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深施型液态施肥机扎穴机构优化设  [PDF]
王金峰,王金武,葛宜元,刘亚华,鞠金艳
农业机械学报 , 2010,
Abstract: 为实现液态施肥机高速作业,设计了一种结构简单、运动平稳的椭圆齿轮行星系作为液态施肥机的扎穴机构。对该机构进行运动学分析,建立了数学模型,以穴距200mm和入土深度120~150mm为寻优目标,应用VisualBasic6.0软件编程得出满足机构运动要求的最优参数范围为:喷肥针尖和行星轮轴连线与行星架的初始夹角-45°~-40°、行星架初始角位移40°~50°、喷肥针尖与行星轮轴心距离280~300mm,此时椭圆齿轮长半轴29.364mm、齿数23、短半轴与长半轴比0.958,正圆齿轮半径25mm。从优化工作参数中选择一组参数设计扎穴机构,应用Pro/E软件进行仿真。结果表明,根据优化参数设计的扎穴机构能够满足穴距和入土深度的设计要求。
?械??器  [PDF]
地质与勘探 , 1957,
Abstract: ?械??器是用来消除在爆破??生的灰尘使用的一种简单器械。它的?造(?附图)是在直?33.5公厘的管子上,按有4个?水器所?成的。共制造方法是将蓝子(2)焊在怜子的一端(见
考虑螺旋桨滑流影响的双发涡桨飞机气动特性研究
Aerodynamics Analysis of Twin-Turboprop Aircraft with Propeller Slipstream Effects Considered
 [PDF]

王伟,段卓毅,耿建中,王斌,丁兴志
- , 2017,
Abstract: 螺旋桨滑流与飞机其他部件之间存在着复杂的气动干扰,将对双发涡桨飞机的气动特性产生较为显著的影响。以双发涡桨飞机为研究对象,采用多重参考系滑移网格技术进行流场数值模拟,研究了不同拉力系数下螺旋桨滑流以及滑流区内尾翼法向位置对全机气动特性的影响。研究结果表明:螺旋桨滑流效应将增加全机升力和阻力,降低全机升阻比,并导致小迎角区域俯仰力矩不稳定;随着拉力系数的增加,全机最大升力系数可增加40%,阻力系数增加150%,升阻比可降低50%,小迎角俯仰力矩拐点可增加8°,静稳定裕度可降低30%;合理地下移尾翼法向位置,可有效地利用螺旋桨滑流的影响,改善其俯仰力矩特性。研究结果对双发涡桨飞机的总体气动设计具有一定的工程指导价值。
Aerodynamic interaction of propeller slipstream with aircraft parts will lead to significant influence on the complete twin-turboprop aircraft. Taking the twin-turboprop aircraft for example, the effects on the complete aircraft due to propeller slipstream and the normalized translation of horizontal wing under different thrust coefficient are studied by numerical simulation based on multiple reference frames (MRF) techniques. The research results and their analysis show preliminarily that:due to the effects caused by slipstream of propellers, the lift and drag will increase correspondingly, while the lift-drag ratio will decrease and the pitching moment will become unstable at the small AOA; with the increasing of thrust coefficient, the lift coefficient will increase by 40%, the Cd will increase by 150%, the lift-drag ratio will decrease by 50%, the inflection point at small angle of attack will increase by 8 degrees and the pitching static margin will decrease by 30%;rationally moving the horizontal wing down will make use of the slipstream effects, which will improve the pitching moment characteristics. The investigation is believed to be of some reference value to the design of twin-turboprop aircraft
青贮玉米收获机打捆装置自动控制系统设  [PDF]
丛宏斌,李汝莘,韩新月,李明利,范修文,赵何
农业机械学报 , 2009,
Abstract: 青贮玉米收获机可在玉米摘穗的同时,将切碎的秸秆打成圆捆,以便于青贮。为提高作业效率、简化机手操作流程,设计了一套喂料与送绳自动控制系统,该系统由传感检测元件、控制电路及执行机构3部分组成。采用四路换向开关作为传感检测元件,并结合RS去抖电路,可有效提高控制系统工作可靠性。执行元件为两电磁离合器,接收控制电路的输出信号,完成对喂料和送绳过程的实时控制。试验表明:该系统工作安全、可靠,料捆成捆率达到100%;与手动控制方式相比,有效强化了料捆密度控制的准确性,使机具的作业效率提高
The propeller and the frog  [PDF]
Margaret Pan,Eugene Chiang
Physics , 2010, DOI: 10.1088/2041-8205/722/2/L178
Abstract: "Propellers" in planetary rings are disturbances in ring material excited by moonlets that open only partial gaps. We describe a new type of co-orbital resonance that can explain the observed non-Keplerian motions of propellers. The resonance is between the moonlet underlying the propeller, and co-orbiting ring particles downstream of the moonlet where the gap closes. The moonlet librates within the gap about an equilibrium point established by co-orbiting material and stabilized by the Coriolis force. In the limit of small libration amplitude, the libration period scales linearly with the gap azimuthal width and inversely as the square root of the co-orbital mass. The new resonance recalls but is distinct from conventional horseshoe and tadpole orbits; we call it the "frog" resonance, after the relevant term in equine hoof anatomy. For a ring surface density and gap geometry appropriate for the propeller Bl\'eriot in Saturn's A ring, our theory predicts a libration period of ~4 years, similar to the ~3.7 year period over which Bl\'eriot's orbital longitude is observed to vary. These librations should be subtracted from the longitude data before any inferences about moonlet migration are made.
