scholarly journals A review of high frequency emission in 2-150 kHz range

2020 ◽  
Vol 9 (2) ◽  
pp. 132
Author(s):  
Tomina Thomas ◽  
Prawin Angel Michael
Keyword(s):  
Energy Saving ◽  
Power Quality ◽  
High Frequency ◽  
High Frequencies ◽  
Embedded Generation ◽  
Frequency Emission

This paper reviews state-of part of discussion that concern about high frequency emission. Sometimes there may be emission in the range of high frequencies because of the fast improvement of energy saving equipments in our homes. Investigators and standardized organization given a very much importance to the disturbances of power quality that occur in the range middle of 2-150 kHz. Disturbances of these high frequencies are becoming an increasing concern in the industry, particularly due to the growth of distributed and embedded generation. Now days, a large number of researches are proceeding at a large number of places, yet information regarding supraharmonics remains confined.

scholarly journals Rheology of rounded mammalian cells over continuous high-frequencies

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gotthold Fläschner ◽  
Cosmin I. Roman ◽  
Nico Strohmeyer ◽  
David Martinez-Martin ◽  
Daniel J. Müller
Keyword(s):  
High Frequency ◽  
Mammalian Cells ◽  
Mechanical Response ◽  
Cell Mass ◽  
Low Frequency ◽  
Mass Measurements ◽  
High Frequencies ◽  
Polymer Relaxation ◽  
Continuous Frequency ◽  
Rheological Experiments

AbstractUnderstanding the viscoelastic properties of living cells and their relation to cell state and morphology remains challenging. Low-frequency mechanical perturbations have contributed considerably to the understanding, yet higher frequencies promise to elucidate the link between cellular and molecular properties, such as polymer relaxation and monomer reaction kinetics. Here, we introduce an assay, that uses an actuated microcantilever to confine a single, rounded cell on a second microcantilever, which measures the cell mechanical response across a continuous frequency range ≈ 1–40 kHz. Cell mass measurements and optical microscopy are co-implemented. The fast, high-frequency measurements are applied to rheologically monitor cellular stiffening. We find that the rheology of rounded HeLa cells obeys a cytoskeleton-dependent power-law, similar to spread cells. Cell size and viscoelasticity are uncorrelated, which contrasts an assumption based on the Laplace law. Together with the presented theory of mechanical de-embedding, our assay is generally applicable to other rheological experiments.

Advanced High Frequency AC Microgrid with integrated power quality conditioning capability

2009 ◽  
Author(s):  
Fredi Z. Ferrigolo ◽  
Diego B. Ramos ◽  
Jeferson M. Correa ◽  
Felix A. Farret ◽  
Luciano P. Lima
Keyword(s):  
Power Quality ◽  
High Frequency ◽  
High Frequency Ac ◽  
Ac Microgrid

Effect of mastoid drilling on hearing of the contralateral ear

2013 ◽  
Vol 127 (10) ◽  
pp. 952-956 ◽  
Author(s):  
A Goyal ◽  
P P Singh ◽  
A Vashishth
Keyword(s):  
Hearing Loss ◽  
High Frequency ◽  
Otoacoustic Emissions ◽  
Pure Tone Audiometry ◽  
Otoacoustic Emission ◽  
Prospective Clinical Study ◽  
Distortion Product Otoacoustic Emission ◽  
High Frequencies ◽  
Distortion Product ◽  
Contralateral Ear

AbstractObjectives:This study aimed to: understand the effect that high intensity noise associated with drilling (during otological surgery) has on hearing in the contralateral ear; determine the nature of hearing loss, if any, by establishing whether it is temporary or persistent; and examine the association between hearing loss and various drill parameters.Methods:A prospective clinical study was carried out at a tertiary centre. Thirty patients with unilateral cholesteatoma and normal contralateral hearing were included. Patients were evaluated pre-operatively and for five days following surgery using high frequency pure tone audiometry, and low and high frequency transient evoked and distortion product otoacoustic emission testing.Results:The findings revealed statistically significant changes in distortion product otoacoustic emissions at high frequencies (p = 0.016), and in transient evoked otoacoustic emissions at both low and high frequencies (p = 0.035 and 0.021, respectively). There was a higher statistical association between otoacoustic emission changes and cutting burrs compared with diamond burrs.Conclusion:Drilling during mastoid surgery poses a threat to hearing in the contralateral ear due to noise and vibration conducted transcranially.

