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Zhang, Pengtao, Peng Bai, Chaoqi Fu i Shanshan Li. "Dynamic Repair and Robust Optimization of Complex Networks". Mathematical Problems in Engineering 2020 (31.05.2020): 1–7. http://dx.doi.org/10.1155/2020/4131502.
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Network repair is indispensable for maintaining network security. Conventional static repair is relatively inefficient. In this study, by considering the energy transfer between nodes, a dynamic repair model was established. The fundamental reason for the secondary failure of repaired nodes during the dynamic repair process is the coupling structure of failure networks. A dynamic repair strategy was proposed that can effectively prevent the secondary failure of repair nodes influenced by energy during repair and can cause the redundant capacity of repair nodes to be used reasonably. By turning off the energy transfer function of the link to control the excessive flow of energy into the repair node to avoid the occurrence of secondary failure; on the other hand, by sharing part of the load of the failure node, realize the rational use of the redundant capacity of the repair node to reduce the impact of the failure node on the overall function of the network. The proposed strategy mitigated the effect of failure nodes on network functions and substantially improved the recovery efficiency of network functions. Furthermore, redundant edges, behaving as energy redundant links in a network structure, can considerably improve the robustness of the network by optimizing the removal of redundant edges. Dynamic repair is not only an efficient repair method but also a highly flexible choice for network repair.
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Ye, Miao, Qinghao Zhang, Ruoyu Wei, Yong Wang i Xiaofang Deng. "A New Method for Reconstructing Data Considering the Factor of Selected Provider Nodes Set in Distributed Storage System". Mathematics 10, nr 10 (19.05.2022): 1739. http://dx.doi.org/10.3390/math10101739.
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In the distributed storage system, when data need to be recovered after node failure, the erasure code redundancy method occupies less storage space than the multi-copy method. At present, the repair mechanism using erasure code to reconstruct the failed node only considers the improvement of link bandwidth on the repair rate and does not consider the impact of the selection of data providing node-set on the repair performance. A single node fault data reconstruction method based on the Software Defined Network (SDN) using the erasure code method is designed to solve the above problems. This method collects the network link-state through SDN, establishes a multi-attribute decision-making model of the data providing node-set based on the node performance, and determines the data providing nodes participating in providing data through the ideal point method. Then, the data recovery problem of a single fault node is modeled as the optimization problem of an optimal repair tree, and a hybrid genetic algorithm is designed to solve it. The experimental results show that under the same erasure code scale, after selecting the nodes of the data providing node-set, compared with the traditional tree topology and star topology, the repair delay distribution of the designed single fault node repair method for a distributed storage system is reduced by 15% and 45% respectively, and the repair flow is close to the star topology, which is reduced by 40% compared with the traditional tree repair.
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Xu, Bao, i Yong Feng Ju. "Distributed Coverage-Hole Repair Algorithm towards Nodes Failure in Wireless Sensor Networks". Applied Mechanics and Materials 135-136 (październik 2011): 464–69. http://dx.doi.org/10.4028/www.scientific.net/amm.135-136.464.
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In order to preserve the coverage and ensure the efficiency of Wireless Sensor Networks (WSNs), a distributed coverage-hole repair algorithm towards nodes failure is proposed in this paper. Every node has a energy threshold, if node’s energy is lower than its threshold, it sends a failure message to the nearest node and appoints it as the head node, the head node consideres all the neighbors of the failure node are preparatory boundary nodes at first, then judges every preparatory boundary nodes whether be a non-boundary node through the intersection angle with the failure node. In the last, the head node activates the redundant node within the sensing range of failure node which has the most boundary nodes as neighbor nodes. Analyzes and simulation on Matlab platform indicate that this algorithm has a low time complexity and the repair efficiency has a grate relation with node density and node sensing radius.
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Ye, Miao, Ruoyu Wei, Wei Guo, Qiuxiang Jiang, Hongbing Qiu i Yong Wang. "A New Method for Reconstructing Data on a Single Failure Node in the Distributed Storage System Based on the MSR Code". Wireless Communications and Mobile Computing 2021 (31.03.2021): 1–14. http://dx.doi.org/10.1155/2021/5574255.
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As a storage method for a distributed storage system, an erasure code can save storage space and repair the data of failed nodes. However, most studies that discuss the repair of fault nodes in the erasure code mode only focus on the condition that the bandwidth of heterogeneous links restricts the repair rate but ignore the condition that the storage node is heterogeneous, the cost of repair traffic in the repair process, and the influence of the failure of secondary nodes on the repair process. An optimal repair strategy based on the minimum storage regenerative (MSR) code and a hybrid genetic algorithm is proposed for single-node fault scenarios to solve the above problems. In this work, the single-node data repair problem is modeled as an optimization problem of an optimal Steiner tree with constraints considering heterogeneous link bandwidth and heterogeneous node processing capacity and takes repair traffic and repair delay as optimization objectives. After that, a hybrid genetic algorithm is designed to solve the problem. The experimental results show that under the same scales used in the MSR code cases, our approach has good robustness and its repair delay decreases by 10% and 55% compared with the conventional tree repair topology and star repair topology, respectively; the repair flow increases by 10% compared with the star topology, and the flow rate of the conventional tree repair topology decreases by 40%.
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Chen, Ningjiang, Weitao Liu, Wenjuan Pu, Yifei Liu i Qingwei Zhong. "SDNC-Repair: A Cooperative Data Repair Strategy Based on Erasure Code for Software-Defined Storage". Sensors 23, nr 13 (22.06.2023): 5809. http://dx.doi.org/10.3390/s23135809.
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Erasure-code-based storage systems suffer from problems such as long repair time and low I/O performance, resulting in high repair costs. For many years, researchers have focused on reducing the cost of repairing erasure-code-based storage systems. In this study, we discuss the demerits of node selecting, data transferring and data repair in erasure-code-based storage systems. Based on the network topology and node structure, we propose SDNC-Repair, a cooperative data repair strategy based on erasure code for SDS (Software Defined Storage), and describe its framework. Then, we propose a data source selection algorithm that senses the available network bandwidth between nodes and a data flow scheduling algorithm in SDNC-Repair. Additionally, we propose a data repair method based on node collaboration and data aggregation. Experiments illustrate that the proposed method has better repair performance under different data granularities. Compared to the conventional repair method, although the SDNC-Repair is more constrained by the cross-rack bandwidth, it improves system throughput effectively and significantly reduces data repair time in scenarios where multiple nodes fail and bandwidth is limited.
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Platt, James Robert, Christopher Williams, Nicholas West, Jenny F. Seligmann i Damian JM Tolan. "Exploring the radiological differences of lymph nodes between mismatch repair deficient and mismatch repair proficient colon cancer." Journal of Clinical Oncology 41, nr 16_suppl (1.06.2023): e15643-e15643. http://dx.doi.org/10.1200/jco.2023.41.16_suppl.e15643.
