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Different Case Studies (different + case_studies)
Selected AbstractsOptimal production cost of the power producers with linear ramp model using FDR PSO algorithmEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 2 2010M. Anitha Abstract In practice, the power producers have to be rescheduled for power generation beyond their power limits to meet vulnerable situations like credible contingency and increase in load conditions. During this process, the ramping cost is incurred if they violate their permissible elastic limits. In this paper, optimal production costs of the power producers are computed with ramping cost considering stepwise and piecewise linear ramp rate limits using fitness distance ratio particle swarm optimization (FDR PSO) algorithm. Transient stability constraints are also considered while formulating the optimal power flow (OPF) problem as additional rotor angle inequality constraints. The proposed algorithm is demonstrated on a practical 39 bus New England and 62 bus Indian Utility system with different case studies. Copyright © 2008 John Wiley & Sons, Ltd. [source] Fluid-induced seismicity: Pressure diffusion and hydraulic fracturingGEOPHYSICAL PROSPECTING, Issue 2 2009S.A. Shapiro ABSTRACT Borehole fluid injections are common for the development of hydrocarbon and geothermic reservoirs. Often they induce numerous microearthquakes. Spatio-temporal dynamics of such induced microseismic clouds can be used to characterize reservoirs. However, a fluid-induced seismicity can be caused by a wide range of processes. Here we show that linear pore pressure relaxation and a hydraulic fracturing are two asymptotic end members of a set of non-linear diffusional phenomena responsible for seismicity triggering. To account for the whole range of processes we propose a rather general non-linear diffusional equation describing the pore pressure evolution. This equation takes into account a possibly strong enhancement of the medium permeability. Both linear pore pressure relaxation and hydraulic fracturing can be obtained as special limiting cases of this equation. From this equation we derive the triggering front of fluid induced seismicity, which is valid in the general case of non-linear pore pressure diffusion. We demonstrate corresponding seismicity signatures on different case studies. [source] The rise of the ,network organisation' and the decline of discretionHUMAN RESOURCE MANAGEMENT JOURNAL, Issue 2 2003Irena Grugulis This article explores the implications of ,networked' and ,flexible' organisations for the work and skills of professionals/ Drawing on material from four different case studies, it reviews work that is outsourced (involving IT professionals and housing benefit caseworkers), work that is done by teachers contracted to a temporary employment agency and work organised through an inter-firm network (chemical production workers). In each case work that was outsourced was managed very differently to that undertaken in-house, with managerial monitoring replacing and reducing employees' discretion. New staff in these networks had fewer skills when hired and were given access to a narrower range of skills than their predecessors. By contrast, the production staff directly employed on permanent contracts in the inter-firm network were given (and took) significant amounts of responsibility, with positive results for both their skills and the work processed. Yet, despite the negative impact they have on skills, outsourcing and subcontracting are a far more common means of securing flexibility than organisational collaboration. [source] Forecasting migration of cereal aphids (Hemiptera: Aphididae) in autumn and springJOURNAL OF APPLIED ENTOMOLOGY, Issue 5 2009A. M. Klueken Abstract The migration of cereal aphids and the time of their arrival on winter cereal crops in autumn and spring are of particular importance for plant disease (e.g. barley yellow dwarf virus infection) and related yield losses. In order to identify days with migration potentials in autumn and spring, suction trap data from 29 and 45 case studies (locations and years), respectively, were set-off against meteorological parameters, focusing on the early immigration periods in autumn (22 September to 1 November) and spring (1 May to 9 June). The number of cereal aphids caught in a suction trap increased with increasing temperature, global radiation and duration of sunshine and decreased with increasing precipitation, relative humidity and wind speed. According to linear regression analyses, the temperature, global radiation and wind speed were most frequently and significantly associated with migration, suggesting that they have a major impact on flight activity. For subsequent model development, suction trap catches from different case studies were pooled and binarily classified as days with or without migration as defined by a certain number of migrating cereal aphids. Linear discriminant analyses of several predictor variables (assessed during light hours of a given day) were then performed based on the binary response variables. Three models were used to predict days with suction trap catches ,1, ,4 or ,10 migrating cereal aphids in autumn. Due to the predominance of Rhopalosiphum