SiC IGBT degradation mechanism investigation under HV‑H3TRB tests

Ziming Wu,Zongbei Dai,Jian Zhou,Huafeng Dong,Wencan Wang,Feiwan Xie,Haoran Wang,Jiahui Yan,Xiyu Chen,Shaohua Yang,Fugen Wu 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.2

The high voltage-high humidity-high temperature reverse bias (HV-H3TRB) test was utilized to evaluate the reliability of silicon carbide insulated gate bipolar transistors (SiC IGBTs). Moisture invasion often induces termination/passivation and metal corrosion. Therefore, the HV-H3TRB test is generally used to assess termination / passivation robustness. However, under the HV-H3TRB test conditions, gate quality degradation may occur. In this study, the dominant degradation mechanism of SiC IGBTs was investigated. The changes of the most sensitive static characteristics (e.g., threshold voltage, breakdown voltage, and leakage current) were recorded. The threshold voltage decreased and leakage current increased substantially after > 1000 h of HV-H3TRB tests under 85 ℃/85% RH climate conditions. Capacitance-voltage (C-V) curve measurements indicated that the mobile ions at the SiC/SiO2 interface or in the gate oxide likely caused the threshold-voltage instability in the SiC IGBTs after the HV-H3TRB tests. This instability can be recovered by applying a negative gate bias. Subsequent failure analysis confirmed no corrosion of metals or termination/passivation in the device, which indicates the robustness of the passivation (consisting of phosphor-silicate glass and Si3N4). Therefore, the gate quality appears to be a significant reliability risk for SiC IGBTs under high humidity, high temperature, and high voltage conditions.

STRONG CONVERGENCE THEOREMS OF COMMON ELEMENTS FOR EQUILIBRIUM PROBLEMS AND FIXED POINT PROBLEMS IN BANACH SPACES

Ziming Wang,Yongfu Su 한국전산응용수학회 2010 Journal of applied mathematics & informatics Vol.28 No.3

We introduce a new iterative algorithm for equilibrium and fixed point problems of three hemi-relatively nonexpansive mappings by the CQ hybrid method in Banach spaces, Our results improve and extend the corresponding results announced by Xiaolong Qin, Yeol Je Cho, Shin Min Kang [Xiaolong Qin, Yeol Je Cho, Shin Min Kang, Convergence theorems of common elements for equilibrium problems and fixed point problems in Banach spaces, Journal of Computational and Applied Mathematics 225(2009) 20-30], P. Kumam, K. Wattanawitoon [P. Kumam, K. Wattanawitoon, Convergence theorems of a hybrid algorithm for equilibrium problems, Nonlinear Analysis: Hybrid Systems (2009),doi:10.1016/j.nahs.2009.02.006], W. Takahashi, K. Zembayashi [W. Takahashi, K. Zembayashi, Strong convergence theorem by a new hybrid method for equilibrium problems and relatively nonexpansive mappings, Fixed Point Theory Appl. (2008) doi:10.1155 /2008/528476]and others therein.

STRONG CONVERGENCE THEOREMS OF COMMON ELEMENTS FOR EQUILIBRIUM PROBLEMS AND FIXED POINT PROBLEMS IN BANACH SPACES

Wang, Ziming,Su, Yongfu The Korean Society for Computational and Applied M 2010 Journal of applied mathematics & informatics Vol.28 No.3

We introduce a new iterative algorithm for equilibrium and fixed point problems of three hemi-relatively nonexpansive mappings by the CQ hybrid method in Banach spaces, Our results improve and extend the corresponding results announced by Xiaolong Qin, Yeol Je Cho, Shin Min Kang [Xiaolong Qin, Yeol Je Cho, Shin Min Kang, Convergence theorems of common elements for equilibrium problems and fixed point problems in Banach spaces, Journal of Computational and Applied Mathematics 225 (2009) 20-30], P. Kumam, K. Wattanawitoon [P. Kumam, K. Wattanawitoon, Convergence theorems of a hybrid algorithm for equilibrium problems, Nonlinear Analysis: Hybrid Systems (2009), doi:10.1016/j.nahs.2009.02.006], W. Takahashi, K. Zembayashi [W. Takahashi, K. Zembayashi, Strong convergence theorem by a new hybrid method for equilibrium problems and relatively nonexpansive mappings, Fixed Point Theory Appl. (2008) doi:10.1155/2008/528476] and others therein.

