检索结果-南通市图书馆

Journal of Advanced Ceramics 2022年第1期11卷 75-93页

作者： Dake ZHAO Dongjiang WU Jing SHI Fangyong NIU Guangyi MA key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of TechnologyDalian 116024China

Melt-grown alumina-based composites are receiving increasing attention due to their potential for aerospace applications;however,the rapid preparation of high-performance components remains a challenge.Herein,a novel route for 3D printing dense(key issues on the composites,including phase composition,microstructure formation/evolution,densification,and mechanical properties,are systematically investigated.The toughening and strengthening mechanisms are analyzed using classical fracture mechanics,Griffith strength theory,and solid/glass interface infiltration theory.It is demonstrated that the composites are composed of corundum,mullite,and glass,or corundum and glass.With the increase of alumina content in the initial powder,corundum grains gradually evolve from near-equiaxed dendrite to columnar dendrite and cellular structures due to the weakening of constitutional undercooling and small nucleation undercooling.The microhardness and fracture toughness are the highest at 92.5 mol%alumina,with 18.39±0.38 GPa and 3.07±0.13 MPa-m1/2,respectively.The maximum strength is 310.1±36.5 MPa at 95 mol%alumina.Strength enhancement is attributed to the improved densification due to the trace silica doping and the relief of residual stresses.The method unravels the potential of preparing dense high-performance melt-grown alumina-based composites by the DLD technology.

关键词： laser additive manufacturing alumina mullite microstructure mechanical properties

Gut microbiota-mediated modulation of lipid metabolism by punicic acid in diet-induced hepatic steatosis

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

Food Science and Human Wellness 2024年

作者： Liping Chen Yifan Lei Hengqian Lu Yongzhong Wang School of Life Sciences Anhui University Anhui key laboratory of Modern Biomanufacturing key laboratory of Human Microenvironment and precision Medicine of Anhui Higher education Institutes Anhui University

Pomegranate seed oil (PSO) mainly consisted of punicic acid (PunA)， has gained attention due to rich conjugated linolenic acids and potential application in the improvement of various diseases. The aim of this study was to explore the ability of PunA to modulate lipid metabolism associated with non-alcoholic fatty liver disease (NAFLD) and explore the emerging role of the gut microbiota in modulating hepatic lipid metabolism. In this regard， PunA’s capacity was evaluated through C57BL/6J fed with a choline and L-amino acid defined， high fat diet (CDAHFD). Mice were randomly divided into four groups: NC group， MC group， PSO group and Cur group. Collected results indicated that supplement of PunA improved hepatic lipid profile. PunA administration also ameliorated hepatic steatosis and lipid accumulation. mRNA analysis showed that PunA exerted ameliorative e?ect on hepatic lipid accumulation by downregulating the mRNA expression of Dgat1， Scd-1， Srebp-1c， but increasing expression level of Cpt-1α. Metagenomic analysis discovered that PunA increased species diversity and richness of intestinal microbiota， promoted proliferation of beneficial commensals and restraining the endotoxin-producing microorganisms in cecum of CDAHFD-administrated mice. Furthermore， PunA suppressed lipid accumulation and lipid droplet formation in a cell NAFLD model in vitro. Overall， PunA exhibited anti-lipogenic and lipid-lowering effects， improvement of intestinal flora. In summary， PunA could be a candidate for the exploitation of functional foods or nutraceuticals aiming NAFLD.

