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Shape-changing particles for locally resolved particle geometry in DEM simulations

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Particuology 2024年第6期89卷 185-190页

作者： Enric Illana Klidi Qyteti Maik Scharnowski Maximilian brömmer Siegmar Wirtz Viktor Scherer Institute of Energy Plant Technology Ruhr-University BochumBochumGermany

Taking into account the complex shape of particles in discrete element method (DEM) simulations of large-scale granular systems is computationally demanding due to the time-consuming contact detection algorithms for polyhedral particles. In this short communication, a novel approach that locally resolves the particle shapes where needed and uses a simplified representation elsewhere, to accelerate simulations without compromising accuracy, is presented. For this purpose, a method employing a smooth transition of the particle shape representation from analytical spheres to shape-resolving polyhedra is introduced in DEM. The feasibility and correct implementation of this approach are demonstrated through simulations of hopper discharge involving spherical and dodecahedral particles from a flat bottom silo or shaft kiln. The model capabilities, in terms of accuracy as well as reduction in computational effort, are quantified for a moving bed with continuous outflow.

关键词： Polyhedron Size change Shape change Locally resolved DEM

rising utilization of stable isotopes in tree rings for climate change and forest ecology

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Journal of Forestry research 2024年第1期35卷 103-116页

作者： ru Huang Chenxi Xu Jussi Grießinger Xiaoyu Feng Haifeng Zhu Achim bräuning National Institute of Natural Hazards Beijing 100085People’s Republic of China Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029People’s Republic of China CAS Center for Excellence in Life and Paleoenvironment Beijing 100044People’s Republic of China Institute of Geography Friedrich-Alexander-University of Erlangen-Nuremberg91058 ErlangenGermany State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101People’s Republic of China University of Chinese Academy of Sciences Beijing 100049People’s Republic of China

Analyses of stable isotopes(C,O,H)in tree rings are increasingly important cross-disciplinary *** rapid development in this field documented in an increasing number of publications requires a comprehensive *** study includes a bibliometric analysis-based review to better understand research trends in tree ring stable isotope ***,1475 publications were selected from the Web of Science Core Collection for *** findings are that:(1)numbers of annual publications and citations increased since *** 1974 to 1980,there were around two relevant publications per ***,from 2020 to 2022,this rose sharply to 109 publications per ***,average article citations were less than four per year before 1990,but were around four per article per year after 2000;(2)the major subjects using tree ring stable isotopes include forestry,geosciences,and environmental sciences,contributing to 42.5%of the total during 1974-2023;(3)the top three most productive institutions are the Chinese Academy of Sciences(423),the Swiss Federal Institute for Forest,Snow and Landscape research(227),and the University of Arizona(204).These achievements result from strong collaborations;(4)review papers,for example,(Dawson et al.,Annu rev Ecol Syst 33:507-559,2002)and(McCarroll and Loader,Quat Sci rev 23:771-801,2004),are among the most cited,with more than 1000 citations;(5)tree ring stable isotope studies mainly focus on climatology and ecology,with atmospheric CO_(2) one of the most popular *** 2010,precipitation and drought have received increasing *** on this analysis,the research stages,key findings,debated issues,limitations and direc-tions for future research are *** study serves as an important attempt to understand the progress on the use of stable isotopes in tree rings,providing scientific guid-ance for young researchers in this field.

关键词： Tree rings Stable isotopes Web of Science Bibliometric

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生物材料制作的用于再生药物的纺织复合结构

国际纺织导报 2015年第8期43卷 4-4,34页

作者： r.brünler M.Hild D.Aibibu r.Hund C.Cherif M.Jger T.Hanke 卢宏伟德累斯顿工业大学纺织机械和高性能材料技术研究所德累斯顿工业大学材料科学研究所马克思伯格曼生物材料中心

壳聚糖良好的生物相容性使它非常适用于制备再生药物中的细胞载体结构。德累斯顿工业大学纺织机械和高性能材料技术研究所已经成功通过纺织加工技术，高质、稳定地制备出具有优异的生物相容性的壳聚糖纤维。壳聚糖的骨引导效应和再吸收... 详细信息

壳聚糖良好的生物相容性使它非常适用于制备再生药物中的细胞载体结构。德累斯顿工业大学纺织机械和高性能材料技术研究所已经成功通过纺织加工技术，高质、稳定地制备出具有优异的生物相容性的壳聚糖纤维。壳聚糖的骨引导效应和再吸收能力使它在硬组织再生材料领域具有极大的吸引力。

