Er3+/Yb3+ Co-Doped Waveguide Amplifier and Lossless Power Splitter Fabricated by a Two-Step Ion Exchange on a Commercial Phosphate Glass

Zian He,Lei Xu,Dongxiao Li,Liying Liu,Yanwu Zhang,Yigang Li 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.5I

An Er3+/Yb3+ co-doped waveguide amplifier and a lossless power splitter were fabricated by two-step ion exchange on commercial Schott IOG-1 glasses. A two-dimensional ion exchange model was set up, and numerical simulations using a finite-element-method agreed well with experimental results. A total net gain of 6 dB was achieved in a 2.5-cm-long waveguide amplifier, and a lossless power splitter was successfully realized as well.kci

Robust Finite Time Stability of Fractional-order Linear Delayed Systems with Nonlinear Perturbations

Liping Chen,Yigang He,Ranchao Wu,Yi Chai,Lisheng Yin 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.3

This letter is concerned with robust stability of fractional-order linear delayed system with nonlinear perturbations over finite time interval. By using inequality technique, two new sufficient conditions for the finite time stability for such systems with order and are presented, respectively. A numerical example is presented to demonstrate the validity and feasibility of the obtained results.

Fault Diagnosis of Transformer Based on Self-powered RFID Sensor Tag and Improved HHT

Tao Wang,Yigang He,Bing Li,Tiancheng Shi 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.5

This work introduces a fault diagnosis method for transformer based on self-powered radio frequency identification (RFID) sensor tag and improved Hilbert-Huang transform (HHT). Consisted by RFID tag chip, power management circuit, MCU and accelerometer, the developed RFID sensor tag is used to acquire and wirelessly transmit the vibration signal. A customized power management including solar panel, low dropout (LDO) voltage regulator, supercapacitor and corresponding charging circuit is presented to guarantee constant DC power for the sensor tag. An improved band restricted empirical mode decomposition (BREMD) which is optimized by quantumbehaved particle swarm optimization (QPSO) algorithm is proposed to deal with the raw vibration signal. Compared with traditional methods, this improved BREMD method shows great superiority in reducing mode aliasing. Then, a promising fault diagnosis approach on the basis of Hilbert marginal spectrum variations is brought up. The measured results show that the presented power management circuit can generate 2.5V DC voltage for the rest of the sensor tag. The developed sensor tag can achieve a reliable communication distance of 17.8m in the test environment. Furthermore, the measurement results indicate the promising performance of fault diagnosis for transformer.

Fault Diagnosis of Transformer Based on Self-powered RFID Sensor Tag and Improved HHT

Wang, Tao,He, Yigang,Li, Bing,Shi, Tiancheng The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.5

This work introduces a fault diagnosis method for transformer based on self-powered radio frequency identification (RFID) sensor tag and improved Hilbert-Huang transform (HHT). Consisted by RFID tag chip, power management circuit, MCU and accelerometer, the developed RFID sensor tag is used to acquire and wirelessly transmit the vibration signal. A customized power management including solar panel, low dropout (LDO) voltage regulator, supercapacitor and corresponding charging circuit is presented to guarantee constant DC power for the sensor tag. An improved band restricted empirical mode decomposition (BREMD) which is optimized by quantum-behaved particle swarm optimization (QPSO) algorithm is proposed to deal with the raw vibration signal. Compared with traditional methods, this improved BREMD method shows great superiority in reducing mode aliasing. Then, a promising fault diagnosis approach on the basis of Hilbert marginal spectrum variations is brought up. The measured results show that the presented power management circuit can generate 2.5V DC voltage for the rest of the sensor tag. The developed sensor tag can achieve a reliable communication distance of 17.8m in the test environment. Furthermore, the measurement results indicate the promising performance of fault diagnosis for transformer.

Low Complexity Hybrid Precoding in Millimeter Wave Massive MIMO Systems

Tongtong Cheng,Yigang He,Yuting Wu,Shuguang Ning,Yongbo Sui,Yuan Huang 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.4

As a preprocessing operation of transmitter antennas, the hybrid precoding is restricted by the limited computing resources of the transmitter. Therefore, this paper proposes a novel hybrid precoding that guarantees the communication efficiency with low complexity and a fast computational speed. First, the analog and digital precoding matrix is derived from the maximum eigenvectors of the channel matrix in the sub-connected architecture to maximize the communication rate. Second, the extended power iteration (EPI) is utilized to obtain the maximum eigenvalues and their eigenvectors of the channel matrix, which reduces the computational complexity caused by the singular value decomposition (SVD). Third, the Aitken acceleration method is utilized to further improve the convergence rate of the EPI algorithm. Finally, the hybrid precoding based on the EPI method and the Aitken acceleration algorithm is evaluated in millimeter-wave (mmWave) massive multiple-input and multiple-output (MIMO) systems. The experimental results show that the proposed method can reduce the computational complexity with the high performance in mmWave massive MIMO systems. The method has the wide application prospect in future wireless communication systems.

