Constitutive behavior models for steels are typically semi-empirical, however recently neural network is also being used. Existing neural network models are highly complex with a large network structure i.e. the number of neurons and layers. Furthermore, the network structure is different for different grades of steel. In the present study a simple neural network structure, 3:4:1, is developed which models flow behavior better than other models available in literature. Using this neural network structure constitutive behavior of 8 steels: 4 carbon steels, V and V-Ti microalloyed steels, an austenitic stainless steel and a high speed steel could be modeled with reasonable accuracy. The stress-strain behavior for the vanadium microalloyed steel was obtained from hot compression tests carried out at 850-1150 C and 0.1-60 s-1. It is found that a better estimate of the constants in the semi-empirical model developed for this steel could be obtained by simultaneous nonlinear regression. A model that can predict the effect of chemical composition on the constitutive behavior would be industrially useful for e.g., in optimizing rolling schedules for new grades of steel. In the present study, a neural network model, 5:6:1, is developed which predicts the flow behavior for a range of carbon steels. It is found that the effect of manganese is best accounted for by taking Ceq=C+Mn/6 as one of the inputs of the network. Predictions from this model show that the effect of carbon on flow stress is nonlinear. The hot strip mill at Jindal Vijaynagar Steel Ltd., Toranagallu, Karnataka, India, was simulated for calculating the rolling loads, finish rolling temperature (FRT) and microstructure evolution. DEFORM-2d a commercial finite element package was used to simulate deformation and heat transfer in the rolling mill. The simulation was carried out for 18 strips of 2-4 mm thickness with compositions in the range and 0.025-0.139 %C. The rolling loads and FRT could be calculated within 15 % and 15 C respectively. Analysis based on the variation in the roll diameter, roll gap and the effect of roll flattening and temperature of the roll showed that an error of 6 % is inherent in the prediction of loads. Simulation results indicated that strain induced transformation to ferrite occurred in the finishing mill. The microstructure after rolling was validated against experimental data for ferrite microstructure and mechanical properties. The mechanical properties of steels with predominantly ferrite microstructures depend on the prior austenite grain size, strain retained before transformation and cooling rate on the run-out table. A parametric study based on experimental data available in literature showed that a variation in cooling rate by a factor of two on the run-out table gives rise to only a 20 MPa variation in the mechanical properties.

Aujourd'hui le monde des télécommunications est en plein essor et le nombre de services proposés aux consommateurs augmente d'année en année. Les technologies employées font appel à l'optique. Le simple constat du nombre d'applications "sans fils" qui se développent permet de se rendre compte de l'importance des microondes dans l'ensemble des technologies modernes de communication. Cette thèse se situe dans ce cadre. Elle présente des techniques de modélisation de base pour concevoir et optimiser un guide d'onde de surface fonctionnant dans le domaine des microondes. Dans le premier chapitre, des outils de simulation permettant de calculer la réponse de diffraction par les réseaux de strips métalliques ont été développés. Les méthodes rigoureuses qui ont été retenues sont la méthode MMFE, CBCM et la méthode C qui prennent en compte la nature vectorielle de la lumière. La difficulté de convergence des calculs numériques et le problème de discontinuité des champs sur les strips métalliques est mise en évidence. Pour traiter ces problèmes, un changement de coordonnées est proposé, c'est le système de " Coordonnées adaptative " qui permet de resserrer les lignes de coordonnées au voisinage des points des discontinuités. Il en résulte une diminution du saut de discontinuité en ces points et une amélioration de la convergence des calculs numériques. Dans le second chapitre, ces méthodes sont étendues au problème de la diffraction en incidence oblique encore appelé diffraction conique. Dans le troisième chapitre, nous avons appliqué ces méthodes pour étudier et caractériser les réseaux de strips métalliques déposés sur une couche diélectrique. Nous avons mis en évidence le phénomène de résonance sur les facteurs de réflexion et nous avons pu montré que ces effets des résonances sont dus au couplage de l'onde de surface et de l'onde plane incidente. Afin d'analyser les couplages résultants qui existent entre le mode, nous avons étudié les pôles de la matrice S et déterminé la sensibilité et l'influence des paramètres optoélectroniques sur le pic de résonance. Cette étude a permis de déterminer le triplet (hauteur, facteur de forme, l'angle de polarisation ) relatif à la structure pour que le guide soit optimisé.

