Fractal and Fractional最新文献_第9页

The Influence of Environmental Temperature on the Passive Oxidation Process in the C/SiC Composite 环境温度对 C/SiC 复合材料被动氧化过程的影响

Fractal and Fractional Pub Date : 2024-03-27 DOI: 10.3390/fractalfract8040192

Qingyong Zhu, Haixin Jie, Shun Lu, Zhihui Li

{"title":"The Influence of Environmental Temperature on the Passive Oxidation Process in the C/SiC Composite","authors":"Qingyong Zhu, Haixin Jie, Shun Lu, Zhihui Li","doi":"10.3390/fractalfract8040192","DOIUrl":"https://doi.org/10.3390/fractalfract8040192","url":null,"abstract":"The C/SiC composite plays a crucial role in providing thermal protection for hypersonic vehicles. The SiO2 oxide layer formed via passive oxidation during ablation constitutes a typical porous medium with self-similarity. Given its significant impact on the thermal protection of the material, accurately predicting the variation in the SiO2 oxide layer thickness is of paramount importance. The growth of the oxide layer impedes the diffusion of oxygen within the material. This study considered microstructural parameters of the oxide layer based on high-temperature gas oxidation tests of the C/SiC composite. Fractal theory was utilized to construct a fractal diffusion-reaction kinetics model describing oxygen diffusion within the oxide layer and the evolution of the oxide layer under varying environmental conditions. The finding demonstrated that the existence of the oxide layer significantly influences the passive oxidation of the composite. This study underscored the significance of predicting the impact of environmental parameters on passive oxidation in the practical application of the C/SiC composite and the study result offers a valuable reference for evaluating the thermal resistance of the C/SiC composite.","PeriodicalId":510138,"journal":{"name":"Fractal and Fractional","volume":"15 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140374286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Bifurcation Exploration and Controller Design in a Fractional Oxygen–Plankton Model with Delay 带延迟的分数氧浮游生物模型中的分岔探索和控制器设计

Fractal and Fractional Pub Date : 2024-03-27 DOI: 10.3390/fractalfract8040190

Yunzhang Zhang, Changjin Xu

引用次数: 0

On the Solvability of a Singular Time Fractional Parabolic Equation with Non Classical Boundary Conditions 论具有非经典边界条件的奇异时间分式抛物方程的可解性

Fractal and Fractional Pub Date : 2024-03-26 DOI: 10.3390/fractalfract8040189

Eman Alhazzani, S. Mesloub, H. E. Gadain

引用次数: 0

The Sign-Changing Solution for Fractional (p,q)-Laplacian Problems Involving Supercritical Exponent 涉及超临界指数的分数（p,q）-拉普拉卡问题的符号变化解法

Fractal and Fractional Pub Date : 2024-03-25 DOI: 10.3390/fractalfract8040186

Jianwen Zhou, Chengwen Gong, Wenbo Wang

引用次数: 0

Adaptive Terminal Sliding-Mode Synchronization Control with Chattering Elimination for a Fractional-Order Chaotic System 针对分数阶混沌系统的自适应终端滑模同步控制与颤振消除

Fractal and Fractional Pub Date : 2024-03-25 DOI: 10.3390/fractalfract8040188

Chenhui Wang

引用次数: 0

Investigation of the Robust Fractional Order Control Approach Associated with the Online Analytic Unity Magnitude Shaper: The Case of Wind Energy Systems 与在线分析统一振幅整形器相关的稳健分数阶控制方法研究：风能系统案例

