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位场向下延拓的波数域迭代法及其收敛性 被引量:59
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作者 刘东甲 洪天求 +4 位作者 贾志海 李建设 陆三明 孙晓峰 徐世浙 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2009年第6期1599-1605,共7页
提出了位场向下延拓的波数域迭代法.对水平面上的位场观测值进行Fourier变换,得到其波谱.根据第一类Fredholm积分方程的空间域迭代解法,推导出计算向下延拓水平面上位场波谱的波数域迭代公式.在波数域中进行迭代,一直进行到相继两次迭... 提出了位场向下延拓的波数域迭代法.对水平面上的位场观测值进行Fourier变换,得到其波谱.根据第一类Fredholm积分方程的空间域迭代解法,推导出计算向下延拓水平面上位场波谱的波数域迭代公式.在波数域中进行迭代,一直进行到相继两次迭代近似解的差值最大绝对值小于给定的精度,或迭代达到给定的最大迭代次数.对这种迭代近似解进行Fourier逆变换,得到向下延拓的位场.数值计算结果表明:与空间域迭代法比较,这种波数域迭代法简单、快速,并有同样好的向下延拓效果.本文还证明了这种迭代法是收敛的,并给出了它的收敛特性和滤波特性. 展开更多
关键词 位场 向下延拓 积分方程 FOURIER变换 波数域 迭代法
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乌兰布和沙漠可能蒸散的研究 被引量:15
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作者 何炎红 田有亮 郭连生 《干旱气象》 2007年第2期61-66,共6页
在测定该区2000~2005年气象因子的基础上,分析研究了乌兰布和沙漠沙地可能蒸散的月变化特点,比较分析了应用Penman方程、Thornthwaite公式和Holdridge 3种方法计算的可能蒸散。结果指出Penman方程计算的可能蒸散和水面蒸发量具有显著... 在测定该区2000~2005年气象因子的基础上,分析研究了乌兰布和沙漠沙地可能蒸散的月变化特点,比较分析了应用Penman方程、Thornthwaite公式和Holdridge 3种方法计算的可能蒸散。结果指出Penman方程计算的可能蒸散和水面蒸发量具有显著的直线性相关,可应用Penman方程计算所得的可能蒸散评价该区的水分蒸发特点。研究指出可能蒸散月变化与月平均温度的变化基本一致,全年最大的月份是7~8月,全年累计可能蒸散量为3 041 mm。 展开更多
关键词 乌兰布和沙漠 可能蒸散 Penman方程
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鼎湖山人工松林生态系统蒸散力及计算方法的比较 被引量:12
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作者 闫俊华 周国逸 陈忠毅 《生态学杂志》 CAS CSCD 北大核心 2001年第1期5-8,17,共5页
Based on the consecutive measurement (1995-1997) of meteorology and microclimate of artificial Pinus forest in Mount Dinghu, we calculated the potential evapotranspiration by using four different methods to discuss th... Based on the consecutive measurement (1995-1997) of meteorology and microclimate of artificial Pinus forest in Mount Dinghu, we calculated the potential evapotranspiration by using four different methods to discuss the method which is fit for forest ecosystem. The results are given as follows.1) In terms of the enviromental conditions of forest ecosystem, we redefined some parameters in Penman equation and used it to calculate the potential evapotranspiration of artificial Pinus forest ecosystem in Mount Dinghu.Preliminary result is that Penman equation is worth spreading for calculating the potential evapotranspiration of forest ecosystem,compared with several other methods.2) The annual average potential evapotranspiration of the artificial Pinus forest in Mount Dinghu is 937.55 mm,according to Penman equation. It is 50% of the rainfall in the corresponding period. The highest mean monthly potential evapotranspiration is July and the lowest mean monthly potential evapotranspiration is January. This is completely consistent with the variations of temperature. 展开更多
关键词 鼎湖山 人工松林 生态系统 蒸散力
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圆环电荷的电势的几种算法及讨论 被引量:14
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作者 张之翔 《大学物理》 北大核心 2006年第8期7-10,共4页
用三种方法计算了均匀带电圆环的电势,并略加讨论.
