Search Results (8)

The path planning process for an unmanned aerial vehicle is a complex process due to different operating environment conditions and aircraft constraints. The particle swarm optimization algorithm is one of several heuristic techniques used to solve the path planning problem. However, it has been observed that this algorithm tends to converge prematurely to a local optimum, resulting in poor quality paths. This paper proposes an adaptive strategy for calculating the inertia weight (KPSO) of the particles in the PSO algorithm for UAV path planning in a real-world environment. The strategy was applied to a reconnaissance mission during an eruptive event based on the Popocatepetl volcano area in Mexico and was found to outperform other adaptive strategies from the literature in a specific scenario. Full article

Lipases and carboxylesterases are enzymes of biotechnological interest both for their reactions and their specificity. They have wide-ranging applications in the food, pharmaceuticals, biodiesel synthesis, and bioremediation industries. For that reason, the strain Neobacillus thermocopriae C255 was isolated from ash from Popocatepetl volcano and studied as a new source of lipolytic enzymes. It was identified using 16S ribosomal RNA and flagellar protein FliF sequence homology, yielding 100% identity. From the sequencing of its genome, an enzyme with lipolytic activity, classified as a monoacylglycerol lipase, and named Mgl-C255, was cloned in E. coli BL21, and then expressed, biochemically characterized, and tested via transesterification reactions with alcohols and monosaccharides. Based on its sequence and structure, it was placed within family V, having a catalytic triad of S90-D207-H237. Biochemical characterization showed its highest activity at 40 °C, pH 7.5 to 8.5, with C-2 length substrate preference. No metal ions or inhibitors influenced lipolytic activity, except for PMSF, SDS, Cu⁻², and Hg⁻². Mgl-C255 retained about 50% of its activity in non-polar solvents and showed synthetic activity in organic solvents, making it a good candidate for studying its catalytic potential and selectivity. Full article

The noise-like behavior of geomagnetic anomalies observed in Tlamacas station (the Popocatepetl volcano, Mexico), linked to the ionization produced by intensive radon release, is presented in the experimental part of the study. The magnetic-field perturbations produced by electrical currents due to micro-discharges on the terrain irregularities are considered in a theoretical model. The simulations demonstrated that the discharge mechanism can generate perturbations with magnitudes of up to 1–10 nT in the ultra-low frequency (ULF)) range of 10⁻³–10⁻¹ Hz. ULF Magnetic-field perturbations can be higher within storm-weather conditions under an accumulation of electric charges in clouds in the mountainous regions. Full article

The inhalation of natural nanoparticles (NPs) emitted from volcanic activity may be a risk to human health. However, the literature rarely reports the fate and response of NPs once in contact with lung fluids. In this work, we studied the particle size distribution of ashfall from Popocatépetl volcano, Mexico. The collected ashes (n = 5) were analyzed with scanning electron microscopy (SEM) to obtain the elemental composition and morphology, and to determine the size of the ash particles using ParticleMetric software (PMS). The PMS reported most of the ash to have submicrometric size (<1 μm) and an average equivalent circle of 2.72 μm. Moreover, to our knowledge, this study investigated for the first time the behavior of ash NPs at different times (0 to 24 h) while in contact with in vitro lung fluid, Gamble Solution (GS) and Artificial Lysosomal Fluid (ALF) using dynamic light scattering (DLS). We found a large variability in the hydrodynamic diameter, with values less than 1 nm and greater than 5 μm. Furthermore, aggregation and disaggregation processes were recognized in GS and ALF, respectively. The results of this study increase the knowledge of the interaction between NPs and lung fluids, particularly within the alveolar macrophage region. Full article

The noise-like behavior of the geomagnetic anomalies observed in Tlamacas station (volcano Popocatepetl, Mexico), linked to the ionization produced by intensive radon release, are presented in the experimental part of this study. The magnetic field perturbations produced by charge spreading currents within the fair-weather electric field are considered in the theoretical model based on the electrode. The electric charges are generated by the air ionization due to radon emanation. The simulations demonstrated that the ionization of the air leads to magnetic field perturbations of about 0.001–0.1 nT in the ULF (ultra low frequency) range 10⁻³–10⁻¹ Hz. Magnetic field perturbations can be higher when the radon emanation occurs in a region with terrain irregularities. Full article

