越南红河平原区新生代构造应力场特征

红河平原在新生代期间受印度板块、欧亚板块和太平洋板块三大板块的影响,其构造应力场复杂多样.通过研究红河平原新生代构造应力场的变化规律,确定在新生代早期红河平原地区的构造应力场特点为东西的挤压应力场与左旋走滑机制,晚期则转变为南北的挤压应力场与右旋走滑机制,且右旋走滑作用在东南部地区呈增加趋势.红河平原区的这种构造应力场的变化为对红河三角洲的形成和发展提供了条件,控制了红河平原地区的现代构造活动特征.     

Late Pleistocene–Holocene history of the Golden Horn Estuary,Istanbul

The historical Golden Horn Estuary (GHE), near the confluence of the Istanbul Strait (Bosphorus) and the Sea of Marmara in the European part of Istanbul, has been used as a natural harbor since 330 a.d. The sedimentary infill of the GHE is 15–46 m thick, deposited unconformably above the turbiditic sandstones of the Carboniferous Trakya Formation. Chronostratigraphic and paleontological analyses of the infill sequence indicate that the GHE was a fluvial channel prior to 13,500 cal. a (calibrated to calendar years) B.P. It subsequently became gradually influenced by marine waters, and was a brackish-water environment until 9,500 cal. a B.P. Normal marine salinities prevailed at ca. 9,500−5,600 cal. a B.P., with suboxic/dysoxic bottom-water conditions. The increase in salinity at 9,500 cal. a B.P. was most likely caused by Mediterranean water outflow into the Black Sea through the Istanbul Strait. The estuary was influenced by large fluvial inputs between 5,600 and 1,000 cal. a B.P., possibly during a distinct pluvial period, as shown by coarse siliciclastic sediments deposited on the flanks. It has become a highly polluted environment with marked anthropogenic inputs during the last millennium. The finding that the sediment infill sequence above the Carboniferous basement is not older than about 20 ka strongly suggests that the Golden Horn Estuary acquired its present-day morphology during the late glacial–Holocene period.     

重力方法研究越南早新生代基底效果分析(英文)

为了提高用重力方法在越南研究早新生代基底结构特点中的效率,表明作者们提出了一个综合分析地质及地球物理资料的系统方法.获得的研究结果表明:1)一个大的平均密度差是在用重力方法研究越南的早新生代基底时效率的一个基本因素;2)用多维线性相关分析来有效研究和预测越南的早新生代基底岩石的埋藏深度与密度是有可能的;3)通过利用多维线性分析预测密度以及泊松系数使我们能预测早新生代基底岩石.     

Prediction of Blast-induced Air Over-pressure in Open-Pit Mine: Assessment of Different Artificial Intelligence Techniques

Air over-pressure (AOp) is one of the products of blasting operations for rock fragmentation in open-pit mines. It can cause structural vibration, smash glass doors, adversely affect the surrounding environment, and even be fatal to humans. To assess its dangerous effects, seven artificial intelligence (AI) methods for predicting specific blast-induced AOp have been applied and compared in this study. The seven methods include random forest, support vector regression, Gaussian process, Bayesian additive regression trees, boosted regression trees, k-nearest neighbors, and artificial neural network (ANN). An empirical technique was also used to compare with AI models. The degree of complexity and the performance of the models were compared with each other to find the optimal model for predicting blast-induced AOp. The Deo Nai open-pit coal mine (Vietnam) was selected as a case study where 113 blasting events have been recorded. Indicators used for evaluating model performances include the root-mean-square error (RMSE), determination coefficient (R²), and mean absolute error (MAE). The results indicate that AI techniques provide better performance than the empirical method. Although the relevance of the empirical approach was acceptable (R²?=?0.930) in this study, its error (RMSE?=?7.514) is highly significant to guarantee the safety of the surrounding environment. In contrast, the AI models offer much higher accuracies. Of the seven AI models, ANN was the most dominant model based on RMSE, R², and MAE. This study demonstrated that AI techniques are excellent for predicting blast-induced AOp in open-pit mines. These techniques are useful for blasters and managers in controlling undesirable effects of blasting operations on the surrounding environment.

     

Novel Soft Computing Model for Predicting Blast-Induced Ground Vibration in Open-Pit Mines Based on Particle Swarm Optimization and XGBoost

Natural Resources Research - Blasting is a useful technique for rocks fragmentation in open-pit mines, underground mines, as well as for civil engineering work. However, the negative impacts of...     

Prediction of Blast-Induced Ground Vibration in Open-Pit Mines Using a New Technique Based on Imperialist Competitive Algorithm and M5Rules

Natural Resources Research - In this paper, blast-induced ground vibration (BIGV) was considered as the primary objective, and a new artificial intelligence system was proposed to predict BIGV with...     

Mean and variance evolutions of the hot and cold temperatures in Europe

In this paper, we examine the trends of temperature series in Europe, for the mean as well as for the variance in hot and cold seasons. To do so, we use as long and homogenous series as possible, provided by the European Climate Assessment and Dataset project for different locations in Europe, as well as the European ENSEMBLES project gridded dataset and the ERA40 reanalysis. We provide a definition of trends that we keep as intrinsic as possible and apply non-parametric statistical methods to analyse them. Obtained results show a clear link between trends in mean and variance of the whole series of hot or cold temperatures: in general, variance increases when the absolute value of temperature increases, i.e. with increasing summer temperature and decreasing winter temperature. This link is reinforced in locations where winter and summer climate has more variability. In very cold or very warm climates, the variability is lower and the link between the trends is weaker. We performed the same analysis on outputs of six climate models proposed by European teams for the 1961–2000 period (1950–2000 for one model), available through the PCMDI portal for the IPCC fourth assessment climate model simulations. The models generally perform poorly and have difficulties in capturing the relation between the two trends, especially in summer.     

Predictability of the wintertime 500 hPa geopotential height over Ural-Siberia in the NCEP climate forecast system

Climate Dynamics - Using hindcast and forecast data from the National Centers for Environmental Prediction (NCEP) climate forecast system version 2 (CFSv2) for the period 1982–2017, we...     

Improving watershed management practices in humid regions

In many parts of the world, watershed management practices have been extremely effective. However, implementation of soil and water conservation technologies in the humid African highlands, while beneficial in the short term, were remarkably unsuccessful in the long term. Insights from community knowledge perspectives have revealed that alternative methods are needed. Although conservation practices are designed to conserve water in semi‐arid areas, safely draining excess water is needed in humid areas. The objective of this paper is to review current watershed management approaches used in humid regions as exemplified by those used in Ethiopian highlands and then based on these findings propose more effective practices. Although current government sponsored practices primarily protect the hillsides, direct run‐off is generated from areas that become saturated on valley bottoms near rivers and on specific parts of the hillsides with degraded soils (or with highly permeable surface soils) and with perched water tables on slowly permeable horizons at shallow depths. In these areas, direct run‐off is increasing with deforestation and the soil degradation, demanding additional drainage ways that evolve in the form of gullies. Therefore, watershed management interventions for erosion control should prioritize revegetation of degraded areas, increasing sustainable infiltration, and rehabilitating gullies situated at saturated bottomlands.