Dynamic Recrystallization and Grain Refinement in Extruded AZ31 Rod During Hot Torsion Deformation at 150 °C

Hongbing Chen,Bo Song,Ning Guo,Tingting Liu,Tao Zhou,Jiejun He 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.1

The dynamic recrystallization mechanism and microstructure evolution in an extruded AZ31 rod during hot torsion deformationat 150 °C were investigated. It indicated that several dynamic recrystallization mechanisms were initiated during hottorsion deformation, including discontinuous DRX (DDRX), continuous DRX (CDRX) and twinning induced DRX (TDRX). With increasing strain, CDRX became the dominant DRX mechanism and contributed to a remarkable refinement of grains. A gradient distribution of dynamic recrystallization grains on the cross section of samples generated due to the gradientshear strain in twisted samples. Hot torsion can also arouse the c-axis of grains to rotate towards the extrusion direction. From low strain to high strain, the recrystallized grains exhibited a similar texture development with the deformed grains. The relevant mechanisms were revealed.

DroidVecDeep: Android Malware Detection Based on Word2Vec and Deep Belief Network

( Tieming Chen ),( Qingyu Mao ),( Mingqi Lv ),( Hongbing Cheng ),( Yinglong Li ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.4

With the proliferation of the Android malicious applications, malware becomes more capable of hiding or confusing its malicious intent through the use of code obfuscation, which has significantly weaken the effectiveness of the conventional defense mechanisms. Therefore, in order to effectively detect unknown malicious applications on the Android platform, we propose DroidVecDeep, an Android malware detection method using deep learning technique. First, we extract various features and rank them using Mean Decrease Impurity. Second, we transform the features into compact vectors based on word2vec. Finally, we train the classifier based on deep learning model. A comprehensive experimental study on a real sample collection was performed to compare various malware detection approaches. Experimental results demonstrate that the proposed method outperforms other Android malware detection techniques.

Few-Layered MoS2 Nanoparticles Loaded TiO2 Nanosheets with Exposed {001} Facets for Enhanced Photocatalytic Activity

Chujun Chen,Xia Xin,Jinniu Zhang,Gang Li,Yafeng Zhang,Hongbing Lu,Jianzhi Gao,Zhibo Yang,Chunlan Wang,Ze He 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.11

To improve the high charge carrier recombination rate and low visible light absorption of {001} facets exposed TiO2 [TiO2(001)] nanosheets, few-layered MoS2 nanoparticles were loaded on the surfaces of TiO2(001) nanosheets by a simple photodeposition method. The photocatalytic activities towards Rhodamine B (RhB) were investigated. The results showed that the MoS2–TiO2(001) nanocomposites exhibited much enhanced photocatalytic activities compared with the pure TiO2(001) nanosheets. At an optimal Mo/Ti molar ratio of 25%, the MoS2–TiO2(001) nanocomposites displayed the highest photocatalytic activity, which took only 30 min to degrade 50mL of RhB (50 mg/L). The active species in the degradation reaction were determined to be hþ and OH according to the free radical trapping experiments. The reduced charge carrier recombination rate, enhanced visible light utilization and increased surface areas contributed to the enhanced photocatalytic performances of the 25% MoS2–TiO2(001) nanocomposites.

Three-dimensionally Hierarchical Bi2WO6 Architectures with Enhanced Photocatalytic Activity

Tianhua Chen,Hongbing Lu,Jinniu Zhang,Jianzhi Gao,Feng Yin,Zhibo Yang,Qianru Liu,Xuewei Zhang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.12

Three-dimensionally hierarchical Bi2WO6 architectures have been produced via a facile and economical hydrothermal method without any template or surfactant. This architecture with flower-like morphology is assembled by numbers of intercrossed nanosheets. Moreover, different Bi2WO6 nanostructures including multilayered disks and irregular nanoplates can also be produced by simply adjusting the pH value of the precursor solution. Importantly, this kind of hierarchically structured Bi2WO6 architecture exhibits a much better photocatalytic activity in the photodegradation of rhodamine B than that of conventional Bi2WO6 multilayered disks and nanoplates. This enhanced photocatalytic performance is mainly attributed to the large specific surface areas, special structural features and high capability of absorbed oxygen species. The present work offers an effective approach for the further improvement of photocatalytic activity by designing a desirable micro/nanoarchitecture.