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e15643 Background: Mismatch repair (MMR) deficient (dMMR) colon cancer (CC) accounts for 15-20% of CC diagnoses and is characterised by clinicopathological features distinct from MMR proficient (pMMR) CC. Regardless of MMR status, CT staging is a critical part of the workup for newly diagnosed CC. Whilst CT can accurately predict T stage, it is less effective for N stage. Incorrect N staging may risk poor prognostication, more invasive surgery and may have implications for emerging neoadjuvant therapies. We recently illustrated the impact of MMR status on CT staging, with N staging accuracy significantly worse in dMMR than pMMR CC. Furthermore, we highlighted the clinical utility of using serum inflammatory markers to predict N stage more accurately in dMMR CC. It is increasingly apparent that MMR status has implications for CT staging and should be considered when developing strategies to improve performance. It is therefore crucial to understand how lymph node appearances differ according to MMR status. Here, we investigated whether radiological features of lymph nodes differ between dMMR and pMMR CC. Methods: CT scans were retrospectively assessed for patients who underwent curative resection from March 2019 to July 2020. Axial images were used to identify nodes > 5mm in longest diameter within the tumour drainage territory. The following were collected for each node: location (pericolic, intermediate, main; according to Japanese Society for Cancer of the Colon and Rectum criteria), long axis diameter and short axis diameter. The following were collected for the largest node: short to long axis ratio (SLAr), attenuation and heterogeneity. Characteristics were compared between the dMMR and pMMR groups. Results: This cohort comprised 92 patients, with 53 and 39 in the pMMR and dMMR groups, respectively. As expected, there were greater proportions of females and right-sided tumours in the dMMR group. Median SLAr and median attenuation of the largest node were significantly greater in the dMMR than the pMMR group (0.7 v 0.57, p = 0.0012 and 53.1HU v 40.4HU, p = 0.013, respectively). Number and distribution of enlarged nodes, and location, long axis and heterogeneity of the largest node did not differ between the groups. Conclusions: dMMR and pMMR CC are increasingly recognised as distinct entities, with implications for prognosis and treatment. There is growing evidence illustrating the impact of MMR status on CT staging, and in particular N staging. Here, we illustrated the similarities and differences of lymph nodes on CT between dMMR and pMMR CC. To the best of our knowledge, this is the first analysis to explore the relevance of the largest node and to illustrate the SLAr and attenuation of the largest node being significantly greater in dMMR CC. Recognising these differences will be crucial as we develop strategies for selecting patients to receive neoadjuvant immunotherapy in dMMR CC.
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Liu, Shangdong, Donghui Liu, Yujian Feng i Yimu Ji. "Distributed Connectivity Restoration Algorithm with Optimal Repair Path in Wireless Sensor and Actor Networks". Journal of Sensors 2022 (19.04.2022): 1–16. http://dx.doi.org/10.1155/2022/9299564.
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The actor nodes in wireless sensor and actor network (WSAN) are responsible for receiving the perceived data, processing and collaborating with each other. In most scenarios, maintaining the connectivity of the interactor network is necessary to plan the optimal coordinated response. However, actors are vulnerable to damage due to their limited energy and harsh environment. At worst, such failure can split the interactor network, which is affecting network performance. To restore the network connectivity, the existing methods replace the failed node by selecting a redundant node in the network. Multiple nodes may be involved in moving from the redundant node to the failed node, thus forming a repair path. However, the repair paths generated by such methods are often not optimal. In this paper, we use the gradient generation and diffusion mechanism to restore the connectivity of the interactor network and propose a gradient-based distributed connectivity recovery (GDCR) algorithm. GDCR selects an optimal repair path from the global network based on the generated gradient distribution under fully distributed and localized conditions. GDCR can timely respond to the repair and minimize the recovery range and movement overhead. Simulation results verify the performance of the proposed algorithm.
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Wang, Zhangquan, Yourong Chen, Banteng Liu, Haibo Yang, Ziyi Su i Yunkai Zhu. "A sensor node scheduling algorithm for heterogeneous wireless sensor networks". International Journal of Distributed Sensor Networks 15, nr 1 (styczeń 2019): 155014771982631. http://dx.doi.org/10.1177/1550147719826311.
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To improve the regional coverage rate and network lifetime of heterogeneous wireless sensor networks, a sensor node scheduling algorithm for heterogeneous wireless sensor networks is proposed. In sensor node scheduling algorithm, heterogeneous perception radius of sensor node is considered. Incomplete coverage constraint and arc coverage interval are analyzed. Regional coverage increment optimization model, arc coverage increment optimization model, and residual energy optimization model are proposed. Multi-objective scheduling model is established using weight factors and integrated function. Furthermore, the heuristic method is proposed to solve the multi-objective optimization model, and scheduling scheme of heterogeneous sensor nodes is obtained. When the network is in operation for a period of time, some sensor nodes are invalid and relevant regions are uncovered. The repair method is proposed to wake up sleep sensor nodes and repair the coverage blind area. The simulation results show that if keeping the same regional coverage rate, sensor node scheduling algorithm improves network lifetime, increases number of living sensor nodes, and keeps average node energy consumption at a low level. Under certain conditions, sensor node scheduling algorithm outperforms DGREEDY, two-tiered scheduling, and minimum connected cover.
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Mittal, Swati, Anu Mehra, Nitin Rakesh i Rakesh Matam. "Optimizing Regeneration Time by Node Selection in Group Repair Code". International Journal of Mathematical, Engineering and Management Sciences 7, nr 2 (14.03.2022): 299–311. http://dx.doi.org/10.33889/ijmems.2022.7.2.020.
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Distributed storage systems use network coding techniques like replication, erasure codes, local codes, regeneration codes, hybrid code, double code and group repair code to store data efficiently and provide speedy recovery of data during failures. The performance of these approaches is mainly compared on the basis of storage required and repair bandwidth. Out of these, Group Repair Codes is the one that has optimal repair bandwidth for regeneration of nodes. Traditionally, the cost of regeneration was considered to be dependent on the number of nodes participating in the process and the amount of data being transferred. There was not much discussion on the heterogeneity of the network and the capacity of the links between the nodes. In real-time, the nodes are connected to each other with different link capacities due to which the same amount of data takes different duration in reaching its destination. Selecting the node with higher link capacity helps in reducing the data transfer time. So, considering the heterogeneous nature of the network, this paper reduces the regeneration time for Group Repair Codes (GRC). The node selection algorithms for data regeneration have been proposed for GRC and the results of simulation show significant improvement in the regeneration time. Further, the network coding in heterogeneous systems may be explored for factors like network traffic, intermediate nodes, data routing etc.
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Gou, Pingzhang, Miao Guo, Baoyong Guo i Shun Mao. "DHD-MEPO: A Novel Distributed Coverage Hole Detection and Repair Method for Three-Dimensional Hybrid Wireless Sensor Networks". Electronics 12, nr 11 (28.05.2023): 2445. http://dx.doi.org/10.3390/electronics12112445.
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A coverage hole is a problem that cannot be completely avoided in three-dimensional hybrid wireless sensor networks. It can lead to hindrances in monitoring tasks and adversely affect network performance. To address the problem of coverage holes caused by the uneven initial deployment of the network and node damage during operation, we propose a distributed hole detection and multi-objective optimization emperor penguin repair algorithm (DHD-MEPO). In the detection phase, the monitoring region is zoned as units according to the quantity of nodes and the sensing range, and static nodes use the sum-of-weights method to campaign for group nodes on their terms, determining the location of holes by calculating the coverage of each cell. In the repair phase, the set of repair nodes is determined by calculating the mobile node coverage redundancy. Based on the characteristics of complex environments, the regions of high hole levels are prioritized. Moreover, the residual energy homogeneity of nodes is considered for the design of multi-objective functions. A lens-imaging mapping learning strategy is introduced to perturb the location of repair nodes for the optimization of the emperor penguin algorithm. Experimental results illustrate that the DHD-MEPO, compared with the C-CICHH, 3D-VPCA, RA, EMSCOLER, and IERP algorithms, can balance the uniformity of the residual energy of each node while satisfying the network coverage requirements and network connectivity, which effectively improves the network coverage performance.
