Articles de revues : « Injection dynamics »

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Yao, Xigui, Zhendong Zhang, Xiangdong Kong et Congbo Yin. « Dynamic Response Analysis and Structure Optimization of GDI Injector based on Mathematical Model ». International Journal of Reliability, Quality and Safety Engineering 25, n^o 02 (6 mars 2018) : 1850008. http://dx.doi.org/10.1142/s0218539318500080.

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The purpose of this research is to prevent the abnormal injection process in Gasoline Direct Injection (GDI) injector, realize accurate control of the fuel injection quantity and improve the performance of gasoline engine. The mechanical characteristics of the needle valve in a porous GDI injector is analyzed, the needle dynamics model is established, and the needle oscillation process is simulated with a mechanic-electronic-hydraulic integration method with the help of AMEsim software. The validity of the model is verified. The factors that influence the dynamics of the needle valve are analyzed. The results show that the dynamics of needle movement in GDI injector are mainly affected by the seat cone angle and the moving mass of the needle valve. The comprehensively improved structure of GDI injector is proposed based on the needle oscillation analysis. The simulation results show that the dynamic characteristics in GDI injector’s needle valve can be significantly improved with the optimized new structure. The experimental results of fuel injection flow characteristic and penetration distance show that the reliability and safety of the injector has been enhanced after structure optimization.

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Perini, Federico, Stephen Busch et Rolf Deneys Reitz. « A phenomenological rate of injection model for predicting fuel injection with application to mixture formation in light-duty diesel engines ». Proceedings of the Institution of Mechanical Engineers, Part D : Journal of Automobile Engineering 234, n^o 7 (31 janvier 2020) : 1826–39. http://dx.doi.org/10.1177/0954407019898062.

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Fuel injection rate laws are one of the most important pieces of information needed when modeling engine combustion with computational fluid dynamics. In this study, a simple phenomenological model of a common-rail injector was developed and calibrated for the Bosch CRI2.2 platform. The model requires three tunable parameter fits, making it relatively easy to calibrate and suitable for injector modeling when high-fidelity information about the internal injector’s geometry and electrical circuit details are not available. Each injection pulse is modeled as a sequence of up to four stages: an injection needle mechanical opening transient, a full-lift viscous flow inertial transient, a Bernoulli steady-state stage, and a needle descent transient. Parameters for each stage are obtained as polynomial fits from measured injection rate properties. The model enforces total injected mass, and the intermediate stages are only introduced if the injection pulse duration is long enough. Experimental rates of injection from two separate campaigns on the same injector were used to calibrate the model. The model was first validated against measured injection rate laws featuring pilot injections, short partially premixed combustion pulses, and conventional diesel combustion injection strategies. Then, it was employed as an input to engine computational fluid dynamics simulations, which were run to simulate experiments of mixture formation in an optically accessible light-duty diesel engine. It was found that, though simple, this model is capable of predicting both pilot and main injection pulse mass flow rates well: the simulations yielded accurate predictions of in-cylinder equivalence ratio distributions from injection strategies for both partially premixed combustion and pilot injections. Also, once calibrated, the model produced appropriate results for a wide range of injected mass and rail pressure values. Finally, it was observed that usage of such a relatively simple model can be a good choice when high-fidelity injection rate input and highly detailed information of the injector’s geometry and operation are not available, particularly as noticeable discrepancies can be present also among different experimental campaigns on similar hardware.

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Ferrari, Alessandro, et Pietro Pizzo. « Fully predictive Common Rail fuel injection apparatus model and its application to global system dynamics analyses ». International Journal of Engine Research 18, n^o 3 (28 juillet 2016) : 273–90. http://dx.doi.org/10.1177/1468087416653246.

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A fully predictive model of a Common Rail fuel injection apparatus, which includes a detailed simulation of rail, pump, piping system, injectors and rail pressure control system, is presented and discussed. The high-pressure pump and injector sub-models have been validated separately and then coupled to the rail and pressure control system sub-models. The complete predictive model has been validated and applied to investigate the effects of the dynamics of each component of the injection apparatus on the rail pressure time history. Variable timing of the high-pressure pump delivery phases has also been considered, and the influence of this parameter on the injection performance has been analysed for both single- and multiple-injection events. Furthermore, the injection system dynamics during the transients between steady-state working conditions has been investigated in order to highlight the role played by the dynamic response of the pressure control system on the rail pressure time history.

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Ge, Haiwen, Jaclyn E. Johnson, Hari Krishnamoorthy, Seong-Young Lee, Jeffrey D. Naber, Nan Robarge et Eric Kurtz. « A comparison of computational fluid dynamics predicted initial liquid penetration using rate of injection profiles generated using two different measurement techniques ». International Journal of Engine Research 20, n^o 2 (15 décembre 2017) : 226–35. http://dx.doi.org/10.1177/1468087417746475.

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The rate of injection profile is a key parameter describing the fuel injection process for diesel injection. It is also an essential input parameter for computational fluid dynamics simulations of spray flows. In the present work, rate of injection profiles of a multi-hole diesel injector were measured using the Zeuch method and the momentum flux method. The rate of injection profiles measured by the momentum flux method had a faster rise in rate of injection during the initial ramp-up phase than with the Zeuch method. The measured rate of injection profiles were applied in three-dimensional computational fluid dynamics simulations of diesel sprays under non-vaporizing and vaporizing conditions with sweeps in injection pressure, bulk charge gas density, and bulk charge gas temperature. Analytical results were compared against experimental data for liquid penetration generated under those conditions. Computational fluid dynamics results with the rate of injection profile measured by the Zeuch method under-predict liquid penetration during the initial ramp-up phase, while computational fluid dynamics results with the rate of injection profiles measured by the momentum flux method showed much better agreement with the experimental data of liquid length and penetration. This suggests that current computational fluid dynamics spray models may be able to more accurately model transient liquid penetration when using the velocity profile developed from momentum flux measurements. Further study is needed to evaluate how computational fluid dynamics predictions of combustion and emissions of affected when using these two rate of injection profiles.

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Aksamit, Nikolas O., Ben Kravitz, Douglas G. MacMartin et George Haller. « Harnessing stratospheric diffusion barriers for enhanced climate geoengineering ». Atmospheric Chemistry and Physics 21, n^o 11 (11 juin 2021) : 8845–61. http://dx.doi.org/10.5194/acp-21-8845-2021.

