Готові списки джерел за темами / Injection dynamics

Добірка наукової літератури з теми "Injection dynamics"

Автор: Grafiati
Опубліковано: 14 березня 2023

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями

Оберіть тип джерела:

Зміст

Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Injection dynamics".

Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.

Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.

Статті в журналах з теми "Injection dynamics"

1

Yao, Xigui, Zhendong Zhang, Xiangdong Kong, and Congbo Yin. "Dynamic Response Analysis and Structure Optimization of GDI Injector based on Mathematical Model." International Journal of Reliability, Quality and Safety Engineering 25, no. 02 (March 6, 2018): 1850008. http://dx.doi.org/10.1142/s0218539318500080.

Повний текст джерела
Анотація:
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.
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Perini, Federico, Stephen Busch, and 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, no. 7 (January 31, 2020): 1826–39. http://dx.doi.org/10.1177/0954407019898062.

Повний текст джерела
Анотація:
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.
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Ferrari, Alessandro, and Pietro Pizzo. "Fully predictive Common Rail fuel injection apparatus model and its application to global system dynamics analyses." International Journal of Engine Research 18, no. 3 (July 28, 2016): 273–90. http://dx.doi.org/10.1177/1468087416653246.

Повний текст джерела
Анотація:
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.
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Ge, Haiwen, Jaclyn E. Johnson, Hari Krishnamoorthy, Seong-Young Lee, Jeffrey D. Naber, Nan Robarge, and 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, no. 2 (December 15, 2017): 226–35. http://dx.doi.org/10.1177/1468087417746475.

Повний текст джерела
Анотація:
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.
Стилі APA, Harvard, Vancouver, ISO та ін.
5

Aksamit, Nikolas O., Ben Kravitz, Douglas G. MacMartin, and George Haller. "Harnessing stratospheric diffusion barriers for enhanced climate geoengineering." Atmospheric Chemistry and Physics 21, no. 11 (June 11, 2021): 8845–61. http://dx.doi.org/10.5194/acp-21-8845-2021.

Повний текст джерела
Анотація:
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.
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Aghaie Meybodi, Mohamad, Rohit Saini, Amirfarhang Mehdizadeh, and Reza Hejazi. "Computational Fluid Dynamics (CFD)-Based Optimization of Injection Process during Endoscopic Mucosal Therapy." Bioengineering 7, no. 4 (October 27, 2020): 136. http://dx.doi.org/10.3390/bioengineering7040136.

Повний текст джерела
Анотація:
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.
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Shatrov, Mikhail, Leonid Golubkov, Andrey Dunin, Andrey Yakovenko, and Pavel Dushkin. "Influence of high injection pressure on fuel injection perfomances and diesel engine worcking process." Thermal Science 19, no. 6 (2015): 2245–53. http://dx.doi.org/10.2298/tsci151109192s.

Повний текст джерела
Анотація:
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.
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Bensalem, Chafik, Abdallah Benarous, and Pierre-Olivier Logerais. "Numerical analysis of the flow dynamics of an N2 cryogenic jet." Thermal Science, no. 00 (2020): 162. http://dx.doi.org/10.2298/tsci190805162b.

Повний текст джерела
Анотація:
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.
Стилі APA, Harvard, Vancouver, ISO та ін.
9

Gu, F., and 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, no. 4 (October 1996): 293–302. http://dx.doi.org/10.1243/pime_proc_1996_210_276_02.

Повний текст джерела
Анотація:
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.
Стилі APA, Harvard, Vancouver, ISO та ін.
10

YAN, YONG-HONG, CHANG-QIN WU, and BAO-WEN LI. "BIPOLARON DYNAMICS IN NON-DEGENERATE POLYMERS." International Journal of Modern Physics B 21, no. 23n24 (September 30, 2007): 4190–95. http://dx.doi.org/10.1142/s0217979207045396.

Повний текст джерела
Анотація:
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.
Стилі APA, Harvard, Vancouver, ISO та ін.
Більше джерел

Дисертації з теми "Injection dynamics"

1

Conley, Nancy Ann. "The dynamics of cavity pressure in thermoplastic injection molding /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65924.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Hudgins, Duane Edward. "Suppression of premixed combustion dynamics utilizing microjet air injection." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45213.

