The analytical design and evaluation of electromagnets

Stress Analysis and Bobbin Structure Optimization Design of a 35kV HTS-controllable Reactor

This paper describes a comparative study of finite-difference time-domain (FDTD) and analytical evaluations of electromagnetic fields in the vicinity of dimers of metallic nanospheres of plasmonics-active metals. The results of these two computational methods, to determine electromagnetic field enhancement in the region often referred to as "hot spots" between the two nanospheres forming the dimer, were compared and a strong correlation observed for gold dimers. The analytical evaluation involved the use of the spherical-harmonic addition theorem to relate the multipole expansion coefficients between the two nanospheres. In these evaluations, the spacing between two nanospheres forming the dimer was varied to obtain the effect of nanoparticle spacing on the electromagnetic fields in the regions between the nanostructures. Gold and silver were the metals investigated in our work as they exhibit substantial plasmon resonance properties in the ultraviolet, visible, and near-infrared spectral regimes. The results indicate excellent correlation between the two computational methods, especially for gold nanosphere dimers with only a 5-10% difference between the two methods. The effect of varying the diameters of the nanospheres forming the dimer, on the electromagnetic field enhancement, was also studied.

Evaluation method for spatial straightness errors based on minimum zone condition

Effect of the soil slope on the cost-efficient optimum discrete design of reinforced concrete isolated footings

The optimum design of a thermoelectric system for application in car seat climate control has been modeled and its performance evaluated experimentally. The optimum design of the thermoelectric device combining two heat exchangers was obtained by using a newly developed optimization method based on the dimensional technique. Based on the analytical optimum design results, commercial thermoelectric cooler and heat sinks were selected to design and construct the climate control heat pump. This work focuses on testing the system performance in both cooling and heating modes to ensure accurate analytical modeling. Although the analytical performance was calculated using the simple ideal thermoelectric equations with effective thermoelectric material properties, it showed very good agreement with experiment for most operating conditions.

In this study, we performed a novel synthesis of one-dimensional (1-D) SmCo/FeCo core-shell nanomagnets with noticeably enhanced exchange-coupling interactions via electrospinning and a subsequent heat treatment process coupled with an electroless plating process. We discuss the influence of the 1-D shape in enhancing the magnetic properties, particularly exchange-coupling interactions of the rare-earth magnet, compared to the zero-dimensional (0-D) core-shell magnet. With the advent of high-efficiency miniaturized devices in modern industry, there is high demand for enhanced permanent magnets. Their applications are wide-ranging and include motors in automobiles, data storage devices, electromechanical devices, and electronics. Theoretically, one way to improve the inherent magnetic properties of rare-earth nanomagnets (i.e., SmCo) is to fabricate a soft magnet (i.e., FeCo)-coated core-shell nanomagnet that participates in exchange-coupling interaction with the interphase. However, many previous reports showed only marginal enhancement in magnetic properties, ascribed to the inevitable tendency of 0-D nanoparticles to agglomerate, resulting in non-ideal magnetic coupling. Moreover, there have been no reports on SmCo-based core-shell nanoscale magnets with a 1-D structure, and the effect of magnet shape on the magnetic properties (particularly on exchange-coupling effect) is not well understood. In this regard, such a comparison is a meaningful approach in the design of permanent magnets for achieving effective magnetic coupling. We clarified the distinct effect of magnet shape based on the analytical results. Interestingly, despite the tailored thickness of the FeCo layer on the Sm2Co17, there was no increase in magnetization or (BH)max enhancement in 0-D magnets, resulting from agglomeration, while 1-D magnets showed an all-time high effective exchange-coupling interaction. Substantial enhancement in magnetization and a (BH)max value of about 10.14 MG·Oe were obtained in the 1-D nanostructure, representing straightforward enhancement of greater than 145% compared to 0-D magnetic nanostructures. Our work also elucidates the magnetic behavior within the hard-soft magnetic phases of the 1-D SmCo/FeCo nanocomposite, including a comparison with the 0-D bi-magnet. We expect that this understanding can be extended to synthesis of a super-strong exchange-coupled magnet, overcoming the limitations of traditional magnetic materials. Moreover, the present work would be of particular interest to researchers working on a broad range of syntheses and advanced magnetic devices. Figure 1

