In order to evaluate the productivity of methane hydrate (MH) by the depressurization method, Japan Oil, Gas and Metals National Corporation and Natural Resources Canada carried out a full scale production test in the Mallik field, Mackenzie Delta, Canada in April, 2007. An extensive wire-line logging program was conducted to evaluate reservoir properties, to determine production/water injection intervals, to evaluate cement bonding, and to interpret MH dissociation behavior throughout the production. New open hole wire-line logging tools such as MR Scanner, Rt Scanner and Sonic Scanner, and other advanced logging tools such as ECS (Elemental Capture Spectroscopy) were deployed to obtain precise data on the occurrence of MH, lithology, MH pore saturation, porosity and permeability. Perforation intervals of the production and water injection zones were selected using a multidisciplinary approach. Based on the results of geological interpretation and open hole logging analysis, we picked candidate test intervals considering lithology, MH pore saturation, initial effective permeability and absolute permeability. Reservoir layer models were constructed to allow for quick reservoir numerical simulations for several perforation scenarios. Using the results of well log analysis, reservoir numerical simulation, and consideration of operational constraints, a MH bearing formation from 1093 to 1105 mKB was selected for 2007 testing and three zones (1224-1230, 1238-1256, 1270-1274 mKB) were selected for injection of produced water. Three kinds of cased-hole logging, RST (Reservoir Saturation Tool), APS (Accelerator Porosity Sonde), and Sonic Scanner were carried out to evaluate physical property changes of MH bearing formation before/after the production test. Preliminary evaluation of RST-sigma suggested that MH bearing formation in the above perforation interval was almost selectively dissociated (sand produced) in lateral direction. Preliminary analysis using Sonic Scanner data, which has deeper depth of investigation than RST brought us additional information on MH dissociation front and dissociation behavior.

A key remaining challenge in the design of hypersonic vehicles is the incomplete understanding of the process of boundary-layer transition. Turbulent heating rates are substantially higher than those for a laminar boundary layer, and large uncertainties in transition prediction therefore demand conservative, inefficient designs for thermal protection systems. It is only through close collaboration between theory, experiment, and computation that the state of the art can be advanced, but experiments relevant to flight require ground-test facilities with very low disturbance levels. To enable this work, a unique Mach 6 low-disturbance wind tunnel, previously of NASA Langley Research Center, is established within a new pressure-vacuum blow-down infrastructure at Texas A&M. A 40-second run time at constant conditions enables detailed measurements for comparison with computation. The freestream environment is extensively characterized, with a large region of low-disturbance flow found to be reliably present for unit Reynolds numbers Re < 11×10^6 m-1. Experiments are performed on a 5º half-angle flared cone model at Re = 10×10^6 m-1 and zero angle of attack. For the study of the second-mode instability, well-resolved boundary-layer profiles of mean and fluctuating mass flux are acquired at several axial locations using hot-wire probes with a bandwidth of 330 kHz. The second mode instability is observed to undergo significant growth between 250 and 310 kHz. Mode shapes of the disturbance agree well with those predicted from linear parabolized stability equation (LPSE) computations. A 17% (40 kHz) disagreement is observed in the frequency for most-amplified growth between experiment and LPSE. Possible sources of the disagreement are discussed, and the effect of small misalignments of the model is quantified experimentally. A focused schlieren deflectometer with high bandwidth (1 MHz) and high signal-to-noise ratio is employed to complement the hot-wire work. The second-mode fundamental at 250 kHz is observed, as well as additional harmonic content not discernible in the hot-wire measurements at two and three times the fundamental. A bispectral analysis shows that after sufficient amplification of the second mode, several nonlinear mechanisms become significant, including ones involving the third harmonic, which have not hitherto been reported in the literature.

