Background: Studies have pointed out the influence of different children’s activities and prolonged use of digital products on their social development. However, whether the parent-child activities and using digital ...Background: Studies have pointed out the influence of different children’s activities and prolonged use of digital products on their social development. However, whether the parent-child activities and using digital devices were serial mediators of the relationship between children’s health and social development needs further verification. Purpose: This study explored how parent-child activities and children’s use of digital devices influence the relationship between children’s health and their social competence. Method: This study used data from Kids in Taiwan: National Longitudinal Study of Child Development and Care. A total sample of 2164 participants was used in this study. Serial mediation analyses were performed using model six of Hayes’ PROCESS (2012). Results: This study found that parent-child activities and the use of digital devices can serially mediate the relationship between children’s health and social competence. Children’s health could directly improve their social competence, but it could also serially mediate social competence by increasing parent-child activities and reducing the use of digital devices. Conclusion: Childcare policy planners and parenting educators should not only call on parents to reduce the use of electronic products for their children, but also encourage parents to spend more time interacting with their children, so that children can learn social skills by interacting with others in their daily lives.展开更多
Two methods of calculating the parameters and characterizing the degree of pulse electrical disturbances influence on digital devices functioning, both analytical and numerical, are considered here. The analytical met...Two methods of calculating the parameters and characterizing the degree of pulse electrical disturbances influence on digital devices functioning, both analytical and numerical, are considered here. The analytical method permits one to assess the error occurrence probability in transmitting the data packets considering the dependence on the signal pulses energies-to-pulse disturbances energies ratio and the disturbances repetition frequency-to-data transmission rate ratio and also the dependence on the bits quantity in the packet. The numerical method allows one to assess the specific effect of the repetitive pulse disturbance influence on the digital devices functioning （the number of errors in transmitted data packets, transmission rate, etc.） depending on such factors as the repetition frequency, the disturbance waveform and duration, the mode of data coding, etc..展开更多
Digital devices have reshaped human communication in today's technology driven society. These devices, as a medium of identity and self-expression, now determine personal, domestic, and corporate interactions by p...Digital devices have reshaped human communication in today's technology driven society. These devices, as a medium of identity and self-expression, now determine personal, domestic, and corporate interactions by providing access to digital and online facilities enabled by an influx of computer and portable mobile devices into the Nigerian market. The effect of this digitalization on self-expression cuts across contexts and age categories. This study, driven by new media theory and the theory of transitivity in systemic functional linguistics, examined the influence of digital devices on identity and self-expression among undergraduate teenagers in Osogbo, Osun State. Carefully selected through stratified and convenience sampling techniques, undergraduate teenagers involved in the survey—which employed a questionnaire—and focus group discussions, revealed that their preference for interactive chats, social media picture galleries, captions on photographs, and video subtitles outweighed their propensity to read long or academic texts and partake in online economic activities. Most of our respondents explored online communication through their mobile devices, while others accessed the internet on personal computers at home with little or no parental guidance or supervision. Subsequently, age falsification, wrong or misleading self-identification, and a consequent cultural literacy were common among undergraduate teenagers online. A selfregulation facility was then recommended alongside parental and caregiver monitoring of teenagers' virtual communication to reduce the influence of social media on teenagers' time management and self-identity. Further research is also recommended in the field of ICT to detect age falsification and other forms of online false-identity among minors.展开更多
The habitual use of smartphones during meals has become a common behavior,raising concerns about its potential impact on eating habits and metabolic health.The present narrative review investigates how using a smartph...The habitual use of smartphones during meals has become a common behavior,raising concerns about its potential impact on eating habits and metabolic health.The present narrative review investigates how using a smartphone or tablet during meals can cause distractions and negatively affect metabolic health.A comprehensive narrative review was conducted by synthesizing peer-reviewed studies on the interplay between smartphone use during meals,eating behaviors,and metabolic health.Relevant literature was identified through searches in electronic databases and organized thematically to highlight trends and research gaps.By synthesizing evidence from existing literature,this review highlights that smartphone use during meals is associated with increased caloric intake,altered food composition,and disruptions in postprandial metabolic responses.These effects are mediated by reduced meal awareness and psychological distractions,including multitasking.Variability in findings arises from differences in study designs and populations.This review identifies critical research gaps,including the lack of longitudinal studies and the need to explore mechanisms underlying these relationships.By summarizing trends and patterns,this narrative review offers valuable insights into the complex interplay between digital device use,eating habits,and metabolic health,providing a foundation for future research and interventions.展开更多
