traffic engineering
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Geofluids ◽  
2022 ◽  
Vol 2022 ◽  
pp. 1-14
Author(s):  
Xiao Feng ◽  
Chong Xia ◽  
Sifeng Zhang ◽  
Chuangui Li ◽  
Hongkui Zhao ◽  
...  

In the treatment of goafs in traffic engineering, technical problems such as those related to large-volume grouting and the precise control of material properties are often encountered. To address these issues, we developed a new composite material comprising cement-fly ash-modified sodium silicate (C-FA-MS). The setting time, fluidity, unconfined compressive strength, and microstructure were varied for different proportions of cement-sodium silicate (C-S) slurry, cement-fly ash-sodium silicate (C-FA-S) slurry, and C-FA-MS slurry, and their performances were compared and analysed. The experimental results showed that the initial setting time of the slurry was the shortest when both the original sodium silicate volume ratio ( V S ) and modified sodium silicate volume ratio ( V MS ) were 0.2. The final setting time of the C-S and C-FA-S slurries tended to decrease but then increased with decrease in V S , while that of the C-FA-MS slurry increased with lower V MS . The fluidity of the C-FA-S and C-FA-MS slurries decreased with decrease in V S or V MS at different fly ash admixture ratios. The consolidation compressive strength of C-S increased with decreasing V S , while that of C-FA-S showed a considerable increase only when V S decreased from 0.4 to 0.2. Meanwhile, the compressive strength of the C-FA-MS concretions first increased and then decreased with decrease in V MS . Microstructural analysis revealed that there were more cracks in the C-S agglomerate, the fly ash in the C-FA-S agglomerate reduced the relative density of the skeletal structure, and the stronger cross-linking in the C-FA-MS agglomerate improved the strength of the agglomerate. Under the condition of unit grouting volume, the cost of the C-FA-MS slurry was approximately 44.7% and 31.3% lower than that of the C-S and C-FA-S slurries, respectively. The new C-FA-MS material was applied for the treatment of the goaf in the Wu Sizhuang coal mine. Core drilling detection and audiofrequency magnetotelluric survey revealed that the goaf was sufficiently filled.


Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 239
Author(s):  
Tongfa Deng ◽  
Jinwen Huang ◽  
Maosen Cao ◽  
Dayang Li ◽  
Mahmoud Bayat

Curved beam bridges, whose line type is flexible and beautiful, are an indispensable bridge type in modern traffic engineering. Nevertheless, compared with linear bridges, curved beam bridges have more complex internal forces and deformation due to the curvature; therefore, this type of bridge is more likely to suffer damage in strong earthquakes. The occurrence of damage reduces the safety of bridges, and can even cause casualties and property loss. For this reason, it is of great significance to study the identification of seismic damage in curved beam bridges. However, there is currently little research on curved beam bridges. For this reason, this paper proposes a damage identification method based on wavelet packet norm entropy (WPNE) under seismic excitation. In this method, wavelet packet transform is adopted to highlight the damage singularity information, the norm entropy of wavelet coefficient is taken as a damage characteristic factor, and then the occurrence of damage is characterized by changes in the damage index. To verify the feasibility and effectiveness of this method, a finite element model of Curved Continuous Rigid-Frame Bridges (CCRFB) is established for the purposes of numerical simulation. The results show that the damage index based on WPNE can accurately identify the damage location and characterize the severity of damage; moreover, WPNE is more capable of performing damage location and providing early warning than the method based on wavelet packet energy. In addition, noise resistance analysis shows that WPNE is immune to noise interference to a certain extent. As long as a series of frequency bands with larger correlation coefficients are selected for WPNE calculation, independent noise reduction can be achieved.


