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Challenges and opportunities in the production of magnesium parts by directed energy deposition processes

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Journal of Magnesium and Alloys 2024年第5期12卷 1663-1686页

作者： Gürel cam Ali Günen Iskenderun Technical University Faculty of Engineering and Natural SciencesDepartment of Mechanical Engineering31200 Iskenderun-HatayTurkey Iskenderun Technical University Faculty of Engineering and Natural SciencesDepartment of Metallurgy and Materials Engineering31200 Iskenderun-HatayTurkey

Mg-alloys have gained considerable attention in recent years for their outstanding properties such as lightweight,high specific strength,and corrosion resistance,making them attractive for applications in medical,aerospace,automotive,and other transport ***,their widespread application is hindered by their low formability at room temperature due to limited slip *** Mg-alloys have low mechanical properties due to the presence of casting defects such as porosity and anisotropy in addition to the high *** casting methods benefit from established process optimization techniques for these problems,additive manufacturing methods are increasingly replacing casting methods in Mg alloys as they provide more precise control over the microstructure and allow specific grain orientations,potentially enabling easier optimization of anisotropy properties in certain *** metal additive manufacturing(MAM)technology also results in some manufacturing defects such as inhomogeneous microstructural evolution and porosity and additively manufactured Mg alloy parts exhibit lower properties than the wrought parts,they in general exhibit superior properties than the cast ***,MAM is a promising technique to produce Mg alloy *** energy deposition processes,particularly wire arc directed energy deposition(WA-DED),have emerged as an advantageous additive manufacturing(AM)technique for metallic materials including magnesium alloys,offering advantages such as high deposition rates,improved material efficiency,and reduced production costs compared to subtractive ***,the inherent challenges associated with magnesium,such as its high reactivity and susceptibility to oxidation,pose unique hurdles in the application of this *** review paper delves into the progress made in the application of DED technology to Mg-alloys,its challenges,and ***,the predominant imperfections,notably inhomo

关键词： Additive manufacturing DED processes Arc-DED Wire arc additive manufacturing(WAAM) 3-D printing High deposition rate

A novel reusable anti-COVID-19 transparent face respirator with optimized airflow

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Bio-Design and Manufacturing 2021年第1期4卷 1-9页

作者： Hussain Alenezi Muhammet Emin cam Mohan Edirisinghe Department of Mechanical Engineering University College LondonTorrington PlaceLondon WC1E 7JEUK Department of Manufacturing Engineering College of Technological StudiesPAAET13092 Kuwait CityKuwait Center for Nanotechnology and Biomaterials Application and Research Marmara University34722 IstanbulTurkey

This novel face mask is designed to be a reusable respirator with a small and highly efficient disposable fabric *** material requirements are reduced by 75%compared to traditional designs and allow repeated cleaning or *** probability of virus particle inhalation is reduced using novel air filtration pathways,through square-waveform design to increase filter *** enters the mask from right and left side filters,while the area in front of the mouth is *** epoxy is used for a transparent frame,allowing lip-reading,and mask edges contain a silicone seal preventing bypass of the *** mask is manufactured using silicone molds,eliminating electricity requirements making it economical and viable in developing *** fluid dynamics numerical studies and Fluent ANSYS software were used to simulate airflow through the filter to optimize filter air path geometry and validate mask design with realistic human *** breathing cycle was represented as a transient function,and N95 filter specifications were selected as a porous *** novel design achieved 1.2×10^(−3) kg s^(−1),20%higher than human requirements,with air streamlines velocity indicating local high speed,forcing and trapping virus particles against filter walls through centrifugal forces.

关键词： COVID-19 Mask Prototype Flow Pressure Temperature

Hard carbon derived from coconut shells,walnut shells,and corn silk biomass waste exhibiting high capacity for Na-ion batteries

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Journal of Energy Chemistry 2021年第7期30卷 207-218页

作者： Cristina Nita Biao Zhang Joseph Dentzer camélia Matei Ghimbeu Universitéde Haute-Alsace Institut de Science des Matériaux de Mulhouse(IS2M)CNRS UMR 7361F-68100 MulhouseFrance Universitéde Strasbourg F-67081 StrasbourgFrance Center for Advanced Laser Technologies(CETAL) National Institute for LasersPlasma and Radiation PhysicsAtomistilor 409 bisRO-77125 MagureleRomania Department of Applied Physics The Hong Kong Polytechnic UniversityKowloonHong KongChina Réseau sur le Stockage Electrochimique de l’Energie(RS2E) CNRS FR345933 Rue Saint Leu80039 Amiens CedexFrance

