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Structural Optimization of Metal and Polymer Ore Conveyor Belt Rollers

Computer Modeling in Engineering & Sciences 2022年第12期133卷 601-618页

作者： Joao Pedro Ceniz Rodrigo de Sá Martins marco antonio luersen Tiago Cousseau Department of Mechanical Engineering Federal University of Technology-Parana(UTFPR)Curitiba81280-340Brazil

Ore conveyor belt rollers operate in harsh environments,making them prone to premature *** service lives are highly dependent on the stress field and bearing misalignment angle,for which limit values are defined in a *** this work,an optimization methodology using metamodels based on radial basis functions is implemented to reduce themass of twomodels of *** a structural point of view,one of the rollers ismade completely of metal,while the other also has some components made of polymeric *** objective of this study is to develop and apply a parametric structural optimization methodology to minimize the mass of the two models of *** represent the mechanical behavior of the rollers,simulations were performed using the finite element *** the numerical optimization process,the variable parameters were the dimensions of the shaft and external *** geometric configuration that corresponded at the same time to the lowest mass and acceptable ranges for the stress and bearingmisalignment angle was *** the proposed methodology,a 32.3% reduction in mass was obtained for a metal roller design and an 18.9% reduction for a polymer *** both cases,the constraints were not *** the all-metal roller,the safety factors for the maximum stress and bearingmisalignment angle were 1.44 and 1.75,respectively,while for the polymer roller the corresponding figures were 1.50 and *** work describes a low-computational-cost optimization methodology for roller designs that have been little studied in the ***,the methodology could be adapted for use with other types of rollers and rollers made of different materials.

关键词： Conveyor belt rollers structural optimization surrogate models radial basis functions

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A Bidimensional Finite Element Study of Crack Propagation in Austempered Ductile Iron

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Computers, Materials & Continua 2023年第11期77卷 1411-1424页

作者： Gustavo von Zeska de França Roberto Luís de Assumpção marco antonio luersen Carlos Henrique da Silva Department of Mechanical Engineering Federal University of Technology–ParanáCuritiba81280-340Brazil

Austempered ductile iron(ADI)is composed of an ausferritic matrix with graphite nodules and has a wide range of applications because of its high mechanical strength,fatigue resistance,and wear resistance compared to other cast *** amount and size of the nodules can be controlled by the chemical composition and austenitizing *** the nodules have lower stiffness than the matrix and can act as stress concentrators,they influence crack ***,the crack propagation mechanism in ADI is not yet fully *** this study,we describe a numerical investigation of crack propagation in ADIs subjected to cyclic *** numerical model used to calculate the stress intensity factors in the material under the given conditions is built with the aid of Abaqus commercial finite element *** crack propagation routine,which is based on the Paris law,is implemented in *** results of the simulation show that the presence of a nodule generates a shear load on the crack ***,even under uniaxial tensile loading,the presence of the nodule yields a non-zero stress intensity factor in mode II,resulting in a deviation in the crack propagation *** is the primary factor responsible for changing the crack propagation direction towards the *** the parameters,for example,increasing the nodule size or decreasing the distance between the nodule and crack tip,can intensify this *** simulations comparing two different ADIs with the same graphite fraction area,the crack in the material with more nodules reaches another nodule in a shorter propagation time(or shorter number of cycles).This suggests that the high fatigue resistance observed in ADIs may be correlated with the number of nodules intercepted by a crack and the additional energy required to nucleate new *** summary,these findings contribute to a better understanding of crack propagation in ADIs,provide insights into the relationship between the presence

关键词： Austempered ductile iron(ADI) fatigue crack propagation graphite nodule

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A Finite Element Study of the Influence of Graphite Nodule Characteristics on a Subsurface Crack in a Ductile Cast Iron Matrix under a Contact Load

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Computer Modeling in Engineering & Sciences 2018年第10期117卷 59-71页

作者： Guilherme Suguinoshita Carlos Henrique da Silva marco antonio luersen Department of Mechanical Engineering Federal University of Technology-Parana(UTFPR)Rua Deputado Heitor Alencar Furtado5000CEP 81280-340CuritibaBrazil

