共查询到20条相似文献,搜索用时 15 毫秒
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为了提高空间相机在力/热双重环境条件下的系统稳定性,同时能够实现系统的轻量化目标,在某型空间相机的研制过程中选用了具有高比刚度和热稳定性的高体份SiC/Al复合材料。采用整体式框架结构,将基于变密度法的连续体结构拓扑优化方法应用到相机框架结构的初始设计中,通过设定相应的约束条件和目标函数,进行迭代求解,得到了相机框架分别在X、Y、Z三个方向重力作用下的结构拓扑优化结果,结合工艺要求,最终确定了空间相机框架的设计方案。通过与对比方案比较发现,经过拓扑优化所得到的框架结构在结构刚度及轻量化率上都有明显提高,实现了空间相机框架高刚度、轻量化的设计目标。 相似文献
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Biranchinath Sahu 《Microelectronics Journal》2002,33(3):253-264
In this work, we have used the concept of fuzzy logic to build a CAD tool for the parametric optimization of MOS operational amplifiers (op-amps). In order to capture human intentions to express the requirements for a particular application, e.g. minimize power, maximize gain, etc., each of the performance specifications of a given topology is assigned a membership function to measure the degree of fulfillment of the objectives and the constraints. A number of objectives are optimized simultaneously by assigning weights to each of them representing their relative importance, and then by clustering them to form the objective function, which is solved by Powell's direct search algorithm. After optimization, the program creates a SPICE netlist of the circuit topology for the verification of the design. Initially, this approach was used for parametric optimization of simple bipolar and MOS circuits, e.g. current mirrors, gain stages, differential amplifiers, etc. Encouraged by these results, it was applied to much more complex blocks, such as op-amps. The design results obtained from our optimization program showed an excellent agreement with those obtained from SPICE simulation for the op-amp topologies considered in this work. 相似文献
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针对现有的独立成分分析法分离混合混沌信号精度不理想的问题,提出了一种新的混沌信号盲分离方法。该方法以求解最优解混矩阵为目标,利用峭度构造目标函数,将混沌信号的盲源分离转化为一个优化问题,并用萤火虫算法求解。同时,通过预白化和正交矩阵的参数化表示降低优化问题的维数,能有效提高分离精度。仿真结果表明,无论是处理混合的混沌映射信号还是混合的混沌流信号,该方法都能快速收敛,并且其分离精度在各项实验中都优于独立成分分析法等现有的盲源分离方法。 相似文献
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为了加强配电网自动化技术课程建设,提出基于虚实协同配合的实验教学方案。以“情景互动、探究创新”为实验教学理念,将课堂理论、虚拟仿真和物理仿真三者紧密结合。从需求导向出发,设计了四个渐进式实验,通过沉浸式教学,让学生了解配电网和开关设备的结构形态,掌握配电网运行、故障与保护算法的原理,培养学生的创新思维和创新设计能力。最后,建立主、客观评价相结合的综合评价体系,对学生参与实验的每个环节进行评价,通过收集反馈信息,持续改进评价体系。 相似文献
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In this paper, a novel method is proposed to address the problem of designing virtual topology over wavelength division multiplexing (WDM) networks under bandwidth demand uncertainties. And a bandwidth demand model under uncertainties is presented. The optimization goal of virtual topology design is defined as minimizing the maximum value amongp percentiles of the bandwidth demand distribution on all Hght-paths. Correspondingly, we propose a heuristic algorithm called an improved decreasing multi-hop logical topology design algorithm (ID-MLTDA) that involves with a degree of uncertainties to design virtual topology. The proposed algorithm yields better performance than previous algorithms. Additionally, the simplicity and efficiency of the proposed algorithm can be in favor of the feasibility for topology design of large networks. 相似文献
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S. Aalto I. Norros J. T. Virtamo J. L. van den Berg E. Smeitink 《Telecommunication Systems》1996,5(1):159-175
Connectionless service such as SMDS, or its European equivalent CBDS, can be provided by an ATM network by building a separate connectionless overlay network (CLON) on top of the ATM bearer service. A CLON is composed of a number of connectionless servers, CLSs, which provide the routing function, connected by semipermanent virtual paths (VPs). In this paper, architectural issues related to the design of a CLON are studied. In particular, we address the question of the optimal number of CLSs and their interconnection topology, assuming the underlying ATM network and the mean connectionless traffic load are known. The objective of the design process is to meet given design criteria