As a solution to the breaking of pipeline under high axial force,carbon fiber composite pipe with low density and high intensity is applied to deep-sea mining transporting system.Based on the fact that the transportin...As a solution to the breaking of pipeline under high axial force,carbon fiber composite pipe with low density and high intensity is applied to deep-sea mining transporting system.Based on the fact that the transporting pipe is under the forces of gravity,inner liquid,buoyancy as well as hydrodynamic force,geometric nonlinear finite element theory has been applied to analyzing the transporting system.Conclusions can be drawn as follows.Under the interaction of waves and currents,node forces FX and FZ acted by the transporting pipe on the mining vehicle are less than 2 kN,which indicates that waves and currents have little influence on the spatial shape of the transporting pipe and the mining vehicle movement.On the other hand,the horizontal force acting on the mining ship could be as large as 106 830 N,which has great influence on the mining system.展开更多
The paper was a truck transporting system that based on system engineering theory and driver, truck-and-train, road and transporting environment were essential factors. It analyzed andstudied nine subsystems consisted...The paper was a truck transporting system that based on system engineering theory and driver, truck-and-train, road and transporting environment were essential factors. It analyzed andstudied nine subsystems consisted of the tfour tactors, ensured running safety, high efficieney and lowconsumption of transporting truck and increased using time of truck and road.展开更多
The mechanism of the nonlinear concentration dependence of the intestinal absorption of fluorescein isothiocyanate dextran 4,000 (FD-4) was studied using in situ rat intestinal loops and the in vitro Ussing-type chamb...The mechanism of the nonlinear concentration dependence of the intestinal absorption of fluorescein isothiocyanate dextran 4,000 (FD-4) was studied using in situ rat intestinal loops and the in vitro Ussing-type chamber method. The intestinal absorption rate constant of FD-4, as evaluated by the intestinal loop method, increased significantly in a nonlinear fashion as the FD-4 concentration increased up to 0.2 mM and tended to decrease at concentrations higher than 0.2 mM. The mucosal-to-serosal permeation of FD-4 across rat ileal sheets, as evaluated by the in vitro Ussing-type chamber method, also increased in a nonlinear fashion in the low concentration range (0.01 - 0.02 mM), before decreasing as the concentration increased further, whereas serosal-to-mucosal permeation decreased in a concentration-dependent manner. In addition, mucosal-to-serosal flux and serosal-to-mucosal flux were increased and reduced in the presence of the metabolic inhibitor 2, 4-dinitrophenol, respectively. These results suggest that FD-4 is predominantly secreted into the intestinal lumen by an efflux transport system.展开更多
To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migong...To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migongquan(MGQ))in Sixi valley,western Hubei,China.Highresolution continuous monitoring was utilized to obtain breakthrough curves(BTCs),which were then analyzed using the multi-dispersion model(MDM)and the two-region nonequilibrium model(2RNE)with basic parameters calculated by CXTFIT and QTRACER2.Results showed that:(1)YQD flow system had a complex infiltration matrix with overland flow,conduit flow and fracture flow,while the MGQ flow system was dominated by conduit flow with fast flow transport velocity,but also small amount of fracture flow there;(2)They were well fitted based on the MDM(R^2=0.928)and 2RNE(R^2=0.947)models,indicating that they had strong adaptability in the karst trough zone;(3)conceptual models for YQD and MGQ groundwater systems were generalized.In YQD system,the solute was transported via overland flow during intense rainfall,while some infiltrated down into fissures and conduits.In MGQ system,most were directly transported to spring outlet in the fissureconduit network.展开更多
Thedeployment of the Internet of Things(IoT)with smart sensors has facilitated the emergence of fog computing as an important technology for delivering services to smart environments such as campuses,smart cities,and ...Thedeployment of the Internet of Things(IoT)with smart sensors has facilitated the emergence of fog computing as an important technology for delivering services to smart environments such as campuses,smart cities,and smart transportation systems.Fog computing tackles a range of challenges,including processing,storage,bandwidth,latency,and reliability,by locally distributing secure information through end nodes.Consisting of endpoints,fog nodes,and back-end cloud infrastructure,it provides advanced capabilities beyond traditional cloud computing.In smart environments,particularly within smart city transportation systems,the abundance of devices and nodes poses significant challenges related to power consumption and system reliability.To address the challenges of latency,energy consumption,and fault tolerance in these environments,this paper proposes a latency-aware,faulttolerant framework for resource scheduling and data management,referred to as the FORD framework,for smart cities in fog environments.This framework is designed to meet the demands of time-sensitive applications,such as those in smart transportation systems.The FORD framework incorporates latency-aware resource scheduling to optimize task execution in smart city environments,leveraging resources from both fog and cloud environments.Through simulation-based executions,tasks are allocated to the nearest available nodes with minimum latency.In the event of execution failure,a fault-tolerantmechanism is employed to ensure the successful completion of tasks.Upon successful execution,data is efficiently stored in the cloud data center,ensuring data integrity and reliability within the smart city ecosystem.展开更多
In industrial applications,plate-like structures such as steel strips in continuous hot-dip galvanizing and papers under fan action are ubiquitous.The vibration issues that arise when these structures are in axial mot...In industrial applications,plate-like structures such as steel strips in continuous hot-dip galvanizing and papers under fan action are ubiquitous.The vibration issues that arise when these structures are in axial motion,and are influenced by fluids and thermal fields,have attracted significant attention from the academic community.This study focuses on the nonlinear dynamic behavior of axially transporting immersed viscoelastic plates with particular emphasis on internal resonance and speed-dependent tension.The governing equation and the related boundary conditions for the axially transporting viscoelastic immersed plate are derived with Hamilton's principle,prioritizing the impact of time-varying tension induced by speed perturbations.Based on the second-order Galerkin truncation,the governing equation is discretized into a system of second-order ordinary differential equations.The multi-scale method is used to analyze the stable steady-state response of the immersed viscoelastic plate.The conditions for achieving a 3:1 frequency ratio between the first two orders of the system are analytically deduced.Notably,when the viscoelastic coefficient diminishes,the stability boundaries exhibit increased complexity,manifesting as the irregular W-shaped contours in the parameter space.Numerical examples comprehensively investigate the effects of viscoelasticity on both the stability region and the steady-state response under internal resonance conditions.Finally,the accuracy of the obtained results is validated through numerical computation.展开更多
