Prediction of discharge in a tidal river using the LSTM-based sequence-to-sequence models

The complexity of river-tide interaction poses a significant challenge in predicting discharge in tidal rivers.Long short-term memory(LSTM)networks excel in processing and predicting crucial events with extended intervals and time delays in time series data.Additionally,the sequence-to-sequence(Seq2Seq)model,known for handling temporal relationships,adapting to variable-length sequences,effectively capturing historical information,and accommodating various influencing factors,emerges as a robust and flexible tool in discharge forecasting.In this study,we introduce the application of LSTM-based Seq2Seq models for the first time in forecasting the discharge of a tidal reach of the Changjiang River(Yangtze River)Estuary.This study focuses on discharge forecasting using three key input characteristics:flow velocity,water level,and discharge,which means the structure of multiple input and single output is adopted.The experiment used the discharge data of the whole year of 2020,of which the first 80%is used as the training set,and the last 20%is used as the test set.This means that the data covers different tidal cycles,which helps to test the forecasting effect of different models in different tidal cycles and different runoff.The experimental results indicate that the proposed models demonstrate advantages in long-term,mid-term,and short-term discharge forecasting.The Seq2Seq models improved by 6%-60%and 5%-20%of the relative standard deviation compared to the harmonic analysis models and improved back propagation neural network models in discharge prediction,respectively.In addition,the relative accuracy of the Seq2Seq model is 1%to 3%higher than that of the LSTM model.Analytical assessment of the prediction errors shows that the Seq2Seq models are insensitive to the forecast lead time and they can capture characteristic values such as maximum flood tide flow and maximum ebb tide flow in the tidal cycle well.This indicates the significance of the Seq2Seq models.

City Network Evolution Characteristics of Smart Industry: Evidence from Yangtze River Delta, China

The dual-path model of industrial evolution and spatial progression has been widely acknowledged and incorporated into the strategic planning to promote the development of urban industries and regional collaborations.However,current research on inter-enter-prise city networks mainly focuses on the single sector of flows on all enterprise branches,such as product value chains and production factors,but neglects that of particular industry department.Built upon the new economic geography and city networks theory,this paper develops a methodological framework that focuses on the analysis of city network evolution characteristics of smart industry.Particu-larly,a conceptual model of smart industry enterprise-industry-city is proposed and then applied to a case study of smart industry in the Yangtze River Delta Region,China.Using enterprise supplier-customer data,a city network of smart industry is constructed and sub-sequently analyzed with the proposed model.Findings indicate that the smart industry network in Yangtze River Delta Region exhibits a hierarchical structure and the expansion of the network presents a small-world network characteristic.The study not only makes a meth-odological contribution for revealing the industrial and spatial evolution path of the current smart industry,but also provides empirical support for the formulation of new economic development policies focused on smart industries,demonstrating the role of city clusters as carriers of regional synergistic development.

Structural Characteristics and Influencing Factors of Carbon Emission Spatial Association Network:A Case Study of Yangtze River Delta City Cluster,China

City cluster is an effective platform for encouraging regionally coordinated development.Coordinated reduction of carbon emissions within city cluster via the spatial association network between cities can help coordinate the regional carbon emission management,realize sustainable development,and assist China in achieving the carbon peaking and carbon neutrality goals.This paper applies the improved gravity model and social network analysis(SNA)to the study of spatial correlation of carbon emissions in city clusters and analyzes the structural characteristics of the spatial correlation network of carbon emissions in the Yangtze River Delta(YRD)city cluster in China and its influencing factors.The results demonstrate that:1)the spatial association of carbon emissions in the YRD city cluster exhibits a typical and complex multi-threaded network structure.The network association number and density show an upward trend,indicating closer spatial association between cities,but their values remain generally low.Meanwhile,the network hierarchy and network efficiency show a downward trend but remain high.2)The spatial association network of carbon emissions in the YRD city cluster shows an obvious‘core-edge’distribution pattern.The network is centered around Shanghai,Suzhou and Wuxi,all of which play the role of‘bridges’,while cities such as Zhoushan,Ma'anshan,Tongling and other cities characterized by the remote location,single transportation mode or lower economic level are positioned at the edge of the network.3)Geographic proximity,varying levels of economic development,different industrial structures,degrees of urbanization,levels of technological innovation,energy intensities and environmental regulation are important influencing factors on the spatial association of within the YRD city cluster.Finally,policy implications are provided from four aspects:government macro-control and market mechanism guidance,structural characteristics of the‘core-edge’network,reconfiguration and optimization of the spatial layout of the YRD city cluster,and the application of advanced technologies.

