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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 - Small Size Class Preserving Classification Based on Segmentation for Hyperspectral Data
摘要： Noises in hyper spectral data make it difficult to accurately classify the domains. In order to solve this problem, some filtering methods are proposed; however, filtering processes disturb small size classes and sharp boundaries. To protect the domain boundaries in hyperspectral data classification, we applied normalized cuts segmentation in the preprocessing before classification. The proposed methodologies show higher OA and AA, which means that the domain boundaries are maintained, and classification accuracies of small classes are improved. We also found that the classification accuracies are not sensitive to the number of clusters. The proposed methodology is useful for the combination of smoothing filters that show high classification performances.
关键词： normalized cuts,Hyperspectral data,small size class,edge-preserving filter,segmentation
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 - Geosynchronous Continental Land-Atmosphere Sensing System (G-Class): Persistent Radar Imaging for Earth Science
摘要： More frequent imaging of Earth system processes is recognised as one of the emerging needs in Earth observation. Conventional low Earth orbit satellites are limited in their ability to provide this, whereas satellites in geosynchronous orbit can in principle provide continuous imaging. A new mission design has been developed from studies for a previous geosynchronous radar mission concept (GeoSTARe) to improve its technical feasibility and geographical coverage, and to reinforce its science focus. This new mission (Geosynchronous-Continental Land Atmosphere Sensing System (G-CLASS)) is presented. G-CLASS is in fact a family of missions: we present a version focussed on the diurnal water cycle - G-CLASS:H2O - for which geosynchronous radar has great potential. G-CLASS:H2O is being developed as a proposal for ESA’s Earth Explorer programme.
关键词： GeoSTARe,water,radar,geosynchronous,G-CLASS
更新于2025-09-10 09:29:36
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Effects of Foreign Metal Object on Soft-Switching Conditions of Class-E Inverter in WPT
摘要： A foreign metal object will deteriorate the performance of wireless power transfer (WPT) systems and cause insecurity issues. Therefore, the in?uence principles and rules of foreign metal objects on soft-switching conditions of Class-E inverters and the performance of WPT systems are developed in this paper. The effects of different metal materials on coil parameters at different frequencies and positions are analyzed ?rst, then the effects of foreign metal objects on soft-switching conditions of Class-E inverters and the power transfer capability of WPT systems are investigated. Principle analyses and simulation results demonstrate that there are signi?cantly different effects on the soft-switching conditions and power transfer when a foreign metal object is placed near the transmitter coil or the receiver coil. In addition, the monotonicity of the variation in power transfer also depends on the position of the foreign metal object. Finally, a WPT experimental prototype with a Class-E inverter is implemented to verify the in?uence principles and rules of foreign metal objects. The experimental results are highly consistent with the principle analyses and simulation results.
关键词： foreign metal object,soft-switching conditions,Class-E inverter,wireless power transfer
更新于2025-09-09 09:28:46
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Critical Analysis Aspect of GaN HEMT Parasitic Elements and Its Effects on Power Performance of a SMPA
摘要： The study was conducted on the analysis of how the nonlinear behavior of the transistor affecting the drain efficiency could be minimized by integrating it in the output matching network of the power amplifier. In wireless communication, higher switching ability power amplifiers are a good choice for future advanced transmitters design. Minimizing all parasitic components is particularly very critical during the design of high-efficiency Switch-Mode Power Amplifiers (SMPA). To use the transistor in switching mode more efficiently, we analyzed some of the dominant parasitic components for better power performance of the transistor. Based on the proposed transistor model, a SMPA based on simplified class F architecture at 5.8 GHz using a Gallium Nitride High Electron Mobility Transistor (GaN HEMT) with the maximum output power of 47 dBm and high performance values of the PAE of 53.9% at peak with the power gain of 12 dB was designed. Load pull technique is used to find out the best load impedance of the amplifier.
关键词： drain efficiency,switching mode,load-pull,on-resistance,transistor parasitic,parasitic,Class F
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE Nordic Circuits and Systems Conference (NORCAS): NORCHIP and International Symposium of System-on-Chip (SoC) - Tallinn, Estonia (2018.10.30-2018.10.31)] 2018 IEEE Nordic Circuits and Systems Conference (NORCAS): NORCHIP and International Symposium of System-on-Chip (SoC) - An 87% Peak Efficiency, 37W, Class H Audio Amplifier with GaN Output Stage
摘要： This paper presents a novel high output power class H audio amplifier design with GaN transistors output stage. The design is implemented in 0.18-μm BCD process. Several design techniques to drive the GaN output stage and to improve the efficiency of the class H amplifier are introduced in this paper. The design consumes 706.3mW quiescent power and can deliver up to 37W peak output power to the load of 32Ω with the peak power efficiency of 87%. This design achieves the lowest THD+N ratio of -70.17dB.
