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Williams, Adrian Michael. "Thermal Vacuum Chamber Refurbishment and Analysis." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1860.
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Spacecraft are subject to different environments while on orbit around the Earth and beyond. One of the most critical of these environments that must be counteracted is the thermal environment. Each spacecraft has an operating temperature that is specified in the mission requirements. The requirement stems from internal component operating temperatures that are critical to mission success. Prior to placing the spacecraft in orbit, engineers must be sure that the spacecraft will survive or risk losing the mission entirely.
The primary way to mitigate this risk is to use a thermal vacuum chamber (TVAC). The chamber is designed to resemble a space environment by reducing the pressure within the chamber to 1e-6 Torr. The differentiating factor between a vacuum chamber and a thermal vacuum chamber is the ability for the TVAC to complete a process known as thermal cycling using a temperature controller. Thermal cycling begins at a set temperature and increases within the chamber to a designated hot temperature expected to be seen on orbit. After the maximum temperature is reached, it remains there for a specified amount of time in what is called a soak. The controller then reduces the temperature to a specified cold temperature where a second soak takes place. Finally, the temperature is returned to the initial temperature and the process is repeated for a number of cycles until testing is complete.
For the purpose of this thesis, only the initial temperature increase and the first soak are being investigated. The chamber being used to run these experiments was graciously donated by MDA US Systems, however, no additional documentation was provided with the chamber. The Two identical black coated aluminum and brass cylinders have been chosen to be run with three different temperature profiles. The profiles are manually designed in the temperature controller on the chamber and vary by final soak temperature. To supplement the testing, simulations have been created for each test case in order to verify the computer model of the chamber. The simulations utilize AutoCad and Thermal Desktop to provide the results for comparison.
Each of the tests were completed successfully and produced good results that corresponded well to the simulation. The largest difference between the simulation cylinder temperature and the experimental cylinder temperature was 1.9 $^{\circ}$C. The effectiveness and efficiency of the blue chamber was compared to the other thermal vacuum chamber in the Space Environments lab. Overall, the Blue Chamber proved to be more robust and much easier to operate than the HVEC thermal vacuum chamber.
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Brown, P., J. Silvertooth, and J. Malcuit. "Evaluation of the Pressure Chamber for Timing Early Season Irrigations." College of Agriculture, University of Arizona (Tucson, AZ), 1993. http://hdl.handle.net/10150/209564.
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Use of the pressure chamber to time the initial post- planting irrigation of short season upland cotton was evaluated in a pilot study at Marana during 1992. Top yields and better overall plant performance were obtained when the initial post - planting irrigation was applied before leaf xylem potential (ψx) dropped significantly below -15 bars. Our findings were similar to those previously observed with Acala cotton in California. The authors believe more work is required before use of the pressure chamber is recommended for irrigation management in Arizona. Specifically, an effective means of separating changes in ψx resulting from day-to-day climate fluctuations from those caused by soil-water depletion must be developed. This study also clearly showed the importance of avoiding early season water stress when growing short season cotton.
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Zhong, Chong. "Pressure Chamber Experiments to Determine Triaxial Material Properties of Polymer Foams." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1556265641540063.
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McGlashan, Niall Ross. "Design and testing of a high pressure chamber for diesel spray studies." Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/7174.
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Ravi, Vinay. "Effect of nonlinear chamber compliance and pumping areas on the dynamic stiffness and chamber pressure of a hydraulic body mount." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1532032639331273.
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Pal, Aniruddha. "Experimental and Numerical Study of Dual-Chamber Thermosyphon." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16251.
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An experimental and numerical investigation was conducted to study boiling and condensation - the two most important phenomena occurring in a dual-chamber thermosyphon. Boiling experiments were carried out using water at sub-atmospheric pressures of 9.7, 15 and 21 kPa with a three-dimensional porous boiling enhancement structure integrated in the evaporator. Sub-atmospheric pressure boiling achieved heat fluxes in excess of 100 W/cm2 with negligible incipience superheat, for wall temperatures below 85 oC. Reduced pressures resulted in reduction of heat transfer coefficient with decrease in saturation pressure. The boiling enhancement structure showed considerable heat transfer enhancement compared to boiling from plain surface. Increased height of the structure decreased the heat transfer coefficient and suggested the existence of an optimum structure height for a particular saturation pressure. A parametric study showed that a reduction in liquid level of water increased the CHF for boiling with plain surfaces. For boiling with enhanced structures, the liquid level for optimum heat transfer increased with increasing height of the enhanced structure.
A numerical model was developed to study condensation of water in horizontal rectangular microchannels of hydraulic diameters 150-375 µm. The model incorporated surface tension, axial pressure gradient, liquid film curvature, liquid film thermal resistance, gravity and interfacial shear stress, and implemented successive solution of mass, momentum and energy balance equations for both liquid and vapor phases. Rectangular microchannels achieved significantly higher heat transfer coefficient compared to a circular channel of similar hydraulic diameter. Increasing the inlet mass flow rate resulted in a higher heat transfer coefficient. Increasing the inlet temperature difference between wall and vapor led to a thicker film and a gradually decreasing heat transfer coefficient. Increasing the channel dimensions led to higher heat transfer coefficient, with a reduction in the vapor pressure drop along the axial direction of the channel.
The unique contributions of the study are: extending the knowledge base and contributing unique results on the thermal performance of thermosyphons, and development of a analytical model of condensation in rectangular microchannels, which identified the system parameters that affects the flow and thermal performance during condensation.
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Choi, Yong Seok. "Diesel spray characterisation in a high pressure chamber and in a single-cylinder engine." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393885.
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Mishra, Neeraj Kumar Ratner Albert. "Effect of chamber pressure on liquid drop impacts on a stationary smooth and dry surface." [Iowa City, Iowa] : University of Iowa, 2009. http://ir.uiowa.edu/etd/408.
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Junaideen, Sainulabdeen Mohamed. "The design and performance of a pressure chamber for testing soil nails in loose fill." Thesis, Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23273331.
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Mishra, Neeraj Kumar. "Effect of chamber pressure on liquid drop impacts on a stationary smooth and dry surface." Thesis, University of Iowa, 2009. https://ir.uiowa.edu/etd/408.
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Impact of drops on a dry smooth surface was studied at elevated chamber pressures and low Reynold's numbers to characterize the effect of chamber pressure on drop splashing and spreading. Two drop sizes of methanol, ethanol, propanol, hexadecane and diesel were tested for impact speeds between 1.5 - 3.3 m/s and pressure of upto 12 bars. Splash ratio, unlike the results of Xu et al, increased sharply with decreasing impact speed suggesting that drop speed is a more critical parameter for splash. Drop splashing was also found to be affected by drop shape, with drop distortion having a significant impact on splash promotion or suppression. In accordance with existing theory, drop spreading and maximum spread factor were found to be independent of pressure in the regime tested. These observations provide new insights and comparison data for evaluating and modeling the behavior of alternate fuels like ethanol.
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Fischer, Warren P. "Design and qualification of a high-pressure combustion chamber for ignition delay testing of diesel fuels." Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34662.
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Approved for public release; distribution is unlimitedA high pressure and temperature combustion chamber was designed to compare the ignition properties of different fuels, including conventional F76 diesel and hydrotreated renewable diesel (HRD), derived from algae. Conditions were selected to capture the operating conditions within a large number of Navy systems, testing at a range of temperatures from 8001340 F and pressures as high as 20 atm. Three Navy-relevant injectors were procured for the testing as well as a commercial injector made by Sturman Industries. The Sturman diesel injector was characterized up to a fuel tip pressure of 9600 psi and produced Sauter Mean Diameters of approximately 90 microns, generally showing improved atomization for F-76 when compared to HRD at similar conditions. The combustion chamber utilized dynamic air injection with increased turbulence and the ability to alter the amounts of combustion products including CO, CO2 and H2O that typically exist in real engines from the previous combustion event. Qualification testing of the combustion chamber evaluated final pressures of up to 15 atmospheres and temperatures of 472 F, but revealed heat losses during the dynamic air injection events, resulting in temperatures below expected values and auto-ignition conditions for fuels under consideration. A fluidized bed heat exchanger will be implemented to supplement the existing design and reach the desired temperatures.
