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Effect of austenitizing condition on mechanical properties,microstructure and precipitation behavior of AISI H13 steel

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Journal of Iron and Steel Research(International) 2024年第1期31卷 143-156页

作者： An-gang Ning Yang Liu Rui gao Stephen yue ming-bo Wang Han-jie Guo College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan030024ShanxiChina Department of Mining and Materials Engineering McGill UniversityMontrealQCH3A 0C5Canada ASSAB Tooling Technology(Chongqing)Co. Ltd.Chongqing401120China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing100083China

The effects of austenitizing temperature(1223,1303,and 1373 K)and holding time(1-1500 s)on the microstructure,mechanical properties,and precipitation behavior of the H13 hot work die steel were investigated.The results indicate a softening phenomenon when H13 steel is austenitized at 1303 K beyond 900 s and 1373 K beyond 600 s,respectively.For the sample held for 1200 s,the tensile strength is found capable of reaching up to 2.2 GPa when quenched from a temperature above 1303 K.Meanwhile,prior-austenite grain size increases with the increase in austenitizing temperature.The kinetic behavior of the precipitates(mainly MC-type carbides)in H13 steel could be elaborated through the principles set forth by the Arrhenius and Avrami equations.Finally,the comprehensive strengthening of the H13 steel was discussed in detail.The results show that the activation energy of the transformed fraction of carbides is higher than that of the diffusion process for common alloying elements(Cr,V,Mo,and Ni)found in the austenite.This suggests that it would be difficult for precipitates to dissolve into the matrix when H13 steel is austenitized at high temperatures.With the increasing austenitizing temperature,the precipitation fraction decreases,and the dislocation density increases.The dislocation strengthening is regarded as the dominant strengthening contributed to yield strength in as-quenched H13 steel.

关键词： H13 steel Austenitizing Mechanical property Precipitation behavior Comprehensive strengthening

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Maternal mental health and well-being during the COVID-19 pandemic in Beijing, China

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World Journal of Pediatrics 2021年第3期17卷 280-289页

作者： Zhuang Wei Ming-Yue Gao Mary Fewtrell Jonathan Wells Jin-yue Yu Department of Child Healthcare Beijing Children’s HospitalCapital Medical UniversityNational Center for Children’s HealthBeijingChina Population Policy and Practice Research and Teaching DepartmentUCL Great Ormond Street Institute of Child Health30 Guilford StreetLondon WC1N 1EHUK

Background The aim of this study is to evaluate the impact of the coronavirus disease 2019(COVID-19)pandemic on breastfeeding women and to identify predictors of maternal mental health and coping.Methods Mothers aged≥18 years with a breast-fed infant≤18 months of age during the COVID-19 pandemic in Beijing,China,completed a questionnaire.Descriptive analysis of lockdown consequences was performed and predictors of these outcomes were examined using stepwise linear regression.Results Of 2233 participants,29.9%,20.0%and 34.7%felt down,lonely,and worried,respectively,during the lockdown;however,85.3%felt able to cope.Poorer maternal mental health was predicted by maternal(younger age,higher education)and infant(older age,lower gestation)characteristics,and social circumstances(husband unemployed or working from home,receiving advice from family,having enough space for the baby,living close to a park or green space).Conversely,better maternal mental health was predicted by higher income,employment requiring higher qualifications,more personal space at home,shopping or walking>once/week and lack of impact of COVID-19 on job or income.Mothers with higher education,more bedrooms,fair division of household chores and attending an online mother and baby group>once/week reported better coping.Conclusion The findings highlight maternal characteristics and circumstances that predict poorer mental health and reduced coping which could be used to target interventions in any future public health emergencies requiring social restrictions.

关键词： Coping Coronavirus disease 2019 Maternal health Mental health Postpartum

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The Lie Conformal Algebra of a Block Type Lie Algebra

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Algebra Colloquium 2015年第3期22卷 367-382页

作者： ming gao Ying Xu Xiaoqing yue Wu Wen-Tsun Key Laboratory of MathematicsUniversity of Science and 3bchnology of China Hefei 230026 China Department of Mathematics Hefei University of Technology Hefei 230009 China Department of Mathematics Tongji University Shanghai 200092 China

Let L be a Lie algebra of Block type over C with basis {Lα,i ｜ a,i ∈ Z} and brackets [Lα,i, Lβ,j] = （β（i ＋ 1） - α（j ＋ 1））Lα＋β,i＋j. In this paper, we first construct a formal distribution Lie algebra of L. Then we decide its conformal algebra B with C[δ]- basis { Lα（w）｜ α ∈ Z} and λ-brackets [Lα（w）λLβ（w）] = （αδ ＋（α ＋β）A）Lα＋β（w）. Finally, we give a classification of free intermediate series B-modules.

