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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

Application and Analysis of Make-up Air Designs in Large Area Smoke Management Systems

Chio, Chia-Shien 27 June 2008 (has links)
Many large space buildings have been built in Taiwan during the past decade and people are very concerned about the fire safety inside the large space. Therefore, a performance-based smoke management system with makeup air system has been exercised. For steady flow, the mass flow of air or smoke exhaust from the top of an atrium equals the mass flow of air entering below the smoke layer. This airflow entering the atrium is referred to as makeup air, and the makeup air can be either supplied naturally or by fan power. In this research, various full-scale hot smoke tests for makeup air systems will be performed to evaluate the temperature distribution of smoke layer and the smoke descending rate at ABRI large space fire lab in Tainan. The experimental results obtained will be utilized as an important reference to establish the code of smoke management system with makeup air system in Taiwan.
32

FUNCTIONALIZED MEMBRANES FOR ENVIRONMENTAL REMEDIATION AND SELECTIVE SEPARATION

Xiao, Li 01 January 2014 (has links)
Membrane process including microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) have provided numerous successful applications ranging from drinking water purification, wastewater treatment, to material recovery. The addition of functional moiety in the membranes pores allows such membranes to be used in challenging areas including tunable separations, toxic metal capture, and catalysis. In this work, polyvinylidene fluoride (PVDF) MF membrane was functionalized with temperature responsive (poly(N-isopropylacrylamide), PNIPAAm) and pH responsive (polyacrylic acid, PAA) polymers. It’s revealed that the permeation of various molecules (water, salt and dextran) through the membrane can be thermally or pH controlled. The introduction of PAA as a polyelectrolyte offers an excellent platform for the immobilization of metal nanoparticles (NPs) applied for degradation of toxic chlorinated organics with significantly increased longevity and stability. The advantage of using temperature and pH responsive polymers/hydrogels also includes the high reactivity and effectiveness in dechlorination. Further advancement on the PVDF functionalization involved the alkaline treatment to create partially defluorinated membrane (Def-PVDF) with conjugated double bounds allowing for the covalent attachment of different polymers. The PAA-Def-PVDF membrane shows pH responsive behavior on both the hydraulic permeability and solute retention. The sponge-like PVDF (SPVDF) membranes by phase inversion were developed through casting PVDF solution on polyester backing. The SPVDF membrane was demonstrated to have 4 times more surface area than commercial PVDF MF membrane, allowing for enhanced nanoparticles loading for chloro-organics degradation. The advanced functionalization method and process were also validated to be able to be scaled-up through the evaluation of full-scale functionalized membrane provided by Ultura Inc. California, USA. Nanofiltration (NF) between UF and RO presents selectivity controlled by both steric and electrostatic repulsions, which are widely used to reject charged species, particularly multivalent ions. In this work, selective permeation of CaCl2 and high sucrose retention are obtained through the modification of nanofiltration membranes with lower charge compared to commercial nanofiltration membrane. The membrane module also shows high stability with constant water permeability in a long-term (two months) test. Extended Nernst-Planck equation were further used to evaluate the experimental results and it fits well.
33

Magnifying the Rural : Moving through the past, present and future of a social space in Västergötland

Andreasson, Jenny January 2013 (has links)
In this project I have worked with strategies at regional level, as well as with alterations to an existing building, to strengthen and celebrate rural systems in a place called Naum, in Vara municipality in Västergötland. This I've donein order to challenge the dichotomy of urban and rural. I find that urbanity is very often celebrated in the architectural discipline, and in the public debate in general. There is a strong hierarchy of spaces in the national discourse of Sweden. By focusing on a rural space that I perceive have low status and connect it to networks that reach out to other spaces, cities, and regions, I treat the urban and rural as a continuous variation rather than a fixed binary. The binary is also challenged already by people constantly moving across this scale. Most of the residents of Naum, mapped out herecommute to Vara Town, or other adjacent towns or cities to work, to go school, to go the doctor, take part in cultural events etc. This project focus on the power of rural networks, on movement, and on rural systems of cooperation, and then I am making a number of alterations at a zoomed-in scale, to offer the inhabitants a more intimate relationship to this agricultural landscape. My project operate both at the intimate scale of an existing bygdegård, which is a specifically rural community space, in Naum, as well as on the larger scale of Vara municipality.To the bygdegård I propose three small scale alterations, a sauna called the 'Storytelling Sauna' (SECTION S S) an overnight stay shelter called the 'Please Stay',and an imaginative element of a 'Wisching-Well-Ditch”. In the larger scale I propose a strategic alteration to the treatment of roadsides, to increase biodiversity and human movement. I call this alteration the 'Thriving Passages'. The project also consist of this room-installation that we are all inside of, that aim to represent the different scales and allow us to move across them, and it consists of mappings of bygdegårds in Vara municipality and in Sweden and how they are connected by human movement, as well as mappings of historical and agricultural layers of this landscape.
34

