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Timlett, Rose. "Recycling in high and medium density housing." Thesis, University of Southampton, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543417.
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Plosz, Laura Marlayne. "Multiplicity through abstraction, a design for medium-density housing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0025/MQ50309.pdf.
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Eugênio, Rafael Augusto Pinholati [UNESP]. "Painéis de medium density fiberboard produzidos com adesivo alternativo." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/145030.
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O trabalho consistiu na produção de painéis de MDF (Medium Density Fiberboard) em escala laboratorial utilizando o adesivo PVA (Poliacetato de Vinila), variando suas concentrações e realizando misturas com a resina comumente empregada neste processo, o adesivo a base de uréia-fomaldeído, onde foi avaliado além das características físicas e mecânicas dos painéis produzidos, também teve o intuito de verificar o desprendimento de formaldeído para o ambiente quando aplicado juntamente com a resina uréia-fomaldeído, e a avaliação dos perfis de densidades dos traços. As amostras foram confeccionadas com fibra de eucalipto, onde as dosagens do adesivo PVA seguiram as seguintes proporções: 30%, 50% e 70%, e para efeito de comparação com as amostras produzidas com a mistura de PVA foram fabricadas provas em branco com 100% uréia-formaldeído. No total foram produzidas 16 amostras, quatro painéis de cada traço, e retirados os corpos de prova que posteriormente foram avaliados conforme a NBR 15316-2:2015 para as condições secas. Todos os insumos foram fornecidos pelo fabricante de painéis Duratex SA, e os testes foram realizados nos laboratórios da empresa. O adesivo PVA mostrou-se bastante favorável, apresentando grande compatibilidade com os demais componentes da formulação, apresentando potencial para fabricação de MDF. Diversos traços conseguiram atender os requisitos da norma, com destaque para módulo de ruptura (MOR), módulo de elasticidade (MOE), obtidos atraves do ensaio de flexão estática, e o teor de umidade. Houve também uma discreta redução na emissão de formol em dois traços (T3 e T4), e na avaliação dos perfis de densidade foi constatado que a formulação dos traços não impactou nas densidades médias da espessura dos painéis.
The work consisted in the production of MDF (Medium Density Fiberboard) in laboratory scale using PVA adhesive (Polyacetate Vinyl Chloride), varying their concentrations and performing mixtures with commonly used resin in this process, the adhesive base of ureafomaldehyde, which was evaluated in addition to the physical and mechanical characteristics of the panels produced, also aimed to check the formaldehyde release to the environment when applied together with resin urea-fomaldehyde, and evaluation of the densities of the features profiles. The samples were made from eucalyptus fibers where PVA adhesive doses followed the following proportions: 30%, 50% and 70%, and for the purpose of comparison with the samples produced with the mixture of PVA blank tests were made with 100 % ureaformaldehyde. In total, we produced 16 samples, four panels of each stroke, and removed the specimens which were then evaluated according to NBR 15316-2: 2015 for dry conditions. All inputs were provided by the panel manufacturer Duratex SA, and the tests were performed in the company's laboratories. PVA adhesive proved to be very favorable, with high compatibility with the other components of the formulation, with potential for the production of MDF. Many features were able to meet the standard requirements, particularly modulus of rupture (MOR), modulus of elasticity (MOE), obtained through the bending, and moisture content test. There was also a slight reduction in formaldehyde emissions by two dashes (T3 and T4), and evaluation of density profiles was found that the formulation of the traits did not affect the average thickness of the thickness of the panels.
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Eugênio, Rafael Augusto Pinholati. "Painéis de medium density fiberboard produzidos com adesivo alternativo /." Bauru, 2016. http://hdl.handle.net/11449/145030.
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Orientador: Ivaldo De Domenico ValarelliBanca: Rosane Aparecida G. Basttistelle
Banca: Alexandre Jorge Duarte Souza
Resumo: O trabalho consistiu na produção de painéis de MDF (Medium Density Fiberboard) em escala laboratorial utilizando o adesivo PVA (Poliacetato de Vinila), variando suas concentrações e realizando misturas com a resina comumente empregada neste processo, o adesivo a base de uréia-fomaldeído, onde foi avaliado além das características físicas e mecânicas dos painéis produzidos, também teve o intuito de verificar o desprendimento de formaldeído para o ambiente quando aplicado juntamente com a resina uréia-fomaldeído, e a avaliação dos perfis de densidades dos traços. As amostras foram confeccionadas com fibra de eucalipto, onde as dosagens do adesivo PVA seguiram as seguintes proporções: 30%, 50% e 70%, e para efeito de comparação com as amostras produzidas com a mistura de PVA foram fabricadas provas em branco com 100% uréia-formaldeído. No total foram produzidas 16 amostras, quatro painéis de cada traço, e retirados os corpos de prova que posteriormente foram avaliados conforme a NBR 15316-2:2015 para as condições secas. Todos os insumos foram fornecidos pelo fabricante de painéis Duratex SA, e os testes foram realizados nos laboratórios da empresa. O adesivo PVA mostrou-se bastante favorável, apresentando grande compatibilidade com os demais componentes da formulação, apresentando potencial para fabricação de MDF. Diversos traços conseguiram atender os requisitos da norma, com destaque para módulo de ruptura (MOR), módulo de elasticidade (MOE), obtidos atraves do ensaio de flexã... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The work consisted in the production of MDF (Medium Density Fiberboard) in laboratory seade using PVA adhesive (Polyacetate Chloride), varying their concentration and perfomring mixtures with commonly used resin in this process the adhesive base of urea-fomaldehyde, which was evaluated in addition to the physical and mechanical characteristics of the panels produced, also aimed to check the formaldehyde release to the environment when applied together with resin urea-formaldehyde, and evaluation of the desnsities of the features profiles. The samples were made from eucalyptus fibers where PVA adhesive doses followed proportions: 30%, 50% and 70%, and for the purpose of comparison with the samples produced with the samples produced with the mixture of PVA blank tests were made with 100% urea-formaldehyde. In total, we produced 16 samples, four panels of each stroke, and removed the speciments which then evaluated according to NBR 15316-2:2015 for dry conditions. All inputs were provided by the panel manufacturer Duratex SA, and the tests were performed in the company's laboratories. PVA adhesive proved to be very favorable, with high compatibility with the other components of the formulation, with potential for the production of MDF. Many features were able to meet the standard requirements, particularly modulus of rupture (MOR), modulus of elasticity (MOE), obtained through the bending, and moisture content test. There was also a slight reduction in formaldehyde emissions by two dashes (T3 and T4), and evaluation of density profiles was found that the formulation of the traits did not affect the average thickness of the thickness of the panels
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Ezzat, Showaib A. "Fatigue acceleration of crack growth in medium density polyethylene." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1057004988.
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Alves, Thomas. "Managing medium density housing development a municipal case study /." Swinburne Research Bank, 2006. http://hdl.handle.net/1959.3/22539.
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Thesis (PhD) - Institute for Social Research, Swinburne University of Technology, 2006.Thesis submitted in fulfillment of the requirements of the degree of Doctor of Philosophy, Institute for Social Research, Swinburne University of Technology, 2006. Typescript. 'December 2006'. Includes bibliographical references (p. 303-326).
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Chapman, Kelvin M. "A study of two aspects of medium density fibreboard manufacture." Thesis, University of Canterbury. Chemical and Process Engineering, 2004. http://hdl.handle.net/10092/7188.
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This thesis covers two aspects of MDF panel manufacture,
In Part A of the thesis the development and application of a plant - based model of the blowline resin blending process used in the manufacture of Medium Density Fibreboard (MDF) is described, Experience quoted in the literature, operating experience in plants and data from specific plant trials have provided a number of insights into the process, but it was not until a calculation of the blowline steam flow became available that these disparate observations could be integrated into the comprehensive model of the blowline blending process that is described in this thesis,
The steam flow in the blowline is calculated from a combined mass - energy balance over the refiner, allowing the steam velocity profile in the blowline to be established, In addition to the perspective that this data provides in understanding the various observations of the blowline blending process, it also shows a linkage between blowllne velocities and nozzle atomisation that prevents the use of high pressure atomising nozzles to create small resin droplets unless blowline velocities are high. It is concluded that this relationship is largely responsible for the higher resin contents that blowline resin addition requires when compared with MDF made using the dry blending process that is used for other wood - based composites.
The refiner mass - energy balance shows that blowline conditions are sensitive to the refiner conditions, with relatively small changes in some parameters used to control the refiner operation changing the blowline steam flow significantly. This raises the possibility that changes in blowline conditions contribute to significant variability in the bonded fibre network that makes up MDF,
Once the steam flow is known for a particular case, the blowline design can be optimised to provide the blending conditions that have been found to give a good blending result. This has been now been done in 25 MDF plants around the world; in 24 cases the blowline diameter was greater than the optimum for good blending. In the remaining case the diameter had been reduced, to the point where the choke flow limit was exceeded, leading to a fibre buildup on the dryer wall.
The significance of resin droplet size, in terms of its effect on the strength properties of the panel and on the outcome of the blending process is discussed. The relationship between the mass of resin in each droplet and the mass of the fibre is significant in the blending process, particularly in the formation of resin spots. There are indications both from panel studies and from the resin performance in blowlines that have been optimised, that resin droplets should be smaller rather than larger.
Resin atomisation, both in pressure and steam atomised nozzles and through interaction with the blowline steam flow is examined. This results in a wide range of resin droplet sizes, with the smallest from an effective atomising nozzle and the largest created by the interaction of the resin stream with a low steam velocity in the blowline. This wide range of conditions explains much of the variability in the blending outcome, ranging from good resin efficiency where resin droplets are small and poor resin efficiency where resin droplets are larger. The development of a steam - atomised resin injection nozzle is described. The nozzle is in commercial production with a number of units in service. Good resin efficiencies have been achieved, while the design has been successful in overcoming resin blocking problems that have occurred with other nozzle types.
The blowline blending model has proved to be both robust and reliable. It was originally developed to reduce resin usage, with reductions of up to 25% of resin previously added having been achieved. In addition the model also provides solutions to a number of problems which have been shown to originate in the blowline.
This thesis develops and extends the concepts used in the model to validate the approach and to provide insights into its further development.
In Part B of the thesis the influence of temperature, moisture and fibre type on the stress response of a fibre mat to an applied strain was investigated to determine the impact of these variables on the development of the Vertical Density Profile (VDP) in MDF panels.
There are a number of models of the in the literature that predict the development of VDP from the condition of the material in the press and the press conditions. While these models, developed for particleboard, claim to be sufficiently general to be extended to cover the case of MDF, there are features of the MDF profile that suggest that this might not be the case. This investigation was set up to determine the stress - strain response of MDF fibre under the conditions encountered in the hot pressing operation.
