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Il rilevamento dei depositi quaternari della bassa valle del F. Alento insieme alla analisi di preesistenti stratigrafie di sondaggio ed un dettagliato rilevamento geomorfologico dell’area , hanno consentito di ricostruire alcune delle principali tappe morfoevolutive che hanno caratterizzato l’aggradazione e la pro gradazione della Piana dell’Alento durante il Pleistocene superiore e soprattutto durante l’Olocene. Il quadro della cronologia relativa degli eventi, sviluppato in base a criteri stratigrafici e geomorfologici, è stato integrato da alcuni dati di cronologia assoluta ottenuti sia mediante datazioni C14, sia facendo uso di evidenze archeologiche e di fonti storiche varie. Sono state inoltre effettuate analisi sulla microfauna fossile ad ostracodi e foraminiferi di alcune formazioni onde definire l’ambiente di deposizione. L’analisi stratigrafica del sottosuolo della bassa valle dell’Alento ha evidenziato la presenza di una successione di riempimento vallivo, potente fino a oltre 50 m e costituita da depositi epiclastici di ambiente litorale, transazionale e fluviale. Essa rappresenta il frutto di almeno due distinte fasi di aggradazione della valle, separate da una fase di re incisione ascrivibile alla regressione würmiana. La parte terminale del fondovalle ha caratteri di piana costiera e risulta impostata in prevalenza su depositi litorali, eolici e transazionali riferibili alla trasgressione versi liana. La più interna linea di costa di questa trasgressione disegna una sorta di ria, poco incastrata entro la pianura pleistocenica, che si spinge fino a 2,5 km più all’interno della costa attuale. Via via più rettilinee e più avanzate risultano le linee di riva relative alle fasi tardo-oloceniche di pro gradazione. L’utilizzo integrato di evidenze stratigrafiche (di superficie e di sottosuolo), geomorfologiche ed archeologico-storiografiche, ha permesso di riconoscere almeno sei paleo tracciati costieri di età compresa tra l’attuale ed il VI secolo a.C. I più antichi tra questi permettono anche di definire meglio la paleogeografia dell’area all’epoca della celebre colonia magno-greca di Elea, posta su di un promontorio al margine orientale della piana. Il periodo di massima ampiezza della piana costiera è collocabile intorno al tardo Medioevo, quando la linea di costa risultava notevolmente più avanzata di oggi.

This paper reports information about the presence of three allochthonous reptiles species in Calabria: Testudo marginata, Trachemys scripta elegans and Chamaeleo chamaeleon. The first one was found in three sites located in the Catena Costiera Massif and in the Crati Valley (Northern Calabria). The slider turtle was found in seven different sites throughout all the region. It massively colonised the Angitola artificial lake: here, this turtle lives in natural conditions and its reproduction was confirmed by the presence of nests, eggs and hatchlings. C. chamaeleon is present in sandy coastal habitats near Palmi and Gioia Tauro (Southern Calabria). From a conservationistic point of view, serious damages to autochtonous species could be caused by the spreading of T. scripta elegans: this species has already determined the local extinction of Angitola’s Emys orbicularis populations., Acta Herpetologica, Vol 5 No 2 (2010)

This work presents a semi-empirical correlation for the swirl number of a radial-type swirl generator under different conditions of both the Reynolds number and the angle of the swirler channels used to generate the flow tangential velocities. Quantitative velocity measurements are carried out via stereoscopic particle image velocimetry (PIV) to characterize the three-component velocity field of the swirling jets in the proximity of the nozzle exit for four values of the Reynolds number (i.e., 12,800, 20,800, 31,100 and 41,500) and nine swirl angles ranging from 0° to 20°. Such data is used to estimate the values of the swirl number from different theoretical formulations. Semi-empirical formulas are derived based on the mass and angular momentum conservation laws and analytical approximations of the quantities involved in the definition of the swirl number. These formulas elucidate the dependence of the swirl number on the geometrical parameters of the radial-type swirl generator, in particular on the swirl angle, and include coefficients estimated empirically from the velocimetry data, which essentially depend on the exit velocity distribution. The derived correlations may be useful for design and analysis purposes.

