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Assessing and understanding efficiency and success of software production

Empirical Software Engineering 2000年第2期5卷 125-154页

作者： Von Mayrhauser, A. Wohlin, C. Ohlsson, M.C. Computer Science Department Colorado State University Fort Collins CO 80523 United States Dept. of Communication Systems Lund University Box 118 SE-221 00 Lund Sweden

One of the goals of collecting project data during software development and evolution is to assess how well the project did and what should be done to improve in the future. With the wide range of data often collected and the many complicated relationships between them, this is not always easy. This paper suggests to use production models (Data Envelope Analysis) to analyze objective variables and their impact on efficiency. To understand the effect of subjective variables, it is suggested to apply principal component analysis (PCA). Further, we propose to combine the results from the production models and the analysis of the subjective variables. We show capabilities of production models and illustrate how production models can be combined with other approaches to allow for assessing and hence understanding software project data. The approach is illustrated on a data set consisting of 46 software projects from the NASA-SEL database (NASA-SEL, 1992). The data analyzed is of the type that is commonly found in project databases.

关键词： Software engineering

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Call admission and control scheme for quality-of-service (QoS) provisioning in next generation wireless networks

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Wireless networks 2000年第1期6卷 17-30页

作者： Das, Sajal K. Jayaram, Rajeev Kakani, Naveen K. Sen, Sanjoy K. Ctr. Res. Wireless Mobility N. Dept. of Comp. Sci. and Engineering University of Texas at Arlington Arlington TX 76019 United States TDMA Systems Ericsson Inc. 740 E Campbell Road Richardson TX 75081 United States Department of Computer Science University of North Texas Denton TX 76203-1366 United States Adv. Wireless Networks Technology Nortel Networks 2201 Lakeside Boulevard Richardson TX 75082 United States Indian Institute of Science Bangalore India University of Central Florida Orlando FL United States Dept. of Comp. Sci. and Eng. Ctr. Res. Wireless Mobility N. University of Texas Arlington TX United States University of North Texas Denton TX United States Council of National Research Pisa Italy Slovak Academy of Sciences Bratislava Slovakia Indian Statistical Institute Calcutta India Ericsson Inc. Richardson TX United States Northern Telecom Richardson TX United States

We propose a framework for quality-of-service (QoS) provisioning for multimedia services in next generation wireless access networks. This framework aims at providing a differentiated treatment to multimedia traffic flows at the link layer, which can be broadly classified as real-time (or delay-sensitive) and non-real-time (or delay-tolerant). Various novel schemes are proposed to support the differential treatment and guarantee QoS. These schemes include bandwidth compaction, channel reservation and degradation, with the help of which a call admission and control algorithm is developed. The performance of the proposed framework is captured through analytical modeling and simulation experiments. Analytically, the average carried traffic and the worst case buffer requirements for real-time and non-real-time calls are estimated. Simulation results show up to 21% improvement in the admission probability of real-time calls and up to 17% improvement in the admission probability of non-real-time calls, when various call control techniques like bandwidth compaction are employed. Using our channel reservation technique, we observe a 12% improvement in the call admission probability compared to another scheme proposed in the literature.

关键词： Wireless telecommunication systems

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A wireless ATM MAC protocol with combined hybrid ARQ and adaptive scheduling

A wireless ATM MAC protocol with combined hybrid ARQ and ada...

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IEEE VTS 50th Vehicular Technology Conference, VTC 1999-Fall

作者： Huang, Hui Tsang, Danny H.K. Ko, Tsz-Mei Kuehn, Paul J. Dept. of Electrical and Electronic Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Institute of Communication Networks and Computer Eng. University of Stuttgart Stuttgart Germany

ISBN: (纸本)0780354354

A combined hybrid ARQ error control and adaptive scheduling scheme is proposed for TDMA/TDD MAC protocols in wireless ATM networks. Type-II hybrid ARQ is chosen as the error recovery scheme, while adaptive fair-queueing is designed to achieve a fair and efficient resource allocation. In particular, the weight of a connection used in the fair-queueing algorithm is dynamically adjusted according to the varying channel conditions and the types of services. Simulation results show that the proposed scheme can achieve better throughput and transfer reliability with minimized delay and cell loss rate when compared with the conventional MAC layer control. © 1999 IEEE.