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Abstract. Stratospheric sulfate aerosol geoengineering is a proposed method to temporarily intervene in the climate system to increase the reflectance of shortwave radiation and reduce mean global temperature. In previous climate modeling studies, choosing injection locations for geoengineering aerosols has, thus far, only utilized the average dynamics of stratospheric wind fields instead of accounting for the essential role of time-varying material transport barriers in turbulent atmospheric flows. Here we conduct the first analysis of sulfate aerosol dispersion in the stratosphere, comparing what is now a standard fixed-injection scheme with time-varying injection locations that harness short-term stratospheric diffusion barriers. We show how diffusive transport barriers can quickly be identified, and we provide an automated injection location selection algorithm using short forecast and reanalysis data. Within the first 7 d days of transport, the dynamics-based approach is able to produce particle distributions with greater global coverage than fixed-site methods with fewer injections. Additionally, this enhanced dispersion slows aerosol microphysical growth and can reduce the effective radii of aerosols up to 200–300 d after injection. While the long-term dynamics of aerosol dispersion are accurately predicted with transport barriers calculated from short forecasts, the long-term influence on radiative forcing is more difficult to predict and warrants deeper investigation. Statistically significant changes in radiative forcing at timescales beyond the forecasting window showed mixed results, potentially increasing or decreasing forcing after 1 year when compared to fixed injections. We conclude that future feasibility studies of geoengineering should consider the cooling benefits possible by strategically injecting sulfate aerosols at optimized time-varying locations. Our method of utilizing time-varying attracting and repelling structures shows great promise for identifying optimal dispersion locations, and radiative forcing impacts can be improved by considering additional meteorological variables.

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Aghaie Meybodi, Mohamad, Rohit Saini, Amirfarhang Mehdizadeh et Reza Hejazi. « Computational Fluid Dynamics (CFD)-Based Optimization of Injection Process during Endoscopic Mucosal Therapy ». Bioengineering 7, n^o 4 (27 octobre 2020) : 136. http://dx.doi.org/10.3390/bioengineering7040136.

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Creation of a submucosal plane to separate the lesion from the deeper muscle layer in gastrointestinal tract is an integral and essential part of endoscopic resection therapies such as endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). Thereby, an optimized submucosal injection technique is required to ensure a successful process. In this study, the computational fluid dynamics (CFD) technique is employed as a foundational step towards the development of a framework that can provide useful directions to optimize the injection process. Three different lifting agents, including Glycerol, Eleview®, and ORISE® gel have been used for this study. The role of different injection angles, injection dynamics, and effect of temperature are studied to understand the lifting characteristic of each agent. The study shows that Eleview® provides the highest lifting effect, including the initial injection period. To evaluate the impact of the injection process, two cases are simulated, termed static injection and dynamic injection. Under static injection, the injection angle is investigated from lower to higher angles of injection. In the dynamic injection, two cases are modulated, where a continuous change of injection angle from lower to higher degrees (denoted as clockwise) and vice-versa in the anti-clockwise direction are investigated. Increased lifting characteristics are observed at decreasing/lower angle of injection. Further, the correlation between temperature of the lifting agents and their lifting characteristics is investigated.

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Shatrov, Mikhail, Leonid Golubkov, Andrey Dunin, Andrey Yakovenko et Pavel Dushkin. « Influence of high injection pressure on fuel injection perfomances and diesel engine worcking process ». Thermal Science 19, n^o 6 (2015) : 2245–53. http://dx.doi.org/10.2298/tsci151109192s.

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In MADI, investigations are carried out in the field of diesel engine working process perfection for complying with prospective ecological standards such as Euro-6 and Tier-4. The article describes the results of the first stage of experimental research of the influence of injection pressure up to 3000 bar on working processes of diesel engine and its fuel system. Justification of the design of a Common Rail injector for fuel injection under 3000 bar pressure is presented. The influence of raising injection pressure (up to 3000 bar) on the fuel spray propagation dynamics is demonstrated. The combined influence of injection pressure (up to 3000 bar) and air boost pressure on fuel spray propagation dynamics is shown, including on engine emission and noise.

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Bensalem, Chafik, Abdallah Benarous et Pierre-Olivier Logerais. « Numerical analysis of the flow dynamics of an N2 cryogenic jet ». Thermal Science, n^o 00 (2020) : 162. http://dx.doi.org/10.2298/tsci190805162b.

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Injection and mixing of cryogenic propellants are very complex at near-critical and supercritical conditions. The concise description and the reliable measurements on such flows are still questionable. In this work, a Reynolds Averaged Navier-Stokes (RANS) study is performed for a pure N2 fluid injection at transcritical conditions on a laboratory scale test rig. An indepth thermodynamical analysis on the real-gas behavior has allowed N2 density prediction over the experimental range of the injection temperature and for several equations of state (EoS). A focus was thrown on the prediction of the density evolution on the chamber centerline and across the injector. The calculations were performed using both adiabatic and constant temperature conditions for the injector wall. The inner heat transfer in the injector had a significant effect on the jet density distribution and therefore on the overall flow dynamics. Numerical results regarding axial profiles of density and dense core lengths agree fairly well with the experimental data provided by the literature.

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Gu, F., et A. D. Ball. « Diesel Injector Dynamic Modelling and Estimation of Injection Parameters from Impact Response Part 1 : Modelling and Analysis of Injector Impacts ». Proceedings of the Institution of Mechanical Engineers, Part D : Journal of Automobile Engineering 210, n^o 4 (octobre 1996) : 293–302. http://dx.doi.org/10.1243/pime_proc_1996_210_276_02.

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Part 1 of this paper presents the development and validation of a detailed dynamic model for the needle motion of a common hole-type dieselfuel injector as used in a direct injection diesel engine. The injector needle motion is described as a two-mass piece-wise linear vibro-impact system, unlike the conventional modelling techniques which use a single-mass approach. The use of two masses permits analysis of both the needle impact behaviour and of the more general dynamics of the fuel injection process. Model parameters are derived from a combination of measurement and estimation, and the subsequent model is evaluated via direct measurement of the spring seat displacement. The opening and closing needle impact behaviour is shown to exhibit close correlation with key injection parameters, including fuel injection pressure, fuelling rate and timing. The model revealed that the impact of the needle when opening is found to exhibit lower amplitude but more high-frequency components than the impact associated with the closing. The measurement of the injector body vibration response to these impacts is shown to enable non-intrusive estimation of injection parameters, alleviating the problems associated with conventional intrusive needle-lift measurement.

