the QFN (quad flat non-leaded) package is a new type of chip scale package. In this study, boththe FEM solid model and CFD model of QFN package were generated to predict the junction-to-ambient thermal resistance of ...
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the QFN (quad flat non-leaded) package is a new type of chip scale package. In this study, boththe FEM solid model and CFD model of QFN package were generated to predict the junction-to-ambient thermal resistance of the package under natural and forced convection. the solid model uses flat plate surface convection correlations to simulate the package and board cooling. the CFD model uses computational fluid dynamics software to simulate surface convective loads. In comparison with experimental measurements, the results show that the CFD model is more accurate than the solid model to predict the thermal resistance of the package. the convection heat transfer coefficients obtained from CFD model were also applied to the surface correlations of FEM solid model. It shows that the accuracy of simulation results by FEM solid model can be improved withthe surface convection correlations of CFD results. Furthermore, the distribution of heat transfer over external faces of the package is calculated. the results show that most of the heat is dissipated to the board through the bottom surface of the lead frame.
Nowadays, several approaches for developing web applications have been proposed in the literature. Most of them extend existing object-oriented conceptual modeling methods, incorporating new constructors in order to m...
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ISBN:
(纸本)0769519873
Nowadays, several approaches for developing web applications have been proposed in the literature. Most of them extend existing object-oriented conceptual modeling methods, incorporating new constructors in order to model the navigational structure and the content of web applications. Such new constructors are commonly represented in a Navigational Model. While navigational models constitute the backbone of web application design, their quality has a great impact on the quality of the final product which is actually implemented and delivered. In this paper, we discuss a set of metrics for navigational modelsthat has been proposed for analyzing the quality of web applications in terms of size and structural complexity. these metrics were defined and validated using a formal framework (DISTANCE) for software measure construction that satisfies the measurement needs of empirical softwareengineering research. Some experimental studies have shown that complexity affects the ability to understand and maintain conceptual models. In order to prove this, we also made a controlled experiment to observe how the proposed metrics can be used as early maintainability indicators.
We present an approach to managing formal models using Model Driven Architecture (MDA) technologies that delivers analysis techniques through integration withthe design tools and repositories that practitioners use. ...
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ISBN:
(纸本)0769520359
We present an approach to managing formal models using Model Driven Architecture (MDA) technologies that delivers analysis techniques through integration withthe design tools and repositories that practitioners use. Expert modelling knowledge is captured in domain-specific languages and meta-model constraints. these are represented using UML and colocated with designs and analysis models, providing a flexible and visible approach to managing semantic associations. the approach relies on standards to permit deployment in multiple tools. We demonstrate our approach with an example in which queuing-network models are associated with UML design models to predict average case performance.
Many Siemens operating companies build software products or products with a high software content (e.g. embedded software). Siemens Corporate Research has had the unique opportunity over the last few years to look at ...
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ISBN:
(纸本)0769519806
Many Siemens operating companies build software products or products with a high software content (e.g. embedded software). Siemens Corporate Research has had the unique opportunity over the last few years to look at the analysis models from which the software products were derived, analyze them, and recommend changes. All the models investigated define commercial products that are or will be in the marketplace in the near future. Because of the size and complexity of the models (some running over a thousand use cases) the internal analysis tool design advisor was created to facilitate their inspection. An analysis was then performed on several models with interesting results.
this paper describes a novel methodology for predicting fault prone modules. the methodology is based on Dempster-Shafer (D-S) belief networks. Our approach consists of three steps: First, building the Dempster-Shafer...
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ISBN:
(纸本)0769520359
this paper describes a novel methodology for predicting fault prone modules. the methodology is based on Dempster-Shafer (D-S) belief networks. Our approach consists of three steps: First, building the Dempster-Shafer network by the induction algorithm;Second, selecting the predictors (attributes) by the logistic procedure;third, feeding the predictors describing the modules of the current project into the inducted Dempster-Shafer network and identifying fault prone modules. We applied this methodology to a NASA dataset. the prediction accuracy of our methodology is higher than that achieved by logistic regression or discriminant analysis on the same dataset.
Estimating the effort required for software process activities continues to present difficulties for software engineers, particularly given the uncertainty and subjectivity associated withthe many factors that can in...
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ISBN:
(纸本)0769519873
Estimating the effort required for software process activities continues to present difficulties for software engineers, particularly given the uncertainty and subjectivity associated withthe many factors that can influence effort. It is therefore advisable that managers review their estimates and plans on an ongoing basis during each project so that growing certainty can be harnessed in order to improve their management of future project tasks. In this paper we investigate the potential of using effort data recorded for completed project tasks to predict the effort needed for subsequent activities. Our approach is tested against data collected from sixteen projects undertaken by a single organization over a period of eighteen months. Our findings suggest that, at least in this case, the idea that there are,standard proportions' of effort for particular development activities does not apply. Estimating effort on this basis would not have improved the management of these projects. We did find, however, that in most cases simple linear regression enabled us to produce better estimates than those provided by the project managers. Moreover, combining the managers' estimates withthose produced by regression modeling also led to improvements in predictive accuracy. these results indicate that, in this organization, prior-phase effort data could be used to augment the estimation process already in place in order to improve the management of subsequent process tasks. this provides further confirmation of the value of local data and the benefits of quite simple quantitative analysis methods.
In this article an overview of the state of the art of QFD in software development or also called software QFD is given. the differences between classic QFD in manufacturing industries and software QFD are described F...
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ISBN:
(纸本)0769519806
In this article an overview of the state of the art of QFD in software development or also called software QFD is given. the differences between classic QFD in manufacturing industries and software QFD are described Following certain software specific QFD models (Zultner, Shindo, Ohmori, Herzwurm and Schockert), which can be considered as the most appreciated ones in theory as well as in practice, are introduced Experiences in practice withthese software QFD models are presented as well. Finally, through explaining the main principles of a special QFD variant for e-commerce, called Continuous QFD (CQFD), the article will show that QFD is suitable for planning electronic business applications as well.
this panel aims to open up a discussion how methods and models from Marketing can help RE community to face the changing landscape of software development. the panel Chair and panelists are coming from Information Sys...
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ISBN:
(纸本)0769519806
this panel aims to open up a discussion how methods and models from Marketing can help RE community to face the changing landscape of software development. the panel Chair and panelists are coming from Information Systems Science, softwareengineering and Marketing Science. the session is anticipated to address the issues associated with eliciting requirements from consumers, and how to involve them to the softwareengineering process. We approach the issue from RE perspective and try to connect New Product Development from Marketing to it, in order to find ways to integrate the knowledge between the disciplines.
In market-driven development of product software, a crucial decision for each candidate requirement is whether or not to select it for implementation in the next release. this paper presents an analytical model of the...
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ISBN:
(纸本)0769519806
In market-driven development of product software, a crucial decision for each candidate requirement is whether or not to select it for implementation in the next release. this paper presents an analytical model of the requirements selection process, which is used for reasoning about decision quality. A network of queues, with two classes of Jobs, modelsthe selection of requirements of different quality. the feasibility of model parameter estimation is validated in a survey involving product managers and system engineers. the results show that some of the respondents have made internally consistent parameter estimations, indicating that the model is relevant and its parameters understandable. It is also shown that a majority of the consistent respondents estimate that most of their implemented product requirements am incorrectly selected the main objective of the model is to provide tools for evaluation of improvement proposals by estimating the impact of process change.
Model checking is emerging as a popular technology for reasoning about behavioral properties of a wide variety of software artifacts including: requirements models, architectural descriptions, designs, implementations...
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