Hierarchical Fuzzy Systems for Function Approximation on Discrete Input Spaces With Application

This paper investigates the capabilities of hierarchical fuzzy systems to approximate functions on discrete input spaces. First, it is shown that any function on a discrete space has an arbitrary separable hierarchical structure and can be naturally approximated by hierarchical fuzzy systems. As a by-product of this result, a discrete version of Kolmogorov's theorem is obtained; second, it is proven that any function on a discrete space can be approximated to any degree of accuracy by hierarchical fuzzy systems with any desired separable hierarchical structure. That is, functions on discrete spaces can be approximated more simply and flexibly than those on continuous spaces; third, a hierarchical fuzzy system identification method is proposed in which human knowledge and numerical data are combined for system construction and identification. Finally, the proposed method is applied to the market condition performance modeling problem in site selection decision support and shows the better performance in both accuracy and interpretability than the regression and neural network approaches. In additions, the reason and mechanism why hierarchical fuzzy systems outperform regression and neural networks in this type of application are analyzed.      

Indexing and retrieval in machining process planning using case-based reasoning

To reduce the manufacturing time of a product, one effective way to develop a machining process plan for a new part is to retrieve a relevant case of process planning similar to a new desired part and then adapt the retrieved case to meet the new requirements. This paper proposes a mechanism for retrieval of process planning cases. The core of the retrieval mechanism contains: (1) a feature-based representation of a part and cutting processes; (2) indexing of a part; (3) a feature hierarchical structure based on cutting processes; and (4) a similarity metric used to measure the similarity between a new desired part and any old part in the case base. The application domain here is for axisymmetric part machining. A prototype based on the retrieval mechanism is implemented on a Sun workstation using the ACIS 3D-Toolkit from Spatial Technology Inc.     

光栅刻划机金刚石刀具抬落机构控制系统

为了改善传统机械式光栅刻划机的刻划性能,提出了一种新型光栅刻划机金刚石刀具抬落机构。介绍了光栅刻划机及抬落刀机构结构组成,并根据需求分析选用压电陶瓷平台作为执行器件。搭建了一套抬落刀控制系统并完成硬件设计,针对光栅刻划工艺需求,设计抬落刀控制系统软件。系统采用总线通信方式,制定串口通信协议。结果表明,该新型机构机械结构简单、可实时控制、精度高、无振动和发热,提高了刻划光栅的质量和刻划效率。为了改善传统机械式光栅刻划机的刻划性能,提出了一种新型光栅刻划机金刚石刀具抬落机构。介绍了光栅刻划机及抬落刀机构结构组成,并根据需求分析选用压电陶瓷平台作为执行器件。搭建了一套抬落刀控制系统并完成硬件设计,针对光栅刻划工艺需求,设计抬落刀控制系统软件。系统采用总线通信方式,制定串口通信协议。结果表明,该新型机构机械结构简单、可实时控制、精度高、无振动和发热,提高了刻划光栅的质量和刻划效率。     

Modularization of model transformations through a phasing mechanism

In recent years a great effort has been devoted to understanding the nature of model transformations. As a result, several mechanisms to improve model transformation languages have been proposed. Phasing has been mentioned in some works as a rule scheduling or organization mechanism, but without any detail. In this paper, we present a phasing mechanism in the context of rule-based transformation languages. We explain the structure and the behavior of the mechanism, and how it can be integrated in a language. We also analyze how the mechanism promotes modularity, internal transformation composition and helps to solve usual transformation problems. Besides, we show several examples of application to illustrate the usefulness of the mechanism.     

Maximal Static Expansion

Memory expansions are classical means to extract parallelism from imperative programs. However, current techniques require some runtime mechanism to restore data flow when expansion maps have two definitions reaching the same use to two different memory locations (e.g., functions in the SSA framework). This paper presents an expansion framework for any type of data structure in any imperative program, without the need for dynamic data flow restoration. The key idea is to group together definitions that reach a common use. We show that such an expansion boils down to mapping each group to a memory cell.     