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YAN, YONG-HONG, CHANG-QIN WU et BAO-WEN LI. « BIPOLARON DYNAMICS IN NON-DEGENERATE POLYMERS ». International Journal of Modern Physics B 21, n^o 23n24 (30 septembre 2007) : 4190–95. http://dx.doi.org/10.1142/s0217979207045396.

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Bipolaron dynamics in non-degenerate polymers are discussed using the nonadiabatic dynamic method. First, charge injection process from metal electrode to a nondegenerate polymer in a metal/polymer/metal structure has been investigated. We demonstrate that the dynamical formation of a bipolaron sensitively depends on the work function of metal electrode. We also study the bipolaron dissociation process. It is found that the electric field that can dissociate the bipolaron is up to 106 V/cm, which is consistent with experiments.

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Doumbia, Yaya, Tushar Malica, Delphine Wolfersberger, Krassimir Panajotov et Marc Sciamanna. « Optical injection dynamics of frequency combs ». Optics Letters 45, n^o 2 (10 janvier 2020) : 435. http://dx.doi.org/10.1364/ol.381039.

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Rosenzweig, J. B. « Injection and dynamics of accelerated beams ». Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment 410, n^o 3 (juin 1998) : 335–39. http://dx.doi.org/10.1016/s0168-9002(98)00161-2.

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Yang, Renyou, Gerasimos Theotokatos et Dracos Vassalos. « Parametric investigation of a large two-stroke marine high-pressure direct injection engine by using computational fluid dynamics method ». Proceedings of the Institution of Mechanical Engineers, Part M : Journal of Engineering for the Maritime Environment 234, n^o 3 (21 janvier 2020) : 699–711. http://dx.doi.org/10.1177/1475090219895639.

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This study aims at the parametric investigation of the gas injection system settings of a large marine two-stroke dual fuel engine by using a developed and customized CFD method in the ANSYS Fluent software. The investigated engine injection system parameters include the gas injection timing, the gas injection duration, the gas injector lateral angle, and the gas injector holes number. Based on the comparison of the predicted performance parameters for the closed-cycle processes, the results indicate that the gas injector lateral angle is the most significant parameter that affects the engine power as well as the NO and CO2 emissions. For satisfying the contradictory objectives of retaining the engine power and reducing the NO and CO2 emissions, appropriate design settings for the gas injection are recommended for the investigated engine operation in the gas mode at 75% load.

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Gong, Huifeng, Weidi Huang, Ya Gao, Jin Wang, Akira Arioka et Yuzuru Sasaki. « End-of-injection fuel dribbling dynamics of multi-hole GDI injector ». Fuel 317 (juin 2022) : 123406. http://dx.doi.org/10.1016/j.fuel.2022.123406.

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Maghsoodi, Ameneh, Anupam Chatterjee, Ioan Andricioaei et Noel C. Perkins. « How the phage T4 injection machinery works including energetics, forces, and dynamic pathway ». Proceedings of the National Academy of Sciences 116, n^o 50 (25 novembre 2019) : 25097–105. http://dx.doi.org/10.1073/pnas.1909298116.

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The virus bacteriophage T4, from the family Myoviridae, employs an intriguing contractile injection machine to inject its genome into the bacterium Escherichia coli. Although the atomic structure of phage T4 is largely understood, the dynamics of its injection machinery remains unknown. This study contributes a system-level model describing the nonlinear dynamics of the phage T4 injection machinery interacting with a host cell. The model employs a continuum representation of the contractile sheath using elastic constants inferred from atomistic molecular-dynamics (MD) simulations. Importantly, the sheath model is coupled to component models representing the remaining structures of the virus and the host cell. The resulting system-level model captures virus–cell interactions as well as competing energetic mechanisms that release and dissipate energy during the injection process. Simulations reveal the dynamical pathway of the injection process as a “contraction wave” that propagates along the sheath, the energy that powers the injection machinery, the forces responsible for piercing the host cell membrane, and the energy dissipation that controls the timescale of the injection process. These results from the model compare favorably with the available (but limited) experimental measurements.

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Kamiński, Mariusz, Piotr Budzyński, Jacek Hunicz et Jerzy Józwik. « Evaluation of changes in fuel delivery rate by electromagnetic injectors in a common rail system during simulated operation ». Eksploatacja i Niezawodnosc - Maintenance and Reliability 23, n^o 2 (22 mars 2021) : 352–58. http://dx.doi.org/10.17531/ein.2021.2.15.

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The objective of this study was to determine changes in fuel delivery rate by common rail system injectors during their simulated operation on a test stand. Four Bosch injectors used, among others, in Fiat 1.3 Multijet engines were tested. The injectors were operated on a test rig at room temperature for 500 hours (more than 72 million work cycles). During the test, pressure and injection frequency were changed. Changes in the operating parameters were estimated based on obtained injection characteristics and effective flow area determined thereby. The observed changes in fuel delivery rate were compared with results of the surface analysis of control valves and nozzle needles. Despite the stated lack of wear, significant changes in the dynamics of injector operation were observed, particularly at short injection times. Small pilot injections do not have to be corrected by the fuel injection control system because they do not affect the changes in torque; however, they do affect the combustion process. This creates conditions for increased emission of toxic exhaust components.

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Wang, Tianbo, Lanchun Zhang et Qian Chen. « Effect of Valve Opening Manner and Sealing Method on the Steady Injection Characteristic of Gas Fuel Injector ». Energies 13, n^o 6 (20 mars 2020) : 1479. http://dx.doi.org/10.3390/en13061479.

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The steady-state injection characteristic of gas fuel injector is one of the key factors that affects the performance of gas fuel engine. The influences of different injection strategies, such as different injection angles and different injection positions, on the mixing performance in gas-fueled engine have been emphasized in previous literatures. However, the research on the injection characteristics of the gas fuel injector itself are insufficient. The three-dimensional steady-state computational fluid dynamics (CFD) models of two kinds of injectors, in different opening manners, and the other two kinds of injectors, in different sealing methods, were established in this paper. The core region speed, stagnation pressure loss and mass flow rate were compared. Additionally, the effective injection pressure (EIP) concept was also used to evaluate the injection efficiency of gas fuel injector. The simulation results show that the jet speed of the pull-open injector is higher than the push-open injector under the same operating conditions. The injection efficiency of the pull-open valve is about 56.0%, while the push-open valve is 50.3%. In general, the steady-flow characteristic of the pull-open injector is better than that of the push-open one. The injection efficiency of the flat sealing injector is 55.2%, slightly lower than the conical sealing method.

