The single-pixel imaging(SPI) technique is able to capture two-dimensional(2 D) images without conventional array sensors by using a photodiode. As a novel scheme, Fourier single-pixel imaging(FSI) has been proven cap...The single-pixel imaging(SPI) technique is able to capture two-dimensional(2 D) images without conventional array sensors by using a photodiode. As a novel scheme, Fourier single-pixel imaging(FSI) has been proven capable of reconstructing high-quality images. Due to the fact that the Fourier basis patterns(also known as grayscale sinusoidal patterns)cannot be well displayed on the digital micromirror device(DMD), a fast FSI system is proposed to solve this problem by binarizing Fourier pattern through a dithering algorithm. However, the traditional dithering algorithm leads to low quality as the extra noise is inevitably induced in the reconstructed images. In this paper, we report a better dithering algorithm to binarize Fourier pattern, which utilizes the Sierra–Lite kernel function by a serpentine scanning method. Numerical simulation and experiment demonstrate that the proposed algorithm is able to achieve higher quality under different sampling ratios.展开更多
Dithering optimization techniques can be divided into the phase-optimized technique and the intensity-optimized technique. The problem with the former is the poor sensitivity to various defocusing amounts, and the pro...Dithering optimization techniques can be divided into the phase-optimized technique and the intensity-optimized technique. The problem with the former is the poor sensitivity to various defocusing amounts, and the problem with the latter is that it cannot enhance phase quality directly nor efficiently. In this paper, we present a multi-objective optimization framework for three-dimensional(3D) measurement by utilizing binary defocusing technique. Moreover, a binary patch optimization technique is used to solve the time-consuming issue of genetic algorithm. It is demonstrated that the presented technique consistently obtains significant phase performance improvement under various defocusing amounts.展开更多
This paper proposes a generation method of dithering signal based on Discrete Fourier Transform (DFT), which is not only independent with the input signal but also can decrease the quantization error of the Analog-to-...This paper proposes a generation method of dithering signal based on Discrete Fourier Transform (DFT), which is not only independent with the input signal but also can decrease the quantization error of the Analog-to-Digital Converter (ADC). A detailed investigation of three typical dithering effects on the quantization error in ADC has been also presented in this paper, to highlight the advantages of the proposed reconstructed dithering signal. The simulation experiment and theoretical analysis illustrate that the reconstructed dithering signal based on DFT can improve the performance of ADC in comparison with traditional typical dithering signal.展开更多
Most of the existing physical layer watermarking authentication schemes are based on a single-input single-output system and require pre-issue of shared keys.To address these problems,in this thesis,a physical layer a...Most of the existing physical layer watermarking authentication schemes are based on a single-input single-output system and require pre-issue of shared keys.To address these problems,in this thesis,a physical layer authentication scheme without the distribution keys is proposed based on the constellation dithering physical layer authentication watermarking mechanism with a multiple-input multiple-output(MIMO)system,and space-time block coding(STBC)is used to improve the robustness of transmission.Specifically,the legitimate node obtains channel state information(CSI)through channel probing and couples CSI with the message signal using a hash function to generate an authentication tag,which is then embedded through constellation dithering.The receiver extracts the tag and authenticates it using hypothesis testing.Performance analysis shows that the scheme is resistant to various attacks such as replay,interference,tampering,and forgery.Simulation results show that the use of MIMO multi-antenna diversity with STBC coding technique reduces the bit error rate(BER)of message signals and tag signals and improves the detection rate of legitimate signals.展开更多
This article proposes a creative brightness average method to improve the traditional dithering algorithm for super twisted nematic-liquid crystal display （STN-LCD）. This method restrains the flicker and crosstalk p...This article proposes a creative brightness average method to improve the traditional dithering algorithm for super twisted nematic-liquid crystal display （STN-LCD）. This method restrains the flicker and crosstalk phenomena by avoiding the simultaneous turning on or turning off between adjacent pixels in the same frame. It costs little hardware to realize the brightness average circuit in the liquid crystal display （LCD） controller, without increasing the complexity of STN-LCD driver circuit. The experimental results show that when the frame frequency is 60 Hz, the monochrome image adds up to 64 gray levels, while the multicolor image adds up to 64^3= 262 144 colors. Meanwhile, the power consumption of the prototype is only 3 317 mW. In short, the brightness average circuit can restrain the phenomena of flicker in high efficiency, and can remarkedly improve the gray and multicolor effect for STN-LCD without increasing the frame frequency, which leads to an apparent decrease in the power consumption.展开更多