AIM:To characterize the ocular surface characteristics in the Nepalese population across all age groups who have used digital screens for extended durations over several years.METHODS:In a cross-sectional,observationa...AIM:To characterize the ocular surface characteristics in the Nepalese population across all age groups who have used digital screens for extended durations over several years.METHODS:In a cross-sectional,observational study,144 digital screen users were assessed for dry eye disease(DED)using subjective and objective measures.The Ocular Surface Disease Index(OSDI)Questionnaire evaluated symptoms,followed by clinical assessments,including slit lamp biomicroscopy,tear breakup time(TBUT),Oxford Scheme grading,and Schirmer I test.DED was diagnosed if a patient had an OSDI score over 13 and at least two clinical signs(OSDI,Schirmer I test,or ocular staining).The prevalence of DED was calculated based on the proportion of patients meeting these criteria.RESULTS:Of the 144 participants(mean age:34.6±15.2y),78(54.2%)were female.The use of digital screens varied between 2-8h(mean duration:4.1±2.7h)per day.The mean OSDI score,TBUT score,and the Schirmer I scores were 22.7±10.5(max-min:24.4-20.9),6.8±4.2s(max-min:7.5-6.1),and 12.3±4.6 mm(max-min:13.1-11.5)respectively with 95%confidence interval(β=1.96),and a two-tailed statistical significance level of 5%(α=0.05).With increased screen use,TBUT shortened and OSDI scores increased significantly(P<0.01),though Schirmer I scores were unaffected(P>0.05).The prevalence of DED ranged from 6.3%to 22.9%in those using screens for more than 2h,with an overall prevalence of 67.4%among digital screen users.CONCLUSION:There is a significant association between prolonged use of digital screens and clinical markers of dry eye signs and symptoms.展开更多
Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by usin...Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by using the digital grayscale modulation method. The infrared image modulation model of a digital micro-mirror device （DMD） is established and then the infrared scene simulator prototype which is based on DMD grayscale modulation is developed. To evaluate its main parameters such as resolution, contrast, minimum temperature difference, gray scale, various DMD subsystems such as signal decoding, image normalization, synchronization drive, pulse width modulation （PWM） and DMD chips are designed. The infrared scene simulator is tested on a certain infrared missile seeker. The test results show preliminarily that the infrared scene simulator has high gray scale, small geometrical distortion and highly resolvable imaging resolution and contrast and yields high-fidelity images, thus being able to meet the requirements for the infrared scene simulation inside a laboratory.展开更多
Structured illumination microscopy(SIM)is a promising super-resolution technique for imaging subcellular structures and dynamics due to its compatibility with most commonly usedffuorescent labeling methods.Structured ...Structured illumination microscopy(SIM)is a promising super-resolution technique for imaging subcellular structures and dynamics due to its compatibility with most commonly usedffuorescent labeling methods.Structured illumination can be obtained by either laser interference or projection of fringe patterns.Here,we proposed a fringe projector composed of a compact multiwavelength LEDs module and a digital micromirror device(DMD)which can be directly attached to most commercial invertedffuorescent microscopes and update it into a SIM system.The effects of the period and duty cycle of fringe patterns on the modulation depth of the structured lightfield were studied.With the optimized fringe pattern,1:6×resolution improvement could be obtained with high-end oil objectives.Multicolor imaging and dynamics of subcellular organelles in live cells were also demonstrated.Our method provides a low-cost solution for SIM setup to expand its wide range of applications to most research labs in thefield of life science and medicine.展开更多
We present a digital micromirror device（DMD） based superpixel method for focusing light through scattering media by modulating the complex field of incident light. Firstly, we numerically and experimentally investig...We present a digital micromirror device（DMD） based superpixel method for focusing light through scattering media by modulating the complex field of incident light. Firstly, we numerically and experimentally investigate focusing light through a scattering sample using the superpixel methods with different target complex fields.Then, single-point and multiple-point focusing experiments are performed using this superpixel-based complex modulation method. In our experiment, up to 71.5% relative enhancement is realized. The use of the DMDbased superpixel method for the control of the complex field of incident light opens an avenue to improve the enhancement of focusing light through scattering media.展开更多
An ultrafast spectrum programmable femtosecond laser may enhance the performance of a wide variety of scientific applications,e.g.,multi-photon imaging.In this paper,we report a digital micromirror device(DMD)-based u...An ultrafast spectrum programmable femtosecond laser may enhance the performance of a wide variety of scientific applications,e.g.,multi-photon imaging.In this paper,we report a digital micromirror device(DMD)-based ultrafast pulse shaper,i.e.,DUPS,for femtosecond laser arbitrary amplitude shaping-the first time a programmable binary device reported to shape the amplitudes of ultrafast pulses spectrum at up to 32 kHz rate over a broad wavelength range.The DUPS is highly effcient,compact,and low cost based on the use of a DMD in combination with a transmission grating.Spatial and temporal dispersion introduced by the DUPS is compensated by a quasi-4-f setup and a grating pair,respectively.Femtosecond pulses with arbitrary spectrum shapes,including rectangular,sawtooth,triangular,double-pulse,and exponential profile,have been demonstrated in our experiments.A feedback operation process is implemented in the DUPS to ensure a robust and repeatable shaping process.The total effciency of the DUPS for amplitude shaping is measured to be 27%.展开更多