A small circular press was designed so that it could be mounted in a compression testing machine, allowing the stress strain data to be recorded. The press was constructed so that heated and humidified air could be passed through the mat so that uniform temperature and moisture conditions could be established through the mat prior to the stress - strain measurements being made. The press was then closed to determine the stress - strain response of the fibre. After the press was closed it was held in that position and the relaxation response of the fibre mat measured under conditions where the compliance of the press imposed a small continuing strain on the mat as the relaxation of the fibre reduced its compressive resistance.
The fibre response at moisture levels of 0% - 20% and at temperatures up to 100°C was measured although limitations of the conditioning limited the moisture content that could be reached at the higher temperature ranges. Two fibre types, prepared from high and low density P. Radiata wood, showed a very similar stress – strain response.
The density stress response for the fibre mat appears to follow that for a foam compression model where the resistance to compression at constant temperature and moisture is proportional to the square of the density ratio. An extension to the cellular foam theory to the situation of a discrete fibre mat is proposed.
The temperature and moisture effect on the compressive resistance of the fibre mat appears to follow established relationships for solid wood, although the inability to reach the high temperature - high moisture condition excludes this important area from the analysis.
A modified stress relaxation response is characterised by an increase in density that, at constant moisture content, appears to be independent of the density of the mat, over the range encountered in the development of the density profile. The moisture effect on the stress relaxation response appears to be more significant than that due to temperature.
It is concluded that temperature and moisture content gradients established early in the press are the most significant factors in determining the vertical density profile through the MDF panel. The squared relationship with density implies that these gradients are particularly important in the generation of the high density of the faces of the VDP. The stress relaxation effect provides a uniform increase in density through the mat, modified only by a moisture response which increases this effect where moisture contents are high.
The data provide insights into the relative effects of temperature, moisture and density as these change in the pressing of MDF fibre, in a form that can be incorporated in a model of the pressing process and also used by MDF press operators to aid in their understanding of the processes that lead to generation of the VDP in commercial MDF operations.
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Palmer, Simon J. "Stabilisation of medium density polyethylene gas pipe in service applications." Thesis, Manchester Metropolitan University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329807.
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Kocabas, Zeynep. "Forecasting Of Ionospheric Electron Density Trough For Characterization Of Aerospace Medium." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610445/index.pdf.
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Modeling the ionosphere, where the effects of solar dynamo becomes more effective to space based and ground borne activities, has an undeniable importance for telecommunication and navigation purposes. Mid-latitude electron density trough is an interesting phenomenon in characterizing the behavior of the ionosphere, especially during disturbed conditions. Modeling the mid-latitude electron density trough is a very popular research subject which has been studied by several researchers until now. In this work, an operational technique has been developed for a probabilistic space weather forecast using fuzzy modeling and computer based detection of trough in two steps. First step is to detect the appropriate geomagnetical conditions for trough formation, depending on the values of 3-h planetary K index (Kp), magnetic season, latitude and local time, by using fuzzy modeling technique. Once the suitable geomagnetic conditions are detected, second step is to find the lower latitude position (LLP) and minimum position (MP) of the observed trough being two main identifiers of the mid-latitude electron density trough.
A number of case studies were performed on ARIEL 4 satellite data, composed of different geomagnetic, annual and diurnal characteristics. The results obtained from fuzzy modeling show that the model is able to detect the appropriate conditions for trough occurrence and the trough shape was effectively identified for each selected case by using the predefined descriptions of mid-latitude electron density trough. The overall results are observed to be promising.
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Du, Wei 1962. "A study of medium-rise high-density housing : Beijing, 1979-1990." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22542.
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In China, huge population and limited arable land resources constitute one of the basic contradictions in urban mass housing design. As a stereotype, medium-rise apartment buildings were constructed to attain high densities all over the country during the 1980s. The extensive use of the housing typologies caused problems in many aspects. This reflects the poverty of architectural solutions and the consequences of the socio-economic systems of the country.Focusing on the aspects of single building design and site planning, this thesis analyses the methods to reach high building densities in medium-rise mass housing design in Beijing from 1979 to 1990. The study is conducted through the review of the socio-economic issues and the introduction of mass housing design of the country. It intends to see the interrelationships between ways to attain high building densities and the socio-economic backgrounds.
The research indicates that methods to reach high building densities are many. Ways used in Beijing during 1980s were based on the socio-economic system at the time being. These ways are not appropriate in terms of the unique urban context of the city and could be thus replaced by others.
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Dettmer, Jörn. "Properties comparison of North American manufactured particleboard and medium density fiberboard." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45575.
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A survey of Canadian and US particleboard (PB) and medium density fiberboard (MDF) manufacturers was performed to identify potential candidates for the mechanical and physical properties comparison study. Sixty-three plants across Canada and the United States were contacted and 19 plants participated in the survey. In order to obtain and compare data on mechanical and physical properties of boards from PB and MDF manufacturers, samples were collected from 10 different manufacturing facilities across Canada and the United States (5 PB and 5 MDF). The performed tests included internal bond (IB), bending and elastic moduli (MOR/MOE), thickness swell (TS), linear expansion (LE), vertical density profile (VDP), and face and edge screw withdrawal resistance (SWR). Each manufacturing facility provided 5 full-sized (2440 by 1220 mm) panels that were tested according to North American standards. For particleboard, 4 out of 5 press lines exceeded the American National Standards Institute (ANSI) A208.1-2009 recommendation for IB. Only one of the tested particleboard sets reached the recommended ANSI standard for MOR. Results for the edge SWR showed that none of the tested particleboard manufacturers reached the ANSI recommended value. For MDF, all but one press line exceeded the ANSI standard A208.2-2009 recommended minimum value for MOE. The results for the modulus of rupture for MDF showed two manufacturers exceeding the recommended value, and three failing to meet the recommended value.
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Van, Velthoven P. J. F. "Medium scale irregularities in the ionospheric electron content." Utrecht : Drukkerij Elinkwijk, 1990. http://catalog.hathitrust.org/api/volumes/oclc/22643184.html.
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O'Dwyer, Lisel Alice. "Medium density housing in Adelaide : a study of market led housing provision /." Title page, contents and abstract only, 1992. http://web4.library.adelaide.edu.au/theses/09AR/09aro27.pdf.
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Vujanovic, Gojko. "A theoretical model for the in-medium spectral density of vector mesons /." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111618.
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We study the hadronic phase of Quantum Chromodynamics within a formalism that uses strongly interacting resonances in the Regge theory approach. Our aim is to investigate the properties of the medium created in a relativistic nucleus-nucleus collision, using the electromagnetic decays of vector mesons as probe. To do so, we first layout the foundations of Regge theory, which is then used to calculate the in-medium properties of vector mesons. This methodology will be used to calculate for the first time the properties of the &phis; meson in a hadronic medium. The properties are contained within the imaginary part of the propagator (IMPP). Since it is related to electromagnetic decay via vector meson dominance, the IMPP is a probe of strongly interacting hadron gas created in the collision.
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Zerizer, Abdellatif. "Contribution à l'étude de l'usinabilité du M. D. F. (Medium density fiberboard)." Nancy 1, 1991. http://www.theses.fr/1991NAN10335.
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Un dispositif d'usinage permettant la combinaison de plusieurs paramètres d'action (vitesse d'avance, fréquence de rotation et profondeur de passe) a été mis en place à partir d'une toupie expérimentale adaptée à cet effet. Un plan d'expérience qui délimite à partir des gammes choisies, l'influence de l'ensemble des variables de coupe a été mis en place. Les essais d'usinage pour chacune des combinaisons retenues permettent des relevés d'efforts, de puissances et de forme de copeaux. La suite du travail est consacrée à la caractérisation géométrique ou topographique de l'ensemble de ces surfaces usinées au moyen de diverses méthodes (palpage mécanique, tests viso-tactile et vision artificielle). Celles-ci sont suivies d'essais de mouillabilité de surface liées aux problèmes de revêtement par produits de finition et de comportement mécanique des joints collés par un critère GLC : taux de restitution d'énergie. Parmi l'ensemble des données obtenues, nous avons retenu les résultats les plus significatifs qui aboutissent aux paramètres de coupe optimum. On constate tout d'abord que les trois critères liés à l'emploi : collage (glc), finition (o), aspect (ra) sont liés. Dans l'état actuel de nos travaux, le plus représentatif est GLC qui prend en compte l'ensemble de la topographie de la surface. Cette qualité des surfaces obtenues est liée aux conditions de coupe représentée par la variable EM. Epaisseur moyenne du copeau. Par ailleurs, une surface plus rugueuse obtenue suite à des copeaux épais, donne une énergie de collage plus forte. Cette énergie est basée sur le phénomène d'une plus grande mouillabilité (angle de contact plus faible) et donc une meilleure adhésion. Cependant la création de ce type de surface (copeau épais) nécessite avec elle, une puissance de coupe importante qu'il reste à optimiser.
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V, Tromsa Ye. "FEATURES OF ARCHITECTURAL-PLANNING ORGANIZATION OF MEDIUM-RISE HIGH-DENSITY RESIDENTIAL HOUSING." Thesis, ПОЛІТ.Сучасні проблеми науки.Гуманітарні науки:тези доповідей XVII Міжнародної науково-практичної конференції молодих учених і студентів:[y 2-x т.].Т.2(м.Київ,4-7 квітня 2017 р.)/[ред.кол.:В.М.Ісаєнко та ін.]; Національний авіаційний університет.-К.:НАУ,2017.-374 с, 2017. http://er.nau.edu.ua/handle/NAU/27739.
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Constant population growth creates demand for land resources including residential space. Population growth requires certain density of city environment and architecture with the correspondent qualities. Under the conditions of high density, architectural forms may be the most viable models of future architecture in general and residential buildings in particular.
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Theado, John. "An Optimal Medium-Strength Regularity Algorithm for 3-uniform Hypergraphs." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7969.
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Szemere´di’s Regularity Lemma [32, 33] is an important tool in combinatorics, with numerous appli- cations in combinatorial number theory, discrete geometry, extremal graph theory, and theoretical computer science.
The Regularity Lemma hinges on the following concepts. Let G = (V, E) be a graph and let ∅ /= X, Y ⊂ V be a pair of disjoint vertex subsets. We define the density of the pair (X, Y ) by dG(X, Y ) = |E[X, Y ]|/(|X||Y |) where E[X, Y ] denotes the set of edges {x, y} ∈ E with x ∈ X and y ∈ Y . We say the pair (X, Y ) is ε-regular if all subsets XI ⊆ X and Y I ⊆ Y satisfying |XI| > ε|X| and |Y I| > ε|Y | also satisfy |dG(XI, Y I) − dG(X, Y )| < ε.
