Performance of SBR-Modified Asphalt Yufeng Cong

A dose of SBR modifier added to asphalt can improve asphalt's performance in stability, permanence, viscosity, and resistance to aging. Better application performances of asphalt pavement are affected directly by proper SBR modifying. This paper shows some investigations that confirm the relationship between the addition of SBR with the structure and the properties of SBR-modified asphalt. This paper also discusses the modified asphalt high temperature property, low temperature ductility, and mechanism of SBR-modified asphalt. The addition of SBR modifier showed an increase in viscosity, softening point, and elastic recovery of modified asphalt with rising temperature. When the temperature rises, the improvement of SBR-modified asphalt in softening point, elastic recovery, and visco-toughness result from SBR cross-linking. Although the lengths of low temperature ductility of SBR-modified asphalt are increased, the viscosities of modified asphalt increase; however, the softening point between the upper layer and lower layer were about 1.8°C after the isolated experiment.     

A new technique for boosting efficiency of silicon solar cells

A new type of photovoltaic system with higher generation power density has been studied in detail. The feature of the system is a V-shaped module (VSM) with two tilted monocrystalline solar cells. Compared to solar cells in a flat orientation, the VSM enhances external quantum efficiency and leads to an increase of 31% in power conversion efficiency. Due to the VSM technique, short-circuit current density was raised from 24.94 to 33.7 mA/cm², but both fill factor and open-circuit voltage were approximately unchanged. For the VSM similar results (about 30% increase) were obtained for solar cells fabricated by using mono-crystalline silicon wafers with only conventional background impurities.     

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.     

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。     

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。