Journal articles on the topic 'Vol – Simulateurs'

ABSTRACTAcinetobacter baumanniihas emerged as a serious problematic pathogen due to the ever-increasing presence of antibiotic resistance, demonstrating a need for novel, broad-spectrum antimicrobial therapeutic options. Antimicrobial nanoemulsions are emulsified mixtures of detergent, oil, and water (droplet size, 100 to 800 nm) which have broad antimicrobial activity against bacteria, enveloped viruses, and fungi. Here, we screened the antimicrobial activities of five nanoemulsion preparations against fourAcinetobacter baumanniiisolates to identify the most suitable preparation for further evaluation. Among them, N5, which contains 10% (vol/vol) Triton X-100, 25% (vol/vol) soybean oil, and 1% (wt/vol) cetylpyridinium chloride (CPC), showed the best efficacy againstA. baumanniiin both its planktonic and biofilm forms and was selected for further study. Our data demonstrate that, while the killing of planktonic forms ofA. baumanniiwas due to the 1% CPC component of our nanoemulsions, the breakdown of biofilms was achieved via the emulsified oil and detergent fractions. Furthermore, we documented the effect of ethanol and NaCl in combination with N5 on planktonicA. baumannii. In killing curves of N5 combined with other agents (ethanol or NaCl), a synergistic effect of a ≥2-log decrease in CFU/ml was observed. The antibiofilm activity of N5 was confirmed via a cell proliferation test and scanning electron microscopy. The effects of exposure to severe environmental conditions, which simulates the field conditions in Iraq and Afghanistan, were evaluated, and this exposure did not affect the overall antimicrobial activity of N5. These studies lay a solid foundation for the utilization of nanoemulsions against the antibiotic-resistant forms ofA. baumannii.

Purpose:To develop a sailing ergometer that accurately simulates upwind sailing exercise.Methods:A sailing ergometer that measures roll moment accompanied by a biofeedback system that allows imposing a certain quasi-isometric upwind sailing protocol (ie, 18 bouts of 90-s hiking at constantly varying hiking intensity interspersed with 10 s to tack) was developed. Ten male high-level Laser sailors performed an incremental cycling test (ICT; ie, step protocol at 80 W + 40 W/3 min) and an upwind sailing test (UST). During both, heart rate (HR), oxygen uptake (VO2), ventilation (VE), respiratory-exchange ratio, and rating of perceived exertion were measured. During UST, also the difference between the required and produced hiking moment (HM) was calculated as error score (ES). HR, VO2, and VE were calculated relative to their peak values determined during ICT. After UST, the subjects were questioned about their opinion on the resemblance between this UST and real-time upwind sailing.Results:An average HM of 89.0% ± 2.2% HMmax and an average ES of 4.1% ± 1.8% HMmax were found. Mean HR, VO2, and VE were, respectively, 80% ± 4% HRpeak, 39.5% ± 4.5% VO2peak, and 30.3% ± 3.7% VEpeak. Both HM and cardiorespiratory values appear to be largely comparable to literature reports during on-water upwind sailing. Moreover, the subjects gave the upwind sailing ergometer a positive resemblance score.Conclusions:Results suggest that this ergometer accurately simulates on-water upwind sailing exercise. As such, this ergometer could be a great help in performance diagnostics and training follow-up.

Over 100 years after its discovery, Tobacco mosaic virus (TMV) remains an economically important pathogen for producers of many vegetatively propagated crops including petunias (Petunia × hybrida). To directly address this concern, we have developed a robust system to determine efficacy of disinfectants for treating TMV-contaminated cutting tools using a combination of preliminary screens and replicated trials. Contrary to widely held beliefs, wild-type (wt) TMV and four additional tobamovirus species infected four petunia cultivars without producing obvious viral symptoms. In contrast, a petunia isolate of TMV with 99.0% (nucleotide) and 99.4% (amino acid) coat protein sequence identity to wt TMV produced symptoms on all but one tested cultivar. We also show that TMV transmission can occur up to the twentieth petunia plant cut following a single cutting event on a TMV-infected plant. Although many new products are now available, treatment of TMV-contaminated tools with a 20% (wt/vol) solution of nonfat dry milk (NFDM) plus 0.1% Tween 20 or a 1:10 dilution of household bleach (0.6% sodium hypochlorite), two “old standbys”, completely eliminated TMV transmission to petunias. Treatment of contaminated tools with 1% (wt/vol) Virkon S or 20% NFDM also significantly reduced the incidence of infected petunias. Other treatments identified in the preliminary screens are candidates for the second phase of screening that simulates contamination during the process of taking cuttings.

Abstract. This article describes the volcanic effect of the Mt Pinatubo eruption in June 1991 on the ozone (O3) and methane (CH4) distribution in the stratosphere, as simulated with the chemistry–climate model EMAC (ECHAM/MESSy Atmospheric Chemistry: ECHAM5, version 5.3.02; MESSy, version 2.51). In this study, the effects of volcanic heating and heterogeneous chemistry on the chemical composition, caused by the volcanic aerosol, are separated. Global model simulations over the relevant period of the eruption from 1989 to 1997 with EMAC in T42L90MA resolution with specified dynamics and interactive chemistry were performed. The first simulation (VOL) contains the volcanic perturbation as an additional aerosol load and thus simulates the interaction of the aerosol with the chemistry and the radiation. The second simulation (NOVOL) neglects the eruption and represents the undisturbed atmosphere. In the third simulation (CVOL) the volcanic aerosol only interacts with the heterogeneous chemistry, such that volcanic heating is omitted. The differences between the simulation results VOL−NOVOL describe the total effect of the Mt Pinatubo eruption on the chemical composition, VOL−CVOL the stratospheric heating effect, and CVOL−NOVOL the chemical effect of the aerosol on the heterogeneous chemistry. The post-volcanic stratosphere shows a decrease in the O3 column in the tropics and an increase in the midlatitudes and polar regions, lasting roughly 1 year. This change in the ozone column is solely a result of the heating effect. The subsequent decrease in the ozone column is related to the chemical effect. The contribution of the catalytic loss cycles (NOx, HOx, ClOx, and BrOx) on the depletion of O3 is analysed in detail. In the tropics, CH4 increases in the upper stratosphere because of stronger vertical transport.

Marx's critique of capitalism remains foundational to the university social science curriculum yet little is known about how instructors teach Marx. In post-industrial, service-oriented economies, students are also increasingly disconnected from the conditions of industrial capitalism that animate Marx's analysis. Inspired by the discussion of how a piece of wood becomes a table in Marx's Capital Vol. 1., 'Our Table Factory, Inc.' simulates a diverse array of roles in the chain of production into and out of a table factory to understand key concepts: means/mode of production, use/exchange value, primitive accumulation wage/surplus labour, proletariat, bourgeoisie, alienation, false consciousness, commodity fetishism and communist revolution. We describe the exercise and present qualitative and quantitative assessment data from introductory sociology undergraduates across three small teaching-intensive universities in the United States. Findings detail the exercise's efficacy in fostering retention of material and in facilitating critical engagement with issues of inequality.

Using numerical simulation method, under the adiabatic condition, this paper simulates the of the upstream gas liquid two phase flow in main tube of hydraulic diameter 1 mm T tube. Superficial gas velocity within 0.01~30m/s and fluid velocity within 0.01~5m/s, under simulated by two kinds of gas volume fraction, air-water flow diagram and the flow pattern transition boundary have been got from the simulation. By comparing the simulation results, it shows that under the same environment, small channel volume fraction of gas has important influence on convection type transition boundaries.

Modeling is increasingly widely used to optimization, improvement and cost reduction efforts of the fuel cell technology. Although there are many computational models in literature that describe the behavior of Polymer Electrolyte Membrane (PEM) fuel cell, there is a only few models that simulates the catalyst surface concentration of reactant gases at the catalyst-membrane layer interface. A modeling of a PEM fuel cell is presented to determine both the bulk reactant concentrations and the catalyst surface concentrations at the catalyst layer-membrane layer interface. The results suggest that the reactant deficiencies experienced at high current densities are localized to the catalyst surface. However, the bulk concentration of reactant is not zero, and, in most cases, the bulk concentration of the reactant gases is significantly greater than zero. In actuality, it is the catalyst surface, which is being depleted of reactant, and, at the limiting current density, the surface concentrations of reactant gases are zero. This treatment develops explicitly link between the fuel cell overpotentials and the movement of reactants. DOI: http://dx.doi.org/10.3126/jie.v9i1.10662Journal of the Institute of Engineering Vol. 9, No. 1, pp. 1–17

A modified regression rate formula for the uppermost stage of CAMUI-type hybrid rocket motor is proposed in this study. Assuming a quasi-steady, one-dimensional, an energy balance against a control volume near the fuel surface is considered. Accordingly, the regression rate formula which can calculate the local regression rate by the quenching distance between the flame and the regression surface is derived. An experimental setup which simulates the combustion phenomenon involved in the uppermost stage of a CAMUI-type hybrid rocket motor was constructed and the burning tests with various flow velocities and impinging distances were performed. A PMMA slab of 20 mm height, 60 mm width, and 20 mm thickness was chosen as a sample specimen and pure oxygen and O2/N2mixture (50/50 vol.%) were employed as the oxidizers. The time-averaged regression rate along the fuel surface was measured by a laser displacement sensor. The quenching distance during the combustion event was also identified from the observation. The comparison between the purely experimental and calculated values showed good agreement, although a large systematic error was expected due to the difficulty in accurately identifying the quenching distance.

