Dissertations / Theses on the topic 'Creep – Measurement'
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Thomas, A. V. "Measurement of creep damage in CrMoV steels using ultrasonic test techniques." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639199.
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Low alloy steels are widely used in components which operate at high temperatures and pressures, and thus are susceptible to creep. This process involves microstructural changes and degradation of the material which leads to rupture if not detected. Available methods for assessing these factors are currently limited to destructive tests, or to investigation of selected areas of the component surface. Consequently, reliable methods for the detection of creep damage are indispensable, both to guarantee safe operation during the designed lifetime, and to ensure that components possess the physical properties suitable for their required use. Presently, methods including magnetic particle inspection and replication metallography are available for the detection of surface cracks and creep damage. However, there are significant benefits to identifying damage at an earlier stage. A successful plant life strategy demands techniques capable of identifying the initiation of in-service damage within the bulk of structure. Due to the limited availability of test material which may be obtained and the demand for volumetric material characterisation, acoustic NDE techniques offer an attractive means to obtain this information. However, for the effective application of non-destructive characterisation of creep damage, it is fundamentally important to firstly establish an understanding of how acoustic NDE signatures relate to material properties. The research programme undertaken to meet these requirements involved the application of acoustic NDE techniques to meet this task. A specific test programme was developed so that variations in selected microstructural parameters were characterised in terms of structure and properties. These fully characterised specimens then provided the standards required for assessment of volumetric and surface ultrasonic techniques, in both the time and frequency domains.
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Low, Choon Ann Kenneth. "Measurement of elevated temperature creep strains in cross-weld specimens using the grid method." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368969.
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Kostecki, Todd. "DESIGN METHODS FOR ROCK BOLTS USING IN-SITU MEASUREMENT FROM UNDERGROUND COAL MINES." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/dissertations/1695.
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The research in this dissertation was undertaken because of a need for a more accurate, reliable and relatively simple method for determining the combined loading (i.e., axial, flexure and shear) along rock bolts. This combined load determination and understanding also resulted in a relatively simple and reliable new rock bolt design methodology. The new design method was based on a clearer understanding of the actual loading along a grouted rock bolt. To accomplish these research goals, double shear tests were conducted in the lab with reinforced concrete specimens, and field trials were conducted in room and pillar coal mines, with the aim to measure in-situ rock shear. Strain measurements were obtained using rock bolts instrumented with optical fibers that possessed high spatial resolution (≈ 1.25 – 2.5 mm). Corroboration with a past database of rock bolt measurements in shale aided in the deduction of the final support design method. The scientific contributions from this research include the conceptualization of a ground reaction curve that considers time effects such as rock relaxation, long term weakening effects, and lateral rock movement. A new explanation as to why rock bolts creep in practice (i.e., dislocation creep) is described based upon field measurements, which also indicated that the process of in-situ rock shear involves slow episodic movements. Specifically, there are localized compression (i.e., rock pinch) and tensile zones (i.e., dilatation) prior to the occurrence of plastic relief (i.e., rock slip). Finally, the design method is developed using simple factors (i.e., strain and shape factors) and loading conditions (e.g., installed load, rock slip) that occurred throughout the rock bolt’s design life. This approach results in a methodology that considers effects on reinforcement with time and combined loadings. The method is then extended by producing survival and hazard functions for rock bolts to ultimately reduce risk associated with design.
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Touboul, Mathieu. "Étude du comportement mécanique à chaud de l'acier P91 : vers la compréhension du rôle des mécanismes intra/intergranulaires sur la tenue en fluage. Application aux structures soudées." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00819229.
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Il s'agit dans ce travail de développer une démarche multiéchelles, afin d'identifier puis de modéliser le comportement mécanique d'un matériau à gradient de propriétés (un cordon de soudure) en relation avec les hétérogénéités microstructurales responsables de la déformation et de l'endommagement par fluage des aciers P91, matériaux retenus pour des applications de tenue mécanique à chaud des centrales thermiques à flamme. Cette étude porte sur l'utilisation des techniques de mesure de champs cinématiques par corrélation d'images couplées aux simulations numériques par éléments finis. Les différentes zones d'intérêt sont : le métal de base, l'ICHAZ (intercritical heat affected zone), la FGHAZ (fine grain heat affected zone), la CGHAZ (coarse grain heat affected zone) et le métal fondu. L'identification a porté dans un premier temps sur le comportement en traction et traction-relaxation à l'ambiante et à 625°C. Cette phase a permis d'établir une loi de comportement pour chacune des zones du joint soudé et de prédire la zone de localisation de déformation pour une gamme assez large de vitesse de sollicitation.Une attention particulière a ensuite été portée aux essais de fluage, pour lequel le glissement intergranulaire joue un rôle essentiel dans le comportement du cordon de soudure et notamment dans l'ICHAZ. Afin de mettre en évidence le glissement intergranulaire, une technique de microlithographie a été adoptée. L'effet de ce mécanisme sur le comportement macroscopique et à l'échelle locale a été étudié au moyen de simulations numériques par éléments finis avec introduction de zones cohésives. Pour cela une loi cohésive a été élaborée et validée sur une configuration simplifiée à quatre grains. Ce modèle permet également de rendre compte de la transition fluage dislocation - fluage diffusion en retardant le déclenchement du glissement aux joints de grains quand la vitesse de sollicitation augmente.Cette étude est financée par la Chaire EDF-GDF-SUEZ-GRT gaz - ENSMP -ENPC sur la "durabilité des matériaux et des structures pour l'énergie ".
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Peterson, Keith A. "Measurements and observations of interfacial creep in engineering systems." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FPeterson%5FPhD.pdf.
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Thesis (Ph. D. in Mechanical Engineering)--Naval Postgraduate School, September 2002.Dissertation supervisor: Indranath Dutta. Includes bibliographical references (p. 119-124). Also available online.
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Githinji, David Njuguna. "Characterisation of plastic and creep strains from lattice orientation measurements." Thesis, Open University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607486.
