Lane change (LC) is an essential feature of expressway driving behavior that affects traffic efficiency and safety. Thus, a wrongful execution of LC, could be due to the wrong choice of gap distance before the LC manoeuvre. This might lead to road crashes, mostly in form rear-end, sideswipe, or angled collision. This research evaluates the characteristics of drivers’ Following Gap Distance (FGD) during LC using VISSIM traffic simulation program. Data were collected along a representative segment along with Kuala Lumpur – Seremban expressway for two days using an instrumented vehicle approach. A passenger car was instrumented with a Video Velocity Box (VBox), an on-board data acquisition system used for video recording of the road’s traffic event. A total of 75 and 20 following incidences of lane changing were observed in first and second day, respectively. Standstill Distance (CC0), Gap Time (CC1) and Following Distance Oscillation (CC2) were used as calibration parameters in VISSIM model. FGD was used as a measure of performance for the model. The data from second day was used for model validation. The findings indicate that the model was well calibrated and validated. Therefore, it can be used for modelling various scenarios involving LC on the expressway.
The ventilation system of a hospital operating room is used to provide comfortable and healthy environment. The healthy environment can be achieved by minimizing the risk of contamination through filtration and air distribution scheme. This paper involves numerical study for different ventilation systems studying the effect of air distribution on bacteria diffusion and the indoor air quality by using (CFD) techniques. Five different configurations ventilation systems based on Hospital guidelines standards conditions are applied on a selected model to evaluate the efficiency of ventilation systems in minimizing the risk of postoperative infection. It is concluded that the fourth configurations (laminar airflow (LAF) and exhausts from low level at two sides exhorts) which matching with DIN and ASHRAE Standard is the most efficient which satisfies the comfort conditions and provides protection against infection.
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