The interaction of magnetic colloidal particles includes the interaction of colloidal particles and the interaction of the moment of magnetism.The interaction of the moment of magnetism is regard as perturbation.Accor...The interaction of magnetic colloidal particles includes the interaction of colloidal particles and the interaction of the moment of magnetism.The interaction of the moment of magnetism is regard as perturbation.According to the low density system of magnetic colloidal particles in water,a theoretic model is set up based on perturbation theory.The relations between internal energy,specific heat of magnetic colloidal particles system and temperature,density of colloidal particles are calculated.The calculated results are useful in explaining the magnetic memory effect.展开更多
基于密度泛函理论的第一性原理计算,本文对单层1T-CoI_(2)的原子、电子结构和磁性进行了理论研究.使用广义布洛赫条件结合自旋螺旋方法计算了单层1T-CoI_(2)自旋螺旋的能量色散关系E(q),计算结果表明单层1T-CoI_(2)的基态呈现螺旋反铁磁...基于密度泛函理论的第一性原理计算,本文对单层1T-CoI_(2)的原子、电子结构和磁性进行了理论研究.使用广义布洛赫条件结合自旋螺旋方法计算了单层1T-CoI_(2)自旋螺旋的能量色散关系E(q),计算结果表明单层1T-CoI_(2)的基态呈现螺旋反铁磁,体系中含有键相关的各向异性作用,即Kitaev作用.计算了含有自旋-轨道耦合作用(spin orbital coupling,SOC)和不含有SOC的色散关系,分别将色散关系映射到HeisenbergKitaev模型,成功分解了多近邻海森伯作用参数J、Kitaev作用的K和非对角项Γ.单层1T-CoI_(2)以Heisenberg作用为主导,同时存在着较强的Kitaev相互作用,其中Γ_(1)达到了1.09 meV.可预测Kitaev作用在具有1T结构过渡金属三角格子中具有普遍适用性,表明单层1T-CoI_(2)是Kitaev的备选材料,并且为探索其他二维磁性材料的Kitaev作用奠定了理论基础.展开更多
For the off-diagonal infinite dimensional Hamiltonian operators, which have at most countable eigenvalues, a necessary and sufficient condition of the eigenfunction systems to be complete in the sense of Cauchy princi...For the off-diagonal infinite dimensional Hamiltonian operators, which have at most countable eigenvalues, a necessary and sufficient condition of the eigenfunction systems to be complete in the sense of Cauchy principal value is presented by using the spectral symmetry and new orthogonal relationship of the operators. Moreover, the above result is extended to a more general case. At last, the completeness of eigenfunction systems for the operators arising from the isotropic plane magnetoelectroelastic solids is described to illustrate the effectiveness of the criterion. The whole results offer theoretical guarantee for separation of variables in Hamiltonian system for some mechanics equations.展开更多
In this paper an analytical solution for the stability of the fully developed flow drive in a magneto-hydro-dynamic pump with pulsating transverse Eletro-magnetic fields is presented. To do this, a theoretical model o...In this paper an analytical solution for the stability of the fully developed flow drive in a magneto-hydro-dynamic pump with pulsating transverse Eletro-magnetic fields is presented. To do this, a theoretical model of the flow is developed and the analytical results are obtained for both the cylindrical and Cartesian configurations that are proper to use in the propulsion of marine vessels. The governing parabolic momentum PDEs are transformed into an ordinary differential equation using approximate velocity distribution. The numerical results are obtained and asymptotic analyses are built to discover the mathematical behavior of the solutions. The maximum velocity in a magneto-hydro-dynamic pump versus time for various values of the Stuart number, electro-magnetic interaction number, Reynolds number, aspect ratio, as well as the magnetic and electrical angular frequency and the shift of the phase angle is presented. Results show that for a high Stuart number there is a frequency limit for stability of the fluid flow in a certain direction of the flow. This stability frequency is dependent on the geometric parameters of a channel.展开更多
Water-based rare-earth ferrite (Re xFe 3- xO 4)magnetic fluids were prepared by chemical co-precipitation method. The result shows that saturation magnetic intensity of ferrite magnetic fluids can be improved by addin...Water-based rare-earth ferrite (Re xFe 3- xO 4)magnetic fluids were prepared by chemical co-precipitation method. The result shows that saturation magnetic intensity of ferrite magnetic fluids can be improved by adding Dy 3+ and the saturation magnetic intensity will reach the highest if n(Fe)∶n(Dy 3+ )=30∶1. The modification and formation mechanism of Re xFe 3- xO 4 particles is discussed in detail. The physicochemical properties are investigated by the Gouy magnetic balance, IR, TEM, XRD, and EDX, etc.展开更多
