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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.
11

Application of Shallow Water Models on the Inundation Range and Bridge Scouring due to Tsunami

Chen, Yu-Tzung 21 June 2012 (has links)
This research adopted CMCOT model (Cornell Multi-grid Coupled Tsunami Model) to simulate the wave ran up as the tsunami entered the shoaling water of coastlines, the inundation range on land, and the bridge scour caused by tsunami as it made its way upstream in the rivers. The inundation range was estimated with the fault parameters of Manila Trench and a simulation of bell-sphaped curve waves. The result indicated that if the height of bell-sphaped curve was the same as the maximum water level of the tsunami passed to Kaohsiung offshore, the inundation rage was generally consistent. In the simulation of different water level, we discovered that one meter of wave height was sufficient to inundate the entire coastland of Qijin and Gushan District and that the inundation rage would expand as the wave height increased. With the maximum simulated wave height of six meters, the inundation rage included Gushan, Qijin, Yancheng, Qianjin (small scope), Qianzhen, Fengshan, and Xiaogang District. As to the comparison of historical tsunami, according to the particle size analysis of geological survey from the Kaohsiung Mass Rapid Transit, a layer of fine sediment could be found at specific depth, and its particle size (about 8£r) was significantly different than that of other layers. If this fine sediment was the border of tsunami sediment, the height of historical tsunami wave could be 4.9 meters. With regard to bridge scour, Gwando Bridge was chosen as research area. The result from the sediment simulation of COMCOT model was similar to the scour hole and sediment deposition formed by horseshoe vortex system. Based on the result, the scouring and depositing processes were mainly influenced by the particle size of the sediment. In the simulation, the results of different sediment particle sizes were as follows: (1) If the particle size of sediment was greater than 62£gm, the maximum scour depth was less than 4 cm, and the maximum height of deposition was under 3 cm. (2) If the particle size of sediment was between 4 and 62£gm, the maximum scour depth was between 4 and 5 cm, and the maximum height of deposition was between 3 and 4 cm. (3) If the particle size of sediment was smaller than 4£gm, the maximum scour depth was above 6.8 cm, and the maximum height of deposition was greater than 5 cm.
12

Clarification of wool scouring liquors containing sulfated higher alcohols

Sitomer, Louis J. January 1941 (has links)
Master of Science
13

Wool Scouring Tests in Utah

Esplin, Alma C. 01 May 1941 (has links)
Wool as it is shorn from the sheep, is known as grease wool. The first tep in the manufacturing of wool is scouring, or removal of all grease and foreign matter. Within any given grade, as determined by length of staple and fineness of fiber, the yield of clean wool is the primary factor in determining the value of the original grease wool. The price of scoured or clean wool is multiplied by the percentage yield of clean wool to determine the value of the grease wool. Wool is graded and sorted before being scoured by the manufacturer. Large quantities are prepared for the scouring vate and the identity of the grower's clip is lost. Hence, the grower is entirely dependent upon the buyer's estimate of shrinkage or yield of clean wool, unless he obtains a representative sample of his clip and has it scoured to determine the yield. The object of the work reported in this thesis was to obtain information on the variability in yields of clean wool in Utah herds, and to add to work already done on methods of sampling and dtermining yields. Three methods have been used: (1) Whole fleece samples, (2) composite samples, and (3) side samples from individual sheep. Literature concerning each of these methods and other pertinent material is reviewed, and results obtained in Utah are presented.
14

The Engineering Behavior of Artificial Reefs off Southwestern Coast of Taiwan

Lai, Ming-Hsun 18 July 2000 (has links)
The purpose of this study is to incorporate the knowledge and technique of marine geotechnical engineering, underwater acoustic surveying and hydraulic experiment into studying the problems of artificial reefs off Ling-yang, Kaohsiung Country, South-western part of Taiwan deployed in March 1996. Based on hydraulic experiment, we try to observe the scouring mechanism of artificial reefs. Beside, two other reefs Yung-an, Fang-lio reef were surveyed in this study .The ultimate goal of this investigate was intended to deduce ways to solve the problem of excessive scouring and subsidence, and decide the appropriate environment of the seafloor to deploy artificial reefs for promoting fishing developing. The topography of Ling-yang is generally gentle. Based on the test of physics and mechanics, most surficial sediments at the surface was cohesiveless sand sediments including a lot of seashell. Therefore, we deduced that the surficial sediments are easier to drift caused by monsoon and typhoon in summer. The phenomenon indicated that the surface of sediments is unstable when the sediments are cohesiveless or were loaded by other forces. This study showed that there were obvious scouring effect occurred in and around the reefs, Ling-yang, Yung-an and Fang-lio. The most serious scouring area was occurred in Ling-yang, and a majority of reefs have been buried there. Therefore, the major factors, which could induce excessive subsidence or undermining of the artificial reefs in the testing site, were proposed to be scouring effects. Compared with other reef areas, the scouring effect was related to the grain distribution on the seafloor and the velocity of currents. In the aspect of preventing subsidence of reefs, the reefs closely deployed were better than that loosely deployed.
15