Impact of urban expansion on regional temperature change in the Yangtze River Delta

Based on non-radiance-calibrated DMSP/OLS nighttime light imagery from 1992 to 2003, urban land area statistical data, meteorological data and land surface temperature data retrieved by MODIS and NOAA/AVHRR data, the influence of urbanization on regional climatic trend cf temperature in the Yangtze River Delta （YRD） was analyzed. Conclusions are as follows： 1） There is a significant urbanization process from 1992 to 2003 in the YRD. Four city clusters of Nanjing-Zhenjiang-Yangzhou, Suzhou-Wuxi-Changzhou, Shanghai and Hangzhou Bay form a zigzag city belt. The increase rate of annual mean air temperature in city-belt is 0.28-0.44℃/10a from 1991 to 2005, which is far larger than that of non-city-belt. 2） The urban heat island （UHI） effect on regional mean air temperature in different seasons is summer〉autumn〉spring〉winter. 3） The UHI intensity and the urban total population logarithm are creditably correlated. 4） The UHI effect made the regional annual mean air temperature increased 0.072℃ from 1961 to 2005, of which 0.047℃ from 1991 to 2005, and the annual maximum air temperature increased 0.162℃, of which 0.083℃ from 1991 to 2005. All these indicating that the urban expansion in the YRD from 1991 to 2005 may be regarded as a serious climate signal.

Spatial Pattern and Heterogeneity of Port & Shipping Service Enterprises in the Yangtze River Delta,2002–2016

Using the ‘theoretical hypothesis—empirical study—case verification' method, this paper studies the spatial distribution and differentiation of port & shipping service enterprises(PSSE), as well as the variation process and underlying mechanism in the Yangtze River Delta(YRD). First, through inductive and deductive reasoning, we propose the following hypothesis: the regional distribution of different types of PSSE would show different spatial agglomeration-decentralization tendency; and there would be distinct regional differentiation in the industrial structure of the enterprises. Second, based on data obtained from enterprises, empirical research is conducted using Gini coefficient and spatial interpolation simulation methods. Results show that: 1) The overall enterprise distribution is decentralized within a city. 2) Different types of enterprises show different spatial agglomeration-decentralization tendencies. At 3000 m×3000 m grid scale, there is an agglomeration tendency along seas and rivers in the spatial distribution of enterprises. Shanghai has been identified consistently as a hot spot. 3) There is significant regional differentiation in 12 port cities with respect to the industrial structures of enterprises. Finally, the transportization and the increase of shipping service demand, the globalization and the expansion of multinational corporate activities, the hierarchization and the cooperation among port cities as well as the decentralization and the behavioral difference between the central and local states can be seen as main driving mechanism of the spatial phenomenon.

Urban Development and Water Management in the Yangtze River Delta

Throughout the history of the world, the development of the cities are related to the large water systems and the ocean. Where the river is abundant, the trade and regional centres could be formed. However, along with the prosperity of the water-cities, massive urban construction and environmental issues are enormous challenges in human process. A “scientific” urban planning, “Sponge City”, “Resilient City”, regional and urban culture and characteristics get more and more attention. The theme of “water and city” is clearly of great historical value and practical significance for the new resilient urban and water management strategies. The paper will summarize characteristics of geographical, historical, socio-cultural and political realms in metropolitan deltas and the historical governance as well as the recent developments in the Yangtze River Delta. It will introduce urban development and water management in four water cities: the canal and the city-Yangzhou, the river and the city-Nanjing, the lake and the city-Suzhou and the sea and the city-Shanghai. And then it will analyze the inner motivation of the interaction between water and cities in Yangtze River Delta. Furthermore, learning from successful historical experiences, the paper will provide suggestions for future sustainable urban development.

