Wing rock phenomenon is undesired vibration in rolling angle occurring in delta wing aircraft at large angles of attack. This paper presents three versions of model refernce adaptive controllers; namely classical MRAC, s-modified MRAC and weighted s-modified MRAC to control the rolling dynamics under wing rock phenomenon with the presence of unmatched disturbance. The stability analysis of new proposed strategy for weighted s-modified MRAC has been presented. The effectiveness of the controllers is assessed in terms of their robusness under unmatched disturbance. The simulated results based on MATLAB/SIMULINK show that s-modified adaptive controller gives better robustness characteristics than classical one; as it could confine different aircraft responses within smaller bounded limits. Moreover, as compared to s-modified controller, weighted s-modified controller gives better enhancement in terms of robustness, control effort and error charcteristics.

According to myths narrations, Homa (osprey) was an auspicious fowl and prosperity messenger that sho was under the the protection of her, would have been wealthy and prosperous. This fowl is always mentioned by poets because it’s an osprey and didn’t hurt anything.Although Saeb has used these contents in his poetry, but has used literary arrays too, for example irony, allegory and simile the same as poets on his age. He has used norm breaking to present a different personality of osprey. Saeb believed that the reason of instability state of osprey and his disliking to her is because of her dark and transient shadow. The image of osprey presented by Saeb has made her as a terrestrial and tangible created.Also he believed that the reason of auspiciousness of this myth fowl is because of her humility and the reason of her fame is her satisfactory to some bones. So, Saeb didn’t want to be under the protection of osprey (homa) because he believed that prosperity is an inherent adjective not acquire.He used this myth fowl to describe nature and unimportant issues, that all of them are mentioned above and are analyzed in different accepts.

The Ornithopter configuration is inspired by birds and insects in the nature,Its electromechanical system performs the task of providing lift and propulsion forces by creating oscillation and reciprocating movement of the wing. This type of configuration has a higher stealth capability due to the lack of a high-speed engine, compared to fixed-wing and rotary-wing flying bodies. Improving the aerodynamic efficiency and mission performance of this type of configuration has been the focus of researchers,The current study experimentally investigates the effect of wing flexibility on the aerodynamic performance and the production of lift and thrust forces. Three types of rigid wing, and soft and hard flexible wings are designed and experimentally tested in the wind tunnel at different angles of attack and flapping frequencies. The results test showed that the effect of the dimensionless frequency on the lift coefficient increased with the increase of the angle of attack,at high angles of attack, especially in the rigid wing, the lift force coefficient has increased up to 90%. The range of optimal performance of each three mentioned bodies is presented.

Introduction: One of developments in field of radiology is providing the radiographic image based on computed radiography (CR) system. Common usable capabilities of CR system are obtaining super BW (Bite-Wing) images from digital panoramic views. Considering advantages of this system such as edge enhancement, we decided to evaluate the agreement of super BW with digital intraoral BW which is produced with PSP (Phosphor Storage Plate) system in detection of proximal caries.Materials & Methods: In this study, 40 patients with bilateral BW produced by intraoral PSP sensor (Digora Optime) and digital panoramic radiography which was taken with cassette containing storage plate (Konica Minolta) were selected. First, two super BWs were extracted from digital panoramic images of the patients and then proximal caries in digital intraoral BW and super BW images were evaluated by two different observers separately. In this study, the agreement between two methods was evaluated for each observer with kappa agreement test.Results: After analysis of data, it was revealed that there was a moderate agreement between two methods in detection of caries by first and second observers (0.454, 0.421). There was a poor agreement for detection of proximal caries of premolar teeth and a moderate agreement about molar teeth between first and second observers. Interobserver agreement for both techniques was good (0.664, 0.626).Conclusion: According to the findings of this study, it seems that due to a good agreement between two observers and a moderate agreement between two techniques about detection of caries, the use of super BW method instead of intraoral BW technique is not proper and therefore, using digital intraoral BW in detection of dental caries is preffered.

One of the reasons for the increase in induced drag is the vortices created at the wing tip, which has a significant effect on reducing aerodynamic efficiency. Therefore, in order to reduce vortices and the induced drag as well as to improve the aerodynamic performance, the use of wing grid is recommended. Wing grids perform better at low Reynolds numbers, and combination of parameters such as taper ratio, aspect ratio, and twist has a better effect on wing performance and reducing turbulence intensity and induced drag. The purpose of this paper is to improve the aerodynamic performance of compound wing using the wing grids. In this study, the numerical and experimental approaches have been used to investigate the effect of these parameters and also, two key parameters: the grid dihedral angle and sweep angle. Also, a force balance test has been performed for force analysis and numerical solution validation. Wing grid dihedral angle decreases induced drag by increasing the space between separated tip vortices and prevents reinforcing effects due to superposition. On the other hand, dihedral angle should be arranged to increase the aerodynamic efficiency. In other words, increase in dihedral angle may defect the overall performance of the wing. The optimum configuration is found to be symmetric, where the dihedral distribution with a 40° angle for the first grid is reduced gradually to a value of -20° for the last one. In addition, sweep angle distribution for the obtained optimized dihedral angle is also investigated. Initially, each grid span is decreased from the first grid to the last at a constant rate. This increases the sweep angle and enhances the aerodynamic efficiency by 15%. Furthermore, the span of the side grids is reduced from the middle grid and marching the wing leading and trailing edges. Elliptical wing configuration has also been shown to increase aerodynamic efficiency by approximately 50%.