Rapid construction delivery of COVID-19 special hospital: Case study on Wuhan Huoshenshan hospital

Wang, Chen,Yu, Liangcheng,Kassem, Mukhtar A.,Li, Heng,Wang, Ziming Techno-Press 2022 Advances in computational design Vol.7 No.4

Infectious disease emergency hospitals are usually temporarily built during the pneumonia epidemic with higher requirements regarding diagnosis and treatment efficiency, hygiene and safety, and infection control.This study aims to identify how the Building Information Modeling (BIM) + Industrialized Building System (IBS) approach could rapidly deliver an infectious disease hospital and develop site epidemic spreading algorithms. Coronavirus-19 pneumonia construction site spreading algorithm model mind map and block diagram of the construction site epidemic spreading algorithm model were developed. BIM+IBS approach could maximize the repetition of reinforced components and reduce the number of particular components. Huoshenshan Hospital adopted IBS and BIM in the construction, which reduced the workload of on-site operations and avoided later rectification. BIM+IBS integrated information on building materials, building planning, building participants, and construction machinery, and realized construction visualization control and parametric design. The delivery of Huoshenshan Hospital was during the most critical period of the Coronavirus-19 pneumonia epidemic. The development of a construction site epidemic spreading algorithm provided theoretical and numerical support for prevention. The agent-based analysis on hospital evacuation observed "arched" congestion formed at the evacuation exit, indicating behavioral blindness caused by fear in emergencies.

AN ITERATIVE SCHEME FOR EQUILIBRIUM PROBLEMS AND FIXED POINT PROBLEMS OF ASYMPTOTICALLY k-STRICT PSEUDO-CONTRACTIVE MAPPINGS

Wang, Ziming,Su, Yongfu Korean Mathematical Society 2010 대한수학회논문집 Vol.25 No.1

In this paper, we propose an iterative scheme for finding a common element of the set of solutions of an equilibrium problem and the set of fixed points of an asymptotically k-strict pseudo-contractive mapping in the setting of real Hilbert spaces. We establish some weak and strong convergence theorems of the sequences generated by our proposed scheme. Our results are more general than the known results which are given by many authors. In particular, necessary and sufficient conditions for strong convergence of our iterative scheme are obtained.

Information Extraction of Rock Mass structure in Complex Bedrock Mountain Area Based on UAV Oblique Photogrammetry

( Fengyan Wang ),( Mingyu Zhao ),( Fujun Zhou ),( Kai Zhou ),( Qing Ding ),( Ziming Wang ),( Jianping Chen ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

As a new technology developed in recent years, the UAV oblique photogrammetry is of long-distance, non-contact, high-precision and high-density to acquire rapidly 3D spatial data of the object, which has been applied in geological surveying and mapping. Taking the discontinuity information acquisition from Changdu to Linzhi section of Sichuan-Tibet railway in China as an example, 3D model of the survey area is reconstructed by UAV oblique photogrammetry, and the discontinuities are identified and measured in the model by using the 3D mapping system-EPS. Combined with the solution models of discontinuity parameters, the trace length, orientation and opening degree are calculated. Furthermore, the probability distribution of trace length, the dominant grouping of orientation are obtained by probability theory and mathematical statistics. Also, the model display diagram of 3D trace line for long discontinuities, the pole point diagram of orientation, the rose diagram of joint direction and other related maps are drawn by computer graphics so as to describe and cognize the spatial characteristic of complex rock mass structure, which can provide the basic data for stability evaluation of lithological slope and following railway design. The research shows that UAV oblique photogrammetry technology can be applied in discontinuity information extraction of the complex bedrock mountain area compared with the traditional manual measurement, reduces physical input and personal risk, and improve the precision and efficiency of survey, which has a broad application prospects.

Uncovering the Face of Android Ransomware: Characterization and Real-Time Detection

Chen, Jing,Wang, Chiheng,Zhao, Ziming,Chen, Kai,Du, Ruiying,Ahn, Gail-Joon IEEE 2018 IEEE transactions on information forensics and sec Vol.13 No.5

<P>In recent years, we witnessed a drastic increase of ransomware, especially on popular mobile platforms including Android. Ransomware extorts victims for a sum of money by taking control of their devices or files. In light of their rapid growth, there is a pressing need to develop effective countermeasure solutions. However, the research community is still constrained by the lack of a comprehensive data set, and there exists no insightful understanding of mobile ransomware in the wild. In this paper, we focus on the Android platform and aim to characterize existing Android ransomware. Specifically, we have managed to collect 2,721 ransomware samples that cover the majority of existing Android ransomware families. Based on these samples, we systematically characterize them from several aspects, including timeline and malicious features. In addition, the detection results of existing anti-virus tools are rather disappointing, which clearly calls for customized anti-mobile-ransomware solutions. To detect ransomware that extorts users by encrypting data, we propose a novel real-time detection system, called RansomProber. By analyzing the user interface widgets of related activities and the coordinates of users’ finger movements, RansomProber can infer whether the file encryption operations are initiated by users. The experimental results show that RansomProber can effectively detect encrypting ransomware with high accuracy and acceptable runtime performance.</P>

