Series-connected PV MVDC Converter for Large Scale PV System

Huan Wang,Xinke Huang,Yibo Wang,Honghua Xu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper presents a novel series-connected PV MVDC converter for large scale PV plant. By analyzing the characteristic of the series-connection PV system, the topology of MVDC converter based on modular structure of input parallel and output series (IPOS) is presented. A novel reconfigurable topology is proposed for the module of the converter. By regulating of switches duty cycle, the module can be reconfigured to realize step-up or step-down mode. With the control strategy and reconfigurable module topology, the series-connected PV MVDC converter achieves wide input voltage range to adapt PV array characteristic and wide output voltage range to adapt to series-connection system requirement with a high efficiency. 5kV/80kW dc-dc module is developed. Series-connected PV converter with modules in IPOS connection is built in simulation environment. The simulation result and experiment result are presented in the paper.

A brain somatic RHEB doublet mutation causes focal cortical dysplasia type II

Shanshan Zhao,Zhenghui Li,Muxian Zhang,Lingliang Zhang,Honghua Zheng,Jinhuan Ning,Yanyan Wang,Feng-Peng Wang,Xiaobin Zhang,Hexia Gan,Yuanqing Wang,Xian Zhang,Hong Luo,Guojun Bu,Huaxi Xu,Yi Yao,Yun-wu 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

Focal cortical dysplasia type II (FCDII) is a cerebral cortex malformation characterized by local cortical structure disorganization, neuronal dysmorphology, and refractory epilepsy. Brain somatic mutations in several genes involved in the PI3K/AKT/mTOR pathway are associated with FCDII, but they are only found in a proportion of patients with FCDII. The genetic causes underlying the development FCDII in other patients remain unclear. Here, we carried out whole exome sequencing and targeted sequencing in paired brain–blood DNA from patients with FCDII and identified a brain somatic doublet mutation c.(A104T, C105A) in the Ras homolog, mTORC1 binding (RHEB) gene, which led to the RHEB p.Y35L mutation in one patient with FCDII. This RHEB mutation carrier had a dramatic increase of ribosomal protein S6 phosphorylation, indicating mTOR activation in the region of the brain lesion. The RHEB p.Y35L mutant protein had increased GTPλS-binding activity compared with wild-type RHEB. Overexpression of the RHEB p. Y35L variant in cultured cells also resulted in elevated S6 phosphorylation compared to wild-type RHEB. Importantly, in utero electroporation of the RHEB p.Y35L variant in mice induced S6 phosphorylation, cytomegalic neurons, dysregulated neuron migration, abnormal electroencephalogram, and seizures, all of which are found in patients with FCDII. Rapamycin treatment rescued abnormal electroencephalograms and alleviated seizures in these mice. These results demonstrate that brain somatic mutations in RHEB are also responsible for the pathogenesis of FCDII, indicating that aberrant activation of mTOR signaling is a primary driver and potential drug target for FCDII.

Synthesis of two kinds of phenolphthalein oligomers

Zhihong Liu,Honghua Wang,Tianlu Chen 한국고분자학회 2006 한국고분자학회 학술대회 연구논문 초록집 Vol.2006 No.10

Novel Islanding Detection Method for Distributed PV Systems with Multi-Inverters

Cao, Dufeng,Wang, Yi,Sun, Zhenao,Wang, Yibo,Xu, Honghua The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

This study proposes a novel islanding detection method for distributed photovoltaic (PV) systems with multi-inverters based on a combination of the power line carrier communication and Sandia frequency shift islanding detection methods. A parameter design method is provided for the novel scheme. On the basis of the designed parameters, the effect of frequency measurement errors and grid line impedance on the islanding detection performance of PV systems is analyzed. Experimental results show that the theoretical analysis is correct and that the novel method with the designed parameters has little effect on the power quality of the inverter output current. Non-detection zones are not observed, and a high degree of reliability is achieved. Moreover, the proposed islanding detection method is suitable for distributed PV systems with multi-inverters.

A Hybrid Cloud Testing System Based on Virtual Machines and Networks

( Jing Chen ),( Honghua Yan ),( Chunxiao Wang ),( Xuyan Liu ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.4

Traditional software testing typically uses many physical resources to manually build various test environments, resulting in high resource costs and long test time due to limited resources, especially for small enterprises. Cloud computing can provide sufficient low-cost virtual resources to alleviate these problems through the virtualization of physical resources. However, the provision of various test environments and services for implementing software testing rapidly and conveniently based on cloud computing is challenging. This paper proposes a multilayer cloud testing model based on cloud computing and implements a hybrid cloud testing system based on virtual machines (VMs) and networks. This system realizes the automatic and rapid creation of test environments and the remote use of test tools and test services. We conduct experiments on this system and evaluate its applicability in terms of the VM provision time, VM performance and virtual network performance. The experimental results demonstrate that the performance of the VMs and virtual networks is satisfactory and that this system can improve the test efficiency and reduce test costs through rapid virtual resource provision and convenient test services.

A novel multi-physics field optimization method for GaN HEMT circuit design

Zhang, Rui,Wang, Yibo,Xu, Honghua The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.3

A device modeling and topology design method suitable for high-power-density and high-temperature applicationare important to develop with the development of devices. A novel multi-physics analysis model based on GaN high electron mobility transistor (HEMT) is proposed in this paper. The coupled electromagnetic and electrothermal model for GaN HEMT is beneficial to simulate a device's external characteristic waveform affected by different stray parameters in the surrounding. In addition, the proposed method can accurately reflect the switching loss and transient switching process of GaN HEMT.

