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SS4改型机车闸缸压力对电阻制动的影Ⅱ向及改进措施
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作者 邢甫东 《铁道建设》 2010年第3期49-51,共3页
针对SS4改型电力机车在电阻制动工况下,在“电空切除”和“空电联合切除”的情况下,配合使用空气制动时闸缸压力不能自动缓解,影响电阻制动的使用,分析原因并提出了相应的改进措施。
关键词 电阻制动 改型机 压力 车闸 制动工况 电力 空气制动
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某改型机进气道方案阶段造型设计
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作者 李向维 《西飞科技》 1999年第2期36-40,共5页
介绍了某改型飞机更换发动机所带来的进气道重新设计问题。对原型机进气形式,进气道几何结构特征进行了分析,阐述了改型飞机进气道设计所受到的限制,具体设计方案,设计手段以及对设计方案的初步评审结论。
关键词 设计 进气道 造型设计 改型机
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歼七改型飞机旋转试验设计
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作者 李永富 《航空与航天》 2000年第1期10-14,共5页
关键词 旋转天平 战斗 歼7改型机 旋转试验模型 风洞
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离心压气机改型设计及扩压器前掠分析
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作者 史家伟 杜强 朱俊强 《风机技术》 2014年第4期35-43,共9页
本文主要研究单级离心压气机的改型设计,并采用数值方法对楔形扩压器前掠展开了详细研究。在保持原有压气机叶轮外径不增加、流量和设计转速不变的条件下,将压比由4.0提高到4.5。在设计离心叶轮时,首先需要确定叶轮后弯角,为了真实评估... 本文主要研究单级离心压气机的改型设计,并采用数值方法对楔形扩压器前掠展开了详细研究。在保持原有压气机叶轮外径不增加、流量和设计转速不变的条件下,将压比由4.0提高到4.5。在设计离心叶轮时,首先需要确定叶轮后弯角,为了真实评估叶轮后弯角对离心压气机效率和稳定性的影响,详细设计了后弯角为20°,25°,30°和35°的三维叶轮以及相匹配的楔形扩压器,最终选择35°后弯角叶轮。其次,后弯角为35°叶轮的设计点压比相对于设计目标偏低,将hub处弯角减小到30°达到增加设计点压比。最后,考虑到楔形扩压器各截面载荷的不同,研究了楔形扩压器前掠对性能影响。 展开更多
关键词 离心压气改型设计 楔形扩压器 扩压器前掠
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方向舵悬挂的设计研究
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作者 何晓春 梁芳明 陈丽媛 《科技视界》 2013年第32期113-113,共1页
0引言某某型机研制中.在某某台架上进行操纵系统试验时.发现方向舵有下沉现象。这一现象反映在方向舵悬挂支臂与方向舵前缘开口上下间隙偏离,即上间隙小,下间隙大。在飞机结构部件对接装配后,再次出现同样问题.值得注意的是.当... 0引言某某型机研制中.在某某台架上进行操纵系统试验时.发现方向舵有下沉现象。这一现象反映在方向舵悬挂支臂与方向舵前缘开口上下间隙偏离,即上间隙小,下间隙大。在飞机结构部件对接装配后,再次出现同样问题.值得注意的是.当方向舵与其操纵系统相连后.“下沉”消失.方向舵恢复正确位置。这说明方向舵受到操纵系统上顶作用。从“下沉”到…恢复”.从个别到一般.反映出方向舵及其操纵系统.无论是原形机还是改型机.都存在设计问题甚至潜在的隐患。 展开更多
关键词 方向舵 设计 悬挂 操纵系统 下沉现象 间隙小 结构部件 改型机
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F/A-18E/F雷达已作好升级准备
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作者 立早 《航空电子技术》 2003年第2期53-53,共1页
美国海军和Raytheon公司2003年年初计划在夏季继续生产之前希望克服最后的障碍,以进行F/A-18E/F的新雷达的关键试验。 Raytheon公司从2000年起就开发APG-79有源电子扫描阵列(AESA)系统。据海军雷达项目主管部门称。
关键词 F/A-18E/F 电子战改型机 技术改进 雷达告警接收 合成孔径雷达
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A general simulation model developing process based on five-object framework
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作者 胡安斌 伞冶 +1 位作者 陈建明 陈永强 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2003年第4期380-384,共5页
Different paradigms that relate verification and validation to the simulation model have different development process. A simulation model developing process based on Five-Object Framework (FOF) is discussed in this p... Different paradigms that relate verification and validation to the simulation model have different development process. A simulation model developing process based on Five-Object Framework (FOF) is discussed in this paper. An example is given to demonstrate the applications of the proposed method. 展开更多
关键词 model SIMULATION FOF (Five-Object Framework)
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The transformation of China's economic and government functions
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作者 ZHOU Yu-feng 《Chinese Business Review》 2010年第2期56-60,共5页
The content of China's economic transformation is not single, and this article argues that it includes three parts. The first is the reform of economic system, the second is the change in the pattern of economic grow... The content of China's economic transformation is not single, and this article argues that it includes three parts. The first is the reform of economic system, the second is the change in the pattern of economic growth, and the third is the adjustment of economic structure. Government is the leading force of China's economic transformation, and repeated reform of government institutions has brought about some changes to government functions. But problems are obvious that lag changes of government functions have become an obstacle in China's economic transformation. This article describes the historical evolution and the reality of China's economic transformation, and analyzes the main reasons of lag changes in government functions, and reveals that the transformation of government functions is the key for successful transformation of China's economy. 展开更多
关键词 TRANSFORMATION China's economy government functions
