Juan Francisco Sánchez-Pérez

This paper presents an inverse problem protocol designed to estimate the explosive mass involved in accidental explosions by analyzing the observed effects on structures and individuals. Theoretical equations for calculating overpressure and momentum—which, although less accurate than finite element simulations, do not require significant computational resources—and the Probit methodology for damage quantification are widely employed. By applying both techniques, this study identifies the most suitable effects for applying the inverse problem, considering their distribution relative to distance and explosive mass. Mortality-related effects are considered unreliable due to their extremely narrow range, introducing significant uncertainty. However, eardrum rupture offers a broader distribution, although its practical application is complex due to the difficulties in determining both the distance to the population and the percentage of affected individuals. Conversely, structural damage to buildings proves to be the most accurate and reliable indicator, facilitated by GIS-based distance measurements and the clear categorization of damage levels. Finally, the use of a confidence interval in the inverse problem protocol allows for the filtering of highly biased data, ensuring that unreliable observations do not compromise the accuracy of the result. Furthermore, analysis demonstrates that a 90% confidence level minimizes relative error and improves robustness. In conclusion, a protocol is presented that allows the determination of the mass of the unstable substance involved in accidental explosions, specifying both the appropriate statistical indicators and the effects that are suitable for use in the inverse problem.

This paper presents an innovative approach to modelling the fiber optic fusion effect using the Network Simulation Method (NSM). An analogy between the heat conduction equations and electrical circuits is developed, allowing a complex physical problem to be transformed into an equivalent electrical system. Using NGSpice, thermal interactions in an anisotropic optical fiber under high optical power conditions are simulated. The methodology addresses the distribution of the temperature in the system, considering thermal variations and temperature-dependent material characteristics. In an NSM equivalent circuit, the effect of applying the spark is modelled by a switch that switches the spark-generating source on and off. It can be seen that temperature variation with time, or temperature rise rate (K/s), depends on the applied power. In addition, the mathematical method of nondimensionalization is used to study the real influence of each parameter of the problem on the solution and the relationship between the variables. Four optical fiber cases are analysed, each characterised by different areas and refractive indices, revealing how these variables affect the propagation of the melting phenomenon. The results highlight the effectiveness of the NSM in solving nonlinear and coupled problems in thermal engineering, providing a solid framework for future research in the optimisation of optical communication systems.

Road construction and maintenance are crucial for a functioning society, and achieving cost-effective and environmentally sustainable practices requires a deep understanding of road degradation processes. Temperature fluctuations and extreme temperatures are significant contributors to road surface deterioration, leading to issues such as cracking, rutting, and deformation, which not only reduce the road lifespan but also release fine particulate matter, posing environmental hazards. In this study, we develop detailed road surface temperature maps for Spain, using real-time weather and solar irradiation data from 46 evenly distributed meteorological stations. These maps provide hourly average road surface temperatures for each season and highlight extreme conditions during summer and winter, incorporating meteorological variables such as air temperature, wind speed, and relative humidity, showing that during winter, but particularly during summer, most of the territory is subjected to extreme temperatures. By visualizing thermal stress on road surfaces, the road surface temperature maps enable the identification of high-risk areas, supporting targeted maintenance, conservation efforts, and pollution mitigation, ultimately contributing to a more sustainable road infrastructure.

Hydrodynamic traffic models are crucial to optimizing transportation efficiency and urban planning. They usually comprise a set of coupled partial differential equations featuring an arbitrary number of terms that aim to describe the different nuances of traffic flow. Consequently, traffic models quickly become complicated to solve and difficult to interpret. In this article, we present a general traffic model that includes a relaxation term and an inflow of vehicles term and utilize the mathematical technique of nondimensionalisation to obtain universal solutions to the model. Thus, we are able to show extreme sensitivity to initial conditions and parameter changes, a classical signature of deterministic chaos. Moreover, we obtain simple relations among the different variables governing traffic, thus managing to efficiently describe the onset of traffic jams. We validate our model by comparing different scenarios and highlighting the model’s applicability regimes in traffic equations. We show that extreme speed values, or heavy traffic inflow, lead to divergences in the model, showing its limitations but also demonstrating how the problem of traffic jams can be alleviated. Our results pave the way to simulating and predicting traffic accurately on a real-time basis.

One factor affecting the stability of mining stockpiles is the moisture defined mainly by copper solution trapped in the porous by capillary. This moisture is not easy to remove if conventional methods are applied which use pressure or gravity as driving force. In the case of saturated or partially saturated soils with water, containing a large fraction of fine material, electroosmosis not only allows to reduce the humidity but also changes the structure, giving a higher strength and stability to the soils. Since the movement of the water, due to the electric gradient, is from the anode toward the cathode, the soil water content will decrease at the anode and will increase at the cathode. Water accumulated at the cathode then can be discharged by providing a drainage system at the cathode. This chapter presents theoretical and experimental aspects on electroosmotic drainage technique, based in works realized by the authors of this chapter. To explain the water flow through a mining residue containing a certain fraction of fine material and that in addition presents a high humidity, a model for the fluid flow in porous media is described here, taking into consideration two driving forces, defined by hydraulic and electric potentials.

The Burgers–Huxley equation is important because it involves the phenomena of accumulation, drag, diffusion, and the generation or decay of species, which are common in various problems in science and engineering, such as heat transmission, the diffusion of atmospheric contaminants, etc. On the other hand, the mathematical technique of nondimensionalisation has proven to be very useful in the appropriate grouping of the variables involved in a physical–chemical phenomenon and in obtaining universal solutions to different complex engineering problems. Therefore, a deep analysis using this technique of the Burgers–Huxley equation and its possible boundary conditions can facilitate a common understanding of these problems through the appropriate grouping of variables and propose common universal solutions. Thus, in this case, the technique is applied to obtain a universal solution for Dirichlet and symmetric boundary conditions. The validation of the methodology is carried out by comparing different cases, where the coefficients or the value of the boundary condition are varied, with the results obtained through a numerical simulation. Furthermore, one of the cases presented presents a boundary condition that changes at a certain time. Finally, after applying the technique, it is studied which phenomenon is predominant, concluding that from a certain value diffusion predominates, with the rest being practically negligible.