Although visual display terminals have been used in office work for many years, research on the effect of long time work using them is still insufficient. Also, the impact of a LED light source for all day work is not clear. In this paper, the visual fatigue caused by long-term VDT work under fluorescent and LED luminaires was investigated though subjective reports of symptoms, ophthalmological parameters and physiological signals. The results show that visual fatigue becomes more serious with increasing time spent at VDT work. Compared to fluorescent luminaires, the LED luminaires produced significantly greater near point accommodation, blink amplitude and oxygen saturation but less dry eye symptoms, less best corrected distance visual acuity and less high-frequency electrocardiogram power as time passed, although all were of small effect size. Although the participants carried out eight hours of VDT work under the two light sources, at the end the symptom ‘tired eyes’ was rated as moderate while all the other reported symptoms were rated as slight.

Using data derived from eight hours work at a visual display terminal, a model for evaluating visual fatigue under LED light sources has been developed based on five ophthalmological parameters and three physiological signals. A simplified model based on one ophthalmological parameter and one physiological signal is also proposed. Both models show a high correlation with subjective data and are confirmed by a validation experiment. The results also show that the visual fatigue occurring after eight hours of visual display terminal work under LED lighting is rather small.

The issue of global exponential robust stability is discussed for Cohen–Grossberg-type (CG-type) bidirectional associative memory (BAM) neural networks with delays. The activation functions that are adopted contain sigmoid functions and Lipschitz functions. For CG-type BAM neural networks with parameter uncertainties, which are assumed to be time invariant and bounded, by employing a Lyapunov–Krasovskii functional and linear matrix inequality (LMI) approach, the conditions ensuring global exponential robust stability are derived, which are expressed in terms of LMIs, and can be checked easily using the MATLAB LMI toolbox. In addition, when parameter uncertainties vanish, global exponential stability as a byproduct of global exponential robust stability, can also be guaranteed. Finally, two examples are provided to illustrate the effectiveness of the obtained results.

Silicon substrates were modified with octadecyltrichlorosilane and 3-Aminopropyl-triethoxysilane molecules by chemical adsorption process. The surface properties, morphology and composition were characterised by means of contact angle measurement, atomic force microscopic (AFM) analysis and X-ray photoelectron spectroscopy. To achieve quantitative results, it is important to implement the proper force calibration in AFMs. Both the lateral and the normal spring constants of the AFM cantilever were calibrated. The nanotribological properties including adhesion, friction and antiwear of silane derived surface modification are comparatively studied with the calibrated AFM cantilever. The results demonstrated that the silane derived surface modification reduces adhesion and friction. Hydrophobic methyl terminated modification possesses better friction reduction and antiwear capacity than hydrophilic amine terminated surface.