417 research outputs found
Atomic-state diagnostics and optimization in cold-atom experiments
We report on the creation, observation and optimization of superposition
states of cold atoms. In our experiments, rubidium atoms are prepared in a
magneto-optical trap and later, after switching off the trapping fields,
Faraday rotation of a weak probe beam is used to characterize atomic states
prepared by application of appropriate light pulses and external magnetic
fields. We discuss the signatures of polarization and alignment of atomic spin
states and identify main factors responsible for deterioration of the atomic
number and their coherence and present means for their optimization, like
relaxation in the dark with the strobe probing. These results may be used for
controlled preparation of cold atom samples and in situ magnetometry of static
and transient fieldsComment: 15 pages and 9 figures (including supplementary information
Role of the molybdenum addition on the mechanical properties and structure of the NiCoMnIn alloys
In this paper, the influence of Mo addition on the structure and mechanical properties of the NiCoMnIn alloys have been studied. Series of polycrystalline NiCoMnIn alloys containing from 0 to 5 mas.% of Mo were produced by the arc melting technique. For the alloys containing Mo, two-phase microstructure was observed. Mo-rich precipitates were distributed randomly in the matrix. The relative volume fraction of the precipitates depends on the Mo content. The numbers of the Mo rich precipitates increases with the Mo contents. The structures of the phases were determined by the TEM. The mechanical properties of the alloys are strongly affected by Mo addition contents. Brittleness of the alloys increases with the Mo contents
Neural Network Contour Error Predictor in CNC Control Systems
Paper presented as poster presentation at MMAR 2016 conference (Międzyzdroje,Poland, 29 Aug.-1 Sept. 2016)This article presents a method for predicting contour error using artificial neural networks. Contour error is defined as the minimum distance between actual position and reference toolpath and is commonly used to measure machining precision of Computerized Numerically Controlled (CNC) machine tools. Offline trained Nonlinear Autoregressive networks with exogenous inputs (NARX) are used to predict following error in each axis. These values and information about toolpath geometry obtained from the interpolator are then used to compute the contour error. The method used for effective off-line training of the dynamic recurrent NARX neural networks is presented. Tests are performed that verify the contour error prediction accuracy using a biaxial CNC machine in a real-time CNC control system. The presented neural network based contour error predictor was used in a predictive feedrate optimization algorithm with constrained contour error
Topological Mott insulator in odd-integer filled Anderson lattice model with Hatsugai-Kohmoto interactions
Recently, quantum anomalous Hall state at odd integer filling in moir\'e
stacked MoTe/WSe has been convincingly interpreted as a topological
Mott insulator state appearing due to strong interactions in {\it band} basis
[arXiv:2210.11486]. In this work, we aim to analyze the formation of a
topological Mott insulator due to interactions in {\it orbital} basis instead,
being more natural for systems where interactions originate from the character
of or orbitals rather than band flatness. For that reason, we study an
odd-integer filled Anderson lattice model incorporating odd-parity
hybridization between orbitals with different degrees of correlations
introduced in the Hatsugai-Kohmoto spirit. We demonstrate that a topological
Mott insulating state can be realized in a considered model only when weak
intra- and inter-orbital correlations involving dispersive states are taken
into account. Interestingly, we find that all topological transitions between
trivial and topological Mott insulating phases are not
accompanied by a spectral gap closing, consistently with a phenomenon called
{\it first-order topological transition}. Instead, they are signaled by a kink
developed in spectral function at one of the time reversal invariant momenta.
We believe that our approach can provide insightful phenomenology of
topological Mott insulators in spin-orbit coupled or electron systems.Comment: 7 pages, 4 fig
PSO based feedrate optimization with contour error constraints for NURBS toolpaths
Paper presented at MMAR 2016 conference (Międzyzdroje, Poland, 29 Aug.-1 Sept. 2016)Generation of a time-optimal feedrate profile for CNC machines has received significant attention in recent years. Most methods focus on achieving maximum allowable feedrate with constrained axial acceleration and jerk without considering manufacturing precision. Manufacturing precision is often defined as contour error which is the distance between desired and actual toolpaths. This paper presents a method of determining the maximum feedrate for NURBS toolpaths while constraining velocity, acceleration, jerk and contour error. Contour error is predicted during optimization by using an artificial neural-network. Optimization is performed by Particle Swarm Optimization with Augmented Lagrangian constraint handling technique. Results of a time-optimal feedrate profile generated for an example toolpath are presented to illustrate the capabilities of the proposed method
Correlation of eigenstates in the critical regime of quantum Hall systems
We extend the multifractal analysis of the statistics of critical wave
functions in quantum Hall systems by calculating numerically the correlations
of local amplitudes corresponding to eigenstates at two different energies. Our
results confirm multifractal scaling relations which are different from those
occurring in conventional critical phenomena. The critical exponent
corresponding to the typical amplitude, , gives an almost
complete characterization of the critical behavior of eigenstates, including
correlations. Our results support the interpretation of the local density of
states being an order parameter of the Anderson transition.Comment: 17 pages, 9 Postscript figure
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