To discuss further the dependence of stochastic resonance on signals, nonlinear systems and noise, especially on noise, the binary input signal buried in Gaussian mixture noise through a nonlinear threshold array is s...To discuss further the dependence of stochastic resonance on signals, nonlinear systems and noise, especially on noise, the binary input signal buried in Gaussian mixture noise through a nonlinear threshold array is studied based on mutual information. It is obtained that Gaussian mixture noise can improve the information transmission through the array. Both stochastic resonance （SR） and suprathreshold stochastic resonance （SSR） can be observed in the single threshold system and in the threshold array. The parameters in noise distribution affect the occurrence of SR and SSR. The efficacy of information transmission can be significantly enhanced as the number of threshold devices in the array increases. These results show further the dependence of SR and SSR on the noise distribution, and also extend the applicability of SR and SSR in information transmission.展开更多
A novel magnetic-controlled switcher type fault current limiter (FCL) based on the topology of the saturated iron core high temperature superconducting FCL is proposed. The magnetic field distribution of the FCL iron ...A novel magnetic-controlled switcher type fault current limiter (FCL) based on the topology of the saturated iron core high temperature superconducting FCL is proposed. The magnetic field distribution of the FCL iron core is analyzed by FEA software ANSYS. The current limiting characteristic is investigated by both 3-D field-circuit coupled simulation and Matlab. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively,and the FCL has the advantages of simple and reliable structure, flexible control strategy. The simulation and experimental results prove that the theoretical expectation and current limiting performance is satisfactory for practical use.展开更多
To achieve sparse sampling on a coded ultrasonic signal,the finite rate of innovation(FRI)sparse sampling technique is proposed on a binary frequency-coded(BFC)ultrasonic signal.A framework of FRI-based sparse samplin...To achieve sparse sampling on a coded ultrasonic signal,the finite rate of innovation(FRI)sparse sampling technique is proposed on a binary frequency-coded(BFC)ultrasonic signal.A framework of FRI-based sparse sampling for an ultrasonic signal pulse is presented.Differences between the pulse and the coded ultrasonic signal are analyzed,and a response mathematical model of the coded ultrasonic signal is established.A time-domain transform algorithm,called the high-order moment method,is applied to obtain a pulse stream signal to assist BFC ultrasonic signal sparse sampling.A sampling of the output signal with a uniform interval is then performed after modulating the pulse stream signal by a sampling kernel.FRI-based sparse sampling is performed using a self-made circuit on an aluminum alloy sample.Experimental results show that the sampling rate reduces to 0.5 MHz,which is at least 12.8 MHz in the Nyquist sampling mode.The echo peak amplitude and the time of flight are estimated from the sparse sampling data with maximum errors of 9.324%and 0.031%,respectively.This research can provide a theoretical basis and practical application reference for reducing the sampling rate and data volume in coded ultrasonic testing.展开更多
Biological ion channels show that ultrafast ions and molecules transmission are in a quantum way of single molecular or ionic chain with a certain number of molecules or ions, and we define it as ＂quantum-confined su...Biological ion channels show that ultrafast ions and molecules transmission are in a quantum way of single molecular or ionic chain with a certain number of molecules or ions, and we define it as ＂quantum-confined superfluid＂ （QSF）. This ordered ultrafast flow in the confined channel can be considered as ＂quantum tunneling fluid effect＂ with a ＂tunneling distance＂, which is corresponding to the period of QSF. Recent research demonstrated that artificial biomimetic nanochannels also showed the phenomenon of QSF, such as ion and water channels. The introduction of QSF concept in the fields of chemistry and biology may create significant impact. As for chemistry, the QSF effect provides new ideas for accurate synthesis in organic, inorganic, polymer, etc. We believe the implementation of the idea of QSF will promote the development of QSF biochemistry, biophysics, bioinformatics and biomedical science.展开更多
