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Hybrid Wireless Sensors Deployment Scheme with Connectivity and coverage Maintaining in Wireless Sensor Networks

WIRELESS PERSONAL COMMUNICATIONS 2020年第3期112卷 1893-1917页

作者： Njoya, Arouna Ndam Ari, Ado Adamou Abba Nana Awa, Marah Titouna, Chafiq Labraoui, Nabila Effa, Joseph Yves Abdou, Wahabou Gueroui, Abdelhak Univ Versailles St Quentin En Yvelines Univ Paris Saclay LI PaRAD Lab 45 Ave Etats Unis F-78035 Versailles France Univ Ngaoundere LASE Lab Dept Comp Engn POB 455 Ngaoundere Cameroon Univ Maroua LaRI Lab POB 814 Maroua Cameroon Univ Paris 05 LIPARADE Lab 45 Rue St Peres F-75006 Paris France Univ Abou Bekr Belkaid Tlemcen STIC Lab POB 230 Tilimsen 13000 Algeria Univ Burgundy LE2I Lab UMR CNRS 6306 9 Ave Alain Savary F-21000 Dijon France

With the rapid growth of the internet of things (IoT), an impressive number of IoT's application based on wireless sensor networks (WSNs) has been deployed in various domain. Due to its wide ranged applications, WSNs that have the capability to monitor a given sensing field, became the most used platform of IoT. Therefore, coverage becomes one of the most important challenge of WSNs. The search for better positions to assign to the sensors in order to control each point of an area of interest and the collection of data from sensors are major concerns in WSNs. This work addresses these problems by providing a hybrid approach that ensures sensors deployment on a grid for targets coverage while taking into account connectivity. The proposed sequential hybrid approach is based on three algorithms. The first places the sensors so as to all targets are covered. The second removes redundancies from the placement algorithm to reduce the number of sensors deployed. The third one, based on the genetic algorithm, aims to generate a connected graph which provide a minimal path that links deployed sensors and sink. Simulations and a comparative study were carried out to prove the relevance of the proposed method.

关键词： target coverage Connectivity Approximation algorithms Wireless sensor networks

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MMQT: Maximizing the Monitoring Quality for targets Based on Probabilistic Sensing Model in Rechargeable Wireless Sensor Networks

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IEEE ACCESS 2020年 8卷 77073-77088页

作者： Liao, Wen-Hwa Dande, Bhargavi Chang, Chih-Yung Roy, Diptendu Sinha Chuzhou Univ Sch Econ & Management Chuzhou 239000 Peoples R China Tatung Univ Dept Informat Management Taipei 10452 Taiwan Tamkang Univ Dept Comp Sci & Informat Engn New Taipei 25137 Taiwan Natl Inst Technol Meghalaya Dept Comp Sci & Engn Shillong 793003 Meghalaya India

In wireless sensor networks (WSNs), target coverage is an important issue which aims at finding a set of sensors to monitor the targets for maximizing both the surveillance quality and network lifetime. However, most of them assumed that each sensor is battery powered and the Boolean Sensing Model (BSM) is applied. Sensors powered by battery have a limited lifetime while the BSM is difficult to reflect the physical features of sensing. This paper proposes target coverage mechanisms, called C-MMQT and D-MMQT, which consider the solar-powered sensors and allows the battery to be recharged for maintaining the perpetual lifetime of sensor networks. The proposed mechanisms apply the Probabilistic Sensing Model (PSM) and consider that different targets have different importance. Two challenges have been overcome in this paper. First, each sensor is well scheduled for switching between recharging and working states for maintaining its perpetual lifetime since its battery is solar powered. Second, the sensors that are able to monitor the common target are well scheduled for cooperative sensing to maximize the surveillance quality since PSM is applied. Two efficient sensor schedules are proposed to maximize the surveillance quality of the bottleneck target which has the lowest surveillance quality. Performance study shows that the proposed mechanisms outperform the existing mechanisms in terms of Quality of Monitoring, Average utility, Fairness and Efficiency index.

