bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the convective coefficient on the determination of thermal transmittance through outdoor infrared thermography
Authors: Nardi I , de Rubeis T , Paoletti D , Ambrosini D
Published: September 2020

Several studies and correlations for the convective heat transfer coefficient (CHTC) are available in literature and in handbooks, depending on type of convection, wind speed range or on the test rigs from which they are derived.

The importance of accurate evaluation of CHTC, especially at the building façades, has been highlighted in the recent years, due to the need for reliable measurement of buildings’ heat transfer capability. This study aims at underlining the importance of proper CHTC values for the determination of the building envelope thermal transmittance (U-value) via infrared thermography (IRT). To this scope, firstly an overview on convective heat transfer coefficient is given; then, some CHTC models, chosen from literature, are analyzed at different wind speed classes. Subsequently, such models are employed in two formulas proposed in literature for the U-value measurement via IRT, by using data from previous experimental campaign carried out in controlled environment. Results were compared, and significant deviations were found: one of the employed approaches and formulation is less sensitive to the correlation adopted for the convection expression, amongst those considered and in the wind speed range analyzed. This constitutes an advantage, since one of the weak points of the IRT method is the convection expression itself.
Infrared image processing for local convective heat transfer measurements in rib-enhanced channels
Authors: Vitali L , Gramazio P , Fustinoni D , Vignati F , Niro A
Published: September 2020

In the context of an experimental study designed to retrieve the local heat transfer characteristics in closed channels with ribs in several configurations by IR thermography, a filtering strategy must be adopted to calculate the laplacian of the temperature field, to remove not only Gaussian noise, but also unwanted local features due to the pattern of the conductors of the heater. In this paper, these issues are addressed with a comparative analysis on filtering and interpolation techniques, in particular mean filtering, local surface fitting and cubic smoothing splines, which are carried out by showing their influence on the smoothed thermogram and on the laplacian of the temperature field. The use of cubic smoothing splines gives the best approximation of the temperature field with respect to the mean filter, which alters the temperature field in proximity of the ribs, and to surface interpolation. However, the only filter among those tried that gives meaningful derivatives on the whole image is the mean filter, with a kernel size equal or bigger to that of the spatial feature to be filtered. The resulting derivative also need further filtering to reduce local spikes induced by the filtering operations.
Experimental study of a natural circulation loop and RELAP5-3D analysis
Authors: Bertani C , Falcone N , Bersano A , Azzarone A , De Salve M , Panella B
Published: September 2020

Passive safety systems, which are being largely adopted in advanced nuclear reactors to enhance the safety of the plant, are often based on natural circulation for the decay heat removal and are characterized by the presence of non-condensable gases and pools with stagnant liquid at atmospheric pressure. At the Energy Department of Politecnico di Torino (Italy), the test facility PROPHET has been designed and operated with water in both single-phase and two-phase flow. It consists of a bayonet heat exchanger electrically heated at constant power, a condenser immersed in a pool containing a fixed initial mass of water and the connecting pipes. The effect of loop filling ratio and condenser shell-side level on the system behaviour are here studied. The experimental transients have been analysed in terms of phenomenological windows. Heat losses and the heat sink influence both the time behaviour and the final values of pressure and temperatures in the facility; the filling ratio determines the kind of natural circulation (single-phase or two-phase) and strongly affects the phenomena occurring during the experiments. The experimental results are also compared with the predictions of a RELAP5-3D model. Discrepancies between calculated and experimental values are estimated during the transients in order to evaluate the code prediction capabilities.
Preliminary neutron kinetic – thermal hydraulic coupled analysis of the ALFRED reactor using PHISICS/RELAP5-3D
Authors: Ciurluini Cristiano , Narcisi Vincenzo , Giannetti Fabio , Cretara Luca , Caruso Gianfranco
Published: September 2020

The development of a lead-cooled fast reactor (LFR) demonstrator was proposed, mainly in EU, to investigate the feasibility of an industrial size ELFR (European Lead-cooled Fast Reactor). The demonstrator, called ALFRED (Advanced Lead-cooled Fast Reactor European Demonstrator), consists of a pool-type lead-cooled fast reactor, with a nominal thermal power of 300 MWt. This paper aims to verify the capability of the PHISICS/RELAP5-3D coupled approach to simulate transients of such reactor and to evaluate the effects of accidental scenarios relevant for the safety analysis on the system thermal-hydraulics and on the core power spatial evolution. RELAP5-3D©, developed at Idaho National Laboratory (INL), is a thermal-hydraulic system code, validated for a wide range of transient simulations. The code provides the possibility to simulate innovative working fluids (such as lead and lead alloys) and to use a fully integrated multi-dimensional nodalization. In addition, the need to study complex neutronic systems recommended the development of a new kinetic model allowing the calculation with any number of energy groups and also considering the transport for the angular variations. At this purpose, INL developed PHISICS (Parallel and Highly Innovative Simulation for INL Code System) and its coupling methodology with RELAP5-3D. The simulation activity described in this paper has been focused on the safety analysis of ALFRED reactor assuming the occurrence of two unprotected transient scenarios: unprotected loss of flow (ULOF) and unprotected transient overpower (UTOP). At this purpose, a thermal-hydraulic geometrical scheme of the whole reactor has been developed. The models and the outcomes of the calculations are described and discussed in the paper, highlighting the capability of the coupling approach to obtain results consistent with the ones available in the literature.
Direct condensation of steam in a water tank at sub-atmospheric pressures
Authors: Giambartolomei G , Pesetti A , Lazzeri R , Merello C , Sarkar B , Olcese M , Aquaro D
Published: September 2020

