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1.
Investigating the influence of reflective materials on indoor thermal environment and solar reflectance in buildings
Jihui Yuan, Yasuhiro Shimazaki, Masaki Tajima, Shaoyu Sheng, Zhichao Jiao, Marko Bizjak, 2024, izvirni znanstveni članek

Opis: This in-depth study explores the intricate dynamics of reflective materials, emphasizing their impact on the indoor thermal environment and urban heat island (UHI) mitigation. Examining diffuse highly reflective (DHR), general reflective (GR), and retro-reflective (RR) materials on a simplified building model during summer days, the research utilizes outdoor experiments to analyze air and surface temperatures, as well as solar radiation. Prioritizing key metrics—mean radiant temperature (MRT), operative temperature (OT), and solar reflectance (ρ)—the study uncovers nuanced distinctions in DHR, GR, and RR materials. Solar reflectance calculations consistently show higher values for DHR and RR materials compared to GR material, highlighting reflectance's pivotal role in influencing surface temperatures and indoor thermal environment. When evaluating the impact of exterior wall materials on building temperatures, RR material with a 76% reflectance performs similarly to DHR material (82%). Notably, with a 6% lower reflectance in RR, the temperature contrast between external and internal walls is only about 1.5 °C at its maximum, underscoring RR's effectiveness as an outer wall material for UHI mitigation and building energy conservation, surpassing both DHR and GR materials.
Ključne besede: urban heat island, reflective materials, indoor thermal environment, solar reflectance, simplified building model
Objavljeno v DKUM: 23.08.2024; Ogledov: 98; Prenosov: 3
.pdf Celotno besedilo (4,82 MB)

2.
Exploring an infrastructure investment methodology to risk mitigation from rail hazardous materials shipments
Ali Vaezi, Manish Verma, 2021, izvirni znanstveni članek

Opis: Railroad is one of the primary modes to transport hazardous materials (hazmat) in North America. For instance, Canadian railroads carried around 50 million tons of hazmat in 2018. Given the inherent danger of trains carrying hazmat, this study aimed at exploring a novel way towards mitigation of the associated risk. This study sought to investigate whether proper rail track infrastructure investment can mitigate the risk from hazmat shipments. To this end, a methodology was developed and then applied to the Canadian railroad network. The proposed three-step methodology captured the differing perspectives of rail carriers and regulatory agencies, and entailed (1) ascertaining the risk-level of various yards and links in the given railroad network, (2) specifying potential candidates for infrastructure investment, and (3) finding the optimum set of investment decisions. The proposed methodology was then applied to the Canadian railroad network to demonstrate that significant risk-reduction can beachieved by adding alternative rail-links around the riskiest locations (i.e. the network hot-spots), and also to show that risk-reduction function is non-linear with non-monotonous behavior. The study showed the possibility of significant hazmat risk reduction through alternative rail-links that could take traffic away from the network hot-spots. The methodology and the resultsfrom the Canadian case can be used by railroad companies and policy makers to estimate the value of potentially risk-reducinginfrastructure investments.
Ključne besede: risk mitigation, railroad network, hazardous materials, infrastructure investment, optimization, transportation safety
Objavljeno v DKUM: 23.08.2024; Ogledov: 55; Prenosov: 3
.pdf Celotno besedilo (1,85 MB)
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3.
20th European Meeting on Supercritical Fluids : Book of Abstracts
2024

Opis: The 20th European Meeting on Supercritical Fluids (EMSF 2024) was hosted by the Faculty of Chemistry and Chemical Engineering of the University of Maribor from 26 May to 29 May 2024 in Maribor, Slovenia. The EMSF 2024 was a joint event of the International Society for the Advancement of Supercritical Fluids (ISASF) and the European Federation of Chemical Engineering (EFCE) Working Party on High Pressure Technology (WP HPT) Event No. 807. This symposium provided an excellent opportunity for engineers, chemists, physicists, food technologists, and biologists to meet and discuss new ideas, review ongoing challenges, present potential solutions, and identify future issues related to high pressure technologies and supercritical fluids. The aim of the meeting was to deepen connections between researchers, establish new contacts, and promote synergies and partnerships between researchers. The symposium presented the latest advances in high-pressure process technologies that can contribute to the further development of the field.
Ključne besede: supercritical fluids, fundamental data, novel materials, industrial applications, research and development
Objavljeno v DKUM: 24.07.2024; Ogledov: 150; Prenosov: 21
.pdf Celotno besedilo (12,44 MB)
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4.
Economic viability of alternative bedding material in broiler chicken farming
Jernej Prišenk, Maksimiljan Brus, 2022, izvirni znanstveni članek

