BQ1010A型单臂刨床进给系统的数控改造设计

论述了ＢＱ１０１０Ａ型单臂刨床数控改造的控制原理，进行了进给系统最佳传动比的计算，完成了控制系统硬件、软件设计及机械部分的改造设计，使刨床的最小进给量由原来的０．６０ｍｍ减小到０．０１ｍｍ，提高了刨床的使用范围和零件的加工精度．该设计方法可以经济地、快速地获得机床精度，提高刨床的性能价格比．     

B2010龙门刨床电气改造方案概述

电动机调速分为直流调速和交流调速两种．交流异步电机虽然机构简单、维修方便、价格便宜，但调速性能较差，如今随着变频调速技术的发展和广泛应用，交流变频调速技术逐渐成为取代直流调速的主流。对于老、旧设备，通过改造可以使它焕发青春，我公司对B2010龙门刨床电气改造后，其性能达到刨床加工的工艺要求，同时节约了能源     

变频调速系统在龙门刨床上的应用

针对B2016A九米龙门刨床主传动存在的问题，采用变频调速系统对机床进行了主传动改造，充分发挥了大型龙门刨床的效率并降低了能耗。     

木工压刨床噪声机理的研究

本文通过对木工压刨床噪声机理的分析研究，指出其空气动力性噪声由旋转、排气和涡流噪声组成，并给出了相应的物理及数学模型和声功率关系式，确定了整机声源特性，为从根本上控制木工压刨床的噪声提供了理论依据。     

木工压刨床噪声源识别

本文通过对MB10A9型木工压刨床的实验研究,运用现代测试手段和数据处理方法,找出了木工压刨床的噪声源,通过噪声形成机理分析,确定了木工压刨床的声源特性,在此基础上采取了一些降噪措施,并收到了良好的效果。     

基于PLC的龙门刨床直流调速系统改造

通过对龙门刨床工作台的工作原理和原调速系统的工作特性的分析,提出应用PLC和可逆直流调速器改造龙门刨床电气控制系统的实现方案,将发电机组及扩大机控制的龙门刨床改造成全数字智能化的直流PLC电气控制系统,适用于各种型号的老式刨床控制。     

论龙门刨床的变频调速

从分析大型龙门刨床的工作特点及主传动系统出发，研究了该种机械的变频调速设计方法，获得了明显的经济效益.     

龙门刨床若干关键技术指标的改进

对龙门刨床进行改造时，从加快传动系统的过渡过程以及系统的静态精度、限流保护等方面着手，降低系统的飞轮转矩，采用PI控制器对系统进行无静差的调速，然后采用电流截止负反馈的方法，使得系统具有过渡时间短、加工精度高以及自动限流保护操作的优良性能．     

多目标最优化技术在刨床设计中的应用

将多目标最优化技术中的分层序列法应用于机械刨床设计的步骤是：先建立寻优数学模型，找出设计变量、目标函数和约束条件，通过迭代得到最优解。利用此方法进行设计，关键在于将各分目标函数按其重要程度排序，逐次求出最优解，既简化了求解过程，又保证了求解精度，本文用设计实例说明设计的全部过程，与其他方法相比，设计的刨床传动结构更为紧凑和精确，具有很高的实用价值。     

浅谈用PLC对B2012A系列龙门刨床的电气控制改造

通过分析龙门刨床传统控制改造的必要性提出课题,简要介绍了龙门刨床的基本结构及控制要求和改造前后的差别,阐述了用PLC等工控设备对传统电气控制技改的前景广阔。     

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     

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