The Regularity Lemma states that, for all ε > 0, all large n-vertex graphs G = (V, E) admit a partition V = V1 ∪ · · · ∪ Vt, where t = t(ε) depends on ε but not on n, so that all but εt2 pairs (Vi, Vj), 1 ≤ i < j ≤ t, are ε-regular. While Szemere´di’s original proof demonstrates the existence of such a partition, it gave no method for (efficiently) constructing such partitions. Alon, Duke, Lefmann, Ro¨dl, and Yuster [1, 2] showed that such partitions can be constructed in time O(M (n)), where M (n) is the time needed to multiply two n × n {0, 1}-matrices over the integers. Kohayakawa, Ro¨dl, and Thoma [17, 18] improved this time to O(n2).
The Regularity Lemma can be extended to k-uniform hypergraphs, as can algorithmic for- mulations thereof. The most straightforward of these extends the concepts above to k-uniform hypergraphs H = (V, E) in a nearly verbatim way. Let ∅ /= X1, . . . , Xk ⊂ V be pairwise disjoint subsets, and let E[X1, . . . , Xk] denote the set of k-tuples {x1, . . . , xk} ∈ E satisfying x1 ∈ X1, . . . , xk ∈ Xk. We define the density of (X1, . . . , Xk) as
dH(X1, . . . , Xk) = |E[X1, . . . , Xk]| / |X1| · · · |Xk|.
We say that (X1, . . . , Xk) is ε-regular if all subsets XiI ⊆ Xi, 1 ≤ i ≤ k, satisfying |XiI| > ε|Xi| also satisfy
|dH (X1I , . . . , XkI ) − dH (X1, . . . , Xk)| < ε.
With these concepts, Szemeredi’s original proof can be applied to give that, for all integers k ≥ 2 and for all ε > 0, all n-vertex k-uniform hypergraphs H = (V, E) admit a partition V = V1 ∪· · ∪ Vt, where t = t(k, ε) is independent of n, so that all but εtk many k-tuples (Vi1 , . . . , Vik) are ε-regular, where 1 ≤ i1 < · · · < ik ≤ t. Czygrinow and Ro¨dl [4] gave an algorithm for such a regularity lemma, which in the context above, runs in time O(n2k−1 log5 n).
In this dissertation, we consider regularity lemmas for 3-uniform hypergraphs. In this setting, our first main result improves the algorithm of Czygrinow and Ro¨dl to run in time O(n3), which is optimal in its order of magnitude. Our second main result shows that this algorithm gives a stronger notion of regularity than what is described above, where this stronger notion is described in the course of this dissertation. Finally, we discuss some ongoing applications of our constructive regularity lemmas to some classical algorithmic hypergraph problems.
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Muller-Warrens, Marianne. "Towards sustainable building design principles for medium density, middle income housing in Gauteng." Diss., Pretoria : [s.n.], 2001. http://upetd.up.ac.za/thesis/available/etd-08132008-112233.
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Fisher, Susan. "Landscape alternatives for cost savings and resource conservation in medium-density Canadian housing." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69774.
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The grounds of Canadian homes typically consist of trimmed lawns sparsely planted with ornamental trees and shrubs. Despite their low initial cost and immediate impact, conventional landscapes require significant annual capital and physical resources, such as fuel, water, herbicides and fertilizer. However, low-maintenance alternatives exhibit lower consumption rates and annual cost savings. This paper investigates the saving potential of four low-maintenance alternatives when compared to a conventional option through an evaluation of life cycle cost and annual maintenance resource consumption.The five options were simulated using the proposed site and building of a low-rise, multi-residential housing project in Ottawa, where only the planting design varied for each simulation. The four alternatives involved: (1) replacing 70% of lawn areas with woody plants grouped in mulched beds, (2) eliminating turf and including 85% woody plants and a hard surface area of 15%, (3) replacing 70% of the turf area with naturalized woodland plantings and (4) replacing all turf areas with 85% naturalized woodland and tall grass prairie plantings and including a hard surface area of 15%. Only species that are well-adapted to the site conditions were selected for the alternatives. (Abstract shortened by UMI.)
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Walther, Marc. "Variable-Density Flow Processes in Porous Media On Small, Medium and Regional Scales." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-153365.
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Nowadays society strongly depends on its available resources and the long term stability of the surrounding ecosystem. Numerical modelling has become a general standard for evaluating past, current or future system states for a large number of applications supporting decision makers in proper management. In order to ensure the correct representation of the investigated processes and results of a simulation, verification examples (benchmarks), that are based on observation data or analytical solutions, are utilized to evaluate the numerical modelling tool.
In many parts of the world, groundwater is an important resource for freshwater. While it is not only limited in quantity, subsurface water bodies are often in danger of contamination from various natural or anthropogenic sources. Especially in arid regions, marine saltwater intrusion poses a major threat to groundwater aquifers which mostly are the exclusive source of freshwater in these dry climates. In contrast to common numerical groundwater modelling, density-driven flow and mass transport have to be considered as vital processes in the system and in scenario simulations for fresh-saltwater interactions.
In the beginning of this thesis, the capabilities of the modelling tool OpenGeoSys are verified with selected benchmarks to represent the relevant non-linear process coupling. Afterwards, variable-density application and process studies on different scales are presented. Application studies comprehend regional groundwater modelling of a coastal aquifer system extensively used for agricultural irrigation, as well as hydro-geological model development and parametrization. In two process studies, firstly, a novel method to model gelation of a solute in porous media is developed and verified on small scale laboratory observation data, and secondly, investigations of thermohaline double-diffusive Rayleigh regimes on medium scale are carried out.
With the growing world population and, thus, increasing pressure on non-renewable resources, intelligent management strategies intensify demand for potent simulation tools and development of novel methods. In that way, this thesis highlights not only OpenGeoSys’ potential of density-dependent process modelling, but the comprehensive importance of variable-density flow and transport processes connecting, both, avant-garde scientific research, and real-world application challenges.
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Guimarães, Íngrid Luz. "Aproveitamento de resíduo de soja para produção de painéis MDP (Medium Density Particleboard)." Universidade Federal de Goiás, 2017. http://repositorio.bc.ufg.br/tede/handle/tede/7520.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Soybean pre-cleaning residue is found in large quantities in the processing and processing dryers' farms, resulting in serious inconvenience if it is not removed to farther places before the fermentation process begins. Among the residues generated at the time of harvesting and cleaning of the grains are soybean pods, which presents as an alternative lignocellulosic material to be used in the production of Agglomerated panels of the MDP type. The objective of this work was to verify the effect of the use of soybean pods in the production of eucalyptus MDP panels. The panels, with a nominal density of 0.70 g / cm³, were composed of three layers, the thin layers of eucalyptus wood were used in the covers and the core was composed of a mixture of eucalyptus particles and soybean pods. The proportions used of soybean residue particles in relation to those of eucalyptus in the kernels were 0, 25, 50, 75 and 100%. For the glueing of the particles the adhesive urea formaldehyde, in the proportion of 12%, was used for both the covers and the crumb. The pressing cycle had a temperature of 160 ° C for a period of 15 minutes at a pressure of 4MPa. To evaluate the quality of the panels produced, their physical and mechanical properties of apparent density; Compaction ratio; Water absorption and swelling in thickness at 2 and 24 hours of immersion were determinater; Perpendicular traction; Modulus of elasticity and modulus of rupture in the static bending. To meet the requirements of Brazilian standard (NBR 14.810 / 2002), for the properties of swelling in thickness (2h) and modulus of rupture, the maximum amount of soybean recommended for MDP panels is 20%.
O resíduo da pré-limpeza de soja é encontrado em grande quantidade no pátio das indústrias de beneficiamento e dos secadores das fazendas, acarretando sérios transtornos caso não seja removido para locais mais afastados antes que o processo de fermentação se inicie. Dentre os resíduos gerados no momento da colheita e limpeza dos grãos estão às vagens de soja, que se apresenta como um material lignocelulósico alternativo para ser utilizado na produção de painéis aglomerados do tipo MDP. Este trabalho teve como objetivo verificar o efeito da utilização de vagens de soja na produção de painéis MDP de eucalipto. Os painéis, com densidade nominal de 0,70 g/cm³, foram constituídos por três camadas, de modo que nas capas foram utilizadas finas partículas de madeira de eucalipto e o miolo foi composto por uma mistura de partículas de eucalipto e de vagens soja. As proporções utilizadas de partículas de resíduo de soja em relação às de eucalipto no miolo foram de 0, 25, 50, 75 e 100%. Para o encolamento das partículas foi utilizado o adesivo uréia formaldeído, na proporção de 12%, tanto para as capas como para o miolo. O ciclo de prensagem teve temperatura de 160°C, por um período de 15 minutos a uma pressão de 4MPa. Para avaliar a qualidade dos painéis produzidos, foram determinadas suas propriedades físicas e mecânicas de densidade aparente; razão de compactação; absorção de água e inchamento em espessura em 2 e 24 horas de imersão; tração perpendicular; módulo de elasticidade e módulo de ruptura na flexão estática. Para atender as exigências da norma brasileira (NBR 14.810/2002), para as propriedades de inchamento em espessura (2h) e módulo de ruptura, a quantidade máxima de vagem de soja recomendada para painéis MDP é de 20%.
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Gillah, Peter Reuben. "The influence of novel forming techniques on the properties of medium density fibreboard." Thesis, Bucks New University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369910.
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Muto, Ryotaro. "Evidence for in-medium modification of the φ meson at normal nuclear density." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136956.
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Van, Rooyen Petrus Mynhardt. "Is it feasable to increase the medium density fibreboard manufacturing capability in South Africa?" Thesis, Port Elizabeth Technikon, 2004. http://hdl.handle.net/10948/255.
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Medium density fibre (MDF) board is used in various applications in the building-, furniture- and casket industry. The market is shared by solid wood and other flat panels, such as particle board and plywood. The market in South Africa forms part of the global market. Therefore it is possible to import MDF. The demand for MDF is driven by the building industry, the Consumer Price Index (CPI) and the exchange rate. The CPI is an indication of the consumer’s willingness to purchase furniture or to invest in property with subsequent growth in the building industry. The 2002 market in SA is 500 000m3 for particle board and 110 000m3 for MDF. The imported boards during this same period were particle board 10 000m3 and 22 194m3 for MDF. The extrapolated expected imports for 2003 would be 12 362m3 and 35 045m3 for particle board and MDF respectively. According to the empirical study the market increase for particle board and MDF, for 2003, will be 18%. That means that the particle board market will increase to 590 000m3 and the MDF market to 130 000m3. The 2002 production capacity was 648 000m3 (particle board) and 155 000m3 for MDF. The Sonae factory in White River can produce either particle board or MDF and this influences the production capacities. According to various International databases the requirements for SA in 2020 will be 984 000m3 for particle board and 569 000m3 for MDF. Quick calculation show a shortfall of 414 000m3 for MDF in 2020 when compared to 2002 production capacity. First mover advantage will give the mover the major market share in SA. The demand will be there. All the above calculations have been done without taking the 2010 World Football event in SA into consideration. The question is – all the current players are almost on par to make it happen. The company with the burning desire to make it work will find the finance and will have the controlling market share.
