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A multiple quantum well (MQW) transistor vertical-cavity surface-emitting laser (T-VCSEL) is designed and numerically modeled. The important physical models and parameters are discussed and validated by modeling a conventional VCSEL and comparing the results with the experiment. The quantum capture/escape process is simulated using the quantum-trap model and shows a significant effect on the electrical output of the T-VCSEL. The parameters extracted from the numerical simulation are imported into the analytic modeling to predict the frequency response and simulate the large-signal modulation up to 40 Gbps. [ABSTRACT FROM AUTHOR]

Historical masonry structures are the most important features that distinguish our cultural heritage, from here comes the importance of protection this type of masonry structures from collapse under earthquakes effect or other dynamic loading such as blast loading. Therefore, Seismic Base Isolation is used to reduce earthquakes damages and protect structures from collapse. This paper aims to study the Effect of Seismic Base Isolation, using High Damping Rubber Bearing (HDRB) on Existing Masonry Structures subjected to dynamic loads such as earthquakes, through utilizing numerical modeling of masonry structures. This paper includes definition of seismic base isolation mechanical characteristics, and definition of numerical modeling approaches for structural masonry analysis. The studied masonry structure is the old AWQAF Directorate Building in Aleppo, which is islamic government building affiliated to the Syrian Ministry of AWQAF; In order to perform the numerical modeling, equivalent masonry properties used for this structure were also determined. This structure was analyzed applying nonlinear dynamic analysis-time history method, and reanalyzing it by using seismic base isolation, type HDRB applying the same method. The results of the two analyses were discussed and compared, and the conclusions of this paper showed reduction in shear force when using seismic base isolation, and reduction in stresses that appear in structure because the stresses are located in the level of base isolation system. [ABSTRACT FROM AUTHOR]

Seismic damage due to pounding between adjacent buildings is often observed after significant earthquake events in old urban centers and globally recognized as a potential trigger for complete collapse. This is relevant for unreinforced masonry (URM) structures, which are particularly vulnerable to horizontal actions and seldom feature appropriate seismic detailing. Quantifying pounding damage between dynamically interacting URM buildings, however, is a challenging task, the details of which are difficult to simulate through analytical modeling alone. Numerical simulation of pounding failures, on the other hand, involves impact, separation and re-contact phenomena that often require advanced 3D micro-modeling strategies, often entailing a high computational expense that is not feasible when modeling the coupled seismic response of multiple buildings. To enable simulation of pounding damage in URM structures with relatively low computational cost, this paper investigates the use of a recently developed Macro-Distinct Element Model (M-DEM) approach. To this end, a M-DEM is herein used to simulate the shake-table biaxial pounding response of two dynamically interacting stone building prototypes, tested within the framework of the Seismic Testing of Adjacent Interacting Masonry Structures project sponsored by the Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe. Numerical results were obtained before the experimental test and then subsequently evaluated against the experimental results. The M-DEM predictions satisfactorily reproduced the measured base shear and interface opening, although they underestimated the floor displacement demand, especially in the transversal direction. Building on these encouraging outcomes, a post-test refined M-DEM model was also developed, and results are discussed alongside the lessons learned and proposed enhanced strategies to improve the quality of predictions. [ABSTRACT FROM AUTHOR]

The Lax–Friedrichs scheme is traditionally considered an alternative to the Godunov scheme, since it does not require solving the Riemann problem. In the equations of special relativistic hydrodynamics, the speed of light is a natural limitation of the wave propagation speed. The use of such an upper estimate of the slopes of characteristics in the schemes of Roe, the Rusanov type, or the Harten–Lax–van Leer family leads to a construction equivalent to the Lax–Friedrichs scheme. Due to the absolute robustness of the scheme, a number of software implementations have been developed on its basis for modeling relativistic gas flows. In this paper, we propose a piecewise parabolic reconstruction of the physical variables to reduce dissipation of the numerical method. The use of such a reconstruction in the Lax–Friedrichs scheme allows us to obtain an absolutely robust simple scheme of high-order accuracy on smooth solutions and with small dissipation at the discontinuities. The computational experiments carried out in the article confirm these properties of the scheme. [ABSTRACT FROM AUTHOR]

Planar erosion is an important mode of soil erosion, which occurs in the process of loess slope erosion, gully erosion, and cave erosion. It is of great significance to understand the characteristics and mechanism of planar erosion to reveal the mechanism of loess erosion and the prevention and treatment of soil and water loss. In this paper, a series of loess planar erosion tests have been carried out through self-developed large-scale loess scour instrument. The erosion process and stage characteristics of subsurface erosion under different conditions have been analyzed and summarized, and the internal mechanism of the loess planar erosion process in different erosion characteristic stages has been revealed. Furthermore, based on the special "core (powder) + coat" microstructure characteristics of loess, a numerical model of inter particle linkage was established to characterize the characteristics of loess microstructure and anti-erosion properties. The numerical simulation results carried out based on the numerical model of inter particle linkage established in this paper are in good agreement with the main results of the physical simulation of planar erosion. The results all show that the loess planar erosion at the scale of large test blocks can be divided into three characteristic stages: uniform planar erosion stage, micro gully erosion stage, and collapse failure stage. This indicates that the fluid–solid coupling simulation method of CFD–DEM proposed in this paper has high simulation accuracy and has great application potential in the research and application of loess erosion. This provides a new and feasible idea for the study of loess slope erosion and hydraulic loss control on the Loess Plateau, which is worthy of further promotion. [ABSTRACT FROM AUTHOR]

Low-temperature concrete pouring on dams causes sudden temperature drops on the surface of the previously poured concrete, thus inducing thermal cracks. In this study, a field test and a numerical calculation were performed on the temperature drop effect caused by low-temperature pouring to prevent thermal cracks in concrete dams. Firstly, a small spatial-scale temperature-gradient monitoring scheme was designed for concrete dams based on the distributed temperature sensing (DTS) system. Secondly, a field test was conducted during the construction period of the Baihetan extra-high arch dam using this scheme, analyzing the temperature response of low-temperature pouring. Finally, a numerical simulation model was established on the temperature field and stress field of the dam, studying the temperature drop effect caused by low-temperature concrete pouring under different construction conditions and its countermeasures. The results indicate that the temperature monitoring scheme proposed in this paper could effectively capture the temperature drop effect at a small-spatial scale caused by low-temperature pouring. This effect, as a negative impact on crack prevention of dam concrete, is effectively weakened using uniform surface-flowing water cooling with a temperature of 22–24°C. [ABSTRACT FROM AUTHOR]

