With the development of science and technology in China, the measuring technique in water resources and hydropower engineering is also developing constantly. Measuring technique in water resources and hydropower engin...With the development of science and technology in China, the measuring technique in water resources and hydropower engineering is also developing constantly. Measuring technique in water resources and hydropower engineering is an important link in water conservancy and hydropower projects, which can improve the survey efficiency of water conservancy and hydropower projects and promote the rapid development of China's water conservancy and hydropower projects. This paper will analyze the current situation of measuring technique development of water conservancy and hydropower projects and explore how to improve the measuring efficiency of water conservancy and hydropower projects.展开更多
A multi-function sampling system has been set up in Shanghai Ship & Shipping Research Institute (SSSRI) where a test on the fluctuating pressure of two propeller models were carried out. This paper deals with a st...A multi-function sampling system has been set up in Shanghai Ship & Shipping Research Institute (SSSRI) where a test on the fluctuating pressure of two propeller models were carried out. This paper deals with a study on the technical problems concerning the measurement and analysis techniques involved in the test. The sampling and processing procedure of signal is one of the major factors affecting the ac- curacy and stability of the prediction of fluctuating pressure induced by propeller. Integral-peri- od sampling, high enough sampling frequency and suitable resolution must be kept in sampling and processing. The procedure of sampling and processing should be validated by standard signal corresponding to the blade frequency of different orders in comparative tests.展开更多
In many situations such as the cores of a rotating electrical machine and the T joints of a multiphase transformer, the local flux density varies with time in terms of both magnitude and direction, i.e. the flux densi...In many situations such as the cores of a rotating electrical machine and the T joints of a multiphase transformer, the local flux density varies with time in terms of both magnitude and direction, i.e. the flux density vector is rotating. Therefore, the magnetic properties of the core materials under the rotating flux density vector excitation should be properly measured, modeled and applied in the design and analysis of these electromagnetic devices. This paper presents an extensive review on the development of techniques and apparatus for measuring the rotational core losses of soft magnetic materials based on the experiences of various researchers in the last hundred years.展开更多
The purpose of this study is to develop a standard methodology for measuring the surface free energy (SFE),and its component parts of bamboo fiber materials.The current methods was reviewed to determine the surface te...The purpose of this study is to develop a standard methodology for measuring the surface free energy (SFE),and its component parts of bamboo fiber materials.The current methods was reviewed to determine the surface tension of natural fibers and the disadvantages of techniques used were discussed.Although numerous techniques have been employed to characterize surface tension of natural fibers,it seems that the credibility of results obtained may often be dubious.In this paper,critical surface tension estimates were obtained from computer aided machine vision based measurement.Data were then analyzed by the least squares method to estimate the components of SFE.SFE was estimated by least squares analysis and also by Schultz' method.By using the Fowkes method the polar and disperse fractions of the surface free energy of bamboo fiber materials can be obtained.Strictly speaking,this method is based on a combination of the knowledge of Fowkes theory. SFE is desirable when adhesion is required,and it avoids some of the limitations of existing studies which has been proposed.The calculation steps described in this research are only intended to explain the methods.The results show that the method that only determines SFE as a single parameter may be unable to differentiate adequately between bamboo fiber materials,but it is feasible and very efficient.In order to obtain the maximum performance from the computer aided machine vision based measurement instruments,this measurement should be recommended and kept available for reference.展开更多
The velocity of blown sand particles is an important parameter in aeolian movement （a special case of gas particle two-phase flow） and has ever been a topic of interest. At present, several techniques have been appl...The velocity of blown sand particles is an important parameter in aeolian movement （a special case of gas particle two-phase flow） and has ever been a topic of interest. At present, several techniques have been applied in measuring velocity of the blown sand particles. This paper reviews the measurement results of several commonly used methods： photoelectric cell method, high-speed photographic method, Particle Dynamics Analyzer （PDA） method and Particle Image Velocimetry （PIV） method. Photoelectric cell method, high-speed photograph method and PDA method are useful in studying the velocity distribution of particles. PIV is a whole-flow-field technique and a useful tool to study the average velocity field in a target area. These methods got some similar results but considerable differences also exist. They have come to similar conclusions on the velocity distributions at a single height but direct measurement results with respect to the velocity distribution very close to the surface are still scarce except some PDA results. The magnitude of measured mean particle velocity differs greatly. The relationship obtained by different methods between mean particle velocity and wind velocity, particle size and possibly other influencing factors also differs considerably. Although several authors have proposed similar power functions to describe the variation with height of the mean particle velocity, the predicted results have wide differences. Each technique is based on some unique principles, and has its advantages and disad- vantages. To make full use of different techniques, a lot of work needs be done to validate them. Developing a reliable technique to measure the velocity of blown particles is still a necessary task in aeolian research.展开更多