Transportation systems are experiencing a significant transformation due to the integration of advanced technologies, including artificial intelligence and machine learning. In the context of intelligent transportatio...Transportation systems are experiencing a significant transformation due to the integration of advanced technologies, including artificial intelligence and machine learning. In the context of intelligent transportation systems (ITS) and Advanced Driver Assistance Systems (ADAS), the development of efficient and reliable traffic light detection mechanisms is crucial for enhancing road safety and traffic management. This paper presents an optimized convolutional neural network (CNN) framework designed to detect traffic lights in real-time within complex urban environments. Leveraging multi-scale pyramid feature maps, the proposed model addresses key challenges such as the detection of small, occluded, and low-resolution traffic lights amidst complex backgrounds. The integration of dilated convolutions, Region of Interest (ROI) alignment, and Soft Non-Maximum Suppression (Soft-NMS) further improves detection accuracy and reduces false positives. By optimizing computational efficiency and parameter complexity, the framework is designed to operate seamlessly on embedded systems, ensuring robust performance in real-world applications. Extensive experiments using real-world datasets demonstrate that our model significantly outperforms existing methods, providing a scalable solution for ITS and ADAS applications. This research contributes to the advancement of Artificial Intelligence-driven (AI-driven) pattern recognition in transportation systems and offers a mathematical approach to improving efficiency and safety in logistics and transportation networks.展开更多
Large-scale damming has emerged as a prevalent global trend,significantly impacting nutrient transport and transformation,as well as the downstream ecological environment.Nitrogen and phosphorus are fundamental elemen...Large-scale damming has emerged as a prevalent global trend,significantly impacting nutrient transport and transformation,as well as the downstream ecological environment.Nitrogen and phosphorus are fundamental elements of primary productivity in aquatic ecosystems and serve as key limiting factors in reservoir eutrophication.This review focuses on the impact of damming on the transport and transformation of nitrogen and phosphorus,regarding changes in nutrient concentrations,fluxes,and proportions.Spatial changes in nitrogen and phosphorus concentrations primarily occur at the inlet and outlet of reservoirs,while temporal changes often exhibit seasonal patterns.At a global scale,phosphorus is preferentially removed from reservoirs compared to nitrogen.The factors influencing the transport and transformation processes of nitrogen and phosphorus in reservoirs include the physicochemical properties of water bodies and human activities.Additionally,nitrogen dynamics are affected by reservoir age,storage capacity,and water storage regulation modes,whereas phosphorus dynamics are also influenced by hydrodynamic conditions.Finally,this review summarizes the impact of damming on the downstream ecological environment and outlines future research directions,providing theoretical support for the management of river–reservoir ecosystems and promoting the green and sustainable development of hydropower in the context of carbon peaking and carbon neutrality goals.展开更多
Recent advances in two-dimensional layered systems have greatly enriched electronic transport studies, particularly in inter-layer Coulomb drag research. Here, systematic transport measurements were conducted in graph...Recent advances in two-dimensional layered systems have greatly enriched electronic transport studies, particularly in inter-layer Coulomb drag research. Here, systematic transport measurements were conducted in graphene-based electronic double-layer structures, revealing giant yet reproducible drag fluctuations at cryogenic temperatures. These fluctuations' characteristics, including amplitude and peak/valley spacing, are mainly determined by the drag layer's carrier dynamics rather than the drive layer's, resulting in violation of the Onsager reciprocity relation. Notably, the drag fluctuations remain observable up to 35 K, far exceeding universal conductance fluctuations within individual layers. This suggests enhanced phase coherence in inter-layer drag compared to single-layer transport, as further confirmed by quantitative analysis of auto-correlation fields of fluctuations under magnetic fields. Our findings provide new insights into quantum interference effects and their interplay with Coulomb interactions in solids. The observations of significant drag fluctuations could potentially help address chaotic signals between nearby components in nanoscale devices.展开更多
Guided by the analysis of source-to-sink system,this study investigates the Paleogene Oligocene Lingshui Formation in the Qiongdongnan Basin by comparing the geological characterizes in land and sea areas and integrat...Guided by the analysis of source-to-sink system,this study investigates the Paleogene Oligocene Lingshui Formation in the Qiongdongnan Basin by comparing the geological characterizes in land and sea areas and integrating outcrop,core,drilling,logging and 3D seismic data,to systematically analyze the characteristics of the source,transport pathway,and sink during the deposition of Lingshui Formation,and reveal the patterns,controlling factors and petroleum geologic significance of the source-to-sink systems.The results are obtained in five aspects.First,during the fault-depression transition,the Qiongdongnan Basin received sediments from the provenances presenting as segments in east-west and zones in north-south,primarily with the Indosinian granites in the Shenhu Uplift in the east and the Yanshanian granites in the west.Overall,the sources are young in the southern and northern parts and old in the interior of the basin.Second,three types of sediment transport pathways are identified:paleo-valleys,fault troughs and trough-valley transitional zones.Third,based on differences in sediment supply modes,the unique source-to-sink systems during the fault-depression transition in marine rift basins are categorized into three types:exogenous,endogenous and composite.Fourth,the characteristics of these source-to-sink systems are primarily controlled by provenance,paleogeomorphology,and sea-level changes.Provenance lithology and scale dictated the composition and volume of sedimentary deposits.Paleogeomorphology influenced erosion intensity in the provenance and the development of paleodrainage systems,thereby affecting the distribution and types of sedimentary systems.Additionally,sea-level changes decided the extent of the provenance,but also regulated the sediment distribution patterns through oceanic processes such as waves and tides.Fifth,the exogenous source-to-sink systems may form large-scale reservoir bodies,the endogenous systems develop secondary pores due to presence of soluble minerals,and the composite systems demonstrate reservoir properties varying from area to area.展开更多
