检索结果-南通市图书馆

Comparing two IBM implementations for the simulation of uniform packed beds

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2024年第3期86卷 1-12页

作者： Christian Gorges maximilian brommer Christin Velten Siegmar Wirtz Enric Illana Mahiques Viktor Scherer Katharina Zahringer Berend van Wachem Mechanical Process Engineering Otto-von-Guericke-Universitat MagdeburgUniversitatsplatz 239106MagdeburgGermany Department of Energy Plant Technology Ruhr-Universitat BochumUniversitatsstraBe 15044780BochumGermany Laboratory of Fluid Dynamics and Technical Flows Otto-von-Guericke-Universitat MagdeburgUniversitatsplatz 239106MagdeburgGermany

Nowadays,the design of fixed packed bed reactors still relies on empirical correlations,which,especially for small tube to particle diameter ratios,are mostly too inaccurate because of the presence of wall ***,the simulation of fixed packed bed reactors plays an important role to predict and control the flow and process parameters in such,nowadays and in the *** of its straightforward applicability to non-uniform packings with particles of arbitrary shapes,the immersed boundary method(IBM)has advantages over other numerical methods and is used more and more *** paper compares two approaches of IBMs for the simulation of fixed bed reactors with spherical shaped *** classic,smooth approach is compared to the straightforward to implement blocked-off method for velocity fields above the fixed bed for particle Reynolds numbers of 300 and *** from experimental inline PIV-measurements of the reactor to be simulated serve as a basis for *** good agreement with the experiment is found for both simulation methodologies with higher resolutions,considering the more stable flow at a particle Reynolds number of *** in the different IBM approaches occurred for the more unsteady flow at a particle Reynolds number of *** to the blocked-off method,the smooth IBM reflects the formation of additional jets and recirculation zones better right above the bed,though increasing the fluid mesh resolution improves the accuracy of the blocked-off ***,a more diffusive behaviour is found for the blocked-off simulations due to the stairstep representation,which is avoided by using interpolation stencils as in the smooth *** higher mesh refinement in the blocked-off IBM this effect can be reduced,but this also increases the computational effort.

关键词： Immersed boundary method Packed bed reactor Uniform particle packing

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

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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

Ab initio density response and local field factor of warm dense hydrogen

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Matter and Radiation at Extremes 2024年第5期9卷 48-67页

作者： Tobias Dornheim Sebastian Schwalbe Panagiotis Tolias maximilian P.Böhme Zhandos A.Moldabekov Jan Vorberger Center for Advanced Systems Understanding(CASUS) D-02826 GörlitzGermany Helmholtz-Zentrum Dresden-Rossendorf(HZDR) D-01328 DresdenGermany Space and Plasma Physics Royal Institute of Technology(KTH)Stockholm SE-10044Sweden Technische Universität Dresden D-01062 DresdenGermany

We present quasi-exact ab initio path integral Monte Carlo(PIMC)results for the partial static density responses and local field factors of hydrogen in the warm dense matter regime,from solid density conditions to the strongly compressed *** full dynamic treatment of electrons and protons on the same footing allows us to rigorously quantify both electronic and ionic exchange–correlation effects in the system,and to compare the results with those of earlier incomplete models such as the archetypal uniform electron gas or electrons in a fixed ion snapshot potential that do not take into account the interplay between the two *** full electronic density response is highly sensitive to electronic localization around the ions,and our results constitute unambiguous predictions for upcoming X-ray Thomson scattering experiments with hydrogen jets and fusion *** PIMC results are made freely available and can be used directly for a gamut of applications,including inertial confinement fusion calculations and the modeling of dense astrophysical ***,they constitute invaluable benchmark data for approximate but computationally less demanding approaches such as density functional theory or PIMC within the fixed-node approximation.

关键词： local incomplete rigorous

Determinant variables on the isotopic values of particulate organic matter in a neotropical floodplain

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2024年第4期42卷 1173-1185页

作者： Vinícius de ANDRADE URBANO Matheus maximilian RATZ SCOARIZE Gustavo HENRIQUE ZAIA ALVES Driele DELANIRA-SANTOS Marcela da SILVA CAETANO Evanilde BENEDITO Departamento de Biologia(DBI) Laboratório de Ecologia EnergéticaUniversidade Estadual de Maringá(UEM)Maringá87020-900Brasil Programa de Pós-graduação em Ecologia de Ambientes Aquáticos Continentais(PEA) Universidade Estadual de Maringá(UEM)Maringá87020-900Brasil Departamento de Biologia Geral Universidade Estadual de Ponta Grossa(UEPG)Campus UvaranasPonta Grossa 84030-900Brasil Australian Rivers Institute(ARI) Griffith UniversityNathan QLD 4111Australia