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Niu, Xin, i Jingjing Jiang. "Single node repair algorithm for a multimedia cloud storage system based on network coding". Journal of High Speed Networks 27, nr 3 (23.09.2021): 205–14. http://dx.doi.org/10.3233/jhs-210661.
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Multimedia is inconvenient to use, difficult to maintain, and redundant in data storage. In order to solve the above problems and apply cloud storage to the integration of university teaching resources, this paper designs a virtualized cloud storage platform for university multimedia classrooms. The platform has many advantages, such as reducing the initial investment in multimedia classrooms, simplifying management tasks, making maximum use of actual resources and easy access to resources. Experiments and analysis show the feasibility and effectiveness of the platform. Aiming at the problems of the single-node repair algorithm of the existing multimedia cloud storage system, the limited domain is large, the codec complexity is high, the disk I/O (Input/Output) cost is high, the storage overhead and the repair bandwidth are unbalanced, and a network coding-based approach is proposed. Multimedia cloud storage. System single node repair algorithm. The algorithm stores the grouped multimedia file data in groups in the system, and performs XOR (exclusive OR) on the data in the group on the GF(2) finite field. When some nodes fail, the new node only needs to be connected. Two to three non-faulty nodes in the same group can accurately repair the data in the failed node. Theoretical analysis and simulation results show that the algorithm can reduce the complexity and repair of the codec, and reduce the disk I/O overhead. In this case, the storage cost of the algorithm is consistent with the storage cost based on the minimum storage regeneration code algorithm, and the repair bandwidth cost is close to the minimum bandwidth regeneration code algorithm.
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Jubbori, Taher Ahmed. "On The Improving Of Routing Protocols In Ad-Hoc Network By Using Optimization Algorithms". Galoitica: Journal of Mathematical Structures and Applications 7, nr 1 (2023): 26–35. http://dx.doi.org/10.54216/gjmsa.070103.
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In this paper, a novel improved method is presented to perform the local repair process of AntHocNet protocol. In the novel proposed method, in the case of failed connection, the node that checks the connection looks for the link that leads to node which follows the out-of-service node instead of the destination node. If it is existed, then the path will be repaired and completed quickly.
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Zorgui, Marwen, i Zhiying Wang. "Centralized Multi-Node Repair Regenerating Codes". IEEE Transactions on Information Theory 65, nr 7 (lipiec 2019): 4180–206. http://dx.doi.org/10.1109/tit.2019.2898660.
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El-Taha, Muhammad, i Thomas Michaud. "An Efficient Convolution Algorithm for the Non-Markovian Two-Node Cyclic Network". Journal of Applied Mathematics 2021 (29.05.2021): 1–13. http://dx.doi.org/10.1155/2021/5550363.
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Consider a closed cyclic queueing model that consists of two nodes and a total of M customers. Each node buffer can accommodate all M customers. Node 1 has N ≤ M servers, each having an exponential service time with rate λ . The second node consists of a single server with a general service time distribution function B . . The well-known machine repair model with spares, where a set of identical machines, N , is served by a single repair person, is a key application of this model. This model has several other applications in performance evaluation, manufacturing, computer networks, and in reliability studies as it can be easily used to compute system availability. In this article, we give an efficient algorithm to derive an exact solution for the steady state system size probabilities. Our approach is based on developing an efficient polynomial convolution method to compute the transition probabilities of a birth process over node 2 service times and solving an imbedded Markov chain at node 2 service completion epochs. This is a significant improvement over the exponential algorithm given in an earlier paper. Numerical examples are given to demonstrate the performance of our method.
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Li, Qiangyi, i Ningzhong Liu. "Coverage Blind Area Repair Based on Perceived Multimedia Data Driven in Mobile Wireless Sensor Networks". Advances in Multimedia 2022 (12.04.2022): 1–10. http://dx.doi.org/10.1155/2022/2354024.
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Wireless sensor networks deploy a large number of wireless sensor nodes in the monitoring area to complete the target monitoring task. The coverage effect is an important index to evaluate wireless sensor networks. The effect of network coverage is realized by the wireless sensor nodes deployed in the monitoring area, because the reasonable deployment of sensor nodes can affect the accuracy, reliability, real time, and integrity of monitoring target data collection. The main purpose of network coverage is to use the least number of wireless sensor nodes to complete the monitoring task of targets in the monitoring area and to avoid the emergence of coverage blind areas. Random node deployment, electronic equipment failure, software error, fire spread, flood, and other phenomena may lead to large-scale failure of wireless sensor nodes. For the failure of some nodes, the phenomenon of coverage blind area appears in the network. In order to repair the coverage blind area in the network, a coverage blind area repair algorithm for wireless sensor networks is proposed in this article. The coverage blind area attracts the nodes, makes the nodes move, and repairs the coverage blind area in the network.
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Li, Xiaolu, Zuoru Yang, Jinhong Li, Runhui Li, Patrick P. C. Lee, Qun Huang i Yuchong Hu. "Repair Pipelining for Erasure-coded Storage: Algorithms and Evaluation". ACM Transactions on Storage 17, nr 2 (28.05.2021): 1–29. http://dx.doi.org/10.1145/3436890.
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We propose repair pipelining , a technique that speeds up the repair performance in general erasure-coded storage. By carefully scheduling the repair of failed data in small-size units across storage nodes in a pipelined manner, repair pipelining reduces the single-block repair time to approximately the same as the normal read time for a single block in homogeneous environments. We further design different extensions of repair pipelining algorithms for heterogeneous environments and multi-block repair operations. We implement a repair pipelining prototype, called ECPipe , and integrate it as a middleware system into two versions of Hadoop Distributed File System (HDFS) (namely, HDFS-RAID and HDFS-3) as well as Quantcast File System. Experiments on a local testbed and Amazon EC2 show that repair pipelining significantly improves the performance of degraded reads and full-node recovery over existing repair techniques.
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Zhang, Yijie, i Zhan Guo. "A Node Placement Optimization Algorithm in Heterogeneous WSN Based on Neighbor Nodes". Wireless Communications and Mobile Computing 2022 (22.08.2022): 1–20. http://dx.doi.org/10.1155/2022/6820076.
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Wireless sensor network (WSN) is an important part of the Internet of Things. With the application and development of the Internet of Things, the heterogeneity of WSN is put forward a higher demand. Node placement is a critical step in the heterogeneous wireless sensor network (HEWSN). It is very important to optimize the node placement to fundamentally prolong the lifetime, improve the performance, and decrease the cost of the HEWSN. In this paper, the node placement optimization problem of HEWSN with different sensing types’ nodes is studied. An improved algorithm named neighbor nodes directed evolved nondominated sorting genetic algorithm (NN-DENSGA) is proposed to solve the multiobjective optimization problem. Homogeneous neighbor nodes are considered to promote directional evolution, and heterogeneous neighbor nodes are considered to repair the coverage holes. In addition, a forced update strategy is designed to increase diversity of population. Experiments have shown that the proposed algorithm not only has improvements in optimization performance but also in convergence speed and stability.
