Neutron-irradiated effect on the thermoelectric properties of Bi2Te3-based thermoelectric leg

Zhao Huanyu,Liu Kai,Xu Zhiheng,Liu Yunpeng,Tang Xiaobin 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.8

Thermoelectric (TE) materials working in radioisotope thermoelectric generators are irradiated by neutrons throughout its service; thus, investigating the neutron irradiation stability of TE devices is necessary. Herein, the influence of neutron irradiation with fluences of 4.56 1010 and 1 1013 n/cm2 by pulsed neutron reactor on the electrical and thermal transport properties of n-type Bi2Te2.7Se0.3 and ptype Bi0.5Sb1.5Te3 thermoelectric alloys prepared by cold-pressing and molding is investigated. After neutron irradiation, the properties of thermoelectric materials fluctuate, which is related to the material type and irradiation fluence. Different from p-type thermoelectric materials, neutron irradiation has a positive effect on n-type Bi2Te2.7Se0.3 materials. This result might be due to the increase of carrier mobility and the optimization of electrical conductivity. Afterward, the effects of p-type and n-type TE devices with different treatments on the output performance of TE devices are further discussed. The positive and negative effects caused by irradiation can cancel each other to a certain extent. For TE devices paired with p-type Bi0.5Sb1.5Te3 and n-type Bi2Te2.7Se0.3 thermoelectric legs, the generated power and conversion efficiency are stable after neutron irradiation.

An LMI Approach to Consensus in Second-Order Multi-Agent Systems

Huanyu Zhao,Shengyuan Xu,Deming Yuan 제어·로봇·시스템학회 2011 International Journal of Control, Automation, and Vol.9 No.6

This paper deals with the consensus problem of the second-order multi-agent systems based on linear system theory. By a system transformation, the consensus problem is converted to the stability problem of a linear system. The second-order systems considered include the systems with both the fixed topology and the Markov switching topology. Necessary and sufficient conditions of consensus or mean square consensus are obtained. The results are extended to the cases of the uncertain transition probability rates and time-delay, respectively. Finally, a simulation example is given to show the effectiveness of the presented results.

Consensus for a Class of Sampled-data Heterogeneous Multi-agent Systems

Huanyu Zhao,Lei Wang,Hongbiao Zhou,Dongsheng Du 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.5

This paper investigates the problem of consensus for one kind of sampled-data heterogeneous multiagent system. We first discretize the continuous-time networked system by the method of sampled-data. Then we use a system transformation to transform the multi-agent system into the reduced-order error system. Two consensus algorithms with and without velocity measurement will be considered respectively. We obtain two sufficient conditions for the networked systems with and without velocity measurement to reach consensus through analyzing the stable problem of the reduced-order systems. Simulations are given to verify the effectiveness of the results.

Group consensus of discrete-time multi-agent systems with fixed and stochastic switching topologies

Zhao, Huanyu,Park, Ju H. Springer-Verlag 2014 Nonlinear dynamics Vol.77 No.4

Chief Executive Officer Succession and Financial Constraints: Evidence from China

Huanyu Ma,Xi Zhao 한국증권학회 2017 Asia-Pacific Journal of Financial Studies Vol.46 No.4

This study investigates the impact of Chief Executive Officer (CEO) succession on a firm’s financial constraints. Using panel data consisting of CEO turnover and non-turnover cases of listed companies in China, we find that new CEOs play a significant role in alleviating a firm’s financial constraints. Specifically, the level of cash holdings, the investment to cash flow sensitivity, and the cash to cash flow sensitivity all decline following a new CEO’s succession. These effects are stronger in cases where the turnovers are forced and the firms are more financially constrained.

Line-Interactive UPS for Low-Voltage Microgrids

Ping Zhang,Huanyu Cai,Hengyang Zhao,Jianjiang Shi,Xiangning He 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

Line-interactive uninterruptible power supply (UPS) systems are good candidates for providing energy storage within a microgrid. In this paper, a control scheme for a line-interactive UPS system applied in a low-voltage microgrid is presented. It is based on the Q-w and P-E droop control to achieve a seamless transition between grid-connected and stand-alone operation modes. Moreover, a new model for designing the controllers is built in the dq-frame based on the instantaneous power definition. The new-built model takes into account the dynamic performance of the output impedance of the inverter in the dq-frame and can be evaluated in the time domain. Compared to the traditional model based on the instantaneous power definition, the new-built model is more accurate to describe the dynamic performance of the system. Simulation and experimental results obtained with a microgrid consisting of two 40-kW line-interactive UPS systems are given to validate the control strategy of the line-active UPS system and the accuracy of the new-built model.