This paper analyzes processes in the combustion chamber of spark ignition engine under direct jet injection of hydrogen during the compression stroke. Numerical modeling is used to study the features of mixing hydrogen with air and its combustion after ignition from a spark at the instant when the piston reaches the top dead center (TDC). The combustion regimes that develop when the injection pressure is varied from 20 to 140 atm, and the start of injection, from 180° to 45° of the crank angle (CA) before the TDC, are considered. In all cases the mass of hydrogen necessary for the formation of a stoichiometric mixture with air during injection into the combustion chamber is supplied. It is found that the most uniform mixture at the time of ignition is formed with advanced injection (180°–135° of the CA before the TDC) at a relatively low pressure (20–60 atm). The ignition of a uniform mixture in the conditions considered leads to detonation regime of combustion. A lower degree of uniformity of the mixture corresponds to a slow, deflagration combustion regime. It is important to note that nonuniformity of the mixture determines the ambiguity of the formation of a certain combustion regime, depending on the local mixture composition in the vicinity of a spark. At the same time, the slowest combustion regime provides the maximum hydrogen combustion incompleteness, up to 8.2%. Generally, the considered ranges of injection pressure and start of injection lead to satisfactory levels of incompleteness of hydrogen combustion of less than 4%. [ABSTRACT FROM AUTHOR]

This paper studies the numerical analysis of the gaseous combustion process in a channel with a hydrogen-air mixture with the inflow of a fresh mixture seeded with microdroplets of water. The dynamics of microdroplets are described in the Lagrangian approximation, which makes it possible to identify the role of the local interaction between the droplets and the flame front. It is shown that the impact of droplets on the front can provoke the generation of disturbances of the flame front and intensify the development of the front's instability, thereby causing an integral increase in the combustion rate. Using the spectral analysis of the structure of the front in the presence of microdroplets, the dynamics of the development of individual harmonics of the front's disturbances is analyzed and the mechanisms of the evolution of the flame front under the influence of microdroplets of water are identified. [ABSTRACT FROM AUTHOR]

Bimslopes are slopes underlain by block-in-matrix rocks/soils (bimrocks/bimsoils), which are heterogeneous geomaterials with complex behavior. Abundant uncertainties in the mechanical, spatial, and geological nature of bimslopes make it difficult to estimate stability conditions of bimslopes. In this paper, some factors affecting the stability of bimslopes are investigated using the finite-element method. The main contributory factors include Volumetric Block Proportion (VBP), the inclination of blocks, and the strength of matrix/block interfaces. By performance of sensitivity analysis on these factors, a statistically significant equation was obtained to estimate the safety factor of bimslopes using the multivariate regression method. The influence of block configurations and groundwater levels on the stability of bimslopes was then investigated to more confidently use the multivariate equation. Finally, to check the validity of procedures presented in this paper, a real failed bimslope in the Sungun mine (Iran) was investigated. The acceptable results from the Sungun analysis demonstrated the safety factor of bimslopes can be estimated using the practical solution presented in this paper. Highlights: Development of more than 1300 numerical models to analyze the key factors affecting the stability of block-in-matrix slopes (bimslopes). Investigation of the influence of volumetric block proportion, the inclination of blocks, and strength of matrix/block interface on the safety factor of bimslopes. Consideration of the substantial uncertainties affecting the analysis of bimslopes. Presentation of the results of research in the form of applied schemes and tables. Provision of a practical procedure and equation for estimating the safety factor of bimslopes. [ABSTRACT FROM AUTHOR]

In this study, geomechanical behavior of fractures and faults in rocks as a saturated deformable discrete fracture-porous medium has been evaluated using coupled fluid flow-geomechanics numerical modeling. The purpose of this paper is to observe and evaluate the effects of fractures and faults on the pore pressures during fluid flow through reservoirs. This issue involves solving the equations that have been derived from the Biot consolidation theory such as fluid mass balance equation, Darcy law and momentum balance equations. Govern coupled equations were solved using the standard Galerkin finite element method for continuous porous medium. Elements called "zero-thickness elements" were also used to discretize the fault as a discontinuous part of the porous medium. In compared with the previous and similar methods, the method introduced in this paper, made modifications in either the choice of the element and the method of solving the governing equations. The main advantage of this paper is providing clear precise formulations of the double node zero-thickness element in hydro-mechanical modeling of fractures and faults. Verification of the proposed process and models presented in this paper were done by providing three index problems which their analytical and numerical solutions are available. The results of our model provide a good agreement to these reference solutions which indicates the accuracy of the method presented in this paper. [ABSTRACT FROM AUTHOR]

Numerical simulation of radon migration in fractured rock masses is crucial for environmental radon pollution protection, radon tracing technology and the co-exploitation of coal and uranium resources. This paper proposed a novel model based on a fractal discrete fracture network (DFN) to simulate radon migration in fractured rock masses. The paper provided a detailed method for determining the locations of three-dimensional fractures using the multiplicative cascade process. The governing equations for radon migration in fractures and the rock matrix were established and numerically solved using the finite element method. The study developed open-source software DFNRn (Discrete Fracture Network model for Radon migration), which was publicly available on GitHub. The software simulated radon migration in a fractured rock mass with a domain size of 100 m. The results demonstrate that fluid convection in fractures drives radon migration, which is dominant compared to the diffusion process. The accuracy of our proposed model was verified by comparing it with the measured data of the fractured rock. Furthermore, the study investigated the relationship between the percolation threshold of the fracture density P 32 ′ and the key parameters of the DFN. The results show that P 32 ′ decreased with the fractal dimension Df (1.4 ≤ Df ≤ 1.9) and normalization constant α (1.4 ≤ α ≤ 1.8) and is not correlated with the length exponent a (1.2 ≤ a ≤ 2.8). P 32 ′ decreased with the mean orientation angle and has no correlation with the Fisher constant. The radon source term of the rock matrix has the greatest impact on radon migration in fractured rock masses compared to the radon diffusion coefficient and permeability. Highlights: A new approach is proposed to model radon migration in fractured rock masses. An open-source software DFNRn was developed and is publicly available on GitHub. The procedure of the multiplicative cascade method in 3D space is given in detail. [ABSTRACT FROM AUTHOR]

