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Based on the capacity/demand (C/D) analysis of bridge components, and life cycle and performance based seismic design principles, a practical approach is developed for the seismic performance evaluation of super-long span cable-stayed bridges. According to the approach, the seismic performance evaluation of the Sutong Bridge, which is a cable-stayed bridge with a main span of 1 088 m, is completed, and the practicality of the approach is validated. The earthquake resistance level for super-long span cable-stayed bridges is discussed, including the earthquake level, its corresponding structural performance and check indices. And a set of formula for capacity/demand ratio calculation of bridge components is proposed. 相似文献
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XIEChang-sheng LIURui-fang TANZhi-hu 《武汉大学学报:自然科学英文版》2004,9(6):890-894
This paper presents a novel hierarchy cache architecture for the purpose of optimizing IO performance. The main idea of the hierarchy cache is to use a few megabytes of RAM and a pagefile to form a two-level cache architecture. The pagefile is equivalent to the cache disk in DCD(Disk Caching Disk). The pagefile outperforms data disks, because data are accessed in different units and different ways. Small writes are collected in the RAM cache first, and data will be transferred to the pagefile in large writes later. When the system is idle, it will destage data from the pagefile to data disks. The performance test results show that the hierarchy cache can improve IO performance dramatically for small writes, and the mail server using the hierarchy cache driver can handle transactions about 2.2 times faster than the normal mail server. The hierarchy cache is implemented as a filter driver, so it‘s transparent to the current Windows 2000/Windows XP operating system. 相似文献
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Y.Ohnishi K.Iwasaki H.Mizuta T.Sudo S.Muto T.Shima T.Tanaka K.Ito M.Umezu 《上海大学学报(自然科学版)》2004,10(B10):32-36
The purpose of this research is to develop an inexpensive pulsatile blood pump system for short-term use, as a combination of the usage of IABP console and spiral vortex pump. In vitro hydrodynamic test and in vitro hemolysis test were conducted to check the practical performance. 相似文献
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The alignment between information systems (IS) and business strategy along with its implications for perceived IS effectiveness and business performance is an important question, which is rarely studied in China. Based on an empirical study, this paper summarized the significance of IS strategic alignment and its impact on business performance. This study also measured business strategy, information system strategy, and information system strategic alignment, built a conceptual model to describe the relationship between these factors, and investigated their implications for information system performance and business performance. A structural equation model was employed to test the conceptual model. Analyses of data gathered in a survey indicate that information system strategic alignment is a better predictor of business performance than business strategy or information system strategy alone, although business strategy can significantly influence business performance. 相似文献
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Electrochemical characterization of MnO2 as the cathode material for a high voltage hybrid capacitor
