Urban planning in Tanzania has focused mainly on economic development. The Tanzanian government prioritizes large-scale modern projects to increase national income and propel world-class urban settlements. Dar es Salaam, Tanzania's largest city and main commercial center has experienced remarkable urban development. Unfortunately, its growth has not been consistent with the master plans, which also overlook sustainable urban development aspects. The high urbanization rate has exacerbated the degradation of the city's environment, including roadside air quality, solid waste, and water quality. The city's ongoing environmental dilapidation has led to a call for a sustainable urbanization to curb past urbanization problems and implement a sustainable future.This work reviews Dar es Salaam's available planning documents and examines how master plans can stimulate sustainable urban development. Findings suggest that master plans should not be used as a mere urban growth control tool. Master plans that are designed and conceptualized as a comprehensive strategy and integrated with different aspects of urban development can play a key role in enforcing sustainable urban development for the city.

城镇化是扩大内需实现中国经济可持续发展的大战略。文章分析了当前中国城镇化发展的战略背景,研究了城镇化发展面临的战略机遇和存在的失衡状况,提出稳步推进城镇化的关键是实施均衡城镇化战略,走大都市与中小城市协调发展的道路。未来不仅要发挥大都市圈的集聚效应和规模效应,也要重视在都市圈以外地区发展中小城市和县城,积极推进农村城镇化。同时要引导劳动力和产业向中西部的回归与转移,促进区域协调发展。

Urbanization plays an important role in expanding domestic demand and promoting economic growth. This paper examines characteristics and challenges in China’s urbanization, focusing on the unbalanced development of urbanization at the present stage. Policy strategies are discussed to promote steady development of urbanization. It is argued that balanced urbanization is the key and should be given top priority. Thus medium and small cities and megacities should be in coordinated development, and transferring of industries and labor forces should be guided to promote balanced development among regions.

坦桑尼亚是中国“一带一路”战略的重要辐射点,中国已成为坦桑尼亚第一大贸易伙伴。本文基于坦桑尼亚全国人口普查资料及分地区统计数据,运用人口密度分析法、人口分布集中指数、人口重心模型和人口偏移增长模型,分析了坦桑尼亚自20世纪80年代末经济变革以来人口分布的空间格局及演变特征。研究结果表明：①坦桑尼亚人口分布以中央铁路线为界,呈现“南疏北密”特征;②1988-2002-2012年间,人口分布不均衡发展的态势不断增强,人口分布重心始终处于中部偏北地区,且有继续北移的趋势;③人口向城市地区集聚是人口再分布的主要过程,中心城市的人口集聚能力不断增强,达累斯萨拉姆省始终处于正向增长的绝对优势地位,以致周边地区出现明显的人口偏移负增长;④铁路和港口等基础设施对人口集聚的作用明显。上述结论对中坦在基础设施建设、住房建设及公共服务方面的合作具有重要意义。

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.

通过对221 BC-1911 AD年间中国城市分布特征及其影响因素的研究,发现：① 在整个研究阶段,中国城市分布的重心位于中东部地区,秦—唐时期重心向西南地区大幅移动,唐—元时期重心先东北方向移动后转向西南方向,元—清时期重心主要向北移动。以腾冲—瑷珲一线为界线分区研究发现,在整个研究阶段西部重心在南北及东西方向呈现出较大的波动趋势,东部重心呈现出与全国类似的运动轨迹。② 标准差椭圆分析表明全国及东西部地区城市分布经历了明显的分散—集聚—分散的变化趋势,其中西部地区最为明显。从城市分布的平均方向看,全国及东部地区具有一定的相似性,均以东北—西南为主要分布特征,西部地区是以西北—东南为主要分布特征。③ 从城市密度分布特征看,其空间连续性和自组织性不断加强且由空间相关性引起的结构性变异处于显著状态。从方向上来看,全方向上的均质化程度呈下降趋势,西北—东南方向各时期城市密度均质化程度相对较好,空间差异相对较小,而东—西方向差异最为明显。④ 分析不同时期城市设置的相关因素发现,221 BC-1911 AD年间,中国城市设置相对集中在地形平坦、气候适中且靠近河流及中心城市的地区。