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Shin, Hyun-Ho, et Woong-Sup Yoon. « Non-Equilibrium Molecular Dynamics Simulation of Nanojet Injection with Adaptive-Spatial Decomposition Parallel Algorithm ». Journal of Nanoscience and Nanotechnology 8, n^o 7 (1 juillet 2008) : 3661–73. http://dx.doi.org/10.1166/jnn.2008.18332.

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An Adaptive-Spatial Decomposition parallel algorithm was developed to increase computation efficiency for molecular dynamics simulations of nano-fluids. Injection of a liquid argon jet with a scale of 17.6 molecular diameters was investigated. A solid annular platinum injector was also solved simultaneously with the liquid injectant by adopting a solid modeling technique which incorporates phantom atoms. The viscous heat was naturally discharged through the solids so the liquid boiling problem was avoided with no separate use of temperature controlling methods. Parametric investigations of injection speed, wall temperature, and injector length were made. A sudden pressure drop at the orifice exit causes flash boiling of the liquid departing the nozzle exit with strong evaporation on the surface of the liquids, while rendering a slender jet. The elevation of the injection speed and the wall temperature causes an activation of the surface evaporation concurrent with reduction in the jet breakup length and the drop size.

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Katz, Gil, Mark A. Ratner et Ronnie Kosloff. « Hot Injection Dynamics : Design Mechanisms and Ideas ». Journal of Physical Chemistry A 115, n^o 23 (16 juin 2011) : 5833–37. http://dx.doi.org/10.1021/jp109706h.

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Lewis, Frederick D., Xiaoyang Liu, Scott E. Miller, Ryan T. Hayes et Michael R. Wasielewski. « Dynamics of Electron Injection in DNA Hairpins ». Journal of the American Chemical Society 124, n^o 38 (septembre 2002) : 11280–81. http://dx.doi.org/10.1021/ja026751d.

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Golombok, Michael, et D. Barry Pye. « Droplet dynamics in a diesel injection spray ». Fuel 69, n^o 9 (septembre 1990) : 1200–1202. http://dx.doi.org/10.1016/0016-2361(90)90081-z.

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Terpinskaya, T. I. « Dynamics of Antitumor Resistance after Cyclophosphamide Injection ». Bulletin of Experimental Biology and Medicine 152, n^o 5 (mars 2012) : 613–14. http://dx.doi.org/10.1007/s10517-012-1589-8.

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Jiang, Zai-Fu, Zheng-Mao Wu, Elumalai Jayaprasath, Wen-Yan Yang, Chun-Xia Hu et Guang-Qiong Xia. « Nonlinear Dynamics of Exclusive Excited-State Emission Quantum Dot Lasers Under Optical Injection ». Photonics 6, n^o 2 (27 mai 2019) : 58. http://dx.doi.org/10.3390/photonics6020058.

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We numerically investigate the nonlinear dynamic properties of an exclusive excited-state (ES) emission quantum dot (QD) laser under optical injection. The results show that, under suitable injection parameters, the ES-QD laser can exhibit rich nonlinear dynamical behaviors, such as injection locking (IL), period one (P1), period two (P2), multi-period (MP), and chaotic pulsation (CP). Through mapping these dynamic states in the parameter space of the frequency detuning and the injection coefficient, it can be found that the IL occupies a wide region and the dynamic evolution routes appear in multiple forms. Via permutation entropy (PE) calculation to quantify the complexity of the CP state, the parameter range for acquiring the chaos with high complexity can be determined. Moreover, the influence of the linewidth enhancement factor (LEF) on the dynamical state of the ES-QD laser is analyzed. With the increase of the LEF value, the chaotic area shrinks (expands) in the negative (positive) frequency detuning region, and the IL region gradually shifts towards the negative frequency detuning.

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Weisenstein, Debra K., Daniele Visioni, Henning Franke, Ulrike Niemeier, Sandro Vattioni, Gabriel Chiodo, Thomas Peter et David W. Keith. « An interactive stratospheric aerosol model intercomparison of solar geoengineering by stratospheric injection of SO2</sub&gt ; or accumulation-mode sulfuric acid aerosols ». Atmospheric Chemistry and Physics 22, n^o 5 (4 mars 2022) : 2955–73. http://dx.doi.org/10.5194/acp-22-2955-2022.

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Abstract. Studies of stratospheric solar geoengineering have tended to focus on modification of the sulfuric acid aerosol layer, and almost all climate model experiments that mechanistically increase the sulfuric acid aerosol burden assume injection of SO2. A key finding from these model studies is that the radiative forcing would increase sublinearly with increasing SO2 injection because most of the added sulfur increases the mass of existing particles, resulting in shorter aerosol residence times and aerosols that are above the optimal size for scattering. Injection of SO3 or H2SO4 from an aircraft in stratospheric flight is expected to produce particles predominantly in the accumulation-mode size range following microphysical processing within an expanding plume, and such injection may result in a smaller average stratospheric particle size, allowing a given injection of sulfur to produce more radiative forcing. We report the first multi-model intercomparison to evaluate this approach, which we label AM-H2SO4 injection. A coordinated multi-model experiment designed to represent this SO3- or H2SO4-driven geoengineering scenario was carried out with three interactive stratospheric aerosol microphysics models: the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM2) with the Whole Atmosphere Community Climate Model (WACCM) atmospheric configuration, the Max-Planck Institute's middle atmosphere version of ECHAM5 with the HAM microphysical module (MAECHAM5-HAM) and ETH's SOlar Climate Ozone Links with AER microphysics (SOCOL-AER) coordinated as a test-bed experiment within the Geoengineering Model Intercomparison Project (GeoMIP). The intercomparison explores how the injection of new accumulation-mode particles changes the large-scale particle size distribution and thus the overall radiative and dynamical response to stratospheric sulfur injection. Each model used the same injection scenarios testing AM-H2SO4 and SO2 injections at 5 and 25 Tg(S) yr−1 to test linearity and climate response sensitivity. All three models find that AM-H2SO4 injection increases the radiative efficacy, defined as the radiative forcing per unit of sulfur injected, relative to SO2 injection. Increased radiative efficacy means that when compared to the use of SO2 to produce the same radiative forcing, AM-H2SO4 emissions would reduce side effects of sulfuric acid aerosol geoengineering that are proportional to mass burden. The model studies were carried out with two different idealized geographical distributions of injection mass representing deployment scenarios with different objectives, one designed to force mainly the midlatitudes by injecting into two grid points at 30∘ N and 30∘ S, and the other designed to maximize aerosol residence time by injecting uniformly in the region between 30∘ S and 30∘ N. Analysis of aerosol size distributions in the perturbed stratosphere of the models shows that particle sizes evolve differently in response to concentrated versus dispersed injections depending on the form of the injected sulfur (SO2 gas or AM-H2SO4 particulate) and suggests that prior model results for concentrated injection of SO2 may be strongly dependent on model resolution. Differences among models arise from differences in aerosol formulation and differences in model dynamics, factors whose interplay cannot be easily untangled by this intercomparison.

