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Hot cracking in AZ31 and AZ61 Magnesium Alloy

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journal of Materials Science & Technology 2011年第7期27卷 633-640页

作者： c.j. Huang c.M. cheng c.P. chou F.H. chen Department of Mechanical Engineering National Chiao Tung University Hsinchu 300 Taiwan China Department of Industrial Education National Taiwan Normal University Taipei 106 Taiwan China

This paper examined the impact of the number of thermal cycles and augmented strain on hot cracking in AZ31 and AZ61 magnesium alloy. Statistical analyses were performed. Following observation using a scanning electron microscope （SEM）, an energy dispersive spectrometer （EDS） was used for component analysis. Results showed that Al content in magnesium alloy has an effect on hot cracking susceptibility. In addition, the nonequilibrium solidification process produced segregation in Al content, causing higher liquid Mg-alloy rich Al content at grain boundaries, and resulting into liquefied grain boundaries of partially melted zone （PMZ）. In summary, under multiple thermal cycles AZ61 produced serious liquation cracking. AZ61 has higher （6 wt%） Al content and produced much liquefied Mg17Al12 at grain boundaries under multiple thermal cycles. The liquefied Mg17Al12 were pulled apart and hot cracks formed at weld metal HAZ due to the augmented strain. Since AZ31 had half the Al content of AZ61, its hot-cracking susceptibility was lower than AZ61. In addition, AZ61 showed longer total crack length （TcL） in one thermal cycle compared to that in three thermal cycles. This phenomenon was possibly due to high-temperature gasification of Al during the welding process, which resulted in lower overall Al content. consequently, shorter hot cracks exhibited in three thermal cycles. It was found the Al content of AZ31 and AZ61 can be used to assess the hot-cracking susceptibility.

关键词： Varestraint test Thermal cycles Hot-cracking susceptibility Gas tungsten arc welding (GTAW) AZ31 AZ61

Image Recognition of citrus Diseases Based on Deep Learning

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computers, Materials & continua 2021年第1期66卷 457-466页

作者： Zongshuai Liu Xuyu Xiang jiaohua Qin Yun Tan Qin Zhang neal N.Xiong central South University of Forestry and Technology Changsha410004China School of Information Technology and Management Hunan University of Finance and EconomicsChangsha410205China Department of Mathematics and computer Science Northeastern State UniversityTahlequahOK74464USA

In recent years,with the development of machine learning and deep learning,it is possible to identify and even control crop diseases by using electronic devices instead of manual *** this paper,an image recognition method of citrus diseases based on deep learning is *** built a citrus image dataset including six common citrus *** deep learning network is used to train and learn these images,which can effectively identify and classify crop *** the experiment,we use MobileNetV2 model as the primary network and compare it with other network models in the aspect of speed,model size,*** show that our method reduces the prediction time consumption and model size while keeping a good classification ***,we discuss the significance of using MobileNetV2 to identify and classify agricultural diseases in mobile terminal,and put forward relevant suggestions.

关键词： Deep learning image classification citrus diseases agriculture science and technology

News Text Topic clustering Optimized Method Based on TF-IDF Algorithm on Spark

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computers, Materials & continua 2020年第1期62卷 217-231页

作者： Zhuo Zhou jiaohua Qin Xuyu Xiang Yun Tan Qiang Liu neal N.Xiong college of computer Science and Information Technology Central South University of Forestry&TechnologyChangsha410114China Department of Mathematics and computer Science Northeastern State UniversityOK74464USA

Due to the slow processing speed of text topic clustering in stand-alone architecture under the background of big data,this paper takes news text as the research object and proposes LDA text topic clustering algorithm based on Spark big data *** the TF-IDF(term frequency-inverse document frequency)algorithm under Spark is irreversible to word mapping,the mapped words indexes cannot be traced back to the original *** this paper,an optimized method is proposed that TF-IDF under Spark to ensure the text words can be ***,the text feature is extracted by the TF-IDF algorithm combined countVectorizer proposed in this paper,and then the features are inputted to the LDA(Latent Dirichlet Allocation)topic model for ***,the text topic clustering is *** results show that for large data samples,the processing speed of LDA topic model clustering has been improved based *** the same time,compared with the LDA topic model based on word frequency input,the model proposed in this paper has a reduction of perplexity.