In the nuclear fusion reactor, ITER, the Loss of Coolant Accident (LOCA) in the Vacuum Vessel has to be managed with pressure suppression systems working at sub-atmospheric pressure. The operating conditions differ considerably from those experienced in the fission nuclear power plants such as BWR. The direct condensation at sub-atmospheric conditions is not sufficiently known, therefore, the effectiveness of systems operating at these particular conditions have to be investigated experimentally.

A research program is being carried out at the University of Pisa, funded by ITER, in order to study the steam direct condensation for nuclear fusion reactor conditions. For this purpose, an experimental test facility was designed and built and an extended experimental program was performed. Video cameras were used to visualize the steam condensation at different mass flow rates.

This paper deals with the elaboration of images of the steam jet flowing from a hole in the water. The steam condensation regimes depend on three governing parameters: downstream exit pressure, water temperature and steam mass flow rate per hole. Moreover, the condensation regimes are characterized by different shapes of steam jet.

The image analysis permitted to determine the heat transfer coefficient in the stable condensation regime at sub-atmospheric conditions. The results obtained are compared with those correspondent at steam condensation at atmospheric pressure, emphasizing the great importance of the downstream exit pressure and the subcooling on the steam condensation.
A novel approach for the numerical analysis of waste-to-energy plants
Authors: Arpino F , Buonanno G , Cortellessa G , Costa M. , Dell’Isola M , Massarotti N. , Zuena F
Published: September 2020

In this paper the authors present a simplified 0D-3D approach for modelling operating conditions of a waste-to-energy plant This innovative methodology combines a 0D lumped parameters model, able to describe the processes of solid and gaseous combustion and the heat transfer within the first radiant channel, with a detailed 3D CFD simulation of the thermo-fluid-dynamic field within the plant combustion chamber. Besides, results from the 0D model allow the definition of input data and boundary conditions for detailed 3D CFD simulation of the thermo-fluid-dynamic field within the plant combustion chamber. In this way, the T2S temperature can be determined using a more efficient and complete methodology. The developed numerical tool, does not employ correlations based on empiric observations or on experimental data regressions and, being phenomenological, is generally applicable to any waste-to-energy plant, and is here applied for the characterization of different operating conditions of an Italian WTE. The analysis allows the verification of the constraints imposed by the European legislation on the temperature of the combustion products and the identification of any issues related to the plant operation. Input parameters are determined from measurements and the obtained numerical results are validated against experiments showing a good agreement.
A thermo-economic based method for the design of process heat solar systems
Authors: Franco A , Bertola G
Published: September 2020

In this paper, the perspectives of production of thermal energy for industrial process heat from solar energy are considered. This represents a quite relevant topic for an overall containment of using fossil fuels with the objectives of reducing the impact of fossil fuel use. In particular, the paper outlines a thermo-economic design methodology taking into account the main variables problem (solar source, system architecture, design constraints, load type and distribution, design criteria and optimization criteria). The innovative element of the methodology is the consideration, among the various costs, of an economic penalty given to the operation of the auxiliary boiler. The results of the application in a particular case are shown in the final section of the paper, showing how it could be possible to increase the value of the solar share, up to 80% with respect to the conventional design method, that often limit this value at 60%.
Numerical and experimental study on metamaterials featuring acoustical and thermal properties
Authors: Levi Elisa , Neri Manuela , Pilotelli Mariagrazia , Alessio Piana Edoardo , Maria Lezzi Adriano
Published: September 2020