This paper addresses the problem of low electromagnetic weft insertion acceleration performance of extra-large width automatic looms. Based on single-stage electromagnetic weft insertion and multi-stage intermittent electromagnetic weft insertion, a sectional combined continuous acceleration electromagnetic weft insertion design plan is proposed. First, a new type of weft gripper for electromagnetic weft insertion is designed on the basis of the traditional projectile, and a segmented combined structure optimization design is carried out on the 90 mm single-stage coil. Next, the electromagnetic weft insertion movement model is established to analyze the force and movement speed of the gripper during the movement. The amount of work done by the electromagnetic force of the combined coil determines the exit speed of the weft gripper. Finally, in order to find the best parameters of the combined coil structure to meet the requirements of the launch speed, the steady state and transient performance of the segmented combined continuous acceleration coil are analyzed using Maxwell simulation software. The launch performance of the combined coil with different axial lengths of 45 mm, 30 mm, and 15 mm is compared. The results show that the entire acceleration process is more stable and efficient when the combined coil length is 30 mm, the inner diameter is 18 mm, and the number of turns is 600.

Dielectric lenses are widely used in terahertz imaging and communication systems to focus or collimate the Gaussian beam by adjusting the phase distribution of wave front. However, due to the high frequency and short wavelength of the terahertz band, the focusing lenses used in the application systems are usually electrically large, which bring the extremely difficulty to carry out efficient electromagnetic (EM) simulation and optimization design. In this paper, a dimensionality reduction concept was introduced to achieve efficient design and optimization of electrically-large terahertz lenses, which have symmetric structures and are commonly used in quasi-optical systems, such as circular lenses and cylindrical lenses. To precisely solve the EM problem with reduced dimension, a two-dimensional moment method (2D-MOM) for homogeneous dielectric targets was studied and successfully developed by solving the surface coupled integral equation discretized with appropriate basis and test functions. Then, the dimensionality reduction approach with the combination of the ray-tracing method (RTM) and the 2D-MOM was developed for the shaped design of terahertz lens with high efficiency. A 0.3THz lens with diameter 10cm was designed with the proposed approach as an example, with its pattern measured by a terahertz field scanning platform. It's found that, with the dimensional reduction, the unknowns can be reduced more than 1500 times and the memory required can be reduced more than 2.5 million times, as compared to the traditional 3D-MOM simulation. And the simulation results agree well with the experiments, which both demonstrate the greatly improved performance of the lens designed by the proposed approach, as compared to the standard lens.

Artificial bee colony algorithm (ABC) developed by inspiring the foraging phenomena of the natural honey bees is a simple and powerful metaheuristic optimization algorithm. The performance of single objective ABC performance has been well demonstrated by implemented to different design optimization problems from elec-trical and mechanical to civil engineering. Its efficacy is anticipated in the multi-objective design optimization of multilayer microwave dielectric filters (MMDFs) which is a challenging multi-objective problem falls into the context of electromagnetic (EM) design in electrical engineering. The MMDF is composed of superimposed multiple dielectric layers in order to pass or stop the EM wave at the desired frequency bands. An accurate dual-objective EM model of MMDF is constituted to be the total reflection coefficients for oblique incident wave angular range with transverse electric (TE) or transverse magnetic (TM) polarizations. The objective functions depend on the total reflection (TR) at the pass and stop band re-gions. Three types of the MDFs that are low pass (LP), high pass (HP) and band pass (BP) MMDFs are optimally designed across the constituted dual-objective EM model with a frequency dependent material database through using the multi-objective ABC (MO-ABC) strategy. The Pareto optimal solutions are refined within the possible solutions for synchronously minimizing the objective func-tions. The global optimal MMDF designs are selected from the Pare-to optimal solutions by providing the trade-off therein between the objective functions. The performance study regarding the frequen-cy characteristics of the designed MMDFs are well presented via numerical and graphical results. It is hence demonstrated that MO-ABC is even versatile and robust in the multi-objective design of MMDFs.

