A Bidirectional Dual Buck-Boost Voltage Balancer with Direct Coupling Based on a Burst-Mode Control Scheme for Low-Voltage Bipolar-Type DC Microgrids

Liu, Chuang,Zhu, Dawei,Zhang, Jia,Liu, Haiyang,Cai, Guowei The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

DC microgrids are considered as prospective systems because of their easy connection of distributed energy resources (DERs) and electric vehicles (EVs), reduction of conversion loss between dc output sources and loads, lack of reactive power issues, etc. These features make them very suitable for future industrial and commercial buildings' power systems. In addition, the bipolar-type dc system structure is more popular, because it provides two voltage levels for different power converters and loads. To keep voltage balanced in such a dc system, a bidirectional dual buck-boost voltage balancer with direct coupling is introduced based on P-cell and N-cell concepts. This results in greatly enhanced system reliability thanks to no shoot-through problems and lower switching losses with the help of power MOSFETs. In order to increase system efficiency and reliability, a novel burst-mode control strategy is proposed for the dual buck-boost voltage balancer. The basic operating principle, the current relations, and a small-signal model of the voltage balancer are analyzed under the burst-mode control scheme in detail. Finally, simulation experiments are performed and a laboratory unit with a 5kW unbalanced ability is constructed to verify the viability of the bidirectional dual buck-boost voltage balancer under the proposed burst-mode control scheme in low-voltage bipolar-type dc microgrids.

A Bidirectional Dual Buck-Boost Voltage Balancer with Direct Coupling Based on a Burst-Mode Control Scheme for Low-Voltage Bipolar-Type DC Microgrids

Chuang Liu,Dawei Zhu,Jia Zhang,Haiyang Liu,Guowei Cai 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

DC microgrids are considered as prospective systems because of their easy connection of distributed energy resources (DERs) and electric vehicles (EVs), reduction of conversion loss between dc output sources and loads, lack of reactive power issues, etc. These features make them very suitable for future industrial and commercial buildings’ power systems. In addition, the bipolar-type dc system structure is more popular, because it provides two voltage levels for different power converters and loads. To keep voltage balanced in such a dc system, a bidirectional dual buck-boost voltage balancer with direct coupling is introduced based on P-cell and N-cell concepts. This results in greatly enhanced system reliability thanks to no shoot-through problems and lower switching losses with the help of power MOSFETs. In order to increase system efficiency and reliability, a novel burst-mode control strategy is proposed for the dual buck-boost voltage balancer. The basic operating principle, the current relations, and a small-signal model of the voltage balancer are analyzed under the burst-mode control scheme in detail. Finally, simulation experiments are performed and a laboratory unit with a 5kW unbalanced ability is constructed to verify the viability of the bidirectional dual buck-boost voltage balancer under the proposed burst-mode control scheme in low-voltage bipolar-type dc microgrids.

Secondary Salient Feature Based GNN for Few-Shot Classification

Chuang Liu,Hu Pan 한국차세대컴퓨팅학회 2022 한국차세대컴퓨팅학회 학술대회 Vol.2022 No.10

The goal of few-shot learning is to use limited labeled samples to achieve effective classification results. To mine the features of images in the limited number of samples, some researchers proposed to mine salient features to improve the classification effect. However, they ignore the use of secondary salient features. Therefore, we propose to use secondary salient features to supplement the deficiency of salient features. Combining with the foreground extraction network and the graph neural network, a better classification effect is obtained in the experiment.

