南京市区建设用地扩张模式、功能演化与机理

以南京市区不同时段遥感影像为基础,在综合凸壳方法与公共边方法基础上,通过矩阵分析对1985-2007年南京市区建设用地扩张模式进行划分,探讨不同扩张模式的空间结构特征。结果表明：① 1985年以来,南京市区建设用地扩张迅速。其中,填充扩张由主城区逐渐向外推移,飞地扩张分散在远离主城区的开发区、工业园及大学城内,蔓延扩张则介于二者之间,多表现为前期扩张的继续发展。② 功能上,填充扩张由居住主导向居住与工业混合转变;蔓延扩张由居住与工业混合向工业主导转变;飞地扩张一直以工业主导,并伴随科教的区域性集中。③ 驱动机理,填充与蔓延扩张属于收益驱动型,飞地扩张更多地受成本制约。随着城市空间向外拓展,建设用地扩张的成本约束作用均逐渐加强;而城市建设用地中工业用地比重的增加,又使三种扩张模式的收益驱动作用加强。     

Precise GPS Positioning by Applying Ionospheric Corrections from an Active Control Network

In this article, initial results are presented of a method to improve fast carrier phase ambiguity resolution over longer baselines (with lengths up to about 200 km). The ionospheric delays in the global positioning system (GPS) data of these long baselines mainly hamper successful integer ambiguity resolution, a prerequisite to obtain precise positions within very short observation time spans. A way to correct the data for significant ionospheric effects is to have a GPS user operate within an active or permanently operating network use ionospheric estimates from this network. A simple way to do so is to interpolate these ionospheric estimates based on the expected spatial behaviour of the ionospheric delays. In this article such a technique is demonstrated for the Dutch Active Control Network (AGRS.NL). One hour of data is used from 4 of the 5 reference stations to obtain very precise ionospheric corrections after fixing of the integer ambiguities within this network. This is no problem because of the relatively long observation time span and known positions of the stations of the AGRS.NL. Next these interpolated corrections are used to correct the GPS data from the fifth station for its ionospheric effects. Initial conclusions about the performance of this technique are drawn in terms of improvement of integer ambiguity resolution for this baseline. ? 1999 John Wiley & Sons, Inc.     

Some thoughts on spatial data and structure analysis

The discussion is structured around two themes, namely spatial data analysis and spatial structure/process analysis. With respect to spatial data analysis, I concentrate on the issues related to geographical information systems (GIS), as well as spatial data mining and knowledge discovery in databases. With reference to spatial structure/process analysis, the emphasis is placed on the analysis of complex systems.     

Magnetostratigraphic reinvestigation of the Palaeocene/Eocene boundary interval in Hole 690B, Maud Rise, Antarctica

Hole 690B, drilled on Maud Rise near Antarctica, provides one of the most important Palaeocene/Eocene boundary interval sections. Magnetostratigraphy plays a key role in dating Palaeocene/Eocene boundary events, but there are two problems with the published scheme in Hole 690B. The first concerns major mismatches of several magnetozones and biozones in the succession. The second is an unexplained pervasive declination cluster, which should not be present in these azimuthally unoriented piston cores. To resolve these issues, a palaeomagnetic reinvestigation was carried out on 98 specimens from 12 cores through the upper Palaeocene–middle Eocene section in Hole 690B.
The bulk of the samples carry an approximately uniformly directed magnetically hard component resulting in a declination cluster effectively identical to that of the earlier study. The spurious magnetization can be explained either as an 'inward-radial magnetization' or as a 'core-split overprint'. By estimating the extent of the overprint within each sample, it has been possible to construct a filtered magnetostratigraphy for the section. The result is that many of the magnetozone–biozone mismatches are eliminated, and the record of the 2.5 Myr Chron C24r, which brackets the various events associated with the Palaeocene/Eocene boundary, is considerably cleaner. It is not possible to define the upper and lower boundaries of this magnetochron, so we recommend that the dating of the events within this section be based on the biostratigraphy only.     

环境规制对无锡市制造业结构优化与绩效的影响

环境规制已成为促进区域发展方式转变和经济可持续发展的重要驱动力.本文以无锡市太湖水危机事件为例,首先对水危机前后的环境规制政策和手段进行对比分析,其次结合现有理论研究,总结了环境规制对制造业产业结构优化和绩效影响的理论框架,最后在对环境规制强度进行定量评估和对影响产业绩效各要素分析的基础上对理论框架进行验证.环境规制强度的评价结果表明,水危机事件后,环境规制强度显著增加,政府、技术、市场及社会工具的环境规制强度均值在2007-2009年期间比2001-2006年期间分别增加了2.2、1.0、2.6、0.7倍,政府在加强行政管理的同时开始积极探索市场化治理的工具,但以政府规制为主的治理模式仍然没有改变.回归结果进一步表明环境规制通过影响企业准入和提高技术效率,实现产业结构的优化和生产效率的提高,抵消了环境规制对生产成本增加而产生的消极作用,但是创新仍没有成为产业绩效增加的最主要动力.本研究对探讨经济和环境可持续发展模式以及环境规制手段的合理运用具有重要的理论借鉴意义.     

