A small-signal equivalent circuit model and the ted. The equivalent lumped circuit, which takes the main extraction techniques for photodetector chips are presen- factors that limit a photodetector＇s RF performance i...A small-signal equivalent circuit model and the ted. The equivalent lumped circuit, which takes the main extraction techniques for photodetector chips are presen- factors that limit a photodetector＇s RF performance into consideration,is first determined based on the device＇s physical structure. The photodetector＇s S parameters are then on-wafer measured, and the measured raw data are processed with further calibration. A genetic algorithm is used to fit the measured data, thereby allowing us to calculate each parameter value of the model. Experimental resuits show that the modeled parameters are well matched to the measurements in a frequency range from 130MHz to 20GHz, and the proposed method is proved feasible. This model can give an exact description of the photodetector chip＇s high frequency performance,which enables an effective circuit-level prediction for photodetector and optoelectronic integrated circuits.展开更多
A 0. 5mV high sensitivity,200Mbps CMOS limiting amplifier （LA） with 72dB ultra wide dynamic range is described. A novel active DC offset cancellation loop is elaborately analyzed and designed to achieve this perform...A 0. 5mV high sensitivity,200Mbps CMOS limiting amplifier （LA） with 72dB ultra wide dynamic range is described. A novel active DC offset cancellation loop is elaborately analyzed and designed to achieve this performance. Using a signal path, a received signal strength indicator （RSSI）, based on the piecewise-linear approximation, is realized with a ± 2dB logarithmic accuracy in a 60dB indicating range. The architecture of the LA and RSSI employed is determined by the optimal sensitivity and RSSI accuracy for a specified speed, gain, and power consumption. It consumes 60mW from a single 5V supply. The active area is 1.05mm^2 using standard 5V 0.6μm CMOS technology.展开更多
The transmission delay of photogenerated carriers in a CMOS-process-compatible double photodiode (DPD) is analyzed by using device simulation.The DPD small signal equivalent circuit model which includes transmission d...The transmission delay of photogenerated carriers in a CMOS-process-compatible double photodiode (DPD) is analyzed by using device simulation.The DPD small signal equivalent circuit model which includes transmission delay of photogenerated carriers is given.From analysis on the frequency domain of the circuit model the device has two poles.One has the relationship with junction capacitance and the DPD’s load,the other with the depth and the doping concentration of the N-well in the DPD.Different depth of the N-well and different area of the DPDs with bandwidth were compared.The analysis results are important to design the high speed DPDs.展开更多
Proposes an H_∞ deconvolution design for time-delay linear continuous-time systems. We first analyze the general structure and innovation structure of the H_∞ deconvolution filter. The deconvolution filter with inno...Proposes an H_∞ deconvolution design for time-delay linear continuous-time systems. We first analyze the general structure and innovation structure of the H_∞ deconvolution filter. The deconvolution filter with innovation structure is made up of an output observer and a linear mapping, where the latter reflects the internal connection between the unknown input signal and the output estimate error. Based on the bounded real lemma, a time domain design approach and a sufficient condition for the existence of deconvolution filter are presented. The parameterization of the deconvolution filter can be completed by solving a Riccati equation. The proposed method is useful for the case that does not require statistical information about disturbances. At last, a numerical example is given to demonstrate the performance of the proposed filter.展开更多
A new method of phase spectral analysis of EEG is proposed for the comparative analysis of phase spectra between normal EEG and epileptic EEG signals based on the wavelet decomposition technique. By using multiscale w...A new method of phase spectral analysis of EEG is proposed for the comparative analysis of phase spectra between normal EEG and epileptic EEG signals based on the wavelet decomposition technique. By using multiscale wavelet decomposition,the original EEGs are mapped to an orthogonal wavelet space,such that the variations of phase can be observed at multiscale. It is found that the phase (and phase difference) spectra of normal EEGs are distinct from that of epileptic EEGs. That is the variations of phase (and phase difference) of normal EEGs have a distinct periodic pattern with the electrical activity proceeds in the brain,but do not the epileptic EEGs. For epileptic EEGs,only at those transient points,the phase variations are obvious. In order to verify these results with the observational data,the phase variations of EEGs in principal component space are observed and found that,the features of phase spectra is in correspondence with that the wavelet space. These results make it possible to view the behavior of EEG rhythms as a dynamic spectrum.展开更多
