Comparative Numerical Analysis Research Articles

Numerical optimization of large-scale monotone equations using the free-derivative spectral conjugate gradient method

This study introduced an efficient method for solving non-linear equations. Our approach enhances the traditional spectral conjugate gradient parameter, resulting in significant improvements in the resolution of complex nonlinear problems. This innovative technique ensures global convergence and descent condition supported by carefully considered assumptions. The efficiency and effectiveness of the proposed method is highlighted by its outstanding numerical performance. To validate our claims, large-scale numerical simulations were conducted. These tests were designed to evaluate the capabilities of our proposed algorithm rigorously. In addition, we performed a comprehensive comparative numerical analysis, benchmarking our method against existing techniques. This analysis revealed that our approach consistently outperformed others in terms of theoretical robustness and numerical efficiency. The superiority of our method is evident in its ability to solve large-scale problems with accuracy in function evaluations, fewer iterations, and improved computational performance thereby, making it a valuable contribution to the field of numerical optimization.

Gyroid Lattice Heat Exchangers: Comparative Analysis on Thermo-Fluid Dynamic Performances

In recent years, additive manufacturing has reached the required reliability to effectively compete with standard production techniques of mechanical components. In particular, the geometrical freedom enabled by innovative manufacturing techniques has revolutionized the design trends for compact heat exchangers. Bioinspired structures, such as the gyroid lattice, have relevant mechanical and heat exchange properties for their light weight and increased heat exchange area, which also promotes the turbulent regime of the coolant. This work focuses its attention on the effect of the relevant design parameters of the gyroid lattice on heat exchange performances. A numerical comparative analysis is carried out from the thermal and fluid dynamic points of view to give design guidelines. The results of numerical analyses, performed on cylindrical samples, are compared to the experimental results on the pressure drop. Lattices samples were successfully printed with material extrusion, which is a low-cost and easy-to-use metal AM technology. For each lattice sample, counter pressure, heat exchange, and turbulence intensity ratio are calculated from the numerical point of view and discussed. At the end, the gyroid lattice is proven to be very effective at enhancing the heat exchange in cylindrical pipes. Guidelines are given about the choice of the best lattice, depending on the considered applications.

Magnetohydrodynamics Stagnation Point Flow of Hybrid Nanofluids with Distinct Base Fluid Over an Exponentially Extending Cylinder: A Numerical Comparative Analysis

Magnetohydrodynamics Stagnation Point Flow of Hybrid Nanofluids with Distinct Base Fluid Over an Exponentially Extending Cylinder: A Numerical Comparative Analysis

Comparative numerical analysis of dissipative radiative $$\left(ZnO{-}Ti{O}_{2}/PG\right)$$ hybrid nanofluid flow and heat transfer towards a nonlinear radial stretching sheet

Comparative numerical analysis of dissipative radiative $$\left(ZnO{-}Ti{O}_{2}/PG\right)$$ hybrid nanofluid flow and heat transfer towards a nonlinear radial stretching sheet

Impact properties of an end of life tires’ rubber. Numerical validation considering large strain and strain rate conditions

The objective of the authors is to demonstrate that the inclusion of renewed rubber from recycled end of life tires (ELT) can improve the performance of any structural system designed to dissipate impact energy. An interesting application would be its use in road safety barriers. This research starts with the rigorous characterization of the recycled material in order to include it in a viable numerical model. The authors presented, in a previous work (*), the experimental viscoelastic properties of recycled rubber, obtained under impact conditions. Bergström–Boyce (BB) nonlinear viscoelastic model was selected as the most suitable to fit the material behavior. This model is defined by nine material constants that are impossible to obtain, uniquely and directly, considering that only compression test results are available as input data. To overcome this challenge, optimization methods were applied resulting in as many sets of parameters as used optimization methods were considered and, moreover, remarkable differences between constants were observed. Solving this problem is the motivation of the present research: the validation of the optimization method by mean of the numerical evaluation of the obtained sets. The software considered for the numerical evaluation of impact tests (LS-DYNA®) had two slightly different implementations for the BB model: the original, based on the work published in 2009 by Dal & Kaliske and a more recent one implemented by Bergström, based on his works published in 1998 and 2000. This leads to a new question: which is the most appropriate implementation-optimization method for calibrating this material? This paper provides the answer to this question carrying out a complete comparative numerical analysis of all sets by means of explicit dynamics simulations. All calibrations, using the original LS-DYNA® implementation, were in perfect agreement with the experimental results. However, only one optimization method produced acceptable results for the most recent approach. A robust method to characterize recycled rubber from recycled tires using the Bergström–Boyce nonlinear viscoelastic model is presented, despite the experimental limitations (González-Vega et al. 2022).

AI-Powered Talent Acquisition: Enhancing Recruitment Processes in the Digital Age

The advent of AI-powered talent acquisition has revolutionized traditional recruitment methods, offering substantial improvements in efficiency, accuracy, and inclusivity. This paper explores the transformative impact of AI technologies on recruitment processes, comparing existing and proposed systems to highlight advancements and potential benefits. Key dimensions such as candidate sourcing efficiency, resume screening accuracy, candidate assessment relevance, predictive analytics performance, and promotion of diversity and inclusion are evaluated through numerical comparative analysis. The proposed system demonstrates significant improvements across all dimensions, achieving an overall score of 8.4/10 compared to the existing system's 5.8/10. Despite the promising benefits, challenges such as algorithmic bias and ethical considerations must be addressed to ensure fair and responsible AI usage in recruitment. The paper also suggests future enhancements, including the integration of emerging AI technologies, improved bias detection, personalized candidate experiences, real-time data analytics, and cross-cultural studies. This comprehensive examination underscores the potential of AI-powered talent acquisition to create more efficient, accurate, and inclusive recruitment processes, enabling organizations to build high-performing and diverse teams in the digital age. Keywords: AI-powered talent acquisition, recruitment processes, candidate sourcing, resume screening, candidate assessment, predictive analytics, diversity and inclusion, algorithmic bias, ethical AI, human resources technology.

Comparative Numerical Analysis of Keyhole Shape and Penetration Depth in Laser Spot Welding of Aluminum with Power Wave Modulation

Keyhole mode laser welding is a valuable technique for welding thick materials in industrial applications. However, its susceptibility to fluctuations and instabilities poses challenges, leading to defects that compromise weld quality. Observing the keyhole during laser welding is challenging due to bright process radiation, and existing observation methods are complex and expensive. This paper alternatively presents a novel numerical modeling approach for laser spot welding of aluminum through a modified mixture theory, a modified level-set (LS) method, and a thermal enthalpy porosity technique. The effects of laser parameters on keyhole penetration depth are investigated, with a focus on laser power, spot radius, frequency, and pulse wave modulation in pulsed wave (PW) versus continuous wave (CW) laser welding. PW laser welding involves the careful modulation of power waves, specifically adjusting the pulse width, pulse number, and pulse shapes. Results indicate a greater than 80 percent increase in the keyhole penetration depth with higher laser power, pulse width, and pulse number, as well as decreased spot radius. Keyhole instabilities are also more pronounced with higher pulse width/numbers and frequencies. Notably, the rectangular pulse shape demonstrates substantially deeper penetration compared to CW welding and other pulse shapes. This study enhances understanding of weld pool dynamics and provides insights into optimizing laser welding parameters to mitigate defects and improve weld quality.

Comparative Numerical Energy and Performance Analysis of Solar Photovoltaic and Solar Thermal Power Generation

This study analyses fixed and tracking solar photovoltaics and, solar thermal power. Performance in different locations was analysed for each configuration and technology using simulations based on a Typical Meteorological Year data. The study analysed a 25MWp solar photovoltaic and solar thermal power plants in each of the eleven selected locations in Zimbabwe. The performance of the solar photovoltaic and solar thermal power plants under different meteorological variables were assessed for all the selected locations. It was shown that different configurations together with different technologies have different conversion efficiencies. A high solar thermal conversion efficiency was found to be 18.718% in Gweru while it was 15.502% for solar photovoltaics in Mutare. The study also showed that highest insolation and clearness index values were found in Gweru. The average energy generated by the fixed photovoltaic collectors, tracking photovoltaic collectors and the Concentrating Solar Power plant were respectively 47.38GWh, 68.18GWh and 192.86GWh. There was a maximum percentage difference in the LCoE generated of 32.03% between the fixed PV collectors and the Concentrating Solar Power plant and a difference of 4.74% was realised between the tracking photovoltaics and Concentration Solar Power.

