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  • 1
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physical Chemistry 56 (2005), S. 221-254 
    ISSN: 0066-426X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Physics
    Notes: Molecular structures during chemical processes are crucial for predicting molecular reactivity and reaction mechanisms. Using a laser pulse as an internal clock for starting fundamental chemical processes, molecular structural dynamics can be characterized by coherent vibrational motions and by incoherent transitions between different intermediate states. Recent developments in pulsed X-ray facilities allow structural determination of discrete excited states and reaction intermediates using laser-initiated time-resolved X-ray absorption spectroscopy (LITR-XAS). Moreover, femtosecond X-ray sources have begun making significant contributions in monitoring coherent molecular motions. This review summarizes recent developments in the field, including technical and scientific challenges as well as several examples involving excited state molecular structure and electronic configuration determinations. Future applications of this technique with high time resolution will enable visualization of fundamental chemical events in many systems and further our understanding in photochemistry.
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  • 2
    Electronic Resource
    Electronic Resource
    Bingley : Emerald
    Internet research 15 (2005), S. 421-446 
    ISSN: 1066-2243
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Computer Science
    Notes: Purpose - This study aims to present a new web page recommendation system that can help users to reduce navigational time on the internet. Design/methodology/approach - The proposed design is based on the primacy effect of browsing behavior, that users prefer top ranking items in search results. This approach is intuitive and requires no training data at all. Findings - A user study showed that users are more satisfied with the proposed search methods than with general search engines using hot keywords. Moreover, two performance measures confirmed that the proposed search methods out-perform other metasearch and search engines. Research limitations/implications - The research has limitations and future work is planned along several directions. First, the search methods implemented are primarily based on the keyword match between the contents of web pages and the user query items. Using the semantic web to recommend concepts and items relevant to the user query might be very helpful in finding the exact contents that users want, particularly when the users do not have enough knowledge about the domains in which they are searching. Second, offering a mechanism that groups search results to improve the way search results are segmented and displayed also assists users to locate the contents they need. Finally, more user feedback is needed to fine-tune the search parameters including a and ß to improve the performance. Practical implications - The proposed model can be used to improve the search performance of any search engine. Originality/value - First, compared with the democratic voting procedure used by metasearch engines, search engine vector voting (SVV) enables a specific combination of search parameters, denoted as a and ß, to be applied to a voted search engine, so that users can either narrow or expand their search results to meet their search preferences. Second, unlike page quality analysis, the hyperlink prediction (HLP) determines qualified pages by simply measuring their user behavior function (UBF) values, and thus takes less computing power. Finally, the advantages of HLP over statistical analysis are that it does not need training data, and it can target both multi-site and site-specific analysis.
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  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Molecular approaches to understanding the functional circuitry of the nervous system promise new insights into the relationship between genes, brain and behaviour. The cellular diversity of the brain necessitates a cellular resolution approach towards understanding the functional genomics of the ...
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 475-479 (Jan. 2005), p. 3783-3786 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: GaN films are grown on Si(111) with low-temperature GaN (LT-GaN) layers as buffer layers by hydride vapor phase epitaxy (HVPE). The LT-GaN layers are deposited at different temperatures ranging from 400 to 900 °C. The surface property, the structure and optical properties of the GaN films with different LT-GaN layers are studied. When deposition temperature of LT-GaN layer is 600 °C, the GaN film shows the best properties
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 364-366 (Dec. 2007), p. 1133-1137 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A new method of etching micro-grating structures (MGSs) on the surface of glazedstainless-steel directly is reported, which makes good use of the interference of nanosecond laserpulses. Through changing the experimental parameters such as working current of the laser andsource beam diameter, the influences of these parameters on the depth of grooves and duty cycle ofMGSs are analyzed. The results measured with conventional optical microscopy and atomic forcemicroscopy (AFM) show that the depth of grooves of MGSs varies from 0 nm to 350 nm, the dutycycle of MGSs changes between 0.4 and 0.9, This method can be used to make a stencil-plate fornano-imprinting. It extends the application of nanosecond laser in laser-induced microstructures,and provides a new method for micromachining micro-optical component
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 364-366 (Dec. 2007), p. 1061-1065 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A novel light guide plate (LGP) with sub-micron gratings (SMGs) on its upper surface isproposed to control the illumination angle and its initial structure of LGP is given. The periods ofSMGs are 0.651μm, 0.516μm and 0.433μm for the LED light sources transmit out vertically withthe incidence angle 45º under the total internal reflection condition. The transmission efficienciesvary between 2% and 43% when the depth of grooves of SMGs changes between 0.05 μm and 0.9μm by using rigorous coupled-wave theory (RCWT). The results show that the LGP utilizing thecharacteristics of the SMGs can control the transmission angle and get homogeneous output
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 561-565 (Oct. 2007), p. 111-114 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The precipitation of copper during aging at 650oC within ferrite in high-purityFe-1.03wt%Cu steel was examined by transmission electron microscopy, and the influence ofprecipitation particles on property of experimental steel was investigated. The microstructure andthe corresponding diffraction patterns of different zone axis were analyzed. Nano-scale copper-richclusters with B2-like structure and high density dislocation around precipitate was observed duringeither solution treatment or aging. Nano-scale metastable precipitates and high density around themwere found to play the most important role for increasing steel strength
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  • 8
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The paper simulated and researched the straightening process of heavy rail by finiteelement software of ANSYS/LS-DYNA. The residual stress of the rail head, rail base, rail loin in the7th deformation zone meets the real straightening condition in the straightening simulation. Thecalculation indicates: The residual stress of the rail head, rail base, rail loin in various deformationzones varies significantly like the variation of tensile-compression-tensile. Compared with the on-siterule, the residual stress of rail base decreased155 Mpa, this is in agreement with the values of practice
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 561-565 (Oct. 2007), p. 367-370 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A novel process, of melt infiltration combined with diffusion annealing technique, wasdeveloped to prepare Ti-Al intermetallics at temperature lower than ingot melting point. In thisprocess, a porous Ti preform was firstly fabricated and the Al melt was reheated to temperatureslightly higher than Al melting point to infiltrate the porous Ti preform by capillary forcespontaneously. After long-time high-temperature diffusion annealing, Ti-Al intermetallic compoundcan be finally synthesized from the bulk Tip+melt Al via diffusion. As example, Ti-46Alintermetallics has been fabricated, and the microstructures and the phases of the as-synthesizedintermetallics were characterized by XRD and SEM. The compressive behavior of the as-synthesizedTi-Al at elevated temperatures has been studied and the reaction mechanism involved in the processfinally analyzed
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 330-332 (Feb. 2007), p. 15-18 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: To increase the mechanical properties of PLA used for fracture inner fixation, β-calciummetaphosphate whiskers were prepared by controlled crystallization in the glass. The factorsinfluencing the morphology of the samples, such as component, time and temperature ofcrystallization were discussed. Results showed that the high quality of β-calcium metaphosphatewhiskers can be obtained by crystallization treating for 36 hours and washing for 48 hours at 80℃distilled water. β-calcium metaphosphate whiskers having high aspect ratios of 20-100 withdiameters of 1-5μm were achieved at the optimized conditions
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