In the study of the application of MODIS satellite remote sensing data to earthquake prediction, the paper puts forward for the first time a quantitative method to estimate the ratio for the pixels with abnormal brigh...In the study of the application of MODIS satellite remote sensing data to earthquake prediction, the paper puts forward for the first time a quantitative method to estimate the ratio for the pixels with abnormal brightness temperature (BT) increase and a preliminary scheme for cloud removal. The principle is that, firstly, the cloudless data observed by the same satellite at the same period of time but in different days (usually 1 day to 3 days) are mosaiced to get high ratio of clear sky, and then the BT variation curve and mean square difference (MSD) of each pixel are calculated with the data from the covered area to determine daily whether the BT data of the day is normal or not at a certain pixel by using double the MSD as the criterion. The ratio for the pixels with abnormal BT increase can be calculated by dividing the total number of abnormal pixels with the total pixels of the whole area. Analysis on a series of recent earthquakes in the Taiwan Region shows that the ratio for pixels with abnormal BT increase, which normally undulates around zero, has a sudden enhancement 1 day to 20 days before medium-strong earthquakes. It is expected that a new method for identifying earthquake auspice could be found through special studies in regions with frequent seismic activity by analyzing the change of the ratio for the pixels with abnormal BT increase from MODIS satellite remote sensing infrared (IR) information from which the effect of clouds has been removed to a certain extent.展开更多
A variation pixels identification method was proposed aiming at depressing the effect of variation pixels, which dilates the theoretical hyperspectral data simplex and misguides volume evaluation of the simplex. With ...A variation pixels identification method was proposed aiming at depressing the effect of variation pixels, which dilates the theoretical hyperspectral data simplex and misguides volume evaluation of the simplex. With integration of both spatial and spectral information, this method quantitatively defines a variation index for every pixel. The variation index is proportional to pixels local entropy but inversely proportional to pixels kernel spatial attraction. The number of pixels removed was modulated by an artificial threshold factor α. Two real hyperspectral data sets were employed to examine the endmember extraction results. The reconstruction errors of preprocessing data as opposed to the result of original data were compared. The experimental results show that the number of distinct endmembers extracted has increased and the reconstruction error is greatly reduced. 100% is an optional value for the threshold factor α when dealing with no prior knowledge hyperspectral data.展开更多
We present a novel scheme for embedding secret data into a binary image without introducing noticeable artifacts. Unlike some block-based methods, the proposed scheme encodes the secret bits directly into boundary pix...We present a novel scheme for embedding secret data into a binary image without introducing noticeable artifacts. Unlike some block-based methods, the proposed scheme encodes the secret bits directly into boundary pixels by checking each pixel of the cover image in a pseudo-random order for embedding eligibility. A set of rules ensures correct identification of data-carrying pixels in blind extraction. The proposed scheme does not generate isolated dots, and can incorporate various coding methods such as matrix encoding to further improve the embedding performance. It is shown that up to one fourth of the boundary pixels may be used to carry secret data. Experimental results indicate that the method can achieve good visual quality with fairly large data capacity.展开更多
By using the MOS-based model established in this paper, the physical process of photoelectron generation, transfer,and storage in the four-transistor active pixel sensor(4 T-APS) pixels can be simulated in SPICE envir...By using the MOS-based model established in this paper, the physical process of photoelectron generation, transfer,and storage in the four-transistor active pixel sensor(4 T-APS) pixels can be simulated in SPICE environment. The variable capacitance characteristics of double junctions in pinned photodiodes(PPDs) and the threshold voltage difference formed by channel nonuniform doping in transfer gates(TGs) are considered with this model. The charge transfer process of photogenerated electrons from PPDs to the floating diffusion(FD) is analyzed, and the function of nonuniform doping of TGs in suppressing charge injection back to PPDs is represented with the model. The optical and electrical characteristics of all devices in the pixel are effectively combined with the model. Moreover, the charge transfer efficiency and the voltage variation in PPD can be described with the model. Compared with the hybrid simulation in TCAD and the Verilog-A simulation in SPICE, this model has higher simulation efficiency and accuracy, respectively. The effectiveness of the MOS-based model is experimentally verified in a 3 μm test pixel designed in 0.11 μm CIS process.展开更多
To improve the full-well capacity and linear dynamic range of CMOS image sensor,a special finger-shaped pinned photodiode(PPD)is designed.In terms of process,the first N-type ion implantation of the PPD N buried layer...To improve the full-well capacity and linear dynamic range of CMOS image sensor,a special finger-shaped pinned photodiode(PPD)is designed.In terms of process,the first N-type ion implantation of the PPD N buried layer is extended under the transfer gate,thereby increasing the PPD capacitance.Based on TCAD simulation,the width and spacing of PPD were precisely adjusted.A high full-well capacity pixel design with a pixel size of 6×6μm^2 is realized based on the 0.18μm CMOS process.The simulation results indicate that the pixel with the above structure and process has a depletion depth of 2.8μm and a charge transfer efficiency of 100%.The measurement results of the test chip show that the full-well capacity can reach 68650 e–.Compared with the conventional structure,the proposed PPD structure can effectively improve the full well capacity of the pixel.展开更多
