bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parametric thermal analysis for the optimization of Double Walled Tubes layout in the Water Cooled Lithium Lead inboard blanket of DEMO fusion reactor
Authors: Arena Pietro , Del Nevo Alessandro , Alessandro Di Maio Pietro , Forte Ruggero , Nevone Giulio 
Published: May 2019

Abstract
Within the roadmap that will lead to the nuclear fusion exploitation for electric energy generation, the construction of a DEMOnstration (DEMO) reactor is, probably, the most important milestone to be reached since it will demonstrate the technological feasibility and economic competitiveness of an industrial-scale nuclear fusion reactor. In order to reach this goal, several European universities and research centres have joined their efforts in the EUROfusion action, funded by HORIZON 2020 UE programme. Within the framework of EUROfusion research activities, ENEA and University of Palermo are involved in the design of the Water-Cooled Lithium Lead Breeding Blanket (WCLL BB), that is one of the two BB concepts under consideration to be adopted in the DEMO reactor. It is mainly characterized by a liquid lithium-lead eutectic alloy acting as breeder (lithium) and neutron multiplier (lead), as well as by subcooled pressurized water as coolant. Two separate circuits, both characterized by a pressure of 15.5 MPa and inlet/outlet temperatures of 295 °C/328 °C, are deputed to cool down the First Wall (FW) and the Breeder Zone (BZ). The former consists in a system of radial-toroidal-radial C-shaped squared channels where countercurrent water flow occurs while the latter relies in the use of bundles of poloidal-radial Double Walled Tubes (DWTs) housed within the breeder.
A parametric thermal study has been carried out in order to assess the best DWTs’ layout assuring that the structural material maximum temperature does not overcome the allowable limit of 550 °C and that the overall coolant thermal rise fulfils the design target value of 33 °C. The study has been performed following a theoretical-numerical approach based on the Finite Element Method (FEM) and adopting the quoted Abaqus FEM code. Main assumptions and models together with results obtained are herewith reported and critically discussed.
On the thermal dynamic behaviour of the helium-cooled DEMO fusion reactor
Authors: Moscato Ivo , Barucca Luciana , Ciattaglia Sergio , Alessandro Di Maio Pietro 
Published: May 2019

Abstract
The EU-DEMO conceptual design is being conducted among research institutions and universities from 26 countries of European Union, Switzerland and Ukraine. Its mission is to realise electricity from nuclear fusion reaction by 2050. As DEMO has been conceived to deliver net electricity to the grid, the choice of the Breeding Blanket (BB) coolant plays a pivotal role in the reactor design having a strong influence on plant operation, safety and maintenance. In particular, due to the pulsed nature of the heat source, the Primary Heat Transfer System (PHTS) becomes a very important actor of the Balance of Plant (BoP) together with the Power Conversion System (PCS). Moreover, aiming to mitigate the potential negative impact of plasma pulsing on BoP equipment, for the DEMO plant is also being investigated a “heat transfer chain” option which envisages an Intermediate Heat Transfer System (IHTS) equipped with an Energy Storage System (ESS) between PHTS and PCS. Within this framework, a preliminary study has been carried out to analyse the thermal dynamic behaviour of the IHTS system for the Helium-Cooled Pebble Bed (HCPB) BB concept during pulse/dwell transition which should be still considered as the normal operating mode of a fusion power plant. Starting from preliminary thermal-hydraulic calculations made in order to size the main BoP components, the global performances of DEMO BoP have been quantitatively assessed focusing the attention on the attitude of the whole IHTS to smooth the sudden power variations which come from the plasma. The paper describes criteria and rationale followed to develop a numerical model which manages to simulate simple transient scenarios of DEMO BoP. Results of numerical simulations are presented and critically discussed in order to point out the main issues that DEMO BoP has to overcome to achieve a viable electricity power output.
Use of multispectral and thermal imagery in precision viticulture
Authors: Tanda G , Chiarabini V. 
Published: May 2019

