耕整机操作手把的模态分析及结构动力修改设计

本文对耕整机操作手把进行模态分析，结果表明第二阶模态频率与第三阶模态分别与发动机的一阶惯性力和二阶惯性力频率相耦合。为避开这种耦合，本文进行了刚度、质量的局部修改。结果表明手把振动幅度有较大的下降。     

宾川县微耕机推广见成效

微耕机是近年来推广使用的一种小型农田作业耕整机械，以其体积小、重量轻(100kg左右)、多功能而见长。宾川县农机管理站立足农机工作，始终不忘农机为农业生产服务这一宗旨，于1999年11月引进了一台四川产合盛12-105牌微耕机示范推广。通过不同土质地点耕整地后总结，机耕与牛犁、人工碎土相比每亩可节约30元，且耕深、土粒大小均能满足农艺要求。     

罐头嘴镇:标本兼治抓好安全生产

汉寿县罐头嘴镇地处西湖大垸,是一个拥有3万多人口的农业大镇。现有粘土砖厂2家、加油站2家、烟花爆竹经营门店61家;农村运输及农机3420台(部),其中手扶拖拉机103台,联合收割机62台,耕整机1112台;机动驾驶车辆1427台,农用机动车辆104台,客车18台,货运车5台。全镇安全生产线长面广,以农机安全隐患最为突出。     

微耕机操作使用注意事项

近年来,外出务工人员日益增多,农村劳动力在不断转移。得益于国家购机补贴政策,耕整机、微耕机等小型耕作机械因其轻巧实用、操作简便又价格不贵(补贴之后,个人仅出2000～3000元即可购买)增长很快。在实际使用过程中,因多数微耕机购买人员在购买前根本未接触过农机,买后就随便使用,有时新买的机具刚使用就发生这样那样的问题,影响购机户心情,也耽误农时。笔者认为,农机户在操作使用微耕机中要注意几个方面     

山区农业机械安全管理存在的问题及建议

<正>永顺县位于湘西自治州北部,辖区总面积3810.6325平方公里,2015年乡镇区划调整后,下辖11乡12镇。境域内地势险峻,山峦起伏,溪河纵横。地貌呈山地、山原、丘陵、岗地及向斜谷地等多种类型。近年来,随着国家对贫困山区农业机械推广的扶持以及实行的农机购置补贴政策,农业机械不仅在平原地区迅猛增加,在山区也呈逐年上升趋势,农业机械正呈递增状态进入千家万户。拖拉机等已成为农村生产、生活短途运输的主要工具,中小型耕整机、插秧机、收割机等代替传统生产工具发展迅猛,在种植业、养殖业等领域发挥了无可替代的作用。但是,由于农民技能缺乏、安全意识不强,加之农村道路坡陡、弯多、狭窄,且临水临崖,安全隐患十分突出,农业机械安全管理工作任务十分繁重。     

基于比例方向阀的6自由度摇摆试验台精度控制方法研究

介绍了6自由度平台的控制方法,深入研究了比例方向阀的精度,介绍了比例方向阀的工作原理,对比例方向阀的静、动态特性进行了实验测试,并提出了对称阀控制非对称缸的控制方法.对平台运动轨迹规划进行了研究,提出了轨迹规划的方法,并进行了试验.     

晶闸管整流供电的恒流源

介绍了恒流源控制电路的组成 ,分析了电路的工作原理 ,画出了各组成部分的电路图 ,建立了系统的数学模型并分析了系统的性能。     

汽车悬架的发展现状和展望

阐述了汽车悬架的发展历史和现状,着重分析了悬架的原理,给出了衡量悬架的性能指标,讨论了各种悬架的优缺点,并对未来悬架的发展做出了预测.     

童心童眼

正本期话题春天来了编辑阿姨的话:小河解冻了吗?小柳条发芽了没有?小燕子飞回来了吗?小青蛙醒了没有?小草儿冒尖了吗?小花苞探出头来了没有?春天来了!春天来了!小伙伴们,快,我们一起去寻找春天的踪迹!春天在哪里早晨,灰蒙蒙的大雾像一个巨大的纱罩(zhào),把大地上的一切都遮住了。午饭过后,我和妈妈去公园玩。我发现路两旁     

水平井中电潜泵的力学分析

阐述了电潜泵在水平井中使用时存在的问题。通过简化,得出了电潜泵在水平井弯曲段的力学模型,导出了电潜泵在水平井狗腿段的变形微分方程式。利用叠加原理,导出了套管和电潜泵的变形度计算公式,分析了电潜泵在狗腿段受到的应力,得出了应力的计算公式,并给出了简单算例。将计算结果与已有文献的结果进行了对比,两者很吻合。     

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