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Full capacitance model, considering the specifics of amorphous oxide semiconductor thin film transistors structures
摘要： A full capacitance model for Amorphous Oxide Semiconductor Thin Film Transistors (AOSTFTs), considering the effect of the drain contact overlap in bottom gate passivated structures is presented. It is shown that this drain overlap, on top of the passivation layer, serves as a second gate with an applied voltage equal to VDS. When VDS>VT the semiconductor-passivation (S-P) interface will be in accumulation and the behavior of the different capacitance is affected. An expression to represent this effect is included in the present model. The overlap capacitance between gate and drain/source, as well as the effect of reducing the channel capacitance as the drain is increased, are also considered by the model. The calculated capacitance is a function of the threshold voltage, (VT), the mobility and saturation parameters (γα,αs), and the sharpness of the knee region m, which are extracted using the Unified Model and Extraction Method (UMEM) for AOSTFTs. Results are compared with simulated and experimental data.
关键词： AOSTFT modeling,Capacitance model,Dynamic modeling
更新于2025-11-14 17:28:48
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Tailored nanocomposite energy harvesters with high piezoelectric voltage coefficient through controlled nanowire dispersion
摘要： Composites composed of piezoelectric nanomaterials dispersed in a flexible polymer have emerged as promising materials for highly durable and flexible energy harvesters and sensors. Although piezoelectric materials in their bulk form have a high electromechanical coupling coefficient and can efficiently convert mechanical energy to electrical energy, the ceramic form has low fracture toughness and thus they are limited in certain applications due to difficulty in machining and conforming to curved surfaces. Recently, additive manufacturing processes such as direct write, have been developed to incorporate piezoelectric nanowires into a polymer matrix with controlled alignment to realize printed piezoelectrics. Given the multiphase structure of a nanocomposite, it is possible to control the material structure such that the piezoelectric coupling and dielectric properties can be varied independently. In this paper, experimentally validated finite element (FE) and micromechanics models are developed for calculation and optimization of the piezoelectric voltage coefficient, g31, of a nanocomposite. It is shown that by using high aspect ratio nanowires with controlled alignment, the piezoelectric coupling can be disproportionately increased with respect to the dielectric constant which yields a g31 coefficient that can be enhanced more than seven times compared to the bulk piezoelectric material. Moreover, it is demonstrated that the use of high aspect ratio nanowires in the energy harvester resulted in significant improvement on the output electrical power of an energy harvester.
关键词： Energy harvesting,Nanowires,Finite element modeling (FEM),Voltage coefficient,Piezoelectric,The Mori-Tanaka method,Direct write,Nanocomposite
更新于2025-11-14 17:28:48
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Mesoporous TiO2-BiOBr Microspheres with Tailorable Adsorption Capacities for Photodegradation of Organic Water Pollutants: Probing Adsorption-Photocatalysis Synergy by Combining Experiments and Kinetic Modeling
摘要： Understanding adsorption-photocatalysis synergy helps advance solar-driven photodegradation of organic wastewater pollutants. To evaluate the synergy, mesoporous TiO2(amorphous)-BiOBr microspheres were facilely synthesized as model photocatalysts and characterized by XRD, SEM, TEM/HRTEM, XPS, nitrogen adsorption-desorption, UV-vis DRS, photoluminescence, and FTIR. The characterizations and photodegradation tests suggested that the composites had both adsorption sites and photocatalysis sites on BiOBr phase, while homogeneously distributed TiO2 in BiOBr microplates tailored the size of BiOBr crystallites. Accordingly, surface areas of the composites spanned from 22 to 155 m2/g and adsorption capacities for methyl orange (MO) ranged from 16 to 54 mg/g, controlled by the TiO2 content. In addition to experiments, kinetic modeling that combined adsorption with photocatalysis was developed and aided elucidating the synergy and quantitatively evaluating the composites with extracted rate constants from experimental data. The rate constant of the composite (Ti/Bi = 0.6) was calculated to be 3 times that of the pure BiOBr. Though adsorption promoted MO photodegradation, the capacity of the composite for MO adsorption and photodegradation decreased dramatically during the cycling tests. Nevertheless, this problem did not happen during photodegradation of rhodamine B and phenol on the composite and photodegradation of MO on pure BiOBr. This was explained by possible accumulation of degradation intermediates on the composite surface. This study provides a useful approach to investigate the adsorption-photocatalysis synergy from the perspectives of experiments and kinetic modeling and implies the necessity of scrutinizing the adverse effects of high levels of adsorption on recyclability of the photocatalysts.
