排序方式： 共有30条查询结果，搜索用时 125 毫秒
11.
Christopher T. Boyko Mark R. Gaterell Austin R.G. Barber Julie Brown John R. Bryson David Butler Silvio Caputo Maria Caserio Richard Coles Rachel Cooper Gemma Davies Raziyeh Farmani James Hale A. Chantal Hales C. Nicholas Hewitt Dexter V.L. Hunt Lubo Jankovic Ian Jefferson Joanne M. Leach D. Rachel Lombardi Christopher D.F. Rogers 《Global Environmental Change》2012,22(1):245-254
Scenarios are a useful tool to help think about and visualise the future and, as such, are utilised by many policymakers and practitioners. Future scenarios have not been used to explore the urban context in much depth, yet have the potential to provide valuable insights into the robustness of decisions being made today in the name of sustainability. As part of a major research project entitled Urban Futures, a toolkit has been developed in the UK to facilitate the use of scenarios in any urban context and at any scale relevant to that context. The toolkit comprises two key components, namely, (i) a series of indicators comprising both generic and topic area-specific indicators (e.g., air quality, biodiversity, density, water) that measure sustainability performance and (ii) a list of characteristics (i.e., 1–2-sentence statements about a feature, issue or small set of issues) that describe four future scenarios. In combination, these two components enable us to measure the performance of any given sustainability indicator, and establish the relative sensitivity or vulnerability of that indicator to the different future scenarios. An important aspect of the methodology underpinning the toolkit is that it is flexible enough to incorporate new scenarios, characteristics and indicators, thereby allowing the long-term performance of our urban environments to be considered in the broadest possible sense. 相似文献
12.
白垩纪是距今最近的"温室地球"时期,研究其气候演变对认识现今气候环境格局形成及演变具有重要意义。通过对六盘山地区下白垩统六盘山群李洼峡组中段红色、绿色泥岩的元素地球化学特征研究,发现2种泥岩中大部分元素变异趋势相似;化学风化指数(CIA)相当(红色泥岩平均为66.3%,绿色泥岩平均为65.5%),反映中—低化学风化强度;A-CN-K图解显示源岩单一。利用CaCO3质量百分含量,(CaO+Na2O+K2O)/Al2O3,TFeO/Mn,Ti/Sr,Rb/Sr,Sr/Ba比值等指标分析显示泥岩颜色差异与气候背景有关,红色泥岩形成时气候较为稳定,表现为相对湿润且氧化的环境,而绿色泥岩形成时气候波动较大,表现为相对干旱且还原的环境。 相似文献
13.
This paper analyzes the emergence of channeling and preferential flow in heterogeneous porous media. Connectivity is studied
through the statistical characterization of the length L of connected, high velocity patterns in both two-dimensional and three-dimensional media. A simple, physically based, fully
analytic expression for the probability of L has been derived. It is found that the length L of connected, high velocity channels is flow-related and can be much larger than the conductivity integral scale I. Heterogeneity has a considerable impact on emergence of channeling patterns; connectivity is considerably enhanced in three-dimensional
structures as compared to two-dimensional ones. The strong dependence on space dimensionality is a warning against the use
of two-dimensional numerical models for assessing connectivity and preferential flow in heterogeneous media. The probability
p(L) is employed in order to determine the early arrivals of the breakthrough curve at a given control plane; the simple model
can be used for a preliminary assessment of preferential flow. Comparison with numerical simulations confirms that the main
connectivity features were adequately captured by the model. 相似文献
14.
土地一级开发是国内很多大中城市进行城市运营的重要方式,项目管理的理论方法已广泛应用于基建、开发、科研等项目运作。从项目管理的角度对该项活动的实施过程加以分析,将目标管理的方法应用其中,进行充分的目标分析和目标系统设计,可以使土地一级开发的运作更加科学化、系统化。 相似文献
15.