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Electron backscatter diffraction (EBSD) is a powerful technique for measuring crystallographic orientation in polycrystalline materials. This thesis explores the potential of EBSD for characterising localised inelastic strain from lattice orientation measurements. A systematic study under uniaxial isothermal loading conditions was performed to examine the influence of microstructure and deformation conditions on strain-induced lattice orientation changes (misorientation). The study was conducted on both service-aged and un-aged Type 316H stainless steels through a series of monotonic tests in tension, compression and in constant load creep. The study demonstrates that the development of misorientation depends on many factors which need consideration before EBSD can be applied for strain assessment. It is shown that the measured evolution of misorientations is a function of microstructure and grain size. A misorientation-based strain assessment method is proposed which is relatively insensitive to microstructure and grain size. In service-aged steel, the measured evolution of misorientations is shown to be independent of the deformation temperature (between 24°C and 550°C) and deformation mode (tension vs. compression) for strain rates down to about . Empirical correlations between the accumulated plastic strain and different misorientation metrics are developed for true strains up to 0.23. However, at 550°C the evolution of measured misorientations is shown to be strain rate dependent below 1O-6S-1 . The potential of EBSD to distinguish plastic strain from creep strain is demonstrated. Misorientation development is shown to occur at a faster rate with increasing strain in plastic than in creep deformation. Similarly, the proportion of twin boundaries in service-aged steel is shown to reduce with increasing strain at a faster rate in creep than in plastic deformation. Two novel methods for creep strain estimation are proposed which utilise the disparities in the misorientation development and twin boundary reduction under the two different deformation regimes. A good correspondence is established between the strain estimates from the proposed methods and those derived from hardness measurements and digital image correlation. The methods are shown to be applicable to real power plant components through successful mapping of plastic and creep strain distributions in weldments after different periods in service.
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Williams, Valorie Sharron 1960. "In situ microviscoelastic measurements by polarization interferometry." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276691.
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A new type of computer-controlled instrument has been developed to measure microviscoelastic properties of thin materials. It can independently control and measure indentation loads and depths in situ revealing information about material creep and relaxation. Sample and indenter positions are measured with a specially designed polarization interferometer. Indenter loadings can be varied between 0.5 and 10 grams and held constant to ±41 mg. The resulting indentation depths can be measured in situ to ±1.2 nm. The load required to maintain constant indentation depths from 0.1 to 5.0 microns can be measured in situ to ±3.3 mg and the depth held constant to ±15 nm.
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Mohammadi, Yaghoub. "Compression creep measurements in pultruded angle sections made of fibre glass reinforced plastic." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69738.
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A study aimed at investigating the performance of pultruded fibre glass reinforced plastic (FGRP) materials subjected to both the time-independent and the time-dependent response of angle stubs and coupons was conducted. Angle stubs and coupons were made of isophtalic polyester resin reinforced with an E-glass fibre glass mat of 35%-45% of the weight. The stub dimensions were of 50.8 mm $ times$ 50.8 mm $ times$ 6.35 mm and their length was 305 mm. The compression coupons were cut in a prismatic shape according to ASTM Standard D695-89 with 12.70 mm $ times$ 6.35 mm cross-section and a length of 31.75 mm.In the time-independent short-term study, the FGRP angle stubs and coupons were subjected to axial compression loading with two different testing configurations.
In the time-dependent long-term study, three angle stubs were first subjected to a 350 hour preliminary creep test, followed by 150 hours of creep recovery, with three lengths and configurations of strain gauges. Finally, a last series of tests was carried out on three angle stubs instrumented with 12 5-mm long gauges. Coupon creep tests were carried out in parallel with the stub tests. The total duration of the tests was 2500 hours in creep and 250 hours in creep recovery. Results indicate a scatter in the order of 15% in creep strain measurements after 2500 hours, for both stub and coupon tests. Predictions using Findley's power law with creep parameters determined from the stub tests and coupon tests are in excellent agreement, both with one another and with actual creep strain measurements on the stubs. The Boltzman superposition principle was used to compare the experimental creep recovery results with predictions from Findley's model, and excellent agreement was also observed. (Abstract shortened by UMI.)
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Stephens, Ryan A. "Field Algae Measurements Using Empirical Correlations at Deer Creek Reservoir." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2722.
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Deer Creek Reservoir in Utah has a history of high algae concentrations. Despite recent nutrient reduction efforts, seasonal algae continue to present problems. Cost effective, accurate, and comprehensive monitoring is important to understand the reservoir processes driving this problem and characterizing the algae spatial and temporal distributions are an important part of this effort. Current laboratory methods for accurately measuring algae are expensive and time consuming and are based on water samples taken in the field and transported to the laboratory. This approach only provides data for relatively few point samples because of the time and expense of sample collection and analysis. These relatively few samples do not describe the complex spatial and temporal trends in the algal data. Algae exhibit non-uniform distributions, especially in the vertical direction. In situ probes are able to measure chlorophyll-a and provide a less expensive measuring alternative than laboratory methods. These probes provide relatively quick, high resolution vertical profile measurements, which allows for more comprehensive horizontal and temporal sampling. To have confidence in the probe data, good correlations between in situ chlorophyll-a measurements and laboratory algae or chlorophyll measurements are important, but these correlations can be reservoir and time dependant as reservoir conditions change. Therefore, they must be developed for each study site. This study reports on efforts at Deer Creek Reservoir to develop these correlations and provide a general description of the dynamic reservoir algal processes. I found that chlorophyll-a is weakly correlated to most algae species in the reservoir. However, it correlated well with total phytoplankton biovolume and the dominant algal species, which for this study was the diatom. Variations in correlation strength among the several algae species was assumed to most likely be affected by environmental factors, sample methods, algae species diversity, and the accuracy of the optical chlorophyll-a sensor. The data analysis indicate that the field methods used to obtain laboratory samples may have been a significant source of error because of the difficulty of matching the location of a probe measurement to the location of a sample. Field samples were not taken at the same depths as probe measurements and field samples from two locations were either mixed before laboratory analysis or the sample was a composite over a 2-meter range. Based on my observations, I have made several recommendations to improve the accuracy of the correlation between algae and chlorophyll-a.
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Decker, Timothy Joseph. "An assessment of water quality on Little and Big Duck Creeks near Elwood, Indiana." Virtual Press, 1987. http://liblink.bsu.edu/uhtbin/catkey/539626.
