1. Integrated optimization framework for a biomass supply network and steam Rankine cycleMonika Dokl, Zdravko Kravanja, Lidija Čuček, 2024, izvirni znanstveni članek Opis: The optimization of biomass supply chains is becoming increasingly important, especially for low-density biomass feedstocks that have limited market value and require efficient handling and logistics. This study addresses this issue by proposing an integrated approach to optimize biomass supply chain networks for energy production with the steam Rankine cycle. The approach takes into account the inherent variability of feedstock availability and energy market values, to ensure adaptability to fluctuating conditions. The biomass supply network is formulated as a mixed-integer nonlinear programming problem, where the optimization objective is to maximize the economic viability of the system. The optimal configuration of the supply network includes the selection of biomass supply zones and storage facilities, the transportation links, and the optimization of the process variables within the conversion plants, taking into account the variable heat demand. The optimization approach is applied to a hypothetical case study of a relatively small region in Slovenia. The results show the economic viability of biomass utilization with a net present value of almost 300 MEUR, generating about 4 MW of electricity and 65 MW of heat. The uncertainties of the biomass supply, the fluctuations in product prices and the spatial scope of the case study are evaluated in addition. This analysis highlights and discusses the impact of these factors on the economic performance of the biomass supply chain network. Ključne besede: copper(II) coordination compounds, methylamines, crystal structure, magnetic properties, thermogravimetric analysis Objavljeno v DKUM: 31.01.2025; Ogledov: 0; Prenosov: 1
Celotno besedilo (1,15 MB) |
2. The correlation between demographic development and land-use changes in SloveniaUroš Horvat, Igor Žiberna, 2020, izvirni znanstveni članek Opis: The paper focuses on determining the degree of correlation between land-use changes and demographic development in Slovenia. The authors conclude that there is still insufficient evidence in the literature for a correlation between these two processes, because quantitative studies addressing these links are very rare and mostly cover small and specific areas. In the case of Slovenia, Spearman’s correlation coefficients are quite low, which confirms that land-use change processes are complex and not dependent solely on individual demographic and socioeconomic factors. Despite the low correlation coefficients, our findings indicate that changes in land use are significantly influenced by changes in age structure and population growth. In areas with population growth the share of arable land is shrinking, whereas in areas with depopulation and a rising aging index the share of partially overgrown land is growing. In the following analysis, the authors focus their analysis on a case study of the Mura and Central Slovenia statistical regions, which lie on opposite poles with regard to development, and thus show differing trends in land-use changes. Ključne besede: land use, geography, agricultural land, arable land, afforestation, demography, age structure, Slovenia Objavljeno v DKUM: 23.01.2025; Ogledov: 0; Prenosov: 3
Celotno besedilo (4,34 MB) Gradivo ima več datotek! Več... |
3. |
4. Flower-like superhydrophobic surfaces fabricated on stainless steel as a barrier against corrosion in simulated acid rainRegina Fuchs-Godec, 2022, izvirni znanstveni članek Opis: Functionalisation of the metal surface of low-carbon ferritic stainless steel (from hydrophilic to hydrophobic properties) was achieved by flower-like hierarchical structures on a steel substrate prepared by a low-cost immersion method. The flower-like structured hydrophobic layers on the steel substrate were obtained by immersing the samples in an ethanolic solution of stearic acid with the addition of various concentrations of expired vitamin E ((+)α-tocopherol). The stability and corrosion-inhibiting effect of the hierarchically structured (such as natural cornflower) hydrophobic layers were studied systematically during short and long immersion tests, 120 h (five days) in an acidic environment (pH = 3) using potentiodynamic measurements, electrochemical impedance spectroscopy and chronopotentiometry. The surfaces of the samples, their wettability, surface morphology and chemical composition were characterised by contact angle measurements, SEM, ATR-FTIR and EDAX. After 120 h of immersion, the inhibition efficiency of the flower-like structured hydrophobic layers on the steel substrate in the selected corrosion medium remained above 99%, and the hierarchical structure (flower-like structure) was also retained on the surface. Ključne besede: acid rain, corrosion, flower-like structure, inhibition, stainless steel Objavljeno v DKUM: 05.12.2024; Ogledov: 0; Prenosov: 2
