Since wireless links in Ad hoc networks are more fragile than those in traditional wireless networks due to route flapping,multi-node cooperation plays an important role in ensuring the quality of service( QoS). Based...Since wireless links in Ad hoc networks are more fragile than those in traditional wireless networks due to route flapping,multi-node cooperation plays an important role in ensuring the quality of service( QoS). Based on the authors' previous work,this paper proposes a receiver-controlled multi-node cooperation routing protocol,known as AODV-RCC. In this protocol,nodes form a cooperation group based on signal power. In a cooperation group,signal power between a partner and a transmitter,as well as signal power between the partner and the receiver,must be larger than the signal power between the transmitter and the receiver. Otherwise,the transmission will not benefit from cooperation. To avoid collision or congestion,each cooperation group only contains one partner. This partner offers both data and ACK cooperative retransmission. Its retransmission time should be shorter than the internal retry time of the transmitter's MAC layer,because it is better for the partner to retransmit firstly,as it offers a more reliable cooperative link. In AODV-RCC,it is the receiver that chooses the partner,because the link between the partner and the receiver is the most important. According to our simulation results,AODV-RCC shortens the end-to-end delay and increases the packet delivery ratio.展开更多
Closed form expressions for the PDF and MGF of the harmonic mean of two independent exponential variates are cited and derived, and then applied to study the performance of cellular multi-node and dual-hop cooperative...Closed form expressions for the PDF and MGF of the harmonic mean of two independent exponential variates are cited and derived, and then applied to study the performance of cellular multi-node and dual-hop cooperative communication systems with non-regenerative relays over flat Rayleigh fading channels. We derive the probability density function (PDF) and asymptotic symbol error rate (SER) expression with MRC scheme. Then we use Matlab to simulate the performance.展开更多
In view of the obvious changes in color between the upper and lower leaf scar in sugarcane nodes,a method of simultaneous multi-nodes identification on a single sugarcane stem was proposed based on the analysis of gra...In view of the obvious changes in color between the upper and lower leaf scar in sugarcane nodes,a method of simultaneous multi-nodes identification on a single sugarcane stem was proposed based on the analysis of gradient characteristics of sugarcane images.In combination with image processing and machine vision recognition technology,two cameras were used to acquire different parts of sugarcane images,and the two images were integrated into a complete image of sugarcane by image mosaicking.The Sobel operator is used to calculate the gradient of the sugarcane image in a horizontal direction,and the gradient image is obtained.The sugarcane gradient image was scanned by a rectangular template with a width of 14 pixels and a step length of 12 pixels.The features of average gradient and variance gradient were used to identify sugarcane nodes for the first time.The experimental results showed that the recognition accuracy was 96.8952%,and there were fewer false detected sugarcane segments.The detection efficiency could be improved by detecting multi-nodes on a single sugarcane stem at the same time.展开更多
近年来,节点地震采集技术发展迅速,在油气勘探中得到大规模推广应用。相对于有缆地震仪器,节点地震仪在带道能力、排列布设以及施工效率等方面具有显著的优势,但它无法实时获取采集的地震数据,给质量监控和数据评价带来一定困难。如何...近年来,节点地震采集技术发展迅速,在油气勘探中得到大规模推广应用。相对于有缆地震仪器,节点地震仪在带道能力、排列布设以及施工效率等方面具有显著的优势,但它无法实时获取采集的地震数据,给质量监控和数据评价带来一定困难。如何确保节点地震采集质量,保证节点地震仪工作状态良好成为采集施工中的重要环节,即保证设备的稳定性与安全性。结合野外地震采集施工模式和作业流程,介绍了多类型节点质控手机APP及质控数据综合分析平台设计思路,开展了节点通讯、手机定位及导航、节点位置监控、多模式巡检、数据可视化及统计分析等关键技术研究,并基于Visual Studio 2022集成开发环境,采用MVC设计模式研发了多类型节点质控手机APP及质控数据综合分析平台,解决了当前节点质控软件通用性不强,质控数据综合评价分析自动化程度低等问题。在实际生产应用中,软件性能稳定、运行流畅,大幅提高了节点地震仪质控效率及效果,可有效保障节点数据采集质量和资料品质,降低施工成本。展开更多
