LABORATORY MEASUREMENTS OF ABSORPTION BY WATER VAPOUR IN THE FREQUENCY RANGE 100 TO 1000 GHz

1980 ◽  
pp. 255-264 ◽  
Author(s):  
D.T. Llewellyn-Jones
Keyword(s):  
Water Vapour ◽  
Laboratory Measurements ◽  
Frequency Range

scholarly journals Bandwidth and Common Mode Optimization for Current and Voltage Sources in Bioimpedance Spectroscopy

2021 ◽  
Vol 12 (1) ◽  
pp. 135-146
Author(s):  
Tobias Menden ◽  
Jascha Matuszczyk ◽  
Steffen Leonhardt ◽  
Marian Walter
Keyword(s):  
Patient Safety ◽  
Current Source ◽  
The Body ◽  
Voltage Source ◽  
Bioimpedance Spectroscopy ◽  
Laboratory Measurements ◽  
Output Impedance ◽  
Frequency Range ◽  
Common Mode ◽  
High Bandwidth

Abstract Bioimpedance measurements use current or voltage sources to inject an excitation signal into the body. These sources require a high bandwidth, typically from 1 kHz to 1 MHz. Besides a low common mode, current limitation is necessary for patient safety. In this paper, we compare a symmetric enhanced Howland current source (EHCS) and a symmetric voltage source (VS) based on a non-inverting amplifier between 1 kHz and 1 MHz. A common mode reduction circuit has been implemented in both sources. The bandwidth of each source was optimized in simulations and achieved a stable output impedance over the whole frequency range. In laboratory measurements, the output impedance of the EHCS had its -3 dB point at 400 kHz. In contrast, the VS reached the +3 dB point at 600 kHz. On average over the observed frequency range, the active common mode compensation achieved a common mode rejection of -57.7 dB and -71.8 dB for the EHCS and VS, respectively. Our modifications to classical EHCS and VS circuits achieved a low common mode signal between 1 kHz and 1 MHz without the addition of complex circuitry, like general impedance converters. As a conclusion we found VSs to be superior to EHCSs for bioimpedance spectroscopy due to the higher bandwidth performance. However, this only applies if the injected current of the VS can be measured.

scholarly journals Water vapour foreign-continuum absorption in near-infrared windows from laboratory measurements

2012 ◽  
Vol 370 (1968) ◽  
pp. 2557-2577 ◽  
Author(s):  
Igor V. Ptashnik ◽  
Robert A. McPheat ◽  
Keith P. Shine ◽  
Kevin M. Smith ◽  
R. Gary Williams
Keyword(s):  
Water Vapour ◽  
Near Infrared ◽  
Prediction Models ◽  
Weather Prediction ◽  
Pair Interaction ◽  
Atmospheric Conditions ◽  
Laboratory Measurements ◽  
Atmospheric Absorption ◽  
Clear Sky ◽  
Long Time

For a long time, it has been believed that atmospheric absorption of radiation within wavelength regions of relatively high infrared transmittance (so-called ‘windows’) was dominated by the water vapour self-continuum, that is, spectrally smooth absorption caused by H 2 O−H 2 O pair interaction. Absorption due to the foreign continuum (i.e. caused mostly by H 2 O−N 2 bimolecular absorption in the Earth's atmosphere) was considered to be negligible in the windows. We report new retrievals of the water vapour foreign continuum from high-resolution laboratory measurements at temperatures between 350 and 430 K in four near-infrared windows between 1.1 and 5 μm (9000–2000 cm −1 ). Our results indicate that the foreign continuum in these windows has a very weak temperature dependence and is typically between one and two orders of magnitude stronger than that given in representations of the continuum currently used in many climate and weather prediction models. This indicates that absorption owing to the foreign continuum may be comparable to the self-continuum under atmospheric conditions in the investigated windows. The calculated global-average clear-sky atmospheric absorption of solar radiation is increased by approximately 0.46 W m −2 (or 0.6% of the total clear-sky absorption) by using these new measurements when compared with calculations applying the widely used MTCKD (Mlawer–Tobin–Clough–Kneizys–Davies) foreign-continuum model.

