A new feature based on higher order statistics is proposed for classification of MPSKsignals, which is invariant with respect to translation (shift), scale and rotation transforms of MPSK signal constellations, and ca...A new feature based on higher order statistics is proposed for classification of MPSKsignals, which is invariant with respect to translation (shift), scale and rotation transforms of MPSK signal constellations, and can suppress additive color or white Gaussian noise. Application of the new feature to classification of MPSK signals, at medium signal-to-noise ratio with specified sample size, results in high probability of correct identification. Finally, computer simulations and comparisons with existing algorithms are given.展开更多
A hybrid carrier（HC） scheme based on weighted-type fractional Fourier transform（WFRFT） has been proposed recently.While most of the works focus on HC scheme＇s inherent characteristics, little attention is paid to...A hybrid carrier（HC） scheme based on weighted-type fractional Fourier transform（WFRFT） has been proposed recently.While most of the works focus on HC scheme＇s inherent characteristics, little attention is paid to the WFRFT modulation recognition.In this paper, a new theory is provided to recognize the WFRFT modulation based on higher order cumulants（HOC）. First, it is deduced that the optimal WFRFT received order can be obtained through the minimization of 4 th-order cumulants, C_（42）. Then, a combinatorial searching algorithm is designed to minimize C_（42）.Finally, simulation results show that the designed scheme has a high recognition rate and the combinatorial searching algorithm is effective and reliable.展开更多
Background:The aim of this review is to summarize the optical quality results in patients following the implantation of the V4c implantable collamer lens with a central port(ICL,STAAR Surgical Inc.).Main text:A litera...Background:The aim of this review is to summarize the optical quality results in patients following the implantation of the V4c implantable collamer lens with a central port(ICL,STAAR Surgical Inc.).Main text:A literature search in several databases was carried out to identify those publications,both prospective,retrospective and/or comparative with other refractive surgery procedures,reporting optical outcomes of patients who were implanted with the V4c ICL model.A total of 17 clinical studies published between 2012 and 2021 were included in this review.A detailed analysis of the available data was performed including number of eyes,follow-up and preoperative spherical equivalent.Specifically,the review focused on several optical parameters including higher-order aberrations(HOAs),modulation transfer function(MTF)cut-off frequency and Strehl ratio.This review encompassed a total of 817 eyes measured using different optical devices based on Hartmann-Shack,retinal image quality measurement and ray-tracing technologies at different follow-ups.Conclusions:The outcomes found in this review lead us to conclude that the ICL V4c model provides good optical quality,by means of different metrics,when implanted.展开更多
We propose a neural network equalization delta-sigma modulation(DSM)technique.After performing DSM on the multiorder quadrature amplitude modulation(QAM)orthogonal frequency division multiplexing(OFDM)signal at the tr...We propose a neural network equalization delta-sigma modulation(DSM)technique.After performing DSM on the multiorder quadrature amplitude modulation(QAM)orthogonal frequency division multiplexing(OFDM)signal at the transmitting end,neural network equalizer technology is used in the digital signal processing at receiving end.Applying this technology to a 4.6 km W-band millimeter wave system,it is possible to achieve a 1 Gbaud 8192-QAM OFDM signal transmission.The data rate reached 23.4 Gbit/s with the bit error rate at 3.8×10^(-2),lower than soft-decision forward-error correction threshold(4×10^(-2)).展开更多
This paper presents a joint high order statistics （HOS） and signal-to-noise ratio （SNR） algorithm for the recognition of multiple-input multiple-output （MIMO） radar signal without a priori knowledge of the signa...This paper presents a joint high order statistics （HOS） and signal-to-noise ratio （SNR） algorithm for the recognition of multiple-input multiple-output （MIMO） radar signal without a priori knowledge of the signal parameters. This method is capable of recognizing the MIMO radar signal as well as discriminating it from single-carrier signal adopted by conventional radar. Meanwhile, the sub-carrier number of the none-coding MIMO radar signal is estimated. Extensive simulations are carried out in different operating conditions. Simulation results prove the feasibility and indicate that the recognition probability could reach over 90% when the value of SNR is above 0 dB.展开更多