This study investigated the relative clause formation and the coding of tense in the English interlanguage of thirty-two Palestinian students at the six colleges of the Islamic University of Gaza.Three composition topics were designed to elicit the learners' expression of the various English tenses and relative clauses.Findings: The data show that Palestinian learners' switching of tense results from using English morphology to express an aspectual system similar to that of Palestinian Arabic. The English past tense and present tense are used to mark Palestinian perfective and imperfective aspects, respectively. The subject-verb agreement marker and the concord markers 's/is and 'm/am are omitted in relative clauses and when there is a change in aspect.In the area of relative clauses, the data show that relative clauses are ninety percent independent of the Palestinian Arabic structuring of relative clauses. The learners use resumptive pronouns not only in clauses where the predicate incorporates a noun, adjective, or a prepositional phrase, but also before verbs. Conclusions:1. There is a large amount of influence from the Palestinian aspectual system on the learners' use of English tense.2. Subject-verb agreement problems can be solved when the problem of tense shift is solved, because of the cooccurrence of these phenomena.3. EFL teachers in Gaza Strip should not over-react to their students' tense usage in narrative passages and should not require them to write in a particular tense in an artificial manner.4. The learners' errors should be tolerated and should not be considered as indications of faulty learning.

Baigiamajame magistro darbe atliekami eksperimentiniai gelžbetoninių sijų, sustiprintų pneumatiniu montažiniu pistoletu mechaniškai tvirtinama anglies pluošto juosta, elgsenos tyrimai, nagrinėjama jungių skaičiaus ir išdėstymo įtaka sijos elgsenai. Darbą sudaro: įvadas, trys pagrindiniai skyriai, pasiūlymai ir išvados, literatūros sąrašas. Įvade aptariama tiriamoji problema, darbo aktualumas ir naujumas, pristatomas darbo objektas, formuluojami tikslai ir uždaviniai, pateikiama tyrimų metodika. Pirmajame skyriuje pateikiamos bendros žinios apie sijų stiprinimą, apžvelgiama stiprinimo metodų raida, aptariamos statybiniams kompozitams gaminti naudojamos medžiagos ir aprašomi populiariausi metodai, naudojami statybiniais kompozitais sustiprintų sijų skaičiavimui. Antrajame skyriuje plačiau aptariamas sluoksnių skaičiavimo metodas, atliekama jo parametrinė analizė. Trečiajame skyriuje plačiai aprašomas bandinių paruošimas ir jų bandymo metodika, pateikiami eksperimentinių tyrimų rezultatai, jie palyginami su teoriniais skaičiavimais bei kitų autorių gautais rezultatais. Darbo pabaigoje pateikiami sijų stiprinimo pneumatiniu montažiniu pistoletu mechaniškai tvirtinama anglies pluošto juosta pasiūlymai, formuluojamos išvados. Darbo apimtis – 69 p. teksto be priedų, 33 paveikslai, 5 lentelės, 32 bibliografiniai šaltiniai. / This thesis presents the analysis based on experimental testing of reinforced concrete beams, strengthened by mechanically fastened fiber reinforced polymer strips, when high pressure air powered pinner was used to fasten the strips. The influence of the number and arrangement of fasteners is investigated. Thesis consists of introduction, three main chapters, recommendations and conclusions, literature list. The introduction presents an overview, objectives, scope, methodology and significance of thesis. The first chapter shows the development of beam strengthening, introduces composite materials and methods used for calculating beams strengthened using FRP strips. In the second chapter the chosen calculation method is described in detail and its parametric analysis is performed. Third chapter gives a detailed description on the test specimen preparation and the methodology of testing. Experimental results and their comparison with theoretically obtained values and values obtained by other researchers are given here. The recommendations on the technology of strengthening the beams using mechanically fastened fiber reinforced polymer strips are given and the conclusions are drawn. Thesis contains 69 pages. There are 33 pictures, 5 tables and 32 references in the thesis.