In recent years,hard carbon materials have gained significant interest as anode materials for Na-ion *** waste is considered one of the most interesting,renewable,available,and cost-effective precursor to obtain hard carbon(HC);however,HC properties must be finely tuned to achieve performance comparable to those provided by Li-ion *** this work,three biomass wastes(coconut shells,walnut shells,and corn silk) were evaluated as potential precursors for HC preparation involving a pyrolysis process and subsequent acid washing to remove the inorganic *** obtained materials exhibited low and similar specific surface areas(lower amount of inorganic impurities and oxygen-based functional groups compared to the coconut shell and corn silk HCs,leading to higher initial coulombic efficiency(iCE).The structural organization was higher in the case of the walnut shell HC,while the corn silk HC revealed a heterogeneous structure combining both highly disordered carbon and localized graphitized *** HCs delivered high initial reversible capacities between 293 and 315 mAh g^(-1) at 50 mA g^(-1) current rate,which remained rather stable during long-term *** best capacity(293 mAh g^(-1) after 100 charge/discharge cycles) and highest capacity retention(93%) was achieved in walnut HCs in half-cells,which could be associated with its higher sp2 C content,better organized structure,and fewer *** "adsorption-insertion" Na storage mechanism is suggested based on several *** walnut HCs exhibited an attractive energy density of 279 Wh/kg when tested in full cells.

关键词： Biomass Pyrolysis Hard carbon Anode Na-ion batteries Energy storage

High Light Intensity Increases the cam Expression in “MD-2” Micro-Propagated Pineapple Plants at the End of the Acclimatization Stage

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American Journal of Plant Sciences 2015年第19期6卷 3109-3118页

作者： René C. rodríguez-Escriba Romelio rodríguez Dariel López Gustavo Y. lorente Yaima Pino Carlos E. Aragón Yolanda Garza Florencio E. Podestá Justo L. González-Olmedo Laboratorio de Agrobiología Centro de Bioplantas Universidad de Ciego de ávila Ciego de ávila Cuba Departamento Biotecnología Facultad Ciencias Químicas Universidad Autónoma de Coahuila Coahuila México Centro de Estudios Fotosintéticos y Bioquímicos Facultad de Ciencias Bioquímicas y Farmacéuticas Universidad Nacional de Rosario Rosario Argentina

This work describes the evaluation of morpho-physiological and biochemical changes in “MD-2” micro-propagated pineapple plants (Ananas comosus (L.) Merr.) grown after 30 days under low light intensity (LL, greenhouse light conditions at 250 μmol·m-2·s-1) or high light intensity (HL, field light conditions at 800 μmol·m-2·s-1). Gas exchange, leaf pH, protein content and superoxide dismutase activity (SOD) (EC 1.***.1.1) were measured every 3 h during one day. Chlorophylls content and succulence index (SI) were determined at 9 h. Results showed significant differences in CO2 exchange rates, with a maximum occurring at 6 h (3.00 and 8.25 μmol CO2 m-2·s-1 for leaves under LL and HL conditions respectively). Plants under HL conditions had higher CO2 uptake and lower pH values between 0 h and 6 h respective to LL plants. The maximum pH value was attained 3 h before in HL plants. Leaf SI was increased and chlorophyll content decreased by HL conditions. SOD activity was higher in plants under HL conditions, near doubling those of LL plants at 18 h (2.8 versus 1.5 U·mg-1 Protein respectively). Both groups showed a typical cam phenotype, but it was stronger in HL conditions, which may confer these plants with a better acclimation to transfer to the field.

关键词： Crassulacean Acid Metabolism Hardening Stage Ex Vitro Vitroplants Gaseous Exchange

Microstructure and mechanical properties of friction-stir welded St52 steel joints

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International Journal of Minerals,Metallurgy and Materials 2018年第12期25卷 1457-1464页

作者： Tevfik kucukomeroglu Semih M.Aktarer Guven Ipekoglu Gurel cam Department of Mechanical Engineering Karadeniz Technical UniversityTrabzon 61080Turkey Department of Automotive Technology Recep Tayyip Erdogan UniversityRize 53100Turkey Department of Mechanical Engineering Iskenderun Technical UniversityHatay 31200Turkey

The aim of this work is to investigate the mechanical properties and microstructures of friction-stir welded(FSWed) St52 structural steel joints. In this study, St52 steel plates with a thickness of 4 mm were butt-welded by friction-stir welding(FSW) using a tungsten carbide tool having a conical pin. The microstructure of the welded zone consists of equiaxed fine ferrite, grain boundary ferrite, Widmanstatten ferrite, and aggregates of ferrite + cementite. The microhardness measurements showed that the hardness of the welded zone was significantly higher than that of the base metal. The FSWed St52 joint exhibited a significant strength overmatching in the weld region and a strength performance similar to or slightly higher than that of the base plate.