Micro-and nano-plastics,defined as plastic particles measuring≤5 mm,represent a class of contaminants of emerging concern.These particles are ubiquitous in aquatic environments,posing significant threats to both fres...Micro-and nano-plastics,defined as plastic particles measuring≤5 mm,represent a class of contaminants of emerging concern.These particles are ubiquitous in aquatic environments,posing significant threats to both freshwater and marine organisms.The accumulation of micro-and nanoplastics in aquatic biota can lead to physical harm and chemical hazards,as these particles can serve as vectors for transporting toxic substances.As the research community strives to understand the transport and fate of micro-and nano-plastics,as well as their ecotoxicological implications,the scope of research questions continues to broaden.In response to these developments,the Journal of Oceanology and Limnology has recently launched a special issue entitled“Micro-and nano-plastics:an emerging contaminant in marine and freshwater ecosystems.”展开更多
This paper focuses on the optimization of the evaluation index system for the value of transportation infrastructure assets.It analyzes the shortcomings of the current system and explores the directions for optimizing...This paper focuses on the optimization of the evaluation index system for the value of transportation infrastructure assets.It analyzes the shortcomings of the current system and explores the directions for optimizing the index system from the perspectives of functionality,economy,social impact,environmental impact,and sustainability.The paper also discusses the application of the optimized index system in practical evaluation and the measures to ensure its effectiveness.The research aims to enhance the evaluation mechanism for the value of transportation infrastructure assets,providing a more scientific basis for decision-making,addressing challenges in asset management,improving the level of asset management in transportation infrastructure,and meeting the demands of high-quality development in the transportation sector in the new era.展开更多
Space-division multiplexing(SDM)utilizing uncoupled multi-core fibers(MCF)is considered a promising candidate for nextgeneration high-speed optical transmission systems due to its huge capacity and low inter-core cros...Space-division multiplexing(SDM)utilizing uncoupled multi-core fibers(MCF)is considered a promising candidate for nextgeneration high-speed optical transmission systems due to its huge capacity and low inter-core crosstalk.In this paper,we demonstrate a realtime high-speed SDM transmission system over a field-deployed 7-core MCF cable using commercial 400 Gbit/s backbone optical transport network(OTN)transceivers and a network management system.The transceivers employ a high noise-tolerant quadrature phase shift keying(QPSK)modulation format with a 130 Gbaud rate,enabled by optoelectronic multi-chip module(OE-MCM)packaging.The network management system can effectively manage and monitor the performance of the 7-core SDM OTN system and promptly report failure events through alarms.Our field trial demonstrates the compatibility of uncoupled MCF with high-speed OTN transmission equipment and network management systems,supporting its future deployment in next-generation high-speed terrestrial cable transmission networks.展开更多
Heterocyclic compounds play an important role in organic hole transport materials(HTMs)for perovskite solar cells(PSCs).Herein,a series of linear D-π-D HTMs(O-CBz,S-CBz,SO_(2)-CBz)with different dibenzoheterocycles c...Heterocyclic compounds play an important role in organic hole transport materials(HTMs)for perovskite solar cells(PSCs).Herein,a series of linear D-π-D HTMs(O-CBz,S-CBz,SO_(2)-CBz)with different dibenzoheterocycles core(dibenzofuran,dibenzothiophene,dibenzothiophene sulfone)were designed and synthesized,and their applications in PSCs were investigated.The intrinsic properties(CV,UV-vis,hole mobility and conductivity)were systematically investigated,demonstrating that all three materials are suitable HTMs for planar n-i-p type PSCs.Benefiting from the excellent hole mobility and conductivity,good film forming ability,and outstanding charge extraction and transport capability of S-CBz,FAPbI_(3)-based PSCs using S-CBz as HTM achieved a PCE of 25.0%,which is superior to that of Spiro-OMeTAD-based PSCs fabricated under the same conditions(23.9%).Furthermore,due to the interaction between S and Pb^(2+),SCBz-based PSC devices exhibited improved stability.This work demonstrates that dibenzothiophene-based architectures are promising candidates for high-performance HTMs in perovskite solar cell architectures.展开更多
With the integration of informatization and intelligence into the Communication-Based Train Control(CBTC)systems,the system is facing an increasing number of information security threats.As an important method of char...With the integration of informatization and intelligence into the Communication-Based Train Control(CBTC)systems,the system is facing an increasing number of information security threats.As an important method of characterizing the system security status,the security situation assessment is used to analyze the system security situation.However,existing situation assessment methods fail to integrate the coupling relationship between the physical layer and the information layer of the CBTC systems,and cannot dynamically characterize the real-time security situation changes under cyber attacks.In this paper,a hierarchical security situation assessment approach is proposed to address the security challenges of CBTC systems,which can perceive cyber attacks,quantify the security situation,and characterize the security situation changes under cyber attacks.Specifically,for the physical layer ofCBTC systems,the impact of cyber attacks is evaluated with the train punctuality rate and train departure interval indicators.For the information layer of CBTC systems,the system vulnerabilities and system threats are selected as static level indicators,and the critical network characteristics are selected as dynamic level indicators to quantify the real-time security situation.Finally,the comprehensive security situation assessment value of the CBTC systems is obtained by integrating the physical and information layer indicators.Simulation results illustrate that the proposed approach can dynamically characterize the real-time security situation of CBTC systems,enhancing the ability to perceive and assess information security risks.展开更多
The utilization of unmanned aerial vehicle(UAV) relays in cooperative communication has gained considerable attention in recent years.However,the current research is mostly based on fixed base stations and users,lacki...The utilization of unmanned aerial vehicle(UAV) relays in cooperative communication has gained considerable attention in recent years.However,the current research is mostly based on fixed base stations and users,lacking sufficient exploration of scenarios where communication nodes are in motion.This paper presents a multi-destination vehicle communication system based on decode-and-forward(DF)UAV relays,where source and destination vehicles are moving and an internal eavesdropper intercepts messages from UAV.The closed-form expressions for system outage probability and secrecy outage probability are derived to analyze the reliability and security of the system.Furthermore,the impact of the UAV's position,signal transmission power,and system time allocation ratio on the system's performance are also analyzed.The numerical simulation results validate the accuracy of the derived formulas and confirm the correctness of the analysis.The appropriate time allocation ratio significantly enhances the security performance of system under various environmental conditions.展开更多
