Fractal cities and city fractals have been studied for about 30 years, but many basic problems have not yet been fully solved. Among the various basic fractal problems about cities, the most important are how to estimate fractal dimension and how to identify fractal nature of a city as a system or a system of cities in an effective way. Based on urban form and the box-counting method, this article discusses the approaches to calculating fractal dimension and determining fractal property of cities. The theoretical foundation of fractal dimension computation is the concept of perfect covering. In other words, in the process of fractal dimension measurement, a fractal object should be covered with boxes in the best way: nothing more, nothing less. In practice, it is hard to find the optimal way of box covering. Therefore, three rules should be followed. First, the sequence of measuring scales should be consistent with the cascade structure of a fractal city so that the fractal details can be captured in a reasonable way. Second, the operation of obtaining observational data should be simple and convenient to use so that the method can be applied by beginners. Third, the size of the dataset for fractal dimension estimation should be large enough so that the result of fractal parameters is stable. A conclusion can be reached that the geometric scale rather than the arithmetic scale should be employed to make a measurement because the fractal structure can be abstracted as geometric sequences instead of arithmetic sequences, and the measuring scale sequence should comply with the 1/2n rule (that is, 1, 1/2, 1/4, …). After estimating the fractal dimension of a city, the fractal property can be identified by the statistics from fractal dimension calculation. The good way of identifying the fractal nature of urban form is to use confidence statement, which consists of fractal dimension values, margin of error, and level of confidence. Given a level of significance (for example, α=0.05), we can draw an inference that a city's form is of fractal structure because it has a fractal dimension with a determinate level of confidence (for example, (1-α)×100%=95%). Using statistical analysis, however, one can never have full (100%) assurance that a city has a fractal form.
Urban physical space upgrading is a natural historical process of urban development. Upgrading urban physical space is an inevitable and common practice. In Chinese cities that undergo great transition, the extent and scope of development in inner cities are gradually increasing, which have important implications for the restructuring of the socioeconomic aspects of cities. This article first presents a comprehensive summary of the theories and research on the upgrading of urban physical space within China and internationally, extracts core ideas and evaluation methods concerning the background, succession, models, and strategies for urban physical space upgrading, and summarizes the successful practices and experiences of urban physical space upgrading. Second, the article examines the prospects of research on urban physical space upgrading in China with respect to the determination and spatiotemporal organization, building assets demolition losses, upgrading model and comprehensive assessment, influencing factors, and quantitative research mechanisms. Finally, the paper argues that under the background of new urbanization and developing a resource-saving society, it is necessary to strengthen the systematic, comprehensive, dynamic, and quantitative research of Chinese urban physical space upgrading in order to provide a basis for the optimization of control policies and plans that take into consideration local conditions.
This study examines changes in form and marginalization of the rural residential land in China under the background of urban-rural transformation development. We first defined the concept and essence of marginalization of rural residential land, then discussed its main characteristics and developed the diagnostic criteria. Marginalization of rural residential land is a gradual process, in which the existing housing security function of such land is weakening, declining, or being replaced by other uses under an existing land use and socioeconomic structure. Meanwhile, farmers' response behavior will result in significant changes in rural residential land in terms of land use intensity, conversion, and management system. Utilization rate, area ratio of self-occupancy, and cost of use are three main indices to diagnose the marginalization of rural residential land. Generally, decline of the utilization rate is an important indicator of explicit marginalization of rural residential land. Under multifunctional use, a gradual decrease of the self-occupancy area ratio indicates an implicit marginalization. An increase of the use cost of current land use is a reliable evidence for predicting the trend of marginalization. The discussion on the characteristics of the marginalization of rural residential land and its diagnostic criteria will provide a new research perspective for the changes in the form and function of rural residential land.
Unequal allocation of resources is the core problem in the development of China's basic education system, spatially reflected as uneven distributions. Spatial allocation of basic education resources, which is closely related to people's livelihood, social justice, and healthy urbanization of China, has become the research hotspot of many disciplines such as education, economics, sociology, geography, and urban planning. In order to promote research development and application of the subject, this article reviews the development of Chinese research on the distribution of basic education resources and divides it into three stages: exploration stage, deepening stage, and rapid expansion stage. It summarizes the achievements and analyzes the deficiencies of the four major research contents with regard to basic education resources distribution: the characteristics of layout and change in regions and urban and rural areas; the supply and demand factors that influence distribution, including the distribution of school-age population, technical standards of planning, ability and principles of local government's resource allocation that are controlled by education financing system and education policies; the standards and methods of evaluation for spatial equilibrium based on efficiency and fairness; and the effects on population mobility, residential differentiation, and traffic structure change in urban and rural areas. Over the past decade, Chinese studies on the distribution of basic education resources have made great progress, especially in improving models of accessibility analysis and measuring and evaluating resource distribution. However, some problems still exist. Disciplinary integration is inadequate. The current research on spatial features, whose main function is to serve for layout evaluation, lacks analysis on structure and modes. Mechanism investigation based on local characteristics is insufficient. Above all, interdisciplinary methods and techniques should be used in future studies. Long-term follow-up research and systematic analysis based on case studies, political and economic background and influence, regular patterns of spatial structure and change, and the formation mechanism for spatial change by multi-factor integrated impact should receive more attention in studies on resource distribution of basic education.
