Bluff Body Flow Control Through Piezoelectric Actuators

Delay separation from bluff bodies leads to drag reduction. An active flow control technique based on piezoelectric actuators has been arranged on a 2D cilynder in subsonic flow. Experimental investigation in precritical and postcritical conditions of the flow has been conducted varying the configurations of the actuators. Drag reduction up to 10% without a complete optimization of the flow control parameters have been obtained

Enabling Non-Linear Quantum Operations through Variational Quantum Splines

The postulates of quantum mechanics impose only unitary transformations on quantum states, which is a severe limitation for quantum machine learning algorithms. Quantum Splines (QSplines) have recently been proposed to approximate quantum activation functions to introduce non-linearity in quantum algorithms. However, QSplines make use of the HHL as a subroutine and require a fault-tolerant quantum computer to be correctly implemented. This work proposes the Generalised QSplines (GQSplines), a novel method for approximating non-linear quantum activation functions using hybrid quantum-classical computation. The GQSplines overcome the highly demanding requirements of the original QSplines in terms of quantum hardware and can be implemented using near-term quantum computers. Furthermore, the proposed method relies on a flexible problem representation for non-linear approximation and it is suitable to be embedded in existing quantum neural network architectures. In addition, we provide a practical implementation of GQSplines using Pennylane and show that our model outperforms the original QSplines in terms of quality of fitting

Multi-time delay, multi-point Linear Stochastic Estimation of a cavity shear layer velocity from wall-pressure measurements

Multi-time-delay Linear Stochastic Estimation (MTD-LSE) technique is thoroughly described, focusing on its fundamental properties and potentialities. In the multi-time-delay ap- proach, the estimate of the temporal evolution of the velocity at a given location in the flow field is obtained from multiple past samples of the unconditional sources. The technique is applied to estimate the velocity in a cavity shear layer flow, based on wall-pressure measurements from multiple sensor

Towards the Identification of a Suitable Commercial Diet for Carpione (Salmo carpio, Linnaeus 1758): A Multidisciplinary Study on Fish Performances, Animal Welfare and Quality Traits

SIMPLE SUMMARY: Carpione (Salmo carpio, Linnaeus 1758) is an endangered precious endemism of Lake Garda (Northern Italy), the largest Italian lake. To date, several bottlenecks about its culture remain unsolved, including the identification of a proper growth-out diet. In the present study, four different grossly isolipidic, isoproteic, and isoenergetic diets containing ingredients from different origins were used for S. carpio culture. Specifically, a diet largely based on marine ingredients, and currently used for carpione farming, was used as control. Three other diets were formulated in order to include relevant percentages of vegetable ingredients or processed animal proteins (at two different inclusion levels). After a three-month feeding trial, fish zootechnical performances, welfare, and flesh quality were evaluated through a multidisciplinary approach, including histology, gene expression, chemical analysis, and Fourier transform infrared spectroscopy (FTIR). This study provided the first insights on carpione physiological responses to different commercial dietary formulations. ABSTRACT: Carpione (Salmo carpio, Linnaeus 1758) is an endangered precious endemism of Lake Garda (Northern Italy), the largest Italian lake. To date, several bottlenecks about its culture remain unsolved, including the identification of a proper growth-out diet. The aim of the present study was to test four different grossly isolipidic, isoproteic, and isoenergetic diets in which the main ingredients had a different origin. Specifically, a diet currently used by local farmers for carpione culture, largely based on marine ingredients, was used as control (CTRL), while the other three diets were formulated by partially replacing marine ingredients with plant ones (VEG) or with different percentages of processed animal proteins (PAP1 and PAP2). The feeding trial was run in triplicate, over a three-month period. No significant differences in growth performance among the experimental groups were observed. However, remarkable histological alterations and inflammatory markers upregulation were observed in VEG group, while PAP inclusion played a role in attenuating inflammation and improving nutrient uptake. Fillet analyses highlighted significant differences in marketable traits and flesh fatty acid composition among the experimental groups, including the reduction of polyunsaturated fatty acids related to PAPs inclusion. In conclusion, PAPs used in the present study promoted S. carpio gut health and absorption capacity, while further studies are required to maintain proper quality traits of the final product

Effectiveness of cardiac resynchronization therapy in heart failure patients with valvular heart disease: comparison with patients affected by ischaemic heart disease or dilated cardiomyopathy. The InSync/InSync ICD Italian Registry

AimsTo analyse the effectiveness of cardiac resynchronization therapy (CRT) in patients with valvular heart disease (a subset not specifically investigated in randomized controlled trials) in comparison with ischaemic heart disease or dilated cardiomyopathy patients.Methods and resultsPatients enrolled in a national registry were evaluated during a median follow-up of 16 months after CRT implant. Patients with valvular heart disease treated with CRT (n = 108) in comparison with ischaemic heart disease (n = 737) and dilated cardiomyopathy (n = 635) patients presented: (i) a higher prevalence of chronic atrial fibrillation, with atrioventricular node ablation performed in around half of the cases; (ii) a similar clinical and echocardiographic profile at baseline; (iii) a similar improvement of LVEF and a similar reduction in ventricular volumes at 6-12 months; (iv) a favourable clinical response at 12 months with an improvement of the clinical composite score similar to that occurring in patients with dilated cardiomyopathy and more pronounced than that observed in patients with ischaemic heart disease; (v) a long-term outcome, in term of freedom from death or heart transplantation, similar to patients affected by ischaemic heart disease and basically more severe than that of patients affected by dilated cardiomyopathy.ConclusionIn 'real world' clinical practice, CRT appears to be effective also in patients with valvular heart disease. However, in this group of patients the outcome after CRT does not precisely overlap any of the two other groups of patients, for which much more data are currently available