Electrochemical techniques of the corrosion measurements of reinforcing steeI in concrete have been evaluated. These techniques include half-cell potential measurements, impressed voltage method, impressed current met...Electrochemical techniques of the corrosion measurements of reinforcing steeI in concrete have been evaluated. These techniques include half-cell potential measurements, impressed voltage method, impressed current method and potentiostatic polarization technique. The results of corrosion behaviour of the steel in both 5%NaCl and 5%MgSO4 show that each electrochemical technique provides some information about the condition of the steel bar or the corrosivity of the environment being evaluated, yet none provides a complete data regarding the corrosion resistance of reinforcing steel in aggressive media展开更多
Using the Differential Absorption Lidar (DIAL) technique, two types of approaches, namely, reflection from retroreflector / topographic target and backscatter from atmosphere, are available for studying remotely the a...Using the Differential Absorption Lidar (DIAL) technique, two types of approaches, namely, reflection from retroreflector / topographic target and backscatter from atmosphere, are available for studying remotely the atmospheric NO, concentration. The Argon ion lidar system at the Indian Institute of Tropical Meteorology (IITM), Pune, India has been used for the measurements by following both the path-averaged and range-resolved approaches. For the former, a topographic target (hill) is used for determining path-averaged surface concentration. In the latter, spectral properties of atmospheric attenuation is used for making range-resolved measurements in the surface layer. The results of the observations collected by following both approaches are presented. The average surface NO2 concentration was found to vary between 0.01 and 0.105 ppm and the range-resolved measurements exhibited higher values suggesting treatment of the lidar data for scattering and extinction effects due to atmospheric aerosols and air molecules, and atmospheric turbulence. Certain modifications that are suggested to the experimental set-up, data acquisition and analysis to improve the measurements are briefly described.展开更多
Recently, optical techniques have attracted great attention due to their excellent non-destructive, non-contact, high-resolution, and full-field characteristics. Applications can be found in diverse fields such as pre...Recently, optical techniques have attracted great attention due to their excellent non-destructive, non-contact, high-resolution, and full-field characteristics. Applications can be found in diverse fields such as precision mechanics and manufacturing, aerospace and automotive testing and inspection, materials science, and biomedical engineering. Advances in Optical Techniques for Me- chanical Measurements presents the latest research progresses in several widely used optical techniques with applications in preci- sion mechanical engineering.展开更多
By using dropped stress creep method a new testing technique for measurement of the fa-tigue-creep interaction resistance is developed. At varied adjusted mean stresses the creep testingwas performed repeatedly When a...By using dropped stress creep method a new testing technique for measurement of the fa-tigue-creep interaction resistance is developed. At varied adjusted mean stresses the creep testingwas performed repeatedly When an unlimited extensive incubation period with zero creep rate oc-curred. the stress cavsing zero creep rate is defined as fatigue-creep resistance. The developped test-ing technique was used to measure the fatigue-creep resistance in F anc C regions. The dynamic ef-fective stress could yield a better descrption of fatigue and creep interaction. The fatigue-creep rateequations with varied exponents inF of C region are established. The different deformation mecha-nisms in F or C regions are indicated展开更多
The^(6)Li+^(89)Y experiment was performed to explore the reaction mechanism induced by a weakly bound nucleus^(6)Li and its cluster configuration.The particle-γcoincidence method was used to identify the different re...The^(6)Li+^(89)Y experiment was performed to explore the reaction mechanism induced by a weakly bound nucleus^(6)Li and its cluster configuration.The particle-γcoincidence method was used to identify the different reaction channels.Theγ-rays coincident with^(3)He/^(3)H indicate that the^(3)H/^(3)He stripping reaction plays a significant role in the formation of Zr/Nb isotopes.The obtained results support the existence of a^(3)He-^(3)H cluster in^(6)Li.Direct and sequential transfer reactions are adequately discussed,and the FRESCO code is used to perform precise finite-range cyclic redundancy check calculations.In the microscopic calculation,direct cluster transfer is more predominant than sequential transfer in^(3)H transfer.However,the direct cluster transfer is of comparable magnitude to the sequential transfer in the^(3)He transfer.展开更多
A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted....A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted. The tests show that the ignitor and the main charge of the microthruster match well, the dynamic and static capability of the test and measurement meets the test requirement and the result is creditable. The measured technical characteristics of the microthruster are that the ignition delay time is shorter than 0 3?ms, the total impulse is over 3?N·s, the operational time is shorter than 16?ms and the mass ratio of the thruster is 0 216.展开更多
