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  • 1
    Publication Date: 2011-05-20
    Description: In this work, hexagonal solid solutions of (Gd 0.95 Eu 0.05 )(OH) 3 with two distinctive morphologies of nanorods and nanotubes were successfully synthesized via hydrothermal treatment of mixed nitrate solutions in the presence of ammonium hydroxide. The hydroxide samples exhibited characteristic Eu 3+ photoluminescence through the energy transfer from Gd 3+ to Eu 3+ and the self-excitation of Eu 3+ . The hydroxide precursors transformed into cubic (Gd 0.95 Eu 0.05 ) 2 O 3 at ~500 °C via an intermediate monoclinic (Gd 0.95 Eu 0.05 )OOH phase, and the Eu 3+ coordination accordingly experienced symmetry changes from D 3 h to C 2 v , and then to C 2 / S 6 . The cubic (Gd 0.95 Eu 0.05 ) 2 O 3 well retained the original morphologies of their p...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 2
    Publication Date: 2017-11-30
    Description: In this paper, the curing kinetics of 4,4′-Methylenebis epoxy resin(TGDDM) and m-Xylylenediamine(m-XDA) was investigated by non-isothermal differential scanning calorimetry(DSC) at various heating rates. Selected non-isothermal methods for analyzing curing kinetics were compared. The activation energy(E) and the correlation coefficient(R) were obtained by different isoconversional methods. The reaction order(n) was obtained by the activation energy in different isoconversional methods for the by Crane equation. The results show that the apparent activation energy are 65.23kJ/mol, 52.20 kJ/mol and 66.10 kJ/mol by using the method of Kissinger, Friedman and F-W-O, the reaction order are 0.911, 0.729 and 0.923 by using the method of Kissinger, Friedman and F-W-O.
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 3
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    Il Cigno Galileo Galilei
    In:  Professional Paper, Open-File Rept., Earthquake Prediction, Roma, Il Cigno Galileo Galilei, vol. 1, no. 2, pp. 317-332, (ISBN 0080419208)
    Publication Date: 1992
    Keywords: Earthquake precursor: prediction research ; Earthquake precursor: deformation or strain ; Earth tides ; Earthquake precursor: tilt ; JZSCHAU
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 37 (1994), S. 3585-3603 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In the paper we present a postprocessed type of a posteriori error estimate and a h-version adaptive procedure for the semidiscrete finite element method in dynamic analysis. In space the super-convergent patch recovery technique is used for determining higher-order accurate stresses and, thus, a spatial error estimate. In time a postprocessing technique is developed for obtaining a local error estimate for one step time integration schemes (the HHT-α method). Coupling the error estimate with a mesh generator, a h-version adaptive finite element procedure is presented for two-dimensional dynamic analysis. It updates the spatial mesh and time step automatically so that the discretization errors are controlled within specified tolerances. Numerical studies on different problems are presented for demonstrating the performances of the proposed adaptive procedure.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 2131-2152 
    ISSN: 0029-5981
    Keywords: discontinuous Galerkin finite element method ; predictor-multicorrector ; adaptive time integration ; structural dynamics ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper studies a time-discontinuous Galerkin finite element method for structural dynamic problems, by which both displacements and velocities are approximated as piecewise linear functions in the time domain and may be discontinuous at the discrete time levels. A new iterative solution algorithm which involves only one factorization for each fixed time step size and a few iterations at each step is presented for solving the resulted system of coupled equations. By using the jumps of the displacements and the velocities in the total energy norm as error indicators, an adaptive time-stepping procedure for selecting the proper time step size is described. Numerical examples including both single-DOF and multi-DOF problems are used to illustrate the performance of these algorithms. Comparisons with the exact results and/or the results by the Newmark integration scheme are given. It is shown that the time-discontinuous Galerkin finite element method discussed in this study possesses good accuracy (third order) and stability properties, its numerical implementation is not difficult, and the higher computational cost needed in each time step is compensated by use of a larger time step size.