关键词： Time division multiple access

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A method for sharing interactive deformations in collaborative 3D modeling 99

A method for sharing interactive deformations in collaborati...

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Proceedings of the ACM symposium on Virtual reality software and technology

作者： Hiroaki Nishino Kouichi Utsumiya Kazuyoshi Korida Atsunori Sakamoto Kazuyuki Yoshida Dept. of Computer Science and Intelligent Systems Oita University Oita 870-1192 Japan Dept. of Communication Oita Pref. College of Arts and Culture Oita 870-0833 Japan

ISBN: (纸本)9781581131413

This paper proposes a new approach to collaboratively designing original products and crafted objects in a distributed virtual environment. Special attention is paid to concept formulation and image substantiation in the early design stage. A data management strategy and its implementation method are shown to effectively share and visualize a series of shape-forming and modeling operations performed by experts on a network. A 3D object representation technique is devised to manage frequently updated geometrical information by exchanging only a small amount of data among participating systems. Additionally, we contrive a method for offloading some expensive functions usually performed on a server such as multi-resolution data management and adaptive data transmission control. Client systems are delegated to execute these functions and achieve “interactivity vs. image quality” tradeoffs based on available resources and operations in a flexible and parallel fashion.

关键词： collaborative design computer graphics 3D object modeling distributed virtual environment

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Real-time Path Planning for Intelligent Robots System Based on Vision Information

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IFAC Proceedings Volumes 1999年第2期32卷 861-866页

作者： Qingchun Meng Changjiu Zhou K. Jagannathan K.S. Leong Hongbo Ji Department of Electronics & Communication Engineering of Singapore Polytechnic 139651 Tel: 65 7721440 Fax: 65 7721974. Singapore Computer Science Dept. of Yantai University 264005 Yantai China State Key Lab. of Intelligent Technology & Systems of Tsinghua University 100084 Beijing China

Real-time path planning is a key subject in the research of a Multi-robot system, such as in soccer robot system, as in such system there are several robots to coordinate to complete one task and its workspace is time-varying. There exist unpredictable changes in such workspace. These changes will make the robots path planning tremendously hard. This paper introduce the study on the real-time planning of a multi-robot system, such as soccer robots system. In such systems, as there exist multiple mobile robots, robots path planning is highly required of real-time and of high path planning quality. In this paper, the definitions of Active Obstacle and Dominating Robot are put forward. Genetic-planning and Fuzzy-correction are developed as our path planning techniques. The concept of Sector Vital Value is proposed for Genetic-planning and Fuzzy-correction. Block-Inserting strategy is employed to further improve the system's real-time performance in the workspace modelization. It takes only 2% of workspace modeling time required by Grid-modeling technique. After taking the proposed measures, the system's real-time performance is improved a lot. The initial simulation shows that our planning strategy can meet real-time demand.

关键词： Multi-agent System Path Planning Fuzzy Logic Genetic Algorithms

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3D object modeling using spatial and pictographic gestures 98

3D object modeling using spatial and pictographic gestures

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ACM Symposium on Virtual Reality Software and Technology, VRST 1998

作者： Nishino, Hiroaki Utsumiya, Kouichi Korida, Kazuyoshi Dept. of Computer Science and Intelligent Systems Oita University Oita 870-1192 Japan Dept. of Communication Oita Pref. College of Arts and Culture Oita 870-0833 Japan

ISBN: (纸本)1581130198

While many sophisticated 3D rendering methods are available to produce realistic output, 3D data input still is a tedious and time-consuming task. This paper proposes a new method for modeling 3D objects using hand gestures. First of all, a conceptual model, the so-called "image externalization loop" model, is introduced as a framework to realize an efficient 3D object creation environment. Then, a 3D shape forming method for implementing the model is described in detail. Two-handed spatial and pictographic gestures are used to describe the features of the object in shape, size and deformation pattern. The implicit superquadric functions apply to build a deformable 3D model with blending and axial deformations as their extensions. A generic hand gesture learning and recognition facility is developed and used to translate the gestures into specific superquadrics parameters to deform the object. Finally, some experimental results are shown to express the capability and usefulness of the proposed method with its potential application areas. © 1998 ACM.

