检索结果-南通市图书馆

Journal of Rare Earths 2014年第1期32卷 57-77页

作者： Mohammadreza Daroonparvar Muhamad Azizi Mat Yajid Noordin Mohd Yusof Hamid Reza Bakhsheshi-Rad Z.Valefi Esah Hamzah Department of Materials Manufacturing and Industrial Engineering Faculty of Mechanical Engineering Universiti Teknologi Malaysia school of Metallurgy and Materials College of Engineering University of Tehran

Bi-layered thermally grown oxide （TGO） layer plays a major role in the spallation of Y2O3 stabilized ZrO2 （YSZ） layer form the bond coat in the thermal barrier coating （TBC） systems during oxidation. On the other hand, bi-layered TGO formation and growth in the TBC systems with nanostructured YSZ have not been deeply investigated during cyclic oxidation. Hence, Inconel 738/NiCrAlY/normal YSZ and Inconel 738/NiCrAlY/nano YSZ systems were pre-oxidized at 1000 °C and then subjected to cyclic oxidation at 1150 °C. According to microstructural observations, nanostructured YSZ layer over the bond coat should have less mi-cro-cracks and pinholes, due to the compactness of the nanostructure and the presence of nano zones that resulted in lower O infiltration into the nanothermal barrier coating system, formation of thinner and nearly continuous mono-layered thermally grown oxide on the bond coat during pre-oxidation, lower spinels formation at the Al2O3/YSZ interface and finally, reduction of bi-layered thermally grown oxide thickness during cyclic oxidation. It was found that pre-heat treatment and particularly coating microstructure could influence microstructural evolution （bi-layered TGO thickness） and durability of thermal barrier coating systems during cyclic oxidation.

关键词： spinels oxidation three stages TGO growth pre-heat treatment rare earths

Improvement of the Compressive Strength of Carbon Fiber/Epoxy Composites via Microwave Curing

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & Technology 2016年第3期32卷 226-232页

作者： Xuehong Xu Xiaoqun Wang Qun Cai Xu Wang Ran Wei Shanyi Du school of Materials science and Engineering Beihang University Shanghai Aircraft manufacturing Co. Ltd.

Microwave processing was used to cure the carbon fiber/epoxy composites and designed for improving the compressive strength of the materials. By controlling the power of microwave heating, vacuum bagged laminates were fabricated under one atmosphere pressure without arcing. The physical and mechanical properties of composites produced through vacuum bagging using microwave and thermal curing were compared and the multistep （2-step or 3-step） microwave curing process for improved compressive properties was established. The results indicated that microwave cured samples had somewhat differentiated molecular structure and showed slightly higher glass transition temperature. The 2-step process was found to be more conducive to the enhancement of the compressive strength than the 3-step process. A 39% cure cycle time reduction and a 22% compressive strength increment were achieved for the composites manufactured with microwave radiation. The improvement in specific compressive strength was attributed to better interracial bonding between resin matrix and the fibers, which was also demonstrated via scanning electron microscopy analysis.

关键词： Carbon fiber Epoxy Microwave curing Compressive properties

Coupling Leveling Control Based on Fuzzy PID for Synchronous Loading System of Load-Bearing Test Bed

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2017年第6期26卷 1206-1212页

作者： ZUO Duquan QIAN Lixia YANG Tianen CUI Xiaojin LUO Qiang College of Mechanical Engineering Chongqing Three Gorges University school of manufacturing science and Engineering Sichuan University

This paper describes a 4-cylinder hydraulic circuit system controlled by a new cross-coupled fuzzy PID,and its leveling algorithm is designed to meet the demand of the loading system for test bed. In order to enable synchronous loading and implement precise leveling control,the output displacement derived from a theoretical model,called˙Zn, is tracked in real-time. Using AMEsim software,the reliability of the scheme designed by master-slave control and fuzzy PID cross coupling control have been confirmed, and have drawn a conclusion that the more serious the inconsistencies of the load for 4-cylinder are, the more size corresponding synchronization errors will be. Further,leveling experiments have demonstrated that the synchronization performance of leveling system can be improved significantly by adjusting the load values for the 4-cylinder so as to meet the demand of its un-synchronization.

关键词： Load-bearing test bed Solenoid valve Fuzzy PID Loading system Levelling

Adherent coating on gradient cemented carbide with ultrafine Ti(C_(0.5),N_(0.5))

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2015年第6期34卷 413-420页

作者： Tian-En Yang Lan Sun Ji Xiong Zhi-Xing Guo Lei Wang Ding Cao school of manufacturing science and Engineering Sichuan University Institute of System Engineering Chinese Academy of Engineering Physics

Gradient cemented carbide is usually employed as the snbstrate for coated carbide insert. In this work, gradient cemented carbide with ultrafine Ti（C0.5,N0.5） was prepared and its microstructure and properties were researched. Moreover, this novel substrate was coated to investigate cutting performance. It is found that the average WC grain size in the gradient zone is larger than that in the bulk. Owing to ultrafine Ti（C0.5,N0.5） introduction, gradient cemented carbide prepared by vacuum sintering exhibits full densification. By contrast, the gradient cemented carbide with ultrafine Ti（C0.5,N0.5） shows higher transverse rupture strength （TRS） and hardness than the homogenous one. Gradient cemented carbide suffers small TRS reduction after coating, and the bonding between coatings and gradient substrate is tidy and compact. The coated gradient cemented carbide shows much better endurance and impact resistance than the coated homogenous one. It confirms the superiority of gradient cemented carbide when used as the substrate for coating inserts.