The complex nature of debris flows suggests that the pore-water pressure evolution and dewatering of a flowing mass caused by the high permeability of soil or terrain could play an essential role in the dynamics behavior of fast landslides. Dewatering causes desaturation, reducing the pore-water pressure and improving the shear strength of liquefied soils. A new approach to landslide propagation modeling considering the dewatering of a mass debris flow has drawn research attention. The problem is characterized by a transition from saturated to unsaturated soil. This paper aims to address this scientific gap. A depth-integrated model was developed to analyze the dewatering of landslides, in which, desaturation plays an important role in the dynamics behavior of the propagation. This study adopted an SPH numerical method to model landslide propagation consisting of pore-water and a soil skeleton in fully or partially saturated soils. In a two-phase model, the soil–water mixture was discretized and represented by two sets of SPH nodes carrying all field variables, such as velocity, displacement, and basal pore-water pressure. The pore-water was described by an additional set of balance equations to take into account its velocity. In the developed two-layer model, an upper desaturated layer and a lower saturated layer were considered to enhance the description of dewatering. This is the so-called two-phase two-layer formulation, which is capable of simulating the entire process of landslides propagation, including the large deformation of soils and corresponding pore-water pressure evolutions, where the effect of the dewatering in saturated soils is also taken into account. A dam-break problem was analyzed through the new and previously developed model. A flume test performed at Trondheim was also used to validate the proposed model by comparing the numerical results with measurements obtained from the experiment. Finally, the model was applied to simulate a real case lahar, which is an appropriate benchmark case used to examine the applicability of the developed model. The simulation results demonstrated that taking into account the effects of dewatering and the vital parameter of relative height is essential for the landslide propagation modeling of a desaturated flowing mass. Full article

A volcanic eruption can produce large ash clouds in the atmosphere around a volcano, affecting commercial aviation use of the airspace around the volcano. Encountering these ash clouds can cause severe damage to different parts of the aircraft, mainly the engines. This work seeks to contribute to the development of methods for observing the dispersion of volcanic ash and to complement computational methods that are currently used for the prediction of ash dispersion. The method presented here is based on the frequency of occurrence of the regions of airspace areas affected by ash emission during a volcanic eruption. Popocatepetl volcano, 60 km east of Mexico City is taken as a case study. A temporal wind analysis was carried out at different atmospheric levels, to identify the direction towards which the wind disperses ash at different times of the year. This information showed two different trends, related to seasons in the direction of dispersion: the first from November to May and the second from July to September. To identify the ash cloud and estimate its area, a set of 920 MODIS images that recorded Popocatepetl volcanic activity between 2000 and 2021 was used. These satellite images were subjected to a semi-automatic, digital pre-processing of binarization by thresholds, according to the level of the brightness temperature difference between band 31 (11 µm) and band 32 (12 µm), followed by manual evaluation of each binarized image. With the information obtained by the processing of the MODIS image, an information table was built with the geographical position of each pixel characterized by the presence of ash for each event. With these data, the areas around Popocatepetl volcano with the highest frequency of affectation by ash emissions were identified during the period analyzed. This study seeks to complement the results obtained by numerical models that make forecasts of ash dispersions and that are very important for the prevention of air navigation risks. Full article

Volcanic exposure implies multiple hazards for human settlements. The identification of the potential hazards that volcanic activity can entail is a challenge requiring assessing the specific situations that a determined place would face. Popocatépetl, a volcano in the centre of México, represents a significant hazard source, and it is located within a densely populated region with more than 20 million people. Despite the existence of a colour-based volcano alert level system for the current activity of the volcano, it is relevant to assess which local scenarios are more likely depending on numerous variables, namely, related to the distance from the volcano. A semi-quantitative analysis was carried out based on existing hazard maps and considering the probability of occurrence of volcanic explosivity, taking the settlement of San Pedro Tlalmimilulpan as a case study. This analysis led to a hierarchised rank of hazards, providing a basis for analysing multiple scenarios through failure mode and event analysis, failure tree analysis and event tree analysis. This process facilitates the contextualisation of the multiple challenges and potential chains of events that emergency actions, namely, emergency evacuations, would face. The analysis of the critical paths can help to identify critical aspects that could hinder the post-event response. Full article