共查询到20条相似文献,搜索用时 125 毫秒
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建立了光致变色二芳基乙烯样品光致各向异性动力学的理论模型.计算了在线偏振光激发下,二芳基乙烯分子数密度、光致二向色性和光致双折射随时间(曝光量)的动态变化曲线.结果表明,随着激发曝光量的增加,二芳基乙烯呈色态分子数密度不断下降直至饱和,光致各向异性随曝光量增加先增加,达到最大之后开始下降,最佳曝光量为260J/cm2.利用正交偏振检测方法测量了反映材料各向异性的探测光透过率动力学曲线,并与理论计算结果进行了比较,二者基本相符.
关键词:
光致各向异性
二芳基乙烯
动态特性
最佳曝光量 相似文献
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n维经典非理想气体的物态方程与热力学函数 总被引:3,自引:3,他引:0
求出了n维经典非理想气体的物态方程和热力学函数.由London理论得出了维数n(n<6)不同时的经典非理想气体的物态方程形式基本一样,且与能谱关系无关的结论;当维数n≥6时,如果仍用London理论,巨配分函数发散,此时物态方程及热力学函数将无意义.事实上只要使用刚性球模型,无论是否使用London理论,总存在一个维数n,当维数大于n时巨配分函数发散. 相似文献
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在对Grüneisen系数高温高压特性不作任何假设的前提下,由冲击雨贡纽数据直接确定了材料零温零压体积、等温体模量及其对压力的一阶偏导。基于上述参数,计算了两种常用压标材料金和铂压缩比至0.5~0.6的0 K物态方程,并通过相应的热压修正得到了金和铂的室温等温物态方程。计算结果与准静水压条件下静高压实验结果具有非常好的吻合性,缩小了早期不同金和铂压标之间的差异。独立来源实验数据和理论计算结果的交叉检验表明,金和铂的室温等温物态方程计算结果可以用于今后静高压实验的压标。 相似文献
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从二维系统的Kosterlitz-Thouless (KT) 相变理论出发,在关联长度中引入热激活能和平均钉扎高度,提出了修正的KT相变模型.该模型与库伦气体标度理论和Halperin-Nelson关系具有一致性.应用修正的KT相变模型研究磁场下Tl2Ba2CaCu2Ox(Tl-2212)薄膜电阻转变的标度行为,发现由电阻转变计算得到的平均钉扎高度与温度具有线性依赖关系,实验结果支持修正的KT相变模型.
关键词:
标度行为
各向异性超导体
电阻转变 相似文献
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The shock compression of a heterogeneous material is numerically simulated. The physical model used for the simulation is based on a layered model of a porous material and consists of a set of thin matrix plates with a known equation of state that are separated by filler layers also with a known equation of state. The model is intended to calculate the parameters (pressure, temperature, mass velocity) of shock compression of the matrix and the filler of heterogeneous materials during their one-dimensional shock compression in terms of a developed hydrodynamic code. The adequacy of the proposed model is tested on porous molybdenum during shock-wave loading to a pressure of 15–70 GPa and a temperature of 4000 K. 相似文献
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S.K. Srivastava S.K. Sharma K. Vinod V.S. Malik 《Journal of Physics and Chemistry of Solids》2008,69(4):1029-1032
In the present communication we have modified the earlier calculations for the compression dependence of entropy of MgO using recent experimental data and more accurate equation of state. We have estimated the thermal expansivity with the help of the Anderson–Isaak equation at different compressions and selected temperatures up to the melting temperature of the solid. P–V relationship and compression dependence of isothermal bulk modulus are computed with the help of the Stacey equation of state. The results have been compared with those recommended by Cynn et al. [J. Phys. Chem. 99/19 (1995) 7813]. It is found that the entropy decreases with increasing compression along an isotherm. 相似文献
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Ratnesh K. Shukla Carlos Pantano Jonathan B. Freund 《Journal of computational physics》2010,229(19):7411-7439
A novel finite-volume interface (contact) capturing method is presented for simulation of multi-component compressible flows with high density ratios and strong shocks. In addition, the materials on the two sides of interfaces can have significantly different equations of state. Material boundaries are identified through an interface function, which is solved in concert with the governing equations on the same mesh. For long simulations, the method relies on an interface compression technique that constrains the thickness of the diffused interface to a few grid cells throughout the simulation. This is done in the spirit of shock-capturing schemes, for which numerical dissipation effectively preserves a sharp but mesh-representable shock profile. For contact capturing, the formulation is modified so that interface representations remain sharp like captured shocks, countering their tendency to diffuse via the same numerical diffusion needed for shock-capturing. Special techniques for accurate and robust computation of interface normals and derivatives of the interface function are developed. The interface compression method is coupled to a shock-capturing compressible flow solver in a way that avoids the spurious oscillations that typically develop at material boundaries. Convergence to weak solutions of the governing equations is proved for the new contact capturing approach. Comparisons with exact Riemann problems for model one-dimensional multi-material flows show that the interface compression technique is accurate. The method employs Cartesian product stencils and, therefore, there is no inherent obstacles in multiple dimensions. Examples of two- and three-dimensional flows are also presented, including a demonstration with significantly disparate equations of state: a shock induced collapse of three-dimensional van der Waal’s bubbles (air) in a stiffened equation of state liquid (water) adjacent to a Mie-Grüneisen equation of state wall (copper). 相似文献
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Manoj Kumar 《Journal of Physics and Chemistry of Solids》2007,68(4):670-672
It is found that the Shanker formulation widely used in the literature to study the thermal expansion of solids (at constant pressure) works under the effect of pressure (at constant temperature) up to a limited range (≈30 kbar). Large deviations occur, when the pressure range is increased, demonstrating the failure of the relation under high pressure (at constant temperature). We, therefore, propose the modification in the formulation on an empirical basis. The modified relation is used to study the compression behavior of ionic solids viz. NaF, NaCl, NaBr and NaI crystals. The results obtained with the modified relation are compared with the experimental data in the light of the results obtained from Shanker formulation and Birch-Murnaghan equation of state. A good agreement between theory and experiment demonstrates the validity of the modification presented in the present note. 相似文献