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Simulation of Spin-3/2 Blume-Capel Model on a Cellular Automaton with Heating and Cooling Algorithm
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作者 N.Seferoglu 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第7期168-172,共5页
The spin-3/2 B1ume-Capel model is studied using the heating and cooling algorithms improved from the Creutz cellular automaton (CCA). The calculations are done on various sizes of the simple cubic lattice in the 0 ... The spin-3/2 B1ume-Capel model is studied using the heating and cooling algorithms improved from the Creutz cellular automaton (CCA). The calculations are done on various sizes of the simple cubic lattice in the 0 ≤ D/J ≤ 5 parameter region. The phase diagram of the model and temperature variation of the thermodynamic quantities are obtained. We confirm the existence of a critical end point within the heating calculations. However, in contrast to the heating calculations, we do not obtain the first-order line at low temperature with cooling algorithm calculations. The results are compared with those of other theories. 展开更多
关键词 spin-3/2 Blume-Capel model cellular automaton simple cubic lattice
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Analytical Evaluation of the Energy Losses of an Air Source Heat Pump Water Heater: A Retrofit Type
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作者 Stephen Tangwe Michael Simon Edson Meyer 《Journal of Energy and Power Engineering》 2014年第7期1251-1257,共7页
ASHP (air source heat pump) water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units ... ASHP (air source heat pump) water heater is a renewable and energy efficient device used for sanitary hot water production. The system comprises of a storage tank and heat pump connected by pipes. These major units can either be compact as in the integrated model or split as in the retro-fit model. In this research, the analysis of energy losses was performed using SIRAC (the Southern African refrigeration and air conditioning) residential split type heat pump of 1.2 kW input power to retrofit a 200 liter high pressure kwikhot storage tank without hot water being drawn off for the entire monitoring period. Likewise to experimentally determine the losses DAS (data acquisition system) was designed and built to measure Ta (ambient temperature; RH-relative humidity), RH, To (ASHP outlet water temperature), Ti (ASHP inlet water temperature) and Vh. (volume of water heated by ASHP unit).The results showed that the heat energy gain to compensate standby losses could range from 1.8 kWh to 2.1 kWh with the corresponding electrical energy used by ASHP water heater ranging from 0.55 kWh to 0.66 kWh. The standby losses depend primarily on the Vh, the Ta and the RH while the influence of (To - Ti) is secondary. The results can be of valuable interest to manufacturer of retrofit ASHP unit for hot water production when matching the electrical energy required to compensate for the standby losses. 展开更多
关键词 ASHP DAS TA Vh To Ti
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两款新型涡桨发动机
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作者 张正国 《国际航空》 2009年第8期66-67,共2页
目前涡桨发动机市场中出现了两款新的型号:罗罗公司的RR500涡桨发动机和GE公司的沃尔特M601-80H涡桨发动机。两者的功率均在1000千瓦以下,适用于通用航空领域。两款新发动机的研制,是对现有涡桨发动机系列的有效补充,可用于不同的... 目前涡桨发动机市场中出现了两款新的型号:罗罗公司的RR500涡桨发动机和GE公司的沃尔特M601-80H涡桨发动机。两者的功率均在1000千瓦以下,适用于通用航空领域。两款新发动机的研制,是对现有涡桨发动机系列的有效补充,可用于不同的新机型和改型机。 展开更多
关键词 涡桨发动 GE公司 罗罗公司 航空领域 改型机
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服役中的苏霍伊战斗机
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作者 丛志鹏 《海陆空天惯性世界》 2005年第08M期56-65,共10页
装备部队 1984年,苏-27飞机开始装备前苏联空军部队。还在该机的研制阶段,有关方面就做出了决定,要用苏-27飞机装备空军和国土防空军的战斗航空兵团。同时,装备空军前线航空兵和国土防守军航空兵的飞机实际上是同一型飞机,并没有... 装备部队 1984年,苏-27飞机开始装备前苏联空军部队。还在该机的研制阶段,有关方面就做出了决定,要用苏-27飞机装备空军和国土防空军的战斗航空兵团。同时,装备空军前线航空兵和国土防守军航空兵的飞机实际上是同一型飞机,并没有为空军和国上防空军研制任何专门的改型机。 展开更多
关键词 战斗 苏-27飞 空军部队 装备 服役 航空兵团 研制阶段 前苏联 改型机
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改型不改价
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作者 靖程 《电脑时空》 2008年第11期36-36,共1页
惠普Deskjet F2288喷墨多功能一体机是继惠普Deskjet F2188喷墨多功能一体机之后推出的一款改型机。如果单从外观上对两款机型进行比较,它们除了颜色稍有差异外,在体形和控制面板设计上基本没有太大的出入,但是在实际使用后你会发现... 惠普Deskjet F2288喷墨多功能一体机是继惠普Deskjet F2188喷墨多功能一体机之后推出的一款改型机。如果单从外观上对两款机型进行比较,它们除了颜色稍有差异外,在体形和控制面板设计上基本没有太大的出入,但是在实际使用后你会发现,F2288在功能上还是有了不小的改进,在目前价格一致的前提下,F2288当然是用户的更好选择。 展开更多
关键词 改型机 惠普DESKJET 喷墨多功能一体 面板设计
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Effects of renal denervation on blood-pressure response to hemorrhagic shock in spontaneously hypertensive rats 被引量:2