One of the countries that constantly aim to develop a strategy for the exploitation of solar energy is Algeria, given the capabilities that make it a pioneer in this field. In this paper, we chose Oued El Keberit (OKP) Photovoltaic Plant located in the city of Souk-Ahras, eastern Algeria. The plant has a capacity of 15 MW. We focused on the solar panel array section of the station, specifically examining the performance of one of the subfields in this plant throughout the year under various outdoor conditions, beyond the Standard Test Conditions (STC) case. The study focused on factors that are known. Using a real data presented by the measurement station of the OKP photovoltaic power plant, numerical modeling and simulation of a PV station subfield were performed on the PV array for one subfield of the PV station using MATLAB Simulink. The results show how radiation intensity and temperature, whether low or high, affect the short-circuit current, open-circuit voltage, fill factor, and efficiency of the PV system. Notice that the level of radiation acts on the opposite of two important factors. The FF was at its lowest value in summer, but the efficiency is at its maximum value. Then, the FF in winter reaches its maximum, but efficiency is the lowest value. This means that they have an opposite relationship. On the other hand, the temperature affects the opposite way with open-circuit voltage especially when the temperature is above 25°C. [ABSTRACT FROM AUTHOR]

The average-derivative optimal method (ADM) is widely applied in frequency-domain forward modeling for its high accuracy and simplicity. Since tuning weighted coefficients can suppress the numerical dispersion, it is extremely important to adopt a suitable optimization algorithm to determine the ADM coefficients. To date, most schemes associated with the ADM have adopted the conventional local optimization algorithms, which are sensitive to the initial value and easy to converge on local optimum. The motivation of this paper is to derive new and more accurate ADM coefficients for 2D frequency-domain elastic-wave equation by the global optimization algorithms, which can escape from the local optimum with a certain probability. We adopt simulated annealing (SA) and particle swarm optimization (PSO) algorithms for global optimization and numerical modeling. Compared with the conventional local optimization algorithm, the global optimization algorithms have smaller phase errors, especially for S-wave phase velocity. Numerical examples demonstrate that the global optimization algorithms produce more accurate results than the local optimization algorithm. [ABSTRACT FROM AUTHOR]

Transit observations of exoplanets make it possible to measure temperature and relative abundance of various elements in their atmospheres. The infrared line of metastable helium HeI 10 830 Å is widely used to study the atmospheres of exoplanets by the transit absorption method. The emission spectra of stars have a significant impact on the physical and chemical parameters of the upper layers of the atmospheres. In this paper, we consider the features of absorption in the helium line for stars of different spectral classes by numerical simulation. The results show the key role of the star's emission spectrum in the formation of the upper atmosphere and in the amplitude of transit absorption of exoplanets in the HeI 10 830-Å line. [ABSTRACT FROM AUTHOR]

This paper presents the experimental and numerical results of studying the growth dynamics of the deterministic and given initial perturbations defined in a certain way. The formation, growth, and further evolution of inhomogeneities of the contact boundary occurs due to the development of the Rayleigh–Taylor instability (RTI) at the gas-liquid interface, and in particular (in this study), the air-water interface. The significant difference in the densities of the selected substances leads to a noticeable slowdown in the dynamics of the Kelvin–Helmholtz instability (KHI), which is responsible for the formation of mushroom-like structures, and, as a result, to the longer growth of water jets and the later moment of their destruction and transition to mixing. In this study, a quantitative comparison of the physical data recorded on the original experimental setup, which is described in this paper, with the calculated data obtained using various numerical methods is carried out. The numerical modeling is based on a complete 2D hydrodynamic model for describing the dynamics of the development of the RTI. The surface tension (water-air) and viscosity (water or air) are neglected in this study. The parameters of the development of the instability measured in the experiment and found in the calculations indicate satisfactory agreement between the obtained data. The quantitative results presented in this study justify the use of the classical hydrodynamics model to describe the movements of liquid and gas observed in this experiment and the fairly accurate numerical implementation of the corresponding model in the difference methods used here. The investigation of the development of turbulent mixing depending on well-defined initial conditions and the new regularities of the laws of mixing of the media of different densities that arise in this case is an important element in the study. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper describes a continuous numerical model of polluted groundwater plumes near the LRW storage reservoirs Lake Karachay and Staroye Boloto of Mayak Production Association. This model, developed by Gidrospetsgeologiya, is based on the long-term monitoring of data obtained by Facility-Focused Monitoring System (FFMS). The model is regularly updated as the FFMS database is augmented, new data of engineering-geological and hydrogeological surveys are obtained, and new tasks are set to assess the hydrogeological safety of nuclear facilities at the industrial site of Mayak Production Association. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Intense methane emission from permafrost soil into the atmosphere has long been observed in Arctic shelf and coastal zones. Due to the potential danger of this phenomenon for the environment and infrastructure, there is a need for periodic monitoring of gas pockets, including by means of land seismic exploration. In the present paper, this process is studied using numerical simulation methods. In order to reflect the main specific features of the region, a model of layered permafrost sandy soil with curved boundaries between the layers is constructed. Vertical and horizontal gas migration is represented by an increase in the number of methane reservoirs. The hyperbolic equations of linear elasticity are used as a governing system. The problem is solved by applying the grid-characteristic method in the two-dimensional case. The elastic parameters of the layers are specified in each grid cell. Wave structures exhibited by the resulting synthetic wave patterns and seismograms are analyzed in detail, allowing the direction of gas migration to be determined. The results can be used to interpret similar in situ measurements. [ABSTRACT FROM AUTHOR]

Modern conditions of mineral deposit development are characterized by more stringent requirements as to the environmental impacts of production and the increased volume of blasting operations near populated areas. The importance of the study is due to the need of developing energy-efficient technologies for crushing rocks, finding safe ways to intensify the coal degassing processes and reducing the intensity of methane inflow into the mined-out space. The Smoothed Particle Hydrodynamics numerical method used in this work allows adequately calculating nonlinear dynamic problems arising during blasting development of mineral deposits, while the use of most other computer modeling methods to solve these problems causes significant computational difficulties. The paper presents the results of a study of the nature of variations in the rock displacement velocity and the stresses and parameters of the radial crack propagation zone from the distance to the charge during blasting operations in monolithic and fractured massifs. [ABSTRACT FROM AUTHOR]

