Convecting towards the catastrophe of substorm onset

A nonlinear model of substorm evolution is constructed which self-consistently unifies the directly driven and the loading-unloading systems. Using only the principle that the magnetosphere minimizes its potential energy within the constraints imposed by external conditions, substorms are described with reference to trajectories on a cusp catastrophe surface. The model predicts the conditions required for substorm onset and the amount of energy explosively released at the beginning of the expansive phase.     

The relationship between electron temperature and electron density under quiet conditions in the auroral zone

A theoretical model is described which predicts electron temperature in the day-time F-region above EISCAT on geomagnetically quiet days, given the observed values of electron concentration, ion temperature and heat conduction, the daily average of solar radiation at 10.7cm and the MSIS-86 model of the neutral atmosphere. The values predicted by the model agree very closely with the observed temperatures, both for average conditions and for individual days. On two occasions the onset of a geomagnetic disturbance after a period of quiet conditions was accompanied by a growing divergence between the predicted and observed values, which corresponds to an additional source of electron heating such as would be provided by low energy particle precipitation.     

Energy efficiency left behind? Policy assemblages in Sweden’s most climate-smart city

ABSTRACT

Smart city experiments have the potential to reshape urban climate change governance. Smart city initiatives have been supported by international technology companies and the European Union for many years and continue to be promoted by national and municipal governments. In relation to sustainability and climate change, such initiatives promise more efficient use of resources through the use of information and communications technology in energy infrastructure. Experiments with smart city technologies such as urban smart grids have shown the potential to restructure relationships between energy utilities, energy users and other actors by reconfiguring the dynamics of energy supply and demand. But do urban experiments lead to institutional change? The aim of the article is to provide a better understanding of how smart city experiments reshape the urban governance of building energy use. Hyllie, a new city district in Malmö, Sweden, was home to two smart city experiments that contributed to the institutionalization of urban smart grid technology. However, the analysis of Hyllie’s policy assemblages shows that this institutional change could redefine sustainability at the expense of energy efficiency.     

绿色建筑概念下历史文化名城保护综合评价研究

本文以青海省同仁历史文化名城保护规划为例,从绿色建筑概念出发,结合我国国情和时代特点,利用AHP模型构建了"历史文化名城保护综合评价指标体系"。要求历史文化名城保护规划、设计遵循绿色建筑的设计方法,着眼于对地方技术及建筑历史的尊重、资源与能源的有效利用、防止环境污染,确保从建筑单体到城市整体环境逐步实现自然生态、社会生态、经济生态和历史文化生态的平衡、协调发展。使得管理部门、规划师、建筑师、业主等能够更加明确评价项目的依据以及可采用的改进措施等,也可实现从多个规划、设计方案中进行优选。     

European plans for the smart city: from theories and rules to logistics test case

City evolution is connected to social, economic and technological evolutions. New technologies induce further changes, which are highly innovative, which again affect the urban and territorial systems. The city once again adjusts to new opportunities in relation to information and communications technologies, energy and mobility. In this paper, smart city, configured as a set of interacting systems with people, is focused as a possible model to follow for pursuing sustainability in real cities of the twenty-first century. Three processes are recalled: city development, city planning theories and city rules. Smart city seems to be the convergent point for all processes evolving in European urban areas. Theoretical definitions of smart city are recalled. At the same time, the European Commission is promoting smart city rules for implementation. Moreover, in the last years some local decision-makers implemented specific measures that today can be considered in the class of smart city measures. The objective of the paper is to analyse the European perspectives for smart city, trying to separate the three processes that are strongly integrated, but without formal links. To verify the European smart city approach, a study case concerning city logistics is considered.     

