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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.
101

Transient Analysis on Structural Responses of Solder Joints under High-Speed Impact

Wang, Chang-chin 19 July 2007 (has links)
The purpose of thesis is to study the transient analysis of structural responses of solder joints under high-Speed impact. By using the experimental and simulation analysis. The experimental work can be divided into six parts, such as different impact speeds, different solder¡¦s components, different pad finishing, different UBM and Runner, and different thickness of PBO. From experiments, the variations of solder joint strength and mechanical properties were received and discussed and the failure mode. The empirical results show that maximum impact force on solder joints decreases as the impact speed increasing. The solder joint strength becomes stronger with the solder adopting elements of Ni and Co. The strength of solder ball was reduced significantly after a reflow. The intermetallic compound strength reduces with solder ball adopting high content of Ag. In impact test, the resistance of UBM of TiAl is better than that of TiAlTi. The runner adopted with the element Pd can improve the IMC reliablility to reduce Mode I failure. However, the PBO thickness has little influence on IMC strength. From the numerical results, in the consideration of strain rate on solder joint the mechanical properties of solder joint could be effectively investigated. According to the different IMC strength there will produce three failure modes of solder ball and the impact force becomes higher as the IMC strength setting higher. If the lower yield stress is considered in lower IMC strength, the impact force is not the highest of all, but the time duration is the highest of all.
102

Studies of the Reactions of EtMgOR (R= Et, Me)with Mg(CCR')2 (R'= tBu, SiMe3)

Lin, Chih-Chieh 25 July 2000 (has links)
The reactions of organomagnesium akoxides EtMgOR (R= Me, Et) with dialkynyl magnesium complexes Mg(CoCR¢F) (R¢F= tBu, SiMe3) give a series of the tetranuclear magnesium complexes [Mg4(OR)2Et2(CoCR¢F)4(THF)4] (R= Me, Et; R¢F= tBu, SiMe3). The reactions of diethyl magnesium complexes MgEt2 with alkynes HCoCR (R= tBu, SiMe3) give two different kinds magnesium complexes. One kind is [Mg4(OEt)2-Et2(CoCR)4(THF)4] (R= tBu, SiMe3); another kind is [Mg4O(CoCR)6(THF)4] (R= tBu, SiMe3). Besides, the reaction of diisopropylamide magnesium complex Mg(NiPr2)2 with alkyne HCoCtBu give first example including two different kind bridge ligands trinuclear magnesium complex Mg3(NiPr2)2(CoCtBu)4(THF)2.
103

Characterization of III-V Compound Semiconductor MOS Structures with Titanium Oxide as Gate Oxide

Yen, Chih-Feng 19 December 2007 (has links)
Due to the high electron mobility compared with Si, much attention has been focused on III-V compound semiconductors (gallium arsenide (GaAs) and indium phosphide (InP)) high-speed devices. The high-k material TiO2 not only has high dielectric constant (k = 35-100) but has well lattice match with GaAs and InP substrate. Therefore, titanium oxide (TiO2) was chosen to be the gate oxide in this study. The major problem of III-V compound semiconductors is known to have poor native oxide on it and leading to the Fermi level pinning at the interface of oxide and semiconductor. The C-V stretch-out phenomenon can be observed and the leakage current is high. The higher dielectric constant of poly-crystalline TiO2 film grown on GaAs can be obtained by metal organic chemical vapor deposition (MOCVD). But the high leakage current also occurred due to the grain boundary and defects in the poly-crystalline TiO2 film. The surface passivation of GaAs with (NH4)2Sx treatment (S-GaAs) could prevent it from oxidizing after cleaning and improve the interface properties of MOSFET. The fluorine from liquid phase deposited SiO2 solution can passivate the grain boundary of poly-crystalline MOCVD-TiO2 film and interface state. The high dielectric constant and low leakage current of fluorine passivated MOCVD-TiO2/S-GaAs can be obtained. The leakage current densities are 3.41 x 10-7 A/cm2 and 1.13 x 10-6A/cm2 at ¡Ó1.5 MV/cm, respectively. The Dit is 4.6 x 1011 cm-2eV-1 at the midgap. The dielectric constant can reach 71. In addition, the post-metallization annealing (PMA) is another efficiency way to improve the MOCVD-TiO2 quality. The mechanism of PMA process is from the reaction between the aluminum contact and hydroxyl groups existed on TiO2 film surface. Then the active hydrogen is produced to diffuse through the oxide and passivate the oxide traps. For PMA (350oC)-MOCVD-TiO2 on S-GaAs MOS structure, the leakage current densities can reach 2.5 x 10-7 and 5 x 10-7 A/cm2 at ¡Ó1.5 MV/cm, respectively. The dielectric constant and the Dit are 66 and 5.96 x 1011 cm-2eV-1, respectively. In order to avoid the leakage current from grain boundary of poly-crystalline TiO2, and liquid phase deposited TiO2 (LPD-TiO2) at low temperature can preserve the function of sulfur passivation. Therefore, the amorphous LPD-TiO2 was deposited on S-GaAs. The leakage current densities are 1.04 x 10-7 and 1.91 x 10-7 A/cm2 at ¡Ó0.5 MV/cm, respectively. The Dit is 3.2 x 1011 cm-2eV-1 and the dielectric constant is 48. The LPD-TiO2 film was deposited on (NH4)2Sx treated InP (S-InP), and the 4 x 100 £gm2 enhancement mode N channel InP MOSFET with LPD-TiO2 as gate oxide was fabricated, which showed the good characteristic. The normalized maximum gm is 43 mS/mm at VG = 1.3 V for VDS fixed at 1 V. The maximum calculated £gFE of 348 cm2/V¡Es at VDS = 1 V is obtained.
104

