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Univerzitet u Beogradu

1. Živković, Zdravko R., 1951-. Filtri sa površinskim akustičkim talasom za hemijske gasne senzore.

Degree: Elektrotehnički fakultet, 2016, Univerzitet u Beogradu

Elektrotehnika i računarstvo - Elektronika / Electrical Engineering and Computing - Electronics

Ova disertacija razmatra važne probleme u analizi i modelovanju senzora na bazi elemenata sa površinskim akustičkim talasima (PAT) kao i projektovanje i realizaciju PAT filtara koji su osnova za izradu senzora. Kod ovih elemenata je zastupljena specifična vrsta procesiranja signala, procesiranje u realnom vremenu: konverzijom električnih signala visokih učestanosti u mehanički talas, njegovu modulaciju merenom neelektričnom veličinom i ponovnu konverziju u električni signal. Predloženi su nov model i metod analize transverzalnih PAT hemijskih senzora, zasnovan na metodi ekvivalentnih električnih kola, koji se može lako primeniti na bilo koju podlogu, polimer i gas. Prezentirana je takođe primena predloženog modela za određivanje brzine površinskih akustičkih talasa u višeslojnoj podlozi što je neophodno za određivanje koncentracije gasa kao i primena razvijenog metoda za analizu hemijskih PAT senzora na višeslojnim podlogama. Predložen je algoritam za projektovanje PAT filtara sa uniformnim pretvaračima sa konstantnim grupnim kašnjenjem i realizovan prototip filtra koji je baza za izradu hemijskog senzora. U prvom delu se izlažu osnovi teorije površinskih akustičkih talasa. Sažeto se predstavljaju svojstva površinskih akustičkih talasa i odgovarajuća analiza, odnosno fizički i matematički modeli. Objašnjava se funkcionisanje PAT elemenata utemeljeno na prostiranju elastičnih mehaničkih talasa visokih učestanosti duž površine monokristalne piezoelektrične podloge (supstrata). Zatim se izlaže princip rada elemenata sa površinskim akustičkim talasima, a potom načini analize i modelovanja interdigitalnih pretvarača kao i celog PAT elementa. Princip rada, modelovanje i implementacija transverzalnih senzora koji su zasnovani na elementima sa površinskim akustičkim talasom se prvo obrazlažu u drugom delu. Sažeto se prikazuje originalni metod u modelovanju PAT biosenzora koji omogućuje određivanje funkcije prenosa i ulazne admitanse PAT elementa sa uniformnim pretvaračima u konačnoj formi za opšti slučaj opterećenja. Upotrebom ovog metoda, gde se ceo filtar predstavlja kao četvoropol a IDP-i i bezelektrodni deo admitansnim matricama, moguće je vršiti analizu i predikciju u svakom pojedinačnom slučaju biosenzora kao i u slučaju PAT transpondera. U ovom delu je predložen nov model i metod analize transverzalnih hemijskih gasnih senzora sa površinskim akustičkim talasima. Problem određivanja promene izlaznog električnog signala u funkciji koncentracije hemijskog agensa je rešen korišćenjem elektromehaničkog ekvivalentnog modela. U predloženom modelu gasni senzor se predstavlja kao četvoropol, interdigitalni pretvarači se predstavljaju mrežom sa tri para krajeva, a linija za kašnjenje prekrivena osetljivim slojem mrežom sa dva para krajeva. Određuje se promena izlaznog signala (napona ili učestanosti) u funkciji koncentracije gasa. Analizira se i uticaj osobina realnog PAT senzora, kao što je slabljenje usled prostiranja, koje se…

Advisors/Committee Members: Tošić, Dejan, 1957-.

Subjects/Keywords: SAW device; Surface acoustic wave filter; Interdigital transducer; RF SAW filter; SAW sensor; Analysis and modelling of SAW chemical vapor sensors; Multilayer substrate; Wave velocity; Design and realization of transversal RF SAW filter; software IDPMPAT

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Živković, Zdravko R., 1. (2016). Filtri sa površinskim akustičkim talasom za hemijske gasne senzore. (Thesis). Univerzitet u Beogradu. Retrieved from https://fedorabg.bg.ac.rs/fedora/get/o:11617/bdef:Content/get

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Živković, Zdravko R., 1951-. “Filtri sa površinskim akustičkim talasom za hemijske gasne senzore.” 2016. Thesis, Univerzitet u Beogradu. Accessed January 20, 2020. https://fedorabg.bg.ac.rs/fedora/get/o:11617/bdef:Content/get.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Živković, Zdravko R., 1951-. “Filtri sa površinskim akustičkim talasom za hemijske gasne senzore.” 2016. Web. 20 Jan 2020.