关键词： Organic pollutants photodegradation,Kinetic modeling,TiO2-BiOBr microspheres,Tailorable adsorption capacities,Adsorption-photocatalysis synergy
更新于2025-11-14 17:03:37
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Power Efficiency Figure of Merit for Image Sensors
摘要： A new figure of merit (FoM) is developed with a theory, which enables the comparison of power efficiency of different image sensors based only on the pixel array size, frame rate, and total power consumption. The mathematical foundation of the FoM is provided, enabling the application of FoM to a generic image sensor supporting various read-out configurations. The model assumes a nonlinear relationship between the power consumption and operating frequency of building blocks, and the nonlinear factor is numerically derived based on the analytical modeling of image sensors. The FoM is applied to the studies from 1999 to 2018, which clarifies the trend of improvement as well as visualizes several breakthroughs in the development history.
关键词： modeling,CMOS image sensor (CIS),power efficiency,figure of merit (FoM),power consumption
更新于2025-09-23 15:23:52
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A reliable and efficient small-signal parameter extraction method for GaN HEMTs
摘要： In this paper, a reliable and efficient parameter extraction method for GaN high electron mobility transistor (HEMT) small‐signal models has been proposed. By utilizing parameter scanning method, the initial values of the extrinsic elements are first extracted from the cold pinch‐off and cold unbiased measurement conditions, respectively. An iterative optimization algorithm is employed then to optimize the extrinsic elements. This scanning and iteration combined algorithm based on a direct extraction method of extrinsic elements can reduce the impact of the approximation error, which makes the determined values of the small‐signal parameters more reliable. The extraction flow has been realized in a Matlab program for efficiency. A 16‐element small‐signal equivalent circuit model (SSECM) for GaN HEMTs has been employed, and the new parameter extraction method has been validated by comparing the simulated small‐signal S‐parameters with the measured data from 0.1 GHz to 40 GHz for two different device dimensions.
关键词： small‐signal modeling,parameter extraction,GaN high electron mobility transistor (HEMT)
更新于2025-09-23 15:23:52
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[IEEE 2018 26th European Signal Processing Conference (EUSIPCO) - Roma, Italy (2018.9.3-2018.9.7)] 2018 26th European Signal Processing Conference (EUSIPCO) - Spatio-Spectral Multichannel Reconstruction from few Low-Resolution Multispectral Data
摘要： This paper deals with the reconstruction of a 3-D spatio-spectral object observed by a multispectral imaging system, where the original object is blurred with a spectral-variant PSF (Point Spread Function) and integrated over few broad spectral bands. In order to tackle this ill-posed problem, we propose a linear forward model that accounts for direct (or auto) channels and between (or cross) channels degradation, by modeling the imaging system response and the spectral distribution of the object with a piecewise linear function. Reconstruction based on regularization method is proposed, by enforcing spatial and spectral smoothness of the object. We test our approach on simulated data of the Mid-InfraRed Instrument (MIRI) Imager of the James Webb Space Telescope (JWST). Results on simulated multispectral data show a significant improvement over the conventional multichannel method.
