Search Results (20)

Accurate identification of concealed coal seam structures, such as folds or faults, is crucial for safe and effective production in the coal mining industry. In-seam seismic exploration serves as a promising technique for advanced detection of coal seam structures, but traditional numerical simulation methods easily produce errors when coping with irregular interfaces. This study uses the curvilinear grid finite-difference method (FDM) for modeling the 3D channel wave propagation. The body-fitted grids are utilized to conform to undulating interfaces, while the DRP/opt MacCormack difference scheme and the fourth-order Runge–Kutta algorithm are applied for the spatial and temporal derivative approximation, in that order. The forward and backward extrapolation for in-seam waves are implemented in the curvilinear coordinates. The roofs and floors of coal seams and special structures are imaged by reverse-time migration (RTM) using an excitation amplitude imaging condition. Numerical results show that compared with conventional methods, the curvilinear grid method effectively reduces spurious scattering caused by the staircase approximation, improves the modeling accuracy of channel waves, and enhances the continuity and interpretability of imaged coal-seam interfaces and structural boundaries. The proposed method has the potential to enhance the accuracy of channel wave exploration under complex geological conditions, supporting advanced hazard detection in coal mines. Full article

Vaporous cavitating flow may occur in pipelines when a water hammer causes pressure to drop to saturated vapor pressure. This paper presents a two-phase homogeneous flow model for transient vaporous cavitating flows. The homogeneous flow model consists of continuity and momentum balance equations and an equation describing the volume fraction of vapor. A two-step finite difference MacCormack scheme is used to solve the model. The calculated results obtained from the model are compared with those of the classical discrete gas cavity model (DGCM) and with experimental data from the literature. For all test cases, the model converged at a similar number of grids. The numerical results indicate that the model can reproduce cavitation events well, especially for the prediction of the first maximum pressure peak after cavity collapse. The model also provides direct access to the vapor volume fraction at each location as a function of time. Through numerical analyses, the initial vapor volume fraction in the model is selected as 10⁻⁷; with this selection, the numerical results are in good agreement with experimental data. The model also exhibits comparable predictive capability with respect to the DGCM and superior performance under some operating conditions. Nevertheless, neither of these two models can appropriately estimate the pressure phase in severe cavitation events. Full article

The initial part of this study fills a notable research gap by investigating the substantial impact of numerical diffusion errors from different schemes on sloshing tank models. Multiple numerical models were developed: first- and higher-order upwind schemes equipped with precise wall treatment using ghost nodes, MacCormack and central methods that are explicit second-order finite difference methods, and Preissmann and staggered methods employed in full-implicit and semi-implicit modes. Furthermore, the separation of variables technique was proposed for simulating sloshing tanks and deriving an analytical equation for the tank’s natural period. An analytical solution to the perturbation was employed to examine the numerical diffusion of the schemes. Subsequently, two sloshing tests, resonant and near-resonant excitations, were employed to determine the numerical diffusion and calibrate the physical diffusion coefficients, respectively. Finally, an efficient and accurate numerical scheme was applied to a linear shallow water model including physical diffusion and coupled with a single degree of freedom (SDOF), to simulate tuned liquid dampers (TLDs). It shows that the efficiency of TLD is associated with a compact domain around resonance excitation. Contrary to SDOF alone, when SDOF interacts with TLD the impact of structural damping on reducing the response is minimal in resonance excitation. Full article

The water hammer phenomenon, characterized by transient pressure surges due to rapid fluid deceleration in pipelines, poses significant risks to hydraulic systems. Valve closure time is a critical parameter influencing pressure magnitude, necessitating precise calibration to ensure system safety. While numerical methods like the MacCormack scheme provide accurate solutions, their computational intensity limits practical applications. This study addresses this limitation by proposing a machine learning (ML) framework employing a multilayer perceptron (MLP) artificial neural network (ANN) to predict optimal pressure values—defined as the lowest maximum pressure obtained for several closure laws at a given closure time—corresponding to specific valve closure times. The ANN was trained on 637 simulations generated via the MacCormack method, which solves the hyperbolic partial differential equations governing transient flow in a reservoir-pipeline-valve (RPV) system. Performance evaluation metrics demonstrate the ANN’s exceptional robustness and accuracy, achieving a root mean square error (RMSE) of 0.068, Nash-Sutcliffe efficiency (NSE) of 0.99, and a correlation coefficient (R) of 0.99, with a maximum relative error below 1%. The results highlight the ANN’s superior predictive accuracy and flexibility in capturing complex transient flow dynamics, outperforming conventional numerical methods. Notably, the ANN reduced computational time from days for iterative simulations to mere seconds, enabling rapid prediction of pressure-time curves critical for real-time decision-making. This framework offers a computationally efficient and reliable alternative for optimizing valve closure strategies, mitigating water hammer risks, and enhancing pipeline safety. By bridging numerical rigor with machine learning, this work enhances hydraulic infrastructure resilience across industrial and urban networks. Full article

