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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.
61

Návrh specielního měřicího zařízení pro kontrolu sražení hran / The proposal of a special measuring device to check the chamfer

Novotný, Jan January 2014 (has links)
This diploma thesis consist of basic overview of contact and non-contact measuring methods used at present days across industrial Applications. On the base of given specification for designing of measuring station for measuring chamfer of rotary components The choice and evaluation of theoretical applicability for our application is performed. In the practical part of this diploma thesis The applicability is verified. Performance of these a few exemplary measuring shows possible way of design of constructional solution. All this in a close cooperation with company MESING.
62

Studies of atlas second level B-physics trigger

Li, Weidong January 2000 (has links)
No description available.
63

Charm hadron production in semileptonic b decays and the relative production fractions of weakly decaying b hadrons at the Z⁰ resonance

Evans, Martin David Treharne January 1998 (has links)
No description available.
64

Application of THz pulses in semiconductor relaxation and biomedical imaging studies

Bezant, Christopher David January 2000 (has links)
No description available.
65

Speciation of mercury by chromatography coupled with atomic spectrometry

Armstrong, Helen Elisabeth Louise January 2000 (has links)
A commercial GC-AFS instrument has been developed and optimised for the speciation of organomercury. This instrument couples a GC oven to a modified atomic fluorescence detector via a ceramic pyrolyser. Organomercury compounds in dichloromethane solvent were directly injected through a Programmable Temperature Vaporiser Injector onto a DBl Megabore column. Once separated, the compounds eluted from the column and were atomised in the pyrolyser then detected by AFS. The direct injection technique, ceramic pyrolysis design and argon purged detector have improved previous instrument designs by enhancing and maintaining sensitivity. The instrumental limit of detection was determined to be 0.25 pg Hg absolute. Methods were developed for the extraction of methylmercury from a variety of marine samples. The techniques were validated using mussel homogenate and dogfish liver (IAEA 142, SRM 8044 and DOLT-2) certified reference materials. An interlaboratory comparision exercise was participated in and a method was developed for the detemination of methylmercury in Fucus sea plant (IAEA 140). A concentration of 0.63 ± 0.006 ng g-1 was reported. The material is now certified at 0.626 +0.139 ng g-1. Of all the participating laboratories, this was the closest result to the certified value. The instrument and methods were also applied to soil and sediment samples. Once again validation was performed with a CRM sediment, IAEA 356. Although this material has been reported to give positive artifact formation when using a steam distillation sample preparation procedure, good agreement and no artifects were observed upon analysis. A further contaminated land, an uncontaminated soil and sediment sample were also studied. For all the samples studied by GC-AFS total mercury measurements were also made following an appropriate digestion procedure and CV-AFS. A gas chromatograph was also coupled with ICP-MS and HPLC was coupled to CV-AFS as comparative techniques. Both approaches were optimised and validated with CRM's. The GC-ICP-MS had the advantage of providing additional element information and confirmed the presence of methylmercury bromide in the final mussel homogenate extract. The HPLC approach found to be much less sensitive than the GC techniques and also suffered from vapour generation interferences. The PTV injector was considered for large volume injection and thermal desorption techniques. Injector breakdown problems were overcome by optimising the conditions and solid phase adsorbent for cold splitless injection. A recovery of 70% was achieved for a 50 ul large volume injection of methylmercury chloride in DCM. This technique indicated the possibility that LVI may in the future offer increased method sensitivity.
66

An experimental investigation of the lattice-magnetism interactions in rare earth and transition metal compounds

