城市职能特征及其形成机理研究进展与展望

城市职能是城市定位、制定发展战略的重要依据,城市职能具有阶段性、等级性、地域性等特征,论文通过对不同学者的相关研究成果进行归纳总结,以期把握城市职能特征及其形成机理的普遍性规律。结果表明：① 不同城市发展阶段的职能特征表现为城市主导职能不断更替,农业社会阶段主要是政治和商业职能,工业社会阶段主要是制造业、商贸和物流职能,后工业化阶段是服务业职能且以生产性服务业职能为主。② 不同城市规模等级的职能特征表现为城市等级越高,城市职能综合性越强,服务业职能越强。③ 不同空间层面城市职能特征表现为,全球层面,发达国家本土通过城市职能升级,全球产业转移,形成以服务业为主导职能,发展中国家通过承接制造业转移,加速工业化,形成工业职能为主导职能,服务业职能地位不断提升;全国层面,城市职能地带性差异较大,东部工业职能依然突出,西部矿业职能、科技职能、行政职能较明显;城市群层面,世界发育成熟的城市群,在区域中心城市与外围城市之间,以及外围城市之间已经形成紧密的联系和职能分工。中国的许多城市群在中心和外围城市之间也具有明确的职能分工,中心城市以服务业职能为主,但外围城市之间职能分工还不明确。④ 城市职能演变影响因素方面,自然条件、人口、交通、政府引导、区位等传统因素起基础作用,科技、全球化、信息化等新因素作用越来越大。城市职能演变还受区域分工、产业升级、产业转移、趋同发展等机制共同作用。⑤ 未来研究方面,研究时间上应补充完善长时间尺度和近期研究的城市职能研究,研究内容上应加深城市职能效应、城市职能演变机制和职能优化方面的研究,与国家战略进行融合;研究方法上除了统计分析,还可采用调研、问卷、访谈等方法进行补充。     

The Evaluation of Urban Green Space Landscape Changes and Ecosystem Services in Beijing

As a very important part of the urban ecosystem, the urban green space system plays an active role in maintaining the urban ecosystem stability, providing ecosystem services, and improving the quality of the urban environment. In order to deal with the problems brought about by the deterioration of the urban ecological environment, it is necessary to study and analyze the spatial distribution pattern, evolutionary characteristics and ecosystem services of urban green space to maximize its ecological benefits and comprehensive functions. In this study, we took Beijing urban area as an example, and based on the spatial distribution data of urban green space and remote sensing data, we first calculated the urban green space type transition matrix, landscape pattern index and ecosystem services. Then, we analyzed the changes in urban green space landscape patterns, ecosystem services and their spatial distributions from 2000 to 2020, and studied the interactive relationships between landscape changes and changes in ecosystem services. The results showed three key findings. (1) Beijing’s urban green space construction has achieved remarkable results from 2000 to 2020. The area of green space has increased by 77.41%, mainly from cultivated land and construction land. (2) From 2000 to 2020, the amounts of dust retention, SO₂ absorption, NO₂ absorption, cooling and humidification, carbon fixation and oxygen release, and rainwater runoff reduction in Beijing's urban green space have shown continuous increases in general. (3) There is a close relationship between urban green space landscape changes and green space ecosystem services, and total area (TA) has the highest correlation with ecosystem services. Except for rainwater runoff reduction, the correlation coefficients between TA and ecosystem services are all higher than 0.85. This research can provide theoretical guidance for optimizing Beijing's green space and determining how to maximize the effect of green space for improving the ecological environment, and ultimately provide a scientific basis for the construction of Beijing's ecological environment.     

A continued fraction approach to the inverse problem of electrical conductivity

Summary. The problem of determination of the electrical conductivity of the Earth from the geomagnetic induction data is formulated as that of finding the coefficients of the continued fraction expansion of a certain rational fraction representation of the total response (or impedance) of the medium at the surface when this quantity is given for N frequencies. The coefficients of expansion are related to the conductivities of N layers of constant attenuation, where, within each layer the conductivity is assumed to be constant. Thus in this approach the conductivity profile resulting from the inversion of the response function is given as a series of step functions.     

