Mechanical Response of the Lungs at High Frequencies

1978 ◽  
Vol 100 (2) ◽  
pp. 57-66 ◽  
Author(s):  
J. J. Fredberg ◽  
A. Hoenig
Keyword(s):  
Efficient Method ◽  
High Frequency ◽  
Input Impedance ◽  
Mechanical Response ◽  
Airway Wall ◽  
Frequency Range ◽  
Resonant Frequencies ◽  
High Frequencies ◽  
Branching Networks ◽  
Adult Humans

We put forward an efficient method for computing the input impedance of complex asymmetrically branching duct networks, and apply this method to simulation of the dynamic response of the lungs of normal adult humans in the frequency range extending to 10,000 Hz. The results indicate that the response of comparable symmetric and asymmetric branching networks differ at high frequency (> 2 kHz in air), and that the airway wall response is an important factor in determining system damping and resonant frequencies.

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.

High Frequency Length Mode PVDF Behavior over Temperature

2008 ◽  
Vol 1134 ◽  
Author(s):  
Mitch Thompson ◽  
Minoru Toda ◽  
Melina Ciccarone
Keyword(s):  
High Frequency ◽  
Elastic Behavior ◽  
Temperature Dependent ◽  
Metal Electrodes ◽  
Resonant Frequencies ◽  
High Frequencies ◽  
Silver Ink ◽  
Angle Data ◽  
Thermal Chamber ◽  
Impedance Testing

AbstractIn an extension of earlier work, the temperature dependent parameters of PVDF operating in the length mode have been measured at frequencies useful in air ultrasound (20kHz to 100kHz) over a -45°C to +65°C temperature range. The length mode resonance of PVDF strips of different lengths was excited by mechanically clamping samples at the mid point during dielectric impedance testing conducted in a desiccated thermal chamber. Material properties were extracted from the impedance magnitude and phase angle data at temperature, and the various sample lengths allowed a range of resonant frequencies to be studied. Overall results generally confirm the visco-elastic behavior of PVDF. Testing was conducted on samples with both thin sputtered metal electrodes (∼60nm) and thicker elastomeric silver ink electrodes (∼8μm) to assess the performance difference. Silver ink is preferred in production as sputtered metal has current density an other limitations, but it causes a serious loss in performance at high frequencies.

Extended High-Frequency Thresholds in Older Adults

1997 ◽  
Vol 40 (1) ◽  
pp. 208-214 ◽  
Author(s):  
Lois J. Matthews ◽  
Fu-Shing Lee ◽  
John H. Mills ◽  
Judy R. Dubno
Keyword(s):  
High Frequency ◽  
Age Groups ◽  
Test Session ◽  
Normal Hearing ◽  
Gender Effects ◽  
Frequency Range ◽  
Age And Gender ◽  
High Frequencies ◽  
And Gender ◽  
Test Retest Reliability

Most measures of auditory sensitivity at extended high frequencies (frequencies greater than 8 kHz) have been obtained from listeners with normal hearing less than 40 years of age. The purpose of this study was (a) to measure thresholds at frequencies above 8 kHz in older listeners who, as a group, have elevated thresholds at lower frequencies, and (b) to assess test-retest reliability, age and gender effects, and the influence of thresholds below 8 kHz. Extended high-frequency (EHF) thresholds were measured for 162 older listeners (60–79 years) using a commercially available high-frequency audiometer, with a frequency range of 8 to 18 kHz and an intensity range of 0 to 110 dB SPL. Thresholds were measured once at the beginning of a 1- to 2-hour test session and then remeasured at the end of the test session. EHF thresholds of older listeners with normal hearing at conventional audiometric frequencies were substantially higher than the thresholds reported for younger listeners with normal hearing by Dreschler and van der Hulst (1987). EHF thresholds of older listeners with hearing loss at conventional audiometric frequencies were further elevated as compared to older listeners with normal hearing. Differences in EHF thresholds between females and males were either not present or were reduced when gender differences in conventional audiometric thresholds were taken into account. No significant differences were seen in thresholds at 8 kHz and higher between the 60- to 69- and 70- to 79-year-old age groups. Results also indicated that thresholds above 8 kHz can be measured in older listeners within a clinically acceptable ±10 dB test-retest range.

