Recursos de colección

HKUST Institutional Repository (5.016 recursos)
Repository of Hong Kong University of Science and Technology. Managed by the HKUST Library.

Mostrando recursos 1 - 11 de 11

4. Composite materials with negative elastic constants - Sheng, Ping; Xiao, Rong-Fu; Wen, Wei-Jia; Zheng, You Liu
This invention provides a composite material having a matrix of structural material containing embedded zones of soft elastic material and zones of solid relatively high density material within the soft elastic material. By selecting a particular resonance frequency for the subunits of soft elastic material and solid high density material, frequencies just lower than the resonance frequencies will be unable to propagate through the material and be strongly reflected or absorbed. Such material may be used in the manufacture of filters or shields against particular target frequencies. Subunits having a variety of resonance frequencies may provide a broader range of...

5. Light emitting material - Xu, Gui C.; Sou, Philip Iam-Keong; Wong, Kam-Sing; Wang, Hong; Yang, Zhi-Yu; Wong, George K. L.
A novel photoluminescent material is disclosed comprising an active layer of ZnS1-xTex deposited directly onto a substrate by molecular beam epitaxy. The emitted light is primarily in the blue end of the spectrum. The substrate may be GaAs or more preferably Si. Deposition the material directly onto Si allows the material to be used to manufacture integrated semiconductor light emitting devices. High efficiency may be obtained at low concentrations of Te(0.01?x?0.07) which allow good lattice matching of the active layer to an Si substrate.

6. Visible-blind UV detectors - Sou, Philip Iam-Keong (???); Ma, Zhaohui (???); Man, Choi Lai (???); Wong, Kam-Sing (???); Yang, Zhi-Yu (???); Wong, George K. L. (???)
UV detectors with high responsivities for wavelengths shorter than 400nm are very important for applications such as flema monitoring, pollutant detection and UV astronomy. Conventionally, photo-multiplier tubes and silicon p-i-n photodiodes are the devices used for UV detectors. However, conventional photo-multiplier tubes have been satisfactory only in the past and the more preferred silicon p-i-n photodiodes have lower quantum efficiency. In all previous semiconductor-based UV photodetectors, there is a problem of lack of a suitable lattice-matched substrate and therefore inevitably results in high density of misfit dislocations and traps present in these structures. This then severely limits the response time...

7. Planar band gap materials - Wen, Wei-Jia; Sheng, Ping; Chan, Che-Ting; Ge, Wei-Kun; Zhou, Lei; Li, Jensen
This improved material relates to novel planar materials having band gap properties, and in particular to such materials formed with fractal patterns. Band gap materials are ideal for shielding electromagnetic (EM) radiation as they have a gap in the transmission band thus blocking transmission of EM radiation. Their conventional three-dimension crystal structures and properties restricted their size and corresponding wavelength range for practical applications. Usually, they are too large and bulky, and must be of the same order of the wavelength of the band gap. These new planar band gap materials comprise of a conductive fractal pattern formed on a non-conducting...

8. Electrorheological fluids - Sheng, Ping; Wen, Wei-Jia; Chan, Che-Ting; Ge, Wei-Kun; Yang, Shihe
Electrorheological(ER) fluids are of high interest because potentially they can provide simple, quiet, and fast interfaces between electrical controls and mechanical systems. However, a problem with ER fluids to date is that the yield strength is too low for many practical applications. The main drawback of this approach is that the large dielectric contrast between the solid particles and the fluid can give rise to a large electrical current and breakdown. In the present invention, a new idea is proposed whereby the extremely large electric field usually present in a electrolytic double layer is harnessed to advantage, giving yield strength of...

9. Three-dimensional H-fractal bandgap materials and antennas - Wen, Wei-Jia; Sheng, Ping; Hou, Bo
Photonic band gap (PBG) materials are those periodic composites that possess spectral gaps in the frequency spectrum, in which electromagnetic waves cannot propagate in any direction within the material. Conventional PBG are based on Bragg scattering which limits the size of PBG structures for low-frequency applications. This invention relates to novel three-dimensional (3D) band gap composite material having band gap properties and in particular to such materials in which at least one of the components is formed with 3D H-fractal configurations. 3D fractal can shield much longer electromagnetic (EM) wavelength to generate sub-wavelength stop band gaps with much smaller structure dimension...

10. Lithium-ion battery incorporating carbon nanostructure materials - Tang, Zi-Kang; Sheng, Ping; Liang, Qi; Wang, Ning; Chan, Che-Ting
A lithium ion battery is disclosed in which the negative electrode material comprises carbon nanostructures having no dimension greater that 2μm. The battery has a high reversible capacity of the order of 400 mAh/g to 5000 mAh/g which can be maintained over a long cycle-life (at least 30 cycles). The carbon nanostructures may be mixed with graphite to improve conductivity. The carbon nanostructures may be synthesized using an AFI template material followed by calcination.

11. Method for the deposition of diamond on a substrate - Hiraoka, Hiroyuki; Latsch, Stefan A.; Xiao, Rong-Fu
A method is disclosed for the deposition of crystalline diamond on a substrate such as a silicon wafer. A polymer (for example poly(methylmethacrylate)) is provided as a target for laser ablation using for example an ArF excimer laser or an Nd-Yag laser. The laser ablation is performed in the presence of a reactive gas such as oxygen or hydrogen. The substrate is heated to a temperature of between 450 and 700 degrees celsius.