长江中下游城市内涝与雨季污染协同治理对策

针对长江中下游城市内涝与雨季污染协同治理的突出问题,对城市水安全、雨季水体返黑返臭风险和河湖水生态退化三方面存在的问题进行了论述。发现长江中下游城市河网密度高、降水量大、暴雨多发,同时人口密集、经济发展水平高,内涝、污染、生态退化等水问题突出;城市内涝频发,雨季污染造成某些城市水体局部返黑返臭,严重影响城市水环境品质,成为制约长江中下游城市绿色发展的重要瓶颈问题。提出了建立三级内涝协同防治体系、构建城市“绿-灰-蓝”设施耦合工程体系、协同推进水体品质提升与生态修复等建议。

创新企业的中微观集聚特征及邻近性机制研究——基于长三角地区4座典型城市的实证

在创新型经济重构空间使用逻辑的背景下,以解析城市内部创新要素的集聚和选址为出发点,构建创新企业集聚的邻近性框架,运用中小型创新企数据以及问卷调查数据,对长三角上海、南京、杭州、苏州4座典型的创新型城市进行研究,透视创新在空间利用上的新变化和新需求。研究得出以下结论:(1)集聚趋势。在我国内城更新与新城开发同步推进的城镇化语境下,创新企业的集聚兼具回归城区和近郊生长的双重动力,而且低密度、品质高的新兴园区与创新人才的需求形成了较好契合。(2)结构演化。创新企业的集聚结构与城市的空间转型、功能演化形成紧密互动。城市的区域职能分工、空间结构对企业的集聚有深刻影响。创新企业的集聚强度由中心向外围衰减,形成半径为1~3 km的核心-边缘结构。(3)区位逻辑。除政策、产业等传统因素外,创新企业不仅侧重于向“年轻集群”和应用导向的科研集群集聚,而且呈现出明确的生活指向,品质、氛围等软性因素成为不可忽视的高阶需求。

智力资本对长江经济带智慧城市建设的作用研究

智慧城市建设是未来我国城市高质量可持续发展的重要选择,也是现阶段我国推进新型工业化、发展新质生产力的重要途径。将智慧城市建设的技术中心主义和人本主义相结合,从资本、人、技术、空间建构智慧城市要素指标,阐释智力资本通过人力素质、智力产出、科技投入、开放水平四大方式促进智慧城市经济增长的作用机理。构建生产函数模型,运用长江经济带2002—2022年面板数据分析11个核心城市智力资本对智慧城市经济增长的影响。结果表明:不同智慧城市的未来发展存在共性与特性,长江经济带智力资本的集聚对智慧城市经济增长有显著的促进作用,其分解要素对不同区域及不同级别智慧城市的经济增长作用呈异质性,而开放水平是现阶段最为重要的因素。在此基础上,提出有利于长江经济带智慧城市经济发展的对策建议:从数字孪生城市建设、产业数字化发展、数字化转型要素集聚等方面入手,实施不同区域、不同等级城市分类指导的智慧城市发展战略;以智慧城市建设的市场需要为导向,聚焦智力产出的市场转化,发挥智力资本的影响推动作用;推进智力资本各要素的有效整合,加强“技术+人本”互嵌,促进数据要素跨域流通。

Analysis of city centrality based on entropy weight TOPSIS and population mobility:A case study of cities in the Yangtze River Economic Belt

