浅析自由式摔跤技术中的转动力

自由式摔跤是世界上最早的竞技体育运动,在中国、埃及、希腊、日本等国家的古代文明中都有记载。本文从分析转动力的基本形式及摔跤中常用的转动动作入手,具体阐述了自由式摔跤技术中转动大小和转动方向、转动支点,最后简略探析了自由式摔跤中转动力的灵活运用。

一种可倾转动力螺桨飞机的定载静稳定性研究

以一类通过重心前动力倾转实现短距起降的螺桨飞机为研究对象,研究其实现短距起降的可行性,推导了低速阶段该类飞机定载静稳定性表达式,并对其进行验证分析。结果表明:为满足定载静稳定性,重心前倾转矢量力的大小、位置以及倾转角之间相互约束,推重比T/W和倾转角θ越大,矢量力距离焦点/重心越近。该结论可为同类飞机设计提供参考。

浅析影响叉车方向盘转动力大小因素

随着叉车市场竞争的日趋激烈,叉车生产厂家为了使自己的叉车在市场中具有竞争力,他们不仅从提高叉车的性能入手,同时也十分注重叉车的外型美观、操作的舒适性、灵活性。

分析自由式摔跤技术中的转动力

在体育运动中广泛存在着转动。它符合人体运动的科学原理,充分发挥人体潜在的转动力。本文就自由式摔跤比赛常用技术、摔跤中常用的转动动作、自由式摔跤技术转动分析、自由式摔跤中转动力技术的使用对自由式摔跤技术中的转动力展开以下分析。

自由式摔跤技术中转动力的分析

一、前言 人体各环节的运动都是绕关节轴的转动。人体走、跑、跳等动作是通过环节的转动来完成的。所以,人体各环节的转动是人体运动的基础。 在体育运动中广泛存在着转动。它符合人体运动的科学原理,充分发挥人体潜在的转动力。它根据人体解剖的生理特点,建立在运动生物力学的规律基础之上。 我们在摔跤比赛中经常出现转动方向不对或转动过程中支点没有掌握好、转动的角度不对等一些问题。

地幔对流反转:盆地反转的动力来源

全球中生代与新生代油气盆地在其发育某阶段发生了多期盆地反转,早期的裂陷盆地在反转期被反转盆地叠加与改造,尽管目前对这些盆地反转发育有了共识,但是对于盆地反转产生的机制没有根本解决。以地幔对流反转为视角,尝试对地壳表层盆地反转成因提出解决途径。利用地球深层与表层过程的相互作用原理,推测盆地反转产生的动力机制涉及到地幔对流的反向流动。建立了盆地反转发育的地幔对流反转模型,讨论了地幔对流反转所引起的岩石圈/地壳反向收缩或伸展运动,从而导致盆地收缩或伸展变形。本构想重大意义在于对地幔对流状态、动力及其变化的理解、研究将会对板块反向运动的研究产生深远影响。

齿轮耦合的转子-轴承系统非线性动力特性的研究

在考虑齿轮时变啮合刚度、齿侧间隙、脱齿、挤齿及齿背接触 等因素的情况下，建立了齿轮耦合的转子—滑动轴承系统的多自由度动力学模型。用数值方 法研究了该系统的质量不平衡响应，结果发现，由于齿轮时变啮合刚度的影响，随着转速的 增加，系统动力学响应首先由周期运动向准周期运动变化，当转速超过某一值时，系统的响应将由准周期运动发展为混沌运动；由于混沌运动，转子将沿齿轮中心线方向产生很大的变 形，脱齿、齿背接触及挤齿现象也将发生，可能导致系统产生破坏。

VIBRATION CHARACTERISTIC INVESTIGATION OF COUNTER-ROTATING DUAL-ROTOR IN AERO-ENGINE

Two methods for vibration characteristic investigation of the counter-rotating dual-rotors in an aero-en- gine are put forward. The two methods use DAMP tool on the MSC. NASTRAN platform and develope the re- solving sequence. Vibration characteristics of a turbofan engine are analyzed by using the two methods. Com- pared with results calculated using transfer matrix method and test results, the two methods are valuable and have great potential in practical applications for vibration characteristic investigation of aero-engines with high thrust-weight ratio.

