Microstructural evolution in materials during thermal processing

Copyright © 2012 Joseph K. L. Lai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.This article is made available through the Brunel Open Access Publishing Fund

Uncertainties in the Two-Stage Reception Plate Method for Source Characterisation and Prediction of Structure-Borne Sound Power

To obtain the transmitted structure-borne power from a vibrating machine into a supporting/connected structure, three quantities are required in some form: source activity (either the free velocity or the blocked force), source mobility and receiver mobility. The three quantities can be measured directly, or indirectly using a reception plate method. Whilst direct measurements can be precise, they require extensive data acquisition and processing. The reception plate method is simpler and less precise and therefore yields an engineering grade of accuracy. This paper reports on a collaborative investigation, towards developing an industrial standard for source characterization using the reception plate method. The method yields data as frequency band-averaged values and also as equivalent single values. These simplifications result in uncertainties when obtaining the source quantities and therefore in predictions of the structure-borne sound power in installed conditions. The causes of these uncertainties are considered

Carriage of meticillin-susceptible and -resistant Staphylococcus aureus by medical students in Hong Kong

Letter to the Editorpostprin

Recognition of vehicle registration mark on moving vehicles in an outdoor environment

In this paper, we propose a new method for segmenting vehicle registration plate and recognizing the registration mark on a moving vehicle in an outdoor environment. The algorithm first segments the plate from the vehicle and other complex objects in view, based on the plate color and its dimension. The segmented plate is then corrected in orientation and size, before being matched with a sub-set of templates in the database. The matching adopts a high tolerant scheme allowing characters to have certain degree of shifting, rotation and mis-match. This proves to be an important criterion for successful recognition. Preliminary tests show that this method offers high success rate and high confident level.published_or_final_versio

Intelligent integration of BIPV and load management systems for modern buildings

This paper outlines the basics of load management, and highlights the possibility of maximising the contribution from the Building Integrated Photovoltaic (BIPV) power generation. It will also explain the underlying principles of a dynamic modelling approach and its application in supporting the anticipatory control strategy for load shifting. For many types of building applications, the load profiles are well matched with the BIPV generation profiles such that the BIPV power source is already acting as the peak clipping device. The application of Building Management Systems (BMS) in load shifting should consider the supply from BIPV system. Secondly, due to the thermal mass of the building, there exists time delay in the response of the power requirement of the HVAC system in the building from the solar radiation data. The BIPV system, on the contrary, is responding almost instantaneously to the solar irradiance. A dynamic BIPV model could be applied in aiding the prediction of the load profile. This paper will outline these aspects of the BIPV system as a demonstration of its application in BMS.postprintThe 8th Annual Power Symposium, Hong Kong, 19 June 2009

Integration of BIPV systems and load management

This paper outlines the basics of load management, and highlights the possibility of maximising the contribution from the Building Integrated Photovoltaic (BIPV) power generation. It will also explain the underlying principles of a dynamic modelling approach and its application in supporting the anticipatory control strategy for load shifting. For many types of building applications, the load profiles are well matched with the BIPV generation profiles such that the BIPV power source is already acting as the peak clipping device. The application of Building Management Systems (BMS) in load shifting should consider the supply from BIPV system. Secondly, due to the thermal mass of the building, there exists time delay in the response of the power requirement of the HVAC system in the building from the solar radiation data. The BIPV system, on the contrary, is responding almost instantaneously to the solar irradiance. A dynamic BIPV model could be applied in aiding the prediction of the load profile. This paper will outline these aspects of the dynamic model developed as a demonstration of its application.postprintThe International Conference on Electrical Engineering 2009

On the color stability of phosphor-converted white LEDs under DC, PWM, and bilevel drive

Most commercial white LEDs are made from nitride-based blue LEDs coated with yttrium aluminium garnet phosphor, which produce spectra that shift in opposite directions under the influences of drive current and junction temperature changes. This property gives rise to different emitted spectra, hence chromaticity properties, when the LED is driven/dimmed by different current waveforms. By using a commercial white LED sample, LUXEON K2, the effects of drive current and junction temperature on the changes of chromaticity coordinates are studied experimentally. The impact of dc, pulse width modulation (PWM), and bilevel current waveform is discussed through a graphical analysis, followed by experimental verification. It is proven that dc offers the best color stability over dimming due to the counteracting influences of drive current and junction temperature variations, whereas an LED constantly suffers from noneliminable chromaticity changes when driven by the PWM. Theoretical explanations are given to justify these cases, and it is found that, for the case of dc drive, an ideal heat sinks thermal resistance can be selected based on a simple equation to minimize the overall chromaticity change over dimming. This paper provides an in-depth discussion on the relations between the chromaticity properties of phosphor-converted (pc) white LEDs and the driving/dimming methods used. © 2011 IEEE.published_or_final_versio

Distinctive patterns of macrolide-lincosamide-streptogramin resistance phenotypes and determinants amongst Staphylococcus aureus populations in Hong Kong

postprin

Stationary and adaptive color-shift reduction methods based on the bilevel driving technique for phosphor-converted white LEDs

The bilevel driving technique has realized a 2-D control of the luminosity and emitted color of white LEDs with duty cycle and forward current levels. Unfortunately, various combinations of these dimming control parameters can lead to significant changes in junction temperature, which further modify the luminosity and emitted color of LEDs. In this paper, the theoretical aspects of these complex interactions and the impact of bilevel drive on the color-shift properties of white LEDs are discussed in detail by using a mathematical color-shift model. Two color-shift reduction methods are proposed based on the insights obtained from this model. This study shows that a heat sinks thermal resistance that minimizes the overall color shift over dimming can be uniquely determined from the knowledge of some measurable LED parameters, and gives rise to a global minimum color shift. If such a thermal resistance cannot be realized due to practical limitations, the second method that utilizes an adaptive change of forward current levels over dimming can be adopted. Based on their nature, these methods are classified as stationary and adaptive methods, respectively. Their validity is supported by experimental measurements on a commercial white LED. © 2011 IEEE.published_or_final_versio