Efficient Legendre moment computation for grey level images

Legendre orthogonal moments have been widely used in the field of image analysis. Because their computation by a direct method is very time expensive, recent efforts have been devoted to the reduction of computational complexity. Nevertheless, the existing algorithms are mainly focused on binary images. We propose here a new fast method for computing the Legendre moments, which is not only suitable for binary images but also for grey level images. We first establish a recurrence formula of one-dimensional (1D) Legendre moments by using the recursive property of Legendre polynomials. As a result, the 1D Legendre moments of order p, L_p=L_p(0), can be expressed as a linear combination of L_p-1(1) and L_p-2(0). Based on this relationship, the 1D Legendre moments L_p(0) can thus be obtained from the arrays of L₁(a) and L₀(a), where a is an integer number less than p. To further decrease the computation complexity, an algorithm, in which no multiplication is required, is used to compute these quantities. The method is then extended to the calculation of the two-dimensional Legendre moments L_pq. We show that the proposed method is more efficient than the direct method.     

冗余磁盘阵列的故障容错分析

本文在介绍冗余磁盘阵列(RAID)的故障容错机理之后,着重研究了设备故障对RAID系统可靠性的影响.其平均持续正常工作时间和系统在线修复设备故障容许的平均间隔时间的计算结果表明,只要在一定的容许时间内替换或修复故障磁盘,系统可保持持续正常工作状态.     

化学镀Ni—P镀层的X射线衍射研究

根据X射线衍射分析结果,对化学镀高P(含P>11wt％或19at％)Ni-P镀层加热时效时,镀层成分和加热温度对结构转变的影响作了研究,结果表明,高P共晶、过共晶(含P>11wt％或19at％)合金的结构转变有如下特征:(1)相同加热时效条件下,Ni-P合金的结构转变与成分有密切关系:(2)对同一成分的过共晶合金,Ni-P合金的结构转变与时效温度密切相关;(3)过共晶合金在290～360℃温度范围内时效处理,出现Ni_xP_y介稳相,X射线衍射分析认为Ni_xP_y为Ni_(12)P_5。     

SnO催化合成环烷酸乙二醇酯增塑剂的研究

介绍了用SnO非酸性催化剂催化合成环烷酸乙二醇酯增塑剂(NAEP)的方法。讨论了反应温度、醇酸摩尔比、催化剂用量和反应时间等因素对酯化反应的影响,给出了适宜的工艺条件。 NAEP应用于PVC电缆料及丁腈橡胶配方中取得了良好的效果。与邻苯二甲酸酯增塑剂相比,具有更好的经济价值。     

3^n阶矩阵乘法的分块算法

针对３＾ｎ阶矩阵的乘法运行，给出了一种分块算法，其乘法运行量比常规的矩阵乘法计算方法和补零的基－２算法都有所减少。     

AlGaAs／GaAs HBT表面效应的二维数值分析

采用表面效应集总模型综合考虑表面费米能级钉扎和表面复合效应，对ＡｌＧａＡｓ／ＧａＡｓＨＢＴ表面效应的影响进行了二维数值模拟。结果表明，表面态的存在对集电极电流几乎不产生影响，但显著增加基极电流，使得电流增益明显下降。同时还发现在台面结构ＡＩＧａＡｓ／ＧａＡｓＨＢＴ中外基区表面复合的集边效应，即外基区表面复合主要发生在发射极台面与外基区的交界处附近，与外基区长度基本无关。模拟还表明基区缓变结构可以减少表面复合，提高电流增益。     

FAST MEASUREMENT OF ASH CONTENT IN COAL WASHING PLANT

The coal filter cake is a product of fine coal after floatation which has an ash content of 7-13%, water content of 30±2%, and a particle size of less than 1 mm. The ash content was measured by the intensity of the single backscattered gamma-ray, and its accuracy is mainly dependent on the energy of the gamma-ray. The 238Pu low energy photon source is selected in this work. The energy of its gamma-ray is 15 keV, which can result not only in the best sensitivity, but also in the lowest contribution to the environment radiation. The root mean square deviation of the ash measurement is±0.33% (±1σ).     

几种火焰喷焊自熔性合金层的耐磨性能

研究了不同自熔性合金粉末火焰喷焊层的显微组织与抗磨粒磨损性能，并对其磨面形貌进行了ＳＥＭ观察分析。结果表明，在Ｎｉ６０自熔性合金中加入适量的镍包ＷＣ粉末可明显提高其喷焊层的抗磨粒磨损性能。当ＷＣ的加入量为３５％（ｗｔ）左右时，该喷焊层与６０Ｓｉ２Ｍｎ调质钢相比，相对的耐磨性可提高６倍以上。     

MOS结构准静态测试中的异常C—V曲线

本文报导了MOS结构在准静态测试中的异常电容-电压曲线。讨论了它们产生的原因。