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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

The synthesis and characterization of poly [oxy (2-acetyl-1, 4- phenylene) oxyterephthaloyl]

Onwunaka, Theophilus O. 01 July 1986 (has links)
This paper describes the synthesis and characterization of poly[ oxy(2-acetyl-1,4-phenyl ene) oxyterephthal oyl]. In our first attempt to synthesize the polymer, a high temperature polycondensation technique was used. This was done by polyesterification of 2-acetylhydroquinone and terephthaloyl chloride in o-dichlorobenzene. The first polymer was designated OBl-1. In our next attempt to make the polymer, OBl-2, we reacted the 2-acetyl hydroqui none with terephthal oyl chloride using a 50: 50 mixture of pyridine and chloroform as a sol vent. OBl-3 was synthesized using TCE (tetrachloroethane) as a solvent and a catalytic amount of pyridine in the reaction of the 2-acetylhydroquinone and terephthaloyl chloride. Our attempt to melt polymerize terephthalic acid. and 2-acetylhydroquinone di acetate was unsuccessful. These polymers were characterized by 13c NMR, lH NMR, FTIR (IR), polarizing optical microscopy, DSC, solubility, and solution viscometry.
2

Efficient Circuit Analysis under Multiple Input Switching (MIS)

January 2012 (has links)
abstract: Characterization of standard cells is one of the crucial steps in the IC design. Scaling of CMOS technology has lead to timing un-certainties such as that of cross coupling noise due to interconnect parasitic, skew variation due to voltage jitter and proximity effect of multiple inputs switching (MIS). Due to increased operating frequency and process variation, the probability of MIS occurrence and setup / hold failure within a clock cycle is high. The delay variation due to temporal proximity of MIS is significant for multiple input gates in the standard cell library. The shortest paths are affected by MIS due to the lack of averaging effect. Thus, sensitive designs such as that of SRAM row and column decoder circuits have high probability for MIS impact. The traditional static timing analysis (STA) assumes single input switching (SIS) scenario which is not adequate enough to capture gate delay accurately, as the delay variation due to temporal proximity of the MIS is ~15%-45%. Whereas, considering all possible scenarios of MIS for characterization is computationally intensive with huge data volume. Various modeling techniques are developed for the characterization of MIS effect. Some techniques require coefficient extraction through multiple spice simulation, and do not discuss speed up approach or apply models with complicated algorithms to account for MIS effect. The STA flow accounts for process variation through uncertainty parameter to improve product yield. Some of the MIS delay variability models account for MIS variation through table look up approach, resulting in huge data volume or do not consider propagation of RAT in the design flow. Thus, there is a need for a methodology to model MIS effect with less computational resource, and integration of such effect into design flow without trading off the accuracy. A finite-point based analytical model for MIS effect is proposed for multiple input logic gates and similar approach is extended for setup/hold characterization of sequential elements. Integration of MIS variation into design flow is explored. The proposed methodology is validated using benchmark circuits at 45nm technology node under process variation. Experimental results show significant reduction in runtime and data volume with ~10% error compared to that of SPICE simulation. / Dissertation/Thesis / Ph.D. Electrical Engineering 2012

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