This paper investigates the effects of walk-off among optical pulses on cross-phase modulation induced modulation instability in the normal dispersion region of an optical fibre with high-order dispersion. The results...This paper investigates the effects of walk-off among optical pulses on cross-phase modulation induced modulation instability in the normal dispersion region of an optical fibre with high-order dispersion. The results indicate that, in the case of high-order dispersion, the walk-off effect takes on new characteristics and will influence considerably the shape, position and especially the number of the spectral regions of the gain spectra of modulation instability. Not only the group-velocity mismatch, but also the difference of the third-order dispersion of two optical waves will alter the gain spectra of modulation instability but in different ways. Depending on the values of the walk-off parameters, the number of the spectral regions may increase from two to at most four, and the spectral shape and position may change too.展开更多
The electromagnetically induced grating effect in thermal and cold atoms has been studied theoretically. Studies have shown that, by adjusting the parameters, the first-order diffraction efficiency of the probe beam i...The electromagnetically induced grating effect in thermal and cold atoms has been studied theoretically. Studies have shown that, by adjusting the parameters, the first-order diffraction efficiency of the probe beam in the cold atomic system and the thermal atomic system is 34% and 31%, respectively, which is very close to the ideal diffraction efficiency of the sinusoidal grating. However, it is more difficult to prepare the cold atomic system than to prepare the thermal atomic system in the practical application, so the study of the electromagnetically induced grating effect in the thermal atomic system may be helpful for practical applications.展开更多
The pulse-width-modulated(PWM)current-source converters(CSCs)fed electric machine systems can be considered as a type of high reliability energy conversion systems,since they work with the long-life DC-link inductor a...The pulse-width-modulated(PWM)current-source converters(CSCs)fed electric machine systems can be considered as a type of high reliability energy conversion systems,since they work with the long-life DC-link inductor and offer high fault-tolerant capability for short-circuit faults.Besides,they provide motor friendly waveforms and four-quadrant operation ability.Therefore,they are suitable for high-power applications of fans,pumps,compressors and wind power generation.The purpose of this paper is to comprehensively review recent developments of key technologies on modulation and control of high-power(HP)PWM-CSC fed electric machines systems,including reduction of low-order current harmonics,suppression of inductor–capacitor(LC)resonance,mitigation of common-mode voltage(CMV)and control of modular PWM-CSC fed systems.In particular,recent work on the overlapping effects during commutation,LC resonance suppression under fault-tolerant operation and collaboration of modular PMW-CSCs are described.Both theoretical analysis and some results in simulations and experiments are presented.Finally,a brief discussion regarding the future trend of the HP CSC fed electric machines systems is presented.展开更多
This paper mainly studies the data characteristics of high order cumulants using digitally modulated signals, and constructs the identification feature parameters that can distinguish the signal modulation type by the...This paper mainly studies the data characteristics of high order cumulants using digitally modulated signals, and constructs the identification feature parameters that can distinguish the signal modulation type by the high-order cumulants data of the digital modulation signal. Set the identification signal modulation type determination threshold based on the value of the identification feature parameter. The identification feature parameter value of the signal modulation type is compared with the set determination threshold, to realize the recognition of digital modulation signal. This identification method is implemented based on MATLAB design, with a 2ASK (2-ary Amplitude Shift Keying) signal, 4ASK (4-ary Amplitude Shift Keying) signal, 2PSK (2-ary Phase Shift Keying) signal, 4PSK (4-ary Phase Shift Keying) signal, 2FSK (2-ary Frequency Shift Keying) signal, 4FSK (4-ary Frequency Shift Keying) signal. The second, fourth and sixth order cumulants of the six signals were analyzed. Calculate the selected identification feature parameter value and the determination threshold to identify the six signals. The six signals have made MATLAB identification simulation. Simulation results show that this method is feasible and has high recognition rate. Simulation results verify that such recognition methods maintain a high recognition rate under conditions with low signal-to-noise ratio. This identification method can be extended to more MASK (M-ary Amplitude Shift Keying), MPSK (M-ary Phase Shift Keying), MFSK (M-ary Frequency Shift Keying), MQAM (M-ary Quadrature Amplitude Modulation) signal identification.展开更多
