期刊文献+
共找到42,182篇文章
< 1 2 250 >
每页显示 20 50 100
Multi-period mine planning with multi-process routes 被引量:7
1
作者 Mustafa Kumral 《International Journal of Mining Science and Technology》 SCIE EI 2013年第3期317-321,共5页
This paper attempts to optimize optimal capacities, block routing and mine sequencing problems in a mining system. The solution approach is based on a heuristics and the mixed integer programming (MIP). Unlike previou... This paper attempts to optimize optimal capacities, block routing and mine sequencing problems in a mining system. The solution approach is based on a heuristics and the mixed integer programming (MIP). Unlike previous sequential solution approaches, the problems are herein solved at the same time. Furthermore, the proposed approach guarantees practical solutions because it considers ore material distribution within orebody. The paper has two main contributions: (a) the proposed approach generates production rates in a manner that the capacities are satisfied; (b) the proposed approach does not use pre-defined marginal cut-off grades. Thus, idle capacity problem is eliminated and different scheduling combinations are allowed. To see the performance of the approach proposed, a case study is carried out using a gold data. The schedule generated shows that the approach can determine optimal production rates, block destination and sequencing effectively. 展开更多
关键词 Mine planning Multi-route Sequencing Production rates Heuristics Mixed integer programming
下载PDF
The Impact of Sea Level Rise on Roadway Design and Evacuation Routes in Delaware
2
作者 Jack Palevich Ardeshir Faghri Ahmet Karakurt 《American Journal of Climate Change》 2024年第1期69-82,共14页
As the global temperature continues to increase, the sea level continues to rise at a rapid rate that has never been seen before. This becomes an issue for many facets of life but one of the most impacted is the trans... As the global temperature continues to increase, the sea level continues to rise at a rapid rate that has never been seen before. This becomes an issue for many facets of life but one of the most impacted is the transportation infrastructure. Many people living in low elevation coastal areas can become trapped by flooding with no way in or out. With Delaware being a coastal state, this would affect a large portion of the population and will have detrimental effects over time if nothing is done to combat sea level rise. The issue with sea level rise in transportation is that once the roads become flooded, they become virtually unusable and detour routes would be needed. If all the roads in a coastal area were to be affected by sea level rise, the options for detours would become limited. This article looks at direct solutions to combat sea level rise and indirect solutions that would specifically help transportation infrastructure and evacuation routes in Delaware. There is not one solution that can fix every problem, so many solutions are laid out to see what is applicable to each affected area. Some solutions include defense structures that would be put close to the coast, raising the elevation of vulnerable roads throughout the state and including pumping stations to drain the water on the surface of the road. With an understanding of all these solutions around the world, the ultimate conclusion came in the form of a six-step plan that Delaware should take in order to best design against sea level rise in these coastal areas. 展开更多
关键词 Sea Level Rise Roadway Design Evacuation routes
下载PDF
Stage at diagnosis of colorectal cancer through diagnostic route:Who should be screened? 被引量:9
3
作者 Nobukazu Agatsuma Takahiro Utsumi +11 位作者 Yoshitaka Nishikawa Takahiro Horimatsu Takeshi Seta Yukitaka Yamashita Yukari Tanaka Takahiro Inoue Yuki Nakanishi Takahiro Shimizu Mikako Ohno Akane Fukushima Takeo Nakayama Hiroshi Seno 《World Journal of Gastroenterology》 SCIE CAS 2024年第10期1368-1376,共9页
BACKGROUND Colorectal cancer(CRC)is a global health concern,with advanced-stage diagnoses contributing to poor prognoses.The efficacy of CRC screening has been well-established;nevertheless,a significant proportion of... BACKGROUND Colorectal cancer(CRC)is a global health concern,with advanced-stage diagnoses contributing to poor prognoses.The efficacy of CRC screening has been well-established;nevertheless,a significant proportion of patients remain unscreened,with>70%of cases diagnosed outside screening.Although identifying specific subgroups for whom CRC screening should be particularly recommended is crucial owing to limited resources,the association between the diagnostic routes and identification of these subgroups has been less appreciated.In the Japanese cancer registry,the diagnostic routes for groups discovered outside of screening are primarily categorized into those with comorbidities found during hospital visits and those with CRC-related symptoms.AIM To clarify the stage at CRC diagnosis based on diagnostic routes.METHODS We conducted a retrospective observational study using a cancer registry of patients with CRC between January 2016 