A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filte...A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filter via a detector respectively. The central frequencies of the two filters are selected adaptively according to the disturbance frequency. The disturbance frequency is obtained by either frequency spectrum of the two interferometers outputs. An alarm is given out only when the Sagnac interferometer output is changed. A disturbance position is determined by calculating a time difference with a cross-correlation method between the filter output connected to the Sagnac interferometer and derivative of the filter output connected to the Mach-Zehnder interferometer. The frequency spectrum, derivative and cross-correlation are obtained by a signal processing system. Theory analysis and simulation results are presented. They show that the system structure and location method are effective, accurate, and immune to environmental variations.展开更多
Hypoxia is a disorder in which the tissues are not oxygenated adequately.The lack of oxygen may cause irreversible damage to the major organs such as the brain,heart and lungs.In severe cases,coma,seizures,and death m...Hypoxia is a disorder in which the tissues are not oxygenated adequately.The lack of oxygen may cause irreversible damage to the major organs such as the brain,heart and lungs.In severe cases,coma,seizures,and death may happen.In addition to the routine medication,acupuncture.treatment has been applied as a complementary treatment to counter hypoxia.In this paper,the optical fiber acupuncture needle was fabricated using the optical fiber imbedding into the metal capillary tube with needle tip,therefore made it easy to insert into the body for the laser treatment.The laser optical fiber needle treatment to the ST36 acupoint conducted with the laser.irradiation intra body.The normobaric hypoxia tolerance test results in mice show that the optical fber needle treatment to the ST36 acupoint with laser acupuncture appears to improve the tolerance to hypoxia.The mice treated with laser acupuncture expressed high level of IL-1βin serum.Our results suggest that laser optical fiber needle acupuncture may serve as a potential treatment for hypoxia.展开更多
Supercontinuum (SC) generation has attracted a significant scientific interest in the past decades due to its promising applications covering the fields of metrology, spectroscopy, defense, as well as medical treatmen...Supercontinuum (SC) generation has attracted a significant scientific interest in the past decades due to its promising applications covering the fields of metrology, spectroscopy, defense, as well as medical treatments. To date, researchers are devoted to improving the spectral width and flatness of SC generation by using specialty optical fibers. The flatness of the spectrum is of importance because it can improve the accuracy of measurement in practical applications. This paper summarizes the theory of SC, the state of the art of flat SC generation using optical fiber including photonic crystal fibers, soft glass fibers as well as germania-doped fibers, and suggests the future research direction of flat SC light source.展开更多
Explosive synchronization(ES)is a kind of first-order jump phenomenon that exists in physical and biological systems.In recent years,researchers have focused on ES between single-layer and multi-layer networks.Most re...Explosive synchronization(ES)is a kind of first-order jump phenomenon that exists in physical and biological systems.In recent years,researchers have focused on ES between single-layer and multi-layer networks.Most research on complex networks with delay has focused on single-layer or double-layer networks,multi-layer networks are seldom explored.In this paper,we propose a Kuramoto model of frequency weights in multi-layer complex networks with delay and star connections between layers.Through theoretical analysis and numerical verification,the factors affecting the backward critical coupling strength are analyzed.The results show that the interaction between layers and the average node degree has a direct effect on the backward critical coupling strength of each layer network.The location of the delay,the size of the delay,the number of network layers,the number of nodes,and the network topology are revealed to have no direct impact on the backward critical coupling strength of the network.Delay is introduced to explore the influence of delay and other related parameters on ES.展开更多
