Can urban forests provide acoustic refuges for birds?Investigating the influence of vegetation structure and anthropogenic noise on bird sound diversity

As a crucial component of terrestrial ecosystems,urban forests play a pivotal role in protecting urban biodiversity by providing suitable habitats for acoustic spaces.Previous studies note that vegetation structure is a key factor influencing bird sounds in urban forests;hence,adjusting the frequency composition may be a strategy for birds to avoid anthropogenic noise to mask their songs.However,it is unknown whether the response mechanisms of bird vocalizations to vegetation structure remain consistent despite being impacted by anthropogenic noise.It was hypothesized that anthropogenic noise in urban forests occupies the low-frequency space of bird songs,leading to a possible reshaping of the acoustic niches of forests,and the vegetation structure of urban forests is the critical factor that shapes the acoustic space for bird vocalization.Passive acoustic monitoring in various urban forests was used to monitor natural and anthropogenic noises,and sounds were classified into three acoustic scenes(bird sounds,human sounds,and bird-human sounds)to determine interconnections between bird sounds,anthropogenic noise,and vegetation structure.Anthropogenic noise altered the acoustic niche of urban forests by intruding into the low-frequency space used by birds,and vegetation structures related to volume(trunk volume and branch volume)and density(number of branches and leaf area index)significantly impact the diversity of bird sounds.Our findings indicate that the response to low and high frequency signals to vegetation structure is distinct.By clarifying this relationship,our results contribute to understanding of how vegetation structure influences bird sounds in urban forests impacted by anthropogenic noise.

Analysis of Urban Agglomeration Network Structure Based on Baidu Migration Data: A Case Study of the Guangdong-Hong Kong-Macao Greater Bay Urban Agglomeration

The inter-city linkage heat data provided by Baidu Migration is employed as a characterization of inter-city linkages in order to facilitate the study of the network linkage characteristics and hierarchical structure of urban agglomeration in the Greater Bay Area through the use of social network analysis method.This is the inaugural application of big data based on location services in the study of urban agglomeration network structure,which represents a novel research perspective on this topic.The study reveals that the density of network linkages in the Greater Bay Area urban agglomeration has reached 100%,indicating a mature network-like spatial structure.This structure has given rise to three distinct communities:Shenzhen-Dongguan-Huizhou,Guangzhou-Foshan-Zhaoqing,and Zhuhai-Zhongshan-Jiangmen.Additionally,cities within the Greater Bay Area urban agglomeration play different roles,suggesting that varying development strategies may be necessary to achieve staggered development.The study demonstrates that large datasets represented by LBS can offer novel insights and methodologies for the examination of urban agglomeration network structures,contingent on the appropriate mining and processing of the data.

The Study on the Evolution of Urban Spatial Structure in Zhuhai City Based on Spatial Syntax

With the deepening of the Guangdong-Hong Kong-Macao Greater Bay Area strategy and the accelerated integration and development of the east and west sides of the Pearl River Estuary,Zhuhai’s hub position is becoming more and more prominent.The city of Zhuhai has a dense water network and is divided into two urban areas,the east and the west,under the influence of the Mordor Gate waterway.Based on the theory of spatial syntax,this paper carries out an analytical study on the urban spatial structure of Zhuhai,identifies the distribution characteristics of urban POIs,and provides theoretical support for the urban development of Zhuhai.

How Does Urban Shrinkage Affect Land Use Efficiency?A Case Study of Shrinking Cities in Northeast China

The effect of urban shrinkage has gradually become a new topic.Theoretically,urban shrinkage may exert great influence on land use efficiency(LUE)through various urban subsystems,but there is currently limited research examining these pathways.Using the Super-SBM-Undesirable model and the Structural Equation Model(SEM),this study calculates the LUE of shrinking cities in Northeast China and simulates the process of urban shrinkage affecting LUE.To quantify the process of urban shrinkage affecting LUE,three mediation variables,namely the economy,public services,and innovation,are used as latent variables to apply SEM.The results show that urban shrinkage will affect LUE through a direct path and indirect paths.In the direct path,urban shrinkage leads to an improvement in LUE.In the indirect paths,the economy and innovation will transmit the negative effect of urban shrinkage on LUE,while public services will reverse this effect.An important contribution of this study is that it quantifies the paths of urban shrinkage affecting LUE,thereby expanding the understanding of urban shrinkage effect and laying a foundation for the sustainable development of shrinking cities.

