This paper aims at assessing several fast non-Hertzian methods, coupled with two wear models, based on the wheel–rail rolling contact and wear prediction. Four contact models, namely Kik-Piotrowski's method, Linder's method, Ayasse-Chollet's STRIPES algorithm and Sichani's ANALYN algorithm are employed for comparing the normal contact. For their tangential modelling, two tangential algorithms, i.e. FASTSIM and FaStrip, are used. Two commonly used wear models, namely the Archard (extended at the KTH Royal Institute of Technology) and USFD (developed by the University of Sheffield based on T-gamma approach), are further utilized for wear distribution computation. All results predicted by the fast non-Hertzian methods are evaluated against the results of Kalker's CONTACT code using penetration as the input. Since the two wear models adopt different expressions for calculating the wear performance, the attention of this paper is on assessing which one is more suitable for the fast non-Hertzian methods to utilize. The comparison shows that the combination of the USFD wear model with any of the fast non-Hertzian methods agrees better with CONTACT+USFD. In general, ANALYN+FaStrip is the best solution for the simulation of the wheel–rail rolling contact, while STRIPES+FASTSIM can provide better accuracy for the maximum wear depth prediction using the USFD wear model.

In the modeling of railway vehicle-track dynamics and wheel-rail damage, simplified tangential contact models based on ellipse assumption are usually used due to strict limitation of computational cost. Since most wheel-rail contact cases appear to be nonelliptic shapes, a fast and accurate tangential model for nonelliptic contact case is in demand. In this paper, two ellipse-based simplified tangential models (i.e., FASTSIM and FaStrip) using three alternative nonelliptic adaptation approaches, together with Kalker's NORM algorithm, are applied to wheel-rail rolling contact cases. It aims at finding the best approach for dealing with nonelliptic rolling contact. Compared to previous studies, the nonelliptic normal contact solution in the present work is accurately solved rather than simplification. Therefore, it can avoid tangential modeling evaluation affected by inaccurate normal contact solution. By comparing with Kalker's CONTACT code, it shows both FASTSIM-based and FaStrip-based models can provide accurate global creep force. With regard to local rolling contact solution, only the accuracy of FaStrip-based models is satisfactory. Moreover, Ayasse-Chollet's local ellipse approach appears to be the best choice for nonelliptic adaptation.

Lighting accounts for a large proportion of building energy use. Task lighting is effective in saving lighting energy consumption and found to improve productivity in factories, but its effects in offices remain unknown. This study aims to investigate the effects of general and task lighting on office occupants’ satisfaction, alertness, mood, and performance in simple and complex tests. A within-subject design involving 2 lighting condition (100% general lighting vs. 70% general + 30% task lighting) × 2 task type (paper-based vs. computer tasks) was adopted. The work-plane illuminance and the equivalent melanopic illuminance were controlled at the same level in two lighting conditions. The lighting power was reduced by 16.7% when introducing task lighting. 28 subjects participated in this empirical study. The results showed that different lighting conditions had no significant impact on alertness. Introducing task lighting would suppress positive mood, but improve work performance. The respond speed in simple tasks was significantly improved by 4.3%-8.5% and the correct rates in complex assessments increased by 6.2%. These findings highlight that the combination of general and task lighting reduces power consumption and benefits work performance. However, its suppression on the positive mood also needs to be considered in the lighting design.

Light environment’s non-visual effects influence people’s health and work efficiency. However, considering non-visual requirements in addition to traditional visual requirements may significantly increase lighting energy consumption. This study utilized simulation software to explore energy saving potential of changing the direction of the luminaire. A model of a single-person office with the luminaire attached to the ceiling right above the workstation was built in ECOTECT. Vertical eye-level illuminance and horizontal work-plane illuminance were calculated with luminaires of different luminous fluxes and elevation angles from downward vertical (0°-180° at an interval of 10° on both sides) using RADIANCE. Furthermore, six cases of different lighting requirements and light correlated color temperatures were considered. Based on the illuminance-versus-luminous flux coefficients obtained from simulation results, luminous fluxes were calculated to fulfill both visual and non-visual requirements under different elevation angles in all cases. It was found that compared to traditional lighting design with the luminaire facing vertically downwards, turning the luminaire at an elevation angle of 50° reduced the required luminous flux by up to 22.7%, which would benefit energy savings. Therefore, changing the direction of the luminaire has the potential to improve office lighting energy efficiency when considering both visual and non-visual requirements.