The development of strain sensors featuring both ultra high sensitivity and stretchability is still a challenge. We demonstrate that based on fragmented single-walled carbon nanotube (SWCNT) paper embedded in poly(dimethylsiloxane) (PDMS) can sustain their even at very levels (with gauge factor over 107 50% strain). This record ascribed to the low initial electrical resistance (5-28 Ω) SWCNT wide change (up 106 governed by percolated network cracked region. sensor response remains nearly...

Most studies concerning electric powered UAVs' performance are based on fixed-weight plane model for the fact that battery's weight remains unchanged during discharging. However, it is possible to extend endurance by dumping exhausted batteries out of aircraft in flight. Impact factors affecting UAV with battery-dumping capability such as battery system (BDS) ratio, mounting and device (BMDD) packs count strategy were studied discussed. The optimum conventional concept then obtained compared...

ABSTRACT The cycloidal propeller for a Micro-Aerial Vehicle (MAV)-scale cyclogyro in hover was studied using 2D Reynolds-averaged Navier-Stokes equations solver. effects of the blade dynamic stall, parallel Blade Vortex Interaction (BVI), inflow variation and flow curvature were discussed, based on results numerical simulation. from Computational Fluid Dynamics simulation indicated that rotor is actually performing pitching oscillation, if observed moving reference frame. stall vortices shed...

An effective unsteady aerodynamic-optimization method of airfoil for cycloidal propellers is developed. Firstly, the class-function/shape-function transformation parameterization adopted to describe profile with different geometrical parameters. Secondly, sample points in design space are selected using optimal Latin hypercube methodology. Thirdly, actual aerodynamic performance simulated by time-dependent incompressible Reynolds-averaged Navier–Stokes computational fluid dynamics and...

In recent years, a lot of research work has been carried out on the cycloidal rotors. However, it lacks thorough understanding about effects blade platform shape hover efficiency rotor, and knowledge how to design blades. This paper presents numerical simulation model based Unsteady Reynolds-Averaged Navier–Stokes equations (URANSs), which is further validated by experimental results. The aspect ratio taper are analyzed, shows that rotors with same chord length have quite similar performance...

The aerodynamics of a cycloidal propeller operating in hovering flight is systematically studied using numerical method. By solving the time-dependent incompressible Navier–Stokes equations and dynamic mesh technique, complex unsteady flow field around time-varying aerodynamic forces are investigated. wake deflection can be observed propeller, which results thrust. Strong downwash interference between blades induced by rotation pitch motion blade. instantaneous vertical, horizontal resultant...

A new unsteady three-dimensional aerodynamic performance prediction approach is established to achieve fast and accurate of the aerodynamics cycloidal propellers. This model developed by coupling momentum theory, lifting-line method, free wake model, Leishman–Beddoes semi-empirical dynamic stall model. The overall calculation process includes two parts. Firstly, reduce computational time improve convergence, theory coupled with predict a uniform inflow velocity through propeller disc, which...

The cycloidal propellers for MAV scale cyclogyro with flat plate airfoil in hovering status are studied this paper. results from CFD computation and the experiments match well. simulation is based on moving mesh RANS. indicates that there leading edge vortex trailing due to blade dynamic stall. Intense interaction between vortices shed upstream downstream observed. will either cause drop force coefficients or induce upwash enhance vortex. then large coefficient peaks. also can delay stall of...

Purpose This paper aims to investigate the mechanisms lying behind cycloidal rotor under hovering status.

This paper introduces the basic theory and method of compressed sensing, its application in DOA estimation. The uses a new sampling through sparse reconstruction signal to break limitation Nyquist theorem, effectively solving inherent shortcomings classic spatial spectrum estimation algorithms.

The cycloidal propellers for MAV scale cyclocopter in hovering status were studied this paper based on the URANs solver using 2D, 2.5D, 3D half blade and full model. results from all numerical models validated with experimental results. It was found that 2.5D model cannot produce more accurate than 2D model, hence employed to discuss rotor infinite span. also indicates produces same as but is efficient simulation of finite (3D model) span (2D compared. indicated large pitching amplitude,...

The cycloidal propellers for micro aerial vehicle scale cyclocopter in hovering status were studied this paper based on the URANs solver using 2D, 2.5D, 3D half blade and full model. results from all numerical models validated with experimental results. It was found that 2.5D model cannot produce more accurate than 2D model, hence employed to discuss rotor infinite span. also indicated produced same as but efficient simulation of finite (3D model) span (2D compared. large pitching amplitude,...

The numerical simulations for cycloidal propellers based on five airfoils with different thickness are presented in this paper. CFD simulation is sliding mesh and URANS. result of indicates that all test cases share similar flow pattern. There leading edge vortex trailing due to blade dynamic stall. Interaction between the vortices shed from upstream downstream observed. also variation velocity encountered by downwash rotor cage. These factors large fluctuations aerodynamics forces blade....

Cycloidal rotor is a whose blades pitch around the pitching axis and revolve shaft that parallel to blade. It can generate omni-directional thrust with high efficiency. In this paper, numerical simulation models were validated by wind tunnel experiments. Then physics of cycloidal in forward flight was studied. The effects blade number advance ratio qualitatively discussed based on results. Results analysis indicate more will result smoother force curve, so there be lower vibration. However,...

Purpose This paper aims to investigate the impact of aerofoil camber on performance micro-air-vehicle-scale cycloidal propellers. Design/methodology/approach First, experiments were conducted validate numerical methodology. After that, three turbulent models compared select most accurate one. Then, 2D simulation was carried out 11 aerofoils with different cambers, including five cambered aerofoils, one symmetrical and inverse aerofoils. The are about chord line corresponding ones. Findings...

Abstract Consider material machinability and lattice mismatch sapphire as substrates for the ultraviolet-C light-emitting diodes (UV-C LEDs) are commonly used, but their high refractive index can result in total internal reflection (TIR) of light whereby some is absorbed, therefore caused reducing extraction efficiency (LEE). In this study, we propose a method to optimize thickness substrate guide layer through first-order optical design which used simulation software Ansys SPEOS simulate...