Guided missiles are a key weapon in modern warfare, where designers aim to enhance their accuracy and lethality. In the conceptual design phase, the problem of missile trajectory tailoring to hit a specified target emerges. Nonetheless, focusing solely on this design goal may cause degradation in other design aspects such as structural integrity and flight control demands. Therefore, it is highly recommended to integrate flight, control, and structural aspects in the early phases of design. This study focuses on the conceptual phase of a guided surface-to-surface tactical missile trajectory toward a set of predefined targets with constraints. A comprehensive analysis is implemented to solve the trajectory optimization problem of a generic tactical missile. Based on a point-mass three-degree-of-freedom flight model, the optimal-control solver GPOPS is employed to solve this trajectory optimization problem. To ensure realistic and visible trajectory problem solutions, several physical constraints are considered, including minimum and maximum allowable dynamic pressure and maximum allowable rate for flight path angle. The control budget needed for each trajectory problem is discussed. Optimal trajectories ensuring maximum impact velocity via free and constrained flights are evaluated. Furthermore, trajectory problems that balance between minimum control budget and maximum lethality are analyzed.

Welded steel body components are commonly employed in special-purpose machine tools due to their high stiffness. However, this design approach typically results in low damping capacity. To enhance the dynamic performance of such structures, the use of polymer concrete as a filler material in closed profiles has been proposed. This paper presents the results of an experimental investigation on steel beams filled with polymer concrete. Three different polymer concrete mixtures were selected for testing. The study includes fatigue testing to evaluate whether long-term variable loading, representative of operational conditions, induces structural changes in the polymer concrete. The study analyzed the natural frequencies corresponding to the first three resonance modes, as well as the damping coefficients. Based on the measurement results, it was found that throughout the entire fatigue testing range, the variation in the sample's natural frequency ranged from 1.5 to 29.5\;Hz. In contrast, the damping coefficient varied between 0.023 and 0.161 for the tested sample. Dynamic parameters were analyzed, and the most effective indicator for assessing structural alterations is proposed by the author.

This paper presents the design of an optimal robust algorithm for performance control of an automotive electric power steering system. The proposed controller is formulated based on a Sliding Mode Control (SMC) framework. A Genetic Algorithm (GA) with six stages determines the sliding surface parameters of the control mechanism. The Lyapunov criterion evaluates the stability of the system. The novelty of this study lies in integrating the robustness of SMC with the optimization capability of the GA to automatically tune the sliding surface parameters. Unlike conventional SMC designs that rely on manual parameter adjustment, the proposed framework achieves fast convergence and reduced tracking error without complex gain tuning. Furthermore, it simplifies the controller structure and improves energy efficiency while mitigating the chattering phenomenon that typically affects SMC-based systems. The performance of the proposed controller is validated by numerical simulation. The computational results show that tracking errors are significantly reduced (only about 0.101% for v1 = 30 km/h and 0.132% for v2 = 60 km/h) compared to conventional PID control. Furthermore, power consumption is also significantly reduced. In addition, the influenceof the chattering phenomenon is largely eliminated. This combination can be applied to the control of automotive mechatronic systems.

This study investigates the flow and heat transfer characteristics of copper (Cu) and silver (Ag) nanofluids over a permeable, moving flat plate embedded in a porous medium under the influence of a uniform magnetic field. Key effects such as thermal radiation, viscous dissipation, nanoparticle volume fraction, and suction/injection are incorporated into the model. The governing partial differential equations are reduced to ordinary differential equations using similarity transformations and solved numerically via the Runge-Kutta fourth-order method with a shooting technique. Results reveal that Ag-water nanofluid exhibits a higher temperature profile, whereas Cu-water shows greater skin friction and heat transfer rates. Velocity decreases with increasing magnetic field strength, porosity, volume fraction, and suction/injection parameters. Thermal boundary layer thickness increases with magnetic and porosity parameters but decreases with stronger suction. The Nusselt number increases with nanoparticle concentration, and temperature rises with higher viscous dissipation but decreases with thermal radiation.