关键词： Sensors Wireless sensor networks Batteries Surveillance Schedules Energy harvesting Energy harvesting scheduling solar power target coverage wireless sensor networks

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Verification and dosimetric impact of Acuros XB algorithm on intensity modulated stereotactic radiotherapy for locally persistent nasopharyngeal carcinoma

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MEDICAL PHYSICS 2012年第8期39卷 4705-4714页

作者： Kan, Monica W. K. Leung, Lucullus H. T. Yu, Peter K. N. Princess Margaret Hosp Dept Oncol Hong Kong Hong Kong Peoples R China City Univ Hong Kong Dept Phys & Mat Sci Kowloon Tong Hong Kong Peoples R China

Purpose: The main aim of the current study was to assess the dosimetric impact on intensity modulated stereotactic radiotherapy (IMSRT) for locally persistent nasopharyngeal carcinoma (NPC) due to the recalculation from the Anisotropic Analytical Algorithm (AAA) to the recently released Acuros XB (AXB) algorithm. The dosimetric accuracy of using AXB in predicting air/tissue interface doses from an open single small field in a simple geometric phantom and intensity modulated small fields in an anthropomorphic phantom was also investigated. Methods: The central axis percentage depth doses (PDD) of a rectangular phantom containing an air cavity were calculated by both AAA and AXB from 6 MV beam with small field sizes (2 x 2 to 5 x 5 cm(2)). These data were compared to PDD measured by thin thermoluminescent dosimeters (TLDs) and Monte Carlo simulations. The doses predicted by AAA and AXB near air/tissue interfaces from five different IMSRT plans were compared to the TLD measured doses in an anthropomorphic phantom. The PTV coverage, conformity and doses to organs at risk (OARs) calculated by AAA and AXB were compared for 12 patients, using identical beam setup, leaves movement and monitor units. Results: Testing using the simple rectangular phantom demonstrated that AAA and AXB overestimated the PDD at the air/tissue interfaces by up to 41% and 6%, respectively, from a 2 x 2 cm(2) field. The secondary build-up curves predicted by AXB caught up well with the measured data at around 2 mm beyond the air cavity. Testing using the anthropomorphic phantom showed that AAA overestimated the doses by up to 10%, while the measured doses matched those of the AXB to within 3%. Using AAA, the planning target coverage represented by 100% of the reference dose was estimated to be 4% higher than using AXB. The averaged minimum dose to the PTV predicted by AAA was about 4% higher and OARs doses 3% to 6% higher compared to AXB. Conclusions: AXB should be used whenever possible as the sta

关键词： acuros XB algorithm stereotactic intensity modulated radiotherapy nasopharyngeal carcinoma target coverage verification

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Minimizing movement for network connectivity in mobile sensor networks: an adaptive approach

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CLUSTER COMPUTING-THE JOURNAL OF NETWORKS SOFTWARE TOOLS AND APPLICATIONS 2019年第1期22卷 1373-1383页

作者： Jagtap, Arvind Madhukar Gomathi, N. VEL TECH Dr RR & Dr SR Tech Univ Chennai 600062 Tamil Nadu India

Nowadays the most important key point in the design of wireless sensor networks (WSNs) is the sensor coverage point and network connectivity. The main practical issue in designing the essential WSN is the mobility of mobile sensors which consumes more power thereby reduces the network lifetime significantly. In order to avoid these problems, we have investigated the mobile sensor deployment (MSD) problem comprises of network connectivity and target coverage is resolved using Euclidean spanning tree model (ECST) and ECST-adaptive VABC (ECST-AVABC) method respectively. Besides, we proposed an AVABC optimization algorithm by obtaining minimum movement of mobile sensors over the network. Furthermore, the extensive simulation experiments have offered the optimal promising solutions of NCON, to the MSD problem with minimum movement and providing the extended lifetime of WSN. Finally, the experimental results states that the movement distance shown by the proposed ECST-AVABC become 4.2, 10, and 20% lesser than the standard ECST-VABC method.

关键词： Wireless sensor networks target coverage Network connectivity Connecting nodes coverage sensor nodes Sink Energy consumption

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Approximation algorithms for maximum weighted target cover problem with distance limitations

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JOURNAL OF COMBINATORIAL OPTIMIZATION 2024年第4期47卷 1-14页

作者： Jin, Jianhong Ran, Yingli Zhang, Zhao Zhejiang Normal Univ Sch Math Sci Jinhua 321004 Zhejiang Peoples R China

In this paper, we study approximation algorithms for the problem of maximum weighted target cover with distance limitations (MaxWTCDL). Given n targets T={t(1),t(2),...,t(n)}on the plane and m mobile sensors S={s(1),s(2),...,s(m)} randomly deployed on the plane, each target t(i) has a weight w(i) and the sensing radius of the mobile sensors is r(s), suppose there is a movement distance constraint b for each sensor and a total movement distance constraint B, where B > b, the goal of MaxWTCDL is to move the mobile sensors within the distance constraints b and B to maximize the weight of covered targets. We present two polynomial time approximation algorithms. One is greedy-based, achieving approximation ratio (1)/(2v) in time O(mn(2)), where v = inverted right perpendicular(mb)/(B-b)inverted left perpendicular. The other is LP-based, achieving approximation ratio (1)/(v)(1-e(-1)) in time T-LP, where T-LP is the time needed to solve the linear program.

