检索结果-南通市图书馆

A novel solution treatment and aging for powder bed fusion-laser beam Ti-6Al-2Sn-4Zr-6Mo alloy:Microstructural and mechanical characterization

引用

International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 414-424页

作者： Gianluca Pirro Alessandra Martucci Alessandro Morri Mariangela Lombardi Lorella Ceschini department of Industrial engineering(DIN) Alma Mater Studiorum-University of BolognaBologna 40136Italy department of Applied Science and Technology(DISAT) Politecnico di TorinoTorino TO 10129Italy

Ti-6Al-4Zr-2Sn-6Mo alloy is one of the most recent titanium alloys processed using powder bed fusion-laser beam(PBF-LB)*** alloy has the potential to replace Ti-6Al-4V in automotive and aerospace applications,given its superior mechanical properties,which are approximately 10%higher in terms of ultimate tensile strength(UTS)and yield strength after appropriate heat *** as-built conditions,the alloy is characterized by the presence of soft orthorhombicα″martensite,necessitating a postprocessing heat treatment to decompose this phase and enhance the mechanical properties of the ***,PBFed Ti6246 components undergo an annealing process that transforms theα″martensite into anα-βlamellar *** primary objective of this research was to develop a solution treatment and aging(STA)heat treatment tailored to the unique microstructure produced by the additive manufacturing process to achieve an ultrafine bilamellar microstructure reinforced by precipitation *** study investigated the effects of various solution temperatures in theα-βfield(ranging from 800 to 875℃),cooling media(air and water),and aging time to determine the optimal heat treatment parameters for achieving the desired bilamellar *** each heat treatment condition,differentα-βmicrostructures were found,varying in terms of theα/βratio and the size of the primaryα-phase *** attention was given to how these factors were influenced by increases in solution temperature and how microhardness correlated with the percentage of the metastableβphase present after *** tests were performed on samples subjected to the most promising heat treatment parameters.A comparison with literature data revealed that the optimized STA treatment enhanced hardness and UTS by13%and 23%,respectively,compared with those of the annealed *** surface analyses were conducted to investigate fracture mechanisms.

关键词： powder bed fusion-laser beam titanium alloys heat treatments mechanical properties fractographic analysis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Machine learning driven rational design of dual atom catalysts on graphene for carbon dioxide electroreduction

引用

Nano Research 2025年第1期18卷 186-194页

作者： Dongxu Jiao Xinyi Li Mingzi Sun Lin Liu Jinchang Fan Jingxiang Zhao Bolong Huang Xiaoqiang Cui State Key Laboratory of automotive Simulation and Control School of Materials Science and Engineeringand Key Laboratory of Automobile Materials of MOEJilin UniversityChangchun 130012China department of Applied Biology and Chemical Technology The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina College of Chemistry and Chemical engineering and Key Laboratory of Photonic and Electronic Bandgap MaterialsMinistry of EducationHarbin Normal UniversityHarbin 150025China

The development of high-performance atomiccatalysts for the carbon dioxide reduction reaction(CO_(2)RR)is atime-consuming process due to the complexity of the reactionmechanism and the uncertainty of the active ***,wehave proposed combining density functional theory(DFT)andmachine learning(ML)to investigate the potential of topologicalgraphene-based dual-atom catalysts(DACs)as CO_(2)*** analyzing the ML results,we identify thenumber of d-orbital electrons in the active site as a key factorinfluencing the CO_(2)RR catalytic ***,wepropose a simple descriptor to measure the CO_(2)RR activity ofthese *** findings provide plausible explanations for thesynergistic interactions between bimetallic atoms in CO_(2)RR andallow us to screen the homogeneous Ni-Ni pair as the mostpromising dual-atom *** work offers a fast MLapproach based on limited DFT calculations to predict the mostelectroactive and stable DACs on carbon support for CO_(2)RR,facilitating rapid screening of high-performance dual-atomcatalysts.