Propagation of waves with a wide range of frequencies in digital core samples and dynamic strain anomaly detection: carbonate rock as a case study

2020 ◽  
Vol 224 (1) ◽  
pp. 340-354
Author(s):  
Jun Matsushima ◽  
Mohammed Y Ali ◽  
Fateh Bouchaala
Keyword(s):  
Wave Propagation ◽  
Seismic Wave ◽  
Local Strain ◽  
Seismic Wave Propagation ◽  
Core Sample ◽  
Laboratory Measurements ◽  
Frequency Range ◽  
Broad Frequency Range ◽  
Core Samples ◽  
Digital Core

SUMMARY Recent advancements in various types of seismic measurement methods, such as sonic logging, vertical seismic profiling (VSP) and surface seismic surveys, have allowed the high-quality measurement of seismic wave propagation over a broad frequency range. To elucidate the relationship between seismic wave propagation captured by various seismic methods at widely different frequencies and in highly heterogeneous zones (e.g. fractures, vuggy zones) developed in carbonate reservoirs, laboratory measurements have been conducted over a broad frequency range. However, existing laboratory methods measure the effective properties over an entire core sample. Furthermore, there are few laboratory measurements of individual fracture stiffnesses. We propose a method to indirectly estimate the local properties caused by local anomalies (e.g. fractures) in a core sample over a broad frequency range from the dynamic elastic properties of a dry core sample using synthetic seismic waveforms generated from a digital volume of the core sample. 3-D numerical simulations were conducted over a broad frequency range using a digital core model produced by X-ray computed tomography. The proposed method was applied to numerical models and two types (fractured and vuggy) of carbonate core plugs acquired in an Abu Dhabi oil field, with the frequency ranging from 200 Hz to 100 kHz in the tests. Local strain anomalies and their frequency dependencies were successfully detected in the fractured core plug. Such frequency-dependent local responses could be associated with the micromechanics of incomplete solid–solid contacts at fractures or the heterogeneity of core samples, and thus with the frequency-dependent fracture stiffness. It was also demonstrated that the heterogeneity-induced local strain in a vuggy core plug may affect the accuracy of existing low-frequency laboratory measurements.

P-wave attenuation measurements from laboratory resonance and sonic waveform data

Geophysics ◽  
1989 ◽  
Vol 54 (1) ◽  
pp. 76-81 ◽  
Author(s):  
D. Goldberg ◽  
B. Zinszner
Keyword(s):  
Wave Attenuation ◽  
Compressional Wave ◽  
P Wave ◽  
Laboratory Measurements ◽  
Frequency Range ◽  
Waveform Data ◽  
Sonic Log ◽  
In Situ Conditions ◽  
The Mean

We computed compressional‐wave velocity [Formula: see text] and attenuation [Formula: see text] from sonic log waveforms recorded in a cored, 30 m thick, dolostone reservoir; using cores from the same reservoir, laboratory measurements of [Formula: see text] and [Formula: see text] were also obtained. We used a resonant bar technique to measure extensional and shear‐wave velocities and attenuations in the laboratory, so that the same frequency range as used in sonic logging (5–25 kHz) was studied. Having the same frequency range avoids frequency‐dependent differences between the laboratory and in‐situ measurements. Compressional‐wave attenuations at 0 MPa confining pressure, calculated on 30 samples, gave average [Formula: see text] values of 17. Experimental and geometrical errors were estimated to be about 5 percent. Measurements at elevated effective pressures up to 30 MPa on selected dolostone samples in a homogeneous interval showed mean [Formula: see text] and [Formula: see text] to be approximately equal and consistently greater than 125. At effective stress of 20 MPa and at room temperature, the mean [Formula: see text] over the dolostone interval was 87, a minimum estimate for the approximate in‐situ conditions. We computed compressional‐wave attenuation from sonic log waveforms in the 12.5–25 kHz frequency band using the slope of the spectral ratio of waveforms recorded 0.914 m and 1.524 m from the source. Average [Formula: see text] over the interval was 13.5, and the mean error between this value and the 95 percent confidence interval of the slope was 15.9 percent. The laboratory measurements of [Formula: see text] under elevated pressure conditions were more than five times greater than the mean in‐situ values. This comparison shows that additional extrinsic losses in the log‐derived measurement of [Formula: see text], such as scattering from fine layers and vugs or mode conversion to shear energy dissipating radially from the borehole, dominate the apparent attenuation.

