Source Parameters Research Articles

Effect of slip velocity on Newtonian fluid flow induced by a stretching surface within a porous medium

This article aims to examine an unsteady 2-D laminar flow of magnetohydrodynamic fluid caused by an elastic surface immersed in a permeable medium under the influence of thermal radiation and extended heat flux. Thermal conductivity and viscosity both are supposed to vary with temperature. This flow model also includes velocity slip, heat source, and joule heating. The governing equations of the fluid, including momentum and energy equations, of the proposed problem are transfigured into a system of interconnected non-linear ordinary differential equations through similarity transformations. The resultant equations are solved efficiently by employing the shooting technique in combination with the fourth-order Runge-Kutta method. Numerical values and the effect of numerous governing factors on the flow field, temperature distribution, local skin friction coefficient, and Nusselt number are showcased via graphs and tables. The investigation reveals that velocity slip, heat source, and porosity parameters enhance the temperature field while diminishing the velocity field. Furthermore, the velocity slip parameter notably reduces both the coefficient of skin friction and the Nusselt number.

Effects of fault roughness on estimating critical slip-weakening distance from fault slip history: A laboratory study

Earthquakes are the dynamic rupture of faults governed by fault weakening processes. Critical slip-weakening distance (Dc) is a crucial source parameter of earthquakes, and the determination of Dc is of great concern to semiologists. However, determining Dc for natural earthquakes is challenging due to the trade-off in inversed source models. To solve this problem, Fukuyama and his coworkers proposed a simple method (denoted as the F&M method) to estimate Dc directly from slip-velocity functions. According to the F&M method, the fault slip at the peak slip velocity (Dc') can be used as an approximation of Dc. However, the feasibility of this method has not been completely resolved. Here, we performed laboratory earthquake rupture experiments to examine the validity of the F&M method. Experiments were conducted on faults with different roughness and stress level. We studied the effect of fault roughness on the validity of the F&M method. Our results show that the increase in fault roughness could complicate the fault weakening process, producing repeated weakening and strengthening phase, which leads to a prominent deviation between Dc' and Dc. Furthermore, we also observed a correlation between the critical slip-weakening distance Dc and the final fault slip D. Such correlation implies the scale-dependent nature of Dc, which is consistent with seismic observations in the field.

Explosive eruption style modulates volcanic electrification signals

Volcanic lightning detection has proven useful to volcano monitoring by providing information on eruption onset, source parameters, and ash cloud directions. However, little is known about the influence of changing eruptive styles on the generation of charge and electrical discharges inside the eruption column. The 2021 Tajogaite eruption (La Palma, Canary Islands) provided the rare opportunity to monitor variations in electrical activity continuously over several weeks using an electrostatic lightning detector. Here we show that throughout the eruption, silicate particle charging is the main electrification mechanism. Moreover, we find that the type of electrical activity is closely linked to the explosive eruption style. Fluctuations in the electrical discharge rates are likely controlled by variations in the mass eruption rate and/or changes in the eruption style. These findings hold promise for obtaining near real-time information on the dynamic evolution of explosive volcanic activity through electrostatic monitoring in the future.

Research on the classification of complex noise-mixed microseismic events based on machine vision

Event classification is important for accurately monitoring and warning against rockburst hazards using microseismic technology. Here, we propose an automatic classification method for microseismic events based on machine vision. The method uses Histogram of Oriented Gradient (HOG) integrated with Support Vector Machine (SVM) as the core model (HOG-SVM, HSVM) to classify microseismic events. First, the method uses as input spectrograms generated from microseismic event signals recorded in the field. Next, the HOG method is used to accurately extract the spectral feature information of the useful signals of microseismic events under the interference of noisy signal. Finally, the extracted feature data is used to train SVM, after the training is completed, the SVM is used to classify the microseismic events. The performance of the method for categorizing microseismic events was tested using multiple independent test sets built from data monitored in the field of a mine in Shandong Province. The results show that the method can effectively extract the spectral feature information of useful signals of microseismic events contaminated with noise, with good classification accuracy and robustness to noise. It classifies microseismic events with high accuracy and efficiency compared to well-performing classification methods based on seismic source parameters and typical depth models. The method can provide technical support for the effective classification of microseismic events in complex construction sites, especially in noisy deep underground construction environments.

