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Assessment of k–ε models using tetrahedral grids to describe the turbulent flow field of a PBT impeller and validation through the PIV technique

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Chinese j.urnal of Chemical Engineering 2018年第5期26卷 942-956页

作者： victor X. Mendoza-Escamilla Alej.ndro Alonzo-Garcia Helvio R. Mollinedo Israel Gonzalez-Neria j. Antonio Yanez-Varela Sergio A. Martinez-Delgadillo Depto. Electronica Universidad Autonoma Metropolitana Azcapotzalco Av. San Pablo 180 Azcapotzalco CP 07740 Mexico D.F. Mexico CONACyT-Centro de Ingenierfa y Desarrollo Industrial Av. Piaya Pie de la Cuesta 702 Desarrollo San Pablo 76125 Queretaro Qro. Mexico UPIITA Instituto Politecnico Nacional Av. IPN 2580 G.A. Madero CP 07340 Mexico D.F. Mexico Depto. Ciencias Basicas Universidad Autonoma Metropolitana Azcapotzalco Av. San Pablo 180 Azcapotzalco CP 07740 Mexico D.F Mexico

In turbulence modeling, the RNG and Realizable models have important improvements in the turbulent production and dissipation terms in comparison to the Standard. The selection of the appropriate turbulence model has an impact on the convergence and solution in STRs, and they are used in mixing, multiphase modeling or as starting solution of transient models as DES and LES. Although there are several studies with the pitched blade turbine(PBT) impeller, most of them used the Standard model as representative of all k–ε models, using structured hexahedral grids composed of low number of cells, and in some cases under axial symmetry ***, in this work the assessment of the Standard, RNG and Realizable models to describe the turbulent flow field of this impeller, using the Multiple Reference Frame(MRF) and Sliding Mesh(SM) approaches with tetrahedral domains in dense grids, is presented. This kind of cell elements is especially suitable to reproduce complex geometries. Flow velocities and turbulent parameters were verified experimentally by PIV and torque measurements. The three models were capable of predicting fairly the pumping number, the power number based on torque, and velocities. Although the RNG improved the predictions of the turbulent kinetic energy and dissipation rate, the Realizable model presented better performance for both approaches. All models failed in the prediction of the total dissipation rate, and a dependence of its value on the number of cells for the MRF was found.

关键词： Tetrahedral grids PIV Turbulent flow k-ε models Stirred vessel

Aggregator Based RPL for an IoT-Fog Based Power Distribution System with 6LoWPAN

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China Communications 2020年第1期17卷 104-117页

作者： Rij. j.ckson Tom Suresh Sankaranarayanan victor Hugo C.de Albuquerque j.el j.P.C.Rodrigues CMR Institute of Technology Bengaluru 560037India SRM Institute of Science and Technology Chennai 603203India University of Fortaleza(Unifor) FortalezaCE 60811-905Brazil Federal University of Piaui Teresina-PI64049-550Brazil Instituto de Telecomunicacoes 1049-001 LisboaPortugal

Advanced Metering Infrastructure(AMI)forms an important part in Smart *** the data effectively from smart meters to the Edge/Fog node requires an efficient routing *** Protocol for Low Power Lossy Area Network(RPL)is a standard routing protocol for IPv6 over Low Power Personal Area Network(6LoWPAN).In a Power Distribution system all the smart meters together form 6LoWPAN *** communicate with the fog router,which acts as the 6LoWPAN *** was evaluated using Cooj. Network simulator for a power distribution network *** nodes which were far away from the fog node gave low Packet Delivery Ratio(PDR)and large End to End *** paper proposes an aggregation RPL scheme by modifying the existing Contiki *** smart meter nodes communicate to the aggregator,which communicates to the fog *** results show that the aggregation scheme has 35.6%increase in PDR,lesser hop count and 13.24%decrease in End to End delay on an average compared to existing RPL.

关键词： IoT 6LoWPAN RPL routing distribution automation smart grid fog computing

Influence of Weather Conditions on the Surface Morphology and Wetting Behaviour of Superhydrophobic Quaking Aspen Leaves

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American j.urnal of Plant Sciences 2013年第5期4卷 61-68页

作者： j. j. victor U. Erb Department of Materials Science and Engineering University of Toronto Toronto Canada.

