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The pea aphid, Acyrthosiphon pisum (Harris) is one of the most important pests of pea throughout the world.Host stage preference under choice and no-choice tests and age-specific functional response of Praon volucre (Haliday) parasitizing A. pisum were investigated. The experiments were carried out under laboratory conditions at 25 ± 1 °C, 60 ± 5% RH and a photoperiod of 14: 10 h (L: D). Functional response of P. volucre was evaluated in adult lifetime at seven host densities (2, 4, 8, 16, 32, 64 and 128). Praon volucre strongly preferred to oviposit into first and second instar nymphs in both choice and no-choice conditions. Parameter estimation of logistic regression revealed type III functional response for P. volucre in first and second days and type II from third to the end of parasitoid lifetime. The handling time (T_h) and searching efficiency (a or b) were estimated using the Rogers equation. The shortest and longest handling times were at fourth day (T_h = 0.19 ± 0.04) and 8^th day (T_h = 0.94 ± 0.15), respectively. The highest searching efficiency (a) was 0.048 ± 0.007 h^-1 on third day and lowest searching efficiency was observed at the end of parasitoid lifetime (6^th day-8^th days). The maximum attack rate ranged from 126.31 nymphs/24 h on fourth day to 25.53 nymphs/24 h on 8^th day. The results of this study revealed that the age of adult parasitoid can change the functional response from type III to type II, indicating that this factor may contribute to stabilization of parasitoid–prey dynamics.

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The study of insect morphology has recently benefited greatly from the emergence of new digital imaging and analysis technologies such as X-ray Micro-computed tomography (μ-CT), digital 3D reconstruction, and animation. Through interactive gaming and virtual reality, the external morphology of insects can be studied by a broad audience of both entomologists and non-specialists. EntomonVR is a serious game designed to investigate the external morphology of insects with adequate quality for the virtual reality platform. In this research, we discuss the advantages of virtual reality, introduce the EntomonVR new educational game, and conclude about future perspectives, validations, and cost-effectiveness. We tested this game on 25 participants with an entomological background for assessment and improved it based on their feedback. This study demonstrates the efficacy of virtual reality technology for an experimental learning environment in teaching the morphology of insects and the crucial need for advancing an efficient and interactive educational program.

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The purpose of this paper is to investigate the effect of unsteady trailing edge flapping on lift generation for fixed airfoils at low angles of attack. To do this, a 2D unsteady compressible flow around a fixed airfoil is analyzed at different angles of incidence by means of Coarse Grid CFD (CGCFD) method with spring dynamic network. In this method Euler system of equation is solved with coarse Grid and no slip boundary condition using vorticity confinement technique. At first for code validation, the results of fixed airfoil at different angles of attack and also pitching airfoil are compared with experiments. Further, the CGCFD consequences are compared with the results of RANS with SA turbulent model in the quasi steady case. Then trailing edge flapping (TEF) is added to the fixed airfoil at low angles of attack. The effects of unsteady parameters such as the amplitude and the frequency of TEF are investigated at different low angles of attack. The results show that in a specific low angle of attack, adding TEF results in increasing the lift coefficient comparing with the fixed airfoil without TEF.

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The flight dynamics of nine configurations of supersonic continuous deflectable nose guided missiles have been investigated. The studied configurations consist of a spherical nose tip, a tangent ogive, a set of stabilizing tail fins and a cylindrical body that its mid-section is flexible to form an arc of a circle. So the cylindrical body consists of a fix part in vicinity of nose, middle flexible part and main body with stabilizers. The effects of fix length and flexible length parameters on the flight dynamics of surface to surface, antiaircraft and antimissile missiles have been studied. A code has been developed to solve full Navier-Stokes equations using finite volume and modified Baldwin-Lomax turbulence model. Further, a 3 degree of freedom code has been developed to compare planar flight dynamics of missiles. This code consists of a guidance subroutine based on pure persuit law. The results show that even increase of fixed and flexible lengths enhance the maneuverability of the missile, but in some scenarios this can lead to increased flight time and more errors in the target engagement. Deflected nose relocates mass center away from the axis and a thrust vector torque is created. Study of surface to surface scenario shows that this torque improves accuracy of targeting and the ability of target dislocation. In air defense missiles, increase of Fix and Flex variables, will extend the limits of allowable firing angle. However, a heavy nose increases the role of thrust torque and subsequently decreases the role of nose geometry.

