Test Slice Difference Technique for Low-Transition Test Data Compression

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REDUCING POWER DURING MANUFACTURING TEST USING DIFFERENT ARCHITECTURES

Power during manufacturing test can be several times higher than power consumption in functional mode. Excessive power during test can cause IR drop, over-heating, and early aging of the chips. In this dissertation, three different architectures have been introduced to reduce test power in general cases as well as in certain scenarios, including field test. In the first architecture, scan chains are divided into several segments. Every segment needs a control bit to enable capture in a segment when new faults are detectable on that segment for that pattern. Otherwise, the segment should be disabled to reduce capture power. We group the control bits together into one or more control chains. To address the extra pin(s) required to shift data into the control chain(s) and significant post processing in the first architecture, we explored a second architecture. The second architecture stitches the control bits into the chains they control as EECBs (embedded enable capture bits) in between the segments. This allows an ATPG software tool to automatically generate the appropriate EECB values for each pattern to maintain the fault coverage. This also works in the presence of an on-chip decompressor. The last architecture focuses primarily on the self-test of a device in a 3D stacked IC when an existing FPGA in the stack can be programmed as a tester. We show that the energy expended during test is significantly less than would be required using low power patterns fed by an on-chip decompressor for the same very short scan chains

Process simulation of wet compression moulding for continuous fibre-reinforced polymers

Interdisciplinary development approaches for system-efficient lightweight design unite a comprehensive understanding of materials, processes and methods. This applies particularly to continuous fibre-reinforced plastics (CoFRPs), which offer high weight-specific material properties and enable load path-optimised designs. This thesis is dedicated to understanding and modelling Wet Compression Moulding (WCM) to facilitate large-volume production of CoFRP structural components

An assessment of fluid flow and overpressure modelling m selected North Sea and Laramide basins

The occurrence of overpressure observed in petroleum bearing basins must be understood in terms of generation and distribution in order to build up a fluid flow history. Overpressure influences expulsion and migration of hydrocarbons from source rocks. This thesis details and interprets observations and results of a case study into aspects of overpressure distribution, fluid flow patterns, causative mechanisms, palaeo- pressure and subsequent pressure history, the surface expression of overpressure and the mechanical strength relationships of sealing rocks. One of the principle study areas was the Alwyn field in the Northern North Sea. The overpressure distribution over the field area was seen not to be uniform. Organic geochemical data indicated that the source of reservoired hydrocarbons and associated fluids was the Viking Graben depocentre. Fluid inclusion data recorded in specific diagenetic mineral phases interpreted fluid flow conditions of hydrocarbons into the reservoir under normal pressures but elevated temperatures. When combined with computer generated pressure models, these diagenetic events were exclusive of modelled overpressure periods. The greatest contribution of overpressure was modelled as being a result of compaction disequilibrium but withalikely contribution from the thermal cracking of oil to gas which would also account for the present day distribution of overpressure across the Alwyn field area. The Uinta Basin with its relatively simple burial and thermal history allowed the production of a model . : involving a temporal history of overpressure generation, fracture development, regional tectonism, hydrocarbon maturation and expulsion and the process of Gilsonite emplacement. It is inferred that initial hydraulically induced fracturing of the Green River and overlying formations was a result of combined overpressure due to disequilibrium and regional extension with a possible contribution from the maturation of the source rock. This study recognised that the hydrocarbon was emplaced under a high pressure regime with evidence provide. by the existence of forcibly injected hydrocarbon sills. Hydrocarbons fractionated in the pre-existing vertical fractures to leave residual highly viscous and immobile hydrocarbons in veins seen at the present day. The third major component of this study detailed results from an assessment of the mechanical capacity of sealing rocks with respect to specific composition and mineralogy. It was found that increasing organic carbon decreased the compressive strength of the tested shale specimens. This relationship was interpreted as a possible result of the interaction of alkaline fluids to produce a dispersant which acts to reduce the cohesion of the organic rich shale

