An emergency caused by the COVID-19 pandemic affected the rethinking of existing healthcare systems. The increased need for hospital beds appeared short after the outbreak of the pandemic and the ...solution was to adapt the existing buildings, primarily public ones. Among all, sports buildings, i.e. sports halls were successfully used around the globe for conversion into hospitals. Topic of the paper was to investigate whether sports halls in Serbia, which were also used as temporary hospitals, are suitable for conversion in terms of energy consumption needed for achieving thermal comfort. Two case studies were analysed. The energy simulations were done using the DesingBuilder software. The results of thermal comfort summary and energy consumption led to the conclusion that this building type in Serbia could be successfully used for hospital purposes. Although the multiple increase in energy consumption was noted during the heating period, the results were within the limits required by both national and international standards.
The Archimedean spiral coil made of a transversely corrugated pipe represents the radiant heat absorber of a parabolic dish solar concentrator. The main advantage of the considered design is the ...coupling of two passive methods for heat transfer enhancement: coiling the flow channel and changing the surface roughness. The aim of this numerical study is to assess the capability of RANS models of different complexity (realizable k-?, SST k-?, and RSM linear pressure-strain) to adequately represent the heat transfer phenomena in the considered complex flow geometry for wide ranges of Reynolds and Prandtl numbers. The obtained results indicate that the realizable k-? model with enhanced wall treatment is inadequate to simulate the heat transfer for all flow conditions, while both SST and RSM slightly overestimate experimental data in the turbulent region and are able to predict laminarisation at low Reynolds numbers. The SST model predictions are more accurate in the transitional and at the beginning of the turbulent region, irrespective of the curvature ratio. The RSM predictions are generally more accurate in the turbulent region. Numerically obtained circumferential distributions of local Nusselt number reveal that considered turbulence models are unable to completely anticipate the interactions between the complex flow in the basic section of the pipe and the vortex flow within the corrugations.
Polypropylene is a widely used linear hydrocarbon polymer with diverse applications due to its exceptional physicochemical characteristics and minimal changes during the recycling process. Numerous ...studies have focused on factors influencing the mechanical properties of polypropylene and its application in composites. However, despite their significance in the agricultural industry, there is limited research on polypropylene baling twines. This study analyses the behaviour of polypropylene baling twine under tensile loading, exploring the influence of fibre friction and twisting angle on the material’s tensile strength. Experimental investigation indicated that tensile strength increases with twisting angle, but only until the angle reaches a critical value. Further increase in the twist angle led to a decrease in tensile strength. The increase in tensile strength is attributed to the rise in the coefficient of friction between fibres in the twine. An experimental approach was employed to evaluate the mechanical characteristics of the twine, including the effect of prestressing by twisting. Understanding these characteristics is crucial for enhancing the quality of polypropylene baling twines and optimising their application in the agricultural industry.
Analytical Estimation of Map Readability Harrie, Lars; Stigmar, Hanna; Djordjevic, Milan
ISPRS international journal of geo-information,
06/2015, Letnik:
4, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Readability is a major issue with all maps. In this study, we evaluated whether we can predict map readability using analytical measures, both single measures and composites of measures. A user test ...was conducted regarding the perceived readability of a number of test map samples. Evaluations were then performed to determine how well single measures and composites of measures could describe the map readability. The evaluation of single measures showed that the amount of information was most important, followed by the spatial distribution of information. The measures of object complexity and graphical resolution were not useful for explaining the map readability of our test data. The evaluations of composites of measures included three methods: threshold evaluation, multiple linear regression and support vector machine. We found that the use of composites of measures was better for describing map readability than single measures, but we could not identify any major differences in the results of the three composite methods. The results of this study can be used to recommend readability measures for triggering and controlling the map generalization process of online maps.
There is an increasing interest to study the interactions between atmospheric electrical parameters and living organisms at multiple scales. So far, relatively few studies have been published that ...focus on possible biological effects of atmospheric electric and magnetic fields. To foster future work in this area of multidisciplinary research, here we present a glossary of relevant terms. Its main purpose is to facilitate the process of learning and communication among the different scientific disciplines working on this topic. While some definitions come from existing sources, other concepts have been re-defined to better reflect the existing and emerging scientific needs of this multidisciplinary and transdisciplinary area of research.