关键词： CO_(2)reaction reduction dual-atom catalysts density functional theory machine learning

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Turbulence modelling of the aerodynamic interaction ofOGV wakes and diffuser flow

引用

航空动力学报 2011年第10期26卷 2302-2312页

作者： Page Gary McGuirk Jim department of Aeronautical and automotive engineering Loughborough University

Different turbulence closures were used to predict the flow interaction between the wakes created by compressor outlet guide vanes(OGVs) and a downstream annular *** statistical turbulence models were tested based on the classical Reynolds-averaged Navier-Stokes(RANS) *** high-Re and low-Re(Launder-Sharma) versions of the k-ε model were applied to a selected test problem for OGV wake/diffuser *** test problem was specifically chosen because experimentally determined inlet conditions and both profile and performance data were available to validate predictions.A preliminary study was also reported of the more advanced large eddy simulation(LES) *** LES sub-grid-scale(SGS) model was the basic Smagorinsky eddy viscosity assumption,with a Van-Driest damping function for improved capture of near-wall viscous *** between the two RANS models showed little difference in terms of velocity contours at OGV trailing edge and diffuser *** terms of overall diffuser performance(static pressure recovery and total pressure loss coefficients),the high-Re model was shown to agree well with experimental *** preliminary LES study indicates the highly unsteady character of the OGV wake flow,but requires improved treatment of inlet conditions.

关键词： outlet guide vane(OGV) wakes diffuser flow interaction Reynolds-averaged Navier-Stokes(RANS) modelling large eddy simulation(LES) modelling

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Multi-scale Studies of Glass Transition and Uniaxial Tensile Properties of a Commercially Available Epoxy Adhesive Using Experimental Measurements and Molecular Dynamics Simulation

引用

Chinese Journal of Polymer Science 2015年第3期33卷 465-474页

作者：姚力 State Key Laboratory of automotive Safety and Energy Department of Automotive EngineeringTsinghua University

In this study, the glass transition and uniaxial tensile properties of a commercially available epoxy adhesive were investigated using experimental measurements and molecular dynamics （MD） simulation. Differential scanning calorimetry （DSC） was used to study the change of glass transition temperature （Tg） with cross-link density （CLD）. Uniaxial tensile test was performed to measure the Young＇s modulus （E）, Poisson＇s ratio （v） and yielding strength （tyv）. In MD simulation, the complicated epoxy system was simplified as the mixture of two kinds of simple molecules, with the key information well preserved and the less important details omitted. The molecular model of the cross-linked epoxy network was constructed and its mechanical properties were calculated using MD simulation. Overall, the MD simulation results agreed with experimental ones, which proved the validity of the molecular model and justified the simplification method of the industry- level epoxy system.

关键词： Epoxy adhesive Glass transition temperature Uniaxial tension Experiment Molecular dynamics simulation.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Comparison of different techniques for time-frequency analysis of internal combustion engine vibration signals

引用

Journal of Zhejiang University-Science A(Applied Physics & engineering) 2011年第7期12卷 519-531页

作者： Yang JIN Zhi-yong HAO Xu ZHENG department of Energy engineering Zhejiang University Hangzhou 310027 China department of automotive engineering Hubei University of Automotive Technology Shiyan 442002 China

In this study,we report an analysis of cylinder head vibration signals at a steady engine speed using short-time Fourier transform(STFT).Three popular time-frequency analysis techniques,i.e.,STFT,analytic wavelet transform(AWT) and S transform(ST),have been *** and ST are often applied in engine signal *** particular,an AWT expression in terms of the quality factor Q and an analytical relationship between ST and AWT have been *** time-frequency resolution of a Gaussian function windowed STFT was studied via numerical *** on the simulation,the empirical limits for the lowest distinguishable frequency as well as the time and frequency resolutions were *** can provide insights for window width selection,spectrogram interpretation and artifact *** function windowed STFTs were applied to some cylinder head vibration *** spectrograms of the same signals from ST and AWT were also determined for *** results indicate that the uniform resolution feature of STFT is not necessarily a disadvantage for time-frequency analysis of vibration signals when the engine is in stationary state because it can more accurately localize the frequency components excited by transient excitations without much loss of time resolution.

