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1.
研究了带无穷多个部件的,由一个可靠机器,一个不可靠机器与一个缓冲库构成的系统解的渐近性质.先讨论了对应于该系统的主算子的谱特征并且得到了在虚轴上除了0点外其它所有点都属于该主算子的豫解集,0是该主算子及其共轭算子几何重数为1的特征值.然后将该结果与作者以前的结果结合起来推出该系统的时间依赖解当时刻趋向于无穷时趋向于该系统的稳态解.  相似文献   

2.
本文研究一个可靠机器、一个不可靠机器与只容纳一个部件的缓冲库构成的系统的时间依赖解的渐近行为.首先在我们已有的工作基础上指出该模型的主算子生成的C_0-半群的本质增长界小于一个负数,由此推出0是该主算子的一级极点。然后用残数定理求该系统研究中出现的投影算子的表达式.最后证明该模型的时间依赖解指数收敛于其稳态解.本文的思想和方法适用于一个可靠机器、一个不可靠机器与容纳有限个部件的缓冲库构成的系统.  相似文献   

3.
研究由一个可靠机器,一个不可靠机器和一个缓冲库构成的生产线.首先对应于此系统的数学模型化为抽象Cauchy问题,然后运用C0-半群理论证明此模型存在唯一的非负解。  相似文献   

4.
研究一个可靠机器,一个具有无穷容量的缓冲库和一个不可靠机器构成的系统的主算子的谱.当机器1的加工率λ,机器2的加工率μ,部件从机器1成功地传送到机器2的概率η_1,机器2成功处理完部件的概率η_2满足一定的条件时,证明-μ不是该系统的主算子的特征值.  相似文献   

5.
研究带无穷多个部件的,由一个可靠机器,一个不可靠机器与一个缓冲库构成的系统主算子在左半复平面中的特征值,证明2√λη1μη2-λη1-μη2是该主算子的几何重数为1的一个特征值.  相似文献   

6.
本文用纯分析的方法给出了一个可靠机器 ,一个不可靠机器和一个缓冲库构成的系统解的存在唯一性证明  相似文献   

7.
研究由一个可靠机器,一个不可靠机器与一个无穷容量的缓冲库构成的系统主算子在左半复平面中的特征值,证明对一切θ∈(0,1),(2(λη_1μη_2)~(1/2)-λη_1-μη_2)θ都是该主算子的几何重数为1的一个特征值.  相似文献   

8.
本文对机器不可靠的二阀值控制存贮水平的生产存贮系统进行了研究,一旦机器发生故障,会立即得到修理以使它重新工作;对产品的需求假设是k个复合泊松到达过程的叠加,需求量为独立同分布的随机变量。我们得到了存贮水平稳态分布存在的充分条件、分布函数的显性表达式,以及在稳态下系统运行的一些性能指标。  相似文献   

9.
练肇通  邓永录 《应用数学》1996,9(3):278-282
本文讨论了由N个同型部件和一个服务设备组成的机器服务模型,在服务设备绝对可靠,或服务设备具有指数寿命,修理工对其修理的时间为PH分布,这两种情况下求得了系统的平稳概率分布,从而求得机器系统和服务设备的稳态可靠性指标,并证明了它们的首次失效时间均服从PH分布,服务设备和修理工的忙期亦服从PH分布.  相似文献   

10.
机器服务模型(又称机器修理模型或机器看管模型)是排队论所讨论的基本模型之一.在文献中所见到的机器服务模型中,都假定服务设备(或称修理设备)是不会失效的.可是在实践中,经常会碰到服务设备本身发生失效,不能为发生故障的机器服务.此时需要将失效的服务设备修好以后,服务设备才能继续为有故障的机器服务.这是一类更一般的机器服务模型,本文就研究这类模型.对服务设备可修的排队系统,被研究过的仅有M/G/1系统。在本文讨论的模型中,机器和服务设备都存在失效及修理.为避免混淆,对于机器,我  相似文献   

11.
Despite extensive studies on the flexibility of manufacturing systems over the last two decades, a unified measurement approach has not been developed. To this end, we integrate two domains of machine flexibility models from the literature: operational capability-based machine flexibility and time and cost-based machine flexibility, and propose a generic model to measure machine flexibility with consideration of uncertainties in the system. Furthermore, in our approach we include part characteristics such as processing time and processing cost, the number of operations that a machine can perform, and uncertainties in demand and machine-part assignment. The resulting framework to measure machine flexibility is a two-stage model: a super efficiency Data Envelopment Analysis Model and a flexibility model. The results show that the marginal system machine flexibility does not always increase as the number of operations that a machine can perform increases, and the system machine flexibility depends on the demand uncertainty.  相似文献   

