高功率808nm InGaAsP—GaAs分别限制结构的半导体激光器

介绍了研究分别限制结构ＩｎＧａＡｓＰ－ＧａＡｓ半导体激光器所得到的最新成果。利用引进的俄国技术，基于量子阱结构的ＩｎＧａＡｓＰ－ＧａＡｓ激光器，可用短时间液相外延技术制造。在ＧａＡｓ衬底上制成的ＩｎＧａＡｓＰ－ＧａＡｓ分别限制结构的激光器，主要参数如下：发射波入λ＝８０８ｎｍ，阈值电流密度Ｊ＝３００Ａ／ｃｍ＾２，对于条宽ω＝１００μｍ的激光器，连续功率为１－２Ｗ。     

用分子轨道法研究三乙基铝的结构与性质

采用从头算ＨＯＮＤＯ８．１程序分别选用ＳＴＯ－３Ｇ、６－３１Ｇ、６－２１Ｇ在ＨＦ水平上计算了三乙基铝的电子结构，用半经验分子轨道法ＭＯＰＡＣ６计算了三乙基铝的生成热等热力学性质     

MPEG-2先进音频编码(AAC)的研究和软件仿真

ＭＰＥＧ－２ＡＡＣ是ＩＳＯ／ＩＥＣ ＭＰＥＧ组织继 ＭＰＥＧ－１、ＭＰＥＧ－２音频编解码标准后,制定 的最新国际标准（ＩＳＯ／ＩＥＣ １３８１８－７）,在６４ｋｂｐｓ／每声道低码率时能提供全透明音质。本文对其编 解码算法进行了简要介绍。论文作者对ＭＰＥＧ－２ＡＡＣ进行了软件仿真,文中介绍了仿真结果,仿 真时对ＡＡＣ标准所附编码范例中的一些不妥之处,作了改进,文中列举了６方面的修正。     

电热蒸发－电感耦合等离子体原子发射光谱（ETV－ICP－AES）的基体效应研究

本文研究了电热蒸发电感耦合等离子体原子发射光谱（ＥＴＶ－ＩＣＰ－ＡＥＳ）中氯化物、高氯酸等产生的干扰，并且与无火焰石墨炉原子吸收（ＧＦＡＡＳ）中这些基体的干扰作了比较，认为ＥＴＶ－ＩＣＰ－ＡＥＳ的干扰比ＧＦＡＡＳ干扰小。本文还对这两种方法中干扰的差异作了一些探讨。     

MPEG-2先进音频编码(AAC)的研究和软件仿真

ＭＰＥＧ－２３ＡＡＣ是ＩＳＯ／ＩＥＣＭＰＥＧ组织继ＭＰＥＧ－１,ＭＰＥＧ－２音频编解码标准后,制定的最新国际标准（ＩＳＯ／ＩＥＣ１３８１８－７）在６４ｋｂｐｓ／每声道低码率时能提供全透明音质,本文对其编解码算法进行了简要介绍,论文作者对ＭＰＥＧ－２ＡＡＣ进行了软件仿真,文中介绍了仿真结果,仿真时对ＡＡＣ标准所附编码范 中的一些不妥之处,作了改进,文中列举了６方面的修正。     

电热蒸发—电感耦合等离子体原子发射光谱（ETV—ICP—AES）的基体…

本文研究了电热蒸发电感耦合等离子体原子发射光谱（ＥＴＶ－ＩＣＰ－ＡＥＳ）中氯化物，高氯酸等产生的干扰，并且与无火焰石墨炉原子吸收（ＧＦＡＡＳ）中这些基体的干扰作了比较，认为酸等产生的干扰，并且与无火焰石墨炉原子吸收（ＧＦＡＡＳ）中这些基体的干扰作了比较，认为ＥＴＶ－ＩＣＰ－ＡＥＳ的干扰比ＧＦＡＡＳ干扰小。本文还对这两种方法中干扰的差异作了一些探讨。     

在小硅化物SiX^m（X=Be,B,C,N,O,F,Ne,m=～4—＋2）中分子成…

此文用从头计算法，在ＨＦ，ＭＰ２，ＭＰ３水平下，使用基组６－３１Ｇ，６－３１＋Ｇ对ＳｉＯ的等电子分析ＳｉＸ＾ｍ（Ｘ＝Ｂｅ，Ｂ，Ｃ，Ｎ，Ｆ，Ｎｅ，ｍ＝－４～＋２）进行了几何优化，并计算了相应的平衡几何构型下的振动频率，对ＳｉＯ分子，使用ＱＣＩＳＤ（Ｔ）方法考虑了不同水平下的电相关效应，并考虑了不同其函数６－３１＋Ｇ和６－３１１＋Ｇ的影响。计算结果表明，所有分子的势能曲线都有稳定的极小值，并且键长与频     

