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Strategy for suppressing abnormal grain growth of ZK60 Mg alloy during solution by pre-compression:A quasi-in-situ study

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Journal of Materials Science & Technology 2024年第4期171卷 115-128页

作者： Zhenxu Wang Liang Chen Jianwei Tang Cunsheng Zhang Guoqun Zhao Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinanShandong 250061China Department of Mechanical Engineering Kyushu UniversityFukuoka 819-0395Japan

Abnormal grain growth(AGG)easily takes place in Mg alloys during high-temperature solutions,result-ing in deterioration of mechanical properties.Hence,the compression prior to solution(pre-compression)was conducted to suppress AGG,and the microstructure evolution as well as suppressing mechanisms was investigated based on quasi-in-situ analysis.After compression along the transverse direction,//ED grains preferentially nucleated and rapidly grew up,and the initial//ED texture was weakened.Two grain growth modes of heat-induced and strain-induced grain boundary migrations were found.The former was attributed to the high interfacial energy of grain boundaries with large curvature.The latter consumed the adjacent grains with high storage energy,forming abnormal grains with irregular shapes.The compression with a reduction>6%could obviously suppress AGG.The suppressing effects were mainly attributed to weakening the size advantage of//ED grains,increasing nucleation,reducing grain boundary character distribution,and redistributing storage energy distribution.After 12%compression along the transverse direction,30°misorientation of//ED grains and high energy grain boundaries were reduced.The{10-12}tensile twins and{10-15}high index twins induced by com-pression increased the nucleation of static recrystallization.Beside,compression introduces high-density dislocations,which also contributed to suppressing AGG behavior during solution.

关键词： Quasi-in-situ analysis Mg alloy Abnormal grain growth compression Microstructure

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Enhanced prediction of anisotropic deformation behavior using machine learning with data augmentation

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Journal of Magnesium and Alloys 2024年第1期12卷 186-196页

作者： Sujeong Byun Jinyeong Yu Seho Cheon Seong Ho Lee Sung Hyuk Park Taekyung Lee School of Mechanical Engineering Pusan National UniversityBusan 46241South Korea School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566South Korea

Mg alloys possess an inherent plastic anisotropy owing to the selective activation of deformation mechanisms depending on the loading condition.This characteristic results in a diverse range of flow curves that vary with a deformation condition.This study proposes a novel approach for accurately predicting an anisotropic deformation behavior of wrought Mg alloys using machine learning(ML)with data augmentation.The developed model combines four key strategies from data science:learning the entire flow curves,generative adversarial networks(GAN),algorithm-driven hyperparameter tuning,and gated recurrent unit(GRU)architecture.The proposed model,namely GAN-aided GRU,was extensively evaluated for various predictive scenarios,such as interpolation,extrapolation,and a limited dataset size.The model exhibited significant predictability and improved generalizability for estimating the anisotropic compressive behavior of ZK60 Mg alloys under 11 annealing conditions and for three loading directions.The GAN-aided GRU results were superior to those of previous ML models and constitutive equations.The superior performance was attributed to hyperparameter optimization,GAN-based data augmentation,and the inherent predictivity of the GRU for extrapolation.As a first attempt to employ ML techniques other than artificial neural networks,this study proposes a novel perspective on predicting the anisotropic deformation behaviors of wrought Mg alloys.

关键词： Plastic anisotropy compression Annealing Machine learning Data augmentation

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Secure Transmission of Compressed Medical Image Sequences on Communication Networks Using Motion Vector Watermarking

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Computers, Materials & Continua 2024年第3期78卷 3283-3301页

作者： Rafi Ullah Mohd Hilmi bin Hasan Sultan Daud Khan Mussadiq Abdul Rahim Computer and Information Sciences Department Universiti Teknologi PETRONASBandar Seri Iskandar Perak32610Malaysia Department of Computer Science National University of TechnologyIslamabad46000Pakistan Interdisciplinary Research Center for Intelligent Secure Systems King Fahd University of Petroleum and MineralsDammam31261Saudi Arabia

