上海市中心区人口密度等值线图

研究人口分布的重要方法是编制人口密度图.通常使用散点图法和分块聚类图法.本文将等值线图的方法引进人口分布的研究领域,根据1990年第四次人口普查资料,绘制了上海市中心区人口密度等值线图。     

新疆南疆县域人口老龄化趋势预测及时空演变特征

随着人口老龄化进一步加剧,对我国社会经济发展产生了更加深远的影响,老龄化问题已然成为研究的热点问题之一.以南疆地区为例,采用队列要素方法,对其人口老龄化发展趋势进行预测,并选取老年人口系数、TAi、TGi和老年人口密度等指标,利用探索性空间分析等方法,探究了南疆地区人口老龄化时空格局及演变特征.结果表明:2010-2030年,南疆地区人口老龄化程度不断加深,呈现“东深-西浅”分布格局,并由东向西、由较发达地区向欠发达地区扩张;南疆地区人口老龄化进程持续加速;南疆地区老年人口密度不断提升,形成“北高-南低”的分布格局,并由北向南扩张;南疆地区人口老龄化存在较强的空间正相关性,空间集聚性呈现先弱后强的变化趋势;人口老龄化高-高区向东北部集聚,低-低区向西南部集聚,且扩张趋势明显.     

2021年广州新中考方案下的数学备考策略

一、前言自2020年广州市数学中考取消考试大纲,回归《标准》后,市教育部门进一步出台了新中考方案.据新方案显示,从2021年起,广州市中考实行全面改革,对考试科目、试卷结构与试卷分值都作了一定调整.中考试题将增强基础性、综合性、应用性和创新性,更注重考查学生对知识技能的掌握情况,以及运用知识分析和解决问题的能力.本文对新旧数学中考方案下的试题分值、难易度及解答题考点分布变化作对比分析,并由此提出新方案背景下的数学中考备考策略.     

基于均方差-TOPSIS模型的环京津地区生态安全格局分析

在P-S-R(压力-状态-响应)模型确立指标体系的基础上,采用均方差-TOPSIS方法对环京津地区2015年生态安全进行测算,并进行空间相关性分析.结果表明:1)人口密度、人均耕地面积、人均GDP、植被覆盖率、人均居住面积、固废无害化处理率、第三产业比重、科教支出占GDP比重、环保投入占GDP比重、生活垃圾无害化处理率等是影响环京津地区生态安全状况的主要因素.2)2015年河北省环京津地区生态安全水平整体上处于一般状态,表现为大聚集小分散状态.3)环京津地区24个县域生态安全表现出较强的自相关性.地区生态安全状况的分布具有明显的地域性.总体表现为北部处于一般状态,南部生态安全水平处于良好状态.     

长三角主要城市空气质量状况与经济社会发展的关联性研究

建立模糊综合模型及面板数据模型对长三角主要城市2006-2013年的空气质量状况进行评价,及对空气质量与主要经济社会因素的关联性进行研究.研究结果表明:长三角主要城市空气质量均在相应的Ⅲ级标准内;经济社会因素的关联程度为:第三产业值对空气质量有正向影响,人口密度、人均生产总值、工业粉尘排放量和第二产业比值这四个指标均对空气质量有负效应.并基于此研究结果进行分析为决策者提供参考,实现长三角地区的可持续发展.     

中国城市土地利用效率的动态测度及影响因素——基于DEA-Tobit两步法的分析

利用数据包络模型(DEA)对中国大陆30个省、市、自治区2001—2010年城市土地利用效率进行了测度与评价,并运用Tobit回归模型对其影响因素进行了深入分析.结果表明:①中国城市土地利用效率总体呈现上升趋势,除少数省区效率值低于0.5以外,其余均保持在0.5-1之间;②城市土地利用效率前沿面分析结果显示,2001—2010年处于生产前沿面的省、市、自治区的数量保持稳定,但其空间分布却发生了一些变化,10年间东部地区减少2个,西部地区增加2个,中部地区一直处于零水平的状态;③城市土地利用过程中高投入低产出局面的扭转、非农从业人员效率的提高是城市土地利用效率改善的基本内核和关键所在;④经济规模对城市士地利用效率呈现正向促进作用,低层次的产业结构和不断增加的人口密度呈现负面影响,政府规制、空间集聚水平、城市规模和区位条件的影响并不显著.     

基于灰色预测模型的广州市城镇生活垃圾清运量预测

基于灰色预测理论,分别用GM(1,1)模型、分数阶GM(1,1)模型和新陈代谢GM (1,1)模型对广州市2015-2019年城镇生活垃圾清运量数据进行建模、检验和比较,结果表明新陈代谢GM(1,1)模型预测精度最高.预测2020-2024年广州市城镇生活垃圾清运量仍呈现长的趋势,在2024年将会突破1000万吨.     