关键词： News text topic clustering spark platform countvectorizer algorithm TF-IDF algorithm latent dirichlet allocation model

Numerical analysis of straight and curved underground pipeline performance after rehabilitation by cured-in-place method

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Underground Space 2020年第1期5卷 30-42页

作者： K.j.Shou c.c.Huang Department of civil Engineering Chung Hsing University250Kuo Kuang RoadTaichungTaiwanRepublic of China Department of Civil EngineeringChung Hsing University250Kuo Kuang RoadTaichungTaiwanRepublic of China

Underground pipelines are prone to damage by corrosion in Taiwan due to the humid climate and the aging and overuse of ***-dig technologies are necessary,as the cities in Taiwan are highly *** methods,including the cured-in-place pipe(cIPP)method,provide an alternative to the new no-dig installation methods,which are comparatively more *** this study,the numerical analysis software ABAQUS was used to simulate straight-line and curved underground pipelines damaged by *** calibration by small-scale physical modeling in the laboratory,numerical models were applied to the analysis of the mechanical behavior of straight-line and curved underground *** analyze the performance of the cIPP rehabilitation method,different scenarios for straight-line and curved pipelines were *** included before-and after-rehabilitation,different internal pressures and surface loading conditions,and different liner deformabilities and pipe-liner interface *** results suggest that the cIPP method can reinforce damaged pipes by reducing stress concentration and differential displacement near the corrosion ***,proper liner thickness,liner material properties,and pipe-liner interface strength are essential for well-designed cIPP rehabilitation.

关键词： Straight-line pipeline curved pipeline No-Dig Rehabilitation cured-in-place-pipe Soil-pipe interaction

Reactive wetting behaviors of Sn/cu systems: A molecular dynamics study

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Nano-Micro Letters 2010年第2期2卷 60-67页

作者： j.Y.Hsieh j.L.chen c.chen H.c.Lin S.S.Yang c.c.Hwang Department of Mechanical Engineering Ming Hsin University of Science and Technology Institute of Precision Mechatronic Engineering Ming Hsin University of Science and Technology Department of Mechanical Engineering Wu Feng Institute of Technology Department of Information Management Meiho Institute of Technology Department of Engineering Science National Cheng Kung University

Influences of temperature and Sn-cu droplet's composition on reactive wettings of cu(100), cu(110), and cu(111) surfaces were analyzed, by using molecular dynamics(MD) calculations. As a result, the spreading on cu(110)(cu(100)) has the fastest(slowest) wetting kinetics. A higher temperature or a diluter cu content in the Sn-cu alloy droplet results in a higher wettability. Moreover, this work has addressed a theory for positioning the interface separating the liquidus and solidus alloys in the spreading film to confirm the hypothesis that the reactive wetting will come to the end when the interface saturates with the temperature-dependent solidus weight fraction of cu.

关键词： Wetting Surface alloying Molecular dynamics Droplet

Alternative techniques for forecasting mineral commodity prices

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International journal of Mining Science and Technology 2018年第2期28卷 309-322页

作者： c.A.Tapia cortez S.Saydam j.coulton c.Sammut School of Mining Engineering UNSW Sydney UNSW Business School UNSW Sydney School of computer Science and Engineering UNSW Sydney

Forecasting mineral commodity(Mc) prices has been an important and difficult task traditionally addressed by econometric, stochastic-Gaussian and time series techniques. None of these techniques has proved suitable to represent the dynamic behavior and time related nature of Mc markets. chaos theory(cT) and machine learning(ML) techniques are able to represent the temporal relationships of variables and their evolution has been used separately to better understand and represent Mc markets. cT can determine a system's dynamics in the form of time delay and embedding dimension. However, this information has often been solely used to describe the system's behavior and not for *** to traditional techniques, ML has better performance for forecasting Mc prices, due to its capacity for finding patterns governing the system's dynamics. However, the rational nature of economic problems increases concerns regarding the use of hidden patterns for forecasting. Therefore, it is uncertain if variables selected and hidden patterns found by ML can represent the economic *** their refined features for representing system dynamics, the separate use of either cT or ML does not provide the expected realistic accuracy. By itself, neither cT nor ML are able to identify the main variables affecting systems, recognize the relation and influence of variables though time, and discover hidden patterns governing systems evolution simultaneously. This paper discusses the necessity to adapt and combine cT and ML to obtain a more realistic representation of Mc market behavior to forecast long-term price trends.