Understanding the bearing response of the footings on layered soils has always been a challenge for researchers. Due to the limitations of analytical and empirical solutions it had been difficult to understand the true bearing behavior. Some researchers have tried solving this problem by numerical analysis and have found some success. In this study the numerical analysis approach has been applied using a commercial tool FLAC (Fast Lagrangian Analysis of Continua) to study the bearing response of surface footings on layered clays. First, small deformation analyses were taken up to study the undrained bearing response of strip and circular footings resting on a horizontally layered strong over a soft clay foundation, and then over soft over strong clay foundation. In the end application of large strain mode of FLAC was explored to investigate the large deformation behavior of the strip footing resting on the surface of a strong over soft clay foundation. All models were run by applying velocity loading and a elastic-perfectly plastic Tresca yield criterion has been used. The results are compared with published Finite Element Method (FEM) results, and with analytical, empirical and semi-empirical solutions. It was found that bearing capacity results from the present small-strain FLAC analyses agree well with the FEM results. However, these results in most of the cases tend to differ (as much as 49% for certain layered clay foundations) from those predicted with analytical, empirical and semi-empirical solutions, mainly due to the assumptions made in these solutions. Since no such assumptions are made in the present FLAC analyses, the results and the methodology of this thesis can be applied to predict the bearing capacity of the practical problems. Application of the large-strain mode of FLAC to study the large deformation of shallow foundations has pointed out a limitation of FLAC in completing such analyses. However, it is observed from the early trends of these analyses that whereas the small deformation analysis may under estimate the ultimate bearing capacity for certain cases of layered foundations where the upper clay is moderately stiffer than the lower clay layer, it might also over predict the ultimate bearing capacity for other cases when the upper clay is very stiff in comparison to the lower clay layer.

Understanding the bearing response of the footings on layered soils has always been a challenge for researchers. Due to the limitations of analytical and empirical solutions it had been difficult to understand the true bearing behavior. Some researchers have tried solving this problem by numerical analysis and have found some success. In this study the numerical analysis approach has been applied using a commercial tool FLAC (Fast Lagrangian Analysis of Continua) to study the bearing response of surface footings on layered clays. First, small deformation analyses were taken up to study the undrained bearing response of strip and circular footings resting on a horizontally layered strong over a soft clay foundation, and then over soft over strong clay foundation. In the end application of large strain mode of FLAC was explored to investigate the large deformation behavior of the strip footing resting on the surface of a strong over soft clay foundation. All models were run by applying velocity loading and a elastic-perfectly plastic Tresca yield criterion has been used. The results are compared with published Finite Element Method (FEM) results, and with analytical, empirical and semi-empirical solutions. It was found that bearing capacity results from the present small-strain FLAC analyses agree well with the FEM results. However, these results in most of the cases tend to differ (as much as 49% for certain layered clay foundations) from those predicted with analytical, empirical and semi-empirical solutions, mainly due to the assumptions made in these solutions. Since no such assumptions are made in the present FLAC analyses, the results and the methodology of this thesis can be applied to predict the bearing capacity of the practical problems. Application of the large-strain mode of FLAC to study the large deformation of shallow foundations has pointed out a limitation of FLAC in completing such analyses. However, it is observed from the early trends of these analyses that whereas the small deformation analysis may under estimate the ultimate bearing capacity for certain cases of layered foundations where the upper clay is moderately stiffer than the lower clay layer, it might also over predict the ultimate bearing capacity for other cases when the upper clay is very stiff in comparison to the lower clay layer.