12.
In this paper, we consider the problem of the optimal flow control for a production system with one machine which is subject to failures and produces one part type. In most previous work, it has been assumed that the machine has exponential up and down times, i.e., its state process is a Markov process. The system considered in our study has general machine up and down times. Our main result is establishing monotone properties for the optimal control policy.This work was partially supported by the National Science Foundation under Grants DDM-9215368 and EDI-9212122. The authors thank two anonymous reviewers for helpful comments and suggestions.  相似文献   

13.
锻压机床由于生产效率高和材料利用率高的特点,被广泛应用于各领域.然而,锻压机床发生故障时,其故障种类繁多、故障数据量大,所以对锻压机床故障源的快速、准确诊断较困难.针对该问题,文章提出一种将故障树分析法和混沌粒子群算法相融合的方法,对锻压机床的故障源进行故障诊断.该方法是先通过故障树分析法对锻压机床的故障进行分析从而得到故障模式及其故障概率,然后由得到的故障模式和已知的故障维修经验分析归纳出故障模式的学习样本,再根据得到的故障概率运用混沌粒子群算法的遍历性快速、准确地诊断出锻压机床发生故障的精确位置.文章提出的方法以锻压机床的伺服系统为例进行了故障诊断实验,将该实验结果与遗传算法、粒子群算法进行对比.实验结果表明,文章的算法在锻压机床伺服系统的故障诊断中准确度更高、速度更快.  相似文献   

14.
Rolling element bearings are the key components in many rotating machinery. For efficient performance of the machine it is necessary to accurately predict the effect of various parameters and operating conditions on the machine’s behavior. This paper deals with the development of a nonlinear model of the rotor-bearing system on rolling element bearings with clearance. Clearance is an important nonlinearity which can cause bifurcations and chaos as has been shown in this paper. In this paper a detailed model for clearance is developed. In this model the inner race center and the outer race center are not assumed to be collinear when relations for deflections in the rolling element are developed. The model is non-dimensionalized and then analyzed to reveal rich nonlinear phenomena. Further, for better performance of any machine it is necessary to identify and stay out of chaotic regimes of operation. Hence, Lyapunov exponents and Poincaré mappings are used to analyze the system and determine the regions of chaotic response.  相似文献   

15.
In this paper, a parallel implementation of Wang’s method for solving tridiagonal system of equations on the multiprocessor machine using occam language is presented. The parallel algorithm has been designed for shared and distributed memory machine that support data parallel and message passing. The over all performance of this implementation on 9 each of processors is given. The communication times are very important and any improvement on this communication would have a significant performance of the implementation. The significance of these results are discussed.  相似文献   

16.
This paper examines the transient and steady–state interference characteristics of a production system with one operator and n identical, semi–automatic and reliable machines. A stochastic model is developed to describe the system and analytical expressions for the percentage interference and mean output rate permachine with arbitrary distribution of concurrent time and exponential distribution of procssing time of each machine, have been obtained by using a state–space method and the regeneration point technique. A particular case is investigated and numerical results are presented illustrating some features of this machine inter ference problem  相似文献   

17.
Economic and economic-statistical design of a chi-square chart for CBM   总被引:1,自引:0,他引:1  
In this paper, the economic and economic-statistical design of a χ2 chart for a maintenance application is considered. The machine deterioration process is described by a three-state continuous time Markov chain. The machine state is unobservable, except for the failure state. To avoid costly failures, the system is monitored by a χ2 chart. The observation process stochastically related to the machine condition is assumed to be multivariate, normally distributed. When the chart signals, full inspection is performed to determine the actual machine condition. The system can be preventively replaced at a sampling epoch and must be replaced upon failure; preventive replacement costs less than failure replacement. The objective is to find the optimal control chart parameters that minimize the long-run average maintenance cost per unit time. For the economic-statistical design, an additional constraint guaranteeing the occurrence of the true alarm signal on the chart before failure with given probability is considered. For both designs, the objective function is derived using renewal theory.  相似文献   

18.
The problem of minimizing machine operation cost in a large-scale irrigated double-cropping rice production area in Malaysia was investigated. The combined effects of production environment, climatic conditions and agronomic requirements of the crop require the farmers to rent the machines from cooperatives or from the private sector. However, the high cost of operation and the unique machine demand structure lead to extreme machine shortages. Therefore, a production system which minimizes machine demand is required. In this study, a two-stage cost-minimizing procedure using dynamic programming and linear programming models was studied, and an example is presented.  相似文献   

19.
Live virtual machine migration can have a major impact on how a cloud system performs, as it consumes significant amount of network resources, such as bandwidth. A virtual machine migration occurs when a host becomes over-utilised or under-utilised. In this paper, we propose a network aware live migration strategy that monitors the current demand level of bandwidth when network congestion occurs and performs appropriate actions based on what it is experiencing. The Artificial Intelligence technique that is based on Reinforcement Learning acts as a decision support system, enabling an agent to learn an optimal time to schedule a virtual machine migration depending on the current bandwidth usage in a data centre. We show from our results that an autonomous agent can learn to utilise available network resources such as bandwidth when network saturation occurs at peak times.  相似文献   

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