关键词：纺织机械再生材料复合结构生物材料药物壳聚糖纤维生物相容性制作

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长寿命UHPFrC组合钢桥面板研究综述

交通运输工程学报 2024年第1期24卷 68-84页

作者：段兰袁翊竑王春生 brÜHWILEr Eugen 长安大学公路学院陕西西安710064 瑞士洛桑联邦理工学院结构维护与安全实验室沃州洛桑CH-1015

从三方面归纳与剖析了超高性能纤维增强水泥基(UHPFrC)复合材料组合钢桥面板的研究进展,包括强韧性组合层选材、界面传力机制与损伤累积机理、设计方法与工程应用;总结了纤维类型、纤维掺量对UHPFrC轴拉性能和抗弯性能的影响规律,确定... 详细信息

从三方面归纳与剖析了超高性能纤维增强水泥基(UHPFrC)复合材料组合钢桥面板的研究进展,包括强韧性组合层选材、界面传力机制与损伤累积机理、设计方法与工程应用;总结了纤维类型、纤维掺量对UHPFrC轴拉性能和抗弯性能的影响规律,确定了支撑组合钢桥面板结构分析的多种本构模型;对比分析了热连接、冷连接和混合连接组合界面设计方式的技术特点,归纳了胶粘界面、冷连接剪力键界面与混合连接界面的传力机理试验与理论研究成果;总结了基于冷连接设计理念的组合钢桥面板在合理构造、设计方法、规范规程与工程实践等方面的研究成果,并探讨了长寿命组合钢桥面板的创新与发展方向。研究结果表明:单一或混杂纤维的掺入综合提升了UHPFrC的应变强化能力、弯曲变形能力、抗断裂能力、裂缝宽度控制能力和抗疲劳性能,轴拉条件下UHPFrC三线型简化本构模型有力支撑了组合钢桥面板的设计计算,弹塑性损伤本构模型可描述不可逆疲劳损伤累积;验证了冷连接组合界面的增韧效果与可靠性,新型剪力键既可以提高组合效应,也能增韧UHPFrC层,混合连接界面具有降低界面局部应力集中、提高整体界面抗剪刚度、改善界面传力、提升施工效率等综合技术优势,内聚界面本构模型可实现冷连接界面损伤累积反演分析,界面损伤预测结果准确可靠;基于冷连接的UHPFrC组合钢桥面板可以有效提高钢桥面板的局部刚度,相关设计方法可支撑标准的编制与工程实践;应进一步提升UHPFrC的性价比和界面连接的高效性和可靠性,以支撑组合钢桥面板的长寿命、强韧性、轻量化、易维护、低能耗设计与建造。

关键词：桥梁工程长寿命 UHPFrC组合钢桥面板冷连接件组合界面设计准则免蒸养

Evaluation of a complex couplet care intervention in a neonatal intensive care unit:A mixed methods study protocol

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Pediatric Investigation 2024年第2期8卷 139-148页

作者： Michella Bjerregaard Anna Axelin Emma Louise Malchau Carlsen Hans Okkels Birk Ingrid Poulsen Patrick Palisz Thomas Kallemose Anne brødsgaard Department of Paediatric and Adolescent Medicine Copenhagen University Hospital Amager HvidovreHvidovreDenmark Department of Public Health Faculty of HealthResearch Unit for Nursing and HealthcareUniversity of AarhusAarhusDenmark Department of Nursing Science University of TurkuTurkuFinland Department of Clinical Medicine Faculty of Health and Medical ScienceUniversity of CopenhagenCopenhagenDenmark Department of Public Health Section of Health Service ResearchUniversity of CopenhagenCopenhagenDenmark Department of People and Technology Roskilde UniversityRoskildeDenmark Department of Clinical research Copenhagen University Hospital Amager HvidovreHvidovreDenmark Department of Gynaecology and Obstetrics Copenhagen University Hospital Amager HvidovreHvidovreDenmark

