Caractérisation du comportement dynamique d’un circuit d’admission. Incidence sur le remplissage d’un moteur à combustion interne suralimenté

This Ph.D. thesis studies the unsteady behavior of pressure waves at the intake of an internal combustion engine using “frequency-domain” solutions and methodologies as well as the influence of said waves on the filling of a turbocharged engine. These pressure waves are generated by the pistons and valves that behave much like an acoustic source due to engine’s reciprocating operation. The methodology is developed with two experimental systems: the shock tube and the Dynamic Bench. Transfer matrices of charge air coolers (CAC) are determined following a mass flow excitation on the Dynamic Bench or directly at the engine’s intake. The transfer matrices have to be accurate for frequencies corresponding to the engine’s harmonics and the effects of a pulsating flow as well as marge pressure amplitudes have to be taken into account. The influence of the geometry and heat transfer on the reflection coefficient through the CAC is also investigated. The distance separating the CAC from the intake valves is experimentally modified in a way to analyze its influence on engine filling and transient response. The transfer matrix of the CAC is coupled to an engine simulation code GT-Power using a Simulink model that exchange frequency and time domain information at each time step and replace the one-dimensional modeling of the CAC. This set of methodologies is validated against engine test bench experimental data in terms of pressure andmass flow both in the frequency and time domains.Cette thèse étudie le comportement instationnaire des ondes de pression à l’admission d’un moteur à combustion interne avec des méthodes dites «fréquentielles » ainsi que leur influence sur le remplissage en air d’un moteur suralimenté. Ces ondes sont générées par les soupapes et pistons qui se comportent comme des sources acoustiques à cause de leur fonctionnement alternatif. Les ondes de pression ont une influence du premier ordre sur les paramètres et le fonctionnement du moteur. La méthodologie fréquentielle est développée avec deux dispositifs expérimentaux : le tube à choc et le Banc Dynamique. Des matrices de transfert des refroidisseurs d’air de suralimentation (RAS) sont déterminées suite à une excitation de débit masse sur le Banc Dynamique ou directement à l’admission du moteur. Les matrices doivent être précises pour lesharmoniques moteur relatives au remplissage et prennent en compte les effets d’un débit pulsé et des variations de grandes amplitudes. D’autre part, l’influence de la géométrie et des transferts thermiques sur le coefficient de réflexion à travers le RAS est étudiée. La distance entre le RAS et les soupapes est expérimentalement modifiée sur le banc moteur et son influence sur le remplissage moteur analysée. La matrice de transfert du RAS est couplée à un code de calcul moteur GT-Power sous la forme d’un modèle dans Simulink qui échange des informations fréquentielles et temporelles à chaque pas de temps et remplace alors la modélisation unidimensionnelle. L’ensemble des méthodologies est validé sur le bancd’essais moteur en terme de pression et de débit masse puis une comparaison avec des résultats expérimentaux obtenus a été effectuée

Bit Error Rate Performance of In-vivo Radio Channel Using Maximum Likelihood Sequence Estimation

In this paper we present the Bit Error Rate (BER) performance of equalizers using in-vivo channel response measured using Vector Network Analyzer (VNA). Including the use of a Bandwidth (BW) of 50 MHz in the simulations, the results are compared with multiple equalizers and it is shown that Maximum Likelihood Sequence Estimation (MLSE) equalizer outperformed the rest of the equalizers including linear equalizers Least Mean Square (LMS) and Recursive least sequence (RLS) and non-linear equalizer Decision Feedback Equalizer (DFE). The BER performance using MLSE showed significant improvement by improving the BER and outperforming the linear equalizer from 10 −2 to 10 −6 and DFE from 10 −4 to 10 −6 at Eb/No=14 dB for in vivo radio communication channel at ultra wideband (UWB) frequencies. Furthermore, the un-equalized and equalized channel frequency response spectrum is also part of this article which presents the overall improvement between the two spectrums

Investigation of enhanced double weight code in point to point access networks

© 2020 Published under licence by IOP Publishing Ltd. In this paper, an investigation and evaluation to enhanced double weight (EDW) code is performed, a new technique for code structuring and building using modified arithmetical model has been given for the code in place of employing previous technique based on Trial Inspections. Innovative design has been employed for the code into P2P networks using diverse weighted EDW code to be fitting into optical CDMA relevance applications. A new developed relation for EDW code is presented, the relation is based on studying and experimenting the effect of input transmission power with code weight, and the relation developed using numerical analysis method. This relation makes the estimation for the system input power needed more efficient. The results of the code has been explained by eye diagram and parametric illustrations from the simulated results. The result shows a magnificent performance of the code during high number of users and weight. On the other hand, the relation developed for power measurement helps to prevent power loss and consumption

Investigation the nonlinear optical properties of silver nanoparticles using femtosecond laser

© 2020 Published under licence by IOP Publishing Ltd. In this research, the fabrication of silver nanoparticles and experimental nonlinear response (NLO). The fabrication of the silver nanoparticles has been done using E-Beam evaporation on a glass substrate (Ag-NPs) and investigation of their nonlinear optical response (NLO). The silver nanoparticles was evaluated by optical spectrum (UV-Vis) that shows localized surface Plasmon band at 375 nm. The experiment shows the nonlinear absorption and nonlinear refraction effect of silver nanoparticles, the silver nanoparticles is analysed by Z-Scan technique using a femtoseconds laser with 800 nm wavelength. The result shows the nonlinear absorption (NLA) is at 4.8710-4cmW-1, while (NLR) is at 7.9410-9cmW-1

