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  • Open Access


    Calcul de similarité sémantique entre trajectoires

    Clément Moreau, Thomas Devogele, Laurent Etienne

    Revue Internationale de Géomatique, Vol.29, No.1, pp. 107-128, 2019, DOI:10.3166/rig.2019.00077

    Abstract Understanding mobility, whether physical in the spatial sense or virtual in the web navigation sense, raises many challenges in terms of monitoring individuals, spatial planning or activity recommendations. Having access today to many resources on the contextual nature of this mobility, one of the current concerns is to succeed in identifying groups of similar individuals with regard to their mobility. To do this, we propose a semantic trajectory model enriched by ontologies at the level of contextual data and allowing us to calculate the similarity between each episode of individual mobility. Subsequently, an editing distance is used to evaluate in… More >

  • Open Access


    Influence of Wellbore Trajectory on Pressure Drop and Fluid Discharge

    Ruidong Wu1, Guowei Wang2,3,4,*, Zhixing Yang1, Ruiquan Liao2,3,4, Yang Cheng2,3,4

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.8, pp. 2053-2066, 2023, DOI:10.32604/fdmp.2023.026301

    Abstract An experimental analysis has been conducted to study the process of fluid accumulation for different borehole trajectories. More specifically, five heel angles have been experimentally realized to simulate the borehole trajectory of the sloping section of the formation. The fluid-carrying capacity, pressure drop and fluid discharge volatility have been investigated for these conditions and, accordingly, the relationship between heel angle and wellbore pressure drop fluid-carrying capacity has been determined. The results show that while the reasonable roll angle can increase the pressure loss in the wellbore, it is beneficial to drainage. In terms of pressure loss and liquid-carrying capacity, when… More > Graphic Abstract

    Influence of Wellbore Trajectory on Pressure Drop and Fluid Discharge

  • Open Access


    Association between Occupational Change Trajectories and Mental Health: Results from the Korean Longitudinal Study of Aging

    Jeong Min Yang1,2, Hyeon Ji Lee1, Jae Hyun Kim1,2,3,*

    International Journal of Mental Health Promotion, Vol.25, No.4, pp. 579-594, 2023, DOI:10.32604/ijmhp.2022.027498

    Abstract Objectives: This study was to longitudinally investigate the association between occupational change trajectories and mental health in the Korean population aged 45 years and older from the Korean Longitudinal Study of Aging (KLoSA). Methods: After excluding missing values, the data of 6,224 participants from the first to eighth waves of the KLoSA were analyzed using t-test, Analysis of variance (ANOVA), Group-based Trajectory Model (GBTM) from 1–5th KLoSA and Time-Lagged Generalized estimating equation (GEE) model from 5–8th KLoSA to analyze the association between occupational change trajectories and mental health in the Korean population aged 45 years and older. Results: An analysis… More >

  • Open Access


    Numerical Simulation about the Characteristics of the Store Released from the Internal Bay in Supersonic Flow

    Xiaohui Cheng1, Haiqing Si1,*, Yao Li1, Peihong Zhang2

    CMES-Computer Modeling in Engineering & Sciences, Vol.136, No.2, pp. 1729-1742, 2023, DOI:10.32604/cmes.2023.022694

    Abstract To understand the influence of the initial release conditions on the separation characteristics of the store and improve it under high Mach number (Ma = 4) flight conditions, the overset grid method and the Realizable turbulence model coupled with an equation with six degrees of freedom are used to simulate the store released from the internal bay. The motion trajectory and the attitude angle of the store separation under the conditions of different centroid, velocity, height and control measures are given by the calculated result. Through analysis, the position of the centroid will affect the separation of the store, which needs to… More >

  • Open Access


    Optimal Strategies Trajectory with Multi-Local-Worlds Graph

    Xiang Yu1, Chonghua Wang2, Xiaojing Zheng3,*, Chaoyu Zeng4, Brij B. Gupta5,6,7

    CMC-Computers, Materials & Continua, Vol.75, No.1, pp. 2079-2099, 2023, DOI:10.32604/cmc.2023.034118

    Abstract This paper constructs a non-cooperative/cooperative stochastic differential game model to prove that the optimal strategies trajectory of agents in a system with a topological configuration of a Multi-Local-World graph would converge into a certain attractor if the system’s configuration is fixed. Due to the economics and management property, almost all systems are divided into several independent Local-Worlds, and the interaction between agents in the system is more complex. The interaction between agents in the same Local-World is defined as a stochastic differential cooperative game; conversely, the interaction between agents in different Local-Worlds is defined as a stochastic differential non-cooperative game.… More >

  • Open Access


    DQN-Based Proactive Trajectory Planning of UAVs in Multi-Access Edge Computing

    Adil Khan1,*, Jinling Zhang1, Shabeer Ahmad1, Saifullah Memon2, Babar Hayat1, Ahsan Rafiq3

