Modern mines require systems that quickly deliver backfill to support the rock mass surrounding underground openings. Cemented Paste Backfill (CPB) is one such backfilling method, but concerns have been raised about CPB’s liquefaction susceptibility especially when the material has just been placed, and if it is exposed to earthquakes or large mining induced seismic events. Conventional geotechnical earthquake engineering for surface structures is now relatively advanced and well accepted, and so the objective of this thesis is to consider how that framework might be extended to assess the liquefaction potential of CPB. Seismic records were analyzed for earthquakes and for large mining induced events. Important seismological trends were consistent for rockbursts and earthquakes when the signals were recorded at distances as proximate as one kilometre, suggesting that the conventional earthquake engineering approach might plausibly be adapted for such design situations. For production blasts and for more proximate locations to rockbursts, much higher frequencies dominate and therefore new design methods may be required. Monotonic triaxial tests conducted on normally consolidated uncemented mine tailings demonstrated that the material is initially contractive up to a phase transition point, beyond which dilation occurs. Most importantly the material never exhibits unstable strain softening behaviour in compression, and only temporary or limited liquefaction in extension. The addition of 3% binder results in initial sample void ratios that are even higher than their uncemented counterparts, and yet the material friction is slightly enhanced when tested at 4 hours cure. These results suggest that the flow liquefaction phenomenon commonly associate with undrained loose sand fills will not occur with paste backfill. Cyclic triaxial test results analyzed in terms of number of cycles to failure for a given cyclic stress ratio exhibited a trend consistent with previous tests on similar materials. However, the addition of 3% binder and testing at 4 hours cure resulted in an order of magnitude larger number of cycles to failure – a surprising and dramatic increase, suggesting good resistance of the material to cyclic mobility. Future research is recommended to build on these results and develop more robust methods for liquefaction assessment of CPB.

As the world moves towards eliminating lead from consumer products, the microelectronics industry has put effort into developing lead-free solder paste. The major drawback of lead-free solder is the problems caused by its high reflow temperature. Variable frequency microwave (VFM) processing has been shown to allow some materials to be processed at lower temperatures. Issues addressed in this study include using VFM to reduce the solder reflow temperature, comparing the heating rate of different size solder particles, and comparing the reliability of VFM reflowed solder versus conventionally reflowed solder. Results comparing the effect of particle size on the heating rate of solder showed that the differences were negligible. This is due in part to the particle sizes overlapping. Many lead-free solder pastes reflow around 250℃. Results indicate that when using the VFM, lead-free solder paste will reflow at 220℃. The reliability of solder that was reflowed using the VFM at the reduced temperature was found to be comparable to solder reflowed in a conventional manner. Based on these findings, VFM processing can eliminate the major obstacles to making lead-free solder paste a more attractive option for use in the microelectronics industry.

The most prevalent method for the prevention of freeze-thaw and salt scaling damage in cement based materials is through the entrainment of air voids using air entraining chemical admixtures (AEA's). However, the common field methods for measuring air content in fresh concrete cannot distinguish between entrained and entrapped air voids, and the actual air content in the hardened concrete can vary from that determined by these tests due to a variety of factors such as workability, placing operations, consolidation efforts, and environmental conditions. Previous research has shown the ability of ultrasonic attenuation to distinguish between entrained and entrapped air voids in hardened cement paste, providing a foundation for an inversion procedure to calculate the size and volume content of the two scatterer sizes. While additional challenges are present with measurements in fresh paste, the use of an immersion setup can overcome the limitations of cement paste containment vessels and provide a means to measure air content from batching to placement. An immersion apparatus to monitor ultrasonic wave attributes including attenuation in fresh cement paste is designed and built. Results comparing air entrained and non-air entrained cement pastes are presented. Ultrasonic wave attributes are studied as a function of time and level of chemical air entrainer. Finally, recommendations are made to improve the accuracy of the immersion apparatus in order to develop an in situ, quality control procedure to quantify the air content of fresh cement paste from batching to placement.

The copy-and-paste paradigm is a fundamental operation in graphical user interfaces. However, existing copy-and-paste techniques have limitations, in particular in terms of efficiency and robustness against interruptions. This thesis is focusing on improving the user interface used to copy-and-paste objects across different contexts, such as a series folders. To improve this fundamental operation, a new copy-and-paste technique, called Bag-and-Dump, is proposed, implemented and evaluated. Bag-and-Dump aims to substantially reduce mouse movement by allowing the user to gather up (‘bag’) source data across different folders before ‘dumping’ the whole load at the destination. Additionally, Bag-and-Dump provides constant visual feedback in the form of a bag-like semantic cursor to increase robustness against interruptions. Bag-and-Dump was eval- uated against two standard copy-and-paste techniques (Keyboard Shortcuts and Drag-and-Drop) under a different number of contexts (folders) and with and without inter- ruptions. Results from the experiment not only showed that Bag-and-Dump indeed significantly reduces mouse movement, it also confirmed that Bag-and-Dump was 9% faster than Keyboard Shortcuts, one of the most popular copy-paste techniques among “expert users”.

