Activity of vehicles in the bus rapid transit system Metrobús in Mexico City

In this paper, we analyze a massive dataset with registers of the movement of vehicles in the bus rapid transit system Metrobús in Mexico City from February 2020 to April 2021. With these records and a division of the system into 214 geographical regions (segments), we characterize the vehicles’ activity through the statistical analysis of speeds in each zone. We use the Kullback–Leibler distance to compare the movement of vehicles in each segment and its evolution. The results for the dynamics in different zones are represented as a network where nodes define segments of the system Metrobús and edges describe similarity in the activity of vehicles. Community detection algorithms in this network allow the identification of patterns considering different levels of similarity in the distribution of speeds providing a framework for unsupervised classification of the movement of vehicles. The methods developed in this research are general and can be implemented to describe the activity of different transportation systems with detailed records of the movement of users or vehicles.

Design of a rapid transit to Mars mission using laser-thermal propulsion

The application of directed energy to spacecraft mission design is explored using rapid transit to Mars as the design objective. An Earth-based laser array of unprecedented size (10-m diameter) and power (100 MW) is assumed to be enabled by ongoing developments in photonic laser technology. A phased-array laser of this size and incorporating atmospheric compensation would be able to deliver laser power to spacecraft in cislunar space, where the incident laser is focused into a hydrogen heating chamber via an inflatable reflector. The hydrogen propellant is then exhausted through a nozzle to realize specific impulses of 3000 s. The architecture is shown to be immediately reusable via a burn-back maneuver to return the propulsion unit while still within range of the Earth-based laser. The ability to tolerate much greater laser fluxes enables realizing the combination of high thrust and high specific impulse, making this approach favorable in comparison to laser-electric propulsion and occupying a parameter space similar to gas-core nuclear thermal rockets (without the requisite reactor). The heating chamber and its associated regenerative cooling and propellant handling systems are crucial elements of the design that receive special attention in this study. The astrodynamics and the extreme aerocapture maneuver required at Mars arrival after a 45-day transit are also analyzed in detail. The application of laser-thermal propulsion as an enabling technology for other rapid transit missions in the solar system and beyond is discussed.

TEXT CLUSTERING APPROACH TOWARD COMMUNITY EXPECTATIONS TO THE BUS RAPID TRANSIT (BRT) TRANSJATENG PURWOKERTO-PURBALINGGA OPERATIONS

Bus Rapid Transit (BRT) is one of the alternative public transportations in urban areas, which has begun to be implemented in some cities of Indonesia. By finding out the effectiveness of BRT as a mass transportation system, it is necessary to study the expectations of users and non-users of the Trans Jateng Purwokerto-Purbalingga BRT regarding the perceived social, economic, and environmental impacts. This study uses the text Clustering method to group public opinion based on similarities so that it can be analyzed further for policymaking. As a result, the majority of the community gave positive expectations of BRT implementation’s perceived social, economic, and environmental benefits. On the other hand, public opinion on the presence of BRT is not always positive and has a significant impact. Improvements are needed in several aspects that are considered not to meet public expectations to maximize the function of BRT as a substitute for public transportation for private vehicles.