Geomechanical Characterization of Marcellus Shale

Understanding the reservoir conditions and material properties that govern the geomechanical behavior of shale formations under in situ conditions is of vital importance for many geomechanical applications. The development of new numerical codes and advanced multi-physical (thermo-hydro-chemo-mechanical) constitutive models has led to an increasing demand for fundamental material property data. Previous studies have shown that deformational rock properties are not single-value, well-defined, linear parameters. This paper reports on an experimental program that explores geomechanical properties of Marcellus Shale through a series of isotropic compression (i.e. σ[subscript 1] = σ [subscript 2] = σ[subscript 3]) and triaxial (i.e. σ[subscript 1] > σ[subscript 2] = σ[subscript 3]) experiments. Deformational and failure response of these rocks, as well as anisotropy evolution, were studied under different stress and temperature conditions using single- and multi-stage triaxial tests. Laboratory results revealed significant nonlinear and pressure-dependent mechanical response as a consequence of the rock fabric and the occurrence of microcracks in these shales. Moreover, multi-stage triaxial tests proved to be useful tools for obtaining failure envelopes using a single specimen. Furthermore, the anisotropic nature of Marcellus Shale was successfully characterized using a three-parameter coupled model.National Science Foundation (U.S.) (Grant 1429252

Shock tunnel studies of scramjet phenomena, supplement 5

A series of reports are presented on SCRAMjet studies, shock tunnel studies, and expansion tube studies. The SCRAMjet studies include: (1) Investigation of a Supersonic Combustion Layer; (2) Wall Injected SCRAMjet Experiments; (3) Supersonic Combustion with Transvers, Circular, Wall Jets; (4) Dissociated Test Gas Effects on SCRAMjet Combustors; (5) Use of Silane as a Fuel Additive for Hypersonic Thrust Production, (6) Pressure-length Correlations in Supersonic Combustion; (7) Hot Hydrogen Injection Technique for Shock Tunnels; (8) Heat Release - Wave Interaction Phenomena in Hypersonic Flows; (9) A Study of the Wave Drag in Hypersonic SCRAMjets; (10) Parametric Study of Thrust Production in the Two Dimensional SCRAMjet; (11) The Design of a Mass Spectrometer for use in Hypersonic Impulse Facilities; and (12) Development of a Skin Friction Gauge for use in an Impulse Facility. The shock tunnel studies include: (1) Hypervelocity flow in Axisymmetric Nozzles; (2) Shock Tunnel Development; and (3) Real Gas Efects in Hypervelocity Flows over an Inclined Cone. The expansion tube studies include: (1) Investigation of Flow Characteristics in TQ Expansion Tube; and (2) Disturbances in the Driver Gas of a Shock Tube

Strategies for reducing hydrocarbon emissions in diesel low temperature combustion

Government legislation on particulate matter (PM) and oxides of nitrogen (NOX) emissions have become increasingly stringent over the past decades. Future projections have led to internal combustion (IC)engine developers exploring advanced combustion technologies which may replace or supplement current state of the art systems. Advanced combustion technologies such as Low Temperature Combustion (LTC) cover a broad series of mechanisms that seek to attain in-cylinder Equivalence ratio (f) - Temperature (T) combinations during combustion which lead to acceptable emissions of exhaust PM and NOX. These are generally achieved by a combination of EGR dilution and extended ignition delays for mixture preparation. Another common feature of LTC is the poor combustion efficiency due to severe requirements placed on mixture quality as lower temperatures and oxygen concentrations reduce local ignitability limits. Therefore, a significant amount of work on LTC is centred around understanding the spatial and temporal development of inadequately prepared mixtures during LTC. The investigations presented in this thesis are expected to contribute to this body of work as they are predicated on the hypothesis that current mixture preparation methods are insufficiently adapted to conditions present in LTC combustion modes. [Continues.

Gamut extension algorithm development and evaluation for the mapping of standard image content to wide-gamut displays

Wide-gamut display technology has provided an excellent opportunity to produce visually pleasing images, more so than in the past. However, through several studies, including Laird and Heynderick, 2008, it was shown that linearly mapping the standard sRGB content to the gamut boundary of a given wide-gamut display may not result in optimal results. Therefore, several algorithms were developed and evaluated for observer preference, including both linear and sigmoidal expansion algorithms, in an effort to define a single, versatile gamut expansion algorithm (GEA) that can be applied to current display technology and produce the most preferable images for observers. The outcome provided preference results from two displays, both of which resulted in large scene dependencies. However, the sigmoidal GEAs (SGEA) were competitive with the linear GEAs (LGEA), and in many cases, resulted in more pleasing reproductions. The SGEAs provide an excellent baseline, in which, with minor improvements, could be key to producing more impressive images on a wide-gamut display

A numerical investigation of 3D structural behaviour for steel-composite structures under various travelling fire scenarios

