DELINEATING METROPOLITAN AREAS USING LAND PRICES*

ABSTRACT This paper proposes an approach to delineating metropolitan areas that is more general than the standard approaches in three respects: First, it uses the fraction of land prices attributable to economies of urban agglomeration instead of using commuting intensities as an indicator of economic integration between metropolitan centers and their hinterlands. Second, it identifies metropolitan centers endogenously instead of determining them exogenously. And third, it takes metropolitan subcenters explicitly into account. An empirical illustration is used to show that the approach tends to delineate fewer but larger metropolitan areas in densely populated regions, and smaller metropolitan areas in sparsely populated regions.     

生机勃勃的藏东南

It was not long ago that I took National Highways 318,212,and 317 to get to Nyingchi and Chamdo and conduct various interviews.The place is a mysterious land in the southeastern reaches of Tibet,and while I was there,I saw development and vitality everywhere as a result of the prosperity sweeping across the region.     

JIULONG,LAND OF FAIRY TALES

The area is situated at the end of the land's snow line,along the southern part of Mt. Gonggya(the "Mountain King in Sichuan Province") and at the intersection of Panchi Hua, Xichang Plain, and the Qinghai-Tibet Plateau.     

SEISMIC PROTECTION OF LIGHT SECONDARY SYSTEMS THROUGH DIFFERENT BASE ISOLATION SYSTEMS

The objective of the present work is to examine advantages and drawbacks of different types of isolation systems, when seismic isolation is used as a protection strategy against damage to internal equipment and contents. The starting point of the study is the big experimental program of table tests on reduced-scale R/C structural models, carried out within the MANSIDE (Memory Alloys for New Seismic Isolation DEvices) project. Seven identical l:3.3-scaled, 3-storey frames were tested, including two fixed-base models and four base-isolated models with different isolation systems, namely: (1) rubber isolators, (2) steel-hysteretic system and (3), re-centring SMA (Shape Memory Alloy) system. In this study the internal equipment is regarded as an elastic single degree of freedom, with 2% equivalent viscous damping. Therefore, the capability of fixed-base and base-isolated models with different isolation systems to protect light secondary systems is evaluated by comparing the floor response spectra obtained from the storey accelerations recorded during shaking table tests. Three different PGA's are considered, about 0.15g, 0.3g and 0.5g, respectively. All the shaking table tests are also simulated with an accurate numerical model, to validate and better understand the experimental results. It is found that each type of isolation system reduces considerably the seismic effects on internal equipments in wide frequency regions. However, tuning effects may arise in specific frequency ranges, corresponding to the first mode in structures equipped with quasi-elastic (rubber) isolation systems, and to higher modes in structures equipped with elasto-plastic (steel) and nonlinear re-centering (SMA) isolation systems.     

ADDITIVE-RATIO MEASURES OF INTERACTMTY IN INPUT-OUTPUT SYSTEMS

ABSTRACT. A general axiomatic framework is developed for analyzing alternative measures of interactivity between the sectors of a given activity system (such as the industrial sectors of an economy). Within this overall framework, we analyze an ordinal class of additive-ratio measures which has been applied to a wide variety of systems, including both economic and ecological systems of activities. Our main result is to show that such measures can be characterized by four interactivity axioms. In addition, a wide variety of alternative measures are compared to additive-ratio measures in terms of this axiom system.     

TRAVELOGUE ON THE UNINHABITED LAND OF NORTH TIBET

<正>Setting foot on the eternally snow-covered Qinghai-Tibet national road and heading to the"roof of the world",my gaze was unavoidably fixed on the vast but harsh conditions in the north-west of the Tibetan plateau.This is the"Changtang uninhabited land"to which people so often refer. It has been about 20 years since I last encountered the"uninhabited land"of North Tibet.Surprisingly,however,today I find this mysterious land has undergone an earthshaking change.