| 1. |
- Deng, Juan, et al.
(författare)
-
Hierarchical Segmentation of Multitemporal RADARSAT-2 SAR Data Using Stationary Wavelet Transform and Algebraic Multigrid Method
- 2014
-
Ingår i: IEEE Transactions on Geoscience and Remote Sensing. - 0196-2892 .- 1558-0644. ; 52:7, s. 4353-4363
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper is to develop a new effective method for hierarchical segmentation of multitemporal ultrafine-beam synthetic aperture radar (SAR) data in urban areas. Multitemporal RADARSAT-2 ultrafine-beam high-resolution horizontal transmit and horizontal receive-Synthetic Aperture Radar (HH-SAR) images acquired in the rural-urban fringe of the Greater Toronto Area during the summer of 2008 are selected for this research. Stationary wavelet transform (SWT) and algebraic multigrid (AMG) method are proposed for segmentation of SAR data. SWT is applied for decomposition of multitemporal SAR images in image preprocessing. The hierarchical and matrix-based AMG method is applied for segmentation. A pyramid of fine-to-coarse grids is constructed by iteration of selecting representative pixels and calculating the interpolation matrix between a fine-level grid and a coarse-level grid. When the pyramid is completed, segments are determined by a top-down scanning based on the interpolation matrices. The AMG techniques provide a complete hierarchical segmentation of SAR data. The experimental results show that our method produces higher accuracy than eCognition.
|
|
| 2. |
|
|
| 3. |
- Lin, Li-Li, et al.
(författare)
-
Assignments of Inelastic Electron Tunneling Spectra of Semifluorinated Alkanethiol Molecular Junctions
- 2011
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:41, s. 20301-20306
-
Tidskriftsartikel (refereegranskat)abstract
- The peculiar experimental inelastic electron tunneling spectra of a series of hexadecanethiol molecular junctions have finally been reproduced by first-principles simulations. It is found that the debated spectral profile around 0.38 eV indeed originated from the C-H stretching vibration associated with at least two terminal methylene groups close to the sulfur atom. The intensity of this spectral peak becomes dominant, as observed in the experiments when the molecule is titled -40 degrees relative to the normal of the electrode surface, which is due to the opening of a new tunneling pathway bypassing the end sulfur atom. The dependence of this strong vibrational feature on the titled angle of the molecule is predicted with the help of the concept of effective coupling energy. The degree of the fluorination on the inelastic electron tunneling spectrum of hexadecanethiol molecules has also been discussed in detail.
|
|
| 4. |
|
|
| 5. |
- Pan, Liang, et al.
(författare)
-
a A Resistance-Switchable and Ferroelectric Metal Organic Framework
- 2014
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 136:50, s. 17477-17483
-
Tidskriftsartikel (refereegranskat)abstract
- The ever-emerging demands on miniaturization of electronic devices have pushed the development of innovative materials with desired properties. One major endeavor is the development of organic- or organic-inorganic hybrid-based electronics as alternatives or supplements to silicon-based devices. Herein we report the first observation of the coexistence of resistance switching and ferroelectricity in a metal-organic framework (MOF) material, [InC16H11N2O8]center dot 1.5H(2)O, denoted as RSMOF-1. The electrical resistance of RSMOF-1 can be turned on and off repeatedly with a current ratio of 30. A first-principles molecular dynamics simulation suggests that the resistive switching effect is related to the ferroelectric transition of N center dot center dot center dot H-O center dot center dot center dot H-N bridge-structured dipoles of the guest water molecules and the amino-tethered MOF nanochannel. The discovery of the resistive switching effect and ferroelectricity in MOFs offers great potential for the physical implementation of novel electronics for next-generation digital processing and communication.
|
|
| 6. |
- Qian, Bin, et al.