The Tension Cosmology, Largest Cosmic Structures and Explosions of Supernovae from SST

Here, using the Scale-Symmetric Theory (SST) we explain the cosmological tension and the origin of the largest cosmic structures. We show that a change in value of strong coupling constant for cold baryonic matter leads to the disagreement in the galaxy clustering amplitude, quantified by the parameter S8. Within the same model we described the Hubble tension. We described also the mechanism that transforms the gravitational collapse into an explosion—it concerns the dynamics of virtual fields that lead to dark energy. Our calculations concern the Type Ia supernovae and the core-collapse supernovae. We calculated the quantized masses of the progenitors of supernovae, emitted total energy during explosion, and we calculated how much of the released energy was transferred to neutrinos. Value of the speed of sound in the strongly interacting matter measured at the LHC confirms that presented here model is correct. Our calculations show that the Universe is cyclic.

Different Turbulent Regimes and Vertical Turbulence Structures of the Urban Nocturnal Stable Boundary Layer

Turbulence in the nocturnal boundary layer(NBL)is still not well characterized,especially over complex underlying surfaces.Herein,gradient tower data and eddy covariance data collected by the Beijing 325-m tower were used to better understand the differentiating characteristics of turbulence regimes and vertical turbulence structure of urban the NBL.As for heights above the urban canopy layer(UCL),the relationship between turbulence velocity scale(VTKE)and wind speed(V)was consistent with the“HOckey-Stick”(HOST)theory proposed for a relatively flat area.Four regimes have been identified according to urban nocturnal stable boundary layer.Regime 1 occurs where local shear plays a leading role for weak turbulence under the constraint that the wind speed V<VT(threshold wind speed).Regime 2 is determined by the existence of strong turbulence that occurs when V>VT and is mainly driven by bulk shear.Regime 3 is identified by the existence of moderate turbulence when upside-down turbulence sporadic bursts occur in the presence of otherwise weak turbulence.Regime 4 is identified as buoyancy turbulence,when V>VT,and the turbulence regime is affected by a combination of local wind shear,bulk shear and buoyancy turbulence.The turbulence activities demonstrated a weak thermal stratification dependency in regime 1,for which within the UCL,the turbulence intensity was strongly affected by local wind shear when V<VT.This study further showed typical examples of different stable boundary layers and the variations between turbulence regimes by analyzing the evolution of wind vectors.Partly because of the influence of large-scale motions,the power spectral density of vertical velocity for upsidedown structure showed an increase at low frequencies.The upside-down structures were also characterized by the highest frequency of the stable stratifications in the higher layer.

Research on the hierarchical structure of the metropolitan system and economic development of the provincial capital urban circle in Shandong

Regional development is the trend for future urbanization,and the urban circle is a highly efficient economic spatial pattern of regional development.This study selects statistical data of urban area population,GDP,and the output value of tertiary industry for seven cities in China- Jinan,Zibo,Tai'an,Laiwu,Dezhou,Liaocheng,and Binzhou- in the Shandong provincial capital urban circle from 2005 to 2009.It uses the principles and Zipf model,rank-size rule,and Lotka logarithmic model to analyze and study the hierarchical structure of the metropolitan system and economic development of the Shandong provincial capital urban circle.Based on the above research,this paper provides references for decisionmaking on enhancement of the metropolitan system structure,improvement in core city primacy index,the optimal adjustment of industrial structure and the optimal allocation of essential resources.

An Application of the RAMS/FLUENT System on the Multi-Scale Numerical Simulation of the Urban Surface Layer—A Preliminary Study

The Regional Atmospheric Modeling System （RAMS） and the computational fluid dynamics （CFD） codes known as FLUENT are combinatorially applied in a multi-scale numerical simulation of the urban surface layer （USL）. RAMS and FLUENT are combined as a multi-scale numerical modeling system, in which the RAMS simulated data are delivered to the computational model for FLUENT simulation in an offline way. Numerical simulations are performed to present and preliminarily validate the capability of the multi-scale modeling system, and the results show that the modeling system can reasonably provide information on the meteorological elements in an urban area from the urban scale to the city-block scale, especially the details of the turbulent flows within the USL.

