考虑制造误差的人字齿行星传动均载特性

以人字齿行星齿轮传动系统为研究对象,基于齿轮系统动力学理论和牛顿运动定律,考虑各构件制造偏心误差和齿廓误差、时变啮合刚度、轴承支承刚度以及陀螺效应等因素,运用集中参数法建立考虑人字齿轮实际结构特点的该型传动弯-扭-轴耦合动力学模型;通过计算在不同浮动方式下的系统均载系数,获得太阳轮偏心误差以及齿廓误差与系统均载系数关系曲线,进而分析在不同浮动方式下制造误差对人字齿行星传动均载特性的影响;同时对比分析在有太阳轮浮动和非浮动情况下,太阳轮的径向浮动能力。研究结果表明:制造误差和构件浮动对人字齿行星传动均载性能有显著的影响,构件浮动可以明显地改善系统均载特性,并且系统均载系数随制造误差的增加而增大;与非浮动情况相比,浮动太阳轮时太阳轮中心径向位移量明显较大,提高了太阳轮浮动能力。     

含有浮动组合内齿圈的人字齿行星齿轮系统静态均载特性

基于集中参数法,建立含有浮动组合内齿圈的人字齿行星齿轮传动系统静态均载计算模型,并针对其进行静态均载特性行为的理论研究。考虑时变啮合刚度、各构件偏心误差激励、中心构件浮动等影响因素,并利用傅立叶级数法求解系统载荷平衡方程,定性地分析各构件偏心误差、中心构件浮动方式及浮动量、柔性内齿圈扭转刚度等参数对系统静态均载特性行为的影响。研究结果表明:系统均载系数随着偏心误差的增大而增大,构件偏心误差共同作用对均载系数的影响比构件偏心误差单独作用时的影响大;柔性内齿圈扭转刚度的改变对太阳轮、内齿圈的浮动量及系统的均载系数均有影响;含有浮动组合内齿圈的人字齿行星齿轮系统较一般人字齿行星齿轮系统有更好的均载效果。     

考虑齿圈柔性的行星传动系统固有特性与灵敏度研究

为有效地模拟行星齿轮传动系统齿圈结构柔性,采用有限元方法建立了齿圈结构模型,依据啮合力与内齿圈的变形协调关系建立了传动系统刚-柔耦合动力学模型,求解了系统固有频率与振型,阐述了耦合系统固有频率的分布规律,依据系统振动特征,将系统振型划分为6种振动模式。计算了系统刚度对各阶固有频率的灵敏度,可作为行星传动系统振动抑制的依据,分析了系统扭转振动随太阳轮扭转刚度和太阳轮与行星轮啮合刚度的变化规律,讨论了齿圈厚度对系统固有频率分布、子系统耦合阶次与振动模式的影响,发现系统固有频率均会在齿轮子系统扭转振动频率位置出现,但随着齿圈厚度的增加,与之耦合的齿圈振动模式则逐渐由高阶节径振动逐渐降低,系统一阶振型也会由齿圈节径振动模式转变为齿圈刚体振动模式。     

双排行星齿轮系统的静态均载特性行为

建立双排行星齿轮传动系统的计算模型,并针对其进行静态均载特性行为的理论研究。模型中考虑各级行星齿轮的偏心误差,静态传递误差,时变啮合刚度等参数,并利用傅里叶级数法求解系统载荷平衡方程。定性地研究行星轮的偏心误差,齿圈的支撑刚度,行星轮的支撑刚度以及一级行星架的扭转刚度等参数对系统静态均载特性行为的影响,并据此得到一些理论分析结果。该研究延伸和扩展了对双排行星轮系均载特性行为的认识,并为进一步进行动力学均载行为的理论和实验研究形成一定的基础,同时也为双排行星轮系的设计提供一定的参考。     

基于啮合特性的人字齿轮动力学建模与分析

利用人字齿轮啮合特性的分析结果,准确计算人字齿轮轮齿时变啮合刚度激励和误差激励。根据齿轮啮合冲击模型,计算人字齿轮啮入冲击激励。根据人字齿轮的均载传动特性,综合考虑上述3种激励,利用集中参数理论建立人字齿轮12自由度弯曲—扭转—轴向变形耦合的三维空间动力学模型。应用牛顿第二定律,建立系统的振动方程,对方程进行消除刚体位移和量纲归一化处理。采用变步长四阶龙格库塔法(Runge-Kutta)求解,得到系统的振动响应和动态特性。结果表明:人字齿轮动力学模型的建立、求解和分析为其动态设计奠定了基础。     

