A design of precision linear z-transverse antenna positioner

An antenna positioner is essential device in avionics as a testing instrument. It must be able to move the antenna under test (AUT) to the required position precisely and accurately. This research focuses on the design of precision linear z-traverse antenna positioner. It comprises designs of mechanical, electrical and control system. Besides, knowledge on software design is also of paramount important because the designed instrument run by own developed control algorithm. It is a positioner powered by a DC motor as an actuator which is equipped by a user friendly graphical user interface (GUI) written uniquely featured with several distinct and systematic operating modes and flexible data display. PID (Proportional, Integral and Derivative) controller embedded in GUI is also capable to move AUT to the target in shortest time with no or minimum overshoot and steady state error. In this research, PID controller was tuned to suit the application with the aid of MATLAB® simulation. The system was then calibrated. Based on calibrated data, it was then optimized to yield more accurate result by mean of correction through software compensation. The result was then analyzed and discussed. A very precise instrument with standard deviation m µ s 94 . 8 = was successfully designed. It was designed to be used in two ways with accuracy of approximately m µ 50 ± or 29ppm for high accuracy usage and approximately m µ 300 ± or 176ppm for lower accuracy usage. As a consequence, procedures of design and developing a positioner both theoretically and practically were acquired

Re-examining Symmetry of Shocks for East Asia: Results Using a VAR with Sign Restrictions

I revisit the hotly debated topic regarding the possibility of introducing a common currency for East Asia from the point of view of shock symmetry. I first point out a serious problem of the existing studies which use the VAR method with long-run restrictions developed by Blanchard and Quah (1989) in that the signs of the impulse response functions to the same structural shock are not necessarily consistent across the countries. This means that the high (low) correlations of structural shocks do not necessarily imply low (high) costs of a common currency area. To overcome this problem, I apply the VAR method with sign restrictions developed by Uhlig (2005). I used the AD-AS model to impose sign restrictions on the responses of GDP and CPI to demand and supply shocks. One main finding is that demand shocks are significantly positively correlated among almost all East Asian countries. But overall, East Asia as a whole is not suitable for a common currency because correlations of supply shocks are low.Structural VAR, Long run restriction, Sign restriction, Symmetry of Shocks, Common Currency, East Asia

The complex Jacobi iterative method for non-paraxial beam propagation in nonlinear optical waveguides

The recently introduced beam propagation method using complex Jacobi iteration adapted for modeling of non-paraxial beam propagation in nonlinear optical waveguides is presented in this paper. The beam propagation equation is based on our recently proposed modified Pad,(1,1) approximant operator. The resulting approach is very efficient and well-suited for large structures with long propagation paths

Exterior sphere condition and time optimal control for differential inclusions

The minimum time function $T(\cdot)$ of smooth control systems is known to be locally semiconcave provided Petrov's controllability condition is satisfied. Moreover, such a regularity holds up to the boundary of the target under an inner ball assumption. We generalize this analysis to differential inclusions, replacing the above hypotheses with the continuity of $T(\cdot)$ near the target, and an inner ball property for the multifunction associated with the dynamics. In such a weakened set-up, we prove that the hypograph of $T(\cdot)$ satisfies, locally, an exterior sphere condition. As is well-known, this geometric property ensures most of the regularity results that hold for semiconcave functions, without assuming $T(\cdot)$ to be Lipschitz

On the Burgers-Poisson Equation

In this paper, we prove the existence and uniqueness of weak entropy solutions to the Burgers-Poisson equation for initial data in L^1(R). Additional an Oleinik type estimate is established and some criteria on local smoothness and wave breaking for weak entropy solutions are provided.Comment: 22 page