5,146 research outputs found

    Optimization of fuzzy analogy in software cost estimation using linguistic variables

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    One of the most important objectives of software engineering community has been the increase of useful models that beneficially explain the development of life cycle and precisely calculate the effort of software cost estimation. In analogy concept, there is deficiency in handling the datasets containing categorical variables though there are innumerable methods to estimate the cost. Due to the nature of software engineering domain, generally project attributes are often measured in terms of linguistic values such as very low, low, high and very high. The imprecise nature of such value represents the uncertainty and vagueness in their elucidation. However, there is no efficient method that can directly deal with the categorical variables and tolerate such imprecision and uncertainty without taking the classical intervals and numeric value approaches. In this paper, a new approach for optimization based on fuzzy logic, linguistic quantifiers and analogy based reasoning is proposed to improve the performance of the effort in software project when they are described in either numerical or categorical data. The performance of this proposed method exemplifies a pragmatic validation based on the historical NASA dataset. The results were analyzed using the prediction criterion and indicates that the proposed method can produce more explainable results than other machine learning methods.Comment: 14 pages, 8 figures; Journal of Systems and Software, 2011. arXiv admin note: text overlap with arXiv:1112.3877 by other author

    The task of digital information management

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    This paper tries to contrast digital decay with paper decay, explains how digitisation further accelerates accessing information through the trio factors accessibility, ease of use and perceived utility. Also discusses related issues including proliferation of gray content on the Web

    Pattern of card catalogue consultation in a special library

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    A three day sample observation of card catalogue consultation by users at ISRO Satellite Centre (ISAC) Library has been made and results recorded. Users have been subsequently questioned about the purposes for which catalogue was consulted. The paper describes the card catalogue system of the library, the method followed and limitations of the study. The data in appropriate tables has revealed that classified catalogue is not used; Report Number Catalogue is least used and subject catalogue is consulted to the maximum. It is also found that more than half of the consultations of card catalogue are to locate documents, one-fourth is to interact with circulation system, one-tenth is to make a comprehensive search for references on a topic and rest for miscellaneous purposes. It is concluded, based on the results, that arrangement of charged out tray at circulation counter be changed to classified order and classified catalogue itself may have to be dispensed with

    Resource sharing and networking of engineering college libraries

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    This lecture on resource sharing and networking of engineering college libraries in Karnataka delivered at the second annual seminar of ASSIST (Asian Society for Social Service, Information Science and Technology) explains the need for resource sharing, enumerates the buzz words relating to "cooperation" and "e-revolution", points out the inherent limitations as well as certain facts and hurdles in the process of resource sharing. It examines cost considerations of resources versus their use considerations as well as strength of resources versus strength of user need considerations. The lecture enumerates various possibilities and areas for resource sharing. In conclusion, some suggestions and tips are offered to overcome the hurdles for effective resource sharing. Two case studies, namely subscription to e-journals and user-orientation at ISAC (ISRO Satellite Centre) library are also presented

    The shear dynamo problem for small magnetic Reynolds numbers

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    We study large-scale dynamo action due to turbulence in the presence of a linear shear flow, in the low conductivity limit. Our treatment is nonperturbative in the shear strength and makes systematic use of both the shearing coordinate transformation and the Galilean invariance of the linear shear flow. The velocity fluctuations are assumed to have low magnetic Reynolds number (Rm) but could have arbitrary fluid Reynolds number. The magnetic fluctuations are determined to lowest order in Rm by explicit calculation of the resistive Green's function for the linear shear flow. The mean electromotive force is calculated and an integro-differential equation is derived for the time evolution of the mean magnetic field. In this equation, velocity fluctuations contribute to two different kinds of terms, the C and D terms, in which first and second spatial derivatives of the mean magnetic field, respectively, appear inside the spacetime integrals. The contribution of the D terms is such that the time evolution of the cross-shear components of the mean field do not depend on any other components excepting themselves. Therefore, to lowest order in Rm but to all orders in the shear strength, the D terms cannot give rise to a shear-current assisted dynamo effect. Casting the integro-differential equation in Fourier space, we show that the normal modes of the theory are a set of shearing waves, labelled by their sheared wavevectors. The integral kernels are expressed in terms of the velocity spectrum tensor, which is the fundamental quantity that needs to be specified to complete the integro-differential equation description of the time evolution of the mean magnetic field.Comment: Near-final version; Accepted for publication in the Journal of Fluid Mechanics; References added; 22 pages, 2 figure

    WEST-3 wind turbine simulator development. Volume 1: Summary

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    This report is a summary description of WEST-3, a new real-time wind turbine simulator developed by Paragon Pacific Inc. WEST-3 is an all digital, fully programmable, high performance parallel processing computer. Contained in the report are descriptions of the WEST-3 hardware and software. WEST-3 consists of a network of Computational Units (CUs) working in parallel. Each CU is a custom designed high speed digital processor operating independently of other CUs. The CU, which is the main building block of the system, is described in some detail. A major contributor to the high performance of the system is the use a unique method for transferring data among the CUs. The software aspects of WEST-3 covered in the report include the preparation of the simulation model (reformulation, scaling and normalization), and the use of the system software (Translator, Linker, Assembler and Loader). Also given is a description of the wind turbine simulation model used in WEST-3, and some sample results from a study conducted to validate the system. Finally, efforts currently underway to enhance the user friendliness of the system are outlined; these include the 32-bit floating point capability, and major improvements in system software

    WEST-3 wind turbine simulator development. Volume 2: Verification

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    The details of a study to validate WEST-3, a new time wind turbine simulator developed by Paragib Pacific Inc., are presented in this report. For the validation, the MOD-0 wind turbine was simulated on WEST-3. The simulation results were compared with those obtained from previous MOD-0 simulations, and with test data measured during MOD-0 operations. The study was successful in achieving the major objective of proving that WEST-3 yields results which can be used to support a wind turbine development process. The blade bending moments, peak and cyclic, from the WEST-3 simulation correlated reasonably well with the available MOD-0 data. The simulation was also able to predict the resonance phenomena observed during MOD-0 operations. Also presented in the report is a description and solution of a serious numerical instability problem encountered during the study. The problem was caused by the coupling of the rotor and the power train models. The results of the study indicate that some parts of the existing WEST-3 simulation model may have to be refined for future work; specifically, the aerodynamics and procedure used to couple the rotor model with the tower and the power train models

    Nonperturbative quasilinear approach to the shear dynamo problem

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    We study large-scale dynamo action due to turbulence in the presence of a linear shear flow. Our treatment is quasilinear and equivalent to the standard `first order smoothing approximation'. However it is non perturbative in the shear strength. We first derive an integro-differential equation for the evolution of the mean magnetic field, by systematic use of the shearing coordinate transformation and the Galilean invariance of the linear shear flow. We show that, for non helical turbulence, the time evolution of the cross-shear components of the mean field do not depend on any other components excepting themselves; this is valid for any Galilean-invariant velocity field, independent of its dynamics. Hence, to all orders in the shear parameter, there is no shear-current type effect for non helical turbulence in a linear shear flow, in quasilinear theory in the limit of zero resistivity. We then develop a systematic approximation of the integro-differential equation for the case when the mean magnetic field varies slowly compared to the turbulence correlation time. For non-helical turbulence, the resulting partial differential equations can again be solved by making a shearing coordinate transformation in Fourier space. The resulting solutions are in the form of shearing waves, labeled by the wavenumber in the sheared coordinates. These shearing waves can grow at early and intermediate times but are expected to decay in the long time limit.Comment: 31 pages: typos corrected & references adde
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