The event-based vision sensor(EVS),which can generate efficient spiking data streams by exclusively detecting motion,exemplifies neuromorphic vision methodologies.Generally,its inherent lack of texture features limits...The event-based vision sensor(EVS),which can generate efficient spiking data streams by exclusively detecting motion,exemplifies neuromorphic vision methodologies.Generally,its inherent lack of texture features limits effectiveness in complex vision processing tasks,necessitating supplementary visual information.However,to date,no event-based hybrid vision solution has been developed that preserves the characteristics of complete spike data streams to support synchronous computation architectures based on spiking neural network(SNN).In this paper,we present a novel spike-based sensor with digitized pixels,which integrates the event detection structure with the pulse frequency modulation(PFM)circuit.This design enables the simultaneous output of spiking data that encodes both temporal changes and texture information.Fabricated in 180 nm process,the proposed sensor achieves a resolution of 128×128,a maximum event rate of 960 Meps,a grayscale frame rate of 117.1 kfps,and a measured power consumption of 60.1 mW,which is suited for high-speed,low-latency,edge SNNbased vision computing systems.展开更多
By using a pixelized Nal（T1） crystal array coupled to a R2486 PSPMT, the characteristics of the array and of a single pixel, such as the light output, energy resolution, peak-to-valley ratio （P/V） and imaging perf...By using a pixelized Nal（T1） crystal array coupled to a R2486 PSPMT, the characteristics of the array and of a single pixel, such as the light output, energy resolution, peak-to-valley ratio （P/V） and imaging performance of the detector were studied. The pixel size of the NaI（TI） scintillation pixel array is 2 mm×2 mm×5 mm. There are in total 484 pixels in a 22×22 matrix. In the pixel spectrum an average peak-to-valley ratio （P/V） of 16 was obtained. In the image of all the pixels, good values for the Peak-to- Valley ratios could be achieved, namely a mean of 17, a maximum of 45 and the average peak FWHM （the average value of intrinsic spatial resolution） of 2.3 mm. However, the PSPMT non-uniform response and the scintillation pixels array inhomogeneities degrade the imaging performance of the detector.展开更多
Brazil’s deforestation monitoring integrates accuracy and current monitoring for land use and land cover applications.Regular monitoring of deforestation and non-deforestation requires Sentinel-2 multispectral satell...Brazil’s deforestation monitoring integrates accuracy and current monitoring for land use and land cover applications.Regular monitoring of deforestation and non-deforestation requires Sentinel-2 multispectral satellite images of several bands at various frequencies,the mix of high-and low-resolution images that make object classification difficult because of the mixed pixel problem.Accuracy is impacted by the mixed pixel problem,which occurs when pixels belong to different classes and makes detection challenging.To identify mixed pixels,Band Math is used to merge numerous bands to generate a new band NDVI.Thresholding is used to analyze the edges of deforested and non-deforested areas.Segmentation is then used to analyze the pixels which helps to identify the number of mixed pixels to compute the deforested and non-deforested areas.Segmented image pixels are used to categorize the deforestation of the Brazilian Amazon Forest between 2019 and 2023.Verify how many pixels are mixed to improve accuracy and identify mixed pixel issues;compare the mixed and pure pixels of fuzzy clustering with the subtracted morphological image pixels.With the help of segmentation and clustering researchers effectively validate mixed pixels in a specific area.The proposed methodology is easy to analyze and helpful for an appropriate calculation of deforested and non-deforested areas.展开更多
X-ray detectors show potential applications in medical imaging,materials science,and nuclear energy.To achieve high detection efficiency and spatial resolution,many conventional semiconductor materials,such as amorpho...X-ray detectors show potential applications in medical imaging,materials science,and nuclear energy.To achieve high detection efficiency and spatial resolution,many conventional semiconductor materials,such as amorphous selenium,cadmium telluride zinc,and perovskites,have been utilized in direct conversion X-ray detectors.However,these semiconductor materials are susceptible to temperature-induced performance degradation,crystallization,delamination,uneven lattice growth,radiation damage,and high dark current.This study explores a new approach by coupling an FC40 electronic fluorinated liquid with a specialized high-resolution and high-readout-speed complementary metal-oxide-semiconductor(CMOS)pixel array,specifically the Topmetal II−chip,to fabricate a direct conversion X-ray detector.The fluorinated liquid FC40(molecular formula:C_(21)F_(48)N_(2))is an electronic medium that is minimally affected by temperature and displays no issues with uniform conductivity.It exhibits a low dark current and minimal radiation damage and enables customizable thickness in X-ray absorption.This addresses the limitations inherent in conventional semiconductor-based detectors.In this study,simple X-ray detector imaging tests were conducted,demonstrating the excellent coupling capability between FC40 electronic fluorinated liquid and CMOS chips by the X-ray detector.A spatial resolution of 4.0 lp/mm was measured using a striped line par card,and a relatively clear image of a cockroach was displayed in the digital radiography imaging results.Preliminary test results indicated the feasibility of fabricating an X-ray detector by combining FC40 electronic fluorinated liquid and CMOS chips.Owing to the absence of issues related to chip-material coupling,a high spatial resolution could be achieved by reducing the chip pixel size.This method presents a new avenue for studies on novel liquid-based direct conversion X-ray detectors.展开更多
目的:探讨玫瑰痤疮患者采用低能量Pixel调Q像束激光与米诺环素联合治疗后红斑情况及面部功能改善情况。方法:研究对象选自于2020年3月-2023年7月在上海交通大学医学院苏州九龙医院接受治疗的玫瑰痤疮患者110例,并分为对照组和观察组,每...目的:探讨玫瑰痤疮患者采用低能量Pixel调Q像束激光与米诺环素联合治疗后红斑情况及面部功能改善情况。方法:研究对象选自于2020年3月-2023年7月在上海交通大学医学院苏州九龙医院接受治疗的玫瑰痤疮患者110例,并分为对照组和观察组,每组例数均为55例,分组方法为随机数字表法。对照组给予盐酸米诺环素片,在对照组患者治疗的基础上,采用低能量Pixel调Q像束激光对观察组患者进行治疗。两组治疗时间均为6周。比较两组临床疗效(治疗6周后),玫瑰痤疮情况、整体病情、p38丝裂原活化蛋白激酶(p38 mitogen activated protein kinase,p38MAPK)通路蛋白、生活质量、红斑情况、面部功能、炎性因子(治疗前、治疗6周后),不良反应(治疗期间)。结果:治疗6周后,观察组总有效率高于对照组(76.36%vs.54.55%,P<0.05)。与治疗前比较,两组治疗6周后的玫瑰痤疮医师全球评分(Patient's global assessment,PGA)、整体病情评估(Investigator global assessment,IGA)、皮肤病生活质量量表(Dermatology life quality index,DLQI)评分、红斑评估量表(Clinician′s erythema assessment,CEA)评分、皮损区红斑指数(Erythema index,EI)、经皮水分丢失(Trans epidermal water loss,TEWL)、皮肤酸碱度(Pondus Hydrogenii,pH)值、炎性因子及p38MAPK通路蛋白相关因子水平均降低,且相比于对照组,观察组更低;两组角质层含水量均升高,且相比于对照组,观察组更高(P<0.05)。观察组和对照组治疗期间的不良反应发生率比较差异无统计学意义(P>0.05)。结论:玫瑰痤疮患者经低能量Pixel调Q像束激光联合米诺环素治疗后,其相关临床症状可得到有效缓解,炎症反应得以减轻,并可调节p38MAPK信号通路蛋白的表达,进一步可促进患者红斑情况及面部功能的改善,进而促使患者生活质量及临床疗效得以提高,且具有良好的安全性。展开更多
