Thesis (Ph. D.)--Universiteit Utrecht, 2001. / Includes bibliographical references (p. 163-171). "Publications: " p. 174.

The gopher tortoise is a land tortoise living in the southeastern United States. It is a species in decline and is listed as threatened or endangered in six different states. The gopher (as commonly referred) digs burrows that it uses for many reasons and spends most of its time underground. Problems occur when trying to estimate a population because a gopher tortoise digs more than one burrow. This thesis demonstrates an innovative way to survey and investigate a gopher tortoise burrow hole by using a multi-tracked remotely operated vehicle. The vehicle carried two cameras (fore and aft) and was equipped with a microphone and LED illumination. It has tracks on four sides to increase its propulsion ratio. Its performance was evaluated in a sand pit where parameters such as incline could be controlled, and in an actual tortoise burrow. This research was done in conjunction with the Hillsborough County Parks and Recreation Department.

The fundamental forces of adhesion are responsible for the spreading of fluids such as crude oil/brine on the reservoir rock surface. These physico-chemical interactions determine the surface energetics of a reservoir and thus their wetting phenomena. Inverse Gas Chromatography is introduced to characterize the surface energy of carbonates (calcite and dolomite) and sandstones (Ottawa sand and Berea sandstone). The behavior of the polar and non-polar interaction forces was investigated at varying water coverage and at different temperatures. The results indicated that in general as the water coverage increased, the Lifshitz-van der Waals component of surface energy decreased to nearly that of the bulk water, while the acid-base component also showed a decreasing trend. The Lifshitz-van der Waals component of surface energy always decreased with increase in temperature, while the acid-base properties mostly increased with temperature with the exception of calcite. / text

Evaluation of the effect of particle cementation on the stiffness of uniform sand was carried out by measuring compression wave velocities (VP) and shear wave velocities (VS) on both clean and artificially cemented specimens. Piezoelectric transducers (PT) were used to perform the majority of the measurements. Shear wave velocity (VS), shear moduli (G) and material damping ratio (D) of clean and artificially cemented specimens were also determined using resonant column (RC) testing. Linear (shearing strains ≤ 0.001%) and nonlinear (shearing strains > 0.001%) behavior of the specimens were evaluated in the resonant column tests. The sand selected for this investigation is commonly known as Hickory sand, from the Hickory formation, western Llano uplift, Texas. This material was selected for its grain geometry and gradation; it consists of uniformly graded sand with rounded particles. The sand specimens were artificially cemented with a solution of hydrated sodium silicate and water. Sodium silicate is an alkaline compound obtained from the reaction of sodium hydroxide and silica. All artificially cemented specimens and uncemented hickory sand specimens were formed by pluviation through air. The microstructure of the specimens was visually assessed with images obtained from both optical and scanning electron (SEM) microscopes. These images confirmed that the procedure used to form artificially cemented specimens provides cementation around the contacts while some grain-to-grain contact appears to be preserved. Seismic and drained strength measurements on Hickory sand specimens were obtained from different cement concentrations and compared with results from clean sand specimens. Among the findings of this investigation are: (1) the procedure to artificially cement sand specimens in the laboratory was successful, (2) the slopes (nP and nS) obtained from the relationships between compression and shear wave velocities with effective isotropic confining pressure in log-log scale decrease as the cement content increases, and (3) as increasing amounts of cement are added to the sand particles, the nonlinearity of the specimens increases up to certain amount of cement, after which the nonlinearity of the specimen decreases and tends towards rock-like behavior. / text