Ag nanoparticle (NP) paste was fabricated and used to bond Cu wire to Cu foil at low temperatures down to 433 K. The relatively low bonding temperature promotes this method to be used in polymer-based flexible electronics, which cannot withstand high bonding temperatures due the possible melting of the polymer substrate. Unlike low-temperature soldering techniquies, bonds formed by this method was proved to withstand temperatures higher than the bonding temperature, which also promotes it to be used in electronics that operate at high temperatures. The Ag NP paste was developed by increasing the concentration of 50 nm Ag NP sol from 0.001 vol.% to 0.1 vol.% by centrifugation. The 0.001 vol.% Ag NP sol was fabricated in water by reducing silver nitrate (AgNO3) using sodium citrate dihydrate (Na3C6H5O7.2H2O). The bond was formed by solid state sintering among the individual Ag NPs and solid state bonding of these Ag NPs onto both Cu wire and foil. Metallurgical bonds between Ag NPs and Cu were confirmed by transmission electron microscopy (TEM). The Ag NPs were coated with an organic shell to prevent sintering at room temperature. It was found that the organic shell decomposed at 433 K, defining the lowest temperature at which a bond could be formed. Shear tests showed that the joint strength increased as the bonding temperature increased due to enhanced sintering of Ag NPs at higher temperatures. For better understanding of the melting and the sintering kinetics of Ag NPs, a molecular dynamics (MD) simulation based on the embedded atom method (EAM) was conducted to different sizes of Ag NPs with diameters between 4 nm and 20 nm. Programmed heating of an equal rate was applied to all sizes of NPs to find the complete melting and surface premelting points and sintering kinetics of the Ag NPs. The initial structural configuration of the Ag NPs was FCC truncated octahedral, which found to be stable for this size range of NPs. As a first step toward drawing a phase map of stable solid phases of Ag NPs at different temperatures and sizes of Ag NPs, the stability of the FCC truncated octahedral was studied for Ag NPs in size range of 1 nm to 4 nm. The smallest Ag NPs at which this configuration is stable was determined as 1.8 nm. Unlike the previous theoretical models, this MD model predicted both complete melting and surface premelting points for a wider size range of NPs. Melting kinetics showed three different trends that are, respectively, associated with NPs in the size ranges of 4 nm to 7 nm, 8 nm to 10 nm, and 12 nm to 20 nm. Ag NPs in the first range melted at a single temperature without passing through a surface premelting stage. Melting of the second range started by forming a quasi-liquid layer that expanded to the core, followed by the formation of a liquid layer of 1.8 nm thickness that also subsequently expanded to the core with increasing temperature, completing the melting process. For particles in the third range, the 1.8 nm liquid layer was formed once the thickness of the quasi-liquid layer reached 5 nm. The liquid layer expanded to the core and formed thicker stable liquid layers as the temperature increased toward the complete melting point. The ratio of the quasi-liquid layer thickness to the NP radius showed a linear relationship with temperature. Sintering kinetics of two Ag NPs in the size range of 4 nm to 20 nm, and sintering of three and four Ag NPs of 4 nm diameter was also studied by MD simulation. The sintering process passed through three main stages. The first was the neck formation followed by a rapid increase of the neck radius to particle radius ratio at 50 K for 20 nm particles and at 10 K for smaller NPs. The second was characterized by a gradual linear increase of the neck radius to particle radius ratio as the temperature of the sintered structure was increased to the surface premelting point. A twin boundary was formed during the second stage that relaxed the sintered structure and decreased the average potential energy (PE) of all atoms. The third stage of sintering was a rapid shrinkage during surface premelting of the sintered structure. Based on pore geometry, densification occurred during the first stage for three 4 nm particles and during the second stage for four 4 nm particles. Sintering rates obtained here were higher than those obtained by theoretical models generally used for predicting sintering rates of micro-particles.

Large voids created by underground mining are backfilled to provide regional ground support. This thesis examines using conventional oedometer techniques and electromagnetic (EM) techniques to characterize consolidation and binder hydration in mine backfill so that EM monitoring can be used in the field to provide real-time feedback to operators to optimize the backfilling process. New techniques are given for interpreting the full range of deformation (initial compression, primary and secondary consolidation). Deformation due to initial compression is non-trivial and may have to be accounted for in numerical back-analyses of field case studies. EM parameters are sensitive to binder content, progress of hydration and loss of water caused by consolidation and binder hydration. The integrated interpretation of consolidation and EM behaviours has significant potential impact on real-time monitoring of mine backfill operations, and recommendations are made to advance the technique for this purpose.

Large voids created by underground mining are backfilled to provide regional ground support. This thesis examines using conventional oedometer techniques and electromagnetic (EM) techniques to characterize consolidation and binder hydration in mine backfill so that EM monitoring can be used in the field to provide real-time feedback to operators to optimize the backfilling process. New techniques are given for interpreting the full range of deformation (initial compression, primary and secondary consolidation). Deformation due to initial compression is non-trivial and may have to be accounted for in numerical back-analyses of field case studies. EM parameters are sensitive to binder content, progress of hydration and loss of water caused by consolidation and binder hydration. The integrated interpretation of consolidation and EM behaviours has significant potential impact on real-time monitoring of mine backfill operations, and recommendations are made to advance the technique for this purpose.