Metamaterials can be defined as materials which, for their peculiar composition or structure, exhibit characteristics that are not normally found in nature. “Multifunctional” metamaterials could be used to optimise different characteristics at the same time. In this paper the authors try to apply them for thermal and acoustic optimization of external building walls. Thermal optimization consists in obtaining a low transmittance, important in winter, and a low periodic thermal transmittance, important in summer. Acoustic optimization consists in obtaining high sound transmission loss, to respect the law prescriptions, and a good sound absorption coefficient, if possible. In this way should be possible enhance the comfort conditions in buildings and reduce the energy demand for winter heating and summer cooling. The proposed solution consists of several layers with different suitable characteristics: the sequence of the layers has been chosen with particular care. The thermal analysis has been performed by means of a self-developed code based on the ISO 13786 standard. The acoustic behaviour of the single layers has been determined following the procedure given by the ASTM E2611-09 standard using a four-microphone impedance tube and the transfer matrix method has been used for the complete assembly. This preliminary combined study showed encouraging results.
Performance of a Solar Assisted Heat Pump for Building Heating: Control Problems and Improvements
Authors: Tagliafico L. A. , Arteconi A. , Cavalletti A. , Marafioti C. , Marchitto A.
Published: September 2020

Palacus project is a solar assisted heat pump pilot plant in Genoa, Italy. The heat pump combined with solar hybrid photovoltaic thermal panels provides both electrical energy from the solar irradiation and hot water sent into the heat pump circuit. The photovoltaic field covers the energy need of the heat pump and it is even capable of producing extra electrical energy, stored in the national grid through a net-metering, looking for an energetically independent installation. The benefits coming from the net-metering, considered during the design stage, reduced dramatically due to a change in Italian laws concerning feed-in-premium. A brief report on the global facility performance during the past two years is proposed, proving the difficulties of the plant to reach its maximum design potential due to its complexity and problems related to the end users’ “acceptance”. Possible strategies to restore or increase the economic balance of the facility are discussed according to the new feed-in-premium criteria. Supervision and detection of any failure of the plant are performed by means of a large data acquisition system. New related regulation criteria, presented in this work, are compulsory to optimise the plant.
Insight in thermal and fluid-dynamic properties of ribbed ducts by means of a novel clustering method
Authors: Fustinoni Damiano , Vignati Federica , Gramazio Pasqualino , Vitali Luigi , Niro Alfonso
Published: September 2020

The analysis of experimental results on heat transfer by forced convection in diverse ribbed ducts showed that different geometries lead to comparable thermal and fluid-dynamic performances. Moreover, no evident layout has been observed in data, and therefore a statistical clustering analysis is performed to detect the rationale, if any, underlying experimental results. A novel, ad-hoc developed technique is used to disengage the clustering from the data scaling and to account for the measurement uncertainty, consisting of an agglomerative procedure, based on the definition of dynamically-changing bounding boxes, whose size depends on the Nusselt number and the pumping power. Additional informations, such as the the relevance of the diverse geometric parameters and the persistence of similarity among configurations over a range of operating conditions, can be retrieved by means of the developed technique. The described method is applied to a large dataset, obtained during an experimental campaign carried on at ThermALab of Politecnico di Milano, aimed at identifying the Nusselt number and the friction factor for diverse-rib configurations in a large-aspect ratio channel with low-Reynolds flows. The considerations originated from of the results of the clustering analysis suggest the existence of an underlying structure, pointing to a possible unique parameter, termed “generalized blockage”, which is possibly able to describe the global effect of the ribs geometry on forced convection.
Geometric uncertainty propagation in laminar flows solved by RBF-FD meshless technique
Authors: Zamolo R. , Parussini L.
Published: September 2020

The Non-Intrusive Polynomial Chaos method is employed to analyze incompressible and laminar fluid flows in presence of geometric uncertainties on the boundaries, which are described by stochastic variables with known probability distribution. Non-Intrusive methods allow the use of existing deterministic solvers, which are treated as black boxes. Therefore the quantification of the fluid flow uncertainties is based on a set of deterministic response evaluations. The required thermo-fluid dynamics solutions over the deterministic geometries are obtained through a Radial Basis Function-generated Finite Differences (RBF-FD) meshless method. The validation of the presented approach is carried out through analytical test cases (isothermal flow between non-parallel walls) with one geometric uncertainty. The applicability of the presented approach to practical problems is then presented through the prediction of geometric uncertainty effects on the non-isothermal flow over a heated backward-facing step.
Lumped parameter modelling of a thermoelectric cooler for high power electronics
Authors: Casano G , Piva S
Published: September 2020

A detailed analysis based on a lumped parameter model is presented of a cooling system for electronic equipments based on the combination of Peltier cells, air-cooling and liquid cold plate. A comprehensive model, specifically tailored for the cooling system under investigation, is introduced; the whole set of assumptions useful for the description of each element of the lumped parameter model, is described in depth. The model has been calibrated through an exhaustive comparison of numerical results versus experimental data, based on data gathered in experiments already published. Despite the large number of simplifying assumptions, the general good accordance between calculated and measured results demonstrate the reliability of the lumped parameter model, intended to be used for predicting the behaviour of the cooling system for currently untestable experimental conditions. Finally, the model is used as a useful design tool to investigate the cooling circuit under different operating conditions, in order to optimise the cooling solution here proposed.
Thermal properties of wood: measurements by transient plane source method in dry and wet conditions
Authors: Peron F. , Bison P. , De Bei M. , Romagnoni P.
Published: September 2020

