A shape measurement based on ESPI by using carrier is presented. When the tested object is tilted with a small angle,the carrier pattern containing altitude information is formed on the object surface. By using the ca...A shape measurement based on ESPI by using carrier is presented. When the tested object is tilted with a small angle,the carrier pattern containing altitude information is formed on the object surface. By using the carrier pattern captured by a CCD camera,the phase of the object can be derived by Fourier transform and the shape measurement is realized. The principle of the method is introduced and proved by an experiment.展开更多
As one of the interesting optical techniques for measurements of the velocity,the spatial filtering method is treated briefly in this paper.We shown theoretical analysis and calculation of spatial filtering velocimetr...As one of the interesting optical techniques for measurements of the velocity,the spatial filtering method is treated briefly in this paper.We shown theoretical analysis and calculation of spatial filtering velocimetry,and discussed two-dimensional measurements of the velocity.About the data processing,we used A/D conversion and interfaced with a microcomputer,so that the data can be processed automatically by the microcomputer.The preliminary experiment was performed and the experimental results show the usefulness of the present method for measurements of the velocity.展开更多
With more scaling, the speed of than 40 years Moore CMOS transistors is around 100 GHz. Such fact makes it possible to realize mm-wave circuits in CMOS. However, with the target of achieving broadband and power-effici...With more scaling, the speed of than 40 years Moore CMOS transistors is around 100 GHz. Such fact makes it possible to realize mm-wave circuits in CMOS. However, with the target of achieving broadband and power-efficient operation, 60 GHz CMOS RF transceiver faces severe challenges. After reviewing the technology issues, regarding the 60 GHz applications, this paper discusses design challenges both from the system and the building block levels, and also presents some simulated or measured circuits results.展开更多
Shannon entropy in time domain is a measure of signal or system uncertainty.When based on spectrum entropy,Shannon entropy can be taken as a measure of signal or system complexity. Therefore,wavelet analysis based on ...Shannon entropy in time domain is a measure of signal or system uncertainty.When based on spectrum entropy,Shannon entropy can be taken as a measure of signal or system complexity. Therefore,wavelet analysis based on wavelet entropy measure can signify the complexity of non-steady signal or system in both time and frequency domain.In this paper,in order to meet the requirements of post-analysis on abundant wavelet transform result data and the need of information mergence,the basic definition of wavelet entropy measure is proposed,corresponding algorithms of several wavelet entropies,such as wavelet average entropy,wavelet time-frequency entropy,wavelet distance entropy, etc.are put forward,and the physical meanings of these entropies are analyzed as well.The application principle of wavelet entropy measure in ElectroEncephaloGraphy (EEG) signal analysis,mechanical fault diagnosis,fault detection and classification in power system are analyzed.Finally,take the transmission line fault detection in power system for example,simulations in two different systems,a 10kV automatic blocking and continuous power transmission line and a 500kV Extra High Voltage (EHV) transmission line,are carried out,and the two methods,wavelet entropy and wavelet modulus maxima,are compared,the results show feasibility and application prospect of the six wavelet entro- pies.展开更多
Since the CPU of embed system has some limitation in operating speed, a new filter was put forward which implemented mountain template convolution by performing rectangle template convolution two times. It can obtain ...Since the CPU of embed system has some limitation in operating speed, a new filter was put forward which implemented mountain template convolution by performing rectangle template convolution two times. It can obtain time and frequency localization with computational complexity greatly reduced. This algorithm was applied to lightning waveforms (include chopped waveforms) parameter calculation. It simplifies the computation and the results pretreated by this algorithm are in accord with IEC1083-2 completely. It was applied in embed system successfully. Its capability in frequency restraining was researched. The validity of the algorithm was proved in theory when processing lightning waves. The standard sources and the processing results are consistent completely.展开更多