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Zhu, Bing, i Hui Li. "Exploring Node Repair Locality in Fractional Repetition Codes". IEEE Communications Letters 20, nr 12 (grudzień 2016): 2350–53. http://dx.doi.org/10.1109/lcomm.2016.2605100.
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FERZLI, GEORGE S., HAKAN USAL, NAJI E. HAYEK, SCOTT ZEITLIN, JAMES B. HURWITZ i PETER ALBERT. "Hernia Repair During Endoscopic Extraperitoneal Lymph Node Dissection". Journal of Laparoendoscopic & Advanced Surgical Techniques 7, nr 3 (czerwiec 1997): 163–65. http://dx.doi.org/10.1089/lap.1997.7.163.
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Niu, Xin. "Optimizing DODAG Build with RPL Protocol". Mathematical Problems in Engineering 2021 (1.04.2021): 1–8. http://dx.doi.org/10.1155/2021/5579564.
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In the lossy wireless network routing system based on RPL technology, an improved DODAG construction optimization scheme is proposed for sensor nodes with low-power dissipation in the interference environment. If a node discovers that all paths between it and its neighbors have failed, the node reset action begins. Once the node reset is complete, the DODAG system build process is resumed. This prevents the DODAG root from initiating a global fix by incrementing the DODAG VersionNumer to produce a new version of the DODAG in a disruptive environment. The power loss caused by this global repair operation is avoided. The performance of DODAG in interference environment is enhanced, and the data retransmission rate is reduced.
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Liu, Xiaojie, i Ulrich Speidel. "RAODV Routing Protocol for Congestion Detection and Relief in Ad Hoc Wireless Networks". International Journal of Interdisciplinary Telecommunications and Networking 13, nr 4 (październik 2021): 21–34. http://dx.doi.org/10.4018/ijitn.2021100103.
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Ad hoc wireless networks depend on mutual collaboration among nodes. Congestion in ad hoc wireless networks thus presents more of a challenge than for other network types. This article proposes RAODV (relieving AODV), a modification of the AODV routing protocol, to handle congestion via third party neighbour nodes in dense and static ad hoc networks. RAODV nodes use a T-entropy threshold-based congestion detection algorithm to determine the congestion status of their neighbours. If RAODV determines that congestion is occurring, it then tries to relieve congestion via a local repair modification algorithm that replaces the congested node by a suitable monitoring/third party neighbour node. This article also shows evidence that RAODV results in better network performance than AODV in simulations with random network topologies.
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DAY, KHALED, i ABDEL-ELAH AL-AYYOUB. "ADAPTIVE FAULT-TOLERANT ROUTING IN STAR NETWORKS". Journal of Interconnection Networks 02, nr 02 (czerwiec 2001): 213–31. http://dx.doi.org/10.1142/s0219265901000336.
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We take advantage of the hierarchical structure of the star graph network to obtain an efficient method for constructing node-disjoint paths between arbitrary pairs of nodes in the network. A distributed fault-tolerant routing algorithm for the star network based on this construction method is then presented and evaluated. The proposed algorithm adapts the routing decisions in response to node failures. Node failure and repair conditions may arise dynamically (at any time) provided that the total number of faulty nodes at any given time is less than the node-connectivity n - 1 of the n-star. When a message is blocked due to faulty components, the source of the message is warned and requested to switch to a different node-disjoint path. The methods used to identify the paths, to propagate failure information back to source nodes, and to switch from a routing path to another incur little communication and computation overhead. We show that if the node failures occur 'reasonably' apart in time, then all messages will be routed on paths of length δ + ε where δ is the minimum distance between the source and the destination and ε is 0, 2, or 4. In the unlikely case where more failures occur in a 'short period', the algorithm still delivers all messages but via possibly longer paths.
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Park, Sang Hyun, Yoshua Esquenazi, David G. Kline i Daniel H. Kim. "Surgical outcomes of 156 spinal accessory nerve injuries caused by lymph node biopsy procedures". Journal of Neurosurgery: Spine 23, nr 4 (październik 2015): 518–25. http://dx.doi.org/10.3171/2014.12.spine14968.
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OBJECT Iatrogenic injuries to the spinal accessory nerve (SAN) are not uncommon during lymph node biopsy of the posterior cervical triangle (PCT). In this study, the authors review the operative techniques and surgical outcomes of 156 surgical repairs of the SAN following iatrogenic injury during lymph node biopsy procedures. METHODS This retrospective study examines the authors’ clinical and surgical experience with 156 patients with SAN injury between 1980 and 2012. All patients suffered iatrogenic SAN injuries during lymph node biopsy, with the vast majority (154/156, 98.7%) occurring in Zone I of the PCT. Surgery was performed on the basis of anatomical and electro-physiological findings at the time of the operation. The mean follow-up period was 24 months (range 8–44 months). RESULTS Of the 123 patients who underwent graft or suture repair, 107 patients (87%) improved to Grade 3 functionality or higher using the Louisiana State University Health Science Center (LSUHSC) grading system. Neurolysis was performed in 29 patients (19%) when the nerve was found in continuity with recordable nerve action potential (NAP) across the lesion. More than 95% of patients treated by neurolysis with positive NAP recordings recovered to LSUHSC Grade 3 or higher. Forty-one patients (26%) underwent end-to-end repair, while 82 patients (53%) underwent graft repair, and Grade 3 or higher recovery was assessed for 90% and 85% of these patients, respectively. The average graft length used was 3.81 cm. Neurotization was performed in 4 patients, 2 of whom recovered to Grade 2 and 3, respectively. CONCLUSIONS SAN injuries present challenges for surgical exploration and repair because of the nerve’s size and location in the PCT. However, through proper and timely intervention, patients with diminished or absent function achieved favorable functional outcomes. Surgeons performing lymph node biopsy procedures in Zone I of the PCT should be aware of the potential risk of injury to the SAN.
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Ding, Yuan Ming, Hao Qu i Xue Wang. "An Improved AODV Routing Protocol for High Moving VANET". Applied Mechanics and Materials 380-384 (sierpień 2013): 2286–91. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.2286.
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For the problems of the inefficient communication, increscent delay and raised packet loss rate etc. among the nodes caused by the frequent changes of topology in vehicular Ad hoc network (VANET), an improved solution of AODV (Ad hoc On-Demand Vector) routing protocol is proposed using the backup routing mechanism. By modifying the processing of nodes disposing route reply packet (RREP) packets, the source node maintains a routing to the destination node, at the same time it maintains a backup routing and modifies the local repair mechanism. The simulations analyze the performance of AODV routing protocol when the moving speeds of the nodes increase and the network structure changes frequently. The simulation results show that the packet delivery fraction (PDF) increases using the backup routing mechanism which improves the performance of AODV routing protocol.
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Chaaf, Amir, Mohammed Saleh Ali Muthanna, Ammar Muthanna, Soha Alhelaly, Ibrahim A. Elgendy, Abdullah M. Iliyasu i Ahmed A. Abd El-Latif. "Energy-Efficient Relay-Based Void Hole Prevention and Repair in Clustered Multi-AUV Underwater Wireless Sensor Network". Security and Communication Networks 2021 (30.06.2021): 1–20. http://dx.doi.org/10.1155/2021/9969605.