Celotno besedilo (4,56 MB) Gradivo ima več datotek! Več... |
5. Fluid flow simulation with an ▫$ℋ^2$▫ -accelerated boundary-domain integral methodJan Tibaut, Jure Ravnik, M Schanz, 2024, izvirni znanstveni članek Opis: The development of new numerical methods for fluid flow simulations is challenging but such tools may help to understand flow problems better. Here, the Boundary-Domain Integral Method is applied to simulate laminar fluid flow governed by a dimensionless velocity–vorticity formulation of the Navier–Stokes equation. The Reynolds number is chosen in all examples small enough to ensure laminar flow conditions. The false transient approach is utilized to improve stability. As all boundary element methods, the Boundary-Domain Integral Method has a quadratic complexity. Here, the ℋ2 -methodology is applied to obtain an almost linear complexity. This acceleration technique is not only applied to the boundary only part but more important to the domain related part of the formulation. The application of the ℋ2 -methodology does not allow to use the rigid body method to determine the singular integrals and the integral free term as done until now. It is shown how to apply the technique of Guigiani and Gigante to handle the strongly singular integrals in this application. Further, a parametric study shows the influence of the introduced approximation parameters. For this purpose the example of a lid driven cavity is utilized. The second example demonstrates the performance of the proposed method by simulating the Hagen–Poiseuille flow in a pipe. The third example considers the flow around a rigid cylinder to show the behavior of the method for an unstructured grid. All examples show that the proposed method results in an almost linear complexity as the mathematical analysis promisses. Ključne besede: boundary-domain integral method, velocity–vorticity, adaptive cross approximation, modified helmholtz equation, Yukawa potential, fast multipole method, ℋ-structure Objavljeno v DKUM: 28.11.2024; Ogledov: 0; Prenosov: 7
Celotno besedilo (3,06 MB) Gradivo ima več datotek! Več... |
6. A study on the compressive behavior of additively manufactured AlSi10Mg lattice structuresDavid Liović, Sanjin Krščanski, Marina Franulović, Dražan Kozak, Goran Turkalj, Emanuele Vaglio, Marco Sortino, Giovanni Totis, Federico Scalzo, Nenad Gubeljak, 2024, izvirni znanstveni članek Opis: The mechanical behavior of the metallic components fabricated by additive manufacturing (AM) technologies can be influenced by adjustments in their microstructure or by using specially engineered geometries. Manipulating the topological features of the component, such as incorporating unit cells, enables the production of lighter metamaterials, such as lattice structures. This study investigates the mechanical behavior of lattice structures created from AlSi10Mg, which were produced using the laser beam powder bed fusion (LB-PBF) process. Specifically, their behavior under pure compressive loading has been numerically and experimentally investigated using ten different configurations. Experimental methods and finite element analysis (FEA) were used to investigate the behavior of body-centered cubic (BCC) lattice structures, specifically examining the effects of tapering the struts by varying their diameters at the endpoints (�end ) and midpoints (�mid ), as well as altering the height of the joint nodes (h). The unit cells were designed with varying parameters in such a way that �end is changed at three levels, while �mid and h are changed at two levels. Significant differences in Young’s modulus, yield strength, and ultimate compressive strength between the various specimen configurations were observed both experimentally and numerically. The FEA underestimated the Young’s modulus corresponding to the configurations with thinner struts in comparison to the higher values found experimentally. Conversely, the FEA overestimated the Young’s modulus of those configurations with larger strut diameters with respect to the experimentally determined values. Additionally, the proposed FE method consistently underestimated the yield strength relative to the experimental values, with notable discrepancies in specific configurations. Ključne besede: lattice structure, BCC, compressive behavior, additive manufacturing, AlSi10Mg Objavljeno v DKUM: 25.11.2024; Ogledov: 0; Prenosov: 2
Celotno besedilo (15,75 MB) Gradivo ima več datotek! Več... |
