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determination of the Normal Contact Stiffness and Integration Time Step for the Finite Element Modeling of Bristle-Surface Interaction

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Computers, Materials & Continua 2018年第7期56卷 169-184页

作者： Libardo V.Vanegas-Useche Magd M.Abdel-Wahab Graham A.Parker Facultad de ingeniería Mecánica Universidad Tecnológica de Pereira.Pereira 660003Colombia Division of Computational Mechanics Ton Duc Thang UniversityHo Chi Minh CityVietnam Faculty of civil Engineering Ton Duc Thang UniversityHo Chi Minh CityVietnam Soete Laboratory Faculty of Engineering and ArchitectureGhent UniversityTechnologiepark Zwijnaarde 903Zwijnaarde B-9052Belgium Faculty of Engineering and Physical Sciences University of Surrey.GuildfordUK

In finite element modeling of impact,it is necessary to define appropriate values of the normal contact stiffness,Kn,and the Integration Time Step(ITS).Because impacts are usually of very short duration,very small ITSs are ***,the selection of a suitable value of Kn is a critical issue,as the impact behavior depends dramatically on this *** this work,a number of experimental tests and finite element analyses have been performed in order to obtain an appropriate value of Kn for the interaction between a bristle of a gutter brush for road sweeping and a concrete ***,a suitable ITS is *** experiments consist of releasing a steel bristle that is placed vertically at a certain distance from a concrete surface and tracking the ***,in the finite element analyses,a beam is modeled in free fall and impacting a surface;contact and target elements are attached to the beam and the surface,*** results of the experiments and the modeling are integrated through the principle of conservation of energy,the principle of linear impulse and momentum,and Newton’s second *** results demonstrate that,for the case studied,Kn and the impact time tend to be independent of the velocity just before impact and that Kn has a very large variation,as concrete is a composite material with a rough ***,the ratio between the largest height of the bristle after impact and the initial height tends to be constant.

关键词： Brush street sweeping finite element modeling contact mechanics

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Reduction Kinetics of Uranium Trioxide to Uranium Dioxide Using Hydrogen

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World Journal of Nuclear Science and Technology 2015年第3期5卷 149-156页

作者： Pedro Orrego Alfaro José Hernández Torres Fernando Puchi Thiele Sección de Geología y Minería Departamento de Materiales Nucleares Comisión Chilena de Energía Nuclear Santiago Chile ingeniería civil Metalurgia Universidad Andrés Bello Santiago Chile

This article presents a study on the kinetics of the uranium conversion process, consisting in the reduction of uranium trioxide to uranium dioxide using hydrogen gas at temperatures of 500°C, 600°C and 700°C. Hydrogen concentrations used in the flow were 0.25 M, 0.50 M and 0.75 M. The mechanism established for the study of the kinetics of reduction of uranium trioxide was through the formation of an intermediate compound, U3O8. For this reason, these tests were divided into 2 stages: the first one the reduction from UO3 to U3O8, and second one from U3O8 to UO2. The results of each test were quantified by the release of H2O(g) produced by both reactions. Tests showed that the ideal working conditions are for hydrogen concentration flows of 0.75 M and temperatures in the range of 500°C - 600°C, with the intent to decrease the occurrence of side reactions that interfere with the process.

关键词： Conversion Uranium Oxides Nuclear Fuel Cycle

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Disinfection of Primary Municipal Wastewater Effluents Using Continuous UV and Ozone Treatment

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Journal of Water Resource and Protection 2014年第1期6卷 16-21页

作者： Yaneth Bustos Mabel Vaca Raymundo López Erick Bandala Luis Torres Neftalí Rojas-Valencia departamento de Energía Ciencias Básicas e Ingeniería Universidad Autónoma Metropolitana Azcapotzalco México departamento de ingeniería civil y Ambiental Universidad de las Américas Puebla. Sta. Catarina Mártir Cholula México Unidad Profesional Interdisciplinaria de Biotecnología Instituto Politécnico Nacional México D. F. México Universidad Nacional Autónoma de México Instituto de Ingeniería Coordinación de Ingeniería Ambiental México D. F. México

