Homology modelling of annexin I: implicit solvation improves side-chain prediction and combination of evaluation criteria allows recognition of different types of conformational error

Annexin I homology models were built from the annexin V crystalstructure. Three methods for side-chain prediction were testedbased on molecular mechanics conformational search, the useof a rotamer database, or a combination of these two methods.We showed that rotamer-based methods were more efficient andthat molecular mechanics energy minimizations, prior to rotamerselection, did not afford clearly improved predictions. Modelsbuilt in vacuo and with an implicit solvation term were comparedwith the annexin I crystal structure which became availableduring the course of this study. The analysis of solvation energies,root mean square deviations, Xi angles and hydrogen bonds showedthat models built with implicit solvation were of better quality.In annexin V, repeat III displays A-B and D-E loop conformationsquite different from other repeats. Since the sequence differencessuggest that repeat III in annexin I might present a conformationsimilar to other repeats, two annexin I models with differentrepeat III conformations were built and compared to determinewhether the correct conformation could have been predicted.We show that using a combination of evaluation criteria, itis possible to discriminate unequivocally between the nativeand the incorrect fold, stressing that only one criterion shouldnot be used to evaluate protein structures.     

非数值化产品形位描述模型

传统的形状及位置表示模型通常是建立在低层次的无应用意义的几何拓扑元素之上，因而无法很好地支持计算机辅助设计（ＣＡＤ）向实用化和智能化方向发展。本文提出了一种非数值化的基于约束的产品形位描述模型，并对该模型中存在的一些问题进行了深入的讨论。该模型符合设计人员实际设计思维与过程，同时也支持高层次产品设计信息以及产品的设计过程信息，因而为传统ＣＡＤ系统向新一代实用化智能化ＣＡＤ系统过渡提供了一个良好的产品形位表示模型。     

Discrete quadratic curvature energies

We present a family of discrete isometric bending models (IBMs) for triangulated surfaces in 3-space. These models are derived from an axiomatic treatment of discrete Laplace operators, using these operators to obtain linear models for discrete mean curvature from which bending energies are assembled. Under the assumption of isometric surface deformations we show that these energies are quadratic in surface positions. The corresponding linear energy gradients and constant energy Hessians constitute an efficient model for computing bending forces and their derivatives, enabling fast time-integration of cloth dynamics with a two- to three-fold net speedup over existing nonlinear methods, and near-interactive rates for Willmore smoothing of large meshes.     

On methods of defuzzification of parametrically represented fuzzy numbers

A comparative analysis of such methods of defuzzification of fuzzy numbers as WABL (Weighted Averaging Based on Levels), centroid, and mean of maxima (MOM) is presented in the study. Analytic formulas are presented for calculating the defuzzification values for parametrically represented fuzzy numbers of triangular and trapezoidal form.     

下扬子北缘前陆盆地构造变形样式

下扬子北缘前陆盆地经历了印支、燕山、喜山等多期构造改造,构造环境经开裂扩张—碰撞拼合—拉伸断陷等多次转换,最终形成了上部拉伸、中部逆冲推覆、下部拆离滑脱的"三层楼阁"式分层构造变形组合的构造几何学模式.其构造变形主要受中三叠世扬子地块与华北地块的陆—陆碰撞造山作用控制,具有横向上强弱分带、垂向上形变分层的特征.可划分为伸展变形、冲断褶皱变形、拆离滑脱变形等3种构造变形样式.      

用偏微分方程构造过渡面

用偏微分方程的构造曲面是一种新兴的方法，本文借若干算例说明如何用偏微分方程构造两已知曲面之间的过渡面。论文着重讨论用四阶方程构造一阶连续的过渡面。     

橡胶挤出机平均温差分析与计算

从理论上推导挤出机平均温差的计算公式，并指出与一般换热器平均温差计算的异同。     

高精度合成地震记录制作技术研究

制作高精度的合成地震记录是精细储层描述的基础，本文在分析合成地震记录原理的基础上，从地震剖面的极性判断、平均速度的选取，反射系数的准确提取，子波的精确估算等方面对制作合成记录的要点进行了分析，通过提高以上四方面的精度，提高了制作合成地震记录的精度，并提出了一套可行的合成地震记录的检查方法。     

加权算术平均与几何平均关系式的新证法

利用函数极小点的性质,得到了若干个正数的加权算术平均与几何平均关系式的新证法     

关于移动平均过程两系数的推导

对经济预测方法中两公式给出了证明，两公式的系数被显式推导出来，这两个公式是时间序列模型公式，广泛用于经济预测之中，但文献上很难找到推导过程，本文的证明是基本的，无需高深数学知识即可理解．