A Self-Powered RFID Sensor Tag for Long-Term Temperature Monitoring in Substation

Zhongbin Chen,Fangming Deng,Yigang He,Zhen Liang,Zhihui Fu,Chaolong Zhang 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.1

Radio frequency identification (RFID) sensor tag provides several advantages including battery-less operation and low cost, which are suitable for long-term monitoring. This paper presents a self-powered RFID temperature sensor tag for online temperature monitoring in substation. The proposed sensor tag is used to measure and process the temperature of high voltage equipments in substation, and then wireless deliver the data. The proposed temperature sensor employs a novel phased-locked loop (PLL)-based architecture and can convert the temperature sensor in frequency domain without a reference clock, which can significantly improve the temperature accuracy. A twostage rectifier adopts a series of auxiliary floating rectifier to boost its gate voltage for higher power conversion efficiency. The sensor tag chip was fabricated in TSMC 0.18㎛ 1P6M CMOS process. The measurement results show that the proposed temperature sensor tag achieve a resolution of 0.15 ℃ /LSB and a temperature error of -0.6/0.7 ℃ within the range from -30 ℃ to 70 ℃. The proposed sensor tag achieves maximum communication distance of 11.8 m.

Influence of Thermal Expansion on Eccentricity and Critical Speed in Dry Submersible Induction Motors

Lv, Qiang,Bao, Xiaohua,He, Yigang The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.1

Rotor eccentricity is one of the major factors that directly influence the security of horizontal electrical machines, and the critical speed of the shaft has a close relationship with vibration. This paper deals with the influence of thermal expansion on the rotor eccentricity and critical speed in large dry submersible motors. The dynamic eccentricity (where the rotor is still turning around the stator bore centre but not its own centre) and critical speed of a three-phase squirrel-cage submersible induction motor are calculated via hybrid analytical/finite element method. Then the influence of thermal expansion is investigated by simulation. It is predicted from the study that the thermal expansion of the rotor and stator gives rise to a significant air-gap length decrement and an inconspicuous slower critical speed. The results show that the thermal expansion should be considered as an impact factor when designing the air gap length.

Influence of Thermal Expansion on Eccentricity and Critical Speed in Dry Submersible Induction Motors

Qiang Lv,Xiaohua Bao,Yigang He 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.1

Rotor eccentricity is one of the major factors that directly influence the security of horizontal electrical machines, and the critical speed of the shaft has a close relationship with vibration. This paper deals with the influence of thermal expansion on the rotor eccentricity and critical speed in large dry submersible motors. The dynamic eccentricity (where the rotor is still turning around the stator bore centre but not its own centre) and critical speed of a three-phase squirrelcage submersible induction motor are calculated via hybrid analytical/finite element method. Then the influence of thermal expansion is investigated by simulation. It is predicted from the study that the thermal expansion of the rotor and stator gives rise to a significant air-gap length decrement and an inconspicuous slower critical speed. The results show that the thermal expansion should be considered as an impact factor when designing the air gap length.

Inductances Evaluation of a Squirrel-Cage Induction Motor with Curved Dynamic Eccentricity

Qiang Lv,Xiaohua Bao,Yigang He,Yong Fang,Xiaowei Cheng 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

Eccentricity faults more or less exist in all rotating electrical machines. This paper establishes a more precise model of dynamic eccentricity (DE) in electrical machines named as curved dynamic eccentricity. It is a kind of axial unequal eccentricity which has not been investigated in detail so far but occurs in large electrical machines. The inductances of a large three-phase squirrel-cage induction machine (SCIM) under different levels of curved DE conditions are evaluated using winding function approach (WFA). These inductances include the stator self and mutual inductances, rotor self and mutual inductances, and mutual inductances between stator phases and rotor loops. A comparison is made between the calculation results under curved DE and the corresponding pure DE conditions. It indicates that the eccentricity condition will be more terrible than the monitored eccentricity based on the conventional pure DE model.

A Self-Powered RFID Sensor Tag for Long-Term Temperature Monitoring in Substation

Chen, Zhongbin,Deng, Fangming,He, Yigang,Liang, Zhen,Fu, Zhihui,Zhang, Chaolong The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.1

Radio frequency identification (RFID) sensor tag provides several advantages including battery-less operation and low cost, which are suitable for long-term monitoring. This paper presents a self-powered RFID temperature sensor tag for online temperature monitoring in substation. The proposed sensor tag is used to measure and process the temperature of high voltage equipments in substation, and then wireless deliver the data. The proposed temperature sensor employs a novel phased-locked loop (PLL)-based architecture and can convert the temperature sensor in frequency domain without a reference clock, which can significantly improve the temperature accuracy. A two-stage rectifier adopts a series of auxiliary floating rectifier to boost its gate voltage for higher power conversion efficiency. The sensor tag chip was fabricated in TSMC $0.18{\mu}m$ 1P6M CMOS process. The measurement results show that the proposed temperature sensor tag achieve a resolution of $0.15^{\circ}C$/LSB and a temperature error of $-0.6/0.7^{\circ}C$ within the range from $-30^{\circ}C$ to $70^{\circ}C$. The proposed sensor tag achieves maximum communication distance of 11.8 m.