关键词： Block type Lie algebras Lie conformal algebras modules over Lie conformal algebras free intermediate series modules

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A Survey of Human Action Recognition and Posture Prediction

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Tsinghua Science and Technology 2022年第6期27卷 973-1001页

作者： Nan Ma Zhixuan Wu Yiu-ming Cheung Yuchen Guo yue gao Jiahong Li Beiyan Jiang Beijing Key Laboratory of Information Service Engineering the College of RoboticsBeijing Union UniversityBeijing 100101China Department of Computer Science Hong Kong Baptist UniversityHong Kong 999077China Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China School of Software Tsinghua UniversityBeijing 100084China College of Robotics Beijing Union UniversityBeijing 100101China

Human action recognition and posture prediction aim to recognize and predict respectively the action and postures of persons in videos.They are both active research topics in computer vision community,which have attracted considerable attention from academia and industry.They are also the precondition for intelligent interaction and human-computer cooperation,and they help the machine perceive the external environment.In the past decade,tremendous progress has been made in the field,especially after the emergence of deep learning technologies.Hence,it is necessary to make a comprehensive review of recent developments.In this paper,firstly,we attempt to present the background,and then discuss research progresses.Secondly,we introduce datasets,various typical feature representation methods,and explore advanced human action recognition and posture prediction algorithms.Finally,facing the challenges in the field,this paper puts forward the research focus,and introduces the importance of action recognition and posture prediction by taking interactive cognition in self-driving vehicle as an example.

关键词： human action recognition posture prediction computer vision human-computer cooperation interactive cognition

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Survival differences between definitive radiotherapy and surgery followed by adjuvant radiotherapy in supraglottic and hypopharyngeal carcinoma

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Chinese Medical Journal 2019年第22期132卷 2698-2704页

作者： Min Zhang Xian-Shu gao Yong Qin yue Sun ming-Wei Ma Department of Radiation Oncology Peking University First HospitalPeking UniversityBeijing 100034China Department of Otorhinolaryngology-Head and Neck Surgery Peking University First HospitalBeijing 100034China Department of Otorhinolaryngology Peking University Shougang HospitalBeijing 100144China

Background:Organ preservation has long been a consideration in the treatment of supraglottic and hypopharyngeal carcin improve the quality of life(QOL).Definitive radiotherapy(DRT)with or without systematic treatment,such as chemotherapy,is always the first choice to achieve improved QOL.This retrospective study focused on the survival differences between DRT and surgery followed by adjuvant radiotherapy(S+RT)in supraglottic and hypopharyngeal carcinoma.Methods:This study included adult patients with supraglottic or hypopharyngeal carcinoma undergoing single-modality treatment with either DRT or S+RT between January 2012 and August 2016.A total of 59 patients were identified,of whom 31 were treated with DRT,and 28 were treated with S+RT.In the 31 cases of DRT,23 cases were treated with concurrent chemoradiotherapy(CRT),one case was treated with DRT plus cetuximab,and seven cases were treated with DRT alone.Of the other 28 cases of S+RT,15 cases were treated with adjuvant concurrent CRT.Survival analysis was used to compare the overall survival(OS),local recurrence-free survival(LRFS)and distant metastasis-free survival(DMFS)between DRT and S+RT groups.Results:The median follow-up was 20 months(range,4-67 months).The patients of the two groups were similar with respect to mean age,original sites,and tumor stages.The 1-,2-,and 5-year OS rates were 80.6%,53.4%,and 24.7% for the DRT group and 85.7%,67.1%,and 24.7%for the S+RT group,respectively.There was no significant difference between the two groups(x^2=3.183,P=0.074).The 1-,2-,and 5-year LRFS and DMFS were 90.4%,61.7%,and 18.0%and 87.4%,49.2%,and 9.9%,respectively,and no statistical difference was observed between the two groups(LRFS:x^2=0.028,P=0.868;DMFS:x^2=3.347,P=0.067).No significant difference was found between the two groups in acute radiotoxicity.Conclusions:Without loss of laryngeal function,the survival of DRT is comparable to that of S+RT in supraglottic and hypopharyngeal carcinoma.

