Hreels of methanol oxidation on polycrystalline silver: Spectroscopic evidence for adsorbed intermediates in the conversion of methoxide to formaldehyde and water

The adsorption and the decomposition of methanol on an oxygen precovered polycrystalline silver surface were characterized by high resolution electron energy loss spectroscopy. A stable methoxy species and subsequently two new intermediates related to the decomposition of methoxy have been isolated and identified by temperature profiled ELS.     

长直SiO_2纳米线的制备和结构表征

采用磁控溅射法,以Si粉和溅金Si(111)为原料,加入C粉,在Si(111)衬底上制备无定形SiO2纳米线。首先,在Si(111)衬底上分别溅射厚度为18和36 nm的Au。然后,在1 100℃条件下处理80 min。用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、傅里叶红外光谱(FTIR)和X射线衍射方法 (XRD)等测试手段对退火后的SiO2纳米线的表面相貌、微观结构进行分析。结果表明,反应后有大量长而直的SiO2纳米线生成。而且随着溅射Au厚度的增加,SiO2纳米线的数量增多,且长度更长。这表明,SiO2纳米线的生长与溅射Au的厚度密切相关。     

Improving Transport Layer Performance in Multihop Ad Hoc Networks by Exploiting MAC Layer Information

The traditional TCP congestion control mechanism encounters a number of new problems and suffers a poor performance when the IEEE 802.11 MAC protocol is used in multihop ad hoc networks. Many of the problems result from medium contention at the MAC layer. In this paper, we first illustrate that severe medium contention and congestion are intimately coupled, and TCP's congestion control algorithm becomes too coarse in its granularity, causing throughput instability and excessively long delay. Further, we illustrate TCP's severe unfairness problem due to the medium contention and the tradeoff between aggregate throughput and fairness. Then, based on the novel use of channel busyness ratio, a more accurate metric to characterize the network utilization and congestion status, we propose a new wireless congestion control protocol (WCCP) to efficiently and fairly support the transport service in multihop ad hoc networks. In this protocol, each forwarding node along a traffic flow exercises the inter-node and intra-node fair resource allocation and determines the MAC layer feedback accordingly. The end-to-end feedback, which is ultimately determined by the bottleneck node along the flow, is carried back to the source to control its sending rate. Extensive simulations show that WCCP significantly outperforms traditional TCP in terms of channel utilization, delay, and fairness, and eliminates the starvation problem     

西部城乡中学体育教育资源配置的系统优化

本文对西部城乡中学体育教育资源的配置情况进行了分析,并对其配置进行了优化分析。体育资源配置的优化分析采用基于B/S结构的资源配置系统,并对系统进行了设计,对TCP/IP协议这项技术进行相关分析。     

Efficient Polymer Solar Cells with a High Open Circuit Voltage of 1 Volt

A series of polymers containing benzo[1,2‐b:4,5‐b′]dithiophene and N‐alkylthieno[3,4‐c]pyrrole‐4,6‐dione are designed. By incorporating different alkylthienyl side chains, the fill factor (FF) and open circuit voltage (V_oc) of the copolymers are further improved. The experimental results and theoretical calculations show that the size and topology of the side chains can influence the polymer solubility, energy levels, and intermolecular packing by altering the molecular coplanarity. As a result of improved morphology and fine‐tuned energy levels, an increased FF and a high V_oc of 1.00 V are achieved, as well as a power conversion efficiency of 6.17%, which is the highest efficiency ever reported for polymer solar cells with a V_oc over 1 V.     

变频器在恒压供水上的应用

简要介绍了JP6C—AP1变频器的特点及在恒压供水上的应用。     

数据中继卫星系统的数据传输协议研究

首先介绍了美国中继卫星系统的基本概况,给出了其系统组成框图和连接关系,依据中继卫星系统数据传输任务和数据传输需求,并在分析比较ESA和CCSDS的星地数据传输管理协议的基础上,提出了使用CCSDS组织的AOS建议书作为数据中继卫星系统的数据传输协议建议,给出了数据传输帧的定义和初步操作建议。     

An Investigation on the Coupled Thermal–Mechanical–Electrical Response of Automobile Thermoelectric Materials and Devices

Thermoelectric (TE) materials, which can directly convert heat to electrical energy, possess wide application potential for power generation from waste heat. As TE devices in vehicle exhaust power generation systems work in the long term in a service environment with coupled thermal–mechanical–electrical conditions, the reliability of their mechanical strength and conversion efficiency is an important issue for their commercial application. Based on semiconductor TE devices wih multiple p–n couples and the working environment of a vehicle exhaust power generation system, the service conditions of the TE devices are simulated by using the finite-element method. The working temperature on the hot side is set according to experimental measurements, and two cooling methods, i.e., an independent and shared water tank, are adopted on the cold side. The conversion efficiency and thermal stresses of the TE devices are calculated and discussed. Numerical results are obtained, and the mechanism of the influence on the conversion efficiency and mechanical properties of the TE materials is revealed, aiming to provide theoretical guidance for optimization of the design and commercial application of vehicle TE devices.     

Braille document recognition using Belief Propagation

There is a significant need for a system to recognize Braille documents in order to preserve them and make them available to a larger group of visually impaired people. A new system for Braille document recognition is proposed. We introduce a highly-adaptive Braille documents parameters estimation method to automatically determine the rotation angle, indentations, and spacing in both vertical and horizontal orientation. The key element in determining the rotation angle of the images is based on Radon transform. Also we introduce the method of Braille translation using Belief Propagation on the assumption that the Braille document is a Hidden Markov Model. We demonstrate the effectiveness of rotation angle correction as well as the accuracy of indentation and spacing in both orientations. We also prove that the translation algorithm is efficient and robust to errors made in the dot detection. The proposed method may be used for further applications.     

全业务时代,集团业务建设思考

讨论全业务时代集团业务发展的新要求,分析现行支撑系统的不足,分析构建以集团客户为中心,优化流程,促进协同运作,灵活配置等特点的全业务支撑体系的重要性,给出对新形势下集团业务建设的建议。