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61.
Ove Wolfgang Arne Haugstad Birger Mo Anders Gjelsvik Ivar Wangensteen Gerard Doorman 《Energy》2009,34(10):1642
The Norwegian Energy Act that came into force in 1991 deregulated the electricity market and removed the former obligation power companies had to supply electricity to the geographical area they were responsible for. Hence producers can supply electricity on the basis of profitability. In 2007 the Energy Act was evaluated by the Government. As a part of this, a study concerning hydro reservoir handling before and after deregulation was carried out by SINTEF. Public statistics show that average hydro reservoir levels measured in per cent of reservoir capacity have been reduced after 1990. We have used the power-market model EMPS1 (EFI's Multi-area Power-market Simulator) to analyze if this reduction can be explained by natural variation in climatic variables or by structural changes that have occurred after 1990. Simulation results show that the reduced reservoir levels cannot be explained by natural variation in climatic variables. Structural changes such as increased transmission capacities can, however, explain some of the reduction. Our study does not indicate that the present reservoir handling gives reservoir levels that are too low. In this paper we also describe the stochastic dynamic optimization problem for long-term hydropower scheduling, and we explain how this problem actually is solved by the EMPS model. 相似文献
62.
Touchard Gerard Benyamina M. Borzeix J.A.G. Romat H. 《Industry Applications, IEEE Transactions on》1989,25(6):1067-1072
The mechanism of static electrification of hydrocarbon liquids flowing through artificially roughed metallic pipes is analyzed. Only the case of a laminar flow is considered. The equations of motion of the liquid are computed in the case of circular pipes with periodic roughness of rectangular cross section in the axial direction. The results reveal the formation of eddies, which depend on the size and the period of the roughness and on the Reynolds number. After determining the charge convected in a smooth pipe and the velocity profile in a rough one, it is possible to predict the convected space charge in terms of the roughness characteristics. The experimental results obtained with different rough pipes and several Reynolds numbers are in good agreement with the predictions, making it possible to explain the observations made during previous experiments on static electrification in rough pipes 相似文献
63.
Gerard J. Puccio Roger L. Firestien Christina Coyle Cristina Masucci 《Creativity & Innovation Management》2006,15(1):19-33
A major focus within the field of creativity has been on the development of methodologies aimed at deliberately nurturing creative thinking. These methodologies have attempted to mirror the creative process in ways that allow individuals and groups to explicitly call on and employ their creative faculties. In an attempt to uplift employees’ creative capabilities many of these methodologies have been introduced into organizations through training programs, as well as through application to business challenges. Do these methods work? What is the empirical evidence that these deliberate creative process methods enhance employees’ creativity? Though there are a handful of creative process methods, few have married the concern for application with an interest in demonstrating the benefits of these applied efforts through systematic research. Creative Problem Solving (CPS), one of the more popular creative process models, has been one of the rare exceptions. The purpose of this paper is to synthesize the research literature that reports on the impact of CPS training carried out within organizational contexts, that is training programs that involved professionals or students working on real business challenges. Additionally, the positive benefits of CPS are further examined through reports that cite the outcomes of applying CPS to business challenges. In a field replete with methods that have been commercialized, it is imperative to strike a balance between research and practice as an imbalance towards practice may foster a field dominated by individuals who offer untested products and services. 相似文献
64.
We studied the late-stage spinodal decomposition of the polystyrene–cyclohexanol system in relation to membrane formation. Phase separation was effected by the removal of thermal energy from the homogeneous polymer solution. The ultimate morphology of the phase-separated systems has been studied using electron microscopy and has been found to be strongly affected by the quenching time. A shift from a highly interconnected open-cell structure to a closed-cell structure has been observed, indicating the transition of the spinodal decomposition from early to late stages. The cell growth in the late stage has been quantitatively analyzed and a power-law relationship between the cell size and quenching time has been found. The resulting exponent of 0.61 is consistent with literature values from light-scattering measurements, as well as from theoretical derivations. © 1995 John Wiley & Sons, Inc. 相似文献
65.
GB Karlsson M Halloran D Schenten J Lee P Racz K Tenner-Racz J Manola R Gelman B Etemad-Moghadam E Desjardins R Wyatt NP Gerard L Marcon D Margolin J Fanton MK Axthelm NL Letvin J Sodroski 《Canadian Metallurgical Quarterly》1998,188(6):1159-1171
CD4+ T lymphocyte depletion in human immunodeficiency virus type 1 (HIV-1)-infected humans underlies the development of acquired immune deficiency syndrome. Using a model in which rhesus macaques were infected with chimeric simian-human immunodeficiency viruses (SHIVs), we show that both the level of viremia and the structure of the HIV-1 envelope glycoprotein ectodomains individually contributed to the efficiency with which CD4(+) T lymphocytes were depleted. The envelope glycoproteins of recombinant SHIVs that efficiently caused loss of CD4(+) T lymphocytes exhibited increased chemokine receptor binding and membrane-fusing capacity compared with those of less pathogenic viruses. These studies identify the HIV-1 envelope glycoprotein ectodomains as determinants of CD4(+) T lymphocyte loss in vivo and provide a foundation for studying pathogenic mechanisms. 相似文献
66.
