1000 resultados para environment
Resumo:
A catalyst-free synthesis of ZnO nanostructures using platinum microheaters under ambient environmental conditions has been developed. Different types of ZnO nanostructures are synthesized from the oxidization of Zn thin film by local heating. The characterization of two shapes of Pt microheaters is investigated and the relationship between the applied power for heat generation and ZnO nanostructure synthesis is investigated by local heating experiments under ambient conditions. Based on the developed heating approach, synthesis area, location, and morphologies of ZnO nanostructures can be controlled through the deposited thickness of Zn layer and applied heating voltages. Furthermore, a connected multiple-structure (Zn-ZnO-Zn) layer is synthesized using combinative multimicroheaters. © 2002-2012 IEEE.
Resumo:
This paper reviews and addresses certain aspects of Silicon-On-Insulator (SOI) technologies for a harsh environment. The paper first describes the need for specialized sensors in applications such as (i) domestic and other small-scale boilers, (ii) CO2 Capture and Sequestration, (iii) oil & gas storage and transportation, and (iv) automotive. We describe in brief the advantages and special features of SOI technology for sensing applications requiring temperatures in excess of the typical bulk silicon junction temperatures of 150oC. Finally we present the concepts, structures and prototypes of simple and smart micro-hotplate and Infra Red (IR) based emitters for NDIR (Non Dispersive IR) gas sensors in harsh environments. © 2012 IEEE.
Resumo:
University spin-out (USO) companies play an increasingly important role in generating value from radical, generic technologies, but this translation requires significant resources from other players to reach the market. Seven case studies illuminate how relationships with each type of partner can be leveraged to help the firm create value. We find that most firms in the sample are aware of the importance of corporate partners and actively seek to cultivate these relationships, but may not be taking full advantage of the resources available through nonparent academic institutions and other USOs with similar or complementary technologies. © 2013 The Authors. R&D Management © 2013 Blackwell Publishing Ltd.
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Chemical vapour deposition (CVD) grown graphene sheets were investigated using optical-pump terahertz-probe spectroscopy, revealing a dramatic variation in the photoinduced terahertz conductivity of graphene in different atmospheres. © 2012 IEEE.
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The performance of a 3×3 MIMO system using RoF-enabled DAS technology is experimentally investigated in a Non-Line-Of-Sight environment. Reduced spatial correlation and improved SNR are achieved due to the larger antenna separatio © OSA/ CLEO 2011.
Resumo:
Three lacustrine core samples were collected from Chaohu lake in December 2002 in the Yangtze delta region. The grain sizes were analyzed using a Laser Analyzer to obtain grain-size parameters. Sediment geochronology was determined in radioisotopes Cs-137 and the average sedimentary rates are 0.29cm.a(-1), 0.35 cm.a(-1) and 0.24cm-a(-1) in Cores C 1, C2 and C3, respectively. The grain-size parameters of the deposits vary regularly with the fluctuation of hydrodynamics. From 1950s to the beginning of 20th century, coarse-grained sediment was deposited, suggesting strong hydraulic conditions and high water-level periods with much precipitation; from the start of 20(th) century to latter half of 18(th) century, fine-grained sediment was deposited, indicating that weak hydraulic conditions and low water-level periods with less precipitation; before the first half of 18(th) century, coarse-grained sediment was deposited, suggesting great velocity of flow and high water-level periods of more precipitation.
Resumo:
An investigation was carried out to study the mobility and transfer of HCH-residues in Yanjia lake, Hubei, China, from 1990-1993. By sampling at different locations, the horizontal distribution of HCH-residues was determined; by sampling at different depths in the same location, the vertical mobility of HCH-residues and its penetration were measured. The vertical profiles of HCH-residues in sediment showed a gradient distribution, which was reduced with the increase in depth. This was very similar in shape to the organic carbon and nitrogen content profiles. The penetration of HCH-residues was measured as 60cm approximately. Meanwhile, water, sediment (0-12cm), benthos and benthic fish collected from the lake were analyzed to determine the transfer of HCH-residues along aquatic food chain. The BCF values of HCH-residues indicated that the bioaccumulation of HCH-residues in freshwater food chain still exsisted in spite of the banning of HCH since 1983. The maxium BCF value of HCH-residues in the liver samples of 5-year-old common carp was up to 61966 (calculated by beta-HCH).