Effect of Wigner energy on the symmetry energy coefficient in nuclei

The nuclear symmetry energy coefficient(including the coefficient a_(sym)~((4)) of the I~4 term) of finite nuclei is extracted by using the differences of available experimental binding energies of isobaric nuclei.It is found that the extracted symmetry energy coefficient a_(sym)~*(A,I) decreases with increasing isospin asymmetry I,which is mainly caused by Wigner correction,since e_(sym)~* is the summation of the traditional symmetry energy e_(sym) and the Wigner energy ew.We obtain the optimal values J = 30.25±0.10 MeV,a_(ss)=56.18±1.25 MeV,a_(sym)~((4)) = 8.33±1.21 MeV and the Wigner parameter x= 2.38 ±0.12 through a polynomial fit to 2240 measured binding energies for nuclei with20 ≤ A ≤ 261 with an rms deviation of 23.42 keV.We also find that the volume symmetry coefficient J■ 30 MeV is insensitive to the value x,whereas the surface symmetry coefficient a_(ss) and the coefficient a_(sym)~((4)) are very sensitive to the value of x in the range 1≤x≤4.The contribution of the a_(sym)~((4)) term increases rapidly with increasing isospin asymmetry I.For very neutron-rich nuclei,the contribution of the a_(sym)~((4)) term will play an important role.     

现场激光能量计量技术的研究

由于激光能量计传感器的灵敏度与温度条件有关，在温差较大时，有的传感器灵敏度偏差可达到16%，因而在靶场、野外现场温度条件下，现有的激光能量计无法进行准确测试。为了解决这一问题，研制了一种新型的现场激光能量计。在现有激光能量计的基础上，通过选择相对透明、吸收层相对较厚(毫米量级)、热敏面不易损伤的激光吸收材料，对激光能量计内置温度传感器及数字处理电路进行了重新设计，满足了不同温度条件下现场能量测量的需求。     

光纤的能量传输特性及应用

着重分析了影响光纤传输能量以及光纤传输中造成能量损耗的因素。这些因素主要包括光纤材料、构造、光纤的折射率分布、光纤的长度和芯径、光纤的数值孔径和热效应以及耦合等。同时 ,结合激光二极管点火的实例 ,分析探讨了其背景和应用价值。结论是 :为了尽可能减少能量损耗、提高光纤输出的激光功率和激光功率密度 ,应当选取合适的激光工作波长、较小的光纤长度、较小的芯径和较小的数值孔径 ,应采用渐变折射率分布光纤 ,应减少弯曲与耦合     

干涉现象中能量叠加的实验研究

经典的波动理论与量子理论均分别对杨氏双缝干涉实验进行了解释。由于两个解释理论一个简单直观、一个复杂抽象,但两者结果一致,使得学生在学习中容易接受波动理论而排斥量子理论。文中通过实验观测了杨氏双缝干涉光场中能量传递与叠加的实际情况,结果显示实验实际情况与波动理论解释明显不相符合,而与量子理论解释完全相符。通过实验,使学生直观地看到波动理论的局限性,并加深学生对量子力学相关理论的理解。     

Distribution of components in single crystals grown from completely mixed melts of Hg1−xCdxTe and Pb1−xSnxTe systems

Summary A method is given to calculate the maximum compositional gradient in single crystals, grown by unidirectional solidification, of binary or pseudobinary materials. The calculation is based on the data obtained from the phase diagrams. Compositional gradients of HgTe-CdTe and PbTe-SnTe systems along the growth axis are shown.     

On the importance of zero-point effects in molecular level classical simulations of water

We discuss the fundamental difficulties involved in comparing energetic results obtained via classical simulations of bulk water with the observed values. Emphasis is placed on the difference between quantum and classical dynamics, and correction techniques, which can be used to emulate quantum effects in a classical system, are investigated. We present molecular dynamics simulation results for liquid water using the ‘Thole-type’ all atom polarizable water model, which has previously been shown to give reasonable results for both ice Ih and small water clusters. We employ expressions for the density of states power spectrum in the liquid in either atomic or rigid-body coordinates that are appropriate for rigid molecule simulations. It is demonstrated that the atomic power spectra can be written as a linear combination of the center of mass and rotational power spectra via the use of the ‘coupling matrix’ of linear coefficients. This approach allows us to introduce the concept of ‘fractional degrees of freedom’ (DOF) for nuclei in rigid molecule simulation. Within this framework, it is illustrated that in a rigid water molecule the oxygen and hydrogen atoms have 2.82 and 1.59 DOF, respectively (for the TIP4P geometry). Within our suggested approach, we finally demonstrate that Debye–Waller factors can be obtained from the coupling matrix and show that quantum corrections to the structure can be accounted for by raising the temperature of the system in a classical simulation by approximately 50°, a result consistent with previous suggestions.     

