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The optical-flow approach has emerged as a major technique for estimating scene and object motion in image sequences. However, the results obtained by most optical flow techniques are strongly affected by motion discontinuities and by large illumination changes. While there do exist many separate techniques for robust estimation of optical flow in the presence of motion discontinuities and for dealing with the problems caused by illumination variations, only a few integrated approaches have been proposed. However, most of these previously proposed integrated approaches use simple models of illumination variation; a common assumption being that illumination changes by either just a multiplicative factor or just an additive factor from frame to frame, but not both. Some other previously proposed integrated approaches are limited to specialized tasks such as image registration or change recovery.To remedy this shortcoming, this paper presents a new robust approach to general motion estimation in an integrated framework. Our approach deals simultaneously with motion discontinuities and large illumination variations. Our model of illumination variation is general, in the sense that it admits both multiplicative and additive effects. q 2004 Published by Elsevier B.V.

Graphene quantum dots-embedded ZnS nanobelts showed 14-times higher photocatalytic activity than commercial ZnS.

Polymer membranes with excellent thermomechanical properties and good gas separation performance are desirable for efficient CO2 separation. A series of copolyimide membranes are prepared for the first time using PIM-PI-1, a hard segment with high CO2 permeability, and poly­(ethylene glycol)/poly­(propylene glycol) (PEG/PPG), a soft segment with high CO2 selectivity. Two different unit polymers are combined to compensate the limitations of each polymer (e.g., the fast aging and moderate selectivity of PIM-PI-1 and the poor mechanical properties and lower permeability of PEG/PPG). The corresponding PIM-(durene–PEG/PPG) membranes exhibit an excellent combination of mechanical properties and gas separation performance compared to the typical PI-PEG-based copolymer membrane. The improved mechanical property is attributed to the unique chain threading and the reinforcement between the spiro unit of PIM and the flexible PEG/PPG at the molecular level, which has not previously been exploited for membranes. The PIM-(durene–PEG/PPG) membranes show a high CO2 permeability of 350–669 Barrer and a high CO2/N2 selectivity of 33.5–40.3. The experimental results are further evaluated with theoretical results obtained from molecular simulation studies, and a very good agreement between the experimental results and simulation results is found. Moreover, the PIM-(durene–PEG/PPG) copolymer membranes display excellent anti-aging performance for up to 1 year.

A ureido-pyrimidinone (UPy)-functionalized poly(acrylic acid) grafted with poly(ethylene glycol)(PEG), designated PAU-g-PEG, was developed as a high performance polymer binder for Si anodes in lithium-ion batteries. By introducing both a ureido-pyrimidinone (UPy) unit, which is capable of self-healing through dynamic hydrogen bonding within molecules as well as with Si, and an ion-conducting PEG onto the side chain of the poly(acrylic acid), this water-based self-healable and conductive polymer binder can effectively accommodate the volume changes of Si, while maintaining electronic integrity, in an electrode during repeated charge/discharge cycles. The Si@PAU-g-PEG electrode retained a high capacity of 1,450.2 mAh g−1 and a Coulombic efficiency of 99.4% even after 350 cycles under a C-rate of 0.5 C. Under a high C-rate of 3 C, an outstanding capacity of 2,500 mAh g−1 was also achieved, thus demonstrating its potential for improving the electrochemical performance of Si anodes.

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