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Park, Byung Dae. "Cure acceleration of phenol-formaldehyde (PF) adhesives for three-layer medium density fiberboard (MDF)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ39388.pdf.
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Youd, Stephen John. "The effects of crosslinking in the fracture properties of high and medium density polyethylene." Thesis, Manchester Metropolitan University, 1991. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306251.
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Bailey, Melissa. "Urban consolidation and residential restructuring in Adelaide : a study of people in medium density housing /." Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09AR/09arb155.pdf.
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Castro, Eduardo Martins de. "Estudo da usinabilidade de chapas MDF (Medium Density Fiberboard) para usinagem de desbaste e acabamento." Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-16092016-110705/.
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Este trabalho apresenta estudos de usinabilidade de chapas MDF (Medium Density Fiberboard), tendo por objetivo principal efetuar uma análise do desempenho de corte em relação à qualidade da superfície usinada e à força específica de corte paralela necessária, a fim de se verificar a influência dos parâmetros estudados para operações de usinagem de acabamento e desbaste, respectivamente. No estudo para operação de acabamento verificou-se a influência da espessura de corte,velocidade de avanço e sentido de corte, em operação de fresamento cilíndrico periférico, sobre a rugosidade superficial da borda das chapas MDF. Uma fresadora vertical foi utilizada para gerar as superfícies, cuja rugosidade superficial foi medida por um perfilômetro de apalpamento. No estudo para operação de desbaste, a força específica de corte paralela foi avaliada em função da variação do ângulo de saída, da espessura de corte e da profundidade de corte, em operação de corte ortogonal. Para tanto, foram empregadas uma plaina limadora e uma célula de carga de extensômetros resistivos, conectada a um programa de aquisição e análise de dados. A partir da análise dos resultados obtidos, foi possível identificar a influência de cada parâmetro de corte empregado.This work presents a MDF (Medium Density Fiberboard) machinability study aiming to carry out a cutting performance analysis regarding to surface quality and parallel specific cutting force, in order to verify the cutting parameters effect on the finishing and roughing machining operations, respectively. In the finishing study, it was verified the effect of the cutting thickness, cutting speed and direction of cutterhead rotation with relation to feed direction, in peripheral milling, on the MDF edges surface roughness. The surfaces were developed by a moulder, which roughness were measured by a stylus perfilometer. In the roughing study, the parallel specific cutting force was assessed in relation to the variation of the rake angle, cutting thickness and depth of cut, for the orthogonal cut. For this, it was used a planing machine and a resistance dynamometer, coupled in a data acquisition and analysis system. From the analysis of the obtained results, it was possible to identify the influence of each cutting parameter considered.
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Karol, Elizabeth. "Energy efficient design in housing of small floor area : appropriateness in housing for the aged." Thesis, Curtin University, 2003. http://hdl.handle.net/20.500.11937/902.
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This thesis seeks to address energy efficient design in a temperate climate in typical small, medium density housing, particularly in housing for the aged. The connections between energy efficient design and small, medium density housing were identified as contemporary issues related to Australian Government policies in two disparate areas. One policy area is reflected in the Government's commitment to assist older people, whether they are active, early retirees or the frail elderly, wealthy or poor, to live in their chosen place of residence. Increasingly this chosen place of residence may be a small, medium density dwelling. The other policy area is that related to reducing energy consumption in buildings. This policy is reflected in recently proclaimed building regulations aimed at reducing space heating/cooling requirements in housing. The building regulations include details of acceptable construction practice for energy efficiency that may not be appropriate in small, medium density housing. It was proposed in this thesis that extensive use of space heating and cooling in housing for the aged was required because well-established benchmarks for energy efficient design in a temperate climate were not generally appropriate in small, medium density dwellings and were particularly inappropriate in housing for the aged. `Appropriate' in this context referred to: indoor temperatures being acceptable without the need for space heating and cooling; retaining the site planning and general form of typical, medium density aged persons housing developments in suburban Australia; cost effectiveness over the life of a building; and fitting the needs of physically and financially vulnerable older people.The methods used to examine the notion of appropriateness commenced with a literature review that related to the general physical and economic status of older people and their needs and responses to space heating and cooling in the home. Further, the literature review considered the principles of energy efficient design and benchmark criteria for energy efficiency. Arising from the literature review, two tools of study were used in order to develop a set of data encapsulating the salient features of small, medium density housing. The first was a multiple case study of typical housing for the aged. This was conceived as a way of determining if small, medium density dwellings could provide appropriate indoor thermal conditions and/or were designed to be energy efficient. The indoor temperatures were monitored in summer and winter and annual energy consumption was established and statistically analysed. The building designs were analysed in terms of their orientation, glazing areas, wall areas, volumes of thermal mass and ventilation capacity and compared with benchmarks for energy efficient design. The second tool involved a series of computer simulations of a typical small, medium density dwelling. The simulation process was utilised to determine if a new set of benchmarks for energy efficient small, medium density dwellings were required that would incorporate the notion of appropriateness. From the multiple case study it was found that, irrespective of design, indoor temperatures in 98% of dwellings were above the acceptable maximum summer temperature of 27.4°C in still air and indoor temperatures in all dwellings were found to be below the acceptable minimum daytime temperature of 19.8°C.The findings also showed that some aspects of the benchmarks for energy efficient design were not appropriate in typical, medium density housing constructed specifically for the aged. From the simulation process it was discovered that acceptable temperatures could be achieved in small medium density housing if the principles of energy efficient design, incorporated within a new set of benchmarks, were integrated with appropriateness criteria for housing for the aged. The approach taken with the new benchmarks was to create both performance based and prescriptive design solutions. The performance model differs from the current benchmarks for energy efficient design in that it establishes key functional objectives for energy efficient design. Compared to the current benchmarks, the prescriptive design solutions show significant reductions in the areas of northerly glazing and total glazing. To compensate for the reduced area of northerly glazing, both direct and indirect means of solar gain are utilised for passive heating. The thesis outcomes have implications for three areas of the construction industry. The prescriptive design solutions presented in building regulations for energy efficiency in housing need to be qualified, the design briefs prepared for energy efficient construction of small, medium density housing need amendment and the approach taken by designers involved in energy efficient small, medium density housing needs to be reconsidered.
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Bueno, Marcus Antonio Pereira [UNESP]. "Painéis de Medium Density Fiberboard fabricados com bagaço de cana-de-açúcar e madeira de reflorestamento." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/124122.
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O objetivo deste trabalho foi analisar as potencialidades da utilização do bagaço de cana-de-açúcar (SC) aplicado aos painéis de MDF (Medium Density Fiberboard), juntamente com fibras de madeira de reflorestamento (WR) da espécie eucalipto, na indústria moveleira e de construção civil. Neste estudo, foram produzidos painéis de MDF em quatro traços: 100% WR (T2), 33%SC+67%WR (T3), 67%SC+33%WR (T4) e 100% SC (T5). Também foram analisadas as propriedades físicas e mecânicas, segundo a norma brasileira NBR 15316-3 (2009). A densidade alvo dos painéis foi de 700 kg/m, definida como painel de média densidade. Também foi realizado o ensaio por microscopia eletrônica de varredura, (MEV) para se obter e constatar o perfil do topo ou face do painel (parte que fica em contato com os pratos da prensa), e da parte usinada ou parte interna do painel. O adesivo utilizado foi a uréia-formaldeído, na proporção de 10% da massa total do painel. Os resultados analisados indicaram que o traço com 100% SC (T5) apresentou o melhor desempenho entre os trapos, atingidos em alguns casos os valores recomendados pela NBR 15316-2 (2009). Pelos resultados averiguados o bagaço de cana-de-açúcar apresentou bom potencial para a fabricação de painéis MDF, devendo ser estudado com maior aprimoramento
The objective of this study was to analyze the potentialities of using sugarcane bagasse (SC) applied to MDF panels (Medium Density Fiberboard), along with reflorestation wood fibers (WR) of eucalyptus species, in the industry of furniture and construction. In this study, it was produced panels of MDF in four traces: 100% WR (T2), 33% SC+67% WR (T3), 67% SC+33% WR (T4) and 100% SC (T5). Also it was analyzed its physical and mechanical properties, according to the Brazilian standard NBR 15316-3 (2009). The target density of the panels was 700 kg/m, defined as medium density fiberboard. In addition it was carried out surface analysis of the top and the internal part of the panel through Scanning Electron Microscopy (SEM). The panels were bonded with urea-formaldehyde, in the proportion of 10% by mass of the panel. The results indicated that the trace with 100% SC (T5) showed the best performance among the traces, reaching, in some cases, the values recommended by NBR 15316-2 (2009). This results shows the possibility of using sugarcane bagasse for the production of MDF panels, however it is recommended more studies to improve its physical and mechanical characteristics
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Sitz, Evan Donald. "Processing and Manufacture of Soybean and Wheat Straw Medium Density Fiberboard Utilizing Epoxidized Sucrose Soyate Resin." Thesis, North Dakota State University, 2016. https://hdl.handle.net/10365/27990.
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Soybean straw and wheat straw show promise as annually renewable alternative to traditional wood sources for fiberboard. Epoxidized sucrose soyate has shown high performance as a thermosetting resin and could be adapted for use in fiberboard. This research evaluated the physical and mechanical properties of medium density fiberboard using wheat and soy straw while using various binders, including epoxidized sucrose soyate. Additionally, several experiments were conducted to evaluate optimal process conditions for hammer milling of soy and wheat straw to reduce fines and maximize viable fiber content for fiberboard manufacture. Test results indicate that soy straw boards were not able to meet the properties of wheat straw boards on all levels. Epoxidized sucrose soyate was not effective as the sole binder but had similar properties when blended with MDI resin. Optimal conditions were identified to reduce fines and maximize the viable fiber fraction produced for both wheat and soy straw.North Dakota Soybean Council and the North Dakota Industrial Commission
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De, la Harpe Jeanette Carol. "Social factors affecting the design and management of state-subsidised medium-density housing in Cape Town." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5058.
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Includes bibliographical references (leaves 114-122).Many urban planners and designers have recognised the notable discrepancy between state policy in recent years supporting the densification of urban housing development, and broad acceptance of this approach by residents, in particular recipients of state-subsidised housing. This study sought to investigate the reasons for this in acknowledgement of the negative experiences of these residents, and to produce findings that could help to reduce the drawbacks still strongly associated with densified housing estates.