Source Parameters and Seismogenic Fault Model of the 2024 Mw 7.0 Wushi (Xinjiang, China) Earthquake Revealed by InSAR Observations

Source Parameters and Seismogenic Fault Model of the 2024 Mw 7.0 Wushi (Xinjiang, China) Earthquake Revealed by InSAR Observations

Improved of Multiobjective Fuzzy Probabilistic Solid Transportation Models in Transportation Systems

Transportation activities are stages in the product distribution system. The purpose of the transport system is to minimize the total cost. If there is more than one objective function and consider more than one type of vehicle, it is called a multiobjective solid transportation problem. In some cases, the parameter transportation model is under uncertainty. A probabilistic and fuzzy approach can be used. This research introduces a probabilistic fuzzy multiobjective solid transportation model where the source, destination and vehicle parameters follow the Pareto distribution. A triangular fuzzy number expresses the coefficient of the objective function. The obtained model is applied to the problem of the metal crate transportation system. There are two objective functions; the first is the objective function to minimize the total cost. The second is the objective function to minimize the total transportation time. Three types of vehicles are considered: HDL, Engkel and Wingbox. The result is that the total cost is Rp. 3836595, and the total time is 757.245 minutes or 13 hours.

High intensity proton source based on a hollow-cathode reflex discharge.

We describe here the electrode system, design, and parameters of an ion source based on a Penning-type hollow-cathode reflex discharge developed for generation of proton beams. Especially for proton beam generation, a modified geometry of both hollow and reflex cathodes was fabricated. The working gas is molecular hydrogen. Ion extraction and beam formation are performed using a three-electrode single-aperture optical system with a 3-mm diameter emission aperture. At an accelerating voltage of 33-35kV and a discharge current of 0.55A in continuous mode, the ion beam current was 15-17 mA, and in pulsed mode, at a discharge current of about 2A, the beam current was 55 mA. The beam consists mainly of H+, H2+, and H3+ ions, with the proton (H+) fraction up to 27% in continuous mode and 40% in pulsed mode.

Investigation of projectile fragment emission in the fragmentation of 28Si on C target at 736 A MeV

The emission angular distributions, the transverse momentum distributions and the temperature parameters of projectile fragments produced in fragmentation of [Formula: see text]Si on C target at 736[Formula: see text]A[Formula: see text]MeV are measured. It is found that the scattering angle of primary silicon ions is smaller than the emission angle of their fragments. The average value and the width of the angular distribution and the transverse momentum distribution are increased with the decrease of the charge of projectile fragments. The cumulative squared transverse momentum distribution of projectile fragments can be well fitted by a single Rayleigh distribution, which indicates that the projectile fragments are emitted from a single temperature emission source. Most of the temperature parameters of projectile fragments emission source are in the range of 2–5[Formula: see text]MeV, which does not obviously depend on the charge of the projectile fragments.

Integrated geophysical Investigation for gold mineralization potential over southern parts of Kebbi state and its Environs, northwestern Nigeria

