Influence of frequency change during sandstone erosion by pulsed waterjet

The aims of this study were to 1) investigate gastric myoelectrical activity in patients with gastroparesis, 2) validate the cutaneous electrogastrogram (EGG) in tracking the frequency change of the gastric slow wave, and 3) investigate the effect of electrical stimulation on gastric myoelectrical activity. Gastric myoelectrical activity was recorded in 12 patients with documented gastroparesis using serosal electrodes for > 200 min in each subject. All recordings were made at least 4 days after surgery. Each session consisted of a 30-min recording in the fasting state and a 30-min recording after a test meal. The test meal (liquid or mixed) was selected according to patient's tolerance. Electrical stimulation was performed in three subjects via the serosal electrodes at a frequency of 3 cycles/min. Gastric myoelectrical activity was recorded using serosal electrodes in each session. The serosal recording showed slow waves of 2.5 to 4.0 cycles/min in all 12 subjects. Absence of spikes was noted in 11 of the 12 subjects. The simultaneous serosal and cutaneous recording of gastric myoelectrical activity showed that the frequency of the EGG was exactly the same as that of the serosal recording. Liquid meals resulted in a significant decrease in slow-wave frequency (Student's t test, P = 0.006), and the EGG accurately reflected this change. Electrical stimulation had no effect on the frequency of the gastric slow wave and did not induce spikes.(ABSTRACT TRUNCATED AT 250 WORDS)

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Magnetoelastic Coupling and Delta-E Effect in Magnetoelectric Torsion Mode Resonators

Sensors ◽

10.3390/s21062022 ◽

2021 ◽

Vol 21 (6) ◽

pp. 2022

Author(s):

Benjamin Spetzler ◽

Elizaveta V. Golubeva ◽

Ron-Marco Friedrich ◽

Sebastian Zabel ◽

Christine Kirchhof ◽

...

Keyword(s):

Low Frequency ◽

High Sensitivity ◽

Element Model ◽

Mode Number ◽

Frequency Change ◽

General Description ◽

Resonance Modes ◽

Field Sensor ◽

Magnetic Sensitivity ◽

Bending Modes

Magnetoelectric resonators have been studied for the detection of small amplitude and low frequency magnetic fields via the delta-E effect, mainly in fundamental bending or bulk resonance modes. Here, we present an experimental and theoretical investigation of magnetoelectric thin-film cantilevers that can be operated in bending modes (BMs) and torsion modes (TMs) as a magnetic field sensor. A magnetoelastic macrospin model is combined with an electromechanical finite element model and a general description of the delta-E effect of all stiffness tensor components Cij is derived. Simulations confirm quantitatively that the delta-E effect of the C66 component has the promising potential of significantly increasing the magnetic sensitivity and the maximum normalized frequency change ∆fr. However, the electrical excitation of TMs remains challenging and is found to significantly diminish the gain in sensitivity. Experiments reveal the dependency of the sensitivity and ∆fr of TMs on the mode number, which differs fundamentally from BMs and is well explained by our model. Because the contribution of C11 to the TMs increases with the mode number, the first-order TM yields the highest magnetic sensitivity. Overall, general insights are gained for the design of high-sensitivity delta-E effect sensors, as well as for frequency tunable devices based on the delta-E effect.

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A MARKOV PROCESS OF GENE FREQUENCY CHANGE IN A GEOGRAPHICALLY STRUCTURED POPULATION

Genetics ◽

10.1093/genetics/76.2.367 ◽

1974 ◽

Vol 76 (2) ◽

pp. 367-377

Author(s):

Takeo Maruyama

Keyword(s):

Genetic Variation ◽

Markov Process ◽

Diffusion Process ◽

Gene Frequency ◽

Transition Probabilities ◽

Large Population ◽

Sample Path ◽

Time Parameter ◽

Frequency Change ◽

Structured Population

ABSTRACT A Markov process (chain) of gene frequency change is derived for a geographically-structured model of a population. The population consists of colonies which are connected by migration. Selection operates in each colony independently. It is shown that there exists a stochastic clock that transforms the originally complicated process of gene frequency change to a random walk which is independent of the geographical structure of the population. The time parameter is a local random time that is dependent on the sample path. In fact, if the alleles are selectively neutral, the time parameter is exactly equal to the sum of the average local genetic variation appearing in the population, and otherwise they are approximately equal. The Kolmogorov forward and backward equations of the process are obtained. As a limit of large population size, a diffusion process is derived. The transition probabilities of the Markov chain and of the diffusion process are obtained explicitly. Certain quantities of biological interest are shown to be independent of the population structure. The quantities are the fixation probability of a mutant, the sum of the average local genetic variation and the variation summed over the generations in which the gene frequency in the whole population assumes a specified value.

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Low Power Contactless Bioimpedance Sensor for Monitoring Breathing Activity

Sensors ◽

10.3390/s21062081 ◽

2021 ◽

Vol 21 (6) ◽

pp. 2081

Author(s):

Marko Pavlin ◽

Franc Novak ◽

Gregor Papa

Keyword(s):

Dielectric Properties ◽

Low Power ◽

Medical Application ◽

Fast Response ◽

The Body ◽

Frequency Change ◽

Tissue Composition ◽

Medical Sector ◽

Bioimpedance Measurement ◽

Wide Operating

An electronic circuit for contactless detection of impedance changes in a tissue is presented. It operates on the principle of resonant frequency change of the resonator having the observed tissue as a dielectric. The operating frequency reflects the tissue dielectric properties (i.e., the tissue composition and on the tissue physiological changes). The sensor operation was tested within a medical application by measuring the breathing of a patient, which was an easy detectable physiological process. The advantage over conventional contact bioimpedance measurement methods is that no direct contact between the resonator and the body is required. Furthermore, the sensor’s wide operating range, ability to adapt to a broad range of measured materials, fast response, low power consumption, and small outline dimensions enables applications not only in the medical sector, but also in other domains. This can be extended, for example, to food industry or production maintenance, where the observed phenomena are reflected in dynamic dielectric properties of the observed object or material.

