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Reuse Partitioning-Based Frequency Assignment in Fixed Two-Hop Relay Cellular Network
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作者 刘涛 戎蒙恬 史宏逵 《Transactions of Tianjin University》 EI CAS 2007年第3期220-225,共6页
In relay cellular network, relay links will consume extra frequency resources, which makes radio resource allocation become more complex and important. A new frequency allocation scheme is proposed to increase cell ca... In relay cellular network, relay links will consume extra frequency resources, which makes radio resource allocation become more complex and important. A new frequency allocation scheme is proposed to increase cell capacity and improve signal-to-interference ratio (SIR) of users located at cell edges. By dividing cell into different parts and configuring each of these parts with a unique reuse factor, this scheme improves spectral utilization efficiency and avoids inter-cell interference effectively. Optimal combinations of reuse factors and locations of relay nodes are also addressed and investigated. Computer simulation results show that, by employing the proposed scheme, maximum cell capacity gains of about 50%, 35% and 30% can be achieved in comparison with conventional cellular network scheme, traditional reuse partitioning scheme and reuse-adjacent-cell-frequencies scheme, respectively. Moreover, since in the proposed scheme resources are dynamically allocated among relay nodes, more benefits can be obtained in comparison with fixed resource allocation schemes under non-uniform traffic distribution. 展开更多
关键词 继电器 无线电 电子网络 隔离物
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Optimization of Cooperative RelayingMolecular Communications for Nanomedical Applications
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作者 Eman S.Attia Ashraf A.M.Khalaf +4 位作者 Fathi E.Abd El-Samie Saied M.Abd El-atty Konstantinos A.Lizos Osama Alfarraj Heba M.El-Hoseny 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第2期1259-1275,共17页
Recently,nano-systems based on molecular communications via diffusion(MCvD)have been implemented in a variety of nanomedical applications,most notably in targeted drug delivery system(TDDS)scenarios.Furthermore,becaus... Recently,nano-systems based on molecular communications via diffusion(MCvD)have been implemented in a variety of nanomedical applications,most notably in targeted drug delivery system(TDDS)scenarios.Furthermore,because the MCvD is unreliable and there exists molecular noise and inter symbol interference(ISI),cooperative nano-relays can acquire the reliability for drug delivery to targeted diseased cells,especially if the separation distance between the nano transmitter and nano receiver is increased.In this work,we propose an approach for optimizing the performance of the nano system using cooperative molecular communications with a nano relay scheme,while accounting for blood flow effects in terms of drift velocity.The fractions of the molecular drug that should be allocated to the nano transmitter and nano relay positioning are computed using a collaborative optimization problem solved by theModified Central Force Optimization(MCFO)algorithm.Unlike the previous work,the probability of bit error is expressed in a closed-form expression.It is used as an objective function to determine the optimal velocity of the drug molecules and the detection threshold at the nano receiver.The simulation results show that the probability of bit error can be dramatically reduced by optimizing the drift velocity,detection threshold,location of the nano-relay in the proposed nano system,and molecular drug budget. 展开更多
关键词 Nanomedical system molecular communication cooperative relay OPTIMIZATION
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Coordinated responses of leaf and nodule traits contribute to the accumulation of N in relay intercropped soybean
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作者 Ping Chen Qing Du +8 位作者 Benchuan Zheng Huan Yang Zhidan Fu Kai Luo Ping Lin Yilin Li Tian Pu Taiwen Yong Wenyu Yang 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2024年第6期1910-1928,共19页
Maize(Zea mays L.)-soybean(Glycine max L.Merr.)relay intercropping provides a way to enhance land productivity.However,the late-planted soybean suffers from shading by the maize.After maize harvest,how the recovery gr... Maize(Zea mays L.)