Matrix filtering as an aid to numerical integration

Digital simulation of linear systems often is complicated by the simultaneous presence of "slow" and "fast" time constants (or of small and large eigenvalues). A procedure is described that simplifies the treatment of such systems. Roughly speaking, the procedure consists of separating the response into a "low-frequency" and a "high-frequency" component, calculating each component, and then adding the results. The response separation is effected by using elementary Filter Theory ideas in a matrix context. Exact eigenvalue information is not required; a rough idea of eigenvalue locations is needed, however, to effect the responce separation.     

ISDN as an enabler for enterprise integration

Integrating an enterprise is defined as making the various parts of the business work closely together in harmonious and timely support of its goals. Four aspects of enterprise integration are described and discussed: an executive cockpit through which top executives can obtain timely, vital information about their business, wherever they are; concurrent engineering, with customer and supplier participation; interoffice interaction; and computer-integrated manufacturing, both intersite and intercompany. User requirements and the integrated services digital network (ISDN) technical solution(s) being developed in order to achieve these aspects of enterprise integration are examined     

Lightning-flash counter as an aid to the measurement of radio noise from thunderstorms

Records from lightning-flash counters, coupled with a knowledge of the energy radiated by a typical discharge, enable the expected radio noise from local thunderstorms to be calculated. Comparisons with the results of direct noise measurements in Singapore suggest that these may be in error at medium frequencies under some storm conditions.     

Automated pseudo-live testing of firewall configuration enforcement

Network security devices such as firewalls and intrusion detection systems are constantly updated in their implementation to accommodate new features, performance standards and to utilize new hardware optimization. Reliable, yet practical, testing techniques for validating the configuration enforcement after every new software and firmware update become necessary to assure correct configuration realization. Generating random traffic to test the firewall configuration enforcement is not only inaccurate but also impractical as it requires an infeasible number of test cases for a reasonable testing coverage. In addition, in most cases the policies used during testing are manually generated or have limited configuration profiles. We present a framework for automatic testing of the firewall configuration enforcement using efficient and flexible policy and traffic generation. In a typical test session, a large set of different policies are generated based on the access-control list (ACL) grammar and according to custom profiles. Test packets are generated to particularly consider critical segments of the tested policies and to achieve high coverage of the testing space. We also describe our implementation of a fully-automated framework, which includes ACL grammar modeling, the policy generation, test cases generation, capturing and analyzing firewall output, and creating detailed test reports. Our evaluation results show that our security configuration testing is not only achievable but it also offers high coverage with significant degree of confidence.     

Efficient object-oriented integration and regression testing

This paper presents a model, a strategy and a methodology for planning integration and regression testing from an object-oriented model. It shows how to produce a model of structural system test dependencies which evolves with the refinement process of the object-oriented design. The model (test dependency graph) serves as a basis for ordering classes and methods to be tested for regression and integration purposes (minimization of test stubs). The mapping from unified modeling language to the defined model is detailed as well as the test methodology. While the complexity of optimal stub minimization is exponential with the size of the model, an algorithm is given that: computes a strategy for integration testing with a quadratic complexity in the worst case; and provides an efficient testing order for minimizing the number of stubs. Various integration strategies are compared with the optimized algorithm (a real-world case study illustrates this comparison). The results of the experiment seem to give nearly optimal stubs with a low cost despite the exponential complexity of getting optimal stubs. As being a part of a design-for-testability approach, the presented methodology also leads to the early repartition of testing resources during system integration for reducing integration duration     

浅析集成测试和系统测试的关系

软件测试过程划分为单元测试、集成测试、确认测试、系统测试、验收测试五个阶段,其中集成测试和系统测试是对整个系统或者子系统的功能等特征进行的测试,所采用的测试方法相对复杂,文本分析了它们之间的联系和区别.     

