Numerical junction temperature calculation method for reliability evaluation of power semiconductors in power electronics converters

Du, Xiao,Du, Xiong,Zhang, Jun,Li, Gaoxian The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

The junction temperature of power semiconductors is a critical parameter during reliability evaluation. The incorporation of long-term mission profiles, such as power loadings and ambient temperature, into lifetime and reliability evaluations of power semiconductors increases the computational burden. Thus, there is an urgent need for a more accurate method for junction temperature acquisition. Current methods for junction temperature calculation are computationally inefficient and do not comprehensively incorporate long-term factors into junction temperature calculation and power semiconductor reliability evaluation. Here, a junction temperature calculation method is proposed that enables reliability evaluation for insulated gate bipolar transistor (IGBT) power semiconductors. This approach calculates the IGBT module junction temperature on the basis of an electro-thermal analogy using Gauss-Seidel iteration. When compared with electrical-thermal simulation and other numerical calculation methods, the proposed method guarantees accuracy, while greatly reducing the computational time and load. A performance comparison between the proposed method, electro-thermal simulation based on a Fuji IGBT simulator, and experimental results was carried out using a three-phase DC/AC inverter as a case study.

Single-cell RNA sequencing reveals B cell–related molecular biomarkers for Alzheimer’s disease

Xiong Liu-Lin,Xue Lu-Lu,Du Ruo-Lan,Niu Rui-Ze,Chen Li,Chen Jie,Hu Qiao,Tan Ya-Xin,Shang Hui-Fang,Liu Jia,Yu Chang-Yin,Wang Ting-Hua 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-

In recent years, biomarkers have been integrated into the diagnostic process and have become increasingly indispensable for obtaining knowledge of the neurodegenerative processes in Alzheimer’s disease (AD). Peripheral blood mononuclear cells (PBMCs) in human blood have been reported to participate in a variety of neurodegenerative activities. Here, a single-cell RNA sequencing analysis of PBMCs from 4 AD patients (2 in the early stage, 2 in the late stage) and 2 normal controls was performed to explore the differential cell subpopulations in PBMCs of AD patients. A significant decrease in B cells was detected in the blood of AD patients. Furthermore, we further examined PBMCs from 43 AD patients and 41 normal subjects by fluorescence activated cell sorting (FACS), and combined with correlation analysis, we found that the reduction in B cells was closely correlated with the patients’ Clinical Dementia Rating (CDR) scores. To confirm the role of B cells in AD progression, functional experiments were performed in early-stage AD mice in which fibrous plaques were beginning to appear; the results demonstrated that B cell depletion in the early stage of AD markedly accelerated and aggravated cognitive dysfunction and augmented the Aβ burden in AD mice. Importantly, the experiments revealed 18 genes that were specifically upregulated and 7 genes that were specifically downregulated in B cells as the disease progressed, and several of these genes exhibited close correlation with AD. These findings identified possible B cell-based AD severity, which are anticipated to be conducive to the clinical identification of AD progression.

Facile Fabrication of Quaternary Ammonium Salt Modified Cotton Linter by Radiation Grafting and its Effective Removal of Methyl Orange: Batch and Dynamic Flow Mode Studies

Jifu Du,Manman Zhang,Zhen Dong,Xin Yang,Houhua Xiong,Zhengkui Zeng,Zhiyuan Chen,Long Zhao 한국섬유공학회 2022 Fibers and polymers Vol.23 No.4

Methyl orange plays a vital role in various branches of the dyeing and textile industries and must be treated beforebeing discharged into the environment. In this study, methacryloxyethyltrimethyl ammonium chloride (DMC) functionalizedcotton linter (DMCCL) was prepared using a radiation technique. The prepared DMCCL was then characterized by IR, SEM,TG, and XPS analyses. The results showed that DMC was successfully grafted onto the surface of the cotton linter. Theadsorption performance toward methyl orange (MO) was investigated using batch and fix-bed column experiments. Adsorption kinetic and isotherm studies were well described by pseudo-second-order kinetic and Langmuir isotherm model,respectively. The maximum adsorption capacity for MO was 645.16 mg/g. The fixed-bed column experiment showed thatThomas and Yoon-Nelson models described the experimental data well. The column study showed the adsorption capacityreached 564.46 mg/g with a MO concentration of 25 mg/l and flow rate 1.5 ml/min. The saturated DMCCL column could beregenerated efficiently by eluting with 1 M HCl. Therefore, the DMCCL exhibited excellent adsorption performance, whichis suitable for MO removal from aqueous solution.

