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Low Cycle Fatigue and Strengthening Mechanism of Cold Extruded Large Diameter Internal Thread of Q460 Steel

Chinese Journal of Mechanical Engineering 2016年第3期29卷 556-563页

作者： MIAO Hong MEI Qing YUAN Jingyun zheng Zaixiang JIN Yifu zuo Dunwen College of Mechanical Engineering Yangzhou University College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics

large diameter internal thread of high-strength steel（LDITHSS） manufactured by traditional methods always has the problems of low accuracy and short life. Compared with traditional methods, the cold extrusion process is an effective means to realize higher accuracy and longer life. The low-cycle fatigue properties of LDITHSS are obtained by experiments, and the initiation and propagation of fatigue cracks are observed by scanning electron microscope（SEM）. Based on the mechanical properties, surface microstructure and residual stress, the strengthening mechanism of cold extruded large diameter internal thread（LDIT） is discussed. The results show that new grains or sub-grains can be formed on the surface of LDIT due to grain segmentation and grain refinement during cold extrusion. The fibrous structures appear as elongated and streamlined along the normal direction of the tooth surface which leads to residual compressive stress on the extruded surface. The maximum tension stress of LDIT after cold extrusion is found to be 192.55 k N. Under low stress cycling, the yield stress on thread increases, the propagation rate of crack reduces, the fatigue life is thus improved significantly with decreasing surface grain diameter and the average fatigue life increases to 45.539×10~3 cycle when the maximum applied load decreases to 120 k N. The low cycle fatigue and strengthening mechanism of cold extruded LDIT revealed by this research has significant importance to promote application of internal thread by cold extrusion processing.

关键词： large diameter internal thread cold extrusion low cycle fatigue strengthening fatigue resistance

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Tuning the intensity statistics of random speckle patterns

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Chinese Physics B 2019年第5期28卷 327-331页

作者： Fan Meng Yue Zhao yun-zuo Zhang Lei Huo School of Information Science and Technology Shijiazhuang Tiedao University Department of Gastroenterology and Hepatology the Fourth Hospital of Hebei Medical University

Speckle patterns are a fundamental tool in a variety of physical and optical applications. Here, we investigate a method of precisely tuning the intensity statistics of random speckle patterns into a desirable pattern that possesses the same spatial correlation length and similar statistics distribution. This tuning mechanism relies on the derivation of the transform function and transmission matrix, which achieves different contrasts while maintaining the same average value or energy level. The statistics properties of the generated speckle patterns are further investigated by analyzing the standard deviation under different fitting parameters. Precisely tuning the intensity statistics of random speckle patterns could be useful for both fundamental research and practical applications, such as microscopy, imaging, and optical manipulation.

关键词： random speckle pattern intensity statistics local intensity transformation optical manipulation

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Valence state of transition metal center as an activity descriptor for CO_(2) reduction on single atom catalysts

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Journal of Energy Chemistry 2021年第5期30卷 444-448页

作者： Shisheng zheng Changjian zuo Xianhui Liang Shunning Li Feng Pan School of Advanced Materials Peking UniversityShenzhen Graduate SchoolShenzhen 518055GuangdongChina

Carbon dioxide(CO_(2))catalytic reduction has been passionately pursued for a long period of time due to its special importance in alleviating the greenhouse effect as well as generating valuable fuels and chemicals[1].Among the various approaches for achieving CO_(2)conversion,considerable efforts have been devoted to electrochemical reduction of CO_(2)since this technology operates at ambient and mild environments and can potentially produce various useful products[2].

关键词： CO_(2)conversion MXene based single-atom catalysts Activity descriptor Volcano shape relationship First principles calculation

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Role of surface warming in the northward shift of tropical cyclone tracks over the South China Sea in November

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Acta Oceanologica Sinica 2017年第5期36卷 67-72页

作者： SUN Jia WANG Guihua zuo Juncheng LING zheng LIU Dahai The First Institute of Oceanography State Oceanic AdministrationQingdao 266061China Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and TechnologyQingdao 266061China Institute of Atmospheric Sciences Department of Environmental Science and EngineeringFudan UniversityShanghai 200433China Key Laboratory of Coastal Disaster and Defense of Ministry of Education Hohai UniversityNanjing 210098China Guangdong Key Laboratory of Coastal Ocean Variability and Disater Prediction Guangdong Ocean UniversityZhanjiang 524088China

Tropical cyclones （TCs） formed in the Northwest Pacific Ocean （NWP） can cross the South China Sea （SCS） sometimes. It is found that the TC tracks in the SCS in November are shifted to the north after 1980 compared with those before 1980. Both data analyses and numerical simulations show that the surface warming in the SCS may contribute to this more northward shift. The warming produces a cyclonic atmosphere circulation anomaly in the northwestern SCS and an associated southerly in the central SCS steering the TCs to the north.

