Land-based mobile mapping system with its applictions for the Olympic Games

There is a trend for rapid spatial data capture supported by integration of multiple platforms and multiple sensors. This paper presents the principles and technologies of land-based mobile mapping systems based on an integration of remote sensing, GPS and GIS technologies. The innovations and advantages of the integrated system are described. The analytic model and error model of a mobile mapping system are proposed and the application interface of digital measurable images is also discussed. A Truemap Engine with Plug-in and API is designed to manage a huge volume of stereo image series from a land-based mobile mapping system so that other geographic information systems （GIS） engines can freely use the sequence of stereo images. The applications of digital measurable images （DMI） as well as mobile mapping systems in the Olympic Games in Beijing, 2008 are presented.     

Multi-type sensor placement and response reconstruction for structural health monitoring of long-span suspension bridges大跨悬索桥结构健康监测多种传感器布置和响应重构的方法

This study is devoted to the experimental validation of the multi-type sensor placement and response reconstruction method for structural health monitoring of long-span suspension bridges. The method for multi-type sensor placement and response reconstruction is briefly described. A test bed, comprising of a physical model and an updated finite element(FE) model of a long-span suspension bridge is also concisely introduced. The proposed method is then applied to the test bed; the equation of motion of the test bed subject to ground motion, the objective function for sensor location optimization, the principles for mode selection and multi-type response reconstruction are established. A numerical study using the updated FE model is performed to select the sensor types,numbers, and locations. Subsequently, with the identified sensor locations and some practical considerations, fiber Bragg grating(FBG) sensors, laser displacement transducers, and accelerometers are installed on the physical bridge model. Finally, experimental investigations are conducted to validate the proposed method. The experimental results show that the reconstructed responses using the measured responses from the limited number of multitype sensors agree well with the actual bridge responses.The proposed method is validated to be feasible and effective for the monitoring of structural behavior of longspan suspension bridges.     

Improved Active Vibration Isolation Systems

The control force, feedback gain, and actuator stroke of several active vibration isolation systems were analyzed based on a single-layer active vibration isolation system. The analysis shows that the feedback gain and actuator stroke cannot be selected independently and the active isolation system design must make a compromise between the feedback gain and actuator stroke. The performance of active isolation systems can be improved by the joint vibration reduction using an active vibration isolation system with an adaptive dynamic vibration absorber. The results show that the joint vibration reduction method can successfully avoid the compromise between the feedback gain and actuator stroke. The control force and the object vibration amplitude are also greatly reduced.     

Empirical modeling of nonlinear and hysteresis characteristics of the shock absorber

An empirical hybrid shock absorber model capable of capturing nonlinear and hysteresis charac- teristics of shock absorbers is built. The nonlinear characteristics are modeled by algebraic function and the hysteresis effects between shock force and shock velocity are modeled by neural network. To develop the empirical hybrid shock absorber model, a Mazda CX-7 front shock absorber is tested by a displacement-controlled hydraulic shock absorber testing machine. The hybrid shock absorber model is built and validated using the experimental shock absorber data. The RMS value for the hy- brid shock absorber model is 60.28N at the velocity range from - 1.3m/s to 1.3m/s.     

Empirical Research on User Acceptance of Mobile Searches

The mobile search, a combination of a web search engine and a mobile communication system, is viewed as the most influential application in the 3G era. Therefore, mobile search service providers are eager to know which factors most influence user acceptance of mobile searches. Based on the characteristics of mobile searches and a review of previous information technology acceptance research, this study integrates the task technology fit model and the unified theory of acceptance and use of technology model to develop a mobile search acceptance model and empirically tests this model. This study finds that, for mobile searches, the performance expectancy, social influence, and perceived cost all significantly influence use intention and the performance expectancy increases with the increasing user’s experience and higher task technology fit degree. The effort expectancy is found to not affect the use intention of mobile searches and the users’ gender does not have a significant moderating effect on the use intention. The results are then used to develop suggestions for mobile search providers to promote their application and development.     