202309 bcvcVersion of RecordRGCPublishe

Advanced Diagnostics, Control and Testing of Diesel Low Temperature Combustion

The conventional high temperature diesel combustion is constrained by the classical NOx-soot trade-off, so that any technique to reduce one emission generally increases the other. The simultaneous low NOx and soot can be achieved by lowering the combustion temperature and by preparing a cylinder charge of high homogeneity. However, the lowered combustion temperature may significantly reduce the fuel efficiency of such combustion cycles. Therefore, the overall objective of this work was to conduct a detailed analysis of the diesel LTC cycles that result in simultaneous low NOx and low soot, and to improve the LTC performance through advanced diagnostics and combustion control strategies. The empirical and analytical analyses in this dissertation provide an in-depth understanding of diesel LTC and present an effective strategy for navigating the narrow LTC corridors. The in-cylinder gas sampling tests culminated with the identification of an LTC NOx mechanism whereby the NOx reduction in the presence of combustibles was quantified on a crank angle-resolved basis. The intake gas treatment through catalytic oxidation and fuel reforming of EGR stabilized the LTC cycles. Novel flow management strategies were applied to improve the thermal response and the energy efficiency of the reforming operation. Adaptive combustion control techniques were developed to improve the fuel efficiency of the LTC cycles and to enable navigation within the narrow LTC corridors. A computationally efficient `Pressure Departure Ratio\u27 algorithm for estimating the combustion phasing in real-time was proposed along with a methodology for engine load management within-the-same-cycle, and were shown to improve the LTC operational stability. The detailed EGR analysis helped to develop a systematic LTC control strategy by quantifying the effects of intake charge dilution and boost pressure on the LTC performance metrics. Based on the empirical and analytical analyses, the load management and efficiency improvements of the LTC cycles were demonstrated with three different fuelling strategies as follows: (1) Single-injection LTC with heavy EGR at low loads, (2) Multi-shot LTC (early HCCI) with moderate EGR for mid-load operation, and (3) Split burning LTC for higher engine loads with DPF-tolerant soot

Polymeric Foams

Postprint (published version

ASR expansion behavior in reinforced concrete : experimentation and numerical modeling for practical application

Most practicing structural engineers are not well-equipped with the knowledge or tools necessary to adequately address the problem of alkali-silica reaction (ASR). While the mechanisms and consequences of ASR in plain, unloaded concrete are fairly well-understood, such a statement cannot be made about ASR-affected reinforced concrete (RC). Central to the problem is that the expansion behavior of ASR-affected RC behavior as influenced by restraint in the form of embedded reinforcing bars and sustained applied loads is unclear. It is these ASR-induced expansions in concrete that lead to cracking, possible strength and stiffness degradation of the material, and the introduction of unanticipated material stresses that may impair the durability, serviceability, functionality, and integrity of affected structures. In an effort to transition from a materials science perspective on ASR toward a practical structural engineering approach for addressing ASR in RC, experimental and analytical research was conducted with the goals of: 1) generating more insight into the mechanism of ASR expansion in RC and better assessing how a variety of structural details influence expansion behavior, 2) enlarging the database of information on ASR expansion behavior in RC within the literature, and 3) developing a new tool that could be used to reliably estimate life-cycle expansions for subsequent use in quantifying current and future load-carrying response of existing ASR-affected structures. Expansion monitoring studies were carried out at the Ferguson Structural Engineering Laboratory on a large-scale, biaxially reinforced concrete beam and large-scale, multi-axially reinforced concrete cubes affected by ASR. The multi-directional expansion behaviors of these elements were measured over time and with volumetric expansion development to evaluate the influences of different reinforcing schemes (e.g., amounts, directions, and layouts of reinforcement) on overall behavior. Using principles of mechanics, a new ASR expansion model, the Distributed Volumetric Expansion Pressure (DVEP) model, was developed to estimate the multi-directional distribution of volumetric expansions developing in RC structures. The DVEP model was designed as a non-incremental analysis tool accounting for constitutive relationships and utilizing simple, structural detailing inputs (e.g., reinforcement ratios and material properties) for rapid and accurate assessment of global RC expansion behavior by hand or within the framework of finite element analysis programs employing secant stiffness solution algorithms. The modeling approach was extensively validated and shown to be robust and capable of being implemented with limited subjective application. The results obtained from the numerical modeling of expansion behavior were used to preliminarily examine the consequences of expansion on RC load-deformation behavior. Finally, several recommendations for future work were provided.Civil, Architectural, and Environmental Engineerin

Compressing Genome Resequencing Data

Recent improvements in high-throughput next generation sequencing (NGS) technologies have led to an exponential increase in the number, size and diversity of available complete genome sequences. This poses major problems in storage, transmission and analysis of such genomic sequence data. Thus, a substantial effort has been made to develop effective data compression techniques to reduce the storage requirements, improve the transmission speed, and analyze the compressed sequences for possible information about genomic structure or determine relationships between genomes from multiple organisms.;In this thesis, we study the problem of lossless compression of genome resequencing data using a reference-based approach. The thesis is divided in two major parts. In the first part, we perform a detailed empirical analysis of a recently proposed compression scheme called MLCX (Maximal Longest Common Substring/Subsequence). This led to a novel decomposition technique that resulted in an enhanced compression using MLCX. In the second part, we propose SMLCX, a new reference-based lossless compression scheme that builds on the MLCX. This scheme performs compression by encoding common substrings based on a sorted order, which significantly improved compression performance over the original MLCX method. Using SMLCX, we compressed the Homo sapiens genome with original size of 3,080,436,051 bytes to 6,332,488 bytes, for an overall compression ratio of 486. This can be compared to the performance of current state-of-the-art compression methods, with compression ratios of 157 (Wang et.al, Nucleic Acid Research, 2011), 171 (Pinho et.al, Nucleic Acid Research, 2011) and 360 (Beal et.al, BMC Genomics, 2016)