and December 2019 at two hospitals.The diagnostic routes were primarily classified into three groups:Cancer screening,follow-up,and symptomatic.The early-stage was defined as Stages 0 or I.Multivariate and univariate logistic regressions were exploited to determine the odds of early-stage diagnosis in the symptomatic and cancer screening groups,referencing the follow-up group.The adjusted covariates were age,sex,and tumor location.RESULTS Of the 2083 patients,715(34.4%),1064(51.1%),and 304(14.6%)belonged to the follow-up,symptomatic,and cancer screening groups,respectively.Among the 2083 patients,CRCs diagnosed at an early stage were 57.3%(410 of 715),23.9%(254 of 1064),and 59.5%(181 of 304)in the follow-up,symptomatic,and cancer screening groups,respectively.The symptomatic group exhibited a lower likelihood of early-stage diagnosis than the follow-up group[P<0.001,adjusted odds ratio(aOR),0.23;95%confidence interval(95%CI):0.19-0.29].The likelihood of diagnosis at an early stage was similar between the follow-up and cancer screening groups(P=0.493,aOR for early-stage diagnosis in the cancer screening group vs follow-up group=1.11;95%CI=0.82-1.49).CONCLUSION CRCs detected during hospital visits for comorbidities were diagnosed earlier,similar to cancer screening.CRC screening should be recommended,particularly for patients without periodical hospital visits for comorbidities. 展开更多
关键词 Colorectal neoplasms Cancer registry Diagnostic route Cancer screening Stage at diagnosis
下载PDF
Therapeutic Routes of a Group of Heart Failure Patients Followed in a Cameroonian Urban Setting
4
作者 Chris Nadège Nganou-Gnindjio Bâ Hamadou +8 位作者 Melissa Djuidje Djampouop Marie Ntep Gwet Félicité Kamdem Pierre Mintom Juliette Valerie Ndobo Siddikatou Djibrilla Guillaume Ebene Manon Joel Noutackdie Tochie Samuel Kingue 《World Journal of Cardiovascular Diseases》 2023年第10期686-700,共15页
Background: Heart failure (HF) is a rising global health problem. Patients with HF tend to use several therapies obtained via different treatment routes to relieve their symptoms. It is rampant in sub-Saharan Africa (... Background: Heart failure (HF) is a rising global health problem. Patients with HF tend to use several therapies obtained via different treatment routes to relieve their symptoms. It is rampant in sub-Saharan Africa (SSA), leading to poor health-seeking behaviours and worsened HF health outcomes. We aimed to describe the different therapeutic routes of HF patients from the onset of their first symptom until treatment in a specialised cardiology centre to identify and rebuke harmful therapeutic routes. Materials and Methods: This was a cross-sectional study at the Yaoundé Central Hospital in Cameroon between December 2018 to July 2019. Patients were recruited by consecutive convenient sampling. Adult patients aged above 18 years with confirmed HF were included using the Framingham criteria. Variables relating to socio-demographic and clinical data and the health-seeking behaviours of HF patients were studied. Results: We included 132 patients with a mean age of 62.90 years (62.88% women). Very few patients (0.90%) followed an ideal route;60.71% of subjects had a pseudo-ideal route, 19.64% accessed a specialised facility directly, and 21.42% used an erratic route. At the arrival time in a cardiology unit, 49.24% and 35.61% of our subjects were in NYHA stage III and IV HF compared to 15.15% for stage II. None of them was in Stage I. Conclusion: Most heart failure patients in Cameroon have resorted to non-specialised care, which worsens their clinical presentation. There is an urgent need for health education of HF patients in our context. 展开更多
关键词 Heart Failure Therapeutic Care route Cameroon
下载PDF
Migration routes and differences in migration strategies of Whooper Swans between spring and autumn
5
作者 Ji-Yeon Lee Hyung-Kyu Nam +10 位作者 Jin-Young Park Seung-Gu Kang Nyambayar Batbayar Dong-Won Kim Jae-Woong Hwang Otgonbayar Tsend Tseveenmyadag Natsagdorj Jugdernamjil Nergui Tuvshintugs Sukhbaatar Wee-Haeng Hur Jeong-Chil Yoo 《Avian Research》 SCIE CSCD 2023年第3期345-353,共9页
Long-distance migratory birds travel more rapidly in spring than in autumn,as they face temporal breeding constraints.However,several species travel slower in spring owing to environmental influences,such as food avai... Long-distance migratory birds travel more rapidly in spring than in autumn,as they face temporal breeding constraints.However,several species travel slower in spring owing to environmental influences,such as food availability and wind conditions.GPS trackers were attached to 17 Whooper Swans(Cygnus cygnus) inhabiting northeastern Mongolia,to determine their migration routes and stopover sites in spring and autumn.Differences between spring and autumn migrations,migration-influencing parameters,and the effect of spring stopover site temperatures were analyzed.Six swans completed perfect tours between their wintering and breeding sites,and these data were used for analysis.Spring migration lasted 57 days,with 49.2 days spent at 3.7 stopover sites.Autumn