7. Socio-demographic and health factors drive the epidemic progression and should guide vaccination strategies for best COVID-19 containmentRene Markovič, Marko Šterk, Marko Marhl, Matjaž Perc, Marko Gosak, 2021, izvirni znanstveni članek Opis: We propose and study an epidemiological model on a social network that takes into account heterogeneity of the population and different vaccination strategies. In particular, we study how the COVID-19 epidemics evolves and how it is contained by different vaccination scenarios by taking into account data showing that older people, as well as individuals with comorbidities and poor metabolic health, and people coming from economically depressed areas with lower quality of life in general, are more likely to develop severe COVID-19 symptoms, and quicker loss of immunity and are therefore more prone to reinfection. Our results reveal that the structure and the spatial arrangement of subpopulations are important epidemiological determinants. In a healthier society the disease spreads more rapidly but the consequences are less disastrous as in a society with more prevalent chronic comorbidities. If individuals with poor health are segregated within one community, the epidemic outcome is less favorable. Moreover, we show that, contrary to currently widely adopted vaccination policies, prioritizing elderly and other higher-risk groups is beneficial only if the supply of vaccine is high. If, however, the vaccination availability is limited, and if the demographic distribution across the social network is homogeneous, better epidemic outcomes are achieved if healthy people are vaccinated first. Only when higher-risk groups are segregated, like in elderly homes, their prioritization will lead to lower COVID-19 related deaths. Accordingly, young and healthy individuals should view vaccine uptake as not only protecting them, but perhaps even more so protecting the more vulnerable socio-demographic groups. Ključne besede: epidemic model, COVID-19, vaccination strategy, vaccination strategy, population heterogeneity, socio-demographic structure, metabolic disease, social network Objavljeno v DKUM: 14.11.2024; Ogledov: 0; Prenosov: 10
Celotno besedilo (7,09 MB) Gradivo ima več datotek! Več... |
8. System design of a vehicle based on the matrix approach using functional analysis of the maintenanceDušan Mežnar, 2021, izvirni znanstveni članek Opis: The use of extended standard functional analysis of maintenance in the design phase of vehicle structure analysis is presented for the first time, where a matrix of the degree of importance of modules or parts, a matrix size between costs and benefits (costs–benefits), and a logistic support matrix (support index and repair time) are used. The use of these methods allows a designer to be able to determine, in the very early phase of the construction process, the important factors (structure, component price, reliability, repair costs, response time, logistic supportability) that have a major impact on vehicle maintenance. Extended functional analysis also allows us to define critical structures in the project specification of vehicles. A crucial issue in functional analysis is the very extensive implementation of research, drawing conclusions and findings with the basic goal of determining a set of indicators for the verification of assumptions and hypotheses. Ključne besede: maintenance, functional analysis, maintenance, vehicle design, structure design Objavljeno v DKUM: 30.09.2024; Ogledov: 0; Prenosov: 6
Celotno besedilo (4,35 MB) Gradivo ima več datotek! Več... |
9. Bioinspired design of 3D-printed cellular metamaterial prosthetic liners for enhanced comfort and stabilityVasja Plesec, Gregor Harih, 2024, izvirni znanstveni članek Opis: Traditional prosthetic liners are often limited in customization due to constraints in manufacturing processes and materials. Typically made from non-compressible elastomers, these liners
can cause discomfort through uneven contact pressures and inadequate adaptation to the complex
shape of the residual limb. This study explores the development of bioinspired cellular metamaterial
prosthetic liners, designed using additive manufacturing techniques to improve comfort by reducing
contact pressure and redistributing deformation at the limb–prosthesis interface. The gyroid unit
cell was selected due to its favorable isotropic properties, ease of manufacturing, and ability to
distribute loads efficiently. Following the initial unit cell identification analysis, the results from the
uniaxial compression test on the metamaterial cellular samples were used to develop a multilinear
material model, approximating the response of the metamaterial structure. Finite Element Analysis
(FEA) using a previously developed generic limb–liner–socket model was employed to simulate
and compare the biomechanical behavior of these novel liners against conventional silicone liners,
focusing on key parameters such as peak contact pressure and liner deformation during donning,
heel strike, and the push-off phase of the gait cycle. The results showed that while silicone liners
