Abstract This research presents a control-oriented nonlinear mathematical model and control framework for the short take-off and vertical landing (STOVL) dynamics of an F-35B aircraft, specifically focusing on the critical phase of an inclined landing trajectory. The aircraft is characterised as a six-degree-of-freedom (6-DOF) rigid body within the North-East-Down (NED) inertial frame, explicitly incorporating cross-coupling effects in the inertia tensor. The integrated modelling architecture encompasses a multi-nozzle propulsion system comprising a lift fan, a rear swivel nozzle with thrust vectoring capabilities, and dual-wing roll posts and a control-oriented aerodynamic model based on stability derivatives and dynamic pressure scaling. A significant contribution of this study is the extension of the rigid-body equations with a three-point landing gear subsystem that accounts for independent unsprung masses, linear suspension compliance and unilateral tire contact constraints, enabling a realistic simulation of the transition from jet-borne flight-to-ground interaction. To stabilise the inherently unstable STOVL envelope, a linear quadratic regulator (LQR) is synthesised via numerical linearisation of the nonlinear plant. Simulation results demonstrate the controller’s effectiveness in maintaining precise trajectory tracking and attitude regulation, successfully managing the complex force interactions between the propulsion system and the mechanical suspension during touchdown on a landing surface.

This study presents a novel energy harvesting system based on a perpendicular magnetic coupling of dual cantilever beams, designed to achieve direction-independent excitation under ambient airflow. In contrast to conventional systems with single-axis response, the proposed configuration enables magnetic force transmission from the primary beam to the secondary beam regardless of flow direction, allowing simultaneous energy extraction from both beams. A comprehensive nonlinear dynamic model is developed using Lagrangian mechanics, incorporating piezoelectric coupling, magnetic interaction, and harmonic aerodynamic excitation. The model is supported by finite element analysis to demonstrate the feasibility of integrating the system into a small-scale wind turbine application. A proposed prototype is constructed, and detailed experimental study is conducted. The harvested energy is rectified and successfully used to power low-power electronic devices such as LEDs and temperature sensors. The outcomes confirm the practicality of the proposed dual-beam configuration for self-powered systems operating under variable excitation conditions.

This study presents a comprehensive experimental investigation into the influence of bluff body geometry and spatial arrangement on flow-induced vibrations and their application for piezoelectric energy harvesting. Wind tunnel tests were performed on both single and tandem bluff body configurations, where unsteady aerodynamic forces excite a flexible cantilever beam integrated with a piezoelectric transducer. Utilizing a full factorial Design of Experiments (DOE) approach, the effects of bluff body shape-from sharp-edged cubes to fully rounded spheres-and longitudinal spacing on vibration amplitude and electrical output were systematically analysed. Results reveal that rounded geometries, particularly the spherical bluff body (C6), positioned at an optimal tandem spacing of 1.25 times the characteristic diameter (1.25D) upstream of the flexible beam, generate the highest root mean square (RMS) displacement and voltage output, reaching up to 25.12 V RMS. Statistical analyses quantify the significant contributions of both geometric configuration and spacing distance to the dynamic and electrical responses, highlighting the critical interplay between wake dynamics and structural vibrations. These findings offer practical insights for optimizing flow-induced energy harvesting systems, advancing the development of self-powered devices for applications in environmental monitoring and fluid-structure interaction-based technologies. This study, by integrating experimental validation with energy harvesting assessment and systematic analysis, aims to deliver a more holistic and practically relevant contribution.