Based on statistical data and population flow data for 2016,and using entropy weight TOPSIS and the obstacle degree model,the centrality of cities in the Yangtze River Economic Belt(YREB)together with the factors influencing centrality were measured.In addition,data for the population flow were used to analyze the relationships between cities and to verify centrality.The results showed that:(1)The pattern of centrality conforms closely to the pole-axis theory and the central geography theory.Two axes,corresponding to the Yangtze River and the Shanghai-Kunming railway line,interconnect cities of different classes.On the whole,the downstream cities have higher centrality,well-defined gradients and better development of city infrastructure compared with cities in the middle and upper reaches.(2)The economic scale and size of the population play a fundamental role in the centrality of cities,and other factors reflect differences due to different city classes.For most of the coastal cities or the capital cities in the central and western regions,factors that require long-term development such as industrial facilities,consumption,research and education provide the main competitive advantages.For cities that are lagging behind in development,transportation facilities,construction of infrastructure and fixed asset investment have become the main methods to achieve development and enhance competitiveness.(3)The mobility of city populations has a significant correlation with the centrality score,the correlation coefficients for the relationships between population mobility and centrality are all greater than 0.86(P<0.01).The population flow is mainly between high-class cities,or high-class and low-class cities,reflecting the high centrality and huge radiating effects of high-class cities.Furthermore,the cities in the YREB are closely linked to Guangdong and Beijing,reflecting the dominant economic status of Guangdong with its geographical proximity to the YREB and Beijing's enormous influence as the national political and cultural center,respectively.

粗骨料最大粒径对水工混凝土变形性能及长期耐久性的影响

为研究不同粗骨料最大粒径对水工混凝土的变形影响,探明国家标准规定的骨料粒级能否满足水工混凝土的要求,依托引江济淮工程,开展了粗骨料最大粒径为31.5 mm和40.0 mm的混凝土变形试验,探究2种骨料粒级混凝土长期耐久性能演变规律。结果表明:采用最大粒径31.5 mm骨料的混凝土极限拉伸值和弹性模量略大,动态疲劳性能较好;采用最大粒径40 mm骨料的混凝土干燥收缩以及自生体积变形小;2种不同骨料最大粒径的混凝土徐变度相当;采用最大粒径31.5 mm骨料的混凝土长期抗渗性和长期抗冻性均优于采用最大粒径40 mm骨料的混凝土。因此,最大粒径31.5 mm骨料应用于水工混凝土时,能满足水工混凝土性能要求且动态疲劳寿命及耐久性更优,但需要注意混凝土开裂问题。

技能型社会背景下世界技能大赛获奖选手的职业发展思考——对长三角四省市获奖选手的分析

基于技能型社会建设背景,对第41~46届世赛长三角四省市获奖选手的职业情况进行统计分析,得出其就业相对稳定、教职为职业首选、技能培训为主要工作内容和近年就业愈加灵活四方面的主要职业特征。技能型社会建设对世赛获奖选手提出了精进自身技能、完善技能标准、改善技能环境和拓展国际影响四方面的新要求;获奖选手在职业发展中需要解决来自职业技能、职业视野以及职业路径三个方面的主要挑战。针对上述要求和挑战,论文提出了完善政策内容制定、搭建学习培训平台、优化实践内外环境,以及统筹设计选手职业发展路径等具体改革建议。

低碳城市试点与长江经济带经济高质量发展:影响机制与实证检验

绿色是经济高质量发展的鲜明底色,而作为我国生态文明建设的重要举措,低碳城市试点有助于推动经济高质量发展。本文采用长江经济带2004-2020年108个城市市级面板数据,使用多时点双重差分模型,实证探究低碳城市试点对经济高质量发展的影响效应,研究发现:(1)低碳城市试点有利于提升长江经济带经济高质量发展水平,且政策效果具有滞后性,该结论在进行一系列稳健性检验后依旧成立;(2)异质性分析表明,从区位特征来看,低碳城市试点对长江上游地区经济高质量发展水平的提升效果更明显;从城市人口规模来看,低碳城市试点对人口规模较大城市的政策效果往往更明显;(3)机制分析表明,吸引外商直接投资是低碳城市试点促进长江经济带经济高质量发展的重要传导机制。