migration lasted 21.5 days,with 17.5 days spent at 1.0 stopover sites.Thus,the swans traveled more rapidly in autumn than in spring.Migration distance,number of stopovers,migration speed,and straightness were important migration determinants in both spring and autumn.Migration distance,stopover duration,number of stopovers,daily travel speed,travel duration,and migration speed differed significantly between spring and autumn.During spring migration,the temperature at the current stopover sites and that at the future stopover sites displayed significant variations(t=1585.8,df=631.6,p <0.001).These findings are critical for the conservation and management of Whooper Swans and their key habitats in East Asian regions,and the data are anticipated to make a particularly significant contribution toward developing detailed management plans for the conservation of their key habitats. 展开更多
关键词 Key stopover sites Migration characteristics Migration route Migration strategy Tracking Whooper Swan
下载PDF
Regional variation in routes to diagnosis of cholangiocarcinoma in England from 2006 to 2017
6
作者 Amy Zalin-Miller Sophie Jose +5 位作者 Craig Knott Lizz Paley Daniela Tataru Helen Morement Mireille B Toledano Shahid A Khan 《World Journal of Gastroenterology》 SCIE CAS 2023年第24期3825-3842,共18页
BACKGROUND Incidence of cholangiocarcinoma(CCA)is rising,with overall prognosis remaining very poor.Reasons for the high mortality of CCA include its late presentation in most patients,when curative options are no lon... BACKGROUND Incidence of cholangiocarcinoma(CCA)is rising,with overall prognosis remaining very poor.Reasons for the high mortality of CCA include its late presentation in most patients,when curative options are no longer feasible,and poor response to systemic therapies for advanced disease.Late presentation presents a large barrier to improving outcomes and is often associated with diagnosis via mergency presentation(EP).Earlier diagnoses may be made by Two Week Wait(TWW)referrals through General practitioner(GP).We hypothesise that TWW referrals and EP routes to diagnosis differ across regions in England.AIM To investigate routes to diagnosis of CCA over time,regional variation and influencing factors.METHODS We linked patient records from the National Cancer Registration Dataset to Hospital Episode Statistics,Cancer Waiting Times and Cancer Screening Programme datasets to define routes to diagnosis and certain patient characteristics for patients diagnosed 2006-2017 in England.We used linear probability models to investigate geographic variation by assessing the proportions of patients diagnosed via TWW referral or EP across Cancer Alliances in England,adjusting for potential confounders.Correlation between the proportion of people diagnosed by TWW referral and EP was investigated with Spearman’s correlation coefficient.RESULTS Of 23632 patients diagnosed between 2006-2017 in England,the most common route to diagnosis was EP(49.6%).Non-TWW GP referrals accounted for 20.5%of diagnosis routes,13.8%were diagnosed by TWW referral,and the remainder 16.2%were diagnosed via an‘other’or Unknown route.The proportion diagnosed via a TWW referral doubled between 2006-2017 rising from 9.9%to 19.8%,conversely EP diagnosis route declined,falling from 51.3%to 46.0%.Statistically significant variation in both the TWW referral and EP proportions was found across Cancer Alliances.Age,presence of comorbidity and underlying liver disease were independently associated with both a lower proportion of patients diagnosed via TWW referral,and a higher proportion diagnosed by EP after adjusting for other potential confounders.CONCLUSION There is significant geographic and socio-demographic variation in routes to diagnosis of CCA in England.Knowledge sharing of best practice may improve diagnostic pathways and reduce unwarranted variation. 展开更多
关键词 CHOLANGIOCARCINOMA route to diagnosis Two Week Wait Emergency presentation Regional variation
下载PDF
MTCR-CR Routing Strategy for Connection-Oriented Routing over Satellite Networks
7
作者 Li Changhao Sun Xue +1 位作者 Yan Lei Cao Suzhi 《China Communications》 SCIE CSCD 2024年第5期280-296,共17页
The high-speed movement of satellites makes it not feasible to directly apply the mature routing scheme on the ground to the satellite network.DT-DVTR in the snapshot-based connectionoriented routing strategy is one o... The high-speed movement of satellites makes it not feasible to directly apply the mature routing scheme on the ground to the satellite network.DT-DVTR in the snapshot-based connectionoriented routing strategy is one of the representative solutions,but it still has room for improvement in terms of routing stability.In this paper,we propose an improved scheme for connection-oriented routing strategy named the Minimal Topology Change Routing based on Collaborative Rules(MTCR-CR).The MTCR-CR uses continuous time static topology snapshots based on satellite status to search for intersatellite link(ISL)construction solutions that meet the minimum number of topology changes to avoid route oscillations.The simulation results in Beidou-3 show that compared with DT-DVTR,MTCR-CR reduces the number of routing changes by about 92%,the number of path changes caused by routing changes is about38%,and the rerouting time is reduced by approximately 47%.At the same time,in order to show our algorithm more comprehensively,the same experimental index test was also carried out on the Globalstar satellite constellation. 展开更多