Author(s):  
Aymen Hasan Alawadi ◽  
Sándor Molnár

AbstractData center networks (DCNs) act as critical infrastructures for emerging technologies. In general, a DCN involves a multi-rooted tree with various shortest paths of equal length from end to end. The DCN fabric must be maintained and monitored to guarantee high availability and better QoS. Traditional traffic engineering (TE) methods frequently reroute large flows based on the shortest and least-congested paths to maintain high service availability. This procedure results in a weak link utilization with frequent packet reordering. Moreover, DCN link failures are typical problems. State-of-the-art approaches address such challenges by modifying the network components (switches or hosts) to discover and avoid broken connections. This study proposes Oddlab (Odds labels), a novel deployable TE method to guarantee the QoS of multi-rooted data center (DC) traffic in symmetric and asymmetric modes. Oddlab creatively builds a heuristic model for efficient flow scheduling and faulty link detection by exclusively using the gathered statistics from the DCN data plane, such as residual bandwidth and the number of installed elephant flows. Besides, the proposed method is implemented in an SDN-based DCN without altering the network components. Our findings indicate that Oddlab can minimize the flow completion time, maximize bisection bandwidth, improve network utilization, and recognize faulty links with sufficient accuracy to improve DC productivity.


2021 ◽  
Vol 13 (1) ◽  
pp. 32
Author(s):  
Hendra Bayu Susueno ◽  
Imam Tri Wibowo ◽  
Siti Ummi Masruroh ◽  
Dewi Khairani ◽  
I’im Umamil Khoiri

In the digital era is , the internet becomes a necessity . the increasing number of internet usage by various parties encourages ISPs to improve their service quality . To overcome the problem the IETF has introduced a service Multiprotcol . MPLS-TE allows for schemes TE where the tip router of the label switched path (LSP) can calculate the many routes efficiently through the network to the router tip of the tail of the LSP. TE consists of three steps principal that is the size , model, and control . MPLS-TE allows for schemes TE where the tip router of the label switched path (LSP) can calculate the many routes efficiently through the network to the router tip of the tail of the LSP. ISIS is one of the routing protocol that was created for the OSI mode, using the method of link state as a method of collecting the route , ISIS also will perform the collection of information and the status of all the links that exist in the network . Analysis of the IS-IS routing protocol with the Multiprotocol label switch Traffic Engineering based on the parameters of quality of service (QoS), namely throughput and packet loss where the simulation uses the GNS3 network emulator. The test results prove that the values of throughput and packet loss are not much different.


Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8446
Author(s):  
Tuan-Minh Pham ◽  
Thi-Minh Nguyen

The massive amount of data generated daily by various sensors equipped with connected autonomous vehicles (CAVs) can lead to a significant performance issue of data processing and transfer. Network Function Virtualization (NFV) is a promising approach to improving the performance of a CAV system. In an NFV framework, Virtual Network Function (VNF) instances can be placed in edge and cloud servers and connected together to enable a flexible CAV service with low latency. However, protecting a service function chain composed of several VNFs from a failure is challenging in an NFV-based CAV system (VCAV). We propose an integer linear programming (ILP) model and two approximation algorithms for resilient services to minimize the service disruption cost in a VCAV system when a failure occurs. The ILP model, referred to as TERO, allows us to obtain the optimal solution for traffic engineering, including the VNF placement and routing for resilient services with regard to dynamic routing. Our proposed algorithms based on heuristics (i.e., TERH) and reinforcement learning (i.e., TERA) provide an approximation solution for resilient services in a large-scale VCAV system. Evaluation results with real datasets and generated network topologies show that TERH and TERA can provide a solution close to the optimal result. It also suggests that TERA should be used in a highly dynamic VCAV system.


Author(s):  
R Fışkın ◽  
E Nasibov ◽  
M O Yardımcı

Most of the accidents are caused by human error at sea so, decision making process made by navigators should be more computerised and automated. The supported decision making can be a step forward to decrease the risk of collision. This paper, in this respect, aims to present a deterministic approach to support optimum collision avoidance trajectory. This approach involves a collision avoidance course alteration. A web-based application coded with "JavaScript" programming language on the "Processing" software platform which allows the own ship to change her course in a deterministic manner to avoid collision optimally has been introduced. Algorithm structure of the method has been formulated and organized according to the International Regulation for Preventing Collision at Sea (COLREGs). The experimental tests results have revealed that the system is practicable and feasible and considerably outperforms heuristic-based method. It is thought that the developed method can be applied in an intelligent avoidance system on board and provides contribution to ship collision avoidance process, automation of ship motion control and ship traffic engineering.


