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1
Болотнікова, О. О. "Розрахунок і аналіз характеристик струминно-реактивної розширювальної машини". Master's thesis, Сумський державний університет, 2020. https://essuir.sumdu.edu.ua/handle/123456789/82242.
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В роботі отримані параметри ефективності СРТ на виході (сила тяги, пусковий момент, питомий пусковий момент, коефіцієнт відновлення повного тиску в проточній частині СРТ) при різних тисках на вході (2,4 МПа, 4,9 МПа, 7,4 МПа) за допомогою програмного комплексу FlowVision. Отримані залежності пускового моменту і питомого пускового моменту на валу ротора СРТ від зміни критичних діаметрів підвідного та тягового сопел, а також від зміни вихідного діаметра тягового сопла. Досліджено вплив степені нерозрахунковості тягового сопла струминно-розширювальної турбіни на її ефективність.<br>В работе получены параметры эффективности СРТ на выходе (сила тяги, пусковой момент, удельный пусковой момент, коэффициент восстановления полного давления в проточной части СРТ) при различных давлениях на входе (2,4 МПа, 4,9 МПа, 7,4 МПа) с помощью программного комплекса FlowVision. Получены зависимости пускового момента и удельного пускового момента на валу ротора СРТ от изменения критических диаметров подводящего и тягового сопел, а также от изменения выходного диаметра тягового сопла. Исследовано влияние степени нерасчетности тягового сопла струйно-расширительной турбины на ее эффективность.<br>In the work, the parameters of the efficiency of the jet-jet turbine at the outlet (thrust force, starting torque, specific starting torque, the coefficient of recovery of the total pressure in the flow path of the jet-jet turbine) at various inlet pressures (2.4 MPa, 4.9 MPa, 7, 4 MPa) using the FlowVision software package. The dependences of the starting torque and the specific starting torque on the rotor shaft of the jet-jet turbine on the change in the critical diameters of the supply and thrust nozzles, as well as on the change in the outlet diameter of the thrust nozzle are obtained. The influence of the degree of non-design of the thrust nozzle of the jet-expansion turbine on its efficiency is investigated.
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Spiekermann-Hoff, Sarah, and Jana Korunovska. "Towards a value theory for personal data." Palgrave Macmillan, 2017. http://dx.doi.org/10.1057/jit.2016.4.
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Analysts, investors and entrepreneurs have recognized the value of personal data for Internet economics. Personal data is viewed as the "oil" of the digital economy. Yet, ordinary people are barely aware of this. Marketers collect personal data at minimal cost in exchange for free services. But will this be possible in the long term, especially in the face of privacy concerns? Little is known about how users really value their personal data. In this paper, we build a user-centered value theory for personal data. On the basis of a survey experiment with 1269 Facebook users, we identify core constructs that drive the value of volunteered personal data. We find that privacy concerns are less influential than expected and influence data value mainly when people become aware of data markets. In fact, the consciousness of data being a tradable asset is the single most influential factor driving willingness-to-pay for data. Furthermore, we find that people build a sense of psychological ownership for their data and hence value it more. Finally, our value theory helps to unveil market design mechanisms that will influence how personal data markets thrive: First, we observe a majority of users become reactant if they are consciously deprived of control over their personal data; many drop out of the market. We therefore advice companies to consider user-centered data control tools to have them participate in personal data markets. Second, we find that in order to create scarcity in the market, centralized IT architectures (reducing multiple data copies) may be beneficial.
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Peters, Jacob R., Robert Keasling, Stacy D. Brown, and Brooks B. Pond. "Quantification of Synthetic Cathinones in Rat Brain Using HILIC–ESI-MS/MS." Digital Commons @ East Tennessee State University, 2016. https://doi.org/10.1093/jat/bkw074.
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The abuse of synthetic cathinones, formerly marketed as “bath salts”, has emerged over the last decade. Three common drugs in this class include 3,4-methylenedioxypyrovalerone (MDPV), 4-methylmethcathinone (mephedrone), and 3,4-methylenedioxymethcathinone (methylone). An LC–MS/MS method has been developed and validated for the simultaneous quantification of MDPV, mephedrone, and methylone in brain tissue. Briefly, MDPV, mephedrone, methylone, and their deuterium-labeled analogs were subjected to solid phase extraction (SPE) and separated using an HILIC Silica Column. The HPLC was coupled to a Shimadzu IT-TOF (ion trap-time of flight) system with the electrospray source running in positive mode (+ESI). The method was validated for precision, accuracy, and extraction efficiency. All inter-day and intra-day % RSD (percent relative standard deviation) and % error values were less than 15% and extraction efficiency exceeded 80%. These conditions allowed for limits of detection of 1ng/mL for MDPV, and 5 ng/mL for both mephedrone and methylone. The limits of quantification were determined to be 5ng/mL for MDPV and 10 ng/mL for mephedrone and methylone. The method was utilized to evaluate the pharmacokinetics of these drugs in adult male rats following administration of a drug cocktail including MDPV, mephedrone, and methylone. All three compounds reached peak concentrations in the brain within 15 min. Although methylone and mephedrone were administered at the same dose, the peak concentration (Cmax) of mephedrone in the brain was significantly higher than that for methylone, as was the area under the curve (AUC). In summary, this quick and sensitive method for measuring synthetic cathinones may be used for future pharmacokinetic investigations of these drugs in target tissue.
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Leder, Garth Duncan. "Jet rates and new jet algorithms." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624739.
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Tyagi, Ashok K. "Jet to jet impingement in a confined space." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30117.pdf.
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Sellas, Alexis B. "Ghost-Jet." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/352.
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GHOST-JET is a collection of poems rooted in the lyrical tradition, often juxtaposing images of the natural world--the human body, insects, the Florida terrain--against images of surrealism--ethereal spirits, monsters, dreamscapes--in order to create metaphorical leaps of the imagination. In these poems there is the world as we know it and the world on the peripheral--zombies and babies turning into crocodiles, portraying the anxieties of the contemporary world we face as parents, children, and citizens. Written primarily in free verse, the collection also contains more traditional forms: pantoum, sestina, and haiku. There are no section breaks in this collection. Instead, the poems alternate between the personal and the political; between the particular fears of parenting and the more abstract fears in a new, post-September 11th America; between the violence perpetuated by family members and violence committed by the unknown, faceless aggressors in the world around us.
7
Klymenko, К., and L. M. Meleshkevych. "Jet pack." Thesis, КНУТД, 2016. https://er.knutd.edu.ua/handle/123456789/5047.
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Kiran, Amit. "Jet noise : aeroacoustic distribution of a subsonic co-axial jet." Thesis, University of Warwick, 2008. http://wrap.warwick.ac.uk/3914/.