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Underwater wireless sensor networks (UWSNs) enable various oceanic applications which require effective packet transmission. In this case, sparse node distribution, imbalance in terms of overall energy consumption between the different sensor nodes, dynamic network topology, and inappropriate selection of relay nodes cause void holes. Addressing this problem, we present a relay-based void hole prevention and repair (ReVOHPR) protocol by multiple autonomous underwater vehicles (AUVs) for UWSN. ReVOHPR is a global solution that implements different phases of operations that act mutually in order to efficiently reduce and identify void holes and trap relay nodes to avoid it. ReVOHPR adopts the following operations as ocean depth (levels)-based equal cluster formation, dynamic sleep scheduling, virtual graph-based routing, and relay-assisted void hole repair. For energy-efficient cluster forming, entropy-based eligibility ranking (E2R) is presented, which elects stable cluster heads (CHs). Then, dynamic sleep scheduling is implemented by the dynamic kernel Kalman filter (DK2F) algorithm in which sleep and active modes are based on the node’s current status. Intercluster routing is performed by maximum matching nodes that are selected by dual criteria, and also the data are transmitted to AUV. Finally, void holes are detected and repaired by the bicriteria mayfly optimization (BiCMO) algorithm. The BiCMO focuses on reducing the number of holes and data packet loss and maximizes the quality of service (QoS) and energy efficiency of the network. This protocol is timely dealing with node failures in packet transmission via multihop routing. Simulation is implemented by the NS3 (AquaSim module) simulator that evaluates the performance in the network according to the following metrics: average energy consumption, delay, packet delivery rate, and throughput. The simulation results of the proposed REVOHPR protocol comparing to the previous protocols allowed to conclude that the REVOHPR has considerable advantages. Due to the development of a new protocol with a set of phases for data transmission, energy consumption minimization, and void hole avoidance and mitigation in UWSN, the number of active nodes rate increases with the improvement in overall QoS.
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Yang, BaoPing, i Kun Jiang. "Automatic Repair Method for D2D Communication Routing Buffer Overflow Vulnerability in Cellular Network". Scientific Programming 2021 (20.12.2021): 1–12. http://dx.doi.org/10.1155/2021/3963574.
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Repairing D2D communication routing buffer overflow in a cellular network is of great significance in improving communication quality and security. Due to the increase of user usage, the communication data are easy to exceed the boundary of the buffer, resulting in the reduction of covered data information. The traditional repair methods mainly repair through the characteristics of covered data information, ignoring the impact of network topology information transmission delay and packet loss during calculation, resulting in the problem of low communication security. A cellular network routing buffer overflow repair algorithm based on the homomorphic analysis of node residual energy is proposed; the cellular network D2D communication routing protocol is designed; the cellular network D2D communication protocol path index is determined; then, the cellular network D2D communication routing protocol is designed by analyzing node residual energy; and the cellular network D2D communication network routing optimization method based on AHP is designed. Big constructs the energy model of cellular network D2D communication network, solves and sets the routing optimization objective function, realizes the control of network routing, and repairs the buffer overflow. The experiment results show that the improved method can effectively reduce the packet loss rate of communication data, improve the anti-interference ability of the system, and ensure the security of network communication.
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Chen, Huey-Kuo, Huey-Wen Chou, Ping-Shan Ho i Hsuan Wang. "Real-Time Vehicle Routing for Repairing Damaged Infrastructures Due to Natural Disasters". Mathematical Problems in Engineering 2011 (2011): 1–25. http://dx.doi.org/10.1155/2011/874526.
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We address the task of repairing damaged infrastructures as a series of multidepot vehicle-routing problems with time windows in a time-rolling frame. The network size of the tackled problems changes from time to time, as new disaster nodes will be added to and serviced disaster nodes will be deleted from the current network. In addition, an inaccessible disaster node would become accessible when one of its adjacent disaster nodes has been repaired. By the “take-and-conquer” strategy, the repair sequence of the disaster nodes in the affected area can be suitably scheduled. Thirteen instances were tested with our proposed heuristic, that is, Chen et al.'s approach. For comparison, Hsueh et al.'s approach (2008) with necessary modification was also tested. The results show that Chen et al.'s approach performs slightly better for larger size networks in terms of objective value.
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Tkachenko, K. S. "Self-healing of cyberphysical systems based on the analysis of the results of analytical modeling". Philosophical Problems of IT & Cyberspace (PhilIT&C), nr 1 (2.08.2022): 4–17. http://dx.doi.org/10.17726/philit.2022.1.1.
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Cyberphysical systems may have the property of self-healing. To model self-healing processes in cyberphysical systems, it is worth considering the applicability of approaches to assessing the information characteristics of physical systems to complex computer systems. Therefore, it is possible to quantify the degree of degradation and the possibilities for self-healing of the studied cyberphysical computer system based on analytical modeling of the queuing system. Management of self-healing processes of a computer node of a cyberphysical system based on analytical modeling allows to reduce the operational costs of resources for the repair and maintenance of the node, increases the efficiency of the computer node, including by increasing the uptime in an efficient mode, that is, there are qualitative changes in the operation of the cyberphysical system. Self-healing of a cyberphysical system due to self-healing of computer nodes increases the level of its robustness and adaptability to external changes.
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Agarwal, V., T. B. Yuvaraja, S. S. Waigankar, P. Dev i A. Pednekar. "Post chemotherapy robotic retroperitoneal lymph node dissection with IVC repair". European Urology 79 (czerwiec 2021): S1774. http://dx.doi.org/10.1016/s0302-2838(21)01625-0.
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Kil, Yong Sung, Sang-Hyo Kim i Hosung Park. "MTTDL for Distributed Storage Systems with Dual Node Repair Capability". Journal of Korean Institute of Communications and Information Sciences 42, nr 2 (28.02.2017): 345–48. http://dx.doi.org/10.7840/kics.2017.42.2.345.
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Shum, Kenneth W., i Junyu Chen. "Cooperative repair of multiple node failures in distributed storage systems". International Journal of Information and Coding Theory 3, nr 4 (2016): 299. http://dx.doi.org/10.1504/ijicot.2016.079495.
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Pace Napoleone, Carlo, Elisabetta Mariucci, Emanuela Angeli, Guido Oppido i Gaetano D. Gargiulo. "Sinus node dysfunction after partial anomalous pulmonary venous connection repair". Journal of Thoracic and Cardiovascular Surgery 147, nr 5 (maj 2014): 1594–98. http://dx.doi.org/10.1016/j.jtcvs.2013.07.058.
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Xu, Ying, ZengRi Zeng i Ou Ding. "An energy efficient hole repair node scheduling algorithm for WSN". Wireless Networks 23, nr 1 (8.12.2015): 103–16. http://dx.doi.org/10.1007/s11276-015-1132-8.
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Kiba, D. A., A. S. Gudim, N. N. Liubushkina i S. G. Marushchenko. "Autonomous node in the short wave radio network". Radio industry (Russia) 29, nr 3 (21.08.2019): 26–32. http://dx.doi.org/10.21778/2413-9599-2019-29-3-26-32.