Particulate organic matter(POM)is an important energy source for aquatic consumers,understanding its origin and composition is essential for understanding the energetic dynamics of aquatic *** aim of this study was to analyze the relationship between POM and phytoplankton(isotopic values and chlorophyll concentration)and abiotic variables during dry and rainy *** was conducted in rivers and lagoons in the floodplain of the Upper Paraná*** found a greater difference in ^(δ13)C values of POM between sampling points than between seasons,indicating that the composition of regional sources influences the composition of POM more than dry and rainy *** addition,the concentration of chlorophyll during the dry season was positively correlated with ^(δ13)C values during that rainy ***,we found a relationship between factors limiting the growth of phytoplankton and ^(δ13)C values of POM,such as phosphate ions,indicating that variables that regulate phytoplankton growth tend to influence the composition of POM in river ***,maintaining the variables that regulate the phytoplankton community is of fundamental importance for the composition of POM,an important energy source in aquatic environments.

关键词： freshwater wetland stable isotopes food web subtropical environment

Beyond total mesorectal excision: The emerging role of minimally invasive surgery for locally advanced rectal cancer

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal Surgery 2024年第8期16卷 2382-2385页

作者： Davina Perini Francesca Cammelli maximilian Scheiterle Jacopo Martellucci Annamaria Di Bella Carlo Bergamini Paolo Prosperi Alessio Giordano Department of Emergency and Acceptance Emergency Surgery UnitCareggi University HospitalFirenze 50137Italy

Multivisceral resection and/or pelvic exenteration represents the only potential curative treatment for locally advanced rectal cancer(LARC);however,it poses significant technical challenges,which account for the high risk of morbidity and mortality associated with the *** complete histopathologic resection is the most important determinant of patient outcomes,LARC often requires an extended resection beyond the total mesorectal excision plane to obtain clear re-section *** an era when laparoscopic surgery and robot-assisted surgery are becoming commonplace,the optimal approach to extensive pelvic inter-ventions remains ***,acceptance of the suitability of mini-mally invasive surgery is slowly gaining ***,there is still a lack of evidence in the literature about minimally invasive approaches in multiple and extensive surgical resections,highlighting the need for research studies to explore,validate,and develop this *** editorial aims to provide a critical overview of the currently available applications and challenges of minimally invasive abdo-minopelvic surgery for ***,we discuss recent developments in the field of robotic surgery for LARC,with a specific focus on new innovations and emerging frontiers.

关键词： Robotic surgery Pelvic exenteration Multivisceral resection Rectal cancer Total mesorectal excision

A probe into the acid deposition mitigation path in China over the last four decades and beyond

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2024年第4期11卷 84-92页

作者： Qian Yu Xiaodong Ge Haotian Zheng Jia Xing Lei Duan Dongwei Lv Dian Ding Zhaoxin Dong Yisheng Sun Posch maximilian Danni Xie Yu Zhao Bin Zhao Shuxiao Wang Jan Mulder Thorj?rn Larssen Jiming Hao State Key Laboratory of Environmental Simulation and Pollution Control School of EnvironmentTsinghua University State Key Laboratory of Pollution Control &Resource Reuse and School of the Environment Nanjing University State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex School of EnvironmentTsinghua University International Institute for Applied System Analysis(IIASA) School of Land Engineering Chang'an University Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life Sciences Norwegian Institute for Water Research

China currently has the highest acid deposition globally, yet research on its status, impacts, causes and controls is lacking. Here, we compiled data and calculated critical loads regarding acid deposition. The results showed that the abatement measures in China have achieved a sharp decline in the emissions of acidifying pollutants and a continuous recovery of precipitation p H, despite the drastic growth in the economy and energy consumption. However, the risk of ecological acidification and eutrophication showed no significant decrease. With similar emission reductions, the decline in areas at risk of acidification in China(7.0%) lags behind those in Europe(20%) or the USA(15%). This was because, unlike Europe and the USA, China's abatement strategies primarily target air quality improvement rather than mitigating ecological impacts. Given that the area with the risk of eutrophication induced by nitrogen deposition remained at 13%of the country even under the scenario of achieving the dual targets of air quality and carbon dioxide mitigation in 2035, we explored an enhanced ammonia abatement pathway. With a further 27% reduction in ammonia by 2035, China could largely eliminate the impacts of acid deposition. This research serves as a valuable reference for China's future acid deposition control and for other nations facing similar challenges.

