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Modification of Float Glass Surfaces by Ion ExchangeKarlsson, Stefan January 2012 (has links)
Glass is a common material in each person’s life, e.g. drinking vessels, windows, displays, insulation and optical fibres. By modifying the glass surface it is possible to change the performance of the entire glass object, generally known as Surface Engineering. Ion exchange is a convenient technique to modify the glass surface composition and its properties, e.g. optical, mechanical, electrical and chemical properties, without ruining the surface finish of the glass. This thesis reports the findings of two different research tasks; characterisation of the single-side ion exchange process and the novel properties induced. The characterisation of the ion exchange process was mainly performed by utilising a novel analytical equipment: the Surface Ablation Cell (SAC), allowing continuous removal of the flat glass surface by controlled isotropic dissolution. SAC-AAS has provided concentration vs. depth profiles of float glass ion exchanged with K+, Cu+, Rb+ and Cs+. In addition, SEM-EDX has provided concentration vs. depth profiles of Ag+ ion exchanged samples and validation of a copper concentration vs. depth profile. From the concentration vs. depth profiles, the effective diffusion coefficients and activation energies of the ion exchange processes have been calculated. Depending on the treatment time and treatment temperature, penetration depths in the range of 5-10 μm (Rb+, Cs+), 20-30 μm (K+, Cu+) and 80-100 μm (Ag+) can be readily obtained. The effective diffusion coefficients followed the order Ag+>K+>Cu+>Rb+>Cs+. This is in accordance with the ionic radii for the alkali ions (K+<Rb+<Cs+) but reverse for the noble metal ions (Cu+<Ag+). The glass properties modified by single-side ion exchange have mainly been characterised by UV-VIS spectroscopy and flexural strength measurements. Cu+ and Ag+ ion exchange give rise to surface colouration, Cu+ copper-ruby and Ag+ yellow/amber. The surface-ruby colouration was found to depend on the residual tin ions in the tin-side of the float glass. The flexural strength was studied using the coaxial double ring-test method which also was suitable for holed specimens. The flexural strength of K+ ion exchanged float glass samples was found to substantially increase compared to untreated.
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Styrketillväxt med hjälp av vibrationsplattaKriborg, Peter, Kraft, Magnus, Brännberg, Anna, Mathisson, Pierre January 2008 (has links)
Abstract 1. The purpose of this study was to investigate the effects whole body vibrations on maximal strength, power output and neuromuscular activity in m. pectoralis major during bench press. Participants consisted of 35 male and 9 female military high school students (m=23, 1 years). On the basis of initial maximal performances in bench press the participants was divided into two experiments groups and one control group. Intervention groups performed a specifically designed push up program on a vibrating plate respectively a step board during 12 weeks Initial load at 60 % of 1 RM showed an average of 46, 5 kg. All groups showed an average increase of 13 kg for each person after 12 weeks. Initial value for power output showed a mean of 265 watt, which also showed an increase with an average of 7 watt (with a load equivalent of 60 % of 1 RM at the current test occasion), respectively an increase of 41 watt (with the load performed during the first test occasion). A positive correlation existed between the load at 60 % of 1 RM and achieved power output. No significant differences between groups were exposed concerning estimated maximum strength or power output in bench press. All participants showed an increase in strength development, indicating that vibration stimuli could be compared to traditional push ups training without vibrations. Vibrations seem to have more effects on the magnitude of recruited motor units, why vibrations training could be a good complement to established strength training. Abstract 2. The purpose of this study was to investigate the effects whole body vibrations on strength development, power output and neuromuscular activity in m. pectoralis major during bench press. The purpose was also to examine what roll self-efficacy plays in strength tasks. Participants consisted of 35 male and 9 female military high school students (m=23, 1 years). On the basis of initial maximal performances in bench press the participants was divided into two experiments groups and one control group. Intervention groups performed a specifically designed push up program on a vibrating plate respectively a step board during 12 weeks. All participants answered a battery of questionnaires concerning backgrounds, motives for sport participation, self-efficacy and efficacy sources. Initial load at 60 % of 1 RM showed an average of 46, 5 kg (sd = 13, 8). All groups showed an average increase of 13 kg for each person after 12 weeks. Initial value for power output showed a mean of 265 watt, which also showed an increase with an average of 7 watt (with a load equivalent of 60 % of 1 RM at the current test occasion), respectively an increase of 41 watt (with the load performed during the first test occasion). A positive correlation existed between the load at 60 % of 1 RM and achieved power output. No significant differences between groups were exposed concerning estimated maximum strength or power output in bench press. Gender differences showed that men lifted significantly heavier loads at 60 % of 1RM compared to women. No significant differences could be seen between the groups concerning self efficacy. Gender differences were exposed concerning self-efficacy to push ups with a pat. The efficacy sources “performance accomplishments” was valuated to be the most influential to form self-efficacy expectations. A strong positive relationship between “performance accomplishments” and achieved self-efficacy to push ups with pats were shown. Self-efficacy to push ups with a pat also correlated positively with power output and performed 60 % of 1 RM in bench press. All participants showed an increase in strength development, indicating that vibration stimuli could be compared to traditional push ups training without vibrations. Vibrations seem to have more effects on the magnitude of recruited motor units, why vibrations training could be a good complement to established strength training. Participants relatively high self-efficacy to strength tasks is probably a result of performance accomplishments in there own strength straining rather than the intervention training. Positive relationships between self-efficacy and power output as well as performed 60 % of 1 RM in bench press, indicating that high self-efficacy have a positive influence on strength performance. Keywords: estimated maximal strength (1RM), neuromuscular activity, power output, self-efficacy.
