Study of multiple moving targets’ detection in fisheye video based on the moving blob model

Multimedia Tools and Applications - This paper discussed some improved algorithms for multiple moving targets detection and tracking in fisheye video sequences which based on the moving blob model....     

Contourlet-DCT based multiple robust watermarkings for medical images

Multimedia Tools and Applications - In the current medical system, the privacy and security of the medical information with respect to its transmission and storage is a key challenge. In pursuit of...     

Grain-refining and strengthening mechanisms of bulk ultrafine grained CP-Ti processed by L-ECAP and MDF

The microstructural evolution and mechanical properties of ultrafine-grained(UFG)CP-Ti after an inno-vative large-volume equal channel angular pressing(L-ECAP)and multi-directional forging(MDF)were systematically examined using monotonic tensile tests combined with transmission electron microscope(TEM)and electron backscatter diffraction(EBSD)techniques.Substantially refined and homogeneous microstructures were achieved after L-ECAP(8-pass and 12-pass)and MDF(2-cycle and 3-cycle),respec-tively,where the grain size distribution conformed to lognormal distribution.The grain refinement of 450℃L-ECAP is dominated by dynamic recrystallization(DRX)and dynamic recovery(DRV),while that of MDF is dominated by DRX.The iron impurities promote recrystallization by pinning-induced dislocation accumulation so that DRX is prone to occur at iron segregation regions during L-ECAP.The monotonic tensile results show that the strain hardening rate of CP-Ti increases with the decrease of grain size,while the continuous strain hardening ability decreases.The relationship between the average grain size and yield strength is in accordance with Hall-Petch relationship.Meanwhile,the individual strength-ening mechanisms were quantitatively examined by the modified model.The results indicate that the strengthening contribution of dislocation accumulation to yield strength is greater than that of grain refinement.     

Wetting behaviors and interfacial characteristics of molten AlxCoCrCuFeNi high-entropy alloys on a WC substrate

The wettability of molten AlxCoCrCuFeNi(x is from 0 to 1.5,mol.％)high-entropy alloys(HEA)on a WC substrate was measured using a modified sessile drop method at 1823 K in an argon atmosphere.The wetting behaviors and interfacial characteristics between HEAs and WC were studied.Good wettability with final equilibrium contact angles of 0.5°-4.6° is obtained,and addition of Al deteriorates the wettabil-ity of the HEAs.The wetting of AlxCoCrCuFeNi/WC system can be roughly divided into an initially sharp spreading stage and a subsequent steady-state phase.In the first stage,the adsorption of Cr atoms at the solid-liquid interface primarily contributes to the wetting,and the contact angle drastically reduces.However,both the wetting behavior and interfacial microstructure are determined by the Al content of the HEA in the next stage.For x≤0.5,the wetting is mainly driven by the dissolution of WC,although a few reaction products of(W,Cr)2C are observed.Moreover,an obvious dissolution pit appears at the surface of the substrate.When the Al content of x≥1,the interfacial reaction is dominant in competition with the dissolution of WC,and massive reaction products precipitate at the HEA/WC interface,which leads to the formation of a continuous reaction layer.     

Rational Design of Catalytic Centers in Crystalline Frameworks

Crystalline frameworks including primarily metal organic frameworks (MOF) and covalent organic frameworks (COF) have received much attention in the field of heterogeneous catalysts recently. Beyond providing large surface area and spatial confinement, these crystalline frameworks can be designed to either directly act as or influence the catalytic sites at molecular level. This approach offers a unique advantage to gain deeper insights of structure–activity correlations in solid materials, leading to new guiding principles for rational design of advanced solid catalysts for potential important applications related to energy and fine chemical synthesis. In this review, recent key progress achieved in designing MOF‐ and COF‐based molecular solid catalysts and the mechanistic understanding of the catalytic centers and associated reaction pathways are summarized. The state‐of‐the‐art rational design of MOF‐ and COF‐based solid catalysts in this review is grouped into seven different areas: (i) metalated linkers, (ii) metalated moieties anchored on linkers, (iii) organic moieties anchored on linkers, (iv) encapsulated single sites in pores, and (v) metal‐mode‐based active sites in MOFs. Along with this, some attention is paid to theoretical studies about the reaction mechanisms. Finally, technical challenges and possible solutions in applying these catalysts for practical applications are also presented.     

