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Contact angle is one of the important parameters in judging the level of wetting ability of liquid to solid.A method called droplet image analyzing which used Matlab is introduced in this paper.Firstly,original images are acquired with... more
Contact angle is one of the important parameters in judging the level of wetting ability of liquid to solid.A method called droplet image analyzing which used Matlab is introduced in this paper.Firstly,original images are acquired with CCD camera and pre-processed by image enhancement,image de-noising and image sharpening technologies.Secondly,the Canny optimization operator is applied to extract the droplet's contour.Finally,the contact angle was acquired by curve fitting.A novel method was provided for measurements of contact angle.
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Characteristics of droplet particle size distribution(PSD)in concentrated fat emulsions were investigated using ultrasonic attenuation measurement.Based on theoretical analysis and numerical results,the experiments in ultrasonic spectrum... more
Characteristics of droplet particle size distribution(PSD)in concentrated fat emulsions were investigated using ultrasonic attenuation measurement.Based on theoretical analysis and numerical results,the experiments in ultrasonic spectrum with a bandwidth range of 2～13 MHz measurement were carried out for oil volume fraction from 1%to 20%.Combined with the inverse algorithm,fat droplet sizes and distributions were determined from experimental data.Comparison with the results of light extinction method indicated that ultrasonic spectra method could produce fairly consistent PSD results,in which particle sizes were below 1μm.The error of experimental volume fraction and initial fraction(20%)is 3%and the deviation error between retrieval spectrum and experimental spectrum is smaller than 10%.Moreover,it is suitable for high concentration emulsion and non-destructive tests.
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A new ultrasonic propagation theory for particulate two-phase flow,the so-called ultrasonic multi-signal combination method,was presented.The acoustic impendence,velocity and attenuation in dense particulate two-phase flow were determined... more
A new ultrasonic propagation theory for particulate two-phase flow,the so-called ultrasonic multi-signal combination method,was presented.The acoustic impendence,velocity and attenuation in dense particulate two-phase flow were determined by single and multiple echo reflection signals.Through these enough acoustic informations,the density,concentration and particle size of particulate two-phase flow were obtained.The application based on this theory is also suitable to measure concentration,density and particle size of dense particulate two-phase flow.The experimental results of coal-water slurry show that the measured density,concentration and particle size conincide with the known and standard results.
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Particles exist in many areas,their characterization measurement and monitoring are of great importance.With the development of technology,digital image processing technique as a direct-viewing and non-contact measurement method has been... more
Particles exist in many areas,their characterization measurement and monitoring are of great importance.With the development of technology,digital image processing technique as a direct-viewing and non-contact measurement method has been widely used.However,in the optical imaging system,the depth of field is limited.In order to increase the measurement range,the defocus images should be processed.Defocus image of spherical particles were studied from simulation and experiment.It was proven that the gradient of image transition area and the defocus distance were related,and the difference of two maximum gradients along the radial direction was the particle diameter in image.
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A prospective diagnosis method for coronary heart disease (CHD) using human urine based on surface-enhanced Raman spectroscopy (SERS) is proposed, and could provide valuable information for judging whether to perform percutaneous coronary... more
A prospective diagnosis method for coronary heart disease (CHD) using human urine based on surface-enhanced Raman spectroscopy (SERS) is proposed, and could provide valuable information for judging whether to perform percutaneous coronary intervention (PCI) in clinics. Here, urine samples from 87 patients with CHD, including patients with PCI before operation (degree of cardiovascular congestion above 70%) and without PCI (degree of cardiovascular congestion under 70%), and 20 healthy humans were measured using SERS. Principal component analysis (PCA) combined with linear discriminant analysis (LDA) was employed to analyze the SERS spectra, revealing that the classification sensitivity and specificity were 90% and 78.9%, respectively, and the absolute value for loading of PC1 at 1509 cm-1 was the largest. Since platelet-derived growth factor-BB (PDGF-BB) is closely related to CHD, PDGF-BB aqueous solutions with various concentrations (1, 0.5, 0.1, 0.05 and 0.01 ppm) and a mixture of...
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The moving single-frame and long-exposure (M-SFLE) imaging method was used to carry out two-dimensional experimental researches to study the vortices merging in the turbulent boundary layer of a rectangular channel. Through experiments,... more
The moving single-frame and long-exposure (M-SFLE) imaging method was used to carry out two-dimensional experimental researches to study the vortices merging in the turbulent boundary layer of a rectangular channel. Through experiments, the change of the vortex structures over a period of time can be obtained, due to the measurement system moves at a constant speed that similar to the moving velocity of the vortices. And the continuous long exposure measurement method could record the trajectory of the tracer particles to visualize the structure of vortices. An image processing algorithm based on skeleton extraction was used to obtain the velocity information of the flow field, and Liutex is used to quantitatively analyze the vortices merging phenomenon. The experimental research shows that the MSFLE method is an effective and convenient flow field visualization measurement method, which can visualize the development and change of the vortex structures over a period of time. Liutex ...