With the development of the micro/nanolithography, the optic-optic or optic-electronic modulation devices with different pixel shapes and sizes can be used for three-dimensional （3D） dynamical holographic display. T...With the development of the micro/nanolithography, the optic-optic or optic-electronic modulation devices with different pixel shapes and sizes can be used for three-dimensional （3D） dynamical holographic display. The influence of different parameters of the modulation devices on the image quality of the 3D reconstructed object is analyzed for two cases： the phase-only computer-generated holography （CGH） and the complex amplitude CGH. The results quantitatively show that the pixel shape of the modulation devices will affect the quality of the holographic image.展开更多
Currently,the main idea of iterative rendering methods is to allocate a fixed number of samples to pixels that have not been fully rendered by calculating the completion rate.It is obvious that this strategy ignores t...Currently,the main idea of iterative rendering methods is to allocate a fixed number of samples to pixels that have not been fully rendered by calculating the completion rate.It is obvious that this strategy ignores the changes in pixel values during the previous rendering process,which may result in additional iterative operations.展开更多
A new algorithm for decomposition of mixed pixels based on orthogonal bases of data space is proposed in this paper. It is a simplex-based method which extracts endmembers sequentially using computations of largest si...A new algorithm for decomposition of mixed pixels based on orthogonal bases of data space is proposed in this paper. It is a simplex-based method which extracts endmembers sequentially using computations of largest simplex volumes. At each searching step of this extraction algorithm, searching for the simplex with the largest volume is equivalent to searching for a new orthogonal basis which has the largest norm. The new endmember corresponds to the new basis with the largest norm. This algorithm runs very fast and can also avoid the dilemma in traditional simplex-based endmember extraction algorithms, such as N-FINDR, that it generally produces different sets of final endmembers if different initial conditions are used. Moreover, with this set of orthogonal bases, the proposed algorithm can also determine the proper number of endmembers and finish the unmixing of the original images which the traditional simplex-based algorithms cannot do by themselves. Experimental results of both artificial simulated images and practical remote sensing images demonstrate the algorithm proposed in this paper is a fast and accurate algorithm for the decomposition of mixed pixels.展开更多
Maritime target recognition and image perception enhancement are gradually being promoted and applied in ocean engineering. This paper proposes the attentional multi-pixel fusion(AMF) algorithm for the intelligent nav...Maritime target recognition and image perception enhancement are gradually being promoted and applied in ocean engineering. This paper proposes the attentional multi-pixel fusion(AMF) algorithm for the intelligent navigation of unmanned surface vessels(USVs). The algorithm preprocesses the image pixel matrix in blocks, computes the mapping between regional and full-pixel matrices, and adaptively equalizes the mapping weights via a Gaussian-fuzzy matrix.This approach guarantees the preservation of the target contour and texture information. Compared with five classic enhancement algorithms, the AMF algorithm improves the peak signal-to-noise ratio(PSNR) and structural similarity index(SSIM). Experimental validation via YOLOv8 for maritime target detection demonstrates 2.1% and 2.4%improvements in the evaluation indices over training on 4000 original images, with shorter training times and lower confusion rates. In maritime target ranging, the AMF algorithm, coupled with the ISR method, exhibits the lowest improved stereo ranging mean absolute error and standard deviation values and higher similarity between the regional and full-pixel matrices. In summary, the AMF algorithm excels in target detection and ranging, offering promising applications in ocean engineering, such as marine resource exploitation, path planning, and intelligent collaboration among unmanned vessels.展开更多
The surface velocity is one of the most important characteristics of glaciers.Monitoring and mapping glacier movements are of great significance for the studies of sea-level rise,glacier mass balance and dynamics,glob...The surface velocity is one of the most important characteristics of glaciers.Monitoring and mapping glacier movements are of great significance for the studies of sea-level rise,glacier mass balance and dynamics,global warming,and the management of freshwater resources.It is also essential for the early warnings of hazards caused by ice avalanches.SAR imaging geodesy has been developed for measuring glacier velocity,especially the pixel-offset tracking method.This paper introduces some basic concepts of glaciology and principles of various SAR imaging geodesy methods,with a detailed presentation about the developments in the applications of the pixel-offset tracking method.Finally,the challenges and future prospects of SAR imaging geodesy in glacier monitoring are discussed.展开更多
The types and structures of inorganic pores are key factors in evaluations of the reservoir space and distribution characteristics of shale oil and gas.However,quantitative identification methods for pores of differen...The types and structures of inorganic pores are key factors in evaluations of the reservoir space and distribution characteristics of shale oil and gas.However,quantitative identification methods for pores of different inorganic components have not yet been fully developed.For this reason,a quantitative characterization method of inorganic pores using pixel information was proposed in this study.A machine learning algorithm was used to assist the field emission scanning electron microscopy(FE-SEM)image processing of shale to realize the accurate identification and quantitative characterization of inorganic pores on the surface of high-precision images of shale with a small view.Moreover,large-view image splicing technology,combined with quantitative evaluation of minerals by scanning electron microscopy(QEMSCAN)image joint characterization technology,was used to accurately analyze the distribution characteristics of inorganic pores under different mineral components.The