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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.

Energy-based mechanics of ballistic impact on ceramic/composite protective plates

Oberg, Erika Karin January 2014 (has links)
No description available.

Strategic environmental assessment and plan-making with a focus on regional planning

Gosling, James Anthony January 1999 (has links)
No description available.

Enviromental mining impact on soils around the abandoned Kgwakgwe Manganese mine, Botswana.

Ekosse, Ekosse Georges-Ivo January 2004 (has links)
Thesis (Ph.D)(Soil Mineralogy) --University of the North, 2004. / This research study focuses on environmental mining impact of soils around the abandoned Kgwakgwe Mn mine in Botswana. The thesis contains five chapters: introduction, methods and analytical techniques, results, interpretation and discussions, and conclusions. The physico-chemical properties, mineralogical identification and characterisation and chemical properties of soils and related geological materials as well as the chemical properties of the soils and leaves of plants around the abandoned mine were investigated in order to determine the mining impact on the surrounding soils. It mentions field research components, which included observation and sampling of surface soils, related geological materials and leaves of plants for different laboratory analyses. Methods, techniques and instrumentation for physico-chemical, mineralogical and chemical analyses are explained. Physico-chemical properties studied on soil samples included particle size distribution (PSD), pH, electrical conductivity (EC), soil colour, and descriptive petrography. Identification of minerals contained in soil samples which included both < 53 μm and < 4 μm size fractions were performed employing X-ray powder diffraction (XRPD) techniques. The < 4 μm size fractions of soil samples were further characterised using the environmental scanning electron microscope (ESEM) to which was fitted with an X-ray energy dispersive spectrometer (EDS). Chemical analyses for iron (Fe) and manganese (Mn) concentration levels in soil and leaf samples were measured with the flame atomic absorption spectrometer (FAAS). Determination of exchangeable bases (Na, K, Ca and Mg), cation echange capacity (CEC) and percent base saturation, viii P, Cl, SO4 and CO3 concentrations were performed only on the soil samples. The exchangeable bases, CEC and percent base saturation were determined using the ammonium acetate method which included flame photometry for K and Na, and AAS for Ca and Mg. The Olsen method was applied to determine P concentrations. Furthermore analyses for Cl and SO4 were done using ion chromatography, whereas the calcimeter was used to determine CO3 concentrations. A Quickbird 2.4 m – 2.8 m resolution with zero cloud cover multispectral standard imagery of the study area was processed to characterise the vegetation cover. The laboratory results were processed using Geographical Information Systems (GIS), and Remote Sensing (RS) techniques with the integrated Land and Water Information System (ILWIS), Geosoft Oasis Montaj and ArcGIS software packages. Microsoft Excel was used for statistical and graphical presentation of data analyses. The particle size distribution of soil samples revealed the average wt % of the soil fractions as follows: the < 4 μm fraction was between o.3 wt % and 30.58 wt %, and the < 53 μm fraction was between 11.05 wt % and slightly above 100 wt %. Soil pH ranged from 2.92 to 7.26 with