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A water quality study was conducted on Big Duck Creek and Little Duck Creek near Elwood, Indiana during the summer, autumn and winter of 1978 - 1979 and compared to measurements made in 1938.Samples were analyzed for dissolved oxygen, biochemical oxygen demand, suspended solids, ammonia, total coliform bacteria, hydrogen ion concentration and temperature. Significant differences in concentrations were observed for each environmental parameter measured in 1979 when evaluated on a basis of sampling location. With the exception of dissolved oxygen concentrations, the effect of stream volume on the concentration of environmental parameters was in most instances small.When the up and downstream stations were compared, a definite decrease in water quality was noted. The dissolved oxygen concentrations decreased as the water flowed through the city. Due to increased organic loading, the biochemical oxygen demand increased in the downstream area.Elwood increased the suspended solids level of Big Duck Creek. Agricultural and urban runoff together with untreated sewage discharges significantly increased the suspended solids level within the inner city region. Dilution by treated sewage as well as cleaner water from Little Duck Creek help reduce the suspended solids level in the downstream location. Relatively high ammonia concentrations were observed in the upstream portions of the creeks. This was apparently related to farm practices. The higher readings of ammonia were noted after animal manure was spread on the fields along the stream. The downstream levels were also high. This was probably due to ammonia in the effluents of the sewage treatment plant. In contrast, only small changes in the hydrogen ion concentration was observed throughout the creek.The number of total coliform bacteria increased in the center of town because of a sewer bypass into the creek. Below Elwood the concentration of bacteria decreased due to dilution with disinfected effluents from the sewage treatment plant.Except for a noticeable increase in biochemical oxygen demand and ammonia, the Elwood sewage treatment plant effluent together with flow from Little Duck Creek appears to improve Big Duck Creek's condition as it leaves the city to join White River.Significant differences were observed between measurements made in 1938 and 1978 - 79. Results of the study showed a significant improvement in water quality of Big Duck Creek since 1938. This was probably due to the construction of Elwood's wastewater collection system and sewage treatment plant in the 1940s.However, there was still degradation of water quality within the city due to untreated wastewater discharges. Consequently, emphasis should be focused on the inner city problem since Elwood residents would be in the proximity to this area.Department of Natural Resources
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Willard, Eric Hillman Tharsing. "Temperature and relative humidity gradients of intermittent and perennial tributaries in Northern California." [Chico, Calif. : California State University, Chico], 2009. http://hdl.handle.net/10211.4/108.
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Fiallos, Celi Diana E. "Water quality assessment of Prairie Creek Reservoir in Delaware County, Indiana." Virtual Press, 2008. http://liblink.bsu.edu/uhtbin/catkey/1391474.
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The Prairie Creek Reservoir, located in east central Indiana in an agricultural watershed, serves as a secondary drinking water source as well as a recreational facility. Limited research of water quality performed at the reservoir has affected management decisions over the past years, threatening its future.. Consequently, additional investigation was necessary to examine the reservoir dynamics, and continue to provide data to determine long-term water quality trends. Basic water quality parameters were measured using a Hydrolab Sonde, nutrients were measured spectrophotometrically, and a Secchi disk was used to determine water transparency. The Prairie Creek Reservoir was categorized as an eutrophic water body. Concentrations of the measured nutrients were higher in the hypolimnion and increased as summer progressed. Concentration of ammonia and soluble reactive phosphorus exceeded the recommended water quality guidelines. Increased concentration of phosphorus has resulted in nitrogen limitation in the reservoir. Internal loading of nutrients, especially phosphorus, was found to deteriorate water quality. Dissolved oxygen concentrations varied vertically and anoxic conditions frequently reached 50% of the total reservoir depth. Reservoir restoration and watershed protection programs need to address internal P load and nitrogen limitation to prevent development of toxic algal blooms and eutrophication in the future.Department of Natural Resources and Environmental Management
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Appel, Patrick L. "Use of Automated Sampler to Characterize Urban Stormwater Runoff in Pecan Creek." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2681/.
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The purpose of this study was to use the Global Water Stormwater Sampler SS201 to characterize the urban runoff in Pecan Creek. Location of the samplers was influenced by land use and ease of installation. Determination of the constituents for analysis was modeled after those used in the NPDES permit for seven cities within the Dallas/Ft.Worth metroplex. Some metals, notably cadmium and arsenic, exceeded the U.S. EPA's MCL's. Statistical analysis revealed first flush samples to be significantly more concentrated than composite samples. Minimum discharge loadings were found to be significantly lower than maximum discharge loadings. Additionally there were significant differences of specific constituents between station locations and storm events.
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Gottfried, Gerald J., and Daniel G. Neary. "Preliminary Assessment of Sediment Measurements at the Weir Basins at Workman Creek, Central Arizona." Arizona-Nevada Academy of Science, 2003. http://hdl.handle.net/10150/296604.
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Kikuchi, Colin. "Spatially Telescoping Measurements for Characterization of Ground Water - Surface Water Interactions along Lucile Creek, Alaska." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/202976.
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A new spatially telescoping approach was proposed to improve measurement flexibility and account for hydrologic scale in field studies of groundwater-surface water (GW-SW) interaction. We applied this spatially telescoping approach in a study GW-SW interactions along Lucile Creek, Alaska. Catchment-scale data were used to screen areas of potentially significant GW-SW exchange, indicating groundwater contribution from a deeper regional aquifer along the middle to lower reaches of the stream. This initial assessment was tested using reach-scale estimates of groundwater contribution during base flow conditions. The reach-scale measurements indicated a large increase in discharge along the middle reaches of the stream accompanied by a shift in chemical composition towards a regional groundwater end member. Point measurements of vertical water fluxes were used to evaluate spatial and temporal variability of GW-SW exchange within representative reaches. The spatially telescoping approach identified locations of GW-SW exchange and improved interpretation of reach-scale and point-scale measurements.
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Miller, Nicolas Ross. "Historic channel change on Esopus Creek, upstream of the Ashokan Reservoir, Catskills, New York." Diss., Online access via UMI:, 2009.
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Scrudato, Matthew C. "Comparison of Two Potential Streamgage Locations on Scott Creek at Swanton Pacific Ranch, California." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/330.
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Two locations on Scott Creek, located 12 miles north of Santa Cruz California, are being considered for the installation of a streamgage to measure discharge. Each location offers unique considerations and challenges in gage construction and discharge measurement capabilities. A detailed flood frequency analysis was completed using a direct watershed comparison, direct equations developed by Waananen and Crippen, a Log Pearson Type III Frequency Distribution, a regional analysis, and two-station comparisons. Final results indicate a 100-year recurrence interval of 6,310 ft3/s at the Upper Scott Creek location and 6,520 ft3/s at the lower location. A detailed indirect measurement revealed that the Lower Scott Creek gage location can only maintain a discharge of 2,500 ft3/s, or a 10-year frequency event, before bank overflow. Therefore, a cableway spanning the width of the design flow cannot be constructed and stage readings at extreme peak events will not accurately represent the true hydrograph. A bridge at the Upper Scott Creek gage location will provide a means for measuring high flow events; however, the channel is in a state of disequilibrium due to debris jams within the 140 foot reach above the bridge. This site is also problematic due to the occurrence of channel avulsion which is scouring and incising a new channel which threatens to undermine the left bank wingwall of the bridge. Remediation measures have been proposed, including the installation of a cross-vane and wing-deflectors, to mitigate negative effects of erosion and reestablish a natural channel condition. The upstream location has been selected as the preferred alternative given the remediation measures are successful.
