ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677817

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The concept of inheritance of object‐oriented model is important in the analysis and design of software intensive systems as a mechanism for building abstractions, for reusing structural and functional information, and for closely modeling the real world. True object‐oriented programming languages are characterized as providing features for directly implementing inheritance models. Although Ada provides features that support other characteristics of object‐oriented designs (such as information hiding, encapsulation, and modularity), it does not directly support the inheritance model and, therefore, typically is referred to as an object‐oriented language. This paper discusses the importance of incorporating the inheritance into an Ada implementation. Our approach seeks to preserve the important qualities of the inheritance model while using only the standard features of Ada without using preprocessors and specialized object‐oriented runtime environments. The approach is evaluated in terms of understandability, efficiency, support for information hiding, class construction, extensibility, and polymorphism.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677818

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper deals with the problem of plotting the robust root loci of a feedback control system which includes affine parametric uncertainties in the coefficients of the plant transfer function. First, based on a geometrical interpretation of the value set of a family of affine parametric uncertain polynomials, an efficient algorithm is proposed for checking whether the set includes the origin of the complex plane. This zero‐inclusion test algorithm is then applied along with a pivoting procedure to trace out the boundaries of the cross sections of the robust root loci. Since the proposed technique of generating a robust root locus needs not to construct all exposed edges of the value set in testing the zero inclusion condition, and needs not to use a brute‐force two‐dimensional gridding approach in plotting the boundary of a cross section of the robust root loci, its advantage of saving computational cost is obviously significant.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677819

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A window‐based token ring protocol supporting two priority traffic streams is proposed. This protocol uses the window timers to limit the packet transmissions of a token holding station. The packets arriving during a window period are always transmitted before those arriving during subsequent window periods. Nonpreemptive priority service discipline is used to serve high priority packets. A call admission control policy based on delay bound is then employed to guarantee QoS such as the packet delay, delay jitter, and the packet loss‐free requirement for both priority traffic streams. Under such window‐based token ring operation and call admission control, network‐wide fairness can be achieved and the network output traffic characteristics become predictable. With these properties, we would expect that the window‐based token protocol is more appropriate for real‐time communications.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677820

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this study, we investigated the kinetic behaviors of phosphorus release and denitrification on sludge for two biological nutrient removal (BNR) processes, i.e., suspension growth process (A2O) and combined suspension‐biofilm growth process (TNCU) under anoxic condition. The readily biodegradable substrate and nitrate loadings, 20–180 mg HAc‐COD/g MLSS and 4–25 mg NO3‐N/g MLSS respectively, are controlled in a batch reactor for phosphorus release and denitrification of sludge taken from A2O and TNCU processes under various SRT (5, 10 and 15 days) operating conditions. Experimental results indicated that the occurrence of simultaneous phosphorus release and denitrification is a kinetic competition mode under anoxic condition in the presence of a readily biodegradable substrate. Moreover, the available substrate in bulk solution determined the kinetic behaviors of phosphorus release and denitrification. To prevent nitrate inhibition, the sludge is exposed to a C/N ratio higher than 6.1 for phosphorus release. The sludge's phosphorus content (as created by different SRT processes) and initial nitrate loading dominated the kinetics of phosphorus release and denitrification, respectivley. Moreover, the sludge of suspension gorwth process demonstrated a higher phosphorus release potential than the combined suspension‐biofilm growth process. However, the nitrate inhibition is significant for A2O sludge also. Based on proposed phosphorus release rate equation, the rate constant would be reduced by denitrification about 31–67% and 20–45% for A2O and TNCU processes, respectively.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677821

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The paper applies the advanced multi‐pass dynamic programming (AMPDP) to solve the weekly hydrothermal generation coordination problem with direct load control (DLC) operation. The AMPDP technique can overcome the long calculation time and large data storage problems that the conventional dynamic programming (DP) method fails to resolve for large power systems and long scheduling period. The algorithm developed in this paper finds the optimal hydrothermal coordinated generation schedule of a power system that includes 48 thermal units and 8 hydro units with direct load control during a 192 hour study period. For the energy payback phenomenon of direct load control of air conditioner, the simulation of various energy payback patterns and various controllable capacities are presented in this paper.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677822

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In order to investigate the elastic modulus of cement‐based composite material, cylindrical specimens with different volume fractions (10%, 20%, and 30%) of aggregate are cast and tested. The effect of transition interface layer properties on the elastic behavior of cement‐based composite material was studied. The Hashin‐Shtrikman theory for evaluating the elastic modulus of two‐phase (aggregate and matrix) composite material is used as a criterion in the analysis. The Double‐Inclusion Method and Mori‐Tanaka Theory are used to predict the elastic moduli of three‐phase (aggregate, transition interface layer, and matrix) composite materials. A comparison is also made between the theoretical results and experimental data. Test results show that the influence of the transition properties on the overall elastic properties of the composite depends on the volume ratio of the aggregate. For high volume inclusion of aggregate, the composite can be considered as a three‐phase material for predicting the elastic modulus of the composite. However, low volume inclusion of aggregate, a two‐phase approach is appropriate.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677823

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper presents a novel technique for the enhancement of the operational reliability of processor arrays by a multi‐level fault‐tolerant design approach. The proposed fault tolerant architecture uses a flexible reconfiguration of redundant nodes, thereby offering a better spare utilization than existing two‐level redundancy schemes. The spare nodes at each level can replace any of the failed primary nodes, not only at the same level but also those at the lower levels. The architecture can be adopted to increase the system reliability in Multi Chip Modules (MCMs). The main contributions of our work are the higher degree of fault tolerance, higher overall reliability, higher flexibility, and a better spare utilization.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677824

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A processor array with a reconfigurable bus system (abbreviated to PARBS) is a computation model which consists of a processor array and a reconfigurable bus system. It is a very powerful computation model in that many problems can be solved efficiently. The power of a computation model usually indicates how fast a problem can be solved under that model. In [16], Wang and Chen have shown that the two‐dimensional PARBS is at least as powerful as the PRAM (parallel random access machine). That is, if a problem can be solved in O(f(n)) time on the PRAM with n processors and m memory cells, it can also be solved in O(f(n)) time on the two‐dimensional PARBS with n*m processors. The reverse assertion has not been proven yet. The difficulty arises from the great flexibility in the configurations of reconfigurable system. In this paper, we show that a restricted version of the PARBS, called ORTHOGONAL PARBS, which includes all one‐dimensional PARBS with two‐neighbor connections and many two‐dimensional PARBS with four‐neighbor connections used by some researchers, can be simulated accordingly on the SUM CRCW PRAM. That is, if a problem can be solved in O(f(n)) time on the ORTHOGONAL PARBS with n processors, it can also be solved in O(f(n)) time and O(n) memory cells on the SUM CRCW PRAM.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677825

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper presents an efficient method for the design of streamlined extrusion dies based on the prescribed strain rate variation. Both the plane strain and axisymmetric extrusions are investigated. This is vital to the preparation of the workpieces, such as bars and ingots, for many special alloys whose mechanical properties are very sensitive to the strain rate distribution during the manufacturing process. The proposed method, which incorporates the yield criterion and the velocity field with the die angularity, can give an accurate prediction of the die shape with very little computational effort. Influences of the interfacial friction and the ram velocity on the die geometry are studied. Application of this method to hydrostatic extrusion is also briefly demonstrated.

ISSN:0253-3839    

DOI:10.1080/02533839.1996.9677826

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor