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Effettualità in un nuovo mercato. Trasformazioni urbane, fondi immobiliari e nuove culture di progetto
No full textLa tesi individua come tema generale di ricerca le trasformazioni urbane innescate attraverso l'ausilio di strumenti di finanza immobiliare e più specificamente tramite i fondi d'investimento ad apporto. Questo interesse nasce dalla volontà, già nelle fasi embrionali della ricerca, di identificare un ambito d'indagine nel quale il progetto potesse essere potenzialmente decisivo nel ciclo economico post-crisi. La recessione conseguente allo scoppio della bolla immobiliare negli Stati Uniti a partire dal 2007, la cosiddetta "Great recession" , ha avuto proporzioni tali da rappresentare un vero e proprio spartiacque degli ultimi decenni. Identificando quindi tale cesura storica, la ricerca muove dall'analisi della condizione urbana italiana nel periodo che la precede analizzando condizioni economiche e politiche di sviluppo urbano, e si interroga successivamente su quali possano essere le dinamiche determinanti all'indomani di questa. Come vedremo, la tesi sostiene che gli strumenti di finanza immobiliare applicati ai processi di valorizzazione del patrimonio pubblico contengono nella loro struttura potenzialità tali da candidarli, nonostante i puntuali insuccessi, ad una forte affermazione nel prossimo ciclo economico. Da un punto di vista disciplinare, la ricerca si pone l'obiettivo di determinare quale possa essere il ruolo del progetto all'interno di queste dinamiche finanziarie. Ulteriormente, avendo rilevato in molti casi l'inefficienza delle tattiche di costruzione della legittimità progettuale, ci si interroga su quale possa essere un modo per reinterpretare il progetto, creando un nuovo modello operante che determini una maggiore capacità di produrre effetti da parte del progetto nel ciclo economico post-crisi
FEM simulations and rotation capacity evaluation for RHS temper T4 aluminium alloy beams
No full textThe aim of this work is the development of an empirical relationship for evaluating the rotation capacity of RHS temper T4 aluminium alloy beams subjected to non-uniform bending. The proposed relationships are based on the numerical results coming from an extensive parametric analysis performed by means of FE code ABAQUS, which gains insight into the influence of all the geometrical and mechanical parameters affecting the ultimate behaviour of aluminium alloy beams. In particular, the influence of the flange slenderness, the influence of the web restraining effect related to the flange-to-web slenderness ratio and the influence of the moment gradient are investigated. The modelling of the material is carried out by adopting the constitutive law proposed by Eurocode 9, based on the Ramberg-Osgood model whose shape factor characterises the hardening behaviour of the material. The investigations concern these factors considered separately as well as their interaction. The results are herein reported with reference to temper T4, i.e. an alloy characterised by a significant hardening behaviour, and show the importance of some of the investigated parameters on the maximum flexural resistance, corresponding to the complete development of local buckling of compressed flange, and on the rotation capacity of aluminium alloy beams. Successively, by means of monovariate and multivariate non linear regression analyses, empirical relationships are provided in order to predict both the ultimate bending resistance and the rotation capacity of RHS temper T4 aluminium alloy beams starting from their geometrical and mechanical properties
Thermal hydraulic analysis of a passively controlled DHR system
No full textThe safe operation of nuclear reactors cooled by liquid metal is an important issue to be addressed for the development of nuclear technology and presents specific aspects related to the properties of the coolant. While the main parameters influencing safety for water-cooled reactors are reasonably well known, DHR systems for reactors cooled by liquid metal present additional challenges related to coolant freezing, since solidification temperature is higher than the temperature of the final heat sink. If the primary coolant solidifies obstructions of the primary flow path can occur, inhibiting natural circulation and core cooling. This paper presents an innovative passive safety system for decay heat removal which passively delays the coolant freezing. The system adopts noncondensable gases to passively control the power removed from the primary system and to delay freezing in the long term while keeping primary system temperatures below an acceptable limit. The system is simulated by means of the Relap5-3D computer code for a loss of offsite power of the innovative lead-cooled reactor ALFRED. A sensitivity analysis has been carried out in order to study the effect of noncondensable gas pressure on the performance of the passive decay heat removal system, and in particular on the primary coolant temperatures
Frictional effects in structural behavior of noend-connected steel jacketed RC columns: Experimental results and new approaches to model numerical and analytical response