Author(s):  
Volodymyr Andrushchak ◽  
Mykola Beshley ◽  
Lyubomyr Dutko ◽  
Taras Maksymyuk ◽  
Taras Andrukhiv

2021 ◽  
Author(s):  
◽  
Duncan Cameron

<p>The provision of rural broadband infrastructure is a challenge for network operators across the globe, irrespective of their size. Wireless Internet Service Providers (WISPs) have shown that the small-scale deployment of wireless broadband infrastructure is a viable alternative to relying on cellular network providers for remote coverage. However, WISPs must often resort to using off-grid renewable energy sources such as solar energy for powering network sites, often resulting in undesirable, low-performance backhaul radios being used between sites out of concern for excessive energy consumption.  The challenges of managing performant wireless backhaul networks in respect to energy constraints at remote, off-grid sites informs the need for energy-proportional design. Backhaul radios typically used by WISPs are not energy-proportional, meaning they use a consistent amount of energy, irrespective of wireless link utilisation. Using data from a real WISP network, diurnal traffic patterns show that WISP networks could benefit from energy-proportional design, without having to sacrifice performance.  To encourage the development of high-performance, energy-proportional WISP backhaul networks, ElasticWISP, an optimisation architecture that reduces network-wide backhaul energy consumption while satisfying the user-demand for traffic, is introduced. ElasticWISP dynamically controls the configuration of backhaul radios based on bandwidth demands and the network-wide energy consumption of these radios. Through simulations driven by real WISP topology and data traffic, results show that ElasticWISP can offer energy savings of approximately 65% when WISP operators follow the proposed backhaul design methodology.  Finally, a lightweight Multiprotocol Label Switching (MPLS)-based traffic engineering scheme, based on Segment Routing, is proposed. The implementation, named Segment Routing over MPLS (SR-MPLS), keeps traffic engineering path-state within each packet, meaning per-flow state is only held at SR-MPLS ingress routers. The lightweight approach of SR-MPLS also eliminates the otherwise necessary network-wide label flooding of traditional Segment Routing, making it ideal for bandwidth-sensitive wireless backhaul networks. Evaluation of SR-MPLS shows that it can perform as well as – and sometimes better than – competitor schemes.</p>


2021 ◽  
Author(s):  
◽  
Duncan Cameron

<p>The provision of rural broadband infrastructure is a challenge for network operators across the globe, irrespective of their size. Wireless Internet Service Providers (WISPs) have shown that the small-scale deployment of wireless broadband infrastructure is a viable alternative to relying on cellular network providers for remote coverage. However, WISPs must often resort to using off-grid renewable energy sources such as solar energy for powering network sites, often resulting in undesirable, low-performance backhaul radios being used between sites out of concern for excessive energy consumption.  The challenges of managing performant wireless backhaul networks in respect to energy constraints at remote, off-grid sites informs the need for energy-proportional design. Backhaul radios typically used by WISPs are not energy-proportional, meaning they use a consistent amount of energy, irrespective of wireless link utilisation. Using data from a real WISP network, diurnal traffic patterns show that WISP networks could benefit from energy-proportional design, without having to sacrifice performance.  To encourage the development of high-performance, energy-proportional WISP backhaul networks, ElasticWISP, an optimisation architecture that reduces network-wide backhaul energy consumption while satisfying the user-demand for traffic, is introduced. ElasticWISP dynamically controls the configuration of backhaul radios based on bandwidth demands and the network-wide energy consumption of these radios. Through simulations driven by real WISP topology and data traffic, results show that ElasticWISP can offer energy savings of approximately 65% when WISP operators follow the proposed backhaul design methodology.  Finally, a lightweight Multiprotocol Label Switching (MPLS)-based traffic engineering scheme, based on Segment Routing, is proposed. The implementation, named Segment Routing over MPLS (SR-MPLS), keeps traffic engineering path-state within each packet, meaning per-flow state is only held at SR-MPLS ingress routers. The lightweight approach of SR-MPLS also eliminates the otherwise necessary network-wide label flooding of traditional Segment Routing, making it ideal for bandwidth-sensitive wireless backhaul networks. Evaluation of SR-MPLS shows that it can perform as well as – and sometimes better than – competitor schemes.</p>


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