The effectiveness of synthetic jet actuation on the wingtip vortices produced by an unswept, low aspect ratio, rectangular wing at a chord Reynolds number of 8.16 × 10 4 is experimentally investigated. The synthetic jet is operated at different actuation frequencies and amplitudes in order to investigate five different control cases characterized by different momentum coefficients and dimensionless frequencies, for a comprehensive parametric study. In particular, the instability frequencies (known as Crow and Widnall) characterizing the wingtip vortex dissipation, are chosen among the tested synthetic jet actuation frequencies. A phase-locked stereoscopic particle image velocimetry is employed to analyze the development of the wingtip vortices in the near wake at a distance from the wing trailing edge of 3 chord lengths. The time-averaged results suggest that the synthetic jet actuation greatly affects the wingtip vorticity distribution causing an outward diffusion which increases with the actuation frequency, with a maximum reduction of 46% on the peak value. On the other hand, when the synthetic jet is operated at the Crow instability frequency, the wingtip induced velocity shows its maximum decrease equal to 29% with respect to the baseline case. The phase-averaged analysis reveals a clear relation between the synthetic jet blowing and suction phases and the periodic variation of the vortices features. In correspondence to the blowing phase, the wingtip vortices undergo a huge diffusion and they are characterized by a larger diameter, higher circulation, and lower induced velocity. These findings confirm that this synthetic jet control configuration can represent a useful device to promote the vortex dissipation and reduce the wake vortex hazard.

This paper reports on a parametric study of the impingement heat transfer from swirling jets issuing from a circular nozzle. The swirl velocity component is imparted to the flow via a tangential entry into a recirculation chamber located upstream of the nozzle; the degree of swirl is varied by changing the angle of the channels leading to the chamber with respect to the radial direction. The effects of the dimensionless impingement distance (H/D = 1, 2, 3, 4, 6, 8, 10, 12, 14 with D being the nozzle diameter), the swirl number (S = 0, 0 . 078, 0 . 22, 0 . 37, 0 . 54) and the Reynolds number (Re = 20,800 , 31,100 , 41,500) on the spatial distribution of the heat transfer are investigated by means of infrared thermography and the heated thin foil sensor. The present results show that the swirl number and the impingement distance significantly influence the structure of the heat transfer distribution, while the Reynolds number affects essentially the magnitude. Four distinct ranges with different behaviours can be identified by distinguishing between weakly or non swirling jets (0 ≤S ≤0 . 22) and moderately swirling jets (0 . 37 ≤S ≤0 . 54) and between short and long impingement distances (1 ≤H/D ≤4 and 6 ≤H/D ≤14 respectively). A comparative assessment of the performance of the swirling jets is carried out by focusing on the area-averaged Nusselt number distributions. It is found that in the range of short impingement distances and over relatively small target areas an enhancement of the heat transfer rates can be obtained at a small extent by adding a weak swirl with no detrimental effect on the uniformity of the distribution and at a larger extent by a moderate swirl with a deterioration of the uniformity. For long impingement distances no enhancement is observed, although swirl yields a significant reduction of the non-uniformity. Finally, correlation laws of the area-averaged Nusselt number as a function of the control parameters are derived in the four regimes identified.

Sweeping jets are oscillating jets generated by fluidic oscillators, i.e., devices designed to produce an oscillation of the flow without the use of any moving parts (Raghu, 2013). A typical configuration of such devices consists of an expansion chamber connected to a high-pressure supply via a converging nozzle and provided with feedback channels. The oscillating motion in the expansion chamber is triggered by an inherent flow instability and sustained by the flow rate across the feedback channels. Recently, sweeping jets have been studied in flow control applications for noise reduction, separation and circulation control over airfoils, control of resonant cavity oscillations and deflection of jets. The advantageous features of fluidic actuators, among which are the wide range of operating frequencies (up to kHz with meso-scale) and the distributed momentum addition, have also stimulated an increasing interest in their application to electronics cooling. Several recent studies on the convective heat transfer from impinging sweeping jets (e.g., Hossain et al., 2018; Park et al., 2018) have shown that, compared to conventional round jets, they offer higher cooling rates with better uniformity at least for small jet-to-plate spacings.

This paper investigates the calibration and measurement uncertainty related to the use of different camera models in optical systems that include refractive surfaces. A refractive surface is an interface between media with different optical properties which introduces distortions in the imaging process due to the refraction of the lines-of-sight. This is an issue common to all the investigations of fluids flowing around or inside transparent solid geometries and is of relevance for a strong curvature of the solid/fluid interface. Appropriate modelling of the refractive effects is possible by integrating the pinhole camera model with a ray-tracing method, as demonstrated in a previous work (Paolillo and Astarita 2020 IEEE Trans. Pattern Anal. Mach. Intell.). On the other side, analytical camera models with a pure mathematical foundation, like those based on polynomials or rational functions, are classically used in the PIV/PTV community. Due to the non-linear nature of the involved distortions, the accuracy of these models in representing the imaging process in presence of refractive geometries depends strongly on the polynomial order and noise of the data used for the calibration. The current work provides a numerical estimate of the uncertainty inherent to the analytical camera models by using data generated via a reference refractive camera model. The present results show that high accuracy requires high orders, which implies a large number of calibration parameters and high demand for computational resources. In particular, the rational mapping functions exhibit superior performance compared to the polynomials, although their calibration is found to be sensitive to image noise and they might yield large extrapolation errors. An experimental verification is also reported, which shows that for the estimation of the velocity statistics a 7th order polynomial model offers results comparable to those of a refractive camera model.