UV radiation and ozonation were investigated as disinfection alternatives for the wastewater treatment plant. The inactivation of total and fecal coliforms using ozone and ultraviolet radiation as separate treatments was evaluated. Different ozone concentrations (3 to 40 mg O3/L) were applied and UV fluencies ranging from 8.5 to 12 mJ/cm2 at different pH values (from 5 to 9) were tested. Best results were obtained for ozone doses near 20 mg/min with removals of 72% and 78% of fecal and total coliforms, respectively. The ozone also was capable of oxidizing organic matter in the effluent measured as COD (the highest removal obtained was 36% for 20 mg O3/min). Maximum bacterial resistance was observed at pH 7 in both cases. The UV light offered a high bacterial inactivation (over 80%) and the lowest bacterial inactivation was observed at pH 7. Finally, we obtained the electric energy per order (EEO, kWh/m3/order), defined as the electric energy (kW-h) required to degrade a contaminant by one order of magnitude in a unit volume of contaminated water, being noteworthy that EEO values for the UV process resulted were lower than those determined for the process with ozone in all the water flow tested.

关键词： Disinfection Ozone Treatment UV Treatment Wastewater

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The role of airborne particles and environmental considerations in the transmission of SARS-CoV-2

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Geoscience Frontiers 2021年第5期12卷 1-16页

作者： Longyi Shao Shuoyi Ge Tim Jones M.Santosh Luis F.O.Silva Yaxin Cao Marcos L.S.Oliveira Mengyuan Zhang Kelly BéruBé State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology(Beijing)Beijing 100083China College of Geoscience and Surveying Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Earth and Environmental Sciences Cardiff UniversityMuseum AvenueCardiffCF103YEUK School of Earth Sciences and Resources China University of Geosciences BeijingBeijing 100083China department of Earth Science University of AdelaideAdelaideSA 5005Australia department of civil and Environmental Universidad de la CostaCalle 58#55-66080002 BarranquillaAtlánticoColombia departamento de ingeniería civil y Arquitectura Universidad de LimaAvenida Javier Prado Este 4600-Santiago deSurco 1503Peru School of Biosciences Cardiff UniversityMuseum AvenueCardiff CF103AXWalesUK

Corona Virus Disease 2019(COVID-19)caused by the novel coronavirus,results in an acute respiratory condition coronavirus 2(SARS-CoV-2)and is highly *** recent spread of this virus has caused a global ***,the transmission routes of SARS-CoV-2 are being established,especially the role of environmental *** we review the environmental transmission routes and persistence of *** studies have established that the transmission of this virus may occur,amongst others,in the air,water,soil,cold-chain,biota,and surface *** has also been found that the survival potential of the SARS-CoV-2 virus is dependent on different environmental conditions and *** important pathways include aerosol and fecal *** matter may also be a carrier for *** microscopic particles can be easily absorbed by humans,more attention must be focused on the dissemination of these *** considerations are required to evolve a theoretical platform for epidemic control and to minimize the global threat from future epidemics.

关键词： Aerosol Airborne particles COVID-19 Environmental media SARS-CoV-2

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Numerical Analysis of Tilted Cutting and F128 Brushes

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Computer Modeling in Engineering & Sciences 2019年第10期121卷 23-47页

作者： Libardo V.Vanegas-Useche Magd M.Abdel-Wahab Graham A.Parker Facultad de ingeniería Mecánica Universidad Tecnológica de PereiraLa JulitaPereira 660003Colombia Division of Computational Mechanics Ton Duc Thang UniversityHo Chi Minh CityViet Nam Faculty of civil Engineering Ton Duc Thang UniversityHo Chi Minh CityViet Nam Soete Laboratory Faculty of Engineering and ArchitectureGhent UniversityTechnologiepark Zwijnaarde 46B-9052 ZwijnaardeBelgium Faculty of Engineering and Physical Sciences University of Surrey.Guildford GU27XHUK.

