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In order to study the flexible deformation process of the micro flapping wing during its fluttering, the dynamic three-dimensional reconstruction of the wings is carried out by the RealSense SR300 depth camera. The wing flapping parameters is measured and the deformation of different wings flapping are analyzed. The results show that the wing deformation of the large flexible wing is irregularly adaptive during the flapping process, and it has a larger amount of arch deformation, and the asymmetry of the flexible deformation of the wings on both sides is greater than that of the small flexible wing.

In this paper, a prototype of a hovering flapping wing micro air vehicle is developed. The aerodynamic force of the prototype at different flapping frequencies and pitch angles is measured, and a hovering flight control scheme for the vehicle is designed based on the measured results. Finally, a flight test of the prototype is carried out. The tail deflection of the prototype is controlled by a micro linear rudder, and the pitch attitude of the prototype is adjusted during flight. The hovering flight within a certain range is realized. The feasibility of the hovering flight control scheme of flapping wing micro air vehicle is verified.

Various stroke trajectories may be observed in insect hovering flight in nature; however their influences on the flight performance of insect are not well estimated. In this study, a numerical investigation into the effects of stroke trajectories on the aerodynamic performance of insect hovering flight is carried out through the solution of the two-dimensional unsteady incompressible Navier-Stokes equations. An insect wing model with ellipse cross section in hovering flight is considered for the purpose and four types of idealized trajectories (Named linear, oval, figure-eight and double-eight) which possess different deviation characteristics from the stroke plane are examined. The influences of the deviation amplitude of trajectory, the attack angle of wing and the inclined angle of stroke plane on the aerodynamic characteristics of hovering wing are systematically analyzed. The results show that in the case of the wing in a normal hovering flight where the stroke plane is horizontal, the trajectory deviation from the stroke plane weakens the aerodynamic performance for each trajectory case considered, and this deteriorative effect becomes more serious as the amplitude of deviation increases. With regard to the influence of the angle of attack, the results show that the time-averaged drag force and power consumption increase monotonically with the angle, whereas the time-averaged lift force and the lifting efficiency increase first and then decrease as the angle increases further. In the case of a hovering flight with an inclined stroke plane, distinctly different trends from a normal hovering flight are obtained.

A numerical study on the effects of the asymmetry in flapping motions on the aerodynamic performance of a 2-D inclined hovering wing is carried out through the solution of the two-dimensional unsteady Navier-Stokes equations. Asymmetric flapping motions with different flapping durations as well as different angles of attack during downstroke and upstroke are considered, correspondingly the aerodynamic forces, the energy consumption and the flow structures of the wing are examined for the purpose. The results show that the asymmetry either in flapping duration or in angle of attack can effectively alter the aerodynamic characteristics of the wing. It is found that much larger vertical force is generated in the downstroke with smaller duration. As for the angle of attack, an increase in the angle during the downstroke gives rise to a larger vertical force and lifting efficiency while for the upstroke the increase in the angle results in a larger thrust force. Furthermore, a combined model with asymmetry in both flapping duration and angles of attack is also studied and the results show that a combined flapping motion with a faster downstroke and a higher downstroke angle of attack can produce much larger vertical force than a motion with asymmetry simply in stroke duration or angle of attack. The present results provide physical insight into a better understanding of the asymmetric stroke mechanisms in the flapping motion of insects.

High performance infrared light emitting diodes (LED) have drawn wide attention because of their significant applications in biomedicine, agriculture, aquaculture, night vision security systems and scientific researches. Due to the rapid development of infrared up-conversion devices, especially in the terahertz (THz) region, the studies on the GaAs-based infrared LEDs operating at low temperature ( 150 K) than that of the DH-LED. A developed rate equation method is used to analyze the ELE superiority of the QW-LED. Finally, the surface EL uniformity of the two LEDs was studied by using the charge coupled devices (CCD) imaging. This study provides a guidance to choose and design LED structures for different operation temperatures.

Mobile vocabulary learning is the trend of vocabulary learning nowadays. This paper takes “Youdao Memorizing Words App” in China as an example to make an empirical study on the effectiveness of mobile vocabulary learning software. The results show that students’ vocabulary competence improves by using this App. So it is effective to learn English vocabulary by mobile software. Students think that the software helps them most by building their learning habits.