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Bueno, Marcus Antonio Pereira. "Painéis de Medium Density Fiberboard fabricados com bagaço de cana-de-açúcar e madeira de reflorestamento /." Bauru, 2014. http://hdl.handle.net/11449/124122.
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Orientador: Ivaldo De Domenico ValarelliBanca: Rosane Aparecida Gomes Battistelle
Banca: Maria Fátima do Nascimento
Resumo: O objetivo deste trabalho foi analisar as potencialidades da utilização do bagaço de cana-de-açúcar (SC) aplicado aos painéis de MDF (Medium Density Fiberboard), juntamente com fibras de madeira de reflorestamento (WR) da espécie eucalipto, na indústria moveleira e de construção civil. Neste estudo, foram produzidos painéis de MDF em quatro traços: 100% WR (T2), 33%SC+67%WR (T3), 67%SC+33%WR (T4) e 100% SC (T5). Também foram analisadas as propriedades físicas e mecânicas, segundo a norma brasileira NBR 15316-3 (2009). A densidade alvo dos painéis foi de 700 kg/m, definida como painel de média densidade. Também foi realizado o ensaio por microscopia eletrônica de varredura, (MEV) para se obter e constatar o perfil do topo ou face do painel (parte que fica em contato com os pratos da prensa), e da parte usinada ou parte interna do painel. O adesivo utilizado foi a uréia-formaldeído, na proporção de 10% da massa total do painel. Os resultados analisados indicaram que o traço com 100% SC (T5) apresentou o melhor desempenho entre os trapos, atingidos em alguns casos os valores recomendados pela NBR 15316-2 (2009). Pelos resultados averiguados o bagaço de cana-de-açúcar apresentou bom potencial para a fabricação de painéis MDF, devendo ser estudado com maior aprimoramento
Abstract: The objective of this study was to analyze the potentialities of using sugarcane bagasse (SC) applied to MDF panels (Medium Density Fiberboard), along with reflorestation wood fibers (WR) of eucalyptus species, in the industry of furniture and construction. In this study, it was produced panels of MDF in four traces: 100% WR (T2), 33% SC+67% WR (T3), 67% SC+33% WR (T4) and 100% SC (T5). Also it was analyzed its physical and mechanical properties, according to the Brazilian standard NBR 15316-3 (2009). The target density of the panels was 700 kg/m, defined as medium density fiberboard. In addition it was carried out surface analysis of the top and the internal part of the panel through Scanning Electron Microscopy (SEM). The panels were bonded with urea-formaldehyde, in the proportion of 10% by mass of the panel. The results indicated that the trace with 100% SC (T5) showed the best performance among the traces, reaching, in some cases, the values recommended by NBR 15316-2 (2009). This results shows the possibility of using sugarcane bagasse for the production of MDF panels, however it is recommended more studies to improve its physical and mechanical characteristics
Mestre
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Swankie, William. "Effects of Temperature on the Emission Rate of Formaldehyde from Medium Density Fiberboard in a Controlled Chamber." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6960.
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Formaldehyde is a colorless gas that is found naturally in the environment. It is a popular additive in many consumer products including composite wood products. Composite wood products are engineered wood panels produced from pressing pieces, chips, particles, or fibers of wood together at high temperatures held together with a bonding agent. This bonding agent is often formaldehyde-containing resins that are known to release formaldehyde over time. This is concerning because of the carcinogenic classification of formaldehyde, the wide spread application of composite wood products, and the increasing amount of time spent in the indoor environment.
In a controlled 0.53 m3 chamber, a panel of medium density fiberboard (MDF) with a surface area of 4.49 m2 was subjected to multiple temperatures to measure formaldehyde emissions. The panels were allowed to acclimate for 48 hours followed by a 72 hour sample period using passive diffusive monitors at temperatures: 26.1, 29.3, 34.1, and 38.9 °C. The results of the study found a strong relationship (R2 = 0.9954) between the emission rate of formaldehyde from MDF and temperature. The emission rate increased 192% between 26.1 °C and 38.9 °C. The results of the study indicate that as temperature increases, the amount of formaldehyde emitted from a panel of MDF also increases. This results in higher airborne concentrations of formaldehyde in environments where the panels are present.
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Handa, Dev Roberto. "More of the same--why medium-density, low-rise housing is underrepresented in suburban Toronto housing markets." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/66727.
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Dinhane, Fernanda Christiane Rossetto [UNESP]. "Propriedades físico-mecânicas de painéis de mdp (medium density particleboard) constituído de bambu e fibra de coco." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/136308.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A matéria-prima utilizada pelas indústrias de painéis é a madeira de reflorestamento, sendo de diversas espécies. Visando o aproveitamento dos resíduos agroindustriais e a melhora no desempenho físico-mecânico dos painéis, a utilização de outros materiais como o bagaço de cana, o sisal, a casca de café e a fibra de coco são algumas alternativas. Além destes materiais, o bambu destaca-se pela sua alta produtividade e pela menor quantidade de área plantada quando comparada com outras culturas, como o Eucalipto. Números que representam a quantidade de resíduos gerados, no caso da fibra de coco no Brasil são de aproximadamente 3,7 mil toneladas considerando que um fruto pesa dois quilogramas, no ano de 2014. O objetivo deste trabalho foi avaliar as propriedades físicas e mecânicas de painéis MDP (Medium Density Particleboard), fabricado com três camadas, constituídos de fibra de coco e partículas de bambu, com variações nas porcentagens utilizadas de fibra de coco na camada interna do painel. Para a fabricação dos painéis utilizou-se partículas retidas em peneiramento com peneiras de 9 mesh, 16 mesh, 35 mesh e 60 mesh. Através do processamento mecânico dos materiais e da adição de adesivo poliuretano bi-componente à base de óleo de mamona foram confeccionado painéis de bambu com fibra de coco. Painéis estes constituídos de duas camadas externas de bambu e a camada interna de fibra de coco mais bambu. Em termos de porcentagem de material utilizado em um painel, 60 % representa a parte interna e o restante corresponde à parte externa, 20 % acima e 20 % abaixo da camada interna. Sendo que, as variações das porcentagens de fibra de coco na camada interna foram de 0% para o Tratamento 0-100, 10% para o Tratamento 10-90, 20% para o Tratamento 20-80 e 30% para o Tratamento 30-70. Para cada tratamento foram realizados cinco repetições, totalizando 20 painéis produzidos. As normas utilizadas como referência para avaliação físico-mecânica foram NBR 14810-2 (2013), ANSI A208.1 (1999) e CS 236-66 (1968), avaliando as propriedades físicas e mecânicas. Foram determinados o teor de umidade, densidade, inchamento em espessura 24 horas, absorção de água 24 horas, resistência à flexão estática e módulo de elasticidade, resistência à tração perpendicular e arrancamento de parafuso no topo e na superfície. O tratamento 0-100 obteve os maiores valores médios de resistência. Atendeu as especificações das três normas, exceto a CS 236-66 (1968) para o MOE. Com o objetivo da utilização da fibra de coco, o tratamento 30-70 foi o tratamento que dentre os três (tratamentos 10-90, 20-80 e 30-70) obteve os maiores valores médios de resistência, viabilizando assim o uso da fibra de coco com o bambu, para a produção de móveis e de painéis de revestimento térmico acústico que necessitam de valores mínimos de resistência.
The raw material used by panels industries is reforested wood, and of several species. Targeting the use of agro-industrial waste and the improvement in physical and mechanical performance of the panels, the use of other materials such as sugarcane bagasse, sisal, coffee husk and coir are some alternatives. In addition to these materials, bamboo stands out for its high productivity and the lower amount of planted area compared to other crops such as Eucalyptus. Numbers representing the amount of waste generated in the case of coconut fiber in Brazil are approximately 3.7 thousand tons whereas a fruit weighs two kilograms, in the year 2014. The objective of this study was to evaluate the physical and mechanical properties MDP panels (Medium Density Particleboard) made of three layers consisting of coconut and bamboo fiber particles with variations in the percentages of coconut fiber used in the inner layer panel. For the manufacture of the panels used to particulates collected in sieve with mesh sieve 9, 16 mesh, 35 mesh and 60 mesh. Through the mechanical processing of the materials and the addition of two-component polyurethane adhesive on castor oil-based panels were made with bamboo coconut fiber. These panels consisting of two outer layers of bamboo and the inner layer coconut more bamboo fiber. In terms of percentage of material used in a panel, 60% is inside, and the rest is to the outside, 20% above and 20% below the inner layer. Since the variations of the percentages of coconut fiber in the inner layer was 0% for the Treatment 0-100, 10% for the Treatment 10-90 20% 20-80 for the treatment and 30% for the Treatment 30- 70. For each treatment were performed five repetitions, totaling 20 panels produced. The standards used as reference to physical and mechanical evaluation were NBR 14810-2 (2013), ANSI A208.1 (1999) and CS 236-66 (1968), evaluating the physical and mechanical properties. They were determined moisture content, density, thickness swelling 24 hours, water absorption 24 hours, static bending strength and modulus of elasticity, internal bond and screw pullout top and bottom surface. Treatment 0-100 obtained the highest average values of resistance. Met the specifications of the three standards, except CS 236-66 (1968) to the MOE. With the goal of using coir, treatment 30-70 was the treatment of the three (treatments 10-90, 20-80 and 30-70) had the highest average values of resistance, thus enabling the use of fiber coconut with bamboo, for the production of furniture and sound insulated panels requiring minimum resistance values.
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Dinhane, Fernanda Christiane Rossetto. "Propriedades físico-mecânicas de painéis de mdp (medium density particleboard) constituído de bambu e fibra de coco /." Bauru, 2016. http://hdl.handle.net/11449/136308.