(författare)
-
Assembled nano-structures from micron-sized precursors
- 2014
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:58, s. 30754-30757
-
Tidskriftsartikel (refereegranskat)abstract
- Oriented assembly of small crystals to form larger structures are common in nature and full understanding and control of such process would be beneficial for the forthcoming nano-technologies. Such bottom-up assembly of nano-structures most often requires a precursor of nano-sized crystals. Here we demonstrate a novel laser sintering process that can rupture a submicron-sized zirconia precursor into nano-sized crystals, followed by a rapid oriented assembly of these small crystals. A detailed structure study has been carried out to understand the complex process and a model has been proposed. Such a process sheds light on a new way of fabricating nano-materials using commercialized oxide materials.
|
|
| 7. |
|
|
| 8. |
- Sun, Jia-Bin, 1948, et al.
(författare)
-
Important Role for Fc gamma RIIB on B Lymphocytes for Mucosal Antigen-Induced Tolerance and Foxp3(+) Regulatory T Cells
- 2013
-
Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 191:8, s. 4412-4422
-
Tidskriftsartikel (refereegranskat)abstract
- Fc gamma RIIB, the only Fc gamma R expressed on B cells, is important in the maintenance of immunological tolerance to self-Ags. In this study, we investigated the role of Fc gamma RIIB in Ag-specific CD4 T cell tolerance induced by mucosally administered Ag (OVA) coupled to cholera toxin B subunit (Ag/CTB) or given alone. We found that sublingual administration of Ag/CTB conjugate or intragastric administration of a >100-fold higher dose of Ag alone efficiently suppressed parenteral immunization-induced Ag-specific T cell proliferation and delayed-type hypersensitivity responses in Fc gamma RIIB-expressing wild-type (WT), but not Fc gamma RIIB-/-, mice. Such mucosally induced tolerance (oral tolerance) associated with induction of Ag-specific Foxp3(+) regulatory T cells was restored in Fc gamma RIIB-/- mice by adoptive transfer of either WT B cells or WT dendritic cells before the mucosal Ag/CTB treatment; it was even more pronounced in mu MT mice that received Fc gamma RIIB-overexpressing B cells before treatment. Furthermore, cell transfer in either WT or mu MT mice of WT but not Fc gamma RIIB-/- B cells pretreated for 1 h in vitro with Ag/CTB conjugate induced Ag-specific immunological tolerance, which was further enhanced by adoptive transfer of WT B cells pretreated with anti-Ag IgG immune complexed Ag/CTB. We conclude that Fc gamma RIIB expression on B cells, in addition to dendritic cells, is important for mucosal induction of Ag-specific immune tolerance.
|
|
| 9. |
- Zou, Ji, et al.
(författare)
-
A top-down approach to densify ZrB2-SiC-BN composites with deeper homogeneity and improved reliability
- 2014
-
Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 249, s. 93-101
-
Tidskriftsartikel (refereegranskat)abstract
- A novel top down approach was developed to fabricate dense ZrB2-SiC-BN (ZSN) composites with a fine-grained (<1 mu m) microstructure using coarse-grained (similar to 10 mu m) ZrN and Si precursors that reacted with fine (similar to 0.5 mu m) B4C powders at 1850 degrees C. The results show that the reaction and densification mechanisms acting during sintering could be separated or happen simultaneously by changing the pressure loading strategy. Loading cycles not only have a substantial influence on the microstructure homogeneity and the strength reliability of as sintered composites, but might alter the electric current path during the Spark Plasma Sintering process as well. A residual compressive stress of 361 MPa, generated upon the SiC grains in the ZSN composites, was measured by Raman spectroscopy. The fine SiC grains tended to form larger clusters in the dense microstructure if the loading cycle is inappropriate, which was further employed to interpret the observed scattering of strength values in one batch of ZSN. The 48ZrB(2)-24SiC-28BN (number in vol%) composite has an average strength of 473 MPa, which was 94% of that of in situ densified ZrB2-SiC ceramics (ZS). Considering the corresponding Youngs modulus was only half of that for ZS, the in situ ZSN composite owns a better mechanical strain tolerance.
|
|
