Experimental Measurement of Dynamic Bulk Modulus Using Holography

1985 ◽  
Vol 58 (2) ◽  
pp. 258-268 ◽  
Author(s):  
B. P. Holownia
Keyword(s):  
Bulk Modulus ◽  
Room Temperature ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Limiting Factor ◽  
Frequency Range ◽  
Holographic Method ◽  
Indirect Methods ◽  
Servo Valve ◽  
Hydraulic Servo

Abstract The results show that the dynamic bulk modulus for NBR at room temperature is about 50% higher than the static bulk modulus in the frequency range of 1–200 Hz. The limiting factor was the servo-valve used which does not give enough dynamic pressure fluctuations above 200 Hz to obtain accurate results of the dynamic bulk modulus. The holographic method discussed here offers a number of advantages over other methods used in measuring dynamic bulk modulus. (i) The samples are of realistic size and any soft spots in the sample which would distort the results can be immediately identified. (ii) Dynamic bulk modulus can be measured accurately in the frequency range of 1 Hz–1000 Hz or higher, provided the hydraulic servo-valve used can respond in the frequency range. Work is already in hand which extends this frequency range to 1200 Hz. (iii) The change of volume of the sample is a direct measurement unlike other indirect methods, therefore, there is more confidence in the results.

scholarly journals Geomagnetic pulsations in the Pc5/Pi3 frequency range and fluctuations of foF2 frequency

2019 ◽  
Author(s):  
Nadezda Yagova ◽  
Alexander Kozlovsky ◽  
Evgeny Fedorov ◽  
Olga Kozyreva
Keyword(s):  
Spatial Distribution ◽  
Critical Frequency ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Automatic Detection ◽  
Geomagnetic Pulsations ◽  
Frequency Range ◽  
Spectral Content ◽  
Using Data ◽  
Fof2 Critical Frequency

Abstract. Using data of the ionosonde in Sodankyla, (SOD, 67° N, 27° E, Finland), parameters of variations of foF2 critical frequency in the Pc5/Pi3 (1–5 mHz) frequency range are studied. For that, a technique of automatic detection of critical frequency from an ionogram is developed. The variations of foF2 are compared with the Pc5/Pi3 geomagnetic pulsations on the ground and in the magnetosphere. The variations of foF2 are in the majority of cases decoupled from the Pc5/Pi3 on the ground. Meanwhile, the analysis of geomagnetic and foF2 variations at SOD show intervals with noticeable coherence for both horizontal components. These coherent pulsations are predominantly registered in the afternoon MLT sector. Statistically, their spectral content, polarization and spatial distribution differs from those of background variations. Coherent pulsation tend to occur under moderate geomagnetic and auroral activity, SW speed, and dynamic pressure fluctuations. The fraction of coherent geomagnetic and foF2 pulsations is higher for the geomagnetic pulsations registered in the magnetosphere, than on the ground.

scholarly journals Photothermal, Photoelectric, and Photothermoelectric Effects in Bi-Sb Thin Films in the Terahertz Frequency Range at Room Temperature

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 76
Author(s):  
Mikhail K. Khodzitsky ◽  
Petr S. Demchenko ◽  
Dmitry V. Zykov ◽  
Anton D. Zaitsev ◽  
Elena S. Makarova ◽  
...  
Keyword(s):  
Thin Films ◽  
Terahertz Radiation ◽  
Room Temperature ◽  
Voltage Drop ◽  
Radiation Detection ◽  
Radiation Detectors ◽  
Thz Radiation ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Terahertz Frequency Range

The terahertz frequency range is promising for solving various practically important problems. However, for the terahertz technology development, there is still a problem with the lack of affordable and effective terahertz devices. One of the main tasks is to search for new materials with high sensitivity to terahertz radiation at room temperature. Bi1−xSbx thin films with various Sb concentrations seem to be suitable for such conditions. In this paper, the terahertz radiation influence onto the properties of thermoelectric Bi1−xSbx 200 nm films was investigated for the first time. The films were obtained by means of thermal evaporation in vacuum. They were affected by terahertz radiation at the frequency of 0.14 terahertz (THz) in the presence of thermal gradient, electric field or without these influences. The temporal dependencies of photoconductivity, temperature difference and voltage drop were measured. The obtained data demonstrate the possibility for practical use of Bi1−xSbx thin films for THz radiation detection. The results of our work promote the usage of these thermoelectric materials, as well as THz radiation detectors based on them, in various areas of modern THz photonics.

scholarly journals Dielectric Spectroscopy Analysis of Liquid Crystals Recovered from End-of-Life Liquid Crystal Displays

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2873
Author(s):  
Ana Barrera ◽  
Corinne Binet ◽  
Frédéric Dubois ◽  
Pierre-Alexandre Hébert ◽  
Philippe Supiot ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
End Of Life ◽  
Room Temperature ◽  
Liquid Crystal Displays ◽  
Dielectric Anisotropy ◽  
Frequency Range ◽  
Spectroscopy Analysis ◽  
Diamond Nanoparticles ◽  
Nematic Phases ◽  
Universal Law

In the present work, the dielectric properties of recycled liquid crystals (LCs) (non-purified, purified, and doped with diamond nanoparticles at 0.05, 0.1, and 0.2 wt%) were investigated. The studied LC mixtures were obtained from industrial recycling of end-of-life LC displays presenting mainly nematic phases. Dielectric measurements were carried out at room temperature on a frequency range from 0.1 to 106 Hz using an impedance analyzer. The amplitude of the oscillating voltage was fixed at 1 V using cells with homogeneous and homeotropic alignments. Results show that the dielectric anisotropy of all purified samples presents positive values and decreases after the addition of diamond nanoparticles to the LC mixtures. DC conductivity values were obtained by applying the universal law of dielectric response proposed by Jonscher. In addition, conductivity of the doped LC mixtures is lower than that of the undoped and non-purified LC.

