Tesis sobre el tema "Sandy"
Siga este enlace para ver otros tipos de publicaciones sobre el tema: Sandy.
Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros
Consulte los 50 mejores tesis para su investigación sobre el tema "Sandy".
Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.
También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.
Explore tesis sobre una amplia variedad de disciplinas y organice su bibliografía correctamente.
1
Bernardi, Lorenzo. "Centrifuge Modeling of Sandy Slopes". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amslaurea.unibo.it/125/.
Texto completoResumen
Slope failure occurs in many areas throughout the world and it becomes an important problem when it interferes with human activity, in which disasters provoke loss of life and property damage.
In this research we investigate the slope failure through the centrifuge modeling, where a reduced-scale model, N times smaller than the full-scale (prototype), is used whereas the acceleration is increased by N times (compared with the gravity acceleration) to preserve the stress and the strain behavior.
The aims of this research “Centrifuge modeling of sandy slopes” are in extreme synthesis:
1) test the reliability of the centrifuge modeling as a tool to investigate the behavior of a sandy slope failure;
2) understand how the failure mechanism is affected by changing the slope angle and obtain useful information for the design.
In order to achieve this scope we arranged the work as follows:
Chapter one: centrifuge modeling of slope failure. In this chapter we provide a general view about the context in which we are working on. Basically we explain what is a slope failure, how it happens and which are the tools available to investigate this phenomenon. Afterwards we introduce the technology used to study this topic, that is the geotechnical centrifuge.
Chapter two: testing apparatus. In the first section of this chapter we describe all the procedures and facilities used to perform a test in the centrifuge. Then we explain the characteristics of the soil (Nevada sand), like the dry unit weight, water content, relative density, and its strength parameters (c,φ), which have been calculated in laboratory through the triaxial test.
Chapter three: centrifuge tests. In this part of the document are presented all the results from the tests done in centrifuge. When we talk about results we refer to the acceleration at failure for each model tested and its failure surface. In our case study we tested models with the same soil and geometric characteristics but different angles. The angles tested in this research were: 60°, 75° and 90°.
Chapter four: slope stability analysis. We introduce the features and the concept of the software: ReSSA (2.0). This software allows us to calculate the theoretical failure surfaces of the prototypes. Then we show in this section the comparisons between the experimental failure surfaces of the prototype, traced in the laboratory, and the one calculated by the software.
Chapter five: conclusion. The conclusion of the research presents the results obtained in relation to the two main aims, mentioned above.
2
何敏泉 y Man-chuen Anthony Ho. "A hospice in Sandy Bay". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31982414.
Texto completo
3
Ho, Man-chuen Anthony. "A hospice in Sandy Bay". Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25946043.
Texto completo
4
Siegfanz-Strauß, Sandy [Verfasser]. "Tarifrecht im Betriebsübergang / Sandy Siegfanz-Strauß". Baden-Baden : Nomos Verlagsgesellschaft mbH & Co. KG, 2017. http://d-nb.info/1160486832/34.
Texto completo
5
Roberts, Tiffany. "Natural and Anthropogenic Influences on the Morphodynamics of Sandy and Mixed Sand and Gravel Beaches". Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4216.
Texto completoResumen
Beaches and coastal environments are dynamic, constantly shaped and reshaped by natural processes and anthropogenic modifications. The morphodynamics and influence of natural and anthropogenic factors of two different coasts at various temporal and spatial scales are discussed.
To quantify the performance of several beach nourishment projects at annual temporal and kilometer spatial scales on three adjacent microtidal low-wave energy barrier islands in west-central Florida, a total of 5,200 beach and nearshore-profiles spaced at 300 m were surveyed monthly to bi-monthly from 2006-2010. Beach nourishment performance is most significantly influenced by the interruption of longshore sediment transport by complex tidal-inlet processes. More specifically, the tidal-inlet processes influencing adjacent beach nourishment performance includes longshore transport interruption resulting from divergence induced by wave refraction over an ebb-tidal shoal, flood-tidal currents along the beach, and total littoral blockage by structured inlets. A morphologic indicator of a large longshore transport gradient within the study area is the absence of a nearshore sandbar. These non-barred beaches are characterized by persistent shoreline erosion and were almost exclusively located in areas with a large longshore transport gradient. The more typical beach state along the three barrier islands was one exhibiting a migratory bar and relatively stable shoreline. The presence of a sandbar indicates the dominance of cross-shore processes, with onshore migration during calm wave conditions and offshore migration during energetic wave conditions. The onshore and offshore migration of the sandbar is closely related to non-stormy summer and stormy winter seasonal beach changes, respectively.
The morphodynamics of a mixed sand and gravel beach in Delaware were investigated based on 740 beach profiles surveyed almost monthly from 2009 to 2011, 60 sediment cores, and 550 surface sediment samples collected at various alongshore and cross-shore transects. Inter-seasonal temporal scales of storm-induced beach changes and post-storm recovery were examined based on a hurricane, a typical energetic winter storm, and an extremely energetic storm resulting from the rare collision of a hurricane and winter storm ("Nor'Ida") occurring within a 3-month period in 2009. The mixed sand and gravel beaches in Delaware are characterized by monotonically increasing water depths lacking a sandbar under all wave conditions. A distinctive beach cycle was identified consisting of a built-up berm profile and depleted nearly-planar storm profile, with a time-scale related to the frequency and intensity of storm impact and duration of intra-storm recovery instead of simple seasonality. The sedimentological characteristics of the storm deposit associated with Nor'Ida demonstrated substantial cross-shore variation ranging from sandy-gravel and gravelly-sand within the storm swash zone (near the pre-storm dune edge) to well-sorted medium to coarse sand seaward of the storm swash zone, suggesting that storm deposits along mixed beaches demonstrate a variety of sedimentological characteristics. A new dynamic beach cycle model is proposed for the non-barred mixed sand and gravel beach with temporal variability controlled by storm occurrence and inter-storm duration.
6
Glückstein, Sandy [Verfasser]. "Wissensmanagement - Eine neo-institutionalistische Perspektive / Sandy Glückstein". München : GRIN Verlag, 2009. http://d-nb.info/1186255706/34.
Texto completo
7
Carrillo-Gonzalez, Rogelio. "Mechanisms of Zn displacement through sandy soils". Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312559.
Texto completo
8
Alkhalidi, Mohamad. "Sediment transport in sandy estuaries at equilibrium". [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010108.
Texto completo
9
Jazayeri, Shoushtari Seyed Mohammad Hossein. "Groundwater Dynamics in a Sandy Unconfined Aquifer". Thesis, Griffith University, 2016. http://hdl.handle.net/10072/367171.
Texto completoResumen
Groundwater dynamics in a sandy unconfined aquifer have been investigated through laboratory experiments and numerical modelling. The laboratory experiments on the propagation of groundwater waves have yielded new insights into underlying physics. Numerical models have been developed to consider some aspects of groundwater dynamics such as the influence of seepage face and meniscuses formation, hysteresis effects, unsaturated flow dynamics, and porous media deformation. The laboratory data has then been used to verify numerical models and to examine their prediction capabilities.