渤海陶器硏究의 現況과 問題点(2)

嚴長錄(Yien Chuang-liu) 한국학중앙연구원 1996 한국학 Vol.19 No.2

Genomic features of the fall armyworm (Spodoptera frugiperda) (J.E. Smith) yield insights into its defense system and flight capability

Chuang ZHOU,Lei Wang,Megan Price,Jing Liu,Yang MENG,Bisong Yue 한국곤충학회 2020 Entomological Research Vol.50 No.2

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) is an agriculturally important insect pest and causes significant economic loss due to its resistance to insecticide and high dispersal ability (i.e. long-distance flyer). We performed comparative genomics analysis based on the recently released chromosome-scale genome of the FAWto investigate the genetic mechanisms of FAWs defense system and flight ability. The gene families encoding receptors for bitter or toxic substances and detoxification enzymes, such as cytochrome P450, carboxylesterase and glutathione-S-transferase, were expanded in FAW, enabling its ability to detect and detoxify many plant secondary compounds. The chromosomal locations of five detoxification-related genes (i.e. ABC, CCE, GST, P450, and UGT) were analyzed, which revealed the density of these genes across the FAW genome. Several genes like Mio, Sik2, CRTC, and Lpin were positively selected in FAW, which were associated with energy metabolism, lipid metabolism, and/or muscle development, and thus possibly contributed to the high flight ability of FAW. We also analyzed the homologs to antimicrobial genes reported in the Drosophila genome, and identified 2 attacins, 6 cecropins, 3 gloverins, and 2 moricins in FAW. The findings of this study will broadly expand our knowledge on the biology of the devastating FAW, and contribute to the development of new pest management strategies for the control of major agricultural pests like FAW.

A Novel Guidance Algorithm for Underactuated Ship Path-Following Control Based on Marine Practice

Liu Junpo,Zhao Baigang,Liang Cailei,Niu Yuna,Zhang Chuang 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3

Ship path-following is necessary for both manned and unmanned ships. During ship navigation, the planned route consists of several waypoints rather than being an arbitrary curve. This makes it essential that practical guidance algorithms be able to track waypoints-based routes. To address this problem, this paper presents a novel guidance law that divides waypoints-based routes into two parts: straight segments and waypoint segments. To follow straight segments, a dynamic virtual vessel can be used to reduce tracking errors. However, when dealing with waypoint segments, a planning idea is adopted because of lacking effective reference signal for traditional guidance law. Having established an effective guidance law, a closed-loop gain shaping algorithm is used for the course controller. To validate the effectiveness of the proposed algorithm, a comparative simulation was carried out, with further tests on a high-quality navigation simulator, with it obtaining generally satisfactory results.

Influence of second order wave excitation loads on coupled response of an offshore floating wind turbine

Chuang, Zhenju,Liu, Shewen,Lu, Yu The Society of Naval Architects of Korea 2020 International Journal of Naval Architecture and Oc Vol.12 No.-

This paper presents an integrated analysis about dynamic performance of a Floating Offshore Wind Turbine (FOWT) OC4 DeepCwind with semi-submersible platform under real sea environment. The emphasis of this paper is to investigate how the wave mean drift force and slow-drift wave excitation load (Quadratic transfer function, namely QTF) influence the platform motions, mooring line tension and tower base bending moments. Second order potential theory is being used for computing linear and nonlinear wave effects, including first order wave force, mean drift force and slow-drift excitation loads. Morison model is utilized to account the viscous effect from fluid. This approach considers floating wind turbine as an integrated coupled system. Two time-domain solvers, SIMA (SIMO/RIFLEX/AERODYN) and FAST are being chosen to analyze the global response of the integrated coupled system under small, moderate and severe sea condition. Results show that second order mean drift force and slow-drift force will drift the floater away along wave propagation direction. At the same time, slow-drift force has larger effect than mean drift force. Also tension of the mooring line at fairlead and tower base loads are increased accordingly in all sea conditions under investigation.

