A gated viewing laser radar has an excellent performance in underwater low light level imaging, and it also provides a viable solution to inhibit backscattering. In this paper, a gated viewing imaging system according...A gated viewing laser radar has an excellent performance in underwater low light level imaging, and it also provides a viable solution to inhibit backscattering. In this paper, a gated viewing imaging system according to the demand for real-time imaging is presented, and then the simulation is used to analyze the performance of the real-time gated viewing system. The range accuracy performance is limited by the slice number, the width of gate, the delay time step, the initial delay time, as well as the system noise and atmospheric turbulence. The simulation results indicate that the highest range accuracy can be achieved when the system works with the optimal parameters. Finally, how to choose the optimal parameters has been researched.展开更多
In this paper, the response time of all-optical AND logic gate using the triangular photonic crystal lattice is investigated. The proposed logic gate consists of a photonic crystal nano-resonator formed by changing th...In this paper, the response time of all-optical AND logic gate using the triangular photonic crystal lattice is investigated. The proposed logic gate consists of a photonic crystal nano-resonator formed by changing the size of the dielectric rods. The structure benefits the interference effect mechanism. The contrast ratio of the photonic crystal AND logic gate is obtained as 6 d B. In addition to simplicity, the designed nano-resonator increases the bit rate of logic gate. The delay time and footprint of logic gate are respectively 0.32 ps and 146 μm2. The proposed photonic crystal AND logic gate can operate at a bit rate of 3.12 Tbit/s。展开更多
A multi-deposition multi-annealing technique （MDMA） is introduced into the process of high-k/metal gate MOSFET for the gate last process to effectively reduce the gate leakage and improve the device＇s performance. ...A multi-deposition multi-annealing technique （MDMA） is introduced into the process of high-k/metal gate MOSFET for the gate last process to effectively reduce the gate leakage and improve the device＇s performance. In this paper, we systematically investigate the electrical parameters and the time-dependent dielectric breakdown （TDDB） characteristics of positive channel metal oxide semiconductor （PMOS） under different MDMA process conditions, including the depo- sition/annealing （D＆A） cycles, the D＆A time, and the total annealing time. The results show that the increases of the number of D＆A cycles （from 1 to 2） and D＆A time （from 15 s to 30 s） can contribute to the results that the gate leakage current decreases by about one order of magnitude and that the time to fail （TTF） at 63.2% increases by about several times. However, too many D＆A cycles （such as 4 cycles） make the equivalent oxide thickness （EOT） increase by about 1A and the TTF of PMOS worsen. Moreover, different D＆A times and numbers of D＆A cycles induce different breakdown mechanisms.展开更多
Purpose: Respiratory-gated radiation therapy (RT) using the real-time tumor-tracking radiotherapy (RTRT) system is an effective technique for managing tumor motion. High dosimetric and geometric accuracy is needed;how...Purpose: Respiratory-gated radiation therapy (RT) using the real-time tumor-tracking radiotherapy (RTRT) system is an effective technique for managing tumor motion. High dosimetric and geometric accuracy is needed;however, quality assurance (QA) for respiratory-gated RT using the RTRT system has not been reported. The purpose of this study was to perform QA for respiratorygated RT using the RTRT system. Materials and Methods: The RTRT system detected the position of the fiducial marker and radiation delivery gated to the motion of the marker was performed. The dynamic anthropomorphic thorax phantom was positioned at the isocenter using the fiducial marker in the phantom. The phantom was irradiated only when the fiducial marker was within a three-dimensional gating window of ±2 mm from the planned position. First, the absolute doses were measured using anionization chamber inserted in the phantom under the stationary, gating and non-gating state for sinusoidal (nadir-to-peak amplitude [A]: 20 - 40 mm, breathing period [T]: 2 - 4 s) and the basic respiratory patterns. Second, the dose profiles were measured using Gafchromic films in the phantom under the same conditions. Differences between dose profiles were calculated to evaluate the dosimetric and geometric accuracy. Finally, differences between the actual and measured position of the fiducial marker were calculated to evaluate the tracking accuracy for sinusoidal and basic respiratory patterns. Results: For the sinusoidal patterns, the relative doses were 0.93 for non-gating and 0.99 for gating (A = 20 mm, T = 2 s), 0.94 for non-gating and 1.00 for gating (A = 20 mm, T = 4 s), 0.55 for non-gating and 1.00 for gating (A = 40 mm, T = 4 s), respectively. For the basic respiratory pattern, the relative doses were 1.00 for non-gating and 1.00 for gating, respectively. Compared to the stationary conditions, the differences