Active weighted mapping-based residual convolutional neural network for image classification

Multimedia Tools and Applications - In visual recognition, the key to the performance improvement of ResNet is the success in establishing the stack of deep sequential convolutional layers using...     

DTN: Deep triple network for topic specific fake news detection

Detection of fake news has spurred widespread interests in areas such as healthcare and Internet societies, in order to prevent propagating misleading information for commercial and political purposes. However, efforts to study a general framework for exploiting knowledge, for judging the trustworthiness of given news based on their content, have been limited. Indeed, the existing works rarely consider incorporating knowledge graphs (KGs), which could provide rich structured knowledge for better language understanding.In this work, we propose a deep triple network (DTN) that leverages knowledge graphs to facilitate fake news detection with triple-enhanced explanations. In the DTN, background knowledge graphs, such as open knowledge graphs and extracted graphs from news bases, are applied for both low-level and high-level feature extraction to classify the input news article and provide explanations for the classification.The performance of the proposed method is evaluated by demonstrating abundant convincing comparative experiments. Obtained results show that DTN outperforms conventional fake news detection methods from different aspects, including the provision of factual evidence supporting the decision of fake news detection.     

3D printing boehmite gel foams into lightweight porous ceramics with hierarchical pore structure

We herein report a novel hierarchically porous ceramic foams derived from boehmite gel foams, which possess both high porosity and superior strength. The gel foams show excellent printability due to its predominant stability, high yield stress and storage modulus, which endows such foam material ideal ink for 3D printing lightweight and complex-shape materials via direct ink writing approach. The 3D printed ceramic foams possess programmable architecture assembled by porous filaments, uniform macro-pores with tunable size in the range of 4∼70 μm, as well as nanoscale pores in cell wall, after sintering at relatively low temperature of 1200–1300 °C. In this way, ceramic foams with high strength were achieved, attributed to the tiny grains, large amount of grain boundaries, uniform pores and hierarchical pore structure. Notably, the foams sintered below 1200 °C have significant advantage on specific surface area, which could reach up to 300-400 m²/g.     

Evaluation of isotopic boron (11B) for the fabrication of low activation Mg11B2 superconductor for next generation fusion magnets

In this study, we analyze the properties of boron isotope (¹¹B)-rich powders from three different sources, that is, American, Cambridge, and Pavezyum, to fabricate the bulk Mg¹¹B₂ superconductors and evaluate their superconducting properties. While ¹¹B-rich powder is an essential precursor to fabricate Mg¹¹B₂ superconductors for fusion magnet applications, the properties of the ¹¹B powder turned out to be critical to determine the quality of the final superconducting product. Therefore, appropriate control of processing conditions is needed to comply with the requirements of the nuclear fusion application. Analysis of the B isotope ratio by accelerator mass spectroscopy and neutron transmission revealed that all three types of powder are enriched with ¹¹B to better than 99 at % quality. In addition, Pavezyum's ¹¹B shows the lowest crystallinity and smallest crystalline domain size as evidenced by the high-resolution X-ray diffractometer and scanning electron microscopy. The chemical states of the boron isotope investigated with near edge X-ray absorption fine structure spectroscopy and X-ray photoemission spectroscopy also reveals that Pavezyum boron has amorphous structure. Mg¹¹B₂ bulks and multi-filamentary (12-filament) wires have been manufactured, sintered at different temperatures and characterized via the transport critical current density. The wire with Pavezyum ¹¹B shows three times higher current carrying capacity at a particular magnetic field compared to the wire using Cambridge ¹¹B and hence, Pavezyum ¹¹B boron has the potential for manufacturing fusion grade Mg¹¹B₂ based magnets. The results of this study demonstrated that Boron powders with higher purity, smaller grain size and lower crystallinity are critical for improving the superconducting and electronic properties of Mg¹¹B₂ samples fabricated from the powder. Thus, the low-neutron-activation Mg¹¹B₂ is possibly an affordable and technically viable candidate to replace NbTi superconductors in the low field poloidal field and correction coils for the next-generation fusion reactors.     

A comparative study of catalytic behaviors of Mn,Fe, Co,Ni, Cu and Zn–Based catalysts in steam reforming of methanol,acetic acid and acetone

This study investigated the distinct catalytic behaviors of mono Mn, Fe, Co, Ni, Cu and Zn catalysts in the reforming of the small organics including methanol, acetic acid and acetone. The results showed that Mn, Fe or Zn-based catalysts showed almost no activity for steam reforming of either methanol, acetic acid or acetone, due to their low capacity to break the chemical bonds of the organics or to activate steam. Co and Cu-based catalysts were generally active for steam reforming of methanol. Nevertheless, Co-based catalysts promoted methanol decomposition to form a substantial amount of CO. Alumina as a support remarkably influenced catalytic stability of the catalyst. The unsupported Cu catalyst showed a much lower stability than Cu/Al₂O₃. Nevertheless, the unsupported Ni was more stable than Ni/Al₂O₃ catalyst, due to its high resistivity towards coking. The unsupported Co, however, was prone to coking. The C/H ratios in the coke formed over the unsupported and alumina-supported Ni or Co catalysts were distinct, indicating the involvement of alumina in the coking process. In addition, Ni and Co catalysts behaved differently. Ni/Al₂O₃ showed a superior stability than Co/Al₂O₃ in steam reforming of acetone. The coke formed on Ni/Al₂O₃ was more aromatic than that over Co/Al₂O₃ catalysts while morphologies of coke (nanotubes over Ni/Al₂O₃ versus fibrous coke over Co/Al₂O₃) were also different.     