Influence of second order wave excitation loads on coupled response of an offshore floating wind turbine

Chuang, Zhenju,Liu, Shewen,Lu, Yu The Society of Naval Architects of Korea 2020 International Journal of Naval Architecture and Oc Vol.12 No.1

This paper presents an integrated analysis about dynamic performance of a Floating Offshore Wind Turbine (FOWT) OC4 DeepCwind with semi-submersible platform under real sea environment. The emphasis of this paper is to investigate how the wave mean drift force and slow-drift wave excitation load (Quadratic transfer function, namely QTF) influence the platform motions, mooring line tension and tower base bending moments. Second order potential theory is being used for computing linear and nonlinear wave effects, including first order wave force, mean drift force and slow-drift excitation loads. Morison model is utilized to account the viscous effect from fluid. This approach considers floating wind turbine as an integrated coupled system. Two time-domain solvers, SIMA (SIMO/RIFLEX/AERODYN) and FAST are being chosen to analyze the global response of the integrated coupled system under small, moderate and severe sea condition. Results show that second order mean drift force and slow-drift force will drift the floater away along wave propagation direction. At the same time, slow-drift force has larger effect than mean drift force. Also tension of the mooring line at fairlead and tower base loads are increased accordingly in all sea conditions under investigation.

The blade shape optimization of a lowpressure axial fan using the surrogatebased multi-objective optimization method

Chuang Kong,Meng Wang,Tao Jin,Shaoliang Liu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1

As a core component of a fan, the blade has a decisive impact on the aerodynamic performance of a low-pressure axial flow fan. Due to the limitations of the classical fan design theory on considering the complex 3D internal flow, the spanwise distribution of blade stacking line and section profiles are usually hard to reach the best state. This paper builds a surrogate-assistant multi-objective optimization flow combined with CFD method to explore the optimum blade shape under two typical working conditions. A total of 16 parameters were selected for demonstrating the blade stacking line and section profiles, according to Morris one-ata-time sensitivity analysis. The objective and constraint functions were the fan’s total-to-static efficiency and static pressure rise, respectively. During the optimization, the surrogate models of all response functions were built using kriging models, on which the multi-objective genetic algorithm takes the exploration. The optimization results indicate that the maximum improvement of the efficiency is 1.26 % for low mass flow working condition and 5.47 % for high mass flow working condition. The optimized models tend to make the low-pressure zone distributed along the blade leading edge in the meridian view and to reduce the tip leakage vortex intensity. This paper provides a good practical demonstration of multi-objective fine optimization on the blade shape of a low-pressure axial flow fan.

Preliminary Study of the Liouduei Area Hakka Industry and Cultural Tourism Using Analytic Hierarchy Process Method

Chuang Lan-Ying,Liu Hui-Ling,Chen Jui-Ling,Kuo Shiunn-Der 세계문화관광학회 2011 Conference Proceedings Vol.12 No.-

Taiwan is an island of diverse ethnicities and each ethnic group has maintained its unique traditional industry and culture. The saying "Tung Flower in the North and Liouduei in the South" is commonly used to describe the Hakka communities in Taiwan. "Liouduei" is not an administrative district that could be found on the map. The term refers to the Kaohsiung and Pingtung Hakka settlement in Southern Taiwan. In recent years the Council for Hakka Affairs of the Executive Yuan and the local government has made significant efforts to cultivate and support local culture and industry development. They actively marketed the Hakka cultural industry internationally and connected the local Hakka industry with cultural tourism hoping to raise public awareness of Hakka culture and establish a sustainable Hakka industry in a long run. In this study key evaluation criteria and literature were collected and reviewed. And there were 5 evaluation component fields 16 evaluation criterion items drawn-up. The Analytic Hierarchy Process (AHP) method was applied to conduct the criteria evaluation analysis of the Liouduei area Hakka Industry and cultural tourism with the target groups including the municipal Hakka administrative agencies social organizations Hakka Industry Business and experts and scholars. The findings were summarized into a cohesive conclusion and the results of the analysis were provided for government agencies as future references for their work on the preservation of Hakka cultural tourism and promotion of Hakka industry. Overall the study suggested that the interviewees ranked "Product Quality Assurance"(0.303) as the most critical factor and ranked the "The Maintenance of Industry and Cultural "(0.299) as the second factor and "Government Subsidies and Promotion"(0.232) as the third factor and followed by "Economic Efficiency Improvement"(0.085) ranked as the fourth factor. Finally it ranked the "Hakka Industry Business Alliance" (0.081) as the fifth factor.