SHARABLE INPUTS,PRODUCT VARIETY,AND CITY SIZES*

In this paper, I investigate some of the causes of city formation in spatial economies. A model is proposed in which an intermediate differentiated input shared by more than one industry is the cause of the formation of diversified cities. The desire of both the traded-good and the local-good industries to employ a variety of inputs from the intermediate industry provides the reason for the agglomeration of the three industries. In addition, the paper contains a comparative-statics analysis of the model in an open and a closed-city framework. It is demonstrated that the larger the city, the more variety of intermediate inputs the city can provide and the more specialized it is in the production of the traded-good. Moreover, the model suggests that different industrial structures will result in different city Sizes.     

Hydraulic Analysis of a Self-Cleaning Drainage Outlet at the Hellenistic City of Priene

At the distal western end of a main drainage canal running along West Gate Street in the Hellenistic city of Priene, an unusual masonry outlet structure has been found. The housed structure contains a doubly curvilinear, contracting rectangular cross-section flow passageway that allows drainage water flow through the city perimeter wall. A computer model of the complexly-shaped drainage structure has been hydraulically analysed in order to determine the function of the curvilinear passageway. Results indicate that the internal shaping of the structure hydraulically conditions the flow to create multiple circulatory mixing flows that agitate and entrain debris in the outflow stream sufficient to “self-clean” the outlet, thus preventing clogging. Further calculations of flow free surface shapes at different flow rates indicate the maximum flow capacity that can be processed by the drainage system without overspillage to provide a lower-bound estimate of the steady-state water supply to the city. The design of a self-cleaning, continuous flow urban wastewater system implies that Greek city planners maintained a high level of awareness about the hygienic conditions needed to maintain the health of the populace. The Greek attitude toward technical refinements necessary to improve the quality of urban life could therefore not be better represented than in attention to detail related to water supply and waste water drainage systems as a key to improved life standards.     

The Tell Abu Duwari Project, 1988–1990

Abstract

The second (1988–1989) and third (1990) seasons of excavation and survey at the 2nd-millennium B.C. urban site of Tell Abu Duwari (ancient Mashkan-shapir), Iraq, have yielded important new evidence on the organization of ancient Mesopotamian cities. A combination of aerial and surface survey has provided a broad overview of the differing functional areas, and of the role played by canals, streets, and walls to divide the city. Excavations consisted of both small soundings and one broad horizontal exposure. The soundings were designed to test the relationship between surface traces and the remains beneath the ground, and the larger excavation generated an artifactual, faunal, and floral inventory from an administrative district which will be compared with similar collections excavated in other parts of the city in future seasons.     

试论现代物流业与港口城市空间再造——以大连市为例

伴随着全球化的深入和世界性的产业转移高潮,处于全球供应链枢纽节点地位的大型港口城市在物流经济中起着越来越强大的极核作用。现代物流业在港口城市飞速发展,必将引起港口城市的产业结构和功能分区变化,并通过港口物流发展带动物流企业集聚、大型物流园区兴起、构建城市型轴--辐物流网络主导物流配送网点布局,参与港口城市空间再造。本文运用经济学和城市地理学的相关理论,结合大连市现代物流业发展予以论证。     

Determinants of Residential Location Choice: How Important Are Local Public Goods in Attracting Homeowners to Central City Locations?*

Abstract. A hybrid conditional logit choice model is estimated using data on the characteristics and destination of homeowners who engaged in intrametropolitan moves among 17 school districts within the Columbus, Ohio area in 1995. The model is used to test the relative influence of local fiscal and public goods versus household‐level characteristics in determining household location choices across central city and suburban school districts. Results provide evidence of both a “natural evolution” of households to the suburbs, due to job location, residential filtering, and household income and lifecycle effects, and “flight from blight,” due to lower school quality, higher crime levels, and lower average income levels in the city. In comparing the magnitudes of these variables, we find that school quality exerts the strongest influence: a 1‐percent increase in the school quality of the city district increases the probability of choosing a city residence by 3.7 percent. In contrast, the effects of household income and other individual characteristics are relatively modest. The findings provide support for a “flight from blight” suburbanization process that is dominated by differences in neighborhood quality between the city and suburbs. An implication is that investments that promote central city development and reduce suburbanization are justified on efficiency grounds if negative externalities are generated by increased concentration of poverty, crime, and low school quality.     

省际边界区域城市化模式研究

从边界对基础设施、经济要素、产业扩张、市场、生态环境的"切变"效应入手,首次提出我国省际边界区域的"水平城市化模式"。这种模式具有边缘性、断裂性和竞合性等特征,可分为"强强"、"强弱"、"弱弱"等组合类型。通过对苏鲁边界区域的徐州和济宁2市城市化模式的初步探索,验证了水平城市化模式在省际边界区域的客观存在。在边界"切变"效应的作用下,竞争性往往大于合作性,甚至会引起恶性竞争,通过区域管治等措施,可以促进省际边界区域城市一体化目标的实现。     

The development and evolution of “cerebral thermometry”: The physiology underlying a nineteenth-century approach to cerebral localization and neurological diagnosis

ABSTRACT

Surface thermometers were developed in the latter half of the nineteenth century. From the 1850s through the 1880s, collaborations between physicians, research scientists, and instrument makers produced clear improvements in the technology to measure cranial surface temperatures, with development of self-registering mercury surface thermometers resistant to pressure and little influenced by ambient temperature, apparatus for recording cranial surface temperatures from multiple stations simultaneously, and development of thermoelectric apparatus. Physiologic studies of cranial surface thermometry were conducted over a quarter century from 1861 to 1886. Beginning in the 1860s Albers in Bonn, Germany, and Lombard at Harvard and later in England systematically investigated surface temperatures on the head using surface thermometers and thermoelectric apparatus; they demonstrated that head temperatures were variable over time and across individuals and were not clearly influenced by thinking or muscular contraction but were influenced by ambient air temperature. In 1880 Amidon in the United States claimed that cranial surface thermometry during exertion produced localized increases in surface temperature on the contralateral scalp in a specific pattern (“external motive areas”) indicating underlying brain areas responsible for each movement. Amidon’s results were not reproduced by experienced physiologists in England or France. Contemporaries recognized that significant technical and practical problems limited the accuracy and reliability of cranial surface thermometry. Physiological studies of cranial surface thermometry ended in the mid 1880s, although some clinicians who were early advocates promoted its use in clinical contexts into the early twentieth century.     

城市系统中的竞争与协同机制研究

本文在剖析城市自组织系统耗散结构特征的基础上,重点从区域尺度和城市尺度两种空间尺度解析城市系统自组织演化的驱动力:竞争与协同。研究表明竞争与协同两种力量共同决定城市系统的发展演化,协同性竞争(良性的竞争)有利于城市系统的发展,推进城市可持续发展;反之,过度竞争或竞争乏力则会导致产生无序状态的产生,阻碍城市的发展。     

元大都内部河湖水系的空间分布特点

元大都内部的河湖水系基本上归为两大系统:一是以白浮泉为源头的高粱河-积水潭水系,一是以玉泉山泉水为源头的金水河-太液池水系。两套水系在城市中发挥了不同的功能,并与元大都的礼制原则相融合,共同构成了这座独具特色的东方山水城市。本文在侯仁之的工作基础上,对元大都内部的河湖水系做了进一步的系统研究,较为准确地复原了元大都城内积水潭水系的结构和分布范围;根据各种历史文献记载、结合地形分析,对金水河的位置和走向提出了新的见解,并对元大都水系结构与城市形态的关系进行了探讨。     

CULTURAL IDENTITY AND KNOWLEDGE CREATION IN COSMOPOLITAN CITIES*

ABSTRACT We study how the city system is affected by the possibility for the members of the same cultural diaspora to interact across different cities. In so doing, we propose a simple two‐city model with two mobile cultural groups. A localized externality fosters the productivity of individuals when groups interact in a city. At the same time, such interaction dilutes cultural identities and reduces the consumption of culture‐specific goods and services. We show that the two groups segregate in different cities when diaspora members find it hard to communicate at distance whereas they integrate in multicultural cities when communication is easy. The model generates situations in which segregation is an equilibrium but is Pareto dominated by integration.     

