Routing messages between pairs of nodes is one of the most fundamental tasks in any distributed computing system. An Interval Routing Scheme (IRS) is a well-known, space-efficient routing strategy for routing messages in a network. In this scheme, each node of the network is assigned an integer label and each link at each node is labeled with an interval. The interval assigned to a link l at a node v indicates the set of destination addresses of the messages which should be forwarded through l at v. When studying interval routing schemes, there are two main problems to be considered: a) Which classes of networks do support a specific routing scheme? b) Assuming that a given network supports IRS, how good are the paths traversed by messages? The first problem is known as the characterization problem and has been studied for several types of IRS. In this thesis, we study the characterization problem for various schemes in which the labels assigned to the vertices are d-ary integer tuples (d-dimensional IRS) and the label assigned to each link of the network is a list of d 1-dimensional intervals. This is known as Multi-dimensional IRS (MIRS) and is an extension of the the original IRS. We completely characterize the class of network which support MIRS for linear (which has no cyclic intervals) and strict (which has no intervals assigned to a link at a node v containing the label of v) MIRS. In real networks usually the costs of links may vary over time (dynamic cost links). We also give a complete characterization for the class of networks which support a certain type of MIRS which routes all messages on shortest paths in a network with dynamic cost links. The main criterion used to measure the quality of routing (the second problem) is the length of routing paths. In this thesis we also investigate this problem for MIRS and prove two lower bounds on the length of the longest routing path. These are the only known general results for MIRS. Finally, we study the relationship between various types of MIRS and the problem of drawing a hypergraph. Using some of our results we prove a tight bound on the number of dimensions of the space needed to draw a hypergraph.

Research in the area of academic writing has demonstrated that writing varies significantly across disciplines and among genres within disciplines. Two important approaches to studying diversity in disciplinary academic writing have been the genre-based approach and the corpus-based approach. Genre studies have considered the situatedness of writing tasks, including the larger sociocultural context of the discourse community (e.g., Berkenkotter & Huckin, 1995; Bhatia, 2004) as well as the move structure in specific genres like the research article (e.g., Swales, 1990, 2004). Corpus- based studies of disciplinary writing have focused more closely on the linguistic variation across registers, with the re-search article being the most widely studied register (e.g., Cortes, 2004; Gray, 2011). Studies of under-graduate writing in the disciplines have tended to focus on task classification (e.g., Braine, 1989; Horowitz, 1986a), literacy demands (e.g.,Carson, Chase, Gibson, & Hargrove, 1992), or student development (e.g., Carroll, 2002; Leki, 2007). The purpose of the present study is to build on these previous lines of research to explore undergraduate disciplinary writing from multiple perspectives in order to better prepare English language learners for the writing tasks they might encounter in their majors at a US university. Specifically, this exploratory study examines two disciplines: psychology and chemistry. Through writing task classification (following Horowitz, 1986), qualitative interviews with faculty and students in each discipline, and a corpus-based text analysis of course readings and upper-division student writing, the study yielded several important findings. With regard to writing tasks, psychology writing tasks showed more variety than chemistry. In addition, lower division classes had fewer writing assignments than upper division courses, particularly in psychology. The findings also showed a mismatch between the expectations of instructors in each discipline and students’ understanding of such writing expectations. The linguistic analysis of course readings and student writing demonstrated differences in language use both between registers and across disciplines.

