Non equilibrium phase transitions and Floquet Kibble-Zurek scaling

We study the slow crossing of non-equilibrium quantum phase transitions in periodically-driven systems. We explicitly consider a spin chain with a uniform time-dependent magnetic field and focus on the Floquet state that is adiabatically connected to the ground state of the static model. We find that this {\it Floquet ground state} undergoes a series of quantum phase transitions characterized by a non-trivial topology. To dinamically probe these transitions, we propose to start with a large driving frequency and slowly decrease it as a function of time. Combining analytical and numerical methods, we uncover a Kibble-Zurek scaling that persists in the presence of moderate interactions. This scaling can be used to experimentally demonstrate non-equilibrium transitions that cannot be otherwise observed.Comment: 7 pages, 3 figures, Supplemental Material. (In this last version, the one published in EPL, we provide a better discussion of the Floquet adiabatic theorem, the construction of the Floquet ground state as an adiabatic continuation and the nature of the phase transitions.

On the Preliminary Design and Performance Prediction of Centrifugal Turbopumps—Part 2

The ideal flow model for the preliminary design and performance prediction of radial turbopumps presented in the companion paper of the present volume (d’Agostino et al., 2017) is here interfaced with the calculation of the boundary layers inside the blade channels and other major forms of flow losses, with the aim of developing an effective tool for rapid parametric optimization of the machine performance and geometry under appropriate design constraints, such as assigned values of the specific speed, flow coefficient and blade solidity. A mixed-flow turbopump, with a six-bladed impeller, a vaneless diffuser, a single-spiral volute and nondimensional performance characteristics similar to those typically used in liquid propellant rocket engine feed systems, has been designed, parametrically optimized and manufactured in accordance with the indications of the present model. The pumping and suction performance of the machine have been determined in a series of tests in the Cavitating Pump Rotordynamic Test Facility (CPRTF). Under fully-wetted flow conditions the measured pumping characteristics of the machine (hydraulic head and efficiency as functions of the flow coefficient) proved to be in excellent agreement with the model predictions, thus successfully confirming the validity of the proposed model as an effective tool for rapid and efficient design of high-performance centrifugal turbopumps

A Reduced Order Model for Optimal Centrifugal Pump Design

A reduced order model for preliminary design and noncavitating performance prediction of radial turbopumps has been illustrated in a previous paper presented by the same authors. The model expresses the 3D incompressible, inviscid, irrotational flow through helical blades with slow axial variations of the pitch and backsweep by superposing a 2D cross-sectional axial vorticity correction to a fully-guided flow with axisymmetric stagnation velocity in the meridional plane. Application of the relevant governing equations yields a set of constraints for the axial evolution of the blade pitch and backsweep that allows for the closed form definition of the impeller geometry and flowfield in terms of a reduced number of controlling parameters. In turn, mass and momentum conservation are used to account for the mixing of the flow leaving the impeller and its coupling with 2D reduced order models of the flow in the diffuser (if any) and the volute, thus generating the information necessary for completing the geometric definition of the machine and for determining its ideal noncavitating performance in accordance with the resulting flowfield. In the present paper, the above ideal flow model has been interfaced with the calculation of boundary layers inside the blade channels and other major forms of flow losses, with the aim of developing an effective tool for rapid parametric optimization of the machine geometry and performance under appropriate design constraints such as target values of the specific speed, flow coefficient and impeller blading solidity

Cavitation and Flow Instabilities in a 3- Bladed Axial Inducer Designed by Means of a Reduced Order Analytical Model

The present paper illustrates the main results of an experimental campaign conducted using the CPRTF (Cavitating Pump Rotordynamic Test Facility) at Alta S.p.A. The tests were carried out on the DAPAMITO inducer, a three-bladed axial pump designed and manufactured by Alta S.p.A. using a simplified analytical model for the prediction of geometry and noncavitating performance of typical space rocket inducers. The transparent inlet section of the facility was instrumented with several piezoelectric pressure transducers located at three axial stations: inducer inlet, outlet and the middle of the axial chord of the blades. At each axial station at least two transducers were mounted with given angular spacing in order to cross-correlate their signals for amplitude, phase and coherence analysis. However, probably because of the high value of the blade tip clearance, very few flow instabilities have been detected on the inducer, including: steady asymmetric cavitation caused by the different extension of the cavitating regions on the blades; cavitation surge at a frequency equal to 0.16 times the inducer rotational frequency; a higher-order axial phenomenon at 7.2 times the rotational frequency