Rock anchors, which can withstand substantial forces and are essential for securing the foundations of the built environment, can fail due to steel tensile failure, bond detachment, or rock mass fracturing through uplift. In this study, uplift failure of the rock mass surrounding rock anchors was simulated using both physical and numerical models. The physical models used a specially designed testing rig with predefined sizes and different joint layouts to simulate rock mass uplift failure. The numerical models were calibrated using the physical models and used to investigate scenarios involving increased complexity and greater depths. This paper presents the load distribution within rock masses with orthogonal joints when exposed to an anchor load. Extensive analysis of the numerical models revealed that symmetrical load arches were induced in rock masses that contained a joint set oriented parallel to the loading direction. However, joints that were obliquely oriented relative to the anchor axis induced asymmetrical load arching. The greatest displacement occurred in the direction parallel to the joint set with the smallest angle to the anchor loading axis. Large-scale models with zero or near-zero in situ horizontal stress revealed that the load capacity in a rock mass with continuous vertical joints was relatively low, especially when compared to rock masses with discontinuous vertical joints. It was observed that the uplift capacity of the rock mass around an anchor decreased if the load arches of adjacent anchors overlapped; consequently, a decrease in anchor spacing was found to correspond to a decrease in uplift capacity. Highlights: Symmetrical load arches are induced within a rock mass if the joint sets are oriented parallel to or close to parallel to the anchor axis. An oblique orientation of the joints relative to the anchor axis results in asymmetrical load arching in the rock mass when the anchor is loaded. Rock masses with continuous vertical joints have a low load capacity, especially compared to rock masses with discontinuous vertical joints. In a row of rock anchors, the rock mass uplift capacity of individual anchors is decreased if the anchor spacing is too low. [ABSTRACT FROM AUTHOR]

The aim of this paper is to perform a hydrodynamic analysis of the fluid flow around a symmetrical 3D hydrofoil on the physical laboratory model HM133 and to show the formation of the boundary layer and the separation point on the observed body. The analysis is performed in such a way that the geometric body within the measuring section of the physical model HM133 rotates around its vertical axis due to the fluid flow (water), resulting in a various potential view in front of and behind the observed body. The investigations were carried out in Hydrotechnical Laboratory Practicum at the Faculty of Civil Engineering, University of Rijeka. The paper covers the field of real fluid dynamics, which includes a description of laminar and turbulent flow on a plane surface and the formation of a boundary layer and separation point on the observed geometric body. In this segment, both the boundary layer and its properties have been analyzed in detail. The hydrodynamic analyses based on the tested submodels of hydrofoil of the physical model HM133 were validated and verified with the Computational Fluid Dynamics (CFD). This is based on the development of commercial numerical models in the computer program ANSYS Fluent 2020R1. [ABSTRACT FROM AUTHOR]

High-frequency precipitation variance is calculated in 12 different free-running (non-data-assimilative) coupled high resolution atmosphere–ocean model simulations, an assimilative coupled atmosphere–ocean weather forecast model, and an assimilative reanalysis. The results are compared with results from satellite estimates of precipitation and rain gauge observations. An analysis of irregular sub-daily fluctuations, which was applied by Covey et al. (Geophys Res Lett 45:12514–12522, 2018. https://doi.org/10.1029/2018GL078926) to satellite products and low-resolution climate models, is applied here to rain gauges and higher-resolution models. In contrast to lower-resolution climate simulations, which Covey et al. (2018) found to be lacking with respect to variance in irregular sub-daily fluctuations, the highest-resolution simulations examined here display an irregular sub-daily fluctuation variance that lies closer to that found in satellite products. Most of the simulations used here cannot be analyzed via the Covey et al. (2018) technique, because they do not output precipitation at sub-daily intervals. Thus the remainder of the paper focuses on frequency power spectral density of precipitation and on cumulative distribution functions over time scales (2–100 days) that are still relatively "high-frequency" in the context of climate modeling. Refined atmospheric or oceanic model grid spacing is generally found to increase high-frequency precipitation variance in simulations, approaching the values derived from observations. Mesoscale-eddy-rich ocean simulations significantly increase precipitation variance only when the atmosphere grid spacing is sufficiently fine (< 0.5°). Despite the improvements noted above, all of the simulations examined here suffer from the "drizzle effect", in which precipitation is not temporally intermittent to the extent found in observations. [ABSTRACT FROM AUTHOR]

The applications of numerical simulation modeling such as assisted history matching, production optimization, and reservoir performance forecasting usually lead to significant time, computer resources, and accordingly huge associated costs. To overcome these circumstances, proxy modeling is the suggested approach to deliver a cheap alternative and approximate nonlinear oil and gas reservoir responses such as recovery factor and reservoir operating parameters and characteristics. Proxy modeling is considered a powerful tool for optimization and uncertainty analysis alike. Conventionally, the reservoir simulation is solved by tuning selected uncertain reservoir parameters one at a time. While, the most important feature of proxy modeling is the ability to determine the combined effect of uncertain parameters at the same time. Petroleum engineering field usually requires a wide variety of parameter estimation problems, and proxy modeling can satisfy this demand. Proxy modeling can be developed based on different methods; the current paper presents a comprehensive review of the methods of developing of proxy modeling and their applications in reservoir simulation since proxy modeling is becoming more widely used as a simplify highly complex substitution to reservoir simulation with reasonable accuracy. This article reviews the methods used in recent years to develop proxy models as a successful replica of complex numerical flow simulation models. This will shed the light of different proxy models, their uses, and how to judge on their efficiencies. [ABSTRACT FROM AUTHOR]