An electromagnetically induced grating in a four-level tripod-type atomic system is studied theoretically. By virtue of a weak standing-wave signal field, the phase modulation effectively diffracts a weak probe field ...An electromagnetically induced grating in a four-level tripod-type atomic system is studied theoretically. By virtue of a weak standing-wave signal field, the phase modulation effectively diffracts a weak probe field into the first-order direction. By changing the weak signal field, the diffraction of the weak probe field can be modulated in real time, and a first-order diffraction efficiency of more than 32% can be obtained with proper parameters. Such a system has a potential application in an all-optical switch controlled by a weak optical signal.展开更多
This paper deals with modulation classification under the alpha-stable noise condition. Our goal is to discriminate orthogonal frequency division multiplexing (OFDM) modulation type from single carrier linear digital ...This paper deals with modulation classification under the alpha-stable noise condition. Our goal is to discriminate orthogonal frequency division multiplexing (OFDM) modulation type from single carrier linear digital (SCLD) modulations in this scenario. Based on the new results concerning the generalized cyclostationarity of these signals in alpha-stable noise which are presented in this paper, we construct new modulation classification features without any priori information of carrier frequency and timing offset of the received signals, and use support vector machine (SVM) as classifier to discriminate OFDM from SCLD. Simulation results show that the recognition accuracy of the proposed algorithm can be up to 95% when the mix signal to noise ratio (MSNR) is up to ?1 dB.展开更多
Modulational instability is an important area of research with important practical and theoretical significance in fluid mechanics,optics,plasma physics,and military and communication engineering.In this paper,using m...Modulational instability is an important area of research with important practical and theoretical significance in fluid mechanics,optics,plasma physics,and military and communication engineering.In this paper,using multiscale analysis and a perturbation expansion method,starting from the quasi-geostrophic potential vortex equation,a new(2+1)-dimensional highorder nonlinear Schrodinger equation describing Rossby waves in stratified fluids is obtained.Based on this equation,conditions for the occurrence of modulational instability of Rossby waves are analyzed.Moreover,the effects of factors such as the dimension and order of the equation and the latitude at which Rossby waves occur on modulational instability are discussed.It is found that the(2+1)-dimensional equation provides a good description of the modulational instability of Rossby waves on a plane.The high-order terms affect the modulational instability,and it is found that instability is more likely to occur at high latitudes.展开更多
This research investigates the digital-to-analog converter(DAC)free architecture for the digital reconfigurable intelligent surface(RIS)system,where the transmission lines are implemented for reflection coefficient(RC...This research investigates the digital-to-analog converter(DAC)free architecture for the digital reconfigurable intelligent surface(RIS)system,where the transmission lines are implemented for reflection coefficient(RC)control to reduce power consumption.In the proposed architecture,the radio frequency(RF)switch based phase shifter is considered.By using a single-pole four-throw(SP4T)switch to simultaneously control the RCs of a group of elements,a 2-bit phase shifter is realized for passive beam steering.A novel modulation scheme is developed to explore the cost effectiveness,which approaches the performance of traditional quadrature amplitude modulation(QAM).Specifically,to overcome the limitation of the phase shift bits,joint frequency-shift and phase-rotation operations are applied to the constellation points.The simulation and experimental results demonstrate that the proposed architecture is capable of providing an ideal transmission performance.Moreover,64-and 256-QAM modulation schemes could be implemented by expanding the elements and phase bits.展开更多