padi individuals (99.3% of total cereal aphid catch), no distinction between species (R. padi and Sitobion avenae) was made in autumn. As the suction trap catches were lower and species dominance changed in spring, three further models were developed for analysis of all cereal aphid species, R. padi only, and Metopolophium dirhodum and S. avenae combined in spring. The empirical, cross-classification and receiver operating characteristic analyses performed for model validation showed different levels of prediction accuracy. Additional datasets selected at random before model construction and parameterization showed that predictions by the six migration models were 33,81% correct. The models are useful for determining when to start field evaluations. Furthermore, they provide information on the size of the migrating aphid population and, thus, on the importance of immigration for early aphid population development in cereal crops in a given season. [source] On the effectiveness of clone detection by string matchingJOURNAL OF SOFTWARE MAINTENANCE AND EVOLUTION: RESEARCH AND PRACTICE, Issue 1 2006Stéphane Ducasse Abstract Although duplicated code is known to pose severe problems for software maintenance, it is difficult to identify in large systems. Many different techniques have been developed to detect software clones, some of which are very sophisticated, but are also expensive to implement and adapt. Lightweight techniques based on simple string matching are easy to implement, but how effective are they? We present a simple string-based approach which we have successfully applied to a number of different languages such COBOL, JAVA, C++, PASCAL, PYTHON, SMALLTALK, C and PDP-11 ASSEMBLER. In each case the maximum time to adapt the approach to a new language was less than 45 minutes. In this paper we investigate a number of simple variants of string-based clone detection that normalize differences due to common editing operations, and assess the quality of clone detection for very different case studies. Our results confirm that this inexpensive clone detection technique generally achieves high recall and acceptable precision. Over-zealous normalization of the code before comparison, however, can result in an unacceptable numbers of false positives. Copyright © 2005 John Wiley & Sons, Ltd. [source] Taxonomic sufficiency in two case studies: where does it work better?MARINE ECOLOGY, Issue 2009Tiziano Bacci Abstract In marine macrobenthos studies the identification of organisms at species level is the best entry to ecological and biological information about the animals. An accurate identification requires excellent conservation of the organisms, reliable fauna description, experts and lengthy work in the laboratory. The aim of this work is to test taxonomic sufficiency (TS) in two deliberately selected different case studies to understand whether and how the taxonomic complexity of a benthic assemblage influences the results of TS and where it works better. The first benthic settlement was collected in an area characterized by homogeneous depth and grain size composition (case study A) around an off-shore gas platform, while the second one was collected along a coast-wide transect in an area with human pressure limited to fishing activities (case study B). Univariate and multivariate statistical analysis was used to assess differences in the taxonomic structure of benthic assemblages and to test TS on the two different datasets. TS seems to work in both sites, from species to higher taxonomic levels, and the family taxonomic level appears the best compromise for taxonomic resolution when an accurate identification is not achievable. The application of TS does not indicate a significant difference between the two datasets and appears therefore to be a valid instrument to analyse and describe the structure of benthic settlements in the case of taxonomically complex communities. [source] Provisions Made for Prosperity and Affluence: Karl Sigmund Franz Freiherr von Stein zum Altenstein and the Establishment of the Gärtnerlehranstalt in PrussiaCENTAURUS, Issue 1 2007Björn Brüsch Taking three different case studies, the paper sets out to demonstrate the importance of the garden in land improvement, and how this interest resulted in the foundation of an institution for the specific training and instruction of gardeners. Not only was this Königliche Gärtnerlehranstalt (Royal Gardener's Institute), along with the Royal Botanical Garden and the Society for the Advancement of Horticulture in the Royal Prussian states, seen as an outstanding centre for the improvement of the Prussian landscape, it also combined practical theoretical, and scientific instruction. Merging agrarian and horticultural utility with beautiful gardens, it was aimed at the scientific schooling of land cultivators and experts of plant culture so providing technical support for those industries dedicated to garden culture. Copying the magnificent example of the Parisian Jardin des plantes not only was the garden regarded as a place in which the state's affluence and prosperity was rooted, it also combined cameralistic as well as the scientific and political ideas of the time. The gardener became part of the agrarian political economy. [source] | ||||||||||