The present paper reports on a time-resolved three-dimensional experimental study of turbulent Rayleigh-Bénard convection inside a cylinder with one-half aspect ratio. The working fluid is water and the Rayleigh and Prandtl numbers are, respectively, and. Measurements are carried out via time-resolved particle tracking velocimetry for a relatively long time (approximately four hours) and due to the limited size of the convection cell (internal diameter of mm) the whole interior of the cylindrical sample is investigated. This allows a proper analysis of the statistical behaviour of the flow across the time. Proper orthogonal decomposition (POD) is used to extract the characteristic modes of the turbulent thermal convection. It is shown that the low-order POD modes are strictly related to the formation of a large scale circulation (LSC) and its organization in a single-roll state (SRS) or a double-roll state. Innovative criteria for the identification of the instantaneous flow state based on the POD analysis are also proposed. Such criteria are proved to overcome the limitations of methods commonly adopted in the previous literature and relying on the analysis of the azimuthal profiles of the temperature or the vertical velocity at three different heights (one quarter, one half and three quarters of the cell height). Compared with the latter methods, the POD-based criteria identify a larger frequency of occurrence of the SRS, which is recognized as the most frequent state of the LSC in the investigated conditions.

This work presents a comparison of the results from an experimental and numerical investigation of impinging swirling jets operating at Reynolds number and swirl number equal to 30’000 and 0.61, respectively. Measurements are carried out via InfraRed Thermography using a heated thin foil as heat flux sensor, varying the impingement distance from 1 to 10 nozzle diameters. Numerical simulations of the same configurations are performed with a commercial software (Ansys Fluent) to test the capability of different Reynolds-Averaged Navier-Stokes (RANS) equations-based turbulence models in predicting the heat transfer rates from wall to the swirling impinging jets.

Investment casting is a leading technique to manufacture very reliable components. The design and the optimization of this process are usually performed by simulation software and/or by means of simplified models based on heat transfer coefficients obtained by solving the inverse heat conduction problem (IHCP). Both methods require experimental tests, that involve temperature measurements, aiming at validating the investment casting simulations or evaluating the heat transfer coefficients in the IHCP. Typically, all these temperature measurements are performed with thermocouples that are characterized by several limits, such as heat transfer alteration, approximate location of the measurement points, and spatial-limited evaluation of the heat transfer coefficients. In order to overcome these limits, the infrared thermography is proposed as an alternative measurement technique. The infrared thermography allows to obtain complete and spatial-accurate information about the surface temperature of an investigated body which, in particular, is a ceramic shell mould in the present work. Since the infrared thermography is a 2D technique, the purpose of this work is to provide a procedure to experimentally reconstruct the 3D temperature surface distribution of this ceramic shell mould in a real industrial environment with all its space and time constraints.

The present paper aims at establishing the synthetic jet technology capabilities in controlling the von Kármán street behind a circular cylinder. The circular cylinder, placed in an open-circuit wind tunnel, presents a slot in its rear position, through which the synthetic jet is issued. The Reynolds number, based on the circular cylinder diameter and the free-stream velocity, is equal to 4600 and the von Kármán street is characterized, in the baseline configuration (i.e. without synthetic jet), by a shedding frequency of 16.2 Hz. Several synthetic jet operating conditions are tested. Therefore, the effects of the momentum coefficient (%, 10.8% and 21.6%) and the dimensionless frequency (, 0.98 and 1.96) on the von Kármán street behaviour can be analysed. Instantaneous two-dimensional in-plane velocity fields are measured in a plane containing the synthetic jet slot axis using multigrid/multipass cross-correlation digital particle image velocimetry. These measurements have been used to investigate the mean flow quantities and turbulent statistics of the phenomenon. In addition, the wake extent and behaviour (i.e. symmetric or asymmetric) are analysed as well as the drag coefficient, for each configuration. The extent of the wake region decreases as the momentum coefficient and/or the dimensionless frequency increase, while the symmetric/asymmetric wake behaviour is found to be governed by a different control parameter: the synthetic jet Reynolds number based on its impulse. As regards the drag coefficient, a maximum reduction, of approximately 35%, is found for the configuration at and.

Computed tomography of chemiluminescence (CTC) is one kind of volumetric tomography which can recover 3D flame structures and has found extensive applications for spatiotemporally resolved measurements of flames. However, the existing CTC techniques rely on the pinhole model and fail when the flames are confined within a cylindrical glass due to image distortion caused by the refraction on both the internal and external surfaces of the glass. In this work, a refined camera model was developed by combining the pinhole camera model with Snell's laws using a reverse ray-tracing method to incorporate the effects of refraction. A proof-of-concept demonstration of CTC based on the refined camera model was conducted on a swirl flame confined within a 20-mm-thick K9 glass. The results proved the superiority of such technique against the existing version in terms of reconstruction accuracy. This work is expected to be especially useful for the study of combustion phenomena such as combustion instability for which the flames are typically confined within cylindrical combustors.

