Recherche

Robyr Jean-Luc

Professeur HES associé

Compétences principales

Professeur HES associé

Téléphone: +41 26 429 68 44

Bureau: HEIA_D10.11

Haute école d'ingénierie et d'architecture de Fribourg
Boulevard de Pérolles 80, 1700 Fribourg, CH

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2021

High-frequency guided wave propagation and scattering in silicon wafers

Scientifique ArODES

Robyr Jean-Luc, Mathieu Simon, Masserey Bernard, Fromme Paul

Journal of Nondestructive Evaluation, Diagnostics and Prognostics of Engineering Systems, 2021, vol. 4, no. 4, article no. 041007

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Résumé:

Thin monocrystalline silicon wafers are employed for the manufacturing of solar cells with high conversion efficiency. Micro-cracks can be induced by the wafer cutting process, leading to breakage of the fragile wafers. High-frequency guided waves allow for the monitoring of wafers and detection and characterization of surface defects. The material anisotropy of the monocrystalline silicon leads to variations of the guided wave characteristics, depending on the guided wave mode and propagation direction relative to the crystal orientation. Selective excitation of the first antisymmetric A0 wave mode at 5 MHz center frequency was achieved experimentally using a custom-made wedge transducer. Strong wave pulses with limited beam skewing and widening were measured using noncontact laser interferometer measurements. This allowed the accurate characterization of the Lamb wave propagation and scattering at small artificial surface defects with a size of less than 100 µm. The surface extent of the defects of varying size was characterized using an optical microscope. The scattered guided wave field was evaluated, and characteristic parameters were extracted and correlated with the defect size, allowing in principle detection of small defects. Further investigations are required to explain the systematic asymmetry of the guided wave field in the vicinity of the indents.

2020

Modeling the vertical motion of a zero pressure gas balloon

Scientifique ArODES

Robyr Jean-Luc, Bourquin Vincent, Goetschi Damien, Schroeter Nicolas, Baltensperger Richard

Journal of Aircraft, 2020, vol. 57, no. 5

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2018

Genetic algorithm optimization of the economical, ecological and self-consumption impact of the energy production of a single building

Scientifique ArODES

Favre Ludovic, Schafer Thibaut M., Robyr Jean-Luc, Niederhäuser Elena-Lavinia

Energy and Power Engineering, 2018, vol. 12, no. 9

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Résumé:

This paper presents an optimization method based on genetic algorithm for the energy management inside buildings developed in the frame of the project Smart Living Lab (SLL) in Fribourg (Switzerland). This algorithm optimizes the interaction between renewable energy production, storage systems and energy consumers. In comparison with standard algorithms, the innovative aspect of this project is the extension of the smart regulation over three simultaneous criteria: the energy self-consumption, the decrease of greenhouse gas emissions and operating costs. The genetic algorithm approach was chosen due to the large quantity of optimization variables and the non-linearity of the optimization function. The optimization process includes also real time data of the building as well as weather forecast and users habits. This information is used by a physical model of the building energy resources to predict the future energy production and needs, to select the best energetic strategy, to combine production or storage of energy in order to guarantee the demand of electrical and thermal energy. The principle of operation of the algorithm as well as typical output example of the algorithm is presented.

Lamb wave propagation in monocrystalline silicon wafers

Scientifique ArODES

Fromme Paul, Pizzolato Marco, Robyr Jean-Luc, Masserey Bernard

The Journal of the Acoustical Society of America, 2018, 143, 1, pp. 287-295

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Résumé:

Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. Guided ultrasonic waves offer the potential to efficiently detect microcracks in the thin wafers. Previous studies of ultrasonic wave propagation in silicon focused on effects of material anisotropy on bulk ultrasonic waves, but the dependence of the wave propagation characteristics on the material anisotropy is not well understood for Lamb waves. The phase slowness and beam skewing of the two fundamental Lamb wave modes A0 and S0 were investigated. Experimental measurements using contact wedge transducer excitation and laser measurement were conducted. Good agreement was found between the theoretically calculated angular dependency of the phase slowness and measurements for different propagation directions relative to the crystal orientation. Significant wave skew and beam widening was observed experimentally due to the anisotropy, especially for the S0 mode. Explicit finite element simulations were conducted to visualize and quantify the guided wave beam skew. Good agreement was found for the A0 mode, but a systematic discrepancy was observed for the S0 mode. These effects need to be considered for the non-destructive testing of wafers using guided waves.