In many catchments prone to debris flows, prevention structures such as check dams and retention basins have been installed to prevent debris flows from impacting the nearby infrastructures. The SPH model adopting the Herschel–Bulkley–Papanastasiou (HBP) constitutive law has shown good potential in modeling the interaction between debris flow and prevention structures. However, the accuracy of this model is not fully satisfactory when modeling the deposition process of debris flow, because the original HBP law is a viscoplastic model which does not consider frictional dissipation. Therefore, in this paper, we proposed a novel SPH model for analyzing the interaction between debris flow and prevention structures, by incorporating a modified HBP law with frictional dissipation into the original SPH model. The proposed model is validated by column collapse and flume benchmark experiments first and then utilized to analyze a real debris flow and its interaction with the prevention structures in the Cancia catchment in northern Italian Alps. The results of the column collapse experiment show that our model exhibits a better performance in simulating the collapse process compared with the original SPH model, and the simulation results of the sand flume test illustrate that the proposed model can accurately predict the impact force of debris flow on the prevention structure. The simulation results of the Cancia debris flow demonstrate that the check dams can dramatically diminish the discharge and the frontal flow velocity of the debris flow, and the peak impact force of debris flow generally decreases with gentler channel slope. Furthermore, various prevention structures show different interaction mechanisms with debris flows: the flat deposition platform mainly dissipates the kinetic energy of the flow, the check dam mainly reduces the peak discharge of the debris flow and intercepts the debris mass, and the retention basin at the outlet contributes to the deposition of debris flow. The proposed novel SPH model is helpful for guiding the optimization design of multiple prevention structures in debris flow gullies. [ABSTRACT FROM AUTHOR]

The paper presents a reconstruction of metamorphic stages in the Moren and Erzin metamorphic complexes in the Khan-Khuhay block of northern Mongolia. This reconstruction is used as a basis for discussing the general geodynamic history of the Sangilen terrain of the Tuva–Mongolia Massif. The calculated clockwise P–T path shows two stages of metamorphism: (1) collisional metamorphism at 9 kbar, 740°C; and (2) metamorphism related to a regional magmatic episode, at 6–7 kbar, 860–880°C. Geochemical and petrological features of rocks in the Khan-Khuhay block demonstrate that these rocks are similar to those of the metamorphic block of Western Sangilen in southeastern Tuva. Quartz monzodiorite intrusive bodies first found in the Khan-Khuhay block show geochemical features similar to those of Ordovician gabbro–monzodiorite intrusions in the western Sangilen. The Khan-Khuhay quartz monzodiorite intrusions may be small apophyses of an intermediate deep crustal magma chamber and could be a probable thermal source of metamorphic stage M2 in the Khan-Khuhay block. The numerical thermo-mechanical model of metamorphism in the Khan-Khuhay block explains the heating in the thickened crust during collision by a higher (relative to the average crustal) radiogenic heat production of 1.52 μW/m3. Computer modeling indicates that the P–T parameters of the second metamorphic stage could be reached only with the involvement of magmatic heat from the monzodiorite intrusion. The P–T metamorphic parameters calculated using mineral thermobarometry, similarity of geochemical characteristics, and results of the thermomechanical modeling allow us to conclude that the Erzin and Moren complexes have undergone a joint tectono-metamorphic evolution. [ABSTRACT FROM AUTHOR]

In this study, a new paradigm compared to traditional numerical approaches to solve the partial differential equation (PDE) that governs the thermo-poro-mechanical behavior of the shear band of deep-seated landslides is presented. In particular, this paper shows projections of the temperature inside the shear band as a proxy to estimate the catastrophic failure of deep-seated landslides. A deep neural network is trained to find the temperature, by using a loss function defined by the underlying PDE and field data of three landslides. To validate the network, we have applied this network to the following cases: Vaiont, Shuping, and Mud Creek landslides. The results show that, by creating and training the network with synthetic data, the behavior of the landslide can be reproduced and allows to forecast the basal temperature of the three case studies. Hence, providing a real-time estimation of the stability of the landslide, compared to other solutions whose stability study has to be calculated individually for each case scenario. Moreover, this study offers a novel procedure to design a neural network architecture, considering stability, accuracy, and over-fitting. This approach could be useful also to other applications beyond landslides. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research paper focuses on the thermo-hydro-mechanical (THM) modeling of brine migration in a heated borehole test conducted as part of the ongoing Brine Availability Test in Salt (BATS) at the Waste Isolation Pilot Plant (WIPP) in New Mexico. It is a component of the international collaboration project DECOVALEX-2023 (DEvelopment of COupled models and their VALidation against EXperiments), which aims to understand the THM processes governing brine flow in heated rock salt repositories through collaborative analysis by multiple research teams. Using the TOUGH–FLAC simulator, THM simulations were performed and compared with data from the BATS phase 1a. This experiment involved two identical horizontal-borehole arrays, one heated and one serving as a control, both equipped with sensor arrays. Analysis of measurements revealed water flow rate surges during heater power transitions, with the highest jump observed during cooling. Acoustic emission activity exhibited distinct patterns in response to heater power changes, suggesting that damage to rock salt is particularly pronounced during the cooling phase. The THM simulations successfully captured these phenomena, highlighting the significance of thermal effects, brine migration, and mechanical behavior in predicting brine availability in heated and damaged rock salt. Our modeling also revealed the critical interplay between heating and cooling-induced damage and its influence on flow properties, particularly affecting brine inflow estimation. Notably, we found that cooling-induced brine inflow spikes result from increased permeability due to tensile dilatancy. These findings have important implications for the development of robust containment strategies and enhance our understanding of the complex processes involved in repository performance. Highlights: Numerical modeling study accurately replicates the thermal-hydromechanical behavior of rock salt surrounding a heated borehole. Jumps in brine flow rate during transitions in heater power are observed, with the highest jump during cooling. Acoustic emission patterns suggest pronounced damage to rock salt during the cooling phase. Thermal pressurization and tensile-induced damage are identified as the primary contributors to brine inflow spikes. Findings improve predictions of brine availability, aiding the development of robust containment strategies for radioactive waste disposal. [ABSTRACT FROM AUTHOR]

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Residual stresses refer to those stresses from sources other than contemporary tectonic forces that are locked within the rock formation. These stresses could develop and be stored within the rock during the cooling process of rock formation, metamorphism periods, previous tectonic activities, and other deformation phenomena. If relieved, by any excavation activity, for example, they can cause immediate or time-dependent (or both) deformations due to strain relaxation. If such stresses existed in any high-strength unfractured rock formations (such as a metamorphosed iron formation) in the path of an exploration core drilling, these strain relaxations could be large enough to break up the core into small pieces, reducing the rock quality designation (RQD) values even down to zero. If these stresses exist and are ignored, the RQDs from the coring could be very misguiding which results in over-designing and unnecessarily increased time and expenses of projects. In this paper, a numerical modeling approach was used to investigate a case study where an RQD of zero was reported for a shallow high-strength unfractured rock formation in Michigan. As the geologic data indicate this formation is not fractured at all, the zero value of RQD could be the result of core damage during drilling. The results of the numerical modeling conducted in this study confirmed that the release of locked-in residual stresses during the drilling process could explain the observed core damage and observed zero value for the RQD. [ABSTRACT FROM AUTHOR]

