Accurate Voltage Parameter Estimation for Grid Synchronization in Single-Phase Power Systems

Dai, Zhiyong,Lin, Hui,Tian, Yanjun,Yao, Wenli,Yin, Hang The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

This paper presents an adaptive observer-based approach to estimate voltage parameters, including frequency, amplitude, and phase angle, for single-phase power systems. In contrast to most existing estimation methods of grid voltage parameters, in this study, grid voltage is treated as a dynamic system related to an unknown grid frequency. Based on adaptive observer theory, a full-order adaptive observer is proposed to estimate voltage parameters. A Lyapunov function-based argument is employed to ensure that the proposed estimation method of voltage parameters has zero steady-state error, even when frequency varies or phase angle jumps significantly. Meanwhile, a reduced-order adaptive observer is designed as the simplified version of the proposed full-order observer. Compared with the frequency-adaptive virtual flux estimation, the proposed adaptive observers exhibit better dynamic response to track the actual grid voltage frequency, amplitude, and phase angle. Simulations and experiments have been conducted to validate the effectiveness of the proposed observers.

Accurate Voltage Parameter Estimation for Grid Synchronization in Single-Phase Power Systems

Zhiyong Dai,Hui Lin,Yanjun Tian,Wenli Yao,Hang Yin 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

This paper presents an adaptive observer-based approach to estimate voltage parameters, including frequency, amplitude, and phase angle, for single-phase power systems. In contrast to most existing estimation methods of grid voltage parameters, in this study, grid voltage is treated as a dynamic system related to an unknown grid frequency. Based on adaptive observer theory, a full-order adaptive observer is proposed to estimate voltage parameters. A Lyapunov function-based argument is employed to ensure that the proposed estimation method of voltage parameters has zero steady-state error, even when frequency varies or phase angle jumps significantly. Meanwhile, a reduced-order adaptive observer is designed as the simplified version of the proposed full-order observer. Compared with the frequency-adaptive virtual flux estimation, the proposed adaptive observers exhibit better dynamic response to track the actual grid voltage frequency, amplitude, and phase angle. Simulations and experiments have been conducted to validate the effectiveness of the proposed observers.

Joint Adaptive Combining and Variable Tap-Length Multiuser Detector for Underwater Acoustic Cooperative Communication

( Zhiyong Liu ),( Yinghua Wang ),( Lizhong Song ),( Yinyin Wang ),( Fusheng Dai ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.1

In this paper, we propose a joint adaptive combining and variable tap-length multiuser detector (MUD) for amplify-and-forward (AF) underwater acoustic cooperative interleave-division multiple access (IDMA) communication system. The proposed MUD jointly realizes tap-length adjustment, adaptive combining, and multiuser detection. In contrast to the existing methods, the proposed detector can adaptively combine the received signals from different nodes at destination, and does not need the assumption that full and perfect channel state information (CSI) of all the links at the receiver is known. Moreover, the proposed detector can adaptively adjust the tap coefficient vector and tap-length of each branch according to the specific channel profile of each branch. Simulation results validate the feasibility and show the advantages of the proposed detector against existing counterparts.

Frequency characteristics and sensitivity analysis of a size-dependent laminated nanoshell

Dai, Zuocai,Jiang, Zhiyong,Zhang, Liang,Habibi, Mostafa Techno-Press 2021 Advances in nano research Vol.10 No.2

In this article, frequency characteristics, and sensitivity analysis of a size-dependent laminated composite cylindrical nanoshell under bi-directional thermal loading using Nonlocal Strain-stress Gradient Theory (NSGT) are presented. The governing equations of the laminated composite cylindrical nanoshell in thermal environment are developed using Hamilton's principle. The thermodynamic equations of the laminated cylindrical nanoshell are obtained using First-order Shear Deformation Theory (FSDT) and Fourier-expansion based Generalized Differential Quadrature element Method (FGDQM) is implemented to solve these equations and obtain natural frequency and critical temperature of the presented model. The novelty of the current study is to consider the effects of bi-directional temperature loading and sensitivity parameter on the critical temperature and frequency characteristics of the laminated composite nanostructure. Apart from semi-numerical solution, a finite element model was presented using the finite element package to simulate the response of the laminated cylindrical shell. The results created from finite element simulation illustrates a close agreement with the semi-numerical method results. Finally, the influences of temperature difference, ply angle, length scale and nonlocal parameters on the critical temperature, sensitivity, and frequency of the laminated composite nanostructure are investigated, in details.

