战车火炮姿态测量系统原位标定技术和方案设计

为了降低姿态测量系统的启动漂移和标定误差,提高测量和导航精度,针对系统安装特色,提出了一种原位快速标定方案。分析了系统可观测性,利用等效陀螺信息推导了多位置原位标定方案;研究了最优标定和次优标定问题,分析了标定精度和坡度之间的关系;设计了一种针对系统安装特色的多位置编排方案,完成了大坡度范围下的原位标定。仿真结果表明:方案要求简单,应用范围广,能够完成大坡度范围下高精度快速标定,具有重要的工程应用价值。     

Optimal replacement of continuously degrading systems in partially observed environments

Motivated by wind energy applications, we consider the problem of optimally replacing a stochastically degrading component that resides and operates in a partially observable environment. The component's rate of degradation is modulated by the stochastic environment process, and the component fails when it is accumulated degradation first reaches a fixed threshold. Assuming periodic inspection of the component, the objective is to minimize the long‐run average cost per unit time of performing preventive and reactive replacements for two distinct cases. The first case examines instantaneous replacements and fixed costs, while the second considers time‐consuming replacements and revenue losses accrued during periods of unavailability. Formulated and solved are mixed state space, partially observable Markov decision process models, both of which reveal the optimality of environment‐dependent threshold policies with respect to the component's cumulative degradation level. Additionally, it is shown that for each degradation value, a threshold policy with respect to the environment belief state is optimal if the environment alternates between two states. The threshold policies are illustrated by way of numerical examples using both synthetic and real wind turbine data. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 395–415, 2015     

基于混料设计的快硬土壤固化材料配方优化

为探索普通硅酸盐水泥(P·O)、熟石灰(HL)、硅灰(SF)三元混料系统对固化土无侧限抗压强度的影响,综合极端顶点设计和均匀设计思想建立混料回归模型,得出了响应面图形,确定了三元混料系统的最佳配方。在该配方下,固化土7d实际抗压强度可以达到4.75MPa。通过交互作用分析揭示了混料因子间的作用规律:P·O与HL交互作用对固化土7d无侧限抗压强度影响极其显著,P·O与SF交互作用对固化土7d无侧限抗压强度影响显著。对比试验表明,该混料设计方案对提高固化土7d无侧限抗压强度有显著效果,对土壤固化剂配合比优化设计和固化土无侧限抗压强度预测具有指导意义。     

某型导弹检测仪快速检校研究

针对某型导弹检测仪采用手动检测与校正致使校验仪器多、操作复杂、效率低等问题,分析了该导弹检测仪需检校的参数和硬件资源,提出了导弹检测仪快速检校系统总体方案,开发了基于C8051F040单片机的导弹检测仪快速检校系统,研究了导弹检测仪快速检校的方法。该快速检校系统能够提高导弹检测仪检校的速度和效率,对提高该装备的快速保障能力具有重要意义。     

基于NSGA-II和多属性决策的防空火力分配

为了解决防空火力分配问题,首先运用NSGA-II算法求出Pareto最优解集,然后运用多属性决策方法对Pareto最优解集中的解进行综合评估,并从中找出一个最优解。用区间数定性描述各属性,建立了防空火力分配的三目标优化模型。描述了NSGA-II算法和多属性决策方法的运算步骤。在仿真算例中,得到了一个最佳防空火力分配方案,说明该方法对于防空火力分配问题有良好的应用价值。     

被动全向声纳浮标跟踪潜艇的优化布放方法

反潜飞机利用被动全向声纳浮标可以隐蔽地跟踪潜艇,但浮标消耗量大。在满足定位精度的条件下,如何优化布放浮标以便有效增加跟踪时间是一个亟待解决的问题。首先分析了浮标探测性能和浮标群相对位置对定位精度的影响,得到浮标布放的五种基本原则;然后结合水下目标跟踪技术提出了两种用被动全向声纳浮标跟踪潜艇的优化布放方法:一种是利用遗传算法来优化每一枚浮标的布放位置,另一种是将一批次投放2-4枚浮标的多维优化问题简单转换成一维优化问题来确定浮标的布放位置。最后仿真计算了这两种方法的跟踪性能及浮标消耗量。仿真结果表明,两种优化布放方法均能满足跟踪要求,前者的浮标消耗量比后者略少,但后者的投放批次少很多,有利于减少人员的工作量。     

