Comparative Numerical Analysis Research Articles

Command smoothing-proxy sliding mode control of hydraulic servo system considering structural flexibility

In this study, a command smoothing-disturbance observer-based proxy sliding mode control (CS-DPSMC) method is proposed for a class of hydraulic servo systems with structural flexibility. First, to alleviate the influence of residual vibration due to structural flexibility, command smoothing method (CS) is used to modify the desired trajectory; Then, a nonlinear disturbance observer-based proxy sliding mode controller (DPSMC) is developed so as to make the hydraulic actuator track the desired trajectory. Besides, the control signal is continuous because the discontinuous sign function is theoretically canceled. Therefore, high-frequency unmodeled dynamics of flexible structures will not be excited. According to the passivity theory and Lyapunov theory, the stability of the control system is proven. The effectiveness of the proposed algorithm is verified by comparative numerical analysis.

Comparative numerical analysis of the response of laterally loaded pile in coral and silica sands

Comparative numerical analysis of the response of laterally loaded pile in coral and silica sands

Pengaruh Pemberian Platelet-Rich Plasma Terhadap Derajat Keparahan Psoriasis Vulgaris

Psoriasis vulgaris is an autoimmune disease that is influenced by multifactor, namely environmental, genetic (HLA-Cw6), and immune system dysregulation (IL-17 or IL-22), resulting in increased proliferation of keratinosit in the epidermis. Histologically characterized by parakeratosis, hyperkeratosis, elongated rete ridge, Monro micro abscess, and Kogoj micro abscess. The clinical picture is red patches with thick scales, especially in the trauma area. Platelet Rich Plasma (PRP) is an autologous preparation of platelets that strengthens in plasma and is a powerful anti-inflammatory agent. The immunomodulatory and anti-inflammatory effects of PRP are believed to play a role in the treatment of chronic inflammation patients. One of the important mediators in the pathogenesis of psoriasis is nuclear factor kappa B (NF-κB) and PRP exerting an inhibitory effect on NF-κB. The aim of the study was to assess the effect of PRP on the severity and quality of life of psoriasis vulgaris patients. The design of this study is a paired numerical comparative analysis using two groups with two measurements. The research design was a randomized, undisguised clinical trial and a parallel design. The study lasted for 6 weeks. Sampling was done by total sampling involving 20 psoriasis Vulgaris patients, then divided into two groups: intervention group and control group. The test group received 2 PRP injections and topical combination therapy (salicylic acid 3% + Vaseline album cream), while the control group only received topical combination therapy. The results of this study found a decrease in PASI and DLQI scores in the intervention group compared to the control group (p<0.005). This study concludes that the administration of PRP can reduce the severity of psoriasis Vulgaris as well as improve the quality of life of psoriasis Vulgaris patients.

Noble Approach on Sensor Fused Bio Intelligent Path Optimisation and Single Stage Obstacle Recognition in Customized Mobile Agent

Optimized PTP (Point to Point) Navigation by customized mobile agent constitutes extensive research domain in Machine Intelligence. Distinct Literature survey confirms the proposal of SLAM (Simultaneous Localization And Mapping) mediated sensor usage for visual data collection in a particular GPS (Global Positioning System) - denied indoor environment. This has been further followed by fused data collection using multi sensor for obtaining long time and high precision localization and obstacle detection in MRN (Mobile Robot Navigation). This paper proposes an idea to incorporate machine learning module for data modeling so that the obstacle detection and identification results in relatively more precise, accurate and efficient. The comparative numerical analysis has been presented to establish the proposed methodology. Along with this, Fusion SLAM algorithm has been created and proposed which combines features of both 2D LiDAR (Light Detection And Ranging) and RGB-D (Red, Green, Blue Depth) SLAM, resulting in visual reference of combined detected periphery and reconstructed 3D depth of on-path obstacles. The aforesaid procedure is further extended with integration of Bio Intelligent path planning approach. Experimental analysis carried out with sample candidate functions with respect to concerned mobile robot and considered indoor environment has been presented which would prove to be important citation for further research in the domain of collision-free optimum MRN.

