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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.
1

ON SCALING OF BRAKE TEST SAE J2522

McKavanagh, David Sean 01 May 2020 (has links)
Friction brakes represent the most important safety feature literally in all vehicles and their rigorous “friction testing” is usually performed on several platforms/scales and completed with field tests. Since friction and wear are system properties, it is not trivial to design “small scale” tests and to correlate data generated at different levels of testing complexity. Nevertheless, the economy of the brake materials development process could be improved, when interpretation of friction and wear test data is based on a deeper/proper understanding of physics and chemistry of ongoing friction phenomena. This contribution follows the two series previously presented at SAE Brake Colloquia and compares the data generated in the full-scale brake dynamometer SAE J 2522 performance test (Link Engineering 2800M dynamometer) with data generated in bench-top (small scale) friction tester (Bruker UMT) equipped with environmental chamber controlling temperature. Scaling laws of physics were adopted for design of the small-scale testing procedure, however, a different scaling philosophy as well as different friction materials were used when compared to the previously reported findings. Identical commercial OEM brake pad samples containing biodegradable environmentally friendly fibers and commercial OEM cast iron rotors were used in both dynamometer and scaled-down bench-top friction tests. Friction and wear surfaces/mechanisms were studied by using scanning electron microscopy (Quanta FEG 450 by FEI) equipped with the energy dispersive X-ray microanalysis (Inca System), and 3D optical microscope (NPFLEX by Bruker). Major conclusions proposed for this study can be summarized as follows: 1) Proper scaling by using physics principles allows for reasonable correlation of dynamometer and bench-top test data, although the results differentiate, particularly during fade and high temperature tests. These findings further support the previously published data and indicate that differences in scaling philosophy neither the types of tested materials have considerable impact on the generated data. 2) It is very important to properly select representative pad samples, as their size is considerably smaller compared to full pads. When the identical rotor materials are used, the repeatability of data is excellent and the sensitivity to typical differences of the bulk microstructure of cast iron is minimal. 3) When the testing results generated on dynamometer and bench tester matched well. the friction surfaces of full pads tested in dynamometer and the friction surfaces of small pad samples exhibited identical topography and chemistry.
2

Etablering av MALDI-TOF MS och webbaserad referensdatabas för identifiering av dermatofyter och mögelsvamp

Åkerman, Anna, Sayfawi, Refel January 2018 (has links)
Syftet med studien var att etablera Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry(MALDI-TOF MS) och onlinedatabasen Mass Spectrometry identification platform(MSI) som metod för identifiering av dermatofyter och mögelsvamp. Svamparna inkuberades 3 eller 6 dagar aerobt i 30°C på Sabouraud dextros agar. Två olika extraktionsmetoder användes innan analys med MALDI-TOF MS. Spektra analyserades med Flexcontrol version 3.4 och resulterade i scorevärde. De spektra som framkom skickades även till MSI för ytterligare analys där resultat erhölls som sannolikhet i procent. Av de ursprungliga 23 st prov identifierades totalt 22st(95,6%) efter 3 eller 6 dagars inkubation och med extraktionsmetod 1 eller 2. MSI databasen var mer omfattande än den interna databasen, men använde sig inte av de aktuella namnen. Behovet av artidentifiering kan ifrågasättas, då många dermatofyter och mögel inom samma släkte behandlas på samma sätt. Artbestämning för immunsupprimerade patienter kan däremot vara viktigt. Studien var lyckad och metoderna kommer tillämpas inom en snar framtid på Klinisk Mikrobiologi i Halmstad. / The purpose of this study was to establish Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry(MALDI-TOF MS) and the online database Mass Spectrometry identification platform(MSI) as a method for identification of dermatophytes and molds. The fungi were incubated 3 or 6 days aerobic in 30°C on Sabouraud dextrose agar. Two different extraction methods were used before analysis with MALDI-TOF MS. Spectra analyzed with Flexcontrol version 3.4 resulted in score values. The same spectra was later sent for analysis with MSI and the result obtained was seen as probability in percent. Of the original 23 samples a total of 22(95,6%) samples were identified after 3 or 6 days of incubation and by extraction method 1 or 2.  The MSI database was more comprehensive than the internal database, but did not use the current fungi names. The necessity of species identification can be questioned, since dermatophytes and molds within the same genera is treated the same way. Species identification for immunosuppressed patients could however be significant. The study was successful and the methods will be applied within a near future in the Clinical Microbiology laboratory in Halmstad.
3

Material identification using X-ray diffraction

Genetu Teggen, Linda January 2019 (has links)
This study reviews the theoretical and experimental aspects of the X-ray diffraction (XRD) technique and evaluates its use in identifying toxic elements or compounds in waste that has been incinerated. Many industries incinerate materials that contain large significant amounts of toxic elements, and these elements should be identified and re-moved to reduce environmental pollution. The aim of this project is to identify the elemental content of an incinerated ash sample, and to recommend a proper identification method when using XRD. Here, we test two ash samples (raw ash without any treatment and ash that has been stabilized by washing) using the software DIFFRAC.EVA that is integrated into Bruker’s diffractometer D2Phaser to match different diffraction patterns to identify the contents of the ash sample. Finally concluding the results XRF is more suitable than XRD for ash surveil-lance.
4

Lek brukeres informasjonsbehov i møte med systemer som brukerkunstig intelligens

Schramm, Helena January 2022 (has links)
As artificial intelligence becomes more widespread, the need forexplanations on how the technology actually works increases.Previous research in the area has mainly focused on studyingexplanations for technologists and domain experts. Moreover, theuser's need for information is rarely accounted for. The purpose ofthis study is to examine which information needs lay users have indealing with the systems that employ artificial intelligence thatsurround them in their daily lives. In order to achieve the purpose ofthe study, as well as building on results from previous research,Netflix was chosen as the object of study. A qualitative study usingsemi-structured interviews was conducted. The research materialwas later analyzed, using thematic analysis. The results show thatthe users’ mental model, and the lack of information from Netflix,affected the users’ information needs. All participants expressedthat the information provided by Netflix was insufficient and thatthey wanted more information. / I takt med at kunstig intelligens blir tatt i bruk av stadig fleresystemer, øker behovet for forklaringer om hvordan teknologienfungerer. Tidligere forskning innen området har hovedsakeligfokusert på å studere forklaringer for teknologer ogdomeneeksperter. Brukernes faktiske informasjonsbehov gjøressjelden rede for. Hensikten med denne studien er å undersøkeinformasjonsbehovet lekbrukere har i møte med de systemer somomgir dem i dagliglivet, som benytter seg av kunstig intelligens. Forå oppnå hensikten med studien, samt å ta hensyn til forslag fratidligere forskning, ble Netflix valgt som studieobjekt. Det blegjennomført en kvalitativ studie med semistrukturerte intervjuer.Materialet som ble samlet inn ble analysert ved hjelp av tematiskanalyse. Resultatet viser at brukerens mentale modell ogmanglende informasjon fra Netflix påvirket deresinformasjonsbehov. Alle deltakerne uttrykte at informasjonen fraNetflix var mangelfull, samt at de ønsket mer informasjon.

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