Slice coherence in a query-based architecture for 3D heterogeneous printing

We report on 3D printing of artifacts with a structured, inhomogeneous interior. The interior is decomposed into cells defined by a 3D Voronoi diagram and their sites. When printing such objects, most slices the printer deposits are topologically the same and change only locally in the interior. The slicing algorithm capitalizes on this coherence and minimizes print head moves that do not deposit material. This approach has been implemented on a client/server architecture that computes the slices on the geometry side. The slices are printed by fused deposition, and are communicated upon demand.     

Multi-objective voltage and frequency regulation in autonomous microgrids using Pareto-based Big Bang-Big Crunch algorithm

Voltage and frequency regulation is one of the most vital issues in autonomous microgrids to ensure an acceptable electric power quality supply to customers. In this paper, a real-time control structure including power, voltage, and current control loops is proposed for microgrid inverters to restore voltage and frequency of the system after the initiation and load changes. The Proportional-Integral (PI) gains of the voltage controller are optimized in a real-time basis after a perturbation in the microgrid to have a fast and smooth response and a more stable system. The current controller produces Space Vector Pulse Width Modulation command signals to be fed into the three-leg inverter. The multi-objective optimization problem has objective functions of voltage overshoot/undershoot, rise time, settling time, and Integral Time Absolute Error (ITAE). The modified Multi-Objective Hybrid Big Bang-Bing Crunch (MOHBB-BC) algorithm is employed as one of efficient evolutionary algorithms in order to solve the optimization problem. The MOHBB-BC method obtains a set of Pareto optimal solutions; a fuzzy decision maker is used to pick up the most preferred Pareto solution as the final solution of the problem. Results from testing the control strategy on a case study are discussed and compared with previous works; according to them, the proposed method is able to obtain dynamic PI regulator gains to have a more appropriate response.     

基于NSGA-II算法的电容称重传感器抗偏载能力的优化

为了满足在保证电容称重传感器最小识别极距变化的同时达到提高其抗偏载能力的要求,对传感器进行了多目标优化的研究。分析计算了电容称重传感器力学性能与结构参数之间的关系,建立了以其导向性能和抗弯性能为优化目标的1/1000g精度电容称重传感器的多目标优化模型。应用Isight优化软件中的改进型非支配解遗传（NSGA-II）算法得到电容称重传感器的Pareto最优解集,并通过有限元验证了优化结果的准确性。研究表明,在保证电容称重传感器最小识别极距变化的前提下,极大地屏蔽了偏载对电容精度的影响,结果具有很强的实用性。     

求解多目标优化问题的新遗传算法

给出了求解多目标优化问题的一种新解法。定义了多目标优化问题的非劣方向,设计了方向杂交算子和简单的变异算子。标准算例的计算机仿真结果表明,新算法可以快速地找到一组范围广、分布均匀且数量充足的Pareto最优解。     

基于通用知识的软件设计安全性评估

安全性作为软件系统的重要属性,越来越受到人们的重视．在软件开发的早期对安全性进行评估,对软件的质量控制和成本控制有着重要意义．当前的软件安全性评估主要依靠专家评审,结果的客观性及准确性常常受到专家主观意见的影响．通过使用通用知识作为评估依据,提出一种可以对UML顺序图形式的软件设计文档进行自动化分析的方法,可以发现软件设计中潜在的安全性漏洞．该方法可以减少结果中的主观性,同时,通过基于该方法的辅助工具的使用,可以大大提高评估效率．     

Multi-directional blending for heterogeneous objects

This paper presents a novel multi-directional blending method for heterogeneous object design. Contrary to earlier studies, this paper introduces material blending through multiple features with different heterogeneous material composition. Feature-based method is used to represent and design heterogeneous objects with multi-directional material composition. The Voronoi diagram of multiple curves is constructed to generate bisector of the geometric domain. Then, metamorphosis from the bounding curve to multiple internal curves is performed using dynamic programming based optimization approach in two steps. First, optimum curve matching between internal curves and enclosing Voronoi cells is obtained. Then, an optimum ruling line alignment and insertion technique between the Voronoi diagram and the bounding curve is developed. Metamorphosis through complex concavities is also achieved. Finally, multi-directional material composition is mapped based on a set of relations.     

Interactive multiobjective fuzzy random programming through the level set-based probability model

This paper considers a multiobjective linear programming problem involving fuzzy random variable coefficients. A new fuzzy random programming model is proposed by extending the ideas of level set-based optimality and a stochastic programming model. The original problem involving fuzzy random variables is transformed into a deterministic equivalent problem through the proposed model. An interactive algorithm is provided to obtain a satisficing solution for a decision maker from among a set of newly defined Pareto optimal solutions. It is shown that an optimal solution of the problem to be solved iteratively in the interactive algorithm is analytically obtained by a combination of the bisection method and the simplex method.     

Convergence of multi-objective evolutionary algorithms to a uniformly distributed representation of the Pareto front

In evolutionary multi-objective optimization (EMO), the convergence to the Pareto set of a multi-objective optimization problem (MOP) and the diversity of the final approximation of the Pareto front are two important issues. In the existing definitions and analyses of convergence in multi-objective evolutionary algorithms (MOEAs), convergence with probability is easily obtained because diversity is not considered. However, diversity cannot be guaranteed. By combining the convergence with diversity, this paper presents a new definition for the finite representation of a Pareto set, the B-Pareto set, and a convergence metric for MOEAs. Based on a new archive-updating strategy, the convergence of one such MOEA to the B-Pareto sets of MOPs is proved. Numerical results show that the obtained B-Pareto front is uniformly distributed along the Pareto front when, according to the new definition of convergence, the algorithm is convergent.     

基于实时操作系统的嵌入式软PLC运行系统的研究和实现

在分析了几种常见软PLC控制方案后,提出了一种基于μC/OS-Ⅱ实时操作系统的软PLC运行系统的体系结构,给出了软PLC梯形图解释程序的实现过程,并且对运行系统的任务划分及任务间调度原理进行了分析研究.最后,基于ARM7嵌入式处理器实现了软PLC的基本功能.     

用VIS系统验证电路的实时特性的探讨

文章在分析形式化验证／综合系统VIS 的基础上,改进了该电子系统中的关键技术——二叉判定图（BDD）,使BDD能表示电路的定时性质,这样就为VIS系统能够进行电路的时间特性验证和实时模型检验打下了基础。