The rotatory optics element in the tensor dielectric coefficient matrix is an important para-(meter) for analyzing and calculating a rotatory optical fiber by electromagnetic theory. But the mea-(surement) of rotatory...The rotatory optics element in the tensor dielectric coefficient matrix is an important para-(meter) for analyzing and calculating a rotatory optical fiber by electromagnetic theory. But the mea-(surement) of rotatory optics element is difficult for the rotatory optical fiber. A simple principle and method for measuring rotatory optics element are put forward in this paper. Firstly by using electromagnetic theory it was demonstrated that the rotatory optics element has a simple linear relation with the rotatory angle, and then the rotatory optics element has a simple linear relation with the magnetic field strength (or bias current in the helix coil) . Secondly a measurement system for the rotatory optics element in the rotatory optical fiber was designed. Using the measurement system the rotatory element can be obtained by measuring the bias current simply.展开更多
The electro-optic properties of a poled second-order nonlinear optical maleimide polymer system were reported.This polymer was synthesized by doping disperse red 1 moieties into the maleimide system as the side chains...The electro-optic properties of a poled second-order nonlinear optical maleimide polymer system were reported.This polymer was synthesized by doping disperse red 1 moieties into the maleimide system as the side chains.Its glass transition temperature was measured to be 202 ℃ by Differential Scanning Calorimetry (DSC) technology.After being poled,the measured electro-optic coefficient of PHSD at the wavelength of 1 550 nm is as large as 3.03 pm/v.Except for an initial decay after being poled,PHSD exhibits little electro-optic relaxation in a long term and its electro-optic coefficient remains about 2.46 pm/v after 15 days.展开更多
Measurements of gamma radiation （200 keV to 10 MeV） were performed between May 25 to September 30 2016 at ITA （Technological Institute of Aeronautics） in Sao Jose dos Campos, SP, Brazil. Detector and associated el...Measurements of gamma radiation （200 keV to 10 MeV） were performed between May 25 to September 30 2016 at ITA （Technological Institute of Aeronautics） in Sao Jose dos Campos, SP, Brazil. Detector and associated electronics were previously calibrated in the laboratory of ITA using radioactive sources Cs-137, Po-210 and Sr-90. These sources provide gamma-ray energies in 0.662 keV alpha particles of 5.4 MeV and 0.90 keV electrons, respectively. Detector is a scintillator Sodium Iodide activated with Thallium [NaI（Tl）] associated to a photomultiplier and electronic devices which gather, store, distribute and structure data so users can analyze them. During the period of May-September, the experimental set was installed in an open room on a tower 25 meters above the ground. Measurements indicated variations of ionizing radiation in function of dry weather, rain, cold fronts passes and presence of fog in the area; the sample time interval was minute by minute. This study discusses the analysis and the dynamics of how to measure meteorological parameters using an ionizing radiation system.展开更多
A Lithium niobate （LiNbO3） based integrated optical E-field sensor with an optical waveguide Mach-Zehnder interferometer （MZI） and a tapered antenna has been designed and fabricated for the measurement of the puls...A Lithium niobate （LiNbO3） based integrated optical E-field sensor with an optical waveguide Mach-Zehnder interferometer （MZI） and a tapered antenna has been designed and fabricated for the measurement of the pulsed electric field. The minimum detectable E-field of the sensor was 10kV/m. The sensor showed a good linear characteristic while the input E-fields varied from 10kV/m to 370kV/m. Furthermore, the maximum detectable E-field of the sensor, which could be calculated from the sensor input/output characteristic, was approximately equal to 1000kV/m. All these results suggest that such sensor can be used for the measurement of the lighting impulse electric field.展开更多