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Dynamisk styrketräning av M : Quadriceps femoris hos personer i övre medelåldernKarjalainen, Terese January 2008 (has links)
Abstract Elderly people are going to be a growing number in Europe. Between one third are going to be 60 years or older at 2025. For Sweden the situation is going to be similar. A reduced muscle function could lead to complications for the individual to perform daily tasks and will lead to a higher rate for falling and getting bone fractures. The positive sides are that for men and women there are a possibility for maintaining physical function and strength even in older years. The purpose of this study was to investigate the possibility of gaining strength in M. Quadriceps femoris among five elderly people. The training schedule followed over 6 weeks of time with training sessions twice a week, training the Quadriceps muscle with one set of each training session. The result shows that for the three people that completed the study, all of them managed to gain strength. Further the study examines resistance training comparing single and multiple sets. Is there any difference in gaining strength between training programs with single set training versus multiple sets training?
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RAS measurements of anisotropy in rubbed polyimide thin filmYe, Yi-Jhih 27 July 2007 (has links)
Rubbing alignment is widely used in display industry, Rubbing cause anisotropy in rubbed polyimide thin film influence the alignment of Liquid Crystal.
The major part of this article is to analyze surface optical anisotropy of rubbed polyimide thin film. RAS signals and surface free energies of rubbed polyimide thin film with different rubbing strength are measured, and relationship between anisotropy of surface and rubbing strength is discussed. The mechanism of alignment can be understood by this work.
Reflection Anisotropy Spectroscopy (RAS) has been used in Semiconductor as a tool to monitor crystal growth for many years. RAS is a non-contact and non-destructive measurement method. It only measures the difference of two orthogonal complex reflection signals and optical anisotropy of surface. It¡¦s very sensitive to the anisotropy of surface. In the current studies, RAS has been used to detect surface anisotropy of rubbed polymer.
We measured the surface free energy of the rubbed polyimide thin films. It has been found that surface free energy is of anisotropy due to the application of mechanical rubbing to the polymer surface.
Pretilt angle influences the alignment of liquid crystals. The molecule orientation of PI surface and anisotropy of rubbed PI surface effect pretilt angle¡CPretilt angles measured by pretilt angle measurement system compare with RAS signals.
RAS signals, anisotropy of surface free energies, and pretilt angles are increasing with increasing rubbing strength.