Study of the Non-Linearity on TiO2(0 0 1) Surface with Oxygen Defects: A First-Principles Study

Yuehua Dai,Xu Zhang,Chengzhi Ma,Zhiyong Pan,Feifei Wang,Wenjuan Lu,Jin Yang,Fei Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.8

First-principles plane-wave pseudopotential calculations were performed to study the energetics and electronic structures of oxygen defects on rutile TiO2(0 0 1). The influence of the material thickness on non-linearity (NL) was studied. With the increase in the thickness, the NL became stronger. Calculating the site-projected density of states by applying an external electric field showed that the NL of the bulk is due to the exchange of electrons between O 2p orbitals and Ti 3d orbitals. Finally, the influence of oxygen defects—oxygen vacancies (Vo), oxygen interstitials (Oi), and oxygen vacancies/oxygen interstitial (Vo + Oi) pairs (Frenkel pair defects)—on the NL of TiO2 was studied. These results demonstrate that the band gap (Eg) of TiO2 became gradually narrower as the electric field increased. The Stark effect and defects can lead to the splitting of degenerate energy levels. Stronger electric fields increase the band splitting and reduce Eg. With the increase in the Vo concentration, the decrease in the splitting amplitude and width of the energy level lead to weakening of the transfer of electrons between O and Ti atoms and optimizing the NL of TiO2. Therefore, the incorporation of Vo plays a significant role in improving the NL of TiO2.

Fluoxetine Protects against Big Endothelin-1 Induced Anti-Apoptosis by Rescuing Kv1.5 Channels in Human Pulmonary Arterial Smooth Muscle Cells

FeiFeng Dai,ZhiFu Mao,Jun Xia,ShaoPing Zhu,ZhiYong Wu 연세대학교의과대학 2012 Yonsei medical journal Vol.53 No.4

Purpose: Pulmonary Kv channels are thought to play a crucial role in the regulation of cell proliferation and apoptosis. Previous studies have shown that fluoxetine upregulated the expression of Kv1.5 and prevented pulmonary arterial hypertension in monocrotaline-induced or hypoxia-induced rats and mice. The current study was designed to test how fluoxetine regulates Kv1.5 channels, subsequently promoting apoptosis in human PASMCs cultured in vitro. Materials and Methods: Human PASMCs were incubated with low-serum DMEM, ET-1, and fluoxetine with and without ET-1 separately for 72 h. Then the proliferation, apoptosis, and expression of TRPC1 and Kv1.5 were detected. Results: In the ET-1 induced group, the upregulation of TRPC1 and down regulation of Kv1.5 enhanced proliferation and anti-apoptosis,which was reversed when treated with fluoxetine. The decreased expression of TRPC1 increased the expression of Kv1.5, subsequently inhibiting proliferation while promoting apoptosis. Conclusion: The results from the present study suggested that fluoxetine protects against big endothelin-1 induced anti-apoptosis and rescues Kv1.5 channels in human pulmonary arterial smooth muscle cells, potentially by decreasing intracellular concentrations of Ca2+.

GM-CSF augmented the photothermal immunotherapeutic outcome of self-driving gold nanoparticles against colorectal cancer

