A variety of specification languages exist that support one or more phases of software development. This article emphasizes languages that support the functional phase, i.e., languages that can be used to define the o...
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A variety of specification languages exist that support one or more phases of software development. This article emphasizes languages that support the functional phase, i.e., languages that can be used to define the observable behavior of a system. The languages surveyed include Z, Prolog, SF, Clear, Larch, PAISLey, Spec, CSP, SEGRAS and BagL. The article divides the languages into four major categories based on the way the language specifies the external behavior of the system and on the ability of the language to specify concurrent systems. Each language section includes a discussion of the constructs of the language, a specification of a problem in the language, and an evaluation of the language. The article is intended to acquaint the reader with a wide range of functional specification languages.
The aliasing probabilities of multiple-input signature registers (MISR) with m inputs for a 2/sup m/-ary symmetric channel, where each of the (2/sup m/-1) possible errors is equally likely, are analyzed. For this erro...
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The aliasing probabilities of multiple-input signature registers (MISR) with m inputs for a 2/sup m/-ary symmetric channel, where each of the (2/sup m/-1) possible errors is equally likely, are analyzed. For this error model, the aliasing probabilities of MISRs are analyzed using the weight distributions of maximum-distance-separable (MDS) codes. The results show that the aliasing probabilities over the 2/sup m/-ary symmetric channel do not depend on the polynomials that characterize the MISRs. That is, for the 2/sup m/-ary symmetric channel, the aliasing probability of an MISR based on a primitive polynomial is exactly the same as one based on a nonprimitive one. In addition, it is observed that the aliasing probabilities, P/sub al/ (n), as a function of test length n, are monotonous for error probabilities p=0.2, 0.4, and 0.8. The aliasing probabilities of multiple MISRs based on Reed-Solomon codes are analyzed again for the 2/sup m/-ary symmetric channel, using the weight distributions of Reed-Solomon codes, which are MDS codes.< >
We analyze, for mobile users in regular cellular arrays, the probability that a call is blocked from accessing a channel (when originating or when attempting to hand off during an active user's sojourn). This prob...
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We analyze, for mobile users in regular cellular arrays, the probability that a call is blocked from accessing a channel (when originating or when attempting to hand off during an active user's sojourn). This probability, p, is studied here as a function of the originating call load, in Erlangs per cell, with the number of channels and user mobility treated as parameters. Using simulation, we demonstrate that a simple ad hoc Erlang-B formula, based on an equivalent traffic load, gives an excellent approximation to p. The approximation is good regardless of the nature of the user motion or whether the cellular arrays are linear or planar. By the ''cost of mobility,'' we mean the additional channels (in percent) that are needed to meet a required p because the user is mobile. Using the ad hoc formula, we show that the cost of mobility is generally minor, becoming appreciable only for high mobility coupled with low traffic loads. Two of the high-mobility examples consider 105-kmph user movement with only 200 m traversed per cell. Calls are assumed to have a one-minute mean holding time, and the value of p is required to be 1%. For a traffic load of 50 Erlangs per cell, about 10% more channels are needed with mobility than when there is no mobility. In the second example, with only 3 Erlangs per cell, the extra channels needed increase to 25%.
Too often, software developers depend on heuristic debugging efforts during final integration to catch and correct software errors. Test tools for software allow developers to perform more systematic and thorough soft...
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Too often, software developers depend on heuristic debugging efforts during final integration to catch and correct software errors. Test tools for software allow developers to perform more systematic and thorough software testing early in the development cycle.
CASE tools are complex software products offering many different features. Systems professionals evaluated various CASE products from a feature and attribute basis. Each product has a different mix of strengths and we...
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CASE tools are complex software products offering many different features. Systems professionals evaluated various CASE products from a feature and attribute basis. Each product has a different mix of strengths and weaknesses as perceived by the end user. Specific CASE tools support different steps of the applications development process as well as varying methodologies. The complexity of software development, diversity of tools and features leads to several questions. What CASE features are being used by systems developers? What areas of CASE tolls need improvement? Are some CASE tools or product attributes considered to be better than others? (C) 1998 Elsevier Science Inc. All rights reserved.
This work focuses on some peculiarities of 2-D group delay equalization by means of cascades of 2 x 2 sections, a 2-D equalization technique that has lately received considerable attention. It appears that the group d...