关键词： tropical cyclone track South China Sea sea surface temperature

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Structural,electronic,and magnetic properties of vanadium atom-adsorbed MoSe2 monolayer

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Chinese Physics B 2017年第2期26卷 392-398页

作者： Ping Llu Zhen-Zhen Qin yun-Liang Yue Xu zuo College of Electronic Information and Optical Engineering Nankai University Tianjin 300071 China

Using the first-principles calculations, we study the structural, electronic, and magnetic properties of vanadium adsorbed MoSe_2 monolayer, and the magnetic couplings between the V adatoms at different adsorption concentrations. The calculations show that the V atom is chemically adsorbed on the MoSe_2 monolayer and prefers the location on the top of an Mo atom surrounded by three nearest-neighbor Se atoms. The interatomic electron transfer from the V to the nearestneighbor Se results in the polarized covalent bond with weak covalency, associated with the hybridizations of V with Se and Mo. The V adatom induces local impurity states in the middle of the band gap of pristine MoSe_2, and the peak of density of states right below the Fermi energy is associated with the V- dz^2 orbital. A single V adatom induces a magnetic moment of 5 μBthat mainly distributes on the V-3d and Mo-4d orbitals. The V adatom is in high-spin state, and its local magnetic moment is associated with the mid-gap impurity states that are mainly from the V-3d orbitals. In addition,the crystal field squashes a part of the V-4s electrons into the V-3d orbitals, which enhances the local magnetic *** magnetic ground states at different adsorption concentrations are calculated by generalized gradient approximations（GGA） and GGA＋U with enhanced electron localization. In addition, the exchange integrals between the nearest-neighbor V adatoms at different adsorption concentrations are calculated by fitting the first-principle total energies of ferromagnetic（FM） and antiferromagnetic（AFM） states to the Heisenberg model. The calculations with GGA show that there is a transition from ferromagnetic to antiferromagnetic ground state with increasing the distance between the V adatoms. We propose an exchange mechanism based on the on-site exchange on Mo and the hybridization between Mo and V, to explain the strong ferromagnetic coupling at a short distance between the V adatoms. However, the ferromagneti

关键词： V-adatom MoSe2 monolayer magnetic moment magnetic coupling first-principles calculation

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Investigation on n-Type(-201)β-Ga_(2)O_(3)Ohmic Contact via Si Ion Implantation

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Tsinghua Science and Technology 2023年第1期28卷 150-154页

作者： Peipei Ma Jun zheng Yabao Zhang Zhi Liu Yuhua zuo Buwen Cheng State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Heavy doped n-typeβ-G_(2)O_(3)(HD-G_(2)O_(3))was obtained by employing Si ion implantation technology on unintentionally dopedβ-G_(2)O_(3)single crystal *** repair the G_(2)O_(3)lattice damage and activate the Si after implantation,the implanted substrates were annealed at 950℃,1000℃,and 1100℃,***-resolution X-ray diffraction and high-resolution transmission electron microscopy show that the ion-implanted layer has high lattice quality after high-temperature annealing at 1000℃.The minimum specific contact resistance is 9.2×10^(-5)Ω·cm^(2),which is attributed to the titanium oxide that is formed at the Ti/G_(2)O_(3)interface via rapid thermal annealing at 480℃.Based on these results,the lateralˇ-G_(2)O_(3)diodes were prepared,and the diodes exhibit high forward current density and low specific on-resistance.

关键词： β-Ga_(2)O_(3) ohmic contact ion implantation annealing activatio

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低温胁迫对黄秋葵幼苗相关生理特性的影响

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江西农业学报 2020年第9期32卷 41-44页

作者：陈瑶瑶严良文刘智成张双照郑作芸黄发茂刘晓佩福建省龙岩市农业科学研究所福建龙岩364000

以南洋黄秋葵品种为材料,采用实验室模拟早春低温胁迫环境,测定了保护酶系统、MDA含量和可溶性蛋白含量等生理指标的变化。结果表明:随着温度降低超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸氧化酶(APX)活性都呈... 详细信息

以南洋黄秋葵品种为材料,采用实验室模拟早春低温胁迫环境,测定了保护酶系统、MDA含量和可溶性蛋白含量等生理指标的变化。结果表明:随着温度降低超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸氧化酶(APX)活性都呈上升趋势;MDA和可溶性蛋白含量也呈上升的趋势;随着胁迫时间延长,SOD、CAT、POD和APX活性呈下降的趋势,MDA及可溶性蛋白质含量逐渐增加;低温处理各项指标均与对照差异显著。说明适当低温可以提高叶片中抗氧化保护酶系统相关酶活性,促进MDA和可溶性蛋白含量增加。

关键词：黄秋葵低温胁迫生理特性

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Stable isotopes of water as a tracer for revealing spatial and temporal characteristics of groundwater recharge surrounding Qinghai Lake,China

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Journal of Mountain Science 2022年第9期19卷 2611-2621页

作者： LI Dong-sheng CUI Bu-li ZHAO yun-duo zuo Feng-lin State Key Laboratory of Marine Geology Tongji UniversityShanghai 200092China School of Ocean and Earth Science Tongji UniversityShanghai 200092China School of Resources and Environmental Engineering Ludong UniversityYantai 264025China School of Natural Resources Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China Advanced Interdisciplinary Institute of Environment and Ecology Beijing Normal UniversityZhuhai 519087China