关键词： friction-stir welding St52 steel microstructure mechanical properties

Evaluation of the Marginal Adaptation in Metal Crowns Using CAD/cam and Manual Wax Patterns

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Microscopy Research 2015年第2期3卷 26-32页

作者： Alan Sepulveda-rodríguez Felipe Guerrero-Martínez César Gaitan-Fonseca Takashi Komabayashi Enrique Reyes-Vela David Masuoka Department of Stomatology Universidad Autónoma de Aguascalientes Aguascalientes Mexico Faculty of Dentistry Universidad Autónoma de San Luis Potosí San Luis Potosí Mexico Department of Endodontics West Virginia University Charleston USA

The aim of this study is to evaluate the maximum and minimum distances between the model and the cast crown of three techniques using Scanning Electron Microscopy (SEM). Three technique groups were used for this study: group A (control), traditional manual wax patterns;group B, dipping wax patterns;group C, resin patterns made with CAD/cam. For each group, 10 samples were made using the same model, and then metal cast. Marginal accuracies of the samples were evaluated by performing gap measurements using SEM with a magnification of 1200× (minimum distance). The data were statistically analyzed using the one-way analysis of variance (ANOVA) at the 0.05 significance level. The average (standard deviation) of the minimum distance [μm] was 22.5 (12.1), 9.9 (4.3), and 14.7 (6.6), in groups A, B, and C, respectively. The average standard deviation of gap area [μm2] was 21667.2 (3476.4), 9906.4 (1512.1), and 16048.8 (8123). In the minimum distance comparison, groups A and B (p = 0.006) showed statistically significant results. In the gap area comparison, there was no statistical significance among groups A, B, and C (p = 0.174). The marginal adaptations of all three techniques were within a reported clinically acceptable range of margin.

关键词： Marginal Adaptation CAD/cam Metal Caps Wax Pattern

Determination of ^(210)Po and ^(210)Pb depositions in lichen and soil samples collected from K?prüba??-Manisa,Turkey

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Nuclear Science and Techniques 2018年第6期29卷 92-100页

作者： Sermin cam Kaynar Umit H. Kaynar Umran Hicsonmez Omer S. Sevinc Department of Physics Faculty of Sciences and Arts Manisa Celal Bayar University 45140 Manisa Turkey Science Education Faculty of Education Manisa Celal Bayar University 45900 Manisa Turkey Department of Chemistry Faculty of Sciences and ArtsManisa Celal Bayar University 45140 Manisa Turkey Primary School Science Teaching Duzce University81620 Manisa Turkey

üIn this study, we aimed to determine the accumulations of ^(210) Po and ^(210) Pb in soil and lichen samples in K? prü bas??. The K? prü bas?? district is home to the largest uranium deposits in Turkey. To date, there has been no study recorded in the literature related to ^(210) Po and ^(210) Pb depositions in lichens in K? prü bas??. Six different lichen species(Cladonia convoluta, Parmelina tiliacea, Physcia stellaris, Pleurosticta acetabulum, Xanthoparmelia conspersa, and Xanthoria parietina) as well as soil samples were collected from seven sampling locations around K? prü bas??. Lichens were used as biomonitors for ^(210) Po and ^(210) Pb deposition. The ^(210) Po and ^(210) Pb activity concentrations were measured in all the samples by alpha spectrometry. The activity concentrations in the lichen samples ranged from 64 to 577 Bq kg^(-1) with an average of 266 Bq kg^(-1) for ^(210) Po and from 78 to 565 Bq kg^(-1) with an average of 333 Bq kg^(-1) for ^(210) Pb. The activity ratios of ^(210) Po/ ^(210) Pb ranged from 0.80 to 1.99. In the lichen species,the mean ^(210) Po activity values varied from 154 Bq kg^(-1) in Pleurosticta acetabulum to 390 Bq kg^(-1) in Xanthoparmelia conspersa. The range of the mean ^(210) Pb activity was between 153 Bq kg^(-1) in Cladonia convoluta and 378 Bq kg^(-1) in Parmelina tiliacea. In the soil samples, ^(210) Po and ^(210) Pb activity concentrations were ranged from14 to 1268 Bq kg^(-1) and from 19 to 1113 Bq kg^(-1),respectively. While the values of ^(210) Po and ^(210) Pb measured in the lichen samples are comparable with those of the literature, the results of ^(210) Po and ^(210) Pb in the soil taken from the uranium mine are higher than the results of the literature studies.