Line-Interactive UPS for Low-Voltage Microgrids

Zhang, Ping,Cai, Huanyu,Zhao, Hengyang,Shi, Jianjiang,He, Xiangning The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

Line-interactive uninterruptible power supply (UPS) systems are good candidates for providing energy storage within a microgrid. In this paper, a control scheme for a line-interactive UPS system applied in a low-voltage microgrid is presented. It is based on the Q-w and P-E droop control to achieve a seamless transition between grid-connected and stand-alone operation modes. Moreover, a new model for designing the controllers is built in the dq-frame based on the instantaneous power definition. The new-built model takes into account the dynamic performance of the output impedance of the inverter in the dq-frame and can be evaluated in the time domain. Compared to the traditional model based on the instantaneous power definition, the new-built model is more accurate to describe the dynamic performance of the system. Simulation and experimental results obtained with a microgrid consisting of two 40-kW line-interactive UPS systems are given to validate the control strategy of the line-active UPS system and the accuracy of the new-built model.

Robust Fault Diagnosis Observer Design for Uncertain Switched Systems

Dongsheng Du,Yue Yang,Huanyu Zhao,Yushun Tan 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.12

In order to improve the fault diagnosis theory of switched systems, observer-based method is proposed to deal with the fault diagnosis issue subjected to the parameter uncertainty, unknown process disturbances and unexpected faults. By employing proportional-integral observer (PIO) technique and the average dwell-time (ADT) method, an H∞/H− performance level is considered to ensure the worst case of robustness to the disturbance and sensitivity to the fault simultaneously. Moreover, the obtained fault diagnosis observer can give accurate fault estimation online for the piecewise constant fault. Finally, a two-tank system example is introduced in the end to show the effectiveness of the proposed results.

Study on electromechanical performance of steering of the electric articulated tracked vehicles

Jiaqi Wu,Guoqiang Wang,Huanyu Zhao,Kangkang Sun 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7

Articulated tracked vehicles (ATVs) usually use hydraulic drive or mechanical drive modes. Electrically driven tracked vehicles have become a promising development direction for saving energy and meeting the environment requirements. In this study, based on the mechanical motion equation and the dynamic ATV equation, the electromechanical coupling model of the track vehicles is established by coupling the motor equation. The typical mechanical and electrical parameters in the ATV steering process are measured and compared with the numerical results to verify the correctness of the electromechanical coupling model. Experimental results indicate the main mechanical and electrical parameters of the ATV electro-mechanical system are changed at different articulated point deflection angles. The characteristic parameters of ATV include the change in current and voltage, the size of trajectory radius and the change of power under different deflection angles (10°, 15°, 20°, 25° and 30°), all of which are of great significance for the control of ATV. The current and voltage signals of ATV under specific trajectory can be calculated in reverse by the model, thereby providing a theoretical basis for the trajectory control of articulated vehicles. Therefore, this study provides a reference for the theoretical analysis of electromechanical performance, road driving performance and vehicle design of the electric ATV.

Identification of novel reference genes using sika deer antler transcriptome expression data and their validation for quantitative gene expression analysis

Meichen Liu,Yu Zhao,Baojin Yao,Hui Zhang,Huanyu Guo,Dongyang Hu,Qun Wang 한국유전학회 2014 Genes & Genomics Vol.36 No.5

The most commonly used normalization strategyfor quantitative real-time reverse transcription-polymerasechain reaction (RT-qPCR) is to select a stablereference gene. However, to date, no suitable referencegenes have been identified in sika deer antler tissues. Thus,the aim of this study was to identify the most stable gene ora set of genes to be used as reference genes for RT-qPCRanalysis in sika deer antler tissues. We first selected candidatereference genes using sika deer antler gene expressiondata from an Illumina sequencing platform (Hiseq2000); twenty-one reference genes from the antler tips ofChinese sika deer were selected to test for the normalizationof expression levels during different growth stages. These genes were tested by RT-qPCR and ranked accordingto the stability of their expression using two differentmethods (implemented in geNorm and NormFinder). Based on different algorithms and analytical procedures,our results clearly indicate RPL40 and Gpx as the moststable reference genes of our pool.