针对现有工作仅考虑理想信道状态信息(Channel State Information,CSI)与硬件调控能力导致在实际系统中用户传输中断过高的问题,该文综合考虑不完美CSI、有限相移调控、硬件损伤的影响,提出了一种基于智能反射面(Intelligent Reflecting...针对现有工作仅考虑理想信道状态信息(Channel State Information,CSI)与硬件调控能力导致在实际系统中用户传输中断过高的问题,该文综合考虑不完美CSI、有限相移调控、硬件损伤的影响,提出了一种基于智能反射面(Intelligent Reflecting Surface,IRS)辅助的鲁棒能效优化算法.考虑基站最大发射功率与IRS离散相移约束及差异化用户传输速率需求,基于高斯CSI误差模型和加性硬件损伤模型,将基站主动波束成形与IRS被动相移优化问题建模为含不确定性参数的多变量耦合能效最大化问题.考虑波束向量与相移矩阵的耦合性,利用交替优化策略将原问题转化为主动波束子问题和离散相移子问题.利用伯恩斯坦不等式、丁克尔巴赫方法及连续凸近似将波束子问题转化为凸优化问题求解;基于求解的主动波束向量,利用罚函数法和投影定理求解离散相移子问题.仿真结果表明,与传统非鲁棒算法相比,所提算法能效性能提升15.8%,平均中断概率间隙达86.7%.展开更多
Time synchronization is a critical middleware service of wireless sensor networks. Researchers have already proposed some time synchronization algorithms. However, due to the demands for various synchronization precis...Time synchronization is a critical middleware service of wireless sensor networks. Researchers have already proposed some time synchronization algorithms. However, due to the demands for various synchronization precision, existing time synchronization algorithms often need to be adapted. So it is necessary to evaluate these adapted algorithms before use. Software simulation is a valid and quick way to do it. In this paper, we present a time synchronization simulator, Simsync, for wireless sensor networks. We decompose the packet delay into 6 delay components and model them separately. The frequency of crystal oscillator is modeled as Gaussian. To testify its effectiveness, we simulate the reference broadcast synchronization algorithm (RBS) and the timing-sync synchronization algorithm (TPSN) on Simsync. Simulated results are also presented and analyzed.展开更多
Wireless sensor networks have already enabled numerous embedded wireless applications such as military, environmental monitoring, intelligent building, etc. Because micro-sensor nodes are supposed to operate for month...Wireless sensor networks have already enabled numerous embedded wireless applications such as military, environmental monitoring, intelligent building, etc. Because micro-sensor nodes are supposed to operate for months or even years with very limited battery power source, it is a challenge for researchers to obtain long operating hour without scarifying original system performances. In this paper, the energy consumption sources of the wireless sensor networks are firstly analyzed, with the digital processing and radio transceiver units being emphasized. Then, we introduce the design scheme of our energy-aware wireless sensor network (GAINS). In GAINS, techniques to conserve the energy are exploited including the energy optimization node, software and energy-efficient communication protocol. The design architecture of our ultra low power wireless sensor network (WO-LPP) is specially presented.展开更多
The evolution of void nucleation inα-A12O3 irradiated by En ≥ 1 MeV neutrons of 3× 1020 cm-2 and post-annealed from 100°C to 1050°C is studied by a positron annihilation lifetime technique. The void n...The evolution of void nucleation inα-A12O3 irradiated by En ≥ 1 MeV neutrons of 3× 1020 cm-2 and post-annealed from 100°C to 1050°C is studied by a positron annihilation lifetime technique. The void nucleation starts at 500℃. The radius of created voids is 0.31 urn and the number of voids increases with increasing annealing temperature from 550℃ to 750℃. Afterwards, the radius of voids increases rapidly and reaches 1.21nm at 1050℃.展开更多
The g-factors of the rotational states along the positive parity yrast band in even-even nuclei ^(84)Zr were measured up to a spin I=16^(+)by a transient magnetic field-ion implanted perturbed angular distribution met...The g-factors of the rotational states along the positive parity yrast band in even-even nuclei ^(84)Zr were measured up to a spin I=16^(+)by a transient magnetic field-ion implanted perturbed angular distribution method and calculated by a cranking shell model.A peak structure of the g-factors has been observed for the first time.The measured g-factors confirm the mixed configuration of proton and neutron alignments.展开更多
The void evolution inα-Al2O3 irradiated by En≥1 MeV neutrons of 3×10^(20)cm^(-2) and post-annealed from 100°C to 1050°C has been studied by a positron annihilation lifetime technique.The void nucleati...The void evolution inα-Al2O3 irradiated by En≥1 MeV neutrons of 3×10^(20)cm^(-2) and post-annealed from 100°C to 1050°C has been studied by a positron annihilation lifetime technique.The void nucleation starts at 500°C.In the annealing temperature region from 550℃ to 750℃,the radius of created voids keeps constant at a value of about 0.29 nm and the number of voids increases with increasing temperature.Afterwards,the radius of voids increases rapidly with the increasing annealing temperature and reaches 1.21nm at 1050℃.展开更多
文摘针对现有工作仅考虑理想信道状态信息(Channel State Information,CSI)与硬件调控能力导致在实际系统中用户传输中断过高的问题,该文综合考虑不完美CSI、有限相移调控、硬件损伤的影响,提出了一种基于智能反射面(Intelligent Reflecting Surface,IRS)辅助的鲁棒能效优化算法.考虑基站最大发射功率与IRS离散相移约束及差异化用户传输速率需求,基于高斯CSI误差模型和加性硬件损伤模型,将基站主动波束成形与IRS被动相移优化问题建模为含不确定性参数的多变量耦合能效最大化问题.考虑波束向量与相移矩阵的耦合性,利用交替优化策略将原问题转化为主动波束子问题和离散相移子问题.利用伯恩斯坦不等式、丁克尔巴赫方法及连续凸近似将波束子问题转化为凸优化问题求解;基于求解的主动波束向量,利用罚函数法和投影定理求解离散相移子问题.仿真结果表明,与传统非鲁棒算法相比,所提算法能效性能提升15.8%,平均中断概率间隙达86.7%.