J. Gerard Wolff 《New Generation Computing》1995,13(2):187-214
This article is an overview of a programme of research based on the conjecture thatall kinds of computing and formal reasoning may usefully be understood as information compression by pattern matching, unification and metrics-guided search. The research aims to develop this idea into a theory of computing to integrate and simplify diverse concepts in the field. The research also aims to develop a ‘new generation’ computing system, based on the theory, to integrate and simplify diverse kinds of computing and to achieve more flexibility and ‘intelligence’ than conventional computers. Software simulations of the proposed new system provide a concrete expression of the developing theory and a test-bed for the ideas. The background to the research is briefly reviewed including evidence that information compression is a significant element in biological information processing systems. Concepts ofinformation andredundancy are described as a basis for describing how information compression may be achieved by the comparison ormatching of patterns, the merging orunification of patterns which are the same, together withmetrics-guided search (e.g., ‘hill climbing’, ‘beam search’) to maximise compression for a given computational effort. The main elements of the SP theory and of the proposed SP system are described with a summary of developments to date. Some of the kinds of computing which be interpreted as information compression are briefly reviewed. These include: the ‘low level’ workings of conventional computers; information retrieval, pattern recognition and de-referencing of identifiers; unsupervised inductive learning (grammatical inference, data mining, automatic organisation of software and of knowledge bases); the execution of mathematical or computing functions; deductive and probabilistic inference; parsing and natural language processing; planning and problem solving. Areas of uncertainty where further work is needed are indicated at appropriate points throughout the article. 相似文献
67.
C García Rodríguez DR Cundell EI Tuomanen LF Kolakowski C Gerard NP Gerard 《Canadian Metallurgical Quarterly》1995,270(42):25178-25184
Streptococcus pneumoniae has been shown to utilize the platelet activating factor receptor for binding and invasion of host cells (Cundell, D. R., Gerard, N. P., Gerard, C., Idanpaan-Heikkila, I., and Tuomanen, E. I. (1995) Nature, in press). Because bacterial binding is in part carbohydrate dependent, and the human platelet-activating factor (PAF) receptor bears a single N-linked glycosylation sequence in the second extracellular loop, we undertook studies to determine the role of this epitope in PAF receptor function. Binding of pneumococci to COS cells transfected with the human PAF receptor is greatly reduced for a receptor mutant that bears no N-linked glycosylation site. Immunohistochemical and binding analyses show decreased expression of the non-glycosylated molecule on the cell membrane relative to the wild type receptor; however, metabolic labeling and immunopurification indicate it is synthesized intracellularly at a level similar to the native molecule. A mutant receptor encoding a functional glycosylation site at the NH2 terminus is better expressed at the cell surface compared with the non-glycosylated form, indicating that trafficking to the cell surface is facilitated by glycosylation, but its location is relatively unimportant. The binding affinity for PAF is not significantly effected by the presence or location of the carbohydrate, and variations in cell surface expression have little influence on signal transduction, as the non-glycosylated PAF receptor is equally effective for activation of phospholipase C as the native molecule. These data are supportive of pneumococcal binding on protein moiety(ies) of the PAF receptor and indicate that N-glycosylation facilitates expression of the protein on the cell membrane. 相似文献
68.
Examined employers' hiring preferences and practices related to American Psychological Association (APA) approved and non-APA-approved training program graduates, based on 414 job advertisements listed in the APA Monitor and a survey of 104 employers who had advertised positions. Results indicate that employers would prefer to hire graduates of APA-approved training programs. 82% of employers in the academic area and 77% of those in the applied area reported that they would give hiring preference to APA-approved program graduates. (2 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
69.
Alain Gerard 《International Journal of Engineering Science》1982,20(4):565-574
In an infinite space, we study the propagation of elastic spherical waves emitted by a source point placed outside a given finite set of concentric elastic spherical layers. The exact solution (displacements fields) of this problem is determined by a new method which avoids solving the totality of equations and boundary conditions. From these results we deduce those corresponding to some particular cases. 相似文献
70.
Gerard M. Ludtka David E. Laughlin 《Metallurgical and Materials Transactions A》1981,12(12):2083-2091
The microstructures of three high strength, high purity Al-Zn-Mg-Cu alloys, in the T6 temper, were characterized extensively
using quantitative optical metallography and quantitative transmission electron microscopy. Only the solute content (Mg +
Zn) of these alloys was varied for this study. These alloys were shown to be identical in grain size and shape, dispersoid
(E-phase) and grain boundary precipitate (ν) populations, and precipitate free zone widths. The matrix microstructures consisted
of ordered GP zones and ν′ and differed only in the volume fraction of these strengthening precipitates. The higher solute
alloys had the higher yield strengths and volume fractions of matrix precipitates. Subsequent slip behavior analysis of prestrained
tensile specimens demonstrated that slip band spacings and slip step heights increased with increasing solute content for
the same macroscopic strain (εp = 0.02). A work softening model by Hornbogen and Gahr was shown to predict this tendency toward increased strain localization
with higher solute levels.
Formerly a Research Assistant at Carnegie-Mellon University 相似文献