Friction Bit Joining (FBJ) is a new technology used primarily in joining dissimilar metals. Its primary use has been focused in the automotive industry to provide an alternative joining process to welding. As automotive manufacturing has continually pushed toward using dissimilar materials, new joining processes have been needed to replace traditional welding practices that do not perform well when materials are not weld compatible. FBJ meets these needs perfectly as it provides strength as well as the ability to join materials of almost any kind.The purpose of this research was to explore different applications of the FBJ process. Traditionally FBJ has used a steel bit to drill through a thin piece of aluminum and weld to a piece of steel behind the aluminum. This research explored a different application of FBJ by using a steel bit to drill through multiple pieces of aluminum and weld to a small steel bit on the backside of the aluminum. The primary goal of this research was to answer two questions. (1) How does drilling impact peak weld strength and (2) Does an optimal shank diameter exist in terms of peak weld strength? As in other research, no universal parameters were found for optimization of lap shear, cross tension and t-peel tests. Drilling was found to be an important factor in peak weld strength. Number of flutes on the consumable steel bit was varied to see the impact of better and worse chip clearance ability. Increasing number of flutes was found to positively impact peak weld strength to a point. Optimal number of flutes was found to be different for each type of testing. It was found that there was an optimal bit head to bit shank diameter ratio that optimized peak weld strength. Again the optimal diameter was different for each test. Bits of different diameters were created and then tested to measure the impact of varying shank diameters on peak weld strength. It was found that there was a strength tradeoff between two localized joint areas in diameter testing. Decreasing the shank diameter increased the amount of overlap formed by the bit head over the top coupon. This shifted strength to the bit head region. While this strengthened the bit head region of the joint, strength was sacrificed in the bit-nut intersection. This tradeoff was consistently found in all test types.

Pervasive computing is an emerging concept that thoroughly brings computing devices and the consequent technology into people's daily life and activities. Most of these computing devices are very small, sometimes even "invisible", and often embedded into the objects surrounding people. In addition, these devices usually are not isolated, but networked with each other through wireless channels so that people can easily control and access them. In the architecture of pervasive computing systems, these small and networked computing devices form a wireless infrastructure layer to support various functionalities in the upper application layer.;In practical applications, the wireless infrastructure often plays a role of data provider in a query/reply model, i.e., applications issue a query requesting certain data and the underlying wireless infrastructure is responsible for replying to the query. This dissertation has focused on the most critical issue of efficiency in designing such a wireless infrastructure. In particular, our problem resides in two domains depending on different definitions of efficiency. The first definition is time efficiency, i.e., how quickly a query can be replied. Many applications, especially real-time applications, require prompt response to a query as the consequent operations may be affected by the prior delay. The second definition is energy efficiency which is extremely important for the pervasive computing devices powered by batteries. Above all, our design goal is to reply to a query from applications quickly and with low energy cost.;This dissertation has investigated two representative wireless infrastructures, sensor networks and RFID systems, both of which can serve applications with useful information about the environments. We have comprehensively explored various important and representative problems from both algorithmic and experimental perspectives including efficient network architecture design and efficient protocols for basic queries and complicated data mining queries. The major design challenges of achieving efficiency are the massive amount of data involved in a query and the extremely limited resources and capability each small device possesses. We have proposed novel and efficient solutions with intensive evaluation. Compared to the prior work, this dissertation has identified a few important new problems and the proposed solutions significantly improve the performance in terms of time efficiency and energy efficiency. Our work also provides referrable insights and appropriate methodology to other similar problems in the research community.

No description available.

Information technology almost became the savior for Hong Kong in the process of recovering from the Asian financial crisis immediately after the Handover. The claims to establish and further the development of information technology were made against a certain perception of Hong Kong, in which the place in past decades had indulged in the wrong direction of labour-intensive, cut-throat production in the manufacturing industries and bubble-like speculation in the real-estate sector, and against a certain vision of the future, with more and more competition in the age of globalization, neo-liberal economies, and so on. This thesis demonstrates, firstly, how the governance of Hong Kong can be seen from the perspective of contingent articulations of dissimilar elements rather than any step-by-step progression along any necessary, objective historical path. Secondly through analyses of the governmental discourses and the business trajectory of Pacific-Century CyberWorks, the flagship group for Hong Kong’s “new-economy”, the thesis depicts the complexity and nexus of knowledge, governance, bureaucratic and financial considerations of and within the project of information technology in Hong Kong, and the mechanism by which this particular discourse is produced and circulated. Finally, comparing the discourse of Hong Kong’s early industralisation in the early 1950s, the thesis identifies the desire-creating workings of ideology in this particular discourse of information technology in Hong Kong. Also, through theoretical prisms, the thesis provides examples of how the government’s trumpeted notions of (and, probably, people’s faith in) laissez-faire, positive non-intervention are able to coexist in apparent harmony with the highly active participation of the Hong Kong SAR government in society and industry.

