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Downward lighting light-emitting diodes require cooling with cylindrical fin heat sinks to be mounted on top and cooled under natural convection air cooling mode. Performance simulation would involve specification of the heat transfer coefficient. Numerous methods are available to simulate the performance of conventional plate fin heat sinks including computational fluid dynamics packages. It would be feasible to perform simulation based on conventional flat plate fin heat sinks. A cylindrical fin heat sinks could be simply treated as a plate fin heat sink, if we imagine it cut open and laid out horizontally. A theoretical model is proposed in this paper. An experimental investigation is conducted here to validate its accuracy. Convective heat transfer coefficients were experimentally determined for a horizontally and vertically inclined bare plate operating under natural and forced air cooling modes. In addition, a vertical plate fin heat sink and a vertical cylindrical fin heat sink under natural convection were investigated. Power inputs were kept from 5 to 40W in order to keep operating temperatures below 100 C. Comparison of the experimental heat transfer coefficients and those obtained from well-known existing Nusselt number correlations show that agreement was poor for the bare plate but satisfactory for the plate and cylindrical fin heat sinks. Although they are within the generally accepted range, it would be advisable for actual measurements to be carried out in order to provide more accurate sizing for thermal measurements. [ABSTRACT FROM AUTHOR]

Solar energy is a renewable energy heat source freely and widely available everywhere throughout the year. Heat pipes are very effective and passive heat transfer devices. A solar heat pipe collector performs well at high temperatures. Thermoelectricity could be utilized for power generation and provide cooling and heating. The combination of a solar heat pipe collector with thermoelectric modules could provide a very useful device for simultaneous power generation and hot water heating. Such hybrid systems could offer small, mobile, transportable and off-grid power and heating systems for small-scale industry or domestic applications. This paper reviews some of the works conducted on the solar/heat pipe/thermoelectric hybrid system. [ABSTRACT FROM AUTHOR]

Heat pipe heat exchangers could be employed as run-around coils in air conditioning systems for enhanced dehumidification and cooling. This article reviews some of the works conducted on the cooling and dehumidification aspects in various air conditioning systems. They have been proved to be effective in enhancing dehumidification and reducing air conditioning costs especially in hot and humid tropical countries. [ABSTRACT FROM AUTHOR]

A conventional natural convection flat plate solar collector needs to be placed at an incline to the horizontal and exposed to the sun in order for the solar hot water heater system to work. This arrangement is satisfactory where there is ample roof top space to locate the collector and storage tank. In a high-rise apartment, space is at a premium and also the hot-water recticulation requires long lengths of piping to distribute the hot water supply to the individual apartment. Most every modern high-rise apartment has a balcony facing outward from the wall structure. Balcony-type solar water heaters (SWHs) are catching up fast in China. Their performance would depend on collector and storage tank designs and sizes, weather conditions (solar radiation intensity and ambient temperature) and direction in which the balconies are facing. This article compares the outdoor performance of two SWH systems incorporating the evacuated glass U-tube solar collectors operating under natural convection. The panels were tested in both the vertical and inclined positions using the same tank but at different times of the year. It was found that the inclined panel system performed better than the system with the vertical panel system. [ABSTRACT FROM AUTHOR]

Flexible poly(p-phenylene vinylene) organic light-emitting diodes (OLEDs) with top-emitting architecture were developed on metal-sandwiched polyethylene terephthalate (PET) substrates. Commercial aluminum-laminated PET (Al-PET) was adopted as initial substrates. Different kinds of metal layers (silver and nickel) were then deposited on Al-PET foil to form metal-sandwiched plastic substrates and also to serve as anodes for the top emitting OLEDs. Interface modification was employed to enhance carrier injection from the metal anodes to the polymeric organic stack. Semitransparent top cathodes were used for the flexible top-emitting diodes. The performance of these OLEDs was characterized and compared among different metal anodes. The flexible top-emitting OLEDs on metal-sandwiched PET foil can be bent to a substantial degree without breaking. Moreover, increased contrast ratio of OLEDs can be achieved with specific anodes due to lower reflectance of nickel material. [ABSTRACT FROM AUTHOR]

Sound measurement, an essential component of any scientific discipline, remains a particular problem in pain research. The measurement of pain intensity, for example, is a difficult and often a subjective undertaking. This is of little surprise to clinicians and researchers, because it is well recognised that pain intensity, like other sensations and perceptions, is a private experience that displays considerable variability both across patients and within a patient across time. Nonetheless, pain measurement and discerning factors that may affect its measurement are important for diagnosis and to determine the effectiveness of treatment interventions. This article reviews the basic concepts, roles, instruments used, and factors affecting pain measurement. A variety of the most commonly used pain measurement instruments are evaluated for their advantages and disadvantages. The article aims to assist clinicians and researchers to select the pain measurement instruments that best serve their purposes. [ABSTRACT FROM AUTHOR]