LIOUVILLE PROPERTY FOR A CLASS OF QUASI-HARMONIC SPHERE

In this paper we obtain a Liouville type result for a class of quasi-harmonic spheres with rotational symmetry.

Study on Thermodynamic Properties of Lithium by First-principles and Quasi-harmonic Debye Model

In this paper, the lattice parameter and bulk modulus of lithium(Li) at different pressures and temperatures are calculated by using the density functional theory method within the generalized gradient approximation(GGA).Through the quasi-harmonic Debye model, the thermodynamic properties of Li are predicted. The dependences of the normalized primitive cell volume V/V0 on pressure P, the variation of the thermal expansion coefficient α with pressure P and temperature T, as well as the dependences of the heat capacity Cv on pressure P and temperature T are obtained systematically in the ranges of 0~100 GPa and 0~2 000 K.

Quantitative and Qualitative Analysis of Bose—Einstein Condensation in Harmonic Traps

A simple and direct approach to handle summation is presented. With this approach, we analytically investigate Bose–Einstein condensation of ideal Bose gas trapped in an isotropic harmonic oscillator potential. We get the accurate expression of which is very close to (0.43% larger than) the experimental data. We find the curve of internal energy of the system vs. temperature has a turning point which marks the beginning of a condensation. We also find that there exists specific heat jump at the transition temperature, no matter whether the system is macroscopic or finite. This phenomenon could be a manifestation of a phase transition in finite systems.

Effect of Refiner Plate Bar Angle and Pulp Properties on the Low Consistency Refining Efficiency in Terms of Power Consumption

Power consumption is the energy source of the impact on fibers or pulp during low-consistency(LC)pulp refining,and the strength of refining affects refining quality and efficiency.The pulp properties,operating parameters,and bar parameters of the refiner plates are important parameters affecting refining efficiency,which can be defined as the ratio of net to total refining power.In this study,LC refining trials for pulps with different consistencies and fiber lengths were conducted using five isometric straightbar plates with different bar angles to explore the influences of the plate bar angle and pulp properties on the no-load power,impact capacity on fibers and refining efficiency.It was found that the no-load power of the LC refining process decreased with an increase in the plate bar angle while increased when pulp with higher consistency was refined under the same refining conditions.However,the effect of pulp consistency on the no-load power can be neglected when refining is conducted using plates with larger bar angles.Meanwhile,a critical bar angle for straight-bar plates in LC refining may exist,which has the strongest impact on the pulp and highest refining efficiency under the same refining conditions.In addition,the impact capacity of the plate on the pulp and refining efficiency in LC refining can be enhanced by appropriately increasing the pulp consistency and average fiber length when the bar angle of the refiner plate with a sector angle of 40°is less than 30°.Therefore,the efficiency and power consumption of the LC refining process can be adjusted by optimizing the pulp consistency and bar parameters of the refining plates.

LLM-105的分子间相互作用和热力学性质

应用第一性原理可以计算含能材料0 K下的结构和物理性质,但温度效应的缺失通常会导致计算数据与实验结果产生偏差.同时,与温度相关的热力学参数是含能材料在宏观和介观尺度下建模的关键输入.为此,本文以高能低感炸药1-氧-2,6-二氨基-3,5-二硝基吡嗪(LLM-105)为研究体系,基于准简谐近似,采用色散修正的密度泛函理论研究温度加载下LLM-105的分子间相互作用和热力学性质.晶格参数和热膨胀系数的演化表明LLM-105分子间相互作用具有强烈的各向异性,其中b轴方向(分子层间)的膨胀率远高于ac平面(分子层内).Hirshfeld表面及其指纹图分析进一步证实LLM-105的分子间相互作用主要取决于O···H构成的氢键.结合Mulliken布居数和结构分析,温度加载下氢键相互作用的变化可诱发硝基旋转,并使得C—NO_(2)键的强度明显减弱,为高温分解反应的触发键提供了理论依据.此外,本文计算了等容和等压条件下的热容、熵以及等温和绝热条件下的体模量等基础热力学参数.其中绝热条件下的体模量与实验值吻合,同时体模量随温度的演化反映了LLM-105在温度加载下的软化行为.上述理论研究可用于构建含能材料在介观和宏观尺度下的模型,也为测量原子分子水平下的热力学性质提供了重要的参考价值.