The effects of different environmental conditions on the wetting properties and surface morphology of surperhydrophobic quaking aspen leaves harvested during the 2011 growth season are examined. During this particular season quaking aspen leaves were not able to retain their superhydrophobic properties and associated surface structure features as they have usually been able to do in other years. Representative scanning electron microscopy images and wetting property measurements of quaking aspen leaf surfaces harvested throughout this season are presented and discussed with the obj.ctive of linking weather induced environmental stresses that occurred in 2011 to the sudden and unusual reduction in non-wetting properties and drastic changes in leaf surface structure. Erosion and regeneration rates of leaf wax crystals and the impact that environmental factors can have on these are considered and used to explain the occurrence of these unexpected changes.

关键词： Quaking Aspen Leaves Superhydrophobic Surface Structure Wax Crystal Erosion/Regeneration Weather Conditions

Estimating potential harvestable biomass for bioenergy from sustainably managed private native forests in Southeast Queensland, Australia

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Forest Ecosystems 2018年第1期5卷 62-76页

作者： michael r.ngugi victor j.neldner sean ryan tom lewis j.aorong li phillip norman michelle mogilski department of environment and sciencequeensland herbariumMt Coot-tha RoadToowongQld 4066Australia private forestry service queensland 8 Fraser RdGympieQld 4570Australa department of agriculture and fisheries university of sunshine coastSippy DownsQld 4556Australia department of environment and science soil and land resources41 Boggo RoadDutton ParkQld 4102Australia university of queensland St LuciaQld 4072Australia

Background： Australia＇s energy future is at the crossroads and the role of renewable sources is in focus. Biomass from sustainably managed forests provide a significant opportunity for electricity and heat generation and production of liquid fuels. Australia has extensive native forests of which a significant proportion are on private land. However, there is limited knowledge on the potential capacity of this resource to contribute to the expansion of a biomass for bioenergy industry. In addition, there are concerns on how to reconcile biomass harvesting with environmental protection. Methods： We used regional ecosystem vegetation mapping for Queensland to stratify harvestable forests within the 1.8 m hectares of private native forests present in the Southeast Queensland bioregion in 2014. We used a dataset of 52,620 individual tree measurements from 541 forest inventory plots collected over the last 10 years. Tree biomass was estimated using current biomass allometric equations for Australia. Biomass potentially available from selective sawlog harvesting and silvicultural treatment across the bioregion was calculated and mapped. Results： Current sawlog harvesting extracts 41.4% of the standing tree biomass and a biomass for bioenergy harvest would retain on average 36% of felled tree biomass on site for the protection of environmental and fauna habitat values. The estimated area extent of harvestable private native forests in the bioregion in 2013 was 888,000 ha and estimated available biomass for bioenergy in living trees was 13.6 million tonnes （t）. The spotted gum （Corymbio citriodora subsp, variegata） forests were the most extensive, covering an area of 379,823 ha and with a biomass for bioenergy yield of 14.2 t-ha-1 （with approximately 11.2 ***-1 of the biomass harvested from silvicultural thinning and 3 ***-1 recovered from sawlog harvest residual）. Conclusions： Silvicultural treatment of private native forests in the Southeast Queensland bioregion, has the

关键词： Renewable energy Forest biomass Woody biomass Native forests Silvicultural management Biomassretention Biobased

Microwave-Assisted Au and Ag Nanoparticle Synthesis: An Energy Phase-Space Proj.ction Analysis

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American j.urnal of Analytical Chemistry 2023年第4期14卷 149-174页

作者： victor j. Law Denis P. Dowling School of Mechanical and Materials Engineering University College Dublin Dublin Ireland

