Metal evaporated tape: state of the art and prospects

Thin metallic films are the first choice for media in advanced rigid disk systems. For helical scan tape recorders thin metal films have become more important. The high signal-to-noise ratio per unit of track width allows very high densities. The preparation techniques and materials properties of the thin-film coating of metal evaporated (ME) are described. Important aspects are the size of the grains, the geometry of the columnar structure and the associated anisotropy. The consequences for the recording process are explained. Tribological and corrosion properties also help to determine the usefulness of a recording tape. Corrosion, wear, protection layers and lubricating organic films are briefly discussed

Doctor of Philosophy

dissertationSolutions to Partial Di erential Equations (PDEs) are often computed by discretizing the domain into a collection of computational elements referred to as a mesh. This solution is an approximation with an error that decreases as the mesh spacing decreases. However, decreasing the mesh spacing also increases the computational requirements. Adaptive mesh re nement (AMR) attempts to reduce the error while limiting the increase in computational requirements by re ning the mesh locally in regions of the domain that have large error while maintaining a coarse mesh in other portions of the domain. This approach often provides a solution that is as accurate as that obtained from a much larger xed mesh simulation, thus saving on both computational time and memory. However, historically, these AMR operations often limit the overall scalability of the application. Adapting the mesh at runtime necessitates scalable regridding and load balancing algorithms. This dissertation analyzes the performance bottlenecks for a widely used regridding algorithm and presents two new algorithms which exhibit ideal scalability. In addition, a scalable space- lling curve generation algorithm for dynamic load balancing is also presented. The performance of these algorithms is analyzed by determining their theoretical complexity, deriving performance models, and comparing the observed performance to those performance models. The models are then used to predict performance on larger numbers of processors. This analysis demonstrates the necessity of these algorithms at larger numbers of processors. This dissertation also investigates methods to more accurately predict workloads based on measurements taken at runtime. While the methods used are not new, the application of these methods to the load balancing process is. These methods are shown to be highly accurate and able to predict the workload within 3% error. By improving the accuracy of these estimations, the load imbalance of the simulation can be reduced, thereby increasing the overall performance

Magnetization transitions obtained by deconvolution of measured replay pulses in perpendicular magnetic recording

Magnetization transitions in perpendicular magnetic recording have been calculated from measured replay pulses by a deconvolution algorithm using an analytical expression for the field of a probe head (PH). The transitions appear to be asymmetric whereby a pronounced magnetization peak occurs whose shape depends on the medium coercivity. For the experiments double layer media with double sided probe heads have been used. For the deconvolution only perpendicular head field and medium magnetization components are considered

Comparison of recording properties of ME tape and thin MP tape with respect to overwrite behavior

Differences between the recording characteristics of thin MP and ME tape are studied. The effect of the thickness reduction of MP tape is also investigated. When thin MP tape (with thickness 140 nm) is compared with ME tape (with thickness 150 nm), we observe a better signal and overwrite response for the ME tape. Through simulations the influence of an easy axis out-of-plane and a different reversal mechanism in ME tape is related to overwrite behavio

Track edges in metal-evaporated tape and thin metal-particle tape

MFM images of tracks written in ME and MP tape have been obtained. The analysis of the images concentrated on the track edges. A track written with signals of 0.5 μm wavelength overwrites a part of a track written with a wavelength of 1 μm. The sharpness of the edges was derived from MFM results. It can be seen that the MP sample shows smaller changes in sharpness of the edge with an increasing write current than ME tape. In ME tape, the region between the λ=0.5 μm and the λ=1 μm parts of the track is much wider than the original λ=1 μm edge

Latest advancements in process intensification to support global demand for affordable vaccines

Vaccines have a profound impact on global health, preventing illness, death, and improving the quality of life across the globe. However, the current costs of vaccine manufacturing and distribution often prevent the poorest segments of the world’s population from accessing these critical medicines. Vaccine manufacturing for global distribution typically requires large and expensive manufacturing facilities that result in high vaccine Cost of Goods and impede developing countries from initiating or expanding in-country manufacturing capabilities. One of the strategies to address this is to intensify vaccine production processes. This presentation will give an overview of a project funded by the Bill & Melinda Gates foundation that focusses on applying the latest process intensification technologies to develop a platform that dramatically increases process efficiency, decreases production scale and reduces vaccine COGs to a price of $0.15 per dose or less. This vaccine manufacturing platform combines Vero cell lines optimized for virus propagation and media capable of supporting high cell density cell growth, high cell density single-use bioreactors and high efficiency and single step purification technologies. Together, these technologies enable vaccine yields to be significantly increased, which in turn allows commercial manufacturing in a small-footprint, low cost “micro-facility” capable of delivering \u3e40M doses of vaccine per year for a CAPEX of not more than$10M and low operational costs. Such “micro-facilities” can be rapidly and inexpensively commissioned, drastically reducing vaccine COGs, facilitating rapid response and resulting in commercial manufacturing at lab scale. The platform is currently being established using Sabin IPV as the target vaccine. Current status is that Vero cell lines expressing 2-4 fold higher cell specific virus titers have been selected. These have been successfully cultured in high cell density, single-use bioreactors up to 40 million cells per mL. Following infection with Sabin poliovirus vaccine strains, a single chromatographic step using a novel membrane has resulted in 90% recoveries at 95% purity. For IPV, these yield intensifications mean that the entire commercial scale process can be operated in isolators in a footprint of ±30 m2. Combination of four of these manufacturing units in a single “micro-facility” would be capable of delivering \u3e40 million doses of trivalent sIPV per year. Performance of the manufacturing process in isolators also allows the manufacture of viral vaccines that currently require high biological safety containment in an inexpensive facility design. This presentation will discuss the technologies used in the vaccine manufacturing platform and data obtained to date on Sabin IPV in more detail

Leg Strength and Vertical Jump of Basketball Players as Affected by Two Select Exercise Programs Conducted Throughout the Competitive Season

The purpose of this study was to determine the effects of two varying training programs, weight training and Exer-Genie training. Upon the leg strength and explosive power of high school basketball players. The training programs were carried on during the competitive basketball season. The twenty-two members of the De Smet High School basketball squad for the year 1967-1968 were selected for this study. The subjects were divided into two equated groups, according to results in the Sargent Jump Test. Groups were randomly designated. Group A participated in a 12 week weight-training program, consisting of three circuits of two exercises, three times per week. Group B trained with the Exer-Genie in a similar manner for 12 weeks. All subjects were tested before the training, every three weeks during the training, and one and two weeks after the conclusion of the training period. Leg strength and explosive power were tested. The data collected during ·the testing were recorded and analyzed to determine what effect the two training programs had upon leg strength and explosive power. A comparison was made between the two training groups; from this comparison no statistical significance was found between groups. But, there was a statistically .significant increase in both leg strength and explosive power within each group. The results of this study indicated that either weight training or Exer-Genie training could significantly increase leg strength and explosive power during the competitive basketball season