bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Study on Thermal and Fluid Dynamic Behavior of Confined Impinging Slot Jets with Nanofluids in Partially Filled Configuration of Metal Foam
Authors: Buonomo B , di Pasqua A , Manca O , Nappo S 
Published: April 2021

Abstract
In this work a numerical analysis on confined slot impinging jets constituted by a partially filled configuration of metal foam in mixed convection is illustrated. The employed working fluids are pure water or Al2O3/water based nanofluids A two-dimensional model is constructed and several Peclet numbers (equal to 100, 200, 350, 750, 1500) are assumed. Rayleigh numbers is fixed equal to 30000. The nanoparticle volume concentrations are in a range from 0% to 4% and the nanoparticle diameter is considered equal to 30nm. The target surface is characterized by a constant temperature, evaluated according to the value of Rayleigh number. The distance of the target surface is five times greater than the slot jet width. Three different values of ratio between the total system and the metal foam length have been assumed. The thermal and fluid-dynamic properties of nanofluids are estimated by a single-phase model approach. The model of local thermal non equilibrium (LTNE) is assumed in order to replicate the behavior of the metal foam characterized by a number of pores per inch (PPI) equal to 20 and a porosity of 0.9005. Results show increasing values of the convective heat transfer coefficients for increasing values of Peclet number and nanoparticle concentration. This behaviour is more evident at low Peclet number values. In conclusion, the ratio between the thermal and pumping power is calculated in order to find a trade-off between the increase of heat transfer and pressure drop.
Experimental evaluation of the thermal conductivity for additive manufactured materials. New test facility concept and preliminary tests
Authors: Bianco N , Mastrullo R , Mauro A W , Viscito L 
Published: April 2021

Abstract
Items for heat transfer made by metal foams or additive manufactured structures allow to create special components for several applications (i.e. fast response PCM, complex and light HEXs working at high temperatures for the aerospace sector). For their design thermo-physical properties data are required, such as thermal conductivity. To accurately measure this parameter with conventional procedures for metallic items (e.g. flash methods), the specific heat and density should be measured each time depending on the actual composition of the porous media (estimation is not yet reliable and porosity not known). The scope of this paper is to validate a test facility and the relative method for the data reduction to proof the possibility to measure directly the thermal conductivity with samples of small size. The experiments, carried-out with square samples (30×30 mm2), allow to measure a range of thermal conductivity between 5 and 50 W/m K. The main aspect of the experimental method is the calibration of the heat losses towards the environment by means of a reverse technique. The assessment of the results against samples of known materials was good.
Experimental study of mitigation systems to prevent Thermal Runaway of Li-ion Batteries
Authors: D’Annibale Francesco , Menale Carla 
Published: April 2021

Abstract
Li-ion batteries have experienced a widespread deployment due to the strong interest in electrochemical devices capable of storing a large amount of energy in small volumes and supplying high powers when required. However, besides those advantages, this technology still presents several unsolved issues, especially regarding the safety aspects. These devices can, in fact, experience thermal runaway if the generated thermal power is not adequately dispersed, and this can occur when the cell / battery is subjected to abuse conditions (mechanical, electrical or thermal abuses).
The experimental study was carried out using a full-scale hardware simulator, capable of simulating the thermal behavior of a battery pack, where electrically heated elements replaced real Li-ion cells. This expedient guarantees a high reproducibility of the working conditions and consequently a higher reliability of the measured data.
The hardware simulator allows to reproduce the thermal behavior under normal operating conditions, and under abuse conditions which can lead to thermal runaway.
The present work reports the results of the tests that have been carried out by reproducing the abuse conditions in one cell inside a battery module; the abused cell is heated with a high power (from 100 to 500 W for cells with a maximum heat loss of 30 W under normal operating conditions) and the efficiency of different cooling systems is checked both in limiting the temperature of the abused cell and in preventing the propagation of heat to the adjacent cells. In particular, different fluids, different fluid speeds and different mitigation methods have been tested.
SBO analysis of a generic PWR-900 with ASTEC and MELCOR codes
Authors: Maccari Pietro , Mascari Fulvio , Ederli Stefano , Manservisi Sandro 
Published: April 2021

