The instantaneous speed of a hydraulic system contains a wealth of operational information,and its accurate extraction is the basis for condition monitoring and fault diagnosis.In order to solve the problem of high ha...The instantaneous speed of a hydraulic system contains a wealth of operational information,and its accurate extraction is the basis for condition monitoring and fault diagnosis.In order to solve the problem of high hardware requirement for instantaneous speed measurement based on data acquisition card,a new method of high precision measurement is proposed.In this method,the time-displacement information of each tooth is obtained from the pulsed square wave signal of the gear disk collected by magnetoelectric sensors.The time-displacement curve is interpolated by the cubic spline interpolation method,and then the instantaneous speed is calculated by the five-point digital differential formula.The experimental results show that the method improves the speed measurement resolution and reduces the quantization error.The high precision instantaneous speed signal can also be acquired by hardware devices with less teeth and low sampling frequency.The related research results provide a theoretical basis and a method for improving the accuracy of instantaneous speed measurement.展开更多
Short path distillation (SPD) is a kind of high vacuum distillation method, which is suitable for the separation of high boiling, heat sensitivity and viscidity products.In this paper,through measuring the phase-avera...Short path distillation (SPD) is a kind of high vacuum distillation method, which is suitable for the separation of high boiling, heat sensitivity and viscidity products.In this paper,through measuring the phase-averaged velocity distributions with a conditional sampling method of the particle imaging velocimetry (PIV), the liquid flow field that affects the heat and mass transfer of evaporating thin-film in an SPD evaporator is investigated.Measured results show that the flow velocities decrease rapidly apart from the wiper at different wiper velocities, the maximum velocity appears before wipers, and the quicker the wiping, the larger the flow velocity. Meanwhile, the evaluation of numerical calculations is carried out.The measured velocity distributions indicate clearly the effect of the wiper both on the flow field along its moving direction and on the vortices behind the wiper.Simulation data show that the performance of liquid flow field on the heating surface not only agrees with the experimental results well,but also can give further more information, such as the distribution of turbulent kinetic energy.In this study,turbulent kinetic energy mainly distributes before wipers and laminar flow appears far away from the wipers.展开更多
Particle image velocimetry technique was used to analyze the trailing vortices and elucidate their rela-tionship with turbulence properties in a stirred tank of 0.48 m diameter,agitated by four different disc turbines...Particle image velocimetry technique was used to analyze the trailing vortices and elucidate their rela-tionship with turbulence properties in a stirred tank of 0.48 m diameter,agitated by four different disc turbines,in-cluding Rushton turbine,concaved blade disk turbine,half elliptical blade disk turbine,and parabolic blade disk turbine.Phase-averaged and phase-resolved flow fields near the impeller blades were measured and the structure of trailing vortices was studied in detail.The location,size and strength of vortices were determined by the simplified λ2-criterion and the results showed that the blade shape had great effect on the trailing vortex characteristics.The larger curvature resulted in longer residence time of the vortex at the impeller tip,bigger distance between the upper and lower vortices and longer vortex life,also leads to smaller and stronger vortices.In addition,the turbulent ki-netic energy and turbulent energy dissipation in the discharge flow were determined and discussed.High turbulent kinetic energy and turbulent energy dissipation regions were located between the upper and lower vortices and moved along with them.Although restricted to single phase flow,the presented results are essential for reliable de-sign and scale-up of stirred tank with disc turbines.展开更多
Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received cons...Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received considerable attention and has been investigated extensively. However, the detailed flow structure in the shell needs to be determined for reliable and effective design. Therefore, the objective of this study was to clarify the flow structure in shell by particle image velocimetry （PIV）. Experiments were conducted using two types of model; 15% baffle cut having inlet and outlet positions !n the direction of 90° to the cut and 30% baffle cut having inlet and outlet positions in the direction of 180° to the cut. Each test section is 169 mm in inner diameter and 344.6 mm in length. The flow features were characterized in different baffle cuts with regards to the velocity vector field and velocity distribution. The results show that the flow characteristics of 15% baffle cut type vaporizer are comparable to those of 30% baffle cut type vaporizer.展开更多
This review gives a short introduction into the principles of ultrasonic measurement techniques for liquids, using cavity resonators. Guidelines for the resonator design in broad-band ultrasonic stxctroscopy as well a...This review gives a short introduction into the principles of ultrasonic measurement techniques for liquids, using cavity resonators. Guidelines for the resonator design in broad-band ultrasonic stxctroscopy as well as in high-resolution single-frequncy or narrowband applications are presented. Deviations of the field configuration in real cells frtxn that in an ideal resonator are discussed and relations for the mode spectrum of cavity fields are given. Recent resonator measurement procedures and methods of data evaluation are mentioned briefly. Some examples of measurements show the extended usability of ultrasonic resonator techniques in basic science and in a wide range of applications for rrkaterials characterization, in manufacturing processes, as well as in control routines.展开更多