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Lorke, Michael, Igor Khanonkin, Stephan Michael, Johann Peter Reithmaier, Gadi Eisenstein et Frank Jahnke. « Carrier dynamics in quantum-dot tunnel-injection structures : Microscopic theory and experiment ». Applied Physics Letters 121, n^o 10 (5 septembre 2022) : 103503. http://dx.doi.org/10.1063/5.0101613.

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Tunneling-injection structures are incorporated in semiconductor lasers in order to overcome the fundamental dynamical limitation due to hot carrier injection by providing a carrier transport path from a cold carrier reservoir. The tunneling process itself depends on band alignment between quantum-dot levels and the injector quantum well, especially as in these devices LO-phonon scattering is dominant. Quantum dots with their first excited state near the quantum well bottom profit the most from tunnel coupling. As inhomogeneous broadening is omnipresent in quantum dot structures, this implies that individual members of the ensemble couple differently to the injector quantum well. Quantum dots with higher energy profit less, as the phonon couples to higher, less occupied states. Likewise, if the energy difference between ground state and quantum well exceeds the LO-phonon energy, scattering becomes increasingly inefficient. Therefore, within 20–30 meV, we find quantum dots that benefit substantially different from the tunnel coupling. Furthermore, in quantum dots with increasing confinement depth, excited states become successively confined. Here, scattering gets more efficient again, as subsequent excited states reach the phonon resonance with the quantum well bottom. Our results provide guidelines for the optimization of tunnel-injection lasers. Theoretical results for electronic state calculations in connection with carrier–phonon and carrier–carrier scattering are compared to the experimental results of the temporal gain recovery after a short pulse perturbation.

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Niemeier, Ulrike, Jadwiga H. Richter et Simone Tilmes. « Differing responses of the quasi-biennial oscillation to artificial SO2 ; injections in two global models ». Atmospheric Chemistry and Physics 20, n^o 14 (29 juillet 2020) : 8975–87. http://dx.doi.org/10.5194/acp-20-8975-2020.

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Abstract. Artificial injections of sulfur dioxide (SO2) into the stratosphere show in several model studies an impact on stratospheric dynamics. The quasi-biennial oscillation (QBO) has been shown to slow down or even vanish under higher SO2 injections in the equatorial region. But the impact is only qualitatively but not quantitatively consistent across the different studies using different numerical models. The aim of this study is to understand the reasons behind the differences in the QBO response to SO2 injections between two general circulation models, the Whole Atmosphere Community Climate Model (WACCM-110L) and MAECHAM5-HAM. We show that the response of the QBO to injections with the same SO2 injection rate is very different in the two models, but similar when a similar stratospheric heating rate is induced by SO2 injections of different amounts. The reason for the different response of the QBO corresponding to the same injection rate is very different vertical advection in the two models, even in the control simulation. The stronger vertical advection in WACCM results in a higher aerosol burden and stronger heating of the aerosols and, consequently, in a vanishing QBO at lower injection rate than in simulations with MAECHAM5-HAM. The vertical velocity increases slightly in MAECHAM5-HAM when increasing the horizontal resolution. This study highlights the crucial role of dynamical processes and helps to understand the large uncertainties in the response of different models to artificial SO2 injections in climate engineering studies.

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Semak, G. R. « Clinical study of the efficacy of low molecular weight sodium hyaluronate in complex treatment of corneal graft disease ». Proceedings of the National Academy of Sciences of Belarus, Medical series 17, n^o 2 (6 juin 2020) : 170–77. http://dx.doi.org/10.29235/1814-6023-2020-17-2-170-177.

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The results of corneal graft disease treatment using low molecular weight sodium hyaluronate are presented.The study included 19 patients (20 eyes) aged 24 to 87 years, who developed graft disease after keratoplasty because of chronic dystrophic corneal diseases. The severity of symptoms during treatment was evaluated weekly during the course of therapy using the OSDI (Ocular Surface Disease Index). To assess the dynamics of objective signs of Dry eye disease in dynamics, visometry, biomicroscopy, Schirmer’s test and LIPCOF test were performed weekly before the next injection. A follow-up study was carried out a week after the last injection, with a 1-year dynamic observation following the treatment.Changes in objective indicators of the anterior eye surface were characterized by positive dynamics during therapy. The Schirmer test (p < 0.00001) increased most rapidly and significantly with a lasting effect for a month, demonstrating a beneficial therapeutic effect on both the aqueous and mucinous layer of the tear film. A decrease in the OSDI index was noted after the first injection and decreased progressively during the course of treatment and after its completion up to one month after the last injection (p < 0.00001).

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KAR, SANDIP, et DEB SHANKAR RAY. « NONLINEAR DYNAMICS OF GLYCOLYSIS ». Modern Physics Letters B 18, n^o 14 (10 juin 2004) : 653–78. http://dx.doi.org/10.1142/s0217984904007207.