The stronglink with muhi-try function based on MEMS technology and the PC startup in authentication system have been designed and fabricated. The generation principle and structure of UQS code are introduced, which co...The stronglink with muhi-try function based on MEMS technology and the PC startup in authentication system have been designed and fabricated. The generation principle and structure of UQS code are introduced, which consists of two groups of metal counter-meshing gears, two pawl/ratchet mechanisms, two driving micromotors and two resetting micromotors. The energy-coupling element is a photoelectric sensor with a circular and notched plate. It is fabricated using the UV-LiGA process and precision mechanical engineering. The PC startup authentication system is controlled by BIOS program, which is written into the chip according with special format. The program in BIOS output signals controls the running of stronglink to finish the process of authentication. The device can run more than 10000 times before a stop. The driving voltage is 12 V, and the normal decoding time is 3 s.展开更多
This paper describes relatively simple stochastic model of the total ground irradiance of horizontal surface. For this purpose clearness index is modeled as a stochastic signal. The parameters of clearness index stoch...This paper describes relatively simple stochastic model of the total ground irradiance of horizontal surface. For this purpose clearness index is modeled as a stochastic signal. The parameters of clearness index stochastic signal are chosen to fit values of daily mean insolation for each month for the location of Zagreb, Croatia. Complete model has been done in MATLAB. This model can be used for Monte Carlo simulations of technical solar systems such as photovoltaic systems or solar thermal energy systems.展开更多
In order to improve the test accuracy of CCD,a new type of CCD device is proposed.Several columns(rows) of photoelectric diodes(PDs) are combined together,and staggered with the distance of H1=H/N,where H is the space...In order to improve the test accuracy of CCD,a new type of CCD device is proposed.Several columns(rows) of photoelectric diodes(PDs) are combined together,and staggered with the distance of H1=H/N,where H is the space between two adjacent PDs,and N is the number of columns(rows).The photoelectric signals are collected simultaneously by multi-channel A/D,and the accurate measurement result is obtained through appropriate signal processing.Without changing the size or space of PDs,more photographic pixels are arranged in the given direction within a finite length.Diameters of three standard poles are measured by a single CCD and two staggered CCDs,respectively with length of 30 mm and diameters of 5 mm,8 mm and 12 mm,respectively.The results show that the accuracy of double staggered CCDs is two times of that of single CCD.The new type of CCDs can avoid the impact of PD space theoretically and higher measurement accuracy can be obtained.展开更多
In this work, a double signal amplified immunosen- sor based on the enhanced CdSe@ZnS quantum dots （QDs） electrochemiluminescence （ECL） via TiO2 nanoparticles （TiO2 NPs） and the outstanding quencher of polydopam...In this work, a double signal amplified immunosen- sor based on the enhanced CdSe@ZnS quantum dots （QDs） electrochemiluminescence （ECL） via TiO2 nanoparticles （TiO2 NPs） and the outstanding quencher of polydopamine （PDA） decorated Au nanoparticles （Au@PDA NPs） for ultrasensitive detection of carcinoembryonic antigen （CEA） has been successfully achieved. The ECL of CdSe@ZnS QDs with different sizes has been investigated carefully, especially cooperation with TiO2 NPs. Au@PDA NPs have been synthesized and characterized by transmission electron microscopy （TEM） and UV-Vis spectrum, which acted as ECL quenchers to label the secondary antibody （Ab2） of CEA to form Ab2/Au@PDA NPs conjugates. The sandwich-structured immunosensor was formed between capture antibody （Abl） on CdSe@ZnS QDs/TiO2 NPs/glassy carbon electrode, CEA and Ab2/Au@PDA NPs conjugates, resulting in a proportional ECL quenching signal relevant to the CEA concentration. Thus, CEA as a model biomarker has been detected in the linear range from 0.001 to 100 ng mL^-1 with a limit of detection of 0.35 pg mL^-1 （S/N = 3）.展开更多
