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Development,validation,and transportability of several machine-learned,non-exercise-based VO_(2max)prediction models for older adults

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Journal of Sport and Health Science 2024年第5期13卷 611-620页

作者： benjamin T.Schumacher Michael J.LaMonte Andrea z.LaCroix Eleanor M.Simonsick Steven P.Hooker Humberto Parada Jr. John bellettiere Arun Kumar Herbert Wertheim School of Public Health and Human Longevity Science University of California San DiegoLa JollaCA 92093USA Department of Epidemiology and Environmental Health School of Public Health and Health ProfessionsUniversity at BuffaloState University of New YorkBuffaloNY 14214USA Translational Gerontology branch Intramural Research ProgramNational Institute on AgingNational Institutes of HealthBaltimoreMD 21225USA College of Health and Human Services San Diego State UniversitySan DiegoCA 92182USA Division of Epidemiology and biostatistics School of Public HealthSan Diego State UniversitySan DiegoCA 92182USA University of California San Diego Moores Cancer Center La JollaCA 92093USA Computer Science and Engineering and Halicioglu Data Science Institute University of California San DiegoLa JollaCA 92093USA

background:There exist few maximal oxygen uptake(VO_(2max))non-exercise-based prediction equations,fewer using machine learning(ML),and none specifically for older *** direct measurement of VO_(2max)is infeasible in large epidemiologic cohort studies,we sought to develop,validate,compare,and assess the transportability of several ML VO_(2max)prediction ***:The baltimore Longitudinal Study of Aging(bLSA)participants with valid VO2_(max)tests were included(n=1080).Least absolute shrinkage and selection operator,linear-and tree-boosted extreme gradient boosting,random forest,and support vector machine(SVM)algorithms were trained to predict VO_(2max)*** developed these algorithms for:(a)the overall bLSA,(b)by sex,(c)using all bLSA variables,and(d)variables common in aging ***,we quantified the associations between measured and predicted VO_(2max)and ***:The age was 69.0±10.4 years(mean±SD)and the measured VO_(2max)was 21.6±5.9 mL/kg/*** absolute shrinkage and selection operator,linear-and tree-boosted extreme gradient boosting,random forest,and support vector machine yielded root mean squared errors of 3.4 mL/kg/min,3.6 mL/kg/min,3.4 mL/kg/min,3.6 mL/kg/min,and 3.5 mL/kg/min,*** quartiles of measured VO_(2max)showed an inverse gradient in mortality *** VO_(2max)variables yielded similar effect estimates but were not robust to ***:Measured VO_(2max)is a strong predictor of *** ML can improve the accuracy of prediction as compared to simpler approaches but estimates of association with mortality remain sensitive to *** studies should seek to reproduce these results so that VO_(2max),an important vital sign,can be more broadly studied as a modifiable target for promoting functional resiliency and healthy aging.

关键词： Cardiorespiratory fitness Prediction algorithms Epidemiology Mortality

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Magnetic and Transport Properties of Mn_(0.98)Cr_(0.02)Te Epitaxial Films Grown on Al_2O_3 Substrates

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Journal of Materials Science & Technology 2014年第2期30卷 103-106页

作者： z.H.Wang D.Y.Geng J.Li Y.b.Li z.D.zhang Shenyang National Laboratory for Materials Science Institute of Metal Researchand International Centre for Materials PhysicsChinese Academy of Sciences Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of Sciences

The epitaxial Mno0.98Cr0.02Te films on single crystal Al2O3 （0001） substrates were prepared by pulsed laser deposition. The X-ray diffraction and scanning electron microscopy results showed that the good continuous epitaxial film was obtained with substrate temperature of 500 ℃. When the substrate temperature reached 700 ℃, the film was island growth and the manganese oxides phase appeared. The temperature dependence of both the magnetization and electrical resistance showed a sharp rise at around 60 K due to the magnetoelastic coupling. The temperature dependence of the electrical resistance of Mno0.98Cr0.02Te provided evidence for a transition from the metallic to semiconducting state at 305 K due to the spin disorder scattering with a large contribution from the influence of magnon drag.

关键词： Magnetic properties Mno0.98Cr0.02Te films X-ray diffraction Epitaxial film

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Mechanisms of eutectic lamellar destabilization upon rapid solidification of an undercooled Ag-39.9 at.% Cu eutectic alloy

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Journal of Materials Science & Technology 2020年第24期59卷 173-179页

作者： H.Dong Y.z.Chen z.R.zhang G.b.Shan W.X.zhang F.Liu State Key Lab.of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Yangtze River Delta Research Institute of NPU Taicang 215400China

