Optical properties of some surfaces for solar energy application

The preThe present work is a study of the optical properties of some surfaces, in order to determine their applications in solar energy utilisation. An attempt has been made to investigate and measure the optical properties of two systems of surface moderately selective surfaces like thermally grown oxide of titanium, titanium oxide en aluminium and thermally grown oxides of stainless steel; and, selective surfaces of five different coloured stainless at (INCO surfaces) and of black nickel foil. A calorimetric instrument based on the steady state method for measuring directly the total emittance has been designed. Chapter 1 is an introductory survey of selective surface. It also includes a brief review of various preparation techniques in use since 1955. Chapter 2 investigates the theory of selective surfaces, defining their optical properties and their figures of merit. It also outlines the method of computing the optical properties (i.e. absorptance, a, and emittance, a) which have been adopted for the present work. Chapter 3 describes the measuring technique and the modes of operation of the equipment used in the experimental work carried out. Chapter 4 gives the results of the experimental work to measure the optical properties, the life testing and chemical composition of the surfaces under study. Chapter 5 deals with the experimentation leading to the design of a calorimetric instrument for measuring the total emmitance directly. Chapter 6 presents concluding remarks about the outcome of the present work and some suggestions for further work. sent work is a study of the optical properties of some surfaces, in order to determine their applications in solar energy utilisation. An attempt has been made to investigate and measure the optical properties of two systems of surface moderately selective surfaces like thermally grown oxide of titanium, titanium oxide en aluminium and thermally grown oxides of stainless steel; and, selective surfaces of five different coloured stainless at (INCO surfaces) and of black nickel foil. A calorimetric instrument based on the steady state method for measuring directly the total emittance has been designed. Chapter 1 is an introductory survey of selective surface. It also includes a brief review of various preparation techniques in use since 1955. Chapter 2 investigates the theory of selective surfaces, defining their optical properties and their figures of merit. It also outlines the method of computing the optical properties (i.e. absorptance, a, and emittance, a) which have been adopted for the present work. Chapter 3 describes the measuring technique and the modes of operation of the equipment used in the experimental work carried out. Chapter 4 gives the results of the experimental work to measure the optical properties, the life testing and chemical composition of the surfaces under study. Chapter 5 deals with the experimentation leading to the design of a calorimetric instrument for measuring the total emmitance directly. Chapter 6 presents concluding remarks about the outcome of the present work and some suggestions for further work.

Wear of abrasion resisting materials

The wear behaviour of a series of chromium containing white irons has been investigated under conditions of high stress grinding abrasion using a specimen on track abrasion testing machine. The measured abrasion resistance of the irons has been explained in terms of microstructure and hardness and with respect to the wear damage observed at and beneath abraded surfaces. During abrasion material removal occurred by cracking and detachment from the matrix of eutectic carbides as well as by penetration and micromachining effects of the abrasive grits being crushed at the wearing surface. Under the particular test conditions used martensitic matrix structures gave higher resistance to abrasion than austenitic or pearlitic. However, no simple relationship was found between general hardness or matrix microhardness at wear surfaces and abrasion resistance, and the test yielded pessimistic results for austenitic irons. The fine structures of the 15% Cr and 30% Cr alloys were studied by thin foil transmission electron microscopy. It was found that both the matrix and carbide constituents could be thinned for examination at 100 Kv using conventional dishing followed by ion beam thinning. Flany of the rodlike eutectic N7C3 carbides were seen to consist of clusters of scalier rods with individual 117C3 crystals quite often containing central cores of matrix constituent. 3oth eutectic and secondary N7C3 carbides were found to contain stacking faults on planes normal to the basal plane. In the eutectic carbides in the 30A Cr iron there was evidence of an in-situ PI7C3 C. transition which had taken place during the hardening heat treatment of this alloy. In the as-cast austenitic matrix iron strain induced martensite was produced at the wear surface contributing to work hardening. The significance of these findings have been discussed in relation to wear performance.

