摘要：Efficient and affordable electrocatalysts for reversible oxygen reduction and oxygen evolution reactions(ORR and OER,respectively)are highly sought-after for use in rechargeable metal-air ***,the construction of high-performance electrocatalysts that possess both largely accessible active sites and superior ORR/OER intrinsic activities is ***,we report the design and successful preparation of a 3D hierarchically porous graphene framework with interconnected interlayer macropores and in-plane mesopores,enriched with pyridinic-nitrogen-cobalt(pyri-N-Co)active sites,namely,CoFe/*** pyri-N-Co bonding significantly accelerates sluggish oxygen electrocatalysis kinetics,in turn substantially improving the intrinsic ORR/OER activities per active site,while copious interlayer macropores and in-plane mesopores enable ultra-efficient mass transfer throughout the graphene architecture,thus ensuring sufficient exposure of accessible pyri-N-Co active sites to the *** a robust catalyst structure endows CoFe/3D-NLG with a remarkably enhanced reversible oxygen electrocatalysis performance,with the ORR half-wave potential identical to that of the benchmark Pt/C catalyst,and OER activity far surpassing that of the noble-metal-based RuO2 ***,when employed as an air electrode for a rechargeable Zn-air battery,CoFe/3D-NLG manifests an exceedingly high open-circuit voltage(1.56 V),high peak power density(213 mW cm^(–2)),ultra-low charge/discharge voltage(0.63 V),and excellent charge/discharge cycling stability,outperforming state-of-the-art noble-metal electrocatalysts.

摘要：The internal flow field of an axial-flow pump under low flow rate conditions is extremely turbulent. The unstable flow region is formed due to the tip leakage and the rotating stall, and is distinguished by a saddle patterned zone in its flow-head curve that demonstrates restrictions in its workable flow range. It is therefore important to understand and improve the operational characteristics of an axial-flow pump under low flow rate conditions. In this study, experiments are performed for the performances of an axial-flow pump at the flow rate in a range between 0.8Qd and 1.2Qd, with the internal flow field measured by the particle image velocimetry (PIV), and with the pump performances and the internal flow field simulated by the Ansys CFX. The simulation results agree well with the experimental results. From the predicted heads at the flow rate in the range between 0.1Qd and 0.7Qd by the numerical simulation, the complete flow-head curves are obtained. The streamlines and the velocity contours in the region in front of the impeller leading edge under different flow conditions are analyzed. By adopting the double-inlet structures, the flow-head characteristics are studied by varying the values of δ and σ respectively, where δ denotes the gap between the inner cylinder end and the impeller leading edge, and σ denotes the gap between the inner cylinder and the outer cylinder. The findings indicate that with the double-inlet design, the velocity distribution can be effectively improved in the region in front of the impeller leading edge, as well as the head performance under the low flow rate conditions, and the positive slope value of the head curve is reduced in the unstable flow range. The optimal δ and σ values are determined.

摘要：针对移动通信网络数据业务急速增长带来的频谱资源紧张和系统能耗增加的问题,超蜂窝网络架构通过控制覆盖和业务覆盖的适度分离,引入基站的动态休眠和资源调度,从而大幅度提高网络的频谱效率和能量效率.但如何在不破坏用户终端协议栈的前提下实现蜂窝网络控制覆盖和业务覆盖的分离,是需要解决的问题.本文分析了GSM系统和LTE系统的主要信令流程及协议架构,提出了相应的超蜂窝网络设计方案,核心思路都是通过逻辑信道的划分实现基站功能的分离,进而实现控制覆盖和业务覆盖的分离.借助软件无线电设备,搭建了超蜂窝网络实验平台,对上述分离方案进行了初步的验证.本文还结合云计算技术和软件定义网络技术,设计了软件定义超蜂窝架构,并搭建了相应的云化超蜂窝网络演示平台.

