Gravitational-wave versus electromagnetic-wave antennas

Unlike radio waves, gravitational waves have not yet been conclusively detected. However, there is indirect evidence from the slow decay of binary-pulsar systems. The author describes some of the gravitational antenna hardware, and tries to relate it to the more-familiar antennas of radio, radar, and astronomy. Particularly noted is the phenomenon that an electromagnetic antenna readily intercepts the time-varying wave, whereas a gravitational wave readily passes right through its counterpart, with minuscule energy transfer     

以石墨为导电基质的黑孔化新技术

介绍了以石墨作为导电基质,进行印刷电路板孔金属化直接电镀的黑孔新技术,探讨了以石墨分散液在孔壁成膜的过程与导电原理。介绍了黑孔处理的工艺流程,以及黑孔质量与黑孔液稳定性的检测方法。通过孔横截面的金相显微照片确认了通孔与盲孔经过以石墨为导电基质的黑孔液处理后,均能获得完整的电镀铜层。     

Microwave acoustics

During the last few years, generation and propagation of acoustic waves have been extended to frequencies high into the gigacycle region. This paper deals with microwave acoustics, with emphasis on effects and techniques utilized at cryogenic temperatures. The extremely short wavelengths require the use of single crystal propagation media, free from defect scattering, supercooled to reduce wave attenuation from phonon interactions. Interactions of acoustic phonons with other phonons, electrons or holes, and spin waves are possible, with interchanges of energy that can produce attenuation or amplification of acoustic waves. The fundamental characteristics of acoustic wave propagation in crystanine media are discussed, with a review of experimental techniques and results. Microwave acoustic waves in solids and transducers suited to generation and detection are discussed, and a basic analysis of plane wave piezoelectric coupling is presented.     

Will gravity-wave communication be possible? [gravity readgravitational]

Evidence for the existence of gravitational waves is briefly reviewed, and techniques for generating and receiving gravitational waves are considered. It is concluded that the physical limitations encountered and the elusiveness of the waves themselves make their application for communication remote     

Inverse black body radiation at submillimeter wavelengths

The reverse black body radiation problem, involving the determination of the area-temperature distribution of a black body from its measured radiated power spectrum has recently been solved by Bojarski. A simplified result restricted to microwave frequencies has also become available recently. Our approach, which is similar to Bojarski's but much simpler, is restricted to submillimeter waves and/or low temperatures.     

吉林一次暴雨激发平流层重力波的AIRS观测

为了分析中国陆地区域深对流激发平流层重力波的特征,针对2010年7月20日发生在吉林上空的一次暴雨事件,利用Aqua卫星高光谱大气红外探测器（Atmospheric Infrared Sounder, AIRS）的观测数据并结合ERA-interim高空背景场数据和S变换小波分析方法,分析了与暴雨相伴的深对流激发平流层重力波的传播特征,进一步讨论了重力波上传过程对暴雨发展的可能影响。     

Stability of black, gray, and bright nonlinear guided waves in athin film bounded by a self-defocusing medium

Stability of nonlinear guided waves trapped in a thin linear film bounded by an infinite self-defocusing nonlinear medium is investigated. In addition to the trapped black and gray nonlinear guided waves, the existence of a novel class of bright nonlinear guided waves (with nonzero intensity background) is demonstrated. The gray and fundamental bright nonlinear guided waves are found stable whereas the black nonlinear guided waves are unstable to an asymmetric perturbation (but stable to a symmetric perturbation). The instability of the black nonlinear guided waves is shown to develop into various states, including stable gray and bright nonlinear guided waves, depending on initial excitations     

基于像素滤波和中值滤波的深度图像修复方法

针对Kinect相机采集的深度数据一般有噪声和黑 洞现象,直接应用于场景三维重建系统中效果差的问 题,提出了像素滤波器和中值滤波器相结合的Kinect 深度图像修复方法。首先对一帧图片 上的像素进行搜索, 找到像素值为0的点,以该点为中心,利用其邻域内的像素,定义一个两层的滤波器,根据 像素滤波器的原理 对其进行修复,填充深度图片的黑洞;然后采用中值滤波器,在平滑深度图像的同时保留边 缘信息,去除孤立 噪声点。实验结果表明,本文方法去噪的同时也能对黑洞进行修补,与原始深度图像相比, 空洞明显减少,深度图像质量大大提高。     

