Formal verification of negotiation protocols for multi-agent manufacturing systems

Formal verification is an important means of tackling behavioural problems such as deadlocks in multi-agent systems. This paper is concerned with the role played by formal verification in the simulation-based performance analysis of multi-agent manufacturing systems. A discrete-event simulation case study is presented to show how varying certain timing parameters of the agent negotiation protocol affects the performance of a multi-agent manufacturing system as well as the chance of getting deadlocks among the software agents. When one tries to determine the optimal values of these timing parameters based on the simulation results, formal verification can help refine the results by confirming whether deadlocks among software agents are indeed possible for particular parameter values. This involves modelling the system's real-time behaviour according to the simulation model and applying the techniques and tools of model checking.     

Assertion checking environment (ACE) for formal verification of C programs

In this paper we describe an Assertion Checking Environment (ACE) for compositional verification of programs, which are written in an industrially sponsored safe subset of C programming language called MISRA C [Guidelines for the Use of the C Language in Vehicle Based Software, 1998]. The theory is based on Hoare logic [Commun. ACM 12 (1969) 576] and the C programs are verified using static assertion checking technique. First the functional specifications of the program, captured in the form of pre- and post-conditions for each C function, are derived from the specifications. These pre- and post-conditions are then introduced as assertions (also called annotations or formal comments) in the program code. The assertions are then proved formally using ACE and theorem proving tool called Stanford Temporal Prover [The Stanford Temporal Prover User's Manual, 1998]. ACE has been developed by us and consists mainly of a translator c2spl, a GUI and some utility programs. The technique and tools developed are targeted towards verification of real-time embedded software.     

Hybrid Petri-nets for modelling and performance evaluation of supply chains

Modelling and analysis of complex and co-ordinated supply chains is a crucial task due to its inherent complexity and uncertainty. Therefore, the current research direction is to devise an efficient modelling technique that maps the dynamics of a real life supply chain and assists industrial practitioners in evaluating and comparing their network with other competing networks. Here an effective modelling technique, the hybrid Petri-net, is proposed to efficiently handle the dynamic behaviour of the supply chain. This modelling methodology embeds two enticing features, i.e. cost and batch sizes, in deterministic and stochastic Petri-net for the modelling and performance evaluation of supply chain networks. The model is subsequently used for risk management to investigate the issues of supply chain vulnerability and risk that has become a major research subject in recent years. In the test bed, a simple productive supply chain and an industrial supply chain are modelled with fundamental inventory replenishment policy. Subsequently, its performance is evaluated along with the identification and assessment of risk factors using analytical and simulation techniques respectively. Thus, this paper presents a complete package for industrial practitioners to model, evaluate performance and manage risky events in a supply chain.     

MANET QoS介质访问控制策略MAQF/MAC及其仿真研究

要实现移动Ad-Hoc网络MANET民用化，必然解决其MAC层的QoS创立。MAQF／MAC是一种新的MANET自适应QoS介质访问控制策略，该策略可以实时动态地测试网络资源，及时调整业务流对资源的访问和占用。本文着重从仿真实现角度，对MAQF／MAC协议的原理，预留表结构，QoS路由，压缩算法等问题进行探讨。仿真结果表明，MAQF／MAC在资源利用率和分级服务的QoS保障能力等方面明显优于MACA／PR。     

对JJG 229检定规程检定方法差错的实验验证

依据JJG 229——2010《工业铂、铜热电阻》检定规程规定的条件和方法,采用两支标称电阻值(Rtp)为25Ω的标准铂电阻温度计作标准,多支Pt100型工业铂热电阻作被检样品,两个不同准确度的测量仪器,完成两种检定方法比较试验。试验时标准器分别用自测Rtp值和上级证书值,用比较法完成对工业铂热电阻的检定。从结果可以看出:用自测标准Rtp值检定,增加的结果偏差是用上级证书值的5倍以上,表明标准器由从本级标准装置赋值开展检定是不科学的,其效果可能南辕北辙。     

Directional routing protocols for ad-hoc networks

A directional routing approach for multihop ad-hoc networks, is presented which has been applied to two on-demand routing protocols: namely dynamic source routing (DSR) and ad-hoc on-demand distance vector routing (AODV). Both DSR-based and AODV-based directional routing protocols are designed to balance the tradeoff between co-channel interferences from nodes hops away and the total power consumed by all the nodes. In order to select the best route, three metrics are considered in the route discovery process. They consist of hop count, power budget and overlaps between adjacent beams. By exploiting the direction of directional antennas, both routing protocols are capable of reducing overlaps between beams of the nodes along the route, thus eliminating interference. Arbitrary networks and random networks are considered in the simulations. The results show considerable performance gains for transmission of real-time traffic over ad hoc networks.     

