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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Green Room : A climate controlling grow-box for growing mushrooms and greens. / Green Room : En klimatkontrollerande tillväxtlåda för odling av svampar och växter.

Skullman, Bill, Herlin, Gabriella January 2023 (has links)
This report covers a project on a partially automated aeroponic and fungi growing system. The purpose is to evaluate if an enclosed space system can be automated to produce healthy crops of greens and fungi, and investigate how well the system can switch between these two growth modes. Factors that will be automated include regulation of temperature, humidity, air ventilation, and light exposure time. The research will be focused on Romaine lettuce and Golden Oyster mushroom. The methods used include research, hardware setup, software programming, chassis construction, and experiments. Relevant factors for the growing environment, such as lighting, temperature, and nutrient solutions were studied. The hardware components used in the project can shortly be described as follows. A real time clock ensure accurate timing for the microcontroller that regulates the indoor climate based on sensor readings. LEDs light up the chamber and a humidifier provide the roots access to a nutrient solution. A fan provides cooling, and filters block out unwanted microorganisms and fungi spores from the ventilation air. A display provides the user with relevant information. The system code written in C++ contain six main functions and two support functions. Depending on the growth mode, climate control functions are selected. The system has control variables allowing the administrator to set threshold levels for humidity and nutrient spray periods. The outer case of the chassis was made out of painted acrylic to block out light and retain moisture. The water-nutrient solution basin was designed to avoid leakage, net cups hold the plants in a raised bed, a base plate acts as flooring for the mushrooms, as well as a placement enforcer for the humidifier. An inner roof separates the moist growth chamber from the electronics compartment above. Two experiments were conducted in separate prototypes simultaneously for green sand mushrooms. For the mushroom experiment, a grow kit was installed after thorough cleaning. The fruiting process was monitored and photographed daily. Results showed successful mushroom growth and healthy fruiting bodies. For the greens experiment, a nutrient solution was mixed and lettuce seeds were placed in rock wool cylinders that were installed in net cups. Photographs were taken every three days to track the progress. The lettuce seeds germinated and started growing. Control variables were altered multiple times to maximize performance but optimal settings were not found. The plants died whilst unsupervised. The experiments were partially successful and demonstrated potential for growing both greens and mushrooms. The prototype was effective in maintaining set temperature and humidity levels. The parameters necessary for successful growth was effectively automated and the system has great potential for further improvements and automation. / Målet med projektet är att studera hur väl det går att odla både svamp och fotosyntetiserande växter i samma slutna, delvis automatiserande aeroponiskasystem. I projektet undersöks om det går att byta mellan de två odlingssätten och hur automatiserad processen kan vara. Produkten är tänkt att fylla utrymmet som hittats på marknaden för enkla odlingssystem hemma för i synnerhet svamp. Faktorer att ta hänsyn till är temperatur, luftfuktighet och ljusexponeringstid. Andra faktorer som pH värde eller byte av vattnet utesluts till följd av tid- och resursbegränsningar. Metoden är indelad i forskning, hårdvara, mjukvara, chassi och experiment. Forskningen täcker nödvändig information om faktorer relaterade till odling av både svamp och gröna växter i aeroponiska system. Exempelvis hur mycket ljus, vatten och näring som behövs. Kapitlet om hårdvara tar upp vilka komponenter som används och varför. I centrum är en microkontroller, en Arduino micro, som med hjälp av en realtidskolocka styr när belysningen ska lysa, när luftfuktaren ska vara på samt när fläktarna ska gå. En DHT11 sensor skickar information till Arduinon att agera utifrån. I mjukvara ingår hur koden är uppbyggd för att styra microkontrollern och hur användaren kan anpassa värden till sitt tycke. För att hjälpa användaren visas relevant data på en skärm. Produkten är uppbyggd med ett mörklagt och tätande skal av akrylplast. Vatten med eventuell näring för växtläget är samlat i en tät balja längst ner i lådan där luftfuktaren även är placerad. Över baljan vilar antingen ett svampodlingskit på en perforerad yta eller en hållare för odling av växter i nätkorgar med stenull. I taket är en 20W LED fäst på en kylfläns för kylning tillsamman med en närliggande fläkt. Allra högst upp är elektroniken, skyddad från fukten nere i lådan av ett lager akrylplast.Två experiment hölls parallellt med varandra i två likadana odlingskammare för att hinna utvärdera både svamp och fotosyntetiserande växter. Citronmussling valdes som svamp och Romansallad som växt. Experimenten dokumenterades regelbundet med fotografier och kommentarer om det som observerats. Experimenten var till stor del lyckade även om vissa parametrar behövde justeras under förloppet. Det aeroponiska systemet producerar svamp och växter av god kvalitet. Slutsatsen som kan dras är att det går att odla både svamp och växter i samma produkt. De parametrar som inkluderats inom projektets avgränsningar gick att automatisera. Det finns även goda möjligheter att förbättra automatiseringsnivån.
42

Early Stage Design of a Prefilmer at Siemens Energy : Numerical and Experimental Methodology

