射频辉光放电氩等离子体诊断分析

为了获得等离子体抛光实验平台中氩等离子体的参数,利用Langmuir单探针与发射光谱法对其进行诊断分析,根据Langmuir探针原理计算了氩等离子体的电子温度与电子密度,采用双谱线相对强度法估算了氩等离子体温度及电子密度.实验结果表明：当射频电源功率在40～120 W时,电子温度随射频电源功率增加而增加,电子温度范围为2.41～5.03eV,等离子体温度随射频电源功率变化不大;两种方法测得的电子密度存在偏差,其随射频电源功率变化的趋势是一致的.     

The state-of-the-art of the China Seismo-Electromagnetic Satellite mission

The China Seismo-Electromagnetic Satellite (CSES) mission was proposed in 2003 and approved in 2013 after ten years’ scientific and engineering demonstrations. To meet the requirement of scientific objectives, the satellite is designed to be in a sunsynchronous orbit with an altitude of 507 km and descending node time of 14:00 LT. The CSES satellite carries 8 instruments, including search-coil magnetometer (SCM), electric field detector (EFD), high precision magnetometer (HPM), GNSS occultation receiver (GOR), plasma analyzer package (PAP), langmuir probe (LAP), high energetic particle package (HEPP) and detector (HEPD), and tri-band beacon (TBB), among which HEPD is provided by Italian Space Agency. The CSES satellite was launched successfully on February 2, 2018, and is planned to operate for 5 years. The CSES mission is the first satellite in China to measure geophysical fields, which will have a lot of application prospects in the study of seismology, geophysics, space sciences, and so on.     

Fast Diagnosis of Transient Plasma by Langmuir Probe

A method for the fast measurement of electron temperature and density with temporal resolution in transient plasma has been implemented by Langmuir probe. The diagnostic system consists of a single Lang- muir probe driven by a high frequency sinusoidal voltage. The current and voltage spectrum on the probe were detected synchronously by an oscilloscope with sampling rate being at least 5 times higher than the frequency of sweep voltage. The system has been used to diagnose the transient plasma generated by hypervelocity-impact of LY12 aluminum projectile into LY12 aluminum target.     

同轴配对电子回旋共振放电产生的等离子体磁场约束的影响

运用朗缪尔探针诊断技术对同轴配对电子回旋共振产生等离子体磁场约束的影响进行了研究。在磁镜约束条件下,电子回旋共振源轴线附近等离子体的密度非常高,但是随着径向距离的增加等离子体的密度会迅速下降;而在会切磁场约束条件下,离子体的密度相对较低却分布均匀。这种趋势与电子温度和等离子体电势的情形类似,并且这种特性可应用于各种材料加工以满足不同的需求。     

在高ECR 等离子体密度下沉积高质量氮化镓薄膜

目的　研究在电子回旋共振等离子体辅助法生长ＧａＮ 时的离子密度对其质量的影响．方法　用朗缪尔探针测量离子密度,用Ｘ 射线双晶衍射及霍尔测量分析ＧａＮ的质量与性能． 结果离子密度越高,薄膜的质量与性能就越好． 当生长ＧａＮ 时的离子密度为２－０ ×１０１１ ｃｍ － ３ 时,所得ＧａＮ 晶膜的氮镓量比接近于１ ,本底电子密度为３－７ ×１０１８ ｃｍ － ３ ,Ｘ 射线双晶衍射回摆曲线的半高宽为１６ ａｒｃｍｉｎ ． 结论　提高离子密度能明显提高ＧａＮ 的质量与性能     

Preparation of nanocrystalline BaTiO<Subscript>3</Subscript> ceramics

The high-dense nanocrystalline BaTiO₃ (BT) ceramics with grain size smaller than 100 nm have been successfully prepared by the two step sintering and the spark plasma sintering (SPS) process. The successive transitions in nanograin BT ceramics from rhombohedral to orthorhombic, tetragonal and cubic transitions, similar to those in coarse BT ceramics, were revealed by in-situ temperature dependent Raman spectrum. The multiphase coexistence and the diffused phase transition character were demonstrated in the 8 nm nanocrystalline BT ceramics. Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2002CB613301) and the National Natural Science Foundation of China (Grant No. 50872093)     

Multi-channel micro neural probe fabricated with SOI

Silicon-on-insulator(SOI) substrate is widely used in micro-electro-mechanical systems(MEMS).With the buried oxide layer of SOI acting as an etching stop,silicon based micro neural probe can be fabri-cated with improved uniformity and manufacturability.A seven-record-site neural probe was formed by inductive-coupled plasma(ICP) dry etching of an SOI substrate.The thickness of the probe is 15 μm.The shaft of the probe has dimensions of 3 mm×100 μm×15 μm with typical area of the record site of 78.5 μm2.The im...     