[Truncated abstract] Mine lakes are a water body created after an open-cut mine ceases operating. The lakes develop in the former mine-pit due to the combination of groundwater inflow, surface run-off and, in some cases, due to rapid filling from river diversion. While potentially valuable water resources, these lakes often have poor water quality and managing the water body is an important part of the overall process of mine site rehabilitation. As mine lakes form in man-made pits, they have a bathymetry that is typically quite distinct from natural lakes and this can, in turn, strongly influence the hydrodynamics and hence the water quality of the water body. Despite the potential importance of these water bodies, there have been very few studies on the hydrodynamics of mine lakes. This study describes a field investigation of the hydrodynamics of a former coal mine lake, Lake Kepwari, in south-western Western Australia. In particular, this study examines the hydrodynamic processes in both the surface mixing layers and the internal mixing in the density stratified lake. Wind sheltering in the surface mixing layer occurs due to the presence of the steep walls and lake embankments. A week long field experiment was conducted in December 2003 using a combination of moored thermistor chains with meteorological stations and the deployment of rapid vertical profiling turbulent microstructure instruments and CTD drops from two boats operating on the lake. ... Simulations indicated that inclusion of a site specific sheltering effect, based on the results of the field campaign, significantly improved the models‘ performance in capturing the surface mixed layer deepening associated with episodic strong wind events that occur on the lake. Considerable internal mixing was indicated by the high dissipation rates observed, particularly near the boundaries. Large basin-wide diffusivities were also calculated from the heat budget method over long periods, showed a consistency with time, and were slightly higher in summer than during the Autumn Winter period. Although light, there are persistent winds over the lake and yet little basin-scale internal wave activity or seiching. It is hypothesized that any seiching motion was rapidly damped by strong mixing over the hydraulically rough bathymetry bathymetry created by the remnant benches from the open cut mining operation itself. This boundary mixing, in turn, drives secondary relaxation currents that transport mixed fluid from the boundaries to the interior, resulting in high effective basin-wide diffusivities. A simple boundary mixing model is proposed to describe this process.

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

Thesis (M.S.)--University of Tennessee, Knoxville, 2008. / Title from title page screen (viewed on Feb. 26, 2009). Thesis advisor: Mark Littmann. Vita. Includes bibliographical references.