Airflow characteristics in ventilated and air-conditioned spaces play an important role to attain comfort and hygiene conditions. This paper utilizes a 3D time-dependent Computational Fluid Dynamics (CFD) model to assess the airflow characteristics in different air-conditioned spaces. It is found that the optimum airside design system can be attained, if the airflow is directed to pass all the enclosure areas before the extraction. Still most of these factors and evaluation indices have the shortage of adequately describe the influence of the recirculation zones on the occupancy zone and also on the fresh supplied air. The model of evaluation should assess the airflow characteristics in any enclosure according to its position in the enclosure and the expected target of it along its pass to the extraction.

Optimization algorithms play a critical role in electromagnetic device designs due to the ever-increasing technological and economical competition. Although evolutionary algorithm-based methods have successfully been applied to different design problems, these methods exhibit deficiencies when solving complex problems with multimodal and discontinuous objective functions, which is quite common in electromagnetic device optimization designs. In this paper, a hybrid multi-objective optimization algorithm based on a non-dominated sorting genetic algorithm (NSGA-II) and a multi-objective particle swarm optimization method (MOPSO) is proposed. In order to enhance the convergence and diversity performance of the algorithm, a new population update mechanism of MOPSO is introduced. Moreover, an adaptive operator involving crossover and mutation is presented to achieve a better balance between global and local searches. The performance of the hybrid algorithm is validated using standard test functions and the multi-objective design of a superconducting magnetic energy storage (SMES) device. Numerical results demonstrate the effectiveness and superiority of the proposed method.

This paper is focused on the electromagnetic and structural design of high-speed synchronous reluctance (HS-SyR) machines. Both design aspects are equally taken into account due to high speed requirements. Two design procedures, both based on multi-objectives stochastic optimization algorithms (OA) and Finite Element Analysis (FEA), are presented and compared in terms of computational time and quality of the final result. The first design procedure combines an electromagnetic FEA with an analytical rotor structural design. The second procedure evaluates both electromagnetic and structural performance using FEA simulations within the optimization. The former approach needs a structural refinement stage of the rotor geometry. The latter gives rotor designs ready for manufacturing at the cost of increased computational resources. The two approaches have been investigated considering the rotor design of an 80.000 rpm SyR motor for aeronautical applications. Finally, a sensitivity analysis has been performed to identify which variables most affect structural performance and which parameters need tighter manufacturing tolerances.

This paper explores the design, analysis and simulation of a high speed disk-type (axial flux) permanent magnet (AFPM) synchronous motor. This motor has rated power 0.5 hp at speed of 60,000 rpm used in some special industrial applications. The design of high speed AFPM motor is performed using analytical relations, and sizing of various components including dimensions, magnetic specifications and materials are presented in details. To validate the performed analytical design, the designed motor is modeled using finite element analysis (FEA) in Maxwell software. The motor behavior and characteristics are investigated in steady state using magnetostatic analysis as well as transient state by transient analysis of Maxwell software. The results of finite element analysis confirm the analytical design results and there is good agreement between both analytical and FEA methods for torque, efficiency and flux density quantities.

General problems of optimization of iron-core electromagnets are considered. The use of analytical and numerical methods are compared. Various models of electromagnets are examined, taking into account the magnetization curve of iron, operating conditions, the construction of coils, etc. The possibility of tackling the automatic design of iron-core electromagnets with cylindrical symmetry is demonstrated. The optimization procedure can also be used in the design of magnetic devices of complicated structure. >

The frequency characteristics for the power dividers with ferrite toroids, which are extensively used in CATV and/or MATV systems, are analyzed. The analytical optimum design method for the weakly-coupled power divider by the simplified model and the numerical optimum design method for the tightly-coupled power divider by the exact model are proposed, and the designed power dividers with ferrite toroids by the proposed methods have much improved frequency characteristics compared with the original power dividers. Thus, the useful bandwiths of all the power dividers have been extended from 5 to 500 MHz. Practical measurements show very good agreements with theoretical results, and, hence, the validity of the analyses and design methods for the power dividers with ferrite toroids are confirmed. Furthermore, the relations between the optimum circuit and ferrite constants have been clarified in reference to L0(i)Kfm.