An efficient method of generating random permeability fields by the source point method

Aquifer properties, for example permeability and porosity, vary in space and may be characterized by their distributions. The property distribution is not totally random but shows some correlation structure. Because most of the values are not known, some rational method is required to generate credible aquifer distribution properties for inclusion in fluid transport models. This paper presents a numerically efficient method of generating geostatistical random fields, by the source Point Method (SPM). The SPM is a very efficient method and requires little computer time and relatively small data storage, as compared to other methods of generating random fields. In addition, the SPM is modified to include any desired amount of anisotropy in the property distribution of a system. By using conditional covariances, a formula for a two-dimensional anisotropic field is derived to prespecify the desired correlation length in any direction. Results show that for an anisotropic medium the correlation length can be pre-specified in any specific direction.     

解决语义悖论的振荡周期函数模型--一种对语义悖论的可能解释

通过对悖论性命题的仔细分析，发现这些命题的真值会发生周期性的变化。因此，将振荡周期函数纳入语形学，以便从形式上揭示悖论性命题真假周期性过渡这种对立统一结构，再纳入动态蒙太格赋予振荡函数里的变元以意义，这样就从语形、语义、语用的角度构建了一种动态语义模型，从而达到消解语义悖论的目的。     

Transit station or destination? Attendance patterns,movements and abundance estimate of humpback whales off west South Africa from photographic and genotypic matching

Humpback whales Megaptera novaeangliae found off west South Africa (WSA) are known to display an atypical migration that may include temporary residency and feeding during spring and summer. At a regional scale there is uncertainty about how these whales relate to the greater West African Breeding Stock B as a whole, with evidence both for and against its division into two substocks. A database containing sighting information of humpback whales intercepted by boat in the WSA region from 1983 to 2008 was compiled. It included a total of 1 820 identification images of ventral tail flukes and lateral views of dorsal fins. After systematic within- and between-year matching of images of usable quality, it yielded 154 different individuals identified by tail flukes (TF), 230 by left dorsal fins (LDF), and 237 by right dorsal fins (RDF). Microsatellite (MS) matching of 216 skin biopsies yielded 156 individuals. By linking all possible sightings of the same individuals using all available identification features, the periodicity and seasonality of 281 individual whales were examined. In all, 60 whales were resighted on different days of which 44 were between different calendar years. The most resightings for one individual was 11 times, seen in six different years, and the longest interval between first and last sightings was about 18 years. A resighting rate of 15.6% of whales at intervals of a year or more indicates long-term fidelity to the region. Shorter intervals of 1–6 months between sequential sightings in the same year may suggest temporary residency. The TF image collection from WSA was compared to TF collections from four other regions, namely Gabon, Cabinda (Angola), Namibia and the Antarctic Humpback Whale Catalogue (AHWC). Three matches were detected between WSA (in late spring or summer) and Gabon (in winter), confirming direct movement between these regions. The capture–recapture data of four different identification features (TF, RDF, LDF and MS) from six successive subsets of data from periods with the highest collection effort (2001–2007) were used to calculate the number of whales that utilise the region, using both closed- and open-population models. Dorsal fins have never been used to estimate abundance for humpback whales, so the different identification features were evaluated for potential biases. This revealed 9–14% incidence of missed matches (false negatives) when using dorsal fins that would result in an overestimate, whereas variation in individual fluke-up behaviour may lower estimates by as much as 57–66% due to heterogeneity of individual capture probability. Taking into consideration the small dataset and low number of recaptures, the most consistent and precise results were obtained from a fully time-dependent version of the Jolly-Seber open-population model, with annual survival fixed at 0.96, using the MS dataset. This suggests that the WSA feeding assemblage during the months of spring and summer (September–March) of the study period numbered about 500 animals. The relationship of these whales to those (perhaps strictly migratory) that may occur in other seasons of the year, and their links to possible migratory routes and other feeding or breeding areas, remain uncertain.     

A practical method for identifying parameters in the seismic design of embankments

The effect of heterogeneity of soils on a seismic design procedure based on residual displacement according to safety factors is examined. Although soils are heterogeneous in nature, at present the seismic designs of embankments implement the assumption that soils are homogeneous. In this study, a seismic reliability analysis using a Monte Carlo simulation and considering the heterogeneity of soil strength was applied to the Newmark sliding block method. The data of the analysis in this study were based on in-situ soil test results of actual airport embankments. This paper indicates a rational and practical approach to modifying the actual heterogeneous soil conditions into homogeneous design parameters for the Newmark sliding block method in homogeneous ground conditions.     

储层构型研究进展与展望

本文从储层构型概念出发,概括了国内学者对河流相、冲积扇、三角洲等不同沉积领域的储层构型研究方法和取得的成果,并在此基础上了归纳总结了现阶段储层构型研究所遇到问题,最后针对目前的研究现状和存在的问题,指出了储层构型研究的发展趋势,这将对研究储层非均质性、剩余油分布及提高油气采收率等具有十分重要意义。