A UML-based quantitative framework for early prediction of resource usage and load in distributed real-time systems

This paper presents a quantitative framework for early prediction of resource usage and load in distributed real-time systems (DRTS). The prediction is based on an analysis of UML 2.0 sequence diagrams, augmented with timing information, to extract timed-control flow information. It is aimed at improving the early predictability of a DRTS by offering a systematic approach to predict, at the design phase, system behavior in each time instant during its execution. Since behavioral models such as sequence diagrams are available in early design phases of the software life cycle, the framework enables resource analysis at a stage when design decisions are still easy to change. Though we provide a general framework, we use network traffic as an example resource type to illustrate how the approach is applied. We also indicate how usage and load analysis of other types of resources (e.g., CPU and memory) can be performed in a similar fashion. A case study illustrates the feasibility of the approach.

An Experimental Comparison of the Maintainability of Object-Oriented and Structured Design Documents

Several important questions still need to be answered regarding the maintainability of object-oriented design documents. This paper focuses on the following issues: are object-oriented design documents easier to understand and modify than structured design documents? Do they need to comply with quality guidelines such as the ones provided by Coad and Yourdon? What is the impact of such quality standards on the understandability and modifiability of design documents? Answers can be based on informed opinion or empirical evidence. Since software technology investments are substantial and contradictory opinions exist regarding design strategies, performing empirical studies on these topics is a relevant research activity. This paper presents a controlled experiment performed with computer science students as subjects. Results strongly suggest that quality guidelines based on Coad and Yourdon principles have a beneficial effect on the maintainability of object-oriented design documents. However, there is no strong evidence regarding the alleged higher maintainability of object-oriented design documents over structured design documents. Furthermore, results suggest that object-oriented design documents are more sensitive to poor design practices, in part because their cognitive complexity becomes increasingly unmanageable. However, because our ability to generalise these results is limited, they should be considered as preliminary, i.e., it is very likely that they can only be generalised to programmers with little object-oriented training and programming experience. Such programmers can, however, be commonly found on maintenance projects. As well as additional research, external replications of this study are required to confirm the results and achieve confidence in these findings.     

Conceptual masking in brief visual displays.

Examined a paradigm used to study conceptual masking. This paradigm uses a variant of the partial report procedure, wherein a display of characters is preceded or followed by a probe character and Ss must report whether the probe was in the display or not. Ss were 7 undergraduates. Results show that neither specific orienting effects of the probe nor eye movements to the probe character could explain the pattern of data found in earlier studies (V. Di Lollo and M. Moscovitch; see record 1984-14011-001). Data are discussed in the context of P. Dixon's (see record 1986-21077-001) model of performance within this paradigm. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

海洋植物与蓝色化妆品

讲述了海藻和人体皮肤之间的相似处以及它为什么能让蓝色化妆品起到有效的皮肤护理作用，并着重讲述了碧欧特海洋精华Biotech Marine公司的10个功效很全面的重点产品。     

Has feature integration theory come unglued? A reply to Tsal.

Y. Tsal (see record 1989-31807-001) presented a critical review of feature integration theory (FIT) and of a number of studies that have purported to show a direct relationship between focal attention and the perception of illusory conjunctions. Conceptual difficulties with the theory are highlighted, and Tsal concluded that the reviewed studies have not provided sufficient empirical support. We argue that neither Tsal's conceptual criticism nor his empirical ones are convincing enough to warrant rejection of FIT and that he has not suggested an obvious and unique theoretical alternative that inspires an appropriate empirical test. A problem for FIT that Tsal did not raise is discussed. That is, the visual primitives assumed by the theory are not clearly specified or related to known neurophysiological or psychophysical evidence concerning early vision. Nevertheless, we conclude that FIT remains a viable theoretical framework. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigating the use of analysis contracts to improve the testability of object‐oriented code

A number of activities involved in testing software are known to be difficult and time consuming. Among them is the definition and coding of test oracles and the isolation of faults once failures have been detected. Through a thorough and rigorous empirical study, we investigate how the instrumentation of contracts could address both issues. Contracts are known to be a useful technique in specifying the precondition and postcondition of operations and class invariants, thus making the definition of object‐oriented analysis or design elements more precise. It is one of the reasons the Object Constraint Language (OCL) was made part of the Unified Modeling Language. Our aim in this paper is to reuse and instrument contracts to ease testing. A thorough case study is run where we define OCL contracts, instrument them using a commercial tool and assess the benefits and limitations of doing so to support the automated detection of failures and the isolation of faults. As contracts can be defined at various levels of detail, we also investigate the cost and benefit of using contracts at different levels of precision. We then draw practical conclusions regarding the applicability of the approach and its limitations. Copyright © 2003 John Wiley & Sons, Ltd.