关键词 ISL routing stability satellite networks satellite routing dynamic strategy
下载PDF
Efficient Route Planning for Real-Time Demand-Responsive Transit
8
作者 Hongle Li SeongKi Kim 《Computers, Materials & Continua》 SCIE EI 2024年第4期473-492,共20页
Demand Responsive Transit (DRT) responds to the dynamic users’ requests without any fixed routes and timetablesand determines the stop and the start according to the demands. This study explores the optimization of d... Demand Responsive Transit (DRT) responds to the dynamic users’ requests without any fixed routes and timetablesand determines the stop and the start according to the demands. This study explores the optimization of dynamicvehicle scheduling and real-time route planning in urban public transportation systems, with a focus on busservices. It addresses the limitations of current shared mobility routing algorithms, which are primarily designedfor simpler, single origin/destination scenarios, and do not meet the complex demands of bus transit systems. Theresearch introduces an route planning algorithm designed to dynamically accommodate passenger travel needsand enable real-time route modifications. Unlike traditional methods, this algorithm leverages a queue-based,multi-objective heuristic A∗ approach, offering a solution to the inflexibility and limited coverage of suburbanbus routes. Also, this study conducts a comparative analysis of the proposed algorithm with solutions based onGenetic Algorithm (GA) and Ant Colony Optimization Algorithm (ACO), focusing on calculation time, routelength, passenger waiting time, boarding time, and detour rate. The findings demonstrate that the proposedalgorithmsignificantly enhances route planning speed, achieving an 80–100-fold increase in efficiency over existingmodels, thereby supporting the real-time demands of Demand-Responsive Transportation (DRT) systems. Thestudy concludes that this algorithm not only optimizes route planning in bus transit but also presents a scalablesolution for improving urban mobility. 展开更多
关键词 Autonomous bus route planning real-time dynamic route planning path finding DRT bus route optimization sustainable public transport
下载PDF
CoopAI-Route: DRL Empowered Multi-Agent Cooperative System for Efficient QoS-Aware Routing for Network Slicing in Multi-Domain SDN
9
作者 Meignanamoorthi Dhandapani V.Vetriselvi R.Aishwarya 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第9期2449-2486,共38页
The emergence of beyond 5G networks has the potential for seamless and intelligent connectivity on a global scale.Network slicing is crucial in delivering services for different,demanding vertical applications in this... The emergence of beyond 5G networks has the potential for seamless and intelligent connectivity on a global scale.Network slicing is crucial in delivering services for different,demanding vertical applications in this context.Next-generation applications have time-sensitive requirements and depend on the most efficient routing path to ensure packets reach their intended destinations.However,the existing IP(Internet Protocol)over a multi-domain network faces challenges in enforcing network slicing due to minimal collaboration and information sharing among network operators.Conventional inter-domain routing methods,like Border Gateway Protocol(BGP),cannot make routing decisions based on performance,which frequently results in traffic flowing across congested paths that are never optimal.To address these issues,we propose CoopAI-Route,a multi-agent cooperative deep reinforcement learning(DRL)system utilizing hierarchical software-defined networks(SDN).This framework enforces network slicing in multi-domain networks and cooperative communication with various administrators to find performance-based routes in intra-and inter-domain.CoopAI-Route employs the Distributed Global Topology(DGT)algorithm to define inter-domain Quality of Service(QoS)paths.CoopAI-Route uses a DRL agent with a message-passing multi-agent Twin-Delayed Deep Deterministic Policy Gradient method to ensure optimal end-to-end routes adapted to the specific requirements of network slicing applications.Our evaluation demonstrates CoopAI-Route’s commendable performance in scalability,link failure handling,and adaptability to evolving topologies compared to state-of-the-art methods. 展开更多
关键词 6G MULTI-DOMAIN MULTI-AGENT routING DRL SDN
下载PDF
Enhancing Network Design through Statistical Evaluation of MANET Routing Protocols
10
作者 Ibrahim Alameri Tawfik Al-Hadhrami +2 位作者 Anjum Nazir Abdulsamad Ebrahim Yahya Atef Gharbi 《Computers, Materials & Continua》 SCIE EI 2024年第7期319-339,共21页
