LOW‐FREQUENCY IMPEDANCE PARAMETERS OF BASALT, GRANITE, AND QUARTZITE

Geophysics ◽  
1973 ◽  
Vol 38 (1) ◽  
pp. 68-75 ◽  
Author(s):  
A. S. Khalafalla ◽  
W. J. Maegley
Keyword(s):  
Room Temperature ◽  
Electrical Impedance ◽  
Analog Circuit ◽  
Low Frequency ◽  
Frequency Variation ◽  
Frequency Range ◽  
Argand Diagram ◽  
Circular Arcs ◽  
Impedance Parameters ◽  
Zero Frequency

An analog circuit digital computer setup was used to evaluate rock electrical impedance and phase angle in the frequency range 0.05 to 2 khz. Room‐temperature measurements were made on several samples of basalt, granite, and quartz. Argand diagram presentation of rock reactance as a function of its resistance at a series of frequencies described a semicircular arc. Rock impedance circular arcs can be used to define the rock resistivity at infinite frequency and the dc resistivity at the limit of zero frequency. Variation of rock resistance with the logarithm of frequency indicated finite rock dielectric dispersions at characteristic frequency ranges. Also, variation of rock reactance with the logarithm of frequency exhibited finite relaxation peaks, which can be used to difine the rock characteristics or turnover frequency as well as a characteristic or relaxation time.

Design and Application of a Low Frequency VCO

2014 ◽  
Vol 668-669 ◽  
pp. 808-811
Author(s):  
Hui Min Zhang ◽  
Qing Ping Wu ◽  
Zheng Yuan Zhou ◽  
Xun Wang
Keyword(s):  
Experimental Test ◽  
Input Signal ◽  
Operational Amplifier ◽  
Output Signal ◽  
Analog Circuit ◽  
Low Frequency ◽  
Voltage Controlled Oscillator ◽  
Frequency Range ◽  
Innovative Design ◽  
Design Cost

The low frequency voltage controlled oscillator (VCO) is designed using integrated operational amplifier. The frequency of the output signal of VCO changes with the magnitude of the input signal voltage, and show a linear relationship within a certain range through the experimental test. Experiments show that, under the input of certain amplitude and frequency range of the square wave, triangle wave, saw-tooth wave, the output waveform of VCO respectively is ambulance, fire siren and other kinds of ambulance siren Signal. This innovative design’ cost is low, realized by analog circuit. It can be used in the practice of teaching case, electronic production or development of sound panels.

scholarly journals Implementation of the Spectral Method for Determining of Measuring Instruments' Dynamic Characteristics

2020 ◽  
Vol 11 (2) ◽  
pp. 155-162
Author(s):  
A. F. Sabitov ◽  
I. A. Safina
Keyword(s):  
Dynamic Response ◽  
Spectral Method ◽  
Amplitude Spectrum ◽  
Low Frequency ◽  
Signal Amplitude ◽  
Measuring Instruments ◽  
Frequency Noise ◽  
Frequency Range ◽  
Calculated Amplitude ◽  
Zero Frequency

The spectral method for establishing dynamic response of measuring instruments basically requires determining the amplitude spectrum of the signal in its informative part that includes the amplitude spectrum at zero frequency. The operating frequency range of existing low-frequency spectrum analyzers is above zero frequency that leads to an uncertainty in dynamic response of measuring instruments determined by the spectral method. The purpose of this paper is to develop a program for calculating the signal amplitude spectrum, starting from zero frequency, to implement a spectral method for determining the dynamic response of measuring instruments on computers equipped with the MatLab package.To implement the spectral method for determining the dynamic response of measuring instruments, we developed a program in the MatLab 2013b environment that determines the signal amplitude spectrum from zero Hertz. The program reads the source data from Excel tables and presents the calculated amplitude spectrum as a chart and a report table.It is shown that the developed program calculates the signal amplitude spectrum with a standard deviation of not more than 3.4 % in the frequency range of 0 to 10 rad/s. The calculated amplitude spectrum allows determining the time constant of first-order aperiodic measuring instruments with an uncertainty of not more than 0.166 % at any noise level, if their frequencies are outside the information part of the spectrum.We demonstrated the claimed advantage of the spectral method for determining dynamic response using the developed program by the example of a high-frequency noise in the transient response of some measuring instruments.

scholarly journals Relationship between moisture content and electrical impedance of carrot slices during drying

2015 ◽  
Vol 29 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Ákos Kertész ◽  
Zuzana Hlaváčová ◽  
Eszter Vozáry ◽  
Lenka Staroňová
Keyword(s):  
Moisture Content ◽  
Electrical Impedance ◽  
Fruits And Vegetables ◽  
Physiological State ◽  
Impedance Measurement ◽  
Biological Tissues ◽  
Impedance Spectra ◽  
Frequency Range ◽  
Impedance Parameters ◽  
Precision Balance

