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Liveness enforcing supervision for resource allocation systems with process synchronizations and unreliable resources.

机译：具有流程同步和不可靠资源的资源分配系统的活动实施监督。

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摘要

A resource allocation system is characterized by a set of system resources, each available at a finite level, a set of part types that may be processed simultaneously through the system according to sequences of processing stages, with each stage requiring a predetermined set of the system resources, and a set of material handling devices. The underlying workflow logic, the resource request structure, and the reliability of the system resources constitute various aspects of research for the system.; Synchronizations commonly occur in workflows. A process may comprise several sub-processes independently until some synchronization stage is attained; at which point, sub-processes re-combine through merging and/or splitting and then continue as a new set. We consider resource allocation systems with process synchronizations. Resource allocation in this class of systems is complicated by the fact that quasi-liveness is NP-complete, implying that general algorithms for identifying resource allocation sequences to complete a single process will be super-polynomial. Thus, developing computationally tractable methods that coordinate resource allocation across sets of processes is a challenging research problem. In this work, we use a subclass of Petri nets called Generalized Augmented Marked Graphs to define the class of systems we are considering here. We then present a reachability algorithm that enumerates all possible sequences of resource allocations that are capable to complete a single process each and illustrate how to use a standard deadlock avoidance policy to coordinate resource allocation across processes when these enumerated sequences are available. Because sequence enumeration is exponential for the general class of systems, we next focus on developing polynomial methods that identify resource allocation sequences for a special resource allocation sub-class; namely, single-unit resource allocation systems with merging but no splitting.; We next look into deadlock and blocking problems in resource allocation systems with several unreliable system resources. Almost all work to date assumes that allocated resources do not fail in a system. In this work, however, we develop supervisory control policies to allocate resources such that the failures or repairs of any unreliable resources do not cause blocking to propagate through a system to effectively stall some portions of the system. Specifically, when an unreliable resource fails, all part types not requiring the failed resource must continue to produce at any time. As a failed resource is repaired, a smooth transition to upgraded operation must be ensured. To that end, the supervisory controller must ensure safety for the system while avoiding states that will not result in feasible initial states for a perturbed system when an unreliable resource fails. In the meantime, the controller must also avoid states that will not result in feasible initial states for an upgraded system when a failed unreliable resource is repaired. We examine properties that a supervisory controller must possess to deal effectively with these problems.
机译：资源分配系统的特征是一组系统资源（每个资源在有限级别上可用），一组零件类型，这些零件类型可以根据处理阶段的顺序通过系统同时进行处理，每个阶段都需要系统的预定集合资源和一套物料搬运设备。底层的工作流程逻辑，资源请求结构和系统资源的可靠性构成了系统研究的各个方面。同步通常发生在工作流中。一个过程可以独立地包括几个子过程，直到达到某个同步阶段为止。在这一点上，子流程通过合并和/或拆分进行重新组合，然后作为新集合继续进行。我们考虑具有流程同步的资源分配系统。此类系统中的资源分配非常复杂，因为准活动性是NP完全的，这意味着用于标识资源分配序列以完成单个过程的通用算法将是超多项式的。因此，开发在各过程集之间协调资源分配的易计算的方法是一个具有挑战性的研究问题。在这项工作中，我们使用Petri网的子类（称为广义增强标记图）来定义在此考虑的系统类。然后，我们提出一种可达性算法，该算法枚举所有可能完成一个进程的资源分配的所有可能序列，并说明当这些枚举序列可用时，如何使用标准的避免死锁策略来协调跨进程的资源分配。由于序列枚举对于一般系统类别而言是指数级的，因此我们接下来将重点关注开发多项式方法，该方法可为特殊资源分配子类标识资源分配序列。即具有合并但没有分裂的单单位资源分配系统。接下来，我们研究具有几种不可靠系统资源的资源分配系统中的死锁和阻塞问题。迄今为止，几乎所有工作都假定分配的资源在系统中不会失败。但是，在这项工作中，我们开发了监督控制策略来分配资源，以使任何不可靠资源的故障或修复都不会导致阻塞传播到系统中，从而有效地使系统的某些部分停顿下来。具体来说，当不可靠的资源发生故障时，不需要故障资源的所有零件类型都必须在任何时候继续生产。修复发生故障的资源时，必须确保平稳过渡到升级的操作。为此，监督控制器必须确保系统的安全性，同时避免在不可靠的资源发生故障时不会为受干扰的系统带来可行的初始状态的状态。同时，当故障的不可靠资源得到修复时，控制器还必须避免不会为升级后的系统带来可行的初始状态的状态。我们研究了监督员为有效处理这些问题而必须具备的属性。

著录项

  • 作者

    Chew, Song Foh.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Engineering Industrial.; Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 126 p.
  • 总页数 126
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 一般工业技术;机械、仪表工业;
  • 关键词

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