Made available in DSpace on 2016-06-02T20:00:25Z (GMT). No. of bitstreams: 1 DissSACP.pdf: 1613507 bytes, checksum: b6db1a7b3fcc5b52e068951b4bd61381 (MD5) Previous issue date: 2003-08-27 / A new lifestyle, with changes in the consumption patterns and generation of residues, is imposed for humanity in Brazil, the growth of the cities and, at the same time, the increase in the consumption of industrialized products, are common factors to practically all the municipal districts. This way serious problems have been carted, regarding the inadequate administration of the urban solid residues (USW) generated. Because of its great number, the small municipal districts contribute with the current environmental and social problems. Thus, one of the main measures to be taken to correct this situation is the establishment of plans of the Management of USW (PMUSW) generated in such municipal districts. The present work lifted some concepts and administration models and management of USW, seeking to supply advices for the elaboration of PMUSW to small municipal districts, based in the minimization concepts. The small municipal districts can count with some facilities for an integrated administration of the different residues, especially the communication with the population, the inspection of the proposal measures, the organization of the society in the administration process of RSU. Besides, the amount of generated residues is smaller and the segregation process, collection and disposition can be simplified. On the other hand, such municipal districts face difficulties for the implantation of a good administration of USW, among them the lack of financial and human resources. Taking into account such characteristics, some guidelines were systematized and established some procedures that better adapt to the referred municipal districts, contemplating simplified solutions, of low cost, accessible to technicians and administrators without specialization in the theme and that involve the population. Such orientations were applied to a specific case of the small municipal district of (Itamogi-MG), allowing its evaluation by means of the elaboration of local PMUSW. In conclusion, it is possible to propose an administration of USW that assists the needs and limitations of those municipal districts. / Um novo estilo de vida, com mudanças nos padrões de consumo e de geração de resíduos, se impõe para humanidade. No Brasil, o crescimento das cidades e, ao mesmo tempo, o aumento de consumo de produtos industrializados, são fatores comuns a praticamente todos os municípios. Deste modo, graves problemas têm sido acarretados, no que diz respeito à gestão inadequada dos resíduos sólidos urbanos (RSU) gerados. Em função do seu grande número, os municípios de pequeno porte contribuem com os problemas ambientais e sociais decorrentes. Assim, uma das principais medidas a serem tomadas para corrigir esta situação é o estabelecimento de Planos da Gestão dos RSU (PGRSU) gerados em tais municípios. O presente trabalho levantou alguns conceitos e modelos de gestão e gerenciamento de RSU, visando fornecer orientações para elaboração de PGRSU para municípios de pequeno porte, embasados nos conceitos de minimização. Os municípios de pequeno porte podem contar com algumas facilidades no que diz respeito a uma gestão mais integrada dos diferentes resíduos, em especial a comunicação com a população, a fiscalização das medidas propostas, a organização da sociedade no processo gestão dos RSU. Além disto, a quantidade de resíduos gerados é menor e os processos de segregação, coleta e disposição podem ser mais simplificados. Por outro lado, tais municípios enfrentam dificuldades para a implantação de uma boa gestão dos RSU, entre elas a falta de recursos financeiros e humanos. Levando em conta tais características, foram sistematizadas algumas diretrizes e estabelecidos alguns procedimentos que melhor se adaptem aos referidos municípios, contemplando soluções simplificadas, de baixo custo, acessíveis a técnicos e administradores sem especialização no tema e que envolva a população. Tais orientações foram aplicadas a um caso específico de município de pequeno porte (Itamogi-MG). Como produto final, foi elaborado um PGRSU, incorporando características locais previamente identificadas, tanto de ordem geral como relativas aos RS. A metodologia empregada nesta elaboração mostrou-se adequada para definir uma gestão dos RSU que atenda as necessidades e limitações desses municípios.