Dielectric Behavior of BaTiO3／ PVDF Nanocomposites In-situ Synthesized by the Sol-Gel Method

BaTiO3/ PVDF nanocomposites were prepared via in-situ growth of nanosized BaTiO3 particles in PVDF matrix by using the sol-gel method. The present elements of BaTiO3/ PVDF nanocomposites were analyzed by an electron probe X-ray microanalyser. Nanosized BaTiO3 grown in the composite films was characterized by an X-ray diffractometer and a transmission electron microscope, and the dielectric properties of the composite films were measured. The distribution of BaTiO3 nanoparticles in-situ grown in the PVDF matrix was examined using a scanning electron microscope.     

普适变量法在深空探测器轨道设计中的应用

给出了利用普适变量法来求解飞行时间，开普勒问题和高斯问题的计算方法，将这些方法用于深空探测器的轨道设计，针对不同要求提出了3种改进设计的方法，对每种方法的适用范围进行了详细的分析。在此基础上给出了深空探测器飞行轨道初步设计的完整方法。     

深空探测科学仪器研究进展

深空探测是对宇宙中地球以外的行星、卫星、小行星和彗星等星体或空间环境的探测活动.合理选择深空探测科学仪器,了解被测星体的物理及化学性质、地表地貌、动态特性以及有机物和水的存在,对人类了解地外水和生命信息、认识太阳系的起源和演化有着重要意义,是深空探测的重要任务.本文总结了深空探测的科学目标,介绍了近50年来典型深空探测...     

复杂工程地质体地应力场智能反演

地应力是地质构造和自重共同作用在地质体内形成的原始应力,是影响工程稳定性和灾变失稳的重要因素.由于受漫长的地质构造作用和地质演化,地应力场随时间和空间变化,由此使准确反演地应力场造成困难.以金川矿区为工程背景,借助地应力测量结果,开展工程地质体的地应力场反演研究.首先,建立矿区工程地质体三维数值模型,并采用正交数值分析和遗传规划算法,建立地应力与岩体参数和侧压系数的函数关系;然后,根据实测的地应力值与计算的地应力值之差平方和最小为优化目标,建立工程地质体的地应力场反演优化模型.采用遗传算法求解,获得矿区岩体参数和侧压系数;最后,将其代入数值模型进行正分析由此获得初始地应力场.通过4个测点地应力测量值与反演值对比分析可知,反演地应力的最大误差为16%,最小误差仅为0.62%.研究结果表明,地应力智能反演方法可用于复杂工程地质体的地应力场反演,且获得的地应力场满足地质工程分析所需要的精度.     

Cycle-by-Cycle Queue Length Estimation for Signalized Intersections Using Multi-Source Data

In order to estimate vehicular queue length at signalized intersections accurately and overcome the shortcomings and restrictions of existing studies especially those based on shockwave theory,a new methodology is presented for estimating vehicular queue length using data from both point detectors and probe vehicles. The methodology applies the shockwave theory to model queue evolution over time and space. Using probe vehicle locations and times as well as point detector measured traffic states,analytical formulations for calculating the maximum and minimum( residual) queue length are developed. The proposed methodology is verified using ground truth data collected from numerical experiments conducted in Shanghai,China. It is found that the methodology has a mean absolute percentage error of 17. 09%,which is reasonably effective in estimating the queue length at traffic signalized intersections. Limitations of the proposed models and algorithms are also discussed in the paper.     

华北重点矿区煤储层吸附特征及其影响因素

研究华北地区煤储层吸附特征及主要影响因素，对9个重点矿区42件煤样进行了平衡水法等温吸附分析．实验表明：研究区原煤兰氏体积在6．22～43．57m^3／t之间，分布特征受区域煤变质的三带分布规律控制，在中带的沁水盆地最高，焦作、安鹤、永夏和荥巩煤田其次，而在南、北两带的平顶山、大同和两淮地区最低；全区域兰氏压力在0．20～3．83MPa之间，以大同和沁水最高，平顶山次之，其他矿区较低．研究表明，煤级是影响该区煤储层吸附能力的主要因素，随煤级增大，煤储层吸附能力呈多项式关系增强．煤吸附能力随煤中镜质组和惰质组含量总和的增高而增强，其中惰质组的影响较大．煤储层吸附能力随煤中碳组分含量的增高和氢组分含量的降低而增高．煤中水分和灰分的存在会降低煤的吸附性能．     

地应力测量方法综述

通过回顾地应力测量的起源及发展历程,对地应力测量方法进行了归类分析,明确了各种方法的基本原理、优缺点及应用范围;同时,对地应力测量的最新发展趋势以及目前我国在地应力测量方面面临的问题与挑战进行了剖析．研究成果对于采用较好的地应力测量方法以提高地应力测量精度无疑具有重要的指导意义．     

Preparation and Dye Adsorption of Low-cost Polyaniline-tea Saponin Nanocomposites