Behavioral patterns of Fuego volcano, Guatemala

The times of activity at Fuego (one of the most active volcanoes in the world) since 1800 correlate with the activity of other Central American volcanoes. Approximately 0.7 km³ of olivine-bearing, high-Al₂O₃ basalt has been erupted since 1932, and about 1.7 km³ has been produced during 450 years of historic records. A minimum of 13,000 years and a maximum of 100,000 years were required to build Fuego's cone of 50 km³. Within the recent cluster of activity since 1932, rates of magma production have increased to 0.5 m³/s and the trend has been toward more eruptions (shorter reposes) of progressively more mafic basalt. 47% of the eruptions occurred within 2 days of the fortnightly tidal maximum and 56% occurred within 2 hours of the semi-diurnal minimum of the vertical tidal gravity acceleration. Thus the maximum compressional component of the tidal cycles can trigger an eruption at Fuego. Eruptions with higher effusion rates produce larger volumes of materials, although they only last a few hours. The 20–70 year clusters of activity beginning at 80–170-year intervals are interpreted as reflecting the ascent of primary batches of magma. A deeper (8–16 km), larger (> 1 km³) primary chamber and a shallower (2–5 km), smaller (0.1 km³), dike-like secondary chamber best explain Fuego's behavioral pattern.     

Stochastic seismic slope stability assessment using polynomial chaos expansions combined with relevance vector machine

This paper presents probabilistic assessment of seismically-induced slope displacements considering uncertainties of seismic ground motions and soil properties.A stochastic ground motion model representing both the temporal and spectral non-stationarity of earthquake shakings and a three-dimensional rotational failure mechanism are integrated to assess Newmark-type slope displacements.A new probabilistic approach that incorporates machine learning in metamodeling technique is proposed,by combining relevance vector machine with polynomial chaos expansions(RVM-PCE).Compared with other PCE methods,the proposed RVM-PCE is shown to be more effective in estimating failure probabilities.The sensitivity and relative influence of each random input parameter to the slope displacements are discussed.Finally,the fragility curves for slope displacements are established for sitespecific soil conditions and earthquake hazard levels.The results indicate that the slope displacement is more sensitive to the intensities and strong shaking durations of seismic ground motions than the frequency contents,and a critical Arias intensity that leads to the maximum annual failure probabilities can be identified by the proposed approach.     

A spatially distributed model for the assessment of land use impacts on stream temperature in small urban watersheds

Stream temperatures in urban watersheds are influenced to a high degree by changes in landscape and climate, which can occur at small temporal and spatial scales. Here, we describe a modelling system that integrates the distributed hydrologic soil vegetation model with the semi‐Lagrangian stream temperature model RBM. It has the capability to simulate spatially distributed hydrology and water temperature over the entire network at high time and space resolutions, as well as to represent riparian shading effects on stream temperatures. We demonstrate the modelling system through application to the Mercer Creek watershed, a small urban catchment near Bellevue, Washington. The results suggest that the model was able to produce realistic streamflow and water temperature predictions that are consistent with observations. We use the modelling construct to characterize impacts of land use change and near‐stream vegetation change on stream temperatures and explore the sensitivity of stream temperature to changes in land use and riparian vegetation. The results suggest that, notwithstanding general warming as a result of climate change over the last century, there have been concurrent increases in low flows as a result of urbanization and deforestation, which more or less offset the effects of a warmer climate on stream temperatures. On the other hand, loss of riparian vegetation plays a more important role in modulating water temperatures, in particular, on annual maximum temperature (around 4 °C), which could be mostly reversed by restoring riparian vegetation in a fairly narrow corridor – a finding that has important implications for management of the riparian corridor. Copyright © 2014 John Wiley & Sons, Ltd.     

Centrifuge modelling of caisson breakwater subject to wave-breaking impacts

Model tests were conducted to investigate the behaviour of caisson breakwater resting on sand beds subject to impacts due to wave breaking. The centrifuge modelling technique was employed to simulate the prototype stress levels in the foundation soil as the behaviour of sand is highly stress dependent. A wave actuator was developed to simulate the wave-breaking impact loads on the caisson during centrifuge flight. The test results reveal that the vertical and horizontal movements and tilt of the caisson breakwater increase progressively with the number of breaking-wave impacts. The excess pore pressures developed in the foundation sand under non-reversal loading are generally small and appear insignificant. The results of the parametric studies conducted to examine the effects of impact-load pattern, caisson width, rock berm beneath caisson, wave slamming on top slab of caisson and cyclic preloading on the performance of caisson breakwater are also presented. The practical implications of the experimental findings in the present study are also highlighted in this paper.     

Nutrient distributions in baroclinic eddies of the oligotrophic North Atlantic and inferred impacts on biology

High-sensitivity (nanomolar) techniques for nitrate and phosphate were applied to study nutrient patterns in the euphotic zone of mesoscale eddies in the Sargasso Sea during the EDDIES project. Surface concentrations of nitrate plus nitrite (DNN) and phosphate (DIP) were found in the range of 1–20 nM with substantial spatial variability in the eddies, with resulting mean N:P molar ratios of 2.1. Chlorophyll biomass was well correlated with DNN but not DIP in the upper euphotic zone, suggesting N-limitation of marine phytoplankton at this time of year. Within the upper 140 m, the water column experienced a transition from a P-enriched (relative to Redfield ratio) shallow layer to a N-enriched deep layer, which may suggest downward transport and subsequent remineralization of high N/P biogenic products presumably originating from N₂ fixation. Chlorophyll biomass in the deep chlorophyll maximum of eddies was found to be tightly related to eddy–induced variability in major nutrients (N, P, Si) and nutrient stoichiometry, suggesting that the impact of eddies on biology is through control of nutrient availability. Because the eddies were likely to be in various phases of development (different degrees of both biological and physical maturity), full interpretation of eddy data and dynamics will require better coverage of a full eddy life cycle.