The tradeoff between sensitivity and detection range(maximum and minimum stretchability)is a key limitation in strain sensors;to resolve this,we develop an efficient and novel strategy herein to fabricate a highly sen...The tradeoff between sensitivity and detection range(maximum and minimum stretchability)is a key limitation in strain sensors;to resolve this,we develop an efficient and novel strategy herein to fabricate a highly sensitive and stretchable strain sensor inspired by the membrane-shell structure of poultry eggs.The developed sensor comprises a soft and stretchable surface-grafting polypyrrole(s-PPy)film(acting as the membrane)and a brittle Au film(acting as the shell),wherein both films complement each other at the electrical and mechanical levels.Au forms cracks under strain contributing to its high sensitivity and low detection limit,and s-PPy can bridge Au cracks and increase stretchability which has not been used in strain sensors before.The surface-grafting strategy not only enhances interface adhesion but also tunes the brittle property of native PPy to render it stretchable.Utilizing the synergetic effect of the membrane-shell complementary structure,the strain sensors achieve ultrahigh sensitivity(>10^(7)),large stretchability(100%),and an ultralow detection limit(0.1%),demonstrating significant progress in the field of strain sensors.The membrane-shell(Au/s-PPy)-structured strain sensor can successfully detect finger motion,wrist rotation,airflow fluctuation,and voice vibration;these movements produce strain in the range of subtle to marked deformations.Results evidence the ultrahigh performance and bright application prospects of the developed strain sensors.展开更多
Stimulated emission depletion(STED) microscope is one of the most prominent super-resolution bio-imaging instruments, which holds great promise for ultrahigh-resolution imaging of cells. To construct a STED microscope...Stimulated emission depletion(STED) microscope is one of the most prominent super-resolution bio-imaging instruments, which holds great promise for ultrahigh-resolution imaging of cells. To construct a STED microscope, it is challenging to realize temporal synchronization between the excitation pulses and the depletion pulses. In this study, we present a simple and low-cost method to achieve pulse synchronization by using a condensed fluorescent dye as a depletion indicator. By using this method, almost all the confocal microscopes can be upgraded to a STED system without losing its original functions. After the pulse synchronization,our STED system achieved sub-100-nm resolution for fluorescent nanospheres and single-cell imaging.展开更多
文摘To discuss further the dependence of stochastic resonance on signals, nonlinear systems and noise, especially on noise, the binary input signal buried in Gaussian mixture noise through a nonlinear threshold array is studied based on mutual information. It is obtained that Gaussian mixture noise can improve the information transmission through the array. Both stochastic resonance （SR） and suprathreshold stochastic resonance （SSR） can be observed in the single threshold system and in the threshold array. The parameters in noise distribution affect the occurrence of SR and SSR. The efficacy of information transmission can be significantly enhanced as the number of threshold devices in the array increases. These results show further the dependence of SR and SSR on the noise distribution, and also extend the applicability of SR and SSR in information transmission.
基金Major State Basic Research Development Program of China ( No.2005CB221505)Research Foundation for the Doctoral Programof Higher Education of China(No.20050248058)
文摘A novel magnetic-controlled switcher type fault current limiter (FCL) based on the topology of the saturated iron core high temperature superconducting FCL is proposed. The magnetic field distribution of the FCL iron core is analyzed by FEA software ANSYS. The current limiting characteristic is investigated by both 3-D field-circuit coupled simulation and Matlab. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively,and the FCL has the advantages of simple and reliable structure, flexible control strategy. The simulation and experimental results prove that the theoretical expectation and current limiting performance is satisfactory for practical use.
