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 On the measurement of alternating electric currents of high frequency

1914 ◽  
Vol 90 (622) ◽  
pp. 621-633 ◽  
Keyword(s):  
High Frequency ◽  
High Water ◽  
Point Of View ◽  
The Self ◽  
Wide Field ◽  
High Frequencies ◽  
Current Voltage ◽  
Improved Methods ◽  
Methods Of Measurement ◽  
Frequency Current

Both from the scientific and practical point of view the accurate measurements of alternating current, voltage and power at high frequencies is of considerable importance. For example, in the domain of pure science the study of energy losses in dielectrics at high frequencies is most interesting, while on the practical side, in radiotelegraphy, there is a wide field for improved methods of measurement. At frequencies from 100,000 to 2,000,000 ∼ per second by the methods at present in use it is comparatively easy to measure currents of the order of 0.1 ampère, but many difficulties present themselves when we have to deal with currents of 1 to 50 or 100 ampère. We have recently investigated several ways of measuring these larger currents, and the object of the present paper is to give a description of the more satisfactory methods and the results obtained by them. Thermal Instruments .-the most common method of measuring a high frequency current is to pass it through a conductor and observe the rise of temperature of this as shown by its expansion or change of resistance, or by means of one or more thermojunctions in contact with it or near it. The last method, that of a better and separate thermopile, was investigated by one of us many years ago and was later to measure the voltages induced in small search coils by alternating magnectc fields. The separate heater system was used by Mr. Duddell in his beautiful application of Mr. Boy's radiomicrometer to current measurement;and his thermo-galvanometer still represents the high-water mark in efficiency. While, however, the self-contained thermojuction and moving coil no doubt give the highest efficient, the use of a thermopile connected to a separate galvanometer has several advantages, especially in laboratories where economy of instruments has to be considered. A variety of heaters and thermopiles can be used with a single galvanometer, and both the sensitivity and the promptness can usually be altered within pretty wide limits by adding resistance to the galvanometer circuit.

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.

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.

Hearing Loss and Hearing Handicap in Users of Recreational Firearms

2002 ◽  
Vol 13 (03) ◽  
pp. 160-168 ◽  
Author(s):  
Michael Stewart ◽  
Rebecca Pankiw ◽  
Mark E. Lehman ◽  
Thomas H. Simpson
Keyword(s):  
Hearing Loss ◽  
American Academy ◽  
High Frequency ◽  
Pure Tone ◽  
Occupational Safety ◽  
Occupational Safety And Health ◽  
Gender Effects ◽  
The Self ◽  
Safety And Health ◽  
Hearing Handicap

This investigation sought to establish the prevalence of hearing loss and hearing handicap in a population of 232 recreational firearm users. Hearing handicap was calculated based on four methods using pure-tone threshold data from the American Academy of Ophthalmology and Otolaryngology, American Academy of Otolaryngology-Head and Neck Surgery, National Institute of Occupational Safety and Health, and American Speech-Language and Hearing Association in addition to the self-report Hearing Handicap Inventory for Adults-Screener (HHIA-S). Subjects (45 female and 187 male) ranging in age from 13 to 77 years (mean = 40 years, SD = 15.1) completed a short questionnaire regarding demographics and shooting practices followed by pure-tone air audiometry at Occupational Safety and Health Administration test frequencies of 500 to 6000 Hz. A total of 177 who exhibited varying degrees of hearing loss also received a face-to-face administration of the HHIA-S. Audiometric and HHIA-S results revealed that both high-frequency hearing loss and hearing handicap varied significantly as functions of age and occupation. Significant gender effects were observed audiometrically but not as a function of hearing handicap. HHIA-S scores varied significantly as a function of high-frequency (1000–4000 Hz) hearing loss. Correlation coefficients between the four different pure-tone methods of calculating hearing handicap and the self-reported HHIA-S were highest for pure-tone methods that do not employ 500 Hz in the calculation.

scholarly journals Influence of Parasitic Parameters on DC–DC Converters and Their Method of Suppression in High Frequency Link 35 kV PV Systems

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3743
Author(s):  
Rui Li ◽  
Fangyuan Shi ◽  
Xu Cai ◽  
Haibo Xu
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
Pv System ◽  
Zero Voltage Switching ◽  
Pv Systems ◽  
Magnetic Inductance ◽  
Parasitic Parameters ◽  
Saturable Inductor ◽  
Secondary Side ◽  
Pv Power Generation

Photovoltaic (PV) power generation has shown a trend towards large-scale medium- or high-voltage integration in recent years. The development of high-frequency link PV systems is necessary for the further improvement of system efficiency and the reduction of system cost. In the system, high-frequency high-step-up ratio LLC converters are one of the most important parts. However, the parasitic parameters of devices lead to a loss of zero-voltage switching (ZVS) in the LLC converter, greatly reducing the efficiency of the system, especially in such a high-frequency application. In this paper, a high-frequency link 35 kV PV system is presented. To suppress the influences of parasitic parameters in the LLC converter in the 35 kV PV system, the influence of parasitic parameters on ZVS is analyzed and expounded. Then, a suppression method is proposed to promote the realization of ZVS. This method adds a saturable inductor on the secondary side to achieve ZVS. The saturable inductor can effectively prevent the parasitic elements of the secondary side from participating in the resonance of the primary side. The experimental results show that this method achieves a higher efficiency than the traditional method by reducing the magnetic inductance.

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.

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