用MATLAB软件分析下滑信标天线阵辐射场形

本文从镜像天线的基本原理出发，深入分析下滑天线信标辐射场形的形成，以此为基础编写出在MATLAB软件运行环境下的程序，并从天线离地高度、馈电信号角度和幅度变化三个方面，用MATLAB软件绘制相对应的场形图，进而分析其辐射场型的相应变化。

RANDOM TERRAIN MODEL

In order to slove a realistic test problem of TF/TA algorithm, it is necessary to make a discrete terrain model. The model has adjustable roughness parameters so as to test the optimization procedure for different types of terrain. In this paper, an algorithm to generate random terrain data is given.

中波八塔天线匹配网络对偏向角度的影响及处理方法

本文通过中波八塔天线理论计算、仿真和实际调试,简述了中波八塔天线的调配中出现的问题,即匹配网络对天线的偏向角度的影响。作者通过对部分移向网络的修正,使前向场强达的场形图达到正常范围,解决了匹配网络对偏向角度的影响。

调频单偶极子垂直极化天线的分析与运用

本文详细介绍了一种调频单偶极子垂直极化天线,阐述了其结构和工作原理,并通过计算机仿真计算分析了天线的阻抗特性、增益特性和方向图,同时阐述了天线在实际使用过程中受到的影响和使用注意事项,说明了运用计算机仿真辅助设计在广播电视覆盖规划设计过程中的重要性。

Accelerating f inite difference wavef ield-continuation depth migration by GPU

The most popular hardware used for parallel depth migration is the PC-Cluster but its application is limited due to large space occupation and high power consumption. In this paper, we introduce a new hardware architecture, based on which the finite difference （FD） wavefield-continuation depth migration can be conducted using the Graphics Processing Unit （GPU） as a CPU coprocessor. We demonstrate the program module and three key optimization steps for implementing FD depth migration： memory, thread structure, and instruction optimizations and consider evaluation methods for the amount of optimization. 2D and 3D models are used to test depth migration on the GPU. The tested results show that the depth migration computational efficiency greatly increased using the general-purpose GPU, increasing by at least 25 times compared to the AMD 2.5 GHz CPU.

High-resolution remote sensing image-based extensive deformation-induced landslide displacement field monitoring method

Landslide is one of the multitudinous serious geological hazards. The key to its control and reduction lies on dynamic monitoring and early warning. The article points out the insufficiency of traditional measuring means applied for large-scale landslide monitoring and proposes the method for extensive landslide displacement field monitoring using high- resolution remote images. Matching of cognominal points is realized by using the invariant features of SIFT algorithm in image translation, rotation, zooming, and affine transformation, and through recognition and comparison of characteristics of high-resolution images in different landsliding periods. Following that, landslide displacement vector field can be made known by measuring the distances and directions between cognominal points. As evidenced by field application of the method for landslide monitoring at West Open Mine in Fushun city of China, the method has the attraction of being able to make areal measurement through satellite observation and capable of obtaining at the same time the information of large- area intensive displacement field, for facilitating automatic delimitation of extent of landslide displacement vector field and sliding mass. This can serve as a basis for making analysis of laws governing occurrence of landslide and adoption of countermeasures.

True Time Delay Scheme for X-band Phased Array Radar

The system of a true-time delay line for X-band and 8-unit phased array antennas is introduced. Changing the length of a chirp grating with piezotranslator(PZT), the variable delay is obtained. The scheme is applied to X-band phased array radar whose searching data rate is 56/s. It is simulated that the beam squinting is influenced by the error of real time delay. The relation between the beamforming mode and its modifying volt is discussed.

UNIFORM CONVERGENCY FOR WEIGHTED PERIODOGRAM OF STATIONARY LINEAR RANDOM FIELDS

Let {Xn; n ∈ N2} be a two dimensionally indexed linear stationary random field generated by a 1/4 martingale difference white noise. The logarithm uniform convergency resulte for the weighted periodogram of is proved.