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Carbon nanotube and nanofiber reinforcement for improving the flexural strength and fracture toughness of portland cement pasteTyson, Bryan Michael 2010 May 1900 (has links)
The focus of the proposed research will be on exploring the use of nanotechnology-based nano-filaments, such as carbon nanotubes (CNTs) and nanofibers (CNFs), as reinforcement in improving the mechanical properties of portland cement paste as a construction material. Due to their ultra-high strength and very high aspect ratios, CNTs and CNFs have been used as excellent reinforcements in enhancing the physical and mechanical properties of polymer, metallic, and ceramic composites. Very little attention has been devoted on exploring the use of nano-filaments in the transportation industry. Therefore, this study aims to bridge the gap between nano-filaments and transportation materials. This will be achieved by testing the integration of CNTs and CNFs in ordinary portland cement paste through state-of-the-art techniques. Different mixes in fixed proportions (e.g. water-to-cement ratio, air content, admixtures) along with varying concentrations of CNTs or CNFs will be prepared. Different techniques commonly used for other materials (like polymers) will be used in achieving uniform dispersion of nano-filaments in the cement paste matrix and strong nano-filaments/cement bonding. Small-scale specimens will be prepared for mechanical testing in order to measure the modified mechanical properties as a function of nano-filaments concentration, type, and distribution. With 0.1 percent CNFs, the ultimate strain capacity increased by 142 percent, the flexural strength increased by 79 percent, and the fracture toughness increased by 242 percent. Furthermore, a scanning electron microscope (SEM) is used to discern the difference between crack bridging and fiber pullout. Test results show that the strength, ductility, and fracture toughness can be improved with the addition of low concentrations of either CNTs or CNFs.
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Evaluation of impact of organizational culture in workplace : an empirical study of HandelsbankenChen, Ziyuan, Hua, Dong January 2008 (has links)
A well established organization culture is necessary for the success of a company. In this study, we choose Handelsbanken to demonstrate how an international company develops its culture, and find out what are the important characteristics of that culture. It was concluded that a successful company must have a well established organization culture, which can not only adapt to different outside environment but also bring solidarities in organizations. Further more, there is no culture is better or worse, there is only the culture that is most appropriate and efficient for the company. This thesis demonstrates how an international company develops its culture, therefore, it will be valuable for those who want to create or improve their organization cultures.
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Jet impingement boiling heat transfer at low coiling temperaturesChan, Phillip 05 1900 (has links)
The production of advanced high strength steels (AHSS) for use in the automotive and construction industries requires complex control of runout table (ROT) cooling. Advanced high strength steels require coiling at temperatures below 500 °C in order to produce a complex multi-phase microstructure. The research described here will investigate the boiling conditions that occur for moving plate experiments when steel is cooled towards low coiling temperatures.
Experiments were performed on a pilot-scale ROT located at the University of British Columbia using industrially supplied steel plates. Tests were performed for four different speeds (0.3, 0.6, 1.0 and 1.3 m/s) and three different initial plate temperatures(350, 500 and 600 °C). Each plate was instrumented with thermocouples in order to record the thermal history of the plate.
The results show that cooling is more effective at slower speeds within the stagnation zone for surface temperatures over 200 °C. Outside the stagnation zone regardless of speed cooling is primarily governed by air convection and radiation with minor effects from latent heat caused by splashing water. The maximum peak heat flux value increases with decreasing speed and occurs at a surface temperature of approximately 200 °C, regardless of speed. Below a surface temperature of 200 °C, speed has a negligible effect on peak heat flux. The maximum integrated heat flux seems to vary with speed according to a second order polynomial.
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Light Weight and High Strength Materials Made of Recycled Steel and AluminumNounezi, Thomas 10 January 2012 (has links)
Recycling has proven not only to address today’s economical, environmental and social issues, but also to be imperative for the sustainability of human technology. The current thesis has investigated the feasibility of a new philosophy for Recycling (Alloying-Recycling) using steel 1020 and aluminum 6061T6. The study was limited to the metallurgical aspects only and has highlighted the potential of recycled alloys made of recycled aluminum and steel to exhibit substantially increased wear resistance and strength-to-weight ratio as compared to initial primary materials. Three alloy-mixtures are considered: TN3 (5wt% 1020 +95wt% 6061T6); TN5 (0.7wt% 1020 + 99.3wt% 6061T6); and TN4 (10wt% 6061T6 + 90wt% 1020). A Tucker induction power supply system (3kW; 135-400 kHz) is used to melt the alloy mixtures for casting in graphite crucibles. Heat treatment of the cast samples is done using a radiation box furnace. Microscopy, Vickers hardness and pin-on-disc abrasive wear tests are performed.
Casting destroyed the initial microstructures of the alloys leading to a hardness reduction in the as-cast and solution heat-treated aluminum rich samples to 60 Hv from 140 Hv. Ageing slightly increased the hardness of the cast samples and provided a wear resistance two times higher than that of the initial 6061T6 material. On the steel rich side, the hardness of the as-cast TN4 was 480 Hv, which is more than twice as high as the initial hardness of steel 1020 of 202 Hv; this hints to strong internal and residual stress, probably martensite formation during fast cooling following casting. Solution heat treatment lowered the hardness to the original value of steel 1020, but provided about ten (10) times higher wear resistance; this suggests higher ductility and toughness of normalised TN4 as compared to 1020. In addition, TN4 exhibits about 25% weight reduction as compared to 1020.