Background: Children generally face a higher incidence of airway management complications, intubation difficulties, and the risk of failed intubation. Currently, there is sufficient evidence in clinical practice for the use of videolaryngoscopes in pediatric airway management. However, there are a number of standard-blade videolaryngoscopes available for children. In addition, there is no clear recommendation on which videolaryngoscope is superior. The primary objective of this study is to compare the first pass success rate and the Percentage of Glottic Opening (POGO) scores with Cormack–Lehane (CML) scores obtained through direct and indirect laryngoscopy with HugeMed and McGrath Mac videolaryngoscopes in pediatric patients with an unanticipated, difficult airway. Materials and Methods: Following the Ethics Committee approval and written parental consents, a total of 40 elective surgical patients, aged 3 and under, with ASA 1–3 risk classification, and undergoing general anesthesia, were included in the study. After induction of general anesthesia, the first group of patients (Group McGrath, n = 20) was intubated with the McGrath Mac videolaryngoscope, and the second group (Group HugeMed, n = 20) with the HugeMed videolaryngoscope. Before intubation, CML and POGO scores were recorded for both groups using direct and indirect laryngoscopy with videolaryngoscopes. Intubation time, number of attempts, need for cricoid pressure, optimization maneuver requirement, and hemodynamic parameters were recorded for both groups. Results: There was no significant difference between groups in demographic data including age, gender, body mass index, ASA, and hemodynamic parameters. A significant improvement was observed in CML and POGO scores using indirect laryngoscopy (p < 0.001). CML scores obtained with the McGrath Mac were significantly lower than the HugeMed Group (p = 0.0034). The mean POGO value calculated with indirect laryngoscopy was significantly higher in the McGrath Group compared to the HugeMed Group (92.63 ± 6.09 vs. 88.75 ± 4.44, respectively). Conclusions: Videolaryngoscopes improved laryngeal visualization in children under 3 years old. Compared to HugeMed, in indirect laryngoscopy, the McGrath Mac videolaryngoscope was found to be superior, with better CML and POGO scores. However, number of tracheal intubation attempts, success rate, complication risk, and hemodynamic parameters did not show any significant difference between the groups. Clinical trial registration number was NCT06484517. Full article

Adopting an appropriate method to analyze the spatial evolution process of tailings flow after tailings dam failure can provide a rational assessment of the inundation range and evaluate the subsequent disaster. Simultaneously, it can offer a foundation for tailings pond construction and safety management. This paper, focusing on a specific iron mine in Xiagao, Guangdong, establishes a three-dimensional simulation of the tailings pond based on the design drawings of the raised tailings pond. Utilizing the depth integral method as the theoretical basis, this research references parameter values obtained through model experiments for numerical simulation. Through the numerical simulation method, the study simulates the disaster range, flow, and spatial state of the tailings flow after a dam break. The tailings flow velocity and the depth of the flow in the affected areas are derived, demonstrating the disasters resulting from dam failure. Moreover, the feasibility of raising the tailings dam is evaluated. The assessment extends to the damage risk of tailings dam failure to critical downstream facilities and provides disaster prevention and control suggestions for high-risk situations. This study ultimately offers technical support for the prevention and control of tailings dam failure accidents and the advancement of mine safety production. Full article

