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Increase of the particle hit rate in a laser single-particle mass spectrometer by pulse delayed extraction technology
摘要： A single-particle mass spectrometer (SPMS) can provide a wealth of valuable information on chemical and physical parameters of individual particles in real time. One of the main performance criteria of the instrument is efficiency of particle detection (hit rate). Most SPMS instruments use constant electrical field (DC) extraction, where stationary high voltage is applied to the extraction electrodes. As the aerosol particles initially carry a certain charge, those with a high amount to charge can be deflected by this electric field and lost, thus decreasing the hit rate. We realized that the delayed extraction technique can eliminate the stochastic dispersion of the particle beam caused by their deflection in the stationary electric field. As the result, the hit rate of the instrument can be significantly improved. Also, as the effect of the deflection in the electric field is mass dependent, it can cause distortion of the measured size distribution of the particles. Hence, the delayed extraction technique can bring the recorded distribution closer to the actual one. We found that the delayed extraction technique provides a mass resolution improvement as well as increases the hit rate. The gain in the hit rate depends on the type of particles. It can be 2 orders of magnitude for model particles and up to 2–4 times for ambient particles. In the present work we report experiments and results showing the effect of the delayed extraction on the beam divergence caused by particle charge, the hit rate improvement, and the effect of the delayed extraction on the measured particle size distribution.
关键词： hit rate,particle charge,aerosol particles,delayed extraction,single-particle mass spectrometer
更新于2025-09-23 15:19:57
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Improved auto-extrinsic calibration between stereo vision camera and laser range finder
摘要： This study identifies a way to accurately estimate extrinsic calibration parameters between stereo vision camera and 2D laser range finder (LRF) based on 3D reconstruction of monochromatic calibration board and geometric co-planarity constraints between the views from these two sensors. It supports automatic extraction of plane-line correspondences between camera and LRF using monochromatic board, which is further improved by selecting optimal threshold values for laser scan dissection to extract line features from LRF data. Calibration parameters are then obtained by solving co-planarity constraints between the estimated plane and line. Furthermore, the obtained parameters are refined by minimising reprojection error and error from the co-planarity constraints. Moreover, calibration accuracy is achieved because of extraction of reliable plane-line correspondence using monochromatic board which reduces the impact of range-reflectivity-bias observed in LRF data on checkerboard. As the proposed method supports to automatically extract feature correspondences, it provides a major reduction in time required from an operator in comparison to manual methods. The performance is validated by extensive experimentation and simulation, and estimated parameters from the proposed method demonstrate better accuracy than conventional methods.
关键词： plane-line correspondences,laser-camera calibration,Range-reflectivity-bias,automatic feature extraction
更新于2025-09-23 15:19:57
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[IEEE 2019 International Conference on Electrical, Electronics and Computer Engineering (UPCON) - ALIGARH, India (2019.11.8-2019.11.10)] 2019 International Conference on Electrical, Electronics and Computer Engineering (UPCON) - Performance Optimization of p-n Junction Solar cells with Device Architecture
摘要： Huynen decomposition (HD) as the first formalized target decomposition has not been widely accepted. The preference for symmetry and regularity restricts not only its application but also its unification with other target dichotomies. The nonuniqueness issue then arises because we may have different dichotomies of radar targets, but we have no idea on how to select them. In this paper, a unified Huynen dichotomy is developed by extending HD for a full preference for symmetry and regularity, nonsymmetry, irregularity, and their couplings. It covers all of the existing dichotomies and provides a unified selection mechanism for them. Scattering preference is identified as a main feature of target dichotomy, and its concise description is devised by relating each dichotomy to a canonical scattering. A scattering degree of preference (SDoP) parameter is defined to measure the preference of each dichotomy. In virtue of an adaptive combination and permutation of SDoPs, a scattering pyramid description of the mixed scattering is developed, which has better discrimination of target than entropy/alpha. An SDoP/alpha classification is further proposed by statistical modeling of the unified dichotomy, which is a competent alternative to entropy/alpha. The excellent performance of unified dichotomy makes us believe that the existing concerns on HD are well treated and the Huynen–Cloude controversy, in a sense, may be ended.