Made available in DSpace on 2015-03-26T14:01:06Z (GMT). No. of bitstreams: 1 texto completo.pdf: 314822 bytes, checksum: 5b2d05d7e90ad2be423641cfa4c9b2a8 (MD5) Previous issue date: 2010-07-09 / Historically, the pulp and paper industry has been one of the largest consumers of natural resources. The volume of water consumed in the sector reaches an average value of about 25 to 100 m3 per ton of pulp produced. Among the stages that comprise the kraft process, the bleaching plant is the largest source of liquid effluent generation. Reducing effluent generation, through partial or total system closure, significantly reduces fresh water consumption and brings benefits in terms of reduction of environmental pollution. The purpose of this work was to evaluate the feasibility of reducing fresh water consumption in the bleaching system, through the recirculation of bleaching filtrates. From the current conditions of pulp process of Lwarcel Celulose Ltda, which has total effluent generation of 22 m3/adt, two degrees of closure were analyzed, generation 19,5 and 17,5 m3/tsa. Based on these conditions, the final product quality, concentration and influence of non-process elements (NPEs) in the circuit, reagent consumption on bleaching and concentration of effluent generation were analyzed. Results indicate that as the circuit was closed, the concentration of non-process elements (NPEs) was increased in the system and only one alternative analyzed meets pulp quality requirements. / Historicamente a indústria de celulose e papel tem sido considerada uma das maiores consumidoras de recursos naturais. O volume de água consumido pelo setor alcança em média valores de 25 a 100 m3 por tonelada de polpa celulósica produzida. Dentre os estágios que compõem o processo kraft, a planta de branqueamento constitui a maior fonte de geração de efluentes líquidos. Impactos significativos através da redução de geração de efluentes, com fechamento parcial ou total do circuito, trazem economia no consumo de água fresca e benefícios ambientais. A proposta deste trabalho é avaliar a viabilidade da redução do consumo de água fresca no processo de branqueamento, através da recirculação de filtrado no circuito. A partir das condições atuais do processo de fabricação de celulose da indústria Lwarcel Celulose Ltda, que apresenta geração total de efluente de 22 m3/tsa, analisou-se dois graus de fechamento, geração de 19,5 e 17,5 m3/tsa. Com base nestas condições verificou-se a qualidade do produto final, concentração e influencia dos ENPs no circuito, consumo dos insumos de branqueamento e concentração do efluente gerado. Os resultados obtidos apontam que à medida que o circuito de águas foi fechado, aumentou-se a concentração dos elementos não processáveis no sistema e que apenas uma das alternativas avaliadas satisfaz os requisitos de qualidade.

Title: Platonic and Archimedean solids and their properties in teaching of mathematics at secondary schools Author: Eva Dohnalová Department: Department of Didactics of Mathematics Supervisor: doc. RNDr. Jarmila Robová, CSc. Abstract: This work is an extension of my bachelor work and it is intended for all people interested in regular and semiregular polyhedra geometry. It is a comprehensive text which summarizes brief history, description and classification of regular and semiregular polyhedra. The work contains proofs of Descartes' and Euler's theorems and proofs about number of regular and semiregular polyhedra. It can be also used as a didactic aid in the instruction of regular and semiregular solids at secondary schools. This text is supplemented by illustrative pictures made in GeoGebra and Cabri3D. Keywords: Regular polyhedra, platonic solids, Platon, semiregular polyhedra, Archimedean solids, Archimedes, dulaism, Descartes' theorem, Euler's theorem.

Diploma thesis is focused on chemical characteristics of nine selected sweet cherry varieties in nine parameters. Total and soluble solids were analyzed with these results 13.07–16.58 % for total and 14.67–19.50 °Brix for soluble solids, ash content 0,31–0,39 %, titratable acidity 5.44–9.91 g of malic acid per 1 kg of fresh cherries and formol number 14.45–23.73 ml of 0.1 M NaOH per 100 g of cherries. Then there were analyzed crude proteins content calculated from total nitrogen content determined by Kjeldahl method with results 0.41–0.68 % of crude proteins. Molecular absorption UV/VIS spectrophotometry was used for determination of total phenolic substances 0.30–0.89 g of gallic acid per 1 kg of cherries and total content of anthocyanins 128–848 mg of cyanidine-3-glucoside in 1 kg of cherries. Saccharides were determined by high performance liquid chromatography (HPLC) with ELSD detector. Content of glucose was 45.45–59.49 g/kg and fructose 46.88–60.01 g/kg. All results are compiled using tables and graphs and discussed. Experimental part of the thesis also describes principles and procedures of every analysis, so it can be reproduced. In theoretical part there is described botanical characteristic of cherry tree (Prunus avium L.), active substances contained in its fruits and their use in food industry. At the end of the theoretical part there is described instrumentation of high-performance liquid chromatography.