very acidic soils located close to the mine workings. Electrical conductivity values were significantly low, and the range was from 49.1 μScm- 1 to 123.5 μScm- 1 . Dark brown to reddish brown soil colour was indicative of very high Fe and Mn levels in the soils. Bulk soil samples consisted of quartz, SiO2; haematite, Fe2O3; goethite, Fe+3O(OH); bixbyte, Mn2O3; braunite, Mn+2Mn6 +3SiO12 ramsdellite, MnO2; pyrolusite, MnO2; cryptomelane, K2-xMn8O16; sanidine, K(Si3Al)O8; microcline, KAlSi3O8; whereas the < 4 μm ix fraction was made up of kaolinite, Al2Si2O5(OH)4 illite, KAl2Si3AlO10(OH)2; and muscovite KAl2Si3AlO10(OH)2. The range of concentration levels of Fe in soils was from 1116 μg g-1 to 870766 μg g-1 with a mean of 17593 μg g-1 and for Mn in soils was 35 μg g-1 to 24907 μg g-1 with a mean of 1088 μg g-1. The values for Na concentration in the soil samples ranged from 0.1 cmolckg-1 to 89.1 cmolckg-1, with a mean of 0.44 cmolckg-1, and for K concentration in the soil samples values ranged from 0.1 cmolckg-1 to 163.6.1 cmolckg-1, with a mean of 0.82 cmolckg-1. The values for Ca concentration in the soil samples ranged from 0.3 cmolckg-1 to 1139 cmolckg-1, with a mean of 5.68 cmolckg-1, and values for Mg concentration in the soil samples ranged from 0.3 cmolckg-1 to 1655.3 cmolckg-1, with a mean of 8.26 cmolckg-1. The CEC values in the soil samples from the study area ranged from 1.1 cmolckg-1 to 29.2 cmolckg-1, with a mean of 8.2 cmolckg-1, and values for percent base saturation in the soil samples were from 33.77% to 100 % with a mean of 82.10 % cmolckg-1. Values obtained for P2O5 in some randomly chosen soil samples from the study area were from 0.51 mgkg-1 to 6.02 mgkg-1. The values for Cl concentration in the soil samples ranged from 0.2 mgkg-1 to 11.9 mgkg-1, with a mean of 7.63 mgkg-1, and for SO4 concentration in the soil samples values ranged from 2.1 mgkg-1 to 47.5 mgkg-1, with a mean of19.36 mgkg-1. The values for CO3 concentration (measured in terms of CaCO3 equivalent) in the soil samples ranged from 5.1 gkg-1 to 59.1 gkg-1, with a mean of 40.98 gkg-1. For the leaves, the range of concentration levels of Fe contained in them was from 101.2 μg g-1 to 3758 μg g-1 with a mean of 637 μg g-1 and for Mn in leaves, the range was from 26.2 μg g-1 to 3611.5 μg g-1 with a mean of x 598.4 μg g-1. The TOC values were between 0 wt % to 7.9 wt %. High acidity of soils is reflected by on-going neomineralisation activities which at some places are depicted by the formation of dead zones. Other observable phenomena were stunted growth of plants, and the yellowing of their leaves as a result of high concentrations of Fe and Mn in their organic systems. The gridded soil and vegetation maps for Fe and Mn show anomalies in different parts of the study area. Where Mn is high, the Fe is low and vice versa. Manganese was high at the mine workings and in the northwestern part of the study area. Iron on the other hand is very low in the mine working area and is high on the northern part of the study area. The mineral genesis is explained and a model is advanced for the Mn interplay in the soils and environment around the Kgwakgwe abandoned Mn oxides ore mine. Remediative measures for reclamation of the contaminated soils and appropriate land use of the area have been suggested. It is anticipated that these useful recommendations to stakeholders which have been suggested, and the direction for further research if adhered could bring solution to some of the environmental pollution problems in the study area.