Comparative numerical analysis of heat transfer in masonry prisms in a fire situation

Resumo Opresente trabalho busca analisar numericamente a transferência de calor em prismas de alvenaria com blocos cerâmicos em situação de incêndio. Três tipos de abordagens foram consideradas: modelo homogeneizado com base na NBR 15220-2:2022, modelo detalhado com propriedades termofísicas constantes e modelo detalhado com propriedades térmicas variando em função da temperatura. Para o processo da homogeneização é proposto um programa denominado “THC NBR15220-2”. Esse programa foi desenvolvido em Matlab e calcula a homogeneização das propriedades segundo a NBR 15220-2:2022. Os modelos numéricos foram realizados utilizando o método dos elementos finitos (MEF) no software Abaqus. O incêndio foi simulado utilizando a curva padronizada ISO 834:1999. Foram coletadas as temperaturas na face não exposta ao fogo no tempo final de exposição de 4 horas. Os resultados mostraram que o prisma com maior número de vazios e menor relação área líquida e área bruta apresentou melhor desempenho térmico em situação de incêndio. O modelo detalhado com propriedades térmicas variando com a temperatura, como sugerido por normas internacionais.

Comparative Numerical Analysis of Three-Dimensional Flow in the Opening Process of the Single-Disc Butterfly Valves

Comparative Numerical Analysis of Three-Dimensional Flow in the Opening Process of the Single-Disc Butterfly Valves

On Non-Symmetric Fractal-Fractional Modeling for Ice Smoking: Mathematical Analysis of Solutions

Drugs have always been one of the most important concerns of families and government officials at all times, and they have caused irreparable damage to the health of young people. Given the importance of this great challenge, this article discusses a non-symmetric fractal-fractional order ice-smoking mathematical model for the existence results, numerical results, and stability analysis. For the existence of the solution of the given ice-smoking model, successive iterative sequences are defined. The uniqueness of the solution Hyers–Ulam (HU) stability is established with the help of the existing definitions and theorems in functional analysis. By the utilization of two-step Lagrange polynomials, we provide numerical solutions and provide a comparative numerical analysis for different values of the fractional order and fractal order. The numerical simulations show the applicability of the scheme and future prediction and the effects of fractal-fractional orders simultaneously.

Forecasting of Wind Speed and Power through FFNN and CFNN Using HPSOBA and MHPSO-BAACs Techniques

Renewable Energy Sources are an effective alternative to the atmosphere-contaminating, rapidly exhausting, and overpriced traditional fuels. However, RESs have many limitations like their intermittent nature and availability at far-off sites from the major load centers. This paper presents the forecasting of wind speed and power using the implementation of the Feedforward and cascaded forward neural networks (FFNNs and CFNNs, respectively). The one and half year’s dataset for Jhimpir, Pakistan, is used to train FFNNs and CFNNs with recently developed novel metaheuristic optimization algorithms, i.e., hybrid particle swarm optimization (PSO) and a Bat algorithm (BA) named HPSOBA, along with a modified hybrid PSO and BA with parameter-inspired acceleration coefficients (MHPSO-BAAC), without and with the constriction factor (MHPSO-BAAC-χ). The forecasting results are made for June–October 2019. The accuracy of the forecasted values is tested through the mean absolute error (MAE), mean absolute percentage error (MAPE), and root mean square error (RMSE). The graphical and numerical comparative analysis was performed for both feedforward and cascaded forward neural networks that are tuned using the mentioned optimization techniques. The feedforward neural network was achieved through the implementation of HPSOBA with a mean absolute error, mean absolute percentage error, and root mean square error of 0.0673, 6.73%, and 0.0378, respectively. Whereas for the case of forecasting through a cascaded forward neural network, the best performance was attained by the implementation of MHPSO-BAAC with a MAE, MAPE and RMSE of 0.0112, 1.12%, and 0.0577, respectively. Thus, the mentioned neural networks provide a more accurate prediction when trained and tuned through the given optimization algorithms, which is evident from the presented results.

Influence of the soil base on the stress-strain state of a large-span building with a cylinder-and-slab roof

The authors consider finite element models of a large-span building with a cylinder-and-slab roof as a large spatial mechanical system with different boundary conditions. The first model represents the superstructure of the building with a fixed-end at the soil base level. In the second model, the superstructure is based on the substructure, which includes a pile foundation and a soil base with different physical and mechanical properties. The purpose of the study is a comparative numerical analysis of the stress-strain state of a large-span building with different boundary conditions. The numerical study revealed the influence of the structural features of the substructure of the building, as well as the physical and mechanical properties of the soil base on the stress-strain state of the long-span roof and the building as a whole. Numerical static analysis of spatial finite element models of a large-span building was carried out in the СAE class Femap NX Nastran software package. The results of the static analysis demonstrated a significant structural influence of the substructure of a large-span building on the characteristics of its stress-strain state. In the next article, it is proposed to conduct a modal analysis for these building models.

