A forward algorithm for prestressed construction process of large-span suspendome based on the equivalent pre-tension

To accurately simulate prestressed construction process of large-span suspendome, the initial state of construction process according to practical construction sequence is established, and the construction mechanical analysis for prestressed construction process is especially studied. Features of prestressed construction process of large-span suspendome are summarized, and the insufficiencies of the application of state variable superposition method, back analysis method, birth and death element method are analyzed. Combined with nonlinear finite element analysis method, forward algorithm for prestressed construction process based on the equivalent pre-tension is proposed, and the specific application method and procedure are given. Changzhou stadium steel roof engineering is taken as an example to verify the practicability and applicability of forward algorithm for prestressed construction process. The conclusion is that, using forward algorithm for prestressed construction process based on the equivalent pre-tension, the structure state of each construction phase can be accurately tracked, and the nonlinear contact of strut and rigid framework, interactive impact of cable force, conversion of temporary structure system, and structural geometric nonlinearity can be comprehensively considered.     

Linear and temporal stride characteristics of 3-day event horses at a CCI*** 3-day event horse inspection

Aims. To quantify the linear and temporal characteristics of the trot of 3-day event horses during the preliminary horse inspection of an advanced grade CCI*** 3-day event.

Methods. A cross sectional study was made of the kinematics of 24 3-day-event horses during the first horse inspection at a CCI*** level 3-day event. Video footage was digitised and linear and temporal measurements were made.

Results. The horses trotted for an average of 10.44 ± 1.55 strides. Spatial measurements were made on an average of 5.66 ± 0.92 consecutive strides when the horses were within the calibration zone. The horses increased and then obtained a constant velocity within the calibration zone. Trotting on the asphalt track did not alter the relationships between stride length, stride duration and velocity when compared with previously published values. Horse-specific differences in stance and retraction percentages were identified.

Conclusion. Horse specific differences were identified that may contribute to each horse's unique gait or “kinematic fingerprint”. It is proposed that the initiation of, and completion of, stance by the hind limb first may represent “engagement of the hind quarters” and be a response to dressage training.     

我国部分高校男子跳远运动员 助跑最后两步及起跳技术的运动学分析

通过文献资料法、专家访谈法、实验拍摄法以及数理统计法对2012年全国大学生运动会中国大学生男子跳远项目的前6名运动员助跑最后两步及起跳技术进行分析,结果表明：我国高校男子跳远运动员的助跑倒数两步步长和步速变化都没有达到理想范围,速度损失率多数没有达到理想范围;着板瞬间和起跳瞬间平均水平速度以及起跳瞬间平均垂直速度均低于我国优秀男子跳远运动员;起跳阶段各个关节角度的过小,使着地和离地瞬间的蹬伸、摆动不够积极充分;着板角和蹬地角较小,造成扇面角过大,使助跑接起跳的连贯性降低,不能够获得较好的起跳垂直速度。     

基于切点前方交会法的大型烟囱倾斜观测最佳方案设计

分析了切点前方交会对大型烟囱倾斜变形观测精度的影响,设计了实用的最佳交会图形,并通过实际工程运用,证明了提出的最佳方案的正确性。     

大直径开孔切割机构的设计与仿真

在圆柱壳体上切割大直径偏心圆孔和变角度坡口问题一直是机械加工中的一个难题。为此,按照切割孔和坡口的基本功能要求,运用串并联机构相结合,设计了具有5个自由度的新型切割机。该切割机可以完成在工作空间范围内的任意曲线加工。通过采用Pro/E和RecurDyn软件对切割机的运动学仿真,验证了所设计机构的合理性和良好的动态特性。     

民事诉讼中举证责任的内涵

民事诉讼中的举证责任具有双重内涵,即行为意义上的和结果意义上的举证责任,抑或提供证据责任和证明责任。证明责任是举证责任的本质所在,是提供证据责任的基础和内在动因,而提供证据责任则是证明责任的派生和表象。两者都是举证责任不可缺少的组成部分,提供证据责任是当事人对案件事实进行证明的前奏,证明责任是当事人在提供证据后的继续。     

Dynamic mobilisation exercises increase cross sectional area of musculus multifidus

Reason for performing study: In human subjects with back pain, the deep spinal stabiliser m. multifidus is inhibited ipsilaterally leading to atrophy, asymmetry and intervertebral instability. Specific physiotherapeutic exercises are required to reactivate m. multifidus. This study assesses the effect of dynamic mobilisation exercises on size and symmetry of m. multifidus in the equine caudal thoracic and lumbar spine. Hypotheses: Regular performance of dynamic mobilisation exercises over a period of 3 months increases cross sectional area (CSA) and left‐right symmetry of m. multifidus muscles in the caudal thoracic and lumbar spine. Methods: Eight horses performed dynamic mobilisation exercises (3 cervical flexions, one cervical extension and 3 lateral bending exercises to the left and right sides) with 5 repetitions/exercise/day on 5 days/week for 3 months during which time they were not ridden. Left and right m. multifidus CSA was measured ultrasonographically at 6 levels from T10 to L5 at the start (initial evaluation) and end (final evaluation) of the 3 month study. Changes in CSA of the right and left m. multifidus muscles and symmetry of m. multifidus CSA on the right and left sides between the 2 evaluations were sought using analysis of variance (P<0.05). Results: Between the initial evaluation and final evaluation m. multifidus CSA increased significantly at all 6 spinal levels on both right and left sides. Asymmetries in m. multifidus CSA between the right and left sides decreased between the initial and final evaluations. Conclusions: Hypertrophy of multifidus occurred over a 3 month period during which dynamic mobilisation exercises were the only exercise performed. Potential relevance: Dynamic mobilisation exercises maybe a useful rehabilitative technique for horses in which m. multifidus has atrophied in response to back pain.     

多杆式零速度钵苗移栽机植苗机构运动学模型与参数分析

为了分析多杆式零速度钵苗移栽机植苗机构的作业性能,建立了该机构的位移、速度和加速度方程,用Visual Basic 6.0语言编写了该机构的辅助分析和仿真程序。利用该程序分析了几个主要参数对该机构运动特性的影响：曲柄摇杆机构中的曲柄长度对栽植嘴的轨迹和形成的穴口大小影响都很大,而且对移栽后动轨迹的垂直度影响也很大;连杆长度影响栽植嘴的轨迹高度,对形成的穴口的大小和移栽后动轨迹的垂直度影响不大;摇杆长度和连杆的夹角对栽植嘴的轨迹形状和形成的穴口大小影响都不大,但都对移栽后动轨迹的垂直度有影响。根据参数影响分析结果,利用该程序找到一组较优机构参数,其对应的轨迹和姿态能满足蔬菜移栽农艺的要求,且植苗时水平速度为0.03?m/s,实现零速度移栽。     

三维前方交会法测量树高及其精度分析

为了解决森林调查中因地形起伏不能通过皮尺或者视距法获得测站与目标树的水平距离,而导致不能通过一般三角测量的办法来测量树高的问题,该文将测量高程的前方交会法应用到测树上来获得树高数据.前方交会法的内容为两台仪器与目标树构成一个三角形,测量两台仪器中心的斜距和三个夹角,利用正弦定理推算目标树与一台仪器的水平距离,然后再测得树顶和树根两处的天顶距,利用三角测量获得树高.经纬仪和罗盘仪是森林调查中常用的工具,通过对该模型的精度分析和实验发现经纬仪采用此方法可以控制误差在5%以内,满足林业上的测量要求,而罗盘仪采用此方法误差范围超过5%,不能满足要求.此方法可以配合经纬仪进行树高测量.