信号调制法测量中性粒子ESD脱附截面

SD截面是电子诱导脱附研究中的用以描述脱附产物的一个重要物理量 ,中性粒子ESD脱附截面的测量一直是ESD截面测量中比较难以解决的问题。本文介绍了利用信号调制法测量了中性粒子ESD脱附截面的原理 ,同时利用该方法测量了 1× 10 -3 Pa下 ,N2 从多晶W表面脱附时N2 的中性脱附产物的ESD截面 ,并对实验方法及测量结果进行了分析讨论。该方法有效地解决了中性粒子ESD截面的测量问题     

负载型Pt/CeO2催化剂上N2O的生成机理

以水热法结合固相研磨法制备了Pt/CeO2催化剂粉体,探究了笑气(N2O)的生成机理及贵金属负载量对笑气产率的影响.研究结果表明,随着Pt负载量的增加,N2O选择性先增加后下降,其中负载0.5 wt％Pt的催化剂的N2O选择性最高,在275℃时达到85.1％.通过包括程序升温还原(TPR)及程序升温脱附(TPD)等方法...     

KOH活化制备石油焦基微孔活性炭及表征

以新疆克拉玛依石油焦为原料,KOH为活化剂,在N2保护下,采用化学活化法制备高比表面积活性炭。系统考察了碱焦比、活化温度、活化时间以及N2流速对所制备活性炭的碘吸附值及产率的影响。结果表明:当碱焦比为4∶1、活化温度为800℃、活化时间为0.5h及N2流速为50mL/min时,制备出的活性炭BET比表面积高达2806.69m2/g,碘吸附值为2941mg/g,活化产率为62.1%。采用N2吸附-脱附及X射线衍射等实验手段对活性炭进行了表征。     

制备工艺对褐煤基颗粒活性炭PSA分离CH4/N2性能的影响

以褐煤为原料,可溶淀粉作粘结剂,采用不同工艺制备PSA分离CH4/N2用颗粒活性炭,探讨了制备工艺及粘结剂添加比例、升温速率和活化水用量对样品分离性能的影响.结果表明,对原料碳化/水洗脱灰、添加碱式碳酸镁可以提高样品的分离性能;原料碱洗脱灰、预氧化及添加KOH不利于PSA分离CH4/N2用颗粒活性炭的制备;当碳化温度和...     

有机改性蒙脱土的制备及其工艺方法研究

以钠基蒙脱土为原料,用十六烷三甲基溴化铵作有机插层剂对蒙脱土进行有机化处理,制备出层间距不同的有机蒙脱土。并在此基础上,采用低聚物,用机械共混的方法来进一步扩大有机蒙脱土的层间距。用xRD、TEM对产品进行表征。探讨了有机改性的工艺条件及低聚物加入量对有机蒙脱土层间距的影响情况。结果表明,在浓度6％、处理时N90min、温度80℃条件下,蒙脱土有机化效果较好,低聚物的加入量为6％时有机蒙脱土的层间距最大。     

GaAs基片高温加热清洗过程中残气脱附的研究

为了优化GaAs基片的加热清洗工艺,获得原子级清洁表面,用四极质谱仪研究了GaAs基片高温加热清洗过程中常见气体及Ga、As元素的脱附规律.研究结果表明:常见气体(H2、H2O、N2、CO、CO2、Ar、CxHyOz)在100℃左右开始大量脱附;Ga、As元素主要以单质和氧化物的形态脱附,其脱附的温度存在两个峰值,分别是300℃和600℃;研究还发现真空环境中某些常见气体的含量会影响到Ga、As元素的脱附形式,当H2含量较高时,一部分As会以AsH3的形态脱附,当H2含量较低时,As基本以单质的形态脱附.经过多次实验及对实验结果的分析,最终确定了高温加热清洗的升温曲线及加热清洗的最高温度,获得了较为理想的原子级清洁表面.     

蒙脱土插层改性酚醛树脂复合材料及其摩擦磨损性能

利用单体原位插层的方法制备酚醛树脂/蒙脱土复合材料,研究了蒙脱土的有机化改性和不同有机化蒙脱土含量对酚醛树脂耐热性的影响,以及改性后的酚醛树脂对摩擦材料性能的影响,结果表明:经改性的酚醛树脂的耐热性能要明显优于未改性的酚醛树脂,初始分解温度达487.1℃,比未改性的提高了60.9℃,600℃时的质量剩余率达54.84%,提高了38%。100~350℃摩擦系数为0.33~0.40,250℃时未改性树脂基摩擦材料磨损率为0.56×10-7/N·m,改性后树脂基摩擦材料磨损率为0.44×10-7/N·m,下降了27.2%。     

