A self-paced learning algorithm for change detection in synthetic aperture radar images

Detecting changed regions between two given synthetic aperture radar images is very important to monitor the change of landscapes, change of ecosystem and so on. This can be formulated as a classification problem and addressed by learning a classifier, traditional machine learning classification methods very easily stick to local optima which can be caused by noises of data. Hence, we propose an unsupervised algorithm aiming at constructing a classifier based on self-paced learning. Self-paced learning is a recently developed supervised learning approach and has been proven to be capable to overcome effectively this shortcoming. After applying a pre-classification to the difference image, we uniformly select samples using the initial result. Then, self-paced learning is utilized to train a classifier. Finally, a filter is used based on spatial contextual information to further smooth the classification result. In order to demonstrate the efficiency of the proposed algorithm, we apply our proposed algorithm on five real synthetic aperture radar images datasets. The results obtained by our algorithm are compared with five other state-of-the-art algorithms, which demonstrates that our algorithm outperforms those state-of-the-art algorithms in terms of accuracy and robustness

Solid state synthesis of Fe 2 P nanoparticles as high-performance anode materials for nickel-based rechargeable batteries

h i g h l i g h t s We report a new way to prepare Fe 2 P nanoparticles for the first time. Fe 2 P is firstly used as anode materials for nickel-based rechargeable batteries. The reversible discharge capacity of Fe 2 P nanoparticles is about 413 mAh g À1 . Fe 2 P nanoparticles exhibit attractive rate capability. a r t i c l e i n f

Understanding the Role of Few-Layer Graphene Nanosheets in Enhancing the Hydrogen Sorption Kinetics of Magnesium Hydride

The catalytic effects of few-layer, highly wrinkled graphene nanosheet (GNS) addition on the dehydrogenation/rehydrogenation performance of MgH₂ were investigated. It was found that MgH₂–5 wt %GNSs nanocomposites prepared by ball milling exhibit relatively lower sorption temperature, faster sorption kinetics, and more stable cycling performance than that of pure-milled MgH₂. The dehydrogenation step confirms that the Avrami exponent <i>n</i> increases from 1.22 to 2.20 by the Johnson–Mehl–Avrami (JMA) formalism when the desorption temperature is reduced from 350 °C to 320 °C and 300 °C, implying that a change in the decomposition temperature can alter the mechanism during the dehydrogenation process. For rehydrogenation, the Avrami value <i>n</i> is close to 1; further study by several models coincident with <i>n</i> = 1 reveals that the absorption process of the MgH₂–5 wt %GNSs sample conforms to the Mampel equation formulated through the random nucleation approach and that the nature of the absorption mechanism does not change within the temperature range studied. Furthermore, microstructure analysis demonstrated that the defective GNSs are distributed uniformly among the MgH₂ particles and that the grain size of the MgH₂–5 wt %GNSs nanocomposite is approximately 5–9 nm. The efficient metal-free catalytic dehydrogenation/rehydrogenation of MgH₂ can be attributed to the coupling of the nanosize effect and defective GNSs

3D hierarchical porous α-Fe2O3 nanosheets for high-performance lithium-ion batteries

To develop a long cycle life and good rate capability electrode, 3D hierarchical porous α-Fe2O3 nanosheets are fabricated on copper foil and directly used as binder-free anode for lithium-ion batteries. This electrode exhibits a high reversible capacity and excellent rate capability. A reversible capacity up to 877.7 mAh g −1 is maintained at 2 C (2.01 A g −1 ) after 1000 cycles, and even when the current is increased to 20 C (20.1 A g −1 ), a capacity of 433 mA h g −1 is retained. The unique porous 3D hierarchical nanostructure improves electronic- ionic transport, mitigates the internal mechanical stress induced by the volume variations of the electrode upon cycling, and forms a 3D conductive network during cycling. No addition of any electrochemically inactive conductive agents or polymer binders is required. Therefore, binder-free electrodes further avoid the uneven distribution of conductive carbon on the current collector due to physical mixing and the addition of an insulator (binder), which has benefits leading to outstanding electrochemical performance

Integrated 3D modeling unravels the measures to mitigate nickel migration in solid oxide fuel/electrolysis cells

Numerical modeling plays an important role in understanding the multi-physics coupling in solid oxide fuel/electrolysis cells (SOFCs/SOECs) operated at elevated temperatures. During long-term operation of SOFCs and SOECs, cell durability is limited by nickel (Ni) morphological changes and migration. To reveal the mechanisms behind these phenomena, a unified numerical model utilizing the phase-field (PF) method is integrated with a finite element (FE) multi-physics coupled heterogeneous single-cell model to quantitatively investigate the microstructure evolution of hydrogen electrodes operated in different modes. Based on the 3D microstructures of single-cell components reconstructed using the focused ion beam-scanning electron microscopy (FIB-SEM) technique, the performances of different cells and the corresponding microstructure evolutions caused by Ni coarsening and migration can be simulated under an identical framework in the FC and EC modes, taking into account the complex multi-physics coupling effects. It is shown that, in addition to conventional interfacial energies, the Ni migration driven by the electrochemical potential gradient induced by current also plays an important role in the microstructure evolution. The integrated model is also applied to the simulation of the microstructure evolution of the Ni-YSZ hydrogen electrode infiltrated with GDC nanoparticles to interpret their positive effect on the improvement of the electrode durability.Numerical modeling plays an important role in understanding the multi-physics coupling in solid oxide fuel/electrolysis cells (SOFCs/SOECs) operated at elevated temperatures

Na2Ti6O13 Nanorods with Dominant Large Interlayer Spacing Exposed Facet for High-Performance Na-Ion Batteries

As the delegate of tunnel structure sodium titanates, Na2Ti6O13 nanorods with dominant large interlayer spacing exposed facet are prepared. The exposed large interlayers provide facile channels for Na+ insertion and extraction when this material is used as anode for Na-ion batteries (NIBs). After an activation process, this NIB anode achieves a high specific capacity (a capacity of 172 mAh g−1 at 0.1 A g−1) and outstanding cycling stability (a capacity of 109 mAh g−1 after 2800 cycles at 1 A g−1), showing its promising application on large-scale energy storage systems. Furthermore, the electrochemical and structural characterization reveals that the expanded interlayer spacings should be in charge of the activation process, including the enhanced kinetics, the lowered apparent activation energy, and the increased capacity