1,564 research outputs found
Fusion of China ZY-1 02D Hyperspectral Data and Multispectral Data: Which Methods Should Be Used?
No full textZY-1 02D is China’s first civil hyperspectral (HS) operational satellite, developed independently and successfully launched in 2019. It can collect HS data with a spatial resolution of 30 m, 166 spectral bands, a spectral range of 400~2500 nm, and a swath width of 60 km. Its competitive advantages over other on-orbit or planned satellites are its high spectral resolution and large swath width. Unfortunately, the relatively low spatial resolution may limit its applications. As a result, fusing ZY-1 02D HS data with high-spatial-resolution multispectral (MS) data is required to improve spatial resolution while maintaining spectral fidelity. This paper conducted a comprehensive evaluation study on the fusion of ZY-1 02D HS data with ZY-1 02D MS data (10-m spatial resolution), based on visual interpretation and quantitative metrics. Datasets from Hebei, China, were used in this experiment, and the performances of six common data fusion methods, namely Gram-Schmidt (GS), High Pass Filter (HPF), Nearest-Neighbor Diffusion (NND), Modified Intensity-Hue-Saturation (IHS), Wavelet Transform (Wavelet), and Color Normalized Sharping (Brovey), were compared. The experimental results show that: (1) HPF and GS methods are better suited for the fusion of ZY-1 02D HS Data and MS Data, (2) IHS and Brovey methods can well improve the spatial resolution of ZY-1 02D HS data but introduce spectral distortion, and (3) Wavelet and NND results have high spectral fidelity but poor spatial detail representation. The findings of this study could serve as a good reference for the practical application of ZY-1 02D HS data fusion
Cone-beam computed tomography study of the root and canal morphology of mandibular permanent anterior teeth in a Chongqing population [Corrigendum]
No full textZhengyan Yang, Keke Lu, Fei Wang, Yueheng Li, Zhi ZhouDepartment of Preventive Dentistry, The College of Stomatology, The Affiliated Hospital of Stomatology, Chongqing Medical University, Chongqing, People’s Republic of ChinaOn page 19, the author’s names were listed incorrectly as Yang Zhengyan, Lu Keke, Wang Fei, Li Yueheng, Zhou Zhi.The correct names are Zhengyan Yang, Keke Lu, Fei Wang, Yueheng Li, Zhi Zhou.View the original paper here
Monitoring of Arsenic Exposure with Speciated Urinary Inorganic Arsenic Metabolites for Ion Implanter Maintenance Engineers
No full textHigh-performance Fe3O4-terephthalaldehyde magnetic-nanocomposite for removal phenanthrene and 9-phenanthrol: A comprehensive experimental and theoretical analysis
No full textAscribing to the serious environmental and health risks caused by phenanthrene (PENE) and its dangerous degradation intermediate, 9-phenanthrol (9-PENE), solving their contamination problem was extremely urgent. In this work, a novel Fe3O4-terephthalaldehyde (Fe3O4-TERE) magnetic nanomaterial was fabricated by introducing aromatic rings onto Fe3O4 nanoparticles through encapsulation and grafting technique. The Fe3O4 core provided convenience for the subsequent recycling and regeneration. The grafted aromatic carbons could act as adsorption active sites to form 7C-7C interaction with PENE/9-PENE's aromatic rings, thus improving the capture performance. The properties of the prepared magnetic nanomaterials were investigated via multiple characterization techniques. As expected, the Fe3O4-TERE could be utilized for effectively reducing the contamination risk of PENE and 9-PENE. Furthermore, the Fe3O4-TERE possessed with excellent regeneration performance. The abundant homogeneous reaction sites of Fe3O4-TERE provided possibility for the monolayer adsorption of PENE and 9-PENE. There were multiple microscopic interactions and driving forces jointly or individually participated the multi-stage adsorption reaction. Moreover, density functional theory calculations not only analyzed the validity and existence form of the 7C-7C interaction under different adsorption configuration modes, but also provided deeply perspectives related to the microscopic bonding mechanism. This work proposed a promising fabrication strategy for magnetic nanomaterials used for removing and remediation of polycyclic aromatic hydrocarbons contamination, as well as provided profound theoretical perspectives for analyzing the adsorption mechanism
Fe3O4-4,4 '-biphenyldicarboxaldehyde superparamagnetic-nanomaterial for the high-efficiency removal of 9-phenanthrol: experimental combined with DFT investigations
No full textOwing to the more significant health and environmental risks of 9-phenanthrol (9-PROL) compared to phenanthrene, it is imminent to solve the 9-PROL pollution issue. Herein, Fe3O4-0.75-4,4 '-biphenyldicarboxaldehyde (Fe3O4-0.75BIPHENY) was synthesized via a silane coupling reaction and condensation reaction and employed as an efficient nanocomposite for the removal of 9-PROL. The magnetic core provided the possibility for its fast and convenient separation and the aromatic rings on the BIPHENY shell contributed to improving the capturing ability of 9-PROL molecules via the formation of pi-pi interactions. Multiple characterization techniques were employed to obtain a comprehensive understanding of the prepared magnetic adsorbents. Fe3O4-0.75BIPHENY not only exhibited an excellent adsorption performance towards 9-PROL, but also showed a relatively excellent regeneration performance. The homogeneous surface of Fe3O4-0.75BIPHENY provided adsorption sites for the adsorption of 9-PROL molecules, which adhered in monolayer molecular form. Importantly, density functional theory calculations provided novel deep insights into the most possible adsorption bonding mode and verified that pi-pi interactions existed in the offset stacking form. Furthermore, the visible electrostatic potential and energy orbital distribution plots demonstrated the validity of the adsorption reaction and stability of a specific configuration. This study provides guidance for the assembly of novel magnetic nanocomposites for alleviating traditional and secondary pollution caused by polycyclic aromatic hydrocarbons