可倾转变形高层救援多旋翼飞行器总体设计

针对城市建设高度立体化、复杂化导致高层火灾救援中常出现的错失黄金救援时间影响救援效率等问题,提出一种可倾转动力的高层救援变形多旋翼飞行器的总体设计,并对其总体性能进行了建模分析。通过计算与选型,得到了满足设计条件的主要部件的型号。验证了该飞行器搭载救援物资和装备完成主动救援等工作的可行性。将其投入到高层救援装备市场,可有效延长受困群众的黄金救援时间,真正意义上提高受困人员的生存率。

Molecular dynamics simulation of relationship between local structure and dynamics during glass transition of Mg_7Zn_3 alloy

The rapid solidification process of Mg7Zn3 alloy was simulated by the molecular dynamics method. The relationship between the local structure and the dynamics during the liquid-glass transition was deeply investigated. It was found that the Mg-centered FK polyhedron and the Zn-centered icosahedron play a critical role in the formation of Mg7Zn3 metallic glass. The self-diffusion coefficients of Mg and Zn atoms deviate from the Arrhenius law near the melting temperature and then satisfy the power law. According to the time correlation functions of mean-square displacement, incoherent intermediate scattering function and non-Gaussian parameter, it was found that the β-relaxation in Mg7Zn3 supercooled liquid becomes more and more evident with decreasing temperature, and the α-relaxation time rapidly increases in the VFT law. Moreover, the smaller Zn atom has a faster relaxation behavior than the Mg atom. Some local atomic structures with short-range order have lower mobility, and they play a critical role in the appearance of cage effect in theβ-relaxation regime. The dynamics deviates from the Arrhenius law just at the temperature as the number of local atomic structures begins to rapidly increase. The dynamic glass transition temperature （Tc） is close to the glass transition point in structure （TgStr）.

PARAMETER OPTIMIZATION OF ELECTRIC POWER STEERING INTEGRATED WITH ACTIVE FRONT STEERING FUNCTION

The dynanaic model of a novel electric power steering（EPS） system integrated with active front steer- ing function and the three-freedom steering model are built. Based on these models, the concepts and the quanti- tative expressions of road feel, sensitivity, and operation stability of the steering are introduced. Then, according to constrained optimization features of multi-variable function, a genetic algorithm is designed. Making the road feel of the steering as optimization objective, and operation stability and sensitivity of the steering as constraints, the system parameters are optimized by the genetic and the coordinate rotation algorithms. Simulation results show that the optimization of the novel EPS system by the genetic algorithm can effectively improve the road feel, thus providing a theoretical basis for the design and optimization of the novel EPS system.

A Study on Vertical Spatial Transfer of Cultivated Land in Yunnan Province from 1986 to 2008

Based upon ArCGIS,the vertical spatial transfer law of cultivated land in Yunnan was studied through referring to three periods of remote sensing data of Land-Use and Land-Cover Change（LUCC） in Yunnan in 1986,1995 and 2000,Digital Elevation Model（DEM） of Yunnan Province and LUCC data in Yunnan from 2000 to 2008.The main factors that promote vertical spatial transfer law of cultivated land were analyzed by using SPSS,and the influence of policies and government acts upon the change of cultivated land was clarified.The findings indicated that for Yunnan cultivated land there is a trend that in the vertical direction steep slope areas and gentle slope areas divert into mid-slope areas.The primary factor influencing the vertical spatial transfer of cultivated land was policies and government acts.Also,the gradient of ground,total population and number of agriculture employed persons were also main factors in influencing the change of cultivated land,whose influence was obviously below policies and government acts.

Formation and evolution characteristics of bcc phase during isothermal relaxation processes of supercooled liquid and amorphous metal Pb

The formation and evolution characteristics of bcc phase during the isothermal relaxation processes for supercooled-liquid and amorphous Pb were investigated by molecular dynamics simulation and cluster-type index method （CTIM）. It is found that during the relaxation process, the formation and evolution of bcc phase are closely dependent on the initial temperature and structure. During the simulation time scale, when the initial temperature is in the range of supercooled liquid region, the bcc phase can be formed and kept a long time; while it is in the range of glassy region, the bcc phase can be formed at first and then partially transformed into hcp phase; when it decreases to the lower one, the hcp and fcc phases can be directly transformed from the glassy structure without undergoing the metastable bcc phase. The Ostwald＇s ＂step rule＂ is impactful during the isothermal relaxation process of the supercooled and glassy Pb, and the metastable bcc phase plays an important role in the precursor of crystallization.