Bioinspired fish-scale-like magnesium composites strengthened by contextures of continuous titanium fibers:Lessons from nature

Natural fish scales demonstrate outstanding mechanical efficiency owing to their elaborate architectures and thereby may serve as ideal prototypes for the architectural design of man-made materials.Here bioinspired magnesium composites with fish-scale-like orthogonal plywood and double-Bouligand architectures were developed by pressureless infiltration of a magnesium melt into the woven contextures of continuous titanium fibers.The composites exhibit enhanced strength and work-hardening ability compared to those estimated from a simple mixture of their constituents at ambient to elevated temperatures.In particular,the double-Bouligand architecture can effectively deflect cracking paths,alleviate strain localization,and adaptively reorient titanium fibers within the magnesium matrix during the deformation of the composite,representing a successful implementation of the property-optimizing mechanisms in fish scales.The strength of the composites,specifically the effect of their bioinspired architectures,was interpreted based on the adaptation of classical laminate theory.This study may offer a feasible approach for developing new bioinspired metal-matrix composites with improved performance and provide theoretical guidance for their architectural designs.

What are the underlying causes and dynamics of land use conflicts in metropolitan junction areas?A case study of the central Chengdu–Chongqing region in China

Land use conflicts(LUCs),as a spatial manifestation of the conflicts in the human-land relationships,have a profound impact on regional sustainable development.For China’s metropolitan junction areas(MJAs),the existence of“administrative district economies”has made the issue of LUCs more prominent.Based on a case study of the central Chengdu–Chongqing region,we conducted an exploratory spatial data analysis of the evolutionary process of regional LUCs.Furthermore,structural equation modeling was utilized to analyze the dynamic mechanism of LUCs in MJAs,with a particular emphasis on exploring the influences of administrative boundary.The results showed that from 2010 to 2020,LUCs in the central Chengdu–Chongqing region continued to worsen,and the spatial process conflict and spatial structure conflict indices increased by more than 30.0%.The intensification of LUCs in the central Chengdu–Chongqing region from 2010 to 2020 was mainly the result of the deterioration of conflicts in evaluation units with low conflict levels.LUCs in China’s metropolitan areas generally presented a circular gradient distribution,weakening from the core to the periphery,but there were some strong isolated conflict zones in the outer regions.LUCs in China’s MJAs were the result of interactions among multiple factors,e.g.,natural environment,socio-economic development,policy and institutional processes,and administrative boundary effects.Administrative boundary affected the flow of socio-economic elements,changing the supply-and-demand competition of stakeholders for land resources,consequently exerting an indirect influence on LUCs.This study advances the theory of the dynamic mechanism of LUCs,and provides theoretical support for the governance of these conflicts in transboundary areas.

Spatial pattern of urban-rural integration in China and the impact of geography

Urban-rural integration (URI) is a global challenge that is highly related to inequalities, poverty, economic growth, and other Sustainable Development Goals (SDGs). Existing research has evaluated the extent of URI and explored its influencing factors, but urban-rural linkages are seldom incorporated in evaluation systems, and geographical factors are rarely recognized as the influencing factors. We construct a URI framework including regional economy, rural development, urban-rural linkage, and urban-rural gap. Based on a dataset consisting of 1,669 counties in China in 2020, we reveal the spatial pattern of URI and find a high correlation between the spatial pattern of URI and the relief degree of land surface (RDLS). Using structural equation modeling, we discover that topography has direct ( − 0.18, p < 0.001) and indirect ( − 0.17, p < 0.001) effects on URI. The indirect negative effects are mediated through the infrastructure, and the combination of localized advantages and modern technical conditions could mitigate the negative impact of topography. Finally, we identify 742 counties as lagging regions in URI, which can be clustered into eight types. Our findings could facilitate policy designing for those countries striving for integrated and sustainable development of urban and rural areas.

Discussion on Structural Health Monitoring of Urban Underground Road Tunnel

The number of urban underground road tunnels in China is increasing year by year,and health monitoring of tunnels is an effective management method to ensure their structural integrity.However,for shorter underground road tunnel projects,insufficient investment often leads to less frequent application of health monitoring systems.The application of intelligent structural health monitoring means can not only reduce the project cost but also help workers fully understand the actual situation of the tunnel structure.Therefore,this paper analyzes the characteristics,problems,and design of the urban underground road tunnel structural health monitoring system,and discusses the implementation of the urban underground road tunnel structural health monitoring system.

