Parameter Optimization of the LC filters Based on Multiple Impact Factors for Cascaded H-bridge Dynamic Voltage Restorers

Guodong Chen,Miao Zhu,Xu Cai 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.1

The cascaded H-Bridge Dynamic Voltage Restorer (DVR) is used for protecting high voltage and large capacity loads from voltage sags. The LC filter in the DVR is needed to eliminate switching ripples, which also provides an accurate tracking feature in a certain frequency range. Therefore, the parameter optimization of the LC filter is especially important. In this paper, the value range functions for the inductance and capacitance in LC filters are discussed. Then, parameter variations under different conditions of voltage sags and power factors are analyzed. In addition, an optimized design method is also proposed with the consideration of multiple impact factors. A detailed optimization procedure is presented, and its validity is demonstrated by simulation and experimental results. Both results show that the proposed method can improve the LC filter design for a cascaded H-Bridge DVR and enhance the performance of the whole system.

Thickness effect on the stability of unipolar resistance switching in tin ferrite thin films

Guodong Gong,Changjin Wu,Pengfei Hu,Ying Li,Namic Kwon,Chunli Liu 한국물리학회 2016 Current Applied Physics Vol.16 No.9

We report the reproducible unipolar resistance switching behavior in Pt/SnFe2O4/Pt structures. The amorphous SnFe2O4 thin film was spin-coated on the Pt/TiO2/SiO2/Si substrate by a sol-gel method. The current-voltage characterization showed that as the spin coating cycles increased, the resistive switching (RS) characteristics became stable, and an excellent RS performance showing uniform set voltage distribution, stable resistance of both low resistance and high resistance states, and narrow reset current distribution can be obtained in SFO films with a thickness about 220 nm. Based on the conducting filament model, the variation of the RS behavior was ascribed to the increase of the electroforming voltage in the thicker films, which consequently induced more oxygen vacancies to participate in the RS process. Our results indicated that the electroforming voltage performs a significant role in the RS properties of the amorphous SnFe2O4 and the optimized RS behavior through the regulation of preparation process can be used for the resistance random access memory applications.

Barycentric Location Estimation for Wireless Network Indoors Localization

GuoDong Kang,Tanguy Perennou,Michel Diaz 보안공학연구지원센터 2009 International Journal of Hybrid Information Techno Vol.2 No.2

The localization requirements for mobile nodes in wireless (sensor) networks are increasing. However, most research works are based on range measurements between nodes which are often oversensitive to the measurement error. In this paper we propose a location estimation scheme based on moving nodes that opportunistically exchange known positions. The user couples a linear matrix inequality (LMI) method with a barycenter computation to estimate its position. Simulations have shown that the accuracy of the estimation increases when the number of known positions increases, the radio range decreases and the node speeds increase. The proposed method only depends on a maximum RSS threshold to take into account a known position, which makes it robust and easy to implement. To obtain an accuracy of 1 meter, a user may have to wait at the same position for 5 minutes, with 8 pedestrians moving within range on average.

Surface Reconstruction from Gradient Fields Using Box-Spline Kernel

Guodong Wang,Jingbao Yang,Yue Cheng 보안공학연구지원센터 2014 International Journal of Multimedia and Ubiquitous Vol.9 No.5

Estimates for certain shifted convolution sums involving Hecke eigenvalues

Guodong Hua 대한수학회 2023 대한수학회논문집 Vol.38 No.2

In this paper, we obtain certain estimates for averages of shifted convolution sums involving Hecke eigenvalues of classical holomorphic cusp forms. This generalizes some results of L\"{u} and Wang in this direction.

Effects of high-temperature stress and heat shock on two root maggots, Bradysia odoriphaga and Bradysia difformis (Diptera: Sciaridae)

Guodong Zhu,Yin Luo,Ming Xue,Haipeng Zhao,NanNan Xia,Xinhui Wang 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.1

Bradysia odoriphaga and B. difformis (Diptera: Sciaridae) are devastating pests of vegetables, ornamentals andedible mushrooms. In Chinese chive fields, the two Bradysia species occur with similar regularities: outbreaks inspring and autumn, and population decreases in summer. Temperature may be an important factor restrictingtheir population abundance in summer. Here, we performed a life-table study under constant high temperaturesand assessed the tolerance of two Bradysia species to heat shock. Life parameters of the Bradysia species indicatedslow developmental rates, and low survival rates and fecundity, when the temperature was higher than 30 °C. At34 °C, individuals were unable to reach the adult stages from eggs. Moreover, temperatures above 36 °C showedlethal effects, decreasing their survival rates. The median lethal time (LT50) values of 4th instar B. odoriphagaand B. difformis larvae were 46.82 and 32.97 h, respectively, while the values at 38 °C were 2.12 and 1.51 h,respectively. The 4th instar larvae and pupae possessed higher thermotolerance levels than adults and eggs,indicating sensitivities to heat stress. Moreover, B. odoriphaga was more thermotolerant than B. difformis. Thus,weak thermotolerance levels may restrict their occurrences during the period of summer heat, and the differencein thermotolerance levels between the two species may be related to their regional distributions.

