103 research outputs found

    Between City and Nature Grammars for the Urban Form

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    This abstract refers to theoretical and application research on the grammars of urban form that the author is carrying on into Urban and Architecture Design courses in dICAR Department of the Polytechnic of Bari and other design experience as the International Workshop Erasmus Intensive Programme "Re_Build The Urban Form" held in Monopoli (Bari) in 2013. The crisis of the contemporary city represents the occasion to redefine its form beginning from an idea of the city in which the relationship between the form of the land and form of urban settlements is recognized as a fundamental value. Disused urban areas have a central role in the process of "re-generation" of the form of the city for re-founding potentialities that these empty, wide and central space may have in the process of renovatio urbis. Compared to this problematic field, our disciplinary contribution is developed in terms of "form", both theoretical, individualizing in the idea of “city-territory” the field of application of the research, then from a design point of view, assuming an episteme able to recognize in distinguished way the morphological value of landscape and urban settlements. Case study cities are represented by Gravina and Monopoli, medium-size cities in South of Bari (Apulia-Italy). Identified project sites are crisis areas of urban form, connoted by the presence of abandoned buildings and empty unresolved spaces; they have a great value for the proximity to the ancient "compact" city and for the strong relation with natural excellence elements such as ravin and natural harbour on the coast-line. The aim of this work, both theoretical then didactic, is defining and new settlement/dwelling models as paradigms of a new idea of city-territory, using formal grammars of exemplary methodological value, able to express a meaningful relationship between the form of the land and the urban form

    Organic and Mineral Fertilisation of Temporary Grassland

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    In Italy, the need to reduce the application of chemical fertilisers and to dispose of different kinds of bio-wastes (municipal solid waste (MSW), olive mill waste, distiller\u27s grains) has led to more compost being made from these materials. Since 1995 our Institute has carried out several studies on different crops. The results obtained so far for grain and industrial crops (Montemurro et al., 2003; Maiorana et al., 2004) appear very interesting. But rarely have the composts been applied to fodder crops. Therefore, this research is aimed to evaluate the effect of MSW-compost on temporary grassland of cocksfoot (Dactylis glomerata) and of lucerne, (Medicago sativa) in Southern Italy (Apulia Region)

    Variable-stiffness composites optimisation under multiple design requirements and loads

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    The aim of this paper is twofold. On the one hand, it presents a methodology for the deterministic optimisation of a general class of variable-stiffness composite (VSC) structures, including a solution obtained by using laminæ with a curvilinear fibres-path and variable-thickness, by considering different design requirements under multiple load cases. The considered framework is the multi-level design methodology based on the polar parameters (PPs) to describe the macroscopic behaviour of the VSC structure. Particularly, only the first-level problem is addressed in this work: the design variables are, thus, the PPs and the thickness of the VSC laminate, whose spatial distribution is described via basis spline (B-spline) surfaces. The goal is to minimise the mass of the VSC structure subject to design requirements on feasibility, strength, first buckling load and maximum curvature of the fibres-path. This latter is formulated as an equivalent (conservative) constraint in the PPs space, regardless of the fibres-path within each lamina. Moreover, a general formulation of the gradient of the requirements related to buckling load and strength is proposed, which takes advantage from the main properties of B-spline entities and PPs. On the other hand, this paper aims to propose a new benchmark problem that is representative of a panel belonging to the fuselage of a standard civil aircraft subjected to multiple loading conditions. To this end, a wide campaign of numerical tests has been performed by considering a sensitivity analysis of the optimised solution to: (a) the integer parameters involved in the definition of the B-spline entities describing the distribution of the PPs and, possibly, of the thickness, (b) the type of VSC structure, (c) the type of deterministic optimisation algorithm. The results can be used as a database to assess the effectiveness of different design strategies against the optimised solutions presented in this paper

    A general isogeometric polar approach for the optimisation of variable stiffness composites: Application to eigenvalue buckling problems