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Himango, Stephanie V. "The American Chamber of Commerce (Hong Kong) : an analysis of a dual purpose business and political organization /." Thesis, Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18061898.
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Eissa, A.-F. M. M. "Experimental investigation of spontaneous ignition of individual moving fuel/bipropellant droplets at different levels of chamber pressure." Thesis, Cranfield University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374143.
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Raber, Erica Candace. "SPATIAL RESOLUTION CHARACTERIZATION OF IMAGES TAKEN FROM A CAPILLARY-BASED HIGH PRESSURE CHAMBER FOR BIOLOGICAL IMAGING STUDIES." Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1154702307.
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GIKUNDA, MILLICENT NKIROTE. "An improved sample loading technique for cellular metabolic response monitoring under pressure." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1470194454.
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Stonell, G. P. "The track structure of protons and other radiations in pure water vapour measured in a low pressure cloud chamber." Thesis, University of Westminster, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373002.
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Olsson, Mikael, and Anders Söderberg. "Design guideline for audible warning signal and determination of sound pressure characteristics : Second version." Thesis, Örebro universitet, Akademin för naturvetenskap och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-19412.
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Today Atlas Copco Rock Drills AB hasn’t got any method to determine how many warning alarms they need on their machines and how they should be mounted to use their full potential. At the moment a travel alarm is usually placed in the front of the machine and a reverse alarm in the back. Then a measurement of the sound pressure level around the machine is performed to see if it is enough to pass the limit according to different ISO-standards. Otherwise they have to mount some extra alarms and then do the measurements again until the standards are fulfilled. The aim of this thesis work is to develop a method for determine how many alarms Atlas Copco Rock Drills AB need on the machines, and also how they should be mounted to fulfil the different criteria according to ISO-standards in the early phase of construction. From the different divisions within Atlas Copco Rock Drills AB (LHD, SDE and TME) arrived four different alarms, which are used on their machines. Sound pressure level measurements were conducted on these, in the anechoic chamber at audiological research centre at the university hospital in Örebro. In the LMS Test.Lab software a measurement sphere was built around the horns and based on the data obtained at the anechoic chamber sound directivity plots were made. Together with earlier machine measurement data from Atlas Copco Rock Drills AB, an Excel program was made constituting an example of how the horns should be mounted. LHD = Loaders and trucks/underground rock excavation SDE = Surface drilling equipment TME = Tunnelling and mining equipmentIdag har Atlas Copco Rock Drills AB inte någon metod för att bestämma hur många varningsalarm som behövs på sina maskiner samt var de ska placeras så de utnyttjar sin fulla potential. I nuläget monteras ett signalhorn vid främre delen och ett backlarm i bakre delen av maskinen. Sedan utförs en ljudtrycksmätning runt maskinen för att kontrollera om man uppfyller kraven från olika ISO-standader. Annars monteras fler alarm och mätningen utförs på nytt tills standarderna uppfylls. Detta examensarbete har som mål att ta fram en metod som bestämmer hur många alarm Atlas Copco Rock Drills AB behöver på sina maskiner, samt hur de skall placeras för att uppfylla kriterierna från olika ISO-standarder redan i konstruktionsstadiet. Från de olika avdelningarna inom Atlas Copco Rock Drills AB (LHD, SDE och TME) mottogs fyra olika alarm, som används på maskinerna. På dessa utfördes ljudtrycksmätningar i det ekofria rummet vid audiologiskt forskningscentrum på universitetssjukhuset i Örebro. I programmet LMS Test.Lab byggdes en sfär av mätpunkter runt alarmen och baserat på insamlade data från det ekofria rummet konstruerades direktivitetsdiagram. Tillsammans med data som Atlas Copco Rock Drills AB redan hade från tidigare mätningar på maskiner gjordes ett Excel-program, som ger ett exempel på hur alarmen bör monteras. LHD = Loaders and trucks/underground rock excavation SDE = Surface drilling equipment TME = Tunnelling and mining equipment
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Aye, Maung Maung [Verfasser]. "Spray Combustion of Single- and Multi-component Fuels under Engine-like Conditions in a High Pressure Chamber / Maung Maung Aye." Aachen : Shaker, 2015. http://d-nb.info/1070152005/34.
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Zayas, Evan M. "An analysis of the sensitivity of a low pressure time projection chamber to a directional anisotropy due to WIMP interactions." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100322.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-60).
The Dark Matter Time Projection Chamber (DMTPC) collaboration is a dark matter direct detection effort which develops TPCs to observe and reconstruct nuclear recoils generated by incident particles. If some of these recoils are the result of dark matter interactions, we can in theory observe an anisotropy in the direction of these recoils which is consistent with the galactic halo models of dark matter. Such an observation would serve as convincing evidence that these incident particles have an extrasolar origin. In this thesis I discuss the workings of a TPC known as the 4-shooter, the analysis used to identify nuclear recoil candidates, and the mathematics to quantify the anisotropy of a distribution. I then discuss the ways in which the pressure of the target gas in the TPC affects rejection power, and construct a framework to determine an optimal operating pressure for the 4-shooter and future DMTPC detectors.
by Evan M. Zayas.
S.B.
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Henderson, Shawn Wesley. "An assessment of the sensitivity of a low pressure time projection chamber to the direction of WIMP-induced nuclear recoils/." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84395.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 207-219).
Direct directional detection of dark matter could provide an unambiguous observation of dark matter due to the predicted directional anisotropy of dark matter particles in the galactic reference frame. The Dark Matter Time Projection Chamber (DMTPC) collaboration develops TPCs with optical readout whose goal is the detection of the sense and direction of nuclear recoils generated by dark matter interactions with carbon and fluorine atoms in low pressure CF 4 gas, from which the direction of the incident dark matter particle can be inferred. The TPC contains a mesh based amplification stage that facilitates the two-dimensional imaging of nuclear recoil tracks using CCD cameras. Reconstructing the direction of recoils has been a subject of intensive R&D over the past several years, culminating in the design and construction of a current generation detector, the "4-shooter." The 4-shooter is prototyping several new detector techniques for a larger (1 m3 ) detector. The third dimension of recoils will be reconstructed in this detector using PMTs and the timing of induced charge signals in the detector amplification region. The 4-shooter's performance has being studied extensively on the surface of the Earth at MIT using alpha particles, low energy neutrons, and X-rays. This thesis reports on surface commissioning data taken with the 4-shooter.
by Shawn Wesley Henderson.
Ph.D.
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Šabacká, Pavla. "Analýza nadzvukového proudění v experimentální komoře při vložení tlakových a teplotních sond." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413029.
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For the supersonic flow mode, which occurs in the internal flow behind the aperture separating two spaces with a large pressure drop, the critical flow is a characteristic phenomenon. In the case of critical flow behind the aperture, a supersonic flow area with reduced pressure ending with a shock wave with a step change in state variables is created. When diagnosing velocities, which are obtained from the values of static and total pressure, due to the changes caused by the shock wave passage, correction of the diagnostic quantities obtained by measuring by means of mathematical relations taking into account the physical phenomena is necessary.