Two incremental relaying protocols for cooperative networks

The authors investigate a cooperative network with three terminals. By exploiting a simple two-bit feedback message from the destination, two incremental relaying protocols are proposed, namely incremental selection amplify-and-forward (ISAF) and joint incremental selection relaying (JISR) with an aim to balance the load between the source and the relay. The authors derive the asymptotic outage probabilities of the two new protocols and find them to be lower than that of the incremental amplify-and-forward (IAF) protocol, which has been identified as the best protocol so far. Moreover, the spectral efficiencies of ISAF and JISR match that of IAF. Simulation results have verified the asymptotic performance of the protocols and have shown that JISR outperforms ISAF and IAF over all signal-to-noise ratio values.     

经纬仪自动检定系统研究

介绍了一种旨在提高经纬仪检定效率和精度的经纬仪自动检定系统,叙述了其组成、工作原理和软件设计,着重介绍了其独特的光学读数图像自动识别装置及计算机的数据自动采集,并对系统的测量不确定度进行了评定。实践证明,系统完全符合经纬仪检定的要求,大大降低了检定人员的劳动强度,为检定工作自动化程度的提高提供了一个有用的借鉴。     

Knowledge verification for fuzzy expert systems

Abstract

The introduction and use of fuzzy logic has strengthened knowledge representation and reasoning capability in expert systems; nevertheless, it also increases the complexity and difficulty of knowledge verification, which is known to be an important issue for building reliable and high performance expert systems. In the past decade, knowledge verification problems, e.g., redundancy, conflict, circularity and incompleteness of knowledge, have been widely discussed from the viewpoint of using binary logic; nevertheless, the issue of verifying fuzzy knowledge is seldom discussed. In this paper, we attempt to detect potential structural errors among fuzzy rules by proposing a fuzzy verification algorithm. Moreover, a system for verifying fuzzy knowledge base has been developed based on the novel approach.     

Effectiveness of formal reliability programmes

The development of complex yet highly reliable systems is one of the greatest technical and management challenges of our time. Because such systems are often developed and manufactured for official agencies, and to their specifications, it is necessary to impose controls that will ensure achievement of a performance parameter which is neither predictable nor measurable during development. Since failure is a stochastic process, statistical and actuarial techniques have been developed, but these have been emphasized too much in official reliability programmes.     

Commissioning and constancy protocols for digital angiographic units

During the European Concerted Action SENTINEL 'Safety and Efficacy for New Techniques and Imaging using New Equipment to Support European Legislation', protocols for commissioning and constancy tests for dynamic digital flat detectors angiography units have been developed in order to harmonise practice among the European counties. The commissioning protocol includes measurements on X-ray tube and generator, patient and detector radiation dose and image quality. The constancy protocol is based on the dose and image quality measurements. The commissioning protocol was tested by SENTINEL partners who expressed an interest in checking their dynamic digital systems using this protocol. The results of basic tests are reported.     

万用表半自动检定系统的实现

文章介绍了以D030多功能校准仪，Fluke8840A,智能转换器等组成的万用表半自动检定系统，并详细阐述了智能变换器的电路设计和工作原理。     

材料试验机检定结果的评定

首先对材料试验机示值误差进行了分析，然后根据所采用的不同检定方法，构造了两种误差分析的数学模型，并在其中一种数学模型的基础上进行了不确定度来源的确定，从中找到了不确定度的主要来源是由标准测力仪、检测时数据的不重复性、指示装置的分辨率等三方面所引入的，进一步对各种来源进行量化分析，对总不确定度进行合成，得到一套合理化的评定方法，最后通过实例进行了说明。