水流掺气对明流泄洪洞及挑坎水力特性的影响

水流充分掺气可以避免高流速泄洪设施发生空蚀,但也会改变相关水力特性。通过对某大坝泄洪洞掺气设施水力模型试验及关于水流表面自掺气发生条件的相关分析,提出了在全程流速超过38 m/s,长度达550 m的明流洞内仅布置一级掺气设施的建议,较通常情况减少了两级;并针对泄洪洞出流方向与河道流向交角达60°的特点,研究提出了一种大差动异型鼻坎消能工。水工模型试验成果表明,其挑流水舌沿河道纵向扩散良好,水舌外缘与河道对岸保持了30 m以上的安全距离。该泄洪洞建成后经历了高水头、较长时间的泄洪运行,明流洞和鼻坎消能工均无空蚀发生,但挑坎水舌却冲刷到对岸边坡。     

How social distance shapes human–robot interaction

This paper investigates how social distance can serve as a lens through which we can understand human–robot relationships and develop guidelines for robot design. In two studies, we examine the effects of distance based on physical proximity (proxemic distance), organizational status (power distance), and task structure (task distance) on people׳s experiences with and perceptions of a humanlike robot. In Study 1, participants (n=32) played a card-matching game with a humanlike robot. We manipulated the power distance (supervisor vs. subordinate) and proxemic distance (close vs. distant) between participants and the robot. Participants who interacted with the supervisor robot reported a more positive user experience when the robot was close than when the robot was distant, while interactions with the subordinate robot resulted in a more positive experience when the robot was distant than when the robot was close. In Study 2, participants (n=32) played the game in two different task distances (cooperation vs. competition) and proxemic distances (close vs. distant). Participants who cooperated with the robot reported a more positive experience when the robot was distant than when it was close. In contrast, competing with the robot resulted in a more positive experience when it was close than when the robot was distant. The findings from the two studies highlight the importance of consistency between the status and proxemic behaviors of the robot and of task interdependency in fostering cooperation between the robot and its users. This work also demonstrates how social distance may guide efforts toward a better understanding of human–robot interaction and the development of effective design guidelines.     

浅谈皮带定量给料机的机械配置选型

皮带定量给料机是目前水泥生产企业中最为常见的过程计量和配料的设备。作者结合多年来开发、调试和使用皮带定量给料机的实践经验与资料积累，介绍了如何根据实际需要和使用量程，通过对皮带定量给料机的主要机械参数的计算来合理地选用定量给料机的型号和规格。     

基于半监督距离学习的运动相似性度量算法

人体运动捕获技术的发展使得运动捕获数据不断积累,人体运动的检索技术成为运动数据管理和重用过程中的关键环节。由于逻辑相似的运动在数值上并不一定相似,使用欧式距离度量2个运动间的逻辑相似性难以取得理想的结果。为此,提出一种半监督的距离度量学习算法,利用带标记的运动和未标记运动进行训练以得到运动间的马氏距离度量,从而判断2个运动之间的逻辑相似性,实现运动检索。实验结果表明,与现有的大部分检索算法相比,该算法能够得到更高的查询精度,且没有任何人工干预,可应用于自动检索领域。     

Euclidean Distance Mapping for computing microstructural gradients at interfaces in composite materials

This paper presents an image analysis procedure using Euclidean Distance Mapping to compute microstructural gradients at interfaces in composite materials. This method is capable of producing phase distribution plots at single pixel strip width very quickly and efficiently. Compared to conventional dilation-subtraction strip analysis, the new method is faster, more flexible and is not constrained by feature geometry and boundary conditions. This allows for truly random and unbiased sampling. The new method was applied to investigate microstructural gradients at the interfacial transition zone (ITZ) of an ordinary Portland cement concrete. The average results show strong gradients in anhydrous cement and detectable porosity at the ITZ, but this is highly variable from location to location. The overall ITZ characteristics depend on the amount of calcium hydroxide deposited on aggregate particles. The new method was able to measure the effect of these calcium hydroxide deposits on the porosity gradient, which has not been reported before.     

搅拌设备设计的几点体会

从搅拌轴的支承条件、轴承间最佳距离的确定以及搅拌轴的稳定器等几个方面讨论 ,分析了其对搅拌设备设计的影响 ,并提出了相应的措施和方法。     

准完全最大距离伪随机测试研究

对超大规模集成电路进行随机测试的测试码之间的距离作了定量分析,在此基础上,改进了最大距离随机测试算法中测试码的生成方法,使得所生成的伪随机测试码集合同时达到最大海明距离与近似最大笛卡尔距离。因此每一个测试码可以尽可能多地独立检测到更多不重复的故障。进而提出了准完全最大距离测试新算法的思想和构建理论,并详细阐述了该算法的执行流程。在ISCAS'85基准电路上进行的大量实验数据分析表明,本方法确实有效地提高了随机测试效率,降低了随机测试成本。     

基于面向分类准则的维数约简及其在人脸识别中的应用

针对高维数据导致的维数灾难问题,提出了一种基于面向分类准则的维数约简方法。所提准则使每个训练样本在特征空间中与同类样本尽可能接近,而与异类样本尽可能疏远。首先对每个训练样本定义同类样本加权平均距离和异类样本加权平均距离。然后基于上述两个概念分别定义总体同类距离和总体异类距离。以最小化总体同类距离和最大化总体异类距离为目的提出了面向分类的准则(Classification Oriented Criterion,COC)。最后,基于面向分类的准则推导出了一种新的维数约简方法。在公共人脸数据库ORL和Yale上的实验表明所提方法性能优于有代表性的维数约简方法。     

一种基于混合量子粒子群的快速运动目标跟踪算法研究

量子粒子群算法在优化过程中需要权衡局部探索性和全局开拓性,进化后期由于全局开拓能力的丧失使得种群多样性减少,设计了一种基于欧式距离的混合量子粒子群算法,通过计算粒子的种群多样性,当种群多样性低于阈值范围时加入基于欧式距离的种群划分策略划分子种群,从而保证获得全局最优解。利用标准测试函数验证提出的混合量子群算法有效性。提出了基于混合量子粒子群的Mean Shift算法(HQPSO Mean Shift)完成目标快速跟踪,克服传统Mean Shift算法的在跟踪快速移动目标时出现"跟丢"的问题。     

Advanced underfill for high thermal reliability

The key to the success of flip‐chip technology lies in the availability of sucessful underfill materials. However, the reliability of flip‐chip technology using current underfill materials is generally found to be lower than that of conventional wire‐bond connection packaging materials such as epoxy molding compound (EMC) because of the high coefficients of thermal expansion (CTE) and moisture absorption of cured underfill material. In this study desbimide (DBMI), which has a low melting point (about 80°C), was used in the underfill materials as a cohardener. As a result, DBMI‐added underfill can show excellent thermal reliability, which is due to the superior properties of the CTE, the elastic modulus, and water resistance. When the properties of a 2 wt % DBMI‐added underfill were compared with those of a typical underfill (epoxy/anhydride), the CTE value was reduced to less than one‐half at the solder reflow temperature (about 200°C), the elastic modulus was reduced to less than one‐half in the temperature region below the glass‐transition temperature, and the water resistance was improved twofold. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2617–2624, 2002