A new method which employs compressive sensing(CS) to reconstruct the sparse spectrum is designed and experimentally demonstrated. On the basis of CS theory, the simulation results indicate that the probability of rec...A new method which employs compressive sensing(CS) to reconstruct the sparse spectrum is designed and experimentally demonstrated. On the basis of CS theory, the simulation results indicate that the probability of reconstruction is high when the step of the sparsity adaptive matching pursuit algorithm is confirmed as 1. Contrastive analysis for four kinds of commonly used measurement matrices: part Hadamard, Bernoulli, Toeplitz and Circular matrix, has been conducted. The results illustrate that the part Hadamard matrix has better performance of reconstruction than the other matrices. The experimental system of the spectral compression reconstruction is mainly based on the digital micro-mirror device(DMD). The experimental results prove that CS can reconstruct sparse spectrum well under the condition of 50% sampling rate. The system error 0.0781 is obtained, which is defined by the average value of the 2-norm. Furthermore, the proposed method shows a dominant ability to discard redundancy.展开更多
All-optical analog-to-digital conversion (ADC) has been extensively researched to break through the inherently limited operating speed of electronic devices. In this paper, we use the photonic crystal fiber (PCF) for ...All-optical analog-to-digital conversion (ADC) has been extensively researched to break through the inherently limited operating speed of electronic devices. In this paper, we use the photonic crystal fiber (PCF) for time-stretch (TS) analog-to-digital (A/D) conversion system through generating low noise, linear chirp distribution and flat super-continuum (SC). Based on the radio frequency (RF) analog signal modulated to the linearly chirped super-continuum, the large-dispersion photonic crystal fiber is used for time-domain stretching.展开更多
Research is currently ongoing to investigate the use of assistive technology by people with mild dementia to support independent living at home. The aim of this study was to describe professional caregivers’ percepti...Research is currently ongoing to investigate the use of assistive technology by people with mild dementia to support independent living at home. The aim of this study was to describe professional caregivers’ perceptions on the prerequisites for and consequences of people with mild dementia using a digital photo diary to facilitate their talks about daily events with their family members. A questionnaire was sent out to 582 participants (response rate 70.1%) to elucidate the professional caregivers’ perceptions on the use of the digital photo diary. The questionnaire contained both quantitative and qualitative data and was analyzed with descriptive statistics, factor analysis, multivariate analysis of covariance and qualitative content analysis. This study reports the results related to prerequisites and consequences of using the photo diary. The results from the factor analysis revealed four factors: Trust, Vulnerability, Dependency/Independency and Control. The qualitative content analysis resulted in five categories: Immediate implementation after receiving a diagnose is required, Relatives’ participation is a necessity, Strengthened self-esteem and meaningful everyday life, Increased alienation and a feeling of isolation and Assistive digital devices provide opportunities. The theme was interpreted as: Personalization and the preservation of dignity. The conclusion that can be drawn from this study is that the participants had an overall positive view of the usage of this specific digital photo diary for people suffering from dementia, but rigorous considerations needs before implementation of the device and regularly follow ups if dignity is to be maintained for people with dementia.展开更多
Digital holography has high potentials for future 3D imaging and display technology.We present a method for a dynamic full-color digital holographic 3D display on single digital micro-mirror device(DMD)with full-color...Digital holography has high potentials for future 3D imaging and display technology.We present a method for a dynamic full-color digital holographic 3D display on single digital micro-mirror device(DMD)with full-color,high-speed and high-fidelity characteristics.We combine the square regions of adjacent micro-mirrors into super-pixels that can modulate amplitude and phase independently.Gray images are achieved by amplitude modulation and precise positioning of each color is achieved by phase modulation.The proposed method realizes a full-color imaging based on the three primary colors and achieves measured structural similarity of more than 88%and color similarity of more than 98%,while retaining the high switch speed of 9 kHz,thus achieving dynamic full-color 3D display on charge-coupled device(CCD).展开更多
For the performance issues of satellite transceivers suffering passive intermodulation interference,a novel and effective digital suppression algorithm is presented in this paper.In contrast to analog approaches,digit...For the performance issues of satellite transceivers suffering passive intermodulation interference,a novel and effective digital suppression algorithm is presented in this paper.In contrast to analog approaches,digital passive intermodulation（PIM） suppression approaches can be easily reconfigured and therefore are highly attractive for future satellite communication systems.A simplified model of nonlinear distortion from passive microwave devices is established in consideration of the memory effect.The multiple high-order PIM products falling into the receiving band can be described as a bilinear predictor function.A suppression algorithm based on a bilinear polynomial decorrelated adaptive filter is proposed for baseband digital signal processing.In consideration of the time-varying characteristics of passive intermodulation,this algorithm can achieve the rapidness of online interference estimation and low complexity with less consumption of resources.Numerical simulation results show that the algorithm can effectively compensate the passive intermodulation interference,and achieve a high signal-to-interference ratio gain.展开更多
As we all know,eyes are the windows of our souls.They make us see the colorful world and understand others’feelings.However,by①the wide use of digital devices like smartphones and computers,many of us are facing eye...As we all know,eyes are the windows of our souls.They make us see the colorful world and understand others’feelings.However,by①the wide use of digital devices like smartphones and computers,many of us are facing eye problems.So,it's important to protect our eyes。展开更多