Road sweeping is an essential service that has to be conducted for public health,as well as aesthetic *** many countries,sweeping vehicles are used for this *** usually comprise a gutter brush that sweeps the debris that is located in the road *** work studies the performance of two kinds of gutter brushes:a cutting brush and a flicking(F128)*** is carried out by means of a 3-D dynamic,nonlinear Finite Element(FE)brush model developed by the *** this model,inertia forces are applied to the bristle,and its clamped end is ***,the surface(road)is rotated,translated,and ***-road interaction is modelled as flexible-to-rigid *** particular,the aim of this article is to compare the performance of a conventional brush and a brush rotating at variable *** brushes normally work tilted,FE analyses are carried out for tilted cutting and F128 brushes,rotating at speeds that fluctuate at different *** is concluded that brush oscillations have a significant effect on bristle tip velocities and bristle-road ***,at certain frequencies,oscillations seem to improve sweeping performance of the F128 ***,they do not appear to improve significantly the performance of the cutting brush.

关键词： Gutter brushes cutting brush flicking brush FEM variable speed brushing

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Research of multi-path routing based on network coding in space information networks

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Chinese Journal of Aeronautics 2014年第3期27卷 663-669页

作者： Yu Geng Zhong Congjiu Lan Xiaoyu Zhang Chi Wei Lina Liu Yansong department of civil Aviation Shenyang Aerospace University

A multi-path routing algorithm based on network coding is proposed for combating long propagation delay and high bit error rate of space information networks. On the basis of traditional multi-path routing, the algorithm uses a random linear network coding strategy to code data pack- ets. Code number is determined by the next hop link status and the number of current received packets sent by the upstream node together. The algorithm improves retransmission and cache mechanisms through using redundancy caused by network coding. Meanwhile, the algorithm also adopts the flow distribution strategy based on time delay to balance network load. Simulation results show that the proposed routing algorithm can effectively improve packet delivery rate, reduce packet delay, and enhance network performance.

关键词： Flow distribution Multi-path routing Network coding Retransmission Space information networks

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Assessment of Seismic Indirect Losses Based on Utility Curves

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Open Journal of civil Engineering 2019年第3期9卷 211-229页

作者： Jaime García-Pérez Eric García-López Instituto de ingeniería Ingeniería Estructural Edif. 2 Universidad Nacional Autónoma de México Ciudad Universitaria Coyoacán Mexico National Institute of Criminal Sciences Tlalpan Mexico

In the process of quantifying optimum seismic design parameters, the losses implying the failure of the system must be assessed. Intangibles such as human lives may lie among indirect losses. In this paper, we propose a model to calculate the value of the investment that society should be willing to make for saving lives. In order to do this, we analyze both individual and social problems. However, special treatment is given to the individual problem where the value of the life of a human being is inferred by what the person should be willing to pay or willing to accept to reduce the risk of dying. Due to the use of utility curves in the calculation of this kind of intangible, we pay special attention to shape and requirement conditions of these curves. We also pay attention when personal impact and legacies or bequests are considered in utility curves. The results are shown through some applications, especially in the computation of optimum seismic design coefficients at a low seismicity site.

关键词： Indirect Losses Human Life Value Willingness Criteria Utility Seismic design

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A charged star with geometric Karmarkar condition

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Communications in Theoretical Physics 2023年第8期75卷 139-149页

作者： Gabino Estevez-delgado Joaquin Estevez-delgado Rafael Soto-Espitia Antonio Rendón Romero Jorge Mauricio Paulin-Fuentes Facultad de Químico Farmacobiología de la Universidad Michoacana de San Nicolás de Hidalgo Facultad de Ciencias Físico Matemáticas de la Universidad Michoacana de San Nicolás de Hidalgo Edificio BCiudad Universitaria Facultad de ingeniería civil de la Universidad Michoacana de San Nicolás de Hidalgo Edificio A Ciudad Universitaria Facultad de ingeniería Mecánica de la Universidad Michoacana de San Nicolás de Hidalgo Edificio W Ciudad Universitaria División Académica de Ciencias Básicas de la Universidad Juárez Autónoma de Tabasco

In this paper,we analyse an analytical solution of the Einstein–Maxwell field equations that considers matter with anisotropic pressures in a static and spherically symmetric *** report the manner in which we obtained the solution,which is by means of the Karmarkar *** the model,we assume a state equation that describes the interaction of matter from quarks P=(c^(2)ρ-4B_(g))/3 and we consider the presence of electric charge,which can generate that the radial and tangential pressures are not *** a graphic manner,we analyse the physical properties of the model,taking as the observational data those of mass 1M⊙and radius7.69 km which were reported for the star Her *** charge values are found between 5.57×10^(18)C≤Q≤1.31×10^(20)C and the interval of the Bag constant Bg∈[118.7,122.13]MeV/fm^(3).Also,we show the stability of the configuration by means of the static stability criteria of Harrison–Zeldovich–Novikov((?M)/?ρc>0),as well as in regards to infinitesimal radial adiabatic perturbation,since the adiabatic indexγ>3.3 which guarantees the stability of the solution.

