Etude de la recirculation des gaz carter et des gaz d échappement dans les moteurs à combustion interne

Ce travail de thèse porte sur l étude théorique et expérimentale des circuits de recirculation des gaz carter et des gaz d échappement dans les moteurs à combustion interne. La recirculation des gaz d'échappement, ou EGR consiste à rediriger une partie des gaz d'échappement des moteurs à combustion interne dans le collecteur d'admission. La recirculation de ces gaz d échappement permet de diminuer les émissions des oxydes d azote. Les séparateurs centrifuges présents dans le circuit de recirculation des gaz carter permettent de séparer les particules d huile du gaz pour diminuer la consommation d huile et prote ger les pièces de la ligne d admission d air contre l encrassement. Une nouvelle technique de mesure simultanée de la granulométrie et de la vitesse des particules en deux directions dans un champ de quelques centimètres carrés a été mise au point. Des mesures ont été réalisées sur un banc d organe développé pour reproduire les gaz carter et le circuit de ventilation du carter. Un moyen de calcul de l efficacité de séparation et de la perte de charge des décanteurs à hélice a été développé. Les résultats théoriques ont été validés par des résultats expérimentaux. Un nouveau concept de décanteur centrifuge hélice à géométrie variable adapté à notre application a été développé dans cette étude. Ce concept permet de réduire jusqu à cinq fois la consommation d huile provenant des gaz carter. Pour étudier le mélange air/EGR, dans le collecteur d'admission, une nouvelle technique de mesure non intrusive a été développée dans cette étude. Cette technique permet d évaluer l homogénéité du mélange air/EGR et de mesurer la répartition des gaz EGR cylindre à cylindre.In this project a combination of experiments and simulations is used to study the recirculation of the blow by gas and the exhaust gas in internal combustion engines. These systems were developed to reduce pollutant emissions. Exhaust Gas Recirculation EGR reduces flame temperature, thereby reducing nitrogen oxide (NOx) emissions. Centrifugal oil mist separators present in the crankcase ventilation systems are used to separate oil particles from blow by gas in order to reduce oil consumption and protect the air intake line. A new simultaneous measurement technique of particles sizes and velocities in a field of a few square centimetres was developed. Measurements have been carried out on an experimental set-up developed to simulate the blow by gas and the engine crankcase ventilation system. Analytical software was developed to predict the efficiency and the pressure drop of the swirl tube separator. Theoretical results were compared and validated by experimental results. A new concept of oil mist separator variable swirl tube separator adapted to our application was developed. This concept reduces five times the oil consumption coming from the blow by gas in internal combustion engines. To study the air/EGR mixture in the air intake manifold, before the combustion chamber, a new non-intrusive measurement technique was developed in this study. This technique evaluates the homogeneity of the air/EGR mixture and measures the EGR cylinder to cylinder distribution.NANTERRE-BU PARIS10 (920502102) / SudocSudocFranceF

Cairsens NO2: A Miniature Device Dedicated to the Indicative Measurement of Nitrogen Dioxide in Ambient Air

This paper reports the study of data quality of Cairsens NO2 environmental sensors. In order to evaluate sensors performances, the investigation was performed through: a prospective follow-up of short-term and long terms drifts, the evaluation of the effects of environmental conditions upon sensors measurements as well as the evaluation of the ozone-filter lifetime. In this purpose, a dedicated test bench has been developed to expose sensors to a fixed concentration of ozone while recording sensors response

Application of ODEMS (Odorant Dispersion and Emissions Monitoring System) to Measure Odorous Emissions from Composting Plant

International audienceOdour annoyance represents a very important issue of societal and industrial perspective. It can be due to the intrinsic character of the odour, its frequency and the moment of the perception. Location of industries depends on their odour acceptability in the neighbourhood. As 13 to 20% of the population in European countries would be annoyed by environmental odours, stringent regulations are being enforced for odor monitoring and recently, several works have been carried out to determine suitable and valuable strategies/methods to limit odor annoyance. Industrial and agricultural activities generate atmospheric pollution and olfactive nuisances due to the emission of a complex mixture of volatile compounds. Hydrogen sulphide (H2S) and ammonia (NH3) are clearly identified within composting plants (Cabrol et al, 2012) and due to their high olfactory impact, have to be monitored as mentioned in a report of the French Environmental and Energy Management Agency (ADEME, 2012). ODEMS is a system composed by a network of miniature and autonomous sensors combined with reversed dispersion (Figure 1) and dispersion (Figure 2) modelling systems and enable to provide reliable spatial and temporal information down to the low ppbv level. The miniaturized cost-effective sensors Cairsens are based on amperometric detection and are developed by Cairpol company. Ammonia and hydrogen sulfide sensors have been deployed within a composting plant for determining the odorous sources and evaluating the real impact on the neighbourhood. After a period of data collection, considering weather conditions, this study revealed that this system is also able to predict the impact of a site-specific activity

A Broadband Cavity-Enhanced Absorption Spectrometer for Simultaneous measurements of NO2 and particulate matter

