双边轮式斜拉桥悬索检测机器人设计与分析(英文)

为了检测斜拉桥圆柱形悬索内部钢丝情况,设计了一种新型的双边轮式悬索爬升机器人,简述了其机械结构及运动方式,建立了爬升模型,分析了其机构的静态特性,并以直径为139 mm的悬索为例给出了相关设计参数.为使机构在电路系统故障时能安全回收,提出了一种基于反电动势理论的安全节能回收方法,应用曲柄滑块驱动气缸设计了气体阻尼机构,以消耗机构下降时因重力作用产生的多余动能,并建立了机构数学模型来仿真下降速度.试验结果表明,所设计的机器人能携带3.5 kg重物沿直径为65～205 mm的悬索平稳运行,满足了悬索检测的实用要求.     

Kinematic and neuromuscular relationships between lower extremity clinical movement assessments*

Lower extremity injuries have immediate and long-term consequences. Lower extremity movement assessments can assist with identifying individuals at greater injury risk and guide injury prevention interventions. Movement assessments identify similar movement characteristics and evidence suggests large magnitude kinematic relationships exist between movement patterns observed across assessments; however, the magnitude of the relationships for electromyographic (EMG) measures across movement assessments remains largely unknown. This study examined relationships between lower extremity kinematic and EMG measures during jump landings and single leg squats. Lower extremity three-dimensional kinematic and EMG data were sampled from healthy adults (males = 20, females = 20) during the movement assessments. Pearson correlations examined the relationships of the kinematic and EMG measures and paired samples t-tests compared mean kinematic and EMG measures between the assessments. Overall, significant moderate correlations were observed for lower extremity kinematic (r_avg = 0.41, r_range = 0.10–0.61) and EMG (r_avg = 0.47, r_range = 0.32–0.80) measures across assessments. Kinematic and EMG measures were greater during the jump landings. Jump landings and single leg squats place different demands on the body and necessitate different kinematic and EMG patterns, such that these measures are not highly correlated between assessments. Clinicians should, therefore, use multiple assessments to identify aberrant movement and neuromuscular control patterns so that comprehensive interventions can be implemented.     

The collision forces and lower-extremity inter-joint coordination during running

The purpose of this study was to compare the lower extremity inter-joint coordination of different collision forces runners during running braking phase. A dynamical system approach was used to analyse the inter-joint coordination parameters. Data were collected with six infra-red cameras and two force plates. According to the impact peak of the vertical ground reaction force, twenty habitually rearfoot-strike runners were categorised into three groups: high collision forces runners (HF group, n = 8), medium collision forces runners (MF group, n = 5), and low collision forces runners (LF group, n = 7). There were no significant differences among the three groups in the ankle and knee joint angle upon landing and in the running velocity (p > 0.05). The HF group produced significantly smaller deviation phase (DP) of the hip flexion/extension-knee flexion/extension during the braking phase compared with the MF and LF groups (p < 0.05). The DP of the hip flexion/extension-knee flexion/extension during the braking phase correlated negatively with the collision force (p < 0.05). The disparities regarding the flexibility of lower extremity inter-joint coordination were found in high collision forces runners. The efforts of the inter-joint coordination and the risk of running injuries need to be clarified further.     

基于缓冲区理论对高速公路进出口土地利用的分析——以四川省内江市为例

内江市地处四川盆地中部,位于成渝、内宜、隆纳和成自泸赤等高速的交点,交通极为便利。内江城市化进程加快,耕地逐年减少,通过建立缓冲区模型,在高速公路的进出口进行规模化、专业化和商品化的集约农业生产,挖掘土地潜力,改变单一的生产模式,可提高土地利用的综合经济效益。     

以谈促变：克林顿政府对朝政策回顾与评估

克林顿政府在处理朝鲜核与导弹问题上采取了接触包容、以谈促变的政策,其对朝政策实施效果可谓得失参半。虽然暂时冻结了朝鲜的核与导弹发展、初步改善了几度紧张的美朝关系,但是,由于对朝战略判断失准、国内政治因素牵制,不仅没有根本解决朝鲜的核与导弹问题,美朝关系正常化也未能实现。总体而言,克林顿政府对朝政策只是取得了可以逆转的有限成功。不过,这些成功经验却值得奥巴马殷鉴。     