Inorganic-Organic Hybrid Polymers as Photo-Patternable Dielectrics for Multilayer Microwave Circuits

2002 ◽  
Vol 726 ◽  
Author(s):  
L. Fröhlich ◽  
R. Houbertz ◽  
S. Jacob ◽  
M. Popall ◽  
R. Mueller-Fiedler ◽  
...  
Keyword(s):  
Material Properties ◽  
High Frequency ◽  
Low Cost ◽  
Microwave Circuits ◽  
Cross Linking ◽  
Frequency Range ◽  
Hybrid Polymers ◽  
High Frequencies ◽  
Film Coatings ◽  
Organic Hybrid

AbstractInorganic-organic hybrid polymers (ORMOCE®s) combine very good optical and dielectricproperties in the frequency range up to 1 MHz (εr = 3.1 and tanδ = 0.004, both at 1 MHz). Thisis particularly promising for electro-optical (e/o) applications. Multi-layer microwave circuits forhigh frequency applications up to 100 GHz demand extraordinary material properties such as alow permittivity εr < 3 and a dielectric loss tanδ of about 10-3. For low-cost processing, direct UVpatterning would be particularly advantageous. Additionally, the material should be thermallystable at least up to temperatures around 300°C.We have developed a series of novel ORMOCE® materials for high frequency applications.Using these ORMOCE®s, thick film coatings (up to 150 m) can be produced and directlypatterned by UV lithography with sufficiently high resolution. The synthesis has been carried outusing styrene-substituted organosilanes and silanediols as precursors reacted by simplified solgel-processing in combination with organic cross-linking of polymerizable organic functions.The materials have been characterized at high frequencies up to 40 GHz, exhibiting verypromising dielectric properties of εr = 2.5 and tanδ = 0.0035.

Numerical Mode Matching Approach for Acoustic Attenuation Predictions of Double-Chamber Perforated Tube Dissipative Silencers with Mean Flow

2014 ◽  
Vol 22 (02) ◽  
pp. 1450004 ◽  
Author(s):  
Z. Fang ◽  
Z. L. Ji
Keyword(s):  
High Frequency ◽  
Present Method ◽  
Transmission Loss ◽  
Mode Matching ◽  
Acoustic Behavior ◽  
Frequency Range ◽  
Mean Flow ◽  
High Frequencies ◽  
Perforated Tube ◽  
Double Chamber

The transfer matrix method (TMM) based on numerical mode matching (NMM) approach is developed to investigate the acoustic behavior of double-chamber perforated tube dissipative silencer with mean flow. The present method is verified by comparing the transmission loss (TL) predictions and experimental data. Then the effects of mean flow, perforated tube offset and lengths of perforations are studied computationally. As the Mach number increases, the TL of dissipative silencer is lowered at most frequencies. The perforated tube offset may change the acoustic behavior in the mid-high frequency range. Increasing the total length of perforations increases TL at the mid-high frequencies.

scholarly journals A Simple and Efficient Method for Designing Broadband Terahertz Absorber Based on Singular Graphene Metasurface

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1351 ◽  
Author(s):  
Zhongmin Liu ◽  
Liang Guo ◽  
Qingmao Zhang
Keyword(s):  
Numerical Simulation ◽  
Efficient Method ◽  
Input Impedance ◽  
Wide Frequency Range ◽  
Circuit Model ◽  
Frequency Range ◽  
Terahertz Absorber ◽  
Relative Bandwidth ◽  
Analytical Expressions ◽  
Broadband Terahertz

In this paper, we propose a simple and efficient method for designing a broadband terahertz (THz) absorber based on singular graphene patches metasurface and metal-backed dielectric layer. An accurate circuit model of graphene patches is used for obtaining analytical expressions for the input impedance of the proposed absorber. The input impedance is designed to be closely matched to the free space in a wide frequency range. Numerical simulation and analytical circuit model results consistently show that graphene metasurface-based THz absorber with an absorption value above 90% in a relative bandwidth of 100% has been achieved.

Stroke volume effect of changing arterial input impedance over selected frequency ranges

1985 ◽  
Vol 248 (4) ◽  
pp. H477-H484 ◽  
Author(s):  
K. Sunagawa ◽  
W. L. Maughan ◽  
K. Sagawa
Keyword(s):  
Stroke Volume ◽  
High Frequency ◽  
Input Impedance ◽  
Characteristic Impedance ◽  
Low Frequency ◽  
Volume Effect ◽  
High Frequency Range ◽  
Frequency Range ◽  
Windkessel Model ◽  
End Diastolic Volume

We investigated the effect of changing arterial input impedance over three selected frequency ranges on stroke volume (SV) in nine isolated canine left ventricles. The input impedance was simulated with a three-element Windkessel model (i.e., resistance, characteristic impedance, and compliance) and was imposed on the ventricles with a servo-controlled loading system. Under a constant end-diastolic volume [33.1 +/- 1.5 (SE) ml], we changed the modulus of the afterloaded impedance over a low frequency range (below 0.13 Hz) by changing the resistance, over a transitional frequency range (in which the impedance modulus decreases from total resistance to characteristic impedance) by changing the compliance, and over a high frequency range (above 2.0 Hz) by changing the characteristic impedance. Each of the impedance components was changed from control to 50 and 200% of control. SV sensitively decreased from 16.1 +/- 0.7 to 7.4 +/- 0.5 ml in response to the increase in the low-frequency impedance modulus. SV was relatively insensitive, however, to the same percent increase in the impedance modulus over the transitional frequency range (from 11.2 +/- 0.6 to 12.3 +/- 0.7 ml) and over the high frequency range (from 11.9 +/- 0.6 to 11.6 +/- 0.7 ml). The average relative sensitivities of SV to the increase and decrease in impedance moduli in these frequency ranges were 1.2:0.12:0.04. We conclude that the modulus of impedance in the low frequency range is, by far, a more important determinant of SV than those in the transitional and high frequency ranges.