S. Glisovic D. Pesic E. Stojiljkovic T. Golubovic D. Krstic M. Prascevic Z. Jankovic 《International Journal of Environmental Science and Technology》2017,14(10):2301-2320
The functionalities of nano-materials are accompanied by features that are in collision with the postulates of environmental friendliness and sustainability. Nano-related research, part of which is nano-safety, is gaining momentum worldwide, but there is a limited body of knowledge about mechanisms such as the degradation, surface modification and transformation of nanoparticles. This study aims to provide a brief survey on the challenges that researchers and engineers face when attempting to assess the environmental impacts of nano-based products. The applicability of the life cycle assessment method to nanotechnology is briefly explored. The advancement of nano-specific life cycle approaches capable of evaluating the sustainability of these emerging technologies depends on further research on material inventories, the energy efficiency of manufacturing processes, the transport and fate of nanoparticles in the environment, health risks and mitigation techniques. Specialized nano-based product-related databases are still needed to track engineered nano-materials (ENMs) in the environment and to facilitate life cycle inventories and assessment. Permissible exposure limits for key ENMs in the workplace and standardized handling protocols for ENMs are not widely available. Properties that increase their toxicity and bioaccumulation are being increasingly investigated. The dissemination of information to the general public related to risk management is rather sporadic, and the suitability of current regulation for controlling environmental pollution by ENM is subject to continued discussion. Taking into account the environment health and safety challenges mentioned, a suitable expertise and information dissemination network is proposed to take the responsible application of nanotechnology forward in the developing world context. 相似文献
16.
TECTONIC SETTING AND METALLOGENESIS OF THE PRINCIPAL SECTORS OF THE TETHYAN EURASIAN METALLOGENIC BELT 总被引：1，自引：0，他引：1
Slobodan Jankovic 《大地构造与成矿学(英文版)》2001,25(1)
Three global metallogenic belts were formed in the world during Mesozoic and post-Mesozoic times. Two of them are situated along the western and eastern Pacific margins, and the third one - the Tethyan Eurasian metallogenic belt (TEMB) is related to the domain of Eurasian plate and flanked on the south by the Afro-Arabian and Indian plates. The general tectonic evolution of the realm where the TEMB was formed is closely connected with the history of Tethys. The emplacement of ore deposits and the development of regional metallogenic units are related to a definitive time interval and to specific tectonic settings such as: (1) Intracontinental rifting along the northern margin of Gondwana and/or fragments already separated; (2) Oceanic environments (i.e. ophiolite complexes and ocean floor sediments) host podiform chromite deposits, volcano-sedimentary cupriferous pyrite deposits (Cyprus type), stratiform manganese deposits, and sporadically PGE deposits; (3) Subduction related settings involve mainly porphyry copper deposits, hydrothermal massive sulphide polymetallic deposits, and epithermal deposits. So far identified mineralization of porphyry copper exceeds in the TEMB over 100 million tons of copper metal; and(4) Collision and post-collision continent-continent setting includes deposits of lead-zinc, antimony, gold, in some sectors tin deposits, as well. The giant deposits of Li-pegmatite occur sporadically.The TEMB is almost a continuously mineralized belt, but within it, some sectors display specific features of tectonic settings, association of elements, minerals and morphogenetic types of mineralization. 相似文献
17.