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Mardanova, Elvira. "Srovnávací analýza proudění plynu clonou v nízkých tlacích pomocí mechaniky kontinua s metodou Monte Carlo." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442557.
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This thesis is based on the series of scholarly article dedicated to the issue ofpumping in the differential scanning chamber of an environmental scanning microscope. The thesis is based on Danilatos’s study where the pumping of the differential pumped chamber is solved by means of the Monte Carlo statistical method. The thesis performs analysis of gas flow at low pressures through orifice separating the spaces with a large pressure drop Dr. Danilate. The analyses will be used for the design of the experimental chamber which will serve for the experimental evaluation of the flow results in the chamber using the continuum mechanics.
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Mostofa, Md Golam. "Base material characterisation of spoil piles at BMA coal mines." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/90717/4/Md_Golam_Mostofa_Thesis.pdf.
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This project was an initiation to investigate slaking induced properties detrition of spoil pile materials with overburden pressure and time. The changes in the material properties over time are important parameters that control the behaviour and performance of the piles. The time dependent mechanical and hydraulic properties reported together with mineralogical changes. One chamber designed to apply slaking in the laboratory and geotechnical investigation conducted to fulfil the objective of this project.
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Pan, Sheng. "Development of a high pressure xenon gas time projection chamber with a unique cellular readout structure to search for neutrinoless double beta decay." Kyoto University, 2020. http://hdl.handle.net/2433/253472.
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Orita, Naho. "Root uptake of organic contaminants into plants: Species differences." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1287.
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Trace amounts of xenobiotic organic contaminants have been frequently identified in the environment, including surface water and wastewater streams, and some are even in drinking water. The concern of unintended ingestion by humans or wildlife of such compounds resulting from the uptake by plants has risen in recent years. Although the uptake of a variety of xenobiotic organic contaminants by plants has been reported and the contaminants are found in the fruits in some cases, the differences between plant species are not fully understood. The emphasis of this research is to investigate the unique uptake ability of zucchini that has been reported repeatedly in recent years. Xylem saps, collected using a pressure chamber technique, were used to determine the values of Transpiration Stream Concentration Factor (TSCF), the ratio of the contaminant concentration in the xylem to that in the solution. Soybean "hoyt," squash "zephyr," and zucchini "gold rush" were used to compare the uptake ability of each plant. The root tissue was analyzed for total carbon and lipid content. Xylem sap was analyzed for total organic carbon and protein contents. The solubilities of the compounds in the xylem sap and deionized water were also determined using a modified shake flask method. From the measurement of TSCF, the uptake of hydrophobic contaminants in zucchini "gold rush" was found to be three-to tenfold of the other two plant species. The lipid content of the root tissue from zucchini "gold rush" was twice as much of that in soybean and squash "zephyr," indicating enhanced adsorption of the hydrophobic compounds. The solubility of triclocarban in the xylem sap of zucchini "gold rush" was also twice the amount of that in soybean xylem sap. The enhanced solubility could be a result of high protein content measured in zucchini "gold rush" xylem sap, which may be increasing the facilitated transport of the hydrophobic compounds. The data generated in this study will be used to better understand the mechanistic differences associated with the plant uptake of organic contaminants by different species. This information can also be used in the selection of the plant species used in risk assessment studies and phytoremediation studies.
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Jones, Tony Lee. "Interaction of liquid droplets with low-temperature, low-pressure plasma." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-04072005-144736/.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2005.Said I. Abdel-Khalik, Committee Chair ; Sheldon M. Jeter, Committee Member ; Minami Yoda, Committee Member. Includes bibliographical references.
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Nevrzal, Filip. "Stanovení tlakových poměrů ve zhášecí komoře nízkonapěťového přístroje." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-399559.
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In this master’s thesis there is firstly conducted research about pressure measurement. Next there is mathematical description of thermodynamic conditions in used testing chamber by using magnetohydrodynamic and Maxwell equations. Next chapter deals with testing chamber itself, more precisely with function, model and changes done to it. In practical part there are data measured by used sensors, which are also closer described in this chapter. In next chapter there is comparison of reaction times of used sensors and their frequency specters, obtaining using fast Fourier transformation. Second to last chapter introduces very measurement on the real device and in the last chapter these data are analyzed and more closely described.
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Szegedi, Peter. "Výroba tepla a elektrické energie ve spalovně směsného komunálního odpadu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230117.
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This diploma thesis deals with a design of steam boiler used to incineration of mixed municipal waste. Based on the specified fuel and the required output parameters of the steam from a steam boiler is calculated stoichiometry of incineration, thermal losses and overall boiler efficiency. Other chapters of thesis are focused on construction and thermal calculation of boiler moves. Finally, this thesis is to check heat balance of the boiler.
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Andriamasinoro, Vakana Miaina. "Territoire et répertoire du lobbying patronal : le cas des Chambres de commerce et d'industrie en Rhône-Alpes." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENH019/document.
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"Le pouvoir n'est rien, seule compte l'influence". Cette pensée du philosophe grec Hérodote constitue le points de départ et le fil conducteur de la présente recherche. Elle pose l'idée de l'influence qui fait partie intégrante du processus décisionnel. La décision politique contemporaine obéit à ce même principe, celui d'un pouvoir qui ne peut plus décider seul, sans concertation, sans choisir de subir la pression des lobbies de toute nature qui se constituent à l'occasion d'une décision (Giuliani, 1991). Le lobbying, en tant qu'activité d'influence, apparaît alors comme un phénomène indissociable de la décision publique. Pour déterminer l'État, il faut alors prendre en considération les « rapports de forces mouvants » (Culpepper et al., 2006) qui y existent. En France, lobbying et groupes d'intérêt connaissent un discrédit qui tend à ignorer le rôle qu'ils peuvent jouer dans les politiques publiques. Les Chambres de commerce et d'industrie font partie de ces groupes qui restent méconnus malgré leur mission de représentation de l'intérêt économique des entreprises. Il est alors intéressant de rendre compte de ce lobbying dans le contexte français à travers l'usage qu'en font les Chambres de commerce et d'industrie. La recherche représente un double intérêt : celui d'étudier un acteur de politique publique original et le répertoire d'action qu'il mobilise pour tenter d'influer sur la décision publique. Ainsi, si Robert Dahl s'interrogeait de savoir « qui gouverne » (1961), il nous apparaît important de nous demander aussi : « comment gouverner » et « avec qui gouverner » aujourd'hui ? Notre recherche vise alors à répondre à la problématique : dans quelle mesure un groupe d'intérêt peut-il concrètement agir sur le processus de politique publique ? Ainsi, pourrons-nous analyser ce que le groupe, notamment ses moyens d'action, enseignent sur le fonctionnement de l'action publique contemporaine, car comme l'avait affirmé Arthur Bentley dès 1908 dans son célèbre ouvrage The process of government : A study of social pressure : « Quand le groupe est expliqué, tout est expliqué »As Greek philosopher said: "Power is nothing, influence only countsé". This is the starting point and the thread of this research. It puts down the idea of influence, which is an integral part of the decision-making. The contemporary political decision obeys the same principle, that of a power who cannot decide alone, without consultation, without choosing to undergo the pressure of lobbies of all kinds that are formed in the occasion of a decision (Giuliani, 1991). The lobbying, as an activity of influence, appears then as an inseparable phenomenon of the public decision. In order to determine the State, it is therefore necessary to take into account the "unstable balance of power" (Culpepper et al., 2006) that exists there. In France, lobbying and interest groups are experiencing a discredit which tends to ignore the role that they can play in the public policies. The Chambers of commerce and industry are part of those groups that remain unknown despite their task of representing the economic interests of companies. It is therefore interesting to report this type of French lobbying through the use made from the Chambers of commerce and industry. Our research presents a double interest: to study an original actor of public policy and also the directory of action which he mobilizes in order to try to influence the public decision. So, if Robert Dahl questioned in 1961 about "who governs", it seems important nowadays to wonder about: "how to govern" and "with who"? Our research aims then to answer the following question: to what extent an interest group can concretely act on the public policy process and what does it teach us about the functioning of the contemporary public action? Thus, we can analyze what the group, and in particular its means of action, can teach us about the functioning of the contemporary public action, because as noted by Arthur Bentley, in 1908, in his famous book entitled The process of government: A study of social pressure: “When group is explained, everything is explained”
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Vitula, Michal. "parní kotel na dřevo výkonu 50t/h." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230144.
