One-phase-low-pH enzyme induced carbonate precipitation (EICP) method for soil improvement     

Cui  Ming-Juan  Lai  Han-Jiang  Hoang  Tung  Chu  Jian 《Acta Geotechnica》2021,16(2):481-489

Enzyme induced carbonate precipitation (EICP) is an emerging soil improvement method using free urease enzyme for urea hydrolysis. This method has advantages over the commonly used microbially induced carbonate precipitation (MICP) process as it does not involve issues related to bio-safety. However, in terms of efficiency of calcium carbonate production, EICP is considered lower than that of MICP. In this paper, a high efficiency EICP method is proposed. The key of this new method is to adopt a one-phase injection of low pH solution strategy. In this so-called one-phase-low-pH method, EICP solution consisting of a mixture of urease solution of pH?=?6.5, urea and calcium chloride is injected into soil. The test results have shown that the one-phase-low-pH method can improve significantly the calcium conversion efficiency and the uniformity of calcium carbonate distribution in the sand samples as compared with the conventional two-phase EICP method. Furthermore, the unconfined compressive strength of sand treated using the one-phase-low-pH method is much higher than that using the two-phase method and the one-phase-low-pH method is also simpler and more efficient as it involves less number of injections.

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Using Geomorphological Indicators to Predict Earthquake Magnitude (MOb‒Max): A Case Study from Cao Bang Province and Adjasent Areas (Vietnam)     

Trong  C. D.  Hoang  N.  Bach  M. X.  Luc  N. M.  Dung  L. V.  Trieu  C. D.  Syrbu  N. S.  Hai  D. Th.  Tuan  Th. A.  Toan  N. Q.  Thanh  D. V. 《Geotectonics》2022,56(3):321-338

Geotectonics - This paper presents analysis of geomorphological indices for predicting the maximum observed earthquake (MOb?Max) in research region, conducted in three steps: (i)...  相似文献   

Description of a complex,rainfall-induced landslide within a multi-stage three-dimensional model     

Tran  T. V.  Alvioli  M.  Hoang  V. H. 《Natural Hazards》2022,110(3):1953-1968

Natural Hazards - The mechanical processes involved in movements of earth or rock masses under the effect of gravity—a landslide—may include several phases where the failure of one...  相似文献   

Methodology for evaluation of potential sites for large-scale riverbank filtration     

Hoang  Ngoc Anh T.  Covatti  Gustavo  Grischek  Thomas 《Hydrogeology Journal》2022,30(6):1701-1716

Despite being a simple and inexpensive pretreatment technology, the cost-effectiveness of riverbank filtration (RBF) depends on complex hydrogeological and hydrogeochemical variables. One of the most important issues for decision makers regarding RBF is optimal site selection. Therefore, a methodology for multicriteria site evaluation for large-scale RBF schemes is offered. The methodology is primarily designed as a prescreening method, applied over a wide area, but can also serve as a guide for evaluating individual RBF sites. To facilitate further discussion about improvements on the methodology, the reasoning behind each relevant factor and its weight in the evaluation is presented. The methodology is divided into three sequential steps through which a site can be assessed. The first step is to establish the existence of connectivity between the river and aquifer. This is termed the essential criterion, and is a binary determination of site suitability. If the site is determined to be suitable, it is then assessed via a set of quantity criteria, which measure the aquifer capacity and amount of bank filtrate that can be effectively abstracted. Lastly, water quality criteria are assessed by means of surface-water and groundwater quality. The quantity and quality criteria form a result expressed as the site suitability index (SSI), which ranges from 0 to 1, where higher scores represent increased suitability. Finally, the methodology is applied to evaluate existing sites of large-scale RBF application as a demonstration of its applicability. The success of these existing sites is compared to the calculated SSI value and discussed.

