This study describes the development of novel protocols extending the real-time ultrasonic reflectometry(UTDR) for the detection of membrane fouling in hollow fiber module during ultrafiltration(UF) of oily water trea...This study describes the development of novel protocols extending the real-time ultrasonic reflectometry(UTDR) for the detection of membrane fouling in hollow fiber module during ultrafiltration(UF) of oily water treatment. A specially designed acoustic sensor with a frequency of 2.5 MHz was used. The hollow fiber membranes used were polysulphone(PSf) UF membranes with MWCO 40 kDa. The wastewaters with three different oily concentrations of 100, 500 and 1 000 mg/L were investigated. Diesel oil was utilized as the primary foulant. The results show that the permeate flux declines with operation time and its value becomes lower with the increase of the oily concentration in wastewater. It is found that ultrasonic measurement can detect the fouling and cleaning processes. A new signal analysis protocol-ultrasonic reflected energy was developed. Ultrasonic reflected energy obtained indicates the deposition of oily layer as a function of operation time and its removal after cleaning. The overall flux decline is reasonably correlated with the changes in ultrasonic reflected energy. This research provides the evidence that the ultrasonic reflectometry technique is capable of monitoring membrane fouling and cleaning in hollow fiber modules.展开更多
天然气水合物饱和度是评估天然气水合物资源量的重要参数,而用来估算饱和度的速度模型则是有限的几个,它们有的为经验公式,有的是以实验数据或野外资料为基础建立起来的,需要进行实验验证和参数分析以确定其使用的适用性.本文首次利用...天然气水合物饱和度是评估天然气水合物资源量的重要参数,而用来估算饱和度的速度模型则是有限的几个,它们有的为经验公式,有的是以实验数据或野外资料为基础建立起来的,需要进行实验验证和参数分析以确定其使用的适用性.本文首次利用超声和时域反射联合探测技术,研究了沉积物中水合物饱和度与声学特性的关系.并对时间平均方程、伍德及其修正方程、李权重方程和BGTL(Biot-Gassmann Theory by Lee)理论等常用的水合物饱和度估算模型进行了验证.实验结果表明,超声和时域反射联合探测技术能有效地实时获得水合物饱和度和纵、横波速的实验数据,李权重方程和BGTL理论的速度预测值与实验值比较吻合,有广泛的适用性.展开更多
A distributed optical-fiber acoustic sensor is an acoustic sensor that uses the optical fiber itself as a photosensitive medium,and is based on Rayleigh backscattering in an optical fiber.The sensor is widely used in ...A distributed optical-fiber acoustic sensor is an acoustic sensor that uses the optical fiber itself as a photosensitive medium,and is based on Rayleigh backscattering in an optical fiber.The sensor is widely used in the safety monitoring of oil and gas pipelines,the classification of weak acoustic signals,defense,seismic prospecting,and other fields.In the field of seismic prospecting,distributed optical-fiber acoustic sensing(DAS)will gradually replace the use of the traditional geophone.The present paper mainly expounds the recent application of DAS,and summarizes recent research achievements of DAS in resource exploration,intrusion monitoring,pattern recognition,and other fields and various DAS system structures.It is found that the high-sensitivity and long-distance sensing capabilities of DAS play a role in the extensive monitoring applications of DAS in engineering.The future application and development of DAS technology are examined,with the hope of promoting the wider application of the DAS technology,which benefits engineering and society.展开更多
A quasi-distributed Fabry-Perot fiber optic temperature sensor array using optical time domain reflectometry （OTDR） technique is presented. The F-P sensor is made by two face to face single-mode optical fibers and t...A quasi-distributed Fabry-Perot fiber optic temperature sensor array using optical time domain reflectometry （OTDR） technique is presented. The F-P sensor is made by two face to face single-mode optical fibers and their surfaces have been polished. Due to the low reflectivity of the fiber surfaces, the sensor is described as low Fresnel Fabry-Perot interferometer （FPI）. The working principle is analyzed using twobeam optical interference approximation. To measure the temperature, a certain temperature sensitive material is filled in the cavity. The slight changes of the reflective intensity which is induced by the refractive index of the material was caught by OTDR. The length of the cavity is obtained by monitoring the interference spectrum which is used for the setting of the sensor static characteristics within the quasi-linear range. Based on our design, a three point sensor array are fabricated and characterized. The experimental results show that with the temperature increasing from -30℃ to 80℃, the reflectivity increase in a good linear manner. The sensitivity was approximate 0.074 dB℃. For the low transmission loss, more sensors can be integrated.展开更多