Abstract
After the Fukushima accident, the interest of the public to nuclear safety has growth and the international technical nuclear community has increased his attention in the investigation and the characterization of Severe Accident (SA) scenarios. In order to simulate the different, complex and multi-physical phenomena involved in a SA, computational tools, known as SA codes, have been developed in the last decades. In order to give some insights on the modelling capabilities of these tools and the differences in the calculation results, also related to the user-effect, an analysis of an unmitigated Station Black Out (SBO) occurring in a generic Western three-loops PWR 900 MWe has been carried out by the authors in the framework of the NUGENIA TA-2 ASCOM project. The simulation results of ASTEC code (study carried out with ASTEC V2, IRSN all rights reserved, [2019]), developed by IRSN, and MELCOR 2.2 code, developed by SANDIA for USNRC, have been compared and analyzed. The SBO scenario considered takes into account the intervention of the accumulators as only accident mitigation strategy. Several figures of merits related to the thermal-hydraulic (e.g. primary pressure, cladding temperature, etc.) and to the core degradation (e.g. hydrogen production, etc.) have been considered to describe the accident evolution until the vessel failure, for the two codes comparison.
Propagation of geometric uncertainties in heat transfer problems solved by RBF-FD meshless method
Authors: Zamolo R , Parussini L , Nobile E 
Published: April 2021

Abstract
The design of engineering components must take into account the manufacturing tolerances of production processes since they lead to uncertainties in the behaviour of the products. It is therefore of valuable practical interest to quantify such uncertainties, with particular reference to problems involving geometrical uncertainties of the boundaries. This task is carried out in the present work by coupling the Non-Intrusive Polynomial Chaos (PC) method, employed for the quantification of uncertainties, with a Radial Basis Function Finite Differences (RBF-FD) meshless method, employed for the numerical simulations. The PC method with the Non-Intrusive formulation allows the use of existing deterministic solvers for the accurate prediction of the sought random response, i.e., the statistic moments of the involved variables. The RBF-FD method is therefore employed as a black box solver for the required set of problems defined over deterministic domains. The main advantage of the RBF-FD meshless method over traditional mesh-based methods is its capability of easily deal with practical problems defined over complex-shaped domains since no traditional mesh is required. The geometrical flexibility of the RBF-FD is even more advantageous in the context of geometric uncertainty quantification with the Non-Intrusive PC method since different solutions over different geometries are required. The applicability of the proposed approach to practical problems is then presented through the prediction of geometric uncertainty effects for a tube heat exchanger under natural convection where a 2D steady incompressible flow is considered.
Thermal characterisation of Triple Concentric Tube Heat Exchangers by applying parameter estimation: direct problem implementation
Authors: Vocale P , Malavasi M , Cattani L , Bozzoli F , Pelacci M , Rainieri S 
Published: April 2021

Abstract
Heat transfer enhancement in heat exchangers’s design represents a key technological challenge because of the increase in the cost of energy and raw materials. A promising technology is represented by the triple tube heat exchangers, in which the heat transfer is enhanced in comparison with the traditional double tube heat exchangers, due to the larger heat transfer area per unit length. Among the different methodologies that can be adopted to assess the performance of the triple tube heat exchangers, parameter estimation procedure represents a promising tool, since it has been successfully applied in many disciplines of engineering. To apply this inverse technique, it is mandatory defining the direct problem, which for the issue here addressed allows evaluating the outlet temperatures of the fluids flowing in the heat exchanger. Since in a triple tube heat exchanger there are three fluids, the approach based on the evaluation of the logarithmic mean temperature difference is no longer valid and an alternative procedure has to be followed. In the present analysis a numerical model for the performance evaluation of triple tube heat exchangers is presented. The validation of the proposed numerical model, carried out by adopting the analytical model available in literature, highlights that the model can be considered accurate and reliable. Moreover, the computational time required to solve the set of equations is very limited.
Preliminary analysis of the influence of environmental boundary conditions on convective heat transfer coefficients
Authors: Evangelisti Luca , Guattari Claudia , Rubeis Tullio de 
Published: April 2021

