- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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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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Experimental studies and mathematical simulation of intermittent infrared and convective drying of sweet potato (Ipomoea batatas L.)
摘要： Intermittent infrared and convective drying (IIRCD) is a novel drying method that can enhance energy efficiency and quality of dried product. The mechanism of drying using this method is not yet fully understood. Mathematical models that describe the drying process of IIRCD for agricultural crops do not exist. In this study, a physics based mathematical model was developed to understand the mechanism of drying sweet potato using IIRCD. The model was based on shrinkage dependent diffusivity and evaporation phenomenon. COMSOL Multiphysics finite element software was employed for the model simulation. The simulation results of moisture and temperature distribution were validated by experimental drying data. The results fitted closely with experimental data. Drying of sweet potato using IIRCD was found to be more efficient in terms of final product quality compared to convective hot-air drying method.
关键词： quality of dried products,COMSOL,Physics-based model,modelling and simulation
更新于2025-09-23 15:23:52
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A path-finding toward high-efficiency penternary Cu(In,Ga)(Se,S)2 thin film solar module
摘要： The optimal p-n junction structure in a state-of-the-art Cu(In,Ga)(Se,S)2 thin-film solar module technology is investigated. For co-optimization design and path-finding, a TCAD model is developed with experimental samples. The engineerable parameters, i.e., FGa, GGIavg, and CdS thickness, are demonstrated to play a critical role in determining the p-n junction properties such as dark current characteristics Jdark(V), voltage-dependent photocurrent, localized carrier collection efficiency, and interface carrier transportation. We show the optimal Ga-grading is determined by a trade-off between the recombination loss in space charge region and the photo-carrier collection in quasi-neutral region. The optimal CdS thickness is determined by a trade-off between carrier collection efficiency, short-circuit current (JSC) loss, and Jdark(V), which depends on varied Ga-profiles. Overall, thin CdS (≦10 nm) is preferred to reduce the JSC loss in accumulated Ga-profiles, while thicker CdS is preferred to enhance the carrier collection efficiency in flatter Ga-profiles. The band alignment effect on varied Cu(In,Ga)(Se,S)2/CdS junctions is also investigated. It is found sulfur-incorporation can suppress the VOC saturation behavior at wide bandgap. For CIGSeS absorber with SS = 20% and DP =15%, the maximum VOC of 780 mV can be achieved by co-optimized Ga-profile. Furthermore, varied Ga-profiles and CdS buffer layers are explored for pathfinding. An optimal p-n junction structure shows a relative +40% efficiency improvement from 15.5% to 21.9%. This work shows the efficiency headroom of reported CIGSeS thin-film solar module technology through co-optimized CIGSeS composition gradient and buffer layer.
关键词： CIGSeS,Path-finding,Simulation,Solar cell
更新于2025-09-23 15:23:52
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Performance improvement of baffle-type solar air collector based on first chamber narrowing
摘要： This paper proposes a novel idea to optimize thermal performance of baffle-type solar air collector by narrowing the first chamber through rearranging the baffles in the collector. The collector with five chambers divided by four baffles was investigated numerically and experimentally, and the mechanism of performance improvement was revealed by flow and heat transfer analysis. The simulation results show that the width of first chamber has significant influence on thermal efficiency, while has little influence on pressure drop. The maximum thermal-efficiency growth rate can be achieved when the width of the first chamber is 200 mm with the total chamber size of 2000 mm × 1000 mm × 120 mm, and the value is up to 16.90% compared with the model with evenly distributed baffles during the Reynolds number ranges from 1.8–5.5 × 10^3. A test rig was developed at the ratio of 1:0.5 to the numerical model. Four collector models were studied under three working conditions, and effectiveness of this method is verified. The results show that the first-chamber narrowing method has relatively stable optimization effect with a thermal-efficiency growth rate ranges from 9.73% to 16.10% in the experiment. It means that this method is not sensitive to scale change and has certain adaptability.
