Hot mix asphalt (HMA) is a composite material that exhibits a nonlinear response that is dependent on temperature, type of loading and strain level. The properties of HMA are highly influenced by the type and amount of the constituents used and also depend on its internal structure. In such a material the variable effects of the compaction process assume a central importance in determining material performance. It is generally accepted that the theoretical knowledge about material behavior during compaction is limited and it is therefore hard to predict and manage (the effect of) a compaction process. This work makes an attempt to address such a specific need by developing a continuum model that can be adapted for simulating the compaction of hot mix asphalt (HMA) using the notion of multiple natural configurations. A thermodynamic framework is employed to study the non-linear dissipative response associated with HMA by specifying the forms for the stored energy and the rate of dissipation function for the material; a viscoelastic compressible fluid model is developed using this framework to model the compaction of hot mix asphalt. It is further anticipated that the present work will aid in the development of better constitutive models capable of capturing the mechanics of processes like compaction both in the laboratory and in the field. The continuum model developed was implemented in the finite element method, which was employed to setup a simulation environment for hot mix asphalt compaction. The finite element method was used for simulating compaction in the laboratory and in various field compaction projects.

Field compaction control is arguably the most common yet critical quality control procedure in geotechnical engineering. Since the early 1930s, the systematic process for performing quality control of compacted soils has often been performed by measuring the in-place dry unit weight (or density) and as-compacted soil moisture content after placement in a fill. However, the current practice overlooks several facts resulting from comparing soil prepared and compacted in the laboratory to soils placed and compacted in the field. These issues include comparing the compaction energy in the lab versus what is applied in the field, and the behavior of saturated soils in the laboratory to the performance of unsaturated soils in the field. To address some of these gaps, this study presents a new saturation-based framework for compaction quality control. The aim of this new framework is to reduce the uncertainties and assumptions of the compaction control process and provide practicing engineers with further insight into the key engineering attributes of compacted soils. The proposed saturation-based approach compares a degree of saturation difference to a normalized dry unit weight ratio, making saturation upon compaction the controlling diagnostic variable and the focus of the monitoring effort. In essence, the optimal compaction conditions will be referenced to a characteristic saturation state near 80%. Compared to the conventional quality control system for field compaction, the saturation-based approach is developed with the same field and reference data collected for most earth fill projects. The results of this approach enhance the engineering judgment required to match the laboratory reference values to the field conditions. For illustration purposes, the proposed saturation-based framework is applied to compaction control data of a large earth dam and compared against the conventional method side-by-side. The proposed framework builds on the unique physical features of the "family of curves" and expands the ability of the user to select the compaction criterion using that relationship to produce project design properties. Overall, the proposed approach enhances the knowledge of the physical behavior of compacted soils and provides a more comprehensive understanding of the long-term performance of compacted fills.

The proliferation of products from the consumer electronics industry (especially the communications market) has led to increasing consumer demand for cheaper, smaller form factor, efficient and low power consumption products with high computation power. This growing demand for cheaper and more efficient products has made it more desirable for Integrated Circuit (IC) manufacturers to integrate both analogue and digital circuits on the same silicon substrate in order to realise high performance mixed-signal IC's at cost effective prices. The concomitant technology advancements in the IC manufacturing process, especially in the Complementary Metal Oxide Semiconductor (CMOS) process and improvements made in the capabilities of Computer-Aided Design (CAD) tools is making greater system integration possible. However, one aspect of the process that is the bottleneck of yet further system integration and lower design lead time is test. While the digital sections of mixed-signal IC's are taking microseconds to test using well established digital structural test techniques which exploit efficient Design for Test (DFT) structures, the analogue sections are still being tested using functional test methods and consequently consume several seconds of expensive test time. The work presented in this thesis addresses the test problems associated with the analogue sections of mixed-signal IC's. Specifically, the work was aimed at developing an efficient and unified embedded mixed-signal test system capable of being adopted for both analogue circuit characterisation and production testing of mixed-signal IC's in order to reduce overall test time and cost. In this context, an Analogue Test Response Compaction Technique (ATRCT) has been developed using Delta-Sigma Modulation (AIM). This compaction technique produces a signature for an analogue macro under test, which relates to both the amplitude and frequency of the analogue output response. Fault simulation results relating to a two-stage CMOS operational amplifier and continuous-time state variable filter have shown that fault-coverage of greater than 80% is attainable when the ATRCT is employed in a production testing of linear analogue macros. Based on the ATRCT, a hardware efficient Analogue Built-In Selt-Test (ABIST) scheme is proposed. This work has also developed two characterisation techniques suitable for embedded linear analogue macros: 1) An alternative hardware efficient method of measuring the impulse response of linear analogue macros using AIM, which could be conveniently incorporated in an ABIST scheme. Simulation results of the AIM-based impulse response measurement system have shown that the accuracy of the technique is within ±0.5% of the expected impulse responses. 2) An analogue fault detection routine that uses AIM and correlation techniques to detect analogue amplitude and frequency faults within linear analogue macros. Combining the proposed AIM-based impulse response measurement technique with the proposed ABIST scheme or analogue fault detection routine will enable an efficient and unified embedded mixed-signal test system to be designed.