In recent years, the cruise industry has become one of the most dynamic, rapidly developing and profitable segments in the global tourism and hospitality industry, with millions of passengers each year. China has become one of the most attractive emerging markets in the Asia-Pacific region. Cruise tourism has significant economic impacts on port cities and relevant tourism regions, outputting remarkable employment opportunities and total revenue. However, the development of the cruising sector also brings negative economic, environmental, and social and cultural impacts on cruise destinations and local communities. With the fast development of the Chinese cruise industry, influences of cruise tourism will become far-reaching. It is critical for the Chinese cruise industry to better understand impacts of cruise tourism, particularly the negative side. However, this issue is neglected by the Chinese academic community. Using a sustainable and responsible tourism lens, the purpose of the current article is to systematically examine the negative impacts of cruise tourism by comprehensively reviewing international studies in relation to externalities of cruise tourism. Accordingly, a model or framework of responsible cruise tourism, consisting of governments, non-profit organizations, local communities, cruise passengers, and the cruise industry, is proposed. This article is an attempt to stimulate more attentions from Chinese researchers to the sustainability and responsibility of cruise tourism.
Through the comparative study of the correlations between the normalized difference vegetation index (NDVI), normalized difference moisture index (NDMI) and land surface temperature (LST), the suitability to research LST using NDVI and NDMI was verified. Based on Landsat 8 remote sensing imagery in the Zhengzhou-Kaifeng metropolitan area, LST was retrieved, and both NDVI and NDMI were calculated. At the overall, regional, and pixel levels, the correlations between LST and NDVI, NDMI were analyzed. Using GEO-Da, the spatial correlations between LST and NDVI, NDMI were simulated with the data of three sampling intervals of 150 m, 300 m and 450 m. The conclusions are as follows. First, there is a stronger linear negative correlation between LST and NDMI, and sectional analysis shows that NDMI resembles a mirror image of LST, whereas the correlation between LST and NDVI is much weaker. Second, buffer analysis shows that with the increase of distance from the down town and increase of the number of land use types, the correlation between NDMI and LST also increases gradually. Third, in the analysis of Moran's I spatial correlation, the negative correlations between LST and the two indices were significant, but because of the great difference between the values of water body in the two indices, NDMI and LST show stronger negative correlation, while the correlation between NDVI and LST is relatively weak. In general, compared with NDVI, NDMI is more suitable as an effective indicator for quantitative analysis of LST.
：Lake water clarity is an important parameter of lake water property, which is an integrated response of lake plankton and organic and inorganic solutions, and has significant scientific and practical implications for lake ecological condition research. Remote sensing is a key method for obtaining lake clarity in wide areas and within long time spans. On the Tibetan Plateau, there are more than 389 lakes with area greater than 10 km2, making the Plateau an ideal region for environmental and climate change research. However, study on the estimation of lake water clarity on the Tibetan Plateau by satellite data is insufficient at present due to the paucity of in situ lake water clarity measurement data. In this study, retrieval models of lake water clarity were established based on the in situ water clarity measurements of 24 lakes distributed in different areas on the Tibetan Plateau and the corresponding MODIS imageries. Statistical methods including linear, exponential, power function, and logarithm regressions were used to build relationships between lake water clarity and the reflectance of MODIS bands on the Tibetan Plateau. The results show that power function model with MODIS green band B4 as single independent variable is the best model for estimating lake water clarity (SD value) on the Plateau (R2=0.91, N=24). The stability of the model was also tested based on 10 in situ SD data at different times in a single lake. Based on this model, we analyzed the temporal variation of lake water clarity of a typical lake Tangra Yumco as an example. The result demonstrates clear seasonal and inter-annual variations of lake water clarity for this lake. Preliminary analysis indicates that the variation of water clarity in precipitation-meltwater rich season is correlated with precipitation intensity of the basin. Our work proved that the reflectance of remote sensing imageries is valid for estimating lake water clarity on the Tibetan Plateau. This may promote further investigation of lake water clarity and its influencing factors on the Tibetan Plateau.
Tanzania is an important part of China's 'the Belt and Road' strategy, and China has become the largest trade partner of Tanzania. For the extensive cooperation in infrastructure, housing and public services, spatial pattern of population in Tanzania aroused broad attention. Based on the national census and regional statistics data of Tanzania, population density analysis, distribution concentration index, gravity center model, and population growth shift model were used to analyze Tanzania's population spatial distribution pattern and evolution since its economic reform in the late 1980s. The results shows that: (1) Divided by the central railway line, the population of Tanzania showed a characteristic of sparse distribution in the south and dense distribution in the north; (2) There was a growing trend of uneven population distribution during the period of 1988-2012. The population gravity center was always in the central-north region and had a tendency to continue to move northward; (3) Population movement to urban areas was the major process of population redistribution. The capacity of core cities in attracting migrants was growing. The Dar Es Salaam region experienced most rapid population growth that led to significant negative population growth shift in its surrounding areas; (4) Infrastructure such as railways and ports had evident effect on population agglomeration.
