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1.
对计算机辅助气动系统逻辑设计进行了深入研究,选择逻辑综合的方法作为计算机辅助气动系统逻辑设计的基础理论基本方法,采用立方符号表述逻辑函数,把逻辑运算表示为立方的相交、相容及锐积运算,提出用判断最小项来完成对给定程序的判和校正,进而实现了计算机辅助逻辑综合,得到了的逻辑设计结果。  相似文献   

2.
设计了一种新颖的能实现自动间隙回转的气动组合装置XST型气动分度盘,阐述了该装置的工作原理、结构特点、气动控制回路和确定主要参数的设计计算方法,同时对本设计中采用的缓冲方式进行了相关分析和比较。  相似文献   

3.
本文主要介绍了气动测量的基本原理,锥度玻璃管-浮标的工作原理,倍率调整和零位调整的工作原理,小锥孔角度的气动测量原理及气动测量的误差分析,最后提出提高测量精度的措施。  相似文献   

4.
通过输入单频信号及风压信号,检验气动总管对输入信号的气动平均性能,试验结果与计算得到的理论值吻合得较好.考察了输入管位置对输入信号气动平均性能的影响.归纳了影响气动总管气动平均性能的因素,认为输入管位置对气动总管的工作性能影响很小,并指出气动总管制作时密封性的重要性.  相似文献   

5.
海上风力机等大型风电设备叶片较长,所承受气动载荷较大,易产生变形,影响气动性能和运行稳定性。针对这一问题,以美国NREL实验室的5 MW大型风电叶片为例,对其进行以各截面翼型形线、安装角及额定功率下桨距角为设计变量的高效低载三维优化。优化基于动量叶素理论和多岛遗传算法,以叶根弯矩最低和风能利用率最大为优化目标,并将优化叶片与原始叶片于变桨、变风况下的气动性能进行对比。结果表明:在设计工况下,相较于原始叶片,优化叶片在保证高气动效率的同时叶根弯矩降低了5%;变风况条件下,变桨前优化叶片的风能利用率平均提升了1%,叶根弯矩平均降低了5.8%,变桨后优化叶片的叶根弯矩平均降低了4%。  相似文献   

6.
为了优化车辆开发过程的有效性,数值气动声学分析法的实施和应用对汽车制造商来说变得越来越重要。提出了一种结合延迟分离涡流模拟和基于Lighthill方程及声学扰动方程的有限元模型混合数值工具,应用OpenFOAM和Actran软件实现了基于声学有限元法的近场声源区提取及声学压力脉动计算,并尝试应用于车顶扰流板及后视镜区域的气动噪声计算及分析。在兰博基尼Urus车型上,研究了不同车顶扰流板设计的气动声学行为,将仿真结果与斯图加特大学气动声学全尺寸风洞的实验结果进行比较,发现了令人信服的相关性。此外,探讨了扰流板上的主要噪声产生机制,研究了汽车表面压力波动水平随几何形状改变的变化情况。  相似文献   

7.
本文在气动测量进行理论分析的基础上,研制出一种新型气动量仪,它不仅能用于测量尺寸误差、形状误差,而且还可以测量相互位置误差。  相似文献   

8.
多片尾翼布局弹箭气动特性数值计算   总被引:4,自引:1,他引:4  
用数值模拟方法研究多片尾翼布局弹箭的气动特性.以三维Navier—Stokes方程为控制方程,用CFD方法对4片、6片与8片平直形尾翼和卷弧形尾翼弹箭的流场进行数值模拟研究,得到的气动特性结果与风洞实验结果基本吻合,为多片尾翼布局弹箭的气动设计及尾翼片数的合理选择提供了依据。  相似文献   

9.
自动调节气压卸荷导轨的研究   总被引:3,自引:2,他引:3  
自动调节气压卸荷导轨利用压缩空气支承部分导轨载荷,以降低导轨面上的正压力,从而降低摩擦力。当载荷变化时,气压也随之而变,以保持导轨面的正压力和摩擦力基本不变。这种导轨可以降低进给功率,提高工作台的定位精度和导轨的精度保持性,刚度比普通滑动导轨和滚动导轨高很多,抗振性高于滚动导轨。对它的加工要求,与对普通滑动导轨相同,远低于液体静压导轨。工作介质为空气,不污染环境,不需回收。可广泛地应用于精密和重型机床如坐标镗床、数控机床和加工中心。  相似文献   

10.
无控滑翔子弹的气动设计   总被引:2,自引:0,他引:2  
采用理论与实验相结合的方法进行了滑翔子弹的气动外形设计。风洞试验结果表明,尾翘确有使子弹滑翔的作用。所采取的3项预防滚转措施显著地减小了卷弧翼的滚转力矩。弹道仿真结果表明,滑翔子弹的飞行距离约比常规尾翼子弹增大了80%,可以有效地扩大子弹的撒布范围  相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
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.  相似文献   

14.
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.  相似文献   

15.
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。  相似文献   

16.
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.  相似文献   

17.
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.  相似文献   

18.
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-  相似文献   

19.
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-  相似文献   

20.
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  相似文献   

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