Using detailed data from garment factories in Bangalore, India, we estimate large, negative impacts of temperature on productive efficiency (actual over target output). The introduction of LED lighting, which emits less heat than standard lighting, attenuates the temperatureproductivity gradient by 75 percent. Our estimates suggest that productivity returns to LEDs are more than four times larg...

The digitization of clock has brought us enormous conveniences and the development of the special-purpose clock chip would extend the traditional functions of clock. In this article, we design a new calendar clock based on DS12C887 chip and AT89C52 SCM. The system includes 5 parts: the AT89C52 SCM module, the calendar clock module, the LED display module, serial communication module and the C51...

This paper presents the design of a capacitive power transfer (CPT) system by using the Class-E amplifier approach. The Class-E amplifier approach is chosen to be adopted since it produces high efficiency as close as to 100%, theoretically. Based on the Class-E approach, a design of wireless power transfer system is used to transfer power to a LED lamp. The system has an output around 4.2 watts...

Many of the documents in this series are prepublication/preprint articles, which may subsequently appear (part or whole) in peer reviewed journals and books. In most cases they are draft documents, the purpose of which is to foster discussion and debate, prior to publication elsewhere, whilst ideas are still fresh. Further information about the research programme and other papers in this series...

For the first time photopolymerisation of polymer monoliths has been realised with UV-light emitting diodes (LEDs) as light source and demonstrated with polymethacrylate monoliths created in fused silica capillaries and plastic chips.

This paper shows how to combine a substantial part of the product development cycle of interactive devices into a single, co-ordinated approach. Much can be derived automatically from a suitable specification of the interactive device, and it can be derived automatically. Normal product development has a device specified and built, then has its manuals written, then it is used and tested. At th...

A typical LED (Light Emitting Diode) based lighting system is shown in Fig. 1. It is composed of a power source such as your regular wall outlet or a battery, an LED driver, an LED or banks of LED’s, and a lamp or fixture. An LED driver is an electronic circuit or component that processes power from the source into power usable by the LED’s. The driver regulates and controls the current supplie...

A laboratory experiment was conducted to investigate the performance characteristics of the currently available highpower LEDs under various drive conditions and ambient temperatures. Light output degradation and color shift properties as a function of time were measured for five types of commercial high-flux LEDs, namely, red, green, blue, and white from one manufacturer, and a different high-...

A system for measuring the absolute spectral responsivity of solar cells is described. The system uses higher-powered LED arrays that are coupled to an optical light guide that together provide large area illumination. Two different measurement methods were developed and tested using this measurement apparatus. The first method is an individual LED lock-in technique that can be performed over a...