Beginning from the origination of the bone-length cun measurement, and proceeding from clinical application, the article differentiated and analyzed 4 measuring methods relate with cun, namely, bone-length cun measure...Beginning from the origination of the bone-length cun measurement, and proceeding from clinical application, the article differentiated and analyzed 4 measuring methods relate with cun, namely, bone-length cun measurement and finger cun measurement regarding to acupoint locating, cun measurement of filiform needle concerning the size of the body of the needle and cun measurement of acupuncture technique referring to the depth of insertion. It explained different senses of cun in the above 4 measurements. The original meaning and the respective implication for each situation should be clarified. Flexible and proper application is required so as to enhance the therapeutic effect of the treatment and avoid possible accidents.展开更多
This study explores the mathematical practices embedded in the cultural traditions of the Tharu community, with a focus on their counting systems, measuring techniques, and modeling patterns. Through ethnographic obse...This study explores the mathematical practices embedded in the cultural traditions of the Tharu community, with a focus on their counting systems, measuring techniques, and modeling patterns. Through ethnographic observations and field interviews, the research reveals how the Tharu people employ a base-20 counting system influenced by the Nepali numbering system and use physical objects for arithmetic operations. Their traditional measuring techniques rely on body-referenced units such as the Haat (hand) and Anguli (finger) for length, along with culturally specific units like the Muthi and Lota for volume. Additionally, the study examines the geometric patterns found in Tharu crafts, highlighting the community’s application of symmetry and ratios. The findings illustrate the significance of these ethnomathematical practices in the daily life of the Tharu people, offering insight into how indigenous mathematical knowledge can enrich the broader understanding of mathematics education. This research contributes to the field of ethnomathematics by documenting and analyzing the ways in which cultural groups integrate mathematical concepts to solve practical problems and preserve their heritage.展开更多
A fitting process is used to measure the cavity loss and the quasi Fermi level separation for Fabry Pérot semiconductor lasers.From the amplified spontaneous emission (ASE) spectrum,the gain spectrum and sing...A fitting process is used to measure the cavity loss and the quasi Fermi level separation for Fabry Pérot semiconductor lasers.From the amplified spontaneous emission (ASE) spectrum,the gain spectrum and single pass ASE obtained by the Cassidy method are applied in the fitting process.For a 1550nm quantum well InGaAsP ridge waveguide laser,the cavity loss of about ～24cm -1 is obtained.展开更多
Hypersonic and high-enthalpy wind tunnels and their measurement techniques are the cornerstone of the hypersonic flight era that is a dream for human beings to fly faster,higher and further.The great progress has been...Hypersonic and high-enthalpy wind tunnels and their measurement techniques are the cornerstone of the hypersonic flight era that is a dream for human beings to fly faster,higher and further.The great progress has been achieved during the recent years and their critical technologies are still in an urgent need for further development.There are at least four kinds of hypersonic and high-enthalpy wind tunnels that are widely applied over the world and can be classified according to their operation modes.These wind tunnels are named as air-directly-heated hypersonic wind tunnel,light-gas-heated shock tunnel,free-piston-driven shock tunnel and detonation-driven shock tunnel,respectively.The critical technologies for developing the wind tunnels are introduced in this paper,and their merits and weakness are discussed based on wind tunnel performance evaluation.Measurement techniques especially developed for high-enthalpy flows are a part of the hypersonic wind tunnel technology because the flow is a chemically reacting gas motion and its diagnosis needs specially designed instruments.Three kinds of the measurement techniques considered to be of primary importance are introduced here,including the heat flux sensor,the aerodynamic balance,and optical diagnosis techniques.The techniques are developed usually for conventional wind tunnels,but further improved for hypersonic and high-enthalpy tunnels.The hypersonic ground test facilities have provided us with most of valuable experimental data on high-enthalpy flows and will play a more important role in hypersonic research area in the future.Therefore,several prospects for developing hypersonic and high-enthalpy wind tunnels are presented from our point of view.展开更多
The LaBr3(Ce)detector has attracted much attention in recent years because of its superior characteristics compared with other scintillating materials in terms of resolution and efficiency.However,it has a relatively ...The LaBr3(Ce)detector has attracted much attention in recent years because of its superior characteristics compared with other scintillating materials in terms of resolution and efficiency.However,it has a relatively high intrinsic background radiation because of the naturally occurring radioisotopes in lanthanum,actinium,and their daughter nuclei.This limits its applications in low-counting rate experiments.In this study,we identified the radioactive isotopes in theφ3"x 3"Saint-Gobain B380 detector by a coincidence measurement using a Clover detector in a low-background shielding system.Moreover,we carried out a Geant4 simulation of the experimental spectra to evaluate the activities of the main internal radiation components.The total activity of the background radiation of B380 is determined to be 1.523(34)Bq/cm^3.The main sources include 138La at 1.428(34)Bq/cm^3,207Tl at 0.0135(13)Bq/cm^3,211Bi at 0.0136(15)Bq/cm^3,215Po at 0.0135(3)Bq/cm^3,219Rn at 0.0125(12)Bq/cm^3,223Fr at 0.0019(11)Bq/cm^3,223Ra at 0.0127(10)Bq/cm^3,227Th at 0.0158(22)Bq/cm^3,and 227Ac at 0.0135(13)Bq/cm^3.Of these,the activities of 207Tl,211Po,215Po,223Fr,and 227Ac are deduced for the first time from the secular equilibrium established in the decay chain of 227Ac.展开更多