Signal-induced noise(SIN) in a photomultiplier tube(PMT) introduces bias into the Na density results that are retrieved from the backscattered signals of Na resonance fluorescence lidar systems. The response character...Signal-induced noise(SIN) in a photomultiplier tube(PMT) introduces bias into the Na density results that are retrieved from the backscattered signals of Na resonance fluorescence lidar systems. The response characteristics of a PMT when stimulated by a series of light pulses with a fixed width of 1 μs are therefore used to develop a precise SIN model to estimate the relative error caused by SIN. Unless the strong signals that are returned from the lower atmosphere are excluded, the measured density results are always smaller than the actual values, and the resulting relative error may be 50% or more. Three potential solutions to reduce the SIN were quantified for comparison, including use of a chopper system, use of a gated circuit, and separation of the laser beam and the telescope receiver. When optimized parameters are used for these technologies, the relative error can then be reduced to less than 2%.展开更多
An interferometer based optical sensor for displacement measurement is reported. This method requires quite simple signal processing as well as least electronic components. Referring to this technique, two photodiodes...An interferometer based optical sensor for displacement measurement is reported. This method requires quite simple signal processing as well as least electronic components. Referring to this technique, two photodiodes spatially shifted by 90 degrees were used. The output of photodiodes was converted into rectangular signals which were extracted in LabVIEW using the data acquisition card without using an analog to digital converters （ADC）. We have also processed the signals in C＋＋ after acquiring via parallel port. A Michelson interferometer configuration was used to produce linear fringes for the detection of displacements. The displacement less than 100nm could be measured using this technique.展开更多
Objective： The aim of this study was to test the protective effect of mesenchymal stem cells （MSCs） on cardiomyocytes in vitro and to investigate the anti-apoptotic signaling pathway. Methods： MSCs from Sprague-Da...Objective： The aim of this study was to test the protective effect of mesenchymal stem cells （MSCs） on cardiomyocytes in vitro and to investigate the anti-apoptotic signaling pathway. Methods： MSCs from Sprague-Dawley （SD） rats were separated and cultured. MSC medium was collected from MSCs （DMEM） under hypoxia. Cultured cardiomyocytes from neonatal cultured in serum-free Dulbecco＇s modified eagle medium SD rats were exposed to hypoxia/reoxygenation （H/R） and treated with MSC medium. The apoptotic cardiomyocytes were stained with Annexin-V-fluorescein isothiocyanate （FITC）, Hoechst 33342 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling （TUNEL）. The mitochondrial transmembrane potential of cardiomyocytes was assessed using a fluorescence microscope. The expression of Bcl-2, Bax, cyto- chrome C, apoptosis-induced factor （AIF）, and caspase-3 was tested by Western blot analysis. Results： Our data demonstrated that MSC medium reduced H/R-induced cardiomyocyte apoptosis, increased the Bcl-2/Bax ratio, and reduced the release of cyto- chrome C and AIF from mitochondria into the cytosol. Conclusion： MSCs protected the cardiomyocytes from H/R-induced apoptosis through a mitochondrial pathway in a paracrine manner.展开更多
A new single-mode optoelectronic oscillator(OEO) with three coupled cavities is proposed and demonstrated. A Fabry-Perot(F-P) cavity fiber laser and an optical-electrical feedback branch are coupled together to constr...A new single-mode optoelectronic oscillator(OEO) with three coupled cavities is proposed and demonstrated. A Fabry-Perot(F-P) cavity fiber laser and an optical-electrical feedback branch are coupled together to construct an optoelectronic oscillator, where the F-P cavity fiber laser serves as a light source, and a modulator is placed in the laser cavity to implement reciprocating modulation, which simultaneously splits the laser cavity into two parts and forms a dual-loop configuration. To complete an optoelectronic oscillator, part of optical signal is output from the F-P cavity to implement the feedback modulation, which constructs the third cavity. Since only the oscillation signal satisfies the requirements of all the three cavities, a single-mode oscillation can be finally achieved. Three resonant cavities are successfully designed without adding more optoelectronic devices, and the side-modes can be well suppressed with low cost. The oscillation condition is theoretically analyzed. In the experimental demonstration, a 20 GHz single longitudinal mode microwave signal is successfully obtained.展开更多