Experimental study on steel-concrete composite beams with Uplift-restricted and slip-permitted screw-type (URSP-S) connectors

Linli Duan,Hongbing Chen,Xin Nie,Sanwei Han 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.2

In steel-concrete composite beams, to improve the cracking resistance of the concrete slab in the hogging moment region, a new type of connector in the interface, named uplift-restricted and slip-permitted screw-type (URSP-S) connector has been proposed. This paper focuses on the behavior of steel-concrete composite beams with URSP-S connectors. A total of three beam specimens including a simply supported beam with URSP-S connectors and two continuous composite beams with different connectors arrangements were designed and tested. More specifically, one continuous composite beam was equipped with URSP-S connectors in negative moment region and traditional shear studs in other regions. For comparison, the other one was designed with only traditional shear studs. The failure modes, crack evolution process, ultimate capacities, strain responses at different locations as well as the interface slip of the three tested specimens were measured and evaluated in-depth. Based on the experimental study, the research findings indicate that the larger slip deformation is allowed while using URSP-S connectors. Meanwhile, the tensile stress reduces and the cracking resistance of the concrete slab improves accordingly. In addition, the overall stiffness and strength of the composite beam become slightly lower than those of the composite beam using traditional shear studs. Moreover, the arrangement suggestion of URSP-S connectors in the composite beam is discussed in this paper for its practical design and application.

A Comparison of Transradial and Transfemoral Percutaneous Coronary Intervention in Chinese Women Based on a Propensity Score Analysis

Yi Xu,Chen Jin,Shubin Qiao,Yongjian Wu,Hongbing Yan,Kefei Dou,Bo Xu,Jingang Yang,Yuejin Yang 대한심장학회 2018 Korean Circulation Journal Vol.48 No.8

Background and Objectives: Over the past decades, transradial approach for percutaneous coronary intervention (PCI) has been increasingly adopted in clinical practice. Women represent a large population who will possibly benefit from PCI, but they are often under-represented in clinical studies. Therefore, the role of TRI in women remains to be further defined. This study sought to compare safety and efficacy for transradial intervention (TRI) and transfemoral intervention (TFI) in women undergoing PCI in China. Methods: The study population consisted of 5,067 women undergoing PCI at Fuwai Hospital, Beijing, China between 2006 and 2011 (TRI: n=4,105, TFI: n=962). Incidence rates of clinical outcomes during hospitalization and at 1-year follow-up were compared between TRI and TFI. In order to minimize potential biases, a 1:1 propensity score matching (PSM) was performed. A total of 899 pairs were matched. Results: Baseline and procedural characteristics were well-balanced between TRI and TFI groups after controlling for confounders using PSM. TRI was associated with reduced major post-PCI bleeding (odds ratio [OR], 0.64; 95% confidence interval [CI], 0.54–0.76; p<0.001) and access site complications (OR, 0.67; 95% CI, 0.61–0.74; p<0.001) after PSM. There was no statistical differences in the incidence rates of major adverse cardiac events (a composite of cardiac death, myocardial infarction, and target vessel revascularization) both during hospitalization and at 1-year follow-up (p>0.05). Conclusions: In this propensity score-based analysis of TRI versus TFI in Chinese women, TRI showed advantages of safety and feasibility over TFI. A wider adoption of TRI in women has the potential to improve outcomes in treatment of coronary artery diseases.

Wave propagation simulation and its wavelet package analysis for debonding detection of circular CFST members

Bin Xu,Hongbing Chen,Song Xia 국제구조공학회 2017 Smart Structures and Systems, An International Jou Vol.19 No.2

In order to investigate the interface debonding defects detection mechanism between steel tube and concrete core of concrete-filled steel tubes (CFSTs), multi-physical fields coupling finite element models constituted of a surface mounted Piezoceramic Lead Zirconate Titanate (PZT) actuator, an embedded PZT sensor and a circular cross section of CFST column are established. The stress wave initiation and propagation induced by the PZT actuator under sinusoidal and sweep frequency excitations are simulated with a two dimensional (2D) plain strain analysis and the difference of stress wave fields close to the interface debonding defect and within the cross section of the CFST members without and with debonding defects are compared in time domain. The linearity and stability of the embedded PZT response under sinusoidal signals with different frequencies and amplitudes are validated. The relationship between the amplitudes of stress wave and the measurement distances in a healthy CFST cross section is also studied. Meanwhile, the responses of PZT sensor under both sinusoidal and sweep frequency excitations are compared and the influence of debonding defect depth and length on the output voltage is also illustrated. The results show the output voltage signal amplitude and head wave arriving time are affected significantly by debonding defects. Moreover, the measurement of PZT sensor is sensitive to the initiation of interface debonding defects. Furthermore, wavelet packet analysis on the voltage signal under sweep frequency excitations is carried out and a normalized wavelet packet energy index (NWPEI) is defined to identify the interfacial debonding. The value of NWPEI attenuates with the increase in the dimension of debonding defects. The results help understand the debonding defects detection mechanism for circular CFST members with PZT technique.

