A linear model for determining coordination of two adjacent signalized intersections
Purpose – Urban networks are usually divided into several open or closed sub‐networks. Signal coordination has been recognized as one of the most efficient methods of controlling sub‐networks that have independently optimized timing plans. However, coordinating adjacent intersections in a network is a basic prerequisite to optimizing signal‐timing plans for sub‐networks. This paper aims to develop a linear model to support decisions regarding coordination of adjacent signals.Design/methodology/approach – This paper aims to develop a linear model to support decisions regarding coordination of adjacent signals. The tests of this model which using the field data differ from those for calibration from various roadways, indicating that the model has transferability. Evaluations using microscopic simulation show that the model can objectively determine whether or not to interconnect adjacent signals depending on various traffic demands.Findings – The model was calibrated by stepwise regression analysis with a t...
ANALYSIS OF PLATOON DISPERSION WITH RESPECT TO TRAFFIC VOLUME
Platoon dispersion depends on friction. The authors hypothesize that this friction can be external and internal and that the internal friction depends on traffic density and volume. Platoon dispersion should consequently be influenced by traffic density and volume. This hypothetical relationship was confirmed by limited field observations and simulations. Platoon dispersion increases with increasing volume up to a maximum value, which is observed at lower volumes than capacity. Dispersion decreases with further increasing volume and becomes nearly zero at volumes near capacity. If further studies confirm the observed relationship, platoon dispersion could be calculated directly from densities or volumes and travel times, applied to Robertson's model on a link by link basis, thus improving the results of traffic signal coordination models.
Ceramic microwave antennas for mobile applications
Due to their medium to high permittivity values, ceramic microwave materials are attractive as building blocks for miniaturised antenna solutions. Further advantages are low dielectric losses and an excellent temperature stability of standard ceramic materials. Yet, the permittivity of the ceramic material also has a strong influence on the radiation efficiency and bandwidth of the antenna. This implies that in the design process a suitable compromise has to be found between the degree of miniaturisation on the one hand and the antenna efficiency and bandwidth on the other. We describe two approaches towards efficient miniaturised ceramic microwave antennas: the dielectric resonator antenna (DRA) with partial metallisation and the shorting post patch antenna. We focus on design steps taken to ensure both a high degree of miniaturisation and high values of the radiation efficiency, the choice of the ceramic material and the experimental performance of the antennas.