一种进口采煤机链轨的研究

采煤机在运行中是沿牵引轨道行走的，链轨的受力状态与强度，对其使用寿命起决定性影响。本文着重对引进采煤机无链牵引机构的链轨截面轮廓进行分析，并对其受力进行较深入的研究。     

双滚筒采煤机动力学分析及力学模型建立

为保证采煤机安全可靠的工作,满足其机械动态特性和低振动要求,以双滚筒采煤机整机为研究对象,对其受力进行分析。依据采煤机的实际情况和工作状态,假设:采煤机无故障运行;各部分的质量分布均匀且为刚体;并且通过无质量的弹性元件连接,阻尼为粘性阻尼。在此基础上,建立了双滚筒采煤机整机的力学模型。此模型为数学模型的建立奠定了基础,为进一步对采煤机进行动态分析创造了条件。     

采煤机整机力学模型的最小二乘解算方法

为探寻双滚筒式采煤机在不同工况下各滑靴受力的变化规律,分析整机受力状态与数学模型结构的关系,改善采煤机整机受力状态,建立了采煤机整机受力的数学模型,并预先给出模型状态判断,基于最小二乘原理和广义逆,利用matlab编制计算程序,解算出不同工况下各滑靴受力的最佳逼近值,得到了煤层倾角和仰(俯)角变化对滑靴受力变化的影响曲线.结果表明:所建模型可以反映生产实际中各滑靴受力情况,利用最小二乘原理解算采煤机不相容奇异力学模型的方法有效,得到了外负载与各滑靴受力的平衡变化规律.     

采煤机整机力学模型的最小二乘解算方法

为探寻双滚筒式采煤机在不同工况下各滑靴受力的变化规律,分析整机受力状态与数学模型结构的关系,改善采煤机整机受力状态,建立采煤机整机受力的数学模型,并预先给出模型状态判断,基于最小二乘原理和广义逆,利用matlab编制计算程序,解算出不同工况下各滑靴受力的最佳逼近值,得到了煤层倾角和仰(俯)角变化对滑靴受力变化的影响曲线.结果表明:所建模型可以反映生产实际中各滑靴受力情况,利用最小二乘原理解算采煤机不相容奇异力学模型的方法有效,得到外负载与各滑靴受力的平衡变化规律.     

液压驱动滚动并联机构运动可行性与仿真分析

提出一种新型三自由度液压驱动滚动并联机构。各条支链采用液压缸驱动的反平行四边形机构,通过支链的伸缩比放大作用实现并联机构整体的大变形,并利用液压系统响应快速、输出力强的特点,保证并联机构的移动灵活性与大负载能力。描述该并联机构的组成、特定条件下的奇异位型以及1个翻滚步态周期的5种地面支撑状态与给定机构参数下液压杆伸缩的可行域。对并联机构在5种地面支撑状态的运动可行性与可行域以及基于ADAMSTM对翻滚过程的动力学仿真进行分析。研究结果表明:该机构实现了翻滚运动,同时得到了运动过程中液压缸的位移、伸缩速度与受力数据,可为实验样机设计与构型优化提供参考。     

双滚筒式采煤机整机力学模型与解算方法

为了探究滚筒采煤机整机的受力规律,在综合考虑煤机结构布置、动力参数和煤层倾角等条件的基础上,建立满足动力参数相匹配条件和牵引力平衡约束条件的采煤机整机力学模型,分析整机受力状态对力学模型的线性方程组系数矩阵秩的影响,给出具有针对性的预先估算、状态判断等综合的解算方法。结果表明:滑靴受力的理论分析与生产实际吻合,可以准确地反映动力参数匹配和各支反力的变化规律,说明分析和解算方法是正确的。该研究为采煤机设计计算与力学分析提供了理论方法和依据。     

MLS_3——170型采煤机牵引部液压伺服机构的稳定性分析

MLS_3——170型采煤机液压牵引部的主油路是一个典型的变量泵一定量马达的闭式系统。改变斜轴式变量泵的摆角,就可以调整机器的牵引速度。 MLS_3——170型采煤机上变量泵缸体的摆角是由一套专门的液压伺服机构来控制的。机器牵引速度的手动操纵和各种自动控制环节均通过伺服机构对油泵的摆角进行调节。为此,液压伺眼机构在该机器里的作用是对各种调速信号进行功率放大,控制油泵的摆角并检测误差。所以,该液压伺服机构的性能对整机的动特性有很大的影响。在对EDW——170L型和MLS_2——170型采煤机牵引部液压伺服机构的实验室研究     

液压缓冲滑车碰撞试验力学建模及数值分析

以液压缓冲滑车碰撞试验装置为研究对象,应用有关力学和流体力学理论,对碰撞过程中滑车和液压缸活塞的受力、运动以及液压缸的压力变化进行了分析。根据能量守恒原理,构建了滑车碰撞过程的力学模型和能量守恒模型,采用离散求解方法,对所建立的模型实现了数值求解。针对某一具体算例,深入研究了滑车质量、初始碰撞速度、阻尼孔直径等参数对碰撞过程的性能影响,得到了一系列规律性的曲线。结果表明:滑车的加速度随初始碰撞速度、阻尼孔长度增大而增大,随滑车质量、阻尼孔间距的增大而减小;碰撞过程中,滑车质量越大,滑车速度降低得越慢;阻尼孔长度越大、阻尼孔直径越小,速度变化得越快;滑车位移随滑车质量、初始碰撞速度、阻尼孔间距、阻尼孔直径的增大而增大,随阻尼孔长度的增大而减小。     

运动参数对采煤机滚筒载荷影响的模拟研究

为探究牵引速度和滚筒转速对采煤机滚筒载荷的影响,通过建立采煤机滚筒三向载荷均值与波动系数的数学模型,基于Matlab/GUI软件平台,利用设计的滚筒载荷模拟系统,以国产某型采煤机为例,得出其滚筒载荷均值与波动系数随牵引速度、滚筒转速变化的曲线,发现了载荷均值与波动系数随运动参数变化的规律,分析了运动参数对滚筒载荷的影响,为合理确定采煤机运动参数提供依据.     

采煤机运动参数对工作面温升的影响

采煤工作面的温度关系到工人的健康、设备的使用性能和煤炭生产的安全。为了研究采煤机运动参数对工作面温升的影响,建立了采煤机设计参数与工作面温升关系的数学模型,分析了采煤机的牵引速度、滚筒转速与工作面温升之间的关系及其影响。模拟结果表明,采煤机的运动参数对工作面的温升有直接的影响,工作面的温度随采煤机牵引速度的提高迅速增加,滚筒转速对工作面的温升影响较大;适当降低采煤机的牵引速度和滚筒转速能降低采煤工作面的温升。该结果为正确选择采煤机的运动参数、减少采煤机工作发热、降低采煤工作面温升、进一步改善采煤工作面的环境提供了依据。     

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.     

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     

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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