The characterization of suspension/emulsion sprays plays a decisive role in many industrial processes. A good example of such a process is the drying of a milk spray to produce milk powder, where the process efficienc...The characterization of suspension/emulsion sprays plays a decisive role in many industrial processes. A good example of such a process is the drying of a milk spray to produce milk powder, where the process efficiency and product quality is typically controlled by atomization parameters like flow rate, pressure, etc.. However, these parameters influence directly the droplet size and droplet velocity distributions in a spray, so that optimizing a spray drying process often involves adjusting the spray to a desired droplet size and droplet velocity distribution. This requires a measurement technique capable of characterizing in real time, the droplets in a suspension/emulsion spray. To achieve this aim, we present developments to the well-known time-shift technique for spray measurements.展开更多
An efficient, sensitive, accurate and rapid analytical ultra-fast liquid chromatography （UFLC） method for quality evaluations ofPyrrosia petiolosa （Christ） Ching from 20 regions of China was developed in this stud...An efficient, sensitive, accurate and rapid analytical ultra-fast liquid chromatography （UFLC） method for quality evaluations ofPyrrosia petiolosa （Christ） Ching from 20 regions of China was developed in this study. Ten marker compounds were simultaneously quantified, including 5-caffeoylquinic acid （5-CQA）, 3-caffeoylquinic acid （3-CQA）, 4-caffeoylquinic acid （4-CQA）, 1-caffeoylquinic acid （1-CQA）, 3,5-dicaffeoylquinic acid （3,5-diCQA）, 4,5-dicaffeoylquinic acid （4,5-diCQA）, 3,4-dicaffeoylquinic acid （3,4-diCQA）, astragalin, kaempferol-3,7-di-O-glucoside and （±）eriodictyol-7-O-β-D-glucuronide. Chromatography was performed on a Kromasil 100-2.5C18 （100 mm×2.1 mm, 2.5 μm） C18 column with gradient elution. The mobile phases consisted of 0.1% formic acid/water （A） and 0.1% formic acid/methanol （B）. The detection wavelength was set at 326 nm and the flow rate was 0.4 mL/min. Ten components were separated well with good linearity （r2〉0.9998）, precision, repeatability, stability. The recovery was in the range of 99.08%-102.77%. The results showed that the content determination using RP-UFLC-DAD fingerprint technique provides an efficient, sensitive, accurate and rapid analytical method for quality assessment ofP. petiolosa （Christ） Ching. Cluster analysis and principal components analysis were successfully applied to analyze 20 samples, the results revealed that the method was efficient and authentic to distinguish producing areas and the source of P. petiolosa （Christ） Ching. Keywords： Pyrrosiapetiolosa （Christ） Ching, Caffeoylquinic acids, Flavonoids, Multicomponent determination, UFLC展开更多
基金National Natural Science Foundation of China(No.51275375)Scientific Research Program Project of Shaanxi Provincial Education Department(No.19JK0464)
文摘The instantaneous speed of a hydraulic system contains a wealth of operational information,and its accurate extraction is the basis for condition monitoring and fault diagnosis.In order to solve the problem of high hardware requirement for instantaneous speed measurement based on data acquisition card,a new method of high precision measurement is proposed.In this method,the time-displacement information of each tooth is obtained from the pulsed square wave signal of the gear disk collected by magnetoelectric sensors.The time-displacement curve is interpolated by the cubic spline interpolation method,and then the instantaneous speed is calculated by the five-point digital differential formula.The experimental results show that the method improves the speed measurement resolution and reduces the quantization error.The high precision instantaneous speed signal can also be acquired by hardware devices with less teeth and low sampling frequency.The related research results provide a theoretical basis and a method for improving the accuracy of instantaneous speed measurement.
文摘Short path distillation (SPD) is a kind of high vacuum distillation method, which is suitable for the separation of high boiling, heat sensitivity and viscidity products.In this paper,through measuring the phase-averaged velocity distributions with a conditional sampling method of the particle imaging velocimetry (PIV), the liquid flow field that affects the heat and mass transfer of evaporating thin-film in an SPD evaporator is investigated.Measured results show that the flow velocities decrease rapidly apart from the wiper at different wiper velocities, the maximum velocity appears before wipers, and the quicker the wiping, the larger the flow velocity. Meanwhile, the evaluation of numerical calculations is carried out.The measured velocity distributions indicate clearly the effect of the wiper both on the flow field along its moving direction and on the vortices behind the wiper.Simulation data show that the performance of liquid flow field on the heating surface not only agrees with the experimental results well,but also can give further more information, such as the distribution of turbulent kinetic energy.In this study,turbulent kinetic energy mainly distributes before wipers and laminar flow appears far away from the wipers.
