基于Pro/E的曲柄摇杆机构运动仿真

利用Pro/E建立了曲柄摇杆机构的3D模型,并对该模型进行了动态仿真,仿真结果实现了对机构运动的可视化研究。最后得出了分析点的速度、加速度、角位移等随时间变化的曲线。仿真结果表明:在不同的速度模式下,分析点的速度、加速度、角位移随时间而变化,运动过程中分析点存在着抖动现象。仿真结果实现了对机构的全面可靠的动态分析,大大提高了机构的分析效率,对于优化机构设计有重要的指导意义。     

矩形线框进入匀强磁场时运动情况分析

掌握矩形线框进入匀强磁场时的运动情况可进一步理解法拉第电磁感应定律。用解微分方程并结合牛顿运动定律得出其运动的位移、速度和加速度与时间的关系为e-kt函数关系,得出线框在匀强磁场中可以做匀速运动、减速运动或加速运动,弄清其运动曲线关系的实质。     

Design of fuzzy adaptive washout algorithm based on the novel tilt coordinate

Motion simulator usually appears the phenomenon of false cues and the workspace is limited in the process of washout. The proposed washout algorithm combines fuzzy logic control with the vestibular system to design the tilt coordination fuzzy adaptive filter, in order to minimize the vestibular sensory error below the human perception threshold. Owing to tilt coordination angular velocity limiter, the loss of low-pass acceleration must be compensated by the acceleration transform model. The translational channel decreases the possibility of the workspace beyond limitation and expands the scope of motion platform simulating input acceleration by using third-order filter. The simulation results show that the proposed algorithm can effectively overcome the phase retardation of classical washout algorithm, and then prevent the produce of false cues, decrease the displacement of motion platform simultaneously; in addition, white Gaussian noise simulates large variations in acceleration. The proposed washout algorithm can have maximal extreme value of acceleration and accurate simulating performance in general. It also proves that the proposed washout algorithm has a strong adaptability and reliability, which can effectively improve the dynamic fidelity for motion simulator.     

加速度瞬心问题的讨论

利用加速度瞬心的概念，推导了加速度瞬心相对静系、动系的坐标公式及任一点相对加速度瞬心的加速度表达式。     

Numerical simulation on floating behavior of buoyancy tank foundation of anemometer tower

The intact stability and damage stability of a model of an anemometer tower with buoyancy tank foundation are computed by the finite element software MOSES in this paper. The natural period of the anemometer tower is discussed through frequency domain analysis. The influence of a single factor, such as towing point position, wave height, wave direction and wave period, on towing stability is discussed through time domain analysis. At the same time, the towing stability under the condition of various combinations of many factors is analyzed based on the meas- ured data of the target area. Computer simulation results show that the intact stability is preferable and the damage stability is sufficient under the condition of plenty of subdivisions. Within the scope of the buoyancy tank foundation, the higher the towing point position is, the better the stability is. Wave height has a great impact on the motion amplitude of buoyancy tank foundation, but the effect on the acceleration is not obvious; wave period has a great impact on the acceleration, while the effect on the motion amplitude is not obvious; following-waves towing is more conducive to safety than atry.     

浅析标枪助跑速度与成绩的关系

提高标枪助跑的可控速度是获得理想初速度的关键.良好的加速形式是助跑速度逐渐增大的过程.标枪出手的可控速度应处在助跑速度的最大速度峰值,所以.在标枪运动员的训练过程中,应从提高助跑加速的形式曲线即可控速度方面进行训练,减少助跑速度的损失,这对掷标枪运动成绩有着重要的现实意义.统计分析可为进一步改进技术,指导训练,提供参考依据.     

建筑结构地震响应混沌特性及影响因素分析

采用混沌时间序列分析方法分别对以经典混沌信号和地震动为激励的结构响应进行混沌特性分析,从关联维数、Kolmogorov熵及最大Lyapunov指数等定量指标的角度,考察结构自振周期、地震动的类型和幅值等因素对结构地震响应的非线性特性的影响。研究结果表明:在经典混沌信号和地震动作用下,经过结构的放大和滤波作用,结构加速度响应仍然保留了混沌特性,且通过混沌参数的变化程度能够判断结构是否进入弹塑性状态。结构自振周期为结构加速度响应的混沌特性的主要影响因素;幅值对经典混沌信号作用结构下加速度响应的混沌特性影响较为显著;而地震动的类型、幅值等因素对地震动作用下响应的混沌特性影响更为显著。     

溜溜球的力学原理及运动过程分析

本文阐述了溜溜球的力学原理，并对其运动过程进行了系统的理论分析，从中得出其平均动力为匀变速垂直运动，转动是均变速运动。若考虑到转向时平动动能的损失及空气阻尼和细胞麻擦阻力的作用损失的机械能，实际操作中需要及时给予补充。     