Medical imaging plays a key role within modern hospital management systems for diagnostic purposes.compression methodologies are extensively employed to mitigate storage demands and enhance transmission speed,all while upholding image quality.Moreover,an increasing number of hospitals are embracing cloud computing for patient data storage,necessitating meticulous scrutiny of server security and privacy protocols.Nevertheless,considering the widespread availability of multimedia tools,the preservation of digital data integrity surpasses the significance of compression alone.In response to this concern,we propose a secure storage and transmission solution for compressed medical image sequences,such as ultrasound images,utilizing a motion vector watermarking scheme.The watermark is generated employing an error-correcting code known as Bose-Chaudhuri-Hocquenghem(BCH)and is subsequently embedded into the compressed sequence via block-based motion vectors.In the process of watermark embedding,motion vectors are selected based on their magnitude and phase angle.When embedding watermarks,no specific spatial area,such as a region of interest(ROI),is used in the images.The embedding of watermark bits is dependent on motion vectors.Although reversible watermarking allows the restoration of the original image sequences,we use the irreversible watermarking method.The reason for this is that the use of reversible watermarks may impede the claims of ownership and legal rights.The restoration of original data or images may call into question ownership or other legal claims.The peak signal-to-noise ratio(PSNR)and structural similarity index(SSIM)serve as metrics for evaluating the watermarked image quality.Across all images,the PSNR value exceeds 46 dB,and the SSIM value exceeds 0.92.Experimental results substantiate the efficacy of the proposed technique in preserving data integrity.

关键词： Block matching algorithm(BMA) compression full-search algorithm motion vectors ultrasound image sequence watermarking

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A multi-feature-based intelligent redundancy elimination scheme for cloud-assisted health systems

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CAAI Transactions on Intelligence Technology 2024年第2期9卷 491-510页

作者： Ling Xiao Beiji Zou Xiaoyan Kui Chengzhang Zhu Wensheng Zhang Xuebing Yang Bob Zhang School of Computer Science and Engineering Central South UniversityChangshaChina Hunan Engineering Research Center of Machine Vision and Intelligent Medicine Central South UniversityChangshaChina The College of Literature and Journalism Central South UniversityChangshaChina Institute of Automation Chinese Academy of SciencesBeijingChina Department of Computer and Information Science University of MacaoMacaoChina

Redundancy elimination techniques are extensively investigated to reduce storage overheads for cloud-assisted health systems.Deduplication eliminates the redundancy of duplicate blocks by storing one physical instance referenced by multiple duplicates.Delta compression is usually regarded as a complementary technique to deduplication to further remove the redundancy of similar blocks,but our observations indicate that this is disobedient when data have sparse duplicate blocks.In addition,there are many overlapped deltas in the resemblance detection process of post-deduplication delta compression,which hinders the efficiency of delta compression and the index phase of resemblance detection inquires abundant non-similar blocks,resulting in inefficient system throughput.Therefore,a multi-feature-based redundancy elimination scheme,called MFRE,is proposed to solve these problems.The similarity feature and temporal locality feature are excavated to assist redundancy elimination where the similarity feature well expresses the duplicate attribute.Then,similarity-based dynamic post-deduplication delta compression and temporal locality-based dynamic delta compression discover more similar base blocks to minimise overlapped deltas and improve compression ratios.Moreover,the clustering method based on block-relationship and the feature index strategy based on bloom filters reduce IO overheads and improve system throughput.Experiments demonstrate that the proposed method,compared to the state-of-the-art method,improves the compression ratio and system throughput by 9.68%and 50%,respectively.

关键词： big data cloud computing compression data compression medical applications performance evaluation

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compression Characteristic and Creep Behavior of Moraine Soil at Xingkang Bridge,West Sichuan,China

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Journal of Earth Science 2023年第4期34卷 1272-1279页

作者： Xifeng Guo Xinfu Xing Zhonghao Wang Qiang Cheng Lei Huang Ning Li Shengming Hu Chongqing Branch Institute Changjiang River Scientific Research InstituteChongqing 400026China Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources Changjiang River Scientific Research InstituteWuhan 430010China School of Civil and Environmental Engineering Harbin Institute of TechnologyShenzhen 518055China Sichuan Highway Planning SurveyDesign and Research Institute Ltd.Chengdu 610041China Engineering Research Center of Rock-Soil Drilling&Excavation and Protection Ministry of EducationChina University of GeosciencesWuhan 430074China Badong National Observation and Research Station of Geohazards China University of GeosciencesWuhan 430074China Construction Branch State Grid Ningxia Electric Power Co.Ltd.Yinchuan 750002China National and Provincial Joint Engineering Laboratory for the Hydraulic Engineering Safety and Efficient Utilization of Water Resources of Poyang Lake Basin Nanchang Institute of TechnologyNanchang 330099China

The compression and creep characteristics of moraine soil are important mechanical properties of geomaterials to be analyzed during the construction process of engineering projects.However,related references about these characteristics through large-size in-situ tests have rarely been reported.In this study,in-situ tests of particle size distribution,compression deformation,and compression creep were conducted at the Xingkang Bridge,West Sichuan,China.The results show that the uniformity coefficient of moraine soil ranges from 12.1 to 183.3,and gradation coefficient ranges from 0.4 to 2.8.The total compression deformations of moraine samples during the conventional compression deformation test are 4.70,4.07,and 0.47 mm,and their residual deformations are 2.81,2.45,and 0.22 mm,respectively.The deformation modulus ranges from 127.3 to 676.4 MPa,and elastic modulus ranges from 316.3 to 765.7 MPa.During compression creep tests,moraine soil enters the steady creep stage after 3.8 h of loading pressure at 445 k Pa,and it keeps steady after 14 h of loading pressure at 900 k Pa.The Burgers model and generalized Kelvin model predict the deformation well in transient,deceleration and steady creep stages.Results provide a valuable reference for the analysis of the compression deformation and creep behavior of moraine soil during engineering construction and management.