No full textSteel jacketing of reinforced concrete (RC) columns is a common retrofitting technique used to restore bearing and deformation capacity of buildings presenting structural deficiencies. For practical reasons, steel angles are in several cases arranged leaving a gap with the end beams or slabs. Despite this disconnection, the angles are still able to support a non-negligible portion of load because of the frictional forces developed along the column-angle contact interface. In these cases, the definition of computational numerical and analytical models for the assessment of reinforced cross sections becomes more complex and must be handled with care. The actual load-carrying capacity of the angles is a function of lateral confinement pressure, cohesive strength, and the friction coefficient between the materials. This paper presents first the results of an original experimental campaign on RC column specimens with and without steel jacketing subjected to compressive axial and eccentric tests. Subsequently, a new approach is proposed to define a plane fiber-section model of the reinforced cross section accounting for the frictional action occurring along the column-angle interfaces. An equivalent stress-strain constitutive model for the angles is calibrated and validated through comparison with experimental results. Finally, a simple analytical stress-block procedure to derive continuous and simplified axial force bending moment domains is illustrated as a method for the hand-verification of reinforced cross sections
Surface EMG and muscle fatigue: multi-channel approaches to the study of myoelectric manifestations of muscle fatigue
No full textIn a broad view, fatigue is used to indicate a degree of weariness. On a muscular level, fatigue posits the reduced capacity of muscle fibres to produce force, even in the presence of motor neuron excitation via either spinal mechanisms or electric pulses applied externally. Prior to decreased force, when sustaining physically demanding tasks, alterations in the muscle electrical properties take place. These alterations, termed myoelectric manifestation of fatigue, can be assessed non-invasively with a pair of surface electrodes positioned appropriately on the target muscle; traditional approach. A relatively more recent approach consists of the use of multiple electrodes. This multi-channel approach provides access to a set of physiologically relevant variables on the global muscle level or on the level of single motor units, opening new fronts for the study of muscle fatigue; it allows for: (i) a more precise quantification of the propagation velocity, a physiological variable of marked interest to the study of fatigue; (ii) the assessment of regional, myoelectric manifestations of fatigue; (iii) the analysis of single motor units, with the possibility to obtain information about motor unit control and fibre membrane changes. This review provides a methodological account on the multi-channel approach for the study of myoelectric manifestation of fatigue and on the experimental conditions to which it applies, as well as examples of their current applications
Cacce, loisir, territori e impianti radiali: Stupingi tra Regno di Sardegna ed Europa
No full textL'assetto radiale delle rotte di caccia nei territori boscati ha spesso influito sull'impianto architettonico delle residenze e dei casini venatori in Europa. La Palazzina di caccia di Stupinigi, realizzata da Filippo Juvarra nel 1729 è un episodio "alto" all'interno di una sequenza di lunga durata che - specialmente in area tedesca - sulla base delle invenzioni di Carlo Fontana (progetto di edificio in villa, 1689) e di Johann Bernhard Fischer von Erlach (palazzo Althan a Rossau, 1693) per "palazzi di villa", e del folgorante progetto dello stesso Juvarra per il concorso clementino del 1705 (Regio Palazzo di Villa per il diporto di tre Personaggi) si dipana tra i casi della Malgrange (Jacques Germain Boffrand, 1712) presso Nancy, Karlsruhe (Jacob Friedrich von Betzendorf, 1715) e Clemenswerth (Johann Conrad Schlaun, 1737) in Germania, Ozora (József Liptai, 1760) e Nagykaroly (Franz Rosenstingl, 1783) in Ungheria. Si tratta di casi in cui la compenetrazione tra forma, funzione, territorio e paesaggio costituiscono casi emblematici del respiro a grande scala dell'architettura tardobarocca in Europa
Potentialities of Boot Injection Combined with After Shot for the Optimization of Pollutant Emissions, Fuel Consumption and Combustion Noise in Passenger Car Diesel Engines
No full textThe present paper illustrates an investigation about the potentialities of injection rate shaping coupled with an after injection. A pilot shot can either be absent or present before the rate-shaped boot injection. The experimental tests have been performed on a partial PCCI Euro 5 diesel engine endowed with direct-acting piezoelectric injectors. Starting from optimized triple pilot-main-after injection strategies, boot injection was implemented by maintaining the direct-acting piezo injector needle open at part lift. The results of two steady state working conditions have been presented in terms of engine-out emissions, combustion noise and brake specific fuel consumption. In addition, in-cylinder analyses of the pressure, heat-release rate, temperature and emissions have been evaluated. Considering the in-cylinder pressure traces and the heat release rate curves, the injection rate shaping proved to influence combustion in the absence of a pilot injection to a great extent. A pilot shot, added before the boot injection, determined a mitigation of the influence of rate shaping. A simultaneous reduction in NOx and soot can be achieved for small quantities of fuel injected during boot injection, compared to the optimized triple injection strategies. However, a trade-off exists between emissions and combustion noise when boot injection is applied. On the other hand, the variations in bsfc were only minor. The advantages of the application of boot injection are greater for low to medium loads than for medium to high loads. However, it was not possible to find a working condition in which boot injection provided simultaneous advantages on emissions, noise and consumption, compared to the optimized triple injection
A multi-stage triaxial testing procedure for low permeable geomaterials applied to Opalinus Clay
