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355. Remagnetization mechanisms in Triassic red beds from South China

Author

Jiang, Zhaoxia, Liu, Qingsong, Dekkers, Mark J., Zhao, Xiang, Roberts, Andrew P., Yang, Zhenyu, Jin, Chunsheng, Liu, Jianxing, and Paleomagnetism

Subjects
Geophysics, Geochemistry and Petrology, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), red beds, remagnetization, chemical remanent magnetization, detrital remanent magnetization, hematite, South China Block
Abstract

Paleogeographic reconstructions based on paleomagnetic data rely on the reliability of the natural remanent magnetization (NRM) as a primary geomagnetic signal. Remagnetizations, however, can be common in many rock types, including late Paleozoic and Mesozoic red beds, and they complicate paleogeographic interpretations. Extracting the primary NRM from partially remagnetized rocks, and understanding the remagnetization mechanism are important in these contexts. We carried out a systematic paleomagnetic study of red bed samples from the Triassic Huangmaqing Formation, Nanjing (32.0°N, 118.9°E), South China. Two NRM components carried by secondary and primary hematite are isolated in 47 of the 94 samples studied, where the latter component has a direction in stratigraphic coordinates of D=29.2°, I=34.6° (α95=10.9°, 47 samples from 6 sites) that yields a paleopole of λ=60.8°N, ϕ=228.1°E, dp/dm=12.5/7.2, which is consistent with Triassic pole positions for the South China Block. A secondary chemical remanent magnetization (CRM) (D=227.1°, I=80.8°, α95=7.3°) is documented in all 94 samples from 10 sites and is carried by pigmentary hematite that is inferred to have been generated by magnetite oxidation during orogenic activity. This secondary component has steep inclinations and is interpreted to have been influenced by a combination of the remanence carried by original parent magnetite, the orogenic stress field, and the prevailing geomagnetic field direction during deformation. This CRM direction is recorded commonly by red beds from the South China Block, and is significant for regional tectonic studies in the area.

Published
2017

357. Interval Type-2 FNN-Based Quantized Tracking Control for Hypersonic Flight Vehicles With Prescribed Performance.

Author

Gao, Yabin, Liu, Jianxing, Wang, Zhenhuan, and Wu, Ligang

Subjects
*HYPERSONIC planes, *ELEVATORS, *FUZZY neural networks, *ADAPTIVE control systems, *FLIGHT, *SOFT sets, *ARTIFICIAL satellite tracking
Abstract

This paper presents a tracking control scheme with quantization mechanism for hypersonic flight vehicles (HFVs) with prescribed performance using an interval type-2 fuzzy neural network (IT2FNN). A parameterized tracking error model of the HFV is derived with some considered uncertainties, which are approximated by an IT2FNN. The tracking control of the velocity and altitude of the HFV is designed by using a prescribed performance control technique. It allows that transient characteristics of the tracking errors can be improved and adjusted by some prescribed performance functions. According to an adaptive backstepping control design procedure, novel continuous control laws of the fuel equivalency ratio, canard deflection, and elevator deflection are designed with logarithmic quantization mechanism, for the sake of avoiding inadvertently increasing the effective gains of continuous controllers as well as reducing loads of the communication from controller unit to actuator unit. Besides, the limited tracking errors of the flight path angle and angle-of-attack can be achieved by applying the designed controllers. Finally, the presented tracking controllers with quantization mechanism are validated by comparative simulations. [ABSTRACT FROM AUTHOR]

Published
2021
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358. Vertical track irregularity analysis of high-speed railways on simply-supported beam bridges based on the virtual track inspection method.

Author

Gao, Tianci, Cong, Jianli, Wang, Ping, Liu, Jianxing, Wang, Yuan, and He, Qing

Abstract

Understanding the relationship between the static and dynamic track geometry irregularities is crucial for the proper maintenance of rail infrastructures and the reduction of on-site workload. This paper focuses on the analysis of the dynamic and static track irregularities on simply-supported beam bridges for high-speed railways. Based on the simulation of three-dimensional vehicle–track–bridge dynamics, a virtual track inspection method is proposed according to the measurement principle with the inertial reference. With the static irregularity provided as the initial input to the simulation model, the virtual track inspection of dynamic track irregularities is carried out considering different supporting structures, i.e. subgrade and bridges. Furthermore, the characteristics and advantages of the proposed model are investigated in the "rigid track structure". Then, using the virtual track inspection method, this paper analyzes the relationship between the dynamic and static track irregularities (in the vertical direction) on the simply-supported beam bridge in both the time and frequency domains with respect to different train speeds, and the simulation results are validated by real-world measurements. Numerical results show that the stiffness irregularity in the vertical direction is periodical, with the cycle length equal to the span of the bridge. Furthermore, there is an obvious linear relationship between the dynamic and static irregularities. Also, the regression coefficient increases with increasing vehicle speed. [ABSTRACT FROM AUTHOR]