Opis: The aim of this paper is to assess the economic viability of two different bedding materials used in broiler chicken farming processes. The materials considered are wood shavings and slice-dedusted straw. The slice-dedusted straw is considered an alternative type of bedding material produced by a company from Slovenia. While the technological and economic assessment of this type of bedding material has already been researched in the case of horse breeding, it is something new in the case of broiler chicken farming. Data collection is structured from two trials. Trial one (T1) is also known as daily observations, and trial two (T2) involves obtaining input data at the end of the fattening period. During T1, daily observations are focused on collecting data from technical characteristics, and in T2, the percentage of death proportions and average increments are observed, calculated, and considered as economic input data. The cost calculation model is used for the calculation of several different technical-economic indicators, which denote the influence of different bedding materials no economic production viability. Favorable economic results were found for slice-dedusted straw, which shows that this kind of alternative bedding material could be the better option.
Ključne besede: bedding materials, feasibility analysis, broiler chicken, cost calculation model
Objavljeno v DKUM: 02.07.2024; Ogledov: 94; Prenosov: 10
.pdf Celotno besedilo (6,19 MB)
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5.
Materials for HybridNeuro webinar titled "Validation of results: statistical models and MU identification accuracy"
Aleš Holobar, Nina Murks, 2024, zaključena znanstvena zbirka raziskovalnih podatkov

Opis: This dataset contains a collection of teaching materials that were used in the HybridNeuro project webinar titled "Validation of results: statistical models and MU identification accuracy". The webinar was presented by Aleš Holobar and covered the complexities of motor unit (MU) identification accuracy, regression analysis and Bayesian models. The primary aim of the webinar was to spark a robust discussion within the scientific community, particularly focusing on the application and implications of linear mixed models and Bayesian regression in the realm of MU identification. The teaching materials include Matlab and R source code for statistical analysis of the included data, as well as three examples of MU identification results in CSV format (from both synthetic and experimental HDEMG signals). The presentation slides in PDF format are also included. The dataset is approximately 9 MB in size.
Ključne besede: HybridNeuro, webinar, teaching materials, statistical models, regression analysis, motor unit identification, matlab, rstudio, statistics, surface high density electromyogram (HDEMG), tibialis anterior, dataset
Objavljeno v DKUM: 30.05.2024; Ogledov: 207; Prenosov: 15
.pdf Celotno besedilo (108,35 KB)
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6.
Thermo-mechanical behavior and strain rate sensitivity of 3D-printed polylactic acid (PLA) below glass transition temperature (Tg)
Vukašin Slavković, Blaž Hanželič, Vasja Plesec, Strahinja Milenković, Gregor Harih, 2024, izvirni znanstveni članek

Opis: This study investigated the thermomechanical behavior of 4D-printed polylactic acid (PLA), focusing on its response to varying temperatures and strain rates in a wide range below the glass transition temperature (Tg). The material was characterized using tension, compression, and dynamic mechanical thermal analysis (DMTA), confirming PLA’s strong dependency on strain rate and temperature. The glass transition temperature of 4D-printed PLA was determined to be 65 °C using a thermal analysis (DMTA). The elastic modulus changed from 1045.7 MPa in the glassy phase to 1.2 MPa in the rubber phase, showing the great shape memory potential of 4D-printed PLA. The filament tension tests revealed that the material’s yield stress strongly depended on the strain rate at room temperature, with values ranging from 56 MPa to 43 MPA as the strain rate decreased. Using a commercial FDM Ultimaker printer, cylindrical compression samples were 3D-printed and then characterized under thermo-mechanical conditions. Thermo-mechanical compression tests were conducted at strain rates ranging from 0.0001 s−1 to 0.1 s−1 and at temperatures below the glass transition temperature (Tg) at 25, 37, and 50 °C. The conducted experimental tests showed that the material had distinct yield stress, strain softening, and strain hardening at very large deformations. Clear strain rate dependence was observed, particularly at quasi-static rates, with the temperature and strain rate significantly influencing PLA’s mechanical properties, including yield stress. Yield stress values varied from 110 MPa at room temperature with a strain rate of 0.1 s−1 to 42 MPa at 50 °C with a strain rate of 0.0001 s−1. This study also included thermo-mechanical adiabatic tests, which revealed that higher strain rates of 0.01 s−1 and 0.1 s−1 led to self-heating due to non-dissipated generated heat. This internal heating caused additional softening at higher strain rates and lower stress values. Thermal imaging revealed temperature increases of 15 °C and 18 °C for strain rates of 0.01 s−1 and 0.1 s−1, respectively.
Ključne besede: smart materials, shape memory polymer, 3D printing, 4D printing, thermo-mechanical experiments
Objavljeno v DKUM: 29.05.2024; Ogledov: 229; Prenosov: 13
.pdf Celotno besedilo (5,88 MB)
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7.
Mechanical behaviour of photopolymer cell-size graded triply periodic minimal surface structures at different deformation rates
Yunus Emre Yilmaz, Nejc Novak, Oraib Al-Ketan, Hacer Irem Erten, Ulas Yaman, Anja Mauko, Matej Borovinšek, Miran Ulbin, Matej Vesenjak, Zoran Ren, 2024, izvirni znanstveni članek