This work is concerned with the characterization of slowly moving fluids and was carried out on the flow of water through a narrow sedimentation tank. Dispersion in the type of flow structure involved is caused mainly by the presence of large eddies and, due to the fact that shear stresses are small, these eddies persist for a considerable period of time. Two flow models are presented : The first model assumes the X- Y- velocity component pair to form a discrete state Markov process in time and dispersion equations for the mean concentration at a point, the variance as well as concentration cross correlations are generated. In the second model the velocity fluctuation components are assumed to be independent, time-stationary Markov processes with normal probability density functions. The stochastic differential equation describing dispersion of tracer is formulated with and without the effect of molecular diffusion and solutions to both cases are presented. Comparison of the model with experimental data obtained from tracer and anemometer measurements show that the model is capable of describing mean dispersion in a relatively small region of the tank and that the tracer experiments were insensitive to molecular diffusion. / Thesis (Ph.D.)-University of Natal, Durban, 1970.

This research describes the process of manufacturing and machining of wire and arc additive manufactured (WAAM) thin wall structures on integrated and non¬integrated WAAM systems. The overall aim of this thesis is to obtain a better understanding of deposition and machining of WAAM wall parts through an integrated system. This research includes the study of the comparison of deposition of WAAM wall structures on different WAAM platforms, namely an Integrated SAM Edgetek grinding machine, an ABB robot and a Friction Stir Welding (FSW) machine. The result shows that WAAM is a robustly transferable technique that can be implemented across a variety of different platforms typically available in industry. For WAAM deposition, a rise in output repeatedly involves high welding travel speed that usually leads to an undesired humping effect. As part of the objectives of this thesis was to study the travel speed limit for humping. The findings from this research show that the travel speed limit falls within a certain region at which humping starts to occur. One of the objectives of this thesis was to study the effect of lubricants during sequential and non-sequential machining/deposition of the WAAM parts. Conventional fluid lubricants and solid lubricants were used. In addition, the effect of cleaning of deposited wall samples with acetone was also studied. A systematic study shows that a significant amount of solid lubricant contamination can be found in the deposited material. Furthermore, the results indicate that even cleaning of the wire and arc additive manufactured surfaces with acetone prior to the weld deposition can affect the microstructure of the deposited material.

An experimental investigation into fully developed high aspect ratio channels was undertaken. A review of the literature reveals that there is a need for accurate measurement of the inner peak value of streamwise turbulence intensity despite the large number of studies already completed. The scattered data on this subject could be attributed either to insufficient channel size (aspect ratio or length) or to hot-wire spatial filtering. A new, high quality, channel flow facility was designed and constructed, considering the most recent geometric limitation provided in the literature. To obtain accurate results, data were acquired using hot-wire probes with constant viscous-scale sensing length and were corrected using the most recent correction formula proposed by Smits et al. (2011). The results show dependence of inner peak value on Reynolds number in channels flow - its magnitude increasing with increasing Reynolds number.

