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A Comparison between 3D Printing and Milling Process for a Spar Cap Fitting (Wing-fuselage) of UAV Aircraft
No full textTopology optimization is playing an important role in the aircraft design. The demand of lower fuel consumption reflects on the optimization of the airframe of flying vehicles to reduce the structure weight, therefore improving the fraction of the payload. This work focuses on the replacement of an existing part (spar cap fitting) with the new topologically optimized part to be manufactured with 3D printing (Selective Laser Sintering -SLS). The manufacturing constraints (minimum dimension, growth orientation) influence on the optimal results is evaluated to compare traditional milling process' performance with the new SLS technique
A dataflow-oriented modeling approach to business processes
No full textThis paper presents a dataflow-oriented modeling approach (called DMA) targeted at business processes that operate on the entities forming an information system. The approach promotes the integration between business processes and information systems in that process models result from the interconnection of tasks and dataflow nodes. The latter denote flows of business entities of the same type and state. The entity types along with their relationships and attributes are shown in a companion information model. DMA leverages the dataflow to represent human decisions, which may concern the selection of the input entities when a task needs more than one, and the selection of the task with which to handle the input entities when two or more tasks are admissible. An example related to an order handling process illustrates the representation of human choices. DMA process models build on the artifact-oriented approach in that they combine the life cycles of the business entities involved. The life cycles can be separated and this facilitates the comparison with reference models. A major contribution of the paper is the presentation of the extraction algorithm which provides the separated life cycles
One dimensional photonic crystal for label-free and fluorescence sensing application
No full textThe development of more sensitive and more reliable sensors aids medical applications in many fields as diseases detection or therapy progress. This thesis threats the development of an optical biosensor based on electromagnetic modes propagating at the interface between a finite one-dimensional photonic crystal (1DPC) and a homogeneous external medium, also named Bloch Surface Waves (BSW). BSW have emerged as an attractive approach for label-free sensing in plasmon-like sensor configurations. Besides label-free operation, the large field enhancement and the absence of quenching allow the use of BSW to excite fluorescent labels that are in proximity of the 1DPC surface. This approach was adapted to the case of angularly resolved resonance detection, thus giving rise to a combined label-free/labelled biosensor platform. BSW present many degrees of design freedomthat enable tuning of resonance properties. In order to obtain a figure of merit for an optimization, I investigated the measurement uncertainty depending on resonance width and depth with different numericalmodels. This has led to a limit of detection that can assist the choice of the best design to use. Two tumor biomarkers, such as vascular endothelial growth factor (VEGF) and Angiopoietin-2 (Ang2), have been considered to be detected with the BSW biosensing platform. For this purpose the specific antibodies for the two tumor biomarkers were immobilized on the 1DPC biochip surface. The conclusive experiments reported in this work demonstrated the successful detection of the VEGF biomarker in complex matrices, such as cell culture supernatants and human plasma samples. Moreover, the platformwas used to determinate Ang2 concentration in untreated human plasma samples using low volumes, 300 μL, and with short turnaround times, 30 minutes. This is the first BSW based biosensor assay for the determination of tumor biomarker in human plasma samples at clinically relevant concentrations
Effective Mitigation of Radiation-induced Single Event Transient on Flash-based FPGAs
No full textDue to the decreasing feature sizes of VLSI circuits, radiation induced Single Event Transients (SETs) are increasingly dominating the event ratio on modern VLSI devices. In particular, Flash-based FPGAs are characterized by the main concern of radiation-induced voltage glitches or SETs in the combinational logic. Transient pulses can be sampled by a storage element and can propagate through the circuit up to the outputs and leading to an error. In this paper, we propose a complete implementation flow including sensitivity analysis, fault tolerant mapping and fault tolerance-oriented place and route for the effective design of SET tolerant circuits on Flash-based FPGAs. In details, the proposed method allows accurate measurement of the transient pulse source induced by radiation particles and estimation of the SET error rate on the overall circuit. Besides the developed method provides a netlist mapping and place and route tool for the selective mitigation of SET effects. The proposed method has been applied to an industrial design oriented to the Euclid European Space Agency mission including more than ten different modules. The obtained results show an improvement of the total filtering capability of around 43 times with respect to the original netlist without affecting the timing constraints of the circuit
