In this paper, by defining a new paradigm for nonlinear aerodynamic equations of flow separation and Static stall, a new form of nonlinear aeroelastic equations for two degrees of freedom airfoils (torsional and bending) are presented. Structural equations are based on the nonlinear mass-spring model which includes the nonlinear quadratic and cubic terms. Aerodynamic equations are obtained by combining the unsteady Wagner model and the nonlinear lift coefficient-angle of attack for simulating stall using a cubic approximation. Hamilton’s principle and Lagrange equations were used to derive the aeroelastic equations. The obtained integro-differential nonlinear aeroelastic equations are solved using a timehistory integration method. The aeroelastic behavior of the airfoil is compared in both unsteady and quasi-steady flow. Using the time-history method compared to the phase space method leads to fewer equations. The results show that the aeroelastic behavior of airfoil with a linear structure, using a nonlinear aerodynamic theory for the stall, causes oscillations with a limit cycle in unsteady and quasisteady flow compared to other linear aerodynamic theories. Also, the use of the cubic curve instead of the piecewise linear curves which are commonly used in other references, causes an apparent complication of the equations, reduces the computational time due to faster convergence in solution and makes the reduction in errors. The results show that the use of nonlinear aerodynamic Static stall not only reduces the instability velocity, but also reduces the amplitude of limit cycle oscillations in both unsteady and quasi-steady regimes.

In this paper, the dynamic instability of swept wings by using the geometrically exact fully intrinsic beam equations and with considering the Static stall effects is investigated. Study of variations of the limit cycle amplitudes by using the fully intrinsic beam equations and ONERA unsteady aerodynamic model with Static stall effects in swept wings is the achievement of this article. the geometrically exact fully intrinsic beam equations involve only moments, forces, velocity and angular velocity, and in these equations, the displacements and rotations will not appear explicitly. In this study, the aerodynamic loads on the wing in an incompressible flow regime are determined by using the ONERA unsteady aerodynamic model. In order to check the instability behavior of the system, first the resulting non-linear partial differential equations are discretized by using the central finite difference method, and then time responses are obtained. The obtained results are compared with those available in the literature. Furthermore, the effects of sweep angle are studied. Finally, it is observed that by using the geometrically exact fully intrinsic beam equations, the instability of the swept wings can be determined accurately and selection of suitable sweep angle can postpone the occurrence of limit cycle oscillation.

Background and Aim: The aim of the present study was to investigate the effect of the Hand Static Rest Splint on reducing the pain and other compliance of Rheumatoid Arthritis (RA). Materials and Methods: In the present clinical trial, 12 patients, aged 35-50 (average: 39 years) with RA, referring to the Occupational Therapy Unit of Taleghani hospital and meeting America College of Rheumatology diagnostic criteria, were included. Visual Analogue Scale (VAS) was administered and swelling, tenderness and morning stiffness were assessed. Moreover, assessments of active range of motion using goniometry and grip strength with Jamar dynamometer in both hands were performed. Statistical analysis of data was performed using t-test and Mann-Whitney Test for two independent samples and willcoxon tests and paired t-test for paired samples run in SPSS, version 18. The level of significance was set at p˂ 0. 05. Results: The findings showed that the Static Rest Splint led to improvement in the wrist range of motion (flexion p=0/005, extension p=0/03) when the two groups were compared, but it did not have a significant effect on Morning Stiffness (p=1), pain (p=0/1), Swelling (p=0/06), and Tenderness (p=0/2). However, when compared between after and before intervention in hand with splint, pain (p=0/02) and wrist range of motion (p=0/004) improved. Conclusion: Based on the findings of the current study, and since using splints only improve range of motion in the wrist compared between two groups and pain relief before and after the intervention, it seems that using hand Static Rest Splint to reduce other symptoms need further investigation and also given that the use of this position without stress on the tendon can be effective in reducing the causes deformity, further studies are needed to more delineate these points.