Inductance-bared electromagnetic tomography (EMT) is a novel industrial process tomographic technique. Exact expressions of the magnetic field distribution in a two-dimensional object space were derived by analyticall...Inductance-bared electromagnetic tomography (EMT) is a novel industrial process tomographic technique. Exact expressions of the magnetic field distribution in a two-dimensional object space were derived by analytically solving the forward problem for a particular two-component pow. The physical mechanisms within the sensor and the detectability limits of the EMT technique were quantitatively analyzed. Direct mathematical expressions for the field sensitivity and the sensitivity maps were established. To a certain extent, mathematical and theoretical bares are given for quantitative design of the sensor, detectability analysis of the EMT technique and image reconstruction of two-component processes based on the linear back-projection algorithm.展开更多
Cadmium is one of the important contaminative heavy metals. Due to continuous increase of discharge of Cadmium in industrial and agriculture production, cadmium contamination of soil is more and more serious day by da...Cadmium is one of the important contaminative heavy metals. Due to continuous increase of discharge of Cadmium in industrial and agriculture production, cadmium contamination of soil is more and more serious day by day, which seriously threatens ecological environment and human health. Treatment of cadmium becomes an urgent issue and research hot point. At present, remedy for cadmium pollution upon soil mainly are physical restoration, chemical restoration and biological restoration, also there are measurements by means of adding external source matter and selecting low-Cd-accumulation varieties so as to reduce cadmium harm upon agricultural products. This article introduces in detail the resource of cadmium in soil and the present condition of cadmium pollution in farmland and processing of domestic cadmium pollution research, processing stage of domestic and foreign research of restoration of cadmium polluted soil as well as various peculiarities of repair methods. Finally, the expectation of research is discussed.展开更多
Quasi-longitudinal waves are one type of structural waves, which are important at high frequencies. This paper studies the estimate theory and measurement technique of quasi-longitudinal waves, analyzes the bias error...Quasi-longitudinal waves are one type of structural waves, which are important at high frequencies. This paper studies the estimate theory and measurement technique of quasi-longitudinal waves, analyzes the bias error due to the effect of bending waves. In a two-dimensional quasi-longitudinal wave held, the intensity vector is the sum of the effective intensity vector and the intensity variation vector. Its axial component is proportional to two imaginary parts of cross spectral densities and in the measurement, it is measured by a pair of two-transducer arrays. In a one-dimensional quasi-longitudinal wave field, the intensity variation is zero, the intensity is proportional to only one imaginary part of a cross spectral density and it can be measured using a two-transducer array. If bending and quasi-longitudinal waves coexist and the contribution from bending waves cannot be eliminated or reduced to a certain extent, the measured quasi-longitudinal wave intensity will contain a large error. The results measured on the three-beam structure show that quasi-longitudinal wave intensity can be accurately measured using the intensity technique when bending waves are negligible in comparison with quasi-longitudinal waves.展开更多
The influence of pH and metallographic structure on the corrosion behavior of copper-drawn steel is studied with the simulated system.The effect of pH on the corrosion behavior of copper-drawn steel has been investiga...The influence of pH and metallographic structure on the corrosion behavior of copper-drawn steel is studied with the simulated system.The effect of pH on the corrosion behavior of copper-drawn steel has been investigated using open-circuit potential,potentiodynamic polarization,galvanic current measurement,scanning electron microscopy and scanning vibrating electrode technique techniques.The steel is corroded as anode,while the corrosion of copper plate is protected as cathode.All the results revealed that pH and metallographic structure had a significant influence on the corrosion behavior of copper-drawn steel.With the decrease in pH value from 6 to 2.4,the corrosion rate of copper-drawn steel galvanic couple(Cu-Fe GC)obviously increased in the simulated solution of acidic red soil.The electric field formed by the Cu-Fe GC changes the direction of ion migration between the copper and drawn steel electrodes,which impacts the composition and microstructure of corrosion products formed on the electrode surface.展开更多
文摘With the development of science and technology in China, the measuring technique in water resources and hydropower engineering is also developing constantly. Measuring technique in water resources and hydropower engineering is an important link in water conservancy and hydropower projects, which can improve the survey efficiency of water conservancy and hydropower projects and promote the rapid development of China's water conservancy and hydropower projects. This paper will analyze the current situation of measuring technique development of water conservancy and hydropower projects and explore how to improve the measuring efficiency of water conservancy and hydropower projects.
