Valve closure based on pump runaway characteristics in long distance pressurized systems

In order to guarantee the safety of pumps, valves are installed at the outlet of each pump in long-distance pressurized water supply systems. However, water hammer pressure caused by improper valve closure can tremendously exceed the standard of the pipeline. In this paper, the effects of valve closure on speed of pump and pressure along the pipeline were investigated. Valve closure formula based on pump runaway characteristics were proposed and verified using numerical simulation. In addition, when valves were closed under the formula proposed in this paper and other closure laws, the minimum speed, minimum and maximum pressure along the pipeline were compared. The results showed that formulas agree well with the numerical results. In the high lift supply systems, compared with the other closure laws, the minimum speed and minimum pressure along the pipeline under valve closure formula were the largest, and the maximum pressure along the pipeline was the smallest. Moreover, in the low lift supply systems, the minimum speed under valve closure formula did not exceed the rated speed. Compared with the other closure laws, the minimum pressure along the pipeline was the largest and the maximum pressure along the pipeline was the smallest.

Deadlock-Free Planner for Occluded Intersections Using Estimated Visibility of Hidden Vehicles

A common approach used for planning blind intersection crossings is to assume that hypothetical vehicles are approaching the intersection at a constant speed from the occluded areas. Such an assumption can result in a deadlock problem, causing the ego vehicle to remain stopped at an intersection indefinitely due to insufficient visibility. To solve this problem and facilitate safe, deadlock-free intersection crossing, we propose a blind intersection planner that utilizes both the ego vehicle and the approaching vehicle’s visibility. The planner uses a particle filter and our proposed visibility-dependent behavior model of approaching vehicles for predicting hidden vehicles. The behavior model is designed based on an analysis of actual driving data from multiple drivers crossing blind intersections. The proposed planner was tested in a simulation and found to be effective for allowing deadlock-free crossings at intersections where a baseline planner became stuck in a deadlock. The effects of perception accuracy and sensor position on output motion were also investigated. It was found that the proposed planner delayed crossing motion when the perception was imperfect. Furthermore, our results showed that the planner decelerated less while crossing the intersection with the front-mounted sensor configuration compared to the roof-mounted configuration due to the improved visibility. The minimum speed difference between the two sensor configurations was 1.82 m/s at an intersection with relatively poor visibility and 1.50 m/s at an intersection with good visibility.

Driver stopping behavior at stop-controlled intersections with sightline limitations

Though drivers approaching a stop-sign-controlled intersection are legally required to stop at the limit line if one is present, it is well established that many drivers fail to do so. At many intersections, stopping at the limit line does not afford drivers a full view of approaching traffic, so drivers must travel past the limit line to overcome sightline obstructions including vegetation, buildings, or parked vehicles. In the present observational study, typical driver stopping/slowing behavior was studied via a camera placed at three stop-sign-controlled T-intersections. The presence of buildings at the corner of two intersections, obstructing drivers’ sightlines, explained variation in stopping behaviors across intersections. While drivers were more likely to stop at these two intersections, they reached a minimum speed further past the limit line. The findings support overcoming sight restrictions as one possible reason for the commonly observed behavior of drivers slowing or stopping beyond the limit line.

Design of Savonius-Darrieus A Hybrid Wind Turbine

Savonius wind turbine design use type two blades with a diameter of 15.5 cm, a height of 10.9 cm and turbine weight of 51.3 g. The Darrieus wind turbine design uses type three blades with dimensions 21.8 cm x 8.7 cm x 2.3 cm. The weight of each blade is 51.3 g with the angle between the blades being 120⁰ . The voltage of 2.5 V produced a minimum turbine rotation speed of 284.2 rpm and a maximum of 296.0 rpm. When the voltage was increased to 5.0 V, the minimum speed is 342.8 rpm and a maximum speed of 366.4 rpm. When given a voltage of 7.5 V, a minimum speed of 461.7 rpm and a maximum of 481.3 rpm were produced.