Papers by Keyword: Ultrasonic

Abstract: The spectrum analysis system, which is based on TMS320F2808, can detect ultrasonic signal in real time. The signal is transformed from time domain to frequency domain by use of FFT. The spectrum graph can be displayed on LCD in real time. The practical results illustrated that this system can analyze the frequency spectrum efficiently with the range of 30kHz~50kHz.

Abstract: This research aims at investigating the response characteristics of fiber Bragg grating sensors (FBGs) to ultrasonic signals. The testing system was set up with a tunable laser source and the FBGs installed on the surface of an aluminum plate. Then the response characteristics of FBGs were compared, in condition of putting the ultrasonic driving source in the different longitudinal, lateral and angular separation. Measurements were taken by changing the distance between the sensor and the transducer from 60 mm to 200 mm with a step of 20 mm. Then keeping the distance at 100 mm and 200 mm respectively, do the angular experiment with the angle from 0° to 90° by the step of 10°. Experiment results show that FBG can get better signals when the transducer is along its axial direction. When the location of the transducer is changed linearly, no obvious linear change of the signal strength has been found.

Abstract: The self-aggregation of polysaccharides (PS) in solution has led to high viscosity, unstable biological activity and poor resolution in instrumental characterization as well. In this work, ultrasound with low power level was applied to disrupt the PS aggregation of an exopolysaccharide(EPS) from Cordyceps sinensis mycelial culture. Ultrasonic irradiation with 20% amplitude (about 4 W) for 0.5 min decreased the specific viscosity of EPS by 59%. Dynamic light scattering(DLS) experiments on native EPS showed four distinct population with diameter range of 10~500 nm, 500~2500 nm, 3500~12300 nm and 22150~115400 nm respectively. The peaks at large size range in the intensity-weighted size distribution disappeared or shifted to small size range, indicating a gradual disassociation of EPS with the prolongation of ultrasonic duration. AFM observation proved the disassociation of EPS from a highly across-linked gel into single strand under ultrasonic treatment. According to DLS analysis, ultrasonic treated EPS did not show any sign of aggregation over 8 days in contrast to an immediate aggregation growth with native EPS. Ultrasonic irradiation control PS association by means of weakening the hydrogen bonds through the hydrodynamic shear forces arising from acoustic cavitation in the irradiated liquid, which has importance in the applications and structural characterization of PS.

Abstract: In order to achieve real-time interactive movement control of three-dimensional solid model, using ultrasound features to achieve its function; established real-time interactive motion control models of three-dimensional solid model, and through the circuit design, it achieved transmit and receive of ultrasonic, so that it achieves real-time interactive movement control of three-dimensional solid model.

Abstract: The quality of ultrasonic flaw echo signal is the foundation of achieving qualitative and quantitative analysis in the in ultrasonic flaw detection. In practice, the flaw echo signals are often contaminated or even annihilation by random noise. According to the characteristics of ultrasonic flaw echo signal, wavelet packet has more accurate local analysis ability in low frequency and high frequency part. This paper discusses de-noising in ultrasonic signals based on wavelet packet analysis, and proposes an improved threshold approach for de-noising. The results show that: It remarkably raises the signal-to-noise ratio of ultrasonic flaw echo signal and improves the quality of signal with improved wavelet packet threshold.

Abstract: Both water decoction method and ultrasonic-assisted method were used to compare the extraction efficiency during the extraction of flavonoids from honeysuckle leaves. Three dynamic models were adopted in study of the extraction dynamics. The results show that the ultrasonic wave strengthening can improve the extraction efficiency of flavonoids comparing water decoction method in the experimental conditions. The ultrasonic wave strengthening extraction dynamic equation agrees with , while the water decoction method extraction dynamic equation agrees with .

Abstract: Automobile reversing process should be paying more attention for security. This paper analyzes the principle of ultrasonic distance measurement, made simple and practical automobile reversing radar, in which the SPCE061A MCU / DSP of high-performance 16-bit microprocessor was used as the control core and the ultrasonic sensors modular for detection signal. The system design is the modularization structure, so as to simplify the debugging effort, well done eventually reversing radar. The experiments shows that the detection range may be up to 15cm-200cm, the error of distance is only 5cm, fully meet the practical requirements, and low cost.

Abstract: A new method, triboelectricity and ultrasonic, for the soot mass flow measurement is developed. The direct rod-shaped sensor is used to measuring the triboelectricity charge and the ring sensor is used to measuring the electrostatic induction charge. The pure-triboelectricity can be figured out and the pure-triboelectricity is eliminated the influence of the electrostatic induction. Through the numerical simulation, the proportion between the electrostatic induction charge and the electrostatic induction charge is presented. The gas flowrate is measured by the ultrasonic. The soot mass flow can be figured out through the pure-triboelectricity and the gas velocity. Additionally, the sample calibration equipment based on the pure-triboelectricity and ultrasonic method is also introduced. Experimental results show the method can on-line measure the soot mass flow.

Abstract: The mechanism of ultrasonic ranging has the advantages of being simple in structure, low cost, high measurement speed, and free from the environmental constrain, such as severe whether. It has been widely adopted even through there are still some shortcomings in the measurement range, such as the measurement interval limitation, wave beam over wide , poor resolution in direction, and unexpected reflection phenomenon in mirror[1-3].The main principle of ultrasonic ranging is to measure transit time that ultrasonic emits through launched probe, more specific, is the total travel time of the ultrasonic wave from the probe passing the target, reflected by the target , and then coming back to the received probe in the same route. The distance between sensor and the target is calculated by the half value of the arithmetic product between the transit time and the speed of propagation of the ultrasonic wave in the medium. The measurement for the transit time includes: Pulse-echo method, Phase difference method, and Frequency difference method [4-6]. Among the methods, the accuracy of the Pulse-echo method is always related to the size of the echo signal amplitude, which is influenced easily by environmental elements. However, it has the advantages of simple measurement circuit, easy implementation, and low cost, which leads to its wide application. Considering the problems of cross interference and aliasing effect, as well as the occasional false triggering phenomenon in the occasions of multiple ultrasonic ranging, this study designed a special ultrasonic ranging finder to avoid them by employing the technology of codec. The experimental conclusion shows that it can be reliably applied to the occasions that multiple ultrasonic range finders are adopted used at the same time.

Abstract: With the ultrasound was put into the experiment of cast-rolling lead alloy strip, it broke the dendrite structures and enhanced the under-cooling by the effect of cavity and acoustic streaming. The microstructure comparison of ultrasound and general cast-rolling shows that: The grain size of general cast-rolled lead strip is big; the grain boundary is coarse and the organization structure is uneven. However, the grain structure is refined, smaller grains and uniform organization structure is acquired with ultrasound treatment. Besides, the mechanical properties test results of the two kinds lead alloys shows that the ultrasound cast-rolling lead alloys are better than general cast-rolling. The tensile strength, yield strength and elongation of ultrasound cast-rolling lead strip are increased by 11.30%, 22.15% and 21.74% than that of general cast-rolling lead strip.