Analysis and Experimental Identification of Torsional Dynamic Characteristics of Hydrodynamic Torque Converter

The subsection linear torsional model of hydrodynamic torque converter was established and further simplified. According to the identification theory, the frequency characteristic was achieved with the Matlab/ Ident toolbox. Then parametric model was established by adopting the subsection linearization method, and the damp value was estimated. The curve and function of damp changing with speed ratio was also established by fitting. In order to validate the identification results, the experimental output was compared with the output of the model in which torque was chosen as input signal and speed as output signal in Matlab/Ident toolbox. It was shown that model output is in good agreement with experimental output.

Impact of anisotropic growth on kinetics of solid-state phase transformation

Based on the statistical analysis of blocking effect arising from anisotropic growth,the anisotropic effect on the kinetics of solid-state transformation was investigated.The result shows that the blocking effect leads to the retardation of transformation and then a regular behavior of varying Avrami exponent.Following previous analytical model,the formulations of Avrami exponent and effective activation energy accounting for blocking effect were obtained.The anisotropic effect on the transformation depends on two factors,non-blocking factor γ and blocking scale k,which directly acts on the dimensionality of growth.The effective activation energy is not affected by the anisotropic effect.The evolution of anisotropic effect with the fraction transformed is taken into account,showing that the anisotropic effect is more severe at the middle stage of transformation.

门窗选型与建筑施工对水密性能的影响

门窗是建筑的外围护结构,其基本功能是挡风遮雨,但由于门窗的选型问题、使用位置问题、外墙结构施工问题、窗户密封条设计问题、安装问题等环节均会造成门窗渗漏,给业主造成损失并且发生法律纠纷。本文从门窗的窗型设计选用、使用位置、外墙结构施工及安装等环节进行了阐述,汇总了与门窗渗水相关的因素与关键点,给门窗的设计施工提供了参考依据。

EFFECT OF UPSTREAM ROTOR ON AERODYNAMIC FORCE OF DOWNSTREAM STATOR BLADES

To study the amplitude and the frequency of the aerodynamic force on stator blades, micro-sensors are embedded on the surface of stator blades of a low-speed single-stage axial compressor rig. The unsteady pressure distribution on stator blades is measured under the conditions of different axial spacing between the rotor and the stator, different rotating speeds and an extensive range of the mass flow. Amplitudes and frequencies of aerodynamic forces are analyzed by the Fourier transform. Experimental results show that under the effect of the rotor wake, the dominant frequencies of pressure fluctuations on stator blades are the rotor blade passing frequency （BPF） and its harmonics. The higher harmonics of the rotor BPF in the fore part of the suction side are more prominent than that in the other parts of the stator blade. Otherwise, fluctuations of the pressure and the aerodynamic force on stator blades vary with the mass flow, the rotating speed and the axial spacing between the rotor and the stator.

农地流转下的我国家庭农场发展途径研究

随着农地流转的加快推进,作为一种重要新型农业生产经营主体的家庭农场,将对提高农业劳动生产率和增加农民收入起到重要作用。在分析我国农地流转动力源的基础上,对家庭农场的优势和面临的挑战进行了探讨,为进一步推动我国家庭农场持续发展,应加强农村土地确权登记,加快土地流转步伐;加大对家庭农场土地流转的支持力度;加强教育培训,培育新型家庭农场经营主体;健全社会养老保障体系,弱化土地社会保障功能;完善社会化服务体系,营造良好发展环境。

COUPLED DYNAMIC CHARACTERISTICS AND CONTROL OF ROTOR-CONICAL MAGNETIC BEARING SYSTEM

The coupled dynamic characteristics of the conical electromagnetic bearing are presented and their definitions are given. On the basis of the analyses of the characteristics, the dynamic model of five degrees of freedom (five-DOF) rotor-conical electromagnetic bearing system is made, and the influence of the coupled characteristics on the system optimal controller is analyzed.