Experimental Study of Local Scour Around Four Piles Under Different Attack Angles and Gap Ratios

In an effort to investigate and quantify the patterns of local scour,researchers embarked on an in-depth study using a systematic experimental approach.The research focused on the effects of local scour around a set of four piles,each subjected to different hydromechanical conditions.In particular,this study aimed to determine how different attack angles—the angles at which the water flow impinges on the piles,and gap ratios—the ratios of the spacing between the piles to their diameters,influence the extent and nature of scour.A comprehensive series of 35 carefully designed experiments were orchestrated,each designed to dissect the nuances in how the gap ratio and attack angle might contribute to changes in the local scour observed at the base of pile groups.During these experimental trials,a wealth of local scour data were collected to support the analysis.These data included precise topographic profiles of the sediment bed around the pile groups,as well as detailed scour time histories showing the evolution of scour at strategic feature points throughout the test procedure.The analysis of the experimental data provided interesting insights.The study revealed that the interplay between the gap ratio and the attack angle had a pronounced influence on the scouring dynamics of the pile groups.One of the key observations was that the initial phases of scour,particularly within the first hour of water flow exposure,were characterized by a sharp increase in the scour depth occurring immediately in front of the piles.After this initial rapid development,the scour depth transitioned to a more gradual change rate.In contrast,the scour topography around the piles continuously evolved.This suggests that sediment displacement and the associated sculpting of the seabed around pile foundations are sustained and progressive processes,altering the underwater landscape over time.The results of this empirical investigation have significant implications for the design and construction of offshore multi-pile foundations,providing a critical reference for engineers and designers to estimate the expected scour depth around such structures,which is an integral part of decisions regarding foundation design,selection of structural materials,and implementation of scour protection measures.

Optimal design for rubber concrete layered periodic foundations based on the analytical approximations of band gaps and mapping relations

The seismic performance of rubber concrete-layered periodic foundations are significantly influenced by their design,in which the band gaps play a paramount role.Aiming at providing better designs for these foundations,this study first proposes and validates the analytical formulas to approximate the bounds of the first few band gaps.In addition,the mapping relations linking the frequencies of different band gaps are presented.Furthermore,an optimal design method for these foundations is developed,which is validated through an engineering example.It is demonstrated that ensuring the superstructure’s resonance zones are completely covered by the corresponding periodic foundation’s band gaps can achieve satisfactory vibration attenuation effects,which is a good strategy for the design of rubber concrete layered periodic foundations.

International Standardization of Blockchain and Distributed Ledger Technology:Overlaps,Gaps and Challenges

As one of the most concerned digital technologies in recent years,blockchain and distributed ledger technology are an important driving force for a new round of technological development.It is currently in the process of accelerating its evolution and maturity,and has gradually integrated with other digital technologies.It has been applied in many industries,providing decentralized solutions for various industries,realizing innovative storage models,and building a new trust system.As blockchain technology is officially incorporated into China’s new information infrastructure category,the application fields of blockchain have expanded rapidly,gradually extending from the financial field and government affairs to other fields in the real economy.At the same time,with the continuous development of the globalized economy,blockchain technology will also have a profound impact on international technological and economic development.Therefore,for the healthy and orderly development and real implementation of the blockchain industry,standardize the application of blockchain,effectively break through the cognitive and technical barriers between different countries,industries and systems on a global scale,prevent application risks,the development of the global blockchain industry needs standardization basis,which is particularly important and urgent.A sound standard system is an important key to the successful development of technology,and formulating the right standard at the right time for technology development helps ensure the ease of use and interoperability of the technology.From the perspective of international standardization,this article first introduces the general situation of ISO,ITU-T,IEEE,W3C and other international standardization organizations,and sorts out the status quo of the blockchain standardization working groups of mainstream international standardization organizations.All blockchain-related standards under development have been analyzed for the characteristics of international blockchain technology standards and industry application standards.Through data analysis,the overlaps,differences and conflicts in the field of international blockchain standard formulation are sorted out,and suggestions for blockchain standardization work in the application and development of blockchain technology standardization by international organizations and industries are put forward.The plans and layouts of future international standards are summarized to help the development of the international standardization of blockchain.

