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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
611

COMPOST BEDDED PACK BARNS FOR DAIRY CATTLE: BEDDING PERFORMANCE AND MASTITIS AS COMPARED TO SAND FREESTALLS

Eckelkamp, Elizabeth A 01 January 2014 (has links)
Lameness and mastitis are the two most costly diseases in the dairy industry. Reduction of these diseases through housing and management is beneficial. Compost bedded pack (CBP) and sand freestall barns were compared in a long-term, on-farm study to assess the effect of housing on each disease. Another research objective was to evaluate the effects of ambient weather conditions on moisture and 20 cm internal temperature of CBP. Compost bedded pack moisture, C:N ratio, and internal temperature effects on cleanliness, mastitis, and bedding bacterial counts were also considered. The last research objective was to evaluate the economics of bedding material decisions in CBP and provide a user-friendly decision support tool to predict bedding costs and usefulness.
612

Undersökning av miljöpåverkan från järnsand i en sedimentstudie i Inre-viken, Skellefteå / Using sedimentary records to investigate iron sand’s environmental impact in Inre-viken, Skellefteå (English)

Rikard, Haldebo January 2015 (has links)
With rapidly urbanizing societies, waste management needs attention. In 2008, EUs Waste Framework Directive (WFD) set new concepts, like reducing usage of natural materials. Thus, the interest for alternative materials increased. In Skellefteå, since the 1970’s, iron sand has often substituted natural gravel in road construction. But, today stricter regulations might forbid iron sand for further use. The issue is whether leachate from iron sand causes heavy metal pollution or not. This thesis tried to provide more knowledge into iron sand’s environmental impact. In order to investigate this, a sediment sample (<53 cm deep) collected in Inre-viken, a lake 50m from a road with iron sand, were analyzed for Zn, Pb and Cu concentrations. Enrichment factor (EF), national benchmarks, and reference data were used to evaluate anthropogenic impact and age-determine the sediment. The results showed: (1) Inre-viken has elevated heavy metal levels compared to pre-industrial levels, with highest Cu (133 mg/kg) and Zn(204 mg/kg) concentrations found in the surface layer. (2) Zn and Cu showed an increase between 41-0 cm depth (1970-2015), but only Cu reaches high concentrations, while Zn and Pb range between low to very low concentrations. (3) The metal enrichment is low compared to the reference lake. The findings show that there are elevated levels in Inre-viken compared to pre-industrial levels. However, identifying the main source of pollution is difficult, because many pollution sources exist in the area. To determine if iron sand is the culprit, further studies are necessary.
613

Reclaiming an Indiana sand, gravel and limestone quarry for residential use

Papadinoff, Thomas P. January 1985 (has links)
The purpose of this creative project was to derive and communicate the design process for the reclamation of an active quarry site to a residential community. An examination of existing land reclamation and housing design knowledge was conducted to form the basis for original design theories. The communication and presentation of study recommendations was applied to a case study site: an active sand, gravel, and limestone quarry located near Muncie, Indiana. A methodology was developed to analyze the site for its mining, housing and visual potential. Environmentally responsive strategies to determine rural community structure, lake form design, and housing character were developed. An integration of analyses and design strategies yielded the final land use concept and the associated site development concept. The final product of the study was a reclamation concept plan directing mineral extraction and reclamation efforts toward optimal mining and housing potential. It was the intention of this study to discuss and present its design theories, recommendations, and process in map form capable of explaining the study in its entirety without additional verbal or written communication. / Department of Landscape Architecture
614

Relationship between 20th century dune migration and wetland formation at Cape Cod National Seashore, Massachusetts / Relationship between twentieth century dune migration and wetland formation at Cape Cod National Seashore, Massachusetts

Sagintayev, Zhanay January 2006 (has links)
Outer Cape Cod (Massachusetts) is dominated by active and stabilizing parabolic and transverse dunes interspersed with numerous inter-dune wetlands. Dune migration has been significantly affected by human activities; conversely, current dune movements are affecting local populations. The objective of the reported research was to assess, using remote sensing and geographic information systems (GIS) technologies, migration of the Cape Cod dunes and the effect of dune movement on distribution of associated wetlands. Aerial photographs from 1938 through 2003 were analyzed to track individual dune movements and subsequent wetland propagation and expansion. Absolute dune movement rates during this period were computed, with a plot of dune movement as a cumulative function. One sub-problem of this study was to quantify `white' areas of active moving sand and `dark' areas of vegetation, in order to quantify changes in vegetative cover with wetland propagation and, conversely, vegetative disappearance with dune movement. Attempts were made to correlate the Palmer Drought Severity Index (PDSI) with dune migration. Based on review of aerial photographs, parabolic dunes have migrated 150 to 250 m since 1938, with 60% of the movement occurring between 1938 and 1977. The relation between absolute parabolic dune migration and corresponding PDSI is approximately logarithmic. Maximum dune migration is associated with PDSI values lower than -2 and reflects moderate drought conditions. Wetlands consistently trailed the dunes, and the distance of wetland movement was related to dune movement distances. Wetland migration was particularly marked from the 1950s to the 1980s. Based on review of georeferenced aerial photographs, it is concluded that marked stabilization of Cape Cod dunes occurred in the 1980s and 1990s, with renewed movement in the 21st Century. This study provides a practical application for assessment of dune migration and vegetative transformations over time using remote sensing and GIS technologies. / Department of Natural Resources and Environmental Management
615