This paper describes a study of the effects of graphite nodule characteristics on a subsurface crack in austempered ductile iron(ADI).A representative specimen of ADI,subjected to sliding contact load,is modeled using finite elements aiming to obtain the shear stress intensity factor(KII).The parameters varied were(i)the nodule diameter(two different values were considered),(ii)the distance between the nodule and the tip of the crack and(iii)the position of the load relative to the tip of the *** results of the numerical simulations show that the smaller diameter nodule has a larger influence on KII,suggesting a higher contact fatigue crack propagation rate in the material with the smaller *** results are the opposite of those observed in experimental studies and would appear to indicate that other factors should be also considered to ensure realistic estimates of the contact fatigue strength of ADI.

关键词： Austempered ductile iron subsurface crack stress intensity factor finite element analysis graphite nodule

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Influence of manufacturing process-induced geometrical defects on the energy absorption capacity of polymer lattice structures

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Defence Technology（防务技术） 2024年第5期35卷 47-59页

作者： Alexandre Riot Enrico Panettieri antonio Cosculluela marco Montemurro Universite de Bordeaux Arts et Metiers Institute of TechnologyCNRSINRABordeaux INPHESAM UniversiteI2M UMR 5295F-33405 TalenceFrance French Atomic Energy Commission Route des GargailsCedexF-33114Le BarpFrance

Modern additive manufacturing processes enable fabricating architected cellular materials of complex shape,which can be used for different *** them,lattice structures are increasingly used in applications requiring a compromise among lightness and suited mechanical properties,like improved energy absorption capacity and specific stiffness-to-weight and strength-to-weight ratios.A dedicated modeling strategy to assess the energy absorption capacity of lattice structures under uni-axial compression loading is presented in this *** numerical model is developed in a non-linear framework accounting for the strain rate effect on the mechanical responses of the lattice *** geometries,i.e.,cubic body centered cell,octet cell,rhombic-dodecahedron and truncated cuboctahedron 2+,are ***,the influence of the relative density of the representative volume element of each geometry,the strain-rate dependency of the bulk material and of the presence of the manufacturing process-induced geometrical imperfections on the energy absorption capacity of the lattice structure is *** main outcome of this study points out the importance of correctly integrating geometrical imperfections into the modeling strategy when shock absorption applications are aimed for.

关键词： Lattice structures Architected cellular materials Dynamic simulation Energy absorption Geometrical imperfection Additive manufacturing

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Climate change and human health: Last call to arms for us

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World Journal of Clinical Cases 2024年第11期12卷 1870-1874页

作者： antonio Corrente Maria Caterina Pace marco Fiore Department of Anaesthesiology and Intensive Care Medicine The Anastasia Guerriero HospitalMarcianise 81025CasertaItaly Department of Women Child and General and Specialized SurgeryUniversity of Campania“Luigi Vanvitelli”Naples 80138Italy

Climate change,now the foremost global health hazard,poses multifaceted challenges to human *** editorial elucidates the extensive impact of climate change on health,emphasising the increasing burden of diseases and the exacerbation of health *** highlights the critical role of the healthcare sector,particularly anaesthesia,in both contributing to and mitigating climate *** is a call to action for the medical community to recognise and respond to the health challenges posed by climate change.

关键词： Climate change Carbon footprint Sustainability Greenhouse gases Anaesthetic gases Environmental impact Disposable laryngoscope blades

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Frequency of and reasons behind non-listing in adult patients referred for liver transplantation: Results from a retrospective study

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World Journal of Transplantation 2024年第2期14卷 99-106页

作者： marco Biolato Luca Miele Giuseppe Marrone Claudia Tarli antonio Liguori Rosaria Calia Giovanni Addolorato Salvatore Agnes antonio Gasbarrini Maurizio Pompili antonio Grieco Department of Medical and Surgical Sciences CEMADFondazione Policlinico Universitario Agostino Gemelli IRCCSRome 00168Italy Department of Translational Medicine and Surgery Catholic University of Sacred HeartRome 00168Italy