-soybean(Glycine max L.Merr.)relay intercropping provides a way to enhance land productivity.However,the late-planted soybean suffers from shading by the maize.After maize harvest,how the recovery growth influences the leaf and nodule traits remains unclear.A three-year field experiment was conducted to evaluate the effects of genotypes,i.e.,supernodulating(nts1007),Nandou 12(ND12),and Guixia 3(GX3),and crop configurations,i.e.,the interspecific row spacing of 45(I45),60(I60),75 cm(I75),and sole soybean(SS),on soybean recovery growth and N fixation.The results showed that intercropping reduced the soybean total leaf area(LA)by reducing both the leaf number(LN)and unit leaflet area(LUA),and it reduced the nodule dry weight(NW)by reducing both the nodule number(NN)and nodule diameter(ND)compared with the SS.The correlation and principal component analysis(PCA)indicated a co-variability of the leaf and nodule traits in response to the genotype and crop configuration interactions.During the recovery growth stages,the compensatory growth promoted soybean growth to reduce the gaps of leaf and nodule traits between intercropping and SS.The relative growth rates of ureide(RGR_U)and nitrogen(RGR_N)accumulation were higher in intercropping than in SS.Intercropping achieved more significant sucrose and starch contents compared with SS.ND12 and GX3 showed more robust compensatory growth than nts1007 in intercropping.Although the recovery growth of relay intercropping soybean improved biomass and nitrogen accumulation,ND12 gained a more significant partial land equivalent ratio(pLER)than GX3.The I60 treatment achieved more robust compensation effects on biomass and N accumulation than the other configurations.Meanwhile,I60 showed a higher nodule sucrose content and greater shoot ureide and N accumulation than SS.Finally,intercropping ND12 with maize using an interspecific row spacing of 60 cm was optimal for both yield advantage and N accumulation. 展开更多
关键词 relay intercropping GENOTYPE crop configuration symbiotic nitrogen fixation SOYBEAN NODULE
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Security-Reliability Tradeoff Analysis for Jamming Aided Decode-and-Forward Relay Networks
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作者 Zou Ronggui Zou Yulong +1 位作者 Zhu Jia Li Bin 《China Communications》 SCIE CSCD 2024年第5期218-228,共11页
In this paper,we explore a cooperative decode-and-forward(DF)relay network comprised of a source,a relay,and a destination in the presence of an eavesdropper.To improve physical-layer security of the relay system,we p... In this paper,we explore a cooperative decode-and-forward(DF)relay network comprised of a source,a relay,and a destination in the presence of an eavesdropper.To improve physical-layer security of the relay system,we propose a jamming aided decodeand-forward relay(JDFR)scheme combining the use of artificial noise and DF relaying which requires two stages to transmit a packet.Specifically,in stage one,the source sends confidential message to the relay while the destination acts as a friendly jammer and transmits artificial noise to confound the eavesdropper.In stage two,the relay forwards its re-encoded message to the destination while the source emits artificial noise to confuse the eavesdropper.In addition,we analyze the security-reliability tradeoff(SRT)performance of the proposed JDFR scheme,where security and reliability are evaluated by deriving intercept probability(IP)and outage probability(OP),respectively.For the purpose of comparison,SRT of the traditional decode-and-forward relay(TDFR)scheme is also analyzed.Numerical results show that the SRT performance of the proposed JDFR scheme is better than that of the TDFR scheme.Also,it is shown that for the JDFR scheme,a better SRT performance can be obtained by the optimal power allocation(OPA)between the friendly jammer and user. 展开更多
关键词 decode-and-forward relay friendly jammer physical layer security power allocation security-reliability tradeoff
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Average Secrecy Capacity of the Reconfigurable Intelligent Surface-Assisted Integrated Satellite Unmanned Aerial Vehicle Relay Networks
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作者 Ping Li Kefeng Guo +2 位作者 Feng Zhou XuelingWang Yuzhen Huang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第2期1849-1864,共16页
Integrated satellite unmanned aerial vehicle relay networks(ISUAVRNs)have become a prominent topic in recent years.This paper investigates the average secrecy capacity(ASC)for reconfigurable intelligent surface(RIS)-e... Integrated satellite unmanned aerial vehicle relay networks(ISUAVRNs)have become a prominent topic in recent years.This paper investigates the average secrecy capacity(ASC)for reconfigurable intelligent surface(RIS)-enabled ISUAVRNs.Especially,an eve is considered to intercept the legitimate information from the considered secrecy system.Besides,we get detailed expressions for the ASC of the regarded secrecy system with the aid of the reconfigurable intelligent.Furthermore,to gain insightful results of the major parameters on the ASC in high signalto-noise ratio regime,the approximate investigations are further gotten,which give an efficient method to value the secrecy analysis.At last,some representative computer results are obtained to prove the theoretical findings. 展开更多
关键词 Integrated satellite unmanned aerial vehicle relay networks reconfigurable intelligent surface average secrecy capacity(ASC) asymptotic ASC
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Resource scheduling scheme with QoS support in two-hop relay-enhanced OFDMA systems 被引量:1
