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Design and implementation of a computational environment for high performance scientific computing
Get PDFThis thesis has a three-fold aim. The first one regards the design and implementation of a multiphysics framework for high-performance scientific and engineering computing. The other two aims are built on top of the first one, and they regard the development and implementation of two software components for the simulation of Fluid Flow and Radiative Heat Transfer respectively. The thesis is organized in three parts, one for each aim. The first aim is devoted to the development and implementation of a software platform on top of which it is possible to develop software application aimed to any specific kind of simulation.
The keylines of this platform are: effectiveness, efficiency, flexibility and usability. Following these keylines simultaneously is a challenging task, it can be accomplished only by developing novel strategies for making the following three aspects sinergically work together: numerical methods, physical modeling, computer science. In the first part of the thesis we shall discuss our efforts in this direction. The second aim is devoted to the development and implementation of a Fluid Flow solver able
to deal with Euler and Laminar Navier-Stokes equations. It is able to perform 3D parallel computation on mixed unstructured meshes. Therefore an application on top of the multiphysics framework has been developed and implemented which is able to address the problem of simulating flow fields using the finite volume method. The third aim is devoted to another application, that is, the computation of Radiative Heat Transfer. This aim was accomplished by developing some novel metodologies, such as the development and parallel implementation of a particular Monte Carlo approach for computing radiative heat transfer, and a novel particle tracking algorithm for tracking particle-like entities accross mixed 2D or 3D unstructured meshes in parallel computation
Architettura e movimento: percezione dinamica e progetto dello spazio contemporaneo
Get PDFCan architecture, in respect to dynamics of contemporary urban spaces, create an environment (urban scenarios) where movement, time and distance can coexist with human scale? The answer may probably be affirmative, if it’s possible to find the way the city can, through the architectural language of public spaces, transmit to people the idea of movement and define a parameter of relationship between human scale and dynamics materializing in
them. We deduce the great significance of establishing the perception parameters of movement, because just through movement people find his relationship with contemporary spaces. Everyday people move through different paths crossing the city and realizes a real “journey through urban spaces”.
Chapter 1. Analysis of movement dynamics in cities, order of magnitude, dimensions, functional motivations of transformations in urban form. Analysis is proposed trough the reconstruction of the historic paths of urban spatial transformations and of the dynamics which caused the changes. Historic path and contemporary situation are seen related to city
and people, men and spatial scalar dimension, function and habits, society and identity of
places. This comparison highlights the character of contemporary spaces related to people living in them and crossing them, reconstructs which elements have been lost and which have been gained, during the temporal path of transformation.
Chapter 2. Study of movement languages in the urban image for building a structure of language and a common key to both observers’ perception and urban spaces, joining compositional elements of spatial construction with technics from film editing.
Chapter 3. Vision of contemporary cities as cities of movement. Relationship between cities and people crossing urban spaces. Analysis of perception modes and characters of communication between urban spaces and people: visual signs as image, light, form, fullness,
emptiness. Speed, rhythm and dimension of perception.
Analysis of dynamic function of transit spaces. Some places have the function to drive users in their movement through a path or in their circulation around a node; this character may be defined as dynamic function: places related to dynamic function may be defined as transit spaces. Project of “kinetic language” and “kinetic spaces”. Kinetic language, necessary for coordinating different levels of information, produces a type of space that is suitable for movement and freedom of action, the called “kinetic space”. The project of kinetic space has
to use a kinetic language, appropriate to arouse the perception of movement. At the same time, it has to build the multi dimensionality of spaces, making them adaptable to the different rythms of contemporary urbanity
A generalized finite difference approach to the computation of modes
Get PDFThis thesis deals with numerical techniques for the computation of modes in electromagnetic structures with arbitrary geometry. The approach proposed in
this work is based on the Finite Difference (FD) and Vector Finite Difference (VFD), which are applied to rectangular, circular, elliptical geometries, and to combination of them. The FD is applied using a 2D cartesian, polar and elliptical grid in the waveguide section. A suitable Taylor expansion of the mode function allows, either for scalar and for vector FD, to take exactly into account the
boundary condition. To prevent the raising of spurious modes, the VFD approximation results in a constrained eigenvalue problem, that has been solved using a decomposition method. All approaches presented have been validated comparing the results to the analytical modes of rectangular and circular waveguide, and to known data for
the elliptic case. The standard calculation of the waveguide modes using FD requires the use of two different grids, namely one for TE modes and the other for TM modes, due to the different boundary condition. It has been shown that a single grid can be used for all modes, thus allowing an effective mode-matching solution. The FD approach has been extended to waveguides (and apertures) with irregular boundaries, and therefore non-regular discretization grids. It has been shown that a suitable FD approximation of the Laplace operator is still possible. A ridged-waveguide, with trapezoidal ridges, and a rounded-ended waveguide
have been considered in detail
Opposite role of CD4+CD25+ regulatory T cells and T helper 1 lymphocytes in collateral vessels development
Get PDFBackground: Development of collateral blood vessels is an important compensatory mechanism in response to impaired blood flow due to artery occlusion/stenosis. Several inflammatory cell subpopulations including T lymphocytes are involved in such process. Stabile and colleagues showed that CD4+ and CD8+ T cell subsets are both necessary for efficient arteriogenesis. However the contribution of different CD4+ T cell subsets such as T helper (Th) or the immunosuppressive regulatory CD4+CD25+ T cells (Treg)
in collateral responses is largely unknown.