2018

Improvement of the environmental impact of the global energy management of buildings by genetic algorithm optimization

Conference ArODES

Jean-Luc Robyr, Elena-Lavinia Niederhäuser

Proceedings of 5th International Conference on Electric Power and Energy Conversion Systems (EPECS), 23-25 April 2018, Kitakyushu, Japan

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Résumé:

The reduction of the environmental impact of buildings through better energy management could play a significant role in achieving nowadays greenhouse gas emission reduction targets. In this context and following this purpose, we developed a regulation algorithm to manage the global energy resources of buildings. The control approach optimizes the coupling between local renewable energy production systems (e.g. thermal and photovoltaic solar panels) and energy storage devices (e.g. cold and hot water storage tanks, electrical battery). The innovative aspect of this project compared to standard regulations is the simultaneous optimization of three criteria: the consumption of external energy resources, the costs and the ecological impact. In this paper we present and analyse the implementation of this regulation based on the ecological criterion. A genetic optimization is performed according to a score function evaluating the ecological impact based on the CO2 equivalent production. In order to improve the strategy, the regulation predicts the future energy demand and production. The genetic algorithm approach is used due to the large amount of optimization variables and the non-linearity of the score function. This genetic optimization algorithm uses real time data like building physical data (e.g. internal temperature) and prediction based on the user’s habits and weather information to define the best energy strategy. It insures the electrical and thermal energy demand while optimizing the ecological criterion. To demonstrate the algorithm performances, the regulation was implemented and tested with an independent simulation environment. The ecological impact of the genetic algorithm regulation over one week is then compared to the greenhouse gas emission from a standard regulation. With this setting, a reduction of 29 kg equivalent CO2 was realized, which shows the enormous potential of the new regulation approach.

Intelligent algorithm for energy, both thermal and electrical, economic and ecological optimization for a smart building

Conference ArODES

Jean-Luc Robyr, Elena-Lavinia Niederhäuser

Proceedings of ENERGYCON 2018 IEEE International Energy Conference, 3-7 June 2018, Cyprus

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Résumé:

In the frame of a research project conducted at the Smart Living Lab (SLL), a research center dedicated to the building of the future, this paper presents an algorithm that optimizes the coupling of local renewable energy production systems with energy storage devices and the different consumers both at the level of the building and of its peripherals. The main goal is to improve the energy self-sufficiency of a building by combining three aspects in the same time. The optimization criteria are the renewable energy based independence and the ecological (greenhouses gases emissions) and economical (costs) aspects. The underlying approach to perform the global optimization is first presented, explaining how the algorithm combines and optimizes these three criteria. For this purpose, it takes into account the current value of the state variables (temperature, etc.) and the forecasts future values. These data represent the input of a genetic optimization algorithm that computes the best use of each element of the production and storage systems to ensure the electrical and thermal energy demand. The choice of genetic algorithm is motivated by the large amount of optimization variables and the non-linearity of the score function. The typical computation time for this kind of optimization is short enough to allow a real time regulation. The composition of the energy production and storage is flexible allowing to integrate many technologies types, thus increasing its portability.

