摘要：相比个体广告支出效率,对一个国家(地区)整体广告支出效率的测量研究更具经济学上的普遍意义。通过对20年来我国每年排名前100位大型广告主相关数据的整合和清洗,可以发现:中国整体广告支出效率呈阶段性上升态势,经历了低效率、效率提升、效率较高三个阶段;中国大型广告主在保持现有销售额的情况下,从整体广告支出效率的理论角度分析可以节约大量广告支出;互联网媒体的广告支出效率高于传统媒体,促进了中国整体广告支出效率的上升。在嵌入性视野下,一些经济和非经济因素对中国整体广告支出效率会产生影响,这些因素包括GDP增长率、广告法律政策体系的建立健全、广告市场主体的专业化程度以及技术进步的速度与空间。对中国整体广告支出效率的研究还需从五个方面进一步推进:一是不同国家体制、不同经济发展水平的整体广告支出效率研究;二是我国不同形态互联网广告的支出效率研究;三是我国不同行业整体广告支出效率差异研究;四是生成式人工智能对中国整体广告支出效率的影响研究;五是中外广告支出效率的比较研究。

摘要：Step-scheme(S-scheme)heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier *** latter is critical in controlling the overall efficiency in one-step photoexcitation *** this study,a nanosized BiVO4/Bi0.6Y0.4VO4 solid solution was prepared by a coprecipitation method following with hydrothermal or calcination *** S-scheme heterojunction was fabricated by in-situ pressure-induced transformations of bismuth vanadate from the tetragonal zircon phase to the monoclinic scheelite phase,which led to the formation of BiVO4 nanoparticles with a diameter of approximately 5 nm on the surface of BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4)/Bi_(0.6)Y_(0.4)VO_(4) with S-scheme heterojunctions showed significantly enhanced photocatalytic overall water splitting activity compared with using bare BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4).Characterization of the carrier dynamics demonstrated that a superior carrier separation through S-type heterojunctions might have caused the enhanced overall water splitting(OWS)*** photovoltage spectra and the results of selective photodeposition experiments indicated that the photogenerated holes mainly migrated to the BiVO4 nanoparticles in the *** confirmed that the charge transfer route corresponds to an S-scheme rather than a type-II heterojunction mechanism under light *** study presents a facile and efficient strategy to construct S-scheme heterojunctions through a pressure-induced phase *** results demonstrated that S-scheme junctions composed of different crystalline phases can boost the carrier separation capacity and eventually improve the photocatalytic OWS activity.

摘要：A two‐step photocatalytic water splitting system,termed a“Z‐scheme system”,was achieved using Zn‐doped g‐C3N4for H2evolution and BiVO4for O2evolution with Fe2+/Fe3+as a shuttle redox mediator.H2and O2were evaluated simultaneously when the doping amount of zinc was10%.Moreover,Zn‐doped(10%)g‐C3N4synthesized by an impregnation method showed superior active ability to form the Z‐scheme with BiVO4than by in‐situ synthesis.X‐ray diffraction,UV‐Vis spectroscopy,scanning electron microscopy,and X‐ray photoelectron spectroscopy were used to characterize the *** was determined that more Zn?N bonds could be formed on the surface of g‐C3N4by impregnation,which could facilitate charge transfer.

摘要：提出一种基于概率存储的启发式住处中心网络内容缓存方法(PCP)。主要思想是请求消息和数据消息在传输过程中统计必要信息,当数据消息返回时,沿途各缓存节点按照一定概率决策是否在本地缓存该内容。设计缓存概率时综合考虑内容热度和缓存放置收益,即内容热度越高,放置收益越大的内容被缓存的概率越高。实验结果表明,PCP在缓存服务率、缓存命中率、平均访问延迟率等方面,与现有方法相比具有显著优势,同时PCP开销较小。

摘要：以往的地下结构抗震研究大多是针对现浇结构开展的,而装配式结构由独立的预制构件拼装而成,从根本上区别于传统整体现浇结构,已有研究得到的认识对其适用性尚不明确,这极大地限制了装配式地下结构在强震区的推广与应用。该文以实际工程为背景,开展了全装配式和同型现浇车站结构的三维非线性有限元时程分析,对比了结构在八度区设防、罕遇和极罕遇地震下的变形、内力和损伤等响应。结果表明:装配式和现浇车站结构整体的地震变形差异不大,但柔性装配式车站结构榫槽节点可产生张开变形。设防和罕遇地震下,节点张开有利于结构减震,装配式车站结构的损伤小于现浇结构;而在极罕遇地震下,节点张开变大,榫槽、榫头和构件边缘的部分区域损伤集中,装配式和现浇结构地震响应产生了较大差异,但因应变幅值有限且损伤范围较小,此时全装配式与现浇车站结构整体的损伤程度基本相当。

摘要：Valves are widely used in various working conditions for their flow control functions,and the cavitation inside valves has been investigated owing to its harm to the valve itself and the connecting downstream *** paper presents a comprehensive review of the progress that has been achieved in the past years about cavitation in valves including both mechanical heart valves and control *** review is divided in the following parts,namely the location where there is a high possibility of the occurrence of cavitation,the parameters that affect cavitation intensity,and the methods to minimize cavitation *** should be noticed that although simulation has been widely used,advanced experiments are still needed in order to obtain accurate analysis of cavitation in valves and the cavitation model still needs to be improved.