基金The National Natural Science Foundation of China (No.51375217)。
文摘To achieve sparse sampling on a coded ultrasonic signal,the finite rate of innovation(FRI)sparse sampling technique is proposed on a binary frequency-coded(BFC)ultrasonic signal.A framework of FRI-based sparse sampling for an ultrasonic signal pulse is presented.Differences between the pulse and the coded ultrasonic signal are analyzed,and a response mathematical model of the coded ultrasonic signal is established.A time-domain transform algorithm,called the high-order moment method,is applied to obtain a pulse stream signal to assist BFC ultrasonic signal sparse sampling.A sampling of the output signal with a uniform interval is then performed after modulating the pulse stream signal by a sampling kernel.FRI-based sparse sampling is performed using a self-made circuit on an aluminum alloy sample.Experimental results show that the sampling rate reduces to 0.5 MHz,which is at least 12.8 MHz in the Nyquist sampling mode.The echo peak amplitude and the time of flight are estimated from the sparse sampling data with maximum errors of 9.324%and 0.031%,respectively.This research can provide a theoretical basis and practical application reference for reducing the sampling rate and data volume in coded ultrasonic testing.
基金supported by the National Key R&D Program of China(2017YFA0206900)the National Natural Science Foundation of China(21625303)
文摘Biological ion channels show that ultrafast ions and molecules transmission are in a quantum way of single molecular or ionic chain with a certain number of molecules or ions, and we define it as ＂quantum-confined superfluid＂ （QSF）. This ordered ultrafast flow in the confined channel can be considered as ＂quantum tunneling fluid effect＂ with a ＂tunneling distance＂, which is corresponding to the period of QSF. Recent research demonstrated that artificial biomimetic nanochannels also showed the phenomenon of QSF, such as ion and water channels. The introduction of QSF concept in the fields of chemistry and biology may create significant impact. As for chemistry, the QSF effect provides new ideas for accurate synthesis in organic, inorganic, polymer, etc. We believe the implementation of the idea of QSF will promote the development of QSF biochemistry, biophysics, bioinformatics and biomedical science.
基金the National Key Research and Development Program(2018YFA0703200 and2016YFB0401100)the National Natural Science Foundation of China(21573277,51503221 and 21905199)+1 种基金Tianjin Natural Science Foundation(19JCJQJC62600 and 194214030036)the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(QYZDB-SSW-SLH031)。
文摘The tradeoff between sensitivity and detection range(maximum and minimum stretchability)is a key limitation in strain sensors;to resolve this,we develop an efficient and novel strategy herein to fabricate a highly sensitive and stretchable strain sensor inspired by the membrane-shell structure of poultry eggs.The developed sensor comprises a soft and stretchable surface-grafting polypyrrole(s-PPy)film(acting as the membrane)and a brittle Au film(acting as the shell),wherein both films complement each other at the electrical and mechanical levels.Au forms cracks under strain contributing to its high sensitivity and low detection limit,and s-PPy can bridge Au cracks and increase stretchability which has not been used in strain sensors before.The surface-grafting strategy not only enhances interface adhesion but also tunes the brittle property of native PPy to render it stretchable.Utilizing the synergetic effect of the membrane-shell complementary structure,the strain sensors achieve ultrahigh sensitivity(>10^(7)),large stretchability(100%),and an ultralow detection limit(0.1%),demonstrating significant progress in the field of strain sensors.The membrane-shell(Au/s-PPy)-structured strain sensor can successfully detect finger motion,wrist rotation,airflow fluctuation,and voice vibration;these movements produce strain in the range of subtle to marked deformations.Results evidence the ultrahigh performance and bright application prospects of the developed strain sensors.
基金supported by the National Natural Science Foundation of China (21227804, 21390414, 61378062, 21505148)National Key Research and Development Program (2016YFA0400902)the Natural Science Foundation of Shanghai (15ZR1448400, 14ZR1448000)
文摘Stimulated emission depletion(STED) microscope is one of the most prominent super-resolution bio-imaging instruments, which holds great promise for ultrahigh-resolution imaging of cells. To construct a STED microscope, it is challenging to realize temporal synchronization between the excitation pulses and the depletion pulses. In this study, we present a simple and low-cost method to achieve pulse synchronization by using a condensed fluorescent dye as a depletion indicator. By using this method, almost all the confocal microscopes can be upgraded to a STED system without losing its original functions. After the pulse synchronization,our STED system achieved sub-100-nm resolution for fluorescent nanospheres and single-cell imaging.