Giuseppe Leto Marián Jakubík Tomáš Paulech Luboš Neslušan Piotr A. Dybczyński 《Earth, Moon, and Planets》2009,105(2-4):263-266
We simulate the formation of the Oort cloud (OC) till the age of 2 Gyr starting from an initial disc of planetesimals made by 10 038 test particles. The results on the outer part of the distant comet reservoir are reported by Neslu?an et al. (this issue). Here we deal with the evolution of the population and structure at 2 Gyr of the complementary inner part of the Oort cloud. The dynamical evolution of the massless test particles was followed via the numerical integration of their orbits. We considered the perturbations produced by four giant planets assuming they have their current orbits and masses, as well as the perturbations caused by the Galactic tide and passing stars. The efficiency of the formation of inner OC is found to be very low: only about 1.1% of all considered particles ended in this part of the OC. At 2 Gyr, the dynamics of the inner cloud is mainly governed by the dominant z-term of the Galactic tide. The number density of the bodies is proportional to the heliocentric distance, r, as r ?3.53. The directional distribution of orbits is still strongly inhomogeneous. There are large empty regions in the space angles around the Galactic Equator points with the galactic longitude 90 and 270° (non-rotating frame), or there are only few bodies having the ecliptical latitude higher than +60° or lower than 60°. A strong concentration of objects at the Ecliptic is apparent up to ≈1,000 AU, with a possible—but still not proved—extension to ≈1,500 AU. Beyond r ≈ 6,000 AU, bodies directly above and below the Sun, with respect to the Ecliptic, are absent. 相似文献
18.
A.?FioriEmail author I.?Jankovic G.?Dagan 《Stochastic Environmental Research and Risk Assessment (SERRA)》2003,17(6):370-383
Flow and transport take place in a heterogeneous medium made up from inclusions of conductivity K submerged in a matrix of conductivity K
0. We consider two-dimensional isotropic media, with circular inclusions of uniform radii, that are placed at random and without overlap in the matrix. The system is completely characterized by the conductivity contrast =K/K
0 and by the volume fraction n. The flow is uniform in the mean, of velocity U=const. The derivation of the velocity field is achieved by a numerical method of high accuracy, based on analytical elements. Approximate analytical solutions are derived by a few methods: composite elements, effective medium, dilute systems and first-order approximation in logconductivity variance. The latter was employed by Rubin (1995), while the dilute system approximation was used by Eames and Bush (1999) and Dagan and Lessoff (2001). Transport is solved in a Lagrangean framework, with trajectories determined numerically from the velocity field, by particle tracking. Results for the velocity variance and for the longitudinal macrodispersivity, for a few values of and n, are presented in Part 2. 相似文献
19.
A. J. Rabideau L. S. Matott I. Jankovic J. R. Craig M. W. Becker 《Environmental Geology》2005,48(1):57-67
Groundwater modelers have embraced the use of automated calibration tools based on classical nonlinear regression techniques. While clearly an improvement over trial-and-error calibration, it is not clear to what extent these popular inverse modeling tools yield accurate parameter sets for groundwater flow models. The impact of model configuration and precision upon automated parameter estimation is also unclear. An extensive set of numerical experiments was performed to explore the influence of model configuration on the calibration of a regional groundwater flow model developed using the analytic element method. The results provided insight into the manner in which the specified level of model precision and the location of observation points influence the results of inverse modeling based on nonlinear regression. While the importance of these issues is application-specific, obtaining an accurate model calibration for the case study required both a careful placement of test observations and a greater-than-anticipated level of model precision. The required level of model precision for calibration was more than necessary to produce an acceptable flow solution. 相似文献
20.
Prof. Dr. S. Jankovic 《International Journal of Earth Sciences》1990,79(2):467-478
The principal copper deposits associated with Upper Creataceous — Laramian calc-alkaline volcano-plutonic complexes in the Bor district are classified as follows: Volcanogenic massive sulphide deposits are situated in andesitic volcanics, and are composed of pyrite and copper sulphides. Multistage deposition of mineral associations in this area was controlled mainly by secondary boiling of hydrothermal fluids rich in sulphur. Apart from cupriferous pyrite deposits, volcanogenic massive polymetallic deposits, containing a pyritic ZnCu+Pb association, have been found recently in hydrothermally altered dacite- and esite pyroclastics. Porphyry copper deposits are mainly situated in volcanic piles related to subvolcanic intrusions and/or hypabyssal plutons. Some porphyry copper deposits occur in the same structures with massive sulphide orebodies, lying above the porphyry copper system. Conglomerate-type ores consisting of clasts of massive sulphide in an andesitic pile have been discovered recently. 相似文献