scholarly journals Low-frequency sampling rates are effective to record bottlenose dolphins

2021 ◽  
Vol 8 (7) ◽  
pp. 201598
Author(s):  
Bianca Romeu ◽  
Alexandre M. S. Machado ◽  
Fábio G. Daura-Jorge ◽  
Marta J. Cremer ◽  
Ana Kássia de Moraes Alves ◽  
...  
Keyword(s):  
High Frequency ◽  
Bottlenose Dolphins ◽  
Sampling Rate ◽  
Low Frequency ◽  
Frequency Range ◽  
High Frequencies ◽  
Limited Sampling ◽  
High Sampling Rate ◽  
Frequency Sampling ◽  
Lower Frequencies

Acoustic monitoring in cetacean studies is an effective but expensive approach. This is partly because of the high sampling rate required by acoustic devices when recording high-frequency echolocation clicks. However, the proportion of echolocation clicks recorded at different frequencies is unknown for many species, including bottlenose dolphins. Here, we investigated the echolocation clicks of two subspecies of bottlenose dolphins in the western South Atlantic Ocean. The possibility of recording echolocation clicks at 24 and 48 kHz was assessed by two approaches. First, we considered the clicks in the frequency range up to 96 kHz. We found a loss of 0.95–13.90% of echolocation clicks in the frequency range below 24 kHz, and 0.01–0.42% below 48 kHz, to each subspecies. Then, we evaluated these recordings downsampled at 48 and 96 kHz and confirmed that echolocation clicks are recorded at these lower frequencies, with some loss. Therefore, despite reaching high frequencies, the clicks can also be recorded at lower frequencies because echolocation clicks from bottlenose dolphins are broadband. We concluded that ecological studies based on the presence–absence data are still effective for bottlenose dolphins when acoustic devices with a limited sampling rate are used.

The Frequency Response of Pneumatic Lines

1967 ◽  
Vol 89 (2) ◽  
pp. 371-378 ◽  
Author(s):  
J. T. Karam ◽  
M. E. Franke
Keyword(s):  
Frequency Response ◽  
High Frequency ◽  
Signal Frequency ◽  
Frequency Range ◽  
Frequency Model ◽  
Resonant Frequencies ◽  
Frequency Dependent ◽  
Amplitude Frequency Response ◽  
Theoretical Predictions ◽  
Response Transfer

The amplitude frequency response (transfer gain curve) of 0.170-in-ID blocked pneumatic lines of the type used in fluidic systems was experimentally determined. Several lengths (20 ft and less) of tubing at several mean pressures (10 to 40 psig) were studied over the frequency range of 1-1000 cps. The electric-pneumatic analogy was used to develop theoretical predictions of the gain curves. Correlation with experiment showed that a frequency-dependent resistance and a frequency-dependent conductance were required in the analogy when the signal frequency was somewhat greater than a characteristic frequency of the line. A high-frequency model, based on the work of Nichols, was developed; it predicted the resonant gains within 2 db and the resonant frequencies within 10 percent.

Experimental investigation of damage detection in plate-like structure using combined energetic approaches

2018 ◽  
Vol 233 (4) ◽  
pp. 1193-1203
Author(s):  
Ahmed Samet ◽  
Yi Hui ◽  
Mohamed Amine Ben Souf ◽  
Olivier Bareille ◽  
Mohamed Ichchou ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Damage Detection ◽  
Energy Method ◽  
High Frequency ◽  
Excitation Source ◽  
High Frequency Range ◽  
Frequency Range ◽  
High Frequencies ◽  
Frequency Bands ◽  
Different Characteristics

In this paper, an experimental investigation of damage detection in plate-like structure using energetics approaches is presented. Two energetics approaches are developed to localize the damage in structure at low-, medium-, and high-frequency range. The first one is the inverse simplified energy method, which is used for the identification of the excitation source and the detection of damage in medium and high frequencies. The second one is the curvature method, which is used for the damage detection in the low and medium frequencies. The main novelty of this paper is to combine these energetics approaches in order to localize the damage in all frequency bands. Experimental examples with different characteristics of plate were performed for the validation purpose. Results show that the presented methods can detect precisely the defects location in plate-like structures.

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