关键词： Gradient cemented carbide UltrafineTi(C0.5,N0.5) Vacuum sintering Transverse rupturestrength Cutting performance

Effect of assisted transverse magnetic field on distortion behavior of thin-walled components in WEDM process

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第2期35卷 291-307页

作者： Yanming ZHANG Guojun ZHANG Zhen ZHANG Yi ZHANG Yu HUANG State Key Lab of Digital manufacturing Equipment&Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Department of Mechanical Engineering Northwestern UniversityEvanston 60201USA school of Aerospace Engineering Huazhong University of Science and TechnologyWuhan 430074China Guangdong HUST industrial Technology Research Institute Guangdong Provincial Key Laboratory of Digital Manufacturing EquipmentDongguan 523808China

Machining performance of thin-walled components made by aeronautical difficult-toprocess materials is a significant issue in the aviation manufacturing *** wire electric discharge machining-low speed(WEDM-LS)is one of typical non-contact machining processes without macro cutting force,which does well in removing hardness and brittleness materials via pulsed discharge at high temperature,but few researchers have studied the thermal distortion behavior leading to a considerable geometric error in the WEDM-LS of thin-walled *** this paper,a transverse magnetic field assisted method is applied for affecting the uniformity of discharge point distribution so as to reduce the distortion in WEDM-LS processing thin-wall ***,the generation mechanism of this new distortion behavior and the impact mechanism of transverse magnetic field(TMF)on distortion are demonstrated by theoretical *** order to further figure out the distortion behavior in the TMF-WEDM process,a new thermophysical model considering the discharge point distribution is established to simulate temperature field,residual stress field and distortion *** a large number of Taguchi experiments are carried out to investigate the influences of process parameters including pulse discharge energy(pulse on time,pulse off time,and current)and magnetic field strength on distortion in *** comparatively analyze simulated and experimental results,the accuracy of established thermophysical model is verified within a relative error of 18.38%in ***,it can be revealed that transverse magnetic field contribute to significantly improve the longitudinal distribution uniformity with maximum increase of 12.32%at magnetic field strength:0.15 T,leading to significant reductions of 32.77%in distortion and 22.68%in recast ***,we also presented the variation of residual stress and recast layer along thickness direction under different distortion behav

关键词： Distortion behavior Distribution of discharge points Thin-walled components Transverse magnetic field Wire electrical discharge machining

A self-organizing multimodal multi-objective pigeon-inspired optimization algorithm

在线全文

学校读者我要写书评

暂无评论

science China(Information sciences) 2019年第7期62卷 73-89页

作者： Yi HU Jie WANG Jing LIANG Kunjie YU Hui SONG Qianqian GUO Caitong YUE Yanli WANG school of Electrical Engineering Zhengzhou University industrial Technology Research Institute Zhengzhou University Computer science and Information Technology School of Science RMIT University

Multi-objective optimization algorithms have recently attracted much attention as they can solve problems involving two or more conflicting objectives effectively and efficiently. However, most existing studies focus on improving the performance of the solutions in the objective spaces. This paper proposes a novel multimodal multi-objective pigeon-inspired optimization(MMOPIO) algorithm where some mechanisms are designed for the distribution of the solutions in the decision spaces. First, MMOPIO employs an improved pigeon-inspired optimization(PIO) based on consolidation parameters for simplifying the structure of the standard PIO. Second, the self-organizing map(SOM) is combined with the improved PIO for better control of the decision spaces, and thus, contributes to building a good neighborhood relation for the improved ***, the elite learning strategy and the special crowding distance calculation mechanisms are used to prevent premature convergence and obtain solutions with uniform distribution, respectively. We evaluate the performance of the proposed MMOPIO in comparison to five state-of-the-art multi-objective optimization algorithms on some test instances, and demonstrate the superiority of MMOPIO in solving multimodal multi-objective optimization problems.