in lateral distance between the 90% dose of dose profiles were 6.23 mm for non-gating and 0.36 mm for gating (A = 20 mm, T = 2 s), 8.79 mm for non-gating and 1.73 mm for gating (A = 20 mm, T = 4 s), 18.37 mm for non-gating and 0.67 mm for gating (A = 40 mm, T = 4 s), respectively. For the basic respiratory pattern, those were 5.23 mm for non-gating and 0.35 mm for gating. The root mean square (RMS) values of the tracking error were 0.18 mm (A = 20 mm, T = 2 s), 0.14 mm (A = 20 mm, T = 4 s), and 0.21 mm (A = 40 mm, T = 4 s) for sinusoidal and 0.79 mm for the basic respiratory pattern, respectively. Conclusion: We conducted QA for respiratory-gated RT using the RTRT system. The respiratory-gated RT using the RTRT system reduced the blurring effects on dose distribution with high dosimetric and geometric accuracy.展开更多
Long departure-taxi-out time leads to significant airport surface congestion, fuel-burn costs, and excessive emissions of greenhouse gases. To reduce these undesirable effects, a Predicted taxi-out time-based Dynamic ...Long departure-taxi-out time leads to significant airport surface congestion, fuel-burn costs, and excessive emissions of greenhouse gases. To reduce these undesirable effects, a Predicted taxi-out time-based Dynamic Pushback Control(PDPC) method is proposed. The implementation of this method requires two steps: first, the taxi-out times for aircraft are predicted by the leastsquares support-vector regression approach of which the parameters are optimized by an introduced improved Firefly algorithm. Then, a dynamic pushback control model equipped with a linear gate-hold penalty function is built, along with a proposed iterative taxiway queue-threshold optimization algorithm for solving the model. A case study with data obtained from Beijing International airport(PEK) is presented. The taxi-out time prediction model achieves predictive accuracy within 3 min and 5 min by 84.71% and 95.66%, respectively. The results of the proposed pushback method show that total operation cost and fuel-burn cost achieve a 14.0% and 21.1%reduction, respectively, as compared to the traditional K-control policy.(3) From the perspective of implementation, using PDPC policy can significantly reduce the queue length in taxiway and taxi-out time. The total operation cost and fuel-burn cost can be curtailed by 37.2% and 52.1%,respectively, as compared to the non-enforcement of any pushback control mechanism. These results show that the proposed pushback control model can reduce fuel-burn costs and airport surface congestion effectively.展开更多
We characterized the dependence of the timing jitter of an InGaAs/InP single-photon avalanche diode on the excess bias voltage（V（ex）） when operated in 1-GHz sinusoidally gated mode.The single-photon avalanche diod...We characterized the dependence of the timing jitter of an InGaAs/InP single-photon avalanche diode on the excess bias voltage（V（ex）） when operated in 1-GHz sinusoidally gated mode.The single-photon avalanche diode was cooled to-30 degrees Celsius.When the V（ex） is too low（0.2 V-0.8 V） or too high（3 V-4.2 V）,the timing jitter is increased with the V（ex）,particularly at high V（ex）.While at middle V（ex）（1 V-2.8 V）,the timing jitter is reduced.Measurements of the timing jitter of the same avalanche diode with pulsed gating show that this effect is likely related to the increase of both the amplitude of the V（ex） and the width of the gate-on time.For the 1-GHz sinusoidally gated detector,the best jitter of 93 ps is achieved with a photon detection efficiency of 21.4%and a dark count rate of -2.08×10 -5 per gate at the V（ex） of 2.8 V.To evaluate the whole performance of the detector,we calculated the noise equivalent power（NEP） and the afterpulse probability（P（ap））.It is found that both NEP and P（ap） increase quickly when the V（ex） is above 2.8 V.At -2.8-V V（ex）,the NEP and P（ap） are -2.06×10-（16）W/Hz-（1/2） and 7.11%,respectively.Therefore,the detector should be operated with V（ex） of 2.8 V to exploit the fast time response,low NEP and low P（ap）.展开更多
A novel reconfigurable hardware system which uses both muhi-DSP and FPGA to attain high performance and real-time image processing are presented. The system structure and working principle of mainly processing multi-B...A novel reconfigurable hardware system which uses both muhi-DSP and FPGA to attain high performance and real-time image processing are presented. The system structure and working principle of mainly processing multi-BSP board, extended multi-DSP board are analysed. The outstanding advantage is that the communication among different board components of this system is supported by high speed link ports ＆ serial ports for increasing the system performance and computational power. Then the implementation of embedded real-time operating systems （RTOS） by us is discussed in detail. In this system, we adopt two kinds of parallel structures controlled by RTOS for parallel processing of algorithms. The experimental results show that exploitive period of the system is short, and maintenance convenient. Thus it is suitable for real-time image processing and can get satisfactory effect of image recognition.展开更多