Based on the helix rotating screen and the digital micro-mirror device （DMD）, the former proto of volumetric-swept display system is improved. The 3-D display system adopting a helix rotating screen to construct an ...Based on the helix rotating screen and the digital micro-mirror device （DMD）, the former proto of volumetric-swept display system is improved. The 3-D display system adopting a helix rotating screen to construct an imaging space meliorate the defects, such as the smaller image space, the fewer voxels and the severer voxel overlap dead zone caused by planar rotating screen. DMD with spatial light modular （SLM） technology increases the transmission bandwidth of 3-D data in the voxel activation subsystem and activate multi-voxel once time. The volumetric-swept system based on helix rotating screen and DMD is developed. The experimental results show that the image space, the vision dead zone, the voxels on slice, and the voxel activation capacity of the designed proto are superior to the plane rotating screen system.展开更多
A high-efficiency inverse design of"digital"subwavelength nanophotonic devices using the adjoint method is proposed.We design a single-mode 3dB power divider and a dual-mode demultiplexer to demonstrate the ...A high-efficiency inverse design of"digital"subwavelength nanophotonic devices using the adjoint method is proposed.We design a single-mode 3dB power divider and a dual-mode demultiplexer to demonstrate the efficiency of the proposed inverse design approach,called the digitized adjoint method,for single-and dual-object optimization,respectively.The optimization comprises three stages:1)continuous variation for an"analog"pattern;2)forced permittivity biasing for a"quasi-digital"pattern;and 3)a multilevel digital pattern.Compared with the conventional brute-force method,the proposed method can improve design efficiency by about five times,and the performance optimization can reach approximately the same level.The method takes advantages of adjoint sensitivity analysis and digital subwavelength structure and creates a new way for the efficient and high-performance design of compact digital subwavelength nanophotonic devices,which could overcome the efficiency bottleneck of the brute-force method,which is restricted by the number of pixels of a digital pattern,and improve the device performance by extending a conventional binary pattern to a multilevel one.展开更多
Conventional semi-active laser guidance takes advantage of the laser designator to illuminate the stable and uniform laser spot on target precisely.The seeker collects the reflected light by a quadrant detector and ou...Conventional semi-active laser guidance takes advantage of the laser designator to illuminate the stable and uniform laser spot on target precisely.The seeker collects the reflected light by a quadrant detector and outputs the relative position information to guide the missile to the illuminating laser spot.However,the designation and guidance accuracy could be jeopardized by the randomly drifting of laser spot caused by the instability of designation platform and air turbulence.In this work,ghost imaging technique is adapted to a quadrant detector semi-active seeker by utilizing structured illumination on the target.With a series of structured illumination masks,the signals from the quadrant detector are multiplexed to perform calculation of the target relative position as well as image reconstruction of the illuminated area simultaneously.Automatic target recognition methods could be further applied to the reconstructed image to calculate the designating error and correct the guidance.The results of simulation and experiment demonstrate that the proposed method could improve the guidance accuracy in many circumstances which would lead to attacking deviation if conventional semi-active laser guidance is used.展开更多
Structured illumination microscopy(SIM)achieves super-resolution(SR)by modulating the high-frequency information of the sample into the passband of the optical system and subsequent image reconstruction.The traditiona...Structured illumination microscopy(SIM)achieves super-resolution(SR)by modulating the high-frequency information of the sample into the passband of the optical system and subsequent image reconstruction.The traditional Wiener-filtering-based reconstruction algorithm operates in the Fourier domain,it requires prior knowledge of the sinusoidal illumination patterns which makes the time-consuming procedure of parameter estimation to raw datasets necessary,besides,the parameter estimation is sensitive to noise or aberration-induced pattern distortion which leads to reconstruction artifacts.Here,we propose a spatial-domain image reconstruction method that does not require parameter estimation but calculates patterns from raw datasets,and a reconstructed image can be obtained just by calculating the spatial covariance of differential calculated patterns and differential filtered datasets(the notch filtering operation is performed to the raw datasets for attenuating and compensating the optical transfer function(OTF)).Experiments on reconstructing raw datasets including nonbiological,biological,and simulated samples demonstrate that our method has SR capability,high reconstruction speed,and high robustness to aberration and noise.展开更多
文摘Background: Studies have pointed out the influence of different children’s activities and prolonged use of digital products on their social development. However, whether the parent-child activities and using digital devices were serial mediators of the relationship between children’s health and social development needs further verification. Purpose: This study explored how parent-child activities and children’s use of digital devices influence the relationship between children’s health and their social competence. Method: This study used data from Kids in Taiwan: National Longitudinal Study of Child Development and Care. A total sample of 2164 participants was used in this study. Serial mediation analyses were performed using model six of Hayes’ PROCESS (2012). Results: This study found that parent-child activities and the use of digital devices can serially mediate the relationship between children’s health and social competence. Children’s health could directly improve their social competence, but it could also serially mediate social competence by increasing parent-child activities and reducing the use of digital devices. Conclusion: Childcare policy planners and parenting educators should not only call on parents to reduce the use of electronic products for their children, but also encourage parents to spend more time interacting with their children, so that children can learn social skills by interacting with others in their daily lives.