Copper is an essential trace metal for biological processes in humans and animals. A low level of copper detection at physiological pH using fluorescent probes is very important for in vitro applications, such as the detection of copper in water or urine, and in vivo applications, such as tracking the dynamic copper concentrations inside cells. Copper homeostasis is disrupted in neurological diseases like Alzheimer’s disease, and copper forms aggregates with amyloid beta (Ab42) peptide, resulting in senile plaques in Alzheimer’s brains. Therefore, a selective copper detector probe that can detect amyloid beta peptide-copper aggregates and decrease the aggregate size has potential uses in medicine. We have developed a series of Cu²⁺-selective low fluorescent to high fluorescent tri and tetradentate dentate ligands and conjugated them with a peptide ligand to amyloid-beta binding peptide to increase the solubility of the compounds and make the resultant compounds bind to Cu²⁺–amyloid aggregates. The copper selective compounds were developed using chemical scaffolds known to have high affinity and selectivity for Cu²⁺, and their conjugates with peptides were tested for affinity and selectivity towards Cu²⁺. The test results were used to inform further improvement of the next compound. The final Cu²⁺ chelator–peptide conjugate we developed showed high selectivity for Cu²⁺ and high fluorescence properties. The compound bound 1:1 to Cu²⁺ ion, as determined from its Job’s plot. Fluorescence of the ligand could be detected at nanomolar concentrations. The effect of this ligand on controlling Cu²⁺–Ab42 aggregation was studied using fluorescence assays and microscopy. It was found that the Cu²⁺–chelator–peptide conjugate efficiently reduced aggregate size and, therefore, acted as an inhibitor of Ab42-Cu²⁺ aggregation. Since high micromolar concentrations of Cu²⁺ are present in senile plaques, and Cu²⁺ accelerates the formation of toxic soluble aggregates of Ab42, which are precursors of insoluble plaques, the developed hybrid molecule can potentially serve as a therapeutic for Alzheimer’s disease. Full article

Background and Objective: Placing the laryngoscope blade directly under the epiglottis (known as the direct view (DV) method) during videolaryngoscopy offers a superior view of the glottis when compared to the indirect method of lifting the epiglottis by positioning the Macintosh blade tip over the vallecula. While there are few studies comparing glottic views using Miller and Macintosh blades in pediatric patients, we have not come across such a study in adults. In this study, we aimed to compare the effectiveness and hemodynamic responses of the Miller laryngoscope and the McGrath-MAC videolaryngoscope (VL) in visualizing the glottic opening using the DV method. Material and Methods: A prospective study was conducted between August and December 2022 at XXX Hospital on 85 patients scheduled for surgical procedures involving endotracheal intubation. Patients were divided into two groups: Miller laryngoscope (Group M) and McGrath-MAC videolaryngoscope (Group VL) and intubated using the direct lifting method of the epiglottis. Hemodynamic responses before and after induction, as well as during laryngoscopy, intubation time, number of attempts, Cormack and Lehane (C&L) score, percentage of glottic opening (POGO), duration of the view of the opening, and need for external laryngeal pressure during intubation were recorded. Results: Both laryngoscopes showed similar effectiveness in terms of POGO and C&L score when used with the direct lifting method of the epiglottis. The median POGO values according to the DV method were 80% in Group M and 70% in Group VL (p = 0.099). Hemodynamic responses, intubation time, number of attempts, duration of view of the glottis opening, and the need for external laryngeal pressure were similar between the groups. Conclusions: Due to its ability to provide effective intubation conditions, we believe that the McGrath-MAC VL, when used with the indirect view method, can also be utilized in anesthesia practices alongside the DV method. Full article

In this work, a predictor–corrector compact difference scheme for a nonlinear fractional differential equation is presented. The MacCormack method is provided to deal with nonlinear terms, the Riemann–Liouville (R-L) fractional integral term is treated by means of the second-order convolution quadrature formula, and the Caputo derivative term is discretized by the L1 discrete formula. Through the first and second derivatives of the matrix under the compact difference, we improve the precision of this scheme. Then, the existence and uniqueness are proved, and the numerical experiments are presented. Full article

A new approach to the numerical study of arbitrary waveform impulses in a layered porous and fractured-porous medium in a two-dimensional formulation has been developed. Layers can have different characteristics and contain fractures. A computer implementation of the mathematical model based on the finite-difference MacCormack method has been completed. A number of test calculations have been carried out confirming the reliability of the numerical solutions obtained. The possibility of using the proposed approach to solve problems of wave dynamics is shown. Full article