关键词 均匀圆环电荷 电势 椭圆积分 拉普拉斯方程
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电渗流泵的机理分析 被引量:6
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作者 仲武 陈云飞 庄苹 《东南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2003年第3期307-311,共5页
以实现CPU的温度控制、提高微流体的流动速度为目标 ,对电渗流的机理进行了分析 .应用无网格算法对Laplace方程、Poisson Boltzmann方程、Navier Stokes方程进行数值求解 ,得到的数值仿真结果与解析近似解吻合较好 .对微直管内的微流体... 以实现CPU的温度控制、提高微流体的流动速度为目标 ,对电渗流的机理进行了分析 .应用无网格算法对Laplace方程、Poisson Boltzmann方程、Navier Stokes方程进行数值求解 ,得到的数值仿真结果与解析近似解吻合较好 .对微直管内的微流体的流动进行了仿真 ,再现了微流体流动的驱动过程 ,并讨论了微流体的流动速度与外加垂直电场的电势和ζ电势的相关性 .本文的数学模型不仅可以仿真几何形状简单的微直管内微流体的驱动过程 ,也可仿真几何形状复杂、ζ电势较大条件下的微直管内微流体的流动 。 展开更多
关键词 电渗流 纳维-司托克斯方程 无网格算法
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基于多对流参数的武汉地区雷电活动预报方法研究 被引量:13
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作者 余蓉 杜牧云 +1 位作者 杜九三 刘云鹏 《气象科技》 北大核心 2016年第2期269-274,共6页
利用2011—2013年6—8月291个样本武汉站的探空资料计算了20种与雷电活动有关的对流参数,经统计分析后发现多个对流参数与雷电活动具有显著的相关性;选取与雷电相关性较好的对流参数作为预报因子,并用多元线性回归方法建立雷电潜势预报... 利用2011—2013年6—8月291个样本武汉站的探空资料计算了20种与雷电活动有关的对流参数,经统计分析后发现多个对流参数与雷电活动具有显著的相关性;选取与雷电相关性较好的对流参数作为预报因子,并用多元线性回归方法建立雷电潜势预报方程,方程通过了α=0.05的显著性水平检验;使用2014年6—8月的观测数据进行预报效果检验,结果表明:雷电预报的命中率POD为82.6%,虚假报警率FAR为23.3%,临界成功指数CSI为63.3%。由此可见,该方法的建立对武汉市雷电天气的预报和预警具有参考价值和指示意义。 展开更多
关键词 雷电活动 对流参数 潜势预报 回归方程
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高均匀度磁场线圈的设计 被引量:12
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作者 张伟 《计量学报》 CSCD 北大核心 2010年第5期404-407,共4页
磁场线圈是标准磁场装置中重要的组成部分,其均匀性指标直接影响标准磁场装置的性能和复现水平。利用磁位的拉普拉斯方程式在球坐标下的解,对单个轴对称线圈产生的磁场进行数理分析后给出其磁场分布的一般特性,在此基础上给出典型的... 磁场线圈是标准磁场装置中重要的组成部分,其均匀性指标直接影响标准磁场装置的性能和复现水平。利用磁位的拉普拉斯方程式在球坐标下的解,对单个轴对称线圈产生的磁场进行数理分析后给出其磁场分布的一般特性,在此基础上给出典型的多段环形组合线圈的具体设计方法和实际的数值运算结果,最后结合实际应用给出两个高均匀度线圈的设计过程。 展开更多
关键词 计量学 高均匀度磁场线圈 磁位 拉普拉斯方程 磁场系数
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内充气体与外部膜材的共同作用理论模型 被引量:12
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作者 李鹏 杨庆山 《力学学报》 EI CSCD 北大核心 2013年第6期919-927,共9页
将充气膜结构内充气体假定为势流,推导得到速度势表示的内充气体小幅波动方程,并采用Galerkin法离散得到内充气体的有限元动力学方程.引入界面协调条件,建立了内充气体结点速度势与外部膜材结点位移的关系,然后联立薄膜动力方程和气体... 将充气膜结构内充气体假定为势流,推导得到速度势表示的内充气体小幅波动方程,并采用Galerkin法离散得到内充气体的有限元动力学方程.引入界面协调条件,建立了内充气体结点速度势与外部膜材结点位移的关系,然后联立薄膜动力方程和气体动力学方程得到充气膜系统内充气体与外部膜材的共同作用理论模型.在该理论模型基础上,建立了两类典型充气结构的数值模型进行分析,通过将数值结果与试验结果对比,验证了共同作用理论模型的准确性和合理性. 展开更多
关键词 充气膜结构 势流 内充气体 共同作用 动力方程
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基于pF Meter的土体冻结特征曲线研究 被引量:10
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作者 薛珂 杨明彬 +3 位作者 温智 张明礼 李德生 高樯 《中国公路学报》 EI CAS CSCD 北大核心 2018年第3期22-29,共8页
为解决冻土中土体冻结特征曲线(SFCC)长期以来只能通过经验模型间接推测获得,且土体冻结特征曲线(SFCC)与土水特征曲线(SWCC)间关系的相关研究也因技术手段制约而仅停留在理论假设阶段的问题,采用可直接用于极端负温条件下的pFMeter基... 为解决冻土中土体冻结特征曲线(SFCC)长期以来只能通过经验模型间接推测获得,且土体冻结特征曲线(SFCC)与土水特征曲线(SWCC)间关系的相关研究也因技术手段制约而仅停留在理论假设阶段的问题,采用可直接用于极端负温条件下的pFMeter基质势传感器,得到青藏红黏土、兰州粉土、细砂这3种不同粒径土体的冻结特征曲线,获得三者在冻结过程中未冻水数量与能量变化之间的规律;对过去冻土学研究中利用Clapeyron方程间接转换获得土体冻结特征曲线方法的可靠性进行试验验证;此外,针对不同粒径大小土体冻结特征曲线及土水特征曲线进行比较,并对以往冻土冻胀研究中将饱和冻土中冰晶等划为非饱和融土中气体的方法进行验证。结果表明:Clapeyron方程得到的冻结特征曲线与实际测定的冻结特征曲线基本一致,Clapeyron方程可用于土体冻结特征曲线的预测;冻结特征曲线与土水特征曲线虽在形态上具有一定的相似性,但由于冻结过程与脱湿过程土中相的不同所致的各相间界面力不同,导致其在数值上存在一定差异,且差值大小与土体平均粒径成反比,进而证明了被广泛用于冻土研究中的将冻土中冰晶体视作融土中气体来简化冻结过程中冰晶-液态水-土颗粒关系的方法并不合理,并从理论上阐述了其机理;相关研究成果可为后续研究冻胀过程中水分迁移机制与水分迁移驱动力提供相应的基础理论支撑。 展开更多
关键词 道路工程 土体冻结特征曲线 PF METER 冻土 基质势 未冻水含量 Clapeyron方程
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用微扰理论状态方程计算电解质水溶液的活度系数 被引量:6
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作者 李春喜 宋红燕 +1 位作者 李以圭 陆九芳 《化工学报》 EI CAS CSCD 北大核心 2001年第4期363-367,共5页
An equation of state for electrolyte aqueous solution is developed by treating the ion-ion electrostatic and ion-solvent molecule interactions with primitive MSA and perturbation theory, respectively. The effect of th... An equation of state for electrolyte aqueous solution is developed by treating the ion-ion electrostatic and ion-solvent molecule interactions with primitive MSA and perturbation theory, respectively. The effect of the dielectric constant on the ionic chemical potential and the calculation accuracy of ionic mean activity coefficients for 2∶1 and 1∶1 type halide aqueous solution are discussed.By taking ionic Pauling diameter as ionic hard sphere diameter for anions and treating the cation hard sphere diameter as ionic strength dependent, the equation can be used to calculate ionic activity coefficients in the moderate concentration range with good accuracy. 展开更多
