Comparison of simultaneous and combinatorial auction designs in fisheries quota market     

M.S. Iftekhar  J.G. Tisdell 《Marine Policy》2012,36(2):446-453

Individual transferable quota (ITQ) markets are being used successfully to distribute quotas in single region and single species fisheries. In many parts of the world, the development of well crafted markets for multispecies or multiregional fisheries is still evolving. As a result, there exists an opportunity to inform policy by providing research insights into the relative merits of alternative market designs for such fisheries.This study explored the relative merits of a simultaneous ascending auction design and an iterative combinatorial auction design for a hypothetical multiple region quota market. In a simultaneous auction, separate auctions are run in parallel for individual species or regions. During intermediate rounds, fishers can adjust their bids in auction depending on their position in the other auction. In a combinatorial auction, a fisher can purchase a combination of quotas (or a package quota) for different fish species or regions in the same auction. Being able to acquire bundles of species or regions allows fishers to take advantage of complementarities. To date, the potentials of such auctions have not been thoroughly tested in fisheries quota markets. This study found that while a simultaneous auction design was more efficient than combinatorial auction design overall, combinatorial market design took fewer rounds to make final allocations and performed better in high synergy environments.  相似文献   

基于耦合标势与矢势的有限体积法模拟非均匀各向异性地层中多分量感应测井三维响应   总被引：8，自引：8，他引：0       下载免费PDF全文

张烨  汪宏年  陶宏根  杨守文 《地球物理学报》2012,55(6):2141-2152

为快速有效地研究、考察各向异性地层条件下多分量感应测井的响应特征,本文利用电场标势与矢势的有限体积法研制出三维频率域电磁场响应的数值模拟算法,克服由低频发射或高阻地层产生的低感应数问题,有效提高了三维电磁数值模拟算法的应用范围和计算效率.首先利用电场的标势与矢势将Maxwell方程转化为满足库仑规范条件的耦合势Helmholtz方程,以Yee氏交错非均匀网格中不同位置上的节点为中心建立四种控制体积单元,通过对控制体积单元中电磁场与电导率的积分平均实现耦合势方程和磁偶极子旋度的离散,并得到一个对角占优的大型稀疏复线性代数方程组,然后,通过不完全LU分解预处理和稳定双共轭梯度法快速求解离散方程.数值结果证明了该算法的有效性,并进一步考查了仪器偏心、倾斜井、垂直裂缝等复杂条件下多分量感应的响应特征.  相似文献   

Effective dispersion in conditioned transmissivity fields     

《Advances in water resources》2014

We analyze the impact of conditioning to measurements of hydraulic transmissivity on the transport of a conservative solute. The effects of conditioning on solute transport are widely discussed in the literature, but most of the published works focuses on the reduction of the uncertainty in the prediction of the plume dispersion. In this study both ensemble and effective plume moments are considered for an instantaneous release of a solute through a linear source normal to the mean flow direction, by taking into account different sizes of the source. The analysis, involving a steady and spatially inhomogeneous velocity field, is developed by using the stochastic finite element method. Results show that conditioning reduces the ensemble moment in comparison with the unconditioned case, whereas the effective dispersion may increase because of the contribution of the spatial moments related to the lack of stationarity in the flow field. As the number of conditioning points increases, this effect increases and it is significant in both the longitudinal and transverse directions. Furthermore, we conclude that the moment derived from data collected in the field can be assessed by the conditioned second-order spatial moment only with a dense grid of measured data, and it is manifest for larger initial lengths of the plume. Nevertheless, it seems very likely that the actual dispersion of the plume may be underestimated in practical applications.  相似文献   

CT扫描技术在微观驱替实验及剩余油分析中的应用     

曹永娜 《CT理论与应用研究》2015,24(1):47-56

CT扫描技术不仅可以重建不同驱替液在不同驱替时刻的微观剩余油分布图像,而且通过X射线衰减系数换算成CT值,还可以计算岩心的孔隙度和含油饱和度参数,从而对实验岩心的非均质性和每一驱替过程不同驱替时刻的微观剩余油进行定量分析。分析认为实验岩心在不同驱替阶段微观剩余油类型之间存在量的转化。   相似文献   

Plane symmetric inhomogeneous cosmological models with a perfect fluid in General Relativity II     

Anirudh Pradhan  Anju Rai 《Astrophysics and Space Science》2008,314(1-3):225-229

We investigate a class of solutions of Einstein equations for the plane symmetric perfect fluid case. If these solutions have shear, they must necessarily be non-static. Some physical and geometric properties of the models are also discussed.   相似文献   

地震断裂系统的分形和在地震预报中的应用          下载免费PDF全文

姚立珣  虞雪君 《地震工程学报》1993,15(3):25-32,37

本文基于地震断层具有自相似结构,从分形概念出发,依据地震资料提出了适合于前震和余震的分形模型,在此基础上讨论了前震和余震的b值特征,提出了地震矩不均衡度的概念。本文还探讨了利用分数维和地震矩不均衡度进行地震预报的可能性。研究发现,正常情况下,地震矩不均衡度呈现低值,大震发生前出现高值异常,震后降低;在空间上,震前2—4年其异常范围大,震前一年异常区逐渐缩小,大震发生在异常集中区内或其边缘。  相似文献   

