排序方式： 共有84条查询结果，搜索用时 0 毫秒
1.
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
2.
信号与系统课程是电子信息类专业的核心基础课程,在各种经典教材中都采用冲激响应匹配法求解微分方程零时刻的跳变值。本文分析了冲激响应匹配法求解跳变问题存在的问题,提出了一种应用laplace变换求解跳变问题的新方法,简述了此种方法的原理和求解过程。多年的教学经验表明这种方法更简单,更易让学生掌握。 相似文献
3.
郭茂政 《唐山师范学院学报》2003,25(5):18-19
通过对绕桩绳索摩擦力的分析，进一步说明在摩擦系数一定的情况下，正压力是决定最大静摩擦力(或滑动摩擦力)的唯一因素。 相似文献
4.
选取陕西师范大学24名非体育专业本科生为实验对象,设置实验组和对照组,研究跳绳运动对踝关节位置觉的影响,为在各种体育项目中的踝关节训练以及跳绳运动本身的比赛和训练提供理论依据。方法：将24名同学按照性别与组别均等分为实验组（n=12）和对照组（n=12）,实验组跟随陕西师范大学跳绳俱乐部进行为期16周的跳绳训练,对照组在试验期间不参加任何体育俱乐部。结果：女生实验前后左踝可变误差存在显著性差异（P＜0.05）,其它无显著性差异（P＞0.05）。但实验后实验组踝关节位置觉优于对照组,说明跳绳运动对踝关节位置觉的锻炼有一定积极意义。 相似文献
5.
根据已知提升机和提升钢丝绳型号,对平衡尾绳进行选型。包括钢丝绳结构选择、抗拉强度选择、等重尾绳的选择。本文还针对在选取不到等重尾绳的情况下,对轻尾绳和重尾绳的选取进行比较和分析。 相似文献
6.
This study compares the instrumentation and analysis techniques used when determining the power expended pedalling a rope-braked
ergometer manufactured by Monark (Sweden) during a low intensity test. Power values were generated by eight subjects. The
instrumentation consisted of load cells to measure the rope brake forces, a tachometer to measure the flywheel velocity and
instrumented pedal cranks manufactured by Schoberer Rad Messtechnik (SRM). The subjects pedalled a rope-braked ergometer at
60 rev min-1, against a resistance of 3 kg, for 5 minutes. Three different measurements of the mean power were recorded and these were
compared with the value given by Monark. The SRM cranks provided two sets of results using different software packages supplied
with the cranks. SRM standard software is used for taking measurements during training and cycle races over long time periods.
An additional piece of software is provided by SRM called Ptnew, which gives readings of torque and pedal cadence over periods
up to 30 seconds. Using the values supplied by Monark each subject generated 180 W of power. The mean power for the eight
subjects, measured using the SRM cranks, was 170.36 W (SD 4.11) using the alternative SRM software (Ptnew) over a 30 second
period and 173.68 W (SD 2.21) using the standard SRM software. From the direct measurement of the brake forces and flywheel
velocity the mean power across the eight subjects was 148.90 W (SD 5.89). The SRM cranks measure the input power, whereas
the direct measurement system measures the power output excluding mechanical losses. These values give a figure for the mechanical
efficiency for the roped-braked ergometer of 88%. It was found that Monark overestimates the power generated by the subjects
when compared with both the SRM systems and the direct measurement instrumentation. 相似文献
7.
我国篮球运动员跳投技术发展的潜在空间 总被引：2，自引：0，他引：2
从人体运动技术科学原理角度阐述了决定跳投技术完善程度的三大技术性指标，描绘了现代篮球比赛跳投技术的合理化模式，并分析了我国篮球运动员跳投技术发展的潜在空间。 相似文献
8.
大学生“逃课族”现象日益加剧,严重冲击着高校现有的和谐教学秩序,危害着大学生综合素养和专业技能的培养。结合大学生教育管理工作实际,通过调查“逃课族”群体现状,分析其产生的深层原因,从服务态度、管理制度、人格培养等方面提出教育建议。 相似文献
9.
李尚华 《晋城职业技术学院学报》2010,3(2):43-45
跳绳项目在我国乃至全球,是一项历史悠久、方便快捷、喜闻乐见的的健身健心运动。目前,随着国家《学生体质健康标准的》的颁布与实施,对高校大学生的体质状况得以有效的掌握,学校体育教学改革不断深入,虽然学生的体质呈逐年上升趋势,但是整体水平偏低,跳绳项目的充分发掘与开展,应用于实践,能够适应师生的不同需要,有利于目前在校大学生体质健康状况的改善． 相似文献
10.
在500kV鲲东甲乙线改造工程中,采用旧导线置换导引绳的方法,减少了人工展放导引绳的工作量,且有效克服了地形条件恶劣、工期紧、青赔难度大的特点,取得了良好的经济效益和社会效益。本文对上述施工中的旧导线置换导引绳技术,阐述其作业步骤及其关键技术要点,希望对于以后类似的改造工程有积极的指导作用。 相似文献