Data analysis on the extrasolar planets using robust clustering

We use both the conventional and more recently developed methods of cluster analysis to study the data of extrasolar planets (exoplanets). Using the data set with planetary mass M , orbital period P and orbital eccentricity e , we investigate the possible clustering in the  ln  M ,  ln  P ,  ln  P –ln  M ,   e   and ln   P – e spaces. There are two main implications: (1) mass distribution is continuous, and (2) orbital population could be classified into three clusters, which correspond to the exoplanets in the regimes of tidal, ongoing tidal and disc interaction, respectively.     

Predicting soil erosion hazard in Lattakia Governorate(W Syria)

The main objective of this study is to predict soil erosion in the Lattakia Governorate(WSyria)using the Water Erosion Prediction Project model(WEPP)and to compare the result with that of the RUSLE.Field survey and data collection were carried out,and 44 soil samples were analyzed.In addition,all the necessary input files were prepared for use in the WEPP model and RUSLE.Results show that more than of 80%of the locations studied experience slight to moderate erosion(less than 5 t/ha/y),whereas the rest of the locations experience severe soil erosion hazard.Moreover,the volume of runoff estimated by the WEPP model is in the range of 51e321 mm,and the R^2 between the simulated soil erosion and the predicted runoff reached 0.68.Interestingly,the R^2 between the WEPP model and RUSLE is 0.56,which indicates a good correlation between the two models.     

Influence of phosphate on the oxidation kinetics of nanomolar Fe(II) in aqueous solution at circumneutral pH

The oxygenation kinetics of nanomolar concentrations of Fe(II) in aqueous solution have been studied in the absence and presence of millimolar concentrations of phosphate over the pH range 6.0-7.8. At each phosphate concentration investigated, the overall oxidation rate constant varied linearly with pH, and increased with increasing phosphate concentration. A model based on equilibrium speciation of Fe(II) was found to satisfactorily explain the results obtained. From this model, the rate constants for oxygenation of the Fe(II)-phosphate species FeH₂PO₄⁺, FeHPO₄ and FePO₄⁻ have been determined for the first time. FePO₄⁻ was found to be the most kinetically reactive species at circumneutral pH with an estimated oxygenation rate constant of (2.2 ± 0.2) × 10 M⁻¹ s⁻¹. FeH₂PO₄⁺ and FeHPO₄ were found to be less reactive with oxygen, with rate constants of (3.2 ± 2) × 10⁻² M⁻¹ s⁻¹ and (1.2 ± 0.8) × 10⁻¹ M⁻¹ s⁻¹, respectively.     

Geochemistry of surface waters in the vicinity of open pit mines at the Cay Cham deposit, Thai Nguyen province, northern Vietnam

This study provides an assessment of the environmental impact of open pit mining operations at the Cay Cham titanomagnetite-ilmenite deposit (northern Vietnam). The results of surface water sampling indicate the formation of acid mine drainage and contamination of adjacent areas by heavy metals (Cu, Zn, Ni, and Mn). The acid mine drainage is produced by oxidation leaching of sulfide minerals associated with primary mineralization owing to the low neutralization potential of the natural waters in the humid environment of tropical rainforest. The study showed that alternating dry and wet seasons typical of this climatic region promote the generation of stored acidity leading to a sharp decrease in pH of drainage water during the wet season and result in the negative impacts of this mine on both flowing and stagnant surface waters.     

Application of a feature-based approach to debris flow detection by numerical simulation

A debris flow is a serious natural disaster which can occur anywhere whether in a valley or on a mountain slope, destroying everything it passes through. Debris flows can occur suddenly and cause residents in the path to suffer casualties and property loss. An early warning system is necessary to reduce the damage in order to protect human life and personal property. However, most debris flow detection systems, like wireless sensors, satellite images and radar, are not suitable for general public use. Vision surveillance systems are generally erected in Taiwan as public devices for security. Therefore, we propose a novel debris early warning system that uses a computer vision technique and build a simulation environment to prove the feasibility.     

Application of multimedia methodology for investigation of karst water in highland regions of Ha Giang Province, Vietnam

Ha Giang is one of the largest, northern border provinces of Vietnam, consisting of four districts: Yen Minh, Quan Ba, Dong Van and Meo Vac. This province features varied karst landscape of Carboniferous–Permian limestone. The region has been recognized by UNESCO as one of the 77 geological parks in the world and the second in Southeast Asia on 3 October 2012. In the dry season, little or no rain is recorded; therefore, surface water is very scarce. For this reason, proper delineation and exploitation of the groundwater resource is critical for sustainable water supply. This has been identified as an important challenge under the scientific project KC-08-10 in the national program KC-08. Remote sensing and GIS were used to decipher the signature of karst water in the highland of Ha Giang. Information layers generated were subjected to multi-criteria evaluation using analytic hierarchy process for decision making to identify ideal locations for groundwater prospecting. The study resulted in delineation of ten zones for all regions and 18 ideal drilling sites in Tam Son Town of Quan Ba District. Drilling and resistivity soundings were performed to assess the success of the interpretation. Deep resistivity survey confirmed low resistivity (200–300 Ωm) near the identified potential sites in Tam Son Town of Quan Ba District. Further, successful drilling at site LKTS1 with a discharge of 7–9 l/s is observed, proving the potential of this methodology for rapid exploration of groundwater in water-scare karst terrains of Vietnam.     