Experimental evidence of Fano resonances in nanomechanical resonators
No full textFano resonance refers to an interference between localized and continuum states that was firstly reported for atomic physics and solid-state quantum devices. In recent years, Fano interference gained more and more attention for its importance in metamaterials, nanoscale photonic devices, plasmonic nanoclusters and surface-enhanced Raman scattering (SERS). Despite such interest in nano-optics, no experimental evidence of Fano interference was reported up to now for purely nanomechanical resonators, even if classical mechanical analogies were referred from a theoretical point of view. Here we demonstrate for the first time that harmonic nanomechanical resonators with relatively high quality factors, such as cantilevers vibrating in vacuum, can show characteristic Fano asymmetric curves when coupled in arrays. The reported findings open new perspectives in fundamental aspects of classical nanomechanical resonators and pave the way to a new generation of chemical and biological nanoresonator sensors with higher parallelization capability
Ultimate behaviour of RHS temper T6 aluminium alloy beams subjected to non-uniform bending: Parametric analysis
No full textThe aim of this work is the numerical assessment of the ultimate behaviour of temper T6 aluminium alloy beams subjected to non-uniform bending. An extensive numerical analysis has been performed by means of FE code ABAQUS with reference to RHS sections considering the typical range of variation of the geometrical parameters governing the ultimate behaviour of RHS beams under non-uniform bending. In particular, a wide parametric analysis has been carried out by varying the flange slenderness, the flange-to-web slenderness ratio and the non-dimensional shear length accounting for the moment gradient. The ultimate behaviour of such beams has been investigated with reference to the material constitutive law proposed by Eurocode 9, based on the Ramberg-Osgood model. Particular attention has been devoted to the interaction between the different non-dimensional parameters governing the ultimate behaviour. The importance of the investigated parameters on the non-dimensional ultimate flexural strength and on the rotation capacity of aluminium alloy beams is clearly pointed out. Successively, by means of multivariate non linear regression analyses, empirical relationships are provided in order to predict both the non-dimensional ultimate flexural resistance and the rotation capacity of RHS temper T6 aluminium alloy beams, starting from their geometrical and mechanical properties
Fitness: Sheep-wool and Hemp Sustainable Insulation Panels
No full textFITNESs, Fibre Tessili Naturali per l'Edilizia Sostenibile (Natural Textile Fibers for Sustainble Building), is a research project concerning an experimental hemp and sheep wool insulation panel. The new panel has two main innovative features: unlike the already existing hemp and wool insulation mats, it is a semi-rigid product and it has a low environmental impact, as shown by the Life Cycle Assessment. FITNESs panels are particularly suitable for eco-building sector, they are 100% natural, recyclable and made with by-products from local production chains (Piemonte Region). The paper presents the results of thermal conductivity, acoustic absorption coefficient and thermal transmittance of an experimental wall measurements, in order to demonstrate the effectiveness of FITNESs panels as an insulation product for buildings
DIGITAL INVASIONS: FROM POINT CLOUDS TO HISTORICAL BUILDING OBJECT MODELING (H-BOM) OF A UNESCO WHL SITE
No full textThe paper here presented shows the outcomes of a research/didactic activity carried out within a workshop titled "Digital Invasions. From point cloud to Heritage Building Information Modeling" held at Politecnico di Torino (29th September - 5th October 2016). The term digital invasions refers to an Italian bottom up project born in the 2013 with the aim of promoting innovative digital ways for the enhancement of Cultural Heritage by the co-creation of cultural contents and its sharing through social media platforms. At this regard, we have worked with students of Architectural Master of Science degree, training them with a multidisciplinary teaching team (Architectural Representation, History of Architecture, Restoration, Digital Communication and Geomatics). The aim was also to test if our students could be involved in a sort of niche crowdsourcing for the creation of a library of H-BOMS (Historical-Building Object Modeling) of architectural elements