International audienceA novel instrument based on broadband cavity enhanced absorption spectroscopy has been developed using a supercontinuum broadband light source, which showcases its ability in simultaneous measurements of the concentration of NO2 and the extinction of particulate matter (PM). Side-by-side intercomparison was carried out with the reference NOx analyzer for NO2 and OPC-N2 particle counter for particulate matter, which shows a good linear correlation with r2 > 0.90. Measurement limits (1σ) of the developed instrument were experimentally determined to be 230 pptv in 40 s for NO2 and 1.24 Mm-1 for the PM extinction in 15 s, respectively.This work provides a promising method in simultaneously monitoring atmospheric gaseous compounds and particulate matter, which would further advance our understanding on gas-particle heterogeneous interactions in the context of climate change and air quality.Experimental details and the preliminary results will be discussed and presented. AcknowledgmentsThe authors thank the financial supports from the French national research agency (ANR) under the MABCaM (ANR-16-CE04-0009), the CaPPA (ANR-10-LABX-005) contracts, the CPER ECRIN program, and the EU H2020-ATMOS project

Novel Broadband Cavity-Enhanced Absorption Spectrometer for Simultaneous Measurements of NO2 and Particulate Matter

International audienceA novel instrument based on broadband cavity-enhanced absorption spectroscopy has been developed using a supercontinuum broadband light source, which showcases its ability in simultaneous measurements of the concentration of NO2 and the extinction of particulate matter. Side-by-side intercomparison was carried out with the reference NOx analyzer for NO2 and OPC-N2 particle counter for particulate matter, which shows a good linear correlation with r2 > 0.90. The measurement limits (1σ) of the developed instrument were experimentally determined to be 230 pptv in 40 s for NO2 and 1.24 Mm−1 for the extinction of particulate matter in 15 s. This work provides a promising method in simultaneously monitoring atmospheric gaseous compounds and particulate matter, which would further advance our understanding on gas−particle heterogeneous interactions in the context of climate change and air quality

Assessing Continuing Education Practices and Preferences amongst Lebanese Hospital Pharmacists

Background: Continuing education (CE) is an international tool that requires lifelong active participation in learning activities allowing the pharmacist to stay a major player among others. In 2014 the CE program was introduced to the pharmacists licensed in Lebanon as a mandatory requirement for re-licensure. In the absence of guidelines regarding the quality and quantity of CE programs, behavioral resistance to precipitate in the CE programs might be encountered among the pharmacists. Objective: The objective of this study is to assess the perceptions of pharmacists working in Lebanese hospitals on the continuing education preferences. The advantage of this program is to collect information that would help the Order of Pharmacy in Lebanon to upgrade the CE program in a way that is more acceptable and convenient for the pharmacists. Methods: A cross-sectional study was carried out in 2016, using a proportionate random sample of Lebanese hospital pharmacies from all governorates in Lebanon. A structured questionnaire was distributed to all hospital pharmacies in Lebanon. Descriptive statistics were calculated for all study variables. This includes the mean and standard deviation for continuous measures, counts and percentages for categorical variables Results: A total of 107 (53.5%) participants completed the questionnaires. The majority of participants were from Beirut and Mount Lebanon. The percentage of participants working at private hospitals was (68.2%).The majority of participants who completed the questionnaire (86.2%) agreed that continuing education programs affects their way of practice and increases their knowledge. Their preferred CE types to be used in the future were the computer based ones (60.6%), interactive workshops (45.5%) and printed materials (44.9%). Their considerations for selecting the CE type is based on their interest in the topic (80.6%), the ease of access to print or online material (77.2%), or the convenience of being offered during an event (67.1%). Participants noted that barriers to attend live CEs were mainly work responsibilities (76%), travel distance (65.6%), family commitments (48.4%) and scheduling (40.6%). Conclusions: Lebanese hospital pharmacists are highly committed to CE. They consider it a practical tool for career development and advancement

Novel Broadband Cavity-Enhanced Absorption Spectrometer for Simultaneous Measurements of NO₂ and Particulate Matter

A novel instrument based on broadband cavity-enhanced absorption spectroscopy has been developed using a supercontinuum broadband light source, which showcases its ability in simultaneous measurements of the concentration of NO2 and the extinction of particulate matter. Side-by-side intercomparison was carried out with the reference NOx analyzer for NO2 and OPC-N2 particle counter for particulate matter, which shows a good linear correlation with r2 > 0.90. The measurement limits (1σ) of the developed instrument were experimentally determined to be 230 pptv in 40 s for NO2 and 1.24 Mm–1 for the extinction of particulate matter in 15 s. This work provides a promising method in simultaneously monitoring atmospheric gaseous compounds and particulate matter, which would further advance our understanding on gas–particle heterogeneous interactions in the context of climate change and air quality

