Degradation Analysis of Silicone as Encapsulation and Molding Material in High Power LEDs

Applications of LEDs have increased significantly, and increasing outdoor applications are observed. Some outdoor applications require high reliability as their failure can lead to hazardous consequences. Examples are their applications in automotive, street lamp lighting etc. To ensure the reliability of LEDs in outdoor applications, reliability test that include humidity on the LEDs must be done. However, it is found that accelerated life test of LEDs at high humidity level cannot be extrapolated to standard condition of lower humidity as the mechanism of degradation depends critically on humidity level. In fact, the degradation of LEDs in outdoor applications is mainly due to the degradation of their encapsulation and housing materials (or called packaging material as a whole) instead of the semiconductor chip itself. The decrease in lumen is the results of crack and discoloration of the LED packaging material. Detail understanding of the failure physics of the packaging material for LED under humidity is needed for extrapolation performed at accelerated stress condition so that LED luminary reliability can be predicted. This chapter reviews the different types of degradation physics of the packaging material using ab-initio simulation with excellent verification from experiments. The method of extrapolation is therefore derived from the physics-based model after detailed understanding of the degradation physics of LEDs. The model also provides strategy for industry to prolong the usage of LEDs in outdoor applications, either through materials or operating conditions selection

Full Proceedings, 2018

Full conference proceedings for the 2018 International Building Physics Association Conference hosted at Syracuse University

Sustainability in design: now! Challenges and opportunities for design research, education and practice in the XXI century

Copyright @ 2010 Greenleaf PublicationsLeNS project funded by the Asia Link Programme, EuropeAid, European Commission

ENERGY CONSUMPTION OF MOBILE PHONES

Battery consumption in mobile applications development is a very important aspect and has to be considered by all the developers in their applications. This study will present an analysis of different relevant concepts and parameters that may have an impact on energy consumption of Windows Phone applications. This operating system was chosen because limited research related thereto has been conducted, even though there are related studies for Android and iOS operating systems. Furthermore, another reason is the increasing number of Windows Phone users. The objective of this research is to categorise the energy consumption parameters (e.g. use of one thread or several threads for the same output). The result for each group of experiments will be analysed and a rule will be derived. The set of derived rules will serve as a guide for developers who intend to develop energy efficient Windows Phone applications. For each experiment, one application is created for each concept and the results are presented in two ways; a table and a chart. The table presents the duration of the experiment, the battery consumed in the experiment, the expected battery lifetime, and the energy consumption, while the charts display the energy distribution based on the main threads: UI thread, application thread, and network thread

A WEB-BASED ENVIRONMENTAL TOOLKIT TO SUPPORT SMES IN THE IMPLEMENTATION OF AN ENVIRONMENTAL MANAGEMENT SYSTEM

With small and medium sized-enterprises (SMEs) taking up the majority of the global businesses, it is important they act in an environmentally responsible manner. Environmental management systems (EMS) help companies evaluate and improve their environmental impact but they often require human, financial, and temporary resources that not all SMEs can afford. This research encompasses interviews with representatives of two small enterprises in Germany to provide insights into their understanding, and knowledge of an EMS and how they perceive their responsibility towards the environment. Furthermore, it presents a toolkit created especially for small and medium-sized enterprises. It serves as a simplified version of an EMS based on the ISO 14001 standard and is evaluated by target users and appropriate representatives. Some of the findings are: while open to the idea of improving their environmental impact, SMEs do not always feel it is their responsibility to do so; they seem to lack the means to fully implement an EMS. The developed toolkit is considered useful and usable and recommendations are drawn for its future enhancement

Performance measurement in construction research & development: The use of case study research approach

The process of finding solutions to the research problem does not follow a clear sequential approach, but often takes unexpected turns due to the uncertainties of the research process and its outcomes. However, appropriate research design would be able to identify any problems and pitfalls that the researcher may come across during the process. In this regard, consideration of the research philosophy pertaining to the study helps a researcher in choosing the appropriate approach for a study. Not only the philosophical stance, but also the research problem under investigation and its underling circumstances influence the selection of a research approach. Accordingly, this paper discusses the factors that drive the selection of a case study as the research approach with particular reference to the use of single case study to undertake an in depth inquiry regarding the impact of performance measurement towards construction research and development. Further, this paper discusses the incorporation of multi-phase, multi perspective and multi-method approaches within the single case study to build valid theory