Background:Families with an infant in need of intensive care most often experience a harmful separation after *** is due to a division of medical specialties into neonatal care and maternal ***,a couplet care intervention is implemented for mother-infant dyads in a neonatal intensive care *** study protocol provides a comprehensive evaluation of the *** aim is to evaluate the effect and implementation of a complex couplet care intervention to promote zero separation between mother and ***:The couplet care intervention is a family-centered model of care,where treatment-requiring mother-infant dyads will be admitted together and receive couplet care by neonatal *** study adheres to the framework of the Medical research Council and will use a mixed methods embedded design comprising a quasi-experimental trial and a qualitative process ***,a health economic evaluation will be conducted to assess the cost-effectiveness of this complex couplet care ***:Separation of mother-infant dyads after birth has an adverse impact on family health and *** study protocol evaluates a complex couplet care *** this study,a first step is taken to help bridge the gap between current practices and a new care model to prevent the separation of mothers and their infants.

关键词： Complex interventions Couplet care Family-centered care Neonatology Zero separation

Analysis and Optimization of Operational and Pollutant Attributes of Diesel Engine with CNT-Infused Orange Peel Biodiesel-Diesel Blend Fuel

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Journal of Thermal Science 2024年第2期33卷 761-778页

作者： ranjeet rAI r.r.SAHOO Mechanical Engineering Department GLA UniversityMathura281406India Mechanical Engineering Department IIT(BHU)Varanasi221005India

The current study is performed to find sustainable solutions for the future of transportation and environmental *** conventional methods and experimental design table(L16 Orthogonal Array)techniques have been employed to examine and optimize a diesel-powered engine's operational and pollutant *** L16 Orthogonal Array is obtained through Taguchi's experimental design approach using Minitab 16 *** experimental design incorporated three control variables,namely engine speed,fuel type,and engine load,each with four *** operational parameters,namely brake thermal efficiency(BTE)and brake specific fuel consumption(BSFC),as well as the emission characteristics,including hydrocarbon(HC),carbon monoxide(CO),nitrogen oxide(NO),and smoke emissions,were acquired using the L16 orthogonal array(OA) and subsequently *** utilization of methodologies such as signal-to-noise(S/N) ratio and grey analysis was employed to determine the optimal operational state of the engine to achieve maximum performance while minimizing *** engine's ideal state of operation,in terms of BTE and BSFC,was determined to be at 75% engine load,1000 r/min engine speed,and using 10^(-4)(in vol) carbon nanotube incorporated 20% orange peel biodiesel(OPB20CNT100) blended fuel(A3-B1-C4).The study indicated that engine load significantly influenced BTE and BSFC,with 84.05% and 87.79% contribution factors,*** 25% engine load,1000 r/min,and OPB20CNT100 fuel(A1-B1-C4) CO,smoke,NO,and HC emissions were the *** load affects emissions the *** BSFC increased 3.10% and NO emissions 1.77%.BTE,CO,smoke,and HC emissions decreased by 1.9%,12.29%,47.05%,and 47.22%,respectively,at optimal operating conditions concerning diesel *** study shows that Taguchi-Grey's experimental design optimizes diesel engine operational and pollutant *** outcomes revealed that orange peel biodiesel infused with CNT can replace diesel fuel in a

关键词： Taguchi-Grey method OPB20CNT100 transesterification S/N ratio GrG HC CO and NO

Localized-states quantum confinement induced by roughness in CdMnTe/CdTe heterostructures grown on Si(111) substrates

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Journal of Semiconductors 2024年第9期45卷 28-35页

作者： Leonarde N.rodrigues Wesley F.Inoch Marcos L.F.Gomes Odilon D.D.Couto Jr. bráulio S.Archanjo Sukarno O.Ferreira Physics Department Federal University of ViçosaViçosa36570-900Minas GeraisBrazil Instituto de Física Gleb Wataghin Universidade Estadual de CampinasCampinas13083-859São PauloBrazil National Institute of Metrology Quality and Technology(Inmetro) Materials Metrology Division(DIMAT)Xerém2525-020Rio de JaneiroBrazil

This work shows that despite a lattice mismatch of almost 20%, CdMnTe/CdTe/CdMnTe heterostructures grown directly on Si(111) have surprisingly good optical emission properties. The investigated structures were grown by molecular beam epitaxy and characterized by scanning transmission electron microscopy, macro-and micro-photoluminescence. Low temperature macro-photoluminescence experiments indicate three emission bands which depend on the CdTe layer thickness and have different confinement characteristics. Temperature measurements reveal that the lower energy emission band (at 1.48 eV)is associated to defects and bound exciton states, while the main emission at 1.61 eV has a weak 2D character and the higher energy one at 1.71 eV has a well-defined (zero-dimensional, 0D) 0D nature. Micro-photoluminescence measurements show the existence of sharp and strongly circularly polarized (up to 40%) emission lines which can be related to the presence of Mn in the heterostructure. This result opens the possibility of producing photon sources with the typical spin control of the diluted magnetic semiconductors using the low-cost silicon technology.

