Effects of mastication on the distribution of molecular weights and on the mechanical properties of native and commercial dental gutta percha (trans-polyisoprene)

Mastication of gutta percha (trans-polyisoprene) resulted in the selective scission of molecules, producing a narrower distribution of lower molecular weights. The mechanical properties of the samples also underwent a significant change due to mastication. The greater the content of incompatible substances (salts and oxides) in commercial gutta percha. the more substantial were these effects. The atmosphere (air, N₂, O₂) in which the experiments were conducted yielded significantly different results. The decrease in molecular weight was far greater in an O₂ atmosphere than under a current of nitrogen or air, owing to the combination of double bonds with O₂.     

MAXIMUM ENTROPY DECONVOLUTION OF XPS PEAK

Necessity of XPS spectrum,deconvolution,disadvantages of the traditional Fast Fourier Tranderm decon-volution method(FFT),princtple,method and advantage ofMaximum Entropy Deconvolution Method (MEM) are de-scribed.Criteria for determing the number of data points sam-pled in MEM are the main point disccussed in the paper,someXPS deconvolution applications of our MEM software showthat the MEM makes XPS deconvolution much easier than thetraditional FFT method.     

基于熵权的料场方案模糊多属性优选研究

砂石料场方案选择中存在着许多难以精确度量的模糊性因素，常规的平衡法、系统分析法很难对此进行有效的处理。将模糊数学理论应用于砂石料场的方案选择，提出了熵权与模糊理论相结合的砂石料场方案优选方法，重点对标准化属性矩阵的产生、主客观权重结合得到综合权重及相对接近度的计算等几个方面进行了说明，并通过实例验证了该方法的可行性与实用性。     

准连续波体制雷达最大熵方法的算法选择

准连续体制作为一种新型雷达体制以其固有的优越性给雷达界带来了巨大的冲击。其数字信号处理系统的开发是进一步完善该体制雷达的关键。本文针对数字信号处理系统中最大熵谱外推电路的算法选择进行了研究。     

变权组合预测模型在大坝安全监测中的应用

简要介绍了组合预测模型的基本原理，该模型改进了单一模型考虑因素的片面性，但常规的组合预测模型的权系数是固定的。考虑到各种模型的预测精度的变化，以及大坝安全监测数据存在的突变、时效等因素，固定权系数的组合预测模型有待进一步改进。文中提出了变权系数组合预测模型，并将其用于实际的大坝安全监测工程。结果表明，变权组合预测模型的预报精度高于其他模型。是一种值得推广的方法。     

Design optimization of 3D steel structures: Genetic algorithms vs. classical techniques

In this paper an elitist genetic algorithm (GA) developed by the authors is compared with common commercial solutions for complex structural optimization. After its prior validation on two-dimensional (2D) structures, the GA was tuned and improved in order to obtain structural elements with minimum weights that satisfy the ultimate limit states of the applicable building code. Subsequently, the same spatial structures were optimized using a commercial structural analysis program. Finally, the cost and weight improvements obtained using the GA, although at a higher computational cost, are discussed.     

幕帘涂布工艺

本文主要介绍涂布与塞孔工艺,并对此工艺进行特征描述与释疑。     

压缩奇偶相干态的熵压缩特性

用数值方法讨论了相干态强度、相位角和压缩参数对压缩奇偶相干态位置熵和动量熵压缩特性的影响。结果表明，压缩奇偶相干态的位置熵和动量熵均可呈现压缩性，压缩偶相干态的最大熵压缩度比压缩奇相干态的要大。熵压缩度与相干态强度、相位角和压缩参数均有关系，但压缩因子对场熵压缩的影响最大。当其它条件一定时，压缩偶相干态在压缩参数|β|=O．95时，位置熵(或动量熵)的压缩度最大，但压缩奇相干态无此特点。     

凝胶过滤色谱测定高分子量聚乙烯醇分子量和分子量分布

用凝胶过滤色谱对高分子量聚乙烯醇分子量、分子量分布进行剖析。采用Plaquagel-OH色谱柱,0.25mol/LNaNO3,0.01mol/L Na2HPO4-NaH2PO,pH=7的缓冲溶液流动相,流速1ml/min,示差折光检测器,柱温30℃,聚环氧乙烷作标准物。该方法能显著缩短分析时间,提高准确性,可用于对高聚合度聚乙烯醇进行研究和指导生产。     

基础锚栓预埋加固方案

结合工程实例 ,介绍轻钢结构系统基础锚栓预埋、加固解决方案 ,并介绍了加固系统的制作及使用方法 ,可供工程人员参考