Ca3Co409/Nb-SrTiO3 heterojunction with good rectifying behavior at room temperature was fabricated by growing a layer of Ca3Co409 film on the lwt% Nb-doped SrTiO3 substrate by means of the chemical solution deposition...Ca3Co409/Nb-SrTiO3 heterojunction with good rectifying behavior at room temperature was fabricated by growing a layer of Ca3Co409 film on the lwt% Nb-doped SrTiO3 substrate by means of the chemical solution deposition technique. A large open-circuit voltage signal with the response time of tens of nanosecond was observed at room temperature when the Ca3Co409 layer of the heterojunction was illuminated under the 308 nm irradiation and no voltage signal was detected under the 10.6 gun irradiation. A mechanism based on the photovoltaic effect of a p-n junction was proposed to explain the experimental results. The present work shows a great potential of this new heterojunction as photoelectric devices.展开更多
The surface electromyography （SEMG） is a complicated biomedical signal, generated during voluntary or involuntary muscle activities and these muscle activities are always controlled by the nervous system. In this pa...The surface electromyography （SEMG） is a complicated biomedical signal, generated during voluntary or involuntary muscle activities and these muscle activities are always controlled by the nervous system. In this paper, the processing and analysis of SEMG signals at multiple muscle points for different operations were carried out. Myoelectric signals were detected using designed acquisition setup which consists of an instrumenta- tion amplifier, filter circuit, an amplifier with gain adjustment. Fhrther, Labview^-based data programming code was used to record SEMG signals for independent activities. The whole system consists of bipolar noninvasive electrodes, signal acquisition protocols and signal conditioning at different levels. This work uses recorded SEMG signals generated by biceps and triceps muscles for four different arm activities. Feature extraction was done on the recorded signal for investigating the voluntary muscular contraction relationship for exercising statistic measured index method to evaluate distance between two independent groups by directly addressing the quality of signal in separability class for different arm movements. Thereafter repeated factorial analysis of variance technique was implemented to evaluate the effectiveness of processed signal. From these results, it demonstrates that the proposed method can be used as SEMG feature evaluation index.展开更多
文摘A small-signal equivalent circuit model and the ted. The equivalent lumped circuit, which takes the main extraction techniques for photodetector chips are presen- factors that limit a photodetector＇s RF performance into consideration,is first determined based on the device＇s physical structure. The photodetector＇s S parameters are then on-wafer measured, and the measured raw data are processed with further calibration. A genetic algorithm is used to fit the measured data, thereby allowing us to calculate each parameter value of the model. Experimental resuits show that the modeled parameters are well matched to the measurements in a frequency range from 130MHz to 20GHz, and the proposed method is proved feasible. This model can give an exact description of the photodetector chip＇s high frequency performance,which enables an effective circuit-level prediction for photodetector and optoelectronic integrated circuits.
文摘A 0. 5mV high sensitivity,200Mbps CMOS limiting amplifier （LA） with 72dB ultra wide dynamic range is described. A novel active DC offset cancellation loop is elaborately analyzed and designed to achieve this performance. Using a signal path, a received signal strength indicator （RSSI）, based on the piecewise-linear approximation, is realized with a ± 2dB logarithmic accuracy in a 60dB indicating range. The architecture of the LA and RSSI employed is determined by the optimal sensitivity and RSSI accuracy for a specified speed, gain, and power consumption. It consumes 60mW from a single 5V supply. The active area is 1.05mm^2 using standard 5V 0.6μm CMOS technology.
