基于加权HMM的车辆电源系统状态预测

针对车辆电源系统状态趋势问题,提出了一种加权隐马尔可夫模型的状态预测方法。通过建立电源系统的隐马尔可夫模型,利用加权预测思想对隐马尔可夫模型中隐状态序列进行预测,将最大概率隐状态利用观测概率密度计算出状态观测值。通过对电压调节脉宽信号的导通率进行预测,并与BP神经网络和自回归（AR）模型对相同序列的预测结果进行对比,结果表明该方法对系统的状态变化具有较好的预测能力。     

HMM隐状态的粒子滤波估计

利用隐马氏模型解决实际问题时,其最终目的往往是隐状态估计问题。传统的Viterbi算法适用范围有限,而粒子滤波通过一组加权样本逼近状态的最优估计,适用于任意非线性、非高斯动态系统状态估计问题。利用粒子滤波的优点,提出了基于SISR的HMM隐状态估计算法,仿真结果表明,该方法比Viterbi算法有更高的估计精度。     

基于隐马尔可夫模型的软件状态评估预测方法

随着软件系统功能和性能的强化和提高,企业的管理效率在不断提升,运营模式也越来越丰富.与此同时,软件系统变得越来越复杂,这向软件系统管理和维护提出了严峻的挑战.如何通过采集系统外部特征参数,对系统内部状态进行客观、准确地评估和预测,成为亟待解决的问题.为此,提出了一种基于隐马尔可夫模型的软件系统状态评估预测方法.该方法基于软件系统外在特征参数,通过K-means方法构建系统的观测状态,并以此建立隐马尔可夫模型,建立起系统外在状态（观测状态）和内部状态（隐藏状态）之间的联系;再利用三次指数平滑法对具有周期性变化的系统特征参数进行预测,即可预测系统未来状态.针对基于B/S软件架构的信息管理系统的实验,其结果表明该方法对系统状态评估和预测具有较高的准确性.     

基于操作语义的磁臂隐通道分析*

深入分析磁臂隐通道的产生及产生的原因,发现目前基于系统顶级描述和基于系统源代码搜索方法难以找出这类隐通道,提出一种基于操作语义的方法来研究磁臂隐通道,将磁臂调度过程中的进程看做一个抽象机,以Plotkin的结构化操作语义给出电梯调度算法的推导规则;根据推导规则得到进程抽象机所有状态以及进程抽象机状态的动态变化历史,这样就构成完整的信息传导操作语义模型.研究与分析两个高低安全级进程抽象机状态变迁及状态变迁序列,从而找到其中存在的磁臂隐通道.     

人工心理情感模型的个人机器人

以心理动力学中心理能量概念为基础,根据情感能量守恒定律,建立了情感状态能量分布描述空间和情感状态的概率描述空间,分析情绪状态的变化过程,提出情绪状态自发转移过程的隐马尔可夫链及其模型算法.利用MATLAB建立相关情感状态变化的仿真研究平台,研究情感状态的变化规律.根据以上人工心理情感模型及其变化规律构建出个人机器人综合研究平台软、硬件体系结构,并通过该系统的实际运行实验验证了其有效性.     

网络风险评估方法研究

为了进行网络风险评估,采用隐马尔可夫随机过程作为分析手段,以入侵检测系统的输出（报警事件）为处理对象,建立了描述主机系统受到攻击后状态转化的隐马尔可夫模型(HMM),给出了主机系统风险指数的计算方法,并经过简单叠加得到整个网络风险的定量评价。最后通过实验证实了所提出方法的有效性。     

基于HMM的蒙古语语音合成技术研究

基于隐马尔科夫模型的语音合成方法是当今语音合成的主流方法,它已被广泛应用于英语、汉语、日语等语音合成系统中。然而基于隐马尔科夫模型的蒙古语的语音合成技术研究还处于空白状态。首次将基于隐马尔科夫模型的语音合成方法用于蒙古语语音合成,并进行了语音合成实验。从最终合成系统的效果来看,合成的语音整体稳定流畅,可懂度高,而且节奏感比较强,主观平均得分为3.80。这为进一步研究基于隐马尔科夫模型的蒙古语语音合成技术奠定了基础。     