关键词： Virtual reality

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Distance Learning: Is It the End of Education as Most of Us Know It? 98

Distance Learning: Is It the End of Education as Most of Us ...

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1998 ACM Conference on Human Factors and Computing systems, CHI 1998

作者： Laurillard, Diana Preece, Jenny Shneiderman, Ben Neal, Lisa Warn, Yvonne Pro-Vice-Chancellor Technology Development Open University Milton KeynesMK7 6AA United Kingdom Information Systems Department University of Maryland Baltimore County BaltimoreMD21250 United States Department of Computer Science University of Maryland College ParkMD20742 United States EDS 3 Valley Road LexingtonMA02173 United States Dept. of Communication Studies Linkoping University Sweden

ISBN: (纸本)1581130287

The purpose of this panel is to present and discuss the key issues in distance learning from different perspectives and to envision future directions. The different views of the panelists include: professionals vs. students;large classes vs. small;distance learning university vs. introduced within regular university or as part of a class;and different cultural perspectives. © 1998. Copyright on this material is held by the author.

关键词： Distance education

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Application of artificial neural networks to historical data analysis for short-term electric load forecasting

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EUROPEAN TRANSACTIONS ON ELECTRICAL POWER 1997年第1期7卷 49-56页

作者： Caciotta, M Lamedica, R Cencelli, VO Prudenzi, A Sforna, M Maurizio Caciotta (1945) has been Associate Professor of Electrotechnical Elements at Calabria University Italy. since 1978. Then hejoincd the University of Rome “La Sapienza” Italy. where he has been Associate Professor of Electrical Measurements since 1985. Since I99 1 he has been Associate Professor at the Third University of Rome. His main interests= in the field ofparallel computing and of neural network applications to information processing and data analysis. (Dept. of Electronic Engineering Terza Universitl di Roma. Via C. Segre 2. 1-00146 Romdltaly Tel +396/5599 779. Fax +396/5561373) Regina Lamedica (1952) received the doctor degree in Electrical Engineering from the University of Bologna. Italy. in 1976. She has joined the University of Rome “La Sapienza” where she has been Assistant Professor in Electric Power Systems since 1978 and Associate Professor in Electric Power Systems for Tnnsponation since 1987. Her main interests are in computer applications to Electrified Transportation Systems and to Power Systems analysis. She is a member of ClFI (Italian Railway Engineers Association) and of AEI (Italian Electrical Association). (Dept. of Electrical Engineering. University of Rome “La Sapienza” Via Eudossiana 18 1-00184 Romdltaly. Tel +396/44585808 Fax + 39614 88 32 35) Valentino Orsolini Cencelli (1963) received the degree in Electronic Engineering from the University of Rome “LaSapienza”. Since 1992hejoined the Third University of Rome where he is a Ph.D. student. His main interest are in parallel computing and in neunl networks applications to Measurement Science. (Dept. of Electronic En ' oineerinp. Terza Universiti di Roma Via C. Segre2 I-00146Roma/ltaly Tel+396/5599779 Fax++396/5561 373) Alberto Prudenzi (1961) received the degree and the Ph.D. degree in Electrical Engineering from the University of Rome “La Sapienza” respectively in I987 and 1993. In I988 he joined Dept. of Electrical Engineering of the University of Rome where since 1992 he has been Assistant Professor in Electrica

The paper illustrates two different Artificial Neural networks (ANN) architectures for electric Short-Term Load Forecasting (STLF). Two multi-layer perceptron ANN using the back-propagation learning algorithm have been implemented which provide different, although complementary, forecasting approaches (static and dynamic). In order to test the potentialities of the architectures implemented, the ANN have been applied to the Short-Term Forecasting of Italian hourly electric load. The importance of this load (peak demands up to about 38 000 MW) requires tools for STLF which must be as more accurate and precise as possible. This fact has imposed the adoption of some algorithmic enhancements to the basic back-propagation algorithm formulation. Since an adequate formulation of the influence exerted on hourly electric load by the main meteorological and climatic factors is nor known at present, the data set used for ANN training phase has concerned only historical series of electric hourly demand. The paper illustrates the two ANN architectures as well as the computational platforms used for implementation, Finally, some results obtained from the application of the two ANN to the short-term forecasting of Italian electric load relevant to three different weeks of the year 1993 are comparatively reported.