A comparative numerical analysis and environment assessment to examine hydrothermal behavior of two serpentine heatsink with water/silver Nano fluid applying two-phase mixture model

In the present study, the hydrothermal characteristics of two different a) serpentine (Conf. A), and b) double serpentine (Conf. B) heatsinks with water/silver Nano Fluid (NF) were studied. To this end, the Finite volume method was performed, and the governing equations were discretized based on the second upwind approach and solved numerically applying the Semi-Implicit Method for Pressure Linked Equations (SIMPLE) scheme. The results demonstrated that the thermal resistance (R) of Conf. A is lower than that of Conf. B at low Re numbers, and these two configurations have an identical R as Re increases to 2000. Also, the convective heat transfer in Conf. A is slightly higher than that in Conf. B and for Re=2000 both configurations have a same h value. Moreover, the increasing of nanoparticle concentration from 0% to 1% increases h by 12.55% and decreases the pressure drop (ΔP) by 4.25%. In addition, the CPU mean temperature of Conf. A is 0.8% and 0.1% lower than that of Conf. B for Res of 500 and 2000, respectively. On the other hand, ΔP in Conf. A is 74% higher than that in Conf. B. Besides, Conf. B exhibits a better temperature uniformity as compared to other configuration. The parameter of figure of merit was obtained as 1.47 to 1.52 at Res of 500 and 2000, respectively, which showed that Conf. B provides a higher hydrothermal performance over the other configuration.The environmental impact of the designed heat sink is equal to 0.5388.

Turbogenerator Electromagnetic Analysis with Changing Reactive Load

Comparative numerical analysis of electromagnetic processes in the end zone of powerful turbogenerators has been carried out at changes in reactive load from rated duty to underexcitation, as well as performance parameters of static overload that determine the stability of synchronous operation of turbogenerators in the power system. It was demonstrated that the representation of magnetic field sources and calculation results in the form of rotating waves allows simplifying and speeding up the solution of threedimensional electromagnetic problems in the turbogenerator end zone. Using a previously developed calculation method, the electromagnetic fields and processes in over- and underexcitation modes, in particular, peculiarities of shielding in turbogenerators are studied. It was established that the added losses and electrodynamic forces in underexcitation modes acting on the outermost core packages, pressure plate, and stator shield increased by 1.5–3.0 times, resulting in accelerated aging of the turbogenerator end zone. An appropriate margin shall be provided in the cooling system and the structural design of the turbogenerator end zone. Static overload capacity in nominal conditions is determined by the ratio of maximum power to rated power. An analytical functional relationship between static overload capacity and load conditions was established. It was demonstrated that when switching to the underexcitation mode while maintaining the active load due to a decrease in the excitation current and maximum power, the static overload factor decreases to unity, that there is virtually no static stability margin of the turbogenerator in this mode. Calculations were made for turbogenerators with a capacity of 200–1111 MVA. It is recommended to limit the operation of turbogenerators in underexcitation modes and to use specialized compensators more extensively.

A comparative numerical analysis of design variation plans for a shallow tunnel in very soft ground after a sudden accident

A severe accident of surrounding soil failure occurred during the construction of Zizhi Tunnel, a shallow tunnel in very soft ground using the shallow tunneling method in Hangzhou, China. We provide an in-depth comparison with careful evaluation of three design variation plans through 3D numerical analyses on the stress distribution inside the advance core, ground deformation, and soil arching over the tunnel crown. Consequently, the third support design scheme, i.e., soil reinforcement using sub-horizontal Metro Jet System (MJS) piles, is recommended as it leads to the smallest disturbance to the surrounding ground, and is the most favorable for the soil arching formation. We also find that the advance core’s stability is crucial for preventing the face failure and reducing the surface settlement. Finally, the effectiveness of world’s first successful example of applying sub-horizontal MJS piles to reinforce tunnel excavation in very soft soil is verified by the field monitoring data.

Workload balance-based dynamic two-sided matching decision-making approach for cloud manufacturing tasks and services under uncertain preferences

