scholarly journals High efficiency class-D RF amplifiers and mobile NMR systems

2021 ◽  
Author(s):  
◽  
John Z. Zhen
Keyword(s):  
High Frequency ◽  
High Efficiency ◽  
Industrial Applications ◽  
Pulse Generation ◽  
Integrated System ◽  
Mobile System ◽  
Rf Amplifiers ◽  
Fully Integrated ◽  
Class D ◽  
Mobile Nmr

<p>This thesis details the development of a hand held mobile NMR system. The new system addressed the drawbacks on most of the existing NMR systems of being physically large and heavy with poor power inefficiency. In order to achieve the goal of producing a compact and power efficient NMR system, several high efficiency Class D RF amplifiers were developed which showed efficiencies of over 80%. The single cycle controlled PWM amplifier working at 2 MHz was a novel design and no other PWM Class D amplifiers has been reported to operate at high frequency with output power greater than 100 W. Development of the 20 MHz amplifier with 100 W constant amplitude output showed that the Class D amplifiers are suitable for NMR applications even at high frequency and further development of this amplifier to work at 17 MHz with amplitude modulation was successful. It paved the way for the development of a full mobile system with the newly available 17 MHz Mini-MOUSE sensor. The fully integrated mobile system was developed using SoC FPGA technologies. The use of a 400 Msps DDS device for RF pulse generation results in a broadband system. A duplexer was developed to enable sensor tuning and matching with the receiver amplifiers on the duplexer output stage provided 72 dB gain. The web based control program running on an iPad has shown great portability and it allows the system to be operated outdoors, even in remote areas. Experiments on industrial applications has shown successful T2eff measurements on polymer composites and rubber samples and showed the potential for such a system to be used in industrial applications. The fully integrated system prototype fits in a case measuring 140x120x100 mm (LxWxH) and weighs 800 grams and fulfil all the requirements for a mobile NMR system.</p>

scholarly journals High efficiency class-D RF amplifiers and mobile NMR systems

2021 ◽  
Author(s):  
◽  
John Z. Zhen
Keyword(s):  
High Frequency ◽  
High Efficiency ◽  
Industrial Applications ◽  
Pulse Generation ◽  
Integrated System ◽  
Mobile System ◽  
Rf Amplifiers ◽  
Fully Integrated ◽  
Class D ◽  
Mobile Nmr

<p>This thesis details the development of a hand held mobile NMR system. The new system addressed the drawbacks on most of the existing NMR systems of being physically large and heavy with poor power inefficiency. In order to achieve the goal of producing a compact and power efficient NMR system, several high efficiency Class D RF amplifiers were developed which showed efficiencies of over 80%. The single cycle controlled PWM amplifier working at 2 MHz was a novel design and no other PWM Class D amplifiers has been reported to operate at high frequency with output power greater than 100 W. Development of the 20 MHz amplifier with 100 W constant amplitude output showed that the Class D amplifiers are suitable for NMR applications even at high frequency and further development of this amplifier to work at 17 MHz with amplitude modulation was successful. It paved the way for the development of a full mobile system with the newly available 17 MHz Mini-MOUSE sensor. The fully integrated mobile system was developed using SoC FPGA technologies. The use of a 400 Msps DDS device for RF pulse generation results in a broadband system. A duplexer was developed to enable sensor tuning and matching with the receiver amplifiers on the duplexer output stage provided 72 dB gain. The web based control program running on an iPad has shown great portability and it allows the system to be operated outdoors, even in remote areas. Experiments on industrial applications has shown successful T2eff measurements on polymer composites and rubber samples and showed the potential for such a system to be used in industrial applications. The fully integrated system prototype fits in a case measuring 140x120x100 mm (LxWxH) and weighs 800 grams and fulfil all the requirements for a mobile NMR system.</p>

scholarly journals LLC and CLLC Resonant Converters Based DC Transformers (DCXs): Characteristics, Issues, and Solutions

2021 ◽  
Vol 6 (4) ◽  
pp. 332-348
Author(s):  
Yuqi Wei ◽  
Keyword(s):  
Resonant Frequency ◽  
High Frequency ◽  
High Efficiency ◽  
Industrial Applications ◽  
Resonant Converters ◽  
Frequency Tracking ◽  
Main Work ◽  
Small Footprint ◽  
Low Efficiency ◽  
Voltage Conversion

Conventional line frequency transformers have the disadvantages of large volume and low efficiency. The medium or high frequency transformers based on power converters can achieve high power conversion with small footprint have drawn popularity in numerous industrial applications. Unregulated resonant converters, LLC and CLLC resonant converters, with fixed voltage conversion ratio operating at resonant frequency, which are also known as DC transformers (DCXs), are attractive owning to their high efficiency characteristic. Nevertheless, there are issues associated with DCXs in real applications. Regulation capability and automatic resonant frequency tracking capability are the two most important issues for DCXs. The main work of this paper is to characterize the resonant converters based DCXs, and overview the issues and solutions associated with DCXs. Guidelines can be provided for researchers and engineers when designing the resonant converters based DCXs.

scholarly journals The design of auto-tuning capacitive power transfer for rotary applications using phased-locked-loop