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作者 LIU Wei ,JI Hong,LI Ting School of Information and Telecommunication Engineering,Beijing University of Posts and Telecommunications,Beijing 100876,China 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2010年第4期26-30,共5页
As the system performance is obviously improved by introducing the concept of relay into the traditional orthogonal frequency division multiple access (OFDMA) systems, resource scheduling in relay-enhanced OFDMA sys... As the system performance is obviously improved by introducing the concept of relay into the traditional orthogonal frequency division multiple access (OFDMA) systems, resource scheduling in relay-enhanced OFDMA systems is worthy of being studied carefully. To solve the optimization problem of achieving the maximum throughput while satisfying the quality of service (QoS) and guaranteeing the fairness of users, a novel resource scheduling scheme with QoS support for the downlink of two-hop relay-enhanced OFDMA systems is proposed. The proposed scheme, which is considered both in the first time sub-slot between direct link users and relay stations, and the second time sub-slot among relay link users, takes QoS support into consideration, as well as the system throughput and the fairness for users. Simulation results show that the proposed scheme has good performance in maximizing system throughput and guaranteeing the performance in the service delay and the data loss rate. 展开更多
关键词 relay OFDMA QOS resource scheduling
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Covert Communication with a Spectrum Sharing Relay in the Finite Blocklength Regime 被引量:3
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作者 Ruiqian Ma Weiwei Yang +2 位作者 Hui Shi Xingbo Lu Jue Liu 《China Communications》 SCIE CSCD 2023年第4期195-211,共17页
In this paper,we investigate the feasibility and performance of the covert communication with a spectrum sharing relay in the finite blocklength regime.Specifically,the relay opportunistically forwards the source'... In this paper,we investigate the feasibility and performance of the covert communication with a spectrum sharing relay in the finite blocklength regime.Specifically,the relay opportunistically forwards the source's messages to the primary receiver or conveys the covert messages to its own receiver via the sharing spectrum,while the warden attempts to detect the transmission.First,we derive a lower bound on the covertness constraint,and the analytical expressions of both the primary average effective covert throughput(AECT)and sum AECT are presented by considering the overall decoding error performance.Then,we formulate two optimization problems to maximize the primary and sum AECT respectively by optimizing the blocklength and the transmit power at the source and the relay.Our examinations show that there exists an optimal blocklength to maximize the primary and sum AECT.Besides,it is revealed that,to maximize the primary AECT,the optimal transmit power of each hop increases as its channel quality deteriorates.Furthermore,in the optimization for maximizing the sum AECT,the optimal transmit power at the source equals to zero when the channel quality from relay to the secondary receiver is not weaker than that from relay to the primary receiver. 展开更多
关键词 covert communication finite blocklength relay spectrum sharing
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Two-Hop Gaussian Relay Channel with Linear Relaying: Achievable Rate and Optimization Design 被引量:1
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作者 Deng Zhixiang Wang Baoyun +2 位作者 Lang Fei Ma Yayan Liu Chen 《China Communications》 SCIE CSCD 2012年第2期96-104,共9页
The relay node with linear relaying transmits the linear combination of its past received signals.The optimization of two-hop relay channel with linear relaying is discussed in this paper.The capacity for the two-hop ... The relay node with linear relaying transmits the linear combination of its past received signals.The optimization of two-hop relay channel with linear relaying is discussed in this paper.The capacity for the two-hop Gaussian relay channel with linear relaying is derived,which can be formulated as an optimization problem over the relaying matrix and the covariance matrix of the signals transmitted at the source.It is proved that the solution to this optimization problem is equivalent to a "single-letter" optimization problem.We also show that the solution to this "single-letter" optimization problem has the same form as the expression of the rate achieved by Time-Sharing Amplify and Forward(TSAF).In order to solve this equivalent problem,we proposed an iterative algorithm.Simulation results show that if channel gain of one hop is relatively smaller,the achievable rate with TSAF is closer to the max-flow min-cut capacity bound,but at a lower complexity. 展开更多
关键词 中继信道 线性组合 优化设计 高斯 协方差矩阵 优化问题 速率 容量约束
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Optimal Positions of Relay Stations for Cluster-Based Two-Hop Cellular Network
