- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Performance enhancement of approximated model based near-field sources localisation techniques
摘要： Most of the existing near-field sources localisation methods are based on an approximated model. Making use of such an approximation brings degradation in the estimation accuracy. In this study, the authors propose a correction method to mitigate this problem and improve the estimation performance of the approximated model based methods. Simulation results show that the proposed technique can significantly improve the performance of the classical approximated model based near-field sources localisation methods.
关键词： approximated model,estimation accuracy,correction method,near-field sources localisation
更新于2025-09-23 15:21:21
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Electric field strength-dependent accuracy of TiAlN thin film composition measurements by laser-assisted atom probe tomography
摘要： Accurate quantification of absolute concentrations represents a major challenge for atom probe tomography (APT) since the field evaporation process is affected significantly by the measurement parameters. In the present work we investigate systematically the effect of laser pulse parameters on the accuracy of laser-assisted APT for a TiAlN thin film previously quantified by ion beam analysis, combining Rutherford backscattering spectrometry and time-of-flight elastic recoil detection analysis. The electric field strength is estimated from the Al2+/Al+ charge state ratio for all systematically varied measurement parameters. Subsequently, the absolute concentrations from laser-assisted APT are compared to ion beam analysis data. An increase of the electric field strength from approximately 25–28 V nm?1 improves the accuracy of absolute concentrations measured by laser-assisted APT from 11.4 to 4.1 at% for N, from 8.8 to 3.0 at% for Al and from 2.8 to 0.9 at% for Ti. Our data emphasize that the measurement accuracy of laser-assisted APT for TiAlN is governed by the electric field strength. It is shown that the smallest compositional discrepancies between ion beam analysis and APT are obtained for the maximum electric field strength of approximately 28 V nm?1 at 10 pJ laser pulse energy. This can be rationalized by considering the enhanced ionization of neutral fragments caused by the increased electric field strength.
关键词： accuracy,chemical composition,atom probe tomography,TiAlN,electric field strength
更新于2025-09-23 15:21:01
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Application of Generalized Regression Neural Network in Predicting the Performance of Solar Photovoltaic Thermal Water Collector
摘要： Solar photovoltaic thermal water collector (SPV/T-WC) is a hybrid device which converts power from the solar energy in to thermal and electrical simultaneously. The performance of such SPV/T-WC mainly depends on its electrical and thermal power output. Besides the performance of SPV/T-WC, is more sensitive to the transient nature of electrical and thermal power output. Thus a demand for predicting the performance variations in the SPV/T-WC is demand by users. Only limited performance prediction based research works are attempted in the performance prediction of the SPV/T-WC either numerically or by using cognitive models. In this study, two generalized regression neural network (GRNN) models are proposed to predict the transient performance variations in the SPV/T-WC. The two individual objectives of the ?rst and second model include the prediction of overall power output and the overall ef?ciency delivered by an SPV/T-WC system. Both the GRNN models proposed in this study consist of two inputs and single output. In order to train this GRNN model, real time experiments are conducted with stand-alone SPV/T-WC for four continuous days. Then based on such experimental data sets, GRNN models are trained, tested, and validated. The results predicted by the both GRNN models are in good agreement with the real time experimental results. The overall accuracy of the proposed GRNN models in predicting the performance is 95.36% and 96.22% respectively.
关键词： Solar,Water,Collector,Thermal,accuracy,Photovoltaic,GRNN,Prediction
更新于2025-09-23 15:21:01
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[IEEE 2018 International Conference on Radiation Effects of Electronic Devices (ICREED) - Beijing, China (2018.5.16-2018.5.18)] 2018 International Conference on Radiation Effects of Electronic Devices (ICREED) - Study on the Tracking & Pointing Accuracy Degeneration of Optical Communication System for CMOS Sensor Irradiation Damage
摘要： The CMOS sensor in space optical communication system may generate irradiation-induced noise, leading to deviation of image centroid. Based on test data, simulated defect spots have been used for calculating the value by grey-level centroid algorithm. It shows that both the amount and position of defect pixels contribute to deviation of image centroid and the accuracy decreasing.
