检索结果-南通市图书馆

Modelling erosion of a single rock block using a coupled CFD-DEM approach

journal of Rock Mechanics and Geotechnical Engineering 2023年第9期15卷 2375-2387页

作者： Penghua Teng Fredrik johansson j.gunnar i.hellström Division of Fluid and Experimental Mechanics Department of Engineering Sciences and MathematicsLuleåUniversity of TechnologyLuleåSE-97187Sweden Division of Soil and Rock Mechanics KTH Royal Institute of TechnologyStockholmSE-10044Sweden

Rock block removal is the prevalent physical mechanism for rock erosion and could affect the stability of dam foundations and *** this,understanding of block removal is still inadequate because of the complex interactions among block characteristics,hydraulic forces,and erosive processes acting on the ***,based on a previously conducted physical experiment of erosion of a single rock block,the removal processes of two different protruding blocks are represented by a coupled computational fluid dynamics-discrete element model(CFD-DEM)approach under varied flow ***,the blocks could be rotated with respect to the flow direction to consider the effect of the discontinuity orientation on the block removal *** results visualize the entire block removal *** simulations reproduce the effects of the discontinuity orientation on the critical flow velocity inducing block incipient motion and the trajectory of the block motion observed in the physical *** numerical results present a similar tendency of the critical velocities at different discontinuity orientations but have slightly lower *** trajectory of the block in the simulations fits well with the experimental *** relationship between the dimensionless critical shear stress and discontinuity orientation observed from the simulations shows that the effect of block protrusion becomes more dominant on the block incipient motion with the increase of relative protrusion *** our knowledge,this present study is the first attempt to use the coupled finite volume method(FVM)-DEM approach for modelling the interaction behavior between the block and the flowing water so that the block removal process can be reproduced and analyzed.

关键词： Rock erosion Block removal incipient motion Coupled CFD-DEM Critical shear stress

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Turbulent Modulation in Particulate Flow: A Review of Critical Variables

引用

Engineering（科研） 2015年第10期7卷 597-609页

作者： Ammar Saber T.Staffan Lundstrom j.gunnar i.he.lstrom Fluid and Experimental Mechanics Division Lulea University of TechnologyLuleaSweden Mechanical Engineering Department University of MosulMosulIraq

A review of the main mechanisms influencing turbulent modulation in the presence of spherical and non-spherical particles is presented. The review demonstrates the need for more numerical and experimental work with higher accuracy than obtained so far and the need to resolve the flow near the surface of particles with the aim to re-evaluate the quantitative effect of different parameters on turbulent modulation. The review reveals that non-spherical particles have more adverse effect on turbulence as compared to spherical ones, for the same ambient conditions.

关键词： Two Phase Flow Turbulent Modulation Non-Spherical Particle Stokes Number Particle Reynolds Number Length Scale Density Ratio

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Turbulence Modelling of a Single-Phase Flow Cyclone Gasifier

引用

Engineering（科研） 2017年第9期9卷 779-799页

作者： Pantea Hadi jafari j.gunnar i.he.lstrom B.Rikard Gebart Department of Engineering Sciences and Mathematics Division of Energy ScienceLulea University of TechnologyLuleaSweden Department of Engineering Sciences and Mathematics Division of Fluid and Experimental MechanicsLulea University of TechnologyLuleaSweden

The current work aims to make a foundation for an engineering design of a cyclone gasifier to be able not only to predict its flow field with a suitable accuracy but also to investigate a large number of design alternatives with limited computer resources. A good single-phase flow model that can form the basis in an Euler-Lagrange model for multi-phase flow is also necessary?for modelling the reacting flow inside a cyclone gasifier. The present paper provides an objective comparison between several popular turbulence modelling options including standard k-ε and SST with curvature corrections, SSG-RSM and LES Smagorinsky models, for the single-phase flow inside cyclone separators/gasifiers that can serve as a guide for further work on the reacting multi-phase flow inside cyclone gasifiers and similar devices. A detailed comparison between the models and experimental data for the mean velocity and fluctuating parts of the velocity profiles are presented. Furthermore, the capabilities of the turbulence models to capture the physical phenomena present in a cyclone gasifier that?affects the design process are investigated.

