复合场场论和矢量为主(VMD)、赝矢流近似守恒(PCAC)、场流关系以及流代数的一些问题

本文应用复合场场论导出矢量为主、赝矢流近似守恒和一系列新的场流关系,以及场流组合的代数。表明能为这些不同领域的理论提供统一的理论基础。     

Circuit theory for full counting statistics in multiterminal circuits

We propose a theory that treats the current, noise, and, generally, the full current statistics of electron transfer in a mesoscopic system in a unified, simple, and efficient way. The theory appears to be a circuit theory of 2 x 2 matrices associated with Keldysh Green functions. We illustrate the theory by considering the big fluctuations of currents in various three-terminal circuits.     

电磁涨落场引起的反常自举电流的准线性估计

本文研究了电磁涨落场产生的反常自举电流,得到了在低等离子体碰撞频率下该电流的一些重要特征。我们将所得到的反常自举电流与新经典理论预言的结果进行了比较,并讨论了反常自举电流与实验观测之间的可能联系。     

Theory of dc currents in SIS junctions with anisotropic pairing symmetry

Using the scattering theory for superconductive tunneling systems, we formulate a theory for the dc current in a superconducting junction with unconventional anisotropic pairing symmetry. We find that the phase anisotropy of the unconventional superconductor has important effects on the quasi-particle dc tunneling current, leading to an effective phase-anisotropy-dependent order parameter and a strong abnormal current peak in the subgap structure of the tunneling current.     

Current noise in ac-driven nanoscale conductors

The theory for current fluctuations in ac-driven transport through nanoscale systems is put forward. By use of a generalized, non-Hermitian Floquet theory we derive novel explicit expressions for the time-averaged current and the zero-frequency component of the power spectrum of current fluctuations. A distinct suppression of both the zero-frequency noise and the dc current occurs for suitably tailored ac fields. The relative level of transport noise, being characterized by a Fano factor, can selectively be manipulated by ac sources; in particular, it exhibits both characteristic maxima and minima near current suppression.     

外腔半导体激光器用恒流源电路设计与实现

由于外腔半导体激光器系统中的核心部分——激光器受外界环境影响较大,在装配或工作中极易受到电压、电流和静电荷的影响而损坏.为减少由于电路不稳定产生的激光器损坏,在借鉴各种传统的恒流源电路实现方式的基础上,运用反馈恒流原理,慢启动慢关闭原理,利用场效应管特性,给出一种高准确度恒流电路实现方式.将此电路直接运用于中心波长1550 nm激光器作为驱动电路,工作稳定、输出电流受负载影响很小且输出准确度达到同行业先进水平.电流稳定达到0.01％以上.此电路实现方式简单,实用性较强,对整个电路做出了实验仿真和测试,很好地解决了由于驱动电流不稳造成的激光器损坏的问题.     

Current percolation and anisotropy in polycrystalline MgB(2)

The influence of anisotropy on the transport current in MgB(2) polycrystalline bulk samples and wires is discussed. A model for the critical current density is proposed, which is based on anisotropic London theory, grain boundary pinning, and percolation theory. The calculated currents agree convincingly with experimental data, and the fit parameters, especially the anisotropy, obtained from percolation theory agree with experiment or theoretical predictions.     

Point-splitting derivation of anomalous divergence for the spinor current

The anomaly for the divergence of the spinor current in the supersymmetric Yang-Mills theory is obtained by the point-splitting regularization method. The results agree with those of the lowest order perturbation theory. The anomaly is removed by redifinition of the gauge invariant conserved current.     

Resistive states of the composite superconductors at magnetic flux creep

The effect of magnetic flux creep on the formation of resistive states of the composite superconductors has been studied taking into account their self-heating. The obtained results have been compared with the calculations carried out using the existing thermal stabilization theory, which is based on the model of a stepwise transition from the superconducting to normal state. It has been shown that, over a wide range of the superconductor temperature, this model leads to overrated effective electric resistances of the composite. As a result of its stable self-heating, the notions on the critical current, which determine the maximum transport current and on the resistive transition temperature, the higher of which in the transport current begins dividing between the superconductor and matrix, a loss a physical sense at magnetic flux creep, are used in the existing thermal stabilization theory. As a result, the limits of the theory of thermal stabilization of the composite superconductors can be extended if the theory has been used to describe stable sates at currents, which are higher than the conditionally defined critical current of the composite.     

夫兰克-赫兹实验栅极电流的研究

测量了夫兰克赫兹实验中氩气管的经典线性伏安特性曲线,分别从栅极电流和板极电流的实验数据中反应出的氩原子第一激发能级量子化吸收的特性,并对量子吸收理论在实验中的体现加以探讨。     

Proper definition of spin current in spin-orbit coupled systems

The conventional definition of spin current is incomplete and unphysical in describing spin transport in systems with spin-orbit coupling. A proper and measurable spin current is established in this study, which fits well into the standard framework of near-equilibrium transport theory and has the desirable property to vanish in insulators with localized orbitals. Experimental implications of our theory are discussed.     