Dinamik titreşim emiciler mekanik sistemlerde titreşimleri ortadan kaldırmak veya daha düşük bir seviyeye getirmek için kullanılan pasif titreşim kontrol cihazlarıdır. Titreşim mühendislik uygulamalarında genellikle istenmeyen durum olarak karşımıza çıkmaktadır. Bir yapının ya da makinenin performansı ve dayanıklılığı üzerine doğrudan etkisi olan mekanik titreşimlerin aktif ya da pasif yöntemler ile bastırılması gerekmektedir. Dinamik titreşim emici cihazlar, titreşen bir yapının üzerine eklenerek asıl yapı üzerindeki titreşimleri sönümleler. Eklenen cihazın doğal frekansı titreşen asıl yapının doğal frekansı yakınlarında olacak şekilde seçilmektedir. Asıl sistemin üzerindeki titreşimler bastırılarak eklenen yeni kütlenin üzerine aktarılmış olur. Burada ayrıca sistemin serbestlik derecesi de eklenen yapı sayesinde arttırılmaktadır. Bu çalışmada eklenen kütlenin maruz kaldığı mekanik titreşimlerin faydalı enerjiye dönüşmesi adına bir enerji hasadı uygulaması gerçekleştirilmiştir. Deneysel olarak kurulan bir dinamik titreşim emici düzeneğinde elektromanyetik enerji hasadı yöntemi sunulmaktadır. Sistemde eklenen kütlede oluşan mekanik titreşimler ile indüklenen bir bobin üzerinden sabit mıknatıs yapısı yardımı ile gerilim üretimi gerçekleştirilmiştir. Doğal frekansı 3.58 [Hz] olarak tespit edilen sisteme asıl sisteme kendi frekansına yakın olacak şekilde (3.60 [Hz]) ikincil bir sistem eklenerek deneysel çalışmalar gerçekleştirilmiştir. Deneysel çalışmalar sonucunda rezonans frekansında tahrik edilen sistemin üzerindeki titreşimin dinamik titreşim emici yardımı ile bastırıldığı ve bu işlem sırasında eklenen kütle üzerinde oluşan titreşimlerinde faydalı enerjiye dönüştürme adına enerji hasadı uygulamasının gerçekleştirildiği gösterilmiştir.

This study focuses on vertical take-off and landing (VTOL) unmanned aircraft, examining the impact of air-launched missile releases on the system. The release process not only disrupts the system's symmetric structure but also alters its mass and inertia parameters. To address these challenges, the study introduces a model to analyze the effects of missile releases and incorporates a wind turbulence model to evaluate aircraft performance under various scenarios. The study focusses on understanding the impact of missile release on UAV performance, particularly under realistic turbulence conditions that are critical for VTOL operations.

Flow‐induced vibrations are common occurrences in various fluid–solid interaction systems existing in nature. One way to transform this vibrational mechanical energy into a usable form is through energy harvesters. This study examines the performance of a piezoelectric energy harvester, where mechanical oscillations result from the fluttering flags made of various fabrics. Flags, made of commonly encountered fabrics, are attached to a cantilever beam inside a wind tunnel with a 30 × 30 cm test section, allowing the airflow to be adjusted between 0 and 10 m s−1. The alpaca flag, with dimensions corresponding to an aspect ratio of 2, can produce meaningful electricity even at a wind speed as low as ≈3.8 m s−1. As the wind speed increases, the fluttering frequency of this flag configuration becomes 10.9 Hz at a wind speed of 5 m s−1, coinciding with the natural frequency of the first mode shape. In this specific arrangement, the structural deformation of the piezoelectric patch on the beam surface is maximized, allowing the harvester system to produce a root mean square voltage of 5 V with a relatively high maximum power of 98 μW.

Purpose In today’s technology, the significance of unmanned aerial vehicles is steadily increasing. Many unmanned aerial vehicles design, especially those used for military purposes, have achieved autonomy from human operators. Undoubtedly, one of the most crucial features of these aircraft is their vertical take-off and landing (VTOL) capability. Inspired by quadrotor methodology, this paper aims to conduct, a modeling of an aircraft with VTOL capabilities. Design/methodology/approach The impact of releasing air-launched missiles, considered as the useful payload carried during the flight of the aircraft, has been taken into account in this modeling. The release of air-launched missiles disrupts both the symmetric structure of the system and alters the mass and inertia parameters. Simulations were conducted to investigate scenarios involving the simultaneous release of all air-launched missiles and their release at different times. Findings The investigation focused on determining how quickly an aircraft, aiming to consecutively hit targets, can return to its desired trajectory. The time interval between the consecutive releases of two air-launched missiles has been identified. Originality/value It is crucial for a VTOL-capable aircraft to possess a unique modeling structure to examine its capability of releasing air-launched missiles in various scenarios. This entails understanding not only the aircraft’s VTOL functionality but also its ability to effectively release missiles in different operational conditions.

