A distortion-computation function D(C) is defined as the minimum expected distortion in computing some quantity-using an algorithm from a predefined set of algorithms-while using no more than C computational units. Wh...
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A distortion-computation function D(C) is defined as the minimum expected distortion in computing some quantity-using an algorithm from a predefined set of algorithms-while using no more than C computational units. When the computational problem is to encode at rate R, this gives slices of a computation-rate-distortion surface. This framework is used in the analysis of a family of JPEG coders that use output-pruned DCT calculations in place of some full DCT calculations. For encoding the Lena image at 0.5 bits/pixel, this yields a 30% reduction in complexity while lowering the PSNR by only 0.4 dB. The decoding complexity can be similarly reduced.
Variable speed electrical drives are very complex systems which makes difficult their study when detailed analysis is required along with their global behavior. With the help of advanced software tools for circuit ana...
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Variable speed electrical drives are very complex systems which makes difficult their study when detailed analysis is required along with their global behavior. With the help of advanced software tools for circuit analysis and for modeling a drive system following a modular approach, it becomes much easier to study those complex systems. This paper presents a methodology for use with Matlab/Simulink environment in which the main parts of an electrical drive are modeled as interlinked functional blocks. The complete drive system (from supply to mechanical load) is analysed as a set of independent but integrated modules.
This paper targets engineers and practitioners who want a simple procedure to compute the mean performance measures of the Batch Markovian Arrival process (BMAP/G/1) queueing system when the parameter matrices order i...
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A neu method of moment-based formulation for the solution of the telegraphist's equations in nonuniform transmission lines is presented, Entire domain basis functions that build in a frequency variation are used t...
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A neu method of moment-based formulation for the solution of the telegraphist's equations in nonuniform transmission lines is presented, Entire domain basis functions that build in a frequency variation are used to cover wider frequency and physical dimension ranges. The results obtained using the proposed formulation are validated by comparison to those obtained by a CAD package and to measured data. Different nonuniform lines in microstrip and coplanar technologies on monolithic microwave/millimeter wave integrated circuit (MMIC) and miniaturized hybrid microwave integrated circuit (MHMIC) substrates are investigated with an application to the design a matched taper transition in a MMIC coplanar line.
The problem of path tracking control for the class of articulated vehicles, in which the steering is performed by changing the articulation angle is studied. The analysis is based on the kinematics of motion, due to t...
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The problem of path tracking control for the class of articulated vehicles, in which the steering is performed by changing the articulation angle is studied. The analysis is based on the kinematics of motion, due to the fact that in the class of vehicles under study the speed of operation is relatively low and, as a result, as far as path tracking is concerned the effect of dynamics is negligible. The path tracking problem is to determine at each instant the appropriate steering action, based on the measured errors of position and orientation with respect to a desired path. Definition of these two errors, however, is rather complicated for such a vehicle. In this paper the control problem is formulated and its validity is verified through computer simulation.
This paper discusses an object-based software development and maintenance environment, Opusdei, built and used for several years at Hitachi softwareengineering (HSK - Since 1994, University of Minnesota has been invo...
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This paper discusses an object-based software development and maintenance environment, Opusdei, built and used for several years at Hitachi softwareengineering (HSK - Since 1994, University of Minnesota has been involved in the Opusdei project.) Industrial software is usually large, has many versions, undergoes frequent changes, and is developed concurrently by multiple programmers. Opusdei was designed to handle various problems inherent in such industrial environments. In Opusdei, all information needed for development is stored using an uniform representation in a central repository, and the various documentation and views of the software artifacts can be generated automatically using the tool repository. Opusdeis’ innovative capabilities are 1) uniform software artifacts representation 2) inter-relation and traceability maintenance among software artifacts 3) tools coordination and tool integration using tool composition scenarios 4) automatic documentation and versioning control. Tool coordination and composition has been discussed in the literature as a possible way to make software development environments more intelligent. Opusdei provides a uniform representation of software artifacts and tools which is an essential first step in addressing the issues of tool coordination and composition. Opusdei has been operational for several years and has been used in many large software development projects. The productivity gain reported for some of these projects, by using Opusdei ranged from 50–90%.
One of the major concerns of any maintenance organization is to understand and estimate the cost of maintenance releases of software systems. Planning the next release so as to maximize the increase in functionality a...
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ISBN:
(纸本)9780818672460
One of the major concerns of any maintenance organization is to understand and estimate the cost of maintenance releases of software systems. Planning the next release so as to maximize the increase in functionality and the improvement in quality are vital to successful maintenance management. The objective of the paper is to present the results of a case study in which an incremental approach was used to better understand the effort distribution of releases and build a predictive effort model for software maintenance releases. The study was conducted in the Flight Dynamics Division (FDD) of NASA Goddard Space Flight Center (GSFC). The paper presents three main results: (1) a predictive effort model developed for the FDD's software maintenance release process, (2) measurement-based lessons learned about the maintenance process in the FDD, (3) a set of lessons learned about the establishment of a measurement-based software maintenance improvement program. In addition, this study provides insights and guidelines for obtaining similar results in other maintenance organizations.
Views are an established technique for restructuring and repartitioning the format of data, classes, and schemata so that applications can customize shared data objects without affecting other applications' percep...
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