The eutectic Ag-Cu alloys exhibiting fine Ag-Cu lamellar eutectic structure formed upon rapid solidification have great potentials being used in various engineering ***,the desired fine primary lamellar eutectic structure(PLES)is usually replaced by a coarse anomalous eutectic structure(AES)when the undercooling prior to solidification exceeds a certain *** forming mechanism of AES in the undercooled eutectic Ag-Cu alloy has been a controversial *** this work,the undercooled Ag-39.9 at.% Cu eutectic alloy is solidified under different cooling conditions by using techniques of melt fluxing and copper mold *** results show that the coupled eutectic growth of this alloy undergoes a transition from a slow eutectic-cellular growth(ECG)to a rapid eutectic-dendritic growth(EDG)above a undercooling of 72 K,accompanying with an abrupt change of the distribution and amount of AES in as-solidified *** kinds of primary lamellar eutectic structures are formed by ECG and EDG during recalescence,*** destabilization of PLES that causes the formation of AES is ascribed to two different mechanisms based on the microstructural examination and theoretical *** 72 K,the destabilization of PLES formed by slow ECG is caused by the mechanism of"termination migration"driven by interfacial *** above 72 K,the destabilization of PLES formed by rapid EDG is attributed to the unstable perturbation of interface driven by interfacial energy and solute supersaturation.

关键词： Ag-Cu alloys Rapid solidification Undercooling Eutectics Destabilization

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Structural & Magnetic Characterizations of NiLizn Nanoferrites Synthesized by Co-precipitation Method

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Journal of Materials Science & Technology 2011年第11期27卷 991-995页

作者： D.N. Rohadiana z.A.z. Jamal S.b. Jamaludin M.F. bari J. Adnan Sustainable Engineering Research Cluster Universiti Malaysia Perlis School of Microelectronic Engineering Universiti Malaysia Perlis

Synthesis of ***（0.5-x）Fe204 nanoparticles with x=0, 0.1, 0.2, 0.3, 0.4 and 0.5 were realized via coprecipitation method. X-ray diffraction （XRD） and vibrating sample magnetometer （VSM） measurements were performed on the samples to determine the characteristics of the crystal structures and the magnetic properties of the samples, respectively. The spinel phase structures of the samples were confirmed by XRD analysis. Patterns of decreased lattice parameter and increased crystallite size values were observed by increasing the Li concentration at longer synthesis reaction periods. Similarly, for the magnetic properties, both the saturation magnetization （Ms） and coercivity （Hc） were found to vary with increasing patterns at higher Li doping levels and longer synthesis reaction periods. The results and mechanisms concerned were discussed.

关键词： Lithium nickel zinc ferrite Co-precipitation Crystal structure Magnetic properties

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Microstructure evolution and hot deformation behavior of carbon nanotube reinforced 2009Al composite with bimodal grain structure

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Journal of Materials Science & Technology 2021年第11期70卷 73-82页

作者： K.Ma z.Y.Liu S.bi X.X.zhang b.L.Xiao z.Y.Ma Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of ScienceShenyang110016China School of Materials Science and Engineering University of Science and Technology of China72 Wenhua RoadShenyang110016China School of Materials Science and Engineering Guilin University of TechnologyGuilin541004China

The hot deformation behaviors of the bimodal carbon nanotube reinforced 2009Al(CNT/2009Al)composite were studied by establishing processing map and characterizing the microstructure *** results indicate that the grain size in the ultra-fine grained zones was stable during hot deformation,while the coarse grained zones were elongated with their long axis directions tending to be perpendicular to the compression *** temperature with high strain rate(LTHR),as well as high temperature with low strain rate(HTLR)could increase the length/width ratio of the coarse grained ***,LTHR and HTLR could cause the instable *** instable deformation at LTHR was induced by severe intragranular plastic deformation and the localized shear crack,while the instable deformation at HTLR resulted from the more deformation component at the coarse grained zones,and the micro-pore initiation due to CNT re-agglomeration at the boundaries between the coarse and the ultra-fine grained zones.

关键词： Carbon nanotube bimodal Aluminum matrix composite Hot deformation Processing map

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STUDY ON THE SiC_p./Al-ALLOY COMPOSITE AUTOMOTIVE bRAKE ROTORS

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Acta Metallurgica Sinica(English Letters) 2000年第4期13卷 974-980页

作者： Ding, z.L. Fan, Y.C. Qi, H.b. Ren, D.L. Guo, J.b. Jiang, z.Q. Shijiazhuang Railway Inst Shijiazhuang China

The SiCp/Al-alloy composite front brake rotors designed for Shanghai Santana cars were prepared by semi-solid stirring+liquid forging process. The composite brake rotors were subjected to dynamometer tests on a SCHENCK brake testing system, referring to TL110 standard of VOLKSWAGEN Co. The friction coefficient and thermal response during fade testing and the wear performance of the composite rotors were studied as the functions of various parameters such as braking pressures, initial speeds, initial temperatures, torque and decelerations, and were compared with those of conventional cast iron rotors. The results show that the properties of the composite rotors can achieve the requirements of commercial cast iron rotors. The results also show that the friction coefficients of the composite rotors under different braking conditions are within the deviation band specified by the TL110 standard, and the temperature rise of composite rotors is lower than that of cast iron rotors at the end of each fade stop. The wear resistance of composite rotors is higher than that of cast iron rotors. The friction mechanism and wear mechanism were analyzed.