Convergence of multi-criteria optimization of a building energetic resources by genetic algorithm

Conference ArODES

Jean-Luc Robyr, Elena-Lavinia Niederhäuser

Proceedings of 2018 International Conference on Smart Grid and Clean Energy Technologies (ICSGCE), 29 May-1 June 2018, Kajang, Malaysia

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Résumé:

Better energy management systems for buildings could play a significant role in achieving nowadays greenhouse gas emission reduction targets. In this context, a regulation algorithm to manage the interaction between local renewable energy production, local energy storage devices and an external power source (power grid) was developed. The innovative aspect of this project compared to existing solution is the simultaneous optimization following three criteria: the external energy consumption, the cost and ecological impacts. The new optimization algorithm is based on the genetic algorithm method due to the large solutions space and the non-linearity of the optimization function. This method is coupled to a physical model of the building under study (a typical dwelling house) and its energetic network (production and storage). In addition, weather forecast data as well as data on the user habits are integrated. This paper shows the results of the optimization algorithm applied to a set of realistic values. The genetic algorithm is compared to a pure random optimization approach and their optimization efficiencies are analyzed. Finally, the best strategy obtained by the genetic algorithm for a realistic computation time of several minutes is presented and investigated in detailed. This results shows that the genetic algorithm can perform a 48 hours simulation with no outcome costs, a global production of 4.3 kWh of energy and a greenhouse gas production of -1.4 kg of CO2 equivalent, whereas the consumption of the building costs +1.3 CHF, consumes 7.0 kWh of energy and generates +1.3 kg of CO2 equivalent.

Guided ultrasonic wave beam skew in silicon wafers

Conference ArODES

Jean-Luc Robyr, Bernard Masserey

Proceedings of 44th annual review of progress in quantitative nondestructive evaluation, vol. 37, Provo, Utah, USA, 16-21 July 2017

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Silicon wafer defect detection using high frequency guided waves

Conference ArODES

Jean-Luc Robyr, Bernard Masserey

Proceedings of SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring: Health Monitoring of Structural and Biological Systems XII, Denver, Colorado, United States, 4-8 March 2018

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Résumé:

In the photovoltaic industry monocrystalline silicon wafers are employed for the manufacture of solar panels with high conversion efficiency. The cutting process induces micro-cracks on the thin wafer surface. High frequency guided ultrasonic waves are considered for the structural monitoring of the wafers and the nondestructive characterization of the micro-cracks. The material anisotropy of the monocrystalline silicon leads to variations of the wave characteristics depending on the propagation direction relative to the crystal orientation. In non-principal directions of the crystal, wave beam skewing occurs. Selective excitation of the fundamental Lamb wave modes was achieved using a custom-made angle beam transducer and holder to achieve a controlled contact pressure. The out-of-plane component of the guided wave propagation was measured using a noncontact laser interferometer. Artificial defects were introduced in the wafers using a micro indenter with varying loads. The defects were characterized from microscopy images to measure the indent size and combined crack length. The scattering of the A0 Lamb wave mode was measured experimentally and the characteristics of the scattered wave field were correlated to the defect size. The detection sensitivity is discussed.

2017

High frequency guided wave propagation in monocrystalline silicon wafers

Conference ArODES

Jean-Luc Robyr, Bernard Masserey

Health Monitoring of Structural and Biological Systems 2017 ; SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 25-29 March 2017, Portland, Oregon, United States

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Résumé:

Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. The cutting process can introduce micro-cracks in the thin wafers and lead to varying thickness. High frequency guided ultrasonic waves are considered for the structural monitoring of the wafers. The anisotropy of the monocrystalline silicon leads to variations of the wave characteristics, depending on the propagation direction relative to the crystal orientation. Full three-dimensional Finite Element simulations of the guided wave propagation were conducted to visualize and quantify these effects for a line source. The phase velocity (slowness) and skew angle of the two fundamental Lamb wave modes (first anti-symmetric mode A0 and first symmetric mode S0) for varying propagation directions relative to the crystal orientation were measured experimentally. Selective mode excitation was achieved using a contact piezoelectric transducer with a custom-made wedge and holder to achieve a controlled contact pressure. The out-of-plane component of the guided wave propagation was measured using a noncontact laser interferometer. Good agreement was found with the simulation results and theoretical predictions based on nominal material properties of the silicon wafer.

Réalisations

Recherche

Robyr Jean-Luc

Professeur HES associé

Compétences principales

Programmation python

Modélisation physique

Traitement de données

Optique de précision

Professeur HES associé