This paper presents a comparative modeling and analysis of an induction furnace for melting aluminum (Al) and copper (Cu), focusing on their electromagnetic behavior and heating performance. The study employs ANSYS Maxwell software version 16.0 with the finite element method (FEM) to simulate eddy current generation, Joule heating, and current density distribution in the metallic workpieces. The effects of coil geometry, input current, and operating frequency (50–100 kHz) on heating efficiency and skin depth are investigated. Estimated heating times based on ohmic losses are provided, revealing significant differences between aluminum and copper due to their distinct electrical and thermal properties. The results demonstrate that higher frequencies concentrate heating near the surface, reducing skin depth, while copper exhibits more uniform heating than aluminum. These findings offer practical insights for optimizing induction furnace design and operation for different non-ferrous metals.
This study investigates how stratification—layering of particles of different sizes—affects porosity in granular sediment packings. While most existing porosity models are developed for well-mixed, homogeneous grain structures, natural riverbed sediments can be stratified, which may lead to significant deviations in porosity. To address this, a novel, cost-effective, and non-destructive laboratory method was developed to measure the vertical porosity distribution in stratified samples using glass beads. Results confirmed the presence of transition layers at the interface between coarse and fine sediments, where porosity follows a distinct trend of decrease and recovery. A Discrete Element Method (DEM)–based simulation model (<i>Particula 1.3</i>) was calibrated and validated against laboratory results, enabling broader parameter studies beyond the physical experiments. An improved algorithm based on a density threshold was also introduced to efficiently and objectively determine the transition layer extent in simulations. Empirical formulas linking transition layer thickness and porosity metrics to the grain-size ratio were derived, enabling the calculation of the average porosity of a stratified sample. Part I focuses on the experimental setup, model validation, and foundational insights into transition zone formation. A companion paper (Part II) will build on these results to develop predictive models for porosity in stratified sediment.
Sean Santellanes, Dara Goldberg, Pablo Koch
et al.
On October 19, 2020, the Mw7.6 Sand Point earthquake struck south of the Shumagin Islands in Alaska. Moment tensors indicate the earthquake was primarily strike-slip, yet the event produced an enigmatic tsunami that was larger and more widespread than expected for an earthquake of that magnitude and mechanism. Using a suite of hydrodynamic, seismic, and geodetic modeling techniques, we explore plausible causes of the tsunami. We find that strike-slip models consistent with the moment tensor orientation cannot produce the observed tsunami. Hydrodynamic inversion of sea surface deformation from deep ocean and tide gauge data suggest seafloor deformation more closely matches a megathrust, rather than a strike-slip, source. Static slip inversions, using sea level and Global Navigation Satellite System data, allow for a portion of co-seismic megathrust slip that can explain tsunamigenesis. Combining all available geophysical datasets to model the kinematic rupture, we show that considerable, relatively slow, megathrust slip is allowable in the Shumagin segment, concurrent with strike-slip faulting. We hypothesize that the slow megathrust rupture does not contribute much seismic radiation allowing it to previously go unnoticed with traditional seismic monitoring.
The Dangkhar Landslide is an extremely large landslide located in the Spiti Valley of Himachal Pradesh, India. The landslide is situated in a remote high mountain desert within the Tethys Himalaya at elevations between 3400 m and 5600 m. It is amongst the five largest continental landslides on earth, covering an area of approximately 54 km<sup>2</sup> and having an estimated volume of 15–20 km<sup>3</sup>. Geomechanical evaluations based on the block theory indicate that the Dangkhar Landslide formed as a result of unfavorable combinations of structural geological features and complex surface morphology. A massive kinematically removable block is created by a regional synclinal flexure that is crosscut and kinematically liberated by bounding side valleys. Three-dimensional block kinematics are necessary to permit the release of the giant block and its sliding along the synclinal flexure. Pseudostatic slope stability sensitivity analyses incorporating estimates of site seismicity and shear strength parameters suggest that earthquake shaking could have triggered instability if the static factor of safety was less than or in the range of about 1.5–1.9. Considering the glacial history of the region, ice debuttressing represents an additional potential triggering mechanism.
L. Wallberg, L. Wallberg, L. Suarez-Gutierrez
et al.
<p>The internal variability of European summer temperatures has been linked to various mechanisms on seasonal to sub- and multi-decadal timescales. We find that sub-decadal timescales dominate summer temperature variability over large parts of the continent and determine mechanisms controlling extremely warm summers on sub-decadal timescales. We show that the sub-decadal warm phases of bandpass-filtered European summer temperatures, hereinafter referred to as extremely warm European summers, are related to a strengthening of the North Atlantic Ocean subtropical gyre, an increase in meridional heat transport, and an accumulation of ocean heat content in the North Atlantic several years prior to the extreme summer. This ocean warming affects the ocean–atmosphere heat fluxes, leading to a weakening and northward displacement of the jet stream and increased probability of occurrence of high-pressure systems over Scandinavia. Thus, our findings link the occurrence of extremely warm European summers to the accumulation of heat in the North Atlantic Ocean and provide the potential to improve the predictability of extremely warm summers several years ahead, which is of great societal interest.</p>
Mohammad Taghi Farahnak, Mohammad Ali Afshar Kazemi, Ali Mohaghar
et al.
