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- 实验方案
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Modeling apparent camouflage-pattern color using segment-weighted spectra
摘要： Camouflage patterns for military applications, typically upon base materials such as dyed fabrics, consist of highly detailed camouflage patternings that are characterized by combined refectance spectra. The complexity of these camouflage patterns establishes a need for modeling camouflage-pattern reflectance for pattern evaluation as a function of distance. A metric for pattern evaluation is the apparent-camouflage-pattern reflectance spectrum, which is the total reflectance due to all contributions from component segments, within a wavelength range of interest, for light reflected from sufficiently large fabric samples ( ≥ 1m2), as a function of stand-off distance. This follows in that camouflage patterns tend to lose contributions to the total reflectance from component segments, having less coverage, with increasing standoff distance. Eventually, with increasing distance, reflectance of pattern segments having more coverage combine to produce the “apparent spectrum” of the camouflage pattern at far field. The physical characteristics of camouflage-pattern reflectance spectra are based on far-field and diffuse scattering properties of electromagnetic waves. Accordingly, a modeling approach can be developed to simulate camouflage-pattern spectra using diffuse-reflectance theory, which is based on decomposition of camouflage-pattern reflectance with respect to component segments of camouflage patterns. This paper presents a modeling approach and prototype simulations of camouflage-pattern reflectance within the visible range of wavelengths, which are relevant for evaluating camouflage fabrics with respect to realistic field conditions. A significant aspect of this modeling approach is that it can be extended for simulation of a wide range of factors influencing detection of camouflaged targets.
关键词： apparent color,di?use re?ectance,Camou?age patterns,camou?age modeling
更新于2025-09-23 15:23:52
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High quality factor cold sintered Li2MoO4BaFe12O19 composites for microwave applications
摘要： Ceramics-ceramic composites (1-x)Li2MoO4-xBaFe12O19 (LMO-BF12, 0.00≤x≤0.15) have been cold sintered at 120oC and their structure and properties characterized. X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that compositions were dual phase and had a dense microstructure. Composites in the xBF12-(1-x)LMO (0.0≤x≤0.15) series resonated at MW frequencies (~6GHz) with 5.6≤e r≤5.8 and Qf =16,000-22,000 GHz, despite the black colour of compositions with x > 0. The permeability of the composites was measured in the X band (~8 GHz) and showed an increase from 0.94 (x=0.05) to 1.02 (x=0.15). Finite element modelling revealed that the volume fraction of BF12 dictates the conductivity of the material, with a percolation threshold at 10 vol.% BF12 but changes in e r as a function of x were readily explained using a series mixing model. In summary, these composites are considered suitable for the fabrication of dual mode or enhanced bandwidth microstrip patch antennas.
关键词： Finite element modeling (FEM),Composite,Cold sintering process,Dielectric,Ceramic material
更新于2025-09-23 15:23:52
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New modeling method for UV sensor photoelectrical parameters extraction
摘要： In this work, we have developed a new modeling tools based on physical, mathematical and numerical models for the analysis of UV-photodetectors based on ZnO NRs/PPV-C6 hybrid heterojunctions. The photoelectrical equivalent circuit parameters are the series resistance (Rs), the shunt resistance (Rp), the reverse current density (J0), the ideality factor (n) and the photocurrent density (Jph). A combined physical-mathematical-numerical approach based on the modified Schockley model, the Lambert W function and the optimized method of the Root Mean Square error (RMSE) was applied to analyze the different devices performances. The results demonstrate that the incorporation of PPV-C6 polymer to the ZnO NRs structure leads to significant amelioration in the interface and increase of both the Jph and responsivity with a decrease of the Rs. This kind of hybrid heterojunction based UV light sensor is promising for future low cost and high performance optoelectronic devices development.
关键词： Photodetectors,Hybrid heterojunction,UV sensor,Modeling,Photoelectrical properties
更新于2025-09-23 15:23:52
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Distributed Small-signal Equivalent Circuit Model and Parameter Extraction for SiGe HBT
摘要： In this paper, we present an improved high frequency small-signal distributed model for SiGe HBTs under forward-active mode based on the transmission line theory. The distributed nature of the transistor structure is taken into account in the proposed model. The single SiGe HBT is considered to be a cascade of many infinitesimal transistors, connected with the intrinsic base resistance. The closed-form solutions of admittance parameters for the distributed model are derived by solving the transmission line equation. With reasonable approximation and simplification, the model parameters are then directly extracted based on the nonlinear rational function fitting. The new improved distributed model and parameter extraction technique are validated with a 1×1.2×30 μm2 SiGe HBT from 100 MHz to 20.89 GHz. The simulated S-parameters in the proposed transmission line model are in close agreement with the measured data, and the frequency characteristics of the transistors are well predicted.
关键词： parameter extraction,rational function fitting,transmission line,SiGe HBT,Device modeling,small-signal model
更新于2025-09-23 15:23:52
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[IEEE 2017 5th International Conference on Mechanical, Automotive and Materials Engineering (CMAME) - Guangzhou (2017.8.1-2017.8.3)] 2017 5th International Conference on Mechanical, Automotive and Materials Engineering (CMAME) - Modeling and Application of Output Current of the Solar Array for Satellite in Sun Synchronous Orbit
摘要： The output current of the solar array for satellite in sun synchronous orbit is a critical parameter for performance in-orbit analyzing. In order to analysis the rules of the solar array output current accurately, some influential factors, such as the incidence angle of the sun, the temperature of the solar array, the earth-sun distance factor and the fixed offset angle to the sun of solar wing, are comprehensively researched. Then a model of output current is established. Results in-orbit show that the model has high accuracy, which can provide a reference for optimization design of satellite solar array.