In this paper, we focus on ionospheric absorption in the East Asia sector, and look for manifestations of atmospheric influences in this area. First, a 4-year historical record of absorption measurement at Beijing is ...In this paper, we focus on ionospheric absorption in the East Asia sector, and look for manifestations of atmospheric influences in this area. First, a 4-year historical record of absorption measurement at Beijing is presented. This record was obtained by a sweep frequency technique, in which 27-days periodic variation of the absorption level was found to be dominant, appearing in most seasons except winters. Instead, unusual enhancements of the absorption level appeared in winters (winter anomaly), at the meantime the level varied with periods mainly in the range of 8-12 days. Comparing to 27-days period from the Sun, the shorter period oscillations should be related to planetary wave activities in lower atmosphere. Second, fmin data from 5 mid-latitude ionosondes in Japan were used as an indirect but long-term measurement. With the fmin data covering two solar cycles, disturbances with various periods were found to be active around solar maximum years, but the 8-12 days oscillations always existed in winter, showing seasonal dependence instead of connection to solar activity. These results given in this paper demonstrate seasonal and solar cycle-dependent features of the ionospheric absorption in East Asia sector, and confirm the existence of influence from atmosphere-ionosphere coupling in this area, as well as the relationship between ionospheric winter anomaly and planetary wave activity.展开更多
High-precision sensing of vectorial forces has broad impact on both fundamental research and technological applications such as the examination of vacuum fluctuations and the detection of surface roughness of nanostru...High-precision sensing of vectorial forces has broad impact on both fundamental research and technological applications such as the examination of vacuum fluctuations and the detection of surface roughness of nanostructures.Recent years have witnessed much progress on sensing alternating electromagnetic forces for the rapidly advancing quantum technology-orders of magnitude improvement has been accomplished on the detection sensitivity with atomic sensors,whereas such high-precision measurements for static electromagnetic forces have rarely been demonstrated.Here,based on quantum atomic matter waves confined by a two-dimensional optical lattice,we perform precision measurement of static electromagnetic forces by imaging coherent wave mechanics in the reciprocal space.The lattice confinement causes a decoupling between real-space and reciprocal dynamics,and provides a rigid coordinate frame for calibrating the wavevector accumulation of the matter wave.With that we achieve a stateof-the-art sensitivity of 2.30(8)×10^(-26) N/√Hz.Long-term stabilities on the order of 10^(-28) N are observed in the two spatial components of a force,which allows probing atomic Van der Waals forces at one millimeter distance.As a further illustrative application,we use our atomic sensor to calibrate the control precision of an alternating electromagnetic force applied in the experiment.Future developments of this method hold promise for delivering unprecedented atom-based quantum force sensing technologies.展开更多
文摘A shape measurement based on ESPI by using carrier is presented. When the tested object is tilted with a small angle,the carrier pattern containing altitude information is formed on the object surface. By using the carrier pattern captured by a CCD camera,the phase of the object can be derived by Fourier transform and the shape measurement is realized. The principle of the method is introduced and proved by an experiment.
文摘As one of the interesting optical techniques for measurements of the velocity,the spatial filtering method is treated briefly in this paper.We shown theoretical analysis and calculation of spatial filtering velocimetry,and discussed two-dimensional measurements of the velocity.About the data processing,we used A/D conversion and interfaced with a microcomputer,so that the data can be processed automatically by the microcomputer.The preliminary experiment was performed and the experimental results show the usefulness of the present method for measurements of the velocity.
基金the Project'Design of 60GHz RF CMOS chips and modules'supported by Chinese National High Tech.(863)Plan(2011AA010201 and 2011AA010202)partly supported by National Natural Science Foundation of China(No.61306030)
文摘With more scaling, the speed of than 40 years Moore CMOS transistors is around 100 GHz. Such fact makes it possible to realize mm-wave circuits in CMOS. However, with the target of achieving broadband and power-efficient operation, 60 GHz CMOS RF transceiver faces severe challenges. After reviewing the technology issues, regarding the 60 GHz applications, this paper discusses design challenges both from the system and the building block levels, and also presents some simulated or measured circuits results.
基金Supported by the National Natural Science Foundation of China (No.50407009)Distinguished Scholars Foundation of Sichuan Province (No.06ZQ026-012)Science Fund of Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control,Ministry of Education,China (No.KW02002).
