69 research outputs found
Does China’s “Second-Child” Policy Increase Discrimination against Women in the Labor Market?
No full textM.P.P.In 2016, every Chinese couple is allowed to have at most two children, which abolished the historical “one-child” policy. However, there are reports saying that the sex discrimination in labor market is getting worse due to second-child policy. This thesis uses data from China General Social Survey to find empirical evidence on whether Chinese women’s situation in labor market is affected by this policy
The microstructure of a graphene-reinforced tennis racquet
Get PDFThe microstructure of a graphene-reinforced tennis racquet has been analysed using a combination of optical microscopy and Raman spectroscopy. It is shown that the main structural components in the racquet frame are high-strength carbon fibres in an epoxy resin matrix. It is also found that graphene-based nanoparticles are used to reinforce resin-rich regions in the shaft of the racquet at the discontinuity in the fibre tows, where the handle is joined to the racquet head. From a detailed analysis of the relative positions and intensities of the Raman G and 2D bands, it is demonstrated that the nanoparticles employed in the racquet are most probably graphite nanoplatelets which have been added to improve the mechanical properties of the resin-rich regions. The nomenclature used for describing graphene-based materials is also discussed in the context of this present study
Dependence of the reinforcement of polymer-based nanocomposites upon the nanofiller geometry
No full textThe role of the geometry of nanofillers on the mechanical properties of polymer nanocomposites, such as Young's modulus and toughness, has been reviewed based on published data in the literature. The fillers considered include carbon black (CB), carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), reinforcing either elastomers or epoxy resins that act respectively as examples of flexible and rigid polymers. The Young's modulus of nanocomposites reinforced by CB is revealed to follow the classical theories on particulate reinforcement. The Young's modulus of nanocomposites reinforced by GNPs and CNTs are analysed using composite micromechanics theories, i.e. a combination of the shear lag theory and rule of mixtures. A surprising finding is that if the Young's modulus of the nanofillers is considerably higher than that of the matrix, the Young's modulus of the nanocomposite is only dependent on the aspect ratio, volume fraction and orientation of the nanofiller, and is independent of its mechanical properties. The failure of the nanocomposites by crack propagation is analysed regarding the fracture toughness of the epoxy nanocomposites and the tear strength of elastomer nanocomposites. The addition of nanoparticles is found to improve the crack resistance through crack pinning whereby the crack front length increases by pinning at individual particles. It is revealed that the tear strength of the elastomer nanocomposites and the fracture toughness of the epoxy nanocomposites filled with either GNPs or CNTs is dominated by the pull-out of nanoparticles, while for elastomers other toughening mechanisms may also occur, such as cavitation
Combined Impacts of ENSO and IOD on Streamflow: A Case Study of the Jinsha River Basin, China
No full textThis study investigated the combined impacts of the El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on streamflow under four scenarios: neutral, pure ENSO, pure IOD, and a combination of ENSO and IOD. The Jinsha River Basin (JRB), at the head of the Yangtze River, was used as a case study. By using statistical methods such as coherent wavelet analysis (WTC), we are committed to studying what kind of impact the IOD will have, the difference in impact between ENSO and IOD at different stages, and the difference in impact between ENSO and IOD on the mean and extreme values of runoff, compared with traditional single ENSO event, to provide support for water resource management, especially for reservoir operation. The key results are as follows. (a) Both ENSO and IOD events affect annual and seasonal streamflow in the JRB. (b) The impact of pure IOD events on annual streamflow in the JRB was twice as great as that of pure ENSO events in developing years, whereas the opposite was true in decaying years. (c) The combined impact of ENSO and IOD led to a higher streamflow maximum than the annual or seasonal average streamflow. Conversely, their impact on the streamflow minima was less than 10% during both developing and decaying years, except at Zhimenda Station. (d) Overall, water shortages could be more serious in developing years than in neutral years, and much more attention should be given to flooding control in decaying years. These results can be used as a reference for water resource management concerning agricultural planning and ecological protection in the JRB
Next-Generation Wave Energy Harvesting with Dielectric Elastomer Generators
Get PDFThis article gives an overview of oceanwave-energy conversion using dielectric elastomer generators (DEGs), summarizing current developments and future insights into DEG-based renewable-energy harvesting
FOLT: Fast Multiple Object Tracking from UAV-captured Videos Based on Optical Flow
Get PDFMultiple object tracking (MOT) has been successfully investigated in computer
vision.
However, MOT for the videos captured by unmanned aerial vehicles (UAV) is
still challenging due to small object size, blurred object appearance, and very
large and/or irregular motion in both ground objects and UAV platforms.
In this paper, we propose FOLT to mitigate these problems and reach fast and
accurate MOT in UAV view.
Aiming at speed-accuracy trade-off, FOLT adopts a modern detector and
light-weight optical flow extractor to extract object detection features and
motion features at a minimum cost.
Given the extracted flow, the flow-guided feature augmentation is designed to
augment the object detection feature based on its optical flow, which improves
the detection of small objects.
Then the flow-guided motion prediction is also proposed to predict the
object's position in the next frame, which improves the tracking performance of
objects with very large displacements between adjacent frames.
Finally, the tracker matches the detected objects and predicted objects using
a spatially matching scheme to generate tracks for every object.
Experiments on Visdrone and UAVDT datasets show that our proposed model can
successfully track small objects with large and irregular motion and outperform
existing state-of-the-art methods in UAV-MOT tasks.Comment: Accepted by ACM Multi-Media 202
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