检索结果-南通市图书馆

Von Neumann Stability Analysis of DG-Like and PNPM-Like Schemes for PDEs with Globally Curl-Preserving Evolution of Vector Fields

引用

Communications on Applied Mathematics and Computation 2022年第3期4卷 945-985页

作者： Dinshaw S.Balsara roger Käppeli Physics and ACMS Departments University of Notre DameNotre DameINUSA Seminar for Applied Mathematics(SAM) Department of MathematicsETH ZürichCH-8092 ZurichSwitzerland

This paper examines a class of involution-constrained PDEs where some part of the PDE system evolves a vector field whose curl remains zero or grows in proportion to specified source *** PDEs are referred to as curl-free or curl-preserving,*** arise very frequently in equations for hyperelasticity and compressible multiphase flow,in certain formulations of general relativity and in the numerical solution of Schrödinger’s *** has shown that if nothing special is done to account for the curl-preserving vector field,it can blow up in a finite amount of simulation *** this paper,we catalogue a class of DG-like schemes for such *** retain the globally curl-free or curl-preserving constraints,the components of the vector field,as well as their higher moments,must be collocated at the edges of the *** are updated using potentials collocated at the vertices of the *** resulting schemes:(i)do not blow up even after very long integration times,(ii)do not need any special cleaning treatment,(iii)can oper-ate with large explicit timesteps,(iv)do not require the solution of an elliptic system and(v)can be extended to higher orders using DG-like *** methods rely on a spe-cial curl-preserving reconstruction and they also rely on multidimensional *** Galerkin projection,highly crucial to the design of a DG method,is now conducted at the edges of the mesh and yields a weak form update that uses potentials obtained at the verti-ces of the mesh with the help of a multidimensional Riemann solver.A von Neumann sta-bility analysis of the curl-preserving methods is conducted and the limiting CFL numbers of this entire family of methods are catalogued in this *** stability analysis confirms that with the increasing order of accuracy,our novel curl-free methods have superlative phase accuracy while substantially reducing *** also show that PNPM-like methods,which only evolve the lower moments while rec

关键词： PDEs Numerical schemes Mimetic Discontinuous Galerkin

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

Meta-analysis quantifying the potential of dietary additives and rumen modifiers for methane mitigation in ruminant production systems

引用

Animal Nutrition 2021年第4期7卷 1219-1230页

作者： Amelia K.Almeida roger SHegarty Annette Cowie School of Environmental and Rural Science University of New EnglandArmidaleNSW2351Australia NSW Department of Primary Industries Trevenna RdArmidaleNSW2351Australia

Increasingly countries are seeking to reduce emission of greenhouse gases from the agricultural industries,and livestock production in particular,as part of their climate change *** many reviews update progress in mitigation research,a quantitative assessment of the efficacy and performance-consequences of nutritional strategies to mitigate enteric methane(CH_(4))emissions from ruminants has been lacking.A meta-analysis was conducted based on 108 refereed papers from recent animal studies(2000-2020)to report effects on CH4 production,CH_(4) yield and CH_(4) emission intensity from 8 dietary *** interventions(oils,microalgae,nitrate,ionophores,protozoal control,phytochemicals,essential oils and 3-nitrooxypropanol).Of these,macroalgae and 3-nitrooxypropanol showed greatest efficacy in reducing CH_(4) yield(g CH_(4)/kg of dry matter intake)at the doses *** confidence intervals derived for the mitigation efficacies could be applied to estimate the potential to reduce national livestock emissions through the implementation of these dietary interventions.