On the Fine Structure and the Other Coupling Constants at the Planck Scale

It is shown that the fine structure constant at Planck times tends to one as well as those of the weak and strong interactions. This results by constraining them at the Planck force. That seems to provide interesting new results which confirm that at the beginning of space time (Planck scale) all fundamental forces converge to the same unit value.

Spatial Impact of High-speed Railway on the Urban Scale:An Empirical Analysis from Northeast China

The emergence of rapid transit,primarily represented by high-speed railway(HSR),while reshaping the regional traffic patterns,leads to the reconstruction and redistribution of population and industry.This leads to either shrinkage or expansion of urban scale.However,research on the influence mechanisms of the urban scale has mostly concentrated on historical,economic and social factors.The influence of traffic factors is rarely mentioned in current research.Therefore,this study examines Northeast China,where the change in urban scale is most significant,to discuss the spatial impact of high-speed railway on the urban scale.This is of great significance in terms of enriching current understanding of the factors affecting the urban scale.The results included the following:1)The high-speed railway produced considerable space-time convergence effects,however,simultaneously aggravated the imbalance in traffic development in Northeast China.The increase in accessibility presents attenuation characteristics from the high-speed railway.Additionally,the high-speed railway has changed the mode of cooperation between cities in the provinces,inter-regional and inter-provincial cooperation models gradually become popular.2)The change rate of accessibility and the urban scale present significant spatial coupling phenomena,with the change rate of the Harbin-Dalian trunk lines and its surroundings being more significant.3)There are predominantly four modes of the influence of high-speed railway on the urban scale,which make difference city present expansion or shrinkage.

Physical Mechanism of Formation of the Bimodal Structure in the Meiyu Front System

The bimodal structure of the Meiyu front system is readdressed after Zhou et al.（2005）. The physical mechanism of the formation of the bimodal distribution is discussed. The bimodal structure of the Melyu front system considerably results from atmospheric moisture gradients, though atmospheric temperature gradients are also not negligible. According to the definition of equivalent potential temperature, and by scale analysis, we find that atmospheric equivalent potential temperature gradients, which could be regarded as an indicator of the Meiyu front system, could be mainly attributed to the variations of atmospheric potential temperature gradients with a scaling factor of 1 and moisture gradients multiplied by a scaling factor of an order of about 2.5 × 10^3, which means that small variations of atmospheric moisture gradients could lead to large variations of equivalent potential temperature gradients, and thus large variations of the Meiyu front system. Quantitative diagnostics with a mesoscale simulation data in the vicinity of the Meiyu front system show that moisture gradients contribute to equivalent potential temperature gradients more than potential temperature gradients.

The Structure and Pattern of Urban Network in the Lanzhou-Xining Urban Agglomeration

In this paper,we use factor analysis to evaluate the urban comprehensive quality of each city in the Lanzhou-Xining(Lan-Xi)urban agglomeration.The time distance was obtained by using GIS spatial analysis,and the structure and pattern of the spatial network were analyzed by using the gravity model and social network analysis method.The results show that:1)The scale effect of the Lan-Xi urban agglomeration is gradually emerging,and it is gradually forming the urban agglomeration with Lanzhou and Xining as the core,the Lan-Xi high-speed railway as the axis,and a high-dense connection.2)Lanzhou and Xining are at the core of the Lan-Xi urban agglomeration,which has a strong attraction and spreads to neighboring cities.3)In the network structure of the Lan-Xi urban agglomeration,Lanzhou,Baiyin,Gaolan,Yuzhong,Yongdeng,Dingxi,Lintao,Xining,Ledu,Huangzhong,Ping’an,Minhe and Datong are located in the network core position,which have the superiority position and lead to the entire regional communication enhancement and the regional integration development.4)This urban agglomeration has significant subgroups,eight tertiary subgroups and four secondary subgroup;the tertiary subgroups which compose secondary subgroup have a close connection and mutually influence each other.5)The Lanzhou Metropolitan Area and the Xining Metropolitan Area have an important impact on the surrounding cities,and the peripheral cities are basically controlled by the central city.The Dingxi subgroup,Lintao-Linxia subgroup,Gonghe subgroup have more structural holes than the subgroups within the Lanzhou Metropolitan Area and the Xining Metropolitan Area,so the peripheral cities of these subgroups have relatively less connection with surrounding cities.

