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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.
31

Development of a portable aerosol collector and spectrometer (PACS)

Cai, Changjie 01 May 2018 (has links)
The overall goal of this doctoral dissertation is to develop a prototype instrument, a Portable Aerosol Collector and Spectrometer (PACS), that can continuously measure aerosol size distributions by number, surface area and mass concentrations over a wide size range (from 10 nm to 10 µm) while also collecting particles with impactor and diffusion stages for post-sampling chemical analyses. To achieve the goal, in the first study, we designed, built and tested the PACS hardware. The PACS consists of a six-stage particle size selector, a valve system, a water condensation particle counter to measure number concentrations and a photometer to measure mass concentrations. The valve system diverts airflow to pass sequentially through upstream stages of the selector to the detectors. The stages of the selector include three impactor and two diffusion stages, which resolve particles by size and collect particles for chemical analysis. Particle penetration by size was measured through each stage to determine actual performance and account for particle losses. The measured d50 of each stage (aerodynamic diameter for impactor stages and geometric diameter for diffusion stages) was similar to the design. The pressure drop of each stage was sufficiently low to permit its operation with portable air pumps. In the second study, we developed a multi-modal log-normal (MMLN) fitting algorithm to leverage the multi-metric, low-resolution data from one sequence of PACS measurements to estimate aerosol size distributions of number, surface area, and mass concentration in near-real-time. The algorithm uses a grid-search process and a constrained linear least-square (CLLS) solver to find a tri-mode (ultrafine, fine, and coarse), log-normal distribution that best fits the input data. We refined the algorithm to obtain accurate and precise size distributions for four aerosols typical of diverse environments: clean background, urban and freeway, coal power plant, and marine surface. Sensitivity studies were conducted to explore the influence of unknown particle density and shape factor on algorithm output. An adaptive process that refined the ranges and step sizes of the grid-search reduced the computation time to fit a single size distribution in near-real-time. Assuming standard density spheres, the aerosol size distributions fit well with the normalized mean bias (NMB) of -4.9% to 3.5%, normalized mean error (NME) of 3.3% to 27.6%, and R2 values of 0.90 to 1.00. The fitted number and mass concentration biases were within ± 10% regardless of uncertainties in density and shape. With this algorithm, the PACS is able to estimate aerosol size distributions by number, surface area, and mass concentrations from 10 nm to 10 µm in near-real-time. In the third study, we developed a new algorithm–the mass distribution by composition and size (MDCS) algorithm–to estimate the mass size distribution of various particle compositions. Then we compared the PACS for measuring multi-mode aerosols to three reference instruments, including a scanning mobility particle sizer (SMPS), an aerodynamic particle sizer (APS) and a nano micro-orifice uniform deposit impactor (nanoMOUDI). We used inductively coupled plasma mass spectrometry to measure the mass of collected particles on PACS and nanoMOUDI stages by element. For the three-mode aerosol, the aerosol size distributions in three metrics measured with the PACS agreed well with those measured with the SMPS/APS: number concentration, bias = 9.4% and R2 = 0.96; surface area, bias = 17.8%, R2 = 0.77; mass, bias = -2.2%, R2 = 0.94. Agreement was considerably poorer for the two-mode aerosol, especially for surface area and mass concentrations. Comparing to the nanoMOUDI, for the three-mode aerosol, the PACS estimated the mass median diameters (MMDs) of the coarse mode well, but overestimated the MMDs for ultrafine and fine modes. The PACS overestimated the mass concentrations of ultrafine and fine mode, but underestimated the coarse mode. This work provides insight into a novel way to simultaneously assess airborne aerosol size, composition, and concentration by number, surface area and mass using cost-effective handheld technologies.
32

Att utvärdera AdApt, ett multimodalt konverserande dialogsystem, med PARADISE / Evaluating AdApt, a multi-modal conversational, dialogue system, using PARADISE

Hjalmarsson, Anna January 2003 (has links)
<p>This master’s thesis presents experiences from an evaluation of AdApt, a multi- modal, conversational dialogue system, using PARADISE, PARAdigm for Dialogue System Evaluation, a general framework for evaluation. The purpose of this master’s thesis was to assess PARADISE as an evaluation tool for such a system. An experimental study with 26 subjects was performed. The subjects were asked to interact with one of three different system versions of AdApt. Data was collected through questionnaires, hand tagging of the dialogues and automatic logging of the interaction. Analysis of the results suggests that further research is needed to develop a general framework for evaluation which is easy to apply and can be used for varying kinds of spoken dialogue systems. The data collected in this study can be used as starting point for further research.</p>
33

