Performance prediction for centrifugal pumps is now mainly based on numerical calculation and most of the studies merely focus on one model. Therefore, the research results are not representative. To make an improveme...Performance prediction for centrifugal pumps is now mainly based on numerical calculation and most of the studies merely focus on one model. Therefore, the research results are not representative. To make an improvement of numerical calculation method and performance prediction for centrifugal pumps, performance of six centrifugal pump models at design flow rate and off design flow rates, whose specific speed are different, were simulated by using commercial code FLUENT. The standard k-t turbulence model and SIMPLEC algorithm were chosen in FLUENT. The simulation was steady and moving reference frame was used to consider the impeller-volute interaction. Also, how to dispose the gap between impeller and volute was presented and the effect of grid number was considered. The characteristic prediction model for centrifugal pumps is established according to the simulation results. The head and efficiency of the six models at different flow rates are predicted and the prediction results are compared with the experiment results in detail. The comparison indicates that the precision of head and efficiency prediction are all less than 5%. The flow analysis indicates that flow change has an important effect on the location and area of low pressure region behind the blade inlet and the direction of velocity at impeller inlet. The study shows that using FLUENT simulation results to predict performance of centrifugal pumps is feasible and accurate. The method can be applied in engineering practice.展开更多
Research infrastructure is crucial for development of research,and thus the evaluation of its performance is important.However,existing researches mostly focus on its past observations,lacking of a prediction for futu...Research infrastructure is crucial for development of research,and thus the evaluation of its performance is important.However,existing researches mostly focus on its past observations,lacking of a prediction for future. In this paper, procedures are proposed to predict the distribution for the number of papers published in a certain future year. The publication reliability,which is defined as the probability that the number of published papers in the future year is bigger than a pre-specified number,is evaluated. Illustrative examples are proposed to show the applications of the model.展开更多
目的:分析国内外高血压相关风险预测研究的现状,为开展更丰富、全面的科学研究及更好地进行疾病管理提供参考。方法:计算机检索近10年中国知网、Web of Science核心合集数据库中的高血压预测模型相关文献,借助CiteSpace 6.1.R6绘制图谱...目的:分析国内外高血压相关风险预测研究的现状,为开展更丰富、全面的科学研究及更好地进行疾病管理提供参考。方法:计算机检索近10年中国知网、Web of Science核心合集数据库中的高血压预测模型相关文献,借助CiteSpace 6.1.R6绘制图谱,包括发文趋势、关键词共现和聚类、突现词分析、时间线图。结果:共纳入578篇文献。国内外年发文量均呈增长趋势。研究热点集中在对老年、农村人口等不同特征高血压人群的诊断模型及预后模型。研究前沿集中在列线图、机器学习等高血压预测模型构建途径。结论:近10年国内外的研究热点在预测因子上存在差异。今后国内研究者可结合中医元素构建更多的高血压相关预测模型,进一步进行模型的联合、对比及优化。展开更多
本文借助文献计量法分析预测微生物学研究概况、研究热点与发展趋势,为今后的研究提供思路。在Web of Science核心合集数据库中,检索2006—2021年间以预测微生物学为主题的相关文献,基于文献计量法及CiteSpace软件进行可视化分析展示。...本文借助文献计量法分析预测微生物学研究概况、研究热点与发展趋势,为今后的研究提供思路。在Web of Science核心合集数据库中,检索2006—2021年间以预测微生物学为主题的相关文献,基于文献计量法及CiteSpace软件进行可视化分析展示。预测微生物学文献数量显著增长,从2006年的57篇增至2021年的138篇;研究方向主要是食品科学技术、微生物学、传染病学、生物技术应用微生物学等领域;全球共有73个国家/地区开展预测微生物学的研究,发文量排名前15的国家共占总发文量的42.90%;中国发文量在全球排名第6,且与美国、欧洲等国家/地区跨区域合作密切;诊断、性能、死亡率、治疗、参数估计、乳酸菌、猪肉、指南、风险因素等关键词是被广泛关注的热点。预测微生物学以其快速、高效、准确等优点未来将在食品科学、生物学、医学等研究领域发挥重要作用。展开更多
基金supported by National Outstanding Young Scientists Founds of China (Grant No. 50825902)National Natural Science Foundation of China (Grant No. 50509009)
文摘Performance prediction for centrifugal pumps is now mainly based on numerical calculation and most of the studies merely focus on one model. Therefore, the research results are not representative. To make an improvement of numerical calculation method and performance prediction for centrifugal pumps, performance of six centrifugal pump models at design flow rate and off design flow rates, whose specific speed are different, were simulated by using commercial code FLUENT. The standard k-t turbulence model and SIMPLEC algorithm were chosen in FLUENT. The simulation was steady and moving reference frame was used to consider the impeller-volute interaction. Also, how to dispose the gap between impeller and volute was presented and the effect of grid number was considered. The characteristic prediction model for centrifugal pumps is established according to the simulation results. The head and efficiency of the six models at different flow rates are predicted and the prediction results are compared with the experiment results in detail. The comparison indicates that the precision of head and efficiency prediction are all less than 5%. The flow analysis indicates that flow change has an important effect on the location and area of low pressure region behind the blade inlet and the direction of velocity at impeller inlet. The study shows that using FLUENT simulation results to predict performance of centrifugal pumps is feasible and accurate. The method can be applied in engineering practice.
基金Ministry of Education Project,China(No.2014GL15)
文摘Research infrastructure is crucial for development of research,and thus the evaluation of its performance is important.However,existing researches mostly focus on its past observations,lacking of a prediction for future. In this paper, procedures are proposed to predict the distribution for the number of papers published in a certain future year. The publication reliability,which is defined as the probability that the number of published papers in the future year is bigger than a pre-specified number,is evaluated. Illustrative examples are proposed to show the applications of the model.
文摘目的:分析国内外高血压相关风险预测研究的现状,为开展更丰富、全面的科学研究及更好地进行疾病管理提供参考。方法:计算机检索近10年中国知网、Web of Science核心合集数据库中的高血压预测模型相关文献,借助CiteSpace 6.1.R6绘制图谱,包括发文趋势、关键词共现和聚类、突现词分析、时间线图。结果:共纳入578篇文献。国内外年发文量均呈增长趋势。研究热点集中在对老年、农村人口等不同特征高血压人群的诊断模型及预后模型。研究前沿集中在列线图、机器学习等高血压预测模型构建途径。结论:近10年国内外的研究热点在预测因子上存在差异。今后国内研究者可结合中医元素构建更多的高血压相关预测模型,进一步进行模型的联合、对比及优化。
文摘本文借助文献计量法分析预测微生物学研究概况、研究热点与发展趋势,为今后的研究提供思路。在Web of Science核心合集数据库中,检索2006—2021年间以预测微生物学为主题的相关文献,基于文献计量法及CiteSpace软件进行可视化分析展示。预测微生物学文献数量显著增长,从2006年的57篇增至2021年的138篇;研究方向主要是食品科学技术、微生物学、传染病学、生物技术应用微生物学等领域;全球共有73个国家/地区开展预测微生物学的研究,发文量排名前15的国家共占总发文量的42.90%;中国发文量在全球排名第6,且与美国、欧洲等国家/地区跨区域合作密切;诊断、性能、死亡率、治疗、参数估计、乳酸菌、猪肉、指南、风险因素等关键词是被广泛关注的热点。预测微生物学以其快速、高效、准确等优点未来将在食品科学、生物学、医学等研究领域发挥重要作用。