文摘Shannon entropy in time domain is a measure of signal or system uncertainty.When based on spectrum entropy,Shannon entropy can be taken as a measure of signal or system complexity. Therefore,wavelet analysis based on wavelet entropy measure can signify the complexity of non-steady signal or system in both time and frequency domain.In this paper,in order to meet the requirements of post-analysis on abundant wavelet transform result data and the need of information mergence,the basic definition of wavelet entropy measure is proposed,corresponding algorithms of several wavelet entropies,such as wavelet average entropy,wavelet time-frequency entropy,wavelet distance entropy, etc.are put forward,and the physical meanings of these entropies are analyzed as well.The application principle of wavelet entropy measure in ElectroEncephaloGraphy (EEG) signal analysis,mechanical fault diagnosis,fault detection and classification in power system are analyzed.Finally,take the transmission line fault detection in power system for example,simulations in two different systems,a 10kV automatic blocking and continuous power transmission line and a 500kV Extra High Voltage (EHV) transmission line,are carried out,and the two methods,wavelet entropy and wavelet modulus maxima,are compared,the results show feasibility and application prospect of the six wavelet entro- pies.
文摘Since the CPU of embed system has some limitation in operating speed, a new filter was put forward which implemented mountain template convolution by performing rectangle template convolution two times. It can obtain time and frequency localization with computational complexity greatly reduced. This algorithm was applied to lightning waveforms (include chopped waveforms) parameter calculation. It simplifies the computation and the results pretreated by this algorithm are in accord with IEC1083-2 completely. It was applied in embed system successfully. Its capability in frequency restraining was researched. The validity of the algorithm was proved in theory when processing lightning waves. The standard sources and the processing results are consistent completely.
文摘The rotatory optics element in the tensor dielectric coefficient matrix is an important para-(meter) for analyzing and calculating a rotatory optical fiber by electromagnetic theory. But the mea-(surement) of rotatory optics element is difficult for the rotatory optical fiber. A simple principle and method for measuring rotatory optics element are put forward in this paper. Firstly by using electromagnetic theory it was demonstrated that the rotatory optics element has a simple linear relation with the rotatory angle, and then the rotatory optics element has a simple linear relation with the magnetic field strength (or bias current in the helix coil) . Secondly a measurement system for the rotatory optics element in the rotatory optical fiber was designed. Using the measurement system the rotatory element can be obtained by measuring the bias current simply.
基金This work is partially supported by National Natural ScienceFoundation of China ( Grant No:60377013 ,60507013) WHUT Foundation(XJJ2005175) .
文摘The electro-optic properties of a poled second-order nonlinear optical maleimide polymer system were reported.This polymer was synthesized by doping disperse red 1 moieties into the maleimide system as the side chains.Its glass transition temperature was measured to be 202 ℃ by Differential Scanning Calorimetry (DSC) technology.After being poled,the measured electro-optic coefficient of PHSD at the wavelength of 1 550 nm is as large as 3.03 pm/v.Except for an initial decay after being poled,PHSD exhibits little electro-optic relaxation in a long term and its electro-optic coefficient remains about 2.46 pm/v after 15 days.
文摘Measurements of gamma radiation （200 keV to 10 MeV） were performed between May 25 to September 30 2016 at ITA （Technological Institute of Aeronautics） in Sao Jose dos Campos, SP, Brazil. Detector and associated electronics were previously calibrated in the laboratory of ITA using radioactive sources Cs-137, Po-210 and Sr-90. These sources provide gamma-ray energies in 0.662 keV alpha particles of 5.4 MeV and 0.90 keV electrons, respectively. Detector is a scintillator Sodium Iodide activated with Thallium [NaI（Tl）] associated to a photomultiplier and electronic devices which gather, store, distribute and structure data so users can analyze them. During the period of May-September, the experimental set was installed in an open room on a tower 25 meters above the ground. Measurements indicated variations of ionizing radiation in function of dry weather, rain, cold fronts passes and presence of fog in the area; the sample time interval was minute by minute. This study discusses the analysis and the dynamics of how to measure meteorological parameters using an ionizing radiation system.
