基于Voronoi图和遗传算法的航迹规划

面对复杂的作战环境,如何快速地规划出满足约束条件的飞行轨迹,是实现无人机突防攻击的关键.提出了一种基于Voronoi图和改进遗传算法的航迹规划方法,该方法采取分层规划的思想,首先由Voronoi图生成初始航迹,并综合考虑约束条件,赋予各条航迹相应的权值;然后采用遗传算法在生成的航迹空间中寻优, 从而得到满意的航迹.为避免产生不可行解,采取了基于优先级编码的改进遗传算法,详细介绍了其编码与解码原理,并给出了相应的操作算子.仿真结果表明,整个航迹规划的思路是可行的.     

神经网络优化特性中一些问题的研究

本文研究了一类神经网络优化特性的一些问题.对其解的特性、可行解空间的划分及吸引区特性进行了研究.     

求解Job shop的一种快速混合算法

结合车间调度问题本身的特点,采用关键路径块邻域结构,混合禁忌搜索算法和粒子群优化算法,设计了一种快速混合调度算法.该算法对预选择的块邻域解的性能进行快速估计,对不可行解尽早舍去,大大减小了邻域解的搜索空间.仿真结果表明,该算法在求解平均时间和性能方面均具备明显优势.     

改进的用于半导体器件综合系统的遗传算法

本文对应用于器件综合系统的遗传算法GENOCOP进行了改进.将实数设计空间根据参数的工艺精度影响转换为整型空间,并加入适应性复合算子利用已经得到的点来扩展和开发准可行空间.使其保持有效搜索到可行解的特性的同时,在同等的算法设置下,提高了对可行空间的覆盖率(约2.87倍),可以帮助设计人员更有效的设计可工作的器件.     

多加性QoS约束下的链路分离路由算法

对多个加性QoS约束下的链路分离路径问题进行了研究,针对现有算法求解结果依赖于网络结构,难以保证对任意网络都可求得可行解和最优解的问题,提出了一种与网络结构无关的多约束链路分离路径路由算法(MCLPRA,multiple constrained link-disjoint path routing algorithm).该算法基于SAMCRA,采用对解空间先分类,然后按类进行处理和搜索的方法,引入了控制搜索深度的参数,可保证对任意网络都能求得可行解.理论分析表明,MCLPRA能够在现有算法不能求解的情况下解得可行解和最优解.仿真结果显示,MCLPRA的可行解平均求解成功率明显高于现有算法且所求路径对长度也比现有算法更短.     

求解约束优化的一种新的进化算法

罚函数法是解决约束优化最常用的方法,但如何确定罚因子是其难以克服与回避的问题.该文提出的求解约束优化问题的新的进化算法克服了这一困难,其基本思想是对种群中的个体按可行和不可行分别采取两种评价方案,对可行解按其目标函数值的大小加以评价,对不可行解按其违反约束的程度进行评价.作为评价个体优劣的适应度函数将可行点映射到(-1,1),将不可行点映射到(1,2),这样有效地区分了可行点与不可行点.数据实验与比较结果表明了该算法的有效性.     

分布式视频编码边信息改进技术

高质量的边信息生成技术是分布式视频编码系统实现高压缩效率的关键所在.提出一种边信息的改进方法,对部分译码的Wyner-Ziv(WZ)帧中运动剧烈的区域进行空域修正,使用相邻关键帧对应块的空间预测值与实际值之间的差值来补偿当前部分译码WZ帧中空间预测的误差.仿真结果表明该方法提升了边信息的质量,进而提高了DVC系统的率失真性能.     

调度问题及其解空间的特征分析

目前,在组合优化领域中,评判近优算法的性能尚缺乏统一的标准和有效的依据,而算法的效率与所要解决问题之间的关系密不可分.本文以JSP问题为例,研究了调度问题本身的结构特征,分析了调度问题可行解空间的属性,提出了分割因子的概念.研究表明,分割因子影响调度问题可行解空间的规模,而各工序加工时间的分布则影响解空间的"崎岖"状况;分割因子和工件加工时间的分布在一定程度上可以反映调度问题的复杂程度.这对近优算法的设计具有一定的指导意义,并为建立统一的近优算法效率衡量标准迈出了探索性的一步.     

