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Implementation of an OFDM underwater acoustic communication system on an underwater vehicle with multiprocessor structure


Experimental Research on Friction of Vehicle Tire Rubber


The prediction technology study of fatigue life for key parts of a tracked vehicle's suspension system


In allusion to fatigue life of a tracked vehicle torsion bar, a virtual prototype model of the tracked vehicle suspension system including a flexible torsion bar was built based on dynamic simulation softwareADAMS.


The finite element analysis of the vehicle frame was made and the result satisfied the requirements.

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 In this paper, the author analyses one class of self adaptive autopilot's control loops and evaluates the constitution of its main control and adaptive control loops, the dynamic characteristics and the method for parameter selection of these loops. The paper consists of four parts: 1. Criteria for adaptive performance and method for adaption;2. Constitution of model and inner loop and its capability of adaption;3. Constitution of selfadaptive loop and its dynamic response;4. Interference between inner and... In this paper, the author analyses one class of self adaptive autopilot's control loops and evaluates the constitution of its main control and adaptive control loops, the dynamic characteristics and the method for parameter selection of these loops. The paper consists of four parts: 1. Criteria for adaptive performance and method for adaption;2. Constitution of model and inner loop and its capability of adaption;3. Constitution of selfadaptive loop and its dynamic response;4. Interference between inner and adaptive loops.The problems analysed in detail are: the types of model in conection with inner loop, the selection of model's types and parameters, the rule and method of inner loop constitution,the practical construction of model and inner loop,the measurement of adaptive loop, the basic characteristics of ideal adaptive loop, the transfer block diagram of adaptive loop and its characteristics, the compensation of timevariable block and loop parameter selection problem.In the final portion of this paper, the application of this class of control loops and the passibility of its practical realization on vehicles are also noted.  本文将主要分析一种类型自适应自动驾驶仪迴路,探讨其主迴路和适应迴路的构成,迴路的动态特性,以及参数选择的方法。 全文将从:适应性能标准及自适应方法,模型及内迴路的构成及共适应能力、自适应迴路的构成及其动态响应、内迴路和自适应迴路之间的相互影响四个方面进行叙述。 着重地分析了模型和内迴路结合的结构形式,模型型式和参数的选择、内迴路构成的原则和方法、模型和内迴路的具体结构、以及适应迴路的测量方法、理想适应迴路的的基本特性、适应迴路的结构图及共特点、适应迴路时变环节的补偿及迴路参数选择等问题。 在文章最后,还指出了这种迴路的适用场合,目前条件下在飞行器上具体应用的可能性。  The purpose of this investigation is to study the possibility and condition for a lunar probe to hit or to fly over, at close range, any given region on the surface of the moon. We limit the ballistic speed of the vehicle to 11.2 km/sec and require that the height at the last burn out point should be about a few hundred kilometres. Six definite regions on the surface of the moon are considered as the objectives of these flights. Four regions lie on the great circle where the orbital plane of the moon cuts... The purpose of this investigation is to study the possibility and condition for a lunar probe to hit or to fly over, at close range, any given region on the surface of the moon. We limit the ballistic speed of the vehicle to 11.2 km/sec and require that the height at the last burn out point should be about a few hundred kilometres. Six definite regions on the surface of the moon are considered as the objectives of these flights. Four regions lie on the great circle where the orbital plane of the moon cuts the lunar surface. They are designated as the "near", "remote", "east", and "west" points. For these points, only trajectories in the orbital plane of the moon have been considered. The other two regions, namely, the poles of the aforesaid great circle, are called the "north" and "south" points respectively. In the preliminary survey of the possible trajectories, the approximate method of assuming the earthmoon space as divided into two by a sphere of action of radius 66000 km around the moon has been employed. The trajectory may then be considered to consist of several sections, each one of which is determined by the laws of twobody problem. From considerations on the permissible angular momentum of the orbit, it has been possible to derive limiting values for the velocity of hitting and the angle of incidence in the case of impact trajectories. For reconnaissance trajectories, we try to find out the allowable perilunar distance and velocity as well as how close may the perilunar point of the trajectory be brought to the surface of the moon. From preliminary investigation by the approximate method of sphere of action, we have come to the following conclusions: A. For impact trajectories: 1) To hit either the near or the remote point, the vehicle must be approaching the moon from the east side. With velocity of impact somewhere in the range 160—180km/min, the probe may hit these points at an angle of incidence of 30° or greater. 