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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.
21

The Study of Electromagnetic Shielding for Multiwall Carbon Nanotube Composites

Chang, Chia-Ming 12 February 2008 (has links)
The shielding effectiveness (SE) of the novel multiwall carbon nanotube (MWCNT) plastic composites is studied for the purpose of the electromagnetic interference (EMI) protection and the electromagnetic susceptibility (EMS) improvement in the application of the optical transmitter and receiver modules. The experimental results showed that the liquid crystal polymer (LCP) based MWCNT composites can exhibit a high SE of 38 dB ~ 45 dB within the frequency range of 1 GHz ~ 3 GHz. The shielding capability was demonstrated by examining the electromagnetic susceptibility performance of the optical transmitter and receiver modules, which were packaged by the MWCNT-LCP composites. The EMS performance was evaluated by eye diagram and bit-error-rate test in a 2.5 Gbps lightwave transmission system. The results showed that the MWCNT-LCP composite packaged modules with more weight percentage of the MWCNTs can exhibit a higher SE, and hence showed effective EMS performance, a better mask margin, and a lower power penalty. A novel polyimide (PI) plastic consisting of finely ionic liquid (IL) dispersed MWCNTs was also demonstrated to have high SE under a lower MWCNT loading. The experimental results showed that the IL dispersed MWCNT-PI composite can exhibit a high SE of 40 dB ~ 46 dB within the frequency range of 1 GHz ~ 3 GHz. By comparison, the composite fabricated by non-dispersed process required a higher loading of MWCNTs than the dispersed one. To understand the detailed intermolecular forces among MWCNTs, the dispersion mechanism of the MWCNTs is studied qualitatively. The aggregation of MWCNTs is from van der Waals forces among MWCNTs, and it can be dispersed by using IL dispersant. This is due to the predominant cation-
22

Nonlinear thermal stress/fracture analysis of multilayer structures using enriched finite elements /

Yildirim, Bora, January 2000 (has links)
Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 202-206).
23

Monomer and polyimide production for radiation shielding purposes in manned space exploration /

Bate, Norah G. January 2009 (has links)
Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaf 36). Also available via the World Wide Web.
24

Analysis of shielding requirements for a 14 Mev neutron generator

Bunker, James Francis, 1938- January 1963 (has links)
No description available.
25

Investigation and development of structural composite materials for use as electromagnetic shielding agents in the current aerospace industry.

20 October 2010 (has links)
Due to the nature of today's competitive electronics market, the development of new electronic / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2007.
26

The use of model compounds in a theoretical study of carbohydrate C-13 chemical shift effects

Durran, David Michael January 1996 (has links)
No description available.
27

Determination of the linear attenuation coefficients and buildup factors of MCP-96 alloy for use in tissue compensation and radiation protection

Hopkins, Deidre N. 24 July 2010 (has links)
The linear attenuation coefficient and buildup factor are a few of the important characteristics that need to be studied and determined prior to using a material clinically in radiation treatment and protection. The linear attenuation coefficient and buildup factor, as well as several other properties, will be determined for MCP-96 alloy to assess its use in radiation therapy. A narrow collimated beam of γ-rays from sources with varying energies will pass through various thicknesses of MCP-96 alloy. The attenuation in the intensity of the beam will be determined for each varying thickness of the alloy. Plotting the thickness of the alloy versus the corresponding logarithmic intensity of the beam will allow calculation of the linear attenuation coefficient. The narrow beam geometry will then be replaced by the broad beam geometry to determine the buildup factor. Additional radiation is obtained through the broad beam geometry as a result of scattering and secondary radiation. Comparing the broad beam geometry to the narrow beam geometry allows determination of the buildup factor. Since the buildup factor depends upon the thickness of the MCP-96 attenuator, the energy of the beam, and the source-to-attenuator (STA) distance, it will be calculated using three parameters. It will be calculated as a function of thickness of MCP-96 alloy by using various thicknesses of the alloy; as a function of the energy of the incident radiation beam by using several sources with different beam energies; and finally, as a function of the source-to-attenuator distance by changing the position of the MCP-96 attenuators. / Department of Physics and Astronomy
28

Experimental investigation of plasma sail propulsion concepts using cascaded arcs and rotating magnetic field current drive /

Giersch, Louis Roy Miller. January 2005 (has links)
Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 111-113).
29

Buckling of graded coatings-A continuum model /

Chiu, Tz-Cheng, January 1999 (has links)
Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 154-162).
30

Análise da influência dos gases de proteção nas propriedades da solda a laser da liga Ti6Al4V / Analysis of gas shielding influence in the properties of Ti6Al4V laser welding

SILVA, DOUGLAS R. da 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:54:49Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:36Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP / FAPESP:06/52778-1

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