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作者 Hrishikesh VENKATARAMAN Pradeep Kumar JAIN Segu REVANTH 《International Journal of Communications, Network and System Sciences》 2009年第4期283-292,共10页
Multihop cellular networks is an exciting and a fledgling area of wireless communication which offers huge potential in terms of coverage enhancement, data-rates, power reduction, and various other quality of service ... Multihop cellular networks is an exciting and a fledgling area of wireless communication which offers huge potential in terms of coverage enhancement, data-rates, power reduction, and various other quality of service improvements. However, resource allocation in MCN is an NP-hard problem. Hence, significant research needs to be done in this field in order to efficiently design the radio network. In this paper, optimal position of relay stations in a hierarchical cluster-based two-hop cellular network is investigated. Vector algebra has been used to derive general equation for carrier-to-interference ratio (C/I) of a mobile station. It has been observed that when the transmit power of base station (BS) and the gateway (GTW)/relay station (RS) are same, the RSs should be located close to mid-point of BS and the edge of the cell. However, significantly, when the transmit power of the BS is greater than that of the GTW, then the RSs should be placed closer to the edge of the cell, in order to maximize the minimum C/I at any point in the cell. This in turn results in higher modulation technique at the physical layer, and hence, a higher data-rate to all the users in the system. 展开更多
关键词 Cluster-Based Design Power Control relay STATIONS two-hop CELLULAR
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The Improvement of Relay Selection Schemes in Two-Hop Cellular Networks
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作者 Hua Wu 《International Journal of Communications, Network and System Sciences》 2017年第8期98-107,共10页
In wireless networks, cooperative relaying could improve throughput by exploiting diversity. In order to reduce the amount of feedback for the channel gain, a semi-distributed scheme based on the relay feasible condit... In wireless networks, cooperative relaying could improve throughput by exploiting diversity. In order to reduce the amount of feedback for the channel gain, a semi-distributed scheme based on the relay feasible condition is proposed. Each relay node can measure its backward and forward channel gains. If both the channel gains are larger than a pre-defined threshold, this relay node is feasible. The final decision on the best relay selection is still given by the base station. Besides, the switch-and-examine relay selection scheme, which selects the first feasible relay node, is also investigated. Simulation results are presented to illustrate the advantage of two proposed schemes. 展开更多
关键词 relay Selection COOPERATIVE relayING AMPLIFY-AND-FORWARD CELLULAR Networks
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A fixed clustering protocol based on random relay strategy for EHWSN 被引量:2
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作者 Xianquan Luoa Chunjiong Zhang Longju Bai 《Digital Communications and Networks》 SCIE CSCD 2023年第1期90-100,共11页
In Energy Harvesting Wireless Sensor Networks(EHWSN),the communication protocol will directly affect the final performance of the network,so it is necessary to study the communication protocol based on EHWSN.In this p... In Energy Harvesting Wireless Sensor Networks(EHWSN),the communication protocol will directly affect the final performance of the network,so it is necessary to study the communication protocol based on EHWSN.In this paper,for the low-cost fixed clustering problem,a fixed clustering protocol RRCEH is based on random relaying.Our proposed RRCEH abandons the inefficient inter-cluster communication method of the traditional fixed clustering protocol.To coordinate the data upload of the cluster head,RRCEH allocates different random relay vectors to each ring area of the network,and combines all the random relay vectors into a random relay matrix of RRCEH.In each communication round,the cluster head node randomly selects its relay target node to send data according to the probability distribution in the random relay vector in the area.For two different cluster head configuration scenarios,by optimizing the random relay matrix,RRCEH can effectively reduce the network's configuration requirements for cluster head energy harvesting capability,thus reducing the deployment cost of EHWSN. 展开更多
关键词 Energy harvesting Wireless sensor networks Clustering protocol Random relay strategy
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Arbitrary Decode-Forward Relaying with Re-Encoded Bits Selection Strategy for Polar Codes
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作者 Di Guan Kai Niu Chao Dong 《China Communications》 SCIE CSCD 2023年第8期153-162,共10页