2) Vertical impact is possible only at the east point with the velocity of hitting at slightly less than 160 km/min. 3) The west point may be hit by a lunar probe, but only at grazing incidence. 4) The trajectories for hitting the north and the south points could be mirror images of each other. These points may be hit at an angle of incidence of about 60°, at a speed of less than 160 km/min. B. For reconnaissance trajectories: 1) Over the near and the remote points, there is a whole series of symmetrical orbits in which the vehicle would be sure to return to the neighbourhood of the earth. When the perilunar velocity is about 100 km/min, the distance of close approach to the centre of the moon may be no more than 5000 km. We can make the trajectory come in contact with the surface of the moon, if we allow the perilunar velocity to be increased to 160 km/min. 2) With perilunar distance over 30000 km, it is possible for the vehicle to fly horizontally over the east point of the moon. Such reconnaissance flight is possible over the west point, but the vehicle has to be so low that the orbit becomes identical with the impact trajectory grazing the west point. 3) When the perilunar point of the orbit may be permitted to deviate about 45° from the zenith of the east or the west point, we can still have reconnaissance trajectories that will bring the vehicle back to the neighbourhood of the earth. 4) When we consider only trajectories whose motion inside the sphere of action is in a plane perpendicular to the earthmoon direction, we could have symmetrical orbits with horizontal flight over the north or the south point at a distance of about 24000 km from the centre of the moon. With permissible values at the moon for different definite points, the path of the vehicle is traced backward in time to verify if it did pass by the vicinity of the earth with reasonable speed. If so, the position and velocity of the vehicle near the earth are taken as the initial values at the last burn out point, and the impact or reconnaissance trajectory is computed once again. In such computations the attractions of both the moon and the earth are taken into account by the method of numerical integration. The trajectories thus obtained are listed in Tables 5, 6, and 7.  在月球表面上考虑了六个定点,它们是自道面内的近、远、东、西四点和此外的南北两点。为了要找到可以实现用火箭击中和航测这六点的轨道,我们以在月面定点上可以容许的初值为轨道出发点,倒推出火箭在地球附近时的位置和速度。月面定点上的初值是依据火箭大约在地面上200公里高空以第二宇宙速度发射的假定选取的。所用方法是按作用范围和简单的角动量和能量守恒的原理来考虑的。计算结果表明,火箭从地面上以通常的高度和速度发射能够击中这六个定点:东点可以垂直击中,西点只能切向击中。航测这六个定点,都可以找到有去有回的轨道,航测远、近、南、北四点还可以有对称的轨道。航测远、近点可以和月面接近到任意距离,航测其他各点,距离便要远些,约为二、三万公里。  On the basis of high current density zinc air cells reported in our last papers[1],further improvement of air electrode technology has been made and further increase of current densities has been achieved. In May of this year, a zinc air cell system of 19 volts 800 amperes was assembled from two parallel connected 19 volts 400 amperes batteries and under the condition of forced air supply, starting tests of a certain heavy vehicle have been made. At the same time, two units of 24 volts 50 amperes zinc... On the basis of high current density zinc air cells reported in our last papers[1],further improvement of air electrode technology has been made and further increase of current densities has been achieved. In May of this year, a zinc air cell system of 19 volts 800 amperes was assembled from two parallel connected 19 volts 400 amperes batteries and under the condition of forced air supply, starting tests of a certain heavy vehicle have been made. At the same time, two units of 24 volts 50 amperes zinc air cell system were also assembled, and two tests has been made on a light motor cycle with electrical motor unit. In this paper, improvements on air electrode technology and results of these testing runs are reported in details.  本组在业已报告的高电流密度锌氧一次电池组［１］的基础上，改进了空气极的制作工 艺，进一步提高了电流密度。在今年五月研制、组装了１９伏８００安的锌空气电池组（由 两个１９伏４００安的电池组并联），在强迫通风的情况下，对某种车辆进行了起动试验。 同时，还组装了２４伏５０安的锌空气电池组两套，在装有电动机的轻型摩托车上进行了 两次行车试验。本文叙述空气极制作工艺的改进，和此次试验的结果。   << 更多相关文摘 
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