Fisheries property rights and recreational/commercial conflict: implications of policy developments in Australia and New Zealand     

《Marine Policy》2001,25(1):49-59

Commercial fisheries management in Australia and New Zealand is increasingly based on better definition of the rights and responsibilities of resource users. At the same time recreational fishers are claiming a greater share of resources largely based on perceptions of superior economic returns to the community from their activities. The basis of the conflict between traditional, recreational and commercial resource users is moving from physical competition for fish to economic and legal arguments over social priorities. Advantages and disadvantages of increased use of property rights in resource allocation are investigated. It is argued that the recreational sector needs better definition of its claim for priority access to resources.  相似文献   

Method of auxiliary sources for calculating the magnetic and electric fields induced in a layered Earth     

《Journal of Atmospheric and Solar》2003,65(10):1151-1160

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On the linear elastic responses of the 2D bonded discrete element model     

Gao-Feng Zhao  Qiuyue Yin  Adrian R. Russell  Yingchun Li  Wei Wu  Qin Li 《国际地质力学数值与分析法杂志》2019,43(1):166-182

The bonded discrete element model (DEM) is a numerical tool that is becoming widely used when studying fracturing, fragmentation, and failure of solids in various disciplines. However, its abilities to solve elastic problems are usually overlooked. In this work, the main features of the 2D bonded DEM which influence Poisson's ratio and Young's modulus, and accuracy when solving elastic boundary value problems, are investigated. Outputs of numerical simulations using the 2D bonded DEM, the finite element method, a hyper elasticity analysis, and the distinct lattice spring model (DLSM) are compared in the investigation. It is shown that a shear interaction (local) factor and a geometric (global) factor are two essential elements for the 2D bonded DEM to reproduce a full range of Poisson's ratios. It is also found that the 2D bonded DEM might be unable to reproduce the correct displacements for elastic boundary value problems when the represented Poisson's ratio is close to 0.5 or the long-range interaction is considered. In addition, an analytical relationship between the shear stiffness ratio and the Poisson's ratio, derived from a hyper elasticity analysis and applicable to discontinuum-based models, provides good agreement with outputs from the 2D bonded DEM and DLSM. Finally, it is shown that the selection of elastic parameters used the 2D bonded DEM has a significant effect on fracturing and fragment patterns of solids.  相似文献   

Climate change impact assessment on flow regime by incorporating spatial correlation and scenario uncertainty     

Vallam  P.  Qin  X. S. 《Theoretical and Applied Climatology》2017,129(1-2):607-622

Flooding risk is increasing in many parts of the world and may worsen under climate change conditions. The accuracy of predicting flooding risk relies on reasonable projection of meteorological data (especially rainfall) at the local scale. The current statistical downscaling approaches face the difficulty of projecting multi-site climate information for future conditions while conserving spatial information. This study presents a combined Long Ashton Research Station Weather Generator (LARS-WG) stochastic weather generator and multi-site rainfall simulator RainSim (CLWRS) approach to investigate flow regimes under future conditions in the Kootenay Watershed, Canada. To understand the uncertainty effect stemming from different scenarios, the climate output is fed into a hydrologic model. The results showed different variation trends of annual peak flows (in 2080–2099) based on different climate change scenarios and demonstrated that the hydrological impact would be driven by the interaction between snowmelt and peak flows. The proposed CLWRS approach is useful where there is a need for projection of potential climate change scenarios.

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An overview of the role of the Global Environment Facility in international waters with reference to marine capacity building     

《Marine Policy》1998,22(3):235-246

This paper provides a brief overview of the development of the Global Environment Facility (GEF) since its creation in June 1991 and the nature of its activities in the field of International Waters. Whilst it is recognised that the GEF represents the single largest source of international financial assistance for achieving global environmental benefits its investment in International Waters remains comparatively small. Since the GEF is designed to achieve global environmental benefits through provision of grant and concessionary funding for the agreed incremental costs of projects its primary objective is not capacity building. Nevertheless, the need for capacity building at the individual and institutional levels within projects was recognised early during the initiation of GEF activities. More recently the need for programmatic approaches to capacity building within the GEF has been identified and is being addressed. It is suggested that potentially the role of the GEF in environmental and marine capacity building could be most important at a global, system-wide level, in terms of testing and promoting innovative and novel approaches to issues of environmentally sound and sustainable economic development.  相似文献   

数据银行技术在物探数据管理中的应用现状   总被引：1，自引：0，他引：1  

张绍红  王永江  刘司红 《物探与化探》1999,23(3):221-226

随着石油勘探开发的发展,要求人们从大量的新、旧资料中快速获取有用的信息.数据银行技术给用户提供了一个高性能的存贮管理系统,提供更安全的快速联机访问,可以大幅度降低存贮、维护资料成本,节省寻找资料时间,帮助地学家更好地作出决策.它提供了一个经济而有竞争力的服务.本文对数据银行技术的有关方面进行了简要的综述.  相似文献   