Construction workers are particularly susceptible to heat-related illnesses, for the weather is very hot and humid. The objective of this study is to investigate the interaction between the temperature and relative humidity to the physiological parameters such as heart rate (HR) and volume oxygen uptake (VO2 max) of the workers in the construction industry. The experiment was conducted in an environmental chamber which simulates the environment of the construction industry with three conditions combining air temperature and relative humidity (34 °C/74 %, 34 °C/92 %, 38 °C/83 %). The HR and the VO2 max of three subjects were monitored, and all the data were continuously recorded every 15 minutes. For each condition, the activity levels such as lifting the heavy sand (10 kg) were conducted for subjects. In the VO2 case, a significant correlation was observed between air temperature (p=0.043) and the relative humidity (p=0.000). Meanwhile, in HR case, a significant correlation was also observed between air temperature (p=0.004) and the relative humidity (p=0.028). The high-risk thermal environment (38 °C/83 %) and subject were identified. In conclusion, it can be empirically proved that environmental factor such as temperature and relative humidity have a significant impact on workers’ performance.

Abstract. Here, we present a three-dimensional fluid dynamic solver that simulates debris flows as a mixture of two fluids (a Coulomb viscoplastic model of the gravel mixed with a Herschel–Bulkley representation of the fine material suspension) in combination with an additional unmixed phase representing the air and the free surface. We link all rheological parameters to the material composition, i.e., to water content, clay content, and mineral composition, content of sand and gravel, and the gravel's friction angle; the user must specify only two free model parameters. The volume-of-fluid (VoF) approach is used to combine the mixed phase and the air phase into a single cell-averaged Navier–Stokes equation for incompressible flow, based on code adapted from standard solvers of the open-source CFD software OpenFOAM. This effectively single-phase mixture VoF method saves computational costs compared to the more sophisticated drag-force-based multiphase models. Thus, complex three-dimensional flow structures can be simulated while accounting for the pressure- and shear-rate-dependent rheology.

Abstract. Here we present a three-dimensional fluid dynamic solver that simulates debris flows as a mixture of two phases (gravel and fine material suspension) with a third unmixed phase representing the air and the free surface. We link all rheological parameters to the material composition, i.e., to water content, clay content and mineral composition, content of sand and gravel, and the gravel's friction angle; the user must specify only a single free model parameter. The Volume-Of-Fluid (VOF) approach is used to combine the three phases into a single cell-averaged Navier–Stokes equation for incompressible flow, based on code adapted from standard solvers of the Open-Source CFD software OpenFOAM. We present a stable implementation of a Coulomb-Viscoplastic model that represents the pressure-dependent flow behavior of the granular phase, and a Herschel–Bulkley representation of the interstitial fluid. The VOF method saves computational costs compared to drag-force based multiphase models. Thus depth-averaging is not necessary and complex three-dimensional flow structures can be simulated.

Abstract Dorota Lipowska. A Communicative Community of Agents. Lingua Posnaniensis, vol. L IV (1)/2012. The Poznań Society for the Advancement of the Arts and Sciences. PL ISSN 0079-4740, ISBN 978-83-7654-103-7, pp. 77-87. Computer modelling is becoming an increasingly important tool for researching the problem of origin and evolution of language. Afundamental technique is that of multi-agent modelling, which simulates a system of dynamically interacting individuals called agents, equipped with strictly defined properties and rules governing their behaviour or evolution. In such a population (a communicative community), as a result only of local interactions between agents, a process of self-organization occurs and some kind of global property emerges, such as linguistic coherence. Presented here are two models of the naming game type, in which agents exchange names of objects, gradually establishing a common vocabulary. In the evolutionary version there was observed a very strong link between biological and linguistic processes, being a clear manifestation of Baldwin’s effect - genetic assimilation of the ability to learn (a language, for example). In the multi-object version the development of homonymy and synonymy was studied, as well as the effect of noise on a developing language.

AbstractIn this study, the flow turbulence and variations of the supercritical free surface flow in a circular channel along a side weir are simulated as three dimensional using the RNG k-ε turbulence model and volume of fluid (VOF) scheme. Comparison between the numerical model and experimental measurements shows that the numerical model simulates the free surface flow with good accuracy. According to the numerical model results, the specific energy variations along the side weir for the supercritical flow regime are almost constant and the energy drop is not significant but by increasing the side weir length the energy difference between the side weir upstream and downstream increases. Next, using the nonlinear regression (NLR) and analysis of the simulation results, some relationships for calculating the discharge coefficient of side weir on circular channels in supercritical flow regime are provided.

Wave overtopping and the propagation of the waves on the crest and the landward slope of a coastal dike is investigated numerically. Wave overtopping conditions are simulated using the concept of the Wave Overtopping Simulator (WOS). Two numerical models of the WOS are constructed using the FLUENT 6.0.12 (FLUENT Inc. 2001) and the FLOW 3D 9.4 (FLOW 3D 2010) CFD codes. The former simulates the WOS without accounting for air entrainment while the latter accounts for air entrainment. The unsteady RANS equations, the RNG k-ε turbulence model and the VOF method are solved numerically, for "tracking" the free surface and the head of the "current" from the dike crest to the landward dike slope. The computed results from the two models are compared with each other and also against field measurements and proposed empirical relationships (Van der Meer et al. 2010).

This paper simulates regular waves propagating over a submerged parabolic obstacle in the presence of a uniform/shear current using a two-dimensional numerical model, named COBRAS (Cornell Breaking and Structure). The numerical model solves the Reynolds-Averaged Navier-Stokes (RANS) equations and the free surface deformation is tracked using the volume of fluid method (VOF). The capability of the numerical model to simulate regular waves with a uniform or shear current over a constant water depth is first validated with available analytical solutions and experimental data. Comparisons among the experimental data, analytical solutions, and present numerical results show good agreements. Then, regular waves propagating over a submerged parabolic obstacle with a following current are investigated. Detailed discussions including those on the velocity and vorticity fields and the relation between free surface and vorticity are given.

European hake (Merluccius merluccius) is an important commercial fisheries species that shows growth overfishing, with catches basically focused on juveniles. This study assesses the benefit of closing a coastal area (an essential habitat for European hake recruits) to fishing, in addition to other alternatives of spatial management, compared with traditional, non–spatial management scenarios on fishing grounds exploited by the bottom trawl fleets of Blanes and Palamós (Province of Girona, NE Spain). We use InVEST, a spatially explicit model of intermediate complexity that simulates the bioeconomic effects of management measures for decision making. The sensitivity analysis of the model results shows the high influence of some parameters, particularly the parameterization of the recruitment submodel and European hake’s fecundity coefficients. The results are also examined in the light of uncertainty on migration parameters: in the two cases analysed (considering migration patterns or not), the results of the indicators (catch and revenues, abundance, recruitment and spawning stock biomass) were qualitatively similar and all show that the application of a restricted fishing area in one particular fishing ground (Vol de Terra) is the best management alternative. Its bioeconomic effects are comparable to a reduction of fishing effort of up to 20%. With high levels of ontogenetic migration, fishing on a second fishing ground (Cul de Rec – El Pas) should be restricted to enhance the biomass of the European hake population.

Pipelines located on the decks of FPSO systems are exposed to damage due to sea wave induced random loading. In this context, a methodology for estimating the fatigue life of fluid-conveying pipelines is presented. The pipeline is subjected to a random support motion that simulates the effect of the FPSO heaving. The equation of motion of the pipeline is derived by assuming small amplitude displacements, modeling the empty pipeline as a Bernoulli-Euler beam, and adopting the so-called “plug-flow” approximation for the fluid (Fluid-Structure Interactions Slender Structures and Axial Flow, Academic Press, San Diego, Vol. 1). Random vibration analysis is carried out by the Galerkin method selecting as basis functions the natural modes of a beam with the same boundary conditions as the pipeline. The discretized equations of motion are used in conjunction with linear random vibration theory to compute the stress spectrum for a generic section of the pipeline. For this purpose, the power spectrum of the acceleration at the deck level is determined by using the Response Amplitude Operator of the FPSO hull. Finally, the computed stress spectrum is used to estimate the pipeline fatigue life employing an appropriate S-N fatigue curve of the material. An illustrative example concerning a pipeline simply supported at both ends is included in the paper.