关键词 微扰理论 势能函数 电解质溶液 状态方程 活度系数 密度
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New Exact Solutions and Conservation Laws to (3+1)-Dimensional Potential-YTSF Equation 被引量:10
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作者 ZHANG Li-Hua LIU Xi-Qiang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第3期487-492,共6页
Using the modified find some new exact solutions to Lie point symmetry groups and also get conservation laws, of the CK's direct method, we build the relationship between new solutions and old ones and the (3+1)-d... Using the modified find some new exact solutions to Lie point symmetry groups and also get conservation laws, of the CK's direct method, we build the relationship between new solutions and old ones and the (3+1)-dimensional potentiaial-YTSF equation. Baaed on the invariant group theory, Lie symmetries of the (3+1)-dimensional potential-YTSF equation are obtained. We equation with the given Lie symmetry. 展开更多
关键词 new exact solutions Lie point symmetry groups conservation laws (3+1)-dimensional potential-YTSF equation
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Solution for fractional potential KdV and Benjamin equations using the novel technique 被引量:6
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作者 P.Veeresha D.G.Prakasha +2 位作者 N.Magesh A.John Christopher Deepak Umrao Sarwe 《Journal of Ocean Engineering and Science》 SCIE 2021年第3期265-275,共11页
In this paper,we find the solutions for fractional potential Korteweg-de Vries(p-KdV)and Benjamin equations using q-homotopy analysis transform method(q-HATM).The considered method is the mixture of q-homotopy analysi... In this paper,we find the solutions for fractional potential Korteweg-de Vries(p-KdV)and Benjamin equations using q-homotopy analysis transform method(q-HATM).The considered method is the mixture of q-homotopy analysis method and Laplace transform,and the Caputo fractional operator is considered in the present investigation.The projected solution procedure manipulates and controls the obtained results in a large admissible domain.Further,it offers a simple algorithm to adjust the convergence province of the obtained solution.To validate the q-HATM is accurate and reliable,the numerical simulations have been conducted for both equations and the outcomes are revealed through the plots and tables.Comparison between the obtained solutions with the exact solutions exhibits that,the considered method is efficient and effective in solving nonlinear problems associated with science and technology. 展开更多
关键词 potential KdV equation q-Homotopy analysis method Fractional Benjamin equation Laplace transform Ginzburg-Landau equation Caputo fractional operator
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Mathematical Wave Functions and 3D Finite Element Modelling of the Electron and Positron
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作者 Declan Traill 《Journal of Applied Mathematics and Physics》 2024年第4期1134-1162,共29页
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 an... 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. 展开更多
关键词 ELECTRON POSITRON Wave Function Solution Electromagnetic Spin Mass Charge Proof Fundamental Particle Properties Quantum Mechanics Classical Physics Computer 3D Model Schrödinger equation RMS KLEIN GORDON Electric Magnetic Lorentz Invariant Hertzian Vector Point potential Field Density Phase Flow Attraction REPULSION Shell Theorem Ehrenfest VIRIAL Normalization Harmonic Oscillator