The prognostic value of serum procalcitonin in acute obstructive pyelonephritis

International audiencePurpose To evaluate the prognostic value of procalcitonin (PCT) in the occurrence of infectious complications in the management of acute obstructive pyelonephritis (AOP) compared with other biological parameters (leucocyte count, C-reactive protein [CRP]). Methods We conducted a retrospective study including patients who were treated for AOP and performed serum PCT tests in our center between January 1, 2017 and December 31, 2017. Upper urinary tract obstruction was confirmed by either ultrasound or CT urography. Clinical examinations and laboratory tests including leukocyte count, CRP, urine and blood cultures, and serum PCT measurements were performed in the emergency unit. Treatment included early renal decompression using indwelling ureteral stents or nephrostomy and empiric antibiotic therapy. The primary endpoint was occurrence of severe sepsis (SS), a composite criterion including urosepsis and/or septic shock and/or admission to the intensive care unit (ICU) and/or death. Results A total of 110 patients (median age: 61 years) were included, of whom 56.3% were female. SS occurred in 39 cases (35.4%). Multivariate regression analysis showed that serum PCT (OR 1.08; 95% CI 1.03-1.17;p = 0.01), CRP (OR 1.007; 95% CI 1.001-1.015;p = 0.03), and diabetes mellitus (OR 5.1; 95% CI 1.27-27.24;p = 0.04) were independent predictors for SS. Serum PCT was the biological marker associated with the highest accuracy to predict SS (ROC 0.912 (95% CI 0.861-0.962) and was superior to CRP (p 1.12 mu g/L could help physicians to identify high-risk patients who could benefit from early and aggressive management in collaboration with intensive care specialists

LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 2: First results from balloon and unmanned aerial vehicle flights

International audienceIn the companion (Part I) paper, we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter), based on scattering measurements at angles of 12 and 60 •. That allows for some typology identification of particles (droplets, carbonaceous, salts, and mineral dust) in addition to size-segregated counting in a large diameter range from 0.2 µm up to possibly more than 100 µm depending on sampling conditions (Renard et al., 2016). Its capabilities overpass those of preceding optical particle counters (OPCs) allowing the characterization of all kind of aerosols from submicronic-sized absorbing carbonaceous particles in polluted air to very coarse particles (> 10–20 µm in diameter) in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons , on-board unmanned aerial vehicles (UAVs) and at Published by Copernicus Publications on behalf of the European Geosciences Union. 3674 J.-B. Renard et al.: LOAC: a counter/sizer for ground-based and balloon measurements – Part 2 ground level. We illustrate here the first LOAC airborne results obtained from a UAV and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i) tethered balloons deployed in urban environments in Vi-enna (Austria) and Paris (France), (ii) pressurized balloons drifting in the lower troposphere over the western Mediter-ranean (during the Chemistry-Aerosol Mediterranean Experiment – ChArMEx campaigns), (iii) meteorological sounding balloons launched in the western Mediterranean region (ChArMEx) and from Aire-sur-l'Adour in southwestern France (VOLTAIRE-LOAC campaign). More focus is put on measurements performed in the Mediterranean during (ChArMEx) and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes

LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 1: Principle of measurements and instrument evaluation

International audienceThe study of aerosols in the troposphere and in the stratosphere is of major importance both for climate and air quality studies. Among the numerous instruments available, optical aerosol particles counters (OPCs) provide the size distribution in diameter range from about 100 nm to a few tens of µm. Most of them are very sensitive to the nature of aerosols, and this can result in significant biases in the retrieved size distribution. We describe here a new versatile optical particle/sizer counter named LOAC (Light Optical Aerosol Counter), which is light and compact enough to perform measurements not only at the surface but under all kinds of balloons in the troposphere and in the stratosphere. LOAC is an original OPC performing observations at two scattering angles. The first one is around 12°, and is almost insensitive to the refractive index of the particles; the second one is around 60° and is strongly sensitive to the refractive index of the particles. By combining measurement at the two angles, it is possible to retrieve the size distribution between 0.2 and 100 µm and to estimate the nature of the dominant particles (droplets, carbonaceous, salts and mineral particles) when the aerosol is relatively homogeneous. This typology is based on calibration charts obtained in the laboratory. The uncertainty for total concentrations measurements is ±20% when concentrations are higher than 1 particle cm-3 (for a 10 min integration time). For lower concentrations, the uncertainty is up to about ±60% for concentrations smaller than 10-2 particle cm-3. Also, the uncertainties in size calibration are ±0.025 μm for particles smaller than 0.6 μm, 5% for particles in the 0.7-2 μm range, and 10% for particles greater than 2 μm. The measurement accuracy of submicronic particles could be reduced in a strongly turbid case when concentration of particles > 3 µm exceeds a few particles cm-3. Several campaigns of cross-comparison of LOAC with other particle counting instruments and remote sensing photometers have been conducted to validate both the size distribution derived by LOAC and the retrieved particle number density. The typology of the aerosols has been validated in well-defined conditions including urban pollution, desert dust episodes, sea spray, fog, and cloud. Comparison with reference aerosol mass monitoring instruments also shows that the LOAC measurements can be successfully converted to mass concentrations