Beyond-5G(B5G)aims to meet the growing demands of mobile traffic and expand the communication space.Considering that intelligent applications to B5G wireless communications will involve security issues regarding user ...Beyond-5G(B5G)aims to meet the growing demands of mobile traffic and expand the communication space.Considering that intelligent applications to B5G wireless communications will involve security issues regarding user data and operational data,this paper analyzes the maximum capacity of the multi-watermarking method for multimedia signal hiding as a means of alleviating the information security problem of B5G.The multiwatermarking process employs spread transform dither modulation.During the watermarking procedure,Gram-Schmidt orthogonalization is used to obtain the multiple spreading vectors.Consequently,multiple watermarks can be simultaneously embedded into the same position of a multimedia signal.Moreover,the multiple watermarks can be extracted without affecting one another during the extraction process.We analyze the effect of the size of the spreading vector on the unit maximum capacity,and consequently derive the theoretical relationship between the size of the spreading vector and the unit maximum capacity.A number of experiments are conducted to determine the optimal parameter values for maximum robustness on the premise of high capacity and good imperceptibility.展开更多
Digital image stabilization technique plays important roles in video surveillance and object acquisition.Many useful electronic image stabilization algorithms have been studied.A real-time algorithm is proposed based ...Digital image stabilization technique plays important roles in video surveillance and object acquisition.Many useful electronic image stabilization algorithms have been studied.A real-time algorithm is proposed based on field image gray projection which enables the regional odd and even field image to be projected into x and y directions and thus to get the regional gray projection curves in x and y directions,respectively.For the odd field image channel,motion parameters can be estimated via iterative minimum absolute difference based on two successive field image regional gray projection curves.Then motion compensations can be obtained after using the Kalman filter method.Finally,the odd field image is adjusted according to the compensations.In the mean time,motion compensation is applied to the even field image channel with the odd field image gray projection curves of the current frame.By minimizing absolute difference between odd and even field image gray projection curves of the current frame,the inter-field motion parameters can be estimated.Therefore,the even field image can be adjusted by combining the inter-field motion parameters and the odd field compensations.Finally,the stabilized image sequence can be obtained by synthesizing the adjusted odd and even field images.Experimental results show that the proposed algorithm can run in real-time and have a good stabilization performance.In addition,image blurring can be improved.展开更多
As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode （H-mode） with low heating power will be a critical issue. In the recent experiment on EAST, the ...As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode （H-mode） with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive （LHCD） wave only. Reciprocating Langmuir probe measurements at the outer midplane showed that the electron density ne and electron tempel：ature Te in the scrape-off layer （SOL） were significantly reduced in the ELM-free phase, resulting in the increase of lower-hybrid wave （LHW） reflection. It was found that the power loss Ploss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Da emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L-H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential （Vf） had negative spikes corresponding with the Da signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots, dithering was observed just before the L-H transition.展开更多
Color image printing technique on ink jetting printer is introduced.Color shading method such as dithering,Amplitude Modulation(AM)screening and Frequency Modulation(FM)screening is presented.Some solutions to the pro...Color image printing technique on ink jetting printer is introduced.Color shading method such as dithering,Amplitude Modulation(AM)screening and Frequency Modulation(FM)screening is presented.Some solutions to the problems with FM screening are given. An application program under Windows is developed.展开更多
A method is proposed to solve the problem of direction discrimination for laser feedback interferometers. By vibrating the feedback mirror with a small-amplitude and high-frequency sine wave, laser intensity is modula...A method is proposed to solve the problem of direction discrimination for laser feedback interferometers. By vibrating the feedback mirror with a small-amplitude and high-frequency sine wave, laser intensity is modulated accordingly. The modulation amplitude can be extracted using a phase sensitive detector （PSD）. When the feedback mirror moves, the PSD output shows a quasi-sine waveform similar to a laser intensity interference fringe but with a phase difference of approximately ±π/2. If the movement direction of the feedback mirror changes, the phase difference sign reverses. Therefore, the laser feedback interferometer offers a potential application in displacement measurement with a resolution of 1/8 wavelength and in-time direction discrimination. Without using optical components such as polarization beam splitters and wave plates, the interferometer is very simple, easy to align, and less costly.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61271376)the Anhui Provincial Natural Science Foundation,China(Grant No.1208085MF114)
文摘The single-pixel imaging(SPI) technique is able to capture two-dimensional(2 D) images without conventional array sensors by using a photodiode. As a novel scheme, Fourier single-pixel imaging(FSI) has been proven capable of reconstructing high-quality images. Due to the fact that the Fourier basis patterns(also known as grayscale sinusoidal patterns)cannot be well displayed on the digital micromirror device(DMD), a fast FSI system is proposed to solve this problem by binarizing Fourier pattern through a dithering algorithm. However, the traditional dithering algorithm leads to low quality as the extra noise is inevitably induced in the reconstructed images. In this paper, we report a better dithering algorithm to binarize Fourier pattern, which utilizes the Sierra–Lite kernel function by a serpentine scanning method. Numerical simulation and experiment demonstrate that the proposed algorithm is able to achieve higher quality under different sampling ratios.