Electrochemical Water Splitting:Bridging the Gaps Between Fundamental Research and Industrial Applications

Electrochemical water splitting represents one of the most promising technologies to produce green hydrogen,which can help to realize the goal of achieving carbon neutrality.While substantial efforts on a laboratory scale have been made for understanding fundamental catalysis and developing high-performance electrocatalysts for the two half-reactions involved in water electrocatalysis,much less attention has been paid to doing relevant research on a larger scale.For example,few such researches have been done on an industrial scale.Herein,we review the very recent endeavors to bridge the gaps between fundamental research and industrial applications for water electrolysis.We begin by introducing the fundamentals of electrochemical water splitting and then present comparisons of testing protocol,figure of merit,catalyst of interest,and manufacturing cost for laboratory and industry-based water-electrolysis research.Special attention is paid to tracking the surface reconstruction process and identifying real catalytic species under different testing conditions,which highlight the significant distinctions of corresponding electrochemical reconstruction mechanisms.Advances in catalyst designs for industry-relevant water electrolysis are also summarized,which reveal the progress of moving the practical applications forward and accelerating synergies between material science and engineering.Perspectives and challenges of electrocatalyst design strategies are proposed finally to further bridge the gaps between lab-scale research and large-scale electrocatalysis applications.

Income Growth,Income Gaps,and Rural Poverty Reduction in China

This paper analyzes the evolving trends in China’s rural poverty from 1988 to 2018 and how income growth and income gaps contributed to poverty reduction using rural household data from the China Household Income Project(CHIP).We find that after China’s reform and opening up policy introduced in 1978,China’s rural poverty has been reduced substantially due primarily to income growth,although this poverty-reducing effect was partially offset by widening income gaps.During the progress of this poverty reduction,however,income distribution replaced income growth as the key driver.For the extremely poor in particular,their poverty status hinged upon income distribution.As revealed by our empirical analysis of income sources,wage income became the chief source of income for rural households,contributing a rising share to poverty reduction in the countryside.The contribution of net income from government transfer to poverty reduction has increased in recent years,and this contribution has been increased with the deepening level of poverty.Calculation of the pro-poor growth index suggests that the poor population primarily benefited from the trickle-down effect of economic growth,and the economic growth pattern has yet to lean towards pro-poor growth.

氢氟酸处理InP/GaP/ZnS量子点的光学性能及其发光二极管应用

采用氢氟酸(HF)原位注入法制备了InP/GaP/ZnS量子点。通过紫外/可见/近红外光谱、光致发光光谱、透射电镜、球差校正透射电镜、X射线衍射、X射线光电子能谱等测试手段分析了HF对InP量子点的发光性能影响。实验结果表明,HF刻蚀减少了量子点表面氧化缺陷状态,有效控制了InP核表面的氧化,并且原子配体形式的F-钝化了量子点表面的悬挂键,显著提升了量子点的光学性能。HF处理的InP/GaP/ZnS量子点具有最佳的发光性能,PLQY高达96%。此外,用HF处理InP/GaP/ZnS量子点制备的发光二极管,其发光的电流效率为6.63 cd/A,最佳外量子效率(EQE)为3.83%。

Compiling and Mapping an International Climate Change Database: Worlds of Gaps and Unevenness

Daily and weekly reporting events of climate change and impacts on populations, cultures, economies and politics at local, national, regional and international scales suggest the need to construct databases that will be useful in future scientific inquiry and global human/environmental policies. That need is evident in constructing a geographic or locational knowledge base that examines countries, regions and cities. This study constructs a database on the impacts of climate change using Google Scholar entries for 200 countries and capital cities. A series of maps reveal the vast unevenness in the database, especially between Global North and Global South countries. The discussion explores these sharp differences and suggests future research topics for much-needed global, interdisciplinary and international research.

环境质量视角下收入差距对经济增长的影响研究——基于环境质量中介与门槛效应的实证分析

缩小收入差距,提升环境质量,实现经济可持续增长是推动我国新时期高质量发展的本质要求。基于2009—2020年中国30个省份的面板数据,运用动态面板模型、中介效应模型、动态门限面板模型实证研究了收入差距对经济增长的影响,以及环境质量在二者关系中所发挥的中介效应与门槛效应。研究结果表明:收入差距的扩大对经济增长有明显的抑制作用;环境质量在收入差距影响经济增长的过程中起到了部分中介作用与单重门槛效应,随着环境质量改善收入差距对经济增长呈现先促进后抑制的特征。政府应当积极通过缩小收入差距,优化环境质量与收入差距的匹配模式来促进经济增长,实现中国经济的可持续发展。

数字治理下农民收入增长与收入分配效应

实现共同富裕要求兼顾“发展”与“共享”的双重目标,数字技术为乡村治理转型提供支撑。以中国乡村振兴综合调查(CRRS)数据为样本进行实证分析,结论如下:农民参与数字治理具有收入增长效应,能有效提升其收入水平,实现共同富裕所要求的“发展”目标。分位数回归与再中心化影响函数回归结果均表明农民参与数字治理具有收入分配效应,能够缩小农民内部收入差距,实现共同富裕所要求的“共享”目标。影响机制检验表明,农民参与数字治理将显著提高其信息获取能力,同时,数字治理参与对具有较低社会资本群体的收入赋能作用更显著。

