- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Numerical modelling and experimental validation of thermal history of titanium alloys in laser beam melting
摘要： During selective laser melting processes parts will heat up with each layer depending on the geometry and surrounding powder material. This leads to process boundary conditions that are not certainly defined and can induce unstable melt pool sizes. These will have an influence on surface roughness and dimensional accuracy. One way to deal with this is an individual adaptation of process parameters, but without knowing the exact thermal boundary conditions in each layer one will not be able to adapt the parameters properly. In this paper a model for prediction of the macroscopic temperature history is presented and experimentally calibrated. A sample with characteristic features like overhanging’s was designed. These samples were produced by selective laser melting and simultaneously monitored by an infrared camera to calibrate the boundary conditions of a numerical model. This lays the foundation for part individual adaption of process parameters to improve the quality of SLM parts.
关键词： Experimental Validation,Numerical Modelling,Titanium Alloys,SLM
更新于2025-09-12 10:27:22
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Scintillation experiments with non-uniformly and uniformly correlated spatially partially coherent laser beams propagating underwater
摘要： We report on experiments where non-uniformly correlated (NUC), Gaussian Schell (GSM) and Multi-Gaussian Schell (MGSM) model spatially partially coherent laser beams were propagated underwater. Two scenarios were explored: still water and mechanically agitated water. The main objective of our study was the experimental comparison of the scintillation performance among beams with different correlation functions. The results show generally increased absolute values of scintillation index for NUC beams as compared with GSM and MGSM beams. We hypothesized that this effect is related to the method of NUC beams generation. It should be noted, that the presented results document only the given experimental scenarios and show the relative comparison between GSM, MGSM and NUC beams with Gaussian used as a turbulence level benchmark. Further investigation is necessary to broaden the scope of our explorations of the propagation of uniformly correlated spatially partially coherent as well as non-uniformly correlated beam classes.
关键词： multi-Gaussian Schell model beam,Non-uniformly correlated,partial spatial coherence,scintillation,experimental validation,underwater laser propagation
更新于2025-09-12 10:27:22
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Fault diagnosis method of photovoltaic array based on support vector machine
摘要： Photovoltaic (PV) arrays are prone to various faults due to the hostile working environment. This paper presents the fault diagnosis algorithm based on support vector machine (SVM) to detect short circuit, open circuit, and lack of irradiation faults that occurred in PV arrays. By analyzing these faults and I–V characteristic curves of PV arrays, the short-circuit current, open-circuit voltage, maximum-power current, and maximum-power voltage are chosen as input parameters of SVM-based fault diagnosis algorithm. The data pre-processing methods are used to improve the quality of fault data set considering the effects of the quality on the performance of SVM-based fault diagnosis algorithm. The grid search and k-fold cross-validation methods are proposed to optimize the parameters of the SVM-based fault diagnosis algorithm. It gets test accuracy of 97% by testing the trained SVM-based fault diagnosis algorithm with 400 data. The experimental results indicate that the SVM-based fault diagnosis algorithm has higher accuracy and generalization ability than other algorithm for fault diagnosis of PV arrays.
关键词： k-fold cross-validation,PV arrays,data preprocessing,grid search,SVM-based fault diagnosis algorithm
更新于2025-09-12 10:27:22
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Coupled electrical-thermal modelling of photovoltaic modules under dynamic conditions
摘要： This paper presents a coupled electrical-thermal model for solar photovoltaic (PV) modules, under an unsteady state and various conditions, including ambient temperature, solar radiation and wind velocity. Validation shows that the electrical and thermal models present high agreement with the experimental data. The developed model after validation is then applied to investigate the distribution of thermal resistance, the in?uence of environmental conditions and cooling methods. Results show that the radiative and convective thermal resistances play a signi?cant role in PV electrical-thermal performance, while conductive thermal resistance can be neglected for simpli?cation in some cases. The results also demonstrate the effects of weather conditions including solar radiation, ambient temperature and wind velocity on PV performance vary and they need to be selected carefully during parameters design. Moreover, a dynamic estimation of different seasons and a long-term evaluation of an entire year for a speci?c PV array have been done to assess the performance of the coupled model. The simulated results are in good agreement with the experimental data in spite of the weather conditions, in which the relative errors of daily energy in four different seasons are just 1.06%e6.17%, while the average monthly energy based on the proposed model (1185.4 kWh) only deviates 4.66% from that extracted by PVsyst software (1132.6 kWh), which both verify the accuracy of the proposed model again.