The characteristics of the best known defect centers E' in silica optical fiber material irradiated with ray were investigated by ESR at room temperature.A mechanism model of production of the E' center defect...The characteristics of the best known defect centers E' in silica optical fiber material irradiated with ray were investigated by ESR at room temperature.A mechanism model of production of the E' center defect was established.The production of E' center includes two processes creation and activation.The strained bonds(or oxygen replacement) in silica networks lead to the creation of new defects whose concentration increases linearly with the dose.The pre-existing defects produce the activation,which tends to saturation.According to this model,the relation of E' center concentration changing with irradiation dose was obtained theoretically.The results are in good agreement with the experimental results.展开更多
In this paper, a novel surface-enhanced Raman scattering (SERS) sensor combined with fused biconical taper fiber (FBTF) and film coated with silver sols is proposed. This structure is designed to significantly inc...In this paper, a novel surface-enhanced Raman scattering (SERS) sensor combined with fused biconical taper fiber (FBTF) and film coated with silver sols is proposed. This structure is designed to significantly increase the SERS active surface when the length of the taper is increased and the radius is reduced, since the penetration depth is inversely proportional to the taper radius and proportional to the taper length according to the fiber-optic evanescent-wave theory. Based on the SERS sensing principle, the feasibility of FBTF sensor is analyzed in this paper. As a result, the Raman spectrum of R6G is obtained from the fused biconical taper zone surface coating with the silver sols in our experiments. The detected concentration is up to 10-7mol/L.展开更多
We demonstrate a passively harmonic mode-locked(PHML) fiber laser operating at the L-band using carbon nanotubes polyvinyl alcohol(CNTs-PVA) film. Under suitable pump power and an appropriate setting of the polari...We demonstrate a passively harmonic mode-locked(PHML) fiber laser operating at the L-band using carbon nanotubes polyvinyl alcohol(CNTs-PVA) film. Under suitable pump power and an appropriate setting of the polarization controller(PC), the 54^(th) harmonic pulses at the L-band are generated with the side mode suppression ratio(SMSR) better than 44 dB and a repetition frequency of 503.37 MHz. Further increasing the pump power leads to a higher frequency of 550 MHz with compromised stability of 38.5 dB SMSR. To the best of our knowledge, this is the first demonstration on the generation of L-band PHML pulses from an Er-doped fiber laser based on CNTs.展开更多
We demonstrate a simultaneous transmission of time-frequency and data over a 160-km urban business network in Shanghai.The signals are transmitted through a cascaded optical link consisting of 48 km and 32 km,which ar...We demonstrate a simultaneous transmission of time-frequency and data over a 160-km urban business network in Shanghai.The signals are transmitted through a cascaded optical link consisting of 48 km and 32 km,which are connected by an optical relay.The metrological signals are inserted into the communication network using dense wavelength division multiplexing.The influence of the interference between different signals has been discussed.The experimental results demonstrate that the radio frequency(RF)instability can reach 2.1×10^(-14)at 1 s and 2.3×10^(-17)at 10,000 s,and the time interval transfer of one pulse per second(1 PPS)signal with less than 10 ps at 1 s is obtained.This work paves the way for the widespread dissemination of ultra-stable time and frequency signals over the communication networks.展开更多
We demonstrate experimentally fabrication of CO2 laser written long-period fiber gratings (LPFGs) in single-mode fiber (SMF) under tension. New transmission dips can be generated due to the frozen-in stress in the...We demonstrate experimentally fabrication of CO2 laser written long-period fiber gratings (LPFGs) in single-mode fiber (SMF) under tension. New transmission dips can be generated due to the frozen-in stress in the fiber under tension. Dynamics analysis of laser writing process is performed to study the mechanism of the grating inscription. Experimental results show that the wavelength shift of new generated resonance dips can shift towards the longer or shorter wavelength with the increase of laser scanning cycles for gratings with different pitches.展开更多
A temperature sensor is demonstrated and fabricated by coating the single-mode tapered optical fiber with temperature-sensitive silicone rubber. It works on the change of the evanescent fields in the tapered optical f...A temperature sensor is demonstrated and fabricated by coating the single-mode tapered optical fiber with temperature-sensitive silicone rubber. It works on the change of the evanescent fields in the tapered optical fiber. Small changes in the refractive index of coating film greatly influence the power of evanescent fields, which modulate the transmission optical power in the waist region. The range of temperature measured is from -20℃ to 70 ℃. The results show that the temperature sensor has high temperature sensitivity (0.012 mW/℃) and good repeatability.展开更多