摘要：人工智能技术的应用颠覆了传统广告运作,形成了消费者智能洞察、广告智能创作、广告智能投放和广告智能评估的新流程。在新流程中,广告评估环节智能化运用的理论研究相对滞后。以广告运作流程中的效果评估环节为研究对象,以共振效应理论为分析框架,探索了智能技术在广告评估环节中的具体运用,提炼出广告智能评估的识别、分析与应对模型,总结了广告智能评估的共振效应,为业界广告评估环节的智能化转型提供了理论指导。

摘要：A design and optimization approach of dynamic and control performance for a two-DOF planar manipulator was *** the kinematic and dynamic analysis,several advantages of the mechanism were illustrated,which made it possible to obtain good dynamic and control performances just through mechanism *** on the idea of design for control(DFC),a novel kind of multi-objective optimization model was *** were three optimization objectives:the index of inertia,the index describing the dynamic coupling effects and the global condition *** indexes to characterize the designing requirements such as the velocity of end-effector,the workspace size,and the first mode natural frequency were regarded as the *** cross-section area and length of the linkages were chosen as the design ***-II algorithm was introduced to solve this complex multi-objective optimization *** criteria from engineering experience were incorporated into the selecting of final parameters among the obtained Pareto solution ***,experiments were performed to validate the linear dynamic structure and control performances of the optimized mechanisms.A new expression for measuring the dynamic coupling degree with clear physical meaning was *** results show that the optimized mechanism has an approximate decoupled dynamics structure,and each active joint can be regarded as a linear SISO *** control performances of the linear and nonlinear controllers were also *** can be concluded that the optimized mechanism can achieve good control performance only using a linear controller.

摘要：目的:套筒式调节阀内空化的发生不仅会增加整个管路系统的能量损耗,而且会造成阀体及管路的失效破坏。本文旨在探讨四种不同形状的阀芯对套筒式调节阀内不同阀芯位移工况下的空化流动及空化强度的影响,为套筒式调节阀的优化设计及空化控制提出建议。创新点:1.根据四种不同形状的阀芯,研究套筒式调节阀内阀芯形状对流动及空化特性的影响;2.建立数值模型,对套筒式调节阀在不同阀芯形状和不同阀芯位移条件下进行流动及空化分析。方法:1.建立带有不同形状阀芯的套筒式调节阀数值计算模型,并比较分析阀芯形状对阀内速度、压力及空化情况的影响(图4,8和11);2.建立不同阀芯位移条件下的阀门数值模型,比较分析阀芯位移对阀内速度、压力及空化情况的影响(图6和10);3.建立不同形状阀芯及不同阀芯位移下的阀门模型,分析阀芯形状和位移对阀内流动及空化特性的综合影响(图7和13)。结论:1.在四种不同形状阀芯的条件下,高速流动区域和空化发生区主要位于套筒与阀芯之间的间隙;2.在直筒形和椭球形阀芯条件下的阀内空化强度明显强于平底形和圆台形阀芯条件下的空化强度,因此平底形和圆台形阀芯在空化控制方面具有更好的效果;3.在四种不同形状阀芯的条件下,随着阀芯位移的增加,阀内由空化产生的蒸汽总体积先增加后减少。

摘要：Based on LMDZ4 daily temperature dataset,equidistant cumulative distribution function matching method(EDCDFm)and cumulative distribution function-transform method(CDF-t)are used to evaluate the ability of models in simulating extreme temperature over central and eastern *** future temperature change is then *** results show that the EDCDFm and CDF-t methods function effectively correct the spatial distribution of daily mean temperature and extreme temperature,significantly reduce the biases of the model simulation and effectively improve the capacity of models for spatial pattern of extreme ***,the cold bias of the CDF-t method in winter is obviously higher than that of the EDCDFm method,and the temperature change curve of the EDCDFm method is closer to the observation than that of the CDF-t *** projection based on the EDCDFm method shows that under the RCP4.5 emission scenario,the temperature in the study area shows a warming *** to 1986e2005,the mean temperature is projected to increase by 0.76,1.84,and 2.10℃during 2017e2036,2046e2065,and 2080e2099,*** spatial change for the mean,maximum,and minimum temperature in the three future periods have good consistency;warming in northern China is higher than that in the *** in temperature projection are large in the Tibetan Plateau and Sichuan *** days decrease significantly,especially in the Tibetan Plateau,and the frost days in the three periods decrease by more than 15,30,and 40 d,*** variation of heat wave indice is the smallest;the increase of heat wave is mainly in eastern China,and the increase in South China is more than 2 ***,under the global warming of 1.5℃and 2℃,the response characteristics of extreme temperature over central and eastern China are also *** results show that the mean temperature,maximum temperature and minimum temperature in the study area increase by more than 0.75℃under 1.5℃target