A flexible algorithm for detecting challenging moving objects in real-time within IR video sequences

Real-time detecting moving objects in infrared video sequences may be particularly challenging because of the characteristics of the objects, such as their size, contrast, velocity and trajectory. Many proposed algorithms achieve good performances but only in the presence of some specific kinds of objects, or by neglecting the computational time, becoming unsuitable for real-time applications. To obtain more flexibility in different situations, we developed an algorithm capable of successfully dealing with small and large objects, slow and fast objects, even if subjected to unusual movements, and poorly-contrasted objects. The algorithm is also capable to handle the contemporary presence of multiple objects within the scene and to work in real-time even using cheap hardware. The implemented strategy is based on a fast but accurate background estimation and rejection, performed pixel by pixel and updated frame by frame, which is robust to possible background intensity changes and to noise. A control routine prevents the estimation from being biased by the transit of moving objects, while two noise-adaptive thresholding stages, respectively, drive the estimation control and allow extracting moving objects after the background removal, leading to the desired detection map. For each step, attention has been paid to develop computationally light solution to achieve the real-time requirement. The algorithm has been tested on a database of infrared video sequences, obtaining promising results against different kinds of challenging moving objects and outperforming other commonly adopted solutions. Its effectiveness in terms of detection performance, flexibility and computational time make the algorithm particularly suitable for real-time applications such as intrusion monitoring, activity control and detection of approaching objects, which are fundamental task in the emerging research area of Smart City

Experimental and numerical analysis of microstructured surfaces

Heat dissipation is one of the most important issues for the reliability of electronics equipment. Up today, air represents the most safe, cheap, and common working fluid for electronics thermal management applications. Due to its poor heat transfer characteristics, air always flow through enhanced surfaces, such as plain and louvered fins, pin fins, offset strip fins and wire screens, in order to increase the heat transfer area and to create turbulence. Recently, metal foams have been proposed as promising enhanced surfaces to improve the overall heat transfer performance of the cooling system. In several applications air might be not enough for high level of heat dissipation, thus two-phase systems can represent a viable solution. Boiling is the heat transfer mechanism with the highest heat transfer coefficients, thus it can be used to spread high heat fluxes to maintain the wall temperature at low values with compact heat sinks. Microstructured surfaces, such as metal foams and microfin tubes, can exploit positive benefits on the flow boiling mechanism, i.e. they can promote bubble nucleation, reduce onset of nucleate boiling, augment two-phase mixing, enhance critical heat flux. On the other hand, the environmental issues associated to the use of synthetic refrigerants call for a continuous improvement of the technical solutions. Recently, new low-GWP refrigerants, in particular R1234ze(E) and R1234yf, have been proposed as possible alternatives of the traditional R134a. This PhD thesis explores the use of microstructured surfaces for thermal management applications. Metal foams, plain finned and pin finned surfaces are experimentally and numerically investigated during air forced convection. In addition, single- and two-phase flow (vaporization) of refrigerants through a copper foam and in a microfin tube is experimentally studied. The first chapter is focused on the air forced convection through metal foams. Nine copper foams are experimentally tested, and the overall heat transfer coefficients and pressure drops are calculated from the experimental measurements. The effects of the geometrical parameters (foam core height, pore density, and porosity) on the thermal and hydraulic behaviour of such materials are discussed. The experimental data points, coupled with other measurements previously obtained on aluminum foams, have permitted the development of a new semi-empirical equation for the estimation of the foam finned surface efficiency and of the heat transfer coefficient. The air forced convection through plain finned and pin fin surfaces is discussed in the second chapter. Numerical simulations are performed on different geometrical configurations of fin thickness, pitch, and height for the plain finned surfaces, and different configurations of pin diameter, longitudinal and transverse pin pitch, and pin height for the pin fin surfaces. The effects of the geometrical characteristics on the thermal and hydraulic behaviour are reported. From the numerical results, four correlations have been developed for the estimation of the Colburn j-factor and friction factor for plain finned and pin fin surfaces. In the end, an optimization of a plain finned surface is reported. The third chapter proposes a numerical approach to study the air forced convection through metal foams. The real structure of four copper foams, whose experimental results are reported in the first chapter, is obtained by micro-computed tomography scanned images. Once reconstructed, the real foams are meshed and the air flow simulated with a commercial software. Numerical results of pressure drop and heat transfer coefficient are compared against the experimental values. The design and development of a new experimental facility to study the phenomenon of the flow boiling inside microstructured surfaces is reported in the fourth chapter. The numerical design of the test section, which hosts a 200 mm long metal foam, is presented. Every component of the set up is discussed in details. The results of the calibration tests are reported. The flow boiling of refrigerants inside a metal foam is shown in the fifth chapter. The tested copper foam is 200 mm long, 10 mm wide, and 5 mm high. Three different refrigerants are studied: R134a, R1234ze(E), and R1234yf. R1234ze(E) and R1234yf (GWP=6 and 4, respectively) are possible substitutes of R134a (GWP=1400). Tests are run at a saturation temperature of 30 °C, which can be considered suitable for the case of electronic cooling applications, at different working conditions, in order to highlight the effects of the vapour quality, mass velocity, and heat flux on the thermal and hydraulic performance. Finally, the sixth chapter reports some results about the flow boiling of refrigerants inside a 3.4 ID microfin tube. Three different refrigerants are studied: R134a, R1234ze(E), and R1234yf. As for the case of flow boiling inside a metal foam, tests are run at a saturation temperature of 30 °C under different working conditions, i.e. different vapour quality, mass velocity, and heat flux. The experimental results of heat transfer coefficient, vapour quality at the onset of the dryout, and pressure drop are compared against values predicted by correlations from the open literatur