New laboratory data from sand flume experiments for an idealized coastal aquifer forced by a simple harmonic forcing across a vertical boundary provided detailed measurements of the piezometric head very close to the interface. The data helped to consider the processes occurring near the boundary condition, particularly with respect to meniscus and seepage face formation during the falling tide. A numerical solution of the Richards’ equation was developed to model the influence of seepage face formation and meniscus suction and was evaluated against the data. The model-data comparisons
show good agreement with the pore pressure behavior high above the water table, but are sensitive to the choice of moisture retention parameters in the model.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text
10
O'Mara, Lauren. "Children of a sandy heart and other stories". Diss., Online access via UMI:, 2006.
Buscar texto completo
11
Zähringer, Sandy [Verfasser]. "Piezoelektrische Mikromembranaktoren mit einseitiger elektrischer Ansteuerung / Sandy Zähringer". München : Verlag Dr. Hut, 2017. http://d-nb.info/114957948X/34.
Texto completo
12
Tompkins, David Stuart. "Sandy tin tailings in Malaysia : characterization and rehabilitation". Thesis, University of Plymouth, 2003. http://hdl.handle.net/10026.1/2309.
Texto completoResumen
Cassiterite extraction in West Malaysia has left a legacy of some 80,000 hectares of nutrient-poor, drought-prone, quartz sandy tailings. Their proximity to urban centres has long made them a target for agricultural and forestry enterprises, and various techniques have been developed to overcome their intractability, including amendment with bulky organic matter and replacement with natural soils. Although reasonably successful, these approaches have often failed to acknowledge that a percentage of the original heavy mineral suite remains in sandy tailings, exerting possible phytotoxic effects and certainly raising concerns about the suitability of sandy tailings for agronomic crop production. To determine the nature and extent of trace element contamination of sandy tailings, ten different areas were identified and sampled in the states of Selangor and Perak. Preliminary analyses failed to corroborate earlier discoveries of elevated mercury and cadmium status, but lead, zinc, arsenic, uranium and rare earth elements were all common. However, greater concentrations of all these elements were found in clay (slime) tailings, which had been colonized by dense vegetation cover. This indicated that levels of trace elements in sandy tailings were not of themselves phytotoxic, but in the context of reduced nutrient availability, might exert a disproportionate influence on their colonization by plants. The colonization of sandy tailings by Melastoma malabathricum was therefore examined, revealing that in two of four sites, water contents were greater in colonized areas than the rest of each site. Macronutrient concentrations were also greater in colonized tailings, as were concentrations of zinc and manganese, but whether these were the cause or result of plant establishment could not be determined conclusively. Overall, trace element distribution in sandy tailings did not influence colonization by Melastoma, although in three of four populations, foliar concentrations of uranium were greater than those of a population growing on a natural soil. This has serious implications for the agronomic use of sandy tailings. The effects of bulky organic and clay amendment of sandy tailings on the availability and uptake of trace elements has never before been examined. A tropical greenhouse experiment was undertaken to examine the effects of peat and clay on the growth and trace element chemistry of Panicum miliaceum and Pueraria phaseoloides. The use of symbiotic mycorrhizal fungi was also included, since although these often improve the phosphorus nutrition of their hosts, they might also increase trace element uptake from pools sorbed by organic matter. Neither clay nor peat improved the growth of either plant species. However, addition of clay substantially increased the availability of aluminium and trace elements, and its use in rehabilitation attempts cannot be recommended. In contrast, peat reduced the availability of Co, Cu, As, La, Ce and U, whilst simultaneously improving the ECEC of sandy tailings. The effects of mycorrhizal inoculation were difficult to interpret, since the carrier medium used (predominantly zeolite) drastically altered the chemistry of soils to which it was added. Growth of Panicum and Pueraria was equally poor on two of three naturally sandy soils. Adding peat to sandy tailings produced plants with similar foliar chemistry to those grown on natural soils, suggesting that plant communities established on these natural siliceous media could act as models for the sustainable rehabilitation of anthropic mine tailings - something which has never before been suggested. A range of native species are recommended as having potential for further research into naturalistic rehabilitation.
13
Khachikian, Crist Simon. "Sorption of chlorinated solvents in a sandy aquifer". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40161.
Texto completoResumen
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1996.Includes bibliographical references (leaves 62-67).
by Crist Simon Khachikian.
M.Eng.
14
Manandhar, Rejina. "Return-Entry Risk Communication Following 2012 Hurricane Sandy". Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc848209/.
Texto completoResumen
Within risk communication, much is understood about pre-event warning related to evacuation and sheltering; however risk communication during the return-entry phase when ending evacuations has been largely under-studied in the disaster literature. Understanding of the return-entry risk communication process is important because returning early or prior to issuance of the all-clear message can make returnees susceptible to post-disaster risks, and also hamper post-disaster activities such as debris removal, traffic management, utility restoration and damage assessments. Guided by the Warning Components Framework and the Theory of Motivated Information Management, this dissertation focuses on risk communication as it pertains to organizational behavior during the return-entry process by examining how local emergency management organizations develop, disseminate and monitor return-entry messages. The data is collected through semi-structured telephone interviews with local emergency management organizations that managed return-entry following Hurricane Sandy. The findings of the study indicate that local emergency management organizations required information on post-disaster threats, damages, and utility and infrastructure condition in order to develop return-entry strategy for their community. Organizations improvised to their existing risk communication measures by adopting creative ways for information dissemination to the evacuees. They also utilized active and passive approach to monitor public response to the return-entry messages.
15
Toccalino, Patricia. "Optimization of hydrocarbon biodegradation in a sandy soil /". Full text open access at:, 1992. http://content.ohsu.edu/u?/etd,192.
Texto completo
16
Yargus, Michael W. "Experimental study of sound waves in sandy sediment /". Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/6075.
Texto completo
17
Nazhat, Yahya Nazar Yahya. "Behaviour of sandy soil subjected to dynamic loading". Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/9435.
Texto completoResumen
This thesis presents the kinematics occurring during lab-based dynamic compaction tests using high speed photography and image correlation techniques. High speed photography and X-ray microtomography have been used to analyse the behaviour of sandy soil subjected to dynamic impact. In particular, the densification mechanism of granular soils due to dynamic compaction is the main theme of the thesis. High speed photography and digital image correlation (DIC) techniques have enabled the deformation patterns, soil strains and strain localisations to be observed. Image correlation and X-ray scans revealed the formation, rate and growth of narrow tabular bands of intense deformation and significant volumetric change and provided answers towards a better understanding of the densification mechanism in dry granular soils due to dynamic compaction. As a quantitative tool, high speed photography has allowed the propagation of localised deformation and strain fields to be identified and has suggested that compaction shock bands control the kinematics of dynamic compaction. The displacement and strain results from high speed photography showed that soil deformation in the dynamic tests was dominated by a general bearing capacity mechanism similar to that widely stated in classic soil mechanics texts. Comparative static loading tests have been conducted to enable the dynamic effects to be clearly distinguished. This has enabled the densification process taking place below the soil surface to be investigated and identified. Simulations of the physical models were carried out using LS-DYNA finite element formulations for comparison and verification purposes. The FE simulations verified the general characteristics from the photography findings. However, simulation results were unable to predict the exact details of the strain localisation due to surface impacts during physical model tests.
18
Dortaj, Amal. "Permeability characteristics of fibre-reinforced Perth sandy soil". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2019. https://ro.ecu.edu.au/theses/2175.