关键词： general relativity exact solutions anisotropic fluid Karmarkar condition

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Fused empirical mode decomposition and wavelets for locating combined damage in a truss-type structure through vibration analysis

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第9期14卷 615-630页

作者： Arturo GARCIA-PEREZ Juan P. AMEZQUITA-SANCHEZ Aurelio DOMINGUEZ-GONZALEZ Ramin SEDAGHATI Roque OSORNIO-RIOS Rene J. ROMERO-TRONCOSO HSPdigital-CA Telematica-Procesamiento Digital de Se ales DICIS Universidad de Guanajuato Carr. Salamanca-Valle km 3.5+1.8 Palo Blanco 36885 Salamanca Gto. Mexico HSPdigital CA Mecatronica Facultad de Ingeniería Campus San Juan del Río Universidad Autonoma de Queretaro Moctezuma 249 Col. San Cayetano 76807 San Juan del Río Qro. Mexico department of Mechanical and Industrial Engineering Concordia University1455 de Maisonneuve Boulevard West Montreal QC H3G 1M8 Canada

Structural health monitoring (SHM) is a relevant topic for civil systems and involves the monitoring, data processing and interpretation to evaluate the condition of a structure, in order to detect damage. In real structures, two or more sites or types of damage can be present at the same time. It has been shown that one kind of damaged condition can interfere with the detection of another kind of damage, leading to an incorrect assessment about the structure condition. Identifying combined damage on structures still represents a challenge for condition monitoring, because the reliable identification of a combined damaged condition is a difficult task. Thus, this work presents a fusion of methodologies, where a single wavelet-packet and the empirical mode decomposition (EMD) method are combined with artificial neural networks (ANNs) for the automated and online identification-location of single or multiple-combined damage in a scaled model of a five-bay truss-type structure. Results showed that the proposed methodology is very efficient and reliable for identifying and locating the three kinds of damage, as well as their combinations. Therefore, this methodology could be applied to detection-location of damage in real truss-type structures, which would help to improve the characteristics and life span of real structures.

关键词： Truss structure Vibration Spectral analysis Wavelet packet transform Empirical mode decomposition Artificialneural network (ANN)

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Flexural Performance of I-Joist Fabricated with Glue-Laminated Bamboo and <i>Gmelina arborea</i>Plywood

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Open Journal of civil Engineering 2014年第3期4卷 209-216页

作者： Viviana Paniagua Róger Moya Escuela de Arquitectura Universidad de Costa Rica Costa Rica Escuela de ingenieríaForestal Instituto Tecnológico de Costa Rica Cartago Costa Rica

The search for efficient and versatile structural elements, leads to the fabrication of I-joists (6.5 cm × 18.5 cm × 600 cm (width × depth × length) with glue-laminated bamboo (Guada angustifolia) in the flanges and Gmelina arborea 12-mm structural plywood in the web. The results showed a modulus of rupture (MOR) of 39.45 MPa and an effective modulus of elasticity (MOE) of 17.05 GPa. Shearing in the glue line was 5.95 MPa and the lamination strength was 6.45 MPa. Structural design values averaged 9.43 MPa for bending and 4.72 MPa in shear according to Costa Rican structural standards. Both resistance value (flexure and shear) were considered satisfactory for structural proposes and I-joists fabricated with bamboo and G. arborea plywood are comparable with the Andean classification group “C” structural grade. The use of this I-joist was also shown in roofing and flooring systems. This beam can be used in allowable spans from 2 to 4 m in span for flooring systems and from 5 to 7 m for roofing applications.

关键词： Guadua angustifolia Flexural Strength Shear Strength Plantation Wood Tropical Material

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