Synthesis of diazacrown ether and transition metal containing polymers by atom transfer radical polymerization and other methods /

Chan, Suk-hang. January 2002 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 219-222).
105

Structure/function analysis of the Drosophila fat facets deubiquitinating enzyme and analysis of the fat-dependent signaling pathway

Chen, Xin, 1975- 07 March 2011 (has links)
Not available / text
106

Mixed material integration for high speed applications

Krishnamurthy, Nicole Andrea 12 1900 (has links)
No description available.
107

Inventory models for all-or-nothing demand processes

Dominey, Matthew James Gray January 2001 (has links)
No description available.
108

The ecology of heteroblasty in Acacia

Forster, Michael Anthony, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW January 2009 (has links)
Heteroblasty defines a dramatic change in leaf form and function along a shoot and is a prominent feature of the genus Acacia (Mimosaceae). Function of different leaf types in Acacia (i.e. compound leaf versus phyllode) is well established yet it is unknown whether heteroblasty is a plastic trait. A fully factorial designed experiment established the light environment, and not nutrients or water, had a significant influence on heteroblastic development. Compound leaves, which have higher specific leaf area (SLA), are retained for longer under low irradiance and, specifically, under a low Red:Far Red light environment. Plants grown in high intraspecific density environments also retained compound leaves for longer. Blue light signals and greater ultraviolet radiation had no effect on heteroblastic development. Heteroblasty is thought to aid in seedling establishment however across all experiments there was no consistent evidence of improved plant performance. Rather, there was an optimal allocation of biomass to organs where resources were most limiting and this was more influential in assisting seedling establishment. Lastly, a meta-analysis of a global dataset of leaf traits found compound leaves to be similar to simple leaves but offset towards the cheap to construct with fast returns region of the leaf economics spectrum.
109

The ecology of heteroblasty in Acacia

Forster, Michael Anthony, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW January 2009 (has links)
Heteroblasty defines a dramatic change in leaf form and function along a shoot and is a prominent feature of the genus Acacia (Mimosaceae). Function of different leaf types in Acacia (i.e. compound leaf versus phyllode) is well established yet it is unknown whether heteroblasty is a plastic trait. A fully factorial designed experiment established the light environment, and not nutrients or water, had a significant influence on heteroblastic development. Compound leaves, which have higher specific leaf area (SLA), are retained for longer under low irradiance and, specifically, under a low Red:Far Red light environment. Plants grown in high intraspecific density environments also retained compound leaves for longer. Blue light signals and greater ultraviolet radiation had no effect on heteroblastic development. Heteroblasty is thought to aid in seedling establishment however across all experiments there was no consistent evidence of improved plant performance. Rather, there was an optimal allocation of biomass to organs where resources were most limiting and this was more influential in assisting seedling establishment. Lastly, a meta-analysis of a global dataset of leaf traits found compound leaves to be similar to simple leaves but offset towards the cheap to construct with fast returns region of the leaf economics spectrum.
110

Identifying the roles of dead ringer in the Drosophila eye /

Sibbons, Jane. January 2004 (has links) (PDF)
Thesis (Ph.D.)--University of Adelaide, School of Molecular and Biomedical Sciences, Discipline of Genetics, 2005? / "September, 2004" Bibliography: p. 119-136.

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