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Shaheen, Ehab T. "Long Term Performance of Corrugated HDPE Pipes Produced with Post-Consumer Recycled Materials Under Constant Deflection." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1541422245636659.
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Boudreau, Jonna. "New methods for evaluation of tissue creping and the importance of coating, paper and adhesion." Doctoral thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-29317.
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The creping process and the conditions on the Yankee cylinder dryer are key factors in a tissue paper mill, and they therefore need to be kept under good control in order to maintain a high and uniform quality. To this end it would be valuable to be able to make on-line measurements of Yankee coating thickness as well as the crepe structure of the tissue paper. The adhesion of paper to the cylinder affects the creping process and more information about the parameters that affect the adhesion is therefore of interest. To perform trials on a full scale or in a pilot plant is very costly and laboratory creping equipment is therefore sought after in order to be able to measure the adhesion force. The coating layer for use on the cylinder was analysed. It contained a large amount of carbohydrates and could not be considered transparent. The thickness of the coating layer was measured on a laboratory cylinder with a method based on fluorescence. An optical brightener was added to the coating chemicals and the coating layer was subjected to UV-radiation. The intensity of the light emitted by the optical brightener was measured and gave an indication of the thickness of the coating layer. The equipment has to be further investigated before it is possible to implement the new sensor on-line. New creping equipment and an adhesion method were developed for use on a laboratory scale. The equipment can operate with different creping angles and the force needed to crepe the paper can be measured. The highest creping force was obtained for papers of high grammage, low dryness at adhesion, high drainability, high fines content and high hemicellulose content. A more direct method is to analyse the structure of the produced paper. Measurements were made on a tissue paper with an optical fibre sensor while the paper was travelling at low speed. The collected signal was mathematically analysed and the characteristic wavelength was calculated for different paper samples. These values were close to the wavelengths measured with an off line method by a commercial crepe analyser.Baksidestext The creping process is the heart of tissue paper manufacture. To control the process better, on-line measurements of paper structure and coating thickness are sought after. The creping is highly dependent on the adhesion of the paper to the Yankee dryer. To be able to measure the adhesion, laboratory creping equipment was also required. Different pulp parameters affect the adhesion and some of them have been investigated in this work. The coating on the Yankee cylinder consisted mainly of fiber fragments and could not be considered as transparent, which had to be considered when choosing a method to measure coating thickness. A method based on the light emitted from an optical brightener in the coating when subjected to UV-irradiation was used, but has to be further improved before it can be used on-line. A new laboratory creping method was developed to determine the adhesion between paper and metal, and the force needed to scrape off the paper with a doctor blade was measured. The highest creping force was obtained for papers made of pulp with a high drainability, high fines content and high hemicellulose content. An optical method using reflected light to measure crepe wavelength on-line was developed. The paper travelled under a sensor and the light collected was mathematically analyzed to determine the most common wavelength.
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Jailin, Thomas. "Étude expérimentale et modélisation du comportement d’un tube de gainage lors d’un accident de réactivité en phase post-crise ébullition." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI032.
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Cette thèse porte sur le comportement au fluage du tube de gainage en Zircaloy-4 en conditions représentatives de la phase post-DNB (Departure from Nucleate Boiling) d’un accident de réactivité (RIA). Ces conditions peuvent se résumer à une élévation brutale de la température de la gaine alors que celle-ci est intérieurement pressurisée, suivie de son ballonnement à haute température. La transformation de phase (α→β) du Zircaloy-4 a tout d’abord été étudiée à l’aide d’essais de dilatométrie pour des vitesses de chauffe comprises entre 50 et 2000°C/s. Une attention particulière a été portée aux moyens de mesure thermiques, particulièrement délicats à mettre en place sous transitoires rapides. La microstructure du matériau a également été analysée à l’aide d’essais trempés. Les résultats ont permis de caractériser un modèle de changement de phase valide de l’équilibre thermique jusqu’à des vitesses de 2000°C/s, basé sur une description de Leblond. Dans un deuxième temps, la plateforme d’essai thermomécanique ELLIE de l’INSA Lyon a été adaptée de façon à pouvoir simuler les conditions de chargement d’un post-DNB. Des essais de fluage en ballonnement ont été réalisés avec des vitesses de chauffe de 1200°C/s. Le domaine de température étudié s’étend de 840 à 1020°C. avec des pressions internes de 7 et 11 bar. Les champs de déplacements et de températures sont mesurés en surface de l’éprouvette, respectivement par stéréo-corrélation d’images numériques et thermographie proche infrarouge. Une procédure a été développée, afin d’obtenir ces champs à l’aide des deux mêmes caméras. Les essais ont mis en évidence un comportement au fluage complexe dans le domaine biphasé, qui semble étroitement lié à la proportion de phase dans le matériau. Un fort impact de la vitesse de chauffe sur la tenue mécanique de la gaine a également été observé, avec des vitesses de déformation bien plus importantes suite à un transitoire thermique rapide. Enfin, la méthode de recalage par éléments finis (FEMU) a été mise en place, afin d’identifier une loi de comportement en exploitant toute la richesse des essais. Le modèle éléments finis de l’éprouvette est basé sur une représentation 3D de la zone d’intérêt contrainte par une hypothèse de Love-Kirchhoff dans la section. Une loi de fluage, couplée à la fraction de phase, a été identifiée, et permet de représenter le comportement de la gaine pendant les 10 premières secondes des essais sur l’ensemble des conditions testées. Une ouverture qui vise à prendre en compte l’influence de la taille des grains sur le fluage est finalement proposée en vue de modéliser les essais sur un temps supérieur à 10 secondesDuring the post-DNB (Departure from Nucleate Boiling) phase of a reactivity initiated accident (RIA), the fuel cladding temperature may increase very steeply (1000°C/s) up to temperatures of around 900°C while the clads are internally pressurized. All these conditions lead to the ballooning of the fuel rod until its potential burst. This work aims at characterizing the creep behavior of the Zircaloy-4 cladding under such conditions. In a first part, the (α→β) phase transformation of the material was studied upon fast heating rates. Dilatometry tests were performed with heating rates ranging from 50 to 2000°C/s. Special care was taken to the thermal measurements, to achieve sufficient accuracy under fast thermal transients. The material microstructure was also analyzed on quenched specimens. All these results enabled a phase transformation model to be characterized, based on a Leblond’s formulation. In a second part, the experimental device ELLIE was updated to reproduce simulated thermo-mechanical post-DNB conditions on fuel cladding sections. Creep ballooning tests were performed with well controlled thermal transients of about 1200°C/s. Around twenty tests were carried out in simulated post-DNB conditions with internal pressures of 7 and 11 bar and for temperatures of interest ranging from 840 to 1020°C. Kinematic and thermal full-fields were obtained on the sample surface by stereo-correlation and near infrared thermography, respectively. A method was developed to obtain these two kinds of fields using the same two cameras. The tests performed highlighted a complex creep behavior in the two-phase domain, which appears to be closely correlated to the phase fraction within the material. A strong impact of the heating rate on the creep properties was also observed, with much higher strain rates following a high thermal transient. The finite element model updating (FEMU) method was used to identify the creep behavior of the cladding. The finite element model is based on a 3D representation of the region of interest seen by the cameras. A Love-Kirchhoff kinematic was imposed through the clad section using the kinematic field obtain by stereo-correlation. The identification method was first validated on a virtual case, and then enabled a creep law to be characterized, coupled to the phase fraction within the material. The model thus identified reproduced the creep rates well during the first ten seconds of the tests. A final study proposes to include a grain growth contribution in the creep law