Fast and high fidelity quantum control is the key technology of quantum computing. The hybrid system composed of the nitrogen-vacancy center and nearby Carbon-13 nuclear spin is expected to solve this problem. The nit...Fast and high fidelity quantum control is the key technology of quantum computing. The hybrid system composed of the nitrogen-vacancy center and nearby Carbon-13 nuclear spin is expected to solve this problem. The nitrogen-vacancy center electron spin enables fast operations for its strong coupling to the control field, whereas the nuclear spins preserve the coherence for their weak coupling to the environment. In this paper, we describe a strategy to achieve time-optimal control of the Carbon-13 nuclear spin qubit by alternating controlling the nitrogen-vacancy center electron spin as an actuator. We transform the qubit gate operation into a switched system. By using the maximum principle, we study the minimum time control of the switched system and obtain the time-optimal control of the qubit gate operation. We show that the X gate and Y gate operations are within 10μs while the fidelity reaches 0.995.展开更多
Making events recognition more reliable under complex environment is one of the most important challenges for the intelligent recognition system to the ticket gate in the urban rapid rail transit. The motion objects p...Making events recognition more reliable under complex environment is one of the most important challenges for the intelligent recognition system to the ticket gate in the urban rapid rail transit. The motion objects passing through the ticket gate could be described as a series of moving sequences got by sensors that located in the walkway side of the ticket gate. This paper presents a robust method to detect some classes of events of ticket gate in the urban rapid rail transit. Diffused reflectance infrared sensors are used to collect signals. In this paper, the motion objects are here referred to passenger(s) or (and) luggage(s), for which are of frequent occurrences in the ticket gate of the urban railway traffic. Specifically, this paper makes two main contributions: 1) The proposed recognition method could be used to identify several events, including the event of one person passing through the ticket gate, the event of two consecutive passengers passing through the ticket gate without a big gap between them, and the event of a passenger walking through the ticket gate pulling a suitcase;2) The moving time sequence matrix is transformed into a one-dimensional vector as the feature descriptor. Deep learning (DL), back propagation neural network (BP), and support vector machine (SVM) are applied to recognize the events respectively. BP has been proved to have a higher recognition rate compared to other methods. In order to implement the three algorithms, a data set is built which includes 150 samples of all kinds of events from the practical tests. Experiments show the effectiveness of the proposed methods.展开更多
Fluorescence lifetime imaging microscopy(FLIM)is a powerful tool to discriminate fluorescent molecules or probe their nanoscale environment.Traditionally,FLIM uses time-correlated single-photon counting(TCSPC),which i...Fluorescence lifetime imaging microscopy(FLIM)is a powerful tool to discriminate fluorescent molecules or probe their nanoscale environment.Traditionally,FLIM uses time-correlated single-photon counting(TCSPC),which is precise but intrinsically low-throughput due to its dependence on point detectors.Although time-gated cameras have demonstrated the potential for high-throughput FLIM in bright samples with dense labeling,their use in single-molecule microscopy has not been explored extensively.Here,we report fast and accurate single-molecule FLIM with a commercial time-gated single-photon camera.Our optimized acquisition scheme achieves single-molecule lifetime measurements with a precision only about three times less than TCSPC,while imaging with a large number of pixels(512×512)allowing for the spatial multiplexing of over 3000 molecules.With this approach,we demonstrate parallelized lifetime measurements of large numbers of labeled pore-forming proteins on supported lipid bilayers,and temporal single-molecule Förster resonance energy transfer measurements at 5-25 Hz.This method holds considerable promise for the advancement of multi-target single-molecule localization microscopy and biopolymer sequencing.展开更多
基金supported by the Pre-research Foundation under Grant No. G020104PJ09DZ0246
文摘A gated viewing laser radar has an excellent performance in underwater low light level imaging, and it also provides a viable solution to inhibit backscattering. In this paper, a gated viewing imaging system according to the demand for real-time imaging is presented, and then the simulation is used to analyze the performance of the real-time gated viewing system. The range accuracy performance is limited by the slice number, the width of gate, the delay time step, the initial delay time, as well as the system noise and atmospheric turbulence. The simulation results indicate that the highest range accuracy can be achieved when the system works with the optimal parameters. Finally, how to choose the optimal parameters has been researched.