文摘A multi-function sampling system has been set up in Shanghai Ship & Shipping Research Institute (SSSRI) where a test on the fluctuating pressure of two propeller models were carried out. This paper deals with a study on the technical problems concerning the measurement and analysis techniques involved in the test. The sampling and processing procedure of signal is one of the major factors affecting the ac- curacy and stability of the prediction of fluctuating pressure induced by propeller. Integral-peri- od sampling, high enough sampling frequency and suitable resolution must be kept in sampling and processing. The procedure of sampling and processing should be validated by standard signal corresponding to the blade frequency of different orders in comparative tests.
文摘In many situations such as the cores of a rotating electrical machine and the T joints of a multiphase transformer, the local flux density varies with time in terms of both magnitude and direction, i.e. the flux density vector is rotating. Therefore, the magnetic properties of the core materials under the rotating flux density vector excitation should be properly measured, modeled and applied in the design and analysis of these electromagnetic devices. This paper presents an extensive review on the development of techniques and apparatus for measuring the rotational core losses of soft magnetic materials based on the experiences of various researchers in the last hundred years.
基金the National Natural Science Foundation of China(No.31101085)the Scientific Research and Development Foundation for Start-up Projects of Zhejiang Agriculture and Forestry University (No.2034020044)
文摘The purpose of this study is to develop a standard methodology for measuring the surface free energy (SFE),and its component parts of bamboo fiber materials.The current methods was reviewed to determine the surface tension of natural fibers and the disadvantages of techniques used were discussed.Although numerous techniques have been employed to characterize surface tension of natural fibers,it seems that the credibility of results obtained may often be dubious.In this paper,critical surface tension estimates were obtained from computer aided machine vision based measurement.Data were then analyzed by the least squares method to estimate the components of SFE.SFE was estimated by least squares analysis and also by Schultz' method.By using the Fowkes method the polar and disperse fractions of the surface free energy of bamboo fiber materials can be obtained.Strictly speaking,this method is based on a combination of the knowledge of Fowkes theory. SFE is desirable when adhesion is required,and it avoids some of the limitations of existing studies which has been proposed.The calculation steps described in this research are only intended to explain the methods.The results show that the method that only determines SFE as a single parameter may be unable to differentiate adequately between bamboo fiber materials,but it is feasible and very efficient.In order to obtain the maximum performance from the computer aided machine vision based measurement instruments,this measurement should be recommended and kept available for reference.
基金the funding from National Science Fund for Distinguished Young Scholars of the NaturalScience Foundation of China (40225003)the Knowledge Innovation Project of the Chinese Academy of Science(KZCX3-SW-341)
文摘The velocity of blown sand particles is an important parameter in aeolian movement （a special case of gas particle two-phase flow） and has ever been a topic of interest. At present, several techniques have been applied in measuring velocity of the blown sand particles. This paper reviews the measurement results of several commonly used methods： photoelectric cell method, high-speed photographic method, Particle Dynamics Analyzer （PDA） method and Particle Image Velocimetry （PIV） method. Photoelectric cell method, high-speed photograph method and PDA method are useful in studying the velocity distribution of particles. PIV is a whole-flow-field technique and a useful tool to study the average velocity field in a target area. These methods got some similar results but considerable differences also exist. They have come to similar conclusions on the velocity distributions at a single height but direct measurement results with respect to the velocity distribution very close to the surface are still scarce except some PDA results. The magnitude of measured mean particle velocity differs greatly. The relationship obtained by different methods between mean particle velocity and wind velocity, particle size and possibly other influencing factors also differs considerably. Although several authors have proposed similar power functions to describe the variation with height of the mean particle velocity, the predicted results have wide differences. Each technique is based on some unique principles, and has its advantages and disad- vantages. To make full use of different techniques, a lot of work needs be done to validate them. Developing a reliable technique to measure the velocity of blown particles is still a necessary task in aeolian research.