文摘Two methods of calculating the parameters and characterizing the degree of pulse electrical disturbances influence on digital devices functioning, both analytical and numerical, are considered here. The analytical method permits one to assess the error occurrence probability in transmitting the data packets considering the dependence on the signal pulses energies-to-pulse disturbances energies ratio and the disturbances repetition frequency-to-data transmission rate ratio and also the dependence on the bits quantity in the packet. The numerical method allows one to assess the specific effect of the repetitive pulse disturbance influence on the digital devices functioning （the number of errors in transmitted data packets, transmission rate, etc.） depending on such factors as the repetition frequency, the disturbance waveform and duration, the mode of data coding, etc..
文摘Digital devices have reshaped human communication in today's technology driven society. These devices, as a medium of identity and self-expression, now determine personal, domestic, and corporate interactions by providing access to digital and online facilities enabled by an influx of computer and portable mobile devices into the Nigerian market. The effect of this digitalization on self-expression cuts across contexts and age categories. This study, driven by new media theory and the theory of transitivity in systemic functional linguistics, examined the influence of digital devices on identity and self-expression among undergraduate teenagers in Osogbo, Osun State. Carefully selected through stratified and convenience sampling techniques, undergraduate teenagers involved in the survey—which employed a questionnaire—and focus group discussions, revealed that their preference for interactive chats, social media picture galleries, captions on photographs, and video subtitles outweighed their propensity to read long or academic texts and partake in online economic activities. Most of our respondents explored online communication through their mobile devices, while others accessed the internet on personal computers at home with little or no parental guidance or supervision. Subsequently, age falsification, wrong or misleading self-identification, and a consequent cultural literacy were common among undergraduate teenagers online. A selfregulation facility was then recommended alongside parental and caregiver monitoring of teenagers' virtual communication to reduce the influence of social media on teenagers' time management and self-identity. Further research is also recommended in the field of ICT to detect age falsification and other forms of online false-identity among minors.
文摘The habitual use of smartphones during meals has become a common behavior,raising concerns about its potential impact on eating habits and metabolic health.The present narrative review investigates how using a smartphone or tablet during meals can cause distractions and negatively affect metabolic health.A comprehensive narrative review was conducted by synthesizing peer-reviewed studies on the interplay between smartphone use during meals,eating behaviors,and metabolic health.Relevant literature was identified through searches in electronic databases and organized thematically to highlight trends and research gaps.By synthesizing evidence from existing literature,this review highlights that smartphone use during meals is associated with increased caloric intake,altered food composition,and disruptions in postprandial metabolic responses.These effects are mediated by reduced meal awareness and psychological distractions,including multitasking.Variability in findings arises from differences in study designs and populations.This review identifies critical research gaps,including the lack of longitudinal studies and the need to explore mechanisms underlying these relationships.By summarizing trends and patterns,this narrative review offers valuable insights into the complex interplay between digital device use,eating habits,and metabolic health,providing a foundation for future research and interventions.