BACKGROUND Few studies have evaluated the frequency of and the reasons behind the refusal of listing liver transplantation *** To assess the ineligibility rate for liver transplantation and its *** A single-center retrospective study was conducted on adult patients which entailed a formal multidisciplinary assessment for liver transplantation *** predictors for listing were evaluated using multivariable logistic *** In our center,314 patients underwent multidisciplinary work-up before liver transplantation enlisting over a three-year *** most frequent reasons for transplant evaluation were decompensated cirrhosis(51.6%)and hepatocellular carcinoma(35.7%).The non-listing rate was 53.8%and the transplant rate was 34.4%for the whole *** hundred and five motivations for ineligibility were *** most common contraindications were psychological(9.3%),cardiovascular(6.8%),and surgical(5.9%).Inappropriate or premature referral accounted for 76(37.1%)*** multivariable analysis,a referral from another hospital(OR:2.113;95%CI:1.259–3.548)served as an independent predictor of *** A non-listing decision occurred in half of our cohort and was based on an inappropriate or premature referral in one case out of *** referral from another hospital was taken as a strong predictor of non-listing.

关键词： Controindication Eligibility Evaluation Referral Personalized medicine

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Three predictive scores compared in a retrospective multicenter study of nonunion tibial shaft fracture

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World Journal of Orthopedics 2024年第6期15卷 560-569页

作者： Davide Quarta marco Grassi Giuliano Lattanzi antonio Pompilio Gigante Alessio D'Anca Domenico Potena Clinical Orthopedics Department of Clinical and Molecular ScienceUniversitàPolitecnica Delle MarcheAncona 60126Italy Department of Information and Engineering UniversitàPolitecnica delle MarcheAncona 60121Italy

BACKGROUND Delayed union,malunion,and nonunion are serious complications in the healing of *** the risk of nonunion before or after surgery is *** To compare the most prevalent predictive scores of nonunion used in clinical practice to determine the most accurate score for predicting *** We collected data from patients with tibial shaft fractures undergoing surgery from January 2016 to December 2020 in three different trauma *** this retrospective multicenter study,we considered only fractures treated with intramedullary *** calculated the tibia FRACTure prediction healING days(FRACTING)score,Nonunion Risk Determination score,and Leeds-Genoa Nonunion Index(LEG-NUI)score at the time of definitive *** Of the 130 patients enrolled,89(68.4%)healed within 9 months and were classified as *** remaining patients(n=41,31.5%)healed after more than 9 months or underwent other surgical procedures and were classified as *** calculation of the three scores,LEG-NUI and FRACTING were the most accurate at predicting *** LEG-NUI and FRACTING showed the best performances by accurately predicting union and nonunion.

关键词： Trauma Bone Tibial fracture Nonunion Scores Prediction model

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Modeling of recrystallization behaviour of AA6XXX aluminum alloy profile during extrusion process

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Transactions of Nonferrous Metals Society of China 2024年

作者： marco Negozio antonio Segatori Riccardo Pelaccia Barbara Reggiani Sara Di Donato Lorenzo Donati DIN Department of Industrial Engineering – University of Bologna University of Parma-Department of Engineering and Architecture Parco Area delle Scienze Hydro Innovation and Technology InterMech-MO.RE – University of Modena and Reggio Emilia DISMI Department of Sciences and Methods for Engineering University of Modena and Reggio Emilia

An innovative approach was introduced for the development of a AA6063 recrystallization model. This method incorporated a regression-based technique for the determination of material constants and introduced novel equations for assessing the grain size evolution. Calibration and validation of this methodology involved a combination of experimentally acquired microstructural data from the extrusion of three different AA6063 profiles and results from the simulation using the Qform Extrusion UK finite element code. The outcomes proved the agreement between experimental findings and numerical prediction of the microstructural evolution. The trend of the grain size variation based on different process parameters has been accurately simulated， both after dynamic and static recrystallization， with an error rate of less than 25% in almost the whole sampling computations.