Four polyaniline-tea saponin (PTS) nanocomposites were prepared by an in-situ polymerization with tea saponin (TS) as a biosurfactant,and they were used to remove organic dyes from aqueous solution.The PTS nanocomposites were characterized by using field emission scanning electron microscopy,the Fourier transform infrared spectroscopy,the Ultraviolet-visible spectroscopy,and the thermogravimetric analysis.The adsorption performances of the PTS nanocomposites for organic dyes were studied by a static adsorption method.The experimental results reveal that adsorption capacities of the PTS nanocomposites are higher than that of pure polyaniline.Especially,the PTS nanocomposites exhibit excellent adsorption performances for anionic dyes because of the electrostatic interaction between the positively charged nitrogen atoms on the PTS chains and the negatively charged sulfonate ions in the anionic dyes.According to the adsorption kinetics and thermodynamics results,the adsorption processes of PTS20 for CR and AB74 follow well with the pseudo second-order and Langmuir isotherm models.It is indicated that TS should be very useful in the preparation of PTS nanocomposite and in removal of toxic dyes from waste water.     

Thickness and component distributions of yttrium-titanium alloy films in electronbeam physical vapor deposition

Thickness and component distributions of large-area thin films are an issue of international concern in the field of material processing. The present work employs experiments and direct simulation Monte Carlo (DSMC) method to investigate three-dimensional low-density, non-equilibrium jets of yttrium and titanium vapor atoms in an electron-beams physical vapor deposition (EBPVD) system furnished with two or three electron-beams, and obtains their deposition thickness and component distributions onto 4-inch and 6-inch mono-crystal silicon wafers. The DSMC results are found in excellent agreement with our measurements, such as evaporation rates of yttrium and titanium measured in-situ by quartz crystal resonators, deposited film thickness distribution measured by Rutherford backscattering spectrometer (RBS) and surface profilometer and deposited film molar ratio distribution measured by RBS and inductively coupled plasma atomic emission spectrometer (ICP-AES). This can be taken as an indication that a combination of DSMC method with elaborate measurements may be satisfactory for predicting and designing accurately the transport process of EBPVD at the atomic level. Supported by the National Natural Science Foundation of China (Grant Nos. 90205024, 10502051 and 10621202)     

Microstructure and Properties of A IN Coating/Graphite Fabricated via In-situ Reaction

A novel method was used to fabricate AIN coating on graphite substrate.This approach included two steps:firstly,the emulsion composed of BN and anhydrous ethanol was sprayed on the surface of the graphite substrate;secondly,AIN coating was formed through the in-situ reaction of Al with the sprayed BN.The reaction was investigated by thermogravimetric-differential thermal analysis(TG-DTA),and the phase composition in the synthetic process was characterized by X-ray diffraction(XRD).Scanning electronic microscopy(SEM)was used to observe the morphology,and electron probe microanalysis(EPMA)was used to observe the distribution of the elements.The experimental results show that the AIN coating is dense and bonded with graphite tightly.     

Mierostrueture and Properties of A IN Coating/Graphite Fabrieated via In-situ Reaction

A novel method was used to fabricate AlN coating on graphite substrate. This approach included two steps： firstly, the emulsion composed of BN and anhydrous ethanol was sprayed on the surface of the graphite substrate; secondly, AlN coating was formed through the in-situ reaction of Al with the sprayed BN. The reaction was investigated by thermogravimetric-differential thermal analysis （TG-DTA）, and the phase composition in the synthetic process was characterized by X-ray diffraction （XRD）. Scanning electronic microscopy （SEM） was used to observe the morphology, and electron probe microanalysis （EPMA） was used to observe the distribution of the elements. The experimental results show that the AlN coating is dense and bonded with graphite tightly.     

Dielectric Behavior of BaTiO_3/ PVDF Nanocomposites In-situ Synthesized by the Sol-Gel Method

1　IntroductionFerroelectricceramic polymercompositesconsistingofferroelectricceramicpowderembeddedinapolymermatrixhaveattractedmuchattentionsincetheycombinetheexcellentferroelectricpropertiesoftheceramicsandtheflexiblemechanicalpropertiesofthepolymer[1] …     

氧化石墨/壳聚糖磁性复合吸附剂对活性艳红吸附性能研究

采用原位共沉淀法制备了氧化石墨/壳聚糖磁性复合吸附剂,研究了氧化石墨/壳聚糖磁性复合吸附剂对活性艳红的吸附行为,发现壳聚糖与氧化石墨的加入量为重量比在200:1时对活性艳红的吸附量最大.考察了氧化石墨/壳聚糖磁性复合吸附剂在不同pH值、不同时间下对活性艳红的吸附性能.实验结果表明,该吸附剂吸附活性艳红的最佳pH值为2,饱和吸附量为706mg/g,吸附速度快,对活性艳红的吸附在30min内达吸附平衡.吸附过程可用Langmuir吸附等温线描述,符合二级动力学方程.经10次吸附后,对活性艳红仍保留了初次吸附量的61%,具有一定的重复使用性.