No description available.

Exposure of bare soil for long periods and onsite compaction create soil and water problems in asparagus production. This project aims to develop a cost effective and practical runoff and soil erosion management system. Two field trials (Phase 1 running from April - July 2012 and Phase 2 running from May - November 2013) tested different combinations of shallow soil disturbance (SSD) and mulch (straw and compost) application for soil erosion control. Cranfield University’s soil bin was used to test the effect of different tine configurations on soil disturbance. The results of this research corroborated observations that asparagus production can result in levels of unsustainable soil loss that will contribute to the degradation of the existing soil resource. The field trials demonstrated that a straw mulch applied at 6 t ha- 1 significantly improved key performance indicators (KPIs, i.e. runoff initiation, volume and rate; total soil loss; sediment concentration; total oxides of nitrogen; orthophosphate-P; and sediment-bound P) as compared with the Non-SSD Control. In general, SSD (irrespective of tine configuration) was ineffective at improving key performance indicators as compared with the Non-SSD Control. In the soil bin work, different tine configurations generated varying degrees and extent of SSD, with the modified para-plough giving the greatest soil disturbance for the least draught force. However, the differences in SSD observed in the soil bin had no effect on the KPI’s tested in the Phase 2 field trial. The effective treatments observed in the field trials only yielded cost savings to the farmer/grower when a high level of soil loss occurred. This research highlights the need to develop erosion control measures in asparagus fields, with wider implications to other row crops. However caution is needed, given the observed variation in effectiveness and reliability of in-field mitigation measures, especially during ‘extreme’ rainfall events.

[pt] A família de algoritmos BLAST é a mais utilizada pelos biólogos para a busca de similaridade entre biosseqüências, e por esta razão, melhoras nestes algoritmos, em suas estruturas de dados ou em seus métodos de acesso à memória secundária são muito importantes para o avanço das descobertas biológicas. Nesta dissertação, foi estudada detalhadamente uma versão do programa BLAST, analisando as suas estruturas de dados e os algoritmos que as manipulam. Além disso, foram realizadas medições de desempenho com o intuito de identificar os possíveis gargalos de processamento dentro das fases de execução do BLAST. A partir das informações obtidas, técnicas de compactação de dados foram utilizadas como uma estratégia para redução de acesso à memória secundária com o objetivo de melhorar o desempenho para a execução do BLAST. Finalmente, foi gerada uma versão modificada do BLAST no ambiente Windows, na qual foi alterado diretamente o código do programa. Os resultados obtidos foram comparados com os resultados obtidos na execução do algoritmo original. / [en] The BLAST is the sequence comparison strategy mostly used in computational biology. Therefore, research on data structures, secondary memory access methods and on the algorithm itself, could bring important optimizations and consequently contributions to the area. In this work, we study a NCBI BLAST version by analyzing its data structures and algorithms for data manipulating. In addition, we collect performance data for identifying processing bottleneck in all the BLAST execution phases. Based on this analysis, data compress techniques were applied as a strategy for reducing number of secondary memory access operations. Finally, a modified version of BLAST was implemented in the Microsoft Windows environment, where the program was directly altered. Finally, an analysis was made over using the results of execution of original BLAST against modified BLAST.

archives@tulane.edu / Over the past two centuries, coastal wetlands have become increasingly threatened by accelerated relative sea-level rise and anthropogenic modification. Engineered structures such as sea walls, levees, and drainage systems prevent natural processes of sediment distribution, reducing the resilience of coastal ecosystems. Land subsidence and shoreline erosion combine with global sea-level rise to make low-elevation coastal zones increasingly vulnerable to submergence. This dissertation examines processes of sediment accumulation, compaction, and relative sea-level rise in coastal wetlands and assesses strategies for restoration. I find that organic content strongly controls sediment compaction in wetland sediments. At least 80% of compaction happens quickly, largely within the first 100 years after deposition and in the top 1 m of the subsurface. This rapid shallow compaction is generally not recorded by traditional methods of measuring relative sea-level rise in low-elevation coastal zones (i.e., tide gauges and global navigation satellite systems). As a result, tide gauges generally underestimate rates of relative sea-level rise in low-elevation coastal zones and these areas may be at a greater risk of flooding than previously realized. However, despite accelerated rates of relative sea-level rise and rapid sediment compaction, coastal restoration efforts such as river diversions can be successful in building new land in some areas. I find that sediment deposition responds non-linearly to water discharge, reaching a maximum at moderate discharge. Wetlands are more likely to keep up with relative sea-level rise if hydrodynamic conditions are optimized to retain mineral sediment in targeted restoration areas. / 1 / Margaret Keogh