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Controls on erosion patterns and sediment transport in a monsoonal,tectonically quiescent drainage,Song Gianh,central Vietnam          下载免费PDF全文

Tara N. Jonell  Peter D. Clift  Long V. Hoang  Tina Hoang  Andrew Carter  Hella Wittmann  Philipp Böning  Katharina Pahnke  Tammy Rittenour 《Basin Research》2017,29(Z1):659-683

The Song Gianh is a small‐sized (~3500 km²), monsoon‐dominated river in northern central Vietnam that can be used to understand how topography and climate control continental erosion. We present major element concentrations, together with Sr and Nd isotopic compositions, of siliciclastic bulk sediments to define sediment provenance and chemical weathering intensity. These data indicate preferential sediment generation in the steep, wetter upper reaches of the Song Gianh. In contrast, detrital zircon U‐Pb ages argue for significant flux from the drier, northern Rao Tro tributary. We propose that this mismatch represents disequilibrium in basin erosion patterns driven by changing monsoon strength and the onset of agriculture across the region. Detrital apatite fission track and ¹⁰Be data from modern sediment support slowing of regional bedrock exhumation rates through the Cenozoic. If the Song Gianh is representative of coastal Vietnam then the coastal mountains may have produced around 132 000–158 000 km³ of the sediment now preserved in the Song Hong‐Yinggehai Basin (17–21% of the total), the primary depocenter of the Red River. This flux does not negate the need for drainage capture in the Red River to explain the large Cenozoic sediment volumes in that basin but does partly account for the discrepancy between preserved and eroded sediment volumes. OSL ages from terraces cluster in the Early Holocene (7.4–8.5 ka), Pre‐Industrial (550–320 year BP) and in the recent past (ca. 150 year BP). The older terraces reflect high sediment production driven by a strong monsoon, whereas the younger are the product of anthropogenic impact on the landscape caused by farming. Modern river sediment is consistently more weathered than terrace sediment consistent with reworking of old weathered soils by agricultural disruption.  相似文献   

A Novel Hunger Games Search Optimization-Based Artificial Neural Network for Predicting Ground Vibration Intensity Induced by Mine Blasting     

Nguyen  Hoang  Bui  Xuan-Nam 《Natural Resources Research》2021,30(5):3865-3880

Innovation efforts in developing soft computing models (SCMs) of researchers and scholars are significant in recent years, especially for problems in the mining industry. So far, many SCMs have been proposed and applied to practical engineering to predict ground vibration intensity (BIGV) induced by mine blasting with high accuracy and reliability. These models significantly contributed to mitigate the adverse effects of blasting operations in mines. Despite the fact that many SCMs have been introduced with promising results, but ambitious goals of researchers are still novel SCMs with the accuracy improved. They aim to prevent the damages caused by blasting operations to the surrounding environment. This study, therefore, proposed a novel SCM based on a robust meta-heuristic algorithm, namely Hunger Games Search (HGS) and artificial neural network (ANN), abbreviated as HGS–ANN model, for predicting BIGV. Three benchmark models based on three other meta-heuristic algorithms (i.e., particle swarm optimization (PSO), firefly algorithm (FFA), and grasshopper optimization algorithm (GOA)) and ANN, named as PSO–ANN, FFA–ANN, and GOA–ANN, were also examined to have a comprehensive evaluation of the HGS–ANN model. A set of data with 252 blasting operations was collected to evaluate the effects of BIGV through the mentioned models. The data were then preprocessed and normalized before splitting into individual parts for training and validating the models. In the training phase, the HGS algorithm with the optimal parameters was fine-tuned to train the ANN model to optimize the ANN model's weights. Based on the statistical criteria, the HGS–ANN model showed its best performance with an MAE of 1.153, RMSE of 1.761, R² of 0.922, and MAPE of 0.156, followed by the GOA–ANN, FFA–ANN and PSO–ANN models with the lower performances (i.e., MAE?=?1.186, 1.528, 1.505; RMSE?=?1.772, 2.085, 2.153; R²?=?0.921, 0.899, 0.893; MAPE?=?0.231, 0.215, 0.225, respectively). Based on the outstanding performance, the HGS–ANN model should be applied broadly and across a swath of open-pit mines to predict BIGV, aiming to optimize blast patterns and reduce the environmental effects.