Regional Structure and Spatial Morphology Characteristics of Oasis Urban Agglomeration in Arid Area——A Case of Urban Agglomeration in Northern Slope of Tianshan Mountains,Northwest China

It is great important to the health development of urban agglomeration to correctly understand the formation and development law of regional structure of urban agglomeration.Employing the analysis methods like fractal theory and quantitative statistics,coupling with the use of remote sensing images and other spatial data,this article discusses the urban agglomeration of oasis on the northern slope of the Tianshan Mountains in an arid area,and conducts the researches on its city scale,spatial distribution and individual form from 1990 to 2005.The result shows that it has loose hierarchical scale structure and polarization trend of population distribution while its hierarchical scale structure tends to mature.Under the influence of natural conditions,the spatial layout of urban agglomeration of oasis has macro characteristics that suggest cities distributed along oasis edges(dense or sparse),spatially expand along rivers,and cluster around traffic branches.The connectivity among the cities is high and shows an internal organization form of a banding distribution.The whole spatial shape of the internal structure of cities presents a "dumbbell" form,with mononuclear phenomenon receding and multi-nuclear appearing gradually.Individual cities spatially expand along rivers,portraying a long strip appearance.It indicates that the urban agglomeration of oasis shows regular and close structure but with a tendency to be complicated form and the loose structure.In the development of urban agglomeration,the authors recommend that the development of the city with good economic development conditions should be strengthened,and more attention be put into regional planning.

Analysis and Modeling on the Spatial Structure of Urban Land Use: A Case of Jinan, China

Based on the data of urban land use obtained by remote sensing interpretation from aero images in 1986 and 2004, the spatial structure of Jinan is studied in this paper with the method of Geographic Information System (GIS). According to the proportion of land for residence, industry and commerce, the urban district can be distinguished into three rings. Compared with the traditional theory of the ring structure in Western coun- tries, they have many distinctive characteristics. The main func- tions of the inner ring include residence, business and banking, but the proportion of residential land (more than 50%) is considerably higher than that of the cities in Western countries. The land proportion for residence and industry in the intermediate ring is equal on the whole. The main land of the outside ring is for industrial use. From 1986 to 2004, great changes have taken place on the land proportion of different types of use. In the inner ring, the land for residential and industrial use has shrunk much while the land for commercial use has increased. In the intermediate ring, the changes of the three types of land use were not very much and the temporal variation was relatively stable. On the contrary, the structure in the outside ring varies acutely. Though most of it is also for industrial use, the proportion of residential land has in- creased much. The three rings can also be divided into several sectors respectively, according to the function of land use clusters. New trends and mechanisms of the changes of land use impacting the urban structure were proposed in the end of the paper.

Stability of Spatial Structure of Urban Agglomeration in China Based on Central Place Theory

This paper brings forward the concept of stability of the spatial structure of urban agglomeration(UA)based on Central Place Theory by introducing centrality index and fractal theory.Before assessment,K=4 is selected as parameter to calculate centrality index and fractal dimension(K represents the quantitive relationship between city and the counties in Central Place Theory),and then found the number of nodes,the type of spatial structure,the spatial allocation of nodes with different hierarchy affecting the stability of spatial structure.According to spatial contact direction and the level of stability,UAs in China are classified into five types.Finally,it is posed as a further question that how to use hierarchical relation K=6 and K=7 in central place system to coordinate with the assessment of stability of soatial structure is brought forward.

Analysis and forecasts of investment scale and structure in upstream sector for oil companies based on system dynamics

Oil and gas exploration and production is the most important and key segment in the whole business chain of the petroleum industry.Therefore,oil companies always put much emphasis on making scientific and reasonable decisions about investment scale and structure in the upstream sector,so that they can minimise business risks and obtain high returns.According to the system dynamics theories and methods and based on the actual results from an oil company＇s practice in China,a system dynamics model is built in this paper for analyzing and forecasting the upstream investment scale and structure for an oil company.This model was used to analyze the investment effect of a large oil company in China, and the results showed that the total upstream investment scale will decline slowly in a short period and the investment proportion of different parts should be adjusted if some influencing factors are taken into account.This application practice was compared with the actual data and indicated that the system dynamics（SD） model presented in this paper is a useful tool for analyzing and forecasting of upstream investment scale and structure of oil companies in their investment decisions.