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作者 Xiao-Na Cai Chao-Yi Wang +1 位作者 Yuan Cai Fang Peng 《Chinese Journal of Traumatology》 CAS CSCD 2018年第5期293-300,共8页
Purpose: Renal denervation (RD) has been demonstrated to be an effective approach to reduce blood pressure for those with resistant hypertension. Yet, we aimed to explore the effect and possible mech- anism of RD o... Purpose: Renal denervation (RD) has been demonstrated to be an effective approach to reduce blood pressure for those with resistant hypertension. Yet, we aimed to explore the effect and possible mech- anism of RD on blood-pressure response to hemorrhagic shock in spontaneously hypertensive rats. Methods: A total of 48 male spontaneously hypertensive rats were randomized to three groups: study group, sham-operation group and control group. RD was achieved by cutting off renal nerves and swabbing phenol on it. Ten weeks after RD, 8 rats in each group were sacrificed to collect the kidney and heart tissues. The remaining rats were subjected to an operation to induce hemorrhagic shock which would lead to 40% loss of total blood volume, and observed for 120 min. The serum concentration of norepinephrine was measured before and three weeks after RD. Results: The blood-pressure and norepinephrine levels were reduced significantly after RD (p 〈 0.05), Systolic blood pressure and diastolic blood pressure of the surgerygroup were higher than those in the sham and control groups at 15, 30 and 45 min after hemorrhagic shock (p 〈 0.05), while no significant difference was observed at 60, 90 and 120 min (p 〉 0.05). Additionally, the beta-1 adrenergic receptor (β1 -AR) in the study group was significantly higher than those in the other two groups (p 〈 0.05) after hemorrhagic shock. Conclusion: This study demonstrated that RD could to some extent improve blood-pressure response to hemorrhagic shock in an established model of severe hemorrhagic shock in spontaneously hypertensive rats. The mechanism might be associated with uo-regulation of β1-AR. 展开更多
关键词 Renal denervation HEMORRHAGE Beta-1 adrenergic receptor Spontaneously hypertensive rats
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Modified series model for cross-plane thermal conductivity of short-period Si/Ge superlattices 被引量:1
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作者 FENG Yuan LIANG XinGang 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2015年第6期66-73,共8页
Superlattices have great application potentials in thermo-electric materials and solid laser techniques.Their complicated heat transport mechanisms due to size effects,multi-interfaces and mini-band are very important... Superlattices have great application potentials in thermo-electric materials and solid laser techniques.Their complicated heat transport mechanisms due to size effects,multi-interfaces and mini-band are very important issues for the prediction of thermal conductivity.In this paper,the short-period Si/Ge superlattices are investigated by a modified series model based on the Debye-Callaway description.The Lambert Law is used to describe the phonon emission within hemisphere space.In addition,the phonon interface transmission coefficients obtained from the phonon wave packet simulation are incorporated into boundary condition of the model,which removes the fitting parameters in the model.Better agreement with experiment is obtained.The effects of temperature,wavelength-dependent phonon transmission,superlattice periods,as well as the thickness of Ge layer are considered in this paper. 展开更多
关键词 SUPERLATTICES thermal conductivity Debye-Callaway model Lambert Law
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A modified creep index and its application to viscoplastic modelling of soft clays 被引量:1
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作者 Qi-yin ZHU Ze-xiang WU +3 位作者 Yan-ling LI Chang-jie XU Jian-hua WANG Xiao-he XIA 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2014年第4期272-281,共10页
Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index Cae with increasing soil density. Based on all selected and conducted experimental results, a... Conventional consolidation tests on reconstituted specimens of numerous natural soft clays show a decreasing of creep index Cae with increasing soil density. Based on all selected and conducted experimental results, a modified creep index Cae* defined in double logarithmic plane lge-lgt, was plotted for various clays, from which Cae* can be assumed as a constant for different soil densities. Then, the modified creep index was applied to a newly developed elastic viscoplastic model. In this way, the modified creep index Ca* can naturally take into account the nonlinear Cae revealing the influence of soil density in the soil assemblies without additional parameters. Finally, the enhanced model was incorporated into the finite element code ABAQUS and used to simulate a consolidation test and a test embankment. The improvement of simulations by the modified creep index was highlighted by comparing simulations using the conventional creep index Cae. 展开更多
关键词 Clays CREEP Consolidation test EMBANKMENT Finite element method VISCOPLASTICITY
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Modification of k-ω Turbulence Model for Predicting Airfoil Aerodynamic Performance
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作者 PENG Bo YAN Hao +1 位作者 FANG Hong WANG Ming 《Journal of Thermal Science》 SCIE EI CAS CSCD 2015年第3期221-228,共8页
Predicting wind turbine S825 airfoil's aerodynamic performance is crucial to improving its energy efficiency and reducing its environmental impact. In this paper, a numerical simulation on the wind turbine S825 airfo... Predicting wind turbine S825 airfoil's aerodynamic performance is crucial to improving its energy efficiency and reducing its environmental impact. In this paper, a numerical simulation on the wind turbine S825 airfoil is con- ducted with k-to turbulence model at different attack angles. By comparing with experimental data, a new method of modifying k-to model is proposed. A modifying function is proposed to limit the production term in ω equation based on fluid rotation and deformation. This method improves turbulent viscosity and decreases separating re- gion when the airfoil works at large separating conditions. The predictive accuracy could be improved by using the modified k-to turbulence model. 展开更多
关键词 S825 airfoil SEPARATION k-ω model aerodynamic performance NON-EQUILIBRIUM
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Advance in research of several types of streaming of pulse tube refrigerators 被引量:1
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作者 GU Chao TANG JianBo +1 位作者 WANG JunJie ZHOU Yuan 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第11期2690-2701,共12页
The pulse tube refrigerator (PTR) is a promising small-scale cryocooler. This paper first briefly introduces the history of the pulse tube refrigerator. It has pointed out that technology improvements and theoretica... The pulse tube refrigerator (PTR) is a promising small-scale cryocooler. This paper first briefly introduces the history of the pulse tube refrigerator. It has pointed out that technology improvements and theoretical developments of the pulse tube refrig- erator closely relate with the internal streaming effects. Then the discovering history and classification of the streaming or DC (direct current) flow effect are summarized. It proposes for the first time that the physical significance of the streaming con- tains the driving mechanisms and the transport mechanisms. It demonstrates that the driving mechanisms are the asymmetry of fluid flow and temperature while the transport mechanisms are a loop or vorticity, which transmits nonlinear dissipations. The important advancements have been made over the past two decades all over the world in research of streaming of the pulse tube refrigerator including Gedeon DC flow, Rayleigb streaming, the third type of DC flow and the regenerator circulation. With regard to Gedeon DC flow, theoretical and experimental analyses have been made and different suppression methods are summarized. In the aspect of Rayleigh streaming, it mainly focuses on the analytical solution of the second-order mass flow and the research of tapered pulse tubes. In particular, limited research on the third type of DC flow and regenerator circulation is presented. The experimental measurement techniques of streaming also are summarized. Finally, this paper briefly discusses the key scientific and technical issues of the current research, and foretells the future development trends of streaming research in PTR. 展开更多
关键词 pulse tube refrigerator STREAMING asymmetry closed loop VORTICITY
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