一种水下运动目标被动报警的新算法

根据矢量水听器的测向原理和算法，提出了一种目标方位角的变化实现水下运动目标低频高精度的报警方法。该报警系统以水下设施为平台，对靠近设施的运动目标的方位进行跟踪测量，并在目标距离水下设施最近时给出报警信号，以达到有效地避免事故的目的。与传统的利用声级变化报警或主动回波测距报警方法相比，该方法具有低频、作用距离远和高精度的特点。     

Global Convergence Analysis of Algorithms for Finding Feasible Points in Norm-Relaxed MFD

This paper introduces two new algorithms for finding initial feasible points from initial infeasible points for the recently developed norm-relaxed method of feasible directions (MFD). Their global convergence is analyzed. The theoretical results show that both methods are globally convergent; one of them guarantees finding a feasible point in a finite number of steps. These two methods are very convenient to implement in the norm-relaxed MFD. Numerical experiments are carried out to demonstrate their performance on some classical test problems and to compare them with the traditional method of phase I problems. The numerical results show that the methods proposed in this paper are more effective than the method of phase I problems in the norm-relaxed MFD. Hence, they can be used for finding initial feasible points for other MFD algorithms and other nonlinear programming methods.     

The Performances of the Antennas in Active/Passive Compounded Guidance Part I: Broad-Band Antennas and Passive Direction-Finding Schemes

Part one of a two-part paper analyses the performances of the ultra broad-band antennas which are the key components in the broadband passive guidance in details. Two kinds of passive direction-finding schemes which have wide fields of vision are raised and analyzed in this part. Because of the uncertainty of the phase-centers of the antennas, the usual amplitude sun-subtraction monopulse technique can not be used to find the direction of a radiative source in a wide frequency range. A beam-operation network which can be used to form two secant beams from single broad-band spiral antenna is able to applied in the amplitude-monopulse system. An algorithm to eliminate the angle-confusion in the amplitude-phase monopulse direction-finding system is also studied.     

Beam Waveguide Reflector with Integrated Direction-Finding Antenna for In-Situ Alignment

An in-situ alignment system for beam waveguides based on an interferometric direction-finding antenna was investigated numerically and experimentally. The system consists of a reflector with four off-central positioned waveguide couplers in two directions. By nulling the difference of the power signals as well as the mixing signal from each coupler pair, spatial and angular alignments of a beam impinging on the mirror can be performed.In this paper, the characteristics of such a mirror are presented, and the design of a prototype intended for use in an ECH transmission line at LHD is described. Low-power as well as high-power tests at a frequency of 82.7 GHz were carried out, and the results are discussed. The device shows a high performance in agreement with theory.