International Journal of Applied Electromagnetics and Mechanics - Volume 47, issue 3

Authors: Cao, Quanliang | Han, Xiaotao | Li, Liang

Article Type: Research Article

Abstract: A simple active microfluidic mixing system based on magnetic actuation strategy of fluids in the microchannel under a hybrid gradient magnetic field was proposed. The hybrid magnetic field, combined of a static gradient magnetic field and an external AC uniform magnetic field, is specially designed to generate periodic magnetic body forces acting on the mixed fluids. Two-dimensional numerical simulation has been performed to investigate the mixing behavior caused by the interactions of magnetic field, fluid flow …and convection-diffusion. Numerical results show that the proposed mixer system achieved up to 97% mixing of the two fluids with a small current flowing in micromagnets. Show more

Keywords: Microfluidic mixing, gradient magnetic field, magnetic force, finite element analysis

DOI: 10.3233/JAE-140057

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 583-592, 2015

Authors: Su, Jen-Pao | Wu, Jong-Shinn | Lee, Ya-Wei

Article Type: Research Article

Abstract: In this study, an electromagnetically controlled cooling device (ECCD) is proposed, employing magnetic nanofluid (MNF) and electromagnetohydrodynamics to ameliorate the waste-heat dissipation of mechatronic systems. The MNF was charged in a condenser chamber as an auxiliary coolant, and was prepared from fine ferromagnetic particles of iron ferrite by using a chemical coprecipitation technique. A radial basis function neural network-based training model was employed for examining the electromagnetic resonance of the ECCD at …a wide heating range. Satisfactory agreement between the experimental and predicted results indicated the accuracy of the model in capturing the ECCD dynamics. The nonlinearity of ECCD dynamics were also identified as a feature of frequency resonance by mapping a discrete-time model into generalized frequency response functions (GFRFs). Accordingly, the effect of electromagnetic induction relating to ECCD performance can be further confirmed. Show more

Keywords: Electromagnetically controlled, magnetic nanofluid (MNF), radial basis function neural network (RBF NN), generalized frequency response functions (GFRFs)

DOI: 10.3233/JAE-140062

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 593-605, 2015

Authors: Hoole, S. Ratnajeevan H. | Karthik, Victor U. | Sivasuthan, Sivamayam | Rahunanthan, Arunasalam | Thyagarajan, Ravi S. | Jayakumar, Paramsothy

Article Type: Research Article

Abstract: This paper reviews mathematical optimization in synthesis and nondestructive evaluation (NDE) by the finite element method in magnetics because background work has been inadequately attributed in the literature. The review identifies the earliest papers and reports new work in nondestructive evaluation and GPU-based matrix solution to save time and memory. Although the genetic algorithm has been applied in optimization, in coupled systems the number of object function evaluations doubles. We therefore examine the use of …graphics processing units (GPUs) to handle the immense computational load. GPU memory limits are often not recognized and are critically limiting when parallelizing the several solutions required in optimization. To overcome this limit, element-by-element finite element matrix processing is employed, making coupled problems practicable on GPUs. We overcome the memory limits element-by-element processing, however, and achieve a GPU speedup of 147 by Jacobi conjugate gradients while forming the matrix of coefficients and of 80 (and growing indefinitely) by Gauss iterations without forming the matrix for situations where memory is scarce such as genetic algorithm optimization where several copies of the matrix have to be held on threads. Show more

Keywords: Review, optimization, finite elements, GPU, NDE, ground vehicles

DOI: 10.3233/JAE-140061

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 607-627, 2015

Authors: Zhou, Yunfei | Liu, Guangdou | Zhou, Rougang | Huo, Ligang | Ming, Wuyi

Article Type: Research Article

Abstract: In this paper the Halbach array with different segments per pole are modeled and compared. The unified harmonic model for the magnetic flux density distribution of the Halbach array with different segments per pole is derived by using Fourier series and magnetic scalar potential. The coil power dissipation and higher harmonics are compared with the Halbach arrays, respectively. The dimension parameter of magnet array is optimized on the basis of minimum coil power dissipation by taking …the magnetically levitated planar motor with moving magnets for example. The genetic algorithm is used to minimize the higher harmonics in z-component of the magnetic flux density distribution. Then the dimension parameters of magnet arrays are obtained, according to that the arrays are compared on the ratio between the higher harmonics and analytical model of z-component of the magnetic flux density distribution and the peak value of z- and x-component of the magnetic flux density distribution. The Halbach array with 3 segments per pole is chosen on the basis of the above comparison. Show more

Keywords: Halbach array, harmonic model, genetic algorithm, power dissipation, planar motor

DOI: 10.3233/JAE-130113

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 629-641, 2015

Authors: Reddy, C.S. | Sharma, A. | Mittal, K.C.

Article Type: Research Article

Abstract: The recovery in a spark gap for repetitive switching has been a long research interest. The surface temperature variation of the anode during switching plays decisive role in recovery of spark gap. This paper presents a method to estimate the effect of anode temperature rise and decay on repetition rate of spark gap. By using this method, the behavior of copper and stainless steel materials were studied for a current pulse of 30 kA. During the pulse …period of 10 μs, the temperature rise for SS is higher than Copper. After current zero, the anode temperature decays to the vaporization temperature of the material and determines the recovery time of the spark gap. This temperature decay is also verified by a heat transient computational model developed in FEM based software. Simulations has been carried out for different materials including Cu and SS. Some simulations are in good agreement with existing experimental data. The decay time for current pulses 5 kA, 10 kA, 15 kA, 20 kA, 25 kA and 30 kA are estimated. The simulation shows higher decay rate for tungsten and lower decay rate for graphite. Similar trend has been observed for silver and copper. Theoretical analysis of recovery times, heat transfer simulation model for different anode materials are presented and the results are discussed. Show more