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The noise generated by aircraft can be easily heard by those living under the flight path of passenger or cargo carriers. It is considered an environmental pollutant and is treated as such by the International Civil Aviation Organization (ICAO) who monitor and review noise levels. The ICAO imposes substantial fines on those carriers who do not adhere to the decibel limitations. With the new limit or `stage' enforced in 2006, aircraft manufacturers (including jet engine manufacturers) are seeking ways to reduce the noise created by an aircraft. A 1/150th scale model, based on the exit geometry typically found on commercial jet engines, was designed and manufactured at Warwick. The laboratory jet flow conditions operated at 0.7 Mach. The work presented in this thesis looks at the noise generated in a subsonic, co- owing jet, with particular focus given to the distribution sound sources from 5 kHz to 80 kHz (0.375 St to 6.0 St). An acoustic mirror mounted on a motorized 3-way traverse measured radiated sound in the co-flowing jet to produce 2D sound source maps. This is done using combinations of smooth cowl and chevrons for the core and bypass nozzles. For frequencies less than 30 kHz, a reduction of noise was observed using the bypass chevron nozzle compared with the bypass smooth cowl nozzle. Laser Doppler Anemometry (LDA) was used to reveal the 2D flow dynamics of the jet, supporting the acoustic distribution results with velocity profiles of the flow. The change in the flow dynamics with different nozzle combinations is discussed and different regions of the flow were identified.
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Varley, Juliet. "Submerged jet oxygenation." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334290.
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Lyu, Benshuai. "Installed jet noise." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/273735.
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This thesis studies the prediction and reduction of installed jet noise, combining both analytical and experimental techniques. In the prediction part, it starts with formulating a low-order but robust isolated jet noise prediction model, based on which a remarkably fast code with pre-informed data is developed. A semi-empirical low-order model is then developed to predict installed jet noise. The model consists of two parts, the first of which is based on the Lighthill's acoustic analogy theory. The second part embraces Amiet's approach to model the sound due to the scattering of jet instability waves. It is shown that the significant low-frequency noise enhancement observed in installed jet experiments is due to the scattering of near-field instability waves. The trailing edge scattering model can successfully predict noise spectra at all distinct angles. The quadrupole-induced high-frequency sound is either efficiently shielded at $90^\circ$ to the jet axis on the shielded side or enhanced by around $3$ dB at $90^\circ$ on the reflected side. But these effects gradually diminish as the observer angle decreases. The high-frequency spectra can be robustly predicted at large observer angles while deviation occurs at low observer angles due to jet refraction effects. An experimental study on installed jet noise is then conducted. The effects of plate positions and Mach numbers are studied. Excellent agreement between the experimental results and model predictions is achieved at low frequencies for all plate positions and Mach numbers tested. At high frequencies, the noise spectra at $90^\circ$ on the reflected side can also be correctly predicted. At lower observer angles, deviations occur due to jet refraction effects. In the noise reduction part, an experimental study is firstly carried out to study the effects of lobed nozzles on installed jet noise at constant flow rates. It is found that lobed nozzles do not noticeably change the installed jet noise spectra at low frequencies. However, they do result in a slight noise reduction at high frequencies. To understand why lobed nozzles hardly change low-frequency installed jet noise, an analytical stability analysis for lobed vortex sheets is performed. The results show that lobed jets change both the convection velocity and the temporal growth rate of instability waves. The changes become more pronounced as the number of lobes $N$ and the penetration ratio $\epsilon$ increase. A second set of experiments is carried out to explore the possibility of reducing installed jet noise by using two pylons. The results show that even in the most conservative case installed jet noise is reduced by around $2\sim3$ dB at low frequencies. It is concluded that using two pylons to reduce installed jet noise has significant practical potential.
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Ritchie, Brian Douglas. "Quantitative Acetone PLIF Measurements of Jet Mixing with Synthetic Jet Actuators." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10536.
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Fuel-air mixing enhancement in axisymmetric jets using an array of synthetic jet actuators around the perimeter of the flows (primarily parallel to the flow axis) was investigated using planar laser-induced fluorescence of acetone. The synthetic jets are a promising new mixing control and enhancement technology with a wide range of capabilities. An image correction scheme that improved on current ones was applied to the images acquired to generate quantitative mixing measurements. Both a single jet and coaxial jets were tested, including different velocity ratios for the coaxial jets. The actuators run at a high frequency (~1.2 kHz), and were tested with all of them on and in other geometric patterns. In addition, amplitude modulation was imposed at a lower frequency (10-100 Hz).
The actuators generated small-scale structures in the outer (and inner, for the coaxial jets) mixing layers. These structures significantly enhanced the mixing in the near field (x/D less than 1) of the jets, which would be useful for correcting an off-design condition in a combustor. The amplitude modulation generated large-scale structures that became apparent farther downstream (x/D greater than 1). The impulse at the start of the duty cycle was responsible for creating the structures. The large structures contained broad regions of uniformly mixed fluid, and also entrained fluid significantly. In addition, highly asymmetric forcing geometries displayed the power of the actuators to control the spatial distribution of jet fluid. This spatial control is important for the correction of hot spots in the pattern factor.
In order to extend quantitative acetone PLIF to two-phase flows, the remaining unknown photophysical properties of acetone were identified. Tests showed that the technique could simultaneously capture acetone vapor and acetone droplets. A model of droplet fluorescence was developed, and applied to images acquired in a dilute spray. The sensitivity of the model to the value of the unknowns was evaluated, including a best and worst case. The results revealed that several liquid acetone photophysical properties must be measured for the further development of the technique, especially the phosphorescence yield. Quantitative two-phase acetone PLIF will provide a powerful new tool for studying spray flows.
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Bilgin, Murat. "Stationary and rotating hot jet ignition and flame propagation in a premixed cell /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9986.
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Loizides, Constantinos A. "Jet physics in ALICE." Stuttgart Ibidem-Verl, 2005. http://deposit.ddb.de/cgi-bin/dokserv?id=2672387&prov=M&dok_var=1&dok_ext=htm.
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Clements, Daniel Robert. "Jet physics at ATLAS." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/365/.
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The use and optimisation of integration grid techniques to generate next-to-leading order predictions of jet cross-sections, independent of parton distribution functions, was investigated. Such methods were found to provide an accurate approximation to a standard Monte-Carlo simulation (within 1%) and enable collider data to be readily included in global PDF fitting procedures. However, the benefit of including inclusive-jet cross-section data from ATLAS in global fits is only significant if the jet energy scale (JES) can be constrained to ~1% at high pT. Uncertainties in the theoretical prediction of the inclusive-jet cross-section such as PDFs and fixed-order (scale) uncertainties were studied and compared with experimental errors arising from jet energy resolution and absolute scale. These uncertainties were then considered in the context of a quark compositeness search where a sensitivity to a compositeness scale of Lambda<10TeV can be achieved with 10 inverse femtobarns of data, if the jet energy scale can be constrained to ~1%. An analysis using dijet angular distributions found a similar sensitivity without the dependence on the jet energy scale. A potential method of evaluating the stability of the jet energy scale out to high pT by `bootstrapping' the calibration at low pT by the use of multi-jet events was also investigated. This suggests that a calorimeter non-linearity can be detected for jets with pT>500GeV at ~1.5%/500GeV (i.e. a 1.5% change in JES over 500GeV in pT). An investigation of inner-detector commissioning issues associated with the ATLAS Semiconductor Tracker (SCT), including a review of `noisy' modules on the SCT Barrel (from May 2007) was carried out. In addition a tool for DCS monitoring within the online monitoring framework was developed and tested during the M5 and M6 commissioning weeks. Finally, a method of assessing the track reconstruction efficiency by track-insertion was considered for the particular case of minimum bias events.