Background: The aim of this review is to summarize the optical quality results in patients following theimplantation of the V4c implantable collamer lens with a central port (ICL, STAAR Surgical Inc.).Main text: A lit...Background: The aim of this review is to summarize the optical quality results in patients following theimplantation of the V4c implantable collamer lens with a central port (ICL, STAAR Surgical Inc.).Main text: A literature search in several databases was carried out to identify those publications, both prospective,retrospective and/or comparative with other refractive surgery procedures, reporting optical outcomes of patientswho were implanted with the V4c ICL model. A total of 17 clinical studies published between 2012 and 2021 wereincluded in this review. A detailed analysis of the available data was performed including number of eyes, follow-upand preoperative spherical equivalent. Specifically, the review focused on several optical parameters includinghigher-order aberrations (HOAs), modulation transfer function (MTF) cut-off frequency and Strehl ratio. This reviewencompassed a total of 817 eyes measured using different optical devices based on Hartmann-Shack, retinal imagequality measurement and ray-tracing technologies at different follow-ups.Conclusions: The outcomes found in this review lead us to conclude that the ICL V4c model provides good opticalquality, by means of different metrics, when implanted.展开更多
Recently, there has been significant research interest in higher-order topological states within artificial lattices, primarily due to their potential for manipulating waves. In this study, we focus on a three-dimensi...Recently, there has been significant research interest in higher-order topological states within artificial lattices, primarily due to their potential for manipulating waves. In this study, we focus on a three-dimensional hexagonal bilayer acoustic crystal with rotation, layer, and translation degrees of freedom. By systematically reducing the crystal symmetries, we realize a full hierarchical structure of the higher-order topological states. This hierarchical progression begins with the valley-induced twodimensional surface state, followed by the one-dimensional hinge state that arises from the topological obstruction, and ultimately culminating in the zero-dimensional corner state resulting from the edge polarization mechanism. Through finite element simulations and numerical calculations of topological invariants, we confirm the topological origins of all these hierarchical states. Moreover, we successfully verified the full hierarchical topology by directly probing the acoustic field within a finitesized three-dimensional sample. This study offers novel perspectives on the fundamental research pertaining to wave modulation and the intelligent control of sound fields.展开更多
In this paper, we proposed a novel modulation format identification method for square M-quadrature amplitude modulation (M-QAM) signals which is based on amplitude histogram space of the incoming data after analog-to-...In this paper, we proposed a novel modulation format identification method for square M-quadrature amplitude modulation (M-QAM) signals which is based on amplitude histogram space of the incoming data after analog-to-digital conversion, chromatic dispersion com-pensation at the receiver. We demonstrated the identifica-tion of quadrature phase-shift keying (QPSK), 16-QAM, 64-QAM formats with an amplitude histogram space. Simulation results show that it achieve 100% identification accuracy when the incoming signal OSNR is 14 dB to identify the modulation format of QPSK, 16-QAM, and 64-QAM signals in digital coherent systems. The method has low complexity and small delay.展开更多
文摘A new feature based on higher order statistics is proposed for classification of MPSKsignals, which is invariant with respect to translation (shift), scale and rotation transforms of MPSK signal constellations, and can suppress additive color or white Gaussian noise. Application of the new feature to classification of MPSK signals, at medium signal-to-noise ratio with specified sample size, results in high probability of correct identification. Finally, computer simulations and comparisons with existing algorithms are given.
基金supported by the National Natural Science Foundation of China(6127125061571460)
文摘A hybrid carrier（HC） scheme based on weighted-type fractional Fourier transform（WFRFT） has been proposed recently.While most of the works focus on HC scheme＇s inherent characteristics, little attention is paid to the WFRFT modulation recognition.In this paper, a new theory is provided to recognize the WFRFT modulation based on higher order cumulants（HOC）. First, it is deduced that the optimal WFRFT received order can be obtained through the minimization of 4 th-order cumulants, C_（42）. Then, a combinatorial searching algorithm is designed to minimize C_（42）.Finally, simulation results show that the designed scheme has a high recognition rate and the combinatorial searching algorithm is effective and reliable.