A Review of Key Technologies and Trends in the Development of Integrated Heating and Power Systems in Agriculture

Petroleum agriculture, characterized by mechanization and chemistry, is developing rapidly in China. However, petroleum agriculture has not only brought food safety problems, but also caused great obstacles to the sustainable development of society. In view of the disadvantages of oil agriculture, we provide an upgrading plan for energy systems in agriculture. This work can help reduce carbon emissions and improve food security. We introduce the most advanced technologies in Chinese agricultural development and the technical scope includes new agricultural energy power generation, agricultural energy use and the safe operation of agricultural energy systems. We describe the detailed data of agricultural bioenvironmental and energy engineering to clarify the level of agricultural energy efficiency in China. The overall conclusion of this paper is that the deep integration of agriculture and energy internet has become the development trend of agricultural energy systems.     

New developments in the multiscale hybrid energy density computational method

Further developments in the hybrid multiscale energy density method are proposed on the basis of our previous papers. The key points are as follows.(i) The theoretical method for the determination of the weight parameter in the energy coupling equation of transition region in multiscale model is given via constructing underdetermined equations.(ii)By applying the developed mathematical method, the weight parameters have been given and used to treat some problems in homogeneous charge density systems, which are directly related with multiscale science.(iii) A theoretical algorithm has also been presented for treating non-homogeneous systems of charge density. The key to the theoretical computational methods is the decomposition of the electrostatic energy in the total energy of density functional theory for probing the spanning characteristic at atomic scale, layer by layer, by which the choice of chemical elements and the defect complex effect can be understood deeply.(iv) The numerical computational program and design have also been presented.     

Analytical Method for Energy Spectra and Eigenstates in the Process of k-Photon Down-Conversion with Quantized Pump

In this paper, using the arguments of Wu et al. [Phys. Rev. Lett. 86 (2001) 2200] we analytically discussthe energy spectra and corresponding eigenstates for the process of k-photon down-conversion with quantized pump ina high-Q cavity by the aid of the computer programme. Remarkably, it is also shown that such a method can be usedfor solving numerically the equations in a much simpler manner than the previous ones.     

抛物量子线中极化子的激发态性质

研究抛物型量子线中极化子激发态的性质。采用线性组合算符法和Pekar变分法,导出了抛物量子线中强耦合和弱耦合两种情况下极化子的基态能量、第一内部激发能量、激发能和振动频率随量子线的约束强度的变化关系。数值计算结果表明:抛物型量子线中极化子的基态能量、第一内部激发能量、激发能和振动频率都随量子线约束强度的增强而增大,体现了量子线受限强度越大,相应的极化子的能量也越大。     

The negative energy density for a three-single-electron state in the Dirac field

We examine the energy density produced by a state vector which is the superposition of three single electron states in the Dirac field in the four-dimensional Minkowski spacetime. We derive the conditions on which the energy density can be negative. We then show that the energy density satisfies two quantum inequalities in the ultrarelativistic limit.     

Exchange and Coulomb interactions of two electrons in double ellipsoidal quantum dots

The present study seeks to scrutinize the interactions of two electrons on the electronic properties of double ellipsoidal quantum dots (EQD). In this regard, the effective-mass approximation within a perturbation scheme is used and the Coulomb and exchange energies of the two electrons ellipsoidal quantum dot are calculated for GaAs/GaAlAs/AlAs structure. The results showed that the Coulomb and exchange energies depend not only on the thickness of the intermediate layer but also on the ellipticity constant.     

Potential energy surfaces of ozone in the ground state

Equilibrium parameters of ozone, such as equilibrium geometry structure parameters, force constants and dissociation energy are presented by CBS-Q {\it ab initio} calculations. The calculated equilibrium geometry structure parameters and energy are in agreement with the corresponding experimental values. The potential energy function of ozone with a C离解能;空气;能量表面;地面ozone, potential energy surface, barrier, dissociation energyProject supported by the National Natural Science Foundation of China (Grant Nos~10376021 and 10676025), and the Scientific Research Fund of Sichuan Provincial Education Department, China (Grant No~2006A131).2006-10-08Equilibrium parameters of ozone, such as equilibrium geometry structure parameters, force constants and dissociation energy are presented by CBS-Q ab initio calculations. The calculated equilibrium geometry structure parameters and energy are in agreement with the corresponding experimental values. The potential energy function of ozone with a C2v symmetry in the ground state is described by the simplified Sorbie-Murrell many-body expansion potential function according to the ozone molecule symmetry. The contour of bond stretching vibration potential of an O3 in the ground state, with a bond angle （θ） fixed, and the contour of O3 potential for O rotating around O1-O （R1）, with O1-O bond length taken as the one at equilibrium, are plotted. Moreover, the potentials are analysed.     