Increasing use of wooden material in new constructions and retrofit activities push to a deeper comprehension of properties and specifically thermal properties of different wood species. On one side wooden products on the market are accompanied by few and generic information on the other side analysis of literature confirms a lack of experimental data on thermal conductivity of wood species grown in Italy. In this paper some species of softwood like spruce and larch, and hardwood, like elm, oak and ash are analysed and their thermal conductivities as a function of the equilibrium water content are evaluated by the use of a transient plane source. Results are in line with literature values and, in general, conductivity augments with water content increasing. The relationship between water content and conductivity exploited a linear behaviour for all species.
Saturation temperature effect on heat transfer coefficient during convective boiling in microfin tubes
Authors: Colombo L P M , Lucchini A , Phan T N , Molinaroli L , Niro A , Pozzoni M
Published: September 2020

The growing attention on environmental aspects puts severe constraints on HVAC technology, mainly involving the working fluids and energy efficiency. Both are related to the main limiting factor of HVAC system: the heat transfer process, which, frequently, involves boiling and condensation. To provide suitable tools for the HVAC system design, it is necessary to gather information on the heat transfer characteristics of the new refrigerants. Particular interest is focused on R1234ze(e), because it is one of the viable options to face the R134a phase out. Something similar can be repeated for the low temperature ORC systems using a refrigerant as working fluid. Using a specifically designed test rig, heat transfer coefficient and pressure drop measures were performed during flow boiling of R1234ze(e). The operating conditions were defined by four parameters: the evaporation temperature (5 °C, 35 °C and 45 °C), the mass flux (two values were considered: 160 kg/m2s and 220 kg/m2s), the average thermodynamic quality (which varies between 0.25 and 0.75) and the quality change (which was fixed to 0.2). The uncertainty affecting the pressure drop and the heat transfer coefficient resulted lower than 1% and 5% respectively. The results highlighted that the saturation temperature strongly affects the heat transfer coefficient and the pressure drop: as a consequence of the saturation temperature increase from 5 °C to 45 °C, it was observed up to 40% heat transfer coefficient increase and 90% pressure drop reduction.
Flow boiling of azeotropic and non-azeotropic mixtures. Effect of the glide temperature difference on the nucleate boiling contribution: assessment of methods
Authors: Mastrullo R , Mauro A W , Napoli G , Pelella F , Viscito L
Published: September 2020

Due to the increasing concern about the global warming caused by the use of conventional refrigerants, new HFC/HFO blends are currently proposed to replace high-GWP substances. Most of them, however, present a considerable temperature glide that may negatively affect the nucleate boiling contribution to the heat transfer during evaporation. In this paper, flow boiling data of the new non-azeotropic mixtures R452A and R448A (carrying a high temperature glide of almost 5 °C) and of the conventional quasi-azeotropic blend R404A are provided in a horizontal stainless-steel tube having an internal diameter of 6.0 mm. For all the investigated fluids, the operating conditions explore mass fluxes from 150 to 600 kg/m2s, saturation temperatures from 25 to 55 °C and imposed heat fluxes from 10 to 40 kW/m2, in the whole range of vapor qualities. The nucleative boiling contribution is then isolated from the overall heat transfer coefficient data at disposal and the effect of the heat flux is discussed for both types of blends. Finally, the experimental values and trends are compared to different nucleate boiling correlations taken from literature and conceived for pure fluids, by testing some correction factors explicitly developed for high temperature glide substances.
A new semi-empirical correlation for driving mass-flow rate calculation through ejectors for CO2 heat pumps. Comparison with predictions of other methods.
Authors: Boccardi G , Lillo G , Mastrullo R , Mauro A W , Pieve M , Trinchieri R
Published: September 2020

Carbon dioxide (CO2) is an interesting substitute of traditional HFCs in vapor compression systems, due to its environmentally friendly characteristics: zero ODP and extremely low GWP. Nevertheless, the use of CO2 heat pumps in residential heating and cooling applications actually is still limited, due to the different operating conditions of gas cooling, they can perform significantly worse than conventional.

The use of ejection systems for the fluid expansion in a refrigeration cycle can contribute to recovery part of the mechanical energy otherwise dissipated as friction, leading to significant benefits in terms of performance. The ejector sizing is a critical point for the balancing of components and the correct operation of the CO2 heat pump; in this regard, the availability of reliable methods for calculating the motive flow rate would be useful. In recent years, ENEA Laboratory DTE-PCU-SPCT of the Casaccia research center, along with the Industrial Engineering Department of Federico II University of Naples, carried on a project aimed at evaluating experimentally the effect of several ejectors geometries on the global performance of a CO2 heat pump working with a transcritical cycle.