基于正交试验的杯形柔轮结构优化设计

文中针对柔轮结构设计中寿命与承载能力差、易失效等问题,首先对柔轮进行参数化建模,然后基于有限元分析软件对在波发生器装配下的柔轮进行静力学分析,以柔轮长度、壁厚、齿宽以及筒体圆角半径作为变量,柔轮最大等效应力作为优化目标设计正交试验,并通过极差分析对所选取的结构参数进行重新组合以达到结构优化目标。结果表明,通过正交试验得出各参数对空载状态下柔轮最大等效应力的影响程度为柔轮长度>齿宽>壁厚>筒底圆角半径,极差分析后对结构参数进行组合并进行建模仿真,使柔轮最大等效应力减小了32.43%,为柔轮的结构优化提供参考。

PIMS模型修正体积物性递归若干问题探讨

AspenPIMS(过程工业模型化系统)是美国艾斯本公司开发的一款功能强大的用于过程工业经济规划的工具软件,可为企业的生产经营活动提供决策依据,广泛应用于生产计划安排、原油优化采购、流程优化、效益测算、库存管理、瓶颈问题分析等方面。根据物料量类型分类,国内炼油厂PIMS模型主要为质量基模型。对质量基模型中常规体积物性递归存在的偏差问题进行了论述,并提出用体积物性原值与密度的商作为体积物性替代值来处理体积物性的方法,通过这个方法可以消除常规体积物性递归的偏差。

Mathematical Wave Functions and 3D Finite Element Modelling of the Electron and Positron

The wave/particle duality of particles in Physics is well known. Particles have properties that uniquely characterize them from one another, such as mass, charge and spin. Charged particles have associated Electric and Magnetic fields. Also, every moving particle has a De Broglie wavelength determined by its mass and velocity. This paper shows that all of these properties of a particle can be derived from a single wave function equation for that particle. Wave functions for the Electron and the Positron are presented and principles are provided that can be used to calculate the wave functions of all the fundamental particles in Physics. Fundamental particles such as electrons and positrons are considered to be point particles in the Standard Model of Physics and are not considered to have a structure. This paper demonstrates that they do indeed have structure and that this structure extends into the space around the particle’s center (in fact, they have infinite extent), but with rapidly diminishing energy density with the distance from that center. The particles are formed from Electromagnetic standing waves, which are stable solutions to the Schrödinger and Classical wave equations. This stable structure therefore accounts for both the wave and particle nature of these particles. In fact, all of their properties such as mass, spin and electric charge, can be accounted for from this structure. These particle properties appear to originate from a single point at the center of the wave function structure, in the same sort of way that the Shell theorem of gravity causes the gravity of a body to appear to all originate from a central point. This paper represents the first two fully characterized fundamental particles, with a complete description of their structure and properties, built up from the underlying Electromagnetic waves that comprise these and all fundamental particles.

Basic physical, acoustic properties, and in vitro ultrasound imaging enhancement of the lipid-coated microbubbles

Aim To research on a stable microbubble with good acoustic properties and excellent imaging enhancing effect, and to make it to be a promising agent for the enhancement of ultrasound imaging in the ultrasound diagnosis of cardiovascular system diseases. Methods The morphology, size and zeta potential of lipid-coated microbubbles （LCM）, the acoustic properties of backscatter, and the second harmonic scatter of LCM were determined. Furthermore, the relationship between the concentrations and the amplitude values of the second harmonic was investigated by testing the intensities of the second harmonic at different concentrations. The imaging effect of LCM was also studied in vitro. Results The mean diameter of LCM was 3.38 μm with 95% of the bubbles under 5 μm. The scatter signal generated by microbubbles was observed under different concentrations in the bistatic modes while the position of transmitting transducer and receiving transducer was orthogonal. The intensity of the second harmonic scatter fell with the decrease of microbubble concentration. The increase rate of the second harmonic amplitude values generated by the microbubbles versus that by physiological saline was linear with the natural logarithm of bubble concentrations. The LCM could enhance the ultrasound image of thrombus. Conclusion The LCM exhibited good physical state and acoustic properties, which could increase the imaging quality.