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Steam boiler for wood burning 50t/h In this diploma thesis I will deal design of the steam grate boiler 50t/h of burning clean wood. For the specified parameters make a stoichiometric calculations and calculate the enthalpy of the air and combustion. I shall calculate the heat balance, losses of boiler and thermal efficiency of the boiler. The following section make a design of the combustion chamber and its thermal calculation. After determining the dimensions of the combustion chamber further continue by calculating boiler moves and heating surfaces. Finally check the overall heat balance.
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Wallace, William, and Oskar Wiström. "Utveckling och tillverkning av flödestestkammare med högupplöst motstånd för kompaktfläktar : Mätinstrument som mäter statiskt tryck och luftflöde för framställning av fläktkurvor vid prestandamätning av kompaktfläktar." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-179130.
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Examensarbetet har utförts hos RotoSub AB i Linköping. RotoSub fokuserar på innovativa lösningar inom brusreducering för fläktar och är även utvecklingspartner med det österrikiska företaget Noctua, som utvecklar och tillverkar kompaktfläktar och processorkylare inom elektronikbranschen. Under examensarbetet har en flödestestkammare för kompaktfläktar utvecklats och tillverkats. Testkammaren utnyttjar ett högupplöst motstånd som ger möjlighet till ett flertal driftpunkter för att konstruera detaljerade fläktkurvor. Detta låter RotoSub noggrant analysera och undersöka fläktkaraktäristiken under utvecklingsstadiet. I rapporten undersöks två metoder för att bestämma luftflödet genom testkammaren. Däribland en känd geometri i form av munstycken, enligt den amerikanska standarden ANSI/AMCA 210-16 samt utnyttjandet av en varmtrådsanemometer. Vidare undersöks alternativ för att konstruera ett högupplöst motstånd med hög pålitlighet och repeterbarhet, samt en tryckmätningsmetod som tillåter en jämn avläsning av det statiskatrycket som testfläkten ger upphov till. Under utvecklingen tillverkades prototyper där koncept testades och utvärderades, innan slutprodukten kunde modelleras i ett CAD-program för att slutligen tillverkas fysiskt. Slutprodukten tillverkades huvudsakligen i styren-akrylnitril (SAN) samt ett fåtal komponenter i polylaktid (PLA) och aluminium. Testkammaren använder sig av en tryckring med fyra tryckportar, en varmtrådsanemometer för att mäta luftflödet samt en roterande skiva som drivs av en stegmotor för att högupplöst variera motståndet i testkammaren. Testkammaren har visat sig kapabel att konstruera fläktkurvor för samtliga fläktstorlekar undersökta under arbetet med god repeterbarhet. Vidare arbete finns gällande tätning, då ett visst läckage finns i testkammaren vilket ger ett systematiskt fel i fläktkurvorna vid låga flöden där maximalt statiskt tryck inte kan uppnås.This undergraduate thesis has been carried out at RotoSub AB in Linköping, Sweden. RotoSub develop innovative solutions for noise-reduction in fans. RotoSub are also development partners to the Austrian company Noctua, who design and develop fans and processor coolers for the electronics industry. During the thesis a compact airflow test chamber has been designed and constructed. The test chamber utilises a high-resolution load to measure and create a fan curve. The high-resolution load ensures that a large amount of operating points can be measured, which gives RotoSub the opportunity to closely analyse the characteristics of the fan being tested. In this thesis two different methods of measuring the airflow through the test chamber have been studied. Firstly a method of using nozzles to calculate the flow according to the standard ANSI/AMCA 210-16. Secondly the use of hot-wire anemometry to measure the airflow through the test chamber. Methods of measuring static pressure behind the test fan with high accuracy and stable readings have also been studied. Different high-resolution loads have been studied to ensure high repeatability and reliability. During the development phase, prototypes of the different components were created to allow for testing and evaluation before a final design was chosen. After the designs for each component was decided, the final design was modelled in CAD before being fabricated and constructed. The construction mostly utilises styrene-acrylonitrile (SAN) but with certain components made from polylactic acid (PLA) and aluminium. Pressure readings are taken behind the fan being tested using static ports placed on the outside of a hollow diffuser, mounted on the inlet of the test chamber. The hollow diffuser is filled with foam to stabilise the pressure readings. The chosen method of measuring airflow through the test chamber was hot-wire anemometry for its broad measurement range, high accuracy and simplicity in implementation. The design of the high-resolution load was chosen to be a rotating gate with two ports. As the gate rotates these ports openor close. The rotating gate is driven by a stepper-motor. This design allowed for very fine control at high loads and ensures reliable operation with a minimal amount of moving parts. Tests with the finished test chamber have shown that the test chamber is capable of measuring and creating high-resolution fan curves with high repeatability. However the test chamber cannot measure static pressure at zero flow as there are currently leaks within the test chamber that allows a small amount of flow through the chamber when the variable load is fully closed. This leads to a systematic error when creatingfan curves, mainly at lower flow rates and higher static pressures. Further work with this test chamber is needed to reduce leaks, which would improve measurement precision.
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Vávra, Petr. "Vzduchotěsnost obvodových konstrukcí a kritických detailů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227861.
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In thesis is dealt with problematic of how the value of air permeability may be affected by properties for water vapour diffusion with regard to OSB material There were chosen two main brands of OSB at Czech trade market Two specimens of OSB with different thickness were chosen for each brand. As a first the specimens were tested for air tightness to work out a value of air permeability for each specimen. Afterwords, the testing was conducted for gaining properties of water vapour diffusion on each specimen. As a final assessment was analysed the impact of properties of water vapour diffusion on the air tightness for each specimen. The general meaning of gaining higher air tightness with higher water vapour resistance was proved . It was shown that with raising thickness is usually gotten higher value of water vapour diffusion resistance. However it could not mean getting high air tightness. The crucial parameter is the quality of the material for gaining higher resistance against water vapour diffusion as well as for higher airtightness.
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Smělý, Jakub. "Automatizované pracoviště pro měření vzduchotechnických veličin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230521.
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This thesis describes the design work for the measurement of air values. The first part describes the airflow, pressure build-up in pipes and losses due to airflow losses. There is also a description of fans and explain their characteristics depending on the pressure generated by airflow. The next part describes the design of the measuring chamber, electronics and control for fully automatic measurement of air quantities.
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Hernandez, Lindsey Danielle. "Magma Plumbing Systems along the Juan de Fuca Ridge." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587630136962186.
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Soares, Leonardo Vieira. "Pós-tratamento de esgoto sanitário tratado em reator anaeróbio compartimentado utilizando biofiltro aerado submerso." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-17112016-114657/.