Comparative numerical analysis between butt and lap joints of Mg alloy friction stir welding with considering tilted tool effect

Magnesium (Mg) alloy, as an important lightweight structural metal, can be effectively joined by the friction stir welding (FSW) method. Understanding FSW temperature and material flow coupling process in butt and lap welding configurations has important theoretical significance. In this study, the tilted tool induced incomplete contact distance is calculated by process parameters and slip rate, and the deflection of the contact interface is related to the tool torque. The non-uniform boundary conditions are considered. The numerical model is proposed and experimentally validated by using the measured temperatures and thermo-mechanically affected zone (TMAZ) profiles. The comparative numerical analysis between butt and lap welding with three levels of process parameters is further conducted. The peak temperature and material flow velocity along the specified circumferences in FSBW are more than 10 K and 4 mm/s higher than these in FSLW, respectively. When the rotation rate increases from 600 rpm to 800 rpm, the peak temperature and material flow velocity along the specified circumferences increase about 20 K and 9 mm/s, respectively. When the welding speed decreases from 150 mm/min to 30 mm/min, the temperature and material flow velocity fluctuations along the specified circumference decreases about 25 K and 14 mm/s, respectively.

Optimal government subsidy strategy for fresh agricultural products supply chain under adverse weather: a two-stage dynamic game model

ABSTRACT To investigate the effects of various government subsidies on the decision of agricultural products supply chain under adverse weather, this paper depicts the random profit function of adverse weather affecting the output of fresh agricultural products. Then, both the centralised and decentralised decision-making models are set with various government subsidies, i.e. no subsidy, output subsidy, procurement subsidy, one-time subsidy to company and one-time subsidy to farmer. Through comparative analysis and numerical analysis, we explore the effects of adverse weather and different government subsidies on the supply chain decisions including planting effort, procurement price and retail price.

Seismic Resilience of Steel-Braced Frames Incorporating Steel Slit Dampers: A Review and Comparative Numerical Analysis

Steel dampers, specifically steel slit dampers (SSDs), are crucial for enhancing the seismic resilience of buildings by absorbing energy and mitigating damage. SSDs are celebrated for their ability to produce stable hysteretic behavior, owing to the inelastic deformation of their strips, alongside benefits such as lightness, ease of manufacture, and straightforward post-earthquake replacement. This research extensively examines SSD applications, design principles, and innovations in their modeling, optimization, and production processes. The literature highlights SSDs' consistent performance in resisting both compression and tension, their adaptability in strength, ductility, and energy dissipation through modifications in strip configurations and the superiority of non-prismatic and hourglass-shaped designs over traditional options. Numerical analyses have been conducted to assess the effectiveness of non-prismatic slit dampers in comparison to their prismatic counterparts within braced frames. Three distinct braced frame configurations have been analyzed: one with a diagonal brace without a damper, another featuring a uniform prismatic slit damper, and a third incorporating a non-prismatic slit damper with an hourglass shape. The analysis primarily compared these systems' hysteresis behavior, ductility, and energy dissipation capacities. Results indicate a significant enhancement in performance when utilizing non-prismatic slit dampers. Notably, these dampers exhibited a remarkable 69% increase in cumulative energy dissipation compared to prismatic ones. Furthermore, the study reveals that a steel slit damper-braced frame, when equipped with optimally designed slit geometries, can tolerate inter-story drifts in excess of 2% while simultaneously achieving a greater than 12% increase in energy dissipation efficiency. Doi: 10.28991/CEJ-2024-010-04-019 Full Text: PDF

