A channel distortion model for video over lossy packet networks     

Cheng Jian-xin  Gao Zhen-ming  Zhang Zhi-chao 《浙江大学学报(A卷英文版)》2006,7(1):48-53

Error-resilient video communication over lossy packet networks is often designed and operated based on models for the effect of losses on the reconstructed video quality. This paper analyzes the channel distortion for video over lossy packet networks and proposes a new model that, compared to previous models, more accurately estimates the expected mean-squared error distortion for different packet loss patterns by accounting for inter-frame error propagation and the correlation between error frames. The accuracy of the proposed model is validated with JVT/H.264 encoded standard test sequences and previous frame concealment, where the proposed model provides an obvious accuracy gain over previous models.  相似文献   

Effects of environmental intervention on sedentary time,musculoskeletal comfort and work ability in office workers     

Ying Gao  Nina Nevala  Neil J. Cronin  Taija Finni 《European Journal of Sport Science》2016,16(6):747-754

Sit–stand workstations offer a potential strategy to reduce prolonged occupational sitting. This controlled intervention study examined the effects of an environmental intervention on occupational sedentary time, musculoskeletal comfort and work ability, and the usability of sit–stand workstations in office work via a self-reported questionnaire. The intervention group (n?=?24) used sit–stand workstations during the 6-month intervention period, and the control group (n?=?21) used traditional sitting workstations. The results showed that working at sit–stand workstations can reduce sitting time significantly compared to control workstations (?6.7% vs. 5.0%, p?=?.019), which is reallocated mostly to standing (r?=??0.719, p?p?=?.028), as well as work ability (p?=?.022). The majority of intervention subjects rated sit–stand workstation adjustability as good (83.3%), and 75.0% were satisfied with the workstation. About 41.7% of the intervention participants, who were exclusively female, used the sit–stand function on a daily basis. While the environmental change alone was effective, it is likely that promoting the daily use of sit–stand workstations with counselling would lead to even more substantial positive effects.  相似文献   

关于现行监理制实施的探讨     

李春前  齐伟军  高宏琴 《鸡西大学学报》2001,(4)

针对工程建设监理实施中存在的问题,提出当前监理工作的对策和工作模式.  相似文献   

氢化丁腈橡胶的应用与研究进展   总被引：8，自引：0，他引：8  

尹海川  韦薇  高诚伟 《楚雄师范学院学报》2002,17(3):61-62

本文评述了氢化丁腈橡胶（HNBR）的应用及进展，指出了我国发展氢化丁睛橡胶的潜力。  相似文献   

Study on pig growth hormone gene polymorphisms in western meat-type breeds and Chinese local breeds     

宋成义  高波  经荣斌  陶勇  毛九德 《浙江大学学报(A卷英文版)》2003,4(6):734-739

Chinese Meishan and Jiangquhai pigs are two of the most prolific pigs in the world, but their growth rate is lower than that of Duroc, Landrace and Pietrain pigs. It is suggested that growth rate is regulated by growth hormone. The objective of the current study was to analyze the porcine growth hormone (pGH) gene polymorphisms based on the polymerase chain reaction restriction fragment-length polymorphism method (PCR-RFLP) for three western meat-type breeds (Duroc, Landrace and Pietrain) and two local Chinese pigs (Meishan and Jiangquhai). Five polymorphic restriction sites were detected with the ApaI, MspI, BspI and HhaI restriction enzymes in two amplified fragments (605 bp, -119 to +486; 506 bp, +206 to +711). Breed difference was found only in the 506 bp fragment. There was no difference in allelic frequencies of BspI and HhaI restriction sites among the five breeds (P>0.05). Landrace and Meishan pigs lacked allele G3 of MspI site. The allele G3 frequency of restriction MspI site of the 506 bp fragment in Pietrain pigs was higher than that in Duroc and Jianquhai pigs (P<0.001). For ApaI site, the Meishan pigs lacked allele G1; no difference was found in allelic frequencies among Pietrain, Duroc, Landrace and Jiangquhai pigs (P>0.05). This new and rapid PCR-RFLP typing method is an attractive tool for analysis of porcine growth hormone gene restriction sites. The differences in MspI and ApaI restriction sites may explain the growth difference between the foreign meat-type breeds above mentioned and local Chinese pigs.  相似文献   

教学仪器订购系统设计     

高卫东  王国先  胡文汉 《中国教育技术装备》2003,(9):1-3

介绍了一种为中小学校进行教学仪器、器材、设备的订购、配备及管理的计算机管理软件系统，对其主要功能、数据库表、操作性能、用户界面、编程方法等作了扼要说明。  相似文献   

美国与加拿大中小学教师评估政策比较与评析     

陈弘  高惠蓉 《外国中小学教育》2007,(2):26-28,32

美国与加拿大两国在教师职业能力的培养上各有千秋,但两国都将教师评估政策的制定和实施摆在国家教育改革的重要位置。两国都将教师的评估过程贯穿于教师的全部教育及职业生涯,从而实现中小学学校教学的不断重塑。上述的教师评估计划的动因是两国政府所倡导的公共教育责任制的要求。本文将以对两国的教师评估实践和进程进行比较性的评述,来探讨国外中小学教师评估政策和体系实施的原因、意义和影响以及未来改进的方向。  相似文献   

市场驱动--我国高等教育改革发展的鲜明特征   总被引：1，自引：0，他引：1  

付勇  高阳 《高教探索》2003,(4):20-22

10多年的高等教育改革贯穿了一条清晰的主线 :以市场为导向 ,以市场为标准来发展和检验我国的高等教育。本文分析了促使高等教育面向市场的客观环境 ,探讨了市场经济基本原则在高教中的广泛运用和市场驱动的两层含义  相似文献   

俄罗斯中等职业教育的现状及发展趋势   总被引：2，自引：0，他引：2  

高凤兰  曲志坚 《外国教育研究》2005,32(9):46-49

俄罗斯中等职业教育是国家教育体系中一个重要的组成部分。中等专业学校是国家经济发展中普通技术人才的主要培养基地，20世纪90年代，中等职业教育经历了重大变革，近些年来有了稳步的发展。分析、研究俄罗斯中等职业教育的现状，并在此基础上预测俄罗斯中等职业教育的发展趋势，对我国中等职业教育的发展将有一定的启示和借鉴。  相似文献   

Numerical investigation of cavitating flow behind the cone of a poppet valve in water hydraulic system   总被引：2，自引：0，他引：2  

高红  傅新  杨华勇  Tsukiji Tetsuhiro 《浙江大学学报(A卷英文版)》2002,3(4):395-400

Computational Fluid Dynamics (CFD) simulations of cavitating flow through water hydraulic poppet valves were performed using advanced RNGk-epsilon turbulence model. The flow was turbulent, incompressible and unsteady, for Reynolds numbers greater than 43000. The working fluid was water, and the structure of the valve was simplified as a two dimensional axisymmetric geometrical model. Flow field visualization was numerically achieved. The effects of inlet velocity, outlet pressure, opening size as well as poppet angle on cavitation intensity in the poppet valve were numerically investigated. Experimental flow visualization was conducted to capture cavitation images near the orifice in the poppet valve with 30° poppet angle using high speed video camera. The binary cavitating flow field distribution obtained from digital processing of the original cavitation image showed a good agreement with the numerical result. Project supported by the National Natural Science Foundation of China (No. 59835160) and Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry of China (No. 50175097)  相似文献