齿轮参数的实测

本文主要叙述对齿轮,齿顶圆直径,斜齿螺旋角,模数及修正齿轮的识别方法,有助于现场工作的同志,作为参考。 1 测量齿顶圆直径由于齿顶圆不易磨损,并且易于测绘,常测已齿轮外径作为计算其它齿轮参数的依据。当齿轮齿为偶数时,可直接量出。     

齿顶圆误差对上置式齿形仪测量精度的影响

在采用以齿顶圆定位的直角座标法测量原理测量渐开线齿形时,被测齿轮的齿顶圆误差将会产生较大的测量误差。本文阐述了仪器测量时座标系的建立方法以及被测齿轮齿顶圆误差对测量精度影响的分析。     

降低齿轮噪声的工艺措施

齿面的制造质量,将直接影响齿轮的工作状况及传动的平稳性与工作噪声,通过对齿轮加工工艺措施的改进,取得了明显的降噪效果. 1 改变齿面形状 1.1 齿顶啮合修缘 齿顶啮合修缘工艺方法,是将齿轮齿顶修成一个过渡线,这样就可以控制齿轮副在传动过程中的平稳性.修缘部分可以是一条直线或一条均匀上凸曲线.通常,修形尺寸为高度尺寸修整量0.45×m,宽度尺寸修整量(0.001～0.008)×m.     

日本渐开线行星齿轮减速机的测绘与剖析

根据对日本渐开线行星齿轮减速机的测绘结果,分析、计算了插齿加工中插齿刀的变位系数对行星齿轮传动,特别是内啮合副中的“过渡曲线干涉”的影响,以及对被切齿轮齿顶圆直径的影响。结果表明,在渐开线行星齿轮传动中采用标准齿轮传动时,只要适当控制插齿刀的变位系数,即使不减小内齿轮的齿高,也不会发生内齿轮齿顶与行星轮齿根的“过渡曲线干涉”;插齿刀的变位系数对被切齿轮的齿顶圆直径影响也不大。     

非圆齿轮齿廓数值计算的研究

提出了一种简单准确的非圆齿轮齿廓的数值算法．该方法从齿廓形成原理和过程出发，将非圆齿轮齿廓的计算转化成了求非圆齿轮节曲线的法向等距线和插齿刀齿廓的交点过程，因此只需要给出非圆齿轮节曲线、插齿刀参数和插齿数据，就可以非常迅速准确地计算出非圆齿轮，其中包括齿顶、工作齿廓、过渡曲线和齿根曲线的全部齿廓数据．同时，它还可以检查非圆齿轮是否发生根切或齿顶变尖等设计缺陷，为非圆齿轮的测量和线切割加工提供了准确的齿廓曲线数据．目前，该方法已经成功地应用于非圆齿轮齿廓线切割的加工中，并取得了良好的效益．     

渐开线直齿圆柱齿轮参数的测量与计算

本文阐述了渐开线直齿圆柱齿轮齿顶圆直径的测量与齿轮模数、变位系数、压力角等参数的确定方法和步骤.     

微齿轮齿面磨损行为及仿真分析

微型齿轮作为微机电系统(MEMS)的关键零部件,齿面磨损是影响其服役性能及失效形式的主要因素之一。为了研究微齿轮齿面磨损机理,基于Archard磨损理论,利用ABAQUS二次开发UMESHMOTION子程序,结合ALE自适应网格技术,建立了微齿轮齿面磨损有限元分析模型,得到了不同啮合周期下的齿面磨损分布规律,并进行了试验验证。基于构建的有限元模型,考虑主、从齿面磨损的相互作用,分析了不同材料性能(弹性模量)及材料配对方式对齿面磨损分布及大小的影响。研究结果表明,微齿轮齿面磨损最严重的地方发生在靠近齿根的基圆附近,齿顶附近磨损较轻;与材料性能相比,不同材料配对对微齿轮磨损大小影响更显著。     

Fe_(78)Si_9B_(13)非晶磁粉芯工艺

研究了粉末制备方法、粉末粒度、绝缘剂添加量等因素对Fe78Si9B13非晶磁粉芯性能的影响.结果表明,气流磨法得到的粉末比机械法得到的粉末棱角少,多数粉末呈圆片状,利于绝缘包覆,因此,其粉芯磁性能比后者高;粉末粒度越大磁粉芯磁导率越高,但是损耗也越大,所以需要粒级调配,最终确定最佳配比为75~100μm占70%,61~75μm占10%,45~61μm占20%.添加绝缘剂可提高粉末的固有电阻,降低涡流损耗.但绝缘剂含量过大时会降低粉芯的磁导率,本实验确定最佳添加量为4%.     

销齿传动的重合度计算法

指出现有机械设计手册中销齿传动的重合度求法存在的问题,推导出重合度理论计算公式,同时确定了齿轮齿顶圆半径的取值范围     

基于圆弧啮合线内啮合齿轮设计与特性分析

针对内啮合齿轮传动,提出1种基于圆弧啮合线的大重合度内啮合齿轮构造方法。选取连接外齿轮和内齿圈节圆交点和齿顶圆交点的圆弧为啮合线,构造在该啮合线上共轭的外齿轮和内齿圈齿顶齿廓;根据共轭原理设计与齿顶齿廓共轭的齿根齿廓,完成内齿圈齿根齿廓修形;对新齿形进行根切检验,分析新齿形啮合几何特性及加载接触;利用数控加工方法完成内啮合齿轮样件的加工并进行啮合试验。研究结果表明:新齿形不产生根切和齿顶干涉;与渐开线内啮合齿轮相比,新齿形重合度大大提高,相对滑动率减小,相对法曲率增大;齿面接触和齿根弯曲应力显著降低,承载能力大大提高;齿数比为38/53的新齿形存在7对齿接触,验证了新齿形的大重合度啮合。     

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