有机/聚合物电致发光材料的能带结构及其在发光器件中的应用

测定了苯撑乙烯齐聚物、吡唑啉衍生物、钌配合物、铼配合物以及常用的有机染料与载流子传输材料等一百余种有机（包括有机小分子,配合物和聚合物）材料的能带来结构参数,探讨不同取代基对材料“能带”结构的影响。基于能带匹配的原则,同时考虑载流子迁移率匹配及各有机层间的厚度匹配,设计了不同结构的电致发光器件。研究表明,能带匹配、迁移率匹配以及厚度匹配是提高有机电致发光器件性能的重要依据。     

Analytical Method for Energy Spectra and Eigenstates in the Process of κ-Photon Down-Conversion with Quantized Pump

In this paper, using the arguments of Wu et al. [Phys. Rev. Left. 86 (2001) 2200] we analytically discuss the energy spectra and corresponding eigenstates for the process of κ-photon down-conversion with quantized pump in a high-Q cavity by the aid of the computer programme. Remarkably, it is also shown that such a method can be used for solving numerically the equations in a much simpler manner than the previous ones.     

飞秒激光等离子体通道传导能量特性的研究进展

基于强飞秒激光诱导等离子体通道的基本性质,分析了等离子体通道在传导电能和射频电磁能时的一些基本问题。综述了飞秒激光等离子体通道传输电能和电磁能方面的新概念和新技术,重点描述了该领域近几年所取得的一些理论及应用的最新成果。最后,展望了飞秒激光等离子体通道在传导能量技术领域中的发展趋势。     

声子和磁场对量子环中极化子性质的影响

采用求解能量本征方程、幺正变换和变分相结合的方法,研究声子和磁场对量子环中极化子性质的影响. 对KBr量子环的数值计算表明,电子或极化子的基态能量随量子环频率(或平均半径)的增大而增大,极化子基态能移随量子环频率的增大(或平均半径的减小)而减小,极化子中的平均声子数随量子环频率的增大(或平均半径的减小)而增大. 当有垂直磁场时,极化子基态能量和基态能移与外磁场及电子转动状态有关. 随着磁场强度的增大,基态能量出现简并且呈现非周期性振荡;能移随磁场强度的增大(或转动量子数绝对值的减小)而减小.     

Diffusion activation energy versus the favourable energy in two-order-parameter model:A molecular dynamics study of liquid Al

In the present work, we find that both diffusion activation energy E_a(D) and E_a(S^ex) increase linearly with pressure and have the same slope (0.022±0.001 eV/GPa) for liquid Al. The temperature and pressure dependence of excess entropy is well fitted by the expression -S^ex(T,P)/k_B=a(P)+b(P)T+c(P)exp(E_f/k_BT), which together with the small ratio of E_f/k_BT leads to the relationship of excess entropy to temperature and pressure, i.e. S^ex≈-cE_f/T, where c is about 12 and E_f (=Δ E-PΔV) is the favourable energy. Therefore, there exists a simple relation between E_a(S^ex) and E_f, i.e. E_a(S^ex)≈cE_f.     

Analysis of Energy Consumption in a Combined Microwave–hot Air Spouted Bed Drying of Biomaterial: Coffee Beans

In this study, an energy model based on the first law of thermodynamics is developed to evaluated energy efficiency and specific energy consumption. The influences of hot air temperature and initial weight of coffee beans on energy consumption are considered. Furthermore, a comparison between combined microwave–hot air spouted bed drying and hot air spouted bed drying methods on energy consumption is also investigated in detail. The results show that energy efficiency as well as energy consumption depends on hot air temperature, initial weight of coffee bean, and typical drying methods (combined microwave–hot air spouted bed and hot air spouted bed). The optimum drying condition is also achieved in this study.     

Screening of cosmological constant in non-local gravity

We discuss a possible mechanism to screen a cosmological constant in non-local gravity. We find that in a simple model of non-local gravity with the Lagrangian of the form, R+f(^□−1R)−2Λ$R+f({\square }^{-1}R)-2\Lambda$ where f(X)$f(X)$ is a quadratic function of X, there is a flat spacetime solution despite the presence of the cosmological constant Λ. Unfortunately, however, we also find that this solution contains a ghost in general. Then we discuss the condition to avoid a ghost and find that one can avoid it only for a finite range of ‘time’. Nevertheless our result suggests the possibility of solving the cosmological constant problem in the context of non-local gravity.