Abstract
In this contribution, a hot box apparatus was used to investigate convective heat transfers through an experimental setup composed of a heat-flow sensor, air and surface temperature probes installed on the wall tested in the hot box and a hot-wire anemometer. The air near the wall was indirectly moved by means of a forced convection system through which the air velocity can be modified to simulate different environmental conditions. The hot box apparatus was used in order to investigate the influence of the air velocity on internal convective heat transfer coefficients (hc), under natural/mixed convection conditions. The Standard ISO 6946 suggests a typical internal convective heat transfer coefficient equal to 2.5 W/m2K when horizontal heat fluxes occur. No detailed information about this value are reported in the Standard. So, the final aim of this study is to assess the applicability of the internal convective heat transfer coefficient value proposed by ISO 6946 under different air velocity values, quantifying how hc varies as air velocity changes.
Environmental Effect on Temperature Measurement in Natural Gas Network Balance
Authors: Arpino F. , Canale L. , Cortellessa G. , D’Alessio R. , Dell’Isola M. , Ficco G. , Moretti L. , Vigo P. , Zuena F. 
Published: April 2021

Abstract
Accurate temperature measurements are essential for accounting and balancing natural gas in transmission and distribution networks. In fact, in order to convert the gas volumes measured at operational conditions into standard reference ones, the accurate knowledge of both the thermodynamic conditions of the gas (i.e. temperature and pressure) and its chemical composition is necessary. In the case of large flow-meters, even small measurement errors (e.g. deriving from difference between the ambient temperature and the temperature of the fluid) can become relevant in terms of “unaccounted for gas”, especially when they do not find adequate compensation during the annual balancing of the network. To this aim it is necessary to carefully evaluate the systematic errors affecting temperature measurement which depend on instrumentation metrological characteristics as well as on thermo-fluid dynamic issues. In some cases, thermal insulation of the flow-meter and both upstream and downstream measuring stretches should be necessary. In this paper the authors present the results of an experimental study on the installation effects of temperature probes in closed conduits, performed at different operating conditions of natural gas transmission networks and aimed at estimating the typical random and systematic effects, and proposing optimal installation and operative solutions.
Influence of the Thermophysical Model on the CFD Analysis of Oil-Cooled Transformer Windings
Authors: Salerno Elisabetta , Leonforte Adriano , Angeli Diego 
Published: April 2021

Abstract
A disc-type winding of an oil-immersed power transformer is modeled with Computational Fluid Dynamics. Different approaches are implemented to evaluate the feasibility of the Boussinesq approximation: (i) constant fluid properties, (ii) variable viscosity and thermal diffusivity and (iii) temperature-dependent fluid properties. Temperature and flow distributions are reconstructed and put into relation with physical phenomena and model assumptions. Their comparison suggests that numerical results are fairly sensitive to the thermophysical model as long as the buoyancy force is a relevant component of the flow. Nonetheless, all the cases converge to very close predictions of the hot-spot value and location, with possibly positive implications for the use of reference parameters when deriving flow and heat transfer correlations for this topic.
Biophysical and policy factors predict simplified crop rotations in the US Midwest
Authors: Socolar Yvonne , Goldstein Benjamin R , de Valpine Perry , Bowles Timothy M 
Published: April 2021