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Sanders, John E. "Jet dispersion in channels." Thesis, University of East London, 1998. http://roar.uel.ac.uk/1254/.
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This is an experimental and theoretical investigation of the dispersion of a round water jet discharging at various angles into a rectangular channel. A fundamental study of the jet is not only essential for a better understanding of the flow conditions produced by confined water jets but for a scientific approach to the design of hydraulic structures and to determine an efficient form of stilling basin for high velocity discharge from pipe outlets. The Laser Doppler Anemometry (LDA) technique was adapted for measurement of mean velocities and turbulence characteristics,, without any interference in the flow, and was utilised for the investigation of the complex three dimensional circulating flow which was experienced in the channel. In the experiments the inclination of the jet was varied from 45 to 90 degrees to the bed of the channel, while differing ratios of channel width and depth to jet diameter were studied for various Froude numbers. Detailed measurements of velocity decay, normal and lateral velocity profiles, distributions of pressure and turbulence characteristics have been carried out for selected flow conditions relating to the 45 degree oblique and vertical jet in order to determine the flow pattern and head dissipations. The experimental results have been analysed and compared with Glauert Is theory for a radial wall jet as a first approximation neglecting gravity forces when small compared with turbulent forces. Based on these results erosion experiments and model studies using a solid apron and a sand bed downstream, have been conducted to predict the minimum size of an efficient stilling basin and dimensions of any required blocks. Finally generalised design guide-lines and a standard code of practice have been developed for a stilling basin with high velocity pipe outlets. The research work will provide practical information and design procedures for consultants and other organisations working on the design and maintenance of a variety of water projects both in the UK and overseas.
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Maurel, Agnès. "Instabilité d'un jet confiné." Paris 6, 1994. http://www.theses.fr/1994PA066771.
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Une etude experimentale et numerique est menee sur l'oscillation auto-entretenue d'un jet bidimensionnel dans une cavite rectangulaire. L'etude experimentale permet de preciser les differents regimes observes lorsque la vitesse d'entree du jet et la longueur de la cavite varient. Une etude plus detaillee du regime d'oscillations auto-entretenues est presentee. Elle met en evidence l'existence de modes (stages), caracterises par une longueur d'onde constante verifiant l=(n+1/4), ou l est la longueur de la cavite ; la valeur n selectionnee depend de la largeur d'entree du jet et de la vitesse d'entree du jet. Le mecanisme d'amplification presume est fonde sur un modele de synchronisation entre l'oscillation a la sortie de la cavite et les perturbations declenchees a l'entree du jet. L'etude numerique est menee sur une cavite carree (les simulations 2d sont effectuees avec le code de calcul nekton, fonde sur une methode d'elements finis spectraux) et s'attache a decrire l'instabilite proche du seuil. Une frequence fondamentale est degagee en regime lineaire et les non-linearites font apparaitre l'harmonique 2 et un mode stationnaire de frequence nulle ; elle modifie le motif de l'ecoulement moyen. Le developpement de cet ecoulement moyen est le mecanisme de saturation de l'instabilite oscillante: il stabilise les profils de vitesse. Une methode d'analyse en modes est presentee, qui tente de degager des grandeurs caracteristiques de l'instabilite. Les methodes d'exploitation des resultats des simulations sont applicables dans d'autres geometries et, en particulier, les resultats presentes dans cette these sont comparables a ceux mis en evidence dans des etudes numeriques du sillage
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Hossain, Mohammad Arif. "Sweeping Jet Film Cooling." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586462423029754.
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Majerčin, Jakub. "Podnikatelský záměr - Business Jet." Master's thesis, Vysoká škola ekonomická v Praze, 2012. http://www.nusl.cz/ntk/nusl-162957.
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The aim of this thesis is to develop a business plan for the establishment of private airlines in the Czech Republic, based in Prague. The first part describes the theoretical part of the business plan. Its contents are facts that business plan should include, describes the practical meaning of this work and the reason for its assembly. Theoretical part describes in detail each part of the business plan and defines methods which are used in the practical part. The second part of this thesis deals with the transfer of theory into practical application. The practical part describes a preparation of the business plan, the establishment of private airlines. The content of the business plan is the executive summary, organizational structure, description of services offered, operation and analysis of competition and market. There are also accurately described activities of business, risk analysis and financial plan. The financial plan is created for five years in business and it has three possible variants of development. The conclusion contains a summary of the project and recommendations.
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Ho, Chu Eu. "Turbulent fluid jet excavation in cohesive soil : with particular application to jet grouting." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32416.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2005.<br>Includes bibliographical references (p. 267-271).<br>This thesis reviews the jet grouting methodology, and the current state of practice and research. Current methods of prediction of jet grout diameters are highly empirical and site specific, and do not take into account the jet hydrodynamics and soil properties explicitly. A rational model to describe the jet excavation mechanism for cohesive soil is presented in this thesis, with the aim of providing an improved prediction tool that can be used in jetting design. The model is based on the assumption that the velocity distribution in the cutting jet is equivalent to that of a free jet with boundaries corresponding to the dimensions of the cavity excavated in the ground. The shape of the cavity formed depends on the erosional properties of the soil and jet expansion is limited by the resistance at the jet-soil interface. It is hypothesized that the shape of the cavity excavated follows the locus of the jet radius satisfying the condition of constant wall shear stress. The model predicts that the limit of jet penetration is reached when the dynamic pressure at the jet tip becomes equal to the ultimate soil bearing resistance. The model was validated by laboratory jetting tests, using soil specimens manufactured from powdered kaolin clay, cement and water. Cement-soil ratios (CSR) of 2.5 to 7.5% were used to produce specimens with undrained shear strength (Su) ranging from 5 to 45 kPa. A period of at least 3 days was allowed for the specimen to cure in the test tank before jetting was commenced. The tests were conducted using different nozzle diameters, jetting pressures, rotation speeds and soil strengths. The specimens were exhumed after completion of each test to map the shape of the cuts excavated.<br>(cont.) The insitu shear strength of the specimens was obtained using torvane and laboratory vane shear tests. Samples were also obtained for density and moisture content measurements. The experimental results showed that the measured and predicted shapes of cut were in reasonable agreement, with the predicted jet width being conservative in most cases. A strong linear correlation was found between jet penetration, nozzle diameter, nozzle pressure difference and soil bearing capacity. It was found that a bearing capacity coefficient (Sc) of 2.4 was applicable for failure at the jet tip. This value of Sc was corroborated by field trial data. Wall shear stresses back-calculated from the experiments were much smaller than the residual soil strengths obtained from laboratory vane shear tests and correspond more closely to the erosional strength of clays. The model enables the lift step of the jetting monitor to be computed directly. The present research demonstrated that valuable information regarding the excavation mechanism can be obtained by careful examination of the actual cut in a soil formed by a jet. It is recommended that further work be done to investigate the erosional process at the jet-soil interface and the properties of the grouted soil, using higher jetting pressures and soils with higher shear strengths. The effect of withdrawal rate on column formation and uniformity of mix is of interest. The brittleness of the grouted product and its effect on strength and deformation behavior is also important.<br>Chu Eu Ho.<br>Sc.D.