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A noise reduction method for chaotic time series

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ELECTRONICS AND communicationS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC science 1996年第12期79卷 91-100页

作者： Itoh, KI NTT Communication Science Laboratories Yokosuka Japan 238-03 Ken-icbi Itoh graduated in 1969 from the Dept. Electrical Eng. Kyushu Inst. Tech. and affiliated with NlT. He is engaged in R&D of computer hardware systems. Recently he has been engaged in research on application of chaos. At present Senior Research Engineer Supervisor NTT Comm. Sci. Lab. He is a member of Inf. Proc. SOC.

Intensive studies have recently been made on the noise reduction method for the chaotic time series. In those approaches, the trajectory of the attractor is reconstructed in the multidimensional space from the single-variable time-series data, and then the deviation of the trajectory is corrected. In the conventional method, the noise is assumed to be Gaussian distribution. Consequently, when the outliers are contained in the real data, they are difficult to delete. This paper intends to solve this problem and proposes a noise reduction method for the chaotic time-series data, considering not only the noise with the Gaussian distribution, but also the outliers. A method is devised that eliminates the outliers efficiently using Biweight estimation and similar methods, and a program is constructed based on the idea. The experimental data are constructed by adding the pseudorandom variable with the Cauchy or Gaussian distribution to the chaotic time-series data generated from the Henon map and the Lorenz model. Using these data, the noise reduction experiment is conducted;the relative error, the phase plot and correlation dimension are examined. It is verified as a result that the proposed method can reduce drastically the effect of the outliers compared to the conventional methods, and has nearly the same noise reduction performance as in the conventional methods for the noise with the Gaussian distribution.

关键词： chaos noise reduction time-series data outlier

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Proof Method for correctness of refinements of algebraic specification in abstract sequential machine style

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systems AND computerS IN JAPAN 1996年第5期27卷 25-38页

作者： Okano, K Higashino, T Taniguchi, K Member Faculty of Engineering Science Osaka University Toyonaka Japan 560 Teruo Hipshino received his B.E. M.E.and Ph.D. degrees in Information and Computer Sciences from Osaka University Osaka Japan in 1R9 1981 and 1984 respectively. He joined the Faculty of Osaka University in 1984. Since 1991 he has been an Associate Professor in the Department of Information and Computer Sciences at Osaka University. In 1990 he was a Visiting Researcher of Dept. I.R.O. at University of Montreal Canada. His current research interests include design and analysis of distributed systems specification and verification of communication protocols and formal approach of program design. He is a member of IEEE-CS ACM IEICE of Japan and IPS of Japan.

In this paper, new methods for providing the correctness of refinement among abstract sequential machine style programs are described. The programs are described in algebraic language ASL using some useful notions, i.e., the extended projection and the valid reachability condition for each transition function. These notions allow a designer to refine a given text (program or specification) to a concrete text more freely than the text that does not use such notions. These notions can also enhance the expressive power of the text. On the other hand, these advantages would have lost half their values, if useful methods to prove the correctness of refinement among the texts using them are not found. Thus new methods for proving the correctness of the texts are proposed, and they do not require much proof loads. First, the correctness of refinement among the ASL texts with the extended projection is defined. Second, a method is proposed for proving the correctness of refinement among such texts. Also proposed is a definition of the correctness of refinement among the texts with the valid reachability conditions and a method to prove their correctness. These methods do not require more proof loads than the usual methods for the texts that do not use such notions in the abstract sequential machine style. Therefore, these methods are useful.

关键词： abstract sequential machine ASL language proof algebraic specification

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