The resistance to liquefaction of soils can be significantly increased by slightly reducing the degree of saturation. Many experimental studies demonstrated that the augmented compressibility of the pore fluid mixture composed by entrapped bubbles within a continuous fluid phase reduces the amount of seismically induced excess pore water pressure. On the contrary, interpretation through constitutive models of the cyclic response of nearly saturated soils, often referred to as gassy soils, is by far less explored in the literature. This paper addresses this topic by considering the gas–water mixture as a homogeneous equivalent fluid whose compressibility has been used along with the elastoplastic constitutive model formulated by Dafalias and Manzari (2004). The model has been calibrated on the experimental data obtained from monotonic triaxial tests on saturated sandy soils and then validated with the results of cyclic triaxial tests on saturated and non-saturated liquefiable sandy soils. The selected calibration has been used to perform parametric analyses by varying the initial conditions of the soil (i.e., the relative density and degree of saturation), thus further emphasizing the beneficial effect of quasi-saturated fluid to delay the onset of liquefaction instabilities. [ABSTRACT FROM AUTHOR]

The fractures network generated during the excavation of underground research facilities can induce stress redistribution and alteration of flow and transport properties, becoming preferential paths for releasing radionuclides into the host rock. Nevertheless, in the long term, the fracture can be sealed through the resaturation of water coming from the rock as a function of its self-sealing potential. Despite the large number of experimental studies that have proven the self-sealing capacity of clay rocks, very few attempts have been made to describe and predict the phenomenon numerically. This may be due to the difficulty of measuring the initial hydro-mechanical conditions. Besides, samples artificially fractured in the laboratory can be disturbed by the preparation process itself, which can alter the hydro-mechanical state. This paper addresses that issue by bridging the gap between experiments and numerical modeling. Representative experimental tests performed on Callovo–Oxfordian Claystone (COx) are used to offer a hydro-mechanical fracture law taking into account the self-sealing capacity of the material. Implementing such a model in a finite element code allows its validation through comparison with laboratory tests. Furthermore, the role of the initial fracture size and the evolution of water permeability during the wetting/drying process is investigated. Due to its transmissivity, injected water can penetrate the rock, initially reaching the damaged zone around the fracture before spreading through the entire sample. This progression is accounted in the constitutive equation and represented numerically. Nevertheless, a larger initial crack leads to reduced recovery rates. These results match the experiments, offering a valuable perspective in the modeling of self-sealing in in situ conditions. [ABSTRACT FROM AUTHOR]

Particulate isotopic analysis in nuclear forensics has developed rapidly during the past two decades due to technical advances in determining the isotopic composition of individual particles. This paper introduces basic statistical concepts that can be applied by analysts to understand the importance of statistical adequacy when interpretating particle data. While these basic statistical methods provide a useful point-of-entry to particle data analysis, more sophisticated statistical and modeling approaches are needed to extract maximal information from such datasets in the future. [ABSTRACT FROM AUTHOR]

A new physical and mathematical formulation for the extinguishing of a forest fire with an inhibitor solution distributed using an explosive charge is proposed in this paper. It is assumed that the water and inhibitor are in the liquid-dispersion state and move together with the medium. The inhibitor allows the disruption of exothermic reactions, while being partially consumed. The results of numerical simulations have shown that the presence of an inhibitor makes it possible to reduce the required mass of the extinguishing composition for the successful suppression of a forest fire. It is shown that these results are in good agreement with known experimental data on the efficiency of replacing pure water with an inhibitor solution. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of 10 years of research on models of the megathrust earthquake cycles and crustal deformation associated with the 2011 Tohoku-oki earthquake. Several earthquake cycle models have been proposed for the northeast Japan subduction zone to elucidate why megathrust earthquakes occur at intervals of approximately 600 years and why large slips occurred in the shallow subduction zone. A model that considers a strong asperity in the shallow plate interface, and a hierarchical asperity model that considers the scale dependence of the critical displacement of the rate- and state-dependent friction law have been proposed. Modeling with dynamic weakening of faults has also been proposed. In the model using the shallow friction characteristics obtained by the Japan Trench Fast Drilling Project, rupture from depth can propagate to the trench, resulting in shallow large slips. Submarine crustal deformation has been observed for the first time in addition to dense observations of the inland crustal deformation. The observation of the seafloor deformation near the trench showed that viscoelastic relaxation played an important role in short-term postseismic deformation near the trench. The effects of the low-viscosity region at the oceanic lithosphere and asthenosphere boundary, and the cold forearc mantle wedge (cold nose) have been discussed. Simulations using the nonlinear flow law of rock in the mantle, where a power–law relationship holds between stress and strain rate, and the fault friction law at the plate boundary, show that the Tohoku-oki earthquake caused large stress fluctuations, resulting in a sudden viscosity decrease and rapid flow in the asthenosphere below the oceanic lithosphere. The simulations of the crustal deformation associated with the Tohoku-oki earthquake cycle also indicate that in the later stage of the earthquake cycle, the Pacific coastal region begins to subside due to the increasing slip deficit rate on the deeper parts of the plate interface. These results explain the subsidence of the Pacific coast of northeast Japan observed for about 100 years prior to the Tohoku-oki earthquake. In the future, a model that explains the long-term crust and mantle deformation during the entire Tohoku-oki earthquake cycle must be constructed. [ABSTRACT FROM AUTHOR]

A trend in the development of geophysics is to seek wave theory closer to the physical reality and derive corresponding wave equations to achieve highly accurate forward modeling, imaging, and inversion of complex structures. The generalized continuum mechanics (GCM) theory enriches the context of the conventional continuum mechanics theory by introducing the additional characteristic length scale parameters to represent the microstructural properties of the medium, and the asymmetric elastic wave equations derived from GCM theory can handle the influence of heterogeneity of a medium caused by the microstructural interactions on the propagation of seismic waves. To date, there are few studies on the numerical and analytical solutions of the elastic wave equations derived from the GCM theory, especially in the frequency band of seismic exploration. In addition, there are few studies in the existing literature that incorporate multiple theories and methods of the GCM theory into an integrated frame. In this paper, we introduce the concept of the multi-scale microstructural interactions and construct the quantitative relationship between the characteristic length scale parameter of the medium and the characteristic length scale parameter of the micro-pore reflecting the micro-pore structures, and then integrate the modified couple stress theory and the one-parameter second strain gradient theory into a unified framework for numerical modeling and analysis. [ABSTRACT FROM AUTHOR]