水溶性壳聚糖的制备及表征

以高脱乙酰化的壳聚糖为主要原料 ,在乙酸水溶液 -乙醇 -吡啶介质中 ,实现了壳聚糖的 N位均相乙酰化反应 ,制备了脱乙酰度为 5 0 %左右 ,在 p H=1～ 14范围内具有良好水溶性的壳聚糖。重点考察了乙酸酐用量对脱乙酰度的影响 ,结果表明 ,当乙酸酐用量与壳聚糖的摩尔比在 2 .0左右时 ,产物的脱乙酰度接近 5 0 % .通过对所用的高脱乙酰度壳聚糖特性粘度 [η]的测定 ,间接得到了产物的分子量为 1.66×10 5左右。对产物进行了 FT- IR及 1H- NMR表征 ,谱图中与乙酰胺基有关的信号均发生了变化 ,表明了乙酰化反应的发生。     

后天抑制剂取向硅钢析出物的研究

采用"后天抑制剂法"制备取向硅钢,通过TEM研究热轧、常化、脱C和渗N阶段析出物的类型和分布。结果表明,热轧、常化和脱C板中的析出物主要是AlN颗粒,AlN颗粒在热轧、常化和脱C板中分布密度低;渗N后钢中形成非晶态Si3N4颗粒,非晶态Si3N4颗粒有多边形大块状和规则小四方形2种形貌,多边形大块状Si3N4颗粒分布在晶界,规则小四方形Si3N4颗粒主要分布在晶内。     

D-萘普生温敏分子印迹凝胶的制备及吸附性能研究

采用热聚合方法,以D-萘普生(D-Npx)为模板分子,N-异丙基丙烯酰胺(NIPAAm)为功能单体,N,N’-亚甲基双丙烯酰胺(MBAA)和二甲基丙烯酸乙二醇酯(EGDMA)分别为交联剂,制备了一种温敏D-Npx分子印迹凝胶(MIH),研究了凝胶的温敏性以及交联剂的种类和浓度对凝胶结构和分离性能等的影响。研究结果表明,随着MBAA含量的增加,MIH的平衡溶胀率降低,且MIH对D-Npx的吸附和脱附量先增加后逐渐减少;随EGDMA含量的增加,MIH对D-Npx的吸附和脱附量逐渐增大。MIH具有明显的温敏性,MBAA含 量 对 凝 胶 的 最 低 临 界 溶 解 温 度(LCST)几乎没有影响,凝胶表现出较好的溶胀-退胀性,脱附率可达90%以上。     

镍基高温合金脱氮工艺的研究

研究了真空感应熔炼镍基高温合金过程中的脱氮工艺并初步分析了镍基高温合金中钛对氮的相互作用,近似地计算出其相互作用系数.在现有的条件下,本研究的目的是获得实验数据以此来分析氮的含量并计算出钛对氮的相互作用系数,从而确定最佳的脱氮工艺.     

A numerical method for determining the kinetic constants of gas–liquid metal interactions in N–Ni–20Cr and N–ASTM F-75 alloy systems

In gas–liquid interaction systems, under non-equilibrium degassing conditions, the rate of a particular process often follows a mixed control regime where serial-acting mechanisms affect the global rate of the process and, therefore, the determination of real kinetic constants is difficult. In this paper a numerical method for determining these kinetic constants is presented and applied to the cases of denitrogenation of liquid Ni–20Cr alloys at 1873 K and nitrogen absorption in liquid ASTM F-75 alloys at 1773 and 1823 K. The results showed that interaction kinetics of nitrogen with both alloys was limited by both first and second order mechanisms. This results permit manufacturing engineers to act on the process parameters in order to obtain the nitrogen content that allows the best performance of mechanical parts.     

Effects of Temperature and [S] on the Kinetics of Nitrogen Removal from Liquid Steel

The kinetics of denitrogenation from liquid steel was studied by using an oxygen-nitrogen analysis system(LECO TC-436) under 1600℃ similar to 2813℃ conditions. The results show that when [S]=0.005%, nitrogen removal was controlled by nitrogen transfer in liquid diffusion layer, when [S]=0.012% and 0.140%, it was controlled by both nitrogen transfer in liquid diffusion layer and the chemical reaction at the liquid-gas interface below 2250℃, and by nitrogen transfer in liquid diffusion layer under 2250℃ similar to 2813 degreesC conditions. The activation energy E-a was 57 kJ/mol for 0.0050%[S], 95 kJ/mol for 0.012%[S], 165 kJ/mol for 0.140%[S]. The resistance of sulphur on nitrogen removal decreased with the temperature rose, and disappeared at 2630℃. Based on the results obtained, it has been answered why the nitrogen in liquid steel can be decreased rapidly by carbon-oxygen reaction under very high oxygen and sulphur content conditions during the BOF, EAF, VOD and AOD steelmaking processes.     