In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneous...In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave induced by the Brillouin amplification injects and locks the Fabry-Perot (FP) laser to output a signal-mode optical source, which works as the uplink optical carrier.展开更多
Cognitive radio (CR) is a promising technology deemed to improve the efficiency of spectrum utilization. This paper considers a spectrum underlay cognitive radio network, in which the cognitive users (CUs) are all...Cognitive radio (CR) is a promising technology deemed to improve the efficiency of spectrum utilization. This paper considers a spectrum underlay cognitive radio network, in which the cognitive users (CUs) are allowed to use the radio spectrum concurrently with the primary users (PUs) under the interference temperature constraint. We investigate the system performance by using the proposed joint channel and power allocation scheme under two transmit strategies to achieve higher data rates and performance diversity gain respectively. Simulation results show that the proposed scheme provides a significant improvement on the bit error rate (BER) performance and spectrum efficiency of a cognitive wireless network.展开更多
This paper proposes a new phase feature derived from the formant instantaneous characteristics for speech recognition (SR) and speaker identification (SI) systems. Using Hilbert transform (HT), the formant chara...This paper proposes a new phase feature derived from the formant instantaneous characteristics for speech recognition (SR) and speaker identification (SI) systems. Using Hilbert transform (HT), the formant characteristics can be represented by instantaneous frequency (IF) and instantaneous bandwidth, namely formant instantaneous characteristics (FIC). In order to explore the importance of FIC both in SR and SI, this paper proposes different features from FIC used for SR and SI systems. When combing these new features with conventional parameters, higher identification rate can be achieved than that of using Mel-frequency cepstral coefficients (MFCC) parameters only. The experiment results show that the new features are effective characteristic parameters and can be treated as the compensation of conventional parameters for SR and SI.展开更多
Transmission properties of fractal Cantor distribution with left-handed materials (LHM) are investigated. The transmittance and reflectance spectra can be calculated by using the optical transmission matrix method. ...Transmission properties of fractal Cantor distribution with left-handed materials (LHM) are investigated. The transmittance and reflectance spectra can be calculated by using the optical transmission matrix method. Comparing with the conventional Cantor multilayers, these structures with LHM have double functions of stopbands and defects. Through adjusting the thickness of dielectric layers, the properties of stopbands and defects can be obtained, respectively. For stopbands, a broad stopband filter is studied. For defect modes, multi-frequencies narrow passband filters are proposed.展开更多
A novel architecture of wavelength-division multiplexing/optical code division multiplexing access-passive optical network (WDM/OCDMA-PON) based on superstructure fiber Bragg grating (SSFBG) and wavelength re-modu...A novel architecture of wavelength-division multiplexing/optical code division multiplexing access-passive optical network (WDM/OCDMA-PON) based on superstructure fiber Bragg grating (SSFBG) and wavelength re-modulation technology is proposed. In this scheme, WDM is overlaid on OCDMA channel in a single network by virtue of a kind of SSFBC, and the total capacity of hybrid PON can be extended by regulating the transmission power reasonably. Re, modulation technology is also a good method to save wavelength-specific components at the optical network unit (ONU) and cost of wavelength management on the customer side. In simulation system, 1.25 Gb/s up/downstream data are transported with good performance. In addition the crosstalk penalties from adjacent wavelength channels (with the same OC) are found to be negligible in upstream and downstream transmissions.展开更多
In order to verify the properties of the light propagating through a gradient-index (GRIN) fibre probe for optical coherence tomography (OCT), numerical simulation using the optical software GLAD is carried out. F...In order to verify the properties of the light propagating through a gradient-index (GRIN) fibre probe for optical coherence tomography (OCT), numerical simulation using the optical software GLAD is carried out. Firstly, the model of the GRIN fibre probe is presented, which is consisted of a single mode fibre (SMF), a no-core fibre (NCF), a GRIN fibre lens and an air path. Then, the software GLAD is adopted to numerically investigate how the lengths of the NCF and the GRIN fibre lens influence the performance of the Gaussian beam focusing through the GRIN fibre probe. The simulation results are well consistent with the experimental ones, showing that the GLAD based numerical simulation technique is an intuitive and effective tool for the verification of the properties of the light propagation. In this paper, we find that on the conditions of a constant GRIN fibre lens length of 0.1 mm and an NCF length of 0.36 mm, the working distance of the probe will be 0.75 mm and the focus spot size is 32 μm.展开更多
