There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Starting from Tesla's principles of wireless power transfer a century ago, this critical review outlines recent magneto-inductive research activities on wireless power transfer with the transmission distance greater than the transmitter coil dimension. It summarizes the operating principles of a range of wireless power research into 1) the maximum power transfer and 2) the maximum energy efficiency principles. The differences and the implications of these two approaches are explained in terms of their energy efficiency and transmission distance capabilities. The differences between the system energy efficiency and the transmission efficiency are also highlighted. The review covers the two-coil systems, the four-coil systems, the systems with relay resonators and the wireless domino-resonator systems. Related issues including human exposure issues and reduction of winding resistance are also addressed. The review suggests that the use of the maximum energy efficiency principle in the two-coil systems is suitable for short-range rather than mid-range applications, the use of the maximum power transfer principle in the four-coil systems is good for maximizing the transmission distance, but is under a restricted system energy efficiency (<;50%); the use of the maximum energy efficiency principle in relay or domino systems may offer a good compromise for good system energy efficiency and transmission distance on the condition that relay resonators can be placed between the power source and the load.

A Critical Review of Recent Progress in Mid-Range Wireless Power Transfer

Thank you for downloading linear and nonlinear programming. As you may know, people have search numerous times for their favorite novels like this linear and nonlinear programming, but end up in malicious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they juggled with some infectious bugs inside their desktop computer. linear and nonlinear programming is available in our book collection an online access to it is set as public so you can download it instantly. Our digital library spans in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the linear and nonlinear programming is universally compatible with any devices to read.

Linear And Nonlinear Programming

Electric field depth-focality tradeoff in transcranial magnetic stimulation: simulation comparison of 50 coil designs.

Wireless charging is a technology of transmitting power through an air gap to electrical devices for the purpose of energy replenishment. The recent progress in wireless charging techniques and development of commercial products have provided a promising alternative way to address the energy bottleneck of conventionally portable battery-powered devices. However, the incorporation of wireless charging into the existing wireless communication systems also brings along a series of challenging issues with regard to implementation, scheduling, and power management. In this paper, we present a comprehensive overview of wireless charging techniques, the developments in technical standards, and their recent advances in network applications. In particular, with regard to network applications, we review the static charger scheduling strategies, mobile charger dispatch strategies and wireless charger deployment strategies. Additionally, we discuss open issues and challenges in implementing wireless charging technologies. Finally, we envision some practical future network applications of wireless charging.

Wireless Charging Technologies: Fundamentals, Standards, and Network Applications

A dynamic core loss model is proposed to estimate core loss in both soft ferromagnetic and power ferrite materials with arbitrary flux waveforms. The required parameters are the standard core loss coefficients that are either directly provided by manufacturers or extracted from the loss curve associated with sinusoidal excitation. The model is applied to calculating core loss in both two-dimensional and three-dimensional transient finite element analysis, and the results are compared with measured data.

A dynamic core loss model for soft ferromagnetic and power ferrite materials in transient finite element analysis

A non-radiative energy transformer, commonly referred as Witricity and based on `strong coupling' between two coils which are separated physically by medium-range distances, is proposed to realize efficient wireless energy transfer. The distance between the resonators can be larger than the characteristic sizes of each resonator. Non-radiative energy transfer between the first resonator and the second resonator is facilitated through the coupling of their resonant-field evanescent tails. The proposed system operates as traditional inductive magnetic coupling devices when the operating frequencies are not the resonant frequency. Corresponding finite element analysis (FEA) and experiments have been carried out to facilitate quantitative comparison. Compared with typical magnetic inductive coupling energy transmission devices, the efficiency of the proposed system is much higher. This investigation indicates that it is feasible to use wireless energy transfer technology to recharge batteries, particularly in implant devices.

A Comparative Study Between Novel Witricity and Traditional Inductive Magnetic Coupling in Wireless Charging

Wireless power transfer using strongly coupled electromagnetic resonators is a recently explored technology. Although this technology is able to transmit electrical energy over a much longer distance than traditional near field methods, in some applications, its effective distance is still insufficient. In this paper, we investigate a relay effect to extend the energy transfer distance. Theoretical analysis is performed based on a set of coupled-mode equations. Experiments are conducted to confirm the theoretical results and demonstrate the effectiveness of the relay approach. Our results show that the efficiency of power transfer can be improved significantly using one or more relay resonators. This approach significantly improves the performance of the present two-resonator system and allows a curved path in space to be defined for wireless power transfer using smaller resonators.

Relay Effect of Wireless Power Transfer Using Strongly Coupled Magnetic Resonances

In this paper, a novel direct-drive double rotor Vernier panent magnet (DR-VPM) machine is proposed and analyzed. The key of the design is to incorporate two concentric rotors and the Vernier structure within one permanent magnet (PM) machine, while keeping the machine volume and slot number unchanged. The main merits of this proposed machine are its compact structure, improved torque density, reduced stator end winding length, and reduced copper loss. The operating principle of the machine is discussed and its steady and transient performances are analyzed using circuit-field-motion coupled time-stepping finite element method (CFM-TS-FEM). A dual-excitation PM Vernier (DE-VPM) machine and a single outer rotor PM Vernier (SR-VPM) machine are designed and compared with this proposed Vernier PM machine using CFM-TS-FEM. Comparison results as reported are used to confirm and validate the advantageous performance of the proposed machine.

Quantitative Comparison of Novel Vernier Permanent Magnet Machines

Vernier permanent magnet (VPM) machines can be utilized for direct drive applications by virtue of their high torque density and high efficiency. The purpose of this paper is to develop a general design guideline for split-slot low-speed VPM machines, generalize the operation principle, and illustrate the relationship among the numbers of the stator slots, coil poles, permanent magnet (PM) pole pairs, thereby laying a solid foundation for the design of various kinds of VPM machines. Depending on the PM locations, three newly designed VPM machines are reported in this paper and they are referred to as 1) rotor-PM Vernier machine, 2) stator-tooth-PM Vernier machine, and 3) stator-yoke-PM Vernier machine. The back-electromotive force (back-EMF) waveforms, static torque, and air-gap field distribution are predicted using time-stepping finite element method (TS-FEM). The performances of the proposed VPM machines are compared and reported.

Weinong Fu

Papers

A dynamic core loss model for soft ferromagnetic and power ferrite materials in transient finite element analysis

A Comparative Study Between Novel Witricity and Traditional Inductive Magnetic Coupling in Wireless Charging

Relay Effect of Wireless Power Transfer Using Strongly Coupled Magnetic Resonances

Quantitative Comparison of Novel Vernier Permanent Magnet Machines

Design and Comparison of Vernier Permanent Magnet Machines