Iskanje po katalogu digitalne knjižnice

Opis: This research explores the viability of producing ISO G-code for 3-axis machining with OpenAI's Chat Generative Pre-Trained Transformer models, particularly ChatGPT-3.5 and the newer GPT-4o. G-code (RS-274-D, ISO 6983) converts human directives into commands that machines can understand, controlling toolpaths, spindle velocities, and feed rates to produce particular aspects of an object. Previously, G-code was generated either by hand or through the use of computer-aided manufacturing (CAM) software along with machine-specific post-processors, both of which may require considerable time and expense. This research aimed to assess the practicality and effectiveness of specific large language models (LLMs) in generating G-code. The assessment took place in three distinct phases on a sample component that required 3-axis machining. These phases included: (1) the self-generated production of G-code for the sample component, (2) the examination of the independently generated G-code in the CAM application, and (3) the recognition and justification of mistakes in the G-code. The outcomes indicated varying abilities with promising findings. This method could accelerate and possibly enhance manufacturing workflows by decreasing reliance on expensive CAM software and specialized knowledge.
Ključne besede: generative artificial intelligence, intelligent manufacturing, large language models (LLM), ChatGPT, CNC machining, G-code programming
Objavljeno v DKUM: 28.11.2025; Ogledov: 0; Prenosov: 11
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Opis: The synthesis of heat exchanger networks (HENs) is an NP hard problem, made even more difficult by the requirement of commercial software licenses and coding ability. This paper introduces OpenHENS, a first-of-itskind open-source tool for HEN synthesis. In the literature, HEN synthesis based on mathematical programming almost exclusively relies on commercial MINLP (mixed-integer non-linear programming) solvers (e.g., BARON, Gurobi, etc.). Open source MINLP solvers, in contrast, lack the robustness, scalability and quality that are the hallmarks of commercial solvers. To overcome this challenge, OpenHENS embeds a novel three-step synthesis method that gradually increases the complexity of the model. The first two steps identify economically viable and thermodynamically feasible heat exchanger matches, removing the non-viable matches and reducing the problem size. In the third step, numerous HEN designs are obtained by evolving promising networks to obtain families of near-optimal solutions. OpenHENS was tested on thirteen benchmark problems and seven of the solutions were within 2 % of the total annualised cost (TAC) best-known solutions from literature. In eleven of the benchmark problems, OpenHENS returned more than 10 unique networks within 2 % of the best solution, enabling the engineer to select the most practical design with minimal cost difference. OpenHENS demonstrates that open-source software, when developed correctly, offers comparable performance to commercial software while promoting greater accessibility in industry.
Ključne besede: heat exchanger network, process integration, optimization, mathematical programming, open source, Phyton
Objavljeno v DKUM: 03.11.2025; Ogledov: 0; Prenosov: 1
Celotno besedilo (17,21 MB)

Opis: At Štore Steel Ltd., continuously cast billets (180 mm × 180 mm) are reheated and rolled after cooling to room temperature. Hot-rolled bars are controlled as they cool to room temperature in specially designed cooling chambers, minimizing residual stresses and the development of pre-existing surface and internal defects. The bar ends can be additionally covered with insulating material. The cooled, rolled bars undergo examination using automated control lines to detect surface and internal defects, which primarily originate from the casting process. Internal defects are identified using ultrasonic testing. Between January 2022 and June 2023, 1550.0 tons of 61SiCr7 rolled bars, with diameters ranging from 53 mm to 72 mm and lengths from 7010 mm to 7955 mm, were examined using ultrasonic testing. The scrap was 109.6 tons (7.07 %). After collecting data on chemical composition (C, Si, Mn, Cr, Mo, Ni content), the casting process (casting temperature, cooling water pressure and flow in the first, second, and third zones of secondary cooling, as well as the temperature difference between input and output mould cooling water), and rolled bar geometry (diameter, length), scrap modelling after ultrasonic testing was carried using genetic programming. The genetic programming model suggested reducing the length of the rolled bar. Due to length multiplication, it was possible to reduce the rolled bar length from the initial lengths of 7010-7955 mm to the current lengths of 4558-6720 mm in June 2023. Based on this adjustment, a new production of rolled bars was established. By August 2024, 1251.9 tons of 61SiCr7 rolled bars were produced with the mentioned length adjustments. These rolled bars were subsequently examined using ultrasonic testing. The scrap was reduced by nearly 14 times, amounting to only 8.1 tons (0.64 %).
Ključne besede: steel industry, rolling, long bars, ultrasonic testing, scarp, defects, modelling, genetic programming
Objavljeno v DKUM: 27.08.2025; Ogledov: 0; Prenosov: 3
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Opis: This study deals with berth allocation for Maritime Autonomous Surface Ships (MASSs) in the context of the mixed operation of MASSs and manned vessels from the perspective of port-shipping companies’ collaboration. Two berth allocation strategies, namely the separated-type and the mixed-type, are proposed in this article. Two mixed integer nonlinear programming models aimed at minimizing the total docking cost of the vessels in the port and the waiting time for berths are developed and solved using Gurobi, respectively. A large-scale simulation of the mixed-type berth allocation model is carried out using an improved simulated annealing algorithm. Several experiments are conducted to test the effectiveness of the model and to draw insights for commercializing autonomous vessels. The presented results show that multi-objective modeling and optimization should be conducted from the collaboration of port-shipping companies, which is more efficient from the perspective of shipping companies or ports, respectively. When berth resources are limited or there is a high requirement for operational safety, the separated-type berth allocation strategy is more efficient. When the number of MASS-dedicated berths reaches a certain proportion, the total docking cost of the vessel no longer changes, indicating that more dedicated berths are not better.
Ključne besede: maritime autonomous surface ship (MASS), mixed operation scenarios, berth allocation, mixed integer programming, simulated annealing algorithm, port-shipping companies’ collaboration
Objavljeno v DKUM: 18.06.2025; Ogledov: 0; Prenosov: 1
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Opis: A series of distributed flexural cracks develop in reinforced concrete flexural elements under the working load. The control of cracking in reinforced concrete is an important issue that must be considered in the design of reinforced concrete structures. Crack width and spacing are influenced by several factors, including the steel percentage, its distribution in the concrete crosssection, the concrete cover, and the concrete properties. In practice, however, a compromise must be made between cracking, durability, and ease of construction and cost. This study presents the optimal design of a reinforced concrete cross-section, using the optimization method of mixed-integer nonlinear programming (MINLP) and the Eurocode standard. The MINLP optimization model OPTCON was developed for this purpose. The model contains the objective function of the material cost considering the crack width requirements. The crack width requirements can be satisfied by direct calculation or by limiting the bar spacing. Due to the different crack width requirements, two different economic designs of reinforced concrete sections were proposed. The case study presented in this study demonstrates the value of the presented optimization approach. A direct comparison between different methods for modelling cracking in reinforced concrete cross-sections, which has not been done before, is also presented.
Ključne besede: crack width, cost optimization, optimal design, mixed-integer non-linear programming
Objavljeno v DKUM: 13.03.2025; Ogledov: 0; Prenosov: 8
Celotno besedilo (1,55 MB)
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