Opis: This study investigates how varying cell size affects the mechanical behaviour of photopolymer Triply Periodic Minimal Surfaces (TPMS) under different deformation rates. Diamond, Gyroid, and Primitive TPMS structures with spatially graded cell sizes were tested. Quasi-static experiments measured boundary forces, representing material behaviour, inertia, and deformation mechanisms. Separate studies explored the base material’s behaviour and its response to strain rate, revealing a strength increase with rising strain rate. Ten compression tests identified a critical strain rate of 0.7 s−1 for “Grey Pro” material, indicating a shift in failure susceptibility. X-ray tomography, camera recording, and image correlation techniques observed cell connectivity and non-uniform deformation in TPMS structures. Regions exceeding the critical rate fractured earlier. In Primitive structures, stiffness differences caused collapse after densification of smaller cells at lower rates. The study found increasing collapse initiation stress, plateau stress, densification strain, and specific energy absorption with higher deformation rates below the critical rate for all TPMS structures. However, cell-size graded Primitive structures showed a significant reduction in plateau and specific energy absorption at a 500 mm/min rate.
Ključne besede: cellular materials, triply periodical minimal surface, photopolymer, mechanical properties, strain rate, experimental compressive testing, computer simulations
Objavljeno v DKUM: 22.05.2024; Ogledov: 198; Prenosov: 14
.pdf Celotno besedilo (9,33 MB)
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8.
9.
Advance analysis of the obtained recycled materials from used disposable surgical masks
Alen Erjavec, Julija Volmajer Valh, Silvo Hribernik, Tjaša Kraševac Glaser, Lidija Fras Zemljič, Tomaž Vuherer, Branko Neral, Mihael Brunčko, 2024, izvirni znanstveni članek

Opis: The production of personal protective equipment (PPE) has increased dramatically in recent years, not only because of the pandemic, but also because of stricter legislation in the field of Employee Protection. The increasing use of PPE, including disposable surgical masks (DSMs), is putting additional pressure on waste collectors. For this reason, it is necessary to find high-quality solutions for this type of waste. Mechanical recycling is still the most common type of recycling, but the recyclates are often classified as low-grade materials. For this reason, a detailed analysis of the recyclates is necessary. These data will help us to improve the properties and find the right end application that will increase the value of the materials. This work represents an extended analysis of the recyclates obtained from DSMs, manufactured from different polymers. Using surface and morphology tests, we have gained insights into the distribution of different polymers in polymer blends and their effects on mechanical and surface properties. It was found that the addition of ear loop material to the PP melt makes the material tougher. In the polymer blends obtained, PP and PA 6 form the surface (affects surface properties), while PU and PET are distributed mainly inside the injection-molded samples.
Ključne besede: mechanical recycling, disposable surgical mask, morphology, surface properties, mechanical properties, nonwoven materials, PPE
Objavljeno v DKUM: 09.04.2024; Ogledov: 214; Prenosov: 11
.pdf Celotno besedilo (8,08 MB)
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10.
Cellulose–chitosan functional biocomposites
Simona Strnad, Lidija Fras Zemljič, 2023, pregledni znanstveni članek

Opis: Here, we present a detailed review of recent research and achievements in the field of combining two extremely important polysaccharides; namely, cellulose and chitosan. The most important properties of the two polysaccharides are outlined, giving rise to the interest in their combination. We present various structures and forms of composite materials that have been developed recently. Thus, aerogels, hydrogels, films, foams, membranes, fibres, and nanofibres are discussed, alongside the main techniques for their fabrication, such as coextrusion, co-casting, electrospinning, coating, and adsorption. It is shown that the combination of bacterial cellulose with chitosan has recently gained increasing attention. This is particularly attractive, because both are representative of a biopolymer that is biodegradable and friendly to humans and the environment. The rising standard of living and growing environmental awareness are the driving forces for the development of these materials. In this review, we have shown that the field of combining these two extraordinary polysaccharides is an inexhaustible source of ideas and opportunities for the development of advanced functional materials.
Ključne besede: biocomposites, functional materials, cellulose–chitosan, fibers, films, hydrogels, nanofibers
Objavljeno v DKUM: 19.02.2024; Ogledov: 284; Prenosov: 23
.pdf Celotno besedilo (6,52 MB)
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