Повний текст джерела
Анотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.
Includes bibliographical references (leaves 119-123).
The problem of thermoacoustic instability in continuous combustion systems is a major challenge in the field of propulsion and power generation. With the current environmental and political pressure that is being placed on the consumption of fossil fuels, this subject has become even more critical. In the past, the presence of combustion instability could be avoided by designing a combustor with fixed inlet conditions, where these conditions were conducive to a stable system. Today, utilities and providers of propulsion systems are under pressure to make systems that are not only more efficient and clean, but also have a greater flexibility of input fuel. In order to accomplish this, combustion engineers need an even deeper insight into what causes thermoacoustic instability and they need a wider array of tools at their disposal to suppress these instabilities. This thesis adds pieces of that deeper insight and provides another tool to tackle this difficult problem. As a first step in the further understanding of thermoacoustic instabilities, experiments were done in a premixed gas backwards facing step combustor using propane or propane/hydrogen mixture as a fuel. I fully characterized the combustion dynamics in this combustor by measuring the four defining states of the system. These states are pressure, heat release, velocity, and equivalence ratio. Once these measurements were performed I tested two novel approaches to suppressing thermoacoustic instabilities through the use of microjet air injection. This was done by building upon a previous combustor setup to allow the installation of several new diagnostic capabilities and the new microjets.
(cont.) The new diagnostics include stand-off pressure sensors to measure pressure in the hot exhaust region, a hot wire anemometer to measure velocity, a photomultiplier tube to measure the integrated heat release, an automated gas probe to measure fuel concentration profiles, and a laser absorption sensor to measure the temporal variance in equivalence ratio. The novel microjets were built into the newly designed test section. By fully characterizing the system I was able to show how both equivalence ratio oscillations and wake vortex interactions drive the thermoacoustic instabilities of the combustion. I have also shown that the stability range shifts to leaner equivalence ratios as inlet temperature or hydrogen content in the fuel is increased. This thesis demonstrates the great potential the microjet air injection has for extending the range of stability of the system.
by Duane Edward Hudgins.
S.M.
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Chlouverakis, Konstantinos E. "Theory of dynamics of semiconductor lasers subject to optical injection." Thesis, University of Essex, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413642.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Pina, Estany Jordi. "Micro and nanostructures replication via injection moulding." Doctoral thesis, Universitat Ramon Llull, 2018. http://hdl.handle.net/10803/663803.

