Desarrollo de tableros aglomerados compactos de c��scara de man��. Peanuts husks compact board development

El presente proyecto de investigaci��n solicitado es continuacion de una l��nea de trabajo con insumos de desecho agroindustrial regional en la provincia de Cordoba. Prev�� aportes que contribuyan a la sustentabilidad econ��mica y social, y ambiental. Se trata de aportar valor agregado a importantes cantidades residuales de cascaras de mani. Adem��s promueve la produccion de materiales y componentes de construcci��n de viviendas saludables y accesibles para sectores con necesidades sociohabitacionales.El deshecho de c��scara de man�� constituye hoy en la provincia de C��rdoba, un recurso sobre abundante no aprovechado en la escala en que se dispone. Existen desarrollos para su aprovechamiento - camadas de aves, alimento de ganado, carbon activado- , que no alcanzan a consumir las enormes cantidades de cascaras que se disponen hoy: alrededor de 250 000 Tn/ a��o. (La produccion anual de mani en caja en la provincia de Cordoba es estimada en 700.000 Tn/a��o)A partir de los resultados ya obtenidos con paneles livianos termoaislantes, utilizados en cielorrasos y tabiques divisorios, el nuevo trabajo de investigaci��n y desarrollo se propone avanzar sobre las condiciones de produccion de tableros compactos, similares a los producidos comercialmente con residuos de la industria de la madera. Se estudiaran y experimentaran las propiedades de uso de resinas poliester, ureaformaldehido y fenolformaldehido, bajo condiciones de alta presion y temperatura. En la primera etapa (1�� a��o) buscamos obtener nuevos materiales en escala de probetas.En una etapa siguiente (2�� a��o), los nuevos materiales obtenidos ser��n aplicados al dise��o de componentes de vivienda. Se estudiar��n las posibilidades alternativas de empleo en relaci��n a los par��metros de evaluaci��n : peso, resistencia mec��nica, aislaci��n t��rmica, resistencia a la humedad, y al envejecimiento acelerado.En la ��ltima etapa (3�� a��o) los resultados obtenidos ser��n aplicados en modelos de escala real y/o prototipos demostrativos para evaluar su puesta en servicio.

An investigation into the temperature distribution resulting from cutting of compact bone using a reciprocating bone saw

Surgical procedures such as osteotomy and hip replacement involve the cutting of bone with the aid of various manual and powered cutting instruments including manual and powered bone saws. The basic mechanics of bone sawing processes are consistent with most other material sawing processes such as for wood or metal. Frictional rubbing between the blade of the saw and the bone results in the generation of localised heating of the cut bone. Research studies have been carried out which consider the design of the bone saw which deals with specifics of the saw teeth geometry and research which examines the effect of drilling operations on heating of the bone has shown that elevated temperatures will occur from frictional overheating. This overheating in localised areas is known to have an impact on the rate of healing of the bone post operation and the sharpness life of the blade. The purpose of this study was to measure the temperature at three zones at fixed intervals of 3mm, 6mm, and 9mm away from the cutting zone. It should be noted that it was the first time that this measurement technique was used to measure the temperature gradient through the bone specimen thereby establishing the extent to which clinicians are experiencing thermal injury during sawing of bone while using a reciprocating saw. The effect of various cutting feed rate on temperature elevation was also investigated in this research. The results showed that there will be a region of bone at least 9mm either side of the cutting blade experiencing thermal injury as temperatures in this region exceeded the threshold temperature of 44��C for necrosis (cell death).

Acoustic emission analysis of the effect of a 2D wedge shaped blade on the compact bone cutting process

Surgeons may use a number of cutting instruments such as osteotomes and chisels to cut bone during an operative procedure. The initial loading of cortical bone during the cutting process results in the formation of microcracks in the vicinity of the cutting zone with main crack propagation to failure occuring with continued loading. When a material cracks, energy is emitted in the form of Acoustic Emission (AE) signals that spread in all directions, therefore, AE transducers can be used to monitor the occurrence and development of microcracking and crack propagation in cortical bone. In this research, number of AE signals (hits) and related parameters including amplitude, duration and absolute energy (abs-energy) were recorded during the indentation cutting process by a wedge blade on cortical bone specimens. The cutting force was also measured to correlate between load-displacement curves and the output from the AE sensor. The results from experiments show AE signals increase substantially during the loading just prior to fracture between 90% and 100% of maximum fracture load. Furthermore, an amplitude threshold value of 64dB (with approximate abs-energy of 1500 aJ) was established to saparate AE signals associated with microcracking (41 ��� 64dB) from fracture related signals (65 ��� 98dB). The results also demonstrated that the complete fracture event which had the highest duration value can be distinguished from other growing macrocracks which did not lead to catastrophic fracture. It was observed that the main crack initiation may be detected by capturing a high amplitude signal at a mean load value of 87% of maximum load and unsteady crack propagation may occur just prior to final fracture event at a mean load value of 96% of maximum load. The author concludes that the AE method is useful in understanding the crack initiation and fracture during the indentation cutting process.

