基于HLA分布式仿真的Web服务化

HLA虽然能够简化各类仿真系统的互操作和重用,但是接口规范与编程语言的绑定、缺乏与商业技术的融合等阻碍了它在商业领域的广泛应用,Web服务具有平台和厂商独立等良好特性,实现基于HLA分布式仿真的Web服务化能够将Web服务的优势附加给HLA。该文在分析了HLA不足和Web服务优势的基础上,提出了HLA Web服务化,对比了互操作在两个上下文中的差异,分析了实现HLA Web服务化的三个层次;之后,概述了相关研究,重点讨论了实现Web使能RTI的关键技术问题及其解决方案;最后,设计了原型系统,测试结果显示原型系统能够初步实现RTI的Web服务化。

Dynamic Multicast Grouping Approach in HLA-Based Distributed Interactive Simulation

In order to improve the efficiency of data distributed management service in distributed interactive simulation based on high level architecture (HLA) and to reduce the network traffic and save the system resource, the approaches of multicast grouping in HLA-based distributed interactive simulation are discussed. Then a new dynamic multicast grouping approach is proposed. This approach is based on the current publication and subscription region in the process of simulation. The results of simulation experiment show that this approach can significantly reduce the message overhead and use fewer multicast groups.

Dynamic Region Updating Strategy in HLA-Based Distributed Interactive Simulation

The HLA(high level architecture)-based distributed interactive simulation uses interest management mechanism to reduce the traffic on network and improve the system scalability. Making region updating occur only when needed can improve the interest management. Typically a static threshold is defined before simulation to trigger the region updating. Now a dynamic threshold is used to trigger region updating , the threshold is adapted by the real-time massage in simulation, named as update lifetime. The result of experiment shows that this policy can overcome the weak point of static threshold and can meet the requirements of bandwidth and simulation correctness.

Hardware-in-the-loop simulation of communication networks

To enhance the fidelity and accuracy of the simulation of communication networks,hardware-in-the-loop（HITL） simulation was employed.HITL simulation methods was classified into three categories,of which the merits and shortages were compared.Combing system-in-the-loop（SITL） simulation principle with high level architecture（HLA）,an HITL simulation model of asynchronous transfer mode（ATM） network was constructed.The throughput and end-to-end delay of all-digital simulation and HITL simulation was analyzed,which showed that HITL simulation was more reliable and effectively improved the simulation credibility of communication network.Meanwhile,HLA-SITL method was fast and easy to achieve and low-cost during design lifecycle.Thus,it was a feasible way to research and analyze the large-scale network.

An Emulating Environment for Network Management of Space Network

An emulating environment for network management of the space network was presented. The emulating environment was developed with node-link model. The nodes of the satellite entities were controlled by the controlling network, which consist of sets of HLA/RTI based federates. These federates described the different aspect of the attributes of the satellites, such as orbit coordinate, routing table and the chain budget. We described the architecture of the emulation environment and the software design of federates. We measured the response time of the protocol data units and verified the detecting of the network topology in the environment. The environment was open that the on board router and the simulator of satellite link which developed by third party could be integrated.

AN EFFECTIVE WAY TO CONTROL CONGESTION FOR RTI WITH HYBRID ARCHITECTURE

Congestions brought by data explosion may suffer system performance or even cause fatal errors in large-scale simulation systems.This paper analyzes the reasons of generating congestion with queuing theory,and proposes a novel congestion control approach for RTI with hybrid architecture,including framework,sampling policy,queue length predicting,and congestion control algorithm.The framework promotes the usage of federate resources,and improves the performance of HLA simulation systems by dynamically distributing loads on RTIG and LRCs(Local RTI Components).At last,experimental results say that the proposed approach is a flexible,simple and efficient way to control congestion in RTI with hybrid architecture.

An Intelligent Agent Approach to Adaptive Project Management

This paper presents the initial steps to integrating a distributed discrete event simulation system with a framework for intelligent software agents. The resulting system has a simulation component that is based on the high-level architecture (HLA) and an agent component that implements the belief-desire-intention (BDI) approach to agent modelling. The architecture is connected to a real-time information source. The framework was successfully applied to a real-life monitoring system for a tunnel-boring machine excavation project that helped with forecasting and managing the project timelines in response to the changes in the uncertain excavation environment. This project is presented as a test case and demonstrates encouraging results for integrative modelling of large-scale problems with elements of uncertainty.

LoI:Effcient relevance evaluation and filtering for distributed simulation

In large-scale distributed simulation, thousands of objects keep moving and interacting in a virtual environment, which produces a mass of messages. High level architecture （HLA） is the prevailing standard for modeling and simulation. It specifies two publish-subscribe mechanisms for message filtering： class-based and value-based. However, the two mechanisms can only judge whether a message is relevant to a subscriber or not. Lacking of the ability to evaluate the relevance, all relevant messages are delivered with the same priority even when congestion occurs. It significantly limits the scalability and performance of distributed simulation. Aiming to solve the relevance evaluation problem, speed up message filtering, and filter more unnecessary messages, a new relevance evaluation mechanism Layer of Interest （Lol） was proposed by this paper. Lol defines a relevance classifier based on the impact of spatial distance on receiving attributes and attribute values. An adaptive publish-subscribe scheme was built on the basis of Loh This scheme can abandon most irrelevant messages directly. Run-time infrastructure （RTI） can also apply congestion control by reducing the frequency of sending or receiving object messages based on each objects＇ Loh The experiment results verify the efficiency of message filtering and RTI congestion control.