In this paper,we propose an arbitrary decode-forward single-relay scheme for finite blocklength polar codes,which can be applied to the general symmetric discrete memoryless relay channel with orthogonal receiver comp... In this paper,we propose an arbitrary decode-forward single-relay scheme for finite blocklength polar codes,which can be applied to the general symmetric discrete memoryless relay channel with orthogonal receiver components.The relay node decodes the received message.The relay node selectively re-encodes the message and transmits it to the destination node.Furthermore,in order to minimize the upper-bound of the block error probability,we propose a selection strategy to decide the proper re-encoded bit set by the relay.Simulation results are presented to illustrate the improvement in decoding performance of the proposed scheme compared to conventional relay schemes in both additive white Gaussian noise(AWGN)channel and Rayleigh fading channel(RFC). 展开更多
关键词 polar codes decode-and-forward relaying arbitrary relay channel block error rate estimation
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Throughput Analysis of HARQ Scheme Based on Full-Duplex Two-Way AF SWIPT Relay
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作者 Xiaoye Shi Fei Ding +2 位作者 Haiting Zhu Zhaowei Zhang Lei Zhang 《Computers, Materials & Continua》 SCIE EI 2023年第3期4819-4830,共12页
The simultaneous wireless information and power transfer(SWIPT)relay system is one of the emerging technologies.Xiaomi Corporation and Motorola Inc.recently launched indoor wireless power transfer equipment is one of ... The simultaneous wireless information and power transfer(SWIPT)relay system is one of the emerging technologies.Xiaomi Corporation and Motorola Inc.recently launched indoor wireless power transfer equipment is one of the most promising applications.To tap the potential of the system,hybrid automatic repeat request(HARQ)is introduced into the SWIPT relay system.Firstly,the time slot structure of HARQ scheme based on full duplex two-way amplify and forward(AF)SWIPT relay is given,and its retransmission status is analyzed.Secondly,the equivalent signal-to-noise ratio and outage probability of various states are calculated by approximate simplification.Thirdly,the energy harvesting power in each state is calculated.Finally,the energy harvested-throughput sum function is constructed to characterize the performance of energy harvesting and data transmission.Simulation results show that the proposed HARQ scheme has better energy harvestedthroughput sum function than the traditional HARQ scheme.When P_(2)=22 dB,the maximum sum function is 54.86%(the proposed HARQ scheme)and 52.307%(the traditional HARQ scheme),respectively. 展开更多
关键词 SWIPT relay HARQ THROUGHPUT full-duplex
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Solar Energy Harvesting Using a Timer-Based Relay Selection
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作者 Raed Alhamad Hatem Boujemaa 《Computers, Materials & Continua》 SCIE EI 2023年第1期2149-2159,共11页
In this paper,the throughput and delay of cooperative communications are derived when solar energy is used and relay node is selected using a timer.The source and relays harvest energy from sun using a photo voltaic s... In this paper,the throughput and delay of cooperative communications are derived when solar energy is used and relay node is selected using a timer.The source and relays harvest energy from sun using a photo voltaic system.The harvested power is used by the source to transmit data to the relays.Then,a selected relay amplifies the signal to the destination.Opportunistic,partial and reactive relay selection are used.The relay transmits when its timer elapses.The timer is set to a value proportional to the inverse of its Signal to Noise Ratio(SNR).Therefore,the relay with largest SNR will transmit first and its signal will be detected by the other relays that will remain idle to avoid collisions.Harvesting duration is optimized to maximize the throughput.Packet’s waiting time and total delay are also computed.We also derive the statistics of SNR when solar energy is used.The harvested power from sun is proportional to the sum of a deterministic radiation intensity and a random attenuation due to weather effects and clouds occlusion.The fixed radiation intensity depends on season,month and time t in hour.The throughput of cooperative communications with energy harvesting from sun was not yet studied. 展开更多
关键词 Solar energy harvesting timer based relay selection relaying techniques throughput and delay analysis
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Interference and Spectral Efficiency Analysis in Two-hop Cellular Network with Fixed Relays in FDD Mode 被引量:1
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作者 李平 戎蒙恬 +1 位作者 黄磊 喻丹 《Journal of Shanghai Jiaotong university(Science)》 EI 2006年第3期361-367,共7页
