A distributed virtual factory in agile manufacturing environment

There is a growing recognition that current manufacturing enterprises must be agile, that is, capable of operating profitably in a competitive environment of continuously changing customer demands. The use of a virtual enterprise (VE) is becoming increasingly prevalent, and that has been made possible, in part, due to the significant advances in communication and information technology in recent years. A manufacturing system is one of the competitive factors that forms an effective VE. Therefore, for manufacturers wishing to obtain a contract in VE, it is crucial to present attractive and competitive offers to other coalition members. There are several criteria to these offers, such as cycle time, fulfilment of due date or quick shipping date, cost, and quality assurance for the ordered products. Manufacturing system simulation could endorse the basic estimates of the criteria for the strategic offer. The distributed simulation model concept provides practical solutions to facilitate such a large-scaled precise simulation model in the VE environment, because it is constructed as the integration of several manufacturing simulation models of each production module in the factory. As a solution to realize this integration, we propose a Distributed Virtual Factory (DVF) concept that consists of distributed precise simulation models connected by several synchronization mechanisms named Time Bucket algorithms. A DVF enables precise evaluations of the whole manufacturing system, especially in terms of the material flows. In this study, we introduce an Activity Based Costing (ABC) method into the DVF architecture to estimate the detailed cost analysis of the products. The methodology facilitates strategic enterprise management to prepare the request for the bids in the VE environment. The effectiveness of the proposed concept in agile manufacturing is discussed with simulation experiments.     

A DDoS Attack Situation Assessment Method via Optimized Cloud Model Based on Influence Function

The existing network security situation assessment methods cannot effectively assess the Distributed denial-of-service (DDoS) attack situation. In order to solve these problems, we propose a DDoS attack situation assessment method via optimized cloud model based on influence function. Firstly, according to the state change characteristics of the IP addresses which are accessed by new and old user respectively, this paper defines a fusion feature value. Then, based on this value, we establish a V-Support Vector Machines (V-SVM) classification model to analyze network flow for identifying DDoS attacks. Secondly, according to the change of new and old IP addresses, we propose three evaluation indexes. Furthermore, we propose index weight calculation algorithm to measure the importance of different indexes. According to the fusion index, which is optimized by the weighted algorithm, we define the Risk Degree (RD) and calculate the RD value of each network node. Then we obtain the situation information of the whole network according to the RD values, which are from each network nodes with different weights. Finally, the whole situation information is classified via cloud model to quantitatively assess the DDoS attack situation. The experimental results show that our method can not only improve the detection rate and reduce the missing rate of DDoS attacks, but also access the DDoS attack situation effectively. This method is more accurate and flexible than the existing methods.     

基于统计性QoS保证的数据包延时界调度算法

讨论了调度算法的性能指标，对目前基于业务流的调度算法的技术特点与性能优劣进行了分析和比较．重点研究了基于时延和丢包率的算法，并提出了一种基于数据包延时界（PDB）排列的调度策略，与WFQ及传统EDF算法进行了比较，证明业务端到端超时概率随网络带宽利用率的变化性能优于传统EDF算法．     

A distributed multi-agent environment for product design and manufacturing planning

This paper describes a multi-agent approach to the integration of product design, manufacturability analysis, and process planning in a distributed manner. The objective is to develop a distributed concurrent engineering system to allow geographically dispersed entities to work cooperatively towards overall system goals. In the paper, an agent-based concurrent engineering system concerning product design and manufacturing planning, and its fundamental framework and functions are presented. The proposed model considers constraints and requirements from the different product development cycles in the early development phases and fully supports the concept of design-for-manufacturability. This methodology uses conflict resolution (CR) techniques and design-improvement suggestions to refine the initial product design. The model comprises a facilitator agent, a console agent and six service agents. Each service agent is used to model different product development phases, and the console agent acts as an interacting interface between designers and the system, while the facilitator is responsible for the decomposition and dispatch of tasks, and resolving conflicts of poor designs. A prototype system for part design, manufacturability analysis, and process planning has been implemented. The performance of the prototype system shows that it could be extended to include other service agents, such as assemblability analysis, to become a comprehensive distributed concurrent engineering system for geographically dispersed customers and suppliers.     

基于Web Service构建分布式虚拟地理环境系统

在研究了分布式虚拟地理环境系统的特征和基于Web Service、GI Web Service实现分布式虚拟地理环境系统的优势的基础上,建立了基于Web Service的分布式虚拟地理环境系统的体系结构,最后开展了原型系统试验.结果证明,系统实现了在异构环境下的资源共享和协同工作,基本解决了以往C/S、B/S结构的系统中共享资源只能集中存储在服务器端等难点问题.     