基金Sponsored by the Natural Scientific Research Innovation Foundation in Harbin Institute of Technology(Grant No.HIT.NSRIF.2013029)the National Science and Technology Major Project(Grant No.2012ZX03004003)+1 种基金the National Basic Research Development Program of China(973 Program)(Grant No.2013CB329003)the National Natural Science Foundation of China(Grant No.61201148 and No.61101123)
文摘Since wireless links in Ad hoc networks are more fragile than those in traditional wireless networks due to route flapping,multi-node cooperation plays an important role in ensuring the quality of service( QoS). Based on the authors' previous work,this paper proposes a receiver-controlled multi-node cooperation routing protocol,known as AODV-RCC. In this protocol,nodes form a cooperation group based on signal power. In a cooperation group,signal power between a partner and a transmitter,as well as signal power between the partner and the receiver,must be larger than the signal power between the transmitter and the receiver. Otherwise,the transmission will not benefit from cooperation. To avoid collision or congestion,each cooperation group only contains one partner. This partner offers both data and ACK cooperative retransmission. Its retransmission time should be shorter than the internal retry time of the transmitter's MAC layer,because it is better for the partner to retransmit firstly,as it offers a more reliable cooperative link. In AODV-RCC,it is the receiver that chooses the partner,because the link between the partner and the receiver is the most important. According to our simulation results,AODV-RCC shortens the end-to-end delay and increases the packet delivery ratio.
文摘Closed form expressions for the PDF and MGF of the harmonic mean of two independent exponential variates are cited and derived, and then applied to study the performance of cellular multi-node and dual-hop cooperative communication systems with non-regenerative relays over flat Rayleigh fading channels. We derive the probability density function (PDF) and asymptotic symbol error rate (SER) expression with MRC scheme. Then we use Matlab to simulate the performance.
文摘In view of the obvious changes in color between the upper and lower leaf scar in sugarcane nodes,a method of simultaneous multi-nodes identification on a single sugarcane stem was proposed based on the analysis of gradient characteristics of sugarcane images.In combination with image processing and machine vision recognition technology,two cameras were used to acquire different parts of sugarcane images,and the two images were integrated into a complete image of sugarcane by image mosaicking.The Sobel operator is used to calculate the gradient of the sugarcane image in a horizontal direction,and the gradient image is obtained.The sugarcane gradient image was scanned by a rectangular template with a width of 14 pixels and a step length of 12 pixels.The features of average gradient and variance gradient were used to identify sugarcane nodes for the first time.The experimental results showed that the recognition accuracy was 96.8952%,and there were fewer false detected sugarcane segments.The detection efficiency could be improved by detecting multi-nodes on a single sugarcane stem at the same time.
文摘近年来,节点地震采集技术发展迅速,在油气勘探中得到大规模推广应用。相对于有缆地震仪器,节点地震仪在带道能力、排列布设以及施工效率等方面具有显著的优势,但它无法实时获取采集的地震数据,给质量监控和数据评价带来一定困难。如何确保节点地震采集质量,保证节点地震仪工作状态良好成为采集施工中的重要环节,即保证设备的稳定性与安全性。结合野外地震采集施工模式和作业流程,介绍了多类型节点质控手机APP及质控数据综合分析平台设计思路,开展了节点通讯、手机定位及导航、节点位置监控、多模式巡检、数据可视化及统计分析等关键技术研究,并基于Visual Studio 2022集成开发环境,采用MVC设计模式研发了多类型节点质控手机APP及质控数据综合分析平台,解决了当前节点质控软件通用性不强,质控数据综合评价分析自动化程度低等问题。在实际生产应用中,软件性能稳定、运行流畅,大幅提高了节点地震仪质控效率及效果,可有效保障节点数据采集质量和资料品质,降低施工成本。
