Adaptive Execution of Jobs in Computational Grid Environment

In a computational grid, jobs must adapt to the dynamically changing heterogeneous environment with an objective of maintaining the quality of service. In order to enable adaptive execution of multiple jobs running concurrently in a computational grid, we propose an integrated performance-based resource management framework that is supported by a multi-agent system (MAS). The multi-agent system initially allocates the jobs onto different resource providers based on a resource selection algorithm. Later, during runtime, if performance of any job degrades or quality of service cannot be maintained for some reason (resource failure or overloading), the multi-agent system assists the job to adapt to the system. This paper focuses on a part of our framework in which adaptive execution facility is supported. Adaptive execution facility is availed by reallocation and local tuning of jobs. Mobile, as well as static agents are employed for this purpose. The paper provides a summary of the design and implementation and demonstrates the efficiency of the framework by conducting experiments on a local grid test bed.     

基于概率时间自动机的异构多agent自适应运行时验证

多agent自适应系统在运行过程中需要根据环境进行自适应调整。异构agent能够提高agent的使用效率和降低系统的构建成本,但存在复杂的协作问题,因此提出一种基于概率时间自动机的异构多agent自适应系统运行时验证方法。该方法通过形式化描述异构agent的功能特征并融合环境中的随机因素构建概率时间自动机模型模拟自适应系统的运行过程;针对异构agent之间的协作逻辑制定安全约束条件以确保系统运行中状态迁移流程的安全性。通过模型检查结合运行时定量验证方法进行实验验证,在智能泊车系统案例中应用该方法。实验结果表明,agent之间协作逻辑的正确性可以有效保证系统运行时的稳定性,且相较于不使用运行时定量验证的初始系统在相同时间内正常运行的时间提升了21%左右。     

基于QMix的车辆云计算资源动态分配方法

城市交通智能化和通信技术的进步会产生大量基于车辆的应用,但目前车辆有限的计算资源无法满足车辆应用的计算需求与延迟性约束。车辆云（VC）可以高效地调度资源,从而显著降低任务请求的延迟与传输成本。针对VC环境下任务卸载与计算资源分配问题,提出一个考虑异质车辆和异质任务的计计资源分配算法。对到达的任务构建M/M/1队列模型与计算模型,并定义一个效用函数以最大化系统整体效用。针对环境中车辆地理分布的高度动态系统变化,提出基于双时间尺度的二次资源分配机制（SRA）,使用两个不同时间尺度的资源分配决策动作,对其分别构建部分可观测马尔可夫决策过程。两个决策动作通过执行各自的策略获得的奖励进行连接,将问题建模为两层计算资源分配问题。在此基础上提出基于二次资源分配机制的多智能体算法SRA-QMix求解最优策略。仿真结果表明,与深度确定性策略梯度算法对比,该算法的整体效用值和任务完成率分别提高了70%、6%,对于QMix和MADDPG算法分别应用SRA后的任务完成率分别提高了13%与15%,可适用于动态的计算资源分配环境。     

Data‐aware task scheduling on heterogeneous hybrid memory multiprocessor systems

In this paper, we propose a method about task scheduling and data assignment on heterogeneous hybrid memory multiprocessor systems for real‐time applications. In a heterogeneous hybrid memory multiprocessor system, an important problem is how to schedule real‐time application tasks to processors and assign data to hybrid memories. The hybrid memory consists of dynamic random access memory and solid state drives when considering the performance of solid state drives into the scheduling policy. To solve this problem, we propose two heuristic algorithms called improvement greedy algorithm and the data assignment according to the task scheduling algorithm, which generate a near‐optimal solution for real‐time applications in polynomial time. We evaluate the performance of our algorithms by comparing them with a greedy algorithm, which is commonly used to solve heterogeneous task scheduling problem. Based on our extensive simulation study, we observe that our algorithms exhibit excellent performance and demonstrate that considering data allocation in task scheduling is significant for saving energy. We conduct experiments on two heterogeneous multiprocessor systems. Copyright © 2016 John Wiley & Sons, Ltd.     