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Podesta, Laurie. "Etude expérimentale de la fissuration en fluage de l'acier 316H vieilli sous environnement CO2." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTS011/document.
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Des fissures intergranulaires ont été observées sur des composants évoluant dans un environnement CO2 à haute température (550°C). Le matériau, un acier austénitique inoxydable de nuance 316H, est soumis à des sollicitations en fluage. L'objectif de la thèse est de permettre une meilleure compréhension du mécanisme d'endommagement par fluage et des effets de l'environnement sur l'apparition et la propagation de ces fissures. Une synergie entre la simulation par éléments finis et la mesure de champs cinématiques au moyen de la Corrélation d'Images Numériques (CIN) a été créée pour aborder ce problème avec une approche locale, à l'échelle de la microstructure. Une méthode de CIN adaptée au suivi de la fissuration basée sur l'utilisation des expressions de la Mécanique Linéaire Elastique de la Rupture a été développée. Une validation expérimentale sur essai de traction in-situ sur microéprouvettes pré-fissurées de matériau 316H est proposéeAt elevated temperature (550°C) in CO2 environment, intergranular creep cracks have been observed in thermally and environmentally aged 316H austenitic stainless steel. The objective of this work is to enhance the understanding of the creep crack mechanism and the effects of environment on crack initiation and growth. Some microtests on Single Edge Notched Tensile specimen (SENT) have been performed to better describe the interaction between chemistry and mechanics at the microstructural scale. A creep crack monitoring procedure using Digital Image Correlation (DIC) have been developped and assessed using Finite Element Modelling (FEM) of cracked bi-crystal. Based on a projection on Linear Elastic Fracture Mechanics expressions, the crack parameters (crack tip position, orientation) can be determined and the growth can be measured. A validation on in-situ tensile tests on SENT 316H specimen is proposed
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Wood, Matthew Lawton. "Streamflow Analysis and a Comparison of Hydrologic Metrics in Urban Streams." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/769.
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This study investigates the hydrologic effects of urbanization in two Portland, Oregon streams through a comparison of three hydrologic metrics. Hydrologic metrics used in this study are the mean annual runoff ratio (Qa), mean seasonal runoff ratio (Qw and Qd), and the fraction of time that streamflow exceeds the mean streamflow during the year (TQmean). Additionally, the relative change in streamflow in response to storm events was examined for two watersheds. For this investigation urban development is represented by two urbanization metrics: percent impervious and road density. Descriptive and inferential statistics were used to evaluate the relationship between the hydrologic metrics and the amount of urban development in each watershed. The effect of watershed size was also investigated using nested watersheds, with watershed size ranging from 6 km2 to 138km 2. The results indicate that annual and seasonal runoff ratios have difficulty capturing the dynamic hydrologic behavior in urban watersheds. TQmean was useful at capturing the flashy behavior of the Upper Fanno watershed, however it did not perform as well in Kelley watershed possibly due to the influence of impermeable soils and steep slopes. Unexpected values for hydrologic metrics in Lower Johnson, Sycamore and Kelley watersheds could be the result water collection systems that appear to route surface water outside of their watersheds as well as permeable soils. Storm event analysis was effective at characterizing the behavior for the selected watersheds, indicating that shorter time scales may best capture the dynamic behavior of urban watersheds.
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Ng, Lawrence Kiam Yam Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "A new multiaxial creep damage model based on the exhaustion of internal energy." 2007. http://handle.unsw.edu.au/1959.4/40733.
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The creep of materials is a research topic of major significance in the life assessment and design of many modern engineering components of advance technology such as: power generation plant, chemical plant, gas turbines, jet engines, spacecrafts, components made of plastics and polymers, etc. To predict the creep lives of such components, one necessary ingredient is a creep damage model. The current creep damage models are either too cumbersome to be readily employed and/or not sufficiently accurate for practical applications. This thesis describes a new creep damage model to overcome some of the major shortcomings in current creep damage/life prediction methods. The proposed model is relatively simple and readily applicable to industrial cases yet it is sufficiently accurate. The proposed model assumes that, on a macroscopic level, the energy dissipated in the material may be taken as a measure of creep damage induced in the material. In another words, creep damage is directly proportional to the absorbed internal energy density (IED), i.e., the internal energy per unit of volume. In this way, the model takes into account both multiaxial loading and deformation. The model is formulated when the creep constitutive relationships may be expressed by primary plus steadystate or steady-state alone (IED-SS) as well as for the cases when the material behaviour includes the creep tertiary region (IED-T). The proposed model has been verified by applying it to various components for which the experimental creep lives are available from literature including thick/thin cylindrical vessels, notch bars with various notch-root radii and materials, multi-material cross welds bars, and perforated biaxial plates. The predicted creep lives of these components by the proposed model (IED-SS and IED-T) are compared with the experimental results and those obtained by the Reference Stress Method (RSM). It is shown that the maximum errors in relation to the creep lives of the above-mentioned components are: 18% when IED-SS is applied, 38% when IED-T is applied, and 301% when RSM is applied. To estimate the effects of uncertainties in material data on the predicted creep life, a sensitivity analysis has been conducted. To this end and in relation to Norton creep law, material parameters such as creep stress coefficient and stress exponent are considered. In addition, the sensitivity analysis included the uncertainties related to the uniaxial creep rupture data. As might be expected, the results suggest that the predicted creep life is most sensitive to the creep stress. Finally, the present research reveals that the proposed model is simple, practical and can be used in conjunction with any commercial finite element code with creep analysis capabilities.
