PID在柴油发电机组输出稳定性控制中的应用研究

针对目前移动式柴油发电机组机械式调速器响应速度慢、精度差以及负载变化较大时发电机组输出电压和频率波动较大的问题,研究了PID在柴油发电机组稳定性控制中的应用,进行了电子调速器电路的研究与设计。对75kW柴油发电机组进行了空载、半载及满载实验,实验结果验证了设计电路和控制方法的正确性。该电子调速器采用PID方法对发动机转速进行控制,达到了改善柴油发电机组输出稳定性的目的,并且具有响应速度快和准确度高的特点。     

基于感知信息共享的C2网络特征分析

指挥控制（C2,Commandand Control）关系网络连接数的增加会增强指控节点之间的信息共享,但也会增加节点信息处理和交换负荷,如果达到一定程度,则会造成节点本身的“信息过载”从而影响C2网络性能。对此,通过研究C2网络在两种不同处理方式下的共享感知信息平均提交时间,用网络节点响应时间的均方差表征一个C2网络的共享态势感知时间的一致性,最后对两种不同结构C2网络特征参数的计算,说明了网络连接增加会导致信息提交时间的延长,但一致性会增强。     

数据挖掘在器材保障决策支持中的应用研究

针对器材保障现状,运用数据挖掘技术,探索器材保障决策支持问题.设计了器材保障决策支持系统中数据挖掘应用的解决方案,该方案包括了项目规划和应用设计,并以器材平时消耗预测为例,运用多元回归模型算,法进行了挖掘实现.数据挖掘为保障决策提供了更加丰富和科学的信息,可以较好地满足器材保障决策支持的需要.     

模糊灰色关联模型在遮弹层防护性能评价中的应用

为对遮弹层防护性能进行综合评价,建立了遮弹层防护性能评价指标体系,采用多对象模糊综合评价和加权多层次灰色关联评价相结合的方法.得到了遮弹层防护性能的二级模糊灰色关联评价模型,并对五种遮弹层的防护性能进行了评估.结果表明,综合考虑直接成本、施工条件、伪装性能等因素,刚玉块石混凝土遮弹层防护性能最佳.该模型为遮弹层防护能力综合评估提供了理论依据.     

The effects of model parameter deviations on the variance of a linearly filtered time series

We consider a general linear filtering operation on an autoregressive moving average (ARMA) time series. The variance of the filter output, which is an important quantity in many applications, is not known with certainty because it depends on the true ARMA parameters. We derive an expression for the sensitivity (i.e., the partial derivative) of the output variance with respect to deviations in the model parameters. The results provide insight into the robustness of many common statistical methods that are based on linear filtering and also yield approximate confidence intervals for the output variance. We discuss applications to time series forecasting, statistical process control, and automatic feedback control of industrial processes. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

Nonperiodic preventive maintenance for repairable systems

As a complex system with multiple components usually deteriorates with age, preventive maintenance (PM) is often performed to keep the system functioning in a good state to prolong its effective age. In this study, a nonhomogeneous Poisson process with a power law failure intensity is used to describe the deterioration of a repairable system, and the optimal nonperiodic PM schedule can be determined to minimize the expected total cost per unit time. However, since the determination of such optimal PM policies may involve numerous uncertainties, which typically make the analyses difficult to perform because of the scarcity of data, a Bayesian decision model, which utilizes all available information effectively, is also proposed for determining the optimal PM strategies. A numerical example with a real failure data set is used to illustrate the effectiveness of the proposed approach. The results show that the optimal schedules derived by Bayesian approach are relatively more conservative than that for non‐Bayesian approach because of the uncertainty of the intensity function, and if the intensity function are updated using the collected data set, which indicates more severe deterioration than the prior belief, replacing the entire system instead of frequent PM activities before serious deterioration is suggested. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

Robustness of efficient server assignment policies to service time distributions in finite‐buffered lines

We study the assignment of flexible servers to stations in tandem lines with service times that are not necessarily exponentially distributed. Our goal is to achieve optimal or near‐optimal throughput. For systems with infinite buffers, it is already known that the effective assignment of flexible servers is robust to the service time distributions. We provide analytical results for small systems and numerical results for larger systems that support the same conclusion for tandem lines with finite buffers. In the process, we propose server assignment heuristics that perform well for systems with different service time distributions. Our research suggests that policies known to be optimal or near‐optimal for Markovian systems are also likely to be effective when used to assign servers to tasks in non‐Markovian systems. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

基于条件熵的不完备信息系统属性约简算法

在相容关系下定义了三种不完备条件熵——H′条件熵、E′条件熵和I′条件熵,并对它们的性质进行了分析比较,研究发现,H′条件熵和I′条件熵不适用于相容关系下信息观点的约简。利用E′条件熵刻画信息系统中属性的相对重要性,设计了一种新的基于信息论观点的启发式约简算法,它统一了完备信息系统与非完备信息系统中的约简方法。通过实例说明,该算法能得到决策表的相对约简。     

地理信息系统专业实践教学体系研究

实践教学是GIS专业教学至关重要的环节。结合GIS知识体系结构、专业特点和社会需求,讨论了GIS专业实践教学体系的基本框架及其依托。     

新疆生产建设兵团哈汉民族关系解读

新疆生产建设兵团在促进边疆社会发展和维护稳定方面发挥了十分重要的作用。兵团和谐的民族关系是兵团进一步发挥屯垦戍边历史作用的保证,通过对农八师哈萨克族与汉族杂居区的民族关系现状和传统风俗习惯的变迁对民族关系的影响的解读,进而进行经济学角度的分析,有利于我们把握兵团民族关系发展的规律。