Energy Saving Control Strategy for the High-Frequency Start-up Process for Electric Mining Haul Trucks

2018 ◽  
Vol 3 (4) ◽  
pp. 595-606 ◽  
Author(s):  
Yingjie Zhang ◽  
Ying Zhang ◽  
Zhaoyang Ai ◽  
Yun Feng ◽  
Wei Cheng ◽  
...  
Keyword(s):  
Energy Saving ◽  
Control Strategy ◽  
High Frequency ◽  
Start Up ◽  
Energy Saving Control

scholarly journals The Estimation of Hydrometeor Profiles from Wideband Microwave Observations

2000 ◽  
Vol 39 (10) ◽  
pp. 1645-1656 ◽  
Author(s):  
Gail M. Skofronick-Jackson ◽  
James R. Wang
Keyword(s):  
High Frequency ◽  
Cloud Water ◽  
Tropical Ocean ◽  
Low Frequencies ◽  
High Frequencies ◽  
Atmospheric Research ◽  
Brightness Temperatures ◽  
Microphysical Properties ◽  
Ice Microphysics ◽  
Updraft Region

Abstract Profiles of the microphysical properties of clouds and rain cells are essential in many areas of atmospheric research and operational meteorology. To enhance the understanding of the nonlinear and underconstrained relationships between cloud and hydrometeor microphysical profiles and passive microwave brightness temperatures, estimations of cloud profiles for an anvil region, a convective region, and an updraft region of an oceanic squall were performed. The estimations relied on comparisons between radiative transfer calculations of incrementally estimated microphysical profiles and concurrent dual-altitude wideband brightness temperatures from the 22 February 1993 flight during the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment. The wideband observations (10–220 GHz) are necessary for estimating cloud profiles reaching up to 20 km. The low frequencies enhance the rain and cloud water profiles, and the high frequencies are required to detail the higher-altitude ice microphysics. A microphysical profile was estimated for each of the three regions of the storm. Each of the three estimated profiles produced calculated brightness temperatures within ∼10 K of the observations. A majority of the total iterative adjustments were to the estimated profile’s frozen hydrometeor characteristics and were necessary to match the high-frequency calculations with the observations. This requirement indicates a need to validate cloud-resolving models using high frequencies. Some difficulties matching the 37-GHz observation channels on the DC-8 and ER-2 aircraft with the calculations simulated at the two aircraft heights (∼11 km and 20 km, respectively) were noted, and potential causes were presented.

Discrete-Time H-Infinity Synthesis of Frequency-Shaped Sliding Mode Control for Suppression of Vibration With Multiple Peak Frequencies

2016 ◽  
Author(s):  
Minghui Zheng ◽  
Masayoshi Tomizuka
Keyword(s):  
High Frequency ◽  
Sliding Mode ◽  
Disk Drive ◽  
Sliding Surface ◽  
Surface Dynamics ◽  
H Infinity ◽  
High Frequencies ◽  
Multiple Peak ◽  
Significant Performance ◽  
The Stability

Vibration with multiple large peaks at high frequencies may cause significant performance degradation and have become a major concern in modern high precision control systems. To deal with such high-frequency peaks, it is proposed to design a frequency-shaped sliding mode controller based on H∞ synthesis. It obtains an ‘optimal’ filter to shape the sliding surface, and thus provides frequency-dependent control allocation. The proposed frequency-shaping method assures the stability in the presence of multiple-peak vibration sources, and minimizes the weighted H∞ norm of the sliding surface dynamics. The evaluation is performed on a simulated hard disk drive with actual vibration sources from experiments, and the effectiveness of large vibration peak suppression is demonstrated.

scholarly journals Activity and cytosolic Na+ regulates synaptic vesicle endocytosis

2019 ◽  
Author(s):  
Yun Zhu ◽  
Dainan Li ◽  
Hai Huang
Keyword(s):  
Synaptic Transmission ◽  
High Frequency ◽  
Synaptic Vesicles ◽  
Glutamate Uptake ◽  
High Frequencies ◽  
Vesicle Recycling ◽  
Two Photon ◽  
Readily Releasable Pool ◽  
Content Change ◽  
Intracellular Ca