关键词： Beef cattle Methane emissions abatement Dairy cattle Greenhouse gas Sheep

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

Nanoparticles based sensors for rapid detection of foodborne pathogens

引用

International Journal of Agricultural and Biological Engineering 2013年第1期6卷 28-35页

作者： Paul Chen Yanbin Li Tianhong Cui roger Ruan Department of Bioproducts and Biosystems Engineering University of Minnesota1390 Eckles Ave.St.PaulMN 55108 Department of Biological&Agricultural Engineering 203 Engineering HallUniversity of ArkansasFayettevilleAR 72701 Department of Mechanical Engineering University of Minnesota111 Church Street SEMinneapolisMN 55455 Department of Food Science and Nutrition University of Minnesota1390 Eckles Ave.St.PaulMN 55108

Rapid detection of foodborne pathogens is a key step in the control of food related *** methods for the detection of food pathogens,although typically sensitive,often require multiple time-consuming steps such as extraction,isolation,enrichment,counting,etc.,prior to measurement,resulting in testing times which can be *** is a need to develop rapid and sensitive detection *** review is intended to provide food scientists and engineers an overview of current rapid detection methods,a close look at the nanoparticles especially magnetic nanoparticle-antibody conjugates based methods,and identification of knowledge gaps and future research needs.

关键词： nano-sensor magnetic nano-particle food pathogens nuclear magnetic resonance

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

Physical and numerical modelling of the Severn Barrage

引用

Science China(Technological Sciences) 2014年第8期57卷 1471-1481页

作者： JAMES Brammer roger A Falconer CHRISTOPHER Ellis REZA Ahmadian Cardiff University the ParadeCardiff CF24 3AAUK School of Engineering Cardiff Universitythe ParadeCardiff CF24 3AAUK Arup 4 Pierhead StreetCardiff CF10 4QPUK

The Severn Estuary has one of the largest tidal ranges in the world and has long been the subject of consideration for tidal energy *** plans to build a tidal barrage across the estuary have existed in various forms since the 1920s,the 1989Severn Tidal Power Group(STPG)proposal is commonly referred to as the original Severn *** UK government abandoned this ebb generation scheme as a public investment project in ***,plans to build a two-way generation scheme were more recently put forward by a private consortium,namely Hafren *** assess the impact that a barrage would have on the hydro-environment in the estuary a number of numerical modelling studies have previously been conducted for the STPG *** this design has now been superseded by the Hafren Power proposal,new studies have been conducted to investigate the impact of a two-way *** this study the hydro-environmental impacts of both ebb-only and two-way schemes were assessed using physical and numerical modelling *** model barrages were constructed and testing was carried out using a physical model of the Severn Estuary,located in the hydraulics laboratory at Cardiff University.A depth integrated numerical model,namely DIVAST,was applied to the physical model geometry and modifications were made to simulate the effects of the barrage *** numerical model predictions showed good agreement with the corresponding laboratory *** results were consistent with conclusions from previous studies,relating to the ebb-only *** included an increase in the minimum water levels upstream of the barrage,a reduction in the mean water levels downstream of the barrage and a general reduction in tidal *** a two-way scheme changes in the tidal elevations and velocities depended on the exact operating conditions of the *** was found that with no starting head the tidal regime was similar to the natural state,with little change in the e

关键词： Severn Barrage numerical modelling physical modelling ebb generation two-way generation

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

Subsolidus Phase Relations in the System MgO-SiO_2-Cr-O and Thermodynamic Properties of Related Cr^(2+)-Containing End-members

引用

Acta Geologica Sinica(English Edition) 1996年第4期70卷 420-434页

作者： H.St.CO' Neill F.seifert Bayerisches Geoinstitut Universit t Bayreuth GermanyBayerisches Geoinstitut Universit t Bayreuth Germany