情景模拟法在高校微积分教学中的应用——以模拟运动过程为例

本文针对高校微积分教学的对象主要为高校低年级学生的特点,探讨情景模拟法在高校微积分教学中的应用。本文重点选取物理中的运动过程作为基本情景对微积分的基本概念进行分析,分别选取匀速直线运动、匀加速直线运动和变加速直线运动等,通过从微积分角度对它们重新分析,很自然地得出微积分理论中的定积分、不定积分、二重积分等几个问题的基本原理,以此表明情景模拟法在微积分教学中的有效性。     

Influence of interactive videodisc instruction using simultaneous-time analysis on kinematics graphing skills of high school physics students

Real-time kinematical analysis of physical phenomenon is the graphing of displacement, velocity, and acceleration versus time data simultaneously with the motion of the object. Brasell (1987) found that students using real-time analysis with microcomputer-based laboratory tools significantly improved their kinematics graphing skills as compared to students using delayed-time graphing (kinematics graphs produced after the motion of the object). However, using computer reanimation of videotaped images, Beichner (1990) found no difference in student learning between the simultaneous-time (kinematics graphs produced simultaneously with the motion of the image of the object, such as a video-recorded image or a computer reanimated image) and the delayed-time treatments. This investigation considers student analysis of videodisc-recorded images, with treatments over an extended time. Using quantitative, qualitative, and retention data, we found no significant learning difference between using simultaneous-time and delayed-time analysis for student understanding of kinematics graphs. However, the results imply that simultaneous-time analysis may have advantages in some areas.     

曲线运动加速度公式的推导和讨论

利用加速度的定义和曲率圆的概念较简单地推导出了一些曲线运动中加速度的公式,并得出一些重要结论。     

速度瞬心轨迹与运动初瞬时加速度瞬心

从刚体平面运动的速度瞬心轨迹出发,推导得到在刚体由静止开始运动的初瞬时加速度瞬心与速度瞬心重合,可用于解答运动初瞬时刚体平面运动的动力学问题。     

浅析工程图学的教学改革

通过对大学工科工程图学教学现状的分析,提出工程图学教学调整的具体内容、改革的具体方法和取得成功的经验。     

匀加速直线运动加速度测定实验设计

利用气垫导轨及电脑通用计数器测定匀加速直线运动的加速度 .测定误差为- 0 67%     

用数码技术研究抛射体的运动规律

利用数码相机拍摄小球运动的短片,利用Premiere,Photoshop和Excel等计算机软件合成轨迹图、处理数据和拟合运动曲线,从而探索抛射体的运动规律,并求得重力加速度值。最后分析了表差法处理结果的不确定度。     

Students' mathematical modeling of motion

We present results of an investigation of university students' development of mathematical models of motion in a physical science course for preservice teachers and graduate students in science and mathematics education. Although some students were familiar with the standard concepts of position, velocity, and acceleration from physics classes, most students had difficulty using these concepts to characterize actual or hypothetical motions. Furthermore, some students developed their own nonstandard method of describing accelerated motion in terms of changes in the average velocity, from the start of the motion up to a given time. This is in contrast to the physics community's use of the acceleration construct, defined in terms of changes in the instantaneous velocity, to describe such motion. Although the change in average velocity is not typically identified as an important construct in traditional physics texts, some students found it intuitively appealing, and were able to use it successfully to describe and predict motion. We conclude that by focusing on standard constructs, and ignoring possible intuitive ways that students might view motion, standard kinematics instruction may miss an opportunity to maximize student understanding. © 2007 Wiley Periodicals, Inc. J. Res. Sci. Teach 45: 153–173, 2008.     

Motion classification of EMG signals based on wavelet packet transform and LS-SVMs ensemble

This paper presents an effective method for motion classification using the surface electromyographic (sEMG) signal collected from the forearm. Given the nonlinear and time-varying nature of EMG signal, the wavelet packet transform (WPT) is introduced to extract time-frequency joint information. Then the multi-class classifier based on the least squares support vector machine (LS-SVM) is constructed and verified in the various motion classification tasks. The results of contrastive experiments show that different motions can be identified with high accuracy by the presented method. Furthermore, compared with other classifiers with different features, the performance indicates the potential of the SVM techniques combined with WPT in motion classification.     

悬点振动单摆运动的计算机模拟

根据角速度和角加速度的定义,给出了处理非线性微分方程的基本算法,用计算机形象直观地模拟了悬点振动单摆的运动．     

阻尼器连接的毗邻建筑地震响应分析(英文)

建立阻尼器连接的毗邻建筑在地震力作用下的运动方程．在求解地震响应时,地面运动加速度被描述为一随机过程．由于结构系统的非正交阻尼性质,用虚拟激励法在频域内求解结构地震响应．通过分析得出,毗邻建筑用阻尼器连接后,结构的地震响应得到有效控制,较连接前明显改善;选择一定的阻尼器参数可得最佳的减震效果．     

悬点振动单摆运动的计算机模拟

根据角速度和角加速度的定义,给出了处理非线性微分方程的基本算法,用计算机形象直观地模拟了悬点振动单摆的运动。