R1233zd(E) and R245fa Flow Boiling Heat Transfer and Pressure Drop inside a 4.2 mm ID Microfin Tube

This paper presents R1233d(E) and R245fa flow boiling heat transfer and pressure drop measurements inside a mini microfin tube having internal diameter at the fin tip equal to 4.2 mm, 40 fins 0.15 mm high, and a helix angle of 18°. The tube was brazed inside a copper plate and electrically heated from the bottom. Sixteen T-type thermocouples were located in the copper plate to monitor the wall temperature. The experimental measurements were carried out at a constant mean saturation temperature of 30 °C, by varying the refrigerant mass velocity between 100 kg m-2 s-1 and 300 kg m-2 s-1, the vapour quality, and the heat flux from 15 to 90 kW m-2. The experimental results are here presented in terms of two-phase heat transfer coefficient, onset dryout vapour quality, and frictional pressure drop. Moreover, R1233zd(E) has been proposed as low GWP alternative to R245fa. In this paper, the two fluids performance is compare under the same working conditions and commented. Finally, the experimental measurements were used to assess a few selected models for boiling heat transfer coefficient and frictional pressure drop estimations available in the open literature for microfin tubes

R134a and its low GWP substitutes R1234yf and R1234ze(E) condensation inside a 4mm horizontal smooth tube

The substitution of HFC134a with low GWP refrigerants is one of the most important challenge for refrigeration and air conditioning. The possible substitutes include natural refrigerants, such as HC600 (Butane) and HC600a (Isobutane), and also synthetic refrigerants, such as HFO1234yf and HFO1234ze(E). The HC refrigerants exhibit very low GWP, 3 and 4 HC600a and HC600 respectively, good thermodynamic and transport properties, and pressure and volumetric performance very similar to HFC134a. The major drawback of HC refrigerants is their high flammability, being classified in class A3 according to ASHRAE classification. Also the HFO refrigerants present a mild flammability, being classified in class A2L. In fact it is very difficult to found low GWP substitutes for traditional HFC refrigerants with no flammability, as a weak chemical stability and / or a big chemical reactivity are presuppositions for low GWP. Both HFO1234yf and HFO1234ze(E) seem to be very promising as substitute for HFC134a, showing a GWP lower than 1 together with pressure and volumetric properties closely near to those of HFC134a. This paper presents the comparative analysis of HFC134a HFO1234yf and HFO1234ze(E)during saturated condensation inside a 4 mm horizontal smooth tube. The experimental tests were carried out at three different saturation temperatures (30, 35, and 40 °C) at decreasing vapour quality up to sub-cooled liquid condition, to evaluate the specific contribution of refrigerant mass flux, mean vapour quality, and saturation temperature. The refrigerant mass flux ranges from 100 to 600 kg m-2 s-1. The experimental measurements were reported in term of condensation heat transfer coefficients and frictional pressure drops and plotted in non-dimensional co-ordinates showing the heat transfer factor and the friction factor against the equivalent Reynolds number. A transition point from gravity dominated and forced convection condensation was found for an equivalent Reynolds number around 10000-20000. HFO1234yf and HFO1234ze(E) exhibit heat transfer coefficients and pressure drops similar to HFC134a and they seem to be valuable long term low GWP substitutes for HFC134a. The experimental heat transfer coefficients in the forced convection condensation regime were very well predicted by the Akers et al. (1959) model, whereas the Friedel (1979) correlation was able to reproduce the frictional pressure drop data both in gravity dominated and forced convection condensation regimes