Optimal resource allocation is critical to the efficiency of cooperative communiCations. In this paper, we develop an auction-based power allocation mechanism for network-coded cooperation in wireless networks, in whi...Optimal resource allocation is critical to the efficiency of cooperative communiCations. In this paper, we develop an auction-based power allocation mechanism for network-coded cooperation in wireless networks, in which the sources compete for the relay power for maximum utility, while the relay node assigns the resource in accordance with the bids from the sources. Moreover, to improve the resource utilization, the relay node is allowed to perform network coding across the received information for the same destination. Finally, numerical results validate the performance of the proposed algorithm, and show that there exists a tradeoff between the system outage probability and the power consumed at the relay node.展开更多
Localization of the sensor nodes is a key supporting technology in wireless sensor networks (WSNs). In this paper, a real-time localization estimator of mobile node in WSNs based on extended Kalman filter (KF) is ...Localization of the sensor nodes is a key supporting technology in wireless sensor networks (WSNs). In this paper, a real-time localization estimator of mobile node in WSNs based on extended Kalman filter (KF) is proposed. Mobile node movement model is analyzed and online sequential iterative method is used to compute location result. The detailed steps of mobile sensor node self-localization adopting extended Kalman filter (EKF) is designed. The simulation results show that the accuracy of the localization estimator scheme designed is better than those of maximum likelihood estimation (MLE) and traditional KF algorithm.展开更多
基金Project supported by the Innovation Program of Education Commission of Shanghai Municipality (Grant No.10YZ19)the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Shanghai Key Laboratory of Specialty Fiber Optics and Optical Access Networks (Grant No.SKLSFO200903)
文摘A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filter via a detector respectively. The central frequencies of the two filters are selected adaptively according to the disturbance frequency. The disturbance frequency is obtained by either frequency spectrum of the two interferometers outputs. An alarm is given out only when the Sagnac interferometer output is changed. A disturbance position is determined by calculating a time difference with a cross-correlation method between the filter output connected to the Sagnac interferometer and derivative of the filter output connected to the Mach-Zehnder interferometer. The frequency spectrum, derivative and cross-correlation are obtained by a signal processing system. Theory analysis and simulation results are presented. They show that the system structure and location method are effective, accurate, and immune to environmental variations.
基金the Natural Science Foundation of China(NSFC)(61107076,61177088,61475095,61027015 and 31571430)Shanghai Pujiang Program(14PJ1407700)+2 种基金Health and Fam-ily Planning Commission Foundation of Shanghai(201440300)National Program(on Key Basic Research Project(973 Program,2012CB723405,2014CB541804)the Key Laboratory of Specialty Fiber Optics and Optical Access Networks(SKLSF02013-02 and SKLSFO2015-01).
文摘Hypoxia is a disorder in which the tissues are not oxygenated adequately.The lack of oxygen may cause irreversible damage to the major organs such as the brain,heart and lungs.In severe cases,coma,seizures,and death may happen.In addition to the routine medication,acupuncture.treatment has been applied as a complementary treatment to counter hypoxia.In this paper,the optical fiber acupuncture needle was fabricated using the optical fiber imbedding into the metal capillary tube with needle tip,therefore made it easy to insert into the body for the laser treatment.The laser optical fiber needle treatment to the ST36 acupoint conducted with the laser.irradiation intra body.The normobaric hypoxia tolerance test results in mice show that the optical fber needle treatment to the ST36 acupoint with laser acupuncture appears to improve the tolerance to hypoxia.The mice treated with laser acupuncture expressed high level of IL-1βin serum.Our results suggest that laser optical fiber needle acupuncture may serve as a potential treatment for hypoxia.
基金National Natural Science Foundation of China (Grant No. 61605108, 61735009, 61422507)Young Oriental Scholarship of Shanghai.