Experimental Performance of a Tapered Axial Inducer: Comparison with Analytical Predictions

The present paper illustrates the results of an experimental campaign conducted in the CPRTF (Cavitating Pump Rotordynamic Test Facility) at Alta S.p.A. for the characterization of the pumping and suction performance of a three-bladed, tapered-hub, variable-pitch inducer, indicated as DAPAMITO3. The test inducer has been sized and designed by means of the reduced order model recently developed at Alta S.p.A. for the definition of the geometry and the prediction of the non-cavitating performance of typical high-head space rocket inducers. The pumping performance of the inducer proved to be in good accordance with the model predictions. The effects of the blade tip clearance have been investigated and the corresponding performance degradation has been correctly predicted by means of a semi-empirical extension of the model. Finally, the effects of the working fluid temperature on both the non-cavitating and cavitating performance of the inducer have been analysed. At higher ..

DOWN AND DIRTY LOMBROSO’S BORN TO CRIME, THE MORPHOANTHROPOLOGY AND THE IGNORED HUMAN NEUROPHYSIOLOGY: A CRITICAL REVIEW ON A HISTORICAL CONTEXT

Lombroso\u27s theories, in 1800s, gave a strong shock in the international scientific community , regarding the correlation between the human morphology and its tendency to crime. They were followed, especially out of the Europe, and still are being discussed. But, in that century, they were enriched researches on human neurophysiology, which then would be further down to our time and that they denied sharply the Lombroso concepts. In short, the ignored neurophysiology, to the detriment of hypothesis which theorized the tendency to crime as an expression of the physical features of the individual, the whole body, from the face, limbs, ears, the shape of the skull. In this review, are made some critical remarks about Lombroso concepts, on \u27atavism, the people considered inferior on the basis of their physical appearance, in other words what was called morphoanthropology. At the same time, this work emphasizes instead the \u27importance of neurophysiological aspects of\u27 individual tending to crime, that are the basis of abnormal acts against the society \u27and that are related to the dysfunction of certain brain areas, such as the frontal cortex and limbic cortex, under the influence of genotype and environmental factors

Transmission dynamics of the ongoing chikungunya outbreak in Central Italy. From coastal areas to the metropolitan city of Rome, summer 2017

A large chikungunya outbreak is ongoing in Italy, with a main cluster in the Anzio coastal municipality. With preliminary epidemiological data, and a transmission model using mosquito abundance and biting rates, we estimated the basic reproduction number R0 at 2.07 (95% credible interval: 1.47–2.59) and the first case importation between 21 May and 18 June 2017. Outbreak risk was higher in coastal/rural sites than urban ones. Novel transmission foci could occur up to mid-November

Spatial and temporal hot spots of Aedes albopictus abundance inside and outside a South European metropolitan area

Aedes albopictus is a tropical invasive species which in the last decades spread worldwide, also colonizing temperate regions of Europe and US, where it has become a public health concern due to its ability to transmit exotic arboviruses, as well as severe nuisance problems due to its aggressive daytime outdoor biting behaviour. While several studies have been carried out in order to predict the potential limits of the species expansions based on eco-climatic parameters, few studies have so far focused on the specific effects of these variables in shaping its micro-geographic abundance and dynamics. The present study investigated eco-climatic factors affecting Ae. albopictus abundance and dynamics in metropolitan and sub-urban/rural sites in Rome (Italy), which was colonized in 1997 and is nowadays one of the most infested metropolitan areas in Southern Europe. To this aim, longitudinal adult monitoring was carried out along a 70 km-transect across and beyond the most urbanized and densely populated metropolitan area. Two fine scale spatiotemporal datasets (one with reference to a 20m circular buffer around sticky traps used to collect mosquitoes and the second to a 300m circular buffer within each sampling site) were exploited to analyze the effect of climatic and socio-environmental variables on Ae. albopictus abundance and dynamics along the transect. Results showed an association between highly anthropized habitats and high adult abundance both in metropolitan and sub-urban/ rural areas, with “small green islands” corresponding to hot spots of abundance in the metropolitan areas only, and a bimodal seasonal dynamics with a second peak of abundance in autumn, due to heavy rains occurring in the preceding weeks in association with permissive temperatures. The results provide useful indications to prioritize public mosquito control measures in temperate urban areas where nuisance, human-mosquito contact and risk of local arbovirus transmission are likely higher, and highlight potential public health risks also after the summer months typically associated with high mosquito densities