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Manganese dioxide (MnO2) was prepared using the ultrasonic method. Its electrochemical performance was evaluated as the cathode material for a high voltage hybrid capacitor. And the specific capacitance of the MnO2 electrode reached 240 F·g-1. The new hybrid capacitor was constructed, combining A1/Al2O3 as the anode and MnO2 as the cathode with electrolyte for the aluminum electrolytic capacitor to solve the problem of low working voltage of a supercapacitor unit. The results showed that the hybrid capacitor had a high energy density and the ability of quick charging and discharging according to the electrochemical performance test. The capacitance was 84.4 μF, and the volume and mass energy densities were greatly improved compared to those of the traditional aluminum electrolytic capacitor of 47 μF. The analysis of electrochemical impedance spectroscopy (EIS) showed that the hybrid capacitor had good impedance characteristics. 相似文献
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Investigation of the medium calcium based non-burnt brick made by red mud and fly ash: durability and hydration characteristics
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Ying-tang Xu Bo Yang Xiao-ming Liu Shuai Gao Dong-sheng Li Emile Mukiza Hua-jian Li 《矿物冶金与材料学报》2019,26(8):983-991
Red mud is a type of highly alkaline waste residue produced in the process of alumina smelting by the Bayer process. Based on the idea of medium calcium content, solid wastes such as red mud and fly ash were used to prepare non-burnt bricks; and the mass ratio of CaO/SiO2 was selected in the range of 0.88-1.42. Mechanical properties and durability were investigated with a compressive strength test. X-ray diffractometry (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) techniques were used to characterize the hydration characteristic. The environmental performance was analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP). The results indicated that the mechanical properties and the durability were optimal when the mass ratio of CaO/SiO2 was 1.23. The hydration products were mostly C-S-H gel, ettringite, Na4Ca(Si10Al16)O32·12H2O and Ca3Al2(SiO4)(OH)8. They were responsible for the strength development, and the CaO/SiO2 mass ratio of 1.23 had the best polymerized structure. The results of an environmental performance test showed that the heavy metals in the raw materials were well-solidified in the brick. Therefore, this paper provides an effective solution for use of solid wastes in building material. 相似文献
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A supercapacitor based on charge storage at the interface between a high surface area carbon nanotube electrode and a LiClO4/PC electrolyte was assembled. The performance of the capacitor depends on not only the material used in the cell but also the construction of the cell. From a constant charge-discharge test, the capacitance of 60 F was obtained. The performance of the power capacitor for pulse power sources was described. The specific energy (0.8 W·h·kg-1) and the specific power (0.75 kW·kg-1) of the power supercapacitor were demonstrated with a cell of the maximum operating voltage of 2.5 V. A hybrid power source consisting of a lithium ionic battery and the 60 F supercapacitor was demonstrated to power successfully a simulated power load encountered in GSM portable communication equipment. The addition of the supercapacitor to the power train of a cellular phone results in significantly more energy from the battery being used by the load. The experiments indicate that more than 33.8% energy is utilized by load and less stored energy is dissipated within the battery for each charge-discharge cycle. 相似文献
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ZHAODa-yuan JIANGYi-xin LINChuang LIYan-xi 《武汉大学学报:自然科学英文版》2005,10(1):98-102
We mainly explore two problems when combining IPS, ec module into TCP/IP stack by porting the famous IPSec software (FreeS/WAN) into a security gateway. One is how to implement the IPS, ec module based on Nerfilter in Linux 2.4. x kernel. The other problem is the performance evaluation. We test thc throughput of our security gateway before and after applying IPSec with different encryption/decryption algorithms, including the software-based and hardware-based method. With these testing data, we analyze further system performance bottleneck. In the end, we also infer the quantitative relation between the system throughput and the speed of encryption/decryption algorithm and propose some valuable conclusions for improving performance. 相似文献