Abstract The global monsoon climate variability during the second half of the twentieth century simulated by 21 coupled global climate models (CGCMs) that participated in the World Climate Research Programme’s Coupled Model Intercomparison Project phase 3 (CMIP3) is evaluated. Emphasis was placed on climatology, multidecadal trend, and the response of the global monsoon precipitation to volcanic aerosols. The impact of the atmospheric model’s horizontal resolution on the group ensemble mean (GEM; obtained from the three resolution groups) simulations of global monsoon climate is also examined. The CMIP3 CGCMs’ multimodel ensemble simulates a reasonably realistic climatology of the global monsoon precipitation and circulation. The GEMs are also able to capture the gross features of the global monsoon precipitation and westerly domains. However, the spreading among the rainfall GEMs is large, particularly at the windward side of narrow mountains (e.g., the western coast of India, the Philippines, Mexico, and the steep slope of the Tibetan Plateau). Main common biases in modeling rainfall climatology include a northeastward shift of the intertropical convergence zone (ITCZ) in the tropical North Pacific and a southward migration of the North Atlantic ITCZ during boreal winter. The trend in the Northern Hemisphere land monsoon index (NHMI) detected in the CMIP3 models is generally consistent with the observations, albeit with much weaker magnitude. The significant decreasing NHMI trend during 1951–85 and 1951–99 occurs mainly in the models with volcanic aerosols (VOL models). This volcanic signal is detectable by comparison of the forced and free runs. It is estimated that from about one-quarter to one-third of the drying trend in the Northern Hemisphere land monsoon precipitation over the latter half of the twentieth century was likely due to the effects of the external volcanic forcings. On the other hand, the significant increasing trend in the global ocean monsoon index (GOMI) during 1980–99 appears chiefly in those models that are free of volcanic aerosols (No-VOL models). The exclusion of the volcanic aerosols is significant in simulating the positive GOMI trend against the internal variability of each model. These results suggest the climatic importance of the volcanic forcings in the global monsoon precipitation variability.

It has been recently shown that the energy-containing motions (i.e. coherent structures) in turbulent channel flow exist in the form of Townsend’s attached eddies by a numerical experiment which simulates the energy-containing motions only at a prescribed spanwise length scale using their self-sustaining nature (Hwang, J. Fluid Mech., vol. 767, 2015, pp. 254–289). In the present study, a detailed investigation of the self-sustaining process of the energy-containing motions at each spanwise length scale (i.e. the attached eddies) in the logarithmic and outer regions is carried out with an emphasis on its relevance to ‘bursting’, which refers to an energetic temporal oscillation of the motions (Flores & Jiménez, Phys. Fluids, vol. 22, 2010, 071704). It is shown that the attached eddies in the logarithmic and outer regions, composed of streaks and quasi-streamwise vortical structures, bear the self-sustaining process remarkably similar to that in the near-wall region: i.e. the streaks are significantly amplified by the quasi-streamwise vortices via the lift-up effect; the amplified streaks subsequently undergo a ‘rapid streamwise meandering motion’, reminiscent of streak instability or transient growth, which eventually results in breakdown of the streaks and regeneration of new quasi-streamwise vortices. For the attached eddies at a given spanwise length scale ${\it\lambda}_{z}$ between ${\it\lambda}_{z}^{+}\simeq 100$ and ${\it\lambda}_{z}\simeq 1.5h$, the single turnover time period of the self-sustaining process is found to be $Tu_{{\it\tau}}/{\it\lambda}_{z}\simeq 2$ ($u_{{\it\tau}}$ is the friction velocity), which corresponds well to the time scale of the bursting. Two additional numerical experiments, designed to artificially suppress the lift-up effect and the streak meandering motions, respectively, reveal that these processes are essential ingredients of the self-sustaining process of the attached eddies in the logarithmic and outer regions, consistent with several previous theoretical studies. It is also shown that the artificial suppression of the lift-up effect of the attached eddies in the logarithmic and outer regions leads to substantial amounts of turbulent skin-friction reduction.

Abstract. We present a computationally efficient approach to account for the non-linear chemistry occurring during the dispersion of ship exhaust plumes in a global 3-D model of atmospheric chemistry (GEOS-Chem). We use a plume-in-grid formulation where ship emissions age chemically for 5 h before being released in the global model grid. Besides reducing the original ship NOx emissions in GEOS-Chem, our approach also releases the secondary compounds ozone and HNO3, produced in the 5 h after the original emissions, into the model. We applied our improved method and also the widely used "instant dilution" approach to a 1-yr GEOS-Chem simulation of global tropospheric ozone-NOx-VOC-aerosol chemistry. We also ran simulations with the standard model, and a model without any ship emissions at all. Our improved GEOS-Chem model simulates up to 0.1 ppbv (or 90 %) more NOx over the North Atlantic in July than GEOS-Chem versions without any ship NOx emissions at all. "Instant dilution" overestimates NOx concentrations by 50 % (0.1 ppbv) and ozone by 10–25 % (3–5 ppbv) over this region. These conclusions are supported by comparing simulated and observed NOx and ozone concentrations in the lower troposphere over the Pacific Ocean. The comparisons show that the improved GEOS-Chem model simulates NOx concentrations in between the instant diluting model and the model with no ship emissions, and results in lower O3 concentrations than the instant diluting model. The relative differences in simulated NOx and ozone between our improved approach and instant dilution are smallest over strongly polluted seas (e.g. North Sea), suggesting that accounting for in-plume chemistry is most relevant for pristine marine areas.

Abstract. We present a computationally efficient approach to account for the non-linear chemistry occurring during the dispersion of ship exhaust plumes in a global 3-D model of atmospheric chemistry (GEOS-Chem). We use a plume-in-grid formulation where ship emissions age chemically for 5 h before being released in the global model grid. Besides reducing the original ship NOx emissions in GEOS-Chem, our approach also releases the secondary compounds ozone and HNO3, produced during the 5 h after the original emissions, into the model. We applied our improved method and also the widely used "instant dilution" approach to a 1-yr GEOS-Chem simulation of global tropospheric ozone-NOx-VOC-aerosol chemistry. We also ran simulations with the standard model (emitting 10 molecules O3 and 1 molecule HNO3 per ship NOx molecule), and a model without any ship emissions at all. The model without any ship emissions simulates up to 0.1 ppbv (or 50%) lower NOx concentrations over the North Atlantic in July than our improved GEOS-Chem model. "Instant dilution" overestimates NOx concentrations by 0.1 ppbv (50%) and ozone by 3–5 ppbv (10–25%), compared to our improved model over this region. These conclusions are supported by comparing simulated and observed NOx and ozone concentrations in the lower troposphere over the Pacific Ocean. The comparisons show that the improved GEOS-Chem model simulates NOx concentrations in between the instant dilution model and the model without ship emissions, which results in lower O3 concentrations than the instant dilution model. The relative differences in simulated NOx and ozone between our improved approach and instant dilution are smallest over strongly polluted seas (e.g. North Sea), suggesting that accounting for in-plume chemistry is most relevant for pristine marine areas.

Abstract. The particulate matter source apportionment technology (PSAT) is used together with PMCAMx, a regional chemical transport model, to estimate how local emissions and pollutant transport affect primary and secondary particulate matter mass concentration levels in Paris. During the summer and the winter periods examined, only 13% of the PM2.5 is predicted to be due to local Paris emissions, with 36% coming from mid-range (50–500 km from the center of the Paris) sources and 51% from long range transport (more than 500 km from Paris). The local emissions contribution to simulated elemental carbon (EC) is significant, with almost 60% of the EC originating from local sources during both summer and winter. Approximately 50% of the simulated fresh primary organic aerosol (POA) originated from local sources and another 45% from areas 100–500 km from the receptor region during summer. Regional sources dominated the secondary PM components. During summer more than 70% of the simulated sulfate originated from SO2 emitted more than 500 km away from the center of the Paris. Also more than 45% of secondary organic aerosol (SOA) was due to the oxidation of VOC precursors that were emitted 100–500 km from the center of the Paris. The model simulates more contribution from long range secondary PM sources during winter because the timescale for its production is longer due to the slower photochemical activity. PSAT results for contributions of local and regional sources were compared with observation-based estimates from field campaigns that took place during the MEGAPOLI project. PSAT simulations are in general consistent (within 20%) with these estimates for OA and sulfate. The only exception is that PSAT simulates higher local EC contribution during the summer compared to that estimated from observations.