关键词： moraine compression creep in-situ mechanical properties.

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compression of surface texture acceleration signal based on spectrum characteristics

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Virtual Reality & Intelligent Hardware 2023年第2期5卷 110-123页

作者： Dongyan NIE Xiaoying SUN College of Communication Engineering Jilin UniversityChangchun 130022China International Center of Future Science Jilin UniversityChangchun 130012China

Background Adequate data collection can enhance the realism of online rendering or offline playback of haptic surface textures.A parallel challenge is to reduce communication delays and improve storage space utilization.Methods Based on the similarity of the short-term amplitude spectrum trend,this study proposes a frequency-domain compression method.A compression framework is designed,which first maps the amplitude spectrum into grayscale images,compresses them with a still image compression method,and then adaptively encodes the maximum amplitude and part of the initial phase for each time window to achieve the final compression.Results The comparison between the original signal and the recovered signal shows that when the time-frequency similarity is 90%,the average compression ratio of our method is 9.85%in the case of a single interaction point.The subjective score for similarity was found to be high,with an average of 87.85.Conclusions Our method can be used for offline compression of vibrotactile data.For multi-interaction points in space,the trend similarity grayscale image can be reused,and the compression ratio is further reduced.

关键词： compression Vibrotactile Haptics Surface texture Spectrum characteristics

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Hot compression Behavior of Mg-Gd-Y-Zn-Zr Alloy Containing LPSO with Different Morphologies

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Acta Metallurgica Sinica(English Letters) 2023年第10期36卷 1680-1698页

作者： Rui Guo Xi Zhao Bo-Wen Hu Xue-Dong Tian Qiang Wang Zhi-Min Zhang School of Material Science and Engineering North University of ChinaTaiyuan030051China School of Aeronautics and Astronautics North University of ChinaTaiyuan030051China

In this study,hot compression behavior of as-homogenized Mg-9Gd-4Y-2Zn-0.5Zr alloys containing long period ordered(LPSO)phases with different initial morphologies was investigated under a strain rate of 0.01 s−1 at 450°C.The microstructure,texture evolution and dynamic recrystallization(DRX)mechanism under different strains(0.1,0.3,0.5,0.7,and 1.4)were studied.Under compression conditions,the block-shape phase and deformedα-Mg matrix were regularly arranged vertically in the compression direction(CD).The particle phase(Mg5RE)and amount of kink bands were produced.The degree of kink increased initially and decreased significantly when the deformation strain reached 1.4.Three DRX mechanisms were produced during the compression process:(i)The block LPSO,Mg5RE and Zr-Zn phase activated DRX through the particle stimulated nucleation(PSN)mechanism.(ii)Several DRX activated on the serrated grain boundary between the two parent grains through discontinuous DRX(DDRX)mechanism.(iii)A large number of kink bands and larger spacing of lamellar LPSO increased the nucleation of DRX through continuous DRX(CDRX)mechanism.The combination of different recrystallization mechanisms has evident effects on grain refinement.DRX increased as compression proceeds,and the texture was gradually weakened.

关键词： Mg-Gd-Y-Zn-Zr alloy compression Long period ordered(LPSO)phase Recrystallization mechanism

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An Experimental Study of Composite Columns Filled with Eucalyptus nitens Timber under Axial compression

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Journal of Renewable Materials 2023年第2期11卷 825-836页

作者： Yingyao Cheng Xudong Chen Huaming An Huimin Wang Kai Tao Faulty of Public Security and Emergency Management Kunming University of Science and TechnologyKunming650093China School of Engineering University of TasmaniaHobartTAS 7001Australia School of Civil Engineering Suzhou University of Science and TechnologySuzhou215011China College of water conservancy and Hydropower Engineering Hohai UniversityNanjing210098China College of Automation&College of Artificial Intelligence Nanjing University of Posts and TelecommunicationsNanjing210023China

