A mean-match correlation vector quantizer (MMCVQ) was presented for fast image encoding. In this algorithm, a sorted codebook is generated regarding the mean values of all codewords. During the encoding stage, high co...A mean-match correlation vector quantizer (MMCVQ) was presented for fast image encoding. In this algorithm, a sorted codebook is generated regarding the mean values of all codewords. During the encoding stage, high correlation of the adjacent image blocks is utilized, and a searching range is obtained in the sorted codebook according to the mean value of the current processing vector. In order to gain good performance, proper THd and NS are predefined on the basis of experimental experiences and additional distortion limitation. The expermental results show that the MMCVQ algorithm is much faster than the full-search VQ algorithm, and the encoding quality degradation of the proposed algorithm is only 0.3~0.4 dB compared to the full-search VQ.展开更多
With the advancements in nuclear energy,methods that can accurately obtain the spatial information of radioactive sources have become essential for nuclear energy safety.Coded aperture imaging technology is widely use...With the advancements in nuclear energy,methods that can accurately obtain the spatial information of radioactive sources have become essential for nuclear energy safety.Coded aperture imaging technology is widely used because it provides two-dimensional distribution information of radioactive sources.The coded array is a major component of a coded aperture gamma camera,and it affects the key performance parameters of the camera.Currently,commonly used coded arrays such as uniformly redundant arrays(URAs)and modified uniformly redundant arrays(MURAs)have prime numbers of rows or columns and may lead to wastage of detector pixels.A 16×16 coded array was designed on the basis of an existing 16×16 multi-pixel position-sensitive cadmium zinc telluride detector.The digital signal-to-noise(SNR)ratio of the point spread function at the center of the array is 25.67.Furthermore,Monte Carlo camera models and experimental devices based on rank-13 MURA and rank-16 URA have been constructed.With the same angular resolution,the field size of view under rank-16 URA is 1.53 times that of under rank-13 MURA.Simulations(Am-241,Co-57,Ir-192,Cs-137)and experiments(Co-57)are conducted to compare the imaging performance between rank-16 URA and rank-13 MURA.The contrast-to-noise ratio of the reconstructed image of the rank-16 array is great and only slightly lower than that of rank-13 MURA.However,as the photon energy increases,the gap becomes almost negligible.展开更多
Narrative design was originated in the 20th century.As a kind of design thinking,it runs through various fields such as architecture,environment,and new media.The QR code design has gradually become a bridge for media...Narrative design was originated in the 20th century.As a kind of design thinking,it runs through various fields such as architecture,environment,and new media.The QR code design has gradually become a bridge for media integration design,and its importance is becoming increasingly obvious.An optimized QR code design may gradually replace the original LOGO of certain goods or brand.In this study,narration is embedded into the QR code design,and a new QR code design image is gradually constructed through three ways of planarization,spatialization,and narration.展开更多
In this article we propose a four-level rubidium(Rb87)atomic system for observing interesting features of polarization state rotation in a fast light medium.We investigate spontaneously generated coherence(SGC)for a s...In this article we propose a four-level rubidium(Rb87)atomic system for observing interesting features of polarization state rotation in a fast light medium.We investigate spontaneously generated coherence(SGC)for a spinning medium.We show how SGC can affect different spectral profiles of the polarization state and images in this suggested model.We observe a 0.5 radian rotation and 2.5 microsecond time advancement in our proposed system.Our precise results will provide a new platform for researchers in quantum optics due to its applications in image coding,telecommunications and cloaking technology.展开更多
Coded aperture imaging(CAI)is a technique to image three-dimensional scenes with special controlled abilities.In this review,we survey several recently proposed techniques to control the parameters of CAI by engineeri...Coded aperture imaging(CAI)is a technique to image three-dimensional scenes with special controlled abilities.In this review,we survey several recently proposed techniques to control the parameters of CAI by engineering the aperture of the system.The prime architectures of these indirect methods of imaging are reviewed.For each design,we mention the relevant application of the CAI recorders and summarize this overview with a general perspective on this research topic.展开更多