基金Supported in part by National Basic Research Program of P. R. China(2005CB321604) in part by National Natural Science Foundation of P. R. China (90207002)
文摘Time synchronization is a critical middleware service of wireless sensor networks. Researchers have already proposed some time synchronization algorithms. However, due to the demands for various synchronization precision, existing time synchronization algorithms often need to be adapted. So it is necessary to evaluate these adapted algorithms before use. Software simulation is a valid and quick way to do it. In this paper, we present a time synchronization simulator, Simsync, for wireless sensor networks. We decompose the packet delay into 6 delay components and model them separately. The frequency of crystal oscillator is modeled as Gaussian. To testify its effectiveness, we simulate the reference broadcast synchronization algorithm (RBS) and the timing-sync synchronization algorithm (TPSN) on Simsync. Simulated results are also presented and analyzed.
基金Supported in part by National Basic Research Program of P. R. China (2005CB321604) in part by National Natural Science Foundation of P. R. China (90207002)
文摘Wireless sensor networks have already enabled numerous embedded wireless applications such as military, environmental monitoring, intelligent building, etc. Because micro-sensor nodes are supposed to operate for months or even years with very limited battery power source, it is a challenge for researchers to obtain long operating hour without scarifying original system performances. In this paper, the energy consumption sources of the wireless sensor networks are firstly analyzed, with the digital processing and radio transceiver units being emphasized. Then, we introduce the design scheme of our energy-aware wireless sensor network (GAINS). In GAINS, techniques to conserve the energy are exploited including the energy optimization node, software and energy-efficient communication protocol. The design architecture of our ultra low power wireless sensor network (WO-LPP) is specially presented.
基金the National Natural Science Foundation (No.19835050) and Nuclear industryScience Foundation (No.H7196BOll6)
文摘The evolution of void nucleation inα-A12O3 irradiated by En ≥ 1 MeV neutrons of 3× 1020 cm-2 and post-annealed from 100°C to 1050°C is studied by a positron annihilation lifetime technique. The void nucleation starts at 500℃. The radius of created voids is 0.31 urn and the number of voids increases with increasing annealing temperature from 550℃ to 750℃. Afterwards, the radius of voids increases rapidly and reaches 1.21nm at 1050℃.
基金Supported by the National Natural Science Foundation of China under Grant No.19775070.
文摘The g-factors of the rotational states along the positive parity yrast band in even-even nuclei ^(84)Zr were measured up to a spin I=16^(+)by a transient magnetic field-ion implanted perturbed angular distribution method and calculated by a cranking shell model.A peak structure of the g-factors has been observed for the first time.The measured g-factors confirm the mixed configuration of proton and neutron alignments.
基金Supported in par t by the National Natural Science Foundation of China under Grant No.19835050the Nuclear Indus try Science Foundation of China under Grant No.H7196BO116the Contract of 97J11.2.8HZ010.
文摘The void evolution inα-Al2O3 irradiated by En≥1 MeV neutrons of 3×10^(20)cm^(-2) and post-annealed from 100°C to 1050°C has been studied by a positron annihilation lifetime technique.The void nucleation starts at 500°C.In the annealing temperature region from 550℃ to 750℃,the radius of created voids keeps constant at a value of about 0.29 nm and the number of voids increases with increasing temperature.Afterwards,the radius of voids increases rapidly with the increasing annealing temperature and reaches 1.21nm at 1050℃.
