To fulfill the sustainability need of today’s comfort conscious consumers, an attempt has been made in this research study to explore the possibilities of producing high-quality apparel fabrics using unconventional f...To fulfill the sustainability need of today’s comfort conscious consumers, an attempt has been made in this research study to explore the possibilities of producing high-quality apparel fabrics using unconventional fiber fabrics and their union fabrics. Unconventional natural fibers such as banana, hemp, linen and ramie and also their union fabrics with cotton were used. Union fabrics have different fiber content in warp and weft directions. A comparative study was made on the comfort behavior of these fabrics to evaluate their comfort performance. The properties of these fabrics were evaluated and compared under air permeability, moisture management, thermal properties, low-stress mechanical properties, etc. Unconventional fiber fabrics showed better results in many cases and thus were comparable with 100% cotton fabrics.展开更多
Hovering ability forms the basis for space operations of Micro Aerial Vehicles(MAVs).The problem of uneven load puts high demands on the wing design.In this paper,a new hovering-mode for MAVs,inspired by flapping flig...Hovering ability forms the basis for space operations of Micro Aerial Vehicles(MAVs).The problem of uneven load puts high demands on the wing design.In this paper,a new hovering-mode for MAVs,inspired by flapping flight in bees and hummingbirds but using high-aspect-ratio and low-stress wings,is proposed.Different from the flapping actuations that occur at the wing roots,the two wings are driven back and forth in a straight line.To simplify the design and control the angle of attack,passive wing rotation is employed.The numerical results and analysis show that the maximum stress of the oscillating wing is approximately 1/6 of that of the flapping wing when the lift of the oscillating wing is twice that of the flapping wing.A theoretical aerodynamic model of the kinematics of the vehicle's driving mechanism was developed to fulfill its design.Force measurements indicate that the vehicle generates a sufficiently high cycle-averaged vertical thrust(71 g)for liftoff at a maximum frequency of 5.56 Hz,thereby validating the proposed aerodynamic model.Moreover,liftoff performance is presented to visually demonstrate the vertical take-off capabilities and hovering potential of the aeromechanical solution.展开更多
文摘To fulfill the sustainability need of today’s comfort conscious consumers, an attempt has been made in this research study to explore the possibilities of producing high-quality apparel fabrics using unconventional fiber fabrics and their union fabrics. Unconventional natural fibers such as banana, hemp, linen and ramie and also their union fabrics with cotton were used. Union fabrics have different fiber content in warp and weft directions. A comparative study was made on the comfort behavior of these fabrics to evaluate their comfort performance. The properties of these fabrics were evaluated and compared under air permeability, moisture management, thermal properties, low-stress mechanical properties, etc. Unconventional fiber fabrics showed better results in many cases and thus were comparable with 100% cotton fabrics.
基金This work was supported by the National Natural Science Foundation of China(No.91960203).
文摘Hovering ability forms the basis for space operations of Micro Aerial Vehicles(MAVs).The problem of uneven load puts high demands on the wing design.In this paper,a new hovering-mode for MAVs,inspired by flapping flight in bees and hummingbirds but using high-aspect-ratio and low-stress wings,is proposed.Different from the flapping actuations that occur at the wing roots,the two wings are driven back and forth in a straight line.To simplify the design and control the angle of attack,passive wing rotation is employed.The numerical results and analysis show that the maximum stress of the oscillating wing is approximately 1/6 of that of the flapping wing when the lift of the oscillating wing is twice that of the flapping wing.A theoretical aerodynamic model of the kinematics of the vehicle's driving mechanism was developed to fulfill its design.Force measurements indicate that the vehicle generates a sufficiently high cycle-averaged vertical thrust(71 g)for liftoff at a maximum frequency of 5.56 Hz,thereby validating the proposed aerodynamic model.Moreover,liftoff performance is presented to visually demonstrate the vertical take-off capabilities and hovering potential of the aeromechanical solution.
