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Xiaohan Liu,Xiao Liang,Kaiyue Gong,Siqi An,Xu Peng,Jun Cai,Xinyu Zhu,Chao Zhou 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.8
The three-phase cascaded H-bridge rectifier (CHBR) is widely used in high power and high voltage applications. This paper focuses on the load removed from the DC port of a three-phase CHBR, which can cause single-phase DC-port voltage unbalance issues and three-phases DC-port voltage unbalance issues. This paper proposes a voltage balance control strategy based on negative sequence current injection for three-phase CHBR to deal with the unbalance problem. An individual DC-port voltage control strategy is designed to balance the DC-port voltage in the faulty phase. In addition, a negative sequence current injection control strategy is responsible for balancing the DC-port voltages in the three phase CHBR. The effectiveness and feasibility of the proposed voltage control strategy based on negative sequence current injection is verified by the experimental results.
Deli Jia,Xiaohan Pei,He Liu,Caihao Cui,Yong Yu,Meiqi Liu 보안공학연구지원센터 2014 International Journal of Smart Home Vol.8 No.6
In order to optimize the technological process of the water distributor and do further sturdy about the interference pattern of the injection layers in China, we needs reasonable and reliable methods to obtain the dynamic parameters of water injection layers. In this paper, a novel DC power line carrier technology based on the Orthogonal Frequency Division Multiplexing (OFDM) technology is proposed, aiming to save the difficult communication problem between the underground and the surface. Using the signals on the power line, it includes the modulation and demodulation techniques and filter encoding technology to transmit the data. Experimental results show that this new communication technology has high noise resistance and low error rate, provides reliable technology support and data to optimize the injection process and build the model of the dynamic parameters change among all the layers.
Deli Jia,Xiaohan Pei,He Liu,Fuchao Sun,Mingxin Zhao 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.12
Integrated separate layer water injection technology is an effective approach to reduce the workload of injection oilfield. The primary equipment which consists of flowmeter, motor and control value is placed underground for a long time. Injection rate allocation fault diagnosis is a problem with character of multiformity. The fault symptoms and reasons are random, and it is hard to differentiate them. Weighted fuzzy C-means clustering algorithm combining symptoms signals and fuzzy mathematics approach is used on the technology. The algorithm is based on fuzzy C-means clustering algorithm, and increase weight to each fault sample to reduce the impact of samples on fault classifications. Simulation and analysis illustrates that the algorithm is able to reflect the real structure of the sample data. And it improves the accuracy of fault classification.
Elasto-plastic time history analysis of an asymmetrical twin-tower rigid-connected structure
Xiaohan Wu,Yanfei Sun,Mingzhuo Rui,Min Yan,Lishu Li,Dongze Liu 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.2
The structure analyzed in this paper has particular building style and special structural system. It is a rigid-connected twin-tower skyscraper with asymmetrical distribution of stiffness and masses in two towers. Because of the different stiffness between the north and the south towers, the torsion seismic vibration is significant. In this paper, in order to study the seismic response of the structure under both frequent low-intensity earthquakes as well as rare earthquakes at the levels of intensity 7, the analysis model is built and analyzed with NosaCAD. NosaCAD is an nonlinear structure analysis software based on second-development of AutoCAD with ObjectARX. It has convenient modeling function, high computational efficiency and diversity post-processing functions. The deformations, forces and damages of the structure are investigated based on the analysis. According to the analysis, there is no damage on the structure under frequent earthquakes, and the structure has sufficient capacity and ductility to resist rare earthquakes. Therefore the structure can reach the goal of no damage under frequent earthquakes and no collapse under rare earthquakes. The deformation of the structure is below the limit in Chinese code. The time sequence and distribution of damages on tubes are reasonable, which can dissipate some dynamic energy. At last, according to forces, load-carrying capacity and damage of elements, there are some suggestions on increasing the reinforcement in the core tube at base and in stiffened stories.
