WIRELESS power transmission, RAPID prototyping, RADIO frequency, GOLD coatings, and STAINLESS steel
This article presents an electromagnetically powered stent designed for hyperthermia treatment of in-stent restenosis. The stent device based on medical-grade stainless steel serves as a radio frequency (RF) inductive receiver to produce mild heating wirelessly through resonant-coupling power transfer, while acting as a mechanical scaffold inside an artery similar to commercial stents. The device and its custom transmitter are prototyped and optimized to show efficient wireless power transfer and stent heating through in vitro tests. The inductive stent with its helical pattern is gold coated to achieve a $3.5\times $ higher quality ($Q$) factor, improving heating performance of the device. The combinational use of independent resonant antennas with the power antenna is found to significantly boost stent temperature by up to 96% with an intermediate tissue layer. Upon matching the frequencies at which the $Q$ factors of the inductive stent, power antenna, and booster antenna are peaked, the stent excited through 10 mm-thick tissue exhibits a temperature increase of 18 °C, well over a necessary level for targeted hyperthermia treatment. The prototype achieves heating efficiencies (HEs) of 15.5–3.2 °C/W with a tissue thickness of 5–15 mm. These results indicate that the proposed resonant-heating stent system with the prototyped transmitter is promising for further development toward its clinical application. [ABSTRACT FROM AUTHOR]
IEEE Transactions on Power Electronics. Sep2019, Vol. 34 Issue 9, p8715-8723. 9p.
RAPID prototyping, CURRENT-voltage characteristics, and FEEDBACK (Psychology)
Using a photovoltaic (PV) emulator (PVE) simplifies the testing of the PV generation system. However, conventional controllers used for PVEs suffer from oscillating output voltage, requiring a high number of iterations, or being too complex to be implemented. This paper proposes a controller based on a resistance feedback control strategy that produces a stable and fast converging operating point for the PVE. The resistance feedback control strategy requires a new type of PV model, which is the current–resistance (I–R) PV model. This model is computed using a binary search method at a fast convergence rate. It is combined with a closed-loop buck converter using a proportional-integral controller to form the resistance feedback control strategy. The PVE's controller is implemented into dSPACE ds1104 hardware platform for experimental validation. The acquired experimental results show that the proposed PVE is able to follow the current–voltage characteristic of the PV module accurately. In addition, the PVE's efficiency is more than 90% under maximum power point operation. The transient response of the proposed PVE is similar to the PV panel during irradiance changes. [ABSTRACT FROM AUTHOR]
This paper presents a discrete-time neural inverse optimal control for induction motors, which is implemented on a rapid control prototyping (RCP) system using a C2000 Microcontroller-Simulink platform. Such controller addresses the solution of three issues: system identification, trajectory tracking, and state estimation, which are solved independently. The neural controller is based on a recurrent high order neural network (RHONN), which is trained with an extended Kalman filter. The RHONN is an identifier to obtain an accurate motor model, which is robust to external disturbances and parameter variations. The inverse optimal controller is used to force the system to track a desired trajectory and to reject undesired disturbances. Moreover, the controller is based on a neural model and does not need the a-priori knowledge of motor parameters. A supertwisting observer is implemented to estimate the rotor magnetic fluxes. The hub of the RCP system is a TMS320f28069M MCU, which is an embedded combination of a 32-bit C28x DSP core and a real-time control accelerator. This Microcontroller is fully programmable from the Simulink environment. Simulation and experimental results illustrate the performance of the proposed controller and the RCP system, and a comparison with a control algorithm without the neural identifier is also included. [ABSTRACT FROM AUTHOR]
MAGNETIC resonance imaging, RADIO frequency, HIGH resolution imaging, LASER beam cutting, and HUMAN body
Magnetic resonance imaging (MRI) is one of the most powerful imaging modality in clinics and is essential for the diagnosis of strokes through carotid artery imaging. The limiting factor for high-quality MRI is the signal-to-noise ratio (SNR) performance of the radio frequency (RF) coils. The current RF surface coils, however, are made of rigid or semiflexible materials with very limited bending properties. As a result, their SNR is limited because they cannot be placed very close to the imaging area, thus receiving noises from parts of the human body, which are not intended to be imaged. Taking advantage of the computerized embroidery and laser cutting technology, in this paper, we utilize electrotextile to design, fabricate, and measure multilayer RF coil array system for 3 Tesla (3T) MRI to improve the SNR performance. The proposed RF coil array system provides an ergonomic and high-performance solution to the 3T MRI systems. A roadmap to systematically design electrotextile RF coil arrays is proposed. RF coil array is characterized to have the accurate resonant frequency, good impedance matching, and low mutual coupling. In addition, magnetic field distribution, bending effects, and human body effects are also discussed. A systematic method to characterize the performance of the electrotextile pattern is studied and used to assist the development and performance characterization. Finally, the high resolution and high SNR images of various kinds of phantoms are obtained using the University of California at Los Angeles (UCLA) Antenna Lab electrotextile coil array after its integration with the 3T MRI scanners at UCLA David Geffen School of Medicine Translational Research Imaging Center. Compared with the conventional surface coil, more than 10 dB SNR increase is observed at the depth of 0.5 cm and 3 dB increase at the depth of 3 cm. [ABSTRACT FROM AUTHOR]
Li, Jian, Lu, Yang, Cho, Yun-Hyun, and Qu, Ronghai
IEEE Transactions on Industry Applications. Jul-Aug2019, Vol. 55 Issue 4, p3555-3565. 11p.
MACHINING, MANUFACTURING processes, PERMANENT magnets, MACHINE tools, STATORS, POWER capacitors, and HEAT transfer
This paper presents a design process and a detailed multiphysics analysis of an axial-flux permanent-magnet synchronous machine for large-power direct-drive applications. The machine in this paper is 130 kW at 26 r/min with a dual-stator inner-rotor structure. A stator core that is assembled with segmented and prewound teeth is first proposed and applied in a large-power axial-flux permanent-magnet machines (AFPMs). Through this method, the challenges of manufacturing large-diameter AFPMs can be solved. A novel water-cooling system is embedded in the machine to transfer the heat. In addition, the assembling procedure and the manufacture process are also proposed, and a novel distributed follower bearing is used to reduce the deformation and stress of the rotor disk. Finally, based on the multiphysics design, a prototype machine is manufactured and tested. The experiment results match well with the finite-element analysis. [ABSTRACT FROM AUTHOR]
RAPID prototyping, MICROWAVE circuits, LOW Temperature Cofired Ceramic technology, LASER machining, and ACOUSTIC couplers
An improved technique for laser prototyping of microwave circuits in low-temperature cofired ceramic (LTCC) technology is presented. This builds on the method of laser machining of conductor layers in unfired LTCC tapes. The proposed process presents the hybrid approach of circuit fabrication by employing both unfired and post fired laser machining of LTCC substrate, hence giving more flexibility of realizing multilayer components. This allows the low-tolerance microwave structures like couplers and filters to be fabricated on the outer layers because shrinkage uncertainty is no longer a problem. Track widths and gaps of 30 \mu \textm are demonstrated with an edge definition of ±2 \mu \textm . A stripline coupler and a four-layer spiral inductor is successfully fabricated using this technique to demonstrate the process. The improved process can produce high-precision microwave and millimeter-wave components on the outer layers and provides rapid system-in-package prototyping for research and development. [ABSTRACT FROM AUTHOR]