基金Project supported by the Zhejiang Provincial Welfare Technology Applied Research Project,China(Grant No.2017C31080)
文摘Dithering optimization techniques can be divided into the phase-optimized technique and the intensity-optimized technique. The problem with the former is the poor sensitivity to various defocusing amounts, and the problem with the latter is that it cannot enhance phase quality directly nor efficiently. In this paper, we present a multi-objective optimization framework for three-dimensional(3D) measurement by utilizing binary defocusing technique. Moreover, a binary patch optimization technique is used to solve the time-consuming issue of genetic algorithm. It is demonstrated that the presented technique consistently obtains significant phase performance improvement under various defocusing amounts.
文摘This paper proposes a generation method of dithering signal based on Discrete Fourier Transform (DFT), which is not only independent with the input signal but also can decrease the quantization error of the Analog-to-Digital Converter (ADC). A detailed investigation of three typical dithering effects on the quantization error in ADC has been also presented in this paper, to highlight the advantages of the proposed reconstructed dithering signal. The simulation experiment and theoretical analysis illustrate that the reconstructed dithering signal based on DFT can improve the performance of ADC in comparison with traditional typical dithering signal.
基金supported by the National Key Research and Development Program of China(No.2017YFE0135700)the High Level Talent Support Project of Hebei Province(No.A201903011)+3 种基金the Natural Science Foundation of Hebei Province(No.F2018209358)the Tsinghua Precision Medicine Foundation(No.2022TS003)the Ministry of Education and Science(MES)for NCDSC,part of the Bulgarian National Roadmap on RIs(No.D01-387/18.12.2020)the Telecommunications Research Centre(TRC)of University of Limerick,Ireland.
文摘Most of the existing physical layer watermarking authentication schemes are based on a single-input single-output system and require pre-issue of shared keys.To address these problems,in this thesis,a physical layer authentication scheme without the distribution keys is proposed based on the constellation dithering physical layer authentication watermarking mechanism with a multiple-input multiple-output(MIMO)system,and space-time block coding(STBC)is used to improve the robustness of transmission.Specifically,the legitimate node obtains channel state information(CSI)through channel probing and couples CSI with the message signal using a hash function to generate an authentication tag,which is then embedded through constellation dithering.The receiver extracts the tag and authenticates it using hypothesis testing.Performance analysis shows that the scheme is resistant to various attacks such as replay,interference,tampering,and forgery.Simulation results show that the use of MIMO multi-antenna diversity with STBC coding technique reduces the bit error rate(BER)of message signals and tag signals and improves the detection rate of legitimate signals.
文摘This article proposes a creative brightness average method to improve the traditional dithering algorithm for super twisted nematic-liquid crystal display （STN-LCD）. This method restrains the flicker and crosstalk phenomena by avoiding the simultaneous turning on or turning off between adjacent pixels in the same frame. It costs little hardware to realize the brightness average circuit in the liquid crystal display （LCD） controller, without increasing the complexity of STN-LCD driver circuit. The experimental results show that when the frame frequency is 60 Hz, the monochrome image adds up to 64 gray levels, while the multicolor image adds up to 64^3= 262 144 colors. Meanwhile, the power consumption of the prototype is only 3 317 mW. In short, the brightness average circuit can restrain the phenomena of flicker in high efficiency, and can remarkedly improve the gray and multicolor effect for STN-LCD without increasing the frame frequency, which leads to an apparent decrease in the power consumption.