This study aimed to compare the intubation effectiveness of the bébé Vie Scope™ (VieScope) and direct laryngoscopy for emergency intubation in a pediatric manikin model performed by paramedics with and without personal protective equipment for aerosol generating procedures (PPE-AGP). Participants performed endotracheal intubation using VieScope and standard Macintosh laryngoscope (MAC) in two research scenarios: (1) without PPE-AGP, and (2) with PPE-AGP. Fifty-one paramedics without any previous experience with the VieScope participated in this study. In the PPE-AGP scenario, in the VieScope group, the percentage of successful tracheal intubation on the first attempt was higher compared to the MAC group (94.1 vs. 78.4%, p = 0.031), intubation time was shorter (29.8 vs. 33.9 s, p < 0.001), and percentage of glottic opening (POGO) score was higher 91.0 vs 77.8 (p < 0.001). On the Cormack–Lehane scale, intubation with VieScope intubation was associated with higher scores rated at 1 (64.7 vs. 29.4%) than in the MAC group (p = 0.001). For intubation in the non-PPE scenario, there were no statistically significant differences between VieScope and MAC in relation to above parameters. Summarize, the bébé VieScope™ under PPE-AGP wearing conditions has proven to be a useful device for airway management in children providing better visualization of the larynx, better intubation conditions, and a higher success rate of tracheal intubation on the first attempt and reduced intubation time compared to the standard Macintosh laryngoscope. Full article

Pulse hydraulic fracturing (PHF) is a key technique for reservoir stimulation. PHF can well accelerate the rupture of rock. However, the supercharging mechanism of PHF is not fully understood. The main reason is that the pressure distribution and its variation, especially the peak pressure characteristics, are unclear inside the pipe and fissure. The present research focuses on the sine pulse applied at the inlet of a pipe or fracture to reveal the variation regularity of peak pressure with the pulse frequency, amplitude, pipe length, diameter and wave speed. First, the weakly compressible Navier–Stokes equations were developed to simulate the variation of fluid pressure. The computation codes were developed using the MacCormack method validated by the existing experimental data. Then, the sine pulse effect was studied inside the pipe and fissure. Last, a new frequency model was built to describe the relationship between the optimal pulse frequency, wave speed and pipe length. The results show that there is a family of frequencies at which the peak pressure of the endpoint can be significantly enhanced and that these frequencies are the optimal pulse frequency. It is found that the optimal pulse frequency depends on the pipe or fissure length and wave speed. At the optimal pulse frequency, the peak pressure at the endpoint can be increased by 100% or more, and the cavitation phenomenon occurs. However, the peak pressure decreases when with the decrease in the pipe diameter and fissure departure due to the friction drag effect of the wall. These new landmark findings are very important for the PHF technique. In addition, a new universal frequency model is built to predict the optimal sine pulse frequency. The present research shows the variation regularity of the fluid pressure inside the pipe and develops a sine frequency-controlled method, providing a potential guide for reservoir stimulation. Full article

An accurate second-order spatial and temporal finite-difference scheme is applied to solve the dynamics model of a depth-averaged avalanche. Within the framework of the MacCormack scheme, a total variation diminishing term supplements the corrector step to suppress large oscillations in domains with steep gradients. The greatest strength of the scheme lies in its high computational efficiency while maintaining satisfactory accuracy. The performance of the scheme is tested on a granular flume flow–obstacle interaction scenario and a granular dam breaking scenario. In the former, the flume flow splits into two granular streams when an obstacle is encountered. The opening between the two granular streams widens when the side length of the obstacle increases. In the simulation, shock waves with a fan-shaped configuration are captured, and successive waves in the tail of the avalanche between the two streams are observed. In the latter scenario, the average values and the fluctuations in the flow rate and velocity (at relatively steady state) decrease with the width of the breach. The capture of complex and typical granular-flow phenomena indicates the applicability and effectiveness of combining the TVD-MacCormack Scheme and S-H model to simulate dam breaking and inclined flow–obstacle interaction cases. In this study, the dense granular flow strikes on a rigid obstacle that is described by a wall boundary, rather than a topographic feature with a finite slope. This shows that the TVD-MacCormack scheme has a shock-capturing ability. The results of granular dam break simulations also revealed that the boundary conditions (open or closed) affect the collapse of the granular pile, i.e., the grains evenly breached out under closed boundary conditions, whereas the granules breaching out of the opening were mostly grains adjacent to the boundaries under open boundary conditions. Full article