关键词： Short-time Fourier transform(STFT) Gaussian window Time-frequency resolution limits Internal combustion(IC) engine Vibration signals Analytic wavelet transform(AWT) S transform(ST)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Isothermal study of effusion cooling flows using a large eddy simulation approach

引用

航空动力学报 2009年第4期24卷 729-739页

作者： W.P.Bennett J.J.Mc Guirk Aeronautical and automotive engineering department Loughborough University

An isothermal numerical study of effusion cooling flow is conducted using a large eddy simulation(LES) *** main types of cooling are considered,namely tangential film cooling and oblique patch effusion *** represent tangential film cooling,a simplified model of a plane turbulent wall jet along a flat plate in quiescent surrounding fluid is *** contrast to a classic turbulent boundary layer flow,the plane turbulent wall jet possesses an outer free shear flow region,an inner near wall region and an interaction region,characterised by substantial levels of turbulent shear stress *** shear stress characteristics hold significant implications for RANS modelling,implications that also apply to more complex tangential film cooling flows with non-zero free stream *** LES technique used in the current study provides a satisfactory overall prediction of the plane turbulent wall jet flow,including the initial transition region,and the characteristic separation of the zero turbulent shear stress and zero shear strain *** effusion patch cooling is modelled using a staggered array of 12 rows of effusion holes,drilled at 30° to the flat plate *** effusion holes connect two channels separated by the flat ***,these comprise of a channel representing the combustion chamber flow and a cooling air supply channel.A difference in pressure between the two channels forces air from the cooling supply side,through the effusion holes,and into the combustion chamber *** from successive effusion rows coalesces to form an aerodynamic film between the combustion chamber main flow and the flat *** practical applications,this film is used to separate the hot combustion gases from the combustion chamber *** numerical model is shown to be capable of accurately predicting the injection,penetration,downstream decay,and coalescence of the effusion *** addition,the numerical model captures entrainmen

关键词： effusion cooling large eddy simulation isothermal analysis film cooling turbulent wall jet

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Semi-empirical modeling of volumetric efficiency in engines equipped with variable valve timing system

引用

Journal of Central South University 2016年第12期23卷 3132-3142页

作者： Mostafa Ghajar Amir Hasan Ka Kaee Behrooz Mashadi department of automotive engineering Iran university of Science and Technology

Volumetric efficiency and air charge estimation is one of the most demanding tasks in control of today's internal combustion ***,using three-way catalytic converter involves strict control of the air/fuel ratio around the stoichiometric point and hence requires an accurate model for air charge ***,high degrees of complexity and nonlinearity of the gas flow in the internal combustion engine make air charge estimation a challenging *** is more obvious in engines with variable valve timing systems in which gas flow is more complex and depends on more functional *** results in models that are either quite empirical(such as look-up tables),not having interpretability and extrapolation capability,or physically based models which are not appropriate for onboard *** these problems,a novel semi-empirical model was proposed in this work which only needed engine speed,load,and valves timings for volumetric efficiency *** accuracy and generalizability of the model is shown by its test on numerical and experimental data from three distinct *** test errors are 0.0316,0.0152 and 0.24 for the three engines,*** the performance and complexity of the model were compared with neural networks as typical black box *** the complexity of the model is less than half of the complexity of neural networks,and its computational cost is approximately 0.12 of that of neural networks and its prediction capability in the considered case studies is usually *** results show the superiority of the proposed model over conventional black box models such as neural networks in terms of accuracy,generalizability and computational cost.

关键词： engine modeling modeling and simulation spark ignition engine volumetric efficiency variable valve timing

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Intelligent computing budget allocation for on-road tra jectory planning based on candidate curves

引用

Frontiers of Information Technology & Electronic engineering 2016年第6期17卷 553-565页

作者： Xiao-xin FU Yong-heng JIANG De-xian HUANG Jing-chun WANG Kai-sheng HUANG department of Automation Tsinghua University department of automotive engineering Tsinghua University

In this paper, on-road trajectory planning is solved by introducing intelligent computing budget allocation(ICBA) into a candidate-curve-based planning algorithm, namely, ordinal-optimization-based differential evolution(OODE). The proposed algorithm is named IOODE with ‘I' representing ICBA. OODE plans the trajectory in two parts: trajectory curve and acceleration profile. The best trajectory curve is picked from a set of candidate curves, where each curve is evaluated by solving a subproblem with the differential evolution(DE) algorithm. The more iterations DE performs, the more accurate the evaluation will become. Thus, we intelligently allocate the iterations to individual curves so as to reduce the total number of iterations performed. Meanwhile, the selected best curve is ensured to be one of the truly top curves with a high enough probability. Simulation results show that IOODE is 20% faster than OODE while maintaining the same performance in terms of solution quality. The computing budget allocation framework presented in this paper can also be used to enhance the efficiency of other candidate-curve-based planning methods.