Excellent Strengthening of Low-Carbon Steel by Severe Free-End Torsion

Shijun Tan,Bo Song,Hongbing Chen,Xiaodong Tan,Risheng Qiu,Tingting Liu,Ning Guo,Shengfeng Guo 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.8

In this work, the effects of free-end torsion on microstructure and tensile property of low-carbon steel were investigated indetail. Low-carbon steels exhibited exceptionally high yield strength through severe torsion deformation. Such high hardeningeffect was mainly attributed to the severe lattice distortion, high density of dislocations and the change in grain shape. Moreover, a gradient deformation structure can be introduced by torsion deformation. The gradient-structure can generate ahigh hetero-deformation induced strengthening, which can increase the strain hardening capacity and remain high plasticity/toughness. Therefore, with increasing torsion angle from 700 to 2800 deg., the uniform elongation and the peak strength werelargely enhanced. After twisting 2800 deg., yield strength and peak strength can achieve 524 MPa and 675 MPa, respectively,and good tensile elongations (εf = 9.6%, εu = 7.4%) are remained.

Family History of Cancer and Head and Neck Cancer Risk in a Chinese Population

Huang, Yu-Hui Jenny,Lee, Yuan-Chin Amy,Li, Qian,Chen, Chien-Jen,Hsu, Wan-Lun,Lou, Pen-Jen,Zhu, Cairong,Pan, Jian,Shen, Hongbing,Ma, Hongxia,Cai, Lin,He, Baochang,Wang, Yu,Zhou, Xiaoyan,Ji, Qinghai,Zho Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.17

Background: The aim of this study was to investigate whether family history of cancer is associated with head and neck cancer risk in a Chinese population. Materials and Methods: This case-control study included 921 cases and 806 controls. Recruitment was from December 2010 to January 2015 in eight centers in East Asia. Controls were matched to cases with reference to sex, 5-year age group, ethnicity, and residence area at each of the centers. Results: We observed an increased risk of head and neck cancer due to first degree family history of head and neck cancer, but after adjustment for tobacco smoking, alcohol drinking and betel quid chewing the association was no longer apparent. The adjusted OR were 1.10 (95% CI=0.80-1.50) for family history of tobacco-related cancer and 0.96 (95%CI=0.75-1.24) for family history of any cancer with adjustment for tobacco, betel quid and alcohol habits. The ORs for having a first-degree relative with HNC were higher in all tobacco/alcohol subgroups. Conclusions: We did not observe a strong association between family history of head and neck cancer and head and neck cancer risk after taking into account lifestyle factors. Our study suggests that an increased risk due to family history of head and neck cancer may be due to shared risk factors. Further studies may be needed to assess the lifestyle factors of the relatives.

Preparation and Characterization of Mg Alloy Rods with Gradient Microstructure by Torsion Deformation

Bo Song,Huaizhi Zhao,Linjiang Chai,Ning Guo,Hucheng Pan,Hongbing Chen,Renlong Xin 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.5

Extruded AZ31 Mg alloy rods were subject to free-end torsion deformation at room temperature. The microstructure features of the torsion deformed samples were characterized using electron backscatter diffraction technique. Mg rods with gradient microstructure can be fabricated by torsion deformation. Inhomogeneous distribution of microstructure along the radial direction of the twisted rods is attributed to the linearly increasing strain accumulation and strain rate from core to surface. With increasing equivalent strain, both the amount of {10- 12} twins and dislocation density increase and the c-axes of texture tend to rotate towards torsion axis. Although both dislocation slips and {10-12} twinning can be activated during torsion, dislocation slips are considered as the dominated deformation mechanism and responsible for the change of macro-texture for present torsion deformation. {10-12} twins and dislocations in the twisted samples can generate refinement hardening and dislocation hardening, respectively, to increase the hardness value.