quantitative methods of pore characteristics of different inorganic components under the pixel information of shale were studied.The results showed that(1)the Waikato Environment for Knowledge Analysis(WEKA)machine learning model can effectively identify and extract shale mineral components and inorganic pore distribution,and the large-view FE-SEM images are representative of samples at the 200μm×200μm view scale,meeting statistical requirements and eliminating the influence of heterogeneity;(2)the pores developed by different mineral components of shale had obvious differences,indicating that the development of inorganic pores is highly correlated with the properties of shale minerals themselves;and(3)the pore-forming ability of different mineral components is calculated by the quantitative method of single component pore-forming coefficient.Chlorite showed the highest pore-forming ability,followed by(in descending order)illite,pyrite,calcite,dolomite,albite,orthoclase,quartz,and apatite.This study contributes to advancing our understanding of inorganic pore characteristics in shale.展开更多
Automatic segmentation and recognition of content and element information in color geological map are of great significance for researchers to analyze the distribution of mineral resources and predict disaster informa...Automatic segmentation and recognition of content and element information in color geological map are of great significance for researchers to analyze the distribution of mineral resources and predict disaster information.This article focuses on color planar raster geological map(geological maps include planar geological maps,columnar maps,and profiles).While existing deep learning approaches are often used to segment general images,their performance is limited due to complex elements,diverse regional features,and complicated backgrounds for color geological map in the domain of geoscience.To address the issue,a color geological map segmentation model is proposed that combines the Felz clustering algorithm and an improved SE-UNet deep learning network(named GeoMSeg).Firstly,a symmetrical encoder-decoder structure backbone network based on UNet is constructed,and the channel attention mechanism SENet has been incorporated to augment the network’s capacity for feature representation,enabling the model to purposefully extract map information.The SE-UNet network is employed for feature extraction from the geological map and obtain coarse segmentation results.Secondly,the Felz clustering algorithm is used for super pixel pre-segmentation of geological maps.The coarse segmentation results are refined and modified based on the super pixel pre-segmentation results to obtain the final segmentation results.This study applies GeoMSeg to the constructed dataset,and the experimental results show that the algorithm proposed in this paper has superior performance compared to other mainstream map segmentation models,with an accuracy of 91.89%and a MIoU of 71.91%.展开更多
Metamaterials have exotic physical properties that rely on the construction of their underlying architecture.However,the physical properties of conventional mechanical metamaterials are permanently programmed into the...Metamaterials have exotic physical properties that rely on the construction of their underlying architecture.However,the physical properties of conventional mechanical metamaterials are permanently programmed into their periodic interconnect configurations,resulting in their lack of modularity,scalable fabrication,and programmability.Mechanical metamaterials typically exhibit a single extraordinary mechanical property or multiple extraordinary properties coupled together,making it difficult to realize multiple independent extraordinary mechanical properties.Here,the pixel mechanics metamaterials(PMMs)with multifunctional and reprogrammable properties are developed by arraying uncoupled constrained individual modular mechanics pixels(MPs).The MPs enable controlled conversion between two extraordinary mechanical properties(multistability and compression-torsion coupling deformation).Each MP exhibits 32 independent and reversible room temperature programming configurations.In addition,the programmability of metamaterials is further enhanced by shape memory polymer(SMP)and 4D printing,greatly enriching the design freedom.For the PMM consisting of m×n MPs,it has 32(m×n)independent room temperature programming configurations.The application prospects of metamaterials in the vibration isolation device and energy absorption device with programmable performance have been demonstrated.The vibration isolation frequencies of the MP before and after programming were[0 Hz-5.86 Hz],[0 Hz-13.67 Hz and 306.64 Hz-365.23 Hz].The total energy absorption of the developed PMM can be adjusted controllably in the range of 1.01 J-3.91 J.Six standard digital logic gates that do not require sustained external force are designed by controlling the closure between the modules.This design paradigm will facilitate the further development of multifunctional and reprogrammable metamaterials.展开更多
基金This project was sponsored by the Science and Technology Programof Sichuan Province (05SG031-004)
文摘In the study of the application of MODIS satellite remote sensing data to earthquake prediction, the paper puts forward for the first time a quantitative method to estimate the ratio for the pixels with abnormal brightness temperature (BT) increase and a preliminary scheme for cloud removal. The principle is that, firstly, the cloudless data observed by the same satellite at the same period of time but in different days (usually 1 day to 3 days) are mosaiced to get high ratio of clear sky, and then the BT variation curve and mean square difference (MSD) of each pixel are calculated with the data from the covered area to determine daily whether the BT data of the day is normal or not at a certain pixel by using double the MSD as the criterion. The ratio for the pixels with abnormal BT increase can be calculated by dividing the total number of abnormal pixels with the total pixels of the whole area. Analysis on a series of recent earthquakes in the Taiwan Region shows that the ratio for pixels with abnormal BT increase, which normally undulates around zero, has a sudden enhancement 1 day to 20 days before medium-strong earthquakes. It is expected that a new method for identifying earthquake auspice could be found through special studies in regions with frequent seismic activity by analyzing the change of the ratio for the pixels with abnormal BT increase from MODIS satellite remote sensing infrared (IR) information from which the effect of clouds has been removed to a certain extent.