The Green Energy Transition and Peripheral City Development in China: Towards a Local Eco-developmental State

The green energy transition is recognized for its inherent environmental contributions. This article illustrates how it can also reshape the economic landscape and create the conditions for a peripheral city to develop. Drawing on the politics of accelerating low-carbon transition and focusing on the role that local governments play in this process, the authors illustrate how the green energy transition has commercialized wind and solar resources and constructed a new resource control system in northwest China. The Gobi Desert has extensive wind and solar energy resources; having the authority to grant access to preferential sites to exploit these resources empowers local governments to combine their interests with those of other stakeholders to build local capacity and achieve developmental goals. Governments are also able to manipulate renewable energy curtailments to promote infrastructure investment, technological progress, and the grid-parity model. The green energy transition can therefore play a role in upgrading industrial structures, alleviating local poverty, narrowing regional development gaps, and contributing to national environmental improvement. This study provides a theoretical contribution to our understanding of how the local eco-developmental state configures new energy spaces and restructures local governance, and argues that green industrial policies are sometimes actively nurtured by local rather than central governments.     

Place-to-Place Rent Comparisons among Canadian Cities

This paper estimates average monthly gross rents for comparable rented private-sector accommodation in Census Metropolitan Areas across Canada. By “gross rent” is meant the typical monthly payment in a CMA for a principal residence by a tenant of given traits under the conditions of a standard lease to a for-profit landlord in competitive market equilibrium for premises used exclusively for accommodation, in an arm's length transaction, and includes heating and utility expenses where paid separately by the tenant. A single average gross rent is estimated for each city for dwellings and households, each with specified characteristics. This paper reviews the application of hedonic price models for this purpose, identifies shortcomings of current research in the field, and suggests a new form for such models. This new model is estimated using microlevel data from a sample of renter households taken across the twenty-three largest urban areas in Canada. A classical version of the model is fitted first to renter data for individual cities, and its limitations assessed. A measure of “relative supply” is introduced to help explain city to city variations in the hedonic prices. Then an all-city new model is estimated which incorporates relative supplies. This all-city model is then used to derive place-to-place rent comparisons.     

Monitoring the Near‐surface Urban Heat Island in Beijing,China by Satellite Remote Sensing

Urban heat island (UHI) effect is an important impact factor of the regional climate and ecological environment. How to observe and analyse the spatial distribution of UHI has become an important issue of urban environmental research. In this paper, the near‐surface air temperature of Beijing was derived based on the Landsat/TM satellite imagery on 26 July 2011 to study the near‐surface UHI. A statistical model at 195‐m window size was established to estimate the air temperature, using land surface temperature, normalized difference vegetation index, altitude, and surface albedo as independent variables. The mean absolute error (MAE) of the model was 0.87°C, and the R² was 0.66, indicating that the method can be used to effectively estimate the air temperature. The air temperature distribution obtained from remote sensing revealed that the UHI effect in Beijing was very significant and showed a concentrated pattern. The heat island intensity was stronger in the southern part than in the northern part of the city. In addition, the relationship between the air temperature and impervious surfaces was analysed. The air temperature increased with increasing impervious surface coverage, and the rate of change depended on the impervious surface coverage. When the impervious surface coverage was below 40 per cent, the temperature increased rapidly with increasing impervious surface coverage, and when the impervious surface coverage was above 40 per cent, the temperature increased slowly. This study provides a new approach to monitor near‐surface UHI and reveals its relationship with impervious surface, providing a scientific reference for urban planning and environmental assessment.     

河南南阳市发现明代琉璃房屋模型

1994年,文物工作者在对南阳市城内的明代王府花园进行整修时,在假山的盘山道上清理出琉璃残件。经 修复,确定为一件明代的琉璃房屋模型。该模型系青绿色,为手制、模制兼施,应属于明代王府花园假山中的饰品。