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971.
Politicians and policy-makers, as well as modellers, often nurses an expectation that model derived results is an objective source of information that can be used to support decisions. However, several prerequisites have to be dealt with in order to ensure that models can be used as legitimate and efficient tools in water resource management. Based on empirical material from recent studies on the use of models in stakeholder dialogues, mainly focusing on catchment nutrient transport, two central problems are identified: (a) Models are laden with choices and thus depend on assumptions and priorities of modellers. (b) There are several factors that influence ability and willingness of stakeholders (as information recovers) to criticize or accept results of the modelling exercise. Recognized factors likely to influence stakeholders' acceptance of model derived results include issues at stake, stakeholders' ability to criticize model derived information, and their trust in the institutions that have developed or applied the used models. Identified prerequisites for successful use of models in integrated water resource management include: consideration of user relevance, awareness of and preparedness to handle constraints linked to communication of model-based results, transparency of used models and data and of involved uncertainties, mutual respect between experts and stakeholders and between involved stakeholder groups, a robust institutional network, and sufficient time for dialogues. Development and use of strategies for participatory modelling, based on a continuous dialogue between experts and stakeholders is recommended as a way to facilitate that the prerequisites for a successful use of models in water resource management are fulfilled.  相似文献   
972.
塔河油田深井穿盐膏层钻井液技术   总被引:4,自引:0,他引:4  
深井盐膏层钻井施工风险极大,常会引起卡钻和套管损坏,影响安全钻井。通过对塔河油田深井盐膏层矿物组分、理化特征等进行综合分析,阐明井壁失稳的主要原因,为选择钻井液体系提供理论基础;对适应于该段的钻井液体系和现场维护处理技术进行了探索,提出了欠饱和盐水钻井液技术方案,并在T913井、TK827井、TK1106井进行了现场应用。结果表明,井下复杂大幅度降低,钻井周期大幅度缩短,经济效益较好。  相似文献   
973.
In this study, we highlighted differences in the standards used in performance tests of solar collectors. We analyzed testing results for different types of solar collectors to determine the effects of the collector area and mass flow rate, which were not necessarily consistent across all tests. Our analysis showed that the factor,F′ (τα), including collector efficiency factor (F′), could be correlated with the flow rate or area regardless of the collector type. Moreover, the collector loss coefficient (F′U L ) per flow rate or area for an evacuated collector was less that of a flat-plate collector; this was also correlated with the flow rate or area, regardless of the type of evacuated collector. As a result of this analysis, we propose a modified heat loss coefficient that includes the effects of all parameters that can be considered in a performance test and show that this coefficient could better describe the thermal characteristics of various types of solar collectors.  相似文献   
974.
Polydorou and Capsalis [1] pioneered the concept of POCA distribution to study the statistical behavior of the fast fading characteristics in an indoor environment under the assumption of finite number of scatters. In this note, we derive a comprehensive class of formulas for the POCA distribution to help better statistical modeling of the fast fading characteristics. The calculations involve use of several special functions and their properties.  相似文献   
975.
采用金相显微镜,X射线衍射仪,透明电子显微镜,扫描电子显微镜等仪器分析对比35CrMo钢和35CrMoCe钢离子硫氮碳复合渗特性,探讨了稀土铈和加速离子硫氮碳复合渗的原因,研究结果表明,两种钢的复合渗层均由硫化物层,氮碳化物层的扩展层构成;稀土铈显著地提高了渗层深度,铈具有细化组织的作用,提供了更多可供氮碳原子扩散的通道。  相似文献   
976.
利用模糊评判方法确定张东构造油藏储量计算的可靠程度   总被引:1,自引:0,他引:1  
张巨河油田张东构造地处大港滩海交接处,海域部分探井少.目前用油藏描述方法计算的探明储量,其落实程度备受关注.储量落实程度的评价是一个多因素综合评判问题,而且这些因素还分属不同层次.模糊综合评判是应用较为广泛的模糊数学方法之一.该方法建立的综合评判涉及三个要素,即因素集、评判集和单因素评判,由此所构造的模糊评判关系是模糊综合评判的基础.本文用该方法对张东构造沙二段油藏的探明储量落实程度作了尝试性评价.  相似文献   
977.
Circular groove guide is a kind of waveguide for millimeter waves with low loss, large dimensions, and low dispersion. In this paper, the dominant mode characteristics of it is analysed. The technique that mode macthing method combines with point matching method is used to derive the Nth-order characteristic equation of the guide. The 1st order, 2nd order and 3rd order approximate curves that the normalized cutoff wavelength of circular groove guide varies with c/a are given. The attenuation curves are given at 1mm, 1.5mm and 3mm wavelength. The numerical results are in well agreement with the experimental results published.  相似文献   
978.
坐标测量机激光非接触式测头的研制   总被引:2,自引:0,他引:2  
本文介绍适用子精密大型测试仪器──坐标测量机的激光非接触式测头的研制。该测头采用PSD作为敏感元件并采用单片机技术完成对测量数据的处理。  相似文献   
979.
Sulfur in coal causes problems in coal processing and utilization, therefore the chemical beneficiation of coal has gained widespread attention. Using three coal samples with high sulfur content the effect of desulfurization has been studied. For Nantong coal containing 4.25% total sulfur under the condition sulfur reduction increased from 38.8% upto 62.4% the released sulfur was generally sulfate and pyrite, but the organic sulfur almost remained constant. When alkali treatment was performed at 370°C, organic sulfur removal of Donglin and Yanzhou coal was to 50.6% and 57.3% respectively.  相似文献   
980.
The casp9 protein plays a critical role in apoptosis induced by a variety of death stimuli. A regulator of apoptosis, Apaf-1, binds to and activates pro-casp9 in the presence of cytochrome c and dATP, a requirement that is bypassed by deletion of the WD-40 repeats located in the C-terminal half of Apaf-1. In this report, we used constitutively active Apaf-1 mutant lacking the WD-40 repeat region to study the mechanism and regulation of pro-casp9 activation. Mutational analysis revealed that only a small portion of the CED-4 homologous region (residues 456-559) could be deleted without destroying the ability of Apaf-1-(1-559) to activate pro-casp9. Apaf-1 can self-associate to form oligomers. Disruption of Apaf-1 self-association by deletion (Delta109-559) or mutation of the P-loop region (K149R) abrogated Apaf-1-mediated pro-casp9 activation. Forced oligomerization of the caspase recruitment domain of Apaf-1 was sufficient for pro-casp9 activation. Dimerization of chimeric Fpk-pro-casp9 protein with the dimerizer drug FK1012 induced pro-casp9 processing and apoptosis in cells. Significantly, the C-terminal region containing WD-40 repeats interacted with its N-terminal CED-4 homologous region, as determined by immunoprecipitation experiments. Importantly, expression of the WD-40 repeat region inhibited Apaf-1 self-association and proteolytic activation of pro-casp9. These studies provide a mechanism by which Apaf-1 promotes autoactivation of pro-casp9 through Apaf-1 self-association, a process that is negatively regulated by the WD-40 repeats.  相似文献   
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