The development of laser systems leads to an increasing threat to photoelectric imaging sensors.A cubic phase plate wavefront coding imaging system is proposed to reduce the risk of damage owing to intense laser radia...The development of laser systems leads to an increasing threat to photoelectric imaging sensors.A cubic phase plate wavefront coding imaging system is proposed to reduce the risk of damage owing to intense laser radiation.Based on the wavefront coding imaging model,the diffracted spot profile and the light intensity distribution on the observation plane are simulated.An experimental device is set up to measure the laser-induced damage thresholds and investigate the morphology of laser-induced damage patterns of the conventional and the wavefront encoding imaging system.Simulations and experimental results manifest the superior laser suppression performance of the proposed method,which can help diminish the undesirable effects of laser irradiation on an imaging sensor.展开更多
Purpose Fast neutrons and gamma-ray imaging detection is an effective way to detect and identify radioactive material in the field of nuclear security.A compact coded aperture imaging(CAI)camera was designed to be sen...Purpose Fast neutrons and gamma-ray imaging detection is an effective way to detect and identify radioactive material in the field of nuclear security.A compact coded aperture imaging(CAI)camera was designed to be sensitive to both gamma and neutron radiation based on plastic scintillators and multi-pixel photon counters(MPPC).Methods MPPCs coupling with the 13×13 pixelated plastic scintillators one-to-one were utilized to reduce the scale of the CAI system while maintaining good positional performance.The symmetric charge division(SCD)circuit was adopted to reduce the 169 signals output from the MPPC array to 26.Each waveform was collected and processed with four Domino Ring Sampler 4(DRS4)chips and two 16-channel analog-to-digital converter(ADC)modules.As the pulse shapes of fast neutrons would be broadened after elastic scattering multiple times in the scintillators,the Anger-Logic method was applied to eliminate multiple elastic scattering events so that good pulse shape discrimination(PSD)performance can be achieved.Results The imaging and detection ability of the camerawas evaluated using the 241Am-Be(5.9×10^(5) n/s)neutron source and 137Cs(370 MBq)gammasource.The camera can be used to detect fast neutrons(0.5–10 MeV)and gammarays(0.2–2.5MeV).Furthermore,it can implement efficient neutron/gamma PSD capabilities in the mixed-field environment.The figure of merit(FOM)of the camera calculated at 400keVee energy cut is 0.93.Conclusion A compact MPPC-based CAI camera was designed to detect and discriminate fast neutrons and gamma rays.Its good PSD performance was well suited to distinguish fast neutrons from gamma rays in a dual-particle environment.The portable design makes it promising for complex monitoring scenarios in nuclear security.展开更多
文摘A mean-match correlation vector quantizer (MMCVQ) was presented for fast image encoding. In this algorithm, a sorted codebook is generated regarding the mean values of all codewords. During the encoding stage, high correlation of the adjacent image blocks is utilized, and a searching range is obtained in the sorted codebook according to the mean value of the current processing vector. In order to gain good performance, proper THd and NS are predefined on the basis of experimental experiences and additional distortion limitation. The expermental results show that the MMCVQ algorithm is much faster than the full-search VQ algorithm, and the encoding quality degradation of the proposed algorithm is only 0.3~0.4 dB compared to the full-search VQ.
基金supported by the National Natural Science Foundation of China(No.11675078)the Primary Research and Development Plan of Jiangsu Province(No.BE2017729)the Foundation of Graduate Innovation Center in NUAA(No.kfjj20190614)。
文摘With the advancements in nuclear energy,methods that can accurately obtain the spatial information of radioactive sources have become essential for nuclear energy safety.Coded aperture imaging technology is widely used because it provides two-dimensional distribution information of radioactive sources.The coded array is a major component of a coded aperture gamma camera,and it affects the key performance parameters of the camera.Currently,commonly used coded arrays such as uniformly redundant arrays(URAs)and modified uniformly redundant arrays(MURAs)have prime numbers of rows or columns and may lead to wastage of detector pixels.A 16×16 coded array was designed on the basis of an existing 16×16 multi-pixel position-sensitive cadmium zinc telluride detector.The digital signal-to-noise(SNR)ratio of the point spread function at the center of the array is 25.67.Furthermore,Monte Carlo camera models and experimental devices based on rank-13 MURA and rank-16 URA have been constructed.With the same angular resolution,the field size of view under rank-16 URA is 1.53 times that of under rank-13 MURA.Simulations(Am-241,Co-57,Ir-192,Cs-137)and experiments(Co-57)are conducted to compare the imaging performance between rank-16 URA and rank-13 MURA.The contrast-to-noise ratio of the reconstructed image of the rank-16 array is great and only slightly lower than that of rank-13 MURA.However,as the photon energy increases,the gap becomes almost negligible.