AbstractThe increasing demand for higher quality and yield of wine production has led to a growing interest in precision viticulture, i.e., practices of monitoring and managing spatial variations in variables related to productivity within a vineyard. This paper presents a few applications of optical measurements, in combination with monitoring systems making use of geolocation and remote/proximal sensing, to calculate vegetation indices related to plant vigour and water stress in vineyards. Measurements were performed on vineyards in Burgenland, Austria, by both aerial and proximal (terrestrial) sensing techniques. A remote-sensing, four-band multispectral sensor, placed on an Unmanned Aerial Vehicle (UAV), has been used to detect the spectral signature of the vineyard and to calculate the NDVI index, useful to selectively address the harvest on the basis of quality and quantity of grapes. Proximal, thermal infrared imaging complemented the investigation providing information about the water status of the vegetation through the CWSI index. Examples of vigour maps are provided, showing, inside a given parcel, the presence of canopies at different level of vegetation characteristics. Results provide a range of information useful to make the optimal choice in management strategies of vineyards.
Experimental study of liquid velocity profiles in large-scale bubble columns with particle tracking velocimetry
Authors: Besagni G , Inzoli F , Zieghenein T , Lucas D 
Published: May 2019

Abstract
A complete knowledge of the bubble column fluid dynamics relies on understanding the global and the local fluid dynamic properties. Unfortunately, most of the previous literature focused on the “global-scale” fluid dynamics, whereas a limited attention was devoted to the “local-scale”. We contribute to present-day discussion by proposing an experimental study concerning the local liquid velocity profiles within the pseudo-homogeneous flow regime. The experimental study, based on a particle-identification and particle-tracking algorithm, was conducted in a large-diameter and large-scale bubble column (height equal to 5.3 m; inner diameter equal to 0.24 m) operated in the counter-current mode. We considered gas superficial velocities in the range of 0.37-1.88 cm/s and liquid superficial velocities up to −9 cm/s. Time-averaged and transient liquid velocity fields were obtained for five superficial gas velocities and four superficial liquid velocities at two measuring heights. Subsequently, the liquid velocity observations were coupled with previously measured bubble size distributions and local void fractions, to provide a complete description of the “local-scale” fluid dynamics. These data would help in the validation procedure of numerical codes, to support the prediction of industrial-scale relevant conditions.
Condensation heat transfer in minichannels: a review of available correlations
Authors: Azzolin M , Berto A , Bortolin S , Del Col D 
Published: May 2019

Abstract
Heat exchangers with enhanced performance are demanded in various engineering applications. Very often heat transfer devices are requested to guarantee not only high heat transfer coefficients but also small size and weight, thus limiting the charge of the operative fluid inside the heat exchanger. In order to increase the performance of condensers and to properly design new heat exchangers, it is essential to have predictive tools that are validated with experimental data. Sometimes, even well established semi-empirical correlations can be inaccurate in some microscale flow conditions or with new refrigerants. The present paper starts from the experimental database measured during condensation with different fluids (pure fluids and refrigerant blends) inside small channels (hydraulic diameter around 1 mm) at the Department of Industrial Engineering of the University of Padova. A critical review of available correlations for heat transfer during condensation in minichannels is presented. Predictions of heat transfer coefficients obtained applying selected models are compared with the experimental database that covers various refrigerants: hydrofluorocarbons (HFC, i.e. R32 and R134a), new hydrofluoroolefins (HFOs) with low global warming potential (R1234ze(E)), natural refrigerants (hydrocarbons such as propane) and zeotropic refrigerant blends of HFCs and HFOs (R32/R1234ze(E)). Refrigerant mixtures are studied because for some applications they may be a proper solution. For instance in the air-conditioning industry there are not drop-in pure fluids to replace the high global warming potential (GWP) fluids currently employed (e.g. R410A). Unfortunately, the design of condensers working with zeotropic mixtures poses the additional problem to account for the mass transfer resistance that leads to a penalization of the heat transfer coefficient. Experimental data are necessary for the assessment of predicting correlations that can be used with these new refrigerants blends.
Numerical study on latent thermal energy storages with PCM partially filled with aluminium foam
Authors: Buonomo Bernardo , Ercole Davide , Manca Oronzio , Nardini Sergio 
Published: May 2019

