Searched for: author:"Liu, D."
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Liu, D. (author), Wang, H. (author), Van Mieghem, P. (author)
In recent years, many network perturbation techniques, such as topological perturbations and service perturbations, were employed to study and improve the robustness of complex networks. However, there is no general way to evaluate the network robustness. In this paper, we propose a global measure for a network, the reconstructability...
journal article 2010
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Van Mieghem, P. (author), Stevanovi?, D. (author), Kuipers, F. (author), Li, C. (author), Van de Bovenkamp, R. (author), Liu, D. (author), Wang, H. (author)
The decrease of the spectral radius, an important characterizer of network dynamics, by removing links is investigated. The minimization of the spectral radius by removing m links is shown to be an NP-complete problem, which suggests considering heuristic strategies. Several greedy strategies are compared, and several bounds on the decrease of...
journal article 2011
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Liu, D. (author), Blenn, N. (author), Van Mieghem, P.F.A. (author)
ur society contains all types of organizations, such as companies, research groups and hobby clubs. Affliation networks, as a large and important portion of social networks, consist of individuals and their affiation relations: Two individuals are connected by a link if they belong to the same organization(s). Affliation networks naturally...
journal article 2012
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Liu, D. (author), Blenn, N. (author), Van Mieghem, P.F.A. (author)
Social networks, as well as many other real-world networks, exhibit overlapping community structure. In this paper, we present formulas which facilitate the computation for characterizing the overlapping community structure of networks. A hypergraph representation of networks with overlapping community structure is introduced. Using the...
journal article 2012
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Liu, D. (author), Trajanovski, S. (author), Van Mieghem, P. (author)
For a fixed number N of nodes, the number of links L in the line graph H(N,L) can only appear in consecutive intervals, called a band of L. We prove that some consecutive integers can never represent the number of links L in H(N,L), and they are called a bandgap of L. We give the exact expressions of bands and bandgaps of L. We propose a model...
journal article 2013
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Liu, D. (author)
The infrastructure networks, including the Internet, telecommunication networks, electrical power grids, transportation networks (road, railway, waterway, and airway networks), gas networks and water networks, are becoming more and more complex. The complex infrastructure networks are crucial to our human society, and it has been a hot research ...
doctoral thesis 2013
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Kostopoulos, D. (author), Liu, D. (author), Genani, G. (author), Polinder, H. (author)
Offshore wind is considered a vital component of the future large scale renewable generation portfolio. Intense R&D effort is occurring in both the technology and the supply chain aiming at cost reduction. The drivetrain of wind turbines is an area of continuous evolution with currently no one standard configuration in the industry. It is...
conference paper 2013
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Abrahamsen, A.B. (author), Magnusson, N. (author), Jensen, B.B. (author), Liu, D. (author), Polinder, H. (author)
An MgB2 race track coil intended for demonstrating a down scaled pole of a 10 MW direct drive wind turbine generator has been designed. The coil consists of 10 double pancake coils stacked into a race track coil with a cross section of 84 mm x 80 mm. The length of the straight section is 0.5 m and the diameter of the end sections is 0.3 m....
conference paper 2014
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Abrahamsen, A.B. (author), Magnusson, N. (author), Liu, D. (author), Stehouwer, E. (author), Hendriks, B. (author), Polinder, H. (author)
A superconducting direct drive generator based on field windings of MgB2 superconducting tape is proposed as a solution by mounting the generator in front of the blades using a king-pin nacelle design for offshore turbines with power ratings larger than 10 MW as investigated in the INNWIND.EU project.
conference paper 2014
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Liu, D. (author), Trajanovski, S. (author), Van Mieghem, P. (author)
This paper presents a new and efficient algorithm, ILIGRA, for inverse line graph construction. Given a line graph H, ILIGRA constructs its root graph G with the time complexity being linear in the number of nodes in H. If ILIGRA does not know whether the given graph H is a line graph, it firstly assumes that H is a line graph and starts its...
journal article 2014
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Liu, D. (author), Heard, P. (author), Savija, B. (author), Smith, G. (author), Schlangen, E. (author), Flewitt, P. (author)
In the present work, the microstructure and mechanical properties of Gilsocarbon graphite have been characterized over a range of length-scales. Optical imaging, combined with 3D X-ray computed tomography and 3D high-resolution tomography based on focus ion beam milling has been adopted for microstructural characterization. A range of small...