Keywords: Anode temperature recovery, anode materials, spark gap recovery, specific heat flux, vaporization

DOI: 10.3233/JAE-140049

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 643-651, 2015

Authors: Tsai, Yi-Hsien | Hsue, Ching-Wen | Chen, I-Fong

Article Type: Research Article

Abstract: In this paper, a discrete-time domain synthesizing method was presented to design and implement the active integrator in the microwave frequency range. The frequency-domain GaAs Filed Effect Transistor (FET) scattering parameters are converted into the Z-domain representations. The transfer functions of the networks are formulated in the Z domain and implemented by using cascade serial line and GaAS FET. There are good agreement between the experimental results and the theoretical values.

Keywords: Active integrator, microwave, Z transforms

DOI: 10.3233/JAE-140042

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 653-660, 2015

Authors: Dash, S.K. | Swarup, K.S. | Rajan, K.K.

Article Type: Research Article

Abstract: Magnetic Bearing, especially Active Magnetic Bearing (AMB) is arguably most preferred bearing for the process dealing with highly reactive environment, high speed operation and where the process required least contamination. They are also being tried for Fly wheels and Wind generators. They continue to be evolved since last several decades. Quite a few processes like application of AMB in high temperature Liquid Sodium high temperature applications call for development of large-working-gap active magnetic bearings …(AMB). Smooth operation of AMB depends on hypersensitive position stiffness and Current stiffness, which fluctuates due to differential-thermal-expansion induced air gap variation. So, large gap, necessitates flatter open loop position stiffness than that of contemporary magnetic actuators. In this work, a goal seeking optimization methodology is employed for double acting AMB system where a combination of higher (CRGO electrical steel) and lower saturating magnetic material (Mu metal) is used. A less variant position stiffness across the air gap was arrived at after getting optimized design variables constituting geometry and excitation current parameters. This investigation opens up a new way to attain position stiffness in AMB system which is less sensitive to positional variation of rotor in air gap. This paper proposes an innovative and first-of-its-kind bi-material core material with goal driven optimized magnetic actuator design which can afford to have air gap variation during operation. Show more

Keywords: Thrust magnetic bearing, position stiffness, goal driven optimization, evolution strategy, bi-materialactuator

DOI: 10.3233/JAE-140041

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 661-680, 2015

Authors: Yang, Wan'an | Zhao, Xin | Hu, Chao | Qin, Fengqing

Article Type: Research Article

Abstract: In order to actively maneuver the robotic capsule and make it small to swallow easily, we propose that the capsule incorporating the circuits, batteries, imaging device, etc. is looped by a magnet ring with 1 mm thickness. Another cuboidal or cylindrical permanent magnet attracts or pushes or rotates the robotic capsule to make closer scrutiny for the interesting area. Before designing the control system, the force regarding distance between cuboidal or cylindrical magnet and magnet ring …should be known in advance. The mathematic model of magnetic force that the cuboidal or cylindrical permanent magnet exerts on the magnet ring is given for that purpose. The experiments state that the force the robotic capsule requires can be produced by cuboidal or cylindrical magnet when it's moving forward in the pig's small bowel. The experiments also show the relationships between the force and the shape of cuboidal magnet or cylindrical magnet, which can help to choose the magnets with optimal dimensions. Show more

Keywords: Maneuver, robotic capsule, permanent-magnet ring, force model, optimal dimension

DOI: 10.3233/JAE-140034

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 677-689, 2015

Authors: Peng, Cong | Fang, Jiancheng | Wang, Chun'e

Article Type: Research Article

Abstract: This paper focuses on the steering law for a magnetically suspended momentum wheel (MSMW) cluster with vernier gimballing capability. Firstly, the dynamical model of the spacecraft equipped with the MSMW cluster is constructed in a generalized form. Then a new steering law for the MSMW cluster is proposed to switch between two operation modes: the conventional momentum wheel mode for outputting spin torque, and the double gimbaled wheel mode for outputting the gyroscopic torques. Compared with …the traditional steering law, the proposed steering law with two modes switch can avoid the small vernier gimbal angles saturation. Finally, simulation results demonstrate the merits of using vernier gimballing capability and the effectiveness of the proposed steering law in providing the command torques and avoiding the saturation of the vernier gimbal angles. Show more

Keywords: Magnetic bearing, magnetically suspended momentum wheel, MSMW application, vernier gimballing, steering law

DOI: 10.3233/JAE-140024

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 691-704, 2015

Authors: Liu, Shuang | Li, Xue | Zhao, Shuangshuang | Li, Haibin

Article Type: Research Article

Abstract: Considering the torsional vibration in transmission system driven by AC asynchronous motor, this paper proposes a dynamical model of nonlinear electromechanical coupling system by using the energy method. The effect of electromagnetic factors on nonlinear dynamic performance of the electromechanical coupling system is investigated. Firstly, the static bifurcation characteristic under the non-autonomous condition is studied based on the singularity theory of nonlinear system. Secondly, the Hopf bifurcation point and the direction of …bifurcation are determined based on the Hopf bifurcation theory. Finally, the bifurcation diagram, Poincare map and the largest Lyapunov exponent are given, which show the influence of electromagnetic stiffness and electromagnetic damping on the chaotic motions of the system. Show more

Keywords: Electromechanical coupling, the energy method, bifurcation, chaos

DOI: 10.3233/JAE-140059

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 3, pp. 705-717, 2015