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- 摘要
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Uncertainty of Phasor Measurement Unit Calculated by Means of Monte Carlo Method
摘要： Whole measurement chain of a Phasor Measurement Unit was simulated and uncertainty of Total Vector Error (TVE) has been calculated using Monte Carlo Method. The results showed the most important uncertainty contributions and behaviour of the probability distribution function of the output uncertainty. Asymmetrical uncertainties of TVE have to be calculated to obtain proper values.
关键词： simulation,total vector error,measurement uncertainty,phasor measurement unit,monte carlo
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Calculation of Voltage Reflection Coefficients of Coaxial Airlines and Evaluation of Their Measurement Uncertainties at SCL
摘要： This paper describes the use of a simple software tool developed by Standards and Calibration Laboratory (SCL) to calculate the voltage reflection coefficients (VRC) of coaxial airlines and evaluate their measurement uncertainties with Monte Carlo method. The results can be used to verify vector network analyzer before using it to take measurement.
关键词： Coaxial airlines,measurement uncertainties,voltage reflection coefficients,Monte Carlo method
更新于2025-09-10 09:29:36
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The metal-free magnetism and ferromagnetic narrow gap semiconductor properties in graphene-like carbon nitride
摘要： In spintronics, if a two-dimensional (2D) organic metal-free material has stable magnetism and narrow gap semiconductor properties, it will have a very bright application prospect. A graphene-like carbon nitride (g-C13N13) that we design just meets these requirements. As a new structure, firstly the stability of the g-C13N13 has been verified. It has stable electron spin polarization and the magnetic moment of each primitive cell is 1μB. It exhibits ferromagnetic narrow gap semiconductor properties through our analysis of energy band structure and charge density. Ferromagnetic ordering between two adjacent primitive cells is stable. The Monte Carlo simulation using the Ising model shows the Curie temperature material is 204K. Our research is an inspiration for the applications of this kind of materials in spintronics devices.
关键词： Metal-free magnetism,Electron spin polarization,Ferromagnetic ordering,Narrow gap semiconductor properties,Monte Carlo simulations
更新于2025-09-10 09:29:36
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Phase-field method for epitaxial kinetics on surfaces
摘要： We present a procedure for simulating epitaxial growth based on the phase-field method. We consider a basic model in which growth is initiated by a flux of atoms onto a heated surface. The deposited atoms diffuse in the presence of this flux and eventually collide to form islands which grow and decay by the attachment and detachment of migrating atoms at their edges. Our implementation of the phase-field method for this model includes uniform deposition, isotropic surface diffusion, and stochastic nucleation (in both space and time), which creates islands whose boundaries evolve as the surface atoms "condense" into and "evaporate" from the islands. Computations using this model in the submonolayer regime, prior to any appreciable coalescence of islands, agree with the results of kinetic Monte Carlo (KMC) simulations for the coverage-dependence of adatom and island densities and island-size distributions, for both reversible and irreversible growth. The scaling of the island density, as obtained from homogeneous rate equations, agrees with KMC simulations for irreversible growth and for reversible growth for varying deposition flux at constant temperature. For reversible growth with varying temperature but constant flux, agreement relies on an estimate of the formation energy of the critical cluster. Taken together, our results provide a comprehensive analysis of the phase-field method in the submonolayer regime of epitaxial growth, including the verification of the main scaling laws for adatoms and island densities and the scaling functions for island-size distributions, and point to the areas where the method can be extended and improved.
关键词： epitaxial growth,reversible and irreversible growth,kinetic Monte Carlo simulations,island-size distributions,phase-field method
更新于2025-09-10 09:29:36
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Light propagation in biological tissue
摘要： We developed a new parallel computational method for solving fluorescence and elastically scattered light propagation through a biological tissue illuminated by a collimated incident beam. The three-dimensional steady state radiative transfer equation was solved using a Modified Finite Volume Method with a cell-vertex formulation. An Exponential spatial differencing scheme was used to efficiently lessen the false scattering. Several test problems are presented to assess the performance and accuracy of the numerical Method. We show that it is possible to obtain a very good level of accuracy. Relative differences less than 1.5% were obtained in comparison with the Monte Carlo reference solution for the selected problems. This study shows the potential of the proposed computational method to be used as an accurate deterministic forward solver in Optical Tomography.
关键词： Monte carlo method,Parallel computing,Finite volume method,Fluorescence light,Elastically scattered light,Radiative transfer equation,Biological tissue
更新于2025-09-10 09:29:36
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Performance evaluation of total variation (TV) denoising technique for dual-energy contrast-enhanced digital mammography (CEDM) with photon counting detector (PCD): Monte Carlo simulation study
摘要： The dual-energy contrast-enhanced digital mammography (CEDM) system based on a photon counting detector (PCD) is very useful providing functional information for breast cancer detection. In particular, this system can be used to solve the spectral overlap and high radiation dose problems. However, imaging noise is a big problem because of the degradation image performance and cancer detection ratio in the CEDM system. To address this problem, a total variation (TV)-based denoising technique approach has recently been studied. Thus, the aim of this study was to evaluate and confirm the image performance of our TV-based denoising technique with dual-energy CEDM with a PCD. For this purpose, we simulated a dual-energy CEDM with a PCD and breast phantom in Monte Carlo simulation using the Geant4 Application for Tomographic Emission (GATE) that is an essential open source program. We also designed a TV-based denoising technique based on the L1-norm estimation included correction and iteration steps for acquiring high edge preservation in X-ray images. To evaluate the image performance, we used evaluation parameters with a contrast-to-noise ratio (CNR) and coefficient of variation (COV) as a function of the absorbed dose levels (2.18, 1.53, 1.09, and 0.66 mGy). According to the results, the average of all iodine thicknesses and absorbed dose conditions for the CNR using our proposed TV-based denoising technique was 1.71, 1.39, and 1.13 times higher than that acquired for the noisy image, median filter and Wiener filter, respectively. We also acquired excellent COV results for the dual-energy CEDM with a PCD system (2.53 times higher than that of the noisy image). In conclusion, the results of this study suggested that a TV-based denoising technique can be achieved with an improved image performance and the effect and feasibility of the TV-based denoising technique for dual-energy CEDM with a PCD can be investigated.