This paper presents a new semi-empirical correlation for the ejector primary mass flow rate calculation, developed by the experimental data, based on the hypothesis of isentropic and choked flow. The correlation is then tested on other experimental data available in the literature for different ejectors. Finally, the predictions are compared to others semi-empirical correlations present in the literature.
Experimental and numerical activity on a prototype ejector chiller
Authors: Mahmoudian J , Mazzelli F , Milazzo A , Rocchetti A
Published: September 2020

Research activity on ejectors is ongoing at the University of Florence since the late nineties. The most important achievement is a 40 kW ejector chiller designed according to the “CRMC” criterion. The experimentally validated CFD simulations have given some hints about some possible improvements, i.e. refine the surface finish of the ejector, study the effect of heat transfer and improve the final part of the diffuser, which in its present shape does not produce a measurable compression. The prototype has been recently filled with low-GWP refrigerant R1233zd, as a drop-in replacement of previously used R245fa. Both fluids are “dry-expanding” and hence significantly easier to model in CFD simulations. Synthetic low-GWP refrigerants may be an option for ejector chillers, due to their ability to reach below-zero temperature and high volumetric refrigerant capacity. Some lessons learned with synthetic refrigerants can be transferred to the project of a steam ejector chiller, which remains one of our future targets. Herein we resume the principal findings gathered by means of experimental and numerical activity on our prototype and propose a few ideas for the future research.
First experimental results of the use of R1234yf and R1234ze(E) as drop-in substitutes for R134a in a water-to-water heat pump
Authors: Molinaroli L , Lucchini A , Colombo LPM , Bocchinfuso F
Published: September 2020

In the present paper, the first results of an experimental analysis carried out to assess the performance of a water-to-water heat pump in which R1234yf and R1234ze(E) are used as drop-in substitutes of R134a are shown. The heat pump is first tested with R134a to establish a baseline performance and, then, is tested under the same working conditions, i.e. under the same water temperatures at evaporator and condenser outlets, with the above-mentioned HFO refrigerants. The results show that the heating capacity and COP of R1234yf system are up to 9.8% and 6.1% respectively lower than those obtained with R134a. On the other side, the use of R1234ze(E) leads to a capacity reduction and a COP reduction respectively up to 23.1% and 2.5%. A second set of tests is then carried out varying the rotational frequency of the compressor shaft in order to set the heat pump heating capacity to the same value found with R134a. The experimental results demonstrate that increases up to 17% and 50% are respectively needed for R1234yf and R1234ze(E), but subsequent reductions of heat pump COP up to 7.38% and 18.11% arise.
Modelling carbon nano-tubes dynamical behaviour via nonlocal theory – free vibrations and dispersion relations
Authors: Muc A.
Published: September 2020

In the present paper the influence of non-local gradient formulations on the dynamical behaviour (free vibrations and dispersion relations) of carbon nanotubes analysed with the use of 2D shell theory is discussed. At the beginning the compact, consistent approach to the nonlocal (the Mindlin-Tiersten theory) description of 2D carbon nanoshells is shown. The presented results demonstrate the equivalence of free vibration analysis to the normal displacement mode (RBM) of carbon nanoshells. The possible extension of the presented formulations are also discussed.
Development of an Environmental Quality Index to Assess Physical Agents Pollution
Authors: Mancini S , Guida M , Graziuso G , Quartieri J , Guarnaccia C
Published: September 2020

Among the most common techniques and methodologies for the analysis of the exposure to polluting agents, the definition of environmental indexes represents a very useful tool to easily describe the quality of the environment. Based on experimental measurements, an approach using indicators quantitatively and qualitatively describes the ‘health status’ of the environments. For this reason, it is considered one of the most clear and efficient tools to support decisions and actions for the competent control authorities. In this paper the development of a general Physical Agents environmental Quality Index (PAQI) describing the potential impact related to the presence of all the different physical pollutants is discussed. The result is represented by a quantity that measures a weighted combination of sub-indices relating to each pollutant and described by means of an appropriate normalized mathematical function. The main idea is to provide an indicator able to describe, in a clear and concise way, the grade of physical pollution of the environment, suggesting in which areas it would be necessary to intervene or not, in order to improve the general environmental conditions.
Notes on New Physical & Hybrid Modelling Trends for Material Process Simulations
Authors: Horr Amir M
Published: September 2020

The more innovative production techniques for faster, cheaper and better-quality parts have encouraged more ambitious research works on numerical simulation of material & processes designs. A brief description of such ambitious work has been presented in this paper where some explanations of scientific and technical basis for some of latest physical & hybrid trends in material process simulations are concisely discussed. The topics of combining numerical, analytical and data-driven schemes along with evolving & dynamic mesh methods for simulation of dynamic material processes like casting, extrusion, Additive Manufacturing (AM) are also briskly described. Other trends like multi-scale and multi-resolution schemes for solidification (multi-phasing) and cooling applications are addressed, and fresh ideas of hybrid physical-data driven models (using Genetically Algorithm Symbolic Regression, GASR) and their applications are tersely presented. The effects of increasing computational power on hybrid multi-scale modelling and its implications for future of material modellings are also presented shortly. For the short paper herein, it has not been intended to publish the detailed results of new simulation technologies, rather it is focused on describing some new physical & hybrid trends for future of material process simulations.
Nonlocal beam model and FEM of free vibration for pristine and defective CNTs
Authors: Chwał M
Published: September 2020