Automated double-frequency testing technique for mapping receiveinterference responses

This paper presents the basic principles of a double-frequency testing technique for highly informative visualization of the linear and nonlinear interference responses of receivers. The technique is implemented with an automated double-frequency test system (DFTS) built around conventional controlling and measuring equipment. The main advantages of DPTS are gained by using the principles of raster-like changing of test signals frequencies combined with visualization of test results as two-dimensional (2-D) raster images of the receiver-under-test double-frequency diagrams (or interference response maps). Basic functionalities of the technique for double-frequency testing, which make possible automated detection and identification of all types of interference in the receiver and measurement of their parameter's, are described. Results of practical implementation of this technique for testing super-high frequency (SHF) receivers, RF amplifiers (RFA) and diode generator are discussed     

Characteristics of motorist aid communications systems

The nature and magnitude of the demand for emergency communications generated by users of rural freeways is described. A classification diagram of potential communications systems is presented and a preliminary selection of candidate systems is made on the basis of overall technical and economic considerations. The operating efficiency of the selected systems is analyzed in terms of their estimated detection efficiency and detection time performance. This analysis when combined with system cost projections demonstrates that a one-mile interval terminal design providing two-way voice communication between the motorist and an aid dispatch center provides the best benefit-cost ratio consistent with a satisfactory level of service. The operational characteristics of the selected system are described in some detail.     

Automated placement of testing pads for electron-beam observation

A novel testing-pad placement method has been developed to greatly improve the electron-beam testing observability of multi-metal-layer LSIs. The pads consist of such small stacked vias that they can be placed in any unoccupied area of an LSI layout without any change in chip size. The observability is more than 88% for a 0.25um 390kG ASIC with this method.     

A novel large-memory neural network as an aid in medical diagnosisapplications

Describes the application of a LAMSTAR (LArge Memory STorage And Retrieval) neural network to medical diagnosis and medical information retrieval problems. The network is based on M.L. Minsky's (1980) knowledge lines (k-lines) theory of memory storage and retrieval in the central nervous system. It employs arrays of self-organized map modules, such that the k-lines are implemented via link weights (address correlation) that are updated by learning. The network also employs features of forgetting and of interpolation and extrapolation, and is thus able to handle incomplete data sets. It can deal equally well with exact and fuzzy information, thus making it specifically applicable to medical diagnosis where the diagnosis is based on exact data, fuzzy patient interview information, patient histories, observed images and test records. Furthermore, the network can be operated in a closed loop with search engines to intelligently use data from the Internet in a higher learning hierarchy. All of the above features are shown to make the LAMSTAR network suitable for medical diagnosis problems that concern large data sets of many categories that are often incomplete and fuzzy. Applications of the network to three specific medical diagnosis problems are described: two from nephrology and one related to an emergency-room drug identification problem. It is shown that the LAMSTAR network is hundreds, and even thousands, times faster in its training than backpropagation-based networks when used for the same problem with exactly the same information     

Rapid integration and testing of business solutions

Rapid application development (RAD) methodology is increasingly being used by software development units across BT as a means of delivering maximum functionality in the shortest time thereby allowing the company to respond quickly to new business opportunities. DSDM (Dynamic Systems Development Method) has emerged as the UK and international standard for RAD and is currently being used by a number of development units within BT. For a number of reasons, some of the fundamental tenets of DSDM are proving difficult to use for small to medium size multimedia and business solution projects. This paper looks at how the Advanced Service Management Unit of BT's Systems Integration Department has responded to this situation and formulated a hybrid approach to testing known as SI-Rapid.     

The Viterbi algorithm as an aid in text recognition (Corresp.)

The results of an experiment are described in which contextual information is used to improve the performance of an optical character reader when reading English text. Specifically, English is modeled as a Markov source and the Viterbi algorithm is used to do maximuma posteriorisequence estimation on the output of an optical character reader (OCR).     