关键词： the solar array,modeling,output current,sun synchronous orbit,satellite
更新于2025-09-23 15:23:52
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[IEEE 2018 26th International Conference on Geoinformatics - Kunming (2018.6.28-2018.6.30)] 2018 26th International Conference on Geoinformatics - Multilevel Solar Potential Analysis of Building Based on Ubiquitous Point Clouds
摘要： Solar potential analysis is essential for Building Information Modeling (BIM) applications, like photovoltaic installation. The estimation of solar potential on rooftops has been widely discussed, whereas the study on fa?ade is still limited. Benefit from the development of various sensors, ubiquitous point clouds are now widely and easily captured by photogrammetry, laser scanning or other technologies, to represent the building geometry. This paper proposes a method for solar potential analysis on both rooftops and fa?ades, using ubiquitous point cloud collected by Unmanned Aerial Vehicle (UAV) and Terrestrial Laser Scanning (TLS). One building with different orientations is selected for the case study. Results show that the proposed method is valid for multilevel solar potential analysis of buildings.
关键词： laser scanning,solar potential,ubiquitous point cloud,Building Information Modeling (BIM)
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Modeling and Verification of Ku-Band Tracking Radar System
摘要： Taking a certain type of Ku-band fire-control radar tracking system as example, the monopulse tracking radar standard library and simulation system are investigated and developed based on Simulink. Under the condition of true input value of flying target, the effectiveness and reliability of signal generator, clutter, Moving Target Indication (MTI), Moving Target Detection (MTD) and tracking module are verified. The actual measured data and simulation data are compared, the error is less than 1.5%. The operational frequency of the radar is 15 GHz and the bandwidth is 2 GHz.
关键词： system modeling,Simulink,Ku-band Radar
更新于2025-09-23 15:22:29
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Terahertz Differential Computed Tomography: a Relevant Nondestructive Inspection Application
摘要： In recent years, tremendous advances have been made in the choice of materials used in the industry. With weight reduction as the goal, composite and polymer materials are more and more popular but they are almost transparent to X-ray. Because of this, interest has grown in other wavelengths like terahertz (THz). Due to a difference in how X-ray and THz propagate, X-ray CT algorithms cannot be directly used. For example, THz induces refraction making the reconstruction problem nonlinear. In this paper, we present a new algorithm which complies with beam profile intensities, refraction, and reflection. It is based on linearizing the reconstruction process around a computer-aided design (CAD) model of the object to be reconstructed. The method we propose computes the deviation between the object and this model.
关键词： Terahertz computed tomography,Inverse problem,Nondestructive testing,Modeling,Monte Carlo,Refraction,Nonlinear problem,Projection simulation
更新于2025-09-23 15:22:29
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Mathematical modeling on non-dispersive extraction of germanium from aqueous solutions using Aliquat 336
摘要： In this work, the mathematical modeling of the facilitated transport of germanium (non-dispersive extraction) through a flat sheet membrane with an Aliquat 336 carrier was described. The flat sheet supported liquid membrane (FSSLM) experiments were performed under the condition being Ge ≈ 100 mg/L, the tartaric acid concentration of 2.76 mmol/L, and carrier concentrations of 2.5 to 10%v/v. The extraction equilibrium, mass transfer and diffusion equations based on Fick’s law were used. Modeling was carried out by programming in Matlab mathematical software to obtain the extraction (Kex) and mass transfer constants (Km) as the objective parameters. According to the model resolution, Kex and Km were found to be 0.178 and 9.25 × 10?2 cm/s, respectively. The correlation coefficients between model and experimental data relating to the Aliquat 336 concentrations of 2.5, 5, 7.5, and 10%v/v were found as 0.96, 0.98, 0.99, and 0.92. The parameters of root mean square (RMSE), bias, and scatter index (SI) showed the model accuracy. In addition, diffusion coefficients (Dm) relating to Aliquat 336 concentrations of 2.5, 5, 7.5, and 10%v/v were calculated using mass transfer coefficients to be 2.4 × 10??, 2.23 × 10??, 1.91 × 10??, and 1.79 × 10?? cm2/s, respectively.
关键词： supported liquid membrane,Aliquat 336,modeling,germanium,mass transfer
更新于2025-09-23 15:22:29
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Phonon-assisted tunneling in direct-bandgap semiconductors
摘要： In tunnel ?eld-effect transistors, trap-assisted tunneling (TAT) is one of the probable causes for degraded subthreshold swing. The accurate quantum-mechanical (QM) assessment of TAT currents also requires a QM treatment of phonon-assisted tunneling (PAT) currents. Therefore, we present a multi-band PAT current formalism within the framework of the quantum transmitting boundary method. An envelope function approximation is used to construct the electron-phonon coupling terms corresponding to local Fr?hlich-based phonon-assisted inter-band tunneling in direct-bandgap III-V semiconductors. The PAT current density is studied in up to 100 nm long and 20 nm wide p-n diodes with the 2- and 15-band material description of our formalism. We observe an inef?cient electron-phonon coupling across the tunneling junction. We further demonstrate the dependence of PAT currents on the device length, for our non-self-consistent formalism which neglects changes in the electron distribution function caused by the electron-phonon coupling. Finally, we discuss the differences in doping dependence between direct band-to-band tunneling and PAT current.
关键词： phonon-assisted tunneling,quantum-mechanical modeling,tunnel ?eld-effect transistors,electron-phonon coupling,direct-bandgap semiconductors
更新于2025-09-23 15:22:29