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    This study presents a general approach for the multi-scale design of variable stiffness composites (VSCs). The first-level problem of the multi-scale two-level optimisation strategy (MS2LOS) is solved to determine the optimal distribution of the VSC stiffness properties at the macroscopic scale satisfying the requirements of the problem at hand. In this phase, the VSC laminate is modelled as an equivalent homogeneous anisotropic plate whose behaviour is described in terms of polar parameters (PPs), which vary locally over the structure. The First-order Shear Deformation Theory is used to take into account the influence of the transverse shear stiffness on the mechanical response of the VSC and Basis Spline (B-Spline) surfaces are employed to represent the PPs fields. In this background, the expression of the gradient of the buckling factor is determined analytically by exploiting the properties of the polar formalism and of the B-Spline surfaces. Moreover, the effect of the discrete variables, involved in the definition of the B-Spline surfaces, on the performances of the optimised solution is investigated. The effectiveness of the approach is proven on two benchmark problems dealing with the maximisation of the first buckling load of a VSC laminate, subject to feasibility and geometric requirements, taken from the literature. The results obtained by means of the MS2LOS based on the polar formalism outperform those reported in the literature, which are obtained through an optimisation strategy based on lamination parameters

    A multi-scale two-level optimisation strategy integrating a global/local modelling approach for composite structures

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    In this work, a multi-scale optimisation strategy for the preliminary design of composite structures involving design requirements at different scales, is presented. Such a strategy, denoted as GL-MS2LOS, has been formulated by integrating a dedicated global-local (GL) modelling approach into the multi-scale two-level optimisation strategy (MS2LOS). The GL-MS2LOS aims at proposing a very general formulation of the design problem, without introducing simplifying hypotheses and by considering, as design variables, the full set of geometric and mechanical parameters defining the behaviour of the composite structure at each pertinent scale. By employing a GL modelling approach, most of the limitations of well-established design strategies based on analytical or semi-empirical models are overcome. The effectiveness of the presented GL-MS2LOS is proven on a meaningful study case: the least-weight design of a composite fuselage barrel of a wide-body aircraft undergoing various loading conditions and subject to requirements of different nature. Fully parametric global and local FE models are interfaced with an in-house metaheuristic algorithm to perform the optimisation. Refined local FE models are created only for critical regions of the structure, automatically detected during the global analysis, and linked to the global one thanks to the implementation of a sub-modelling approach. The whole process is completely automated and, once set, it does not need any further user intervention. The general nature of the GL-MS2LOS allows finding an optimised configuration characterised by a weight saving of 40% when compared to an optimised aluminium solution obtained through a similar GL optimisation strategy.Project PARSIFAL (Prandtlplane ARchitecture for the Sustainable Improvement of Future AirpLanes), Grant Agreement n.723149

    Multi-scale optimisation of thin-walled structures by considering a global/local modelling approach

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    In this work, a design strategy for optimising thin-walled structures based on a global-local finite element (FE) modelling approach is presented. The preliminary design of thin-walled structures can be stated in the form of a constrained non-linear programming problem (CNLPP) involving requirements of different nature intervening at the different scales of the structure. The proposed multi-scale optimisation (MSO) strategy is characterised by two main features. Firstly, the CNLPP is formulated in the most general sense by including all design variables involved at each pertinent scale of the problem. Secondly, two scales (with the related design requirements) are considered: i) the structure macroscopic scale, where low-fidelity FE models are used; ii) the structure mesoscopic scale (or component-level), where more accurate FE models are involved. In particular, the mechanical responses of the structure are evaluated at both global and local scales, avoiding the use of approximated analytical methods. The MSO is here applied to the least-weight design of an aluminium fuselage barrel of a wide-body aircraft. Fully parametric global and local FE models are interfaced with an in-house metaheuristic algorithm. Refined local FE models are created only for critical regions of the structure, automatically detected during the global analysis, and linked to the global one thanks to the implementation of a sub-modelling approach. The whole process is completely automated and, once set, it does not need any further user intervention.This paper presents part of the activities carried out within the research project PARSIFAL (Prandtlplane ARchitecture for the Sustainable Improvement of Future AirpLanes), which has been funded by the European Union under the Horizon 2020 Research and Innovation Program (Grant Agreement n.723149