Published
2021
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359. Multidecadally resolved polarity oscillations during a geomagnetic excursion

Author

Chou, Yu-Min, Jiang, Xiuyang, Liu, Qing-Song, Hu, Hsun-Ming, Wu, Chung-Che, Liu, Jianxing, Jiang, Zhaoxia, Lee, Teh-Quei, Wang, Chun-Chieh, Song, Yen-Fang, Chiang, Cheng-Cheng, Roberts, Andrew P., Zhao, Xiang, Chou, Yu-Min, Jiang, Xiuyang, Liu, Qing-Song, Hu, Hsun-Ming, Wu, Chung-Che, Liu, Jianxing, Jiang, Zhaoxia, Lee, Teh-Quei, Wang, Chun-Chieh, Song, Yen-Fang, Chiang, Cheng-Cheng, Roberts, Andrew P., and Zhao, Xiang

Abstract

Polarity reversals of the geomagnetic field have occurred through billions of years of Earth history and were first revealed in the early 20th century. Almost a century later, details of transitional field behavior during geomagnetic reversals and excursions remain poorly known. Here, we present a multidecadally resolved geomagnetic excursion record from a radioisotopically dated Chinese stalagmite at 107–91 thousand years before present with age precision of several decades. The duration of geomagnetic directional oscillations ranged from several centuries at 106–103 thousand years before present to millennia at 98–92 thousand years before present, with one abrupt reversal transition occurring in one to two centuries when the field was weakest. These features indicate prolonged geodynamo instability. Repeated asymmetrical interhemispheric polarity drifts associated with weak dipole fields likely originated in Earth’s deep interior. If such rapid polarity changes occurred in future, they could severely affect satellites and human society.

Published
2018

360. Extended State Observer-Based Sliding-Mode Control for Three-Phase Power Converters

Author

Liu, Jianxing, Vázquez Pérez, Sergio, Wu, Ligang, Márquez. Abraham, Gao, Huijun, García Franquelo, Leopoldo, Universidad de Sevilla. Departamento de Ingeniería Electrónica, and TIC109: Tecnologia Electronica

Abstract

This paper proposes an extended state observer (ESO) based second-order sliding-mode (SOSM) control for three-phase two-level grid-connected power converters. The proposed control technique forces the input currents to track the desired values, which can indirectly regulate the output voltage while achieving a user-defined power factor. The presented approach has two control loops. A current control loop based on an SOSM and a dc-link voltage regulation loop which consists of an ESO plus SOSM. In this work, the load connected to the dc-link capacitor is considered as an external disturbance. An ESO is used to asymptotically reject this external disturbance. Therefore, its design is considered in the control law derivation to achieve a high performance. Theoretical analysis is given to show the closed-loop behavior of the proposed controller and experimental results are presented to validate the control algorithm under a real power converter prototype

Published
2017

361. Reduction Process of Pellet Containing High Chromic Vanadium-Titanium Magnetite in Cohesive Zone

Author

Liu Jianxing, Mansheng Chu, Xiangxin Xue, Gongjin Cheng, and Zhenggen Liu

Subjects
Blast furnace, Materials science, Metallurgy, Metals and Alloys, Vanadium, chemistry.chemical_element, Atmospheric temperature range, engineering.material, Condensed Matter Physics, chemistry.chemical_compound, Chemical engineering, chemistry, Pellet, Materials Chemistry, engineering, Wüstite, Physical and Theoretical Chemistry, Softening, Magnetite, Titanium
Abstract

In the present study, the reduction process of pellet containing high chromic vanadium–titanium magnetite in cohesive zone has been investigated. To elucidate the reduction process including the softening and melting properties, structure changes and migration processes of valuable components (Fe, V, Ti, and Cr) in pellet containing high chromic vanadium–titanium magnetite in cohesive zone, the experiment was carried out at different temperatures and the pellet samples were analyzed by the methods of XRD, SEM, and chemical analysis. The results of reduction process show that the temperature range of cohesive zone of pellet is from 1087.9 to 1338.3 °C and the maximum differential pressure of the burden is 15 859 Pa at the temperature of 1291 °C. The reduction process of pellet was gradually conducted from outside to inside, which could form a layer of iron shell on the outer surface of the pellet. A lot of wustite could be generated in the core of pellet when the reduction temperature exceeded 1100 °C. The migration process of iron is Fe2O3 → Fe3O4 → FeO → Fe, while the generated FeO could react with SiO2 forming 2FeO · SiO2. The reduction process of titanium is Fe2O3 · 3TiO2 → Fe5TiO8 → Fe2TiO4 → FeTiO3 → Ti(O0.19C0.53N0.32) → Ti(C,N) → [Ti] and MgO · TiO2 → Ti(C,N) → [Ti]. The migration process of vanadium is V2O3 → VN, VC → [V] and the chromium oxide was reduced as follows: (Fe0.6Cr0.4)2O3 → FeCr2O4 → [Cr].