Seismic reflection and transmission coefficients of a self-similar interface

The derivation of seismic reflection and transmission coefficients is generally based on the assumption that the medium parameters behave as step functions of depth, at least in a finite region around the interface. However, outliers observed in well logs generally behave quite differently from step functions. In this paper we represent an interface by a self-similar singularity, embedded between two homogeneous half-spaces, and we derive its frequency-dependent normal-incidence reflection and transmission coefficients. For ω  → 0 the expressions for the coefficients reduce to those for a discrete boundary between two homogeneous half-spaces; for ω → ∞ they become frequency-independent. These asymptotic expressions have a relatively simple form and depend on the singularity exponent α .
  The exact as well as the asymptotic expressions are used to evaluate the time-domain reflection and transmission responses of a self-similar interface. Finally, we use a numerical method to model the response of a smoothed version of a self-similar interface (note that the velocity of a smoothed singularity remains finite). It turns out that smoothing has hardly any effect on the response, provided that the smoothing does not affect the scales corresponding to the seismic frequency range.     

Heterogeneous structure around the Jemez volcanic field, New Mexico, USA, as inferred from the envelope inversion of active-experiment seismic data

We analyse active-experiment seismic data obtained by the 1993 Jemez Tomography Experiment (JTEX) programme to elucidate the heterogeneous structure of the Jemez volcanic field, which is located at the boundary between the Colorado Plateau and the Rio Grande Rift. Using a single isotropic scattering assumption, we first calculate the envelope Green's functions for the upper and lower crust and the uppermost mantle. By fitting the theoretical envelopes with the observed three-component data, we estimate depth-dependent features of the scattering coefficients around Valles Caldera. We estimate the ratios of scattering coefficients, rather than scattering coefficients themselves, because of the uncertainty of the seismic efficiency of the explosive sources and knowledge of absolute site-amplification factors. The strongest scattering coefficients are observed at a shallow depth beneath the Valles Caldera. This is considered to be related to the complex structure caused by two episodes of caldera formation and the ensuing resurgent uplift in the caldera, etc. The depth-dependent characters of the scattering coefficients for the Colorado Plateau and the Rio Grande Rift are similar to each other: a transparent upper crust and a heterogeneous lower crust (small and large scattering coefficients, respectively). However, the scattering coefficients beneath the Rio Grande Rift are several times larger than those beneath the Colorado Plateau. Depths of the lower crust and the Moho boundary beneath the Rio Grande Rift are shallower than those of the Colorado Plateau. From their geological settings and other geophysical results around the region, we infer that the larger scattering coefficients of the rift are associated with rift formation and volcanic activity, such as magma ascent from the upper mantle to the crust.     

盐田卤水自动监测系统软件的开发

本文系统地介绍了盐田卤水自动监测系统软件的设计过程、组织结构、功能和用途。该软件采用ＷＩＮＤＯＷＳ９５的多线程技术,实现对盐田监测参数（温度、密度、钾含量等）的全天２４小时监测,并可根据实际需要将某些时间的监测数据保存到数据库中。     

城郊土地利用功能演变——以贵州省惠水县乡村旅游度假区好花红村为例

论文以贵州省惠水县乡村旅游度假区好花红村为典型案例,运用空间分析方法,利用高分辨率遥感影像和实地调查访问数据,分析了2006—2019年好花红村土地利用功能演变规律,探讨了土地利用功能转型助推乡村振兴的作用。结果表明：① 好花红村土地利用功能受土地利用转型的影响,由传统单一的农业生产功能、社会保障功能和生态保育功能转变为复合型观光休闲功能和经济发展功能,增加了经济效益的同时保证了生态效益,土地利用功能总体上呈现出多元化和复合化特征;② 研究区不同演变阶段的演变模式存在显著差异,经历了单一农业生产功能阶段、多元功能转型过渡阶段、多功能复合转型阶段,土地利用功能演变有以农为主、乡村旅游为辅,农旅结合、农业逐步退缩,以乡村旅游为主、整体转型3种模式;③ 自然条件是土地利用功能变化的基础动力,经营主体变化是土地利用功能转型的内在动力,区域发展政策是驱动土地利用功能多元化的根本动力,旅游市场“规模化”需求是驱动乡村功能和土地利用功能转化的重要推动力,这些因素相互作用,共同驱动土地利用功能演变。     

Monthly calibration and optimization of ?ngstr?m-Prescott equation coefficients for comprehensive agricultural divisions in China