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This work focuses on some peculiarities of 2-D group delay equalization by means of cascades of 2 x 2 sections, a 2-D equalization technique that has lately received considerable attention. It appears that the group delay performance obtained by just one or two 2 x 2 sections equalizers cannot be significantly improved by using equalizers with a greater number of sections. As a consequence, group delay errors of the same magnitude orders of those obtained in the 1-D case can rarely been obtained with this technique. The work evidences how the characteristics and the possibilities of 2-D group delay equalization (far from being completely known) markedly differ from those of the 1-D case.
In a previous study, Ohtera and Yamada (1990) formulated and solved two resource allocation problems for software-module testing, considering only the mean number of remaining faults in the software modules. When soft...
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In a previous study, Ohtera and Yamada (1990) formulated and solved two resource allocation problems for software-module testing, considering only the mean number of remaining faults in the software modules. When software-module testing is completed, the actual number of remaining faults may turn out to be much larger than the mean. It is, therefore, important to reduce the variance of the number of remaining faults. In this paper, we study a dynamic resource allocation strategy for software module testing. This strategy takes into account the variations of the number of detected faults during testing, re-estimates the model parameters using all the available fault detection data and dynamically allocates the testing resources to the software modules. The simulation results show that this strategy can effectively reduce the variance of the number of remaining faults. (C) 1997 by Elsevier Science Inc.
A case study to test the feasibility of measuring output from university research has been performed at Chalmers University of Technology based on five categories: graduate degrees awarded, scientific publications, ci...
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A case study to test the feasibility of measuring output from university research has been performed at Chalmers University of Technology based on five categories: graduate degrees awarded, scientific publications, citations, patents, and spin-off companies. These outputs have been subjectively combined into a merit figure and compared to inputs in the form of department budgets and other outputs such as the teaching load. Regression analysis with the budget allocated with a peer review have been made. Cost estimates for the measurement method are presented. The method has also been compared to a peer review method
Enumeration and traceability software tools are used for enhancing in-process management and quality in system and product development in different industries, such as telecommunications and aerospace. toots are used ...
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Enumeration and traceability software tools are used for enhancing in-process management and quality in system and product development in different industries, such as telecommunications and aerospace. toots are used for managing the entities-system requirements, architecture descriptions, physical/logic designs, modules of source code, or test cases-of any hardware/software systems. Enumeration is a process for enclosing, labeling and numbering individual entities for further linking or referring to the related entities in one-to-one, one-to-many, and many-to-many relationships. The entity dependencies in a set of documents determine the overall parent-child relationships of entities for specifying a system or a product. Traceability is a tracking and bookkeeping process for evolution and interaction of the individual entities in a system's or product's life cycle. The mechanism built by these two processes are for the functionality similar to hypertext mechanism for document browsing. However, these tools also provide forward-backward tracking for all linked entities, display the overall dependency in a form of a binary tree and perform bookkeeping on the entity changes. In the heterogeneous computing environments, these enumeration and traceability tools are built as add-on applications on the existing document authoring toots or editors for use in networking environment. For example, using a traceability tool with a messaging tool, e.g., e-mail, the project team members can work together as in a groupware and communicate timely about entity update information with other team members who own the impacted entities. In this paper, we present an enumeration and traceability tool (Radix) for use in two popular networking environments, UNIX and WINDOWS environments, with examples. This tool is currently used in AT&T service and product development organizations. (C) 1997 Elsevier Science Inc.
The generation of long-wavelength Gortler vortices is studied in the linear regime by numerically solving the time-dependent governing equations. It is found that time-dependent surface deformations, which assume a fi...
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The generation of long-wavelength Gortler vortices is studied in the linear regime by numerically solving the time-dependent governing equations. It is found that time-dependent surface deformations, which assume a fixed non-zero shape at large times, generate steady Gortler vortices that amplify in the downstream direction. Thus, the Gortler instability in this regime is shown to be convective in nature, contrary to the earlier findings of Ruban and Savenkov. The disturbance pattern created by steady and streamwise-elongated surface obstacles on a concave surface is also examined in detail and contrasted with the flow pattern on a flat surface, due to roughness elements with an aspect ratio of order unity. Some difficulties in applying the Briggs-Bers criterion to unstable physical systems of this type are pointed out.
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