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      • KCI등재

        Quadratic‑type high step‑up DC–DC converter with continuous input current integrating coupled inductor and voltage multiplier for renewable energy applications

        Fuwei Li,Jie He,Peng Luo,Haoyu Jiang,Mingxin Liu 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.4

        This paper presents a quadratic-type high step-up DC–DC converter for renewable energy applications with a continuousinput current. To reduce the number of components while increasing the gain, a quadratic boost converter and two multiplier cells are applied as the primary and secondary circuit with one coupled inductor connected. In addition, the clamp circuit shares its components with both the second boost stage and the voltage multiplier, which increases the power density. As a result, the leakage energy is recycled and the voltage stress can be suppressed. The operation principles and steady-state analyses including loss analysis of the proposed converter are addressed in detail. Compared with relevant existing topologies of quadratic converter, the proposed converter performs a higher voltage gain and a lower power switch stress. To validate the performance, a 200 W experimental prototype is constructed and tested with 20 V of input voltage and 400 V of output voltage, where the highest efficiency is 95.2% and the full-load efficiency is 93.7%. The performance under dynamic conditions is also verified. In the end, an improved topology based on the proposed converter is supplemented.

      • KCI등재

        Experimental and Numerical Investigation of Cross-Shaped Joints with Adjustable Stiffness for Cold-formed Thick-Walled Steel Column–Column Connections

        Li Zhanhong,Li Yuanqi,Wu Fuwei,Bai Xue,Ma Fudong 한국강구조학회 2024 International Journal of Steel Structures Vol.24 No.4

        Cold-formed thick-walled steel members have a higher bearing capacity and wider applicability in the mid-rise buildings in comparison with the widely-used cold-formed thin-walled steel framing walls in low-rise buildings. To avoid the shortcomings of cold-forming eff ect, a structure with hinged or semi-rigid joint steel frame using cold-formed thick-walled steel and cold-formed thin-walled steel framing shear wall is one reasonable choices, and it will be very helpful to simplify the on-site assembling processes. In this paper, a cross-shaped joint with adjustable stiff ness was proposed, and better seismic performance was investigated and confi rmed by tests. By increasing the thickness of the web plates of the cross-shaped joint, the bearing capacity, stiff ness, and ductility of the joint can be signifi cantly improved, and the buckling deformation of the web plate will be reduced. Moreover, a strengthening stiff ener, Type 2 proposed in the paper, has a signifi cantly eff ect on the cross-shaped joint for seismic damage and intact specimens. Using ANSYS software and the SOLID185 element, a fi nite element model was established. With the increasing thickness of the end plate of the stiff ener Type 2, both the stiff ness and bearing capacity of the cross-shaped joint can be signifi cantly increased.

      • SCISCIESCOPUS

        Solution-derived 40 µm vertically aligned ZnO nanowire arrays as photoelectrodes in dye-sensitized solar cells

        Qiu, Jijun,Li, Xiaomin,Zhuge, Fuwei,Gan, Xiaoyan,Gao, Xiangdong,He, Weizhen,Park, Se-Jeong,Kim, Hyung-Kook,Hwang, Yoon-Hwae IOP Pub 2010 Nanotechnology Vol.21 No.19

        <P>Well-aligned ZnO nanowire arrays with a long length of more than 40 mu m were prepared successfully by using the polyethylenimine (PEI)-assisted preheating hydrothermal method (PAPHT). Several important synthetic parameters such as PEI content, growth time, preheating time and zinc salt concentration were found to determine the growth of ultralong ZnO nanowire arrays, including length, diameter, density and alignment degree. The photoluminescence (PL) spectrum of as-grown ultralong ZnO nanowire arrays revealed a UV emission and a yellow emission, which was attributed to the absorbed hydroxyl group based on the peak shift after annealing in various atmospheres. The performance of dye-sensitized solar cells (DSSCs) increased with increasing length of ZnO nanowire arrays, which was mainly ascribed to the aggrandized photocurrent and reduced recombination loss according to electrochemical impedance spectroscopy (EIS). A maximum efficiency of 1.3% for a cell with a short-circuit current density (J(sc)) = 4.26 mA cm(2), open-circuit voltage (V-oc) = 0.69 V and (fill factor) FF = 0.42 was achieved with a length of 40 mu m.</P>

      • KCI등재

        A Sliding Mode Control Scheme for Steering Flexibility and Stability in All-wheel-steering Multi-axle Vehicles

        Tao Xu,Xuewu Ji,Xiangxin Liu,Zheng Li,Bo Feng,Fuwei Wu 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.6

        Multi-axle vehicles that have important roles in transport systems require high load-carrying capacity, steering performance, and stability. Thanks to the multiple steering characteristics, the dynamic performance of multi-axle vehicles can be greatly improved, which also brings great challenges for the design of their steering controller. Therefore, this paper proposes a steering control scheme for an all-wheel-steering multi-axle vehicle with the goal of optimizing low-speed steering flexibility and high-speed vehicle stability. With the dynamic analyses, the vehicle’s steady-state gains at different speeds are reshaped, which provide the closed-loop steering control system with good tracking performance. Correspondingly, a steering controller based on the sliding mode control approach is designed to control the steering angle of each wheel at different axles. The super-twisting control algorithm is also combined with a model-based observer to deal with disturbance while eliminating chattering effects of the control system. Simulation results based on a co-simulation platform verify the efficiency and disturbance rejection of the proposed control approach.

      • SCISCIESCOPUS

        Advantages of using Ti-mesh type electrodes for flexible dye-sensitized solar cells

        He, Weizhen,Qiu, Jijun,Zhuge, Fuwei,Li, Xiaomin,Lee, Jae-Ho,Kim, Yang-Do,Kim, Hyung-Kook,Hwang, Yoon-Hwae IOP Pub 2012 Nanotechnology Vol.23 No.22

        <P>We used Ti meshes for both the photoanodes and counter electrodes of dye-sensitized solar cells (DSSCs) to improve the flexibility and conductivity of the electrodes. These mesh type electrodes showed good transparency and high bendability when subjected to an external force. We demonstrated the advantages of cells using such electrodes compared to traditional transparent conducting oxide based electrodes and back side illuminated DSSCs, such as low sheet resistance, elevated photo-induced current and enhanced sunlight utilization. Nanotube layers of different thicknesses were investigated to determine their effect on the photovoltaic parameters of the cell. The overall efficiency of the best cells was approximately 5.3% under standard air mass 1.5 global (AM 1.5 G) solar conditions. Furthermore, the DSSCs showed an efficiency of approximately 3.15% due to the all Ti-mesh type electrodes even after illumination from the back side.</P>

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