ARCHGEN: Automated synthesis of analog systems

High-level design of analog systems is an open area that needs to be addressed with the emerging trend of integrating mixed analog-digital systems. Design methods compatible across the analog-digital boundaries would expedite the design process, and in this paper we address analog high-level design issues. An approach for systems-level synthesis of a class of analog systems is presented. A behavioral level for the analog domain is characterized in terms of state equations and transfer functions in the continuous and discrete domains. State-space representations are generated from transfer function specifications that exhibit system level characteristics such as controllability and observability as, well as decoupled and parallel architectures. These state-space representations are synthesized into behavioral-level, technology-independent architectures composed of analog functional components. An intermediate architecture in a circuit implementation technology is synthesized from the behavioral architecture. The various algorithmic procedures for synthesis are implemented in the program ARCHGEN. Behavioral simulation is used for architecture verification and design space exploration     

Model-driven systems development and integration environment

Telecommunications operators are undergoing massive transformations in order to metamorphose themselves into the ICT world and compete with agile, lean IT organisations. The main challenges facing telecommunications operators, such as BT, are to reduce costs and increase agility in deploying software systems for provisioning ICT services. Despite using reusable capabilities and COTS packages, the major source of increased cost lies in the heavy integration tax we incur for integrating diverse systems implemented on diverse platforms and middleware, with heterogeneous data and process models. This paper looks at cost implications of lengthy and often manual migration to-and-from systems and platforms, and shows the clear business benefits of model-driven development (MDD) as defined by the Object Management Group (OMG). It is clearly demonstrated that model-driven development has matured into a practical, industrialised, scalable and evolvable technology, culminating from decades of R&D on specification and design languages, executable formalisms and domainspecific languages and language transformations.     

Sequential testing of sorted and transformed data as an efficient way to implement long GLRTs

It is often required to detect a long weak signal in Gaussian noise, and frequently, the exact form of that signal is parameterized but not known. A bank of matched filters provides an appropriate detector. However, in some practical applications, there are very many matched filters, and most are quite long. The consequent computational needs may render the classical bank-of-filters approach infeasibly expensive. One example, and our original motivation, is the detection of chirp gravitational waves by an Earth-based interferometer. In this paper, we provide a computational approach to this problem via sequential testing. Since the sequential tests to be used are not for constant signals, we develop the theory in terms of average sample number (ASN) for this case. Specifically, we propose two easily calculable expressions for the ASN: one a bound and the other an approximation. The sequential approach does yield moderate computational savings, but we find that by preprocessing the data using short/medium fast Fourier transforms (FFTs) and an appropriate sorting of these FFT outputs such that the most informative samples are entered to a sequential test first, quite high numerical efficiency can be realized. The idea is simple but appears to be quite successful: Examples are presented in which the computational load is reduced by several orders of magnitude. The FFT is an example of an energy-agglomerating transform, but of course, there are many others. The point here is that the transform need not match the sought signal exactly in the sense that all energy becomes confined to a single sample; it is enough that the energy becomes concentrated, and the more concentrated the better.     

Automated repair of complex systems by fault compensation

A formal method used to repair discrete-event systems consisting of communicating processes is described. Two mechanisms of repairing faulty systems are proposed: the first inserts a new “compensator module” into the communication channel between the faulty process and one or more of its neighbors; the second modifies a neighbor of the faulty process in a compensating manner. The two mechanisms fall under a class of methods in which faults are not fixed by replacement of a faulty unit with a fault-free one, but where changes to the non-faulty parts of the system repair the system. A finite-state model is used to describe processes, and the problem is solved for two models of communication: the symmetric (or the handshake) model and, an asymmetric model. The algorithm is described, and examples are presented, including an indication of how the approach may be applied as part of a sophisticated fault management system for communication networks     

一种可实现高速信号处理的超声波无损检测系统的设计

无损探伤技术是在不损坏工件或原材料工作状态的前提下,对被检验部件的表面和内部质量进行检查的一种测试手段.超声波探伤就是利用超声能透入金属材料的深处,并由一截面进入另一截面时,在界面边缘发生反射的特点来检查零件缺陷的一种方法.     

Flow lines on the poincaré sphere as an aid to the study of mode polarization in lasers

It is shown that the concept of flow lines on the Poincaré sphere is a useful tool in the study of mode polarization in lasers. As an example, a case from recent literature is analyzed.