Search results for "ACOUSTIC"
showing 10 items of 1590 documents
PREDICTION OF INSTRUMENTAL AND SENSORY TEXTURAL CHARACTERISTICS OF MAHON CHEESE FROM ULTRASONIC MEASUREMENTS
2000
Ultrasonic velocity was related to sensory and instrumental texture measurements. A semi-logarithmic model (Weber-Fechner) was used to relate the sensory and instrumental texture measurements. The ultrasonic velocity ranged from 1650 to 1723 m/s for the softest and hardest cheese, respectively. As expected from theoretical equations, the ultrasonic velocity was related to the square root of the instrumental measurements. The deformability modulus (r 2 =0.93) and the slope in puncture (r 2 =0.85) were the most closely related parameters. A model developed from the relationship between sensory and instrumental texture and the relationship between ultrasonic velocity and instrumental texture, …
Simple New Method for the Preparation of La(IO3)3 Nanoparticles
2020
We present a cost- and time-efficient method for the controlled preparation of single phase La(IO3)3 nanoparticles via a simple soft-chemical route, which takes a matter of hours, thereby providing an alternative to the common hydrothermal method, which takes days. Nanoparticles of pure &alpha
Microstructure-oxidation resistance relationship in Ti3AlC2 MAX phase
2020
International audience; Spark Plasma Sintering and Hot Isostatic Pressing were used to synthesize coarse-grained and fine-grained Ti3AlC2 specimens. Moreover, Spark Plasma Sintering processing parameters were modified in order to vary the TiC, Al2O3 and TixAly impurity and the porosity contents in the fine-grained samples. The influence of the Ti3AlC2 microstructure on the oxidation resistance was assesed. It is demonstrated that the grain size can drastically modify the oxidation resistance. The higher density of grain boundaries, in fine-grained specimens, increases the number of Al diffusion paths and leads to the formation of a protective alumina scale. In coarse-grained sample, Al diff…
Regenerable ZnO/GaAs Bulk Acoustic Wave Biosensor for Detection of Escherichia coli in “Complex” Biological Medium
2021
A regenerable bulk acoustic wave (BAW) biosensor is developed for the rapid, label-free and selective detection of Escherichia coli in liquid media. The geometry of the biosensor consists of a GaAs membrane coated with a thin film of piezoelectric ZnO on its top surface. A pair of electrodes deposited on the ZnO film allows the generation of BAWs by lateral field excitation. The back surface of the membrane is functionalized with alkanethiol self-assembled monolayers and antibodies against E. coli. The antibody immobilization was investigated as a function of the concentration of antibody suspensions, their pH and incubation time, designed to optimize the immunocapture of bacteria. The perf…
Analysis of the effects of pulsed microwave on cardiac activity
1993
Abstract The exposure of isolated chick embryo hearts to 2.45 GHz pulse modulated microwaves has identified certain phenomena: (1) when the heartbeat was irregular, an appropriate pulse repetition rate caused regularization; (2) during regular beating, an increase of pulse repetition rate similarly increased the heartbeat frequency, until an irregular heartbeat appeared; (3) by applying microwaves, when an arrhythmia occurs, a regular beat appeared after a few seconds. Time correlation between the heartbeat and the modulating pulses revealed that regularization occurs when the modulation pulses, at a frequency close to the natural unperturbed heartbeat, were applied in the ventricular diast…
All-fiber lasers actively modelocked by acousto-optic modulation
2010
The development of all-fiber lasers is of high interest because of the intrinsic robustness, compactness and energy efficiency. In-fiber amplitude modulators based on acousto-optic modulation of fiber Bragg gratings (FBG) permit the implementation of novel all-fiber actively modelocked lasers. Using either traveling or standing longitudinal acoustic waves, optical pulses between 500 and 100 mW peak powers and ∼ 700 ps temporal width were obtained at 4.1 and 9 MHz repetition rates, respectively. Implementing a simultaneous active Q-switching, we have demonstrated a doubly active Q-switching and mode-locking of two different all-fiber laser configurations. In the case of the laser based on tr…
Non-contact ultrasonic inspection of skin/core bond in honeycomb with lamb waves
2003
The assessment of skin/core bond in honeycomb samples was carried out by a bistatic ultrasonic non-contact system. Lamb waves were generated by a Nd:YAG pulsed laser and detected by an air-coupled capacitance transducer located in pitch-catch configuration. Periodically spaced line sources, generated on the sample surface using a four element lenticular array, allowed generation of narrow-band directional Lamb waves. Changes in amplitude of the transmitted signal permitted detection of skin/core disbonds.
Deformation-Free Topography from Combined Scanning Force and Tunnelling Experiments
1993
We show that by measuring force and stiffness on a constant-current scanning tunnelling microscopy (STM) contour a deformation-free topography can be extracted. With reference to mono- and bicomponent self-assembled monolayers, we find that the characteristic depression pattern and the protrusions on a multicomponent film found in STM are to a great extent due to electronic effects.
Optical thermal filters for eXTP: manufacturing and characterization
2020
In order to ensure the effective detection of X-ray astronomical detectors by blocking ultraviolet, visible and infrared light, adding optical thermal filter in front of the load is an effective method. According to the scientific requirements of eXTP, optical thermal filters with aluminized polyimide (PI) film structure had been designed and tested in this paper, the results of mechanical tests including burst pressure, vibration and acoustic tests, also the transparent properties of optics in UV, Vis and IR lights are presented. The mechanical test results show that the filters for LAD and SFA can't pass the acoustic tests, causing the thickness of PI should be increased or a nickel mesh …
Acoustic vibrations of embedded spherical nanoparticles
2005
Abstract A solid-matrix-embedded spherical nanoparticle has acoustic vibrational frequencies which are shifted and damped relative to modes of a free sphere. Not only the longitudinal plane wave acoustic impedances, but also the Poisson ratios of nanoparticle and matrix are important in determining the Q-factor of the “breathing” mode, for which frequencies and Q-factors with different material combinations are presented. High matrix sound speed (e.g. silica, titania, alumina, diamond) increases Q.