Passenger travel characteristics and bus operational states: a study based on IC card and GPS data in Yinchuan, China

In recent years, public transport has been developing rapidly and producing large amounts of traffic data. Emerging big data-mining techniques enable the application of these data in a variety of ways. This study uses bus intelligent card (IC card) data and global positioning system (GPS) data to estimate passenger boarding and alighting stations. First, an estimation model for boarding stations is introduced to determine passenger boarding stations. Then, the authors propose an innovative uplink and downlink information identification model (UDI) to generate information for estimating alighting stations. Subsequently, the estimation model for the alighting stations is introduced. In addition, a transfer station identification model is also developed to determine transfer stations. These models are applied to Yinchuan, China to analyze passenger flow characteristics and bus operations. The authors obtain passenger flows based on stations (stops), bus lines, and traffic analysis zones (TAZ) during weekdays and weekends. Moreover, average bus operational speeds are obtained. These findings can be used in bus network planning and optimization as well as bus operation scheduling

Spatiotemporal Patterns of Carbon Emissions and Taxi Travel Using GPS Data in Beijing

Taxis are significant contributors to carbon dioxide emissions due to their frequent usage, yet current research into taxi carbon emissions is insufficient. Emerging data sources and big data–mining techniques enable analysis of carbon emissions, which contributes to their reduction and the promotion of low-carbon societies. This study uses taxi GPS data to reconstruct taxi trajectories in Beijing. We then use the carbon emission calculation model based on a taxi fuel consumption algorithm and the carbon dioxide emission factor to calculate emissions and apply a visualization method called kernel density analysis to obtain the dynamic spatiotemporal distribution of carbon emissions. Total carbon emissions show substantial temporal variations during the day, with maximum values from 10:00–11:00 (57.53 t), which is seven times the minimum value of 7.43 t (from 03:00–04:00). Carbon emissions per kilometer at the network level are steady throughout the day (0.2 kg/km). The Airport Expressway, Ring Roads, and large intersections within the 5th Ring Road maintain higher carbon emissions than other areas. Spatiotemporal carbon emissions and travel patterns differ between weekdays and weekends, especially during morning rush hours. This research provides critical insights for taxi companies, authorities, and future studies

Exceeding 67.35% Efficient and Color Temperature Tunable White Light from Carbon Dots with Quadruple-Channel Fluorescence–Phosphorescence Emission

Luminescent carbon dots (CDs) have drawn much attention in terms of photoelectronic applications, most of which are focused on single-component white-light emission. However, it still remains a significant challenge to create high-quality white-light-emitting CDs with tunable correlated color temperatures (CCTs). The theoretical calculation is initially used to predict that the enlargement of the conjugated sp2 domain induces redshift fluorescence (FL) and room temperature phosphorescence (RTP) emissions of CDs. Guided by the theoretical predictions, single-component white-light emission from CDs with high efficiency of 67.35% and tunable CCTs from 10,803 to 3376 K is realized. These CDs exhibit quadruple-model emissions with hybrid FL/RTP components at 435 nm (FL-1)/548 nm (RTP-1) and 461–522 nm (FL-2)/525–610 nm (RTP-2), which originate from a synergy between certain P bonds with aggregation-induced emission effects and different sizes of sp2 conjugated structures, respectively. Using such CDs as conversion phosphors, we prepared three white-light-emitting diodes (WLEDs) which can emit bright cool, standard, and warm white lights with color rendering indices of 81–85. Finally, highly luminescent WLEDs are also developed by dispersing these CDs in a poly(vinyl alcohol) matrix, indicating that this provides an industrial application potential