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Conventional dynamic light scattering (DLS) using a CCD camera as optical area detector (here we called Image Dynamic Light Scattering method, for the data acquired by images ) has been developed successfully. We present a model... more
Conventional dynamic light scattering (DLS) using a CCD camera as optical area detector (here we called Image Dynamic Light Scattering method, for the data acquired by images ) has been developed successfully. We present a model experiment in a micro-channel to study flowing Brownian motion systems of polystyrene latex particles by using Image Dynamic Light Scattering method (IDLS). The modified correlation function proposed by Chowdhury et al , which is applied to the analysis of extracting the size and velocity of laminar flowing particulate dispersions, is used in the paper to obtain the particle size from the scattered light signals. The new method allows for much shorter measurement time compared to conventional DLS. As the inversion algorithm of polydisperse system is yet very complex, the measurement of the paper is for monodisperse polystyrene latex particles. © 2014 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of Chinese Society of ...
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The concentration and size distribution of particles in two‐phase flow play an important role in a wide variety of industrial areas, while their measurement still remains troublesome at the present day. Ultrasonic wave as a mechanical... more
The concentration and size distribution of particles in two‐phase flow play an important role in a wide variety of industrial areas, while their measurement still remains troublesome at the present day. Ultrasonic wave as a mechanical vibration contains plenty of information about medium which it passes through. Thus the particle concentration and size distribution could be extracted from measured ultrasonic velocity by means of well‐established models and data processing techniques. In this paper, coal‐water slurries and fat emulsions were studied with an experiment apparatus which implements a twice pulse‐echo measurement simultaneously. Ultrasonic velocity was obtained by recording the time‐of‐flight (TOF) of a known fixed sound‐path length and the fitness of experimental data was carried out to yield the concentration of slurries. The frequency dispersion phenomenon of sound in the fat emulsions was observed and the frequency‐dependent phase velocity was worked out through an insert substitution metho...
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Abstract A meshless radial basis function (RBF) method combined with the modified Tikhonov regularization is proposed to reconstruct the two-dimensional velocity field. Time-of-flight data is obtained to capture the flow information of... more
Abstract A meshless radial basis function (RBF) method combined with the modified Tikhonov regularization is proposed to reconstruct the two-dimensional velocity field. Time-of-flight data is obtained to capture the flow information of the region of interest. Three kinds of RBFs are employed to acquire the coefficient matrix of the AT. It also adds the prior information of continuity into the flow field reconstruction. Modified Tikhonov regularization is introduced to reconstruct the velocity field which alleviates the severe ill-posedness of the acoustic tomography (AT) problem. The influence of shape parameters, types of RBF, and the collocation of central points on reconstruction are investigated. Proof-of-concept simulations and corresponding Tomographic PIV data based simulation verification are conducted to prove the feasibility and effectiveness of the proposed method in velocity field reconstruction. All these results confirm that it is appropriate to solve severely ill-posed and underdetermined AT problems and in recovering the velocity field distribution.
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The objective of this paper is to explore the relationship between the characteristics of plastic particles in suspension and acoustic impedance spectrum and to present a novel non-invasive methodology for both spherical and non-spherical... more
The objective of this paper is to explore the relationship between the characteristics of plastic particles in suspension and acoustic impedance spectrum and to present a novel non-invasive methodology for both spherical and non-spherical particle sizing. By modifying the ultrasonic attenuation spectral model, theories relating acoustic impedance spectrum to particle characteristics have been established to implement quite a few numerical simulations for the first time, revealing that the acoustic impedance of plastic particles is sensitive to changes in particle concentration and size. Afterwards, experiments were carried out on polystyrene suspensions made by particles with different sizes. On the basis of the theoretical analysis, different transducers were employed over a frequency varied from 10MHz to 100MHz for different particle sizes respectively. Not only were spherical particles chosen for the experiment, but also non-spherical particles with three different size distribut...