Auto-regressive （AR） spectral estimation technology is proposed to analyze the Brillouin scattering spectrum in Brillouin optical time-domain refelectometry. It shows that AR based method can reliably estimate the B...Auto-regressive （AR） spectral estimation technology is proposed to analyze the Brillouin scattering spectrum in Brillouin optical time-domain refelectometry. It shows that AR based method can reliably estimate the Brillouin frequency shift with an accuracy much better than fast Fourier transform （FFT） based methods provided the data length is not too short. It enables about 3 times improvement over FFT at a moderate spatial resolution.展开更多
The time-domain reflectometry technique was exercised to assess the complex permittivities of 1-chloropropane and ethanol along with their binary mixture in the frequency range of 10MHz–50 GHz and in the temperature ...The time-domain reflectometry technique was exercised to assess the complex permittivities of 1-chloropropane and ethanol along with their binary mixture in the frequency range of 10MHz–50 GHz and in the temperature range of 10–25℃.Dielectric parameters like static dielectric permittivity(ε_(0))and relaxation time(τ)have been acquired by the least-square-fit method.The obtained assessments of static permittivity and relaxation time were used to compute various dielectric parameters like excess dielectric constant,excess relaxation time,Kirkwood correlation factor and thermodynamic parameters.The experimental outcome illustrates the nonlinear variations in dielectric permittivity,relaxation time and authenticates the structural formation due to intermolecular interaction between 1-chloropropane and ethanol.Molecular rotary motion and dipole reorientation movements of these complex systems are presented in agreement with the molar entropy and enthalpy.展开更多
基金Project supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry of China Projects(043612611, 05YFGDGX10000) supported by the Natural Science Foundation and Development Program of Science and Technology of Tianjin, China
文摘This study describes the development of novel protocols extending the real-time ultrasonic reflectometry(UTDR) for the detection of membrane fouling in hollow fiber module during ultrafiltration(UF) of oily water treatment. A specially designed acoustic sensor with a frequency of 2.5 MHz was used. The hollow fiber membranes used were polysulphone(PSf) UF membranes with MWCO 40 kDa. The wastewaters with three different oily concentrations of 100, 500 and 1 000 mg/L were investigated. Diesel oil was utilized as the primary foulant. The results show that the permeate flux declines with operation time and its value becomes lower with the increase of the oily concentration in wastewater. It is found that ultrasonic measurement can detect the fouling and cleaning processes. A new signal analysis protocol-ultrasonic reflected energy was developed. Ultrasonic reflected energy obtained indicates the deposition of oily layer as a function of operation time and its removal after cleaning. The overall flux decline is reasonably correlated with the changes in ultrasonic reflected energy. This research provides the evidence that the ultrasonic reflectometry technique is capable of monitoring membrane fouling and cleaning in hollow fiber modules.
文摘天然气水合物饱和度是评估天然气水合物资源量的重要参数,而用来估算饱和度的速度模型则是有限的几个,它们有的为经验公式,有的是以实验数据或野外资料为基础建立起来的,需要进行实验验证和参数分析以确定其使用的适用性.本文首次利用超声和时域反射联合探测技术,研究了沉积物中水合物饱和度与声学特性的关系.并对时间平均方程、伍德及其修正方程、李权重方程和BGTL(Biot-Gassmann Theory by Lee)理论等常用的水合物饱和度估算模型进行了验证.实验结果表明,超声和时域反射联合探测技术能有效地实时获得水合物饱和度和纵、横波速的实验数据,李权重方程和BGTL理论的速度预测值与实验值比较吻合,有广泛的适用性.