Routing messages between pairs of nodes is one of the most fundamental tasks in any distributed computing system. An Interval Routing Scheme (IRS) is a well-known, space-efficient routing strategy for routing messages in a network. In this scheme, each node of the network is assigned an integer label and each link at each node is labeled with an interval. The interval assigned to a link l at a node v indicates the set of destination addresses of the messages which should be forwarded through l at v. When studying interval routing schemes, there are two main problems to be considered: a) Which classes of networks do support a specific routing scheme? b) Assuming that a given network supports IRS, how good are the paths traversed by messages? The first problem is known as the characterization problem and has been studied for several types of IRS. In this thesis, we study the characterization problem for various schemes in which the labels assigned to the vertices are d-ary integer tuples (d-dimensional IRS) and the label assigned to each link of the network is a list of d 1-dimensional intervals. This is known as Multi-dimensional IRS (MIRS) and is an extension of the the original IRS. We completely characterize the class of network which support MIRS for linear (which has no cyclic intervals) and strict (which has no intervals assigned to a link at a node v containing the label of v) MIRS. In real networks usually the costs of links may vary over time (dynamic cost links). We also give a complete characterization for the class of networks which support a certain type of MIRS which routes all messages on shortest paths in a network with dynamic cost links. The main criterion used to measure the quality of routing (the second problem) is the length of routing paths. In this thesis we also investigate this problem for MIRS and prove two lower bounds on the length of the longest routing path. These are the only known general results for MIRS. Finally, we study the relationship between various types of MIRS and the problem of drawing a hypergraph. Using some of our results we prove a tight bound on the number of dimensions of the space needed to draw a hypergraph.

Polymer electrolyte membrane (PEM) fuel cells are promising alternative green power source for mobile, portable and stationary applications. However, their cost, durability, and performance are impacted by their sensitivity to impurities in fuel stream. Carbon monoxide (CO), an impurity commonly present in the hydrogen gas produced from hydrocarbon fuels, is known to have a significant degrading effect on PEM fuel cell performance because CO has a strong affinity to the platinum-based catalyst. At present, most studies in literature are limited to either experimental or simplified-dimensional analysis/modeling. In this thesis research, a three-dimensional (3D) multiphase PEM fuel cell model with the CO poisoning and O2 bleeding is developed based on the conservation laws for mass, momentum, energy, and species, and implemented in the commercial software Fluent (6.3.26) through the user-defined functions. Numerical simulations are conducted to simulate a single PEM fuel cell including flow channels, gas diffusion layers, catalyst layers, and PEM. The simulation results are compared with experimental data favorably. The result shows that the reaction rate of hydrogen in the anode catalyst layer is higher near the membrane layer, decreasing towards the gas diffusion layer (GDL) interface, and the reaction rate in general is higher in the inlet region and decreases towards the exit region of the flow channel. It means that the outlet of anode catalyst layer next to the flow channel and GDL has suffered the most significant poisoning effect. The result helps optimize the design of anode catalyst layer by embedding more platinum on the most poisoned area to increase available surface for hydrogen adsorption; similarly, reducing platinum loading on the less poisoned area. The fuel cell performance can be almost fully recovered when switching the anode fuel mixture to pure hydrogen, though it takes a long period of time. The reaction rate of hydrogen decreases significantly along the flow channel when impurity mixture is provided; while there is little change along the channel for pure hydrogen fuel. Adding oxygen into the anode fuel mixture can mitigate CO poisoning, but there is a time delay when the oxygen is introduced into the anode stream and when the performance starts to recover. It is observed that at the beginning of oxygen introduced in the anode stream the recovery rate in the region adjacent to the channel outlet is faster than the rate in the region close to the inlet. This difference in the recovery rate gradually becomes smaller over time. In addition, the influence of CO poisoning and oxygen bleeding on multi-phase water is investigated. The influence on dissolved water is only clearly seen in the anode catalyst layer next to the land area. Finally, response to sudden load changes is simulated by changing cell voltage. It is found that the overshoot and undershoot are more significant at high current densities.