conference paper 2015
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Heard, P (author), Šavija, B. (author), Liu, D (author), Smith, GE (author), Hallam, KR (author), Schlangen, H.E.J.G. (author), Flewitt, P.E.J. (author)
In quasibrittle materials the addition of specific microstructural features such as porosity can lead to departure from linear elastic behaviour prior to maximum force, followed by graceful failure. A simple but extreme example is reticulated vitreous carbon foam, with its opencell structure of brittle ligaments connected in a threedimensional...
conference paper 2016
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Song, X. (author), Polinder, H. (author), Liu, D. (author), Mijatovic, Nenad (author), Holbøll, Joachim (author), Jensen, Bogi Bech (author)
Direct drive high temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits happen at generator terminals. In this paper, a finite...
conference paper 2016
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Wang, X. (author), Liu, D. (author), Lahaye, D.J.P. (author), Polinder, H. (author), Ferreira, J.A. (author)
Permanent-magnet machines with fractional slot concentrated windings are easy to manufacture. Their popularity therefore is steadily increasing. Without a proper design, however, the induced eddy-current losses in the solid rotor get rather high. The modeling and the prediction of eddy-current losses for these machines are thus very important...
conference paper 2016
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Liu, D (author), Šavija, B. (author), Smith, G.E. (author), Flewitt, P.E.J. (author), Lowe, T. (author), Schlangen, H.E.J.G. (author)
In this work, porosity-property relationships of quasi-brittle materials are explored through a combined experimental and numerical approach. In the experimental part, hemihyrate gypsum plaster powder (CaSO 4 ⋅1/2H 2 O CaSO4⋅1/2H2O) and expanded spherical polystyrene beads (1.5–2.0 mm dia.) have been mixed to form a model material with...
journal article 2017
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Song, X. (author), Liu, D. (author), Polinder, H. (author), Mijatovic, Nenad (author), Holbøll, Joachim (author), Jensen, Bogi Bech (author)
Direct drive high temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits happen at generator terminals. In this paper, a finite...
journal article 2017
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Wang, X. (author), Liu, D. (author), Lahaye, D.J.P. (author), Polinder, H. (author), Ferreira, J.A. (author)
The brushless doubly-fed induction machine (DFIM) has great potential as a variable-speed generator for wind turbine applications. This special machine has a richer space-harmonic spectrum due to its special nested-loop rotor construction compared with conventional induction machines. It may result in higher iron losses, higher torque ripple and...
conference paper 2017
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Liu, D. (author), Kenjeres, S. (author)
In the present study, we address the development and application of an efficient tool for conversion of results obtained by an integrated computational fluid dynamics (CFD) and computational reaction dynamics (CRD) approach and their visualization in the Google Earth. We focus on results typical for environmental fluid mechanics studies at a...
journal article 2017
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Abrahamsen, Asger Bech (author), Liu, D. (author), Magnusson, Niklas (author), Thomas, A (author), Z., Azar (author), Stehouwer, Ewoud (author), Hendriks, E (author), Penzkofer, A. (author), Atallah, K (author), Dragan, R.R. (author), .Clark, R.E. (author), Deng, F. (author), Chen, Z (author), Karwatzki, D. (author), Mertens, A. (author), Parker, M. (author), Finney, SJ (author), Polinder, H. (author)
Innovative drive trains targeted at 10-20 MW offshore turbines are investigated in the INNWIND.EU project in order to determine the impact on the Levelized Cost of Energy (LCoE) resulting when installed in the ,North sea at 50 m of water [1]. The two main technologies studied are superconducting direct drive (SCDD)[2] and the magnetic pseudo...
abstract 2017
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Liu, D. (author), Polinder, H. (author), Abrahamsen, Asger B. (author), Ferreira, J.A. (author)
This paper aims at assessing the potential of partially superconducting generators for 10 MW direct-drive wind turbines by investigating their performance for a very wide range of excitation currents. Performance indicators such as shear stress and efficiency and other generator characteristics are compared for 12 different generator topologies....
journal article 2017
Searched for: author:"Liu, D."
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