In this study, hybrid energy harvesting based on electromagnetic induction (EM) and piezoelectric transduction (PZT) is experimentally investigated under different conditions of flow-induced vibrations. The energy harvesting performance of the system is examined when the electromagnetic and piezoelectric mechanisms are used both separately and simultaneously. In this regard, firstly, only electromagnetic induction harvesting structure is attached to a beam, and time-dependent voltage and displacement are experimentally investigated. Then, PZT has adhered to the beam, and voltage outputs are measured in both the PZT and EM circuits. The third scenario is based on removing the electromagnetic harvesting structure and only the piezoelectric energy harvesting performance is studied. The mentioned cases are investigated under different excitation circumstances, that is, distinct bluff-body geometries and flow velocities. While the square bluff-body geometry is connected to the structure, both PZT and EM harvested power are determined by considering different electrical load resistances. It is mainly revealed that the total energy amount is higher in the hybrid configuration. After determining the hybrid structure is the most effective, elements with different splitters geometry are attached to the bluff-body geometry of the harvesting structure. Finally, the vibration enhancement potential of these new types of splitters on the harvesting structure is experimentally investigated. For the solo electromagnetic harvester, the maximum power is obtained at an external load resistance value of 10 kΩ, while for the solo PZT harvester, the maximum power is observed at the resistance value of 330 kΩ. Among the three types of splitter geometries examined, the highest voltage was obtained from type-1 as 14.168 V.

This study parametrically investigates the efficiency of an integrated energy harvesting system that consists of a piezoelectric patch attached to a cantilever beam and V‐shape bluff bodies with various apical angles. V‐shape bluff bodies are connected to a cantilever beam with a revolute joint that represents a two degrees‐of‐freedom configuration. The mechanical energy of the galloping and fluttering motions, resulting from the vortex shedding that appears downstream of the bluff bodies, is converted into electricity by means of a piezoelectric patch. The apical angle of the V‐shape geometries, that varies between 0° and 180°, is the main parameter where the generated voltages and the related power curves are the major results for the evaluation of the efficiency of this harvesting system. Based on the experimental examinations, the maximum output power of 0.295 mW is produced at a wind speed of 10 m s −1 for the apical angle of 180° and the electrical resistance of 230 kΩ. Moreover, the proposed energy harvester system can still produce usable output power for the apical angles ranges from 0° to 20° and from 170° to 180°.

-In this study, the design and analysis of multi-layer fully pitched winding switched reluctance motor (MFP-SRM) for general use (submersible pump, electric vehicles, etc.) have been performed. It is seen that the multi-layer switched reluctance motor (SRM) has higher output power when compared to the single-layer SRM. In multi-layer SRM, the motors in the layers are electromagnetically independent of each other although they are identically the same motors with the same characteristics in terms of performance and geometry. Each layer of the MFP-SRM which is designed in this study consists of a 6/4 pole fully pitched SRM (FP-SRM) and these motors are magnetically independent of each other. In the MFP-SRM, which is designed as a double layer, there is a 15 degrees phase difference between the rotor position angles and torque profile curves of each layer. With the phase difference that changes depending on the number of layers, each layer contributes to the total torque production of the profile, ensuring a smooth profile. According to the results of the 3D FEM analysis, it is seen that the proposed multi-layer motor structure has high starting torque and low torque ripple properties. In the analysis carried out in the range of 3-15 Amperes, the torque ripple of the traditional FP-SRM varies between 31.99% and 38.19%, while the torque ripple of the proposed MFP-SRM only varies between 3.23% and 7.11%.

In this article, a linear motor launcher system equipped with superconducting magnetic bearings has been constructed and tested under various conditions. The guide rail of the launcher features permanent magnets that support superconducting levitation and interaction between square prism-shaped bulk superconductors on various surfaces. This results in increased stiffness of a single superconductor along any given axis and comprehensive support of lateral forces. The article investigates the use of a superconducting magnetic bearing in a linear launcher system as a novel approach to a multisurface levitation structure. The experimental system integrates the high-temperature superconductor bulk material-based carriage system and an open cryostat structure. The carriage system levitates on the permanent magnet rail by moving it using an integrated dc linear motor. The article examines the levitation force relationship and performance of the system under different selected speeds and acceleration profiles. The design of the system allows for an adjustable slope of the permanent magnet rail, demonstrating the potential for use as a linear launcher pad. In addition, the proposed system has the potential for application in larger systems, such as maglev vehicles.