Effects of sintering on the mechanical and ionic properties of ceria-doped scandia stabilized zirconia ceramic

The effect of conventional sintering from 1300 to 1550 °C on the properties of 1 mol% ceria-doped scandia stabilized zirconia was investigated. In addition, the influence of rapid sintering via microwave technique at low temperature regimes of 1300 °C and 1350 °C for 15 min on the properties of this zirconia was evaluated. It was found that both sintering methods yielded highly dense samples with minimum relative density of 97.5%. Phase analysis by X-ray diffraction revealed the presences of only cubic phase in all sintered samples. All sintered pellets possessed high Vickers hardness (13–14.6 GPa) and fracture toughness (~3 MPam^1/2). Microstructural examination by using the scanning electron microscope revealed that the grain size varied from 2.9 to 9.8 µm for the conventional-sintered samples. In comparison, the grain size of the microwave-sintered zirconia was maintained below 2 µm. Electrochemical Impedance Spectroscopy study showed that both the bulk and grain boundary resistivity of the zirconia decreases with increasing test temperature regardless of sintering methods. However, the grain boundary resistivity of the microwave-sintered samples was higher than the conventional-sintered ceramic at 600 °C and reduced significantly at 800 °C thus resulting in the enhancement of electrical conduction.     

New insight into the modification of Li-rich cathode material by stannum treatment

In this work, Sn is used to dope the Li-rich cathode material to improve the electrochemical performance of Li ion battery. After Sn treatment, the lattice parameters a, c and lattice volume V become larger. Compared with the pristine sample, the Sn-contained samples show longer plateaux at about 4.5 V in the first charging process, which means that Sn can activate the Li₂MnO₃ component. Meanwhile, with appropriate content of Sn doping, the sample exhibits enhanced rate capability and cycling stability. Especially, the sample S10 shows the best electrochemical performance, with a capacity retention of 88.66% after 100 cycles at 1 C (1 C=250 mA g⁻¹). The mechanisms of Sn doping have also been investigated. The increased activation of Li₂MnO₃ is due to the improved conductivity of Li₂MnO₃ phase by Sn doping, and the enhanced electrochemical performance is mainly ascribed to the increased ability of Li ion diffusing into bulk phase and the improved structure stability during the prolonged charge-discharge cycles. It is suggested that Sn doping is an effective way to improve the electrochemical performance of Li-rich cathode material.     

Synthesis of octahedral Cu2O microcrystals assisted with mixed cationic/anionic surfactants

Octahedral Cu₂O microcrystals were successfully prepared in aqueous solution using hydrazine as the reducing agent and assisted with mixed cationic/anionic surfactants. The products were characterized by means of scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectrum. The formation mechanism of obtained octahedral Cu₂O microcrystals was discussed.     

Formation of oxynitride layers on titanium alloys by gas diffusion treatment

Titanium alloys were oxynitrided in controlled nitrogen-oxygen gas atmospheres between 650 °C and 950 °C for 5 h to 10 h with two different techniques of gas diffusion treatment. One technique was performed in an oxygen-containing (oxygen amount ≥ 0.4 %) nitrogen environment. The other technique was performed in a deoxygenated (oxygen amount < 0.01 % to 0.0005 %) nitrogen environment with subsequent cooling in an oxygen-containing nitrogen environment (with an oxygen pressure of 1 Pa). The surface microhardness of oxynitrided samples increased due to the strengthening effect of titanium oxynitrides (TiN_xO_y). The maximum microhardness of the titanium oxynitrides was obtained with a near-equiatomic composition of nitrogen and oxygen in TiN_xO_y under optimal oxygen partial pressure and temperature-time conditions.     

Capacity analysis and MAC enhancement for UWB broadband wireless access networks

We analyze the capacity of ultra-wide band (UWB) wireless access networks supporting multimedia services by calculating the number of multimedia connections that can be supported in a UWB access network with IEEE 802.15.3 Medium Access Control (MAC) protocol, considering the overheads from different layers. We then propose how to increase the capacity by improving the MAC protocol design and parameter setting. We also quantify the effectiveness of different approaches and derive the appropriate MAC protocol parameters such as the duration of contention period and contention free period in a superframe. Simulation results are given to demonstrate the accuracy of the analysis.