The impact of technological innovation on building a sustainable city

By 2050, the population living in major cities, especially in developing countries, will have increased twofold. With the increasing majority of the population occurring in urban areas, it is crucial to focus on how technological innovation can help to deliver a sustainable future. A sustainable city strives to create a sustainable living environment through the use of technology. Thus, the main objective of this paper is to review the impact of technological innovation on building a more sustainable city. Technological innovation has changed the overall effectiveness and benevolence over time and with regard to sustainability. A sustainable city involves development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Sustainable development encompasses all aspects of environmental stewardship, social development, and economic progress

Simple scoring system to predict in-hospital mortality after surgery for infective endocarditis

BACKGROUND: Aspecific scoring systems are used to predict the risk of death postsurgery in patients with infective endocarditis (IE). The purpose of the present study was both to analyze the risk factors for in-hospital death, which complicates surgery for IE, and to create a mortality risk score based on the results of this analysis. METHODS AND RESULTS: Outcomes of 361 consecutive patients (mean age, 59.1\ub115.4 years) who had undergone surgery for IE in 8 European centers of cardiac surgery were recorded prospectively, and a risk factor analysis (multivariable logistic regression) for in-hospital death was performed. The discriminatory power of a new predictive scoring system was assessed with the receiver operating characteristic curve analysis. Score validation procedures were carried out. Fifty-six (15.5%) patients died postsurgery. BMI >27 kg/m2 (odds ratio [OR], 1.79; P=0.049), estimated glomerular filtration rate 55 mm Hg (OR, 1.78; P=0.032), and critical state (OR, 2.37; P=0.017) were independent predictors of in-hospital death. A scoring system was devised to predict in-hospital death postsurgery for IE (area under the receiver operating characteristic curve, 0.780; 95% CI, 0.734-0.822). The score performed better than 5 of 6 scoring systems for in-hospital death after cardiac surgery that were considered. CONCLUSIONS: A simple scoring system based on risk factors for in-hospital death was specifically created to predict mortality risk postsurgery in patients with IE

Fabrication and characterization of metal nanostructures and graphene nanolayers and their application in optical sensing / Mezher H Mezher

We present a study of optical characteristics of metal and graphene oxide nano-layers and their application in optical sensing. The nano-layers are coated using different approaches such as electron beam evaporation, electrochemical deposition and drop casting technique. Gold and silver nanoparticle layers were fabricated using electron beam evaporation followed by subsequent thermal annealing at different temperature and duration to achieve de-wetting of the metal thin film. Morphological analysis was carried out to study the shape and size of the produced nanoparticles. The gold and silver nanoparticles have sizes ranging from 11 nm to 45 nm and 15 nm to 54 nm, respectively. Meanwhile, bilayer Au/Ag-NPs have also been fabricated with particle size in the range between 23nm and 26 nm. On the other hand, the effects of nanostructures were studied using silver micro-flowers (Ag-MFs) with sizes of ~150-500 nm and platinum ‗dome-like‘ nanostructures (Pt-NSs). Absorption spectroscopy was carried out to study the Surface Plasmon Resonance (SPR) of the nanoparticle layers. The shape and size of the nanoparticles are observed to affect the shifting of SPR wavelengths. Nonlinear optical properties was obtained for different structures of nano-layers using Z-scan technique. The nonlinear refractive index and nonlinear absorption coefficient of the nano-layers were determined. The Au-NPs show increase in the NLA and NLR with the increase in nanoparticle size. Meanwhile, The Au/Ag-NPs exhibit NLA and NLR between Au-NPs and Ag-NPs. The nonlinear optical properties of Ag-MFs with increase the size of microflower show increase in the NLA and NLR. Due to thermal effect, nonlinear absorption and nonlinear refraction index are not constant values and depend on the incident intensity. Increases the intensity that apply on Pt-NSs show reduce NLA and NLR value and also for nitrogen doped graphene show reduce in NLA and NLR when increase the incident intensity. From the state of increasing the incident intensity can decreasing in the NLR due to thermal nonlinearity. The GO show increase in NLA and NLR with the increase in thickness. Selected nano layers (Platinum and Graphene oxide) are applied on optical waveguides for detection the water content in transformer oil. Pt-NPs coated planar waveguide sensor shows the sensitivity to dissolved water in transformer oil of -0.561 dB/ppm, while Pt-NPs coated D-Fiber sensor shows a sensitivity of -0.88 dB/ppm. GO have been coated on planar waveguide and D-Fiber to measure the water content in transformer oil. Depending on the GO coating thickness, the sensitivity range from 0.3 dB/ppm of water content in transformer oil to 1.86 dB/ppm of water content in transformer oil. The stability of the sensor output is inversely proportionate to the sensitivity, meaning there is a compromise between the two parameters when considering devising optical sensors in this configuration. The GO-coated waveguide sensor is further tested with continuous varying water content in transformer oil using a fluidic channel structure, and the result shows that the sensor is able to discern changes in water content in transformer oil in simulated environment

Graphene oxide-based optical waveguide for moisture sensing in transformer oil

We report on moisture detection in transformer oil based on an optical waveguide fabricated using graphene oxide (GO). The SU-8 polymer channel waveguide was coated by GO film, using a drop-casting technique. Here, for the polarized light, high absorption of transverse electric (TE) was achieved for the proposed sensor at wavelength 1550 nm. Changes in TE-polarized light absorption by the device were measured at varying water contents. Experiments were carried out for water contents in oil in the range of 16–21 ppm as well as immiscible (free) water in oil. Our observations showed a difference in the results trend obtained for different relative water contents. The TE-transmission power increased linearly with higher water content in transformer oil. A power change of +0.90 dB/ppm of water content in transformer oil was measured within the range tested. A simulation analysis using the finite element method FEM was also carried out. The proposed sensing mechanism can be used under these sensing conditions. This approach also has a fast response time as well as high sensitivity. © 2019 Elsevier B.V