知识化制造系统中动态调度的自适应策略研究

针对知识化制造系统中的动态调度问题，结合知识化制造单元的高智能特征，提出了B-Q学习算法．并基于该算法构建了一种自适应调度控制策略．针对知识化制造系统运行过程中系统状态空间较大的特点，通过提取系统状态特征，对系统状态进行合理聚类，有效地降低了系统状态空间的复杂性．根据系统当前所处的瞬时状态．选取不同的调度规则对缓冲区中工件进行有效调度．仿真结果验证了所提出调度控制策略的有效性．     

航空发动机的健康指标构建与剩余寿命预测

预测与健康管理技术能够有效的评估系统健康状态、预测系统剩余使用寿命,是提高复杂系统安全性、经济性的重要保障.为全面评估系统健康状态,本文提出了一种基于深度置信网络(DBN)的无监督健康指标构建方法,并结合隐马尔可夫模型(HMM)进行系统剩余寿命预测.首先,通过无监督训练深度置信网络实现历史数据的特征提取,进而构建健康指标;其次,利用健康指标集训练隐马尔可夫模型,实现设备健康状态的自动识别;最后,通过DBN-HMM混合模型来计算系统剩余寿命.采用商用模块化航空推进系统仿真软件(C-MAPSS)给出的航空发动机数据集,验证了上述方法的有效性.     

基于状态持续时间的HMM语音识别模型

针对经典隐马尔可夫模型对状态持续时间的函数表达与实际语音的物理事实不相符合这一缺点,在通常隐马尔可夫的基础上引入状态持续时间参数,建立基于状态持续时间的HMM语音识别模型（SDHMM）,并用其进行语音识别实验,与经典隐马尔可夫模型相比,识别率有所提高。     

Synthesis of deadlock prevention policy using Petri nets reachability graph technique

This paper proposes a subclass of generalized stochastic Petri net (GSPN) model, called TS³PR, which is modified the systems of simple sequential processes with resources (S³PR) with timed information. Based on the subclass of GSPN, a new deadlock prevention policy is developed by using reachability graph technique. The foundation of the new control policy is to manipulate all the dead states of the system nets. This study is able to change dead states into vanishing ones by additional immediate transitions. A live TS³PR model can then be obtained. It is worthwhile to notice that this study is different from adding additional control place policies in previous literature. Experimental results, indicate that our new control policy is with maximally permissive markings than conventional place‐control ones. As a result, we can infer that our proposed control policy seems to be used in Petri nets deadlocked systems. To our knowledge, this is the first work that employs the additional transitions to obtain the deadlock prevention policy. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Generalized stochastic Petri nets: a definition at the net leveland its implications

The class of Petri nets obtained by eliminating timing from generalized stochastic Petri net (GSPN) models while preserving the qualitative behavior is identified. Structural results for those nets are derived, obtaining the first structural analysis of Petri nets with priority and inhibitor arcs. A revision of the GSPN definition based on the structural properties of the models is presented. It is shown that for a (wide) class of nets, the definition of firing probabilities of conflicting immediate transitions does not require the information on reachable markings. Identification of the class of models for which the net-level specification is possible is also based on the structural analysis results. The procedure for the model specification is illustrated by means of an example. It is also shown that a net-level specification of the model associated with efficient structural analysis techniques can have a substantial impact on model analysis     

Time scale decomposition of a class of generalized stochastic Petrinet models

A time-scale decomposition (TSD) algorithm of a class of generalized stochastic Petri net (GSPN) models of systems comprising activities whose duration differ by orders of magnitude is presented. The GSPN model of a system can be decomposed into a hierarchical sequence of aggregated subnets, each of which is valid at a certain time scale. These smaller subnets are solved in isolation and their solutions are combined to get the solution of the whole system. A degradable multiprocessor system which would be intractable using conventional techniques, is analyzed using TSD. The complexity of the TSD algorithm can be orders of magnitude smaller without any significant loss in the accuracy of the result. In general, the error due to aggregation is proportional to the maximum degree of coupling between aggregates. An expression of the error due to aggregation is also given in terms of the ratio of fast and slow transitions in the GSPN model. The algorithm is easy to use and can be easily automated     

