322 research outputs found
A Gyro Signal Characteristics Analysis Method Based on Empirical Mode Decomposition
It is difficult to analyze the nonstationary gyro signal in detail for the Allan variance (AV) analysis method. A novel approach in the time-frequency domain for gyro signal characteristics analysis is proposed based on the empirical mode decomposition and Allan variance (EMDAV). The output signal of gyro is decomposed by empirical mode decomposition (EMD) first, and then the decomposed signal is analyzed by AV algorithm. Consequently, the gyro noise characteristics are demonstrated in the time-frequency domain with a three-dimensional (3D) manner. Practical data of fiber optic gyro (FOG) and MEMS gyro are processed by the AV method and the EMDAV algorithm separately. The results indicate that the details of gyro signal characteristics in different frequency bands can be described with the help of EMDAV, and the analysis dimensions are extended compared with the common AV. The proposed EMDAV, as a complementary tool of the AV, which provides a theoretical reference for the gyro signal preprocessing, is a general approach for the analysis and evaluation of gyro performance
Many-Objective Evolutionary Algorithm with Vector Angle Selection and Indicator Deletion
Given that the challenge for evolutionary algorithms when solving many-objective optimization problems lies in balancing the convergence and diversity, a many-objective evolutionary algorithm based on vector angle selection and indicator deletion (MOEA/AS-ID), is proposed. In this algorithm, a coordinated mechanism that includes two strategies is designed in the environmental selection process to delete the solutions with poor convergence and diversity one by one, retaining the elitist to participate in the evolution process for the next generation. To be specific, the former strategy based on vector angle selection is used to select a pair of solutions with a similar search direction in the objective space, and the latter indicator-based deletion strategy which uses the [ISDE+] indicator (indicator shift-based density estimation) that takes into account the convergence and diversity of a single solution, is employed to compare the selected pair of solutions and delete the solution with a smaller indicator value, then encourage the population to converge to the Pareto optimal front toward all directions. Finally, the balance between convergence and diversity of the solution set is achieved. On DTLZ (Deb-Thiele-Laumanns-Zitzler), SDTLZ (scaled DTLZ), and MaF (many-objective function) three benchmark test suites with various characteristics,MOEA/AS-ID and six recently proposed many-objective evolutionary algorithms covering all current types perform extensive comparative simulation experiments and numerical results analysis. Simulation results and numerical analysis show that MOEA/AS-ID has strong competitiveness in balancing the convergence and diversity when solving many-objective optimization problems with various characteristics
Interface-engineered hole doping in Sr2IrO4/LaNiO3 heterostructure
The relativistic Mott insulator Sr2IrO4 driven by large spin-orbit
interaction is known for the Jeff = 1/2 antiferromagnetic state which closely
resembles the electronic structure of parent compounds of superconducting
cuprates. Here, we report the realization of hole-doped Sr2IrO4 by means of
interfacial charge transfer in Sr2IrO4/LaNiO3 heterostructures. X-ray
photoelectron spectroscopy on Ir 4f edge along with the X-ray absorption
spectroscopy at Ni L2 edge confirmed that 5d electrons from Ir sites are
transferred onto Ni sites, leading to markedly electronic reconstruction at the
interface. Although the Sr2IrO4/LaNiO3 heterostructure remains non-metallic, we
reveal that the transport behavior is no longer described by the Mott variable
range hopping mode, but by the Efros-Shklovskii model. These findings highlight
a powerful utility of interfaces to realize emerging electronic states of the
Ruddlesden-Popper phases of Ir-based oxides.Comment: 9 pages including 3 figures and reference
Nanoscale Bandgap Tuning across an Inhomogeneous Ferroelectric Interface
We report nanoscale bandgap engineering via a local strain across the
inhomogeneous ferroelectric interface, which is controlled by the
visible-light-excited probe voltage. Switchable photovolatic effects and the
spectral response of the photocurrent were explore to illustrate the reversible
bandgap variation (~0.3eV). This local-strain-engineered bandgap has been
further revealed by in situ probe-voltage-assisted valence electron energy-loss
spectroscopy (EELS). Phase-field simulations and first-principle calculations
were also employed for illustration of the large local strain and the bandgap
variation in ferroelectric perovskite oxides. This reversible bandgap tuning in
complex oxides demonstrates a framework for the understanding of the
opticallyrelated behaviors (photovoltaic, photoemission, and photocatalyst
effects) affected by order parameters such as charge, orbital, and lattice
parameters
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