A Feasibility Study On Bridge Scour Countermeasures

Ozdemir, Emre Celalettin 01 January 2003 (has links) (PDF)
Many bridges are destroyed or completely failed during floods due to excessive scouring around bridge piers and abutments. Safe bridge design is based on joint consideration of structural, hydraulic, and geotechnical aspects. This study is concerned with the investigation of various types of countermeasures against scouring at bridge sites. The design criteria for various countermeasures are reviewed in terms of hydraulic, hydrologic, constructional, and economical requirements. (Conditions of applicability of these countermeasures are evaluated and designed for different return periods of flow, and hydroeconomic analyses are performed for Esenbosa Bridge). Based on the evaluation of the results of hydroeconomic analyses, combinations of rock riprap and grout filled bags are found to be appropriate measures for piers and abutments against scouring whereas vegetation is observed to be applicable for bank protection.
16

Scouring the Thin City: an investigation into Perth through the medium of mapping

George, Beth, b.george@curtin.edu.au January 2009 (has links)
Perth, Western Australia - a city become region one hundred kilometres in length and expanding yet - is a place variously adored and scorned; one noted widely for its landscape and its horizon, and relatively rarely for its architecture. Young, low lying, and sparsely lined with built form, Perth might be described as a thin city. The intent of this research is to entreat an optimistic and inquisitive reading of the city of Perth through the conceptualisation of a set of six narrative threads. Six fictive interpretations of Perth, each denoting qualities of thinness, are cast toward the factual city, inviting both confirmation and opposition to their themes. They are: private city, wide city, even city, city of the immediate future, reserve city and city of form fixation. The process of elucidating and questioning the presence of these narratives allows for thicknesses to emerge from the city region; latencies with which the city can be redressed. The mechanism for directing this interpretive view of the city is the process of mapping. Each narrative thread has been explored through the formulation of a set of maps as a visual text. Through the paired workings of the narratives and the mappings, opportune conditions and operations are uncovered within the thin city, complexities that belie the ubiquity of its surface. Mappings shift in scope from the scale of the region to a site of richness at its core, sampling out entities, structures and performative processes at work in the city's plan, distilling opportune sites that are then explored via the architectural project. At once analytical and synthetic, mappings identify existing points of intrigue and simultaneously invite their extrapolation. With the thin city narratives driving the content of the maps and forming the basis for their projectual exploration, this research seeks to engage with the nascent city and offer to it an armature for its amplification that operates within the city's delirium, its peculiarity, its distinctiveness.
17

Reduction of scour around circular piers using collars

Pandey, M., Pu, Jaan H., Pourshahbaz, H., Khan, M.A. 08 May 2022 (has links)
Yes / River dynamics and sediment transport play an important role in river bed morphology. Building a bridge pier along the river alters the cross-section of the river and causes the change in flow processes. These changes are mainly responsible for pier scour. In this paper, the usage of collars to reduce scour around circular piers has been investigated. The collars with different diameters and depth positions have been studied using previous data and additional data collected in the present study to assess their effectiveness in reducing scour. Using a wide range of measured data, an empirical equation to compute the maximum scour depth around the circular piers in the presence of collars has been proposed. The proposed equation has been validated and proven to be applicable to a wide range of pier layouts. It has been found that the maximum efficiency can be achieved by fixing the collar at bed level and adopting a collar diameter 1.5–2.5 times of pier diameter.
18

System hydrodynamics to reduce fouling of air-sparged immersed flat-sheet microfiltration membranes