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Monoté, Guy. "Atomisation d'un jet liquide par un jet de gaz coaxial : analyse du mélange." Poitiers, 1994. http://www.theses.fr/1994POIT2286.
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Cette etude contribue a la modelisation de la pulverisation d'un jet liquide par un jet de gaz coaxial. La configuration de jets diphasiques mise en place est une simulation de l'injection coaxiale generee avec de l'oxygene liquide lox et de l'hydrogene gazeux gh#2 dans le moteur cryotechnique vulcain de la fusee ariane v. La visualisation de jets d'eau ou de solutions aqueuses d'un tensioactif, assistes par des jets d'air, par l'intermediaire d'une nappe laser stroboscopee, fournit des photographies utiles a la comprehension de la structure des jets coaxiaux. Les mesures du taux de presence de liquide, effectuees au moyen d'une fibre optique, dans la zone dense des pulverisations, ont permis de mettre en evidence l'interaction entre les deux ecoulements adjacents. En particulier, elles montrent que le gaz penetre tres tot dans le liquide en formant une surface d'echange complexe. D'autre part, ces mesures ont rendu possible la classification des jets coaxiaux liquide/gaz en deux regimes d'ecoulement distincts, fonctions des conditions initiales d'injection. La mise en equation du taux de presence axial de liquide dans le voisinage de l'injecteur nous a conduit a proposer une correlation destinee a la prediction de la longueur de rupture du jet diphasique. Un analyseur de particules par la methode des phases doppler (pdpa) a servi a l'exploration de la zone diluee des jets. La taille des gouttes, leur vitesse axiale moyenne ou fluctuante ont ete determinees. Enfin, une premiere approche du bilan de masse montre que la zone centrale dense des jets coaxiaux se caracterise par un glissement entre les phases
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Smith, Matthew James. "The Analysis and Prediction of Jet Flow and Jet Noise about Airframe Surfaces." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23897.
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Aircraft noise mitigation has been an ongoing challenge for the aeronautics research community. In response to this challenge, aircraft concepts have been developed in which the
propulsion system is integrated with the airframe to shield the noise from the observer.
These concepts exhibit situations where the jet exhaust interacts with an airframe surface.
Jet flows interacting with nearby surfaces exhibit a complex behavior in which acoustic and
aerodynamic characteristics are altered. The physical understanding and accurate modeling
of these characteristics are essential to designing future low-noise aircraft. In this thesis,
an alternative approach is created for predicting jet mixing noise that utilizes an acoustic
analogy and the solution of the steady Reynolds-Averaged Navier-Stokes (RANS) equations
using a two equation turbulence model. A tailored Green's function is used in conjunction
with the acoustic analogy to account for the propagation effects of mixing noise due to a
nearby airframe surface. The tailored Green's function is found numerically using a newly
developed ray tracing method. The variation of the aerodynamics, acoustic source, and far-
field acoustic intensity are examined as a large flat plate is moved relative to the nozzle exit.
Steady RANS solutions are used to study the aerodynamic changes in the field-variables and
turbulence statistics. To quantify the propulsion airframe aeroacoustic (PAA) installation
effects on the aerodynamic source, a non-dimensional number is formed that can be used
as a basic guide to determine if the aerodynamic source is affected by the airframe and if
additional noise produced by the airframe surface is present. The aerodynamic and noise
prediction models are validated by comparing results with Particle Image Velocimetry (PIV)
and far-field acoustic data respectively. The developed jet noise scattering methodology is
then used to demonstrate the shielding effects of the Hybrid Wing Body (HWB) aircraft.
The validation assessment shows that the acoustic analogy and tailored Green's function
provided by the ray tracing method are capable of capturing jet shielding characteristics for
multiple configurations and jet exit conditions.<br>Master of Science
22
Tipnis, T. J. "Effects of upstream nozzle geometry on rectangular free jets." Thesis, Depatment of Engineering Systems and Mangement, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4557.
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This study is aimed at understanding the effects of changing the upstream nozzle geometry on the development of rectangular free jets. An existing converging rectangular nozzle with an exit aspect ratio of 4 and a circular inlet (AR4 nozzle) has been used as the basic configuration for this work. The study is primarily based on the results of numerical simulations wherein the internal geometry variation is accomplished by changing the inlet aspect ratio (AR,) and the length of the converging section, expressed as a ratio with respect to the length of the nozzle (called 'converging section ratio*, CSR); all the other parameters are kept constant. The results from LDA experiments done on the AR4 nozzle are presented and used as validation data for the CPD simulations. Analyses of the numerical results help in understanding the variation of the jet spreading for different combinations of AR, and CSR. Two parameters are identified for describing the jet development: the cross-over point (XC), defined as the location downstream of the exit where the jet half-velocity-widths (B) along the major and minor axes are equal, and the difference in the half-velocity-widths at 30 nozzle equivalent diameters (Dm) from the exit (AB30), to ascertain the occurrence of axis-switching. For a given AR,, XC varies linearly with CSR; the variation of XC is non-linear with AR, for a constant CSR. The A1330 variation is non-linear with both AR, and CSR; the other variable being kept constant. The data obtained from the simulations are further used to propose two parametric models which can be used to predict the occurrence of axis-switching, within the scope of this work. The parametric models are validated and future work is proposed.
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Sivapragasam, M. "Numerical and experimental investigations on multiple air jets in counterflow for generating aircraft gas turbine engine inlet flow distortion patterns." Thesis, Coventry University, 2014. http://curve.coventry.ac.uk/open/items/0ad1d0c2-6693-4c6e-9224-5a2237862074/1.
