Krylov子空间投影法研究进展

Ｋｒｙｌｏｖ子空间投影法是一类非常有效的大型稀疏线性代数方程组解法，已被广泛应用于各种领域，随着左右空间Ｌｍ，Ｋｍ的不同取法可以得到许多人们熟知的方法．本文按矩阵Ｈｍ的不同类型，即为上Ｈｅｓｓｅｎｂｅｒｙ阵还是三对角阵将Ｋｒｙｌｏｖ子空间投影法分成两大类，从每步迭代是否具有最优性和方法的存储量、计算量等方面对Ｋｒｙｌｏｖ子空间法及其最新进展进行评述，指出Ｋｒｙｌｏｖ子空间法的局限及今后的研究方向．     

利用积分算子方程的小波－矩量法分析频率选择反射面

小波－矩量法以小波基作为矩量法中的基函数，通过Ｇａｌｅｒｋｉｎ法可以获得很稀疏的阻抗矩阵，用迭代法求解时可减少计算机内存和计算时间。该文以有限尺寸的频率选择反射面为例，用小波－矩量法分析散射特性和电流分布，着重讨论了阻抗矩阵的稀疏化程度对计算精度的影响。结果表明，当非零元素仅为１０％时，仍能达到满意的精度，因此小波－矩量法不失为分析电大尺寸问题的一种有效方法     

《光电技术》课程的教学改革与实践

对《光电技术》课程的教学内容和教学方法进行了改革，并提出了如将教学和科研有机结合起来开展实验教学改革，使教学能紧跟上高科技的飞速发展，充满活力和时代气息。实践证明，这些教学改革效果良好，不仅有助于激发学生学习兴趣，而且有利于培养学生分析问题和解决问题的能力。     

Samples Selection for Artificial Neural Network Training in Preliminary Structural Design

An artificial neural network (ANN) is applied in the preliminary structural design of reticulated shells. Major efforts are made to enhance the generalization ability of networks through well-selected training samples. Number-theoretic methods (NTMs) are adopted to generate samples with low discrepancy, i.e.uniformly scattered in the domain, where discrepancy is a quantitative measurement of the uniformity. The discrepancy of the NTM-based sample set is 1/6-1/7 that of samples with equal spacing. In a case study,networks trained by NTM-based samples are compared with those trained by equal-spaced samples in generalizing performance. The results show that both the computational precision and stability of the former ANNs are more satisfactory than those of the latter. It is concluded that the flexibility of ANNs in generalizing can be effectively increased by use of uniformly distributed training samples rather than simply piling data.More reliable uniformity should be obtained, however, through NTMs instead of equal-spaced samples.     

W_(18)Cr_4V钢真空油淬白亮层、熔化层形成原因的试验研究

W_(18)Cr_4V钢真空加热油淬后,表面出现白亮层和熔化层等异常现象。本文利用金相显微镜,显微硬度计、扫描电子显微镜和电子探针等手段对白亮层和熔化层进行了分析研究。试验表明,白亮层、熔化层均是真空油淬增碳的结果。本文对白亮层、溶化层形成原因进行了比较深入的分析探讨提出了产生白亮层必须同时具备的三个条件。     

油溶性银漂染料的合成及性能研究

合成并鉴定了黄色、品红色及青色共１１个油溶性偶氮染料，研究了染普在溶剂中的光谱性质和油溶性，结果表明，各染料色光纯正、有害吸收少，分子支链度大的染料Ｙ－２、Ｙ－６等具有良好的油溶性，可望用于银漂感光材料。     

Forecasting recessions using the yield curve

We compare forecasts of recessions using four different specifications of the probit model: a time invariant conditionally independent version; a business cycle specific conditionally independent model; a time invariant probit with autocorrelated errors; and a business cycle specific probit with autocorrelated errors. The more sophisticated versions of the model take into account some of the potential underlying causes of the documented predictive instability of the yield curve. We find strong evidence in favour of the more sophisticated specification, which allows for multiple breakpoints across business cycles and autocorrelation. We also develop a new approach to the construction of real time forecasting of recession probabilities. Copyright © 2005 John Wiley & Sons, Ltd.     

复变函数论教学内容与教学方法的新探

随着高中数学教材内容的不断更新,高师院校复变函数论课程内容和教学方法的调整势在必行。本文在分析现状的前提下,就复变函数论课程内容和教学方法进行了一些有益的探索。     

新型红外测油仪中的液芯波导技术

首次将液芯波导技术应用于中红外吸收测量的油成分分析领域, 研制的新型MFA-450型红外测油仪的灵敏度比现有同类型仪器提高一个数量级, 检出限为0.01 mg/L(油/萃取剂).     

物理精炼菜籽油的前处理——菜籽油的物理精炼研究(Ⅱ)

本课题采用正交试验方法,对脱胶添加剂和国产脱色白土的种类、用量及其他操作条件进行筛选试验研究,将试验结果对贵州产二级毛菜籽油进行前处理,经水蒸汽精炼后可以制得合符标准的外销色拉油。