关键词： Supraglottic Hypopharyngeal Definitive radiotherapy Adjuvant radiotherapy Survival

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Use of a compact high-definition two-dimensional exoscope in surgical treatment of large vestibular schwannoma

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Chinese Medical Journal 2020年第11期133卷 1292-1297页

作者： Xin Chen Xiang-Liang gao Yan Chai ming-ming Shi Jian-Ning Zhang Shu-Yuan yue Department of Neurosurgery Tianjin Medical University General HospitalTianjin Neurological InstituteKey Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous SystemMinistry of EducationTianjin Key Laboratory of InjuriesVariations and Regeneration of Nervous SystemTianjin 300052China

Background::Extra-corporeal video telescope operating monitor system provides a necessary instrument to perform high-precision neurosurgical procedures that could substitute or supplement the traditional surgical microscope.The present study was designed to evaluate a compact high-definition two-dimensional exoscope system for assisting in surgical removal of large vestibular schwannoma(VS),as an alternative to a binocular surgical microscope.Methods::Patients with Koos grade 3 and grade 4 VS undergoing surgery were enrolled in this prospective cohort study between January 2013 and June 2018.The demographics and tumor characteristics(size,Koos grade,composition[cystic or solid mass])were matched between the two groups of patients.The following outcome measurements were compared between the two groups:duration of surgery,volume of blood loss,extent of tumor resection,number of operating field adjustments,pre-and post-operative facial and cochlear nerve function evaluated at 3 months post-surgery,complications and surgeons’comfortability.Results::A total of 81 patients received tumor resection through the retrosigmoid approach under either an exoscope(cases,n=39)or a surgical microscope(control,n=42).Patients in the two groups had comparable tumor location(P=0.439),Koos grading(P=0.867),and composition(P=0.891).While no significant differences in the duration of surgery(P=0.172),extent of tumor resection(P=0.858),facial function(P=0.838),and hearing ability(P=1.000),patients operated on under an exoscope had less blood loss(P=0.036)and a fewer field adjustments(P<0.001).Both primary and assistant surgeons reported a high level of comfort operating under the exoscope(P=0.001 and P<0.001,respectively).Conclusions::The compact high-definition two-dimensional exoscope system provides a safe and efficient means to assist in removing large VSs,as compared to a surgical microscope.After the acquaintance with a visual perception through a dynamic hint and stereoscopically viewing corresponding to the motion parallax,the ex

关键词： Vestibular schwannoma Exoscope Telescope video monitor Operating microscope

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Two-dimensional reconfigurable electronics enabled by asymmetric floating gate

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Nano Research 2022年第5期15卷 4439-4447页

作者： Tengyu Jin Jing gao Yanan Wang yue Zheng Shuo Sun Lei Liu ming Lin Wei Chen Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityFuzhou 350207China Department of Physics National University of SingaporeSingapore 117542Singapore State Key Laboratory of Luminescence and Applications Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China Institute of Materials Research and Engineering(IMRE) Agency of ScienceTechnologyand Research(A*STAR)Singapore 138634Singapore Department of Chemistry National University of SingaporeSingapore 117543Singapore National University of Singapore(Suzhou)Research Institute Suzhou 215123China

Reconfigurable devices with customized functionalities hold great potential in addressing the scaling limits of silicon-based field-effect transistors(FETs).The conventional reconfigurable FETs are limited to the applications in logic circuits,and the commonly used multi-gate programming strategies often lead to high power consumption and device complexity.Here,we report a reconfigurable WSe_(2) optoelectronic device that can function as photodiode,artificial synapse,and 2-bit memory in a single device,enabled by an asymmetric floating gate(AFG)that can continuously program the device into different homojunction modes.The lateral p-n homojunction formed in the AFG device exhibits high-performance self-powered photodetection,with a responsivity over 0.17 A·W^(-1) and a wide detection spectral range from violet to near-infrared region.The AFG device can also mimic synaptic features of biological synapses and achieve distinct potentiation/depression behaviors under the modulation of both drain-source bias and light illumination.Moreover,when working as a 2-bit memory via the transition between n-n+and p-n homojunctions,the AFG device shows four distinct conductive states with a high on/off current ratio over 106 and good repeatability.Combining reduced processing complexity and reconfigurable functionalities,the WSe_(2) AFG devices demonstrate great potential towards high-performance photoelectric interconnected circuits.

关键词： reconfigurable device two-dimensional(2D)materials homojunction photodiode 2-bit memory artificial synapse

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Experimental investigation on the enhanced oil recovery efficiency of polymeric surfactant: Matching relationship with core and emulsification ability

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Petroleum Science 2023年第1期20卷 619-635页

作者： Xin Chen Yi-Qiang Li Zhe-Yu Liu Japan Trivedi Wen-Bin gao ming-yue Sui State Key Laboratory of Oil and Gas Resources and Exploration School of Petroleum EngineeringChina University of Petroleum(Beijing)Beijing 102249China Faculty of Engineering-Civil and Environmental Engineering University of AlbertaEdmontonAlberta T6G 2R3Canada Institute of Rock and Soil Mechanics Chinese Academic of SciencesWuhanHubei 430071China PetroChina Changqing Oilfield Co Research Institute of Oilfield Exploration and Development XianShaanxi 710018China