An interval programming model for continuous improvement in micro-manufacturing

Continuous quality improvement in micro-manufacturing processes relies on optimization strategies that relate an output performance to a set of machining parameters. However, when determining the optimal machining parameters in a micro-manufacturing process, the economics of continuous quality improvement and decision makers’ preference information are typically neglected. This article proposes an economic continuous improvement strategy based on an interval programming model. The proposed strategy differs from previous studies in two ways. First, an interval programming model is proposed to measure the quality level, where decision makers’ preference information is considered in order to determine the weight of location and dispersion effects. Second, the proposed strategy is a more flexible approach since it considers the trade-off between the quality level and the associated costs, and leaves engineers a larger decision space through adjusting the quality level. The proposed strategy is compared with its conventional counterparts using an Nd:YLF laser beam micro-drilling process.     

Effects of heat input on microstructure and mechanical properties of Fe–2Cr–Mo–0.12C steel

ABSTRACT

Thermal simulated specimens with the heat inputs of 20, 50 and 80?kJ/cm were used to investigate the effects of heat input on the microstructure and mechanical properties of the Fe–2Cr–Mo–0.12C pressure-vessel steel. The results indicated that the microstructures in the coarse-grained heat affected zone of tested steels with various heat inputs were mainly consisted of lath martensite and bainite ferrite. As the heat input increased, the fraction of martensite decreased and the bainite ferrite fraction increased. The toughness (tested at ?40°C) and hardness for the heat input of 50?kJ/cm were 102?J and 346?HV, respectively, which was attributed to the high-volume fraction (60%) of the high-angle grain-boundary and the fine bainite lath.

This paper is part of a thematic issue on Nuclear Materials.     

Enhanced Li‐Storage of Ni3S2 Nanowire Arrays with N‐Doped Carbon Coating Synthesized by One‐Step CVD Process and Investigated Via Ex Situ TEM

In this work, a facile strategy for the construction of single crystalline Ni₃S₂ nanowires coated with N‐doped carbon shell (NC) forming Ni₃S₂@NC core/shell arrays by one‐step chemical vapor deposition process is reported. In addition to the good electronic conductivity from the NC shell, the nanowire structure also ensures the accommodation of large volume expansion during cycling, leading to pre‐eminent high‐rate capacities (470 mAh g^?1 at 0.05 A g^?1 and 385 mAh g^?1 at 2 A g^?1) and outstanding cycling stability with a capacity retention of 91% after 100 cycles at 1 A g^?1. Furthermore, ex situ transmission electron microscopy combined with X‐ray diffraction and Raman spectra are used to investigate the reaction mechanism of Ni₃S₂@NC during the charge/discharge process. The product after delithiation consists of Ni₃S₂ and sulfur, suggesting that the capacity of the electrode comes from the conversion reaction of both Ni₃S₂ and sulfur with Li₂S.     

Ti3+ Self‐Doped Li4Ti5O12 Anchored on N‐Doped Carbon Nanofiber Arrays for Ultrafast Lithium‐Ion Storage

Omnibearing acceleration of charge/ion transfer in Li₄Ti₅O₁₂ (LTO) electrodes is of great significance to achieve advanced high‐rate anodes in lithium‐ion batteries. Here, a synergistic combination of hydrogenated LTO nanoparticles (H‐LTO) and N‐doped carbon fibers (NCFs) prepared by an electrodeposition‐atomic layer deposition method is reported. Binder‐free conductive NCFs skeletons are used as strong support for H‐LTO, in which Ti³⁺ is self‐doped along with oxygen vacancies in LTO lattice to realize enhanced intrinsic conductivity. Positive advantages including large surface area, boosted conductivity, and structural stability are obtained in the designed H‐LTO@NCF electrode, which is demonstrated with preeminent high‐rate capability (128 mAh g^?1 at 50 C) and long cycling life up to 10 000 cycles. The full battery assembled by H‐LTO@NCFs anode and LiFePO₄ cathode also exhibits outstanding electrochemical performance revealing an encouraging application prospect. This work further demonstrates the effectiveness of self‐doping of metal ions on reinforcing the high‐rate charge/discharge capability of batteries.