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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Performance Analysis of Speckle Filtering on Single-Look Polsar Data for Land Cover Classification
摘要： The speckle ?ltering is an essential preprocessing step of polarimetric SAR (PolSAR) data processing. The PolSAR speckle ?lters perform generally better on multilook datasets. The multilooking is performed to reduce speckle and improve parameter estimation but it also degrades resolution of the datasets. The speckle ?ltering after multilooking further degrades the resolution. The analysis on suitability of speckle ?ltering algorithms for single-look data is absent in the literature. In this paper, state-of-the-art PolSAR speckle ?lters are analyzed for the single-look PolSAR data. The single-look Monte Carlo simulated and real RADARSAT-2 PolSAR data are used for performance analysis.
关键词： SAR,polarimetric,Monte Carlo simulation,?ltering,Speckle
更新于2025-09-10 09:29:36
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Numerical Study of a Hybrid Optical DMT/DFT-S QAM Modulation
摘要： A hybrid modulation offers the peak-to-average power ratio (PAPR) robustness of discrete Fourier transform spread (DFT-S) QAM (quadrature amplitude modulation) with the bit rate optimization of discrete multi-tone (DMT) modulation. We examine via simulation under what circumstances this hybrid can increase achievable bit rate. Hybrid PAPR reduction allows us to increase the peak-to-peak voltage at the modulator electrical input to increase the signal mean power at the modulator output. We propose a methodology to identify the optimal driving strategy. We optimize the bit rate for the available spectrum, i.e., the spectral efficiency, taking into account the bandwidth limited nature of the transmitter. The final optimization we propose is the partition of the available spectrum into a lower frequency band for DFT-S QAM and a higher frequency band for DMT. The modulation level of the DFT-S QAM is also optimized. We compare the optimal hybrid performance versus DMT performance for a range of bit rates for a given modulation bandwidth. Improved performance comes at the cost of greater DSP complexity for the hybrid solution. We compare the number of complex multipliers required to implement hybrid versus DMT for both dispersive and non-dispersive systems.
关键词： simulation,DFT-spread,QAM,complexity comparison,frequency optimization,DMT,hybrid
更新于2025-09-10 09:29:36
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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Evaluation of Lighting Design Based on Computer Simulation
摘要： Photorealistic computer simulations are now a popular method of lighting design. They are usually associated with the illumination of objects, but they are also successfully used in interior lighting, especially representative lighting. The problem of the verifiability of the tool is often discussed and in which cases only visualization without purely analytical calculations can be used to evaluate the lighting design. The article presents both subjective and objective studies of conformity of a project made using photorealistic visualization and its subsequent implementation. Subjectively it means based on the comparison of simulation images made with different accuracy, with post-implementation photographs of these projects, objectively – on the basis of measurements of the luminance of the completed project and their reference to distributions previously generated by computer. The field measurements carried out as well as surveys have clearly shown that computer simulations in the form of raster images are a reliable design tool in the hands of a lighting designer. The future of the lighting design is also presented.
关键词： advanced lighting simulation,lighting design,virtual reality of lighting,floodlighting
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - The Simulation of Ocean Surface Wind Measured by Polarimetric Scatterometer
摘要： Ocean surface wind field is a very important marine dynamic parameter in marine environment forecasting and climatological studies. Spaceborne scatterometer is one of the most efficient remote sensors than can provide global ocean surface wind measurement. Polarimetric scatterometer (PolScat) simultaneously measures co-polarized and cross-polarized backscattering coefficient and the correlation coefficient of the co- and cross-polarized component of radar echoes which can significantly improve the performance of the sea surface wind field measurements. In this paper, we derive the error model of correlation scattering coefficient from radar echo signals. The effect of antenna polaxis deflection on correlation scattering coefficient error is analyzed. Moreover, an “end-to-end” system simulation model of PolScat is established. A modified Maximum Likelihood Estimation (MLE) is used for ocean surface wind field inversion. Both the co-polarized backscattering coefficient and correlation scattering coefficient are included in the objective function of MLE. The simulation results show that PolScat can effectively reduce the probability of ambiguous solutions. The wind speed and wind direction inversion accuracy of PolScat is better than 1m/s and 15° respectively.
关键词： inversion accuracy,system simulation,ocean surface wind vector,Polarimetric scatterometer
更新于2025-09-10 09:29:36
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A review on modeling and simulation of solar energy storage systems based on phase change materials
摘要： Phase Change Materials (PCM) have been widely used in different applications. PCM is recognized as one of the most promising materials to store solar thermal energy in the form of latent heat. Utilization of PCMs for solar energy storage compensates for the intermittent characteristic of this energy source. Mathematical modeling and numerical simulation of solar energy storage systems provide useful information for researchers to design and perform experiments with a considerable saving in time and investment. This paper is focused on modeling and simulation of PCM based systems that are used in different solar energy storage applications. A thorough literature review is performed to investigate and compare the results and accuracy of different mathematical models, numerical methods and thermodynamic analysis of using different PCMs in different solar systems. Moreover, the potential research areas in numerical simulations and thermodynamic analysis of solar systems based on PCMs are determined considering the existing gaps in the literature.
