2,019 research outputs found

    Mise au point de filtres garnis de matériaux réactifs destinés au traitement des eaux usées au sein de petites installations

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    L objectif de ce travail est la mise au point de filtres garnis de laitiers d aciéries destinés au traitement du phosphore (P) des eaux usées au sein de petites installations. Deux types de laitiers on été testés: laitiers de four à arc électrique (EAF), et laitiers d'aciérie de conversion (BOF). Une approche intégrée a été suivie, avec investigations à différentes échelles: (i) Des expériences en flacons ont été réalisées pour établir les capacités de rétention du P de laitiers produits en Europe, et ainsi sélectionner les échantillons les plus adaptés pour l élimination du P; (ii)Des expériences en colonnes ont été menées pour étudier l'effet de divers paramètres, notamment la taille et la composition du laitier, sur les performances hydrauliques et épuratoires des filtres; (iii) Enfin, des expériences sur terrain ont été conduites afin d évaluer les performances hydrauliques et épuratoires de deux unités démonstration conçues pour le traitement du P au sein d un marais artificiel. Les résultats expérimentaux ont indiqué que le principal mécanisme d'élimination du P est lié à la dissolution du CaO des laitiers, suivie de la précipitation de phosphate de Ca et recristallisation en hydroxyapatite (HAP). Après 100 semaines d'alimentation avec une solution de P (concentration moyenne de P totale 10,2 mgP/L), les colonnes remplies de laitiers de petite taille (BOF6-12 mm et EAF 5-16 mm) ont retenu >98% du P total en entrée, tandis que les colonnes remplies de laitiers de grande taille (BOF 20-50 mm et EAF 20-40) ont retenu 56et 86% du P total en entrée, respectivement. Il apparaît que, plus la taille des laitiers est petite, plus la surface spécifique disponible pour la dissolution du CaO et pour l adsorption des phosphates de Ca est grande. Les expériences sur terrain ont confirmé que les laitiers sont efficaces pour le traitement du P de l'effluent d'un marais artificiel (concentration moyenne du P totale 8,3 mg P/L). Sur une période de 85 semaines d'opération, de laitiers EAF ont retenu le 36% du P total en entrée, tandis que les laitiers BOF ont retenu le 59% du P total en entrée.L efficacité de rétention du P apparaît augmenter avec la température et le temps de rétention hydraulique (HRT),très probablement parce que l'augmentation de la température et du HRT a favorisé la dissolution de la CaO et la précipitation de phosphate de Ca. Toutefois, il a été constaté que HRT >3 jours peuvent produire des pH élevés (>9), à la suite d une excessive dissolution de CaO.Cependant, les résultats des unités démonstration ont montré que, à HRT de 1-2 jours, les filtres produisent des pH élevés seulement pendant les 5 premières semaines de fonctionnement, puis les pH se stabilisent en dessous de 9. Enfin, une équation de dimensionnement sur la base des résultats expérimentaux a été proposée.This thesis aimed at developing the use of electric arc furnace steel slag (EAF-slag) and basic oxygen furnace steel slag (BOF-slag) in filters designed to upgrade phosphorus (P) removal in small wastewater treatment plants. An integrated approach was followed, with investigation at different scales: (i) Batch experiments were performed to establish an overview of the P removal capacities of steel slag produced in Europe, and then to select the most suitable samples for P removal; (ii)Continuous flow column experiments were performed to investigate the effect of various parameters including slag size and composition, and column design on treatment and hydraulic performances of lab-scale slag filters; (iii)Finally, field experiments were performed to investigate hydraulic and treatment performances of demonstration scale slag filters designed to remove P from the effluent of a constructed wetland. The experimental results indicated that the major mechanism of P removal was related toCaO-slag dissolution followed by precipitation of Caphosphate and recrystallisation into hydroxyapatite (HAP).Over 100 weeks of continuous feeding of a synthetic Psolution (mean inlet total P 10.2 mg P/L), columns filled with small-size slag (6-12 mm BOF-slag; 5-16 mm EAFslag)removed >98% of inlet total P, whereas columnsfilled with big-size slag (20-50 mm BOF-slag and 20-40mm EAF-slag) removed 56 and 86% of inlet total P,respectively. Most probably, the smaller was the size ofslag, the greater was the specific surface for CaO-slagdissolution and adsorption of Ca phosphate precipitates.Field experiments confirmed that EAF-slag and BOF-slagare efficient substrate for P removal from the effluent of aconstructed wetland (mean inlet total P 8.3 mg P/L). Overa period of 85 weeks of operation, EAF-slag removed 36%of inlet total P, whereas BOF-slag removed 59% of inlettotal P. P removal efficiencies increased with increasing temperature and void hydraulic retention time (HRTv),most probably because the increase in temperature and HRTv affected the rate of CaO dissolution and Caphosphate precipitation. However, it was found that longHRTv (>3 days) may produce high pH of the effluents(>9), as the result of excessive CaO-slag dissolution. However, the results of field experiments demonstrated that at shorter HRTv (1-2 days), slag filters produced pH that were elevated only during the first 5 weeks of operation, and then stabilized below a pH of 9. Finally, a dimensioning equation based on the experimental results was proposed.NANTES-ENS Mines (441092314) / SudocSudocFranceF

    Evaluation of Energy Recovery Potential by Anaerobic Digestion and Dark Fermentation of Residual Biomass in Colombia

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    This study provides the first overview in Colombia on energy recovery potential by anaerobic digestion (AD) and dark fermentation (DF) of three different residual biomasses: coffee mucilage (CFM), cocoa mucilage (CCM), and swine manure (SM). First, AD and DF models were developed based on the ADM1 model. Then, simulated biogas production yields were compared to experimental data to validate the models. The results of comparative simulations indicate that energy recovery potentials from biogas for the different Colombian departments range from 148 to 48,990 toe, according to the local production amounts of CFM, CCM, and SM in 2017. The study provides crucial information that can be used to assess the best design, operation mode, and locations of AD and DF plants in Colombia. The results indicate that biogas production performances and energy recovery yields improve by increasing CFM/SM and/or CCM/SM ratios of the feed, and by increasing organic load from 2 to 26 gCOD∙l−1

    Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

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    One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI

    Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

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    This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

    Search for stop and higgsino production using diphoton Higgs boson decays

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    Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top-quark (stop) and the Higgs boson (higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 inverse femtobarns of proton-proton collision data at sqrt(s) = 8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the stop mass below 360 to 410 GeV, depending on the higgsino mass

    Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

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    The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

    Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

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    A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

    MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

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    Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe
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