Функционально-воксельное моделирование задачи Коши

The paper considers an approach to solving the Cauchy problem for an example of a partial differential equation of the first order under given boundary conditions by the functional voxel method (FVM). The proposed approach uses the accumulated experience of differentiation and integration into FV- modeling to obtain local geometric characteristics of triangular elements on the surface of the resulting function in the process of linear approximation. The analytical solution of a simple example of a partial differential equation of the first order for the Cauchy problem is analyzed. Based on the obtained analytical solution, FV-model is constructed for further comparison with the results obtained by means of FV-modeling. The algorithm for solving the example is described by means of FV-modeling. A visual and numerical comparative analysis is carried out to determine the difference between the obtained results of FV-modeling and the accepted standard. The main difference between solving such a problem by numerical methods is the results obtained. In numerical methods, the result is the value of the function at the approximation nodes, and the FV-model at the nodes contains local geometric characteristics (gradient components in a space enlarged by one), which makes it possible to obtain a nodal local function of an implicit form, as well as a differential local function of an explicit form. The proposed graphical representation of the function area on a computer provides not only visual visibility, but also compact storage compared to a traditional array of real numbers.

Numerical Study of Thermal Performance on Fin and Tube Heat Exchanger with Flat Rectangular and Sinusoidal Winglet Vortex Generators

Generation of vortices in the fin and tube heat exchanger is one of the common methods to reduce the air-side thermal resistance. This study deals with the enhancement of heat transfer in the air side using conventional rectangular and sinusoidal sine wave vortex generators. The vortex generators are placed in the downstream location of the tube in the common flow-down configurations and the range of Reynolds number is maintained about 400 to 1100. The results of the above vortex generators are compared with baseline configuration based on thermos-hydraulic criterion parameters like variation in the flow structure, variation in the temperature distribution, variation in the pressure distribution, variation in the friction factor, and overall thermal enhancement factor. Based on the comparative numerical analysis, sinusoidal and conventional rectangular winglet shows good heat transfer enhancement in that they have a large pressure loss penalty.

A numerical comparative analysis of methods for solving fractional differential equations

In this paper, we present two collocation methods utilizing subdivision schemes and Bernstein polynomials as their basis functions to solve Caputo-type fractional differential equations. These methods transform fractional differential equations into systems of linear equations, which can be solved using various suitable techniques. Notably, these methods are versatile, making them applicable to both boundary value problems and initial value problems. To demonstrate their effectiveness, we applied these methods to three test problems of fractional differential equations, including the Bagley-Torvik equation and fractional oscillation equation. Our results reveal that both methods provide a more accurate approximation to the exact solution when compared to various algorithms found in the existing literature, showcasing their efficiency, accuracy, and consistency.

A Comparative Numerical Analysis of Cold Plates for Thermal Management of Chips With Hotspots

Abstract Thermal and hydraulic performances of seven water-cooled minichannel cold plates with different internal structures are compared using numerical analysis. Recent increasing demands for high-performance computing have led to serious challenges in the thermal management of electronic devices. In addition to dangerous on-chip temperatures, heterogeneous integration and local regions of elevated temperatures (hotspots) lead to nonuniform chip-level temperature distributions. As a result, the lifespan and reliability of electronic devices are adversely impacted. Due to the limitation of the air-cooled heat sinks, several new methods, such as liquid-cooled microchannel cold plates are developed to remedy these challenges. The objective of this work is to provide a comparative numerical study of the effectiveness of different minichannel cold plate internal structures in the thermal management of a chip with a nonuniform power map and a hotspot. Cold plate thermal resistance, on-chip temperature uniformity, and pump power were the metrics used for this comparison. For four coolant inlet flow rates within the laminar regime, it is seen that increasing the inlet flowrate enhances the thermal resistance of all cold plate designs while creating less uniformity in chip-level temperature distribution relative to the conventional straight microchannels. Concentrating pin fins on the hotspot showed a 7.2% reduction in thermal resistance, despite increasing temperature nonuniformity by about 7.6%. However, it is observed that hotspot-focused pin fins are more effective in lowering the chip's maximum temperature. Obtaining lower chip-level nonuniformity may be possible by modifying the inlet and outlet conditions of the cold plates.