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Nesta pesquisa, estudou-se a aplicação do biofiltro aerado submerso (BF) para pós-tratamento de esgoto sanitário tratado em reator anaeróbio compartimentado (ABR), visando adequar o efluente aos padrões estabelecidos pela legislação ambiental. A pesquisa foi dividida em duas etapas experimentais diferenciadas, principalmente, pela escala do biofiltro. Na primeira etapa, foi utilizado um biofiltro aerado submerso (BF1), em escala de laboratório, com volume útil de 7,82 L, sendo operado com tempo de detenção hidráulica de 3 horas, durante 117 dias. Na segunda etapa, foi empregado um biofiltro aerado submerso (BF2), em escala piloto, com volume útil de 178 L, sendo operado com tempo de detenção hidráulica de 6 horas, durante 47 dias. Em ambas as etapas, foram utilizadas matrizes cúbicas de espumas de poliuretano como meio suporte para imobilização celular e câmara de saturação - semelhante às utilizadas em sistemas de flotação por ar dissolvido - como mecanismo de aeração. O biofiltro BF1 obteve eficiências médias de remoção de DQOB, DBO5 e SST de 78%, 81% e 84%, respectivamente. O efluente apresentou as seguintes características médias: 22 mg DBO5/L, 49 mg DQOB/L e concentrações de SST e SSV inferiores a 20 mg/L em 96% dos valores medidos. A ocorrência do processo de nitrificação foi considerada pequena, atingindo eficiência máxima de conversão igual a 49%. Com relação ao biofiltro BF2, o desempenho do mesmo foi prejudicado pelo arraste do lodo do inóculo durante a primeira retro-lavagem e pelas baixas cargas orgânicas volumétricas aplicadas que dificultaram o crescimento dos microrganismos, não sendo observado se o reator entrou em regime permanente. As eficiências médias de remoção de DQOB, DBO5 e SST foram de 49%, 64% e 51%, respectivamente. . O efluente do biofiltro BF2 apresentou as seguintes médias: 98 mg DQOB/L, 49 mg DBO5/L e 19 mg SST/L. Quanto à inativação de microrganismos patogênicos, os resultados obtidos indicaram a necessidade de uma unidade de desinfecção após o sistema de pós-tratamento. O efluente do biofiltro BF1 apresentou concentrações médias de coliformes totais e fecais de 7,1 x 104 e 1,1 x 105 NMP/100 mL, enquanto para o biofiltro BF2 as concentrações foram de 3 x 106 e 6,4 x 104 NMP/100mL. A espuma de poliuretano comportou-se de forma adequada para imobilização da biomassa aeróbia, bem como para remoção de sólidos suspensos, devida a sua porosidade (90%) e capacidade de absorção. A câmara de saturação mostrou-se eficiente quanto ao processo de saturação de oxigênio e, quando operada com tempos de detenção hidráulica significativos, contribuiu com o processo de tratamento do efluente anaeróbio.In this research, the application of the submerged aerated biofilter (BF) for post-treatment of domestic wastewater treated in anaerobic baffed reactor (ABR) was studied, seeking to adapt the effluent to established patterns by the environmental legislation. The research was divided in two differentiated experimental stages, mainly, for the scale of the biofilter. In the first stage, a submerged aerated biofilter (BF1), on laboratory scale, with useful volume of 7,82 L, being operated with hydraulic detention time of 3 hours was used for 117 days. In the second stage, a submerged aerated biofilter (BF2), on pilot scale, with useful volume of 178 L, being operated with hydraulic detention time of 6 hours was used for 47 days. In both stages, cubic matrices of polyurethane foam were used as a supports for cellular immobilization and pressure chamber, similar those used then in flotation system for dissolved air, as aeration mechanism. The biofilter BF1 obtained medium efficiencies of removal of BOD5, CODB and TSS 81%, 79% e 84%, respectively. The effluent presented the following medium characteristics: 22 mg BOD5/L, 49 mg CODB/L and concentrations of TSS and VSS lower than 20 mg/L in 96% of the measured values. The occurrence of the nitrification process was considered small, reaching maximum efficiency of conversion of 49%. About the biofilter BF2, its performance was harmed for the lost of sludgeseeding in effluent during the first backwash and for the low applied organic volumetric loads that hindered the growth of the microorganisms, not being observed if the reactor entered in permanent regime. The medium efficiencies of removal of BOD5, CODB and TSS were 64%, 49% and 51%, respectively. The effluent of the biofilter BF2 presented the following medium concentrations: 98 mg CODB/L, 49 mg BOD5/L and 19 mg TSS/L. As a pathogens inactivation, the obtained results indicated the need of a unit of disinfectiafter the post-treatment system. The effluent of the biofilter BF1 presented medium concentrations of total and fecal coliforms of 7,1 x 104 and 1,1 x 105 NMP/100 mL, while for the biofiltro BF2 the concentrations were 3 x 106 and 6,4 x 104 NMP/100mL, respectively. The polyurethane foam behaved in an appropriate way for immobilization of the aerobic biomass, as well as for removal of suspended solids, due its porosity (90%) and absorption capacity. The pressure chamber was shown efficient regarding the process of oxygen saturation, and, when operated with significant hydraulic detention times, it contributed with the process of treatment of the anaerobic effluent.
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Souza, Edson Victor de. "Uma contribuição para o pre-dimensionamento de reservatorios hidropneumaticos para atenuaçao de transitorios hidraulicos." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258748.
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Orientador: Paulo VatavukDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: O estudo do transitório hidráulico em condutos forçados tem grande relevância em projetos de sistemas de tubulações. A quantificação das pressões máximas e mínimas é de fundamental interesse para o projetista, a fim de que este possa dimensionar a tubulação e/ou prever dispositivos de proteção, cuja finalidade é amortecer as variações de carga, prejudiciais à vida útil da instalação. Neste trabalho optou-se pelo estudo de um destes dispositivos, o reservatório hidropneumático, que protege as instalações contra sobrepressões e subpressões, impedindo assim a descontinuidade do escoamento quando o sistema de bombeamento é desligado ou quando ocorre um fechamento rápido de válvula de bloqueio. O objetivo principal da presente pesquisa é o de formular tabelas e gráficos de aplicação para o pré-dimensionamento de reservatórios hidropneumáticos para a atenuação de transitórios hidráulicos em sistemas de condutos forçados, facilitando, desta maneira, o trabalho dos projetistas na escolha deste tipo de dispositivo de proteção de sistemas hidráulicos
Abstract: The evaluation of hydraulic transients is very important in the design of pipe networks. The determination of the maximum and minimum pressures is of great interest to the designer, so that he can size the pipes and/or design protection devices, with the objective of decrease head variations, that can decrease the instalation life. In this work, one of those devices was chosen for study, the air vessel, that protects the instalation against overpressures and underpressures, avoiding the interruption of the flow when the pumping system is turned off or when a valve closes too fast. The present work has the main objective of making charts and graphs of application for pre-sizing of air vessels to the mitigation of Waterhammer in pressure pipes by facilitating, in this way, the work of designers in choosing this type of protection of hydraulic systems
Mestrado
Recursos Hidricos
Mestre em Engenharia Civil
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Sava, Barišić. "Uticaj operacije katarakte na vrednost intraokularnog pritiska." Phd thesis, Univerzitet u Novom Sadu, Medicinski fakultet u Novom Sadu, 2016. https://www.cris.uns.ac.rs/record.jsf?recordId=101425&source=NDLTD&language=en.