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 9 (1993), S. 273-292 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A simple a posteriori local error estimator for time discretization in structural dynamic analysis is presented. It is derived from the difference of the solutions between an ordinary integration method (the Newmark scheme) and another higher-order one which assumes that the derivatives of accelerations vary linearly within each time step. It may be obtained directly without resolving new equations, so the additional computational cost is small and the implementation is convenient. Furthermore, it is shown that this error estimator may also be obtained by Taylor expansion or by a post-processing technique. Accordingly, an adaptive time-stepping procedure, which automatically adjusts the time-step size so that the local error at each time step is within a prescribed accuracy, is described. Numerical examples, including two single-DOF problems, a two-DOF problem and a multi-DOF model, are presented. The results show that the presented local error estimator is simple, reliable and accurate.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 10 (1994), S. 313-320 
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In the paper we present a superconvergent patch recovery technique for obtaining higher-order-accurate finite-element solutions and thus a postprocessed type of L2 norm error estimate. Two modifications make our procedure different from the one proposed by Zienkiewicz and Zhu (1992), in which higher-order-accurate derivatives of the finite-element solution at nodes are determined. Firstly, the recovery process is made for element, not for nodes. An ‘element patch’, which represents the union of an element under consideration and the surrounding elements, is introduced. Secondly, the local error estimate is calculated directly from the improved solution for this element. Numerical tests on both 1D and 2D model problems show that this method can provide an asymptotically exact a posteriori L2 norm error estimate if the used element possesses superconvergent points for the solutions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 2017-06-10
    Description: This paper mainly researched the hydrothermal synthesis of Natrolite, using amorphous silicon source from the purified attapulgite. The effects of silicon source, silicon aluminum ratio, crystallization time and crystallization temperature on the synthesis of natrolite were investigated. The results showed that the optimal synthesis condition of natrolite was: Hydrothermal activated ATP with NaOH was silicon source, silicon aluminum ratio was 10:1, crystallization time lasted to 72h and crystallization temperature was 150°C, the template was removed by calcining 8 hours at 550°C. The structural formula of obtained natrolite is Na 2 Al 2 Si 3 O 10 •2H 2 O.
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 9
    Publication Date: 2017-02-14
    Description: Vermifiltration system has been reported to enhance sludge degradation and relieve the potential risks of heavy metals, whereas few studies focus on the seasonal variability of heavy metal content and its chemical speciation in excess sludge by vermi-stabilization. The results of this study showed that total contents of Zn, Pb, Cr and the treatment efficiency of vermifilter were higher in summer and lower in winter due to the temperature effect. While Cu was observed to not be dependent on season. Further investigation using a five-step fractionation procedure to evaluate the main chemical speciations of metals in the sludge showed that there were similar variations in the five fractions (F1-F5) between each season, which indicated that the chemical speciation of heavy metals were most affected by vermifiltration technique than seasonal factor. The transformations among the five fractions suggested that the vermifiltration significantly reduced the mobility and bioavailability o...
    Print ISSN: 1755-1307
    Electronic ISSN: 1755-1315
    Topics: Geography , Geosciences , Physics
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  • 10
    Publication Date: 2018-10-02
    Description: Sleep plays a significant role in human health. Along with the emergency of diseases related to sleep, sleep monitoring is becoming a hotspot. Traditionally, Polysomnography (PSG) is considered as the gold standard for sleep monitoring, but it is expensive, time-consuming, and uncomfortable, especially not ideal for long-term sleep studies. Thus, exploring alternative sleep monitoring method has drawn much attention of researchers. Currently most of the sleep monitoring methods require complicated signals and feature extraction process. However, this paper innovatively proposes a method using simple signal of heart rate and respiration rate, and integrating the prior knowledge of experts to simplify the feature extraction process, which can make the subsequent classifier distinguish wake state and sleep state easily. In this paper, we used multi-layer neural network as a classifier, getting a Cohen’s kappa value of 0.739, and the overall accuracy of classifying sleep and wake st...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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