Comparative Numerical Analysis Research Articles

A Comparative Numerical Study and Stability Analysis for a Fractional-Order SIR Model of Childhood Diseases

The objective of this work is to examine the dynamics of a fractional-order susceptible-infectious-recovered (SIR) model that simulate epidemiological diseases such as childhood diseases. An effective numerical scheme based on Grünwald–Letnikov fractional derivative is suggested to solve the considered model. A stability analysis is performed to qualitatively examine the dynamics of the SIR model. The reliability and robustness of the proposed scheme is demonstrated by comparing obtained results with results obtained from a fourth order Runge–Kutta built-in Maple syntax when considering derivatives of integer order. Graphical illustrations of the numerical results are given. The inaccuracy of some results presented in two studies exist in the literature have been clearly explained. Generalizing of the cases examined in another study, by considering a model with fraction-order derivatives, is another objective of this work as well.

Comparison of DC Electric Arc Furnace Chaotic Models for Power Quality Indices Assessment

Due to their particular feature, direct current (dc) electric arc furnace (EAF) installations are peculiar loads that cause moderate to severe power quality (PQ) disturbances in the feeding power systems. Among them, voltage fluctuations and waveform distortions are the most impactful ones, and they should be adequately addressed in order to mitigate the detrimental effects. Several types of models have been developed in order to evaluate the effects of EAFs on networks, and chaotic models have been specifically recognized as suitable tools to evaluate the impact of EAFs in terms of PQ disturbances. This article compares the performance of three chaotic models (Chua, Lorenz, and Rössler) aiming at estimating PQ indices values of dc EAFs. The procedure exploits a block diagramming tool of the dc EAF installation and minimizes the deviation of estimated PQ indices from the actual ones through a new Monte Carlo optimization procedure, performed upon the parameters of the three chaotic models. To comply with the time-varying nature of the current and voltage waveforms in a dc EAF installation and with the wide presence of interharmonics, traditional, and advanced PQ indices are considered in this article. Actual data collected at an Italian dc EAF installation are used to conduct a numerical comparative analysis and to validate the effectiveness of the models in estimating the PQ disturbances.

Digital comparative analysis of simulation results of radioactive deposition field of nuclear explosion

The radioactive settlement of nuclear explosion is simulated by Lagrange particle diffusion model. The simulated settlement map and the measured data map are digitally extracted into the same format. The effectiveness measurement (MOE) method and normalized absolute difference (NAD) method are used to conduct numerical comparative analysis between each dose simulation area and the measured area.

Modeling of welding arc power supply diagrams in Matlab / Simulink

Purpose. Creation of virtual blocks and simulation laboratory stands for the study and comprehensive research of the dynamic properties of welding power supplies. Methodology. Review of literary sources on the subject, simulation modeling of electromagnetic processes in the MATLAB software environment, comparative analysis of obtained and available data. Findings. The comparative analysis of means of modeling of power sources of a welding arc is executed. One of the main parameters by which the environments were compared is functionality. Among the considered simulators, Simulink of the MATLAB software environment is the most effective one in the considered systems modeling. Using special features, its user can not only simulate, but also analyze the operation of the over time installation. Mathematical and functional models of welding arc power supplies were built using SimPowerSystems elements and blocks from the Simulink library with the involvement of the MATLAB system itself, which significantly expands the possibilities for such systems modeling. Mathematization of certain processes to some extent shows the level of reliability of the results and the degree of their scientific development. The developed models act as a laboratory, which allows you to set and explore any modes and characteristics. Numerical experiments and comparative analysis of numerical and field experiments are given. Experimental verification of the obtained results on specific examples showed the relevance of the problem and the correctness of its solution. Further research is related to the expansion of the range of simulated power sources of the electric arc, a comprehensive study of their dynamic properties and basic characteristics, experimental verification of the developed models, as well as comparative analysis and development of recommendations for model improvement. Originality. The method of circuit modeling of general-purpose electrical and electronic circuits was further developed by extending it to a new class of objects - the power supply system of electrical installations. Practical value. Construction of mathematical and functional models of complex systems with the involvement of MATLAB allows to take into account their main features, significantly expands the possibilities for modeling, study and research of power supplies. Based on the proposed approach, simulation laboratory stands of specific power supplies were developed and built, which allow to set and study any modes and characteristics.