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The performance of an aircraft gas turbine engine is adversely affected by the non-uniform or distorted flow in the inlet duct. Inlet flow distortion lowers the surge margin of the engine‟s compression system with surge occurring at much lower pressure ratios at all engine speeds. The compressor and/or engine are subjected to ground tests in the presence of inlet distortion to evaluate its performance. The simplest method of simulating inlet distortion during these tests is by installing a distortion screen ahead of the engine on the test bed. The uniform inlet flow to the compressor becomes nonuniform with total pressure loss after passing through the distortion screen. Though the distortion screens offer a number of significant advantages, they have some disadvantages. The air jet distortion system can alleviate many of the operational disadvantages encountered with the conventional distortion screens. The system consists of a number of air jets arranged in a circumferential array in a plane and issuing opposite to the primary air flow entering the engine. The jets interact with the primary stream and cause a local total pressure loss due to momentum exchange. The individual mass flow rates from the jets can be varied to obtain a required total pressure pattern ahead of the compressor at the Aerodynamic Interface Plane (AIP). A systematic study of the flow field of confined, turbulent, incompressible, axisymmetric jet issuing into counterflow is covered in this research programme. The jet penetration length and the jet width are reduced compared to unconfined counterflow and a linear relationship between the velocity ratio and the jet length ceases to be valid. The flow field of a circular compressible turbulent jet and then a system of four jets arranged circumferentially and issuing into a confined counterflow was studied experimentally and numerically. For the four jet system the mass flow rates in the four jets were equal in the first part of the study and in the second part they were unequal. The loss in total pressure due to the jet(s) interacting with the counterflow was quantified by a total pressure loss parameter λp0. The total pressure loss increased with increasing mass flow ratio. The total pressure loss distribution was evaluated at several locations behind the jet injector(s). The total pressure non-uniformity quantified by Distortion Index (DI) was found to be highest at a location just downstream of the jet injector and at far downstream locations low values of DI were observed. From the understanding gained with a single jet and four jets in counterflow a methodology was developed to generate a given total pressure distortion pattern at the AIP. The methodology employs computations to obtain the total pressure distortion at the AIP with quasi-one-dimensional inviscid analysis used as a starting point to estimate the mass flow rate in the jets. The inviscid analysis also provides a direction to the iterative procedure to vary the mass flow rate in the jets at the end of each computational step. The methodology is demonstrated to generate a given total pressure distortion pattern using four jets and is further extended to a larger number of jets, twelve and later twenty jets. The total pressure distortion patterns typical of use in aircraft gas turbine engine testing are generated accurately with a smaller number of jets than reported in the literature.
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Trzebinski, Maciej. "Etude de la diffraction dans l'experience ATLAS au LHC." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00908126.
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Cette thèse porte sur l'étude de la diffraction avec le détecteur ATLAS au LHC. Après une brève introduction a la physique diffractive incluant la diffraction dure et molle, nous présenterons la production d'évènements "Jet-Gap-Jet" qui est particulirement intéressante pour tester les équations d'évolution de la Chromodynamique Quantique de Balitski Fadin Kuraev Lipatov. En utilisant des coupures permettant de sélectionner ce signal et une définition du "gap" basée sur la reconstruction des traces dans le détecteur interne d'ATLAS, nous observons un signal clair d'évènements "Jet-Gap-Jet" dans les données. A partir d'une taille de "demi-gap" de 0.8, les données ne peuvent pas être décrites de manière correcte en utilisant l'échantillon Monte Carlo des données de jets sans gap. Nous prouvons également que la production d'évènements "Jet-gap-Jet" avec les deux protons détectes dans AFP permet de réaliser un test propre de la théorie BFKL avec une luminosité de 300 pb-1. Dans la derniere partie de la these, nous presentons la production exclusive de jets et de pi+pi-. Apres la selection des donnes, le rapport signal sur bruit est de l'ordre de 5/9 (1/13) pour µ = 23 (46). Pour une luminosite integree respective de 40(300) fb-1 (pour un "pile-up" de 23(46)), cette mesure permettra d'etablir des contraintes sur les modeles theoriques dix fois plus precises qu'actuellement. La mesure de la production exclusive de pions en utilisant le detecteur ALFA permet de contraindre egalement les modeles exclusifs. Nous avons montre que les donnees accumulees par ALFA suffiront deja pour mesurer la section efficace de production et pour etudier differentes distributions comme la masse invariante du systeme pion-pion.
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Belias, Anastasios. "Electron/jet discrimination and b-jet tagging at the second level trigger of ATLAS." Thesis, Royal Holloway, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326090.
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Kim, Yongsun Ph D. Massachusetts Institute of Technology. "Study of jet quenching using [gamma]-jet events in heavy ion collisions at 2.76TeV." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83825.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2013.<br>In title on title-page, "[gamma]" appears as the lower case Greek letter. Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 149-156).<br>The kinematic correlations of isolated-[gamma]+jet scatterings in proton-proton and lead-lead collisions at centre-of-mass energy of 2.76TeV per nucleon pair are studied for the investigation of the jet quenching phenomena in hot and dense QCD medium. The analysis uses collision data delivered by the LHC and recorded by CMS detector at CERN. The angular correlation, the transverse momentum ratio and the rate of mono-photon events are measured and their dependence on the collisional impact parameter is examined in lead-lead collision. The results of proton-proton collisions are used as the reference to which the lead-lead results are compared. Significant energy loss of jets induced by the hot and dense medium, and its gradual rise in correlation to the size of the medium are observed in lead-lead collisions, while a modification of the direction of jet axis is not detected.<br>by Yongsun Kim.<br>Ph.D.
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Solovev, Alexander Alexandrovich. "Catalytic Tubular Micro-Jet Engines." Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-92005.
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This dissertation offers demonstrations of autonomous catalytic microtubes (microjet engines) with tunable diameters ranging from micro- to nanoscale and lengths from 50 μm to 1 mm. These results open the door to effective microengines and represent the entry in the Guinness Book of World Records for “the smallest man-made jet engine.”
Several attractive methodologies of machine-based functions at the micro- and nanoscale are shown. For instance, catalytic Ti/Cr/Pt microjets, which are integrated on a planar substrate, can operate as “on chip” chemical micropumps by decomposition of hydrogen peroxide fuel into oxygen bubbles and water. When released from a substrate, microjets self-propel autonomously in solution. The incorporation of ferromagnetic layer (Fe) into the rolled-up geometry enables their remote control using external magnetic field. Such microjets were used to load, transport, deliver and assemble multiple cargo particles, including biological cells in bulk solutions and microfluidic channels. Furthermore, it is demonstrated that for microjets that are fixed to or self-propelled above a platinum patterned surface, the microengine power/speed can be controlled using a white lightsource. A change in intensity of the white light leads to a controllable switching “off” and “on” of the microengine power on demand. Light degrades a local concentration of the hydrogen peroxide fuel and surface tension and subsequently suppresses the generation of oxygen microbubbles.
In the next step, the diameter of the microjets was rigorously reduced to 250 nm by using hybrid heteroepitaxial/catalytic InGaAs/GaAs/Cr/Pt nanotubes. Due to asymmetry of the rolled-up layers, these nanojets move in corkscrew-like motions and act as “self-propelled nanotools,” which were used in the next step to transport yeast cells and drill into fixed cancer Hela cells. Although it is well-known that hydrogen peroxide cannot be used to sustain viable cellular function, it is however conceivable that alternative fuels, such as glucose, might enable operation of such nanotools under biologically compatible conditions. As a first step to achieve this goal, demonstrations were made using metal-enzyme biocatalytic Ti/Au/SAM/Catalase microengines.