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LaManna, James Anthony. "Measurement of material creep parameters of amorphous selenium by nanoindentation and the relationship between indentation creep and uniaxial creep." 2004. http://etd.utk.edu/2004/LaMannaJames.pdf.
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Thesis (M.S.)--University of Tennessee, Knoxville, 2004.Title from title page screen (viewed Sept. 21, 2004). Thesis advisor: George M. Pharr. Document formatted into pages (xii, 130 p. : ill. (some col.)). Vita. Includes bibliographical references (p. 96-98).
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Lee, Jonghyun. "Non-contact measurement of creep resistance of ultra-high-temperature materials." 2007. https://scholarworks.umass.edu/dissertations/AAI3254917.
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Continuing pressures for higher performance and efficiency in energy conversion and propulsion systems are driving ever more demanding needs for new materials which can survive high stresses at the elevated temperatures. In such severe environments, the characterization of creep properties becomes indispensable. Conventional techniques for the measurement of creep are limited to about 1,700°C. A new method which can be applied at temperatures higher than 2,000°C is strongly demanded. This research presents a non-contact method for the measurements of creep resistance of ultra-high-temperature materials. Using the electrostatic levitation (ESL) facility at NASA MSFC, a spherical sample was rotated quickly enough to cause creep deformation due to the centripetal acceleration. The deformation of the sample was captured with a digital camera, and the images were then analyzed to measure creep deformation and to estimate the stress exponent in the constitutive equation of the power-law creep. To compare experimental results, numerical and analytical analyses on creep deformation of a rotating sphere have been conducted. The experimental, numerical, and analytical results showed a good agreement with one another.
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Lu, Cheng-Hua, and 呂承樺. "The Measurement of Time and Temperature of Al and Al Alloy Thin Film Creep Behavior Using Bulge Test." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/11436297610556705693.
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Vorobyev, Alexey. "Datorstödda mättekniker i fält av sprickor i limträbalkar." Thesis, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-58981.
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Cracks in wood are considered to be one of the major problems for products, which have been made from this material. Crack detection and its propagation methods should be revised and improved with application of modern techniques. Nowadays new measuring techniques like digital camera image processing, and 3-D laser scanning are available. This work describes computer aided in-field methods for registration cracks in wood, its propagation, and tracing dimensional stability of glued laminated beams. The benefits of different methods for supervision of wooden element as well as its limitations are discussed.Validerat; 20120608 (anonymous)
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Campos, Miguel Souto. "Desenvolvimento de sistemas experimentais para estudo do comportamento do betão sob condições de retração restringida." Master's thesis, 2013. http://hdl.handle.net/1822/30971.
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Dissertação de mestrado integrado em Engenharia Civil (área de especialização em Perfil de Estruturas e Geotecnia)As estruturas de betão estão, ao longo da sua vida, sujeitas a variações de volume, provocadas por diversos efeitos, tal como a retração e as mudanças de temperatura. No caso de estruturas cujas deformações volumétricas se encontram parcial ou totalmente restringidas, geram-se esforços internos associados às deformações impostas. Dado que estes esforços internos correspondem frequentemente a trações e atingem a capacidade resistente do betão, ocorre fissuração. A armadura necessária para controlo da abertura destas fendas é frequentemente significativa, acarretando também custos relevantes. De facto, a regulamentação existente para definição da armadura de controlo da retração (p.ex. CEN (2004a)) é extremamente simplificada e muitas vezes conservativa. Por outro lado, é ainda inexistente regulamentação, recomendações, ou até trabalhos científicos relativos ao controlo de fissuração de retração com o uso combinado de armaduras convencionais e fibras discretas. Tendo em conta a especial adequabilidade do uso de fibras discretas para apoio ao controlo de fissuração, considerou-se que esta era uma relevante oportunidade de investigação para a presente dissertação. Neste contexto o estudo das estruturas impedidas de se deformarem envolve uma complexa interação entre a retração e a fluência. Para a compreensão destas componentes é frequente recorrerse a ensaios de restrição ativa à deformação, cujo processo envolve a utilização de dispositivos que permitam controlar o grau de restrição num provete, impedindo-o de retrair livremente (normalmente designados por TSTM, Temperatura Stress Testing Machine). No decorrer da dissertação, serão apresentados vários sistemas de ensaio, dando especial atenção aos atuadores e sistemas de medição utilizados. A dissertação compreende também uma revisão bibliográfica detalhada sobre sistemas atuadores alternativos aos normalmente utilizados (hidráulicos), com o propósito de acarretarem custos mais reduzidos. No contexto desta dissertação são reportadas alterações ao sistema de ensaio existente na Universidade do Minho, desenvolvido por De Sousa (2011), preparado para a condução de ensaios sobre provetes de betão simples e armado, denominado por VRF, Variable Restraint Frame. As alterações envolveram a elaboração de um novo sistema de medição de deformações, um novo molde e a validação do comportamento do cilindro hidráulico utilizado. Posteriormente, é apresentado um novo sistema, análogo ao VRF, com a particularidade de envolver a reutilização de peças existentes no laboratório da U.M. e permitir encurtar os custos associados. O sistema utiliza como atuador o aperto/desaperto de uma ligação parafuso-porca e a medição das deformações é executada através da captação de imagens, por parte de um microscópio USB, dum sistema de lamelas micrométricas sobrepostas.
