Analysis of total nitrogen and total phosphorus in soil using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy(LIBS) is used to determine the total nitrogen(TN) and total phosphorus(TP) in soil.Quantitative determinations are conducted using the line intensity of the analyte element and element concentration.Calibration models are obtained using ten samples for TN and seven samples for TP.The rest samples are used to validate the results.Strong linear correlations are obtained from the determined TN and TP concentrations.LIBS is a powerful tool for analyzing soil samples to determine nutrient elements by selecting calibration and validation samples with similar matrix composition.     

移动通信系统VoIP高效传输方法

研究在移动通信终端和P-GW/GGSN之间采用短标签替代VoIP标准协议头以提高传输效率的传输方案与实现方法。     

基于数据挖掘的刮刀压力对印刷质量影响分析

针对电子产品制造的锡膏印刷过程参数众多、交互作用复杂的问题，文中利用神经网络算法建立一种短时印刷质量预测模型。对基于刮刀压力设置值和基于刮刀压力实际值的模型精度进行比较，结果表明，基于实际值的模型误差为2.12%，基于设置值的模型误差为5.42%，基于实际值模型的精度优于基于设置值的模型。进一步分析具体数据发现，基于刮刀压力设置值模型误差较大的原因是：不同设置值对应的实际值波动较大，且设置粒度分辨力无法完全区分不同设置值对应的实际值。由于设置值和实际值存在较大差异，印刷时钢网承受的压力与预设的压力值范围不同，导致实际的下锡量与参数调整时预想不同，所以刮刀压力设置值的印刷质量预测模型精度较差。     

OTT是一种分众化的营销模式

OTT已然成为业界追逐的一个热词,然而,OTT到底应该怎么做,却已经是一片百家争鸣的景象。条条大路通罗马,作为一个现象或过程,不管是IPTV+OTT还是DVB+OTT,都是向OTT变革的路径之一,但OTT本身不是一个虚拟的概念或者标签,而是整个信息革命带来的商业模式变革的结果,是被互联网扁平化,提升效率之后对传统业务模式的流程再造。     

强拟诣零clean环（英文）

环R中元素a称为强拟诣零clean元,若存在幂等元e∈R和拟幂零元q∈R使得eq=qe且a=e+q;称环R为强拟诣零clean环,如果R中每一个元素均是强拟诣零clean元.强拟诣零clean环介于强诣零clean环和强clean环之间,并且每一个强拟诣零clean元是强clean元.本文介绍了强拟诣零clean环的基本性质和结构,并研究了局部环R上广义矩阵环K_s(R)的强拟诣零clean性.     

Monolithic integration of an AlGaN/GaN metalinsulator field-effect transistor with an ultra-low voltage-drop diode for self-protection

In this paper,we present a monolithic integration of a self-protected AlGaN/GaN metal-insulator field-effect transistor(MISFET).An integrated field-controlled diode on the drain side of the AlGaN/GaN MISFET features a selfprotected function for a reverse bias.This diode takes advantage of the recessed-barrier enhancement-mode technique to realize an ultra-low voltage drop and a low turn-ON voltage.In the smart monolithic integration,this integrated diode can block a reverse bias(> 70 V/μm) and suppress the leakage current(< 5 × 10-11 A/mm).Compared with conventional monolithic integration,the numerical results show that the MISFET integrated with a field-controlled diode leads to a good performance for smart power integration.And the power loss is lower than 50% in conduction without forward current degeneration.     

超弹性石墨烯气凝胶的制备及其性能

以多胺小分子二乙烯三胺(DETA)为还原剂和结构增强剂,采用水热还原法,制备了具有三维交联网络结构的高弹性石墨烯气凝胶(GA)。通过X射线衍射仪(XRD)、四探针测试仪、扫描电子显微镜(SEM)、万能拉力机和吸附实验等手段对GA的微观结构和性能进行了表征和测试。研究了氧化石墨烯(GO)和DETA的质量浓度对GA性能的影响。结果表明:GA的密度和导电率随着GO和DETA的质量浓度变化而变化,压缩强度随着GO和DETA质量浓度的升高而增大。当GO的质量浓度为8mg/mL,GO与DETA的质量浓度之比为1 000∶7.5时,其最大压缩强度高达6.8 MPa。GA被压缩后,其形貌可基本完全回复,表现出较好的抗疲劳性能。GA对7种常见有机溶剂的吸附量为自身质量的41~83倍,其中对二氯甲烷的吸附量最大,达到了自身质量的83倍。     

Synthesis and Crystal Structure of （E）-2-phenyl-6,7dihydrobenzofuran-4（5H）-one O-cyanomethyl Oxime

A pair of E/Z-isomers of 2-phenyl-6,7-dihydrobenzofuran-4（5H）-one O-cyanomethyl oxime,C16H14N2O2,as potential drugs for treating peptic ulcer and other acid-related diseases have been synthesized and characterized by IR,MS and NMR spectra.Meanwhile,the crystal of IIIa was obtained and determined by X-ray single-crystal diffraction.Crystal data： monoclinic system,space group P21 /c,a = 8.423（8）,b = 19.596（16）,c = 8.770（8）,β = 107.750（12）°,V = 1379（2）3,Z = 4,F（000） = 560,Dc = 1.283 g/cm3,μ = 0.086 mm 1,R = 0.0681 and wR = 0.2029 for 14472 independent reflections（Rint = 0.0782） and 2428 observed ones（I 2σ（I））.     

香芹酮的选择性环氧化

选择性是有机化学的核心概念之一,也是有机化学研究的关键问题之一。本实验以左旋香芹酮为原料,利用其两个碳碳双键性质的不同,使用两种不同的氧化方式进行选择性环氧化;对香芹酮两个碳碳双键的环氧化体现出化学选择性,而对应的产物是否为异构体混合物则体现出立体选择性。整个实验使用的原料和试剂便宜易得,反应操作简单且后处理容易,产物收率较高,适合本科有机化学实验教学,可帮助学生加深对化学选择性和立体选择性的认识和理解。