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关键词： Coldwater fish   Waste pond   Waste heat recovery   Technical-economic factors  

摘要： The supply of heat for fish farms, especially during off-season production, is necessary for the establishment of commercial aquaculture. For this purpose, research was carried out on the supply of heating ener to a rainbow trout farm (cold water fish) using a waste heat recovery system in the city of Meshgin in Ardabil province. The study area has 20 indoor pools and 14 unguarded pools. The 14 pools that are in the indoor area, are used for this study. Seven pools of these 14 pools were at high altitude and other 7 pools were at low altitude. After collection of the temperature data for waste water ponds that had provided optimum temperature conditions in the off-season using geothermal fluid, three modes for waste heat recovery were designed according to the thermal, flow and physicochemical properties of the waste pond. In the first mode, the output of the first seven pools and the second seven pools were combined and the fluid flow rate reached to 24.92 L/sec. In the second mode, the output of the second seven pools (8.15 L/sec) was used to recover heat, and in the third case, the output of the first seven pools (at high-altitude pools and with the flow rate of 16.77 L/sec) was used to recover heat. After obtaining technical approval and determining the economic value of each component of the waste heat recovery circuit from specialized companies in Iran, the proposed systems were analyzed theoretically with COMSOL software. Because there was no equal rate of flow, velocity or geometry for comparison between the optimum state in the theoretical conditions of practice, the temperature differences between the input hot water and output cold water were used for all three modes of heat recovery. Technically, the results indicate that the second mode is best in both the theoretical and practical modes of the waste heat recovery circuit. The first mode recovery system had the smallest temperature difference between the hot water inlet and cold water outlet. Economical

关键词： EQUAL-AREA CRITERION   NUMERICAL-SIMULATION  

摘要： With the diversification of power systems and the application of power electronic technology, the uncertainty of power systems is becoming more and more serious, and the traditional deterministic transient stability analysis methods encounter severe challenges. In this paper, a practical method is proposed for transient stability analysis of stochastic multi-machine systems based on EEAC. Firstly, the stochastic differential equation model of multi-machine systems is established. Secondly, the stochastic multi-machine system is equivalent to a stochastic single-machine infinite bus system according to coherency. Finally, the acceleration and deceleration area is constructed, and Heun's method is used to seek the critical clearing time of the system. The method is applied to analyse transient stability of four machine system. Compared with the numerical simulation based on Monte Carlo method, the simplicity and effectiveness of the method are verified. The impact of stochastic disturbance intensity on stability is also presented.

关键词： 中学数学教师   数学课程改革   培训活动   立德树人   中青年   教育研究   会员单位   港澳台  

摘要： 一、概况本次活动共有来自全国除西藏、港澳台以外的所有省、直辖市、自治区的近2000名代表参加,覆盖范围广,受到全国中学数学教师、教育研究部门、各会员单位的高度重视.

关键词： Practical identifiability   Cardiovascular system   Mathematical model   Parameter identification   STRESSED BLOOD-VOLUME   VENTRICULAR INTERACTION   PRESSURE   HEART   IDENTIFICATION   FLOW  

摘要： Background and objective: Parameters of mathematical models of the cardiovascular system can be used to monitor cardiovascular state, such as total stressed blood volume status, vessel elastance and resistance. To do so, the model parameters have to be estimated from data collected at the patient's bedside. This work considers a seven-parameter model of the cardiovascular system and investigates whether these parameters can be uniquely determined using indices derived from measurements of arterial and venous pressures, and stroke volume. Methods: An error vector defined the residuals between the simulated and reference values of the seven clinically available haemodynamic indices. The sensitivity of this error vector to each model parameter was analysed, as well as the collinearity between parameters. To assess practical identifiability of the model parameters, profile-likelihood curves were constructed for each parameter. Results: Four of the seven model parameters were found to be practically identifiable from the selected data. The remaining three parameters were practically non-identifiable. Among these non-identifiable parameters, one could be decreased as much as possible. The other two non-identifiable parameters were inversely correlated, which prevented their precise estimation. Conclusions: This work presented the practical identifiability analysis of a seven-parameter cardiovascular system model, from limited clinical data. The analysis showed that three of the seven parameters were practically non-identifiable, thus limiting the use of the model as a monitoring tool. Slight changes in the time-varying function modeling cardiac contraction and use of larger values for the reference range of venous pressure made the model fully practically identifiable. (C) 2017 Elsevier B.V. All rights reserved.

关键词： 录音   校园广播系统   实际应用   研究分析  

摘要： 录音与校园广播系统是学校进行集中教学和管理的重要手段,能有效维持师生日常生活秩序,显著提高了教学质量和管理水平,所以加强对录音与校园广播系统的实际应用分析具有广泛的现实意义。本文将就录音与校园广播系统的组成部分、应用分类、选择方式、有效利用、未来发展等具体方面进行剖析。希望通过我们的讨论能够提高校园信息化、智能化建设,推动现代教育体系的改革发展。

关键词： 中药学   核心课程   研究性教学模式   实践  

摘要： 为提高中药学专业核心课程授课教师的教学水平,在中药学专业核心课程中引入研究性教学模式,转变教师的教学观念,推进教学活动由"教"向"学"的转化。整个过程分为宣讲、教学设计、研究性教学模式演练、教学竞赛、研究性教学进课堂等五个阶段。研究性教学模式的实施活跃了教师的教学思想,提升了教师的教学能力,取得了显著效果。

关键词： 《全日制义务教育数学课程标准(实验稿)》   数学课程改革   《基础教育课程改革纲要(试行)》   征稿启事   展望   2001年   新课程改革   数学教育  

摘要： 2001年,随着《基础教育课程改革纲要(试行)》和《全日制义务教育数学课程标准(实验稿)》的颁行,我国的数学教育步入了“新课改时代”。新课程改革给我们带来了很多新思想、新理念,在改革过程中我们也进行了深入的思考、实践和探索。

关键词： 电影史   认知维度   影视批评  

摘要： 中外电影史这门课是影视类专业必修的核心课程。在中外电影史这门课程的教学中,笔者逐渐摸索出一套适合中国传媒大学南广学院学生的教学方式,总结了一些教学经验。因为中国传媒大学南广学院以培养传媒类应用型人才为目标,所以在课程教学中不应给学生灌输太多艰深的电影理论以及过于庞杂的影视知识。一切教学都应围绕增长本专业学生的见识,提升其认知水平和影视创作能力而展开,这门课也为学生接下来的影视专业课和影视创作课学习打下了坚实基础。本文将选取电影史素材,课堂所讨论问题的设置,在电影史教学中试引入影视批评模式三方面具体总结现阶段的教学经验。

关键词： 中级财务会计   课内实训   教学反思  

摘要： 课内实训是以理论课教学目标和内容为依托,设计相应的实践内容穿插在理论课中进行训练,在教学中实现理论联系实际,培养学生应用技能的实践环节。为增强学生实践能力,越来越多的高校教师开始实施课内实训。本文以"中级财务会计"课程为例,结合笔者课内实训的体会,从课内实训的重要性、方法介绍入手,提出避免将实训变成另一种习题训练、与理论课程教学内容密切结合、实训方法的选择、实训指导应授之以渔、加强实训管理与考核等总结与反思。