用经典力学计算氢分子的键长键能及力常数

氢原子中1 s电子的电子云呈球形，电子的最大几率密度分布出现在玻尔半径a0的球壳内，认为几率密度分布及电子云属统计规律，意味着已经使用了宏观时标，这样就使氢分子体系中能量和时间的作用量远大于普郎克常数；根据电子云的交叠，用经典力学计算了基态氢分子的结构常数，获得键长、键能及力常数的表达式分别为采用原子单位（a.u.）时z、e及a0均为1，获得Re=1.414a.u.，De=0.177a.u.，k=0.354a.u.，这些数值与实验值的相对误差分别<1%，<2%和<4%；成键模型直观，物理意义明确，计算中不含任何人为性参数。     

核磁共振豫时间与磁共振成像

<正> 1.核磁共振驰豫时间(T_1,T_2)当氢原子核被置于固定的强磁场中时,会分成顺磁场和逆磁场两种方向排列,而形成两种能级状态。这时若用无线电波来照射这些氢原子核,各氢原子核会因周围环境的差异而吸收不同频率的无线电波的能量从低能级向高能级跃迁,这种现象称核磁共振(NMR)。使氢原子核发生核磁共振的条件是:ω=26753H_0式中 H_0表示氢原子核周围磁场的强度,ω表示使该氢原子核产生共振跃迁的无线电波的频率,比例常数26753,是氢原子核的旋磁     

微纳米级键合强度分析(英文)

本文主要研究了微米/纳米尺度的键合技术和键合强度,给出并发展了基于MEMS技术的微米/纳米键合分析模型.为提取微米/纳米键合面积的最大剪应力和压应力,设计、制备和测试了一系列单晶硅悬臂梁结构.并使用理论公式和ANSYS有限元模拟对实验结果进行了分析.键合强度可以分为扭转和剪压表征两部分.根据测试值可得,最大抗扭强度为1.9×109μN.μm,最大压应力为68.3 MPa.     

天然矿物电气石产生空气负离子性能研究

以桂林电气石和阿尔泰电气石为原料，研究了它们产生的空气负离子性能。用红外光谱仪、X射线衍射仪、扫描电镜对这两种电气石进行了分析表征。结果表明：桂林电气石为铁电气石，平均能够产生空气负离子692个／cm^3，相对增加空气负离子394个／cm^3；阿尔泰电气石为铁镁电气石，平均能够产生空气负离子935个／cm^3，相对增加623个／cm^3；两种电气石吸收或辐射的主要红外波段基本一致，都存在比较多的红外活性键，但是阿尔泰电气石在7．39gm处多出现了一个B-O键辐射或吸收峰。     

座舱显示器周边各键尺寸、方位和间隔的工效学实验研究

飞机座舱显现器周边各键是重要控制器，它的尺寸、方位、排列方向、键间隔是影响工效的重要因素。该研究用两个实验探讨了周边各键的尺寸、方位、间隔对反应时的影响。结果表明：键尺寸、方位、排列方向对反应时有影响，键的间隔对反应时没有影响     

含Nd镁铝合金电子结构计算与强化机制分析

基于EET理论,计算了Nd元素加入Mg-Al合金后形成的Mg-Al-Nd固溶体,第二相Al2Nd,Al3Nd价电子结构,研究了价电子结构与合金固溶强化、第二相强化、高温稳定性和晶粒细化的关系.Mg-Al-Nd最强键共价电子对数nA值和共价电子密度ρCV值均大于α-Mg的nA值和ρCV值,表明Nd的固溶有利于基体强度的提高;第二相Al2Nd最强键(nA=0.44396)与Al3Nd最强键(nA=0.38949)的键合强度均远大于基体α-Mg(nA=0.11199)的键合强度,因此,Al2Nd和Al3Nd极大地阻碍了位错的运动,提高了合金的强度;Al2Nd和Al3Nd的单位体积成键能力FV值分别为145.91和242.35,与γ-Mg17Al12(Fγ-Mg17Al12V＝44.22)相比较,它们的高温稳定性更好,其存在有利于改善Mg-Al合金的高温性能;Nd提高了液态合金中邻近原子间键合强度,增加了基体的形核率,减缓了晶粒长大速度,进而细化了晶粒,提高了合金的力学性能.     