Texto completoResumen
Fibres are mixed with soils to enhance their strength and hydraulic characteristics. Fibre-mixed soils are often known as the fibre-reinforced soils. In the past, both systematically and randomly reinforced soils have been used widely in civil and geotechnical structures. Randomly reinforced-soils using fibres exhibit advantages over systematically reinforced-soils because systematic reinforcements may result in weak planes within the soil mass. Randomly distributed reinforcements are also easier to apply and maintain for some applications.
Previous researchers have studied the strength, compaction and compressibility behaviour of fibre-reinforced soil. Study on characteristics of fibre-reinforced soils when saturated, however, is limited to piping resistance improvement. One of the main reasons for collapse of some of the hydraulic structures is soil piping that takes place on the downstream side as a result of upward seepage. Fibre-reinforced soils can be a solution in sustainable watershed management as they can be used in irrigation and drainage projects, such as river levees, contour bunds, temporary canal diversion works, temporary check dams, soil structures, stream restoration, etc., for seepage and permeability control.
This study focuses on permeability characteristics of fibre-reinforced soil. Permeability characteristics can vary depending on soil, fibre and methods used. Materials used in this study are Perth sandy soil, and locally available jute and waste tyre fibres. These materials were chosen because they are abundantly available in Perth area and surroundings. As for the waste tyre fibre, it was also chosen as a green approach to use waste materials in structures and solve their disposal problems. Fibre content varied from 0 to 10% with 1% intervals for tyre fibres and from 0 to 1.5% with 0.25% intervals for jute fibres. Fibre length varied from 5 to 25 mm with 5 mm intervals for jute fibres. Fibre length was constant in all experiments for tyre fibres as they come in a mixture of different lengths and studying the effect of length of permeability characteristics was not possible. Experimental tests were conducted on fibre-reinforced specimens in a constant-head permeameter. Experimental results suggest that the coefficient of permeability increases with an increase in fibre content for both fibre types (up to 100% for jute fibres and up to about 40% for tyre fibres). Also, it is observed that the coefficient of permeability increases with an increase in fibre length for jute fibres, as a general trend. As expected, water content increases and dry and saturated unit weights decrease with inclusion of higher fibre contents and longer fibres as a general trend.
Fibre-reinforced soil specimens and the water discharge were modelled numerically using the commercial software SEEP/W in order to study the effects of fibre inclusion on permeability characteristics. The findings from the developed numerical model agree well with the experimental observations.
19
Hajhashemi, Elham. "Agent-based Modeling for Recovery Planning after Hurricane Sandy". Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/85012.
Texto completoResumen
Hurricane Sandy hit New York City on October 29, 2012 and greatly disrupted transportation systems, power systems, work, and schools. This research used survey data from 397 respondents in the NYC Metropolitan Area to develop an agent-based model for capturing commuter behavior and adaptation after the disruption. Six different recovery scenarios were tested to find which systems are more critical to recover first to promote a faster return to productivity. Important factors in the restoration timelines depends on the normal commuting pattern of people in that area. In the NYC Metropolitan Area, transit is one of the common modes of transportation; therefore, it was found that the subway/rail system recovery is the top factor in returning to productivity. When the subway/rail system recovers earlier (with the associated power), more people are able to travel to work and be productive. The second important factor is school and daycare closure (with the associated power and water systems). Parents cannot travel unless they can find a caregiver for their children, even if the transportation system is functional. Therefore, policy makers should consider daycare and school condition as one of the important factors in recovery planning. The next most effective scenario is power restoration. Telework is a good substitute for the physical movement of people to work. By teleworking, people are productive while they skip using the disrupted transportation system. To telework, people need power and communication systems. Therefore, accelerating power restoration and encouraging companies to let their employees' telework can promote a faster return to productivity. Finally, the restoration of major crossings like bridges and tunnels is effective in the recovery process.Master of Science
20
Yani, Vuyolwethu Veronica. "Ecosystem health of the Nelson Mandela Bay sandy beaches". Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/1075.
Texto completoResumen
An investigation of ecosystem functioning of sandy beaches in the Nelson Mandela Bay Municipality (NMBM) was carried out with the aim of describing their type and pollution status. Water salinity, temperature, pH, beach slope, water inorganic nutrient concentrations, urea, and chlorophyll-a concentration as well as the composition of zooplankton, phytoplankton, meiofauna, benthic microalgae and bacteria were examined at thirteen beaches. The beaches were classified into three types: short beaches; long beaches with surf diatoms; and long beaches that import biomass (without surf diatoms). Of the thirteen beaches, five were non-polluted and eight polluted with polluting human activities in and around them. Most beaches were dominated by fine sand except for St. Georges Strand where the particles were medium to fine sand and Maitland’s River Beach, Bluewater Bay and Sardinia Bay that had coarse sand. Nutrient concentrations ranged from 1.98 ± 0.10 μM to 19.30 ± 3.02 μM nitrate; 4.88 ± 1.00 μM to 11.97 ± 1.00 μM ammonium; 0.67 ± 0.00 μM to 2.31 ±1.00 μM soluble reactive phosphorus; and 0.00 to 0.03 ± 0.00 μg l-1 urea-N. Chlorophyll-a concentrations ranged from 0.04 ± 0.02 to 1.57 ± 0.11 μg l-1. Chlorophyll-a concentrations were negatively correlated to ammonium for all beach types (short beaches: r = 0.94; long importing beaches: r = 0.95 and surf diatom beaches: 0.94) and to nitrate for short and long importing beaches (short: r = 0.97 and long importing: r = 0.85). By contrast, a positive correlation was found between observed between chlorophyll-a concentrations and urea for surf diatom beaches (r = 0.93) and for long importing beaches (r = 0.73). Chlorophyll-a concentrations were negatively correlated to short beaches (r = 0.99) and long importing beaches (r = 0.76). The E. coli and total coliforms in all the sampled beaches were within the recommended South African water quality guidelines for contact recreation as specified by DWAF (1995) except at New Brighton Beach (2 419 total coliforms/100 ml and 1 853 E. coli cells/100 ml) and St. Georges Strand (274 total coliforms/100 ml). Diatoms dominated the phytoplankton and benthic microflora; calanoid copepods dominated the zooplankton and deposit-feeding nematodes dominated the meiofauna in all the beaches with no changes found at polluted beaches.
21
Pörtner, Sandy [Verfasser]. "Charakterisierung der Proteinkinase pUS3 des Pseudorabis Virus / Sandy Pörtner". Greifswald : Universitätsbibliothek Greifswald, 2012. http://d-nb.info/1022772562/34.
Texto completo
22
Gianuca, N. M. "The ecology of a sandy beach in southern Brazil". Thesis, University of Southampton, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304348.
Texto completo
23
Mulvaney, Heidi Sarah. "An investigation into sandy beach stabilisation through controlled drainage". Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342713.
Texto completo
24
Jerolmack, Douglas J. "Modeling the dynamics and depositional patterns of sandy rivers". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37277.
Texto completoResumen
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2006.Includes bibliographical references.