文摘In this paper, the response time of all-optical AND logic gate using the triangular photonic crystal lattice is investigated. The proposed logic gate consists of a photonic crystal nano-resonator formed by changing the size of the dielectric rods. The structure benefits the interference effect mechanism. The contrast ratio of the photonic crystal AND logic gate is obtained as 6 d B. In addition to simplicity, the designed nano-resonator increases the bit rate of logic gate. The delay time and footprint of logic gate are respectively 0.32 ps and 146 μm2. The proposed photonic crystal AND logic gate can operate at a bit rate of 3.12 Tbit/s。
基金supported by the National High Technology Research and Development Program of China(Grant No.SS2015AA010601)the National Natural Science Foundation of China(Grant Nos.61176091 and 61306129)
文摘A multi-deposition multi-annealing technique （MDMA） is introduced into the process of high-k/metal gate MOSFET for the gate last process to effectively reduce the gate leakage and improve the device＇s performance. In this paper, we systematically investigate the electrical parameters and the time-dependent dielectric breakdown （TDDB） characteristics of positive channel metal oxide semiconductor （PMOS） under different MDMA process conditions, including the depo- sition/annealing （D＆A） cycles, the D＆A time, and the total annealing time. The results show that the increases of the number of D＆A cycles （from 1 to 2） and D＆A time （from 15 s to 30 s） can contribute to the results that the gate leakage current decreases by about one order of magnitude and that the time to fail （TTF） at 63.2% increases by about several times. However, too many D＆A cycles （such as 4 cycles） make the equivalent oxide thickness （EOT） increase by about 1A and the TTF of PMOS worsen. Moreover, different D＆A times and numbers of D＆A cycles induce different breakdown mechanisms.
文摘Purpose: Respiratory-gated radiation therapy (RT) using the real-time tumor-tracking radiotherapy (RTRT) system is an effective technique for managing tumor motion. High dosimetric and geometric accuracy is needed;however, quality assurance (QA) for respiratory-gated RT using the RTRT system has not been reported. The purpose of this study was to perform QA for respiratorygated RT using the RTRT system. Materials and Methods: The RTRT system detected the position of the fiducial marker and radiation delivery gated to the motion of the marker was performed. The dynamic anthropomorphic thorax phantom was positioned at the isocenter using the fiducial marker in the phantom. The phantom was irradiated only when the fiducial marker was within a three-dimensional gating window of ±2 mm from the planned position. First, the absolute doses were measured using anionization chamber inserted in the phantom under the stationary, gating and non-gating state for sinusoidal (nadir-to-peak amplitude [A]: 20 - 40 mm, breathing period [T]: 2 - 4 s) and the basic respiratory patterns. Second, the dose profiles were measured using Gafchromic films in the phantom under the same conditions. Differences between dose profiles were calculated to evaluate the dosimetric and geometric accuracy. Finally, differences between the actual and measured position of the fiducial marker were calculated to evaluate the tracking accuracy for sinusoidal and basic respiratory patterns. Results: For the sinusoidal patterns, the relative doses were 0.93 for non-gating and 0.99 for gating (A = 20 mm, T = 2 s), 0.94 for non-gating and 1.00 for gating (A = 20 mm, T = 4 s), 0.55 for non-gating and 1.00 for gating (A = 40 mm, T = 4 s), respectively. For the basic respiratory pattern, the relative doses were 1.00 for non-gating and 1.00 for gating, respectively. Compared to the stationary conditions, the differences in lateral distance between the 90% dose of dose profiles were 6.23 mm for non-gating and 0.36 mm for gating (A = 20 mm, T = 2 s), 8.79 mm for non-gating and 1.73 mm for gating (A = 20 mm, T = 4 s), 18.37 mm for non-gating and 0.67 mm for gating (A = 40 mm, T = 4 s), respectively. For the basic respiratory pattern, those were 5.23 mm for non-gating and 0.35 mm for gating. The root mean square (RMS) values of the tracking error were 0.18 mm (A = 20 mm, T = 2 s), 0.14 mm (A = 20 mm, T = 4 s), and 0.21 mm (A = 40 mm, T = 4 s) for sinusoidal and 0.79 mm for the basic respiratory pattern, respectively. Conclusion: We conducted QA for respiratory-gated RT using the RTRT system. The respiratory-gated RT using the RTRT system reduced the blurring effects on dose distribution with high dosimetric and geometric accuracy.