Modified Even-Swaps: A novel,clear, rational and an easy-to-use mechanism for multi-issue negotiation

“Even-Swaps” is a well-known and easy-to-use trade-off methodology which provides several useful features to decision makers. It allows them to find the difference among alternatives in terms of any issue under consideration. In a typical negotiation environment, allocating these differences in terms of a bargainable issue can help the negotiators to clarify the agreement area for each alternative. This allocation can contribute to make bargaining decisions more rationally. However, this feature could not be used in the original version of the Even-Swaps method because of its rigid structure that tries to reveal only the best alternative. The original Even-Swaps method also provides several hypothetical questions to decision makers while performing issue trade-offs. It is believed that the original Even-Swaps method can be improved upon (adapted) by forwarding the hypothetical questions to sellers and by developing a modified/flexible structure which considers all bargainable alternatives. With these modifications are successfully realized, an agent can generate counter offers and interact with sellers for bargaining by means of an appropriate automated-negotiation mechanism. The development of an automated & multi-issue negotiation-mechanism for bargaining also presents unique opportunities for the re-evolution of consumers into customers while contributing to the buyer–seller interactions. In this study, we present a novel multi-issue negotiation mechanism which adapts a modified Even-Swaps method that finds the differences among alternatives and makes use of those differences to assess the value of multi-issue offers. It uses a fuzzy inference system for bargaining on several issues simultaneously. In order to accomplish the steps of the proposed mechanism, a supplementary semi-automated decision-aid tool, so called: “Modified Even-Swaps Agent (MESA)” is developed. A real case-study is presented step by step in order to demonstrate how the proposed mechanism works.     

Alightweight class library for extended persistent object management in C++

When applications must keep their data structures persistent, additional effort beyond transient modeling is necessary to realize suitable persistent storage. The most convenient approach is the use of a persistent programming language (PPL), which offers internal mechanisms for storing and loading data transparently for the application programmer. An alternative to a PPL is a universal programming language that has been extended by persistence concepts for any data typesThis paper introduces an extended generic mechanism that abstracts necessary functionality for realizing persistence of any C++ object structure. First, we discuss general problems of persistent storage and the motivation for this approach. The design aspects and the reasons for special features are described in detail with the data and implementation insides. Finally, we sketch the persistent data structure and present the integration of the library in three different example programs.     

基于分簇的低功耗多跳WSN时间同步机制

针对典型同步算法中同步开销大的问题,提出一种基于分簇的低功耗时间同步机制(LCTS),将单向广播同步和双向成对同步机制相结合,在分级网络的基础上给出一种分簇算法,将LCTS扩展到多跳网络中,并对时钟漂移进行估计和补偿。仿真结果证明,该机制在不引起同步滞后的前提下,能减少同步报文开销,保证良好的同步精度。     

A Parallel and Nonblocking Updating Mechanism for Replicated Directory Files in Distributed Systems

This paper presents a new and efficient method for consistency control of replicated directory files. By investigating the special consistency requirements and the data structure of directory files, we design a parallel and nonblocking updating mechanism for the management of directory files. Compared with other consistency control mechanisms, our approach has the following advantages: (1) neither global locking nor globally synchronized clocks are used; (2) updates can be issued at any node without synchronizing with each other; (3) updates from remote nodes are executed as they arrive, without being blocked. The access consistency and correctness of the mechanism are also discussed.     

Implementing persistent data structures using C++

Persistent data structures allow efficient access to, and modification of, previous values of the data structure. In this paper, we illustrate a class-based implementation of persistence. Our implementation provides a mechanism to transform a given (non-persistent) class to a persistent form without making any significant modifications to the class. We then demonstrate how our implementation may be used to improve the efficiency of a previously devised procedure for class testing of object-oriented software. © 1998 John Wiley & Sons, Ltd.     

GPS P码接收机本地信号发生器的FPGA实现

P码作为GPS军用伪码,具有结构复杂、周期长且码速率快的特点,这使得使用P码的软件接收机不仅定位精度高,且具有很强的抗干扰和反欺骗能力。能够实现任意卫星的任意时刻P码的产生,对于实现P码直接捕获和跟踪有很重要的意义。对于P码的产生原理和结构进行了分析,基于MATLAB设计了相应的P码发生算法并进行简单的算法仿真。之后针对FPGA硬件平台对P码发生器进行了相应的模块设计,包含寄存器模块、延时模块、周期控制模块和寄存器相位模块等。测试实验结果表明P码发生器可以基本无延迟地生成任意卫星、任意时刻的P码。     

Viewpoint determination of image by interpolation over sparse samples

We address the problem of determining the viewpoint of an image without referencing to or estimating explicitly the 3-D structure pictured in the image. Used for reference are instead a number of sample snapshots of the scene, each supplied with the associated viewpoint. By viewing image and its associated viewpoint as the input and output of a function, and the reference snapshot–viewpoint pairs as input–output samples of that function, we have a natural formulation of the problem as an interpolation one. The interpolation formulation allows imaging details like camera intrinsic parameters to be unknown, and the specification of the desired viewpoint to be not necessarily in metric terms. We describe an interpolation-based mechanism that determines the viewpoint of any given input image, which has the property that it fits all the given input–output reference samples exactly. Experimental results on benchmarking image datasets show that the mechanism is effective in reaching quality viewpoint solution even with only a few reference snapshots.     