provide good overall contact pressure reduction, cellular liners offer superior customization and
performance optimization. The soft cellular liner significantly reduced peak contact pressure during
donning compared to silicone liners but exhibited higher deformation, making it more suitable for
sedentary individuals. In contrast, medium and hard cellular liners outperformed silicone liners for
active individuals by reducing both contact pressure and deformation during dynamic gait phases,
thereby enhancing stability. Specifically, a medium-density liner (10% infill) balanced contact pressure
reduction with low deformation, offering a balance of comfort and stability. The hard cellular liner,
ideal for high-impact activities, provided superior shape retention and support with lower liner
deformation and comparable contact pressures to silicone liners. The results show that customizable
stiffness in cellular metamaterial liners enables personalized design to address individual needs,
whether focusing on comfort, stability, or both. These findings suggest that 3D-printed metamaterial
liners could be a promising alternative to traditional prosthetic materials, warranting further research
and clinical validation Ključne besede: bioinspired design, metamaterial model, cellular structure, additive manufacturing, lower-limb prosthetic, 3D printing, finite element method Objavljeno v DKUM: 19.09.2024; Ogledov: 0; Prenosov: 3
Celotno besedilo (8,88 MB) Gradivo ima več datotek! Več... |
10. Genetska struktura in raznolikost nekaterih tradicionalnih genotipov sliv (Prunus domestica L., Prunus cerasifera Ehrh. in Prunus spinosa L.) : doktorska disertacijaTina Ternjak, 2024, doktorska disertacija Opis: Slovenia has a unique blend of climatic, soil, geographic and historical factors that fostered a rich tradition of plum cultivation and utilization. This study was set up to achieve following objectives: 1. assess the genetic diversity of 124 accessions of the three Prunus species (P. domestica L., P. cerasifera Ehrh., and P. spinosa L.); explore the possible contribution of P. cerasifera and P. spinosa to the ancestry of P. domestica; examine the genetic relationships and variability among the prevalent P. domestica material distributed in Slovenia. A combination of genetic markers, including 11 SSRs (UDP96-005, BPPCT034, EMPAS12, UCD-CH17, EMPAS06, EMPAS11, EMPAS14, BPPCT014, BPPCT025, CPSCT026 and CPPCT006) and three universal cpDNA markers (HK, K1K2 and VL), were chosen alongside flow cytometry. The analysis identified ten cpDNA haplotypes, which were grouped into three clusters using Unweighted Neighbor-Joining (NJ) analysis. All 11 SSR primer pairs exhibited polymorphism, revealing 116 unique genotypes and a total of 328 alleles, indicating considerable diversity with an average of 29.82 alleles per locus. Bayesian analysis distinguished two ancestral populations across all analyzed species. Principal Coordinate Analysis (PCoA) reflected the clustering observed in the Bayesian analysis. When analyzing individual set of P. domestica material, Bayesian analysis also distinguished two ancestral populations across, with PCoA confirming the results of Bayesian analysis. The NJ analysis categorized 71 P. domestica accessions into three clusters with numerous subgroups, reflecting a high genetic diversity. The majority of accessions aligned with traditional pomological groups, such as common prunes, mirabelle plums and greengages.
Genetic diversity parameters were analyzed for the 42 diploid P. cerasifera genotypes. A relatively high diversity levels were found, resulting in 135 alleles, with high average values for alleles per locus (10.38), effective number of alleles (Ne = 5.22), expected heterozygosity (He = 0.77), observed heterozygosity (Ho = 0.64) and PIC value (0.754). In addition, 32 private alleles were found in 20 accessions. Bayesian analysis of the P. cerasifera material revealed three ancestral populations, corroborated by Principal Coordinate Analysis, while an NJ analysis grouped the accessions into three clusters based on the origin of the accession. This study identified valuable local landraces within the P. domestica pool, including traditional prunes or Bluish plums, which are of great genetic interest. Furthermore, the integration of complementary methods facilitated the differentiation of the three species and provided insights into the origin of plum. The findings will be crucial in comprehending the diversity of Slovenian plum germplasm, improving conservation efforts, recovering local genotypes and enriching existing collections of plant genetic resources. Ključne besede: Prunus spp., plum, genetic resources, genetic diversity, genetic structure, cpDNA, SSR Objavljeno v DKUM: 24.07.2024; Ogledov: 160; Prenosov: 43
Celotno besedilo (12,26 MB) |