In this study, anomalous geometries were examined computationally and experimentally in terms of their aerodynamic performance as energy harvesters. The main motivation of this study is that most of these geometries, discussed in the present study, have not yet been previously considered as energy harvesters in literature. Some well-known geometries alongside these anomalous models were also investigated for comparison in this current study. The examination was conducted by means of the computational and experimental fluid dynamics approaches where the flow around these different models was analyzed in detail to shed light on the crucial aspects encountered during the flow separation over these various geometries. By this means, the lift coefficients of the investigated harvester geometries were considered as the essential parameter for time-dependent analyses in the numerical simulations since this parameter is the main reason for the flow-induced vibrations. Moreover, experimentally obtained voltages and power curves were compared for different geometries. Based on the root mean square values of the numerical lift coefficients, it was found that the best aerodynamically beneficial model is Model-7 (equal-length 3-tines fork shape) and the worst model is Model-5 (perpendicular plane). Velocity vectors and pressure distributions around these best and worst models were also provided to reveal the main differences in flow structures that may lead to a better design of energy harvester geometry for further studies.

A hybrid energy harvesting system has been presented in this study by vibrating a beam element with an electromagnetic actuator. With the structure proposed in this article, two different types of energy harvesting concepts were provided with the piezoelectric patch attached to the fixed end of the cantilever beam and the electromagnetic device connected to the free end of the cantilever beam. Generally, in electromagnetic energy harvesting systems, the electromagnetic device is fixed from one end to the ground. The effects of vibration of this fixed surface on energy harvest are being neglected. Electromagnetic devices that provide energy harvesting and vibrate the beam element are of identical structure in the proposed hybrid system. Both devices are mounted at the same point of the beam to face each other. While one of these electromagnetic devices is fixed onto the ground, the other one is assembled to the main beam with a secondary parallel beam element. Therefore, the electromagnetic device that harvests energy or vibrates the beam element can be changed so that it can be either on the lower or upper side of the main beam element. With this designed structure, the behavior of electromagnetic energy harvesting elements and vibration actuators placed on the non-rigid ground has been investigated. Unlike conventional energy harvesting methods, the concept of displacement transmissibility has been discussed in this study. Experimental studies have performed the dynamic conditions to obtain optimum energy harvest in the proposed harvesting system for different frequency inputs. Experimental results revealed the effect of vibrations originating from the non-rigid ground on energy harvesting. It has been observed that the electromagnetic energy harvesting device connected to the non-rigid ground increases the amount of energy collected.

Many structural systems, such as wind turbines, are exposed to high levels of stress during operation. This is mainly because of the flow-induced vibrations caused by the wind load encountered in every tall structure. Preventing the flow-induced vibration has been an important research area. In this study, an active electromagnetic mass damper system was used to eliminate the vibrations. The position of the stabilizer mass in the active electromagnetic mass damper system was determined according to the displacement information read on the system without using any spring element, unlike any conventional system. The proposed system in this study has a structure that can be implemented as a vibration suppressor in many intelligent structural systems. Two opposing electromagnets were used to determine the instant displacement of the stabilizer mass. The control currents to be given to these electromagnets are determined by using an adaptive backstepping control design. The adaptive controller algorithm can predict the wind load used in the controller design without prior knowledge of the actual wind load. It was observed that the designed active electromagnetic mass damper structure is successful in suppressing system vibrations. As a result, the proposed active electromagnetic mass damper system has been shown to be suitable for structural systems in flow-induced vibration damping.

In this study, the active vibration control system design of a composite beam with three different lamination angles under forced vibration was investigated. The produced composite beam lamination angles have been selected as {0°, 90°, 0°, 90°}s, {− 30°, 60°, − 30°, 60°}s and {− 45°, 45°, − 45°, 45°}s for investigating the vibration characteristic. Different types of bluff-body geometries were attached to the free end of the cantilever composite beams. In this way, the composite beam's vibration amplitudes have more fluctuated with the help of bluff body geometries. Bluff body structures are generally preferred in energy harvesting applications by increasing the vibration in beams. The fact that this structure, which increases the vibration amplitude, is handled in an active vibration control mechanism adds a different novelty to the subject. Flow-induced vibrations were obtained for a particular period by applying air load on it. Two different geometries of bluff bodies were placed in a freestream airflow at a constant speed to trigger and enhance the vibration of the composite beam. The front surface areas of two different bluff bodies exposed to air load are identical. Therefore, the difference in the vibrations characteristics was only affected by the geometrical differences in the lateral areas of the bluff bodies. To demonstrate this situation, the airfoil efficiency was investigated for the bluff body geometries. A piezoelectric patch is attached to the surface of the composite beam, and the vibration control is acquired utilizing the PID control design. As a result of experimental studies, it has been shown that the forced vibrations on the composite structure can be suppressed successfully with the application of the PID control design.