Abstract Electrical properties of food materials can give information about the inner structure and physiological state of biological tissues. Generally, the process of drying of fruits and vegetables is followed by weight loss. The aim of this study was to measure the impedance spectra of carrot slices during drying and to correlate impedance parameters to moisture content in different drying periods. Cylindrical slices were cut out from the carrot root along the axis. The slices were dried in a Venticell 111 air oven at 50°C. The weight of the slices was measured with a Denver SI-603 electronic analytical and precision balance. The weighing of the samples was performed every 30 min at the beginning of drying and every 60 min after the process. The moisture content of the samples was calculated on wet basis. The magnitude and phase angle of electrical impedance of the slices were measured with HP 4284A and 4285A precision LCR meters in the frequency range from 30 Hz to 1 MHz and from 75 kHz to 30 MHz, respectively, at voltage 1 V. The impedance measurement was performed after weighting. The change in the magnitude of impedance during drying showed a good correlation with the change in the moisture content.

Propagation of Audiofrequency Sound in High Polymers

1950 ◽  
Vol 23 (1) ◽  
pp. 163-171
Author(s):  
R. S. Witte ◽  
B. A. Mrowca ◽  
E. Guth
Keyword(s):  
Room Temperature ◽  
Low Frequency ◽  
Intermolecular Forces ◽  
Temperature Curve ◽  
Frequency Range ◽  
Dynamic Measurements ◽  
Time Effects ◽  
And Shifts ◽  
Viscoelastic Constants ◽  
Made In

Abstract Velocity and attenuation measurements were made in thin strips of rubber from 0.5 to 5 kc and from −5° to 90° C to obtain the dynamic viscoelastic constants of Butyl and GR-S gum stocks. Above room temperature velocity and attenuation are higher in Butyl gum than in GR-S. In all cases, the velocity increases with decreasing temperature and increasing frequency. The attenuation shows a peak with temperature. For Butyl, the peaks are broad and occur at higher temperatures than for GR-S. For both stocks an increase in frequency gives peaks which are higher, sharper, and shifted to higher temperatures. In some instances, there are indications of peaks in the attenuation versus frequency at frequencies beyond our range of measurement. The behavior of the dynamic modulus in the temperature and frequency range studied is similar to that of the velocity. These results, combined with low temperature static measurements and very low frequency dynamic measurements, indicate a U-shaped modulus-temperature curve whose minimum broadens and shifts to higher temperatures with increasing frequency. This may be explained by a generalization of the kinetic theory of rubber elasticity, taking into account intra- and intermolecular forces, and considering time effects.

Dielectric and impedance spectroscopy of K+-doped MgAl2O4 nanoparticles

2018 ◽  
Vol 32 (15) ◽  
pp. 1850189
Author(s):  
Javed Ahmad ◽  
S. H. Bukhari ◽  
M. Qadeer Awan ◽  
M. Ehsan Mazhar ◽  
A. R. Makhdoom
Keyword(s):  
Dielectric Constant ◽  
Impedance Spectroscopy ◽  
High Frequency ◽  
Dielectric Response ◽  
Room Temperature ◽  
Parent Compound ◽  
Low Frequency ◽  
Space Charge Polarization ◽  
Relaxation Phenomena ◽  
Frequency Range

In this study, the dielectric response of Potassium (K[Formula: see text])-doped magnesium aluminates nanoparticles (Mg[Formula: see text]K[Formula: see text]Al2O4, x = 0.0, 0.25, 0.5, 0.75, 1.0) have been investigated as a function of frequency (20 Hz to 2 MHz) at room-temperature. Interestingly, the behavior of dielectric constant indicated the ionic or space charge polarization in the low-frequency range and it remains almost constant at high frequency. However, the value of conductivity increases at higher frequencies which is consistent with the previously reported results for the parent compound MgAl2O4. Moreover, the Cole–Cole plots represent various relaxation phenomena reflecting the existence of grain (boundaries) resistance effects.

Noise Spectra of Six Gey Bz:H Thermo-sensing Films for Micro-bolometers

2009 ◽  
Vol 1153 ◽  
Author(s):  
Andrey Kosarev ◽  
Ismael Cosme ◽  
Alfonso Torres
Keyword(s):  
Room Temperature ◽  
Low Frequency ◽  
Noise Spectrum ◽  
Frequency Range ◽  
Conductivity Activation Energy ◽  
Entire Frequency Range ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Increasing Temperature ◽  
Noise Spectra