文摘Supercontinuum (SC) generation has attracted a significant scientific interest in the past decades due to its promising applications covering the fields of metrology, spectroscopy, defense, as well as medical treatments. To date, researchers are devoted to improving the spectral width and flatness of SC generation by using specialty optical fibers. The flatness of the spectrum is of importance because it can improve the accuracy of measurement in practical applications. This paper summarizes the theory of SC, the state of the art of flat SC generation using optical fiber including photonic crystal fibers, soft glass fibers as well as germania-doped fibers, and suggests the future research direction of flat SC light source.
文摘Explosive synchronization(ES)is a kind of first-order jump phenomenon that exists in physical and biological systems.In recent years,researchers have focused on ES between single-layer and multi-layer networks.Most research on complex networks with delay has focused on single-layer or double-layer networks,multi-layer networks are seldom explored.In this paper,we propose a Kuramoto model of frequency weights in multi-layer complex networks with delay and star connections between layers.Through theoretical analysis and numerical verification,the factors affecting the backward critical coupling strength are analyzed.The results show that the interaction between layers and the average node degree has a direct effect on the backward critical coupling strength of each layer network.The location of the delay,the size of the delay,the number of network layers,the number of nodes,and the network topology are revealed to have no direct impact on the backward critical coupling strength of the network.Delay is introduced to explore the influence of delay and other related parameters on ES.
基金Supported by National Program on Key Basic Research Project(973 Program,No.2012CB723405)Natural Science Foundation of China(No.60937003,61077068,61275090,61275051,and 61027015)Shanghai Natural Science Foundation(No.12ZR1411200)
文摘The characteristics of the best known defect centers E' in silica optical fiber material irradiated with ray were investigated by ESR at room temperature.A mechanism model of production of the E' center defect was established.The production of E' center includes two processes creation and activation.The strained bonds(or oxygen replacement) in silica networks lead to the creation of new defects whose concentration increases linearly with the dose.The pre-existing defects produce the activation,which tends to saturation.According to this model,the relation of E' center concentration changing with irradiation dose was obtained theoretically.The results are in good agreement with the experimental results.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61027015, 60677031, 60937003)the Shanghai Leading Academic Discipline Project (Grant No.30108)the Science and Technology Commission of Shanghai Municipality (Grant No.10DZ2210900)
文摘In this paper, a novel surface-enhanced Raman scattering (SERS) sensor combined with fused biconical taper fiber (FBTF) and film coated with silver sols is proposed. This structure is designed to significantly increase the SERS active surface when the length of the taper is increased and the radius is reduced, since the penetration depth is inversely proportional to the taper radius and proportional to the taper length according to the fiber-optic evanescent-wave theory. Based on the SERS sensing principle, the feasibility of FBTF sensor is analyzed in this paper. As a result, the Raman spectrum of R6G is obtained from the fused biconical taper zone surface coating with the silver sols in our experiments. The detected concentration is up to 10-7mol/L.
基金Project supported by the National Natural Science Foundation of China(Grant No.61605107)Young Eastern Scholar Program at Shanghai Institutions of Higher Learning,China(Grant No.QD2015027)+2 种基金the“Young 1000 Talent Plan”Program of Chinathe Open Program of the State Key Laboratory of Advanced Optical Communication Systems and Networks at Shanghai Jiaotong University,China(Grant No.2017GZKF17)RAEng/The Leverhulme Trust Senior Research Fellowships(Grant No.LTSRF1617/13/57).
文摘We demonstrate a passively harmonic mode-locked(PHML) fiber laser operating at the L-band using carbon nanotubes polyvinyl alcohol(CNTs-PVA) film. Under suitable pump power and an appropriate setting of the polarization controller(PC), the 54^(th) harmonic pulses at the L-band are generated with the side mode suppression ratio(SMSR) better than 44 dB and a repetition frequency of 503.37 MHz. Further increasing the pump power leads to a higher frequency of 550 MHz with compromised stability of 38.5 dB SMSR. To the best of our knowledge, this is the first demonstration on the generation of L-band PHML pulses from an Er-doped fiber laser based on CNTs.