Published
2014

363. Supplementary material to "Laser frequency stabilization based on an universal sub-Doppler NICE-OHMS instrumentation for the potential application in atmospheric Lidar"

Author

Zhou, Yueting, primary, Liu, Jianxing, additional, Guo, Songjie, additional, Zhao, Gang, additional, Ma, Weiguang, additional, Cao, Zhensong, additional, Dong, Lei, additional, Zhang, Lei, additional, Yin, Wangbao, additional, Wu, Yongqian, additional, Xiao, Liantuan, additional, Ove, Axner, additional, and Jia, Suotang, additional

Published
2018
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364. Laser frequency stabilization based on an universal sub-Doppler NICE-OHMS instrumentation for the potential application in atmospheric Lidar

Author

Zhou, Yueting, primary, Liu, Jianxing, additional, Guo, Songjie, additional, Zhao, Gang, additional, Ma, Weiguang, additional, Cao, Zhensong, additional, Dong, Lei, additional, Zhang, Lei, additional, Yin, Wangbao, additional, Wu, Yongqian, additional, Xiao, Liantuan, additional, Ove, Axner, additional, and Jia, Suotang, additional

Published
2018
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365. Late Quaternary sedimentary evolution of the outer shelf of the East China Sea

Author

Xu, Taoyu, primary, Shi, Xuefa, additional, Liu, Shengfa, additional, Qiao, Shuqing, additional, Yao, Zhengquan, additional, Fang, Xisheng, additional, Wu, Yonghua, additional, Shan, Xin, additional, Liu, Jianxing, additional, Yang, Gang, additional, Liu, Chenguang, additional, Li, Xiaoyan, additional, Cui, Jingjing, additional, and Zhao, Quanhong, additional

Published
2018
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370. Multidecadally resolved polarity oscillations during a geomagnetic excursion

Author

Chou, Yu-Min, primary, Jiang, Xiuyang, additional, Liu, Qingsong, additional, Hu, Hsun-Ming, additional, Wu, Chung-Che, additional, Liu, Jianxing, additional, Jiang, Zhaoxia, additional, Lee, Teh-Quei, additional, Wang, Chun-Chieh, additional, Song, Yen-Fang, additional, Chiang, Cheng-Cheng, additional, Tan, Liangcheng, additional, Lone, Mahjoor A., additional, Pan, Yongxin, additional, Zhu, Rixiang, additional, He, Yaoqi, additional, Chou, Yu-Chen, additional, Tan, An-Hung, additional, Roberts, Andrew P., additional, Zhao, Xiang, additional, and Shen, Chuan-Chou, additional

Published
2018
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388. Extended State Observer-Based Sliding-Mode Control for Three-Phase Power Converters

Author

Universidad de Sevilla. Departamento de Ingeniería Electrónica, TIC109: Tecnologia Electronica, Liu, Jianxing, Vázquez Pérez, Sergio, Wu, Ligang, Márquez Alcaide, Abraham, Gao, Huijun, García Franquelo, Leopoldo, Universidad de Sevilla. Departamento de Ingeniería Electrónica, TIC109: Tecnologia Electronica, Liu, Jianxing, Vázquez Pérez, Sergio, Wu, Ligang, Márquez Alcaide, Abraham, Gao, Huijun, and García Franquelo, Leopoldo

Abstract

This paper proposes an extended state observer (ESO) based second-order sliding-mode (SOSM) control for three-phase two-level grid-connected power converters. The proposed control technique forces the input currents to track the desired values, which can indirectly regulate the output voltage while achieving a user-defined power factor. The presented approach has two control loops. A current control loop based on an SOSM and a dc-link voltage regulation loop which consists of an ESO plus SOSM. In this work, the load connected to the dc-link capacitor is considered as an external disturbance. An ESO is used to asymptotically reject this external disturbance. Therefore, its design is considered in the control law derivation to achieve a high performance. Theoretical analysis is given to show the closed-loop behavior of the proposed controller and experimental results are presented to validate the control algorithm under a real power converter prototype

Published
2017

389. Remagnetization mechanisms in Triassic red beds from South China

Author

Paleomagnetism, Jiang, Zhaoxia, Liu, Qingsong, Dekkers, Mark J., Zhao, Xiang, Roberts, Andrew P., Yang, Zhenyu, Jin, Chunsheng, Liu, Jianxing, Paleomagnetism, Jiang, Zhaoxia, Liu, Qingsong, Dekkers, Mark J., Zhao, Xiang, Roberts, Andrew P., Yang, Zhenyu, Jin, Chunsheng, and Liu, Jianxing

Published
2017

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