This thesis seeks to advance our understanding of the dynamic nature, spatial organization and depositional record of topography in sand-bedded rivers. I examine patterns and processes over a wide range of scales, on Earth and Mars. At the smallest scale, ripples and dunes (bedforms) arise spontaneously under most natural flow conditions, acting as the primary agents of sediment transport and flow resistance in sandy rivers. I use physical modeling in a laboratory flume to explore the feedbacks among bedform geometry, fluid flow and sediment transport. Field observations of dunes in the North Loup River, Nebraska, show that bed roughness displays a statistical steady state and robust scaling. Motivated by these data, I develop a nonlinear stochastic surface evolution model for the topography of sandy rivers which captures the essence of bedform evolution in space and time. I then use a simplified kinematic model for bedform evolution to simulate the production of stratigraphy from migrating dunes, allowing a more accurate reconstruction of river flow conditions from preserved bedform remnants in rocks. At the channel scale I examine the conditions that lead to avulsion, the rapid abandonment of a river channel in favor of a new course at lower elevation.
(cont.) Simple scaling arguments and data from 30 natural systems reveal that anastomosing (multi-branch) rivers and distributary deltas are morphologies that arise when avulsion is the dominant mechanism of channel adjustment. I apply these arguments to the Niobrara River, Nebraska, which has experienced rapid in-channel deposition due to base level rise. I show that the planform pattern of the Niobrara is dominated by base-level-driven avulsions, and is decoupled from the smaller-scale sediment transport. At the largest considered scale are depositional fans, which are constructed by avulsing rivers. The evolution of a fan profile may be modeled at long time- and space-averaged scales as a diffusive process. I use such a model to invert topographic and volumetric data from a fluvial fan on Mars, producing an estimate of the time required to build the fan out of channel and overbank deposits.
by Douglas J. Jerolmack.
Ph.D.
25
Heyßel, Sandy [Verfasser]. "Psychische Störungen und Alexithymie in der Hautklinik / Sandy Heyßel". Greifswald : Universitätsbibliothek Greifswald, 2016. http://d-nb.info/1099440823/34.
Texto completo
26
Nel, Petronella. "Physical and biological factors structuring sandy beaches macrofauna communities". Doctoral thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/6146.
Texto completoResumen
Bibliography: leaves 188-199.Previous sandy beach research described beach macrofaunal communities according to the swash exclusion hypothesis (SEH). This hypothesis stated that more species are present on fine grained, flat dissipative beaches due to a more benign swash climate. It suggested that, as beach morphodynamics change to reflective conditions, which is experienced on coarse, steep beaches, few species can survive; these beaches are therefore characterised by lower macrofaunal diversities, abundance and biomass. Furthermore, little proof has been obtained of biological interactions such as competition or predation, and beaches have been described as physically controlled environments. The aim of this investigation was therefore to redifine the SEH in more specific terms, preferably into a form that is experimentally testable, and to find evidence of biological interactions that could be important enough to modify/explain population or community structures. Furthermore, the study aimed to find experimental procedures to serve as alternatives to the previously correlative type approach.
27
Hao, Hongtao. "Slumping of cultivated sandy soils : factors, processes and indicators". Thesis, Orléans, 2010. http://www.theses.fr/2010ORLE2061/document.
Texto completoResumen
Les sols sableux peuvent constituer une réserve potentielle de sols cultivables mais leur mise en valeur entraîne toujours des dégradations de la structure et une baisse du potentiel agricole. Une dégradation très fréquente est l’affaissement des couches labourées sous l’action de la pluie, ou slumping. Notre objectif était d’identifier les mécanismes et les facteurs déterminants du slumping afin de proposer des techniques de prévention. L’étude a été conduite sous pluies naturelles (au champ) et simulées (au laboratoire). Au champ, la cinétique d’évolution des caractéristiques hydriques et physiques du sol a été suivie après un labour à 20 ou à 40 cm de profondeur, dans un sol sableux tropical Thaïlande. Au laboratoire, un sol cultivé modèle a été élaboré dans un cylindre (h et Ø = 20 cm) à partir i) du sol prélevé dans le champ expérimental, ii) de la fraction sable (> 50 μm) extraite de ce même sol. Les sols modèles ont subi des pluies d’intensité variable (de 20 à 120 mm/h) après mise en place sur une table à succion (20 à 90 hPa). Le slumping se produit lorsque deux conditions sont réunies: (1) l’eau doit atteindre un potentiel proche de 0 hPa ce qui réduit la cohésion et aboutit à un équilibre fragile du sol comme décrit par la physique des milieux granulaires; (2) ce potentiel doit être maintenu assez longtemps pour qu’une instabilité se produise et entraine une brusque et importante diminution de la cohésion, donc l’effondrement du matériau. Si la fraction fine (<50 μm) est retirée du sol, aucun effondrement n’est observé, démontrant l’importance de cette fraction limonoargileuse, pourtant minoritaire (<10-15 % en masse), dans l’instabilisation et le slumping. La prévention du slumping et la gestion des sols sableux sont discutées en guise de conclusionThe sandy soil can serve as a potential reserve for cultivation. However, they are often considered as marginal because prone to have low productivity and problems of structure degradation. One of the degradations is compaction caused by rainfall or irrigation, which is called slumping. Our objective is to identify the processes and factors that affect slumping. The study had been done under natural conditions (field) and simulated conditions (laboratory) respectively. In the field, a tropical sandy soil in Thailand was selected. After 20 cm and 40 cm depth tillage, the dynamic of hydraulic and physical characteristics were measured. In laboratory, a cultivated soil model was build in a cylinder (height and diameter was 20 cm). We used two materials: 1) the original soil from the experiment field site, and 2) the sand fraction (> 50 μm) extracted from this soil. These model soils were submitted to rainfalls with different intensity (20 to 120 mm h-1), combined with different suction (20 to 90 hPa) on a suction table which can support the cylinder. The slumping for soil happens when two conditions were met: 1) the water potential reached a threshold value near 0 hPa. In this value, the soil cohesion decreased and a fragile equilibrium conditions were reached according to granular material theory; 2) the potential value was kept long enough and the cohesion continue decrease until they can no more support the equilibrium, so slumping happens. Surprisingly, in our treatment, when the fine particles (<50 μm) were taken out from the soil, no slumping was observed. This demonstrates the particles of clay and silt are very important to soil stability, even their content were very low as less than 10 percent. The possible ways to prevent slumping and management of sandy soils are also discussed
28
Coll, Florit Guillermo. "Ocean surface wave transformation over a sandy sea bed". Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep%5FColl.pdf.
Texto completoResumen
Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2009.Thesis Advisor(s): Herbers, Thomas H.C. "September 2009." Description based on title screen as viewed on November 5, 2009. Author(s) subject terms: Ocean waves, energy spectrum, SWAN, numerical prediction models, refraction. Includes bibliographical references (p. 57-59). Also available in print.
29
O'Toole, Peter. "The functionality of riparian zones in flat sandy catchments". Thesis, O'Toole, Peter (2014) The functionality of riparian zones in flat sandy catchments. PhD thesis, Murdoch University, 2014. https://researchrepository.murdoch.edu.au/id/eprint/26597/.