Abstract
A numerical investigation on the effects of the metal foam into the Latent Heat Thermal Energy Storage System, based on a phase change material, is accomplished. The geometry of the system is a rectangular box heated from below. The PCM is completely embedded in the rectangular box, it is pure paraffin wax with a low value of thermal conductivity and it melts in a range of temperatures. The metal foam is made of copper and it partially fills the rectangular box in order to understand the optimal filling ratio of the foam to have the better thermal performance. The enthalpy-porosity theory is employed to simulate the phase change of the PCM and the metal foam is modelled as a porous media that follow the Brinkman-extended Darcy model. The results are shown in term of melting time, temperature and energy at varying of time or at varying the filling height ratio.
Experimental investigation on flow boiling heat transfer and pressure drop of refrigerants R32 and R290 in a stainless steel horizontal tube
Authors: Citarella B , Lillo G , Mastrullo R , Mauro A W , Viscito L 
Published: May 2019

Abstract
The purpose of this paper is to present new flow boiling heat transfer and pressure drop data in a single, horizontal smooth stainless steel tube of 6.0 mm internal diameter, in which R32 and R290 (propane) are employed as working fluids. The cross sectional average heat transfer coefficients are obtained by measuring the temperatures at the top, bottom, left and right sides of the channel. The experimental trends are analyzed for different operating conditions in terms of mass velocity (from 150 to 300 kg/(m2 s)) and heat flux (from 10 to 40 kW/m2). The saturation temperature is fixed to 25 °C for the heat transfer data and to 25 and 35 °C for the pressure drop experiments. The effects of the operative parameters and of the working fluids on local heat transfer coefficients and frictional pressure drop are discussed and the experimental data are finally compared with some of the available correlations taken from scientific literature.
Convective and absolute instability of horizontal flow in porous media
Authors: Barletta Antonio , Celli Michele 
Published: May 2019

Abstract
The onset of instability in flow systems has a dual nature depending on the dynamics of the growing normal modes. When the time evolution of a wave packet perturbation is tested, the growth of individual Fourier normal modes can be concealed to an observer in the laboratory reference frame. The reason is that the growing mode can be convected away by the basic flow, so that no effective growth is detected for the wave packet. The convective instability just focusses on the dynamics of each Fourier mode of perturbation, disregarding the actual amplitude growth of a wave packet, measured at a given position. When not only the Fourier modes, but all localised wave packets grow in time at a given position, then the instability becomes absolute. The two types of instability are generally distinct. This paper illustrates the transition from convective to absolute instability starting from a simple one-dimensional case. Then, this concept is employed for the stability analysis of a porous medium flow with heating from below. While the one-dimensional flow system is studied analytically, the porous medium flow stability is investigated numerically.
Experimental investigation on the convective heat transfer enhancement in tubes with twisted-tape inserts
Authors: Bozzoli F , Cattani L , Mocerino A , Rainieri S , Pagliarini G 
Published: May 2019

Abstract
Passive heat transfer enhancement techniques are one of the most interesting approaches to increase the thermal efficiency of heat transfer apparatuses since they do not require external power. Between them, twisted-tape inserts are a very economical technique that can be easily installed in an already working plant in order to increase its thermal performance. The aim of the present work is to experimentally investigate the heat transfer augmentation mechanism induced by the insertion of twisted tapes. The heat transfer performance of the twisted-tape inserts is compared with that of coiled pipes, whose effect on heat transfer is based on the onset of swirl components into the flow as it happens for twisted tapes devices. The two heat transfer enhancement mechanisms have been deeply investigated by using different fluids in order to obtain a robust comparison both for the laminar and the turbulent flow regime.
Experimental and numerical study on a lab-scale latent heat storage prototype for cooling applications
Authors: Caliano M , Bianco N , Graditi G , Mongibello L 
Published: May 2019