反爆炸恐怖袭击防排爆技术综述

爆炸袭击是最残酷、最血腥、最难防范的恐怖活动,防排爆是反爆炸恐怖袭击最直接的技术手段,其中涉及搜爆、排爆、防爆等技术装备和方法。近年来,反爆炸恐怖袭击防排爆技术取得了很大进步,但还存在许多技术难题。本文主要分析了爆炸恐怖活动规律、搜排爆装备技术和防护技术现状,研究了爆炸物探测和防排爆的技术途径,针对现有装备技术的局限性提出了研究的方向和思路。     

Dynamic scheduling of production-assembly networks in a distributed environment

In complex manufacturing environments, meeting the due dates of the jobs and minimizing in process inventories are important performance metrics. One of the common characteristics of complex production systems is production-assembly network of operations. This paper presents an auction-based algorithm for simultaneous scheduling of all manufactured and assembled jobs in a dynamic environment, where the objective function is to minimize both the due date penalties associated with the final products and the inventory cost of the work in process. An auction-based approach using a Mixed-Integer Linear Programming (MILP) model to construct and evaluate the bids so that the auction mechanism mimics a Lagrangian relaxation-based subgradient optimization to ensure global optimality is proposed. The inner structure of the problem enables very efficient calculation of bids for each job or assembly. Using a full factorial experimental design the properties of the proposed algorithm are analyzed. Results show that the proposed auction based algorithm performs better than the popular dispatching rules and is more scalable than the MILP model or direct implementations of the subgradient algorithm. Furthermore, the proposed algorithm is designed to work in a dynamic environment.     

Auction-based distributed scheduling in a dynamic job shop environment

Developments in computing and communication technology coupled with the inability to address real-time issues in scheduling algorithms based on central control, has led to an interest in solving the problem of a distributed decision-making environment. This paper presents a new job shop formulation that schedules jobs using auctions for distributing control. A theoretical basis is presented for problem decomposition, bid construction, and bid evaluation for the auction using standard mathematical programming tools. Numerical results show that the auction-based approach outperforms the distributed dispatching approaches and can be used to create schedules for a wide range of scheduling objectives.     

Logical scheme improvement for maintaining replicated data in distributed environment

Abstract

Data can be replicated to improve availability and performance in a distributed environment. To ensure the consistency of the replicated data, many schemes have been proposed. Most of these schemes are designed based on the quorum set approach. However, some of them are dominated. Such schemes can be further improved. By using theoretical analysis, we devise a paradigm for refining quorum schemes for managing replicated data. We present two dominating alternatives to a recently proposed high performance scheme.     

Developing manufacturing ontologies for knowledge reuse in distributed manufacturing environment

The use of ontologies for knowledge sharing and distributed collaboration has been widely recognised in the knowledge modelling community, but the lack of a systematic and constructive methodology for developing manufacturing ontologies has impeded their wide usage for knowledge reuse in distributed manufacturing environments. This paper presents a constructive, two-level knowledge modelling approach to systematically develop manufacturing ontologies using both software engineering and Semantic Web paradigms. The UML/OCL (Unified Modeling Language/Object Constraint Language)-based object modelling is used first to serve as a graphical and structured basis for conceptual communication between domain experts and knowledge engineers. The OWL/SWRL (Web Ontology Language/Semantic Web Rule Language)-based ontology modelling then extends the UML/OCL-based object models with added semantics using a progressive, semantics-oriented knowledge acquisition method. An illustrative example for manufacturing ontology development in the manufacturing industry for producing electronic connectors is used to demonstrate the practicality of the proposed approach.     

Enhancing security of DICOM images during storage and transmission in distributed environment

Digital watermarking is proposed as a method to enhance medical data security. Medical image watermarking requires extreme care when embedding additional information within medical images, because the additional information should not degrade medical image quality. Doctors diagnose medical images by seeing Region of Interest (ROI). A ROI of a medical image is an area including important information and must be stored without any distortion. If a medical image is illegally obtained or if its content is changed, it may lead to wrong diagnosis. In our scheme a well-known technique least significant bit substitution (LSB) is adapted to fulfill the requirements of data hiding and authentication in medical images. The scheme divide Digital Imaging and Communications in Medicine (DICOM) image into two parts ROI and non-ROI (non-region of interest). The DS (Digital Signature) which include patient data and SOP Instance UID are embedded randomly into the LSB border of the image. The DWT (Discrete Wavelet Transform) of ROI-MSB (most significant bit) embedded into the LSB middle of the image. The Result shows the ability to hide and retrieve DS in non-ROI, while ROI, the most important area for diagnosis, is retrieved exactly at the receiver side.     

A CBFSA approach to resolve the distributed manufacturing process planning problem in a supply chain environment

In this competitive world cost and lead time reduction are of prime concern for manufacturing firms. To achieve this objective manufacturing entities are adopting several management philosophies such as Total Quality Management (TQM), just-in-time (JIT), and theory of constraints (TOC). The present paper addresses the advanced computer-aided process planning (ACAPP) problem in a distributed manufacturing supply chain environment and aims at cost and lead times reduction under several technological constraints. To deal with the complexity of the problem the constraint based fast simulated annealing (CBFSA) algorithm has been explored in this article. Extensive computations have been performed over the well-known benchmarks of advanced planning problems and the results obtained prove the superiority of the proposed algorithm over the prior approaches.     