The concrete structures are, throughout their life, subject to changes in volume caused by various effects such as the shrinkage and temperature variations. In the case of volumetric structures whose deformations are partially or fully restricted, internal stresses are generated associated with the imposed deformations. Since these internal stresses often correspond to tensile forces and reach the bearing capacity of the concrete, cracking occurs. The reinforcement needed to control the opening of these cracks is often significant, also causing substantial costs. Indeed, the existing codes of reinforcement to control shrinkage regulation (eg: CEN (2004a)) is extremely simplified e often conservative. On the other hand, is still missing regulations, recommendations, or even scientific studies concerning the shrinkage cracking control with the combined use of conventional reinforcements and discrete fibers. Given the particular the special use of discrete fibers to assist in the control cracking, it was considered that this was a relevant research opportunity for this thesis. In this context the study of structures restrained to deforming involves a complex interaction between shrinkage and creep. For the understanding of these components often are used tests of active restraint to deformation, whose process involves the use of devices which control the degree of restriction in a specimen, preventing it of shrink freely (usually designated as TSTM, Temperature Stress Testing Machine). A number of test systems will be presented, with special regard to the use of loading and measurement systems, during the dissertation. The dissertation includes a detailed literature review on alternative loading systems to those usually used (hydraulics), with the purpose of igniting lower costs. In the context of this thesis will be reported changes to the existing test system developed by De Sousa (2011) at Universidade do Minho, prepared to conduct tests on specimens of plain and reinforced concrete, called VRF, Variable Restraint Frame. The changes wrapped the development of a new system for strain measurement, a new mold and validation of the behavior of the hydraulic cylinder used. Posteriorly, a new system is presented, analogous to VRF, with the peculiarity of involving the reuse of existing parts in the U.M. lab and allow shortening the costs. The system uses as loading the tightening / loosening of a screwnut connection and the measurement of the deformation is performed through capturing images, by a USB microscope, of a system of overlapping micrometric lamellae.
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Canepari, Stacy M. "Containerless Measurements of High Temperature Material Properties." 2009. https://scholarworks.umass.edu/theses/321.
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Currently, the design of high temperature mechanical components is limited by material performance at elevated temperatures. Rocket nozzle materials, for example, need to survive exhaust gas temperatures up to 3000 ºC under high stresses for short periods of time. Additionally, one of the current challenges in hypersonic flight is the development of materials that will withstand the leading edge temperatures which exceed 2700 ºC. In these severe environments, the characterization of materials’ creep properties is essential.
Conventional creep testing methods are limited to 1700°C. Using ESL, a group of researchers at the University of Massachusetts Amherst developed a non-contact creep method, which is not subject to such temperature limits. Using the non-contact method a spherical sample is rotated rapidly, and the driving load is applied by centripetal acceleration, which causes deformation. During previous creep tests, a laser supplied both the heating and driving rotational force to the sample. Since the rotation is controlled by the photon pressure emitted from the heating laser, the applied stress is coupled to the testing temperature. By developing an independent rotation control, non-contact creep tests could be conducted on a wider range of materials. A specialized high-speed induction motor was developed for use in high-temperature creep tests.
In addition to creep behavior, the understanding of thermophysical properties is important for the emerging class of high temperature material. Using a previously developed method, non-contact density measurements were taken concurrently on the same materials as X-ray diffraction measurements. Over 35 materials were successfully processed including, aluminum, copper, hafnium, palladium, nickel, titanium and zirconium based alloys. Besides contributing to high temperature material databases, density measurements provide an understanding of solidus formation and short-range order in the liquid state.
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Kirkham, Tracie. "Peakflow causative mechanisms and frequencies at Reynolds Creek, southwestern Idaho /." 2002. http://hdl.handle.net/1957/9677.
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Cheng, Wen-Ching, and 張汶璟. "Building a method of discharge measurement Nanshih Creek at Lansheng Bridge." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/6pntv8.
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碩士國立臺北科技大學
土木與防災研究所
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The discharge measurement is foundation of scientific research, water resource management and reservoir operation. The Nanshih creek is major supply water source in the Taipei urban. Hence, the research was measured discharge in Nanshih creek at Lansheng Bridge. In the duration of normal discharge, the Price AA was used for discharge measurement. In the duration of flood stages, the ADP was used. Both measurement have water depth and flow velocity. The discharge was calculated by Mid-Section Method. Through the extended measurement work, those established high validity and realizable stage-discharge rating curve in normal discharge duration. The measurement data can support further application. Through the relationship of maximum velocity and mean velocity can reduce staffs exposed in the dangerous environment. Also, it can make discharge measurement more efficiently in the flood duration. The validity and realizable discharge data could improved construction cost. The easy discharge measurement method means more data can collected in the same time.
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Xu, Yan Fan, University of Western Sydney, College of Health and Science, and School of Biomedical and Health Sciences. "Study of selected water quality parameters at Narellan Creek." 2006. http://handle.uws.edu.au:8081/1959.7/17957.
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A two-year study was conducted at the Narellan Creek Catchment between September 1998 and August 2000. To improve the quality of the water that flows in to the Nepean River, the Harrington Park retention basin was enlarged and rehabilitated from 7.0 ha to 12.0 ha area. This study measured several parameters of water quality to assess the efficiency of the Harrington Park retention basin for water quality improvement. Three sampling sites – the Camden Valley Way (CVW), Harrington Park retention basin (HPK) and Kirkham Lane (KLN) were selected for sample collection. Water flows from CVW to HPK then to KLN and finally to the Nepean River. Rainfall, water level, discharge rate and ambient temperature were recorded at the KLN site while the selected water quality parameters were determined at all the three sites. Low flow samples were manually collected at monthly intervals. An auto-sampler which collected water samples during rain events (for high flow data) was set up at the KLN site. Rising stage samplers which collected water at different water levels during a rain event, was set up at all the sites but data from this device was found to be of limited use due to the varying time lags between the filling of each bottle. Statistical analyses by various measures show that the Harrington Park retention basin played a significant role in improving the upstream and in-stream water quality. These study shows that constructed wetlands like the Harrington Park retention basin has the ability to significantly improve the water quality of a catchment. The water quality improvement is greater at lower water flow rates.Doctor of Philosophy (PhD)
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Keaney, Francis Bartholomew. "Stream channel stability and channel evolution in a rapidly urbanizing, ridge-and valley watershed, Beaver Creek, Knox County, Tennessee." 2009. http://trace.tennessee.edu/utk_gradthes/536.