?ngstr?m-Prescott equation (AP) is the algorithm recommended by the Food and Agriculture Organization (FAO) of the United Nations for calculating the surface solar radiation (R_s) to support the estimation of crop evapotranspiration.Thus,the a_s and b_s coefficients in the AP are vital.This study aims to obtain coefficients a_s and b_s in the AP,which are optimized for China’s comprehensive agricultural divisions.The average monthly solar radiation and relative sunshine duration data at 121 stations from 1957–2016 were collected.Using data from 1957 to 2010,we calculated the monthly a_s and b_s coefficients for each subregion by least-squares regression.Then,taking the observation values of R_s from 2011 to 2016 as the true values,we estimated and compared the relative accuracy of R_s calculated using the regression values of coefficients a_s and b_s and that calculated with the FAO recommended coefficients.The monthly coefficients,a_s and b_s,of each subregion are significantly different,both temporally and spatially,from the FAO recommended coefficients.The relative error range (0–54%) of R_s calculated via the regression values of the a_s and b_s coefficients is better than the relative error range (0–77%) of R_s calculated using the FAO suggested coefficients.The station-mean relative error was reduced by 1%to 6%.However,the regression values of the a_s and b_s coefficients performed worse in certain months and agricultural subregions during verification.Therefore,we selected the a_s and b_s coefficients with the minimum R_(s )estimation error as the final coefficients and constructed a coefficient recommendation table for 36 agricultural production and management subregions in China.These coefficient recommendations enrich the case study of coefficient calibration for the AP in China and can improve the accuracy of calculating R_s and crop evapotranspiration based on existing data.     

Reduction of disparities in access to green spaces: Their geographic insertion and recreational functions matter

Green spaces (GS) have many functions that can moderate the climate change impact and help prevent disease and thus alleviate public health expenses in a context of aging societies. However, several socioeconomic, demographic and geographic processes may render the access to GS challenging. Moreover, it is often critical to know what type of GS service to develop at a specific place. Also, measurements accuracy issues could be critical for planning and decision making. As an example of what could happen in many other cities of different sizes, we modeled and compared the access to GS, including several of their specific functions, in the Census Metropolitan Areas (CMA) of Montreal and Quebec City in Canada. We used the Quebec Integrated Chronic Disease Surveillance System (QICDSS) (average of 3 million people per year over 1996–2011) to measure over time, the proximity of each individual to the closest GS boundary using travel costs and spatial interaction models. ANOVA models and their corresponding base regressions were used to evaluate the statistical significance of the relationship of GS distances and surface to density, deprivation, gender and age, including interaction terms. The spatial clustering of the reduction of distances to GS was evaluated on a chronological basis. Unlike the larger CMA of Montreal, Québec City CMA showed greater equity in access to GS, largely due to the specific geographic insertion of linear GS. The CMA of Montreal showed an improvement in the access to GS which benefits the wealthy in the densest areas on the island of Montreal. Everything happens as if a green gentrification process affects the access to GS in Montreal. Our results suggest that for the promotion of GS as an important element of primary prevention in public health, both the quality or functions of GS and the geographic determinants of their access are of higher importance than a simple consideration of total GS surface per capita as often used by decision makers or public health promoters. They also underline the limits of standard measurements of attraction and accessibility and the complexity for large cities to promote environmental justice, given the complexity of their socio-demographic processes.     

Wavelet modelling of broad-band receiver functions

We present a wavelet modelling approach to invert for S -wave velocities from broad-band receiver functions. Taking spline function as the basic wavelet, the broad-band receiver function is decomposed into five resolution scales by Mallat's pyramid algorithm. The linearized least-squares inversion procedure is applied to every resolution scale. The fifth-scale approximation of receiver function is first inverted to recover the slowly varying background velocity variations with respect to a reference model. This solution is then taken as the initial model for fitting the fourth-scale wavelet coefficients of receiver function to further tune the solution to resolve sharper variations. This procedure is iteratively carried out up to the first-scale wavelet coefficients of receiver function. In this manner, the model neighbourhood containing the global minimum is first searched from the coarsest-scale receiver function, and the search gradually focuses on the global minimum by introducing finer-scale information of receiver function. Noise-free synthetic receiver function tests show that wavelet modelling of receiver functions can guide a certain range of initial models to converge to the true velocity distribution. Tests on actual data indicate that wavelet modelling can provide results very similar to those inferred by joint inversion of receiver function and surface wave dispersion.     

Mean slope-angle frequency distribution and size frequency distribution of landslide masses in Higashikubiki area, Japan

Landslide mass size frequency distributions and mean slope-angle frequency distributions were calculated for slump, slide, and creep type landslides in the Higashikubiki area. Mean slope-angle frequency distributions closely approximated Weibull distributions. Size frequency distributions show power-law dependencies. Both can be explained by modeling landslides as linked uniform blocks in tensile force. Power coefficients for size frequency distributions were 2.01–2.32 (approximation to power functions) or 2.10–2.24 (approximation to Pareto distributions).     

