16,446 research outputs found
Ascent and descent of Gorenstein homological properties
Let be a ring homomorphism, where is a
commutative noetherian ring and is a finite -algebra. We give criteria
for detecting the ascent and descent of Gorenstein homological properties. As
an application, we get a result that supports a question of Avramov and Foxby.
We observe that the ascent and descent of Gorenstein homological property can
detect the Gorensein properties of rings along . Finally, we describe
when induces a triangle equivalence between the stable categories of
finitely generated Gorenstein projective modules.Comment: 21 pages, Any comments are welcome
Magnetic ordering of nitrogen-vacancy centers in diamond via resonator-mediated coupling
Nitrogen-vacancy centers in diamond, being a promising candidate for quantum
information processing, may also be an ideal platform for simulating many-body
physics. However, it is difficult to realize interactions between
nitrogen-vacancy centers strong enough to form a macroscopically ordered phase
under realistic temperatures. Here we propose a scheme to realize long-range
ferromagnetic Ising interactions between distant nitrogen-vacancy centers by
using a mechanical resonator as a medium. Since the critical temperature in the
long-range Ising model is proportional to the number of spins, a ferromagnetic
order can be formed at a temperature of tens of millikelvin for a sample with
nitrogen-vacancy centers. This method may provide a new platform for
studying many-body physics using qubit systems.Comment: 5 pages, 4 figure
Superradiance Lattice
We show that the timed Dicke states of a collection of three-level atoms can
form a tight-binding lattice in momentum space. This lattice, coined the
superradiance lattice (SL), can be constructed based on electromagnetically
induced transparency (EIT). For a one-dimensional SL, we need the coupling
field of the EIT system to be a standing wave. The detuning between the two
components of the standing wave introduces an effective uniform force in
momentum space. The quantum lattice dynamics, such as Bloch oscillations,
Wannier-Stark ladders, Bloch band collapsing and dynamic localization can be
observed in the SL. The two-dimensional SL provides a flexible platform for
Dirac physics in graphene. The SL can be extended to three and higher
dimensions where no analogous real space lattices exist with new physics
waiting to be explored.Comment: 6pages, 4 figure
Neutral network-PID control algorithm for semi-active suspensions with magneto-rheological damper
In this paper, a semi-active suspension control system based on Magneto-Rheological (MR) damper is designed for a commercial vehicle to improve the ride comfort and driving stability. A mathematical model of MR damper based on the Bouc-Wen hysteresis model is built. The mathematical model could precisely describe the characteristics of MR damper compared with the bench test results. The neural network-PID controller is designed for the semi-active suspension systems. According to the numerical results, the proposed controller can constrain vehicle vibrations and roll angle significantly. A detailed multi-body dynamic model of the light vehicle with four semi-active suspensions are established, and an actual vehicle handling and stability tests are carried out to verify the control performances of the proposed controller. It can be concluded that MR semi-active suspension systems can play a key role in coordination between the ride comfort and handling stability for the commercial vehicle
State estimation based on unscented Kalman filter for semi-active suspension systems
In this paper, a novel approach to estimate vehicle vibration state information in real time is proposed; it is based on unscented Kalman filter (UKF) theory. The UKF is based on the unscented transfer technique which considers high order terms during the measurement and update stage during the estimation. The proposed observer uses easily accessible measurements such as accelerations and suspension deflections to estimate the sprung and unspring mass vertical velocity for the suspension systems of full vehicle under unknown road disturbance. And it is with low sensitivity and robust to the unknown road surfaces. Matlab/Carsim co-simulation experiments are carried out to validate the performance of the estimator under two typical road excitations. The simulation results clearly indicate that the proposed UKF sate observer is precise
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