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Determination of contact parameters for discrete element method simulations of granular systems

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Particuology 2008年第6期6卷 521-528页

作者： Kevin francis Malone Institute of Particle Science and Engineering University of Leeds

Both linear-spring-dashpot （LSD） and non-linear Hertzian-spring-dashpot （HSD） contact models are commonly used for the calculation of contact forces in Discrete Element Method （DEM） simulations of granular systems. Despite the popularity of these models, determination of suitable values for the contact parameters of the simulated particles such as stiffness, damping coefficient, coefficient of restitution, and simulation time step, is not altogether obvious. In this work the relationships between these contact parameters for a model system where a particle impacts on a flat base are examined. Recommendations are made concerning the determination of these contact parameters for use in DEM simulations.

关键词： Discrete Element Method (DEM) Linear-spring--dashpot model Non-linear Hertzian-spring-dashpot model Contact parameters

Neutrino astronomy： An update

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Frontiers of physics 2013年第6期8卷 759-770页

作者： francis Halzen Wisconsin IceCube Particle Astrophysics Center (WIPAC) and Department of Physics University of Wisconsin Madison WI 53706 USA

Detecting neutrinos associated with the still enigmatic sources of cosmic rays has reached a new watershed with the completion of IceCube, the first detector with sensitivity to the anticipated fluxes. In this review, we will briefly revisit the rationale for constructing kilometer-scale neutrino detectors and summarize the status of the field.

关键词： neutrinos cosmic rays astrophysics

No country is an island in regulating food safety:How the WTO monitors Chinese food safety laws through the Trade Policy Review Mechanism(TPRM)

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Journal of Integrative Agriculture 2015年第11期14卷 2142-2156页

作者： francis Snyder Northwest A&F University School of Transnational Law Peking University Shenzhen Graduate School College of Europe

Established within the framework of the World Trade Organization （WTO）, the Trade Policy Review Mechanism （TPRM） reviews periodically the trade policies of all WTO Members. The review includes many aspects of food safety regulation. China＇s trade policy is reviewed every two years. This paper analyses in detail the reviews of China＇s trade policy in 2006, 2008, 2010, 2012 and 2014. It focuses in particular on food safety laws and types of standards, alignment of domestic standards with international standards, the role of different domestic institutions, transparency and notification of food safety measures under the WTO agreements on Sanitary and Phytosanitary Measures （SPS） and on Technical Barriers to Trade （TBTAgreement）, import and export, and geographical indications （GIs）. It concludes that the WTO TPRM can contribute, within its mandate, to reform of Chinese food safety laws and improvement of food safety in China. it notes that China has already undertaken substantial reforms of its system for regulating food safety. It recommends that China should continue to participate actively in the TPRM, follow its own path with regard to alignment and learn selectively from other WTO Members.

关键词： food safety food standards public health consumer welfare China Chinese food safety laws World Trade Organization WTO law Trade Policy Review Mechanism (TPRM) SPS Agreement TBT Agreement

Topological Studies of Three-dimensional Flows in a High Pressure Compressor Stator Blade Row without and with Boundary Layer Aspiration

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Chinese Journal of Aeronautics 2011年第5期24卷 541-549页

作者： Ankit SACHDEVA francis LEBOEUF Laboratoire de Mécanique des Fluides et d'Acoustique Ecole Centrale de Lyon

This paper presents a numerical study of the flow topologies of three-dimensional （3D） flows in a high pressure compressor stator blade row without and with boundary layer aspiration on the hub wall. The stator blade is representative of the first stage operating under transonic inlet conditions and the blade design encourages development of highly complex 3D flows. The blade has a small tip clearance. The computational fluid dynamics （CFD） studies show progressive increase of hub corner stall with the increase in incidence. Aspiration is implemented on the hub wall via a slot in the comer between the hub wall and the suction surface. The CFD studies show aspiration to be sensitive to the suction flow rate; lower rate leads to very complex flow struc- tures and increased level of losses whereas higher rate renders aspiration effective for control of hub comer separation. The flow topologies are studied by trace of skin friction lines on the walls. The nature of flow can be explained by the topological rules of closed separation. Furthermore, a deeper analysis is done for a particular case with advanced criterion to test the non-degeneracy of critical points in the flow field.

关键词： high pressure compressor flow topologies three-dimensional flows boundary layer aspiration tip clearance

Metamodeling and multicriteria analysis for sustainable and passive residential building refurbishment: A case study of French housing stock

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Building Simulation 2022年第3期15卷 453-472页

作者： Zaid Romani Abdeslam Draoui francis Allard LaRAT National School of Architecture of TetouanMorocco Team of Heat Transfer&Energetic FST of Tangier(UAE/U10FST) Abdelmalek Essaâdi UniversityMorocco LaSIE La Rochelle UniversityFrance

For the energy-related issues that the world is facing nowadays,the renovation of the building stock is one of the major *** objective of this study is to present an approach that helps to develop a multi-criteria decision support tool dedicated to the rehabilitation of sustainable and passive energy housing by integrating heating energy needs,economic,social and environmental criteria throughout the life cycle stages of the *** methodology consists of developing metamodels to predict heating energy needs from polynomial regression,design of experiments method and thermo-aeraulic simulations of building *** metamodel is used to carry out a combinatorial study of real technical *** methodology was applied to a real-life existing building located in La Rochelle city(France)based on an in-situ energy *** multicriteria analysis methods were studied and compared:weighted sum,Min-Max and Pareto ***,technical constraints as well as owner preferences and performance constraints have been *** technical solutions have been obtained in order to meet the various criteria *** addition,window shading and natural ventilation have been proposed to reduce the thermal discomfort rate in *** study was extended to all French ***,this method can be transformed into a decision support tool which will be useful for architects,engineers and stockholders.

