Mechanism and experiments of asymmetrical pitch system for MAV
In view of problem for miniaturizing Micro Air Vehicles (MAV), a novel asymmetrical pitch system faced to rotary wing MAV is introduced. The pitch mechanism and control characteristics are studied and analyzed. Because the deformation of elasticity link is key to generate the blade pitch, it is analyzed and calculated by elasticity finite element method. And the results illustrate the linear relationship between blade pitch angles and the output torque of the motor. Based on control system of asymmetrical pitch, mechanism experiments based on strain gauge are done, and the factors that affect the deformation of the elastic linkage is analyzed. Results indicate that mechanism of asymmetrical pitch is effective.
Analysis of rotor manipulation mechanism for unmanned micro helicopters
The small size and low carrying capacity of unmanned micro helicopters requires a rotor manipulation mechanism that makes use of the rotor inertia and material elasticity and meets the requirement of the helicopter flying mode control. The mechanism quickly follows changes of the motor output moment. The equation for the rotor blade lag was derived using the Hamilton principle and solved using the extended Galerkin method. The blade lagging motion for the condition of varying angular velocities was analyzed. The results illustrate how the radius of the rigid center body and the various angular accelerations of the rotor affect the blade displacements and how the initial angular velocity of the rotor affects the blade lag frequency.
Phase diagram and magnetic properties of the diluted fcc system NipMg1-pO.
Starting from Ni and Mg nitrates, about 20 samples of ${\mathrm{Ni}}_{\mathit{p}}$${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$O samples (with 0.06\ensuremath{\le}p\ensuremath{\le}0.86) were prepared and x-ray-diffraction studies showed the samples to have the NaCl structure with the lattice constant fitting the expression a(p)=4.2115-0.0340p \AA{}. Temperature-dependent magnetic-susceptibility (\ensuremath{\chi}) studies of the samples were carried out between 1.8 and 600 K using a superconducting-quantum-interference-device magnetometer and N\'eel temperatures ${\mathit{T}}_{\mathit{N}}$'s were determined from the peak in \ensuremath{\partial}(\ensuremath{\chi}T)/\ensuremath{\partial}T. The variation of t=${\mathit{T}}_{\mathit{N}}$(p)/${\mathit{T}}_{\mathit{N}}$(1) vs p is compared with that of ${\mathrm{Co}}_{\mathit{p}}$${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$O. For both systems, the variations for pg0.31 are found to fit the predicted values for a simple-cubic Heisenberg antiferromagnet and a theoretical basis for this anomalous result is advanced. The experimental percolation threshold ${\mathit{p}}_{\mathit{c}}$=0.15\ifmmode\pm\else\textpm\fi{}0.01 and for ${\mathit{p}}_{\mathit{c}}$p0.31, \ensuremath{\chi} below ${\mathit{T}}_{\mathit{N}}$ shows irreversible behavior for the zero-field-cooled and field-cooled cases, suggestive of spin-glass-like behavior also observed in other diluted fcc antiferromagnets, such as ${\mathrm{Co}}_{\mathit{p}}$${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$O and ${\mathrm{Eu}}_{\mathit{p}}$${\mathrm{Sr}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$Te. It is suggested that the differences in the t-vs-p variations for p0.31 in ${\mathrm{Ni}}_{\mathit{p}}$${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$O, ${\mathrm{Co}}_{\mathit{p}}$${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$O, and ${\mathrm{Eu}}_{\mathit{p}}$${\mathrm{Sr}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$Te may be related to the differences in the ratio of the next-nearest-neighbor to nearest-neighbor exchange constants in these systems.