基于DEA-Malmquist方法珠江-西江经济带城市化效率及影响因素

运用DEA-Malmquist方法和R/S分形法测度了珠江-西江经济带2005-2015年城市化效率及演进趋势,再采用面板数据Tobin模型对城市化效率的影响因素进行分析.结果表明,2005-2010年珠江-西江经济带城市化效率大幅下降是由规模效率下降引起的,而2010-2015年城市化效率上升主要由纯技术效率和规模效率同时上升导致;2005-2015年该经济带城市化效率整体呈现波动上升态势且未来呈继续增长的趋势,上升的主要原因是有效的技术进步变化;影响因素方面分析,城市人口密度、政府作用和第三产业对城市化效率的影响为正向,其中城市人口密度的影响明显大于后两者,外商投资对城市化效率影响为负,但影响不显著.     

2022年广州中考压轴题的解法与推广探究

本文以2022年广州市中考第25题为起点,对其解法进行探讨,并对其进行推广探究,得出平行四边形中关于面积和线段长度最小值的若干结论.     

一类震灾人员受损估计方法及应用

为提高震灾人员受损估计模型的精度,本文提出震中烈度、震级、人口密度、房屋损毁面积和地震发生时间5个估计指标,并依据震灾人员受损的"两期"变动规律,将偏正态分布曲线引入震灾人员受损估计中,提出基于修正偏正态曲线的震灾人员受损估计模型。在模型改进上,以震中烈度为主变量,通过数据回归得到偏正态分布估计曲线;进一步,为提高模型的精度和稳定性,采用震级系数、人口密度系数、房屋损毁面积系数和地震发生时间系数对偏正态分布曲线的估计精度进行修正,通过系数的动态变动提高模型的估计精度。验证结果表明,与人工神经网络、多元线性估计曲线、高阶非线性和对数函数等估计模型相比,修正偏正态分布曲线具有敏感度低和估计精度高的优势,能为应急管理部门提供理论依据和方法借鉴。     

Fractal-based exponential distribution of urban density and self-affine fractal forms of cities

Urban population density always follows the exponential distribution and can be described with Clark’s model. Because of this, the spatial distribution of urban population used to be regarded as non-fractal pattern. However, Clark’s model differs from the exponential function in mathematics because that urban population is distributed on the fractal support of landform and land-use form. By using mathematical transform and empirical evidence, we argue that there are self-affine scaling relations and local power laws behind the exponential distribution of urban density. The scale parameter of Clark’s model indicating the characteristic radius of cities is not a real constant, but depends on the urban field we defined. So the exponential model suggests local fractal structure with two kinds of fractal parameters. The parameters can be used to characterize urban space filling, spatial correlation, self-affine properties, and self-organized evolution. The case study of the city of Hangzhou, China, is employed to verify the theoretical inference. Based on the empirical analysis, a three-ring model of cities is presented and a city is conceptually divided into three layers from core to periphery. The scaling region and non-scaling region appear alternately in the city. This model may be helpful for future urban studies and city planning.     

Mathematical models of urban growth

The article models the distribution of cities by population. Two approaches are considered to mathematical modeling of urban growth: a probability model in which the number of cities depends on the population and the rank model of distribution of cities by their population. Five population censuses are analyzed for Russia’s cities. The probability density function n(x, α) for the number of cities as a function of their population x is fitted to all the available censuses with a time-dependent coefficient α . The function α(t ) is approximated and a prediction for the nearest future is computed. In particular, it is shown that in 2010 compared with 2002 the number of large cities should increase, while the number of small town should decrease. A model is also proposed for the interaction of urban areas linked into a single hierarchical system. The model is based on a system of ordinary differential equations describing the change in urban population. Independently of the initial distribution, all the cities and town line up by the rank–size law and deviations from this law, as in real life, are observed only for some large and very small cities. Model parameters are fitted for Russia’s cities.     

Transportation systems and residential location

An optimization model for the spatial allocation of residents in an urban region is presented. The model allocates an exogenously given population on the basis of travel time (to workplaces) and population density criteria and subject to local and subregional capacity constraints. A way of calibrating the ‘value’ parameters of the model on a short-term plan proposal is outlined. Some applications of the model to planning problems of the Stockholm region are reported. These include sensitivity analyses of the population distribution of an adopted plan with respect to its exogenous assumptions (particularly those describing the transportation system). When evaluating investments with long life times, there is a strong need for long-term land use scenarios. Some long-range applications in the field of traffic and energy planning are reported. They can be seen as ‘prolongations’ of the adopted regional plan based on the preferences ‘revealed’ by the calibration procedure. Further extensions of the model to cover cost and energy considerations of urban developments are also outlined.     