The potential zones of gold mineralization were identified in this study using aeromagnetic and aero-radiometric methods. The Nigerian Geological Survey Agency (NGSA) provided half-degree airborne magnetic and radiometric datasets covering the southern part of Kebbi State. Magnetic data were subjected to first vertical derivative (1VD), total gradient amplitude (TGA), total horizontal derivative (THD), source edge detection (SED), center for exploration targeting (CET), Euler deconvolution (ED) and source parameter imaging (SPI) to identify favourable structures to gold mineralization. Aero-radiometric data delineation of the region of hydrothermal alteration zones through the K/eTh ratio, K_deviation, F_parameters, and Ternary image analyses were successful. The results of the magnetic data techniques revealed the regions of major structures/or lineaments with gold mineralization attributes, trending in the NE to SW directions and the SE to NE parts of the study area. The depth to the structures of the magnetic source hosting gold mineralization was less than 5 m using algorithm ED and SPI techniques. Normalized radiometric data showed the area of anomalously high and moderate hydrothermal altered zones. The region's designation as a gold field is supported by major fault lines observed on the 1VD, a sequence of bristle fractures from the CET analysis, and high values of K_deviation and F_parameter, all of which are were visible on the Ternary images. The integrated results revealed zones of major structures and hydrothermal regions of gold fields at Agwara, Western Magama, Rijau, Fakai, Bukkuyum, and Borgu in the SE of the study area.

Avoiding heat source calibration for finite element modeling of the laser powder bed fusion process

The melt pool characteristics govern process stability and microstructure development during Laser Powder Bed Fusion (LBPF). The melt pool is strongly affected by the laser parameters and based on the melt pool depth-to-width ratio, three melting modes can be distinguished: conduction, transition, and keyhole mode. Finite element (FE) simulations have been extensively used to investigate the cyclic thermal history of the LPBF process and the effects of different process parameters on the part quality. However, the heat sources applied in such simulations can only accurately predict the melt pool behavior, and thus the temperature profile, when processing in conduction mode. As for the transition and keyhole regime modeling, heat source parameters or material properties are usually adjusted to make the simulated melt pool dimensions match the real values. This study proposes a novel approach to bypass the conventional heat source calibration strategy to simulate the LBPF process across different melting regimes. The predicted melt pool dimensions are validated for a wide range of process parameters applied to three different alloys: Ti-6Al-4 V, 316 L austenitic stainless steel (316 L), and 2507 super duplex stainless steel (SDSS). The average errors obtained on the melt pool width, depth, length, and aspect ratio are 9.7 %, 12.4 %, 14.5 %, and 14.3 % respectively. These results demonstrate how the proposed approach can capture the melt pool dimensions throughout different materials and melting modes eliminating the time-consuming heat source calibration steps and facilitating the LPBF modeling workflow.

Application of melt pool profiles for parameter calibration of Goldak’s heat source model

Goldak’s ellipsoidal heat source model is widely accepted in laser powder bed fusion (LPBF) process simulations. The model is dependent on three inherent flux distribution parameters and absorptivity which need to be calibrated before application. However, the uniqueness of the calibrated heat source parameters has not been established, which is crucial to accurately represent the energy density distribution in numerical studies. This paper proposed a novel parametric optimization method that can uniquely calibrate these four heat source parameters with high accuracy. Both the simulated cross-sectional (CS) profile and the mid-front (MF) profile of the melt pool were used during calibration. The differences between the experimental and simulated profiles formed the objective function of the parametric optimization problem, which was calculated by using the least power norm method on the deviations between melt pool boundary curves. A genetic algorithm (GA) with elitism selection approach was employed to optimize the heat source parameters by minimizing this single objective function value. To theoretically verify the applicability of the method, two theoretical case studies involving two distinct sets of heat source parameters were carried out. A unique solution of Goldak’s heat source parameters with less than 2 % error can be achieved within 50 generations of the optimization process. A single-track experiment was conducted to demonstrate the application of the proposed method in a real scenario. The CS and MF melt pool profiles were extracted and the calibration procedure was applied. The profiles from simulation with the calibrated heat source parameters exhibited a good agreement with experimental results. The calibrated parameters were used to simulate multi-track printing on a single layer for validation of the proposed method. The CS melt pool profiles obtained from the multi-track simulation and multi-track experiment agreed well, which validated the accuracy of the proposed calibration method and its utility in obtaining the key Goldak heat source parameters for LPBF simulation.