The present research investigates the torsional aeroelasticity of the blade of an H-type vertical axis wind turbine subject to stall and post-stall conditions in various Reynolds regimes, which is experienced by the blade in a full revolution. In order to simulate the aerodynamics, a new model based on a combination of the Double Multi Streamtubes (DMST) model and the nonlinear multi-criteria Cl- equations, which is depended on the local Reynolds number of the flow, has been proposed. The results indicate that using of multi-criteria function dependent on the Reynolds number for the Cl- curve has improved the prediction of the torsional behavior of the blade in azimuthal rotation of the blade compared to using single-criterion functions and linear aerodynamics. The blade’ s aeroelastic torsion has been studied for various TSR values.

The unstable flow with rotating-stall-like (RS) effects in a rotor-cascade of an axial compressor was numerically investigated. The RS was captured with the reduction in mass flow rate and increasing of exit Static pressure with respect to design operating condition of the single rotor. The oscillatory velocity traces during the stall propagation showed that the RS vortices repeat periodically, and the mass flow rate was highly affected by the blockage areas made by stall vortices. The results also showed that large scale vortices highly affects on the generation and growth of the new vortices. An unsteady two-dimensional finite-volume solver was employed for the numerical study which was developed based on Van Leer’s flux splitting algorithm in conjunction with TVD limiters and the κ-ε turbulence model was also employed. The good agreement of the computed mass flow rate with the experimental results validates the numerical study.

In this paper, a new model is developed for rotating stall in low speed axial compressors and fans. The theory is developed from Moore’s theory. The modified model makes it possible to predict the transient behavior of the stall cells, which is not possible with Moore’s theory. The general assumptions such as the layout of the compression system, the lags in the entrance and exit ducts, and the small disturbances are assumed to be similar to those of Moore’s theory. However, a second order hysteresis is used in the current work for the pressure rise of the rotor and stator rows. Comparing the experimental results with the theory shows that the modified model can predict the transient behavior of the stall cells fairly accurately. Furthermore, the current model makes it possible to study the effects of different parameters such as the stagger angle, number of stages, and number of stall cells. It has been suggested in the current study that the number of stall cells should reduce to one in a fully developed rotating stall pattern.

The first step in turbine blade design is to select tip speed ratio. In this research, the optimum speed ratio is calculated with regard to the dynamic stall phenomenon. The dynamic stall imposes large amplitude loading on airfoil sections and since it occurs in turbine operating envelope in unsteady flow. The purpose of this study was to investigate the effect of unsteady flow with periodic oscillation on the performance of horizontal axis wind turbines. A dynamic stall model is implanted to analyze the Static data obtained. Then, using this model and blade element momentum theory, the optimal tip speed ratio is calculated. Also, thrust and power coefficients are plotted in several different tip speed ratios. In addition to dynamic results, Static results are plotted in power and thrust graphs. Comparison of these results shows how the dynamic stall causes the deviations of responses to Static state. This phenomenon affects the efficiency by -3% as compared to the Static stall. Also the optimum tip speed ratio increases in dynamic mode. In addition, time average diagrams of the drag coefficient show that the delay in separation starts approximately from the midpoints of the blade and reaches the maximum value at the root.

Fungi release wide spectrum of volatile organic compounds (VOCs) that belong to several chemical groups with different biochemical origins such as monoterpenes, sesquiterpenes, alcohols, aldehydes, aromatic compounds, esters, furans, ketones, sulfur and nitrogen compounds. Trichoderma species are the most studied fungal biocontrol agents and are successfully used as biofungicides and biofertilizers in greenhouse and field. Volatile metabolites play a key role in mycoparasitism of Trichoderma spp., as well as in their interactions with plants and other organisms in their environments. Based on the antibiotic activity of these fungi against the fungal pathogens, further consideration of their VOCs profiles, has been offered. In this study, VOCs of native Trichoderma species from Iran (T. harzianum, T. virens (6011), T. atroviridae (1-3)) have been identified by Static headspace gas chromatography-mass spectrometry The most of detected compounds were related to monoterpenes and sesquiterpenes. These are including; dl-limonene; beta-himachalene; beta-cubebene; cadinene; caryophyllene; alpha-gurjunene; farnesol; thujopsene; beta-bisabolene and alpha-farnesene. Based on antifungal effects of these compounds, biological control of these Trichoderma species can be related to them. These VOCs could be potential sources for purposes of chemotaxonomy and natural fungicides to protect crops from the fungal pathogens without environmental problems.