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Hybrid Electric Vehicle (HEV) becomes a popular research project all over the world because of its high efficiency and low emissions. HEV is driven by Internal Combustion (IC) engine and electric motor,and its powertrain is more complex than conventional vehicle. Therefore, the complexity of a HEV power-train demands a rehable control strategy be developed to guarantee stable and consistent operation. In this paper, EACS is proposed which takes IC engine as a main power unit and the electric motor as an assis-tant one. Because the fuel consumption of HEV mainly depends on IC engine, EACS restricts the IC en-gine to operate under the condition with favorable fuel economy. In the paper several control parameters are described such as the maximum torque, the lowest and highest desired battery state of charge (SOC),whose values will affect the performance of HEV remarkably. In addition, the test models of power units for HEV, mathematical models of transmission and vehicle dynamics for HEV are estabhshed. A forward-facing simulation software (i.e. driver-to-wheel) based on MATLAB/Simulink is developed to test the performance of EACS and determine the proper value of the control parameters. The simulation results and conclusion are also shown in the paper. 相似文献
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Fu Xu Xiaolong Mo Sen Wan Changqing Jiang Hongwei Hao Luming Li 《科学通报(英文版)》2014,(29):3831-3834
Carbon nanotube yarns (CNTY) possess good specific strength and specific conductivity. As such, their potential for commercial applications is significant. Fatigue performance is a significant consideration in yarn/wire applications. In this study, the flexural fatigue performance of CNTY spun from super-aligned carbon nanotube arrays was investigated using a reversed bending test. The results showed that CNTY exhibited excellent resistance to pure flexural fatigue, significantly outperforming stainless steel wire; CNTY failed where a combination of flexural fatigue and tension-tension fatigue had special hollow fracture morphology, and CNTY resistance remained fundamentally unchanged in the combination fatigue process. 相似文献
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LBS软件平台的实现技术 总被引:3,自引:1,他引:3
基于位置服务的应用,种类繁多且市场巨大,因此,有必要开发一个平台软件,以便在此平台上高效地开发出各种LBS应用软件。阐述了采用组件技术开发LBS软件平台能够适应长期持续的LBS应用开发的必然性,给出了组件式LBS软件平台的体系结构,讨论了LBS核心组件的功能。所提供的基本接口和核心功能适用于不同的移动通信网,能支持LBS应用的开发、定制和扩充,避免了重复开发。,,, 相似文献
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现有位置服务(LBS)应用平台都采用基于中间件或组件对象的分布式计算模式,要求LBS用户必须与系统特续稳定连接,而在带宽有限的移动网络环境中,无法确保用户在使用过程中能够达到持续稳定的网络连接。为此,提出利用移动Agent来构建LBS应用平台,以便能够实时有效地为LBS移动用户提供各种信息服务。平台采用两层业务结构为基础来设计基于知识库管理的移动Agent;利用启发式动态路径串行迁移策略来实现Agent的移动;采用基于Home Agent的消息特发方式来实现Agent之间的相互通信;采用XML和GML来实现LBS各种数据的集成;并结合Applet采实现LBS信息的SVG或XML数据客户端显示。系统原型的实现验证了该方案的可行性。 相似文献
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基于多源LBS数据的职住平衡对比研究 ——以北京城区为例 总被引:1,自引:0,他引:1
采用多源LBS数据(热力图数据、POI数据、微博签到数据), 对北京城区职住关系进行测定和分析, 从不同角度测度北京城区职住关系的时间和空间特征, 研究结果可为改善城市职住关系提供决策参考。比较了LBS数据同传统人口和经济普查数据所测度的职住关系结果的差异性, 讨论差异产生原因, 为更好地利用LBS数据进行职住关系研究提供建议。 相似文献
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摘!要#现有位置服务(LBS)应用平台都采用基于中间件或组件对象的分布式计算模式,要求LBS用户必须与系
统持续稳定连接,而在带宽有限的移动网络环境中,无法确保用户在使用过程中能够达到持续稳定的网络连接。
为此,提出利用移动Agent来构建LBS应用平台,以便能够实时有效地为LBS移动用户提供各种信息服务。平台
采用两层业务结构为基础来设计基于知识库管理的移动Agent;利用启发式动态路径串行迁移策略来实现Agent
的移动%采用基于Home Agent的消息转发方式来实现Agent之间的相互通信;采用X 相似文献
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LBS在数字景区中的应用设计 总被引:1,自引:0,他引:1
从数字景区移动位置服务(Location Base Service,LBS)需求入手,探讨了数字景区LBS系统体系框架.归纳、列举、比较了目前移动定位技术、移动通讯技术、移动操作系统平台以及各平台下移动LBS应用程序开发的难易程度.分析了景区LBS的工作流程,试验了在WindowsMobile平台下开发数字景区LBS应... 相似文献
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随着移动定位技术的飞速发展,追踪移动对象以提供定位服务(locationbased services, LBS)已变得切实可行。一般地,定位服务器被构建为一个移动对象数据库。主要讨论在移动对象数据库中查询时空数据的相关核心技术,包括数据模型、索引结构。并给出了一种可用于LBS环境下的相关实现。 相似文献