Maximum Power Extraction from Wind Turbines Using a Fault-Tolerant Fractional-Order Nonsingular Terminal Sliding Mode Controller

This work presents a nonlinear control approach to maximise the power extraction of wind energy conversion systems (WECSs) operating below their rated wind speeds. Due to nonlinearities associated with the dynamics of WECSs, the stochastic nature of wind, and the inevitable presence of faults in practice, developing reliable fault-tolerant control strategies to guarantee maximum power production of WECSs has always been considered important. A fault-tolerant fractional-order nonsingular terminal sliding mode control (FNTSMC) strategy to maximize the captured power of wind turbines (WT) subjected to actuator faults is developed. A nonsingular terminal sliding surface is proposed to ensure fast finite-time convergence, whereas the incorporation of fractional calculus in the controller enhances the convergence speed of system states and simultaneously suppresses chattering, resulting in extracted power maximisation by precisely tracking the optimum rotor speed. Closed-loop stability is analysed and validated through the Lyapunov stability criterion. Comparative numerical simulation analysis is carried out on a two-mass WT, and superior power production performance of the proposed method over other methods is demonstrated, both in fault-free and faulty situations.

Radiative corrections to the lepton current in unpolarized elastic lp-interaction for fixed $$Q^2$$ and scattering angle

The kinematical difference between the description of radiative effects for fixed $Q^2$ vs a fixed scattering angle in the elastic lepton-proton ($lp$)-scattering is discussed. The technique of calculation as well as explicit expressions for radiative corrections to the lepton current in unpolarized elastic $lp$-scattering for these two cases are presented without using an ultrarelativistic approximation. A comparative numerical analysis within kinematic conditions of Jefferson Lab measurements and MUSE experiment in PSI is performed.

Analysis of typical PLC pulses for sensing high-impedance faults based on time-domain reflectometry

This paper focuses on a comprehensive analysis of typical power line communication (PLC) pulses for sensing high impedance faults in power distribution networks (PDNs) when the pulse compression time-domain reflectometry (TDR) system applies. In this sense, closed-form expressions for the PLC pulses, namely Hermitian symmetric orthogonal frequency-division multiplexing (HS-OFDM), impulsive ultra-wideband (UWB), and chirp spread spectrum (CSS), and their corresponding autocorrelation functions are presented. Also, parameters based on radar theory (e.g., range resolution, pulse compression ratio, reflectogram distortion, and maximum unambiguous range) are introduced to evaluate the usefulness of these PLC pulses for providing proper TDR measurements (reflectograms). A comparative numerical analysis considering frequency bands that comprise narrowband and broadband PLC systems, with a highlight on well-established regulatory constraints, is discussed. Numerical results show that the use of UWB pulses yields a larger number of reflectograms in a given time interval, while HS-OFDM and CSS pulses provide higher reflectogram quality and better resolution, under the same conditions. Also, narrowband PLC systems are suitable for the majority of PDNs, with the use of broadband PLC ones left for attaining high resolutions at short distances.

Comparative numerical analysis of Maxwell's time-dependent thermo-diffusive flow through a stretching cylinder

The study of fluid flow around a stretching cylinder has great importance, due to its broad range of applications in engineering and industries. In this article, unsteady incompressible Maxwell nanofluid flow around a stretching cylinder escorted by unfluctuating suction/injection impact has been scrutinized. The Maxwell nanofluid nature is described through Buongiorno's model. The dimensionless system of ODEs is diminished from the system of modeled equations, through a proper similarity transformation. The obtained system of ordinary differential equations is further numerically computed with PCM (Parametric continuation method). For the validity of the results, the outcomes are compared with Matlab package boundary value solver (bvp4c). The physical entities influence on velocity, energy, concentration, and magnetic strength profiles are sketched and discussed. It has been perceived that the momentum of mass transmission is significantly increases with the effects of thermophoresis parameter, while the velocities in angular and radial directions are reducing with enlarging of viscosity parameter. The influences of thermal radiation Rd and Brownian motion are particularly more valuable to enhance the temperature of the fluid. Furthermore, by applying the magnetic field a resistive force is formed, which reduced the velocities and boosted the temperature of the fluid.

Comparative numerical analysis between the multipole expansion of optical force up to quadrupole terms and the generalized Lorenz–Mie theory

We explore graphical comparisons of the radiation forces calculated via the multipole expansion of optical force up to electric and magnetic quadrupole terms with the rigorous and exact generalized Lorenz–Mie theory (GLMT) on a homogeneous spherical particle. Examples are presented for a Gaussian beam in its fundamental mode and for a higher-order ideal Bessel beam. We also compute forces for a nondiffracting structured beam composed of a discrete superposition of copropagating Bessel beams with the same order and frequency, known in the literature as frozen waves. The results show a great agreement for moderately sized Mie particles, up to radius of about one-fifth the wavelength, thus suggesting an intrinsic connection between both methods and the possibility to extend recent theoretical works related to the identification between the Rayleigh limit of the GLMT and the dipole theory of forces.

