复合摆线少齿差行星传动的啮合性能分析

采用几何特性可调性强的复合摆线作为内齿廓,根据微分几何和齿轮啮合原理,按照少齿差运动规律,建立啮合方程以及共轭齿廓方程,并推导了齿轮副的啮合线、重合度、啮合界限、根切条件.分析了齿轮副诱导法曲率、压力角以及齿形调节系数对齿轮压力角的影响,设计并建立了齿轮副三维实体模型,进行了动力学仿真,模拟一定工况下齿轮副运动关系及传递效率.结果表明,复合摆线少齿差行星传动具有多齿啮合、传动压力角小、齿轮副诱导法曲率小、传动效率高等优良的啮合性能.     

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。     

平面内齿轮包络凸环面蜗杆传动啮合性能分析

提出一种新型蜗杆传动形式——平面内齿轮包络凸环面蜗杆传动。以微分几何和空间啮合理论为基础建立该传动的啮合函数、齿面方程的数学模型。分析该传动的各种传动形式,研究其母平面倾角对啮合性能的影响规律。研究结果表明:母平面倾角决定传动副的接触线分布;平面内齿轮一次包络凸环面蜗杆传动具有良好的润滑性能;平面内齿轮二次包络凸环面蜗杆传动具有较高的承载能力。为研制承载能力高、润滑性能好、体积小的新型动力蜗杆传动形式提供理论基础。     

新型变曲率椭圆内齿型少齿差行星齿轮副的啮合特性与传动性能

根据摆线针轮少齿差行星传动原理,把圆形针齿齿廓看作两焦点重合的特殊定曲率椭圆曲线,在此基础上提出了一种新型高性能变曲率椭圆内齿型少齿差行星齿轮副:引入轴长系数λ分析了变曲率椭圆齿廓曲线的几何原理;基于微分几何和齿轮啮合原理,建立了新型变曲率椭圆内齿齿廓方程,并推导了与其共轭的少齿差行星齿廓方程;分析了该新型齿轮副的啮合线、根切条件、啮合界限、压力角、诱导法曲率和滑动率等啮合特性。研究表明:新型齿轮副具有多齿啮合特性;根切界限方程和啮合界限模型分别为共轭齿廓的根切判定、椭圆内齿的齿根优化提供了有效的理论设计方法;相对于摆线行星传动,当齿高确定时,减小轴长系数λ可降低齿轮副压力角、诱导法曲率以及滑动率敏感区间的滑动率幅值和平均值。应用该新型齿轮副对发动机可变气门正时系统的减速装置进行了机构设计与传动性能仿真分析,结果表明:相对于同类型的摆线行星传动,新型齿轮副在传动效率与传动精度方面具有优势。最后加工出了减速装置的物理样机,并测试了样机的回差。测得的回差能很好地满足设计要求,表明回差仿真模型与仿真结果具有合理性。     

直线共轭内啮合齿轮副的重合度研究

根据齿轮啮合原理,参照渐开线齿轮定义了直线齿廓外齿轮的基本参数,得出了齿形半角、压力角和最小齿数的关系,得到直线齿形齿轮的齿廓方程,在此基础上对啮合极限点进行了研究。为满足连续传动的要求,推导出直线共轭内啮合齿轮副啮合曲线,并分析了直线共轭内啮合齿轮传动的啮合特性。根据重合度计算理论推导出直线共轭内啮合齿轮副重合度的计算公式,保证在齿形参数设计时满足连续传动的要求。根据齿轮的基本参数和重合度的计算公式,研究外齿轮齿顶高系数、内齿圈齿顶高系数、压力角与重合度的关系。     

大模数内齿轮滚刀的齿形分析

对大模数内齿轮球形滚刀的一种齿形进行啮合理论分析,求出滚刀加工出来内齿轮的齿形,然后与标准内齿轮的齿形比较,结果表明：该齿形的滚刀加工的内齿轮能满足要求。     

新型复合摆线外啮合圆柱齿轮副的传动特性分析

基于传统摆线成形原理,提出了摆线成形的二连杆等效机构转化方法,得到了n+1连杆机构生成广义n阶摆线轨迹的运动规律,推导并建立了可用于齿轮传动的新型四阶复合摆线齿廓方程;基于微分几何及共轭啮合理论,推导了复合摆线齿廓的共轭齿廓方程,分析了该新型齿轮副的压力角、曲率、重合度、滑动率等啮合特性;进行了齿轮副三维实体模型的精确构建,并利用有限元法分析了该齿轮副的强度特性。研究表明:当齿高确定时,分度圆压力角由齿形调控系数f1控制;齿廓曲线是由凹凸弧组成的光滑曲线,且传动过程始终为凹凸齿面线接触啮合传动,理论上具有较高的接触疲劳强度;相对于渐开线齿轮,复合摆线齿轮副具有较高的重合度、极小的滑动率以及较高的弯曲强度和接触强度。最后,加工了齿轮副试验样件,并在FZG齿轮试验机上测试了不同工况下的传动效率,结果表明:复合摆线齿轮副的传动效率随加载扭矩在97.30%~99.00%范围内呈正相关变化,且高于同工况下的渐开线齿轮副,具有工程应用价值。     

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。     

准双曲面齿轮啮合原理及其在刀倾半展成加工中的应用

研究准双曲面齿轮的啮合原理是制订它的加工方法的基础。本文根据“二阶曲面展成”的理论分析了准双曲面齿轮传动的一些重要问题,主要是共轭齿面的诱导法曲率及接触线方向角,同时分析了在刀倾半展成法加工准双曲面齿轮副时运用这些原理确定原始产形轮及实用产形轮参数的方法.     

点接触曲线构型内啮合齿轮传动接触特性分析

内啮合齿轮传动具有结构紧凑、体积小、承载能力高等特点,在行星齿轮传动机构中获得广泛应用。为进一步提高内啮合齿轮副传动性能,在齿轮共轭曲线理论的研究基础上,本文提出一种点接触曲线构型内啮合齿轮传动形式,建立点接触曲线构型内啮合齿轮传动基本数学模型,通过空间共轭曲线副实现较灵活的齿面设计,满足高性能使用需求。分析点接触曲线构型内啮合齿轮副接触特性,建立齿面运动分析模型,探讨连续旋转运动下齿面实际啮合特征;提出适用于该内啮合齿轮副的齿面重合度分析计算方法,推导依据空间共轭曲线副评判成型齿面滑动率的一般计算公式,讨论不同参数影响下齿面滑动率变化规律;概述点接触曲线构型内啮合齿轮副齿面法曲率计算原则,提出齿面干涉分析依据等。相关研究为后续构建高性能齿轮传动副奠定理论基础和技术支撑,具有重要的理论意义和工程应用价值。     

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.     

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.     

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-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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