R1234yf FLOW BOILING HEAT TRANSFER INSIDE A 3.4 mm ID MICROFIN TUBE

The use of synthetic refrigerants with a non-negligible Global Warming Potential or, on the contrary, of natural but flammable or toxic natural fluids calls for the charge minimization of the refrigerating and air conditioning equipment. The refrigerant charge minimization as well as the use of eco-friendly fluids can therefore be considered two of the most important targets for these applications to cope with the new environmental challenges. Traditional microfin tubes are also widely used in air and water heat exchangers for heat pump and refrigerating applications during condensation or evaporation. The possible downsizing of microfin tubes can lead to more efficient and compact heat exchangers and thus to a reduction of the refrigerant charge of the systems. Furthermore, over the last several years, much research and development effort has been focused on potential refrigerants possessing low GWPs. Among the fluorinated propene isomers which have normal boiling point temperature data published in the public domain, several have low GWP and normal boiling temperatures relatively close to R134a; among them, R1234yf has as a normal boiling temperature approximately 3.4°C lower than that of R134a, with a GWP=4. This paper presents the R1234yf flow boiling heat transfer and pressure drop measurements inside a small microfin tube with internal diameter at the fin tip of 3.4 mm. This study is carried out in an experimental facility built at the Dipartimento di Ingegneria Industriale of the University of Padova especially designed to study both single and two phase heat transfer processes. The microfin tube is brazed inside a copper plate and electrically heated from the bottom. Several T-type thermocouples are inserted in the wall to measure the temperature distribution during the phase change process. In particular, the experimental measurements were carried out at constant saturation temperature of 30 °C, by varying the refrigerant mass velocity between 190 kg m-2 s-1 and 940 kg m-2 s-1, the vapour quality from 0.2 to 0.99, at three different heat fluxes: 10, 25, and 50 kW m-2. The experimental results are presented in terms of two-phase heat transfer coefficient, onset dryout vapour quality, and frictional pressure drop as a function of the operative test conditions

Utilizzo di Immagini Acquisite da Drone Aereo per la Ricostruzione Tridimensionale Realistica di un'Area di Interesse in Tempo Reale

Tridimensional reconstruction of areas and objects of interest from images acquired from aerial drones plays a key role in numerous fields, from the less critical, like urban planning and archeological area survey, to the most critical, like natural disaster monitoring, and search & rescue. Many techniques proposed to deal with this issue require expensive instrumentation or use computationally costly algorithm or need some a priori information that are not always available. Thus, they are not suitable for certain applications or in some specific situations. In order to overcome these limitations, we designed a technique that allows automatically creating 3D models in real-time using only a couple of images of the scene one is interested in, acquired with a cheap compact camera mounted on the drone, without the needing for any additional information. The proposed technique outputs dense true-color 3D models, which give the impression to the user to be physically present within the scene. Tested for monitoring the progress of the works in a construction site, the technique has been capable to create realistic and easy-to-interpret 3D models of areas and objects in less than 1 second and with a sufficient accuracy to permit large-scale surveys

CCR4+ skin-tropic phenotype as a feature of central memory CD8+ T cells in healthy subjects and psoriasis patients

The chemokine receptor CCR4 has emerged as a skin-homing molecule important for the migration of T cells from the blood to the dermis. From our previous data on psoriasis patients, CCR4+ memory T cells emerged as a putative recirculating population between skin and blood. Here we focused our attention on the expression of CCR4 and skin-tropic molecules in the different stages of memory T cell differentiation. We analyzed the chemokine receptor profile in CD8+ and CD4+ CD45RA−CCR7+ (TCM) and CD45RA−CCR7− (TEM) cells. Subpopulations were further divided on the basis of CD62L expression, and the distribution among the subsets of the skin-homing molecule CLA (Cutaneous Lymphocyte Antigen) was evaluated. The characterization was performed on peripheral blood mononuclear cells isolated from 21 healthy subjects and 24 psoriasis patients. The results indicate that (i) the skin-homing CCR4 marker is mainly expressed in TCM cells, (ii) CCR4+ TCM cells also express high level of CLA and that (iii) the more differentiated phenotype TEM expresses CXCR3 and CCR5 but lower level of CCR4 and CLA. This indicates that progressive stages of memory T cell differentiation have profoundly different chemokine receptor patterns, with CD8+ TCM displaying a marked skin-tropic phenotype CLA+CCR4+. Differential skin-tropic phenotype between TCM and TEM cells was observed in both healthy subjects and psoriasis patients. However, patients showed an expanded circulating population of CD8+ TCM cells with phenotype CCR4+CXCR3+ that could play a role in the pathophysiology of psoriasis and possibly in disease recurrence

Hormonal Therapy and Chemoprevention.