A thermodynamic framework was presented for the development of powderconstitutive models. The process of powder compaction through Equal ChannelAngular Extrusion (ECAE) at room temperature was modeled using the finiteelement analysis package ABAQUS. The simulation setup was used to conduct aparametric study involving varying the process parameters of ECAE, aimed ataiding the process design.Two powder compaction models, the Gurson model and the Duva and Crowmodel, were used to test their efficacy in modeling this process. Thethermodynamic framework was applied to derive the constitutive equations of theDuva and Crow model. Modeling parameters like friction coefficients, interactionconditions were determined by comparing the simulations for solid billet and anempty can with actual experimental runs for loads, shear angle and workpiece geometry. The simulations using the two powder constitutive models showed nosignificant difference in the stress in the powder during the extrusion.The results obtained from the 3-D simulations were also compared toexperiments conducted to compact copper powder with a size distribution of 10mto 45m. It was found through experiments that the powder does not fullyconsolidate near the outer corner of the workpiece after the first ECAE pass and theresults from the simulations were used to rationalize this phenomenon.Modifications made to the process by applying a back pressure during thesimulations resulted in a uniformly compacted powder region.Further, simulations were carried out by varying the process parameters likethe crosshead velocity, the friction coefficient between the walls of the die and thecan, can dimensions and material, shape of the can cross section etc and the effectof each of these parameters was quantified by doing a sensitivity analysis.

Predicting the performance of wells in compartmentalized reservoirs can be quite challenging to most conventional reservoir engineering tools. The purpose of this research is to develop a Compartmentalized Gas Depletion Model that applies not only to conventional consolidated reservoirs (with constant formation compressibility) but also to unconsolidated reservoirs (with variable formation compressibility) by including geomechanics, permeability deterioration and compartmentalization to estimate the OGIP and performance characteristics of each compartment in such reservoirs given production data. A geomechanics model was developed using available correlation in the industry to estimate variable pore volume compressibility, reservoir compaction and permeability reduction. The geomechanics calculations were combined with gas material balance equation and pseudo-steady state equation and the model was used to predict well performance. Simulated production data from a conventional gas Simulator was used for consolidated reservoir cases while synthetic data (generated by the model using known parameters) was used for unconsolidated reservoir cases. In both cases, the Compartmentalized Depletion Model was used to analyze data, and estimate the OGIP and Jg of each compartment in a compartmentalized gas reservoir and predict the subsequent reservoir performance. The analysis was done by history-matching gas rate with the model using an optimization technique. The model gave satisfactory results with both consolidated and unconsolidated reservoirs for single and multiple reservoir layers. It was demonstrated that for unconsolidated reservoirs, reduction in permeability and reservoir compaction could be very significant especially for unconsolidated gas reservoirs with large pay thickness and large depletion pressure.

This thesis studies the mechanics which can be associated with asphalt concrete compaction and develops continuum models in a general thermo-mechanical setting which can be used in future work to corroborate experimental compaction experiment results. Modeling asphalt concrete compaction, and also the ability to thereby predict response of mixes, is of great importance to the pavement industry. Asphalt concrete exhibits nonlinear response even at small strains and the response of asphalt concrete to different types of loading is quite different. The properties of asphalt concrete are highly influenced by the type and amount of the aggregates and the asphalt used. The internal structure of asphalt concrete continues to evolve during the loading process. This is due to the influence of different kinds of activities at the micro-structure level and to the interactions with the environment. The properties of asphalt concrete depend on its internal structure. Hence, we need to take into account the evolution of the internal structure in modeling the response of asphalt concrete. A theoretical model has been developed using the notion of multiple natural configurations to study a variety of non-linear dissipative responses of real materials. By specifying the forms for the stored energy and the rate of dissipation function of the material, a specific model was developed using this framework to model asphalt compaction. A compressible model is developed by choosing appropriate forms of stored energy and rate of dissipation function. Finally, a parametric study of the model is presented for a simple compression deformation. It is anticipated that the present work will aid in the development of better constitutive equations which in turn will accurately model asphalt compaction both in laboratory and in field. Distinct numerical approaches have been used to demonstrate the applicability of the theoretical framework to model material response of asphalt.