Synthetic components with competing interactions are well-suited to study the emergence of their collective behavior, such as swarms of large numbers of individuals. Microengines’ self-organization in bistable swarms is shown at the air-liquid interface of the mixture of propylene carbonate and hydrogen peroxide. Microengines act as “water striders.” Buoyed by oxygen bubbles, they self-propel via the microbubble recoiling mechanism and, depending on the bubbles’ sizes, self-organize into swarms due to the meniscus climbing effect. These reversible swarms depend on the microengine power, which competes against attracting surface tension force.
The demonstrated microjet engines show great promise for emerging applications, including biomedical, on-chip, environmental, and robotic micromachines. Furthermore, a key method discovered, entitled “rolled-up nanotechnology on polymers,” allowed for the fabrication of highly parallel arrays of microtubes with multiple functionalities and aimed for different purposes.
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Bernero, Stefano. "A turbulent jet in counterflow." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961718285.
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Nyblom, Per. "Designing a very light jet." Thesis, Mälardalen University, School of Innovation, Design and Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-4673.
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<p>Introduction</p><p><p>Very light jet is a hot subject growing stronger and stronger. The new type of air craft is an air plane that weighs less than 10000 pounds and uses a jet engine.</p><p>Problem</p><p>The student was proposed to designing a conceptual very light jet that could be used for inspiration and accepted the challenge.</p><p>Method</p><p>In this thesis the reader can follow the project progress in detail, the proposed methods and the results. The student divided the project into four activities analysis, creation, development and documentation.</p><p>Result</p><p>The project ended with a concept very light jet with simple specifications. Illustrations for inspirational usage and a simulation testing for verification of the proposed concept specifications.</p></p>
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Lowry, Christopher Graham. "Plasma-limiter interactions on JET." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392350.
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Joslin, Evelyn. "Jet spectroscopy of aromatic molecules." Thesis, Imperial College London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261303.
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Babaei, Lavasani Mohammad R. "Ink-jet printing of textiles." Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488155.
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Vasanthakumaran, R. "Jet dissipation in deep wells." Thesis, University of East London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261606.
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Heaphy, Eileen Anne. "Jet photoproduction and photon structure." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252008.
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Young, John Duncan. "Gas movement during jet ventilation." Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358708.
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Schild, Philippe. "Emission cyclotronique ionique sur jet." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37618473t.
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Tay, Bee Yen. "Continuous direct ink jet printing." Thesis, Queen Mary, University of London, 2001. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1560.
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This thesis describes the preparation and continuous printing of zirconia ink under different conditions, as well as the development of silver inks, for the same purpose. The dispersion of sub-micrometer zirconia powder in industrial methylated spirit using other additives such as dispersant and binder was investigated with different mixing methods and at varying powder and binder contents. The use of high shear mixing by triple roll milling followed by ultrasonic disruption as well as adequate sedimentation and filtration produced a homogeneous and stable ink of 2.5 vol. % ZrO2. The ink could be printed directly and continuously on a commercial jet printer without interruption of any kind and the phenomena occurring during printing were investigated. The optimum modulation frequency for printing was determined with the generation of pear-shaped and symmetrical droplets. Printing was made on substrates of surface free energies lower and higher than the surface tension of the Zr02 ink. Powder migration was observed within a relic of the printed dot on the second type of substrate. Layers were also overprinted on the second type of substrate by varying the following: print resolution, printing interval, print area, drying conditions and ink powder loading. These series of prints were accompanied by the appearance of ridges, spattering and non-vertical walls and the effects were investigated. The wettability and shrinkage of droplets of the ceramic ink was also studied in-situ by monitoring the evolution of contact angle, width of ink-substrate interface and droplet height with a video camera. The shape of the droplet experienced different dynamics on different types of substrate. Lastly, the sedimentation behaviour of ethanol-based silver inks dispersed with different types of dispersant was investigated with respect to the sediment volume and half-value time. Deflocculated ink was obtained at a low dispersant level and powder loading.
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Mitchell-Smith, Jonathon. "Advancing electrochemical jet machining techniques." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/54833/.
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Electrochemical Jet Processing (EJP) techniques have been traditionally limited in application by the inherent geometric inflexibility and limited process precision in comparison to alternative processes. It has been stated that process resultant geometries are defined by the Gaussian in-jet energy distribution and the hydrodynamic stagnation region formed under a jet on an impinging surface. This thesis reports upon investigations and innovations designed to challenge these assumptions. EJP is an emergent manufacturing process with a unique capability of subtraction and deposition of metals within a common machine tool. EJP demonstrates advantages beyond traditional electrochemical machining and electrochemical deposition including a high degree of flexibility, simplistic and therefore low-cost plant, requiring no complex, high-cost tooling and no masking requirement to achieve high fidelity geometries. These process traits are attractive to industry but EJP has yet to find significant commercial use. Electromechanical and electrochemical innovations are presented here demonstrated by electrochemical jet machining (EJM) the subtractive mode of EJP, which allow modulation of the properties of the inter-electrode gap leading to a paradigm shift in the functionality, precision and application of EJP. Electromechanical innovations demonstrate that the Gaussian energy distribution can be modified through the articulation of the jet angle of address and modified jet nozzles to manipulate the in-jet resistance. The outcome being the capability to produce bespoke removal profiles with increased precision and flexibility of form alongside refined surface finishes. Electrochemical innovations demonstrate an increase in precision through reducing overcut and reducing the feature shoulder radius when using a modified electrolyte. When these electromechanical and electrochemical innovations are coupled together, the overcut traditionally seen to be twice the nozzle diameter is reduced by 99%. Therefore, features can be created at kerfs approaching the nozzle diameter. Alongside this, a bespoke research platform has been built and developed to exploit these findings and incorporate features such as the rotational head for constant profiling and multiplexing of electrolytes to enhance the flexibility of the process. Process enhancements developed through this thesis have allowed the manipulation of the in-jet energy density profile and dissociation of the dissolution region from hydrodynamic phenomena thus allowing surface structuring by EJP to be developed well beyond the state-of-the-art.
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Elder, Benjamin T. (Benjamin Tyler). "Jet Fragmentation at the LHC." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119105.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 215-245).<br>Run II at the LHC is pushing the energy and luminosity frontiers, and challenging the theory community to develop new tools both to increase the precision of our predictions and to expand their scope to match measurements of a more diverse set of observables. In this work, we describe the use of a new class of non-perturbative functions called Generalized Fragmentation Functions (GFFs) as a step towards these goals. This theoretical framework enables the calculation of a broad set of semi-inclusive jet observables. We explore known observables whose distributions can now be calculated using GFFs, and construct a new class of non-associative "fractal observables" which can be described with GFFs. As an important application, we calculate the spectrum of track-assisted mass, which can be measured experimentally with much better angular resolution than ordinary jet mass, including the effect of Soft-Drop grooming. In order to make connections to frameworks for describing Quantum Chromodynamics, we discuss the relationship between GFFs and the Generating Functional Approach (GFA).<br>by Benjamin T. Elder.<br>Ph. D.
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Grover, Garth K. (Garth Kneeland) 1973. "Ink jet nozzle test station." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80504.