Abstract Abstract 1138 Poster Board I-160 Background The MHC class I-related chain A (MICA) molecules is of particular in non T-cell receptor (TCR)-mediated immune function. MICA engages NKG2D, a C-type lectin expressed on effector cells including NK, and T cells. Such engagement triggers NK cells and co-simulates T lymphocytes to mount adequate immune response. Further, a soluble isoform of MICA (sMICA) has been implicated in the pathogenesis of a variety of cancers, auto-immune and other organ transplant-related disorders through NKG2D receptor down regulation. Functionally relevant polymorphism of the MICA gene may also contribute to inter-patients variability in allo-immune responses as observed in various clinical settings including organ-transplantation. A methionine (met) to valine (val) change at position 129 of the alpha 2-heavy chain domain categorized the MICA alleles into strong (MICA-129 met) and weak (MICA-129 val) binders of NKG2D receptor. Given the demonstrated importance of MICA in immune pathways, in this study, we explored the MICA-related parameters namely MICA-129 gene polymorphism, pre- and post-transplant serum levels of soluble MICA (sMICA) and anti-MICA antibodies (MICA Abs) in a HLA-matched sibling HSCT setting. Results We evaluated whether MICA-129 gene polymorphism, pre- and post-HSCT sMICA and MICA Abs could influence the incidence of chronic graft-versus-host disease (c.GvHD) and relapse of their disease in 211 HLA-identical sibling pairs. In multivariate analysis on chronic GvHD risk, 3 factors reached significance: recipient MICA-129 val/val genotype (HR = 1.52; 95% confidence interval [95%CI] = 1.02-2.24; P =.04), older recipient age (3 15 years) (HR = 3.36; 95%CI = 1.65-6.84; P =.001) and source of stem cells (PBSC vs BM) (HR = 1.67; 95%CI = 1.10-2.53; P =.017). Since acute GvHD (aGvHD) is a major risk factor of subsequent c.GvHD, we then introduced aGvHD as a time-dependant co-variate in the multivariate analysis model. This analysis confirmed that the risk conferred by the MICA-129 val/val genotype is independent from aGvHD. Elevated post-HSCT sMICA serum levels were also independently associated with c.GvHD (p =.0001) regardless of history of acute GvHD. On the contrary, the presence of pre-transplant MICA Abs confers protection against c.GvHD (p =.04). There was an inverse relationship between MICA Abs and sMICA suggesting an antibody-based neutralization of deleterious effects of sMICA. Similarly, these genetic and phenotype characteristics of MICA influence the incidence of relapse. Conclusion Altogether, these data suggest that the studied MICA genotype and phenotype specificities could be used as relevant biomarkers for c.GvHD monitoring. Disclosures No relevant conflicts of interest to declare.

AbstractWhen flow surface is higher than of a side weir crest, the overflow spilt over the crest and divert into a side channel. These structures are extensively used in urban sewage disposal networks, water supply systems, and drainage and flood diversion networks. This study simulates stream free surface, discharge over a sharp-crest side weir, and discharge coefficient of a side weir in a circular channel using FLOW-3D software. Numerical model results were compared with the experimental ones and the comparison proved an acceptable consistency between the numerical and experimental results. RNG k-ε turbulence model was used for simulating flow turbulence. The volume of fluid (VOF) method was used in this CFD analysis for predicting changes of flow free surface. Then, the numerical simulation results were examined for discharge coefficient of the side weir and flow free surface for different discharge passing through the main channel. The changes of dividing stream surface from main channel bed toward stream free surface were examined. The concluding section assessed the effect of shape of a circular channel on the pattern and intensity of a secondary flow in the main channel and the impacts of the discharge passing through the circular channel on height of stagnation point and shear stress pattern in the main channel bed.

This paper continues a series of works developing a model for a high-speed boiling flow capable of describing different fluxes with no change in the model coefficients. Refining the interfacial area transport equation in partial derivatives, we test the ability of the model to describe phenomena that cannot be simulated by models that average the interfacial interaction. In the previous version, the possibility for bubble fragmentation was considered, which permitted us to reproduce an explosive boiling in rarefaction shocks moving at a speed of ${\sim}10~\text{m}~\text{s}^{-1}$ fixed in experiments on hot water decompression. The shocks were shown to be caused by a chain bubble fragmentation leading to a sharp increase in the interphase area (Ivashnyov et al., J. Fluid Mech., vol. 413, 2000, pp. 149–180). With no change in the free parameters (the initial number of boiling centres in the flow bulk and the critical Weber number) chosen for a tube decompression, the model gave close predictions for critical flows in long nozzles, $L/D\sim 100$. The formation of a boiling shock in the nozzle was shown to be the reason for the onset of autovibrated regimes (Ivashnyov & Ivashneva, J. Fluid Mech., vol. 710, 2012, pp. 72–101). However, the previous model does not simulate the phenomenon of a vapour explosion at a primary stage of a hot water decompression, when the first rarefaction wave is followed by an extended, 1 m width, several MPa amplitude compression wave in which the pressure reaches a plateau below a saturation value. The model proposed assumes initial boiling centre origination at the channel walls. Due to overflowing, the wall bubbles break up, with their fragments passing into the flow. On growing up, the flow bubbles can break up in their turn. It is shown that an extended compression wave is caused by the fragmentation of wall bubbles, which leads to the increase in the interphase area, boiling intensification and the pressure rise. The pressure reaches a plateau before a saturation state is reached due to flow momentum loss accelerating the fragments of wall bubbles. The phenomenon of pressure ‘oscillation’ fixed in some experimental oscillograms when the pressure in the compression wave increases up to a saturation pressure and then drops to the plateau value has been explained as well. The ‘illposedness’ defect of the generally accepted model for two-phase two-velocity flow with a compressible carrying phase, which lies in its complex characteristics, has been rectified. The calculations of a stationary countercurrent liquid-particle flow in a diffuser with the improved hyperbolic model predicts a critical regime with a maximal liquid mass flux, while the old non-hyperbolic model simulates the supercritical regimes with ‘numerical instabilities’. Calculations of a transient upward flow of particles have shown the formation of a superslow ‘creeping’ shock wave of particles compacting.

Routing is the modeling process to determine the outflow at an outlet from given inflow at upstream of the channel. A hydrological simulation model use mathematical equations that establish relationships between inputs and outputs of water system and simulates the catchment response to the rainfall input. Several hydrological models have been developed to assist in understanding of hydrologic system and water resources management. A model, once calibrated and verified on catchments, provides a multi-purpose tool for further analysis. Semi-Distributed models in hydrology are usually physically based in that they are defined in terms of theoretically acceptable continuum equations. They do, however, involve some degree of lumping since analytical solutions to the equations cannot be found, and so approximate numerical solutions, based on a finite difference or finite element discretization of the space and time dimensions, are implemented. Many rivers in Nepal are either ungauged or poorly gauged due to extreme complex terrains, monsoon climate and lack of technical and financial supports. In this context the role of hydrological models are extremely useful. In practical applications, hydrological routing methods are relatively simple to implement reasonably accurate. In this study, Gandaki river basin was taken for the study area. Kinematic wave method was used for overland routing and Muskingum cunge method was applied for channel routing to describe the discharge on Narayani river and peak flow attenuation and dispersion observed in the direct runoff hydrograph. Channel cross section parameters are extracted using HEC- GeoRAS extension tool of GIS. From this study result, Annual runoff, Peak flow and time of peak at the outlet are similar to the observed flow in calibration and verification period using trapezoidal channel. Hence Hydrological modeling is a powerful technique in the planning and development of integrated approach for management of water resources. DOI: http://dx.doi.org/10.3126/jie.v10i1.10877Journal of the Institute of Engineering, Vol. 10, No. 1, 2014 pp. 45-58

Abstract. This work documents and evaluates the tropospheric gas-phase chemical mechanism MOGUNTIA in the three-dimensional chemistry transport model TM5-MP. Compared to the modified CB05 (mCB05) chemical mechanism previously used in the model, MOGUNTIA includes a detailed representation of the light hydrocarbons (C1–C4) and isoprene, along with a simplified chemistry representation of terpenes and aromatics. Another feature implemented in TM5-MP for this work is the use of the Rosenbrock solver in the chemistry code, which can replace the classical Euler backward integration method of the model. Global budgets of ozone (O3), carbon monoxide (CO), hydroxyl radicals (OH), nitrogen oxides (NOx), and volatile organic compounds (VOCs) are analyzed, and their mixing ratios are compared with a series of surface, aircraft, and satellite observations for the year 2006. Both mechanisms appear to be able to satisfactorily represent observed mixing ratios of important trace gases, with the MOGUNTIA chemistry configuration yielding lower biases than mCB05 compared to measurements in most of the cases. However, the two chemical mechanisms fail to reproduce the observed mixing ratios of light VOCs, indicating insufficient primary emission source strengths, oxidation that is too fast, and/or a low bias in the secondary contribution to C2–C3 organics via VOC atmospheric oxidation. Relative computational memory and time requirements of the different model configurations are also compared and discussed. Overall, the MOGUNTIA scheme simulates a large suite of oxygenated VOCs that are observed in the atmosphere at significant levels. This significantly expands the possible applications of TM5-MP.