关键词： Dual-energy imaging method,Monte Carlo simulation,Total variation (TV)-based denoising technique,Photon counting detector (PCD),Evaluation of image performance,Contrast-enhanced digital mammography (CEDM)
更新于2025-09-10 09:29:36
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[IEEE 2018 Iranian Conference on Electrical Engineering (ICEE) - Mashhad (2018.5.8-2018.5.10)] Electrical Engineering (ICEE), Iranian Conference on - Analytical Approaches for Determining Optimal Tilt Angle and Orientation of PV Modules Considering Regional Climate Conditions
摘要： The increasing growth of solar power plants installation necessitates performing accurate investigations on new methods to find optimum tilt angel and orientation of photovoltaic (PV) panels. Using optimum methods increases collected solar irradiance, and consequently, maximize the expected annual harvested energy, which means better financial performance of PV power plants. In this paper, the optimum tilt angle and orientation of PV panels are calculated by introducing two accurate analytic methods, which take into account the climate conditions of the installation region by considering wind speed, irradiance and ambient temperature. The results of this paper, which are supported by Monte Carlo simulation, indicate that compared with the traditional method, an increase in expected annual produced energy of solar panels is achievable using the optimum tilt angel and orientation calculated by the presented methods.
关键词： photovoltaic,orientation,analytical method,Monte Carlo,tilt angle
更新于2025-09-10 09:29:36
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Molecular Mechanics Simulations and Improved Tight-Binding Hamiltonians for Artificial Light Harvesting Systems: Predicting Geometric Distributions, Disorder, and Spectroscopy of Chromophores in a Protein Environment
摘要： We present molecular mechanics and spectroscopic calculations on prototype artificial light harvesting systems consisting of chromophores attached to a tobacco mosaic virus (TMV) protein scaffold. These systems have been synthesized and characterized spectroscopically, but information about the microscopic configurations and geometry of these TMV-templated chromophore assemblies is largely unknown. We use a Monte Carlo conformational search algorithm to determine the preferred positions and orientations of two chromophores, Coumarin 343 together with its linker, and Oregon Green 488, when these are attached at two different sites (104 and 123) on the TMV protein. The resulting geometric information shows that the extent of disorder and aggregation properties, and therefore the optical properties of the TMV-templated chromophore assembly, are highly dependent on the choice of chromophores and protein site to which they are bound. We used the results of the conformational search as geometric parameters together with an improved tight-binding Hamiltonian to simulate the linear absorption spectra and compare with experimental spectral measurements. The ideal dipole approximation to the Hamiltonian is not valid since the distance between chromophores can be very small. We found that using the geometries from the conformational search is necessary to reproduce the features of the experimental spectral peaks.
关键词： tobacco mosaic virus (TMV),linear absorption spectra,spectroscopic calculations,artificial light harvesting systems,Monte Carlo conformational search,tight-binding Hamiltonian,molecular mechanics,chromophores
更新于2025-09-10 09:29:36
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Object-based correction of LiDAR DEMs using RTK-GPS data and machine learning modeling in the coastal Everglades
摘要： Light Detection and Ranging (LiDAR) Digital Elevation Models (DEMs) are frequently applied in modeling coastal environments. We present an object-based correction approach for accurate and precise DEMs by integrating LiDAR point data, aerial imagery, and Real Time Kinematic-Global Positioning Systems. Four machine learning techniques (Random Forest, Support Vector Machine, k-Nearest Neighbor, and Artificial Neural Network) were compared with the commonly used bias-correction method. The Random Forest object-based model produced best predictions for two study areas: Nine Mile (Mean Bias Error (MBE) reduced 0.18 to ?0.02 m, Root Mean Square Error (RMSE) reduced 0.22 to 0.08 m) and Flamingo (MBE reduced 0.17 to 0.02 m, RMSE reduced 0.24 to 0.10 m). A Monte Carlo model was developed to combine errors into the object-based machine learning corrected DEMs, and uncertainty maps spatially revealed the likelihood of error. The object-based correction approach provides an attractive alternative to the bias-correction method.
关键词： DEMs,Object-based image analysis,Monte Carlo,LiDAR,Machine learning,Coastal wetlands
更新于2025-09-10 09:29:36
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Variance Analysis in 3-D Integration: A Statistically Unified Model With Distance Correlations
摘要： Variability is a challenge for future scaling as process dimensions reduce. The emerging 3-D sequential stacking technology is more than Moore’s scaling alternative. The 3-D design ?ow requires the partitioning of the netlist between the tiers. This paper presents the variability analysis of circuits partitioned into different levels. A comparison among local and global variations effects on ring oscillators (ROs) and SRAM is demonstrated. The across-chip variations and correlation range are shown as a critical point for the 3-D very large-scale integrated circuits, where the local variability is dominant. The correlations between devices due to the distances or the allocation into different tiers are directly taken into account in the SPICE model due to a statically uni?ed model applied to 3-D circuits based on Monte Carlo simulations. Design wise, the 3-D integration can further decrease the circuit variability as shown in RO output frequency and SRAM static noise margin.
关键词： across-chip variations (ACVs),variability,3-D very large-scale integration (VLSI),SRAM,noise margins,Monte Carlo (MC),3-D integration
更新于2025-09-10 09:29:36