A compact, portable and low cost generic interrogation strain sensor system using an embedded VCSEL, detector and fibre Bragg grating

We present a compact, portable and low cost generic interrogation strain sensor system using a fibre Bragg grating configured in transmission mode with a vertical-cavity surface-emitting laser (VCSEL) light source and a GaAs photodetector embedded in a polymer skin. The photocurrent value is read and stored by a microcontroller. In addition, the photocurrent data is sent via Bluetooth to a computer or tablet device that can present the live data in a real time graph. With a matched grating and VCSEL, the system is able to automatically scan and lock the VCSEL to the most sensitive edge of the grating. Commercially available VCSEL and photodetector chips are thinned down to 20 µm and integrated in an ultra-thin flexible optical foil using several thin film deposition steps. A dedicated micro mirror plug is fabricated to couple the driving optoelectronics to the fibre sensors. The resulting optoelectronic package can be embedded in a thin, planar sensing sheet and the host material for this sheet is a flexible and stretchable polymer. The result is a fully embedded fibre sensing system - a photonic skin. Further investigations are currently being carried out to determine the stability and robustness of the embedded optoelectronic components. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

The extent and reasons for compliance failure with oral treatment regimens in haematology outpatients

Focal points: Self-completion questionnaires were used to determine issues with compliance surrounding the use of oral chemotherapy in haematology patients Forty-two patients were identified of which 40 responded over a two-month period Twenty-one respondents (52.5 per cent) indicated that they experienced difficulties in taking their medication Difficulties were not apparently related to the time of dosing; the size of dose units (hydroxyurea) and foil packed agents caused particular difficulties

Mobile app Aston contrast sensitivity test

BACKGROUND: Contrast detection is an important aspect of the assessment of visual function; however, clinical tests evaluate limited spatial frequencies and contrasts. This study validates the accuracy and inter-test repeatability of a swept-frequency near and distance mobile app Aston contrast sensitivity test, which overcomes this limitation compared to traditional charts. METHOD: Twenty subjects wearing their full refractive correction underwent contrast sensitivity testing on the new near application (near app), distance app, CSV-1000 and Pelli-Robson charts with full correction and with vision degraded by 0.8 and 0.2 Bangerter degradation foils. In addition repeated measures using the 0.8 occluding foil were taken. RESULTS: The mobile apps (near more than distance, p = 0.005) recorded a higher contrast sensitivity than printed tests (p < 0.001); however, all charts showed a reduction in measured contrast sensitivity with degradation (p < 0.001) and a similar decrease with increasing spatial frequency (interaction > 0.05). Although the coefficient of repeatability was lowest for the Pelli-Robson charts (0.14 log units), the mobile app charts measured more spatial frequencies, took less time and were more repeatable (near: 0.26 to 0.37 log units; distance: 0.34 to 0.39 log units) than the CSV-1000 (0.30 to 0.93 log units). The duration to complete the CSV-1000 was 124 ± 37 seconds, Pelli-Robson 78 ± 27 seconds, near app 53 ± 15 seconds and distance app 107 ± 36 seconds. CONCLUSIONS: While there were differences between charts in contrast levels measured, the new Aston near and distance apps are valid, repeatable and time-efficient method of assessing contrast sensitivity at multiple spatial frequencies.

A compact, portable and low cost generic interrogation strain sensor system using an embedded VCSEL, detector and fibre Bragg grating

We present a compact, portable and low cost generic interrogation strain sensor system using a fibre Bragg grating configured in transmission mode with a vertical-cavity surface-emitting laser (VCSEL) light source and a GaAs photodetector embedded in a polymer skin. The photocurrent value is read and stored by a microcontroller. In addition, the photocurrent data is sent via Bluetooth to a computer or tablet device that can present the live data in a real time graph. With a matched grating and VCSEL, the system is able to automatically scan and lock the VCSEL to the most sensitive edge of the grating. Commercially available VCSEL and photodetector chips are thinned down to 20 µm and integrated in an ultra-thin flexible optical foil using several thin film deposition steps. A dedicated micro mirror plug is fabricated to couple the driving optoelectronics to the fibre sensors. The resulting optoelectronic package can be embedded in a thin, planar sensing sheet and the host material for this sheet is a flexible and stretchable polymer. The result is a fully embedded fibre sensing system - a photonic skin. Further investigations are currently being carried out to determine the stability and robustness of the embedded optoelectronic components. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).