This paper contributes a sophisticated statistical method for the assessment of performance in routing protocols salient Mobile Ad Hoc Network(MANET)routing protocols:Destination Sequenced Distance Vector(DSDV),Ad hoc... This paper contributes a sophisticated statistical method for the assessment of performance in routing protocols salient Mobile Ad Hoc Network(MANET)routing protocols:Destination Sequenced Distance Vector(DSDV),Ad hoc On-Demand Distance Vector(AODV),Dynamic Source Routing(DSR),and Zone Routing Protocol(ZRP).In this paper,the evaluation will be carried out using complete sets of statistical tests such as Kruskal-Wallis,Mann-Whitney,and Friedman.It articulates a systematic evaluation of how the performance of the previous protocols varies with the number of nodes and the mobility patterns.The study is premised upon the Quality of Service(QoS)metrics of throughput,packet delivery ratio,and end-to-end delay to gain an adequate understanding of the operational efficiency of each protocol under different network scenarios.The findings explained significant differences in the performance of different routing protocols;as a result,decisions for the selection and optimization of routing protocols can be taken effectively according to different network requirements.This paper is a step forward in the general understanding of the routing dynamics of MANETs and contributes significantly to the strategic deployment of robust and efficient network infrastructures. 展开更多
关键词 routing protocols statistical approach friedman MANET
下载PDF
Dynamic Routing of Multiple QoS-Required Flows in Cloud-Edge Autonomous Multi-Domain Data Center Networks
11
作者 Shiyan Zhang Ruohan Xu +3 位作者 Zhangbo Xu Cenhua Yu Yuyang Jiang Yuting Zhao 《Computers, Materials & Continua》 SCIE EI 2024年第2期2287-2308,共22页
The 6th generation mobile networks(6G)network is a kind of multi-network interconnection and multi-scenario coexistence network,where multiple network domains break the original fixed boundaries to form connections an... The 6th generation mobile networks(6G)network is a kind of multi-network interconnection and multi-scenario coexistence network,where multiple network domains break the original fixed boundaries to form connections and convergence.In this paper,with the optimization objective of maximizing network utility while ensuring flows performance-centric weighted fairness,this paper designs a reinforcement learning-based cloud-edge autonomous multi-domain data center network architecture that achieves single-domain autonomy and multi-domain collaboration.Due to the conflict between the utility of different flows,the bandwidth fairness allocation problem for various types of flows is formulated by considering different defined reward functions.Regarding the tradeoff between fairness and utility,this paper deals with the corresponding reward functions for the cases where the flows undergo abrupt changes and smooth changes in the flows.In addition,to accommodate the Quality of Service(QoS)requirements for multiple types of flows,this paper proposes a multi-domain autonomous routing algorithm called LSTM+MADDPG.Introducing a Long Short-Term Memory(LSTM)layer in the actor and critic networks,more information about temporal continuity is added,further enhancing the adaptive ability changes in the dynamic network environment.The LSTM+MADDPG algorithm is compared with the latest reinforcement learning algorithm by conducting experiments on real network topology and traffic traces,and the experimental results show that LSTM+MADDPG improves the delay convergence speed by 14.6%and delays the start moment of packet loss by 18.2%compared with other algorithms. 展开更多
关键词 MULTI-DOMAIN data center networks AUTONOMOUS routING
下载PDF
Frequency-tunable single-photon router based on a microresonator containing a driven three-level emitter
12
作者 黄劲松 胡菁兰 +1 位作者 李艳玲 徐中辉 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第6期377-381,共5页
We propose a frequency-tunable router of single photons with high routing efficiency, which is constructed by two waveguides mediately linked by a single-mode whispering gallery resonator with a driven three-level emi... We propose a frequency-tunable router of single photons with high routing efficiency, which is constructed by two waveguides mediately linked by a single-mode whispering gallery resonator with a driven three-level emitter. Quantum routing probability in the output port is obtained via the real-space Hamiltonian. By adjusting the resonator–emitter coupling and the drive, the desired continuous central frequencies for the resonance peaks of routing photons can be manipulated nearly linearly, with the assistance of Rabi splitting effect and optical Stark shift. The proposed routing system may provide potential applications in designing other frequency-modulation quantum optical devices, such as multiplexers,filters, and so on. 展开更多
关键词 quantum routing scattering theory optical waveguide MICRORESONATOR
下载PDF
Design Strategies of Expressway Routes and Interchanges
13
作者 Xiaomin Wu 《Journal of World Architecture》 2023年第3期53-58,共6页