Historical foundations and contemporary expressions of a right to health care in Circumpolar Indigenous contexts

Although numerous comparative Indigenous health policy analyses exist in the literature, to date, little attention has been paid to comparative analyses of Circumpolar health policy and the impact these policies may have on Indigenous peoples’ rights to health. In this article, we ground our discussion of Indigenous peoples’ right to access culturally appropriate and responsive health care within the context of the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP). Under UNDRIP, signatory states are obligated to guarantee that Indigenous peoples have access to the same services accessible to all citizens without discrimination. Signatory states must also guarantee access to services that are grounded in Indigenous cultures, medicines, and practices and must address Indigenous peoples’ determinants of health at least to the same extent as their national counterparts. Our analysis finds that the implementation of this declaration varies across the Circumpolar north. The United States recognizes an obligation to provide health care for American Indian and Alaska Native people in exchange for the land that was taken from them. Other countries provide Indigenous citizens access to care in the same health care systems as other citizens. Intercultural models of care exist in Alaska and to some extent across the Canadian territories. However, aside from Sámi Norwegian National Advisory Unit on Mental Health and Substance Use in northern Norway, intercultural models are absent in Nordic countries and in Greenland. While Russia has not ratified UNDRIP, Russian policy guarantees access to health care to all citizens, although access is particularly limited in rural and remote environments, including the Russian Arctic. We conclude that Circumpolar nations should begin and/or expand commitments to culturally appropriate, self-determined, access to health care in Circumpolar contexts to reduce health inequities and adhere to obligations outlined in UNDRIP.

Numerical analyses of a base connection for a thin-walled cold-formed profile column

Thin-walled cold-formed steel structures tend to gain more attention in the civil engineering field. Ground-floor dwellings, as well as factory warehouses represent the most frequent use of these structural systems. However, due to the inherent flexibility of thin-walled cold-formed steel elements, the designer has to take into consideration the possibility of large deformations occurrence, especially in the case of structures with large openings. Such deformations may lead to significant stresses at the level of the connection joints between elements or between elements and the foundation block. The paper presents a comparative numerical analysis based on the finite element method to assess the efficiency of a connection joint between the columns of a portal frame and the foundation block. The linear and nonlinear analyses were carried out by means of Robot Structural Analysis and Ansys. The column is made of two thin-walled cold-formed C shape profiles positioned back-to-back. The efficiency was assessed both from a stress-state point of view in the column and in the connection parts, as well as from the point of view of the manufacturing process and implementation. Significant differences were observed regarding the stress distribution in the nonlinear analysis.

Effect of Abstinence on Psychological Distress Scores, Social Dysfunction Scores, Total General Health Questionnaire Scores-12, and Total Quality of Life Scores in Men with Methamphetamine Dependence in Therapeutic Community

AIM: We looked for differences in abstinence influence on Psychological Distress Scores, Social Dysfunction Scores, Total General Health Questionnaire – 12 (GHQ-12), and Total Quality of Life Scores on men with Methamphetamine dependence in the Therapeutic Community. METHODS: This study was conducted a numerical comparative analytical analysis paired with twice measurements with subject retrieval done using consecutive sampling. The participant of this study was 47 subjects who selected by inclusion and exclusion criteria. RESULTS: Found psychological distress score of the abuser was p ˂ 0.001, different with social dysfunction score there was no significant difference where the score was p = 0.062, the total GHQ-12 score was a significant difference where the score was p = 0.025 while in the total quality of life score (SF-36) there was a significant difference with the score of p ˂ 0.001. CONCLUSIONS: After abstinence, quarantine was found to improve attitude, behavior, cognitive, and social function such as appropriate communication and active social relationship with others compared with before abstinence quarantine.

Сравнительный анализ качества робастных модификаций метода главных компонент при сжатии коррелированных данных