No description available.

Visitors use and understanding of interactive exhibits and their learning of scientific concepts was investigated by three studies. The first study categorised visitors' use of a sound exhibit and found that 49% successfully used the exhibit. Understanding was described with a knowledge hierarchy and learning was measured using a pre-test and post-test. Findings indicated that many visitors had prior knowledge of the relevant concepts and 50% of visitors learnt a concept from the exhibit. The second study investigated young children's understanding and interaction with the Mitey Quarry, a cooperative exhibit of four elements, conveyor, elevator, auger and sorter, which were used to move balls around the exhibit. Findings indicated that children's activities and their level of understanding varied for each element, though higher levels were achieved with elements that were easily observable. The children's activities began with observation, and then vacillated between manipulation, operation and control of an element. The third study identified the educational objectives of a physical fitness exhibit, Let's Get Physical, and their achievement by high school students. Findings indicated that the instructional sequence integrated cognitive and affective objectives, and although 42% of students stated their intentions to begin new exercise activities in response to the exhibit message "to be active everyday", after two weeks, these intentions had not been enacted. The research has contributed to improved exhibit design by demonstrating the value of knowledge, activity and affective hierarchies in identifying exhibit objectives and providing a means for evaluation. Hierarchies are an effective way to describe and measure the visitors' use and understanding of interactive exhibits and learning from them.

Starch is a mixture of two polysaccharides, amylose (AM) and amylopectin, which occurs naturally in the form of microscopic granules that are abundantly found in tubers, roots, cereal grains and fruits. In order to bring out their functional properties as thickeners and texture enhancers, starch granules are often disrupted by heating in excess water. This process, which is referred to as gelatinisation, causes the granules to swell and exude a fraction of the starch polysaccharides, resulting in a dramatic increase in the viscosity of the starch suspension. Surfactants are known to affect the different aspects of the gelatinisation process and, in particular, the swelling properties of starch. Surfactants are also known to form helical inclusion complexes with AM, the formation of which plays an important role in many of the instances in which starch and surfactants interact. This work was carried out in order to gain insight into how the surfactant structure (head group and chain length) influences the swelling properties of starch and the molecular mechanisms behind these effects. The investigations involved the study of the temperature-induced gelatinisation of starch in the presence of surfactants as well as studies on the association of surfactants to AM in solution and the solubility of the resulting AM-surfactant complexes. Information on the extent of granule swelling upon heating was indirectly obtained by means of viscometry while insight on the molecular events taking place during gelatinisation was sought by means of differential scanning calorimetry (DSC) and confocal laser scanning microscopy (CLSM). Viscometric studies revealed that, with the exception of the cationic surfactants (alkyl trimethyl ammonium bromides), short-chain (C10, C12) surfactants induce an early swelling (swelling at lower temperatures than the control sample) in normal wheat starch granules, whereas their longer chain counterparts (C14, C16) have the opposite effect. Contrary to this finding, the effect of surfactants on the swelling of waxy wheat starch granules, an AM-free starch variety, is not influenced by the surfactant chain length but by the head group charge of the surfactant. The enhancing/restricting effect of surfactants on the swelling of normal wheat starch is not correlated to their effect on the early aspects of gelatinisation (onset of the gelatinisation transition) but is, in most cases, associated with the dissociation temperature of AM-surfactant complexes formed simultaneously as the granules gelatinise. CLSM studies revealed that, compared to a longer-chain surfactant (C16), a short-chain (C12) surfactant has the ability to penetrate further into the granule matrix during gelatinisation, which may favour its availability for interacting with different starch granule components during gelatinisation. Studies on the interactions between AM and surfactants with different chain length (C12 vs. C16) and head group (sodium sulphates vs. maltosides) revealed that the presence of a charged head group favours the water solubility of the resulting AM-surfactant complexes. However, this effect can be counteracted by the effect of the surfactant chain length: an increase in the chain length (C12 vs. C16) decreases the solubility of the complex. / QC 20100913