文摘Electrochemical techniques of the corrosion measurements of reinforcing steeI in concrete have been evaluated. These techniques include half-cell potential measurements, impressed voltage method, impressed current method and potentiostatic polarization technique. The results of corrosion behaviour of the steel in both 5%NaCl and 5%MgSO4 show that each electrochemical technique provides some information about the condition of the steel bar or the corrosivity of the environment being evaluated, yet none provides a complete data regarding the corrosion resistance of reinforcing steel in aggressive media
文摘Using the Differential Absorption Lidar (DIAL) technique, two types of approaches, namely, reflection from retroreflector / topographic target and backscatter from atmosphere, are available for studying remotely the atmospheric NO, concentration. The Argon ion lidar system at the Indian Institute of Tropical Meteorology (IITM), Pune, India has been used for the measurements by following both the path-averaged and range-resolved approaches. For the former, a topographic target (hill) is used for determining path-averaged surface concentration. In the latter, spectral properties of atmospheric attenuation is used for making range-resolved measurements in the surface layer. The results of the observations collected by following both approaches are presented. The average surface NO2 concentration was found to vary between 0.01 and 0.105 ppm and the range-resolved measurements exhibited higher values suggesting treatment of the lidar data for scattering and extinction effects due to atmospheric aerosols and air molecules, and atmospheric turbulence. Certain modifications that are suggested to the experimental set-up, data acquisition and analysis to improve the measurements are briefly described.
文摘Recently, optical techniques have attracted great attention due to their excellent non-destructive, non-contact, high-resolution, and full-field characteristics. Applications can be found in diverse fields such as precision mechanics and manufacturing, aerospace and automotive testing and inspection, materials science, and biomedical engineering. Advances in Optical Techniques for Me- chanical Measurements presents the latest research progresses in several widely used optical techniques with applications in preci- sion mechanical engineering.
文摘By using dropped stress creep method a new testing technique for measurement of the fa-tigue-creep interaction resistance is developed. At varied adjusted mean stresses the creep testingwas performed repeatedly When an unlimited extensive incubation period with zero creep rate oc-curred. the stress cavsing zero creep rate is defined as fatigue-creep resistance. The developped test-ing technique was used to measure the fatigue-creep resistance in F anc C regions. The dynamic ef-fective stress could yield a better descrption of fatigue and creep interaction. The fatigue-creep rateequations with varied exponents inF of C region are established. The different deformation mecha-nisms in F or C regions are indicated
基金supported by the National Natural Science Foundation of China under Grant Nos.U2167204,11975040,111 Center(B20065)Brazilian authors were supported in part by local funding agencies CNPq+10 种基金FAPERJCAPESand INCT-FNA(Instituto Nacional de Ciência e Tecnologia,Física Nuclear e Aplicacoes)Research Project No.464898/2014-5Marco Siciliano's work was partially supported by the US Department of EnergyOffice of Scienceand Office of Nuclear Physics(DE-AC02-06CH11357)supported by Nuclear Energy Development and Research Project No.HNKF202224(28)Ling Chuang Research Project of the China National Nuclear Corporation No.CNNCLCKY-2023 and No.20221024000072F6-0002-7Guangdong Key Research and Development Program No.2020B040420005Guangdong Basic and Applied Basic Research Foundation No.2021B1515120027。
文摘The^(6)Li+^(89)Y experiment was performed to explore the reaction mechanism induced by a weakly bound nucleus^(6)Li and its cluster configuration.The particle-γcoincidence method was used to identify the different reaction channels.Theγ-rays coincident with^(3)He/^(3)H indicate that the^(3)H/^(3)He stripping reaction plays a significant role in the formation of Zr/Nb isotopes.The obtained results support the existence of a^(3)He-^(3)H cluster in^(6)Li.Direct and sequential transfer reactions are adequately discussed,and the FRESCO code is used to perform precise finite-range cyclic redundancy check calculations.In the microscopic calculation,direct cluster transfer is more predominant than sequential transfer in^(3)H transfer.However,the direct cluster transfer is of comparable magnitude to the sequential transfer in the^(3)He transfer.
