针对低轨卫星高动态场景下多服务质量(Quality of Service,QoS)时变物联业务资源调度问题,提出了一种基于Lyapunov优化的窄带物联网(Narrow Band Internet of Things,NB-IoT)多业务资源切片动态管理方法。该方法综合考虑多物联业务QoS...针对低轨卫星高动态场景下多服务质量(Quality of Service,QoS)时变物联业务资源调度问题,提出了一种基于Lyapunov优化的窄带物联网(Narrow Band Internet of Things,NB-IoT)多业务资源切片动态管理方法。该方法综合考虑多物联业务QoS需求、不同QoS业务队列状态以及切片大小的动态划分,构建了资源切片动态管理的资源调度优化问题。基于Lyapunov优化理论将非凸的多时隙动态资源切片划分问题转化为单时隙多QoS业务资源切片配置问题,从而在动态业务场景下实现资源切片与多QoS业务队列之间的动态适配。仿真结果表明,与传统NB-IoT上行资源调度方法相比,所提方法在低轨高动态场景下能够显著提升时延确定性业务的QoS保障和吞吐量。展开更多
High-entropy alloys,a novel class of materials characterized by the statistical distribution of multiple principal elements on simple crystalline lattices,have emerged as a research hotspot in materials science and co...High-entropy alloys,a novel class of materials characterized by the statistical distribution of multiple principal elements on simple crystalline lattices,have emerged as a research hotspot in materials science and condensed matter physics due to their exceptional mechanical properties and unique high-entropy characteristic.Since the discovery of the first high-entropy superconductor in 2014,exploring their superconducting performance and advantages has progressively become a frontier in scientific research.The Ta-Nb-Hf-Zr-Ti system,in particular,exhibits remarkable mechanical robustness,outstanding radiation tolerance,and superconducting performance comparable to the binary NbTi alloy,positioning it as a promising candidate for advanced applications,such as high-field superconducting magnets,superconducting electric motors,and next-generation nuclear fusion reactors.This review systematically summarized global research progress on Ta-Nb-Hf-Zr-Ti-based superconductors,aiming to provide a comprehensive reference for advancing this burgeoning field.展开更多
针对电力物联网环境下配电变压器状态监测面临的低功耗、可靠传输及数据融合等技术难题,设计基于窄带物联网(Narrow Band Internet of Things,NB-IoT)的配电变压器状态监测系统。该系统采用省电模式(Power Saving Mode,PSM)休眠控制策...针对电力物联网环境下配电变压器状态监测面临的低功耗、可靠传输及数据融合等技术难题,设计基于窄带物联网(Narrow Band Internet of Things,NB-IoT)的配电变压器状态监测系统。该系统采用省电模式(Power Saving Mode,PSM)休眠控制策略降低终端能耗,利用受限应用协议(Constrained Application Protocol,CoAP)及重传机制保障数据可靠传输,并引入加权融合计算实现多源异构数据的协同诊断。研究结果表明,该系统能够有效满足配电变压器长期稳定运行与精准状态评估的需求。展开更多
针对智慧电厂汽轮机振动监测中的强电磁干扰、部署困难及带宽瓶颈等挑战,提出了相应的窄带物联网(Narrow Band-Internet of Things,NB-IoT)通信技术应用方案。该方案采用授权频段规避干扰,部署无线终端简化布线,利用独立子载波优化数据...针对智慧电厂汽轮机振动监测中的强电磁干扰、部署困难及带宽瓶颈等挑战,提出了相应的窄带物联网(Narrow Band-Internet of Things,NB-IoT)通信技术应用方案。该方案采用授权频段规避干扰,部署无线终端简化布线,利用独立子载波优化数据汇聚,构建了稳定高效的监测体系。应用案例分析表明,NB-IoT通信技术能显著提升振动数据传输的可靠性与实时性。展开更多