Graded parafermions

A graded generalization of the Z_k parafermionic current algebra is constructed. This symmetry is realized in the osp(1|2)/U(1) coset conformal field theory. The structure of the parafermionic highest-weight modules is analyzed and the dimensions of the fields of the theory are determined. A free field realization of the graded parafermionic system is obtained and the structure constants of the current algebra are found. Although the theory is not unitary, it presents good reducibility properties.     

自旋-轨道耦合系统中的自旋流定义

通常的自旋流定义在描述自旋-轨道耦合系统中的自旋输运是不完整的与非物理的。文章作者提出在这类系统中自旋流的恰当定义。新定义的自旋流克服了通常定义下的本质缺点，可通过实验直接观测。     

On definitions and assumptions in the dislocation theory for solid solutions

A recent paper criticized the standard treatment of Cottrell atmospheres, relevant to solid-solution hardening. We show that the treatment in current texts is correct within the standard assumptions of dislocation theory. Nonlinear treatments of the atmosphere are discussed. We also show that no current theory of such atmospheres includes complete nonlinear screening of the dislocation strain field.     

The Generalization of Chern-Simons Current and the Topological Tensor Current of <Emphasis Type="Italic">p</Emphasis>-Branes

To make the gauge field theory foundation of the topological current of p-branes introduced in our previous work, we present a novel topological tensor current in SO(N) gauge field theory. This non-Abelian gauge field tensor current is the straightforward generalization of the Chern-Simons topological current of strings. By making use of the SO(N) gauge potential decomposition theory and the φ-mapping topological current theory, it is proved that the p-brane is created at every isolated zero of the Clifford vector field \(\overrightarrow{\phi }(x)\) and the charges carried by p-branes are topologically quantized and labelled by the winding number of the φ-mapping.     

装备保障能力评估方法综述

装备保障能力评估是提升武器装备战备完好率的重要手段,能有效地促进装备保障能力建设的科学发展和部队战斗力的提升。论文首先介绍了装备保障能力相关理论的发展情况,整理了装备保障能力评估的基本思路,然后从多元统计理论、不确定性理论、多属性评估法、数据挖掘技术、交叉学科理论及组合模型等方面介绍了当前评估方法的发展现状,梳理和总结了各方法的建模基本思想并比较其优缺点,结合研究现状指出了评估理论存在的问题,最后对下一步研究方向进行了归纳。     

Born–Infeld–Chern–Simons theory: Hamiltonian embedding,duality and bosonization

In this paper we study in detail the equivalence of the recently introduced Born–Infeld self-dual model to the Abelian Born–Infeld–Chern–Simons model in 2+1 dimensions. We first apply the improved Batalin, Fradkin and Tyutin scheme, to embed the Born–Infeld self-dual model to a gauge system and show that the embedded model is equivalent to Abelian Born–Infeld–Chern–Simons theory. Next, using Buscher's duality procedure, we demonstrate this equivalence in a covariant Lagrangian formulation and also derive the mapping between the n-point correlators of the (dual) field strength in Born–Infeld–Chern–Simons theory and of basic field in Born–Infeld self-dual model. Using this equivalence, the bosonization of a massive Dirac theory with a non-polynomial Thirring type current–current coupling, to leading order in (inverse) fermion mass is also discussed. We also rederive it using a master Lagrangian. Finally, the operator equivalence between the fermionic current and (dual) field strength of Born–Infeld–Chern–Simons theory is deduced at the level of correlators and using this the current–current commutators are obtained.     

Knotted Topological Phase Singularities of Electromagnetic Field

In this paper, knotted objects (RS vortices) in the theory of topological phase singularity in electromagnetic field have been investigated in details. By using the Duan's topological current theory, we rewrite the topological current form of RS vortices and use this topological current we reveal that the Hopf invariant of RS vortices is just the sum of the linking and self-linking numbers of the knotted RS vortices. Furthermore, the conservation of the Hopf invariant in the splitting, the mergence and the intersection processes of knotted RS vortices is also discussed.     

The Theory of Ionization Waves in the Contracted Discharge of Noble Gases

Positive column plasma in noble gases at middle pressures is analysed for stability in the frames of the linear hydrodynamic theory. At critical values of pressure and current the discharge becomes unstable to radial contraction (contraction) and to wave disturbances of the type of current pinch constrictions (contraction ionization waves). Ionization waves in the contracted discharge are three-dimensional formations with electron concentration oscillations on the axis in the opposite phase with current pinch cross section. The discharge diffuse-recombination theory was used for analysing the problem of instability arising.     

Topological Excitation in Skyrme Theory

Based on the C-mapping topological current theory and the decomposition of gauge potential theory, we investigate knotted vortex lines and monopoles in Skyrme theory and simply discuss the branch processes （splitting, merging, and intersection） during the evolution of the monopoles.