文摘A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted. The tests show that the ignitor and the main charge of the microthruster match well, the dynamic and static capability of the test and measurement meets the test requirement and the result is creditable. The measured technical characteristics of the microthruster are that the ignition delay time is shorter than 0 3?ms, the total impulse is over 3?N·s, the operational time is shorter than 16?ms and the mass ratio of the thruster is 0 216.
文摘Beginning from the origination of the bone-length cun measurement, and proceeding from clinical application, the article differentiated and analyzed 4 measuring methods relate with cun, namely, bone-length cun measurement and finger cun measurement regarding to acupoint locating, cun measurement of filiform needle concerning the size of the body of the needle and cun measurement of acupuncture technique referring to the depth of insertion. It explained different senses of cun in the above 4 measurements. The original meaning and the respective implication for each situation should be clarified. Flexible and proper application is required so as to enhance the therapeutic effect of the treatment and avoid possible accidents.
文摘This study explores the mathematical practices embedded in the cultural traditions of the Tharu community, with a focus on their counting systems, measuring techniques, and modeling patterns. Through ethnographic observations and field interviews, the research reveals how the Tharu people employ a base-20 counting system influenced by the Nepali numbering system and use physical objects for arithmetic operations. Their traditional measuring techniques rely on body-referenced units such as the Haat (hand) and Anguli (finger) for length, along with culturally specific units like the Muthi and Lota for volume. Additionally, the study examines the geometric patterns found in Tharu crafts, highlighting the community’s application of symmetry and ratios. The findings illustrate the significance of these ethnomathematical practices in the daily life of the Tharu people, offering insight into how indigenous mathematical knowledge can enrich the broader understanding of mathematics education. This research contributes to the field of ethnomathematics by documenting and analyzing the ways in which cultural groups integrate mathematical concepts to solve practical problems and preserve their heritage.
文摘A fitting process is used to measure the cavity loss and the quasi Fermi level separation for Fabry Pérot semiconductor lasers.From the amplified spontaneous emission (ASE) spectrum,the gain spectrum and single pass ASE obtained by the Cassidy method are applied in the fitting process.For a 1550nm quantum well InGaAsP ridge waveguide laser,the cavity loss of about ～24cm -1 is obtained.
基金the support of the National Natural Science Foundation of China(Nos.11532014,11727901,11672308 and 11672357)the National Key Research and Development Program of China(No.2019YFA0405204)。
文摘Hypersonic and high-enthalpy wind tunnels and their measurement techniques are the cornerstone of the hypersonic flight era that is a dream for human beings to fly faster,higher and further.The great progress has been achieved during the recent years and their critical technologies are still in an urgent need for further development.There are at least four kinds of hypersonic and high-enthalpy wind tunnels that are widely applied over the world and can be classified according to their operation modes.These wind tunnels are named as air-directly-heated hypersonic wind tunnel,light-gas-heated shock tunnel,free-piston-driven shock tunnel and detonation-driven shock tunnel,respectively.The critical technologies for developing the wind tunnels are introduced in this paper,and their merits and weakness are discussed based on wind tunnel performance evaluation.Measurement techniques especially developed for high-enthalpy flows are a part of the hypersonic wind tunnel technology because the flow is a chemically reacting gas motion and its diagnosis needs specially designed instruments.Three kinds of the measurement techniques considered to be of primary importance are introduced here,including the heat flux sensor,the aerodynamic balance,and optical diagnosis techniques.The techniques are developed usually for conventional wind tunnels,but further improved for hypersonic and high-enthalpy tunnels.The hypersonic ground test facilities have provided us with most of valuable experimental data on high-enthalpy flows and will play a more important role in hypersonic research area in the future.Therefore,several prospects for developing hypersonic and high-enthalpy wind tunnels are presented from our point of view.
基金This work was supported by the National Key R&D program of China(No.2016YFA0400504)by the National Natural Science Foundation of China(Nos.U1832211,U1867210,11922501,11961141004,11575018,11790322,and U1932209).