关键词： target decomposition,Huynen decomposition (HD),unsupervised classification,target extraction,radar polarimetry
更新于2025-09-23 15:19:57
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Some analyses on optimal energy-extraction efficiency in a free-electron laser
摘要： In this paper, the energy-extraction efficiencies of the electron beam are studied for several cases of free-electron laser (FEL). For an initially cold electron beam, the optimal initial detuning for the maximum energy-extraction efficiency and the corresponding saturation length are given. A scheme of the ‘top up’ is proposed to enhance the efficiency: after the electron energy being modulated somewhat, a phase shift and a step-down of the phase bucket are introduced, so that all electrons are located near the upper separatrix of the bucket in the phase space. Finally, the energy-extraction efficiency can be increased by 30% compared with that of the normal undulator case. For a linear tapering undulator with an initially cold electron beam, the simple scaling laws for the maximum energy-extraction efficiency and the corresponding optical power gain are obtained. For a tapered undulator with the pre-bunched electron beam, our analysis gives that the energy-extraction efficiency reaches the maximum when the phase bucket height of the tapered undulator is equal to the amplitude of the detuning modulation. The numerical results validated this reasoning and show that the efficiency has a large increase compared with the case of the unbunched electron beam. The single stair-step undulator is investigated, the optimal step and the corresponding saturation power and saturation length are given by analysis, they agree well with the numerical simulation results.
关键词： pre-bunched,tapered undulator,free-electron laser,energy-extraction efficiency
更新于2025-09-23 15:19:57
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[IEEE 2019 Chinese Control Conference (CCC) - Guangzhou, China (2019.7.27-2019.7.30)] 2019 Chinese Control Conference (CCC) - A Novel Multi-Objective optimization Model for Integrated Photovoltaic/Hydroelectric Power Generation Operation
摘要： A very-large-scale integration capable of extracting motion features from moving images in real time has been developed employing row-parallel and pixel-parallel architectures based on the digital pixel sensor technology. Directional edge filtering of input images is carried out in row-parallel processing to minimize the chip real estate. To achieve a real-time response of the system, a fully pixel-parallel architecture has been explored in adaptive binarization of filtered images for essential feature extraction as well as in their temporal integration and derivative operations. As a result, self-speed-adaptive motion feature extraction has been established. The chip was designed and fabricated in a 65-nm CMOS technology and used to build an object detection system. Motion-sensitive target image localization was demonstrated as an illustrative example.
关键词： parallel architecture,digital pixel sensor (DPS),Block-readout scheme,motion feature extraction (MFE),vision chip
更新于2025-09-23 15:19:57
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Interface Defects Passivation and Conductivity Improvement in Planar Perovskite Solar Cells Using Na2S Doped Compact-TiO2 Electron Transport Layers
摘要： Numerous trap states and low conductivity of compact TiO2 layers are major obstacles for achieving high power conversion efficiency and high stability perovskite solar cells. Here we report an effective Na2S doped TiO2 layer, which can improve the conductivity of TiO2 layers, the contact of TiO2/perovskite interface, and also the crystallinity of following perovskite layers. Comprehensive investigations demonstrate that Na cations would increase the conductivity of TiO2 layers while S anions would change the wettability of TiO2 layers, and improve the crystallinity of perovskite layers and passivate defects at the TiO2/PVK interface. Synergetic effects of dopants lead to a champion efficiency as high as 21.25% in unencapsulated PSCs, with much improved stability. Our work provides new insights on anion dopants in TiO2 layers which is usually neglected in previous reports, and also proposes a simple approach to produce low-cost and high-performance electron transporting layers for high performance PSCs.
关键词： electron extraction,additive,compact TiO2,perovskite solar cells,crystallization
更新于2025-09-23 15:19:57
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The Effects of Diabetic Retinopathy Stage and Light Flicker on Inner Retinal Oxygen Extraction Fraction
摘要： PURPOSE. We determined the effects of light ?icker and diabetic retinopathy (DR) stage on retinal vascular diameter (D), oxygen saturation (SO2), and inner retinal oxygen extraction fraction (OEF). METHODS. Subjects were categorized as nondiabetic control (NC, n ? 42), diabetic with no clinical DR (NDR; n ? 32), nonproliferative DR (NPDR; n ? 42), or proliferative DR (PDR; n ? 14). Our customized optical imaging system simultaneously measured arterial and venous D (DA, DV) and SO2 (SO2A, SO2V) before and during light ?icker. Inner retinal OEF was derived from SO2 values. Light ?icker–induced ratios of metrics (DAR, DVR, SO2AR, SO2VR, OEFR) were calculated. RESULTS. Arterial D was larger in NPDR compared to NC (P ? 0.01) and PDR (P ? 0.002), whereas DV was similar among groups (P ? 0.16). Light ?icker increased DA and DV (P (cid:2) 0.004), but DAR and DVR were similar among groups (P ? 0.09). Arterial SO2 was higher in all groups compared to NC (P (cid:2) 0.02) and higher in PDR compared to NDR and NPDR (P<0.001). Arterial SO2 did not change with light ?icker (P ? 0.1). Venous SO2 was higher in NPDR and PDR compared to NC and NDR (P (cid:2) 0.02). Light ?icker increased SO2V in NC, NDR, and PDR (P (cid:2) 0.003), and SO2VR was lower in NPDR compared to NC and NDR (P (cid:2) 0.05). Inner retinal OEF was lower in NPDR compared to NDR and PDR (P (cid:2) 0.02). Light ?icker decreased OEF (P (cid:2) 0.03), but OEFR was greater in NPDR compared to NC and NDR (P (cid:2) 0.03). CONCLUSIONS. The ?ndings of alterations in retinal D, SO2, OEF, and their light ?icker–induced responses at stages of DR may be useful to elucidate the pathophysiology of DR.