Real-time supply chain control via multi-agent adjustable autonomy

Real-time supply chain management in a rapidly changing environment requires reactive and dynamic collaboration among participating entities. In this work, we model supply chain as a multi-agent system where agents are subject to an adjustable autonomy. The autonomy of an agent refers to its capability to make and influence decisions within a multi-agent system. Adjustable autonomy means changing the autonomy of the agents during runtime as a response to changes in the environment. In the context of a supply chain, different entities will have different autonomy levels and objective functions as the environment changes, and the goal is to design a real-time control technique to maintain global consistency and optimality. We propose a centralized fuzzy framework for sensing and translating environmental changes to the changes in autonomy levels and objectives of the agents. In response to the changes, a coalition-formation algorithm will be executed to allow agents to negotiate and re-establish global consistency and optimality. We apply our proposed framework to two supply chain control problems with drastic changes in the environment: one in controlling a military hazardous material storage facility under peace-to-war transition, and the other in supply management during a crisis (such as bird-flu or terrorist attacks). Experimental results show that by adjusting autonomy in response to environmental changes, the behavior of the supply chain system can be controlled accordingly.     

An Extended Multi-Agent Negotiation Protocol

This article presents a task allocation protocol that is efficient in time and tolerates crash failures in multi-agent systems. The protocol is an extension of the negotiation protocol defined by Smith and Davis [25, 26] for task allocation. Our extension of the Contract Net Protocol (1) enables an agent to manage several negotiation processes in parallel; (2) optimizes the length of the negotiation processes among agents; (3) reduces the contractors' decommitment situations; (4) enables the detection of failures of an agent participating in a negotiation process and prevents a negotiation process with blocked agents.     

Using imbalance metrics to optimize task clustering in scientific workflow executions

Scientific workflows can be composed of many fine computational granularity tasks. The runtime of these tasks may be shorter than the duration of system overheads, for example, when using multiple resources of a cloud infrastructure. Task clustering is a runtime optimization technique that merges multiple short running tasks into a single job such that the scheduling overhead is reduced and the overall runtime performance is improved. However, existing task clustering strategies only provide a coarse-grained approach that relies on an over-simplified workflow model. In this work, we examine the reasons that cause Runtime Imbalance and Dependency Imbalance in task clustering. Then, we propose quantitative metrics to evaluate the severity of the two imbalance problems. Furthermore, we propose a series of task balancing methods (horizontal and vertical) to address the load balance problem when performing task clustering for five widely used scientific workflows. Finally, we analyze the relationship between these metric values and the performance of proposed task balancing methods. A trace-based simulation shows that our methods can significantly decrease the runtime of workflow applications when compared to a baseline execution. We also compare the performance of our methods with two algorithms described in the literature.     

一种基于P学习的分布式并行多任务分配算法

并行多任务分配是多agent系统中极具挑战性的课题, 主要面向资源分配、灾害应急管理等应用需求, 研究如何把一组待求解任务分配给相应的agent联盟去执行. 本文提出了一种基于自组织、自学习agent的分布式并行多任务分配算法, 该算法引入P学习设计了单agent寻找任务的学习模型, 并给出了agent之间通信和协商策略. 对比实验说明该算法不仅能快速寻找到每个任务的求解联盟, 而且能明确给出联盟中各agent成员的实际资源承担量, 从而可以为实际的控制和决策任务提供有价值的参考依据.     

多Agent自动协商中机器学习的应用研究

目前将机器学习理论应用到多Agent自动协商系统中已成为电子商务领域的最新研究课题。本文即是利用贝叶斯法则来更新协商中的环境信息（即信念），利用强化学习中的Q学习算法生成协商中的提议，建立了一个具有学习机制的多Agent自动协商模型。并且封传统Q学习算法追行了扩充，设计了基于Agent的当前信念和最近探索盈余的动态Q学习算法。实验验证了算法的收敛性。     

Negotiating context information in context-aware systems

Context-aware environments must allow adaptive and autonomous access to context information. This multi-agent middleware uses a negotiation protocol and ontology model to make the environment more easily personalized at runtime and adapted and managed at provisioning time. In a pervasive environment, a wide range of devices and resources use heterogeneous networks to perform the tasks involved in spontaneous ad hoc communication. The environment's infrastructure must therefore make available a rich set of computing capabilities and services at all times and in all locations in a transparent, integrated, and convenient way. Context provides perceptual information about the location and status of the people, places, and other devices in the environment.     