Повний текст джерела
Анотація:
Des del descobriment del poliestirè i el PVC a principis del segle XX, els plàstics han revolucionat el nostre dia a dia. Les 250 milions de tones que es fabriquen cada any s'utilitzen en un ampli ventall d'aplicacions com l'embalatge, la construcció, el transport, la medicina, l'electrònica, etc. D'una forma similar, es preveu que la nanotecnologia sigui una innovació disruptiva el segle XXI. Des que la nanotecnologia va néixer com a ciència als anys 80, han aparegut un ampli ventall d'aplicacions com els xips en laboratoris, les superfícies amb propietats d'autoneteja, les superfícies antimicrobianes, aplicacions òptiques, etc. Actualment, la nanotecnologia està saltant des dels centres de recerca cap a la indústria. Per fer això, el plàstic sembla ser un material adequat gràcies al seu baix cost, la fàcil fabricació i les propietats interessants com l'alta resistència tot i el baix pes, la durabilitat, la resistència a la corrosió, la transparència, etc. Aquesta tesi estudia en detall com l'injecció de plàstic es pot utilitzar per fabricar peces de plàstic amb àrees nanoestructurades. La dinàmica de fluids i la dinàmica molecular s'utilitzen per quantificar els paràmetres de procés i geomètrics que afecten la replicació. Des d'un punt de vista experimental i dins d'un marc de treball comú entre IQS (Universitat Ramon Llull), CSIC i Flubetech, s'injecta plàstic en motlles amb zones nanoestructurades i s'utilitza un microscopi de forces atòmiques per quantificar l'efecte en la replicació de la temperatura, el temps d'omplerta, la càrrega de polímer i la geometria de la nanocavitat. Per acabar, SEAT i l'IQS han unit esforços per desenvolupar una aplicació industrial centrada en la millora de l'homogeneïtat lumínica mitjançant el nanotexturitzat d'una superfície, s'ha obtingut d'aquesta manera un mètode més econòmic i eficient que els utilitzats actualment en l'il·luminació de fars i pilots.
Desde el descubrimiento del poliestireno y el PVC a principios del siglo XX, los plásticos han revolucionado nuestro día a día. Las 250 millones de toneladas que se fabrican cada año se utilizan en un ámplio abanico de aplicaciones como los embalajes, la construcción, los transportes, la medicina, la electrónica, etc. De una forma parecida, se prevé que la llegada de la nanotecnología sea un cambio disruptivo del siglo XXI. Desde que la nanotecnología nació como ciencia en los años 80, han aparecido distintas aplicaciones en distintos sectores como los laboratorios en chips, las superfícies autolimpiantes, las superfícies antimicrobios, aplicaciones ópticas, etc. Actualmente, la nanotecnología está saltando desde los centros de investigación a la industria. Para conseguir este salto, el plástico parece ser un material adecuado debido a su bajo coste, fácil fabricación y propiedades interesantes como su alta resistencia aún y su bajo peso, la resistencia a la corrosión, la transparencia, etc. Esta tesis estudia en detalle como la inyección de plástico se puede usar para fabricar piezas de plástico con zonas nanoestructuradas. La dinámica de fluidos computacional y la dinámica molecular se utilizan para cuantificar los parámetros de proceso y geométricos que afectan a la replicación. Desde el punto de vista experimental y en un trabajo conjunto entre IQS (Universidad Ramon Llull), CSIC y Flubetech, se inyecta plástico en moldes con superfícies nanoestructuradas y se analiza con un microscopio de fuerzas atómica el efecto en la replicación de la temperatura, el tiempo de llenado, la carga de polímero y la geometría de la nanocavidad. Para acabar, SEAT y IQS han unido esfuerzos para desarrollar una aplicación industrial centrada en la mejora de la homogeneidad lumínica mediante el nanotexturizado de una superficie, obteniendo así un método más económico y más eficiente que los métodos usados actualmente en iluminación de faros o pilotos.
Since polystyrene and PVC were discovered at the beginning of the 20th century, plastics have revolutionized our daily lives. The 250 millions of tonnes that are manufactured each year are used in a wide field of applications like packaging, building and construction, transportation, medical, electronics, etc. In a similar way, nanotechnology is called to lead a disruptive change on the 21th century. Since nanotechnology emerged as a science in the 1980s, a wide field of applications has appeared in different areas like lab-on-chips devices, surfaces with self-cleaning capabilities, antimicrobial surfaces, optical applications, etc. Currently, nanotechnology is jumping from the research area to the mass production industry. To do so, plastic appears to be a suitable material for its low cost, easiness to manufacture and interesting properties like high strength-to-weight ratio, durability, corrosion resistance, transparency, etc. This thesis studies in detail how injection moulding manufacturing technique can be used for manufacturing plastic parts with micro and nanostructured areas. Computational Fluid Dynamics and Molecular Dynamics simulation methods are used to quantify the process and geometrical factors that effect the replication. From the experimental point of view, in a common work between IQS (Ramon Llull University), CSIC and Flubetech, plastic is injected in moulds with nanostructured areas and an Atomic Force Microscope is used for quantifying the effect of temperature, filling time, polymer charge and nanoscale geometries in the replication of nanocavities. Finally, SEAT and IQS joined efforts to develop an industrial application consisting into an improve of light homogeneity through the nanotexturising of a surface, obtaining a costs reduction and a better efficiency than the currently used methods for lighting headlamps and rear lights.
Стилі APA, Harvard, Vancouver, ISO та ін.
5

Hohl, Angela. "Dynamics of semiconductor laser systems with optical injection and external feedback." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/29450.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Gomes, Vincent G. (Vincent Gracias). "The dynamics and control of melt temperature in thermoplastic injection molding /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65921.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Gao, Furong. "Measurement, dynamics and control of the mold temperature of injection molding." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=62000.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Ye, Ming, Raziuddin Khaleel, and Tian-Chyi J. Yeh. "Stochastic analysis of moisture plume dynamics of a field injection experiment." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 2004. http://hdl.handle.net/10150/615750.

Повний текст джерела
Анотація:
A vadose zone field injection experiment was conducted in the summer of 2000 at theHanford Site, Washington. The unique moisture content database is used to identify the lithology at the field site and to interpret, visualize, and quantify the spatio- temporal evolution of the three -dimensional (3 -D) moisture plume created by the injection experiment. We conducted a hierarchical geostatistical analysis to examine the large -scale geologic structure for the entire field site, and then investigate small -scale features within different layers. Afterward, variogram analysis is applied to the O field measured for seven different days during the injection experiment. Temporal variations of sills and ranges are related to the observed moisture plume dynamics. A visualization of the 3 -D moisture plume evolution illustrates effects of media heterogeneity. Statistics of changes in moisture content as a function of distance reveals large variance near the wetting front and the coefficient of variation increases with decreasing mean.These findings support the gradient- and mean -dependent variability in the moisture content distribution as reported by existing stochastic theories. Spatial moment analysis is also conducted to quantify the rate and direction of movement of the plume mass center and its spatial spreading. The ratio of horizontal to vertical spreading at varying moisture contents suggests moisture- dependent anisotropy in effective unsaturated hydraulic conductivity, confirming existing stochastic theories. However, the principal directions of the spatial moments are found to vary as the moisture plume evolves through local heterogeneity, a feature that has not been recognized in the theories.
Стилі APA, Harvard, Vancouver, ISO та ін.
9