Inspired by the fact that flexible wing in nature possesses advance aerodynamic performance, a numerical experiment is applied to investigate the aerodynamic performance of flexible wing in plunge motion, where the incompressible Navier-Stokes (N-S) equations coupled with the structural dynamic equation for the motion of the wing is solved. A two-dimensional, elastic and inextensible beam model wing is considered at Re = 1256. The harmonic plunge motion is specified at the leading edge of wing, and the other part of wing is responded passively deforming by the aerodynamic force. By analyzing the flow field, aerodynamic force and energy efficiency of different flexibility wings, it is found that the flexibility influences the aerodynamic characteristics of the plunge wing greatly and when the plunge frequency is less than the structural frequency the flexibility can increase the thrust force and the energy efficiency of the wing, and the maximum energy efficiency is obtained when the wing plunge near the resonance. Moreover, a lighter wing possesses larger energy efficiency than a heavier wing, but it may not be functioning for too light wing. The results obtained in this study will provide physical insight into the understanding of fluid and structure interaction problem.

Rain-wind-induced vibration (RWIV) appeared on cable stayed bridges involves complicated fluid and structure interactions and its mechanism is not fully understood. It is believed that the upper-rivulet which is often seen when the RWIV occurs plays an important role. In this paper, a numerical investigation on the effects of the upper rivulet on the aerodynamic forces of the cable and the interaction between the fluid flow and the cable oscillation is carried out where the cable with the upper-rivulet is modeled by a circular cylinder with an arch attachment. The Reynolds number of 6.8×104 is selected. The large-eddy simulation (LES) method with Smagorinsky-Lilly modeling is employed to simulate the 3-D turbulent flow field, and a moving mesh method is introduced to deal with the oscillation of the cylinder. The aerodynamic forces on the cylinder and the flow patterns around the cylinder are analyzed for both steady and oscillation status of the cylinder with the rivulet attachment in different position angle ranged from 0° to 60°. The results show that the aerodynamic forces on the cylinder change largely with the position angle of the rivulet attachment. In the steady cases, a uniform recirculation flow along the axial direction of the cylinder forms behind the cylinder; whereas in the oscillation cases, a 3-D periodical recirculation flow appears along the axial direction. The scales of these recirculation zones are influenced by both the position angle of the rivulet and the dynamic status of the cylinder. The results also show that there exists a rivulet position angle where the aerodynamic force on the cable and flow pattern around the cable both change dramatically. This critical position angle is found to be 45° for the cases studied.

In this paper, a new type of flapping wing robot inspired by silver gull is designed, of which the flapping wings can fold and twist in highly bionic way. Firstly, the CAD model is built using SolidWorks. Secondly, the mathematical mechanism model is established to analyze the kinematic characteristics, meanwhile the kinematic simulations carried out with ADAMS. Finally, the physical flapping wing robot is manufactured. The design results can be used to provide reference for the bionic design of large birds.

The effects of tripping rods on characteristics and fluid forces acting on a single cylinder was three-dimensional numerical studied in a low laminal flow at a Reynolds number of 200 and a subcritical stream at a Reynolds number of 5.5X104. The angular position of the tripping rods was varied from 20 to 60.The results reveal that there exits an optimum position of tripping rod for reducing fluid forces. This optimum angular position was found to be 40° for Re=200 and 30° for Re=5.5X104. At this optimum angle, the steady drag, fluctuating drag and fluctuating lift forces acting on the cylinder are reduced by 21%, 32%, and 28% for Re=200 and 36%, 44%, 76% for Re=5.5X104.

The flexion effect of a flexible wing during the hovering flight is systematically studied by using computer simulations when Reynolds number is kept at 140. The aerodynamic forces and flow vortex are investigated by solving the two-dimensional time-dependent incompressible Navier–Stokes equations using the finite volume method. The wing is modelled as a thin plate which has a rigid leading portion and a flexible aft part. The simulations are performed for a variation of the location of rotational centre and the amplitude of the flexion, and the corresponding changes of the aerodynamic forces and vortex shedding mechanism in the wake structure are investigated. Form the quantitative comparisons, the present simulations reveal that a moderate flexion during the hovering fly can provide a better performance for a flapping wing, while an excessive flexion will lead the aerodynamic performance become worse. Though the flexion does not change the force trace of the hovering wing, the magnitude of the instantaneous peak forces and mean periodic forces are definitely changed by the chordwise deformation. Compared with a rigid hovering wing, the dynamic flexion during hovering alters the intensity of the leading edge vorticity and the transfer direction of the wake. Here, the present results indicate that the aerodynamic forces can be altered by adding some deformation characteristics to the trailing edge of the wing. Furthermore, the appropriate flexion can be used to alter the aerodynamic performance of a wing and will be helpful for design and control of the flexible microflying vehicles.

