配体二吡啶胺单氧化物的配位多样性

本文报道了以二吡啶胺单氧化物为配体的三个铜配合物的合成和X-射线衍射数据分析.在不同配位条件下,二吡啶胺单氧化物显示了配位多样性,配体酰胺上的氢原子发生转移或者消除,分子骨架在顺式和反式之间变换.此外,还发现了一个不同寻常的分子构型转换现象.     

Bayes Inference for Technological Substitution Data with Data-based Transformation

Bayesian inference via Gibbs sampling is studied for forecasting technological substitutions. The Box–Cox transformation is applied to the time series AR(1) data to enhance the linear model fit. We compute Bayes point and interval estimates for each of the parameters from the Gibbs sampler. The unknown parameters are the regression coefficients, the power in the Box–Cox transformation, the serial correlation coefficient, and the variance of the disturbance terms. In addition, we forecast the future technological substitution rate and its interval. Model validation and model choice issues are also addressed. Two numerical examples with real data sets are given.©1997 John Wiley & Sons, Ltd.     

Computation speedup in the dynamic simulation of MEMS by macromodels

A doubly clamped microbeam actuated by electrostatic force with squeezed gas film damping is a well-known and standard micro-device in microelectromechanical system (MEMS) for many researchers to demonstrate how reduced-order dynamic macromodel is an effective way to faithfully capture the device behaviors. However it still takes time to directly recompute the time-dependant nonlinear terms in macromodels which are generated by a proper orthogonal decomposition (POD) method with Galerkin procedure at every time step during the macromodel simulation. This paper proposes two methods for speeding up the computation of macromodel simulations. In the first method, the computation speedup is achieved based on the concept of precomputation upon the basis functions are available. In the second method, cubic splines approximation is used to interpolate the basis functions and their first and second derivatives, and spatial integration is performed by application of the Gaussian quadrature. Numerical results show both methods could enhance the efficiency of the macromodel simulation compared with our previous computation results     

污泥性质、胶羽结构与处置

污泥处置近来已成为极重要的环境问题。本文综述了污泥处置研究发展现况，论述了各种类型的污泥与其组成颗粒的特性、结构和污泥处置中的各种重要程序，并进一步讨论了污泥的后处理，如杀菌、水解、热处理与资源亿等，以及近年来对污泥胶羽结构研究的进展。     

一种基于可靠性的设备顺序预防性维护模型

等周期预防性维护策略不可避免地会使设备的可靠性随着役龄及维护次数的增加而逐步降低．为此,结合役龄递减因子和故障率递增因子的优点,通过引入基于两类调整因子的混合式故障率演化规则,建立了基于设备可靠性的顺序预防性维护优化模型,并以威布尔分布为例,利用蒙特卡罗仿真方法对其进行了优化．结果显示,该模型符合设备的实际维护情况,可为设备的维护决策提供有力的支持．     

降雨时黏性土边坡的离心模型试验

为研究降雨引起的黏性土边坡变形破坏,进行了边坡的降雨离心模型试验。试验中利用自主研制的离心场降雨模拟设备,用图像采集和相关分析方法,观测了降雨过程中土坡的破坏形态和位移场变化过程。结果表明:降雨对边坡稳定性产生很大影响。降雨引起均质土坡发生浅层土体滑移破坏,雨水入渗至土坡较深的位置。降雨引起土坡位移逐渐增大,且变形区域也逐渐扩展,最终形成明显的位移集中区域。土坡中一点位移发展可分为小位移阶段、迅速增大阶段和缓慢增大阶段。     

阳生与阴生环境梓树叶片的比较解剖学研究

采用光学显微技术,对不同生长环境的梓树Catalpa ovata G.Don叶片进行了比较解剖研究.结果表明:梓树的阳生叶比阴生叶大得多,为1.94～2.64倍;阳生叶的栅栏组织厚度是阴生叶的1.96倍左右.阳生叶的气孔微下陷,有利于减少水分蒸腾;阴生叶的气孔大部分微上拱.阳生叶的上表皮比阴生叶厚,为1.91倍左右;阳...     

用于手写签名识别的演化超网络

手写签名作为易被大众所接受的生物特征身份认证方式,已成为模式识别领域一个重要研究热点.针对现有手写签名存在易模仿难鉴定的问题,提出一种结合演化超网络模型的手写签名认证方法.为了平滑噪声,构造出可读性强的笔迹特征集,采用向量化和平滑采集点的方法对手写签名样本进行预处理,从而提取出位置和方向特征属性,采用演化超网络模型对签名进行学习和鉴定.为验证该方法的有效性,对20个签名用户分别采集了40个真实签名和20个伪造签名数据进行实验.实验结果表明,该方法对用户签名的误拒率(false rejection rate,FRR)为4.75％,误纳率(false acceptance rate,FAR)为3.75％,识别率(verification accuracy,VA)为95.75％.同时和其他传统的识别算法相比,具有更高的识别率.     

Extrusion Freeforming of Millimeter-Wave Electromagnetic Bandgap (EBG) Photonic Crystals

Extrusion freeforming can be used for the rapid prototyping of millimeter-wave electromagnetic bandgap (EBG) structures. In this work, an alumina-polymer paste with a relatively high volatility solvent (propanol) was used and the characteristics of the ceramic paste, particularly the rheological features are described. The advantage of high volatility solvent is that the viscosity and elastic modulus of the paste are increased sharply as the solvent evaporates. Thus, the rigidity of the extruded filament is quickly increased as a small amount of solvent evaporates. Finally, by employing this procedure, different EBG structures such as 2-D, 3-D woodpile and aperiodic structures were fabricated and their bandgaps were measured. The experimental results show that extrusion freeforming is a relatively simple and easy method to fabricate these woodpile structures with a bandgap in the 90-110 GHz region.     

西周天象和绝对年代

文章依据殷末和西周的天象记录，推定了武王伐纣年和西周诸王年代。根据“五星合聚”、“岁在鹑火”及“月相干支”的记载，得出天文受命元年是公元前１０５８年，伐纣之年为元前１０４６年。把“天再旦”现象解释为发生在郑州地方的日食的“懿王元年”算出是公元前９０３年，但公元前９２５年也有成为“懿王元年”的可能性。