FACTORS AFFECTING CREDIT RISK FOR INDIVIDUAL CUSTOMERS AT VIETNAM BANK FOR AGRICULTURE AND RURAL DEVELOPMENT, BINH THANH BRANCH, HO CHI MINH CITY

The main objective of the study is to determine the factors affecting credit risk for individual customers at Vietnam Bank for Agriculture and Rural Development, Binh Thanh Branch, HCMC. In order to achieve the research objectives, the author used comparative and absolute numerical analysis methods; Descriptive statistics method; Probit regression method to identify factors affecting credit risk. The research results show that of 09 independent variables included in the research model, 05 variables correlated with the dependent variable which is the borrower's financial ability (X1); Industry (X3); Checking and supervising loan debts (X4); Experience of credit officer (X5); Number of dependents (X8). In particular, the variable that is positively correlated with the dependent variable is the number of dependents; The borrower's industry variable is the one that has the strongest impact on the dependent variable, followed by the borrower's financial ability. Based on the research results, the author proposes a number of solutions to improve credit efficiency for Vietnam Bank for Agriculture and Rural Development, Binh Thanh Branch as follows: Selection of credit officers experienced; Assess the number of dependents; Credit officers enhance inspection and supervision of loans; Increasing the financial security of borrowers; Focus on the main business that generates the income of customers when reviewing loan applications.

FACTORS AFFECTING CREDIT RISK OF INDIVIDUAL CUSTOMERS AT BANK FOR FOREIGN TRADE OF VIETNAM CAN THO BRANCH

The study "Factors affecting individual customer credit risk at Can Tho VCB will be conducted from 2021-2023. The study used comparative and absolute numerical analysis methods; Descriptive statistics and Probit regression methods to identify factors affecting credit risk. The research results show that of the 09 independent variables included in the research model, 05 variables correlate with the dependent variable, which is the borrower's financial ability (X1); Occupation (X3); Check and monitor loan debt (X4); Experience of credit officers (X5); Number of dependents (X8). In particular, the variable that has a positive correlation with the dependent variable is the number of dependents; The borrower's industry variable is the variable that has the strongest impact on the dependent variable, followed by the borrower's financial ability variable. Based on the research results, the author proposes several solutions to improve credit efficiency for Can Tho VCB such as selecting experienced credit officers; Assessing the number of dependents; Credit officers strengthening inspection and supervision of loan debt; Increasing the financial security of borrowers; Pay attention to the main industry that generates customers' income when reviewing loan applications.

Deployment Integration Strategy for Daytime Radiative Cooling Materials: A Comparative Numerical Analysis of Roof Cooling and Water-Cooling Panels

Daytime radiative cooling has emerged as a promising solution for continuous passive cooling. While significant progress has been made in material developments, questions persist regarding the potential large-scale deployment of this technology. Among the potential applications, two predominant uses of daytime radiative cooling materials arc under study: passive roof cooling and water-cooling panels. In the present study, a numerical assessment to compare the benefits of both integration schemes for passive daytime radiative cooling materials is conducted. These findings suggest adjusted approaches based on climatic considerations for the optimal deployment of daytime radiative cooling technologies worldwide.

Beam Coupling Impedance Contribution of Flange Aperture Gaps: a Numerical Study for Elettra 2.0

The accurate analysis of any possible source of beam instability is mandatory for the design of a new particle accelerator, especially for high-current and ultra-low emittance synchrotrons. In the specific case of instabilities driven by the coupling between the charged particle beam and the electromagnetic field excited by the beam itself, the corresponding effect is estimated through the beam coupling impedance. The modeling of this effect is essential to perform a rigorous evaluation of the coupling impedance budget able to account for all devices present in the entire machine. To deal with this problem, this paper focuses on the estimation of the contribution of the joints lying between the different vacuum chamber sections, by performing a comparative numerical analysis that takes into account different aperture gaps between the flanges. The results point out the criticality of many small-impedance contributions that, added together, must be lower than a predefined impedance threshold.

Numerical Comparative Analysis of the Influence of Fuel Micro-Hole Geometry on the Combustion Characteristics of Hydrogen Micro-Mixing Combustor

Numerical Comparative Analysis of the Influence of Fuel Micro-Hole Geometry on the Combustion Characteristics of Hydrogen Micro-Mixing Combustor