Wire bonding is the process of creating interconnects between the circuitry on a microchip and PCB boards or substrates so that the microchip can interact with the outside world. The materials and techniques used in this bonding process can cause a wide variation in bond quality, so wire bond reliability testing is very important in determining the quality and longevity of wire bonds. Due to the fact that microchips are encased in protective resins after bonding and their substrates attached to the larger device as a whole, once any single wire bond fails then it could jeapordize the entire device as the wire bonds cannot be individually replaced or fixed. Current methods of reliability testing are lengthy and often destroy the entire sample in the process of evaluation, so the availability of novel non-destructive, real-time monitoring methods as well as accelerated aging could reduce costs and provide realistically timed tests of novel wire bond materials which do not form Intermetallic compounds (IMCs) as rapidly as Au wire on Al substrates. In this thesis, five new chip designs for use in wire bond reliability testing are reported, focusing on the first joint made in a wire bond, called the ball bond. These chips are scaled either to test up to 55 test bonds simultaneously or just one at a time, introducing different requirements for microchip infrastructure capabilities, such as on-chip sensing/data bus, multiplexer, and switches able to operate under High Temperature Storage (HTS) which ranges from temperatures of 150-220 ??C. There are different heating requirements for each of these microchips, needing to be heated externally or containing on-chip microheaters to heat only the ball bond under test, and not the rest of the microchip or surrounding I/O pads. Of the five chip designs, sample chips were produced by an external company. Experimental studies were then carried out with two of these chip designs. They were specifically made to test novel methods of determining ball bond reliability using in-situ, non-destructive sensing, in real-time, while the ball bond undergoes thermal aging. Pad resistance as an analysis tool for ball bond reliability is proposed in this thesis as a new way of evaluating ball bond quality and allows for the testing of electrical connection without the need for specialized measurement probes or difficult bonding processes that contact resistance measurements require. Results are reported for pad resistance measurements of a ball bond under very high temperature storage (VHTS) at 250 ??C, a temperature exceeding typical HTS ranges to accelerate aging. Pad resistance measurements are taken using the four-wire measurement method from each corner of the bond pad, while reversing current direction every measurement to remove thermo-electric effects, and then calculating the average square resistance of the pad from this value. The test ball bond is aged using a novel on-chip microheater which is a N+ doped Si resistive heater located directly underneath the bond pad, and can achieve temperatures up to 300 ??C while not aging any of the I/O pads surrounding it, which are located ~180 ??m away. A 50 ??? resistor is placed 60 ??m away from the heater to monitor the temperature. The use of a microheater allows the aging of novel wire types at temperatures much higher than those permitted for microchip operation while thermally isolating the test bond from the sensing and power bonds, which do not need to be aged. Higher temperatures allow the aging process to be sped up considerably. The microheater is programmatically cycled between 250 ??C (for 45 min) and 25 ??C (for 15 min) for up to 200 h or until the pad resistance measurements fail due breakdown of the bonding pad. Intermetallic compounds forming between the ball bond and the pad first become visible after a few hours, and then the pad becomes almost completely consumed after a day. The pad resistance is measured every few seconds while the sample is at room temperature, and the increase in pad resistance agrees with the fact that Au/Al IMC products are known to have much higher resistance than both pure Au or Al. Also discussed are some aging results of Au wires and Pd coated Cu (PCC) wires bonded to Al bonding pads and aged at a temperature of 200 ??C in an oven for 670 h. The oven aged Au ball bonds also saw IMC formation on the surface of the bonding pad, much like the microheater tests. The PCC ball bonds became heavily oxidized due to lack of Pd on the surface of the ball, the wire portions did not oxidize much. In conclusion, the new structures have been demonstrated to age ball bonds faster than with conventional methods while obtaining non-destructive data. Specifically, the new microheater ages a test bond at an accelerated rate without having an observable effect on the I/O connections used to monitor the test bond. Pad resistance measurements correlate to the aging of the test bond and ensure the electrical integrity of the joint is checked.