Doumbia, Yaya. "Optical injection dynamics and polarization properties of semiconductor lasers frequency combs." Electronic Thesis or Diss., CentraleSupélec, 2021. http://www.theses.fr/2021CSUP0008.

Повний текст джерела
Анотація:
Dans ce travail, nous étudions la dynamique non linéaire de diodes laser injectées optiquement avec des peignes de fréquence.Nous analysons d'abord théoriquement et expérimentalement la dynamique non linéaire des lasers à émettant par la tranche (EELs) à partir d'une injection optique de peignes de fréquence. Les paramètres d'injection et les propriétés du peigne injecté sont variés pour dévoiler plusieurs dynamiques verrouillées et déverrouillées. Pour une force d'injection suffisamment grande et sur une large plage de désaccord, le verrouillage d'injection bifurque vers une dynamique temporelle correspondant à un peigne de fréquence optique qui étend le peigne injecté à un spectre optique beaucoup plus large. Une analyse de bifurcation révèle une dynamique de peigne de fréquence harmonique en cascade conduisant à une augmentation significative des lignes de peigne de sortie. Nous avons également utilisé les paramètres d'injection, les propriétés du peigne et le courant d'injection pour contrôler les propriétés du nouve peigne. Dans un deuxième temps, nous analysons expérimentalement la dynamique non linéaire et les propriétés de polarisation dans des lasers émettant par la surface (VCSEL) soumis à une injection optique orthogonale avec des peignes de fréquence. Plus important encore, le VCSEL montre deux peignes de fréquence avec une polarisation orthogonale à partir d'un seul appareil pour certains paramètres d'injection. Nous démontrons également la possibilité de contrôler le taux de répétition des peignes à une ou deux polarisations grâce à la génération de peignes à fréquence harmonique. Nous présentons enfin expérimentalement et théoriquement la dynamique d'injection de VCSEL à partir d'une injection de peigne de fréquence optique avec une polarisation parallèle à celle du VCSEL. Nous montrons que la performance des peignes à deux polarisations sont limitées à une injection de courant élevé dans le cas d'une injection optique parallèle. Pour un courant de polarisation fixe, la dynamique des deux peignes de polarisation disparaît lorsque l'on augmente l'espacement des peignes injectés.Cette thèse démontre donc outre son intérêt pour la dynamique laser non linéaire, l'injection optique est une technique permettant d'exploiter les propriétés de peigne dans les diodes laser
In this work, we study the nonlinear dynamics of laser diodes optically injected with frequency combs.We first theoretically and experimentally analyze the nonlinear dynamics of edge-emitting lasers (EELs) from an optical injection of frequency combs. The injection parameters and injected comb properties are varied to unveil several locked and unlocked dynamics. For large enough injection strength and over a large detuning range, the injection locking bifurcates to a time-periodic dynamics corresponding to an optical frequency comb that extends the injected comb to a much broader optical spectrum. A bifurcation analysis reveals a cascade harmonic frequency comb dynamics leading to a significant increase in the output comb lines. We have also used the injection parameters, comb properties, and injection current to control the new comb properties. We secondly analyze the nonlinear dynamics and polarization properties in vertical-cavity surface-emitting lasers (VCSELs) subject to orthogonal optical injection with frequency combs experimentally. Most importantly, the VCSEL shows two frequency combs with orthogonal polarization from a single device for some injection parameters. We also demonstrate the possibility to control the single or two polarizations comb repetition rate through harmonic frequency combs generation. We finally present experimentally and theoretically the VCSEL injection dynamics from parallel optical frequency comb injection. We show that the two polarizations combperformance is restricted to high current injection in the case of parallel optical injection. For fixed bias current, the two polarization comb dynamics disappear when increasing the injected comb spacing.This thesis therefore demonstrates besides its interest for nonlinear laser dynamics, optical injection is a technique to harness the comb properties in laser diodes
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Pastor, Diego Garcia. "The study of boundary layer control in a turbopump diffuser with fluid injection /." Online version of thesis, 1996. http://hdl.handle.net/1850/12290.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
Більше джерел