面向烟草工业谐波柔轮力学性能仿真

谐波减速器因其精密传动的特性,广泛应用于精密日用电器制造、机器人等多个领域中。本文以烟草成品入库机械手关节处谐波减速器关键技术为出发点,对机械手易损件谐波柔轮进行力学性能仿真。通过SOLIDWORKS软件对谐波减速器进行三维建模,基于ANSYS与Hyper Mesh联合仿真,真实模拟谐波减速器的从装配到工作的全过程,求解了谐波柔轮在全过程中的变形与应力;以柔轮各截面为分析对象,基于变形曲线、应力分布曲线、变形云图,找出柔轮易损点;因柔轮为回转结构,势必存在周向与轴向的形变,故柔轮存在偏转与翘曲,根据变形分析,得出波发生器、柔轮筒体、轮齿改进设计参数,进一步提高谐波减速器的啮合传动性能。

Time-energy properties of an attosecond extreme ultra-violet pulse

The time-energy properties of high-order harmonic generation （HHG） are calculated for a linearly polarized 7- fs laser pulse with different carrier-envelope phases （CEPs）. The quantum trajectory paths that contribute to an as （1 as=10^-18 s） pulse in HHG are identified. The laser-duration dependence and the CEP dependence of HHG energy property are investigated. The study shows that an as extreme ultra-violet （XUV） pulse can be selected from HHG spectrum near cut-off energy with a bandpass optical filter. The theoretical prediction of the pulse duration is proportional to bandwidth. Analysis suggests that a measured narrowband as XUV pulse may consist of instantaneous shorter pulses each dependent on laser pulse duration, intensity, and CEP. These information can be used as references for producing, selecting, improving and manipulating （timing） as pulses.

ANGULAR SPECTRUM PROPERTY OF SPONTANEOUS EMISSION IN A TWO-DIMENSIONAL UNDULATOR FREE-ELECTRON LASER

The angular spectrum of spontaneous emission in a two-dimensional undulator free-electron laser is analyzed theoretically. Numerical calculation shows that the 3-th harmonic spontaneous emission power density can be greatly enhanced by using a two-dimensional undulator, for which l=s, so the harmonic number can be selected by selecting l. Therefore, the higher harmonic operation of a free-electron laser can be realized selectively.

Electronic Structures and Optical Properties of HgGa_2X_4 (X=S,Se,Te)Semiconductors

The first-principles density functional calculations are performed to study the geometries and electronic structures of HgGa2X4（X = S,Se,Te） semiconductors with defect chalcopyrite structures,and the optical properties of all crystals are investigated systematically.The results indicate that these compounds have similar band structures and the band gap decreases from S to Se to Te.For the linear optical properties,three crystals show good light transmission in the IR and part visible regions,and in particular,HgGa2S4 and HgGa2Se4 crystals possess moderate birefringence.For the nonlinear optical properties,these crystals have stronger second harmonic generation（SHG）,and are theoretically predicted to have larger second-order static SHG coefficients（ 30 pm/V）.The SHG of HgGa2X4（X = S,Se,Te） semiconductors can be attributed to the transitions from the bands near the top of valence band derived from X（X = S,Se,Te） p states to the unoccupied bands contributed by the p states of Ga atoms.Our results indicate that the HgGa2S4 and HgGa2Se4 compounds are good candidates for nonlinear optical crystals in the IR region.

Nonlinear optical properties of novel H-shaped chromophores

Novel and effective H-shaped chromophores were doped into polymethyl methacrylate （PMMA） to form guest-host polymer thin films. The measurement results of Maker fringe method show that the polymer thin films containing the H-shaped chromophores as a guest exhibit high second harmonic coefficients （d33） compared with other two-dimensional chromophores.