新时代港口与城市协调发展研究--以长三角地区为例

研究聚焦经典的港城关系问题,在新时代背景下重新审视港口与城市互动发展的新内涵。以长三角为案例区域,利用耦合度、耦合协调度模型,定量测度2013年以来长三角地区24个港口与城市的协调发展水平,结果显示:长三角地区港口与城市耦合协调度整体上升明显,呈现“高水平耦合、中水平协调”的特征;在省域尺度,三省一市港城关系耦合度和耦合协调度均存在明显的梯度差异,由东向西逐渐下降,具体表现为C/D上海>C/D江苏>C/D浙江>C/D安徽;在城市尺度,长三角地区绝大部分港口与城市已经进入高度耦合、良性发展阶段,仅有舟山和池州港城耦合情况不理想。耦合协调度形成显著的4个等级,包括:以上海为代表的极度协调型,以苏州、宁波、南京、无锡为代表的高度协调型,以杭州、南通、扬州、芜湖等12个城市为代表的中度协调型,以湖州、台州、合肥、安庆等7个城市为代表的低度协调型。最后从统筹协调、港城融合、政策创新、开放包容等方面提出长三角地区港城协调发展的路径。

数字经济、科技创新与出口技术复杂度--基于长三角地区41个城市的实证

基于2012-2021年长三角地区41个城市的面板数据探讨数字经济对制造业出口技术复杂度的影响效应和科技创新在此影响过程中的中介效应,考察了科技金融的调节效应。数字经济显著推动长三角地区城市制造业出口技术复杂度的提升,但提升作用因环境规制严苛程度、人力资本水平、中心区城市地位属性的差异而存在异质性。数字经济通过科技创新推动制造业出口技术复杂度提升,金融科技在数字经济推动长三角地区城市制造业出口技术复杂度提升中发挥负向调节效应。提高制造业出口技术复杂度,要加快发展数字经济,因地制宜实施发展政策,助力科技创新与金融服务的高质量融合发展。

Large-scale atmospheric singularities and summer long-cycle droughts-floods abrupt alternation in the middle and lower reaches of the Yangtze River

The daily precipitation data at 720 sta- tions over China for the 1957―2003 period during summer (May―August) are used to investigate the summer subseasonal long-cycle droughts-floods abrupt alternation (LDFA) phenomenon and a long-cycle droughts-floods abrupt alternation index (LDFAI) in the middle and lower reaches of the Yangtze River (MLYRV) is defined to quantify this phenomenon. The large-scale atmospheric circula- tion features in the anomalous LDFA years are ex- amined statistically. Results demonstrate that the summer droughts-to-floods (DTF) in the MLYRV usually accompany with the more southward western Pacific subtropical high (WPSH), negative vorticity, strong divergence, descending movements develop- ing and the weak moisture transport in the low level, the more southward position of the South Asia high (SAH) and the westerly jets in the high level during May―June, but during July―August it is in the other way, northward shift of the WPSH, positive vorticity, strong convergence, ascending movements and strong moisture transport in the low level, and the northward shift of the SAH and the westerly jets in the high level. While for the summer floods-to-droughts (FTD) in the MLYRV it often goes with the active coldair mass from the high latitude, positive vorticity, strong convergence, ascending movement develop- ing and the strong moisture transport in the low level, and the SAH over the Tibetan Plateau in the high level, but during July―August it is often connected with the negative vorticity, strong divergence, de- scending movements developing and the weak moisture transport in the low level, the remarkable northward shift of the WPSH, the SAH extending northeastward to North China and the easterly jets prevailing in the high level over the MLYRV. In addi- tion, the summer LDFA in the MLYRV is of significant relationship with the Southern Hemisphere annual mode and the Northern Hemisphere annual mode in the preceding February, which offers some predictive signals for the summer LDFA forecasting in the MLYRV.

