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61.
通过对动态规划法、线性规划法、非线性规划法及遗传算法等泵站优化运行算法的综述,对泵站运行优化方法的发展提出新的看法。  相似文献   
62.
Performance analysis of transcritical organic rankine cycle   总被引:1,自引:0,他引:1  
The performance analysis of a transcritical organic Rankine cycle system driven by exhaust heat is presented by using 24 organic working fluids. Four parameters, such as the net power output, thermal efficiency, exergy efficiency, and mass flow rate of working fluid, are used to evaluate the performance of this recovery cycle. The results reveal that the maximum net power can be obtained for the saturated ORC, when T1/TC is about 0.98~0.99,and the working fluid with higher critical temperature has more net power output. For the supercritical ORC, the higher expander inlet temperature will benefit the net power output, thermal efficiency, and exergy efficiency, as long as the expander inlet pressure isnnot too low. However, the influences of expander inlet pressure on these performance parameters are linked with the expander inlet temperature and working fluids. The capability of doing power output of supercritical ORC is not always better than that of subcritical ORC. Parameters, such as net power, thermal efficiency, and exergy efficiency, and mass flow rate are discontinuous in the process from subcritical conditions to supercritical conditions.  相似文献   
63.
Reasons for performing study: Disturbances in skeletal development, primarily osteochondrosis (OC) and palmar/plantar osseous fragments (POF), have been commonly reported as problems in young horses. However, there are few reports of such findings for epidemiological analyses or breeding purposes. Objectives: To evaluate equine hospital data as a possible source of information for genetic evaluations by estimating prevalence and heritability of OC in the stifle, hock and fetlock joints and of POF in the fetlock. Methods: Data on Swedish Warmblood (SWB) horses were obtained from a large equine hospital in south Sweden. Prevalences were based on radiographic examinations of 879 screened horses, mainly evaluated as part of a prepurchase examination and 3639 horses with a reported history of orthopaedic problems. For the heritability study the 2 data sources were pooled and 3199 examined horses with pedigree information were considered for the linear animal model analyses. Results: The overall prevalence of OC was 13% (stifle 9%, hock 6% and dorsal osseous fragments in fetlock [DOF] 10%) and POF 10%. The overall heritability of OC was 0.05 on the visible binomial scale. The corresponding heritabilities for OC in the stifle were 0.03, hock 0.08, DOF 0.10 and POF 0.13. These values correspond to heritabilities of 0.09–0.38 on the underlying quantitative scale. Conclusions and potential relevance: Obtained prevalences and heritabilities were in accordance with other studies, supporting the hypothesis that data regularly obtained from equine hospitals may be a valuable source in studies of inherited disorders such as OC and POF. There is a need for more standardised documentation of diagnoses and consistent recording of identity of examined horses using passports or breed databases. Compilation of results from major clinics is desired in order to cover most progenies of stallions used in a region or nation.  相似文献   
64.
围绕权力和翻译的关系探究翻译中的意识形态问题,并试图证实这一论点:唐朝的佛经汉译表明翻译活动,特别是宗教文本的翻译,在翻译政策、译者和翻译策略方面受制于意识形态。通过揭示翻译文本生成中的操纵机制和政治动因,人们能够更深刻地理解翻译,特别是宗教文本翻译的本质。翻译不是纯粹的语言交际活动,而是权力控制下源语和译语的对话。  相似文献   
65.
All active stages of the tick Ixodes ricinus were collected monthly at two sites in northern Spain between the years 2000 and 2007. We used percentile accumulation of the active stage in the environment to evaluate simple and coherent correlations between accumulation of the active stages of larvae and nymphs and medium‐resolution MODIS satellite‐derived information on the climate, including monthly and accumulated temperature and the Normalized Difference Vegetation Index (NDVI). This framework is not intended to predict the actual abundance of ticks in the field as a measure of the hazard to humans, but to provide a basic structure for addressing the phenology of the tick in its geographic range. We demonstrated that the accumulation of larval ticks in the active stage is a sigmoid function of the accumulated temperature from the beginning of the calendar year. We also demonstrated that the accumulated temperature necessary to recruit nymphs from the questing larval stage is a function of the changes in accumulated larvae and nymphs and the accumulated temperature and NDVI recorded by the Aqua sensor. The low p‐values obtained in the regressions confirmed that such recruitment can be calculated using time intervals to estimate, for example, the beginning of the questing period or the time of the year when a population peak can be expected. The comparison among predicted and actual accumulated temperatures between larvae and nymph recruitment had an averaged error of ±20 days in one complete year. The use of accumulated temperature and NDVI proposed in this study opens up the re‐evaluation of reports on the phenology of the tick in Europe. This framework is intended to evaluate the same correlations along the tick's range and predict its phenological patterns in areas of pathogen transmission risk for humans.  相似文献   
66.
通过正交实验法优化了红菇子实体多糖热水浸提法的条件为水料比30,浸提温度60℃,浸提时间3h.在此提取条件下,提取率为4.33%.粗多糖经过DEAE-纤维素阴离子交换柱层析得到D1、D2、D3和D4四个组分.研究了红菇粗多糖及其各组分的还原能力、对·OH的清除作用以及清除NO2-的作用,以此来评价该多糖的抗氧化活性.结果表明,红菇多糖具有一定的还原力,对·OH具有明显的清除作用,在体外模拟胃液条件下对NO2-有一定的清除作用.  相似文献   
67.
本文系统、全面地讨论了数字化地籍图数据处理的各种方法、特性及其应用范围。并结合实例对利用已知面积校正数字化坐标的平差计算方法作了详细的讨论。通过一系列的数据处理 ,可以向地理信息系统提供精度可靠的地理基础数据。  相似文献   
68.
文章提出了利用森林资源连续清查固定样地进行植被种类和生物量调查的技术方法。此方法通过选择适当时间,提高调查者相关知识,确定样地数量等措施,可满足植物区系调查的要求,对于植被类型确定,植物蕴藏量统计,经济植物开发利用保护的决策,植被演替规律的观测具有实用价值。  相似文献   
69.
遵照分类检索“以类索文,触类全貌,类目编排,严谨科学”的基本原则及本数据库独具专题综合性的特殊要求,以中国图管分类法为基础,优选有关1~4级类目、类号,显明简要的类目注释.并制定一套划分文献的规则,依类揭示本库所收录的节水农业文献信息,满足有关用户以类索文的需要。  相似文献   
70.
Abstract –  Many studies have reported that prey fish increase in body size with an increase in piscivore abundance, and this change may be explained mainly by two processes: release from intraspecific competition because of a reduction in the prey fish population and size-dependent selection by the piscivore. However, the evolutionary mechanism is not yet fully understood. Here, we first show the body-size dynamics of the semelparous gobiid fish Gymnogobius isaza , which is one of the prey fishes of the introduced largemouth bass, Micropterus salmoides . The data show the possibility that the goby body size might have changed in parallel to the number of largemouth bass from 1975 to 2002, which may be one of the best examples of the positive relationship between body size and predation rate. Furthermore, we explored a mathematical model to consider a body-size change of semelparous fish from an evolutionary viewpoint. The model provided the following qualitative predictions: (1) the optimal assimilation rate increases with predation pressure; (2) a rapid large-scale increase in predation pressure may exterminate the prey fish because of delayed evolution of the assimilation rate; and (3) the optimal assimilation rate increases when the prey fish is more likely to die through predation than through natural mortality or when it is difficult to grow larger because of low resource availability or insufficient foraging efficiency. Moreover, we propose a theoretical framework to evaluate the relative effects of ecological and evolutionary processes over the long term.  相似文献   
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