This paper presented a scheme of two-hop cellular network with fixed relay nodes (FRN). Based on this scheme, co-channel interference and signal interference ratio(SIR) received by base station(BS) and FRN were analyz... This paper presented a scheme of two-hop cellular network with fixed relay nodes (FRN). Based on this scheme, co-channel interference and signal interference ratio(SIR) received by base station(BS) and FRN were analyzed. Both the theoretical analysis and simulation results show that the SIR can be improved significantly when relays are employed in the network. The higher spectral efficiency can be obtained due to the improved two-hop link quality through the use of adaptive modulation and coding (AMC). The antenna height of FRN and the cell radius of BS and that of FRN influence SIR received by BS and FRN and the system spectral efficiency greatly. The proper antenna height of FRN and cell radius of BS and that of FRN were also given to get the highest spectral efficiency. 展开更多
关键词 固定继电器结点 信号干扰比 双重频率分割 细胞网络
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Selective synthesis of nitrate from air using a plasma-driven gas-liquid relay reaction system
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作者 Sibo Chen Kai Mei +2 位作者 Yaru Luo Liang-Xin Ding Haihui Wang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第10期439-446,I0012,共9页
The direct oxidation of nitrogen is a potential pathway to achieving the zero-carbon-emission synthesis of nitric acid or nitrate, because it does not involve ammonia synthesis and additional ammonia oxidation process... The direct oxidation of nitrogen is a potential pathway to achieving the zero-carbon-emission synthesis of nitric acid or nitrate, because it does not involve ammonia synthesis and additional ammonia oxidation processes. However, the slow kinetics of nitrogen oxidation and the difficult selective control of oxidation products hinder the development of this process. In this study, a plasma-driven gas-liquid relay reaction system was developed to overcome these limitations. A typical feature of this reaction system is that it can efficiently generate NO_x under plasma exposure;moreover, the specific anions in the absorption solution can be oxidized to strong oxidants capable of relay oxidation of low-valence nitrogen oxides. This feature allows for the deep oxidation of nitrogen, thus enabling the oxidation products of nitrogen to exist in high-valence states in the absorption solution. For experimental verification, we achieved the 100% selective synthesis of nitrate under plasma exposure, with air as the supply gas and a sodium sulfate solution as the absorption solution. 展开更多
关键词 Nitrogen oxidation Nitrate synthesis Plasma relay reaction High selectivity
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Secrecy Outage Probability for Two-Way Integrated Satellite Unmanned Aerial Vehicle Relay Networks with Hardware Impairments
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作者 Xiaoting Ren Kefeng Guo 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第6期2515-2530,共16页
In this paper,we investigate the secrecy outage performance for the two-way integrated satellite unmanned aerial vehicle relay networks with hardware impairments.Particularly,the closed-form expression for the secrecy... In this paper,we investigate the secrecy outage performance for the two-way integrated satellite unmanned aerial vehicle relay networks with hardware impairments.Particularly,the closed-form expression for the secrecy outage probability is obtained.Moreover,to get more information on the secrecy outage probability in a high signalto-noise regime,the asymptotic analysis along with the secrecy diversity order and secrecy coding gain for the secrecy outage probability are also further obtained,which presents a fast method to evaluate the impact of system parameters and hardware impairments on the considered network.Finally,Monte Carlo simulation results are provided to show the efficiency of the theoretical analysis. 展开更多
关键词 Integrated satellite unmanned aerial vehicle relay networks two-way unmanned aerial vehicle relay hardware impairments secrecy outage probability(SOP) asymptotic SOP
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Cooperative Relay Networks Based on the OAM Technique for 5G Applications
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作者 Mohammad Alkhawatrah Ahmad Alamayreh Nidal Qasem 《Computer Systems Science & Engineering》 SCIE EI 2023年第3期1911-1919,共9页