Microwave-assisted synthesis of gold and silver nanoparticles, as a function of Green Chemistry, non Green Chemistry, and four applicator types are reported. The applicator types are Domestic microwave ovens, commercial temperature controlled microwave chemistry ovens (TCMC), digesters, and axial field helical antennae. For each of these microwave applicators the process energy budget where estimated (Watts multiplied by process time = kj. and energy density (applied energy divided by suspension volume = kj.ml-1) range between 180 ± 176.8 kj. and 79.5 ± 79 kj.ml-1, respectively. The axial field helical field an-tenna applicator is found to be the most energy efficient (0.253 kj.m-1 per kj. at 36 W). Followed by microwave ovens (4.47 ± 3.9 kj.ml-1 per 76.83 ± 39 kj., and TCMC ovens (2.86 ± 2.3 kj.m-1 per 343 ± 321.5 kj.. The digester applicators have the least energy efficiency (36.2 ± 50.7 kj.m-1 per 1010 ± 620 kj.. A comparison with reconstructed ‘non-thermal’ microwave oven inactivation microorganism experiments yields a power-law signature of n = 0.846 (R2 = 0.7923) four orders of magnitude. The paper provides a discussion on the Au and Ag nanoparticle chemistry and bio-chemistry synthesis aspects of the microwave applicator energy datasets and variation within each dataset. The visual and analytical approach within the energy phase-space proj.ction enables a nanoparticle synthesis route to be systematically characterized, and where changes to the synthesis are to be mapped and compared directly with historical datasets. In order to help identify lower cost nanoparticle synthesis, in addition to potentially reduce synthesis energy to routes informed changes to potentially reduce synthesis energy budget, along with nanoparticle morphology and yield.

关键词： Turkevich Microwave-Assisted Synthesis Ag Au Hydroxyapatite Nanoparticle Functionalization Energy Phase-Space Proj.ction

Microwave Detection, Disruption, and Inactivation of Microorganisms

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American j.urnal of Analytical Chemistry 2022年第4期13卷 135-161页

作者： victor j. Law Denis P. Dowling School of Mechanical and Materials Engineering University College Dublin Dublin Ireland

This paper reviews three complex interactions between microwave energy and microorganisms (bacteria, fungi, and viruses). The first interaction comprises the detection of viruses within human blood using a 50-Ohm transmission-line vector net-analyzer (typically 0 to 10 dBm @ 2 to 8.5 GHz) where the blood is placed within a test chamber that acts as a non-50-Ohm discontinuity. The second interaction employs 1 to 6.5 W @ 8 to 26 GHz for microwave feed-horn illumination to inactivate microorganisms at an applied power density of 10 to 100 mW-2. The third interaction is within multi-mode microwave ovens, where microorganism cell membrane disruption occurs at a few 100 s of W @ 2.45 GHz and microorganism inactivation between 300 to 1800 W @ 2.45 GHz. Within the first microwave interaction, blood relaxation processes are examined. Whereas in the latter two microwave interactions, the following disruption, and inactivation mechanisms are examined: chemical cellular lysis and, microwave resonant absorption causing cell wall rupture, and thermodynamic analysis in terms of process energy budget and suspension energy density. In addition, oven-specific parameters are discussed.

关键词： Bacteria Fungi Virus Hepatitis C Virus Human Immunodeficiency Virus Detection Disruption Inactivation N95 Respirator Microwave Oven

Microwave-Assisted Inactivation of Fomite-Microorganism Systems: Energy Phase-Space Proj.ction

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American j.urnal of Analytical Chemistry 2022年第7期13卷 255-276页

作者： victor j. Law Denis P. Dowling School of Mechanical and Materials Engineering University College Dublin Dublin Ireland

This paper describes the use of log-linear energy phase-space proj.ctions to analyze microwave-assisted inactivation of bacteria and viruses under different fomite conditions within multimode microwave ovens. The ovens are operated at a cavity-magnetron frequency of 2.45 ± 01 GHz. Porous fomites (moist face towels, cotton swabs, kitchen sponges, and scrubbing pads, cigarette filters and N95-like respirators);along with non-porous hard surface syringe fomites are studied. The fomites are classed as dielectric;and absorb microwave energy to varying degrees depending on their complex dielectric permittivity. Microorganism resilience to microwave stress (defined as ≥4 log10 reduction in inactivation) when mapped using iso-volume trend-lines in energy phase-space reveals the persistence imparted by the fomite, and can be mapped between different microwave ovens. Microorganism resilience to thermal microwave-assisted treatment increases from vegetative Gram-negative to vegetative Gram-positive and on to Gram-positive spores. Bacteriophage MS2 and influenza viruses have an intermediate resilience dependency. It is shown that linear-scaled fomite temperature against process time graphs can differentiate between non-thermal and thermal micro-wave-assisted treatment of microorganisms.