AbstractNoise spectra in plasma deposited SixGeyBz:H thermo-sensing films for micro-bolometers have been studied. The samples were characterized by SIMS (composition) and conductivity (room temperature conductivity, activation energy) measurements. The noise spectra were measured in the temperature range from T= 300 K to T=400 K and in the frequency range from f=2 Hz to f=2×104 Hz. The noise spectra SI(f) for the samples Si0.11Ge0.88:H and Si0.04Ge0.71B0.23 can be described by SI(f) ˜ f– β with β = 1 and β = 0.4, respectively. For the sample Si0.06Ge0.67B0.26 two slopes were observed: in low frequency region f≤ 103 Hz β1= 0.7 and at higher frequencies f>103 Hz β2= 0.13. Increasing temperature resulted in an increase of noise magnitude and a change of β values. The latter depended on film composition. The correlation observed between noise and conductivity activation energies suggests that noise is due to bulk rather than interface processes. Noise spectrum of the thermo-sensing film Si0.11Ge0.88:H was compared with that for micro-bolometer structure with the same thermo-sensing film. The micro-bolometer structure showed higher noise value in entire frequency range that assumed additional processes inducing noise.

scholarly journals Dielectric properties of ternary composites of triblock polymer surfactant, liquid crystal and organic solvent

2014 ◽  
Vol 04 (03) ◽  
pp. 1450022 ◽  
Author(s):  
M. R. Fisch ◽  
Clinton Braganza ◽  
L. C. Chien ◽  
R. G. Petschek
Keyword(s):  
Liquid Crystal ◽  
Organic Solvent ◽  
Room Temperature ◽  
Low Frequency ◽  
Ternary Mixtures ◽  
Frequency Range ◽  
Getter Effect ◽  
Triblock Polymer ◽  
Polymer Surfactant ◽  
Triblock Polymers

Dielectric spectroscopy, at room temperature (20°C), is used to study the dielectric response of ternary mixtures of commercial nematic liquid crystal mixtures E7 and E33, an organic solvent N-Methyl-2-Pyrrolidone (NMP) and a triblock polymers in the frequency range from 0.01 Hz to 1 MHz. The results indicate a dielectric relaxation in the hectohertz region. Individually, both E7 and NMP have rather large low frequency conductivities; however, the low frequency (0.01–10 Hz) behavior of the mixtures has no such behavior. We attribute this behavior to an ion getter effect of the triblock polymer surfactant. Optimized ternary mixtures obtain a real dielectric constant near 230, and loss tangent less than 0.05 at frequencies near 10 mHz.

Experimental Study of Low-Frequency Effects on the Dynamic Modulus of a Buna-N Rubber

1955 ◽  
Vol 28 (1) ◽  
pp. 131-138 ◽  
Author(s):  
Allen Q. Hutton ◽  
A. W. Nolle
Keyword(s):  
Dynamic Modulus ◽  
Room Temperature ◽  
Temperature Scale ◽  
Dynamic Properties ◽  
Low Frequency ◽  
Frequency Range ◽  
Frequency Increase ◽  
Frequency Effects ◽  
Similar Compound ◽  
Linear Dynamic

Abstract The linear dynamic Young's modulus of a vulcanized Buna-N gum rubber was measured at frequencies of 0.05, 0.10, and 1.00 cps, in the temperature range − 22° C to 30° C, by a method in which a small differential sinusoidal elongation is superimposed on a 5 per cent static elongation. The width of the dispersion range on the temperature scale (the range in which the logarithm of the modulus increases steeply with decreasing temperature) is only about 10° C, contrasted with widths as great as 25° C found in previous measurements on a similar compound at frequencies of several kilocycles. The modulus-temperature plot shifts upward by only about 4° C per decade of frequency increase of the present range, contrasted with about 10° C per decade in the previous measurements at higher frequencies. It is concluded that this elastomer cannot be described properly by means of the “method of reduced variables”, in which the dynamic properties are ascribed to mechanisms having identical temperature dependence, and that the low-temperature behavior is governed by mechanisms distinct from those effective in the audio-frequency range at room temperature.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

Dynamic Damping and Stiffness Characteristics of the Rolling Tire

2001 ◽  
Vol 29 (4) ◽  
pp. 258-268 ◽  
Author(s):  
G. Jianmin ◽  
R. Gall ◽  
W. Zuomin
Keyword(s):  
Dynamic Behavior ◽  
Variable Parameter ◽  
Low Frequency ◽  
Vertical Load ◽  
Frequency Range ◽  
Inflation Pressure ◽  
Vehicle Simulation ◽  
Dynamic Damping ◽  
Speed Range ◽  
Stiffness Characteristics

Abstract A variable parameter model to study dynamic tire responses is presented. A modified device to measure terrain roughness is used to measure dynamic damping and stiffness characteristics of rolling tires. The device was used to examine the dynamic behavior of a tire in the speed range from 0 to 10 km/h. The inflation pressure during the tests was adjusted to 160, 240, and 320 kPa. The vertical load was 5.2 kN. The results indicate that the damping and stiffness decrease with velocity. Regression formulas for the non-linear experimental damping and stiffness are obtained. These results can be used as input parameters for vehicle simulation to evaluate the vehicle's driving and comfort performance in the medium-low frequency range (0–100 Hz). This way it can be important for tire design and the forecasting of the dynamic behavior of tires.

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