Ceninetel a,it e tte tenew = 'Helping each other take care of the land' : an ethnoecological approach to restoring the coastal dune ecosystem of Tixen and Island View Beach / Helping each other take care of the land

Bartley, Raymond Glenn 26 October 2009 (has links)
This study focuses on the ecological restoration of a coastal dune ecosystem on the east coast of Vancouver Island that supports bird migration. The area is also a part of the traditional homelands of the Tsawout First Nation. Because environmental degradation has impaired the functioning of both ecological and cultural systems, the restoration of this ecosystem requires a distinctive approach. An “ethnoecological” approach to restoration is presented that seeks collaboration between ecological science and traditional ecological knowledge in order to restore the ecological integrity and human connection to this culturally significant landscape. Guided by the values of the Tsawout community, and the practice of good ecological restoration, I make recommendations for short and long term restoration actions. A set of ethnoecological restoration guidelines are presented to help guide future projects with the dual mandate of ecology and culture. Finally, opportunities for making connections between this project and other regional initiatives are explored in an attempt to restore links in the migratory habitat chain.
616

Development of the cone pressuremeter

Nutt, Nigel Robert Forbes January 1993 (has links)
The cone pressuremeter is an in situ testing device comprising a pressuremeter mounted behind a cone penetrometer of the same diameter. Previously reported tests had indicated that the cone pressuremeter can provide measurements of soil strength, stiffness and in situ stress. The study presented in this thesis is aimed at developing methods of interpretation of the cone pressuremeter that can be applied with confidence to a variety of soil types. Carbonate sands have been the cause of significant problems associated with the design of foundations for offshore structures. A programme of cone pressuremeter testing in a carbonate sand from the west coast of Ireland is presented. Tests were carried out in a calibration chamber where conditions of vertical and horizontal stress and relative density were controlled. The influence of these parameters on measured values of cone resistance and pressuremeter limit pressure is assessed. Similar tests were also carried out in a felspathic sand, and correlations have been presented for deriving horizontal stress and relative density that are applicable to most types of sand. The influence of creep strains and of overconsolidation were other features of carbonate sand that have been assessed with the cone pressuremeter. A numerical model which accounts for the crushing characteristics of carbonate sand is presented, and is shown to improve significantly predictions of limit pressure measured in the calibration chamber. Cone pressuremeter tests were carried out in soft clay at the Bothkennar test site in Scotland. An analysis based upon cavity expansion theory was shown to provide good estimates of undrained shear strength and stiffness compared with results from other in situ and laboratory tests. Estimates of the in situ horizontal stress were found to be unrealistically high. Shear modulus in both sand and clay has been measured from unload-reload cycles carried out during pressuremeter expansion. The stress levels and strain amplitudes of these cycles have been shown to influence the shear modulus greatly. In sand, a procedure for relating these moduli to those at an extremely small reference strain is presented. In clay, shear moduli are shown to give a remarkably close agreement to others reported from Bothkennar, when due account of the strain amplitude is made. Finally, a time/cost analysis between the cone pressuremeter, the cone penetrometer and the self-boring pressuremeter is presented. The cone pressuremeter is found to be a cost-effective device bearing in mind the amount and quality of information it can provide.
617