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Orientador: Ivaldo De Domenico ValarelliCo-orientador: Cristiane Inácio de Campos
Banca: Rosane Aparecida G. Battsitelle
Banca: Maria Fátima do Nascimento
Resumo: A matéria-prima utilizada pelas indústrias de painéis é a madeira de reflorestamento, sendo de diversas espécies. Visando o aproveitamento dos resíduos agroindustriais e a melhora no desempenho físico-mecânico dos painéis, a utilização de outros materiais como o bagaço de cana, o sisal, a casca de café e a fibra de coco são algumas alternativas. Além destes materiais, o bambu destaca-se pela sua alta produtividade e pela menor quantidade de área plantada quando comparada com outras culturas, como o Eucalipto. Números que representam a quantidade de resíduos gerados, no caso da fibra de coco no Brasil são de aproximadamente 3,7 mil toneladas considerando que um fruto pesa dois quilogramas, no ano de 2014. O objetivo deste trabalho foi avaliar as propriedades físicas e mecânicas de painéis MDP (Medium Density Particleboard), fabricado com três camadas, constituídos de fibra de coco e partículas de bambu, com variações nas porcentagens utilizadas de fibra de coco na camada interna do painel. Para a fabricação dos painéis utilizou-se partículas retidas em peneiramento com peneiras de 9 mesh, 16 mesh, 35 mesh e 60 mesh. Através do processamento mecânico dos materiais e da adição de adesivo poliuretano bi-componente à base de óleo de mamona foram confeccionado painéis de bambu com fibra de coco. Painéis estes constituídos de duas camadas externas de bambu e a camada interna de fibra de coco mais bambu. Em termos de porcentagem de material utilizado em um painel, 60 % representa a p... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The raw material used by panels industries is reforested wood, and of several species. Targeting the use of agro-industrial waste and the improvement in physical and mechanical performance of the panels, the use of other materials such as sugarcane bagasse, sisal, coffee husk and coir are some alternatives. In addition to these materials, bamboo stands out for its high productivity and the lower amount of planted area compared to other crops such as Eucalyptus. Numbers representing the amount of waste generated in the case of coconut fiber in Brazil are approximately 3.7 thousand tons whereas a fruit weighs two kilograms, in the year 2014. The objective of this study was to evaluate the physical and mechanical properties MDP panels (Medium Density Particleboard) made of three layers consisting of coconut and bamboo fiber particles with variations in the percentages of coconut fiber used in the inner layer panel. For the manufacture of the panels used to particulates collected in sieve with mesh sieve 9, 16 mesh, 35 mesh and 60 mesh. Through the mechanical processing of the materials and the addition of two-component polyurethane adhesive on castor oil-based panels were made with bamboo coconut fiber. These panels consisting of two outer layers of bamboo and the inner layer coconut more bamboo fiber. In terms of percentage of material used in a panel, 60% is inside, and the rest is to the outside, 20% above and 20% below the inner layer. Since the variations of the percentages... (Complete abstract click electronic access below)
Mestre
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Abdu-Aguye, Umar-Faruk. "On lowering the error floor of short-to-medium block length irregular low density parity check codes." Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/11156.
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Gallager proposed and developed low density parity check (LDPC) codes in the early 1960s. LDPC codes were rediscovered in the early 1990s and shown to be capacity approaching over the additive white Gaussian noise (AWGN) channel. Subsequently, density evolution (DE) optimized symbol node degree distributions were used to significantly improve the decoding performance of short to medium length irregular LDPC codes. Currently, the short to medium length LDPC codes with the lowest error floor are DE optimized irregular LDPC codes constructed using progressive edge growth (PEG) algorithm modifications which are designed to increase the approximate cycle extrinsic message degrees (ACE) in the LDPC code graphs constructed. The aim of the present work is to find efficient means to improve on the error floor performance published for short to medium length irregular LDPC codes over AWGN channels in the literature. An efficient algorithm for determining the girth and ACE distributions in short to medium length LDPC code Tanner graphs has been proposed. A cyclic PEG (CPEG) algorithm which uses an edge connections sequence that results in LDPC codes with improved girth and ACE distributions is presented. LDPC codes with DE optimized/’good’ degree distributions which have larger minimum distances and stopping distances than previously published for LDPC codes of similar length and rate have been found. It is shown that increasing the minimum distance of LDPC codes lowers their error floor performance over AWGN channels; however, there are threshold minimum distances values above which there is no further lowering of the error floor performance. A minimum local girth (edge skipping) (MLG (ES)) PEG algorithm is presented; the algorithm controls the minimum local girth (global girth) connected in the Tanner graphs of LDPC codes constructed by forfeiting some edge connections. A technique for constructing optimal low correlated edge density (OED) LDPC codes based on modified DE optimized symbol node degree distributions and the MLG (ES) PEG algorithm modification is presented. OED rate-1⁄2 (n, k)=(512, 256) LDPC codes have been shown to have lower error floor over the AWGN channel than previously published for LDPC codes of similar length and rate. Similarly, consequent to an improved symbol node degree distribution, rate 1⁄2 (n, k)=(1024, 512) LDPC codes have been shown to have lower error floor over the AWGN channel than previously published for LDPC codes of similar length and rate. An improved BP/SPA (IBP/SPA) decoder, obtained by making two simple modifications to the standard BP/SPA decoder, has been shown to result in an unprecedented generalized improvement in the performance of short to medium length irregular LDPC codes under iterative message passing decoding. The superiority of the Slepian Wolf distributed source coding model over other distributed source coding models based on LDPC codes has been shown.
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Hilger, Thomas. "Medium Modifications of Mesons." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-94078.
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Das Zusammenspiel von Hadronen und Modifikationen ihrer Eigenschaften auf der einen Seite und spontaner chiraler Symmetriebrechung und Restauration auf der anderen Seite wird untersucht. Es werden die QCD Summenregeln für D und B Mesonen in kalter Materie berechnet. Wir bestimmen die Massenaufspaltung von D - D-bar und B - B-bar Mesonen als Funktion der Kerndichte und untersuchen den Einfluss verschiedener Kondensate in der Näherung linearer Dichteabhängigkeit. Die Analyse beinhaltet ebenfalls D_s und D^*_0 Mesonen. Es werden QCD Summenregeln für chirale Partner mit offenem Charmfreiheitsgrad bei nichtverschwindenden Nettobaryonendichten und Temperaturen vorgestellt. Es wird die Differenz sowohl von pseudoskalaren und skalaren Mesonen, als auch von Axialvektor- und Vektormesonen betrachtet und die entsprechenden Weinberg-Summenregeln hergeleitet. Basierend auf QCD Summenregeln werden die Auswirkungen eines Szenarios auf das rho Meson untersucht, in dem alle chiral ungeraden Kondensate verschwinden wohingegen die chiral symmetrischen Kondensate ihren Vakuumwert behalten. Die komplementären Folgerungen einer Massenverschiebung und Verbreiterung der rho Mesonanregung werden diskutiert. Ein alternativer Zugang basierend auf gekoppelten Dyson-Schwinger- und Bethe-Salpeter-Gleichungen für Quarkbindungszustände wird untersucht. Zu diesem Zwecke wird die analytische Struktur des Quarkpropagators in der komplexen Ebene numerisch untersucht und die Möglichkeit getestet die Anwendbarkeit auf den Sektor der schwer-leicht Quark Systeme im skalaren und pseudoskalaren Kanal, wie dem D Meson, durch Variation des Impulsteilungsparameters zu erweitern. Die Lösungen der Dyson-Schwinger-Gleichung in der Wigner-Weyl-Phase der chiralen Symmetrie bei nichtverschwindenden Stromquarkmassen wird benutzt um den Fall einer expliziten Symmetriebrechung ohne spontane Symmetriebrechung zu untersuchenThe interplay of hadron properties and their modification in an ambient nuclear medium on the one hand and spontaneous chiral symmetry breaking and its restoration on the other hand is investigated. QCD sum rules for D and B mesons embedded in cold nuclear matter are evaluated. We quantify the mass splitting of D - D-bar and B - B-bar mesons as a function of the nuclear matter density and investigate the impact of various condensates in linear density approximation. The analysis also includes D_s and $D^*_0 mesons. QCD sum rules for chiral partners in the open-charm meson sector are presented at nonzero baryon net density or temperature. We focus on the differences between pseudo-scalar and scalar as well as vector and axial-vector D mesons and derive the corresponding Weinberg type sum rules. Based on QCD sum rules we explore the consequences of a scenario for the rho meson, where the chiral symmetry breaking condensates are set to zero whereas the chirally symmetric condensates remain at their vacuum values. The complementarity of mass shift and broadening is discussed. An alternative approach which utilizes coupled Dyson-Schwinger and Bethe-Salpter equations for quark-antiquark bound states is investigated. For this purpose we analyze the analytic structure of the quark propagators in the complex plane numerically and test the possibility to widen the applicability of the method to the sector of heavy-light mesons in the scalar and pseudo-scalar channels, such as the D mesons, by varying the momentum partitioning parameter. The solutions of the Dyson-Schwinger equation in the Wigner-Weyl phase of chiral symmetry at nonzero bare quark masses are used to investigate a scenario with explicit but without dynamical chiral symmetry breaking
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Tasooji, Mohammad. "Effects of Thermomechanical Refining on Douglas fir Wood." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/96218.
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Medium density fiberboard (MDF) production uses thermomechanically refined fiber processed under shear with high pressure steam. The industry evaluates fiber quality with visual and tactile inspection, emphasizing fiber dimensions, morphology, and bulk density. Considering wood reactivity, the hypothesis is that a variety of chemical and physical changes must occur that are not apparent in visual/tactile inspection. An industry/university cooperation, this work studies effects of refining energy (adjusted by refiner-plate gap) on fiber: size, porosity, surface area, surface and bulk chemistry, fiber crystallinity and rheology, and fiber interaction with amino resins. The intention is to reveal novel aspects of fiber quality that might impact MDF properties or process control efficiency, specific to a single industrial facility.
In cooperation with a North American MDF Douglas fir plant, two refining energies were used to produce resin and additive-free fibers. Refining reduced fiber dimensions and increased bulk density, more so at the highest energy. Thermoporosimetry showed increases in sub-micron scale porosity, greatest at the highest energy. Mercury intrusion porosimetry (MIP) revealed porosity changes on a higher dimensional scale. Brunauer-Emmett-Teller gas adsorption and MIP showed that refining increased specific surface area, more so at the highest energy. Inverse gas chromatography showed that the lowest refining energy produced surfaces dominated by lignin and/or extractives. The highest energy produced more fiber damage, revealing higher energy active sites. A novel rheological method was devised to study fiber compaction and densification; it did not distinguish fiber types, but valuable aspects of mechano-sorption and densification were observed.
Refining caused substantial polysaccharide degradation, and other degradative effects that sometimes correlated with higher refining energy. Lignin acidolysis was detected using nitrobenzene oxidation, conductometric titration of free phenols, and formaldehyde determination. Formaldehyde was generated via the C2 lignin acidolysis pathway, but C3 cleavage was the dominant lignin reaction. Observations suggested that in-line formaldehyde monitoring might be useful for process control during biomass processing. According to rheological and thermogravimetric analysis, lignin acidolysis was not accompanied by repolymerization and crosslinking. Lignin repolymerization must have been prevented by the reaction of benzyl cations with non-lignin nucleophiles. This raises consideration of additives that compete for lignin benzyl cations, perhaps to promote lignin crosslinking and/or augment the lignin network with structures that impart useful properties.