Subsolidus phase relations have been determined in the systems SiO2-Cr-O and MgO-SiO2-Cr-O in equilibrium with metallic Cr, at 1100 to 1500℃ and 0 to 2.88 GPa. The results show that there are no ternary phases in the SiO2-Cr-O system at these conditions, i.e., only the assemblage eskolaite-Cr-metal-quartz (or tridymite) is found. In the MgO-containing system, however, extensive substitution of Cr2+ for Mg is observed in (Mg, Cr2+)2SiO4 olivine, (Mg, Cr2+)2Si2O6 pyroxene, and (Mg, Cr2+)Cr2O4 spinel. Cr3+ levels in olivine and pyroxene are below detection limits. The pyroxene is orthohombic at XCrPx2+ 0.2. The experimental datahave been fitted to a thermodynamic model, and the authors obtained the mixing parameter (W) of Mg-Cr2+ in olivine, pyroxene and spinel, and the relation between temperatures and free energies of formation for the end-members: Cr2+-olivine (Cr2SiO4), Cr2+-pyroxene (Cr2Si2O6) and Cr2+-spinel (Cr3O4).

关键词： MgO-SiO_2-Cr-O system phase equilibrium thermodynamic properties

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

Contribution of Fluid Dynamics to Woodwind Instruments Investigations of Timbre and Pitch of Bassoon Bocals

引用

Journal of Thermal Science 2005年第3期14卷 264-266页

作者： roger GRUNDMANN Johannes BAUMGART Andreas RICHTER Hans KRüGER Technische Universitt Dresden Institute for Aerospace Engineering D-01062 Dresden Germany ProfessorTechnische Universitt Dresden Institute for Aerospace Engineering D-01062 Dresden GermanyTechnische Universitt Dresden Institute for Aerospace Engineering D-01062 Dresden GermanyTechnische Universit?t Dresden Institute for Aerospace Engineering D-01062 Dresden Germany

The discussed topic of isolating certain parameters which describe the timbre in connection with bocals of bassoons is of major interest for manufacturers and artist likewise since a reduction in the overall shear stress of these kinds of technical diffusors is very helpful but not sufficient. The timbre seen from the side of the musician has to be the same. Up to now two criteria have been isolated which have a deep influence on the easier blowing of the bassoon and on the comparable timbre due to geometrical reasons. If the geometrical outer contour is designed carefully, it is possible to modify the shape and preserve the timbre.

关键词： musical instrument bocal bassoon timbre principal component analysis

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

China＇s Roles in World History and Historiography

引用

Frontiers of History in China 2016年第2期11卷 177-246页

作者： roger Des Forges History Department University at Buffalo Buffalo NY 14260-4130 USA

Many historians of China and the world have long worked within certain paradigms that are increasingly recognized to be excessively Eurocentric, linear, and teleological. This article draws on both primary and secondary sources to propose a theory of Chinese history that is more sinocentric, cyclical, and open-ended. The theory takes seriously the well-known Chinese emphasis on establishing and maintaining cultural centrality and Chinese interest in learning from the past to influence the present and shape the future. It argues that these concerns have resulted in a spiral or helical pattern of Chinese historical development. It goes on to suggest that the Chinese spiral might help us to conceptualize world history in a way that respects all peoples of the world and all periods of history from the origins of our subspecies to the present. History is in one sense what actually happened in the past and historiography is how people interpret it to meet present needs and realize future aspirations. Given acceleration in the pace of change and expansion in the arena of action, historians can tell us little about what to expect in the future, but they may enhance the range of possibilities by bringing to light various past experiences. In this article I examine how the Chinese experience might assist us in fashioning a more peaceful, just, and sustainable world order.

关键词： Chinese history world history historiography centrality culture states

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

Two-step fast microwave-assisted pyrolysis of biomass for bio-oil production using microwave absorbent and HZSM-5 catalyst

引用

Journal of Environmental Sciences 2016年第7期28卷 240-247页

作者： Bo Zhang Zhaoping Zhong Qinglong Xie Shiyu Liu roger Ruan Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education Southeast University Center for Biorefining and Department of Bioproducts and Biosystems Engineering University of Minnesota

