No description available.

The availability of sophisticated machine tools, together with advanced cutting tool designs and high performance coatings has allowed machining to meet many challenges. A significant remaining challenge is the competitive milling of hardened steels at moderate to high cutting speeds. This is of particular importance for the die and mould making industry. Despite the necessity to achieve higher production rates and improved surface finish, cutting speeds above the range of 300-600 m/min are still not possible. This limitation is due to the combination of high mechanical, thermal and chemical interactions that are taking place on the tool surface during cutting. To address this situation, an extensive amount of research has been focused on developments associated with hard coatings such as nano-multilayered hard PVD coatings that exhibit novel mechanical and thermal properties. The development of methodologies for designing a cutting tool with a strong cutting edge micro-geometry has set guidelines for selecting proper cutting edge preparation for specific cutting applications. The results indicate that, the development of new hard coating designs is the most effective way to improve the service life of coated carbide tools for hard high speed milling applications. The developments of both robust and rigid substrate designs with adaptive cutting edge micro-geometries assist the cutting tool performance by favoring the surface adaptability of the deposited coating. The developments of different strategies for dry air cooling that provide a "soft-cool" environment seem to have a beneficial impact on cutting performance and tool life improvement. Dry air cooling is found to be more effective than chilled-air cooling and minimum-quantity-lubrication (MQL). Therefore, the utilization of a cutting environment tailored to meet the requirements of both the tool and the coating while providing sufficient air flow to remove chips from the cutting zone will complement the adaptability of the whole tool-workpiece-chip system. / Thesis / Master of Applied Science (MASc)

No

Yes / Cementitious composites, the most abundant human-made materials in the world, are challenged to be more sustainable, durable and cost-effective to adapt to the development of structural engineering, economy and environment. Owing to their excellent strength, toughness and durability, nano-fillers reinforced cementitious materials have attracted broad attention in civil engineering researches and applications. However, it is worth noting that nano-fillers reinforced cementitious materials achieve their proprieties by using of different industrial nano-fillers, i.e., graphenes, carbon nanotubes, carbon nanofibers, etc. Although the properties of conventional cementitious materials are improved, the incorporation of the above nano-fillers are high cost and environmental footprint. Different from high-energy consuming carbon nanofillers, nanocellulose is one of the biomass-derived nanofillers with excellent nanometer properties, biological performances and composite effects, and it has proved to be a promising green filler to enhance the mechanical properties, durability and functional properties and lower the carbon footprint of cementitious composites. Therefore, this paper provides an overview on biomass-derived nanocellulose modified cementitious composites, mainly focusing on their fabrication, properties (early performance, mechanical performance, durability, and functional performance) and applications. It also concludes with an outline of some future opportunities and challenges in the development of biomass-derived nanocellulose modified cementitious composites.

Memory forensics (or memory analysis) is a relatively new approach to digital forensics that deals exclusively with the acquisition and analysis of volatile system memory. Because each function performed by an operating system must utilize system memory, analysis of this memory can often lead to a treasure trove of useful information for forensic analysts and incident responders. Today’s forensic investigators are often subject to large case backlogs, and incident responders must be able to quickly identify the source and cause of security breaches. In both these cases time is a critical factor. Unfortunately, today’s memory analysis tools can take many minutes or even hours to perform even simple analysis tasks. This problem will only become more prevalent as RAM prices continue to drop and systems with very large amounts of RAM become more common. Due to the volatile nature of data resident in system RAM it is also desirable for investigators to be able to access non-volatile copies of system RAM that may exist on a device’s hard drive. Such copies are often created by operating systems when a system is being suspended and placed into a power safe mode. This dissertation presents work on improving the speed of memory analysis and the access to non-volatile copies of system RAM. Specifically, we propose a novel memory analysis framework that can provide access to valuable artifacts orders of magnitude faster than existing tools. We also propose two new analysis techniques that can provide faster and more resilient access to important forensic artifacts. Further, we present the first analysis of the hibernation file format used in modern versions of Windows. This work allows access to evidence in non-volatile copies of system RAM that were not previously able to be analyzed. Finally, we propose future enhancements to our memory analysis framework that should address limitations with the current design. Taken together, this dissertation represents substantial work towards advancing the field of memory forensics.