基于模拟退火算法的平面稀疏阵优化

大规模稀疏阵列优化时,解空间十分庞大,一般优化算法难以实现.模拟退火算法不是一种解空间遍历算法,因而非常适合用于解决此类问题.利用平面阵的对称性,对解空间进行镜像压缩,进一步提高了优化效率.利用解空间压缩后的模拟退火算法优化得到了一种副瓣特性优良的稀疏布阵方式.     

通信网中链路重要性的评价方法

本文提出了一种通信网链路重要性的评价方法,该方法可以评价全网范围内的链路重要性.最重要的链路是将其进行边收缩操作后,得到的图的生成树数目最多.通过比较生成树的数目,我们可以判断通信网中任意两条链路的相对重要性.基于生成树数目的边收缩方法反映了某条链路处于正常工作时,对整个通信网的贡献大小.实验结果和理论分析均证明了该方法的有效性和可行性.     

Alkaline cleaning of silicon wafers: additives for the prevention of metal contamination

The paper presents a new strategy for cleaning of silicon wafers. A novel class of chelating agents added to alkaline cleaning mixtures provides promising performance without negative effects such as metal redeposition due to residual metal contamination of the cleaning solution. The superior capability of the new cleaning process is confirmed by the results obtained from wafer surface metal analysis as well as from minority carrier lifetime and diffusion length measurements and gate oxide integrity tests. Particle densities and surface roughness are not influenced by the presence of the chelating agents in the cleaning solution. TOF–SIMS measurements do not indicate any deposition of chelating agent on the wafer surface. With this type of modified SC-1 cleaning procedure the acid SC-2 step used in conventional RCA cleans to remove the metals deposited in the preceding SC-1 step is unnecessary resulting in substantial cost savings with respect to chemicals, waste, equipment and space.     

基于圆半径动态调节的网格划分算法

利用圆半径的动态调节算法划分散乱数据点生成三角形网格,通过调节圆半径的大小来控制生成曲面的质量,易于实现,但算法不擅长处理实体表面存在的台阶边缘。采用将空间数据点转化成二维图像并分区域,在每个区域内划分三角形网格的方法来解决这个问题。通过对比实验结果,重建效果良好,对台阶边缘具有较好的处理能力。     

Higher order impedance boundary conditions applied to scattering bycoated bodies of revolution

In this paper higher order impedance boundary conditions will be employed in the solution of scattering by coated conducting bodies of revolution. The higher order impedance solution reduces the total number of unknowns relative to the exact solution, and produces a system matrix which is less dense than that of the exact solution. The construction of the solution involves two distinct steps. In the first step the body of revolution is replaced by an equivalent set of electric and magnetic currents on its exterior surface which generate the true fields outside the body. An integral equation relating these currents through the free space Green's function is derived. Step two employs the higher order impedance boundary condition to relate the electric and magnetic currents on the surface of the body. This replaces the rigorous solution of the interior problem. The higher order impedance boundary conditions are derived by obtaining an exact impedance boundary condition in the spectral domain for the coated ground plane, approximating the impedances as ratios of polynomials in the transform variables, and employing the Fourier transform. The resulting spatial domain differential equations are solved in conjunction with the integral equation using the method of moments. Several examples of bistatic and monostatic radar cross section for coated bodies of revolution are used to illustrate the accuracy of the higher order impedance boundary condition solution relative to the standard impedance boundary condition solution and the exact solution. The effects of coating thickness, loss, and curvature on the accuracy of the solution are discussed     

微腐蚀去除硅衬底表面损伤及污染物研究

硅片CMP工艺会引入表面缺陷和沾污,通常采用NaOH和KOH作为腐蚀溶液,利用微腐蚀法将硅片表面的损伤污染层剥离,以免导致IC制备过程中产生二次缺陷,但会不可避免地引入金属离子。制备了一种用螯合剂和表面活性剂复配的新型清洗液,利用螯合剂对硅片表面损伤层进行微腐蚀,同时采用表面活性剂去除硅片表面吸附的微粒。经台阶仪和原子力显微镜检测,该清洗液能有效去除硅片表面损伤层和颗粒,同时螯合剂本身不含金属离子,并且对金属离子有螯合作用,可有效避免传统腐蚀液中金属离子带来的二次污染。     