Master of Science / Department of Chemical Engineering / James H. Edgar / Pure boron exists in two main polymorphs, the common β-rhombohedral boron and the relatively rare α-rhombohedral boron. α-rhombohedral boron (α-B) possesses several extraordinary properties: self-healing from radiation damage and a high hole mobility. In addition, the [superscript]10B isotope has a large thermal neutron capture cross section. Such properties make it an excellent candidate for novel electronic device, such as direct energy conversion devices (alphacells and betacells) and neutron detectors. However, research on the properties and applications of α-B has been limited due to the difficulty to produce high quality α-B crystals of significant size. The preparation of α-rhombohedral boron is challenging for several reasons: first, α-rhombohedral boron has a low thermodynamic stability; it is only stable below 1100°C, at higher temperature β-rhombohedral boron is the stable polymorph. In addition, at elevated temperatures, boron is highly reactive, which make it is difficult to produce pure boron crystals. The primary goal of this research was to produce high quality α-B crystals of significant size. The main focus of this study was to explore the feasibility of producing α-B from a copper flux. Copper is a promising solvent for α-B crystal growth: the eutectic temperature of copper-boron is low, 996°C, and the phase diagram of copper-boron is relatively simple, and there are not many intermediate boride-copper compounds. In addition, copper is easily removed from crystals by etching with concentrated nitric acid. Last but not least, copper is less expensive than other metal solvents such as platinum. Boron crystal growth from a platinum solvent and vapor-liquid-solid growth by chemical vapor deposition were also performed for comparison. A series of crystals were grown over a range of initial boron concentrations (9.9 to 27.7 mole %) and cooling rates. Small irregular-shaped black crystals (>100μm) and well-faceted red crystals in various shapes, as large as 500 microns were produced. The crystals were characterized by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction analysis, and Raman spectroscopy. The correlation between experiment results and experimental parameters (source materials, the purity of growth atmosphere, and crucible materials, etc.) are reported. Suggestions about further investigation for α-B crystal growth are proposed.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 1997. / A computer programme for the simulation of dilute phase pneumatic conveying of solids is presented. This includes positive pressure and vacuum pneumatic conveying. The characteristic conveying parameters such as the conveying absolute pressure, conveying air density, interstitial and average air velocity, particle velocity and voidage are calculated by integrating five differential equations that govern two-phase flow. The two-phase flow is approximated as one-dimensional along the pipe axis. Density and acceleration effects are accounted for. The integration is carried out by means of the Runge-Kutta-Fehlberg method yielding conveying parameter traces along the length ofthe pipeline. A new method is presented for the determination of the solids friction coefficient from the solids motion equation. This allows for a more accurate determination of the solids velocity in the pipeline when compared to currently used methods. The computer model results are compared to experimental results for cement and ice conveying yielding good correlation for the main output parameters. The theory for the scaling and calculation of Roots blower performance characteristics is presented. This is implemented in a Roots blower selection programme as an integral part of determining the prime air mover for the design of a pneumatic conveyor. The aim of providing a fast, user-friendly interface in terms of pipeline geometry input, simulation and data visualisation has been achieved by using the advantages of object orientated programming and the visual user interface of the DELPHI programming language.