Abstract
Over 70% of the 62 million hectares of cropland in the Midwestern United States is grown in corn-based rotations. These crop rotations are caught in a century-long simplification trend despite robust evidence demonstrating yield and soil benefits from diversified rotations. Our ability to explore and explain this trend will come in part from observing the biophysical and policy influences on farmers’ crop choices at one key level of management: the field. Yet field-level crop rotation patterns remain largely unstudied at regional scales and will be essential for understanding how national agricultural policy manifests locally and interacts with biophysical phenomena to erode—or bolster—soil and environmental health, agricultural resilience, and farmers’ livelihoods. We developed a novel indicator of crop rotational complexity and applied it to 1.5 million fields across the US Midwest. We used bootstrapped linear mixed models to regress field-level rotational complexity against biophysical (land capability, precipitation) and policy-driven (distance to the nearest biofuel plant and grain elevator) factors. After accounting for spatial autocorrelation, there were statistically clear negative relationships between rotational complexity and biophysical factors (land capability and precipitation during the growing season), indicating decreased rotation in prime growing areas. A positive relationship between rotational complexity and distance to the nearest biofuel plant suggests policy-based, as well as biophysical, constraints on regional rotations. This novel RCI is a promising tool for future fine-scale rotational analysis and demonstrates that the United States’ most fertile soils are the most prone to degradation, with recent policy choices further exacerbating this trend.
An enhanced periosteum structure/function dual mimicking membrane for in-situ restorations of periosteum and bone
Authors: Laijun Liu , Yu Zhang , Chaojing Li , Jifu Mao , Fujun Wang , Lu Wang 
Published: April 2021

Abstract
Periosteum plays a pivotal role in bone formation and reconstruction. The ideal repair process for critical-size bone defects with periosteum damage is to induce regeneration of periosteum tissue and the subsequent bone regeneration derived by the periosteum. Inspired by the bilayer structure of the natural periosteum, we develop a periosteum structure/function dual mimicking membrane for the in-situ restoration of periosteum and bone tissue. Among them, the macroporous fluffy guiding layer (TPF) simulates the fibrous layer of the natural periosteum, which is conducive to infiltration and oriented growth of fibroblasts. And the extracellular matrix-like bioactive layer (TN) simulates the cambium layer of the natural periosteum, which significantly enhances the proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells. A middle dense layer (PC) connects the above two layers and has the function of preventing the invasion of soft tissues while enhancing the biomimetic periosteum. In vivo restoration results show that the tri-layer biomimetic periosteum (TPF/PC/TN) has an outstanding effect in promoting the regeneration of both vascularized periosteum and bone at the same time. Therefore, the enhanced biomimetic periosteum developed in this research has a great clinical value in the efficient and high-quality reconstruction of critical-size bone defects with periosteum damage.
Surface Physical Properties of Ion Beam Sputtered Copper Thin Films on Poly Tetrafluoroethylene
Authors: Atta A , Abdeltwab E , Bek A 
Published: April 2021

Abstract
In this study thin copper (Cu) films are deposited on poly tetrafluoroethylene (PTFE) substrate using ion beam sputtering technique. The films are characterized using Raman spectroscopy, UV–VIS spectroscopy and atomic force microscope (AFM) techniques. The Raman spectrum shows some decrease in the intensities of Raman bands for Cu/PTFE film than pristine PTFE. UV–VIS transmittance spectra display that the optical transmission reduces from ~75% for pristine PTFE to ~0.20% after 60 min of deposition due to Cu nanoparticles dispersed in PTFE. The surface roughness is increased from 39.4 nm for PTFE to 75.9 nm, while the adhesion force is increased from 9.6 nN to 14.7 nN and Young’s modulus is enhanced from 0.58 GPa to 1.46 GPa after 40 min of Cu deposition time. The DC electrical conductivity at an applied voltage of 200 V is improved from 3.88 × 10–8 S.cm−1 for PTFE to 5.3 × 10–8 S.cm−1 after 60 min of deposition at room temperature. The fabricated Cu/PTFE films exhibit excellent surface properties, which demote that Cu/PTFE films could serve as a low cost material for a broad range of electrical and charge storing devices.
Microstructure and fatigue damage mechanism of 6082-T6 aluminium alloy welded joint
Authors: Zhu Minqi , Yang Shanglei , Bai Yishan , Fan Cong 
Published: April 2021