with minimum costs. The QoS requirements of the SMDS/CBDS service are briefly reviewed and a simple cost model for the CLON network is given. The dimensioning of the logical links is also considered. Then the design process to find the optimal solution for the whole network is outlined. A simplified procedure was applied in numerical studies of the topological optimization. In order to find the general dependence of the optimal number of CLSs on the size of the network and other network parameters, the optimization procedure was applied to a large number of sample ATM networks, generated by an algorithm which is briefly described. Results from these studies are presented and discussed. 相似文献
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In this paper, we describe an algorithm for designing local-area networks (LANs) with the objective of minimizing the average network delay. The topology design includes issues such as determination of the number of segments in the network, allocating the users to the different segments, and determining the interconnections and routing among the segments. The determination of the optimal LAN topology is a very complicated combinatorial optimization problem. Therefore, a heuristic algorithm that is based on genetic ideas is used. Numerical examples are provided and the quality of the designs obtained by using the algorithm is compared with lower bounds on the average network delay that are developed 相似文献
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为满足镜筒结构高强度、轻量化及良好的热环境适应性的要求,研究了多工况下同时考虑结构刚度和一阶固有频率的多目标优化问题。首先,基于变密度连续体结构拓扑优化方法,采用加权和法和靶向量法定义了多工况下多目标优化函数;然后进行了镜筒的优化设计。整个优化设计包括拓扑优化和厚度优化两部分。在拓扑优化中,以刚度和频率最大为目标函数,得到了满足要求的镜筒结构材料的最佳分布,并以此为依据,完成了镜筒结构的三维建模;以拓扑优化所得结构的柔度值和一阶频率为约束,质量最小为目标函数,对镜筒结构各厚度进行了优化。优化设计结果表明,镜筒质量由18.63 kg减少至12.46 kg;重力作用下最大变形由0.013 mm减少至0.001 9 mm;热载荷作用下最大变形由0.098 mm减少至0.062 mm;一阶固有频率从65.6 Hz提高至189.83 Hz。该优化设计方法有效缩短了设计周期,提高了镜筒结构的性能,满足了系统设计要求。 相似文献
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基于增强现实的动态红外场景仿真系统设计研究 总被引:1,自引:0,他引:1
传统的仿真技术会受算法的复杂度、运算能力及接口等的限制。针对这一问题,设计了一种基于增强现实的思想在真实图像上进行实时动态红外场景仿真的系统。首先使用3DS MAX生成虚拟目标模型,再对虚拟目标模型进行几何一致性变换和红外辐射一致性变换,使用SURF-ORB特征匹配对探测器的运动姿态进行跟踪,最终通过光栅渲染使虚拟目标与真实场景进行虚实融合,完成基于增强现实的动态红外场景仿真系统的设计。实验结果显示,该系统能够实现高帧频、高真实性的红外仿真图像,具有较强的可扩展性。 相似文献
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针对线性混合模型在实际高光谱图像解混过程中的局限性,提出一种新的基于微分搜索的非线性高光谱图像解混算法.在广义双线性模型的基础上采用重构误差作为解混的目标函数,将非线性解混问题转化为最优化问题.将目标函数中的待求参数映射为微分搜索过程中的位置变量,利用微分搜索算法对目标函数进行优化求解.在求解过程中,通过执行搜索范围控制等机制满足高光谱图像解混的约束要求,进而求得丰度系数和非线性参数,实现非线性高光谱图像解混.仿真数据和真实遥感数据实验结果表明,所提出的非线性解混算法可以有效克服线性模型下解混算法的局限性,避免了由于使用梯度类优化方法而易陷入局部收敛的问题,较之其它高光谱图像解混算法具有更好的解混精度. 相似文献
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This paper presents an improved weighted least squares (WLS) algorithm for the design of quadrature mirror filters (QMFs), First, a new term is incorporated into the objective function that effectively prevents an optimization algorithm from producing suboptimal QMFs. These suboptimal QMFs exhibit a transition band anomaly; the frequency responses of the filters have large oscillatory components in the transition band. The new term can be applied to the WLS design of any FIR filter to prevent a similar transition band anomaly. Next, we present an algorithm to obtain the QMF coefficients that minimize the objective function incorporating the new term. The computational requirement of this algorithm is also briefly discussed. Last, we include a set of practical design rules for use with our algorithm. These rules simplify the design process by providing good estimation of the design parameters, such as the minimum filter length, to meet a given set of QMF specifications 相似文献