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Glycolysis is the most important cellular process yielding ATP, the universal energy carrier molecule in all living organisms. The characteristic oscillations of the intermediates of glycolysis have been the subject of extensive experimental and theoretical research over the last four decades. A conspicuous property of the glycolytic oscillations is their critical control by the substrate injection rate. In this brief review, we trace its experimental background and explore the essential underlying theoretical models to elucidate a number of nonlinear dynamical phenomena observed in the weak noise limit of the substrate injection rate. Simultaneous oscillations of glycolytic intermediates and insulin have also been discussed within the framework of a phenomenological model in the context of basic experimental issues.

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Sizova, Elena, Sergey Miroshnikov, Elena Yausheva et Valentina Polyakova. « Assessment of Morphological and Functional Changes in Organs of Rats after Intramuscular Introduction of Iron Nanoparticles and Their Agglomerates ». BioMed Research International 2015 (2015) : 1–7. http://dx.doi.org/10.1155/2015/243173.

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The research was performed on male Wistar rats based on assumptions that new microelement preparations containing metal nanoparticles and their agglomerates had potential. Morphological and functional changes in tissues in the injection site and dynamics of chemical element metabolism (25 indicators) in body were assessed after repeated intramuscular injections (total, 7) with preparation containing agglomerate of iron nanoparticles. As a result, iron depot was formed in myosymplasts of injection sites. The quantity of muscle fibers having positive Perls’ stain increased with increasing number of injections. However, the concentration of the most chemical elements and iron significantly decreased in the whole skeletal muscle system (injection sites are not included). Consequently, it increased up to the control level after the sixth and the seventh injections. Among the studied organs (liver, kidneys, and spleen), Caspase-3 expression was revealed only in spleen. The expression had a direct dependence on the number of injections. Processes of iron elimination from preparation containing nanoparticles and their agglomerates had different intensity.

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Raut, Ankit A., et J. M. Mallikarjuna. « Effects of direct water injection and injector configurations on performance and emission characteristics of a gasoline direct injection engine : A computational fluid dynamics analysis ». International Journal of Engine Research 21, n^o 8 (2 décembre 2019) : 1520–40. http://dx.doi.org/10.1177/1468087419890418.

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In-cylinder water injection is a promising approach for reducing NOx and soot emissions from internal combustion engines. It allows one to use a higher compression ratio by reducing engine knock; hence, higher fuel economy and power output can be achieved. However, water injection can also affect engine combustion and emission characteristics if water injection and injector parameters are not properly set. Majority of the previous studies on the water injection are done through experiments. Therefore, subtle aspects of water injection such as in-cylinder interaction of water sprays, spatial distribution of water vapor, and effect on flame propagation are not clearly understood and rarely reported in literature due to experimental limitations. Thus, in the present article, a computational fluid dynamics investigation is carried out to analyze the effects of direct water injection under various injector configurations on water evaporation, combustion, performance, and emission characteristics of a gasoline direct injection engine. The emphasis is given to analyze in-cylinder water spray interactions, flame propagation, water spray droplet size distribution, and water vapor spatial distribution inside the engine cylinder. For the study, the water-to-fuel ratio is varied from 0 to 1. Various water injector configurations using nozzle hole diameters of 0.14, 0.179, and 0.205 mm, along with nozzle holes of 4, 5, 6, and 7, are considered for comparison in addition to the case of no_water. Computational fluid dynamics models used in this study are validated with the available data in literature. From the results, it is found that the emission and performance characteristics of the engine are highly dependent on water evaporation characteristics. Also, the water-to-fuel ratio of 0.6 with 6 number of nozzle holes and the nozzle diameter of 0.14 mm results in the highest indicated mean effective pressure and the lowest NOx, soot, and CO emissions compared to other cases considered.

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Engler, C., et W. Lorenz. « Electronic Charge Density Injection in Semiconductor Interfacial Processes : Quantumchemical Proof of Injection Dynamics ». Zeitschrift für Physikalische Chemie 205, Part_1 (janvier 1998) : 15–32. http://dx.doi.org/10.1524/zpch.1998.205.part_1.015.

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Deng, Chuanhai, Han Wang, Jieping Xiao et Yuqi Liu. « Influence of Charge Injection on Dynamic Characteristics of Space Charge in Polymer Thin Films Under AC Stress ». Journal of Physics : Conference Series 2224, n^o 1 (1 avril 2022) : 012050. http://dx.doi.org/10.1088/1742-6596/2224/1/012050.

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Abstract At present, most studies focused on the formation and accumulation of space charge under DC stress, relatively few studies focused on dynamic characteristics of space charge under AC stress. However, space charge dynamics under AC stress is of significance because the majorities of polymer insulation systems are subjected to AC voltage. In order to study the effect of charge injection mechanism from the electrodes on dynamic characteristics of space charge under AC stress, bipolar charge transport model are used to simulate the current density, electroluminescence intensity, space charge densities in polyethylene with different charge injection mechanisms. It is found that the simulated electroluminescence intensity and space charge densities under AC stress assuming the exponential functional approximation injection is more reasonable than those assuming the Schottky injection.

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Rahimi Boldaji, Mozhgan, Aimilios Sofianopoulos, Sotirios Mamalis et Benjamin Lawler. « Computational fluid dynamics investigations of the effect of water injection timing on thermal stratification and heat release in thermally stratified compression ignition combustion ». International Journal of Engine Research 20, n^o 5 (30 avril 2018) : 555–69. http://dx.doi.org/10.1177/1468087418767451.

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Advanced combustion concepts, like homogeneous charge compression ignition, are limited by their narrow operating range, which stems from a lack of control over the heat release process. This study explores a new advanced combustion mode, called thermally stratified compression ignition, which uses a direct water injection event to control the heat release process in low-temperature combustion. A three-dimensional computational fluid dynamics model coupled with detailed chemical kinetics is used to better understand the effects of direct water injection on thermal stratification in the cylinder and the resulting heat release process. Previous results showed that increasing the injection pressure results in a significantly broader temperature distribution due to increased evaporative cooling. In this way, direct water injection can control low-temperature combustion heat release and extend significantly the operable load range. In this study, simulations were performed over a range of start of injection timings in order to determine its effect on thermal stratification and heat release. The results show that for both low and high injection pressures advancing the start of water injection results in increased thermal stratification and reduced peak pressure and heat release rate for injections occurring after −60 °CAD. Before −60 °CAD, advancing the water injection has a varied effect on thermal stratification and heat release depending on the injection pressure and mass of the injected water.