Abstract
Latent thermal energy storage systems using phase change materials (PCMs) represent an effective way of storing thermal energy because of high-energy storage density and the isothermal nature of the storage process. In the current study, the charging and discharging characteristics of a lab-scale latent heat storage (LHTES) prototype for cooling applications are experimentally and numerically studied. Two numerical models are developed to analyse the performance characteristics of the LHTES prototype: a conductive model and a conductive-convective model. Effective heat capacity (EHC) method is implemented to consider the latent heat of the phase change material. The governing equations involved in the models are solved using the finite element based software product, COMSOL Multiphysics, and the initial and the boundary conditions are determined on the basis of the data obtained from the experimental tests. Numerically predicted temperature variations of the models during charging and discharging processes are compared with the experimental data extracted from the lab-scale LHTES prototype, and a good agreement between them is found when the conductive-convective model is used, while high deviation is observed in case of use of the conductive model. Other results are presented in terms of the performance parameters such as charging/discharging time, energy storage charge/discharge rate, and melt fraction.
Dry deposition of particle on urban areas
Authors: Giardina M , Buffa P , Cervone A , Lombardo C 
Published: May 2019

Abstract
Dry deposition process is recognized as an important pathway among the removal processes of radioactive pollutants in atmosphere. There is not a unique and accepted theoretical description of involved dry deposition phenomena due to the complexity of the fluid-dynamic processes that influence the deposition flux, but also because there is a lack of experimental data covering all scenarios of interest. In this paper, that is the result of a National Research Program a research activity conducted by DEIM Department of the University of Palermo and ENEA and funded by the Italian Minister of Economic Development, a new schema for parameterization of particle dry deposition velocity on urban area is proposed. The work required comparisons with some experimental data reported in literature for different particle deposition scenarios. The results show that the proposed approach can catch some aspects of phenomena involved in dry deposition processes for the examined environmental conditions with good agreements.
A Further Study of the Mixing of Relativistic Ideal Gases with Relative Relativistic Velocities: The Hot Plasma in the Sun’s Corona, the Type II Spicules and CMEs.
Authors: Gonzalez-Narvaez R E , Díaz-Figueroa E E , de Parga G Ares 
Published: May 2019

Abstract
The Redefined Relativistic Thermodynamics and the conservation of the 4-vector energy-momentum predict a tremendous increment of the temperature after mixing two gases with relative sub-relativistic velocity. This phenomenon can be used to describe the heating of a cold clump with shocked jets material and to predict an improving of the ignition in a Tokamak by injecting a plasma with a sub-relativistic velocity. First, by using the same effect, the mixing of the type II spicule and Coronal Mass Ejections with the plasma of a cold Sun’s corona will explain the increase temperature of the Sun’s corona. Second, considering, in agreement with the observations, that a part of the type II spicule, fall off into the Chromosphere and that the rest of the type II spicule that shocks with the Sun’s corona possesses a higher average relative velocity, the mixing of such a part and the plasma in the Sun’s corona will maintain the high temperature of the Sun’s corona. Moreover, the shock of Coronal Mass Ejections with the Sun’s corona it is a energy source to maintain the high temperature of the Sun’s corona too.
Radial Acceleration and Tully-Fisher Relations in Conformal Gravity
Authors: O’Brien James G. , Chiarelli Thomas L. , Mannheim Philip D. , Falcone Mark A. , AlQurashi Muhannad H. , Carter Jordan 
Published: May 2019

Abstract
In 2016 McGaugh, Lelli and Schombert established a universal Radial Acceleration Relation for centripetal accelerations in spiral galaxies. Their work showed a strong correlation between observed centripetal accelerations and those predicted by luminous Newtonian matter alone. Through the use of the fitting function that they introduced, mass discrepancies in spiral galaxies can be constrained in a uniform manner that is completely determined by the baryons in the galaxies. Here we present a new empirical plot of the observed centripetal accelerations and the luminous Newtonian expectations, which more than doubles the number of observed data points considered by McGaugh et al. while retaining the Radial Acceleration Relation. If this relation is not to be due to dark matter, it would then have to be due to an alternate gravitational theory that departs from Newtonian gravity in some way. In this paper we show how the candidate alternate conformal gravity theory can provide a natural description of the Radial Acceleration Relation, without any need for dark matter or its free halo parameters. We discuss how the empirical Tully-Fisher relation follows as a consequence of conformal gravity.
Critical Scaling and a Dynamical Higgs Boson
Authors: Mannheim Philip D. 
Published: May 2019

