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- 2018
- railway track
- kinematic characteristics
- stereo vision
- image blur
- distance estimation
- control system
- depth of field
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- Chongqing University of Posts and Telecommunications
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Advanced Coating Materials || Effects of Laser Process Parameters on Overlapped Multipass/Multitrack Hardened Bead Parameters of Ti-6Al-4V Titanium Alloy Using Continuous-Wave Rectangular Beam
摘要： Commercially pure titanium and titanium alloy Ti-6Al-4V are essentially utilized in aerospace industry for the airframes and the aircraft engine parts, such as gas turbine and turbo fan blades, respectively. Since titanium alloys Ti-6Al-4V are stronger than commercially pure titanium, they are employed in aerospace applications for their light weight, high strength (high specific strength), and heat resistance properties. In this research work, overlapped multitrack laser transformation hardening (OMLTH) of Ti-6Al-4V titanium alloy of Grade 5 of 2-mm thickness sheet has been carried out using 2-kW Nd:YAG laser source with a CW rectangular beam of size 1 × 14 mm2. The present research article intended to provide a profound understanding of the multipass laser hardening process of TI-6Al-4V titanium alloy, and to investigate the effect of rectangular laser beam process parameters, that is, the laser power, the scanning speed has been evaluated by means of experimental bead on trials. The overlapped multipass laser transformation hardening experiments were conducted using rectangular beam for the two selected process parameters: 1. low laser process parameter (LLPP), LP = 600 Watts, SS = 600 mm/min, and 2. high laser process parameter (HLPP), LP = 800 Watts, SS = 800 mm/min. The minimum hardened depth of 63.6364 microns was observed for low laser process parameter. The results indicate that the hardened depth increases with increase in power density. The maximum hardened depth of 278.7879 microns was achieved for high laser process parameter with high power density. It has been seen that the depth of hardening increases with increase in laser interaction time with the material.
关键词： Ti-6Al-4V,rectangular laser beam,laser transformation hardening,hardened depth,multitrack,Overlapped
更新于2025-09-19 17:15:36
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[IEEE 2018 Digital Image Computing: Techniques and Applications (DICTA) - Canberra, Australia (2018.12.10-2018.12.13)] 2018 Digital Image Computing: Techniques and Applications (DICTA) - Fast and Energy-Efficient Time-of-Flight Distance Sensing Method for 3D Object Tracking
摘要： We present a new energy-ef?cient distance sensing method for 3D object tracking with Time-of-Flight sensors. The ?eld of 3D object tracking with 3D cameras recently gained momentum due to the advent of front-facing depth cameras in smartphones. Tracking the user’s head with 3D cameras will enable novel user experiences, but can lead to power consumption issues due to the active illumination. State-of-the-art continuous-wave Time-of-Flight imaging requires at least four different phase-images, while our approach can produce 3D measurements from single phase-images. This reduces the amount of emitted light to a minimum, improves latency and enables higher framerates. As our evaluation shows, after a brief initialization phase, our method can reduce the power consumption of a Time-of-Flight system by up to 68%.
关键词： Time-of-Flight,3d object tracking,face tracking,depth sensing,phase-images,smartphones
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Singapore (2018.7.16-2018.7.19)] 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Improved Phase Data Acquisition for Thermal Emissions Analysis
摘要： This paper describes a 2X improvement in phase data acquisition for Lock-in Thermography (LIT). Phase data is used to generate phase shift versus applied lock-in frequency plots to estimate defect depth in semiconductor packages. Typically, samples need to be tested for an extended time to ensure data consistency. Furthermore, determining the specific point on the thermal emission site to collect data from can be challenging, especially if it is large and dispersive. To overcome these difficulties, new computational algorithms along with streamlined and automated workflows, such as self-adjusting site positioning and phase measurement auto-stop, are employed to validate improvements to data repeatability and accuracy as well as faster time to results on different advanced packaging devices such as flip chips and stack dies. Overall, our results showed a 2X faster time to more accurate and repeatable data for X, Y, and Z depth localization.
关键词： Z depth localization,Lock-in thermography
更新于2025-09-19 17:15:36
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Effective orthoscopic integral imaging reconstruction via adjustable depth position
摘要： In this paper, we propose an effective orthoscopic three-dimensional reconstruction via adjustable depth position in integral imaging system. Compared to conventional integral imaging reconstruction method, the proposed method can directly reconstruct orthoscopic 3D images through one-step ray tracing with adjustable depth positions. Thus, a real, undistorted, orthoscopic three-dimensional images can be reconstructed various distances without the magnification and overlap process of conventional integral imaging reconstruction. To show the feasibility of the proposed method, the preliminary experiments are carried out and the some experimental results are presented.
