A nested benders decomposition approach for telecommunication network planning

Despite its ability to result in more effective network plans, the telecommunication network planning problem with signal‐to‐interference ratio constraints gained less attention than the power‐based one because of its complexity. In this article, we provide an exact solution method for this class of problems that combines combinatorial Benders decomposition, classical Benders decomposition, and valid cuts in a nested way. Combinatorial Benders decomposition is first applied, leading to a binary master problem and a mixed integer subproblem. The subproblem is then decomposed using classical Benders decomposition. The algorithm is enhanced using valid cuts that are generated at the classical Benders subproblem and are added to the combinatorial Benders master problem. The valid cuts proved efficient in reducing the number of times the combinatorial Benders master problem is solved and in reducing the overall computational time. More than 120 instances of the W‐CDMA network planning problem ranging from 20 demand points and 10 base stations to 140 demand points and 30 base stations are solved to optimality. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

基于提升小波包的漏磁信号去噪研究

为了更好地解决对原始漏磁信号的噪声抑制问题,在讨论提升小波包变换的基本原理及特点的基础上,提出应用这种方法对漏磁信号进行分解和重构。与传统小波包变换相比较,该方法具有更高的分辨率和近似优化能力,研究结果表明,它能在保留原始漏磁信号有效成分的同时,更好地去除噪声。     

寿命周期费用分析中的数据采集问题探讨

寿命周期费用数据采集是寿命周期费用分析的关键问题之一。简要介绍了寿命周期费用的概念,探讨了寿命周期费用数据采集的目的与要求、费用数据的来源、内容、采集形式,以及对费用数据的处理等与寿命周期费用数据采集有关的问题。目的在于为寿命周期费用的数据采集提供一般性指导方法。     

基于高斯白噪声加入的EMD在旋转机械故障诊断中的应用研究

为了避免经验模式分解(EMD)过程中不同时间尺度函数间的模式混叠,采用基于高斯白噪声加入的经验模式分解方法,并将之应用于旋转机械故障诊断中。该方法主要是对同一信号重复若干次加入相互独立的高斯白噪声序列,并分别筛选固有模式函数,而后把各个对应的固有模式函数进行平均计算,消除白噪声对分解结果的影响。最后,通过对固有模式函数进行包络解调,从中提取故障特征。对实际旋转机械故障振动信号的分析结果表明,该方法能有效避免固有模式函数间模式混叠,提高故障诊断效果。     

一种新的基于特征值分解的双站无源定位算法

在自卫式噪声干扰的条件下,地面制导雷达将无法得到目标的斜距信息,无法实现对目标的定位,此时只有采用雷达组网方式,利用2个或多个雷达站的测角信息来对空间目标进行定位。提出一种基于特征值分解的新的定位跟踪算法,该算法具有计算简单、清晰,运算量小的优点,仿真也表明该算法有较好的精度。     

The effect of al particle size on thermal decomposition,mechanical strength and sensitivity of Al/ZrH2/PTFE composite

To study the thermal decomposition of Al/ZrH2/PTFE with different Al particle size as well as mechanical strength and impact sensitivity under medium and low strain rates, molding-vacuum sintering was adopted to prepare four groups of power materials and cylindrical specimens with different Al particle size. The active decomposition temperature of ZrH2 was obtained by TG-DSC, and the quasi-static me-chanics/reaction characteristics as well as the impact sensitivity of the specimen were studied respec-tively by quasi-static compression and drop-hammer test. The results show that the yield strength of the material decreased with the increase of the Al particle size, while the compressive strength, failure strain and toughness increased first and then decreased, which reached the maximum values of 116.61 MPa, 191％, and 119.9 MJ/m respectively when the Al particle size is 12—14μm because of particle size grading. The specimens with the highest strength and toughness formed circumferential open cracks and reacted partly when pressed. Those with developmental cracks formed inside did not react. It is considered that fracture of specimens first triggered initial reaction between Al and PTFE to release an amount of heat. Then ZrH2 was activated and decomposed, and participated in subsequent reaction to generate ZrC. The impact sensitivity of the specimens decreased with the increase of Al particle size.     

一种基于Q-R矩阵分解的自适应滤波算法

由于计算误差等因素的影响,致使滤波协方差阵不对称或负定,从而导致滤波器发散,影响滤波算法的收敛速度和稳定性。在机动加速度"当前"统计自适应卡尔曼滤波算法的基础上,引入了基于Q-R矩阵分解的自适应卡尔曼滤波算法。将协方差阵分解为两个矩阵的乘积,来保证协方差矩阵的正定性。仿真结果表明,该算法可以较好地跟踪机动目标,具有精度高、稳定好、收敛快等特点。     

给定任务和模式下指挥体系节点重要性评估方法

针对一般节点重要度评估方法没有考虑指挥体系网络与外界的交互以及自身运行机制的问题,研究了指挥节点的重要度评估方法,在一般网络结构重要度分析基础上,综合作战任务和指挥模式对节点的需求,提出了作战任务对节点依赖度以及指挥模式对节点依赖度的计算方法,最后设计了评估算法并给出具体算法流程,案例分析结果证明该算法合理、有效。     

舰艇编队海上运输补给物资需求预测方法

按照是否与任务、事件相关,将物资需求分为两类,对于任务、事件相关物资需求的预测,将任务进行合理的分解,并根据物资消耗与任务、事件之间的关系,给出了预测的一般模型;对于与任务、事件联系不紧密的物资需求的预测,则根据历史经验及该物资固有的消耗规律,提出了经验预测模型。为了解决舰艇编队海上运输补给物资需求预测所存在的问题,利用案例推理的方法生成了预测所需的样本数据,以最小二乘向量机(LSSVM)模型为预测模型,并以岛屿进攻作战的防空弹药需求预测为例进行了实例分析。结果表明:案例推理生成的样本数据可用,选用LSSVM模型的预测结果与其他预测模型表现出了一致性,但LSSVM相对误差较小;该方法在某种程度上解决了样本数据有限的问题,适用于作战物资需求的预测问题。     

Preparation of ammonium nitrate-based solid composite propellants supplemented with polyurethane/nitrocellulose blends binder and their thermal decomposition behavior

To improve the performance of solid composite propellants (SCPs) supplemented with ammonium nitrate (AN) as an oxidizer, the incorporation of energetic ingredients such as explosives, energetic binders or catalysts is a common effective approach. For this purpose, polyurethane (PU), a typical inert binder, was mixed with nitrocellulose (NC) as an energetic polymer. Numerous composite solid propellant compositions based on AN and NC-modified polyurethane binder with different NC ratios were prepared. The prepared formulations were characterized using Fourier transform infrared spectroscopy (FTIR), RAMAN spectroscopy, X-ray diffraction (XRD), electron densimetry, thermogravimetric (TG) analysis, and differential scanning calorimetry (DSC). A kinetic study was then performed using the iterative Kissinger-Akahira-Sunose (It-KAS), Flynn-Wall-Ozawa (It-FWO), and non-linear Vyazovkin integral with compensation effect (VYA/CE) methods. The theoretical performances, such as theoretical specific impulse, adiabatic flame temperature, and ideal exhaust gaseous species, were also determined using the NASA Lewis Code, Chemical Equilibrium with Application (CEA). Spectroscopic examinations revealed the existence of NC and full polymerization of PU in the prepared propellants. According to density tests, the density of the propellant increases as the nitrocellulose component increases. According to the thermal analysis and kinetics study, the increase in NC content catalyzed the thermal decomposition of the AN-based composite solid propellants. Based on the theoretical study, increasing the amount of NC in the propellant increased the specific impulse and, as a result, the overall performance.