Vancouver:

Živković, Zdravko R. 1. Filtri sa površinskim akustičkim talasom za hemijske gasne senzore. [Internet] [Thesis]. Univerzitet u Beogradu; 2016. [cited 2020 Jan 20]. Available from: https://fedorabg.bg.ac.rs/fedora/get/o:11617/bdef:Content/get.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Živković, Zdravko R. 1. Filtri sa površinskim akustičkim talasom za hemijske gasne senzore. [Thesis]. Univerzitet u Beogradu; 2016. Available from: https://fedorabg.bg.ac.rs/fedora/get/o:11617/bdef:Content/get

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Alberta

2. Lecoanet, Alexandre J L. Finite Element Model of the Thermal Profile During Submerged Arc Welding with One and Two Electrodes.

Degree: MS, Department of Chemical and Materials Engineering, 2016, University of Alberta

The submerged-arc welding (SAW) process is used extensively in the manufacturing of pipes. The heat flow introduced by the welding operation has a significant impact on the properties of both the weld metal and the heat affected zone (HAZ). The work presented in this thesis aims to develop a numerical heat flow model to predict the temperature profile in piece welded using SAW as a function of the welding parameters. Measurement were done using instrumented thermocouples during an operation of SAW with one electrode. The models were then compared to the measurements and a sensitivity analysis was carried out on the density, the specific heat, the parameter called “ff” in the double ellipsoid model, and the Neumann boundary condition. The three models used are a point source model giving results similar to Rosenthal’s results, a model using a double ellipsoid heat source with constant thermal properties, and a model using a double ellipsoid heat source with varying thermal properties. The presence of the thermocouples linked to the data acquisition system used in the experiment disturbed the weld but workable data were still extracted. Then the comparison between the measurement and the simulations showed that the most accurate model is the one using a double ellipsoid heat source with varying thermal properties. It predicts well the heating and the cooling phases of all the temperature profiles recorded but it predicts the peak well only for the thermocouples located around 12 mm from the center of the plate closer it overestimates the peak. The sensitivity analysis showed that the most sensitive parameters are the thermal properties. It also showed that the parameter called “ff” in Goldak’s approach is sensitive. The Neumann boundary condition is not a sensitive parameter. Also when measurements are done using thermocouples close to the knowing the exact location of the thermocouples is crucial.

Subjects/Keywords: Submerged arc welding; SAW; Modelling of submerged arc welding; Modelling of SAW; Modelling; Finite element method; FEM; Finite element method SAW; Thermal profile; Temperature profile; Modelling temperature profile; Instrumented thermocouples; Varying thermal properties; Simulation; Simulation of SAW; Simulation of welding; FEM modelling of SAW; Quasi-steady state; Heat transfer in welding; Point source; Double ellipsoid source; Two electrode welding; Welding with two electrodes; Instrumented welds; Sensitivity of the thermal properties; Welding of X70; Welding of pipelines; Statistical analysis; Bead shape parameters; Removing outliers; Simulation of welding with COMSOL; Mixed boundary condition; Simulation with two point sources; Infinite elements; Application of infinite elements to welding; Heat tranfer in moving coordinate system; Welding; Multiple electrode welding; Sensitivity analysis; Sensitivity analysis on submerged arc welding; Sensitivity analysis on SAW; Temperature measurement during a welding operation; Temperature measurement during submerged arc welding; Temperature measurement during SAW; Modelling temperature profile during welding; Modelling temperature profile during submerged arc welding; Modelling temperature profile during SAW

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Lecoanet, A. J. L. (2016). Finite Element Model of the Thermal Profile During Submerged Arc Welding with One and Two Electrodes. (Masters Thesis). University of Alberta. Retrieved from https://era.library.ualberta.ca/files/czk51vg98f

Chicago Manual of Style (16th Edition):

Lecoanet, Alexandre J L. “Finite Element Model of the Thermal Profile During Submerged Arc Welding with One and Two Electrodes.” 2016. Masters Thesis, University of Alberta. Accessed January 20, 2020. https://era.library.ualberta.ca/files/czk51vg98f.

MLA Handbook (7th Edition):

Lecoanet, Alexandre J L. “Finite Element Model of the Thermal Profile During Submerged Arc Welding with One and Two Electrodes.” 2016. Web. 20 Jan 2020.

Vancouver:

Lecoanet AJL. Finite Element Model of the Thermal Profile During Submerged Arc Welding with One and Two Electrodes. [Internet] [Masters thesis]. University of Alberta; 2016. [cited 2020 Jan 20]. Available from: https://era.library.ualberta.ca/files/czk51vg98f.

Council of Science Editors:

Lecoanet AJL. Finite Element Model of the Thermal Profile During Submerged Arc Welding with One and Two Electrodes. [Masters Thesis]. University of Alberta; 2016. Available from: https://era.library.ualberta.ca/files/czk51vg98f

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