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Doumbia, Yaya, Delphine Wolfersberger, Krassimir Panajotov et Marc Sciamanna. « Two Polarization Comb Dynamics in VCSELs Subject to Optical Injection ». Photonics 9, n^o 2 (18 février 2022) : 115. http://dx.doi.org/10.3390/photonics9020115.

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Optical frequency comb technologies have received intense attention due to their numerous promising applications ranging from optical communications to optical comb spectroscopy. In this study, we experimentally demonstrate a new approach of broadband comb generation based on the polarization mode competition in single-mode VCSELs. More specifically, we analyze nonlinear dynamics and polarization properties in VCSELs when subject of optical injection from a frequency comb. When varying injection parameters (injection strength and detuning frequency) and comb properties (comb spacing), we unveil several bifurcation sequences enabling the excitation of free-running depressed polarization mode. Interestingly, for some injection parameters, the polarization mode competition induces a single or a two polarization comb with controllable properties (repetition rate and power per line). We also show that the performance of the two polarization combs depends crucially on the injection current and on the injected comb spacing. We explain our experimental findings by utilizing the spin-flip VCSEL model (SFM) supplemented with terms for parallel optical injection of frequency comb. We provide a comparison between parallel and orthogonal optical injection in the VCSEL when varying injection parameters and SFM parameters. We show that orthogonal comb dynamics can be observed in a wide range of parameters, as for example dichroism linear dichroism (γa=−0.1 ns−1 to γa=−0.8 ns−1), injection current (μ=2.29 to μ=5.29) and spin-flip relaxation rate (γs=50 ns−1 to γs=2300 ns−1).

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Catania, A. E., C. Dongiovanni, A. Mittica, M. Badami et F. Lovisolo. « Numerical Analysis Versus Experimental Investigation of a Distributor-Type Diesel Fuel-Injection System ». Journal of Engineering for Gas Turbines and Power 116, n^o 4 (1 octobre 1994) : 814–30. http://dx.doi.org/10.1115/1.2906890.

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A production distributor-type fuel-injection system for diesel engines has been extensively investigated via computer-assisted simulation and experimentation. The investigation was mainly aimed at assessing and validating a sophisticated computational model of the system, developed with specific attention given to the pump and to some important aspects concerning the injection pressure simulation, such as the dynamic effects of the injector needle lift, the flow unsteadiness, and compressibility effects on the nozzle-hole discharge coefficient. The pump delivery assembly was provided with a valve of the reflux type. This presented a flat in the collar, forming a return-flow restriction with the seat, and had no retraction piston. A single-spring injector, with a reduced sac volume, was fitted to the system. The numerical analysis of transient flow phenomena linked to the mechanical unit dynamics, including possible cavitation occurrence in the system, was performed using an implicit finite-difference algorithm, previously set up for in-line injection equipment. Particular care was exercised in modeling the distributor pump so as to match the dynamics of the delivery-valve assembly to the pressure wave propagation in the distributor and its outlets. The so-called minor losses were also taken into account and it was ascertained that sudden expansion and contraction losses were significant for the type of pump examined. The experimental investigation was performed on a test bench at practical pump speeds. Pressures were measured in the pumping chamber, at two different pipe locations, and upstream to the needle seat opening passage. This last measurement was taken in order to evaluate the nozzle-hole flow coefficient with the support of the simulation, using experimental values of the needle lift, injection rate, and injected fuel quantity as known variables. The numerical and experimental results were compared and discussed, showing the validity of the model. The injection pressure time history and the influence of the delivery return-flow restriction on the system performance were numerically examined.

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Kleinschmitt, Christoph, Olivier Boucher et Ulrich Platt. « Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO2injection studied with the LMDZ-S3A model ». Atmospheric Chemistry and Physics 18, n^o 4 (27 février 2018) : 2769–86. http://dx.doi.org/10.5194/acp-18-2769-2018.

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Abstract. The enhancement of the stratospheric sulfate aerosol layer has been proposed as a method of geoengineering to abate global warming. Previous modelling studies found that stratospheric aerosol geoengineering (SAG) could effectively compensate for the warming by greenhouse gases on the global scale, but also that the achievable cooling effect per sulfur mass unit, i.e. the forcing efficiency, decreases with increasing injection rate. In this study we use the atmospheric general circulation model LMDZ with the sectional aerosol module S3A to determine how the forcing efficiency depends on the injected amount of SO2, the injection height, and the spatio-temporal pattern of injection. We find that the forcing efficiency may decrease more drastically for larger SO2 injections than previously estimated. As a result, the net instantaneous radiative forcing does not exceed the limit of –2 W m−2 for continuous equatorial SO2 injections and it decreases (in absolute value) for injection rates larger than 20 Tg S yr−1. In contrast to other studies, the net radiative forcing in our experiments is fairly constant with injection height (in a range 17 to 23 km) for a given amount of SO2 injected. Also, spreading the SO2 injections between 30∘ S and 30∘ N or injecting only seasonally from varying latitudes does not result in a significantly larger (i.e. more negative) radiative forcing. Other key characteristics of our simulations include a consequent stratospheric heating, caused by the absorption of solar and infrared radiation by the aerosol, and changes in stratospheric dynamics, with a collapse of the quasi-biennial oscillation at larger injection rates, which has impacts on the resulting spatial aerosol distribution, size, and optical properties. But it has to be noted that the complexity and uncertainty of stratospheric processes cause considerable disagreement among different modelling studies of stratospheric aerosol geoengineering. This may be addressed through detailed model intercomparison activities, as observations to constrain the simulations of stratospheric aerosol geoengineering are not available and analogues (such as volcanic eruptions) are imperfect.

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Sedlář, O., J. Balík, J. Černý, L. Peklová et K. Kubešová. « Dynamics of the nitrogen uptake by spring barley at injection application of nitrogen fertilizers ; ». Plant, Soil and Environment 59, No. 9 (5 septembre 2013) : 392–97. http://dx.doi.org/10.17221/76/2013-pse.

