397 research outputs found
Reversible Transition Between Thermodynamically Stable Phases with Low Density of Oxygen Vacancies on SrTiO(110) Surface
The surface reconstruction of SrTiO(110) is studied with scanning
tunneling microscopy and density functional theory (DFT) calculations. The
reversible phase transition between (41) and (51) is controlled
by adjusting the surface metal concentration [Sr] or [Ti]. Resolving the atomic
structures of the surface, DFT calculations verify that the phase stability
changes upon the chemical potential of Sr or Ti. Particularly, the density of
oxygen vacancies is low on the thermodynamically stabilized SrTiO(110)
surface.Comment: Accepted by Physical Review Letter
A distributed and low-order GPS/SINS algorithm of flight parameters estimation for unmanned vehicle
A distributed, low-order and highly efficient strapdown navigation algorithm is developed to estimate the real flight parameters for flight control system. Firstly, the attitude estimation Kalman filter is designed according to the relationship between angular and angular rate. Then, the measured angular rate is compensated by solving the drift noise of gyro. Furthermore, the accuracy of attitude is improved by compensating the accelerometer of the rigid body from differential velocity of GPS. Secondly, the improved attitude is used as an input into the filter algorithms of velocity and position by using the concept of distributed Kalman filter, which reducing the order of Kalman filter effectively. The velocity and position filter algorithms, which provide smooth feedback parameters for control system, are developed based on the rigid body dynamic equations and GPS parameters. Finally, the numerical simulation indicates that the attitude provided by attitude Kalman filter is of high accuracy in flight condition, and the performance of the attitude velocity and position algorithms are verified by flight tests of a small unmanned tiltrotor
Devices for surface working by plane means of vibration rolling
The analysis of manufacturing and technology accessories for regular micro-relief forming at
flat surfaces by vibration rolling is given. The new design of apparatus providing an equal
vibration roling forces at all vibration rolling devices is proposed
A low temperature disordered phase of alpha-Pb/Ge(111)
A new structural phase transition has been observed at low temperatures for
the one third of a monolayer (alpha phase) of Pb on Ge(111) using a
variable-temperature scanning tunneling microscope. The well-known (r3xr3)R30
to (3x3) transition is accompanied by a new structural phase transition from
(3x3) to a disordered phase at ~76 K. The formation of the new disordered phase
is incompatible with the belief that the (3x3) phase is the ground state. The
mechanism of the phase transition in this triangular lattice can be mapped onto
antiferromagnetic spin Ising model, with the geometric frustration.Comment: 4 pages, 3 figure
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