舰艇编队对空防御队形优化配置模型

分析了海上机动编队中防空舰的位置配置对舰艇编队拦截目标效果的影响,通过舰艇对来袭目标拦截概率的推导,建立了被掩护舰的生存概率模型,从而提供了一种解算编队防御队形最佳配置的方法。     

Signal‐to‐interference‐plus‐noise ratio estimation for wireless communication systems: Methods and analysis

The Signal‐to‐Interference‐plus‐Noise Ratio (SINR) is an important metric of wireless communication link quality. SINR estimates have several important applications. These include optimizing the transmit power level for a target quality of service, assisting with handoff decisions and dynamically adapting the data rate for wireless Internet applications. Accurate SINR estimation provides for both a more efficient system and a higher user‐perceived quality of service. In this paper, we develop new SINR estimators and compare their mean squared error (MSE) performance. We show that our new estimators dominate estimators that have previously appeared in the literature with respect to MSE. The sequence of transmitted bits in wireless communication systems consists of both pilot bits (which are known both to the transmitter and receiver) and user bits (which are known only by the transmitter). The SINR estimators we consider alternatively depend exclusively on pilot bits, exclusively on user bits, or simultaneously use both pilot and user bits. In addition, we consider estimators that utilize smoothing and feedback mechanisms. Smoothed estimators are motivated by the fact that the interference component of the SINR changes relatively slowly with time, typically with the addition or departure of a user to the system. Feedback estimators are motivated by the fact that receivers typically decode bits correctly with a very high probability, and therefore user bits can be thought of as quasipilot bits. For each estimator discussed, we derive an exact or approximate formula for its MSE. Satterthwaite approximations, noncentral F distributions (singly and doubly) and distribution theory of quadratic forms are the key statistical tools used in developing the MSE formulas. In the case of approximate MSE formulas, we validate their accuracy using simulation techniques. The approximate MSE formulas, of interest in their own right for comparing the quality of the estimators, are also used for optimally combining estimators. In particular, we derive optimal weights for linearly combining an estimator based on pilot bits with an estimator based on user bits. The optimal weights depend on the MSE of the two estimators being combined, and thus the accurate approximate MSE formulas can conveniently be used. The optimal weights also depend on the unknown SINR, and therefore need to be estimated in order to construct a useable combined estimator. The impact on the MSE of the combined estimator due to estimating the weights is examined. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004     

Bounding the optimal burn‐in time for a system with two types of failure

Burn‐in is a widely used method to improve the quality of products or systems after they have been produced. In this paper, we consider the problem of determining bounds to the optimal burn‐in time and optimal replacement policy maximizing the steady state availability of a repairable system. It is assumed that two types of system failures may occur: One is Type I failure (minor failure), which can be removed by a minimal repair, and the other is Type II failure (catastrophic failure), which can be removed only by a complete repair. Assuming that the underlying lifetime distribution of the system has a bathtub‐shaped failure rate function, upper and lower bounds for the optimal burn‐in time are provided. Furthermore, some other applications of optimal burn‐in are also considered. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004     

Resource allocation in an asymmetric technology race with temporary advantages

We consider two opponents that compete in developing asymmetric technologies where each party's technology is aimed at damaging (or neutralizing) the other's technology. The situation we consider is different than the classical problem of commercial R&D races in two ways: First, while in commercial R&D races the competitors compete over the control of market share, in our case the competition is about the effectiveness of technologies with respect to certain capabilities. Second, in contrast with the “winner‐takes‐all” assumption that characterizes much of the literature on this field in the commercial world, we assume that the party that wins the race gains a temporary advantage that expires when the other party develops a superior technology. We formulate a variety of models that apply to a one‐sided situation, where one of the two parties has to determine how much to invest in developing a technology to counter another technology employed by the other party. The decision problems are expressed as (convex) nonlinear optimization problems. We present an application that provides some operational insights regarding optimal resource allocation. We also consider a two‐sided situation and develop a Nash equilibrium solution that sets investment values, so that both parties have no incentive to change their investments. © 2012 Wiley Periodicals, Inc. Naval Research Logistics 59: 128–145, 2012