Development of ground-shaking maps for the Sultanate of Oman   总被引：1，自引：1，他引：0  

Eser Çaktı  Issa El-Hussain  Karin Şeşetyan  Ahmed Deif  Ufuk Hancılar  Ghazi Al-Rawas  Yaver Kamer  Khalifa Al-Jabri 《Natural Hazards》2016,82(2):1357-1373

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Food utilisation by coastal fish assemblages in rocky and soft bottoms on the Swedish west coast: Inference for identification of essential fish habitats   总被引：1，自引：1，他引：1  

Johan Stl  Leif Pihl  Hkan Wennhage 《Estuarine, Coastal and Shelf Science》2007,71(3-4):593-607

The concept of essential fish habitats (EFHs) is widely accepted for conservational and management purposes. EFHs are often considered as high quality habitats for fisheries species and subsequently of high values for society. In this study, fish and Substrate-Associated Prey (SAP) were sampled during the productive summer season 1998 (fish) and 2003 and 2004 (SAP) in shallow coastal rocky- and soft-bottom habitats on the Swedish west coast. The aim was to study the spatial and monthly variation of SAP as well as abundance and biomass of fish, and to examine if food items found in the diet of the fish assemblage were derived from SAP. We also examined if the diet of Ctenolabrus rupestris, a resident and abundant fish species in the shallow coastal habitats, and the diet of four seasonally abundant and commercially important fish species (Gadus morhua, Pleuronectes platessa, Salmo trutta and Scomber scombrus) were derived from SAP. There were significantly higher mean species number and abundance of the SAP assemblage on rocky compared to soft bottoms and the highest values were found on the rocky bottoms in August and in the shallowest (0–3 m) depth strata. There were no significant differences in number of fish species caught in the two habitats, although mean number of fish and mean biomass were significantly higher on rocky bottoms. Both habitats showed the same seasonal variation and the highest values of number of fish species, abundance and biomass were observed in June. On rocky bottoms, gastropods and amphipods were the most frequent food items in the diet of the entire fish assemblage and these items were also the most abundant SAP in this habitat. The dominant food items of the soft-bottom fish assemblage were decapods and fish, which were not common SAP. However, except for S. scombrus, the diet of the selected fish species showed a strong association to the SAP availability. Gadus morhua displayed the strongest association to SAP on rocky bottoms and P. platessa and C. rupestris to SAP on soft bottoms. Further, for C. rupestris, multivariate statistical analysis showed a significant association to the SAP assemblage on both rocky and soft bottoms. These results provide vital new information for the management and conservation of Essential Fish Habitats on the Swedish west coast.  相似文献   

Superficial deep-water sediments of the Eastern Marmara Basin     

G. Evans  H. Erten  S. N. Alavi  H. R. Von Gunten  M. Ergin 《Geo-Marine Letters》1989,9(1):27-36

Superficial sediments (top Im) of the Eastern Mediterranean Basin, Sea of Marmara, Turkey accumulated rapidly (0.087 ± 0.012 g/cm² · y) by hemipelagic sedimentation with only limited amounts of gravity flow or bottom current action under low oxygenated but not anoxic conditions. They have restricted faunas, relatively higher organic carbon (1–1.8%) and lower calcium carbonate (14–20%) contents than other Eastern Mediterranean Basin sediments. Sedimentation shows little change over the last millenium except for an increase in Cu, Zn, Pb, Cr, and P over the last few centuries. The increase was most likely caused by increased metallurgical activities since the eighteenth century but are not at sufficient levels for the area to be regarded as polluted.  相似文献   

Major flare effects on the intensity of the green corona and geomagnetic activity     

Levent Altaş 《Earth, Moon, and Planets》1989,46(2):127-134

The effects of the solar major flares indicated by the intensive radio bursts, high velocity streams or shock waves, coronal and ionospheric disturbances on the geomagnetic and coronal activities are investigated during the near the maximum phase of 21st solar cycle, in detail. The significant and the weak increases in the level of the geomagnetic and coronal activities indices were observed, respectively, after the occurrence of these events.  相似文献   

A simultaneous spectroscopic and photometric study of two eclipsing binaries: V566 Oph and V972 Her     

S. O. Selam  E. M. Esmer  H. V. Şenavcı  E. Bahar  O. Yörükoğlu  M. Yılmaz  Ö. Baştürk 《Astrophysics and Space Science》2018,363(2):34

In this study, we have performed simultaneous solutions of light and radial velocity curves of two eclipsing binary systems, V566 Oph and V972 Her. We observed both systems spectroscopically with a very recently installed spectrograph on the 40 cm telescope, T40, located in Ankara University Kreiken Observatory (AUKR), for the first time. We made use of the photometric data from the Hipparcos satellite for V972 Her, while we obtained the photometric observations of V566 Oph by using the 35 cm telescope, T35, located also in our observatory campus. We derived the absolute parameters for both systems and discussed their evolutionary states. In addition to the simultaneous analysis, we have also analyzed the change in mid-eclipse times for V566 Oph, and found cyclic variations, for which we have discussed light-time effect and magnetic activity as their potential origin, superimposed on a secular change due to a mass transfer between the components of the binary.  相似文献   

