scholarly journals ADJUSTMENT OF RESONANCE FREQUENCY IN H-STRUCTURES ACCELERATING

2021 ◽  
pp. 64-67
Author(s):  
S.O. Vdovin ◽  
Ye.V. Gusev ◽  
L.D. Lobzov ◽  
O.P. Podolayk ◽  
M.G. Shulika
Keyword(s):  
Resonant Frequency ◽  
Resonance Frequency ◽  
High Frequency ◽  
Rf Power ◽  
Linear Accelerators ◽  
Input Devices ◽  
Temperature Mode ◽  
Accelerating Structure ◽  
And Control

It is necessary to adjust the resonant frequency of the accelerating structures during operation of high-frequency linear accelerators on the H-wave. The deviation of the resonant frequency of the resonator from the calculated value is due to the connection of input devices and control of RF power when changing the level of matching of the resonator with the feeder line that transports the RF power to the resonator, as well as when changing the temperature mode of the resonator. The problem is especially urgent when the accelerator structure consists of several resonators. The paper presents the designs of several resonant frequency tuners and the results of their research. The influence of the change of the frequency of oscillations excited in the accelerating structure on the parameters of the accelerated beam is considered.

Case study: Simulation and control of high frequency noise for commercial vehicle cab considering leak

2019 ◽  
Vol 67 (4) ◽  
pp. 315-329
Author(s):  
Rongjiang Tang ◽  
Zhe Tong ◽  
Weiguang Zheng ◽  
Shenfang Li ◽  
Li Huang
Keyword(s):  
High Frequency ◽  
Commercial Vehicle ◽  
Frequency Noise ◽  
High Frequency Noise ◽  
Simulation And Control ◽  
And Control

Terahertz Radiators Based on Si~3C-SiC MQW IMPATT Diodes

2020 ◽  
Vol 10 (4) ◽  
pp. 501-506
Author(s):  
Monisha Ghosh ◽  
Arindam Biswas ◽  
Aritra Acharyya
Keyword(s):  
High Frequency ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Noise Performance ◽  
Rf Power ◽  
Drift Diffusion ◽  
Frequency Bands ◽  
Atmospheric Window ◽  
Lower Noise ◽  
Impatt Diodes

Aims:: The potentiality of Multiple Quantum Well (MQW) Impacts Avalanche Transit Time (IMPATT) diodes based on Si~3C-SiC heterostructures as possible terahertz radiators have been explored in this paper. Objective:: The static, high frequency and noise performance of MQW devices operating at 94, 140, and 220 GHz atmospheric window frequencies, as well as 0.30 and 0.50 THz frequency bands, have been studied in this paper. Methods: The simulation methods based on a Self-Consistent Quantum Drift-Diffusion (SCQDD) model developed by the authors have been used for the above-mentioned studies. Results: Thus the noise performance of MQW DDRs will be obviously better as compared to the flat Si DDRs operating at different mm-wave and THz frequencies. Conclusion:: Simulation results show that Si~3C-SiC MQW IMPATT sources are capable of providing considerably higher RF power output with the significantly lower noise level at both millimeter-wave (mm-wave) and terahertz (THz) frequency bands as compared to conventional flat Si IMPATT sources.

scholarly journals A Study of Wideband Energy Reflectance in Patients with Otosclerosis: Data from a Chinese Population

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Suju Wang ◽  
Wenyang Hao ◽  
Chunxiao Xu ◽  
Daofeng Ni ◽  
Zhiqiang Gao ◽  
...  
Keyword(s):  
Resonance Frequency ◽  
Racial Differences ◽  
Chinese Population ◽  
Ambient Pressure ◽  
Control Group ◽  
Age And Gender ◽  
Significant Difference ◽  
And Gender ◽  
And Control ◽  
Peak Pressures