文摘The transmission delay of photogenerated carriers in a CMOS-process-compatible double photodiode (DPD) is analyzed by using device simulation.The DPD small signal equivalent circuit model which includes transmission delay of photogenerated carriers is given.From analysis on the frequency domain of the circuit model the device has two poles.One has the relationship with junction capacitance and the DPD’s load,the other with the depth and the doping concentration of the N-well in the DPD.Different depth of the N-well and different area of the DPDs with bandwidth were compared.The analysis results are important to design the high speed DPDs.
基金Spsonsored by the National Natural Science Foundation of China (Grant No.60274058).
文摘Proposes an H_∞ deconvolution design for time-delay linear continuous-time systems. We first analyze the general structure and innovation structure of the H_∞ deconvolution filter. The deconvolution filter with innovation structure is made up of an output observer and a linear mapping, where the latter reflects the internal connection between the unknown input signal and the output estimate error. Based on the bounded real lemma, a time domain design approach and a sufficient condition for the existence of deconvolution filter are presented. The parameterization of the deconvolution filter can be completed by solving a Riccati equation. The proposed method is useful for the case that does not require statistical information about disturbances. At last, a numerical example is given to demonstrate the performance of the proposed filter.
基金National Natural Science Foundation of China( Grant No.10 2 340 70 )NaturalScience Foundation of Fujian Province of China( Grant No.C0 310 0 2 8)
文摘A new method of phase spectral analysis of EEG is proposed for the comparative analysis of phase spectra between normal EEG and epileptic EEG signals based on the wavelet decomposition technique. By using multiscale wavelet decomposition,the original EEGs are mapped to an orthogonal wavelet space,such that the variations of phase can be observed at multiscale. It is found that the phase (and phase difference) spectra of normal EEGs are distinct from that of epileptic EEGs. That is the variations of phase (and phase difference) of normal EEGs have a distinct periodic pattern with the electrical activity proceeds in the brain,but do not the epileptic EEGs. For epileptic EEGs,only at those transient points,the phase variations are obvious. In order to verify these results with the observational data,the phase variations of EEGs in principal component space are observed and found that,the features of phase spectra is in correspondence with that the wavelet space. These results make it possible to view the behavior of EEG rhythms as a dynamic spectrum.
基金Sponsored by the National High Technology Research and Development Program (863 ) of China (Grant No.2003AA404210, 2005AA404250,2003AA404210, 2006AA01Z443)
文摘The stronglink with muhi-try function based on MEMS technology and the PC startup in authentication system have been designed and fabricated. The generation principle and structure of UQS code are introduced, which consists of two groups of metal counter-meshing gears, two pawl/ratchet mechanisms, two driving micromotors and two resetting micromotors. The energy-coupling element is a photoelectric sensor with a circular and notched plate. It is fabricated using the UV-LiGA process and precision mechanical engineering. The PC startup authentication system is controlled by BIOS program, which is written into the chip according with special format. The program in BIOS output signals controls the running of stronglink to finish the process of authentication. The device can run more than 10000 times before a stop. The driving voltage is 12 V, and the normal decoding time is 3 s.
文摘This paper describes relatively simple stochastic model of the total ground irradiance of horizontal surface. For this purpose clearness index is modeled as a stochastic signal. The parameters of clearness index stochastic signal are chosen to fit values of daily mean insolation for each month for the location of Zagreb, Croatia. Complete model has been done in MATLAB. This model can be used for Monte Carlo simulations of technical solar systems such as photovoltaic systems or solar thermal energy systems.
