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.     

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.     

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。     

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。     

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。     

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.      

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。     

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。     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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     

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