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A NOVEL APPROACH FOR THE PREDICTION OF SURFACE PROFILE OF OUTgOINg wORKPIECE AND THE CALCULATION OF MEAN ROLL RADIUS IN ALLOY BAR ROLLINg

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Acta Metallurgica Sinica(English Letters) 2007年第1期20卷 49-58页

作者： Y.g. Dong w.Z. Zhang J.F. Song College of Mechanical Engineering Yanshan University Qinhuangdao 066004 Ghina College of Electromechanical Engineering Harbin Institute of Technology Harbin 150001China

In alloy bar rolling process, the component of alloyed steel influenced the spread coefficient greatly, therefore, the component influence coefficient m of different alloyed steel has been determined firstly to calculate the maximum spread. Then the curvature radius of stress free surface and the ＂critical point on the contact boundary＂ have been solved, the surface profile of outgoing workpiece has been obtained. Furthermore, the formula of the equivalent contact section area has been proposed and the mean roll radius has been calculated. The bar rolling experiment and the rigid-plastic FEM （finite element method） simulation have been carried out to verify the novel approach. Compared with experimental data and simulation results, the novel approach can be used in setting processing parameter and design of finishing groove.

关键词： alloyed steel surface profile mean roll radius critical point rigid-plastic FEM (finite element method)

Prospective associations between joint categories of physical activity and insomnia symptoms with onset of poor mental health in a population-based cohort

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Journal of Sport and Health Science 2023年第3期12卷 295-303页

作者： Mitch J Duncan Elizabeth g Holliday Nicola w Burton Nicholas glozier Stina Oftedal School of Medicine and Public Health College of HealthMedicineand WellbeingThe University of NewcastleCallaghanNSW 2308Australia Priority Research Centre for Physical Activity and Nutrition The University of NewcastleCallaghanNSW 2308Australia School of Applied Psychology Griffith UniversityBrisbaneQLD 4122Australia Menzies Health Institute Queensland Griffith UniversityBrisbaneQLD 4122Australia Brain and Mind Centre Central Clinical SchoolThe University of SydneyNSW 2050Australia

Background:Physical inactivity and insomnia symptoms are independently associated with increased risk of depression and anxiety;however,few studies jointly examine these risk *** study aimed to prospectively examine the joint association of physical activity(PA)and insomnia symptoms with onset of poor mental health in ***:Participants from the 2013 to 2018 annnual waves of the Household Income and Labour Dynamics in Australia panel study who had good mental health(Mental Health Inventory-5>54)in 2013,and who completed at least 1 follow-up survey(2014-2018),were included(n=10,977).Poor mental health(Mental Health Inventory-5≤54)was assessed ***(2013)PA was classified as high/moderate/low,and insomnia symptoms(i.e.,trouble sleeping)were classified as no insomnia symptoms/insomnia symptoms,with 6 mutually exclusive PAinsomnia symptom groups *** of PA-insomnia symptom groups with onset of poor mental health were examined using discrete-time proportional-hazards logit-hazard ***:There were 2322 new cases of poor mental health(21.2%).Relative to the high PA/no insomnia symptoms group,there were higher odds(odds ratio and 95%confidence interval(95%CI))of poor mental health among the high PA/insomnia symptoms(OR=1.87,95%CI:1.57-2.23),moderate PA/insomnia symptoms(OR=1.93,95%CI:1.61-2.31),low PA/insomnia symptoms(OR=2.33,95%CI:1.96-2.78),and low PA/no insomnia symptoms(OR=1.14,95%CI:1.01-1.29)*** level of PA combined with insomnia symptoms was associated with increased odds of poor mental health,with the odds increasing as PA ***:The se findings highlight the potential benefit of interventions targeting both PA and insomnia symptoms for promoting mental health.

关键词： Depression Physical activity Sleep quality

NUMERICAL SIMULATION OF THE THERMO-MECHANICAL PROCESS FOR BEAM BLANK CONTINUOUS CASTINg

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Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 241-250页

作者： w. Chen Y.Z. Zhang C.J. Zhang L.g. Zhu B.X. wang w.g. Lu J.H. Ma Key Laboratory of Metastable Materials Science and Technology College of Materials Science and Engineering Yanshan University Qinhuangdao 066004 China College of Metallurgy and Energy Engineering Hebei Polytechnic University Tangshan 063009 China Tangshan Heavy Plate Co. Ltd. Tangshan 063610 China Hebei Jinxi Steel Stock Co. Ltd Tangshan 064302 China College of Mechanical Engineering Yanshan University Qinhuangdao 066004 China

The aim of this study was to simulate the solidification process of beam blank continuous casting, and then find the reasons for the typical defects of the beam blank. A two-dimensional transient coupled finite element model has been developed to compute the temperature and stress profile in beam blank continuous casting. The enthalpy method was used in the heat conduction equation. The thermo-mechanical property in the mushy zone was taken into consideration in this calculation. It is shown that at the mold exit the thickness of the shell had its maximum value at the flange tip and its minimum value at the fillet. The temperature had a great fluctuation on the surface of the beam blank in the secondary cooling zone. At the unbending point, the surface temperature of the web was in the brittleness temperature range under the present condition. To ensure the quality, it is necessary to weaken the intensity of secondary cooling. At the mold exit the equivalent stress and strain have higher values at the flange tip and at the web. From the spray 1 to the unbending point, the maximum values of stress and strain gradually moved to the internal section of the flange tip and the web. However, whenever, there were bigger stress and strain values near the flange tip and the web than in the other parts, it must be very easy to generate cracks at those positions. Now, online verification of this simulation has been developed, which has proved to be very useful and efficient to instruct the practical production of beam blank continuous casting.

