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排序方式: 共有790条查询结果,搜索用时 15 毫秒
1.
Alexandre Szklo Giovani Machado Roberto Schaeffer Jacqueline Mariano Janaí na Sala Marina Tavares 《Catalysis Today》2005,106(1-4):123-128
This paper assesses the impacts of a GTL plant on the expansion of Brazil's oil refining segment. The GTL plant (50,000 bpd) was sized to start up operations in 2015, producing diesel and naphtha through the indirect route (FT-synthesis). This plant will consume the non-associated natural gas production from the recent discoveries at the Santos Basin (around 419 Bm3), and the associated gas production from the Campos Basin. Both basins are located in the Southeast of Brazil, the most populated, rich and industrialized region of the country. Two different criteria for refinery expansion were simulated in order to meet oil product demand scenarios. Findings show that depending on the refinery expansion criteria considered GTL will play a fundamental hole to meet the oil product demand forecast to Brazil in the next 10 years. 相似文献
2.
With the increasing use of electric motors in automobiles—in some cases as many as 100 electric motors per vehicle—alternatives to ferrite magnetic materials are under consideration. If more powerful magnetic materials could be implemented, size reductions in these motors could result in curb weight reductions that lead to improved fuel economy. NdFeB magnets are attractive as potential replacement materials, due to their higher flux density and thus smaller required size; however, high material costs have limited their implementation. To investigate the economic competitiveness of alternative magnetic materials, technical cost models (TCMs) were developed and used to examine the manufacturing economics related to the production of both NdFeB and ferrite magnets. Results from the TCMs are used to identify the cost drivers and opportunities for cost reductions. Subsequent investigations will include effects on vehicle fuel efficiency, and the environmental impact of magnet manufacture and disposal. 相似文献
3.
A national effort, begun in 1972 to increase the numbers of minorities in engineering, has made substantial progress, but the attrition for minority students is still estimated at 70%. To address the problem, Project Preserve was designed to confirm, by demonstration, the results of previous research showing that the combination of explicit cognitive development, close relationships with faculty, and strong bonds to an institution can raise the performance and retention of minority engineering students. The project enrolled over 100 minority engineering students who had been dismissed from freshman engineering studies on other campuses or placed on academic probation, but whose high school grades and SAT scores were indicative of success. They were channeled into participating institutions chosen for their record of basic support services, willingness to augment or restructure those services, and for variation among institutional variables: Xavier University of Louisiana (XU), California State University at Northridge (CSUN), and City College of the City University of New York (CCNY). A 2 1/2 hour battery of evaluation instruments was given to 79 students upon entry and to 26 students upon their attaining Junior status after two years in the program. The results demonstrated that: (1) an admirable 64% of would-be drop outs had achieved Junior status or were still enrolled in engineering at the conclusion of two years; (2) cognitive growth occurred on basic memory skills and one critical thinking skill, but there were institutional differences in the extent of intellectual development, with Xavier producing the most change; (3) closer relationships to faculty were outcomes; (4) the most positive feelings about, or bonding to, the institution occurred at Xavier University, while the most evidence of social participation and connectedness occurred at CSUN. 相似文献
4.
Kvin Nay William J. Smiles Jacqueline Kaiser Luke M. McAloon Kim Loh Sandra Galic Jonathan S. Oakhill Andrew L. Gundlach John W. Scott 《International journal of molecular sciences》2021,22(8)
As life expectancy has increased, particularly in developed countries, due to medical advances and increased prosperity, age-related neurological diseases and mental health disorders have become more prevalent health issues, reducing the well-being and quality of life of sufferers and their families. In recent decades, due to reduced work-related levels of physical activity, and key research insights, prescribing adequate exercise has become an innovative strategy to prevent or delay the onset of these pathologies and has been demonstrated to have therapeutic benefits when used as a sole or combination treatment. Recent evidence suggests that the beneficial effects of exercise on the brain are related to several underlying mechanisms related to muscle–brain, liver–brain and gut–brain crosstalk. Therefore, this review aims to summarize the most relevant current knowledge of the impact of exercise on mood disorders and neurodegenerative diseases, and to highlight the established and potential underlying mechanisms involved in exercise–brain communication and their benefits for physiology and brain function. 相似文献
5.
Colin?WilbornEmail author Jacqueline?Beckham Bill?Campbell Travis?Harvey Melyn?Galbreath Paul?La Bounty Erika?Nassar Jennifer?Wismann Richard?Kreider 《Journal of the International Society of Sports Nutrition》2005,2(2):4-31
Obesity and its associated disorders are a growing epidemic across the world. Many genetic, physiological, and behavioral
factors play a role in the etiology of obesity. Diet and exercise are known to play a valuable role in the treatment and prevention
of obesity and associated disorders such as hypertension, heart disease, and diabetes. Therefore, the purpose of this review
is to examine the prevalence, etiology, consequences, and treatment of obesity. 相似文献
6.
