromone is also described. 相似文献
978.
McCrae Robert R.; Costa Paul T. Jr.; Terracciano Antonio; Parker Wayne D.; Mills Carol J.; De Fruyt Filip; Mervielde Ivan 《Canadian Metallurgical Quarterly》2002,83(6):1456
Three studies were conducted to assess mean level changes in personality traits during adolescence. Versions of the Revised NEO Personality Inventory (P. T. Costa, Jr., & R. R. McCrae, 1992a) were used to assess the 5 major personality factors. A 4-year longitudinal study of intellectually gifted students (N = 230) was supplemented by cross-sectional studies of nonselected American (N = 1,959) and Flemish (N = 789) adolescents. Personality factors were reasonably invariant across ages, although rank-order stability of individual differences was low. Neuroticism appeared to increase in girls, and Openness to Experience increased in both boys and girls; mean levels of Extraversion, Agreeableness, and Conscientiousness were stable. Results extend knowledge of the developmental curve of penalty traits backward from adulthood and help bridge the gap with child temperament studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
979.
980.
López-Rubio Ezequiel Muñoz-Pérez José Antonio Gómez-Ruiz José 《Neural Processing Letters》2002,16(2):93-109
We propose a new self-organizing neural model that considers a dynamic topology among neurons. This leads to greater plasticity with respect to the self-organizing neural network (SOFM). Theorems are presented and proved that ensure the stability of the network and its ability to represent the input distribution. Finally, simulation results are shown to demonstrate the performance of the model, with an application to colour image compression. 相似文献