- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Spectral analysis and temperature measurement during flash sintering under AC electric field
摘要： In-situ diffraction experiments were used to study the change in peak profiles of 8YSZ during conventional sintering and flash sintering under AC electric field. Using calibration from a conventionally heated standard, the lattice expansion of 8YSZ under flash conditions was correlated to actual specimen temperature, indicating temperature comparable to that required for conventional sintering. At higher current densities, a temperature rise greater than 2000 °C was reached, which resulted in abnormal grain growth and temperature instability. Microstructural analysis demonstrated that finer grain size can be achieved by limiting the current in order to avoid high specimen temperatures. Experiments varying the thickness of the green compact resulted in higher heat loss due to thermal conduction and corresponding reduction in final density. A replacement to the blackbody radiation model was successfully used to fit the data and explain all effects based on Joule heating as well as provide a flash sintering processing map incorporating furnace temperature, power dissipation, and sample geometry.
关键词： 8YSZ,processing map,fast firing,flash sintering,energy dispersive diffraction
更新于2025-11-21 11:01:37
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[IEEE 2017 4th International Conference on Opto-Electronics and Applied Optics (Optronix) - Kolkata (2017.11.2-2017.11.3)] 2017 4th International Conference on Opto-Electronics and Applied Optics (Optronix) - A noble approach to light the path trail using swarm technology
摘要： Swarm intelligence (Intro SI) is the collective behaviour of decentralized, self-organized systems, natural or artificial. It is many minds working together. It is the first step in allowing people to pool their knowledge and insights into a single elevated intelligence. The objective is to light on a path trail by the leading robot, so that the rest of the robots could follow the trail to work as a unified system, thereby reducing time and manpower.
关键词： adaptive path exploration,swarm intelligence,Robot sensing systems,cognitive map generation,neighbouring robots,path trail information
更新于2025-09-23 15:23:52
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Comparison of block-based stereo and semi-global algorithm and effects of pre-processing and imaging parameters on tree disparity map
摘要： One method of creating a 3D model of a tree is stereo vision technique. Tree geometric characteristics have been used to predict yield, fertilizer application in citrus crops, water consumption or biomass. So, a disparity map and 3D model of the tree can be useful. There are different algorithms to match the stereo pair for calculating disparity maps. Many parameters affect the disparity map, such as the lighting that affects camera and imaging parameters, the calibration that needed to rectify the image, etc. In this study, the block-based stereo and semi-global algorithms with 5 implementations were compared to calculate tree disparity maps. Also, the effects of ISO speed, exposure time, metering mode (imaging parameters) and image un-distortion and rectification (pre-processing) were investigated. The results showed that the semi-global algorithm was better than the block-based stereo algorithm. Windows size affected on disparity maps and best results obtained when this parameter was set to default. Maximum disparity value limits search space. Best results obtained in real value. For smaller value than real value, disparity map was not calculated outside that maximum disparity. Therefore, disparities or pixels missed. It observed that image rectifying, ISO speed, exposure time and metering mode were affected on disparity map. When pictures did not rectify, disparity map calculated but with some errors. Camera parameters were affected on light intensity of pictures. Best disparity map obtained in conditions that ISO speed and exposure time had fewer value and metering mode was set to pattern mode and these parameters were similar for both left and right images.
关键词： ISO speed,Exposure time,Rectify,Disparity map,Semi-global matching,Tree
更新于2025-09-23 15:23:52
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[IEEE 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV) - Singapore, Singapore (2018.11.18-2018.11.21)] 2018 15th International Conference on Control, Automation, Robotics and Vision (ICARCV) - Map Comparison of Lidar-based 2D SLAM Algorithms Using Precise Ground Truth
摘要： This paper presents a comparative analysis of three most common ROS-based 2D Simultaneous Localization and Mapping (SLAM) libraries: Google Cartographer, Gmapping and Hector SLAM, using a metric of average distance to the nearest neighbor (ADNN). Each library was applied to construct a map using data from 2D lidar that was placed on an autonomous mobile robot. All the approaches have been evaluated and compared in terms of inaccuracy constructed maps against the precise ground truth presented by FARO laser tracker in static indoor environment.
