干扰约束下的认知无线电传输链路自适应算法

针对干扰约束下的认知无线电传输链路自适应算法开展研究,基于OFDM的认知用户与主用户共存,认知用户在保证对主用户干扰容限的前提下执行子载波与功率分配,以树形分支贪婪算法为基础,引入功率余量因子和干扰余量因子并通过比较余量因子相对大小来选择子载波,通过减小分支数以降低算法复杂度.仿真结果表明,改进的树形分支贪婪算法获得的...     

三维几何约束系统的等价性分析

针对过约束、完整约束和欠约束三维几何约束系统的求解问题,提出了等价性分析方法.该方法基于三维几何约束系统的内在等价性,充分挖掘几何领域知识,依据拆解约束闭环、缩减约束闭环和析出约束闭环等原则,采用等价约束替换来处理几何约束闭环问题,优化几何约束图的结构,实现几何约束系统的优化分解.最后用多个实例验证了该方法的正确性和有...     

软件体系结构动态演化的条件超图文法及分析

针对目前.软件体系结构动态演化描述方法的不足,提出用约束超图表示软件体系结构,用左右应用条件刻画软件体系结构动态演化的前断言和后断言,用条件超图文法建模软件体系结构动态演化过程.通过案例分析,讨论了如何构建条件超图文法并应用于软件体系结构动态演化.在此基础上,建立软件体系结构动态演化的一致性条件定义,给出动态演化的一致性判定方法.最后,设计实验进行分析,验证了方法的有效性.     

基于人机交互的炼钢连铸动态调度*

针对炼钢连铸动态调度问题,建立了问题的优化模型、设计了约束满足求解算法并分析了算法复杂度、开发了炼钢连铸动态调度的人机交互系统。当生产过程中的扰动事件发生时,系统能够通过人机交互并结合优化模型和多项式时间复杂度的算法获得可行且与原调度尽量一致的新调度方案,以确保动态调度前后整个生产过程的连续性和稳定性。     

一种基于改进径向基函数JSP算法

作为作业调度里面一类典型问题,Job-shop问题的求解是属于NP完全的,至今大规模Job-shop问题的有效算法仍未找到.在析取有向图模型基础上,通过减聚类方法构建径向基函数神经网络实现可互换工序对选取,利用最小均方算法对网络权重进行训练,以此为基础提出一种具备学习功能智能算法.数值仿真结果表明,所提算法对于大规模Job-shop问题求解存在较好效果,达到预期目的.     

非完整约束下的机器人运动规划算法

由非完整约束定义提出一种改进RRT(快速搜索随机树)算法,解决受动力学约束的移动机器人运动规划问题.该算法将移动机器人的非完整约束条件与RRT搜索算法相结合.针对RRT算法在全局状态空间均匀随机搜索导致算法无谓耗费代价大的缺陷,引入目标偏向思想,并选择计算复杂度低的距离参数提高求解速度.通过几类典型的非完整约束下的机器...     

多域环境下工作流访问控制时序策略组合研究

多域环境下工作流访问控制策略往往表现为异构策略的时序组合,其基本需求是使访问主体在一定的时间段或者时间周期内具有对客体的访问权限.XACML在描述策略组合时,并没有体现异构策略组合时态约束.根据GTRBAC提出的时态约束种类,定义了相关时态策略并进行了图解说明;并对XACML进行了扩展,引入了相应的时态约束元素.最后,...     

A new approach for the solution of singular optima in truss topology optimization with stress and local buckling constraints

The present paper investigates problems of truss topology optimization under local buckling constraints. A new approach for the solution of singular problems caused by stress and local buckling constraints is proposed. At first, a second order smooth-extended technique is used to make the disjoint feasible domains connect, then the so-called ε-relaxed method is applied to eliminate the singular optima from problem formulation. By means of this approach, the singular optimum of the original problem caused by stress and local buckling constraints can be searched approximately by employing the algorithms developed for sizing optimization problems with high accuracy. Therefore, the numerical problem resulting from stress and local buckling constraints can be solved in an elegant way. The applications of the proposed approach and its effectiveness are illustrated with several numerical examples. Received May 2, 2000     

On the implication problem for cardinality constraints and functional dependencies

In database design, integrity constraints are used to express database semantics. They specify the way by that the elements of a database are associated to each other. The implication problem asks whether a given set of constraints entails further constraints. In this paper, we study the finite implication problem for cardinality constraints. Our main result is a complete characterization of closed sets of cardinality constraints. Similar results are obtained for constraint sets containing cardinality constraints, but also key and functional dependencies. Moreover, we construct Armstrong databases for these constraint sets, which are of special interest for example-based deduction in database design.     

A Constraint-Based Approach for Deriving 3-D Structures of Cyclic Polypeptides

This paper presents an hybrid algorithm for deriving 3-D structures of cyclic polypeptides. The algorithm combines constraint-based techniques with the most widely used methods for non-cyclic polypeptides. The empirical results demonstrate that the proposed hybrid algorithm outperforms traditional methods especially with respect to running times.