关键词： metamodeling building refurbishment multi-criteria decision support sustainable building passive building

Climate Optimum rejuvenates the Mediterranean marine world

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Integrative Zoology 2010年第2期5卷 112-121页

作者： francis D.POR Department of Evolution Systematics and Ecology the National Collections of Natural HistoryHebrew University of JerusalemJerusalemIsrael

The Mediterranean,a sea with an already eventful history,is again undergoing an extreme change.A combination of general warming of the Mediterranean Sea and contact with the Indopacific world through the Suez Canal has set the stage for massive changes in the biota that inhabit this *** over a century,tropical species of all taxa have been migrating back into the Mediterranean,suggesting a duplication or restoration of a mid-Pliocene Piacenzian or late Miocene Tortonian *** cases are presented in three major *** is not a serial invasion by individual rogue exotic and damaging species,as often wrongly assumed and *** its unique biogeographic magnitude being recognized,an opportunity to study the progress of this phenomenon is being *** is because of the changed priorities in research,the acute taxonomic impediment and to the geopolitical difficulties in ***,the limitations of the restoration process are defined and a careful future outlook is presented.

关键词： climate optimum Lessepsian migration Mediterranean biota Tethys tropical restoration

Uncertainty, certainty, and relativity(Invited Paper)

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Chinese Optics Letters 2016年第1期14卷 2-6页

作者： francis T.S.Yu Department of Electrical Engineering Penn State University

One of the most fascinating principles in quantum mechanics must be Heisenberg＇s uncertainty principle, which can be briefly stated as follows： every physicM observation cannot be precisely determined without some degree of error or uncertainty. And it is by no means can one use the principle within the limit of certainty region, as will be shown in this Letter. Two of the most important pillars in modern physics must be Einstein＇s relativity theory and SchrSdinger＇s contribution to quantum mechanics. Yet, there is a profound connection between these discoveries by means of the uncertainty relationship, in which we shown that the observation of a high-speed object is conceivable if the speed of the observer keeps up with object＇s speed.

关键词： and relativity certainty Uncertainty

Greenhouse gas emissions during co-composting of cattle feedlot manure with construction and demolition （C＆D） waste

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Frontiers of Environmental Science & Engineering 2017年第3期11卷 141-152页

作者： Xiying Hao francis J. Larney Agriculture and Agri-Food Canada Lethbridge Research and Development Centre Lethbridge Alberta T1J 4B1 Canada

Manure management strategies should reflect current animal feeding practices and encourage recycling of organic waste to help protect our environment. This research investigated greenhouse gas （GHG） emissions during cattle manure stockpiling or composting with and without construction and demolition （C＆D） waste. Manure was collected from cattle fed a typical finishing diet （CK manure） and from cattle on diets which included 30% dried distillers grains with solubles （DG manure）. The CK and DG manures were co-composted with （4：1） C＆D waste （treatments： CK CD, DG CD）, composted alone （treatments： CK and DG） in 13 m3 bins or stockpiled without C＆D ~vaste （treatments： CK ST and DGST） for 99 days. Manure type （CK vs. DG manure） had no effect on GHG emissions-over the 99 day manure composting or stockpiling. Composting with C＆D waste 2 produced similar CO2 emissions, about double that from manure stockpthng （7.9 kgC.m^-2）. In contrast, CH4 emissions were reduced by the inclusion of C＆D waste （64 gC.m^-1 with C＆D vs. 244 gC.m 2 without C＆D） while the manure stockpile emitted the greatest amount of CH4 （464 gC. m 2）. Additionally, only 0.48% of C was emitted in CH4 form with C＆D waste, compared to 1.68% when composting without C＆D waste and 7.00% when cattle manure was stockpiled. The N2O emissions （12.4 to 18.0 gN.m ） were similar across all treatments. The lower CH4 emissions with C＆D waste are beneficial in reducing overall GHG emissions from manure composting, while reducing the amount of material entering landfills.

关键词： Livestock manuregreenhouse gas fluxstraw bale compost binN2O CH4 CO2

OpenStreetMap data quality enrichment through awareness raising and collective action tools——experiences from a European project

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Geo-Spatial Information Science 2018年第3期21卷 234-246页

作者： Amin Mobasheri Alexander Zipf Louise francis GIScience Research Group Institute of GeographyHeidelberg UniversityHeidelbergGermany Mapping for Change(Co.Ltd.) LondonUnited Kingdom

Nowadays,several research projects show interest in employing volunteered geographic information(VGI)to improve their systems through using up-to-date and detailed *** European project CAP4Access is one of the successful examples of such international-wide research projects that aims to improve the accessibility of people with restricted mobility using crowdsourced *** this project,OpenStreetMap(OSM)is used to extend OpenRouteService,a well-known routing ***,a basic challenge that this project tackled was the incompleteness of OSM data with regards to certain information that is required for wheelchair accessibility(*** information,kerb data,etc.).In this article,we present the results of initial assessment of sidewalk data in OSM at the beginning of the project as well as our approach in awareness raising and using tools for tagging accessibility data into OSM database for enriching the sidewalk data *** experiments have been carried out in different European cities,and discussion on the results of the experiments as well as the lessons learned are *** lessons learned provide recommendations that help in organizing better mapping party events in the *** conclude by reporting on how and to what extent the OSM sidewalk data completeness in these study areas have benefited from the mapping parties by the end of the project.

关键词： Accessibility OpenStreetMap(OSM) data quality data completeness sidewalk wheel map