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The paper covers questions related to the creation of the comprehensive device designed for long-term autonomous operations as part of the radio networks for various purposes in short-wave bands. Such radio networks are intended for remote monitoring and control over facilities at distances of hundreds and thousands of kilometres. The device and features of functioning of autonomous nodes in short-wave radio networks are based on daily and seasonal characteristics of distribution of radio waves, operation under conditions of self-provision with electricity and in areas of harsh climate, as well as on impossibility of their timely repair and maintenance. The authors have proposed solutions to the issue of a reliable communication channel using advanced low-energy types of angle modulation with low-value signal-to-noise ratios and the choice of the best frequency for a given time of the day for specific nodes. There is an overview of issues related to the choice of an antenna type for the autonomous radio network node, taking into account changes of working ranges. The issue of power supply to the radio network node is solved by applying the combination of a photovoltaic panel and wind generator working from a frost-resistant battery. Thermal modes for electronic equipment are provided through the use of a thermostatically controlled container. Authors have presented a possible architecture for the short-wave range radio network node. The study results include advice for developers of autonomous nodes of shortwave radio networks.
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Noah, Andrew C., Thomas M. Li, Leandro M. Martinez, Susumu Wada, Jacob B. Swanson, Nathaniel P. Disser, Kristoffer B. Sugg, Scott A. Rodeo, Theresa T. Lu i Christopher L. Mendias. "Adaptive and innate immune cell responses in tendons and lymph nodes after tendon injury and repair". Journal of Applied Physiology 128, nr 3 (1.03.2020): 473–82. http://dx.doi.org/10.1152/japplphysiol.00682.2019.
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Tendon injuries are a common clinical condition with limited treatment options. The cellular components of the innate immune system, such as neutrophils and macrophages, have been studied in tendon injuries. However, the adaptive immune system, comprising specialized lymphocytes, plays an important role in orchestrating the healing of numerous tissues, but less is known about these cells in tendon healing. To gain a greater understanding of the biological processes that regulate tendon healing, we determined how the cellular components of the adaptive and innate immune system respond to a tendon injury using two-month-old male mice. We observed that lymphatic vasculature is present in the epitenon and superficial regions of Achilles tendons, and that the lymphatics drain into the popliteal lymph node. We then created an acute Achilles tenotomy followed by repair, and collected tendons and popliteal lymph nodes 1, 2, and 4 wk after injury. Tendon injury resulted in a robust adaptive immune cell response that followed an initial innate immune cell response in tendons and lymph nodes. Monocytes, neutrophils, and macrophages initially accumulated at 1 wk after injury in tendons, while dendritic cells and CD4+ T cells peaked at 2 wk after injury. B cells and CD8+ T cells progressively increased over time. In parallel, immune cells of the popliteal lymph node demonstrated a similarly coordinated response to the injury. These results suggest that there is an adaptive immune response to tendon injury, and adaptive immune cells may play a role in regulating tendon healing. NEW & NOTEWORTHY While the innate immune system, consisting of macrophages and related hematopoietic cells, has been studied in tendon injury, less is known about the adaptive immune system. Using a mouse model of Achilles tendon tenotomy and repair, we observed an adaptive immune cell response, consisting of CD4+ and CD8+ T cells, and B cells, which occur through 4 wk after tendon injury. This response appeared to be coordinated by the draining popliteal lymph node.
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Hu, Yuan. "Heap Adjustment Algorithms Based on Complete Binary Tree Structure". Applied Mechanics and Materials 321-324 (czerwiec 2013): 2122–27. http://dx.doi.org/10.4028/www.scientific.net/amm.321-324.2122.
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In many applications, it is necessary to adjust the node position of complete binary tree, making the data set have the nature of heap. Because when binary tree node data volume is huge, it will be needed apparently for heap adjustment efficiency of repair algorithms which is based on heap linear list to be improved. Now an improved algorithm is proposed by experiments, which utilizes characteristics of priority queue (delete the earliest data) and stack (delete the latest data), and conducts stack pushing on binary tree node, then accesses node successively to call glide adjustment algorithm to improve the adjustment efficiency.
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Zhuang, Li, Yaoguang Qi i Fenna Zhang. "Braking Control System of Oilfield Minor Repair Machine Based on Wireless Sensor Network". Security and Communication Networks 2021 (8.09.2021): 1–14. http://dx.doi.org/10.1155/2021/6966041.
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Traditional minor repair machines have low control efficiency and low automation. In order to improve the brake control efficiency of the oilfield minor repair machine, the oilfield minor repair machine brake control system based on wireless sensor network is designed. The front-end controller collects the data of the oilfield repair machine through the wireless sensor and realizes the communication between the sensor nodes and the data interaction with the communication node through the field bus inside the equipment. The server uploads the processed data through the 3G network, and the server receives the data from the front-end controller and saves it in the database. The remote-control center accesses the server through the Internet to view the front-end controller data. The brake control module uses the expert fuzzy PID control method to control the speed, oil pressure, and operating status of the oilfield minor repair machine and sends the data to the front-end control center to complete the oilfield minor repair remote-control machine by sending control instructions. Experimental results show that the system can meet the braking control requirements of oilfield minor repair machines, the output can quickly track input changes, the braking control effect is good, the dynamic deviation of the machine can be reduced, and the braking control efficiency can be improved.
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Arciuolo, Damiano, Antonio Travaglino, Angela Santoro, Giulia Scaglione, Nicoletta D’Alessandris, Michele Valente, Frediano Inzani i in. "L1CAM Expression in Microcystic, Elongated, and Fragmented (MELF) Glands Predicts Lymph Node Involvement in Endometrial Carcinoma". Cancers 14, nr 15 (26.07.2022): 3635. http://dx.doi.org/10.3390/cancers14153635.
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In endometrial carcinoma, both L1CAM overexpression and microcystic, elongated and fragmented (MELF) patterns of invasion have been related to epithelial-to-mesenchymal transition and metastatic spread. We aimed to assess the association between L1CAM expression, the MELF pattern, and lymph node status in endometrial carcinoma. Consecutive cases of endometrial carcinoma with MELF pattern were immunohistochemically assessed for L1CAM. Inclusion criteria were endometrioid-type, low-grade, stage T1, and known lymph node status. Uni- and multivariate logistic regression were used to assess the association of L1CAM expression with lymph node status. Fifty-eight cases were included. Most cases showed deep myometrial invasion (n = 42, 72.4%) and substantial lymphovascular space invasion (n = 34, 58.6%). All cases were p53-wild-type; 17 (29.3%) were mismatch repair-deficient. Twenty cases (34.5%) had positive nodes. No cases showed L1CAM positivity in ≥10% of the whole tumor. MELF glands expressed L1CAM at least focally in 38 cases (65.5%). L1CAM positivity in ≥10% of the MELF component was found in 24 cases (41.4%) and was the only significant predictor of lymph node involvement in both univariate (p < 0.001) and multivariate analysis (p < 0.001). In conclusion, L1CAM might be involved in the development of the MELF pattern. In uterine-confined, low-grade endometrioid carcinomas, L1CAM overexpression in MELF glands may predict lymph node involvement.
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Kruglik, Stanislav. "Minimum-storage regenerating codes resistant to special adversary". Information and Control Systems, nr 1 (3.03.2021): 38–44. http://dx.doi.org/10.31799/1684-8853-2021-1-38-44.
