Distribution Optimization Model for Passenger Departure via Multimodal Transit

International airports in China have become a complex hub between airport and multimodal transit stations. Dissimilar passenger departure demands in different transit mode cause wide gaps among departure times from airport to these modes. In this context, hub managers need to balance the distribution of air passengers to transit modes in order to reduce departure delays and alleviate the congestion in transit stations, even though they cannot change the operating plan of airport or transit stations. However, few research efforts have addressed this distribution. Therefore, we developed a distribution optimization model for passenger departure that minimizes the average departure time and is solved by Genetic Algorithm. To describe differences in passenger choices, without taking into consideration the metropolitan transportation network outside the airport, we introduced the concept of rigid and elastic departures. To reflect the tendency of elastic passengers to choose different transit modes, we assume that the passengers change to other modes in different proportions. A case revealed that the presence of rigid passengers allows managers to partly balance the distribution of passengers and improve the average departure time. When the volume of passengers approaches the peak volume, the optimized distribution significantly improves the departure time

Monitoring land cover change and disturbance of the Mount Wutai World Cultural Landscape Heritage Protected Area based on Remote Sensing time-series image from 1987 to 2018

The contextual-based multi-source time-series remote sensing and proposed Comprehensive Heritage Area Threats Index (CHATI) index are used to analyze the spatiotemporal land use/land cover (LULC) and threats to the Mount Wutai World Heritage Area. The results show disturbances, such as forest coverage, vegetation conditions, mining area, and built-up area, in the research area changed dramatically. According to the CHATI, although different disturbances have positive or negative influences on environment, as an integrated system it kept stable from 1987 to 2018. Finally, this research uses linear regression and the F-test to mark the remarkable spatial-temporal variation. In consequence, the threats on Mount Wutai be addressed from the macro level and the micro level. Although there still have some drawbacks, the effectiveness of threat identification has been tested using field validation and the results are a reliable tool to raise the public awareness of WHA protection and governance

AATCT-IDS: A Benchmark Abdominal Adipose Tissue CT Image Dataset for Image Denoising, Semantic Segmentation, and Radiomics Evaluation

Methods: In this study, a benchmark \emph{Abdominal Adipose Tissue CT Image Dataset} (AATTCT-IDS) containing 300 subjects is prepared and published. AATTCT-IDS publics 13,732 raw CT slices, and the researchers individually annotate the subcutaneous and visceral adipose tissue regions of 3,213 of those slices that have the same slice distance to validate denoising methods, train semantic segmentation models, and study radiomics. For different tasks, this paper compares and analyzes the performance of various methods on AATTCT-IDS by combining the visualization results and evaluation data. Thus, verify the research potential of this data set in the above three types of tasks. Results: In the comparative study of image denoising, algorithms using a smoothing strategy suppress mixed noise at the expense of image details and obtain better evaluation data. Methods such as BM3D preserve the original image structure better, although the evaluation data are slightly lower. The results show significant differences among them. In the comparative study of semantic segmentation of abdominal adipose tissue, the segmentation results of adipose tissue by each model show different structural characteristics. Among them, BiSeNet obtains segmentation results only slightly inferior to U-Net with the shortest training time and effectively separates small and isolated adipose tissue. In addition, the radiomics study based on AATTCT-IDS reveals three adipose distributions in the subject population. Conclusion: AATTCT-IDS contains the ground truth of adipose tissue regions in abdominal CT slices. This open-source dataset can attract researchers to explore the multi-dimensional characteristics of abdominal adipose tissue and thus help physicians and patients in clinical practice. AATCT-IDS is freely published for non-commercial purpose at: \url{https://figshare.com/articles/dataset/AATTCT-IDS/23807256}.Comment: 17 pages, 7 figure

Location Design of Electrification Road in Transportation Networks for On-Way Charging

Electric vehicles tend to be a great mobility option for the potential benefits in energy consumption and emission reduction. On-way charging (OWC) has been recognized to be a promising solution to extend driving range for electric vehicles. Location of the electrification road (ER) is a critical issue for future urban traffic management to accommodate the new mobility option. This paper proposes a mathematical program with equilibrium constraint (MPEC) approach to solve this problem, which minimizes the total travel time with a limited construction budget. To describe the drivers’ routing choice, a path-constrained network equilibrium model is proposed to minimize their travel time and prevent running out of charge. We develop a modified active set algorithm to solve the MPEC model. Numerical experiments are presented to demonstrate the performance of the model and the solution algorithm and analyze the impact of charging efficiency, battery size, and comfortable range

Simulation-Based Optimization for the Operation of Toll Plaza at Car Park Exit with Mixed Types of Tollbooths and Waiting-Time-Dependent Service

This study presents an approach of simulation-based optimization to the operation of the toll plaza at the car park exit. We first propose a simulation model, as the representation of the queueing system for the toll plaza with mixed-type customers and servers where the service time is dependent on the waiting time of customer. Then, a simulation-based integer programming model is developed to design more traffic-efficient yet cost-effective operation schemes. It is decomposed by a rolling horizon approach into subproblems which are all solved via the Kriging metamodel algorithm. A numerical example is presented to illustrate the model and offer insight on how to achieve traffic efficiency and cost-effectiveness