基金Projects(61571145,61405041)supported by the National Natural Science Foundation of ChinaProject(2014M551221)supported by the China Postdoctoral Science Foundation,China+3 种基金Project(LBH-Z13057)supported by the Heilongjiang Postdoctoral Science Found,ChinaProject(ZD201216)supported by the Key Program of Heilongjiang Natural Science Foundation,ChinaProject(RC2013XK009003)supported by the Program of Excellent Academic Leaders of Harbin,ChinaProject(HEUCF1508)supported by the Fundamental Research Funds for the Central Universities,China
文摘A variation pixels identification method was proposed aiming at depressing the effect of variation pixels, which dilates the theoretical hyperspectral data simplex and misguides volume evaluation of the simplex. With integration of both spatial and spectral information, this method quantitatively defines a variation index for every pixel. The variation index is proportional to pixels local entropy but inversely proportional to pixels kernel spatial attraction. The number of pixels removed was modulated by an artificial threshold factor α. Two real hyperspectral data sets were employed to examine the endmember extraction results. The reconstruction errors of preprocessing data as opposed to the result of original data were compared. The experimental results show that the number of distinct endmembers extracted has increased and the reconstruction error is greatly reduced. 100% is an optional value for the threshold factor α when dealing with no prior knowledge hyperspectral data.
基金Project supported by the National Natural Science Foundation of China （Grant Nos.60372090, 60502039）, and the Key Project of Shanghai Municipality for Basic Research （Grant No.04JC14037）
文摘We present a novel scheme for embedding secret data into a binary image without introducing noticeable artifacts. Unlike some block-based methods, the proposed scheme encodes the secret bits directly into boundary pixels by checking each pixel of the cover image in a pseudo-random order for embedding eligibility. A set of rules ensures correct identification of data-carrying pixels in blind extraction. The proposed scheme does not generate isolated dots, and can incorporate various coding methods such as matrix encoding to further improve the embedding performance. It is shown that up to one fourth of the boundary pixels may be used to carry secret data. Experimental results indicate that the method can achieve good visual quality with fairly large data capacity.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61874085)the Postdoctoral Research Funding Project of Shaanxi Province,China (Grant No. 2018BSHEDZZ41)。
文摘By using the MOS-based model established in this paper, the physical process of photoelectron generation, transfer,and storage in the four-transistor active pixel sensor(4 T-APS) pixels can be simulated in SPICE environment. The variable capacitance characteristics of double junctions in pinned photodiodes(PPDs) and the threshold voltage difference formed by channel nonuniform doping in transfer gates(TGs) are considered with this model. The charge transfer process of photogenerated electrons from PPDs to the floating diffusion(FD) is analyzed, and the function of nonuniform doping of TGs in suppressing charge injection back to PPDs is represented with the model. The optical and electrical characteristics of all devices in the pixel are effectively combined with the model. Moreover, the charge transfer efficiency and the voltage variation in PPD can be described with the model. Compared with the hybrid simulation in TCAD and the Verilog-A simulation in SPICE, this model has higher simulation efficiency and accuracy, respectively. The effectiveness of the MOS-based model is experimentally verified in a 3 μm test pixel designed in 0.11 μm CIS process.
基金supported by the Tianjin Key Laboratory of Imaging and Sensing Microelectronic Technology。
文摘To improve the full-well capacity and linear dynamic range of CMOS image sensor,a special finger-shaped pinned photodiode(PPD)is designed.In terms of process,the first N-type ion implantation of the PPD N buried layer is extended under the transfer gate,thereby increasing the PPD capacitance.Based on TCAD simulation,the width and spacing of PPD were precisely adjusted.A high full-well capacity pixel design with a pixel size of 6×6μm^2 is realized based on the 0.18μm CMOS process.The simulation results indicate that the pixel with the above structure and process has a depletion depth of 2.8μm and a charge transfer efficiency of 100%.The measurement results of the test chip show that the full-well capacity can reach 68650 e–.Compared with the conventional structure,the proposed PPD structure can effectively improve the full well capacity of the pixel.
基金supported in part by the National Key Research and Development Program of China(Grant No.2022YFB2804401)the National Natural Science Foundation of China(Grant Nos.62334008,62134004,62404218)+1 种基金the Beijing Natural Science Foundation(Grant No.Z220005)Chinese Academy of Sciences(Grant No.ZDBS-LY-JSC008).
