三维数据获取及其预处理技术的发展趋势

对现有的三维数据获取及其预处理技术分别进行了总结和阐述。针对目前的发展现状,对数据获取与预处理技术的发展趋势进行了相应的展望。     

盱眙淮河明珠塔关键节点有限元分析

盱眙淮河明珠塔由于体型庞大,结构受力复杂,因此对结构关键部位的节点作进一步的分析是很有必要的。本文通过结合运用某分析前处理程序和某有限元分析软件,将实体细分模型插入整体模型,在最不利荷载组合情况下,对塔体底部受力最大的节点进行了有限元分析。     

Excel在数值模拟前处理中的应用

随着计算机技术的飞速发展,油藏数值模拟软件在油田中得到越来越广泛的应用。其前处理数据格式的准备工作花费了科研人员的大量时间。本文利用Excel对油田实际的生产数据编制了目前流行的几种数模软件(如:E clipse,CMG,V IP等)的前处理接口软件(SSF I)。通过实际应用表明该系统简化了数据准备的过程,并且简单易用。     

Separation of form from orientation in 3D measurements of aspheric surfaces with no datum

Measurement and characterisation of 3D form to maintain manufacturing quality has particular problems in cases such as lenses which do not generally have a clear measurement datum. A 3D-form measurement includes information about the form, the orientation and the position of the surface under test. Orientation and position can be design parameters or may result from misalignment of the test specimen on a measurement table. In either case, it is necessary to separate form from orientation and position if the data-set is to be fitted and compared with an “ideal” surface. In this paper two pre-processing algorithms are presented and examples given of the separation of form from orientation and position. The algorithm is applied to simulated data-sets consisting of up to 26,000 discrete points on a square grid, simulating the measurement of an aspheric lens in 3D. The rotationally symmetric data-set is translated for a distance x₀, y₀ and z₀ and rotated about two axes, x and y, to simulate misalignment. To simulate inaccuracies from a manufacturing process, normally distributed random noise is superimposed on the ideal surface. An application of pre-processing using a real data-set is also shown. Furthermore, form fitting is addressed and the interpretation of form by decomposition of the data into error types is discussed.     

多元红外导引头预处理电路带宽设计与仿真研究

以正交四元探测系统为例，介绍了多元红外导引头的工作原理。为了有效设计多元红外导引头预处理电路带宽，利用Matlab进行仿真，通过仿真分析了预处理电路高端和低端带宽的选择对信号提取的影响，并研究了预处理带宽选择对抗人工干扰的影响。仿真结果表明，频带低端设置对信号下沉有较大影响，频带高端设置对脉冲下降沿产生的负脉冲有较大影响。在对抗大倍数人工诱饵干扰时，电路的低端带宽选择会对抗干扰带来显著影响。最后利用仿真结果，设计了红外四元导引头的预处理电路，经内外场测试，该电路在目标脉冲信号提取及抗人工干扰性能方面表现出了良好的性能。     

一种改进的OMR技术在标准化考试中的应用

本文将一种改进的OMR技术用于标准化考试中,采用与普通光学标记阅读机完全不同的技术,使用光学字符识别的方法、算法完成答题卡上标记的识别。此系统中图像识别是识别出考生填写的表示选项的“勾、×、○、●、／、/”等各种手写符号,它属于脱机手写体汉字识别。本文提出的方法具有很高的识别率。     

一种改进的OMR技术在标准化考试中的应用

本文将一种改进的OMR技术用于标准化考试中,采用与普通光学标记阅读机完全不同的技术,使用光学字符识别的方法、算法完成答题卡上标记的识别。此系统中图像识别是识别出考生填写的表示选项的"√、╳、○、●、╲、╱"等各种手写符号,它属于脱机手写体汉字识别。本文提出的方法具有很高的识别率。     

基于粗糙几何的脱机手写体汉字预处理

传统的图像预处理方法未能预防汉字书写带来的伪特征点（断点、伪交叉点）,利用粗糙几何理论对汉字图像进行粗糙化,克服了以上缺点,同时减少图像大小,提高手写汉字识别速度。     

A new benchmark on the recognition of handwritten Bangla and Farsi numeral characters

The recognition of Indian and Arabic handwriting is drawing increasing attention in recent years. To test the promise of existing handwritten numeral recognition methods and provide new benchmarks for future research, this paper presents some results of handwritten Bangla and Farsi numeral recognition on binary and gray-scale images. For recognition on gray-scale images, we propose a process with proper image pre-processing and feature extraction. In experiments on three databases, ISI Bangla numerals, CENPARMI Farsi numerals, and IFHCDB Farsi numerals, we have achieved very high accuracies using various recognition methods. The highest test accuracies on the three databases are 99.40%, 99.16%, and 99.73%, respectively. We justified the benefit of recognition on gray-scale images against binary images, compared some implementation choices of gradient direction feature extraction, some advanced normalization and classification methods.     

金属板料成形CAE系统的前后置处理中几个关键技术的处理

力学模型离散化的方法、板料有限元节点编号的优化以及计算结果的可视化分等是金属板料冲压成形CAE系统前置处理和后置处理的一些关键技术问题,介绍并给出了处理方法,并在自行开发的金属板料冲压成形CAE系统SheetForm中得到应用验证。