关键词： Adjustable depth position,Orthoscopic integral imaging reconstruction,Integral imaging
更新于2025-09-19 17:15:36
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Measurement of Electron Mobility-Lifetime Product in 3-D Position-Sensitive CdZnTe Detectors Using the VAD_UMv2.2 Digital Readout System
摘要： The electron mobility-lifetime product, μeτe, was calculated for 3-D position-sensitive CdZnTe detectors using the two-bias and depth-fitting methods. The anode and cathode signals were digitally sampled from preamplifiers and read out using the VAD_UM v2.2 electronic readout system. With conventional digital filters, the measured μeτe values by depth-fitting were about 30% higher than the two-bias method. By analyzing the averaged waveforms, the effects of electron drift and detrapping were found to cause a significant underestimate of μeτe. With an optimized filtering method (simple subtraction method), the measured μeτe values calculated using different methods at different biases were consistent. The μeτe values were also significantly higher than the results from conventional waveform filtering methods. Repeated measurements showed relative uncertainties of 20% for the μeτe values. Increased μeτe values were observed for CdZnTe detectors delivered by Redlen Technologies over the past several years. The μeτe values from the latest large volume pixelated CdZnTe detectors were about 0.05 cm2/ V.
关键词： two-bias method,CdZnTe detectors,μeτe,digital readout,depth-fitting method
更新于2025-09-19 17:15:36
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Accurate depth estimation of skin surface using a light-field camera toward dynamic haptic palpation
摘要： Background: Haptic skin palpation with three-dimensional skin surface reconstruction from in vivo skin images in order to acquire both tactile and visual information has been receiving much attention. However, the depth estimation of skin surface, using a light field camera that creates multiple images with a micro-lens array, is a difficult problem due to low-resolution images resulting in erroneous disparity matching. Methods: Multiple low-resolution images decoded from a light field camera have limitations to accurate 3D surface reconstruction needed for haptic palpation. To overcome this, a deep learning method, Generative Adversarial Networks, was employed to generate super-resolved skin images that preserve surface detail without blurring, and then, accurate skin depth was estimated by taking multiple subsequent steps including lens distortion correction, sub-pixel shifted image generation using phase shift theorem, cost-volume building, multi-label optimization, and hole filling and refinement, which is a new approach for 3D skin surface reconstruction. Results: Experimental results of the deep-learning-based super-resolution method demonstrated that the textural detail (wrinkles) of super-resolved skin images is well preserved, unlike other super-resolution methods. In addition, the depth maps computed with our proposed algorithm verify that our method can produce more accurate and robust results compared to other state-of-the-art depth map computation methods. Conclusion: Herein, we first proposed depth map estimation of skin surfaces using a light field camera and subsequently tested it with several skin images. The experimental results established the superiority of the proposed scheme.
关键词： depth estimation,skin imaging,disparity estimation,dermatology,light field camera,haptic palpation
更新于2025-09-19 17:15:36
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Study of expanded austenite formed in plasma nitrided AISI 316L samples, using synchrotron radiation diffraction
摘要： AISI 316L stainless steel samples nitrided at different conditions of temperature and time, showing different properties, such as nitrogen concentration (CN) and nitrided layer thickness, were studied. Expanded austenite (gN) diffraction peaks up to the (222) reflection were observed using suitable wavelength synchrotron radiation. XRD patterns were fitted by Le Bail method, using a special triclinic crystal structure (with a lattice distortion η) for gN, whose peaks were decomposed in a few subpeaks, to consider CN gradient across the nitrided layer. Our results indicate that regarding gN magnetic behavior, which was observed for the samples nitrided at 450 °C, it seems to be correlated not only to high CN (≥31at.%), but also to higher η (≥2.4°), which reaches up to 5.6°. This distortion η decreases when CN increases, consequently, with its minimum close to the surface. On the other hand, for paramagnetic samples (350 °C), η increases up to 1.4° when CN increases up to 30 at.%.