Книги з теми "Injection dynamics"

1

Flow injection atomic absorption spectrometry. Chichester: Wiley, 1995.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Austria) International Seminar "AVL Simulation Tools--Practical Applications" (2011 Graz. AVL simulation tools: Practical applications. Lublin: Politechnika Lubelska, 2012.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Steffen, Christopher J. Fuel injector design optimization for an annular scramjet geometry. [Cleveland, Ohio: NASA Glenn Research Center, 2003.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
4

N, Tiwari S., and United States. National Aeronautics and Space Administration., eds. Drag reduction on circular cylinders by ejecting jet from rear stagnation region: Progress report for the period ending June 30, 1997 ... under Cooperative Agreement NCC1-232. Norfolk, Va: Dept. of Mechanical Engineering, College of Engineering and Technology, Old Dominion University, 1997.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
5

Division, Rockwell International Rocketdyne, and United States. National Aeronautics and Space Administration., eds. The structural dynamics analysis of the main injector LOX inlet tee and its redesign. [Canoga Park, Calif: Rockwell International, Rocketdyne Division?, 1989.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Sun, Chang Q. Solvation Dynamics: A Notion of Charge Injection. Springer Singapore Pte. Limited, 2020.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Sun, Chang Q. Solvation Dynamics: A Notion of Charge Injection. Springer, 2019.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
8

King, John Barry. A study of buoyant backflow in vertical injection lines. 1991.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
9

King, John Barry. A study of buoyant backflow in vertical injection lines. 1991.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Cerda, Victor, Laura Ferrer, Jessica Avivar, and Amalia Cerda. Flow Analysis: A Practical Guide. Elsevier Science & Technology Books, 2014.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
Більше джерел

Частини книг з теми "Injection dynamics"

1

Armbruster, Wolfgang, Justin S. Hardi, and Michael Oschwald. "Experimental Investigation of Injection-Coupled High-Frequency Combustion Instabilities." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 249–62. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_16.

Повний текст джерела
Анотація:
Abstract Self-excited high-frequency combustion instabilities were investigated in a 42-injector cryogenic rocket combustor under representative conditions. In previous research it was found that the instabilities are connected to acoustic resonance of the shear-coaxial injectors. In order to gain a better understanding of the flame dynamics during instabilities, an optical access window was realised in the research combustor. This allowed 2D visualisation of supercritical flame response to acoustics under conditions similar to those found in European launcher engines. Through the window, high-speed imaging of the flame was conducted. Dynamic Mode Decomposition was applied to analyse the flame dynamics at specific frequencies, and was able to isolate the flame response to injector or combustion chamber acoustic modes. The flame response at the eigenfrequencies of the oxygen injectors showed symmetric and longitudinal wave-like structures on the dense oxygen core. With the gained understanding of the BKD coupling mechanism it was possible to derive LOX injector geometry changes in order to reduce the risks of injection-coupled instabilities for future cryogenic rocket engines.
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Otto, Christian. "Quantum Dot Laser Under Optical Injection." In Dynamics of Quantum Dot Lasers, 47–130. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-03786-8_3.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Mireault, R., R. Stocker, D. Dunn, and M. Pooladi-Darvish. "Dynamics of Acid Gas Injection Well Operation." In Acid Gas Injection and Related Technologies, 147–64. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118094273.ch10.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Chekmarev, S. F. "Gas or Isotope Separation by Injection into Light Gas Flow." In Rarefied Gas Dynamics, 1297–304. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2467-6_61.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
5

Ohtsubo, Junji. "Dynamics in Semiconductor Lasers with Optical Injection." In Springer Series in Optical Sciences, 169–204. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30147-6_6.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Ohtsubo, Junji. "Dynamics in Semiconductor Lasers with Optical Injection." In Springer Series in Optical Sciences, 183–225. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-56138-7_6.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Sezal, I. H., S. J. Schmidt, G. H. Schnerr, M. Thalhamer, and M. Förster. "Shock and wave dynamics in fuel injection systems." In Shock Waves, 925–30. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-85181-3_21.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Wang, Jian-Ping, and Ye-Tao Shao. "Rotating Detonation Engine Injection Velocity Limit and Nozzle Effects on Its Propulsion Performance." In Computational Fluid Dynamics 2010, 789–95. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-17884-9_100.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
9

Ortega, Miguel, Abel López-Villa, Guadalupe Juliana Gutiérrez, and Carlos A. Vargas. "Manufacturing of Polymeric Micro-Lenses by Drip Injection." In Fluid Dynamics in Physics, Engineering and Environmental Applications, 513–19. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-27723-8_49.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Mattsson, Ken. "Imposing Boundary Conditions with the Injection, the Projection and the Simultaneous Approximation Term Methods." In Computational Fluid Dynamics 2000, 343–48. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56535-9_50.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.