Thesis (MScFor)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Namaqualand has a very unusual diversity of plant life, with many endemic plant species. The fundamental question of this thesis is how this system, damaged by strip-mining activities, can be rehabilitated. The aim was to base the rehabilitation methods on ecological processes. In order to answer this question an overview of the relevant literature was needed in order to identify possible research needs and also to evaluate the work that has been done in the field of strip-mine rehabilitation in arid areas. An understanding of community and ecosystem dynamics would help to establish aims and methods for site-specific rehabilitation. In Namaqualand, South Africa, there is also a need for experimentation to establish which of the many factors is most limiting to long-term ecosystem recovery. It is important to have a good knowledge of the successional processes and disturbance history of the land which needs to be rehabilitated. The vegetation on unmined areas and mined areas of different ages and treatments after mining, were sampled. It was shown that some areas could be expected to show a large degree of recovery in the space of a few years, whilst others would show little or no recovery over a period of decades. It is important to recognise rehabilitation as a gradual process that takes place at different rates in different areas and in different years. The planting of Atriplex nummularia and sowing of Atriplex semibaccata did not facilitate the return of indigenous, perennial species, but rather seem to inhibit their return. In view of the importance of topsoil in terms of the fertility of the soil and the seed bank present in the topsoil, the influence of topsoil removal and stockpiling due to strip-mining activities were tested. The soil fertility was tested by means of radish bioassays and soil laboratory analysis, whilst species diversity and richness were tested with seedling emergence trials. As expected a higher plant species diversity was found on the unmined soils and radishes grew larger on these soils. The topsoil deteriorated in terms of plant species richness, diversity and soil fertility whilst it was stockpiled. Direct replacement of topsoil would ensure a planting medium closer to the pre-disturbance level that could lead to fairly rapid and successful recolonization of the mined area. Successful plant recruitment also depends on the microsites to which seeds are dispersed. The effect that different microsites had on seed germination, seedling growth and survival was tested. It was found that micro catchments always yielded the highest numbers. The establishment and survival of seedlings in the other microsite types (under single shrubs, under clumped shrubs and in the open) varied, depending on the amount of rainfall received in the particular year. Lastly, I experimented with the translocation of three local, indigenous, succulent plant species. These plants were transplanted either in clumps of three together or alone, since I hypothesized that planting them together would facilitate their survival. However, it was found that it depended largely on the morphology of the plant and the amount of rainfall received in a particular year, whether these plants will compete with each other for limiting resources or facilitate each other's survival. The thesis contributes to the understanding of vegetation dynamics in the Succulent Karoo after strip-mining has taken place. Guidelines are provided based on ecological processes, for strip-mine rehabilitation in the Succulent Karoo. / AFRIKAANSE OPSOMMING: Namakwaland is bekend vir sy ongewone diversiteit van plante, met baie endemiese spesies. Die fundamentele vraag wat deur hierdie tesis gevra word is hoe hierdie sisteem, wat beskadig is deur oppervlak mynbou, gerehabiliteer kan word. Die doel is om die rehabilitasie metodes te baseer op ekologiese prosesse. 'n Oorsig van die relevante literatuur was nodig om moontlike areas van verdere navorsing te identifiseer en ook die navorsing wat reeds gedoen is oor rehabilitasie van oppervlak myne in ariede gebiede, te evalueer. 'n Goeie begrip van gemeenskap en ekosisteem dinamika sal help om doelwitte en metodes daar te stel vir die rehabilitasie van spesifieke areas. Dit is ook nodig om in Namakwaland, Suid -Afrika, uit te vind watter van die baie faktore, die lang-termyn herstel van 'n ekosisteem, die meeste verhinder. Dit is baie belangrik om In goeie kennis te hê van die versteurings geskiedenis van die area wat gerehabiliteer moet word, asook die suksessionele prosesse wat werksaam is. Plantegroei van areas wat op verskillende tye gemyn en verskillend behandel is, asook ongemynde areas is ondersoek. Sekere areas het In groot mate van herstel gewys in 'n tydperk van 'n paar jaar, terwyl ander, min of geen hersteloor 'n periode van dekades getoon het nie. Dit is belangrik om rehabilitasie as 'n geleidelike proses te sien, wat teen verskillende tempos plaasvind tydens verskillende jare en in verskillende areas. Daar is bevind dat die plant van Atriplex nummularia asook die saai van Atriplex semibaccata nie die terugkeer van inheemse, meerjarige spesies bevoordeel nie, maar dit eerder inhibeer. Aangesien die bo-grond so belangrik is in terme van die grondvrugbaarheid en ook die saadbank wat teenwoordig is, word die invloed van die verwydering en opberging van die bogrond getoets. Die grondvrugbaarheid was bepaal deur groei-toetse op radyse en laboratorium analise op die grond te doen. Die plant spesie diversiteit en rykheid was bepaal met In saad ontkieming studie. In ooreenstemming met die verwagte uitkoms, was die plant spesie diversiteit hoër op die ongemynde bo-grond en die radyse het groter geword op dieselfde grond. Dit kom voor asof die plant spesie diversiteit en rykheid, asook die grond vrugbaarheid afneem met tyd wat die bo-grond geberg word. Die direkte verspreiding van die bo-grond nadat dit verwyder is, sal In medium vir die plante verseker wat nader is aan die vlak voordat die grond versteur is. Dit sal oak sorg vir redelike vinnige en suksesvolle terugkoms van plante op die gemynde grond. Die suksesvolle vestiging van plante hang ook af van die mikro areas (klein areas in terme van die grootte van 'n saad, wat In eie mikro-klimaat vorm), waarna saad versprei word. Die effek van sulke mikro-gebiede op die ontkieming van saad, die groei van die saailinge en die oorlewing van die saailinge was bepaal. Mikro-water- opvanggebiede het in al drie bogenoemde gevalle die hoogste syfers getoon. Die vestiging en oorlewing van saailinge in die ander mikro-gebiede (die area onder enkel struike, die area onder groepe struike en oop areas) het gevarieer afhangend van die hoeveelheid reënval wat ontvang is in die spesifieke jaar. Laastens, is daar ge-eksperimenteer met die oorplant van drie plaaslike, inheemse, sukkulente spesies. Hierdie plante was alleen geplant of in groepies van drie, bymekaar. Die hipotese was dat huloorlewingskanse beter sal wees as hulle saam geplant word. Dit was egter bevind dat die hoeveelheid reënval in 'n spesifieke jaar en die morfologie van die plant, bepaal of hulle sal kompeteer vir die beperkte bronne en of hulle deur saam te groei huloorlewingskanse sal verhoog. Hierdie tesis dra by tot die verstaan van die plantegroei dinamika in die Sukkulente Karoo nadat oppervlak mynbou plaasgevind het. Riglyne vir die rehabilitasie van oppervlak myne, gebasseer op ekologiese prosesse, word ook voorgestel.