    Blood Transfusions and Adverse Events after Colorectal Surgery: A Propensity-Score-Matched Analysis of a Hen-Egg Issue

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    Blood transfusions are considered a risk factor for adverse outcomes after colorectal surgery. However, it is still unclear if they are the cause (the hen) or the consequence (the egg) of adverse events. A prospective database of 4529 colorectal resections gathered over a 12-month period in 76 Italian surgical units (the iCral3 study), reporting patient-, disease-, and procedure-related variables, together with 60-day adverse events, was retrospectively analyzed identifying a subgroup of 304 cases (6.7%) that received intra- and/or postoperative blood transfusions (IPBTs). The endpoints considered were overall and major morbidity (OM and MM, respectively), anastomotic leakage (AL), and mortality (M) rates. After the exclusion of 336 patients who underwent neo-adjuvant treatments, 4193 (92.6%) cases were analyzed through a 1:1 propensity score matching model including 22 covariates. Two well-balanced groups of 275 patients each were obtained: group A, presence of IPBT, and group B, absence of IPBT. Group A vs. group B showed a significantly higher risk of overall morbidity (154 (56%) vs. 84 (31%) events; OR 3.07; 95%CI 2.13-4.43; p = 0.001), major morbidity (59 (21%) vs. 13 (4.7%) events; OR 6.06; 95%CI 3.17-11.6; p = 0.001), and anastomotic leakage (31 (11.3%) vs. 8 (2.9%) events; OR 4.72; 95%CI 2.09-10.66; p = 0.0002). No significant difference was recorded between the two groups concerning the risk of mortality. The original subpopulation of 304 patients that received IPBT was further analyzed considering three variables: appropriateness of BT according to liberal transfusion thresholds, BT following any hemorrhagic and/or major adverse event, and major adverse event following BT without any previous hemorrhagic adverse event. Inappropriate BT was administered in more than a quarter of cases, without any significant influence on any endpoint. The majority of BT was administered after a hemorrhagic or a major adverse event, with significantly higher rates of MM and AL. Finally, a major adverse event followed BT in a minority (4.3%) of cases, with significantly higher MM, AL, and M rates. In conclusion, although the majority of IPBT was administered with the consequence of hemorrhage and/or major adverse events (the egg), after adjustment accounting for 22 covariates, IPBT still resulted in a definite source of a higher risk of major morbidity and anastomotic leakage rates after colorectal surgery (the hen), calling urgent attention to the implementation of patient blood management programs

    Sourdough fermented breads are more digestible than those started with baker’s yeast alone. An in vivo challenge dissecting distinct gastrointestinal responses

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    As a staple food, bread digestibility deserves a marked nutritional interest. Combining wide-spectrum characterization of breads, in vitro nutritional indices, and in vivo postprandial markers of gastrointestinal function, we aimed at comparing the digestibility of sourdough and baker’s yeast breads. Microbiological and biochemical data showed the representativeness of the baker´s yeast bread (BYB) and the two sourdough breads (SB and t-SB, mainly differing for the time of fermentation) manufactured at semi-industrial level. All in vitro nutritional indices had the highest scores for sourdough breads. Thirty-six healthy volunteers underwent an in vivo challenge in response to bread ingestion, while monitoring gallbladder, stomach, and oro-cecal motility. SB, made with moderate sourdough acidification, stimulated more appetite and induced lower satiety. t-SB, having the most intense acidic taste, induced the highest fullness perception in the shortest time. Gallbladder response did not differ among breads, while gastric emptying was faster with sourdough breads. Oro-cecal transit was prolonged for BYB and faster for sourdough breads, especially when made with traditional and long-time fermentation (t-SB), whose transit lasted ca. 20 min less than BYB. Differences in carbohydrate digestibility and absorption determined different post-prandial glycaemia responses. Sourdough breads had the lowest values. After ingesting sourdough breads, which had a concentration of total free amino acids markedly higher than that of BYB, the levels in blood plasma were maintained at constantly high levels for extended time
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