I will show the buckling analysis of a beam by nonlinear beam element of total lagrangian formulation. The beam element has not only the geometric stiffness of rotation but also the geometric stiffness of large strain. As the results of the analysis, it will be shown that the buckling loads of the beam element are less than the theoretical buckling loads.
This paper presents a study on near circular orbits around asteroids, whose purpose is to make optical observations of asteroids globally with high resolution. All the asteroids, whose sizes are below 100km, are objects. At first, the feasible region of the frozen orbit was studied. There exist two kinds of the frozen orbits. One is the orbit in the orbital plane of the asteroid and was found not to be adequate for observation with high resolution because of the large altitude. The other is the solar plane-of-sky orbit whose orbit normal corresponds to the solar or anti-solar direction, and was found to be adequate for asteroids whose radii are below 2 or 3km. Maintenance of polar orbits, which are adequate for global observations of asteroids and have the merit that effects of the oblateness disappear, was studied by numerical integrations. It turned out Cp/(Cs*ellmlt) can be used to roughly judge the necessity of maintenance maneuvers.
A bubbling liquid jet was ejected normal to a highspeed airstream to control a spatial distribution of the ejected liquid under an airstream velocity of 70m/s and a constant injection pressure. And spray shapes were obtained by scattered-light photographs with a long exposure time and the liquid mass flow rate per unit area were measured by the mass sampling technique. The height of the maximum liquid mass flow rate per unit area in the spray hardly changed, when the ratio of the mass flow rate of the ejected liquid to standard mass flow rate decreases from 100% (without gas) to 39% increasing the gas/liquid rate. However, with decreasing the ratio, maximum mass flow rate per unit area decreased and the width of vertical and horizontal distribution of the liquid mass flow rate per unit area increased.
A Gust Alleviation System for a helicopter was analyzed by using the linear optimal control theory. In applying this theory, various feedback parameters and weighting functions were selected to investigate the flying qualities of a helicopter. The time histories of the augmented helicopter were investigated based on military specifications. Feedbacks of the forward and vertical speed as well as attitude angles and angular velocities were analyzed to have strong effects to stabilize the helicopter.
There still remain many problems to be solved for conventional adaptive control theory to be applied to a real plant. Some of them are restrictive conditions imposed on the plant, low robustness and poor transient properties. To overcome these problems, we present a new design method of adaptive controllers that are robust to plant noise and uncertainties and have a good transient property. We first propose an algorithm to evaluate and reduce the parameter region in which the transfer function of a real plant exists. According to these plant informations, we can judge how closely the identification is made towards real parameters and whether it is better to continue identification or to execute some control strategy. Stabilizability of the plant is determined by one Riccati equation so that the plant can be stabilized by a quadratic stabilization controller. Some numerical examples together with application to a flight controller design are given to illustrate and substantiate the effectiveness of the proposed method.
Disturbance which most effectively causes the vibration of a dynamical system is defined as “the worst disturbance” and is formulated theoretically by using H∞ control theory in the part 1 of the paper. Objective of the present study is to verify experimentally the characteristics of the worst disturbance on flexible structures obtained numerically in the forgoing paper. Flexible structures are modeled by a Euler-Bernoulli beam and hardware experiment is developed in this paper to verify the validity of the numerical simulation. The experimental apparatus consists of a free-free flexible aluminum beam suspended at two points, non contacting electro-dynamic force actuator and sensors employed with an accelerometer and strain gages. Good agreement is obtained between the result of numerical simulation and the experimental result.