Texto completoResumen
Intermittent streams and flat sandy catchments are common throughout the world. In south Western Australia, Ellen Brook provides a model landscape for the study of water quality issues associated with managing flat sandy coastal catchments, where the highly permeable sands have limited capacity to intercept and store nutrients arising from agricultural activity. Revegetating riparian zones is universally used as a best-management practice to intercept nutrients and improve stream condition. However, the riparian zone can only be effective in nutrient removal if there is interaction between runoff and riparian vegetation. Key elements driving this interaction are slope, providing flow through the riparian zone and a mechanism for uptake and storage of nutrients (e.g. reactive soils). In addition, riparian vegetation is known to provide a suite of environmental benefits, however, there is little information on the influence of riparian vegetation on in-stream biota of intermittent streams.
The questions posed in this thesis are 1) can vegetated riparian zones effectively ameliorate nutrient inputs in flat sandy catchments (no slope and unreactive soils) and 2) do riparian zones on intermittent streams in flat sandy catchments influence in-stream biological communities?
This thesis compares hydrology and nutrient dynamics between an intermittent stream in a flat sandy landscape (Bingham Creek) and a perennial stream in a nearby landscape with slope and reactive soils (Lennard Brook). Nutrient stores within groundwater, soil and vegetation were analysed. A column experiment was undertaken to determine how the vertical rise and fall of groundwater affected nutrient dynamics in paddock and riparian soils and compared the effect of nutrient addition from fertiliser and cow manure. The thesis also examined the ecological condition of riparian vegetation and its influence on in-stream biota amongst a wider range of intermittent and perennial streams in this catchment.
In flat sandy catchments, the lack of slope and unreactive soils reduced the capacity for riparian vegetation to intercept and store nutrients. The dominant flow path was the vertical rise and fall of groundwater in response to rainfall, which limited the interaction of groundwater with the active root zone of riparian soils, reducing the potential for nutrient assimilation. However, slow (0.23-0.3 m/day) horizontal groundwater flow through riparian zone, results in extended residence times (106-141 days), allowed nutrient transformations to occur. Riparian and paddock soils at Bingham Creek had a poor nutrient holding capacity, resulting in nutrients being stored in the groundwater (e.g. filterable reactive phosphorus (FRP) 48-600 μg/L-1) and not the soil (e.g. 4-510 mg.P/kg). Whereas at Lennard Brook the improved soil characteristics (increased iron oxides and clay) provided a greater opportunity for nutrient interception and storage by the soils (e.g. 29-1037 mg.P/kg) and groundwater flow to the stream was low in phosphate (e.g. FRP 10-74 μg/L-1).
The riparian vegetation had a similar community structure at both sites and contributed comparable amounts of litterfall (369 and 404 g/m2) and nutrients per unit area (0.8-1.5 and 0.5-1 mg.P/m2) at Bingham Creek and Lennard Brook, respectively. This enhanced the organic matter content of underlying riparian soils that in turn slowed the rate of water movement (paddock 0.08-0.7 L/hr, riparian 0.04-0.24 L/hr), improved the phosphorus binding capacity of the soil and promoted loss of mineral nitrogen, probably by denitrification. However, the increased carbon content also supported a greater microbial community and the input of extra nutrients (including labile carbon) increased microbial respiration, leading to release of iron-bound phosphorus into groundwater.
In the Ellen Brook catchment, flow regime (Global R = 0.444, P < 0.001) and the presence/absence of riparian vegetation (Global R = 0.407, P < 0.001) were the most influential factors associated with invertebrate assemblage composition. On average there were more invertebrate families in vegetated (30 ± 1.4) streams than unvegetated (27 ± 3.2) streams. Riparian vegetation helped shape and improve in-stream biological communities through the provision of organic matter for food and habitat and by limiting algal growth in stream water through shading. This was illustrated by a higher proportion of algal grazers (Chironominae and Physidae) in unvegetated streams and more detrital feeders (Leptoceridae, Gripopterygidae, Ceinidae) in vegetated streams.
A conceptual model of hydrology and nutrient dynamics for riparian zones in flat sandy catchments was developed, which describes the key points of difference to the hydrological and nutrient dynamics in sloped catchments with reactive soils. Riparian vegetation appears to be acting similarly between catchment types but the capacity for riparian zones to remove nutrients in flat sandy catchments is limited due to soil type and hydrology. However, in these catchments, riparian zones are also the only sink contributing to a reduction in nutrient export from the catchment and so still have value in regulating nutrient dynamics. Clearly, riparian vegetation alone across the catchment alone cannot stem the flow of nutrients in flat sandy catchments. Instead, a multi-pronged approach is required to reduce nutrient export and improve the nutrient holding capacity of soils. Furthermore, riparian vegetation helps maintain and improve in-stream biological communities in intermittent and perennial streams in sandy catchments with low relief. Overall, riparian vegetation increased the retention of nutrients, improved soils and in-stream biodiversity, warranting the protection and rehabilitation of riparian zones in flat sandy catchments.
30
Ching, Peter. "Creep in sands a study of time dependent deformation of reclamation sand fill under constant effective stress /". Click to view the E-thesis via HKUTO, 2001. http://sunzi.lib.hku.hk/hkuto/record/B43894598.
Texto completo
31
Ching, Peter y 秦培德. "Creep in sands: a study of time dependent deformation of reclamation sand fill under constant effectivestress". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B43894598.
Texto completo
32
Weerts, Albrecht Henricus. "Transport properties of unsaturated sandy soils analogies, measurements and models /". [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/32941.
Texto completo
33
Kunzen, Thomas. "HYDROLOGIC MASS BALANCE OF PERVIOUS CONCRETE PAVEMENT WITH SANDY SOILS". Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3249.
Texto completoResumen
Use of pervious concrete pavement as a method of stormwater management has shown great promise in previous studies. Reduction in runoff, water quality improvements, and long-term economic benefits are but a few of its many advantages. Regulatory agencies such as the St. Johns River Water Management District require further research into the performance of pervious concrete pavement before granting credits for its use as a best management practice in controlling stormwater. As a part of a larger series of studies by UCF's Stormwater Management Academy, this thesis studies the hydrologic mass balance of pervious concrete pavement in sandy soil common in Florida. In order to conduct this study, a field experiment was constructed at the UCF Stormwater Field Lab. The experiment consisted of three 4-foot tall cylindrical polyethylene tanks with 30-inch diameters. All three tanks were placed into the side of a small embankment and fitted with outlet piping and piezometers. The test tanks were assembled by laying a 6-inch layer of gravel into the bottom of each tank, followed by a layer of Mirafi geofabric, followed by several feet of fine sand into which soil moisture probes were laid at varying depths. Two of the tanks were surfaced with 6-inch layers of portland cement pervious concrete, while the third tank was left with a bare sand surface. Mass balance was calculated by measuring moisture influx and storage in the soil mass. Data collection was divided into three phases. The first phase ran from August to November 2005. Moisture input consisted of normal outdoor rainfall that was measured by a nearby rain gauge, and storage was calculated by dividing the soil mass into zones governed by soil moisture probes. The second phase ran for two weeks in March 2006. Moisture input consisted of water manually poured onto the top of each tank in controlled volumes, and storage was calculated by using probe readings to create regression trendlines for soil moisture profiles. The third phase followed the procedure identical to the second phase and was conducted in the middle of April 2006. Data tabulation in this study faced several challenges, such as nonfunctional periods of time or complete malfunction of essential measuring equipment, flaws in the method of calculating storage in phase one of the experiment, and want of more data points to construct regression trendlines for soil moisture calculation in phases two and three of the experiment. However, the data in all phases of the experiment show that evaporation volume of the tanks with pervious concrete surfacing was nearly twice that of the tank with no concrete. Subsequent infiltration experiments showed that pervious concrete pavement is capable of retaining a portion of precipitation volume, reducing infiltration into the underlying soil and increasing total evaporation in the system.M.S.C.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering
34
Frost, Matthew. "Large-Scale spatial patterns of sandy beach macrofauna community composition". Thesis, University of Plymouth, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289587.
