鱼眼镜头光学设计

鱼眼镜头的视场高达180°或超过180°,可以作为全景电影的摄影和放映镜头,本文介绍了它的结构型式的发展,讨论了它的成象理论,给出了适合它的理想象高公式和光栏球差公式,最后提供了一个实例。     

天坛皇穹宇声学现象的新发现

天坛是我国珍贵的文化遗产，也是世界上最大的祭天建筑群，其设计之精、建筑之巧、风格之奇、回音之妙，在世界古我上亦属罕见，成为人类建筑艺术的瑰宝，被列为我国四大回音古建筑之首。１９９４年３月２６日，作者在天坛皇穹宇内发现了一个回音壁和东、西配殿相关的奇妙声学现象－天坛”对话石“声学现象。     

准精度法解装配尺寸链

本文针对装配尺寸链反计算通常所采用方法的局限性,以公差与配合国家标准中有关标准公差的规定为依据,提出了新的解算方法.     

Geometric integration methods for general nonlinear dynamic equation based on Magnus and Fer expansions

Ithasbeenknownforalongtimethatthesolu tionofthefollowingdifferentialequation :U· =A(t)U ,　U(t0 ) =I ,(1)whereA (t)standsforasufficientlysmoothn×nmatrixorlinearoperator ,canlocallybewrittenintheform[1]U(t ,t0 ) =eΩ(t,t0 ) ,(2 )whereΩisobtainedasaninfiniteseriesΩ(t ,t0 ) =∑∞k =1Ωk(t,t0 ) . (3)Eqs .(2 )and (3)constitutetheso calledMagnusex pansionofthesolutionofthedifferentialequation(1) .EachtermΩkintheseries (3)isamultiplein tegralofcombinationsofnestedcommutators ,anditcanbeobtain…     

Approximation of NURBS Curves and Surfaces Using Adaptive Equidistant Parameterlzatlons

Non-uniform rational B-spline (NURBS) curves and surfaces are very important tools for modelling curves and surfaces. Several important details, such as the choice of the sample points, of the parameterization, and of the termination condition, are however not well described. These details have a great influence on the performance of the approximation algorithm, both in terms of quality as well as time and space usage. This paper described how to sample points, examining two standard parameterizations: equidistant and chordal. A new and local parameterization, namely an adaptive equidistant model, was proposed, which enhances the equidistant model, Localization can also be used to enhance the chordal parameterizatfon, For NURBS surfaces, one must choose which direction will be approximated first and must pay special attention to surfaces of degree 1 which have to be handled as a special case.     

亚式期权与欧式期权的实证比较

讨论了用欧式看涨期权和连续情形下的几何平均亚式期权中的看涨期权进行投资时收益和风险之间的关系。从上海和深圳证券交易所随机选取10只股票收盘价的数据进行实证分析,得出采用几何平均亚式期权进行投资比采用欧式期权进行投资风险更小,这与几何平均亚式期权的设计是相符的。     

基于颜色和形状的道路交通标志检测

提出了一种基于颜色分割和形状分析的交通标志检测方法.首先利用改进后的简单向量滤波器分割感兴趣色彩区域,对不同色彩区域进行相应形状检测.采用拐角特征与几何结构分析相结合的方法检测矩形与三角形标志,提出了一种基于对称性特征的简单编码算法,并应用于圆形检测.实验结果表明,该方法能在多种复杂场景中有效地定位交通标志,对天气变化有一定鲁棒性,为后继的交通标志识别工作奠定了良好基础.     

拟线性双曲方程的两种Blowup机制

对于一般的初值，拟线性双曲方程不一定存在整体经典解，若不存在整体经典解，则解在有限时间内blowup。主要考虑几种特殊的Burgers方程，讨论其经典解的存在区间以及解发生blowup时，几何blowup与常微blowup之间的先后顺序。     

转换桥的几何模型

针对两个系统之间的狭义转换桥在欧氏空间的实现问题，利用数学建模方法讨论了空间中左和右、上和下、内和外的转换问题，同时构造了转换桥理论中转换桥的两类三种几何模型．并讨论了单向桥的串与并几何模型和循环桥的串与并几何模型．     

Computational manufacturing

This paper presents a general framework for computational manufacturing. The methodology of computational manufacturing aims at integrating computational geometry, machining principle, sensor information fusion, optimization, computational intelligence and virtual prototyping to solve problems of the modeling, reasoning, control, planning and scheduling of manufacturing processes and systems. There are three typical problems in computational manufacturing, i.e., scheduling (time-domain), geometric reasoning (space-domain) and decision- making (interaction between time-domain and space-domain). Some theoretical fundamentals of computational manufacturing are also discussed.