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  • 1
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    Optimal localization of diffusion sources in complex networks (2017)
    Royal Society
    Details
    Publication Date: 2017-04-13
    Description: Locating sources of diffusion and spreading from minimum data is a significant problem in network science with great applied values to the society. However, a general theoretical framework dealing with optimal source localization is lacking. Combining the controllability theory for complex networks and compressive sensing, we develop a framework with high efficiency and robustness for optimal source localization in arbitrary weighted networks with arbitrary distribution of sources. We offer a minimum output analysis to quantify the source locatability through a minimal number of messenger nodes that produce sufficient measurement for fully locating the sources. When the minimum messenger nodes are discerned, the problem of optimal source localization becomes one of sparse signal reconstruction, which can be solved using compressive sensing. Application of our framework to model and empirical networks demonstrates that sources in homogeneous and denser networks are more readily to be located. A surprising finding is that, for a connected undirected network with random link weights and weak noise, a single messenger node is sufficient for locating any number of sources. The framework deepens our understanding of the network source localization problem and offers efficient tools with broad applications.
    Keywords: complexity, graph theory
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 2
    Electronic Resource
    Electronic Resource
    Vertical stress distribution due to an arbitrarily shaped foundation using triangulation and an analytical expression for a triangular loaded region (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 15 (1991), S. 51-60 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Using the basic Boussinesq's equation, the expression for the vertical stress distribution (σz) underneath any point on the ground surface due to a general triangular loaded region in a preferred orientation with a linearly varied loading has been successfully derived. When the triangle is not in a preferred orientation, a simple axis transformation is required and the expression will be equally applicable. Based on this expression, σz due to an arbitrarily shaped loaded foundation can simply be determined by first triangulating the loaded area and summing up the contributions from each generated triangular region. The procedures for triangulating and calculating the stress distribution can be simply automated through computer programs.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610150105
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A numerical model for wave scattering problems in infinite media due to p- and sv-wave incidences (1992)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 33 (1992), S. 1661-1682 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Based on elastic wave motion theory and the superposition concept, a numerical model for wave scattering problems in infinite media due to P-wave and SV-wave incidences is presented in this paper. Since this model is based on a coupled system of finite and infinite elements for simulating wave propagation in infinite media, the complexity of geometry and the variability of material properties in the foundation can be realistically simulated. Through a systematic study of the characteristics of a plane harmonic P-wave and SV-wave incidences on a fixed boundary, the concept of stress increase factors and stress factors which can be used to calculate the generalized stresses on the wave input boundary due to the SV-wave and P-wave incidences is also proposed. The effects of incident wave mode, incident angle and Poisson's ratio in the foundation on the stress increase factors and the stress factors have been studied in detail. Finally, the proposed model has been applied to a half-plane foundation and a semi-circular canyon to calculate SV-wave and P-wave scattering problems. The numerical results obtained show good agreement with the theoretical results and Wong's analytical results.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620330808
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Discussion on: Vertical stress distribution due to an arbitrarily shaped foundation using triangulation and an analytical expression for a triangular loaded region (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 16 (1992), S. 377-381 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610160506
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  • 5
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    Compressor map regression modelling based on partial least squares (2018)
    Royal Society
    Details
    Publication Date: 2018-08-30
    Description: In this work, two kinds of partial least squares modelling methods are applied to predict a compressor map: one uses a power function polynomial as the basis function (PLSO), and the other uses a trigonometric function polynomial (PLSN). To demonstrate the potential capabilities of PLSO and PLSN for a typical interpolated prediction and an extrapolated prediction, they are compared with two other classical data-driven modelling methods, namely the look-up table and artificial neural network (ANN). PLSO and PLSN are also compared with each other. The results show that PLSO and PLSN have a better prediction performance than the look-up table and the ANN, especially for the extrapolated prediction. The computational time is also decreased sharply. Compared with PLSO, PLSN is characterized by a higher prediction accuracy and shorter computational time than PLSO. It is expected that PLSN could save computational time and also improve the accuracy of a thermodynamic model of a diesel engine.
    Keywords: mathematical modelling, mechanical engineering, power and energy systems
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 6
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    Optimized modelling and application of exhaust gas recirculation performance evaluation of turbocharged diesel engine (2018)
    Royal Society
    Details
    Publication Date: 2018-06-28
    Description: Aimed at the problem of exhaust gas recirculation (EGR) performance evaluation and optimal EGR rate determination of turbocharged diesel engines, an optimized decision-making method, based on grey theory and entropy weight, was proposed. The internal combustion pressure, fuel consumption rate, NO X , CO and smoke were selected as the decision-making targets and the initial decision-making model was established based on the traditional grey decision-making theory. According to the characteristics and optimization requirements of EGR, the optimal compromise between combustion and emission performance is proposed to transform into decision-making target weighting problem, then an optimized subjective weighting method based on expert scoring and grey relational analysis is proposed. Finally, the entropy weight method was used to solve the objective weight and the optimized multi-objective grey decision-making model was established, which can not only weaken the human error of subjective empowerment, but also fully explore the intrinsic relationship of the evaluation indexes. At last, an optimization simulation platform for EGR performance evaluation based on MATLB/GUIDE was designed and established. The results show that the optimization simulation platform can effectively improve the efficiency of simulation calculation, which is more convenient for practical engineering applications. The optimized method can successfully realize EGR performance evaluation and optimal EGR rate determination under different working conditions. The decision-making result was consistent with the present EGR control strategies, which provide a new research idea for EGR performance optimization.
    Keywords: mechanical engineering, energy, applied mathematics
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 7
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    A prediction model of compressor with variable-geometry diffuser based on elliptic equation and partial least squares (2018)
    Royal Society
    Details
    Publication Date: 2018-01-25
    Description: To achieve a much more extensive intake air flow range of the diesel engine, a variable-geometry compressor (VGC) is introduced into a turbocharged diesel engine. However, due to the variable diffuser vane angle (DVA), the prediction for the performance of the VGC becomes more difficult than for a normal compressor. In the present study, a prediction model comprising an elliptical equation and a PLS (partial least-squares) model was proposed to predict the performance of the VGC. The speed lines of the pressure ratio map and the efficiency map were fitted with the elliptical equation, and the coefficients of the elliptical equation were introduced into the PLS model to build the polynomial relationship between the coefficients and the relative speed, the DVA. Further, the maximal order of the polynomial was investigated in detail to reduce the number of sub-coefficients and achieve acceptable fit accuracy simultaneously. The prediction model was validated with sample data and in order to present the superiority of compressor performance prediction, the prediction results of this model were compared with those of the look-up table and back-propagation neural networks (BPNNs). The validation and comparison results show that the prediction accuracy of the new developed model is acceptable, and this model is much more suitable than the look-up table and the BPNN methods under the same condition in VGC performance prediction. Moreover, the new developed prediction model provides a novel and effective prediction solution for the VGC and can be used to improve the accuracy of the thermodynamic model for turbocharged diesel engines in the future.
    Keywords: mathematical modelling, mechanical engineering
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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