关键词： target coverage Distance constraint Approximation algorithm

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Performance evaluation of sensor deployment using optimization techniques and scheduling approach for K-coverage in WSNs

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WIRELESS NETWORKS 2018年第3期24卷 683-693页

作者： Krishnan, Muralitharan Rajagopal, Vishnuvarthan Rathinasamy, Sakthivel Sri Ramakrishna Inst Technol Dept Math Coimbatore 641010 Tamil Nadu India Anna Univ Dept Comp Sci Reg Ctr Coimbatore 641047 Tamil Nadu India Sungkyunkwan Univ Dept Math Suwon 440746 South Korea

In the wireless sensor networks, sensor deployment and coverage are the vital parameter that impacts the network lifetime. Network lifetime can be increased by optimal placement of sensor nodes and optimizing the coverage with the scheduling approach. For sensor deployment, heuristic algorithm is proposed which automatically adjusts the sensing range with overlapping sensing area without affecting the high degree of coverage. In order to demonstrate the network lifetime, we propose a new heuristic algorithm for scheduling which increases the network lifetime in the wireless sensor network. Further, the proposed heuristic algorithm is compared with the existing algorithms such as ant colony optimization, artificial bee colony algorithm and particle swarm optimization. The result reveals that the proposed heuristic algorithm with adjustable sensing range for sensor deployment and scheduling algorithm significantly increases the network lifetime.

关键词： Scheduling Sensing range Sensor deployment target coverage Wireless sensor networks

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Vertex coloring approach for Q-coverage problem in wireless sensor network

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JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2021年第5期40卷 8683-8695页

作者： Arivudainambi, D. Pavithra, R. Anna Univ Dept Math Chennai 600025 Tamil Nadu India

Wireless Sensor Network (WSN) has emerged recently due to its advancements and applications in various scientific and industrial fields. WSN consists a set of low cost and readily deployable sensors to monitor targets and recognise the physical phenomena. The principal challenge in WSN is to deploy these sensor nodes in optimal positions to achieve efficient network. Such network should satisfy the quality of service requirements in order to achieve high performance levels. Hence, this paper focuses on target Q-coverage problem where each target requires different number of sensors to monitor them. A Sequential Vertex Coloring based Sensor Placement (SVC-SP) algorithm is proposed to determine the number of sensors required and its optimal spot to satisfy the coverage quality requirement. The SVC-SP algorithm determines sensor requirement by partitioning the target set into independent subsets depending on the target's position and the sensor's sensing range. Each independent set consists set of targets that are nearer in the network such that a common sensor is sufficient to monitor them. The cardinality of such independent subsets provides the sensor requirement for target coverage. The optimal spot for each target is determined by the mean positioning of the targets in each independent set. This process is repeated until the q-requirement for each target is satisfied. Further, to improve the optimal spot for sensors, the random based SVC-SP algorithm, cuckoo search based SVC-SP algorithm and the genetic algorithm based SVC-SP algorithm are utilized. The simulation results show that genetic algorithm based SVC-SP algorithm performs better than other existing algorithms.

关键词： Optimal sensor placement target coverage Q-coverage vertex coloring sequential vertex coloring

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Are multiple CT scans required for planning curative radiotherapy in lung tumors of the lower lobe?