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Katarakta i glaukom su po svom toku hronične i progresivne bolesti koji predstavljaju dva vodeća uzroka slepila u svetu. Obe bolesti su karakteristične za stariju životnu dob i često se sreću zajedno kod iste osobe. Katarakta podrazumeva hirurško lečenja, dok se lečenje glaukoma zasniva na snižavanju visine intraokularnog pritiska (IOP), medikamentoznim i hirurškim sredstvima. Cilj ovog istraživanja bio je da se utvrdi da li i u kojoj meri dolazi promene IOP-a i dubine prednje komore oka (ACD) nakon operacije katarakte, da li su preoperativne vrednosti IOP-a i ACD povezane sa postoperativnom visinom IOP-a i da li postoje razlike u ovim pojavama kod osoba operisanih od katarakte sa i bez prisutnog primarnog glaukoma otvorenog ugla (POAG). Rezultati ove studije pokazuju da postoji statistički značajno sniženje IOP-a 6 meseci nakon operacije katarakte. U poređenju sa preoperativnim vrednostima, ono iznosi prosečno 1,2 mmHg (7,5%) u grupi pacijenata bez POAG i 1,24 mmHg (6,49%) u grupi pacijenata sa POAG. Između dve grupe pacijenata nije postojala razlika u stepenu sniženja (p>0,05). Ustanovljen je statistički značajano veći (p<0,05) porast dubine ACD u grupi pacijenata sa POAG (1,03 mm; 34,8%) u odnosu pacijente bez glaukomske bolesti (0,92 mm; 30,37%). Rezultati korelacione analize, kao i regresionih univarijantih i multivarijantnih modela, pokazali su da statistički značajna povezanost postoji između preoperativne visine IOP-a i njegovog sniženja nakon operacije katarakte. Povezanost je bila pozitivnog smera i nije se uočena značajna razlika između obe grupe pacijenata. Ustanovljena je i pozitiva korelacija, bez statistički značajne razlike u obe grupe pacijenata, između PD indeksa (odnos preoperativnog IOP-a i ACD) i promene IOP-a nakon operacije katarakte. Preoperativna dubina prednje komore oka nije ispoljila povezanost sa postoperativnom promenom IOP-a. Naša studija je pokazala statistički značajno postoperativno sniženje IOP-a i povećanje dubine ACD nakon operacije katarakte, koja se održava šest meseci nakon operacije katarakte. Nije ustanovljena razlika u redukciji IOP-a između pacijenata sa i bez POAG. Ustanovljena je pozitivna korelacija preoperativne visine IOP-a i PD indeksa sa postoperativnom promenom IOP-a, što može biti od koristi prilikom odluke o optimalnom lečenju katarakte kod pacijenata sa POAG.Cataract and glaucoma are chronic and progressive diseases and they are two of the leading causes of blindness wold wide. Both diseases are typical for an older age and often coincide within the same person. Treatment of cataract is surgical, while glaucoma treatment is based on lowering the level of intraocular pressure (IOP) with various medical and surgical options. The aims of this research were to determine whether there is a change in IOP and in the depth of anterior chamber of the eye (ACD) after cataract surgery, whether preoperative values of IOP and ACD are related to postoperative IOP values and to determine if there are differences in these events between people operated from cataract with or without primary open angle glaucoma (POAG). Results of this study show that there is a statistically significant decrease of IOP six months after cataract surgery. Comparing with preoperative values, it was found to be 1.2 mmHg (7.5%) in group of patients without POAG, and 1.24 mmHg (6.49%) in patients with POAG. There was no statistically significant difference found between two groups of patients (p<0.05). Group of patients with POAG had significantly higher (p<0.05) deepening of ACD (1.03 mm; 34.8%), in comparison with patients with no glaucoma (0.92 mm; 30.37%). Results of correlation analysis, as well as univariate and multivariate regression models, have shown significant correlation of preoperative IOP and its reduction after cataract surgery. Correlation was of positive direction with no statistically significant differences among two groups of patients. There was a positive correlation found, with no statistically significant differences in both groups of patients, between PD index (ratio of preoperative IOP and ACD) and IOP change after cataract surgery. Preoperative anterior chamber depth has shown no correlation with postoperativeIOP change. Our study showed statisticallysignificant postoperative reduction ofIOP and deepening of ACD, lasting for six months aftercataract surgery. No difference inpostoperativeIOP decrease has been detected betweenpatients with or without POAG. A positivecorrelation of preoperativeIOP height and PDindex with postoperativeIOP change has beenestablished, which mayprove usefulfordecision of optimal treatmentof cataract among POAG patients.
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Weiss, Almiro. "Projeto, Construção e Validação de um Sistema de Compressão Uniaxial para Estimativa da Compactação do Solo." Universidade Estadual do Oeste do Parana, 2005. http://tede.unioeste.br:8080/tede/handle/tede/354.
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Previous issue date: 2005-07-01The compaction of the agricultural soils has worldwide importance because of the increasing of the farm with machinery resulting in the increasing of heavy machines for cultivation system, mainly, in the developed countries. The term, soils compaction refers to the compression carried out on the non-saturated soil, during which an increase of bulk density exists, producing the reduction of its volume of pores like a consequence. The excessive compaction has damaging consequences for the agriculture and environmental. For this reason, the state of soils compacting has received enough attention from researchers and agricultural farmers. The uniaxial compression has been used for predicting the agricultural soils compaction with so much efficiency. In accordance to the previous exposure, in this paper aimed the to develop an apparatus of uniaxial compression of the soil for testing in laboratory and evaluating its performance. The apparatus is composed by a pneumatic press, where the sample of soil is packaged in a metallic volumetric ring (made in steel carbon - ABNT 1020), with thickness of wall of 0,2 cm, internal diameter of 7,0 cm and two options of height of 2,4 cm and 4,8 cm. Cyclical loads of compression were applied to the sample in order to verify the variation of the soil deformation. A lineal transducer detects the samples behavior during the compression and uncompression (relaxation) uniaxial indicating in the digital counter s display the variations of measure of the sample deformation. Successive loads of 150, 200, 300, 400, 500, 600, 700 and 800 kPa were applied in periods of 60 s for compression and 120 s for uncompression of the sample. The results allowed conclude that the system presents answers with good precision and greater versatility with the variation of de samples size for compression.
A compactação dos solos agrícolas tem importância mundial em função do crescimento das áreas mecanizadas, acarretando o aumento de máquinas pesadas nos sistemas de cultivo, principalmente, nos países desenvolvidos. O termo compactação do solo refere-se a sua compressão realizada no solo não saturado, durante a qual existe um aumento de densidade produzindo como conseqüência redução de seu volume de poros. A excessiva compactação tem conseqüências danosas para a agricultura e para o meio ambiente. Por essas razões, o estado de compactação do solo tem recebido bastante atenção de pesquisadores e produtores agrícolas. O ensaio de compressão uniaxial tem sido utilizado para determinar a compactação dos solos agrícolas com muita eficiência. Face ao exposto, este trabalho estabeleceu como objetivo desenvolver um aparelho de compressão uniaxial do solo para ensaio em laboratório e avaliar o seu desempenho. O aparelho é composto por uma prensa pneumática, em que a amostra de solo fica acondicionada em um anel volumétrico metálico (feito em aço carbono - ABNT 1020, cromado), com espessura de parede de 0,2 cm, com diâmetro interno de 7,0 cm e com duas opções de altura de 2,4 cm e 4,8 cm. Cargas cíclicas de compressão foram aplicadas na amostra para verificar a variação da deformação do solo. Um transdutor linear detecta o comportamento da amostra durante a compressão e descompressão (relaxamento) uniaxial indicando no display do contador digital as variações de medida da deformação da amostra. Cargas seqüenciais de 150, 200, 300, 400, 500, 600, 700 e 800 kPa foram aplicadas em intervalos de tempo de: 60 s para compressão e 120 s para descompressão da amostra. Os resultados permitiram concluir que o sistema apresenta respostas com boa precisão e maior versatilidade, com variação do tamanho das amostras para compressão.
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Hrabovský, Jozef. "Kvantifikace mechanismů hydraulického odstranění okují." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234002.