Fundamental to the debate of culture and its impact is the identification of the dimensions that comprise it. The impact of culture as an explanatory variable can be found in various social, scientific, and economic arenas, such as social perception, economic development, and the organization of industries and companies. By identifying and measuring these dimensions, researchers can then organize cultures empirically and develop complex descriptions of various cultures. The study aimed to test the structure of the dimensions proposed by Ho and Chiu (1994) by means of scale development. Test-item writers involved psychology graduate students of various nationalities with the purpose of addressing reliability issues of previous measures by virtue of increased content breadth. The study also aimed to investigate the notion that cultural tendencies vary by dimension across geographical regions. Phase-I factor analysis results indicated that a 5-factor solution (responsibility, affiliation, social welfare, religion, and achievement) should be retained. Phase-II involved administering the scale to an international and American student sample that formed the basis for group comparisons. The results for the group comparisons were illuminating, providing evidence for the conceptualization of individualism and collectivism as worldviews and that the groups varied in their worldview depending on the pertinent dimension being measured. Implications for organizational research are discussed within the framework of linking individualism and collectivism to workplace variables. This study hopes to spur further empirical research in the area to catch up with the progressing theoretical development through expanded cultural dimensions, theory refinement, determining the process(es) by which cultural factors are linked to work behaviors, and uncover the various areas of applicability and research.

Polymer electrolyte membrane (PEM) fuel cells are promising alternative green power source for mobile, portable and stationary applications. However, their cost, durability, and performance are impacted by their sensitivity to impurities in fuel stream. Carbon monoxide (CO), an impurity commonly present in the hydrogen gas produced from hydrocarbon fuels, is known to have a significant degrading effect on PEM fuel cell performance because CO has a strong affinity to the platinum-based catalyst. At present, most studies in literature are limited to either experimental or simplified-dimensional analysis/modeling. In this thesis research, a three-dimensional (3D) multiphase PEM fuel cell model with the CO poisoning and O2 bleeding is developed based on the conservation laws for mass, momentum, energy, and species, and implemented in the commercial software Fluent (6.3.26) through the user-defined functions. Numerical simulations are conducted to simulate a single PEM fuel cell including flow channels, gas diffusion layers, catalyst layers, and PEM. The simulation results are compared with experimental data favorably. The result shows that the reaction rate of hydrogen in the anode catalyst layer is higher near the membrane layer, decreasing towards the gas diffusion layer (GDL) interface, and the reaction rate in general is higher in the inlet region and decreases towards the exit region of the flow channel. It means that the outlet of anode catalyst layer next to the flow channel and GDL has suffered the most significant poisoning effect. The result helps optimize the design of anode catalyst layer by embedding more platinum on the most poisoned area to increase available surface for hydrogen adsorption; similarly, reducing platinum loading on the less poisoned area. The fuel cell performance can be almost fully recovered when switching the anode fuel mixture to pure hydrogen, though it takes a long period of time. The reaction rate of hydrogen decreases significantly along the flow channel when impurity mixture is provided; while there is little change along the channel for pure hydrogen fuel. Adding oxygen into the anode fuel mixture can mitigate CO poisoning, but there is a time delay when the oxygen is introduced into the anode stream and when the performance starts to recover. It is observed that at the beginning of oxygen introduced in the anode stream the recovery rate in the region adjacent to the channel outlet is faster than the rate in the region close to the inlet. This difference in the recovery rate gradually becomes smaller over time. In addition, the influence of CO poisoning and oxygen bleeding on multi-phase water is investigated. The influence on dissolved water is only clearly seen in the anode catalyst layer next to the land area. Finally, response to sudden load changes is simulated by changing cell voltage. It is found that the overshoot and undershoot are more significant at high current densities.

Research in multi-touch interaction has typically been focused on direct spatial manipulation; techniques have been created to result in the most intuitive mapping between the movement of the hand and the resultant change in the virtual object. As we attempt to design for more complex operations, the effectiveness of spatial manipulation as a metaphor becomes weak. We introduce two new platforms for multi-touch computing: a gesture recognition system, and a new interaction technique. I present Multi-Tap Sliders, a new interaction technique for operation in what we call non-spatial parametric spaces. Such spaces do not have an obvious literal spatial representation, (Eg.: exposure, brightness, contrast and saturation for image editing). The multi-tap sliders encourage the user to keep her visual focus on the tar- get, instead of requiring her to look back at the interface. My research emphasizes ergonomics, clear visual design, and fluid transition between modes of operation. Through a series of iterations, I develop a new technique for quickly selecting and adjusting multiple numerical parameters. Evaluations of multi-tap sliders show improvements over traditional sliders. To facilitate further research on multi-touch gestural interaction, I developed mGestr: a training and recognition system using hidden Markov models for designing a multi-touch gesture set. Our evaluation shows successful recognition rates of up to 95%. The recognition framework is packaged into a service for easy integration with existing applications.