Hydraulic conductivity is one of the most challenging hydrogeological properties to appropriately measure due to its dependence on the measurement scale and the influence of heterogeneity. This paper presents a comparison of saturated hydraulic conductivities (K) determined for a quasi-homogeneous coastal sand aquifer, estimated using eight different methodologies, encompassing empirical, hydraulic and numerical modeling methods. The geometric means of K, determined using 22 methods, spanning measurement scales varying between 0.01 and 100 m, ranged between 3.6 and 58.3 m/d. K estimates from Cone Penetration Test (CPT) data proved wider than those obtained using the other methods, while various empirical equations, commonly used to estimate K from grain-size analysis and Tide-Aquifer interaction techniques revealed variations of up to one order of magnitude. Single-well tracer dilution tests provided an alternative for making preliminary estimates of K when hydraulic gradients were known. Estimates from the slug tests proved between 1.2 and 1.6 times larger than those determined from pumping tests which, with one of the smallest ranges of variation, provided a representative average K of the aquifer as revealed by numerical modeling. By contrast, variations in K with depth could be detected at small scales (~ 0.1 m). Hydraulic Profiling Tool (HPT) system data indicated that K decreases with depth, which was supported by the numerical model results. No scale effect on K was apparent when considering the ensemble of results, suggesting that hydraulic conductivity estimates do not depend on the scale of measurement in the absence of significant aquifer heterogeneities. [ABSTRACT FROM AUTHOR]

Mining backfill is increasingly used in underground mine stopes around the world. A good understanding of the stress distribution in backfilled stopes is a critical concern for the design of barricades, sill mats and side-exposed backfills. In this regard, several published numerical studies reported that the vertical stress versus depth curve can exhibit an increased pace with depth near stope bottom. This phenomenon, known as kink effect, can significantly affect the stress estimation for the design of barricades and base-exposed backfill. In addition, the mechanism of kink effect has never been fully investigated, nor considered in analytical solutions developed for evaluating the stresses in backfilled stopes. In this paper, the mechanism of kink effect is first analyzed and then taken into account in an analytical solution. It is found that the occurrence of kink effect mainly depends on yield or unyield state of backfill, which is in turn determined by the Poisson's ratio μ and internal friction angle φ of the backfill. A conceptual analytical solution is then proposed to evaluate the stress distribution in 2D backfilled stopes by considering the kink effect near the bottom. The proposed solution was first calibrated by a few numerical simulations performed with FLAC2D. The results showed that kink effect takes place, starting from the bottom of stope along a height equaling to 10th and 20th of the backfill's total thickness for the vertical and horizontal stresses, respectively. The calibrated analytical solution was further validated by additional numerical simulations with different backfill properties. [ABSTRACT FROM AUTHOR]

Rock salt has a self-sealing capacity, low permeability, and high thermal conductivity, making it a potential host for heat-generating nuclear waste. The feasibility of nuclear waste disposal within salt formations has been investigated mostly for small-sized canisters. Geologic disposal of larger-sized canisters originally designed for spent fuel storage and transportation has lately been examined as a cost-effective alternative. This raises questions about their long-term vertical movement due to their weight and high decay heat. Low-stress creep governs this movement; however, most salt constitutive models do not incorporate it. In this paper, the Norton and the WIPP creep models are compared with the Lux/Wolters/Lerche (LWL) model and a simpler model that combines linear and Norton creep laws (named combined creep model). The LWL and combined creep models consider pressure solution creep, though all incorporate dislocation creep. The models are first applied to creep tests under various stress levels. The LWL and the combined creep models results fit the experimental data well in both high and low stress ranges, whereas the Norton and WIPP models results only fit in higher-stress ranges. The different models are further applied for analyzing long-term canister movement. A sinking rate of - 4.4 × 10 - 7 mm/year was predicted using the Norton and WIPP models versus - 2.1 × 10 - 2 mm/year and - 3.1 × 10 - 2 mm/year using the LWL and the combined creep models, respectively. This comparative study confirms that creep models calibrated exclusively against high-deviatoric stress data might result in an inaccurate estimation of waste packages sinking rate in salt formations. [ABSTRACT FROM AUTHOR]

The machining of Nomex honeycomb structures represents a technical and scientific barrier for aeronautical applications. The difficulties encountered during the machining of this type of material are linked to the low density of Nomex paper, and to the low thickness of the walls forming the honeycomb cells of this type of structure. In this work, a finite element calculation code "ABAQUS'- EXPLICIT" was used to optimize and analyze the machining by milling of Nomex honeycomb structures. The main objective of this work is to study the influence of the machining conditions on the cutting forces, and the morphology of the chips. [ABSTRACT FROM AUTHOR]

This paper presents the design and 3D numerical modeling of the temporary support system for the twin tunnels in the transition zone of the Esfahan subway project. Ground movements caused by tunneling beneath urban areas can have a significant impact on adjacent structures and therefore require consideration when choosing the excavation method and the type of support system. Due to the old buildings in the historical city of Esfahan, this research requires parametric studies for the use of simulation techniques. This paper focuses on 3D stability analysis and design of the support system required to control the critical strain and ground movement due to excavation of the transition area of the twin tunnels in the Esfahan subway project. A numerical model is developed to estimate the excavation effects on the critical strain and ground settlement and also the effect of reinforcement measures. In the 3D numerical model, a constitutive law characterized by the time-dependent stiffness and strength of the shotcrete is employed. Results show that the suggested support is sufficient to control the settlement and critical strain due to tunneling. Comparison between the 2D model prediction and the results of corresponding 3D model indicates that the conformity between 2D and 3D analysis results decreases in the transition region. One of the most useful methods to determine the induced seismic loads, the use of time-history dynamic analysis is usually done for major projects. In this paper, for the twin tunnels of subway, Fast Lagrangian Analysis of Continua (FLAC) software is used for this purpose. [ABSTRACT FROM AUTHOR]