A novel technology of two-step fast microwave-assisted pyrolysis（f MAP） of corn stover for bio-oil production was investigated in the presence of microwave absorbent（Si C） and HZSM-5catalyst. Effects of f MAP temperature and catalyst-to-biomass ratio on bio-oil yield and chemical components were examined. The results showed that this technology, employing microwave, microwave absorbent and HZSM-5 catalyst, was effective and promising for biomass fast pyrolysis. The f MAP temperature of 500°C was considered the optimum condition for maximum yield and best quality of bio-oil. Besides, the bio-oil yield decreased linearly and the chemical components in bio-oil were improved sequentially with the increase of catalyst-to-biomass ratio from 1：100 to 1：20. The elemental compositions of bio-char were also determined. Additionally, compared to one-step f MAP process, two-step f MAP could promote the bio-oil quality with a smaller catalyst-to-biomass ratio.

关键词： Two-step Microwave Pyrolysis HZSM-5 zeolite catalyst Catalytic upgrading

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

Circle of Willis variants are not associated with thrombectomy outcomes

引用

Stroke & Vascular Neurology 2021年第2期6卷 310-313页

作者： Thomas seifert-Held Katharina Eberhard Soren Christensen Edith Hofer Christian Enzinger Gregory W Albers Maarten Lansberg Department of Neurology Medical University of GrazGrazAustria Core Facility Computational Bioanalytics Center for Medical ResearchMedical University of GrazGrazAustria Department of Neurology&Neurological Sciences Stanford UniversityStanfordCaliforniaUSA

Background The circle of Willis(COW)is part of the brain collateral *** absence of COW segments may affect functional outcome in patients with ischaemic stroke undergoing endovascular *** In 182 patients in the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution 2 Study and the CT Perfusion to Predict Response to Recanalisation in Ischaemic Stroke Project,COW anatomy was evaluated on postinterventional magnetic resonance *** absence of the posterior communicating artery or the first segments of posterior or anterior cerebral arteries ipsilateral to the ischaemic infarction was rated as an incomplete *** regression was applied to evaluate an association with the patients’modified Rankin scale(mRS)at 90 days after stroke Results An incomplete ipsilateral COW was not predictive of the patients’mRS at 90 days after *** associations were shown for the patients’baseline National Institutes of Health Stroke Scale(NIHSS),age and reperfusion *** effect size suggests that a significant association of an incomplete COW with the mRS at 90 days may be obtained in cohorts of more than 3000 *** Compared with the established predictors NIHSS,age and reperfusion status,an incomplete COW is not associated with functional outcome after endovascular therapy.

关键词： Willis anatomy incomplete

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

Skyline-join query processing in distributed databases

引用

Frontiers of Computer Science 2016年第2期10卷 330-352页

作者： Mei BAI Junchang XIN Guoren WANG roger ZIMMERMANN Xite WANG College of Information Science and Engineering Northeastern University Shenyang 110819 China School of Computing National University of Singapore Singapore 117417 Singapore

The skyline-join operator, as an important variant of skylines, plays an important role in multi-criteria decision making problems. However, as the data scale increases, previous methods of skyline-join queries cannot be applied to new applications. Therefore, in this paper, it is the first attempt to propose a scalable method to process skyline-join queries in distributed databases. First, a tailored distributed framework is presented to facilitate the computation of skyline-join queries. Second, the distributed skyline-join query algorithm （DSJQ） is designed to process skyline-join queries. DSJQ contains two phases. In the first phase, two filtering strategies are used to filter out unpromising tuples from the original tables. The remaining tuples are transmitted to the corresponding data nodes according a partition function, which can guarantee that the tuples with the same join value are transferred to the same node. In the second phase, we design a scheduling plan based on rotations to calculate the final skyline-join result. The scheduling plan can ensure that calculations are equally assigned to all the data nodes, and the calculations on each data node can be processed in parallel without creating a bottleneck node. Finally, the effectiveness of DSJQ is evaluated through a series of experiments.

关键词： skyline-join distributed filtering strategy scheduling plan rotation

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

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：