Road traffic conditions can have an important impact on the economic development of various regions.Under the background of rapid social and economic development,more and more expressway construction projects are init... Road traffic conditions can have an important impact on the economic development of various regions.Under the background of rapid social and economic development,more and more expressway construction projects are initiated in various regions,including both new expressways and expansion of old expressways,and interchange design plays an important role.Scientific and reasonable interchange design can not only realize energy saving and low carbon footprint,but also be people-oriented and promote regional economic development.Therefore,this paper mainly analyzes the highway route and its interchange design strategy for reference. 展开更多
关键词 EXPRESSWAY routE Interchange design strategy
下载PDF
An Energy-Efficient Routing Algorithm for UAV Formation Based on Time-Aggregated Graph
14
作者 Wang Gaifang Li Bo +1 位作者 Yang Hongjuan Jiang Xu 《China Communications》 SCIE CSCD 2024年第11期28-39,共12页
The limited energy and high mobility of unmanned aerial vehicles(UAVs)lead to drastic topology changes in UAV formation.The existing routing protocols necessitate a large number of messages for route discovery and mai... The limited energy and high mobility of unmanned aerial vehicles(UAVs)lead to drastic topology changes in UAV formation.The existing routing protocols necessitate a large number of messages for route discovery and maintenance,greatly increasing network delay and control overhead.A energyefficient routing method based on the discrete timeaggregated graph(TAG)theory is proposed since UAV formation is a defined time-varying network.The network is characterized using the TAG,which utilizes the prior knowledge in UAV formation.An energyefficient routing algorithm is designed based on TAG,considering the link delay,relative mobility,and residual energy of UAVs.The routing path is determined with global network information before requesting communication.Simulation results demonstrate that the routing method can improve the end-to-end delay,packet delivery ratio,routing control overhead,and residual energy.Consequently,introducing timevarying graphs to design routing algorithms is more effective for UAV formation. 展开更多
关键词 energy-efficient route time-aggregated graph UAV formation
下载PDF
QoS Routing Optimization Based on Deep Reinforcement Learning in SDN
15
作者 Yu Song Xusheng Qian +2 位作者 Nan Zhang Wei Wang Ao Xiong 《Computers, Materials & Continua》 SCIE EI 2024年第5期3007-3021,共15页
To enhance the efficiency and expediency of issuing e-licenses within the power sector, we must confront thechallenge of managing the surging demand for data traffic. Within this realm, the network imposes stringentQu... To enhance the efficiency and expediency of issuing e-licenses within the power sector, we must confront thechallenge of managing the surging demand for data traffic. Within this realm, the network imposes stringentQuality of Service (QoS) requirements, revealing the inadequacies of traditional routing allocation mechanismsin accommodating such extensive data flows. In response to the imperative of handling a substantial influx of datarequests promptly and alleviating the constraints of existing technologies and network congestion, we present anarchitecture forQoS routing optimizationwith in SoftwareDefinedNetwork (SDN), leveraging deep reinforcementlearning. This innovative approach entails the separation of SDN control and transmission functionalities, centralizingcontrol over data forwardingwhile integrating deep reinforcement learning for informed routing decisions. Byfactoring in considerations such as delay, bandwidth, jitter rate, and packet loss rate, we design a reward function toguide theDeepDeterministic PolicyGradient (DDPG) algorithmin learning the optimal routing strategy to furnishsuperior QoS provision. In our empirical investigations, we juxtapose the performance of Deep ReinforcementLearning (DRL) against that of Shortest Path (SP) algorithms in terms of data packet transmission delay. Theexperimental simulation results show that our proposed algorithm has significant efficacy in reducing networkdelay and improving the overall transmission efficiency, which is superior to the traditional methods. 展开更多
关键词 Deep reinforcement learning SDN route optimization QOS
下载PDF
An SDN-Based Algorithm for Caching,Routing,and Load Balancing in ICN
16
作者 MohammadBagher Tavasoli Hossein Saidi Ali Ghiasian 《China Communications》 SCIE CSCD 2024年第5期64-76,共13页
