8,139 research outputs found

    Compact Model Representation for 3D Reconstruction

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    3D reconstruction from 2D images is a central problem in computer vision. Recent works have been focusing on reconstruction directly from a single image. It is well known however that only one image cannot provide enough information for such a reconstruction. A prior knowledge that has been entertained are 3D CAD models due to its online ubiquity. A fundamental question is how to compactly represent millions of CAD models while allowing generalization to new unseen objects with fine-scaled geometry. We introduce an approach to compactly represent a 3D mesh. Our method first selects a 3D model from a graph structure by using a novel free-form deformation FFD 3D-2D registration, and then the selected 3D model is refined to best fit the image silhouette. We perform a comprehensive quantitative and qualitative analysis that demonstrates impressive dense and realistic 3D reconstruction from single images.Comment: 9 pages, 6 figure

    Consistency of compact and extended models of glucose-insulin homeostasis: The role of variable pancreatic reserve

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    Published compact and extended models of the glucose-insulin physiologic control system are compared, in order to understand why a specific functional form of the compact model proved to be necessary for a satisfactory representation of acute perturbation experiments such as the Intra Venous Glucose Tolerance Test (IVGTT). A spectrum of IVGTT’s of virtual subjects ranging from normal to IFG to IGT to frank T2DM were simulated using an extended model incorporating the population-of-controllers paradigm originally hypothesized by Grodsky, and proven to be able to capture a wide array of experimental results from heterogeneous perturbation procedures. The simulated IVGTT’s were then fitted with the Single-Delay Model (SDM), a compact model with only six free parameters, previously shown to be very effective in delivering precise estimates of insulin sensitivity and secretion during an IVGTT. Comparison of the generating, extended-model parameter values with the obtained compact model estimates shows that the functional form of the nonlinear insulin-secretion term, empirically found to be necessary for the compact model to satisfactorily fit clinical observations, captures the pancreatic reserve level of the simulated virtual patients. This result supports the validity of the compact model as a meaningful analysis tool for the clinical assessment of insulin sensitivity

    Compact Model for Multiple Independent Gates Ambipolar Devices

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    The model presented is a charge-based model that assures the continuity of the current and the analytical derivability of charges to obtain the parasitic capacitances. It has been conceived to support the multiple independent gates, typical of nano-array structures, where each gate controls the charge in the channel. Charge conservation implies constant current in the different section of the multiple gate nanowire FET, making possible the development of a compact model for an arbitrary number of gates. The model has been used to describe different structures (i.e. number of gates, dimension of the single transistor and ranges of applied voltages) under static conditions and the results have been verified on Silvaco TCAD simulations. The modeling approach and the attained results for some cases of study will be presented and discusse

    Criticality of compact and noncompact quantum dissipative Z4Z_4 models in (1+1)(1+1) dimensions

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    Using large-scale Monte Carlo computations, we study two versions of a (1+1)D(1+1)D Z4Z_4-symmetric model with Ohmic bond dissipation. In one of these versions, the variables are restricted to the interval [0,2π>[0,2\pi>, while the domain is unrestricted in the other version. The compact model features a completely ordered phase with a broken Z4Z_4 symmetry and a disordered phase, separated by a critical line. The noncompact model features three phases. In addition to the two phases exhibited by the compact model, there is also an intermediate phase with isotropic quasi-long-range order. We calculate the dynamical critical exponent zz along the critical lines of both models to see if the compactness of the variable is relevant to the critical scaling between space and imaginary time. There appears to be no difference between the two models in that respect, and we find z≈1z\approx1 for the single phase transition in the compact model as well as for both transitions in the noncompact model

    A GaN-HEMT compact model including dynamic r<sub>DSon</sub> effect for power electronics converters

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    In order to model GaN-HEMT switching transients and determine power losses, a compact model including dynamic RDSon effect is proposed herein. The model includes mathematical equations to represent device static and capacitance-voltage characteristics, and a behavioural voltage source, which includes multiple RC units to represent different time constants for trapping and detrapping effect from 100 ns to 100 s range. All the required parameters in the model can be obtained by fitting method using a datasheet or experimental characterisation results. The model is then implemented into our developed virtual prototyping software, where the device compact model is co-simulated with a parasitic inductance physical model to obtain the switching waveform. As model order reduction is applied in our software to resolve physical model, the device switching current and voltage waveform can be obtained in the range of minutes. By comparison with experimental measurements, the model is validated to accurately represent device switching transients as well as their spectrum in frequency domain until 100 MHz. In terms of dynamic RDSon value, the mismatch between the model and experimental results is within 10% under different power converter operation conditions in terms of switching frequencies and duty cycles, so designers can use this model to accurately obtain GaN-HEMT power losses due to trapping and detrapping effects for power electronics converters

    Integrating 'atomistic', intrinsic parameter fluctuations into compact model circuit analysis

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    MOSFET parameter fluctuations, resulting from the 'atomistic' granular nature of matter, are predicted to be a critical roadblock to the scaling of devices in future electronic systems. A methodology is presented which allows compact model based circuit analysis tools to exploit the results of 'atomistic' device simulation, allowing investigation of the effects of such fluctuations on circuits and systems. The methodology is applied to a CMOS inverter, ring oscillator, and analogue NMOS current mirror as simple initial examples of its efficacy

    Canonical D = 1 supergravity framework for FLRW cosmology

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    We construct an extension of standard flat FLRW cosmology with matter, possessing local D = 1, N = 1 proper-time supersymmetry. The fundamental equation for the resulting mini-superspace models of quantum universes is a Dirac-like analogue of the Friedmann and Wheeler-DeWitt equations. We provide solutions of this equation for specific matter configurations based on the supersymmetric O(3) and O(2, 1) sigma-models. It turns out that in the compact model the volume rate of growth of the universe is quantized and non-vanishing due to the zero-point energy of the scalar fields. In the non-compact model the spectrum of the growth rates is continuous but subject to an uncertainty relation involving the scale and the growth factor.Comment: 14 pages, no figure
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