承压型组合剪力键剪切性能试验与承载力计算

针对抗剪需求较大的钢-混凝土组合结构，改进了一种带横向焊钉的承压型组合剪力键。设计并开展了10个承压型组合剪力键和1个非承压型组合剪力键单调推出试验，明确了混凝土端部承压、混凝土强度、肋板厚度、肋板孔径和焊钉直径对承压型组合剪力键失效模式和破坏过程的影响。建立了承压型组合剪力键有限元模型，在结合试验验证仿真模型可靠性的基础上，进一步揭示了承压型组合剪力键受力机理。以试验变量为基础，建立并分析了108个承压型组合剪力键有限元模型，推导了承压型组合剪力键极限承载力与各参数变量之间的线性关系，对极限承载力分析结果进行多元线性回归提出了承压型组合剪力键极限承载力计算模型。结果表明：承压型组合剪力键混凝土板失效模式为大面积竖向裂缝和端部裂缝，内表面形成由焊钉高度附近向下延伸的斜主裂缝，非承压型组合剪力键混凝土板无明显端部裂缝，承压型组合剪力键极限承载力约为非承压型组合剪力键的1.4倍；与肋板孔径和焊钉直径相比，承压型组合剪力键极限承载力对混凝土强度和肋板厚度更为敏感。该研究提出的承压型组合剪力键极限承载力计算公式物理意义明确，计算值与仿真和试验结果吻合较好，可为组合剪力键设计和工程应用提供参考。     

等离子体裂解天然气制纳米炭黑和乙炔

利用200KW的中试装置，在常压下研究了天气然在氮热等离子体中的裂解行为，考察了输入功率、甲烷流量以及CH4／N2比对反应的影响。结果表明：天然气在氮热等离子体中发生了强烈的分解反应，生成大量炭黑和C2烃；CH4／N2为0．4，输人功率120千瓦时，炭黑的收率为42．0％，甲烷的转化率为97．1％；所制得的炭黑平均粒径38nm，分布范围狭窄；炭黑的DBF，吸收值1．40ml／g，是一种高结构性炭黑。红外光谱分析发现炭黑中存在芳香C-C键及大量氮基官能团如-NH、-CN等以及-CH，-OH，-COOH等。     

引线键合系统键合工具振动特性研究

研究微电子封装超声引线键合系统键合工具的动态特性和摩擦行为,运用有限单元法建立了键合工具的动态接触模型,初步掌握微电子超声键合系统键合机理。通过对键合工具施加不同的加载频率和正压力的计算结果进行对比,定性地给出了键合过程中加载频率和正压力的变化对键合工具动态响应和摩擦应力的影响.研究结果表明:键合工具的加载频率偏离固有频率,键合工具针尖部分的幅值响应将迅速减小,同时摩擦应力的均值也相对减小;正压力增大,响应幅值将会相应减小;正压力增大到一定值时,幅值响应将会波动比较大,如果要得到适合的键合点尺寸的要求,同时保证键合质量,就必须选择合适的加载频率和正压力。     

电厂辅助锅炉的自动控制

介绍了平衡通风燃油辅助锅炉的炉型特点；设计了合理的控制流程，采用一键启动控制和MFT保护措施，以确保辅助锅炉安全稳定运行。     

The contributions of microrotation of lubricant molecules in a thin film journal bearing

Summary Characteristics of a journal bearing were computed for thin film lubrication accounting for microrotation of the lubricant molecules using both the half-Sommerfeld and Reynolds boundary conditions. Although the Reynolds boundary conditions produced higher pressure and loads, the effects of microrotation studied by both schemes showed similar trends. Primary characteristics that effect the contributions of microrotation to the load carrying capacity of the journal bearing were identified. These characteristics were varied and their effects on the load capacity of the journal bearing are shown.Nomenclature a circumference of the shell, 2R - a ₁,a ₂,a ₃ constants - c radial difference between the shaft and shell, [R-r] - c ₁,c ₂,c ₃,c ₄ solving partial differential equations constants - e eccentricity - F ^* body force per unit mass - G substitute function for integration - h film thickness - j microinertia constant of the fluid - K ₁,K ₂ defined after Eq. (2.27) - l material length, - L ^* body couple - m - N coupling number, - p pressure - p ₀ ambient pressure - Q fluid flux flow through the cavity cross section - r shaft radius - R shell radius - R _h modified Reynold number, - R _l Reynolds number, - t time - u, v velocity components inx-andy-direction, respectively - u ₀ velocity of the shaft surface - V velocity vector - W load carrying capacity - W load component resulting from pressure parallel to the line of centers - W load component resulting from pressure perpendicular to the line of centers - x, y, z Cartesian coordinates - , , , micropolar viscosity coefficients - ₁, ₂ parameters of boundary conditions for the microrotation vector at the shell and shaft, respectively - the deviate angle of the load direction from the line of centers - e/c - , Newtonian viscosity coefficients - microrotation velocity vector - microrotation velocity component in thez-direction - angular velocity of the shaft - ^* thermodynamic pressure - mass density of the lubricant fluid - polar angle around the journal bearing - ^* angle which satisfies Reynold's B.C.     