基金supported by the National Key Research and Development Program of China(No.2020YFB0408300)the National Natural Science Foundation of China(No.62175246)+1 种基金the Natural Science Foundation of Shanghai(No.22ZR1471100)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.YIPA2021244)。
文摘We demonstrate a simultaneous transmission of time-frequency and data over a 160-km urban business network in Shanghai.The signals are transmitted through a cascaded optical link consisting of 48 km and 32 km,which are connected by an optical relay.The metrological signals are inserted into the communication network using dense wavelength division multiplexing.The influence of the interference between different signals has been discussed.The experimental results demonstrate that the radio frequency(RF)instability can reach 2.1×10^(-14)at 1 s and 2.3×10^(-17)at 10,000 s,and the time interval transfer of one pulse per second(1 PPS)signal with less than 10 ps at 1 s is obtained.This work paves the way for the widespread dissemination of ultra-stable time and frequency signals over the communication networks.
基金Project supported by the Shanghai Pujiang Program (Grant No.09PJ1404600)the New Century Excellent Talents in University, Ministry of Education of China (Grant No.NCET-10-0082)+1 种基金the Shanghai Shuguang Program (Grant No.08SG40)the Shanghai Leading Academic Discipline Project (Grant No.S30108)
文摘We demonstrate experimentally fabrication of CO2 laser written long-period fiber gratings (LPFGs) in single-mode fiber (SMF) under tension. New transmission dips can be generated due to the frozen-in stress in the fiber under tension. Dynamics analysis of laser writing process is performed to study the mechanism of the grating inscription. Experimental results show that the wavelength shift of new generated resonance dips can shift towards the longer or shorter wavelength with the increase of laser scanning cycles for gratings with different pitches.
基金Supported by the National Natural Science Foundation of China ( No. 60972056 ), the Innovation Foundation of Shanghai Education Committee ( No. 09ZZ89) and Shanghai Leading Academic Discipline Project and STCSM ( No.S30108, 08DZ2231100 ).
基金Project supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Universities Foster Innovation Foundation Projects for Major Projects in Ministry of Education (Grant No.708041)
文摘A temperature sensor is demonstrated and fabricated by coating the single-mode tapered optical fiber with temperature-sensitive silicone rubber. It works on the change of the evanescent fields in the tapered optical fiber. Small changes in the refractive index of coating film greatly influence the power of evanescent fields, which modulate the transmission optical power in the waist region. The range of temperature measured is from -20℃ to 70 ℃. The results show that the temperature sensor has high temperature sensitivity (0.012 mW/℃) and good repeatability.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.60377024, 60877053)the Science Foundation of Science and Technology Commission of Shanghai Municipality (Grant No.08DZ1500115)
文摘In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave induced by the Brillouin amplification injects and locks the Fabry-Perot (FP) laser to output a signal-mode optical source, which works as the uplink optical carrier.
基金Project supported by the Shanghai Pujiang Program (Grant No.08PJ14057)the Science and Technology Commission of Shanghai Municipality (Grant No.08220510900)+1 种基金the Innovation Foundation of Shanghai University (Grant No.SHUCX102153)the Cognitive Communications Consortium of the Worldwide Universities' Network
文摘Cognitive radio (CR) is a promising technology deemed to improve the efficiency of spectrum utilization. This paper considers a spectrum underlay cognitive radio network, in which the cognitive users (CUs) are allowed to use the radio spectrum concurrently with the primary users (PUs) under the interference temperature constraint. We investigate the system performance by using the proposed joint channel and power allocation scheme under two transmit strategies to achieve higher data rates and performance diversity gain respectively. Simulation results show that the proposed scheme provides a significant improvement on the bit error rate (BER) performance and spectrum efficiency of a cognitive wireless network.
基金Project supported by the National Natural Science Foundation of China (Grant No.60903186)the Shanghai Leading Academic Discipline Project (Grant No.J50104)
文摘This paper proposes a new phase feature derived from the formant instantaneous characteristics for speech recognition (SR) and speaker identification (SI) systems. Using Hilbert transform (HT), the formant characteristics can be represented by instantaneous frequency (IF) and instantaneous bandwidth, namely formant instantaneous characteristics (FIC). In order to explore the importance of FIC both in SR and SI, this paper proposes different features from FIC used for SR and SI systems. When combing these new features with conventional parameters, higher identification rate can be achieved than that of using Mel-frequency cepstral coefficients (MFCC) parameters only. The experiment results show that the new features are effective characteristic parameters and can be treated as the compensation of conventional parameters for SR and SI.