One of the challenges of Informationcentric Networking(ICN)is finding the optimal location for caching content and processing users’requests.In this paper,we address this challenge by leveraging Software-defined Netw... One of the challenges of Informationcentric Networking(ICN)is finding the optimal location for caching content and processing users’requests.In this paper,we address this challenge by leveraging Software-defined Networking(SDN)for efficient ICN management.To achieve this,we formulate the problem as a mixed-integer nonlinear programming(MINLP)model,incorporating caching,routing,and load balancing decisions.We explore two distinct scenarios to tackle the problem.Firstly,we solve the problem in an offline mode using the GAMS environment,assuming a stable network state to demonstrate the superior performance of the cacheenabled network compared to non-cache networks.Subsequently,we investigate the problem in an online mode where the network state dynamically changes over time.Given the computational complexity associated with MINLP,we propose the software-defined caching,routing,and load balancing(SDCRL)algorithm as an efficient and scalable solution.Our evaluation demonstrates that the SDCRL algorithm significantly reduces computational time while maintaining results that closely resemble those achieved by GAMS. 展开更多
关键词 in-network caching information-centric network power efficiency routING software-defined networking
下载PDF
Improving Network Availability through Optimized Multipath Routing and Incremental Deployment Strategies
17
作者 Wei Zhang Haijun Geng 《Computers, Materials & Continua》 SCIE EI 2024年第7期427-448,共22页
Currently,distributed routing protocols are constrained by offering a single path between any pair of nodes,thereby limiting the potential throughput and overall network performance.This approach not only restricts th... Currently,distributed routing protocols are constrained by offering a single path between any pair of nodes,thereby limiting the potential throughput and overall network performance.This approach not only restricts the flow of data but also makes the network susceptible to failures in case the primary path is disrupted.In contrast,routing protocols that leverage multiple paths within the network offer a more resilient and efficient solution.Multipath routing,as a fundamental concept,surpasses the limitations of traditional shortest path first protocols.It not only redirects traffic to unused resources,effectively mitigating network congestion,but also ensures load balancing across the network.This optimization significantly improves network utilization and boosts the overall performance,making it a widely recognized efficient method for enhancing network reliability.To further strengthen network resilience against failures,we introduce a routing scheme known as Multiple Nodes with at least Two Choices(MNTC).This innovative approach aims to significantly enhance network availability by providing each node with at least two routing choices.By doing so,it not only reduces the dependency on a single path but also creates redundant paths that can be utilized in case of failures,thereby enhancing the overall resilience of the network.To ensure the optimal placement of nodes,we propose three incremental deployment algorithms.These algorithms carefully select the most suitable set of nodes for deployment,taking into account various factors such as node connectivity,traffic patterns,and network topology.By deployingMNTCon a carefully chosen set of nodes,we can significantly enhance network reliability without the need for a complete overhaul of the existing infrastructure.We have conducted extensive evaluations of MNTC in diverse topological spaces,demonstrating its effectiveness in maintaining high network availability with minimal path stretch.The results are impressive,showing that even when implemented on just 60%of nodes,our incremental deployment method significantly boosts network availability.This underscores the potential of MNTC in enhancing network resilience and performance,making it a viable solution for modern networks facing increasing demands and complexities.The algorithms OSPF,TBFH,DC and LFC perform fast rerouting based on strict conditions,while MNTC is not restricted by these conditions.In five real network topologies,the average network availability ofMNTCis improved by 14.68%,6.28%,4.76%and 2.84%,respectively,compared with OSPF,TBFH,DC and LFC. 展开更多
关键词 Multipath routing network availability incremental deployment schemes genetic algorithm
下载PDF
Towards Blockchain-Based Secure BGP Routing,Challenges and Future Research Directions
18
作者 Qiong Yang Li Ma +3 位作者 Shanshan Tu Sami Ullah MuhammadWaqas Hisham Alasmary 《Computers, Materials & Continua》 SCIE EI 2024年第5期2035-2062,共28页