基于广义随机Petri网的CIMS多任务可靠性研究

CIMS生产的复杂性要求其可靠性模型可以精确地反映生产过程,由于传统的可靠性建模方法无法兼顾CIMS的时间动态特性,所以针对一个复杂的有多个加工任务的CIMS制造单元,由于其机器加工工件的时间均为指数分布,则采用广义随机Petri网进行多任务可靠性建模,在此基础上基于Petri网行为表达式,将矩母函数思想引入其中,不必生成可达标识图就可通过计算模型的传递函数,进而得到整个系统的多任务可靠度,该可靠性指标可以更直观地反映具有多种加工任务的整个CIMS的运行性能。     

基于GSPN的工作流模型性能评价方法与应用

广义随机Petri网因其具有坚实的理论基础、强大的分析功能和易于表达的图形化方式,在工作流模型性能评价领域应用越来越广泛。论文着重讨论了基于广义随机Petri网的工作流模型性能评价的技术和方法,对于其分析过程中涉及的问题,尤其是广义随机Petri网的等价化简问题,进行了详细的阐述。文章最后结合一个应用实例“全国高等教育网上阅卷系统”对建模和分析评价过程进行了说明。     

从UML到GSPN的转换和性能分析方法

UML模型一般不能直接进行性能分析,需要利用模型转换的方法将其转换成其他分析模型,比如排队论、随机进程代数或者随机Petri网等模型。利用Eclipse平台上的Papyrus建立3种类型的UML模型(用例图、部署图和活动图)来对系统进行建模,并利用MARTE规范添加一些性能相关的信息;然后利用ATL实现UML模型到广义随机Petri网(GSPN)模型的转换,并使用XStream将上一步得到的GSPN模型转换成分析工具所支持的格式;最后利用基于GSPN的性能分析方法进行系统性能分析。同时给出了一系列性能指标的计算方法,如利用率、吞吐量、平均等待请求的数目以及响应时间等,可以考察系统性能的多个方面,方便系统设计和开发人员对系统性能进行分析和优化。     

基于GSPN的网络系统动态可靠性建模方法

针对传统可靠性建模方法难以描述和评价网络系统动态可靠性这一难题,提出一种基于广义随机Petri网(generalized sto-chastic petri net,GSPN)的网络系统动态可靠性建模方法,在讨论GSPN的形式化定义和建立GSPN建模要素与可靠性模型参数之间对应关系的基础上,详细描述了网络系统动态可靠性建模的过程;最后以某型车电系统为例,通过仿真实验得到了系统可用度指标的动态变化曲线,验证了所提方法的有效性。     

A combined queueing network and stochastic Petri-net approach for evaluating the performability of fault-tolerant computer systems

In this paper the performability analysis of fault-tolerant computer systems using a hierarchical decomposition technique is presented. A special class of queueing network (QN) models, the so-called BCMP [4], and generalized stochastic Petri nets (GSPN) [1] which are often used to separately model performance and reliability respectively, have been combined in order to preserve the best modelling features of both.

A conceptual model is decomposed into GSPN and BCMP submodels, which are solved in isolation. Then, the remaining GSPN portion of the model is aggregated with flow-equivalents of BCMP models, in order to compute performability measures. The substitutes of BCMP models are presented by means of simple GSPN constructs, thereby preserving the 1st and 2nd moments of the throughput. A simple example of a data communication system where failed transmissions are corrected, is presented.     

Marking Optimization of Weighted Marked Graphs

Cyclic manufacturing systems can be modeled by marked graphs, which are an elementary class of Petri nets. To model systems with bulk services and arrivals and to reduce the size of the model, weighted marked graphs can be used. An important step when designing these systems is the definition of the number of manufacturing resources to be used in order to reach a given productivity. In terms of timed Petri nets, this is known as the marking optimization problem and consists of reaching a given average cycle time while minimizing a linear combination of markings. In this paper, a necessary and sufficient condition to obtain a feasible solution of the marking optimization problem of weighted marked graphs with deterministic times is established. A fast heuristic solution, based on an iterative process and using simulation, is given. An example and an application to manufacturing systems are presented.     

多通道压力测试系统Petri网建模及其性能分析

建立了n路多通道压力测试系统的广义随机Petri网(GSPN)模型,利用模型的可达图和MC链分析了GSPN模型的基本性能;推导出了压力测试系统的测试性能的数学公式,测试性能包括各部分的利用率、单位时间内的激发次数、系统时间延迟;并且分析了测试系统各部分之间的相互影响。经过实验验证,证明了该模型的正确性。