Abstract
In this paper, 6mm thick 6082-T6 high-strength aluminium alloy is taken as the research object, and CLOOS ROMAT-3500 industrial robot MIG welder is used for welding. High-cycle fatigue test is carried out on welded joint and 6082-T6 base metal. Microstructure, microhardness, tensile properties and fatigue properties are studied, and fatigue fracture is observed and analyzed. The test results show that: equiaxed crystals exist in the center of the weld. Broken equiaxed crystals are found in the weld due to stirring in the molten pool, a large number of pore and columnar crystal layers are found at the junction of the two beads. A small amount of pore and cellular dendrite are found in the fusion zone. A softening zone with a minimum hardness of 65.5HV exists in the heat affected zone(HAZ). The conditional fatigue limits for base metal and weld specimens are 77.26MPa and 48.69MPa at the set target cycle of 107 respectively. In fatigue fracture, there are a lot of cleavage fracture characteristics and ductile fracture characteristics. The crack initiation is quasi-cleavage fracture characteristic. In the past studies, I have studied the fatigue life of joints, but as the research progresses, I believe that the fatigue behavior and fatigue damage mechanism plays an important role in fatigue life. In this paper, Fatigue fracture process is analyzed by correlation calculation of stress intensity factor. Two crack initiation modes are proposed based on the welding process. The first is fatigue crack initiation caused by stress concentration at the grain boundary where hydrogen elements converged, the second is fatigue crack initiation caused by the gap between equiaxed and columnar crystals inside and outside the central pore of the weld.
Surface characteristics and osteocompatibility of titanium preserved in a ZnS@BSA-containing storage solution
Authors: Tang Zehua , Tang Kaiming , Liu Yao , Zhu Wenqing , Qiu Jing 
Published: April 2021

Abstract
This study aimed to the preparation of a storage solution containing zinc sulfide particles encapsulated in bovine serum albumin (ZnS@BSA) and its application to improve surface characteristics and osteocompatibility of pure and SLA titanium surfaces. The analysis of surface characteristics including surface topography, elemental distribution and protein amounts confirmed that ZnS@BSA particles were successfully adsorbed on the two titanium surfaces without changing the original morphology. Assays of wettability showed that titanium surfaces preserved in ZnS@BSA solution had superior hydrophilicity compared with control groups. In vitro experiments demonstrated that the titanium surfaces preserved in ZnS@BSA solution significantly promoted the proliferation, adhesion and differentiation of MC3T3-E1 cells. The study therefore concluded that the ZnS@BSA solution could improve the bioactivity of titanium surface and exhibit the potential to be a new type of titanium implant storage solution.
A generalized framework for analytic regularization of uniform cubic B-spline displacement fields
Authors: Shah Keyur D , Shackleford James A , Kandasamy Nagarajan , Sharp Gregory C 
Published: April 2021

Abstract
Image registration is an inherently ill-posed problem that lacks the constraints needed for a unique mapping between voxels of the two images being registered. As such, one must regularize the registration to achieve physically meaningful transforms. The regularization penalty is usually a function of derivatives of the displacement-vector field and can be calculated either analytically or numerically. The numerical approach, however, is computationally expensive depending on the image size, and therefore a computationally efficient analytical framework has been developed. Using cubic B-splines as the registration transform, we develop a generalized mathematical framework that supports five distinct regularizers: diffusion, curvature, linear elastic, third-order, and total displacement. We validate our approach by comparing each with its numerical counterpart in terms of accuracy. We also provide benchmarking results showing that the analytic solutions run significantly faster—up to two orders of magnitude—than finite differencing based numerical implementations.