文摘Background:The aim of this review is to summarize the optical quality results in patients following the implantation of the V4c implantable collamer lens with a central port(ICL,STAAR Surgical Inc.).Main text:A literature search in several databases was carried out to identify those publications,both prospective,retrospective and/or comparative with other refractive surgery procedures,reporting optical outcomes of patients who were implanted with the V4c ICL model.A total of 17 clinical studies published between 2012 and 2021 were included in this review.A detailed analysis of the available data was performed including number of eyes,follow-up and preoperative spherical equivalent.Specifically,the review focused on several optical parameters including higher-order aberrations(HOAs),modulation transfer function(MTF)cut-off frequency and Strehl ratio.This review encompassed a total of 817 eyes measured using different optical devices based on Hartmann-Shack,retinal image quality measurement and ray-tracing technologies at different follow-ups.Conclusions:The outcomes found in this review lead us to conclude that the ICL V4c model provides good optical quality,by means of different metrics,when implanted.
基金supported by the National Natural Science Foundation of China(Nos.62225503,61835005,and 62205151)。
文摘We propose a neural network equalization delta-sigma modulation(DSM)technique.After performing DSM on the multiorder quadrature amplitude modulation(QAM)orthogonal frequency division multiplexing(OFDM)signal at the transmitting end,neural network equalizer technology is used in the digital signal processing at receiving end.Applying this technology to a 4.6 km W-band millimeter wave system,it is possible to achieve a 1 Gbaud 8192-QAM OFDM signal transmission.The data rate reached 23.4 Gbit/s with the bit error rate at 3.8×10^(-2),lower than soft-decision forward-error correction threshold(4×10^(-2)).
基金supported by the Foundation of Chinese People’s Liberation Army General Equipment Department(41101020303)
文摘This paper presents a joint high order statistics （HOS） and signal-to-noise ratio （SNR） algorithm for the recognition of multiple-input multiple-output （MIMO） radar signal without a priori knowledge of the signal parameters. This method is capable of recognizing the MIMO radar signal as well as discriminating it from single-carrier signal adopted by conventional radar. Meanwhile, the sub-carrier number of the none-coding MIMO radar signal is estimated. Extensive simulations are carried out in different operating conditions. Simulation results prove the feasibility and indicate that the recognition probability could reach over 90% when the value of SNR is above 0 dB.
基金Project supported by the Fundamental Application Research Project of the Department of Science ＆ Technology of Sichuan Province （Grant Nos 05JY029-084 and 04JY029-103）, the Key Program of Natural Science Foundation of Educational Commission of Sichuan Province （Grant No 2006A124）, and the Foundation of Science ＆ Technology Development of Chengdu University of Information Technology （Grant No KYTZ20060604）.
文摘This paper investigates the effects of walk-off among optical pulses on cross-phase modulation induced modulation instability in the normal dispersion region of an optical fibre with high-order dispersion. The results indicate that, in the case of high-order dispersion, the walk-off effect takes on new characteristics and will influence considerably the shape, position and especially the number of the spectral regions of the gain spectra of modulation instability. Not only the group-velocity mismatch, but also the difference of the third-order dispersion of two optical waves will alter the gain spectra of modulation instability but in different ways. Depending on the values of the walk-off parameters, the number of the spectral regions may increase from two to at most four, and the spectral shape and position may change too.
基金supported by the National Natural Science Foundation of China(Grants Nos.11004126 and 61275212)the Natural Science Foundation of Shanxi Province,China(Grant No.2011021003-1)
文摘The electromagnetically induced grating effect in thermal and cold atoms has been studied theoretically. Studies have shown that, by adjusting the parameters, the first-order diffraction efficiency of the probe beam in the cold atomic system and the thermal atomic system is 34% and 31%, respectively, which is very close to the ideal diffraction efficiency of the sinusoidal grating. However, it is more difficult to prepare the cold atomic system than to prepare the thermal atomic system in the practical application, so the study of the electromagnetically induced grating effect in the thermal atomic system may be helpful for practical applications.
基金supported in part by the Jiangsu Natural Science Foundation of China under Grant BK20180013in part by the Shenzhen Science and Technology Innovation Committee(STIC)under Grant JCYJ20180306174439784.