Objective(s). The purpose of this study was to explore the effectiveness of wideband acoustic immittance (WAI) in the diagnosis of otosclerosis by comparing the differences in the energy reflectance (ER) of WAI between patients with otosclerosis and age- and gender-matched normal hearing controls in the Chinese population. Methods. Twenty surgically confirmed otosclerotic ears were included in the otosclerotic group. The ER of WAI at ambient and peak pressures, resonance frequency, and 226-Hz tympanogram were collected prior to surgery using a Titan hearing test platform (Interacoustics A/S, Middelfart, Denmark). All diagnoses of otosclerosis in the tested ear were confirmed by surgery after the measurements. Thirteen normal adults (26 ears) who were age- and gender-matched with the otosclerotic patients were included as the control group. Results. At peak pressure, the ERs of otosclerotic patients were higher than those of the control group for frequencies less than 4,000Hz and were lower for frequencies greater than 4,000Hz. In addition, within the analyzed frequencies, the differences observed at 2,520Hz was statistically significant (p<0.05/16=0.003, Bonferroni corrected). At ambient pressure, the differences observed at 1,260 and 6,350Hz were statistically significant (p<0.05/16=0.003, Bonferroni corrected). Although the differences between the otosclerotic and control groups exhibited similar trends to those in studies implemented in Caucasian populations, the norms in the present study in the control group were different from those in the Caucasian populations, suggesting racial differences in WAI test results. Regarding the middle ear resonance frequency, no significant difference was observed between the two groups (P>0.05). Conclusion. WAI can provide valuable information for the diagnosis of otosclerosis in the Chinese population. Norms and diagnostic criteria corresponding to the patient’s racial group are necessary to improve the efficiency of WAI in the diagnosis of otosclerosis.

Testing of Sonic-Absorbent Panels’ Behavior in Open-Air Environment

2012 ◽  
Author(s):  
Petru A. Pop ◽  
Patricia A. Ungur ◽  
Liviu Lazar ◽  
Mircea Gordan ◽  
Florin M. Marcu
Keyword(s):  
High Frequency ◽  
Noise Pollution ◽  
Sound Level ◽  
Sound Level Meter ◽  
Data Logger ◽  
Public Buildings ◽  
Gypsum Plaster ◽  
Level Meter ◽  
And Control

One wildly used method to reduce and control the noise pollution in green city’s buildings is using sonic-absorbent panels. Their applications can be multiple, such as the insulation of buildings, acoustic barriers and fences along the highway or in front of supermarkets, hospitals and other public buildings. This paper presents a method for testing the behavior of sonic-absorbent panels in open-air environment. The work represents a carrying on of previous research about absorbent materials from gypsum family, tested in lab conditions. The experiment setup used a dynamic installation and as a sample a stand formed by six sonic-absorbent panels from special modeling alpha-gypsum plaster. This installation has been composed of two loudspeakers for emitting the sound at a well-defined frequency by the first laptop, the microphone for detecting and transmitting the signal to the second laptop for analyzing and processing the data. All operations were performed using MATLAB Programs, while a Data Logger Sound Level Meter type CENTER 332 was put on near the microphone to compare both results. The first experiment of acoustic stand has been realized by setting up the installation at a frequency from 50 Hz to 1250 Hz and altering the distance between loudspeakers and stand at 0.5m to 1m and 1.5m, respectively. The second experiment kept the same test’s conditions, while two and three layers of sonic-absorbent panels formed the stand, respectively, but at same distance from source of 0.5 m. In both tests, the results underlined the good sonic-absorbent properties of these panels, especially at medium and high frequency, which can recommend using the panels for multiple outside applications.

Rate-dependent shortening of action potential duration increases ventricular vulnerability in failing rabbit heart

2011 ◽  
Vol 300 (2) ◽  
pp. H565-H573 ◽  
Author(s):  
Masahide Harada ◽  
Yukiomi Tsuji ◽  
Yuko S. Ishiguro ◽  
Hiroki Takanari ◽  
Yusuke Okuno ◽  
...  
Keyword(s):  
Action Potential ◽  
High Frequency ◽  
Rabbit Heart ◽  
Left Ventricular ◽  
High Frequency Stimulation ◽  
Electrophysiological Properties ◽  
Rate Dependent ◽  
Frequency Stimulation ◽  
And Control