This paper aims to examine the distribution of cities in China during 221 BC-1911 AD and its influencing factors. Some conclusions can be drawn as follows: (1) the urban distribution gravity center of China during the entire study stage was located in the central and eastern regions and firstly, moved sharply southwestward from the Qin dynasty to the Tang dynasty. Secondly, the gravity center moved toward the northeast from the Tang dynasty to the Yuan dynasty, and then toward the southwest direction. Finally, the gravity center during the Yuan-Qing dynasty moved mainly towards the north direction. In this paper, we divided China into east and west parts by the population line of Tengchong-Aihui and found that during the study period, the gravity center path in the western region presented a large fluctuation trend in both the south-north and the east-west directions. However, the moving trajectory of the gravity center in the eastern region was similar to that of the whole country. (2) The analyses of the standard deviational ellipses showed that the urban distribution in the whole country, the eastern region, and the western region exhibited a distribution pattern of "decentralization, centralization and decentralization", and this trend in the western region was most obvious. From the perspective of the average direction, the urban distribution in the whole country and the eastern region were similar to a certain degree, with the northeast-southwest as the main characteristics. However, the urban distribution in the western region took the northwest-southeast as the main features. (3) Based on the urban density distribution and spatial correlation, we found that its spatial continuity and self-organization were continuously strengthened, and the structural variation was in a significant state. Viewing from the direction, we concluded that the degree of homogenization on the Omni-direction tended to decline. The urban density homogenization degree of each dynasty in the northwest and southeast directions was relatively good and the spatial differences were minimal, but the spatial differences in the east and west directions were most obvious. (4) The analysis of the related factors of the urban setting up in different periods revealed that the setting up of the cities of China during 221 BC-1911 AD mainly focused on the flat terrain near the river and the central city with moderate climate.

为了落实国家新型城镇化规划提出的大中小城市协调发展战略,对1952-2014年中国城市规模分布指数进行演化分析,并在时间序列分析基础上探索了影响因素。结果表明,2000年以来,中国城市规模分布一改长期的分散化趋势,正走向集中化;人口规模增长、政策干预以及城市之间信息和交通成本的节约,都促使城市规模分布分散化;人均GDP长期以来促进了城市规模分布的集中,但近年来开始促进分散化;对外开放水平则主要促进分布的集中。未来应以全国适度均衡发展作为指导方针;远期以市场一体化,近期以共赢互利机制建设为抓手,促进城市群内大中小城市协调分工,优势互补;注意政策的稳定性和长期性,减少城市化格局的人为波动。

After reviewing the literature on city size distribution as well as on its determinants, this paper measures China's city size distribution from 1952 to 2014 based on the rank-size method and explores its evolution trend. Then, we empirically examine which factors and how they determine China's city size distribution to test different hypotheses in previous literature and give a comprehensive explanation of the mechanism of China's city size distribution using the time series analysis. We conclude with policy implications for improving China's city size distribution. The results show that: (1) The city size distribution of Chinese cities follows a power-law, and its evolution shows a decentralized or flattering trend from the 1950s to 2000 and turns to centralization after that; (2) The increase of population size, policy intervention and the reduction of information and transportation costs among cities result in the decentralization of city size distribution; (3) Per capita GDP has a significant U-shaped relationship with city size distribution, that is, the increasing economic development level had led to the centralization of city size distribution at first, but began to bring the decentralization as a result in recent years; (4) The economic openness to the world has promoted the polarization of city size distribution, likely through benefiting large cities more. The urbanization strategies of China in future should 1) aim at keeping an reasonably balanced city size distribution to address the overdevelopment of large cities and the underdevelopment of medium- and small-sized cities; 2) promote coordinated and complementary development of large-, medium- and small-sized cities by developing market integration mechanism in a long period and a mutual benefit strategy in the transition period, based on large urban clusters and city regions centered on large cities; 3) make suggestions to the governments at all levels in regulating the national city size distribution, while paying attention to the stability of policy to reduce the frequent and artificial fluctuations of the urbanization process.

南非是中国在非洲的最大投资目的地与经贸合作伙伴, 特别在基础设施建设方面发展迅速。南非人口空间分布研究对开展中南合作具有重要意义。本文通过收集整理南非历年来的全国人口普查资料统计数据, 运用空间自相关模型、不均衡指数、人口重心模型和偏移—分享模型, 分析了南非人口的空间分布格局和演变特征。研究结果表明, 南非人口分布具有显著的“东高西低”的空间格局, 呈现出以工业化程度较高的大都市区和港口城市为中心的“多核心”集聚的分布特征;空间自相关分析得出人口高集聚区主要分布在大都市区和沿海港口城市, 低密度集聚区主要集中分布在中西部地区;从变化趋势上来看, 1996-2011 年间人口分布不平衡趋势不断加强, 人口重心向西北方向移动;偏移—分享分析表明, 南非人口增长速度先后经历了从1996-2001 年快速增长到2001-2007 年缓慢增长, 再到2007-2011 年高速增长的“高—低—高”增长阶段;省域层面上看, 豪登省和西开普省一直是南非人口集聚较强地区。