关键词： Intelligent computing budget allocation Trajectory planning On-road planning Intelligent vehicles Ordinal optimization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Easy calibration method of vision system for in-situ measurement of strain of thin films

引用

中国有色金属学会会刊：英文版 2009年第B9期19卷 243-249页

作者： Jun-Hyub PARK Dong-Joong KANG Myung-Soo SHIN Sung-Jo LIM Son-Cheol YU Kwang-Soo LEE Jong-Eun HA Sung-Hoon CHOA department of Mechatronics engineering Tongmyong University School of Mechanical engineering Pusan National University department of automotive engineering Hoseo University department of automotive engineering Seoul National University of Technology department of Nano/IT engineering Seoul N ational University of Technology

An easy calibration method was presented for in-situ measurement of displacement in the order of nanometer during micro-tensile test for thin films by using CCD camera as a sensing device. The calibration of the sensing camera in the system is a central element part to measure displacement in the order of nanometer using images taken with the camera. This was accomplished by modeling the optical projection through the camera lens and relative locations between the object and camera in 3D space. A set of known 3D points on a plane where the film is located on is projected to an image plane as input data. These points, known as a calibration points, are then used to estimate the projection parameters of the camera. In the measurement system of the micro-scale by CCD camera, the calibration data acquisition and one-to-one matching steps between the image and 3D planes need precise data extraction procedures and repetitive user's operation to calibrate the measuring devices. The lack of the robust image feature extraction and easy matching prevent the practical use of these methods. A data selection method was proposed to overcome these limitations and offer an easy and convenient calibration of a vision system that has the CCD camera and the 3D reference plane with calibration marks of circular type on the surface of the plane. The method minimizes the user's intervention such as the fine tuning of illumination system and provides an efficient calibration method of the vision system for in-situ axial displacement measurement of the micro-tensile materials.

关键词：标定方法视觉系统原位测试应变薄膜松

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Potential Bands of Sentinel-2A Satellite for Classification Problems in Precision Agriculture

引用

International Journal of Automation and computing 2019年第1期16卷 16-26页

作者： Tian-Xiang Zhang Jin-Ya Su Cun-Jia Liu Wen-Hua Chen department of Aeronautical and automotive engineering Loughborough University

Various indices are used for assessing vegetation and soil properties in satellite remote sensing applications. Some indices,such as normalized difference vegetation index(NDVI) and normalized difference water index(NDWI), are capable of simply differentiating crop vitality and water stress. Nowadays, remote sensing capabilities with high spectral, spatial and temporal resolution are available to analyse classification problems in precision agriculture. Many challenges in precision agriculture can be addressed by supervised classification, such as crop type classification, disease and stress(e.g., grass, water and nitrogen) monitoring. Instead of performing classification based on designated indices, this paper explores direct classification using different bands information as features. Land cover classification by using the recently launched Sentinel-2A image is adopted as a case study to validate our method. Four approaches of featured band selection are compared to classify five classes(crop, tree, soil, water and road) with the support vector machines(SVMs)algorithm, where the first approach utilizes traditional empirical indices as features and the latter three approaches adopt specific bands(red, near infrared and short wave infrared) related to indices, specific bands after ranking by mutual information(MI), and full bands of on-board sensors as features, respectively. It is shown that a better classification performance can be achieved by directly using the selected bands after MI ranking compared with the one using empirical indices and specific bands related to indices, while the use of all 13 bands can marginally improve the classification accuracy than MI based one. Therefore, it is recommended that this approach can be applied for specific Sentinel-2A image classification problems in precision agriculture.

关键词： Sentinel-2A remote sensing image classification supervised learning precision agriculture

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：