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Hall, Zachary (Zachary H. ). "Photon isolation and jet substructure." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120219.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 41-45).<br>We introduce soft drop isolation, a new photon isolation criterion inspired by jet substructure techniques. Soft drop isolation is collinear-safe and is equivalent to Frixione isolation at leading order in the small R limit. However, soft drop isolation has the interesting feature of being democratic, meaning that photons can be treated equivalently to hadrons for initial jet clustering. Taking advantage of this democratic property, we define an isolated photon subjet: a photon that is not isolated from its parent jet but is isolated within its parent subjet after soft drop declustering. The kinematics of this isolated photon subjet can be used to expose the QED splitting function, in which a quark radiates a photon, and we verify this behavior using both a parton shower generator and a perturbative calculation in the collinear limit.<br>by Zachary Hall.<br>S.B.
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Jouttenus, Teppo T. (Teppo Tapani). "Jet production at hadron colliders." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76979.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 101-104).<br>Hadronic jets feature in many final states of interest in modern collider experiments. They form a significant Standard Model background for many proposed new physics processes and also probe QCD interactions at several different scales. At high energies incoming protons produce beam jets. Correctly accounting for the beam and central jets is critical to precise understanding of hadronic final states at the Large Hadron Collider. We study jet cross sections as a function of the shape of both beam and central jets. This work focuses on measuring jet mass but our methods can be applied to other jet shape variables as well. Measuring jet mass introduces additional scales to the collision process and these scales produce large logarithms that need to be resummed. Factorizing the cross section into hard, jet, beam, and soft functions enables such resummation. We begin by studying jet production at e + e- collisions in order to focus on the effects of jet algorithms. These results can be carried over to the more complicated case of hadron collisions. We use the Sterman-Weinberg algorithm as a specific example and derive an expression for the quark jet function. Turning to hadron colliders, we show how the N-jettiness event shape divides phase space into N +2 regions, each containing one central or beam jet. Thus, N-jettiness works as a jet algorithm. Using a geometric measure gives central jets with circular boundaries. We then give a factorization theorem for the cross section fully differential in the mass of each jet, and compute the corresponding soft function at next-to-leading order (NLO). We use a method of hemisphere decomposition, which can also be applied to calculate N-jet soft functions defined with other jet algorithms. Our calculation of the N-jettiness soft function provides the final missing ingredient to extend NLO cross sections to resunmmed predictions at next-to-next-to-leading logarithmic order. We study the production of an exclusive jet together with a Standard Model Higgs boson. Based on theoretical reasons and agreement between our calculation and data from the ATLAS collaboration, we argue that our results for the jet mass spectrum are a good approximation also for inclusive jet production and other hard processes.<br>by Teppo T. Jouttenus.<br>Ph.D.
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Smith, Duncan Peter. "AGN jet-gas cloud interactions." Thesis, University of Bristol, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.761232.
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Greaves, Matthew. "Acoustic liners of jet engines." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/33817.
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Acoustic liners employing the Helmholtz resonator concept are commonly used in the intake duct of modern jet engines to reduce radiated noise. In response to reports of core failures, the possibility of acoustic loading as the source of these liner failures is investigated. Experimental data are used as input to a model for non-rigid cavity walls and the induced stresses analysed. An alternative, more robust, liner design utilizing viscous damping is proposed, and an analytical model developed and numerically validated against published data. A study of the key parameters leads to an improved configuration, the attenuating properties of which are compared to a typical liner.
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Webb, Stephen David. "Jet impingement on porous surfaces." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/47117/.
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A series of experiments are described, documenting the flow resulting from the normal impingement of planar and axisymmetric jets onto a porous surface. Six different porous surfaces with open area ratios of 23, 26, 31, 37, 44 and 54% (β = 0.23, 0.26, 0.31, 0.37, 0.44 and 0.54) were placed in low speed (usually 40m/s exit velocity) air jets sufficiently far from the jet exit for the jet to be self similar. The β=0.31, 0.37, 0.44 and 0.54 surfaces were wove wire mesh. Exit Reynolds number based on jet exit diameter is 3x104 for the axisymmetric case and based on exit width from 0.5x104 to 2.1x104 for the planar case. For β=0.44 and β=0.54 the impingement of the jet for both planar and axisymmetric geometries can be summarised as a widening of the jet as it passes through the mesh, followed by a region of reduced entrainment. For β=0.37 and below, there is evidence of wall jets on the upstream side of the surface. For the β=0.31 mesh and β=0.26 perforated plate, there are marked differences between the axisymmetric and planar cases. For the planar cases the flow is turned downstream of the porous surface away from the centreline such that on the centreline the axial velocity falls to zero, whilst a clear jet remains in the axisymmetric cases. Downstream of the β=0.23 porous surface there is a clear bounded jet in both planar and axisymmetric cases. The presence of a counter-flow at some distance from the centreline, downstream of the surface inhibits entrainment into the downstream jet; its growth rate and velocity decay rate are reduced
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Powling, Alexander. "Jet substructure : an analytical approach." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/jet-substructure-an-analytical-approach(e1e67bdc-ddda-41e6-a263-af9c0836f278).html.
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In the past few years, detailed study of the internal structure of hadronic jets has become an active area of research. In particular, jet substructure information has been used to distinguish signal from QCD initiated jets, which constitute a significant background for many physics searches. Prior to the work undertaken in this thesis, theoretical research on jet substructure was largely Monte Carlo based, with limited analytical input. This work presents an analytical approach to the study of jet substructure techniques in the context of high-p_T heavy resonance searches at the LHC.In this thesis, we compute the mass distribution of QCD initiated jets after application of several jet substructure algorithms using approximate fixed-order perturbative QCD at leading and next-to-leading order. This is sufficient to extract the leading logarithmic structure for each technique, which we compare to exact fixed-order results. Using this analytical insight, we propose modifications to some of these algorithms and use our results to discuss the phenomenological impact of different parameter choices. We also perform analytical calculations and Monte Carlo studies to examine the impact of QCD radiation on jets that arise from boosted Higgs decay after application of several jet substructure algorithms. Understanding the action on signal jets is important when two techniques perform similarly on background jets. An example studied here is the Y-splitter and Y-pruning techniques, which both perform well at rejecting background; however, the former retains signal jets which are subject to significant radiative and non-perturbative corrections. We demonstrate that the combination of Y-splitter with trimming ameliorates the poor signal tagging efficiency of Y-splitter whilst retaining effective background rejection. Consequently, we find that this combination outperforms the other techniques studied here, at high p_T. We use our analytical expressions to perform an approximate optimisation of parameters for each algorithm and compare our results to Monte Carlo simulation. Finally, we undertake an analytical fixed-order and resummed study of the mass distribution for QCD jets for the combination of Y-splitter with trimming. We demonstrate that the trimming has a numerically subleading effect on the Y-splitter distribution for typical parameter choices and discuss why such techniques can prove to be superior when compared to the currently proposed individual methods.