Fiber/amino resin interactions were studied with differential scanning calorimetry (DSC) and X-ray diffraction (XRD). All fiber types, refined and unrefined, caused only a slight increase in melamine-urea-formaldehyde (MUF) resin reactivity. Generally, all fiber types decreased the enthalpy of MUF cure, suggesting fiber absorption of small reactive species. But DSC did not reveal any dependency on fiber refining energy. According to XRD, all fiber types reduced crystallinity in cured MUF, more so with refined fiber, but independent of refining energy. The crystallinity in cured urea-formaldehyde resin was studied with one fiber type (highest refining energy); it caused a crystallinity decrease that was cure temperature dependent. This suggests that resin crystallinity could vary through the thickness of an MDF panel.PHD
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Karol, Elizabeth. "Energy efficient design in housing of small floor area : appropriateness in housing for the aged." Curtin University of Technology, Faculty of Built Environment, Art and Design, 2003. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=14106.
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This thesis seeks to address energy efficient design in a temperate climate in typical small, medium density housing, particularly in housing for the aged. The connections between energy efficient design and small, medium density housing were identified as contemporary issues related to Australian Government policies in two disparate areas. One policy area is reflected in the Government's commitment to assist older people, whether they are active, early retirees or the frail elderly, wealthy or poor, to live in their chosen place of residence. Increasingly this chosen place of residence may be a small, medium density dwelling. The other policy area is that related to reducing energy consumption in buildings. This policy is reflected in recently proclaimed building regulations aimed at reducing space heating/cooling requirements in housing. The building regulations include details of acceptable construction practice for energy efficiency that may not be appropriate in small, medium density housing. It was proposed in this thesis that extensive use of space heating and cooling in housing for the aged was required because well-established benchmarks for energy efficient design in a temperate climate were not generally appropriate in small, medium density dwellings and were particularly inappropriate in housing for the aged. `Appropriate' in this context referred to: indoor temperatures being acceptable without the need for space heating and cooling; retaining the site planning and general form of typical, medium density aged persons housing developments in suburban Australia; cost effectiveness over the life of a building; and fitting the needs of physically and financially vulnerable older people.The methods used to examine the notion of appropriateness commenced with a literature review that related to the general physical and economic status of older people and their needs and responses to space heating and cooling in the home. Further, the literature review considered the principles of energy efficient design and benchmark criteria for energy efficiency. Arising from the literature review, two tools of study were used in order to develop a set of data encapsulating the salient features of small, medium density housing. The first was a multiple case study of typical housing for the aged. This was conceived as a way of determining if small, medium density dwellings could provide appropriate indoor thermal conditions and/or were designed to be energy efficient. The indoor temperatures were monitored in summer and winter and annual energy consumption was established and statistically analysed. The building designs were analysed in terms of their orientation, glazing areas, wall areas, volumes of thermal mass and ventilation capacity and compared with benchmarks for energy efficient design. The second tool involved a series of computer simulations of a typical small, medium density dwelling. The simulation process was utilised to determine if a new set of benchmarks for energy efficient small, medium density dwellings were required that would incorporate the notion of appropriateness. From the multiple case study it was found that, irrespective of design, indoor temperatures in 98% of dwellings were above the acceptable maximum summer temperature of 27.4°C in still air and indoor temperatures in all dwellings were found to be below the acceptable minimum daytime temperature of 19.8°C.
The findings also showed that some aspects of the benchmarks for energy efficient design were not appropriate in typical, medium density housing constructed specifically for the aged. From the simulation process it was discovered that acceptable temperatures could be achieved in small medium density housing if the principles of energy efficient design, incorporated within a new set of benchmarks, were integrated with appropriateness criteria for housing for the aged. The approach taken with the new benchmarks was to create both performance based and prescriptive design solutions. The performance model differs from the current benchmarks for energy efficient design in that it establishes key functional objectives for energy efficient design. Compared to the current benchmarks, the prescriptive design solutions show significant reductions in the areas of northerly glazing and total glazing. To compensate for the reduced area of northerly glazing, both direct and indirect means of solar gain are utilised for passive heating. The thesis outcomes have implications for three areas of the construction industry. The prescriptive design solutions presented in building regulations for energy efficiency in housing need to be qualified, the design briefs prepared for energy efficient construction of small, medium density housing need amendment and the approach taken by designers involved in energy efficient small, medium density housing needs to be reconsidered.
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Wheeler, Tom. "An analysis of the effectiveness of mains water reduction strategies in a medium density residential development in metropolitan Perth." Thesis, Wheeler, Tom (2019) An analysis of the effectiveness of mains water reduction strategies in a medium density residential development in metropolitan Perth. Honours thesis, Murdoch University, 2019. https://researchrepository.murdoch.edu.au/id/eprint/54832/.
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This thesis reviews and quantifies the implementation of mains water reduction strategies in a medium density residential development in a city with a drying climate. WGV by DevelopmentWA (WGV) is a 2.2-hectare infill development in the Fremantle suburb White Gum Valley, Perth, Australia. WGV incorporates a number of mains water reduction strategies including water efficiencies, conservation and alternative sources.
This thesis investigates the implementation of these mains water reduction strategies, providing understanding on the impact of the strategies for residents living in the development. Over 60 smart meters were installed at the site to record data on mains, bore and rain water consumption for three dwelling typologies including:
- Detached dwellings: Assumed occupancy of 2.8 people per dwelling with an average of 105m2 per person with no common walls between dwellings.
- Attached dwellings: Assumed occupancy of 2.8 people per dwelling with an average area of 45m2 per person with common walls between dwellings.
- Multi-residential (Apartment) dwellings: Assumed occupancy of 1.8 people per dwelling with an average area of 55m2 per person.
The results demonstrated that residents living in WGV reduce their total water consumption by 48% whilst reducing their mains water consumption by approximately 64% in comparison to the typical Perth home. This is an 8% difference to the preliminary modelling completed by Josh Byrne & Associates (JBA) which predicted a mains water savings of 72%.
Attached dwelling residents were the lowest mains water consumers, using 20kL/person of mains water per year (81% reduction on Perth average) whilst Apartment residents consume 32kL per year (70% reduction) and Detached residents consume 52kL per year (51% reduction).
The thesis also found that the community bore system had been implemented successfully. Direct on-site infiltration was determined to be greater than the groundwater abstraction rate, leading to the conclusion that the community bore at WGV is sustainably managed.
Future policy implications following this study should include industry and governmental agencies investigating the implementation of small-scale decentralised alternative water sources and the water efficiencies and conservation strategies presented in this thesis.
A number of further studies are recommended including a detailed analysis of the Design Guidelines provided to residents by Development WA to further understand the large variation in water consumption levels of resident living within the WGV precinct. This study would include household audits and surveys with residents to provide a breakdown of the effectiveness of each water reduction initiative implemented to better understand the influence of the Design Guidelines.
Overall, WGV has been successful at reducing its mains water consumption by 64% which is within 10% of the predicted savings in the preliminary modelling completed by JBA.
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Li, Junqiu. "Physical and Mechanical Properties of Medite® MDF Exterior from Acetylated Wood Fibers." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-76444.
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Currently, the demand for wood-based panels has been growing solidly in European countries. Medium density fibreboard (MDF) manifests the potentialities for outstanding physical and mechanical properties. However, MDF from different fiber sources is normally designed for internal applications due to the poor moisture resistant capability. This study was conducted on acetylated MDF (Medite® MDF Exterior) to evaluate how physical (i.e. density, moisture content, dimensional stability, thickness swelling) and mechanical (i.e. modulus of elasticity, internal bonding strength before and after accelerated aging, bending stiffness and bending strength) properties behave at different relative humidity (i.e. 35 %, 65 % and 85 % RH at constant temperature of 20 ℃) levels. Bending stiffness was measured non-destructively by means of resonance method. The material used for control samples was commercial MDF. The size, quantity, conditioning and test method were followed in accordance with respective standards. The results showed that physical and mechanical properties were less influenced by Medite® MDF Exterior compared to commercial MDF. Medite® MDF Exterior were superior to commercial MDF in moisture resistance. Medite® MDF Exterior had more stable mechanical properties than commercial MDF with the changes of relative humidity.
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David, Noemi. "Asymptotic analysis for a model of tumor growth: from a cell density model to a Hele-Shaw problem." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/17066/.
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In questa tesi si presenta l'analisi asintotica di un modello di crescita tumorale, seguendo l'articolo The Hele–Shaw Asymptotics for Mechanical Models of Tumor Growth (2014) di Perthame B., Quiròs F. e Vàzquez J.L.
Tramite l'analisi asintotica è possibile costruire una correlazione tra i due principali approcci utilizzati nella descrizione del fenomeno: modelli della densità cellulare e problemi a frontiera libera. I primi descrivono l'evoluzione della popolazione cellulare e la sua interazione con fattori esterni (ossigeno, glucosio, sostanze chimiche) attraverso sistemi di equazioni differenziali. I secondi descrivono il movimento del tumore attraverso modelli a frontiera libera, in quanto, nelle prime fasi del suo sviluppo, i contorni del tumore sono ben definiti.
Nel modello illustrato in questa tesi, si assume che il movimento delle cellule sia guidato dalla legge di Darcy, la quale è solitamente usata per descrivere il flusso di un fluido in un mezzo poroso. Si considera quindi una PME (porous medium equation) che governa l'evoluzione della densità cellulare. Si dimostra che il limite della soluzione dell'equazione esiste e soddisfa un problema a frontiera libera del tipo Hele-Shaw. Si dimostra inoltre l'unicità di tale soluzione limite.
I risultati analoghi vengono dimostrati anche per un sistema che comprende una seconda equazione di diffusione-reazione, la quale descrive l'evoluzione della concentrazione di generici nutrienti (solitamente ossigeno e glucosio).
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Colyn, Robin. "Optimising camera trap density and position to determine medium and large mammal species richness and occupancy on the Cape Peninsula, South Africa." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2433.
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Thesis (MTech (Nature Conservation))--Cape Peninsula University of Technology, 2016.Largely due to anthropogenic causes, biodiversity and particularly species diversity is changing at an extraordinary rate, with declines in species abundance, community composition and extinction risk being of crucial concern. Monitoring of state variables of biodiversity such as species richness and occupancy are of significant importance in determining the severity of threats placed on species, populations and communities. As a non-invasive monitoring method camera traps are noted as being an effective, accurate and rapid means of compiling species richness estimates of medium to large terrestrial mammals. However, crucial elements of camera trap survey design are rarely empirically addressed, which has questioned the need for a standardised camera trapping protocol. Table Mountain National Park (TMNP) is a protected area that is under serious anthropogenic pressure through urban and peri-urban development. Although it is the last refuge for a number of large mammal species on the Cape Peninsula, current mammalian species richness knowledge within the TMNP are limited. Accurate and current species richness estimates are therefore needed within TMNP and more specifically the Cape of Good Hope (CoGH), which exclusively hosts a number of medium and large mammal species. The aims of this study were to optimise a camera survey protocol for the Peninsula region, with a focus on camera density, placement and survey duration that will enable accurate estimations of medium to large mammal species richness and occupancy.