Multilayer hybrid visualizations to support 3D GIS 总被引:3,自引:0,他引:3
In this paper, we present a unique hybrid visualization system for spatial data. Although some existing 3D GIS systems offer 2D views they are typically isolated from the 3D view in that they are presented in a separate window. Our system is a novel hybrid 2D/3D approach that seamlessly integrates 2D and 3D views of the same data. In our interface, multiple layers of information are continuously transformed between the 2D and 3D modes under the control of the user, directly over a base terrain. In this way, our prototype system is able to depict 2D and 3D views within the same window. This has advantages, since 2D and 3D visualizations can each be easier to interpret in different contexts.In this work we develop this concept of a hybrid visualization by presenting a comprehensive set of capabilities within our distinctive system. These include new facilities such as: hybrid landmark, 3D point, and chart layers, the grouping of multiple hybrid layers, layer painting, the merging of layer controls and consistent zooming functionality. 相似文献
7.
Identifying discriminating variables between teachers who fully integrate computers and teachers with limited integration 总被引:1,自引:0,他引:1
Julie Mueller Eileen Wood Teena Willoughby Craig Ross Jacqueline Specht 《Computers & Education》2008,51(4):1523-1537
Given the prevalence of computers in education today, it is critical to understand teachers’ perspectives regarding computer integration in their classrooms. The current study surveyed a random sample of a heterogeneous group of 185 elementary and 204 secondary teachers in order to provide a comprehensive summary of teacher characteristics and variables that best discriminate between teachers who integrate computers and those who do not. Discriminant Function Analysis indicated seven variables for elementary teachers and six for secondary teachers (accounting for 74% and 68% of the variance, respectively) that discriminated between high and low integrators. Variables included positive teaching experiences with computers; teacher’s comfort with computers; beliefs supporting the use of computers as an instructional tool; training; motivation; support; and teaching efficacy. Implications for support of computer integration in the classroom are discussed. 相似文献
8.
Jacqueline G. Ord 《AI & Society》1995,9(1):80-90
Value in the British National Health Service have shifted away from patient care towards financial control. However, in the quest for efficiency, huge amounts of NHS money have been wasted on computer system which failed. In this paper, I draw on a case study to explore some of the ethical issues which underlie this kind of waste of resources. Issues include the gap between public pronouncements and personal experience, the chaos of which lies behind the facade of rationality, and the systematic silencing of people, usually women, who question the viability of computer systems which are created for private gain rather than public service. 相似文献
9.
Bennett JC Krishnamoorthy V Liu S Grout RW Hawkes ER Chen JH Shepherd J Pascucci V Bremer PT 《IEEE transactions on visualization and computer graphics》2011,17(12):1822-1831
We present a new framework for feature-based statistical analysis of large-scale scientific data and demonstrate its effectiveness by analyzing features from Direct Numerical Simulations (DNS) of turbulent combustion. Turbulent flows are ubiquitous and account for transport and mixing processes in combustion, astrophysics, fusion, and climate modeling among other disciplines. They are also characterized by coherent structure or organized motion, i.e. nonlocal entities whose geometrical features can directly impact molecular mixing and reactive processes. While traditional multi-point statistics provide correlative information, they lack nonlocal structural information, and hence, fail to provide mechanistic causality information between organized fluid motion and mixing and reactive processes. Hence, it is of great interest to capture and track flow features and their statistics together with their correlation with relevant scalar quantities, e.g. temperature or species concentrations. In our approach we encode the set of all possible flow features by pre-computing merge trees augmented with attributes, such as statistical moments of various scalar fields, e.g. temperature, as well as length-scales computed via spectral analysis. The computation is performed in an efficient streaming manner in a pre-processing step and results in a collection of meta-data that is orders of magnitude smaller than the original simulation data. This meta-data is sufficient to support a fully flexible and interactive analysis of the features, allowing for arbitrary thresholds, providing per-feature statistics, and creating various global diagnostics such as Cumulative Density Functions (CDFs), histograms, or time-series. We combine the analysis with a rendering of the features in a linked-view browser that enables scientists to interactively explore, visualize, and analyze the equivalent of one terabyte of simulation data. We highlight the utility of this new framework for combustion science; however, it is applicable to many other science domains. 相似文献
10.
The authors surveyed 347 public sector employees on 4 measurement occasions to investigate the conceptual distinctiveness of the psychological contract and perceived organizational support (POS) and how they are associated over time. Results support the distinctiveness of the 2 concepts. In terms of their interrelationships over time, by drawing on psychological contract theory the authors found little support for a reciprocal relationship between POS and psychological contract fulfillment. Under an alternative set of hypotheses, by drawing on organizational support theory and by separating psychological contract fulfillment into its 2 components (perceived employer obligations and inducements), the authors found that perceived employer inducements were positively related to POS, which, in turn, was negatively related to perceived employer obligations. The results suggest that POS and the components of psychological contract fulfillment are more important in predicting organizational citizenship behavior than psychological contract fulfillment. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献