Aim of the study: The present study aims at characterizing the role of Th1, Th2 and Treg in the growth of collateral vasculature following artery occlusion.
Methods: A mouse model of peripheral ischemia by surgical femoral artery occlusion (hindlimb ischemia model) in CD4 knockout mice (CD4-/-) lacking CD4 T cells was used. These mice displaying impaired collateral responses, were used as
recipients in rescue experiments in which was studied the effect of i.v. injection (reconstitution) of different CD4+ T cell subsets purified from wild-type animals. Blood perfusion and limb function impairment were measured over
time by laser Doppler imaging and by a semiquantitaive ambulatory impairment clinical score, respectively.
Results: Reconstitution with CD4+ naïve (composed of effector cells) but not memory T cells (comprising both effector and Treg) restored the capacity to recover
blood flow and limb function of CD4-/- mice. In addition CD4+ memory T cells depleted of the Treg cell subset were effective in restoring collateral response in recipient animals. Furthermore in vitro polarized Th1 but not Th2 cells supported the recovery of blood perfusion and limb function following femoral artery occlusion.
Conclusions: Altogether these data indicate that Th1 but not Th2 cells act as positive regulators of collateral vessels development while Treg cells inhibit such
response. The identification of specific circulating cellular subsets playing either as positive or negative regulators of collaterals growth may be exploited for the identification of novel easily detectable molecular markers
for the assessment of the individual capacity to compensate vascular occlusion and for the design of novel therapeutic approaches for peripheral and cardiac ischemic disease
Estrazione di composti biologicamente attivi da piante della Sardegna
Get PDFThis research work has been focused on the supercritical fluid extraction and characterization of volatile oils having interesting biological activities, possibly susceptible of therapeutic applications. A further aim of this work was to separate biologically active molecules and nutraceuticals by means of SFE at high pressure. The investigated species have been selected on the basis of
ethnobotanic information regarding, in particular, species endemic of Sardinia or that can be easily cultivated there and containing compounds of pharmacological interest.