Synthetic jets are zero-net mass flux flows that have been recently used in a wide range of flow control applications, among which the control of bluff body wakes. An optimal control is based on an appropriate tuning of the involved parameters, which implies knowledge of the effects of such parameters on the flow field. The present work reports on an experimental investigation of the active open-loop control of a cylinder wake at Reynolds number equal to 4600 using a slot synthetic jet located at the rear stagnation point. Three values of f+ (0.49, 0.98 and 1.96) are considered and, for each of them, Cµ is varied among as many different values (5.4%, 10.8% and 21.6%) for a total of five investigated Reynolds numbers ratio R (1.0, 2.0, 4.0, 8.1 and 16.4). The flow field in the cylinder wake is found to be highly sensitive to the variations of f+ and Cµ. By increasing Cµ. and/or f+ the extent of the time-mean recirculation region is observed to decrease. Furthermore, the cylinder wake can exhibit a symmetric or an asymmetric behavior depending on the R. Indeed, at high Reynolds numbers ratio R, the cylinder wake shows a symmetric behavior because of a strong synthetic jet which stops the evolution of the shear layer instability leading to a synchronization of the vortex shedding with the synthetic jet Differently, at low R, the evolution of the cylinder wake shows the classic asymmetric behavior.

In this paper we describe the application of GPR and resistivity (dipole-dipole) methods to an archeological investigation. The aim of this study was to obtain information about buried pre-Roman structures below the Roman residence “Casa dell’Atrio a Mosaico,” in the ancient town of Ercolano (Naples). A number of resistivity (dipole-dipole) and GPR profiles were carried out on the mosaic floor of the house. To perform resistivity profiles in a nondestructive way on the mosaic floor, special flat-base copper electrodes were used. The electrode spacing used was [Formula: see text] and [Formula: see text]. GPR data were collected using [Formula: see text] and [Formula: see text] antennas. The radar profiles were carried out primarily along the electrical profiles in order to obtain a direct comparison between the two methods. Both resistivity and GPR methods evidenced a number of structures buried at shallow depths. Both methods located a structure identified as a conductive body with electric parameters strongly contrasting those of the surrounding material. The archaeological interpretation of such structures is in terms of remnants of walls of pre-Roman houses and of a cistern used for collecting rain, connected to a pipe.

The objective of this investigation was to study and simulate the plough mouldboard soil interaction phenomena. A numerical simulation of the interaction between the soil and the plough mouldboard was performed by utilising the ‘finite volumes’ numerical approach. Simulation was carried out by utilising a three-dimensional free-surface model as well as a soil medium with the constitutive relationship of a non-Newtonian pseudo-plastic material. Such a ‘virtual’ material could properly simulate the global effects of the plough mouldboard – soil interaction of the test soil (sandy loam). Field tests were performed to validate the model using piezo-resistive transducers to detect the normal stresses on 14 points located on the working surface of a plough mouldboard. The stress distribution was then derived by using spatial interpolation and the results compared with the numerical simulation data. The maximum error detected by comparing numerical results with the experimental data set was less than 10%.

In order to evaluate the usefulness of transcranial Doppler (TCD) in carotid artery surgery, 90 patients who underwent carotid endarterectomy were studied. Transcranial Doppler was performed preoperatively with digital compression of the carotid artery and intraoperatively at the time of cross-clamping, together with routine EEG monitoring. The percentage residual middle cerebral artery velocity (%MCAV) during carotid artery compression or cross-clamping was considered. The intraoperative %MCAV at cross-clamping was compared with the values obtained in the preoperative examination during the compression test and with the EEG data; the EEG records were blindly reviewed by a neurologist and divided into three groups: group A, normal; group B, moderate anomalies and group C, major anomalies. There were no significant differences between preoperative %MCAV (compression test) and intraoperative %MCAV (cross-clamping) by separate analysis of the data related to systolic, diastolic and mean velocity. The systolic, diastolic, mean %MCAV and the Gosling index after cross-clamping were then compared with the EEG data: no significant differences were seen between groups A and B; on the other hand, in all patients with major EEG anomalies (group C) the %MCAV at TCD was reduced to 0. In conclusion, preoperative TCD associated with carotid artery compression appears a safe and useful way of identifying patients at risk of cerebral ischaemia during carotid artery cross-clamping. Patients with no residual flow at intraoperative TCD need to be considered as presenting a very high risk of ischaemia and in this group the use of a shunt is mandatory.