文摘The pulse-width-modulated(PWM)current-source converters(CSCs)fed electric machine systems can be considered as a type of high reliability energy conversion systems,since they work with the long-life DC-link inductor and offer high fault-tolerant capability for short-circuit faults.Besides,they provide motor friendly waveforms and four-quadrant operation ability.Therefore,they are suitable for high-power applications of fans,pumps,compressors and wind power generation.The purpose of this paper is to comprehensively review recent developments of key technologies on modulation and control of high-power(HP)PWM-CSC fed electric machines systems,including reduction of low-order current harmonics,suppression of inductor–capacitor(LC)resonance,mitigation of common-mode voltage(CMV)and control of modular PWM-CSC fed systems.In particular,recent work on the overlapping effects during commutation,LC resonance suppression under fault-tolerant operation and collaboration of modular PMW-CSCs are described.Both theoretical analysis and some results in simulations and experiments are presented.Finally,a brief discussion regarding the future trend of the HP CSC fed electric machines systems is presented.
文摘This paper mainly studies the data characteristics of high order cumulants using digitally modulated signals, and constructs the identification feature parameters that can distinguish the signal modulation type by the high-order cumulants data of the digital modulation signal. Set the identification signal modulation type determination threshold based on the value of the identification feature parameter. The identification feature parameter value of the signal modulation type is compared with the set determination threshold, to realize the recognition of digital modulation signal. This identification method is implemented based on MATLAB design, with a 2ASK (2-ary Amplitude Shift Keying) signal, 4ASK (4-ary Amplitude Shift Keying) signal, 2PSK (2-ary Phase Shift Keying) signal, 4PSK (4-ary Phase Shift Keying) signal, 2FSK (2-ary Frequency Shift Keying) signal, 4FSK (4-ary Frequency Shift Keying) signal. The second, fourth and sixth order cumulants of the six signals were analyzed. Calculate the selected identification feature parameter value and the determination threshold to identify the six signals. The six signals have made MATLAB identification simulation. Simulation results show that this method is feasible and has high recognition rate. Simulation results verify that such recognition methods maintain a high recognition rate under conditions with low signal-to-noise ratio. This identification method can be extended to more MASK (M-ary Amplitude Shift Keying), MPSK (M-ary Phase Shift Keying), MFSK (M-ary Frequency Shift Keying), MQAM (M-ary Quadrature Amplitude Modulation) signal identification.
基金supported by the National Natural Science Foundation of China(Grants Nos.11004126 and 61275212)the Natural Science Foundation of ShanxiProvince,China(Grant No.2011021003-1)the National Basic Research Program of China(Grant No.2010CB923102)
文摘An electromagnetically induced grating in a four-level tripod-type atomic system is studied theoretically. By virtue of a weak standing-wave signal field, the phase modulation effectively diffracts a weak probe field into the first-order direction. By changing the weak signal field, the diffraction of the weak probe field can be modulated in real time, and a first-order diffraction efficiency of more than 32% can be obtained with proper parameters. Such a system has a potential application in an all-optical switch controlled by a weak optical signal.
文摘This paper deals with modulation classification under the alpha-stable noise condition. Our goal is to discriminate orthogonal frequency division multiplexing (OFDM) modulation type from single carrier linear digital (SCLD) modulations in this scenario. Based on the new results concerning the generalized cyclostationarity of these signals in alpha-stable noise which are presented in this paper, we construct new modulation classification features without any priori information of carrier frequency and timing offset of the received signals, and use support vector machine (SVM) as classifier to discriminate OFDM from SCLD. Simulation results show that the recognition accuracy of the proposed algorithm can be up to 95% when the mix signal to noise ratio (MSNR) is up to ?1 dB.
基金supported by the National Natural Science Foundation of China(No.11975143)。
文摘Modulational instability is an important area of research with important practical and theoretical significance in fluid mechanics,optics,plasma physics,and military and communication engineering.In this paper,using multiscale analysis and a perturbation expansion method,starting from the quasi-geostrophic potential vortex equation,a new(2+1)-dimensional highorder nonlinear Schrodinger equation describing Rossby waves in stratified fluids is obtained.Based on this equation,conditions for the occurrence of modulational instability of Rossby waves are analyzed.Moreover,the effects of factors such as the dimension and order of the equation and the latitude at which Rossby waves occur on modulational instability are discussed.It is found that the(2+1)-dimensional equation provides a good description of the modulational instability of Rossby waves on a plane.The high-order terms affect the modulational instability,and it is found that instability is more likely to occur at high latitudes.
