Stress analysis of anisotropic thick laminates in cylindrical bending using a semi-analytical approach

Semi-analytical elasticity solutions for bending of angle-ply laminates in cylindrical bending are presented using the state-space-based differential quadrature method (SSDQM). Partial differential state equation is derived from the basic equations of elasticity based on the state space concept. Then, the differential quadrature (DQ) technique is introduced to discretize the longitu- dinal domain of the plate so that a series of ordinary differential state equations are obtained at the discrete points. Meanwhile, the edge constrained conditions are handled directly using the stress and displacement components without the Saint-Venant principle. The thickness domain is solved analytically based on the state space formalism along with the continuity conditions at interfaces. The present method is validated by comparing the results to the exact solutions of Pagano’s problem. Numerical results for fully clamped thick laminates are presented, and the influences of ply angle on stress distributions are discussed.     

固支Mindlin 板弯曲问题的辛本征解

Hamiltonian system for the problem on clamped Mindlin plate bending was established by introducing the dual variables for the generalized displacements in this letter. By separation of variables, the transverse eigen-problem was derived based on the sympletic geometry method. With the solved sympletic eigen-values, the generalized sympletic eigen-solution was derived through eigenfunction expansion. An example of plate with all edges clamped was given. The sympletic solution system was worked out directly from the Hamiltonian system. It breaks the limitation of traditional analytic methods which need to select basis functions in advance. The results indicate that the sympletic solution method could find its more extensive applications.     

锻炼与针刺组合对退行性膝关节炎微循环血流灌注量的影响

目的：锻炼与针刺组合对退行性膝关节炎微循环血流灌注量的影响。方法：研究对象40例随机分为2组，分别是针刺组（单纯针刺）和锻炼组（站桩与针刺组合），对其实验前后疼痛程度（VAS）、微循环血流灌注量（MBPU）及皮肤温度的变化进行检测分析。结果：两组实验后，VAS评分明显降低（P<0.01），锻炼组优于针刺组（P<0.05）；MBPU降低（P<0.01），锻炼组优于针刺组（P<0.05）；局部温度明显提高（P<0.05）。结论：锻炼与针刺组合可以明显缓解退行性膝关节炎的疼痛症状，降低局部微循环血流灌注量，提高皮肤温度；优于单纯针刺疗法。     

阶梯形变截面梁的弯曲变形

提出了计算阶梯形变截面梁弯曲变形的一种新方法．算例表明，本文方法和结果对静定和超静定梁均适用，并且计算简捷，便于应用．     

壮瑶药酒涂擦合药包熨烫配合中医护理治疗膝骨关节炎的临床疗效评价研究

目的:观察壮瑶药酒涂擦合药包熨烫配合中医护理治疗膝骨关节炎的临床疗效。方法:将符合纳入标准的81例膝骨关节炎患者随机分为对照组40例和治疗组41例,治疗组在对照组治疗的基础上加用壮瑶药酒涂擦合药包熨烫治疗并予相应护理。15次为一疗程,治疗1疗程后评定疗效。以视觉模拟评分法观察治疗前后肿痛情况,评价止痛效果,采用国家疗效标准评价近期疗效,结果:治疗组症状改善和临床疗效较对照组显著,差异有显著性(P0.05)。结论:壮瑶药酒涂擦合药包熨烫配合中医护理治疗膝骨关节炎较单纯西药疗效显著。     

大型集装箱船的总纵强度实用计算方法

以我国１９９６年《钢质海船入级与建造规范》对大型集装箱船的总纵强度的要求为标准,讨论了具体装载状态下船舶总纵强度的校核方法,并着重探讨了在资料不完整的情况下与总纵强度校核有关的船舶资料的计算制作方法。     