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INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 2003年第5期55卷 1394-1399页

作者： De Koste, JRV Lagerwaard, FJ de Boer, HCJ Nijssen-Visser, MR Senan, S Erasmus Med Ctr Dept Radiat Oncol Rotterdam Netherlands Erasmus Med Ctr Div Clin Phys Rotterdam Netherlands

Purpose: Lung tumors located in the lower lobe are the most mobile. Multiple computed tomographic (CT) scans, which had been performed for radiotherapy planning, were analyzed to determine the minimal number of required scans. Methods and Materials: Six spiral CT scans (3 rapid and 3 slow) from 7 such patients were coregistered. Reproducibility of target volumes was defined as the ratio between the overlapping and encompassing volume (COM/SUM) from scans derived using one technique. Volumetric and dosimetric analyses were performed. Results: Slow CT scans generated larger and more reproducible target volumes than rapid planning scans, with a mean COM/SUM ratio of 71.9 +/- 8.7% and 58.0 +/- 12.7%, respectively. When only a single slow CT scan was used for planning, the addition of a symmetrical 3D margin of 5 mm ensured 99% coverage of the "optimal" target volume, which was derived from summation of target volumes from all six scans. Conclusions: Planning target volumes (PTVs) derived from a single slow CT scan plus a 5-nun margin covered the "optimal" PTVs generated from six scans. Although these "slow PTVs" were larger, the increase in V-20 (the volume of lung tissue receiving a dose greater than or equal to 20 Gy) was limited. This indicates that only two CT scans, i.e., a full rapid scan of the entire thorax and a limited slow scan, are necessary for treatment planning in peripheral lung cancers. (C) 2003 Elsevier Science Inc.

关键词： lung cancer tumor mobility slow CT scans radiotherapy planning target coverage

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Solving coverage problems in wireless sensor networks using cover sets

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AD HOC NETWORKS 2010年第4期8卷 400-415页

作者： Zorbas, Dimitrios Glynos, Dimitris Kotzanikolaou, Panayiotis Douligeris, Christos Univ Piraeus Dept Informat Piraeus 18534 Greece

To achieve power efficient monitoring of targets by sensor networks, various coverage algorithms have been proposed. These algorithms divide the sensor nodes into cover sets, where each cover set is capable of monitoring all targets. Generating the maximum number of cover sets has been proven to be an NP-complete problem and, thus, algorithms producing sub-optimal solutions have been proposed. In this paper we present a novel and efficient coverage algorithm, that can produce both disjoint cover sets, i.e. cover sets with no common sensor nodes, as well as non-disjoint cover sets. While searching for the best sensor to include in a cover set, our algorithm uses a cost function that takes into account the monitoring capabilities of a sensor, its association with Poorly monitored targets, but also the sensor's remaining battery life. Through simulations, we show that the proposed algorithm outperforms similar heuristic algorithms found in the literature, producing collections of cover sets of optimal (or near-optimal) size. The increased availability offered by these cover sets along with the short execution time of the proposed algorithm make it desirable for a wide range of node deployment environments. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Wireless sensor networks target coverage Cover sets Centralised algorithm

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targeted analysis of nucleotide and copy number variation by exon capture in allotetraploid wheat genome

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GENOME BIOLOGY 2011年第9期12卷 1-17页

作者： Saintenac, Cyrille Jiang, Dayou Akhunov, Eduard D. Kansas State Univ Throckmorton Plant Sci Ctr Manhattan KS 66506 USA

Background: The ability of grass species to adapt to various habitats is attributed to the dynamic nature of their genomes, which have been shaped by multiple rounds of ancient and recent polyploidization. To gain a better understanding of the nature and extent of variation in functionally relevant regions of a polyploid genome, we developed a sequence capture assay to compare exonic sequences of allotetraploid wheat accessions. Results: A sequence capture assay was designed for the targeted re-sequencing of 3.5 Mb exon regions that surveyed a total of 3,497 genes from allotetraploid wheat. These data were used to describe SNPs, copy number variation and homoeologous sequence divergence in coding regions. A procedure for variant discovery in the polyploid genome was developed and experimentally validated. About 1% and 24% of discovered SNPs were loss-of-function and non-synonymous mutations, respectively. Under-representation of replacement mutations was identified in several groups of genes involved in translation and metabolism. Gene duplications were predominant in a cultivated wheat accession, while more gene deletions than duplications were identified in wild wheat. Conclusions: We demonstrate that, even though the level of sequence similarity between targeted polyploid genomes and capture baits can bias enrichment efficiency, exon capture is a powerful approach for variant discovery in polyploids. Our results suggest that allopolyploid wheat can accumulate new variation in coding regions at a high rate. This process has the potential to broaden functional diversity and generate new phenotypic variation that eventually can play a critical role in the origin of new adaptations and important agronomic traits.

关键词： Copy Number Variation Wheat Genome Whole Genome Duplication Tetraploid Wheat target coverage

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