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Mindfulness training in medical education as a means to improve resilience,empathy,and mental health in the medical profession

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World Journal of Psychiatry 2024年第4期14卷 489-493页

作者： Edison Iglesias de Oliveira Vidal Luiz Fernando Alvarenga Ribeiro marco antonio de Carvalho-Filho Fernanda Bono Fukushima Internal Medicine Department Botucatu Medical SchoolSao Paulo State University(UNESP)Botucatu 18618-687SPBrazil Wenckebach Institute for Education and Training LEARN-Lifelong LearningEducation and Assessment Research NetworkUniversity Medical Center GroningenGroningen 9713AVGroningenNetherlands Assertiva Mindfulness Botucatu 18603-970SPBrazil Surgical Specialties and Anesthesiology Department Botucatu Medical SchoolSão Paulo State University(UNESP)Botucatu 18618-687SPBrazil

The high rates of depression,burnout,and increased risk of suicide among medical students,residents,and physicians in comparison with other careers signal a mental health crisis within our *** contend that this crisis coupled with the inadequate acquisition of interpersonal skills during medical education results from the interaction between a challenging environment and the mental capital of ***,we posit that mindfulness-based practices are instrumental for the development of major components of mental capital,such as resilience,flexibility of mind,and learning skills,while also serving as a pathway to enhance empathy,compassion,self-awareness,conflict resolution,and relational ***,the evidence base supporting the effectiveness of mindfulness-based interventions has been increasing over the years,and a growing number of medical schools have already integrated mindfulness into their *** we acknowledge that mindfulness is not a panacea for all educational and mental health problems in this field,we argue that there is currently an unprecedented opportunity to gather momentum,spread and study mindfulness-based programs in medical schools around the world as a way to address some longstanding shortcomings of the medical profession and the health and educational systems upon which it is rooted.

关键词： Mindfulness Medical education Mental capital Mental health Medical students Resilience

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Treatment for paraganglioma with stereotactic radiotherapy

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World Journal of Clinical Cases 2024年第16期12卷 2729-2737页

作者： antonio Pontoriero Paola Critelli marco Zeppieri Filippo Flavio Angileri Tamara Ius Radiation Oncology Unit Department of BiomedicalDental Science and Morphological and Functional ImagesUniversity of MessinaMessina 98125Italy Department of Ophthalmology University Hospital of UdineUdine 33100Italy Neurosurgery Unit Department of BiomedicalDental Science and Morphological and Functional ImagesUniversity of MessinaMessina 98125Italy Neurosurgery Unit Head-Neck and NeuroScience DepartmentUniversity Hospital of UdineUdine 33100Italy

BACKGROUND Paragangliomas(PG)are rare neoplasms of neuroendocrine origin that tend to be highly vascularized,slow-growing,and usually *** date,common treatment options are surgical resection(SR),with or without radiation therapy(RT),and a watch-and-wait *** To evaluate the local control and effectiveness of exclusive fractionated stereotactic RT(FSRT)treatment in unresectable PG(uPG).METHODS We retrospectively evaluated patients with uPG(medically inoperable or refused SR)treated with FSRT with a Cyberknife System(Accuray Incorporated,Sunnyvale,California).Toxicity and initial efficacy were *** From May 2009 to January 2023,6 patients with a median age of 68(range 20-84)were treated with *** median delivered dose was 21 Gy(range 20-30 Gy)at a median isodose line of 75.5%(range 70%-76%)in 4 fractions(range 3-5 fractions).The median volume was 13.6 mL(range 12.4-65.24 mL).The median cumulative biological effective dose and equivalent dose in 2-Gy fractions were 70 Gy and 37.10 Gy *** of origin involved were the timpa-nojugular glomus(4/6),temporal bone,and cervical *** 1 of the 6 patients,the follow-up was insufficient;5 of 6 patients showed a 5-year overall survival and 5-year progression-free survival of 100%.We observed negligible toxicities during and after *** majority of patients showed stable symptoms during *** 1 patient developed spine *** Our preliminary results on this small cohort of patients suggest that FSRT could be an effective and safe alternative to SR.

关键词： Unresectable paraganglioma Fractionated stereotactic radiation therapy Cyberknife Neurosurgery Metastasis

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