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The issue of descaling is an important part of the forging and heat treatment of steel and semi products of steel production. Rising of new information and study of this process can increase efficiency and improve the surface quality after descaling. This thesis is focused on the mechanisms of the high pressure hydraulic descaling qualification and study of the chemical compounds of which the scales grown. To achieve all goals of this work and to get a comprehensive view of descaling process, few experimental measurements and numerical analyses were performed. All experimental measurements were focused on obtaining data about fundamental parameters and effects of the hydraulic descaling. The data obtained from measurements were applied to numerical analyses, which aimed to discover a deeper relation and to confirm the experimental results. This thesis can be divided into two main parts. The first part is devoted to parameters of the water jet study. The main studied characteristics of the high pressure hydraulic water jet were heat transfer coefficient and impact pressure at different modes such as standard or pulsating water jet. Experimentally measured data of these parameters were applied in numerical analyses. The numerical analyses were focused on studying the impact of the water jet parameters on the stresses in the oxide scale layers. A further water jet analysis was focused on the influence of the individual parts of the hydraulic system (such as water chamber or stabilizer) on its characteristics. In this part different types of the water chambers in combination with different types of stabilizers on the impact pressure values were investigated. These measurements were supported by fluid flow analysis through the hydraulic system. The second part of this work was focused on getting mechanical properties of the oxide scales from specimens prepared from standard structural steel and specimens from silicon steel. In this thesis, the influence of various parameters and characteristics was studied on these two types of steel. Mechanical properties of oxide scale structures were carried out by the Small Punch Test method. To obtain the fundamental mechanical properties such as Young´s modulus, yield strength and ultimate strength, material parameters based on the measured data were optimized. The whole work was carried out in order to get valuable and comprehensive results about high pressure hydraulic descaling process and influencing factors as well as about oxide scales themselves.
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Mu, Yang. "A distributed control system for low pressure plant growth chambers." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009183.
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Ďurdina, Lukáš. "Stanovení charakteristik spreje pomocí optických měřících metod." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230349.
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Diplomová práce se zabývá měřením charakteristik sprejů dvou tlakových vířivých trysek pro spalovací komoru malého turbínového motoru na zkušebním stavu za studena pomocí metod Particle Image Velocimetry (PIV) a fázové Dopplerovské anemometrie (PDA). Cílem měření bylo stanovit a porovnat charakteristiky sprejů obou trysek. Výsledky měření mají objasnit rozdílnost chování trysek za provozu a možný dopad na proces spalování. Úvodní teoretická část pojednává o základních fyzikálních principech atomizace kapalin, konstrukci a oblasti uplatnění tlakových vířivých trysek a o principech laserových diagnostických metod použitých při experimentálním měření. Nasledující část popisuje návrh a montáž zkušební trati a dalších zařízení navržených pro experimentální měření v této práci. Experimentální část se zabývá nastavením parametrů měřícího systému a zpracováním dat. Výsledky měření zahrnují vektorová rychlostní pole, axiální rychlostní profily a distribuce velikosti kapek pro různé provozní podmínky obou trysek.
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Horník, Jan. "Návrh komory výměníku tepla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241229.
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The master thesis is focused on the field of heat exchangers. Theoretical part makes the reader familiar with heat exchangers. Practical part is focused on design of chamber, which is part of heat exchanger. Practical part consists of strength calculation by standard ČSN EN 13445. Dimensions of tube sheet are gained in program Visual vessel design. Those parameters are used for creating of 3D model with accurate dimensions which is analyzed in ANSYS Workbench. Output of this analysis is evaluation by stress classification. Practical part is supplemented by drawing of heat exchanger.
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Weber, Fabian. "Optical Analysis of the Hydrogen Cooling Film in High Pressure Combustion Chambers." Thesis, Luleå tekniska universitet, Rymdteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76872.
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For performance optimisation of modern liquid cryogenic bipropellant rocket combustion chambers, one component which plays an important role in reducing the wall side heat flux, is the behaviour of the cooling film. At the Institute of Space Propulsion of the German Aerospace Center (DLR) in Lampoldshausen, hot test runs have been performed using the experimental combustion chamber BKM, to investigate the wall side heat flux which is -- among other factors -- dependent on cooling film properties. To gain more insight into the film behaviour under real rocket-like conditions, optical diagnostics have been applied. The chosen methods were shadowgraphy and OH* imaging producing optical data sets which are analysed in this study. In this context, a description of the necessary background information is given, concerning rocket combustion chambers, film cooling and optical diagnostics of O2/H2 combustion. The applied methodology for optical analysis is described, followed by a presentation of the results. During the test campaign, it became clear that the optical setup was not optimised for creating meaningful shadowgraphy recordings which is why the shadowgraphy data has to be treated as flame emission imaging. The behaviour of the gas layer adjacent to the chamber wall could be characterised based on qualitative (luminosity, LOx shadow, reflection, recirculation zone and flame shape) and quantitative (layer thickness, layer length, pressure conditions) analysis. The thickness could be identified for each load step and an average length of the layer was found as well. OH* imaging has been used supplementary to support the observations from the flame emission images. An in depth frame by frame analysis was not possible due to time constraints. However, the time averaged images yielded results in accordance to the flame emission and could give a relative figure for the temperature distribution in the combustion volume. An artefact in the data was found, stemming presumably from the image intensifier. This artefact needs to be researched for a future error reduction in the data of this and other campaigns. Additionally, the thickness of the layer suggested a correlation to the models for film cooling efficiency. Such a correlation could not be established. Nevertheless, the film cooling models show the same behaviour as the data obtained from the flame emission imaging. Finally, suggestions are given how the data analysis and the optical setup could be improved for future, similar campaigns.
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Krčál, Petr. "Frézování vnitřních závitů na tělesech vstřikovacích jednotek Bosch." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229162.
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At the beginning of this diploma thesis I describe the production of different types of threads (with special emphasis on the production of internal threads), then I discuss different types of application of abrasion resistant coating by PVD and CVD, I describe their main advantages and disadvantages. Further, this diploma thesis explains particular mechanisms and forms of tool wear on tool with coating. In the second part of this diploma thesis the analysis of the current status of the production of internal threads in the Rail (high-pressure chamber) is made. In the last part I compare six different threads cutters by the use of a scanning electron microscope
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Zlámal, Josef. "Hluk rovinných desek." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-377486.
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The master thesis summaries the findings results of a study focused on the spread of noise vibrating flat plates. Part of this thesis is measurements of flat plate noise in the anechoic chamber and finally their processing and evaluation. The next part of the thesis is focused on FEM acoustic simulation and comparing results with measurements.
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Amin, Anam. "Ecohydrological Partitioning in the Critical Zone: Analysis of the Soil-Plant-Atmosphere Flows by Means of Stable Water Isotopes." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3423188.
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Tree and small catchment scale studies are important in getting a detailed understanding of ecohydrological processes and the interactions between plants and water fluxes with respect to specific geology, climate, physiographic and topographic settings. However, such studies cannot explain the processes ongoing at large spatial and temporal scales and/or across the globe. Recent global-scale analyses based on water stable isotopes (2H and 18O) quantified the contribution of different water sources to plant transpiration. However, no previous studies have estimated the depth distribution of soil water uptake by plants, and its relation to climate, and plant group at the global scale.
Recently, numerous ecohydrological studies explored the controls of climate and physiographic settings on isotopic composition of plant water. However, the assessment of the critical postulates (i.e., no isotopic fractionation in plant tissues) behind the use of stable water isotopes have not been widely tested. Furthermore, recent literature has raised a concern regarding the lack of standardized methodologies for plant and soil materials sampling and water extraction. The accuracy of different water extraction methodologies and the technical parameters (such as system setup, extraction time and temperature), which may affect the isotopic composition of the soil and plant extracted waters and thus, our interpretation of the results, still need to be thoroughly investigated.