Gas lift is a means of enhancing oil recovery from hydrocarbon reservoirs. Gas injected at the production riser base reduces the gravity component of the pressure drop and thereby, increases the supply of oil from the reservoir. Also, gas injection at the base of a riser helps to mitigate slugging and thus, improving the performance of the topside facility. In order to improve the efficiency of the gas lifting technique, a good understanding of the characteristics of gas-liquid multiphase flow in vertical pipes is very important. In this study, experiments of gas/liquid (air/water) two-phase flows, liquid/liquid of oil/water two-phase flows and gas/liquid/liquid (air/oil/water) three-phase flows were conducted in a 10.5 m high 52 mm ID vertical riser. These experiments were performed at liquid and gas superficial velocities ranging from 0.25 to 2 m/s and ~0.1 to ~6.30 m/s, respectively. Dielectric oil and tap water were used as test fluids. Instruments such as Coriolis mass flow meter, single beam gamma densitometer and wire-mesh sensor (WMS) were employed for investigating the flow characteristics. For the experiments of gas/liquid (air/water) two-phase flow, flow patterns of Bubbly, slug, churn flow regimes and transition regions were identified under the experimental conditions. Also, for flow pattern identification and void fraction measurements, the capacitance WMS results are consistent with those obtained simultaneously by the gamma densitometer. Generally, the total pressure gradient along the vertical riser has shown a significant decrease as the injected gas superficial velocity increased. In addition, the rate of decrease in total pressure gradient at the lower injected gas superficial velocities was found to be higher than that for higher gas superficial velocities. The frictional pressure gradient was also found to increase as the injected gas superficial velocity increased. For oil-water experiments, mixture density and total pressure gradient across the riser were found to increase with increasing water cut (ranging between 0 - 100%) and/or mixture superficial velocity. Phase slip between the oil and water was calculated and found to be significant at lower throughputs of 0.25 and 0.5 m/s. The phase inversion point always takes place at a point of input water cut of 42% when the experiments started from pure oil to water, and at an input water cut of 45% when the experiment’s route started from water to pure oil. The phase inversion point was accompanied by a peak increase of pressure gradient, particularly at higher oil-water mixture superficial velocities of 1, 1.5 and 2 m/s. The effects of air injection rates on the fluid flow characteristics were studied by emphasizing the total pressure gradient behaviour and identifying the flow pattern by analysing the output signals from gamma and WMS in air/oil/water experiments. Generally, riser base gas injection does not affect the water cut at the phase inversion point. However, a slight shift forward for the identified phase inversion point was found at highest flow rates of injected gas where the flow patterns were indicated as churn to annular flow. In terms of pressure gradient, the gas lifting efficiency (lowering pressure gradient) shows greater improvement after the phase inversion point (higher water cuts) than before and also at the inversion point. Also, it was found that the measured mean void fraction reaches its lowest value at the phase inversion point. These void fraction results were found to be consistent with previously published results.

The rotating-disk boundary layer is not only a simpler model for the study of cross-flow instability than swept-wing boundary layers but also a useful simplification of many industrial-flow applications where rotating configurations are present. For the rotating disk, it has been suggested that a local absolute instability, leading to a global instability, is responsible for the small variation in the observed laminar-turbulent transition Reynolds number however the exact nature of the transition is still not fully understood. This thesis aims to clarify certain aspects of the transition process. Furthermore, the thesis considers the turbulent rotating-disk boundary layer, as an example of a class of three-dimensional turbulent boundary-layer flows. The rotating-disk boundary layer has been investigated in an experimental apparatus designed for low vibration levels and with a polished glass disk that gave a smooth surface. The apparatus provided a low-disturbance environment and velocity measurements of the azimuthal component were made with a single hot-wire probe. A new way to present data in the form of a probability density function (PDF) map of the azimuthal fluctuation velocity, which gives clear insights into the laminar-turbulent transition region, has been proposed. Measurements performed with various disk-edge conditions and edge Reynolds numbers showed that neither of these conditions a↵ect the transition process significantly, and the Reynolds number for the onset of transition was observed to be highly reproducible. Laminar-turbulent transition for a ‘clean’ disk was compared with that for a disk with roughness elements located upstream of the critical Reynolds number for absolute instability. This showed that, even with minute surface roughness elements, strong convectively unstable stationary disturbances were excited. In this case, breakdown of the flow occurred before reaching the absolutely unstable region, i.e. through a convectively unstable route. For the rough disk, the breakdown location was shown to depend on the amplitude of individual stationary vortices. In contrast, for the smooth (clean-disk) condition, the amplitude of the stationary vortices did not fix the breakdown location, which instead was fixed by a well-defined Reynolds number. Furthermore, for the clean-disk case, travelling disturbances have been observed at the onset of nonlinearity, and the associated disturbance profile is in good agreement with the eigenfunction of the critical absolute instability. Finally, the turbulent boundary layer on the rotating disk has been investigated. The azimuthal friction velocity was directly measured from the azimuthal velocity profile in the viscous sublayer and the velocity statistics, normalized by the inner scale, are presented. The characteristics of this three-dimensional turbulent boundary-layer flow have been compared with those for the two-dimensional flow over a flat plate and close to the wall they are found to be quite similar but with rather large differences in the outer region. / <p>QC 20150119</p>