关键词： Experimental validation,Performance evaluation,Photovoltaic (PV) module,Coupled electrical-thermal model
更新于2025-09-11 14:15:04
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Anion exchange polymeric sorbent coupled to high‐performance liquid chromatography with <scp>UV</scp> diode array detection for the determination of ten <i>N</i> ‐nitrosamines in meat products: a validated approach
摘要： Among mechanisms and molecules presumably involved in the carcinogenicity induced by meat consumption, the N-nitrosamines (N-NAs) are a class of compounds characteristic of processed meats. In this work, an analytical method for the determination of 10 N-Nitrosamines (N-Nitrosomorpholine, N-Nitriosomethyethylamine, N-Nitrosopyrrolidine, N-Nitrosodiethylamine, N-Nitrosopiperidine, N-Nitrosodipropylamine, N-Nitrosomethylaniline, N-Nitrosodibutylamine, N-Nitrosodiphenylamine, N-Nitrosodibenzylamine) in fresh meats and meat products was developed, optimized and validated. The method is based on optimized sample purification by solid phase extraction (anion exchange polymeric sorbent) and separation/detection by high performance liquid chromatography coupled to UV diode array detection. The validation procedure allowed to ascertaining good analytical performances in terms of sensitivity, selectivity towards interfering compounds, accuracy and robustness. The values obtained for precision (range: 4.3% - 14.4%) and recovery percentages (range: 80.8% - 95.1%) were compared to reference values indicated in the Decision No. 657/2002/EC, resulting as compliant. The measurement uncertainty (lower than 14.6%) was satisfactory for each N-NA as well.
关键词： meat,food safety,solid phase extraction,validation,diode array detection,Nitrosamines,processed meats,HPLC,carcinogenic compounds,anion exchange sorbent
更新于2025-09-11 14:15:04
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Fault Diagnosis Method of Photovoltaic Array Based on BP Neural Network
摘要： Photovoltaic arrays are prone to various failures due to long-term work. In order to quickly and accurately diagnose the type of failure of the PV array and implement online monitoring of the PV array, this paper proposes the BP neural network for PV array fault diagnosis, and proposes a network search method when training BP neural network. And the K-cross-validation method is used to select the number of hidden layer nodes. The BP neural network fault diagnosis model designed and trained by this method is proved to have high precision.
关键词： BP neural network,hidden layer nodes,fault diagnosis,K-cross-validation,Photovoltaic array
更新于2025-09-11 14:15:04
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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 - Validation of the Sentinel-3 Ocean and Land Colour Instrument (OLCI) Terrestrial Chlorophyll Index (OTCI): Synergetic Exploitation of the Sentinel-2 Missions
摘要： Continuity to the Medium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) will be provided by the Sentinel-3 Ocean and Land Colour Instrument (OLCI), and to ensure its utility in a wide range of operational applications, validation efforts are required. In the past, these activities have been constrained by the need for costly airborne hyperspectral data acquisition, but the Sentinel-2 Multispectral Instrument (MSI) now offers a promising alternative. In this paper, we explore the synergetic use of Sentinel-2 MSI data for validation of the Sentinel-3 OLCI Terrestrial Chlorophyll Index (OTCI) over the Valencia Anchor Station, a large agricultural site in the Valencian Community, Spain. High retrieval accuracy (RMSE = 0.20 g m-2) was obtained by applying machine learning techniques to Sentinel-2 MSI data, highlighting the valuable information it can provide when used in synergy with Sentinel-3 OLCI data for land product validation.