To deal with these issues, this thesis presents an integrated outlook by exploring plant water-relations through use of stable water isotopes. This approach moved from a global scale assessment of the soil water source exploited by plants and the main drivers (i.e., climate and plant functional type) controlling the isotopic compositions of xylem water. This analysis revealed soil water as main water source for plants. A new graphical inference method has been developed for the quantification of soil water depths contribution. The results indicated the largest overlap (up to 100%) for shallow soil water and xylem water in cold zone, while the overlap between deep soil water and xylem water was largest for arid and tropical climate zones (i.e. >75%). This method has a great prospective to be tested and applied at other study sites around the globe.
Such global or catchment scale water source quantification by stable water isotopes is based on fundamental underlying postulation, henceforth, as a second objective in this thesis, it was attempted to test the isotopic fractionation of plant water along the pathway from roots to leaves under a greenhouse setup. Besides this, the measured isotopic compositions were also evaluated towards their sensitivity to the plant water extraction method via an interlaboratory comparison of commonly used cryogenic vacuum distillation system for plant materials. The resulting isotopic composition of different plant tissue water (i.e., stem and core) showed no fractionation with some exception to the root water and soil water samples at depths >15 cm, which were isotopically enriched as compared to the irrigation water. The samples extracted in two labs were comparable, nevertheless this controlled experiment further highlights the urgency of such comparisons to be performed for other existing plant water extraction methodologies and across other plant species.
Thereupon a subsequent comparison of different plant water extraction techniques (Scholander-type pressure chamber vs. cryogenic vacuum distillation) was performed. Results indicated a significant difference in the isotopic values obtained by the two extraction methods and this difference was smaller for beech samples compared to the chestnut samples. In addition, different results were observed for δ2H and δ18O, i.e. larger differences between the plant water extraction methods and the samples were found for δ2H compared to δ18O.
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Li, Qi. "Acoustic noise emitted from overhead line conductors." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/acoustic-noise-emitted-from-overhead-line-conductors(90a5c23c-a7fc-4230-bbab-16b8737b2af2).html.
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The developments of new types of conductors and increase of voltage level have driven the need to carry out research on evaluating overhead line acoustic noise. The surface potential gradient of a conductor is a critical design parameter for planning overhead lines, as it determines the level of corona loss (CL), radio interference (RI), and audible noise (AN). The majority of existing models for surface gradient calculation are based on analytical methods which restrict their application in simulating complex surface geometries. This thesis proposes a novel method which utilizes both analytical and numerical procedures to predict the surface gradient. Stranding shape, proximity of tower, protrusions and bundle arrangements are considered within this model. One of UK National Grid's transmission line configurations has been selected as an example to compare the results for different methods. The different stranding shapes are a key variable in determining dry surface fields. The dynamic behaviour of water droplets subject to AC electric fields is investigated by experiment and finite element modelling. The motion of a water droplet is considered on the surface of a metallic sphere. To understand the consequences of vibration, the FEA model is introduced to study the dynamics of a single droplet in terms of phase shift between vibration and exciting voltage. Moreover, the evolution of electric field within the whole cycle of vibration is investigated. The profile of the electric field and the characteristics of mechanical vibration are evaluated. Surprisingly the phase shift between these characteristics results in the maximum field occurring when the droplet is in a flattened profile rather than when it is ‘pointed’.Research work on audible noise emitted from overhead line conductors is reviewed, and a unique experimental set up employing a semi-anechoic chamber and corona cage is described. Acoustically, this facility isolates undesirable background noise and provides a free-field test space inside the anechoic chamber. Electrically, the corona cage simulates a 3 m section of 400 kV overhead line conductors by achieving the equivalent surface gradient. UV imaging, acoustic measurements and a partial discharge detection system are employed as instrumentation. The acoustic and electrical performance is demonstrated through a series of experiments. Results are discussed, and the mechanisms for acoustic noise are considered. A strategy for evaluating the noise emission level for overhead line conductors is developed. Comments are made on predicting acoustic noise from overhead lines. The technical achievements of this thesis are summarized in three aspects. First of all, an FEA model is developed to calculate the surface electric field for overhead line conductors and this has been demonstrated as an efficient tool for power utilities in computing surface electric field especially for dry condition. The second achievement is the droplet vibration study which describes the droplets' behaviour under rain conditions, such as the phase shift between the voltage and the vibration magnitude, the ejection phenomena and the electric field enhancement due to the shape change of droplets. The third contribution is the development of a standardized procedure in assessing noise emission level and the characteristics of noise emissions for various types of existing conductors in National Grid.
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Solomon, Brad K. "Methods for Identifying Acoustic Emissions From the Front Face of a Small Piezoelectric Blower." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3542.
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This thesis focuses on identifying acoustic noise generating components in piezoelectric blowers through transverse velocity measurements and the development of a numerical fluid model. Piezoelectric ceramics have proven useful for many industries and areas of research involving: high precision actuators, noise control, ultrasonic devices, and many other areas. As of late, a unique adaptation of piezoelectric ceramics is surfacing in the area of pumping and cooling. Air pumps that use these ceramics replace the traditional electric motor, resulting in lower power consumption, less moving parts, constant pressure gradients, lower overall weight, and a low profile. The current drawback of this application is the acoustic radiation produced by the blowers. Since these blowers are new to market, little research or development has been done to characterize the noise emissions. This thesis studies the acoustic emissions from the front face of a Murata piezoelectric blower. Jet noise and structural vibrations are two acoustic sources of interest that are studied in this research. A Direct Numerical Simulation (DNS) of the fluid flow through a Murata blower is developed to better identify noise generating mechanisms. The model solutions predict trends in sound pressure levels (SPL) of the jet noise and volumetric flow rates. Both the SPL and flow rate are shown to be functions of critical geometrical dimensions within the flow path of a Murata blower. Important dimensional components are identified as well as non-influential ones. Design guidelines are given to reduce noise emission from the front side of a blower and increase the volumetric flow rate. The results of this research have a direct impact on the piezoelectric blower industry and future blower designs.
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Zia, Azhar. "Solid-state dye-sensitized solar cells measurements at different pressures and temperatures in a controlled vacuum chamber." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-211099.
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Battistini, Lorenzo. "Impact of future EU7 regulations on high performance gasoline-ICEs and possible innovative technologies for extension of lambda 1 operating range." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25674/.
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The aim of pollutant emissions legislation is to bring environmental benefit by helping reduce, for what road transport is responsible, the concentration of pollutants where levels are too high and endanger human health.
Europe is considering several changes in “post Euro 6d” regulation from 2025. Several measures have been proposed for Euro 7, most of which introduce new challenges in the development of high-performance turbocharged gasoline engine such as the extension of lambda 1 in the whole engine map.
In this Master Thesis, possible technologies to expand the engine operating range with lambda 1 in the entire engine map, without widely reducing the engine performances are analyzed. In particular the focus is on the Pre-Chamber Spark Ignition (PCSI), the Exhaust Gas Recirculation (EGR), the Miller Cylce, the Water Injection and the Ultra High Pressure Injection.
Subsequently, the modeling and validation in Simulink/Matlab of thermal models to analyze and monitor the exhaust gas temperature in the entire exhaust system is presented and explained. The aim of the modeling is integrating the modules into the Model-in-the-Loop environment and co-simulating with GT-Power/Simulink for a virtual pre-calibration of exhaust gas temperature control.
Finally, homologation cycles are run to obtain a first analysis feedback regarding the pre-calibration and to understand which are the cycle zones where the fuel enrichement will be necessary to reach the desired temperature.