一种基于高阶统计量的相空间重构方法

利用混沌理论进行信号处理的第一步就是对混沌信号进行相空间重构,Tekens提出的延迟坐标法奠定了相空间重构的基础,而重构参数的选择则成为主要的难题。本文在比较了现有的参数选择方法的基础上,提出了一种基于高阶统计量的相空间重构方法,通过仿真证明,该方法具有较好的重构效果。     

Plane wave diffraction by an impedance step

Plane wave diffraction by two half-planes joined by a step is studied in the case where the half-planes and the step are characterized by different surface impedances. The diffraction problem is first reduced to a modified Wiener-Hopf equation of the second kind whose solution contains an infinite set of constants satisfying an infinite system of linear algebraic equations. A numerical solution of this system is obtained for various values of the surface impedances and the height of the step, through which the effect of these parameters on the diffraction phenomenon is studied     

基于柱坐标抛物方程的海上雷达覆盖范围研究

为预测雷达波在海面的全向传播特性,提出了基于柱坐标抛物方程(parabolic equation,PE)的电波传播模型,用于海上雷达覆盖范围的研究.从亥姆霍兹方程出发,推导出柱坐标系下的前向PE形式.再利用PE通解中三角函数的正交性,求解各电波传播模式的激励系数,结合分步傅里叶变换实现柱坐标PE的步进迭代算法,以预测电...     

高空间照明均匀度植物光源系统的设计

传统的植物照明设计只针对单一参考面均匀度进行评价，难以满足植物在整个生长过程中对均匀光照环境的需求。针对这一问题，首先提出了空间照明均匀度评价体系，并基于该体系设计了一种复合光源模块的立体化照明系统，以期构建照明均匀的植物生长空间。进一步利用Taguchi方法优化实验过程，在结合ANOVA分析的基础上，获得了最优结构参数。最后对所得最优解进行灯珠形状分析和植物生长过程中的照明效果测试。实验结果表明:最优结构可提供一个水平参考面照度均匀度为87.22%，混色均匀度为90.11%；竖直参考面照度均匀度93.02%，混色均匀度91.43%的均匀照明空间。该植物光源系统可满足植物生长过程中对均匀空间照明环境的需求。     

TIPS-pentacene crystalline thin film growth

The crystalline film growth of TIPS-pentacene thin films by confined solution deposition is investigated. The crystalline thin films grow dendritic in the initial stage and continue to grow to elongated plate-like crystals when the solution is deposited in a confined space in-plane. The majority of the thin film, containing smaller thin crystals, is formed within the first 10 s after depositing the solution and continues to grow in minutes to millimeter sized single crystals. By atomic force microscopy we show that impurities are expelled by the growing crystals and clusters accumulate at step edges on the surface of the larger crystals. The influence of crystal thickness and orientation on the electronic transport in field-effect transistors is studied, and shows an optimum performance for devices with thin elongated crystals that are aligned parallel to the electric field between the source–drain electrodes.     

GaAs surface wet cleaning by a novel treatment in revolving ultrasonic atomization solution

A novel process for the wet cleaning of GaAs surface is presented. It is designed for technological simplicity and minimum damage generated within the GaAs surface. It combines GaAs cleaning with three conditions consisting of (1) removal of thermodynamically unstable species and (2) surface oxide layers must be completely removed after thermal cleaning, and (3) a smooth surface must be provided. Revolving ultrasonic atomization technology is adopted in the cleaning process. At first impurity removal is achieved by organic solvents; second NH_4OH : H_2O_2 : H_2O =1:1:10 solution and HCl : H_2O_2 : H_2O = 1:1:20 solution in succession to etch a very thin GaAs layer, the goal of the step is removing metallic contaminants and forming a very thin oxidation layer on the GaAs wafer surface;NH_4OH : H_2O =1:5 solution is used as the removed oxide layers in the end. The effectiveness of the process is demonstrated by the operation of the GaAs wafer. Characterization of the oxide composition was carried out by X-ray photoelectron spectroscopy. Metal-contamination and surface morphology was observed by a total reflection X-ray fluorescence spectroscopy and atomic force microscope. The research results show that the cleaned surface is without contamination or metal contamination. Also, the GaAs substrates surface is very smooth for epitaxial growth using the rotary ultrasonic atomization technology.