HIGH PERFORMANCE COMPUTING FOR DSM EXTRACTION FROM ZY-3 TRI-STEREO IMAGERY
No full textZY-3 has been acquiring high quality imagery since its launch in 2012 and its tri-stereo (three-view or three-line-array) imagery has become one of the top choices for extracting DSM (Digital Surface Model) products in China over the past few years. The ZY-3 tri-stereo sensors offer users the ability to capture imagery over large regions including an entire territory of a country, such as China, resulting in a large volume of ZY-3 tri-stereo scenes which require timely (e.g., near real time) processing, something that is not currently possible using traditional photogrammetry workstations. This paper presents a high performance computing solution which can efficiently and automatically extract DSM products from ZY-3 tri-stereo imagery. The high performance computing solution leverages certain parallel computing technologies to accelerate computation within an individual scene and then deploys a distributed computing technology to increase the overall data throughput in a robust and efficient manner. By taking advantage of the inherent efficiencies within the high performance computing environment, the DSM extraction process can exploit all combinations offered from a set of tri-stereo images (forward-backword, forward-nadir and backword-nadir). The DSM results merged from all of the potential combinations can minimize blunders (e.g., incorrect matches) and also offer the ability to remove potential occlusions which may exist in a single stereo pair, resulting in improved accuracy and quality versus those that are not merged. Accelerated performance is inherent within each of the individual steps of the DSM extraction workflow, including the collection of ground control points and tie points, image bundle adjustment, the creation of epipolar images, and computing elevations. Preliminary experiments over a large area in China have proven that the high performance computing system can generate high quality and accurate DSM products in a rapid manner
Exergoeconomic evaluation of novel solid oxide fuel cell-integrated solar combined cycle with different solar integration modes
No full textThe active use of fuel cells and solar energy in power generation systems can help reduce fossil energy consumption and improve the work capacity of the system, which is an important means to achieve the goal of "carbon neutrality". In this study, novel solid oxide fuel cell-integrated solar combined cycle systems with different solar integration modes are proposed and investigated. The thermodynamic, environmental and economic performances of new systems with different solar collector integration modes are evaluated using the exergoeconomic theory and environmental performance analysis. The results show that when the new system uses trough solar collectors to replace part of the heating load of the second-stage high-pressure economizer and high-pressure boiler drum, the system has the highest exergy efficiency (52.91%), the lowest unit exergoeconomic cost (0.102109 $/kWh) and the lowest specific CO2 emission rate (475.27 g/kWh). When the operating conditions of the system remain unchanged, this solar energy integration mode has the highest solar-toelectricity efficiency (26.69%) as well as thermal-to-electricity efficiency (44.22%), and can obtain the best profit in the same operating life. The new system can attain maximum energy efficiency and optimal economic benefits by using this solar energy integration mode. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved
KELVIN-HELMHOLTZ INSTABILITY IN COLLISIONLESS SPACE PLASMAS
No full textPhysics, Fluids & PlasmasSCI(E)9ARTICLE2440-447
Global Methane Retrieval, Monitoring, and Quantification in Hotspot Regions Based on AHSI/ZY-1 Satellite
No full textMethane is the second largest greenhouse gas. The detection of methane super-emitters and the quantification of their emission rates are necessary for the implementation of methane emission reduction policies to mitigate global warming. High-spectral-resolution satellites such as Gaofen-5 (GF-5), EMIT, GHGSat, and MethaneSAT have been successfully employed to detect and quantify methane point source leaks. In this study, a matched filter (MF) algorithm is improved using data from the EMIT instrument and applied to data from the Advanced Hyperspectral Imager (AHSI) onboard the Ziyuan-1 (ZY-1) satellite. Validation by comparison with EMIT′s L2 XCH4 products shows the good performance of the improved MF algorithm, in spite of the lower spectral resolution of AHSI/ZY-1 in comparison with other point source imagers. The improved MF algorithm applied to AHSI/ZY-1 data was used to detect and quantify methane super-emitters in global methane hotspot regions. The results show that the improved MF algorithm effectively suppresses noise in retrieval results over both land and ocean surfaces, enhancing algorithm robustness. Sixteen methane plumes were detected in global hotspot regions, originating from coal mines, oil and gas fields, and landfills, with emission rates ranging from 0.57 to 78.85 t/h. The largest plume was located at an offshore oil and gas field in the Gulf of Mexico, with instantaneous emissions nearly equal to the combined total of the other 15 plumes. The findings demonstrate that AHSI, despite its lower spectral resolution, can detect sources with emission rates as small as 571 kg/h and achieve faster retrieval speeds, showing significant potential for global methane monitoring. Additionally, this study highlights the need to focus on methane emissions from marine sources, alongside terrestrial sources, to efficiently implement reduction strategies
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