关键词：土壤样品地衣种土耳其收集样品测量 alpha 平均数 Po

Examining the nonlinear and threshold effects of the 5Ds built environment to land values using interpretable machine learning models

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Journal of Geographical Sciences 2024年第12期34卷 2509-2533页

作者： Quang Cuong DOAN Khac Hung VU Thi Kieu Trang TRINH Thi cam Ngoc BUI Department of Urban Planning and Design The University of Hong KongHong KongChina Department of Land Management VNU University of ScienceHanoiVietnam Vietnam National University HanoiVietnam Faculty of Land Administration Hanoi University of Natural Resources and EnvironmentHanoiVietnam

Previous studies have extensively explored the critical influence of the built environment on land values,but the non-linear relationship has yet to be fully *** study aims to uncover the non-linear relationship between land values and the five built environment dimensions using machine learning algorithms and Shapley Additive ex Planation(SHAP).The results highlight that the Gradient Boost Decision Tree (GBDT) outperforms e Xtreme Gradient Boosting (XGBoost),Ordinary Least Squares (OLS),and Multiscale Geographically Weighted Regression (MGWR) in land value estimation,exhibiting higher R^(2) and lower Root Mean Square Error (RMSE) and Mean Absolute Error (MAE).The results illustrate that density and destination accessibility are the dominant factors,contributing 32.48%and37.38%to land value variation,*** observed that the top three factors affecting land values are the built-floor area ratio,the number of floors and the number of ***,the results revealed the non-linear relationship between the built environment and land values,suggesting that maintaining built environment features at optimal thresholds may increase land *** interaction effects may lead to bias in determining relationships between land values and the built *** study contributes to the literature by providing non-linear and threshold identification evidence in land value determinants,offering valuable insights for urban planners and real estate managers.

关键词： built environment land values housing price GBDT SHAP non-linear relationships machine learning

Cross-linked alginate edible coatings incorporated with hexyl acetate: Film characteristics and its application on fresh-cut rose apple

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Food Bioscience 2023年第2期52卷 759-767页

作者： Nhung Thi cam Duong Apiradee Uthairatanakij Natta Laohakunjit Pongphen Jitareerat Nattapon Kaisangsri Division of Postharvest Technology School of Bioresources and TechnologyKing Mongkut’s University of TechnologyThonburiThailand Division of Biochemical Technology School of Bioresources and TechnologyKing Mongkut’s University of TechnologyThonburiThailand Pilot Plant Development and Training Institute King Mongkut’s University of TechnologyThonburiThailand

Edible coatings,as carriers of antimicrobial compounds,have been proposed as an alternative method to preserve fresh-cut *** research focused to improve the shelf life of fresh-cut rose apples by applying an edible coating based on alginate cross-linked with calcium chloride(SAC)-enriched hexyl acetate(HA)as a natural antimicrobial *** SAC with HA in 0.01,0.03,and 0.05%(v/v)(SAC-HA)solution was evaluated for its film properties and applied to fresh-cut rose apples,and compared with the unmodified SAC *** quality and microbial contamination were determined every 2 days during 10 days of storage at 4℃.The film thickness,tensile strength,and elongation at break increased with the high concentrations of HA *** containing 0.03%HA had lower oxygen permeability(from 1.57 to 0.04×10^(-7) cm^(3)μm m^(-2) day^(-1) kPa^(-1)),as well as water vapor permeability(from 0.03 to 0.01 g mm m^(-2) day^(-1) kPa^(-1)),compared to the unmodified SAC ***,the greater coating uniformity and thickness were supported by scanning electron microscopy and Fourier transform infrared *** developed edible SAC coatings with 0.03%HA successfully preserved the physicochemical quality and extended the shelf life of fresh-cut rose apples for 10 days at 4℃ by retarding the respiration rate,inhibiting browning,and preventing microbial ***,the using of SAC-HA in fresh-cut products is a promising and safe preservation technique to extend shelf life.

关键词： Film properties Browning Antimicrobial Rose apple Postharvest quality