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An Improved Airborne Single Observer Passive Location

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.157-158.1533 ◽

2012 ◽

Vol 157-158 ◽

pp. 1533-1536

Author(s):

Yong Wang ◽

Chang Qiang Huang ◽

Zheng Wang ◽

Wang Xi Li

Keyword(s):

Angular Velocity ◽

Phase Difference ◽

Measurement Problem ◽

Doppler Frequency ◽

Original Method ◽

Parameter Measurement ◽

Frequency Change ◽

Passive Location ◽

Change Rate ◽

Domain Information

Using phase difference change rate’s augmentation to angular velocity, an improved passive location is developed,which solves the high precision parameter measurement problem of angular velocity in passive location and tracking via spatial-frequency domain information. The simulation shows that this method can reduce the difficulties of parameter measurement. The ranging error is mainly affected by the measurement error of phase difference change rate and doppler frequency change rate. Compared with the original method, it has higher passive location precision.

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Synchronization in Dual Delay Line SAW Sensors

Design Engineering ◽

10.1115/imece2004-59979 ◽

2004 ◽

Author(s):

Duck-Bong Seo ◽

Z. C. Feng

Keyword(s):

Delay Line ◽

Phase Measurement ◽

Surface Adsorption ◽

Propagation Speed ◽

Frequency Measurement ◽

Frequency Change ◽

Averaged Equations ◽

Excited Oscillation ◽

The Difference ◽

Delay Differential

Surface acoustic wave (SAW) sensors are self-excited oscillators. Self-excitation is a consequence of the finite amount of delay in the circuit. The oscillation frequency is affected by the wave propagation speed which further depends on surface adsorption. Therefore, measurement on the surface adsorption is done by measuring the frequency change of the self-excited oscillation. In dual delay line oscillators the difference between the surface physical conditions is reflected through the difference in oscillation frequencies. Delay differential equations are used to model the sensor. Bifurcation analysis of the averaged equations indicates the presence of synchronization. The occurrence of synchronization is further demonstrated through numerical simulations. Synchronization makes the frequency measurement irrelevant. We propose phase measurement as an alternative in the presence of strong coupling between the two oscillators.

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Stimulated electromagnetic shock radiation (SESR) in frequency-dispersive media

Canadian Journal of Physics ◽

10.1139/p77-190 ◽

1977 ◽

Vol 55 (17) ◽

pp. 1499-1509 ◽

Cited By ~ 5

Author(s):

S. Schneider ◽

R. Spitzer

Keyword(s):

Resonance Frequency ◽

Energy Levels ◽

Stimulated Emission ◽

Dispersive Media ◽

Electron Trajectory ◽

Frequency Change ◽

Electromagnetic Shock ◽

Frequency Changes ◽

Shock Frequency ◽

Shock Fronts

The interaction in a frequency-dispersive medium of a coherent electromagnetic wave with an electron moving faster than a critical (Mach) speed produces electromagnetic radiation with novel characteristics. Theory predicts emission of intense radiation in the form of shock fronts at specific angles from the electron trajectory. The shock fronts are correlated with specific frequencies shifted significantly from that of the incident wave. We have named this effect stimulated electromagnetic shock radiation (SESR). The shock frequencies depend dynamically on the populations of the energy levels that give rise to the medium resonances. A given shock frequency changes from below to above the resonance frequency of the medium with which it is associated as the populations of the two energy levels corresponding to this resonance frequency change from an equilibrium distribution to an inverted one. This dynamic resonance crossing points to the possibility of new synergisms between SESR emission and stimulated emission between discrete levels.

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Development of QCM Biosensor with Specific Cow Milk Protein Antibody for Candidate Milk Adulteration Detection

Journal of Sensors ◽

10.1155/2016/1807647 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7 ◽

Cited By ~ 11

Author(s):

Setyawan P. Sakti ◽

Nur Chabibah ◽

Senja P. Ayu ◽

Masdiana C. Padaga ◽

Aulanni’am Aulanni’am

Keyword(s):

Milk Protein ◽

Protein A ◽

Goat Milk ◽

Specific Protein ◽

Cow Milk ◽

Frequency Change ◽

Milk Product ◽

Reaction Cell ◽

Buffer Solution ◽

Milk Adulteration

Adulteration of goat milk is usually done using cow’s milk product. Cow milk is used as it is widely available and its price is cheaper compared to goat milk. This paper shows a development of candidate tools for milk adulteration using cow milk. A quartz crystal microbalance immunosensor was developed using commercial crystal resonator and polyclonal antibody specific to cow milk protein. A specific protein at 208 KDa is found only in cow milk and does not exist in goat milk. The existence of this protein can be used as an indicator of cow milk content in a target solution. To detect the PSS 208 kDa protein, antibody specific to the PSS 208 was developed. The purified antibody was immobilized on top of the sensor surface on a polystyrene layer. The fraction of the immobilized antibody on the sensor was found at 1.5% of the given antibody. Using a static reaction cell, the developed immunosensor could detect the specific cow milk protein in buffer solution. The detection limit is 1 ppm. A linear relationship between frequency change and specific protein of cow milk concentration is found from a concentration of 1 ppm to 120 ppm.

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