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.

Space-Time Quantization and Motion-Aligned Reconstruction for Block-Based Compressive Video Sensing

( Ran Li ),( Hongbing Liu ),( Wei He ),( Xingpo Ma ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.1

The Compressive Video Sensing (CVS) is a useful technology for wireless systems requiring simple encoders but handling more complex decoders, and its rate-distortion performance is highly affected by the quantization of measurements and reconstruction of video frame, which motivates us to presents the Space-Time Quantization (ST-Q) and Motion-Aligned Reconstruction (MA-R) in this paper to both improve the performance of CVS system. The ST-Q removes the space-time redundancy in the measurement vector to reduce the amount of bits required to encode the video frame, and it also guarantees a low quantization error due to the fact that the high frequency of small values close to zero in the predictive residuals limits the intensity of quantizing noise. The MA-R constructs the Multi-Hypothesis (MH) matrix by selecting the temporal neighbors along the motion trajectory of current to-be-reconstructed block to improve the accuracy of prediction, and besides it reduces the computational complexity of motion estimation by the extraction of static area and 3-D Recursive Search (3DRS). Extensive experiments validate that the significant improvements is achieved by ST-Q in the rate-distortion as compared with the existing quantization methods, and the MA-R improves both the objective and the subjective quality of the reconstructed video frame. Combined with ST-Q and MA-R, the CVS system obtains a significant rate-distortion performance gain when compared with the existing CS-based video codecs.

Joint wireless and computational resource allocation for ultra-dense mobile-edge computing networks

( Junyi Liu ),( Hongbing Huang ),( Yijun Zhong ),( Jiale He ),( Tiancong Huang ),( Qian Xiao ),( Weiheng Jiang ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.7

In this paper, we study the joint radio and computational resource allocation in the ultra-dense mobile-edge computing networks. In which, the scenario which including both computation offloading and communication service is discussed. That is, some mobile users ask for computation offloading, while the others ask for communication with the minimum communication rate requirements. We formulate the problem as a joint channel assignment, power control and computational resource allocation to minimize the offloading cost of computing offloading, with the precondition that the transmission rate of communication nodes are satisfied. Since the formulated problem is a mixed-integer nonlinear programming (MINLP), which is NP-hard. By leveraging the particular mathematical structure of the problem, i.e., the computational resource allocation variable is independent with other variables in the objective function and constraints, and then the original problem is decomposed into a computational resource allocation subproblem and a joint channel assignment and power allocation subproblem. Since the former is a convex programming, the KKT (Karush-Kuhn-Tucker) conditions can be used to find the closed optimal solution. For the latter, which is still NP-hard, is further decomposed into two subproblems, i.e., the power allocation and the channel assignment, to optimize alternatively. Finally, two heuristic algorithms are proposed, i.e., the Co-channel Equal Power allocation algorithm (CEP) and the Enhanced CEP (ECEP) algorithm to obtain the suboptimal solutions. Numerical results are presented at last to verify the performance of the proposed algorithms.

Oxygen vacancies – Cu doping junction control of d-Bi2O3 nanosheets for enhanced photocatalytic nitrogen fixation

Xiaoming Gao,Kaixuan Xu,Hongbing He,Shouda Liu,Xiangbo Zhao 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.111 No.-

Cu-d-Bi2O3 nanosheets with uniform thickness of approximately 2.7 nm and length about 200 nm forphotocatalytic nitrogen fixation and photocatalytic oxidation is achieved by simple hydrothermalmethod. The 2D ultrathin structure is benefit to the formation of the surface oxygen vacancies, meanwhilethe impurity defect is formed due to the substitutive Cu doping of d-Bi2O3. The as-prepared 5%Cu-d-Bi2O3 exhibits excellent NH4 + generation rate of 142.8 lmol h1 g1 without any sacrificial agentirradiated by visible light. The remarkable photocatalytic ability can be attributed to the ultrafast carrierstransfer from the interior to the surface because of 2D ultrathin structure feature, the separation ofelectrons-holes and molecular chemisorption due to the formation of surface oxygen vacancies andimpurity defect.

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.

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.