322,997 research outputs found
Orthogonal-Array based Design Methodology for Complex, Coupled Space Systems
No full textThe process of designing a complex system, formed by many elements and sub-elements interacting between each other, is usually completed at a system level and in the preliminary phases in two major steps: design-space exploration and optimization. In a classical approach, especially in a company environment, the two steps are usually performed together, by experts of the field inferring on major phenomena, making assumptions and doing some trial-and-error runs on the available mathematical models. To support designers and decision makers during the design phases of this kind of complex systems, and to enable early discovery of emergent behaviours arising from interactions between the various elements being designed, the authors implemented a parametric methodology for the design-space exploration and optimization. The parametric technique is based on the utilization of a particular type of matrix design of experiments, the orthogonal arrays. Through successive design iterations with orthogonal arrays, the optimal solution is reached with a reduced effort if compared to more computationally-intense techniques, providing sensitivity and robustness information. The paper describes the design methodology in detail providing an application example that is the design of a human mission to support a lunar base
Analisi Sperimentale dell'Interferenza Aerodinamica Ruota-Passaruota per la Vettura F131Evo
No full textReport of Depart. of Aerospace Eng. of Pisa, DDIA 2004-4, Feb. 2004
DEVELOPMENT OF MEASUREMENT METHODOLOGIES IN METROLOGY FOR CELL BIOLOGY AND REGENERATIVE MEDICINE
No full textAim of this thesis is the development of measurement methodologies in metrology for cell biology and regenerative medicine. Regenerative medicine is a novel branch of medicine based on the use of autologous stem cells and biocompatible medical devices to regenerate and repair damaged tissues of patients, i.e. by using three-dimensional scaffolds to implant stem cells into the tissue to be regenerated. Stakeholders of metrology for regenerative medicine are: health care providers who require safe, reliable and cost effective treatments, supported by evidence and approved by regulators; regulators who require standard materials and traceable data demonstrating the safety and efficacy of new products and treatments; medical products companies who require advanced and traceable techniques to develop new products and need methods to measure processes, such as cell growth on scaffolds, to ensure quality and efficiency of the medical products implanted into the patients. Consequently, regenerative medicine has the important requisite of a real time monitoring and not invasiveness neither destructiveness processes to measure the cell-scaffold interactions, in order to preserve the samples from any contamination or modification. Thus non-invasive measurement methodologies need to be developed for analysing the 3D cell culture on scaffolds and, in order to evaluate the uncertainty, highly reproducible measurement procedures are strongly required to minimize the type A uncertainties and to define the type B uncertainties. The non-invasive and non-destructive measurement of cell-scaffold interactions (i.e. stem cell proliferation and differentiation on scaffolds) is one of the most effective methodology to answer the need of testing the efficacy of the design, production/manufacturing, development and performances of stem cell-scaffold products. To satisfy the requirements and the needs for metrology in regenerative medicine, for this thesis it has been chosen to develop a measurement methodology for cellular activity (proliferation and differentiation) on 3D Biocoral® scaffolds and to conduce a metrological study to evaluate the uncertainty of the methodology. This thesis has been developed in the Bioscience group of the Italian National Metrological Institute (Istituto Nazionale di Ricerca Metrologica - INRIM). The main important contributes of this thesis to the metrology in biosciences have been: • to lay the foundations for a metrological approach to cell biology and particularly to regenerative medicine research and applications; • to address the filling of the lack of traceability in the metrology for cell biology metabolic methodologies used to evaluate cellular activities in living sample with non-invasive procedures. The main results and originalities achieved during this PhD work are: • a metabolic assay, the resazurin/resorufin assay, for the first time, has been metrologically characterized and the uncertainty of the measurement has been evaluated; • the resazurin/resorufin assay has been for the first time tailored for a 3D cell culture on Biocoral® scaffolds and the uncertainty of the measurement has been evaluated; • it was demonstrated that Biocoral® induces osteodifferentiation of stem cells and for the first time it was demonstrated on human mesenchymal stem cells; • it was demonstrated, for the first time, that the resazurin/resorufin metabolic assay can be a methodology to detect not only the proliferation but also the differentiation of stem cells on Biocoral® scaffolds; A description of the METREGEN regional project, which this thesis