Removal of Two Pharmaceutically Active Compounds from Aqueous Phase Using an Engineered Floodplain Filtration System

This study investigated the removal of two model pharmaceutically active compounds (PhAcs), viz., ibuprofen and triclosan, in lab‐scale engineered floodplain filtration (EFF) system. Biodegradation experiments were performed to acquire knowledge about the degradation of the targeted PhAcs, at an initial concentration of 350 µg/L. Biodegradation results showed that the two compounds were bio‐transformed to >70% after 15 days of incubation. Column tests were performed in a statistically significant manner to determine the adsorptive potential of the suggested filler layer in the EFF (C/C₀), by varying the flow rate and initial concentration of the compound. It was observed based on the F and p‐values that the main effects (F = 3163, p < 0.005) were more significant than the interactive effects (F = 9561, p < 0.05) for both ibuprofen and triclosan removal. Besides, by performing the Student's “t” test, it was concluded that the flow rate plays a major role in determining the rapidness of achieving complete breakthrough than the initial concentration of both the compounds. The data obtained from column studies under biotic conditions indicated that the removal mechanism for PhAcs is mainly biotransformation based, and that an EFF system may be effectively used to remove these emerging compounds during ground water recharge for water recycling.     

The use of isotopes in evolving groundwater circulation models of regional continental aquifers: The case of the Guarani Aquifer System

The Guarani Aquifer System (GAS) has been studied since the 1970s, a time frame that coincides with the advent of isotopic techniques in Brazil. The GAS isotope data from many studies are organized in different phases: (a) the advent of isotope techniques, (b) consolidation and new applications, (c) isotope assessments and hydrochemistry evolution, and (d) a roadmap to a new conceptual model. The reasons behind the phases, their methodological approaches, and impacts on the regional flow conceptual models are examined. Starting with local δ²H and δ¹⁸O assessments of values for water fingerprinting and estimates of recharge palaeoclimate scenarios, studies evolved to more integrated approaches based on multiple tracers. Stable isotope application techniques were consolidated during the 1980s, when new dating approaches dealing with radiogenic and heavy isotopes were introduced. Through the execution of an international transboundary project, the GAS was studied and extensively sampled for isotopes. These results have triggered wider application of isotope techniques, reflecting also world research trends. Presently, hydrochemical evolution models along flow lines from recharge to discharge areas, across large‐scale tectonic features within the entire sedimentary basin, are being combined with residence time estimates at GAS outcrop areas and deep confined units. In a complex system, it is normal that many, and even contradictory hypotheses are proposed, but isotope techniques provide a unique chance to test them. Stable isotope assessments are still needed near recharge areas, and they can be combined with groundwater classical dating procedures, complemented by newer techniques (³H‐³He, CFCs, and SF₆)_. Recent noble gas sampling and world pioneer analytical efforts focused on the confined units in the GAS will certainly led to new findings on the overall GAS circulation. The objective of this article is to discuss how isotope information can contribute to the evolution of conceptual groundwater flow models for regional continental aquifers, such as the GAS.     

Evolution of pore structure and hydraulic conductivity of randomly distributed soluble particle mixture

The plane strain behavior of particulate mixtures containing soluble particles was investigated by conducting both laboratory tests and numerical analysis. To perform the laboratory experiments, soluble mixtures were prepared using photoelastic disks and ice disks with diameters in the ratios (D_{ice disk}/D_{photoelastic disk}) of 0.5 and 0.7, and the evolution of the force chain and pore structure was monitored during the dissolution of the ice disks. Subsequently, numerical analysis was conducted by using the 2‐dimensional discrete element method for the soluble mixtures, and it was compared with the experimental results. Additionally, parametric studies were implemented by varying the particle size ratios between the soluble and non‐soluble particles and the volumetric fraction of the soluble particles. The results of the laboratory experiments and numerical analysis demonstrate that (1) after the dissolution of the soluble particles, the pore fabric of the specimens changed, resulting in a force chain changes, local void increases, and coordination number decreases; (2) the effects of soluble particles on the macro‐behaviors of the mixtures could be divided into 3 zones based on the particle size ratios between the soluble and non‐soluble particles and volumetric fraction of soluble particles. These zones were as follows: (Zone 1)—with a small total soluble volume, slight decrease in the in situ lateral pressure (K₀), and minor increase in the hydraulic conductivity (k); (Zone 2)—with a moderate soluble particle; the dissolution generated a honey‐comb particle structure; (Zone 3)—the total soluble volume was very large, and the high volumetric fraction of the dissolving particle collapsed the pore structure, decreasing in the in situ lateral pressure (K₀) but increasing the hydraulic conductivity (k). The horizontal stress returned to almost the original level, and the internal arching formation increased significantly with the hydraulic conductivity (k).