Mode Analysis and Design of a Low-Loss Photonic Crystal 60 degrees Waveguide Bend

The guided modes of a two-dimensional photonic crystal straight waveguide and a waveguide bend are studied in order to find the high transmission mechanism for the waveguide bend. We find that high transmission occurs when the mode patterns and wave numbers match, while the single-mode condition in the waveguide bend is not necessarily required. According to the mechanism, a simply modified bend structure with broad high transmission band is proposed. The bandwidth is significantly increased from 19 to 116 nm with transmission above 90%, and covers the entire C band of optical communication.

On the performance analysis and design of a novel shared-layer integrated devices using RCE-p-i-n-PD/SHBT - art. no. 67820J

We have explored the shared-layer integration fabrication of an resonant-cavity-enhanced p-i-n photodector (RCE- p-i-n-PD) and a single heterojunction bipolar transistor (SHBT) with the same epitaxy grown layer structure. MOCVD growth of the different layer structure for the GaAs based RCE- p-i-n-PD/SHBT require compromises to obtain the best performance of the integrated devices. The SHBT is proposed with super-lattice in the collector, and the structure of the base and the collector of the SHBT is used for the RCE. Up to now, the DC characteristics of the integrated device have been obtained.

并行计算模型参数动态分析软件包设计

并行计算模型的发展引入越来越多的模型参数。对并行计算模型参数动态采集分析软件包DEMPAT的整体框架进行研究,实现基于硬件性能计数器的存储层次参数采集模块。实验表明,该模块能够准确快速地获取存储层次参数且具有较好的可移植性。

并行计算模型参数动态采集分析软件工具包DEMPAT的设计初探

根据目标平台体系结构尤其是存储系统组织结构的差异，并行计算模型可以分成三代：共享存储并行计算模型、分布存储并行计算模型和层次存储并行计算模型。并行计算模型从第一代发展到第三代的过程中引入了越来越多的模型参数，而且随着处理器与存储系统之间速度差的不断增大，把存储层次引入并行计算模型成为一个新的发展趋势。这在提高模型分析精确度的同时也导致了模型的分析工作越来越复杂，因此有必要设计一个能够对并行计算模型参数进行半自动的获取和分析工具包，以便辅助模型分析工作。 本文首先介绍并行计算模型的发展过程和每个模型涉及到的模型参数，在此基础上提出了我们的并行计算模型参数动态采集分析软件工具包（DEMPAT）及其整体框架，并对现有的基准测试工具进行了简要介绍。我们着重分析了存储层次参数采集模块的设计理论和方法，实现了基于PAPI的高速缓存和TLB参数采集工具，并在主流的平台上进行了相关实验。另外我们采集了两种三角矩阵求逆算法的动态访存行为和浮点运算次数，揭示了存储访问复杂性对算法性能的影响。从实验结果可以看出我们的采集工具具有较好的可用性和精确性，可以作为并行计算模型参数动态采集分析工具中一个重要的组成部分。

Triple-region structure for turbulent-flow in a square duct - a finite-element approach

The Reynolds-averaged Navier-Stokes equations for describing the turbulent flow in a straight square duct are formulated with two different turbulence models. The governing equations are then expanded as a multi-deck structure in a plane perpendicular to the streamwise direction, with each deck characterized by its dominant physical forces as commonly carried out in analytical work using triple-deck expansion. The resulting equations are numerically integrated using higher polynomial (H-P) finite element technique for each cross-sectional plane to be followed by finite difference representation in the streamwise direction until a fully developed state is reached. The computed results using the two different turbulence models show fair agreement with each other, and concur with the vast body of available experimental data. There is also general agreement between our results and the recent numerical works anisotropic k-epsilon turbulence model.

