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51.
Gloria Galan-Marin Enrique Merida-Casermeiro Domingo Lopez-Rodriguez 《Neural Processing Letters》2007,26(2):133-143
Detection of isomorphism among kinematic chains is essential in mechanical design, but difficult and computationally expensive.
It has been shown that both traditional methods and previously presented neural networks still have a lot to be desired in
aspects such as simplifying procedure of identification and adapting automatic computation. Therefore, a new algorithm based
on a competitive Hopfield network is developed for automatic computation in the kinematic chain isomorphism problem. The neural
approach provides directly interpretable solutions and does not demand tuning of parameters. We have tested the algorithm
by solving problems reported in the recent mechanical literature. Simulation results show the effectiveness of the network
that rapidly identifies isomorphic kinematic chains. 相似文献
52.
Barrier options are financial derivative contracts that are activated or deactivated according to the crossing of specified
barriers by an underlying asset price. Exact models for pricing barrier options assume continuous monitoring of the underlying
dynamics, usually a stock price. Barrier options in traded markets, however, nearly always assume less frequent observation,
e.g. daily or weekly. These situations require approximate solutions to the pricing problem. We present a new approach to
pricing such discretely monitored barrier options that may be applied in many realistic situations. In particular, we study
daily monitored up-and-out call options of the European type with a single underlying stock. The approach is based on numerical
approximation of the transition probability density associated with the stochastic differential equation describing the stock
price dynamics, and provides accurate results in less than one second whenever a contract expires in a year or less. The flexibility
of the method permits more complex underlying dynamics than the Black and Scholes paradigm, and its relative simplicity renders
it quite easy to implement. 相似文献
53.
We study the behavior of disk assemblies with a variable disorder distribution. The packing is first consolidated and then continuously tilted very slowly. The amount of displaced disks for each tilted angle is recorded. Large displacements of the disks can occur due to some local or global mechanical instabilities. The definition of neighboring disks is based on radical (extension of Voronoï) tessellation rules to decompose, in a unique and perfectly defined manner, the two-dimensional space for polydisperse disks. In this way, by comparing the characteristics of stability for one disk to the neighboring ones for local ordered cluster, we can predict the global amount of displaced disks. Some tilting cycles have been performed to check the correlation between the instability of the packing structure (collective displacements) with micro and macro order parameters. 相似文献
54.
Wood inspection with non-supervised clustering 总被引:9,自引:0,他引:9
Abstract. The appearance of sawn timber has huge natural variations that the human inspector easily compensates for mentally when determining
the types of defects and the grade of each board. However, for automatic wood inspection systems these variations are a major
source for complication. This makes it difficult to use textbook methodologies for visual inspection. These methodologies
generally aim at systems that are trained in a supervised manner with samples of defects and good material, but selecting
and labeling the samples is an error-prone process that limits the accuracy that can be achieved. We present a non-supervised
clustering-based approach for detecting and recognizing defects in lumber boards. A key idea is to employ a self-organizing
map (SOM) for discriminating between sound wood and defects. Human involvement needed for training is minimal. The approach
has been tested with color images of lumber boards, and the achieved false detection and error escape rates are low. The approach
also provides a self-intuitive visual user interface.
Received: 16 December 2000 / Accepted: 8 December 2001
Correspondence to: O. Silvén 相似文献
55.
介绍带状大比例尺地形图在分带处高斯平面上拼接的原理和方法,并编制了相应的接边数据处理程序。作业实践说明,该接边方法简便实用,计算程序正确可靠。 相似文献
56.
Because of the widespread increasing application of Web services and autonomic computing, self-adaptive software is an area gaining increasing importance. Control theory provides a theoretical foundation for self-adaptive software. In this paper, we propose the use of the supervisory control theory of discrete event dynamic systems (DEDS) to provide a rigorous foundation for designing software for reactive systems. This paper focuses in particular on design of software with an attractivity requirement. It studies this problem using the polynomial dynamic system (PDS) model of DEDS. A necessary and sufficient condition for software existence and two algorithms for such software design are presented. 相似文献
57.
Modeling the effect of pigment morphology on the dynamic compression of coating layers using DEM 总被引:2,自引:1,他引:1
In the present paper, discrete element method (DEM) was employed to investigate the effect of pigment morphology on packing dynamics and compressive behavior of paper coating layers in calendering process. Spherical, platy, and needle-like particles, representing GCC, delaminated clay, and aragonite PCC pigments, were considered in this study. For each particle shape, the compression of coating structures formed by mono-sized and poly-dispersed pigments were modeled. Stress–strain behavior of the coating layers and in-plane and out-of-plane movements of the pigment particles during the compression were computed under the same maximum compressive stress. Simulation results revealed that the in-plane movements of the pigment particles during compression in the calender nip were small in magnitude (<0.35 μm). These findings help to better understand the smoothening phenomena of coating structures during the calendering process. 相似文献
58.
ROI-based Watermarking Scheme for JPEG 2000 总被引:1,自引:0,他引:1
Yu-Cheng Fan Arvin Chiang Jan-Hung Shen 《Circuits, Systems, and Signal Processing》2008,27(5):763-774
A new region of interest (ROI)-based watermarking method for JPEG 2000 is presented. The watermark is embedded into the host
image based on the characteristics of the ROI to protect rights to the images. This scheme integrates the watermarking process
with JPEG 2000 compression procedures. Experimental results have demonstrated that the proposed watermark technique successfully
survives JPEG 2000 compression, progressive transmission, and principal attacks. 相似文献
59.
This paper presents the Navigation Maps Modeling approach (NMM), which provides platform independent models for characterizing navigation maps of web applications. The NMM approach is conceived to obtain a trade off between high and low-level design notations. As high-level design notations, NMM models permit architectural details that may hinder the overall understanding of the web application to be left out. As low-level design notations, NMM models can easily be transformed into detailed architectural designs, which are very valuable at coding and maintenance stages. 相似文献
60.
本文将用数学和实验两种方法证实MC~2电缆不仅能保证特性阻抗变化不超出电缆技术规范。而且能保证在设计频率范围内电缆结构反射损耗最小。 相似文献