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Structure and morphological characteristics of polygonal salt crust, the West Juyan Lake, China
Guoming Zhang,Yuting Xiao,Mingzhu Xiang,Chang Hong,Bo-Tao Zhang,Lianyou Liu,Peijun Shi,Jifu Liu 한국지질과학협의회 2022 Geosciences Journal Vol.26 No.3
Polygonal salt crust patches (PSCPs) in modern playas have critical hydrologic implications for arid areas, but the morphology and origin of these polygonal features are under debate. This study investigated the structure and morphological characteristics of crustal landforms in a modern playa located in the West Juyan Lake, western Inner Mongolia of China, through an integrated analysis of high-resolution remote sensing images obtained from Google Earth, pedestrian field surveys, and unmanned aerial vehicle photography. The study area covers approximately 2,650 ha and the number of salt crust patches was 3,491. Across this area, the coverage and number of salt crust patches varied with elevation and sedimentary environment. The results show that the polygonal patch pattern of the salt crust landforms was fractal, and similar polygonal patch perimeter to area ratios and landscape index values prevail in the study area. The wind erosion of material on the surface of the Gobi Desert, a mountain torrent alluvial fan, and material carried by seasonal river water probably provided the provenance of the regional salt crust landforms. The structure and morphological characteristics of salt crust in typical playas of the arid and semiarid region are important for better understanding their composition and sedimentary environment. This study can help reveal relevant information regarding environmental change and provide a reference for saline dust emissions from playas in arid areas.
Guoming Wang,김우현,공정배,길경석,Hong-Keun Ji 한국전기전자재료학회 2018 Transactions on Electrical and Electronic Material Vol.19 No.3
This paper dealt with the application of transient earth voltage (TEV) sensors for the online measurement and analysis ofpartial discharge (PD) in medium-voltage switchboards. To simulate the typical insulation defects in the switchboards, fourtypes of artifi cial electrode systems, including high-voltage protrusion, low-voltage protrusion, particle-on-conductor, andvoid inside cast-resin potential transformer were fabricated. A TEV sensor with a frequency range of 1–150 MHz and anon-inductive resistor were used to detect the PD-induced TEV signal and the PD voltage pulse, respectively. The frequencyspectrums of TEV signals were analyzed, and it was found that they had a mutual frequency range of 5–50 MHz. However,the amplitude of TEV signal was not proportional to the apparent charge specifi ed in IEC 60270, resulting the diffi culty ofquantifi cation of PD. The phase-resolved partial discharge patterns were acquired using the TEV sensor and the developedmeasuring algorithm, by which distinguishable patterns were obtained from diff erent defects.
Optimal Design of a Follow Current Disconnector for DC Arresters in Traction Vehicles
Guoming Wang,,김선재,Seo-Jun Park,Gyung-Suk Kil,Hong-Keun Ji 한국전기전자재료학회 2016 Transactions on Electrical and Electronic Material Vol.17 No.5
This paper dealt with the optimal design of a follow current disconnector for DC arresters used in electric tractionvehicles. The disconnector separates the ground lead from an arrester to prevent a line-to-ground fault of an agedarrester and should not affect the operation and function such as the reference and the clamping voltage of theconnected arrester. The designed disconnector is composed of a resistor, a spark gap, and a cartridge. The resultsshowed that the sparkover voltage increased with the gap distance whereas the reference voltage was almost the sameas that without the disconnector. The sparkover voltage was 3.95 kV when the gap distance was 0.5 mm. Regardlessof the gap distance, the reference and the clamping voltage of the assembled disconnector with an arrester weremeasured to be the same as those of the arrester alone.
Design and Analysis of Additive Manufactured Flexure Hinge with Large Stroke and High Accuracy
Guoming Yao,Peng-Bo Liu,Shuaishuai Lu,Peng Yan 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.7
Additive manufacturing technology has significant potential for the development of advanced compliant mechanisms for precision manipulations owing to the advantage of realizing complex monolithic structures. By overcoming the limitations of traditional manufacturing technologies, this study develops a novel spatial spiral-based flexure hinge that aims to have a large stroke and high accuracy. In particular, the ∞-shaped configuration was adopted along the width direction of the flexure hinge by adjusting the spiral diameters. Owing to the excellent deformation capability and geometric constraints of the spatial spiral structure, the developed flexure hinge is capable of deflecting up to 90° with a small axis drift. The stiff - ness model of the flexure hinge was derived based on the elastic beam theory to illustrate the load–deflection relationships. The characteristics of the flexure hinge were further verified by finite element simulations and experiments on an additive manufactured prototype. Compared with the traditional flexure hinge, the developed design demonstrates a higher range and accuracy of rotation and a better ability to preserve the rotation center position but smaller compliance, which demonstrates a significant potential for emerging applications, including optical adjustments, biomedical operations, and robot joints.