Context analysis in energy resource management residential buildings

This paper presents a context analysis methodology to improve the management of residential energy resources by making the decision making process adaptive to different contexts. A context analysis model is proposed and described, using a clustering process to group similar situations. Several clustering quality assessment indices, which support the decisions on how many clusters should be created in each run, are also considered, namely: the Calinski Harabasz, Davies Bouldin, Gap Value and Silhouette. Results show that the application of the proposed model allows to identify different contexts by finding patterns of devices' use and also to compare different optimal k criteria. The data used in this case study represents the energy consumption of a generic home during one year (2014) and features the measurements of several devices' consumption as well as of several contextual variables. The proposed method enhances the energy resource management through adaptation to different contexts.The present work was done and funded in the scope of the following projects: European Union's Horizon 2020 research and innovation programme, under the Marie Sklodowska-Curie grant agreement No 703689 (project ADAPT); EUREKA - ITEA2 Project M2MGrids (ITEA-13011), Project SIMOCE (ANI|P2020 17690), and has received funding from FEDER Funds through COMPETE program and from National Funds through FCT under the project UID/EEA/00760/2013info:eu-repo/semantics/publishedVersio

The formation of satellite galaxies and their associated black holes

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Prognostics and health management of light emitting diodes

Prognostics is an engineering process of diagnosing, predicting the remaining useful life and estimating the reliability of systems and products. Prognostics and Health Management (PHM) has emerged in the last decade as one of the most efficient approaches in failure prevention, reliability estimation and remaining useful life predictions of various engineering systems and products. Light Emitting Diodes (LEDs) are optoelectronic micro-devices that are now replacing traditional incandescent and fluorescent lighting, as they have many advantages including higher reliability, greater energy efficiency, long life time and faster switching speed. Even though LEDs have high reliability and long life time, manufacturers and lighting systems designers still need to assess the reliability of LED lighting systems and the failures in the LED. This research provides both experimental and theoretical results that demonstrate the use of prognostics and health monitoring techniques for high power LEDs subjected to harsh operating conditions. Data driven, model driven and fusion prognostics approaches are developed to monitor and identify LED failures, based on the requirement for the light output power. The approaches adopted in this work are validated and can be used to assess the life of an LED lighting system after their deployment based on the power of the light output emitted. The data driven techniques are only based on monitoring selected operational and performance indicators using sensors whereas the model driven technique is based on sensor data as well as on a developed empirical model. Fusion approach is also developed using the data driven and the model driven approaches to the LED. Real-time implementation of developed approaches are also investigated and discussed

The optimal thermo-optical properties and energy saving potential of adaptive glazing technologies

The development of dynamic building envelope technologies, which adapt to changing outdoor and indoor environments, is considered a crucial step towards the achievement of the nearly Zero Energy Building target. It is currently not possible to evaluate the energy saving potential of innovative adaptive transparent building envelopes in an accurate manner. This creates difficulties in selecting between competing technologies and is a barrier to systematic development of these innovative technologies. The main aim of this work is to develop a method for devising optimal adaptive glazing properties and to evaluate the energy saving potential resulting from the adoption of such a technology. The method makes use of an inverse performance-oriented approach, to minimize the total primary energy use of a building. It is applied to multiple case studies (office reference room with 4 different cardinal orientations and in three different temperate climates) in order to evaluate and optimise the performance of adaptive glazing as it responds to changing boundary conditions on a monthly and daily basis. A frequency analysis on the set of optimised adaptive properties is subsequently performed to identify salient features of ideal adaptive glazing. The results show that high energy savings are achievable by adapting the transparent part of the building envelope alone, the largest component being the cooling energy demand. As expected, the energy savings are highly sensitive to: the time scale of the adaptive mechanisms; the capability of the façade to adapt to the outdoor climatic condition; the difference between outdoor climatic condition and the comfort range. Moreover important features of the optimal thermo-optical properties are identified. Of these, one of the most important findings is that a unique optimised technology, varying its thermo-optical properties between a limited number of states could be effective in different climates and orientations.The present work has been developed in the framework of a PhD research project. The authors are grateful to EPSRC and Wintech Ltd. for funding the PhD. The authors are also grateful to the National Natural Science Foundation of China (No. 51408427) for their support.This is the final published version of the article. It was originally published in Applied Energy (Favoino F, Overend M, Jin Q, Applied Energy, 2015, 156, 1-15, doi:10.1016/j.apenergy.2015.05.065). The final version is available at http://dx.doi.org/10.1016/j.apenergy.2015.05.06

New generation light emitting diodes:fundamentals and applications

Light emitting diodes (LEDs) have made tremendous progress in last 15 years andhave reached to a point where they are reinventing and redefining artificial lighting.The efficiency and better control over light quality parameters have been the keyattributes of LEDs that makes them better than the existing lighting solutions.Nevertheless, in their own realm they suffer from decrease in efficiency at highercurrents, i.e. the “efficiency droop” phenomenon. Thus, a better understandingof the mechanisms leading to droop is of utmost importance. Moreover, the fullpotential in terms of light quality, i.e. colour rendering index (CRI) and correlatedcolour temperature (CCT) that can be offered by these devices can be furtherimproved with existing or alternative schemes and device configurations.In this thesis, a novel phosphor covered approach is investigated towards improvingthe CRI for indoor lighting applications. A monolithic di-chromatic LEDemitting at blue and cyan wavelengths is used to pump a green-red phosphor mixtureand a warm (CCT ∼ 3400 K) white light with a superior CRI of 98.6 is achieved.An alternate phosphor free solution to achieve warm white light emission is alsostudied. These monolithic di-chromatic QW devices emitting at blue and greenwavelengths under electrical pumping demonstrated tuneable emission from cool(CCT ∼ 22000 k) to warm (CCT ∼ 5500 K) white light. A maximum CRI of 67,which is the highest value demonstrated for such devices till date to the best of myknowledge, is also achieved.On the subject of efficiency of LEDs, temperature dependence of LEE andIQE of commercial InGaN/GaN based blue LED is studied in light of a step-wiseprocessing procedure based on the ABC-model to determine these quantities. Adecrease in both IQE and LEE with temperature is noted. On the other hand,efficiency decrease in the investigated AlGaInP based red LEDs under pulsed currentshows a shift in the onset of efficiency decrease towards higher current values withdecreasing pulse width with < 1% duty cycle. For sub-nanosecond pulses a linearrelation between applied peak current and peak output power is obtained. Theseobservations indicate device self-heatin

Painting with Turbulence

Inspired by a study that identified a strong similarity between Vincent van Gogh\u27s and Jackson Pollock\u27s painting techniques, this thesis explores the interplay between science and art, specifically the unpredictable behaviors in turbulent flows and aesthetic concepts in painting. It utilizes data from a GPU-based air flow simulation, and presents a framework for artists to visualize the chaotic property changes in turbulent flows and create paintings with turbulence data. While the creation of individual brushstrokes is procedural and driven by simulation, artists are able to exercise their aesthetic judgments at various stages during a painting creation. A short animation demonstrates the potential results from this framework