Application of the Ordered Weighted Averaging (OWA) method to the Caspian Sea conflict   总被引：1，自引：0，他引：1  

Hojjat Mianabadi  Majid Sheikhmohammady  Erik Mostert  Nick Van de Giesen 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(6):1359-1372

This study proposes a promising allocation mechanism of the Caspian Sea natural resources, which are presently shared among five countries. To date, these nations have been unable to reach an allocation agreement. We apply a methodology to propose the most appropriate solution under different risk attitudes of the states. This research is different from other studies regarding the Caspian Sea negotiations in that it employs risk-based fuzzy multi attribute decision making methods for simulating the risk attitudes or optimism/pessimism degrees of the decision makers. The ordered weighted averaging (OWA) approach, which considers the optimism/pessimism degree quantitatively, is used to take into account the effects of different risk attitudes of the negotiators on the final outcome. We demonstrate how one could obtain a range of alternatives under different multi attribute and risk attitudes. The induced OWA (IOWA) method is also used to determine the relative power of these states bordering the Caspian Sea by considering several attributes, including different risk attitudes of agents. Results indicate that taking into account the risk attitude (prone, neutral, averse) of the states can affect the overall ranking of the proposed solutions. The findings from this study may facilitate negotiation regarding the most preferred allocation mechanism for the Caspian Sea.  相似文献   

Alternative water management options to reduce vulnerability for climate change in the Netherlands   总被引：1，自引：0，他引：1  

Rutger de Graaf  Nick van de Giesen  Frans van de Ven 《Natural Hazards》2009,51(3):407-422

Urbanization, land subsidence and sea level rise will increase vulnerability of the urbanized low-lying areas in the western part of the Netherlands. In this article possibilities are explored to reduce vulnerability of these areas by implementing alternative water management options. Two main water management fields are distinguished, water supply and flood control. A four-component vulnerability framework is presented that includes threshold capacity, coping capacity, recovery capacity, and adaptive capacity. By using the vulnerability framework it is shown that current water supply and flood control strategies in the Netherlands focus on increasing threshold capacity by constructing higher and stronger dikes, improved water storage and delivery infrastructure. A complete vulnerability decreasing strategy requires measures that include all four capacities. Flood damage reduction, backup water supply systems and emergency plans are measures that can contribute to increasing coping capacity. Recovery capacity can be increased by multi-source water supply, insurance, or establishing disaster funds. Adaptive capacity can be developed by starting experiments with new modes of water supply and urbanization. Including all four components of the vulnerability framework enables better understanding of water and climate related vulnerability of urban areas and enables developing more complete water management strategies to reduce vulnerability.  相似文献   

Magnitude and frequency of grain flows on a desert sand dune     

Carrie Breton  Nicholas Lancaster  William G. Nickling 《Geomorphology》2008,95(3-4):518-523

Preliminary studies of the magnitude and frequency of lee side avalanches (grain flows) on a Namib crescentic dune show that the frequency of grain flows for a given segment of the lee face is dependent on the wind speed and sand transport rate for the period preceding their initiation; and the magnitude of the flows as described by their area is inversely proportional to the interval between flows and thus wind speed and sand transport rates. These studies indicate the potential of using a simple digital video camera technique to document the magnitude, frequency and geometry of grain flows on desert sand dunes.  相似文献   

Analyses on granular mass movement mechanics and deformation with distinct element numerical modeling: implications for large-scale rock and debris avalanches     

Nick Thompson  Matthew R. Bennett  Nick Petford 《Acta Geotechnica》2009,4(4):233-247