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On a nonlinear elliptic problem with critical potential in R^2 被引量:6
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作者 SHEN Yaotian YAO Yangxin HEN Zhihui 《Science China Mathematics》 SCIE 2004年第5期741-755,共15页
Consider the existence of nontrivial solutions of homogeneous Dirichlet problem for a nonlinear elliptic equation with the critical potential in R2. By establishing a weighted inequality with the best constant, determ... Consider the existence of nontrivial solutions of homogeneous Dirichlet problem for a nonlinear elliptic equation with the critical potential in R2. By establishing a weighted inequality with the best constant, determine the critical potential in R2, and study the eigenvalues of Laplace equation with the critical potential. By the Pohozaev identity of a solution with a singular point and the Cauchy-Kovalevskaya theorem, obtain the nonexistence result of solutions with singular points to the nonlinear elliptic equation. Moreover, for the same problem, the existence results of multiple solutions are proved by the mountain pass theorem. 展开更多
关键词 ELLIPTIC equation HARDY inequality critical potential MOUNTAIN PASS theorem.
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A-E equation of potential field transformations in the wavenumber domain and its application 被引量:7
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作者 Chai Yupu 《Applied Geophysics》 SCIE CSCD 2009年第3期205-216,299,共13页
A shift sampling theory established by author (1997a) is a generalization of Fourier transform computation theory. Based on this theory, I develop an Algorithm-Error (A-E) equation of potential field transformatio... A shift sampling theory established by author (1997a) is a generalization of Fourier transform computation theory. Based on this theory, I develop an Algorithm-Error (A-E) equation of potential field transformations in the wavenumber domain, which not only gives a more flexible algorithm of potential field transformations, but also reveals the law of error of potential field transformations in the wavenumber domain. The DFT0η η(0.5, 0.5) reduction-to-pole (RTP) technique derived from the A-E equation significantly improves the resolution and accuracy of RTP anomalies at low magnetic latitudes, including the magnetic equator. The law (origin, form mechanism, and essential properties) of the edge oscillation revealed by the A-E equation points out theoretically a way of improving the effect of existing padding methods in high-pass transformations in the wavenumber domain. 展开更多
关键词 potential field transformation Fourier transform shift sampling theory A-E equation DFT0η η(0.5 0.5) algorithm
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The Electromagnetic Operator of Mass
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作者 Hosam Mahmoud Maksoud 《Journal of Applied Mathematics and Physics》 2023年第10期3203-3211,共9页
Studying the source of particle properties is the most important goal for scientists, so it was necessary to use the means available to us, which is physical logic to study these properties. In this paper, you will ex... Studying the source of particle properties is the most important goal for scientists, so it was necessary to use the means available to us, which is physical logic to study these properties. In this paper, you will examine how the type of coordinates in which electromagnetic fields are distributed can have a role in detecting particle properties, specifically using the Riemann-Silberstein vector. Because electromagnetism it deals with electric and magnetic fields together for any electromagnetic sentence, and when we study it according to multiple coordinates and study its derivation by changing coordinates, we discover how the electromagnetic sentences are transformed from one particle to another. 展开更多
关键词 Electromagnetic potential Annihilation of Pairs Creating of Pairs Proca’s equation Dirac’s equation Riemann-Silberstein Vector