关键词： magnetic character,layer depth,AISI 316L stainless steel,expanded austenite,synchrotron diffraction,plasma nitriding
更新于2025-09-19 17:15:36
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Retrieval of the Fine-Mode Aerosol Optical Depth over East China Using a Grouped Residual Error Sorting (GRES) Method from Multi-Angle and Polarized Satellite Data
摘要： The ?ne-mode aerosol optical depth (AODf) is an important parameter for the environment and climate change study, which mainly represents the anthropogenic aerosols component. The Polarization and Anisotropy of Re?ectances for Atmospheric Science coupled with Observations from a Lidar (PARASOL) instrument can detect polarized signal from multi-angle observation and the polarized signal mainly comes from the radiation contribution of the ?ne-mode aerosols, which provides an opportunity to obtain AODf directly. However, the currently operational algorithm of Laboratoire d’Optique Atmosphérique (LOA) has a poor AODf retrieval accuracy over East China on high aerosol loading days. This study focused on solving this issue and proposed a grouped residual error sorting (GRES) method to determine the optimal aerosol model in AODf retrieval using the traditional look-up table (LUT) approach and then the AODf retrieval accuracy over East China was improved. The comparisons between the GRES retrieved and the Aerosol Robotic Network (AERONET) ground-based AODf at Beijing, Xianghe, Taihu and Hong_Kong_PolyU sites produced high correlation coef?cients (r) of 0.900, 0.933, 0.957 and 0.968, respectively. The comparisons of the GRES retrieved AODf and PARASOL AODf product with those of the AERONET observations produced a mean absolute error (MAE) of 0.054 versus 0.104 on high aerosol loading days (AERONET mean AODf at 865 nm = 0.283). An application using the GRES method for total AOD (AODt) retrieval also showed a good expandability for multi-angle aerosol retrieval of this method.
关键词： multi-angular remote sensing,?ne-mode aerosol optical depth,optimal aerosol model determination,PARASOL,polarized remote sensing
更新于2025-09-19 17:15:36
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3D cellular imaging in thick biological tissue with confocal detection of one-photon fluorescence in the NIR-II window
摘要： Fluorescence imaging in the second near-infrared optical window (NIR-II, 900-1700 nm) has become a technique of choice for non-invasive in vivo imaging in recent years. Greater penetration depths with high spatial resolution and low background can be achieved with this NIR-II window, owing to low autofluorescence within this optical range and reduced scattering of long wavelength photons. Here, we present a novel design of confocal laser scanning microscope tailored for imaging in the NIR-II window. We showcase the outstanding penetration depth of our confocal setup with a series of imaging experiments. HeLa cells labeled with PbS quantum dots (QDs) with a peak emission wavelength of 1276nm can be visualized through a 3.5-mm-thick layer of scattering medium, which is a 0.8% Lipofundin solution. A commercially available organic dye IR-1061 (emission peak at 1132nm), in its native form, is used for the first time, as a NIR-II fluorescence label in cellular imaging. Our confocal setup is capable of capturing optically sectioned images of IR-1061 labeled chondrocytes in fixed animal cartilage at a depth up to 800μm, with a superb spatial resolution of around 2 μm.
关键词： scattering,NIR-II,resolution,penetration depth,confocal
更新于2025-09-19 17:15:36
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Impacts of distribution patterns of cloud optical depth on the calculation of radiative forcing
摘要： The gridding process applied to satellite-retrieved cloud properties results in the loss of certain information. In this study, we analyzed the error associated with using gridded cloud optical depth (τ) in calculating radiative forcing from the perspective of the distribution pattern of τ. Utilizing the simulated results from SBDART (Santa Babara DISORT Atmospheric Radiative Transfer), we calculated this error in ideal probability distribution functions (PDFs) of τ while keeping the average τ constant, and then used the τ retrieved from MODIS (Moderate Resolution Imaging Spectroradiometer) pixel-level observations to simulate real case studies. The results from both the ideal experiments and real case studies indicate that there is a large dependence of the error caused by gridding process on the PDF of τ. The greatest relative error occurs in the cases when τ fits a two-point or uniform distribution, reaching 10–20%, while this error is below 5% when τ follows a binomial distribution. From the analysis of MODIS pixel-level data from June 2016, we found that the PDFs of τ within one grid point (1° × 1°) could not be simply described by a normal distribution. Although using the logarithmic mean of τ controls the error effectively, the error can still be up to 4%. Our study suggests that using gridded data (especially the arithmetic mean) to calculate radiative forcing may result in uncertainty to a certain extent, which depends strongly on the distribution pattern of cloud properties within the grid point. The PDF of cloud properties should be comprehensively considered in the gridding process in the future.
关键词： Radiative forcing,Distribution pattern,Cloud optical depth,Grid,MODIS
更新于2025-09-19 17:15:36