关键词：

Fixturing technology and system for thin-walled parts machining:a review

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Mechanical Engineering 2022年第4期17卷 1-32页

作者： Haibo LIU Chengxin WANG Te LI Qile BO Kuo LIU Yongqing WANG key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of TechnologyDalian 116024China

During the overall processing of thin-walled parts(TWPs),the guaranteed capability of the machining process and quality is determined by fixtures.Therefore,reliable fixtures suitable for the structure and machining process of TWP are essential.In this review,the key role of fixtures in the manufacturing system is initially discussed.The main problems in machining and workholding due to the characteristics of TWP are then analyzed in detail.Afterward,the definition of TWP fixtures is reinterpreted from narrow and broad perspectives.Fixture functions corresponding to the issues of machining and workholding are then clearly stated.Fixture categories are classified systematically according to previous research achievements,and the operation mode,functional characteristics,and structure of each fixture are comprehensively described.The function and execution mode of TWP fixtures are then systematically summarized and analyzed,and the functions of various TWP fixtures are evaluated.Some directions for future research on TWP fixtures technology are also proposed.The main purpose of this review is to provide some reference and guidance for scholars to examine TWP fixtures.

关键词： thin-walled part(TWP) fixture machining fixture categories fixture function

Bionic superhydrophobic surfaces based on topography of copper oxides

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Biosurface and Biotribology 2022年第3期8卷 199-211页

作者： Chen Chen Haiyang Zhan Xiangge Bai Zichao Yuan Lei Zhao Yahua Liu Shile Feng key laboratory for precision&non‐traditional machining technology of ministry of education Dalian University of TechnologyDalianChina

Superhydrophobic surfaces(SHSs)exist in many biological organisms endowed by spectacular surface topographies,which provide important insights to drive a paradigm shift in design of engineering surfaces.Based on this,extensive progresses have been developed on bionic superhydrophobic strategies.Among them,SHSs based on topography of copper oxides exhibit considerable application prospects because of the steerability and diversity of topography,as well as additional performances,such as antibiosis,anticorrosion and catalysis.We first present a brief overview of the discovery of natural SHSs as well as fundamental understanding of surface wetting performance.Then,the structural effects in superhydrophobic systems based on the topographies of biological organisms and copper oxides are described.Finally,we highlight the perspectives on the novel design strategies of copper oxide‐based SHSs that adapt to various practical applications.

关键词： biological organisms bionic SHSs copper‐oxides topography wetting

Subsurface damage pattern and formation mechanism of monocrystalline β-Ga_(2)O_(3) in grinding process

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Mechanical Engineering 2022年第2期17卷 117-127页

作者： Xin YANG Renke KANG Shang GAO Zihe WU Xianglong ZHU key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of TechnologyDalian 116024China

Monocrystalline beta-phase gallium oxide (β-Ga_(2)O_(3)) is a promising ultrawide bandgap semiconductor material. However, the deformation mechanism in ultraprecision machining has not yet been revealed. The aim of this study is to investigate the damage pattern and formation mechanism of monocrystalline β-Ga_(2)O_(3)in different grinding processes. Transmission electron microscopy was used to observe the subsurface damage in rough, fine, and ultrafine grinding processes. Nanocrystals and stacking faults existed in all three processes, dislocations and twins were observed in the rough and fine grinding processes, cracks were also observed in the rough grinding process, and amorphous phase were only present in the ultrafine grinding process. The subsurface damage thickness of the samples decreased with the reduction in the grit radius and the grit depth of cut. Subsurface damage models for grinding process were established on the basis of the grinding principle, revealing the mechanism of the mechanical effect of grits on the damage pattern. The formation of nanocrystals and amorphous phase was related to the grinding conditions and material characteristics. It is important to investigate the ultraprecision grinding process of monocrystalline β-Ga_(2)O_(3). The results in this work are supposed to provide guidance for the damage control of monocrystalline β-Ga_(2)O_(3)grinding process.