The natural frequencies of defective single-walled carbon nanotubes are studied and compared with the values for pristine structures. In order to capture the size-dependent effects in carbon nanotubes, nonlocal stress gradient theory within a Euler-Bernoulli beam model is involved. The analytical computations are compared with finite element analysis of a structural model of carbon nanotubes. The numerical analysis of free vibrations is applied to predict the value of the nonlocal parameter. The eigenfrequencies obtained from finite element analysis are much lower compared with analytical computations of local (classical) beam model. For defective structures having small vacancy, a slight decrease in the eigenfrequencies is observed. All studied boundary conditions indicated the higher the nonlocal parameter is, the lower the natural frequencies are.
Modelling nuclear fuel assembly with thermal-hydraulic feedback and burnup using WIMS-PANTHER-Serpent
Authors: Li Jinfeng
Published: September 2020

State-of-the-art deterministic code sequence WIMS-PANTHER and Monte Carlo particle transport code Serpent are employed in this work for computationally modelling the UK EPR nuclear reactor core’s fuel assembly with and without thermal-hydraulic feedback, the results of which targets the government energy policymakers and wider academic community.
Free vibrations and flutter analysis of cylindrical shells
Authors: Augustyn M , Flis J , Muc A
Published: September 2020

The paper present the free vibration and the flutter of multi-layered cylindrical shells using the Rayleigh-Ritz method. The optimal design with constraints imposed on the eigenfrequencies is particularly useful in the selection of dynamic characteristics of structures. For composite cylindrical shells, the fiber orientation variations in individual layers results in an increase (decrease) the critical value of free vibrations. Optimal fibre orientations depends on the shell support and on the geometric parameters of a structure. In the case of the optimal laminate configuration finding, the optimization task cannot be solved using standard FEM software the application and genetic algorithms are required.
Proposal of a simplified Coulomb friction numerical model for the preliminary design of electrohydraulic servomechanisms
Authors: Dalla Vedova M D L , Salente E
Published: September 2020

Electrohydraulic servomechanisms (EHAs) are particularly interesting for aviation application, in fact tanks to the high power to weight ration are widely diffused in medium to large cargo and passengers planes or fighters. This work is focused on the proposal of a new dry friction numerical algorithm, based upon Coulomb’s approach, which can be integrated into simulation algorithms obtained by degrading the systems dynamic models (e.g. an over-damped second-order system reducible to a simpler first-order one). This approach, if correctly applied, significantly reduces the computational burden, without significant losses in simulation accuracy. The authors evaluated the approach proposed by a numerical test bench simulating the behaviour of an electrohydraulic linear actuator commonly used in primary flight controls.
Preparedness for the Emergencies in the City of Kyjov
Authors: Dzermansky M , Pekaj R
Published: September 2020

Population protection represents the fulfillment of tasks in the area of planning, organizing, and carrying out activities to prevent emergence, ensure emergency preparedness and crises and their solution. Among the priorities of individual cities is the protection of the population. For their infantry are planned elements of evacuation, loud warnings, hospital facilities, and more. Extraordinary events may occur unexpectedly, so it is necessary to be prepared for these situations and these purposes are established units of the integrated rescue system.
Analysis of noise annoyance complaints in the city of Milan, Italy
Authors: Zambon G. , Muchetti S.S. , Salvi D. , Angelini F. , Brambilla G. , Benocci R.
Published: September 2020

The paper describes the analysis of noise annoyance complaints submitted by citizens to the Municipality of Milan, Italy, from years 2000 to 2015. These complaints have been organized in a database and analysed according to: i) types of noise sources (technical facilities, music, transport infrastructures, etc.), ii) activities (retail and catering businesses, production, service sector, etc.) and iii) outcomes of the complaints inspection by local authorities. In addition, by means of a Geographic Information System (GIS) software, the spatial distribution of complaints has been determined according to the noise source type and activities, including also a geo-statistical representation by complaints density maps. The results show that, despite the dominant noise source in urban areas is mainly the road traffic, the other noises, such as those from industrial facilities, constructions and social activities (parties, fairs and open air markets, residential noise, etc.), are perceived as more disturbing. Since 2007, the number of noise complaints (about 100-150 complaints/year) is almost constant across the years. However, these complaints are expected to increase due to the growing and spreading of leisure activities, malls, exhibition centres and event venues, observed for the years 2014-2015.
Crowdsourcing Data for the Elaboration of Noise Maps: a Methodological Proposal
Authors: Graziuso G , Grimaldi M , Mancini S , Quartieri J , Guarnaccia C
Published: September 2020