基金Project supported by the National Key R&D Program of China(No.2019YFB1803400)。
文摘This research investigates the digital-to-analog converter(DAC)free architecture for the digital reconfigurable intelligent surface(RIS)system,where the transmission lines are implemented for reflection coefficient(RC)control to reduce power consumption.In the proposed architecture,the radio frequency(RF)switch based phase shifter is considered.By using a single-pole four-throw(SP4T)switch to simultaneously control the RCs of a group of elements,a 2-bit phase shifter is realized for passive beam steering.A novel modulation scheme is developed to explore the cost effectiveness,which approaches the performance of traditional quadrature amplitude modulation(QAM).Specifically,to overcome the limitation of the phase shift bits,joint frequency-shift and phase-rotation operations are applied to the constellation points.The simulation and experimental results demonstrate that the proposed architecture is capable of providing an ideal transmission performance.Moreover,64-and 256-QAM modulation schemes could be implemented by expanding the elements and phase bits.
文摘Background: The aim of this review is to summarize the optical quality results in patients following theimplantation of the V4c implantable collamer lens with a central port (ICL, STAAR Surgical Inc.).Main text: A literature search in several databases was carried out to identify those publications, both prospective,retrospective and/or comparative with other refractive surgery procedures, reporting optical outcomes of patientswho were implanted with the V4c ICL model. A total of 17 clinical studies published between 2012 and 2021 wereincluded in this review. A detailed analysis of the available data was performed including number of eyes, follow-upand preoperative spherical equivalent. Specifically, the review focused on several optical parameters includinghigher-order aberrations (HOAs), modulation transfer function (MTF) cut-off frequency and Strehl ratio. This reviewencompassed a total of 817 eyes measured using different optical devices based on Hartmann-Shack, retinal imagequality measurement and ray-tracing technologies at different follow-ups.Conclusions: The outcomes found in this review lead us to conclude that the ICL V4c model provides good opticalquality, by means of different metrics, when implanted.
基金supported by the Key-Area Research and Development Program of Guangdong Province(Grant No.2020B010190002)the National Natural Science Foundation of China(Grant No.12104480)the IACAS Frontier Exploration Project(Grant No.QYTS202110)。
文摘Recently, there has been significant research interest in higher-order topological states within artificial lattices, primarily due to their potential for manipulating waves. In this study, we focus on a three-dimensional hexagonal bilayer acoustic crystal with rotation, layer, and translation degrees of freedom. By systematically reducing the crystal symmetries, we realize a full hierarchical structure of the higher-order topological states. This hierarchical progression begins with the valley-induced twodimensional surface state, followed by the one-dimensional hinge state that arises from the topological obstruction, and ultimately culminating in the zero-dimensional corner state resulting from the edge polarization mechanism. Through finite element simulations and numerical calculations of topological invariants, we confirm the topological origins of all these hierarchical states. Moreover, we successfully verified the full hierarchical topology by directly probing the acoustic field within a finitesized three-dimensional sample. This study offers novel perspectives on the fundamental research pertaining to wave modulation and the intelligent control of sound fields.
基金the National Natural Science Foundation of China (Grant Nos. 61575071, and 61331010).
文摘In this paper, we proposed a novel modulation format identification method for square M-quadrature amplitude modulation (M-QAM) signals which is based on amplitude histogram space of the incoming data after analog-to-digital conversion, chromatic dispersion com-pensation at the receiver. We demonstrated the identifica-tion of quadrature phase-shift keying (QPSK), 16-QAM, 64-QAM formats with an amplitude histogram space. Simulation results show that it achieve 100% identification accuracy when the incoming signal OSNR is 14 dB to identify the modulation format of QPSK, 16-QAM, and 64-QAM signals in digital coherent systems. The method has low complexity and small delay.