Digital Twin (DT) technology is revolutionizing the railway sector by providing a virtual replica of physical systems, enabling real-time monitoring, predictive maintenance, and enhanced decision-making. This systemat...Digital Twin (DT) technology is revolutionizing the railway sector by providing a virtual replica of physical systems, enabling real-time monitoring, predictive maintenance, and enhanced decision-making. This systematic literature review examines the status, enabling technologies, case studies, and frameworks for DT applications in railway systems with 91 selected papers from Scopus, Web of Science, IEEE, and the Snowballing Technique. The review focuses on four primary subsystems: tracks, civil structures, vehicles, and overhead contact line structures. Key findings reveal that DT has successfully optimized maintenance strategies, improved operational efficiency, and enhanced system safety. Internet of Things (IoT) devices, Artificial Intelligence (AI), machine learning, and cloud computing are critical in implementing DT models. However, challenges like data integration, high implementation costs, and cybersecurity risks remain, necessitating the discussed implications. Future research should focus on improving data interoperability, reducing costs through scalable cloud-based solutions, and addressing cybersecurity vulnerabilities. DT technology has the potential to revolutionize railway infrastructure management, ensuring greater efficiency, safety, and sustainability.展开更多
Terahertz(THz)radiation possesses unique properties that make it a promising light source for applications in various fields,particularly spectroscopy and imaging.Ongoing research and development in THz technology has...Terahertz(THz)radiation possesses unique properties that make it a promising light source for applications in various fields,particularly spectroscopy and imaging.Ongoing research and development in THz technology has focused on developing or improving THz sources,detectors,and applications.At the PBP-CMU Electron Linac Laboratory(PCELL)of the Plasma and Beam Physics Research Facility in Chiang Mai University,high-intensity THz radiation has been generated in the form of coherent transition radiation(TR)and investigated since 2006 for electron beams with energies ranging from 8 to 12 MeV.In this study,we investigate and optimize the coherent TR arising from short electron bunches with energies ranging from 8 to 22 MeV using an upgraded linear-accelerator system with a higher radio-frequency(RF)power system.This radiation is then transported from the accelerator hall to the experimental room,in which the spectrometers are located.Electron-beam simulations are conducted to achieve short bunch lengths and small transverse beam sizes at the TR station.Radiation properties,including the radiation spectrum,angular distribution,and radiation polarization,are thoroughly investigated.The electron-bunch length is evaluated using the measuring system.The radiation-transport line is designed to achieve optimal frequency response and high transmission efficiency.A radiation-transmission efficiency of approximately 80-90%can be achieved with this designed system,along with a pulse energy ranging from 0.17 to 0.25μJ.The expected radiation spectral range covers up to 2 THz with a peak power of 0.5-1.25 MW.This coherent,broadband,and intense THz radiation will serve as a light source for THz spectroscopy and THz time-domain spectroscopy applications at the PCELL in the near future.展开更多
This article presents a comprehensive framework for advancing sustainable transportation through the integration of next-generation energy technologies.It explores the convergence of Vernova green energy,nuclear fissi...This article presents a comprehensive framework for advancing sustainable transportation through the integration of next-generation energy technologies.It explores the convergence of Vernova green energy,nuclear fission from ARCs(advanced reactor concepts)and SMRs(small modular reactors),and future-focused nuclear fusion methods-MCF(magnetic confinement fusion)and ICF(inertial confinement fusion).Central to this integration is the use of AI(artificial intelligence)to enhance smart grid efficiency,enable real-time optimization,and ensure resilient energy delivery.The synergy between these zero-carbon energy sources and AI-driven infrastructure promises a transformative impact on electric mobility,hydrogen-powered systems,and autonomous transport.By detailing the architecture of an AI-augmented,carbon-neutral transport ecosystem,this paper contributes to the roadmap for future global mobility.展开更多
The Intelligent Transportation System(ITS),as a vital means to alleviate traffic congestion and reduce traffic accidents,demonstrates immense potential in improving traffic safety and efficiency through the integratio...The Intelligent Transportation System(ITS),as a vital means to alleviate traffic congestion and reduce traffic accidents,demonstrates immense potential in improving traffic safety and efficiency through the integration of Internet of Things(IoT)technologies.The enhancement of its performance largely depends on breakthrough advancements in object detection technology.However,current object detection technology still faces numerous challenges,such as accuracy,robustness,and data privacy issues.These challenges are particularly critical in the application of ITS and require in-depth analysis and exploration of future improvement directions.This study provides a comprehensive review of the development of object detection technology and analyzes its specific applications in ITS,aiming to thoroughly explore the use and advancement of object detection technologies in IoT-based intelligent transportation systems.To achieve this objective,we adopted the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)approach to search,screen,and assess the eligibility of relevant literature,ultimately including 88 studies.Through an analysis of these studies,we summarized the characteristics,advantages,and limitations of object detection technology across the traditional methods stage and the deep learning-based methods stage.Additionally,we examined its applications in ITS from three perspectives:vehicle detection,pedestrian detection,and traffic sign detection.We also identified the major challenges currently faced by these technologies and proposed future directions for addressing these issues.This review offers researchers a comprehensive perspective,identifying potential improvement directions for object detection technology in ITS,including accuracy,robustness,real-time performance,data annotation cost,and data privacy.In doing so,it provides significant guidance for the further development of IoT-based intelligent transportation systems.展开更多
基金Project(50975290) supported by the National Natural Science Foundation of ChinaProject(2011QNZT057) supported by the Basic Operational Cost of Special Research Funding of Central Universities in ChinaProject(11JJ5028) supported by Hunan Provincial Natural Science Foundation,China
文摘As a solution to the breaking of pipeline under high axial force,carbon fiber composite pipe with low density and high intensity is applied to deep-sea mining transporting system.Based on the fact that the transporting pipe is under the forces of gravity,inner liquid,buoyancy as well as hydrodynamic force,geometric nonlinear finite element theory has been applied to analyzing the transporting system.Conclusions can be drawn as follows.Under the interaction of waves and currents,node forces FX and FZ acted by the transporting pipe on the mining vehicle are less than 2 kN,which indicates that waves and currents have little influence on the spatial shape of the transporting pipe and the mining vehicle movement.On the other hand,the horizontal force acting on the mining ship could be as large as 106 830 N,which has great influence on the mining system.