Seismic Hazard Assessment in the Southeastern Korean Peninsula for Large Earthquakes in Northern Kyushu, Japan: A 3D Numerical Simulation of Pseudodynamic Rupture Scenarios

Abstract Active fault segments in the Northern Kyushu area are of concern in seismic hazard analysis of the southeastern Korean Peninsula (KP) due to their proximity. In this study, we numerically simulate the peak ground motions at the southeastern KP for Mw 6.7–7.1 earthquake scenarios at five major active fault segments located in northern Kyushu: Kego SouthEastern, Nishiyama OshimaOki, Nishiyama Nishiyama, Kikugawa Central, and Kikugawa Northern fault segments. We conducted fully 3D seismic-wave propagation simulations integrating 3D seismic velocity model and earthquake scenarios generated through pseudodynamic rupture modeling. After applying the region-specific attenuation value, the predicted peak ground velocities (PGVs) ranged from 0.18 cm/s (modified Mercalli intensity [MMI] III) to 26.76 cm/s (MMI VIII), depending on the earthquake scenarios. The PGV distributions were influenced by several factors, such as crustal velocity anomalies, rupture directivity, and the distribution of source parameters on the fault plane. Despite the fixed fault geometries, magnitudes, and hypocenters, significant variations in peak ground-motion distributions were simulated due to differences in the source statistics. The estimated probability density distributions of PGV indicated a significant likelihood of peak ground motions surpassing 20 cm/s in the Yeongnam Province. Furthermore, we identify a linear relationship between the average PGV values and standard deviation across 20 scenarios for each fault segment, to quantify the uncertainty in the PGV distributions.

PROGRAM AND ANALYTICAL COMPLEX OF THE INDUSTRIAL SAFETY AND HEALTH ANALYSIS SYSTEM

Aim. To investigate the quantitative characteristics of magnetic fields created during electric contact welding by various methods: contact point, arc-contact, capacitor point, contact-contact continuous and pulsating reflow. The problem being solved is the lack of necessary information on the electromagnetic safety of the specified welding methods. Methodology. A description of the proposed methodical approaches to determining the levels of magnetic fields, means of measuring them, and methods of assessing their impact on the welder's body is provided. Based on the analysis and processing of the received oscillograms and spectrograms of magnetic fields, measurements of their quantitative characteristics were performed. To determine the general level of the multifrequency magnetic field that occurs during contact welding, the proposed generalized indicator of the level of the magnetic field was used. Implications of research. It was established that during contact spot welding with a stationary machine, the magnetic field level exceeds the maximum permissible value at the workplace in the range of 50-1000 Hz at a distance of 0.3 m from the welding electrodes. During manual welding by this method, the level of the magnetic field exceeds the permissible level in the frequency ranges of 5-50, 50-1000 Hz directly near the electric cable. Condenser spot welding with direct current is characterized by exceeding the maximum allowable MP at the workplace in the high-frequency range of 1000–10000 Hz. During arc-joint welding at the workplace, exceeding the maximum allowable levels of the magnetic field was not detected. Practical implications. It is shown that the spectral composition and magnitude of the magnetic field signal is determined by the welding method itself and the initial parameters of the power sources. The obtained results can be used in the field of welding production and labor protection for the improvement of contact welding technologies and the development of measures to protect welders from the magnetic field.

