滚子包络环面蜗杆传动副装配误差分析

为了掌握装配误差对滚子包络环面蜗杆传动副齿面接触的影响规律,基于齿轮啮合原理和微分几何原理,在滚子包络环面蜗杆传动副的理论啮合几何学模型的基础上,建立了考虑中心距误差、蜗杆轴向误差、蜗轮轴向误差和轴交角误差等4项装配误差的传动副干涉分析模型,提出了传动副在2种干涉情况下的定量评价指标及其数值计算方法,通过实例计算验证了数学模型的正确性.实例分析结果表明:滚子包络环面蜗杆传动副的理论接触线为中间平面附近的一条空间圆柱螺旋曲线;在装配误差的各分量中,蜗杆轴向误差对接触干涉情况影响最大,蜗轮轴向误差影响最小.     

蜗杆传动模糊可靠性优化设计

阐述了模糊可靠性设计的本质和特点；结合实例建立了ZK蜗杆传动多目标模糊可靠性优化设计的数学模型，给出了优化方法及优化参数。     

滚子包络端面啮合蜗杆传动的啮合性能分析

为了提高蜗杆的承载能力、传动精度和效率,提出一种新型蜗杆传动形式——滚子包络端面啮合蜗杆传动。根据微分几何和齿轮啮合原理建立坐标系,推导蜗杆齿面方程,以及诱导法曲率、润滑角、卷吸速度和自转角等齿面啮合参数计算公式,研究蜗杆主要设计参数对啮合性能的影响规律。研究结果表明:滚子包络端面啮合蜗杆传动的单段蜗杆与蜗轮同时啮合齿对数为5,具有较高的承载能力;最大润滑角达到89°以上,具有良好的润滑性能,为后续的优化设计确定了参数合理的取值范围。     

蜗杆传动的可靠性设计

本文应用摄动法和可靠性设计理论,讨论了蜗杆传动中的可靠性设计问题,在基本随机参数的概率特性已知的情况下,对蜗杆传动进行可靠性设计,并且编制了实用的计算机程序,可以迅速准确地得到蜗杆传动的可靠性设计信息。     

加工和安装误差对无侧隙蜗杆传动接触线及齿廓的影响

在具有加工和安装误差的情况下,为了研究各蜗杆参数对无侧隙双滚子包络环面蜗杆的齿廓及蜗杆齿面接触线的影响规律,建立了包含加工误差和安装误差的蜗杆传动啮合函数,建立了蜗杆齿面接触线及蜗杆齿廓方程,利用三维建模技术分析了蜗杆、蜗轮轴交角误差,中心距误差,蜗杆轴向窜动误差,蜗轮滚子齿距角误差,砂轮滚子偏距误差,转角误差等对蜗杆齿廓的影响,同时分析了在误差作用下蜗杆齿面接触线发生的变化,并进行了运动学仿真.研究结果表明:转角误差、砂轮滚子齿距角误差达0.5°时对蜗杆齿廓影响较为明显,即容易产生卡死现象;当蜗杆轴交角误差达0.5°时,整个蜗杆齿廓产生了严重变形,且蜗杆轴断面变为椭圆形,极易发生蜗轮轮齿折断现象;其他误差在1 mm以内时对齿廓及齿接触线的影响较小.     

砂轮半径对锥面二次包络圆柱蜗杆啮合性能的影响

介绍了一种新型蜗杆传动—锥面二次包络圆柱蜗杆,根据一二包络过程的运动关系推导了啮合方程和蜗杆与蜗轮的齿面方程,通过大量编程计算得到了啮合性能指标与原始参数之间的关系,并以图表直观地表示出在砂轮的不同半径下的啮合特性,为这类蜗杆传动中蜗轮滚刀的设计制造提供了理论参考。     

倾斜式双滚子包络环面蜗杆传动几何特性分析

为消除环面蜗杆传动齿侧间隙,提出倾斜式双滚子包络环面蜗杆传动,采取双排滚子错位布置,且滚子轴线与蜗轮径向倾斜一定角度. 阐述了倾斜式双滚子包络环面蜗杆传动的工作原理,依据空间齿轮啮合理论和微分几何理论,采用运动学法建立了蜗杆副的静态坐标系及活动坐标系,推导了该新型环面蜗杆齿面方程,并导出了该传动的蜗杆轴向截面齿廓方程、法向截面齿廓方程、一界函数、螺旋升角等几何特性相关的方程及计算公式,分析了滚柱半径R、滚柱偏距c₂、倾斜角γ等啮合参数对蜗杆几何特性的影响. 结果表明:该新型传动蜗杆喉部齿廓非常接近直线,蜗杆不会发生根切和齿顶变尖现象. 要使该传动保持良好的几何特性,R不宜超过12 mm,c₂在5~9 mm之间,γ在18°~25°之间.      

柱面包络环面蜗杆齿面数控加工的计算机仿真

在建立柱面包络环面蜗杆传动数学模型的基础上，运用三维计算图形技术，编制绘出环面蜗杆齿面正等轴测图的计算机程序，在计算机上实现了蜗杆齿面的计算机仿真，并对柱面包络环面蜗杆齿面及修形后的蜗杆齿面进行计算机仿真，为数控机床加工蜗杆提供了理论参考。     

模糊可靠性优化设计及其在蜗杆传动中的应用

在普通优化设计的基础上，依据模糊数学和统计学的原理，探讨了模糊可靠性优化设计的方法，并针对圆柱蜗杆传动，建立了模糊可靠性优化的数学模型，进行了实例计算分析。     

锥蜗杆传动的合理布置及双蜗轮传动的分析研究

本文对锥蜗杆传动布置方式进行了研究,确定了锥蜗杆传动唯一可行的合理布置基本型,同时对锥蜗杆驱动两个安装在同一回转轴上的锥蜗轮布置方式的啮合状态和啮合性能进行了研究,确定了这种传动方式的可行性和最佳相对运动方式。     

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…     

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。     

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     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

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.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.