Pb的类Fe、Co、Ni、Cu、Zn离子(Pb~(52 )-Pb~(56 ))能级和跃迁的相对论计算

采用相对论多组态平均能级模型（ＧＲＡＳＰ２－ＡＬ），计算了Ｐｂ的类Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ离子（Ｐｂ５２＋－Ｐｂ５６＋）的精细结构能级、跃迁波长、自发辐射跃迁几率、受激辐射跃迁几率和振子强度。波长的计算结果与实验值和文献的计算结果进行了比较     

NⅢ—ArⅩⅣ离子的双电子激发六重态跃迁的理论计算

根据相对论多组态理论，采用ＧＲＡＳＰ２（１９９２）程序计算了ＮⅢ—ＡｒⅩⅣ的１ｓ２ｓ２ｐ３６Ｓ０－１ｓ２ｓ２ｐ２３ｄ６Ｐ跃迁精细结构，计算的波长值与Ｊ．Ｈ．Ｂｌａｎｋｅ［１］等人的计算值和实验值进行了比较，并为六重态离子谱线辨识提供了有益的参考。     

PGBs对高能e~＋e~－湮没产生顶夸克对的单圈量子效应

在一代Ｔｅｃｈｎｉｃｏｌｏｒ（ＴＣ）模型中计算了ＰＧＢｓ（ＰｓｅｕｄｏＧｏｌｄｅｎｓｔｏｎｅＢｏｓｏｎｓ）对高能ｅ＋ｅ－→ｔｔ过程的单圈量子效应．给出了重整化的形状因子和矩阵元．计算了ＰＧＢｓ对总截面前后不对称参数ＡＦＢ和左右不对称参数ＡＬＲ的虚贡献，结果表明选取适当的参数值，新物理对以上可测量的贡献最大分别可达：－１２．３％、－３．３％和－１１．７％．在下一代对撞机上这一理论结果能为ＴＣ理论打开实验的窗口．同样的计算表明ＰＧＢｓ对ｅ＋ｅ－→ｂｂ过程的单圈贡献小于－１．０％．     

Calculated equation of state of al, cu, ta, mo, and W to 1000 GPa

Calculated Hugoniots and 293-K isotherms at pressures up to 1 TPa (10 Mbar) for the five reference metals Al, Cu, Ta, Mo, and W are reported using the classical mean-field approach where both the cold and the thermal parts of the Helmholtz free energy are derived entirely from the 0-K total energies and electronic density of states calculated with the full-potential linearized augmented plane wave method within the generalized gradient approximation to exchange correlational functional. Our approach permits efficient computation and invokes no empirical parameters. Both the experimental Hugoniots and 293-K isotherms are reproduced excellently.     

Solid state electrical conductivity and thermal degradation studies on some phenothiazine derivatives

Electrical conductivity and thermal degradation studies of promethazine hydrochloride (PH); 2-chlorophenothiazine (CP); diethazine hydrochloride (DH) and trifluoperazine dihydrochloride (TFP) are reported. The activation energies are evaluated based on their electrical conductivity study conducted over the temperature range 30-150 °C. These energies for PH, CP, DH and TFP are found to be 0.86, 1.02, 0.68 and 1.08 eV, respectively. The materials are analyzed for the kinetic parameters like the activation energies for decomposition and the Arrhenious pre-exponential factors in their pyrolysis region using Broido's, Coats-Redfern and Horowitz-Metzger methods. Using these factors and the standard equations thermodynamic parameters such as enthalpy, entropy and free energies are calculated. Thermogravimetric study on these phenothiazine derivatives in air indicated that their stabilities are in the order CP>TFP>PH >DH.     

First-principles study of the anisotropic thermal expansion of hcp metals Be and Y

A first-principles study of the anisotropic thermal expansion of hcp metals Be and Y is reported. According to quasiharmonic approximation, the phonon spectra were computed at a set of lattice parameters using the pseudopotential plane wave method with the local density approximation in the framework of the density functional perturbation theory. The free energies were obtained according to the calculated phonon spectra and thermal properties such as specific heat at constant volume (pressure) were calculated. The electronic contribution to specific heat was found important to metal Y not only at very low temperature but also over room temperature. The calculated results are in good agreement with available experimental data in a wide range of temperature.     