Texto completo
35
Jalali, Mohsen. "Measuring and modelling the leaching of potassium in sandy soil". Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360760.
Texto completo
36
Walker, D. J. "Nearshore hydrodynamics and the behaviour of groynes on sandy beaches". Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46871.
Texto completo
37
Hallmann, Sandy [Verfasser]. "Rolle des Chemerin-Chemerinrezeptorsystems in Glukosehomöostase und Neoplasie / Sandy Hallmann". Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1109790414/34.
Texto completo
38
Eid, Naglaa Mahmoud. "Electro-kinetic concentration and retention of nitrate in sandy soil". Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187265.
Texto completoResumen
Laboratory experiments utilizing closed and open system experiments were conducted in this study to evaluate the applicability of using an electro-kinetic process to concentrate and retain nitrate close to the anode. A finite difference model was developed to predict the pH gradient developed during the electro-kinetic process. Model results then were used with a derived regression equation between pH and N0₃- to predict the nitrate gradient developed during an electro-kinetic process. The results of this research revealed that an electro-kinetic method is an effective means for concentrating and retaining nitrate close to the anode in saturated sandy soil even under a strong hydraulic gradient. Results also support the validity of using a finite difference and regression equation model to predict the spatial and temporal distribution of N0₃- developed under an electro- kinetic process for both closed and open system configurations.
39
Onur, Emine Mercan. "PREDICTING THE PERMEABILITY OF SANDY SOILS FROM GRAIN SIZE DISTRIBUTIONS". Kent State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1389550812.
Texto completo
40
Rice, Lindsay L. "An Analysis of Public Perception and Response to Hurricane Sandy". Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5114.
Texto completoResumen
Hurricane Sandy made landfall in Brigantine, New Jersey on October 29th, 2012. The storm impacted the coastal regions of New Jersey and New York, especially the heavily populated area of New York City. This research, which analyzes secondary data obtained from a telephone survey, investigates the public response of residents before, during and after Hurricane Sandy. The survey consisted of questions regarding what the residents expected concerning the threat of Hurricane Sandy, whether it matched what they experienced, where they got their information and how they made their decision to evacuate or not. The results from the survey were statistically analyzed in order to answer important research questions about public perception of Sandy's impacts. A Vulnerability Assessment of New York City, where some of Sandy's impacts were felt the most, was completed in order to understand why this area was so vulnerable. The concern level of various hurricane related hazards was analyzed and correlated to demographic variables to determine a relationship among the variables. A qualitative analysis was performed on the survey questions "Why did you evacuate?" and "Why did you not evacuate?" in order to determine themes in relation to people's reasons for evacuating or not evacuating. Finally, differences in how the public perceived Hurricane Sandy before and after the storm were analyzed and may be used for improving communication of the forecast to the public. Interdisciplinary research in this area is needed in order to better understand the public's need for appropriate warnings to ensure safety. Results show that residents were most concerned about wind damage and that they mainly used their television to obtain their information about the storm. Also, the most common reasons respondents reported for evacuating were because of the threat of possible impacts (storm surge, flooding, wind, rain and waves), the forecast called for bad conditions, or being told, recommended or convinced to leave. The main reasons reported by respondents for not evacuating are thinking that the impacts would not be bad in their area, feeling prepared or safe and thinking they could handle the impacts. This research can be used in the future for improving hurricane warning communication to the public.
41
Pandey, Lopa Mudra. "Electrical resistivity of sandy soil with water, leachates and seawater". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2015. https://ro.ecu.edu.au/theses/1724.
Texto completoResumen
Liners are used in the engineered containment systems such as landfills for controlling the migration of contaminants. Although there are several techniques for detecting the leakages through the liners, use of the electrical resistivity method can assist in timely detection of contaminant migration in cost-effective manner. This method is based on the well-established fact that the electrical resistivity of soils and other geomaterials is much higher than the electrical resistivity of water, leachates or any liquid effluents which may permeate the landfill foundation material. Additionally, the geotechnical properties of a soil exhibit a close relationship with its electrical resistivity values for different conditions.
This thesis presents the results of investigation into the interaction between the various electrical factors pertaining to resistivity tests in Perth sandy soil (specifically AC-input voltage and frequency) and those controlling the soil characteristics, specifically water/fluid content and relative density of the soil, and the types of permeant employed in the tests, namely distilled water, tap water, three leachates and seawater. For a landfill system situated near a salt water body, the effects of seawater and seawater-leachate intrusion have also been scrutinized. For the measurement of electrical resistivity for different soil density and contamination conditions, the experimental apparatus was developed as per Australian standard AS 1289.4.4.1-1997 as a significant part of the thesis work.
The test results indicate that the resistivity of the sandy soil is almost independent of both AC-input voltage and frequency within the ranges used, while the choice of electrode material has an insignificant effect on the outcome of tests using this method. It is observed that the resistivity of sandy soil decreases rapidly with an increase in water/fluid content, but the rate of decrease reduces considerably for water contents over 12% in the case of distilled water and 10% for tap water, irrespective of the relative density. The resistivity is found to decrease almost linearly with an increase in relative density. However, the effect of relative density on the electrical resistivity of the soil is found to be negligible at higher water contents.
In the landfills and similar containment systems, there is a possibility of leakage of leachate across the liners and/or seawater intrusion, depending on the location of the landfills. Hence, the study was conducted to evaluate the effects of contamination on the electrical resistivity of the Perth soil by changing the fluid content with various combinations of tap water, three different leachates and seawater. The study shows that for any mix of leachate and tap water, the resistivity decreases rapidly with increasing fluid content; however, the rate of decrease reduces significantly for fluid contents over 9%, irrespective of the type of leachate. Almost the same trend is observed for the case of seawater.
Correlations between electrical resistivity, water content, relative density, amount and the composition of permeating fluid, which are applicable to the soil and permeating fluids used in the study, have also been developed and presented.
42
Costa, Fernanda Reinert Thome. "On the Bromeliaceae of the restinga of Barra de Marica in Brazil : environmental influences on the expression of crassulacean acid metabolism". Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261237.
Texto completo
43
Keith, Mackenzie Karli. "Reservoir Evolution Following the Removal of Marmot Dam on the Sandy River, Oregon". PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/532.