Principal component analysis is one of the methods traditionally used to solve the problem of reducing the dimensionality of a multidimensional vector with correlated components. We constructed the principal components using a special representation of the covariance or correlation matrix of the indicators observed. The classical principal component analysis uses Pearson sample correlation coefficients as estimates of the correlation matrix elements. These estimates are extremely sensitive to sample contamination and anomalous observations. To robustify the principal component analysis, we propose to replace the sample estimates of correlation matrices with well-known robust analogues, which include Spearman's rank correlation coefficient, Minimum Covariance Determinant estimates, orthogonalized Gnanadesikan --- Kettenring estimates, and Olive --- Hawkins estimates. The study aims to carry out a comparative numerical analysis of the classical principal component analysis and its robust modifications. For this purpose, we simulated nine-dimensional vectors with known correlation matrix structures and introduced a special metric that allows us to evaluate the quality of data compression. Our extensive numerical experiment has shown that the classical principal component analysis boasts the best compression quality for a Gaussian distribution of observations. When observations are characterised by a Student's t-distribution with three degrees of freedom, as well as when a cluster of outliers, individual anomalous observations, or symmetric contaminations described by the Tukey distribution are present in the data, it is the Gnanadesikan --- Kettenring and Olive --- Hawkins estimates modifying the principal component analysis that show the best compression quality. The quality of the classical principal component analysis and Spearman’s rank modification decreases in these cases

A Comparative Numerical Analysis on the Effect of Welding Consumables on the Ballistic Resistance of SMAW Joints of Armor Steel

In the present investigation, a comparative study of ballistic impact behavior of Armox 500T (base metal) and its weldments prepared by low hydrogen ferrite (weldment-1) and austenitic stainless steel (weldment-2) consumables against 7.62 AP bullet has been performed with the help of finite element analysis code Abaqus 2017. Further, the result is validated with the experimental results. The experiment has been performed on the base metal, weldment-1, and weldment-2 against 7.62 AP bullet. Further, a two-dimensional explicit model has been developed for given purpose to simulate the bullet penetration at such high strain rate (103 s−1). Both bullet and plate are considered as deformable. Experimental results revealed that the depth of penetration in the base metal, weldment-1, and weldment-2 is 10.93, 13.65, and 15.20 mm respectively. Further computational results revealed that the depth of penetration of base metal, weldment-1, and weldment-2 is 10.11, 12.87, and 14.60 mm, respectively. Furthermore, weldment-1 shows more resistance against 7.62 AP bullet than weldment-2 in experimentation as well as FEA results. The percentage difference between experimental and FEA results are less than 10% which shows the prediction capability of FEA models. A feasibility analysis has been presented for using the welding consumables to weld the Armox 500T plate. Finally, in terms of ballistic resistance, the low hydrogen ferrite consumables are more appropriate than austenitic stainless-steel electrodes.

SIMULATION-BASED ANALYSIS OF THE EFFECT OF GREEN ROOFS ON THERMAL PERFORMANCE OF BUILDINGS IN A TROPICAL LANDSCAPE

Apart from the ever- increasing population of most tropical urban cities, high ambient temperature, deteriorated comfort conditions, highly polluted environments are but a few of the problems these cities are confronted with. In the long run, increase energy demands both for production and the provision of comfortable spaces becomes necessary even though it’s a very scarce resource. It is widely known that Urban heat island (UHI) can significantly affect building’s thermal performance and as such, this study was conducted to find out how green roof which is a mitigating factor can reduce the thermal discomfort in indoor spaces. By means of dynamic simulation in EnergyPlus software, a numerical comparative analysis between eight scenarios was done in a tropical climate of Ghana, taking into account climatological, thermal, and hydrological variables. Two factors: Leaf Area Index (LAI) and Soil depth were the main determinants of the comparative analysis. From the results, 5 out of the 8 scenarios was seen to all have performed better leading to a 1.5°C temperature reduction. Out of the 5, LAI5/70-150mm and LAI2/500mm suggest that at every point, there could be a reduction in indoor temperature if either LAI is larger or substrate depth is deep. A larger LAI and a deeper depth could also produce a favorable results (LAI5/500mm) though after a certain threshold, their effect weakens. Based on the findings, it is highly recommended that green roofs becomes part of the solution towards the fight against indoor thermal discomfort and not mechanical ventilation which could have a dire consequence on an already scare resource which is energy.

Procurement modes for emergency supplies in the presence of disaster and commercial demands

Abstract This paper studies alternative procurement modes for emergency supplies in the presence of a public sector and a private supplier. A key feature of such a supply chain is that the private supplier must consider commercial demand in addition to disaster demand. Three procurement modes are analysed: an option mode (OM), an order-before-disaster mode (OBDM) and a procurement-after-disaster mode (PADM). We provide the optimal decisions associated with these three modes. Theoretical results in the OM show that a large order is not always better for the private supplier. From theoretical and numerical comparative analyses, no mode is absolutely superior. For the public sector, there are two thresholds. When the disaster probability is less than the low threshold, the revenues of all procurement modes are the same; when the disaster probability is larger than the high threshold, the OBDM has the highest revenue; otherwise, the OM has the highest revenue. However, for the private supplier, the PADM always has the highest revenue.