文摘The paper was a truck transporting system that based on system engineering theory and driver, truck-and-train, road and transporting environment were essential factors. It analyzed andstudied nine subsystems consisted of the tfour tactors, ensured running safety, high efficieney and lowconsumption of transporting truck and increased using time of truck and road.
文摘The mechanism of the nonlinear concentration dependence of the intestinal absorption of fluorescein isothiocyanate dextran 4,000 (FD-4) was studied using in situ rat intestinal loops and the in vitro Ussing-type chamber method. The intestinal absorption rate constant of FD-4, as evaluated by the intestinal loop method, increased significantly in a nonlinear fashion as the FD-4 concentration increased up to 0.2 mM and tended to decrease at concentrations higher than 0.2 mM. The mucosal-to-serosal permeation of FD-4 across rat ileal sheets, as evaluated by the in vitro Ussing-type chamber method, also increased in a nonlinear fashion in the low concentration range (0.01 - 0.02 mM), before decreasing as the concentration increased further, whereas serosal-to-mucosal permeation decreased in a concentration-dependent manner. In addition, mucosal-to-serosal flux and serosal-to-mucosal flux were increased and reduced in the presence of the metabolic inhibitor 2, 4-dinitrophenol, respectively. These results suggest that FD-4 is predominantly secreted into the intestinal lumen by an efflux transport system.
基金supported by the National Natural Science Foundation of China(Nos.42007178 and 41907327)the Natural Science Foundation of Hubei(Nos.2020CFB463 and 2019CFB372)+4 种基金China Geological Survey(Nos.DD20160304 and DD20190824)Fundamental Research Funds for the Central Universities(Nos.CUG 190644 and CUGL180817)National Key Research and Development Program(No.2019YFC1805502)Key Laboratory of Karst Dynamics,MNR and GZAR(Institute of Karst Geology,CAGS)Guilin(No.KDL201703)Key Laboratory of Karst Ecosystem and Treatment of Rocky Desertification,MNR and IRCK by UNESCO(No.KDL201903)。
文摘To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migongquan(MGQ))in Sixi valley,western Hubei,China.Highresolution continuous monitoring was utilized to obtain breakthrough curves(BTCs),which were then analyzed using the multi-dispersion model(MDM)and the two-region nonequilibrium model(2RNE)with basic parameters calculated by CXTFIT and QTRACER2.Results showed that:(1)YQD flow system had a complex infiltration matrix with overland flow,conduit flow and fracture flow,while the MGQ flow system was dominated by conduit flow with fast flow transport velocity,but also small amount of fracture flow there;(2)They were well fitted based on the MDM(R^2=0.928)and 2RNE(R^2=0.947)models,indicating that they had strong adaptability in the karst trough zone;(3)conceptual models for YQD and MGQ groundwater systems were generalized.In YQD system,the solute was transported via overland flow during intense rainfall,while some infiltrated down into fissures and conduits.In MGQ system,most were directly transported to spring outlet in the fissureconduit network.
基金supported by the Deanship of Scientific Research and Graduate Studies at King Khalid University under research grant number(R.G.P.2/93/45).
文摘Thedeployment of the Internet of Things(IoT)with smart sensors has facilitated the emergence of fog computing as an important technology for delivering services to smart environments such as campuses,smart cities,and smart transportation systems.Fog computing tackles a range of challenges,including processing,storage,bandwidth,latency,and reliability,by locally distributing secure information through end nodes.Consisting of endpoints,fog nodes,and back-end cloud infrastructure,it provides advanced capabilities beyond traditional cloud computing.In smart environments,particularly within smart city transportation systems,the abundance of devices and nodes poses significant challenges related to power consumption and system reliability.To address the challenges of latency,energy consumption,and fault tolerance in these environments,this paper proposes a latency-aware,faulttolerant framework for resource scheduling and data management,referred to as the FORD framework,for smart cities in fog environments.This framework is designed to meet the demands of time-sensitive applications,such as those in smart transportation systems.The FORD framework incorporates latency-aware resource scheduling to optimize task execution in smart city environments,leveraging resources from both fog and cloud environments.Through simulation-based executions,tasks are allocated to the nearest available nodes with minimum latency.In the event of execution failure,a fault-tolerantmechanism is employed to ensure the successful completion of tasks.Upon successful execution,data is efficiently stored in the cloud data center,ensuring data integrity and reliability within the smart city ecosystem.
基金Project supported by the Science and Technology Support Plan for Youth Innovation of Colleges and Universities of Shandong Province of China(No.2023KJ215)the National Natural Science Foundation of China(Nos.12002142 and 52405274)the National Natural Science Foundation of Shanghai of China(No.ZR2023QE100)。
文摘In industrial applications,plate-like structures such as steel strips in continuous hot-dip galvanizing and papers under fan action are ubiquitous.The vibration issues that arise when these structures are in axial motion,and are influenced by fluids and thermal fields,have attracted significant attention from the academic community.This study focuses on the nonlinear dynamic behavior of axially transporting immersed viscoelastic plates with particular emphasis on internal resonance and speed-dependent tension.The governing equation and the related boundary conditions for the axially transporting viscoelastic immersed plate are derived with Hamilton's principle,prioritizing the impact of time-varying tension induced by speed perturbations.Based on the second-order Galerkin truncation,the governing equation is discretized into a system of second-order ordinary differential equations.The multi-scale method is used to analyze the stable steady-state response of the immersed viscoelastic plate.The conditions for achieving a 3:1 frequency ratio between the first two orders of the system are analytically deduced.Notably,when the viscoelastic coefficient diminishes,the stability boundaries exhibit increased complexity,manifesting as the irregular W-shaped contours in the parameter space.Numerical examples comprehensively investigate the effects of viscoelasticity on both the stability region and the steady-state response under internal resonance conditions.Finally,the accuracy of the obtained results is validated through numerical computation.