基金Project supported by the National Natural Science Foundation of China (Grant No.61077068)the Natural Science Foundation of Shanghai Municipality (Grant No.10ZR1411900)+1 种基金the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2231100)
文摘Transmission properties of fractal Cantor distribution with left-handed materials (LHM) are investigated. The transmittance and reflectance spectra can be calculated by using the optical transmission matrix method. Comparing with the conventional Cantor multilayers, these structures with LHM have double functions of stopbands and defects. Through adjusting the thickness of dielectric layers, the properties of stopbands and defects can be obtained, respectively. For stopbands, a broad stopband filter is studied. For defect modes, multi-frequencies narrow passband filters are proposed.
基金Project supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)the Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2231100)
文摘A novel architecture of wavelength-division multiplexing/optical code division multiplexing access-passive optical network (WDM/OCDMA-PON) based on superstructure fiber Bragg grating (SSFBG) and wavelength re-modulation technology is proposed. In this scheme, WDM is overlaid on OCDMA channel in a single network by virtue of a kind of SSFBC, and the total capacity of hybrid PON can be extended by regulating the transmission power reasonably. Re, modulation technology is also a good method to save wavelength-specific components at the optical network unit (ONU) and cost of wavelength management on the customer side. In simulation system, 1.25 Gb/s up/downstream data are transported with good performance. In addition the crosstalk penalties from adjacent wavelength channels (with the same OC) are found to be negligible in upstream and downstream transmissions.
基金supported by the International Cooperation Project of Shanghai Science and Technology Committee,China(Grant No.09530708700)
文摘In order to verify the properties of the light propagating through a gradient-index (GRIN) fibre probe for optical coherence tomography (OCT), numerical simulation using the optical software GLAD is carried out. Firstly, the model of the GRIN fibre probe is presented, which is consisted of a single mode fibre (SMF), a no-core fibre (NCF), a GRIN fibre lens and an air path. Then, the software GLAD is adopted to numerically investigate how the lengths of the NCF and the GRIN fibre lens influence the performance of the Gaussian beam focusing through the GRIN fibre probe. The simulation results are well consistent with the experimental ones, showing that the GLAD based numerical simulation technique is an intuitive and effective tool for the verification of the properties of the light propagation. In this paper, we find that on the conditions of a constant GRIN fibre lens length of 0.1 mm and an NCF length of 0.36 mm, the working distance of the probe will be 0.75 mm and the focus spot size is 32 μm.
基金Project supported by the National Natural Science Foundation of China (Grant No.60802019)the Science and Technology Commission of Shanghai Municipality (Grant No.08220510900)
文摘Optimal resource allocation is critical to the efficiency of cooperative communiCations. In this paper, we develop an auction-based power allocation mechanism for network-coded cooperation in wireless networks, in which the sources compete for the relay power for maximum utility, while the relay node assigns the resource in accordance with the bids from the sources. Moreover, to improve the resource utilization, the relay node is allowed to perform network coding across the received information for the same destination. Finally, numerical results validate the performance of the proposed algorithm, and show that there exists a tradeoff between the system outage probability and the power consumed at the relay node.
基金Project supported by the Shanghai Leading Academic Discipcine Project (Grant No.S30108)the National Natural Science Foundation of China (Grant No.60872021)the Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2231100)
文摘Localization of the sensor nodes is a key supporting technology in wireless sensor networks (WSNs). In this paper, a real-time localization estimator of mobile node in WSNs based on extended Kalman filter (KF) is proposed. Mobile node movement model is analyzed and online sequential iterative method is used to compute location result. The detailed steps of mobile sensor node self-localization adopting extended Kalman filter (EKF) is designed. The simulation results show that the accuracy of the localization estimator scheme designed is better than those of maximum likelihood estimation (MLE) and traditional KF algorithm.