关键词： validation,Vegetation biophysical variables,Sentinel-2,Sentinel-3,canopy chlorophyll content
更新于2025-09-11 14:15:04
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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 - How does the Spatial Scale Mismatch Between in Situ and Smos Soil Moisture Evolve Through Timescales?
摘要： The SMOS (Soil Moisture and Ocean Salinity) mission, together with other passive microwave based missions (AMSR, SMAP), provides soil moisture estimates at resolutions ranging from 30 to 55 km. These estimates are validated by direct comparison to in situ measurements that typically measure over an area of a few centimeters. There exist a spatial scale mismatch between the satellite (large support) and the in situ measurements (point support), which contributes to the differences observed. Their magnitude depends on the spatial representativeness of the in situ measurements, which varies in time and with the selected location. This communication will show how the spatial scale mismatch evolves through timescales. It is characterized by using modeled, in situ and satellite soil moisture time series. Timescales, from 0.5 to 128 days, are obtained using wavelet transforms and the spatial representativeness is assessed with a new approach that uses wavelet-based correlations (WCor).
关键词： time scales,satellite validation,wavelet decomposition,soil moisture,spatial representativeness,spatial scales
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 - Preliminary Validation of Mixed-Pixel Clumping Index in the Arid and Semi-Arid Region, Western China
摘要： In this paper, the 1 km Mixed Pixel Clumping Index (MPCI) was calculated using the 30 m HJ-1A/1B CCD data in the arid and semi-arid region, Western China. To validate the result, an indirect validation method was proposed. In this method, the 1 km effective LAI was retrieved from the satellite data using the PROSAIL model first, and then corrected to the true LAI with the MPCI data. The comparison between the retrieved true LAI and the MODIS product shows a significant improvement relative to the effective LAI. The correlation R2 rise from 0.52 to 0.70 and the RMSE falls from 0.58 to 0.42. It indicates that the MPCI calculation is reasonable and valid for LAI retrieval from the satellite data.
关键词： mixed pixel,leaf area index,Clumping index,validation
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 - Land Surface Temperature Retrieval from the Infrared Measurements of Advanced Himawari Imager on Himawari-8
摘要： This work addresses Land Surface Temperature (LST) retrieval from the infrared measurements of Advanced Himawari Imager (AHI) on Himawari-8 satellite using the Generalized Split-Window (GSW) algorithm. First, a radiative transfer modeling experiment is conducted using the moderate spectral resolution atmospheric transmittance algorithm and computer model (MODTRAN) 4.0 fed with the SeeBor V5.0 atmospheric profile database to simulate the brightness temperatures in the AHI channels 14 (centered at about 11.2 μm) and 15 (centered at about 12.3 μm) related to Land Surface Emissivities (LSEs) and Total Precipitable Water (TPW). Then, the unknown coefficients of the GSW algorithm are obtained through multi-variable linear regression, in which the simulated data are grouped into several sub-ranges to improve algorithm accuracy. Next, LSTs are derived from the clear-sky AHI measurements in September 2016 over a study area with longitude from 100°E to 145°E and latitude from 15°N to 45°N, where LSEs are deduced from the MOD11C1 V6 product using the baseline fit method, and TPWs are extracted from the European Centre for Medium-range Weather Forecasts (ECMWF) reanalysis data. Finally, the derived LSTs are cross-validated with the MOD11C1 V6 product. The results show that the GSW algorithm developed in this work can accurately retrieve LST from the AHI measurements, and the error is 0.39±1.62 K against the MOD11C1 V6 product.
关键词： Land surface temperature,Advanced Himawari Imager (AHI),the Generalized Split-Window (GSW) algorithm,cross-validation
更新于2025-09-10 09:29:36