关键词： beam blank continuous basting thermo-mechanical process simulation

Assessment of predatory ability of native and non-native freshwater gammaridean species： A rapid test with water fleas as prey

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Current Zoology 2011年第6期57卷 836-843页

作者： B.E.M.w. STOFFELS J.S. TUMMERS g. VAN DER VELDE D. PLATVOET H.w.M. HENDRIKS R.S.E.w. LEUVEN Radboud University Nijmegen Institute for Water and Wetland Research Department of Animal Ecology and Ecophysiology Heyendaalseweg 135 NL-6525 AJ Nijmegen The Netherlands Netherlands Centre for Biodiversity Naturalis P.O. Box 9517 NL-2300 RA Leiden The Netherlands Netherlands Centre for Biodiversity Naturalis Mauritskade 57 NL-1092 AD Amsterdam The Netherlands Radboud University Nijmegen Faculty of Science Department of Mathematics Heyendaalseweg 135 NL-6525 AJ Nijmegen The Netherlands Radboud University Nijmegen Institute for Water and Wetland Research Department of Environmental Science Heyendaal seweg 135 NL-6525 AJ Nijrnegen The Netherlands

Predation rate with relation to species, sex and water temperature was tested among four different gammaridean spe- cies： Dikerogammarus villosus, gammarus roeselii, gammarus pulex and gammarus fossarum. Tests were performed in micro- cosms in climate-controlled rooms at five different temperatures. Daphnia magna, a common water flea, served as prey. On ave- rage D. villosus showed the highest consumption rate of Daphnia magna over the entire temperature range, followed in decreas- ing order by g pulex, g roeselii and g fossarum. The predation rate of all species showed a distinct peak at 20~C. Correction of predation rates for body size gave somewhat different results. D. villosus is then still the most predatory of all gammaridean spe- cies tested followed by g. pulex, g. fossarum and g roeselii. The outcome of the Daphnia tests is consistent with results of other studies with different prey. This supports that the Daphnia test is a good and quick indicator of the predatory abilities in gam- maridean species at varying temperatures, and allows the prediction of how changing temperature regimes influence invasion impacts

关键词： Daphnia Temperature Predation rate Amphipods Invasions

Effect of Rotation Rate on Microstructure and Mechanical Properties of Friction Stir Spot welded DP780 Steel

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Journal of Materials Science & Technology 2016年第4期32卷 326-332页

作者： g.M.Xie H.B.Cui Z.A.Luo w.Yu J.Ma g.D.wang State Key Laboratory of Rolling and Automation Northeastern University

DP780 steel sheets consisting of ferrite and martensite were successfully friction stir spot welded （FSSw） at the rotation rates of 500 to 1500 r/min using a w-Re alloy tool, The effect of rotation rate on micro- structure and mechanical properties of the FSSw DP780 was investigated. The peak temperatures in the welds at various rotation rates were identified to be above A3 temperature. FSSw caused the dynamic recrystallization in the stir zone （SZ）, thereby producing the fine equiaxed grain structures. At the higher rotation rates of≥1000 r/min, a full martensitic structure was observed throughout the SZs, whereas at the lower rotation rate of 500 r/min, the SZ consisted of a fine dual phase structure of ferrite and mar- tensite due to the action of deformation induced ferrite transformation. The maximum average failure load as high as 18.2 kN was obtained at the rotation rate of 1000 r/min and the fracture occurred at the thinned upper sheet.

关键词： Friction stir spot weldingDual phase steelMicrostructureDeformation induced ferritetransformationMechanical property

Assessment of ghrelin and leptin receptor levels in postmenopausal women who received oral or transdermal menopausal hormonal therapy

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2012年第1期13卷 35-42页

作者： Barbara RUSZKOwSKA Alina SOKUP Arleta KULwAS Maciej w.SOCHA Krzysztof góRALCZYK Barbara góRALCZYK Danuta ROS Department of Pathophysiology Collegium Medicum in BydgoszczNicolaus Copernicus University in Toruń Department of gastroenterology Angiology and Internal DiseasesCollegium Medicum in BydgoszczNicolaus Copernicus University in Toruń Department of Obstetrics Gynecology and Oncological GynecologyCollegium Medicum in BydgoszczNicolaus Copernicus University in Toruń