新型自减振行星传动系统动态特性分析

为了改善内、外部激励下机电传动系统的动态响应特性,提出一种新型自减振行星传动形式:TVD-PG(torsional vibration damper and planetary gear)传动系统,采用扭转减振装置取代传统行星齿轮中某一构件与箱体固连的方式.考虑传动轴扭转变形和行星齿轮时变啮合刚度,建立电机和适用于变速工况下的TVD-PG传动系统的耦合动力学模型.仿真分析了TVD-PG传动系统在启动和稳定工况时的动态响应特性,并与传统的行星齿轮传动方式进行对比.结果表明:在启动阶段,TVD-PG传动系统可快速减小电机电磁转矩波动,使电机和输出端转速快速平稳上升,同时改善了启动和稳定工况下行星齿轮系统的动态啮合力状况.由于机电耦合作用,在系统稳定时可清晰观察到齿轮系统内部激励参数对电机部分的影响.     

行星传动均载及动载系数定义改进与分析

针对目前对于行星传动中的均载与动载的定义存在差异并与ISO齿轮标准不相符的问题,对行星传动系统均载和动载特性进行了分析并给出了更加准确的定义。该定义修正了现有文献对瞬时动载系数中的静载荷定义理解的误区,并对均载系数定义中未能包含系统所有因素的影响(缺失齿轮振动影响)以及动载系数定义并非仅含齿轮振动影响予以纠正。此外,建立了考虑时变啮合刚度、陀螺效应及综合误差的行星传动系统平移扭转耦合动力学方程,同时对系统行星轮存在偏心误差和位置误差下改进前后瞬时均载系数和瞬时动载系数进行了对比,更加准确地获得了系统特性变化状况,突出了改进后的优点,为行星传动系统的减振和降噪提供了参考。     

太阳轮偏心误差对人字齿行星传动动态特性影响

以人字齿行星齿轮为研究对象,考虑人字齿轮实际结构,基于集中参数理论,建立计入各个构件轴向振动的人字齿轮行星传动广义动力学模型,建模中考虑制造偏心误差和齿廓误差、轴承支撑刚度、轮齿时变啮合刚度和陀螺效应等影响因素.该模型可用于具有不同类型制造误差和任意数目行星轮的人字齿行星传动振动性能分析.采用数值算法求解系统受迫振动响应,分别分析了时域和频域动态响应.以太阳轮制造偏心误差Es为例,着重研究Es对人字齿行星传动动态特性影响规律.结果表明:制造误差Es增强了人字齿行星传动系统中的动态响应以及动态啮合力的波动.     

基于分流均衡要求的行星传动基本构件浮动量分析

根据从动力学角度建立的行星传动系统计算模型,考虑系统的误差、工况条件、构件的支承刚度对基本构件浮动量的影响,推导行星传动的动力学方程;计算在载荷分流均衡要求下基本构件的浮动量;分析系统主要设计参数对浮动量的影响,为行星齿轮传动系统的均载结构设计提供依据.研究结果表明系统的浮动量随着对载荷均衡要求、转速、系统行星轮个数、基本构件支承刚度和系统构件误差的增加而增大,各构件的误差对系统浮动量的影响有累加作用;系统的误差、工况条件、构件的尺寸参数和支承刚度等因素均影响系统的浮动量,在实际分析中要予以考虑.     

一般性直齿面齿轮双分支传动系统静态均载特性

为系统研究面齿轮分支传动系统的静态均载特性,分析了非正交偏置的一般性直齿面齿轮双分支布置形式、系统啮合相位差,考虑安装误差和弹性变形推导了系统的变形协调条件,并与扭矩平衡条件和静力平衡条件联立,建立了非正交偏置的一般性直齿面齿轮双分支传动系统的静力学扭矩分配模型,给出了静态均载系数的计算方法,分析了安装误差、输入载荷、支撑刚度、扭转刚度及啮合刚度波动幅值对静态均载特性的影响.结果表明:分流级轴错角误差对均载性能影响最大,且当存在安装误差时,输入载荷和扭转刚度对均载性能有重要影响;为获得系统的均载,应消除啮合相位差影响,并采用偏置分流传动形式,同时减小输入小轮支撑刚度及各齿轮副啮合刚度波动幅值.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

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.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

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

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-