| 1. |
- Atalaya, Juan, 1981, et al.
(author)
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Design and optimization of coreless components using admittance matrix and efficiently calculated sensitivities
- 2007
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In: IEEE Transactions on Magnetics. ; 43, s. 1621-1624
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Journal article (peer-reviewed)abstract
- This paper presents a novel technique for designing coreless components (inductors and transformers) based on the admittance matrix at quasi-static approximation. In addition, an optimization method based on continuum sensitivity is applied. Efficiency of the design method is shown for inductors that have axisymmetry and carry azimuthal currents. In order to avoid coupling between closely located inductors, a shielding structure is proposed and shape-optimized to confine the magnetic energy.
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| 2. |
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| 3. |
- Bissal, Ara, 1986-, et al.
(author)
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Loadability and scaling aspects of Thomson based ultra-fast actuators
- 2012
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In: Actuator 2012.
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Conference paper (peer-reviewed)abstract
- In this paper, an ultra-fast single-sided Thomson based actuator is studied. The actuator is comprised of a flat spiral-shaped coil with a conductive armature in its proximity. This armature is mechanically loaded with a uniform mass distribution over its cross section. The energizing source consists of a capacitor bank that is discharged through the actuator coil resulting in a high magnetic pressure within fractions of a millisecond. The coil is dimensioned to withstand the temperature rise.An experimentally validated multi-physical finite element model is used to perform simulations by varying the mechanical load to explore the performance of the actuator topology. The obtained currents, induced forces, stresses, and accelerations of the armature are then analyzed in an attempt to develop scaling techniques that can predict for example velocity and efficiency. Finally, the results of the scaling techniques are presented and compared to each other.
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| 4. |
- Bissal, Ara, et al.
(author)
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Multiphysics modeling and experimental verification of ultra-fast electro-mechanical actuators
- 2015
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In: International journal of applied electromagnetics and mechanics. - 1383-5416 .- 1875-8800. ; 49:1, s. 51-59
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Journal article (peer-reviewed)abstract
- In this paper, a multi-physics computational tool has been developed to accurately model and build high performance ultra-fast actuators. The research methodology is based on a finite element method model coupled with a circuit model. Electromagnetic, thermal, mechanical, and algebraic equations are implemented in Comsol Multiphysics and verified with laboratory experiments of a built prototype. A simplified model is preferred as long as its underlying assumptions hold. However, in the presence of large current and force densities, nonlinearities such as deformations may occur. Such phenomena can only be captured by the use of the developed comprehensive multi-physics simulation model. Although this model is computationally demanding, it was shown to have an accuracy of at least 95% when compared with experiments.
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| 5. |
- Bissal, Ara, et al.
(author)
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On the Design of a Linear Composite Magnetic Damper
- 2015
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In: IEEE transactions on magnetics. - : IEEE Press. - 0018-9464 .- 1941-0069. ; 51:11
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Journal article (peer-reviewed)abstract
- High-voltage direct current (HVdc) breakers are the key components in the realization of multiterminal HVdc grids. In the presence of fault current, these breakers should be able to deliver impulsive forces to swiftly open the metallic contacts. After the acceleration phase, the moving armature should be decelerated using controllable forces to avoid plastically deforming fragile components integrated in the system. In this paper, finite-element method-based simulation models, complimented with small-scale and large-scale experimental prototypes, were utilized to benchmark different damping topologies. It was found that a Halbach-based configuration can deliver a damping force that is almost two and a half times larger than its sequel. Its sequel, composed of vertically stacked oppositely oriented magnets, is easier to assemble and is also capable of generating a considerable damping force. Finally, it has been shown that both these schemes, inserted in a composite tube, have a potential to be used as dampers in HVdc breakers.
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| 6. |
- Bissal, Ara, 1986-, et al.
(author)
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On the Design of Ultra-Fast Electromechanical Actuators : A Comprehensive Multi-Physical Simulation Model
- 2012
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In: Sixth International Conference on Electromagnetic Field Problems and Applications (ICEF), 2012. - : IEEE conference proceedings. - 9781467313339 ; , s. 1-4
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Conference paper (peer-reviewed)abstract
- In this paper, a simulation of an ultra-fast electromechanical drive was performed by using a two-dimensional axi-symmetric multi-physical finite element model. The aim of this paper is to primarily show that the following model can be used to simulate and design those actuators with good accuracy, secondly, to study the behavior and sensitivity of the system and thirdly, to demonstrate the potential of the model for industrial applications. The simulation model is coupled to a circuit and solves for the electro-magnetic, thermal, and mechanical dynamics utilizing a moving mesh. The actuator under study is composed of a spiral-shaped coil and a disk-shaped 3mm thick copper armature on top. Two numerical studies of such an actuator powered by 2640 J capacitor banks were performed. It is shown that forces up to 38 kN can be achieved in the range of 200 μs. To add credibility, a benchmark prototype was built to validate this experimentally with the use of a high speed camera and image motion analysis.
