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991.
John Sheffield Thomas M. Antonsen Jr. Lee A. Berry Michael R. Brown Jill P. Dahlburg Ronald C. Davidson Martin Greenwald Chris C. Hegna William McCurdy David E. Newman Claudio Pellegrini Cynthia K. Phillips Douglass E. Post Marshall N. Rosenbluth Thomas C. Simonen James Van Dam 《Journal of Fusion Energy》2000,19(3-4):229-244
This Panel was set up by the Fusion Energy Sciences Advisory Committee (FESAC) at its November 2000 meeting for the purpose of addressing questions from the Department of Energy concerning the theory and computing/simulation program of the Office of Fusion Energy Sciences. Although the Panel primarily addressed programmatic questions, it acknowledges that the theory and computing in fusion energy sciences has a stellar record of research successes. (A recent FESAC report entitled Opportunities in the Fusion Energy Sciences Program listed a number of theory and computing research highlights.) Last year the National Research Council performed an assessment of the quality of the fusion energy sciences program—including theory and computing—and concluded that the quality of its research is on a par with that of other leading areas of contemporary physical science. 相似文献
992.
993.
Ana Celia Mota Elisabeth Dumont James L. Smith 《Journal of Low Temperature Physics》1999,117(5-6):1477-1481
We have found a sharp transition at T
c2
= 350 mK in the vortex creep rate of a single crystal of (U
1–x
Th
x
)Be
13
with T
c
= 523 mK (x = 0.0275). For T T
c2
, no creep of vortices is observed in a time scale of 105
s, while for T
c2
< T < T
c
, vortices creep at very high rates (30% of decay from a metastable configuration in the first 105
s at T = 400 mK). The sharp transition occurs at the same temperature at which the second jump in the specific heat appears in these samples. Similar low levels of creep rates have been reported by us in the low–T superconducting phase of UPt
3.1 相似文献
994.
995.
A Genetic Programming Approach to Rainfall-Runoff Modelling 总被引:2,自引:1,他引:1
Planning for sustainable development of water resources relies crucially on the data available. Continuous hydrologic simulation based on conceptual models has proved to be the appropriate tool for studying rainfall-runoff processes and for providing necessary data. In recent years, artificial neural networks have emerged as a novel identification technique for the modelling of hydrological processes. However, they represent their knowledge in terms of a weight matrix that is not accessible to human understanding at present. This paper introduces genetic programming, which is an evolutionary computing method that provides a transparent and structured system identification, to rainfall-runoff modelling. The genetic-programming approach is applied to flow prediction for the Kirkton catchment in Scotland (U.K.). The results obtained are compared to those attained using two optimally calibrated conceptual models and an artificial neural network. Correlations identified using data-driven approaches (genetic programming and neural network) are surprising in their consistency considering the relative size of the models and the number of variables included. These results also compare favourably with the conceptual models. 相似文献
996.
Active centers, catalytic behavior, symbiosis and redox properties of MoV(Nb,Ta)TeO ammoxidation catalysts 总被引:1,自引:0,他引:1
Robert K. Grasselli Douglas J. Buttrey James D. Burrington Arne Andersson Johan Holmberg Wataru Ueda Jun Kubo Claus G. Lugmair Anthony F. Volpe Jr 《Topics in Catalysis》2006,38(1-3):7-16
Selective as well as waste forming active centers were defined for MoVNbTeO and MoVTaTeO catalysts in the ammoxidation of
propane to acrylonitrile and all catalytic functionalities were assigned to specific elements at the respective active centers.
Symbiosis between M1 and M2 phases of these catalysts was observed, with phase cooperation being more extensive in the Nb than Ta containing compositions.
The difference in catalytic effectiveness arises most likely because contact and surface area exposure of the two respective,
cooperating phase pairs are not equal. The M1 phase of the catalysts is reducible by propane and ammonia in the absence of dioxygen and is regenerable to its original,
fully oxidized state by dioxygen (air). No structural collapse is observed even after 120 C3H8 + NH3 reduction pulses. The so induced reduction of the catalyst extends up to 70 layers deep. The product distribution over the
first few pulses is very similar to that under catalytic conditions, supporting the concept that lattice oxygen is involved
in the catalytic ammoxidation process. Therefore, the ammoxidation of paraffins is a redox process, as is of course the well-known
olefin ammoxidation process. 相似文献
997.
James S. Wilkinson 《Journal of the American Ceramic Society》2002,85(6):1387-1390
Materials and processes for integrated optics are faced with increasing demands from telecommunications and instrumentation applications. Progress in three aspects of novel materials and processes are described: titanium-diffused sapphire waveguides and lasers, interferometric excimer laser ablation of waveguide gratings, and surface studies by waveguide surface plasmon resonance. 相似文献
998.
James B. Pocock Steven T. Kuennen John Gambatese Jon Rauschkolb 《Canadian Metallurgical Quarterly》2006,132(4):373-383
This report reviews guidance on constructability programs from a variety of sources and presents the current practice of constructability. The advice of several organizations and researchers is summarized to describe expectations for ideal constructability. Actual current constructability practice, based on results and analysis of a Constructability State of Practice survey, is described. Approximately 100 owners, architects, engineers, consultants, contractors, and construction managers answered the survey’s ten questions and provided written comments. The results provide a picture of current constructability practices in the architecture, engineering, and construction (AEC) industry and progress in recent years. Major conclusions include: (1) constructability has gained acceptance throughout the industry; (2) constructability efforts are clearly beginning in early project phases; (3) a wide variety of constructability techniques and new technologies are being implemented; and (4) obstacles to improving constructability remain, but may be changing. Finally, recommendations are provided based on areas where constructability practice can still be improved. This report is relevant to both industry practitioners and researchers. 相似文献
999.
This column presents information of interest to Division 26 members. Included are a candidate's statement from Division member Ludy T. Benjamin, Jr., who is running for President of the American Psychological Association. Also included are a report on the February 1998 Meeting of the APA Council of Representatives; information about the Wallace Russell Fund, nominations for division offices, fellows nominations, and division membership; meeting announcements; and information about access restrictions to the Stanley Milgram papers. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
1000.
Hoffman James E.; Houck Michael R.; MacMillan Frank W. III; Simons Robert F.; Oatman Lynn C. 《Canadian Metallurgical Quarterly》1985,11(1):50
Investigated the role of limited capacity processes in the detection of automatic targets in a dual-task paradigm using both behavioral and event-related potential (ERP) measures. Six right-handed undergraduates served as Ss. An automatic detection task was paired with another concurrent discrimination while the relative importance of each task was systematically varied. The resulting performance operating characteristic showed that both the speed and accuracy of automatic detection responses were affected by the allocation of attention. Reductions in the accuracy of each task were accompanied by reductions in the amplitude of a late-positive component of the ERP (P300). The latency of the P300 component elicited by automatic targets was increased in dual-task conditions. A comparison of behavioral and ERP measures suggested the involvement of 2 separate limited-capacity processes in automatic detection: one concerned with the formation of an episodic representation of target occurrence and the other with the execution of rapid motor responses. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献