M. Tech. (Biomedical technology, Faculty of Applied and Computer Science), Vaal University of Technology / Approximately 1% of the world’s population has epilepsy, the second most common neurological disorder after stroke. In South Africa almost 1 in every 100 people has epilepsy, affecting all ages. Levetiracetam (LEV), marketed as Keppra® is an anticonvulsant drug used in the treatment of epilepsy. The daily dosage is 500 mg twice daily with a maximum of 3000 mg. The therapeutic range of LEV is between 12-46 μg/ml. Therapeutic drug monitoring (TDM) should be considered for LEV in patients with poor seizure control or long term treatment. TDM depends on accurate drug concentration measurements. In order to provide an accurate measurement, the High performance liquid chromatography (HPLC) method was developed, compared with a commercially available kit, and the stability of the samples was investigated. Ethical approval was obtained from the Human Research Ethics Committee (Medical), VUT (Ethics reference number: 2015024.4). The study was conducted from January to October 2015. This study involved three groups of volunteers who gave written consent. The first group were fifteen healthy MTech students in the Biomedical Technology Department at the Vaal University of Technology (VUT). Their blood samples were used for the analytical validation of the method and for the stability studies over a 4 weeks period. The second group were six patients from Pathcare Laboratories in Potchefstroom, Klerksdorp and Vereeniging who used Levetiracetam. Their blood samples were used to investigate the influence of different collection tubes as well as the handling and storage of samples on the LEV concentration. The third group were forty four patients from Pathcare Laboratories, Cape Town. Their blood samples were transported to Clinical Pharmacokinetic Laboratory (CPL) for routine therapeutic drug monitoring analysis of LEV and used to compare the newly developed HPLC method and the Commercial kit. The HPLC method was successfully developed and validated to determine LEV in human plasma/serum samples. The calibration curves showed good linearity (r2 = 0,999) over the concentration range of 1 – 60 μg/ml. Accuracy, mean extraction recovery, lower limit of detection (LLOD) and lower limit of quantification (LLOQ) were 98-112%, 97,15% (±1,57), 0,5 and 1,0 μg/ml respectively, in plasma standards. The method was shown to be simple and fast, reproducible and effective for routine laboratory analyses in the future. The agreement between the newly developed method and the ClinRep® HPLC complete commercial kit was the same and there was a statistical significant correlation between the two methods (average r=0.999; p-value < 0.0001, F-test with a true value =0). The method was much cheaper than the commercial kit, used less sample (100 μl) and had a longer running time (15 minutes) to ensure no endogenous interference. The costs of the developed method was 71-82% lower than the three commercial kits available in South Africa. Stability experiments were performed to evaluate the stability of LEV in human plasma/serum, simulating the same conditions which occurred during study samples’ analyses. The % RSD was lower than 5% under all the conditions: freeze, fridge, room temperature and auto sampler over the 4 week period. The results showed that both LEV and the I.S (internal standard) were stable in human serum/plasma under all these conditions. The influence of five different collection tubes, Gold (SST Gel), Red, Purple (EDTA)Green (Heparin) and Blue (Sodium Citrate) was investigated. In two patients, decreased levels were observed in tubes containing blue (sodium citrate) and Green (Heparin). The decrease was not statistically significant. This is an important observation and is an indication that anticoagulants may cause some problems due to drug-protein binding and interference in the matrix effect. A cost effective and reliable HPLC-method with minimal sample preparation time for the routine determination of LEV in plasma/serum samples was developed. It was also shown that the plasma/serum samples were stable at different temperatures over a time period. The only collection tubes that may interfere with the concentrations were the Green (Heparin) and Blue (Sodium Citrate) tubes.

High Performance Liquid Chromatography (HPLC) has been employed as an analytical tool for the purification and separation of nucleic acids. A Nucleogen DEAE 4000-10 weak anion exchange column, prepacked with modified silica gels, was used to purify and separate a number of Escherichia coli plasmids. Plasmid DNAs were extracted by the alkaline lysis method. The cleared lysate was injected directly onto the Nucleogen column, and the peaks were collected, desalted and analysed by gel electrophoresis. On the chromatogram, the pBR322 formed a distinctive peak at 27 minutes and partial separation was made for the E. coli V517 plasmids. Plasmid pBR322 showed a clear band without any detectable contamination on agarose gel. This purified plasmid DNA is biologically active for enzymatic reaction commonly used in genetic engineering techniques.

Future supercomputers will require application developers to expose much more parallelism than current applications expose. In order to assist application developers in structuring their applications such that this is possible, new programming models and libraries are emerging, the many-task runtimes, to allow for the expression of orders of magnitude more parallelism than currently existing models. This dissertation describes the challenges that these emerging many-task runtimes will place on performance analysis, and proposes deep integration between runtimes and performance tools as a means of producing correct, insightful, and actionable performance results. I show how tool-runtime integration can be used to aid programmer understanding of performance characteristics and to provide online performance feedback to the runtime for Unified Parallel C (UPC), High Performance ParalleX (HPX), Apache Spark, the Open Community Runtime, and the OpenMP runtime.

Cohesion is essential for team harmony and performance. It is universally sought in sport teams. The benefits have been extensively studied and are a requirement of team success. Counter to wide held belief, cohesion is not an intrinsically positive phenomenon. This thesis aimed to develop more understanding of the potential disadvantages or costs of high cohesion in sport teams to fill a significant gap in the literature. Study 1 examined the extent and nature of these costs. Athletes perceived similar costs. Fourteen categories of costs were identified with perceived pressures and communication issues demonstrated to be strongly significant. Study 2 was framed in narrative theory to explore costs experienced over the life-span career of a retired professional motor sport co-driver. The most significant costs experienced were pressure to perform and pressure to conform. The key influencing factors were a performance narrative along with what was identified as a new narrative type, the team performance narrative. Study 3 utilised the lens of narrative theory to explore when and where costs were not experienced by a current elite motorsport sport driver and his team. Buffers were indicated. Study 4 was a case study of a high performing team where across the entire season team cohesion was high but performance wasn’t reciprocated accordingly. High cohesion produced costs of conformity and normative influence, rigid demands and methods with narrow goal focus, communication issues and pressure to perform. These costs are all inter-related and interacted to have a negative impact on performance. This thesis raises awareness of the potential costs of high cohesion in sport teams and, by offering a new model – the Cohesion Costs’ Reduction Model - for identifying strategies to minimise these potential costs, aims to improve individual wellbeing in a team and improve team performance.

Thesis (Ph. D.)--Pennsylvania State University, 1982. / Includes bibliographical references.