Thermal Oxidation of WSe<sub>2</sub> Nanosheets Adhered on SiO<sub>2</sub>/Si Substrates
Liu, Yingnan,Tan, Cheng,Chou, Harry,Nayak, Avinash,Wu, Di,Ghosh, Rudresh,Chang, Hsiao-Yu,Hao, Yufeng,Wang, Xiaohan,Kim, Joon-Seok,Piner, Richard,Ruoff, Rodney S.,Akinwande, Deji,Lai, Keji American Chemical Society 2015 NANO LETTERS Vol.15 No.8
<P>Because of the drastically different intralayer versus interlayer bonding strengths, the mechanical, thermal, and electrical properties of two-dimensional (2D) materials are highly anisotropic between the in-plane and out-of-plane directions. The structural anisotropy may also play a role in chemical reactions, such as oxidation, reduction, and etching. Here, the composition, structure, and electrical properties of mechanically exfoliated WSe<SUB>2</SUB> nanosheets on SiO<SUB>2</SUB>/Si substrates were studied as a function of the extent of thermal oxidation. A major component of the oxidation, as indicated from optical and Raman data, starts from the nanosheet edges and propagates laterally toward the center. Partial oxidation also occurs in certain areas at the surface of the flakes, which are shown to be highly conductive by microwave impedance microscopy. Using secondary ion mass spectroscopy, we also observed extensive oxidation at the WSe<SUB>2</SUB>–SiO<SUB>2</SUB> interface. The combination of multiple microcopy methods can thus provide vital information on the spatial evolution of chemical reactions on 2D materials and the nanoscale electrical properties of the reaction products.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2015/nalefd.2015.15.issue-8/acs.nanolett.5b02069/production/images/medium/nl-2015-02069p_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl5b02069'>ACS Electronic Supporting Info</A></P>
Capacitors Energy Strategy Based Cascaded H-Bridge Converter for DC Port Failures
Peng, Xu,Liu, Xiaohan,Yang, Guolong,Liu, Xijun,Gao, Lixia,Zhu, Xinyu The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5
In this paper, a capacitors energy strategy based Cascaded H-bridge Converter (CHBC) for steady DC link voltage is proposed, which allow the CHBC to work while DC power fails. The topology of the CHBC is analyzed to construct the proposed strategy. The capacitors energy strategy is deduced based on the principle that the DC link voltage should be steady, the switch state should be smooth and the switch frequency should be normal. Experiments based on a three-module prototype, including static experiment, start experiment and step change experiment, proves the correctness of the strategy. They also verified the excellent fault tolerance ability and good dynamic performance of the proposed strategy.
Capacitors Energy Strategy Based Cascaded H-Bridge Converter for DC Port Failures
Xu Peng,Xiaohan Liu,Guolong Yang,Xijun Liu,Lixia Gao,Xinyu Zhu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5
In this paper, a capacitors energy strategy based Cascaded H-bridge Converter (CHBC) for steady DC link voltage is proposed, which allow the CHBC to work while DC power fails. The topology of the CHBC is analyzed to construct the proposed strategy. The capacitors energy strategy is deduced based on the principle that the DC link voltage should be steady, the switch state should be smooth and the switch frequency should be normal. Experiments based on a three-module prototype, including static experiment, start experiment and step change experiment, proves the correctness of the strategy. They also verified the excellent fault tolerance ability and good dynamic performance of the proposed strategy.
Investigating the Characteristics of Wet Shotcrete Pipeline Transportation
Lianjun Chen,Jiahao Sun,Xiaohan Guo,Nan Guo,Yanan Huang,Guoming Liu 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.12
In order to study the resistance characteristics of wet shotcrete pipeline transportation, a small pipe type rheology and resistance test device was developed. The device is used for straight pipe resistance test, pump stop test and dyed concrete test were carried out on concrete with different characteristics. The fluidity changes of concrete with different characteristics were obtained through experiments. The results show that the slump, pressure bleeding rate, water-cement ratio were all negatively related to pipeline transportation resistance. The influence of the three factors on resistance was in order: pressure bleeding rate, water-cement ratio, slump. The dyed concrete test confirmed the principle of the plunger flow in the pipeline when concrete is pumped. The thickness of the lubricating layer increased with the increase of the water-cement ratio. The concrete pipeline transportation resistance increased with the increase of the standing time. The fitting curve was obtained through the correlation analysis between resistance and lubricating layer thickness, and the two were negatively correlated. This provides a new research idea for the study of drag reduction measures for concrete pipeline transportation.