2019 ◽  
Vol 10 (1) ◽  
pp. 307
Author(s):  
N. Nabila ◽  
Shakir Saat ◽  
Y. Yusop ◽  
M.S. M Isa ◽  
A.A. Basari
Keyword(s):  
High Frequency ◽  
Power Efficiency ◽  
High Efficiency ◽  
Plate Thickness ◽  
Industrial Applications ◽  
Power Transfer ◽  
Wireless Power ◽  
Surrounding Environment ◽  
Self Tuning ◽  
Tuning Circuit

<span>Wireless power transfer (WPT), through the transmission of contactless energy, is not only being used for charging batteries in smartphones, but it is also being increasingly used in the field of industrial applications. The capacitive based approach is utilized in this paper because of its ability to transmit power in a metal surrounding environment where the inductive-based approach failed to perform. This work focuses on the coupling study of a rotary CPT application where the power supply is stationary while the load rotates and therefore allows the load to rotate 360<sup>o</sup> free rotation. The Class E MOSFET power inverter is used here due to its ability to achieve high efficiency compared to other class of converters at high frequency. The prototype of the CPT for rotary application has also been successfully developed with disk plate thickness of 1mm-2mm. Overall, the developed CPT system for rotary application is able to deliver 5.5Watt with 83.33% efficiency. To enhance the power efficiency and ZVS conditions, a self-tuning circuit using phased-locked-loop has been proposed in this paper. The efficiency of the developed system with self-tuning circuit is increased to 97.%.</span>

FR-IR Molecular Microanalysis System

1990 ◽  
Vol 48 (2) ◽  
pp. 270-271
Author(s):  
John A. Reffner ◽  
William T. Wihlborg
Keyword(s):  
Fourier Transform ◽  
Fourier Transform Infrared ◽  
Integrated System ◽  
Morphological Examination ◽  
Fully Integrated ◽  
Ir Microscopy ◽  
Normal Functions ◽  
Infrared Microspectroscopy ◽  
Infrared Spectral ◽  
Ft Ir

The IRμs™ is the first fully integrated system for Fourier transform infrared (FT-IR) microscopy. FT-IR microscopy combines light microscopy for morphological examination with infrared spectroscopy for chemical identification of microscopic samples or domains. Because the IRμs system is a new tool for molecular microanalysis, its optical, mechanical and system design are described to illustrate the state of development of molecular microanalysis. Applications of infrared microspectroscopy are reviewed by Messerschmidt and Harthcock.Infrared spectral analysis of microscopic samples is not a new idea, it dates back to 1949, with the first commercial instrument being offered by Perkin-Elmer Co. Inc. in 1953. These early efforts showed promise but failed the test of practically. It was not until the advances in computer science were applied did infrared microspectroscopy emerge as a useful technique. Microscopes designed as accessories for Fourier transform infrared spectrometers have been commercially available since 1983. These accessory microscopes provide the best means for analytical spectroscopists to analyze microscopic samples, while not interfering with the FT-IR spectrometer’s normal functions.

Method of high frequency therapy at cows' mastitis during machine milking

2020 ◽  
pp. 9-12
Author(s):  
Viktor E. Lyubimov ◽  
Keyword(s):  
Dairy Cows ◽  
Electromagnetic Fields ◽  
High Frequency ◽  
High Efficiency ◽  
Environmentally Friendly ◽  
Ultrahigh Frequency ◽  
Machine Milking ◽  
High Frequency Electromagnetic Field ◽  
Milking Machine ◽  
Methods Of Treatment

Health of dairy cows ensures human health, so it is important that dairy products do not contain antibiotics that are used to treat any inflammation, including mastitis. In Russia at present, the problem of mastitis in cows exists with both attached and loose housing of cows. Mastitis of dairy cows are the great problem in milking husbandry. Losses from mastitis in milk yield can reach 15-20%. The main reasons for the occurrence of nonspecific mastitis of cows are the shortcomings of the working components of the milking machine: the degree of deterioration of the nipple rubber and the violation of machine milking technology (the reduction in pre-milking time and vacuum fluctuations account for 70% of all causes). Treatment of mastitis with antibiotics is effective, but not environmentally friendly and unacceptable. For the treatment of inflammation of the udder, it is necessary to use more environmentally friendly methods of treatment, one of which is the exposure to ultra-high frequency electromagnetic field tested by medicine. Use of three types of medical-mobile milking machines with the same method of exposure to ultrahigh-frequency electromagnetic fields on cow's nipples through electrodes in milking cups: LPDA-1-UHF, LPDA-2-UHF and LPDA-UHF-30 M, is described in the article. Author proved that cows with subclinical forms of mastitis recovered faster during milking with exposure to the ultrahigh frequency than when treated by antibiotics, and milking with the ultrahigh frequency device helps to recover 82% of the affected quarters with clinical forms and 100% of cows with subclinical forms of mastitis or with udder irritation. The high efficiency of the method of exposure to electromagnetic fields of the ultrahigh frequency during machine milking by means of medical-mobile milking machines LPDA-UHF for the prevention and treatment of mastitis of cows was shown.

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