吊头激励下的柔索摆系统建模与仿真

根据起重船柔索摆系统的运动特性,将其运动分解成相互独立的吊物摆动分量和吊索波动分量;采用弦振动理论构建了混合初始边界条件下确保存在唯一性的吊索波动数学模型,并利用无条件稳定的隐式差分法解决了其数值解的稳定性问题;采用以球坐标为摆动角的吊物摆动数学模型和叠加原理得到了逼真的柔索摆运动形态.仿真结果表明,所提出的数学模型和算法能够求解出逼真的柔索摆实时运动形态.     

采煤机截煤时动力学行为的研究

1 采煤机截煤时的运动微分方程及其求解由Lagrange方程推得采煤机截煤时运动微分方程为一普通的二阶常微分方程组:F_i(X_k,y_k,γ_1,γ_2,φ_1,_2,φ_c,φ_u,θ_d,X_k,y_k,γ_1,γ_2,φ_1,φ_2,φ_c,φ_u,θ_d,X_k,y_k,γ_1,γ_2,φ_1,φ_2,φ_c,φ_b,θ_d)=0(i=1,2,…,9)式中广义坐标X_k、y_k——采煤机机体(除摇臂、螺旋滚筒外)的重心的b、a轴方向位移;γ_1、γ_2——前后摇臂相对于采煤机机体的摆角;φ_1、φ_2——前后滚筒相对于采煤机机体的转角;θ_c——电动机转于相对于采煤机机体的转角;φ_c、φ_b——采煤机机体绕C轴、b轴的转角。     

少齿差偏摆齿轮传动机构平衡的探讨

少齿差偏摆锥齿轮传动有传动比大、结构紧凑、重量轻、承载力大等优点,但存在着离心惯性力和轴向惯性力,因而引起多方向的振动。本文通过对运动的分析探讨解决此类机构平衡问题的方法。     

基于Matlab软件的双杆摆系统混沌研究

建立了双杆摆的欧拉-拉格朗日运动方程,利用Matlab软件对欧拉-拉格朗日运动方程进行数值计算,给出摆球的轨迹及其相图。研究结果表明：双杆摆系统有着丰富的混沌现象。     

球笼式等速万向节圆周间隙分析

针对球笼式等速万向节的结构与运动形式，建立了椭圆沟道截面圆周间隙的空间立体模型，推导了圆周间隙角θ在任意摆角和转角条件下的计算公式，使用Matlab软件研究了θ随摆角和转角变化的规律.结果表明：θ与椭圆沟道长、短半轴、钢球半径、钢球回转半径、偏心距、摆角以及转角有关，θ的6次波动是导致汽车行驶过程中振动和噪声的主要原因.     

并联耦合摆的准周期运动

自然界中存在着非常多的相互作用振动系统,正是由于相互作用的存在使得振动系统呈现丰富的动力学行为.因此,无论在基础科学领域还是工程领域中,对有相互作用的振动系统的运动规律进行研究是非常重要的.并联耦合摆是一种通过力的相互作用从而实现振动系统相互作用的装置,其具有结构简单、演示效果直观的特点.本论述基于并联耦合摆理论模型,利用数值方法研究了在较大摆角下并联耦合摆的运动规律.通过分析该系统在较大摆角时摆球的相轨迹图象和庞加莱截面图象,笔者发现并联耦摆在较大摆角下的运动是准周期运动,该性质与摆球质量是否相同没有直接关系.     

曲柄固定铰链中心不可落脚区域与伪机构解组

关于Ⅰ型、Ⅱ型平面曲柄摇杆机构，根据图解设计法的基本原理，研究讨论了曲柄固定铰链中心点A的不可落脚区域与“伪机构解组”问题．并得出如下重要结论：在不可落脚区域选择点A时，将得到不满足源设计条件的两个“伪机构解组”，恒有伪机构的摇杆摆角、极位夹角小于源机构的摇杆摆角、极位夹角，即θ伪〈θ探、φ伪〈φ源成立，且存在“错位不连续”的机构运动连续性问题．     

有关物理圆锥摆的几点讨论

介绍了物理圆锥摆的概念，讨论了θ、L、g和ω之间的关系、摆对点和轴的动量矩以及摆中的张力。     

影响金割效应物理摆振动周期的因素

金割效应物理摆是用黄金分割法优选物理摆周期极值的自制仪器,摆的振动周期是重要的物理量,也是测量的主要参数.当存在空气阻尼、摆角过大或增加配重时都会使周期发生变化,只有把握好影响物理摆的振动周期的各种因素, 才能保证测量结果的准确可靠,收到良好的效果.     

基于MSC.visualNastran 4D模型的直线一级顺摆实时控制与仿真研究

在基于动力学分析的MSC.visualNastran 4D界面上建立了一级顺摆三维模型.利用Simulink对其进行了仿真分析,控制小车按给定的运动规律运动的同时,保持摆杆的自由下垂状态.仿真分析结果表明了所提基于MSC.visualNastran 4D的直线一级顺摆模型Simulink仿真方法的有效性,为一级顺摆实验装置的工作参数和结构设计参数提供了理论依据.     

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.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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