文摘AIM:To characterize the ocular surface characteristics in the Nepalese population across all age groups who have used digital screens for extended durations over several years.METHODS:In a cross-sectional,observational study,144 digital screen users were assessed for dry eye disease(DED)using subjective and objective measures.The Ocular Surface Disease Index(OSDI)Questionnaire evaluated symptoms,followed by clinical assessments,including slit lamp biomicroscopy,tear breakup time(TBUT),Oxford Scheme grading,and Schirmer I test.DED was diagnosed if a patient had an OSDI score over 13 and at least two clinical signs(OSDI,Schirmer I test,or ocular staining).The prevalence of DED was calculated based on the proportion of patients meeting these criteria.RESULTS:Of the 144 participants(mean age:34.6±15.2y),78(54.2%)were female.The use of digital screens varied between 2-8h(mean duration:4.1±2.7h)per day.The mean OSDI score,TBUT score,and the Schirmer I scores were 22.7±10.5(max-min:24.4-20.9),6.8±4.2s(max-min:7.5-6.1),and 12.3±4.6 mm(max-min:13.1-11.5)respectively with 95%confidence interval(β=1.96),and a two-tailed statistical significance level of 5%(α=0.05).With increased screen use,TBUT shortened and OSDI scores increased significantly(P<0.01),though Schirmer I scores were unaffected(P>0.05).The prevalence of DED ranged from 6.3%to 22.9%in those using screens for more than 2h,with an overall prevalence of 67.4%among digital screen users.CONCLUSION:There is a significant association between prolonged use of digital screens and clinical markers of dry eye signs and symptoms.
基金co-supported by China Postdoctoral Science Foundation (20090461314)
文摘Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by using the digital grayscale modulation method. The infrared image modulation model of a digital micro-mirror device （DMD） is established and then the infrared scene simulator prototype which is based on DMD grayscale modulation is developed. To evaluate its main parameters such as resolution, contrast, minimum temperature difference, gray scale, various DMD subsystems such as signal decoding, image normalization, synchronization drive, pulse width modulation （PWM） and DMD chips are designed. The infrared scene simulator is tested on a certain infrared missile seeker. The test results show preliminarily that the infrared scene simulator has high gray scale, small geometrical distortion and highly resolvable imaging resolution and contrast and yields high-fidelity images, thus being able to meet the requirements for the infrared scene simulation inside a laboratory.
基金The study was funded by the National Key Technologies R&D Program of China(2018YFC0114800 and 2017YFC0109900)the Natural Science Foundation of China(NSFC)(61405238)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20141206)the Key Technologies R&D Program of Jiangsu Province(BE2018666).
文摘Structured illumination microscopy(SIM)is a promising super-resolution technique for imaging subcellular structures and dynamics due to its compatibility with most commonly usedffuorescent labeling methods.Structured illumination can be obtained by either laser interference or projection of fringe patterns.Here,we proposed a fringe projector composed of a compact multiwavelength LEDs module and a digital micromirror device(DMD)which can be directly attached to most commercial invertedffuorescent microscopes and update it into a SIM system.The effects of the period and duty cycle of fringe patterns on the modulation depth of the structured lightfield were studied.With the optimized fringe pattern,1:6×resolution improvement could be obtained with high-end oil objectives.Multicolor imaging and dynamics of subcellular organelles in live cells were also demonstrated.Our method provides a low-cost solution for SIM setup to expand its wide range of applications to most research labs in thefield of life science and medicine.
基金Supported by the Natural Science Foundation of Beijing under Grant Nos 2162033 and 7182091the National Natural Science Foundation of China under Grant No 21627813
文摘We present a digital micromirror device（DMD） based superpixel method for focusing light through scattering media by modulating the complex field of incident light. Firstly, we numerically and experimentally investigate focusing light through a scattering sample using the superpixel methods with different target complex fields.Then, single-point and multiple-point focusing experiments are performed using this superpixel-based complex modulation method. In our experiment, up to 71.5% relative enhancement is realized. The use of the DMDbased superpixel method for the control of the complex field of incident light opens an avenue to improve the enhancement of focusing light through scattering media.
基金This work is partially supported by the HKSAR Innovation and Technology Commission(ITC)Innovation and Technology Fund(ITF),ITS/179/16FP,as well as the HKSAR Research Grants Council,General Research Fund,Project No.14202815.
文摘An ultrafast spectrum programmable femtosecond laser may enhance the performance of a wide variety of scientific applications,e.g.,multi-photon imaging.In this paper,we report a digital micromirror device(DMD)-based ultrafast pulse shaper,i.e.,DUPS,for femtosecond laser arbitrary amplitude shaping-the first time a programmable binary device reported to shape the amplitudes of ultrafast pulses spectrum at up to 32 kHz rate over a broad wavelength range.The DUPS is highly effcient,compact,and low cost based on the use of a DMD in combination with a transmission grating.Spatial and temporal dispersion introduced by the DUPS is compensated by a quasi-4-f setup and a grating pair,respectively.Femtosecond pulses with arbitrary spectrum shapes,including rectangular,sawtooth,triangular,double-pulse,and exponential profile,have been demonstrated in our experiments.A feedback operation process is implemented in the DUPS to ensure a robust and repeatable shaping process.The total effciency of the DUPS for amplitude shaping is measured to be 27%.