Cystoscopic Extraction Technique and External Drainage Rescue of a Failed Attempt to Traverse a Severe Transplanted Ureteral Obstruction

Guodong Zhang,Yang Xu,Peng Jin,Zhiyong Xie,Gang Sun 대한비뇨의학회 2013 Investigative and Clinical Urology Vol.54 No.12

Purpose: The aim of this research was to evaluate the efficacy of the cystoscopic extraction and external drainage techniques for unsuccessful antegrade stenting in transplanted severe ureteral obstruction. Materials and Methods: A total of 26 patients with severe transplanted ureteral obstruction in whom the cystoscopic extraction technique and/or external drainage technique was performed were retrospectively evaluated. After the severe obstruction was successfully traversed, balloon dilatation followed by double-J stent insertion was performed. Results: Of the 26 patients (male:female, 9:4; mean age, 38.1 years) who underwent failed ureteral stenting with the conventional procedure, 16 patients underwent successful stenting with the cystoscopic extraction technique, and 10 patients underwent successful stenting following external drainage. The mean serum creatinine of the 26 patients before stenting was 42.9 mg/dL (range, 32.7 to 54.1 mg/dL), which decreased to 10.3 mg/dL (range, 8.7 to 11.8 mg/dL) after stenting. The complications of the procedure were lower abdominal pain in 22 patients and gross hematuria in 9 patients. All complications were relieved with medical care within 3 to 5 days after the procedure. No major complications occurred. Conclusions: The cystoscopic extraction technique and external drainage technique are safe and useful for traversing a severe transplanted ureteral obstruction after a failed conventional procedure.

Leakage Magnetic Field Suppression Using Dual-Transmitter Topology in EV Wireless Charging

Guodong Zhu,Dawei Gao,Shulin Lin 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

This paper proposes an active leakage magnetic field (LMF) suppression scheme, which uses the dual-transmitter (DT) topology, for EV wireless charging systems (EVWCS). The two transmitter coils are coplanar, concentric and driven by separate inverters. The LMF components generated by the three coils cancel each other out to reduce the total field strength. This paper gives a detailed theoretical analysis on the operating principles of the proposed scheme. Finite element analysis is used to simulate the LMF distribution patterns. Experimental results show that when there is no coil misalignment, 97% of the LMF strength can be suppressed in a 1kW prototype. These results also show that the impact on efficiency is small. The trade-off between LMF suppression and efficiency is revealed, and a control strategy to balance these two objectives is presented.

A remark on the exponential inequality for negatively associated random variables

Guodong Xing,Shanchao Yang,Ailin Liu,Xiangping Wang 한국통계학회 2009 Journal of the Korean Statistical Society Vol.38 No.1

We give an exponential inequality for negatively associated random variables. The inequality improves the corresponding result which was obtained in [Kim, T. S., & Kim, H. C. (2007). On the exponential inequality for negatively dependent sequence. Korean Mathematical Society. Communications, 22(2), 315321]. We also obtain the convergence rate n-1/2.log n3/2 for the strong law of large numbers, which improves the corresponding one obtained by the authors in the above-cited reference.

Synthesis of a novel phosphorus-containing plasticizer based on castor oil and its application for flame retardancy of polyvinyl chloride

Guodong Feng,Puyou Jia,Liqiang Zhang,Lihong Hu,Meng Zhang,Yonghong Zhou 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.6

A novel flame-retardant plasticizer based on castor oil (FRC) was synthesized, and its potential application for polyvinyl chloride (PVC) was evaluated through the study of torque during melt processing, thermogravimetric analysis (TGA), limiting oxygen index instrument, scanning electron microscope (SEM) and mechanical tests. The results suggested that the FRC has a plasticizing effect in blends with PVC. The addition of FRC resulted in reduction of processing torque, good compatibility, improvement in thermal stability and efficient flame retardant. Torque reduction was observed (33.6%), indicating the reduction of viscosity and the improvement of process. The increase (31.9%) of LOI value indicated that incorporation of FRC system had obviously improved the flame retardant property of PVC blends. The excellent flame retardant properties were obtained by forming an isolation layer on the surface of PVC blends in the process of FRC burning. FRC could improve the thermal ability of PVC blends by enhancing the decomposition temperature of PVC. The performance in all properties of PVC products could be obtained by controlling the formula blends. Therefore, castor oil-based flame retardant plasticizers would appear suitable for a wide range of application.