磁流变阻尼器的设计和磁路研究

针对人体上肢病理性震颤抑震的具体应用,结合所设计的小型旋转式磁流变阻尼器的结构特点,运用电磁学理论对磁流变阻尼器的磁路进行了设计及静态和动态特性影响因素分析,利用有限元法对磁路性质和阻尼器结构进行了仿真分析与优化,对阻尼器的电流与输出阻尼力矩关系及动态响应等性能进行了预估.提出了以质量轻和体积小为设计目的的磁流变阻尼器的磁路设计方法.     

应用于汽车发动机start/stop模式的磁流变悬置设计与分析

针对汽车在start/stop模式下发动机传递至车身的振动和扭矩过大问题,设计了一种具有惯性通道的流动模式磁流变悬置.在考虑了激励电流对磁流变液黏度的影响规律和悬置液阻效应的基础上,建立悬置的阻尼力数学模型.采用有限元软件分析了在励磁线圈作用下磁流变悬置磁路阻尼通道处的磁感应强度分布规律,分析了激励电流和磁路的结构参数对悬置恢复力和可控力的影响规律.并对磁流变悬置进行了性能测试和start/stop模式下的实车试验.结果表明,所设计的磁流变悬置具有良好的可控性,并且能有效地隔离汽车发动机在start/stop模式下的振动传递.     

基于LabVIEW的磁流变液性能测试系统的开发

磁流变液性能的测试和研究一直是可控材料研究的热点之一。鉴于目前缺乏结构简单、性能可靠测试仪器的现状,首先设计并制作了磁流变液性能测试仪,结合美国NI公司的USB-6008数据采集卡和LabVIEW软件,开发了磁流变液性能测试系统。本系统可以方便地测试出不同温度、不同磁场强度下磁流变液扭矩传递性能,易于实现不同配方的磁流变液的比较测试。     

磁流变液引信延期解除保险机构特性分析

针对准流体延期解除保险机构存在的缺陷,该文依据流体力学基本公式、磁流变液相关特性及引信环境参数,在合理假设基础上,建立了引信离心式磁流变液延期解除保险机构延期时间模型,推导出延期时间公式;利用磁导法进行了磁路设计,采用电磁场分析软件Ansoft对所设计的磁路进行数值仿真,通过仿真验证了在此磁路中磁流变液的平时安全性以及工作时泄流可靠性.通过综合分析,提出了一种使用磁流变液替代准流体的新型延期解除保险机构,该机构具有在中大口径引信中推广应用的价值.     

磁流变减振器优化的设计计算

针对磁流变减振器现存磁流变液的静置沉降、油封易磨损泄漏和磁路结构不尽合理等主要问题，提出了改进措施，对磁流变减振器中电磁场的分布进行了重新配置．以Passat B5前桥减振器为设计对象，对磁流变减振器的电磁场用有限元法进行了设计计算．实验结果表明，改进设计后磁流变减振器各项性能设计计算是令人满意的．     

磁流变风扇离合器结构设计与可控性分析

针对发动机离合器的传统驱动方式无法实现风扇转速实时连续调整,易造成发动机功率无谓损耗、冷却过度等问题,设计了一种以磁流变液为传动介质的风扇离合器。基于磁流变液Bingham模型和不可压缩粘性流体Navier-Stokes方程,建立了磁流变离合器转矩传递模型,分析了模型中各参数对输出转矩的影响。依据磁路设计理论,提出了磁流变离合器磁路的两种设计方法。采用ANSYS软件进行了磁流变离合器磁路的数值分析,验证了理论计算结果的正确性。优化设计并加工了磁流变离合器的系列试验样品。利用构建的磁流变离合器性能测试平台进行了样品的机械静态特性、输出特性、调速特性试验研究。结果显示:该磁流变离合器在2 A输入电流控制下,输出静态转矩达到13 N.m;转矩随转速差加大增加的幅度较小,保持在0.4~0.8 N.m之间;负载特性试验证实了磁流变离合器输出转速的可控性。     

基于磁流变液阻尼器的拉力器磁路分析

磁流变材料作为一种新兴的智能材料,因其具有良好的磁流变效应,而越来越受到学者的关注。根据磁流变效应设计的磁流变液阻尼器具有结构紧凑、功耗低、阻尼力大、动态范围广、响应速度快等特点,其阻尼力可通过调节外加磁场大小来控制,在工程上有广泛的应用前景。传统拉力器存在材料种类单一、拉伸倍数小、体积大、使用寿命短、重量大、难拆卸、不易携带等缺点。该文主要针对磁流变液阻尼器的磁路结构,利用MAXWELL软件进行磁路仿真。分析了活塞结构的变化对磁流变液阻尼器磁场分布的影响,为磁流变液阻尼器应用于拉力器的结构设计提供了依据。     

基于COUETTE剪切的磁流变离合器研究

介绍了磁流变液材料Bingham本构模型和工程应用性能及基于Couette剪切模式的磁流变离合器的工作原理和结构，建立了Couette剪切模式的转矩理论计算模型；对离合器设计中关键的工作磁路，利用ANSYS进行了磁场有限元仿真，提出了离合器结构的改进方法。     

筒式磁流变液联轴器的机理模型及特征解

以筒式磁流变液联轴器为研究对象,建立了考虑最大传递扭矩、转矩可调倍数、相位转差、稳定时间和设计外形尺寸等性能特征的磁流变液联轴器的非线性系统动力学模型,给出了联轴器性能指标的理论显性特征解,并基于此组特征解对MRF-132DG磁流变液联轴器的参数设计和性能评估进行实例分析.结果表明,所提出的机理模型和特征解具有更明确的物理意义,避免了数学模型繁琐的数值求解和实验性能参数拟合曲线分析过程,为类似结构磁流变液联轴器的设计和特性分析提供了更直接的指导和借鉴.     

基于磁流变阻尼器的轴系扭振特性研究

针对传统被动硅油减振器调谐范围较窄、不易匹配的问题,基于磁流变液的流变效应,提出并设计了一种应用于轴系扭振半主动控制的磁流变阻尼.根据所设计的磁流变阻尼器结构,推导建立了其力学模型,并对其进行了磁场仿真;然后将其引入到曲轴系统中,建立磁流变阻尼器-曲轴系统耦合模型,利用Newmark法进行数值仿真,获得曲轴系统的扭振响应,并分析作用于磁流变阻尼器上的电流对扭振特性的影响.结果表明:磁流变液板极外的漏磁与磁压降较小,所设计的磁路是有效的;传统的硅油减振器对曲轴6谐次扭振幅值具有较好的抑制作用,但是对4.5谐次扭振效果的抑制不理想,反而使扭振幅值增大;与传统硅油减振器相比,采用磁流变阻尼器可使曲轴系统具有明显的变刚度、变阻尼特性.通过施加合适的电流,可使曲轴系统的扭振幅值在整个工作转速范围内达到最低.      

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to