Study on the application of active balancing device to solve the vibration problem for the rotor with bending fault

The rotor with bending faults that occurrs on the rotating machinery usually vibrates seriously. This paper investigates to apply the active balancing device on a flexible rotor with bending faults to solve the vibration problem. Two problems are studied by finite element method firstly： Where the balance actuator is fixed on the shaft and how much the balancing capacity of the active balancing device is needed. The experiment is then carried out on the test rig, which consists of a flexible rotor with bending faults. The test results indicate that the bending rotor peak vibration response can be decreased from 550~m to 40~tm below by using the active balancing device. The peak vibration response decreases approximately by 93 %. The synchronous vibration due to the rotor bending faults can be controlled effectively by using ac- tive balancing device. The active balancing device is especially adapted to solve the problem caused by thermal distortion with time-variation and randomness, which is varied with working conditions, thus it has good practical value in practice.     

Vibration Analysis of Digital Radiography System for Large Container Inspection

The cantilever vibration characteristics of a digital radiography system were analyzed to predict the effect of vibration on the performance of a mobile container inspection system. The static deformation,vibration mode and natural frequency of the cantilever of the digital radiography system were calculated with the ALGOR Finite Element System to verify the strength and rigidity of the cantilever. The maximum amplitude of the cantilever vibration occurs as it starts accelerating. The predictions show good agreement with test results, indicating that the finite element model of the cantilever structure accurately models the mechanical characteristics.     

Interaction between adjacent left-lateral strike-slip faults and thrust faults: the 1976 Songpan earthquake sequence

Based on the published focal mechanisms we have built the fault model of the main shocks of the 1976 Songpan earthquake sequence and calculated the coseismic Coulomb stress changes in the region. The results show that most of the aftershocks had occurred in the region where the Coulomb stresses had been increased, indicating a triggering relationship between the main shocks and the aftershocks. We also show that the first main shock （Ms = 7.2）, which is a left-lateral slip event, had increased the Coulomb stresses by 5×10^5 Pa at the second main shock （a thrust event with Ms = 6.7）. Therefore, we conclude that the first main shock had triggered the second main shock. The third main shock is also a left-lateral event, however, the triggering relationship between the third main shock and the previous two events is less obvious. General model calculations show that there is a good triggering relationship between adjacent left-lateral slip fault and thrust fault, but triggering between parallel slip faults is rather weak.     

A new provably-secure key agreement protocol for roaming in mobile networks

Protocols for authentication and key establishment have special requirements in a wireless environment. This paper presents a new key agreement protocol HAKA （home server aided key agreement） for roaming scenario. It is carried out by a mobile user and a foreign server with the aid of a home server, which provides all necessary authentications of the three parties. The session key can be obtained by no one except for the mobile user and the foreign server. HAKA is based on Diffie-Hellman key exchange and a secure hash function without using any asymmetric encryption. The protocol is proved secure in Canetti-Krawczyk （CK） model.     

一种硬盘动态电源管理方法

在便携式系统中,硬盘能耗约占整个系统能耗的20%.为降低系统能耗,提高系统使用时间,提出了一种硬盘动态电源管理方法:通过读写硬盘寄存器来实现硬盘状态的转换,读取内核相关结构以获取硬盘负载,设计并实现高性能的动态电源管理策略优化算法.实验结果表明,对硬盘进行动态电源管理,能显著降低便携式系统的能耗,证明文中提出的方法是可行的.     

硬盘动态电源管理的实现方法

越来越多的嵌入式设备系统利用电池供电,而电池容量有限,故有必要通过电源管理来降低功耗,从而延长系统的可持续使用时间。硬盘在嵌入式系统特别是移动设备如笔记本电脑等的能耗中占据了相当大的比重,通过对硬盘进行电源管理能够显著地降低系统能耗。论文介绍了硬盘动态电源管理(DPM)的设计与实现,包括硬盘状态的转换,负载获取以及的策略优化算法的设计与实现,并在具体硬盘上进行了实验,实现了基于不同DPM策略优化算法的动态电源管理。实验的结果与预期结果相符合,达到了节省硬盘能耗的目的,由此证明了该论文所介绍的硬盘动态电源管理实现过程的可行性。     