Characterising, understanding and predicting the performance of structural power composites

Dramatic improvements in power generation, energy storage, system integration and light-weighting are needed to meet increasingly stringent carbon emissions targets for future aircraft and road vehicles. The electrification of transport could significantly reduce direct CO2 emissions; however, battery energy and power density limitations pose a major technological barrier. The introduction of multifunctional structural power composites (SPCs), which simultaneously provide mechanical load-bearing and electrochemical energy storage, offers new possibilities. By replacing conventional materials with SPCs, electrical performance requirements could be relaxed, and vehicle mass could be reduced; however, for SPCs to outperform monofunctional systems, significant performance and reliability improvements are still required. The use of computational models to support experimental efforts has so far been overlooked, despite wide recognition of the benefits of such a combined approach. The aim of this work was to develop predictive finite element models for structural supercapacitor composites (SSCs), and use them to investigate their mechanical, electrical, and electrochemical behaviour. A unit cell modelling technique was used to generate realistic mesoscale models of the complex microstructure of SSCs. The effects of composite manufacturing processes on the final performance of SSCs were investigated through characterisation and modelling of compaction and manufacturing defects. Numerical predictions of the elastic properties of SSCs were evaluated against data from the literature; and the presence of defects was shown to significantly degrade performance. Motivated by the large series resistance of SSCs, direct conduction models were developed to better understand electrical charge transport. Based on investigations of various current collector geometries, design strategies for the mitigation of resistive losses were proposed. To enable analysis of the combined mechanical-electrochemical behaviour of SSCs, an ion transport user element subroutine was developed but could not be validated. Overall, this work demonstrates that substantial improvements in the mechanical and electrical properties of SSCs are possible through control of the composite microstructure. The models developed in this work provide guidance for the optimisation of manufacturing processes and the design of new SSC architectures, and underpin the future certification and deployment of these emerging materials.Open Acces

Investigation of the microwave effect

Over the past decades, microwave sintering has been investigated, and the effects of microwave sintering have been demonstrated, however there is still uncertainty as to what is causing the enhancements known as the microwave effect . For a better understanding of the microwave effect , the effect of microwaves on the pore size distribution during densification has been investigated for submicron-sized zinc oxide (ZnO), which was sintered with conventional heating and varying amounts of microwave power but always maintaining exactly the same time-temperature profile. Initially, the density of the sintered samples was measured and compared; this proved that the densification of the hybrid sintered samples was increased and that the higher the level of microwaves used, the more it enhanced the densification. After this, the porosity was investigated through the use of nitrogen adsorption analysis, mercury porosimetry and Field Emission Gun Scanning Electron Microscopy (FEGSEM). Initially, it was found that sintering with microwaves reduces pores faster than for conventional sintering as expected. However, the experiments also revealed that the mechanisms of the reduction in the porosity were not different for microwave sintering compared to conventional sintering. When the porosity was compared at equivalent densities, it was observed that there was no significant difference, either in terms of the amount of porosity or the microstructure development. Since the structural development was the same for both conventional and hybrid sintering, it was concluded that the cause for the enhancement of the densification was enhanced diffusion caused by an additional driving force induced by the microwave field. The investigation of the solid-state reaction between zinc oxide and alumina was designed to investigate whether the diffusion associated with reactions was also enhanced by the use of microwaves. Therefore, zinc oxide and alumina samples were reacted as diffusion couples using conventional and hybrid heating, the latter with varying amounts of microwave power. The analyses of the reaction layer using FEGSEM showed an increase in the reaction product layer thickness when hybrid heating was used, with a higher level of microwaves yielding more growth. These results supported the view that the enhanced reaction rates were caused by enhanced diffusion, again caused by an additional driving force induced by the microwave field. For both the densification and reaction cases, the most likely additional driving force is considered to be the ponderomotive effect