New Compliance-Mechanism Design for Small Companion Robots

The compliance mechanisms used on robotic arms can be classified into two major categories: mechanical and electronic. The ideal characteristics of a compliance mechanism include small volume, simple mechanical structure, low cost, large complaint range, and high precision and accuracy under displacement control. Most mechanical compliance mechanisms are able to meet the first three conditions but have a small compliant range and low precision and accuracy under displacement control. The electronic compliance mechanism is hardly limited in the degree of deformation and comes with a higher precision and accuracy under the displacement control, but its sensors are expensive and the system is difficult to control. To combine the advantages of both types, this research aims to develop a new design of compliance mechanism in which a small-scale torque-limiting mechanism with a self-locking feature is installed between the actuator and the arm structure to minimize the volume while providing an ample torque limit. When the robotic arm is overloaded under an external force, a slide will occur inside the compliance mechanism so that the robotic arm will move along the direction of the external force to avoid damage. The robotic arm will automatically return to its original position after the external force is removed. The new compliance mechanism not only exceeds most of the current mechanical designs in the range of compliance but also does not affect the precision and accuracy of the displacement control. Furthermore, the new compliance mechanism does not require any sensors, which will benefit small robotic arms.     

一种针对DDoS攻击的新型防护机制研究

本文提出了一种新型的基于网络流量自相似性的DDoS防护机制,给出了该机制的体系结构,其中包括攻击检测、路径定位、特征提取、生成响应策略、实时响应、处理结束等步骤.并在此基础上,对其数据结构和工作机制进行详细的分析和设计.实验证明此方法能够较好地对DDoS攻击加以检测和防护,比传统的基于特征匹配的DDoS入侵防护方法具有较好的性能.     

Identifying frequent items in a network using gossip

We present algorithms for identifying frequently occurring items in a large distributed data set. Our algorithms use gossip as the underlying communication mechanism, and do not rely on any central control, nor on an underlying network structure, such as a spanning tree. Instead, nodes repeatedly select a random partner and exchange data with that partner. If this process continues for a (short) period of time, the desired results are computed, with probabilistic guarantees on the accuracy. Our algorithm for identifying frequent items is built by layering a novel small space “sketch” of data over a gossip-based data dissemination mechanism. We prove that the algorithm identifies the frequent items with high probability, and provides bounds on the time till convergence. To our knowledge, this is the first work on identifying frequent items using gossip.     

Distributed object model for collaborative CAD environments based on design history

This paper presents new concepts for distributed dynamic design environments that deal with three aspects not effectively considered by the design literature in an integrated way: design history, CAD data model, and virtual prototyping. The present work details a design history model that gives support to views of higher levels than those usually found in design journals of CAD systems. The dynamic nature of the distributed environment is provided by an innovative mechanism that is not dependent on CORBA's DII or any other specialized middleware structure. Moreover, this paper presents an effective integration of a geometry bus on the top of a communication layer with strong support to mutant distributed objects at run time.     

Safeguarding ad hoc networks with a self-organized membership control system

One of the key challenges for ad hoc networks is providing distributed membership control. This paper introduces a self-organized mechanism to control user access to ad hoc networks without requiring any infrastructure or a central administration entity. Our mechanism authenticates and monitors nodes with a structure that we call controller set, which is robust to the dynamic network membership. We develop analytical models for evaluating the proposal and validate them through simulations. The analysis shows that the proposed scheme is robust even to collusion attacks and provides availability up to 90% better than proposals based on threshold cryptography. The performance improvement arises mostly from the controller sets capability to recover after network partitions and from the identification and exclusion of malicious nodes.     

Problem-solving with diagrammatic representations

Diagrams are of substantial benefit to WHISPER, a computer problem-solving system, in testing the stability of a “blocks world” structure and predicting the event sequences which occur as that structure collapses. WHISPER's components include a high level reasoner which knows some qualitative aspects of Physics, a simulated parallel processing “retina” to “look at” its diagrams, and a set of re-drawing procedures for modifying these diagrams. Roughly modelled after the human eye, WHISPER's retina can fixate at any diagram location, and its resolution decreases away from its center. Diagrams enable WHISPER to work with objects of arbitrary shape, detect collisions and other motion discontinuities, discover coincidental alignments, and easily update its world model after a state change. A theoretical analysis is made of the role of diagrams interacting with a general deductive mechanism such as WHISPER's high level reasoner.