模型参考控制在两级驱动伺服系统中的应用

基于计算机硬盘的两级驱动伺服系统，采用模型参考控制改善VCM伺服环的输出，并将其回馈给MA伺服环作为输入，利用MA高频宽、响应快等优点，调节VCM输出及位置误差信号，获得较为理想的复合输出结果。实验仿真结果验证了本文控制算法的有效性。     

圆盘振动的主动控制

应用非接触式的电磁作动器，采用模拟器件设计了一整套圆盘横向振动的主动控制系统，并对圆盘进行了振动主动控制实验．其特点是能发出大的控制力、非接触传感，其中功率放大电路具有响应从直流到交流信号很宽频率的响应范围．该系统结构简单，具有较好的控制效果．     

书本式分布作动器及可控约束阻尼层结构控制的实验研究

利用压电材料的逆压电效应,研制了一种新型压电作动器———书本式分布作动器,讨论了作动器的附加位置,采用比例反馈进行了主动控制试验,通过试验给出了单位电压的控制效果与书本式分布作动器的压电片层数的关系．研究结果表明,书本式分布作动器是一种能在较低驱动电压下产生较大作动力的作动器,它和约束阻尼层结合构成的可控约束阻尼层主被动一体化控制技术对于薄壁结构振动的抑制效果显著,有着较好的工程应用前景     

轴向运动弦线横向振动的变结构控制

运用变结构控制理论,采用指数趋近律对张紧臂的角位移进行控制,从而达到控制轴向运动弦线横向振动的目的.利用Matlab进行数值仿真,验证了所提控制力的有效性.     

等飞高磁头的研究

本文研究两种ＴＰＣ型磁头的静态浮动特性,并利用其特殊性质,适当地选取摇臂式取数臂的长度及初始ＹＡＷ角,设计了一种适用于１３０ｍｍ（５１／４＂）盘的等飞高磁头。计算表明,在整个磁头寻道过程中,头盘间隙就动量不超过５ｎｍ,并且侧倾角也相当小。     

非均匀来流条件下偏心涡轮转子的气流激振力和动力特性

转子的偏心与非均匀来流都会使得涡轮内的流动变得周向非均匀,从而产生气流激振力作用于转子。以轴流涡轮为研究对象,对双耦合激励盘模型的叶片尺度子模型进行了简化,利用简化模型分析了转子偏心和非均匀来流所产生的气流激振力。将偏心转子的分析结果与试验结果进行了比较,验证了简化模型的正确性。在此基础上就非均匀来流对偏心涡轮转子动力特性的影响进行了分析,讨论了受迫振动的位移响应和自激振动的稳定性条件。结果表明,在一定条件下,非均匀的来流也会对转子系统的运动稳定性造成影响。     

一种微硬盘半自伺服刻写机制与实现方法

基于部分伺服刻写的思想,提出了一种微硬(磁)盘半自伺服刻写实现方法--螺旋伺服刻写方法.该方法首先将伺服初始信息以螺旋道的方式写入盘片,然后在非净室环境下由硬盘驱动器(HDD)通过其头盘组件自行将伺服信息补充完整.给出了螺旋伺服刻写的运动模型,建立了磁头精密定位控制系统.在现有的伺服刻写设备基础上,采用此伺服刻写方法可保证伺服信息的完整性,同时大大提高了净室的利用率,加快了伺服信息刻写速度,提高了生产效率,减少了昂贵伺服刻写设备的使用时间,降低了生产成本.     

一类不确定线性系统区域稳定的可靠控制

针对具有不确定性的线性定常系统,提出了考虑执行器故障的圆盘极点可靠配置问题·在更一般、更实际的执行器故障模型的基础上,给出了将极点配置到指定圆盘内可靠控制存在的充分条件·通过求解LMI完成状态反馈可靠控制器的设计·利用仿真实例验证了本文提出设计方法的可行性,并且通过与不考虑故障和不确定因素的系统比较,进一步说明对系统进行可靠极点配置的必要性·