Friction Characteristics of a Cylinder Based on a Bridge-Type Pneumatic Energy-saving Circuit

Hongwang Du,Wei Xiong,Zhong’ai Jiang,Qiu Li,Lu Wang 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.1

A bridge-type energy-saving circuit is a new type of pneumatic system that uses four on-off valves tocontrol the inlet and exhaust of two cylinder chambers. It saves energy through the open-and-close sequence of thefour control valves. Cylinder friction is the key factor in accuracy and stability of the bridge-type pneumatic energysavingcircuit. This paper focuses on research of the circuit’s friction characteristics. Based on friction theory andthe classic Stribeck model, a composite dynamic friction model of a cylinder in a circuit system is established, anda cylinder friction test platform is constructed. The Nelder-Mead algorithm is used to identify static parametersof the model through the relationship between friction and velocity while the piston is moving. Friction modelverification with error analysis is achieved by comparison with the traditional friction model. Experiments withthe energy-saving circuit under certain conditions are carried out to illustrate the effectiveness of the compositedynamic friction model. Finally, compared with existing friction model, the validity of the model is proved to beapplicable to different working conditions.

Outage Analysis and Optimization for Time Switching-based Two-Way Relaying with Energy Harvesting Relay Node

( Guanyao Du ),( Ke Xiong ),( Yu Zhang ),( Zhengding Qiu ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.2

Energy harvesting (EH) and network coding (NC) have emerged as two promising technologies for future wireless networks. In this paper, we combine them together in a single system and then present a time switching-based network coding relaying (TSNCR) protocol for the two-way relay system, where an energy constrained relay harvests energy from the transmitted radio frequency (RF) signals from two sources, and then helps the two-way relay information exchange between the two sources with the consumption of the harvested energy. To evaluate the system performance, we derive an explicit expression of the outage probability for the proposed TSNCR protocol. In order to explore the system performance limit, we formulate an optimization problem to minimize the system outage probability. Since the problem is non-convex and cannot be directly solved, we design a genetic algorithm (GA)-based optimization algorithm for it. Numerical results validate our theoretical analysis and show that in such an EH two-way relay system, if NC is applied, the system outage probability can be greatly decreased. Moreover, it is shown that the relay position greatly affects the system performance of TSNCR, where relatively worse outage performance is achieved when the relay is placed in the middle of the two sources. This is the first time to observe such a phenomena in EH two-way relay systems.

Transmission Power Minimization with Network Coding for Mobile Terminals in Cellular Relay Networks

( Guanyao Du ),( Ke Xiong ),( Dandan Li ),( Zhengding Qiu ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.9

This paper jointly investigates the bandwidth allocation, transmission strategy and relay positions for two-way transmission aware cellular networks with network coding (NC). Our goal is to minimize the transmission power of mobile terminals (MTs). Consider a cellular system, where multiple MTs exchange information with their common base station, firstly, we propose an efficient bandwidth allocation method and then give a transmission strategy for each MT to determine whether to use relay stations (RSs) for its two-way transmission with the BS or not. To further improve the system performance, the optimal positions of RSs are also jointly discussed. A GA-based algorithm is presented to obtain the optimum positions for RSs. Besides, the impacts of frequency reuse on MT`s transmission power and system spectral efficiency (SE) under different number of relays are also discussed in our work. Numerical results show that the proposed NC aware scheme can extend MTs` battery life at least 6% more than traditional method.

A Nonlinear Dynamic Optimization Algorithm of a Novel Energy Efficient Pneumatic Drive System

Hongwang Du,Wei Xiong,Wei Liu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.5

A standard pneumatic system is usually controlled by a 5/2 directional control valve in which compressed-air utilization rate is low. To solve the problem, scholars have proposed a bridge pneumatic circuit controlled by four switch valves that uses expansion energy of compressed air to do work. The key to this bridge circuit lies in the accuracy and speed of on-off sequence of the valves. To realize this goal, we study dynamic optimization control of the circuit and establish an optimal valve opening and closing time-sequence control model with a continuous-discrete time differential algebraic equation on the base of the dynamic characteristics of the pneumatic drive system. We use the direct method in modern optimal control theory to solve the problem. Because the model has the characteristics of more equality constraints, lower freedom of variables, and a sparse structure, we use the simplified space sequential quadratic programming algorithm and interior-point methods for computation and analysis so that the process optimization and partial-differential equations are solved simultaneously. To improve the precision and the speed of solving the derivative during the solution-optimization process, the derivative information is obtained with a combination of symbol and numerical automatic differentiation. By analyzing the efficiency of the two algorithms, the interior-point method was proved to be more suitable for use in obtaining the sequence. Finally, the experimental results were realized and showed that our contribution builds a good foundation for the energy-saving research of pneumatic systems.