基金partially supported by the National Natural Science Foundation of China-Civil Aviation Joint Fund(Nos.U1533203,U1233124.)
文摘Long departure-taxi-out time leads to significant airport surface congestion, fuel-burn costs, and excessive emissions of greenhouse gases. To reduce these undesirable effects, a Predicted taxi-out time-based Dynamic Pushback Control(PDPC) method is proposed. The implementation of this method requires two steps: first, the taxi-out times for aircraft are predicted by the leastsquares support-vector regression approach of which the parameters are optimized by an introduced improved Firefly algorithm. Then, a dynamic pushback control model equipped with a linear gate-hold penalty function is built, along with a proposed iterative taxiway queue-threshold optimization algorithm for solving the model. A case study with data obtained from Beijing International airport(PEK) is presented. The taxi-out time prediction model achieves predictive accuracy within 3 min and 5 min by 84.71% and 95.66%, respectively. The results of the proposed pushback method show that total operation cost and fuel-burn cost achieve a 14.0% and 21.1%reduction, respectively, as compared to the traditional K-control policy.(3) From the perspective of implementation, using PDPC policy can significantly reduce the queue length in taxiway and taxi-out time. The total operation cost and fuel-burn cost can be curtailed by 37.2% and 52.1%,respectively, as compared to the non-enforcement of any pushback control mechanism. These results show that the proposed pushback control model can reduce fuel-burn costs and airport surface congestion effectively.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11275024,61274024,and 61474123)the Youth Innovation Promotion Association,China(Grant No.2013105)the Ministry of Science and Technology of China(Grant Nos.2013YQ030595-3 and 2011AA120101)
文摘We characterized the dependence of the timing jitter of an InGaAs/InP single-photon avalanche diode on the excess bias voltage（V（ex）） when operated in 1-GHz sinusoidally gated mode.The single-photon avalanche diode was cooled to-30 degrees Celsius.When the V（ex） is too low（0.2 V-0.8 V） or too high（3 V-4.2 V）,the timing jitter is increased with the V（ex）,particularly at high V（ex）.While at middle V（ex）（1 V-2.8 V）,the timing jitter is reduced.Measurements of the timing jitter of the same avalanche diode with pulsed gating show that this effect is likely related to the increase of both the amplitude of the V（ex） and the width of the gate-on time.For the 1-GHz sinusoidally gated detector,the best jitter of 93 ps is achieved with a photon detection efficiency of 21.4%and a dark count rate of -2.08×10 -5 per gate at the V（ex） of 2.8 V.To evaluate the whole performance of the detector,we calculated the noise equivalent power（NEP） and the afterpulse probability（P（ap））.It is found that both NEP and P（ap） increase quickly when the V（ex） is above 2.8 V.At -2.8-V V（ex）,the NEP and P（ap） are -2.06×10-（16）W/Hz-（1/2） and 7.11%,respectively.Therefore,the detector should be operated with V（ex） of 2.8 V to exploit the fast time response,low NEP and low P（ap）.
基金This project was supported by the National Natural Science Foundation of China(60135020) National Key Pre-researchProject of China(413010701 -3) .