No full textIn many engineering applications, it is important to determine both effective rock properties and the rock behavior which are representative for the problem's in situ conditions. For this purpose, rock samples are usually extracted from the ground and brought to the laboratory to perform laboratory experiments such as consolidated undrained (CU) triaxial tests. For low permeable geomaterials such as clay shales, core extraction, handling, storage, and specimen preparation can lead to a reduction in the degree of saturation and the effective stress state in the specimen prior to testing remains uncertain. Related changes in structure and the effect of capillary pressure can alter the properties of the specimen and affect the reliability of the test results. A careful testing procedure including back-saturation, consolidation and adequate shearing of the specimen, however, can overcome these issues. Although substantial effort has been devoted during the past decades to the establishment of a testing procedure for low permeable geomaterials, no consistent protocol can be found. With a special focus on CU tests on Opalinus Clay, this study gives a review of the theoretical concepts necessary for planning and validating the results during the individual testing stages (saturation, consolidation, and shearing). The discussed tests protocol is further applied to a series of specimens of Opalinus Clay to illustrate its applicability and highlight the key aspects
Statistical inference of the relations among air temperature, land-use change, and rockfall hazard
No full textClimate change has widespread impacts on human and natural systems worldwide. The pronounced air temperature warming detected worldwide could explain unusual events, as for example the increment of extreme precipitation events, increased incidence of summer heatwaves and slope instability. The possible presence of non-climatic forcings affecting temperature records, as for example land-use and land-cover changes, could introduce significant bias in the records and uncertainty on global overall temperature trends. This could somehow alterate, on the one hand, the perception of global warming, and on the other hand, all temperature-related analyses and models. Nevertheless, a robust assessment of climate warming patterns entails not only the analysis of all climate variables involved, but also the full understanding of the impacts on the natural systems, as for example the cryosphere, that could be used as terrestrial indicators of climate change. Chapter 1 shed light on the main scientific question investigated in the thesis, presenting the proposed investigation strategy, and the techniques applied. After an introduction on the issue of increasing air temperature vaiability in the current context of climate change, the two macrotopics of the thesis are presented and briefly outlined (Chapter 2 and 3). In Chapter 2, we investigate the nexus between temperature variations and urbanization trends, by analysing data recorded from weather instruments worldwide. After an extended introduction on the Urban Heat Island effect and its implications for climate warming trends at regional and global scale, we propose several methods to investigate the presence of a possible relation between air temperature variations and urbanizations dynamics with time, based on nightlights satellite measurements as proxy of urbanization. We applied a global scale analysis on more than 5000 temperature stations from the Berkeley Earth dataset in the period 1992-2013. Results highlight the tendency of urbanization to affect temperature trend at continental and regional scales. Significant positive concordant trends in temperature and nightlights variations have been detected, especially in developing and emerging regions, where the effects of growing urbanization are more evident. In Chapter 3 we turn to investigate the effects of air temperature variations on the hydrogeological hazard risk in those environments that are among the most sensitive to climate change, i.e. the high elevation sites. In alpine areas, and in particular in high mountain areas, the potential effects of environmental changes on air temperature data are minimum, since these areas are only slightly affected by urbanization dynamics and land-use changes. More in detail, in Chapter 3, we propose a statistical-based tool for the detection of the role of temperature, in association with other climate-related variables (as precipitation), in the triggering of slope stability. This approach is aimed to point out the potential climatic triggering climate factors for the slope failure. It has thought up as a tool for a better comprehension of the possible effects of air temperature variations on environmental dynamics, also in the presence of sparse and poor-quality data. We performed this method on a catalogue of 41 rockfalls in the Italian Alps, focusing on the role of temperature on slope instability preparation and initiation, and on cryosphere-related dynamics. The final purpose is detecting a possible linkage between slope failures and meteorological anomalies, and results suggest a major role of temperature as a preparatory/triggering factor. Rockfalls occurred in association with significant temperature anomalies in 83% of our case studies, and different regional patterns emerge from the data. Based on these results, temperature can be considered as a key factor contributing to slope failure occurrence in different ways, in presence of both warm and cool temperature anomalies. Chapter 4 presents a critical analysis in terms of how much it could be really answered of the main scientific questions with this work, what are the limitations encountered, which questions remain open and the possible further developments