Biomacromolecules: A sustainable approach for the design of fire retardants for textiles
No full textTextiles are very hazardous materials when related to fires, because of the high surface to mass ratio and the open structure, which simplify the contact with heat and oxygen. Fabrics have a great impact on the development of fatal fires because of their easy ignition and high burning rate. For the flame retardancy of fabrics several strategies have been developed throughout the years, and nowadays additives and reagents are widely used for the different kinds of textiles. The most common commercial durable finishes for cotton fabrics contain phosphorous and nitrogen compounds. These products have been predominant in the field of flame retardants for cotton for 50 years, but recently the request for a reduction of environmental impact and of formaldehyde release during manufacturing and utilisation have pushed researchers towards new kinds of finishing. This Ph.D. work aimed at investigating the effectiveness and the possibilities of the use of biomacromolecules as fire retardants for cellulosic textiles (i.e. cotton). To this aim, three biomacromolecules were taken in consideration: whey proteins, caseins and nucleic acids. Whey proteins and caseins, derived from milk, were applied on cotton fabrics and their thermal and thermo-oxidative stability and fire behaviour were assessed through thermogravimetric analysis, cone calorimetry and horizontal flame spread tests. These biomacromolecules were effective in improving the fire retardancy of the treated fabrics, slowing down the combustion rate in flame spread tests and favouring the formation of a coherent carbonaceous residue (char). Then, the fire retardant behaviour of DNA was thoroughly investigated. First, commercially-available DNA from herring sperm and testes, having different molecular weights, were applied on cotton fabrics: the experimental parameters (i.e., molecular weight of the biomacromolecules, pH of the aqueous solution, number of impregnations needed for achieving the final dry add-on on the treated fabrics) were optimized in order to achieve the highest flame retardant effectiveness. The distribution of the nucleic acids on the underlying fabric was studied through SEM analyses. Thermogravimetric analyses, cone calorimetry and horizontal flame spread tests were carried out for assessing the thermal and thermo-oxidative stability and the fire behaviour of the treated fabrics. In detail, the low-molecular-weight DNA solution prepared either at pH 4 or 8 and applied on cotton with multiple impregnation steps was the most effective flame retardant treatment. Pursuing the research, the problem related to the high cost of commercially available DNA was considered: to overcome this drawback, a novel extraction method, starting from exhausted biomasses or agro-food crops, was developed. This method focused on the extraction of high quantities of nucleic acids, exploiting a low environmental impact approach. Overall, the recovered nucleic acids showed a fire behaviour similar to that of commercially-available counterparts. Finally, the washing fastness of the cotton fabrics treated with the biomacromolecules was considered: in fact, all the selected biomacromolecules are waterborne systems, which easily come off the fabrics when subjected to washing cycles, even in hot water only. This issue was taken on by treating cotton fabrics with nucleic acids and chitosan in mixture or as separate layers and also exploiting the layer by layer technique. The washing fastness of the treated fabrics was significantly improved by subjecting them to UV-curing, thus achieving the grafting of chitosan on cotton and, at the same time, entrapping the nucleic acid in the grafted chitosan coating. Notwithstanding the achieved fire retardancy, the fabrics treated with chitosan and nucleic acids also showed an antibacterial activity, due to the presence of chitosan. Furthermore, 30 bilayers of nucleic acids and chitosan provided the fabrics with self-extinction, either before and after a water washing cycle at 55°C. As far as the effectiveness of the treatments is concerned, all the selected biomacromolecules conferred fire retardant features to cotton fabrics. In particular, low-molecular-weight nucleic acids and caseins were the most performing biomacromolecules either in forced combustion or in flame spread tests. Cotton fabrics treated with nucleic acids or caseins were able to achieve self-extinction in horizontal flame spread tests, with a reduction of the burning rate and an increase of the residue left. Similar reductions in the HRR were also observed in cone calorimetry tests. The suggested approach is quite simple and does not involve the use of particular chemicals or expensive equipment; furthermore, the selected biomacromolecules are soluble/dispersible in water. In conclusion, the proposed flame retardants for cotton may represent a new sustainable approach to face the challenges related to the increasing awareness of the health and environmental impact of traditional products and processes