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Investigation of the nonlinear static and dynamic behaviour of rectangular microplates under electrostatic actuation
摘要： We present an investigation of the static and dynamic behavior of the nonlinear von-Karman plates when actuated by the nonlinear electrostatic forces. The investigation is based on a reduced order model developed using the Galerkin method, which rely on modeshapes and in-plane shape functions extracted using a finite element method. In this study, a fully clamped microplate is considered. We investigate the static behavior and the results are validated by comparison with the results calculated by a finite element model. The forced-vibration response of the plate is then investigated when the plate is excited by a harmonic AC load superimposed to a DC load. The dynamic behavior is examined near the primary resonance. The microplate shows a strong hardening behavior due to the cubic nonlinearity of mid-plane stretching. However, the behavior switches to softening as the DC load is increased.
关键词： Galerkin method,nonlinear von-Karman plates,reduced order model,dynamic behavior,finite element method,softening behavior,static behavior,hardening behavior,electrostatic forces,microplate
更新于2025-09-04 15:30:14
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Band-fluctuations model for the fundamental absorption of crystalline and amorphous semiconductors: a dimensionless joint density of states analysis
摘要： We develop a band-fluctuations model which describes the absorption coefficient in the fundamental absorption region for direct and indirect electronic transitions in disordered semiconductor materials. The model accurately describes both the Urbach tail and absorption edge regions observed in such materials near the mobility edge in a single equation with only three fitting parameters. An asymptotic analysis leads to the universally observed exponential tail below the bandgap energy and to the absorption edge model at zero Kelvin above it, for either direct or indirect electronic transitions. The latter feature allows the discrimination between the absorption edge and absorption tails, thus yielding more accurate bandgap values when fitting optical absorption data. We examine the general character of the model using a dimensionless Joint Density of States formalism with a quantitative analysis of a large amount of optical absorption data. Both heavily doped p-type GaAs and nano-crystalline Ga1?xMnxN, as examples for direct bandgap materials, as well as amorphous Si:Hx, SiC:Hx and SiNx, are modeled successfully with this approach. We contrast our model with previously reported empirical models, showing in our case a suitable absorption coefficient shape capable of describing various distinct materials while also maintaining the universality of the exponential absorption tail and absorption edge.
关键词： band-fluctuations model,fundamental absorption,disordered semiconductor materials,absorption edge,Joint Density of States,Urbach tail
更新于2025-09-04 15:30:14
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Perturbation approach for computing frequency- and time-resolved photon correlation functions
摘要： We propose an alternative formulation of the sensor method presented in Phys. Rev. Lett. 109, 183601 (2012) for the calculation of frequency-?ltered and time-resolved photon correlations. Our approach is based on an algebraic expansion of the joint steady state of quantum emitter and sensors with respect to the emitter-sensor coupling parameter (cid:2). This allows us to express photon correlations in terms of the open quantum dynamics of the emitting system only and ensures that computation of correlations are independent on the choice of a small value of (cid:2). Moreover, using time-dependent perturbation theory, we are able to express the frequency- and time-resolved second-order photon correlation as the addition of three components, each of which gives insight into the physical processes dominating the correlation at different time scales. We consider a bioinspired vibronic dimer model to illustrate the agreement between the original formulation and our approach.
关键词： vibronic dimer model,time-resolved photon correlations,quantum emitter,photon correlation functions,sensor method
更新于2025-09-04 15:30:14
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Photocontrol of magnetic structure in an itinerant magnet
摘要： We study the photoinduced magnetic transition in an itinerant magnet described by the double-exchange model, in which conduction electrons couple with localized spins through the ferromagnetic (FM) Hund coupling. It is shown that intense light applied to the FM ground state induces an antiferromagnetic (AFM) order, in contrast to the AFM-to-FM transition due to the photocarrier injection. In particular, we focus on the mechanism for instability of the FM structure by the light irradiation. The magnon spectrum in the Floquet state is formulated on the basis of the perturbative expansion of the Floquet Green’s function. The magnon dispersion shows softening at momentum (π, π ) in the square lattice with increasing the light amplitude, implying photoinduced AFM instability. This result is mainly attributed to a nonequilibrium electron distribution, which promotes low-energy Stoner excitations. The transient optical conductivity spectra characterized by interband excitations and Floquet sidepeaks are available to identify the photoinduced AFM state.
关键词： photoinduced magnetic transition,magnon spectrum,double-exchange model,itinerant magnet,optical conductivity,Floquet state
更新于2025-09-04 15:30:14
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Fast 3D reconstruction of dental cast model based on structured light
摘要： To quickly obtain accurate 3D data of dental cast model, this paper proposes a 3D reconstruction method for dental cast model based on structured light. This method combines the structured light with the motor turntable to obtain a group of 3D data for the dental cast model from multiple angles, and automatically registers the dental 3D data from multiple angles through the ball calibration of turntable. Compared with the real data of the dental cast model, the maximum error of the 3D reconstruction results in this paper is 0.115 mm. The reconstruction time of this process is about 130 s. The experimental results show that the method has high precision and high scanning speed for the 3D reconstruction of the dental cast model.
关键词： ball calibration,structured light,motor turntable,dental cast model,3D reconstruction
更新于2025-09-04 15:30:14
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[IEEE 2018 7th International Conference on Renewable Energy Research and Applications (ICRERA) - Paris, France (2018.10.14-2018.10.17)] 2018 7th International Conference on Renewable Energy Research and Applications (ICRERA) - Application of Model Predictive Control in Modular Multilevel Converters for MTPA Operation and reduced Switching Losses
摘要： In this paper, a one-step Model Predictive Control system is executed in the Multilevel modular converter (MMC) to control the speed of an Interior Permanent Magnet (IPM) machine. Maximum Torque per Ampere (MTPA) and Field Weakening (FW) control technique is utilized for the greatest yield torque. The proposed Control strategy tracks the reference produced by MTPA and FW calculation by freely directing voltages from the MMC modules. The proposed method also studies the relation between the switching losses of MOSFETs and sampling frequency, cost function and a number of modules in an MMC. Finally, simulation results are provided to demonstrate the appropriateness of this control procedure.