Abstract. Tropospheric ozone is an air pollutant that substantially harms vegetation and is also strongly dependent on various vegetation-mediated processes. The interdependence between ozone and vegetation may constitute feedback mechanisms that can alter ozone concentration itself but have not been considered in most studies to date. In this study we examine the importance of dynamic coupling between surface ozone and leaf area index (LAI) in shaping ozone air quality and vegetation. We first implement an empirical scheme for ozone damage on vegetation in the Community Land Model (CLM) and simulate the steady-state responses of LAI to long-term exposure to a range of prescribed ozone levels (from 0 to 100 ppb). We find that most plant functional types suffer a substantial decline in LAI as ozone level increases. Based on the CLM-simulated results, we develop and implement in the GEOS-Chem chemical transport model a parameterization that computes fractional changes in monthly LAI as a function of local mean ozone levels. By forcing LAI to respond to ozone concentrations on a monthly timescale, the model simulates ozone–LAI coupling dynamically via biogeochemical processes including biogenic volatile organic compound (VOC) emissions and dry deposition, without the complication from meteorological changes. We find that ozone-induced damage on LAI can lead to changes in ozone concentrations by −1.8 to +3 ppb in boreal summer, with a corresponding ozone feedback factor of −0.1 to +0.6 that represents an overall self-amplifying effect from ozone–LAI coupling. Substantially higher simulated ozone due to strong positive feedbacks is found in most tropical forests, mainly due to the ozone-induced reductions in LAI and dry deposition velocity, whereas reduced isoprene emission plays a lesser role in these low-NOx environments. In high-NOx regions such as the eastern US, Europe, and China, however, the feedback effect is much weaker and even negative in some regions, reflecting the compensating effects of reduced dry deposition and reduced isoprene emission (which reduces ozone in high-NOx environments). In remote, low-LAI regions, including most of the Southern Hemisphere, the ozone feedback is generally slightly negative due to the reduced transport of NOx–VOC reaction products that serve as NOx reservoirs. This study represents the first step to accounting for dynamic ozone–vegetation coupling in a chemical transport model with ramifications for a more realistic joint assessment of ozone air quality and ecosystem health.

Abstract. We present an evaluation of sources, sinks and turbulent transport of nitrogen oxides, ozone and volatile organic compounds (VOC) in the boundary layer over French Guyana and Suriname during the October 2005 GABRIEL campaign by simulating observations with a single-column chemistry and climate model (SCM) along a zonal transect. Simulated concentrations of O3 and NO as well as NO2 photolysis rates over the forest agree well with observations when a small soil-biogenic NO emission flux was applied. This suggests that the photochemical conditions observed during GABRIEL reflect a pristine tropical low-NOx regime. The SCM uses a compensation point approach to simulate nocturnal deposition and daytime emissions of acetone and methanol and produces daytime boundary layer mixing ratios in reasonable agreement with observations. The area average isoprene emission flux, inferred from the observed isoprene mixing ratios and boundary layer height, is about half the flux simulated with commonly applied emission algorithms. The SCM nevertheless simulates too high isoprene mixing ratios, whereas hydroxyl concentrations are strongly underestimated compared to observations, which can at least partly explain the discrepancy. Furthermore, the model substantially overestimates the isoprene oxidation products methlyl vinyl ketone (MVK) and methacrolein (MACR) partly due to a simulated nocturnal increase due to isoprene oxidation. This increase is most prominent in the residual layer whereas in the nocturnal inversion layer we simulate a decrease in MVK and MACR mixing ratios, assuming efficient removal of MVK and MACR. Entrainment of residual layer air masses, which are enhanced in MVK and MACR and other isoprene oxidation products, into the growing boundary layer poses an additional sink for OH which is thus not available for isoprene oxidation. Based on these findings, we suggest pursuing measurements of the tropical residual layer chemistry with a focus on the nocturnal depletion of isoprene and its oxidation products.

Abstract. We present an evaluation of sources, sinks and turbulent transport of nitrogen oxides, ozone and volatile organic compounds (VOC) in the boundary layer over French Guyana and Suriname during the October 2005 GABRIEL campaign by simulating observations with a single-column chemistry and climate model (SCM) along a zonal transect. Simulated concentrations of O3 and NO as well as NO2 photolysis rates over the forest agree well with observations when a small soil-biogenic NO emission flux was applied. This suggests that the photochemical conditions observed during GABRIEL reflect a pristine tropical low-NOx regime. The SCM uses a compensation point approach to simulate nocturnal deposition and daytime emissions of acetone and methanol and produces daytime boundary layer mixing ratios in reasonable agreement with observations. The area average isoprene emission flux, inferred from the observed isoprene mixing ratios and boundary layer height, is about half the flux simulated with commonly applied emission algorithms. The SCM nevertheless simulates too high isoprene mixing ratios, whereas hydroxyl concentrations are strongly underestimated compared to observations, which can at least partly explain the discrepancy. Furthermore, the model substantially overestimates the isoprene oxidation products methlyl vinyl ketone (MVK) and methacrolein (MACR) partly due to a simulated nocturnal increase due to isoprene oxidation. This increase is most prominent in the residual layer whereas in the nocturnal inversion layer we simulate a decrease in MVK and MACR mixing ratios, assuming efficient removal of MVK and MACR. Entrainment of residual layer air masses, which are enhanced in MVK and MACR and other isoprene oxidation products, into the growing boundary layer poses an additional sink for OH which is thus not available for isoprene oxidation. Based on these findings, we suggest pursuing measurements of the tropical residual layer chemistry with a focus on the nocturnal depletion of isoprene and its oxidation products.

Abstract. To improve the operational air quality forecasting over China, a new aerosol or gas-phase pollutants assimilation capability is developed within the WRFDA system using the three-dimensional variational (3DVAR) algorithm. In this first application, the interface for the MOSAIC (Model for Simulating Aerosol Interactions and Chemistry) aerosol scheme is built with the potential for flexible extension. Based on the new WRFDA-Chem system, five experiments assimilating different surface observations, including PM2.5, PM10, SO2, NO2, O3, and CO, are conducted for January 2017 along with a control experiment without data assimilation (DA). Results show that the WRFDA-Chem system evidently improves the air quality forecasting. From the analysis aspect, the assimilation of surface observations reduces the bias and RMSE in the initial condition (IC) remarkably; from the forecast aspect, better forecast performances are acquired up to 24 h, in which the experiment assimilating the six pollutants simultaneously displays the best forecast skill overall. With respect to the impact of the DA cycling frequency, the responses toward IC updating are found to be different among the pollutants. For PM2.5, PM10, SO2, and CO, the forecast skills increase with the DA frequency. For O3, although improvements are acquired at the 6 h cycling frequency, the advantage of more frequent DA could be consumed by the disadvantages of the unbalanced photochemistry (due to inaccurate precursor NOx ∕ VOC (volatile organic compound) ratios) or the changed titration process (due to changed NO2 concentrations but not NO) from assimilating the existing observations (only O3 and NO2, but no VOC and NO). As yet the finding is based on the 00:00 UTC forecast for this winter season only, and O3 has strong diurnal and seasonal variations. More experiments should be conducted to draw further conclusions. In addition, considering one aspect (IC) in the model is corrected by DA, the deficiencies of other aspects (e.g., chemical reactions) could be more evident. This study explores the model deficiencies by investigating the effects of assimilating gaseous precursors on the forecast of related aerosols. Results show that the parameterization (uptake coefficients) in the newly added sulfate–nitrate–ammonium (SNA)-relevant heterogeneous reactions in the model is not fully appropriate although it best simulates observed SNA aerosols without DA; since the uptake coefficients were originally tuned under the inaccurate gaseous precursor scenarios without DA, the biases from the two aspects (SNA reactions and IC DA) were just compensated. In future chemistry development, parameterizations (such as uptake coefficients) for different gaseous precursor scenarios should be adjusted and verified with the help of the DA technique. According to these results, DA ameliorates certain aspects by using observations as constraints and thus provides an opportunity to identify and diagnose the model deficiencies; it is useful especially when the uncertainties of various aspects are mixed up and the reaction paths are not clearly revealed. In the future, besides being used to improve the forecast through updating IC, DA could be treated as another approach to explore necessary developments in the model.

The paper deals with studying a dynamic stability of the wing model in the ram airflow. As known, at a certain flow rate that is called critical, there is a phenomenon of self-excited non-damping flexural-torsional self-vibrations, named flutter. A two-mode elastic system wing model is under consideration, as is common in the literature in the field concerned. The paper continues and develops investigations of well-known scientists in this field, such as V.L. Biderman, S.P. Strelkov, Ya.G. Panovko, I. I. Gubanova, E.P. Grossman, J.Ts. Funen, etc. A great deal of papers dedicated to this problem and published by abovementioned and other scientists, give only the problem formulation and the derivation of equations, often in a fairly simplified form, do not offer solutions of these equations for specific numerical parameters of the wing model, and do not study how these parameters affect the flutter onset velocity.The paper details the derivation of linear differential equations of small vibrations of the wing model in the flow, determines the natural frequencies and shapes of flexural-torsional vibrations, checks their orthogonality, studies vibrations under the influence of aerodynamic force and moment, determines the critical flow velocity for a number of system parameters, and draws a conclusion about the influence of these parameters on the critical velocity. In particular, it studies how such a parameter as the distance between the center of gravity and the center of stiffness affects the critical velocity, as well as how the stiffness of the model's spring suspension, which simulates the stiffness characteristics of the wing impacts on bending and torsion. The calculation results allow us to draw conclusion concerning the methods of dealing with this phenomenon. One of the promising options may be, in addition to varying the geometric and rigid parameters of the system, the introduction of additional mass to be an analogue of the vibration damper. The paper may be of interest both for engineering students who learn the theory of mechanical vibrations, and for engineering-specialists in aero-elasticity and dynamic stability of elements in mechanical systems.

