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©2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This paper presents a network clustering (NC) method for active distribution networks (ADNs). Following the outage of a section of an ADN, the method identifies and forms an optimum cluster of microgrids within the section. The optimum cluster is determined from a set of candidate microgrid clusters by estimating the following metrics: total power loss, voltage deviations, and minimum load shedding. To compute these metrics, equivalent circuits of the clusters are estimated using measured data provided by phasor measurement units (PMUs). Hence, the proposed NC method determines the optimum microgrid cluster without requiring information about the network’s topology and its components. The proposed method is tested by simulating a study network in a real-time simulator coupled to physical PMUs and a prototype algorithm implementation, also executing in real time. Peer Reviewed

Environmental concerns regarding global warming and ozone depletion urge towards sustainable solutions for satisfying the increasing cooling demand. Adsorption cooling technology could form part of the solution since it can be driven by solar energy and industrial or vehicular waste heat, as well as it employs non ozone-destructive refrigerants. However, its low performance hinders its extensive development and commercialization. The design of the adsorption reactor is crucial for its performance improvement, since its inherent cyclic operation imposes a compromise between the Specific Cooling Power and the Coefficient of Performance. A generalized three-dimensional computational model based on unstructured meshes is presented, capable to simulate all potential geometries. Dynamic conjugate simulations of the packed bed and the heat exchanger allow to study the latter’s influence on the reactor performance. A parametric study of five reactor geometries was conducted, demonstrating quantitatively the strong impact of the solid volume fraction, fin length and fin thickness on the performance. Within the studied range, the Specific Cooling Power is maximized for the highest solid volume fraction and for the lowest fin thickness and fin length. The effect of the adsorbed mass spatial distribution on the desorption phase is discussed. A sensitivity analysis exhibits the importance of the heat transfer coefficient between the two domains. Copper and aluminium are compared as heat exchanger materials, revealing that the former performs more effectively, although the difference is appreciable only for longer fin lengths. The presented numerical model can be employed for improving the design of adsorption packed bed reactors. Peer Reviewed

Large scale mitigation strategies showed to represent promising solutions for enhancing liveability in dense urban contexts. Therefore, most of the researches are focused on assessing the effect of high albedo surfaces and greenery. The paper deals with a numerical and experimental analysis of these evapotranspiration and high-reflectance surfaces in a full scale experimental set-up where more than 20 cubicles are monitored in a Mediterranean continental climate. The experimental set-up itself covers an intermediate inter-building perspective between the lab scale and the real urban contexts, which compromises the possibility to generalize final results. This scale is able to better control geometry of area, but allows real microclimate monitoring and calibration of CFD models. Starting from a validated model, this study simulated alternative scenarios with gradually varying the presence of common mitigation strategies with the scope to evaluate their effect to this aim. Results showed that high albedo solutions best mitigate summer overheating reducing the air temperature, while greenery was more effective in the densest configurations with low albedo envelopes, showing how geometry related variables may play a key role in determining the optima configurations of microclimate mitigation strategies, also important for the best exploitation of renewables in the built environment. © 2019 Elsevier Ltd

This paper deals with the fractional modelling of a DC-DC converter, suitable in solar-powered electrical generation systems, and the design of a fractional controller for the aforementioned switching converter. A new model for PV cells is proposed in order to obtain a linear equation for V-I characteristic via scheduling dependence of temperature and irradiance. Due to the fractional nature of the ultracapacitors this kind of controller gives a suitable and good performance. Peer Reviewed

Does realistic lighting in an immersive virtual reality application enhance presence, where participants feel that they are in the scene and behave correspondingly? Our previous study indicated that presence is more likely with real-time ray tracing compared with ray casting, but we could not separate the effects of overall quality of illumination from the dynamic effects of real-time shadows and reflections. Here we describe an experiment where 20 people experienced a scene rendered with global or local illumination. However, in both conditions there were dynamically changing shadows and reflections. We found that the quality of illumination did not impact presence, so that the earlier result must have been due to dynamic shadows and reflections. However, global illumination resulted in greater plausibility - participants were more likely to respond as if the virtual events were real. We conclude that global illumination does impact the responses of participants and is worth the effort.

Changes in temperature in clays of low permeability typically induce excess porewater pressures. In the context of geothermal piles this effect has typically been overlooked since most installations have occurred in soils with higher values of permeability. A parametric study is presented that solves the governing differential equations one dimensionally in a pile to study the influence of the various parameters: temperature of the fluid, permeability and soil compressibility. A new shaft resistance reduction ratio has been also defined to illustrate the loss of bearing capacity. The study shows that when the value of permeability is 1E-11 m/s or lower, combined with a soil compressibility in excess of 20,000 MPa, the developed excess porewater pressures can potentially reduce the effective stress locally to very low values. The solution applied to the case of the Lambeth College, London, also provides a plausible explanation to the observed loss of shaft friction of the tested pile. Peer Reviewed