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Introduction: In order to deal with temporarily unavailable nodes in a distributed storage system, engineers apply special classes of erasure correction codes. These codes allow you to repair a temporarily unavailable node by downloading small amounts of data from the remaining ones. However, this creates safety threats in the presence of an eavesdropper. Purpose: Introducing a new mathematical model in which the eavesdropper has a limited access to all nodes in the system, and developing codes resistant to it. Methods: Information-theoretic arguments, and mixing information symbols with random ones by systematic Reed — Solomon code. Results: We introduced a new mathematical model of an eavesdropper with limited access to all nodes in a distributed storage system. Note that the proposed eavesdropper is passive, being unable to change the accessed data. We found parameters for optimal regenerating codes resistant to such adversary, and provided a technique to ensure necessary resistance. As a result, we obtained the construction of optimal minimum storage regenerating codes resistant to such adversary. Practical relevance: The proposed constructions can provide resistance to adversary while ensuring effective data repair.
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Kim, Daniel H., Yong-Jun Cho, Robert L. Tiel i David G. Kline. "Surgical Outcomes of 111 Spinal Accessory Nerve Injuries". Neurosurgery 53, nr 5 (1.11.2003): 1106–13. http://dx.doi.org/10.1227/01.neu.0000089058.82201.3d.
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Abstract OBJECTIVE Iatrogenic injury to the spinal accessory nerve is not uncommon during neck surgery involving the posterior cervical triangle, because its superficial course here makes it susceptible. We review injury mechanisms, operative techniques, and surgical outcomes of 111 surgical repairs of the spinal accessory nerve. METHODS This retrospective study examines clinical and surgical experience with spinal accessory nerve injuries at the Louisiana State University Health Sciences Center during a period of 23 years (1978–2000). Surgery was performed on the basis of anatomic and electrophysiological findings at the time of operation. Patients were followed up for an average of 25.6 months. RESULTS The most frequent injury mechanism was iatrogenic (103 patients, 93%), and 82 (80%) of these injuries involved lymph node biopsies. Eight injuries were caused by stretch (five patients) and laceration (three patients). The most common procedures were graft repairs in 58 patients. End-to-end repair was used in 26 patients and neurolysis in 19 patients if the nerve was found in continuity with intraoperative electrical evidence of regeneration. Five neurotizations, two burials into muscle, and one removal of ligature material were also performed. More than 95% of patients treated by neurolysis supported by positive nerve action potential recordings improved to Grade 4 or higher. Of 84 patients with lesions repaired by graft or suture, 65 patients (77%) recovered to Grade 3 or higher. The average graft length was 1.5 inches. CONCLUSION Surgical exploration and repair of spinal accessory nerve injuries is difficult. With perseverance, however, these patients with complete or severe deficits achieved favorable functional outcomes through operative exploration and repair.
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Zorgui, Marwen, i Zhiying Wang. "An Outer Bound for Linear Multi-Node Exact Repair Regenerating Codes". IEEE Communications Letters 24, nr 9 (wrzesień 2020): 1861–64. http://dx.doi.org/10.1109/lcomm.2020.2996622.
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Yavari, Ehsan, i Morteza Esmaeili. "Locally Repairable Codes: Joint Sequential–Parallel Repair for Multiple Node Failures". IEEE Transactions on Information Theory 66, nr 1 (styczeń 2020): 222–32. http://dx.doi.org/10.1109/tit.2019.2940975.
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Takahashi, Hiroaki, Yoshihiro Oshima, Masahiro Yoshida, Masahiro Yamaguchi, Kenji Okada i Yutaka Okita. "Sinus node dysfunction after repair of partial anomalous pulmonary venous connection". Journal of Thoracic and Cardiovascular Surgery 136, nr 2 (sierpień 2008): 329–34. http://dx.doi.org/10.1016/j.jtcvs.2007.12.039.
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Wu, Jiajia, Donghui Ma, Wei Wang i Zhao Han. "Research on Sensor Placement for Disaster Prevention in Water Distribution Networks for Important Users". Sustainability 12, nr 2 (19.01.2020): 723. http://dx.doi.org/10.3390/su12020723.
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Sensor placement for disaster prevention for important users in urban water distribution networks is essential for post-earthquake monitoring and repair. Herein, we proposed a sensor placement approach for disaster prevention monitoring for important users, to (a) improve the fault diagnosis ability of the water distribution network and to (b) guarantee the function of emergency services for key nodes after an earthquake. First, an evaluation system of node users’ disaster prevention impact factors was presented to evaluate the node influence degree from three aspects: post-earthquake leakage, emergency support and topology structure; and the weight values of node users’ disaster prevention impact factors were obtained. Second, a post-earthquake hydraulic analysis model based on the pressure-driven demand was used to calculate the water shortage ratio of nodes. Third, using the three-way clustering integration method, the results of four clustering techniques were integrated to divide the monitoring domain in the water distribution network based on sensitivity analysis. Finally, on basis of the sensitivity matrix, the division of the monitoring area and the impact factors of node users’ disaster prevention were combined to place sensors for post-earthquake disaster prevention in the water distribution network. Detailed computational experiments for a real urban water network in China were performed and compared with the results of other traditional techniques to evaluate the performance of the proposed approach. The results show that the approach is better than traditional methods. It not only considers the actual hydraulic information of the water distribution network, but also the important user nodes after an earthquake, and is of great significance for emergency command and rescue and disaster relief after an earthquake in the city.
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Zhang, Wenzhu, Leilei Jiang, Xi Song i Zhengyuan Shao. "Weight-Based PA-GPSR Protocol Improvement Method in VANET". Sensors 23, nr 13 (28.06.2023): 5991. http://dx.doi.org/10.3390/s23135991.
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Vehicle Ad-hoc network (VANET) can provide technical support and solutions for the construction of intelligent and efficient transportation systems, and the routing protocol directly affects the efficiency of VANET. The rapid movement of nodes and uneven density distribution affect the routing stability and data transmission efficiency in VANET. To improve the local optimality and routing loops of the path-aware greedy perimeter stateless routing protocol (PA-GPSR) in urban sparse networks, a weight-based path-aware greedy perimeter stateless routing protocol (W-PAGPSR) is proposed. The protocol is divided into two stages. Firstly, in the routing establishment stage, the node distance, reliable node density, cumulative communication duration, and node movement direction are integrated to indicate the communication reliability of the node, and the next hop node is selected using the weight greedy forwarding strategy to achieve reliable transmission of data packets. Secondly, in the routing maintenance stage, based on the data packet delivery angle and reliable node density, the next hop node is selected for forwarding using the weight perimeter forwarding strategy to achieve routing repair. The simulation results show that compared to the greedy peripheral stateless routing protocol (GPSR), for the maximum distance–minimum angle greedy peripheral stateless routing (MM-GPSR) and PA-GPSR protocols, the packet loss rate of the protocol is reduced by an average of 24.47%, 25.02%, and 14.12%, respectively; the average end-to-end delay is reduced by an average of 48.34%, 79.96%, and 21.45%, respectively; and the network throughput is increased by an average of 47.68%, 58.39%, and 20.33%, respectively. This protocol improves network throughput while reducing the average end-to-end delay and packet loss rate.
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Garcez, Thalles V., i Przemyslaw Szufel. "Multidimensional Risk Management for Underground Electricity Networks". Studies in Logic, Grammar and Rhetoric 37, nr 1 (8.08.2014): 51–69. http://dx.doi.org/10.2478/slgr-2014-0017.