Rain-wind induced vibration (RWIV) is a violent oscillation that appears on cable stayed bridge under rainy weather. Many researchers agree that the rivulets (specially the upper one) play an important role during the vibration. In present work, the upper rivulet’s effect is focused. A circular cylinder with an arches attachment on its surface is modeled to take the place of cable- rivulets system section in RWIV. Using finite volume method (FVM), 3D Flow past the cylinder-arch model is simulated for subcritical Reynolds Number (Re, ≈6.8×104). Large Eddy Simulation (LES) method is drawn in as a closure of turbulence model. The attachment locating at different positions are calculated. The results show many differences between cylinder-arch model and bare circular cylinder, including force coefficients change dramatically and velocity distributions in wake zone vary remarkably. Responses of cylinder-arch system driven by aerodynamic forces are also studied. Fourth order Runge-Kutta Method is introduced to solve second order ODEs that describe the vibration of cylinder model. The first four modal response are calculated and then added to analyze cable oscillating properties.

A numerical investigation on the effects of small tripping rods on the fluid force reduction on a big structure has been carried out using finite volume method where a configuration of a circular cylinder with two small tripping rods symmetrically placed very near to its front surface is studied. The diameter ratio of the rods and the cylinder is set at 0.08, 0.10 and 0.12, and the gap between the rods and the cylinder is fixed at 0.08 of the cylinder diameter. The angular position of the rods varies from 20° to 60°. The effects of the tripping rods on force reduction, vortex shedding frequency and flow separation have been examined for various arrangements of the rods with Reynolds number focused on 200 for laminar flow and 5.5×104 for a turbulent flow. The results reveal that there exits an optimum position where the time averaged force coefficients acting on the cylinder all reach their minimum values and at the same time Strouhal number meets its maximum. At the optimum position the drag coefficient is reduced by 18% for Re=200 and 59% for Re=5.5×104. Further investigation with tripping rods placed near the separation points is also carried out for Re=5.5×104 and a considerable drag reduction is found.

© 2015 IEEE. This paper introduces the design and development process of a flapping wing air vehicle (FWAV) and the modified Silver-Gull inspired flapping wing air vehicle (SGFWAV). The selection of the flapping mechanism, power source, material and the associated manufacturing methods are discussed. Free flight test showed that the flapping of the wings were unstable due to the configuration of the flapping mechanism. A modified flapping mechanism is applied on the SGFWAV. The mathematical model of the SGFWAV is established and initial flight simulation indicates that the tail's motion generate additional aerodynamic lift and propulsive forces for the SGFWAV.

Background Osteonecrosis of the femoral head (ONFH) is generally characterized as an irreversible disease and tends to cause permanent disability. Therefore, understanding the pathogenesis and molecular mechanisms of ONFH and developing effective therapeutic methods is critical for slowing the progress of the disease. Methodology/Principal Findings In this study, an experimental rabbit model of early stage traumatic ONFH was established, validated, and used for an evaluation of therapy. Computed tomography (CT) and magnetic resonance (MR) imaging confirmed that this model represents clinical Association Research Circulation Osseous (ARCO) phase I or II ONFH, which was also confirmed by the presence of significant tissue damage in osseous tissue and vasculature. Pathological examination detected obvious self-repair of bone tissue up to 2 weeks after trauma, as indicated by revascularization (marked by CD105) and expression of collagen type I (Col I), osteocalcin, and proliferating cell nuclear antigen. Transplantation of hepatocyte growth factor (HGF)-transgenic mesenchymal stem cells (MSCs) 1 week after trauma promoted recovery from ONFH, as evidenced by a reversed pattern of Col I expression compared with animals receiving no therapeutic treatment, as well as increased expression of vascular endothelial growth factor. Conclusions/Significance These results indicate that the transplantation of HGF-transgenic MSCs is a promising method for the treatment for ONFH and suggest that appropriate interference therapy during the tissue self-repair stage contributes to the positive outcomes. This study also provides a model for the further study of the ONFH etiology and therapeutic interventions.

This research focuses on the flapping wing mechanism design for the micro air vehicle model. The paper starts with analysis the topological structure characteristics of Single-Crank Double-Rocker mechanism. Following the design procedure, all of the possible combinations of flapping mechanism which contains not more than 6 components were generated. The design procedure is based on Hong-Sen Yan's creative design theory for mechanical devices. This research designed 31 different types of mechanisms, which provide more directions for the design and fabrication of the micro air vehicle model.