Setting expansion of gypsum-bonded investment in dental casting

The values of setting expansion of investment under uniaxial stress have been determined at conditions designed to obtain the difference of setting expansion between that parallel to the loading direction and that perpendicular to the loading axis. The setting expansion curves were represented by $$a(t) = a_0 (1 - P/E')[1 - exp( - kt)]$$ along the loading direction and $$a(t) = a_0 (1 + \nu 'P/E')[1 - exp( - kt)]$$ perpendicular to the loading direction, wherea(t) is a setting expansion,a ₀ = 0.009,ν′ = 0.2,E′ = 5 kg cm^?2,k = 0.032 min^?1,P applied stress, andt the time (min). On the basis of these results, a method to estimate the value of setting expansion under restrictive force was developed. According to this method, the setting expansion of the investment could be calculated by substituting?ε/?t forε, ka ₀ exp (?kt)/E′ for 1/E, ν′ forν, andka ₀ exp (?kt) forαT in the theory of elasticity.     

Standard electrochemical behavior of high-quality, boron-doped polycrystalline diamond thin-film electrodes

Standard electrochemical data for high-quality, boron-doped diamond thin-film electrodes are presented. Films from two different sources were compared (NRL and USU) and both were highly conductive, hydrogen-terminated, and polycrystalline. The films are acid washed and hydrogen plasma treated prior to use to remove nondiamond carbon impurity phases and to hydrogen terminate the surface. The boron-doping level of the NRL film was estimated to be in the mid 1019 B/cm3 range, and the boron-doping level of the USU films was approximately 5 x 10(20) B/cm(-3) based on boron nuclear reaction analysis. The electrochemical response was evaluated using Fe-(CN)6(3-/4-), Ru(NH3)6(3+/2+), IrCl6(2-/3-), methyl viologen, dopamine, ascorbic acid, Fe(3+/2+), and chlorpromazine. Comparisons are made between the apparent heterogeneous electron-transfer rate constants, k0(app), observed at these high-quality diamond films and the rate constants reported in the literature for freshly activated glassy carbon. Ru(NH3)6(3+/2+), IrCl6(2-/3-), methyl viologen, and chlorpromazine all involve electron transfer that is insensitive to the diamond surface microstructure and chemistry with k0(app) in the 10(-2)-10(-1) cm/s range. The rate constants are mainly influenced by the electronic properites of the films. Fe(CN)6(3-/4-) undergoes electron transfer that is extremely sensitive to the surface chemistry with k0(app) in the range of 10(-2)-10(-1) cm/s at the hydrogen-terminated surface. An oxygen surface termination severely inhibits the rate of electron transfer. Fe(3+/2+) undergoes slow electron transfer at the hydrogen-terminated surface with k0(app) near 10(-5) cm/s. The rate of electron transfer at sp2 carbon electrodes is known to be mediated by surface carbonyl functionalities; however, this inner-sphere, catalytic pathway is absent on diamond due to the hydrogen termination. Dopamine, like other catechol and catecholamines, undergoes sluggish electron transfer with k0(app) between 10(-4) and 10(-5) cm/s. Converting the surface to an oxygen termination has little effect on k0(app). The slow kinetics may be related to weak adsorption of these analytes on the diamond surface. Ascorbic acid oxidation is very sensitive to the surface termination with the most negative Ep(ox) observed at the hydrogen-terminated surface. An oxygen surface termination shifts Ep(ox) positive by some 250 mV or more. An interfacial energy diagram is proposed to explain the electron transfer whereby the midgap density of states results primarily from the boron doping level and the lattice hydrogen. The films were additionally characterized by scanning electron microscopy and micro-Raman imaging spectroscopy. The cyclic voltammetric and kinetic data presented can serve as a benchmark for research groups evaluating the electrochemical properties of semimetallic (i.e., conductive), hydrogen-terminated, polycrystalline diamond.     

