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位平面编码(BPC)是JPEG2000编码器中EBCOT的重要组成部分。为了解决BPC实现的低效问题,提出了一种改进的并行硬件结构来实现字级位平面编码算法。对编码通道预测和上下文形成的流水线并行处理技术进行了研究,实现了在一个时钟周期内对一个条带列的所有位样本并行编码。当样本系数被顺次编码时,包含在每个位平面中的三个通道编码在一次扫描中完成。该系统结构已经通过ModelSim实现和TSMC综合。结果表明,该结构可以有效减少硬件成本,并提供高速的数据处理能力,适合实时图像和视频的应用。 相似文献
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在进行单训练样本人脸识别时,基于每人多个训练样本的传统人脸识别算法效果通常不太理想。尤其是基于Fisher线性鉴别准则的一些方法,由于类内散布矩阵为零矩阵,根本无法进行识别。针对以上问题进行了分析研究,提出了一种新的样本扩充方法,即:采用位平面图像分解法,将每幅样本图像分解为8幅,进而通过各种合成策略构造多幅样本图像。使用一种更加稳定的二维最大散度差线性鉴别分析方法(2DMSLDA)对上面获得的新样本图像进行特征抽取。在ORL国际标准人脸库上进行的实验表明了所提算法的可行性和有效性。 相似文献
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应用螺旋理论对并联机器人形位的分析与综合 总被引:3,自引:0,他引:3
采用螺旋理论对并联机器人的约束与运动问题进行了分析和总结. 在各种约束存在条件下,分析了刚体平台相应的运动轨迹形式,为今后对多刚体的形位分析提供了可行的理论依据. 相似文献
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为实现5自由度平面构型的双手爪爬杆机器人Climbot对目标杆件的自主抓夹,提出一种基于2D激光扫描测距仪的杆件位姿检测和自主抓夹方法.首先根据Climbot的平面构型,给出了机器人在两圆杆间过渡时的特殊位姿约束条件.再摆动夹持器使得安装在上面的激光传感器可以用扫描的方式获取目标杆件上若干中心点位置,并将其拟合出杆件的空间直线方程,即杆件位姿.并基于直线方程,规划出了满足过渡约束条件的自主抓夹运动.最后通过实验分析了杆件中心点位置的检测误差,以及所求杆件位姿相对于实际杆件和Climbot夹持器坐标系的角度误差.相对于杆件尺寸以及夹持器张合度,上述误差均可接受.本文方法能够准确地检测目标杆件的位置信息,并给出合理的抓夹运动规划. 相似文献
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Recommendation 60 of the Ladbroke Grove rail inquiry stated that “comprehensive market research in regard to safety related
measures should be carried out in order to take account of the views of informed passengers” (Cullen 2001, p. 235). In response, the Rail Safety and Standards Board Limited (RSSB) commissioned a survey of railway passengers nationwide,
to investigate passenger perceptions of risk and safety at stations, on platforms and on trains, and to research passenger
preferences for implementing safety interventions. Following qualitative interviews conducted with rail travellers, two separate
questionnaires were designed and piloted. Each survey was administered face-to-face at 15 hub railway stations nationwide,
according to a quota sample, and respondents were asked to return completed questionnaires by post. The overall response rate
was approximately one-third. The results of the safety and risk survey provide a valuable indicator of passenger perceptions
of risk, especially when compared to quantitative assessments of actual risk. The findings suggest that the relationship between
perceived and actual risk is not particularly strong. The data from the passenger preferences questionnaire were analysed
using conjoint techniques, and the results provide information on passenger preferences and priorities for improvement. The
results are likely to be of value to the railway industry in allowing passenger preferences to be taken into account when
implementing safety interventions. 相似文献
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<正> Ahera 在中国深圳、杭州、北京三地主办 SOPC World 2008,《电子技术应用》(AET)作为唯一的媒体对此次活动进行跟踪报道。针对目前一些热点问题及 Altera 的发展策略等,我们有幸在杭州对 Altera 亚太区副总裁兼董事总经理 ErhaanShaikh(柯汗青)先生进行专访。AET:您觉得与去年相比,今年贵公司及整个行业有什么改变吗?Shaikh 先生:与去年相比, 相似文献
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对主驾驶安全气囊静态点爆的前期阶段进行仿真,并结合实验进行验证.详细描述气囊压缩折叠方法和气囊压缩后的质量要求,分析影响仿真精度的因素并提出验证这些因素准确性的方法.结果表明测量支反力是验证气囊在展开过程中对周围零部件作用力的产生以及零部件间力传递过程是否准确的有效途径. 相似文献