文摘The LaBr3(Ce)detector has attracted much attention in recent years because of its superior characteristics compared with other scintillating materials in terms of resolution and efficiency.However,it has a relatively high intrinsic background radiation because of the naturally occurring radioisotopes in lanthanum,actinium,and their daughter nuclei.This limits its applications in low-counting rate experiments.In this study,we identified the radioactive isotopes in theφ3"x 3"Saint-Gobain B380 detector by a coincidence measurement using a Clover detector in a low-background shielding system.Moreover,we carried out a Geant4 simulation of the experimental spectra to evaluate the activities of the main internal radiation components.The total activity of the background radiation of B380 is determined to be 1.523(34)Bq/cm^3.The main sources include 138La at 1.428(34)Bq/cm^3,207Tl at 0.0135(13)Bq/cm^3,211Bi at 0.0136(15)Bq/cm^3,215Po at 0.0135(3)Bq/cm^3,219Rn at 0.0125(12)Bq/cm^3,223Fr at 0.0019(11)Bq/cm^3,223Ra at 0.0127(10)Bq/cm^3,227Th at 0.0158(22)Bq/cm^3,and 227Ac at 0.0135(13)Bq/cm^3.Of these,the activities of 207Tl,211Po,215Po,223Fr,and 227Ac are deduced for the first time from the secular equilibrium established in the decay chain of 227Ac.
文摘Inductance-bared electromagnetic tomography (EMT) is a novel industrial process tomographic technique. Exact expressions of the magnetic field distribution in a two-dimensional object space were derived by analytically solving the forward problem for a particular two-component pow. The physical mechanisms within the sensor and the detectability limits of the EMT technique were quantitatively analyzed. Direct mathematical expressions for the field sensitivity and the sensitivity maps were established. To a certain extent, mathematical and theoretical bares are given for quantitative design of the sensor, detectability analysis of the EMT technique and image reconstruction of two-component processes based on the linear back-projection algorithm.
基金Supported by the National Natural Science Foundation of China(20477032)China Agriculture Research System(Nycytx-25)
文摘Cadmium is one of the important contaminative heavy metals. Due to continuous increase of discharge of Cadmium in industrial and agriculture production, cadmium contamination of soil is more and more serious day by day, which seriously threatens ecological environment and human health. Treatment of cadmium becomes an urgent issue and research hot point. At present, remedy for cadmium pollution upon soil mainly are physical restoration, chemical restoration and biological restoration, also there are measurements by means of adding external source matter and selecting low-Cd-accumulation varieties so as to reduce cadmium harm upon agricultural products. This article introduces in detail the resource of cadmium in soil and the present condition of cadmium pollution in farmland and processing of domestic cadmium pollution research, processing stage of domestic and foreign research of restoration of cadmium polluted soil as well as various peculiarities of repair methods. Finally, the expectation of research is discussed.
文摘Quasi-longitudinal waves are one type of structural waves, which are important at high frequencies. This paper studies the estimate theory and measurement technique of quasi-longitudinal waves, analyzes the bias error due to the effect of bending waves. In a two-dimensional quasi-longitudinal wave held, the intensity vector is the sum of the effective intensity vector and the intensity variation vector. Its axial component is proportional to two imaginary parts of cross spectral densities and in the measurement, it is measured by a pair of two-transducer arrays. In a one-dimensional quasi-longitudinal wave field, the intensity variation is zero, the intensity is proportional to only one imaginary part of a cross spectral density and it can be measured using a two-transducer array. If bending and quasi-longitudinal waves coexist and the contribution from bending waves cannot be eliminated or reduced to a certain extent, the measured quasi-longitudinal wave intensity will contain a large error. The results measured on the three-beam structure show that quasi-longitudinal wave intensity can be accurately measured using the intensity technique when bending waves are negligible in comparison with quasi-longitudinal waves.
基金financially supported by the Science and Technology Commission of Shanghai Municipality(No.19DZ2271100)。
文摘The influence of pH and metallographic structure on the corrosion behavior of copper-drawn steel is studied with the simulated system.The effect of pH on the corrosion behavior of copper-drawn steel has been investigated using open-circuit potential,potentiodynamic polarization,galvanic current measurement,scanning electron microscopy and scanning vibrating electrode technique techniques.The steel is corroded as anode,while the corrosion of copper plate is protected as cathode.All the results revealed that pH and metallographic structure had a significant influence on the corrosion behavior of copper-drawn steel.With the decrease in pH value from 6 to 2.4,the corrosion rate of copper-drawn steel galvanic couple(Cu-Fe GC)obviously increased in the simulated solution of acidic red soil.The electric field formed by the Cu-Fe GC changes the direction of ion migration between the copper and drawn steel electrodes,which impacts the composition and microstructure of corrosion products formed on the electrode surface.