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Abstract In the paper we consider an electricity provider company that makes decision on allocating resources on electric network maintenance. The investments decrease malfunction rate of network nodes. An accidental event (explosion, fire, etc.) or a malfunctioning on underground system can have various consequences and in different perspectives, such as deaths and injuries of pedestrians, fires in nearby locations, disturbances in the flow of vehicular traffic, loss to the company image, operating and financial losses, etc. For this reason it is necessary to apply an approach of the risk management that considers the multidimensional view of the consequences. Furthermore an analysis of decision making should consider network dependencies between the nodes of the electricity distribution system. In the paper we propose the use of the simulation to assess the network effects (such as the increase of the probability of other accidental event and the occurrence of blackouts of the dependent nodes) in the multidimensional risk assessment in electricity grid. The analyzed effects include node overloading due to malfunction of adjacent nodes and blackouts that take place where there is temporarily no path in the grid between the power plant and a node. The simulation results show that network effects have crucial role for decisions in the network maintenance – outcomes of decisions to repair a particular node in the network can have significant influence on performance of other nodes. However, those dependencies are non-linear. The effects of network connectivity (number of connections between nodes) on its multidimensional performance assessment depend heavily on the overloading effect level. The simulation results do not depend on network type structure (random or small world) – however simulation outcomes for random networks have shown higher variance compared to small-world networks.
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Liu, Zhihai, Yuxuan Wang, Qingliang Zeng, Yang Yang i Zhenrui Dai. "Research on Optimization Measures of Zigbee Network Connection in an Imitated Mine Fading Channel". Electronics 10, nr 2 (14.01.2021): 171. http://dx.doi.org/10.3390/electronics10020171.
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Based on the background of a mine, this study aimed to improve underground wireless communication. The study selected Zigbee technology from many wireless technologies as the basis, expounded the technical advantages and disadvantages, and addressed its disadvantages. First, the modulation technology of Zigbee was improved. This article selects and describes O-QPSK technology from three modulation technologies, thereby addressing the synchronization difficulties caused by inherent technical reasons, and proposes a modulation method based on feedforward timing. Moreover, excellent performance was achieved in the follow-up simulation experiment. For networking problems, a series of mechanisms are proposed to address several problems in large-scale networking: node offline, energy waste, signal delay, etc. This article proposes five main mechanisms and an improved protocol from two significant perspectives. The problem of node disconnection is divided into two parts. Considering the different status of edge nodes and important nodes in the network, three mechanisms are proposed for edge nodes for disconnection detection and self-repair, and two mechanisms are proposed for essential nodes. This can compensate for the loss caused by the disconnection of essential nodes at a specific time. For network energy waste, an Improved-LEACH protocol is proposed to alleviate the signal delay problem. The performance of the five mechanisms and one protocol was verified in a simulation test, and the performance was reasonable and in line with expectations.
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Dixit, Prashant, Anuradha Pillai i Rahul Rishi. "QoS Enabled Improved Location Aided Routing (QEILA)". Recent Patents on Engineering 13, nr 1 (8.02.2019): 28–38. http://dx.doi.org/10.2174/1872212112666180601090209.
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Background: Transmission of heavy and real-time data over wireless links with Quality of Service in Mobile ad-hoc network is a very challenging task. Bandwidth and battery backup parameters are checks for Quality of Service. To provide the Quality of Service in mobile ad-hoc network, the aliveness of a transmitting node has a great concern. Location-aided routing methods for mobile ad-hoc network have gained popularity because of network’s energy saving. Location-aided routing keeps a minimal number of participating nodes for path construction between source and destination, but they did not consider the health of participating nodes that constitute a path. Objective: The objective of this work is harness the location aided routing and builds a protocol which provides Quality of Service in terms of required battery life and available bandwidth. Method: In this work, various patented and non-patented location-based routing and Quality of Service methods for wireless network have been reviewed. The improved location aided routing protocol has been utilized and equipped with Quality of Service check while selecting the next forwarding node for path construction. A novel path preservation procedure is proposed which repair the broken link locally by utilizing candidate next node table. Results: The simulation reveals that the proposed protocol constructs a reliable path consist of trustworthy nodes in terms of battery life and available bandwidth. Conclusion: Proposed work can be utilized for transmitting heavy data traffic in Mobile Ad-hoc network with Quality of Service in real time situation.
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Wang, Lei, Yulong Li, Bo Pan, Qiuwei Wu, Jun Yin i Lijie Xu. "Network Coding for Efficient Video Multicast in Device-to-Device Communications". Sensors 20, nr 8 (16.04.2020): 2254. http://dx.doi.org/10.3390/s20082254.
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Device-to-Device (D2D) communication is one of the critical technologies for the fifth-generation network, which allows devices to communicate directly with each other while increasing transmission rate, but this communication is vulnerable to interference. When video transmission is carried out in an environment with interference, problems such as high packet loss rate, poor quality of the video, and blurred screen may exist. These problems can be effectively solved by redundant coding operations at the source node, but the extra coding operation imposes a heavy computational burden on the source node. In order to alleviate the computational overhead of the source node, reduce transmission delay, and guarantee transmission quality, this paper proposes an efficient video multicast transmission scheme based on Random Linear Network Coding (RLNC) in D2D networks. In the scheme, the receiving devices in the transmission participate in the process of generating repair packets that are used to remedy the loss of encoded packets during transmission. The source node multicasts the encoded video file. The receiving nodes re-encode the received data packets with RLNC and then send them to the network again. The nearby nodes can decode the original data through the encoded or re-encoded data packets. The performance of the proposed scheme is evaluated through both simulation and real experiments. The experimental results show that compared with the traditional RLNC scheme, this scheme could balance the computation overhead of the mobile devices and reduce the encoding and decoding delay by about 8%. When the packet loss rate is high, the proposed scheme can obtain better video quality than the traditional replication-based scheme.
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Zhang, Jiefei, Gang Ren i Jianhua Song. "Resilience-Based Restoration Sequence Optimization for Metro Networks: A Case Study in China". Journal of Advanced Transportation 2022 (14.03.2022): 1–22. http://dx.doi.org/10.1155/2022/8595356.
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Metro station restoration sequence optimization is crucial during post-disaster recovery. Taking both budget limitations and repair time uncertainty into account, this paper proposes a resilience-based optimization model for choosing an optimal restoration sequence scheme, maximizing the global average efficiency, under the condition that the network accessibility meets given resilience requirements. Evolutionary algorithm NSGA-II is applied to solve the model. A Case study in Nanjing and Zhengzhou gives insights into restoration sequence strategies for decision-makers. Results show that a ring network is more robust than a radial network under the same scale attack. Under limited budget, the optimal restoration sequence is closely related to the damaged stations’ location and repair time. Specifically, if damaged stations’ distribution is relatively centralized and transfer stations need more repair time, giving repair priority to transfer stations is not always the best strategy. If damaged stations’ distribution is relatively scattered and all stations’ repair time is the same, the station with a bigger node degree should be repaired earlier. However, this conclusion may be invalid if transfer stations repair time is far longer than others. Sensitivity analysis show that the total budget is more sensitive than one day’s budget in the entire restoration phase. However, in the emergency phase, increasing one day’s budget is more significant for shortening recovery time. The proposed model can contribute to effective and flexible decision-making for metro network restorations.