关键词： tracking & pointing accuracy,CMOS sensor,optical communication,gray centroid algorithm,irradiation damage
更新于2025-09-23 15:21:01
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Laser frequency combination tuning and locking technology in resonant optical gyro
摘要： Generally, resonant optical gyroscopes (ROG) based on the Sagnac effect are very sensitive to the changes of temperature and optical power, which directly affects the output of the gyroscope. To improve the frequency lock-in accuracy and thermal stability of ROG system, the technology of laser frequency combination tuning and locking is proposed and experimentally demonstrated. Using the characteristics of voltage and temperature tuning wavelength of semiconductor laser, the output frequency range of laser is increased, the temperature control system of the resonant cavity can be removed and the gyro can never be unlocked in theory. In addition, the frequency lock-in accuracy under light power fluctuation is improved. Using this technique, a long-term (1-h) bias stability of 24.7?°/h is observed. Moreover, the weight and volume of the ROG are greatly reduced.
关键词： Resonant optical gyroscope,Frequency lock-in accuracy,Laser frequency combination tuning,Thermal stability,Light power fluctuation
更新于2025-09-23 15:21:01
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Two-dimensional transition metal dichalcogenides mediated long range surface plasmon resonance biosensors
摘要： Two-dimensional transition metal dichalcogenides (TMDCs), as promising alternative plasmon supporting materials to graphene, exhibit potential applications in sensing. Here, we propose a TMDCs-mediated long range surface plasmon resonance (LRSPR) imaging biosensor, which shows tremendous improvements in both imaging sensitivity (> ×2) and detection accuracy (> ×10) as compared to conventional surface plasmon resonance (cSPR) biosensor. It is found that the imaging sensitivity of the LRSPR biosensor can be enhanced by the integration of TMDC layers, which is di?erent from the previously reported graphene-mediated cSPR imaging sensor whose imaging sensitivity decreases with the number of graphene layers. This imaging sensitivity enhancement e?ect for the TMDCs-mediated LRSPR sensor originates from the propagating nature of the LRSPR at both interfaces of sensing medium/gold and gold/cytop layer (with matching refractive index as sensing medium). By tuning the thickness of gold ?lm and cytop layer, it is possible to achieve optimized imaging sensitivity for LRSPR sensor with any known integrated number of TMDC layers and the analyte refractive index. The proposed TMDCs-mediated LRSPR imaging sensor could provide potential applications in chemical sensing and biosensing applications.
关键词： detection accuracy,biosensor,long range surface plasmon resonance,Two-dimensional transition metal dichalcogenides,imaging sensitivity
更新于2025-09-23 15:21:01
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Evaluation of marginal and internal fit of acrylic bridges using optical coherence tomography
摘要： Background: The potential of non-invasive optical coherence tomography (OCT) as a tool for assessment of fit of indirect reconstructions is not fully explored. Objectives: The objectives were to investigate the feasibility and validity of OCT, and to measure the internal and marginal fit of acrylic bridges fabricated using direct and indirect digitalization. Methods: The accuracy of the employed swept source OCT (wavelength: 1310nm) was assessed by comparing with an object with known dimensions. Validity was assessed by comparing OCT measurements on replica, mimicking the cement film thickness, with stereomicroscopic measurements. The reconstructions were placed on the abutments without cementation. The internal and marginal fit of acrylic bridges from direct and indirect digitalization techniques were then assessed by obtaining 5 OCT B-scans per abutment tooth at pre-defined positions located 250 μm apart. The marginal and internal cement gaps were measured using image-processing software (ImageJ). Mean and standard deviation were calculated for both groups and t-test assuming unequal variances was carried out. The level of significance was defined at 0.05. Results: A strong linear correlation (r = 0.865) between OCT and stereomicroscopy was found. T-test showed significantly (P < 0.01) better internal fit of bridges made from indirect digitalization, but no difference in marginal fit. Conclusion: OCT is a feasible and valid tool for investigating internal and marginal fit of acrylic dental reconstructions. Better internal fit was observed in bridges fabricated using the direct digitalization technique. No difference in marginal fit was found between the two fabrication methods.