    CMC-Computers, Materials & Continua, Vol.74, No.3, pp. 4685-4702, 2023, DOI:10.32604/cmc.2023.034892

    Abstract The main aim of future mobile networks is to provide secure, reliable, intelligent, and seamless connectivity. It also enables mobile network operators to ensure their customer’s a better quality of service (QoS). Nowadays, Unmanned Aerial Vehicles (UAVs) are a significant part of the mobile network due to their continuously growing use in various applications. For better coverage, cost-effective, and seamless service connectivity and provisioning, UAVs have emerged as the best choice for telco operators. UAVs can be used as flying base stations, edge servers, and relay nodes in mobile networks. On the other side, Multi-access Edge Computing (MEC) technology also… More >

  • Open Access


    Efficient Power Control for UAV Based on Trajectory and Game Theory

    Fadhil Mukhlif1,*, Ashraf Osman Ibrahim2, Norafida Ithnin1, Roobaea Alroobaea3, Majed Alsafyani3

    CMC-Computers, Materials & Continua, Vol.74, No.3, pp. 5589-5606, 2023, DOI:10.32604/cmc.2023.034323

    Abstract Due to the fact that network space is becoming more limited, the implementation of ultra-dense networks (UDNs) has the potential to enhance not only network coverage but also network throughput. Unmanned Aerial Vehicle (UAV) communications have recently garnered a lot of attention due to the fact that they are extremely versatile and may be applied to a wide variety of contexts and purposes. A cognitive UAV is proposed as a solution for the Internet of Things ground terminal’s wireless nodes in this article. In the IoT system, the UAV is utilised not only to determine how the resources should be… More >

  • Open Access


    Fusing Spatio-Temporal Contexts into DeepFM for Taxi Pick-Up Area Recommendation

    Yizhi Liu1,3, Rutian Qing1,3, Yijiang Zhao1,3,*, Xuesong Wang1,3, Zhuhua Liao1,3, Qinghua Li1,2, Buqing Cao1,3

    Computer Systems Science and Engineering, Vol.45, No.3, pp. 2505-2519, 2023, DOI:10.32604/csse.2023.021615

    Abstract Short-term GPS data based taxi pick-up area recommendation can improve the efficiency and reduce the overheads. But how to alleviate sparsity and further enhance accuracy is still challenging. Addressing at these issues, we propose to fuse spatio-temporal contexts into deep factorization machine (STC_DeepFM) offline for pick-up area recommendation, and within the area to recommend pick-up points online using factorization machine (FM). Firstly, we divide the urban area into several grids with equal size. Spatio-temporal contexts are destilled from pick-up points or points-of-interest (POIs) belonged to the preceding grids. Secondly, the contexts are integrated into deep factorization machine (DeepFM) to mine… More >

  • Open Access


    Experimental and Numerical Analysis of Particle Migration and Patterning Behavior in a Gravel Pack

    Bobo Luo1,*, Yunbin Xiong1, Zhuoyi Li2, Zhanqing Qu3, Fenggang Liu1, Tiankui Guo3, Zugui Yang1, Yina Shi1

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.4, pp. 911-928, 2023, DOI:10.32604/fdmp.2022.022761

    Abstract Due to its long lifespan and high sand-removal efficiency, gravel packing is one of the most applied sand control methods during the recovery of reservoirs with sanding problems. The blockage and retention of injected sand in a gravel pack is a complex process affected by multiple mechanisms. The majority of existing studies based on the phenomenological deep bed filtration (DBF) theory focused on the gravel pack’s overall permeability damage and failed to obtain the inner-pore particle distribution pattern. In this work, experiments and simulations were carried out to reveal the particle distribution in a gravel pack during flooding. In particular,… More >

  • Open Access


    Forecasting Future Trajectories with an Improved Transformer Network

    Wei Wu1, Weigong Zhang1,*, Dong Wang1, Lydia Zhu2, Xiang Song3

    CMC-Computers, Materials & Continua, Vol.74, No.2, pp. 3811-3828, 2023, DOI:10.32604/cmc.2023.029787

    Abstract An increase in car ownership brings convenience to people’s life. However, it also leads to frequent traffic accidents. Precisely forecasting surrounding agents’ future trajectories could effectively decrease vehicle-vehicle and vehicle-pedestrian collisions. Long-short-term memory (LSTM) network is often used for vehicle trajectory prediction, but it has some shortages such as gradient explosion and low efficiency. A trajectory prediction method based on an improved Transformer network is proposed to forecast agents’ future trajectories in a complex traffic environment. It realizes the transformation from sequential step processing of LSTM to parallel processing of Transformer based on attention mechanism. To perform trajectory prediction more… More >

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