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- 摘要
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- 实验方案
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Thermal oxidative decomposition estimation combining TGA and DSC as optimization targets for PMMA
摘要： Thermal analysis techniques play a key role to determine and characterize solid phase thermal decomposition. In this sense, Simultaneous Thermal Analysis (STA, i.e. TGA and DSC tests carried out simultaneously) are widely employed, since it provides information about how mass is lost and energy released while the temperature of the sample increases. Fire computer models combined with methods numerical methods are widely used to represent the results from tests and to achieve the values of the kinetic and thermal parameters. Previous works looked forward achieving those parameters using, as unique optimization target, the mass loss curve (TGA) or its derivative (DTGA). As the study of heat release rate is a decisive element to characterize the material properly, most recent works were adding additional measures. These extra measurements concern the heat transfer and the energy required or released during temperature programmed heating, such as heat rate release, heat of gasification, or the surface temperatures of the samples. The information about the energy is provided by the Differential Scanning Calorimetry curve (DSC). Despite of the employment of the information provided by the DSC, this information usually is not used as a target to approach the DSC simulated curve to the experimental one as TGA does. Based on the lack of use of the DSC curve as numerical approaching process to set the kinetic properties, we decide to explore the possibility of adding this as a new target in the process. Therefore, kinetic and thermal properties might be achieved fitting experimental and simulated curves simultaneously, which should allow us to take into account the decomposition process and their energy released. Results obtained in the present work reveal the major challenge of getting a set of parameters, which can fit DSC curve. The level of accuracy reached when only TGA is utilized as target to approach is higher than the level of accuracy of DSC curve. This fact makes increase the value of the errors when both curves are used as targets to approach. In other words, an approach to both curves simultaneously cannot be directly made. With this consideration in mind, this paper proposes an alternative methodology in order to fit TGA curve considering the optimization of the DSC curve. The methodology proposed in the present work is applied to the analysis of poly(methyl methacrylate) (PMMA).
关键词： DSC,numerical methods,TGA,CFD,Thermal decomposition,PMMA,optimization methods,solid phase chemistry
更新于2025-09-23 15:23:52
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Optimal Switching Operation of PT-Symmetric Dimmers with Nonuniform Gain/Loss and Coupling Profiles
摘要： We assess through a variational optimization approach the optimal gain-loss profile for a non-uniform PT-symmetric coupler allowing the realization of a binary transfer function and minimizing the deviation of the total traveling light intensity as compared to that holding in a conservative system. We bring evidence that the gain-loss profile fulfilling this requirement corresponds to a non-conventional situation when light intensity is conserved in every point along the propagation distance in the PT-symmetric system. Furthermore, the optimal profile thus found corresponds to a practically important case of optical switching operation achieved with a minimal amount of amplification level. We show that switching architectures using such type of gain-loss profiles are very substantially advantageous as compared to conventional uniform PT-symmetric couplers. Furthermore, this type of optimal profile turns out to be robust with respect to fabrication imperfections. This opens new prospects for functional applications of PT-symmetric devices in photonics.
关键词： variational and optimization methods,parity-time symmetry,optical switches,waveguides and couplers
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Developing Inkjet Printed PEDOT/PSS Films for Solar Cells
摘要： This paper deals with the impact of a gas discharge arrester's electrodes' shapes on its performance. When after extinguishing the electric arc between the electrodes of the gas discharge arrester and the electric-field strength between the electrodes exceeds the critical value, reignition occurs. Computation of the electric-field strength between the electrodes of the existing gas discharge arresters using the finite elements method shows that electric-field strength reaches its highest values at the edges of the electrodes. It therefore makes sense to reduce the electric-field strength at the edges of the electrodes by changing the electrodes' shapes. This also reduces the risk of reigniting the electric arc between the electrodes and improves the arrester's ability to self-extinguish. The electrodes can be geometrically shaped in such a way that ensures much uniform distribution of the electric-field strength as possible. This paper describes the model of a gas discharge arrester and the use of a differential evolution optimization algorithm for computation of the more adequate shapes of electrodes. Thus, uniform distribution of the electric-field strength is ensured between the gas discharge arrester electrodes.