This research models and simulates the development of transmission capacity considering electricity supply and demand dynamics. After presenting a causal loop diagram and designing a stock and flow diagram, the model's validity is confirmed using validation methods for system dynamics models. The analysis then proceeds to scenarios for the total electricity demand in Iran. Firstly, the country's electricity demand structure is broken into industrial, household, agricultural, and other sectors. By studying consumption trends in each sector, linear and nonlinear regression are used to predict total electricity demand. Next, three scenarios - optimistic, moderate, and pessimistic - are defined in terms of electricity demand, and the required transmission capacity is calculated and designed for 400, 230, 132, and 63-66 kilovolt substations to cover and meet future electricity demand over twenty years. The research findings over a 20-year horizon indicate that in the moderate scenario, where electricity demand increases by 90 percent, the transmission capacity needs to increase by 106 percent to meet the demand. In the optimistic scenario, where electricity demand increases by 71 percent, the transmission capacity needs to increase by 85 percent. In the pessimistic scenario, where electricity demand increases by 110 percent, the transmission capacity needs to increase by 126 percent.
Dynamic and structural geology, Engineering (General). Civil engineering (General)
B. Rojo-Garibaldi, M. Contreras-López, S. Giannerini
et al.
<p>We carry out a nonlinear time series analysis motivated by dynamical systems theory to investigate the links between temperatures on the eastern South Pacific coast, influenced by the Humboldt Current System, and El Niño–Southern Oscillation (ENSO) events. To this aim, we use a set of 16 oceanic and atmospheric temperature time series from Chilean coastal stations distributed between 18 and 45<span class="inline-formula"><sup>∘</sup></span> S. The spectral analysis indicates periodicities that can be related to both internal and external forcing, involving not only ENSO, but also the Pacific Decadal Oscillation, the Southern Annual Mode, the Quasi-Biennial Oscillation and the lunar nodal cycle. The asymptotic neural network test for chaos based on the largest global Lyapunov exponent indicates that the temperature dynamics along the Chilean coast is not chaotic. We use local Lyapunov exponents to characterize the short-term stability of the series. Using a cross-entropy test, we find that two stations in northern Chile, one oceanic (Iquique) and one atmospheric (Arica), present a significant positive cross-dependence between local Lyapunov exponents and ENSO. Iquique is the station that presents the greater number of regional characteristics and correlates with ENSO differently from the rest. The unique large-scale study area, combined with time series from hitherto unused sources (Chilean naval records), reveals the nonlinear dynamics of climate variability in Chile.</p>
Data acquired by broadband seismic stations distributed around the world are used to document the exceptionally long duration signal from the tsunami-associated gravity wave that followed the January 2022 Hunga-Tonga eruption. The first arrivals of this wave, with a frequency of around 2 mHz, are recorded at the time the tsunami arrives to each station, but the highest recorded frequencies, which reach 40 mHz, arrive 5 days later at some sites, following the prediction of a gravity wave originating at the Hunga-Tonga region and traveling in deep water. This dispersive signal is detected in most of the stations located in the Pacific Ocean basin and its coasts, but also in the Indian Ocean, Antarctica, and some stations in North America located hundreds of kilometers from the coastline. The signal is compared with the data gathered after earthquakes that have produced large tsunamis, showing that the seismic records from the Hunga-Tonga eruption are very different. Following the hypothesis pointed out by Omira et al 2023, we propose that the origin of this exceptional characteristic is due to the interaction between the tsunami and atmospheric waves that travel a little faster.
This study constructs a preliminary inventory of landslides triggered by the MS 6.8 Luding earthquake based on field investigation and human-computer interaction visual interpretation on optical satellite images. The results show that this earthquake triggered at least 5 007 landslides, with a total landslide area of 17.36 km2, of which the smallest landslide area is 65 m2 and the largest landslide area reaches 120 747 m2, with an average landslide area of about 3 500 m2. The obtained landslides are concentrated in the IX intensity zone and the northeast side of the seismogenic fault, and the area density and point density of landslides are 13.8%, and 35.73 km−2 peaks with 2 km as the search radius. It should be noted that the number of landslides obtained in this paper will be lower than the actual situation because some areas are covered by clouds and there are no available post-earthquake remote sensing images. Based on the available post-earthquake remote sensing images, the number of landslides triggered by this earthquake is roughly estimated to be up to 10 000. This study can be used to support further research on the distribution pattern and risk evaluation of the coseismic landslides in the region, and the prevention and control of landslide hazards in the seismic area.
Geophysics. Cosmic physics, Dynamic and structural geology
Natural soils are often modelled as a continuum characterized by the composition of the soil, a particulate material. Yet, in situ, the fabric and structure of soil may govern its behavior. Discrete element modelling is used to simulate the composition of soil as a particulate material and develop fabric quantities. These quantities are presented as average quantities for a volume of particles. It is possible to use DEM to study the evolution of fabric at the particle level. This paper describes a state-of-the-art fabric term, referred to as geometrical stability index, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mo>ʎ</mo></semantics></math></inline-formula>, which can measure the contacts deviation of each particle from the most stable contacts arrangement during loading. The parameters required to define this new fabric term were attained from a designed algorithm. 2D discrete element method (DEM) biaxial test simulations were performed to validate the effectiveness of the geometrical stability index in defining the local instability. As the sample is loaded, a shear band is formed. The geometric stability index in that band increases relative to the surrounding relatively intact soil. Thus, a brittle failure is associated with an increase in the variation of inter-particle contacts from a stable configuration. The geometric stability index is able to model the development of discontinuities in a particulate material at the particle level. The DEM modelling results demonstrate the correlations between the new fabric term and the progressive of localized failure in densified particulate systems such as over consolidated clay, where the failure is a function of progressive development of local fissure spacing.