Information about character of burden materials behavior inside a blast furnace at its different horizons enables to increase control efficiency of BF heat running. The elaborated complex of methodologies for carbon materials and iron ore raw materials properties study enables to simulate their behavior at the horizon of iron ore materials reducing, in the viscoplastic zone, at the horizon of iron ore raw materials smelting and its interaction with coke filling. A vertical electric resistance shaft furnace with a tube carbon heater was used as a base equipment for simulation of burden behavior in the reduction zone and smelting zone, as well as for simulation of iron ore burden melt outflow through coke filling. Burden materials preparation to the experiment concluded in crushing of iron ore component followed by 3–5 mm fraction extraction and a mixing it with 3–5 mm fraction of brown coal semi-coke in relation 2:1 for further heating-reduction treatment. The heating-reduction treatment of the mixture charged in the electric furnace simulates the reducing zone and is carried out by a slow heating of the iron ore component and reducing agent mixture from 20 up to 980–1020 ºС. The methodology of determination of lump carbon materials combustibility in the highly heated air blast flow was developed for the complex of equipment based on the shaft electric resistance furnace and aimed at testing of burning process of carbon samples of technological fuels. The combustibility was determined under conditions of burnt sample heating in the temperature range from 500 up to 1500 °C with an accuracy of ±10 °С. The temperature of air blast flow (21 % vol. of oxygen at natural moisture) was set in the range from 120 up to 1200 °С and was kept with an accuracy of ±12 °С. The burnt sample mass, volume of air blast and its velocity was correlated to obtaining of complex non-dimensional Re factor (Reinolds number) more than 100, that guaranteed a reliable process running in the combustion area with no risk of transferring to gasification process. Based on GOST 26517–85 (“Iron ores, sinter and pellets”) a methodology was elaborated for determining of parameters of iron ore materials status in the viscoplastic zone. The methodology comprises heating of preliminary reduced sample of a tested iron ore material in an inert gas and determination of softening temperature and smelting end by a hard rod sinking into the material layer under external pressure action. The temperature at which the layer shrinkage reaches level of 2% during heating, was taken as the softening temperature of the iron ore material. The sinking of the rod into the material by 80% was taken as the temperature of the beginning of the material melting. The interval softening-melting was determined as the difference between melting temperature and softening temperature (at sample shrinkage by 2 %).

Abstract. We employ the WRF-Chem model to study summertime air pollution, the intense photochemical activity and their impact on air quality over the eastern Mediterranean. We utilize three nested domains with horizontal resolutions of 80, 16 and 4 km, with the finest grid focusing on the island of Cyprus, where the CYPHEX campaign took place in July 2014. Anthropogenic emissions are based on the EDGAR HTAP global emission inventory, while dust and biogenic emissions are calculated online. Three simulations utilizing the CBMZ-MOSAIC, MOZART-MOSAIC, and RADM2-MADE/SORGAM gas-phase and aerosol mechanisms are performed. The results are compared with measurements from a dense observational network of 14 ground stations in Cyprus. The model simulates T2 m, Psurf, and WD10 m accurately, with minor differences in WS10 m between model and observations at coastal and mountainous stations attributed to limitations in the representation of the complex topography in the model. It is shown that the south-eastern part of Cyprus is mostly affected by emissions from within the island, under the dominant (60 %) westerly flow during summertime. Clean maritime air from the Mediterranean can reduce concentrations of local air pollutants over the region during westerlies. Ozone concentrations are overestimated by all three mechanisms (9 % ≤ NMB ≤ 23 %) with the smaller mean bias (4.25 ppbV) obtained by the RADM2-MADE/SORGAM mechanism. Differences in ozone concentrations can be attributed to the VOC treatment by the three mechanisms. The diurnal variability of pollution and ozone precursors is not captured (hourly correlation coefficients for O3 ≤ 0.29). This might be attributed to the underestimation of NOx concentrations by local emissions by up to 50 %. For the fine particulate matter (PM2.5), the lowest mean bias (9 µg m−3) is obtained with the RADM2-MADE/SORGAM mechanism, with overestimates in sulfate and ammonium aerosols. Overestimation of sulfate aerosols by this mechanism may be linked to the SO2 oxidation in clouds. The MOSAIC aerosol mechanism overestimates PM2.5 concentrations by up to 22 µg m−3 due to a more pronounced dust component compared to the other two mechanisms, mostly influenced by the dust inflow from the global model. We conclude that all three mechanisms are very sensitive to boundary conditions from the global model for both gas-phase and aerosol pollutants, in particular dust and ozone.

Abstract. The global oxidation capacity, defined as the tropospheric mean concentration of the hydroxyl radical (OH), controls the lifetime of reactive trace gases in the atmosphere such as methane and carbon monoxide (CO). Models tend to underestimate the methane lifetime and CO concentrations throughout the troposphere, which is consistent with excessive OH. Approximately half of the oxidation of methane and non-methane volatile organic compounds (VOCs) is thought to occur over the oceans where oxidant chemistry has received little validation due to a lack of observational constraints. We use observations from the first two deployments of the NASA ATom aircraft campaign during July–August 2016 and January–February 2017 to evaluate the oxidation capacity over the remote oceans and its representation by the GEOS-Chem chemical transport model. The model successfully simulates the magnitude and vertical profile of remote OH within the measurement uncertainties. Comparisons against the drivers of OH production (water vapor, ozone, and NOy concentrations, ozone photolysis frequencies) also show minimal bias, with the exception of wintertime NOy. The severe model overestimate of NOy during this period may indicate insufficient wet scavenging and/or missing loss on sea-salt aerosols. Large uncertainties in these processes require further study to improve simulated NOy partitioning and removal in the troposphere, but preliminary tests suggest that their overall impact could marginally reduce the model bias in tropospheric OH. During the ATom-1 deployment, OH reactivity (OHR) below 3 km is significantly enhanced, and this is not captured by the sum of its measured components (cOHRobs) or by the model (cOHRmod). This enhancement could suggest missing reactive VOCs but cannot be explained by a comprehensive simulation of both biotic and abiotic ocean sources of VOCs. Additional sources of VOC reactivity in this region are difficult to reconcile with the full suite of ATom measurement constraints. The model generally reproduces the magnitude and seasonality of cOHRobs but underestimates the contribution of oxygenated VOCs, mainly acetaldehyde, which is severely underestimated throughout the troposphere despite its calculated lifetime of less than a day. Missing model acetaldehyde in previous studies was attributed to measurement uncertainties that have been largely resolved. Observations of peroxyacetic acid (PAA) provide new support for remote levels of acetaldehyde. The underestimate in both model acetaldehyde and PAA is present throughout the year in both hemispheres and peaks during Northern Hemisphere summer. The addition of ocean sources of VOCs in the model increases cOHRmod by 3 % to 9 % and improves model–measurement agreement for acetaldehyde, particularly in winter, but cannot resolve the model summertime bias. Doing so would require 100 Tg yr−1 of a long-lived unknown precursor throughout the year with significant additional emissions in the Northern Hemisphere summer. Improving the model bias for remote acetaldehyde and PAA is unlikely to fully resolve previously reported model global biases in OH and methane lifetime, suggesting that future work should examine the sources and sinks of OH over land.

Abstract. Semi-volatile and intermediate-volatility organic compounds (SVOCs and IVOCs) from anthropogenic sources are likely to be important precursors of secondary organic aerosol (SOA) in urban airsheds, yet their treatment in most models is based on limited and obsolete data or completely missing. Additionally, gas-phase oxidation of organic precursors to form SOA is influenced by the presence of nitric oxide (NO), but this influence is poorly constrained in chemical transport models. In this work, we updated the organic aerosol model in the UCD/CIT (University of California at Davis/California Institute of Technology) chemical transport model to include (i) a semi-volatile and reactive treatment of primary organic aerosol (POA), (ii) emissions and SOA formation from IVOCs, (iii) the NOx influence on SOA formation, and (iv) SOA parameterizations for SVOCs and IVOCs that are corrected for vapor wall loss artifacts during chamber experiments. All updates were implemented in the statistical oxidation model (SOM) that simulates the oxidation chemistry, thermodynamics, and gas–particle partitioning of organic aerosol (OA). Model treatment of POA, SVOCs, and IVOCs was based on an interpretation of a comprehensive set of source measurements available up to the year 2016 and resolved broadly by source type. The NOx influence on SOA formation was calculated offline based on measured and modeled VOC:NOx ratios. Finally, the SOA formation from all organic precursors (including SVOCs and IVOCs) was modeled based on recently derived parameterizations that accounted for vapor wall loss artifacts in chamber experiments. The updated model was used to simulate a 2-week summer episode over southern California at a model resolution of 8 km. When combustion-related POA was treated as semi-volatile, modeled POA mass concentrations were reduced by 15 %–40 % in the urban areas in southern California but were still too high when compared against “hydrocarbon-like organic aerosol” factor measurements made at Riverside, CA, during the Study of Organic Aerosols at Riverside (SOAR-1) campaign of 2005. Treating all POA (except that from marine sources) to be semi-volatile, similar to diesel exhaust POA, resulted in a larger reduction in POA mass concentrations and allowed for a better model–measurement comparison at Riverside, but this scenario is unlikely to be realistic since this assumes that POA from sources such as road and construction dust are semi-volatile too. Model predictions suggested that both SVOCs (evaporated POA vapors) and IVOCs did not contribute as much as other anthropogenic precursors (e.g., alkanes, aromatics) to SOA mass concentrations in the urban areas (< 5 % and < 15 % of the total SOA respectively) as the timescales for SOA production appeared to be shorter than the timescales for transport out of the urban airshed. Comparisons of modeled IVOC concentrations with measurements of anthropogenic SOA precursors in southern California seemed to imply that IVOC emissions were underpredicted in our updated model by a factor of 2. Correcting for the vapor wall loss artifact in chamber experiments enhanced SOA mass concentrations although the enhancement was precursor-dependent as well as NOx-dependent. Accounting for the influence of NOx using the VOC:NOx ratios resulted in better predictions of OA mass concentrations in rural/remote environments but still underpredicted OA mass concentrations in urban environments. The updated model's performance against measurements combined with the results from the sensitivity simulations suggests that the OA mass concentrations in southern California are constrained within a factor of 2. Finally, simulations performed for the year 2035 showed that, despite reductions in VOC and NOx emissions in the future, SOA mass concentrations may be higher than in the year 2005, primarily from increased hydroxyl radical (OH) concentrations due to lower ambient NO2 concentrations.