The polymeric surfactant can be used as an efficient agent for enhanced oil recovery(EOR)because of its large bulk viscosity and good interfacial activity.However,there is a sparse understanding of its matching relationship with reservoirs and emulsification occurrence conditions,which may affect its migration and EOR efficiency.One intermolecular association molecule polymeric surfactant(IAM)was synthesized by micellar polymerization and characterized with 1 H NMR,FTIR,and TGA.The matching relationship between IAM and reservoirs was evaluated by comparing the viscosity retention rate of effluent in the core flow experiments.Moreover,the effect of the matching relationship on EOR in the heterogeneous reservoir was clarified with parallel core displacement experiments by considering different flow abilities of IAM in the high-permeability layer.The occurrence conditions of in-situ emulsification of IAM were evaluated via oil-water co-injection experiments under the different injection rates and oil-water ratios.Microscopic visualization displacement was carried out to compare the micro EOR mechanisms of different chemical systems.The results show that IAM features thickening,shearing resistance,viscoelasticity,thermal stability,and interfacial activity.The matching relationship between cores and IAM could be divided as hardly injected,flow limited,and flow smoothly,corresponding to the viscosity retention ratio of80%,respectively.IAM could gain better EOR efficiency(17.69%)when its matching relationship to the high permeability layer was“flow limited”.The defined mixture capillary number shows that only when it is greater than 1×10^(3),the in-situ emulsions can be generated.Compared to HPAM,IAM could reduce IFT and form vortices to more effectively displace film and corner remaining oils by stripping and peeling off crude oil.The formed emulsion accumulated at the pore throat could further increase flow resistance,which benefits swept area enlargement.This work could provide theoretical and data s

关键词： Migration Matching relationship Viscosity retention ratio Emulsion EOR

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Influence of pre-synthesized Al_(2)O_(3)-SiC composite powder from clay on properties of low-carbon MgO-C refractories

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Journal of Iron and Steel Research(International) 2022年第7期29卷 1080-1088页

作者： Bei-yue Ma Xin-ming Ren Zhi gao Fan Qian Zhao-yang Liu Guo-qi Liu Jing-kun Yu gao-feng Fu Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Shenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina State Key Laboratory of Advance Refractories Sinosteel Luoyang Institute of Refractories Research Co.Ltd.Luoyang 471039HenanChina

To improve the properties of low-carbonization of MgO–C refractories,the introduction of composite additives is an effective strategy.Al_(2)O_(3)–SiC composite powder was prepared from clay using electromagnetic induction heating and carbon embedded methods.Further,the Al_(2)O_(3)–SiC composite powder synthesized by electromagnetic induction heating at 600 A was added into low-carbon MgO–C refractories(4 wt.%)to improve their properties.The results showed that when the addition amount of Al_(2)O_(3)–SiC composite powder is within the range of 2.5–5.0 wt.%,the properties of low-carbon MgO–C samples were significantly improved,e.g.,the apparent porosity of 7.58%–8.04%,the bulk density of 2.98–2.99 g cm-3,the cold compressive strength of 55.72–57.93 MPa,the residual strength after three air quenching at 1100°C of 74.86%–78.04%,and the decarburized layer depth after oxidized at 1400°C for 2 h of 14.03–14.87 mm.Consequently,the idea for the rapid synthesis of Al_(2)O_(3)–SiC composite powder provides an alternative low-carbon MgO–C refractories performance optimization strategy.

关键词： MgO–C refractory Electromagnetic induction heating Al_(2)O_(3)–SiC composite powder Oxidation

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Effect of Temperature on the Dynamic Recrystallization of AZ31 Alloy with Pulse Current

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Acta Metallurgica Sinica(English Letters) 2018年第12期31卷 1281-1286页

作者： Shu-Xia Lin Xing-Rong Chu Zhen-ming yue Jun gao School of Mechanical Electrical and Information Engineering Shandong University

The tensile tests of AZ31 magnesium alloy were carried out under room temperature, 100, 150 and 200 ℃ with andwithout pulse current. The effect of temperature on dynamic recrystallization （DRX） of AZ31 alloy was studied at differentconditions. One-parameter approach was used to analyze the critical conditions of DRX, the critical stress was obtainedunder different temperatures, and the related results were validated by metallography observation. The results showed thatDRX of AZ31 alloy occurred at 200 ℃ without pulse current. When pulse current with 150 Hz/50 V parameter wasapplied at room temperature, DRX occurred, while DRX was not completed until temperature over 150 ~C. With theanalysis result of critical conditions of DRX based on one-parameter approach, the relationship between critical stress andpeak stress obtained in this present study is σc = （0.746-0.773）σp.

关键词： AZ31 alloy Electroplasticity Dynamic recrystallization One-parameter approach

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