In recent decades, the awareness that noise pollution caused by traffic, industry and recreational activities constitutes one of the main environmental problems is growing. In order to control the environmental noise, many regulations propose the creation of noise maps according to standard procedures that involves the data acquisition, analysis and elaboration. In this paper, crowdsourcing noise data collection is described. It involves volunteers that can record sound pressure levels thanks to specific applications on their mobile devices, such as the “NoiseCapture” app developed in France by CNRS and IFSTTAR, and upload the measurement, with their GPS location data, on a continuously updated map. This approach mainly contributes to citizens’ greater awareness about noise pollution in an urban area. Beside this mode of data acquisition, the paper focuses on the analysis of the acquired data with the kernel density estimation technique, implemented in a GIS environment. The results allows the elaboration of sound density maps, defined from the spatial and temporal point of view, that can support the appropriate mitigation actions.
Influence of rising the corners of a simply supported reinforced concrete slab on its reinforcement by numerical mehods
Authors: Vasiljev A V , Perekal’skiy O E , Vasiljeva N A , Larionov S G , Potapov Y B
Published: September 2020

The article presents a method for calculating a simply supported slab with a supple support contour using a numerical method in a computational software package. The support contour of a simply supported slab is formed by groups of two nodal finite elements, which allow modeling a linear supple bond in the vertical direction. They take into account the possibility of changes in the design scheme due to subsidence of the walls. The suppleness of the contour of prefabricated elements is 1 mm without taking into account the bends of the corners of a simply supported slab. The forces and reinforcement of a simply supported square slab were calculated according to the proposed methodology with a calculation where the joints of the contour are set to move in the vertical direction. As a result, the bending moments in the middle of the span increase, and the torques in the corners of the slab decrease. The reinforcement of the upper area of the slab is not required. The reinforcement of the lower area of the slab is increased by the amount of released reinforcement from the upper area of the slab.
Special polygon for investigation of seismic insulation properties of foundations
Authors: Lapin V A , Yerzhanov S Y , Aldakhov Y S
Published: September 2020

There is a special polygon to study the seismic insulating properties of buildings in Almaty. In 1989, stations of engineering seismometric service were installed on three constructed houses with the same supra-foundation part (9-storeyed large-panel houses), but with different foundations: conventional strip foundations with a system of cross strips, seismically isolating kinematic foundations and supports with PTFE gaskets. In the Republic of Kazakhstan, over 40 houses on kinematic foundations were built in Almaty. During the earthquake on August 16, 2014, instrumental records of the indicated earthquake were obtained. These instrumental records formed a very convenient for studying sample out of 10 accelerograms – they were obtained on the analogue house and two buildings with seismically isolating foundations. It has been established that the magnitudes of the acceleration at the level of the 9th floor in seismically isolated buildings are 47% less than the similar value in the building on a strip foundation. The maximum values of the spectral acceleration for seismically isolating buildings at the level of the 9th floor are 1.2 times less than the same value for FT, and 2.4 times for KF.
Optimization of the geometry of facades based on the results of studies of wind effects
Authors: Churin P S , Pomelov V Yu , Kovaleva A A
Published: September 2020

This article considers the possibility of reducing the wind load on building structures by optimizing their shape. The general algorithm for creating an architectural project using simulation engineering calculations is presented. The ANSYS Student software package analyzed the simplest methods of architectural shaping: bevels of ribs, rounding of edges, rounding of faces, vertical and horizontal articulations.
Curing kinetics in the activated cement-water system
Authors: Rubanov A V , Gorlenko N P , Sarkisov Yu S
Published: September 2020

The paper deals with the strength improvement in the cement-water system that generally leads to the improved performance of hydrated cement and concrete. After many years of experiments conducted by Russian and foreign experts, many ways to improve the strength of cement systems have been developed. The most efficient are various activation methods of either cement or water, which is then used as water of mixing for cements. This work studies the structure formation processes in the activated cement-water system, which are still less investigated. Cement is activated through its dispersion in a planetary mill, and water is activated by a constant magnetic field with 0.1 T flux density. It is found that the strength of the cement-water system increases by 38% in comparison with the untreated test samples.
Simulation Studies of Numerical Relationship of Sewage Energy Dissipation Chamber Efficiency
Authors: Stolbikhin I , Semenov A
Published: September 2020