我国教育投入产出对收入差距影响的实证研究

我国迅速发展的教育事业为经济社会发展做出了巨大贡献,为探究我国教育事业发展对收入差距产生的影响,选取1999-2020年我国31个省份相关数据,通过双固定效应模型、空间计量模型等方法展开实证分析。研究发现,教育投入会显著缩小本地区收入差距,教育产出显著地扩大了本地区的收入差距;机制分析结果表明,教育投入具有公平效应,且该过程会受到经济发展水平及政府其他资源配置能力的影响,教育产出更具马太效应,且该作用通过影响科技创新水平表现出来并受到劳动力市场情况的影响;空间计量结果表明,教育投入会缩小相邻地区收入差距,教育产出未对相邻地区收入差距产生作用。据此提出持续加大教育投入、继续发挥多次分配作用、政府政策发挥导向作用、完善其他配套政策等建议。

基于5GAP模型的高校食堂服务质量差距分析与对策探讨

食堂服务是高校后勤服务体系中最重要的环节之一,高校食堂管理必须要有的放矢地改进工作。5GAP模型是一种直接有效的服务环节分析工具,更注重找出内部的服务缺陷。在以往的高校食堂研究中,多以顾客满意度的外部视角分析服务质量问题,本文通过5GAP模型以内部视角分析发现引发高校食堂服务质量问题的根源,以期能对高校食堂服务质量的改进和提升起到一定作用。

实现共同富裕的一个路径探索:人力资本的增长与平衡效应检验

共同富裕是我国新发展阶段的一个远景目标,“富裕”和“共享”是实现共同富裕的关键。构造一个反映人力资本与城乡居民收入差距关系的理论模型,并基于经验证据检验人力资本通过增长效应和平衡效应推动“富裕”和“共享”,进而促进共同富裕的作用。研究发现,人力资本提升既有利于“蛋糕”做大,又能有效促进“蛋糕”更好地分配,显著提升了城乡居民可支配收入水平,且对农村居民收入的提升力度大于城镇居民,成为缩小城乡居民收入差距的关键变量,推动了“富裕”和“共享”目标的实现;中介效应检验证实了人力资本通过促进农村高技能劳动力流向城镇,间接推动城乡居民收入增长和差距缩小,从而实现其增长与平衡效应;分样本回归结果显示,人力资本的平衡效应在低收入省份更加明显,而在高收入省份不显著。

气隙偏心对同步发电机定子绕组温升特性的影响

为了分析同步发电机气隙偏心对定子绕组的铜耗及温升的影响规律。首先理论推导了正常情况和偏心下的磁通密度及相应的铜耗,分析了绕组的温升特性;然后建立了CS-5型故障模拟发电机的三维有限元模型,计算得到了发电机在不同负载和不同故障程度下定子绕组的铜耗和温度变化规律;最后在CS-5型故障模拟发电机上对定子绕组温度进行了实测,所得实验结果和仿真数据与理论分析结论基本一致。研究发现:定子绕组直线段温度高于端部温度;定子绕组的铜耗和温度在气隙偏心工况下均高于正常情况,且随着偏心量和负载的增加呈现升高趋势;在静偏心下靠近小气隙一侧的绕组温度高于其他部位。

青年职场“Gap day”现象探究

青年职场“Gap day”现象引起了社会的广泛关注和热烈讨论。青年职场“Gap day”现象的典型特征是:通过语言上的拼贴与再造,表达部分职业青年的困顿疲倦情绪;通过行为上的放空与逃离,排解青年在工作中积攒的情绪和压力;通过价值上的戏谑与自嘲,赋予青年的短暂休息以正向意义。青年职场“Gap day”现象的深层原因是:青年在高压生存环境中的“弹性姿态”、在加速社会运行中的“精神逃离”和在社会时钟齿轮下的“自我审视”。对青年职场“Gap day”现象的有效治理,既要着眼于青年发展,运用公共政策实现青年发展的普遍性诉求,又要立足于青年就业,采取切实措施促进青年实现高质量充分就业。

数字基础设施的家庭收入效应——基于中国家庭金融调查(CHFS)的实证研究

数字基础设施建设践行与彰显共同富裕的本质要求。基于2011—2019年五轮中国家庭金融调查(CHFS)数据,借助“宽带中国”战略准自然实验,研究了数字基础设施建设与家庭收入之间的关系。研究发现,数字基础设施建设显著提高了家庭收入,而且还有效抑制了收入差距。从作用机制来看,数字基础设施建设通过增加创业机会、就业机会,提高家庭收入,具有显著的“创业效应”和“就业效应”。数字基础设施建设的家庭收入效应在城市、城镇化率高的地区,年龄中等、受教育程度高的群体中更为显著,表现出明显的地区差异和人力资本差异。

大股东减持影响战略激进度吗?