基金supported by the National Natural Science Foundation of China(Nos.61002013 and 11504435)the Natural Science Foundation of Hubei Province(No.2014CFA051)+1 种基金the Key Technology R&D Program of Hubei Province(No.2015BCE048)the Fundamental Research Funds for the Central Universities,South-Central University for Nationalities(Nos.CZY13034,CZW15055 and CZP17026)
文摘A new method which employs compressive sensing(CS) to reconstruct the sparse spectrum is designed and experimentally demonstrated. On the basis of CS theory, the simulation results indicate that the probability of reconstruction is high when the step of the sparsity adaptive matching pursuit algorithm is confirmed as 1. Contrastive analysis for four kinds of commonly used measurement matrices: part Hadamard, Bernoulli, Toeplitz and Circular matrix, has been conducted. The results illustrate that the part Hadamard matrix has better performance of reconstruction than the other matrices. The experimental system of the spectral compression reconstruction is mainly based on the digital micro-mirror device(DMD). The experimental results prove that CS can reconstruct sparse spectrum well under the condition of 50% sampling rate. The system error 0.0781 is obtained, which is defined by the average value of the 2-norm. Furthermore, the proposed method shows a dominant ability to discard redundancy.
基金supported by the Doctoral Program of Higher Education Research Fund (No.1101.01.001.672)
文摘All-optical analog-to-digital conversion (ADC) has been extensively researched to break through the inherently limited operating speed of electronic devices. In this paper, we use the photonic crystal fiber (PCF) for time-stretch (TS) analog-to-digital (A/D) conversion system through generating low noise, linear chirp distribution and flat super-continuum (SC). Based on the radio frequency (RF) analog signal modulated to the linearly chirped super-continuum, the large-dispersion photonic crystal fiber is used for time-domain stretching.
基金The European Union’s regional development funds for Sweden
文摘Research is currently ongoing to investigate the use of assistive technology by people with mild dementia to support independent living at home. The aim of this study was to describe professional caregivers’ perceptions on the prerequisites for and consequences of people with mild dementia using a digital photo diary to facilitate their talks about daily events with their family members. A questionnaire was sent out to 582 participants (response rate 70.1%) to elucidate the professional caregivers’ perceptions on the use of the digital photo diary. The questionnaire contained both quantitative and qualitative data and was analyzed with descriptive statistics, factor analysis, multivariate analysis of covariance and qualitative content analysis. This study reports the results related to prerequisites and consequences of using the photo diary. The results from the factor analysis revealed four factors: Trust, Vulnerability, Dependency/Independency and Control. The qualitative content analysis resulted in five categories: Immediate implementation after receiving a diagnose is required, Relatives’ participation is a necessity, Strengthened self-esteem and meaningful everyday life, Increased alienation and a feeling of isolation and Assistive digital devices provide opportunities. The theme was interpreted as: Personalization and the preservation of dignity. The conclusion that can be drawn from this study is that the participants had an overall positive view of the usage of this specific digital photo diary for people suffering from dementia, but rigorous considerations needs before implementation of the device and regularly follow ups if dignity is to be maintained for people with dementia.
基金This work was supported by National Natural Science Foundation of China(91850202,61775085,11774256)Natural Science Foundation of Guangdong Province(2016A030312010,2020A1515010958)Science and Technology Innovation Commission of Shenzhen(KQTD2017033011044403,ZDSYS201703031605029).
文摘Digital holography has high potentials for future 3D imaging and display technology.We present a method for a dynamic full-color digital holographic 3D display on single digital micro-mirror device(DMD)with full-color,high-speed and high-fidelity characteristics.We combine the square regions of adjacent micro-mirrors into super-pixels that can modulate amplitude and phase independently.Gray images are achieved by amplitude modulation and precise positioning of each color is achieved by phase modulation.The proposed method realizes a full-color imaging based on the three primary colors and achieves measured structural similarity of more than 88%and color similarity of more than 98%,while retaining the high switch speed of 9 kHz,thus achieving dynamic full-color 3D display on charge-coupled device(CCD).
基金supported by the National Natural SciencFoundation of China(Nos.U1636125,61601027)
文摘For the performance issues of satellite transceivers suffering passive intermodulation interference,a novel and effective digital suppression algorithm is presented in this paper.In contrast to analog approaches,digital passive intermodulation（PIM） suppression approaches can be easily reconfigured and therefore are highly attractive for future satellite communication systems.A simplified model of nonlinear distortion from passive microwave devices is established in consideration of the memory effect.The multiple high-order PIM products falling into the receiving band can be described as a bilinear predictor function.A suppression algorithm based on a bilinear polynomial decorrelated adaptive filter is proposed for baseband digital signal processing.In consideration of the time-varying characteristics of passive intermodulation,this algorithm can achieve the rapidness of online interference estimation and low complexity with less consumption of resources.Numerical simulation results show that the algorithm can effectively compensate the passive intermodulation interference,and achieve a high signal-to-interference ratio gain.