关键词： Price forecasting Mineral commodity Market dynamics chaos theory Machine learning

SOME NEW cLASSES OF ALMOST PERIODIc FUNcTIONS

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chinese Annals of Mathematics,Series B 1989年第2期10卷 200-213页

作者： c.j.F.UPTON University of Melbourne Parkville Victoria 3052 Australia

In this paper classes of almost periodic functions are formed whlch lie between those established by W. Stepanoff and by H. Burkill.

关键词： cLASSES everywhere adding proof whenever 妇功 false apply Lebesgue 即夕

LIV-4:A novel model for predicting transplant-free survival in critically ill cirrhotics

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World journal of Hepatology 2020年第6期12卷 298-311页

作者： christina c Lindenmeyer Gianina Flocco Vedha Sanghi Rocio Lopez Ahyoung j Kim Fadi Niyazi neal A Mehta Aanchal Kapoor William D carey Eduardo Mireles-cabodevila carlos Romero-Marrero Department of Gastroenterology Hepatology and NutritionCleveland ClinicClevelandOH 44195United States Department of Internal Medicine Cleveland ClinicClevelandOH 44195United States Department of Quantitative Health Sciences Cleveland ClinicClevelandOH 44106United States Department of critical care Medicine Cleveland ClinicClevelandOH 44195United States

BAcKGROUND critically ill patients with cirrhosis,particularly those with acute decompensation,have higher mortality rates in the intensive care unit(IcU)than patients without chronic liver *** of short-term mortality is important in order to identify patients at highest risk of *** of the currently available prognostic models have been widely accepted for use in cirrhotic patients in the IcU,perhaps due to complexity of calculation,or lack of universal variables readily available for these *** believe a survival model meeting these requirements can be developed,to guide therapeutic decision-making and contribute to cost-effective healthcare resource *** To identify markers that best identify likelihood of survival and to determine the performance of existing survival *** consecutive cirrhotic patients admitted to a United States quaternary care center IcU between 2008-2014 were included and comprised the training *** data and clinical laboratory test collected on admission to IcU were *** under the curve receiver operator characteristics(AUROc)analysis was performed to assess the value of various scores in predicting inhospital mortality.A new predictive model,the LIV-4 score,was developed using logistic regression analysis and validated in a cohort of patients admitted to the same institution between *** Of 436 patients,119(27.3%)died in the *** multivariate analysis,a combination of the natural logarithm of the bilirubin,prothrombin time,white blood cell count,and mean arterial pressure was found to most accurately predict in-hospital *** from the regression coefficients of the independent variables,a novel model to predict inpatient mortality was developed(the LIV-4 score)and performed with an AUROc of 0.86,compared to the Model for End-Stage Liver Disease,chronic Liver Failure-Sequential Organ Failure Assessment,and Royal Free Hospital Score,wh

关键词： Risk stratification Resource allocation Intensive care unit Acute-on-chronic liver failure Modeling Mortality

coating behavior and surface hardening of Pd_(77)cu_6Si_(17) thin film metallic glass on AZ31 magnesium alloy

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journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第12期14卷 898-905页

作者： X.H.DU Y.c.cHANG H.j.PEI B.Y.cHEN M.c.KUO j.c.HUANG School of Materials Sciences and Engineering Shenyang Aerospace University Department of Materials and Optoelectronic Science National Sun Yat-Sen University Department of Materials Engineering Kun Shan University

Pd77cu6Si17(PcS) thin film metallic glasses(TFMGs) with high glass forming ability and hardness were selected as a hard coating for improving the surface hardness of AZ31 magnesium alloy. Both microindentation and nanoindentation tests were conducted on specimens with various PcS film thicknesses from 30 to 2000 nm. The apparent hardness and the relative indentation depth(β) were integrated using a quantitative model. The interaction parameters involved and relative hardness values were extracted from iterative calculations. According to the results, surface hardness can be enhanced greatly by PcS TFMGs in the shallow region, followed by gradual decrease with increasing β ratio. In addition, specimens with thinner coatings(e.g., 200nm) showed greater substrate-film interaction and those with thick coatings(e.g., 2000nm) became prone to film cracking. The optimum TFMG coating thickness in this study was estimated to be around 200 nm.

关键词： Thin film metallic glass(TFMG) Magnesium alloy Sputtering process Nanoindentation coating thickness