企业通过维持适当的战略激进度以实现稳中求进,进而筑牢企业高质量发展的基石是当前理论研究和管理实践的重点议题之一。本文基于委托代理理论,以2008—2020年中国A股上市公司为样本,关注大股东减持和战略激进度二者之间的关系以及管理层代理效率在其中的调节作用。研究结果显示,大股东减持能够提高战略激进度,减持比例越大,减持后的战略激进度越高;同时,代理效率在这一过程中发挥着负向调节作用。进一步研究结果表明,绩效期望差距和高管团队稳定性在大股东减持与战略激进度的关系中起部分中介作用。异质性分析结果显示,在管理者为男性的企业、管理者学历较高的企业、两职分离的企业和衰退期企业中,大股东减持对战略激进度的提升作用更为明显。本文拓展了企业战略激进度的影响因素研究,深化了有关大股东减持经济后果的探讨,为企业所有者作出科学决策、防范战略风险提供了一定的参考。

城乡建设用地增减挂钩政策与城乡收入差距

在空间均衡视角下,建立理论模型分析城乡建设用地增减挂钩政策对城乡收入差距的影响,并通过实证分析进行政策评估的结果表明:增减挂钩政策能够提高城乡居民人均收入,但是对城市居民人均收入提高幅度更多,从而加大城乡收入差距。如果配套实施农村生产率提升的增减挂钩政策,在提高城乡居民人均收入的同时,这种综合性改革能够促使农村人均收入提高幅度更大,进而缩小城乡收入差距。随后,基于2000—2016年省级面板数据,采用逐期双重差分法与合成控制法分别评估城乡建设用地增减挂钩政策与配套实施农村生产率提升的增减挂钩政策对城乡收入差距影响的实证结果发现:自2006年实施增减挂钩政策后,增减挂钩试点省份的城乡收入差距均值提升0.125,达到2.820;自2008年实施配套农村生产率提升的增减挂钩政策后,重庆市的城乡收入差距均值下降0.261,达到3.043。基于此,在城乡融合背景下,我们应建立健全城乡统一建设用地市场制度。

我国不同付费模式信用评级校验机制研究

我国债券市场刚性兑付被打破后,不断出现高评级债券违约事件。为此,监管部门积极发展多种评级,以期提高债券评级质量。通过理论建模与实证分析,研究了不同付费模式信用评级如何综合发挥校验作用。基于博弈模型的理论分析发现,不同付费模式评级发挥校验作用的机制在于投资者的反应:当投资者付费和发行人付费两种模式评级差值增大,投资者不以单一评级结果进行债券定价,而是根据评级差值调整债券价格。基于2011—2020年企业债评级数据的经验证据显示,随着评级差值增大,发行人付费评级机构会降低后续评级,且评级差值对单一信用评级与债券信用利差之间的负向关系具有抑制作用。进一步检验发现,发行人付费评级机构提供的偏正面的私有信息会降低债券信用利差,而以中债资信为代表的投资者付费评级机构提供的私有信息则不会显著影响债券信用利差,均体现出单一评级模式在定价方面的弊端。因此,监管部门应继续鼓励发展投资者付费评级模式,并鼓励机构投资者发展内部评级,以充分发挥多种评级模式的交叉校验作用。

金融结构优化、财政分权与共同富裕

立足金融结构优化背景,借助我国省级面板数据考察金融结构优化对共同富裕的影响。研究发现:金融结构优化能够赋能共同富裕,且经过内生性与一系列稳健性检验后,该结论依然成立;门槛回归结果表明,财政分权可正向调节金融结构优化对共同富裕的影响。进一步研究得出,金融结构优化对共同富裕影响呈“边际效应递增”的非线性特征;金融结构优化积极效应在不同区域和不同金融发展水平地区存在显著差异。

共同富裕愿景下增进农村低收入人口福利的政策创新——基于三次分配分析框架

面向全体人民共同富裕的伟大愿景目标,迫切需要对标共同富裕、研判福利差距,并进行制度性的回应。三次分配制度是改善农村低收入人口福利差距、促进农村低收入人口持续增收、实现全体人民共同富裕的有效手段。中国农村和农民在不断分化转型,三次分配的契合性也不尽相同。脱贫攻坚期间,中国基于三次分配的不同着力点围绕农村低收入群体展开了一系列政策实践,但是存在初次分配效率不高、再分配水平低、第三次分配尚未找到切入点、不同层次分配间协同性不足等问题。未来政策调整应当以加大农业就业准入门槛、提高农村低收入群体的劳动报酬、扩大农村非农就业机会作为初次分配的着力点;以强化农村低收入人口的转移支付力度、提高基本公共服务和社会保障均等化的深度与广度、完善农业支持与资源保护政策等作为再分配的着力点;以丰富第三次分配的实现形式、强化第三次分配与初次分配、再分配间的协同配合作为第三次分配的创新着力点。