Hormone replacement therapy (HRT) can increase the quality as well as the length of life, but a prolonged use can also increase the risk of breast cancer. The combination of HRT and a selective estrogen receptor modulator (SERM) such as tamoxifen may retain the benefits while reducing the risks of either agent. A post hoc analysis of the Italian Tamoxifen Prevention Study showed a borderline significant reduction of breast cancer among women who were on HRT continuously and tamoxifen as compared with continuous HRT users who received placebo. Recent studies suggest that the standard dose of tamoxifen may be reduced to one-quarter (i.e., 10 mg every other day) without loss of its beneficial biological effects. Since the endometrial effect of tamoxifen seems to be both dose and time dependent, a dose reduction could substantially reduce the risk of endometrial cancer while retaining its preventive efficacy. On the other hand, the addition of HRT containing progestins could also minimize the risk of endometrial cancer associated with tamoxifen. Moreover, estrogen should reduce the incidence of vasomotor and urogenital symptoms, which are a major reason for tamoxifen withdrawal in prevention studies. Notably, in the National Surgical Adjuvant Breast Project (NSABP) P-1 trial, women ages 50 or younger had no increased incidence of adverse events, including endometrial cancer and venous thromboembolic events. One possible explanation for the lack of toxicity in premenopause is the presence of adequate circulating estrogen levels which prevent tamoxifen to act as an estrogen agonist at these target tissues. Moreover, data from the current Italian tamoxifen prevention trial indicate that the compliance was substantially higher for de novo and current HRT users as compared to women who never received HRT during the study. The combination of HRT and tamoxifen at low doses could thus reduce the risks and side effects while retaining the benefits of either agent

Tuning electrical properties of hierarchically assembled Al-doped ZnO nanoforests by room temperature Pulsed Laser Deposition

Large surface area, 3D structured transparent electrodes with effective light management capability may represent a key component in the development of new generation optoelectronic and energy harvesting devices. We present an approach to obtain forest-like nanoporous/hierarchical Al-doped ZnO conducting layers with tunable transparency and light scattering properties, by means of room temperature Pulsed Laser Deposition in a mixed Ar:O2 atmosphere. The composition of the background atmosphere during deposition can be varied to modify stoichiometry-related defects, and therefore achieve control of electrical and optical properties, while the total background pressure controls the material morphology at the nano- and mesoscale and thus the light scattering properties. This approach allows to tune electrical resistivity over a very wide range (10^-1 - 10^6 Ohm*cm), both in the in-plane and cross-plane directions. Optical transparency and haze can also be tuned by varying the stoichiometry and thickness of the nano-forests

Gluten deprivation: What nutritional changes are found during the first year in newly diagnosed coeliac children?

Aim: A gluten-free diet (GFD) can expose children to excessive calories and fat intake. The study is intended to verify whether and how food intake, laboratory parameters, and growth are modified by a year of GFD. Methods: In 79 CD (coeliac disease) children (mean age 7.9 \ub1 3.8 years, 52 females, 27 males) diagnosed over 24 months, 24-h food diaries, food-frequency patterns, anthropometric and laboratory parameters (mainly blood sugar, insulin, lipid profile, and homocysteine) were prospectively collected before and during the first year of GFD. Nutrient intakes were compared over time and with recommendations. They were also used as regressors to explain the levels and changes of metabolic and growth variables. p-values < 0.05 were considered statistically significant. Results: Average macronutrient intake did not change during the year. Caloric intake remained below 90% (p 64 0.0001) and protein intake above 200% (p 64 0.0001) of recommendations. Lipid intake was stable at 34% of overall energy intake. Unsaturated fats increased (less omega-6 and more omega-3 with a ratio improvement from 13.3 \ub1 5.5 to 8.8 \ub1 3.1) and so did fibers, while folate decreased. The children who experienced a containment in their caloric intake during the year, presented a slower catch-up growth. Some differences were found across gender and age groups. In particular, adolescents consumed less calories, and females more omega-3. Fiber and simple sugar intakes emerged as implicated in lipid profile shift: fibers negatively with triglycerides (TG) (p = 0.033), simple sugars negatively with high-density lipoprotein (HDL) (p = 0.056) and positively with TG (p = 0.004). Waist-to-height ratio was positively associated with homocysteine (p = 0.018) and Homeostasis Model Assessment (p = 0.001), negatively with fibers (p = 0.004). Conclusion: In the short run, GFD is nutritionally very similar to any diet with gluten, with some improvements in unsaturated fats and fiber intake. Along with simple sugars containment, this may offer CD patients the opportunity for a fresh start. Caloric intakes may shift and should be monitored, especially in adolescents