基金funded by the Deanship of Scientific Research at Northern Border University,Arar,Saudi Arabia through research group No.(RG-NBU-2022-1234).
文摘Transportation systems are experiencing a significant transformation due to the integration of advanced technologies, including artificial intelligence and machine learning. In the context of intelligent transportation systems (ITS) and Advanced Driver Assistance Systems (ADAS), the development of efficient and reliable traffic light detection mechanisms is crucial for enhancing road safety and traffic management. This paper presents an optimized convolutional neural network (CNN) framework designed to detect traffic lights in real-time within complex urban environments. Leveraging multi-scale pyramid feature maps, the proposed model addresses key challenges such as the detection of small, occluded, and low-resolution traffic lights amidst complex backgrounds. The integration of dilated convolutions, Region of Interest (ROI) alignment, and Soft Non-Maximum Suppression (Soft-NMS) further improves detection accuracy and reduces false positives. By optimizing computational efficiency and parameter complexity, the framework is designed to operate seamlessly on embedded systems, ensuring robust performance in real-world applications. Extensive experiments using real-world datasets demonstrate that our model significantly outperforms existing methods, providing a scalable solution for ITS and ADAS applications. This research contributes to the advancement of Artificial Intelligence-driven (AI-driven) pattern recognition in transportation systems and offers a mathematical approach to improving efficiency and safety in logistics and transportation networks.
基金supported by the General Project of the National Natural Science Foundation of China(Grant No.42377054)the National Natural Science Fund for Young Scholars(Grant No.42007149)the Key Project of the Major Research Plan of the National Natural Science Foundation of China(Grant No.92047201).
文摘Large-scale damming has emerged as a prevalent global trend,significantly impacting nutrient transport and transformation,as well as the downstream ecological environment.Nitrogen and phosphorus are fundamental elements of primary productivity in aquatic ecosystems and serve as key limiting factors in reservoir eutrophication.This review focuses on the impact of damming on the transport and transformation of nitrogen and phosphorus,regarding changes in nutrient concentrations,fluxes,and proportions.Spatial changes in nitrogen and phosphorus concentrations primarily occur at the inlet and outlet of reservoirs,while temporal changes often exhibit seasonal patterns.At a global scale,phosphorus is preferentially removed from reservoirs compared to nitrogen.The factors influencing the transport and transformation processes of nitrogen and phosphorus in reservoirs include the physicochemical properties of water bodies and human activities.Additionally,nitrogen dynamics are affected by reservoir age,storage capacity,and water storage regulation modes,whereas phosphorus dynamics are also influenced by hydrodynamic conditions.Finally,this review summarizes the impact of damming on the downstream ecological environment and outlines future research directions,providing theoretical support for the management of river–reservoir ecosystems and promoting the green and sustainable development of hydropower in the context of carbon peaking and carbon neutrality goals.
基金supported by the National Natural Science Foundation of China (Grant Nos.12474051 and 92165201)the Chinese Academy of Sciences Project for Young Scientists in Basic Research (Grant No.YSBR-046)+1 种基金the National Key Research and Development Program of China (Grant No.2023YFA1406300)the Anhui Provincial Natural Science Foundation (Grant Nos.2308085J11 and2308085QA14)。
文摘Recent advances in two-dimensional layered systems have greatly enriched electronic transport studies, particularly in inter-layer Coulomb drag research. Here, systematic transport measurements were conducted in graphene-based electronic double-layer structures, revealing giant yet reproducible drag fluctuations at cryogenic temperatures. These fluctuations' characteristics, including amplitude and peak/valley spacing, are mainly determined by the drag layer's carrier dynamics rather than the drive layer's, resulting in violation of the Onsager reciprocity relation. Notably, the drag fluctuations remain observable up to 35 K, far exceeding universal conductance fluctuations within individual layers. This suggests enhanced phase coherence in inter-layer drag compared to single-layer transport, as further confirmed by quantitative analysis of auto-correlation fields of fluctuations under magnetic fields. Our findings provide new insights into quantum interference effects and their interplay with Coulomb interactions in solids. The observations of significant drag fluctuations could potentially help address chaotic signals between nearby components in nanoscale devices.
基金Supported by National Natural Science Foundation of China Enterprise Joint Fund Project(U24B200849)National Natural Science Foundation of China(91528303).
文摘Guided by the analysis of source-to-sink system,this study investigates the Paleogene Oligocene Lingshui Formation in the Qiongdongnan Basin by comparing the geological characterizes in land and sea areas and integrating outcrop,core,drilling,logging and 3D seismic data,to systematically analyze the characteristics of the source,transport pathway,and sink during the deposition of Lingshui Formation,and reveal the patterns,controlling factors and petroleum geologic significance of the source-to-sink systems.The results are obtained in five aspects.First,during the fault-depression transition,the Qiongdongnan Basin received sediments from the provenances presenting as segments in east-west and zones in north-south,primarily with the Indosinian granites in the Shenhu Uplift in the east and the Yanshanian granites in the west.Overall,the sources are young in the southern and northern parts and old in the interior of the basin.Second,three types of sediment transport pathways are identified:paleo-valleys,fault troughs and trough-valley transitional zones.Third,based on differences in sediment supply modes,the unique source-to-sink systems during the fault-depression transition in marine rift basins are categorized into three types:exogenous,endogenous and composite.Fourth,the characteristics of these source-to-sink systems are primarily controlled by provenance,paleogeomorphology,and sea-level changes.Provenance lithology and scale dictated the composition and volume of sedimentary deposits.Paleogeomorphology influenced erosion intensity in the provenance and the development of paleodrainage systems,thereby affecting the distribution and types of sedimentary systems.Additionally,sea-level changes decided the extent of the provenance,but also regulated the sediment distribution patterns through oceanic processes such as waves and tides.Fifth,the exogenous source-to-sink systems may form large-scale reservoir bodies,the endogenous systems develop secondary pores due to presence of soluble minerals,and the composite systems demonstrate reservoir properties varying from area to area.