Towards Diverse Media Augmented E-Book Reader Platform

Alam, Kazi Masudul 06 June 2012 (has links)
In order to leverage the use of various modalities such as audio-visual-touch in instilling learning behaviour, we present an intuitive approach of annotation based hapto-audio-visual interaction with the traditional digital learning materials such as eBooks. By integrating the traditional home entertainment system and respective media in the user's reading experience combined with haptic interfaces, we examine whether such augmentation of modalities influence the user's reading experience in terms of attention, entertainment and retention. The proposed Haptic E-Book (HE-Book) system leverages the haptic jacket, haptic arm band as well as haptic sofa interfaces to receive haptic emotive signals wirelessly in the form of patterned vibrations of the actuators and expresses the learning material by incorporating audio-video based augmentation in order to pave ways for intimate reading experience in the popular eBook platform. We have designed and developed desktop, mobile/tablet based HE-Book system as well as a semi-automated annotation authoring tool. Our system also supports multimedia based diverse quiz augmentations, which can help in learning tracking. We have conducted quantitative and qualitative tests using the developed prototype systems. We have adopted the indirect objective based performance analysis methodology, which is commonly used for multimedia based learning investigation. The user study shows that, there is a positive tendency of accepting multimodal interactions including haptics with traditional eBook reading experience. Though our limited number of laboratory tests reveal, that haptics can be an influencing media in eBook reading experience, but it requires large scale real life tests to provide a concluding remarks.
34

Developing effective virtual simulations and serious games: the effect of background sound cues on visual quality perception

Rojas Gualdron, David Arnulfo 01 August 2012 (has links)
Virtual simulations and serious games (video game-based technologies applied to teaching and learning) have been incorporated in the teaching and training curricula of a large number of professions including medicine/surgery. Despite their benefits, there are open, fundamental issues regarding simulation quality, multi-modal cue interaction, and the resulting effect on visual quality perception and ultimately on knowledge transfer and retention. Here the results of a series of seven studies that examined the effect of background sound (contextually related and non-related with respect to the visual scene) on the perception of visual quality (defined with respect to texture resolution, polygon count) presented in stereoscopic and non-stereoscopic 3D. Results indicate that the perception of visual quality is dependent on ambient (background) sound. The results of these studies have implications for designers and developers of serious games who typically strive for high quality virtual worlds despite the computational burden associated with doing so. The results of these studies also bring us closer to understanding the role of quality, multi-modal interactions, and their effect on visual quality perception. This thesis is part of a larger effort in developing an understanding of virtual environment rendering quality, multi-modal interactions, user-specific factors and their effect on knowledge transfer and retention. / UOIT
35

Microfluidic Studies of Biological and Chemical Processes

Tumarkin, Ethan 04 March 2013 (has links)
This thesis describes the development of microfluidic (MF) platforms for the study of biological and chemical processes. In particular the thesis is divided into two distinct parts: (i) development of a MF methodology to generate tunable cell-laden microenvironments for detailed studies of cell behavior, and (ii) the design and fabrication of MF reactors for studies of chemical reactions. First, this thesis presented the generation of biopolymer microenvironments for cell studies. In the first project we demonstrated a high-throughput MF system for generating cell-laden agarose microgels with a controllable ratio of two different types of cells. The MF co-encapsulation system was shown to be a robust method for identifying autocrine and/or paracrine dependence of specific cell subpopulations. In the second project we studied the effect of the mechanical properties on the behavior of acute myeloid leukemia (AML2) cancer cells. Cell-laden macroscopic agarose gels were prepared at varying agarose concentrations. A modest range of the elastic modulus of the agarose gels were achieved, ranging from 0.62 kPa to 20.21 kPa at room temperature. We observed a pronounced decrease in cell proliferation in stiffer gels when compared to the gels with lower elastic moduli. The second part of the thesis focuses on the development of MF platforms for studying chemical reactions. In the third project presented in this thesis, we exploited the temperature dependent solubility of CO2 in order to: (i) study the temperature mediated CO2 transfer between the gas and the various liquid phases on short time scales, and (ii) to generate bubbles with a dense layer of colloid particles (armoured bubbles). The fourth project involved the fabrication of a multi-modal MF device with integrated analytical probes. The MF device comprised a pH, temperature, and ATR-FTIR probes for in-situ analysis of chemical reactions in real-time. Furthermore, the MF reactor featured a temperature controlled feedback system capable of maintaining on-chip temperatures at flow rates up to 50 mL/hr.
36

Estimating freight costs over a multi-modal network: an auto industry supply chain example

Moore, Amy Marie 10 April 2013 (has links)
The objective of this research is to implement multi-modal cost calculations on a freight transportation network, in order to estimate the cost of freight shipments from parts suppliers to original equipment manufacturers (OEMs), and from OEMs to final consumers involved in the automobile manufacturing industry supply chain. The research will describe gaps in the current freight cost estimation literature, determine the strengths and weaknesses of current practices, and offer possible improvement strategies. The necessary components for this research include: a multi-modal (highway-rail-water-air) network database, the geocoded locations and activity levels of auto industry parts suppliers and OEMs; freight movement cost functions; information on the modes and vehicle/vessel types used for the shipment of certain commodity types; and distance- based travel costs per-mile for these modes. A product of this line of research will be a method that other industries, in other locations, might also use to determine overall freight transportation costs throughout an entire supply chain. The present research effort provides an example using data gathered on the automobile manufacturing industry centered in Georgia and Alabama. The network-based freight costs derived in this research should also be useful in other applications, including the estimation of origin-to-destination flows, as well as in the estimation of transportation costs used in regional and statewide freight planning models.
37