Laboratory measurements of mass transfer of carbon dioxide and water vapour for smooth and rough flow conditions

Tellus B ◽  
1994 ◽  
Vol 46 (1) ◽  
pp. 16-32 ◽  
Author(s):  
F. J. Ocampo-Torres ◽  
M. A. Donelan ◽  
N. Merzi ◽  
F. Jia
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Water Vapour ◽  
Laboratory Measurements ◽  
Flow Conditions

scholarly journals Dynamic forces with random amplitudes from rhythmic jumps and squats

2018 ◽  
Vol 211 ◽  
pp. 09004
Author(s):  
Marek Pańtak
Keyword(s):  
Laboratory Measurements ◽  
Frequency Range ◽  
Load Models ◽  
Dynamic Forces

In the paper the load models of the dynamic forces generated during jumps and squats taking into account random changes in the amplitudes of the forces are presented. The models were elaborated on the basis of series of laboratory measurements of continuously and rhythmically performed jumps and squats in frequency range 1.40-3.80 Hz.

scholarly journals Vapour resistance of wind barrier tape: Laboratory measurements and hygrothermal performance implications

2021 ◽  
pp. 174425912110571
Author(s):  
Ida-Helene Johnsen ◽  
Erlend Andenæs ◽  
Lars Gullbrekken ◽  
Tore Kvande
Keyword(s):  
Water Vapour ◽  
Barrier Layer ◽  
Building Envelope ◽  
Climate Impacts ◽  
Adhesive Tape ◽  
Laboratory Measurements ◽  
Vapour Permeability ◽  
Wind Barrier ◽  
Increasing Demand ◽  
Drying Conditions

In the building industry, the interest into adhesive tape to achieve a more tight and robust building envelope has increased rapidly in recent years. With an increasing demand for energy efficiency in buildings, national building authorities are strengthening building requirements to mitigate and adapt to future climate impacts. This paper studies the water vapour permeability of adhesive tape for building purposes. A water vapour permeable wind barrier is essential to enable drying of the external side of the building envelope. Laboratory measurements have been conducted to evaluate how the drying conditions of the wind barrier layer are affected by the use of wind barrier tape. The results show that all the wind barrier tapes tested can be defined as significantly more vapour tight than the wind barrier itself. The wind barrier used as reference was found to have an sd-value of 0.03 m while tape ranged between 1.1 and 9.24 m. To ensure adequate drying and minimize the risk of moisture damages, the wind barrier layer should be vapour open. In an investigated construction project, the amount of tape constitutes 13% of the area of the building’s wind barrier. Further simulations need to be conducted to accurately determine the drying conditions and the following consequences.

Laboratory measurements of mass transfer of carbon dioxide and water vapour for smooth and rough flow conditions

Tellus B ◽  
1994 ◽  
Vol 46 (1) ◽  
pp. 16-32 ◽  
Author(s):  
F. J. OCAMPO-TORRES ◽  
M. A. DONELAN ◽  
N. MERZI ◽  
F. JIA
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Water Vapour ◽  
Laboratory Measurements ◽  
Flow Conditions

scholarly journals Water vapour line assignments in the 9250–26000cm−1 frequency range

2005 ◽  
Vol 233 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Roman N. Tolchenov ◽  
Olga Naumenko ◽  
Nikolai F. Zobov ◽  
Sergei V. Shirin ◽  
Oleg L. Polyansky ◽  
...  
Keyword(s):  
Water Vapour ◽  
Frequency Range
Sign in / Sign up

Export Citation Format

Share Document