The following essay or thesis is a study over scientific endeavors in the fringe. It is a study of Riksorganisationen UFO-Sverige, whose proponents aim to make the UFO phenomenon (or phenomena) a subject of scientific scrutiny. To achieve this, the ufologists first have to redefine common concepts of ufology as pseudo science or religion, mainly by challenging definitions given by scientific sceptics on the one hand, and proponents of conspiracy theories or the new age environment on the other. Thus UFO-Sverige seeks to construct an alternative scientific identity in contrast to adversaries on both sides, each unwilling to give the UFO phenomenon any further examination. Following the work of Tomas Gieryn's sociological grip on questions of epistemology, especially concerning the social boundaries of science from other cultural categories through what has been labelled as epistemic boundary work, during which proponents of a particular field aim to achieve epistemic authority and thus the legitimate right to define what is and what is not science, I seek to analyze how questions of science and legitimacy are actualized in an intellectual environment or culture not broadly accepted as scientific. The essay is a case study of a given organization in the ufologic subculture, analyzing material mainly from the 1990's, and the manner in which epistemic boundary work is made explicit. I further hint at the end to which the boundary work is means, which is mainly the hope of a growing professionalization of the ufologic field. Through this I further argue that the study points at something general, namely the importance of questions of science and legitimacy outside the boundaries of conventional science, not the least for those who are usually denied the recognition of scientific legitimacy and its fruits.

The purpose of the study is to analyse an interdisciplinary research (IDR) project in order to identify whatconstitutes a strategy of integration of disciplinary insights. Through interviews, observations andanalysis of scientific articles produced by the researchers, the study explores the processes of IDR andrelates them to psychological and sociological theories of group research. The results show thatresearchers employ an emergent strategy which they design ad hoc, and which consists of certain patternsof behaviour that allow them to navigate conflict and partially integrate their insights into the problem.The study offers a number of recommendations that might be useful to take into consideration whendesigning an IDR project.

Over the last decade, considerable research interest has peaked in realizing an efficient Terahertz (THz) waveguide for potential applications in imaging, sensing, and communications applications. Two of the promising candidates are the two-wire waveguide and the parallel-plate waveguide (PPWG). I present theoretical and experimental evidence that show that the two-wire waveguide supports low loss terahertz pulse propagation, and illustrate that the mode pattern at the end of the waveguide resembles that of a dipole. In comparison to the weakly guided Sommerfeld wave of a single wire waveguide, this two-wire structure exhibits much lower bending losses. I also observe that a commercial 300-Ohm two-wire TV-antenna cable can be used for guiding frequency components of up to 0.2 THz, although these cables are generally designed to operate only up to about 800 MHz. The parallel-plate waveguide is another promising candidate that would make an efficient THz waveguide, since it has relatively low Ohmic losses. The transverse electromagnetic mode (TEM) of this waveguide has been generally preferred since it has no cutoff frequency, and therefore no group velocity dispersion. Utilizing this TEM mode, I study the reflection of THz radiation at the end of a PPWG, due to the impedance mismatch between the propagating transverse-electromagnetic mode and the free-space background. I find that for a PPWG with uniformly spaced plates, the reflection coefficient at the output face increases as the plate separation decreases, consistent with predictions by early low frequency ray optical theory. I observe this same trend in tapered PPWGs, when the input separation is fixed, and the output separation is varied. In another study, I investigate how to minimize diffraction losses in PPWGs by using plates with slightly concave surfaces. Using a simple “bouncing plane wave” analysis, I demonstrate how to determine an ideal radius of curvature for a waveguide operating at a given THz frequency. I perform a detailed experimental and simulation study that illustrates, for a waveguide with a plate separation of 1 cm, one can inhibit the diffraction around a frequency of 0.1 THz, when the surface has a curvature of 6.7 cm. Using much longer PPWGs (about 170cm), I reliably measure the overall losses in a PPWG with a radius of curvature of R=6.7 cm, and find it to be less than 1db/m around the design frequency (of 0.1 THz). This is very close to the lowest achieved loss to date with any terahertz waveguide.