1,724,021 research outputs found
Small-Scale Properties of Two-Dimensional Rayleigh-Taylor Turbulence
No full textWe report a high-resolution numerical study of small-scale properties of two-dimensional (2D) miscible Rayleigh-Taylor (RT) incompressible turbulence with the Boussinesq approximation at small Atwood number and unit Prandtl number. Our results show that the buoyancy force balances the inertial force at all scales below the integral length scale and thus validate the basic force-balance assumption of the Bolgiano-Obukhov scenario in 2D RT turbulence. We further examine other small-scale properties of 2D RT turbulence, such as temporal evolution of energy and thermal dissipation rates, the emergence of intermittency and anomalous scaling for high order moments of velocity and temperature differences, distributions of local dissipation scales, and so on
A numerical method for the calculation of dynamic response and acoustic radiation from an underwater structure
No full textAn approach combining finite element with boundary element methods is proposed to calculate the elastic vibration and acoustic field radiated from an underwater structure. The FEM software NASTRAN is employed for computation of the structural vibration. An uncoupled boundary element method, based on the potential decomposition technique, is described to determine the acoustic added mass and damping coefficients that result due to fluid loading effects. The acoustic matrices of added mass and damping coefficients are then added to the structural mass and damping matrices, respectively, by the DMAP modules of NASTRAN. Numerical results are shown to be in good agreement with experimental data. The complex eigenvalue analyses of underwater structure are obtained by NASTRAN solution sequence SOL107. Results obtained from this study suggest that the natural frequencies of underwater structures are only weakly dependent on the acoustic frequency if the acoustic wavelength is roughly twice as large as the maximum structural dimension
A new method of determining acoustic added mass and damping coefficient of fluid-structure interaction
No full textThe Princess in the Castle: Challenging Serious Game Play for Integrated Policy Analysis and Planning
No full textWhat are the principles that make societal problems socio-technically complex? And, even more important, how can we support public policymaking in the wake of socio-technical complexity? In The Princess in the Castle, the author investigates if, why and how serious games and game-like simulations (SGs) can support integrated policy making and planning, especially in relation to managing rivers and oceans. She argues that ‘playful methods’ are particularly suited to surround sophisticated analysis with extensive participation. The book contains many examples and illustrations but centres on: the Climate Game, used in a neighbourhood reconstruction project incorporating climate adaptation measures; The Blokkendoos Planning Kit, used in the Netherlands’ planning project Room for the River for integrated flood management; the MSP Challenge, used to further the development of integrated, eco-system based marine spatial planning. The book provides a de- and re-construction of the ‘principles of play’ that underlying integrated policy analysis. The perceived usefulness of game-like tools in the Dutch and Chinese policy contexts is empirically studied. The author concludes that serious games for policy-making and planning are powerful methods with largely untapped potential. Yet, without room to play they can be easily turn into ineffective and expensive toys. Qiqi Zhou is a researcher at Delft University of Technology, the Netherlands. She is involved in several research projects with Dutch and Chinese universities.Policy, Organization, Law and Gaming (POLG)Technology, Policy and Managemen
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The Integration of IVUS and OCT
No full textUltrasound and optical coherence tomography (OCT) provide complementary capabilities-ultrasound has high penetration depth but low resolution; OCT has high resolution but low penetration depth. The integration of these two technologies enable superior imaging capabilities for intravascular applications.Jiawen Li, Teng Ma, Qifa Zhou and Zhongping Che
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