PurposeThis paper aims to develop a dynamic two-sided stable matching method based on preference information of the matching objects in uncertain environments, so as to solve the matching problem of cloud manufacturing tasks and services with load balancing.Design/methodology/approachFor dynamic two-sided matching, due to the complexity of social environment and the limitation of human cognition, hesitation and fuzziness always exist in the process of multi-criteria assessment. First, in order to obtain the accurate preference information of each matching object, uncertain linguistic variables, uncertain preference ordinal and incomplete complementary matrices are used to evaluate multi-criteria preference information. This process is undertaken by considering the probability of each possible matching pair. Second, the preference information at different times is integrated by using the time-series weight to obtain the comprehensive satisfaction degree matrices of the matching objects. Further, the load adjustment parameter is used to increase the satisfaction degree of the matching objects. Afterward, a dynamic two-sided stable matching optimization model is constructed by considering stable matching conditions. The model aims to maximize the satisfaction degree and minimizes the difference in the satisfaction degree of matching objects. The optimal stable matching results can be obtained by solving the optimization model. Finally, a numerical example and comparative analysis are presented to demonstrate the characteristics of the proposed method.FindingsUncertain linguistic variables, uncertain preference orders and incomplete complementary matrices are used to describe multi-criteria preference information of the matching objects in uncertain environments. A dynamic two-sided stable matching method is proposed, based on which a DTSMDM (dynamic two-sided matching decision-making) model of cloud manufacturing with load balancing can be constructed. The study proved that the authors can use the proposed method to obtain stable matching pairs and higher matching objective value through comparative analysis and the sensitivity analysis.Originality/valueA new method for the two-sided matching decision-making problem of cloud manufacturing with load balancing is proposed in this paper, which allows the matching objects to elicit language evaluation under uncertain environment more flexibly to implement dynamic two-sided matching based on preference information at different times. This method is suitable for dealing with a variety of TSMDM (two-sided matching decision-making) problems.

A comparatively numerical investigation on heat transfer behavior of different materials used for internal combustion engines

The aluminum and magnesium alloys are mostly used in the development of internal combustion engines. In the present investigation, an aluminum based composite material has been developed by utilizing the hybrid casting technique with the composition of Al + 7.5 wt.% Si3N4 + 5 wt.% MgO. Further, a comparative numerical analysis has been performed on the four-cylinder diesel internal combustion engine with the help of finite element analysis code Abaqus. The numerical investigation was performed and compared for the three materials Al + 7.5 wt.% Si3N4 + 5 wt.% MgO (Material 1), WE43A magnesium alloy (Material 2), and Al356 aluminum alloy (Material 3) based on temperature distribution and heat flux. The results revealed that the developed composite material (Material 1) shows a good temperature at the core of the four-cylinder diesel engine which supports the combustion process. Further, it shows the minimum temperature at the cylinder wall in both directions (along the length and width) which supports the cooling system. Further, Material 1 shows the lowest heat flux near the cylinder wall which is a more desirable characteristic for the internal combustion engine. Hence the developed material can replace Material 1 and Material 2 which are the alloys of aluminum and magnesium alloys.

Lamb waves in discrete homogeneous and heterogeneous systems: Dispersion properties, asymptotics and non-symmetric wave propagation

In this paper, we study Lamb waves propagating in a discrete strip, whose microstructure is represented by either a monatomic or a diatomic triangular lattice. In considering the in-plane vector problem, we derive an analytical solution for the dispersion relation of Lamb waves. Additionally, we investigate the main features of the eigenmodes of the system, which describe how the lattice strip vibrates at different frequencies. Further, we discuss how the dispersion properties depend on the number of the lattice’s rows and on the chosen boundary conditions. For heterogeneous systems, we focus the attention on the internal stop-band and on the flat bands appearing in the dispersion diagram. Different asymptotic models are employed to approximate the low-frequency behaviour of the lattice strip, starting from the classical Euler–Bernoulli beam. The effective behaviour of a lattice strip with dense microstructure is also investigated, and we present a comparative numerical analysis with the analogous continuum for which the classical Lamb wave problem is posed. The theory developed is exploited here to design a structured medium capable of manipulating wavemodes, and, through conversion and selection, generating uni-directional wave phenomena. We envisage that the present work can fill a gap in the research field related to the analytical study of dispersive waves in microstructured media, whose dynamic performance is influenced by the presence of multiple external boundaries.

A dynamically hybrid path planning for unmanned surface vehicles based on non-uniform Theta* and improved dynamic windows approach

This paper presents a dynamically hybrid path planning scheme incorporating the global guidance, real-time motion planning and collision-free maneuvering for Unmanned Surface Vehicles (USVs). To ensure safe navigation in narrow waters, the non-uniform costmaps with risk function is designed for global planning. Non-uniform Theta* (NT*) performs a reverse search from the goal node to establish the mapping relation containing the parent node and minimum path-cost of each cell. To prevent USV trapping into local minimum after avoiding the dynamic obstacles, the parent node is dynamically selected as the local target of improved dynamic window approach (IDWA), rather than tracing the sub-target fixed in global path as DWA does. In order to intensify navigation efficiency of the USV, the minimum path-cost from current cell to the goal is also implemented to the objective function of IDWA for evaluating the predicted trajectories. The proposed algorithms are validated by comparative numerical analysis and proven to work effectively.