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Stability and transparency are both very important conditions in bilateral teleoperation systems. For the design of such systems, different methods have been suggested. Among the approaches presented, passivity framework is widely utilized in which human and environment is considered passive. The operator does not make the closed-loop system unstable. In addition, it is passive against an external input. Thus the adoption of this assumption is correct for the human. Nevertheless it is a conservative presumption for the environment and according to some modern applications of teleoperation systems such as cardiac surgery, it is absolutely not acceptable. In this paper a novel control structure for nonlinear bilateral teleoperation systems interacting with active environments is addressed. In this approach, first a criterion for measuring activity of the environment is presented. Then by developing a PD controller, an algorithm that guarantees master-slave position coordination and static force reflection is introduced. The overall stability of closed loop system is proved using passivity concept and Lyapunov-Krasovskii technique. Simulations are performed to verify the performance of the proposed bilateral teleoperation systems in contact with passive and non-passive environments. Experimental results were carried out to validate the theoretical consequences.

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In this paper simulation of steady super cavitation phenomenon اhas been considered by using partial non-linear model of Boundary Element Method(BEM).The grid mesh used is fixed and the strength of dipole and source are constant on each element. With the assumption of a partial non-linear model the cavity condition is applied on the body with the assumption that cavity height is low. Thus there is not any calculation on the cavity surface, but it is restricted to only the panels on the body surface. Cavitation number is known at first and the cavity length is determined in every iteration. When the lengths obtained in two successive iterations are very close to each other it assumed to be the answer. Based on this method two Kutta conditions including Morino condition and Iterative Pressure Kutta Condition(IPKC) are studied to satisfy the wake surface condition. The application is a wing with NACA16006 section. Iterative pressure Kutta condition compared to Morino condition needs higher computational costs, but on the other hand leads to more accurate results. It has been shown that the simulation of the flow with super cavitation over wing leads to a pressure difference at the trailing edge of each strip if we use Morino’s Kutta condition. While if Iterative Pressure Kutta Condition is usedthe results are satisfactory. Comparing the results show that this method leads to very accurate predictions for the behavior of flows with cavitation, while significantly lower computational cost is required if we use the simple cavity closure condition.

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In this article, cavitation flow around axisymmetric projectiles with ringed and non-ringed cavitator has been investigated using control volume and boundary element methods. In the numerical method, the homogeneous equilibrium approach as well as the zwart model, for modeling the mass transfer and forming the system of equation, have been used. In the boundary element approach with dipole distribution on the body and cavity surfaces and source distribution on the cavity surface, the right conditions were set for using the Green's theorem in solving the potential flow. Moreover, some source components were imposed on the cavitator surface in order to add the hole effects. The validation procedure for both methods has been done by analytical and experimental data. In general, the results of this research are presented in two parts. In the first part, hydrodynamic properties of ringed cavitator such as cavity dimensions, intended forces, flow behavior and etc are analysed deploying the numerical methods based on Navier Stokes equations. In the second part, the boundary element method has been used for the analysis of the cavitation flow around practical geometries with ringed cavitator. The most important finding of this study is reduction of the cavity dimensions and also an increase in the force on the projectile during the use of annular cavitator. In addition, as a result of this study, two equations for maximum length and maximum diameter of the formed cavity on the cylindrical body in relation to the cavitation number and hole diameter have been provided.

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This study, deals with the investigation of the accuracy and performance of a novel method for simulation of oscillating wave surge converter (OWSC). The OWSC is an instrument with one degree freedom mounted in near shore areas which oscillates back and forth. This device is used to harvest sea wave energy. The developed model is based on the well-known volume of fluid (VOF) method. Due to the nature of the OWSC motion, the VOF method in conjunction with unstructured dynamical grid mesh has been used in the literature. But in this study, a structured grid mesh is employed which facilitates the numerical preparation and the speed of simulation process. The results are compared with the experimental data and the results of numerical method in the literature by dynamical grid mesh. This comparison shows the high accuracy of the developed model in this study. The model validation is performed in an extreme condition with steep waves which need an accurate numerical scheme. The external forces including power take off (PTO) forces are also simulated. The capture factor, energy absorption condition and the effect of PTO on angle, angular velocity and slamming of the OWSC are also investigated. Finally, the effect of wave height and the PTO stiffness on the capture factor and absorbed energy by the OWSC for waves with a specific period are investigated.