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Dent, Elizabeth F. "Influence of hillslope and instream processes on channel morphology of Esmond Creek in the Oregon Coast Range /." 1993. http://hdl.handle.net/1957/9491.
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Arik, Aida D. "A study of stream temperature using distributed temperature sensing fiber optics technology in Big Boulder Creek, a tributary to the Middle Fork John Day River in eastern Oregon." Thesis, 2011. http://hdl.handle.net/1957/26338.
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The Middle Fork John Day Basin in Northeastern Oregon is prime habitat for spring Chinook salmon and Steelhead trout. In 2008, a major tributary supporting rearing habitat, Big Boulder Creek, was restored to its historic mid-valley channel along a 1 km stretch of stream 800 m upstream of the mouth. Reduction of peak summer stream temperatures was among the goals of the restoration. Using Distributed Temperature Sensing (DTS) Fiber Optic Technology, stream temperature was monitored prior to restoration in June 2008, and after restoration in September 2008, July 2009, and August 2009. Data gathered was used to determine locations of groundwater and hyporheic inflow and to form a stream temperature model of the system. The model was used both to develop an evaluation method to interpret components of model performance, and to better understand the physical processes important to the study reach.
A very clear decreasing trend in surface temperature was seen throughout each of the DTS stream temperature datasets in the downstream 500 m of the study reach. Observed reduction in temperature was 0.5°C (±0.10) in June 2008, 0.3°C (±0.37) in September 2008, 0.6°C (±0.25) in July 2009, and 0.2°C (±0.08) in August 2009. Groundwater inflow was calculated to be 3% of the streamflow for July 2009 and 1% during the August 2009 installation. Statistically significant locations of groundwater and hyporheic inflow were also determined.
July 2009 data was used to model stream temperature of the 1 km (RMSE 0.28°C). The developed model performance evaluation method measures timelag, offset, and amplitude at a downstream observed or simulated point compared with the boundary condition, rather than evaluating the model based on error. These measures are
particularly relevant to small scale models in which error may not be a true reflection of the ability of a model to correctly predict temperature. Breaking down model performance into these three predictive measures was a simple and graphic method to show the model's predictive capability without sorting through large amounts of data. To better understand the model and the stream system, a sensitivity analysis was conducted showing high sensitivity to streamflow, air temperature, groundwater inflow, and relative humidity. Somewhat surprisingly, solar radiation was among the lowest sensitivity. Furthermore, three model scenarios were run: a 25% reduction in water velocity, a 5°C increase in air temperature, and no groundwater inflow. Simulations of removal of groundwater inflows resulted in a 0.5°C increase in average temperature over the modeled time period at the downstream end, further illustrating the importance of groundwater in this stream system to reduce temperatures.Graduation date: 2012
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Johnstone, Joseph A. "Nitrogen, Phosphorus and Carbon Dynamics during Storms in a Glaciated Third-Order Watershed in the US Midwest." Thesis, 2013. http://hdl.handle.net/1805/3460.
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Indiana University-Purdue University Indianapolis (IUPUI)The characterization of the nutrients nitrogen, phosphorus and carbon (NPC) export to streams during storms is an integral part of understanding processes affecting water quality. Despite the fact that excessive levels of these nutrients in the Mississippi River basin adversely affects water quality in the Gulf of Mexico, little research has been conducted on NPC dynamics during storms on larger (>20 km2) agriculturally dominated Midwestern watersheds. This project examined the storm export of nitrate, ammonium, total phosphorus, and dissolved organic carbon (DOC) in the upper Eagle Creek Watershed (UECW) (274 km2) in Central Indiana, USA. Water samples were collected during five winter and spring storms in 2007 and 2008 on the rising and falling limb of the hydrograph, in order to characterize NPC dynamics during storm events. Stream discharge and precipitation was monitored continuously, and major cations were used to examine changes in source water over the duration of the storm and assist in the determination of potential flowpaths. DOC, total P, and TKN (Total Kjeldahl Nitrogen) tended to peak with discharge, while nitrate usually exhibited a slight lag and peaked on the receding limb. Total phosphorus, NH3-, TKN, and DOC appear to be delivered to the stream primarily by overland flow. NO3--N appear to be delivered by a combination of tile drain and macropore flow. Overall UECW displayed smoother nutrient export patterns than smaller previously studied watersheds in the area suggesting that scale may influence nutrient export dynamics. Further research is underway on a 3000 km2 watershed in the area to further examine the role scale may play in nutrient export patterns.
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Piemonti, Adriana Debora. "Effect of Stakeholder Attitudes on the Optimization of Watershed Conservation Practices." Thesis, 2013. http://hdl.handle.net/1805/3219.
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Indiana University-Purdue University Indianapolis (IUPUI)Land use alterations have been major drivers for modifying hydrologic cycles in many watersheds nationwide. Imbalances in this cycle have led to unexpected or extreme changes in flood and drought patterns and intensities, severe impairment of rivers and streams due to pollutants, and extensive economic losses to affected communities. Eagle Creek Watershed (ECW) is a typical Midwestern agricultural watershed with a growing urban land-use that has been affected by these problems. Structural solutions, such as ditches and tiles, have helped in the past to reduce the flooding problem in the upland agricultural area. But these structures have led to extensive flooding and water quality problems downstream and loss of moisture storage in the soil upstream. It has been suggested that re-naturalization of watershed hydrology via a spatially-distributed implementation of non-structural and structural conservation practices, such as cover crops, wetlands, riparian buffers, grassed waterways, etc. will help to reduce these problems by improving the upland runoff (storing water temporally as moisture in the soil or in depression storages). However, spatial implementation of these upland storage practices poses hurdles not only due to the large number of possible alternatives offered by physical models, but also by the effect of tenure, social attitudes, and behaviors of landowners that could further add complexities on whether and how these practices are adopted and effectively implemented for benefits. This study investigates (a) how landowner tenure and attitudes can be used to identify promising conservation practices in an agricultural watershed, (b) how the different attitudes and preferences of stakeholders can modify the effectiveness of solutions obtained via classic optimization approaches that do not include the influence of social attitudes in a watershed, and (c) how spatial distribution of landowner tenure affects the spatial optimization of conservation practices on a watershed scale. Results showed two main preferred practices, one for an economic evaluation (filter strips) and one for an environmental perspective (wetlands). A land tenure comparison showed differences in spatial distribution of systems considering all the conservation practices. It also was observed that cash renters selected practices will provide a better cost-revenue relation than the selected optimal solution.