Texto completoResumen
The October 2007 removal of Marmot Dam, a 14.3-m-tall dam on the Sandy River in northwestern Oregon storing approximately 730,000 m3 of impounded sediment, provided an opportunity to study short- and long-term geomorphic effects of dam removal. Monitoring reservoir morphology during the two years following dam decommissioning yields a timeline of reservoir channel change. Comparison of a pre-dam survey in 1911 with post-removal surveys provides a basis from which to gage the Reservoir Reach evolution in the context of pre-dam conditions. Analyses of time-lapse photography, topographic surveys, and repeat LiDAR data sets provide detailed spatial and temporal documentation of a release of sediment from the reservoir following dam removal. The majority of morphologic changes to the reservoir largely took place during the first few days and weeks following removal. Channel incision and widening, along with gradient changes through the Reservoir Reach, exhibit diminishing changes with time. Channel incision rates of up to 13 m/hr and widening rates of up to 26 m/hr occurred within the first 24 hours following breaching of the coffer dam. Although channel position through the Reservoir Reach has remained relatively stable due to valley confinement, its width increased substantially. The channel reached an average width of 45 m within two weeks of breaching, but then erosion rates slowed and the channel width reached about 70 to 80 m after one and two years, respectively. Diminishing volumes of evacuated sediment were measured over time through quantitative analysis of survey datasets. About 15 percent of the initial impounded sediment was eroded from the Reservoir Reach within 60 hours of breaching; after one and two years, 50 and 58 percent was eroded, respectively. Grain-size analysis of terraces cut into reservoir fill following dam removal show that bed material coarsened over time at fixed elevations and vertically downward as the channel incised. Overall, these findings indicate valley morphology and local in-channel bedrock topography controlled the spatial distribution of sediment within the reservoir reach while variability in river discharge determined the timing of episodic sediment release. Changes within the Reservoir Reach shortly after dam removal and subsequent evolution over the two years following removal are likely attributable to 1) the timing and intensity of flow events, 2) the longitudinal and stratigraphic spatial variations in deposit grain-size distributions initially and over time, and 3) the pre-dam topography and existing valley morphology.
44
Rees, Sean David. "Effects of Fines on the Undrained Behaviour of Christchurch Sandy Soils". Thesis, University of Canterbury. Civil and Natural Resources, 2010. http://hdl.handle.net/10092/3940.
Texto completoResumen
Liquefaction of sandy soil has been observed to cause significant damage to infrastructure during major earthquakes. Historical cases of liquefaction have typically occurred in sands containing some portion of fines particles, which are defined as 75μm or smaller in diameter. The effects of fines on the undrained behaviour of sand are not however fully understood, and this study therefore attempts to quantify these effects through the undrained testing of sand mixed with non-plastic fines sourced from Christchurch, New Zealand.
The experimental program carried out during this study consisted of undrained monotonic and cyclic triaxial tests performed on three different mixtures of sand and fines: the Fitzgerald Bridge mixture (FBM), and two Pinnacles Sand mixtures (PSM1 and PSM2). The fines content of each host sand was systematically varied up to a maximum of 30%, with all test specimens being reconstituted using moist tamping deposition.
The undrained test results from the FBM soils were interpreted using a range of different measures of initial state. When using void ratio and relative density, the addition of fines to the FBM sand caused more contractive behaviour for both monotonic and cyclic loadings. This resulted in lower strengths at the steady state of deformation, and lower liquefaction resistances. When the intergranular void ratio was used for the interpretation, the effect of additional fines was to cause less contractive response in the sand. The state parameter and state index were also used to interpret the undrained cyclic test results – these measures suggested that additional fines caused less contractive sand behaviour, the opposite to that observed when using the void ratio. This highlighted the dependency on the parameter chosen as a basis for the response comparison when determining the effects of fines, and pointed out a need to identify a measure that normalizes such effects.
Based on the FBM undrained test results and interpretations, the equivalent granular void ratio, e*, was identified from the literature as a measure of initial state that normalizes the effects of fines on the undrained behaviour of sand up to a fines content of 30%. This is done through a parameter within the e* definition termed the fines influence factor, b, which quantifies the effects of fines from a value of zero (no effect) to one (same effect as sand particles). The value of b was also determined to be different when interpreting the steady state lines (bSSL) and cyclic resistance curves (bCR) respectively for a given mixture of sand and fines.
The steady state lines and cyclic resistance curves of the FBM soils and a number of other sand-fines mixtures sourced from the literature were subsequently interpreted using the equivalent granular void ratio concept, with bSSL and bCR values being back-calculated from the respective test data sets. Based on these interpretations, it was concluded that e* was conceptually a useful parameter for characterizing and quantifying the effects of fines on the undrained behaviour of sand, assuming the fines influence factor value could be derived.
To allow prediction of the fines influence factor values, bSSL and bCR were correlated with material and depositional properties of the presented sand-fines mixtures. It was found that as the size of the fines particles relative to the sand particles became smaller, the values of bSSL and bCR reduced, indicating lower effect of fines. The same trend was also observed as the angularity of the sand particles increased. The depositional method was found to influence the value of bCR, due to the sensitivity of cyclic loading to initial soil fabric. This led to bSSL being used as a reference for the effect of fines, with specimens prepared by moist tamping having bCR > bSSL, and specimens prepared by slurry deposition having bCR < bSSL.
Finally the correlations of the fines influence factor values with material and depositional properties were used to define the simplified estimation method – a procedure capable of predicting the approximate steady state lines and cyclic resistance curves of a sand as the non-plastic fines content is increased up to 30%. The method was critically reviewed based on the undrained test results of the PSM1 and PSM2 soils. This review suggested the method could accurately predict undrained response curves as the fines content was raised, based on the PSM1 test results. It also however identified some key issues with the method, such as the inability to accurately predict the responses of highly non-uniform soils, a lack of consideration for the entire particle size distribution of a soil, and the fact the errors in the prediction of bSSL carry through into the prediction of bCR. Lastly some areas of further investigation relating to the method were highlighted, including the need to verify the method through testing of sandy soils sourced from outside the Christchurch area, and the need to correlate the value of bCR with additional soil fabrics / depositional methods.
45
Shariat, Sara. "The spatio-temporal properties of Twitter users during the Sandy Hurricane". Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-252092.
Texto completoResumen
The wide-scale deployment of networked communication and sensing devices, e.g. phones and tablets, provides a previously unimaginable amount of information about people's environment and movements. These devices often have access to high accuracy localization technology, such as GPS and Wi-Fi/cell tower localization. Users of these devices also frequently participate in global social networks, for instance Twitter, Facebook and Google+. The information obtained from social media in a catastrophic event is unique and cannot be found anywhere else in the information space, they may even have the geographical knowledge of the influenced areas, which can be high importance for those outside of the area. This role is highlighted in the occurrence of hurricane sandy on 2012. Geo- tagged social media messages expose user’s locations and subsequent movements, providing near-instantaneous data about how people are responding to a disaster event. The need for up-to- date information is paramount for the authorities so they can organize the most efficacious response. They need to know what issues are affecting people on the ground, where people are located and whether they can/will evacuate. This project will analyze gigabytes of data collected during the Sandy Hurricane of 2012 on the American East Coast. Millions of geo-tagged tweets from hundreds of thousands of users were collected and offer a unique insight into how Twitter activity increased during the hurricane in the area of the event and the movement pattern of the people changed during the hurricane. These reactions and movements of people during the Hurricane Sandy help the process of evaluation so responders can have a more robust situational awareness of the disaster.
46
Boet-Whitaker, Sonja K. (Sonja Kathleen). "Buyouts as resiliency planning in New York City after Hurricane Sandy". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111375.
Texto completoResumen
Thesis: M.C.P., Massachusetts Institute of Technology, Department of Urban Studies and Planning, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 68-74).