关键词： monocrystalline beta-phase gallium oxide grinding process subsurface damage nanocrystals amorphous phase

Etching of quartz crystals in liquid phase environment:A review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nanotechnology and precision Engineering 2024年第2期7卷 87-109页

作者： Yide Dong Yike Zhou Haizhou Huang Bosong Zhang Xihan Li Kaiwen Chen Litao Sun Guangbin Dou SEU-FEI Nano-Pico Center Key Laboratory of MEMS of Ministry of EducationSoutheast UniversityNanjing 210096People’s Republic of China Nanjing Jingxin Optoelectronics Research Institute Nanjing 210096People’s Republic of China

Quartz crystals are the most widely used material in resonant sensors,owing to their excellent piezoelectric and mechanical properties.With the development of portable and wearable devices,higher processing efﬁciency and geometrical precision are required.Wet etching has been proven to be the most efﬁcient etching method for large-scale production of quartz devices,and many wet etching approaches have been developed over the years.However,until now,there has been no systematic review of quartz crystal etching in liquid phase environments.Therefore,this article provides a comprehensive review of the development of wet etching processes and the achievements of the latest research in thisﬁeld,covering conventional wet etching,additive etching,laser-induced backside wet etching,electrochemical etching,and electrochemical discharge machining.For each technique,a brief overview of its characteristics is provided,associated problems are described,and possible solutions are discussed.This review should provide an essential reference and guidance for the future development of processing strategies for the manufacture of quartz crystal devices.

关键词： Quartz crystal Materials processing Wet etching Microfabrication Quartz MEMS

Detecting APT-Exploited Processes through Semantic Fusion and Interaction Prediction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第2期78卷 1731-1754页

作者： Bin Luo Liangguo Chen Shuhua Ruan Yonggang Luo School of Cyber Science and Engineering Sichuan UniversityChengdu610065China key laboratory of Data Protection and Intelligent Management(Sichuan University) Ministry of EducationChengdu610065China Cyber Science Research Institute Sichuan UniversityChengdu610065China

Considering the stealthiness and persistence of Advanced Persistent Threats(APTs),system audit logs are leveraged in recent studies to construct system entity interaction provenance graphs to unveil threats in a host.Rule-based provenance graph APT detection approaches require elaborate rules and cannot detect unknown attacks,and existing learning-based approaches are limited by the lack of available APT attack samples or generally only perform graph-level anomaly detection,which requires lots of manual efforts to locate attack entities.This paper proposes an APT-exploited process detection approach called ThreatSniffer,which constructs the benign provenance graph from attack-free audit logs,fits normal system entity interactions and then detects APT-exploited processes by predicting the rationality of entity interactions.Firstly,ThreatSniffer understands system entities in terms of their file paths,interaction sequences,and the number distribution of interaction types and uses the multi-head self-attention mechanism to fuse these semantics.Then,based on the insight that APT-exploited processes interact with system entities they should not invoke,ThreatSniffer performs negative sampling on the benign provenance graph to generate non-existent edges,thus characterizing irrational entity interactions without requiring APT attack samples.At last,it employs a heterogeneous graph neural network as the interaction prediction model to aggregate the contextual information of entity interactions,and locate processes exploited by attackers,thereby achieving fine-grained APT detection.Evaluation results demonstrate that anomaly-based detection enables ThreatSniffer to identify all attack activities.Compared to the node-level APT detection method APT-KGL,ThreatSniffer achieves a 6.1%precision improvement because of its comprehensive understanding of entity semantics.

关键词： Advanced persistent threat provenance graph multi-head self-attention graph neural network

Design of ultrasonic elliptical vibration cutting system for tungsten heavy alloy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Mechanical Engineering 2022年第4期17卷 163-180页

作者： Sen YIN Yan BAO Yanan PAN Zhigang DONG Zhuji JIN Renke KANG key laboratory for precision and non-traditional machining technology of the ministry of education School of Mechanical EngineeringDalian University of TechnologyDalian 116024China