关键词： optimization methods,Finite-element methods,overvoltage protection,gas discharge arrester (GDA)
更新于2025-09-23 15:19:57
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - VIS-NIR GeSi Photodetector with Voltage Tunable Spectral Response
摘要： An innovative double-sided tubular linear induction motor is presented, and its optimal design in terms of thrust force is discussed. A dedicated semi-analytical model of the device is developed allowing for fast and accurate evaluation of all the electromechanic quantities in the device, including the thrust force, back-electromotive force, distribution of the induced current, and average magnetic flux density in the teeth. This provides a basis for the design optimization, which has been performed by a novel evolutionary algorithm based on the self-organizing maps. Using the semi-analytical formulation, the characterization of the machine is greatly facilitated, thus allowing a fast evaluation of the cost function and design constraints. Finally, the obtained optimal design is validated by comparison with finite elements method analysis.
关键词： linear motors,Electromagnetic analysis,induction motors,induction accelerators,optimization methods
更新于2025-09-23 15:19:57
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[IEEE 2019 Workshop on Recent Advances in Photonics (WRAP) - Guwahati, India (2019.12.13-2019.12.14)] 2019 Workshop on Recent Advances in Photonics (WRAP) - Shadowgraphic Imaging of Cavitation Bubble Dynamics in Pulsed Laser Ablation of a Solid in Liquid
摘要： Insulated-gate bipolar transistor (IGBT) power modules find widespread use in numerous power conversion applications where their reliability is of significant concern. Standard IGBT modules are fabricated for general-purpose applications while little has been designed for bespoke applications. However, conventional design of IGBTs can be improved by the multiobjective optimization technique. This paper proposes a novel design method to consider die-attachment solder failures induced by short power cycling and baseplate solder fatigue induced by the thermal cycling which are among major failure mechanisms of IGBTs. Thermal resistance is calculated analytically and the plastic work design is obtained with a high-fidelity finite-element model, which has been validated experimentally. The objective of minimizing the plastic work and constrain functions is formulated by the surrogate model. The nondominated sorting genetic algorithm-II is used to search for the Pareto-optimal solutions and the best design. The result of this combination generates an effective approach to optimize the physical structure of power electronic modules, taking account of historical environmental and operational conditions in the field.
关键词： fatigue,power cycling (PC),insulated-gate bipolar transistors (IGBTs),thermal cycling (TC),reliability,optimization methods,finite-element (FE) methods,Aging,multiobjective
更新于2025-09-19 17:13:59
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[IEEE IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Lisbon, Portugal (2019.10.14-2019.10.17)] IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Techno-Economic Analysis of Building Integrated Photovoltaics Electrical Installations
摘要： Insulated-gate bipolar transistor (IGBT) power modules find widespread use in numerous power conversion applications where their reliability is of significant concern. Standard IGBT modules are fabricated for general-purpose applications while little has been designed for bespoke applications. However, conventional design of IGBTs can be improved by the multiobjective optimization technique. This paper proposes a novel design method to consider die-attachment solder failures induced by short power cycling and baseplate solder fatigue induced by the thermal cycling which are among major failure mechanisms of IGBTs. Thermal resistance is calculated analytically and the plastic work design is obtained with a high-fidelity finite-element model, which has been validated experimentally. The objective of minimizing the plastic work and constrain functions is formulated by the surrogate model. The nondominated sorting genetic algorithm-II is used to search for the Pareto-optimal solutions and the best design. The result of this combination generates an effective approach to optimize the physical structure of power electronic modules, taking account of historical environmental and operational conditions in the field.
关键词： power cycling (PC),Aging,fatigue,insulated-gate bipolar transistors (IGBTs),thermal cycling (TC),multiobjective,optimization methods,reliability,finite-element (FE) methods
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - a-Si:H/c-Si interface hydrogenation for implied V <sub/>oc</sub> = 755 mV in Silicon heterojunction solar cell
摘要： Insulated-gate bipolar transistor (IGBT) power modules find widespread use in numerous power conversion applications where their reliability is of significant concern. Standard IGBT modules are fabricated for general-purpose applications while little has been designed for bespoke applications. However, conventional design of IGBTs can be improved by the multiobjective optimization technique. This paper proposes a novel design method to consider die-attachment solder failures induced by short power cycling and baseplate solder fatigue induced by the thermal cycling which are among major failure mechanisms of IGBTs. Thermal resistance is calculated analytically and the plastic work design is obtained with a high-fidelity finite-element model, which has been validated experimentally. The objective of minimizing the plastic work and constrain functions is formulated by the surrogate model. The nondominated sorting genetic algorithm-II is used to search for the Pareto-optimal solutions and the best design. The result of this combination generates an effective approach to optimize the physical structure of power electronic modules, taking account of historical environmental and operational conditions in the field.