研究高聚物機械性能的熱-機械方法
徐紀平,錢保功
高分子学报 , 1958,
Abstract: 非晶態綫型聚合物,共有三個物理-機械狀態:玻璃態、高彈態和粘流態。從玻璃態轉變到高彈態的溫度稱為玻璃化溫度(以T_g表示),從高彈態轉變到粘流態的溫度稱為流動溫度(以T_j表示)。
Spectral characterizations of propeller graphs  [PDF]
Xiaogang Liu,Sanming Zhou
Mathematics , 2012,
Abstract: A propeller graph is obtained from an $\infty$-graph by attaching a path to the vertex of degree four, where an $\infty$-graph consists of two cycles with precisely one common vertex. In this paper, we prove that all propeller graphs are determined by their Laplacian spectra as well as their signless Laplacian spectra.
一种超体积准则多目标遗传算法的螺旋桨叶片优化方法
An optimization method of propeller blade based on the hypervolume criterion multi-objective genetic algorithm
 [PDF]

潘志榕,朱光宇,伊德景
福州大学学报(自然科学版) , 2018, DOI: 10.7631/issn.1000-2243.17072
Abstract: 为改善螺旋桨叶片敞水效率,用结合超体积准则的多目标遗传算法优化螺旋桨桨型设计. 优化过程中,桨叶形状用B 样条曲线拟合,利用面元法建立桨型性能模型. 将计算螺旋桨升力和阻力转化为降低阻升比、桨型面积差和压力方差三个优化目标,得到优化后的螺旋桨剖面形状,并将优化前后的螺旋桨进行流体分析. 结果表明,超体积准则结合多目标遗传算法进行螺旋桨叶片优化是有效的. 优化后的桨型在面积差变化较小的情况下三个目标均有明显改进,螺旋桨水动力性能达到预期目标,敞水效率提升12%.
In order to improve the open water efficiency of the propeller,the propeller type is optimized with the hypervolume criterion multi-objective genetic algorithm. In the optimization process,the blade shape is curve fitted with B-spline,and the propeller type performance model is established with surface panel method. The lift and drag force of the propeller is transformed into three optimization objectives: reducing the drag lift ratio,the propeller area difference and the pressure variance. With the proposed method,the propeller profile after optimization is obtained. Then the propeller before and after optimization are analyzed with fluid analyzing method. The calculation results indicate that the hyper volume criterion multi-objective genetic algorithm is effective in the propeller blade optimization,the three objectives of the optimized propeller type have been improved obviously,the hydrodynamic performance of the propeller reaches the anticipated goal,and the open water efficiency increases 12%
Magnetic propeller in symbiotic stars  [PDF]
Alexander Panferov,Maciej Mikolajewski
Physics , 2000,
Abstract: Rapidly spinning magnetic white dwarfs in symbiotic stars may pass through the propeller stage. It is believed that a magnetic propeller acts in two such stars CH Cyg and MWC 560. We review a diversity of manifestations of the propeller there. In these systems in a quiescent state the accretion onto a white dwarf from the strong enough wind of a companion star is suppressed by the magnetic field, and the hot component luminosity is low. Since the gas stored in the envelope eventually settles to the corotation radius the star-propeller reveals itself by long-time outbursts, short-time brightness dips, strong amplitude flickering, ejection of a powerful wind and jets. The envelope appears to be stratified and inhomogeneous because of the shock pumping of the propeller. At this stage, at which catastrophic transitions to the accretion stage and back are possible, the release of energy and angular momentum of the white dwarf is maximum. Using this property, we estimate the magnetic field strength of the white dwarfs in CH Cyg and MWC 560 to be of order $10^8$ G. The most spectacular property of these stars - jets - is inherently connected with the propeller. This suggests hydromagnetic models of jet acceleration.
農藥用械的使用原理
曹驥
科学通报 , 1951,
Abstract: 農藥用械的使用到今天也不過六十幾年的歴史,在我國的歴史更短,不過三十幾年。解放後因為人民政府對於農業病虫害問題的重視,農藥用械從過去的幾乎全部仰賴舶來品已改為逐步走上自給,同時地方性的創造也不斷加多,這是非常值得我们高興和重視的。另方面作者也願意趁此機會把兩種主要的農藥用械——噴霧器和噴粉器一的使用原理和應加注意之點做一個約略的說明,對今後農藥用械的發展前途想必是不無補益的。
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