文摘Narrative design was originated in the 20th century.As a kind of design thinking,it runs through various fields such as architecture,environment,and new media.The QR code design has gradually become a bridge for media integration design,and its importance is becoming increasingly obvious.An optimized QR code design may gradually replace the original LOGO of certain goods or brand.In this study,narration is embedded into the QR code design,and a new QR code design image is gradually constructed through three ways of planarization,spatialization,and narration.
文摘In this article we propose a four-level rubidium(Rb87)atomic system for observing interesting features of polarization state rotation in a fast light medium.We investigate spontaneously generated coherence(SGC)for a spinning medium.We show how SGC can affect different spectral profiles of the polarization state and images in this suggested model.We observe a 0.5 radian rotation and 2.5 microsecond time advancement in our proposed system.Our precise results will provide a new platform for researchers in quantum optics due to its applications in image coding,telecommunications and cloaking technology.
基金Australian Research Council(LP190100505).European Union's Horizon 2020 research and innovation programme under grant agreement No.857627(CIPHR).
文摘Coded aperture imaging(CAI)is a technique to image three-dimensional scenes with special controlled abilities.In this review,we survey several recently proposed techniques to control the parameters of CAI by engineering the aperture of the system.The prime architectures of these indirect methods of imaging are reviewed.For each design,we mention the relevant application of the CAI recorders and summarize this overview with a general perspective on this research topic.
基金supported by the Technology Domain Fund of 173 Project(Nos.2021-JCJQ-JJ-0284 and 2022-JCJQ-JJ-0237)the Research Project of National University of Defense Technology(No.ZK20-41)+3 种基金the Advanced Laser Technology Laboratory Foundation of Anhui Province(No.AHL2021QN03)the CAST Creative Foundation(No.1020J20210117)the Anhui Provincial Natural Science Foundation(No.1908085MF199)the Young Doctor’s Fund of Electronic Countermeasure College of National University of Defense Technology(No.KY21C218)。
文摘The development of laser systems leads to an increasing threat to photoelectric imaging sensors.A cubic phase plate wavefront coding imaging system is proposed to reduce the risk of damage owing to intense laser radiation.Based on the wavefront coding imaging model,the diffracted spot profile and the light intensity distribution on the observation plane are simulated.An experimental device is set up to measure the laser-induced damage thresholds and investigate the morphology of laser-induced damage patterns of the conventional and the wavefront encoding imaging system.Simulations and experimental results manifest the superior laser suppression performance of the proposed method,which can help diminish the undesirable effects of laser irradiation on an imaging sensor.
基金the MajorDeployment Projects of Chinese Academy of Sciences(Grant Number ZDRWCN-2018-1-01)the Research Equipment Development Project of Chinese Academy of Sciences(Grant Number YZ201415).
文摘Purpose Fast neutrons and gamma-ray imaging detection is an effective way to detect and identify radioactive material in the field of nuclear security.A compact coded aperture imaging(CAI)camera was designed to be sensitive to both gamma and neutron radiation based on plastic scintillators and multi-pixel photon counters(MPPC).Methods MPPCs coupling with the 13×13 pixelated plastic scintillators one-to-one were utilized to reduce the scale of the CAI system while maintaining good positional performance.The symmetric charge division(SCD)circuit was adopted to reduce the 169 signals output from the MPPC array to 26.Each waveform was collected and processed with four Domino Ring Sampler 4(DRS4)chips and two 16-channel analog-to-digital converter(ADC)modules.As the pulse shapes of fast neutrons would be broadened after elastic scattering multiple times in the scintillators,the Anger-Logic method was applied to eliminate multiple elastic scattering events so that good pulse shape discrimination(PSD)performance can be achieved.Results The imaging and detection ability of the camerawas evaluated using the 241Am-Be(5.9×10^(5) n/s)neutron source and 137Cs(370 MBq)gammasource.The camera can be used to detect fast neutrons(0.5–10 MeV)and gammarays(0.2–2.5MeV).Furthermore,it can implement efficient neutron/gamma PSD capabilities in the mixed-field environment.The figure of merit(FOM)of the camera calculated at 400keVee energy cut is 0.93.Conclusion A compact MPPC-based CAI camera was designed to detect and discriminate fast neutrons and gamma rays.Its good PSD performance was well suited to distinguish fast neutrons from gamma rays in a dual-particle environment.The portable design makes it promising for complex monitoring scenarios in nuclear security.