The actual recycling process and the effect of non-metallic impurities shall be investigated in future works. Also, the casting and heat treatment processes need to be improved.
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Cooperative localization based on received signal strength in wireless sensor networkZheng, Jinfu 01 January 2010 (has links)
Localization accuracy based on RSS (Received Signal Strength) is notoriously inaccurate
in the application of wireless sensor networks. RSS is subject to shadowing effects, which is signal attenuation caused by stationary objects in the radio propagation. RSS are actually the result of decay over distances, and random attenuation over different directions. RSS measurement is also affected by antenna orientation. Starting from extracting the statistical orders in the function relationship between RSS and distance, this thesis first shows how non-metric MDS (Multi-Dimensional Scaling) is the suitable method for cooperative localization. Then, several issues are presented and discussed in
the application of non-metric MDS, including determining full connections to avoid flip
ambiguities, leveraging the proper initial estimation to avert from local minimum
solutions, and imposing structural information to bend the localization result to a priori knowledge. To evaluate the solution, data were acquired from different scenarios including accurate radio propagation model, indoor empirical test, and outside empirical test. Experiment results shows that non-metric MDS can only combat the small scale randomness in the shadowing effects. To combat the large scale ones, macro-diversity approaches are further presented including rotating the receiver’s antenna or collecting RSS from more than one mote in the same position. By averaging the measurements from these diversified receivers, simulation results and empirical tests show that shadowing effects can be greatly reduced. Also included in this thesis is how effective packet structures should be designed in the mote programming based on TinyOS to collect different sequences of RSS measurements and fuse them together. / UOIT
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Correlation between physical properties and flowability Indicators for fine powdersBodhmage, Abhaykumar Krishnarao 03 July 2006
Approximately 80% of pharmaceutical products and the ingredients required for their manufacture are in powder form. The solid dosage form (tablets and capsules) is manufactured by either dry-blending of fine powder ingredients or combining the ingredients in a wet granulation step, followed by drying. Arching, ratholing, caking, segregation and flooding are some of the commonly encountered flow problems in the handling of fine powders. These problems lead to losses worth thousands of dollars at production scale. Poor powder flowability is a consequence of the combined effects of many variables, including improper equipment design, particle size, size distribution, shape, moisture content and surface texture. In the present work, a systematic study has been performed to determine the relationship between the flowability of fine powders and their physical properties of mean size and size distribution, density and shape.<p> Flowability studies were done on six different powders: the NutraSweet® Brand sweetener (aspartame), Respitose ML001, Alpha-D-Lactose monohydrate, the pharmaceutical binder Methocel (R) F50 Premium Hydroxypropyl methylcellulose- HPMC, a placebo pharmaceutical granulate, and common pastry flour. Scanning electron microscopy (SEM) and stereomicroscopy were used for particle shape and size analysis. Particle size distribution was determined using the laser light scattering technique. Powder flowability was measured using shear strength, angle of repose, and tapped-to-bulk density measurements. A novel method of measuring the dynamic angle of repose using electrical capacitance tomography (ECT) was developed. <p> Analysis of the images from microscopy revealed that the particles of aspartame and HPMC powders were elongated, the particles of ML001, pastry flour and lactose monohydrate powders were irregular, and the particles of placebo granulate were nearly spherical. Particle size was found to be the most reliable indicator of powder flowability, with decreasing particle size corresponding to lower flowability; however other parameters such as particle elongation and irregularity, were also found to have an influence on powder flowability. Although HPMC and pastry flour had similar particle sizes, they exhibited differences in flowability. This can be explained by the greater irregularity of the flour particles. Particle irregularity may cause mechanical interlocking between the particles, thus reducing powder flowability. ECT was found to be a promising non-intrusive tool for the measurement of the dynamic angle of repose. Unlike other methods for the measurement of dynamic angle of repose, the results obtained from ECT were not influenced by the effect of end caps. The present technique could be used by pharmaceutical industries in process analytical technology (PAT) for the detection and elimination of potential flow problems early in the manufacturing process.
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