Design weight of armour stone considering the effect of extreme waves     

Berguzar Oztunali Ozbahceci  Aysen Ergin 《Ocean Engineering》2008,35(3-4):393-399

In this study, waves with the heights higher than H_1/3 in an irregular wave train are called as extreme waves and defined with the help of extreme wave parameter, α_extreme. In order to see the effect of extreme waves on the design weight of armour stone, stability analysis is carried out based on the hydraulic model test results. The test results of high α_extreme cases (HE) and low α_extreme cases (LE) are compared with currently used van der Meer's formulae with permeability factor P=0.4 and 0.45 and Hudson formula by using H_1/3 and H_1/10 in terms of the design weight of armour stone. As a result of the comparison, it is found that Hudson formula by using H_1/3 underestimates the necessary armour weight. Usage of H_1/10 instead of H_1/3 in Hudson formula doubles the weight which seems overestimated when Irribaren number is away from the transition zone in which both wave run-up and run-down forces become effective. However, it seems underestimated near the transition zone where experiment case HE gives higher armour weights. When the design weight of armour stone is calculated by van der Meer's formulae with P=0.4, it may be necessary to increase the weight up to 30% in the case of high extreme waves. On the other hand, van der Meer's formulae may overestimate the weight 14% when the extreme waves are low.  相似文献   

基于POI数据的上海市餐饮业空间分布特征及影响因素   总被引：2，自引：0，他引：2  

唐锦玥  何益珺  塔娜 《热带地理》2020,40(6):1015-1025

以上海市为研究对象，基于兴趣点（POI）数据，运用核密度分析刻画餐饮业空间格局，并构建OLS模型、空间滞后模型、空间误差模型探究餐饮业空间分布的影响因素。结果发现，餐饮业空间分布呈块状聚集、多中心发展的格局。其中，西餐业高度集中于内环线以内，呈东西向延伸；快餐业在中心城区和高校集聚的城郊结合部大规模集聚。空间计量回归结果表明，餐饮业分布受到人口、经济、交通、空间4类要素的影响：区域经济发展水平高、人口规模大、交通优越、相关业态丰富会促进集聚，而周边业态的混合度过高则会抑制集聚，城市空间结构也会影响餐饮业分布，商圈、中心城区的餐饮业密度更高；中餐、西餐、正餐、快餐4类餐饮业分布的影响因素存在差异性，西餐企业倾向于分布在地价较高的地区，中餐企业对交通可达性有更高的需求，正餐企业的分布与当地区域经济发展水平显著相关，快餐企业的分布与各类文娱公共设施的分布有密切联系。  相似文献   

Fisher's behaviour with individual vessel quotas—Over-capacity and potential rent: Five case studies     

Frank Asche  Hkan Eggert  Eyjolfur Gudmundsson  Ayoe Hoff  Sean Pascoe 《Marine Policy》2008,32(6):920-927

Internationally, individual vessel quotas (IVQ) have become an increasingly popular management tool. The main attraction of IVQs is the incentives they create for cost savings, autonomous capacity adjustment and, subsequently, rent generation. In this paper, the extent to which different IVQ systems have facilitated resource rent generation and capacity adjustment in five European countries—Denmark, Iceland, Norway, Sweden and the UK—is examined. The potential economic rents and the capacity reduction necessary to achieve these rents in each of the fisheries are also estimated. Reasons why IVQs have not achieved their potential economic benefits in these fisheries are also examined.  相似文献   

Stream flow forecasting using neuro‐wavelet technique     

Özgür Kişi 《水文研究》2008,22(20):4142-4152

This paper proposes the application of a neuro‐wavelet technique for modelling monthly stream flows. The neuro‐wavelet model is improved by combining two methods, discrete wavelet transform and multi‐layer perceptron, for one‐month‐ahead stream flow forecasting and results are compared with those of the single multi‐layer perceptron (MLP), multi‐linear regression (MLR) and auto‐regressive (AR) models. Monthly flow data from two stations, Gerdelli Station on Canakdere River and Isakoy Station on Goksudere River, in the Eastern Black Sea region of Turkey are used in the study. The comparison results revealed that the suggested model could increase the forecast accuracy and perform better than the MLP, MLR and AR models. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Downstream fining in contrasting reaches of the sand‐bedded Yellow River     

Wanquan Ta  Haibin Wang  Xiaopeng Jia 《水文研究》2011,25(24):3693-3700

Compared to downstream fining of a gravel‐bedded river, little field evidence exists to support the process of downstream fining in large, fine sand‐bedded rivers. In fact, the typically unimodal bed sediments of these rivers are thought to produce equal mobility of coarse and fine grains that may discourage downstream fining. To investigate this topic, we drilled 200 sediment cores in the channel beds of two fine‐grained sand‐bedded reaches of the Yellow River (a desert reach and a lower reach) and identified a fine surface layer (FSL) developed over a coarse subsurface layer (CSL) in the 3‐m‐thick bed deposits. In both reaches downstream, the thickness of the FSL increased, while that of the CSL decreased. Comparison of the depth‐averaged median grain sizes of the CSL and the FSL separately in both reaches shows a distinct downstream fining dependence to the median grain size, which indicates that at a large scale of 600‐800 km, the CSL shows a significant downstream fining, but the FSL shows no significant trends in downstream variations in grain size. This result shows that fine sediment supply (<0·08 mm median grain size) from upstream, combined with lateral fine sediment inputs from tributaries and bank erosion, can cause a rapid fining of the downstream channel bed surface and can develop the FSL layer. However, in the desert reach, lateral coarse sediment supply (>0·08 mm median grain size) from wind‐borne sediments and cross‐desert tributaries can interrupt the FSL and coarsen the channel bed surface locally. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献