66,670 research outputs found

    Complexity and maintenance : a comparative study of object-oriented and structured methodologies : a thesis presented in partial fulfilment of the requirements for the degree of Master of Business Studies in Information Systems at Massey University

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    Maintenance has been found to be one of the most expensive phases in the life of an information system. It has been suggested that the use of object-oriented methods instead of traditional structured methods may be one way of reducing the cost of maintenance required for an information system. This thesis is an attempt to determine whether the object-oriented approach does in fact undergo a relatively smaller increase in complexity when subjected to a change in specifications than a similar system that is developed using a "structured methodology", and is therefore easier to maintain. The methodologies used in this study were Yourdon's (1989) Modern Structured Methodology and Booch's (1994) Object-Oriented methodology. The analysis phase of both methodologies were applied to the same case study twice in order to evaluate the effects of a change in the system's specifications. Once the two models for each methodology were complete, various metrics were applied to the structured system and a separate set of metrics were applied to the object-oriented system. The results of the models and the metrics were then analysed and validated in order to determine which system suffered a smaller proportional increase in complexity as a result of the changes to the system. It was found that overall, the object-oriented system proved to undergo a smaller increase in complexity, and it was therefore easier to maintain as a result of the changes than the structured system

    Automated Pin-Dot Marking Effects on A709-Gr50 Steel Plate Fatigue Capacity

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    During fabrication of multi-piece steel bridge assemblies, markings are often made on the steel surface to identify/track individual pieces or to provide reference for fabrication layout or later erection. Automated marking methods such as computer numerically controlled (CNC) pin-dot marking offer fabrication efficiencies; however, for marked steel sections subjected to frequent or repeated loading (i.e. bridge girders) many code specifications require experimental testing to verify any marking effects on fatigue capacity. In this study, the effects of automated pin-dot markings on the fatigue capacity of A709-Gr50 bridge steel are experimentally investigated from 13 specimens considering 2 marking frequencies (corresponding to marking speeds of 50in./min and 10in./min), 2 applied stress ranges (35ksi and 45ksi), and 2 material orientations (both longitudinal and transverse plate rolling directions). Results from the 13 high-cycle fatigue tests, along with other fatigue test results from the literature indicate that the surface markings from the automated marking systems have no effect on the fatigue capacity of the A709-Gr50 plate. All marked specimens achieved higher fatigue capacities than would be expected for unmarked specimens meeting the AASHTO fatigue detail category ‘A’ designation

    The Eigenvalue Problem for Linear and Affine Iterated Function Systems

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    The eigenvalue problem for a linear function L centers on solving the eigen-equation Lx = rx. This paper generalizes the eigenvalue problem from a single linear function to an iterated function system F consisting of possibly an infinite number of linear or affine functions. The eigen-equation becomes F(X) = rX, where r>0 is real, X is a compact set, and F(X)is the union of f(X), for f in F. The main result is that an irreducible, linear iterated function system F has a unique eigenvalue r equal to the joint spectral radius of the functions in F and a corresponding eigenset S that is centrally symmetric, star-shaped, and full dimensional. Results of Barabanov and of Dranishnikov-Konyagin-Protasov on the joint spectral radius follow as corollaries.Comment: 18 pages, 3 figure

    Field Experiment Tests for Discrimination against Hispanics in the U.S. Rental Housing Market

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    This article tests for discrimination against Hispanics in the U.S. rental housing market using e-mail correspondence with landlords advertising units online. We divide Hispanics into two groups: those that appear assimilated into American culture and recent immigrants. We find little difference in the treatment of assimilated Hispanics and whites; however, Hispanics we portray as recent immigrants receive less favorable treatment with margins of net discrimination as large as 6.89% of landlords. We also find discrimination varies significantly at the region level and by the ethnic composition of neighborhoods
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