气体加速度传感器的研制

设计了以气体做敏感质量的气体摆加速度传感器,与传统的固体和液体加速度传感器相比,气体加速度传感器避免了用固体或液体作敏感质量块难以承受强振动、高冲击的缺点。用气体摆原理制作的加速度传感器除了具有抗冲击外还具有响应快、结构简单、价格低廉等优点。     

关于单摆加速度与摆角关系的探究

不同初始摆角的单摆,摆球速度和拉力在最低点达到最大值,在最高点达到最小值.但是,本研究发现:加速度的最值与初始摆角有关,并以41.4°为分界,对于初始摆角大于和小于41.4°有着截然不同的结果.     

单摆在初始偏角为90°时的运动情况分析

单摆在摆角小于5°时的运动可视为简谐振动,偏角较大时的运动可看成是在竖直平面内圆周运动的一部分.本文着重讨论单摆在偏角较大时运动过程中的摆球的速度、加速度、动量以及摆线的拉力的变化情况.     

基于光机集成仿真技术的摆镜特性分析

为考察相关跟踪系统摆镜在静力和动力载荷工况下面形参数是否满足工程需求,基于光机集成仿真技术对相关跟踪摆镜特性进行了分析,得到了在静力和时间历程载荷所对应的三种工况下的面形变化分布和面形表征参数,并对仿真结果的数据可靠性进行了数值角度验证。结果表明,光机集成仿真方法可以有效地消除由动力载荷产生的主动刚体位移,可得到摆镜面形参数和在动力载荷作用下不同时刻的摆镜面型变化,弥补了在实验条件下难以测得由动力载荷作用的面形参数和面形分布情况。当1g加速度载荷在摆镜光轴方向上时,静力载荷对面形的影响起主导作用;当1g加速度载荷不在摆镜光轴方向上时,动力载荷对面形的影响起主导作用。通过光机集成仿真结果对所设计的摆镜在相应工况下的面形进行有效评估,获得了有意义的设计指导数据。     

激光加速度传感器的理论研究

提出了一种新型加速度传感器的设计理论。该传感器设计以角锥棱镜作为惯性摆，利用光学干涉原理，可以实现对运动物体的二维加速度测量。对该传感器进行了系统的理论研究，给出了二维加速度激光传感器设计参量选取的一般规律，并给出了实验的初步结果。     

两种摆运动的视频分析

利用Trakcer视频分析软件,对大角度单摆和圆锥摆的角位移数据进行拟合分析,得到了大角度单摆的准周期性规律,并精确验证了向心加速度公式.     

关于牵连体速度及加速度变化规律的分析

对一道牵连体的高考模拟题展开分析,并推导出两牵连体的速度和加速度表达式,并利 用 Ma t h e ma t i c a模拟出二者随绳子摆角的变化规律     

航天侦察系统中的碳化硅指向摆镜的有限元分析

在航天侦察系统中,由于光学系统的视场角较小,难以满足系统宽覆盖范围的要求,所以往往采用指向摆镜,并绕两轴连续地或间歇地摆动来对地面不同位置的目标进行观测。但是由于空间工作环境会使光学指向摆镜的形状及内部应力发生变化,进而会对其光学特性产生明显的影响,因此对它进行工程分析就显得尤为重要。运用有限元法,对轻量化后的碳化硅指向摆镜在不同加速度条件下的面形和内部应力的变化作了研究和分析,同时对轻量化后的碳化硅指向摆镜在不同的温度场中的面形和内部应力的变化也作了研究和分析,为侦察系统的光学设计和结构设计提供了一些可供参考的数据。     

牛顿第二定律实验器

本仪器系将牛顿第二定律仪器——小车,平台,外加二电磁铁,用一秒摆控制使每秒通电一次,在小车上作出记号,可作下列实验: 一、路程与时间关系, 二、力与加速度关系(第二定律)。验证路程与时间关系时,可将小车放好(如图1),用电磁铁A的衔铁钩住,在砝码盘上放适当重量砝码,     

第七章 机械振动和机械波

第七章机械振动和机械波练习一简谐振动单摆一、判断题１．简谐振动是匀变速运动；（）２．简谐振动加速度的方向总是指向平衡位置，与速度方向无关。（）３．单摆的摆长，就是单摆摆线的长度。（）４．在广州走时准确的摆钟，搬到北京后，摆钟走时将变慢。（）５．两个单...     

On electromagnetic waves by an accelerated charged particle in medium

We have investigated the effects of acceleration of a charged particle on its Cerenkov emission and ionization-losses. We have considered the accelerated motion of a charged particle in an infinite medium with the acceleration parallel to the direction of its motion. We have used the method of Fourier transforms to solve the Maxwell's equations with appropriate current and charge-densities to find electromagnetic fields and hence the force experienced by the incident charge due to its interaction with the medium (dielectric or plasma). The results obtained are general and applicable to any acceleration. In the approximations of ‘small acceleration’ and ‘small interaction time’, we have solved the wave equations and determined electromagnetic potentials. It is found that the acceleration of the charged particle strongly changes both its ionization-loss and Cerenkov emission.     

Motion of a drop driven by substrate vibrations

We report an experimental study of liquid drops moving against gravity, when placed on a vertically vibrating inclined plate, which is partially wet by the drop. Frequency of vibrations ranges from 30 to 200 Hz, and above a threshold in vibration acceleration, drops experience an upward motion. We attribute this surprising motion to the deformations of the drop, as a consequence of an up/down symmetry-breaking induced by the presence of the substrate. We relate the direction of motion to contact angle measurements.     