Creep deformation of rockfill : Back analysis of a full scale test

Gustafsson, Veronica January 2015 (has links)
With the purpose of studying the mechanical properties of uncompacted rockfill and the creep deformation behaviour of rockfill under a load as well as finding a suitable method for estimation of creep deformation behaviour, a full scale embankment loading experiment was performed. The results of this experiment were then evaluated. During the course of this study it became evident to the author that the deformations which were seen in the collected data from the experiment could be classified as creep deformations due to the linear decrease of the deformation against the logarithm of time and the study therefore came to focus on creep. One constitutive equation and one model for estimation of creep deformations were studied, and parameters were obtained through back analysis of experiment data as well as calculation of soil stresses. The creep model was based on a logarithmic approximation of the creep deformations and the creep equation was based on a power function. The creep model could also be simplified and evaluated as an equation and when a comparison was made between the equations and the measured results this showed that the logarithmic equation resulted in estimates closer to the measured deformations than what the power function did, therefore a logarithmic function is a better approximation to the deformations of the rockfill at Norvik than the power function. When the creep model was evaluated as intended, based on the soil stresses, the resulting creep estimates were less accurate, they was however still within the limits of what can be considered as admissible. The conclusion is that a logarithmic function describes the creep deformation of the rockfill at Norvik better than a power function and that the creep model by Kristensen is suitable for estimating the creep deformations. This since the creep model also provides a way of estimating deformations occurring under stress conditions other than the ones for which the creep test was performed.
35

Performance of Transverse Post-Tensioned Joints Subjected to Negative Bending and Shear Stresses on Full Scale, Full Depth, Precast Concrete Bridge Deck System

Roberts, Kayde Steven 01 May 2011 (has links)
Accelerated bridge construction has quickly become the preferred method for the Utah Department of Transportation (UDOT) as well as many other DOT’s across the United States. This type of construction requires the use of full depth precast panels for the construction of the bridge deck. The segmented deck panels produce transverse joints between panels and have come to be known as the weakest portion of the deck. Cracking often occurs at these joints and is reflected through the deck overlay where water accesses and begins corrosion of the reinforcement and superstructure below. For this reason post-tensioning of the deck panels is becoming a regular practice to ensure that the deck behaves more monolithically, limiting cracking. The current post-tensioning used by UDOT inhibits future replacement of single deck panels and requires that all panels be replaced once one panel is deemed defective. The new curved bolt connection provides the necessary compressive stresses across the transverse joints but makes future replacement of a single deck panel possible without replacing the entire bridge deck. To better understand the behavior of the new curved bolt connection under loadings, laboratory testing was undertaken on both the curved bolt and the current post-tensioning used by UDOT. The testing specimens included full-scale, full-depth, precast panels that were connected using both system. The testing induced typical stresses on the panels and connections, subjecting them to negative bending and shear. The overall performance of the curved bolt proved satisfactory. The moment capacity of both connections surpassed all theoretical calculations. The yield and plastic moments were 17% and 16% lower, respectively, than the UDOT post-tension system while at those moments deflection was relatively the same. Due to the anchorage location of the curved bolts, the reinforcement around the transverse joint received up to 5 times the strain of that of the post-tension connections. Although both systems performed well when subjected to shear forces and as compared to the theoretical capacities, the post-tension connection greatly surpassed the curved bolt in shear capacity.
36

The Weave

Seipel, Alice, Carlsson, Hilda January 2022 (has links)
This project starts starts out in wanting to somehow investigate the public space. Beginning in the questions of: What kind of interventions can we achieve in the public space? What is allowed, what is encouraged - what is not? How easy or how difficult is it to achieve building something within the folds of the public space of our city?  On the scale of the intervention itself, we were interested in what things could be investigated through design and materiality: How can we, through this design, encapsulate and measure softer, hard-to-grasp elements such as time, changes and interactions? How can we design a structure that will be responsive to the traces and manifestations of these things? What materials and organization of these can embody them?
37

Evaluating the Effect of Decking Fasteners on the Seismic Behavior of Steel Moment Frame Plastic Hinge Regions

Toellner, Bradley W. 06 June 2013 (has links)
A series of full-scale beam-to-column moment connection tests were completed to determine the effects of powder actuated fasteners (PAF) and puddle welds on the seismic behavior of steel moment connections.  In seismic regions, PAF are currently prohibited in the connection region (referred to as the protected zone) due to the concern of low-cycle fatigue fracture.  There is almost no information available in the literature regarding the seismic behavior of moment connections with PAF or puddle welds. Full-scale connection testing is the most accurate way to investigate the behavior of different moment connections with common defects and fasteners applied in the protected zone.  However, it is cost prohibitive to conduct full-scale testing programs that are sufficiently comprehensive to investigate a wide range of defect types, severity, and locations.  For this reason, it is desired to develop alternative methods of investigation.  A finite element (FE) model capable of simulating both the global deformation patterns and local buckling effects in a moment connection has been developed.  Validated FE models will allow for further evaluation through numerical simulation of additional configurations.  Furthermore, alternate, more economical, test configurations to experimentally investigate the effect of defects on steel moment connections were explored.  This report discusses the full-scale test setup, results and analysis of completed experimental testing, the development of an FE connection model, and the preliminary development of alternate test configurations. / Master of Science
38