基金supported by the National Natural Science Foundation of China (No.51005188)the Fund of Key Laboratory of Manufacturing and Automation of Xihua University (No.SZJJ2009-023)the University Talent Foundation of Xihua University (No.R0720221)
文摘In order to improve the test accuracy of CCD,a new type of CCD device is proposed.Several columns(rows) of photoelectric diodes(PDs) are combined together,and staggered with the distance of H1=H/N,where H is the space between two adjacent PDs,and N is the number of columns(rows).The photoelectric signals are collected simultaneously by multi-channel A/D,and the accurate measurement result is obtained through appropriate signal processing.Without changing the size or space of PDs,more photographic pixels are arranged in the given direction within a finite length.Diameters of three standard poles are measured by a single CCD and two staggered CCDs,respectively with length of 30 mm and diameters of 5 mm,8 mm and 12 mm,respectively.The results show that the accuracy of double staggered CCDs is two times of that of single CCD.The new type of CCDs can avoid the impact of PD space theoretically and higher measurement accuracy can be obtained.
基金supported by the National Natural Science Foundation of China (21575022, 21535003)the National High Technology Research and Development Program of China (2015AA020502)+1 种基金the Open Research Fund of Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast Universitythe Fundamental Research Funds for the Central Universities (KYLX15-0127)
文摘In this work, a double signal amplified immunosen- sor based on the enhanced CdSe@ZnS quantum dots （QDs） electrochemiluminescence （ECL） via TiO2 nanoparticles （TiO2 NPs） and the outstanding quencher of polydopamine （PDA） decorated Au nanoparticles （Au@PDA NPs） for ultrasensitive detection of carcinoembryonic antigen （CEA） has been successfully achieved. The ECL of CdSe@ZnS QDs with different sizes has been investigated carefully, especially cooperation with TiO2 NPs. Au@PDA NPs have been synthesized and characterized by transmission electron microscopy （TEM） and UV-Vis spectrum, which acted as ECL quenchers to label the secondary antibody （Ab2） of CEA to form Ab2/Au@PDA NPs conjugates. The sandwich-structured immunosensor was formed between capture antibody （Abl） on CdSe@ZnS QDs/TiO2 NPs/glassy carbon electrode, CEA and Ab2/Au@PDA NPs conjugates, resulting in a proportional ECL quenching signal relevant to the CEA concentration. Thus, CEA as a model biomarker has been detected in the linear range from 0.001 to 100 ng mL^-1 with a limit of detection of 0.35 pg mL^-1 （S/N = 3）.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41404120, 41521063 & 41327801)
文摘Signal-induced noise(SIN) in a photomultiplier tube(PMT) introduces bias into the Na density results that are retrieved from the backscattered signals of Na resonance fluorescence lidar systems. The response characteristics of a PMT when stimulated by a series of light pulses with a fixed width of 1 μs are therefore used to develop a precise SIN model to estimate the relative error caused by SIN. Unless the strong signals that are returned from the lower atmosphere are excluded, the measured density results are always smaller than the actual values, and the resulting relative error may be 50% or more. Three potential solutions to reduce the SIN were quantified for comparison, including use of a chopper system, use of a gated circuit, and separation of the laser beam and the telescope receiver. When optimized parameters are used for these technologies, the relative error can then be reduced to less than 2%.
文摘An interferometer based optical sensor for displacement measurement is reported. This method requires quite simple signal processing as well as least electronic components. Referring to this technique, two photodiodes spatially shifted by 90 degrees were used. The output of photodiodes was converted into rectangular signals which were extracted in LabVIEW using the data acquisition card without using an analog to digital converters （ADC）. We have also processed the signals in C＋＋ after acquiring via parallel port. A Michelson interferometer configuration was used to produce linear fringes for the detection of displacements. The displacement less than 100nm could be measured using this technique.