Тези доповідей конференцій з теми "Injection dynamics"

1

Kashchenko, Igor. "The harmonic injection technique for short-wave HF power amplifier." In 2017 Dynamics of Systems, Mechanisms and Machines (Dynamics). IEEE, 2017. http://dx.doi.org/10.1109/dynamics.2017.8239460.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
2

VAKILI, AHMAD, and CHRISTIAN GAUTHIER. "Control of cavity flow by upstream mass injection." In 22nd Fluid Dynamics, Plasma Dynamics and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1991. http://dx.doi.org/10.2514/6.1991-1645.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Borghi, M., M. Milani, and M. Piraccini. "Dynamic Analysis of Diesel Engine Common Rail Injection System: Part I — Injector Dynamics." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/fpst-25001.

Повний текст джерела
Анотація:
Abstract The aim of the paper is to analyze the dynamic behavior of an actual electro-hydraulic injector, included into a high-pressure accumulator injection system (Common Rail). Firstly, a brief introduction of the hypotheses adopted for a lumped parameter description of each part of an industrial version of the injector (BOSCH) is outlined, together with the definition of the hypotheses assumed to treat the fuel efflux through the injection holes, through the internal mechanical couplings and the damping orifices, or to descript of the cavitations. Then, the dynamic behavior of the injector is analyzed adopting some of the command signals imposed to the pilot stage by the Electronic Central Unit (ECU), as actually implemented into the standard map of an on board ECU of a industrial diesel engine. Among others, the paper presents the results coming from the injector handling for medium values of the crank-shaft regime (1800 and 2400 rpm), for different pressure levels in the Rail and involving also the pilot injection. The reliability of the numerical results is stated through a wide numerical vs. experimental comparison, made up on the basis of the fuel mass injected for each cycle. Finally, the discharge characteristics characterizing the injection are determined, such as the effective mean velocity and the effective area of the liquid core at the holes exit, or injection holes discharge coefficient.
Стилі APA, Harvard, Vancouver, ISO та ін.
4

HYDE, C., B. SMITH, J. SCHETZ, and D. WALKER. "Turbulence measurements for heated gas slot injection in supersonic flow." In 20th Fluid Dynamics, Plasma Dynamics and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1989. http://dx.doi.org/10.2514/6.1989-1868.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
5

BELL, JAMES, and RABINDRA MEHTA. "Effects of streamwise vorticity injection on turbulent mixing layer development." In 21st Fluid Dynamics, Plasma Dynamics and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1990. http://dx.doi.org/10.2514/6.1990-1459.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Tsuei, Hsin-Hua, and Charles Merkle. "Mixing and reaction in a combustor with transverse jet injection." In Fluid Dynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1995. http://dx.doi.org/10.2514/6.1995-2171.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Vu, Bruce T., Nicholas R. Moss, and Zoe Sampson. "Multi-Phase Modeling of Rainbird Water Injection." In 44th AIAA Fluid Dynamics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2014. http://dx.doi.org/10.2514/6.2014-3076.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Martens, G., O. Lukyanovych, and I. Filippenko. "Multipayload injection conception." In Progress in Flight Dynamics, Guidance, Navigation, Control, Fault Detection, and Avionics, edited by C. Vallet, D. Choukroun, C. Philippe, G. Balas, A. Nebylov, and O. Yanova. Les Ulis, France: EDP Sciences, 2013. http://dx.doi.org/10.1051/eucass/201306517.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
9

HOLLO, STEVEN, ROY HARTFIELD, JR., and JAMES MCDANIEL. "Injectant mole fraction measurements of transverse injection in constant area supersonic ducts." In 21st Fluid Dynamics, Plasma Dynamics and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1990. http://dx.doi.org/10.2514/6.1990-1632.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Sasaki, Kenta. "Numerical Simulation of Flow Dynamics for CO2 Injection into Rock Masses." In FLOW DYNAMICS: The Second International Conference on Flow Dynamics. AIP, 2006. http://dx.doi.org/10.1063/1.2204537.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.