基金Supported by the Natural Science Key Foundation of Fujian Province,China(No.2020J02002)the Hainan Province Science and Technology Special Fund(No.ZDYF2022SHFZ317)。
文摘Micro-and nano-plastics,defined as plastic particles measuring≤5 mm,represent a class of contaminants of emerging concern.These particles are ubiquitous in aquatic environments,posing significant threats to both freshwater and marine organisms.The accumulation of micro-and nanoplastics in aquatic biota can lead to physical harm and chemical hazards,as these particles can serve as vectors for transporting toxic substances.As the research community strives to understand the transport and fate of micro-and nano-plastics,as well as their ecotoxicological implications,the scope of research questions continues to broaden.In response to these developments,the Journal of Oceanology and Limnology has recently launched a special issue entitled“Micro-and nano-plastics:an emerging contaminant in marine and freshwater ecosystems.”
文摘This paper focuses on the optimization of the evaluation index system for the value of transportation infrastructure assets.It analyzes the shortcomings of the current system and explores the directions for optimizing the index system from the perspectives of functionality,economy,social impact,environmental impact,and sustainability.The paper also discusses the application of the optimized index system in practical evaluation and the measures to ensure its effectiveness.The research aims to enhance the evaluation mechanism for the value of transportation infrastructure assets,providing a more scientific basis for decision-making,addressing challenges in asset management,improving the level of asset management in transportation infrastructure,and meeting the demands of high-quality development in the transportation sector in the new era.
文摘Space-division multiplexing(SDM)utilizing uncoupled multi-core fibers(MCF)is considered a promising candidate for nextgeneration high-speed optical transmission systems due to its huge capacity and low inter-core crosstalk.In this paper,we demonstrate a realtime high-speed SDM transmission system over a field-deployed 7-core MCF cable using commercial 400 Gbit/s backbone optical transport network(OTN)transceivers and a network management system.The transceivers employ a high noise-tolerant quadrature phase shift keying(QPSK)modulation format with a 130 Gbaud rate,enabled by optoelectronic multi-chip module(OE-MCM)packaging.The network management system can effectively manage and monitor the performance of the 7-core SDM OTN system and promptly report failure events through alarms.Our field trial demonstrates the compatibility of uncoupled MCF with high-speed OTN transmission equipment and network management systems,supporting its future deployment in next-generation high-speed terrestrial cable transmission networks.
基金supported by the financial support from the National Natural Science Foundation of China(Nos.22279046,22179053)Natural Science Excellent Youth Foundation of Jiangsu Province(No.BK20220112)Special Foundation for Carbon Peak Carbon Neutralization Technology Innovation Program of Jiangsu Province(No.BE2022026-2).
文摘Heterocyclic compounds play an important role in organic hole transport materials(HTMs)for perovskite solar cells(PSCs).Herein,a series of linear D-π-D HTMs(O-CBz,S-CBz,SO_(2)-CBz)with different dibenzoheterocycles core(dibenzofuran,dibenzothiophene,dibenzothiophene sulfone)were designed and synthesized,and their applications in PSCs were investigated.The intrinsic properties(CV,UV-vis,hole mobility and conductivity)were systematically investigated,demonstrating that all three materials are suitable HTMs for planar n-i-p type PSCs.Benefiting from the excellent hole mobility and conductivity,good film forming ability,and outstanding charge extraction and transport capability of S-CBz,FAPbI_(3)-based PSCs using S-CBz as HTM achieved a PCE of 25.0%,which is superior to that of Spiro-OMeTAD-based PSCs fabricated under the same conditions(23.9%).Furthermore,due to the interaction between S and Pb^(2+),SCBz-based PSC devices exhibited improved stability.This work demonstrates that dibenzothiophene-based architectures are promising candidates for high-performance HTMs in perovskite solar cell architectures.
基金supported in part by the project of the State Key Laboratory of Advanced Rail Autonomous Operation(RAO2023ZZ004)in part by the Beijing Natural Science Foundation-Fengtai Rail Transit Frontier Research Joint Fund(L211002)+2 种基金in part by the Foundation of China State Railway Group Corporation Limited under Grant L2021G003in part by the Scientific and Technical Research Fund of China Academy of Railway Sciences Corporation Limited under Grant 2021YJ094in part by the Project I23L00200 and Project I24F00010.
文摘With the integration of informatization and intelligence into the Communication-Based Train Control(CBTC)systems,the system is facing an increasing number of information security threats.As an important method of characterizing the system security status,the security situation assessment is used to analyze the system security situation.However,existing situation assessment methods fail to integrate the coupling relationship between the physical layer and the information layer of the CBTC systems,and cannot dynamically characterize the real-time security situation changes under cyber attacks.In this paper,a hierarchical security situation assessment approach is proposed to address the security challenges of CBTC systems,which can perceive cyber attacks,quantify the security situation,and characterize the security situation changes under cyber attacks.Specifically,for the physical layer ofCBTC systems,the impact of cyber attacks is evaluated with the train punctuality rate and train departure interval indicators.For the information layer of CBTC systems,the system vulnerabilities and system threats are selected as static level indicators,and the critical network characteristics are selected as dynamic level indicators to quantify the real-time security situation.Finally,the comprehensive security situation assessment value of the CBTC systems is obtained by integrating the physical and information layer indicators.Simulation results illustrate that the proposed approach can dynamically characterize the real-time security situation of CBTC systems,enhancing the ability to perceive and assess information security risks.