基金funded by The National Natural Science Foundation of China under Grant(No.62273108,62306081)The Youth Project of Guangdong Artificial Intelligence and Digital Economy Laboratory(Guangzhou)(PZL2022KF0006)+3 种基金The National Key Research and Development Program of China(2022YFB3604502)Special Fund Project of GuangzhouScience and Technology Innovation Development(202201011307)Guangdong Province Industrial Internet Identity Analysis and Construction Guidance Fund Secondary Node Project(1746312)Special Projects in Key Fields of General Colleges and Universities in Guangdong Province(2021ZDZX1016).
文摘Beyond-5G(B5G)aims to meet the growing demands of mobile traffic and expand the communication space.Considering that intelligent applications to B5G wireless communications will involve security issues regarding user data and operational data,this paper analyzes the maximum capacity of the multi-watermarking method for multimedia signal hiding as a means of alleviating the information security problem of B5G.The multiwatermarking process employs spread transform dither modulation.During the watermarking procedure,Gram-Schmidt orthogonalization is used to obtain the multiple spreading vectors.Consequently,multiple watermarks can be simultaneously embedded into the same position of a multimedia signal.Moreover,the multiple watermarks can be extracted without affecting one another during the extraction process.We analyze the effect of the size of the spreading vector on the unit maximum capacity,and consequently derive the theoretical relationship between the size of the spreading vector and the unit maximum capacity.A number of experiments are conducted to determine the optimal parameter values for maximum robustness on the premise of high capacity and good imperceptibility.
基金supported by the National Natural Science Foundation of China(6110118561302145)
文摘Digital image stabilization technique plays important roles in video surveillance and object acquisition.Many useful electronic image stabilization algorithms have been studied.A real-time algorithm is proposed based on field image gray projection which enables the regional odd and even field image to be projected into x and y directions and thus to get the regional gray projection curves in x and y directions,respectively.For the odd field image channel,motion parameters can be estimated via iterative minimum absolute difference based on two successive field image regional gray projection curves.Then motion compensations can be obtained after using the Kalman filter method.Finally,the odd field image is adjusted according to the compensations.In the mean time,motion compensation is applied to the even field image channel with the odd field image gray projection curves of the current frame.By minimizing absolute difference between odd and even field image gray projection curves of the current frame,the inter-field motion parameters can be estimated.Therefore,the even field image can be adjusted by combining the inter-field motion parameters and the odd field compensations.Finally,the stabilized image sequence can be obtained by synthesizing the adjusted odd and even field images.Experimental results show that the proposed algorithm can run in real-time and have a good stabilization performance.In addition,image blurring can be improved.
基金supported by the National Magnetic Confinement Fusion Science Program of China (No. 2011GB107001)National Natural Science Foundation of China (Nos. 11075181, 10725523, 10721505, 10990212, 10605028)the ITER project of China (No. 2010GB104001)
文摘As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode （H-mode） with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive （LHCD） wave only. Reciprocating Langmuir probe measurements at the outer midplane showed that the electron density ne and electron tempel：ature Te in the scrape-off layer （SOL） were significantly reduced in the ELM-free phase, resulting in the increase of lower-hybrid wave （LHW） reflection. It was found that the power loss Ploss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Da emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L-H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential （Vf） had negative spikes corresponding with the Da signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots, dithering was observed just before the L-H transition.
文摘Color image printing technique on ink jetting printer is introduced.Color shading method such as dithering,Amplitude Modulation(AM)screening and Frequency Modulation(FM)screening is presented.Some solutions to the problems with FM screening are given. An application program under Windows is developed.
文摘A method is proposed to solve the problem of direction discrimination for laser feedback interferometers. By vibrating the feedback mirror with a small-amplitude and high-frequency sine wave, laser intensity is modulated accordingly. The modulation amplitude can be extracted using a phase sensitive detector （PSD）. When the feedback mirror moves, the PSD output shows a quasi-sine waveform similar to a laser intensity interference fringe but with a phase difference of approximately ±π/2. If the movement direction of the feedback mirror changes, the phase difference sign reverses. Therefore, the laser feedback interferometer offers a potential application in displacement measurement with a resolution of 1/8 wavelength and in-time direction discrimination. Without using optical components such as polarization beam splitters and wave plates, the interferometer is very simple, easy to align, and less costly.