Bluff Bodies Flow Control using Innovative Piezoelectric Actuators

An active flow control technique based on “smart-tabs” is proposed to delay flow separation on a circular cylinder and on a simplified bi-dimensional automotive geometry body. The actuators are retractable and orientable multilayer piezoelectric tabs which protrude perpendicularly from the model surface. They are mounted along the spanwise direction with constant spacing. The effectiveness of the control was tested in pre-critical and in post-critical regime by evaluating the effects of several control parameters of the tabs like frequency, amplitude, height, angular position and plate incidence with respect to the local flow. Measurements of the mean static pressure distribution around the cylinder were used to estimate the pressure drag and lift coefficient. To take into account friction and the parasite drag of the actuators wake analysis was performed. The maximum drag reduction achieved in the pre-critical regime was of the order of 30%, whereas in the post-critical regime was about 15%, both for the highest forcing available. In pre-critical condition the active forcing plays an important role on drag and pressure fluctuations reduction. Spectral analysis of the signals from instantaneous pressure transducers (electret microphones) indicated an almost complete suppression of the vortex shedding in active forcing conditions. In post-critical regime, instead, most of the effects are due to passive forcing limiting the active contribution to a maximum of 3%. The results related to the automotive geometry confirm the ones obtained on the circular cylinder, with a maximum attained drag reduction of 13.4% with only small contributions due to active forcing. To evaluate the potentialities of the smart-tabs in real applications power absorption measurements are reported together with energy budget considerations. Finally, the identification of the key non-dimensional control parameters, was performed

Streamwise vortices originating from synthetic jet-turbulent boundary layer interaction

The interaction between a flat plate turbulent boundary layer and a synthetic jet issuing from a rectangular slot slanted with respect to the free stream was studied experimentally using Digital Particle Image Velocimetry (DPIV). Instantaneous flow fields were sampled in a cross-plane downstream of the slot. Results concerning the effects of varying the synthetic jet velocity ratio at fixed stroke length L0 and yaw angle, and the effects of varying the orifice yaw angle at a fixed frequency are presented. The formation of a pair of counter-rotating vortical structures, completely embedded in the boundary layer, was observed in the mean flow field when the slot was aligned with the cross-flow. As the slot yaw angle was increased the leeward vortex intensified while the other became weaker. These vortical structures are the traces of streamwise vortices forming upstream, at the slot exit, during the blowing phases. As the jet velocity ratio and the slot yaw angle were increased the vortices grew in size and intensity. The vortex identification technique showed that these vortical structures are intermittently present in the instantaneous flow fields with a percentage growing with the frequency but not influenced by the yaw angle. Conditional averages showed that while the rotational core of the identified vortices is nearly unaffected, their outer region is greatly modified and grows in size and intensity as the jet velocity ratio and the yaw angle increased

Circular cylinder drag reduction using piezoelectric actuators

An active flow control technique based on "smart-tabs" is proposed to delay flow separation on a circular cylinder. The actuators are retractable and orientable multilayer piezoelectric tabs which protrude perpendicularly from the model surface. They are mounted along the spanwise direction with constant spacing. The effectiveness of the control was tested in precritical and in post-critical regime by evaluating the effects of several control parameters of the tabs like frequency, amplitude, height, angular position and plate incidence with respect to the local flow. Measurements of the mean static pressure distribution around the cylinder were used to estimate the pressure drag coefficient. The maximum drag reduction achieved in the pre-critical regime was of the order of 30%, whereas in the post-critical regime was about 10%, 3% of which due to active forcing. Furthermore, pressure fluctuation measurements were performed and spectral analysis indicated an almost complete suppression of the vortex shedding in active forcing condition

Wall-pressure based Multi-Time-Delay Linear StochasticEstimation

Linear Stochastic Estimation (LSE) is a well known, widely used data analysis technique, offering quantitative insight into the dynamics of coherent structures12. In the wall-pressure based classical LSE approach the velocity estimate u(t) is obtained from the wall-pressure p(t) as u(t)_LSE = bo*p(t), i.e. by using a single sam- ple of the wall-pressure time history. By contrast, in the Multi-Time-Delay (MTD) technique more than one past samples is used simultaneously for the estimat

Control of the flow in a trapped vortex cell

A trapped vortex cell, (TVC), is a flow control device consisting in a cavity embedded on the upper surface of an airfoil, designed to trap a steady vortex. By the interaction with the vortical cell's ow, the incoming boundary layer becomes more energetic, and it is thus less prone to separation. Wind tunnel tests by De Gregorio et al. [2] and by Lasagna et al. [1] have shown that to make this control effective the cavity flow itself must be the target of a control action. In particular, the latter authors have shown that the airfoil drag can be substantially reduced with respect to the clean airfoil by applying suction into the cavity region and that this technique is superior to a classical boundary layer suction system, for the same suction flow rate. One goal of this work is to further investigate on the drag reduction mechanism of the TVC with suction technique. Furthermore, a second control technique, based on a synthetic jet device (SJ) which injects momentum into the cavity in order to energize the vortical cell's flow, is considered. Interest in this technique is raised since it is far more effcient than steady suctio