Food security is a key governmental and academic concern in China. In the past 25 years, due to the rapid industrialization and urbanization, competition for land resources and environmental pollution threatened the sustainability of China's grain production. Studies to date have focused on the urbanized areas, and rural industrial land expansion and impact on food security in China remain largely unknown. This study constructed an 1 km resolution grain output dataset using the latest remote sensing data-derived land use dataset (NLUD-China) and county-level grain production data of China to evaluate the impacts of industrial land expansion and pollution on food security of the country. The results show that the industrial land area increased by 326% between 1990 and 2015, with an increasing expansion rate of 288 km2/a in the 1990s to 2600 km2/a in 2010-2015, close to the current urban expansion rate (3000 km2/a). During 1990-2015, industrial land expansion led to 1.7×104 km2 reduction of crop land, resulting in a direct production loss of 6.49 Mt (106 tons). Indirect losses caused by industrial pollution was conservatively estimated at 83.20 Mt. Overall estimated losses due to industrial land influence can be up to 17% of China's cropland production. Spatially, direct loss of crop production in China decreased from the central and coastal region to the northwest region. In the central and western regions losses caused by soil pollution is relatively serious. With the increasing population and other socioeconomic and environmental changes, the balance between the supply and demand of food becomes more delicate. Therefore, remote sensing monitoring of crop land and industrial land for national macroeconomic development and environmental protection is of great significance.
Fuzhou City is an important gateway west of the South China Sea. This study uses geographically weighted regression (GWR) as the transformation rules of cellular automata (CA) layer based on the multi-level constraint conditions, taking into account geographical location, natural factors, and the multi-criteria and willingness of various agents to make decisions on environmental change, to simulate urban land expansion of Fuzhou City from 2000 to 2015. Using the urban land use data derived from remote sensing imageries of Fuzhou City in 2000-2015 as a reference, and with the help of GIS spatial analysis technology, this study developed an improved model of urban land expansion based on coupled CA and ABM. The traditional and improved CA-ABM models were used to simulate urban land expansion and change with a microscopic view for Fuzhou City in 2000, 2005, 2010, and 2015 from multiple angles and at multiple levels. The results show that the overall accuracy of the traditional and improved CA-ABM models was higher than 80%, and the simulation results based on the CA-ABM models for Fuzhou City are reliable. The point-to-point overall accuracy and Kappa of the improved CA-ABM model were higher than the traditional CA-ABM model, and the results of the improved CA-ABM model were closer to the actual distribution of urban land expansion in Fuzhou. It indicates that the improved CA-ABM model can be used to simulate urban land expansion, more accurately expresses a variety of geographic processes and mechanisms, and improves the reliability and stability of the simulation results. Finally, a forecast of the distribution of urban land expansion in 2020 and 2030 based on the improved CA-ABM model with scenario natural, economic, and social developments in Fuzhou provides an important theoretical and technical support for the urban land use planning of the city.
：Business activities conducted in office buildings are becoming the main driving force of economic development in metropolitan areas. Research on the external environment of office space not only can provide some guidance for office space planning and design, but also can improve the quality of urban built environment and urban construction. This study took the 10 typical office clusters in Beijing as the survey areas and selected safety, accessibility, comfort, and convenience as the key aspects of evaluation to analyze resident satisfaction toward the external environment of office space in Beijing. The main conclusions are as follows. (1) The overall subjective evaluation result of external environment of office space is satisfactory. Compared with the high satisfaction level of safety, rail transit and office supporting service network developments lagged behind, which led to a low degree of comfort and convenience. (2) Individual characteristics including gender, age, level of education, and position have important impacts on the perception of the external environment of office clusters. Women demand higher safety. People with higher education level and position have higher demand for better external environment. (3) According to the evaluation result, the 10 office clusters in Beijing can be divided into four categories: mature advanced type, to be improved type, lagged behind type, and uncoordinated type. The evaluation results of office clusters reveal the difference between the actual external environment of the office space and the psychological needs of office employees, which provides a basis for differentiated improvement of such environments.
Through a case study of typical online travel notes, this research found that the vertical development of tourists' self-concept has three essential features. First, in the temporal dimension, tourists' self-concept is a dynamic and cyclic process. As time goes on, tourists' self-concept experiences diachronic changes of the actual self, ideal self, and social self. Changes include that the actual self goes through "weariness-identity-appreciation"; ideal self goes through "eagerness-freedom-satisfaction"; and social self goes through "alienation-authenticity-responsibility." This process is dynamic, and will be replaced by new experiences. Second, when the spatial dimension is concerned, the tourists experience the change of life-world and tourism-world, tourists' self-concept experiences "life-world self-diagnosis-tourism- world self-reflection-life-world self-reconstruction. Last but not the least, travel is a non-material and transforming process. Instead of visiting material objects, tourists also involve in subject's cognitive process, including self-discovery, self-reflection, self-identity, and self-reconstruction.
