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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
451

Sukamų daugiasluoksnių konstrukcinių elementų projektavimo proceso modeliavimas / The Modeling of Design of Multi-layer Construction Elements Subjected by Turning

Zacharovienė, Elvyra 10 September 2004 (has links)
Program „The modeling of design of multi-layer construction elements subjected by turning“ is created for students of mechanical engineering course and designers. Using this program it is possible to calculate inertia momentum of pole area, stiffness for shear, shear stresses, and maximum meanings of shear stress and twisting angle. The input parameters are shear modulus of materials, inner diameter of pivot, thickness and material of each layer, torsion moment and length of pivot. The output is initial data and results of calculation. In addition the diagram of distribution of stresses is drawn.
452

Scalable Routing for Networks of Dynamic Substrates

Drazic, Boris 18 March 2014 (has links)
The ever-increasing number of devices capable of, not only connecting to existing communication networks, but also, independently creating new ones is defining a new communication network, in which the Internet is only one of the substrate networks pro- viding connectivity between diverse devices. This is a network with many interconnected mobile devices connecting to infrastructure networks and creating their own dynamic substrate networks. We present a novel routing scheme for diverse collections of substrate networks with a mix of mobile and static nodes. A key element of the routing scheme is to utilize the exiting routing paths in substrate networks, and set up routing paths between substrate networks. We use sets of nodes as landmarks and define locators that describe node position in the network relative to landmarks. This allows our routing scheme to scale to a large number of nodes, as only information about landmarks needs to be propagated throughout the network.
453

Scalable Routing for Networks of Dynamic Substrates

Drazic, Boris 18 March 2014 (has links)
The ever-increasing number of devices capable of, not only connecting to existing communication networks, but also, independently creating new ones is defining a new communication network, in which the Internet is only one of the substrate networks pro- viding connectivity between diverse devices. This is a network with many interconnected mobile devices connecting to infrastructure networks and creating their own dynamic substrate networks. We present a novel routing scheme for diverse collections of substrate networks with a mix of mobile and static nodes. A key element of the routing scheme is to utilize the exiting routing paths in substrate networks, and set up routing paths between substrate networks. We use sets of nodes as landmarks and define locators that describe node position in the network relative to landmarks. This allows our routing scheme to scale to a large number of nodes, as only information about landmarks needs to be propagated throughout the network.
454

An Exploratory Study of Storytelling Using Digital Tabletops

Mostafapourdehcheshmeh, Mehrnaz 18 September 2013 (has links)
Storytelling is a powerful means of communication that has been employed by humankind from the early stages of development. As technology has advanced, the medium through which people tell stories has evolved from verbal, to writing, performing on stage, and more recently television, movies, and video games. A promising medium for the telling of stories in an in-person, one-on-one or one-to-many setting is a digital table—a large, horizontal multi-touch surface—that can provide quick access to visuals and narrative elements at the touch of one’s hands and fingers. In this work, I present the results of an exploratory study on storytellers’ interaction behaviours while working with digital tables, and its physical counterparts of sand and water. My results highlight some of the differences in these media that can both help and hinder a storyteller’s narrative process. I use these findings to present design implications for the design of applications for storytelling on digital multi-touch surfaces.
455

CONSENSUS ANALYSIS ON NETWORKED MULTI-AGENT SYSTEMS WITH STOCHASTIC COMMUNICATION LINK FAILURE

Gong, Xiang 15 February 2013 (has links)
This thesis is to develop a novel consensus algorithm or protocol for multi-agent systems in the event of communication link failure over the network. The structure or topology of the system is modeled by an algebraic graph theory, and defined as a discrete time-invariant system with a second-order dynamics. The communication link failure is governed by a Bernoulli process. Lyapunov-based methodologies and Linear Matrix Inequality (LMI) techniques are then applied to find an appropriate controller gain by satisfying the sufficient conditions of the error dynamics. Therefore, the controller with the calculated gain is guaranteed to drive the system to reach a consensus. Finally, simulation and experiment studies are carried out by using two Mobile Robot Pioneer 3-DXs and one Pioneer 3-AT as a team to verify the proposed work.
456

A Multi-Robot Coordination Methodology for Wilderness Search and Rescue

Macwan, Ashish 13 January 2014 (has links)
One of the applications where the use of robots can be beneficial is Wilderness Search and Rescue (WiSAR), which involves the search for a possibly mobile but non-trackable lost person (i.e., the target) in wilderness environments. A mobile target implies that the search area grows continuously and potentially without bound. This fact, combined with the presence of typically rugged, varying terrain and the possibility of inclement weather, poses a considerable challenge to human Search and Rescue (SAR) personnel with respect to the time and effort required to perform the search and the danger entailed to the searchers. Mobile robots can be advantageous in WiSAR due to their ability to provide consistent performance without getting tired and their lower susceptibility to harsh weather conditions compared to humans. Thus, a coordinated team of robots that can assist human SAR personnel by autonomously performing searches in WiSAR scenarios would be of great value. However, to date, a suitable multi-robot coordination methodology for autonomous search that can satisfactorily address the issues relevant to WiSAR is lacking. The objective of this Dissertation is, thus, to develop a methodology that can autonomously coordinate the search strategy of a multi-robot team in wilderness environments to locate a moving target that is neither continuously nor intermittently observed during the search process. Three issues in particular are addressed: (i) target-location prediction, (ii) robot deployment, and (iii) robot-path planning. The corresponding solution approaches devised to address these issues incorporate the influence of varying terrain that may contain a priori known and unknown obstacles, and deal with unique target physiology and psychology as well as found clues left behind by the target. The solution methods for these three tasks work seamlessly together resulting in a tractable MRC methodology for autonomous robotic WiSAR. Comprehensive simulations have been performed that validate the overall proposed methodology. Moreover, the tangible benefits provided by this methodology were further revealed through its comparison with an alternative search method.
457