分光光度法测定络合物稳定常数的数据处理问题

本文论述关于分光光度法测定络合物稳定常数中的两个问题,一个是关于消光值的校正方法问题,一个是关于络合稳定常数K的计算问题,即采用迭代法解方程K=求得x的值。     

Representation of the magnetization characteristic by a sum of exponentials

It is possible to set up equations of the formB(H) = a_{0} + a_{1} e^{-alpha_{1}H} + a_{2} e^{-alpha_{2}H} + a_{3} e^{-alpha_{3}H} + a_{4} e^{-alpha_{4}H}on an analog computer to fit accurately aB-Hcurve of any magnetic material over the whole range from zero to the knee of the curve to the saturation part of the curve.     

Analysis of Hydrogen Diffusion in Metals with Trapping under Local Equilibrium Assumption

The assumption of the local equilibrium ofhydrogen distribution in metals[1]was used in themodel formerly developed[2]to describe the diffu-sion of hydrogen in metals.From the assumption adirect relationship between the hydrogen diffusivityand the hydrogen concentration in metals is estab-lished asD=D_o/{1+N_x(k/p)/[1+C(k/p)]}The comparison between the two results drawnfrom the assumption of equilibrium and the dynam-ics of hydrogen trapping[3]was also presented.Thecomputation results well explained the scatteringphenomenon existed in hydrogen diffusion data andsuggested that the experimental conditions shouldbe identical for the study of hydrogen permeation inmetals.     

Kinetics of decolorization of an azo dye in UV alone and UV/H(2)O(2) processes

The decolorization of C.I. Acid Red 27 (AR27), a monoazo anionic dye, was studied in the ultraviolet radiation (UV) alone and UV plus hydrogen peroxide (UV/H(2)O(2)) processes. The experimental results indicated that the kinetics of both oxidation processes fit well by pseudo-first order kinetics. The reaction rate was sensitive to the operational parameters and increased with increasing H(2)O(2) concentration and light intensity. The reaction orders of H(2)O(2) concentration and light intensity in both processes were obtained with linear regression method. A regression model was developed for pseudo-first order rate constant (k(ap,UV/H(2)O(2))) as a function of the Cconcentration and UV light intensity. (k(ap,UV/H(2)O(2)))=(2 x 10(-4)I(0.75)(0) + k(3)I(1.38)(0)[H(2)O(2)](n)(0))phi(AR27). As a result of two opposing effects of H(2)O(2) concentration at low and high concentrations, n has a value of 0.49 and -0.39 and k(3) has a value of 3 x 10(-4) and 0.1 for the regions of 0 mg l(-1) < [H(2)O(2)](0) < 650 mg l(-1) and 650 mg l(-1) < [H(2)O(2)](0) < 1500 mg l(-1)1, respectively. PhiAR27 is the initial dye concentration correlation index for developing of model for different initial concentrations of AR27. This rate expression can be used for predicting k(ap,UV/H(2)O(2) at different conditions in UV alone and UV/H2O2 processes. The results show that UV alone cannot be an efficient method for decolorization of AR27 in comparison with UV/H(2)O(2) process, therefore the first term of the model can be neglected.     

Transient Creep Associated with Grain Boundary Sliding in Fine-Grained Single-Phase Al2O3

Transient creep data for high-purity polycrystalline alumina are examined at the testing temperature of 1150–1250 °C. The data are analysed in terms of the effect of stress and temperature on the extent of transient time and strain.In order to explain the observed transient creep, a time function of creep strain is proposed from a two-dimensional model based on grain boundary sliding. The grain boundary sliding is assumed to take place by the glide of grain boundary dislocations accommodated by dislocation climb in the neighboring grain boundaries. The time function for a creep strain obtained from the model is given in a form

Edge pinning in superconducting thin films in perpendicular magnetic fields

Two-dimensional systems of bosons and fermions are studied at zero temperature by means of variational calculations. When viewed as a function of the quantum parameter = ²/m in the variational context, bosons are found to undergo a second-order liquid-to-gas transition, whereas, contrary to expectations, fermions are found to undergo a first-order transition with a region in which liquid and gaseous phases can coexist. Although these results are qualitatively the same as those in three dimensions, it is emphasized that, for two-dimensional fermions, the underlying physics is quite different. These results are examined critically in view of the special properties of two-dimensional systems. It is found that critical values of are rigorously lower bounds, and it is further argued that the essential features of these results remain valid. Finally, the implications of these results for experiments on submonolayer physisorbed helium and spin-aligned hydrogen systems are discussed.This research was supported, in part, by the National Science Foundation under grants DMR76-14447 and DMR73-02609.This research was performed as part of the NSF Independent Research Program. However, any of the opinions expressed herein are those of the author (LHN) and do not necessarily reflect the views of the NSF.