Jie Dai,Jianmei Li,Yuqin Zhang,Qian Wen,Yun Lu,Yu Fan,Fancai Zeng,Zhiyong Qian,Yan Zhang,Shaozhi Fu 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Background Hypoxia is a frequent characteristic observed in solid tumors and is strongly associated with tumor metastasis, angiogenesis, and drug resistance. While the vasculature of hypoxic tumor tissues poses obstacles to the efficient administration of conventional drugs, it may prove advantageous in sustaining hyperthermia. Photothermal therapy (PTT) offers a promising treatment strategy that utilizes the activation of photosensitizers to produce heat, thus facilitating the selective ablation of tumor tissues. Method To enhance the accumulation of photothermal agents in tumor tissue and improve the effectiveness of PTT, we developed a self-propelled hybrid called Bif@PAu-NPs. This hybrid consists of polydopamine (PDA)-coated gold nanoparticles (Au-NPs) loaded onto the anaerobic Bifidobacterium infantis (Bif ). Results The Bif@PAu-NPs actively aggregated at the tumor site because the ability of Bif can target hypoxic regions, and PAu-NPs achieved precise PTT due to their high photothermal conversion efficiency (η = 67.8%). The tumor tissues were ablated by PTT, resulting in the release of antigens through immunogenic cell death (ICD), which stimulates an immune response. The inclusion of GM-CSF enhanced the immune response by recruiting dendritic cells and initiating long-term anti-tumor immunity. Conclusion The Bif@PAu-NPs hybrid effectively suppressed the growth of both primary tumors and re-challenged tumors. The utilization Bif@PAu-NPs in conjunction with GM-SCF exhibits great potential as a photothermal-immunotherapeutic strategy for precisely treating solid tumors.

Tracking Maneuvering Trajectory under a Boosted Kalman Filtering

Le Zhang,Zhiyong An,Yongping Hao,Qin Dai 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.12

In this paper, an adaptive Kalman Filtering method is presented for the state prediction of random systems. It is shown that the adaptive Kalman Filtering method in conjunction with equilibrium optimization solution can estimate the initial accelerations of targets effectively since the equilibrium optimization solution tunes the state prediction vector to diminish the error between measured value and prediction estimation value. We evaluate our model on special and random trajectories. Experimental evidence shows that the proposed method can robustly estimate an initial acceleration from a dynamic model and stably track a trajectory which is moving randomly.

Fabrication of carbon nanotube-loaded TiO2@AgI and its excellent performance in visible-light photocatalysis

Liu Yang,Yang An,Bin Dai,Xuhong Guo,Zhiyong Liu,Banghua Peng 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.2

Novel, visible light driven CNTs-TiO2@AgI hybrid materials were synthesized by a simple solvothermaldissolution- precipitation method, during which the acid vapor treated carbon nanotubes (CNTs) as template, AgI as sensitizer and TiO2 as the bridge unified them to form a ternary composite. The morphology and chemical components of as-prepared samples were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD and XPS characterizations indicated that anatase TiO2 and crystal AgI co-existed in the composite. HRTEM demonstrated CNTs were decorated with well-dispersed AgI and TiO2 nanoparticles (NPs), and TiO2 had an intimate connection with both AgI and CNTs. Diffusive reflectance UV-vis spectroscopy of CNTs-TiO2@AgI nanocomposite was extended to the whole UV-visible region due to adding of CNTs and AgI NPs. Degradation of Rhodamine B (RhB) polluted water using CNTs-TiO2@AgI NPs was carried out under visible light irradiation, and it showed higher degradation efficiency than CNTs-TiO2, TiO2@AgI, and CNTs@AgI NPs. The primary reason for the enhanced photocatalytic property was attributed to the synergic effect in CNTs-TiO2@AgI, which included the good adsorption ability and electrical conductivity of CNTs as well as the intimate connection and hetero-junctions among AgI, TiO2, and CNTs. Meanwhile, the as-prepared hybrid materials can be easily separated and reclaimed from the liquid phase, and the recycling tests indicated CNTs-TiO2@AgI had renewable performance.

3D PIC Method for Modeling and Simulating the Beam Transport System of a Linear Induction Accelerator

Yang Changhong,Meng Lin,Liu Da Gang,Zhang Kaizhi,Liao Shuqing,Dai Zhiyong 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61

Firstly, the method of combining the finite difference time domain with particle-in-cell code is used for simulating and modeling a accelerated section of the LIA, and on this basis, the numerical simulation of the solenoid coils and steering coils in accelerated section are completed by writing independent calculation module of magnetic components ,then on the platform of the MPICH2 message passing system, a proper method for parallel computing of more accelerate sections is provided and solved LIA's great scale problems. Finally, the 18 accelerated sections was simulated by the software, and compared with the envelope diagram of documents, which proved the correctness of the method used.