This dissertation is concerned with a study of soil nailing, in particular the interaction mechanism between the soil and a nail and the failure mechanism and suitable design procedure for nailed slopes in sand. The interaction mechanism of a nail was studied by carrying out a number of pull-out tests, direct shear tests of nailed sand and interface tests using two uniform sands. Major parameters of the tests were flexibility, surface roughness and diameter of a nail. From the tests, it was found that: (1) flexibility of a nail significantly influences the interaction mechanism. Both the interaction parameter and apparent friction coefficient differ between a flexible and a stiff nail. Theoretical consideration indicates that the mobilization of nail forces is dominated by the relative stiffness between soil and nail. (2) a smooth-surface nail produces smaller bond friction than the critical state friction angle and mineral-to-mineral angle of the soil. This is due to the very thin rupture surface developed around the nail. On the other hand, a rough-surface nail was observed to produce two to four times larger bond friction than the direct shear friction angle of sand, due to the thick rupture surface developed and the dilatancy of the soil. (3) increasing the diameter of a nail produces a smaller apparent friction coefficient. Restrained dilatancy was found to play an important role. (4) the pull-out test, direct shear test of nailed sand and interface test produce different values of apparent friction coefficient , due to the different amount of restrained dilatancy effect around the nail (or reinforcement). The overall behaviour of nailed slopes was studied by carrying out a comprehensive series of centrifuge tests. Excavation of soil was simulated by draining water from two rubber bags in front of the facing wall. The centrifuge tests have provided much useful information on the mechanics of soil nailing. From the tests, it was found that: (1) draining of the water significantly influences both the earth pressure on the facing wall and the displacements of the nailed slope. Horizontal displacements of the facing wall were decreased by increasing the length and/or friction (bond) of the nail. (2) earth pressures on the facing wall do not exhibit a simple hydrostatic distribution. The deviations of the earth pressure are not negligible especially near the top and bottom of the facing wall. (3) roughness and bending stiffness of the facing wall considerably influence the stability and displacement of the nailed slope, respectively. (4) the observed failure surfaces were well described by a logarithmic spiral passing through the toe of the facing wall. (5) fairly good predictions for the failure acceleration were made using stability analysis of the nailed slopes based on the limit equilibrium method, provided an accurate friction angle for the sand and pull-out resistance of each nail could be determined. The factor of safety F5 of the nailed slopes was estimated by comparing the total available force and the total required force based on the observed failure surfaces.

The work presented aims to find alternatives for the prototyping of components by sand and plaster mold manufacturing processes that deliver properties similar to high pressure die casting (HPDC). Sand and plaster test samples have been casted. The Al-7Si-0.35Mg alloy has been tested in as cast condition and in a heat treated condition; T5 for sand cast samples and T6 for those plaster cast. The Al-7Si-2Cu-0.35Mg alloy was also tested in as cast condition. Tensile, fatigue and hardness tests have been performed. Microstructural investigation comprising secondary dendrite arm spacing, defects, Fe-rich β-phases and Si size measurements has been performed on the different conditions. The results have been compared to available data for Al-9Si-3Cu-(Fe) alloy used in HPDC. The T5 heat treated sand cast condition has shown to have properties similar to HPDC. All other sand cast conditions, including the previously tested Al-9Si-3Cu-(Fe) alloy, have been shown to be reasonable alternatives.

In this thesis, I will study two manifestations of the legacy of Jean-Jacques Rousseau’s educational and political theories between 1832 and 1833: George Sand’s Indiana (1832) and Honoré de Balzac’s Eugénie Grandet (1833). I will argue that both novels treat the difficulties that uneducated or domestically educated young women face when they first encounter the artificial relationships of society, and that both authors attribute their protagonists’ situation to the lack of connection between the ideology of their upbringing and that of society. Furthermore, I will view these texts within the context of Romanticism, which buoyed the influence of Rousseauvian thought in the early nineteenth century by declaring nature preferable to society, a critical tenet of Rousseau’s theories. Social and political changes, however, led to Romanticism’s decline as the nineteenth century progressed, and this waning influence, coupled with the rise of Realism, can be observed in Indiana and Eugénie Grandet. The first chapter of this work will discuss the ideas that Rousseau presents in Emile, ou de l’éducation (1762) and the Discours sur l’origine et les fondements de l’inégalité parmi les hommes (1754). Although women are painted as independent in the original state of Nature, Rousseau argues in Emile that they should be domesticated in society, and he outlines the male and female educations that he believes will best prepare men and women for their assigned gender roles in society. The two chapters that follow treat the interpretations of Rousseau’s theories that Sand and Balzac put forward in Indiana and Eugénie Grandet. Sand refutes the nineteenth-century discourse concerning women’s innate “irrationality,” attributing Indiana’s difficulties with love and social norms to the distance between her “natural” education on Ile Bourbon and the artificiality of French relationships, eventually rejecting the possibility that reformed education can purge society of its corruption. Balzac, meanwhile, traces Eugénie’s transition from naïve young woman to true adulthood, when she is versed in the relations of “intérêt” that govern those around her. Eugénie, raised to base her relationships on true affection, is eventually isolated by her education, but Balzac does not envision her possible escape from society. / text

