3 mm波段二次谐波渐变复合腔回旋管的非线性模拟

 利用含电流的传输线方程,并在考虑多模注-波互作用及多模耦合的情况下,利用自主开发的多模高次谐波渐变结构复合腔回旋管的注-波互作用数值模拟软件,对3 mm波段二次谐波渐变复合腔回旋管进行了自洽非线性模拟,分析了H₀₂-H₀₃模式对下磁场系数、电流、电子注速度比对注-波互作用效率的影响。计算结果表明,在合适的腔体结构尺寸下,以及合适的磁场系数、电流、速度比下,注-波互作用效率可达27％。     

Characteristics of rain induced attenuation and phase shift at cm and mm waves using a tropical raindrop size distribution model

The tropical raindrop size distribution model developed by Ajayi and Olsen has been employed to study some characteristics of rain induced attenuation and phase shift for a tropical location for spherical, oblate spheroidal and Pruppacher-Pitter drop shapes. Parameters such as the a and b values for the power law relation between the specific attenuation and rainfall rate as well as differential attenuation and phase shift and their normalized values, were computed. A single power law between the specific phase shift and the rain rate was found to be adequate for vertical polarization, whilst a two-segment power law fitting is required for horizontal polarization between 1GHz and about 100GHz. The results were compared in many cases with those obtained with the Laws and Parsons drop size distribution, currently adopted by the CCIR for scattering applications.     

Comparison of soil strength measurements of agricultural soils in Nebraska

In 2014 the University of Nebraska, Lincoln (UNL) was engaged in field testing program to investigate a soil moisture mapping system as a crop management tool. In conjunction with this work, the US Army Engineer Research and Development Center, Cold Regions Research and Engineering Laboratory (ERDC-CRREL) deployed a team to perform soil characterization and strength measurements at three agricultural test sites. The primary objective was an investigation of the Lightweight Deflectometer (LWD) as a soil surface strength tool for the purposes of assessing bearing capacity of soft soils. The LWD measurements were performed with those from more “standard” tests, i.e. the Dynamic Cone Penetrometer, Cone Penetrometer, and Clegg Impact Hammer to determine if the LWD produced results that compared with these methods. The strength test data were also used to calculate California Bearing Ratio (CBR) values using existing equations in order to see if the different test methods produced similar CBR values that could in turn be used to predict the bearing capacity of the sites. The secondary objective was to compare the strength data with the corresponding soil water content data taken by UNL to determine if soil moisture was an indicator of soil strength.     

基于物体特征有效提取和离散点三维重建的3D扫描系统原型研究

针对3D扫描技术的近期发展情况,以及市场关于被摄物体特征有效提取的迫切需求,通过系统的对照相机和投影仪测量的方法与计算,利用离散点三维重建算法、标准化算法详细分析了,作为3D扫描原型系统的关键技术,并深入的对三维坐标重复演算的过程,进行了实践研究与计算,论证了基于投影光编码技术的3D扫描仪原型系统,在物体特征有效提取和离散点三维重建中完全可以高效应用;同时,使用焦距标准化运算、逆向倾角变形运算、逆向扭曲变形运算三种方法,综合论述了物体特征有效提取和离散点三维重建过程的相关内容,测试了原型系统对真实文物的扫描情况,展开了该原型系统可应用于不同材料,不同种类物体的扫描,并能有效的进行数字化物体特征识别的研究结论。     

The transmission performance of the single sideband optical millimeter-wave with BPSK signal in the duplex radio-over-fiber link

This paper has investigated the transmission performance of the single sideband (SSB) optical millimeter (mm)-wave with signal carried by the sideband in BPSK format in duplex radio-over-fiber (RoF) system theoretically and numerically. The SSB optical mm-wave signal is generated by a LiNbO₃ Mach–Zehnder modulator and there exists an optimal modulation index to generate the SSB optical mm-wave with a maximal RF photocurrent. The SSB optical mm-wave is much suitable for the duplex ROF link with the uplink lightwave recovered from the downlink because the optical carrier carries no signal. In such a duplex RoF link, although there are the spurs on the optical carrier, they have little influence on the downlink and the uplink signal even if the modulation index is large.     

A stable submillimeter laser local oscillator for heterodyne radiometry and spectroscopy

A submillimeter laser with off-axis pump beam injection is described. This design concept achieves complete isolation of the pump laser with respect to the pump radiation reflected from the smm resonator. Active line independent stabilization of the pump laser is obtained by the use of an external tunable etalon as a frequency reference. The smm output power is constant to within 4% over periods of hours. Mean frequency drifts of less than 2 parts in 10⁸ per minute were measured by mixing with very high harmonics of an X-band synthesizer in a planar Schottky diode.Supported in part by NSF     

Data processing pipelines for comprehensive profiling of proteomics samples by label-free LC-MS for biomarker discovery

Label-free quantitative LC-MS profiling of complex body fluids has become an important analytical tool for biomarker and biological knowledge discovery in the past decade. Accurate processing, statistical analysis and validation of acquired data diversified by the different types of mass spectrometers, mass spectrometer parameter settings and applied sample preparation steps are essential to answer complex life science research questions and understand the molecular mechanism of disease onset and developments. This review provides insight into the main modules of label-free data processing pipelines with statistical analysis and validation and discusses recent developments. Special emphasis is devoted to quality control methods, performance assessment of complete workflows and algorithms of individual modules. Finally, the review discusses the current state and trends in high throughput data processing and analysis solutions for users with little bioinformatics knowledge.     

A novel approach for simultaneous millimeter wave generation and high bit rate data transmission for Radio over Fiber (RoF) systems

We propose a novel method for simultaneous transmission of OC-192 (9.95328 Gbps) digital data and 60 GHz RF generation in a Standard Single Mode Fiber (SSMF) link utilizing Stimulated Brillouin Scattering (SBS). The system comprises of a 1550 nm DFB Laser diode, Mach Zehnder modulator (MZM), 50 km SSMF and Optical receiver. The receiver includes laser diode for optical pump, a regenerator for data retrieval and a RF bandpass filter for RF generation. This system requires minimum number of RF and optical components for the generation of 60 GHz RF. The remotely generated 60 GHz RF signal may be used for wireless transmission of data. The entire link is simulated in Optisystem software to analyze the system performance.