关键词： Deconvolution,Image reconstruction,Inverse problems,Multispectral restoration,System modeling
更新于2025-09-23 15:23:52
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Methodology for diagnosing crack patterns in masonry structures using photogrammetry and distinct element modeling
摘要： Understanding the causes of damages on existing structures can augment preservation, renovation, and rehabilitation efforts. The aim of this work is to outline a method for diagnosing the most probable causes of cracks on existing structures using a combination of photogrammetry and distinct element modeling (DEM). Five experimental, masonry walls were constructed and cracked; the state of the wall before and after cracking was recorded using photogrammetry. Using distinct element modeling, each test wall was subjected to a variety of loading conditions including the same load case which was used to crack the wall during experimental testing. The crack patterns in the simulations were compared to the experimental crack patterns using a combined qualitative and quantitative method. The simulation which most closely reflected the existing damage patterns was selected as the most probable cause of the damages. For each of the test walls, the real simulated load had the closest fractional distance to the existing damage patterns captured by photogrammetry. This method was then applied to diagnose possible causes of cracking on a foundation wall in the Baptistery of San Giovani in Florence, Italy.
关键词： Distinct element modeling,Masonry,Building pathology,Diagnosis,Crack propagation,Photogrammetry
更新于2025-09-23 15:23:52
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LESS: LargE-Scale remote sensing data and image simulation framework over heterogeneous 3D scenes
摘要： Three-dimensional (3D) radiative transfer modeling of the transport and interaction of radiation through earth surfaces is challenging due to the complexity of the landscapes as well as the intensive computational cost of 3D radiative transfer simulations. To reduce computation time, current models work with schematic landscapes or with small-scale realistic scenes. The computer graphics community provides the most accurate and efficient models (known as renderers) but they were not designed specifically for performing scientific radiative transfer simulations. In this study, we propose LESS, a new 3D radiative transfer modeling framework. LESS employs a weighted forward photon tracing method to simulate multispectral bidirectional reflectance factor (BRF) or flux-related data (e.g., downwelling radiation) and a backward path tracing method to generate sensor images (e.g., fisheye images) or large-scale (e.g. 1 km2) spectral images. The backward path tracing also has been extended to simulate thermal infrared radiation by using an on-the-fly computation of the sunlit and shaded scene components. This framework is achieved through the development of a user-friendly graphic user interface (GUI) and a set of tools to help construct the landscape and set parameters. The accuracy of LESS is evaluated with other models as well as field measurements in terms of directional BRFs and pixel-wise simulated image comparisons, which shows very good agreement. LESS has the potential in simulating datasets of realistically reconstructed landscapes. Such simulated datasets can be used as benchmarks for various applications in remote sensing, forestry investigation and photogrammetry.
关键词： Landscape modeling,Image simulation,Radiative transfer
更新于2025-09-23 15:23:52
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Imitational modeling of synchronous measuring detector with increased noise immunity and precision
摘要： In this paper, an example of application, simulation results, noise and precision properties of a synchronous measuring detector with increased noise immunity and precision (not less than 1%) for the operation providing of primary sensors – thermal sensors and bridge sensors, in particular Hall sensors for magnetic field measurements are considered. As a result of the research, it was discovered that increasing the sensitivity of magnetometers based on Hall sensors leads to the allocation of the initial useful signal of the ultra-low level against the background of noise comparable with it. To allocate the output signal of the Hall sensor or thermal sensor in the background of noise, it is proposed to feed it with harmonic current with the further allocation of the information signal using a in-phase detector with a narrowband low-pass filter.
关键词： sensor,detector,precision,noise immunity,modeling
更新于2025-09-23 15:23:52
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[IEEE 2018 2nd International Conference on Data Science and Business Analytics (ICDSBA) - Changsha, China (2018.9.21-2018.9.23)] 2018 2nd International Conference on Data Science and Business Analytics (ICDSBA) - Tracking Comparison of P&O and INC Based MPPTs under Varying Weather Conditions
摘要： The paper discusses the application of data science and business analytics in the context of optoelectronics, focusing on modeling and simulation techniques for photovoltaic systems. It presents a novel approach to improving efficiency and performance through advanced data analysis methods.
关键词： data science,business analytics,optoelectronics,photovoltaic systems,simulation,modeling
更新于2025-09-23 15:23:52