Süperiletken malzemeler kullanılarak oluşturulan sistemlerde deneysel yapının kurulmasından önce sitemin harektine bağlı levitasyon kuvveti gibi spesifik karakteristiklerini gözlemlemek ve tasarımı şekillendirmek için çeşitli analitik yaklaşımlar kullanılmaktadır. Maxwell denklemleri üzerinden elde edilen bu analitik yaklaşımlar ile kalıcı mıknatıs ve süperiletken malzeme arasındaki etkileşimi modelleme mümkün olmaktadır. Bu çalışmada manyetik alanın analitik olarak modellenmesini sağlayan H-formülasyonu yöntemi ile süperiletken manyetik yataklı doğrusal fırlatıcı sistemi için manyetik ray konfigürasyonu sunulmuştur. Bu çalışmada ele alınan sistemde insansız hava araçları için fırlatıcı olarak kullanılabilecek yapıya sahip doğrusal bir ivmelendirici sisteminin yataklanmasının süperiletken manyetik yataklar yardımı ile temassız bir şekilde gerçekleştirilmesi hedeflenmiştir. Dolayısı süperiletken ve manyetik ray arası etkileşimin incelenmesi ve levitasyon kuvvetlerinin hesaplanması gerekmektedir.

This study deals with Turkey-Iceland relations between 1930 and 1980. Relations between these two countries, which have completely different cultures and geographies, have always been limited because they have a long distance between them, and Iceland is a small market. The contacts which began indirectly in the 1930s evolved into an agreement that resulted in the abolition of visa requirements between these countries for three months in 1955. A few years after this agreement, diplomatic relations were established at the plenipotentiary level. Turkey's Embassy in Oslo and Iceland's Embassy in Copenhagen were accredited and started to fulfill this duty. Consulates were opened in both countries in 1960. These did not make any contributions to the trade or tourism of either country. Almost no commercial activities have been carried out between these countries so far. As for political activities, Iceland has generally pursued an anti-Turkey policy. Apart from its relations with third countries, Iceland is thought to be hostile especially towards Turkey. Therefore, Turkey should take more amicable steps to introduce itself to Iceland. This is the first study conducted on the Turkey-Iceland relations in the said period.

In this study, energy harvesting from cantilever composite beams produced at different lamination angles was experimentally investigated. In this regard, three different eight layered laminated composite beams are considered, i.e., {0°, 90°, 0°, 90°}s, {−30°, 60°, −30°, 60°}s and {−45°, 45°, −45°, 45°}s. energy harvest performances were analyzed under different external dynamics inputs by bonding piezoelectric material to the surface of composite beams. Firstly, the composite beam harvesting structure was excited by air-flow. In those experiments, three different types of bluff-body geometry elements were attached to the free end for each of the considered composite beams. In order to determine the maximum power output, different resistors are attached to the piezoelectric material. As a second dynamic input, an electromagnetic actuator operating on the Lorentz principle is used. By using this electromagnetic actuator, the structures are excited by harmonic inputs with different frequencies and frequency-voltage responses were obtained. Besides, vibration amplitudes and voltage outputs were analyzed for both excitation types.

Driving comfort and safety are important research areas in engineering and have been the subject of many studies. The objective of this work is the modeling and simulation of the disruptive effects coming from the road for the car suspension system. Disruptive effects from the road are modeled as bump geometry which represents the speed trap. There are different vehicle models are used in suspension control systems. The half-car model is selected in this study which has four degrees of freedom; the vertical movements of the front and rear axle, pitch and vertical motions of the vehicle body. The suspension system is the most important part of the vehicle that increases driving safety and passenger comfort by reducing road effects. The actively controlled suspension system is a type of vibration suspension structure popular in both the academic research and industrial application. As the control design, Linear Quadratic Regulator (LQR) controller is designed for half car active suspension system. In order to demonstrate the performance of the designed controller, a comparison has been made for the active and passive states for the suspension system. The designed controller was implemented to the active suspension control of the vehicle model modeled in Matlab-Simulink environment. Bump type speed trap profile is modeled as an input of the system. Simulation results show that the disruptive effects from the road is effectively damped when the active suspension is activated.