This study focused on determining the groundwater flow paths in the crystalline subsurface rocks of the Bulawayo metropolitan, Zimbabwe, through analysing the discontinuities of the electrical properties of the ground, as well as in the magnetic field of the underlying rocks. Further, borehole water quality was analysed by measuring and mapping several chemical parameters, specifically TDS, salinity and the electrical conductivity. The electrical and magnetic anomalies were measured at two field sites within the Bulawayo province, the Harry Allen Golf Course and the Barbour Fields dumpsite, while 120 boreholes were sampled for water quality in a large part the province. Two magnetometers were used to measure the magnetic field and the time and location of the measurements, which resulted, after processing in SURFER, into the magnetic field map of these areas. This was used, in conjunction with the geologic map of the Bulawayo province, in order to determine useful locations for the electrical resistivity surveys. These included electrical resistivity tomography and vertical electrical sounding and were performed with an earth resistivity/induced polarization (IP) meter in order to measure the electrical resistivity of the ground. Inverse modelling was used in the RES2DINV software program to produce the topographic image of resistivity. The results for the borehole sampling showed that the maps for the three chemical parameters were very similar, with the western and northern parts of the mapped area displaying higher concentration values. The results of the electrical resistivity surveying showed probable areas of groundwater flow with its relationship to electric conductivity.

Pharmaceutical solids tend to exist in different physical forms termed as polymorphs. Issues about pharmaceutical systems are mainly concerned with the active ingredient's physico-chemical stability and bioavailability. The main aim of this study is to investigate the non-bonded interactions in pharmaceutical solids that govern the physical pharmaceutics performance of such materials and through the use of structural techniques and correlation of these results with crystal structural database to establish the presence of physical motifs in selected systems. Structural motifs were identified by the use of single crystal and crystal packing analysis on diverse range of pharma-relevant materials including chalcones, cryptolepines, biguanides and xanthines. These selected systems were validated using functional group and molecular analysis and correlating them to the Cambridge Structural Database. Crystallization studies are done on these selected systems as well as exploiting those using synthetic analogues. A total of 51 crystal structures were investigated including 16 new structure determinations. Addition synthesis of new xanthines to investigate novel intermolecular patterns was also undertaken. The understanding and exploitation of intermolecular interactions involving hydrogen bonds and coordination complexation during packing can be used in the design and synthesis of solid state molecular structures with desired physical and chemical properties.

Designing materials for fusion applications is a very challenging problem, requiring detailed understanding of the behaviour of materials under the kinds of extreme conditions expected in a fusion environment. During the lifetime of fusion-reactor components, materials will be subjected to high levels of neutron irradiation, but must still perform effectively at high operating temperatures and under significant loading conditions. Body-centred cubic (bcc) transition metals are some of the most promising candidates for structural materials in fusion because of their relatively high density, which allows for effective neutron-shielding with the minimum volume and mass of material. In this work we perform atomistic simulations on two of the most important of these, Fe and W. In this thesis we describe atomic-scale simulations of defects found in bcc systems. In part I we consider the vacancy and interstitial loop defects that are produced and accumulated as a result of irradiation-induced displacement cascades. We show that vacancy dislocation loops have a critical size below which they are highly unstable relative to planar void defects, and thus offer an explanation as to why they are so rarely seen in TEM observations of irradiated bcc metals. Additionally, we compare the diffusion rates of these vacancy loops to their interstitial counterparts and find that, while interstitial loops are more mobile, the difference in mobility is not as significant as might have been expected. In part II we study screw dislocations, which, as the rate limiting carriers of plastic deformation, are significantly responsible for the strength of materials. We present results from large-scale finite temperature molecular dynamics simulations of screw dislocations under stress and observe the thermally-activated kink-pair formation regime at low stress, which appears to be superseded by a frictional regime at higher stresses. The mobility functions fitted to the results are vital components in simulations of dislocation networks and other large-scale phenomena. Lastly, we develop a multi-string Frenkel-Kontorova model that allows us to study the core structure of screw dislocations. Subtle changes in the form of the interaction laws used in this model demonstrate the difference between the non-degenerate and degenerate core structures. We provide simple criteria to guarantee the correct structure when developing interatomic potentials for bcc metals.