Extraction by means of supercritical CO2 has been preferred to the traditional techniques because of a number of advantages. First of all the obtaining of pure extracts deprived of organic solvents and of degradation compounds and not being modified by the loss of water-soluble compounds. The chemical characterization of extracts has been realized by means of different chromatographic
techniques such as GC-MS, GC-FID and HPLC. Concerning the main results, the supercritical extraction at 250 bar on Salvia desoleana aerial parts allowed us to obtain an extract containing a relevant amount of sclareole: 811 μg/mg, determined by the internal standard method. These samples, tested on human cells model, showed a good
antioxidant and cytoprotective activity. As far as the wheath germ oil is concerned, the SFE carried out at 250 bar supplied extracts of good quality. The HPLC and GC-FID analyses of these extracts highlighted a PUFA and Vitamin E
content greater than the those obtained by traditional solvent extractions. The SFE Pistacia lentiscus essential oil, tested in vivo on an oxidative model of the mice frontal cortex induced by hyschemia/riperfusion, BCCAO, showed a relevant protection against lipidic peroxidation. The Myrtus communis essential oil, tested in vivo on mice, demonstrated a good antinflammatory action against the ear edema induced by croton oil and against the cotton pellet-induced granuloma. Among the investigated Sardinian verbenacee and lamiacee such as Vitex agnus-castus, Satureja
thymbra and Thymus capitatus, containing an essential oil particularly rich in phenolic compounds, showed a good antimicrobial activity and could be employed in therapeutic applications. A comparative analysis on the composition of essential oils obtained from Sardinian and Portuguese
plants (Bupleurum fruticosum, Smyrnium olusatrum, Calamintha nepeta nepeta and Achillea millefolium) showed the existence of different chemotypes and showed that derivatives of Sardinian origin have a greater antimicrobial activity. Among the studied vegetable species coming from regions outside Sardinia, it is noteworthy the comparison among the Laurus nobilis leaves oil from
Tunisia and Algeria that showed a strong variability of composition related to their geographical origin. Tunisian oils showed a greater biological activity than the Algerian ones. It has been also demonstrated that berries essential oil of Juniperus oxycedrus ssp. macrocarpa, J. oxycedrus ssp. rufescens and J. phoenicea possess a relevant antioxidant activity
Architetture per il governo dell'acqua. L'infrastruttura riletta: il sistema idrico del Taloro
Get PDFThis work can be read as the result of the analysis of the "dam system", ie a system in which are a lot of the factors.
What is being proposed is an attempt to read in behind disciplinary lenses of the Architecture, regulates of the organization of space. In this challenge the basis of such an approach is immediately intriguing: risemantizzare the vast infrastructure designed on the principle of action and reaction, which is located where the rocks are stronger, where the water flow is more favorable to the altitude appropriate to the gravity pushes the liquid mass quickly enough to change their energy into mechanical energy and then electricity, with storage capacity sufficient to enable a more secure and continuous use by humans for agricultural purposes, and civilians. The dam, and everything that revolves around, is thus the means, never the end. This consideration seems to only seems to move away from more detailed considerations regarding the subject matter for its own sake: the wall of stone or concrete. If this is the Science of Design Architecture and Building, then the great walls that block the course of the waters are also Architecture; with necessary clarifications and distinctions. At first approaches the dam looks like a natural element, uncritical, formal, typological and especially functional and sincere. The dam is spontaneous: places where it is called to respond better to the stresses to which it must answer and, depending on the location, assumes the form best suited as a shrub is best suited to sites that host forming and structuring according to the deeds that nature imposes on him, the dam is uncritical: apparent as a result of interaction is objective structure of shapes and designs derived from knowledge, opinions, beliefs, and physical principles totally shared, the dam is formal and typological: its infinite variations, because infinite are the parameters that from time to time come into play and govern the form, does not exclude his membership precise typological categories. But above the dam is functional: its role is to counter a reaction to water point by point, the overall shape is thus the result of this interaction. Sure, many are the ways in which the designer intended the combination action and reaction, and governandone indirizzandone geometry patterns to executive rather than others, if the reaction has to balance the water pressure (operation) mode is the direct consequence of as a (form)."All these buildings must have requirements for robustness, utility and beauty. Will sound when the foundations were built with materials chosen with care and without avarice, rest deeply and firmly on the ground below; utility, when the distribution of the internal space of each building shall be appropriate and practical to use, beautiful, finally, when the appearance of the work will be enjoyable for the harmonious proportion of the parts that you get with the shrewd calculation of symmetries. (Vitruvius, De Architecture, the third book. "If you disregard for a moment one of the vertices of the Vitruvian triad (venustas) as proposed by Claude Perrault giving it to naturally acquired, it is hard not to read a complete consonance about the case study under consideration . Total gross similarity to one aspect: a concrete wall can be applied the rules of subjective beauty and harmonic proportion of the parts
Strategie di riduzione del rischio residuo nella difesa delle colture vitivinicole e del pomodoro
Get PDFBackground: Pesticides are used to control pests and diseases in modern agriculture but unfortunately their residues can be found on agricultural crops, and in the human’s dietary. Although the best way to decrease the risk associated with the presence of pesticides on agro-food
is following organic farming techniques, most farmers may not avoid the use of chemicals in pest management strategies. A good approach to the problem should therefore guarantee good agricultural yields and low pesticide residues allowing the use of environmental safety pesticides on crops, so joining consumer’s safeness with farmer’s necessity. Results: The behaviour of various pesticides used in IPM strategies on grapes and tomatoes were studied. All the analytical methods showed good recoveries, and good separation of the molecules.