A polygeneration system is an energy system capable of providing multiple
utility outputs to meet local demands by application of process integration.
This paper addresses the problem of pinpointing ...the optimal polygeneration
energy supply system for the local energy demands of a livestock farm in
terms of optimal system configuration and optimal system capacity. The
optimization problem is presented and solved for a case study of a pig farm
in the paper. Energy demands of the farm, as well as the super-structure of
the polygeneration system were modelled using TRNSYS software. Based on the
locally available resources, the following polygeneration modules were chosen
for the case study analysis: a biogas fired internal combustion engine
co-generation module, a gas boiler, a chiller, a ground water source heat
pump, solar thermal collectors, photovoltaic collectors, and heat and cold
storage. Capacities of the polygeneration modules were used as optimization
variables for the TRNSYS-GenOpt optimization, whereas net present value,
system primary energy consumption, and CO2 emissions were used as goal
functions for optimization. A hybrid system composed of biogas fired internal
combustion engine based co-generation system, adsorption chiller solar
thermal and photovoltaic collectors, and heat storage is found to be the best
option. Optimal heating capacity of the biogas co-generation and adsorption
units was found equal to the design loads, whereas the optimal surface of the
solar thermal array is equal to the south office roof area, and the optimal
surface of the PV array corresponds to the south facing animal housing
building rooftop area.
A polygeneration system is an energy system capable of providing multiple
energy outputs to meet local demands, by application of high process
integration. In this paper, optimal configuration and ...capacity of a
polygeneration system for an indoor swimming pool building is determined by
application of a method based on TRNSYS simulation and GenOpt optimization
software. Based on the applicability, a superstructure of the polygeneration
system is integrated, consisting of the following polygeneration modules: an
internal combustion engine cogeneration module, a vapor compression chiller,
and adsorption chiller, a ground source heat pump, flat plate solar thermal
collectors, photovoltaic collectors, and heat storage. Annual behavior of
energy loads of the public swimming pool building during a typical
meteorological year and the polygeneration system are modeled and simulated
using TRNSYS software, whereas techno-economic optimization is performed by
GenOpt optimization. The results indicated the optimal con-figuration of the
polygeneration system for the modelled energy demands, as well as the optimal
capacity of the polygeneration modules, thus defining the optimal capacity of
the polygeneration system for the energy demands of the public swimming pool
building.
This paper presents an experimental and numerical study into the influence of elevated temperatures on mechanical properties of the heat treated high quality hot work tool steel H11. This steel ...belongs to a group of alloyed steels with extraordinary mechanical properties. The aim of this study was to determine the highest temperature at which these properties are still maintained. The experimental investigation focused on the tensile testing of specimens at seven different temperatures, including the room temperature. The highest testing temperature was 700 °C. The heat treatment of plates (specimens) consisted of quenching and tempering. Although the strain hardening of this type of materials is small, the strain hardening curves were calculated to show if there was a possibility for the material to increase its strength due to exploitation loads. Also, a numerical analysis of the tensile test by using the finite element method was done in order to define an appropriate model for numerical testing. The obtained results are then compared with the experimental results.
Isothermal pressure drop experiments were carried out for the steady Newtonian fluid flow in Archimedean spiral tube with transverse corrugations. Pressure drop correlations and stability criteria ...for distinguishing the flow regimes have been obtained in a continuous Reynolds number range from 150 to 15 000. The characterizing geometrical groups which take into account all the geometrical parameters of Archimedean spiral and corrugated pipe has been acquired. Before performing experiments over the Archimedean spiral, the corrugated straight pipe having high relative roughness e/d = 0.129 of approximately sinusoidal type was tested in order to obtain correlations for the Darcy friction factor. Insight into the magnitude of pressure loss in the proposed geometry of spiral solar receiver for different flow rates is important because of its effect upon the efficiency of the receiver. Although flow in spiral and corrugated geometries has the advantages of compactness and high heat transfer rates, the disadvantage of greater pressure drops makes hydrodynamic studies relevant. Projekat Ministarstva nauke Republike Srbije, br. III 42006 i br. TR 33015
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