两性物质配制缓冲溶液可行性研究

从理论和实验两方面探究了用一种两性物质配制缓冲溶液的可行性。选取3类(多元酸的酸式盐、弱酸弱碱盐、氨基酸)共7种常用两性物质,逐一测定其抗酸、抗碱能力,绘制β-pH曲线,并与通过理论计算得到的β-pH曲线对比。结果表明:两性物质作为酸时的酸解离常数Ka和两性物质作为碱时其共轭酸的酸解离常数Ka′比较接近,pKa的差值较小时,该两性物质可以单独配制缓冲溶液。     

H.264视频编码器在DSP芯片的实现

H.264标准的提出满足日益增长的视频应用对运动图像更高的压缩性能的需要,极大地降低了发送视频图像所需要的带宽,适用于多样化的网络环境。采用TMS320DM642实现H.264编码器是一种快速有效的方法,具有多视频处理功能、接口丰富、算法灵活和可根据视频信号处理的特点进行优化等优点。本文主要论述了采用TMS320DM642芯片实现H.264视频编码器的硬件设计及在DSP/B IOS操作系统中实现H.264编码器的软件设计,本系统设计的编码器能够脱离计算机,实现CIF格式视频流的实时编码。     

TUXEDO中间件中FML32缓冲区的应用研究

为解决通讯数据结构的动态构造问题,介绍了TUXEDO中间件的FML32缓冲区及其封装的应用事务管理接口ATMI,并结合银行代收话费系统中通讯结构构造的应用实例,阐述了FML32缓冲区的开发实现机制,对研究TUXEDO在三层模型中的应用开发提供了参考。     

基于风险传递的项目型供应链风险控制研究

在分析了项目型供应链的特点及其工期风险传递原理的基础上,根据关键链的缓冲思想,将项目缓冲重新分解并插入到供应链的环节中。算例证明,将项目缓冲插入到供应链的各环节中,对于项目供应链的风险传递性起到了抑制的作用,对项目整体的风险管理是有益的。     

视觉认知任务介入时踝关节稳定程度对纵跳落地模式影响的研究

目的:探讨视觉认知任务介入时不同踝关节稳定程度对纵跳落地姿势稳定策略与神经肌肉控制的影响。方法:36名男性高水平运动员,年龄(20.23±2.05)岁,按照踝关节稳定程度分为健康组(CON)、隐患组(LAT)和不稳定组(CAI),每组12人;随机顺序执行视觉认知任务及高台落地纵跳,并以单因素方差分析和Scheffe法比较各组在落地阶段的运动学、动力学及肌电参数。结果:(1)重心前后移动范围(CAI&LAT>CON)、垂直和整体稳定指数(CON>CAI)差异显著;(2)落地瞬间的踝(CAI>CON)、膝外翻(CON>LAT&CAI)、髋屈曲(CON&LAT>CAI)髋外展(CAI>CON)角度差异显著;下蹲最低点时,踝跖屈角度(CON>LAT&CAI)差异显著,踝屈伸(CON&LAT>CAI)和内外翻(CAI>CON&LAT)活动范围、踝内翻角速度峰值(CAI>CON)显著不同;(3)50 ms落地负荷率(CON>CAI)显著不同;(4)落地前期胫骨前肌(TA:CAI>LAT&CON)、腓骨长肌(PL:CON>CAI)、内侧腓肠肌(MG:CAI>CON)差异显著;落地瞬间股直肌(RF:LAT>CON&CAI)、PL(CON>LAT&CAI)、MG(CAI>CON)显著不同;下蹲期臀中肌(GM:CON>CAI)、PL(CON>LAT&CAI)、MG(CAI>CON)达显著差异,而BF/RF(CON>LAT&CAI)、S/TA(CAI>LAT&CON)、MG/TA(CAI&LAT>CON)共同收缩率差异显著;推蹬期GM(CON>CAI)、股内侧肌(VM:CON>CAI)、股二头肌(BF:CON>LAT&CAI)、比目鱼肌(S:CON>CAI)差异显著,而TA/S(CON>CAI)共同收缩差异显著;稳定期VM(CON>LAT&CAI)、S(CON>CAI)显著不同。结论:髋关节屈曲与外展、较多踝关节外翻与肌肉共同收缩是踝关节不稳定运动员稳定关节的重要机制,而较早且快速的踝关节内翻速度是导致踝关节不稳定运动员反复扭伤的关键因子;可通过强化臀中肌提升髋外展能力,同时训练腓骨长肌以提升踝关节保护的效果。