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Estimation of Ground Vibration Intensity Induced by Mine Blasting using a State-of-the-Art Hybrid Autoencoder Neural Network and Support Vector Regression Model     

Ke  Bo  Nguyen  Hoang  Bui  Xuan-Nam  Costache  Romulus 《Natural Resources Research》2021,30(5):3853-3864

Natural Resources Research - In surface mining, blasting is an indispensable method for fragmenting rock masses. Nevertheless, it can inherently induce many side effects like ground vibrations. At...  相似文献   

Predicting Blast-induced Ground Vibration in Quarries Using Adaptive Fuzzy Inference Neural Network and Moth–Flame Optimization     

Bui  Xuan-Nam  Nguyen  Hoang  Tran  Quang-Hieu  Nguyen  Dinh-An  Bui  Hoang-Bac 《Natural Resources Research》2021,30(6):4719-4734

Natural Resources Research - Blasting is a first preparatory stage that plays a fundamental role in the subsequent operations of an open pit mine. However, its adverse effects can seriously affect...  相似文献   

Vertical fault systems in the tectonosphere geoelectrical section in petroliferous domains of Sakhalin Island (Russia) and Gulf of Tonkin (Vietnam): Evidence from magnetotelluric sounding     

V. M. Nikiforov  G. N. Shkabarnya  A. Yu. Zhukovin  V. B. Kaplun  N. A. Palshin  I. M. Varentsov  Do Huy Cuong  Phung Van Phach  Hoang Van Vuong  S. S. Starzhinsky 《Russian Journal of Pacific Geology》2016,10(6):395-407

The transverse current anomalies evident from magnetotelluric sounding (MTS) data in the transition zone from the Asian continent to the Pacific Ocean and a geoelectrical model suitable for explaining these effects are discussed. Using simulation results and new MTS data on Sakhalin and northern Vietnam, ultra-deep fluid–fault system (UDFFS) models are constructed, comprising steeply dipping low-resistivity and high-resistivity linear bodies which penetrate through the whole section of the lithosphere, continuing deep into the asthenosphere. The structure of these systems reflects the development of deep and ultra-deep fault zones, along which mantle-originated fluids may migrate through sediments to reach the surface. This allows the anisotropic–conductive fractured structures adjacent to these faults to be considered as being most favorable for hydrocarbon accumulations.  相似文献   

Simultaneous Organic Matter and Nitrogen Removal from Piggery Slaughterhouse Wastewater Using Bioaugmented Gaslift Membrane Bioreactor     

Nguyen Duc Toan  Nguyen Van Tuyen  Pham Bang Hai  Nguyen Thi Hoang Ha  Do Tien Anh  Bach Quang Dung 《洁净——土壤、空气、水》2023,51(1):2200106

A single bioaugmentation reactor and a side-stream gaslift membrane bioreactor combined with bioaugmentation are conducted to treat real wastewater from a centralized piggery slaughterhouse in Vietnam. The bioaugmented reactor is inoculated with heterotrophic microorganisms (Bacillus sp.) isolated from piggery slaughterhouse wastewater. The results of a single bioaugmentation experiment show high removal efficiency of chemical oxygen demand (COD) (84.8%–97.5%) and total nitrogen (TN) (69.9%–87.2%) at loading rates of 1.28–3.89 and 0.14–0.37 kg m⁻³ d⁻¹, respectively. The combined system demonstrates a significantly higher TN removal efficiency (89.0%–96.1%) (p < 0.001), more stable flux (36.0–38.4 L m⁻² h⁻¹), and transmembrane pressure (0.95–1.05 bar), and better capacity of separation of solid–liquid phases compared to the single bioaugmentation. High COD and TN removal efficiency is possibly due to assimilation and simultaneous nitrification and denitrification processes. The results of this study also indicate the feasibility and propitious efficiency of the bioaugmented gaslift membrane bioreactor for piggery slaughterhouse wastewater treatment.  相似文献