A large-scale avalanche of Earth material is modeled here as a granular flow using a distinct element numerical model PFC ^2D. Such failures occur in a variety of geological settings and are known to occur frequently over geologic time-scales transporting significant volumes of material basinward. Despite this, they remain poorly understood. The model used here begins with a listric failure, typical of the flank collapse of a volcanic cone, and describes the movement of an assembly of several thousand particles from failure to deposition. Within the model, each particle possesses its own material properties and interacts with its immediate neighbors and/or the basal boundary during emplacement. The general mechanics of the particle assembly are observed by monitoring the stresses, displacements, and velocities of distinct sections of the avalanche body. We monitor the avalanches’ energy regime (e.g., gravitational influence, energy dissipation by friction, kinetic energy evolution, and avalanche body strain). The addition of colored markers of varying geometry to the pre-failure avalanche was also used to make qualitative observations on the internal deformation that occurs during avalanche emplacement. A general stretching and thinning of the avalanche is observed. Monitoring of vertical and horizontal variations in stress, strain, porosity, and relative particle stability indicate that the lower more proximal sections of the avalanche are subject to higher stresses. These stresses are observed to be most significant during the initial phases of failure but decline thereafter; a situation likely to be conducive to block fragmentation and in developing a basal shear layer in real-world events. The model also shows how an avalanche which is initially influenced purely by gravity (potential energy) develops into a fully flowing assemblage as downslope momentum is gained and kinetic energy increases. The horizontal transition where the failure meets the run-out surface is recognized as a key area in emplacement evolution. The model has particular relevance to volcanic flank collapses and consequently the implications of the model to these types of failure and the geological products that result are considered in detail although the model is relevant to any form of large-scale rock or debris avalanche.  相似文献   

Discussion of “Neuro-fuzzy models employing wavelet analysis for suspended sediment concentration prediction in rivers”     

Robert J. Abrahart  Nick J. Mount 《水文科学杂志》2013,58(7):1325-1329

Citation Abrahart, R.J. & Mount, N.J. (2011) Discussion of “Neuro-fuzzy models employing wavelet analysis for suspended sediment concentration prediction in rivers by S.A. Mirgagheri et al. (2010, Hydrol. Sci. J. 55(7), 1175–1189).” Hydrol. Sci. J. 56(7), 1325–1329.  相似文献   

Large roughness element effects on sand transport,Oceano Dunes,California     

John A. Gillies  Nicholas Lancaster 《地球表面变化过程与地形》2013,38(8):785-792

The effect of large roughness elements on sand transport efficiency was evaluated on a coastal sand sheet by measuring sand flux with two types of sand traps [Big Spring Number Eight (BSNE) and the Cox Sand Catcher (CSC)] at 30 positions through a 100 m‐long × 50 m‐wide roughness array comprised of 210 elements each with the dimensions 1·17 m long × 0·4 m high × 0·6 m wide. The 210 elements were used to create a roughness density (λ) of 0·022 (λ = n bh/S, where n is the number of elements, b the element breadth, h the element height, and S is the area of the surface that contains all the elements) in an area of 5000 m². The mean normalized saltation flux (NSF) values (NSF = outgoing sand flux/incoming sand flux) at the furthest downwind distance for the two trap types were 0·44 and 0·41, respectively. This is in excellent agreement with an empirical model prediction of 0·5. The reduction in saltation flux is similar to an earlier separate study for an equivalent λ composed of elements of similar height (0·36 m), even though the roughness element forms were different (rectangular in this study as opposed to circular) as were the horizontal porosity of the arrays (49% versus 16%). This corroborates earlier results that roughness element height is a critical parameter that enhances reduction in sand transport by wind for similar λ configurations. The available data suggest the form of the relationship between transport reduction efficiency and height is likely a power relationship with two limiting conditions: (1) for elements ≤ 0·1 m high the effect is minimized, and (2) as element height matches and then exceeds the maximum height of the saltation layer (≥ 1 m), the effect will stabilize near a maximum of NSF ≈ 0·32. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The Seasonal Prediction of the Exceptional Yangtze River Rainfall in Summer 2020     

Chaofan LI  Riyu LU  Nick DUNSTONE  Adam A.SCAIFE  Philip E.BETT  Fei ZHENG 《大气科学进展》2021,38(12):2055-2066