碳纤维制造过程中径向差异表征及演变机理

为优化PAN基碳纤维结构,采用AES表征PAN纤维在低温碳化与高温碳化后C,N,O沿纤维径向的分布,并用以阐明预氧化碳化过程径向差异的形成机理.结果表明:预氧丝径向结构不均匀,由外向内氧化程度降低;预氧时物理阻隔与化学阻隔导致径向形成氧浓度梯度,热物理传递与化学反应放热导致径向形成温度梯度.低温碳化时,热物理传递与化学反应放热形成温度梯度加剧了预氧时的径向差异;纤维分3部分,最外层氧含量低,由氧化程度高的预氧皮层外部强烈脱氮脱氧形成,最内层由氧化程度低的预氧芯层转化而成;中间是过渡层,一部分由氧化程度较高的预氧皮层内部少量脱氧脱氮而成,氧含量高,而后过渡到预氧程度低的低含氧量芯部.高碳丝径向组分差异变小,纤维分两部分,外层厚度仅为纤维直径的10%,是碳含量逐渐降低的过渡性皮层,其余部分为组成均一的芯层.     

Model fuel desulfurization and denitrogenation using copper and cerium modified mesoporous material (MSU-S) through adsorption process

The application of MSU-S, CeO₂-MSU-S, and Cu₂O-MSU-S in desulfurization and denitrogenation of model fuel containing benzothiophene (BT), dibenzothiophene (DBT), quinoline and carbazole were studied in batch and continuous process. The copper-modified MSU-S showed the highest capacity to adsorb sulfur and nitrogen compounds compared to other adsorbents. The adsorption selectivity of all adsorbents for nitrogen was slightly higher than for sulfur, indicating the selective adsorption of nitrogen over sulfur. The Langmuir model represented better equilibrium data fitting than Freundlich model for carbazole, DBT, and BT adsorption on MSU-S, CeO₂-MSU-S, and Cu₂O-MSU-S. It was found that quinoline adsorption data on MSU-S, CeO₂-MSU-S, and Cu₂O-MSU-S can be presented by Freundlich model very well. The kinetics of adsorption followed the pseudo-second-order model for all species over each adsorbent. According to the breakthrough curve order, the adsorptive selectivity for the adsorbates increased in the order of DBT < BT < carbazole < quinoline for MSU-S and CeO₂-MSU-S, and BT < DBT < carbazole < quinoline for Cu₂O-MSU-S.     

Deformation limits for corrugated cross-ply laminates

This work determines the maximal possible deformations of a corrugated sheet where the corrugation pattern consists of two circular segments. The influence of the lay-up of cross-ply laminates and the influence of the geometry is investigated. The calculations are based on considerations of layerwise strains that are calculated with the help of an analytical singly-curved shell model. For the evaluation of the influence of geometric nonlinearities according finite element simulations are performed and compared to the linear strain limit calculations. The influence of scalable geometry parameters is also investigated.     

Social Influence Analysis: Models,Methods, and Evaluation

Social influence analysis (SIA) is a vast research field that has attracted research interest in many areas. In this paper, we present a survey of representative and state-of-the-art work in models, methods, and evaluation aspects related to SIA. We divide SIA models into two types: microscopic and macroscopic models. Microscopic models consider human interactions and the structure of the influence process, whereas macroscopic models consider the same transmission probability and identical influential power for all users. We analyze social influence methods including influence maximization, influence minimization, flow of influence, and individual influence. In social influence evaluation, influence evaluation metrics are introduced and social influence evaluation models are then analyzed. The objectives of this paper are to provide a comprehensive analysis, aid in understanding social behaviors, provide a theoretical basis for influencing public opinion, and unveil future research directions and potential applications.     

弯曲刚度对斜拉索非线性固有频率的影响

考虑斜拉索的弯曲刚度、垂度及几何非线性,利用Hamilton变分原理推导了斜拉索的三维非线性动力学方程。研究了斜拉索弯曲刚度对面内、面外的一阶及高阶固有频率的影响,并分析了斜拉索长度和初张力等参数对固有频率的影响。结果表明:弯曲刚度对面外固有频率的影响大于面内;随着斜拉索的长度和初张力的增加,弯曲刚度对面外固有频率的影响递减,对面内固有频率的影响呈钟罩型变化;弯曲刚度对固有频率的影响随着振型阶数的增加而变大。     

Determination of influence weights for scientific journals

A new citation matrix is proposed for the computation of journal influence weights applying Geller's methodology. Instead of self-citations, references to fringe journals are introduced and the proportions of all references (without self-citations) are used as matrix elements. On the basis of the determined weights, relative weights for fringe journals are calculated, i.e. the initial set (core) of journals is extended and simultaneously a rank order is obtained (by total influence and influence per article). The procedure is examplified on elementary particle physics (EPP) journals. Using first a reference/citation criterion, eight core journals were determined by iteration and then influence weights were calculated. A ranking by total influence and influence per article is presented for core and fringe journals in EPP.     

半解析法确定大型桥跨结构的影响场

本文引出了影响场的概念,给出了用半解析分析法确定大型桥跨结构影响场的原理与方法：并以某大型悬索桥为例,计算了桥跨结构某处的应力影响场,得出了一些很有意义的计算与分析结果。