Investigations of suction caissons in dense sand

Byrne, Byron Walter January 2000 (has links)
Offshore structures are used in a variety of applications ranging from the traditional oil and gas extraction facilities to emerging renewable energy concepts. These structures must be secured to the seabed in an efficient and cost effective manner. A novel approach is to use shallow inverted buckets as foundations, installed by suction, in place of the more usual piles. These foundations lead to cost savings through reduction in materials and in time required for installation. It is necessary to determine how these foundations perform under typical offshore loading conditions so that design calculations may be developed. This thesis presents experimental data from a comprehensive series of investigations aimed at determining the important mechanisms to consider in the design of these shallow foundations for dense sand. Initially the long term loading behaviour (e.g. wind and current) was investigated by conducting three degree of freedom loading {V:M/2R:H} tests on a foundation embedded in dry sand. The results were interpreted through existing work-hardening plasticity theories. The analysis of the data has suggested a number of improved modelling features. Cyclic and transient tests, representing wave loading, were carried out on a foundation embedded in an oil saturated sand. The novel feature of the cyclic loading was that a 'pseudo-random' load history (based on the 'NewWave' theory) was used to represent realistic loading paths. Of particular interest was the tensile load capacity of the foundation. The results observed suggested that for tensile loading serviceability requirements rather than capacity may govern design. Under combined-load cyclic conditions the results indicated that conventional plasticity theory would not provide a sufficient description of response. A new theory, termed 'continuous hyperplasticity' was used, reproducing the results with impressive accuracy. Surprisingly, under the conditions investigated, loading rate was found to have a negligible effect on response.
618

A study of the cone-pressuremeter test in sand

Schnaid, Fernando January 1990 (has links)
The cone-pressuremeter is a new site investigation device which incorporates a pressuremeter behind a standard cone penetrometer tip. This dissertation is concerned with an understanding of the new device, and in particular the establishment of a detailed procedure to allow the test to be used to determine the engineering properties of cohesionless soils. A series of 34 calibration tests was performed, in which three cone-pressuremeter prototypes with cross-sectional areas corresponding to 15cm², 10cm² and 5cm² were used. The tests were carried out on cylindrical samples, enclosed in a chamber 1.0 m in diameter and 1.5 m in height. Stress controlled boundaries allowed independent control of vertical and horizontal stress in the range of 50 kPa to 300 kPa. A raining deposition technique was used to produce three sand densities, corresponding to loose, medium and dense samples. A programme of calibration was designed to provide an examination of the influence of relative density, stress level and stress ratio on cone-pressuremeter test data. Soil properties were related to the values of the limit pressure obtained from the pressuremeter test and the cone resistance values from the cone test. Empirical relationships were proposed for deriving density, friction angle and horizontal stress. Cone-pressuremeter tests were used for assessing directly the shear stiffness of the soil. A series of calibrations was needed to obtain the best possible estimation of the unload-reload shear modulus. Interpretation of the measured modulus was made by examining appropriate methods of calculating the modulus from unload-reload loops. Strain arm measurements and volume change measurements were compared. A method has been presented that allows the shear modulus values to be correlated to the relevant stress level acting around the pressuremeter during the test. The values of shear modulus obtained with the cone- pressuremeter were compatible with those obtained from the self-boring pressuremeter. An assessment of chamber size effects yielded useful information regarding the applicability of test correlations derived from calibration chambers to field problems. An additional study identified experimentally the influence of length to diameter ratio on the pressuremeter pressure-expansion curve.
619

Partially-drained loading of shallow foundations on sand

Mangal, Jan Krishna January 1999 (has links)
Wave loading on offshore structures founded on sand can result in partially drained response of the foundation soil. The characteristics of the rate of loading, the permeability of the soil, and the size of the foundation affect the degree of partial drainage. Partial drainage refers to situations where pore pressures develop in the soil, and the response of the soil is neither fully drained nor undrained. This thesis is concerned with the effects of loading rate, and consequent drainage, on the behaviour of a flat footing that is founded on the surface of a saturated sand base. The results of physical tests performed in the laboratory on a model-sized footing are reported. The footing was founded on oil-saturated fine sand and was subjected to combined loading. The effect of the vertical, horizontal, and rotational displacements are reported. The response of the footing is analysed in the context of existing drained foundation models that are based on work hardening plasticity theory. The rate dependency of the vertical load:deformation behaviour and the combined yield surfaces are described.
620

Extraction of bitumen from Athabasca oil sand slurry using supercritical carbon Dioxide

La, Helen 06 1900 (has links)
Extraction of hydrocarbons from an Athabasca oil sand slurry were conducted using supercritical carbon dioxide (SC-CO2). The oil sand was slurried to a 1:1 ratio with water and experiments were conducted using a laboratory-scale batch supercritical fluid extraction (SFE) system. Preliminary tests revealed the importance of mixing rate on hydrocarbon yields. A 2^3 factorial experiment was then conducted to test the effect of temperature, pressure, and modifier (toluene) addition on hydrocarbon extraction yield. When toluene was absent, hydrocarbon extraction yields were greater at the high temperature (60°C); however, when toluene was present, the combination of low temperature (31°C) and high pressure (24.1MPa) provided greater extraction yields. The experiment that produced the highest cumulative hydrocarbon extraction yield was analyzed by GC-FID for product-quality. Two composite samples and one time series sample revealed a carbon distribution range of the extract centering on C25, corresponding to the light gas oil range as classified in petroleum fractions. / Environmental Science

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