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1923. Percutaneous transluminal angioplasty of an aortic recoarctation : case reportDušan Pavčnik, Andrej Robida, 1987, izvirni znanstveni članek Povzetek: Two cases of successful dilatation of recoarctation of the aorta due to a subclavien turndown operation are reported. In both cases Grüntzig technique was used. The first patient, aged 10 months, had the gradient rediced from 40 mm Hg to 10 mm Hg. The second, aged 1 year, had the gradient reduced from 80 mm Hg to 30 mm Hg. In the second patient right femoral pulse disapeared after procedure and surgery (thrombarteriectomy) was performed.
Objavljeno v DiRROS: 15.09.2023; Ogledov: 293; Prenosov: 67
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1924. Impacts of casting scales and harsh conditions on the thermal, acoustic, and mechanical properties of indoor acoustic panels made with fiber-reinforced alkali-activated slag foam concretesMohammad Mastali, Paivo Kinnunen, Marjaana Karhu, Zahra Abdollahnejad, Lidija Korat, Vilma Ducman, Ahmad Alzaza, Mirja Illikainen, 2019, izvirni znanstveni članek Povzetek: This paper presents experimental results regarding the efficiency of using acoustic panels made with fiber-reinforced alkali-activated slag foam concrete containing lightweight recycled aggregates produced by using Petrit-T (tunnel kiln slag). In the first stage, 72 acoustic panels with dimension 500 % 500 % 35 mm were cast and prepared. The mechanical properties of the panels were then assessed in terms of their compressive and flexural strengths. Moreover, the durability properties of acoustic panels were studied using harsh conditions (freeze/thaw and carbonation tests). The efficiency of the lightweight panels was also assessed in terms of thermal properties. In the second stage, 50 acoustic panels were used to cover the floor area in a reverberation room. The acoustic absorption in diffuse field conditions was measured, and the interrupted random noise source method was used to record the sound pressure decay rate over time. Moreover, the acoustic properties of the panels were separately assessed by impedance tubes and airflow resistivity measurements. The recorded results from these two sound absorption evaluations were compared. Additionally, a comparative study was presented on the results of impedance tube measurements to compare the influence of casting volumes (large and small scales) on the sound absorption of the acoustic panels. In the last stage, a comparative study was implemented to clarify the effects of harsh conditions on the sound absorption of the acoustic panels. The results showed that casting scale had great impacts on the mechanical and physical properties. Additionally, it was revealed that harsh conditions improved the sound properties of acoustic panels due to their effects on the porous structure of materials.
Ključne besede: alkali activation, slag, acoustic panels
Objavljeno v DiRROS: 15.09.2023; Ogledov: 298; Prenosov: 164
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1925. Algorithm instance footprint : separating easily solvable and challenging problem instancesAna Nikolikj, Sašo Džeroski, Mario Andrés Muñoz, Carola Doerr, Peter Korošec, Tome Eftimov, 2023, objavljeni znanstveni prispevek na konferenci Ključne besede: black-box optimization, algorithms, problem instances, machine learning
Objavljeno v DiRROS: 15.09.2023; Ogledov: 303; Prenosov: 200
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1926. Assessing the generalizability of a performance predictive modelAna Nikolikj, Gjorgjina Cenikj, Gordana Ispirova, Diederick Vermetten, Ryan Dieter Lang, Andries Petrus Engelbrecht, Carola Doerr, Peter Korošec, Tome Eftimov, 2023, objavljeni znanstveni prispevek na konferenci Ključne besede: algorithms, predictive models, machine learning
Objavljeno v DiRROS: 15.09.2023; Ogledov: 319; Prenosov: 210
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1927. Novel thermal insulation with gas-filled cavities - assessment of thermal performance of different designs based on numerical simulations of heat transferMiha Jukić, Sabina Jordan, Danijel Lisičić, 2019, izvirni znanstveni članek Povzetek: Not only is the energy efficiency of buildings nowadays becoming more and more important; the legislative requirements, the people’s awareness of the environmental questions and their thermal comfort expectations are also on a much higher level. All of these issues can be addressed by making the building envelope more thermally resistant. However, with the traditional thermal insulation materials the thickness of thermal insulation layers is already at the viable limits. Therefore, the development of new, more efficient thermal insulation products with a higher thermal resistance is highly promoted. Preliminary research results can be applied to models to develop and confirm the conceptual designs of such new materials. In this paper, an analysis of thermal performance is presented for a novel thermal insulation consisting of graphite polystyrene (GPS) matrix with cavities filled with an insulative gas, and a protective sheath to prevent it from leaking. Bearing in mind the suitability for later production, different configurations of the assembly were considered, regarding the matrix geometry, the type of the gas filling, and the surface emissivity of the cavities. A range of numerical simulations of heat transfer was conducted to determine the efficiency of different designs in reducing the conductive, the convective, and the radiative heat transfer. Advantages, limitations and some detailed parameters of the proposed design concepts were determined, which were then used for optimisation. The analysis of the results indicates that the equivalent thermal conductance of a GPS panel can be significantly reduced by the introduction of gas-filled cavities. The reduction is highly dependent on the type of the gas filling (thermal conductivity, viscosity, specific heat, etc.), the size of the cavities, and the cavity surface emissivity.
Ključne besede: gas-filled cavities, graphite polystyrene, numerical simulation, thermal insulation
Objavljeno v DiRROS: 15.09.2023; Ogledov: 280; Prenosov: 128
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1928. Effects of specific parameters on simulations of energy use and air temperatures in offices equipped with radiant heating/cooling panelsSabina Jordan, Jože Hafner, Martina Zbašnik-Senegačnik, Andraž Legat, 2019, izvirni znanstveni članek Povzetek: When creating a simulation model to assess the performance of buildings, there is usually a lack of feedback information. Only in the case of measurements of a real building is a direct comparison of the measured values and simulated results possible. Parameter data related to users’ behavior or other events can also be obtained. Their evaluated frequency, magnitude and duration, along with boundary conditions, are crucial for the results. It is clear that none of them can be predicted very accurately. Most of them, however, are needed for computer modeling. In this paper we analyzed the well-defined TRNSYS simulation model of offices equipped with radiant ceiling panels for heating and cooling. The model was based on real case offices and was validated based on measurements for 1 year. The analysis included simulations in order to define what effect the parameters related mainly to users have on the energy use and the indoor air temperatures. The study confirmed that specific human activities influence the annual energy use to a relatively small degree and that their effects often counteract. It also confirmed the even more important fact that although small, these activities can influence the thermal comfort of users. It is believed that despite the fact that this research was based on an analysis of offices equipped with radiant ceiling panels, most of the results could be applied generally.
Ključne besede: measurements, modeling, simulation, validation, analysis, energy use, temperature
Objavljeno v DiRROS: 15.09.2023; Ogledov: 328; Prenosov: 153
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