非均匀电磁波在导电媒质界面反射的横向偏移   总被引：7，自引：2，他引：5  

刘福平  李瑞忠  杨长春  张红梅  陈辉国  王安玲  高杰 《地球物理学报》2006,49(2):533-539

由电磁场边值关系给出了非均匀电磁波在导电媒质界面反射时反射系数所产生的附加相角. 利用这一附加相角导出了非均匀电磁波在导电介质界面的横向偏移,并进行了横向偏移的相关计算,绘出了横向偏移随入射角的变化曲线. 结果表明：在导电媒质界面反射电磁波的横向偏移随入射角的增大而增大,当入射角接近90°时,电磁波在界面要传播较长时间后才返回第一种媒质. 在同一入射角电场偏振化方向在入射面的电磁波要比电场偏振化方向垂直于入射面的电磁波的横向偏移大,随着电磁波频率的增加横向偏移变小.  相似文献   

烟台夹河口外柱状沉积物还原性无机硫、活性铁的变化特征及其相互关系     

姜明  赵国强  李兆冉  盛彦清 《海洋科学》2018,42(8):90-97

海洋沉积物中还原性无机硫和活性铁的地球化学过程与沉积物环境质量演变密切相关。本研究利用改进的冷扩散法和盐酸萃取法分别对烟台夹河口北部海域深约4 m的柱状沉积物中的酸性可挥发硫(AVS)、黄铁矿硫(CRS)、元素硫(ES)和活性铁(FeⅡ和FeⅢ)进行了测定,并从地球化学机理方面探讨了硫与铁的分布特征及其耦合机制。结果表明,烟台夹河口北部近海深层柱状沉积物中还原性无机硫以CRS为主,其次是AVS和ES,其中AVS含量垂向分布较均匀,而CRS和ES含量在垂向上呈表层和底层高,中间层低的趋势;活性铁以Fe(Ⅱ)为主,其随深度增加而增加,Fe(Ⅲ)随深度逐渐降低,大部分Fe(Ⅲ)被还原为溶解态的Fe(Ⅱ),并且与硫酸盐还原产生的H_2S相结合生成CRS和ES,导致CRS和ES在柱状沉积物底部积累;同时研究表明,较低的硫化度和矿化度,活性铁不是还原性无机硫累积的限制因子。  相似文献   

Two-dimensional continuous wavelet transform of simulated spatial images of waves on a slowly varying topography   总被引：1，自引：0，他引：1  

Laurence Zsu-Hsin Chuang  Li-Chung Wu  Dong-Jiing Doong  Chia Chuen Kao 《Ocean Engineering》2008,35(10):1039-1051

The wavelet transform (WT) is now recognized as a useful, flexible, and efficient technique to analyze intermittent, non-stationary and inhomogeneous signals as well as images which are obtained from experimental or in situ measurements. In this study, the two-dimensional continuous wavelet transform (2-D CWT) was introduced to analyze the spatial image of waves. The numerical algorithm of 2-D CWT was developed and testified in simulated wave field of regular and random waves. Some more simulated wave fields of various wave conditions and sea bed slopes were then assumed to verify the analytical accuracy of this new technique. The comparisons of estimations to theoretical values for several wave parameters show that the 2-D CWT is capable of identifying the directional spectra and wave properties in shallow water.  相似文献   

Microfabric and rock properties of experimentally compressed silt-clay mixtures     

Manzar Fawad  Nazmul Haque MondolJens Jahren  Knut Bjørlykke 《Marine and Petroleum Geology》2010

Oedometric mechanical compaction tests were performed on brine-saturated synthetic samples consisting of silt-clay mixtures to study changes in microfabric and rock properties as a function of effective stress. The silt consisted of crushed quartz (∼100%) with grain size range between 4 and 40 μm, whereas the clay consisted of 81% kaolinite, 14% mica/illite and 5% microcline of grain size between 0.4 and 30 μm. Five sample pairs ranging in composition from pure silt to pure clay were compacted to 5 and 50 MPa effective stress respectively. SEM studies were carried out to investigate microfabric changes in the mechanically compacted silt-clay mixtures. The degree of alignment of the different minerals present (quartz, mica/illite and kaolinite) were computed by using an image analysis software. Experimental compaction have measured the changes in the rock properties such as porosity and velocity as a function of effective stress for different mixtures of clay and silt. Clay-rich samples showed a higher degree of mineral orientation and lower porosity compared to silt-dominated samples as a function of effective stress. Pure clay sample had 11% porosity at 50 MPa effective stress whereas the pure silt sample retained about 29% porosity at the same effective stress. The experiments showed that low porosity down to 11% is possible by mechanical compaction only. A systematic increase in strain was observed in the silt-clay mixtures with increasing clay content but the porosity values found for the 50:50 silt-clay mixture were lower than that of 25:75 silt-clay mixture. No preferential mineral orientation is expected before compaction owing to the high initial porosity suggesting that the final fabric is a direct result of the effective stress. Both P- and S-wave velocities increased in all silt-clay mixtures with increasing effective stress. The maximum P- and S-wave velocities were observed in the 25:75 silt-clay mixture whereas the minimum Vp and Vs were recorded in the pure silt mixture. At 50 MPa effective stress P- wave velocities as high as 3 km/s resulted from experimental mechanical compaction alone. The results show that fine-grained sediment porosity and velocity are dependent on microfabric, which in turn is a function of grain size distribution, particle shape, sediment composition and stress. At 5 MPa effective stress, quartz orientation increased as a function of the amount of clay indicating that clay facilitate rotation of angular quartz grains. Adding clay from 25% to 75% in the silt-clay mixtures at 50 MPa effective stress decreased the quartz alignment. The clay mineral orientation increased by increasing both the amount of clay and the effective stress, the mica/illite fabric alignment being systematically higher than that of kaolinite. Even small amount of silt (25%) added to pure clay reduced the degree of clay alignment significantly. This study demonstrates that experimental compaction of well characterized synthetic mudstones can be a useful tool to understand microfabric and rock properties of shallow natural mudstones where mechanical compaction is the dominant process.  相似文献