关键词： light ?icker stimulation,inner retinal oxygen extraction fraction,diabetic retinopathy,retina
更新于2025-09-23 15:19:57
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European Microscopy Congress 2016: Proceedings || Indexation of diffraction patterns for overlapping crystals in TEM thin foils - Application to orientation mappings
摘要： Application of diffraction gratings for overcoming limitations in organic light-emitting diodes (OLEDs) for displays. The study focuses on enhancing light extraction efficiency and managing color shifts in OLEDs using a novel grating design. The experimental approach involves fabricating and characterizing grating structures on OLED substrates, with results showing significant improvements in efficiency and color stability compared to conventional methods.
关键词： diffraction gratings,color shift,efficiency,OLEDs,light extraction
更新于2025-09-19 17:15:36
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Robust Visual Tracking Based on Adaptive Extraction and Enhancement of Correlation Filter
摘要： In recent years, correlation filter (CF)-based tracking methods have demonstrated competitive performance. However, conventional CF-based methods suffer from unwanted boundary effects because of the periodic assumption of the training and detection samples. A spatially regularized discriminative CF (SRDCF) has greatly alleviated boundary effects by proposing the spatial regularization weights, which penalize the CF coefficients during learning. However, the SRDCF utilizes a naive decaying exponential model to passively and fixedly update the CF from the previous results. Therefore, if the target meets with occlusion or is out of view, the SRDCF may encounter over-fitting to the recent polluted samples, which may lead to tracking drift and failure. In this paper, we present a novel CF-based tracking method to resolve this issue by dynamically and adaptively correcting the weights of learning CFs and fusing them together to promote a more robust tracking. Thus, if the recent samples are inaccurate in the case of occlusion or are out of view, our method will down-weight the corresponding CFs and vice versa. Moreover, in order to decrease computational complexity and ensure memory efficiency, we extract the key CFs from the previous frames to remove redundant CFs under the contiguous frame indexes constraint. Thus, we do not need to store all CFs and decrease computational burden. Benefiting from the extraction and enhancement of CF, our method improves the tracking precision on OTB-2015, VOT-2016 and UAV123 benchmarks and achieves a 56.0% relative gain in speed compared with the SRDCF. The extensive experimental results demonstrate that our method is competitive with the state-of-the-art algorithms.
关键词： sample learning,adaptive extraction and enhancement,Visual tracking,correlation filter
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE/ACS 15th International Conference on Computer Systems and Applications (AICCSA) - Aqaba, Jordan (2018.10.28-2018.11.1)] 2018 IEEE/ACS 15th International Conference on Computer Systems and Applications (AICCSA) - Number of Texture Unit as Feature to Breast's Disease Classification from Thermal Images
摘要： This paper presents the use of the Number of Texture Unit as a feature extractor for classification of breast images. The Number of Texture Unit served as the basis for the idealization of the Local Binary Pattern a technique that is widely used in facial recognition. We compared the proposed strategy with the Gray Level Co-occurrence Matrix which is the most used texture analysis technique in the literature. With this work we have been able to show that the combination of the two techniques of feature extraction improves the final result of classification. To perform the tests we used the Support Vectors Machine classifier and obtained a result of 96.15% Area Under the Curve (Receiver Operating Characteristic Curve).
关键词： computer aided diagnosis,machine learning,support vector machine,feature extraction,infrared images,Local Binary Pattern
更新于2025-09-19 17:15:36