High Frequency Dielectric Response of the Ionic Liquid N-Methyl-N-ethylpyrrolidinium Dicyanamide

2007 ◽  
Vol 60 (1) ◽  
pp. 6 ◽  
Author(s):  
Simon Schrödle ◽  
Gary Annat ◽  
Douglas R. MacFarlane ◽  
Maria Forsyth ◽  
Richard Buchner ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Dielectric Loss ◽  
Dielectric Relaxation ◽  
High Frequency ◽  
Dielectric Response ◽  
Room Temperature ◽  
Room Temperature Ionic Liquid ◽  
Dielectric Relaxation Spectroscopy ◽  
Frequency Range ◽  
Fast Rotation

A study of the room-temperature ionic liquid N-methyl-N-ethylpyrrolidinium dicyanamide by dielectric relaxation spectroscopy over the frequency range 0.2 GHz ≤ ν ≤ 89 GHz has revealed that, in addition to the already known lower frequency processes, there is a broad featureless dielectric loss at higher frequencies. The latter is probably due to the translational (oscillatory) motions of the dipolar ions of the IL relative to each other, with additional contributions from their fast rotation.

Research on the Impact Pressure of the Hydraulic Rolling-Cut Shear

2010 ◽  
Vol 145 ◽  
pp. 410-413 ◽  
Author(s):  
Jing Wang ◽  
He Yong Han ◽  
Qing Xue Huang ◽  
Jun Wang
Keyword(s):  
Hydraulic System ◽  
Impact Pressure ◽  
Direct Impact ◽  
Actual Situation ◽  
Work Situation ◽  
Servo Valve ◽  
Indirect Impact ◽  
Hydraulic Servo ◽  
Hydraulic Servo System ◽  
The Impact

The reasons for impact pressure are obtained by the research the hydraulic system of Hydraulic Rolling-Cut Shear. The impact pressure of hydraulic system is divided into direct impact and indirect impact. Based on analyzing the actual situation the measures should be taken to reduce the impact pressure when design hydraulic system. The suitable length of pipeline can improve the performance of the hydraulic system because the length is important for the impact pressure. The accumulator can absorb impact pressure and improve the work situation of servo valve. Therefore, the suitable accumulators should be set in the hydraulic system. The study provides theory basis for the pipe design of large hydraulic servo system.

scholarly journals STUDY OF PROCESSES OF PRESSURE AND IMPULSE FREQUENCY INFLUENCE ON PENETRATION OF LIQUIDS IN THE SAND SAMPLES

2016 ◽  
pp. 120-125
Author(s):  
M. Ya. Habibullin ◽  
R. R. Shangareyev
Keyword(s):  
Experimental Data ◽  
Oil Recovery ◽  
Pressure Fluctuations ◽  
Experimental Studies ◽  
Regression Equations ◽  
Linear Variation ◽  
Frequency Range ◽  
Impulse Frequency ◽  
Overburden Pressure

The article deals with the issues related to the hydrocarbon reservoirs oil recovery enhancement. It describes the bench laboratory experimental studies. The results obtained during determination of fluid leakage through the rock samples and the amount of absorption of pressure fluctuations at various regime parameters are presented. Using the experimental data the regression analysis was performed on the basis of which the qualitative correlations between factorial and resultant features were identified. Using the regression equations the graphic relations were constructed. It was found that with increasing the oscillation frequency of the fluid the amount of fluid passing through the sample of porous medium increased, with the highest value of q reached at the frequency range of 600 ... 1000 Hz. With increase in the oscillations penetration depth the absorption of the amplitude of the pressure fluctuations corresponds to the linear decrease, and with the overburden pressure increase the linear variation of absorption is distorted.

scholarly journals Подвижность ионных носителей заряда в пьезоэлектрических кристаллах Li-=SUB=-2-=/SUB=-B-=SUB=-4-=/SUB=-O-=SUB=-7-=/SUB=-

2020 ◽  
Vol 62 (3) ◽  
pp. 386
Author(s):  
Н.И. Сорокин ◽  
Ю.В. Писаревский ◽  
В.В. Гребенев ◽  
В.А. Ломонов
Keyword(s):  
Crystal Lattice ◽  
Carrier Mobility ◽  
Room Temperature ◽  
Lithium Ion ◽  
Structural Data ◽  
Crystallographic Axis ◽  
Frequency Range ◽  
Impedance Measurements ◽  
Structural Mechanism ◽  
Ag Electrodes

The impedance measurements of Li2B4O7 single crystal with Ag electrodes in the frequency range 1-3*107 Hz at room temperature have been made. The Li2B4O7 crystal (sp. gr. I41cd, Z = 8) was oriented along crystallographic axis c. Contributions from the bulk crystal and crystal / electrode boundaries in the impedance hodograph of the Ag | Li2B4O7 | Ag system were selected. The structural mechanism of lithium-ion transport in Li2B4O7 has been discussed. Based on electrophysical and structural data, the conductivity σdc = 2.3 × 10–9 S / cm, carrier mobility (vacancies VLi) μmob = 6 × 10−10 cm2 / sV and their concentration nmob = 2.4 × 1019 cm – 3 (0.14% of the amount of lithium in the crystal lattice) have been determined.

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