关键词： bootstrap,efficiency,adaptive supply,total harmonic distortion,class h amplifier,Audio amplifier,buck converter
更新于2025-09-09 09:28:46
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Modelling dark current and hot pixels in imaging sensors
摘要： A Gaussian mixture model with a structured covariance matrix was used to analyse image data recorded by a digital sensor under darkness to model the effects of temperature and duration of exposure on the expected value and on the variance of the sensor dark current, separately for ordinary and possibly defective pixels. The model accounts for two components of variance within each latent type: random noise in each image and lack of uniformity within the sensor; both components are allowed to depend on experimental conditions. The results seem to indicate that the dependence of the expected value of dark current on duration of exposure and temperature cannot be represented by a simple parametric model. The latent class model detects the presence of at least two types of hot pixels. If we order the latent classes in decreasing order of the class weights, the corresponding expected values and variances increase. The covariance structure that emerges from our analysis has an important implication: the sign and the relative size of pixels deviations from uniformity are invariant to experimental conditions.
关键词： components of variance,dark current,hot pixels,latent class models,dark frames,Gaussian mixtures
更新于2025-09-04 15:30:14
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[IEEE 2018 24th International Conference on Pattern Recognition (ICPR) - Beijing, China (2018.8.20-2018.8.24)] 2018 24th International Conference on Pattern Recognition (ICPR) - Joint Identification-Verification Model for Visual Tracking
摘要： Similarity algorithms determine the location of the target by the similarity between the template and the candidate, the most similar candidate to the template is considered as the target in visual tracking. Similarity algorithms search the most similar candidate to the template as the current estimation for visual object. In practice, most trackers only take usage of the intra-class similarity, yet the inter-class semantic separability is ignored. In this paper, a joint identi?cation-veri?cation model is proposed to learn the similarity with the category attribute for visual tracking. This approach constructs the cost function both on the inter-class semantic separability and intra-class similarity, firstly. Then, the training dataset is fed into the network. To the end, the discriminative features are learned in the embedding space. During tracking phase, the template and candidates are fed into the network simultaneously. Thereforce, the target will be located correctly by the similarity metric between the template and candidates in the learned embedding space. We evaluate the proposed approach on the open benchmark: OTB50 and UAV123 dataset. A large number of experimental results show that the inter-class semantic separability can increase the discrimination for the similar distractors effectively, and bootstrap the tracking performances of the trackers based on the similarity learning.
关键词： identification-verification,similarity learning,inter-class separability,visual tracking
更新于2025-09-04 15:30:14
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Knockdown of FOXO6 inhibits high glucose–induced oxidative stress and apoptosis in retinal pigment epithelial cells
摘要： Oxidative stress and apoptosis in retinal pigment epithelium cells are involved in the pathogenesis of diabetic retinopathy (DR). Forkhead box class O 6 (FOXO6) is a member of the FOXO family that can regulate diabetes‐induced oxidative stress. However, the role of FOXO6 in DR has not been clarified. The aim of the present study was to investigate the effects of FOXO6 on high glucose (HG)‐induced oxidative stress and apoptosis in ARPE‐19 cells. The results showed that FOXO6 was overexpressed in clinical vitreous samples from DR patients and in HG‐induced ARPE‐19 cells. Knockdown of FOXO6 by small interfeing RNA targeting FOXO6 (si‐FOXO6) mitigated the HG‐induced the production of reactive oxygen species and malondialdehyde, as well as the inhibition of superoxide dismutase activity. Knockdown of FOXO6 reduced the rate of cell apoptosis in HG‐induced ARPE‐19 cells. The increase in bax expression and decrease in bcl‐2 expression caused by HG stimulation were reversed by si‐FOXO6 transfection. Furthermore, knockdown of FOXO6 enhanced the activation of Akt/Nrf2 pathway in HG‐stimulated ARPE‐19 cells. Taken together, suppression of FOXO6 protects ARPE‐19 cells from HG‐induced oxidative stress and apoptosis, which is in part mediated by the activation of Akt/Nrf2 pathway.
关键词： Akt/Nrf2 pathway,oxidative stress,retinal pigment epithelium cells,forkhead box class O 6,diabetic retinopathy,apoptosis
更新于2025-09-04 15:30:14
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Active contours driven by global and local weighted SPF for image segmentation
摘要： This paper proposes a new global and local weighted signed pressure force (SPF) based active contour model (ACM) to segment various types of images. First, by introducing the normalized global minimum absolute differences as the coefficients of global inner and outer region fitting centers, a new global weighted SPF (GWSPF) is defined, which makes the best of the difference information of inner and outer regions and improves segmentation performance. Second, by introducing the normalized local minimum absolute differences as the coefficients of local inner and outer region fitting centers similarly, a new local weighted SPF (LWSPF) is defined and added to the above global weighted SPF. Third, the global and local within-class variances of the image are used to weight the GWSPF and the LWSPF, which can automatically adjust the effect degrees of the GWSPF and the LWSPF. Experiments on many kinds of real-world images have validated that the proposed model is superior to popular ACMs in segmentation accuracy, in addition, it is robust to the initial curve.
关键词： active contour,LWSPF,GWSPF,global and local within-class variances
更新于2025-09-04 15:30:14