高铁网络发展下的站城空间与功能关系研究--以长三角地区为例

在过去近20年里,中国高铁网络化已成为城市和区域空间发展的重要推动力,各级政府也在不同层面上实施了高铁站区建设与城市空间协同发展策略。为此,建立站城空间及站城功能联系的分析框架,以长三角为案例区,探讨不同类型高铁站的站区发育及站城关系特征。结果表明,长三角地区高铁站城联系具有较大的分异特征,大多站区功能发育水平较低,区域中心城市和部分地级城市与其主要高铁站区之间相互强化发展,而其他高铁城市与站区之间功能联系有待提升,不同类型高铁站的站城功能联系发育水平受站区、城市和区域因素的交互影响。结合站区发展潜力、地区差异化的高铁出行需求、城市空间发展规划,建议提升站城交通服务质量、分类分级培育站区主导功能、优化站城功能联系。

长三角合作共建园区转型路径与机制——基于“同质多形”视角

合作共建园区的转型发展作为重要区域治理现象在学术界备受关注。本文采用半结构化访谈法和文本分析法,援引“同质多形”理论视角并构建研究框架,尝试从尺度、网络、领域等多个维度揭示长三角合作共建园区转型的内在动力及其新发展趋势。研究发现:①长三角合作共建园区多维特征处于动态演化中,资本需求与行政治理困境共同构成最为关键的演化动力。园区经历了以企业转移为目标的早期形成阶段、2010年后的波折发展阶段以及2016年后以多元伙伴议程为导向的创新转型阶段,园区的转型发展由不同时期经济发展需求与行政治理困境共同推动。②长三角合作共建园区治理方式从政府间协同转向多元主体网络行动,使园区的尺度、网络、领域特征从早期迁出地主导的单中心治理方式向多元化发展。③长三角合作共建园区的建设从突出专业化经济优势转向囊括创新、生产、居住等要素的综合性整体系统转变,是当前区域治理日趋复杂的缩影,国家到地方、政府到市场的不同行动主体都参与其中。总之,本文揭示了合作共建园区治理的新趋势,并强调同质多形框架在认识与推动当前合作共建园区新发展中的理论与实践价值。

“跨界合作园区热”:尺度重组与空间转型——以长江三角洲地区为例

21世纪初以来,中国城市的增长经历了从竞争到合作的转变,“跨界合作园区热”接替“开发区热”成为转型期城市空间重构过程的集中展示。(1)研究立足长三角跨界合作园区的转型发展历程,探讨跨界合作园区历经的转移工业园、跨界新城到合作创新区的政策发展历程,及其空间转型的基本趋势;(2)基于空间转型与合作主体尺度重组活动的紧密联系,进一步探讨空间转型背后尺度重组的动力机制,并提出尺度上推、尺度融合与尺度多元化3个重组阶段及其所形成的托管、合署与企业式3种治理模式;(3)研究建构了跨界合作园区尺度权力重组与空间转型的逻辑框架,并从动态引导的政策支撑体系、劳酬对等的利益协调机制、省-地监管的分层管控机制等方面提出政策建议。

上海市洪涝灾害损失对长江下游地区的辐射影响

随着区域经济一体化程度的加深,跨区域产业关联损失已成为灾害损失评估不容忽视的一部分,准确量化洪涝灾害损失的辐射影响对于制定防灾减灾措施、减少洪涝灾害损失具有重要作用。在系统评估了不同暴雨重现期情景下上海市减停产损失的基础上,采用两区域投入产出模型,测算和分析了长江下游地区不同省(直辖市)的区域内乘数效应、区域间溢出效应和区域间反馈效应,量化了上海市洪涝灾害损失对长江下游地区的辐射影响。结果表明,暴雨重现期10 a、20 a、30 a、50 a、100 a时,上海市的减停产损失分别为14.01亿元、19.83亿元、25.58亿元、33.82亿元和46.24亿元;在长江下游地区,上海市与浙江省的经济相互影响强度最大,且跨区域产业关联损失以溢出效应为主导;上海市发生洪涝灾害时,跨区域波及效应将导致长江下游地区损失增加26.24%。因此,在城市之间联系日益紧密的情况下,不仅要关注洪涝灾害对自身的影响,同时也要采取有效措施减少地域之间的波及影响,以便更有效地开展防灾减灾工作。