This dissertation uncovers and examines linguistic and functional patterns of student writing in the first two years of college. A corpus of student papers from six disciplines (philosophy, English, psychology, biology, chemistry, and physics) was collected, and multi-dimensional (MD) analysis (Biber, 1988) was used to examine the ways that discipline and paper type influence writing. Further explorations of the data compare lower-level student writing to upper-level student writing, professional academic biology writing, and the discipline-specific approximations of an English for Specific Purposes (ESP) course. Findings show that specificity of both linguistic and functional properties exist even at such low levels of disciplinary acculturation. These studies are followed by a summary and contextualization of their findings. Finally, future inquiry using collected data and future investigations into student literacy practices are proposed.

A Mobile Ad hoc Network (MANET) is typically a set of wireless mobile nodes enabled to communicate dynamically in a multi-hop manner without any pre-existing network infrastructure. MANETs have several unique characteristics in contrast to other typical networks, such as dynamic topology, intermittent connectivity, limited resources, and lack of physical security. Securing MANETs is a critical issue as these are vulnerable to many different attacks and failures and have no clear line of defence. To develop effective security services in MANETs, it is important to consider an appropriate trust infrastructure which is tailored to a given MANET and associated application. However, most of the proposed trust infrastructures do not to take the MANET application context into account. This may result in overly secure MANETs that incur an increase in performance and communication overheads due to possible unnecessary security measures. Designing and evaluating trust infrastructures for MANETs is very challenging. This stems from several pivotal overlapping aspects such as MANET constraints, application settings and performance. Also, there is a lack of practical approaches for assessing security in MANETs that take into account most of these aspects. Based on this, this thesis provides a methodological approach which consists of well-structured stages that allows the exploration of possible security alternatives and evaluates these alternatives against dimensions to selecting the best option. These dimensions include the operational level, security strength, performance, MANET contexts along with main security components in a form of a multidimensional security conceptual framework. The methodology describes interdependencies among these dimensions, focusing specifically on the service operational level in the network. To explore these different possibilities, the Server-based Security Architectures for MANETs (SSAM) simulation model has been created in the OMNeT++ simulation language. The thesis describes the conceptualisation, implementation, verification and validation of SSAM, as well as experimentation approaches that use SSAM to support the methodology of this thesis. In addition, three different real cases scenarios (academic, emergency and military domains) are incorporated in this study to substantiate the feasibility of the proposed methodology. The outcome of this approach provides MANET developers with a strategy along with guidelines of how to consider the appropriate security infrastructure that satisfies the settings and requirements of given MANET context.

This thesis presents a flexible graphene/polyvinylidene difluoride (PVDF)/graphene sandwich for three-dimensional touch interactivity. Here, an x-y plane touch is sensed using graphene capacitive elements, while force sensing in the z-direction is by a piezoelectric PVDF/graphene sandwich. By employing different frequency bands for the capacitive- and force-induced electrical signals, the two stimuli are detected simultaneously, achieving three-dimensional touch sensing. Static force sensing and elimination of propagated stress are achieved by augmenting the transient piezo output with the capacitive touch, thus overcoming the intrinsic inability of the piezoelectric material in detecting non-transient force signals and avoiding force touch mis-registration by propagated stress. As a capacitive signal is important for force touch interpretation, optimization algorithms have been developed and implemented. With correlated double sampling (CDS) and spatial low-pass filtering (SLPF) based techniques, the signal-to-noise ratio (SNR) of the capacitive touch signal is boosted by 15.6 dB, indicating improved detection accuracy. In terms of the readout speed, fixed pattern and random pattern related down-sampling techniques are applied, giving rise to reductions in both readout time (11.3 ms) and power consumption (8.79 mW).