Dynamics of individuals and swarms with shot noise induced by stochastic food supply

We study the Brownian dynamics of individual particles with energy depot in two dimensions and extend the model to swarms of such particles. We assume that the elements (energy depots) are provided at discrete times with packets of chemical energy which is subsequently converted into acceleration of motion. In contrast to the mechanical white noise which is incorporated in the equations of mechanical motion and has no preferred direction, the energetic noise, as discussed in this study, is directed and it does not reverse the direction of mechanical motion. We characterize the effective noise acting on the particles and show that the stochastic energy supply may be modeled as a shot-noise driven Ornstein-Uhlenbeck process in energy which finally results in fluctuations of the velocity. We study the energy and velocity distributions for different regimes and estimate the crossover time from ballistic to diffusion motion. Further we investigate the dynamics of swarms and find a transition from translational to rotational motion depending on the rate of the shot noise.     

On General Møller Transformation

We give a study on the general Møller transformation and emphatically introduce its differential form. In this paper, a definition of acceleration is given in spacetime language and the inertial reference frame is also settled. With a discussion of thegeodesic equations of motion, the differential form of the general Møller transformation at arbitrary direction is presented.     

Vibration-induced climbing of drops

We report an experimental study of liquid drops moving against gravity, when placed on a vertically vibrating inclined plate, which is partially wetted by the drop. The frequency of vibrations ranges from 30 to 200 Hz, and, above a threshold in vibration acceleration, drops experience an upward motion. We attribute this surprising motion to the deformations of the drop, as a consequence of an up or down symmetry breaking induced by the presence of the substrate. We relate the direction of motion to contact angle measurements. This phenomenon can be used to move a drop along an arbitrary path in a plane, without special surface treatments or localized forcing.     

Irregular array motion and extended integration for the suppression of spatial aliasing in passive sonar

Conventional synthetic aperture processing uses motion of the sonar to increase aperture size and bearing resolution. Two recent papers discussed a different application in which synthetic elements are used to fill in an otherwise sparse passive array. This paper points out that ambiguities persist, even with synthetic elements, in the ideal case of a straight, uniform, sparse line array with constant velocity in the presence of plane wave signals. It is also shown that irregular motion such as acceleration introduces additional information which can be exploited to suppress the ambiguities. The degree of suppression in such an approach is independent of signal direction. If source stability supports extended coherent integration, then the acceleration and integration time required are both modest to achieve interesting levels of suppression. For a less stable source, a modified conventional beamformer is introduced which leverages acceleration over multiple snapshots to suppress the ambiguities. A post-beamformed processing stage involving a nonlinear deconvolution technique such as the CLEAN algorithm can further improve the result. A semi-coherent adaptation of CLEAN is shown to remove the residual ambiguities effectively in the presence of a moderate level of uncorrelated noise.     

Experimental determination of the free-fall acceleration of a relativistic charged particle. I. Relativistic relation between the observed velocity and acceleration of the free-fall

This paper discusses the relativistic relation between the observed velocity and acceleration of free fall, which was obtained previously by the author. The contradiction is shown between this relation and the experimental results on the equivalence of gravitational and inertial mass. For the measurement of the free-fall acceleration of a relativistic charged particle, it is proposed that use be made of a uniform magnetic field limiting the region of motion of the particle, which is performing a free fall along the direction of the field.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 25–28, July, 1979.     

Controlled collective acceleration of electron-ion bunches

The fundamental possibility of a new method for controlled collective ion acceleration by electron bunches of high-current relativistic picosecond beams has been proved. Dense relativistically rotating electron bunches are formed using a cusp magnetic system by their capture in a special magnetic trap. An electron bunch is filled with ions when it interacts with a preliminarily prepared plasma bunch with a certain density. Then, the effective potential well of the magnetic trap is stepwise shifted synchronously with the motion of ions by means of a system of turns with controlled currents. This ensures the displacement and confinement of electrons in the direction of acceleration. The shift of the center of the well at each step is chosen such that ions are in the region of acceleration by a high self electric field of the electron bunch. In contrast to the known methods for collective acceleration, the proposed method makes it possible to avoid the mismatch of the electron and ion components of bunches, disruption of the acceleration of ions, and development of numerous instabilities, because the duration of the acceleration cycle is in the nanosecond range.     

Escape into vacuum of fast electrons generated by oblique incidence of an ultrashort, high-power laser pulse on a solid target

The possibility that fast electrons can escape in a direction close to the trajectory of a reflected ultrashort laser pulse at extremely high laser radiation fluxes is examined analytically and numerically. Analytic estimates are made of the feasibility of forming electron bursts in the plasma and of their subsequent motion. The self-consistent, collisionless motion of a plasma acted on by specified incident and reflected ultrashort laser pulses is modeled in two dimensions by the particle-in-cell method. It is shown that a substantial number of electrons located in the subcritical region are gathered into bunches by the resultant forces and escape to the vacuum in a direction different from the normal to the target surface within a narrow range of solid angles. This demonstrates the feasibility of laser acceleration of an electron burst during reflection of an ultrashort laser pulse from a solid target. Zh. éksp. Teor. Fiz. 116, 1184–1197 (October 1999)     

An electrodynamic vacuum arc ion acceleration mechanism based onAmpere's force law

It is known that the motion of cathode spots is of electromagnetic origin, thus leading to methods of steering the spots by controlling the direction of the self and applied magnetic fields. The author discusses the ion flux from the cathode spot, focusing on two well-recognized features of this flux that are difficult to explain. These are the anomalously high energies of the ions, and their highly anisotropic spatial distribution. An electrodynamic acceleration mechanism, based on Ampere's force law, is proposed as an explanation of these phenomena. The theory is shown to be consistent with existing particle production models, and also provides a consistent solution to macroparticle emission and retrograde motion