文摘The event-based vision sensor(EVS),which can generate efficient spiking data streams by exclusively detecting motion,exemplifies neuromorphic vision methodologies.Generally,its inherent lack of texture features limits effectiveness in complex vision processing tasks,necessitating supplementary visual information.However,to date,no event-based hybrid vision solution has been developed that preserves the characteristics of complete spike data streams to support synchronous computation architectures based on spiking neural network(SNN).In this paper,we present a novel spike-based sensor with digitized pixels,which integrates the event detection structure with the pulse frequency modulation(PFM)circuit.This design enables the simultaneous output of spiking data that encodes both temporal changes and texture information.Fabricated in 180 nm process,the proposed sensor achieves a resolution of 128×128,a maximum event rate of 960 Meps,a grayscale frame rate of 117.1 kfps,and a measured power consumption of 60.1 mW,which is suited for high-speed,low-latency,edge SNNbased vision computing systems.
基金Supported by National Nature Science Foundation of China (10275063)
文摘By using a pixelized Nal（T1） crystal array coupled to a R2486 PSPMT, the characteristics of the array and of a single pixel, such as the light output, energy resolution, peak-to-valley ratio （P/V） and imaging performance of the detector were studied. The pixel size of the NaI（TI） scintillation pixel array is 2 mm×2 mm×5 mm. There are in total 484 pixels in a 22×22 matrix. In the pixel spectrum an average peak-to-valley ratio （P/V） of 16 was obtained. In the image of all the pixels, good values for the Peak-to- Valley ratios could be achieved, namely a mean of 17, a maximum of 45 and the average peak FWHM （the average value of intrinsic spatial resolution） of 2.3 mm. However, the PSPMT non-uniform response and the scintillation pixels array inhomogeneities degrade the imaging performance of the detector.
文摘Brazil’s deforestation monitoring integrates accuracy and current monitoring for land use and land cover applications.Regular monitoring of deforestation and non-deforestation requires Sentinel-2 multispectral satellite images of several bands at various frequencies,the mix of high-and low-resolution images that make object classification difficult because of the mixed pixel problem.Accuracy is impacted by the mixed pixel problem,which occurs when pixels belong to different classes and makes detection challenging.To identify mixed pixels,Band Math is used to merge numerous bands to generate a new band NDVI.Thresholding is used to analyze the edges of deforested and non-deforested areas.Segmentation is then used to analyze the pixels which helps to identify the number of mixed pixels to compute the deforested and non-deforested areas.Segmented image pixels are used to categorize the deforestation of the Brazilian Amazon Forest between 2019 and 2023.Verify how many pixels are mixed to improve accuracy and identify mixed pixel issues;compare the mixed and pure pixels of fuzzy clustering with the subtracted morphological image pixels.With the help of segmentation and clustering researchers effectively validate mixed pixels in a specific area.The proposed methodology is easy to analyze and helpful for an appropriate calculation of deforested and non-deforested areas.
基金supported by the National Natural Science Foundation of China(No.12235006)the National Key Research and Development Program of China(No.2020YFE0202002.
文摘X-ray detectors show potential applications in medical imaging,materials science,and nuclear energy.To achieve high detection efficiency and spatial resolution,many conventional semiconductor materials,such as amorphous selenium,cadmium telluride zinc,and perovskites,have been utilized in direct conversion X-ray detectors.However,these semiconductor materials are susceptible to temperature-induced performance degradation,crystallization,delamination,uneven lattice growth,radiation damage,and high dark current.This study explores a new approach by coupling an FC40 electronic fluorinated liquid with a specialized high-resolution and high-readout-speed complementary metal-oxide-semiconductor(CMOS)pixel array,specifically the Topmetal II−chip,to fabricate a direct conversion X-ray detector.The fluorinated liquid FC40(molecular formula:C_(21)F_(48)N_(2))is an electronic medium that is minimally affected by temperature and displays no issues with uniform conductivity.It exhibits a low dark current and minimal radiation damage and enables customizable thickness in X-ray absorption.This addresses the limitations inherent in conventional semiconductor-based detectors.In this study,simple X-ray detector imaging tests were conducted,demonstrating the excellent coupling capability between FC40 electronic fluorinated liquid and CMOS chips by the X-ray detector.A spatial resolution of 4.0 lp/mm was measured using a striped line par card,and a relatively clear image of a cockroach was displayed in the digital radiography imaging results.Preliminary test results indicated the feasibility of fabricating an X-ray detector by combining FC40 electronic fluorinated liquid and CMOS chips.Owing to the absence of issues related to chip-material coupling,a high spatial resolution could be achieved by reducing the chip pixel size.This method presents a new avenue for studies on novel liquid-based direct conversion X-ray detectors.