中国城市生产、生活、生态空间质量水平格局与相关因素分析

城市作为人口集聚和社会经济活动的主要载体,也是生产、生活、生态空间的矛盾集中地。本文在城市“三生”空间优化理论框架指导下,构建了城市“三生”空间优化评估指标体系与评估模型,分析2015年中国289个地级及以上城市的“三生”空间质量水平的总体特征和空间分布规律。结果表明：城市“三生”空间质量指数总体处于较低水平,空间格局上从东南沿海向西部和东北地区递减;东北地区的生产空间质量塌陷尤为明显,西部地区生活空间质量堪忧,生态空间质量则与地方的自然生态条件和污染治理相关;生产和生活空间优化之间相辅相成,但不乏城市生产和生态空间质量反差较大;“三生”空间质量水平与人口规模、行政等级之间呈倒U型相关,即规模在1000万~1500万间的城市更利于实现“三生”空间优化,城市“三生”空间质量水平与人均GDP正向相关,职能综合城市和城市群地区城市“三生”空间质量水平更高。     

Configuring the neighbourhood effect in irregular cellular automata based models

Cellular automata (CA) models have been widely employed to simulate urban growth and land use change. In order to represent urban space more realistically, new approaches to CA models have explored the use of vector data instead of traditional regular grids. However, the use of irregular CA-based models brings new challenges as well as opportunities. The most strongly affected factor when using an irregular space is neighbourhood. Although neighbourhood definition in an irregular environment has been reported in the literature, the question of how to model the neighbourhood effect remains largely unexplored. In order to shed light on this question, this paper proposed the use of spatial metrics to characterise and measure the neighbourhood effect in irregular CA-based models. These metrics, originally developed for raster environments, namely the enrichment factor and the neighbourhood index, were adapted and applied in the irregular space employed by the model. Using the results of these metrics, distance-decay functions were calculated to reproduce the push-and-pull effect between the simulated land uses. The outcomes of a total of 55 simulations (5 sets of different distance functions and 11 different neighbourhood definition distances) were compared with observed changes in the study area during the calibration period. Our results demonstrate that the proposed methodology improves the outcomes of the urban growth simulation model tested and could be applied to other irregular CA-based models.     

Monuments and their functions in urban public space

ABSTRACT

The aim of the article is to present and discuss functions of public monuments in relation to different dimensions of geographical space. The authors discuss public spaces, monuments, public art, based on a mixed-method approach and an analysis of scientific literature as the main research method. The theoretical discussion is supplemented with the results of Internet searches and an analysis of media supplements, and specific examples are given, including some from Poland. An additional method was autoethnography, which involved an analysis of cultural phenomena based on the authors’ experience. The analysis revealed that monuments were part of public art and thus enriched public spaces in cities. They fulfilled different important functions: artistic, symbolic, commemorative, political, social, religious, marketing, and mixed. Additionally, the monuments reflected the contemporary transformation of ideas and social orders and therefore also reflected contemporary urban debates. They were products of social relations, powers, ideas, identities, and the collective memory reflected in the urban spatial structure of cities. The authors conclude that the examples presented in the demonstrate that monuments perform various functions in urban public spaces. From a spatial perspective, the role of monuments depends on their different impacts on people’s perceptions and interpretations of space.     

Integrating spatial and temporal contexts into a factorization model for POI recommendation

Matrix factorization is one of the most popular methods in recommendation systems. However, it faces two challenges related to the check-in data in point of interest (POI) recommendation: data scarcity and implicit feedback. To solve these problems, we propose a Feature-Space Separated Factorization Model (FSS-FM) in this paper. The model represents the POI feature spaces as separate slices, each of which represents a type of feature. Thus, spatial and temporal information and other contexts can be easily added to compensate for scarce data. Moreover, two commonly used objective functions for the factorization model, the weighted least squares and pairwise ranking functions, are combined to construct a hybrid optimization function. Extensive experiments are conducted on two real-life data sets: Gowalla and Foursquare, and the results are compared with those of baseline methods to evaluate the model. The results suggest that the FSS-FM performs better than state-of-the-art methods in terms of precision and recall on both data sets. The model with separate feature spaces can improve the performance of recommendation. The inclusion of spatial and temporal contexts further leverages the performance, and the spatial context is more influential than the temporal context. In addition, the capacity of hybrid optimization in improving POI recommendation is demonstrated.     