Quasi Z-Source based Full Bridge Isolated DC/DC Topology as A Basic Module for DC-Series PV Converter Connected to HVDC Grid

Xinke Huang,Huan Wang,Yibo Wang,Honghua Xu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

DC series-parallel photovoltaic (PV) plants have many advantages. As the most important equipment in the system, DC-Series DC/DC converter has some special technical requirements compared to other applications, especially, the wide input and output voltage regulation range requirement presents a unique challenge to the DC/DC converter design. The paper proposes a Quasi Z-Source based Full Bridge Isolated DC/DC Converter (QZS-FBIC) as a basic module, which cascaded through input parallel and output series (IPOS) to improve power capacity and output voltage adjustment range, so as to meet with the needs of the DC series-parallel PV generation system. The proposed converter can operate both in boost and buck mode. Besides some normal operating modules, several redundant modules are added, and all of these modules putting in and cutting out control to enlarge the range of the output voltage of the converter. A 20kV/500kW DC/DC converter model and 60kV/1.5MW system model are built in Matlab / Simulink to test the proposed topology and control strategies.

Novel Islanding Detection Method for Distributed PV Systems with Multi-Inverters

Dufeng Cao,Yi Wang,Zhenao Sun,Yibo Wang,Honghua Xu 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

This study proposes a novel islanding detection method for distributed photovoltaic (PV) systems with multi-inverters based on a combination of the power line carrier communication and Sandia frequency shift islanding detection methods. A parameter design method is provided for the novel scheme. On the basis of the designed parameters, the effect of frequency measurement errors and grid line impedance on the islanding detection performance of PV systems is analyzed. Experimental results show that the theoretical analysis is correct and that the novel method with the designed parameters has little effect on the power quality of the inverter output current. Non-detection zones are not observed, and a high degree of reliability is achieved. Moreover, the proposed islanding detection method is suitable for distributed PV systems with multi-inverters.

Model Tests of Jacked-Pile Penetration into Sand Using Transparent Soil and Incremental Particle Image Velocimetry

Cong Liu,Xiao-Wei Tang,Huanwei Wei,Pengpeng Wang,Honghua Zhao 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.4

This paper presents a series of physical modelling tests of jacked-pile penetration into sand, combining the transparent soil and incremental reliability-guided particle image velocimetry, which provides a non-intrusively internal deformation measurement approach to monitor the internal movement of soil caused by jacked-pile penetration. The difference between the full-model test and the half-model test was analyzed quantitatively for the first time. This paper aims to provide some new insight into the penetration mechanisms of different shapes of pile tip. In addition, the phenomenon of meta-stable sand plug in the process of jacked-pile penetration was studied by means of the method of partial replacement with dyed particles. Experimental evidence has shown that the boundary and interaction effect causes the experimental phenomenon of the half-model test to be different from the true condition. The shape effect of pile tip on the governing penetration mechanisms was discussed, and the disturbance effect of different shapes of pile tip was evaluated and compared based on a large number of model tests and published literatures. The paper intuitively demonstrates that the different penetration mechanism of flat-ended pile and cone-ended pile is mainly due to the formation of the meta-stable sand plug beneath the pile tip.

웹사이트 사용성 개선을 위한 통합 휴리스틱 평가 프레임워크 개발: 내부 정보 구조 강화를 위한 병행 접근

신지연(Jiyeon Shin),박정연(Jungyeon Park),배재후(Jaehoo Bae),려홍화(Lyu Honghua),이재인(Jane Lee),왕차이(Wang Cai),윤명환(Myung Hwan Yun) 한국HCI학회 2024 한국HCI학회 학술대회 Vol.2024 No.1

웹사이트는 기업의 서비스 운용 가치와 메세지를 효과적으로 전달할 수 있는 플랫폼이기에, 서비스 전달의 품질을 향상시키기 위해 설계 단계에서 사용자 중심적인 요소를 고려해야 한다. 그러나 초기단계의 소규모 기업들은 사용성 관련 업무를 수행하는데 최소한의 자원 배분을 통해 유지 보수를 위한 빠른 의사결정이 필요하다. 이에 웹사이트의 사용성 문제를 신속하게 평가하고 심각도와 원인을 식별하기 위한 휴리스틱 프레임워크를 제안한다. 이를 위해 본 연구는 신규 온라인 서비스 플랫폼 웹사이트의 문제점을 도출하고 주요 사용성 요소를 분류했다. 이후 검증된 기존의 휴리스틱 지표를 활용하여 해당 사용성 요소를 그룹화하고, 품질기능전개(Quality Function Deployment; QFD)의 방법론 중 House of Quality(HoQ) 매트릭스로 휴리스틱 통합 평가 프레임워크를 구축하였다. 마지막으로, 카드 소팅 방법론을 활용하여 웹사이트의 메뉴와 내비게이션 구조를 분석하여 초기 단계의 소규모 기업 웹사이트의 사용성을 다각적이고 포괄적으로 고려하여 사용성 개선의 프레임워크를 개발하였다. 따라서 문제점 별 위계에 따른 사용성 지표, 상관관계, 정보 구조의 개선을 통해 사용성의 다양한 측면을 고려하는 체계를 제시함으로써 사용자 중심의 웹사이트 설계에 큰 기여를 할 수 있음을 시사한다.