Thermal transport characteristics of fluid-particle suspension in a vertical uniform tube: A computational study on Rabinowitsch fluid with uniform heat source

Problem statement The thermal transport of fluid-particle suspension in Rabinowitsch fluid is discussed theoretically in a vertical uniform tube under the consideration of a uniform heat source. Methodology The fluid and particle phase models are used to develop the mathematical model in the form of partial differential equations which are solved through the symbolic software MATHEMATICA version 12.0 and present the exact solution of temperature distribution, velocity of fluid and particle phases, wall shear stress, pressure gradient, pressure rise, and stream function, etc. Computational results and findings The volume fraction density of the particles slows down the motion of the fluid particles. The velocity of Newtonian fluid is maximum as compared to pseudo-plastic and Dilatant fluids. The fluid phase velocity is superior to particle phase velocity distribution for all pertinent parameters of the analysis. The pressure rise increases in the case of Newtonian and pseudo plastic fluid and decreases in Dilatant fluid. The trapping phenomena are strongly associated with the volume fraction density of the particle. The shear stress shows a decreasing trend against the volume fraction density of the particles, Grashoff number, and heat source parameter. Special case The current fluid model (Rabinowitsch fluid) can be reduced in Newtonian, pseudo plastic, and Dilatant fluid for taking κ → 0 , κ < 0 , and κ > 0 , respectively. Applications The current analysis can be useful in biomedical engineering to observe the blood supply through the arteries, the removal of kidney stones, and also the passage of urine to the bladder from the ureter. Originality The present research is original and has not been published before.

Seismic performance of underground subway station structure near the strike-slip fault by the developed hybrid IBE-FEM method

To investigate the influence of strike-slip faults on the seismic responses of underground structures, based on the single-layer potential theory of the boundary element concept and the fault-site-underground structure coupling mechanisms, we proposed a hybrid indirect boundary element-finite element numerical method (IBE-FEM) to simulate efficiently the seismic response of the entire process from the near seismogenic-fault to the underground structure. Initially, based on the kinematic finite-fault model, the seismic wavefield of an overlying soft-soil sedimentary-layer site subjected to strike-slip faults with source parameters, such as rupture velocity, dip-angle, and upper-boundary burial depth, was solved using the indirect boundary element method (IBE). Subsequently, the accuracy of the IBE-FEM in predicting the site seismic wavefield was verified. On this basis, the influence laws of the source parameters and the fault-site coupling effects on the seismic performance of the structure were preliminarily investigated by establishing a numerical model of the nonlinear dynamic interaction system of a soil-underground structure. The results showed that the seismic responses of the underground structure located in the footwall far-fault region were more strongly affected by variations in the rupture velocity. The lateral deformation of the structure under the rupture velocity condition of bedrock shear-wave velocity (vs) was dramatically increased compared to sub-vs, and the lowest amplification is 59 %. Furthermore, the hanging wall and seismic damage concentration effects significantly impacted the structure located in a strike-slip fault site with a shallow-burial. This study provides a reliable and efficient analytical method for the seismic design of underground structures in complex near-fault regions.

Synthesize and characterization of silver coated Ti powders from waste titanium chips by mechanical milling assisted electroless plating method

This study used an electroless silver (Ag) coating method on Ti powders obtained from waste turnings using mechanical milling, a recycling technique. Various parameters of Ag source and reducing agent ratios were utilized in the Ag coating processes. The results demonstrated that increasing the silver source and reducing agent ratios resulted in a more homogeneous and thicker Ag coating layer on Ti powders. The rise in the reduced silver ratio resulted in an increase in crystallite size compared to untreated particles, which was attributed to the reduction of residual dislocations in Ti through the presence of Ag. The amount of silver on silver-coated Ti powders ranged from 12.49 wt% to 24.4 wt%. Furthermore, an increase in the silver ratio significantly enhanced the oxidation resistance properties. The mass change with oxidation obtained from TGA analysis reduced from 26.31 wt% to 14.88 wt% with increasing silver coating layer on Ti powders.