文摘As we all know,eyes are the windows of our souls.They make us see the colorful world and understand others’feelings.However,by①the wide use of digital devices like smartphones and computers,many of us are facing eye problems.So,it's important to protect our eyes。
基金Supported by the National High Technology Research and Development Program of China(″863″Program)(2007AA01Z338)the National Science Foundation for Post-doctoral Scientists of China(20080441051)the Jiangsu Province Science Foundation for Post-doctoral Scientists(0802014c)~~
文摘Based on the helix rotating screen and the digital micro-mirror device （DMD）, the former proto of volumetric-swept display system is improved. The 3-D display system adopting a helix rotating screen to construct an imaging space meliorate the defects, such as the smaller image space, the fewer voxels and the severer voxel overlap dead zone caused by planar rotating screen. DMD with spatial light modular （SLM） technology increases the transmission bandwidth of 3-D data in the voxel activation subsystem and activate multi-voxel once time. The volumetric-swept system based on helix rotating screen and DMD is developed. The experimental results show that the image space, the vision dead zone, the voxels on slice, and the voxel activation capacity of the designed proto are superior to the plane rotating screen system.
基金National Natural Science Foundation of China(61635004,61775069)Technology Innovation Program of Hubei Province of China(2018AAA037)。
文摘A high-efficiency inverse design of"digital"subwavelength nanophotonic devices using the adjoint method is proposed.We design a single-mode 3dB power divider and a dual-mode demultiplexer to demonstrate the efficiency of the proposed inverse design approach,called the digitized adjoint method,for single-and dual-object optimization,respectively.The optimization comprises three stages:1)continuous variation for an"analog"pattern;2)forced permittivity biasing for a"quasi-digital"pattern;and 3)a multilevel digital pattern.Compared with the conventional brute-force method,the proposed method can improve design efficiency by about five times,and the performance optimization can reach approximately the same level.The method takes advantages of adjoint sensitivity analysis and digital subwavelength structure and creates a new way for the efficient and high-performance design of compact digital subwavelength nanophotonic devices,which could overcome the efficiency bottleneck of the brute-force method,which is restricted by the number of pixels of a digital pattern,and improve the device performance by extending a conventional binary pattern to a multilevel one.
基金co-supported by National Natural Science Foundation of China(Nos.61922011 and 61675016)the Fundamental Research Funds for the Central Universities。
文摘Conventional semi-active laser guidance takes advantage of the laser designator to illuminate the stable and uniform laser spot on target precisely.The seeker collects the reflected light by a quadrant detector and outputs the relative position information to guide the missile to the illuminating laser spot.However,the designation and guidance accuracy could be jeopardized by the randomly drifting of laser spot caused by the instability of designation platform and air turbulence.In this work,ghost imaging technique is adapted to a quadrant detector semi-active seeker by utilizing structured illumination on the target.With a series of structured illumination masks,the signals from the quadrant detector are multiplexed to perform calculation of the target relative position as well as image reconstruction of the illuminated area simultaneously.Automatic target recognition methods could be further applied to the reconstructed image to calculate the designating error and correct the guidance.The results of simulation and experiment demonstrate that the proposed method could improve the guidance accuracy in many circumstances which would lead to attacking deviation if conventional semi-active laser guidance is used.
基金funded by the National Natural Science Foundation of China(62125504,61827825,and 31901059)Zhejiang Provincial Ten Thousand Plan for Young Top Talents(2020R52001)Open Project Program of Wuhan National Laboratory for Optoelectronics(2021WNLOKF007).
文摘Structured illumination microscopy(SIM)achieves super-resolution(SR)by modulating the high-frequency information of the sample into the passband of the optical system and subsequent image reconstruction.The traditional Wiener-filtering-based reconstruction algorithm operates in the Fourier domain,it requires prior knowledge of the sinusoidal illumination patterns which makes the time-consuming procedure of parameter estimation to raw datasets necessary,besides,the parameter estimation is sensitive to noise or aberration-induced pattern distortion which leads to reconstruction artifacts.Here,we propose a spatial-domain image reconstruction method that does not require parameter estimation but calculates patterns from raw datasets,and a reconstructed image can be obtained just by calculating the spatial covariance of differential calculated patterns and differential filtered datasets(the notch filtering operation is performed to the raw datasets for attenuating and compensating the optical transfer function(OTF)).Experiments on reconstructing raw datasets including nonbiological,biological,and simulated samples demonstrate that our method has SR capability,high reconstruction speed,and high robustness to aberration and noise.