A Complex Networked Method of Sorting Negotiation Demand Based on Answer Set Programs

With the development of big data science, handling intensive knowledge in the complex network becomes more and more important. Knowledge representation of multi-agent negotiation in the complex network plays an important role in big data science. As a modern approach to declarative programming, answer set programming is widely applied in representing the multi-agent negotiation knowledge in recent years. But almost all the relevant negotiation models are based on complete rational agents, which make the negotiation process complex and low efficient. Sorting negotiation demands is the most key step in creating an efficient negotiation model to improve the negotiation ability of agents. Traditional sorting method is not suitable for the negotiation in the complex network. In this paper, we propose a complex networked negotiation, which can show the relationships among demands, and then a sorting method of negotiation demands is proposed based on demand relationships. What’s more, we use the betweenness of literals and the boundary co-efficient of rules to evaluate the importance of demands and rules.     

Collaborative assignment using belief-desire-intention agent modeling and negotiation with speedup strategies

In this paper, we propose a distributed agent model that applies belief-desire-intention (BDI) reasoning and negotiation for addressing the linear assignment problem (LAP) collaboratively. In resource allocation, LAP is viewed as seeking a concurrent allocation of one different resource for every task to optimize a linear sum objective function. The proposed model provides a basic agent-based foundation needed for efficient resource allocation in a distributed environment. A distributed agent algorithm that has been developed based on the BDI negotiation model is examined both analytically and experimentally. To improve performance in terms of average negotiation speed and solution quality, two initialization heuristics and two different reasoning control strategies are applied, with the latter yielding different variants of the basic algorithm. Extensive simulations suggest that all the heuristic-algorithm combinations can produce a near optimal solution soon enough in some specific sense. The significance and applicability of the research work are also discussed.     

Automatic task mapping and heterogeneity-aware fault tolerance: The benefits for runtime optimization and application development

The best mapping of a task to one or more processing units in a heterogeneous system depends on multiple variables. Several approaches based on runtime systems have been proposed that determine the best mapping under given circumstances automatically. Some of them also consider dynamic events like varying problem sizes or resource competition that may change the best mapping during application runtime but only a few even consider that task execution may fail. While aging or overheating are well-known causes for sudden faults, the ongoing miniaturization and the growing complexity of heterogeneous computing are expected to create further threats for successful application execution. However, if properly incorporated, heterogeneous systems also offer the opportunity to recover from different types of faults in hardware as well as in software. In this work, we propose a combination of both topics, dynamic performance-oriented task mapping and dependability, to leverage this opportunity. As we will show, this combination not only enables tolerating faults in hardware and software with minor assistance of the developer, it also provides benefits for application development itself and for application performance in case of faults due to a new metric and automatic data management.     

An economics-based negotiation scheme among mobile devices in mobile grid

In this paper, we propose an economics-based distributed negotiation scheme among mobile devices in mobile grid. In our model, there are energy negotiation and transactions between buyer devices and seller devices. Dynamic allocation of energy resources in mobile grid is performed through online transactions within markets. Mobile devices can be sellers and buyers that use optimization algorithms to maximize predefined utility functions during their transactions. Seller device agents sell the underlying energy resources of the mobile device. Buyer device agent makes buying decisions within the budget constraints to acquire energy resources. An economics-based negotiation algorithm among mobile devices is proposed. The proposed algorithm decomposes mobile grid system optimization problem into a sequence of two sub-problems. In the simulation, the performance evaluation of economics-based negotiation algorithm is evaluated.     