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Mohammed H. E. Abu-Sei''leek 《原子核物理评论》2010,27(4):399-410
The ground state properties of 132Sn at equilibrium and at large compression are investigated,within the framework of the radially constrained spherical Hartree-Fock(CSHF)approximation.The delta resonance effects on the properties of neutron-rich double magic spherical nucleus,132Sn,in its ground state and the state under static compression are studied.The sensitivity of the nucleon size and Δ model spaces is investigated.At equilibrium,mixing between nucleon and Δ's in the largest model space of nine major nucleon shells plus 10 Δ orbitals was found.Expanding the nucleon model space has a larger effect on reducing the static compression modulus and softe-ning the nuclear equation of state than increasing the number of Δ states.It was found that the most of the increase in the nuclear energy generated under compression is used to create the massive Δ particles.For 132Sn nucleus under compression at 12 times the normal nuclear density,the excited nucleons to Δ's increased sharply up to 13% of the total number of constituents.This result is consistent with the values extracted from relativistic heavy-ion collisions.The single particle energy levels calculated and their behaviors under compression are examined too.A good agreement between results with effective Hamiltonian and the phenomenological shell model for the low lying single-particle spectra is obtained. 相似文献
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A. M. Molodets A. A. Golyshev A. S. Savinykh V. V. Kim 《Journal of Experimental and Theoretical Physics》2016,122(2):289-297
The physico-mechanical properties of amorphous glassy carbon are investigated under shock compression up to 10 GPa. Experiments are carried out on the continuous recording of the mass velocity of compression pulses propagating in glassy carbon samples with initial densities of 1.502(5) g/cm3 and 1.55(2) g/cm3. It is shown that, in both cases, a compression wave in glassy carbon contains a leading precursor with amplitude of 0.135(5) GPa. It is established that, in the range of pressures up to 2 GPa, a shock discontinuity in glassy carbon is transformed into a broadened compression wave, and shock waves are formed in the release wave, which generally means the anomalous compressibility of the material in both the compression and release waves. It is shown that, at pressure higher than 3 GPa, anomalous behavior turns into normal behavior, accompanied by the formation of a shock compression wave. In the investigated area of pressure, possible structural changes in glassy carbon under shock compression have a reversible character. A physico-mechanical model of glassy carbon is proposed that involves the equation of state and a constitutive relation for Poisson’s ratio and allows the numerical simulation of physico-mechanical and thermophysical properties of glassy carbon of different densities in the region of its anomalous compressibility. 相似文献
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Dewaele A Loubeyre P Occelli F Mezouar M Dorogokupets PI Torrent M 《Physical review letters》2006,97(21):215504
The compression curve of iron is measured up to 205 GPa at 298 K, under quasihydrostatic conditions in a diamond anvil cell. Above 150 GPa, the compression of this metal is significantly higher than previously measured under nonhydrostatic conditions. The same compression curve is also calculated ab initio and the deviation between experiment and theory is clearly established. A formulation of the equation of state of iron over a large pressure and temperature range, based on the current data and existing shock-wave data, is also proposed. Implications for the Earth's core are discussed. 相似文献
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C. Fortmann H. J. Lee T. Döppner R. W. Falcone A. L. Kritcher O. L. Landen C. Niemann S. H. Glenzer 《等离子体物理论文集》2012,52(3):186-193
We present a method to measure the adiabatic index of a material under shock compression by X‐ray Thomson Scattering. A beryllium target is symmetrically compressed by two counterpropagating shock waves that collide in the target center, producing super dense states of matter of up to 6 fold compression. We measure the density before and after the shock collision and solve the Hugoniot relations for colliding shocks to infer the adiabatic index. Our results indicate that the adiabatic index stays rather high even in the high compression regime. This agrees with a linear scaling model taken from the SESAME equation of state and shows that the adiabatic index becomes significantly different from the ratio of heat capacities in this strongly coupled plasma (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Dr. R. O. Davis 《Zeitschrift für Physik B Condensed Matter》1972,15(3):230-236
Expressions are derived to give entropy and temperature in a material which obeys the Mie-Grüneisen equation, based on the
assumption that both the Hugoniot pressure and the Grüneisen parameter may be expanded as infinite power series in strain.
The resulting equations are used to obtain specific expressions for isothermal compression and for isentropic release from
a Hugoniot state. A method is suggested for determining the Grüneisen parameter (as a function of strain) from isothermal
compression data. Certain limitations involving possible phase transitions are pointed out. 相似文献
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高温高压气体的状态方程与热力学性质 总被引:3,自引:2,他引:1
本文根据高温高压下气体分子要压缩的观点出发,提出了一个简单实用的高温高压气体状态方程,并用以研究和计算气体在高温高压下的热力学函数与性质. 相似文献