摘要：Pin and socket contacts are the key parts of electrical connector as aerospace electronic components. The contacts are also the direct carriers for signal transmitting of electronic equipments, passing the signal from the input end to the output end of electrical connector. The reliability of pin and socket contacts directly influences signal transmission. The goal of this study is to enhance the contact reliability of aerospace electrical connector. Computer simulation analysis was made on contacts performance data by utilizing the simulation system developed by PCL Language of MSC software. Furthermore, the results were experi- mentally validated so as to realize the objective of optimizing contacts design.

摘要：作为一种新兴产业,文化创意产业成为我国经济结构调整和经济发展方式转变的重要手段。尤其是自2006年以来,文化创意产业在中国展现出强劲的发展势头,文化创意产业园区如雨后春笋般在各大城市兴起,有关文化创意产业的博览会、设计周、动漫展、高峰论坛等也是层出不穷。这表明中国已经迈开了从"中国制造"走向"中国创造"的伟大脚步。通过分析全球化的特征及其对中国经济的影响来揭示我国文化创意产业发展的必然性和前进方向,针对我国文化创意产业的发展现状总结其发展的创新模式。

摘要：压力容器水位是核电厂设计和运行关注的重点参数之一,本文利用标准不确定度评定方法,结合CPR1000核电厂RPVL测量方法及相关数据,建立了压力容器水位测量不确定度评定模型,为压力容器水位测量不确定度评定提出了具体的方法。为今后核电厂压力容器水位设计和运行,以及进行性能改进提供了理论依据和指导方向。

摘要：文章通过构建"相对技术复杂度"指数,利用UNCTAD"创意经济"数据库发布数据,对我国以及代表性国家创意产品及分项的价值增值能力进行了测算和对比分析。结果显示:我国创意产品整体处于国际分工的低附加值环节,价值增值能力不强;在各创意产品领域中,视觉艺术、设计产品、工艺品和表演艺术的价值增值能力高于其它产品领域,且在世界处于领先地位,而在视听产品、新媒体和出版物三个产品领域,我国的价值增值能力还很低,且近年来改善的迹象不明显。

摘要：5G的大规模部署伴随着网络能耗呈指数级增长,与此同时,国家提出了"碳达峰"与"碳中和"的"双碳"目标,因此移动网络的节能减排已刻不容缓.然而,一方面随着人工智能等技术的发展,未来6G网络中计算类业务预期将迎来大幅增长;另一方面,实现绿色低碳需要提升可再生能源的利用率,但绿色新能源供能不稳难以保证服务质量.为应对以上挑战,本文提出一种能量与信息服务深度融合的低碳网络架构,通过构建一个协调异质资源的智能控制面,充分利用并调度移动网络中泛在的算力、通信和储能,在保证6G个性化业务服务质量要求的同时,以期大幅降低网络能耗与碳排放.本文同时还讨论了该架构下的调度机制设计以及可能的未来研究方向.

摘要：信道信息作为刻画无线信道状态的重要信息,在新一代基于大规模多天线技术的系统中扮演了极其重要的角色.而在超蜂窝架构中,业务基站需要动态休眠以提高系统的能效.当基站休眠时,传统的基于导频的信道信息获取方法无法使用.本文针对这一问题提出了基于机器学习的信道信息获取策略,通过活跃基站多维度的信道信息来推测休眠基站的信道信息.我们以用户选择业务基站为例,利用人工神经网络架构设计了一套具体的信道学习解决方案.与位置辅助信道估计方案不同,该方案采用控制基站侧的信道信息作为输入,避免了用户定位过程中存在的一些问题.通过基于随机地理散射物的信道模型,我们对该方案进行了仿真验证,发现其预测准确率优于K近邻等其他预测算法,性能接近于已知准确用户地理信息的位置辅助估计方案.

摘要：设计了一种针对大规模非光滑优化问题的修正DY共轭梯度算法.新算法的搜索方向不仅自动满足充分下降条件,而且属于信赖域.新算法在适当条件下全局收敛.初步的数值实验显示,新算法能够求解高达50 000维的非光滑凸和非凸优化问题,表明其在求解大规模非光滑无约束凸优化问题方面是有效的.