关键词： ground truth,ADNN,lidar,ROS,map comparison,SLAM
更新于2025-09-23 15:23:52
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[IEEE 2018 24th International Conference on Pattern Recognition (ICPR) - Beijing, China (2018.8.20-2018.8.24)] 2018 24th International Conference on Pattern Recognition (ICPR) - Accurate 3-D Reconstruction with RGB-D Cameras using Depth Map Fusion and Pose Refinement
摘要： Depth map fusion is an essential part in both stereo and RGB-D based 3-D reconstruction pipelines. Whether produced with a passive stereo reconstruction or using an active depth sensor, such as Microsoft Kinect, the depth maps have noise and may have poor initial registration. In this paper, we introduce a method which is capable of handling outliers, and especially, even significant registration errors. The proposed method first fuses a sequence of depth maps into a single non-redundant point cloud so that the redundant points are merged together by giving more weight to more certain measurements. Then, the original depth maps are re-registered to the fused point cloud to refine the original camera extrinsic parameters. The fusion is then performed again with the refined extrinsic parameters. This procedure is repeated until the result is satisfying or no significant changes happen between iterations. The method is robust to outliers and erroneous depth measurements as well as even significant depth map registration errors due to inaccurate initial camera poses.
关键词： point cloud,3-D reconstruction,RGB-D cameras,pose refinement,depth map fusion,registration errors
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Information and Communication Technology Robotics (ICT-ROBOT) - Busan, Korea (South) (2018.9.6-2018.9.8)] 2018 International Conference on Information and Communication Technology Robotics (ICT-ROBOT) - Global Map Generation using LiDAR and Stereo Camera for Initial Positioning of Mobile Robot
摘要： A lot of researches have been made on how to know the position of the mobile robot when it knows the initial position of the mobile robot. For the robot to be completely unmanned, the robot also needs to find out its own initial position. To do this, it is necessary to obtain enough data to estimate the initial position without previous data. In Simultaneous Localization and Mapping (SLAM), Light Detection and Ranging (LiDAR) is often used to obtain accurate map for mobile robot. In this case, it is difficult to find the initial position because there is little information at initial start-up. On the other hand, stereo camera has the advantage that it can acquire more information than LiDAR by acquiring spatial information with the same principle as the human eye. However, the obtained 3D spatial information has a disadvantage of low precision. The purpose of this paper is to form a 3D map to be used for finding the initial position by linking LRF information to compensate for the low accuracy of the 3D map made only by the stereo camera in the environment.
关键词： 3D Map,Stereo Camera,LiDAR,Initial Positioning,SLAM
更新于2025-09-23 15:23:52
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Bonding of Large Substrates by Silver Sintering and Characterization of the Interface Thermal Resistance
摘要： Low-temperature silver sintering technology, which has been proven to be a promising die-attach solution, was extended to bonding large substrates. Strong bonding strengths for substrates greater than 25 mm × 50 mm were achieved by sintering a nanosilver paste at temperatures below 270oC with less than 5 MPa pressure. To characterize the thermal performance of the substrate-attach interface, we applied a transient thermal technique with cumulative structure function analysis. Using self-heating and temperature-sensitive threshold voltage of a power device, we measured the transient thermal responses of the device placed at various locations on the bonded structures. Each transient thermal response was used to determine cumulative structure function, which represents the relationship between cumulative thermal capacitance and cumulative thermal resistance from the device junction to the ambient environment. Two-dimensional maps corresponding to interface thermal resistance were obtained from structure function plots. We found that for well-bonded substrates, the average specific thermal resistance contributed by the sintered silver interface was between 5.20 mm2K/W and 5.78 mm2K/W with a variation of 4.7% to 6.0%.