Cooperation among mobile individuals with payoff expectations in the spatial prisoner’s dilemma game

We propose a model to address the problem how the evolution of cooperation in a social system depends on the spatial motion and the payoff expectation. In the model, if the actual payoff of an individual is smaller than its payoff expectation, the individual will either move to a new site or simply reverse its current strategy. It turns out that migration of dissatisfied individuals with relatively low expectation level leads to the aggregation of cooperators and promotion of cooperation. Moreover, under appropriate parameters migration leads to some interesting spatiotemporal patterns which seems not to have been reported in previously studied spatial games. Furthermore, it also found that a population with constant expectation can better favor cooperative behavior than a population with adaptive aspiration.     

City expansion model based on population diffusion and road growth

In this paper, a city expansion model is proposed to capture the coevolution relationship between population diffusion and road growth. In the model, we adopt the physical diffusion process, which considers the influence of the road network topology and random exploration factor, to analyse the population diffusion based on the cellular automata (CA) model. In addition, the growth mechanism of the road network is developed to minimize the construction cost related to the population density and the Euclidean distance. The distribution complexities of the population density and the road network topology in the evolution process are then analysed. Compared with the real Beijing city in 2012, the suggested model can be used to describe the city evolution process.     

斑须蝽种群空间分布格局Weibull分布的拟合

Weibull分布的概率密度函数为f(x) =(c/b) [(x -a) /b]c -1exp [(x a) /b]c ,x≥a。本文首次用于拟合班须蝽三代卵块的空间分布 ,8批抽样数据拟合结果表明班须蝽三代卵块在烟田的空间分布遵循Weibull分布。从而丰富了班须蝽种群空间格局的分布理论。同时 ,利用斑须蝽种群空间格局的资料探讨了Weibull分布的参数b、c与种群密度及种群聚集度之间的关系 ,结果表明 ,尺度参数b与种群密度、种群聚集度间均分别存在极显著的线性相关关系 ,形状参数c与种群密度存在极显著的正幂函数相关关系 ,与种群聚集度之间存在极显著负幂函数关系。     

CONTROL OF A METAPOPULATION HARVESTING MODEL FOR BLACK BEARS

ABSTRACT. We develop a metapopulation harvesting model that includes density‐dependent immigration and emigration and apply Pontryagin's maximum principle to derive an optimal harvesting and reserve design strategy. The model is designed to mimic the black bear population of eastern Tennessee and western North Carolina. Model results suggest that a forest region's population can be maintained despite high harvest levels due to emigration from a connected, un‐harvested park region. The amount of shared border between the park and forest region is important in determining the optimal harvesting strategy. This technique offers new insight on the spatial control of protected populations.     

中国生态能源效率时空格局演化及影响因素分析

基于中国2006~2017年的年度统计数据,运用PP与SFA组合模型,构建中国生态能源效率的静态评价模型,对中国30个省、市、自治区的生态能源效率及其影响因素进行分析,运用空间收敛方法和速度激励模型系统的分析了中国生态能源效率的时空格局演化。结果表明:城市化水平、经济开放程度、人口规模和R&D投入等与生态能源效率存在正相关关系;中国的生态能源效率空间格局具有空间分布聚集特征,但空间分布不均衡现象明显;中国的生态能源效率时间格局具有复杂波动的特点,总体趋势是先下降后再上升。     

基于Leslie种群模型的城市流浪猫数量模型研究

城市中日益增多的流浪猫正在成为一个人们关注的问题.其种群个体数量有不同的模型可用于描述,这里应用Leslie种群模型建立了城市雌性流浪猫数量模型,并在此基础上推导了整体数量模型;分析了随时间发展流浪猫数量的性态.根据有关资料数据,给出模型算例,预测了发展趋势.     

USING RESERVES TO PROTECT FISH AND WILDLIFE SIMPLIFIED MODELING APPROACHES

ABSTRACT. This paper investigates theoretically to what extent a nature reserve may protect a uniformly distributed population of fish or wildlife against negative effects of harvesting. Two objectives of this protection are considered: avoidance of population extinction and maintenance of population, at or above a given precautionary population level. The pre‐reserve population is assumed to follow the logistic growth law and two models for post‐reserve population dynamics are formulated and discussed. For Model A by assumption the logistic growth law with a common carrying capacity is valid also for the post‐reserve population growth. In Model B, it is assumed that each sub‐population has its own carrying capacity proportionate to its distribution area. For both models, migration from the high‐density area to the low‐density area is proportional to the density difference. For both models there are two possible outcomes, either a unique globally stable equilibrium, or extinction. The latter may occur when the exploitation effort is above a threshold that is derived explicitly for both models. However, when the migration rate is less than the growth rate both models imply that the reserve can be chosen so that extinction cannot occur. For the opposite case, when migration is large compared to natural growth, a reserve as the only management tool cannot assure survival of the population, but the specific way it increases critical effort is discussed.