Reproducibility of an isokinetic eccentric muscle endurance task

Abstract

Despite the widespread use of isokinetic eccentric muscle endurance protocols, no research has examined the absolute and relative reliability of such tests. The aim of this study was to examine the reliability of an isokinetic eccentric knee muscle endurance task. Fifteen healthy untrained males volunteered to take part in the study and written informed consent was obtained. The procedures received approval from the University Research Ethics Committee. Participants visited the laboratory on three separate occasions: 2 weeks before testing to familiarize them with the experimental procedures, and on two separate occasions, 2 weeks apart and at the same time of day. Isokinetic eccentric knee extension and flexion movements of the dominant limb were performed using a calibrated dynamometer (Biodex System 3). Range of motion during testing was set using voluntary maximal full extension (0 rad) to 1.57 rad of knee flexion and testing was conducted at 1.56 rad · s^?1. Participants performed four maximal efforts to determine maximal peak torque. After 2 min rest, participants completed the all-out endurance test of 50 continuous eccentric repetitions. Data were gravity corrected and windowed to only include constant velocity periods. Repeated-measures analyses of variance were used to examine differences in maximal peak extension and flexion torque and the maximal torque measurement recorded during the endurance test. Absolute and relative reliability of the torque fatigue index, work fatigue index, and total work were assessed through calculation of intra-class correlation coefficients, coefficients of variation, and absolute 95% limits of agreement using the methods described by Bland and Altman (1986). Differences between the strength test and the endurance trial for peak torque were found to be non-significant for both quadriceps (323 vs. 323 N · m) and hamstrings (183 vs. 178 N · m). The intra-class correlation coefficients revealed significant (P<0.05) positive moderate to strong correlations (r=0.44–0.94) across repeated trials for all parameters except hamstring torque fatigue (P=0.11) and hamstring work fatigue index (P=0.08). Coefficients of variation ranged from 6% to 48% and were large for the work fatigue index and torque fatigue index but acceptable for total work for both the extensors and flexors. The 95% limits of agreement indicated systematic bias in repeated trials for both the work fatigue index and torque fatigue index for extensors and flexors, ranging from ?3% to ?10%, with less fatigue evident in the second test. There was also systematic bias for total work, with more work being performed during the second than the first test for both extensors and flexors. The random error was large for all variables and there was greater random error in the hamstrings compared with the quadriceps. Together with moderate to strong intra-class correlation coefficients and large coefficients of variation, the data suggest that there is small systematic bias in repeated eccentric muscle actions for both the quadriceps and hamstrings, although the random error was large despite habituation procedures. Therefore, data from an isokinetic eccentric muscle endurance task should be viewed with some caution even when participants receive considerable habituation before assessment.     

Three-dimensional assessment of squats and drop jumps using the Microsoft Xbox One Kinect: Reliability and validity

The Microsoft Xbox One Kinect? (Kinect V2) contains a depth camera that can be used to manually identify anatomical landmark positions in three-dimensions independent of the standard skeletal tracking, and therefore has potential for low-cost, time-efficient three-dimensional movement analysis (3DMA). This study examined inter-session reliability and concurrent validity of the Kinect V2 for the assessment of coronal and sagittal plane kinematics for the trunk, hip and knee during single leg squats (SLS) and drop vertical jumps (DVJ). Thirty young, healthy participants (age = 23 ± 5yrs, male/female = 15/15) performed a SLS and DVJ protocol that was recorded concurrently by the Kinect V2 and 3DMA during two sessions, one week apart. The Kinect V2 demonstrated good to excellent reliability for all SLS and DVJ variables (ICC ≥ 0.73). Concurrent validity ranged from poor to excellent (ICC = 0.02 to 0.98) during the SLS task, although trunk, hip and knee flexion and two-dimensional measures of knee abduction and frontal plane projection angle all demonstrated good to excellent validity (ICC ≥ 0.80). Concurrent validity for the DVJ task was typically worse, with only two variables exceeding ICC = 0.75 (trunk and hip flexion). These findings indicate that the Kinect V2 may have potential for large-scale screening for ACL injury risk, however future prospective research is required.     

采用非对称渐开线齿轮减少齿根应力的研究

为了减小齿轮的齿根弯曲应力,提高齿轮的传动能力,本文根据非对称渐开线齿轮研究学者提出的齿廓方程构建思路进行了建模,并用NISAⅡ进行了齿轮应力变化的有限元分析。通过分析比较得出使用非对称渐开线齿轮可以提高齿轮的弯曲强度从而提高齿轮的传动能力。     

北京市高校篮球运动员膝关节损伤的调查研究

通过对北京市高校篮球运动员进行问卷调查,对运动员膝关节的损伤种类、损伤技术动作及损伤致因等方面进行了细致的调查研究,发现北京市大学生篮球运动员的膝关节损伤主要为半月板损伤、侧副韧带损伤、十字韧带损伤和髌骨损伤;造成其膝关节损伤的三种重要的原因是:准备活动不充分、自我保护意识差与运动负荷过大.