Prediction of the Amount of Soil Discharged by an Earth Pressure Balanced Shield Machine Based on Feature Engineering

Zhu Wen,Zhen Wang,Xuening Rong,Xiaoli Rong,Ziming Xiong,Baohuai Yang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.12

The ground loss caused by earth pressure balance (EPB) shield tunneling is a serious threat to the safety of ground and underground buildings. The amount of soil discharged is a direct factor causing the ground loss, but the feedback of the amount of soil discharged has the problems of human subjectivity and information lag. Based on the theory of soil discharged and shield construction data, a data model for predicting the amount of soil discharged is constructed, and a predictive method of soil discharged based on adaptive adjustment strategy and parameters to achieve optimal regression is proposed. Taking Changzhou shield tunnel construction project as an example, through comparative analysis, the main influencing factors of soil discharge data model are screw-conveyor torque, screw-conveyor revolutions, total thrust, screw-conveyor entrance earth pressure, the revised standard penetration test blow-count, and compression modulus. The results show that the mean absolute error (MAE) of the model is 0.911 m3, and the mean absolute percentage error (MAPE) is 2.78%, which verifies the effectiveness of the prediction of soil discharged by feature engineering.

RBPJ contributes to acquired docetaxel resistance in prostate cancer cells

Li Xue,Zhenlong Wang,Hecheng Li,Zhaolun Li,Qi Chen,Peng Zhang,Haiwen Chen,Ziming Wang,Tie Chong,T. Chong 대한독성 유전단백체 학회 2017 Molecular & cellular toxicology Vol.13 No.3

Our previous work has shown that depletion of recombination signal-binding protein J (RBPJ) results in reduced cell growth in prostate cancer cells. In this study, we aimed to investigate the function of RBPJ in the chemoresistance of prostate cancer. The expression of RBPJ was quantified in docetaxel-resistant and parental prostate cancer cells. Loss- and gainof- function experiments were conducted to explore the regulatory role of RBPJ in prostate cancer sensitivity to docetaxel. The pro-apoptotic effect of RBPJ silencing was checked in docetaxel-resistant prostate cancer cells. We found that docetaxel-resistant PC3-DR and DU145- DR cells expressed 3-5-fold high levels of RBPJ than parental PC3 and DU145 cells. Short hairpin RNAmediated knockdown of RBPJ inhibited cell proliferation and colony formation and reversed docetaxel resistance in docetaxel-resistant prostate cancer cells. In contrast, overexpression of RBPJ promoted cell growth, colony formation, and docetaxel resistance in parental prostate cancer cells. Downregulation of RBPJ induced apoptosis in docetaxel-resistant cells, which was accompanied by enhanced cleavage of caspase-3. In addition, RBPJ silencing or overexpression markedly modulated the expression of the Bcl-2 family members including Bcl-2, Bcl-xL, Mcl-1, Bax, and Bak. Altogether, RBPJ contributes to acquisition of docetaxel resistance in prostate cancer cells and may thus represent a potential target for overcoming chemotherapeutic resistance in this malignancy.

A Fast Estimation Method of Soil Discharged by an Earth Pressure Balanced Shield Machine

Zhu Wen,Xuening Rong,Zhen Wang,Songtong Han,Ziming Xiong,Yehui Shi 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.6

The soil discharged by an earth pressure balanced (EPB) shield machine reflects ground loss and controls surface settlement. In engineering, the discharge was mainly estimated by weighing the tunnelling spoil, however, human disturbance and information lag bring serious hidden security risks to tunnel construction. Through the analysis of conveying flow and force of screw conveyor, an energy model of interaction between screw conveyor and soil discharged was proposed and verified experimentally. Then, the energy model was combined with the discharge equation and the force balance equation, and a semi-analytical method to fast estimate the soil discharged of the EPB shield machine was proposed. Taking an EPB shield construction project as an example, according to the data of earth pressure, the torque and the rotation of the screw conveyor recorded by EPB shield machine, the real-time soil discharged of EPB shield machine can be accurately estimated. The mean absolute error (MAE) of this method is 3.177 × 103 kg compared with the measured weight of tunnelling spoil, which verifies the rationality of the method and provides a method for further effective evaluation and control of ground loss.