Tool-path smoothing is essential for ensuring continuous motion at transition corners between linear segments, since kinematic discontinuities degrade both machining efficiency and surface quality. Most existing spline-based methods achieve only G2 or C2 continuity and therefore produce discontinuous jerk, which can excite high-order structural resonances. Achieving true C3 continuity remains challenging, particularly because synchronizing tool-tip position and orientation is complicated by the nonlinear relationship between arc length and spline parameterization. This study presents an analytical Catmull–Rom (CR) spline–based method for C3-continuous tool-path smoothing in five-axis CNC milling. Transition corners are replaced by adjustable Catmull–Rom (ACR) splines, whose control points and tuning parameters are designed or optimized to constrain the deviation from the original path. The remaining linear segments are also substituted with ACR splines to enforce position–orientation synchronization, with control points that can be chosen analytically to guarantee zero synchronization error. The proposed method is fully analytical and non-iterative. Numerical simulations demonstrate that the generated tool paths satisfy prescribed geometric tolerances, produce smooth and continuous jerk profiles, and achieve exact synchronization between tool-tip position and orientation.

The Inverted Pendulum Cart (IPC) system is a significant challenge in control theory, is used as a benchmark for evaluating advanced actuator control techniques, and has critical applications in robotics and autonomous systems. This paper proposes a new control strategy based on a Hierarchical Non-Singular Fast Terminal Sliding Mode (HNFTSM) controller technique enhanced by an Extreme Learning Machine (ELM) neural network to achieve system stability. HNFTSM provides finite time convergence and resistance to disturbances and uncertainty, while the ELM contributes to estimating these disturbances to improve performance. The stability of this strategy is proven using the Lyapunov stability theory, which ensures that all system states reach the desired equilibrium in finite time. Furthermore, the proposed hierarchical control scheme guarantees finite-time convergence of all closed loop IPC states under bounded uncertainties. A comprehensive comparative analysis is conducted against other advanced control techniques, including HSMC, HNTSM, ELM-HNTSM, and conventional NFTSM controllers. Simulation results show that the proposed approach outperforms other methods in tracking accuracy, convergence speed, singularity avoidance, and chattering reduction, which enhances the effectiveness of system control and makes it promising for practical applications.

This study presents a nonlinear dynamic model of a flexible overhead crane operating in a vertical plane. The model simultaneously considers the flexural deformation of the main girder, the axial elongation of the hoisting cable, and the effects of internal damping. The equations of motion are formulated as a system of nonlinear ordinary differential equations (ODEs), allowing efficient simulation of the system's dynamic response, vibration behavior and stability characteristics. Numerical analyses are conducted for both undamped and damped cases. The results show that the elastic deformation of the cable is the primary source of beam vibration, while the payload sway also contributes to the overall oscillation. Including cable elasticity slightly increases the maximum beam deflection but significantly amplifies elastic oscillations. When damping is introduced, both cable and beam oscillations are reduced, and can be reduced to static deformation with increasing damping. The study provides a compact yet accurate modeling framework and offers useful insights for the integrated control of elastic and sway vibrations in flexible overhead cranes.

The modern battlefield requires highly accurate missiles, which has led to the modification of unguided missiles into guided versions. This paper presents the process of adapting an unguided missile with a range of 40 km into a guided version using a canard control system. A key aspect of the upgrade was the development of a control system that allows the trajectory to be corrected after crossing the apex of the flight path, particularly during the descent phase. This paper discusses the design details and application of a two-channel control system (pitch and yaw) in which the control signals are synchronized with the speed of the projectile. Mathematical modelling and numerical simulations have shown that, with appropriate control parameters, a zero mean control force can be achieved, leading to trajectory stabilization and minimized aiming errors. The proposed solution provides a basis for further research and dynamic field tests and can contribute to the development of precision guidance technology for surface-to-surface missiles.