This thesis is a theoretical study of configurational disorder in icosahedral boron-rich solids, in particular boron carbide, including also the development of a methodological framework for treating configurational disorder in such materials, namely superatom-special quasirandom structure (SA-SQS). In terms of its practical implementations, the SA-SQS method is demonstrated to be capable of efficiently modeling configurational disorder in icosahedral boron-rich solids, whiles the thermodynamic stability as well as the properties of the configurationally disordered icosahedral boron-rich solids, modeled from the SA-SQS method, can be directly investigated, using the density functional theory (DFT). In case of boron carbide, especially B4C and B13C2 compositions, the SA-SQS method is used for modeling configurational disorder, arising from a high concentration of low-energy B/C substitutional defects. The results, obtained from the DFT-based calculations, demonstrate that configurational disorder of B and C atoms in boron carbide is not only thermodynamically favored at high temperature, but it also plays an important role in altering the properties of boron carbide − for example, restoration of higher rhombohedral symmetry of B4C, a metal-to-nonmetal transition and a drastic increase in the elastic moduli of B13C2. The configurational disorder can also explain large discrepancies, regarding the proper- ties of boron carbide, between experiments and previous theoretical calculations, having been a long standing controversial issue in the field of icosahedral boron- rich solids, as the calculated properties of the disordered boron carbides are found to be in qualitatively good agreement with those, observed in experiments. In order to investigate the configurational evolution of B4C as a function of temperature, beyond the SA-SQS level, a brute-force cluster-expansion method in combination with Monte Carlo simulations is implemented. The results demonstrate that configurational disorder in B4C indeed essentially takes place within the icosahedra in a way that justifies the focus on lowenergy defect patterns of the superatom picture. The investigation of the thermodynamic stability of icosahedral carbon-rich boron carbides beyond the believed solubility limit of carbon (20 at.% C) demonstrates that, apart from B4C generally addressed in the literature, B2.5C represented by B10Cp2(CC) is predicted to be thermodynamically stable with respect to B4C as well as pure boron and carbon under high pressure, ranging between 40 and 67 GPa, and also at elevated temperature. B2.5C is expected to be metastable at ambient pressure, as indicated by its dynamical and mechanical stabilities at 0 GPa. A possible synthesis route of B2.5C and a fingerprint for its characterization from the simulations of x-ray powder diffraction pattern are suggested. Besides modeling configurational disorder in boron carbide, the SA-SQS method also opens up for theoretical studies of new alloys between different icosahedral boron-rich solids − for example, (B6O)1−x(B13C2)x and B12(As1−xPx)2. As for the pseudo-binary (B6O)1−x(B13C2)x alloy, it is predicted to display a miscibility gap resulting in B6O-rich and either ordered or disordered B13C2-rich domains for intermediate global compositions at all temperatures up to melting points of the materials. However, some intermixing of B6O and B13C2 to form solid solutions is also predicted at high temperature. A noticeable mutual solubility of icosahedral B12As2 and B12P2 in each other to form B12(As1−xPx)2 disordered alloy is predicted even at room temperature, and a complete closure of a pseudo-binary miscibility gap is achieved at around 900 K. Apart from B12(As1−xPx)2, the thermodynamic stability of other compounds and alloys in the ternary B-As-P system is also investigated. For the binary B-As system, zincblende BAs is found to be thermodynamically unstable with respect to icosahedral B12As2 and gray arsenic at 0 K and increasingly so at higher temperature, indicating that BAs may merely exist as a metastable phase. This is in contrast to the binary B-P system, in which zinc-blende BP and icosahedral B12P2 are both predicted to be stable. Owing to the instability of BAs with respect to B12As2 and gray arsenic, only a tiny amount of BAs is predicted to be able to dissolve in BP to form BAs1−xPx disordered alloy at elevated temperature. For example, less than 5% BAs can dissolve in BP at 1000 K. As for the binary As-P system, As1−xPx disordered alloys are predicted at elevated temperature − for example, a disordered solid solution of up to ∼75% As in black phosphorus as well as a small solubility of ∼1% P in gray arsenic at 750 K, together with the presence of miscibility gaps. The thermodynamic stability of three different compositions of α-rhombohedral boron-like boron subnitride, having been proposed so far in the literature, is investigated. Those are, B6N, B13N2, and B38N6, represented respectively by B12(N-N), B12(NBN), and [B12(N-N)]0.33[B12(NBN)]0.67. It is found that, out of these sub- nitrides, only B38N6 is thermodynamically stable from 0 GPa up to ∼7.5 GPa, depending on the temperature, and is thus concluded as a stable composition of α-rhombohedral boron-like boron subnitride.