Orbital elements ephemerides and interfaces design of LEO satellites

Low earth orbit satellites, with unique advantages, are prosperous types of navigation augmentation satellites for the GNSS satellites constellations. The broadcast ephemeris element needs to be designed as an important index of the augmented LEOs. The GPS ephemerides of 16/18 elements cannot be directly applied to the LEOs because of the poor fitting accuracies in along-track positional component. Besides, the ill-conditioned problem of the normal-matrix exists in fitting algorithm due to the small eccentricity of the LEO orbits. Based on the nonsingular orbital elements, 5 sets of ephemerides with element numbers from 16 to 19 were designed respectively by adding or modifying orbital elements magnifying the along-track and radial positional components. The fitting experiments based on the LEO of 300 to 1500 km altitudes show that the fitting UREs of the proposed 16/17/18/18*/19-element ephemerides are better than 10/6/4/5/2.5 cm, respectively. According to the dynamical range of the fitting elements, the interfaces were designed for the 5 sets of ephemerides. The effects of data truncation on fitting UREs are at millimeter level. The total bits are 329/343/376/379/396, respectively. 29/15 bits are saved for the 16/17-element ephemerides compared with the GPS16 ephemeris, while 64/61/41 bits can be saved for the 18/18*/19-element ephemerides compared with the GPS18 elements ephemeris

GEO NAV/CNAV-type Broadcast Ephemeris Fitting without Rotation of Inclination

The GPS-type broadcast ephemerides are currently used by BDS constellation. However, a 5°-rotation added on the original orbital inclination is needed in the GEOs ephemeris parameters fitting algorithm as well as in the user satellite position computation because of the singularity due to small inclination. Besides, the phenomena of exceeding the given boundary happen occasionally for some ephemeris parameters of GEOs. In order to unify the user ephemerides algorithm for the hybrid constellation, a two-step GEO broadcast ephemerides fitting algorithm was analyzed based on the first class nonsingular orbital elements. After the investigation on the reason for the variations of some ephemeris parameters out of limited range, a reduced fitting parameter set was adopted by giving the underlying one or two parameters with fixed values. Fit simulations for 5 GEOs during both eclipsing and non-eclipsing periods show that the two-step fitting algorithm has considerable robustness to ensure the success rate and fitting accuracy. The mean fitting user range error of GEOs with 2 h for NAV and 3 h data set for CNAV are better than 3 mm. For specific fit arcs with the boundary-exceeding problem, it can be fully avoided by using the fitting algorithm with a reduced fitting parameter set. However, the fitting URE will increase to 2 cm

Analysis of Perception Accuracy of Roadside Millimeter-Wave Radar for Traffic Risk Assessment and Early Warning Systems

Millimeter-wave (MMW) radar is essential in roadside traffic perception scenarios and traffic safety control. For traffic risk assessment and early warning systems, MMW radar provides real-time position and velocity measurements as a crucial source of dynamic risk information. However, due to MMW radar’s measuring principle and hardware limitations, vehicle positioning errors are unavoidable, potentially causing misperception of the vehicle motion and interaction behavior. This paper analyzes the factors influencing the MMW radar positioning accuracy that are of major concern in the application of transportation systems. An analysis of the radar measuring principle and the distributions of the radar point cloud on the vehicle body under different scenarios are provided to determine the causes of the positioning error. Qualitative analyses of the radar positioning accuracy regarding radar installation height, radar sampling frequency, vehicle location, posture, and size are performed. The analyses are verified through simulated experiments. Based on the results, a general guideline for radar data processing in traffic risk assessment and early warning systems is proposed

A labor-free index-guided semantic segmentation approach for urban vegetation mapping from high-resolution true color imagery

Accurate and timely information on urban vegetation (UV) can be used as an important indicator to estimate the health of cities. Due to the low cost of RGB cameras, true color imagery (TCI) has been widely used for high spatial resolution UV mapping. However, the current index-based and classifier-based UV mapping approaches face problems of the poor ability to accurately distinguish UV and the high reliance on massive annotated samples, respectively. To address this issue, an index-guided semantic segmentation (IGSS) framework is proposed in this paper. Firstly, a novel cross-scale vegetation index (CSVI) is calculated by the combination of TCI and Sentinel-2 images, and the index value can be used to provide an initial UV map. Secondly, reliable UV and non-UV samples are automatically generated for training the semantic segmentation model, and then the refined UV map can be produced. The experimental results show that the proposed CSVI outperformed the existing five RGB vegetation indices in highlighting UV cover and suppressing complex backgrounds, and the proposed IGSS workflow achieved satisfactory results with an OA of 87.72% ∼ 88.16% and an F1 score of 87.73% ∼ 88.37%, which is comparable with the fully-supervised method

Periodic Variations of BeiDou Satellite Clock Offsets Derived from Multi-satellite Orbit Determination

Multi-satellite orbit determination based on global tracking network can generate satellite orbit and clock products for BDS at the same time. The errors in the two resulting products, however, are difficult to be decoupled completely. There might be periodic fluctuations existing in the satellite clock offsets. Restricted by current imperfect global tracking network, loses of navigation files and software settings, there exist a lot of data gaps in the BeiDou satellite orbit and clock products. A spectrum analysis method applicable to data with gaps was used, and the main periodic items of BeiDou satellite clock offsets were extracted with it. Two improved clock prediction models augmented with periodic corrections were proposed and the prediction accuracy within 24 hours was evaluated. The tested results with nearly one-year-long data showed that the three main periods in BeiDou GEO and IGSO satellite clock offsets are 12, 24 and 8 hours, respectively, while those for MEOs are 12.91, 6.44 and 24 hours. Compared with the conventional clock model of quadratic polynomial, the improved model can increase the prediction accuracy of BeiDou GEO and IGSO satellite clock offsets by 20 to 40 percent at spans less than 24 hours