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The THGEMs based on ceramic substrate were developed successfully for neutron and single photon detection. The influences on thermal neutron scattering and the internal radioactivity of both ceramic and FR-4 substrates were studied and... more
The THGEMs based on ceramic substrate were developed successfully for neutron and single photon detection. The influences on thermal neutron scattering and the internal radioactivity of both ceramic and FR-4 substrates were studied and compared. The ceramic THGEMs are homemade of 200 um hole diameter, 600 um pitch, 200 um thickness, 80 um rim, and 50 mm*50 mm sensitive area. The FR-4 THGEMs with the same geometry were used for the reference. The gas gain, energy resolution and gain stability were measured in different gas mixtures by using the 5.9 keV X-rays. The maximum gain of single layer ceramic THGEM reaches 6*104 and 1.5*104 at Ne+CH4 = 95:5 and Ar+i-C4H10 = 97:3, respectively. The energy resolution is better than 24%. The good gain stability was obtained during more than 100 hour continuous test at Ar+CO2 = 80:20. By using the 239Pu source, the alpha deposited energy spectrum and gain curve of ceramic THGEM were measured.
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ABSTRACT A fiber-based two-line tunable diode-laser absorption sensor with two near-infrared (NIR) distributed-feedback (DFB) diode lasers at ̃1.4 μm was used for non-intrusive time-resolved liquid water film thickness measurement. When... more
ABSTRACT A fiber-based two-line tunable diode-laser absorption sensor with two near-infrared (NIR) distributed-feedback (DFB) diode lasers at ̃1.4 μm was used for non-intrusive time-resolved liquid water film thickness measurement. When probing the liquid film at two different wavelengths with significantly different absorption cross-sections, the additional signal losses due to surface fowling, reflection and beam steering can be eliminated. In this work, the evaporation process of a liquid film on transparent quartz plate was tracked and large fluctuations of film thickness were found at the end of the evaporation.
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ABSTRACT A system based on trajectory image processing is developed to achieve in situ measurement of particle size, concentration and velocity in dilute gas-liquid two-phase flow, which is hard to be measured by laser particle analyzer.... more
ABSTRACT A system based on trajectory image processing is developed to achieve in situ measurement of particle size, concentration and velocity in dilute gas-liquid two-phase flow, which is hard to be measured by laser particle analyzer. As the single-frame single-exposure image method, velocities of droplets can be easily calculated from the certain exposure time and the moving distance in a trajectory image, avoiding cross-correlation processing. A telecentric lens is used as an important component of the measurement system which can help to get concentration information. This in situ method avoids inversed processes in measurement methods such as light fluctuation method. Particles with defocused blur are also dealt with in the later part of the paper for further investigation of particle size and concentration measurement.
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Spectral technology has become an important detection method due to its advantages such as nonintrusive measurement and on-line analysis. In this paper, two applications of spectral technology in thermal detection were proposed. First, a... more
Spectral technology has become an important detection method due to its advantages such as nonintrusive measurement and on-line analysis. In this paper, two applications of spectral technology in thermal detection were proposed. First, a novel spectroscopic method based on Planck’s law for measurement of emissivity was introduced. The emissivity, obtained by comparing the radiation intensity of the blackbody which had the same temperature as the flame with the detected intensity of the flames, could be used for on-line measurements and had a relatively higher upper temperature limit. Then, a spectroscopic method for composition detection of blended fuels was proposed based on the emissivity measured. By comparing the spectra of blended fuels and single fuels, the ratio of single fuels of the blended fuel could be calculated. The measurement system proposed in this paper, which consists of a spectrometer and a computer, is very compact.
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The unburned carbon particle, formed due to incomplete combustion of fossil fuel, biofuel, and biomass, raises great environmental and health problems. During the measurement of flames, a non-intrusive and in situ optical method is... more
The unburned carbon particle, formed due to incomplete combustion of fossil fuel, biofuel, and biomass, raises great environmental and health problems. During the measurement of flames, a non-intrusive and in situ optical method is preferred rather than probe sampling method. Also the method with high spatial resolution and high temporal resolution is required for fast dynamic reactions such as combustion research. The technique based on laser-induced incandescence (LII) has been developed to characterize the soot particles. In this work, the simulation of LII signals have been did. In the simulation, different parameters have been applied and acquired corresponding results. The method provides theoretical results to analyze LII signals, and will eventually use in experimentation
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By investigating the surface wave of photonic crystal, we put forward two sets of rules: the right-handed screw rule, judging the transverse spin angular momentum (SAM) directions according to the propagation direction of the surface... more
By investigating the surface wave of photonic crystal, we put forward two sets of rules: the right-handed screw rule, judging the transverse spin angular momentum (SAM) directions according to the propagation direction of the surface wave; and the left-handed rule, judging the excitation direction of the surface wave in accordance to the SAM direction of incident circularly polarized light and the relative position of the dipole-like scatterer with respect to the interface where the surface wave propagates. Both right- and left-handed rules apply to the interface consisting of opposite-sign-permittivity materials. With the help of these two sets of rules, it is convenient to judge the direction of the transverse SAM and the excited surface wave, which facilitate the application involving transverse SAM of the surface wave.