The paper introduces a computer model to simulate design of an energy dissipation chamber (EDC). This model allows expressing the air flow rate through the system as a function of the incoming effluent rate. A method is developed to proceed with statistical analysis of simulation results. A set of plots of air flow rate is developed for effluent rates under different parameters of energy dissipation chamber. The approximating function and coefficients allowing obtaining the air consumption under certain conditions (geometrical parameters of the energy dissipation chamber and the effluent rate) are represented. The graphs are obtained in the form of three-dimensional surfaces reflecting a dependence of the ejected air flow rate on the incoming sewage liquid rate for at various values of the stand pipe embedment relative to the liquid level. The developed graphs show that the highest air flow rate is achieved at the maximum water flow rate and at the minimum embedment. Thus, the numerical dependences of the ejected air flow rates were obtained for the energy dissipation chamber as functions of the water flow rate. The embedment of the stand pipe at the level of the overflow wall and the zero inlet radius are shown to be the most effective parameters of energy dissipation chamber design.
Time necessary for microwave drying of mineral soils
Authors: Prokopowicz P , Pires P , Michałek A , Rybak A , Khairutdinov A M
Published: September 2020

Construction of large earthworks (cuts and embankments) brings the necessity of fast and reliable testing quality control procedures to be applied directly on the building sites. The paper presents a conventional, standardized method for determining soil moisture - consisting in drying a sample in a machine that circulates dry, hot air. This procedure is widely used and is considered to be very reliable and effective for any type of soil. Its main disadvantage is the time it takes to complete, as it takes a minimum of 24 hours to obtain the results of moisture content and consequently, to compute the compaction (density) indicator. An experiment was conducted, based on former Jastrzębska’s experiments and recommendations, consisting in drying soil samples in a microwave oven. The results were confronted and discussed with a special regard to necessary for microwave drying of mineral soils of different nature. Some recommendations were given in conclusions. As all the authors are still students, some remarks were juxtaposed concerning the importance of practical “experience-based” education within a frame of international exchange programs.
The peculiarities of power conservation and energy efficiency in power supply systems of industrial enterprises
Authors: Bebikhov Yu V , Semenov A S , Egorov A N , Glazun M A , Fedorov O V
Published: September 2020

The paper deals with the peculiarities connected with energy efficiency and power conservation measures in power supply systems of industrial enterprises. The purposes and objectives of the research conventionally divided into several areas: electric networks, electric drive, control and monitoring of energy consumption. The current state of energy and resource efficiency at industrial enterprises is described. The scientific literature of Russian and foreign authors working in this field is analyzed. The objects of research which are a mine and a processing plant for the extraction and processing of diamondiferous raw material are identified. The methods of mathematical modeling and instrumental monitoring are applied to analyze energy efficiency and power conservation. The region power supply system, automated (frequency-controlled) electric drive of processing units of mining enterprises, automated systems for monitoring and management of enterprises’ production processes are considered in the paper in details. The methods with a significant contribution to power conservation and energy efficiency of mining enterprises developed by the authors are presented. The conclusions on the prospects of future research in the field of energy efficiency and power conservation at mining enterprises are made.
The effectiveness of the Smart Office system
Authors: Salosin A , Gamayunova O , Mottaeva A
Published: September 2020

The capabilities of the Smart Office system allow you to control lighting, climate, safety in the building, as well as the work process as a whole. To assess the effectiveness of investments in the Smart Office system, the net present value, profitability index and payback period were calculated. The calculations showed that the implementation of the smart office system is an expensive, but justified in terms of energy efficiency and economy. As a result of the calculation, it was found that the cost of the system, taking into account the annual increase in utility tariffs by 7% and the increase in the discount rate by 9%, will pay off in 6 years, and the costs will begin to save money during the operation of the building.
The use of the Analytic Hierarchy Process in Determination of the Design Solution for Vertical Gardening
Authors: Ivanova N , Ganzha O , Podkovyrov I
Published: September 2020

The researches cover the methodological basis for formation of vertical gardening (landscaping) of building facades in the concept of landscape architecture, ecology of vertical gardening, green construction technologies and measures aimed at the improvement of the energy efficiency of buildings. The ‘Tree of Objectives’ is substantiated, which determines contemporary fields of development of green facades. For the first time, a methodology for choosing variants of the project design and technology solution of vertical gardening is proposed. In the work, multi-factor landscape ecological analysis is used; the analytical method of system analysis – the Analytic Hierarchy Process – is discussed. The author of the method is Thomas L. Saaty (USA), who represents the structure of a practical decision as a hierarchy, with further decomposition of the problem into more simple elements, and further, in the processing of the sequence of judgments of a decision maker on the basis of comparing elements to each other two at a time. In result, the intensity of interaction between elements in the hierarchy is described, and then, the judgments are expressed numerically. The method includes the procedures of synthesis of multiple judgments, of obtaining priority ranking of criteria, and finding alternative solutions. The proposed method for evaluation of a group of factors is universally applicable and can be easily used in practice, and also is the basis for preliminary selection of urban environment factors for creation of a comfort environment in the course of realization of landscape ecological properties of vertical gardening. The use of the system analysis method allows solving the analytical problem of choosing a design solution for vertical gardening system.