关键词： Bacteria MS2 Hepatitis C Virus Human Immunodeficiency Virus Influenza Virus Disruption Inactivation Microwave Oven Data Analysis

H pylori receptor MHC classⅡcontributes to the dynamic gastric epithelial apoptotic response

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World j.urnal of Gastroenterology 2006年第33期12卷 4689-4693页

作者： David A Bland Giovanni Suarez Ellen j.Beswick j.hanna C Sierra victor E Reyes the University of Texas Medical Branch at Galveston TX 77555-0366 United States

AIM： To investigate the role of MHC class Ⅱ in the modulation of gastric epithelial cell apoptosis induced by H pylori infection. METHODS： After stimulating a human gastric epithelial cell line with bacteria or agonist antibodies specific for MHC class Ⅱ and CD95, the quantitation of apoptotic and anti-apoptotic events, including caspase activation, BCL-2 activation, and FADD recruitment, was performed with a fluorometric assay, a cytometric bead array, and confocal microscopy, respectively. RESULTS： Pretreatment of N87 cells with the anti-MHC class ⅡIgM antibody RFD1 resulted in a reduction in global caspase activation at 24 h of H pylori infection. When caspase 3 activation was specifically measured, crosslinking of MHC class Ⅱ resulted in markedly reduced caspase activation, while simple ligation of MHC class Ⅱ did not. Crosslinking of MHC class Ⅱ also resulted in an increased activation of the anti-apoptosis molecule BCL-2 compared to simple ligation. Confocal microscope analysis demonstrated that the pretreatment of gastric epithelial cells with a crosslinking anti-MHC class Ⅱ IgM blocked the recruitment of FADD to the cell surface. CONCLUSION： The ability of MHC class Ⅱ to modulate gastric epithelial apoptosis is at least partially dependent on its crosslinking. The crosslinking of this molecule has anti-apoptotic effects during the earlier time points of Hpylori infection. This effect is possibly mediated by the ability of MHC class Ⅱ to modulate the activation of the pro-apoptotic receptor Fas by blocking the recruitment of the accessory molecule FADD, and this delay in apoptosis induction could allow for prolonged cytokine secretion by Hpylori-infected gastric epithelial cells.

关键词： Hpylori Epithelium Apoptosis Class Ⅱ MHC

Microwave-Assisted Transition Metal Nanostructure Synthesis: Power-Law Signature Verification

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American j.urnal of Analytical Chemistry 2023年第8期14卷 326-349页

作者： victor j. Law Denis P. Dowling School of Mechanical and Materials Engineering University College Dublin Dublin Ireland

A power-law (y = cxn) signature between process energy budget (kj. and process energy density (kj.ml-1) of microwave-assisted synthesis of silver and gold nanostructures has been recently described [Law and Denis. Aj.C, 14(4), 149-174, (2023)]. This study explores this relation further for palladium, platinum, and zinc oxide nanostructures. Parametric cluster analysis and statistical analysis is used to test the power-law signature of over four orders of magnitude as a function of six microwave applicator-types metal precursor, non-Green Chemistry synthesis and claimed Green Chemistry. It is found that for the claimed Green Chemistry, process energy budget ranges from 0.291 to 900 kj. with a residual error ranging between −33 to +25.9 kj.ml-1. The non-Green Chemistry synthesis has a higher process energy budget range from 3.2 kj.to 3.3 Mj. with a residual error of −33.3 to +245.3 kj.ml-1. It is also found that the energy profile over time produced by software controlled digestion applicators is poorly reported which leads to residual error problematic outliers that produce possible phase-transition in the power-law signature. The original Au and Ag database and new Pd, Pt and ZnO database (with and without problematic outliers) yield a global microwave-assisted synthesis power-law signature constants of c = 0.7172 ± 0.3214 kj.ml-1 at x-axes = 0.001 kj. and the exponent, n = 0.791 ± 0.055. The information in this study is aimed to understand variations in historical microwave-assisted synthesis processes, and develop new scale-out synthesis through process intensification.

关键词： Microwave-Assisted Synthesis Pd Ag Pt Au ZnO Power-Law Residual Error Statistical Analysis Parametric Cluster Analysis