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Influence of CULTAN system (controlled uptake long term ammonium nutrition) on the nitrogen uptake by spring barley (Hordeum vulgare L.) was observed at 5-year small-plot field experiments under conditions of the Czech Republic (central Europe). Nitrogen uptake by CULTAN-fertilized plants was more even during vegetation period probably due to delayed term of fertilizer application. Nitrogen concentration in the aboveground biomass at BBCH 51 and in straw had no effect on grain yield. Post-heading nitrogen uptake as well as contribution of nitrogen translocation to total nitrogen in grain did not differ among both nitrogen fertilization treatments. Increase in grain size of spring barley by the CULTAN system can be explained by tendency to lower number of ears per area rather than by prolonged nitrogen uptake from soil. Lower protein content in grain of CULTAN-fertilized spring barley can be caused by increase in grain retained on a 2.5 mm sieve and also decrease in total nitrogen concentration in above-ground biomass at BBCH 51. No significant effect of CULTAN treatment on nitrogen use efficiency and nitrogen uptake efficiency was recorded. Significantly higher nitrogen utilization efficiency at CULTAN treatment could be explained by lower grain protein content compared to conventional treatment.

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Ismailov, M., Tsuneaki Ishima, T. Obokata, M. Tsukagoshi et K. Kobayashi. « Control of Transient Injection and Fast Spray Dynamics ». International Journal of Fluid Mechanics Research 24, n^o 1-3 (1997) : 294–306. http://dx.doi.org/10.1615/interjfluidmechres.v24.i1-3.290.

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Gready, David, et Gadi Eisenstein. « Carrier Dynamics in Tunneling Injection Quantum Dot Lasers ». IEEE Journal of Quantum Electronics 46, n^o 11 (novembre 2010) : 1611–18. http://dx.doi.org/10.1109/jqe.2010.2055043.

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Génin, Franklin, et Suresh Menon. « Dynamics of sonic jet injection into supersonic crossflow ». Journal of Turbulence 11 (janvier 2010) : N4. http://dx.doi.org/10.1080/14685240903217813.

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Jarrahbashi, D., et W. A. Sirignano. « Vorticity dynamics for transient high-pressure liquid injection ». Physics of Fluids 26, n^o 10 (octobre 2014) : 101304. http://dx.doi.org/10.1063/1.4895781.

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Milot, Rebecca L., et Charles A. Schmuttenmaer. « Electron Injection Dynamics in High-Potential Porphyrin Photoanodes ». Accounts of Chemical Research 48, n^o 5 (4 mai 2015) : 1423–31. http://dx.doi.org/10.1021/ar500363q.

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Frankel, Michael Y., Gregory L. Belenky, Serge Luryi, Thomas F. Carruthers, Michael L. Dennis, Alfred Y. Cho, R. A. Hamm et Deborah L. Sivco. « Carrier dynamics and photodetection in charge injection transistors ». Journal of Applied Physics 79, n^o 6 (15 mars 1996) : 3312–17. http://dx.doi.org/10.1063/1.361231.

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Morozov, V. N. « Theory of the dynamics of semiconductor injection lasers ». Journal of the Optical Society of America B 5, n^o 5 (1 mai 1988) : 909. http://dx.doi.org/10.1364/josab.5.000909.

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Zhu, Li-Ping, Yu Qiu et Guo-Ping Tong. « Nonadiabatic dynamics of electron injection into organic molecules ». Chinese Physics B 21, n^o 7 (juillet 2012) : 077302. http://dx.doi.org/10.1088/1674-1056/21/7/077302.

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Yang, X. F., Z. P. Xie, G. W. Liu et Y. Huang. « Dynamics of water debinding in ceramic injection moulding ». Advances in Applied Ceramics 108, n^o 5 (juillet 2009) : 295–300. http://dx.doi.org/10.1179/174367608x362430.

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Gelens, Lendert, Stefano Beri, Guy Van der Sande, Jan Danckaert, Nicola Calabretta, Harm J. S. Dorren, Richard Nötzel, Erwin A. J. M. Bente et Meint K. Smit. « Optical injection in semiconductor ring lasers : backfire dynamics ». Optics Express 16, n^o 15 (8 juillet 2008) : 10968. http://dx.doi.org/10.1364/oe.16.010968.

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Maghsoodi, Ameneh, Anupam Chatterjee, Ioan Andricioaei et Noel C. Perkins. « Dynamics and Energetics of Phage T4 Injection Machinery ». Biophysical Journal 112, n^o 3 (février 2017) : 153a. http://dx.doi.org/10.1016/j.bpj.2016.11.838.

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Grancini, Giulia, Daniele Viola, Yonghui Lee, Michael Saliba, Sanghyun Paek, Kyung Taek Cho, Simonetta Orlandi et al. « Femtosecond Charge-Injection Dynamics at Hybrid Perovskite Interfaces ». ChemPhysChem 18, n^o 17 (19 juillet 2017) : 2381–89. http://dx.doi.org/10.1002/cphc.201700492.

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Serrano, José Ramón, Pedro Piqueras, Joaquín de la Morena et Enrique José Sanchis. « Late Fuel Post-Injection Influence on the Dynamics and Efficiency of Wall-Flow Particulate Filters Regeneration ». Applied Sciences 9, n^o 24 (9 décembre 2019) : 5384. http://dx.doi.org/10.3390/app9245384.

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Late fuel post-injections are the most usual strategy to reach high exhaust temperature for the active regeneration of diesel particulate filters. However, it is important to optimise these strategies in order to mitigate their negative effect on the engine fuel consumption. This work aims at understanding the influence of the post-injection parameters, such as its start of injection and its fuel quantity, on the duration of the regeneration event and the fuel consumption along it. For this purpose, a set of computational models are employed to figure out in a holistic way the involved phenomena in the interaction between the engine and the exhaust gas aftertreatment system. Firstly, an engine model is implemented to evaluate the effect of the late fuel post-injection pattern on the gas properties at the exhaust aftertreatment system inlet in different steady-state operating conditions. These are selected to provide representative boundary conditions of the exhaust gas flow concerning dwell time, exhaust temperature and O 2 concentration. In this way, the results are later applied to the analysis of the diesel oxidation catalyst and wall-flow particulate filter responses. The dependence of the diesel particulate filter (DPF) inlet temperature is discussed based on the efficiency of each post-injection strategy to increase the exhaust gas temperature. Next, the influence on the dynamics of the regeneration of the post-injection parameters through the change in gas temperature and O 2 concentration is finally studied distinguishing the pre-heating, maximum reactivity and late soot oxidation stages as well as the required fuel consumption to complete the regeneration process.

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