广西百色盆地重磁力结合遥感资料在盆地早期评价中的综合研究

本文以百色盆地为例,着重阐述了重磁资料在盆地早期评价中所起的重要作用,提出并总结了重磁资料在盆地早期评价系统中与遥感等资料综合研究的方法系列,指出重磁处理系统是盆地早期评价系统中不可分割的重要部分,遥感图像处理、石油重磁处理系统和地理信息系统(GIS)是进行多元信息综合的强有力的工具。     

人工聚沙堤防治铁路沙害的初期试验研究

本文介绍了在高寒干旱的青藏铁路线伏沙梁地段,采用人工聚沙堤阻截外来风沙流的试验。通过初期试验观测,对人工聚沙堤的聚沙形式结构和防沙效果进行了阐述,提出人工聚沙堤是整治该段铁路沙害的一种主要措施。     

Organic Matter Accumulation in the Upper Permian Dalong Formation from the Lower Yangtze Region, South China

The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions, acting as important unconventional hydrocarbon source rocks. However, the mechanism of organic matter (OM) enrichment throughout this period is still controversial. Based on geochemical data, the marine redox conditions, paleogeographic and hydrographic environment, primary productivity, volcanism, and terrigenous input during the Late Permian in the Lower Yangtze region have been studied from the Putaoling section, Chaohu, to provide new insights into OM accumulation. Five Phases are distinguished based on the TOC and environmental variations. In Phase I, anoxic conditions driven by water restriction enhanced OM preservation. In Phase II, euxinic and cycling hydrological environments were the two most substantial controlling factors for the massive OM deposition. During Phase III, intensified terrestrial input potentially diluted the OM in sediment and the presence of oxygen in bottom water weakened the preservation condition. Phase IV was characterized by a relatively higher abundance of mercury (Hg) and TOC (peak at 16.98 wt%), indicating that enhanced volcanism potentially stimulated higher productivity and a euxinic environment. In Phase V, extremely lean OM was preserved as a result of terrestrial dilutions and decreasing primary productivity. Phases I, II and IV are characterized as the most prominent OM-rich zones due to the effective interactions of the controlling factors, namely paleogeographic, hydrographic environment, volcanism, and redox conditions.     

Field strength prediction of mobile communication network based on GIS

This article describes GIS-based models successfully developed for predicting the coverage of Cityphone cellular network, visualizing the predicted signal strength, and analyzing the field strength coverage. In order to predict the signal coverage strength of communication network more accurately, the spatial and nonspatial databases of a mobile cellular network are combined by GIS and produce the necessary parameters. A GIS model named COST-231-Walfisch–Ikegami model (WIM) is developed for signal coverage prediction in Ho Chi Minh City. Radio-line-of-sight and nonradio-line-of-sight conditions can be determined by this model. In addition, in case of nonradio-line-of-sight conditions, average building height, building separation, building width, incident radio path, and road orientation with respect to the direct radio path were obtained using GIS. Road orientation loss, multiscreen diffraction loss, and shadowing gain were predicted more accurate by this model. The scale of maps in the experiment was 1:2000 and the average of floor height was 3?m because there were no exact building height measurements. Statistical results show that the path loss predicted by the COST 231 WIM overcame the real path loss of each cell station. And this method can be used for signal coverage prediction of mobile cellular network in urban areas. Compared to the current situation with the Ho Chi Minh City Posts and Telecommunications system, this model can be effectively applied to improve the Cityphone mobile network quality as well as capability. Developed GIS models can help designers in predicting cell station coverage using real spatial maps that make the results more reliable. This research can help network operators improve the network quality and capability with the best investment efficiently.     

Influence of solar activity on the state of the wheat market in medieval England

The database of professor Rogers (1887), which includes wheat prices in England in the Middle Ages, was used to search for a possible influence of solar activity on the wheat market. Our approach was based on the following: (1) Existence of the correlation between cosmic ray flux entering the terrestrial atmosphere and cloudiness of the atmosphere. (2) Cosmic ray intensity in the solar system changes with solar activity, (3) Wheat production depends on weather conditions as a nonlinear function with threshold transitions. (4) A wheat market with a limited supply (as it was in medieval England) has a highly nonlinear sensitivity to variations in wheat production with boundary states, where small changes in wheat supply could lead to bursts of prices or to prices falling. We present a conceptual model of possible modes for sensitivity of wheat prices to weather conditions, caused by solar cycle variations, and compare expected price fluctuations with price variations recorded in medieval England. We compared statistical properties of the intervals between wheat price bursts during the years 1249-1703 with statistical properties of the intervals between the minima of solar cycles during the years 1700-2000. We show that statistical properties of these two samples are similar, both for characteristics of the distributions and for histograms of the distributions. We analyze a direct link between wheat prices and solar activity in the 17^th century, for which wheat prices and solar activity data (derived from ¹⁰Be isotope) are available. We show that for all 10 time moments of the solar activity minima the observed prices were higher than prices for the corresponding time moments of maximal solar activity (100% sign correlation, on a significance level < 0.2%). We consider these results a direct evidence of the causal connection between wheat prices bursts and solar activity.     