关键词： CdMnTe/CdTe/CdMnTe heterostructure CdTe/CdMnTe quantum emitters quantum dot-like emission silicon(111)substrate

Stranched Internal Hernia revealed by Occlusion of the Large Libra: A Propos of a Case

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Case reports in Clinical Medicine 2024年第1期13卷 37-42页

作者： Abdoulaye Kanté Mamady Almami Kéita Idrissa Tounkara Drissa Ouattara bréhima Bengaly Souleymane Sanogo bréhima Togola Drissa Traoré Nouhoum Ongoiba General Surgery Department of The Kati-Mali reference Health Center Koulikoro Mali Service of Surgery “B” of The CHU Du Point G Faculty of Medicine and Odontostomatology Bamako Mali

The left para-duodenal internal hernia, whose origin is generally embryological, is a rare etiology of intestinal obstruction found mainly in young adults. We report here the case of acute intestinal obstruction by left para-duodenal internal hernia in a 36-year-old young man. It was a patient who consulted urgently for occlusive syndrome with cessation of materials and gases. Abdominal percussion noted abdominal tympanism and pre-hepatic dullness was preserved. The flow and icicle signs were negative. Palpation did not objectify hepatosplenomegaly and did not find any organomegaly either. On the other hand, she found an epigastric defense. The abdominal X-ray without preparation showed water levels that were wider than high, hail-like. We performed a median above and below umbilical laparotomy and intraoperatively, it was an internal hernia with incarceration of small loops in a voluminous left paraduodenal sac of 12 cm. They were not necrotic and quickly recolored after extrication. We resected the hernial sac and closed the hernial orifice with separate stitches with absorbable suture 0. The postoperative course was simple. The patient was discharged from the hospital on the 4th postoperative day. After 18 months of hindsight, he is doing well.

关键词： Paraduodenal Internal Hernia Occlusion Laparotomy

Kinematic analysis of flexible bipedal robotic systems

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 795-818页

作者： r.FAZEL A.M.SHAFEI S.r.NEKOO Department of Mechanical Engineering Shahid Bahonar University of KermanKerman ***Iran Departamento de Ingenieria de Sistemas y Automatica Escuela Técnica Superior de IngenieriaUniversidad de SevillaSeville 41092Spain

In spite of its intrinsic complexities,the passive gait of bipedal robots on a sloping ramp is a subject of interest for numerous *** distinguishes the present research from similar works is the consideration of flexibility in the constituent links of this type of robotic *** is not a far-fetched assumption because in the transient(impact)phase,due to the impulsive forces which are applied to the system,the likelihood of exciting the vibration modes increases ***,the human leg bones that are involved in walking are supported by viscoelastic muscles and ***,for achieving more exact results,it is essential to model the robot links with viscoelastic *** this end,the Gibbs-Appell formulation and Newton's kinematic impact law are used to derive the most general form of the system's dynamic equations in the swing and transient phases of *** most important issue in the passive walking motion of bipedal robots is the determination of the initial robot configuration with which the system could accomplish a periodic and stable gait solely under the effect of gravitational *** extremely unstable nature of the system studied in this paper and the vibrations caused by the impulsive forces induced by the impact of robot feet with the inclined surface are some of the very serious challenges encountered for achieving the above-mentioned *** overcome such challenges,an innovative method that uses a combination of the linearized equations of motion in the swing phase and the algebraic motion equations in the transition phase is presented in this paper to obtain an eigenvalue *** solving this problem,the suitable initial conditions that are necessary for the passive gait of this bipedal robot on a sloping surface are *** effects of the characteristic parameters of elastic links including the modulus of elasticity and the Kelvin-Voigt coefficient on the walking stability of this type of

关键词： bipedal robot flexible link swing phase transient phase eigenvalue problem Kelvin-Voigt coefficient