基金supported by the National Natural Science Foundation of China (No.30670868)the Natural Science Foundation of Zheji-ang Province,China (No.R206007)
文摘Objective： The aim of this study was to test the protective effect of mesenchymal stem cells （MSCs） on cardiomyocytes in vitro and to investigate the anti-apoptotic signaling pathway. Methods： MSCs from Sprague-Dawley （SD） rats were separated and cultured. MSC medium was collected from MSCs （DMEM） under hypoxia. Cultured cardiomyocytes from neonatal cultured in serum-free Dulbecco＇s modified eagle medium SD rats were exposed to hypoxia/reoxygenation （H/R） and treated with MSC medium. The apoptotic cardiomyocytes were stained with Annexin-V-fluorescein isothiocyanate （FITC）, Hoechst 33342 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling （TUNEL）. The mitochondrial transmembrane potential of cardiomyocytes was assessed using a fluorescence microscope. The expression of Bcl-2, Bax, cyto- chrome C, apoptosis-induced factor （AIF）, and caspase-3 was tested by Western blot analysis. Results： Our data demonstrated that MSC medium reduced H/R-induced cardiomyocyte apoptosis, increased the Bcl-2/Bax ratio, and reduced the release of cyto- chrome C and AIF from mitochondria into the cytosol. Conclusion： MSCs protected the cardiomyocytes from H/R-induced apoptosis through a mitochondrial pathway in a paracrine manner.
基金supported by the National Natural Science Foundation of China(Nos.61061004 and 61465002)the Program for New Century Excellent Talents in University of Ministry of Education of China(No.NCET-10-0099)
文摘A new single-mode optoelectronic oscillator(OEO) with three coupled cavities is proposed and demonstrated. A Fabry-Perot(F-P) cavity fiber laser and an optical-electrical feedback branch are coupled together to construct an optoelectronic oscillator, where the F-P cavity fiber laser serves as a light source, and a modulator is placed in the laser cavity to implement reciprocating modulation, which simultaneously splits the laser cavity into two parts and forms a dual-loop configuration. To complete an optoelectronic oscillator, part of optical signal is output from the F-P cavity to implement the feedback modulation, which constructs the third cavity. Since only the oscillation signal satisfies the requirements of all the three cavities, a single-mode oscillation can be finally achieved. Three resonant cavities are successfully designed without adding more optoelectronic devices, and the side-modes can be well suppressed with low cost. The oscillation condition is theoretically analyzed. In the experimental demonstration, a 20 GHz single longitudinal mode microwave signal is successfully obtained.
基金supported by the National Natural Science Foundation of China (Grant No.10904030)the Key Project of Hebei Education Department (Grant No.ZD200909)
文摘Ca3Co409/Nb-SrTiO3 heterojunction with good rectifying behavior at room temperature was fabricated by growing a layer of Ca3Co409 film on the lwt% Nb-doped SrTiO3 substrate by means of the chemical solution deposition technique. A large open-circuit voltage signal with the response time of tens of nanosecond was observed at room temperature when the Ca3Co409 layer of the heterojunction was illuminated under the 308 nm irradiation and no voltage signal was detected under the 10.6 gun irradiation. A mechanism based on the photovoltaic effect of a p-n junction was proposed to explain the experimental results. The present work shows a great potential of this new heterojunction as photoelectric devices.
文摘The surface electromyography （SEMG） is a complicated biomedical signal, generated during voluntary or involuntary muscle activities and these muscle activities are always controlled by the nervous system. In this paper, the processing and analysis of SEMG signals at multiple muscle points for different operations were carried out. Myoelectric signals were detected using designed acquisition setup which consists of an instrumenta- tion amplifier, filter circuit, an amplifier with gain adjustment. Fhrther, Labview^-based data programming code was used to record SEMG signals for independent activities. The whole system consists of bipolar noninvasive electrodes, signal acquisition protocols and signal conditioning at different levels. This work uses recorded SEMG signals generated by biceps and triceps muscles for four different arm activities. Feature extraction was done on the recorded signal for investigating the voluntary muscular contraction relationship for exercising statistic measured index method to evaluate distance between two independent groups by directly addressing the quality of signal in separability class for different arm movements. Thereafter repeated factorial analysis of variance technique was implemented to evaluate the effectiveness of processed signal. From these results, it demonstrates that the proposed method can be used as SEMG feature evaluation index.