Звіти організацій з теми "Injection dynamics"

1

Chin, Yong Ho. Beam-beam dynamics during the injection process at the PEP-II B-Factory. Office of Scientific and Technical Information (OSTI), October 1991. http://dx.doi.org/10.2172/10106667.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Chin, Yong Ho. Beam-beam dynamics during the injection process at the PEP-II B-Factory. Office of Scientific and Technical Information (OSTI), October 1991. http://dx.doi.org/10.2172/6100214.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Huang, Cheng, Rohan Gejji, William Anderson, Changjin Yoon, and Venkateswaran Sankaran. Combustion Dynamics Behavior in a Single-Element Lean Direct Injection (LDI) Gas Turbine Combustor. Fort Belvoir, VA: Defense Technical Information Center, June 2014. http://dx.doi.org/10.21236/ada611210.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Dr. Chenn Zhou. Computational Fluid Dynamics (CFD) Modeling for High Rate Pulverized Coal Injection (PCI) into the Blast Furnace. Office of Scientific and Technical Information (OSTI), October 2008. http://dx.doi.org/10.2172/949189.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
5

Frank, Jonathan H., Lyle M. Pickett, Scott E. Bisson, Brian D. Patterson, Adam J. Ruggles, Scott A. Skeen, Julien Luc Manin, Erxiong Huang, Dave J. Cicone, and Panos Sphicas. Quantitative Imaging of Turbulent Mixing Dynamics in High-Pressure Fuel Injection to Enable Predictive Simulations of Engine Combustion. Office of Scientific and Technical Information (OSTI), September 2015. http://dx.doi.org/10.2172/1331503.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Frese, M. H. Dynamics of plasma injection along magnetic field lines in the PBFA II (Particle Beam Fusion Accelerator II) plasma opening switch. Office of Scientific and Technical Information (OSTI), November 1989. http://dx.doi.org/10.2172/7161941.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Mitori, T. Flight and Stability of a Laser Inertial Fusion Energy Target in the Drift Region between Injection and the Reaction Chamber with Computational Fluid Dynamics. Office of Scientific and Technical Information (OSTI), December 2013. http://dx.doi.org/10.2172/1116962.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Henestroza, E., and D. Grote. Transient Beam Dynamics in the LBL 2 MV Injector. Office of Scientific and Technical Information (OSTI), December 1999. http://dx.doi.org/10.2172/15013501.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
9

Wolfenson, David, William W. Thatcher, and James E. Kinder. Regulation of LH Secretion in the Periovulatory Period as a Strategy to Enhance Ovarian Function and Fertility in Dairy and Beef Cows. United States Department of Agriculture, December 2003. http://dx.doi.org/10.32747/2003.7586458.bard.

