This study tested the effects of lane width, lane position and edge shoulder width on driving behavior for a three-lane underground urban expressway. A driving simulator was used with 24 volunteer test subjects. Five lane widths (2.85, 3.00, 3.25, 3.50, and 3.75 m) and three shoulder widths (0.50, 0.75, and 1.00 m) were studied. Driving speed, lane deviation and subjective perception of driving behavior were collected as performance measures. The results show that lane and shoulder width have significant effects on driving speed. Average driving speed increases from 60.01 km/h in the narrowest lane to 88.05 km/h in the widest lane. While both narrower lanes and shoulders result in reduced speed and lateral lane deviation, the effect of lane width is greater than that of shoulder width. When the lane and shoulder are narrow, drivers in the left or right lane tend to shy away from the tunnel wall, even encroaching into the neighboring middle lane. As the lane or shoulder gets wider, drivers tend to stay in the middle of the lane. An interesting finding is that although few participants acknowledged that lane position had any great bearing on their driving behaviors, the observed driving speed is statistically higher in the left lane than in the other two lanes when the lane width is narrow (in 2.85, 3 and 3.25 m lanes). These findings provided support for amending the current design specifications of urban underground roads, such as the relationship between design speed and lane width, speed limit, and combination form of lanes.
This paper presents a new topology of the input current continuous switch boost inverter (ICCSBI) and a perturbation observation with hysteresis comparator method. Because the traditional inverter needs to join the dead time to avoid short circuit, the dead time will cause distortion of the output current. And the traditional inverter is not suitable for photovoltaic power generation because it is a buck converter. The ICCSBI structure improves the booster circuit, which refers to the Z-source inverter. It can get higher voltage than traditional inverter. Meanwhile, the ICCSBI not only retains the advantages of the Z-source inverter but also reduces the number of passive components. In addition, the hysteresis band comparator is added to the perturbation observation method to make the system better robustness at the maximum power point of the photovoltaic system. In the photovoltaic system, to ensure the output current stable, the current control method is added to the ICCSBI. Finial, the experimental results are presented to demonstrate the new topology and control method. KEYWORDS hysteresis band comparator, input current continuous switch boost inverter, maximum power point tracking (MPPT), perturbation observation method, PV system, shoot-through
The cooperative motion of multiple mobile robots has attracted wide attention due to its advantages in military, marine and aerospace fields, and formation control has become a significant technology in the realization of these tasks. However, most of the existing formation control designs of mobile robots do not consider the practical obstacles in the environment, and the maintenance of both formation and trajectory tracking while confronting the obstacles is still a challenging issue. Therefore, in this paper, a virtual-structure-based formation control approach is designed with obstacle avoidance for a system with multiple mobile robots. The basic trajectory is generated for each robot in the group and parameterized to keep the group in formation. A trajectory generator is then established regarding the obstacles, where a potential function is designed to adjust the basic trajectory and replan the reference trajectory to achieve obstacle avoidance. Then, a novel design for the path parameter is proposed to improve the performance of the robot group when encountering obstacles. Finally, a tracking controller is designed to achieve good tracking performance for robots, and the guaranteed performance is achieved via the Lyapunov theorem. A comparative simulation with three sets is carried out, where an objective function Fobj is designed to evaluate the tracking performance in the presence of obstacles. Besides this, a real experiment is implemented to further verify the effectiveness. The simulation and experimental results verify the good formation and tracking performance of the proposed design for a system with multiple mobile robots with obstacle avoidance.
Social well-being in communities has received little research attention, particularly regarding the impact of community satisfaction on social well-being. Thus, we examined the link between community satisfaction and social well-being in the Chinese cultural context, and investigated whether sense of community mediates this relationship. We collected survey data from 572 residents living in various communities in Wuhan, Hubei Province, China, and used regression analysis to test the hypotheses. Results reveal that community satisfaction was positively related to social well-being, and sense of community played a mediating role in this relationship. Our findings provide a culture- and location-specific perspective of community satisfaction and social well-being in China and highlight the importance of social well-being in community studies.
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