Rethinking the web structure: focusing on events to create better information and experience management

Pack, Derik Leroi 12 July 2004 (has links)
The objective of the following research is to investigate the problem of information management and conveyed experience on the World Wide Web (WWW) when multi-modal sensors and media are available. After studying related areas of work about the web and heterogeneous media, it became apparent that one of the main challenges of the area is the semantic unification of heterogeneous media. This thesis will introduce an event-based model to semantically unify media. An event is defined as something of significance that takes place at a given time and location. Using this definition and the corresponding model, a system will be designed to illustrate practical use cases for events.
38

Multi-Modal Control: From Motion Description Languages to Optimal Control

Delmotte, Florent 16 November 2006 (has links)
The goal of the proposed research is to provide efficient methods for defining, selecting and encoding multi-modal control programs. To this end, modes are recovered from system observations, i.e. quantized input-output strings are converted into consistent mode sequences within the Motion Description Language (MDL) framework. The design of such modes can help identify and predict the behaviors of complex systems (e.g. biological systems such as insects) and inspire the design and control of robust semi-autonomous systems (e.g. navigating robots). In this work, the efficiency of a method will be defined by the complexity and expressiveness of specific control programs. The insistence on low-complexity programs is originally motivated by communication constraints on the computer control of semi-autonomous systems, but also by our belief that, as complex as they may look, natural systems indeed use short motion schemes with few basic behaviors. The attention is first focused on the design of such short-length, few-distinct-modes mode sequences within the MDL framework. Optimal control problems are then addressed. In particular, given a mode sequence, the question of deciding when the system should switch from one mode to another in order to achieve some reachability requirements is studied. Finally, we propose to investigate how sampling strategies affect complexity and reachability, and how an acceptable trade-off between these conflicting entities can be reached.
39

Generalized Pushover Analysis For Unsymmetrical-plan Buildings

Kaatsiz, Kaan 01 July 2012 (has links) (PDF)
Nonlinear response history analysis is regarded as the most accurate analysis procedure for estimating seismic response. Approximate analysis procedures are also available for the determination of seismic response and they are preferred over nonlinear response history analysis since much less computational effort is required and good response prediction is achieved by employing rather simple concepts. A generalized pushover analysis procedure is developed in this thesis study as an approximate analysis tool for estimating the inelastic seismic response of structures under earthquake ground excitations. The procedure consists of applying generalized force vectors to the structure in an incremental form until a prescribed target interstory drift demand is achieved. Corresponding generalized force vectors are derived according to this target drift parameter and include the contribution of all modes. Unlike many approximate analysis procedures, response of the structure is directly obtained from generalized pushover analysis results without employing a modal combination rule, eliminating the errors cultivating from these methods. Compared to nonlinear response history analysis, generalized pushover analysis is less demanding in computational effort and its implementation is simpler relative to other approximate analysis procedures. It is observed that the proposed analysis procedure yields results accurately in comparison to the other nonlinear pushover analysis methods. Accordingly it can be suggested as a convenient and sound analysis tool.
40

Up in the Air: the Global Economy, Economic Development, and Air Transportation in Tampa Bay, Florida

Elbow, Clinton M. 01 January 2011 (has links)
A globally integrated economy is one of the most prominent features of globalization and how city stakeholders respond to the global economy varies from city to city. Connecting to the global economy is often portrayed to be necessary for the continued economic development of a metropolitan area. Large transportation infrastructures such as airports represent one of the most visible ways of connecting to the global economy. Decisions made by city stakeholders regarding airports in order to reposition their city in the global economy have profound consequences for its residents. This thesis aims to examine the role played by air transportation in the processes of globalization present in Tampa Bay, Florida, and focuses specifically on investigating the following research questions: 1) What vision of Tampa Bay is driving the economic development plans of stakeholders of Tampa International Airport and St. Petersburg/Clearwater International Airport? 2) What understanding of globalization do Tampa Bay economic development and air transportation stakeholders have? 3) How does air transportation fit into the economic development plans of Tampa Bay stakeholders and how will each airport play a part? To answer these questions, this thesis uses a qualitative research approach that relies on open-ended, in-depth interviews and artifact review as the methods of data collection. Interviews were conducted with representatives of transportation facilities, government economic development entities, non-profit economic development organizations, and private business interests. These interviews focused on the themes of visions of a future Tampa Bay, stakeholder understandings of globalization, stakeholder perceptions of space-time, and ultimately how air transportation assets in Tampa Bay may or may not be used in the economic development process as a response to the global economy. The results reveal that Tampa Bay stakeholders largely share in a vision of a future Tampa Bay but are not in as much agreement on how to achieve this vision, particularly regarding air transportation. Governance structure is found to be one of the greatest challenges associated with stakeholders' response to the global economy. The subject of governance structure in this case study is tied to changing perceptions of space-time, brought about by the pressures of a global economy, which in the minds of stakeholders requires one to do more with less in order to compete in the global economy. The findings provide important insights on how Tampa Bay stakeholders use air transportation in the process of economic development as a response to the global economy.

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