高稳定度大视场大气风场测量新方法

提出了一种利用广角迈克耳孙干涉仪在动镜固定的情况下,依靠视场角的变化以调制光程差来测量大气风场的新方法以及探测模式和装置设想;采用干涉成像光谱技术对被探测源谱线为高斯轮廓时风扬的速度、温度的测量进行了分析和计算,这种方法具有稳定度高、实时性好,精确度高、大视场和高通量等优点。     

N-酰基壳聚糖的制备及取代度控制的研究

对壳聚糖于醋酸／甲醇介质中的N-乙酰、N-丙酰、N-丁酰、N-己酰化反应进行了研究．结果表明：壳聚糖的N-酰基化反应在室温1h内接近完全,N-酰基取代度(Ds)取决于醋酸和甲醇浓度以及酸酐与氨基的摩尔比(R),对醋酸和甲醇浓度及酸酐与氨基摩尔比进行控制,可制得不同取代度的N-酰基壳聚糖,较为合适的反应条件为：MeOH浓度80％(w／w)、AcOH浓度1％(w／w)、酸酐与氨基摩尔比O～3．     

两类新的广义Ball曲线

本文提出两类新的广义Ｂａｌｌ曲线,一类介于Ｗａｎｇ（王国瑾）和Ｓａｉｄ广义Ｂａｌｌ曲线之间,另一类介于Ｂｅｚｉｅｒ和Ｓａｉｄ曲线之间,同时给出有关的升阶公式、递推算法及转化成Ｂｅｚｉｅｒ形式的系数公式。     

Modeling microgeometric structures of porous media with a predominant axis for predicting diffusive flow in capillaries

This paper presents a method for modeling microgeometric structures of porous media with a predominant using successive cross-sections. The proposed model takes into account the properties of diffusive flow in capillaries. In order to characterize uncertainty and imprecision occurring in geometric features of cross-sections, we introduce the concept of connection degrees as well as tracking degrees based on fuzzy theory. The proposed model can be used for classifying different types of media and finding the relationship between the geometric structure of a porous medium and its physical properties. This model has been successfully applied to polyester yarn structure.     

弛豫铁电体介电可调性的研究

无铅弛豫铁电体具有较好的介电可调性,在顺电相有较大的介电常数和极小的损耗,因较大的优值而被广泛地用于微波器件.根据现有的介电可调性理论,通过参量的适当修正,对介电可调性的表达式做了合理的探讨,结论适用于处理实验结果.比较发现,在电场作用下顺电相保持不变的近似得出的结论与实验结果差距较大,而转化为铁电相与实验结果完全吻合.考虑外加电场和自发极化对弹性吉布斯自由能的修正,导出了高电场对介电常数的修正关系,与实验结果相符.提出了介电可调度的概念与计算公式,能够定量表示掺杂对介电可调性的影响.     

Adaptive Free-Knot Splines

This article proposes a function estimation procedure using free-knot splines as well as an associated algorithm for implementation in nonparametric regression. In contrast to conventional splines with knots confined to distinct design points, the splines allow selection of knot numbers and replacement of knots at any location and repeated knots at the same location. This exibility leads to an adaptive spline estimator that adapts any function with inhomogeneous smoothness, including discontinuity, which substantially improves the representation power of splines. Due to uses of a large class of spline functions, knot selection becomes extremely important. The existing knot selection schemes—such as stepwise selection—suffer the difficulty of knot confounding and are unsuitable for our purpose. A new knot selection scheme is proposed using an evolutionary Monte Carlo algorithm and an adaptive model selection criterion. The evolutionary algorithm locates the optimal knots accurately, whereas the adaptive model selection strategy guards against the selection error in searching through a large candidate knot space. The performance of the procedure is examined and illustrated via simulations. The procedure provides a significant improvement in performance over the other competing adaptive methods proposed in the literature. Finally, usefulness of the procedure is illustrated by an application to actual dataset.     

函数变换缩小数据级比偏差效果的比较原则

针对缩小序列级比偏差的单调变换,研究了在函数的和变换与每一个变换缩小级比偏差效果优劣的比较原则基础上证明了两函数之正线性和变换缩小级比偏差效果介于这两个函数缩小级比偏差效果之间.因此如果两函数之正线性和变换不比任何一个单独变换效果差,其实质是两函数商的比值是常数,即两函数变换缩小级比偏差效果一样好,并通过实例验证了结论.     

First fall degree and Weil descent

Polynomial systems arising from a Weil descent have many applications in cryptography, including the HFE cryptosystem and the elliptic curve discrete logarithm problem over small characteristic fields. Understanding the exact complexity of solving these systems is essential for the applications. A first step in that direction is to study the first fall degree of the systems. In this paper, we establish a rigorous general bound on the first fall degree of polynomial systems arising from a Weil descent. We also provide experimental data to study the tightness of our bound in general and its plausible consequences on the complexity of polynomial systems arising from a Weil descent.     

三维结构和氧化度对C6位氧化再生纤维素止血材料性能影响

C6位氧化再生纤维素作为可吸收止血材料,其止血性能受材料理化性质的影响。通过比较氧化再生纤维素的吸水率、凝胶化速率、溶解速率、降解速率、抗老化性能和止血效果,研究三维结构和氧化度对氧化再生纤维素性能影响。结果发现,氧化度增高,氧化再生纤维素吸水率增强,凝胶化速率加快,溶解速率和降解速率变快,抗老化性能变差,产品有效期变短。纤丝松散网状多孔结构比纱布致密结构更有利于提高吸水率,加快凝胶化速率和溶解速率;同时降低氧化剂用量,提高抗老化性能。同一氧化度条件下,纤丝止血速率优于纱布,止血效果更好。     

TiO2烧结助剂对纳米η-Al2 O3制备Al2 O3-Cr2 O3固溶体的影响研究

以纳米η-Al₂O₃粉和工业铬绿为原料,以摩尔比1:1配比制备Al₂O₃-Cr₂O₃固溶体,以TiO₂为烧结助剂,在还原气氛下经1400 ℃、1500 ℃和1600 ℃固相烧结.研究了TiO₂的加入对纳米η-Al₂O₃制备Al₂O₃-Cr₂O₃固溶体的致密度、线收缩率、相组成、晶胞参数、互扩散程度和微观结构的影响.结果表明:TiO₂的加入能促进Al₂O₃-Cr₂O₃固溶体的致密化;当温度为1600 ℃,TiO₂的添加量为2wt;时,试样的体积密度最大为4.57 g·cm^-3,线收缩率为19.8;;TiO₂的加入能使Al₂O₃-Cr₂O₃固溶体中Al³⁺和Cr³⁺的互扩散程度增加;微观结构表明,TiO₂的加入能使Al₂O₃-Cr₂O₃固溶体晶粒之间结合更紧密,实验温度范围内,随着TiO₂添加量的增加晶粒从沿晶断裂向穿晶断裂转变,只在晶间和晶内存在极少量气孔,当温度为1600 ℃,TiO₂的添加量为2wt;时,晶粒大小较均匀,平均晶粒尺寸约10μm.