Inhibition of calcium carbonate precipitation in NaCl brines from 25 to 90°C     

《Applied Geochemistry》1999,14(1):17-25

The nucleation induction period of CaCO₃ in NaCl brines in the absence and presence of scale inhibitors was experimentally measured at temperatures from 25 to 90°C. A semi-empirical mathematical inhibitor model is presented for the CaCO₃ scale control in industrial processes based upon nucleation theory and experimental observations. Results show that the minimum inhibitor dosage (C_inh) may be obtained from: C_inh=f(s)/b_inh log [t_inh/t₀], where t_inh is the inhibition time, e.g., 20 min, t₀ is the nucleation induction period in the absence of inhibitors, b_inh is the inhibitor efficiency, and f(s) is the safety factor, e.g., 2. Important factors for the kinetics of both nucleation and inhibition have been incorporated in this model including the calcite saturation index (SI), temperature (T), and the molar ratio of Ca to HCO₃ alkalinity (R). In this paper, model parameters are presented for commonly used inhibitors, including 1-hydroxyethylidene-1,1-diphosphonic-acid (HEDP) and nitrilotri(methylene phosphonic) acid (NTMP). Results show that HEDP and NTMP are the best inhibitors for calcite scaling in the systems examined.  相似文献   

Origin of vesicle layering and double imbrication by endogenous growth in the Birkett basalt flow (Columbia river plateau)     

《Journal of Volcanology and Geothermal Research》1999,88(1-2):15-28

The 40-m thick Birkett basalt pahoehoe flow at Sentinel Gap in the Columbia River Plateau has an unusually thick (≥15 m) upper vesicular zone. This zone includes a striking layering in which the layers have contrasted vesicle abundances and sizes. Most layers show a reverse grading of vesicle size and abundance. The layering is interpreted to have grown endogenously by the cyclic injection of vesicular lava layers under the growing top crust, accommodated by uplift of that crust. Grading of the layers resulted from vesicle growth and ascent. Each injection occurred at or near the boundary between vesicular and non-vesicular lava of the preceding layer and split that layer into an upper vesicular part and a lower non-vesicular part. Critical to this interpretation are (1) a pervasive foliation and lineation, defined by the parallelism of strongly flattened and elongate vesicles, transects the vesicle layers obliquely; and (2) the magnetic fabric (the anisotropy of magnetic susceptibility) is oriented similarly to the vesicle foliation, and also defines a cryptic foliation in the non-vesicular zone having a dip opposed to that in the layered zone. These foliations are interpreted to be opposed imbrications and indicate the flow azimuth of the lava. They strongly support the concept of lava growth by successive thin sill-like insertions of fresh vesicular lava between hot but static and effectively solid floor and roof.  相似文献   

Radio occultation data analysis by the radioholographic method     

《Journal of Atmospheric and Solar》1999,61(15):1169-1177

The radioholographic method is briefly described and tested by using data of 4 radio occultation events observed by the GPS/MET experiment on 9 February 1997. The central point of the radioholographic method (Pavelyev, 1998) is the generation of a radiohologram along the LEO satellite trajectory which allows the calculation of angular spectra of the received GPS radio wave field at the LEO satellite. These spectra are promising in view of detection, analysis and reduction of multipath/diffraction effects, study of atmospheric irregularities and estimation of bending angle error. Initial analysis of angular spectra calculated by the multiple signal classification (MUSIC) method gives evidence that considerable multibeam propagation occurs at ray perigee heights below 20 km and at heights around 80–120 km for the 4 GPS/MET occultation events. Temperature profiles obtained by our analysis (radioholographic method, Abel inversion) are compared with those of the traditional retrieval by the UCAR GPS/MET team (bending angle from slope of phase front, Abel inversion). In 3 of 4 cases we found good agreement (standard deviation σ_T∼1.5°K between both retrievals at heights 0–30 km).  相似文献   

Geochemical factors controlling free Cu ion concentrations in river water     

《Geochimica et cosmochimica acta》1999,63(19-20):3311-3319

Copper speciation was determined monthly at seven sites on four rivers in southern New England to understand which geochemical factors control free metal ion concentrations in river water. Samples were conventionally filtered (<0.45 μm) and then ultrafiltered (3.000 molecular weight cut-off) to determine Cu speciation in the truly dissolved size fraction. Differential pulse anodic stripping voltammetry (DPASV) was used to quantify natural organic complexation and cathodic stripping square wave voltammetry (CSSWV) to measure directly both Cu sulfide complexes and total EDTA concentrations. The results showed both dissolved organic matter (DOM) and sulfide complexation dominate Cu speciation and control the concentrations of free ion. Free Cu²⁺ was calculated to be in the subnanomolar range for the majority of the year. Only in the winter months, when concentrations of DOM and metal sulfides complexes were at a minimum were free metal ions directly measurable by DPASV at low nanomolar concentrations. The extent of sulfide complexation appears to be dominated by the size of headwater marshes (upstream sampling sites) and by the amount of sewage treatment plant effluent (downstream sites). DOM complexation was related to the organic matter composition and followed model organic ligands. Indirect evidence suggests variations in river water pH and Ca²⁺ (metal competition) has only a minor role in Cu complexation. Measured concentrations of total EDTA suggest this synthetic ligand can control Cu speciation in some highly developed watersheds; however, competition from Ni (and possibly Fe) limits the extent of this complexation.  相似文献