This research aims at developing a flapping wing micro air vehicle model. The development of micro air vehicle model is a complex project involved with micro power transmission system design, low Reynolds number aerodynamics analysis, wind tunnel experiment, flight control algorithms and energy supply etc. This research focus on the field of flapping mechanism design and optimization, the aerodynamic layout of wing and tail design was also involved. The finally designed model was fabricated using traditional machining process with a total 14.88 g including the electronic module. Initial experiments showed that the spatial flapping mechanism based FMAV model provided a symmetric and steady flapping motion.

A systematic aerodynamic analysis for the wing of a micro flying robot hovering with different kinematics at a Reynolds number of 140 is carried out through the numerical solution of the two-dimensional time-dependent incompressible Navier-Stokes equations. Special attention is paid to the effect of the stroke trajectories on the aerodynamic forces and vortex shedding mechanism of the hovering wing. Six types of trajectory are selected which are line, oval, inverse-oval, eight, inverse-eight and double-eight, and for each case a harmonic hovering pattern is examined. In addition, the fruitfly hovering trajectory is also analyzed. A quantitative comparison of the aerodynamic forces and vortex structure between different trajectories is present. The simulation results reveal that the varied trajectory pattern results in significant differences in vortex structure around the wing, which indicates that an appropriate stroke deviation can be used to steer the maneuverable performance of the micro flying robot.

A systematic study for the flow around a deformable wing heaving in a prescribed motion at a Reynolds number of 104 is carried out through the numerical solution of the two-dimensional unsteady incompressible Navier-Stokes equations. Special attention is paid to the effect of the frequencies and amplitudes of the flexure wing on the wake structure and vortex shedding mechanism. The effect of flexible features on the forward flight of the wing is discussed by comparing the flow structures with those around a rigid wing. The simulation results reveal that the thrust efficiency of the deformable wing is higher than the rigid wing. The efficiency is improved because of flexure and is predominantly influenced by the reduced frequency.

It is becoming evident that sustainable development methods are now being considered by governments and corporations from all countries at both local and global level. Firms are increasingly looking to strike a balance between profit, preserving the local environment, and energy savings, rather than just looking for profit. In this paper, an enterprise input–output analysis based on production processes is used to investigate two tile manufacturers, one located in China and the other in Italy. The aim of the paper is to describe their energy/materials use and consequent pollution/waste emissions, and to make a comparison between them. As this industry uses huge quantities of energy, it is useful to monitor these consumption uses along with pollution levels. This accounting can help in planning future local development strategies that would make production cycles more efficient and sustainable.

A numerical investigation of the influence of pitch angle on vertical axis wind turbine (VAWT) aerodynamic performance is carried out using the finite volume method. The attack angle of the wind turbine is studied under a speed ratio λ = 3D 4, and the pitch angle of the wind turbine is adjusted to optimize the working attack angle and hence the aerodynamic performance of the turbine. The flow is assumed to be 2D fully turbulent and the fluid is incompressible, and turbulence is modeled by the k-w SST. The sliding mesh technique is adopted. The present study shows that an appropriate pitch angle can apparently improve the wind turbine power-coefficient.

Background Autologous transplantation of modified mesenchymal stem cells (MSCs) is a promising candidate for the treatment of the refractory clinical disease, avascular necrosis of the femoral head (ANFH). Our previous attempts by compounding MSCs with medical fibrin glue to treat ANFH in animal model have achieved excellent effects. However, the underlying molecular mechanism is unclear, especially on the transgenic gene expression. Methods Rabbit MSCs were isolated and compounded with fibrin glue. Following degrading of fibrin glue, proliferation, viability, expression of transgenic hepatocyte growth factor gene as well as osteogenic differentiation of MSCs were evaluated together with that of uncompounded MSCs. Fibrin glue-compounded MSCs were transplanted into the lesion of ANFH model, and the therapeutic efficacy was compared with uncompounded MSCs. One-Way ANOVA was used to determine the statistical significance among treatment groups. Results Fibrin glue compounding will not affect molecular activities of MSCs, including hepatocyte growth factor (HGF) secretion, cell proliferation and viability, and osteogenic differentiation in vitro. When applying fibrin glue-compounded MSCs for the therapy of ANFH in vivo, fibrin glue functioned as a drug delivery system and provided a sustaining microenvironment for MSCs which helped the relatively long-term secretion of HGF in the femoral head lesion and resulted in improved therapeutic efficacy when compared with uncompounded MSCs as indicated by hematoxylin-eosin staining and immunohistochemistry of osteocalcin, CD105 and HGF. Conclusion Transplantation of fibrin glue-compounding MSCs is a promising novel method for ANFH therapy.