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Approximate Generalized Conditional Symmetries for the Perturbed Nonlinear Diffusion-Convection Equations 被引量:4
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作者 张顺利 屈长征 《Chinese Physics Letters》 SCIE CAS CSCD 2006年第3期527-530,共4页
The concept of approximate generalized conditional symmetry (A GCS) as a generalization to both approximate Lie point symmetry and generalized conditional symmetry is introduced, and it is applied to study the pertu... The concept of approximate generalized conditional symmetry (A GCS) as a generalization to both approximate Lie point symmetry and generalized conditional symmetry is introduced, and it is applied to study the perturbed nonlinear diffusion-convection equations. Complete classification of those perturbed equations which admit cerrain types of AGCSs is derived. Some approximate solutions to the resulting equations can be obtained via the AGCS and the corresponding unperturbed equations. 展开更多
关键词 PARTIAL-DIFFERENTIAL-equationS FUNCTIONAL VARIABLE SEPARATION INITIAL-VALUE PROBLEMS potential SYMMETRIES WAVE-equation REDUCTION CLASSIFICATION
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Limiting profile of blow-up solutions for the Gross-Pitaevskii equation 被引量:4
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作者 ZHU ShiHui ZHANG Jian LI XiaoGuang 《Science China Mathematics》 SCIE 2009年第5期1017-1030,共14页
This paper is concerned with the blow-up solutions of the Gross-Pitaevskii equation. Using the concentration compact principle and the variational characterization of the corresponding ground state, we obtain the limi... This paper is concerned with the blow-up solutions of the Gross-Pitaevskii equation. Using the concentration compact principle and the variational characterization of the corresponding ground state, we obtain the limiting profile of blow-up solutions with critical mass in the corresponding weighted energy space. Moreover, we extend this result to small super-critical mass case by the variational methods and scaling technique. 展开更多
关键词 Gross-Pitaevskii equation blow-up solution Bose-Einstein condensate harmonic potential concentration compact principle small super-critical mass 35B35 35Q53
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Approximate any 1-state solutions of the Dirac equation for modified deformed Hylleraas potential by using the Nikiforov—Uvarov method 被引量:5
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作者 H.Hassanabadi E.Maghsoodi +1 位作者 S.Zarrinkamar H.Rahimov 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第12期57-65,共9页
We investigate the spin and pseudospin symmetries of the Dirac equation under modified deformed Hylleraas potential via a Pekeris approximation and the Nikiforov-Uvarov technique. A tensor interaction of Coulomb form ... We investigate the spin and pseudospin symmetries of the Dirac equation under modified deformed Hylleraas potential via a Pekeris approximation and the Nikiforov-Uvarov technique. A tensor interaction of Coulomb form is considered and its degeneracy-removing role is discussed in detail. The solutions are reported for an arbitrary quantum number in a compact form and useful numerical data are included. 展开更多
关键词 Dirac equation spin symmetry pseudospin symmetry modified Hylleraas potential
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Makarov势的Dirac方程的束缚态解 被引量:6
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作者 张民仓 王振邦 《物理学报》 SCIE EI CAS CSCD 北大核心 2006年第12期6229-6233,共5页
给出了Makarov型标量势与矢量势相等条件下的Dirac方程的束缚态解.Dirac方程的角向方程用因子分解方法求解,在得出角向波函数的过程中,自然地得到了属于同一本征值的不同角向波函数间的递推操作.径向束缚态波函数用合流超几何函数表示,... 给出了Makarov型标量势与矢量势相等条件下的Dirac方程的束缚态解.Dirac方程的角向方程用因子分解方法求解,在得出角向波函数的过程中,自然地得到了属于同一本征值的不同角向波函数间的递推操作.径向束缚态波函数用合流超几何函数表示,束缚态的能量方程可由径向波函数满足的边界条件得到. 展开更多
关键词 Makarov势 DIRAC方程 束缚态 因子分解方法
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