关键词： Accuracy,Dental marginal fit,Replica technique,Optical coherence tomography,Dental internal fit,Acrylic Resins
更新于2025-09-23 15:21:01
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[IEEE 2017 5th RSI International Conference on Robotics and Mechatronics (ICRoM) - Tehran, Iran (2017.10.25-2017.10.27)] 2017 5th RSI International Conference on Robotics and Mechatronics (ICRoM) - Robustness Enhancement of optical flow sensors accuracy to surface texture variations using point tracking algorithm
摘要： Novel architecture of high precision localization using optical flow sensor (OFS) combined with Iterative Point Tracking Algorithm (IPTA) is proposed. This work focuses on attenuation of OFS' sensitivity dependency on texture of surface over which sensor is moving. The aim for the design of experimental setup is to verify how much a robustness of OFS’s sensitivity on various surfaces improves. In this regard, four different surfaces' texture including iron, paper, textile and granite stone is opted. Experimental results indicate that sensor's resolution via IPTA on surfaces of iron, paper, textile and granite stone respectively equal to 382, 460, 528 and 448 CPI. Optimal value of the algorithm parameters is calculated via Genetic Algorithm (GA). We show that IPTA is one of the effective algorithms that can enhance the robustness of OFS' resolution to surface's texture variations.
关键词： Optical flow sensor,point tracking algorithm,Surface Texture,high accuracy planar localization,Genetic algorithm
更新于2025-09-23 15:21:01
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Application and Validation of a Model for Terrain Slope Estimation Using Space-Borne LiDAR Waveform Data
摘要： The terrain slope is one of the most important surface characteristics for quantifying the Earth surface processes. Space-borne LiDAR sensors have produced high-accuracy and large-area terrain measurement within the footprint. However, rigorous procedures are required to accurately estimate the terrain slope especially within the large footprint since the estimated slope is likely affected by footprint size, shape, orientation, and terrain aspect. Therefore, based on multiple available datasets, we explored the performance of a proposed terrain slope estimation model over several study sites and various footprint shapes. The terrain slopes were derived from the ICESAT/GLAS waveform data by the proposed method and five other methods in this study. Compared with five other methods, the proposed method considered the influence of footprint shape, orientation, and terrain aspect on the terrain slope estimation. Validation against the airborne LiDAR measurements showed that the proposed method performed better than five other methods (R2 = 0.829, increased by ~0.07, RMSE = 3.596?, reduced by ~0.6?, n = 858). In addition, more statistics indicated that the proposed method significantly improved the terrain slope estimation accuracy in high-relief region (RMSE = 5.180?, reduced by ~1.8?, n = 218) or in the footprint with a great eccentricity (RMSE = 3.421?, reduced by ~1.1?, n = 313). Therefore, from these experiments, we concluded that this terrain slope estimation approach was beneficial for different terrains and various footprint shapes in practice and the improvement of estimated accuracy was distinctly related with the terrain slope and footprint eccentricity.
关键词： terrain slope,Geoscience Laser Altimeter System (GLAS),estimation accuracy,footprint diameter,Light Detection and Ranging (LiDAR)
更新于2025-09-23 15:21:01
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Comprehensive Remote Sensing || Accuracy and Area Estimation
摘要： A key strength of remote sensing, and one of the main reason for its usage, is the provision of spatially exhaustive (wall-to-wall) coverage of a region of interest. Classification and interpretation of the remote sensing data allow for thematic mapping of features present in the region. However, mapping complex and often spatially continuous surface conditions into a set of discrete map categories is bound to result in some of the map units being erroneous. The magnitude of errors will determine the reliability, usage, and interpretation of the map, which is why map users and producers have a direct interest in communicating and understanding the quality of maps. This is the primary reason for the tradition within the remote sensing community of conducting map accuracy assessments (terms in italic are explained in the Terminology section). The basis of an accuracy assessment is the comparison of the map and a sample of observations of reference conditions at certain selected locations. The sample is selected by probability sampling if the locations of the sampling units are selected such that the likelihood of a unit (a pixel for example) being included in the sample is known and greater than zero (Stehman, 2001). A probability sample allows for inference of the accuracy of the map for the entire population, which in this case is the collection of map units from which the sample is selected. For example, consider the following common scenario: a land-cover map has been constructed over specific region and a set of units have been selected by simple random sampling. If identifying land-cover reference conditions at each location in the sample, the overall accuracy of the map can easily be computed as the ratio of correctly classified units to the total number of units in the sample. The overall accuracy is a measure of the probability that a random map unit is correctly classified—not just a random map unit in the sample, but of all units of the map. This holds true because the sample was selected by probability sampling. As explained in section “Design-Based Inference”, accuracy measures specific to the individual map categories are also easily computed.
关键词： thematic mapping,probability sampling,remote sensing,accuracy assessment,error matrix
更新于2025-09-23 15:21:01