Congestive heart failure (CHF) predisposes to ventricular fibrillation (VF) in association with electrical remodeling of the ventricle. However, much remains unknown about the rate-dependent electrophysiological properties in a failing heart. Action potential properties in the left ventricular subepicardial muscles during dynamic pacing were examined with optical mapping in pacing-induced CHF ( n = 18) and control ( n = 17) rabbit hearts perfused in vitro. Action potential durations (APDs) in CHF were significantly longer than those observed for controls at basic cycle lengths (BCLs) >1,000 ms but significantly shorter at BCLs <400 ms. Spatial APD dispersions were significantly increased in CHF versus control (by 17–81%), and conduction velocity was significantly decreased in CHF (by 6–20%). In both groups, high-frequency stimulation (BCLs <150 ms) always caused spatial APD alternans; spatially concordant alternans and spatially discordant alternans (SDA) were induced at 60% and 40% in control, respectively, whereas 18% and 82% in CHF. SDA in CHF caused wavebreaks followed by reentrant excitations, giving rise to VF. Incidence of ventricular tachycardia/VFs elicited by high-frequency dynamic pacing (BCLs <150 ms) was significantly higher in CHF versus control (93% vs. 20%). In CHF, left ventricular subepicardial muscles show significant APD shortenings at short BCLs favoring reentry formations following wavebreaks in association with SDA. High-frequency excitation itself may increase the vulnerability to VF in CHF.

scholarly journals Design Optimization of MEMS Based LLC Tunable Resonant Converter for Power Supplies on Chip

2013 ◽  
Vol 705 ◽  
pp. 258-263
Author(s):  
Fahimullah Khan ◽  
Yong Zhu ◽  
Jun Wei Lu ◽  
Dzung Dao
Keyword(s):  
Resonant Frequency ◽  
Resonance Frequency ◽  
Parallel Plate ◽  
Power Supplies ◽  
Resonant Converter ◽  
Load Variations ◽  
Leakage Inductance ◽  
Variable Capacitor ◽  
Numerical Software ◽  
On Chip

In this paper, a novel MEMS based LLC converter is proposed for on chip power supplies. The design is optimized based on commercially available Metal MUMPs process for fabrication. The resonant frequency is optimized at 20MHz and MEMS based variable capacitor is fabricated on the chip to tune the peak resonance frequency of circuit which varies due to the load variations. The Design is simulated in FEM based numerical software COMSOL and Intellisuite. According to analysis the magnetizing inductance of 42nH and leakage inductance of 40nH has been achieved from 16 mm2 rectangular coil transformer. The total capacitance of 1500pF has been achieved from parallel plate capacitors and variation of 3pF has been achieved from variable capacitor.

scholarly journals Nominal and Actual Values of Inductor and Capacitor Parameters at High Frequencies

2019 ◽  
Vol 7 (4) ◽  
pp. 44-53 ◽  
Author(s):  
E. V. Gurov ◽  
S. S. Uvaysov ◽  
A. S. Uvaysova ◽  
S. S. Uvaysova
Keyword(s):  
Resonant Frequency ◽  
High Frequency ◽  
The Self ◽  
Impedance Match ◽  
Analog Filters ◽  
Reactive Component ◽  
High Frequencies ◽  
Coil Inductance ◽  
Parasitic Parameters ◽  
Capacitor Capacitance

Coil inductance and capacitor capacitance depend on overall dimensions, structure, and ambient factors. They do not vary with frequency. Reactive component impedance is determined by inductance or capacitance respectively, if active resistance is not considered. This is true for the frequencies which are significantly lower than the self-resonant frequency of the component. Parasitic parameters contribution increases on approaching the self-resonant frequency. Therefore, the componentʼs actual inductance and actual capacitance on operating frequency are defined. They are provided by manufacturers and differ from the nominal values. The actual values provide more accurate impedance of components near the considered frequency. Significant deviation from the considered frequency can cause impedance mismatch even more than the nominal values can provide. Frequency response of the high-frequency circuits such as analog filters and impedance match networks are determined by components impedance, not the nominal values. Thus, calculated values must be close to the actual values. The purpose of this article is to justify actual values application instead of nominal values.

scholarly journals SPECIFICITY OF SIMULATION OF LOW ENERGIES ACCELERATING STRUCTURES

2019 ◽  
pp. 3-8
Author(s):  
S.A. Vdovin ◽  
Ye.V. Gussev
Keyword(s):  
Resonant Frequency ◽  
High Frequency ◽  
High Frequency Power ◽  
Low Energies ◽  
Acceleration Channel ◽  
Frequency Power

Parameters of the H-resonator: the resonant frequency, the distribution of phases and amplitudes of the highfrequency field in the accelerating gaps are mainly determined by the load that forms the acceleration channel. When creating applied accelerators based on H-resonators, it is necessary to determine not only the parameters of the accelerating channel, but also the electrodynamics characteristics of the resonator, which have influence on the efficiency of high-frequency power use. The paper presents an analysis of the methods for modeling the load of accelerating H-resonators taking into account the stated requirements.

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