ABSTRACTRetrieval of synaptic vesicles via endocytosis is essential for maintaining sustained synaptic transmission, especially for neurons that fire action potentials at high frequencies. However, how activity regulates synaptic vesicles recycling is largely unknown. Here we report that Na+ substantially accumulated in the mouse calyx of Held terminals during repetitive high-frequency spiking. Elevated presynaptic Na+ accelerated both slow and rapid forms of endocytosis and facilitated endocytosis overshoot but did not affect the readily releasable pool size, Ca2+ influx, or exocytosis. To examine whether this facilitation of endocytosis is related to the Na+-dependent vesicular content change, we dialyzed increasing concentrations of glutamate into the presynaptic cytosol or blocked the vesicular glutamate uptake with bafilomycin and found the rate of endocytosis was not affected by regulating the glutamate content in the presynaptic terminal. Endocytosis is critically dependent on intracellular Ca2+, and the activity of Na+/Ca2+ exchanger (NCX) may be altered when the Na+ gradient is changed. However, neither NCX blocker nor change of extracellular Na+ concentration affected the endocytosis rate. Moreover, two-photon Ca2+ imaging showed that presynaptic Na+ did not affect the action potential-evoked intracellular Ca2+ transient and decay. Therefore, we revealed a novel mechanism of cytosolic Na+ in accelerating vesicle endocytosis. During high-frequency synaptic transmission, when large amounts of synaptic vesicles are fused, Na+ accumulated in terminals, facilitated vesicle recycling and sustained reliable synaptic transmission.

scholarly journals ANALYSIS OF HIGH-FREQUENCY C-CORE MAGNETIC FLUX LEAKAGES FOR BONE TUMOR WITH INDUCTION HEATING BY USING MULTI-COIL

2019 ◽  
Author(s):  
Metharak Jokpudsa ◽  
Supawat Kotchapradit ◽  
Chanchai Thongsopa ◽  
Thanaset Thosdeekoraphat
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Tumor Tissue ◽  
Low Frequency ◽  
Heat Energy ◽  
High Frequencies ◽  
Frequency Magnetic Field ◽  
High Frequency Magnetic Field ◽  
The Magnetic Field ◽  
Flux Leakage

High-frequency magnetic field has been developed pervasively. The induction of heat from the magnetic field can help to treat tumor tissue to a certain extent. Normally, treatment by the low-frequency magnetic field needed to be combined with magnetic substances. To assist in the induction of magnetic fields and reduce flux leakage. However, there are studies that have found that high frequencies can cause heat to tumor tissue. In this paper present, a new magnetic application will focus on the analysis of the high-frequency magnetic nickel core with multi-coil. In order to focus the heat energy using a high-frequency magnetic field into the tumor tissue. The magnetic coil was excited by 915 MHz signal and the combination of tissues used are muscle, bone, and tumor. The magnetic power on the heating predicted by the analytical model, the power loss density (2.98e-6 w/m3) was analyzed using the CST microwave studio.

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 Novel Negative Capacitance and Conductance in All Temperatures and Voltages of Au/CNTs/n-Si/Al at Low and High Frequencies

2021 ◽  
Author(s):  
A. Ashery ◽  
Samia Gad ◽  
A. E.H. Gaballah ◽  
G. M. Turky
Keyword(s):  
Carbon Nanotube ◽  
High Frequency ◽  
Series Resistance ◽  
Negative Capacitance ◽  
Donor Concentration ◽  
Low Frequencies ◽  
High Frequencies ◽  
Depletion Width ◽  
Density Surface ◽  
P Type

Abstract The structure of carbon nanotube CNTs functioning as p-type material deposited over n-type silicon to produce heterojunction of Au/CNTs/n-Si/Al is presented in this study.This work explored the capacitance and conductance at various frequencies, temperatures, and voltages, the novelty here is that negative capacitance and conductance were observed at high frequencies in all temperatures and voltages, whereas capacitance appeared at both high and low frequencies, such as (2x107,1x107,1x102,10) Hz. At high-frequency f = 2x107 Hz, the capacitance raises while the conductance decreases; at all temperatures and voltages, the capacitance and conductance exhibit the same behavior at particular frequencies such as 1x106,1x105,1x104,1x103Hz, however their behavior differs at 2x107,1x107, 1x102 and 10Hz. Investigating the reverse square capacitance with voltage yielded the energy fermi (Ef), density surface of states (Nss), depletion width (Wd), barrier height, series resistance, and donor concentration (Nd)

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