Hamann, Martin Louis 12 1900 (has links)
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Immersed membrane systems hold many operational and environmental advantages in biological treatment of wastewater. However, immersed membrane filtration have only found application in niche markets to date because of higher capital and operating costs associated with membrane fouling. But with capital costs on the decline as membranes become less expensive, immersed membrane systems are increasingly considered as an attractive alternative to conventional treatment processes. Operating costs remain high however, since energy intensive techniques such as air-sparging are required to limit membrane fouling. Improving the air-scouring efficiency of air-sparged immersed membranes can significantly reduce operating costs and unlock the immersed membrane system technology to wider application. The aim of this study was to identify factors that will improve air-scouring efficiency in order to produce guidelines that will help in the development of an immersed microfiltration membrane system with a resulting lower operating cost. Although, the research was done on a flat-sheet microfiltration membrane, the guidelines obtained can be used for the development of any immersed microfiltration membrane arrangement. An airlift reactor set-up was chosen for this study. Six system hydrodynamic factors were evaluated in a factorial design to determine their effects on the cross-flow velocity profile. They were the downcomer area to riser area ratio, top clearance distance, bottom clearance distance, aeration intensity, water depth and air sparger location. It was found that the air-scouring efficiency was increased by generating a cross-flow velocity profile with increased magnitude and uniformity, but absolute uniformity of the cross-flow velocity profile was found to be a prerequisite for optimisation of air-scouring efficiency. Downcomer area to riser area ratio was found to be 99.9% significant in determining the magnitude of the cross-flow velocity profile. Two models were developed to respectively predict the relative magnitude and uniformity of the cross-flow velocity profile. By using these two models, a methodology was developed to design an airlift reactor set-up that would produce system hydrodynamics with an improved air-scouring efficiency. / AFRIKAANSE OPSOMMING: Gesonke membraanstelsels beskik oor talle bedryfs- en omgewingsvoordele in biologiese behandeling van afvalwater. Maar weens die hoër kapitaal- en bedryfskostes wat gepaardgaan met membraanbevuiling, kon gesonke membraanstelsels tot op hede nog net toepassing in nismarkte vind. Maar soos kapitaalkoste daal met al hoe goedkoper membrane beskikbaar, word gesonke membraanstelsels al hoe aanlokliker as ‘n alternatief vir konvensionele behandelingsprosesse. Bedryfskostes bly egter hoog aangesien energie-intensiewe tegnieke soos lugborreling benodig word om membraanbevuiling te vertraag. Deur die effektiwiteit van die skropaksie wat lugborreling aan gesonke membrane bied te verbeter, kan ‘n beduidende besparing in bedryfskostes teweeggebring word om sodoende die uitgebreide toepassing van gesonke membraanstelsel tegnologie moontlik te maak. Hierdie studie het ten doel gehad die identifisering van faktore wat lugskropaksie effektiwiteit kan verbeter en om riglyne op te stel vir die ontwikkeling van ‘n gesonke mikrofiltrasie membraanstelsel met gevolglik laer bedryfskostes. Alhoewel hierdie navorsing ‘n plat-blad mikrofiltrasie membraan gebruik het, kan die riglyne steeds vir enige gesonke mikrofiltrasie membraanuitleg gebruik word. Daar is besluit op ‘n lugligter-reaktor opstelling vir hierdie studie. Ses stelselhidrodinamika faktore is geëvalueer in ‘n faktoriale ontwerp om hul effekte op die kruisvloei snelheidsprofiel te bepaal. Hulle was die afvloei-area tot opvloei-area verhouding, topruimte-afstand, bodemruimte-afstand, belugtingsintensiteit, waterdiepte en belugterligging. Daar is bevind dat die lugskropaksie effektiwiteit verhoog word wanneer ‘n kruisvloei snelheidsprofiel geskep word met ‘n verhoogde grootte en gelykvormigheid, maar die absolute gelykvormigheid van die kruisvloei snelheidsprofiel is gevind om ‘n voorvereiste te wees vir optimale effektiwiteit. Afvloei-area tot opvloei-area verhouding is gevind om 99.9% beduidend te wees in die bepaling van die snelheidsprofiel se grootte. Twee modelle is ontwikkel om afsonderlik die relatiewe grootte en gelykvormigheid van die kruisvloei snelheidsprofiel te voorspel. Die modelle is in ‘n metodologie vervat vir die ontwerp van ‘n lugligter opstelling met stelselhidrodinamika wat verbeterde lugskropaksie effektiwiteit sal skep.
19

Computational two-phase flow and fluid-structure interaction with application to seabed scour

Fadaifard, Hossein 24 October 2014 (has links)
A general framework is described for the solution of two-phase fluid-object interaction problems on the basis of coupling a distributed-Lagrange-multiplier fictitious domain method and a level-set method, intended for application to the problem of seabed scour by ice ridges. The resulting equations are discretized in space using stabilized finite-element methods and integrated in time using the generalized-α method. This approach is simple to implement and applicable to both structured and unstructured meshes in two and three dimensions. By means of examples, it is shown that despite the simplicity of the approach, good results are obtained in comparison with other more computationally demanding methods. A robust approach is utilized for constructing signed-distance functions on arbitrary meshes by introducing artificial numerical diffusivity to improve the robustness of classical signed-distance construction approaches without resorting to common pseudo-time relaxation. Under this approach, signed-distance functions can be rapidly constructed while preserving the numerical convergence properties and, generally, having minimal interfacial perturbation. The method is then applied with a modified deformation procedure for fast and efficient mesh adaptivity, including a discussion how it may be used in computational fluid dynamics. The two-phase fluid-object interaction approach is then customized for modeling of the seabed scour and soil-pipe interaction. In this approach, complex history-dependent soil constitutive models are replaced with a simple strain-rate dependent model. Utilization of this constitutive model along with the framework developed earlier leads to the treatment of seabed scour as a two-phase fluid-object interaction, and the soil-pipe interaction as a fluid-structure interaction problem without the need for remeshing. Good agreement with past experimental and numerical studies are obtained using our approach. The dissertation is concluded by conducting a parametric study of seabed scour in two- and three-dimensions. / text
20

Wool-scouring wastewater treatment at Liu-Tu Industrial District in Taiwan, R. O. C.

Hsiao, Chiang-Pi January 2010 (has links)
Digitized by Kansas Correctional Industries

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