The aim of this study was to determine the rheological properties of tahin/pekmez blends at different tahin concentrations (20-32%) and temperatures (35-65 &deg / C) by using a concentric cylinder rotational viscometer. Samples were sheared with seven different rotational speeds at an increasing order. The shear rates (0.75-63.9 s-1) were calculated by the Power-law Approximation method. Tahin/pekmez blends were found to exhibit non-Newtonian, shear thinning behavior at all temperatures and tahin concentrations. The experimental data of apparent viscosity versus shear rate were successfully described by the Power-law model. The model parameters / flow behavior index, n varied in the range of 0.7-0.85, whereas the values for the consistency coefficient, K, were in the range of 282-2547 mPa.sn. Apparent viscosity and consistency coefficient of blends increased with increasing tahin concentration and decreasing temperature. Temperature dependency of K was described by an Arrhenius-type equation. Activation energies (Ea) of the blends appeared in the range of 13376-28592 J/mol as the tahin concentration was increased from 20% to 32%. The effect of temperature on n was found to be significant but did not follow any descriptive trend. The relationship between K and tahin concentration was explained by exponential and power functions while tahin concentration had no significant effect on flow behavior index. Power function was found to be superior in explaining the variation of Ea with tahin concentration. A mathematical model was formulated to determine the combined effect of temperature, tahin concentration and shear rate on apparent viscosity.

Antibiotic use is a vital method for the treatment of most diseases involving bacterial infections. Unfortunately, in certain cases these agents are not effective in treatments against diseases for either some limitation in antibiotic usage because of the side effects or some distribution problems caused by physiological or pathological barriers in the body. Such problems are thought to be minimized by development of controlled release systems which involve implantation of antibiotic loaded polymeric systems directly to the site of infection. Present study involves Vancomycin, a very strong antibiotic with a wide spectrum of activity, and two biocompatible and biodegradable polymers, poly(3-hydroxybutyrate-co-3-valerate) PHBV and poly(L-lactide-co-glycolide) PLGA, in the construction of rod shaped controlled release systems designed for the aim of local treatment of osteomyelitis. Vancomycin carrying rods of either PHBV 8 or PLGA (50:50) polymers were prepared by the use of cold paste and hot extrusion methods in two different loading ratios (2:1 and 1:1 P:V). In situ release kinetics of each type of rod was determined by spectrophotometric measurement of vancomycin concentration. For determination of drug content of the controlled release rods initially and at the end of the release experiments, extraction and IR (infrared) studies were carried out. The efficacy of the system was measured in vitro on the bacterial strain, B. subtilis. Characterization of the rods was made by the use of stereomicroscopy and SEM (scanning electron microscopy). In situ release results of the controlled Vancomycin release formulations revealed that for both polymer types, hot extrusion process enabled the formation of a more compact system that provided slower release of the agent compared to the cold paste method. With the combined effect of variable loading proportion and polymer type the most prolonged release was obtained by PHBV rods having 2:1, P:V, ratio (prepared by hot extrusion method). In general, the release kinetics from the rods obeyed the Fickian diffusion kinetics except for PLGA rods prepared by cold paste method with 1:1 and 2:1 (P:V) loading ratios, which had a first order rate of drug release. According to in vitro bioactivity assays, all the groups effectively inhibited bacterial growth with the first day release samples. On the seventh day, however, only two cold paste samples, PHBV:Vancomycin 1:1 and PLGA:Vancomycin 1:1 had drug content barely sufficient for MEC while the others were in the ineffective range. The IR and grinding-extraction studies proved that Vancomycin was still present within the rods after a ten day release period. The PHBV rods with 2:1 (P:V) ratio prepared by hot extrusion method seem to be the most promising drug delivery system in terms of providing prolonged release as an implantable drug delivery system for the treatment of bacterial infections of the bone, namely osteomyelitis.

The objective of this research is the pursuit of a better characterization method for the air voids - particularly air-entrained voids - in fresh cement-based materials through the use of ultrasonics. The use of air-entraining agents (AEA's) to incorporate a stable network of air voids into fresh cement paste is common practice in the concrete industry. These particular air voids significantly improve durability of hardened cement paste through mitigation of stresses associated with freezing and thawing cycles. It is understood that the performance of entrained air voids in cement paste is dependent on their size and distribution, or spacing factor. However, conventional methods for qualifying air content, such as the Pressure, Volume, and Gravimetric Methods, only measure total air volume and cannot assess size or spacing. In this investigation, using matched pairs of transducers, ultrasonic pulses were transmitted through fresh cement paste specimens (0.0\% up to 0.6\% AEA by weight of cement). The received signals were recorded every five minutes during the first six hours and then every fifteen minutes thereafter. Analysis shows strong distinctions between specimens with and those without the AEA. Further research is needed into the distinctions among specimens with the AEA. However, the data suggest correlations between Vicat setting times, heat of hydration, and autogenous strain and ultrasonic metrics such as pulse velocity and peak frequency of the signal. The findings of this research should be most appropriate as a foundation for an inversion process and improved air-entrainment detection methods.