In this paper, the ventilated supercavities are studied both numerically and experimentally. A slender rod is considered as the solid body which has a sharp edged disk at the nose as a cavitator and special ports for air ventilation. The experiments are conducted in a recirculating water tunnel. The simulations are provided for two different algorithms in free-surface treatment, both using the VOF method but one using Youngs' algorithm in the advection of the free-surface and the other without. The comparison between numerical simulations and experiments show that the numerical method using Youngs' algorithm accurately simulates the physics of ventilated cavitation phenomena such as the cavity shape, the gas leakage and the re-entrant jet.

In the present work, a steady-state, finite difference-based computer model of heat transfer during production of lime in a rotary kiln has been developed. The model simulates calcination reaction in the solid bed region of the rotary kiln along with turbulent convection of gas, radiation heat exchange among hot gas, refractory wall and the solid surface, and conduction in the refractory wall. The solids flow countercurrent to the gas. The kiln is divided into axial segments of equal length. The mass and energy balances of the solid and gas in an axial segment are used to obtain solids and gas temperature at the exit of that segment. Thus, a marching type of solution proceeding from the solids inlet to solids outlet arises. To model the calcination of limestone, shrinking core model with surface reaction rate control has been used. The output data consist of the refractory wall temperature distributions, axial solids and gas temperature distributions, axial percent calcination profile, and kiln length. The kiln length predicted by the present model is 5.74 m as compared to 5.5 m of the pilot kiln used in the experimental study of Watkinson and Brimacombe (1982, Watkinson, A.P. and Brimacombe, J. K., “Limestone Calcination in a Rotary Kiln,” Metallurgical Transactions B, Vol. 13B, pp. 369–378). The other outputs have been also satisfactorily validated with the aforementioned experimental results. A detailed parametric study lent a good physical insight into the lime making process and the kiln wall temperature distributions.