Landslides involving sensitive clays are recurrent events in the world's northern regions and are especially notorious in eastern Canada. The two critical factors that separate sensitive clay landslides from traditional slope stability analysis are the highly brittle behavior in undrained conditions (strain-softening) characteristic of progressive or retrogressive failures and the large deformations associated with them. Conventional limit equilibrium analysis has numerous shortcomings in incorporating these characteristics when assessing landslides in sensitive clays. This paper presents an extensive literature review of the failure mechanics characteristics of landslides in sensitive clays and the existing constitutive models and numerical tools to analyze such slopes' stability and post-failure behavior. The advantages and shortcomings of the different techniques to incorporate strain-softening and large deformation in the numerical modeling of sensitive clay landslides are assessed. The literature review depicts that elastoviscoplastic soil models with non-linear strain-softening laws and rate effects represent the material behavior of sensitive clays. Though several numerical models have been proposed to analyze post-failure runouts, the amount of work performed in line with sensitive clay landslides is very scarce. That creates an urgent need to apply and further develop advanced numerical tools for better understanding and predicting these catastrophic events. [ABSTRACT FROM AUTHOR]

Surface mining methods have been adopted to extract the coal which is in the form of pillars and roof in old underground coal workings. There are slope failures associated with the extraction method. Conventional slope monitoring systems are available but require physical presence of the person at the site and the readout units which are physically connected to the base units and generally such monitoring is done only during day light. Radar-based systems are being used to monitor the broad area through rain, dust, smoke and operate during both day and night. They provide accurate results, but they are high-cost and require a skilled person for operating in the field. Hence, an investigation taken up to assess the stability of the slope stability over old underground coal workings by using wireless sensor networks (WSNs) and internet of things (IoT). In this paper, monitoring of slope stability using a low cost wireless sensor networks is discussed. An integrated wireless data acquisition system is developed to assess the slope stability and it is validated with conventional instrument and numerical modeling approach. The variation in between integrated slope monitoring system (ISMS) to data logger and numerical modeling is around 3.03%–19%. Statistical analysis results revealed that there is a good correlation between field observations and modeling studies. [ABSTRACT FROM AUTHOR]

In this paper, we present the results of direct numerical modeling of the process of susceptibility of a supersonic boundary layer over an unswept wing with a thin parabolic profile to acoustic noise of various intensities. It was demonstrated that acoustic noise can cause a laminar–turbulent transition over the unswept wing of a supersonic passenger aircraft. [ABSTRACT FROM AUTHOR]

In this paper, hollow glass microspheres (HGMs) are used as fillers to improve the thermal properties of polyester resin. The thermal conductivity coefficient is obtained from experiment and numerical simulations and their results are compared. The thermal conductivity coefficient is measured using KD2 Pro which shows that the thermal conductivity coefficient decreases as the HGM weight fraction increases. For numerical simulations, the HGM sizes are obtained for different weight fractions based on the SEM images, Image J software and the histogram diagram. The RVEs are produced in Digimat and exported into COMSOL Code where the heat transfer problem is solved and the thermal conductivity coefficient is calculated. The HGM size and distribution show no practical effect on the conductivity coefficient. The results of temperature dependent and independent heat capacities and thermal conductivity coefficient are compared which show that the thermal conductivity coefficient using the constant specific heat capacity and thermal conductivity coefficient of matrix shows a better agreement with the experiment. Using the Cooperative rearranging region (CRR) estimate, the interphase width is calculated and added to the model which results show no difference with those without the interphase since its width is much smaller than the HGM size. [ABSTRACT FROM AUTHOR]

The mantle plume model, as an integral part of the Earth's internal convection system, is complementary to the theory of plate tectonics. They together constitute the key configuration of material circulation and energy transport in the Earth's interior. Seismology, high-temperature and high-pressure mineralogy, geology, and geodynamic numerical modeling have conducted comprehensive studies on the mantle plume model since it was proposed. In particular, numerical simulation, which investigates the dynamic processes of mantle plumes by establishing a theoretical model, provides a quantitative description of possible mantle plume evolution and the responses of the Earth's interior and surface, which can be used to explain observations and experimental results from other disciplines. Thus, it is one of the most important means to study plume dynamics. This paper summarizes the research progress in numerical modeling of mantle plumes in past decades, including the origin of mantle plumes, seismological evidence for the existence of plumes, interactions between mantle plumes and the lithosphere, mid-ocean ridges, subduction zones, and the mantle transition zone, as well as the relationship between plumes and large low shear wave velocity provinces. The theoretical results of numerical modeling combined with observations from other disciplines enable us to deeply understand the dynamic process of mantle plumes. With the continuing development of numerical methodology and the improvement of high-performance computing, geodynamic numerical modeling will become a more accurate and efficient approach for studying mantle plume dynamics and related frontier problems in geosciences. [ABSTRACT FROM AUTHOR]

The paper presents one construction of a Godunov-type method based on the separation of operators describing the work of pressure forces and advective transfer. Separate consideration of advective transfer permits describing the motion of both gas and dust components within the framework of a single numerical scheme. In the case of describing gas dynamics, the work of pressure forces is taken into account at a separate stage, independently of transfer. This permits using the numerical scheme in solving star formation problems, where it is necessary to jointly solve the equations of hydrodynamics and dust motion equations. A piecewise parabolic representation of physical variables in all directions is used to reduce the dissipation of the numerical method. The numerical method has been verified on Riemann problems for a hydrodynamic and dust discontinuity, the Sedov problem of point explosion, and the problem of dust cloud collapse, which have an analytical solution. [ABSTRACT FROM AUTHOR]

This paper focuses on an experimental procedure to localize multiple leaks in a nonhomogenous hydraulic pipeline system made up of three portions of two different materials. Then, an experimental setup originally designed for water hammer study was modified and adapted for leak detection using transients. Two leaks were made in some particular locations in the main pipe and a transient event through a rapid closure of a downstream valve was created. To mimic common practical issues that may be encountered, three main leakage cases were considered; a single leak, two simultaneous leaks and two successive leaks (i.e., one leak that appears followed by an abrupt appearance of a second leak after a period of time). Leaks were experimentally localized by analyzing obtained pressure signals in the excitation point. Results were validated through comparison with numerical ones obtained using the method of characteristics. Additionally, a novel formula to localize the second leak in a successive leaks scenario was presented and its accuracy was confirmed for our test case. Experimental techniques presented in this paper and performed on a test bench at lab scale can be extended and tested on large scale hydraulic pipeline systems. [ABSTRACT FROM AUTHOR]