is part of, will follow in the introduction. The chapter 1 will give an overview on regenerative medicine field and its application with scaffolds, particularly referring to the Biocoral® scaffold. The resazurin/resorufin methodology will be deeply described in chapter 2 with a uncertainty budget evaluation and discussion. Chapter 3 will present in details a series of experiments made to establish and characterize a hMSCs in vitro 2D culture, establish a hMSCs in vitro 3D culture on Biocoral, tailor the resazurin/resorufin assay for 3D cell culture on Biocoral and evaluate the hMSCs osteodifferentiation induced by Biocoral scaffolds. All the results have been analysed with a metrological approach to evaluate the uncertainty. Finally, the conclusion will give a recapitulation and some interesting perspective of employment for the resazurin/resorufin methodology to final users, such as the cell factorie
Effect of environmental enrichment and group size on behaviour and live weight in growing rabbits
No full text[EN] The aim of this research was to study the effects of group size and environmental enrichment on behaviour and growth of 108 hybrid growing rabbits (Oryctolagus cuniculus). We compared the behaviour (time budget and reactions to specific behavioural tests: "tonic immobility" and "emergence test") and live weight of growing rabbits housed in cages with a different number of rabbits per cage (2, 3 and 4; same density:14 rabbits/m2). Half of the cages were enriched with a wooden stick (Robinia Pseudoacacia, length: 20 cm ¿ diameter: 6 cm, cylindrical) hanging from the ceiling of the cage. The stick and number of animals per cage had no effect on weight gain or on behavioural tests responses. Interaction with the stick was significantly higher at the beginning of the growing period. Principal component analysis performed on the data for the whole period showed significant differences according to the treatments: increasing the number of rabbits per cage and introducing a wooden stick seemed to affect locomotor activity frequency and social interactions. Rabbits housed 3 and 4 per cage showed less lying behaviour and higher locomotor activity and sitting. The larger functional space allowance enabled rabbits to perform more natural behaviours compared to smaller cages (2 rabbits/cage). Environmental enrichment seems to be related to higher allogrooming behaviour frequency, which could indicate a social behaviour related to pheromonal olfactory stimulation and mutual recognition.Zucca, D.; Marelli, S.; Redaelli, V.; Heinzl, E.; Cardile, H.; Ricci, C.; Verga, M.... (2012). Effect of environmental enrichment and group size on behaviour and live weight in growing rabbits. World Rabbit Science. 20(2):89-95. https://doi.org/10.4995/wrs.2012.1082SWORD899520
Modelling interference between the geogrid bearing members under pullout loading conditions
No full textThe main interaction mechanisms affecting the pullout resistance of geogrids embedded in soils are the skin friction between soil and reinforcement solid surface and the bearing resistance which develops against transversal elements. As regards bearing resistance the interference mechanism plays an important role: this can occur when the spacing between transversal members is lower than a threshold value, depending on the extensions of active and passive surfaces mobilized on bearing members. Based on the result of several large-scale pullout tests, a theoretical method to determine the peak pullout resistance of extruded geogrids embedded in a compacted granular soil is proposed. The method takes into account the interference mechanism due to the proximity of the transversal bearing members and works well for soil-geogrid interfaces in which scale effect is negligible
The influence of reinforcement geometry and confined tensile stiffness on post-cyclic pullout resistance
No full textExperimental and theoretical study on interference phenomena between the bearing members of different geogrids in pullout loading conditions.
No full textA stress transfer model to predict the pullout resistance of extruded geogrids embedded in compacted granular soils
No full textPullout tests are necessary in order to study the interaction behaviour between soil and geosynthetics in the anchorage zone, hence, the test results have direct implications in the design of reinforced soil structures. This paper presents an evaluation of the soil-geogrid interaction, conducted to quantify the contributions of the frictional and the bearing components of the pullout resistance of geogrids. Based on the data obtained by authors, a stress transfer model has been implemented to predict the results of large-scale pullout tests using the load transfer curves approach. In particular, in the proposed stress transfer model the geometry of the elements on which the bearing resistance mobilizes, the soil dilatancy effects, the geogrid extensibility and the interference phenomena (between transversal bearing members) are taken into account. The comparison between theoretical and experimental results shows a good agreement, thus confirming the reliability of the proposed approach
Analysis of the Effects of Different Underbody Exhaust Geometries in the Car Aerodynamics
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