Objective： In postmenopausal women, an increased leptin concentration and reduced levels of ghrelin and adiponectin were observed. The aim of this study was to evaluate the concentrations of the active form of ghrelin, total ghrelin, leptin receptor, lipoprotein（a）（Lp（a））, and plasminogen activator inhibitor type 1 （PAl-l） in postmenopausal women who received oral or transdermal menopausal hormonal therapy （MHT）. Methods： The study involved 76 healthy women： 46 women aged from 44 to 58 years who received oral （26） or transdermal （20） MHT; the control group consisted of 30 women aged from 44 to 54 years who did not receive MHT. The plasma concentrations of total ghrelin, the active form of ghrelin, Lp（a）, and PAI-I：Ag were measured by enzyme-linked immunosorbent assay （ELISA）. The concentration of the leptin receptor was measured by enzyme immunometric assay （EIA）. Results： we observed a significantly higher concentration o~ total ghrelin and the active form of ghrelin in women who received transdermal MHT in comparison with those who took oral MHT. we also found a significantly lower concentration of total ghrelin in women who received oral MHT compared with the control group. A higher concentration of PAl-1 ：Ag was found in the group of women who took transdermal MHT in comparison with those who took oral MHT and with the control group. The differences were statistically significant. Additionally, we found a significant negative correlation between the concentrations of total ghrelin and PAl-1 ：Ag and a positive correlation between the concentrations of total ghrelin and leptin receptor in women who received transdermal MHT. Conclusions： The study showed that women who used transdermal MHT had higher levels of total ghrelin than women who took oral MHT. This indicates a beneficial effect of the transdermal route of MHT. However, transdermal therapy was associated with adverse effects with regard to the observed higher levels of PAl-1 ：Ag, which in turn, can lead t

关键词： Menopausal hormonal therapy (MHT) Plasminogen activator inhibitor type 1 (PAl-l) Leptin receptor ghrelin Menopause

Conductivity and electric properties of La_(1-x)Sr_xMnO_(3-δ)nanopowders

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Journal of Rare Earths 2009年第4期27卷 651-654页

作者： R.J.wiglusz A.gaki g.Kakali A.Chuchmaa w.Strek Institute for Low Temperature and Structure Research Polish Academy of Sciences P.O.Box 937 50-442 Wroctaw Poland Chemical Engineering Department National Technical University Athens 9 Heroon Polytechniou Str. 15773 Athens Greece Electrotechnical Institute Division Electrotechnology and Materials Wroctaw Poland

La1-xSrxMnO3-δ was synthesized by the Pechini＇s method. The XRD pattern and TEM indicate the formation of the perovskite without the presence of secondary phases. It was found that La0.8Sr0.2MnO3-δsample prepared at 1000℃ in air atmospheres, contains about 13.11% of the manganese as Mn4＋ and 86.89% of the manganese as Mn3＋. The electric measurements were carded out for La0.8Sr0.2MnO3-δ nanoceramics by using impedance spectroscopy methods and found to be 0.1 S/cm at 250 ℃ similar to the typical value of La0.8Sr0.2MnO3-δ materials. Its dependence on reciprocal temperature shows quite complicated mechanism of conduction.

关键词： LSMO Pechini's method perovskite impedance spectroscopy rare earths

Thermophysical properties of the Ni-based alloy Nimonic 80A up to 2400 K

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Rare Metals 2006年第5期25卷 529-531页

作者： B.wilthan R.Tanzer w.Schützenhfer g.Pottlacher Institute of Experimental Physics Graz University of TechnologyPetersgasse 168010 GrazAustria Bhler Edelstahl gmbH Mariazellerstrasse 258605 KapfenbergAustria

Nimonic 80A is a nickel-chromium alloy which is strengthened by additions of titanium and aluminium. The alloy is used for high temperature, high strength applications. wire shaped Nimonic 80A samples are resistively volume heated as part of a fast capacitor discharge circuit. Time resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe, voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers and the radiance temperature of the sample with a pyrometer. These measurements allow to determine heat of fusion as well as heat capacity and electrical resistivity at initial geometry of Nimonic 80A as a function of temperature in the solid and in the liquid phase up to 2400 K.

关键词： thermophysical properties Nimonic 80A resistivity enthalpy heat capacity latent heat

Estimation of J—R Curves for Small-Sized COEC Specimens and Its Application Considering Crack-Tip Cons tr aints

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Acta Mechanica Solida Sinica 2019年第3期32卷 261-276页

作者： g.w.He C.Bao L.X.Cai Y.J.wu Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China

The normalization method has been employed to estimate the J-resistance (J—R) curves for C-shaped outside edge-notched compression (COEC) specimens of SA-508 steel. The COEC specimens present the lowest J—R curves in comparison with other three types of specimens. Based on the J—Q—M met hod, the constraint parame ter Q determined at the mid-plane in the through-thickness direction of the specimen is used to approximately quantify the threedimensional crack-tip constraint for COEC specimens. Combining with the previous experiments on J—R curves, the constraint-coirected J—R curves for SA-508 steel specimens are given, which may be used to predict the fracture toughness of actual cracked components in structural integrity assessment.

关键词： Ductile fracture toughness COEC specimen Dimensionless load separation principle Normalization method Crack-tip constraint J-Q-M method