Hamzo, Jean-Pierre January 2023 (has links)
Design of atomizers for gas-turbine purposes are an important ordeal. The per-formance of the atomizer directly impacts the efficiency of the gas-turbine, andconsequently, the energy extracted from the turbine. Furthermore, the design ofthe atomizer can have an impact on reducing toxic emissions. On a global scale,gas-turbines can be considered crucial for the transition to renewable energy. Forengineers, designing of atomizers are however challenging. Turbulent flow, multi-phase interaction and chemical reactions are some of the complex physics involvedwhich has to be taken into consideration when designing the atomizer. Engineerstraditionally uses experimental testing for investigation of designs, and it is still verymuch a useful methodology. However, numerical simulations and CFD have recentlygained popularity due to being a more cost-effective methodology. In this work, theprocedure for designing a prefilm atomizer involving CFD (single phase model andmulti phase model) and experimental testing is documented. The details of the twonumerical models (a single phase model and a multi phase model) has been doc-umented as well as the experimental setup. The single phase model is used for aparametric study and experimental testing is used for evaluation of designs. Themulti phase model is aimed to replicate the experimental results. The validity ofthe numerical models and the experimental setup are discussed, and possible mod-ifications of the methodology for future studies are suggested. Finally, suggestionsfor how the prefilmer should be designed is suggested.
43

Atomization Characteristics of Camelina and Jatropha-Derived Drop-in Aviation Biofuels

Vankeswaram, Sai Krishna January 2015 (has links)
Biofuels in civil aviation is actively studied in recent years to identify potential alternative jet fuels to meet stringent environmental regulations imposed to tackle degraded air quality caused by fossil fuel combustion. In this context, the aviation industry prefers to develop ‘drop-in’ fuels which may not require substantial modifications in existing jet engine technologies. The thesis aims at evaluating the atomization characteristics of camelina- and jatropha-derived drop-in biofuels discharging from simplex swirl atomizer used in aircraft gas turbine engines. The test fuels are characterized in detail and all fuels meet current ASTM D7566 specifications. The experiments are conducted by discharging fuel spray into quiescent atmospheric air in a fuel spray booth to obtain spray characteristics such as fuel discharge behaviour, spray cone angle, breakup behaviour of swirling fuel sheet and spray drop size distribution. The characteristics of sheet breakup are deduced from the captured images of biofuel sprays and the measurements of spray droplet size distribution are obtained using Spraytec (laser-diffraction instrument). A systematic comparison is made between the biofuel sprays and the 100% Jet A-1 (conventional aviation kerosene) sprays to evaluate the drop-in feature of the biofuels. All the measured spray characteristics of the biofuel sprays follow the Jet A-1 both in qualitative and quantitative terms which ensure the drop-in nature of the tested biofuels. The minor differences observed in the comparison of the quantitative spray measurements are attributed to the variation in the fuel properties. This claim is supported using the predictions obtained from the liquid film breakup model and the empirical correlation reported in the literature for the determination of sheet breakup characteristics and mean drop size for sprays discharging from simplex swirl atomizers.
44

Stanovení charakteristik spreje pomocí optických měřících metod / Measurement of spray characteristics using optical measurement methods

Ďurdina, Lukáš January 2012 (has links)
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.
45

Mechanismus atomizace vybraných hydridotvorných prvků ve vyhřívaném křemenném atomizátoru a plazmovém atomizátoru s dielektrickou bariérou / Mechanism of atomization of selected hydride forming elements in an externally heated quartz tube atomizer and a dielectric barrier discharge atomizer

Juhászová, Lucie January 2019 (has links)
Atomization conditions for tin hydride in the planar dielectric barrier discharge (DBD) plasma atomizer were optimized with detection by atomic absorption spectrometry (AAS). The effects of apparatus arrangement such as the shape of a waveform function of the high voltage power supply source, DBD atomizer design as well as presence of a dryer tube filled with NaOH pellets to prevent residual aerosol and moisture transport into the DBD were investigated in detail. The optimal experimental setup consisted of a square wave high voltage power supply source coupled to a DBD with vapor-deposited electrodes in the presence of NaOH dryer upstream the DBD atomizer. Argon was found as the best discharge gas under a flow rate of 120 mL min-1 while the DBD optimum high voltage supply rate was 7 kV. A sensitivity of 0.05 s ng-1 Sn and a limit of detection of 1.1 ng mL-1 Sn were reached under optimized conditions. Optimization of the whole experimental setup resulted in 7-fold improvement of sensitivity compared to the original arrangement consisting of a sinusoidal source coupled to a DBD atomizer with glued electrodes in absence of the dryer. Keywords atomic absorption spectrometry, hydride generation, hydride atomization, quart tube atomizer, dielectric barrier discharge (DBD)
46

Generování hydridu bismutu pro atomovou absorpční a fluorescenční spektrometrii. / Hydride generation of bismuth for atomic absorption and fluorescence spectrometry.

Kolrosová, Marta January 2019 (has links)
This master's thesis deals with the optimization of conditions of chemical hydride generation (HG) of bismuth, its atomization and detection by atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS). Two types of atomizers were used for atomization of volatile species, a miniature diffusion flame for AAS as well as for AFS and a flame-in-gas-shield atomizer for AFS. At first, the parameters of HG in a flow injection mode were optimized - the concentration of hydrochloric acid, the concentration of sodium borohydride and the volume of the reaction coil. Subsequently, the atomization conditions were optimized using both atomizers. The parameters optimized were hydrogen fraction, total gas flow rate and observation height. Due to the more complicated construction of the FIGS atomizer, more parameters were studied, such as the oxygen flow rate through the capillary and the flow rate of shielding argon required for shielding the free atoms. A special part of the thesis dealt with the optimization of the optical path of the atomic fluorescence spectrometer, the selection of an interference filter and the optimization of a power supply of an electrodeless discharge lamp. It was found that under optimum conditions of generation, atomization and detection excellent detection limits...

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