Orbital Angular Momentum(OAM)is an intrinsic property of electro-magnetic waves.Great research has been witnessed in the last decades aiming at exploiting the OAM wave property in different areas in radio and optics.O... Orbital Angular Momentum(OAM)is an intrinsic property of electro-magnetic waves.Great research has been witnessed in the last decades aiming at exploiting the OAM wave property in different areas in radio and optics.One pro-mising area of particular interest is to enhance the efficiency of the available communications spectrum.However,adopting OAM-based solutions is not priceless as these suffer from wave divergence especially when the OAM order is high.This shall limit the practical communications distance,especially in the radio regime.In this paper,we propose a cooperative OAM relaying system consisting of a source,relay,and destination.Relays help the source to transmit packets to the destination by providing an alternative connection between source and desti-nation.This cooperative solution aims on the one hand,through best-path selection,on increasing the communications range.On the other hand,through the parallel transmission orders allowed by OAM carrying waves,the system could raise its total transmission throughput.Simulation results show that combining a cooperative relay with OAM improves the system throughput compared to using each element separately.In addition,the proposed cooperative relaying OAM out-performs the cooperative relaying non-orthogonal multiple access scheme,which is a key spectrally efficient technique used in 5G technology. 展开更多
关键词 5G cooperative network OAM relay THROUGHPUT
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Blockchain Based Secure Relay Scheme for Space-Terrestrial Integrated Networks
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作者 Zhen Gao Jiuzhi Zhang +3 位作者 Dongbin Zhang Ailing Wang Chengkang Pan Xin Li 《China Communications》 SCIE CSCD 2023年第5期170-181,共12页
The future 6G networks will integrates space and terrestrial networks to realize a fully connected world with extensive collaboration.However,how to build trust between multiple parties is a difficult problem for secu... The future 6G networks will integrates space and terrestrial networks to realize a fully connected world with extensive collaboration.However,how to build trust between multiple parties is a difficult problem for secure cooperation without a reliable third-party.Blockchain is a promising technology to solve this problem by converting the trust between multi-parties to the trust to the common shared data.Several works have proposed to apply the incentive mechanism in blockchain to encourage effective cooperation,but how to evaluate the cooperation performance and avoid breach of contract is not discussed.In this paper,a secure relay scheme is proposed based on the consortium blockchain system composed by different operators.In particular,smart contract checks the integrity of the message based on RSA accumulator,and executes transactions automatically when the message is delivered successfully.Detailed procedures are introduced for both uplink and downlink relay.Implementation based on Hyperledger Fabric proves the effectiveness of the proposed scheme and shows that the complexity of the scheme is low enough for practical deployment. 展开更多
关键词 space-terrestrial integrated network secure relay blockchain Hyperledger Fabric
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Maize-soybean relay cropping increases soybean yield synergistically by extending the post-anthesis leaf stay-green period and accelerating grain filling
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作者 Yiling Li Ping Chen +7 位作者 Zhidan Fu Kai Luo Ping Lin Chao Gao Shanshan Liu Tian Pu Taiwen Yong Wenyu Yang 《The Crop Journal》 SCIE CSCD 2023年第6期1921-1930,共10页
Relay cropping of Poaceae and Fabaceae promotes high yield and land-use efficiency by allowing a double harvest.However,it is difficult to increase yield synergistically because of the reduced photosynthetic abilities... Relay cropping of Poaceae and Fabaceae promotes high yield and land-use efficiency by allowing a double harvest.However,it is difficult to increase yield synergistically because of the reduced photosynthetic abilities of legume leaves under the shade of graminoids.Leaf photosynthetic capacity in relay cropping systems is associated with ecological niche differentiation and photosynthetic compensation after restoration of normal light.We conducted a field experiment in southwest China in 2020–2021 to evaluate the effects of three cropping patterns:maize–soybean relay cropping(IMS),monoculture maize(MM),and monoculture soybean(SS),and N application levels:no N application(NN:0 kg N ha^(−1)),reduced N(RN:180 kg N ha^(−1)),and conventional N(CN:240 kg N ha^(−1)).Compared to monocropping,relay cropping increased the stay-green traits of maize and soybean by 13%and 89%,respectively.Relay cropping prolonged the leaf stay-green duration in the maize and soybean lag phase by almost 4 and 8 days,respectively.Relay cropping maize(IM)increased the leaf area index(LAI)by 79.4%to 88.5%under NN and 55.5%to 148%under RN.Relay cropping soybean(IS)increased the LAI from 115%to 437%at days 40 to 50 after anthesis.IM increased yield by 65.6%.IS increased yield by 9.7%.HI and system yield were at their highest values under RN.In the relay cropping system,reduced N application extended green leaf duration,increased photosynthesis inside the canopy at multiple levels,ultimately increases soybean yield synergistically. 展开更多
关键词 Leaf stay-green Nitrogen reduction Maize-soybean relay cropping Yield
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