Analysis, design, optimization and realization of compact high performance printed RF filters

Magdeburg, Univ., Fak. f��r Elektrotechnik und Informationstechnik, Diss., 2010

influence of different forms of outcome information on the neural substrates of the acquisition and representation of categories

Magdeburg, Univ., Fak. f��r Naturwiss., Diss., 2012

Non compact euclidean cone 3-manifolds with cone angles less than 2���

We study of noncompact Euclidean cone manifolds with cone angles less than c&2�� and singular locus a submanifold. More precisely, we describe its structure outside a compact set. As a corol lary we classify those with cone angles & 2��/3 and those with cone angles = 2��/3.

Parametric analysis of different compact tension specimens for fracture toughness characterisation in woven composite materials

Estudi elaborat a partir d���una estada a l��� Imperial College London, entre juliol i novembre de 2006. En aquest treball s���ha investigat la geometria m��s apropiada per a la caracteritzaci�� de la tenacitat a fractura intralaminar de materials comp��sits laminats amb teixit. L���objectiu ��s assegurar la propagaci�� de l���esquerda sense que la proveta falli abans per cap altre mecanisme de dany per tal de permetre la caracteritzaci�� experimental de la tenacitat a fractura intralaminar de materials comp��sits laminats amb teixit. Amb aquesta fi, s���ha dut a terme l���an��lisi param��trica de diferents tipus de provetes mitjan��ant el m��tode dels elements finits (FE) combinat amb la virtual crack closure technique (VCCT). Les geometries de les provetes analitzades corresponen a la proveta de l���assaig compact tension (CT) i diferents variacions com la extended compact tension (ECT), la proveta widened compact tension (WCT), tapered compact tension (TCT) i doubly-tapered compact tension (2TCT). Com a resultat d���aquestes an��lisis s���han derivat diferents conclusions per obtenir la geometria de proveta m��s apropiada per a la caracteritzaci�� de la tenacitat a fractura intralaminar de materials comp��sits laminats amb teixit. A m��s, tamb�� s���han dut a terme una s��rie d���assaigs experimentals per tal de validar els resultats de les an��lisis param��triques. La concordan��a trobada entre els resultats num��rics i experimentals ��s bona tot i la pres��ncia d���efectes no previstos durant els assaigs experimentals.

A curious example of two model categories and some associated differential graded algebras

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Homotopy limits for 2-categories

We study homotopy limits for 2-categories using the theory of Quillen model categories. In order to do so, we establish the existence of projective and injective model structures on diagram 2-categories. Using these results, we describe the homotopical behaviour not only of conical limits but also of weighted limits. Finally, pseudo-limits are related to homotopy limits.

Model structures on the category of small double categories

In this paper we obtain several model structures on DblCat, the category of small double categories. Our model structures have three sources. We first transfer across a categorification-nerve adjunction. Secondly, we view double categories as internal categories in Cat and take as our weak equivalences various internal equivalences defined via Grothendieck topologies. Thirdly, DblCat inherits a model structure as a category of algebras over a 2-monad. Some of these model structures coincide and the different points of view give us further results about cofibrant replacements and cofi brant objects. As part of this program we give explicit descriptions and discuss properties of free double categories, quotient double categories, colimits of double categories, and several nerves and categorifications.

Derived categories and Grothendieck duality

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Cluster algebras, quiver representations and triangulated categories

This is an introduction to some aspects of Fomin-Zelevinsky���s cluster algebras and their links with the representation theory of quivers and with Calabi-Yau triangulated categories. It is based on lectures given by the author at summer schools held in 2006 (Bavaria)and 2008 (Jerusalem). In addition to by now classical material, we present the outline of a proof of the periodicity conjecture for pairs of Dynkin diagrams (details will appear elsewhere) and recent results on the interpretation of mutations as derived equivalences.

On the homotopy theory of spectral categories

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A Thomason model structure on the category of small n-fold categories

We construct a cofibrantly generated Thomason model structure on the category of small n-fold categories and prove that it is Quillen equivalent to the standard model structure on the category of simplicial sets. An n-fold functor is a weak equivalence if and only if the diagonal of its n-fold nerve is a weak equivalence of simplicial sets. We introduce an n-fold Grothendieck construction for multisimplicial sets, and prove that it is a homotopy inverse to the n-fold nerve. As a consequence, the unit and counit of the adjunction between simplicial sets and n-fold categories are natural weak equivalences.