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One of the challenges encountered in the design of guided projectiles is their prohibitive cost. To diminish it, an appropriate avenue many researchers have explored is the use of the non-actuator method for guiding the projectile to the target. In this method, biologically inspired by the flying concept of the single-winged seed, for instance, that of maple and ash trees, the projectile undergoes a helical motion to scan the region and meet the target in the descent phase. Indeed, the projectile is a decelerator device based on the autorotation flight while it attempts to resemble the seed’s motion using two wings of different spans. There exists a wealth of studies on the stability of the decelerators (e.g. the mono-wing, samara and pararotor), but all of them have assumed the body (exclusive of the wing) to be symmetric and paid no particular attention to the scanning quality of the region. In practice, however, the non-actuator-guided projectiles are asymmetric owing to the presence of detection sensors. This paper aims to present an analytical solution for stability analysis of asymmetric decelerators and apprise the effects of design parameters to improve the scanning quality.

The approach of this study is to develop a theoretical model consisting of Euler equations and apply a set of non-dimensionalized equations to reduce the number of involved parameters. The obtained governing equations are readily applicable to other decelerator devices, such as the mono-wing, samara and pararotor.

The results show that the stability of the body can be preserved under certain conditions. Moreover, pertinent conclusions are outlined on the sensitivity of flight behavior to the variation of design parameters.

The analytical solution and sensitivity analysis presented here can efficiently reduce the design cost of the asymmetric decelerator.

Designing new aircraft that are state-of-the-art and beyond always requires the development of new technologies. This paper aims to present lessons learned while designing, building and testing new UAVs in the configuration of the flying wing. The UAV contains a number of aerodynamic devices that are not obvious solutions and use the latest manufacturing technology achievements, such as 3D printing.

The design solutions were applied on an airworthy aircraft and checked during test flights. The process was first conducted on the smaller UAV, and based on the test outcomes, improvements were made and then applied on the larger version of the UAV, where they were verified.

A number of practical findings were identified. For example, the use of 3D printing technology for manufacturing integrated pressure ports, investigation of the adverse yaw effect on the flying wing configuration and the effectiveness of winglet rudders in producing yawing moment.

All designed devices were tested in practice on the flying aircraft. It allowed for improved aircraft performance and handling characteristics. Several of the technologies used improved the speed and quality of aerodynamic device design and manufacturing, which also influences the reliability of the aircraft.

The paper presents how 3D printing technology can be utilized for manufacturing of aerodynamic devices. Specially developed techniques for control surface design, which can affect adverse yaw problem and aircraft handling characteristics, were described.

This study aims to apply for the first time in literature a new multi-objective sensor selection and placement optimization methodology based on the multi-objective Lichtenberg algorithm and test the sensors' configuration found in a delamination identification case study.

This work aims to study the damage identification in an aircraft wing using the Lichtenberg and multi-objective Lichtenberg algorithms. The former is used to identify damages, while the last is associated with feature selection techniques to perform the first sensor placement optimization (SPO) methodology with variable sensor number. It is applied aiming for the largest amount of information about using the most used modal metrics in the literature and the smallest sensor number at the same time.

The proposed method was not only able to find a sensor configuration for each sensor number and modal metric but also found one that had full accuracy in identifying delamination location and severity considering triaxial modal displacements and minimal sensor number for all wing sections.

This study demonstrates for the first time in the literature how the most used modal metrics vary with the sensor number for an aircraft wing using a new multi-objective sensor selection and placement optimization methodology based on the multi-objective Lichtenberg algorithm.

This study aims to a launchable design has been made to prevent wasted time in time-critical areas, and increase the efficiency of the unmanned aerial vehicle (UAV). In this way, a UAV can reach the mission height quickly.

A unique launchable UAV and launcher mechanism have been designed. The launchable UAV will be folded into the launcher mechanism and will automatically start flight after launch. The study includes mathematical calculations, 3D designs steps and produced UAV tests for the designed UAV. The launcher mechanism was designed in accordance with the tests for the UAV, and appropriate choices were made for the altitude and launch acceleration required by the UAV. According to the calculations, material selection and production were made.

In the tests, the climbing time was reduced by 1 s compared with the existing UAVs. With the launch, it enabled it to reach the altitude quickly and silently. In addition, because the launch energy was provided externally, it provided an advantage for the flight time.

A rotary-wing UAV with a launch mechanism and a fast launch was designed and prototyped. The maximum climb speed of the designed drone is 6.52 m/s. Frame arm length is 9.2 cm, propeller diameter is 15.24 cm and hover flight time is 7.2 m.

The UAV design can be launched. Design, calculation and experimental studies have been carried out for rapid take-off of the rotary wing UAV. The parts used in the UAV are originally produced. It is not a commercial product.

