High level architecture evolved modular federation object model

To improve the agility, dynamics, composability, reusability, and development efficiency restricted by monolithic federation object model （FOM）, a modular FOM is proposed by high level architecture （HLA） evolved product development group. This paper reviews the state-of-the-art of HLA evolved modular FOM. In particular, related concepts, the overall impact on HLA standards, extension principles, and merging processes are discussed. Also permitted and restricted combinations, and merging rules are provided, and the influence on HLA interface specification is given. The comparison between modular FOM and base object model （BOM） is performed to illustrate the importance of their combination. The applications of modular FOM are summarized. Finally, the significance to facilitate compoable simulation both in academia and practice is presented and future directions are pointed out.

Architecture of HLA Based Distributed Virtual Geographic Environment

Integrating the theory of distributed virtual geographic environment (DVGE) and high level architecture(HLA), the architecture of DVGE based on HLA is designed. The data flow and the object models of the architecture are also discussed. The architecture basically meets the need of DVGE in real-time communication, distribution, collaboration, reusing and interoperation, expansion, and standard.

Theory and Implementation of Distributed Visual Simulation

The development process as well as the core theory of distributed interactive simulation and high level architecture are discussed, and combined with graphics features, a system of real time distributed visual simulation is established. Based on computer network, simulation platform is built by installing related software and modeling object, and the interactive functions are extended by programming. A set of solutions for building a distributed visual simulation system that include both hardware and software are put forward, and a practical instance is also provided. The whole building process can be summarized into two steps that are scheme consideration and system realization.

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.

Natural variation of hormone levels in Arabidopsis roots and correlations with complex root architecture

Studies on natural variation are an important tool to unravel the genetic basis of quantitative traits in plants. Despite the significant roles of phytohormones in plant development, including root architecture, hardly any studies have been done to investigate natural variation in endogenous hormone levels in plants. Therefore, in the present study a range of hormones were quantified in root extracts of thirteen Arabidopsis thaliana accessions using a ultra performance liquid chromatography triple quadrupole mass spectrometer. Root system architecture of the set of accessions was quantified, using a new parameter （mature root unit） for complex root systems, and correlated with the phytohormone data. Significant variations in phytohormone levels among the accessions were detected, but were remarkably small, namely less than three-fold difference between extremes. For cytokinins, relatively larger variations were found for ribosides and glucosides, as compared to the free bases. For root phenotyping, length-related traits--lateral root length and total root length--showed larger variations than lateral root number-related ones. For root architecture, antagonistic interactions between hormones, for example, indole-3-acetic acid to trans-zeatin were detected in correlation analysis. These findings provide conclusive evidence for the presence of natural variation in phytohormone levels in Arabidopsis roots, suggesting that quantitative genetic analyses are feasible.

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.

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 Optimization Technique for PMF Estimation in Approximate Circuits

As an emerging computing technology,approximate computing enables computing systems to utilize hardware resources efficiently.Recently,approximate arithmetic units have received extensive attention and have been employed as hardware modules to build approximate circuit systems,such as approximate accelerators.In order to make the approximate circuit system meet the application requirements,it is imperative to quickly estimate the error quality caused by the approximate unit,especially in the high-level synthesis of the approximate circuit.However,there are few studies in the literature on how to efficiently evaluate the errors in the approximate circuit system.Hence,this paper focuses on error evaluation techniques for circuit systems consisting of approximate adders and approximate multipliers,which are the key hardware components in fault-tolerant applications.In this paper,the characteristics of probability mass function(PMF)based estimation are analyzed initially,and then an optimization technique for PMF-based estimation is proposed with consideration of these features.Finally,experiments prove that the optimization technology can reduce the time required for PMF-based estimation and improve the estimation quality.

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.