A／D转换技术及其在电力生产中的应用     

王彪 《合肥联合大学学报》2002,12(3):107-112

A／D转换器是电力系统微机保护电路、RTU模拟量遥测信息采集电路中的关键部件。并行比较型、逐次逼近型、双积分型A／D转换方案的转换电路不同．它们的主要技术指标、适用场合也有所差别。目前。在电力系统微机保护电路、模拟量遥测信息采集电路中采用的A／D转换芯片主要是AD574。  相似文献   

Fuel Burning Rate Model for Stratified Charge Engine     

宋金瓯姜泽军  姚春德王洪夫 《天津大学学报(英文版)》2006,12(3):169-173

A zero-dimensional single-zone double-curve model is presented to predict fuel burning rate in stratified charge engines, and it is integrated with GT-Power to predict the overall performance of the stratified charge engines. The model consists of two exponential functions for calculating the fuel burning rate in different charge zones. The model factors are determined by a non-linear curve fitting technique, based on the experimental data obtained from 30 cases in middle and low loads. The results show good agreement between the measured and calculated cylinder pressures, and the deviation between calculated and measured cylinder pressures is less than 5%. The zero-dimensional single-zone double-curve model is successful in the combustion modeling for stratified charge engines.  相似文献   

The representation and attainment of students with dyslexia in UK higher education   总被引：1，自引：0，他引：1  

Richardson  John T.E.  Wydell  Taeko N. 《Reading and writing》2003,16(5):475-503

Using a database of allstudents in higher education in the UK in1995–1996, students with dyslexia and those withno reported disability were compared in termsof demographic properties, programmes of studyand academic attainment. Students with dyslexiaconstituted 0.42% of all students resident inthe UK. Their representation varied with age,gender, ethnicity and entrance qualificationsand with their level, mode and subject ofstudy. Students with dyslexia were more likelyto withdraw during their first year of studyand were less likely to complete theirprogrammes of study, although with appropriatesupport the completion rate of students withdyslexia can match that of students with nodisabilities. In addition, students withdyslexia who completed first-degree programmestended to gain a poorer class of honours thanstudents with no reported disability, but 40%obtained first-class or upper second-classhonours. In short, dyslexia may havedeleterious consequences for progression,completion and achievement in higher education,but it is by no means incompatible with a highlevel of success, given appropriate commitmenton the part of the students and appropriateresources on the part of their institution.  相似文献   

温度和pH值对大球盖菇菌丝生长的影响   总被引：1，自引：0，他引：1  

何华奇  曹晖  潘迎捷 《安徽科技学院学报》2004,18(1):42-45

本文对大球盖菇菌丝生长的温度和pH值进行了研究,结果发现供试菌株在5-35℃范围内菌丝都可以生长,但不同温度条件下菌丝生长速率不同,最适生长温度为25℃.菌株在培养基pH5-pH11范围内都可以生长,大部分菌株最适生长pH值为7.  相似文献   

高等院校评价教师系统框架之数据来源分析     

郝春林  高俊玉 《教育教学论坛》2020,(13):26-27

高校评教是高校教育教学管理中的重要一环。文章针对目前已有的评教系统数据源单一、数据使用不充分、教师反馈不及时、师生互动性欠佳、学生评教积极性不高等现状,提出了一个高校评教系统新框架,以评教结果的使用范围为目的,反推出评教数据来源应具备多次性和多样性。每学期多次评教,实现教师与学生的互动,促进学生评教积极性,促进教师及时改进教学方法。评教人员除了学生之外,还应包括督导专家和往届生。  相似文献   

An Improvement of MPEG-4 Rate Control Algorithm     

鲁照华李华  刘继兴 《天津大学学报(英文版)》2005,11(1):40-43

Frame skipping in low bit video coding could significantly reduce the visual quality of reconstructed video. At the same time, if the complexity of the video sequence remains high for a long period, then driving up the long term average bit rate, the only resort of MPEG-4 Q2 rate control algorithm results in using a high quantization scale, which shows a poor visual quality of the reconstructed video. This paper analyzes the main causes of frame skipping in current MPEG-4 frame rate control scheme, and presents a new rate control algorithm based on the quadratic R-D model over a CBR channel. Key features of the present work are. 1) the bits allocated to each P-frame or B-frame are in proportion to its distance from the end of this GOP, i.e. more bits are allocated to the frames that are nearer to their reference Ⅰ -frame: 2) the target buffer level is changeable in the GOP, at the end of each GOP( five P-frames or B-frames), the target buffer level is linearly reduced from 1/2 to 1/4 of buffer size, to other frames, the target buffer level is set to 1/2 of buffer size: 3 ) a selective and judicious use of the reduced resolution mode, in addition to a modulation of the quantization scale parameter, is to control the average long term bit rate. Experimental results with different video sequences of varied complexity, encoded at low bit rates show better efficacy of the proposed algorithm than MPEG-4 Q2 rate control scheme, and the experimental results also show that the improved algorithm has significantly reduced the number of frame skipping, increased the overall PSNR, and improved the perceptual quality.  相似文献   

国有商业银行如何应对利率市场化改革的风险   总被引：1，自引：0，他引：1  

冯友钊  贺建清 《衡水学院学报》2004,6(3):44-46

利率市场化改革给国有商业银行的经营带来更大的风险,如:竞争风险、信用风险、利率风险、流动性风险等。如何趋利避害,应对风险,笔者认为从4个方面入手:产权制度改革;经营观念的转变;业务上由传统业务向中间业务、表外业务转变,由分业经营向混业经营转变;风险的全面管理。  相似文献   

福建省科技进步贡献率的测算和结果分析     

王倩  胡日东 《三明学院学报》2004,21(2):143-148

应用索洛余值法对福建全省经济增长及科技进步贡献率进行测算,计算出科技进步和其他要素对经济增长的贡献份额,并对各地市的数据进行横向比较,得出福建省各地市科技进步的差距。  相似文献   

有机物料施用量对土壤CO_2排放速率的影响   总被引：1，自引：0，他引：1  

严红  魏湜  张雷  夏国芳  戴先锋  王帆 《大连大学学报》2005,26(4):46-50

本试验选用有机碳含量不同的黑土,研究了有机物料施用量对土壤CO2排放速率的影响.研究表明,施用有机物料以后CO2排放速率明显增加,5%和3%处理CO2排放速率增加幅度显著高于2%和1%处理.有机碳分解初期CO2排放速率增加较快,波动性大,后期趋于稳定,其相对值大小随有机物料施用量及土壤有机碳含量增加而增加,即6号土>5号土>4号土>1号土.3号土性质与其它土壤样品略有不同,CO2排放速率偏高.  相似文献   

“双一流”建设背景下高等教育高质量发展指标研究     

张丽 《天津市教科院学报》2021,(2):43-49

创新驱动高质量发展是高等教育发展的未来,也是“双一流”建设质量发展指标研究的关键。在筛选和找出“双一流”建设质量的关键绩效指标(KPI)的基础上,提出了三个步骤的技术路线:一是分析影响因素,且按其重要性进行排列;二是按重要程度不同而精选出关键影响要素和绩效指标;三是更加重视整体研究和相关性研究,促进“以评促建”功能的实现。最后,对其中几个关键绩效指标(KPI)进行较为详细的诠释,包括高等教育毛入学率、生师比、学术声誉调查等。  相似文献