Studying spatial and temporal characteristics of regional groundwater recharge will guide the scientific management and sustainable development of regional water *** study investigated stable isotopes(δ^(18)O and δ^(2) H)of precipitation,groundwater,river water and lake water during 2019-2020 in Qinghai Lake Basin to reveal the spatial and temporal characteristics of groundwater *** local meteoric water line was simulated using ordinary least squares regression(δ^(2) H=7.80δ^(18)O+10.60).The local evaporation lines of the river water,lake water and groundwater were simulated asδ^(2) H=6.21δ^(18)O-0.72,δ^(2) H=5.73δ0-3.60 and δ^(2) H=6.59δ0+1.76,*** δ^(2) H and δ^(18)O of river water and groundwater were in more depleted values due to the recharge by precipitation at high altitudes or precipitation effects,and theδ^(2) H andδ^(18)O of the lake water were in more enriched values because of *** relationship between the δ^(2) H and δ^(18)O of groundwater and river water was not significantly different,indicating a strong hydrological connection between the groundwater and river water surrounding Qinghai ***,the maximum values of δ^(18)O and the minimum values of lc-excess of groundwater in most regions were both in August,and the minimum values of δ^(18)O and the maximum values of lc-excess of groundwater in most regions were both in ***,the groundwater was recharged by soil water with strong evaporation in August and recharged by precipitation at high altitudes in *** recharge rate of groundwater was relatively fast in areas with large slopes and large hydraulic gradients(e.g.,south of Qinghai Lake),and in areas with strong hydrological connections between the groundwater and river water(e.g.,the Buha River Valley).Those results can provide data support for protection and utilization of water resources in Qinghai Lake Basin,and provide reference for groundwater research in closed lake basi

关键词： Recharge of groundwater Hydrogen and oxygen stable isotopes Line-conditioned excess Surface water and groundwater Qinghai Lake Basin

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Hyperbolic Dependence of Moment of Inertia onω2 in Bands Involving vi13/2 Orbital and its Application in Configuration Identification

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Chinese Physics Letters 2000年第4期17卷 261-263页

作者： LU Jing-Bin LIU yun-zuo ZHANG Fan Department of Physics Jilin UniversityChangchun 130023 Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000

The so-called hyperbolic dependence of apparent moment of inertia on square of rotational frequency is developed to the bands involving^13/2 quasineutron around A-60 lighter rare-earth *** can be explained as a characteristic of strongly Coriolis mixing in the high-j unique-parity *** applications of such an effectj the previously proposed assignments of band x of^(160)Ho,π1/2^(-)[541]■vi_(13/2)band of^(170)Ta,as well as band B of 168Lu have been reviewed respectively.

关键词： bands Hyperbolic Configuration

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Incidence of unexplained intra-abdominal free fluid in patients with blunt abdominal trauma

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Hepatobiliary & Pancreatic Diseases International 2009年第6期8卷 597-601页

作者： Chen, zuo-Bing Zhang, yun Liang, Zhong-Yan Zhang, Shao-Yang Yu, Wen-Qiao Gao, Yuan zheng, Shu-Sen Zhejiang Univ Sch Med Affiliated Hosp 1 Dept Gen Surg Hangzhou 310003 Zhejiang Peoples R China Zhejiang Univ Sch Med Affiliated Hosp 1 Dept Emergency Surg Hangzhou 310003 Zhejiang Peoples R China

BACKGROUND: Intra-abdominal free fluid is commonly caused by injuries of solid or hollow organs in patients suffering from blunt abdominal trauma (BAT). However, it presents a diagnostic dilemma for surgeons when free fluid is unexplained, especially in stable BAT patients. This study was to analyze the incidence of such unexplained free fluid in BAT patients and its diagnostic value in abdominal organ injury. METHODS: Altogether 597 patients with BAT who had been treated at our trauma center over a 10-year period were reviewed. Stable patients with free fluid but without free air or definite organ injury on abdominal computed tomography were studied. Clinical management and operative findings were analyzed. RESULTS: Thirty-four (5.70%) of the 597 patients met the inclusion criteria: 24 (4.02%) underwent therapeutic exploratory laparotomy: bowel injuries were found in 13, hepatic rupture in 3, colon rupture in 3, duodenal rupture in 2, spleen rupture in 1, pancreas rupture in 1, and gallbladder perforation in 1. In 2 patients, laparotomy was nontherapeutic. Those with moderate or large amounts of free fluid were more likely to suffer from a hollow viscus injury and have a therapeutic procedure. The mean time of hospital stay for the delayed laparotomy group was longer than that for the emergency group (19 5.12 vs. 12 2.24 days; t=2.73, P<0.01). CONCLUSIONS: There was a positive correlation between the amount of unexplained free fluid and the determination of intra-abdominal organ injury. The proportion of BAT patients who required surgical intervention was high, particularly those with a moderate or large amount of free fluid, and most of them suffered from a hollow organ injury. Emergency laparotomy is recommended for these patients.

关键词： blunt abdominal injury hepatic rupture hollow viscus free fluid computed tomography

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