江苏省土地利用功能变化及其空间格局特征

面对资源约束与生态环境破坏的双重压力以及经济发展与社会稳定的双重需要,优化国土空间开发格局已成为中国经济社会可持续发展的重要任务。土地利用作为国土空间开发的核心载体,研究其利用过程中形成的各项功能效应及其变化特征,有利于摸清国土空间开发中的症结与问题。以江苏省为实证,立足区域国土空间发展目标,构建包含农业生产、城镇生活、生态维护等3项一级功能以及9项二级功能的土地利用功能分类体系,以1 km×1 km空间格网为评价单元,运用经济社会数据空间化方法以及InVEST、RUSLE等模型方法,综合测度2000年和2015年两个时间断面下江苏省各项土地利用功能及其变化,分析土地利用功能变化特征,总结土地利用功能变化模式及成因,并划分功能变化分区。结果表明：① 2000-2015年,江苏省农业生产功能西增东减;南部地区城镇生活功能增强明显高于中北部地区;各项生态维护功能变化特征差异显著。② 江苏省农业生产功能与生态维护功能变化存在协同关系,与城镇生活功能变化存在权衡关系。③ 江苏省土地利用功能变化可划分为西南丘陵综合功能提升区、太湖平原生产功能减弱区、沿江平原生活功能增强区等8个类型区,各分区功能变化主导模式存在差异。     

An alternative method for calculation of Rayleigh and Love wave phase velocities by using three-component records on a single circular array without a central station

A method for the computation of phase velocities of surface waves from microtremor waveforms is shown. The technique starts from simultaneous three-component records obtained in a circular array without a central station. Then, Fourier spectra of vertical, radial and tangential components of motion are calculated for each station and considered as complex-valuated functions of the azimuthal coordinate. A couple of intermediate real physical quantities, B and C , can be defined from the 0- and ±1-order coefficients of the Fourier series expansion of such functions. Finally, phase velocities of Rayleigh and Love waves can be retrieved from B and C by solving respective one-unknown equations. The basic assumption is the possibility of expanding the wavefield as a sum of plane surface waves with Rayleigh and Love wavenumbers being univocal functions of the circular frequency. The method is tested in synthetic ambient noise wavefields confirming its reliability and robustness for passive seismic surveying.     

Types of Public Spaces: The Polish Contribution to the Discussion of Suburban Public Space

Intensive suburbanization, especially in postsocialist countries, and a deficiency of fully public spaces result in an increasingly complex mixture of different types of spaces of public functions. Where there is a deficiency of completely public spaces, their role can be enhanced by those places available to the public for a specified period of time and under certain circumstances. Such places are provided and maintained not only by the public but also by the private sector. This article explores the diversity of places of public character and looks for criteria that organize this diversity. It introduces a new typology that corresponds mainly to the suburbs and combines five criteria of categorization: intended users, time limits as to access, prevailing form of control, intended functions, and visual characteristics. The typology draws attention to the role of spaces not intended for all the public but for selected groups and that of spaces with time-limited access. Such semipublic places are consistent with the lifestyle of suburbanites and therefore play an increasingly important role in suburban social life.     

国土空间规划:产业空间配置类单幅总图的研制

省级空间规划中的产业空间配置是在“三区三线”划分基础上进一步明确地域功能、引导地域功能格局优化的必要步骤。在综合考虑方法的创新性和成熟度基础上,对在“三区三线”格局内进行产业空间配置的逻辑架构、技术方法、数据体系等内容进行定量和定性相结合的探索性分析,形成了主导产业筛选、产业园区适宜规模识别、重点产业空间识别等流程体系,共同合成了一套用以研制空间规划中的产业空间配置类单幅总图的技术方法。其中,在主导产业筛选体系中综合考虑了产业关联、产业发展基础、发展潜力和政策支持等方面,在产业园区适宜规模识别体系中综合考虑了产业园区级别、园区产业是否切合区域产业发展导向、园区产业发展程度、与各类红线及城镇的空间关系等指标,并从微观企业入手向上总结重点产业空间范围,结合“三区三线”的国土空间适宜性、城镇空间划分结果进行空间叠加,做到了对省级重点产业空间的有效识别和落地。同时,以福建省为案例进行了实践分析。     

The inverse problem for heat flow data in the presence of thermal conductivity variations

Summary. We demonstrate a method of performing linear programming optimizations of functionals of subsurface temperature, when thermal conductivity is a known piecewise-constant function. Data comprise heat flow measurements on the flat isothermal surface of this structure, within which heat transfer is by steady-state conduction. Two-dimensionality is assumed. The approach involves establishing constraints which demand the continuity of temperature and the normal component of heat flow across all internal boundaries. These unknown functions are expanded as truncated Fourier series whose coefficients become unknowns of the linear programming solution vector; linear relations are established between these coefficients which guarantee harmonicity of temperature in each region of uniform conductivity, as well as the continuity requirements. Variations of the formalism are detailed for three simple types of geometry. As an example the method is applied to a heat flow data set from Sass, Killeen & Mustonen over the Quirke Lake Syncline of Ontario, Canada.