Giant dipole resonance and shape transitions in warm and rapidly rotating nuclei

We discuss the shape transitions in few medium heavy-mass nuclei with emphasis on low-temperature behaviour of the giant dipole resonance (GDR) observables. We employ a macroscopic approach towards GDR in which the GDR observables are related to the nuclear shapes. Shape calculations were done using the cranked Nilsson-Strutinsky method (CNSM) extended to finite temperature. Thermal shape fluctuations are computed with free energies calculated employing Landau parameterization as well as those calculated exactly (without using parameterizations) at given spin and temperature. The results obtained are confronted with the experimental data wherever available. Our study reveals that if the fluctuations are treated properly, then, in spite of thermal fluctuations, GDR observables could very well reflect the shape transitions at low temperature.     

高温稠密气态混合物质压强的计算

 基于含温有界相对论自洽场平均原子模型,计算了高温稠密条件下气态混合物的压强。通过求解相对论Dirac方程给出有界原子的电子波函数和轨道能量。电子在各单电子轨道上的平均占据数服从Fermi-Dirac分布。以铝、铝镁混合物、铁和高能炸药HMX（奥克托金）为算例,计算了在一些温度密度点下的压强并给出了分析。     

Temperature dependence of volume and surface symmetry energy coefficients of nuclei

The thermal evolution of the energies and free energies of a set of spherical and near-spherical nuclei spanning the whole periodic table are calculated in the subtracted finite-temperature Thomas–Fermi framework with the zero-range Skyrme-type KDE0 and the finite-range modified Seyler–Blanchard interaction. The calculated energies are subjected to a global fit in the spirit of the liquid-drop model. The extracted parameters in this model reflect the temperature dependence of the volume symmetry and surface symmetry coefficients of finite nuclei, in addition to that of the volume and surface energy coefficients. The temperature dependence of the surface symmetry energy is found to be very substantial whereas that of the volume symmetry energy turns out to be comparatively mild.     

A new Monte Carlo power method for the eigenvalue problem of transfer matrices

We propose a new Monte Carlo method for calculating eigenvalues of transfer matrices leading to free energies and to correlation lengths of classical and quantum many-body systems. Generally, this method can be applied to the calculation of the maximum eigenvalue of a nonnegative matrix  such that all the matrix elements of Â^k are strictly positive for an integerk. This method is based on a new representation of the maximum eigenvalue of the matrix  as the thermal average of a certain observable of a many-body system. Therefore one can easily calculate the maximum eigenvalue of a transfer matrix leading to the free energy in the standard Monte Carlo simulations, such as the Metropolis algorithm. As test cases, we calculate the free energies of the square-lattice Ising model and of the spin-1/2XY Heisenberg chain. We also prove two useful theorems on the ergodicity in quantum Monte Carlo algorithms, or more generally, on the ergodicity of Monte Carlo algorithms using our new representation of the maximum eigenvalue of the matrixÂ.     

Application of Lie transform perturbation method for multidimensional non-Hermitian systems

Three-dimensional non-Hermitian systems are investigated using classical perturbation theory based on Lie transformations. Analytic expressions for total energy in terms of action variables are derived. Both real and complex semiclassical eigenvalues are obtained by quantizing the action variables. It was found that semiclassical energy eigenvalues calculated with the classical perturbation theory are in very good agreement with exact energies and for certain non-Hermitian systems second-order classical perturbation theory performed better than the second-order Rayleigh–Schroedinger perturbation theory.     

Anharmonic Properties of Aluminum from Direct Free Energy Interpolation Method

We compare the direct free energy interpolation(DFEI) method and the quasi-harmonic approximation(QHA) in calculating of the equation of states and thermodynamic properties of prototype Al. The Gibbs free energy of Al is calculated using the DFEI method based on the high-temperature phonon density of states reduced from classical molecular dynamics simulations. Then, we reproduce the thermal expansion coefficients, the specific heat, the isothermal bulk modulus of Al accurately. By comparing the results from the DFEI method and the QHA, we find that the DFEI method is indeed more accurate in calculating anharmonic properties than the QHA.     

热辐射对热团簇衰变率和丰度的影响

本文量化了辐射冷却对单分子衰变速率、热簇以及非特定激发能量的分子的影响.检测出两种不同的区域,可以通过发射光子的能量大小进行定义,并根据光子发射速率常数和颗粒的热性质确定它们之间的边界.此外,通过丰度光谱计算了相当于小光子能量的连续冷却情况.两种不同区域分别是连续性冷却和单分子衰变的单光子猝灭.辐射效应通过重新定义每个单独的团簇用于进行蒸发的时间进行参数化,可用有效辐射时间常数来表示.