A Hybrid Dynamical Modeling Framework for Shape Memory Alloy Wire Actuated Structures

In this letter, a hybrid model for single-crystal Shape Memory Alloy (SMA) wire actuators is presented. The result is based on a mathematical reformulation of the Müller-Achenbach-Seelecke (MAS) model, which provides an accurate and interconnection-oriented description of the SMA hysteretic response. The strong nonlinearity and high numerical stiffness of the MAS model, however hinder its practical use for simulation and control of complex SMA-driven systems. The main idea behind the hybrid reformulation is based on dividing the mechanical hysteresis of the SMA into five operating modes, each one representing a different physical state of the material. By properly deriving the switching conditions among those modes in a physically-consistent way, the MAS model is effectively reformulated within a hybrid dynamical setting. The main advantage of the hybrid reformulation is the possibility of describing the material dynamics with a simplified set of state equations while maintaining all benefits of the physics-based description offered by the MAS model. After describing the novel approach, simulation studies are conducted on a flexible robotic module actuated by protagonist-antagonist SMA wires. Through comparative numerical analysis, it is shown how the hybrid model provides the same accuracy as the MAS model while saving up to 80% of the simulation time. Moreover, the new modeling framework opens up the possibility of addressing SMA control from a hybrid systems perspective.

Comparative Numerical Analysis between Two Types of Orthodontic Wire for the Lingual Technique, Using the Finite Element Method.

In the lingual orthodontic technique, there are two paradigms regarding the type of wire used. Regardless of the material or gauge, some orthodontists choose to use the straight wire and resin and bond it to the surface of the tooth; they call it compensations. Other orthodontists prefer to bend the wire, giving it a mushroom shape. There is no specific indication for the use of each type of wire, so orthodontists use them according to their criteria. The present study establishes the bases so that it is possible to find the indications for each type of wire. A clinical trial of a lingual orthodontic patient was used. To carry out the comparative study, a straight arch was placed in his right arch and a mushroom arch in the left arch. Using 3D imaging, a high-biofidelity biomodel of the patient's mandible was generated, with which the FEM analysis was performed, which allowed comparing the reactions of the mandibular bone and appliances with the different arches. It was found that, on the side with the straight arch, there were greater deformations, and in the mushroom arch, there were greater stresses. With this, it is possible to find which clinical cases in each type of wire are indicated.

Seismic performance of spatial beam-column connections in steel frame

This paper presents a developed spatial beam-column connection in steel frame which is suitable for widely used H-section column and beam. To provide a first insight into the hysteretic responses of the proposed spatial connections, a numerical comparative analysis was conducted for the proposed connections and also the traditional connections after verifying the validity of the finite element methods. The normalized moment versus the story drift rotation hysteretic loops, energy dissipation capacity, failure modes, Mises index (MI), triaxiality index (TI) and rupture index (RI) distribution at the beam flange welds were discussed in detail. The proposed connection could significantly improve the hysteretic performance of the strong–axis connections and also the weak-axis connections in terms of the stiffness, strength, energy dissipation capacity, and could effectively move the beam plastic hinges away from the beam-column interface. The proposed spatial connection has the characteristics of “strong connection and weak member”. The spatial loading exerted negligible effects on the structural behavior of the beam-column connections for the considered sizes and loading methods. It is recommended that the anti-lamellar tearing steel plate could be used for the side plates in the proposed connections to prevent the tearing fracture.

A novel strategy for comparative numerical analysis of the response of buried composite and steel pipes subjected to realistic loading scenarios: FEA in cooperation with Taguchi approach

The main objective of this paper is to perform a comparative Finite Element Analysis (FEA) of the mechanical behaviour of buried GRE composite and X60 steel pipelines under various scenarios with realistic loadings conditions that may be experienced by actual buried pipes. The response of buried pipes is influenced by various factors and their synergistic effects, so in this study, with a novel strategy, a procedure is developed to investigate these synergisms. Firstly, after constructing FE models and validating them with using analytical and previous numerical models available in the literature, these FE models are developed to collaborate with the statistical methods and afterwards, they are taken into account as virtual experiments. FE analysis in cooperation with the Taguchi approach is used to obtain a well-planned set of experiments to get a targeted study. Finally, the obtained results can be used to supply a better understanding of the failure process of buried pipes and optimization of design features of future buried pipelines which may provide a significant insight for installation designs, failure prevention, maintenance strategies for diminishing costs and prevention from catastrophic occurrences. The perspective of the presented strategy shows that it is more efficient and comprehensive than preceding procedures. Both GRE and X60 buried pipes are studied under pseudo-earthquake effects. Results show composite pipes are an appropriate option for earthquake-prone areas.