关键词： fatigue,power cycling (PC),insulated-gate bipolar transistors (IGBTs),thermal cycling (TC),reliability,optimization methods,finite-element (FE) methods,Aging,multiobjective
更新于2025-09-19 17:13:59
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[IEEE 2018 Progress in Electromagnetics Research Symposium (PIERS-Toyama) - Toyama (2018.8.1-2018.8.4)] 2018 Progress in Electromagnetics Research Symposium (PIERS-Toyama) - A New Waveguide Technology with a Ridge and Surrounding Metal Rods of <tex>$\lambda/4$</tex> in Height and its Applications
摘要： This paper deals with the impact of a gas discharge arrester's electrodes' shapes on its performance. When after extinguishing the electric arc between the electrodes of the gas discharge arrester and the electric-field strength between the electrodes exceeds the critical value, reignition occurs. Computation of the electric-field strength between the electrodes of the existing gas discharge arresters using the finite elements method shows that electric-field strength reaches its highest values at the edges of the electrodes. It therefore makes sense to reduce the electric-field strength at the edges of the electrodes by changing the electrodes' shapes. This also reduces the risk of reigniting the electric arc between the electrodes and improves the arrester's ability to self-extinguish. The electrodes can be geometrically shaped in such a way that ensures much uniform distribution of the electric-field strength as possible. This paper describes the model of a gas discharge arrester and the use of a differential evolution optimization algorithm for computation of the more adequate shapes of electrodes. Thus, uniform distribution of the electric-field strength is ensured between the gas discharge arrester electrodes.
关键词： optimization methods,Finite-element methods,overvoltage protection,gas discharge arrester (GDA)
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Beam Shaping with Higher Laguerre-Gaussian Orders for High Power Bessel Beams
摘要： This paper deals with the impact of a gas discharge arrester's electrodes' shapes on its performance. When after extinguishing the electric arc between the electrodes of the gas discharge arrester and the electric-field strength between the electrodes exceeds the critical value, reignition occurs. Computation of the electric-field strength between the electrodes of the existing gas discharge arresters using the finite elements method shows that electric-field strength reaches its highest values at the edges of the electrodes. It therefore makes sense to reduce the electric-field strength at the edges of the electrodes by changing the electrodes' shapes. This also reduces the risk of reigniting the electric arc between the electrodes and improves the arrester's ability to self-extinguish. The electrodes can be geometrically shaped in such a way that ensures much uniform distribution of the electric-field strength as possible. This paper describes the model of a gas discharge arrester and the use of a differential evolution optimization algorithm for computation of the more adequate shapes of electrodes. Thus, uniform distribution of the electric-field strength is ensured between the gas discharge arrester electrodes.
关键词： optimization methods,Finite-element methods,overvoltage protection,gas discharge arrester (GDA)
更新于2025-09-16 10:30:52
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Quasi-Phase-Matching Efficiency Optimization for Coupled Second-Order Nonlinear Processes
摘要： It is well known how to tailor the conversion ef?ciency grid of a single quasi-phase-matching (QPM) grating when the involved processes are uncoupled. However, it becomes much more sophisticated in the presence of coupling between multiple processes. In this case, different processes compete for the same QPM “resources” throughout the grating, and one process can outweigh the others over a certain range of interaction. Here we propose the generalized iterative domino (GID) algorithm to meet these challenges for the ?rst time (to our best knowledge). Instead of tailoring the strength of each “global” Fourier coef?cient, GID algorithm can properly adjust the spatially varying “local” Fourier coef?cients in favor of the ?nal yield. Three methods, including cascaded single-period (C1P) structure, quasi-periodic optical superlattice (QPOS), and hyper?ne aperiodic optical superlattice (HAOS) optimized by GID, are numerically and experimentally investigated under the platform of third-harmonic generation (THG). It shows that the THG ef?ciency of HAOS + GID can exceed the record achieved by C1P structure by 33%. This method is applicable to general wavelength converters involving with multiple coupled nonlinear processes.
关键词： Optical wavelength conversion,optimization methods,nonlinear optical device,optical harmonic generation
更新于2025-09-12 10:27:22