Symbiotic Evolutionary Subspace Clustering (S-ESC)

Vahdat, Ali R. 08 November 2013 (has links)
Subspace clustering identifies the attribute support for each cluster as well as identifying the location and number of clusters. In the most general case, attributes associated with each cluster could be unique. A multi-objective evolutionary method is proposed to identify the unique attribute support of each cluster while detecting its data instances. The proposed algorithm, Symbiotic Evolutionary Subspace Clustering (S-ESC) borrows from symbiosis in the sense that each clustering solution is defined in terms of a host, which is formed by a number of co-evolved cluster centroids (or symbionts). Symbionts define clusters and therefore attribute subspaces, whereas hosts define sets of clusters to constitute a non-degenerate clustering solution. The symbiotic representation of S-ESC is the key to making it scalable to high-dimensional datasets, while a subsampling process makes it scalable to large-scale datasets. Performance of the S-ESC algorithm was found to be robust across a common parameterization utilized throughout.
458

On the Benefits of Network Coding in Multi-party Video Conferencing

Pu, Yiwei 10 December 2013 (has links)
The widespread use of personal multimedia-rich devices and multi-party video conferencing have made face-to-face communication among multiple users a promising feature. This thesis presents a multi-party conferencing solution with network coding naturally embedded. Our fundamental goal is to study if network coding brings benefits to multi-party conferencing. In this thesis, we first review an existing network coded solution for multi-party conferencing. Then, this solution is evaluated in our framework of evaluating a new transmission protocol for multi-party conferencing. Also, an investigation is set up to dive into the bottlenecks of this network coded solution. Next, an improved solution targeting conferencing services is proposed by tackling the bottlenecks of the existing solution. Based on our experiment results, it is found that network coding does bring benefits in the context of multi-party conferencing.
459

Head Roll Influences on Multi-Sensory Integration for Perception and Action

BURNS, Jessica Katherine 21 July 2011 (has links)
The representation of ourselves and our environment is based on the combination of information from multiple sensory systems. Each sensory modality is represented within a different frame of reference, in other words each sensory system uses a different code to represent the same properties of the environment (ex. visual stimuli in an eye-centered frame of reference; hand position would be shoulder-centered). Combing this information into a singular coordinate frame is complex. For instance, the eye and shoulder have different centers of rotation, therefore any changes in eye position or body posture will affect the relationship between them. What is still unknown is how the brain integrates these different sources of information into an internal representation, and what effect extra-retinal signals can have on this process. This thesis was designed to investigate the effect of head roll on action and perception. In Experiment 1, we wanted to determine how the integration of vision and proprioception for action was affected by changes in head roll. To investigate this question subjects performed a reaching task at three different head roll positions, where they would experience conflicts between their viewed and actual hand position. In Experiment 2, we examined the influence of head roll on sensory perception. To explore this idea subjects performed a task where they needed to judge the position of their unseen index fingertip relative to a visual target. Our findings reveal that eccentric head roll conditions influence both action and perception – revealed by an increase in movement variability and a decreased ability to discriminate the position of the unseen fingertip relative to visual targets. In summary, we have discovered that introducing eccentric head roll positions affects the perception of ourselves within the environment and the way that we integrate sensory information. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2010-09-21 14:07:09.217
460

The Monetary Transmission Mechanism and Business Cycles: The Role of Multi-stage Production with Inventories

Dai, Tiantian 17 September 2012 (has links)
This thesis studies the role of multi-stage production for the monetary transmission mechanism. I employ a monetary search model to show how multi-stage production influences both the long run and the short run effects of money growth. Multi-stage production provides an additional channel for money growth having effects through intermediate goods between different production stages. Extending Shi's (1998) model from a single-stage to a multi-stage production model, I show that money growth rate has an unconventional long run effect on quantities per match, and the long run response of input inventory investment is different from that of output inventory investment. Contrary to classic search models, the steady state effect of money growth on the quantity of finished goods per match is not monotonic and depends on the money growth rate. Furthermore, in steady state the quantities per match first increase with the growth rate of money, before falling for large growth rates. Input inventories arise due to search frictions. Money growth also has hump-shaped real effects on steady state input inventory investment. The intermediate goods build a bridge between the labor market and the finished goods market. Intuitively, households hire more labor with higher future revenue and produce more intermediate goods in order to match the employment level. With more labor and more intermediate goods, finished goods producers can produce more when matched. As a consequence, they are stuck with more input inventories. Moreover, my model suggests that changes in the money growth rate would be one of the reasons for the decline of the inventory-to-sales ratio since the mid-1980s. Finally, I calibrate my model to quarterly US data. Contrary to other work, my model is able to replicate the stylized facts on inventory movements over the business cycle by solely relying on monetary shocks. The theoretical impulse response functions can quantitatively reproduce the corresponding empirical ones estimated in a structure autoregressive model. Moreover, the quantitative analysis supports the argument that input inventories amplify aggregate fluctuations over business cycles. / Thesis (Ph.D, Economics) -- Queen's University, 2012-09-16 20:44:21.876

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