基金Supported by the National Natural Science Foundation of China（20776008 20821004 20990224） the National Basic Research Program of China（2007CB714300）
文摘Particle image velocimetry technique was used to analyze the trailing vortices and elucidate their rela-tionship with turbulence properties in a stirred tank of 0.48 m diameter,agitated by four different disc turbines,in-cluding Rushton turbine,concaved blade disk turbine,half elliptical blade disk turbine,and parabolic blade disk turbine.Phase-averaged and phase-resolved flow fields near the impeller blades were measured and the structure of trailing vortices was studied in detail.The location,size and strength of vortices were determined by the simplified λ2-criterion and the results showed that the blade shape had great effect on the trailing vortex characteristics.The larger curvature resulted in longer residence time of the vortex at the impeller tip,bigger distance between the upper and lower vortices and longer vortex life,also leads to smaller and stronger vortices.In addition,the turbulent ki-netic energy and turbulent energy dissipation in the discharge flow were determined and discussed.High turbulent kinetic energy and turbulent energy dissipation regions were located between the upper and lower vortices and moved along with them.Although restricted to single phase flow,the presented results are essential for reliable de-sign and scale-up of stirred tank with disc turbines.
基金supported by the National Research Foundation of Korea Grant funded by the Korean Government (NRF-2010-013-D00007)2010 Research Professor Fund of Gyeongsang National University,Korea
文摘Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received considerable attention and has been investigated extensively. However, the detailed flow structure in the shell needs to be determined for reliable and effective design. Therefore, the objective of this study was to clarify the flow structure in shell by particle image velocimetry （PIV）. Experiments were conducted using two types of model; 15% baffle cut having inlet and outlet positions !n the direction of 90° to the cut and 30% baffle cut having inlet and outlet positions in the direction of 180° to the cut. Each test section is 169 mm in inner diameter and 344.6 mm in length. The flow features were characterized in different baffle cuts with regards to the velocity vector field and velocity distribution. The results show that the flow characteristics of 15% baffle cut type vaporizer are comparable to those of 30% baffle cut type vaporizer.
文摘This review gives a short introduction into the principles of ultrasonic measurement techniques for liquids, using cavity resonators. Guidelines for the resonator design in broad-band ultrasonic stxctroscopy as well as in high-resolution single-frequncy or narrowband applications are presented. Deviations of the field configuration in real cells frtxn that in an ideal resonator are discussed and relations for the mode spectrum of cavity fields are given. Recent resonator measurement procedures and methods of data evaluation are mentioned briefly. Some examples of measurements show the extended usability of ultrasonic resonator techniques in basic science and in a wide range of applications for rrkaterials characterization, in manufacturing processes, as well as in control routines.
文摘The characterization of suspension/emulsion sprays plays a decisive role in many industrial processes. A good example of such a process is the drying of a milk spray to produce milk powder, where the process efficiency and product quality is typically controlled by atomization parameters like flow rate, pressure, etc.. However, these parameters influence directly the droplet size and droplet velocity distributions in a spray, so that optimizing a spray drying process often involves adjusting the spray to a desired droplet size and droplet velocity distribution. This requires a measurement technique capable of characterizing in real time, the droplets in a suspension/emulsion spray. To achieve this aim, we present developments to the well-known time-shift technique for spray measurements.
基金Study of Safety Testing Techniques and Standards on New Traditional Chinese Drug(National Key Science and Technology Special Projects,Grant No.2014ZX09304307-001-001)
文摘An efficient, sensitive, accurate and rapid analytical ultra-fast liquid chromatography （UFLC） method for quality evaluations ofPyrrosia petiolosa （Christ） Ching from 20 regions of China was developed in this study. Ten marker compounds were simultaneously quantified, including 5-caffeoylquinic acid （5-CQA）, 3-caffeoylquinic acid （3-CQA）, 4-caffeoylquinic acid （4-CQA）, 1-caffeoylquinic acid （1-CQA）, 3,5-dicaffeoylquinic acid （3,5-diCQA）, 4,5-dicaffeoylquinic acid （4,5-diCQA）, 3,4-dicaffeoylquinic acid （3,4-diCQA）, astragalin, kaempferol-3,7-di-O-glucoside and （±）eriodictyol-7-O-β-D-glucuronide. Chromatography was performed on a Kromasil 100-2.5C18 （100 mm×2.1 mm, 2.5 μm） C18 column with gradient elution. The mobile phases consisted of 0.1% formic acid/water （A） and 0.1% formic acid/methanol （B）. The detection wavelength was set at 326 nm and the flow rate was 0.4 mL/min. Ten components were separated well with good linearity （r2〉0.9998）, precision, repeatability, stability. The recovery was in the range of 99.08%-102.77%. The results showed that the content determination using RP-UFLC-DAD fingerprint technique provides an efficient, sensitive, accurate and rapid analytical method for quality assessment ofP. petiolosa （Christ） Ching. Cluster analysis and principal components analysis were successfully applied to analyze 20 samples, the results revealed that the method was efficient and authentic to distinguish producing areas and the source of P. petiolosa （Christ） Ching. Keywords： Pyrrosiapetiolosa （Christ） Ching, Caffeoylquinic acids, Flavonoids, Multicomponent determination, UFLC
