Iskanje po katalogu digitalne knjižnice

Opis: In this work, we developed a numerical approach based on an experimental platform to determine the working conditions on a cryoplatform and to predict and evaluate the cryogenic printing of hydrogels. Although hydrogels have good biocompatibility, their material properties make it difficult to print them with high precision and shape fidelity. To overcome these problems, a cryogenic cooling platform was introduced to accelerate the physical stabilisation of each deposited layer during the printing process. By precisely controlling solidification (crystallisation), each printed material can withstand its own weight to maintain shape fidelity, and the porosity of the scaffolds can also be controlled more selectively. The thermophysical properties of gelatine hydrogels were investigated to gain a better understanding of the phase change upon freezing. The corresponding material properties and experimental observations of gelatine solidification served as the basis for developing a computational fluid model (CFD) to mimic the solidification of gelatine hydrogels using a cryoplatform at different process conditions and extruder speeds. The goal was to develop a tool simple enough to predict acceptable process conditions for printing gelatine hydrogels using a cryoplatform.
Ključne besede: gelatine, hydrogel, cryoprinting, CFD simulation, solidification modelling
Objavljeno v DKUM: 20.03.2025; Ogledov: 0; Prenosov: 7
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Opis: Purpose: This paper aims to analyse the main variables and causal relationships in the system structure of the diversification of non-agricultural activities on agricultural holdings using system dynamics (SD) modelling. The SD model aims to simulate depictions of the behaviour of the real system while testing the effects of alternative decisions over time. Design/methodology/approach: An SD methodology was chosen to model diversification in farm tourism. Findings: A system approach increases the authors’ understanding of the transition of agricultural holdings to farm tourism. The results indicate that the transition to farm tourism depends on the level of tourism development in a certain area. The system is influenced by subsidies allocated by authorities to expand primary agricultural activities. The model describes a situation in which the tourism and agricultural industries have been affected by the COVID-19 pandemic. Research limitations/implications: The research is limited by the small set of available data due to the limited number of farms in Slovenia. One major problem is the difference in statistical data on the same activity collected from different institutions in Slovenia. Practical implications: The paper includes implications for understanding the transition process to farm tourism, allowing policymakers to experiment with subsidies and promotion to explore the efficacy and efficiency of proposed policies. Originality/value: This study provides a structured, systemic view of the diversification of non-agricultural activities on agricultural holdings, where the simulation results are a reliable reflection of the behaviour of the actual system being modelled.
Ključne besede: system dynamics, modelling, simulation, diversification, farm tourism, farm policy, Slovenia, simulation scenarious
Objavljeno v DKUM: 11.12.2024; Ogledov: 0; Prenosov: 5
Celotno besedilo (1,20 MB)
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Opis: Over the past decades, container transportation management has become an important part of the global maritime industry. Due to an ever-increasing movement of containers across the globe in line with the economic boom, the trade imbalance and issues related to empty containers have become inevitable. The accumulation of empty containers in specific ports not only causes a waste of money but also increases the environmental footprint. Accordingly, the urgent need for empty container management has been gaining more attention than ever before, as the shipping companies recognized that more revenues are always derived from a good repositioning strategy. In this respect, this thesis described state-of-the-art of empty container management, focusing on the practices concerning the movement of empty containers that are varied between organizational policies, technical solutions, and optimization applications. With the development of computer-aided systems, the combination of optimization and simulation models has been proposed to tackle the maritime empty container problem. The thesis shows how the strengths of optimization-based simulation can be integrated to provide high-quality solutions with low computational costs. Agent-based modelling was developed to model the global movements of empty containers, providing realistic details of interactions among entities and characteristics of components within the system. The model was applied between ports in the Middle East and Asia for one of the biggest shipping lines worldwide. By using simulated annealing (SA), the best sequence for moving containers can be determined. The results comparison demonstrate that the proposed optimised repositioning strategy can significantly reduce the shipping line’s costs and make full use of empty containers in the planning horizon.
Ključne besede: shipping industry, container transportation management, empty container repositioning, simulation, optimization, agent-based modelling
Objavljeno v DKUM: 08.12.2023; Ogledov: 579; Prenosov: 29
Celotno besedilo (3,38 MB)

Ključne besede: metaheuristic algorithm, improved multi-phase particle swarm optimization, cellular neighbor network, dynamic job shop scheduling, simulation modelling
Objavljeno v DKUM: 19.05.2023; Ogledov: 527; Prenosov: 49
Celotno besedilo (5,62 MB)
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Opis: Background and Purpose: The aim of this paper is to present the influence of Industry 4.0 on the development of the new simulation modelling paradigm, embodied by the Digital Twin concept, and examine the adoption of the new paradigm via a multiple case study involving real-life R&D cases involving academia and industry. Design: We introduce the Industry 4.0 paradigm, presents its background, current state of development and its influence on the development of the simulation modelling paradigm. Further, we present the multiple case study methodology and examine several research and development projects involving automated industrial process modelling, presented in recent scientific publications and conclude with lessons learned. Results: We present the research problems and main results from five individual cases of adoption of the new simulation modelling paradigm. Main lesson learned is that while the new simulation modelling paradigm is being adopted by big companies and SMEs, there are significant differences depending on company size in problems that they face, and the methodologies and technologies they use to overcome the issues. Conclusion: While the examined cases indicate the acceptance of the new simulation modelling paradigm in the industrial and scientific communities, its adoption in academic environment requires close cooperation with industry partners and diversification of knowledge of researchers in order to build integrated, multi-level models of cyber-physical systems. As shown by the presented cases, lack of tools is not a problem, as the current generation of general purpose simulation modelling tools offers adequate integration options.
Ključne besede: simulation, modelling, automated modelling, Industry 4.0, Digital Twin, SME, multiple-case study
Objavljeno v DKUM: 30.11.2017; Ogledov: 1571; Prenosov: 541
Celotno besedilo (1,07 MB)
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