关键词： acid deposition critical loads acidification eutrophication ammonia abatement

Phenotypic plasticity of labile traits in the wild

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Current Zoology 2013年第4期59卷 485-505页

作者： Jon E. brommer Department of Biology University Hill 20014 University of Turku Finland ARONIA Research and Development Institute Novia Applied University and Abo Akademi University Raseborgsvaigen 9 10600 Ekenas Finland

Individual-based studies allow quantification ofphenotypic plasticity in behavioural, life-history and other labile traits The study of phenotypic plasticity in the wild can shed new light on the ultimate objectives （1） whether plasticity itself can evolve or is constrained by its genetic architecture, and （2） whether plasticity is associated to other traits, including fitness （selection）. I describe the main statistical approach for how repeated records of individuals and a description of the environment （E） allow quantification of variation in plasticity across individuals （IxE） and genotypes （GxE） in wild populations. Based on a literature review of life-history and behavioural studies on plasticity in the wild, I discuss the present state of the two objectives listed above. Few studies have quantified GxE of labile traits in wild populations, and it is likely that power to detect statistically sig- nificant GxE is lacking. Apart from the issue of whether it is heritable, plasticity tends to correlate with average trait expression （not fully supported by the few genetic estimates available） and may thus be evolutionary constrained in this way. Individ- ual-specific estimates of plasticity tend to be related to other traits of the individual （including fitness）, but these analyses may be anti-conservative because they predominantly concern stats-on-stats. Despite the increased interest in plasticity in wild popula- tions, the putative lack of power to detect GxE in such populations hinders achieving general insights. I discuss possible steps to invigorate the field by moving away from simply testing for presence of GxE to analyses that ＇scale up＇ to population level proce-sses and by the development of new behavioural theory to identify quantitative genetic parameters which can be estimated

关键词： Individual-level plasticity Life history Animal personality Linear mixed model Animal model Wild population Longitudinal study

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

精英足球运动员教育、训练与人才培养路径

体育科研 2024年第3期45卷 11-19页

作者： Andreas Hohmann Dirk Mack maximilian Siener 张辉德国拜罗伊特大学拜罗伊特体育科学中心拜罗伊特95448 德国TSG霍芬海姆俱乐部(德甲)青年足球部辛斯海姆74889 浙江大学教育学院体育学系浙江杭州310058

儿童和青少年时期系统的足球训练,可以促进年轻足球运动员专项技能和专项体能的发展。旨在结合最新的研究成果、科学知识和应用实践,区分5岁到成年足球运动员的训练目标和方法,审视足球长期教育过程是否符合现代足球训练、运动表现和比... 详细信息

儿童和青少年时期系统的足球训练,可以促进年轻足球运动员专项技能和专项体能的发展。旨在结合最新的研究成果、科学知识和应用实践,区分5岁到成年足球运动员的训练目标和方法,审视足球长期教育过程是否符合现代足球训练、运动表现和比赛的要求。强调各个年龄组足球运动员应有特定的足球教育理念、训练目标和方法,这对青春期(U15和U17)及青春期后(U19和U21)的足球运动员尤其重要,因为他们必须准备并确保顺利过渡到精英足球运动员水平。

关键词：足球运动员教育与训练特定年龄组的训练目标与方法运动表现分析比赛形式

Reducing the loss of genetic diversity associated with assisted colonization-like introductions of animals

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2015年第5期61卷 827-834页

作者： Jaana KEKKONEN Jon E. brommer Department of Biosciences University of Helsinki Helsinki Finland Department of Biology University of Turku Turku Finland

Translocations, especially assisted colonizations, of animals are increasingly used as a conservation management tool. In many cases, however, limited funding and other logistic challenges limit the number of individuals available for transloeation. In conservation genetics, small populations are predicted to rapidly lose genetic diversity which can deteriorate population survival. Thus, how worried should we be about the loss of genetic diversity when introducing small, isolated populations？ Historical species introductions provide a means to assess these issues. Here we review 13 studies of ＂assisted colonization-like＂ introductions of animals, where only a small known number of founders established an isolated population without secondary contact to the source population. We test which factors could be important in retaining genetic diversity in these cases. In many cases, loss in heterozygosity （-12.1%） was detected, and more seriously the loss in allelic richness （-27.8 %）. Number of founders seemed to have an effect but it also indicated that high population growth rate could help to retain genetic diversity, i.e. future management actions could be effective even with a limited number of founders if population growth would be enhanced. On the contrary, translocated organisms with longer generation times did not seem to retain more genetic diversity. We advocate that, where possible, future studies on translocated animals should report the loss of genetic diversity （both heterozygosity and allelic richness）, which is essential for meta-analyses like this one for deepening our understanding of the genetic consequences of assisted colonization, and justifying management decisions [Current Zoology 61 （5）： 827-834, 2015].

关键词： Introduced species Loss of genetic diversity Number of founders Conservation management Population growth rate Generation time