关键词： Cyclone Gasifier Turbulence Modelling Swirling Flow Pattern Secondary Flow

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Modelling Dam Break Evolution over a Wet Bed with Smoothed Particle Hydrodynamics: A Parameter Study

引用

Engineering（科研） 2015年第5期7卷 248-260页

作者： Patrick jonsson Par jonsen Patrik Andreasson T.Staffan Lundstrom j.gunnar i.he.lstrom Department of Engineering Sciences and Mathematics LuleåUniversity of TechnologyLuleaSweden

When investigating water flow in spillways and energy dissipation, it is important to know the behavior of the free surfaces. To capture the real dynamic behavior of the free surfaces is therefore crucial when performing simulations. Today, there is a lack in the possibility to model such phenomenon with traditional methods. hence, this work focuses on a parameter study for one alternative simulation tool available, namely the meshfree, Lagrangian particle method Smoothed Particle Hydrodynamics (SPH). The parameter study includes the choice of equation-of-state (EOS), the artificial viscosity constants, using a dynamic versus a static smoothing length, SPH particle spatial resolution and the finite element method (FEM) mesh scaling of the boundaries. The two dimensional SPheRiC Benchmark test case of dam break evolution over a wet bed was used for comparison and validation. The numerical results generally showed a tendency of the wave front to be ahead of the experimental results, i.e. to have a greater wave front velocity. The choice of EOS, FEM mesh scaling as well as using a dynamic or a static smoothing length showed little or no significant effect on the outcome, though the SPH particle resolution and the choice of artificial viscosity constants had a major impact. A high particle resolution increased the number of flow features resolved for both choices of artificial viscosity constants, but at the expense of increasing the mean error. Furthermore, setting the artificial viscosity constants equal to unity for the coarser cases resulted in a highly viscous and unphysical solution, and thus the relation between the artificial viscosity constants and the particle resolution and its impact on the behavior of the fluid needed to be further investigated.

关键词： SPH Dam Break Smoothed Particle Hydrodynamics

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Responses to faecal microbiota transplantation in female and male patients with irritable bowel syndrome

引用

World journal of Gastroenterology 2021年第18期27卷 2219-2237页

作者： Magdy El-Salhy Christina Casen jørgen Valeur Trygve Hausken jan gunnar Hatlebakk Department of Medicine Stord Helse-Fonna HospitalStord 5416Norway Department of Clinical Medicine University of BergenBergen 5020Norway National Centre for Functional Gastrointestinal Disorders Department of MedicineHaukeland University HospitalBergen 5020Norway Genetic Analysis AS Oslo 0485Norway Unger-Vetlesen institute Lovisenberg Diaconal HospitalOslo 0440Norway

BACKGROUND Faecal microbiota transplantation(FMT)seems to be a promising treatment for irritable bowel syndrome(iBS)*** Western countries(United States and Europe),there is a female predominance in iBS.A sex difference in the response to FMT has been reported recently in iBS *** To investigate whether there was a sex difference in the response to FMT in the iBS patients who were included in our previous randomized controlled trial of the efficacy of *** The study included 164 iBS patients who participated in our previous randomized controlled *** patients had moderate-to-severe iBS symptoms belonging to the iBS-D(diarrhoea-predominant),iBS-C(constipation-predominant)and iBSM(mixed)subtypes,and had not responded to the National institute for health and Care Excellence(NiCE)-modified *** belonged in three groups:placebo(own faeces),and active treated group(30-g or 60-g superdonor faeces).The patients completed the iBS severity scoring system(iBS-SSS),Fatigue Assessment Scale(FAS)and the iBS quality of life scale(iBS-QoL)questionnaires at the baseline and 2 wk,1 mo and 3 mo after *** also provided faecal samples at the baseline and 1 mo after *** faecal bacteria profile and dysbiosis were determined using the 16S rRNA gene polymerase chain reaction DNA amplification covering V3-V9;probe labelling by single nucleotide extension and signal *** levels of short-chain fatty acids(SCFAs)were determined by gas chromatography and flame *** There was no sex difference in the response to FMT either in the placebo group or active treated *** was no difference between females and males in either the placebo group or actively treated groups in the total score on the iBS-SSS,FAS or iBS-QoL,in dysbiosis,or in the faecal bacteria or SCFA ***,the response rate was significantly higher in females with diarrhoea-predominant(iBS-D)than that of males at 1 mo,and 3 mo after ***,iBS-SSS total