基金supported by the Science and Technology Development Plan of Jilin Province(No.20180201036GX)
文摘A distributed optical-fiber acoustic sensor is an acoustic sensor that uses the optical fiber itself as a photosensitive medium,and is based on Rayleigh backscattering in an optical fiber.The sensor is widely used in the safety monitoring of oil and gas pipelines,the classification of weak acoustic signals,defense,seismic prospecting,and other fields.In the field of seismic prospecting,distributed optical-fiber acoustic sensing(DAS)will gradually replace the use of the traditional geophone.The present paper mainly expounds the recent application of DAS,and summarizes recent research achievements of DAS in resource exploration,intrusion monitoring,pattern recognition,and other fields and various DAS system structures.It is found that the high-sensitivity and long-distance sensing capabilities of DAS play a role in the extensive monitoring applications of DAS in engineering.The future application and development of DAS technology are examined,with the hope of promoting the wider application of the DAS technology,which benefits engineering and society.
基金funded by the National Natural Science Foundation of China under Grant No. 60677031 and 60577043the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No. 20060280001+1 种基金Shanghai Education Commission under Grant No. 06AZ032, Chenguang Program under Grant No. 2007CG54Science and Technology Commission of Shanghai Municipality (STCSM) under Grant No. 07DZ22024 and 075307017
文摘A quasi-distributed Fabry-Perot fiber optic temperature sensor array using optical time domain reflectometry （OTDR） technique is presented. The F-P sensor is made by two face to face single-mode optical fibers and their surfaces have been polished. Due to the low reflectivity of the fiber surfaces, the sensor is described as low Fresnel Fabry-Perot interferometer （FPI）. The working principle is analyzed using twobeam optical interference approximation. To measure the temperature, a certain temperature sensitive material is filled in the cavity. The slight changes of the reflective intensity which is induced by the refractive index of the material was caught by OTDR. The length of the cavity is obtained by monitoring the interference spectrum which is used for the setting of the sensor static characteristics within the quasi-linear range. Based on our design, a three point sensor array are fabricated and characterized. The experimental results show that with the temperature increasing from -30℃ to 80℃, the reflectivity increase in a good linear manner. The sensitivity was approximate 0.074 dB℃. For the low transmission loss, more sensors can be integrated.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 11474133 and 61235005） and Science and Technology Program of Guangzhou （No. 201707010338）.
文摘Auto-regressive （AR） spectral estimation technology is proposed to analyze the Brillouin scattering spectrum in Brillouin optical time-domain refelectometry. It shows that AR based method can reliably estimate the Brillouin frequency shift with an accuracy much better than fast Fourier transform （FFT） based methods provided the data length is not too short. It enables about 3 times improvement over FFT at a moderate spatial resolution.
基金the Department of Science and Technology(DST),New Delhi,is gratefully acknowledged(Project No.DST PROJECT-SB/S2/LOP-032/2013).
文摘The time-domain reflectometry technique was exercised to assess the complex permittivities of 1-chloropropane and ethanol along with their binary mixture in the frequency range of 10MHz–50 GHz and in the temperature range of 10–25℃.Dielectric parameters like static dielectric permittivity(ε_(0))and relaxation time(τ)have been acquired by the least-square-fit method.The obtained assessments of static permittivity and relaxation time were used to compute various dielectric parameters like excess dielectric constant,excess relaxation time,Kirkwood correlation factor and thermodynamic parameters.The experimental outcome illustrates the nonlinear variations in dielectric permittivity,relaxation time and authenticates the structural formation due to intermolecular interaction between 1-chloropropane and ethanol.Molecular rotary motion and dipole reorientation movements of these complex systems are presented in agreement with the molar entropy and enthalpy.