关键词： silver sintering,Substrate-attach,two-dimensional map of interface thermal resistance,transient thermal characterization
更新于2025-09-23 15:23:52
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A cryogenic cylindrical ion trap velocity map imaging spectrometer
摘要： A cryogenic cylindrical ion trap velocity map imaging spectrometer has been developed to study photodissociation spectroscopy and dynamics of gaseous molecular ions and ionic complexes. A cylindrical ion trap made of oxygen-free copper is cryogenically cooled down to ～7 K by using a closed cycle helium refrigerator and is coupled to a velocity map imaging (VMI) spectrometer. The cold trap is used to cool down the internal temperature of mass selected ions and to reduce the velocity spread of ions after extraction from the trap. For CO2+ ions, a rotational temperature of ～12 K is estimated from the recorded [1 + 1] two-photon dissociation spectrum, and populations in spin-orbit excited X2Πg,1/2 and vibrationally excited states of CO2+ are found to be non-detectable, indicating an efficient internal cooling of the trapped ions. Based on the time-of-flight peak profile and the image of N3+ ions, the velocity spread of the ions extracted from the trap, both radially and axially, is interpreted as approximately ±25 m/s. An experimental image of fragmented Ar+ from 307 nm photodissociation of Ar2+ shows that, benefiting from the well-confined velocity spread of the cold Ar2+ ions, a VMI resolution of Δv/v ～ 2.2% has been obtained. The current instrument resolution is mainly limited by the residual radial speed spread of the parent ions after extraction from the trap.
关键词： cryogenic ion trap,velocity map imaging,ion cooling,photodissociation,spectroscopy
更新于2025-09-23 15:23:52
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Retrieval of Ionospheric Faraday Rotation Angle in Low-frequency Polarimetric SAR Data
摘要： A low-frequency spaceborne synthetic aperture radar (SAR) working system, e.g., operating at the L-band or P-band, has great advantages of military target detection and biomass monitoring. Nevertheless, it is more susceptible to ionospheric effects compared with the higher frequency system. A trans-ionospheric wave propagation model is established in this paper to incorporate ionospheric effects on SAR signals. As one of the signi?cant distortion sources for the polarimetric SAR (PolSAR), Faraday rotation (FR) is mainly imposed by background ionosphere, and its spatial variation is discussed. FR estimators have been devised in succession to estimate FR angle (FRA), and various potential novel estimators can still be derived. But, from a viewpoint of theoretical expressions, the earliest estimator is bound to be the optimal one. Based on PolSAR real data, this mathematical conclusion is further validated via comprehensive performance analysis as to estimation bias and standard deviation rather than the existent root-mean-square principle. Finally, a step-by-step procedure of the FRA map is proposed and operated with an application of the airborne P-band PolSAR data. In particular, the ambiguity error of FRA estimates within a SAR observation is simulated and resolved. By processing the ALOS-2 real data, the spatial distribution of FRAs is retrieved and used to operate ionospheric total electron content soundings.
关键词： FR angle (FRA) map,ionospheric TEC soundings,Faraday rotation (FR) estimators,Spaceborne synthetic aperture radar (SAR)
更新于2025-09-23 15:23:52
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[ACM Press SIGGRAPH Asia 2018 Posters - Tokyo, Japan (2018.12.04-2018.12.07)] SIGGRAPH Asia 2018 Posters on - SA '18 - Panoramic depth reconstruction within a single shot by optimizing global sphere radii
摘要： Depth estimation in scene reconstruction remains one of the main issues in the world of virtual reality. We propose a method that uses low cost camera facilities from previous papers and their specified procedures for stereoscopic 360 imaging. However, instead of using angular disparity, we use the spherical radius for labeling depth values for scene reconstruction. The experimental results show that the reconstructed shape is less distorted by directly optimizing spherical radii than optimizing the angular disparities.
关键词： Matching cost map,Polycamera,Inverse radius disparity depth estimation,Depth Reconstruction,Depth map
更新于2025-09-23 15:22:29