关键词： Dysbiosis Fatigue Microbiome Quality of life Short-chain fatty acids Superdonor

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Effects of virus infection on expression of cell cycle regulatory proteins in the unicellular marine algae Emiliania huxleyi

引用

Acta Oceanologica Sinica 2011年第4期30卷 89-95页

作者： LiU jingwen gunnar Bratbak ZheNG Tianling Runar Thyrhaug Bioengineering College of jimei University Xiamen 361021 China Department of Microbiology University of Bergen Bergen N-5020 Norway Key Laboratory of MOE for Coast and Wetland Ecosystem School of Life Sciences XiamenUniversity Xiamen 361005 China State Key Laboratory of Marine Environmental Sciences of Xiamen University Xiamen 361005 China

The authors have investigated the biochemical events by which marine algal virus infection induces cell cycle arrest. The key G 2 /M-phase regulatory proteins are analyzed by immunobloting in unicel-lular Emiliania huxleyi,suggesting that virus induced cell cycle arrest is related with virus＇s effect on cyclins and cyclin dependent kinases. E. huxleyi virus（EhV） represses Cdc2/cyclinB complex activity by inhibiting the activity of Cdc2 kinase in a phosphorylation-related manner,blocking host cells G 2 /M checkpoint. Dephosphorylated /inactive Cdc25C combined with up-regulation of Wee1 expression at early infect period appears to be important mechanisms by which EhV represses Cdc2/cyclinB complex activity that is required for entry into M phase. This study has allowed us to confirm that algal virus infection leads to selective activation or inhibition of certain cell-cycle factors,which may play a significant role in establishing a more efficient environment for viral gene expression and DNA replication.

关键词： marine algal virus cell cycle regulators expression Emiliania huxleyi

来源：

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

Bacterial community succession in response to dissolved organic matter released from live jellyfish

引用

journal of Oceanology and Limnology 2019年第4期37卷 1229-1244页

作者： HAO Wenjin WiCheLS Antje FUCHS Bernhardt TANG Xuexi GERDTS gunnar School of Life Science Nantong University Nantong 226019 China Department of Marine Ecology College of Marine Life Sciences Ocean University of China Qingdao 266000 China Alfred Wegener institute for Polar and Marine Research Biologische Anstalt Helgoland Helgoland 27498 Germany Max-Planck-institute for Marine Microbiology Department Molecular Ecology Celsiusstr. 1 Bremen 28359 Germany

jellyfish blooms have increased worldwide, and the outbreaks of jellyfish population not only affect the food web structures via voracious predation but also play an important role in the dynamics of nutrients and oxygen in planktonic food webs. However, it remains unclear whether specific carbon compounds released through jellyfish metabolic processes have the potential to shape bacterial community composition. Therefore, in this study, we aimed to investigate the compositional succession of the bacterioplankton community in response to the dissolved organic matter (DOM) released by the live Scyphomedusae Cyanea lamarckii and Chrysaora hysoscella collected from helgoland Roads of the North Sea. The bacterial community was significantly stimulated by the DOM released form live jellyfish and different dominant phylotypes were observed for these two Scyphomedusae species. Furthermore, the bacterial community structures in the different DOM sources, jellyfish-incubated media, Kabeltonne seawater, and artificial seawater (DOM-free) were significantly different, as revealed by automated ribosomal intergenic spacer analysis fingerprints. Catalyzed reporter deposition fluorescence in situ hybridization (CARD-FiSH) revealed a rapid species-specific shift in bacterial community composition. Gammaproteobacteria dominated the community instead of the Bacteroidetes community for C. lamarckii, whereas Gammaproteobacteria and Bacteroidetes dominated the community for C. hysoscella. The significant differences in the bacterial community composition and succession indicate that the components of the DOM released by jellyfish might differ with jellyfish species.