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AbstractThe objective of this work is to demonstrate a method for examining the competing effects of secular trends in body size, seat size and configuration, and the increased load factor of aeroplanes. The method uses statistical modelling and virtual fit testing to provide a flexible environment for exploring the impact of various parameters on passenger accommodation. A case study demonstrates the method by exploring the effect of seat width on the accommodation of US civilians (based on seated hip breadth). The case study demonstrates that recent trends of decreasing seat widths and increasing load factors lead to higher disaccommodation. Based on anthropometry and virtual fit, women are also shown to be disproportionately disaccommodated compared to men.Practitioner summary: Airlines are reducing seat width at the same time that individuals worldwide are getting larger. Flights are increasingly crowded, with load factor at a record high. This paper explores the effects of seat width on passenger accommodation under several scenarios involving load factor, demographics, and passenger seating allocation strategies. 相似文献
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在水电厂水轮机检修过程中,水轮机导叶立面间隙调整是一项重要而精细的工作,其主要目的是将水轮机24片矩形导叶两两相靠,调整为一个密不透水的圆筒状。传统导叶立面间隙调整方法虽然能满足调整完成后两两导叶立面间隙为零的技术要求,但因缺乏精确的反馈量和监视量,调整过程费时费力,同时可能造成导叶之间压紧程度不一的现象,对后续调整产生一定影响。通过采集机组检修前导水机构各项数据,导入三维建模软件进行精确建模,在模型中进行多项初始条件下进行水轮机导叶立面间隙模拟调整,并与检修前数据比较,得出该检修状态下导叶的标准位置。在现场实际调整过程中,根据不同水轮机导叶立面间隙分布情况、机组检修级别,结合导叶标准位置提出差异化水轮机导叶立面间隙调整策略,极大提高了水轮机导叶立面间隙[3]调整效率和精度,保证了机组运行安全性。 相似文献
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随着列车运行速度的提高,高速客车横向稳定性一直是近年来研究的热点. 建立 9 自由度半车数学模型,利用数值方法对该系统的横向稳定性与分岔问题进行了研究,得到车辆系统发生蛇行运动时的临界速度及分岔后各运动状态的转变过程. 结果表明系统超过临界速度后会发生复杂的动力学行为,包括单周期、两周期、混沌运动等,并且由对称向不对称,最后再向对称运动转化. 相似文献
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Seat pitch, defined as the distance from a point on the back of one seat to the same point on the seat in front, is one of the most important factors influencing aircraft seating comfort. This study assessed the influence of different airline seat pitches on subjective ratings of discomfort and body-seat interface contact pressures. This was a laboratory within-subjects study using an aircraft interior mock up to vary seat pitch. Twelve participants completed 1 h of sitting in each of five different seat pitches (28inches, 30inches, 32inches, 34inches, and 36inches). Interface pressure mats measured seat and backrest pressure distribution, subjective rating scales were used to measure overall and local body region discomfort. The results showed that overall body and local body region discomfort ratings tend to be lower when the seat pitch increased from 28 inches to 36 inches (p < 0.05). For pressure variables, the upper back average contact area, upper/lower back average contact pressure, upper/lower back average peak contact pressure, right buttock average contact area, left/right thigh buttock average peak contact pressure, and left buttock average peak contact pressure were significantly affected by seat pitch(p < 0.05). Separate analyses support that seat pitch was more strongly correlated with backrest interface pressure than with seat pan pressure. In conclusion, seat pitch was found to be an important factor associated with body-seat contact pressure and discomfort ratings. 相似文献