Numerical Simulation of Impact Rollers for Estimating the Influence Depth of Soil Compaction

Kim, Kukjoo 2010 August 1900 (has links)
The use of impact rollers has increased for many decades over a wide variety of applications in various parts of the world. Many manufacturers have made claims that impact compaction rollers could have an effect to 1 m or more. In addition, other positive features such as greater depth of influence and faster travel speed than conventional rollers are being reported from the field. However, there is a lack of theoretical explanations or scientific research information for how to operate these rollers. Hence, this study will focus on a geotechnical modeling that describes the behavior of soils during ground compaction using various impact rollers (e.g., triangular, Landpac 3-sided, Landpac 5-sided, and octagonal shapes). In addition, this study will estimate more precisely the depth of influence for impact rollers. To do so, the general purpose finite element computer program LS-DYNA is used for numerical predictions. The finite element study is carried out with three-dimensional models. A simplified elastic perfectly plastic model with the Druker-Prager yield criterion is used for soil modeling and rollers are treated as a rigid body (i.e., incompressible material). The result of this study compares well with existing field experiment data for estimating vertical stress profile and compaction features, and demonstrates that the impact rollers are appropriate for thick layers.

A Study of the Hammer Impact

Hsu, Yu-ming 09 August 2006 (has links)
The purpose of this study is to investigate the impact effects of varied forms of a hammer on a nail of different material. To achieve the study purpose, the researcher integrated the computer-aided design software SoildWorks and finite element analysis software LS-DYNA to analyze some familiar hammer heads with varied shapes for striking nails. After observing the results of simulation, the researcher compared efficiencies of the physical properties and the mechanical effects. In addition, the researcher simulated different materials and sizes of the nail stricken by a hammer. He found out the best slenderness ratio of the nail. The researcher hoped that his study could provide the other designers to produce more effective hammers and nails.

Measuring the impact of an intensive commodity price risk management education program on agricultural producers

McCorkle, Dean Alexander 29 August 2005 (has links)
The purposes of the study were to measure change in knowledge, adoption of practices, and economic impact, and to investigate relationships between selected personal and business parameters, and satisfaction, knowledge, adoption of practices, and economic impact of the Master Marketer program and marketing clubs. A census was attempted to collect data from the 520 Master Marketer graduates and 1,058 marketing club members. Using recommendations from Dillman (2000), data from participants were collected using two mail questionnaires. This process yielded 326 usable responses from Master Marketer graduates for a return rate of 62.7%, and 407 usable responses from marketing club members for a response rate of 38.4%. Master Marketer respondents had a statistically significant increase in selfperceived knowledge with a change in mean score of 2.06 (pre-knowledge mean = 3.33, post-knowledge mean = 5.40, where 1 = low, and 7 = excellent). Using a paired samples t-test, the 2-tail level of significance was beyond the .05 level of significance. Marketing club respondents also showed a statistically significant increase in self-perceived knowledge. Adoption of price risk management practices was measured with an adjusted response scale ranging from 0 to 12. Master Marketer respondents showed a pre-mean score of 3.15, a post-mean score of 6.61, and a change of 3.46. The 2-tailed level of significance for the overall adoption scale was less than 0.01. Marketing club respondents also showed a statistically significant increase in adoption of these practices. Economic impact in terms of change in net income was derived using respondents?? self-reported changes in commodity price received for each commodity produced, and each respondent??s typical level of production. The total farm impact had a mean of $32,288. The 2-tailed level of significance for the total farm impact was less than 0.01. The mean impact per farm of $12,361 for marketing club respondents was also statistically significant. For Master Marketer respondents, notable findings with respect to the correlation of independent variable with dependent variables was total gross revenue was negatively correlated with knowledge change. Participants who reported a large change in knowledge tended to also report a large change (increase) in time spent on marketing.

A study of impact motion based on rheological modeling

Pugh, William Edward 08 1900 (has links)
No description available.

A comparison of two projectile configurations for impact testing

Haycock, Michael Stephen 08 1900 (has links)
No description available.

Probability of meteorite immpact in Sweden since year 2000

Wrige, Cecilia January 2015 (has links)
This Thesis investigates the number of possible meteorite impacts in Sweden since the year 2000. Sweden did not until recently have any photographic monitoring of incoming meteorites, thus a search through media reporting observations from the public has been performed. A theoretical approximation, based on an established extra-terrestrial mass ux, gives the number of 210 possible meteorite impacts for this time period. All of these could have been reballs, but by subtracting the daylight hours and bad weather conditions, only 47 reballs could have been seen during the 15 years. All of the 210 events could also have dropped meteorites on the ground, but when subtracting areas where it is very unlikely to recover a meteorite, like large forest areas and lakes, the number of possible meteorites is 73. The newspaper articles published since 2000 regarding reball observations gives 37 plausible meteorites. The theoretical value and the number of observations are similar enough that the theoretical approximation is probable to be correct.

Longitudinal wave transmission and impact

Donnell, Lloyd Hamilton, January 1900 (has links)
Thesis (Ph. D.)--University of Michigan, 1930. / Caption title. From Transactions of the American society of mechanical engineers, 1930. Applied mechanics.

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