The building evacuation problem with shared information

In this article, the Building Evacuation Problem with Shared Information (BEPSI) is formulated as a mixed integer linear program, where the objective is to determine the set of routes along which to send evacuees (supply) from multiple locations throughout a building (sources) to the exits (sinks) such that the total time until all evacuees reach the exits is minimized. The formulation explicitly incorporates the constraints of shared information in providing online instructions to evacuees, ensuring that evacuees departing from an intermediate or source location at a mutual point in time receive common instructions. Arc travel time and capacity, as well as supply at the nodes, are permitted to vary with time and capacity is assumed to be recaptured over time. The BEPSI is shown to be NP‐hard. An exact technique based on Benders decomposition is proposed for its solution. Computational results from numerical experiments on a real‐world network representing a four‐story building are given. Results of experiments employing Benders cuts generated in solving a given problem instance as initial cuts in addressing an updated problem instance are also provided. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Estimating failure time distribution and its parameters based on intermediate data from a Wiener degradation model

Instead of measuring a Wiener degradation or performance process at predetermined time points to track degradation or performance of a product for estimating its lifetime, we propose to obtain the first‐passage times of the process over certain nonfailure thresholds. Based on only these intermediate data, we obtain the uniformly minimum variance unbiased estimator and uniformly most accurate confidence interval for the mean lifetime. For estimating the lifetime distribution function, we propose a modified maximum likelihood estimator and a new estimator and prove that, by increasing the sample size of the intermediate data, these estimators and the above‐mentioned estimator of the mean lifetime can achieve the same levels of accuracy as the estimators assuming one has failure times. Thus, our method of using only intermediate data is useful for highly reliable products when their failure times are difficult to obtain. Furthermore, we show that the proposed new estimator of the lifetime distribution function is more accurate than the standard and modified maximum likelihood estimators. We also obtain approximate confidence intervals for the lifetime distribution function and its percentiles. Finally, we use light‐emitting diodes as an example to illustrate our method and demonstrate how to validate the Wiener assumption during the testing. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

海洋环境中基于WVD的LFM信号检测方法

海洋环境中弱信号的谱与海杂波的谱相混叠 ,目标和背景的位置差异很小 ,经典的频域或空域处理对海杂波中弱信号的检测难以奏效。鉴于Wigner-Ville分布 (WVD)对线性调频信号 (LFM )具有时频聚集性这一特点 ,提出了一种海洋环境中基于WVD的LFM信号检测方法。利用雷达采集的真实海杂波数据 ,在不同信杂比的条件下 ,研究了该方法与经典频域法在信号检测中的差别。通过实验分析 ,与经典方法相比 ,该方法具有明显的优越性 ,且信杂比达到 -14 . 3dB时 ,其仍能很好地对信号进行检测。     

内置频率对Duffing振子微弱二进制相移键控信号盲检测影响

采用Duffing振子实现对微弱二进制相移键控（Binary Phase Shift Keying, BPSK）信号的盲检测时，Duffing系统输出的周期态和混沌态转换之间存在过渡带。针对这一问题，推导出过渡带时长和Duffing系统内置频率之间的关系表达式；指出内置频率越高，过渡带时间越短；仿真实验给出时间频率响应曲线。内置频率的提高，会降低系统检测微弱信号的灵敏度。针对这一问题，推导出周期态下Duffing系统输出幅度作为因变量、内置频率作为自变量的表达式；仿真实验给出幅频响应曲线。针对微弱BPSK信号盲检测，建立变尺度方法和检测阵列相结合的基于S变换提取Duffing系统输出幅度包络的微弱BPSK信号盲检测模型，仿真实验验证了模型方法的有效性。     

一类非线性控制系统模型的数学分析

采用非线性分析的方法,研究了一类非线性控制系统模型,得到解的整体存在性。     

使用双水压传感器抗风浪干扰原理

提出了在水雷上使用双水压传感器的设想.传统水雷只使用一个水压传感器,提供的信号信息稍嫌不足,给水压引信抗风浪干扰带来了限制.通过使用两个传感器,利用海浪水压场传播时在两个传感器上的时延信息,使用抵消方法压制海浪水压信号.初步分析表明,使用双传感器可以使水压引信抵抗一定的海浪水压信号的干扰.     

质漏对联合循环化学发动机性能的影响

分析存在有限速率传质和质漏损失的联合循环化学发动机性能,导出功率、效率最佳关系,最大功率及其相应效率,以及最大效率及其相应功率     

防空兵武器装备发展论证专家系统的开发

首先阐明了防空兵武器装备发展论证专家系统开发的目标任务和建造原则,然后建立了专家系统的一般结构,并论述了系统开发过程中的问题定义与系统分析、知识获取、知识表示、软件实现、系统测试与评价等各个环节所应完成的任务,指出了在专家系统开发过程中潜在的主要问题。对于建立一个完备的、权威的防空兵武器装备发展论证专家系统有一定的指导意义。     

多目标攻击导弹捷联惯导的传递对准

在分析中距复合制导空空导弹捷联惯导传递对准的基础上,提出由机载火控系统根据导弹发射包线计算发出开始捷联惯导传递对准精对准的时刻,导弹惯导提前进行传递精对准的方法。利用此方法可以解决机载武器系统多目标攻击空空导弹传递对准满足连续发射多枚导弹实时性要求的问题。最后,在单目标情况下就开始传递对准时刻包线给出了算例。     

可供实用的舰船风浪中摇荡时历预报的模式

舰船在风浪中摇荡时历的极短期预报 ,具有多方面的实用价值 .现有的各种预报方法中 ,以卷积法和时间序列法中的ARMA模型较为常用 ,但如何测量艏前波是上述方法实施的前提条件 ,则未能解决 .文中提出的在舰船舯部装塔克测波仪 ,将所测波形时历转换为艏前任意点波形时历的方法 ,可解决上述矛盾 .再采用ARMA建模、依AIC法则估计模型阶数的预报方式 ,即可用于实船进行摇荡时历短期预报