Dynamic Testing of a Full-Scale Pile Cap with Dense Silty Sand Backfill

Valentine, Todd J. 18 July 2007 (has links) (PDF)
Full-scale dynamic lateral load tests were performed on a pile cap with a dense silty sand backfill condition. Two hydraulic load actuators connected a test pile cap with a reaction cap. The load actuators incrementally loaded the test cap up to 50 mm of displacement. After each load increment, the displacement was held constant while an eccentric mass shaker induced dynamic loads under a ramping sequence from 1 Hz to 10 Hz. A baseline response was developed under a no backfill condition. Passive soil pressure was measured using pressure cells and tactile sensors. It was concluded that the presence of the backfill significantly increased the lateral load resistance of the pile-cap system, with the resistance nearly doubling at a 50 mm deflection level. After initial loading, the pile cap system experienced a loss in load resistance. In the case with backfill present, this relaxation generally represented a 10 to 15% loss in resistance. Additionally, after undergoing dynamic, cyclic loading, the resistance was approximately 40 to 80% of its initial value. Dynamic displacement amplitudes were on the order of 0 to 2 mm. Passive pressure from the backfill was observed to be non-linear with a concentration of pressure near the bottom of the pile cap. Rankine, Coulomb, and log-spiral earth pressure theories underestimated the passive earth pressure from the backfill by at least 30%. The natural frequency of the pile cap increased with increasing with static displacement level while placement of the backfill further increased the frequency of the pile cap. On average, the presence of the backfill increased the reloading stiffness of the pile cap by a factor of three to four, whereas the damping ratio increased by a factor of two. The dense silty sand backfill acting by itself on the face of the 1.12 m tall and 5.18 m wide pile cap face exhibited a reloading stiffness on the order of 120 to 250 kN/mm and a damping ratio of 30 to 70%. These damping ratios are significantly higher than that typical expected for structural materials but appear to be consistent with values for soils.
39

Experimental response and code modelling of continuous concrete slabs reinforced with BFRP bars

Mahroug, Mohamed E.M., Ashour, Ashraf, Lam, Dennis January 2014 (has links)
This paper presents test results and code predictions of four continuously and two simply supported concrete slabs reinforced with basalt fibre reinforced polymer (BFRP) bars. One continuously supported steel reinforced concrete slab was also tested for comparison purposes. All slabs tested were 500 mm in width and 150 mm in depth. The simply supported slabs had a span of 2000 mm, whereas the continuous slabs had two equal spans, each of 2000 mm. Different combinations of under and over BFRP reinforcement at the top and bottom layers of slabs were investigated. The continuously supported BFRP reinforced concrete slabs exhibited larger deflections and wider cracks than the counterpart reinforced with steel. Furthermore, the over reinforced BFRP reinforced concrete slab at the top and bottom layers showed the highest load capacity and the least deflection of all BFRP slabs tested. All continuous BFRP reinforced concrete slabs failed owing to combined shear and flexure at the middle support region. ISIS-M03-07 and CSA S806-06 design guidelines reasonably predicted the deflection of the BFRP slabs tested. However, ACI 440-1R-06 underestimated the BFRP slab deflections and overestimated the moment capacities at mid-span and over support sections.
40

Simulation of full-scale reverse osmosis filtration system for the removal of N-nitrosodimethylamine from wastewater

Al-Obaidi, Mudhar A.A.R., Kara-Zaitri, Chakib, Mujtaba, Iqbal M. 22 December 2017 (has links)
Yes / Reverse osmosis (RO) is becoming one of the most promising technologies used in wastewater treatment because it offers high rate of contaminant rejection and lower energy consumption in comparison with other thermal treatment processes. Earlier research by the same authors in respect of a distributed one-dimensional mathematical model for a single spiral-wound RO membrane module based on the solution-diffusion model has been used in this paper to simulate the rejection of NDMA (N-nitrosodimethylamine) from wastewater in a series of seven RO elements full-scale treatment plant. Firstly, the applicability of this model has been evaluated using a simulation study and the results have been compared against experimental data gathered from the literature for a given plant. Secondly, further simulation and analysis studies are carried out to assess the performance of the plant for NDMA rejection and recovery rate under different operating conditions of feed pressure, flow rate, and concentration. For the studied RO configuration, it is concluded that a maximum of 55.1% NDMA rejection can be achieved, which confirms the remaining issue of lower NDMA rejection.

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