Carbon footprint reduction issues have been drawing more and more attention these days. Reducing the energy consumption is among the basic directions along this line. In the paper, a low-energy approach to tsunami danger evaluation is concerned. After several disaster tsunamis of the XXIst century, the question arises whether is it possible to evaluate in a couple of minutes the tsunami wave parameters, expected at the particular geo location. The point is that it takes around 20 min for the wave to approach the nearest coast after a seismic event offshore of Japan. Currently, the main tool for studying tsunamis is computer modeling. In particular, the expected tsunami height near the coastline, when a major underwater earthquake is detected, can be estimated by a series of numerical experiments of various scenarios of generation and the following wave propagation. Reducing the calculation time of such scenarios and the necessary energy consumption for this is the scope of this study. Moreover, in case of the major earthquake, the electric power shutdown is possible (e.g., the accident at the Fukushima nuclear power station in Japan on 11 May 2011), so the solution should be of low energy-consuming, preferably based at regular personal computers (PCs) or laptops. The way to achieve the requested performance of numerical modeling at the PC platform is a combination of efficient algorithms and their hardware acceleration. Following this strategy, a solution for the fast numerical simulation of tsunami wave propagation has been proposed. Most of tsunami researchers use the shallow-water approximation to simulate tsunami wave propagation at deep water areas. For software implementation, the MacCormack finite-difference scheme has been chosen, as it is suitable for pipelining. For hardware code acceleration, a special processor, that is, the calculator, has been designed at a field-programmable gate array (FPGA) platform. This combination was tested in terms of precision by comparison with the reference code and with the exact solutions (known for some special cases of the bottom profile). The achieved performance made it possible to calculate the wave propagation over a 1000 × 500 km water area in 1 min (the mesh size was compared to 250 m). It was nearly 300 times faster compared to that of a regular PC and 10 times faster compared to the use of a central processing unit (CPU). This result, being implemented into tsunami warning systems, will make it possible to reduce human casualties and economy losses for the so-called near-field tsunamis. The presented paper discussed the new aspect of such implementation, namely low energy consumption. The corresponding measurements for three platforms (PC and two types of FPGA) have been performed, and a comparison of the obtained results of energy consumption was given. As the numerical simulation of numerous tsunami propagation scenarios from different sources are needed for the purpose of coastal tsunami zoning, the integrated amount of the saving energy is expected to be really valuable. For the time being, tsunami researchers have not used the FPGA-based acceleration of computer code execution. Perhaps, the energy-saving aspect is able to promote the use of FPGAs in tsunami researches. The approach to designing special FPGA-based processors for the fast solution of various engineering problems using a PC could be extended to other areas, such as bioinformatics (motif search in DNA sequences and other algorithms of genome analysis and molecular dynamics) and seismic data processing (three-dimensional (3D) wave package decomposition, data compression, noise suppression, etc.). Full article

Events of a seismic nature followed by catastrophic floods caused by tsunami waves (the incidence of which has increased in recent decades) have an important impact on the populations of littoral regions. On the coast of Japan and Kamchatka, it takes nearly 20 min for tsunami waves to approach the nearest dry land after an offshore seismic event. This paper addresses an important question of fast simulation of tsunami wave propagation by mapping the algorithms in use in field-programmable gate arrays (FPGAs) with the help of high-level synthesis (HLS). Wave propagation is described by the shallow water system, and for numerical treatment the MacCormack scheme is used. The MacCormack algorithm is a direct difference scheme at a three-point stencil of a “cross” type; it happens to be appropriate for FPGA-based parallel implementation. A specialized calculator was designed. The developed software was tested for precision and performance. Numerical tests computing wave fronts show very good agreement with the available exact solutions (for two particular cases of the sea bed topography) and with the reference code. As the result, it takes just 17.06 s to simulate 1600 s (3200 time steps) of the wave propagation using a 3000 × 3200 computation grid with a VC709 board. The step length of the computational grid was chosen to display the simulation results in sufficient detail along the coastline. At the same time, the size of data arrays should provide their free placement in the memory of FPGA chips. The rather high performance achieved shows that tsunami danger could be correctly evaluated in a few minutes after seismic events. Full article