A high-fidelity simulation platform helps to verify the feasibility of the controller and reduce the cost of subsequent experiments. Therefore, this paper aims to design a high-fidelity hardware-in-the-loop (HIL) simulation platform for the tail-sitter vehicles.

The component breakdown approach is used to develop a more reliable model. Thruster dynamics and ground contact force are also modeled. Accurate aerodynamic coefficients are obtained through wind tunnel tests. This simulation system adopts a mode transition method to achieve continuous simulation for all flight modes.

Simulation results are in good agreement with the flight log and successfully predict the state of the vehicle.

First, the effects of the propeller slipstream are considered. Second, most researchers ignore the parasitic drag caused by the landing gear and other appendages, which is discussed in this study. Third, a ground contact model is implemented to allow a realistic simulation of the takeoff and landing phases. Fourth, complete wind tunnel tests are conducted to obtain more accurate aerodynamic coefficients. Finally, a mode transition method is deployed in the HIL simulation system to achieve continuous simulation for all flight modes.

Successive Approximation Register-Analog to Digital Converter (SAR-ADC) has been achieved notable technological advancement since the past couple of decades. However, it’s not accurate in terms of size, energy, and time consumption. Many projects proposed to make it energy efficient and time-efficient. Such designs are unable to deliver two parallel outputs.

To this end, this study introduced an ultra-low-power circuitry for the two blocks (bootstrap and comparator) of 11-bit SAR-ADC. The bootstrap has three sub-parts: back-bone, left-wing and right-wing, named as bat-bootstrap. The comparator block has a circuitry of the two comparators and an amplifier, named as comp-lifier. In a bat-bootstrap, the authors plant two capacitors in the back-bone block to avoid the patristic capacitance. The switching system of the proposed design highly synchronized with the short pulses of the clocks for high accuracy. This study simulates the proposed circuits using a built-in Cadence 90 nm Complementary Metal Oxide Semiconductor library.

The results suggested that the response time of two bat-bootstrap wings and comp-lifier are 80 ns, 120 ns, and 90 ns, respectively. The supply voltage is 0.7 V, wherever the power consumption of bat-bootstrap, comp-lifier and SAR-ADC are 0.3561µW, 0.257µW and 35.76µW, respectively. Signal to Noise and Distortion Ratio is 65 dB with 5 MHz frequency and 25 KS/s sampling rate. The input referred noise of the amplifier and two comparators are 98µVrms, 224µVrms and 224µVrms, respectively.

Two basic circuit blocks for SAR-ADC are introduced, which fulfill the duality approach and delivered two outputs with highly synchronized clock pulses. The circuit sharing concept introduced for the high performance SAR-ADCs.

Dual-thrust hybrid unmanned aerial vehicle (UAV) technology offers a highly robust and efficient system that incorporates the take-off and landing capabilities of rotary-wing aircraft with the endurance capacities of fixed-wing aircraft. The purpose of this study is to model and control a hybrid UAV in three distinct flight modes: rotary-wing, fixed-wing and over-actuated model.

Model predictive control (MPC) along with linear models are applied to design controllers for the rotary-wing or vertical take-off and transition to the fixed-wing flight. The MPC algorithm is implemented with two approaches, first in its usual form and then in a new form with the help of tracking error variables as state variables.

Because the tracking error variables are more compatible with the cost function used in MPC, the results improve significantly. This is especially important for a safe and stable transition from rotary-wing to fixed-wing flight, which should be done quickly. The authors also propose a control allocation strategy with MPC algorithm to exploit the thrust and control inputs of both rotary-wing and fixed-wing systems for the transition phase. As the control system is over-actuated, the proposed algorithm distributes the control signal among the actuators better than the MPC alone. The numerical results show that the flight trajectory is also improved.

The research background is reviewed in the introduction section. The other sections are originally developed in this paper to the best of the authors’ knowledge.

This paper examines the political budget cycles in emerging and developing countries using a sample of 91 countries from 1992 to 2019.

This paper employs a pooled ordinary least squares (OLS) model with clustered standard errors at the country level. To address endogeneity issues, the authors also employ a two-step system generalized methods of moments model.

The authors find clear evidence of political budget cycles in emerging and developing countries. The authors consistently find that incumbents increase total government spending, particularly in economic affairs, public services and social welfare, in the year before an election and the election year. In contrast, they contract spending in the year after an election.

Policymakers should be aware of the political budget cycles during election years. Promoting control of corruption and democracy helps to alleviate the effects of the political budget cycles in emerging and developing countries.

The authors are among the first to explore the political budget cycles in emerging and developing countries by focusing on the total government spending and its main compositions, including expenditures on economic affairs, public services and social welfare. Besides, the authors also explore the conditioning effects of control of corruption, political ideology and democracy.