关键词： Experimental verification,Numerical simulation,Performance optimization,First chamber narrowing,Solar air collector
更新于2025-09-23 15:23:52
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20?W 1952?nm tandem hybrid single and double clad TDFA
摘要： A simple engineering design is important for achieving high Thulium-doped ampli?er (TDFA) performance such as good power conversion, low noise ?gure (NF), scalable output power, high gain, and stable operation over a large dynamic range. In this paper we report the design, performance, and simulation of two stage high-power 1952 nm hybrid single and double clad TDFAs. The ?rst stage of our hybrid ampli?er is a single clad design, and the second stage is a double clad design. We demonstrate TDFAs with an output power greater than 20 W with single-frequency narrow linewidth (i.e. MHz) input signals at both 1952 and 2004 nm. An optical 10 dB bandwidth of 80 nm is derived from the ASE spectrum. The power stage is constructed with 10 μm core active ?bers showing a maximum optical slope e?ciency greater than 50%. The experimental results lead to a 1 dB agreement with our simulation tool developed for single clad and double clad TDFAs. Overall this hybrid ampli?er o?ers versatile features with the potential of much higher output power.
关键词： Simulation,Fiber ampli?er,Multistage,Single frequency,Fiber measurement,Thulium
更新于2025-09-23 15:23:52
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Core–Satellite Nanomedicines for <i>in Vivo</i> Real-Time Monitoring of Enzyme-Activatable Drug Release by Fluorescence and Photoacoustic Dual-Modal Imaging
摘要： It remains an unresolved challenge to achieve spatial and temporal monitoring of drug release from nanomedicines (NMs) in vivo, which is of crucial importance in disease treatment. To tackle this issue, we constructed core?satellite ICG/DOX@Gel-CuS NMs, which consist of gelatin (Gel) nanoparticles (NPs) with payloads of near-infrared fluorochrome indocyanine green (ICG) and chemo-drug doxorubicin (DOX) and surrounding CuS NPs. The fluorescence of ICG was initially shielded by satellite CuS NPs within the intact ICG/DOX@Gel-CuS NMs and increased in proportion to the amount of DOX released from NMs in response to enzyme-activated NMs degradation. For more comprehensive understanding of the drug-release profile, a theoretical model derived from computer simulation was employed to reconstruct the enzyme-activatable drug release of the ICG/DOX@Gel-CuS NMs, which demonstrated the underlying kinetics functional relationship between the released DOX amount and recovered ICG fluorescence intensity. The kinetics of drug release in vivo was assessed by administrating ICG/DOX@Gel-CuS NMs both locally and systemically into MDA-MB-231 tumor-bearing mice. Upon accumulation of ICG/DOX@Gel-CuS NMs in the tumor, overexpressed enzymes triggered the degradation of the gelatin scaffold as well as the release of DOX and ICG, which can be visually depicted with the ICG fluorescence signal increasing only in the tumor area by fluorescence imaging. Additionally, the photoacoustic signal from CuS NPs was independent from the physical status of ICG/DOX@Gel-CuS NMs and hence was utilized for real-time NMs tracking. Thus, by taking advantage of the core?satellite architecture and NMs degradability in tumor site, the DOX release profile of ICG/DOX@Gel-CuS NMs was monitored by fluorescence and photoacoustic dual-modal imaging in a real-time noninvasive manner.
关键词： core?satellite,nanomedicines,drug release in vivo,dual-modal imaging,computer simulation
更新于2025-09-23 15:23:52
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Analysis of trajectory similarity and configuration similarity in on-the-fly surface-hopping simulation on multi-channel nonadiabatic photoisomerization dynamics
摘要： We propose an “automatic” approach to analyze the results of the on-the-fly trajectory surface hopping simulation on the multi-channel nonadiabatic photoisomerization dynamics by considering the trajectory similarity and the configuration similarity. We choose a representative system phytochromobilin (PΦB) chromophore model to illustrate the analysis protocol. After a large number of trajectories are obtained, it is possible to define the similarity of different trajectories by the Fréchet distance and to employ the trajectory clustering analysis to divide all trajectories into several clusters. Each cluster in principle represents a photoinduced isomerization reaction channel. This idea provides an effective approach to understand the branching ratio of the multi-channel photoisomerization dynamics. For each cluster, the dimensionality reduction is employed to understand the configuration similarity in the trajectory propagation, which provides the understanding of the major geometry evolution features in each reaction channel. The results show that this analysis protocol not only assigns all trajectories into different photoisomerization reaction channels but also extracts the major molecular motion without the requirement of the pre-known knowledge of the active photoisomerization site. As a side product of this analysis tool, it is also easy to find the so-called “typical” or “representative” trajectory for each reaction channel.