基金supported by the National Natural Science Foundation of China under Grants 62001359 and 61901201by the Key Science and Technology Research Project of Henan Province under Grants 232102211059the Natural Science Basic Research Program of Shaanxi under Grants 2022JQ-658 and 2022JQ-621。
文摘The utilization of unmanned aerial vehicle(UAV) relays in cooperative communication has gained considerable attention in recent years.However,the current research is mostly based on fixed base stations and users,lacking sufficient exploration of scenarios where communication nodes are in motion.This paper presents a multi-destination vehicle communication system based on decode-and-forward(DF)UAV relays,where source and destination vehicles are moving and an internal eavesdropper intercepts messages from UAV.The closed-form expressions for system outage probability and secrecy outage probability are derived to analyze the reliability and security of the system.Furthermore,the impact of the UAV's position,signal transmission power,and system time allocation ratio on the system's performance are also analyzed.The numerical simulation results validate the accuracy of the derived formulas and confirm the correctness of the analysis.The appropriate time allocation ratio significantly enhances the security performance of system under various environmental conditions.
文摘Digital Twin (DT) technology is revolutionizing the railway sector by providing a virtual replica of physical systems, enabling real-time monitoring, predictive maintenance, and enhanced decision-making. This systematic literature review examines the status, enabling technologies, case studies, and frameworks for DT applications in railway systems with 91 selected papers from Scopus, Web of Science, IEEE, and the Snowballing Technique. The review focuses on four primary subsystems: tracks, civil structures, vehicles, and overhead contact line structures. Key findings reveal that DT has successfully optimized maintenance strategies, improved operational efficiency, and enhanced system safety. Internet of Things (IoT) devices, Artificial Intelligence (AI), machine learning, and cloud computing are critical in implementing DT models. However, challenges like data integration, high implementation costs, and cybersecurity risks remain, necessitating the discussed implications. Future research should focus on improving data interoperability, reducing costs through scalable cloud-based solutions, and addressing cybersecurity vulnerabilities. DT technology has the potential to revolutionize railway infrastructure management, ensuring greater efficiency, safety, and sustainability.
基金supported by the National Research Council of Thailand(No.NRCT-5-RSA63004-16)Chiang Mai University.S.Pakluea acknowledges scholarship support from the Science Achievement Scholarship of Thailand(SAST).
文摘Terahertz(THz)radiation possesses unique properties that make it a promising light source for applications in various fields,particularly spectroscopy and imaging.Ongoing research and development in THz technology has focused on developing or improving THz sources,detectors,and applications.At the PBP-CMU Electron Linac Laboratory(PCELL)of the Plasma and Beam Physics Research Facility in Chiang Mai University,high-intensity THz radiation has been generated in the form of coherent transition radiation(TR)and investigated since 2006 for electron beams with energies ranging from 8 to 12 MeV.In this study,we investigate and optimize the coherent TR arising from short electron bunches with energies ranging from 8 to 22 MeV using an upgraded linear-accelerator system with a higher radio-frequency(RF)power system.This radiation is then transported from the accelerator hall to the experimental room,in which the spectrometers are located.Electron-beam simulations are conducted to achieve short bunch lengths and small transverse beam sizes at the TR station.Radiation properties,including the radiation spectrum,angular distribution,and radiation polarization,are thoroughly investigated.The electron-bunch length is evaluated using the measuring system.The radiation-transport line is designed to achieve optimal frequency response and high transmission efficiency.A radiation-transmission efficiency of approximately 80-90%can be achieved with this designed system,along with a pulse energy ranging from 0.17 to 0.25μJ.The expected radiation spectral range covers up to 2 THz with a peak power of 0.5-1.25 MW.This coherent,broadband,and intense THz radiation will serve as a light source for THz spectroscopy and THz time-domain spectroscopy applications at the PCELL in the near future.
文摘This article presents a comprehensive framework for advancing sustainable transportation through the integration of next-generation energy technologies.It explores the convergence of Vernova green energy,nuclear fission from ARCs(advanced reactor concepts)and SMRs(small modular reactors),and future-focused nuclear fusion methods-MCF(magnetic confinement fusion)and ICF(inertial confinement fusion).Central to this integration is the use of AI(artificial intelligence)to enhance smart grid efficiency,enable real-time optimization,and ensure resilient energy delivery.The synergy between these zero-carbon energy sources and AI-driven infrastructure promises a transformative impact on electric mobility,hydrogen-powered systems,and autonomous transport.By detailing the architecture of an AI-augmented,carbon-neutral transport ecosystem,this paper contributes to the roadmap for future global mobility.
文摘The Intelligent Transportation System(ITS),as a vital means to alleviate traffic congestion and reduce traffic accidents,demonstrates immense potential in improving traffic safety and efficiency through the integration of Internet of Things(IoT)technologies.The enhancement of its performance largely depends on breakthrough advancements in object detection technology.However,current object detection technology still faces numerous challenges,such as accuracy,robustness,and data privacy issues.These challenges are particularly critical in the application of ITS and require in-depth analysis and exploration of future improvement directions.This study provides a comprehensive review of the development of object detection technology and analyzes its specific applications in ITS,aiming to thoroughly explore the use and advancement of object detection technologies in IoT-based intelligent transportation systems.To achieve this objective,we adopted the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)approach to search,screen,and assess the eligibility of relevant literature,ultimately including 88 studies.Through an analysis of these studies,we summarized the characteristics,advantages,and limitations of object detection technology across the traditional methods stage and the deep learning-based methods stage.Additionally,we examined its applications in ITS from three perspectives:vehicle detection,pedestrian detection,and traffic sign detection.We also identified the major challenges currently faced by these technologies and proposed future directions for addressing these issues.This review offers researchers a comprehensive perspective,identifying potential improvement directions for object detection technology in ITS,including accuracy,robustness,real-time performance,data annotation cost,and data privacy.In doing so,it provides significant guidance for the further development of IoT-based intelligent transportation systems.