关键词： Model Predictive Control,Modular Multilevel Converter (MPC),Maximum Torque per Ampere (MTPA),Interior Permanent Magnet motor (IPM),Switching losses,Field Weakening (FW)
更新于2025-09-04 15:30:14
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[IEEE 2018 7th International Conference on Renewable Energy Research and Applications (ICRERA) - Paris, France (2018.10.14-2018.10.17)] 2018 7th International Conference on Renewable Energy Research and Applications (ICRERA) - From Solar Microgrid Simulation to Field Deployment: Accuracy and Uncertainties
摘要： Economical, stand-alone, solar microgrids can be quickly implemented in most un-electrified regions of the world. Solar resource maps developed by the National Aeronautics and Space Administration (NASA) and the National Renewable Energy Laboratory (NREL), together with HOMER Pro software, have been widely used to determine the optimal design of microgrids. Repercussions of imprecise predictions of solar resources and electrical power generation lead to an increased likelihood of energy shortage in a stand-alone microgrid, or increases overall project costs. Actual solar energy productions of two sites in Kerala, India, were compared with solar electricity generation, predicted by the HOMER Pro tool. For both test sites, the results showed that the simulated, solar production was within 8.1% of the actual annual production. However, monthly variations in solar production led to unanticipated energy shortages in the simulated microgrids. These findings reaffirm the inexorable need of the following actions for cost-effective design of microgrids: a) systematic analysis of reliability of electrical supply, and b) deployment of schemes for demand response and flexible load. Statistical analysis of temporal variation of solar irradiance in the United States were used to inform recommendations for stand-alone microgrid design.
关键词： accuracy,HOMER,solar,resource,model,microgrid,design
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Intelligent Transportation Systems (ITSC) - Maui, HI, USA (2018.11.4-2018.11.7)] 2018 21st International Conference on Intelligent Transportation Systems (ITSC) - Automotive Radar Multipath Propagation in Uncertain Environments
摘要： Future use of high-resolution near range radar sensors for vehicle environment perception is facing challenges in terms of detection and correct assignment of multipath reflections (false-positives) from surfaces and obstacles. This paper presents a novel geometric model to determine the relative positions from surrounding targets and reflection surfaces assuming that every object moves on a circular path to a mutual center. Principles of electromagnetic wave propagation under consideration of incident wave angles at potential reflection surfaces are described. Radar measurements illuminating an experimental target and a highway barrier as reflection surface, which reproducibly generates several multipath reflections, were carried out in a deterministic test environment and validate our presented methods. The installation of absorption material at intense reflection areas was conducted as countermeasure to reduce the intensity of false-positive detections. Furthermore, a realistic urban driving scenario using a real vehicle as target object and a building wall was reconstructed to proof field relevance.
关键词： electromagnetic wave propagation,false-positive detections,multipath propagation,Automotive radar,geometric model
更新于2025-09-04 15:30:14
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Model of GaSb-InAs p-i-n Gate All Around (GAA) BioTunnel FET (BTFET)
摘要： The paper investigates the role of hetero-Junction (HJ) p-i-n Gate All Around GAA Tunnel FET architecture for biosensing applications. The device offers better sensitivity and has been modeled in terms of various parameters such as surface potential, threshold voltage and drain current. Analytical modeling scheme relates to the exact resultant solution of two-dimensional Poisson equation. The shift in the threshold voltage has been considered as the sensing parameter to detect the sensitivity when the biomolecules are immobilized in the cavity region.
关键词： Gate all around tunnel FET (GAA-TFET),Model,Bio-Sensor,Hetero Junction (HJ),Dielectric Modulation
更新于2025-09-04 15:30:14
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Error-Splitting Forward Model for Iterative Reconstruction in X-ray Computed Tomography and application with Gauss-Markov-Potts prior
摘要： In order to enhance image quality for controlling the interior of a volume in industry, model-based iterative reconstruction (MBIR) methods in 3D X-ray Computed Tomography (CT) have shown their efficiency compared to analytical reconstruction methods. MBIR methods enforce a prior model on the volume to reconstruct and make fusion of the information contained in the prior model and the projection data. The projections have many uncertainties which have very different origins in 3D CT. They are taken into account in MBIR methods but, despite of their different origins, they are in general gathered in only one term in the forward model. In this paper, we propose to derive a new forward model by adding a further error term in the Poisson statistics of photon-count, corresponding to the deviation of the monochromatic model with respect to the actual polychromacy of the rays. A Taylor expansion of the Poisson log-likelihood leads us to a new algebraic forward model accounting for two terms of uncertainties : we call it the error-splitting forward model. Different prior models are assigned to each of distinguished uncertainties : measurement uncertainties are modeled as Gaussian, while linear model uncertainties are modeled as heavy-tailed to bring robustness to the reconstruction process. We give strategies to fix the parameters of the error-splitting forward model. Next, we use it in a full MBIR method with Gauss-Markov-Potts prior model on the volume, in order to reconstruct piecewise-constant objects for non-destructive testing in industry. Compared to the conventional forward model, we show in our experiments that the use of the error-splitting forward model with Gauss-Markov-Potts prior combines better robustness and accuracy.
关键词： 3D Computed Tomography,iterative reconstruction,Gauss-Markov-Potts,error-splitting,forward model,Bayesian approach,non-destructive testing
更新于2025-09-04 15:30:14