Abstract
In a quantum electrodynamics theory that is realized by critical scaling and anomalous dimensions, the action is not chiral invariant and there are no dynamical Goldstone or Higgs boson bound states. In the mean-field approximation to a chiral invariant four-fermion theory the associated mean-field sector action is not chiral invariant either and it also possesses no dynamical bound states, with Goldstone and Higgs bosons instead being generated by an accompanying four-fermion residual interaction. In this paper we show that if a critical scaling electrodynamics in which the dimension d

θ
of

ψ
¯

ψ is reduced from three to two is augmented with a four-fermion interaction, precisely because it possesses no dynamical bound states the electrodynamic sector can be reinterpreted as a mean-field approximation to a larger theory that is chiral symmetric. And with d

θ
= 2 we show in this larger theory there is a residual interaction that then does generate dynamical Goldstone and Higgs bosons in scattering amplitudes that are completely finite. While the dynamically generated Goldstone boson is massless, the dynamically induced Higgs boson is found to be a narrow resonance just above threshold, with its width being a diagnostic that could potentially enable one to distinguish between a dynamical Higgs boson and an elementary one.
Maxwell’s Equations, Fields or Potentials?
Authors: Gersten Alexander , Moalem Amnon 
Published: May 2019

Abstract
Fields and potentials of Maxwell’s Equations transform differently under the Lorentz transformation. Electric and magnetic fields are tridimensional objects which transform like massless fields as a subgroup of the Lorentz group. On the other hand, potentials are four-vectors. Therefore interactions of the electromagnetic fields with four-currents of massive particles cannot be achieved with fields, but only with potentials. Thus potentials seemed to be preferable and a correction to Maxwell’s equations seemed unavoidable. We have generalized the Maxwell’s equations, with 4-vector fields to allow interaction with currents. We suggest a new way to define the potentials and relate them to the new fields.
On the motion of microscopic bodies and observation of position in quantum theory
Authors: Kryukov Alexey A. 
Published: May 2019

Abstract
Newtonian and Scrödinger dynamics can be formulated in a physically meaningful way within the same Hilbert space framework. The resulting unexpected relation between classical and quantum motions goes beyond the results provided by the Ehrenfest theorem. The normal probability distribution and the Born rule turn out to be related. Here a dynamical mechanism responsible for the latter formula is proposed and applied to measurements of macroscopic and microscopic systems. A new meaning of the wave function collapse is proposed. The results are used to explore the classical behavior of macroscopic bodies in quantum theory.
Carrying Capacity of Diving Tourism in Dampier Strait Marine Conservation Area – District of Raja Ampat
Authors: Papilaya Renoldy L , Boli Paulus , Nikijuluw Victor P H 
Published: May 2019

Abstract
Raja Ampat has biodiversity in marine waters so it qualifies as a conservation area as well as a tourism destination. The number of tourist visits to this area has increased significantly, from 998 people in 2007 to 29,653 people in 2016. Increasing number of tourists have become a threat if the behavior of tourist are not concerned on the environment sustainability and damage the attractions for diving. Assessment of the carrying capacity of the area becomes an important factor to know for sure the maximum number of visitors that can be accommodated by the region at any given time without causing disturbance to the environment and human. The study was conducted from September 2015 to August 2016. Data collection of dive sites was conducted by measuring the extent of coral reefs, coral slope, coral reef condition, and water depth. Calculation of carrying capacity used is Physical Carrying Capacity (PCC) and Real Carrying Capacity (RCC). There are 15 main dive sites frequented by divers. The number of people allowed to dive based on physical carrying capacity ranges from 20 to 500 diver/day, for Actual carrying capacity (RCC) of 14 - 335 diver/day. Locations that have the lowest carrying capacity on The Passage site and highest on the Melissa Garden site. The process of integrating dive attractions with other tours and monitoring of travel activities is a key factor in the sustainability of Raja Ampat regency tourism.