Fractal and Fractional Pub Date : 2024-03-25 DOI: 10.3390/fractalfract8040187

A. Mseddi, Ahmed Abid, O. Naifar, Mohamed Rhaima, A. Ben Makhlouf, Lassaad Mchiri

{"title":"Investigation of the Robust Fractional Order Control Approach Associated with the Online Analytic Unity Magnitude Shaper: The Case of Wind Energy Systems","authors":"A. Mseddi, Ahmed Abid, O. Naifar, Mohamed Rhaima, A. Ben Makhlouf, Lassaad Mchiri","doi":"10.3390/fractalfract8040187","DOIUrl":"https://doi.org/10.3390/fractalfract8040187","url":null,"abstract":"This paper investigates the development of a novel analytic approach for computing Unity Magnitude (UM) shapers that deviates from established numerical methodologies. The experimental validation on a test bench confirms the practicality and benefits of the suggested UM shaper technique. The study extends the use of UM shapers to improve the control of wind conversion systems (WCSs), particularly those including hybrid excitation synchronous generators (HESGs), demonstrating their adaptability and versatility. Experimental validation guarantees real-world application, confirming the suggested UM shapers’ trustworthiness. Strict management is still required to assure the system’s efficiency and dependability. In reality, the dynamic equations of a turbine, as well as those of an HESG, are substantially nonlinear; most system parameters are very uncertain; and, finally, a WCS is always impacted by disturbance sources such as load variations, harmonics, and mechanical vibrations. Robust control measures must be used to overcome these issues. A CRONE controller (Robust Fractional Order Control) of the second generation is created. A comparative study performed on the Simulink platform reveals substantial gains brought about by UM shapers in real-world circumstances. The study demonstrates the effectiveness of UM-shaped inputs in mechanical stabilization and Maximum Power Point Tracking (MPPT), emphasizing both theoretical soundness and practical advantages. The analytic equations for UM shapers in undamped and damped systems, offered together with a real-time algorithm, contribute to the optimization of wind conversion systems.","PeriodicalId":510138,"journal":{"name":"Fractal and Fractional","volume":" 44","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140385229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Novel Hybrid Crossover Dynamics of Monkeypox Disease Mathematical Model with Time Delay: Numerical Treatments 带时间延迟的新型混合交叉动态猴痘病数学模型：数值处理

Fractal and Fractional Pub Date : 2024-03-24 DOI: 10.3390/fractalfract8040185

N. Sweilam, S. Al-Mekhlafi, Saleh M. Hassan, Nehaya R. Alsenaideh, A. E. Radwan

引用次数: 0

Remaining Useful Life Prediction of Roller Bearings Based on Fractional Brownian Motion 基于分数布朗运动的滚子轴承剩余使用寿命预测

Fractal and Fractional Pub Date : 2024-03-23 DOI: 10.3390/fractalfract8040183

Wanqing Song, Mingdeng Zhong, Minjie Yang, Deyu Qi, Simone Spadini, Piercarlo Cattani, Francesco Villecco

引用次数: 0

An Efficient Numerical Scheme for Fractional Order Mathematical Model of Cytosolic Calcium Ion in Astrocytes 星形胶质细胞胞质钙离子分数阶数学模型的高效数值方案

Fractal and Fractional Pub Date : 2024-03-23 DOI: 10.3390/fractalfract8040184

Devendra Kumar, Hunney Nama, Jagdev Singh, Jitendra Kumar

引用次数: 0

Statistical Study of the Bias and Precision for Six Estimation Methods for the Fractal Dimension of Randomly Rough Surfaces 随机粗糙表面分形维度六种估算方法的偏差和精度统计研究

Fractal and Fractional Pub Date : 2024-03-07 DOI: 10.3390/fractalfract8030152

Jorge Luis Flores Alarcón, C. G. Figueroa, V. H. Jacobo, Fernando Velázquez Villegas, R. Schouwenaars

{"title":"Statistical Study of the Bias and Precision for Six Estimation Methods for the Fractal Dimension of Randomly Rough Surfaces","authors":"Jorge Luis Flores Alarcón, C. G. Figueroa, V. H. Jacobo, Fernando Velázquez Villegas, R. Schouwenaars","doi":"10.3390/fractalfract8030152","DOIUrl":"https://doi.org/10.3390/fractalfract8030152","url":null,"abstract":"The simulation and characterisation of randomly rough surfaces is an important topic in surface science, tribology, geo- and planetary sciences, image analysis and optics. Extensions to general random processes with two continuous variables are straightforward. Several surface generation algorithms are available, and preference for one or another method often depends on the specific scientific field. The same holds for the methods to estimate the fractal dimension D. This work analyses six algorithms for the determination of D as a function of the size of the domain, variance, and the input value for D, using surfaces generated by Fourier filtering techniques and the random midpoint displacement algorithm. Several of the methods to determine fractal dimension are needlessly complex and severely biased, whereas simple and computationally efficient methods produce better results. A fine-tuned analysis of the power spectral density is very precise and shows how the different surface generation algorithms deviate from ideal fractal behaviour. For large datasets defined on equidistant two-dimensional grids, it is clearly the most sensitive and precise method to determine fractal dimension.","PeriodicalId":510138,"journal":{"name":"Fractal and Fractional","volume":"69 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140077794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0