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The luminescent solar concentrator has the potential of widespread use as a generator of electricity from sunlight well-suited for use in the urban environment owing to its adaptability in shape and coloration. The device performance is heavily dependent on the ability to transport light long distances to the edges. A common organic luminophore used in the device is based on a perylene core. In this work, we describe an overlooked effect of UV illumination on the appearance and efficiency of these devices. An additional absorption peak appears upon polymerization under intense UV in nitrogen atmosphere which significantly reduces the edge emissions from the device. The additional absorbance peak disappears after exposure to air, indicating the presence of a radical anion being formed during the UV light exposure. This suggests newly-produced LSC devices should be allowed to stand a period of time under ambient conditions before their performance characteristics are determined, which could have implications in potential future commercialization of the technology.

Electrical energy production from renewable energy sources and electrification of consumer energy demand are developments in the ongoing energy transition. These developments urge the demand for flexibility in low voltage distribution networks, on the one hand caused by the intermittency of renewable energy sources, and on the other hand by the high power demand of battery electric vehicles and heat pumps. One of the foremost ways to create flexibility is by using energy storage systems. This paper proposes a method to first optimize the siting, power and capacity rating, technology, and operation of energy storage systems based on the technical and economic value. Secondly the method can be used to make cost- and time-based network planning decisions between network upgrades and network upgrade deferral by energy storage systems. To demonstrate the proposed method, study cases are analyzed of five low voltage distribution networks with different penetrations of photovoltaics, heat pumps and battery electric vehicles. The optimal energy storage systems in the study cases are: flow batteries sited at over 50% of the cable length with a high capacity rating per euro. With the current state of energy storage system development, network upgrade deferral is up to 61% cheaper than network upgrades in the study cases. The energy storage systems can offer additional value by reducing the peak loading of the medium voltage grid which is not taken into account in this research.

Understanding how the deformation history affects the retraction dynamics of viscoelastic liquid films can provide a tool to design materials. In this paper, we investigate the stretching and retraction of circular viscoelastic liquid films through finite element numerical simulations. We consider a discoid domain made of a viscoelastic liquid. Its central hole is first ‘closed’ and then released, being left free to open under the effect of inertial, surface, viscous, and elastic forces. We perform a parametric study of film retraction, aiming at understanding the effects of the physical and operating parameters on it. In particular, we consider different viscoelastic constitutive equations, namely, Oldroyd-B, Giesekus (Gsk), and Phan Thien-Tanner (PTT) models, and different values of the film initial thickness. For each liquid and geometry, we investigate the effects of the film stretching rate and of liquid inertia, elasticity, and flow-dependent viscosity on the dynamics of the hole opening.