Global optimization for power dispatch problems based on theory of moments

Non-convex of an optimal power dispatch problem makes it difficult to guarantee the global optimum. This paper presents a convex relaxation approach, called the Moment Semidefinite Programming (MSDP) method, to facilitate the search for deterministic global optimal solutions. The method employs a sequence of moments, which can linearize polynomial functions and construct positive semidefinite moment matrices, to form an SDP convex relaxation for power dispatch problems. In particular, the rank of the moment matrix is used as a sufficient condition to ensure the global optimality. The same condition can also be leveraged to estimate the number of global optimal solution(s). This method is effectively applied to {0,1}-economic dispatch (ED) problems and optimal power flow (OPF) problems. Simulation results showed that the MSDP method is capable of solving {0,1}-ED problems with integer values directly, and is able to identify if more than one global optimal solutions exist. In additional, the method can obtain rank-1 moment matrices for OPF’s counterexamples of existing SDP method, this ensures the global solution and overcomes the problem that existing SDP method cannot meet the rank-1 condition sometimes.     

An approach for minimizing a quadratically constrained fractional quadratic problem with application to the communications over wireless channels

Studies for the cognitive model are relatively new in the literature; however there is a growing interest in the communication field nowadays. This paper considers the cognitive model in the communication field as the problem of minimizing a fractional quadratic problem, subject to two or more quadratic constraints in complex field. Although both denominator and numerator in the fractional problem are convex, this problem is not so simple since the quotient of convex functions is not convex in most cases. We first change the fractional problem into a non-fractional one. Second, we consider the semi-definite programming (SDP) method. For the problem with m (m≤2) constraints, we use the SDP relaxation and obtain the exact optimal solution. However, for the problem with m (m>2) constraints, we choose the randomization method to gain an approximation solution in the complex case. At last, we apply this method to practical communications over wireless channels with good results.     

渭河干流关中段季节性水环境容量研究

针对季节性河流流量具有周期性变化的特点,采用季节性污水排放计划(SDP)的季节划分方法,提出季节性河流水环境容量计算方法。以渭河干流关中段为例,将一年划分为旱雨两季,利用一维水质模型计算8个季节划分方案和1个对照方案在50%、75%和90%保证率下的水环境容量。研究结果表明:在相同保证率下,分季节计算的渭河干流关中段COD和NH3-N环境容量分别是传统环境容量计算方法的1.17~1.59倍和1.25~1.79倍,表明分季节计算的河流水环境容量明显大于以年为单位计算的河流水环境容量。     

A note on semidefinite relaxation for 0-1 quadratic knapsack problems

We investigate in this note solution properties of semidefinite programming (SDP) relaxation for 0-1 quadratic knapsack problem (QKP). In particular, we focus on the issue of uniqueness of the optimal solution to the SDP relaxation for QKP. We first give a counterexample which shows that the optimal solution to the SDP relaxation for QKP could be non-unique. This is in contrast with the case of unconstrained 0-1 quadratic problems. A necessary and sufficient condition is then derived to ensure the uniqueness of the optimal solution to the SDP relaxation for QKP.     

移动Ad hoc网络服务发现协议

介绍移动Ad hoc网络的应用前景和主要研究内容,阐述服务协议的重要性以及服务发现协议中的基本概念,针对现有的移动Ad hoc网络服务发现协议的核心技术和设计思想进行分析,选取几种典型的服务发现协议进行对比,总结得出各类服务发现协议的优缺点和适用范围,并指出该领域的进一步研究方向。     

3D重构中的多项式约束模式*

针对基于单幅图像的3D重构因其约束条件的严重匮乏,而致使重构结果不确定的原因与机理进行了深入研究。以SFS重构方案为研究对象,提出首先将SFS问题规划为仅含二次约束的多项式系统,进而递次使用同伦分析法和精确线搜索技术,最后基于变量集构造一个SDP凸松弛。实验结果表明,这种重构方案不仅可以寻找所有全局解,优化迭代过程,加快收敛速度,而且可以避免产生不理想的局部解,彻底摆脱对初始假定的依赖,确保迭代过程收敛于一个全局极小值。借助多项式系统的完备解空间特性,大大提高了3D重构的精确度和唯一性,非常适用于非刚体表面重构。     

SDP-based approximation of stabilising solutions for periodic matrix Riccati differential equations

Numerically finding stabilising feedback control laws for linear systems of periodic differential equations is a nontrivial task with no known reliable solutions. The most successful method requires solving matrix differential Riccati equations with periodic coefficients. All previously proposed techniques for solving such equations involve numerical integration of unstable differential equations and consequently fail whenever the period is too large or the coefficients vary too much. Here, a new method for numerical computation of stabilising solutions for matrix differential Riccati equations with periodic coefficients is proposed. Our approach does not involve numerical solution of any differential equations. The approximation for a stabilising solution is found in the form of a trigonometric polynomial, matrix coefficients of which are found solving a specially constructed finite-dimensional semidefinite programming (SDP) problem. This problem is obtained using maximality property of the stabilising solution of the Riccati equation for the associated Riccati inequality and sampling technique. Our previously published numerical comparisons with other methods shows that for a class of problems only this technique provides a working solution. Asymptotic convergence of the computed approximations to the stabilising solution is proved below under the assumption that certain combinations of the key parameters are sufficiently large. Although the rate of convergence is not analysed, it appeared to be exponential in our numerical studies.     

事件驱动编程中对Browse的控制

从数据库管理系统设计中数据个性模块的顺序驱动和谐和事件驱动编程的比较入手,提出了事件驱编程中控制Browse需要考虑的几个问题,并具体分析了每个问题的解决办法。     

互联网上交互式视频技术与实现

介绍了在互联网上帝现交互式视频业务的关键技术和一个交互式视频点播与直播系统的实现。     

基于Linux的蓝牙系统核心协议栈的设计与实现

本文设计与实现的基于Linux平台的Bluetooth核心协议栈主要由四个模块组成：服务发现协议SDF模块，逻辑链路控制与适配协议L2CAP模块，串行线路模拟协议RFCOMM模块和主机控制接口HCI模块。在本核心协议栈的设计过程中，始终将提高整个协议栈的执行效率作为第一目标。为提高协议栈的效率，对协议栈进行了设计优化，采用了状态自动机、散列技术、缓冲机制、开放式平台、硬件模拟技术等一些先进技术。