文摘目的:探讨玫瑰痤疮患者采用低能量Pixel调Q像束激光与米诺环素联合治疗后红斑情况及面部功能改善情况。方法:研究对象选自于2020年3月-2023年7月在上海交通大学医学院苏州九龙医院接受治疗的玫瑰痤疮患者110例,并分为对照组和观察组,每组例数均为55例,分组方法为随机数字表法。对照组给予盐酸米诺环素片,在对照组患者治疗的基础上,采用低能量Pixel调Q像束激光对观察组患者进行治疗。两组治疗时间均为6周。比较两组临床疗效(治疗6周后),玫瑰痤疮情况、整体病情、p38丝裂原活化蛋白激酶(p38 mitogen activated protein kinase,p38MAPK)通路蛋白、生活质量、红斑情况、面部功能、炎性因子(治疗前、治疗6周后),不良反应(治疗期间)。结果:治疗6周后,观察组总有效率高于对照组(76.36%vs.54.55%,P<0.05)。与治疗前比较,两组治疗6周后的玫瑰痤疮医师全球评分(Patient's global assessment,PGA)、整体病情评估(Investigator global assessment,IGA)、皮肤病生活质量量表(Dermatology life quality index,DLQI)评分、红斑评估量表(Clinician′s erythema assessment,CEA)评分、皮损区红斑指数(Erythema index,EI)、经皮水分丢失(Trans epidermal water loss,TEWL)、皮肤酸碱度(Pondus Hydrogenii,pH)值、炎性因子及p38MAPK通路蛋白相关因子水平均降低,且相比于对照组,观察组更低;两组角质层含水量均升高,且相比于对照组,观察组更高(P<0.05)。观察组和对照组治疗期间的不良反应发生率比较差异无统计学意义(P>0.05)。结论:玫瑰痤疮患者经低能量Pixel调Q像束激光联合米诺环素治疗后,其相关临床症状可得到有效缓解,炎症反应得以减轻,并可调节p38MAPK信号通路蛋白的表达,进一步可促进患者红斑情况及面部功能的改善,进而促使患者生活质量及临床疗效得以提高,且具有良好的安全性。
基金supported by the National 973 Program of China(Nos.2013CB328801 and 2013CB328806)the National Natural Science Foundation of China(No.61235002)
文摘With the development of the micro/nanolithography, the optic-optic or optic-electronic modulation devices with different pixel shapes and sizes can be used for three-dimensional （3D） dynamical holographic display. The influence of different parameters of the modulation devices on the image quality of the 3D reconstructed object is analyzed for two cases： the phase-only computer-generated holography （CGH） and the complex amplitude CGH. The results quantitatively show that the pixel shape of the modulation devices will affect the quality of the holographic image.
基金supported partially by the National Natural Science Foundation of China(No.U19A2063)the Jilin Provincial Science&Technology Development Program of China(No.20230201080GX)。
文摘Currently,the main idea of iterative rendering methods is to allocate a fixed number of samples to pixels that have not been fully rendered by calculating the completion rate.It is obvious that this strategy ignores the changes in pixel values during the previous rendering process,which may result in additional iterative operations.
基金Supported in part by the National Natural Science Foundation of China (Grant No. 60672116)the National High-Tech Research & Development Program of China (Grant No. 2009AA12Z115)the Shanghai Leading Academic Discipline Project (Grant No. B112)
文摘A new algorithm for decomposition of mixed pixels based on orthogonal bases of data space is proposed in this paper. It is a simplex-based method which extracts endmembers sequentially using computations of largest simplex volumes. At each searching step of this extraction algorithm, searching for the simplex with the largest volume is equivalent to searching for a new orthogonal basis which has the largest norm. The new endmember corresponds to the new basis with the largest norm. This algorithm runs very fast and can also avoid the dilemma in traditional simplex-based endmember extraction algorithms, such as N-FINDR, that it generally produces different sets of final endmembers if different initial conditions are used. Moreover, with this set of orthogonal bases, the proposed algorithm can also determine the proper number of endmembers and finish the unmixing of the original images which the traditional simplex-based algorithms cannot do by themselves. Experimental results of both artificial simulated images and practical remote sensing images demonstrate the algorithm proposed in this paper is a fast and accurate algorithm for the decomposition of mixed pixels.
基金financially supported by the Foundation of Shanxi Key Laboratory of Machine Vision and Virtual Reality (Grant No.447-110103)the Science and Technology Innovation Plan of Shanghai Science and Technology Commission (Grant No. 22dz1204000)。
文摘Maritime target recognition and image perception enhancement are gradually being promoted and applied in ocean engineering. This paper proposes the attentional multi-pixel fusion(AMF) algorithm for the intelligent navigation of unmanned surface vessels(USVs). The algorithm preprocesses the image pixel matrix in blocks, computes the mapping between regional and full-pixel matrices, and adaptively equalizes the mapping weights via a Gaussian-fuzzy matrix.This approach guarantees the preservation of the target contour and texture information. Compared with five classic enhancement algorithms, the AMF algorithm improves the peak signal-to-noise ratio(PSNR) and structural similarity index(SSIM). Experimental validation via YOLOv8 for maritime target detection demonstrates 2.1% and 2.4%improvements in the evaluation indices over training on 4000 original images, with shorter training times and lower confusion rates. In maritime target ranging, the AMF algorithm, coupled with the ISR method, exhibits the lowest improved stereo ranging mean absolute error and standard deviation values and higher similarity between the regional and full-pixel matrices. In summary, the AMF algorithm excels in target detection and ranging, offering promising applications in ocean engineering, such as marine resource exploitation, path planning, and intelligent collaboration among unmanned vessels.
文摘The surface velocity is one of the most important characteristics of glaciers.Monitoring and mapping glacier movements are of great significance for the studies of sea-level rise,glacier mass balance and dynamics,global warming,and the management of freshwater resources.It is also essential for the early warnings of hazards caused by ice avalanches.SAR imaging geodesy has been developed for measuring glacier velocity,especially the pixel-offset tracking method.This paper introduces some basic concepts of glaciology and principles of various SAR imaging geodesy methods,with a detailed presentation about the developments in the applications of the pixel-offset tracking method.Finally,the challenges and future prospects of SAR imaging geodesy in glacier monitoring are discussed.
