In this paper,an energy harvesting enabled cooperative non-orthogonal multiple access(NOMA)system for a multi-cell network is investigated.Particularly,during the direct transmission phase,base stations send their sup...In this paper,an energy harvesting enabled cooperative non-orthogonal multiple access(NOMA)system for a multi-cell network is investigated.Particularly,during the direct transmission phase,base stations send their superposed messages to the near users and far users simultaneously according to a NOMA principle,while the near users act as energy harvesting enabled relays employing a power splitting protocol.During the cooperative phase,the near users transmit their decoded messages to the corresponding far users using harvested energy.Using tools from stochastic geometry,we firstly calculate the signal to interference ratios of the users in each NOMA group including one near user and one far user.Then,the closed-form expressions of the coverage probability,ergodic rate,and energy efficiency are derived respectively.Numerical results validate the derived expressions and show that the energy harvesting enabled cooperative NOMA system in a multi-cell network can improve the coverage probability,ergodic rate,and energy efficiency compared to its counterpart OMA system.展开更多
Agricultural mechanization plays a pivotal role in the transition from subsistence to commercial agriculture, with a particular focus on labour-intensive activities like harvesting. This study assesses the operational...Agricultural mechanization plays a pivotal role in the transition from subsistence to commercial agriculture, with a particular focus on labour-intensive activities like harvesting. This study assesses the operational characteristics of the BRRI Whole Feed Combine Harvester (Model BRRI WCH2021) at the field level. Developed under the SFMRA project, the harvester’s technical performance and loss assessment were conducted during the Boro 2022 and Aman 2022 seasons in farmer fields in Bangladesh’s Rangpur region. The field efficiency of the harvester was determined to be 62.5% and 57.9% in the Boro and Aman seasons, respectively. Fuel consumption rates were recorded at 2.77 l/ha and 2.31 l/ha for the Boro and Aman seasons. The total harvesting losses, encompassing cutter bar, shatter, cylinder, and separation loss, averaged 0.56% and 0.48% in the Boro and Aman seasons, respectively. Mechanized harvesting with the BRRI Whole Feed Combine Harvester significantly reduced paddy losses by 5.81% compared to manual methods. The field evaluation results indicate the combine harvester’s satisfactory performance, highlighting its potential to alleviate labour demands during peak harvesting. The development of the BRRI WCH offers a sustainable solution for rice harvesting mechanization among progressive farmers. It paves the way for the broader adoption of advanced agricultural technology in Bangladesh.展开更多
利用认知无线电非正交多址接入(cognitive radio non-orthogonal multiple access,CR-NOMA)技术可缓解频谱资源短缺问题,提升传感设备的吞吐量。传感设备的能效问题一直制约着传感设备的应用。为此,针对CR-NOMA中的传感设备,提出基于深...利用认知无线电非正交多址接入(cognitive radio non-orthogonal multiple access,CR-NOMA)技术可缓解频谱资源短缺问题,提升传感设备的吞吐量。传感设备的能效问题一直制约着传感设备的应用。为此,针对CR-NOMA中的传感设备,提出基于深度确定策略梯度的能效优化(deep deterministic policy gradientbased energy efficiency optimization,DPEE)算法。DPEE算法通过联合优化传感设备的传输功率和时隙分裂系数,提升传感设备的能效。将能效优化问题建模成马尔可夫决策过程,再利用深度确定策略梯度法求解。最后,通过仿真分析了电路功耗、时隙时长和主设备数对传感能效的影响。仿真结果表明,能效随传感设备电路功耗的增加而下降。此外,相比于基准算法,提出的DPEE算法提升了能效。展开更多
基金supported in part by National Natural Science Foundation of China (61771358)Intergovernmental International Cooperation on Science and Technology Innovation (2016YFE0123200)+2 种基金China Postdoctoral Science Foundation (2017M613074)Fundamental Research Funds for the Central Universities (JB170102)the 111 Project (B08038)
文摘In this paper,an energy harvesting enabled cooperative non-orthogonal multiple access(NOMA)system for a multi-cell network is investigated.Particularly,during the direct transmission phase,base stations send their superposed messages to the near users and far users simultaneously according to a NOMA principle,while the near users act as energy harvesting enabled relays employing a power splitting protocol.During the cooperative phase,the near users transmit their decoded messages to the corresponding far users using harvested energy.Using tools from stochastic geometry,we firstly calculate the signal to interference ratios of the users in each NOMA group including one near user and one far user.Then,the closed-form expressions of the coverage probability,ergodic rate,and energy efficiency are derived respectively.Numerical results validate the derived expressions and show that the energy harvesting enabled cooperative NOMA system in a multi-cell network can improve the coverage probability,ergodic rate,and energy efficiency compared to its counterpart OMA system.
文摘Agricultural mechanization plays a pivotal role in the transition from subsistence to commercial agriculture, with a particular focus on labour-intensive activities like harvesting. This study assesses the operational characteristics of the BRRI Whole Feed Combine Harvester (Model BRRI WCH2021) at the field level. Developed under the SFMRA project, the harvester’s technical performance and loss assessment were conducted during the Boro 2022 and Aman 2022 seasons in farmer fields in Bangladesh’s Rangpur region. The field efficiency of the harvester was determined to be 62.5% and 57.9% in the Boro and Aman seasons, respectively. Fuel consumption rates were recorded at 2.77 l/ha and 2.31 l/ha for the Boro and Aman seasons. The total harvesting losses, encompassing cutter bar, shatter, cylinder, and separation loss, averaged 0.56% and 0.48% in the Boro and Aman seasons, respectively. Mechanized harvesting with the BRRI Whole Feed Combine Harvester significantly reduced paddy losses by 5.81% compared to manual methods. The field evaluation results indicate the combine harvester’s satisfactory performance, highlighting its potential to alleviate labour demands during peak harvesting. The development of the BRRI WCH offers a sustainable solution for rice harvesting mechanization among progressive farmers. It paves the way for the broader adoption of advanced agricultural technology in Bangladesh.
