基于MFBD的汽车圆弧齿同步带动力学仿真分析研究

针对ZH型汽车圆弧齿同步带,利用CATIA软件建立汽车同步带和带轮的三维模型,通过HyperMesh软件对同步带进行网格划分,并导入多体动力学软件RecurDyn,基于MFBD刚柔耦合技术建立了汽车同步带啮合传动的动力学仿真模型,对同步带的带体和带齿上的应力进行了传动性能仿真分析,系统分析了转速和传动负载对同步带的应力分布情况的影响规律,为汽车同步带齿形设计、传动性能分析和带的橡胶及强力层等材料的选择提供了一种数字化仿真分析设计方法。     

用变节径法研究圆弧齿同步带不完全啮合区传动状态

根据圆弧齿同步带的传动特性，应用变节径法，建立了圆弧齿同步带与带轮在不完全啮合关系模型。在此基础上，分析了圆弧齿同步带与带轮的节距差、带轮齿数对啮合动干涉的影响；得出圆弧齿同步带与带轮零节距差传动有干涉，带轮具有适量的正节距差可减少啮合传动干涉，提高带的寿命。     

梯形齿与双圆弧齿同步带传动精度分析

分析了同步带齿与轮齿齿形参数在传动中产生的多边形效应基础上,建立了同步带传动精度计算模型,由此分析了紧迫长度、带与轮齿形参数对传动精度的影响,并对梯形齿、双圆弧齿同步带传动精度进行了计算和比较,为同步带在精密设备上的应用提供了计算依据。     

高齿形圆弧齿同步带轮的计算机辅助设计

本文对高齿形圆弧齿同步带在不同传动条件下进行了带轮与滚刀的计算机辅助设计。在研究滚刀加工不同齿数带轮所形成的误差分布规律及误差对带与轮啮合传动影响的基础上，确定了滚刀可加工的齿数范围与参数。为加速高齿形圆弧齿同步带的推广和应用提供了理论依据。     

双圆弧谐波传动齿廓参数对柔轮应力影响

针对设计规范中未考虑齿廓参数对柔轮疲劳寿命影响的问题,采用包络法设计无公切线双圆弧共轭齿廓,进行多体接触有限元分析,并建立齿廓参数与柔轮应力的响应面模型,分析各齿廓参数对柔轮应力的影响规律.结果表明:由于刚轮与柔轮之间的啮合齿对会约束装入波发生器时产生的柔轮变形,所以柔轮应力对齿廓参数变化的敏感度较高;谐波传动为多齿啮合传动,单个接触齿对受载较小,载荷对柔轮应力影响较小;齿厚比和双圆弧倾角对柔轮应力的影响最大,齿顶高系数和齿根圆角半径的影响次之,齿根高系数的影响最小;柔轮应力随齿根半径和齿根高系数的增大先减小后增大,其余齿形参数与柔轮应力呈负相关.     

基于MATLAB双顶置同步带正时传动系统参数计算机仿真分析

基于汽车发动机正时同步带多轮传动系统布局设计理论体系,提出了双顶置同步带传动系统计算机辅助设计方案。根据多轮传动系统构成特点,建立了传动系统计算模型,利用MATLAB进行了双顶置同步带传动系统分析软件开发,实现了传动系统参数设计与计算过程程序化,并对张紧力作用下的系统啮合干涉形貌进行了计算。通过对469Q汽油机正时传动系统实例的仿真计算,验证了软件的可行性。     

新型平顶圆弧齿同步带带齿变形的研究

本文利用平面弹性理论的保角映射函数法，提出了圆弧齿同步带带齿变形的计算方法。利用这种方法，以接触压力为基础计算出了带齿变形、接触变形及齿廊上各点刚度分布，并根据带齿等接触强度原则，讨论了带轮齿廊修形方法。     

谐波减速器柔轮冷滚工艺及残余应力数值模拟

针对柔轮工作性能的特殊要求,分析并优化了传统柔轮冷滚压工艺模型,柔轮采用双圆弧齿廓曲线模型;依据修正的Johnson-Cook本构模型建立柔轮冷滚压成形有限元模型并加以验证。仿真结果表明,采用该模型能得到清晰的双圆弧齿形和较均匀的等效应变分布。文中还分析了不同工艺参数(进给速度、滚轮转速及摩擦系数)对柔轮轮齿表面残余应力的影响,结果表明:增大进给速度会降低轮齿表面的残余应力最大值,过大的进给速度会造成"凸起";适当降低滚轮转速和进给速度,可提高残余应力分布的均匀性;摩擦系数与残余压应力分布深度正相关.     

HTD齿形同步带啮合受力分析

HTD同步带经过多次变异,目前已经成为传动性能最好的同步带齿形之一。基于同步带啮合原理,采用复变函数方法分析带齿应力分布与齿形参数之间的关系,运用有限元基本理论分析带齿与轮齿接触受力特征,为研究该齿形同步带传动受力特性和开发国产新同步带齿形提供理论依据。     

同步带变形纱包覆布简介

同步带是以钢丝、玻璃纤维以及合成纤维线等为强力层,用聚氨酯或氯丁橡胶代替天然橡胶与丁苯橡胶作为浇注胶基体,经模具压制、粘合成带状圆圈,且在带的内周压制成齿状。这种齿状带的齿与带轮的齿相啮合便可传递动力。同步带是一种新型传动带,因为它是利用带齿和带齿轮相啮合传递动力,故其兼有齿轮传动、链传动和皮带传动的优点,并克服了其它各种传动带伸长及打滑的缺点,能使     

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