Performance and Application of Geocell Reinforced Sand Embankment under Static and Cyclic Loading

As reinforcement material, geocells are widely used in various types of embankment reinforcement. A lot of practical experience shows that geocell reinforced embankment has good reinforcement effect, but the theoretical research lags behind the engineering practice, and the reinforcement mechanism under cyclic loading under various reinforcement conditions needs to be further studied. In this paper, the reasonable reinforcement condition of geocell reinforced embankment under static and cyclic loading is proposed by using a physical model and numerical simulation comparative analysis method. The research findings include: under cyclic loading, the inhibition effect of the number of reinforced layers on the vertical cumulative settlement is better than that under static loading, but the effect of two-layer reinforcement and three-layer reinforcement is relatively close, and both can reduce the vertical settlement by more than 40%. The inhibition effect of the increase of geocell height on the horizontal deformation of slope surface is better than that of the decrease of welding spacing under cyclic loading, and the reinforcement effect of the middle and upper part of embankment is better. Increasing the height of geocell and reducing the welding spacing can improve the limit bearing capacity of embankment, and the former is better. The optimal reinforcement condition of sandy soil embankment under cyclic loading obtained from the comparative analysis is case 3, that is, the reinforced layers is 2, the geocell height is 10 mm, and the welding distance is 50 mm.

Numerical Simulation and Comparative Analysis of Three Boil-Off Gas Reliquefaction Systems

Abstract In view of the problem that the boil-off gas (BOG) generated by small liquefied natural gas (LNG) ships affects the transportation safety, three BOG reliquefaction systems are improved, which are as follows: case 1: serial nitrogen expansion reliquefaction system (N2-BOG); case 2: single mixed refrigerant reliquefaction system (SMR-BOG); and case 3: propane precooled mixed refrigerant reliquefaction system (C3MR-BOG). The basic process is simulated in aspen plus and combined with the mathematical model built up in matlab where the three cycles are optimized with the specific power consumption (SPC) as the objective function. The results show that the SPC of three cases are 0.8021 kWh/kg (LNG), 0.4150 kWh/kg (LNG), and 0.5063 kWh/kg (LNG); the coefficient of performance (COP) of cases 1, 2, and 3 are 0.20, 0.39, and 0.30; the exergy efficiency of 36.56%, 70.66%, and 57.93% along with the total product cost of 89.00 $/h, 55.73 $/h, and 77.54 $/h are achieved in Cases 1–3, respectively. In addition, the overall exergy destruction of the cycles and each equipment are discussed, and the matching of the cold and heat sources of the multistream heat exchanger in the three systems is analyzed. In conclusion, under the condition that the BOG mass flowrate is 350 kg/h, the improved SMR-BOG has advantages on thermodynamic performance and economic analysis, which makes it a better choice.

Experimental and numerical comparative crashworthiness analysis of innovative renewable hybrid barrier with conventional roadside barriers

Guardrails are passive safety elements used in roadside safety. They are commonly manufactured as steel and concrete. There are also guardrail systems in which wood and steel materials are used together. This study investigated the crashworthiness performance of a newly developed F-shape type renewable hybrid barrier (RHB) system consisting of wood, steel and sand components. Commonly used steel guardrail and F-shape type concrete barrier were used for performance comparison. For this, a pendulum impactor has been set up. The impact performances of the aforementioned guardrails in the pendulum assembly were determined, then tests were carried out by modelling the pendulum system in the LS-DYNA environment for full-size crash testing and calibration. Calibration and validation were performed by comparing the Finite Element (FE) results with the pendulum results. Then, to determine the crashworthiness and safety of RHBs and compare them with steel and concrete barriers, full-size finite element models were created in the TB11 test standard specified in the European roadside safety standard - EN1317. As a result of the analysis, while providing the comfort of a concrete barrier after impact, RHBs perform close to the steel barrier in terms of safety. This study will be the first step before the prospective full-scale crash analysis.

A numerical comparative analysis between crank-Nicolson finite difference method and binomial model for European call option price

There are several kinds of numerical techniques for solving option valuation problems. In this article Binomial model (BM) and Crank-Nicolson finite difference (CNFD) approach are applied and compared with the Black-Scholes analytic solution (BSAS) to determine the best numerical method. It has been noticed that, for the valuation of European call (EC) options at various factors, the Binomial model (BM) is found to be more accurate than the Crank-Nicolson finite difference (CNFD) technique. In addition, for the impact of high volatility, the technique of Crank-Nicolson finite difference (CNFD) approaches quicker to Black-Scholes analytic solution (BSAS) than the Binomial model (BM). Furthermore, in comparison to the Binomial model (BM), CNFD method consumes more time to determine the option price in each time step.