关键词： Phase change materials,Solar energy storage systems,Numerical modeling,Simulation
更新于2025-09-10 09:29:36
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Terahertz Time Domain Spectroscopy of Transformer Insulation Paper after Thermal Aging Intervals
摘要： An accelerated thermal aging process was used to simulate the condition of paper insulation in transformer oil-paper systems. Optical parameters of the insulation paper after various aging intervals were analyzed with terahertz time-domain spectroscopy (THz-TDS) over the range 0.1~ 1.8 THz. The result shows that the paper had seven absorption peaks at 0.19, 0.49, 0.82, 1.19, 1.43, 1.53, and 1.74 THz, and density functional theory of B3LYP/6-311G+ (d, p) was used to simulate the molecular dynamics of the repeating component (cellobiose) of the cellulose paper. Theoretical spectra were consistent with experiment, which had absorption peaks at 0.18, 0.82, 1.47, and 1.53 THz in the same frequency range. At the same time, the paper samples after various aging intervals had different refractive indexes, and least squares ?tting revealed a linear relationship between the degree of polymerization and the refractive index of the paper. Hence, this paper demonstrates that THz-TDS could be used to analyze the aging condition of transformer insulation paper and provides the theoretical and experimental basis for detection.
关键词： transformer insulation paper,novel diagnostic technique,molecular dynamics simulation,DFT,terahertz-time-domain spectroscopy
更新于2025-09-10 09:29:36
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The Modeling and Analysis of a Power Transmission Line Supplied by a Solar Power Plant
摘要： This article deals with the energy transmission line system which feeds from solar energy at the MATLAB Simulink. So, direct voltage is considered to be converted as an alternating voltage by a 35-level inverter after the solar power plant which has the power of 110 MW produce 360 kV of direct voltage. A line which covers 240 km of distance is preferred to transmit electrical power from the A1 point to an A2 point. Due to this, the required mathematical equations are calculated with a circuit analyzing method for the line modeling in the simulation. Experiments on the model are carried out at the MATLAB Simulink after the creation of an energy transmission line. After that, when measurements are made taking into consideration the A2 node; the capacitor voltage, the transformer current, the A2 node current, and the fault current, values are given according to the converted voltage at the frequencies of 100 Hz, 80 Hz, and 50 Hz. The obtained results demonstrate the success of the proposed line system, while power is distributed with eliminated fault at a long distance at different frequencies.
关键词： mathematical model of the line,simulation model of the transmission line,35-level inverter
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Reconstruction of 3D Forest Mock-Ups from Airborne LiDAR Data for Multispectral Image Simulation Using DART Model
摘要： Three dimensional(3D) radiative transfer simulation is becoming an important and essential tool to understand the interaction between solar radiation and forestcanopies. However, conducting a 3D simulation usually needsa lot of input parameters, especially the 3D informationof forest scene, which is difficult to obtain and reconstruct. This paper presents a voxel approach that derives forest mock-upsfrom LiDAR data. These 3D mock-ups are adapted to DART model, using its recently introduced data access objects (DAO) tool. Here, they are used to simulate multispectral imageswith DART.
关键词： image simulation,LiDAR,forest,3D reconstruction
更新于2025-09-10 09:29:36
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First-principles investigation on the interlayer doping of SnSe2 bilayer
摘要： Using density functional theory calculations, we systematically investigated the effects of numbers and types of transition metals (TM) on the magnetic property of SnSe2 bilayer nanosheet. Our results revealed that, when one TM is introduced into the interlayer, the magnetic moment induced by the Co and Ni is tiny while it is largely strengthened with the doping of V, Cr, Mn, and Fe. When two TMs are inserted into the interlayer, Vand Cr make the system change into a weak antiferromagnetism (AFM) state while Mn-, Fe-, Co-doped systems display a weak ferromagnetism (FM) ground state. These FM states have the magnetic moments which double those of the one TM–doping systems. With the TM numbers further increasing to four, the robust AFM and FM features appear with the doping of Fe and Mn, respectively. Ni cannot induce any magnetism whatever the numbers of Ni are filling in. Interestingly, with the increase of the numbers of dopants, transitions from FM to AFM and AFM to FM are predicted to be realized on Fe-SnSe2 and Cr-SnSe2 systems, respectively. This kind of transition may be important for the applications in spintronic devices.
关键词： Interlayer doping,Spintronics application,Density functional theory,Antiferromagnetism,Modeling and simulation,Ferromagnetism,SnSe2
更新于2025-09-10 09:29:36
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Analysis of the damage initiation in a SiC/SiC composite tube from a direct comparison between large-scale numerical simulation and synchrotron X-ray micro-computed tomography
摘要： Damage initiation is an important issue to understand the mechanical behavior of ceramic matrix composites. In the present work, a braided SiC/SiC composite tube was studied by FFT simulation tightly linked with micro-computed tomography (μCT) observations performed during an in situ uniaxial tensile test, which provide both the real microstructure, with a good description of local microstructural geometries, and location of cracks at the onset of damage. The FFT method was proven applicable to tubular structures and efficient to complete the large-scale simulation on a full resolution μCT scan (~6.7 billion voxels) within a short time. The edge effect due to the numerical periodic boundary conditions prescribed on the real and not rigorously periodic microstructure was quantified. The obtained stress field was compared to the cracks detected by the in situ μCT observations of the same composite tube. This one-to-one comparison showed that cracks preferentially initiated at tow interfaces, where sharp edges of macropores are mostly located and generate stress concentrations.
关键词： Damage initiation,FFT simulation,Ceramic matrix composite,In situ tensile test,Tomography,Porosity effect
更新于2025-09-10 09:29:36