Eucalyptus nitens(E.nitens)has been much used for producing paper but also shows promise for structural applications.In this study,static compressive tests were undertaken to examine its suitability to be used in an innovative composite column.The composite column was comprised of a rectangular steel tube with E.nitens timber infill.The nonlinear compressive behaviour of the composite column filled with E.nitens wood for both dry and wet conditions was examined.The same tests on rectangular steel tubes and bare dry and wet E.nitens samples were also undertaken as a comparison.For samples with different conditions,the ultimate capacity was evaluated and the effect of each condition on the compressive behaviour of the composite column was clarified.The steel tubes showed greater ductile behaviour,and more ductility was found in the wet samples.The steel tubes with E.nitens timber infill samples exhibited a greater linear elastic range connected with higher maximum loads,while the bare timber samples could support only lower maximum loads.The results from this research were promising for the use of rectangular steel tubes with E.nitens timber infill in structural applications.

关键词： Hollow steel tubes Eucalyptus high moisture content composite column with timber infill compression

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A New Multi Chaos-Based compression Sensing Image Encryption

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Computers, Materials & Continua 2023年第7期76卷 437-453页

作者： Fadia Ali Khan Jameel Ahmed Suliman A.Alsuhibany Department of Electrical Engineering Riphah International UniversityIslamabad44000Pakistan Department of Computer Science College of ComputerQassim UniversityBuraydah51452Saudi Arabia

The advancements in technology have substantially grown the size of image data.Traditional image encryption algorithms have limited capabilities to deal with the emerging challenges in big data,including compression and noise toleration.An image encryption method that is based on chaotic maps and orthogonal matrix is proposed in this study.The proposed scheme is built on the intriguing characteristics of an orthogonal matrix.Gram Schmidt disperses the values of pixels in a plaintext image by generating a random orthogonal matrix using logistic chaotic map.Following the diffusion process,a block-wise random permutation of the data is performed using multi-chaos.The proposed scheme provides sufficient security and resilience to JPEG compression and channel noise through a series of experiments and security evaluations.It enables Partial Encryption(PE)for faster processing as well as complete encryption for increased security.The higher values of the number of pixels change rates and unified average change intensity confirm the security of the encryption scheme.In contrast to other schemes,the proposed approach can perform full and partial encryption depending on security requirements.

关键词： Chaos compression image encryption

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Strain-Rate Dependency of a Unidirectional Filament Wound Composite under compression

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Computer Modeling in Engineering & Sciences 2023年第12期137卷 2149-2161页

作者： Stepan Konev Victor A.Eremeyev Hamid M.Sedighi Leonid Igumnov Anatoly Bragov Aleksandr Konstantinov Ayaulym Kuanyshova Ivan Sergeichev Skolkovo Institute of Science and Technologies Center for Materials TechnologiesMoscowRussia National Research Lobachevsky State University of Nizhny Novgorod Nizhny NovgorodRussia Dipartimento di Ingegneria Civile Ambientale e Architettura(DICAAR)Universitàdegli Studi di CagliariCagliari(CA)Italy Mechanical Engineering Department Faculty of EngineeringShahid Chamran University of AhvazAhvazIran Drilling Center of Excellence and Research Center Shahid Chamran University of AhvazAhvazIran

This article presents the results of experimental studies concerning the dynamic deformation and failure of a unidirectional carbon fiber reinforced plastic(T700/LY113)under compression.The test samples were manufactured through the filament winding of flat plates.To establish the strain rate dependencies of the strength and elastic modulus of the material,dynamic tests were carried out using a drop tower,the Split Hopkinson Pressure Bar method,and standard static tests.The samples were loaded both along and perpendicular to the direction of the reinforcing fiber.The applicability of the obtained samples for static and dynamic tests was confirmed through finite elementmodeling and the high-speed imaging of the deformation and failure of samples during testing.As a result of the conducted experimental studies,static and dynamic stress-strain curves,time dependencies of deformation and the stress and strain rates of the samples during compression were obtained.Based on these results,the strain rate dependencies of the strength and elasticity modulus in the strain rate range of 0.001-6001/s are constructed.It is shown that the strain rate significantly affects the strength and deformation characteristics of the unidirectional carbon fiber composites under compression.An increase in the strain rate by 5 orders of magnitude increased the strength and elastic modulus along the fiber direction by 42%and 50%,respectively.Perpendicular loading resulted in a strength and elastic modulus increase by 58%and 50%,respectively.The average strength along the fibers at the largest studied strain rate was about 1000MPa.The obtained results can be used to design structural elements made of polymer composite materials operating under dynamic shock loads,as well as to build models of mechanical behavior and failure criteria of such materials,taking into account the strain rate effects.

关键词： High strain rate composites filament winding dynamic strength Split Hopkinson Pressure Bar compression

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