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An improved scheme and numerical simulation of segmented planar imaging detector for electro-optical reconnaissance
摘要： Segmented planar photoelectric detection imaging technology is a cutting-edge photoelectric imaging technology developed to realize the miniaturization and weight reduction of imaging systems. The imaging process of the integrated optical interferometry system was simulated by a computer simulation algorithm, and the influence of the system’s structural parameters on the imaging results was explored. Moreover, an optimal scheme of the baseline matching method was proposed. The simulation results showed that increasing the number of interferometer arms and baselines can improve the imaging quality of the system. The proposed baseline matching optimization method could improve the low-frequency sampling rate of the system and thus, improve the imaging quality. In addition, simulation results also gave the optimal imaging distance of the system, which indicates that the system is most suitable for remote sensing imaging, meanwhile measuring the system’s tolerance limit to phase noise. The requirements for the precision of waveguide fabrication are given, which play a guiding role in system manufacturing.
关键词： Photoelectric detection,Numerical simulation,Photonic integrated circuit,Baseline optimization scheme,Interference imaging
更新于2025-09-12 10:27:22
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Methods of extraction of optical properties from diffuse reflectance measurements of ex-vivo human colon tissue using thin film silicon photodetector arrays
摘要： Spatially resolved di?use re?ectance spectroscopy (SRDRS) is a promising technique for characterization of colon tissue. Herein, two methods for extracting the reduced scattering and absorption coe?cients (μ(cid:48) s(λ) and μa(λ)) from SRDRS data using lookup tables of simulated di?use re?ectance are reported. Experimental measurements of liquid tissue phantoms performed with a custom multi-pixel silicon SRDRS sensor spanning the 450 - 750 nm wavelength range were used to evaluate the extraction methods, demonstrating that the combined use of spatial and spectral data reduces extraction error compared to use of spectral data alone. Additionally, SRDRS measurements of normal and tumor ex-vivo human colon tissue are presented along with μ(cid:48) s(λ) and μa(λ) extracted from these measurements.
关键词： optical properties,Spatially resolved di?use re?ectance spectroscopy,colon tissue,Monte Carlo simulation,lookup tables
更新于2025-09-12 10:27:22
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[IEEE 2019 International Conference on Applied Electronics (AE) - Pilsen, Czech Republic (2019.9.10-2019.9.11)] 2019 International Conference on Applied Electronics (AE) - Electromagnetic Interference from DC/DC Converter of Photovoltaic System
摘要： This paper is focused on electromagnetic interference from DC/DC converter of photovoltaic system for home application. This converter produces disturbances in a wide frequency range. According to international standard CISPR 11, the frequency range for disturbance measurement could be divided to two sub-ranges (150 kHz – 30 MHz and above 30 MHz). All parts of the DC/DC converter is non-ideal and its have a parasitic parameters (especially passive components like an inductor and capacitor). These parasites often show unpredictable interference that is not easy to suppress. The simulation results of a buck converter are presented in the paper and the question about measurement correctness of the radiated emission of this device type according to the relevant standard is asked.
关键词： LISN,EMC,photovoltaic,conducted emission,GCPS,radiated emission,CISPR 11,simulation,converter,AMN
更新于2025-09-12 10:27:22
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Numerical analysis of process dynamics in laser welding of Al and Cu
摘要： The process windows for welding Al and Cu are quite limited due to process instabilities like spiking or humping that lead to severe welding failures. Within this paper the fluiddynamical reasons for these instabilities will be analysed by means of multiphysical numerical simulations of the laser beam welding process. After a short introduction into the process model, the simulation results will be verified on basis of experimental results. Then we will focus on the analysis of the different process dynamics during welding for both Al and Cu. The reasons for the humping and spiking instabilities will be revealed. Finally an outlook on current developments, e.g. concerning the grain growth during solidification, will be given.
关键词： spiking,laser welding,welding defects,multiphysical simulation,humping
更新于2025-09-12 10:27:22
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Stress distribution in laser metal deposited multi-layer thick-walled parts of Ti-6Al-4V
摘要： The laser metal deposition is an additive manufacturing technology enabling the production of large scale complex parts without additional treatment like welding or machining. The study of the origin of the stress field during laser metal deposition is essential for solving a number of problems, including: the assessment of cold and hot cracking; prediction of the fatigue resistance, and the stress corrosion cracking. The quantitative study of transient and residual stresses in build parts is necessary for optimising the parameters of processing and post-production stress relieving heat treatment. Residual stress field in laser metal deposited 50-layer (4-pass per layer) wall of Ti-6Al-4V was analysed experimentally using neutron diffraction and numerically using finite element simulation. Long dwell time between passes and a rigid substrate was used in order to simulate conditions of large scale parts fabrication. An analysis of the calculated and experimentally measured residual stress field showed that near the edges of the buildup there is a region where all three components of stress field are tensile, and normal stress exceeds the yield stress by more than 25%. Moreover, normal plastic strain in this area are also tensile and reaches 2.5-3%. The longitudinal tensile stress closes to yield stress on almost the entire length of the several last layers near the top of the buildup. Residual stress field calculated using neutron diffraction data according to interplanar lattice distance obtained assuming plane stress approach has a satisfactory agreement with FE simulated results.