关键词： bacterial community structure bacterial community composition dissolved organic matter jellyfish automated rRNA intergenic spacer analysis (ARiSA) catalyzed reporter deposition fluorescence in situ hybridization (CARD-FiSH)

来源：

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

Key stakeholders’ perspectives on the ideal partnering culture in construction projects

引用

Frontiers of Engineering Management 2022年第2期9卷 312-325页

作者： gunnar j.LUHR Marian G.C.BOSCH-REKVELDT Mladen RADUjKOViC Alma Mater Europaea ECM 2000 MariborSlovenia Delft University of Technology 2600 AA DelftThe Netherlands

This paper examines the current state of project cultures in the German turnkey construction industry and the ideal project cultures in terms of partnering from the perspective of various key stakeholders(i.e.,investors,General Contractors,(Sub-)Contractors and Designers).To investigate the current and ideal cultures,data were gathered among the key stakeholders by means of a survey study with 72 respondents divided over 12 *** respondents rated the current and desired cultures by using the Organizational Culture Assessment instrument,which belongs to the Competing Values *** investigations show many similarities and differences between the stakeholder perspectives of the current and the idealized partnering project ***,the General Contractors desire more cooperative behaviors than the(Sub-)Contractors,and the investors desire more pronounced flexibility than the General *** stakeholders desire a cultural change from highly competitive behaviors toward more *** in terms of clear procedures or more flexibility are only desired by the *** both the current and an ideal partnering project culture enables academics and project managers to compare their actual project cultures to an ideal *** such an approach,academics and project managers could measure whether new tools or changes in resources affect their project cultures toward a partnering project culture.

关键词： project culture organisational culture partnering construction culture stakeholder perspectives German

来源：

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

hermiticity of Hamiltonian Matrix using the Fourier Basis Sets in Bond-Bond-Angle and Radau Coordinates

引用

Chinese journal of Chemical Physics 2016年第1期29卷 112-122,I0002页

作者：于德权黄鹤 gunnar Nyman 孙志刚中国科学院大连化学物理研究所分子反应动力学国家重点实验室大连116023 辽宁师范大学物理与电子技术学院大连116029 瑞典哥德堡大学化学学院哥德堡中国科学与技术大学量子信息与量子科技前沿协同创新中心合肥230026

in quantum calculations a transformed Hamiltonian is often used to avoid singularities in a certain basis set or to reduce computation time. We demonstrate for the Fourier basis set that the Hamiltonian can not be arbitrarily transformed. Otherwise, the Hamiltonian matrix becomes non-hermitian, which may lead to numerical problems. Methods for cor- rectly constructing the Hamiltonian operators are discussed. Specific examples involving the Fourier basis functions for a triatomic molecular Hamiltonian （j=0） in bond-bond angle and Radau coordinates are presented. For illustration, absorption spectra are calculated for the OC10 molecule using the time-dependent wavepacket method. Numerical results indicate that the non-hermiticity of the Hamiltonian matrix may also result from integration errors. The conclusion drawn here is generally useful for quantum calculation using basis expansion method using quadrature scheme.

关键词： Discrete variable representation hermiticity Time-dependent wavepacket method Absorption spectra

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

integrating Downstream Ecological, Social and Economic Effects of Hydropower to Hydraulic Modeling: A Review

引用

World journal of Mechanics 2023年第8期13卷 149-172页

作者： j. Bastian Höller Anders G. Andersson j. gunnar i. hellström Division of Fluid and Experimental Mechanics Department of Engineering Sciences and Mathematics Lule&#229 University of Technology Lule&#229 Sweden

Hydropower gains increasing importance as a steerable and controllable power source in a renewable energy mix and deregulated markets. Although hydropower produces fossil-free energy, it has a significant impact on the local environment. This review investigates the effects of flow alterations by hydropower on the downstream river system and the possibilities to integrate these effects into hydraulic modeling. The results show that various effects of flow regulation on the ecosystem, but also social and economic effects on related communities were observed in the last decades. The application of hydraulic models for investigations of ecological effects is common. Especially hydraulic effects and effects on fish were extensively modeled with the help of hydraulic 1D- and 2D-simulations. Current applications to investigate social and economic effects integrated into hydraulic modeling are meanwhile limited. Approaches to realizing this integration are presented. Further research on the economic valuation of ecosystems and integration of social and economic effects to hydraulic models is necessary to develop holistic tools to support decision-making on sustainable hydropower.

关键词： Sustainable Hydropower Hydraulic Simulation River Regulation Down-stream Effects integrated Modeling

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：