关键词： multi-objective multimodal decision space pigeon-inspired optimization PIO self-organizing map SOM

Noise Reduction for Images with Non-uniform Noise Using Adaptive Block Matching 3D Filtering

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2017年第6期26卷 1227-1232页

作者： CHEN Guangyi LUO Guangchun TIAN Ling CHEN Aiguo school of Computer science and Engineering University of Electronic Science and Technology of China Department of Mechanical and industrial Engineering Concordia University

Noise reduction is a very important topic in image processing. We propose a new method to deal with the case where the noisy image has different noise levels in different regions. The main idea is to segment automatically the noisy image into several sub-images so that each sub-image has approximately the same noise level. We perform Block matching 3D filtering(BM3D) to these subimages in order to obtain denoised sub-images. We then merge sub-images together and enhance the discontinuous regions between the sub-images by performing BM3D again on small image patches. Our experimental results show the effectiveness of this proposed method in terms of Peak signal to noise ratio(PSNR) when compared with the bivariate wavelet shrinkage and the standard BM3D method. In addition to Gaussian white noise, our method performs better than the bivariate wavelet shrinkage and the standard BM3D method even for signal dependent noise.

关键词： Image denoising noise reduction Block matching and 3D filtering(BM3D) Dual-tree complex wavelet transform(DTCWT) k-means

Effect of sintering parameters on the microstructure and thermal conductivity of diamond/Cu composites prepared by high pressure and high temperature infiltration

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2013年第2期20卷 180-186页

作者： Hui Chen Cheng-chang Jia Shang-jie Li school of Materials science and Engineering University of Science and Technology Beijing Shenzhen Haimingrun industrial Co. Ltd.

Pure Cu composites reinforced with diamond particles were fabricated by a high pressure and high temperature （HPHT） infiltration technique. Their microstructural evolution and thermal conductivity were presented as a function of sintering parameters （temperature, pressure, and time）. The improvement in interfacial bonding strength and the maximum thermM conductivity of 750 W/（m.K） were achieved at the optimal sintering parameters of 1200℃, 6 GPa and 10 min. It is found that the thermal conductivity of the composites depends strongly on sintering pressure. When the sintering pressure is above 6 GPa, the diamond skeleton is detected, which greatly contributes to the excellent thermal conductivity.

关键词： metallic matrix composites particle reinforced composites copper diamonds infiltration microstructuralevolution thermal conductivity

Effect of heating rate on the densification of NdFeB alloys sintered by an electric field

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2012年第11期19卷 1023-1028页

作者： Gang Yang, Yi Yang Dong Lu Kun-lan Huang Jun Wang school of manufacturing science and Engineering Sichuan University Chengdu 610065 China

This study introduces a novel method of electric field sintering for preparing NdFeB magnets. NdFeB alloy compacts were all sintered by electric fields for 8 min at 1000~C with different preset heating rates. The characteristics of electric field sintering and the effects of heating rate on the sintering densification of NdFeB alloys were also studied. It is found that electric field sintering is a new non-pressure rapid sintering method for preparing NdFeB magnets with fine grains at a relatively lower sintering temperature and in a shorter sintering time. Using this method, the sintering temperature and process of the compacts can be controlled accurately. When the preset heating rate in- creasing from 5 to 2000~C/s the densification of NdFeB sintered compacts gradHally improves. As the preset heating rate is 2000C/s, Nd-rich phases are small, dispersed and uniformly distributed in the sintered compact, and the magnet has a better microstructure than that made by conventional vacuum sintering. Also, the maximum energy product of the sintered magnet reaches 95% of conventionally vacuum sintered magnets.

关键词： permanent magnets electric fields sintering heating rate densification

A review on cell damage,viability,and functionality during 3D bioprinting

在线全文

学校读者我要写书评

暂无评论

Military Medical Research 2023年第5期10卷 620-635页

作者： He-Qi Xu Jia-Chen Liu Zheng-Yi Zhang Chang-Xue Xu Department of industrial Manufacturingand Systems EngineeringTexas Tech UniversityLubbockTX79409USA school of Naval Architecture and Ocean Engineering Huazhong University of Science and TechnologyWuhan430074China

Three-dimensional(3D)bioprinting fabricates 3D functional tissues/organs by accurately depositing the bioink composed of the biological materials and living *** though 3D bioprinting techniques have experienced significant advancement over the past decades,it remains challenging for 3D bioprinting to artificially fabricate functional tissues/organs with high post-printing cell viability and functionality since cells endure various types of stress during the bioprinting ***,cell viability which is affected by several factors including the stress and the environmental factors,such as pH and temperature,is mainly determined by the magnitude and duration of the stress imposed on the cells with poorer cell viability under a higher stress and a longer duration *** maintenance of high cell viability especially for those vulnerable cells,such as stem cells which are more sensitive to multiple stresses,is a key initial step to ensure the functionality of the artificial tissues/*** addition,maintaining the pluripotency of the cells such as proliferation and differentiation abilities is also essential for the 3D-bioprinted tissues/organs to be similar to native tissues/*** review discusses various pathways triggering cell damage and the major factors affecting cell viability during different bioprinting processes,summarizes the studies on cell viabilities and functionalities in different bioprinting processes,and presents several potential approaches to protect cells from injuries to ensure high cell viability and functionality.

关键词： Three-dimensional bioprinting Cell damage Shear stress Cell viability Cell functionality