This paper provides embedded, reflective practice-based insight arising from my experience collaborating to produce online and print-on-demand editions of a magazine showcasing the photography of members of haphazart! Contemporary Abstracts group (hereafter referred to as haphazart!). The group’s online visual, textual and activity-based practices via the photo sharing social networking site Flickr are portrayed as achieving cohesive visual identity. Stylistic analysis of pictures in support of this claim is not attempted. Rather negotiation, that Elliot has previously described in M/C Journal as innate in collaboration, is identified as the unifying factor. However, the collaborators’ adherence to Flickr’s communication platform proves problematic in the editorial context. Some technical incoherence with possible broader cultural implications is encountered during the process of repurposing images from screen to print. A Scan of Relevant Literature The photographic gaze perceives and captures objects which seem to ‘carry within them ready-made’ a work of art. But the reminiscences of the gaze are only made possible by knowing and associating with groups that define a tradition. The list of valorised subjects is not actually defined with reference to a culture, but rather by familiarity with a limited group. (Chamboredon 144) As part of the array of socio-cultural practices afforded by Web 2.0 interoperability, sites of produsage (Bruns) are foci for studies originating in many disciplines. Flickr provides a rich source of data that researchers interested in the interface between the technological and the social find useful to analyse. Access to the Flickr application programming interface enables quantitative researchers to observe a variety of means by which information is propagated, disseminated and shared. Some findings from this kind of research confirm the intuitive. For example, Negoecsu et al. find that “a large percentage of users engage in sharing with groups and that they do so significantly” ("Analyzing Flickr Groups" 425). They suggest that Flickr’s Groups feature appears to “naturally bring together two key aspects of social media: content and relations.” They also find evidence for what they call hyper-groups, which are “communities consisting of groups of Flickr groups” ("Flickr Hypergroups" 813). Two separate findings from another research team appear to contradict each other. On one hand, describing what they call “social cascades,” Cha et al. claim that “content in the form of ideas, products, and messages spreads across social networks like a virus” ("Characterising Social Cascades"). Yet in 2009 they claim that homocity and reciprocity ensure that “popularity of pictures is localised” ("Measurement-Driven Analysis"). Mislove et al. reflect that the affordances of Flickr influence the growth patterns they observe. There is optimism shared by some empiricists that through collation and analysis of Flickr tag data, the matching of perceptual structures of images and image annotation techniques will yield ontology-based taxonomy useful in automatic image annotation and ultimately, the Semantic Web endeavour (Kennedy et al.; Su et al.; Xu et al.). Qualitative researchers using ethnographic interview techniques also find Flickr a valuable resource. In concluding that the photo sharing hobby is for many a “serious leisure” activity, Cox et al. propose that “Flickr is not just a neutral information system but also value laden and has a role within a wider cultural order.” They also suggest that “there is genuinely greater scope for individual creativity, releasing the individual to explore their own identity in a way not possible with a camera club.” Davies claims that “online spaces provide an arena where collaboration over meanings can be transformative, impacting on how individuals locate themselves within local and global contexts” (550). She says that through shared ways of describing and commenting on images, Flickrites develop a common criticality in their endeavour to understand images, each other and their world (554).From a psychologist’s perspective, Suler observes that “interpersonal relationships rarely form and develop by images alone” ("Image, Word, Action" 559). He says that Flickr participants communicate in three dimensions: textual (which he calls “verbal”), visual, and via the interpersonal actions that the site affords, such as Favourites. This latter observation can surely be supplemented by including the various games that groups configure within the constraints of the discussion forums. These often include submissions to a theme and voting to select a winning image. Suler describes the place in Flickr where one finds identity as one’s “cyberpsychological niche” (556). However, many participants subscribe to multiple groups—45.6% of Flickrites who share images share them with more than 20 groups (Negoescu et al., "Analyzing Flickr Groups" 420). Is this a reflection of the existence of the hyper-groups they describe (2009) or, of the ranging that people do in search of a niche? It is also probable that some people explore more than a singular identity or visual style. Harrison and Bartell suggest that there are more interesting questions than why users create media products or what motivates them to do so: the more interesting questions center on understanding what users will choose to do ultimately with [Web2.0] capabilities [...] in what terms to define the success of their efforts, and what impact the opportunity for individual and collaborative expression will have on the evolution of communicative forms and character. (167) This paper addresseses such questions. It arises from a participatory observational context which differs from that of the research described above. It is intended that a different perspective about online group-based participation within the Flickr social networking matrix will avail. However, it will be seen that the themes cited in this introductory review prove pertinent. Context As a university teacher of a range of subjects in the digital media field, from contemporary photomedia to social media to collaborative multimedia practice, it is entirely appropriate that I embed myself in projects that engage, challenge and provide me with relevant first-hand experience. As an academic I also undertake and publish research. As a practicing new media artist I exhibit publically on a regular basis and consider myself semi-professional with respect to this activity. While there are common elements to both approaches to research, this paper is written more from the point of view of ‘reflective practice’ (Holmes, "Reconciling Experimentum") rather than ‘embedded ethnography’ (Pink). It is necessarily and unapologetically reflexive. Abstract Photography Hyper-Group A search of all Flickr groups using the query “abstract” is currently likely to return around 14,700 results. However, only in around thirty of them does the group name, its stated rules and, the stream of images that flow through the pool arguably reflect a sense of collective concept and aesthetic that is coherently abstract. This loose complex of groups comprises a hyper-group. Members of these groups often have co-memberships, reciprocal contacts, and regularly post images to a range of groups and comment on others’ posts to be found throughout. Given that one of Flickr’s largest groups, Black and White, currently has around 131,150 members and hosts 2,093,241 items in its pool, these abstract special interest groups are relatively small. The largest, Abstract Photos, has 11,338 members and hosts 89,306 items in its pool. The group that is the focus of this paper, haphazart!, currently has 2,536 members who have submitted 53,309 items. The group pool is more like a constantly flowing river because the most recently added images are foremost. Older images become buried in an archive of pages which cannot be reverse accessed at a rate greater than the seven pages linked from a current view. A member’s presence is most immediate through images posted to a pool. This structural feature of Flickr promotes a desire for currency; a need to post regularly to maintain presence. Negotiating Coherence to the Abstract The self-managing social dynamics in groups has, as Suler proposes to be the case for individuals, three dimensions: visual, textual and action. A group integrates the diverse elements, relationships and values which cumulatively constitute its identity with contributions from members in these dimensions. First impressions of that identity are usually derived from the group home page which consists of principal features: the group name, a selection of twelve most recent posts to the pool, some kind of description, a selection of six of the most recent discussion topics, and a list of rules (if any). In some of these groups, what is considered to constitute an abstract photographic image is described on the group home page. In some it is left to be contested and becomes the topic of ongoing forum debates. In others the specific issue is not discussed—the images are left to speak for themselves. Administrators of some groups require that images are vetted for acceptance. In haphazart! particular administrators dutifully delete from the pool on a regular basis any images that they deem not to comply with the group ethic. Whether reasons are given or not is left to the individual prosecutor. Mostly offending images just disappear from the group pool without trace. These are some of the ways that the coherence of a group’s visual identity is established and maintained. Two groups out of the abstract photography hyper-group are noteworthy in that their discussion forums are particularly active. A discussion is just the start of a new thread and may have any number of posts under it. At time of writing Abstract Photos has 195 discussions and haphazart! — the most talkative by this measure—has 333. Haphazart! invites submissions of images to regularly changing themes. There is always lively and idiosyncratic banter in the forum over the selection of a theme. To be submitted an image needs to be identified by a specific theme tag as announced on the group home page. The tag can be added by the photographer themselves or by anyone else who deems the image appropriate to the theme. An exhibition process ensues. Participant curators search all Flickr items according to the theme tag and select from the outcome images they deem to most appropriately and abstractly address the theme. Copies of the images together with comments by the curators are posted to a dedicated discussion board. Other members may also provide responses. This activity forms an ongoing record that may serve as a public indicator of the aesthetic that underlies the group’s identity. In Abstract Photos there is an ongoing discussion forum where one can submit an image and request that the moderators rule as to whether or not the image is ‘abstract’. The same group has ongoing discussions labelled “Hall of Appropriate” where worthy images are reposted and celebrated and, “Hall of Inappropriate” where images posted to the group pool have been removed and relegated because abstraction has been “so far stretched from its definition that it now resides in a parallel universe” (Askin). Reasons are mostly courteously provided. In haphazart! a relatively small core of around twelve group members regularly contribute to the group discussion board. A curious aspect of this communication is that even though participants present visually with a ‘buddy icon’ and most with a screen name not their real name, it is usual practice to address each other in discussions by their real Christian names, even when this is not evident in a member’s profile. This seems to indicate a common desire for authenticity. The makeup of the core varies from time to time depending on other activities in a member’s life. Although one or two may be professionally or semi-professionally engaged as photographers or artists or academics, most of these people would likely consider themselves to be “serious amateurs” (Cox). They are internationally dispersed with bias to the US, UK, Europe and Australia. English is the common language though not the natural tongue of some. The age range is approximately 35 to 65 and the gender mix 50/50. The group is three years old. Where Do We Go to from Here? In early January 2009 the haphazart! core was sparked into a frenzy of discussion by a post from a member headed “Where do we go to from here?” A proposal was mooted to produce a ‘book’ featuring images and texts representative of the group. Within three days a new public group with invited membership dedicated to the idea had been established. A smaller working party then retreated to a private Flickr group. Four months later Issue One of haphazart! magazine was available in print-on-demand and online formats. Following however is a brief critically reflective review of some of the collaborative curatorial, editorial and production processes for Issue Two which commenced in early June 2009. Most of the team had also been involved with Issue One. I was the only newcomer and replaced the person who had undertaken the design for Issue One. I was not provided access to the prior private editorial ruminations but apparently the collaborative curatorial and editorial decision-making practices the group had previously established persisted, and these took place entirely within the discussion forums of a new dedicated private Flickr group. Over a five-month period there were 1066 posts in 54 discussions concerning matters such as: change of format from the previous; selection of themes, artists and images; conduct of and editing of interviews; authoring of texts; copyright and reproduction. The idiom of those communications can be described as: discursive, sporadic, idiosyncratic, resourceful, collegial, cooperative, emphatic, earnest and purposeful. The selection process could not be said to follow anything close to a shared manifesto, or articulation of style. It was established that there would be two primary themes: the square format and contributors’ use of colour. Selection progressed by way of visual presentation and counter presentation until some kind of consensus was reached often involving informal votes of preference. Stretching the Limits of the Flickr Social Tools The magazine editorial collaborators continue to use the facilities with which they are familiar from regular Flickr group participation. However, the strict vertically linear format of the Flickr discussion format is particularly unsuited to lengthy, complex, asynchronous, multithreaded discussion. For this purpose it causes unnecessary strain, fatigue and confusion. Where images are included, the forums have set and maximum display sizes and are not flexibly configured into matrixes. Images cannot readily be communally changed or moved about like texts in a wiki. Likewise, the Flickrmail facility is of limited use for specialist editorial processes. Attachments cannot be added. This opinion expressed by a collaborator in the initial, open discussion for Issue One prevailed among Issue Two participants: do we want the members to go to another site to observe what is going on with the magazine? if that’s ok, then using google groups or something like that might make sense; if we want others to observe (and learn from) the process - we may want to do it here [in Flickr]. (Valentine) The opinion appears socially constructive; but because the final editorial process and production processes took place in a separate private forum, ultimately the suggested learning between one issue and the next did not take place. During Issue Two development the reluctance to try other online collaboration tools for the selection processes requiring visual comparative evaluation of images and trials of sequencing adhered. A number of ingenious methods of working within Flickr were devised and deployed and, in my opinion, proved frustratingly impractical and inefficient. The digital layout, design, collation and formatting of images and texts, all took place on my personal computer using professional software tools. Difficulties arose in progressively sharing this work for the purposes of review, appraisal and proofing. Eventually I ignored protests and insisted the team review demonstrations I had converted for sharing in Google Documents. But, with only one exception, I could not tempt collaborators to try commenting or editing in that environment. For example, instead of moving the sequence of images dynamically themselves, or even typing suggestions directly into Google Documents, they would post responses in Flickr. To Share and to Hold From the first imaginings of Issue One the need to have as an outcome something in one’s hands was expressed and this objective is apparently shared by all in the haphazart! core as an ongoing imperative. Various printing options have been nominated, discussed and evaluated. In the end one print-on-demand provider was selected on the basis of recommendation. The ethos of haphazart! is clearly not profit-making and conflicts with that of the printing organisation. Presumably to maintain an incentive to purchase the print copy online preview is restricted to the first 15 pages. To satisfy the co-requisite to make available the full 120 pages for free online viewing a second host that specialises in online presentation of publications is also utilised. In this way haphazart! members satisfy their common desires for sharing selected visual content and ideas with an online special interest audience and, for a physical object of art to relish—with all the connotations of preciousness, fetish, talisman, trophy, and bookish notions of haptic pleasure and visual treasure. The irony of publishing a frozen chunk of the ever-flowing Flickriver, whose temporally changing nature is arguably one of its most interesting qualities, is not a consideration. Most of them profess to be simply satisfying their own desire for self expression and would eschew any critical judgement as to whether this anarchic and discursive mode of operation results in a coherent statement about contemporary photographic abstraction. However there remains a distinct possibility that a number of core haphazart!ists aspire to transcend: popular taste; the discernment encouraged in camera clubs; and, the rhetoric of those involved professionally (Bourdieu et al.); and seek to engage with the “awareness of illegitimacy and the difficulties implied by the constitution of photography as an artistic medium” (Chamboredon 130). Incoherence: A Technical Note My personal experience of photography ranges from the filmic to the digital (Holmes, "Bridging Adelaide"). For a number of years I specialised in facsimile graphic reproduction of artwork. In those days I became aware that films were ‘blind’ to the psychophysical affect of some few particular paint pigments. They just could not be reproduced. Even so, as I handled the dozens of images contributed to haphazart!2, converting them from the pixellated place where Flickr exists to the resolution and gamut of the ink based colour space of books, I was surprised at the number of hue values that exist in the former that do not translate into the latter. In some cases the affect is subtle so that judicious tweaking of colour levels or local colour adjustment will satisfy discerning comparison between the screenic original and the ‘soft proof’ that simulates the printed outcome. In other cases a conversion simply does not compute. I am moved to contemplate, along with Harrison and Bartell (op. cit.) just how much of the experience of media in the shared digital space is incomparably new? Acknowledgement Acting on the advice of researchers experienced in cyberethnography (Bruckman; Suler, "Ethics") I have obtained the consent of co-collaborators to comment freely on proceedings that took place in a private forum. 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