基金supported by the National Natural Science Foundation of China(42372144)the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2024D01E09)the Strategic Cooperation Technology Projects of CNPC and CUPB(ZLZX2020-01-05).
文摘The types and structures of inorganic pores are key factors in evaluations of the reservoir space and distribution characteristics of shale oil and gas.However,quantitative identification methods for pores of different inorganic components have not yet been fully developed.For this reason,a quantitative characterization method of inorganic pores using pixel information was proposed in this study.A machine learning algorithm was used to assist the field emission scanning electron microscopy(FE-SEM)image processing of shale to realize the accurate identification and quantitative characterization of inorganic pores on the surface of high-precision images of shale with a small view.Moreover,large-view image splicing technology,combined with quantitative evaluation of minerals by scanning electron microscopy(QEMSCAN)image joint characterization technology,was used to accurately analyze the distribution characteristics of inorganic pores under different mineral components.The quantitative methods of pore characteristics of different inorganic components under the pixel information of shale were studied.The results showed that(1)the Waikato Environment for Knowledge Analysis(WEKA)machine learning model can effectively identify and extract shale mineral components and inorganic pore distribution,and the large-view FE-SEM images are representative of samples at the 200μm×200μm view scale,meeting statistical requirements and eliminating the influence of heterogeneity;(2)the pores developed by different mineral components of shale had obvious differences,indicating that the development of inorganic pores is highly correlated with the properties of shale minerals themselves;and(3)the pore-forming ability of different mineral components is calculated by the quantitative method of single component pore-forming coefficient.Chlorite showed the highest pore-forming ability,followed by(in descending order)illite,pyrite,calcite,dolomite,albite,orthoclase,quartz,and apatite.This study contributes to advancing our understanding of inorganic pore characteristics in shale.
基金financially supported by the Natural Science Foundation of China(42301492)the Open Fund of Hubei Key Laboratory of Intelligent Vision Based Monitoring for Hydroelectric Engineering(2022SDSJ04,2024SDSJ03)+1 种基金the Opening Fund of Key Laboratory of Geological Survey and Evaluation of Ministry of Education(GLAB 2023ZR01,GLAB2024ZR08)the Fundamental Research Funds for the Central Universities.
文摘Automatic segmentation and recognition of content and element information in color geological map are of great significance for researchers to analyze the distribution of mineral resources and predict disaster information.This article focuses on color planar raster geological map(geological maps include planar geological maps,columnar maps,and profiles).While existing deep learning approaches are often used to segment general images,their performance is limited due to complex elements,diverse regional features,and complicated backgrounds for color geological map in the domain of geoscience.To address the issue,a color geological map segmentation model is proposed that combines the Felz clustering algorithm and an improved SE-UNet deep learning network(named GeoMSeg).Firstly,a symmetrical encoder-decoder structure backbone network based on UNet is constructed,and the channel attention mechanism SENet has been incorporated to augment the network’s capacity for feature representation,enabling the model to purposefully extract map information.The SE-UNet network is employed for feature extraction from the geological map and obtain coarse segmentation results.Secondly,the Felz clustering algorithm is used for super pixel pre-segmentation of geological maps.The coarse segmentation results are refined and modified based on the super pixel pre-segmentation results to obtain the final segmentation results.This study applies GeoMSeg to the constructed dataset,and the experimental results show that the algorithm proposed in this paper has superior performance compared to other mainstream map segmentation models,with an accuracy of 91.89%and a MIoU of 71.91%.
基金the financial support provided by the National Key R&D Program of China(2022YFB3805700)the National Natural Science Foundation of China(Grant Nos.12072094 and 12172106)+2 种基金the China Postdoctoral Science Foundation(Grant No.2023M730869)the Heilongjiang Natural Science Foundation Joint Guidance Project(Grant No.LH2023A004)the Postdoctoral Fellowship Program of CPSF(Grant No.GZB20230959)。
文摘Metamaterials have exotic physical properties that rely on the construction of their underlying architecture.However,the physical properties of conventional mechanical metamaterials are permanently programmed into their periodic interconnect configurations,resulting in their lack of modularity,scalable fabrication,and programmability.Mechanical metamaterials typically exhibit a single extraordinary mechanical property or multiple extraordinary properties coupled together,making it difficult to realize multiple independent extraordinary mechanical properties.Here,the pixel mechanics metamaterials(PMMs)with multifunctional and reprogrammable properties are developed by arraying uncoupled constrained individual modular mechanics pixels(MPs).The MPs enable controlled conversion between two extraordinary mechanical properties(multistability and compression-torsion coupling deformation).Each MP exhibits 32 independent and reversible room temperature programming configurations.In addition,the programmability of metamaterials is further enhanced by shape memory polymer(SMP)and 4D printing,greatly enriching the design freedom.For the PMM consisting of m×n MPs,it has 32(m×n)independent room temperature programming configurations.The application prospects of metamaterials in the vibration isolation device and energy absorption device with programmable performance have been demonstrated.The vibration isolation frequencies of the MP before and after programming were[0 Hz-5.86 Hz],[0 Hz-13.67 Hz and 306.64 Hz-365.23 Hz].The total energy absorption of the developed PMM can be adjusted controllably in the range of 1.01 J-3.91 J.Six standard digital logic gates that do not require sustained external force are designed by controlling the closure between the modules.This design paradigm will facilitate the further development of multifunctional and reprogrammable metamaterials.
