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The integration of smart grid technologies in interconnected power system networks presents multiple challenges for the power industry and the scientific community. To address these challenges, researchers are creating new methods for the validation of: control, interoperability, reliability of Internet of Things systems, distributed energy resources, modern power equipment for applications covering power system stability, operation, control, and cybersecurity. Novel methods for laboratory testing of electrical power systems incorporate novel simulation techniques spanning real-time simulation, Power Hardware-in-the-Loop, Controller Hardware-in-the-Loop, Power System-in-the-Loop, and co-simulation technologies. These methods directly support the acceleration of electrical systems and power electronics component research by validating technological solutions in high-fidelity environments. In this paper, members of the Survey of Smart Grid International Research Facility Network task on Advanced Laboratory Testing Methods present a review of methods, test procedures, studies, and experiences employing advanced laboratory techniques for validation of range of research and development prototypes and novel power system solutions.

The integration of smart grid technologies in interconnected power system networks presents multiple challenges for the power industry and the scientific community. To address these challenges, researchers are creating new methods for the validation of: control, interoperability, reliability of Internet of Things systems, distributed energy resources, modern power equipment for applications covering power system stability, operation, control, and cybersecurity. Novel methods for laboratory testing of electrical power systems incorporate novel simulation techniques spanning real-time simulation, Power Hardware-in-the-Loop, Controller Hardware-in-the-Loop, Power System-in-the-Loop, and co-simulation technologies. These methods directly support the acceleration of electrical systems and power electronics component research by validating technological solutions in high-fidelity environments. In this paper, members of the Survey of Smart Grid International Research Facility Network task on Advanced Laboratory Testing Methods present a review of methods, test procedures, studies, and experiences employing advanced laboratory techniques for validation of range of research and development prototypes and novel power system solutions.

Piezoelectricity is a well-established property of biological materials, yet its functional role has remained unclear. Here, a mechanical effect of piezoelectric domains resulting from collagen fibril organisation is demonstrated, and its role in tissue function and application to material design is described. Using a combination of scanning probe and nonlinear optical microscopy, a hierarchical structuring of piezoelectric domains in collagen-rich tissues is observed, and their mechanical effects are explored in silico. Local electrostatic attraction and repulsion due to shear piezoelectricity in these domains modulate fibril interactions from the tens of nanometre (single fibril interactions) to the tens of micron (fibre interactions) level, analogous to modulated friction effects. The manipulation of domain size and organisation thus provides a capacity to tune energy storage, dissipation, stiffness, and damage resistance.

We report the implementation of fast Interferometric Second Harmonic Generation (I-SHG) microscopy to study the polarity of non-centrosymmetric structures in biological tissues. Using a sample quartz plate, we calibrate the spatially varying phase shift introduced by the laser scanning system. Compensating this phase shift allows us to retrieve the correct phase distribution in periodically poled lithium niobate, used as a model sample. Finally, we used fast interferometric second harmonic generation microscopy to acquire phase images in tendon. Our results show that the method exposed here, using a laser scanning system, allows to recover the polarity of collagen fibrils, similarly to standard I-SHG (using a sample scanning system), but with an imaging time about 40 times shorter. OCIS codes: (180.4315) Nonlinear microscopy, (190.2620) Harmonic generation and mixing, (170.6935) Tissue characterization, (190.4180) Multiphoton processes, (190.4710) Optical nonlinearities in organic materials

La microscopie optique non linéaire est un domaine qui a beaucoup évolué dans les derniers 25 ans. Ses applications en biologie pour l’étude des tissus sont nombreuses. Dans ce domaine, la microscopie de génération de seconde harmonique (GSH) est une technique d’imagerie qui se distingue des autres par son mécanisme de contraste unique, qui permet d’imager les structures non centrosymétriques comme le collagène des tissus conjonctifs, la myosine des tissus musculaires et certains cristaux optiques non linéaires. Toutefois, la microscopie GSH ne mesure que l’irradiance du signal GSH et sa phase est perdue. Cela pose problème puisque la phase du signal GSH contient de l’information sur l’orientation des molécules non centrosymétriques dans la zone imagée. Il faut donc trouver un moyen de mesurer la phase du signal GSH pour améliorer notre interprétation des images GSH dans les tissus biologiques. Cela est possible en combinant l’interférométrie et la microscopie GSH. L’objectif de ce projet est donc de construire un microscope GSH interférométrique pour mesurer la phase relative du signal GSH dans les tissus biologiques et utiliser ces nouveaux résultats pour faire une meilleure interprétation des images obtenues en microscopie GSH dans ceux-ci. Cette thèse présente une revue historique de la microscopie, de l’optique non-linéaire et de la microscopie optique non-linéaire. La théorie de la génération de seconde harmonique y est détaillée, dans un contexte de microscopie. La structure des tissus musculaires et des tissus conjonctifs de collagène y est résumée, en mettant l’emphase sur leurs propriétés optiques non linéaires. L’histoire et la théorie de la microscopie GSH interférométrique y sont également abordées. La conversion d’un montage en microscope GSH interférométrique et le protocole à suivre pour s’en servir y sont expliqués. Finalement, les résultats de la microscopie GSH interférométrique dans un cristal de niobate de lithium périodiquement orienté (PPLN)

We implemented for the first time Interferometric SHG microscopy, using femtosecond pulses, to image the relative fibrils polarity in cartilage and show that SHG intensity depends on the local ratio of fibrils with opposite polarities.

In this work, we report the implementation of interferometric second harmonic generation (SHG) microscopy with femtosecond pulses. As a proof of concept, we imaged the phase distribution of SHG signal from the complex collagen architecture of juvenile equine growth cartilage. The results are analyzed in respect to numerical simulations to extract the relative orientation of collagen fibrils within the tissue. Our results reveal large domains of constant phase together with regions of quasi-random phase, which are correlated to respectively high- and low-intensity regions in the standard SHG images. A comparison with polarization-resolved SHG highlights the crucial role of relative fibril polarity in determining the SHG signal intensity. Indeed, it appears that even a well-organized noncentrosymmetric structure emits low SHG signal intensity if it has no predominant local polarity. This work illustrates how the complex architecture of noncentrosymmetric scatterers at the nanoscale governs the coherent building of SHG signal within the focal volume and is a key advance toward a complete understanding of the structural origin of SHG signals from tissues.

We image the relative orientation of organized groups of noncentrosymmetric molecules (like collagen or myosin) at the micron scale in biological tissues by combining interferometry and Second Harmonic Generation (SHG) microscopy.