Using short-time Fourier transform and wavelet packet filter banksfor improved frequency measurement in a Doppler robot tracking system

Previous research has shown that an ultrasonic tracking system using the Doppler effect can potentially track high-speed robot motion very accurately. However, ultrasound energy that is reflected by obstacles in the robot workspace can cause significant distortions in the frequency measurement. To reduce the distortions, a novel method for frequency measurement is described in this paper. This uses the short-time Fourier transform (STFT) to estimate the frequency of the interference signal. Then, the estimated frequencies are analyzed with an adaptive filter constructed with wavelet packet filter banks. Results are given that demonstrate great improvements in frequency measurement     

A procedure for estimating the statistical characteristics of streams of hacker attacks. The structure and determination of their fundamental properties

A procedure for estimating the statistical characteristics of ordinary streams of random events is proposed. This procedure was used to investigate the characteristics of hacker phishing attacks in the period from December 2008 to October 2010. A comparative investigation of the monthly dynamics of phishing attacks and attacks using malicious software, recorded in 2009, is described.     

A computational approach for the optimal conceptual design synthesis based on the distributed resource environment

Optimal conceptual design synthesis is the very starting and key phase in the product design. Its result is the optimal alternative in the solution space, and will be further completed and improved into the final product design scheme in the next detailed design works. With the progress of the Internet technology, a large number of design resources actually construct an increasingly growing distributed resource environment. If these rich resources can be fully introduced into the optimal conceptual design synthesis, the design efficiency and product innovation will be promoted largely. Therefore, a computational approach was proposed for the optimal conceptual design synthesis based on the distributed resource environment. In this approach, the distributed resource environment is modelled as a set of numerous functional units (FUs), and the optimal conceptual design synthesis is concluded into a process of generating the optimal objective FU chain. Here, the main workload is completed by a proposed computer algorithm. To prove the feasibility of this approach, a computer programme called Optimal Conceptual Design Synthesis System (OCDSS) was established. A garbage-powered lighting system was designed with OCDSS as an illustration.     

Assessment of information impacts in power system security against malicious attacks in a general framework

In the analysis of power systems security, recently a new concern related to possible malicious attacks caught much attention. Coordination among different transmission system operators (TSO) in an interconnected power system to counteract such attacks has become an important problem. This paper presents a general framework for describing the physical, cyber and decision-making aspects of the problem and their interrelations; within this framework, an analytic tool for the assessment of information impacts in handling on-line security after a malicious attack is proposed and discussed. The model is based on the socially rational multi-agent systems and the equilibrium of a fictitious play is considered to analyze the impacts of various levels of information available to the interconnected system operators on the outcomes of the decision-making process under attack. A 34-buses test system, with 3 systems interconnected by tie-lines, is presented to illustrate the model and compare the impacts of different information scenarios.     

Nanoindentations on conch shells of Gastropoda and Bivalvia molluscs reveal anisotropic evolution against external attacks

Nanoindentation method has been used to explore, at the nanoscale, the mechanical properties of four different representative types of conch shells belonging to the two biggest classes of molluscs, Gastropoda and Bivalvia, in order to compare nanohardness and Young's modulus with respect to the microstructural anisotropic architectures. For the experimental tests a Nano Indenter XP (MTS Nano Instruments, Oak Ridge TN) has been used. The mechanical tests have been carried out on the inner and outer surfaces of the shells, as well as on their cross-section, near to the inner/outer surfaces and in the middle layer. The results confirm the three layered anisotropic architecture of the investigated conchs. On each of these 5 surfaces, 2 x 5 indentations have been performed at different maximum depth: from 250 nm to 4 microm, with a step of 250 nm, for a total of 3200 tests. The numerous observations have been analysed applying an ad hoc modification of the Weibull Statistics, suggesting a natural evolution of the shells against external attacks.     

修正时延扩展卡尔曼滤波MIMO声纳目标跟踪方法研究

分布式多输入多输k~（Multiple．InputMultiple—Output,MIMO）声纳是一种通过MIMO技术规划时空信道来提高声纳探测性能的新型主动探测声纳体制。由于分布式MIMO声纳节点分布间隔大,水中声速较小,由各发射节点同步发射的测距信号将经过不同的时延到达目标,因此各接收节点测得的距离值分别对应于目标不同时刻的状态。常规的定位方法并没有考虑传播时延对测量值的影响,因而定位精度受到限制。提出了一种修正时延的扩展卡尔曼滤波方法（ModifiedExtendedKalmanFilter,MEKF）对分布式MIMO声纳系统中的移动目标进行跟踪。仿真结果表明,与常规的目标定位跟踪方法相比,该方法有定位精度高、收敛速度快、跟踪性能稳定的特点。