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Pal, Maninder. "Leak detection and location in polyethylene pipes." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/15181.
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This thesis is focused on the application of cross-correlation technique for leak detection and location in medium density polyethylene (MDPE) pipes. A leaking water pipe generates noise that depends primarily on water pressure, pipe characteristics and the leak size and shape. This noise, commonly called leak signals, can be used for the purpose of leak detection and leak location in MDPE pipes. A correlation technique is typically employed to detect, position and characterise these water leaks and is proved to be very efficient for metallic pipes. However, the same is not true for MDPE pipes where the attenuation rate with distance of the leak/source signal is very high, and the generated leak signals are of low frequency and narrow bandwidth. In order to locate leak with good accuracy in MDPE pipes, the correlation process relies on the estimation of speed of leak signals in water/pipe and the time delay between leak signals measured at two locations. For time delay estimation, a correlation function is used. Its accuracy depends upon the sharpness of the correlation peak, type and positioning of sensor, and the processing of signals obtained, which in turn further depends upon the characteristics of leak signals. In MDPE pipes, leak signals are of low frequency and narrow bandwidth; however, their frequency response is not well characterised. Therefore, this thesis presents an analytical model to explain the acoustic characteristics of leak signals in MDPE pipes. The model is used to study the effects of the cut-off frequencies of low, high and band pass digital filters and the selection of acoustic/vibration sensors for the correlation technique. It detailed the importance of the cut-off frequency of the high pass filter and the insensitivity of the correlation function to the cut off frequency of the low pass filter.
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Awe, Temitope Abidemi. "The prospect of providing low-income medium density housing in developing countries : problems and opportunities with special reference to Cape Town, South Africa." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/5603.
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Includes bibliography.It is thus proposed in this thesis that low-income medium-density developments, located appropriately in inner city areas to kick-start settlements that are integrated, compact and promote mixed land uses, as well as aspiring towards sustainable urban development, are needed in the cities of developing countries. A typical example of such a housing development is Springfield Terrace Woodstock, Cape Town. This pilot project, demonstrating how the provision oflow-income medium-density housing (in the fonn of three- to four-storey walk-up blocks of flats) can be provided in central Cape Town and how these benefit from the existing bulk infrastructure. It further demonstrates how this housing type could be located and utilised to encourage a shift away from low-density to medium-density housing, particularly with regard to lowincome earners.
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Gupta, Arun. "Modelling and Optimisation of MDF Hot Pressing." Thesis, University of Canterbury. Chemical and Process Engineering, 2007. http://hdl.handle.net/10092/4200.
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There are four big medium density fibreboard (MDF) plants in New Zealand with a total production capacity of close to one million cubic meters per year. A significant quantity of boards (nearly 3% or about 30,000 cubic meters per year) is rejected due to defects such as weak core, low modulus of rupture and elasticity, low internal bonding and delamination. The main cause of these defects, is lack of complete understanding of the inter relationship during the hot-pressing stage between the initial inputs such as temperature, moisture content, platen pressure and its impact on the properties of boards. The best solution is to develop a mathematical model to assist in understanding these relationships and to solve the equations in the model by using advanced software. This will reduce the number of expensive experiments and will enable us to see some of the parameters, which are otherwise difficult to visualise. Several earlier researchers have tried to model hot pressing of wood composites, mostly either for particle board or oriented strand board (OSB), and only a few are for MDF. The type of numerical methods used to solve the model equations and various assumptions, changes from one investigator to the other. The non-availability of source code to convert the mathematical equations into programme, is one of the reasons for this model development. To improve the productivity of MDF plants in New Zealand, there was a need to develop a computer programme which can include all the latest findings and can remove the defects which are present in earlier models. This model attempts a more complete integration than in the previous models of all the components such as heat transfer, moisture movement and vertical density profile formation in a one-dimensional model of hot pressing of MDF. One of the important features added in the heat and mass transfer part of the model is that the equilibrium moisture content (EMC) equation given for solid wood was modified to be applicable for the MDF fibres. In addition, this EMC equation can cover the complete range of hot pressing temperature from 160ºC to 200ºC. The changes in fibre moisture content due to bound water diffusion, which was were earlier neglected, was considered. The resin curing reactions for phenol formaldehyde and urea formaldehyde resins are also incorporated into the model, with the energy and water released during the curing reaction being included in the energy and mass balances. The validation of the heat and mass transfer model was done by comparing the values of core temperature and core pressure from the model and the experiments. The experimental value of core pressure and core temperature is obtained by putting a thermocouple and pressure transducer in the middle of the mat. The experimental core temperature results show qualitative agreement with the predicted results. In the beginning, the core temperatures from both experiment and model overlap each other. In the middle of the press cycle, the experimental core temperature is higher by 10ºC and by the end the difference decreases to 5ºC. The vertical density profile (VDP) is a critical determining factor for the strength and quality of MDF panels. The earlier concept of ratio of modulus of elasticity of the layer to the sum of modulus of elasticity of all the layers in the previous time step, given by Suo and Bowyer (1994), is refined with the latest published findings. The equation given by Carvalho et al. (2001) is used to calculate the MOE of different layers of the mat. The differential equation of a Maxwell element given by Zombori (2001) is used to measure stress, nonlinear strain function and relaxation of fibres. The model gives good agreement of peak and core density at lower platen temperature at 160ºC but with the increase of platen temperature to 198ºC, the rise in peak density is comparatively higher. There is a distinct increase in predicted peak density by 150 kg/m³ in comparison to the experimental result, where the increase is only by 10 kg/m³. There is a large decline (50 kg/m³) in core density in the experimental results in comparison to only a slight decline (13 kg/m³) in the predicted results. The use of Matlab provides a very convenient platform for producing graphical results. The time of computation at present is nearly 20 hrs in a personal computer with Pentium four processor and one GB RAM. The model can predict properties of a pressed board for the standard manufacturing conditions and also the new hot pressing technologies such as the use of steam injection or a cooling zone in the continuous press. A comparative study has been done to show the advantages of using new hot pressing technology. The present model will become an important tool in the hands of wood technologist, process engineers and MDF manufacturing personnel, to better understand the internal processes and to improve production and quality of MDF boards. This theoretical model helped in developing better understanding of internal processes. By using it, we can analyse the impact of platen temperature, moisture content on the core temperature, core pressure and density profile. It gives better insight into the relationship between core pressure and delamination of the board. The model is also able to predict the internal changes in the new hot pressing technologies such as the steam injection pressing and the use of a cooling zone in a continuous press. Using the simulation results, the exact time needed for the complete curing of resin can be calculated and then these results can be applied in the commercial plants. If the pressing time is reduced, then the over all production of both batch press and continuous press will increase. The second part of the project is the development of an empirical model to correlate the physical properties from the MDF board to the mean density. The empirical model is simple and straightforward, and thus can be applied in commercial operation for control and optimization. The empirical model can predict peak density, core density, and modulus of rupture, elasticity and internal bonding within the limits in which those relationships are derived. The model gives good results for thickness ranging from 10 to 13.5 mm and density ranging from 485 kg/m³ to 718 kg/m³.
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Lilley, Susan Jane. "Digging the dirt on density : a study of medium density housing in Christchurch's Living Three zone : a thesis submitted in partial fulfillment of the requirements for the degree of Master of Arts in Geography at the University of Canterbury /." Thesis, University of Canterbury. Geography, 2006. http://hdl.handle.net/10092/1283.
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Since the 1987 Brundtland Report, the development of urban areas has been considered a key determinant in achieving 'sustainability'. Greater residential density is increasingly advocated for and applied through policy statements around the world as a way of achieving this goal. Various tiers of New Zealand government are following international policy trends, developing programmes, protocols and strategies that promote sustainability and 'good' urban design practices through intensification, or concentration, within urban areas. Research shows that a policy framework of urban concentration, through greater residential density, is only successful where consumers and providers of housing support its practical application. Confrontation between policy and the market, and the acceptability of greater levels of residential density to residents, can jeopardise a policy's success. This research uses a mix of survey and interview techniques to determine the acceptability of "medium density" developments to residents, and to understand the practises and motivations of housing developers in Christchurch's "Living 3" zone. This zone is predominantly sited between the central business district and low-density suburban areas, making it ideally located to facilitate policies of intensification. The principle purpose of the zone is the development of medium-density residential accommodation, however greater residential density is relatively new to Christchurch where the potential for expansion is seemingly unbounded. The intention of this research is to assist the planning, production and performance of future developments. In conclusion, this thesis makes recommendations to improve the form and design of medium density residential developments in Christchurch's inner Living Three zone in terms of the market's producers and consumers.
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Gatchell, Michael. "Molecular Hole Punching : Impulse Driven Reactions in Molecules and Molecular Clusters." Doctoral thesis, Stockholms universitet, Fysikum, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-129523.
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When molecules are excited by photons or energetic particles, they will cool through the emission of photons, electrons, or by fragmenting. Such processes are often thermal as they occur after the excitation energy has been redistributed across all degrees-of-freedom in the system. Collisions with atoms or ions may also lead to ultrafast fragmentation in Rutherford-like scattering processes, where one or several atoms can literally be knocked out of the molecule by the incoming projectile before the energy can be completely redistributed. The resulting fragmentation pathways can in such knockout processes be very different from those in thermal processes. This thesis covers extensive studies of collisions between ions/atoms and isolated Polycyclic Aromatic Hydrocarbon (PAH) molecules, isolated fullerene molecules, or clusters of these. The high stabilities and distinct fragmentation channels make these types of molecules excellent test cases for characterizing knockout-driven fragmentation and the reactions that these processes can lead to. I will present experimental measurements for a wide range of energies and compare them with my own molecular dynamics simulations and quantum chemical calculations. In this thesis, I present an in-depth study of the role of knockout in the energetic processing of molecules and clusters. The competition between knockout and thermally driven fragmentation is discussed in detail. Knockout-driven fragmentation is shown to result in exotic fragments that are far more reactive than the intact parent molecules or fragments from thermal processes. When such reactive species are formed within molecular clusters efficient molecular growth can take place on sub-picosecond timescales. The cluster environments are crucial here because they protect the newly formed molecules by absorbing excess energy. This is a possible pathway for the growth of large PAHs, fullerenes, and similar carbonaceous complexes found in, for instance, the interstellar medium.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 1: Submitted.