Magnetic nanoscale devices have shown great promise in both research and industry. Magnetic nanostructures have potential for non-volatile data storage applications, reconfigurable logic devices, biomedical devices and many more. The S-state magnetic element is one of the promising structures for non-volatile data storage applications and reconfigurable logic devices. It is a single-layer logic element that can be integrated in magnetoresistive structures. We present a detailed micromagnetic analysis of the geometrical parameter space in which the logic operation is carried out. The influence of imperfections, such as sidewall roughness and roundness of the edge is investigated. Magnetic nanowires are highly attractive materials that has potential for applications in ultrahigh magnetic recording, logic operation devices, and micromagnetic and spintronic sensors. To utilize applications, manipulation and assembly of nanowires into ordered structures is needed. Magnetic self-alignment is a facile technique for assembling nanowires into hierarchical structures. In my thesis, I focus on synthesizing and assembling nickel nanowires. The magnetic behaviour of a single nickel nanowire with 200~nm diameter is investigated in micromagnetic simulations. Nickel nanowires with Au caps at the ends were synthesized by electrochemical deposition into nanopores in alumina templates. One-dimensional alignment, which forms chains and two-dimensional alignment, which forms T-junctions as well as cross-junctions are demonstrated. Attempts to achieve three-dimensional alignment were not successful yet. I will discuss strategies to improve the alignment process.

The dissertation investigates the diagnostics of wire rope by using forced characteristics. The main object of research is defects of prestressed ropes using a dynamic systems characteristic. The primary purpose of this dissertation is to research the characteristics of a prestressed rope with outside of broken wire and to create research methodology of broken wires and determine its location. The paper approaches a few major tasks such as by experiment detecting the dynamic characteristics of the wire rope and detection broken wire on the surface of the wire rope using dynamic characteristics. Task 1 is formulated as the literature review found that the wire rope defects detected by using of the dynamic characteristics received little attention. Task 2 relates to the first problem solution, as measured by vibrating amplitude of broken wire, it is important to assess the reliability of measuring instruments. The introduction reveals the investigated problem, importance of the thesis and the object of research and describes the purpose and tasks of the paper, research methodology, scientific novelty, the practical significance of results examined in the paper and defended statements. The introduction ends in presenting the author’s publications on the subject of the defended dissertation, offering the material of made presentations in conferences and defining the structure of the dissertation. Chapter 1 analysis used literature. It contains a wire rope defects and diagnostic... [to full text] / Disertacijoje nagrinėjama plieninių lynų defektų nustatymas taikant jėgines charakteristikas. Pagrindinis tyrimo objektas yra įtemptų plieninių lynų defektų nustatymas naudojant lyno, kaip dinaminės sistemos, savybes. Pagrindinis disertacijos tikslas – ištirti įtempto plieninio lyno su išoriniame sluoksnyje nutrūkusiomis vielomis savybes ir sukurti nutrūkusių vielų bei jų vietos nustatymo tyrimų metodiką. Darbe sprendžiami keli pagrindiniai uždaviniai: eksperimentiškai nustatytos plieninio lyno dinaminės charakteristikos ir naudojant jas aptinkamos įtempto plieninio lyno paviršiuje nutrūkusios vielos buvimo vieta. Pirmasis uždavinys suformuluotas, nes atlikus literatūros apžvalgą nustatyta, kad plieninių lynų defektams aptikti naudojant dinamines charakteristikas skirta mažai dėmesio. Antrasis siejasi su pirmojo uždavinio sprendimu, nes kai matuojamos virpančios nutrūkusios vielos amplitudės, labai svarbu įvertinti matavimo priemonių patikimumą. Disertaciją sudaro įvadas, trys skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra. Pirmasis skyrius... [toliau žr. visą tekstą]