Modulations of laser signals by water waves observed by a boxcarintegrator

This paper describes a new measurement technique for active remote sensing of water waves using a lidar. To demonstrate this technique, a series of experiments studying interactions of laser pulses with water waves was performed in an NRL wave tank. This technique used a commercially available boxcar integrator to sample IR laser pulses reflected from water waves. These water waves were generated either by artificial winds or a mechanical paddle in the wave tank. The boxcar integrator samples these laser waveforms as a function of windspeeds and paddle frequencies. This paper describes the experimental technique, the measurements, and the data analyses. For wind-generated water waves, results of the data analyses show that lidar-detected laser energies and the lidar-detected water-wave frequencies are functions of windspeeds. For paddle waves, the measurement data show that the laser backscattering cross-section from a water wave is a function of height positions within the water wave. The measurement data successfully demonstrate a boxcar-integrator waveform-sampling technique as an alternative technique to, and possible improvement over, a conventional waveform digitizer. The potential application of this technique in active remote sensing is discussed     

超声波在FPC黑孔化工艺中的应用研究

黑孔化直接电镀可以替换化学沉铜工艺,对传统的PTH是个挑战。超声波的主要原理是超声空化作用,能获得良好的孔清洗效果和灌孔效果。在黑孔工艺流程中使用超声波可以改善镀通孔的质量,提高产品合格率。通过对超声波功率的调整,．使黑孔化直接镀铜工艺得到改善,表明了超声波在黑孔化工艺起了重要作用。     

Acoustic diffraction of light in anisotropic media

The Bragg formalism which describes the diffraction of optical radiation by traveling acoustic waves is generalized to include diffraction in anisotropic media. When the diffracted and incident optical polarizations are different, the Bragg relations require important modification. The correctness of the suggested modifications is confirmed by experiments using optical diffraction from longitudinal and transverse acoustic waves in crystal quartz and in sapphire. A special case of diffraction from longitudinal waves in an anisotropic medium is discussed as a simple example of a collinear parametric interaction.     

引发电控模块短路之PCB孔口发黑原因研究

PCB在使用过程中在经常会出现短路故障,对相关故障电子模块进行分析时发现模块PCB较多孔口存在发黑物质,严重者出现黑色物质连孔,通过测试确认黑色物质具有导电功能。本文通过理论分析及模拟实验论证,确认了黑色物质是引发电子模块故障的根源,同时明确了其产生机理,并提出了针对性的预防措施。     

On the role of absorption in multilayer dielectric mirrors used in laser gravitational antennas

The effect of absorption on different designs of the interferometers of laser gravitational antennas for detection of gravitational waves is analyzed. It is shown that, for small values of absorption, the sensitivity of the Mach-Zehnder interferometer is higher than the sensitivity of the Michelson interferometer. A structure with continuous variation in the refractive index, which serves as Fabry-Perot resonators in the Mach — Zehnder interferometer, is considered.     

Size Reduction of Mushroom-Type EBG Surfaces by Using Edge-Located Vias

Periodic surfaces made of patches with metallized via holes or grounding pins (ldquomushroomsrdquo) have been shown to have bandgaps in their dispersion diagrams, inside which surface waves cannot propagate. These bandgaps are defined in all directions in the surface structure. The purpose of this work is to show how by changing the position of the metallic via of the mushroom from its center to its edge, the bandgap moves towards lower frequencies. This allows an easy structure size reduction which is critical in many applications. Results prove a size reduction of the unit cell size by approximately 20% by only moving the via position. The conclusions have been validated with measurements.     

Improving the speed of convex hull calculations

In certain applications of image analysis (e.g. automatic visual inspection) it is possible to obtain silhouettes of isolated objects. In such situations, it is possible to use the algorithm and hardware discussed in this article. A hardware mechanism is described that is able to select points from a binary image corresponding to local changes in the direction of a black/white edge. This allows the subsequent, software-based, computational work to be reduced by a substantial amount; in the examples cited, the average savings exceeded 80%. The technique can tolerate holes in the silhouette.     

利用砷化镓表面的二次谐波测量ps激光的脉宽

本文报道了利用GaAs晶体表面的二次谐波测量ps激光脉冲宽度的原理、实验方法和结果,并讨论了用半导体表面的二次谐波方法测量fs激光脉宽的可行性.     

Drilling holes in Mars

This paper describes an electric drill that will make the first holes in rocks on Mars. Attached to a robotic arm on the mission's roving vehicle, the Rover Rock Abrasion Tool will bore holes 45 mm in diameter and 5 mm deep in Mars rocks. To make each indentation, Honeybee has been allotted only 32.5 Wh. The drill itself with its diamond bit weighs just 0.7 kg     

Black versus white in heat transfer

The article describes a favorite experiment of the author, which explores the difference between black and white as it applies to radiant energy. It involves placing two quart metal cans of asphalt in an oven. One can is sprayed black, while the other retains its shiny surface. The time taken for each can to reach a target temperature is recorded, and a heating equation derived. The results show that the black sprayed can heats up considerably faster than the shiny one.