Land buyout programs may be used to significantly improve climate resilience by creating a protective ecological buffer area to protect land at high risk of flooding. This thesis assesses the success of the New York State land buyout on the East Shore of Staten Island in achieving this resilient outcome. The New York State buyout program was created after Hurricane Sandy in October 2012 in response to pressure from landowners who had been flooded in the storm. New York City declined to participate in a buyout in response to Sandy but offered to acquire storm-damaged homes in other areas where the New York State buyout was not offered. Through the New York City program, acquired properties would be resold to private entities at auction. In contrast, the New York State program, which purchased 37 acres of land within the 100-year floodplain, was legally bound to hold the properties bought through their program as open space in perpetuity. The state was able to promise former residents that their land would become a buffer for inland areas, increasing resilience along this vulnerable coastline. I analyze the success of the state program in achieving this goal by assessing participation and attrition rates within designated buyout areas, as well as reasons for attrition. I find that the lack of coordinated goals and agreed-upon tools prevented New York Rising from successfully achieving the highest measure of resilience: creating a coastal buffer area to protect residents from sea level rise and future flooding.
by Sonja K. Boet-Whitaker.
M.C.P.
47
Harvey, Dennis C. (Dennis Cameron). "After retreat : buyout programs and local planning goals after Hurricane Sandy". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/111383.
Texto completoResumen
Thesis: M.C.P., Massachusetts Institute of Technology, Department of Urban Studies and Planning, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 75-82).
State run home buyout programs are becoming increasingly popular as a means to mitigate flood damage to homes within floodplains. However, there are many local benefits associated with buyout programs, including the removal of services from the neighborhood, increased flood protection for adjacent neighborhoods, and increased green space for conservation and recreation purposes. With limited federal funding for these programs, policy designers make an effort to maximize these benefits. This thesis uses structured interviews, descriptive statistics, and mapping, to compare New Jersey's Blue Acres buyout program and the New York Rising Buyout and Acquisition Program. First, it compares the programs through the lens of 8 key policy decisions including parent institution, funding sources, municipal relationship, site selection, outreach, the offer, continued land management and future plans. Then, it uses a common framework to compare 3 coastal municipalities that utilized buyout programs, including Woodbridge, NJ, Lindenhurst, NY, and Mastic Beach, NY. I found that the ability to achieve local planning goals was influenced primary by the program's community outreach approach, site selection process, and its relationship with the municipality. As states design the next generation of buyout programs to deal with the increased flood risks associated with climate change, this paper will help guide buyout policy to achieve better outcomes.
by Dennis C. Harvey.
M.C.P.
48
Tsai, Shing-De y 蔡聖德. "Distinguish from Saturated Sand and Sandy-Gravel Layers Using Seismic Exploration". Thesis, 1996. http://ndltd.ncl.edu.tw/handle/75149399246991086157.
Texto completoResumen
碩士國立中興大學
土木工程學系
84
Development of the shallow-groundwater resources is considered to solve the problems of water resources for industrial and residential usage. Obviously, topography and geology have a lot of influence of forming of the shallow-groundwater system, which can be studied by coordinating the "boring log" and the "geophysical exploration" methods. Riverbed in Hsilo section of Cho-Shu river is composed of sands and sandy-gravels. Shallow- groundwater is usually exists beneath riverbed. Sandy-gravel layer with better permeability can be used as water collection system; however, electrical prospecting method cannot tell the small difference of apparent resistivity between sands and sandy-gravel layers. Therefore, the research tries to coordinate the seismic refraction method and the shallow seismic reflection method to judge the sandy- gravel layer location. In order to get better ordinary records, we had collected some data before the real research began. First, we collected related hydrogeologic information. Second, we investigated the site field in order to decide proper measuring area. Third, we estimated field structures by researching shallow field materials and by studying boring logs'' information nearby. Forth, we did noise test and decided the operation parameter and work time. After collecting all information, we organized data and made detailed analy sis to get helpful results. Coordinating the results of seismic reflection and shallow seismic reflection can not only map the interface between sand layer and sandy-gravel layer beneath the groundwater, but also draw a picture of existing water layer structure in the measured area. After discussing all related data, we think the shallow-groundwater the measured area streams toward river course from east to west beneath the loosen covering clay. Finally, we think that the way that coordinates the seismic reflection method and shallow seismic reflection method is a good technique to investigate water resources deplacement systems.
49
Chen, Peng-Jung y 陳芃蓉. "Study of Bacteriophages Transportin Sandy Soil". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/b5mxz8.
Texto completoResumen
碩士逢甲大學
環境工程與科學所
90
Abstract An event of foot and mouth disease communicated by the pigs broke out in Taiwan in 1997 and the infected pigs were landfill disposed. The object of this research was to study the movement of the virus of the foot and mouth disease in the soil. A glass column filled with ottawa sand was set up and groundwater was used as leaching water in the study. Due to the difficulty of detecting the pathogenic virus causing foot and mouth disease, bacteriophages were replaced as substitutes. The single agar layer containing 2,3,5-triphenyl tetrazolium chloride (TPTZ) was utilized for the plague assay. The bacteriophages used in the experiment were phage G, isolated from the Faze River, and the male specific model virus (MS2). The adsorption between the bacteriophages and the ottawa sand as well as the inactivation rate of the bacteriophages in groundwater could be revealed through the batch experiment. The adsorption of phage G in ottawa sand fitted the Langmuir isotherm, while that of MS2 belonged to the Freundlich isotherm. An equilibrium for the adsorption of MS2 and phage G in the ottawa sand could be reached after 45 minutes and 60 minutes with an adsorption rate of 82 % and 75 % respectively. During the period of 120 minutes, the inactivation rate of phage G and MS2 was both zero. When phage G and MS2 were in the groundwater simultaneously, there was no adsorption competition between phage G and MS2. The column experiment was processed by observing how reuse of ottawa sand affects the adsorption of bacteriophages. When a 20-cm high sandy column was used, the outflow rates of phage G in the new and reused ottawa sand were 7.0 % and 3.5 % respectively. Therefore, the reuse of ottawa sand reduced the adsorption rate of bacteriophages. When the flow velocity of leaching water was 1.74 ml/min, the maximum outflow rates of phage G and MS2 were 0.52 % and 0.03 % within 10 minutes. When the flow velocity of leaching water was lower (1 ml/min), the maximum outflow rates of phage G and MS2 were 0.15 % and 0.01 % respectively. It showed the flow velocity of leaching water was the main factor that affected the breakthrough of bacteriophages in the sandy column. The maximum outflow rates of phage G in a saturated column and an unsaturated column were 0.32 % and 0.46 % respectively. For MS2, they were 0.013 % and 0.014 %, which indicated that MS2 had a stronger adsorption level in the unsaturated column and in the ottawa sand. When the electrical conductivity of the leaching water decreased from 345 - 351 μs/cm to 16 - 25 μs/cm, the total outflow rate of phage G increased from 1.85 % to 25.41 % and that of MS2 increased from 0.69 % to 8.53 %. This demonstrated that the decrease of electrical conductivity attenuated the adsorption of bacteriophages in the sandy column.
50
ZHU, WEN-ZHOU y 朱文周. "Resilient modulus of saturated sandy subgrade". Thesis, 1992. http://ndltd.ncl.edu.tw/handle/91537643176111812204.
Texto completo