Integrated Reservoir Characterization and Petrophysical Analysis of Cretaceous Sands in Lower Indus Basin,Pakistan

The reservoir character of the Cretaceous sand is evaluated in Lower Indus Basin, Pakistan where water flooding is very common. Thus, prediction of subsurface structure, lithology and reservoir characterization is fundamental for a successful oil or gas discovery. Seismic reflective response is an important tool to detect sub-surface structure. Seismic reflection response is not enough to highlight geological boundaries and fluids in the pore space therefore, the use of integrated approach is vital to map sub-surface heterogeneities with high level of confidence. Based on seismic character and continuity of prominent reflectors four seismic horizons are marked on the seismic sections. All the strata is highly disturbed and distorted with presence of a network of fault bounded horst and graben structures, which indicate that the area was under compressional tectonic regime. These fault bounded geological structure formed structural traps favorable for the accumulation of hydrocarbon. The petrophysical analysis reveals that the Cretaceous sand formation has four types of sand: Sand A, B, C and D with good porosity (15 % average) and low volume of shale. Although complete petroleum system is present with structural traps and reservoir character of sand interval is very good but these sands are highly saturated with water thus are water flooded, which is the main reason of the abundant wells in the study area.     

Soil erosion assessment on hillslope of GCE using RUSLE model

A new method for obtaining the C factor (i.e., vegetation cover and management factor) of the RUSLE model is proposed. The method focuses on the derivation of the C factor based on the vegetation density to obtain a more reliable erosion prediction. Soil erosion that occurs on the hillslope along the highway is one of the major problems in Malaysia, which is exposed to a relatively high amount of annual rainfall due to the two different monsoon seasons. As vegetation cover is one of the important factors in the RUSLE model, a new method that accounts for a vegetation density is proposed in this study. A hillslope near the Guthrie Corridor Expressway (GCE), Malaysia, is chosen as an experimental site whereby eight square plots with the size of \(8\times 8\) and \(5\times 5\) m are set up. A vegetation density available on these plots is measured by analyzing the taken image followed by linking the C factor with the measured vegetation density using several established formulas. Finally, erosion prediction is computed based on the RUSLE model in the Geographical Information System (GIS) platform. The C factor obtained by the proposed method is compared with that of the soil erosion guideline Malaysia, thereby predicted erosion is determined by both the C values. Result shows that the C value from the proposed method varies from 0.0162 to 0.125, which is lower compared to the C value from the soil erosion guideline, i.e., 0.8. Meanwhile predicted erosion computed from the proposed C value is between 0.410 and \(3.925\, \hbox {t ha}^{-1 }\,\hbox {yr}^{-1}\) compared to 9.367 to \(34.496\, \hbox {t ha}^{-1}\,\hbox {yr}^{-1 }\) range based on the C value of 0.8. It can be concluded that the proposed method of obtaining a reasonable C value is acceptable as the computed predicted erosion is found to be classified as a very low zone, i.e. less than \(10\, \hbox {t ha}^{-1 }\,\hbox {yr}^{-1}\) whereas the predicted erosion based on the guideline has classified the study area as a low zone of erosion, i.e., between 10 and \(50\, \hbox {t ha}^{-1 }\,\hbox {yr}^{-1}\).     

鱼礁模型对赤点石斑鱼的诱集效果

本文在实验室中水池中观察了赤点石斑鱼在三种不同口径鱼礁模型存在下的行为，结果表明；鱼礁对这种鱼有明显诱集效果，随着模型口径的增大，鱼在礁体放置区分布百分率有增大趋势，而鱼个体平均距离、群体总重心与礁体平均距离和鱼与礁的距离均有减小趋势。可见，口径大小的鱼礁模型有较好的聚鱼效果。