South Africa is China's largest trading partner and investment destination in Africa, especially in infrastructure construction. Study of the spatial distribution of South Africa's population is of great significance to the cooperation of the two countries. Based on the census data from 1996 to 2011, this paper describes the spatial pattern and evolving trend of the diverse population of South Africa with time series and cross section data between 1996 and 2011 at county level, based on population density analysis, spatial autocorrelation analysis, population gravity center model, shift-share analysis, and unbalanced index. Using the software platform of ArcGIS and OpenGeoDa, conclusions are made as follows. (1) Population density of South Africa has "high on east and low on west" features, and also has multicore clustering characteristics in metropolitan areas and port cities. (2) Population density varies significantly in different regions. Metropolitan areas and coastal port cities have high population densities, while central and western regions have low population densities. (3) In terms of trend in population change, population distribution in South Africa became more and more imbalanced from 1996 to 2011. The gravity center of population moves to the northwest of South Africa since 1996. (4) Shift-share analysis shows population growth rate have undergone "high-low-high" stages for the last 15 years. At provincial level, Gauteng andWestern Cape have been always the places with dense populations.

Cities in Sub-Saharan Africa are undergoing massive spatial transformation owing to rapid urbanization. For many cities in the Global North, Latin America and Asia, spatial transformation has been traditionally characterised by a shift from monocentric to polycentric urban patterns. In the case of Sub-Saharan Africa, however, it is unclear whether the evolving spatial structure of cities conform to or are explained by existing urban geography models. This paper pursues twofold objectives: one, examines the evolution of the spatial structure of a Sub-Saharan African city-region and its relationship with mainstream urban geography models; and, two, explores the urban planning and policy implications of the spatial transformation. The study draws on spatially explicit data from Kumasi City-Region in Ghana, which is analysed with a set of spatial metrics and an urban growth model. The results indicate that, while the city-region's urban spatial structure before the turn of the Twenty-first century largely conforms to the traditional monocentric model, it is increasingly becoming deconcentrated and dispersive, which suggests a likely pending phase of coalescence in a stochastic fractal urban growth process. Contrary to what is observed in other parts of the world, the declining monocentricity has not transformed into a polycentric urban structure, rather, urban growth is becoming amorphous. There is high level of development spontaneity that cast an image of a city-region that is charting inefficient and unsustainable spatial development path. Urban scholars would have to transcend the frontiers of existing urban structure models to better depict the spatial evolution of sub-Saharan African cities like Kumasi City-Region, while Policy makers need to re-position the Ghanaian planning system to be more influential in delivering sustainable development patterns.

Networks from a wide range of physical, biological, and social systems have been recently described as "small-world" and "scale-free." However, studies disagree whether ecological networks called food webs possess the characteristic path lengths, clustering coefficients, and degree distributions required for membership in these classes of networks. Our analysis suggests that the disagreements are based on selective use of relatively few food webs, as well as analytical decisions that obscure important variability in the data. We analyze a broad range of 16 high-quality food webs, with 25-172 nodes, from a variety of aquatic and terrestrial ecosystems. Food webs generally have much higher complexity, measured as connectance (the fraction of all possible links that are realized in a network), and much smaller size than other networks studied, which have important implications for network topology. Our results resolve prior conflicts by demonstrating that although some food webs have small-world and scale-free structure, most do not if they exceed a relatively low level of connectance. Although food-web degree distributions do not display a universal functional form, observed distributions are systematically related to network connectance and size. Also, although food webs often lack small-world structure because of low clustering, we identify a continuum of real-world networks including food webs whose ratios of observed to random clustering coefficients increase as a power-law function of network size over 7 orders of magnitude. Although food webs are generally not small-world, scale-free networks, food-web topology is consistent with patterns found within those classes of networks.

Diagnostic systems of several kinds are used to distinguish between two classes of events, essentially "signals" and "noise". For them, analysis in terms of the "relative operating characteristic" of signal detection theory provides a precise and valid measure of diagnostic accuracy. It is the only measure available that is uninfluenced by decision biases and prior probabilities, and it places the performances of diverse systems on a common, easily interpreted scale. Representative values of this measure are reported here for systems in medical imaging, materials testing, weather forecasting, information retrieval, polygraph lie detection, and aptitude testing. Though the measure itself is sound, the values obtained from tests of diagnostic systems often require qualification because the test data on which they are based are of unsure quality. A common set of problems in testing is faced in all fields. How well these problems are handled, or can be handled in a given field, determines the degree of confidence that can be placed in a measured value of accuracy. Some fields fare much better than others.