Повний текст джерела
Анотація:
The general research objective was to increase herd pregnancy rates by enhancing corpus luteum (CL) function and optimizing follicle development, in order to increase conception rate and embryo survival. The specific objectives were: to determine the effect of the duration of the preovulatory LH surge on CL function; to determine the function of LH during the postovulatory period on CL development; to optimize CL differentiation and follicle development by means of a biodegradable GnRH implant; to test whether optimization of CL development and follicle dynamics in timed- insemination protocols would improve fertility in high-yielding dairy cows. Low fertility in cattle results in losses of hundreds of millions of dollars in the USA and Israel. Two major causes of low fertility are formation of a functionally impaired CL, and subsequent enhanced ovarian follicle development. A functionally impaired CL may result from suboptimal LH secretion. The two major causes of low fertility in dairy cattle in US and Israel are negative energy status and summer heat stress; in both situations, low fertility is associated with reductions in LH secretion and impaired development of the ovulatory follicle and of the CL. In Florida, the use of 450-mg deslorelin (GnRH analogue) implants to induce ovulation, under the Ovsynch protocol resulted in a higher pregnancy rates than use of 750-mg implants, and pregnancy losses tended to decrease compared to controls, due probably to decrease in follicular development and estradiol secretion at the time of conceptus signaling to maintain the CL. An alternative strategy to enhance progesterone concentrations involved induction of an accessory CL by injection of hCG on day 5 after the cows were inseminated. Treatment with hCG resulted in 86% of the cows having two CLs, compared with 23% of the control cows. Conception rates were higher among the hCG-treated cows than among the controls. Another approach was to replace the second injection of GnRH analogue, in a timed-insemination protocol, with estradiol cypionate (ECP) injected 24 h after the injection of PGF₂ₐ Pregnancy rates were comparable with those obtained under the regular Ovsynch (timed- AI) program. Use of ECP induced estrus, and cows inseminated at detected estrus are indeed more fertile than those not in estrus at the time of insemination. Collectively, the BARD-supported programs at the University of Florida have improved timed insemination programs. In Ohio, the importance of the frequency of LH episodes during the early stages of the estrous cycle of cattle, when the corpus luteum is developing, was studied in an in vivo experiment in which cows were subjected to various episodic exposures to exogenous bovine LH. Results indicate that the frequent LH episodes immediately following the time of ovulation are important in development of the corpus luteum, from the points of view of both size and functionality. In another study, rates of cell proliferation and numbers of endothelial cells were examined in vitro in CLs collected from cows that received post-ovulation pulsatile LH treatment at various frequencies. The results indicate that the corpora lutea growth that results from luteal cell proliferation is enhanced by the episodes of LH release that occur immediately after the time of ovulation in cattle. The results also show that luteal endothelial cell numbers did not differ among cows treated with different LH doses. In Israel. a longer duration of the preovulatory LH surge stimulated the steroidogenic capacity of granulosa-derived luteal cells, and might, thereby, contribute to a higher progesterone output from the bovine corpus luteum. In an in vivo study, a subgroup of high-yielding dairy cows with extended estrus to ovulation interval was identified. Associated with this extended interval were: low plasma progesterone and estradiol concentrations and a low preovulatory LH surge prior to ovulation, as well as low post- ovulation progesterone concentration. In experiments based on the above results, we found that injection of GnRH at the onset of estrus increased the LHpeak, prevented late ovulation, decreased the variability between cows and elicited high and uniform progesterone levels after ovulation. GnRH at estrus onset increased conception rates, especially in the summer, and among primiparous cows and those with low body condition. Another study compared ovarian functions in multiparous lactating cows with those in nulliparous non-lactating heifers. The results revealed differences in ovarian follicular dynamics, and in plasma concentrations of steroids and gonadotropins that may account for the differences in fertility between heifers and cows.
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Wolfenson, David, William W. Thatcher, Rina Meidan, Charles R. Staples, and Israel Flamenbaum. Hormonal and Nutritional Stretegies to Optimize Reproductive Function and Improve Fertility of Dairy Cattle during Heat Stress in Summer. United States Department of Agriculture, August 1994. http://dx.doi.org/10.32747/1994.7568773.bard.

Повний текст джерела
Анотація:
The BARD program includes two main parts. In the first, experiments were conducted to complete our understanding of the mechanisms responsible for the impairment of reproductive functions under heat stress. Experiments focused on follicular development and function, since results obtained in our previous BARD project indicate that the preovulatory follicle is susceptible to heat stress. The theca cells, sensitive to thermal stress, produced less androgen during the summer, as well as during the autumn. Similarly, luteinized theca cells obtained from cows in summer produced much less progesterone than in winter. Granulosa cells and luteinized granulosa cells were less susceptible to heat stress. A delayed effect of heat stress on follicular development, on suppression of dominance and on steroid production by theca and granulosa cells was noted. This may be related to the low fertility of cows during the cool months of autumn. In the second part, experiments were conducted aiming to improve fertility in summer. The timed AI program was developed using two injections of GnRH coupled with PGF2a. It was found effective in improving reproductive performance in lactating cows. Limitations induced by heat stress on estrus detection were eliminated with the timed AI management program. Replacing the second injection of GnRH with hCG instead of GnRH agonist increased plasma progesterone levels post ovulation but did not improve fertility. Use of the timed AI program in summer, shortened days open and increased the net revenue per cow, however, it did not protect the embryo fiom temperature-induced embryonic mortality. Incorporation of a GnRH-agonist implant into the timed AJ program was examined. The implant increased plasma progesterone and LH concentrations and altered follicular dynamics. The use of a GnRH-implant enhanced pregnancy rate in cows with low body conditions. In a timed embryo transfer experiment, the use of fresh or frozen in vitro produced embryos was compared in the summer to improve fertility. The use of flesh embryos (but not frozen ones) improved pregnancy rate, however, substantial embryonic death occurred between 21 and 45 days. The timed AI program, which is now being used commercially, shortened days open, and increased pregnancy rate during summer. Other approaches which were found to improve fertility in small-scale studies, need to be tested again in large-scale field trials.
Стилі APA, Harvard, Vancouver, ISO та ін.
Також вас можуть зацікавити розширені добірки на тему "Injection dynamics" для конкретних типів джерел:
Статті в журналах Дисертації Книги
Ми пропонуємо знижки на всі преміум-плани для авторів, чиї праці увійшли до тематичних добірок літератури. Зв'яжіться з нами, щоб отримати унікальний промокод!

До бібліографії