During June and July of 2020, the Yangtze River basin suffered from extreme mei-yu rainfall and catastrophic flooding. This study explores the seasonal predictability and associated dynamical causes for this extreme Yangtze River rainfall event, based on forecasts from the Met Office GloSea5 operational forecast system. The forecasts successfully predicted above-average rainfall over the Yangtze River basin, which arose from the successful reproduction of the anomalous western North Pacific subtropical high (WNPSH). Our results indicate that both the Indian Ocean warm sea surface temperature (SST) and local WNP SST gradient were responsible for the westward extension of the WNPSH, and the forecasts captured these tropical signals well. We explore extratropical drivers but find a large model spread among the forecast members regarding the meridional displacements of the East Asian mid-latitude westerly jet (EAJ). The forecast members with an evident southward displacement of the EAJ favored more extreme Yangtze River rainfall. However, the forecast Yangtze River rainfall anomaly was weaker compared to that was observed and no member showed such strong rainfall. In observations, the EAJ displayed an evident acceleration in summer 2020, which could lead to a significant wind convergence in the lower troposphere around the Yangtze River basin, and favor more mei-yu rainfall. The model forecast failed to satisfactorily reproduce these processes. This difference implies that the observed enhancement of the EAJ intensity gave a large boost to the Yangtze River rainfall, hindering a better forecast of the intensity of the event and disaster mitigation.  相似文献   

Changes in daily climate extremes in China and their connection to the large scale atmospheric circulation during 1961–2003     

Qinglong You  Shichang Kang  Enric Aguilar  Nick Pepin  Wolfgang-Albert Flügel  Yuping Yan  Yanwei Xu  Yongjun Zhang  Jie Huang 《Climate Dynamics》2011,36(11-12):2399-2417

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Relationship among titanium,rare earth elements,U–Pb ages and deformation microstructures in zircon: Implications for Ti-in-zircon thermometry     

Nick E. Timms  Peter D. Kinny  Steven M. Reddy  Katy Evans  Chris Clark  Dave Healy 《Chemical Geology》2011,280(1-2):33-46

A zircon grain in an orthopyroxene–garnet–phlogopite–zircon–rutile-bearing xenolith from Udachnaya, Siberia, preserves a pattern of crystallographic misorientation and subgrain microstructure associated with crystal–plastic deformation. The zircon grain records significant variations in titanium (Ti) from 2.6 to 30 ppm that corresponds to a difference in calculated Ti-in-zircon temperatures of over several hundred degrees Celsius. The highest Ti concentration is measured at subgrain centres (30 ppm), and Ti is variably depleted at low-angle boundaries (down to 2.6 ppm). Variations in cathodoluminescence coincide with the deformation microstructure and indicate localised, differential enrichment of rare earth elements (REE) at low-angle boundaries. Variable enrichment of U and Th and systematic increase of Th/U from 1.61 to 3.52 occurs at low-angle boundaries. Individual SHRIMP-derived U–Pb ages from more deformed zones (mean age of 1799 ± 40, n = 22) are systematically younger than subgrain cores (mean age of 1851 ± 65 Ma, n = 7), and indicate that open system behaviour of Ti–Th–U occurred shortly after zircon growth, prior to the accumulation of significant radiogenic Pb. Modelling of trace-element diffusion distances for geologically reasonable thermal histories indicates that the observed variations are ~ 5 orders of magnitude greater than can be accounted for by volume diffusion. The data are best explained by enhanced diffusion of U, Th and Ti along deformation-related fast-diffusion pathways, such as dislocations and low-angle (< 5°) boundaries. These results indicate chemical exchange between zircon and the surrounding matrix and show that Ti-in-zircon thermometry and U–Pb geochronology from deformed zircon may not yield information relating to the conditions and timing of primary crystallisation.  相似文献   

New friends in new places: Network formation during the migration process among Poles in the UK   总被引：1，自引：0，他引：1  

Nick Gill  Paula Bialski 《Geoforum》2011,42(2):241-249

This paper contributes to on-going work that seeks to understand the dynamic nature of immigrant social network formation. We explore three propositions, derived from the literature, that might be expected to characterise the ways in which migrant associational ties evolve during and immediately after arrival in their destination country. Evidence is drawn from 42 interviews conducted between January and December 2008 with predominantly Polish migrants to the UK (28) as well as domestic service providers (14). In agreement with the existing literature on immigrant social network formation we find that weak associational ties between migrants are locally dense and rapidly formed. More surprisingly, we also find that the Poles in our sample from lower socio-economic groups tended to rely heavily upon weak associational ties while higher socio-economic group Poles tended to rely on associations made through their employing institutions. This illustrates the importance of socio-economic status in framing co-ethnic migrant network formation. This is significant because we also find that weak associational ties are not unambiguously beneficial to lower socio-economic group migrants who tend to (have to be) more compromising about, and therefore more compromised by, the social ‘friendships’ that result.  相似文献