The fixed-wing unmanned aerial vehicles (UAVs) have gained significant attention across diverse civilian and military applications in recent years, where precision control, advanced manoeuvrability, and elevated stealth capabilities are paramount. In order to design a robust control system to enable different tracking and path-following purposes, it is desired to establish a precise aerodynamic model. The research introduces a straightforward approach for accurately computing aerodynamic coefficients, essential for deriving aerodynamic forces and moments, particularly focusing on the rudderless flying-wing UAV models. Utilizing Digital DATCOM software, the study outlines a procedure for calculating the requisite aerodynamic coefficients of fixed-wing aircrafts. The data input card is prepared based on the design and physical attributes of the rudderless flying-wing Freya UAV model and its associated airfoil structure. Through the utilization of the input card in DATCOM software, computations are performed to determine static longitudinal/lateral stability, dynamic stability, and control coefficients, along with their derivatives. Additionally, a 3D model is constructed. The ensuing output file is then imported into the MATLAB environment for comprehensive analysis and integration into dynamic modelling for the design of control systems. The open-loop and closed-loop system performance analysis based on the obtained aerodynamic coefficients, shows acceptable values in terms of control surfaces and flight dynamics variables in the category of small-sized rudderless flying-wing UAVs which proves the reliability of the obtained results.

Extensive subsonic wind tunnel tests were conducted on a coplanar wing-canard configuration at various angles of attack. In these experiments, a 60o swept canard was placed upstream of a 60o swept main delta wing. This paper deals with the distribution of mean and fluctuating pressure coefficients on the upper surfaces of both the canard and the wing immersed in a variety of angles of attack. According to the results, presence of canard postpones the vortex formation and growth on the wing to higher angles of attack compared to the canard-off case. Due to the canard downwash field, the wing operates at lower effective angles of attack and therefore, its vortex breakdown is delayed. The spectral analysis of the unsteady pressure on both the canard and the wing show the existence of narrow, dominant frequency band containing the majority of the fluctuation energy. This frequency band is believed to be the natural frequency of the leading edge vortex. The results show that the dominant frequency of the wing vortex is lower than that of the canard having the same sweep angle as the wing, which is an indication of the wing vortex attenuation due to canard downwash field.

Delayed stall is the most dominant lift enhancing factor in insect flapping motion. Micro air vehicle operates at Reynolds number 104-105; slightly higher than the insects’ Reynolds number (Re). In the present research, thefocus is to investigate “ stall-absent” phenomenon at Re representative of the micro air vehicles, the effect of spanwiseflow on the leading edge vortex and also to study the effect of geometry variations on the aerodynamic performance of the wing in unsteady motion. Corrugated dragonfly airfoil with rectangular wing planform is used, however, with wing kinematics restricted to azimuth rotation only. Three-dimensionalfinitevolume method is used, through commercial software Fluent, to numerically solve time-dependent incompressible Navier-Stokes equations. Computed results at Re 34000 and 100, 000 reveal the same phenomenon of delayed stall, as observed in the case of insects. Furthermore, the performance of flat plate, profiled and corrugated wing in a sweeping motion at a high angle of attack is also compared.

Optimized structural architect of an Unmanned Lambda Wing Aerial Vehicle (ULWAV) during conceptual design has proven to be a significant challenge due to its unconventional configuration and no historical data for the structural architect. This paper aims to develop a new approach for structural design layout of new generation unconventional aircraft especially for ULWAV. The first step in this approach is to investigate the affecting parameters on structural architecture of these aircrafts then using of modal analysis to identification the behavior of these unconventional geometries for a general methodology development. The result of this modal analysis is apportion aircraft geometry to conventional substructures with already well-established defined architect. ULWAV structure architecture has been done by combining the structural architecture of sub-sections and with respect to requirements for systems installation, stealth design objective and packaging requirements. Here the CATIA software is used to optimize general architect with parametric model. To validate the results, the maximum static stress and maximum displacement of the structure were calculated using MSC / Patran software and compared with the values obtained from the optimization process. Dynamic analysis and buckling stability of structural composite shells are also controlled below. The architect methodology was applied to a case study of an ULWAV. The weight of the optimized structure has also been confirmed by typical case study researches.