文摘A novel reconfigurable hardware system which uses both muhi-DSP and FPGA to attain high performance and real-time image processing are presented. The system structure and working principle of mainly processing multi-BSP board, extended multi-DSP board are analysed. The outstanding advantage is that the communication among different board components of this system is supported by high speed link ports ＆ serial ports for increasing the system performance and computational power. Then the implementation of embedded real-time operating systems （RTOS） by us is discussed in detail. In this system, we adopt two kinds of parallel structures controlled by RTOS for parallel processing of algorithms. The experimental results show that exploitive period of the system is short, and maintenance convenient. Thus it is suitable for real-time image processing and can get satisfactory effect of image recognition.
基金This work was supported by the National Natural Science Foundation of China （Nos. 61227902, 61573343） and the National Center for Mathematics and Interdisciplinary Sciences, CAS.
文摘Fast and high fidelity quantum control is the key technology of quantum computing. The hybrid system composed of the nitrogen-vacancy center and nearby Carbon-13 nuclear spin is expected to solve this problem. The nitrogen-vacancy center electron spin enables fast operations for its strong coupling to the control field, whereas the nuclear spins preserve the coherence for their weak coupling to the environment. In this paper, we describe a strategy to achieve time-optimal control of the Carbon-13 nuclear spin qubit by alternating controlling the nitrogen-vacancy center electron spin as an actuator. We transform the qubit gate operation into a switched system. By using the maximum principle, we study the minimum time control of the switched system and obtain the time-optimal control of the qubit gate operation. We show that the X gate and Y gate operations are within 10μs while the fidelity reaches 0.995.
文摘Making events recognition more reliable under complex environment is one of the most important challenges for the intelligent recognition system to the ticket gate in the urban rapid rail transit. The motion objects passing through the ticket gate could be described as a series of moving sequences got by sensors that located in the walkway side of the ticket gate. This paper presents a robust method to detect some classes of events of ticket gate in the urban rapid rail transit. Diffused reflectance infrared sensors are used to collect signals. In this paper, the motion objects are here referred to passenger(s) or (and) luggage(s), for which are of frequent occurrences in the ticket gate of the urban railway traffic. Specifically, this paper makes two main contributions: 1) The proposed recognition method could be used to identify several events, including the event of one person passing through the ticket gate, the event of two consecutive passengers passing through the ticket gate without a big gap between them, and the event of a passenger walking through the ticket gate pulling a suitcase;2) The moving time sequence matrix is transformed into a one-dimensional vector as the feature descriptor. Deep learning (DL), back propagation neural network (BP), and support vector machine (SVM) are applied to recognize the events respectively. BP has been proved to have a higher recognition rate compared to other methods. In order to implement the three algorithms, a data set is built which includes 150 samples of all kinds of events from the practical tests. Experiments show the effectiveness of the proposed methods.
基金support from the EPFL Center for Imaging(A.R.,N.R.,E.C.and C.B.)European Research Council(grant 101020445 to A.R.)+2 种基金the Swiss National Science Foundation(grant 200021-184687 to G.P.A.,grant 200021L-212128 to M.D.P.and grant IZSEZ0-224299 to R.R.)the National Center of Competence in Research Bio-Inspired Materials(NCCR 51NF40-182881 to G.P.A.and A.R.)the European Union Program HORIZON-Pathfinder-Open(grant 101099125 to G.P.A.).
文摘Fluorescence lifetime imaging microscopy(FLIM)is a powerful tool to discriminate fluorescent molecules or probe their nanoscale environment.Traditionally,FLIM uses time-correlated single-photon counting(TCSPC),which is precise but intrinsically low-throughput due to its dependence on point detectors.Although time-gated cameras have demonstrated the potential for high-throughput FLIM in bright samples with dense labeling,their use in single-molecule microscopy has not been explored extensively.Here,we report fast and accurate single-molecule FLIM with a commercial time-gated single-photon camera.Our optimized acquisition scheme achieves single-molecule lifetime measurements with a precision only about three times less than TCSPC,while imaging with a large number of pixels(512×512)allowing for the spatial multiplexing of over 3000 molecules.With this approach,we demonstrate parallelized lifetime measurements of large numbers of labeled pore-forming proteins on supported lipid bilayers,and temporal single-molecule Förster resonance energy transfer measurements at 5-25 Hz.This method holds considerable promise for the advancement of multi-target single-molecule localization microscopy and biopolymer sequencing.