The Effect of Energy Parameters of Power Sources on the Structure and Properties of Permanent Joints at Manual Arc Welding

The study presents the results of the research into the effect of the dynamic properties of inverter and diode power sources of welding arc power supply on the stability of melting and transfer of electrode metal into the weld pool. The principal energy parameters of the power source include the rates of rise and fall of short-circuit current, the ratio of arc burning current to short-circuit current, and other related factors. It has been demonstrated that an increase in the rate of change of these parameters within one welding mode microcycle alters the properties of heat and mass transfer, increases the frequency of electrode metal droplet transfer, reduces the size of transferred droplets in the weld pool and the duration of their stay on the electrode end under the influence of the high temperature of the welding arc, and the duration of short circuits. The increase in the mass fraction of alloying elements at their transition from the coated electrode to the weld metal is demonstrated to depend on the rate of change of the main energy parameters of one welding mode microcycle of the inverter power source in comparison with the diode rectifier. An enhancement in the structural integrity and properties of permanent joints during welding has been observed when using an inverter power source for the welding arc with high dynamic properties.

Computational investigation of methanol-based hybrid nanofluid flow over a stretching cylinder with Cattaneo–Christov heat flux

Abstract This study investigates heat transfer rates in (AA7075-AA7072/Methanol) hybrid nanofluid flows, considering non-uniform heat sources and Cattaneo–Christov heat flux, with significant implications for aerospace engineering by enhancing thermal management in aircraft engines. The findings could revolutionize automotive cooling system efficiency, optimize heat dissipation in electronic devices, and advance the design of renewable energy systems such as concentrated solar power plants. The study aims to conduct a comparative analysis of (AA7075/Methanol) nanofluid and (AA7075-AA7072/Methanol) hybrid nanofluid flow, examining heat transfer rates, non-uniform heat sources, and Cattaneo–Christov heat flux theory around a stretching cylinder. Thermal radiation and the Biot number are also evaluated. Two different nanoparticles, AA7072 and AA7075, are used with methanol to create AA7075/Methanol nanofluid and AA7075-AA7072/Methanol hybrid nanofluid. The study compresses the resultant non-linear partial differential equation system and applies suitable similarity transformations to reduce the governing partial differential equations with boundary conditions to dimensionless form. The BVP4C shooting method in MATLAB is employed to numerically and graphically solve these dimensionless ordinary differential equations. The results indicate that higher curvature parameter values correlate with increased velocity and temperature distribution profiles. A rise in nanoparticle volume fraction reduces the radial velocity profile but increases the temperature profile. Temperature distribution profiles increase with higher thermal radiation parameter and Biot number values, while higher thermal relaxation parameter values decrease temperature. Additionally, thermal distribution profiles rise with increasing values of both the time-dependent heat source constant and space-dependent heat source parameter.

Zadanie lokalizacji w sieciach kanalizacyjnych

Paper deals with the inverse / localisation task in sewer networks. An inverse problem is defined as the process of determining the causal factors from a set of observations. Applying this principle to the water management sector, it is often a matter of determining the location of the source of pollution based on monitored data on the concentration of pollution over time. From a mathematical point of view, to decrease the uncertainty of the inverse task solution, it is necessary to know the location of the source or the concentrations time course of the source (intensity function). In practice, we usually do not know any of these quantities, however, in the case of sewer networks we can accept some assumptions, which allow us to solve this inverse problem. Paper analyses specific conditions applied in the environment of sewer networks and describes proposed method for solving the source localisation task in the sewer network environment. The solution is based on numerical modelling of the pollution spreading in sewer system, accepting some process simplifications as well as assuming some source parameters. Typically, the solution of inverse task requires large and time consuming numerical simulations. This can be disadvantageous after recording the pollution event - a long calculation time reduces the efficiency and operability for the following pollution source reconnaissance. Therefore, our proposed method performs the necessary simulations in advance and the pollution source localisation after recording the pollution event is very fast, using a simple search and comparison in the simulation results database. The proposed method was tested on real sewer system and there were achieving promising results.

Directivity analysis and source parameter estimation: insights from the 2014 Arzew earthquake, Mw3.9, northwestern Algeria

Directivity analysis and source parameter estimation: insights from the 2014 Arzew earthquake, Mw3.9, northwestern Algeria