In a Kerr nonlinear blackbody, bare photons with opposite wave vectors and helieities are bound into pairs and unpaired photons are transformed into a different kind of quasiparticle, the nonpolariton. The present pap...In a Kerr nonlinear blackbody, bare photons with opposite wave vectors and helieities are bound into pairs and unpaired photons are transformed into a different kind of quasiparticle, the nonpolariton. The present paper investigates the influence of a single frequency electromagnetic wave on the energy spectrum of the nonpolariton system. We find that the wave can lead to an energy shift of nonpolaritons. Moreover, we calculate the first-order energy shift on certain conditions.展开更多
The purpose of ship deperming is to reduce its permanent magnetism to avoid the threat of magnetic sea-mines which appeared first in battlefields in World War II and stored by many navies and unanimous groups since th...The purpose of ship deperming is to reduce its permanent magnetism to avoid the threat of magnetic sea-mines which appeared first in battlefields in World War II and stored by many navies and unanimous groups since then. Magnetic fields for deperming are mostly generated by electric current through conductor cable and the intensity of such fields decreases with the distance from the cable. In order to impose sufficient field to the ship, the deperming cable is tightly wrapped around the hull of the ship. A cable with superconducting material as the conductor is expected to pass high electric current because of its zero-electric resistivity and has potential to make deperming coil system more separated from the ship hull. In the previous study, we designed superconducting coil system set flat on the seabed for ship deperming by calculating magnetic field generated by the coil based on the characteristic of HTS （high temperature superconducting） tape seen in published papers. This time we have kept our design to utilize HTS tape conductors that are existing and readily available in the open market. In addition, the limitations of the manufacturing potential and capacity of the HTS tape conductor industry have been taken into account for the design. Then we designed the refrigerating system which is to keep the superconducting property of the cable materials.展开更多
Vibration isolation is an effective method to mitigate unwanted disturbances arising from dynamic loading conditions. With smart materials as suitable substitutes, the conventional passive isolators have attained attr...Vibration isolation is an effective method to mitigate unwanted disturbances arising from dynamic loading conditions. With smart materials as suitable substitutes, the conventional passive isolators have attained attributes of semi-active as well as the active control system. In the present study, the non-homogenous field-dependent isolation capabilities of the magnetorheological elastomer are explored under torsional vibrations. Torsional natural frequency was measured using the serial arrangement of accelerometers. Novel methods are introduced to evaluate the torsional stiffness variations of the isolator for a semi-definite and a motor-coupled rotor system. For the semi-definite system, the isolation effect was studied using the frequency response functions from the modal analysis. The speed-dependent variations for motor-coupled rotor system were assessed using the shift in frequency amplitudes from torque transducers. Finite element method magnetics was used to study the variations in the non-homogenous magnetic field across the elastomer. The response functions for the semi-definite rotor system reveal a shift in the frequency in the effect of the magnetic field. Speed-dependent variations in the frequency domain indicate an increment of 9% in the resonant frequency of the system.展开更多
文摘The interaction of magnetic colloidal particles includes the interaction of colloidal particles and the interaction of the moment of magnetism.The interaction of the moment of magnetism is regard as perturbation.According to the low density system of magnetic colloidal particles in water,a theoretic model is set up based on perturbation theory.The relations between internal energy,specific heat of magnetic colloidal particles system and temperature,density of colloidal particles are calculated.The calculated results are useful in explaining the magnetic memory effect.
文摘基于密度泛函理论的第一性原理计算,本文对单层1T-CoI_(2)的原子、电子结构和磁性进行了理论研究.使用广义布洛赫条件结合自旋螺旋方法计算了单层1T-CoI_(2)自旋螺旋的能量色散关系E(q),计算结果表明单层1T-CoI_(2)的基态呈现螺旋反铁磁,体系中含有键相关的各向异性作用,即Kitaev作用.计算了含有自旋-轨道耦合作用(spin orbital coupling,SOC)和不含有SOC的色散关系,分别将色散关系映射到HeisenbergKitaev模型,成功分解了多近邻海森伯作用参数J、Kitaev作用的K和非对角项Γ.单层1T-CoI_(2)以Heisenberg作用为主导,同时存在着较强的Kitaev相互作用,其中Γ_(1)达到了1.09 meV.可预测Kitaev作用在具有1T结构过渡金属三角格子中具有普遍适用性,表明单层1T-CoI_(2)是Kitaev的备选材料,并且为探索其他二维磁性材料的Kitaev作用奠定了理论基础.