针对智慧仓储场景中多径/非视距无线传输(Non Line of Sight,NLOS)无线传输干扰导致定位精度低、终端续航短、部署成本高三大瓶颈,提出窄带物联网(Narrow Band Internet of Things,NB-IoT)与超宽带(Ultra Wide Band,UWB)融合的定位算法...针对智慧仓储场景中多径/非视距无线传输(Non Line of Sight,NLOS)无线传输干扰导致定位精度低、终端续航短、部署成本高三大瓶颈,提出窄带物联网(Narrow Band Internet of Things,NB-IoT)与超宽带(Ultra Wide Band,UWB)融合的定位算法改进方案。首先,构建时延-能量联合约束的加权最小二乘(Weighted Least Squares,WLS)与扩展卡尔曼滤波(Extended Kalman Filter,EKF)联合模型,引入信道状态信息(Channel State Information,CSI)能量熵权重与动态遮挡因子抑制干扰,提升复杂环境下的定位稳定性;其次,设计加权信号质量评估+自适应同步周期的动态功耗管理策略,有效减少模式切换振荡与无效能耗;最后,搭建射频(Radio Frequency,RF)+压电+光伏多源能量回收架构,结合动态电压调整(Dynamic Voltage Scaling,DVS)优化功率分配,延长终端续航。仿真验证结果表明:在金属货架区、NLOS货物堆放区、自动导向车(Automated Guided Vehicle,AGV)动态通道区,改进方案(粒子滤波优化版)的平均定位误差分别降至0.30、0.40、0.28 m,较传统UWB-飞行时间(Time Of Flight,TOF)方案降低75%~81%;终端平均功耗降低42%,启用多源能量回收架构后续航延长至60个月;以100 000 m2仓储场景测算,部署成本较NB-IoT+UWB基础融合方案降低30%。该方案适配常规及冷链、化工等极端仓储场景,为智慧仓储定位的工程化落地提供了技术支撑。展开更多
高压电缆接头局部放电监测是电力系统状态检修的重要基础。分析窄带物联网(Narrow Band Internet of Things,NB-IoT)技术的特点,设计基于NB-IoT的高压电缆接头局部放电远程监测系统,围绕放电信号获取、终端节点构建、数据远程传输与运...高压电缆接头局部放电监测是电力系统状态检修的重要基础。分析窄带物联网(Narrow Band Internet of Things,NB-IoT)技术的特点,设计基于NB-IoT的高压电缆接头局部放电远程监测系统,围绕放电信号获取、终端节点构建、数据远程传输与运行状态监控形成完整实现方案,并结合系统性能测试验证其在放电识别、数据上报与运行时长方面的工程适用性,为高压电缆接头在线监测与运维管理提供技术支撑。展开更多
为提高铁路供配电系统故障检测的及时性和精准性,基于窄带物联网(Narrow Band Internet of Things,NB-IoT)通信技术,提出了铁路供配电系统故障数据识别技术,并构建了完整的数据采集、传输和识别模型系统。研究结果表明,该技术在故障识...为提高铁路供配电系统故障检测的及时性和精准性,基于窄带物联网(Narrow Band Internet of Things,NB-IoT)通信技术,提出了铁路供配电系统故障数据识别技术,并构建了完整的数据采集、传输和识别模型系统。研究结果表明,该技术在故障识别准确性和响应速度上表现突出,为复杂环境下铁路供配电系统的稳定运行提供了有效支持。展开更多
针对台区智能融合终端通信现存接入冲突、传输效率低、资源利用不均及能耗过高问题,提出基于窄带物联网(Narrow Band-Internet of Things,NB-IoT)的通信优化方案。该方案包括台区终端分级接入控制、上行数据报文聚合、空口资源动态调度...针对台区智能融合终端通信现存接入冲突、传输效率低、资源利用不均及能耗过高问题,提出基于窄带物联网(Narrow Band-Internet of Things,NB-IoT)的通信优化方案。该方案包括台区终端分级接入控制、上行数据报文聚合、空口资源动态调度及终端能耗自适应调控等设计。开展实验验证方案有效性,实验结果表明,该优化方案可显著提升台区终端通信性能,为台区智能融合终端通信优化提供可靠的技术支撑。展开更多
The elimination of the B2 phase in aβ-solidifying high Nb-containing TiAl alloy withβ/B2 andγphases was investigated using different heat treatments,with a focus on understanding the phase transformations and lamel...The elimination of the B2 phase in aβ-solidifying high Nb-containing TiAl alloy withβ/B2 andγphases was investigated using different heat treatments,with a focus on understanding the phase transformations