文摘A Lithium niobate （LiNbO3） based integrated optical E-field sensor with an optical waveguide Mach-Zehnder interferometer （MZI） and a tapered antenna has been designed and fabricated for the measurement of the pulsed electric field. The minimum detectable E-field of the sensor was 10kV/m. The sensor showed a good linear characteristic while the input E-fields varied from 10kV/m to 370kV/m. Furthermore, the maximum detectable E-field of the sensor, which could be calculated from the sensor input/output characteristic, was approximately equal to 1000kV/m. All these results suggest that such sensor can be used for the measurement of the lighting impulse electric field.
基金supported by the National Natural Science Foundation of China (Grant No. 40904036)the Public Science and Technology Research Funds Projects of Ocean, State Oceanic Administration of China (Grant No. 201005017)+1 种基金the National Basic Research Program of China ("973" Project) (Grant No. 2011CB811405)the Specialized Research Fund for State Key Laboratories
文摘In this paper, we focus on ionospheric absorption in the East Asia sector, and look for manifestations of atmospheric influences in this area. First, a 4-year historical record of absorption measurement at Beijing is presented. This record was obtained by a sweep frequency technique, in which 27-days periodic variation of the absorption level was found to be dominant, appearing in most seasons except winters. Instead, unusual enhancements of the absorption level appeared in winters (winter anomaly), at the meantime the level varied with periods mainly in the range of 8-12 days. Comparing to 27-days period from the Sun, the shorter period oscillations should be related to planetary wave activities in lower atmosphere. Second, fmin data from 5 mid-latitude ionosondes in Japan were used as an indirect but long-term measurement. With the fmin data covering two solar cycles, disturbances with various periods were found to be active around solar maximum years, but the 8-12 days oscillations always existed in winter, showing seasonal dependence instead of connection to solar activity. These results given in this paper demonstrate seasonal and solar cycle-dependent features of the ionospheric absorption in East Asia sector, and confirm the existence of influence from atmosphere-ionosphere coupling in this area, as well as the relationship between ionospheric winter anomaly and planetary wave activity.
基金supported by the National Program on Key Basic Research Project of China (2018YFA0305601, 2021YFA07183012021YFA1400900)+4 种基金the National Natural Science Foundation of China (61727819, 11934002, and 11874073)Shanghai Municipal Science and Technology Major Project (2019SHZDZCX01)the Chinese Academy of Sciences Priority Research Program(XDB35020100)the Science and Technology Major Project of Shanxi (202101030201022)the Space Application System of China Manned Space Program
文摘High-precision sensing of vectorial forces has broad impact on both fundamental research and technological applications such as the examination of vacuum fluctuations and the detection of surface roughness of nanostructures.Recent years have witnessed much progress on sensing alternating electromagnetic forces for the rapidly advancing quantum technology-orders of magnitude improvement has been accomplished on the detection sensitivity with atomic sensors,whereas such high-precision measurements for static electromagnetic forces have rarely been demonstrated.Here,based on quantum atomic matter waves confined by a two-dimensional optical lattice,we perform precision measurement of static electromagnetic forces by imaging coherent wave mechanics in the reciprocal space.The lattice confinement causes a decoupling between real-space and reciprocal dynamics,and provides a rigid coordinate frame for calibrating the wavevector accumulation of the matter wave.With that we achieve a stateof-the-art sensitivity of 2.30(8)×10^(-26) N/√Hz.Long-term stabilities on the order of 10^(-28) N are observed in the two spatial components of a force,which allows probing atomic Van der Waals forces at one millimeter distance.As a further illustrative application,we use our atomic sensor to calibrate the control precision of an alternating electromagnetic force applied in the experiment.Future developments of this method hold promise for delivering unprecedented atom-based quantum force sensing technologies.
