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Terrorist and criminal acts are now considered credible risks in the process industries. Deliberate attacks on the nation's petroleum refineries and chemical plants would pose a significant threat to public welfare, national security, and the US economy. To-date, the primary response of government and industry has been on improved security to prevent attacks and the associated consequences. While prevention is clearly preferred, the potential for successful attacks must be addressed. If plant security is breached, the extent of the inflicted damage is determined by the available plant safety systems and procedures. We refer to this "inside the gate" response as process threat management. The authors have initiated a joint industry/academia study to address: the level of safety provided by existing plant equipment and safety systems in response to a terrorist act, and identification of process (rather than security) needs or opportunities to address this new safety concern. This paper describes the initial perspectives and issues identified by the team at the beginning of the study.  相似文献   
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This study focuses on the uncertainties in the fate of nitrogen (N) in the Netherlands. Nitrogen inputs into the Netherlands in products, by rivers, and by atmospheric deposition, and microbial and industrial fixation of atmospheric N2 amount to about 4450 Gg N y–1. About 60% of this N is transported out of the Netherlands in products. The fate of the remaining 40%, however, is less clear. We discuss uncertainties in losses to the atmosphere (as ammonia or through denitrification), by leaching and runoff, and in N accumulation in biomass and soils. These processes may account for the fate of about 40% of the N in the Netherlands, and for the fate of about 60% of the N in Dutch agricultural soils. Reducing uncertainties in the estimates of these fluxes is necessary for reducing the impact of excess N in the environment. In particular, monitoring the environmental effects of ammonia emissions and nitrate leaching to groundwater and aquatic systems requires an increased understanding of the fate of N. Uncertainties arise because (1) some N fluxes cannot be measured directly and are usually quantified indirectly as the balance in N budgets, (2) direct measurements of N fluxes have inevitable inaccuracies, (3) lack of experimental data and other information (e.g. statistics) needed for upscaling, (4) large spatial and temporal variability of fluxes, and (5) poor understanding of the processes involved. These uncertainties can be reduced by additional experimental studies and by further development of process-based models and N budget studies. We prioritize these future research needs according to a range of different criteria.  相似文献   
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There is a growing interest among teachers in using games as a part of their lesson plans. A standardised, interoperable approach to the sharing of such game-based lesson plans would allow teachers and educational technologists to compare and contrast Digital Game Based Learning scenarios, allowing best practices and lessons learned to emerge. Although games can be used as ‘add-ons’ in educational contexts, greater benefits can be attained by integrating games more fully into the educational process, i.e. by repurposing existing games to target the specific learning objectives. In this article we analyse this problem. We developed two possible solutions based on the integration and the interaction of games and learning scenarios. The first solution is based on ‘pedagogical wrappers’, where games are linked to e-learning flows but without interaction and communication. The second solution sees a tighter integration which supports ongoing interaction and communication between game and e-learning flow. We applied both solutions to a generic game. This game was firstly programmed in Action Script and later re-used for learning purposes and represented in IMS Learning Design. We analysed the pros and cons of each solution and identify research topics for further research.  相似文献   
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A new method is proposed for forecasting age-specific mortality and fertility rates observed over time. This approach allows for smooth functions of age, is robust for outlying years due to wars and epidemics, and provides a modelling framework that is easily adapted to allow for constraints and other information. Ideas from functional data analysis, nonparametric smoothing and robust statistics are combined to form a methodology that is widely applicable to any functional time series data observed discretely and possibly with error. The model is a generalization of the Lee-Carter (LC) model commonly used in mortality and fertility forecasting. The methodology is applied to French mortality data and Australian fertility data, and the forecasts obtained are shown to be superior to those from the LC method and several of its variants.  相似文献   
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The present study used perspectives from the general literature on college alcohol consumption to examine mediational influences of peer, environmental, and parental variables on heavy drinking for student athlete and nonathlete samples. Eight hundred thirty-five freshmen who differed in organized sports involvement were compared on heavy drinking outcomes, peer norms, environmental influences, and parental communication. College athletes reported significantly more heavy drinking experiences than nonathletes. Peer norms, environmental influences, and parental communication were all significant mediators of the athlete-heavy drinking relationship. Athletes reported a higher perception of peer drinking, peer approval of drinking, higher alcohol availability, and direct drink offers, which, in turn, were related to higher rates of heavy drinking. Parental communication mediated the athlete-heavy drinking relationship differently, depending on the specific topic of conversation. Discussion surrounding the importance of incorporating a variety of interventions aimed at reducing collegiate athlete drinking on the basis of the peer, environmental, and parental influences observed in the present analyses are presented. Limitations and directions for future research are also noted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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现在,电子制造行业必须满足无铅标准,并且已经取得了很大的进展,整个行业正在了解可靠的无铅方案。业内正在生产高性能无铅电路板,并且已经制订出无铅处理的新标准。本文重点介绍无铅焊接处理中的回流焊工艺考虑因素。[第一段]  相似文献   
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