基金Supported by the National Natural Science Foundation of China under Grant No. 10962004the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No. 20070126002+1 种基金the Natural Science Foundation of Inner Mongolia under Grant No. 20080404MS0104the Research Foundation for Talented Scholars of Inner Mongolia University under Grant No. 207066
文摘For the off-diagonal infinite dimensional Hamiltonian operators, which have at most countable eigenvalues, a necessary and sufficient condition of the eigenfunction systems to be complete in the sense of Cauchy principal value is presented by using the spectral symmetry and new orthogonal relationship of the operators. Moreover, the above result is extended to a more general case. At last, the completeness of eigenfunction systems for the operators arising from the isotropic plane magnetoelectroelastic solids is described to illustrate the effectiveness of the criterion. The whole results offer theoretical guarantee for separation of variables in Hamiltonian system for some mechanics equations.
文摘In this paper an analytical solution for the stability of the fully developed flow drive in a magneto-hydro-dynamic pump with pulsating transverse Eletro-magnetic fields is presented. To do this, a theoretical model of the flow is developed and the analytical results are obtained for both the cylindrical and Cartesian configurations that are proper to use in the propulsion of marine vessels. The governing parabolic momentum PDEs are transformed into an ordinary differential equation using approximate velocity distribution. The numerical results are obtained and asymptotic analyses are built to discover the mathematical behavior of the solutions. The maximum velocity in a magneto-hydro-dynamic pump versus time for various values of the Stuart number, electro-magnetic interaction number, Reynolds number, aspect ratio, as well as the magnetic and electrical angular frequency and the shift of the phase angle is presented. Results show that for a high Stuart number there is a frequency limit for stability of the fluid flow in a certain direction of the flow. This stability frequency is dependent on the geometric parameters of a channel.
文摘Water-based rare-earth ferrite (Re xFe 3- xO 4)magnetic fluids were prepared by chemical co-precipitation method. The result shows that saturation magnetic intensity of ferrite magnetic fluids can be improved by adding Dy 3+ and the saturation magnetic intensity will reach the highest if n(Fe)∶n(Dy 3+ )=30∶1. The modification and formation mechanism of Re xFe 3- xO 4 particles is discussed in detail. The physicochemical properties are investigated by the Gouy magnetic balance, IR, TEM, XRD, and EDX, etc.
基金Supported by National Natural Science Foundation of China under Grant Nos.10174024 and 10474025
文摘In a Kerr nonlinear blackbody, bare photons with opposite wave vectors and helieities are bound into pairs and unpaired photons are transformed into a different kind of quasiparticle, the nonpolariton. The present paper investigates the influence of a single frequency electromagnetic wave on the energy spectrum of the nonpolariton system. We find that the wave can lead to an energy shift of nonpolaritons. Moreover, we calculate the first-order energy shift on certain conditions.
文摘The purpose of ship deperming is to reduce its permanent magnetism to avoid the threat of magnetic sea-mines which appeared first in battlefields in World War II and stored by many navies and unanimous groups since then. Magnetic fields for deperming are mostly generated by electric current through conductor cable and the intensity of such fields decreases with the distance from the cable. In order to impose sufficient field to the ship, the deperming cable is tightly wrapped around the hull of the ship. A cable with superconducting material as the conductor is expected to pass high electric current because of its zero-electric resistivity and has potential to make deperming coil system more separated from the ship hull. In the previous study, we designed superconducting coil system set flat on the seabed for ship deperming by calculating magnetic field generated by the coil based on the characteristic of HTS （high temperature superconducting） tape seen in published papers. This time we have kept our design to utilize HTS tape conductors that are existing and readily available in the open market. In addition, the limitations of the manufacturing potential and capacity of the HTS tape conductor industry have been taken into account for the design. Then we designed the refrigerating system which is to keep the superconducting property of the cable materials.
基金the support from SOLVE: The Virtual Lab @ NITK (Grant number: No.F.16-35/2009-DL, Ministry of Human Resources Development)
文摘Vibration isolation is an effective method to mitigate unwanted disturbances arising from dynamic loading conditions. With smart materials as suitable substitutes, the conventional passive isolators have attained attributes of semi-active as well as the active control system. In the present study, the non-homogenous field-dependent isolation capabilities of the magnetorheological elastomer are explored under torsional vibrations. Torsional natural frequency was measured using the serial arrangement of accelerometers. Novel methods are introduced to evaluate the torsional stiffness variations of the isolator for a semi-definite and a motor-coupled rotor system. For the semi-definite system, the isolation effect was studied using the frequency response functions from the modal analysis. The speed-dependent variations for motor-coupled rotor system were assessed using the shift in frequency amplitudes from torque transducers. Finite element method magnetics was used to study the variations in the non-homogenous magnetic field across the elastomer. The response functions for the semi-definite rotor system reveal a shift in the frequency in the effect of the magnetic field. Speed-dependent variations in the frequency domain indicate an increment of 9% in the resonant frequency of the system.