Border Gateway Protocol(BGP)is a standard inter-domain routing protocol for the Internet that conveys network layer reachability information and establishes routes to different destinations.The BGP protocol exhibits s... Border Gateway Protocol(BGP)is a standard inter-domain routing protocol for the Internet that conveys network layer reachability information and establishes routes to different destinations.The BGP protocol exhibits security design defects,such as an unconditional trust mechanism and the default acceptance of BGP route announcements from peers by BGP neighboring nodes,easily triggering prefix hijacking,path forgery,route leakage,and other BGP security threats.Meanwhile,the traditional BGP security mechanism,relying on a public key infrastructure,faces issues like a single point of failure and a single point of trust.The decentralization,anti-tampering,and traceability advantages of blockchain offer new solution ideas for constructing secure and trusted inter-domain routing mechanisms.In this paper,we summarize the characteristics of BGP protocol in detail,sort out the BGP security threats and their causes.Additionally,we analyze the shortcomings of the traditional BGP security mechanism and comprehensively evaluate existing blockchain-based solutions to address the above problems and validate the reliability and effectiveness of blockchain-based BGP security methods in mitigating BGP security threats.Finally,we discuss the challenges posed by BGP security problems and outline prospects for future research. 展开更多
关键词 BGP security blockchain prefix hijacking trust model secure routing
下载PDF
Mitigating Blackhole and Greyhole Routing Attacks in Vehicular Ad Hoc Networks Using Blockchain Based Smart Contracts
19
作者 Abdulatif Alabdulatif Mada Alharbi +1 位作者 Abir Mchergui Tarek Moulahi 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第2期2005-2021,共17页
The rapid increase in vehicle traffic volume in modern societies has raised the need to develop innovative solutions to reduce traffic congestion and enhance traffic management efficiency.Revolutionary advanced techno... The rapid increase in vehicle traffic volume in modern societies has raised the need to develop innovative solutions to reduce traffic congestion and enhance traffic management efficiency.Revolutionary advanced technology,such as Intelligent Transportation Systems(ITS),enables improved traffic management,helps eliminate congestion,and supports a safer environment.ITS provides real-time information on vehicle traffic and transportation systems that can improve decision-making for road users.However,ITS suffers from routing issues at the network layer when utilising Vehicular Ad Hoc Networks(VANETs).This is because each vehicle plays the role of a router in this network,which leads to a complex vehicle communication network,causing issues such as repeated link breakages between vehicles resulting from the mobility of the network and rapid topological variation.This may lead to loss or delay in packet transmissions;this weakness can be exploited in routing attacks,such as black-hole and gray-hole attacks,that threaten the availability of ITS services.In this paper,a Blockchain-based smart contracts model is proposed to offer convenient and comprehensive security mechanisms,enhancing the trustworthiness between vehicles.Self-Classification Blockchain-Based Contracts(SCBC)and Voting-Classification Blockchain-Based Contracts(VCBC)are utilised in the proposed protocol.The results show that VCBC succeeds in attaining better results in PDR and TP performance even in the presence of Blackhole and Grayhole attacks. 展开更多
关键词 Blockchain data privacy machine learning routing attacks smart contract VANET
下载PDF
Trust-based co-operative routing for secure communication in mobile ad hoc networks
20
作者 Ankita A.Mahamune M.M.Chandane 《Digital Communications and Networks》 SCIE CSCD 2024年第4期1079-1087,共9页
The working of a Mobile Ad hoc NETwork(MANET)relies on the supportive cooperation among the network nodes.But due to its intrinsic features,a misbehaving node can easily lead to a routing disorder.This paper presents ... The working of a Mobile Ad hoc NETwork(MANET)relies on the supportive cooperation among the network nodes.But due to its intrinsic features,a misbehaving node can easily lead to a routing disorder.This paper presents two trust-based routing schemes,namely Trust-based Self-Detection Routing(TSDR)and Trust-based Cooperative Routing(TCOR)designed with an Ad hoc On-demand Distance Vector(AODV)protocol.The proposed work covers a wide range of security challenges,including malicious node identification and prevention,accurate trust quantification,secure trust data sharing,and trusted route maintenance.This brings a prominent solution for mitigating misbehaving nodes and establishing efficient communication in MANET.It is empirically validated based on a performance comparison with the current Evolutionary Self-Cooperative Trust(ESCT)scheme,Generalized Trust Model(GTM),and the conventional AODV protocol.The extensive simulations are conducted against three different varying network scenarios.The results affirm the improved values of eight popular performance metrics overcoming the existing routing schemes.Among the two proposed works,TCOR is more suitable for highly scalable networks;TSDR suits,however,the MANET application better with its small size.This work thus makes a significant contribution to the research community,in contrast to many previous works focusing solely on specific security aspects,and results in a trade-off in the expected values of evaluation parameters and asserts their efficiency. 展开更多
关键词 Mobile Ad hoc NETwork Secure communication AODV Co-operative routing Trust metric
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部