GPU-accelerated phase field simulation of directional solidification

The phase field simulation has been actively studied as a powerful method to investigate the microstructural evolution during the solidification.However,it is a great challenge to perform the phase field simulation in large length and time scale.The developed graphics processing unit(GPU)calculation is used in the phase filed simulation,greatly accelerating the calculation efficiency.The results show that the computation with GPU is about 36 times faster than that with a single Central Processing Unit(CPU)core.It provides the feasibility of the GPU-accelerated phase field simulation on a desktop computer.The GPU-accelerated strategy will bring a new opportunity to the application of phase field simulation.

Earthquake deformation field characteristics associated with the 2010 Yushu M_s7.1 earthquake

The spatial distribution and characterization of a heavily damaged area can be determined by studying surface ruptures of seismogenic faults.If the distribution of surface ruptures can be obtained shortly after they occur,then areas heavily damaged by an earthquake can be readily identified.The information can then be used as a guide for earthquake relief programs.In this paper,an intensity offset-tracking method applied to an ALOS PALSAR image is used to map the Yushu earthquake rupture and to identify the faults activated by the earthquake.Azimuthal displacement analysis indicates that the surface rupture is about 55 km long,running from the epicenter to the southeast,trending N310°W,with a relative displacement of～1 m characterized by sinistral slip.The result of range displacement observations indicates that the north wall of the fault is dominated by decreases(i.e.,uplift in line of sight observations) ,whereas in the south wall of the fault,the range displacement is dominated by increases(drops in line of sight observations) .Given the position from which the images were recorded,this means that the north wall moves westward,and the south wall move eastward,i.e.,left-lateral slip motion across the fault.Finally,an earthquake disaster assessment using computer-assisted image analysis software shows that buildings near the fault rupture have been destroyed most heavily;therefore,the shape of the heavily damage belt is controlled partially by the fault rupture's geometry and the damage degree relates to the magnitude of displacement field.

Formation mechanism of subtrenches on cone-shaped patterned sapphire substrate

In this paper, the cone-shaped patterned sapphire substrates (PSS) were etched by an inductively couple plasma with BCl 3 as the reacting gas. The influence of the operating pressure and the RF bias power on subtrenches of the cone-shaped PSS and the formation mechanism of subtrenches were investigated. The profiles of patterns were characterized by FESEM (field emission scanning electron microscope). It showed that the subtrench size varied with the operating pressure and the RF bias power. As the operating pressure increased from 0.2 Pa to 0.9 Pa, the subtrenches changed from narrow and deep to wide and shallow; then to narrower and shallower. When the RF bias power varied from 200 W to 600 W, the subtrenches gradually became noticeable. The FESEM results also indicated that the subtrenches were formed due to the ion scattering effect which was caused by tapered sidewalls and charges accumulation. It is discovered that the scattering effect is closely related with the operating pressure and RF bias power.

Fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse quasicrystals

We report a numerical method to analyze the fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse (2-D TM) structures. The far-field diffraction patterns of the 2-D TM structures can be obtained by the numerical method, and they have a good agreement with the experimental ones. The analysis shows that the fractal characteristics of far-field diffraction patterns for the 2-D TM structures are determined by the inflation rule, which have potential applications in the design of optical diffraction devices.

Investigation on 3D flow field induced by a plasma actuator with serrated electrode

This paper presents an experimental investigation on flow field induced by a dielectric barrier discharge(DBD) plasma actuator with serrated electrodes in still air to further improve its flow control effectiveness. For comparison, the actuator with widely used linear electrodes was also studied. Experiments were carried out using 2D particle image velocimetry. Particular attention was given to the flow topology, discharge phenomenon, and vortex formation mechanism. Results showed that a 2D wall jet was induced by the linear actuators, whereas the plasma actuators with serrated electrode introduced a series of streamwise vorticities, which might benefit flow control(e.g., enhancing the momentum transport in the separated boundary flow). In addition, the mechanism of 3D flow topology induced by the serrated DBD actuator was analyzed in detail.