关键词： Neutron diffraction,Laser metal deposition,Simulation,Residual stress,Titanium alloy
更新于2025-09-12 10:27:22
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[IEEE 2019 23rd International Conference on Mechatronics Technology (ICMT) - SALERNO, Italy (2019.10.23-2019.10.26)] 2019 23rd International Conference on Mechatronics Technology (ICMT) - Analysis of Fuel Savings Enabled by Photovoltaic Panel Addition on a 48V Mild Hybrid Vehicle
摘要： Recovering solar energy, and then fully reusing it, can significantly improve light duty vehicles’ efficiency, hence reducing the CO2 emissions and fuel consumption. The aim of this study is to investigate and explain how the solar energy flow affects the fuel economy (FE) and CO2 benefit in a particular hybrid vehicle configuration. The paper starts with the explanation of two different simulation models of a conventional vehicle and a mild hybrid (MH) vehicle along a defined path. A method is defined to estimate the battery state of charge constraint relaxing and then a modified forward model is used to assess solar energy contribution. An analysis of the three models (conventional, MH and solar mild hybrid) along a federal urban driving schedule (FUDS) is presented to compare the correct behavior of the models to follow a defined path and the improvements in terms of FE and CO2 emissions obtained via solar hybridization.
关键词： control,mild hybridization,solar cars,design,simulation,hybrid vehicles
更新于2025-09-12 10:27:22
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Toward Highly Thermal Stable Perovskite Solar Cells by Rational Design of Interfacial Layer
摘要： Heat is crucial to the long term stability of perovskite solar cells (PVSCs). Herein, thermal stability of PVSCs based on metal oxide (MO) and polymer (P) was investigated. Firstly, chemical decomposition behavior of perovskite films was characterized and analyzed, revealing that chemically active MO would accelerate the decomposition of methylamine lead iodide (MAPbI3). Secondly, thermal-induced stress, resulting from the mismatched thermal expansion coefficients of different layers of PVSCs, and its effect on the mechanical stability of perovskite films were studied. Combining experiment and simulation, we conclude that “soft” (low modulus) and thick (> 20 nm) interfacial layers offer better relaxation of thermal-induced stress. As a result, PVSCs employing thick polymer interfacial layer offer a remarkably improved thermal stability. This work offers not only the degradation insight of perovskite films on different substrates, but also the path toward highly thermal stable PVSCs by rational design of interfacial layers.
关键词： perovskite solar cells,mechanics simulation,interfacial layer,heat endurance,kinetics analysis
更新于2025-09-12 10:27:22
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Luminescent properties of CaSc2O4:Ce3+ green phosphor for white LED and its optical simulation
摘要： Green-emissive Ce3t-doped CaSc2O4 phosphors were synthesized by solid-state method. The water washing process of the as-prepared samples was several times conducted because of severe hydration of unreacted CaO and CaF2 flux residual. The washed CaSc2O4:Ce3t phosphors showed a single phase with a crystallite size of 1–3 μm, and its photoluminescence intensity was 10% improved compared with the as-prepared. It shows the broad 450 nm excitation peak and the green emission peak at 520 nm with a half width of 105 nm. Its temperature dependence showed the similar thermal stability with a commercial silicate phosphor. The optical simulation and the real fabrication of white LEDs with a combination of our green phosphor and one of possible orange-red phosphors demonstrated that the white LED with Sr3SiO5:Eu2t orange phosphor gives the best luminous efficacy and the appropriate color rendering index of 70 under the daylight color temperature of 6400 K.
关键词： CaSc2O4:Ce3t,White-light-emitting diode,Optical simulation,Photoluminescence,Green emission
更新于2025-09-12 10:27:22
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An approach for correcting optical paths of different wavelength lasers in diffusive medium based on Monte Carlo simulation
摘要： Near-infrared spectroscopy (NIRS) generally uses multiple wavelengths of light to obtain functional information. When different wavelengths are employed together, their optical paths are different in the medium and it can potentially cause errors. In this study, we introduced an approach of correcting optical paths when laser sources are used. Laser can be approximated by a point source in a diffusive medium and its depth depends on the wavelength. By multiplying the ratio of detected weights emitted from different point sources, they are conceptually moved to the same position. Monte Carlo simulation was implemented to accumulate required data. As an example for verifying this method, optical properties of the white matter of the brain was used. All combinations of four wavelengths (400, 550, 700, and 850 nm) and six source-detector distances (0.5 mm to 3.0 mm at intervals of 0.5 mm) were simulated. Under the same example conditions, the difference between the simulation results and this method was about ‘1.28%’. The results showed that this approach is applicable to short source-detector distance conditions.
关键词： Monte Carlo simulation,Point source approximation,Near infrared spectroscopy,Light diffusion,Optical path,Penetration depth
更新于2025-09-12 10:27:22
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Carrier transport improvement in ZnO/MgZnO multiple-quantum-well ultraviolet light-emitting diodes by energy band modification on MgZnO barriers
摘要： Ultraviolet (UV) light-emitting diodes (LEDs) based on zinc oxide (ZnO) materials have been the subject of many investigations because of their potential applications. In this study, ZnO/MgZnO multiple-quantum-well UV LEDs with graded-composition barriers were developed and numerically analyzed. The simulation results demonstrate that an optimized LED with a Mg composition graded from 24% to 2% in each triangular barrier exhibits the highest internal quantum efficiency (IQE) (88.0%) at 200 A/cm2, showing a 31.3% increase compared with the conventional LED with square barriers. This enhancement is attributed to the modified energy band structures that improve the symmetry in carrier transportation and increase the radiative recombination rate in each ZnO quantum well, thus enhancing the IQE of the device. Additionally, the different band-offset ratios of the MgZnO/ZnO and InGaN/GaN heterojunctions, which lead to the different carrier transport and electroluminescence properties of the ZnO- and GaN-based LEDs, were discussed here, providing researchers new insights into device design of ZnO-based LEDs.
关键词： Numerical simulation,Quantum barrier,Carrier transport,Zinc oxide,Light-emitting diode
更新于2025-09-12 10:27:22