and lamellae formation during the process.The phase transformation and lamellae formation during B2 phase elimination differs from that observed in conventional TiAl alloys.During the holding stage of heat treatment,theβ/B2 phase is replaced by theαphase through primary phase transformations ofβ→αandγ→α.Lamellae formation occurs within bothαandγgrains during cooling,initiating 30-40℃below the annealing temperature.This lamellar structure was formed via two main mechanisms:nucleation at grain boundaries followed by growth into the grain,and direct precipitation and growth within the grain.The orientation relationship between theγphase and its adjacentαphase is(111)_(γ)//(0001)_(α)and[011]_(γ)//[1120]_(α),with a coherency between the phases characterized by a misfit of approximately 1.7%.展开更多
文摘针对低轨卫星高动态场景下多服务质量(Quality of Service,QoS)时变物联业务资源调度问题,提出了一种基于Lyapunov优化的窄带物联网(Narrow Band Internet of Things,NB-IoT)多业务资源切片动态管理方法。该方法综合考虑多物联业务QoS需求、不同QoS业务队列状态以及切片大小的动态划分,构建了资源切片动态管理的资源调度优化问题。基于Lyapunov优化理论将非凸的多时隙动态资源切片划分问题转化为单时隙多QoS业务资源切片配置问题,从而在动态业务场景下实现资源切片与多QoS业务队列之间的动态适配。仿真结果表明,与传统NB-IoT上行资源调度方法相比,所提方法在低轨高动态场景下能够显著提升时延确定性业务的QoS保障和吞吐量。
基金Northwest Institute of Nonferrous Metal Research Funding(YK2324)Key Research and Development Program of Shaanxi(2024GX-YBXM-403)National Natural Science Foundation of China(52277029)。
文摘High-entropy alloys,a novel class of materials characterized by the statistical distribution of multiple principal elements on simple crystalline lattices,have emerged as a research hotspot in materials science and condensed matter physics due to their exceptional mechanical properties and unique high-entropy characteristic.Since the discovery of the first high-entropy superconductor in 2014,exploring their superconducting performance and advantages has progressively become a frontier in scientific research.The Ta-Nb-Hf-Zr-Ti system,in particular,exhibits remarkable mechanical robustness,outstanding radiation tolerance,and superconducting performance comparable to the binary NbTi alloy,positioning it as a promising candidate for advanced applications,such as high-field superconducting magnets,superconducting electric motors,and next-generation nuclear fusion reactors.This review systematically summarized global research progress on Ta-Nb-Hf-Zr-Ti-based superconductors,aiming to provide a comprehensive reference for advancing this burgeoning field.