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| 7. |
- Salinas, Ener, 1957, et al.
(author)
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A new technique for reducing extremely low frequency magnetic field emissions affecting large building structures
- 2007
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In: Environmentalist. - 0251-1088 .- 1573-2991. ; 27:4, s. 571-576
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Journal article (peer-reviewed)abstract
- When large structures such as residentialcompounds or public buildings are under the influence ofextremely low frequency (ELF) magnetic fields, such asthe one generated by a system of railways fed by16.67 Hz, standard methods of designing shieldingstructures by numerical methods usually fail. The lattercan be explained by the difficulty posed in the computingprocess by the large aspect ratios involved due to thinlayers of metal (a few millimetres or centimetres) incontrast to the large dimensions of the affected structure(several tens of meters). In some cases one has to utilizespecial approximations such as surface conductivity,which are not easy to handle when the designed shieldingstructure is clearly three -dimensional. Other alternativessuch as experimentation in situ are very costly. Here, anew technique is presented of mitigating the field byusing three-dimensional propagation of induced currentsoptimizing the field reduction factors and minimizing thecost of shielding material. The particular designingmethod is a hybrid of numerical simulations combinedwith lab experimentation using scaled models of the largestructure. The method is rather cost-effective and flexible as various designs can be easily tested. Results are presented in the form of magnetic field values, at various locations in the buildings, before and after this mitigation technique is applied.
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| 9. |
- Salinas, Ener, 1957
(author)
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Mitigation of Power-Frequency Magnetic Fields With Applications to Substations and Other Parts of the Electric Network
- 2001
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Doctoral thesis (other academic/artistic)abstract
- In recent times, electromagnetic emissions from various electrical components have induced more than one debate whether they represent a harmful influence to our health. In addition, interferences caused by power frequency magnetic fields (PFMFs) on electron beam based electronic equipment (e.g. cathode ray tubes found in TV screens and computer monitors, electron microscopes) become evident at levels over 1 microtesla. These issues have caused some concern with the general public but also to the utilities, their customers and the electromagnetic compatibility community. On the other hand, they have also spurred efforts to study and mitigate these fields. Although most published studies and debates are concerned with fields from power transmission lines, similar levels of PFMFs can be found in a city neighbourhood. For this reason this study focuses on the fields originating from the last stages of the power network before reaching the customer, in particular the components of in-house secondary substations. However the methods developed in this study can also be applied more generally. Conductive and ferromagnetic shielding, passive and active compensation and other techniques are described. These techniques make use of modern methods of analysis such as algebraic computing and 2D/3D modelling. It was found that shielding using thin conductive plates and a proper design can provide for cost-effective mitigation of PFMFs. It was shown that the choice of either ferromagnetic or conductive shielding is dependant on a number of variables, which can only be determined by a proper 2D or 3D modelling. It was also found that cable and busbar connections and not the transformers are the main cause of large PFMF emission from substations. These and other results were applied to actual cases where the measured values were considered as problematic, or where low emission was a requirement already at the design stages.
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| 11. |
- Yu, Runze, et al.
(author)
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Real-time inspection and fault detection for large photovoltaic arrays based on drones and deep learning algorithms
- 2023
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In: Journal of Physics: Conference Series 2678. - : IOP Publishing.
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Conference paper (peer-reviewed)abstract
- In recent years, the installation of renewable energy generation systems based on photovoltaic (PV) panels has experienced massive increments and PV parks with thousands of panels are now becoming commonplace. Yet, there are some challenges, like inspection and fault detection. Lately, these operations have been approached using drones. This project adds the use of deep learning, more specifically proposes the convolutional neural network (CNN) algorithm, the YOLOv5 model and Real-Time Messaging Protocol (RTMP) protocol to achieve real-time detection of PV panels failures. The YOLOv5 model was trained by sets sorted into 9 different categories including fault and abnormal objects' coverage. This multi-class classification system was investigated by a variety of evaluation indexes to show effectiveness and accuracy. The system was also examined with its different fault classes. The performance results demonstrate that the mean average precision could reach up to 98% with a good training set, confirming the feasibility of proposed approaches.
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