Iskanje po katalogu digitalne knjižnice

Opis: Interior permanent magnet synchronous machines (IPMSMs) driven with a square-wave control (i.e., six-step, block, or 120◦ control), known commonly as brushless direct current (BLDC) drives, are used widely due to their high power density and control simplicity. The advance firing (AF) angle is employed to achieve improved operation characteristics of the drive. The AF angle is, in general, applied to compensate for the commutation effects. In the case of an IPMSM, the AF angle can also be adjusted to exploit reluctance torque. In this paper, a detailed study was performed to understand its effect on the drive’s performance in regard to reluctance torque. Furthermore, a multiobjective optimization of the machine’s cross-section using neural network models was conducted to enhance performance at a constant AF angle. The reference and improved machine designs were evaluated in a system-level simulation, where the impact was considered of the commutation of currents. A significant improvement in the machine performance was achieved after optimizing the geometry and implementing a fixed AF angle of 10◦.
Ključne besede: MTPA, maximum torque per ampere, IPM SM, interior permanent magnet synchronous machine, BLDC, brushless direct current drive, rotor optimization, square-wave control, advance firing angle, neural network
Objavljeno v DKUM: 13.01.2026; Ogledov: 0; Prenosov: 1
Celotno besedilo (2,87 MB)
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Opis: Reconfigurable Manufacturing Systems (RMSs) are widely used to produce small batches of customized products in the current manufacturing environment. We comprehensively optimized the assembly transport strategy, production process, and production configuration of a reconfigurable flow shop (RFS). Firstly, three assembly transfer strategies, one-to-one, one-to-many, and many-to-many, are proposed for an RFS, given the specific process limitations. In addition, a production simulation model of the RFS is established by the Plant Simulation software to verify and compare those three strategies with realistic production constraints considered. Moreover, the production processes are optimized, and the optimal buffer configuration and vehicle configuration are optimized by the design of experiment (DOE) method. After the optimization processes, the throughput and facility utilization under each strategy increases significantly. Additionally, the optimal buffer size and vehicle quantity under each strategy are determined and compared. The one-to-one strategy can maximize the production output, but it requires the most production resources. In addition, the many-to-many strategy is more efficient than the one-to-many strategy. Our study provides a variety of assembly transport strategies for an RFS and offers an efficient optimization method for production performance and production configuration.
Ključne besede: Reconfigurable Manufacturing Systems, discrete event simulation, assembly transport strategy, optimization, plant simulation, reconfigurable flow shop, production configuration, simulation modelling
Objavljeno v DKUM: 13.01.2026; Ogledov: 0; Prenosov: 0
Celotno besedilo (2,59 MB)
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Opis: In the article “New Technological Approach to Cable Car Boarding”, the authors attempted to correctly design the curve geometrically along which the rope moves through the station during the deceleration of cabins with attaching platforms in a central position, primarily intended for mass public transport. Since the suspension continuously connects the cabin and the rope during cabin deceleration, the rope moves at a constant speed along a special curve that enables the cabin to stop in the central position. This curve is symmetric with respect to the longitudinal axis of the station. However, the authors found that in the previous article presenting this cable car system, an error was made in the geometric design of the rope path curve, which the original authors were not aware of at the time. They determined that, in the presented example, a suspension length of 8 m was too short for the combination of rope speed of 5 m/s (cable car speed) and cabin deceleration of 0.5 m/s2. This article revisits this geometric problem in greater detail. The study shows that not every combination of rope speed, suspension length, and cabin deceleration in the central position functions correctly. First, the boundary conditions and spatial constraints of the rope path curve were defined. Based on the upper bound and lower bound rope path lengths, the optimal or correct shape of the rope path curve was determined geometrically. The study concludes that for a given combination of rope speed (cable car speed) and cabin deceleration, only one suspension length is suitable. In the case of a rope speed of 5 m/s and cabin deceleration of 0.5 m/s2, the correct suspension length is 16.85 m. The authors also found that the result depends on the time interval used in constructing the curve.
Ključne besede: cable cars, rope path curve, geometric modeling, cabin deceleration, attaching platforms, suspension length optimization, public transport, high-capacity transit
Objavljeno v DKUM: 18.12.2025; Ogledov: 0; Prenosov: 2
Celotno besedilo (1,51 MB)
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Opis: This paper presents numerical solving of the inverse bioheat problem to estimate four skin cancer parameters; diameter, thickness, blood perfusion rate and thermal relaxation time, based on the thermal response on the skin surface obtained by dynamic thermography and numerical skin cancer model, which can greatly enhance dynamic thermography diagnostics. To describe the heat transfer inside biological tissue and thermal behavior during the dynamic thermography process as realistic as possible, the non-Fourier dual-phase-lag bioheat model was used, as well as skin cancer model has been composed of multilayered healthy skin, embedded skin tumor and subcutaneous fat and muscle. Boundary element method has been used to solve a complex non-Fourier bioheat model to simulate dynamic thermography based on the skin cancer model and guessed searched parameters to obtain the thermal response on the skin surface during the cooling and rewarming phase using a cold air jet provocation, which is needed for the solution of the inverse bioheat problem. The inverse problem has been solved by optimization approach using the hybrid Levenberg-Marquardt optimization method, while the measurement data has been generated numerically with known exact tumor parameters and added noise, to evaluate the accuracy and sensitivity of the solution. Inverse problem solution has been tested for two different thermal responses; absolute temperature and temperature difference response, as well as for two different tumor stages; early stage or Clark II and later stage or Clark IV tumor. All important tumor parameters were successfully retrieved, especially the diameter and relaxation time, even for the high level of noise, while the accuracy of obtained parameters is slightly better using absolute temperature response. The results demonstrate the robustness of the method and a promising way for early diagnosis. The findings contribute to improving bioheat modeling in biological tissues, solving inverse bioheat problems and advancing dynamic thermography as a non-invasive tool for early skin cancer diagnosis.
Ključne besede: numerical modeling, dynamic thermography, inverse problem, non-Fourier bioheat transfer, dual-phase-lag model, boundary element method, Levenberg-Marquardt optimization
Objavljeno v DKUM: 09.12.2025; Ogledov: 0; Prenosov: 6
Celotno besedilo (1,83 MB)
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Opis: Axial flux permanent magnet machines have garnered significant attention in recent years due to their numerous advantages in various applications, including electric vehicles, wind turbines, and robotics. However, one of the critical challenges associated with these machines is the presence of cogging torque, which can hinder their efficiency and performance. This review article provides a comprehensive overview of the state-of-the-art techniques employed for cogging torque reduction in Axial Flux Permanent Magnet Machines. Different techniques are described, encompassing geometric optimization, magnet placement, and skewing methods. Firstly, the significance of Axial Flux Permanent Magnet Machines is described, as well as the issue of the cogging torque. In the methods section, a review of the strategies for the reduction of cogging torque is described from various articles, and finally, in the discussion section, a list of actions is presented for cogging torque reduction for different topologies. The novelty of the study is that it combines strategies for cogging torque reduction in a single article.
Ključne besede: cogging torque, axial flux permanent magnet machines, geometric optimization, magnet placement strategies, skewing techniques
Objavljeno v DKUM: 06.11.2025; Ogledov: 0; Prenosov: 3
Celotno besedilo (6,51 MB)
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