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This paper studies a traffic grooming in wavelength-division multiplexing (WDM) mesh networks for the SONET/SDH streams requested between node pairs. The traffic could be groomed at the access node before converting to an optical signal carried in the all-optical network. We design a virtual topology with a given physical topology to satisfy multiple objectives and constraints. The grooming problem of a static demand is considered as an optimization problem. The traditional algorithms found in the literatures mostly focus on a single objective either to maximize the performance or to minimize the cost. We propose a multi-objective evolutionary algorithm to solve a grooming problem that optimizes multiple objectives all together at the same time. In this paper we consider the optimization of three objectives: maximize the traffic throughput, minimize the number of transceivers, and minimize the average propagation delay or average hop counts. The simulation results show that our approach is superior to an existing heuristic approaches in an acceptable running time. 相似文献
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为了进一步提升高光谱图像的解混精度,提出一种基于回溯优化的高光谱图像后非线性解混算法。在后非线性混合模型的基础上,以观测图像与重构图像之间的重构误差为目标函数,使用回溯搜索算法在解空间搜索使目标函数取得极小值的最优解。在搜索过程中,利用回溯搜索算法的边界控制机制有效保证了高光谱图像解混过程中的约束条件,进而有效实现了对解混丰度值和非线性参数的精确估计。针对合成高光谱图像和真实高光谱遥感图像的解混实验表明,文中算法具有优异的解混性能,所达到的解混精度显著优于现有非线性高光谱图像解混算法。 相似文献
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Bo Liu Author Vitae Author Vitae Zhiping Yu Author Vitae Author Vitae Miao Li Author Vitae Author Vitae Jing Lu Author Vitae Author Vitae 《Integration, the VLSI Journal》2009,42(2):137-148
This paper investigates a hybrid evolutionary-based design system for automated sizing of analog integrated circuits (ICs). A new algorithm, called competitive co-evolutionary differential evolution (CODE), is proposed to design analog ICs with practical user-defined specifications. On the basis of the combination of HSPICE and MATLAB, the system links circuit performances, evaluated through electrical simulation, to the optimization system in the MATLAB environment, once a circuit topology is selected. The system has been tested by typical and hard-to-design cases, such as complex analog blocks with stringent design requirements. The results show that the design specifications are closely met, even in highly-constrained situations. Comparisons with available methods like genetic algorithms and differential evolution, which use static penalty functions to handle design constraints, have also been carried out, showing that the proposed algorithm offers important advantages in terms of optimization quality and robustness. Moreover, the algorithm is shown to be efficient. 相似文献
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MOMS-GA: A Multi-Objective Multi-State Genetic Algorithm for System Reliability Optimization Design Problems 总被引:1,自引:0,他引:1
A custom genetic algorithm was developed and implemented to solve multiple objective multi-state reliability optimization design problems. Many real-world engineering design problems are multi-objective in nature, and among those, several of them have various levels of system performance ranging from perfectly functioning to completely failed. This multi-objective genetic algorithm uses the universal moment generating function approach to evaluate the different reliability or availability indices of the system. The components are characterized by having different performance levels, cost, weight, and reliability. The solution to the multi-objective multi-state problem is a set of solutions, known as the Pareto-front, from which the analyst may choose one solution for system implementation. Two illustrative examples are presented to show the performance of the algorithm; and the multi-objective formulation considered for both of them is the maximization of system availability, and the minimization of both system cost, and weight. 相似文献
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动态电力经济调度(Dynamic Economic Dispatch,DED)属于一种在时间和空间上相互耦合的多阶段动态决策问题,一般被转化为一个高维的约束数值优化问题来求解.本文提出了一种新型全局优化算法--类进化算法(Cluster Evolutionary Algorithm,CEA),并将其应用于DED问题的计算.CEA通过聚类过程在进化个体间构建一定结构的连接关系,并利用这种虚拟的簇类化组织来协调和控制群体的优化计算过程,提高算法对高维问题空间的搜索效率和抗早熟能力.在仿真实验中2个DED测试系统被用于对CEA的性能进行检验,其所得最佳计算结果要好于目前已报道的最优解,而实验统计数据则显示CEA是一种求解DED问题可行且有效的方法. 相似文献