Taylor, Jonathan W. January 1999 (has links)
The interaction between magnetism and the nuclear lattice is investigated experimentally, using thermal expansion, magnetostriction, specific heat, magnetisation and neutron scattering measurements. Both localised moment systems, as represented by the rare earth compounds Tb2Agln, Pd2Gdln and Cu2Gdln, as well as transition metal compounds, Ni2MnGa and V20 3 have been characterised at low temperatures. Measurements of the lattice properties are important due to the intrinsic coupling of magnetic degrees of freedom to them. The response of the lattice to magnetic order, and also to applied magnetic fields have been probed by the use of the aforementioned techniques. Such techniques allow the direct determination of the coefficient of linear thermal expansion, over a wide temperature range and the forced magnetostriclion in applied fields of 0 to 7T. Indirect determination of the spontaneous magnetostriction and the total magnetic entropy contribution via measurements of isostructural compounds further enhance the range of experimental data available. The dynamic properties are characterised by spin polarised neutron scattering measurements. The experimental results are presented and discussed. Various methods of coupling lattice and electronic degrees of freedom have been investigated. It is argued that in order to fully understand and appreciate the low temperature properties of the materials investigated such a coupling must be taken into account.
67

Estudo comparativo de metodos de determinacao do tamanho de particula

PAPINI, CLAUDEMIR J. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:48:55Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:35Z (GMT). No. of bitstreams: 1 09604.pdf: 6894956 bytes, checksum: 537f0618ac453f105325642d96ab808b (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
68

Estudo sobre o gás ozônio formado no processo de irradiação industrial com cobalto-60 e seu impacto no meio ambiente / Study on ozone gas formed in the industrial radiation process with cobalt-60 and its impact on the environment

UZUELI, DANIEL H. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:42:10Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:57Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
69

Elaboração de indicadores de produção científica com base na análise cientométrica das dissertações e teses do IPEN / Construction of scientific production indicators based on scientometrics analysis of IPEN dissertations and theses

IGAMI, MERY P.Z. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:33:55Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:35Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
70

Materialcharakterisierung von Kunststoffen fürs Thermoformen unter Nutzung neuer Messtechnologien

Sanjon, Cedric, Kayatz, Fabian, Schult, Andre 29 May 2018 (has links) (PDF)
Für die Herstellung von Kunststoffformteilen, z.B. Verpackungen, Komponenten für Haushaltsgeräte, Automobil- oder Medizinbranche, werden aufgrund von Mikrostrukturen, neuen sowie hybriden Materialien und dem zunehmenden Kostendruck steigende Anforderungen an das Formteil, das Verfahren und den Prozess gestellt. Entsprechende Technologien zur Verbesserung des Umformprozesses stehen vor der Markteinführung oder werden derzeit entwickelt. Aufgrund des damit einhergehenden Anstiegs der Technologiekomplexität werden zunehmend Material- und Prozessmodelle eingesetzt. Die dienen der Technologieentwicklung, der Optimierung des Prozesses und bilden eine Hilfestellung bei der Inbetriebnahme. Ein Schwerpunkt und eine Herausforderung ist dabei die Materialmodellierung. Während des Umformens ins Werkzeug beim Thermoformen treten verschiedene Effekte auf: z. B. Dehnung und Verschiebung der Polymerketten, Bildung von amorphen und kristallinen Strukturen. Das sich daraus ergebende Verhalten ist durch geeignete Materialmodelle und deren Parametrisierung abzubilden. Ein gängiger Ansatz zur Bestimmung des Materialverhaltens und die damit verbundene Bestimmung der Materialparameter ist die Reverse-Engineering-Methode. Zu diesem Zweck stehen verschiedene Ersatzversuche zur Auswahl, z.B. Membrane-Inflation- Rheometer (MIR), Thermoformen-Material-Charakterisierung (TMC) und uniaxiale sowie biaxiale Zugversuche. Mit Hilfe geeigneter Modelle werden die Parameter entsprechend der experimentellen Daten gefittet. Für die Abbildung des Umformprozesses in einem numerischen Modell ist die Implementierung des Materialmodells in ein Prozessmodell notwendig. Um quantitative und qualitative Aussagen zur Übereinstimmung des numerischen Modells mit dem tatsächlichen Umformprozess zu erhalten, ist stets eine Validierung notwendig, indem experimentelle Simulationen durchgeführt und anhand ausgewählter Zielgrößen analysiert und den numerischen Ergebnissen gegenübergestellt werden. Zu diesem Zweck stehen verschiedene neue Messmethoden zur Verfügung, z.B. GEWAND, OCT, Hall-Effekt-Dickenmesser.

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