The overall objective of the present study was to evaluate the effectiveness of using a variety of hydrophobic biopolymers and hydrophobic biopolymer-coated sands as technically and economically feasible in-situ sediment amendments or alternative capping materials on a laboratory scale. Cutin from tomato peels, cellulolytic enzyme lignin from sitka spruce chips, and keratin azure from commercially dyed sheeps wool were isolated, prepared, tested, and evaluated as feasible hydrophobic biopolymers for the removal of selected Polycyclic Aromatic Hydrocarbons (PAHs). Testing included chemical and physical characterization, as well as the measurement of kinetics and equilibrium sorption parameters for the sorbates naphthalene, phenanthrene, and pyrene as model hydrophobic organic contaminants. Tomato peel cutin exhibited the largest overall affinity for PAHs, however, keratin azure was selected for further evaluation as the most feasible material due to its low preparation cost. Amendment of industrial sand with a stable, uniform, cross-linked keratin azure derivative was achieved to produce hydrophobic biopolymer-coated sand products containing zero, moderate, and high mass fractions of sand. Chemical and physical material parameters, as well as kinetics and equilibrium sorption parameters for the sorbates naphthalene, phenanthrene, and pyrene, were then obtained for the coated sand products. This allowed simple finite difference modeling of PAH fate and transport through a thin cap comprised of the same, insight into the specific sorption mechanisms involved, and information which could prove useful in predicting potential of keratin products to provide a suitable capping material. Conclusions and recommendations for future research focus on the technical and economical feasibility of the prepared hydrophobic biopolymers and hydrophobic biopolymer-coated sand products as capping or in-situ sediment amendments. / text

No description available.

Baigiamajame magistro darbe analizuotos skirtingi liaunų atraminių sienų įrengimo variantai. Joms sumodeliuot ir paskaičiuot panaudota Prosheet ir GEO4 programos. Analizuojamos atraminės sienos, įrengtos smėliuose, kurių vidinės trinties kampas φ = 30 , sankabumas c = 0 kPa, ir moliuose, kurių vidinės trinties kampas φ = 26 , sankabumas c = 15 kPa. Skaičiavimų rezultatų lentelėse pateiktos įražų reikšmės ir skirtumai pavaizduoti grafiškai. Taip pat buvo išanalizuota, polių ilgiai, kuriuos suskaičiuoja kiekviena programa ir pavaizduota grafiškai. Išnagrinėjus, dėl ko gaunami skirtingi rezultatai, pateikiamos baigiamojo darbo išvados. Darbą sudaro 7 dalys: įvadas, 4 teorinės dalys, penktoji dalis - skaičiavimų rezultatai, išvados, literatūros sąrašas. Darbo apimtis – 63 p. teksto be priedų, 72 p. skaičiavimų rezultatų, 89 iliustr., 28 lent. Atskirai pridedami darbo priedai: 1 priedas 168 p. ir 2 priedas 168 p.. Priedai yra projektavimo programų atskirų variantų rezultatai, 3 priedas – paruoštas straipsnis vienuoliktai Lietuvos jaunųjų mokslininkų konferencijai bei pažyma apie straipsnio priėmimą spausdinimui. / In the master thesis it was analysed different method of retaining walls contruction. Prosheet and GEO4 programs werw used for calculation and design. Retaining walls were constructed in sandy soil or in clay. Properties of sand: angle of internal friction φ = 30 , cohesion c = 0 kPa. Properties of clayer soil: φ = 26 , c = 15 kPa. The stress values are given in the tables and differences showen graphically. Lengths of piles calculated are using each programme were analyzed and given graphically. After analysis of results, there were formulated an conclusion. Thesis consist of 7 chapters: introduction, 4 theoretical chapter, results of calculations, conclusions and references. Thesis consist of 63 text pages, 73 pages of calculations, including 89 illustrations and 28 tables. In addition 3 annexes are attached. Two of them are calculations and an article in the Young scientists conference.