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Williams, John Charles. "Water ingestion in jet engines." Thesis, University of Cambridge, 2003. https://www.repository.cam.ac.uk/handle/1810/265455.
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Civil aircraft engines are required to operate reliably in a variety of inclement weather situations. Ingestion of airborne water has been found to cause problems for certain engine types, particularly during aircraft descent at low engine power settings. The effects of water ingestion under these engine operating conditions are not well understood. It is believed that the engine pe1formance is largely dete1mined by the behaviour of liquid water in the core compression system. A programme of experimental and theoretical research has therefore been undertaken to investigate the effects of water ingestion on an axial flow compressor operating at low speed, in isolation from other engine components. Experimental studies have been conducted using a low-speed, four-stage axial flow laboratory compressor, modified to facilitate injection of water through spray nozzles fitted at the inlet. In the process, new methods were developed for the reliable measurement of static pressure in a wet environment. Compressor pe1formance changes were quantified by measming the overall total-to-static pressure-rise characteristic and the torque requirement. Initiation of water ingestion was shown to move the compressor operating point on the characteristic to a new position at reduced pressure rise and reduced air mass flowrate, and to increase significantly the torque requirement. In some cases, it was shown that initiation of water ingestion would lead to rotating stall. Experiments were conducted to investigate the effects of water-to-air mass flowrate ratio, droplet size and spray coverage. The spray coverage is the fraction of the compressor inlet area over which the water is distributed. This was determined principally by the divergence (or spray) angle of the water emerging from each nozzle. The results suggest that droplet size is relatively unimportant in determining the performance with water ingestion. The spray coverage is, however, important, with small spray coverage resulting in little or no loss of compressor surge margin and large spray coverage resulting in significant loss. The pe1formance of the first compressor stage is c1itical in explaining these differences in behaviour. Theoretical studies were conducted with the aim of predicting the spatial disttibution of liquid water inside a compressor. New models were developed for key aspects of liquid water behaviour and incorporated into a computer program. Droplet velocity (or momentum) is often found to play an important role in determining the water behaviour. Theories are suggested to explain the experimentally observed effects of water ingestion, drawing on insight gained from both the expe1imental and theoretical results. Compressor modifications that may reduce the adverse effects of water ingestion are then suggested. These comprise, firstly, the removal of water from the casing immediately upstream of the compressor and, secondly, the application of a "non-stick" coating to the blades of the first rotor blade row.
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Wickramasinghe, G. L. D. "Steam-jet intermingled sewing threads." Thesis, University of Manchester, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.601663.
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The object of the work was to develop the use of high-pressure steam in order to replace air in air-jets in the production of intermingled yarns, particularly for sewmg threads. The thesis discusses the development of air-jet texturing! intermingling and analysis of the process by earlier workers. Differences between steam-flow and air-flow through jets are discussed. The effects of process parameters on steam-jet intermingling and comparisons of steam-jet intermingled yarns and air-jet intermingled yarns have been studied. The results show that steam-jet intermingled yarn has higher strength, higher elongation, higher loop stability and lower boiling water shrinkage than air-jet intermingled yarn. Core-yarn wetting does not have a significant effect on the steam-jet intermingling process and intermingled yarn properties. Elimination of the wetting system reduces the production cost of steam-jet compared to air-jet. Steam-jet intermingled yarn needs less energy to heat-set after intermingling, as it has been partially heat-set by steam during intermingling. Sewing threads were made from steam-jet intermingled yarns and assessed using industrial sewing specifications. The sewing threads were also subjected to commercial trials. Sewing test results show that steam-jet intermingled sewing thread meets commercial levels of performance. Preliminary investigations revealed that high-pressure water could also be used in intermingling as a replacement of air or steam. It was found that lower core-yarn overfeeds, such as 2.9 %, can be used and therefore higher strength of intermingled yarn could be achieved. Turbulence in water was improved by designing a jet so as to suck air by water through a capillary from the outside atmosphere.
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Pundarika, G. "Experimental And Theoretical Studies On Jet Acoustics." Thesis, Indian Institute of Science, 2001. http://hdl.handle.net/2005/250.
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A systematic research on aeroacoustics conducted around the world for the last few decades has revealed various inherent characteristics of the jet noise radiation. However, a lot more needs to be done for the theoretical as well as experimental predictions of various jet noise features based on actual flow details. The work reported in the present thesis is an attempt in this direction.
A critical study of existing literature on jet noise shows that none of the general wave equations lends itself easily for predictions of all the jet noise features. It is shown that while LighthilPs classical acoustic analogy approach, with some reasonable approximations, can be used to yield most of the information needed by the engineers, the convected wave equations of Phillips and Lilley are required to study the acoustic radiation in what has come to be known as "Refraction valley" or "Cone of relative silence".
The characteristics of the sound field of underexpanded cold jet impingement flows were studied by measuring the noise emanating from two convergent nozzles of throat diameter 2.5 mm and 5 mm each and a convergent - divergent nozzle of exit diameter of 6.49 mm, when the jet impinges on a flat plate kept perpendicular to the direction of the jet. The measurements were conducted upstream of the nozzle over an extensive envelope of jet operating conditions such as chamber stagnation pressure, mass flow rate through the nozzle and diameter of the nozzle.
The source strength at the jet boundary was obtained by measuring acoustic pressure amplitude close to the jet contour assuming it as locally cylindrical. Particular attention was focussed on backward projection of the sound field on to a cylindrical surface. This is the application of acoustic holography to study the sound radiation in the audio frequency region. With the help of FFT and software developed for this purpose, the theoretical predictions using data from several cylindrical surfaces were compared.
A detailed analysis of noise radiation from a cold sonic and supersonic free jet was also carried out. The experimental work involved the measurement of noise field from a 2.5 mm, 5 mm convergent and a convergent - divergent nozzle of exit diameter of 6.49 mm and area ratio 1.687 for designed Mach number of two.
The experimental setup consisted essentially of a pressure chamber made of mild steel, designed to withstand 50 bar pressure. This chamber is a cylinder with dia 0.421 m and length 0.85 m. The nozzles were made of mild steel. Compressed air approximately at room temperature is supplied to the nozzle via a control valve.
The measuring and recording instruments consists of B & K Microphones, Preamplifiers, Conditioning amplifier and a Mediator, which measure a Sound Pressure Level at a point. The nozzles were operated at pressure ratio upto 25 bar. The noise signal was processed through 12 channel data acquisition system. Acoustic pressure and SPL were" calculated using theoretical relations and software developed. Using this software Fast Fourier Transformations of raw signal was obtained from 20 Hz to 20 kHz. Also constant SPL contour graphs were obtained.
Source strength distribution at the jet boundary has been obtained by the principle of acoustic holography. Experimental values are closely matching with the results obtained by acoustic holography. The percentage error for acoustic pressure and SPL were less than 12%. The experimental results were used to obtain the source distribution in terms of gross jet parameters.
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Rohaly, Matthew Joseph. "Decomposition of Aromatic Amines in a Jet Fuel Surrogate." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1417777531.
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