Nanoscale surface roughness of tungsten heavy alloy components is required in the nuclear industry and precision instruments.In this study,a high-performance ultrasonic elliptical vibration cutting(UEVC)system is developed to solve the precision machining problem of tungsten heavy alloy.A new design method of stepped bending vibration horn based on Timoshenko’s theory is first proposed,and its design process is greatly simplified.The arrangement and working principle of piezoelectric transducers on the ultrasonic vibrator using the fifth resonant mode of bending are analyzed to realize the dual-bending vibration modes.A cutting tool is installed at the end of the ultrasonic vibration unit to output the ultrasonic elliptical vibration locus,which is verified by finite element method.The vibration unit can display different three-degree-of-freedom(3-DOF)UEVC characteristics by adjusting the corresponding position of the unit and workpiece.A dual-channel ultrasonic power supply is developed to excite the ultrasonic vibration unit,which makes the UEVC system present the resonant frequency of 41 kHz and the maximum amplitude of 14.2μm.Different microtopography and surface roughness are obtained by the cutting experiments of tungsten heavy alloy hemispherical workpiece with the UEVC system,which validates the proposed design’s technical capability and provides optimization basis for further improving the machining quality of the curved surface components of tungsten heavy alloy.

关键词： tungsten heavy alloy ultrasonic elliptical vibration cutting Timoshenko’s theory resonant mode of bending finite element method

An Improved Solov2 Based on Attention Mechanism and Weighted Loss Function for Electrical Equipment Instance Segmentation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第1期78卷 677-694页

作者： Junpeng Wu Zhenpeng Liu Xingfan Jiang Xinguang Tao Ye Zhang key laboratory of Modern Power System Simulation and Control&Renewable Energy technology Ministry of EducationNortheast Electric Power UniversityJilin132012China School of Electrical Engineering Northeast Electric Power UniversityJilin132012China Baishan Power Supply Company State Grid Jilin Electric Power CoLtd.Jilin134300China

The current existing problem of deep learning framework for the detection and segmentation of electrical equipment is dominantly related to low precision.Because of the reliable,safe and easy-to-operate technology provided by deep learning-based video surveillance for unmanned inspection of electrical equipment,this paper uses the bottleneck attention module(BAM)attention mechanism to improve the Solov2 model and proposes a new electrical equipment segmentation mode.Firstly,the BAM attention mechanism is integrated into the feature extraction network to adaptively learn the correlation between feature channels,thereby improving the expression ability of the feature map;secondly,the weighted sum of CrossEntropy Loss and Dice loss is designed as the mask loss to improve the segmentation accuracy and robustness of the model;finally,the non-maximal suppression(NMS)algorithm to better handle the overlap problem in instance segmentation.Experimental results show that the proposed method achieves an average segmentation accuracy of mAP of 80.4% on three types of electrical equipment datasets,including transformers,insulators and voltage transformers,which improve the detection accuracy by more than 5.7% compared with the original Solov2 model.The segmentation model proposed can provide a focusing technical means for the intelligent management of power systems.

关键词： Deep learning electrical equipment attention mechanism weighted loss function

An image mosaic technique with non-overlapping regions based on microscopic vision in precision assembly

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nanotechnology and precision Engineering 2023年第4期6卷 66-74页

作者： Yawei Li Xiaodong Wang Tao Wang Yi Luo key laboratory for Micro/Nano technology and System of Liaoning Province Dalian University of TechnologyDalian 116024China key laboratory for precision and non-traditional machining of ministry of education Dalian University of TechnologyDalian 116024China

Microscopic vision has been widely applied in precision assembly.To achieve sufficiently high resolution in measurements for precision assembly when the sizes of the parts involved exceed the field of view of the vision system,an image mosaic technique must be used.In this paper,a method for constructing an image mosaic with non-overlapping areas with enhanced efficiency is proposed.First,an image mosaic model for the part is created using a geometric model of the measurement system installed on a X-Y-Z precision stages with high repeatability,and a path for image acquisition is established.Second,images are captured along the same path for a specified calibration plate,and an entire image is formed based on the given model.The measurement results obtained from the specified calibration plate are utilized to identify mosaic errors and apply compensation for the part requiring measurement.Experimental results show that the maximum error is less than 4μm for a camera with pixel equivalent 2.46μm,thereby demonstrating the accuracy of the proposed method.This image mosaic technique with non-overlapping regions can simplify image acquisition and reduce the workload involved in constructing an image mosaic.

关键词： Image mosaic Microscopic vision Visual measurement precision assembly