Composition and evolution of the V2r vorneronasal receptor gene repertoire in mice and rats

Pheromones are chemicals produced and detected by conspecifics to elicit social/sexual physiological and behavioral responses, and they are perceived primarily by the vomeronasal organ (VNO) in terrestrial vertebrates. Two large superfamilies of G protein-coupled receptors, V1rs and V2rs, have been identified as pheromone receptors in vomeronasal sensory neurons. Based on a computational analysis of the mouse and rat genome sequences, we report the first global draft of the V2r gene repertoire, composed of similar to 200 genes and pseudogenes. Rodent V2rs are subject to rapid gene births/deaths and accelerated amino acid substitutions, likely reflecting the species-specific nature of pheromones. Vertebrate V2rs appear to have originated twice prior to the emergence of the VNO in ancestral tetrapods, explaining seemingly inconsistent observations among different V2rs. The identification of the entire V2r repertoire opens the door to genomic-level studies of the structure, function, and evolution of this diverse group of sensory receptors. (c) 2005 Elsevier Inc. All rights reserved.

PIBG Toolkit:一个笔式界面工具箱的分析与设计

PIBG Toolkit是一个基于PIBG交互范式构造而成的笔式应用开发平台:PIBG Toolkit中包含了纸、框等多种交互组件，定义了纸、框和内容三个层次之间的静态结构和动态机制: 开发者开发笔式交互系统时，可以用PIBG Toolkit来建立整体的软件框架和交互机制，并有选择地在系统中添加Toolkit中所提供的交互组件.这样，开发者的精力将会集中在应用领域的内容上.目前，基于该平台已经开发出多个具有很好应用前景的笔式应用系统.

A four-phase confocal elliptical cylinder model for predicting the effective thermal conductivity of coated fibre composites

A four-phase confocal elliptical cylinder model is proposed from which a generalised self-consistent method is developed for predicting the thermal conductivity of coated fibre reinforced composites. The method can account for the influence of the fibre section shape ratio on conductivity, and the physical reasonableness of the model is demonstrated by using the fibre distribution function. An exact solution is obtained for thermal conductivity by applying conformal mapping and Laurent series expansion techniques of the analytic function. The solution to the three-phase confocal elliptical model, which simulates composites with idealised fibre-matrix interfaces, is arrived at as the degenerated case. A comparison with other available micromechanics methods, Hashin and Shtrikman's bounds and experimental data shows that the present method provides convergent and reasonable results for a full range of variations in fibre section shapes and for a complete spectrum of the fibre volume fraction. Numerical results show the dependence of the effective conductivities of composites on the aspect ratio of coated fibres and demonstrate that a coating is effective in enhancing the thermal transport property of a composite. The present solutions are helpful to analysis and design of composites.

加速器高频误差分析系统的设计与实现

兰州重离子加速器冷却储存环的控制系统由磁场电源控制系统、真空控制系统、高频控制系统等许多子控制系统所组成。 本文所论述的对象是高频控制系统。本文所研究的主要问题，就是如何在对高频信号合理采样后，从得到的数字信息中提取出信号的有用信息。采用普通的通信接收机结构难以实现对高频信号的分析，因此应用软件无线电接收机原理，针对高频信号的特殊情况，设计实现了一个高频信号信息的分析系统。系统主要使用DSP处理器

Oxalate decarboxylase from Agrobacterium tumefaciens C58 is translocated by a twin arginine translocation system

Oxalate decarboxylases (OXDCs) (E.C. 4.1.1.2) are enzymes catalyzing the conversion of oxalate to formate and CO2. The OXDCs found in fungi and bacteria belong to a functionally diverse protein superfamily known as the cupins. Fungi-originated OXDCs are secretory enzymes. However, most bacterial OXDCs are localized in the cytosol, and may be involved in energy metabolism. In Agrobacterium tumefaciens C58, a locus for a putative oxalate decarboxylase is present. In the study reported here, an enzyme was overexpressed in Escherichia coli and showed oxalate decarboxylase activity. Computational analysis revealed the A. tumefaciens C58 OXDC contains a signal peptide mediating translocation of the enzyme into the periplasm that was supported by expression of signal-peptideless and full-length versions of the enzyme in A. tumefaciens C58. Further site-directed mutagenesis experiment demonstrated that the A. tumefaciens C58 OXDC is most likely translocated by a twin-arginine translocation (TAT) system.