关键词： trajectory similarity,multi-channel nonadiabatic photoisomerization dynamics,Fréchet distance,dimensionality reduction,phytochromobilin chromophore,on-the-fly surface-hopping simulation,configuration similarity,clustering analysis
更新于2025-09-23 15:23:52
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Artificial neural network modeling of a pilot plant jet-mixing UV/hydrogen peroxide wastewater treatment system
摘要： This study deals with the modeling and simulation of an efficient pilot plant photo-chemical wastewater treatment reactor. Treatment of an azo dye (i.e. direct red 23) was performed using a UV/H2O2 process in a jet mixing photo-reactor with 10-L volume. To model the reactor and simulate the treatment process, six important, influential physical and chemical factors such as nozzle angle (hN), nozzle diameter (dN), flow-rate (Q), irradiation time (t), H2O2 initial concentration ([H2O2]0), and pH, were taken into account. In this regard, artificial neural networks (ANNs) were employed as a powerful modeling methodology. Six different ANN architectures were constructed and most appropriate numbers for hidden neuron and learning iteration were determined based on minimization of the mean square error (MSE) function related to the testing data sets. Furthermore, simulation of the reactor efficiency, as well as sensitivity analysis, was performed via the cross-validation outputs. It was found that a three-layered feed-forward ANN composes ten hidden neurons, calibrated at 100th iteration using “trainlm” as learning algorithm and “tansig” and “purelin” as transfer functions in the hidden and output layers can model the process as the best case. The order of importance for variation of the key factors were indicated as [H2O2]0 > t > pH > Q > hN > dN.
关键词： dyes,simulation,wastewater treatment,Advance oxidation process,neural networks,photodegradation,batch reactor
更新于2025-09-23 15:23:52
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Numerical evaluation of the optical-splitter system efficiency using a TCO as optical splitter
摘要： In the present work, we simulate the J-V characteristic of a solar cell combination to evaluate the efficiency in an optical splitter system. Two different transparent conductive oxides (TCO) were used as splitters (ITO and SnO2:F). The spectral response of the TCOs was modeled according to Drude's theory, using different concentration values. Then, the J-V characteristics of the cells were simulated by SCAPS 1-D, using the spectra obtained for each TCO by superimposing the spectral response on the solar spectrum. The results indicate that solar cells can achieve efficiencies in the system above 17 % using ITO as splitter with a positive gain for both solar cells.
关键词： splitter system,solar cell simulation,TCO,SCAPS
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE ANDESCON - Santiago de Cali, Colombia (2018.8.22-2018.8.24)] 2018 IEEE ANDESCON - Development of a Low-Cost Pulse Oximeter Simulator for Educational Purposes
摘要： Medical instrumentation devices are crucial to determine health conditions in humans. Teaching biomedical instrumentation requires a perfect combination of practice and theory. Therefore, the use of physiological signals simulators such as a %SpO2 becomes important as a teaching strategy. The objective of this project is to develop and implement an oxygen saturation simulator, for use in the biomedical instrumentation courses. The development process began by establishing the requirements of the simulator and designing a graphical user interface to control the simulator parameters. Subsequently, a circuit capable of materializing the simulated signals from the interface was developed, together with a probe or artificial finger that was to be introduced inside the objective pulse oximeter. Finally, the systems were integrated into the simulator
关键词： simulation,low cost,Pulse oximetry,biomedical instrumentation,education
更新于2025-09-23 15:23:52