Improving imprinted shape cavities of molecularly imprinted sol–gel host matrix with minimal relaxation for sensing of creatinine

Journal of Sol-Gel Science and Technology - Molecularly imprinted polymer (MIP) is of great attention in biomimetic recognition systems due to its selective molecular recognition towards any guest...     

混合von Mises 模型的参数估计

有限混合von Mises模型在天文学、生物学、地理和医药等许多领域都有重要的应用．可是,不论样本量有多大,此模型的似然函数都是无界的．因此,参数的最大似然估计(MLE)是不相合的．我们发现,与混合正态模型一样,上述困难可以通过引入关于分布浓度参数的一个惩罚函数或对参数空间添加适当的约束来克服．在此文中,我们从理论上证明了这两种方法是可行的,相应的参数估计是强相合的,且是渐近有效的．我们还通过计算机模拟来探讨这些新方法在有限样本情况下的统计性质,并与现有的矩估计作了比较．结果发现,惩罚极大似然估计在均方误差方面表现最佳．最后我们还分析了一组实际数据,以进一步介绍新的估计方法．     

Fast evaluation of polyharmonic splines in three dimensions

M. J. D. Powell ^{This paper concerns the fast evaluation of radial basis functions.It describes the mathematics of hierarchical and fast multipolemethods for fast evaluation of splines of the form where is a positive integer andp is a low-degree polynomial. Splines s of this form are polyharmonicsplines in 3 and have been found to be very useful for providingsolutions to scattered data interpolation problems in 3. Asit is now well known, hierarchical methods reduce the incrementalcost of a single extra evaluation from O(N) to O(log N) operationsand reduce the cost of a matrix–vector product (evaluationof s at all the centres) from O(N2) to O(N log N) operations.We give appropriate far- and near-field expansions, togetherwith error estimates, uniqueness theorems and translation formulae.A hierarchical code based on these formulae is detailed andsome numerical results are given.}     

非化学计量配比La0.67Sr0.33-x□xMnO3的结构和输运性质的研究

利用固相反应法制备了非化学计量配比的类钙钛矿锰氧化物La_0.67Sr_0.33-x□_xMnO₃(0<x≤0.33),研究了A位空位对材料的晶体结构和输运性质的影响.对粉末X射线衍射谱的Rietveld全谱拟合表明样品均为单相,在x=0到x=0.33空位浓度范围内晶体对称性没有发生变化,均具有三方对称性,空间群为R3c< 关键词： 非化学计量配比锰氧化物 Rietveld全谱拟合 结构分析 输运性质     

External-cavity birefringence feedback effects of microchip Nd:YAG laser and its application in angle measurement

External-cavity birefringence feedback effects of the microchip Nd:YAG laser are presented. When a birefringence element is placed in the external feedback cavity of the laser, two orthogonally polarized laser beams with a phase difference are output. The phase difference is twice as large as the phase retardation in the external cavity along the two orthogonal directions. The variable extra-cavity birefringence, caused by rotation of the external-cavity birefringence element, results in tunable phase difference between the two orthogonally polarized beams. This means that the roll angle information has been translated to phase difference of two output laser beams. A theoretical analysis based on the Fabry--Perot cavity equivalent model and refractive index ellipsoid is presented, which is in good agreement with the experimental results. This phenomenon has potential applications for roll angle measurement.     

A Hybrid Multiobjective Evolutionary Algorithm for Solving Vehicle Routing Problem with Time Windows

Vehicle routing problem with time windows (VRPTW) involves the routing of a set of vehicles with limited capacity from a central depot to a set of geographically dispersed customers with known demands and predefined time windows. The problem is solved by optimizing routes for the vehicles so as to meet all given constraints as well as to minimize the objectives of traveling distance and number of vehicles. This paper proposes a hybrid multiobjective evolutionary algorithm (HMOEA) that incorporates various heuristics for local exploitation in the evolutionary search and the concept of Pareto's optimality for solving multiobjective optimization in VRPTW. The proposed HMOEA is featured with specialized genetic operators and variable-length chromosome representation to accommodate the sequence-oriented optimization in VRPTW. Unlike existing VRPTW approaches that often aggregate multiple criteria and constraints into a compromise function, the proposed HMOEA optimizes all routing constraints and objectives simultaneously, which improves the routing solutions in many aspects, such as lower routing cost, wider scattering area and better convergence trace. The HMOEA is applied to solve the benchmark Solomon's 56 VRPTW 100-customer instances, which yields 20 routing solutions better than or competitive as compared to the best solutions published in literature.     

Near-field radiative heat transfer between two plane surfaces with one having a dielectric coating

The effect of a dielectric coating on the near-field radiative heat transfer between two plane surfaces is numerically studied in the framework of the fluctuational electrodynamics. The dielectric coating is assumed to be a SiC or SiO₂ film, which is on top of the emitter. The results show that the near-field radiative flux between the plane surfaces can be either diminished or enhanced by the dielectric coating, depending on the thermal radiative properties of the emitter and the receiver. Furthermore, the dielectric coating effect on the near-field radiative flux can be very different from that on the far-field radiative flux. Detailed analysis on the variations of the TE- and TM-wave components of the radiative flux by adding the dielectric coating is provided, along with the physical mechanisms that account for these changes. Dielectric coatings such as SiC and SiO₂ films are widely seen in microelectronic structures and nanofabrication devices. The results obtained in this work should be valuable for further study and nanotechnological applications of near-field radiative heat transfer.     

基于热传导原理电枢平均磨损率计算

在假设导轨为半无限长固体导体及电枢表面磨损主要是熔化磨损条件下,基于固体接触面导热原理,推导出电枢和导轨温度分布方程,提出了电枢平均磨损率计算方法。利用此方法分析了驱动电流、电枢和导轨材料匹配和接触面积参数对电枢平均磨损率影响。将平均磨损率计算结果与Stefani和Parker的实验结果进行对比,二者吻合较好,从而为建立电磁轨道炮磨损率与转捩之间的关系提供理论支持。     

Laser writing techniques for photomask fabrication using a femtosecond laser

Photomasks are the backbone of microfabrication industries. Currently they are fabricated by a lithographic process, which is very expensive and time consuming since it is a multi-step process. These issues can be addressed by fabricating photomasks by direct femtosecond laser writing, which is a single-step process and comparatively cheaper and faster than lithography. In this paper we discuss our investigations on the effect of two types of laser writing techniques, namely front- and rear-side laser writing, with regard to the feature size and the edge quality of a feature. It is proved conclusively that for the patterning of masks, front-side laser writing is a better technique than rear-side laser writing with regard to smaller feature size and better edge quality. Moreover the energy required for front-side laser writing is considerably lower than that for rear-side laser writing. Received: 22 May 2001 / Accepted: 14 September 2001 / Published online: 17 October 2001