面向协同任务的多UCAV分布式任务分配与协调技术

对多架无人作战飞机 (Unmanned combat aerial vehicle, UCAV) 分布式控制中的任务分配与任务协调问题开展研究. 采用合同网实现任务执行过程中的任务分配. 通过对合同网进行扩展, 使 UCAV 能够在招标和竞标的同时处理任务间的时间约束. 设计了一种新的部分全局规划协商机制, 能够更有效地对执行相关任务的 UCAV 的任务计划进行协调. 通过 Petri 网建模方法, 将两种协商机制模型化为 Petri 网并分析了协商过程的正确性与协商结果的可行性. 仿真实验验证了方法的有效性.     

An efficient distributed randomized algorithm for solving large dense symmetric indefinite linear systems

Randomized algorithms are gaining ground in high-performance computing applications as they have the potential to outperform deterministic methods, while still providing accurate results. We propose a randomized solver for distributed multicore architectures to efficiently solve large dense symmetric indefinite linear systems that are encountered, for instance, in parameter estimation problems or electromagnetism simulations. The contribution of this paper is to propose efficient kernels for applying random butterfly transformations and a new distributed implementation combined with a runtime (PaRSEC) that automatically adjusts data structures, data mappings, and the scheduling as systems scale up. Both the parallel distributed solver and the supporting runtime environment are innovative. To our knowledge, the randomization approach associated with this solver has never been used in public domain software for symmetric indefinite systems. The underlying runtime framework allows seamless data mapping and task scheduling, mapping its capabilities to the underlying hardware features of heterogeneous distributed architectures. The performance of our software is similar to that obtained for symmetric positive definite systems, but requires only half the execution time and half the amount of data storage of a general dense solver.     

基于多Agent的众包任务推荐系统建模与仿真

为了让众包平台用户更方便准确地搜寻到合适任务,促进其能力水平提升,解决众包任务推荐动态性等问题,提出了一种基于多Agent的众包任务推荐系统。首先,基于众包平台建立多Agent任务推荐模型,提出了模型设计思路与模型框架,并进一步阐述了各Agent功能、相互作用关系与相关算法;其次,提出众包用户能力水平提升相关算法;最后,利用NetLogo仿真软件进行验证。结果表明,众包任务推荐系统可对用户能力水平的提升起到促进作用,证明了在众包平台引入推荐系统的必要性。并且分析了多Agent技术可提升推荐系统的动态性、智能性与灵活性等整体性能,促进了众包平台数据的管理与维护。     

基于SOA的多Agent协商服务及其应用

在简述一种融合了面向服务架构和多Agent协商系统特点的新的协商模型——基于面向服务架构的多Agent协商模型的基础上，设计了该协商模型的多Agent协商服务端，阐述了Agent中协商推理机在协商中的基本过程。面向服务架构的协商服务端与协商Agent管理平台组合起来，搭建起支持开放环境并开展协商的软件应用环境，实现了基于面向服务架构的多Agent协商模型在电子商务中的 应用。     

Negotiation on Data Allocation in Multi-Agent Environments

In this paper, we consider the problem of data allocation in environments of self-motivated servers, where information servers respond to queries from users. New data items arrive frequently and have to be allocated in the distributed system. The servers have no common interests, and each server is concerned with the exact location of each of the data items. There is also no central controller. We suggest using a negotiation framework which takes into account the passage of time during the negotiation process itself. Using this negotiation mechanism, the servers have simple and stable negotiation strategies that result in efficient agreements without delays. We provide heuristics for finding the details of the strategies which depend on the specific settings of the environment and which cannot be provided to the agents in advance. We demonstrate the quality of the heuristics, using simulations. We consider situations characterized by complete, as well as incomplete, information and prove that our methods yield better results than the static allocation policy currently used for data allocation for servers in distributed systems.     

Application of the multi-agent approach in production planning and modelling

The paper describes an experimental multi-agent system developed for and aimed at a computer-supported project-oriented production planning. The system is based on a heterogeneous hierarchy of agents of three types that reflect the managerial structure of the manufacturing enterprise. To improve the system efficiency, a new formalism—called tri-base model—of the multi-agent internal communication/negotiation mechanism has been introduced. The tri-base model that has been tested in an industrial environment is treated in detail in the paper.