文摘针对电力物联网环境下配电变压器状态监测面临的低功耗、可靠传输及数据融合等技术难题,设计基于窄带物联网(Narrow Band Internet of Things,NB-IoT)的配电变压器状态监测系统。该系统采用省电模式(Power Saving Mode,PSM)休眠控制策略降低终端能耗,利用受限应用协议(Constrained Application Protocol,CoAP)及重传机制保障数据可靠传输,并引入加权融合计算实现多源异构数据的协同诊断。研究结果表明,该系统能够有效满足配电变压器长期稳定运行与精准状态评估的需求。
文摘针对智慧电厂汽轮机振动监测中的强电磁干扰、部署困难及带宽瓶颈等挑战,提出了相应的窄带物联网(Narrow Band-Internet of Things,NB-IoT)通信技术应用方案。该方案采用授权频段规避干扰,部署无线终端简化布线,利用独立子载波优化数据汇聚,构建了稳定高效的监测体系。应用案例分析表明,NB-IoT通信技术能显著提升振动数据传输的可靠性与实时性。
文摘针对智慧仓储场景中多径/非视距无线传输(Non Line of Sight,NLOS)无线传输干扰导致定位精度低、终端续航短、部署成本高三大瓶颈,提出窄带物联网(Narrow Band Internet of Things,NB-IoT)与超宽带(Ultra Wide Band,UWB)融合的定位算法改进方案。首先,构建时延-能量联合约束的加权最小二乘(Weighted Least Squares,WLS)与扩展卡尔曼滤波(Extended Kalman Filter,EKF)联合模型,引入信道状态信息(Channel State Information,CSI)能量熵权重与动态遮挡因子抑制干扰,提升复杂环境下的定位稳定性;其次,设计加权信号质量评估+自适应同步周期的动态功耗管理策略,有效减少模式切换振荡与无效能耗;最后,搭建射频(Radio Frequency,RF)+压电+光伏多源能量回收架构,结合动态电压调整(Dynamic Voltage Scaling,DVS)优化功率分配,延长终端续航。仿真验证结果表明:在金属货架区、NLOS货物堆放区、自动导向车(Automated Guided Vehicle,AGV)动态通道区,改进方案(粒子滤波优化版)的平均定位误差分别降至0.30、0.40、0.28 m,较传统UWB-飞行时间(Time Of Flight,TOF)方案降低75%~81%;终端平均功耗降低42%,启用多源能量回收架构后续航延长至60个月;以100 000 m2仓储场景测算,部署成本较NB-IoT+UWB基础融合方案降低30%。该方案适配常规及冷链、化工等极端仓储场景,为智慧仓储定位的工程化落地提供了技术支撑。
文摘高压电缆接头局部放电监测是电力系统状态检修的重要基础。分析窄带物联网(Narrow Band Internet of Things,NB-IoT)技术的特点,设计基于NB-IoT的高压电缆接头局部放电远程监测系统,围绕放电信号获取、终端节点构建、数据远程传输与运行状态监控形成完整实现方案,并结合系统性能测试验证其在放电识别、数据上报与运行时长方面的工程适用性,为高压电缆接头在线监测与运维管理提供技术支撑。
文摘为提高铁路供配电系统故障检测的及时性和精准性,基于窄带物联网(Narrow Band Internet of Things,NB-IoT)通信技术,提出了铁路供配电系统故障数据识别技术,并构建了完整的数据采集、传输和识别模型系统。研究结果表明,该技术在故障识别准确性和响应速度上表现突出,为复杂环境下铁路供配电系统的稳定运行提供了有效支持。
文摘针对台区智能融合终端通信现存接入冲突、传输效率低、资源利用不均及能耗过高问题,提出基于窄带物联网(Narrow Band-Internet of Things,NB-IoT)的通信优化方案。该方案包括台区终端分级接入控制、上行数据报文聚合、空口资源动态调度及终端能耗自适应调控等设计。开展实验验证方案有效性,实验结果表明,该优化方案可显著提升台区终端通信性能,为台区智能融合终端通信优化提供可靠的技术支撑。
基金supported by the National Natural Science Foundation of China(Nos.51871012,52071021)Beijing Natural Science Foundation,China(No.2162024)+1 种基金Fundamental Research Funds for the Central Universities,China(No.FRF-GF-20-20B)the National Program on Key Basic Research Project of China(No.2011CB605502)。
文摘The elimination of the B2 phase in aβ-solidifying high Nb-containing TiAl alloy withβ/B2 andγphases was investigated using different heat treatments,with a focus on understanding the phase transformations and lamellae formation during the process.The phase transformation and lamellae formation during B2 phase elimination differs from that observed in conventional TiAl alloys.During the holding stage of heat treatment,theβ/B2 phase is replaced by theαphase through primary phase transformations ofβ→αandγ→α.Lamellae formation occurs within bothαandγgrains during cooling,initiating 30-40℃below the annealing temperature.This lamellar structure was formed via two main mechanisms:nucleation at grain boundaries followed by growth into the grain,and direct precipitation and growth within the grain.The orientation relationship between theγphase and its adjacentαphase is(111)_(γ)//(0001)_(α)and[011]_(γ)//[1120]_(α),with a coherency between the phases characterized by a misfit of approximately 1.7%.