Experimental Study of the Shear Capacity of Steel Beam-to-L-CFST Column Connections

Qingqing Xiong,Wang Zhang,Zhi-Hua Chen,Yansheng Du,Ting Zhou 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.3

This paper aims to investigate the shear performance of a new and innovative type of vertical stiff ener connection between steel beams and L-shaped columns composed of concrete-fi lled steel tubes connected by transverse and vertical steel plates (L-CFST columns) in high-rise residential buildings. Quasi-static cyclic loading tests were performed on fi ve full-scale specimens to investigate the panel zone behaviours. Based on the experimental results, the hysteretic responses, skeleton curves of the shear force–deformation, ductility, stiff ness degradation, energy dissipation and strain are discussed. The variables studied in these experiments include the joint type, axial compression ratio, cross-sectional area and width-to-thickness ratio of the vertical stiff ener, and presence of concrete. The results indicate that the cross-sectional area of the vertical stiff eners plays a critical role in the performance of the panel zone. Two types of failure modes were observed outside the panel zone: fracturing of the vertical stiff eners and fracturing of the beam fl ange connecting plate. Shear deformation of the panel zone was obvious in the exterior joint specimens, and the corresponding maximum shear deformation reached 0.05 rad. Furthermore, the scopes of the panel zone in the corner and exterior joint specimens were determined by the strain distribution.

Titanium Dioxide–Graphene–Polyaniline Hybrid for Nonenzymatic Detection of Glucose

Jiawen Du,Yiyang Tao,Zhichen Xiong,Xianglang Yu,Aijuan Xie,Shiping Luo,Xiazhang Li,Chao Yao 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.7

A novel titanium dioxide–graphene–polyaniline (TiO2–RGO–PANI) hybrid was prepared by the one-pot method and used as a nonenzymatic electrochemical sensor for glucose detection. The composition and structural morphology of the as-prepared composites were determined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The characterization results showed that TiO2–RGO–PANI is mainly composed of Ti, O, C and N and their weight percentages are 67.68%, 21.57%, 10.70% and 0.05%, respectively, indicating that the TiO2–RGO–PANI composite catalyst has been successfully prepared and presents a poriferous coral structure. A series of electrochemical tests such as cyclic voltammetry tests declared that TiO2–RGO–PANI composite possessed a low limit of detection (LOD) (7.46 μM), good repeatability, selectivity and stability. In the concentration range of 10–180 μM, the hybrid presented linear diffusion, and the linear equation was Ipa = 0.21338 + 0.01392 (C/mM), the correlation coefficient R2 = 0.9912. In addition, the comparison of the merits of this proposed electrode with some recent nonenzymatic glucose sensors indicates that this highly sensitive TiO2–RGO–PANI complex glucose sensor provides a simple, low-cost, nonenzymatic method for glucose detection, and has promising applications in clinical diagnostics and medical analysis.

Identification of HDAC9 as a viable therapeutic target for the treatment of gastric cancer

Kai Xiong,Hejun Zhang,Yang Du,Jie Tian,Shigang Ding 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

Histone deacetylase inhibitors (HDACis) are a new class of anticancer drugs confirmed to have good therapeutic effects against gastric cancer (GC) in preclinical experiments, but most HDACis are non-selective (pan-HDACis), with highly toxic side effects. Therefore, it is necessary to screen HDAC family members that play key roles in GC as therapeutic targets to reduce toxic side effects. In this study, we evaluated the targeting specificity of the HDACi suberoylanilide hydroxamic acid (SAHA) for GC via fluorescence molecular imaging (FMI). In vitro FMI results showed that SAHA had higher binding affinity for GC cells than for normal gastric cells. In vivo FMI of gastric tumor-bearing mice confirmed that SAHA can be enriched in GC tissues. However, there was also a high-concentration distribution in normal organs such as the stomach and lungs, suggesting potential side effects. In addition, we found that among the HDAC family members, HDAC9 was the most significantly upregulated in GC cells, and we verified this upregulation in GC tissues. Further experiments confirmed that knockdown of HDAC9 inhibits cell growth, reduces colony formation, and induces apoptosis and cell cycle arrest. These results suggest that HDAC9 has an oncogenic role in GC. Moreover, HDAC9 siRNA suppressed GC tumor growth and enhanced the antitumor efficacy of cisplatin in GC treatment by inhibiting the proliferation and inducing the apoptosis of GC cells in vitro and in vivo. Our findings suggest that the development of HDAC9-selective HDACis is a potential approach to improve the efficacy of chemotherapy and reduce systemic toxicity.