| 1. |
- Aaboen, Lise, 1978, et al.
(författare)
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Incubator performance : An efficiency frontier analysis
- 2008
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Ingår i: International Journal of Business Innovation and Research. - 1751-0252 .- 1751-0260. ; 2:4, s. 354-380
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Tidskriftsartikel (refereegranskat)abstract
- Assessments and evaluations of incubators has been a topic of discussion for as long as incubators have been in existence due to the fact that there has not been an agreement on how to determine good performance. This paper demonstrates the use of Data Envelopment Analysis (DEA) when studying performance of incubators. More specifically, it does so within the four dimensions of cooperation with universities, business networks, external funding and competence development on a sample of 16 Swedish incubators. We show that DEA enables us to measure non-numerical dimensions, and to simultaneously take into account the efforts made by both the incubator and the outcomes. Moreover, DEA provides benchmarks and, based on a model that divides the incubators into four different groups, illustrates the difference between the benchmark and the incubators' current situation.
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| 2. |
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| 3. |
- Ahmet, Zeynep, et al.
(författare)
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Supporting embodied exploration of physical concepts in mixed digital and physical interactive settings
- 2011
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Ingår i: TEI'11. - Funchal, Portugal : ACM Press. - 1450304788 ; , s. 109-116
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Konferensbidrag (refereegranskat)abstract
- In this paper findings are presented from a study on how sensor equipped computer game technologies can be used to create tools for educational settings to learn about for example concepts in physics. In a workshop focusing on the concept of gravity, a group of children interacted with an environment consisting of both physical and digital interactive components. We discuss how the mixed digital and physical setting affects the children's coordination and collaboration and their strategies to solve the given assignment. Findings suggest that the embodied nature of the technology create new opportunities for collaboration and that the alignment of the physical and digital parts of the interactive setting is important in order to create a seamless experience that takes advantage of the properties of the respective media.
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| 4. |
- Albernaz, Daniel L., et al.
(författare)
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Droplet deformation and heat transfer in isotropic turbulence
- 2017
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Ingår i: Journal of Fluid Mechanics. - : Cambridge University Press. - 0022-1120 .- 1469-7645. ; 820, s. 61-85
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Tidskriftsartikel (refereegranskat)abstract
- The heat and mass transfer of deformable droplets in turbulent flows is crucial. to a wide range of applications, such as cloud dynamics and internal combustion engines. This study investigates a single droplet undergoing phase change in isotropic turbulence using numerical simulations with a hybrid lattice Boltzmann scheme. Phase separation is controlled by a non-ideal equation of state and density contrast is taken into consideration. Droplet deformation is caused by pressure and shear stress at the droplet interface. The statistics of thermodynamic variables are quantified and averaged over both the liquid and vapour phases. The occurrence of evaporation and condensation is correlated to temperature fluctuations, surface tension variation and turbulence intensity. The temporal spectra of droplet deformations are analysed and related to the droplet surface area. Different modes of oscillation are clearly identified from the deformation power spectrum for low Taylor Reynolds number Re, whereas nonlinearities are produced with the increase of Re A, as intermediate frequencies are seen to overlap. As an outcome, a continuous spectrum is observed, which shows a decrease in the power spectrum that scales as similar to f(-3) Correlations between the droplet Weber number, deformation parameter, fluctuations of the droplet volume and thermodynamic variables are also developed.
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| 5. |
- Albernaz, Daniel L., 1984-, et al.
(författare)
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Lattice Boltzmann Method for the evaporation of a suspended droplet
- 2013
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Ingår i: Interfacial phenomena and heat transfer. - : Begell House. - 2167-857X. ; 1, s. 245-258
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we consider a thermal multiphase lattice Boltzmann method (LBM) to investigate the heating and vaporization of a suspended droplet. An important benefit from the LBM is that phase separation is generated spontaneously and jump conditions for heat and mass transfer are not imposed. We use double distribution functions in order to solve for momentum and energy equations. The force is incorporated via the exact difference method (EDM) scheme where different equations of state (EOS) are used, including the Peng-Robinson EOS. The equilibrium and boundary conditions are carefully studied. Results are presented for a hexane droplet set to evaporate in a superheated gas, for static condition and under gravitational effects. For the static droplet, the numerical simulations show that capillary pressure and the cooling effect at the interface play a major role. When the droplet is convected due to the gravitational field, the relative motion between the droplet and surrounding gas enhances the heat transfer. Evolution of density and temperature fields are illustrated in details.
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| 6. |
- Albernaz, Daniel L., 1984-, et al.
(författare)
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Simulation of a suspended droplet under evaporation with Marangoni effects
- 2016
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier. - 0017-9310 .- 1879-2189. ; 91, s. 853-860
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the Marangoni effects in a hexane droplet under evaporation and close to its critical point. A lattice Boltzmann model is used to perform 3D numerical simulations. In a first case, the droplet is placed in its own vapor and a temperature gradient is imposed. The droplet locomotion through the domain is observed, where the temperature differences across the surface is proportional to the droplet velocity and the Marangoni effect is confirmed. The droplet is then set under a forced convection condition. The results show that the Marangoni stresses play a major role in maintaining the internal circulation when the superheated vapor temperature is increased. Surprisingly, surface tension variations along the interface due to temperature change may affect heat transfer and internal circulation even for low Weber number. Other results and considerations regarding the droplet surface are also discussed.
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| 7. |
- Albernaz, Daniel, et al.
(författare)
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Multirelaxation-time lattice Boltzmann model for droplet heating and evaporation under forced convection
- 2015
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1539-3755 .- 1550-2376. ; 91:4
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the evaporation of a droplet surrounded by superheated vapor with relative motion between phases. The evaporating droplet is a challenging process, as one must take into account the transport of mass, momentum, and heat. Here a lattice Boltzmann method is employed where phase change is controlled by a nonideal equation of state. First, numerical simulations are compared to the D-2 law for a vaporizing static droplet and good agreement is observed. Results are then presented for a droplet in a Lagrangian frame under a superheated vapor flow. Evaporation is described in terms of the temperature difference between liquid-vapor and the inertial forces. The internal liquid circulation driven by surface-shear stresses due to convection enhances the evaporation rate. Numerical simulations demonstrate that for higher Reynolds numbers, the dynamics of vaporization flux can be significantly affected, which may cause an oscillatory behavior on the droplet evaporation. The droplet-wake interaction and local mass flux are discussed in detail.
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| 8. |
- Amberg, Gustav
(författare)
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Detailed modelling of contact line motion in oscillatory wetting
- 2022
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Ingår i: NPJ MICROGRAVITY. - : Springer Nature. - 2373-8065. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- The experimental results of Xia and Steen for the contact line dynamics of a drop placed on a vertically oscillating surface are analyzed by numerical phase field simulations. The concept of contact line mobility or friction is discussed, and an angle-dependent model is formulated. The results of numerical simulations based on this model are compared to the detailed experimental results of Xia and Steen with good general agreement. The total energy input in terms of work done by the oscillating support, and the dissipation at the contact line, are calculated from the simulated results. It is found that the contact line dissipation is almost entirely responsible for the dissipation that sets the amplitude of the response. It is argued that angle-dependent line friction may be a fruitful interpretation of the relations between contact line speed and dynamic contact angle that are often used in practical computational fluid dynamics.
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| 9. |
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| 10. |
- Andersson Schwarz, Jonas, 1978-
(författare)
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De digitala vidderna styrs från ovan
- 2014
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Ingår i: Svenska Dagbladet. - Stockholm. - 1101-2412. ; :23 jun
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Tidskriftsartikel (populärvet., debatt m.m.)
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