关键词： brakes Friction Metallic matrix composites Rotors Silicon carbide Wear resistance

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EFFECT OF THE DEFECT STATES DENSITY ON OPTICAL bAND GAP OF CdIn_(2)O_(4)THIN FILM

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 403-410页

作者： H.S.San z.G.Wu b.Li b.X.Feng KeyLaboratoryforMagnetismandMagneticMaterialofMinistryofEducation LanzhouUniversityLanzhou730000China ShanghaiInstituteofTechnicalPhysics TheChineseAcademyofSciencesShanghai200083China

Transparent conducting oxides CdIn2O4 thin films were prepared by radio-frequenc y reactive sputtering from a Cd-In alloy target in Ar+O2 atmosphere. by transmis sion spectrum and Hall measurement for different samples prepared at different s ubstrate temperatures, it could be found that the carrier concentration would in crease with the decrease of substrate temperature, but absorption edge showed an abrupt variation from a blue shift to a red shift. Theoretically, the paper for mulated the effect of high-density point defects on band structures; it embodied the formation of band tailing, burstein-Moss shift and band-gap narrowing. The density of holes will influence the magnitude of optical band gap and transmitta nce of light. Since extrapolation method does not fit degenerate semiconductor m aterials, a more accurate method of obtaining optical band gap is curve fitting. In addition, ionized impurities scattering is the main damping mechanism of the free electrons in CdIn2O4 films, the density of ionized impurities induced by a ltering substrate temperature will affect the carriers mobility.

关键词： sputtering CdIn2O4 thin film electrical property optical property

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SUPERPLASTICITY AND DIFFUSION bONDING OF IN718 SUPERALLOY

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Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 307-312页

作者： W.b. Han K.F. zhang b. Wang D.z. Wu School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile speed mutation method; m reached its maximum value 0.53 at an initial strain rate of 1×10^-4s^-1 at 1253K. The diffusion bonding parameters, including the bonding temperature T, pressure p, and time t, affected the mechanism of joints. When the bonded specimen with 25μm thick nickel foil interlayer was tensile at room temperature, the shear fracture of the joints with nickel foil interlayer took place at the IN718 part. Microstructure study was carried out with the bonded samples. The microstructure shows an excellent bonding at the interfaces. The optimum parameters for the diffusion bonding are： T = 1273-1323K, p = 20-30MPa, t = 45-60min.

关键词： superplasticity diffusion bonding nickel foil IN718 alloy

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FATIGUE PROPERTIES OF AUSTEMPERED DUCTILE IRON(ADI)IN WATER ENVIRONMENT

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Acta Metallurgica Sinica(English Letters) 2004年第2期17卷 122-130页

作者： Q.z.Cai b.K.Wei Y.Tanaka StateKeyLabofPlasticFormingSimulation＆Dies／MouldTechnology FacultyofMaterialsScienceandEngineeringHuazhongUniversityofScienceandTechnologyWuhan430074China DepartmentofMechanicalSystemsEngineering MuroranInstituteofTechnologyMuroran050-8585Japan

The acicular ferrite in austempered ductile iron (ADI) matrix around graphite wascorroded preferentially in wet condition, promoting crack origination and propagationand resulting in the disappearance of ADI fatigue limit. ADI fatigue strength wasgradually reduced with increasing the time of test and was reduced by 50% in wetcondition at 10~7 cycles compared with the fatigue limit in dry condition. The fatiguestrength variation of ferritic ductile iron in wet condition was similar to that of ADI.The ferritic ductile iron, however, has better corrosion resistance so that the fatiguestrength was lowered only by 10% in wet condition at 10~7 cycles compared with thefatigue limit in dry condition. On the other hand, the fatigue limits of ADI and ferriticductile iron were dropped by 32% and 25% in tap water dipping 480h/dry conditionrespectively compared with those in dry condition. The reduction of fatigue limit wasattributed to corrosion pits formation correlated with stress concentration, resultingin origination and propagation of fatigue crack.

关键词： anstempered ductile iron water environment corrosion fatigue crack fatigue strength

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Active vibration control of functionally graded beams with piezoelectric layers based on higher order shear deformation theory

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Earthquake Engineering and Engineering Vibration 2016年第4期15卷 611-620页

作者： K. bendine F.b. boukhoulda M.Nouarit z. Satla Mechanics of Structures and Solids Laboratory Department of Mechanics Faculty of technology Djillali Liabes University of Sidi Bel-Abbes Algeria University of Lorraine Laboratoire d'Energetique et de Mecanique Theorique et Appliquee LEMTA CNRS-UMR 7563 Mines Nancy Nancy 88100 France

This paper reports on a study of active vibration control of functionally graded beams with upper and lower surface-bonded piezoelectric layers. The model is based on higher-order shear deformation theory and implemented using the finite element method （FEM）. The proprieties of the functionally graded beam （FGb） are graded along the thickness direction. The piezoelectric actuator provides a damping effect on the FGb by means of a velocity feedback control algorithm. A Matlab program has been developed for the FGb model and compared with ANSYS APDL. Using Newmark＇s method numerical solutions are obtained for the dynamic equations of FGb with piezoelectric layers. Numerical results show the effects of the constituent volume fraction and the influence the feedback control gain on the frequency and dynamic response of FGbs.

关键词： beams piezoelectric finite element method functionally graded materials vibration control

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