一种OpenGL局部缩放算法及应用

缩放是OpenGL三维模型展示的基本操作之一,一般缩放时由于整个场景围绕视景体中心缩放,感兴趣区域在视图窗口中的位置会不断变化甚至离开视景体,需要不断地执行平移操作,不断地修正感兴趣区域在视图窗口中的位置,无法集中精力观察工程计算中模型的变化细节。为了解决该问题,从图形学角度提出了一种改进的局部缩放算法,实现了用鼠标滚轮缩放模型时,鼠标选择处的模型不离开视景体而相对视图窗口的位置保持不变,省去了传统算法中用户进行缩放操作时需要不断进行平移的操作．改进了用户体验。该算法在多个可视化项目中得到实际应用．取得了很好的操作体验。     

不规则直流线圈磁场的计算方法研究

将不规则直流线圈等效为若干段载流直导线的组合,通过坐标变换和磁场变换计算出单根载流直导线的磁场,进而叠加求和得到整个不规则直流线圈的磁场.计算示例表明,该方法计算不规则直流线圈的磁场简单易行,可用于实际工程中线圈磁场的计算.     

离轴式拖车移动机器人的任意路径跟踪控制

离轴式拖车移动机器人属于非完整系统,当车头线速度随时间变化且过零变号时,难以用一个控制器实现系统对期望路径的跟踪.本文研究离轴式拖车移动机器人系统的任意路径跟踪问题.首先由系统和虚拟小车的运动学方程得到误差状态模型,线性化后用坐标变换将其化为标准型,然后基于Lyapunov方法构造出一种跟踪控制律.只要车头的运动线速度有界且不趋于零,其导数有界,则所设计的控制律就可以保证系统跟踪任意的期望路径,且跟踪误差最终一致有界,最终界的大小与期望路径的曲率变化率成比例.当期望路径的曲率变化率为零或趋于零时,所设计的控制律可以保证拖车移动机器人指数收敛到期望路径.仿真结果证实了控制律的有效性.     

Comprehensive two-dimensional river ice model based on boundary-fitted coordinate transformation method简

River ice is a natural phenomenon in cold regions, influenced by meteorology, geomorphology, and hydraulic conditions. River ice processes involve complex interactions between hydrodynamic, mechanical, and thermal processes, and they are also influenced by weather and hydrologic conditions. Because natural rivers are serpentine, with bends, narrows, and straight reaches, the commonly-used one-dimensional river ice models and two-dimensional models based on the rectangular Cartesian coordinates are incapable of simulating the physical phenomena accurately. In order to accurately simulate the complicated river geometry and overcome the difficulties of numerical simulation resulting from both complex boundaries and differences between length and width scales, a two-dimensional river ice numerical model based on a boundary-fitted coordinate transformation method was developed. The presented model considers the influence of the frazil ice accumulation under ice cover and the shape of the leading edge of ice cover during the freezing process. The model is capable of determining the velocity field, the distribution of water temperature, the concentration distribution of frazil ice, the transport of floating ice, the progression, stability, and thawing of ice cover, and the transport, accumulation, and erosion of ice under ice cover. A MacCormack scheme was used to solve the equations numerically. The model was validated with field observations from the Hequ Reach of the Yellow River. Comparison of simulation results with field data indicates that the model is capable of simulating the river ice process with high accuracy.     

基于弹目GPS和弹体姿态的位标器框架角预置算法

给出了基于弹目GPS信息和弹体姿态信息的位标器框架角预置算法。该算法使用弹体飞行过程中的偏航角、俯仰角、横滚角、GPS信息以及目标的GPS信息,通过适当的坐标变换最终输出框架预置角。挂飞试验结果验证了该算法的有效性。     

不同坐标系之间的图形变换

本文对利用坐标变换公式及Ａｕｔｏ ＣＡＤ、ＭｉｃｒｏＳｔａｔｉｏｎ、ＭａｐＩｎｆｏ等不同的系统进行不同坐标系间的图形变换进行了分析，并指出了实际的作业步骤，这些方法为以后的因各种原因产生而需要进行的图形变换提供了有益的经验。     

洛仑兹变换式两种推导的比较与分析

对洛仑兹坐标变换式的两种推导方法进行比较，分析了各自的思路及特点。     

用坐标变换计算“一面两孔”的定位误差

用坐变换的方法对工件一面两孔定位时的定位误差进行了合理地分析计算，给出了定位误差对工序尺寸的函数关系式。     

洛仑兹变换式两种推导的比较与分析

对洛仑兹坐标变换式的两种推导方法进行比较，分析了各自的思路及特点。