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991.
纹理分析中往往将彩色图像转换为灰度图以降低计算复杂度,这样就忽略了颜色信息。而利用主成分分析
的方法来降维彩色纹理,则可以尽可能地保留颜色和纹理信息。高斯图模型(Uaussian Graphical Models, GGM)可以
很好地描述有交互作用的高维数据,因此可用来建立图像纹理模型。根据局部马尔可夫性和高斯变量的条件回归之
间的关系,可将复杂的模型选择转变为较简单的变量选择。通过惩罚正则化方法,其部域选择和参数佑计可同步进
行,然后提取纹理特征进行彩色纹理分类,实验显示其具有很好的效果。因此,结合主成分分析和高斯图模型来构建
彩色纹理模型有很好的发展前景。 相似文献
992.
一种基于UMTS核心网的定时器实现方案 总被引:1,自引:0,他引:1
针对UMTS核心网呼叫连接协议的实现,提出了一种软件定时器的实现方案。该方案以WinCE实时嵌入式系统作为开发环境,采用单链表队列和相对时间项方式的定时器数据结构,基于时间相对算法建立了定时器单一线程和插入、删除程序,以实现协议所规定的多定时器逻辑功能。在嵌入式系统编程过程中,运用互斥量机制完成定时器线程与插入、删除程序的通信同步;运用堆管理机制完成系统内存的动态分配与释放。对该方案的主要技术和实现结构作了论述,并给出了关键代码;还对UMTS协议结构和WinCE相关机制作了分析。实验表明,该设计方案具有编程效率高、实时性能好和系统开销小的特点,适合基于嵌入式系统的通信协议定时器编程。 相似文献
993.
传感器输出特性的线性化回归程序设计 总被引:2,自引:1,他引:1
介绍了用面向对象程序设计方法编制的线性回归数据处理程序 ,该程序用于传感器实验数据的回归处理和特性曲线的绘制 相似文献
994.
BLISS/S: a new method for two-level structural optimization 总被引:4,自引:2,他引:2
J. Sobieszczanski-Sobieski S. Kodiyalam 《Structural and Multidisciplinary Optimization》2001,23(1):1-13
The paper describes a two-level method for structural optimization for a minimum weight under the local strength and displacement
constraints. The method divides the optimization task into separate optimizations of the individual substructures (in the
extreme, the individual components) coordinated by the assembled structure optimization. The substructure optimizations use
local cross-sections as design variables and satisfy the highly nonlinear local constraints of strength and buckling. The
design variables in the assembled structure optimization govern the structure overall shape and handle the displacement constraints.
The assembled structure objective function is the objective in each of the above optimizations. The substructure optimizations
are linked to the assembled structure optimization by the sensitivity derivatives. The method was derived from a previously
reported two-level optimization method for engineering systems, e.g. aerospace vehicles, that comprise interacting modules
to be optimized independently, coordination provided by a system-level optimization. This scheme was adapted to structural
optimization by treating each substructure as a module in a system, and using the standard finite element analysis as the
system analysis. A numerical example, a hub structure framework, is provided to show the new method agreement with a standard,
no-decomposition optimization. The new method advantage lies primarily in the autonomy of the individual substructure optimization
that enables concurrency of execution to compress the overall task elapsed time. The advantage increases with the magnitude
of that task.
Received December 5, 1999?Revised mansucript received April 26, 2000 相似文献
995.
This paper presents an integrated approach that supports the topology optimization and CAD-based shape optimization. The main
contribution of the paper is using the geometric reconstruction technique that is mathematically sound and error bounded for
creating solid models of the topologically optimized structures with smooth geometric boundary. This geometric reconstruction
method extends the integration to 3-D applications. In addition, commercial Computer-Aided Design (CAD), finite element analysis
(FEA), optimization, and application software tools are incorporated to support the integrated optimization process. The integration
is carried out by first converting the geometry of the topologically optimized structure into smooth and parametric B-spline
curves and surfaces. The B-spline curves and surfaces are then imported into a parametric CAD environment to build solid models
of the structure. The control point movements of the B-spline curves or surfaces are defined as design variables for shape
optimization, in which CAD-based design velocity field computations, design sensitivity analysis (DSA), and nonlinear programming
are performed. Both 2-D plane stress and 3-D solid examples are presented to demonstrate the proposed approach.
Received January 27, 2000
Communicated by J. Sobieski 相似文献
996.
The necessary and sufficient conditions for global optimality are derived for an eigenvalue optimization problem. We consider
the generalized eigenvalue problem where real symmetric matrices on both sides are linear functions of design variables. In
this case, a minimization problem with eigenvalue constraints can be formulated as Semi-Definite Programming (SDP). From the
Karush-Kuhn-Tucker conditions of SDP, the necessary and sufficient conditions are derived for arbitrary multiplicity of the
lowest eigenvalues for the case where important lower bound constraints are considered for the design variables.
Received May 18, 2000 相似文献
997.
An optimal design method based on the concepts of Transferred Forces is introduced. The method uses these forces in an indirect
way. The concept of reaction functional based on transferred forces is introduced. The functional approximates the structural
behaviour in terms of the properties of a selected region. Using the reaction functionals, a nonlinear programming formulation
and a computational method that perform sizing and topology optimization are developed. The procedure does not need structural
analyses during optimization iterations. Example problems are solved with the method and the similar solutions are obtained
for a refined mesh model and a different starting design. Thus, it is concluded that the new concept presented here is applicable
to structural optimization problems.
Received June 28, 2000 相似文献
998.
This paper deals with a global optimization scheme for structural systems that require finite element analysis to evaluate
the constraints or the objective function. The paper proposes a strategy for finding the global optimum using an interval
method in conjunction with a multipoint function approximation. The highly nonlinear and nonconvex objective and constraint
functions are first represented in the design space using linear and adaptive local approximations and these approximations
are blended globally with the use of proper weighting functions. The interval method is then employed to trace the global
optimum in the approximated function space. The procedure is tested with several examples with known global solutions and
it is successfully applied to optimize the fiber-orientation angles of laminated composite plates for minimum deflections.
Received December 22, 2000 相似文献
999.
There has been recent interest in exploring alternative computational models for structural analysis that are better suited
for a design environment requiring repetitive analysis. The need for such models is brought about by significant increases
in computer processing speeds, realized primarily through parallel processing. To take full advantage of such parallel machines,
however, the computational approach itself must be revisited from a totally different perspective; parallelization of inherently
serial paradigms is subject to limitations introduced by a requirement of information coordination. The cellular automata
(CA) model of decentralized computations provides one such approach which is ideally tailored for parallel computers. The
proposed paper examines the applicability of the cellular automata model in problems of 2-D elasticity. The focus of the paper
is in the use of a genetic algorithm based optimization process to derive the rules for local interaction required in evolving
the cellular automata.
Received August 28, 2000 相似文献
1000.