Vol. 9, No. 3 (2025): Regular Issue

The complex structural characteristics of the automobile engine cylinder head and the harsh working environment make the thermal-mechanical fatigue damage of the cylinder head particularly prominent. In this paper, the cylinder head of automobile engine is taken as the research object, and the finite element model of cylinder head-gasket-cylinder block is established based on workbench software. The fluid dynamics analysis (CFD) and multi-field coupling analysis are carried out. The influence of bolt preload, gas pressure and temperature field load on cylinder head stress is compared and analyzed, and the fatigue life of cylinder head under thermal load-mechanical load coupling is evaluated. The results show that the temperature field load has the most significant influence on the cylinder head stress, accounting for 50% $\mathrm{\sim}$ 80% of the total load. Under the thermo-mechanical coupling, the temperature gradient between the exhaust zone and the intake zone is high, the safety factor is low, and fatigue failure is prone to occur.

Retraction Notice

Retraction: “An Investigation of the Dynamic Properties of an Active Discrete Memristor Model Incorporating an Exponential Memristance”

The Editor retracts the above article, published in Journal of Vibration Testing and System Dynamics, 9(3), 221–231 (2025), https://doi.org/10.5890/JVTSD.2025.09.002.

Following an editorial review, several references cited in the article could not be verified as existing publications. These references are material to the article’s discussion of prior work, and their unverifiable status undermines confidence in its scholarly foundation. The Editor has therefore determined that a correction would not adequately address these concerns.

This retraction is issued to ensure the accuracy and reliability of the published record.

Original Abstract

In 1971, Chua discovered the memristor, which is considered the fourth fundamental electrical component alongside resistance, capacitance, and inductance. In recent years, numerous models of discrete memristors have been constructed since the formal proposal of the subject. However, there is rare discussion about the active discrete memristor models. This study combines a general map for constructing memristive maps with the modulo function and an exponential memristance, which produces a locally active discrete memristor model. Nonlinear tools, including bifurcation and continuation diagrams, Lyapunov spectrum diagrams, and phase portraits, were employed to investigate the system's dynamical behavior. The results revealed various intriguing phenomena related to chaos theory, including periodic or chaotic orbits, the mechanism of period doubling route to chaos, crisis phenomena, as well as coexisting attractors.

In this paper, complex projective synchronization (CPS) is discussed to understand the different aspects of chaotic systems. Firstly, CPS for integer-order and fractional-order chaotic systems is investigated. Later, in case of CPS the influence of time-delay on chaotic systems is broadly investigated. Control functions are derived using the adaptive control technique in all circumstances. The behavior and various dynamical features of complex dynamical systems are theoretically investigated. Lastly, numerical results agreed with the theoretical hypothesis.

The primary intent of this work is to explore the radiation effects of an unstable MHD Williamson bio-fluid (Blood) over a wedge that interacts with thermophoresis diffusion and Brownian motion. Apply similarity transformation to convert the essential prerequisites of partial differential equations (PDEs) into ordinary differential equations (ODEs). The results of these ODEs have a significant impact on the BVP4C approach from the MATLAB package computational structures. The graphs and tabular data provided the various values for physical quantities found and discussed in detail. Furthermore, to estimate Machine Learning (ML) under Multiple Linear Regression (MLR) and validate Linear Support Vector Machine (SVM) to anticipate the physical quantities for current numerical discoveries. Drug delivery systems for therapeutic and diagnostic approaches for cancer treatment are possible advantages of these results. An additional benefit is that the outcomes showed acceptable congruence with the tangible findings of recent research and enlargements for future investigators.

This research aims to enhance the efficiency of a valveless piezoelectric miniature pump through the implementation of feedback control. Finite element analysis reveals that the motion of the structure impacts pumping efficiency. Using plant identification, a linear finite-element model of the miniature pump is reduced to a single-mode model with a single input. To increase the pumping efficiency, a closed-loop tracking control based on a nonlinear control technique, i.e. exact feedback linearization, is employed. The closed-loop miniature pump outperforms the open-loop miniature pump in terms of settling time and the pressure load existence at an outlet of the miniature pump, also improving efficiency by tracking a reference signal with two frequencies.

This study examines the synchronization between distributed-order chaotic systems. The primary goal is to construct control functions to synchronize the distributed-order drive and response systems by implementing Laplace transform. In addition, the fundamental characteristics of chaotic systems are examined. We describe a strategy for introducing generalized synchronization between distributed-order chaotic systems. We also discuss inverse generalized synchronization between chaotic systems with different dimensions. Ultimately, numerical simulations confirm the accuracy of the acquired outcomes.

Artificial cardiac assist devices are effective devices for the treatment of heart failure. In this paper, two semi-open impeller centrifugal blood pumps with the characteristics of full hydrodynamic suspension are optimized based on fluid dynamics. The dynamic pressure coupling effects between the impeller and the blood are crucial for the safe installation and circulation of the blood pump. Numerical simulations of the blood pump are conducted using computational fluid dynamics (CFD) methods, which include unstructured mesh, ${k} $--$\varepsilon$ model, and coupled algorithms, to investigate the influence of various parameters such as the number of blades, outlet angle, wrap angle, blade curvature, and structural elements like guide column and splitter blades on the performance of the blood pump. The results show that both types of impellers perform optimally with 10 blades, equipped with guide vanes and splitter blades. For the favorable parameter design model, it is recommended to select an outlet angle of 60$^\circ$ and a wrap angle of 120$^\circ$, while for the Bezier curve design model, it is suggested to choose an outlet angle of 30$^\circ$ and a blade curvature angle of 90$^\circ$