Repeatability and intermediate precision showed good results, and LODs and LOQs were far below the MRLs set by EU for these pesticides in tomatoes and grapes. The analysis of pesticide residues on tomatoes showed that cv. with little berries accounted for higher residue levels than cv. with big berries. They also showed an high persistence of azoxystrobin, cyproconazole, cyprodinil,
penconazole, tolclofos-methyl, mepanipyrim, pyrimethanil, famoxadone fenamidone, fenhexamid, iprodione, and a rapid degradation of triadimenol, cymoxanil, iprovalicarb, fenarimol, and fludioxonil. On grapes, the behaviour in field and the transfer to wine during winemaking of
iprovalicarb, indoxacarb, and boscalid, was studied. The residue levels found in grapes were far below the MRLs set for grapes in EU, accounting at harvest time 0.81, 0.43, and 4.23 mg/kg for iprovalicarb, indoxacarb, and boscalid, respectively. The residue levels in the samples treated with
boscalid may have residual problems (due to an accumulation effect) if repeated field treatments will be performed. Winemaking experiments showed a complete transfer of all pesticide from grapes to the must, while in wine the residues were low or negligible due to the adsorbing effect of lees and pomace. The clarification experiments showed a good removal of pesticide residues from the wine media, for all pesticides. The data obtained in two years survey of pesticide residues on wines following IPM strategies, showed residues less than maximum residue limits (MRLs). The
most pesticides present a residue absent, some (benalaxyl, metalaxyl, iprovalicarb, penconazole, cymoxanil and thiophanate-metyl) showed a residual below the minimum limit of detection (LOD). No residues were found above the LOQ (0,01 mg/kg). Conclusions: The obtained data showed the possibility to get tomatoes and wine at "zero residue"
or, at least, with residues below the limit of quantification (LOQ). The data collected on tomato
have also shown the difference in initial deposition of pesticide joined to the size of the berries in order to obtain products with lower pesticide residues, paying more attention to chemical treatments for the defense of cultivars with small berries
Sistemi di presa e movimentazione di robot non convenzionali
Get PDFThis thesis focuses on the design of some main components of a lunar rover assigned to working tasks. The main task of this rover is to clear areas of the lunar soil allocated to the building of a lunar base. In the first part of the work the lunar environment is studied and described with
particular attention to the rover tasks. The rover in the final configuration will be able to advance in all directions on the soil, to control the attitude and to grasp and to remove obstacle and object on the soil. It will be provided by a frame, legs and will, grasping system.
The design of the lifting system for the attitude control, based on the action of four motorized legs, has been approached with particular regard to the structural characteristics and to the transmission and motorization. The transmission of the lifting system uses a precision coupling between a lead screw and nut, driven by electrical motors. To allow optimal working conditions for the lead screw and nut, the lifting device was designed as a compact apparatus which also comprises a particular joint which is capable to uncouple shear and bending loads transmitted to it from the other parts. The design of the components has to keep into account the peculiar characteristics of the lunar environment. This aspect was considered by an appropriate geometrical design of the components
and a careful choice of the materials. The gripper mechanism of the rover is designed to operate without dedicated motors and it is able to be self-adaptive to the shape of the picked up item also if the object is placed in a non defined position, in any case in a working space. The design optimization of the grasping mechanism, choosing shape and dimension of the different arms, was performed by means of parametric modeling and numerical simulations.
Finally an innovative type of wheel was designed and realized to verify the real ability to operate. The wheel is a non pneumatic system with and integrated suspension and energy scavenging system to power the sensors and control system on board
Perceptual Shape Analysis: approaching geometric problems with elements of perception psychology
Get PDFWhile the recent increase in computational power gave computers an irreplaceable spot in our lives, humans still have to rely on their innate capabilities for some tasks that no electronic device can outperform. Those processes strictly linked to survival tasks, like hearing, vision or social interaction are the fields where the human being shows an efficiency that no machine can compare to.
Limiting the discussion to the field of shape analysis and recognition, this work takes inspiration from the most influential studies on human perception to demonstrate how our brains perform simple operations that allow us to unambiguously recognize a viewed object, while the current state-of-the-heart algorithms heavily rely on mathematical computations based on data, given by the shape primitives, that are of no use to a human observer.