First-principles calculations on the elastic and thermodynamic properties of NbN

The elastic and thermodynamic properties of NbN at high pressures and high temperatures are investigated by the plane-wave pseudopotential density functional theory （DFT）. The generalized gradient approximation （GGA） with the Perdew-Burke Ernzerhof （PBE） method is used to describe the exchange-correlation energy in the present work. The calculated equilibrium lattice constant a0, bulk modulus B0, and the pressure derivative of bulk modulus B~ of NbN with rocksalt structure are in good agreement with numerous experimental and theoretical data. The elastic properties over a range of pressures from 0 to 80.4 GPa are obtained. Isotropic wave velocities and anisotropic elasticity of NbN are studied in detail. It is indicated that NbN is highly anisotropic in both longitudinal and shear-wave velocities. According to the quasi-harmonic Debye model, in which the phononic effect is considered, the relations of （V - Vo）/Vo to the temperature and the pressure, and the relations of the heat capacity Cv and the thermal expansion coefficient α to temperature are discussed in a pressure range from 0 to 80.4 GPa and a temperature range from 0 to 2500 K. At low temperature, Cv is proportional to T3 and tends to the Dulong Petit limit at higher temperature. We predict that the thermal expansion coefficient α of NbN is about 4.20 × 10-6/K at 300 K and 0 GPa.

First-principles calculations of structural and thermodynamic properties of β-PbO

We employed ab-initio calculations to investigate the structural and thermodynamic properties of Massicot or orthorhombic phase of PbO named β-PbO using the projector augmented-wave（PAW） method within the generalized gradient approximation（GGA）. The temperature and pressure dependence of bulk modulus, heat capacity at constant pressure and constant volume, entropy, thermal expansion coefficient and Grüneisen parameter were discussed. Accuracy of two different models, the Debye and Debye-Grüneisen which are based on the quasi-harmonic approximation（QHA） for producing thermodynamic properties of material were compared. According to calculation results, these two models can be used to designate thermodynamic properties for β-PbO with sensible accuracy over a wide range of temperatures and pressures, and our work on the properties of this structure will be useful for more deeply understanding various properties of this structure.

First principle calculation of elastic and thermodynamic properties of stishovite

Using ab initio plane-wave pseudo-potential density functional theory method, the elastic constants and band structures of stishovite were calculated. The calculated elastic constants under ambient conditions agree well with previous experimental and theoretical data. C13, C33, C44, and C66 increase nearly linearly with pressure while C11 and C12 show irregularly changes with pressure over 20 GPa. The shear modulus （Cll-C12）/2 was observed to decrease drastically between 40 GPa and 50 GPa, indicating acoustic mode softening in consistency with the phase transition to CaC12-type structure around 50 GPa. The calculated band structures show no obvious difference at 0 and 80 GPa, being consistent with the high incompressibility of stishovite. With a quasi-harmonic Debye model, thermodynamic properties of stishovite were also calculated and the results are in good agreement with available experimental data.

Structural, Anisotropic and Thermodynamic Properties of Imm2-BCN

Structural, anisotropic, and thermodynamic properties of Imm2-BCN were studied based on density function theory with the ultrasoft psedopotential scheme in the frame of the generalized gradient approximation（GGA）. The elastic constants were confirmed that the predicted Imm2-BCN is mechanically stable. The anisotropy of elastic properties were also studied systematically. The anisotropy studies of Young＇s modulus, shear modulus, linear compressibility, and Poisson＇s ratio show that the Imm2-BCN exhibits a large anisotropy. Through the quasi-harmonic Debye model, the relations between the equilibrium volume V, thermal expansion α, the heat capacity C_V and CP, the Grüneisen parameter γ, and the Debye temperature Θ_D with pressure P and temperature T were also studied systematically.

调气思维论治肺系疾病

肺乃气脏,覆盖于五脏六腑之上,其所处位置最高,肺气贯通百脉流行于它脏。肺系疾病的发生、发展与气息息相关,其病机关键在于气的属性失调,气机运行不畅,从而导致肺气失调,宣发肃降失常。中医药在治疗肺系疾病时,从整体出发,调节气的属性,纠正人体之气的阴阳、功能、物质、脏腑属性的偏盛偏衰,令其舒和。该文秉着治病在于求本的原则,以治肺调气理论为指导思想,从宣降肺气、健运脾气、泻肝调气、温补肾气、振奋心气、通调腑气等方面入手,恢复并维持脏腑间的气机升降协调平衡,使邪出有路,机体恢复阴平阳秘之机。将调畅气机作为治疗肺系疾病的核心,以达“纠偏调衡”的目的,令气之升降出入有序、聚散转化有常、循行周身如环而无端,则肺病乃愈。