By mimicking human behaviour into the proposed algorithms, the author introduces the paradigm of Perceptual Shape Analysis, obtaining fast and efficient solutions for the main Shape Analysis problems while maintaining a complete independence on the object representation. This new approach is, in the author's opinion, an innovative and fresh point of view that could bring inspiration for the future evolution of the field
Caratterizzazione dimensionale e morfologica di nanoparticelle lipidiche contenenti molecole farmacologicamente attive
Get PDFWith the advent of nanotechnology, great interest is being dedicated to the interactions of nanomaterials/nanoparticles with human beings. All the interactions occurring due to an intentional exposure are investigated by a new research field named Nanomedicine. As this name may suggest, the use of drug delivery systems, sized in the nanometric scale, may favor overcoming anatomical barriers to reach, passively or by a targeting design, the body area to be pharmacologically treated.
In this thesis, we focused our attention to the morphological and dimensional characterization of
pharmaceutical lipidic nanoparticles (NP). These carriers were selected because we hypothesized that they could be good candidates for potent but lipophilic drugs that cannot be systemically administered with conventional formulations (e.g., solutions, dispersions). In addition, we focused on
their preparation and characterization to evaluate potential therapeutic applications based on shape
and size. Specifically, we prepared two types of NP named nanocapsules (NC) and nanoemulsions (NE); the former differs from the latter for a polysaccharidic capsule. Several drugs (ibuprofen and its sodium salt, transretinoic acid, paclitaxel, AZL 6 and 38) and two fluorescently-labeled lipids (i.e.,FITC-PE, NBD) have been entrapped within both NP. We found that lipophilic molecules were
completely encapsulated in both NP. In contrast, in the case of the hydrophilic drug, the polysaccharidic capsule causes ibuprofen sodium salt to be entrapped with a greater efficiency in NC than NE (i.e. 92.6 % IE in NC vs. 20.4 % IE in NE). Morphological analysis has been carried out on NP, that were not subjected to a purification
treatment, by TEM, and in a few cases also by Cryo-TEM. Although the sample drying step showed to be very critical in producing artifacts, we arrived to the conclusion that particles were spherical. Dimensional analysis has been carried out with TEM and DLS on NP subjected or not-subjected to two different purification methods (i.e., centrifugal filtration, dialysis). The rational of purifica-
tion is to remove molecules that, potentially, were not assembled in the NP. The DLS analyses allowed to measure dimensions (Z-Ave) at both 25° and 37°C, and to obtain the polydispersity index(PDI) and superficial charge (ZP). Results showed that NC are positively charged (ca. 45.7 mV)
and sized averagely 185-230 nm at 25°C. Their PDI range is 0.145-0.198. In contrast, NE are negatively charged (ca. -58.5 mV) and sized averagely 142-153 nm at 25°C. Their PDI range is 0.111-0.135. By increasing temperature to 37°C, NC and NE dimensions are affected up to a - 10% and + 3 %, respectively. Ranges of PDI change a little, and become 0.131-0.178 and 0.120-0.133 respectively for NC and NE. It seems that temperature might give energy for a better ar-
rangement of molecules and drugs. Hence, also ZP changes: in NC it was possible to observe, in almost all cases, a decrease up to 23%. In NE, we observed a correlation between PDI and ZP: e.g.,if PDI increases ZP decreases; in any case, values are not larger than +-17%. Purification by centrifugation differently affects NP. In the case of NC dimensions increase (22-53%) as well as PDI (15-108% = 0.210-0.342), whereas ZP might increase or decrease depend-
ing on the entrapped drug (+- 12%). In the case of NE, dimensions stay stable (≤ 1%) but their PDI might change significantly (-2 - +64% = 0.110-0.221), and ZP decreases (0.4-20%). Dialysis is not indifferent either, and results also vary with dialysis time. After 48 h we observed the followings. In the case of NC, dimensions increase (17-52%), PDI decreases (5-46%) and ZP may increase or
decrease (-8 - +17%). In the case of NE, dimensions slightly decrease (3-5%), PDI decreases (3-27%), and ZP increases (19-32%). In conclusion, these NP are suitable candidates for further developments on pharmaceutical ap-
plications, however their characterization should be accurately set-up to mimic body fluids and conditions at the area to be pharmacologically treated