| 1. |
|
|
| 2. |
- Tuovinen, Heimo, et al.
(författare)
-
Sensitivity calculations of tunnel fires using CFD
- 1996
-
Ingår i: Fire Technology. - 0015-2684. ; 32:2, s. 99-119
-
Tidskriftsartikel (refereegranskat)abstract
- Detailed numerical simulations of fires in road tunnels were carried out using the CFD code JASMINE. Fire tests performed in the Ofenegg tunnel have also been validated. A parametric study of fires in an arbitrary 300-m-long tunnel was made, in which the influence of fire size, tunnel width, ventilation and ground slope was investigated. The movement of hazardous temperature and smoke regions as a function of time was calculated to investigate escape possibilities from the tunnel in case of fire.
|
|
| 3. |
- Locateli, C.C., et al.
(författare)
-
Digital hydraulic system using pumps and on/off valves controlling the actuator
- 2014
-
Ingår i: PROCEEDINGS OF THE FPNI PH.D SYMPOSIUM ON FLUID POWER. - : ASME Press. - 9780791845820
-
Konferensbidrag (refereegranskat)abstract
- Hydraulic systems employed in several industrial and mobile applications present significant advantages, such as a high power-to-weight ratio and fast dynamic response. However, these systems have low efficiency due to high power dissipation. A recent concept called digital hydraulics comprises particularities that create opportunities for a reduction in load loss. This paper proposes a configuration and control method for actuator speed control based on the principles of digital hydraulics. In this context, several fixed displacement units and on/off valves are connected directly to the actuators without throttling valves. The system studied here presents three operation methods (pump mode, motor mode and idle mode), which allows discrete valves to replace continuous or flow control valves in order to control the actuator. Furthermore, a fixed or variable displacement pump with large displacement is replaced by several small, fixed displacement units. Simulations are performed with a co-simulation technique using AMESim and MATLAB. The actuator speed, inlet and outlet pressures on the fixed displacement units and flow rate in the circuit lines are analysed. Preliminary simulation results exhibit smooth transitions between speed levels, adequate dynamic performance, low power dissipation and high energy-storage capacity. A specific limitation of this technology is the obtained actuator discrete speed. The main contributions of this research are the development of a digital hydraulic system configuration and its control strategy, which allows speed control of hydraulic actuators and provides the capacity to store energy.
|
|
| 4. |
- Kanngiesser, Franz, 1992, et al.
(författare)
-
Calculation of optical properties of light-absorbing carbon with weakly absorbing coating: A model with tunable transition from film-coating to spherical-shell coating
- 2018
-
Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier BV. - 0022-4073. ; 216, s. 17-36
-
Tidskriftsartikel (refereegranskat)abstract
- Optical properties of particles consisting of light-absorbing carbon (or soot) and a weakly absorbing coating material are computed at a wavelength of 355 nm and 532 nm. A morphological particle model is used, in which small amounts of coating are applied as a thin film to the surface of the aggregate, while heavily coated aggregates are enclosed in a spherical shell. As the amount of coating material is increased, a gradual transition from film-coating to spherical-shell coating is accounted for. The speed of this transition can be varied by specifying a single parameter. Two different choices of this parameter, corresponding to a slow and a rapid transition from film-coating to spherical-shell coating, respectively, are investigated. For low soot volume fractions the impact of this transition on the linear depolarisation ratio δlis most pronounced. The model that describes a rapid transition to a spherical coating yields results for δlthat are more consistent with existing lidar field measurements than the slow-transition model. At 532 nm the relative uncertainty in modelled δlfor a rapid transition values due to uncertainties in the aggregate's geometry and chemical composition are estimated to range from 109 to 243%, depending on the soot volume fraction. At 355 nm the relative uncertainties were estimated to range from 90.9 to 200%.
|
|
| 5. |
- Maro, Salome, 1987, et al.
(författare)
-
Software traceability in the automotive domain: Challenges and solutions
- 2018
-
Ingår i: Journal of Systems and Software. - : Elsevier BV. - 0164-1212. ; 141, s. 85-110
-
Tidskriftsartikel (refereegranskat)abstract
- In the automotive domain, the development of all safety-critical systems has to comply with safety standards such as ISO 26262. These standards require established traceability, the ability to relate artifacts created during development of a system, to ensure resulting systems are well-tested and therefore safe. This paper contrasts general traceability challenges and solutions with those specific to the automotive domain, and investigates how they manifest in practice. We combine three data sources: a tertiary literature review to identify general challenges and solutions; a case study with an automotive supplier as validation for how the challenges and solutions are experienced in practice; and a multi-vocal literature review to identify challenges and solutions specific to the automotive domain. We found 22 challenges and 16 unique solutions in the reviews. 17 challenges were identified in the case study; six remain unsolved. We discuss challenges and solutions from the perspectives of academia, tool vendors, consultants and users, and identify differences between scientific and "grey" literature. We discuss why challenges remain unsolved and propose solutions. Our findings indicate that there is a significant overlap between general traceability challenges and those in the automotive domain but that they are experienced differently. (C) 2018 Elsevier Inc. All rights reserved.
|
|
| 6. |
|
|
| 7. |
- Bentell, J., et al.
(författare)
-
Characterisation of n-InP/n-GaAs Wafer Fused Heterojunctions
- 1999
-
Ingår i: Physica scripta. T. - 0281-1847. ; 79, s. 206-208
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the properties of wafer-fused Si-doped isotype hetero-junctions between GaAs and InP. Current/voltage measurements were conducted to study the influence of the doping concentrations on each side of the interface on the electrical conductivity. An almost ohmic behavior with a very low series resistance was obtained for the highest examined doping level on the GaAs side, whereas the doping concentration on the InP side was found to be of little significance. Fusion at different temperatures showed that the conductivity degrades significantly below 500°C, although mechanically stable junctions were obtained also at temperatures as low as 305°C. Secondary ion mass spectroscopy measurements showed no redistribution of Si, but indicated the presence of small amounts of C and Fe impurities at the interface.
|
|
| 8. |
- Flanagan, J Randall, et al.
(författare)
-
Experience can change distinct size-weight priors engaged in lifting objects and judging their weights.
- 2008
-
Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 18:22, s. 1742-7
-
Tidskriftsartikel (refereegranskat)abstract
- The expectation that object weight increases with size guides the control of manipulatory actions [1-6] and also influences weight perception. Thus, the size-weight illusion, whereby people perceive the smaller of two equally weighted objects to be heavier, is thought to arise because weight is judged relative to expected weight that, for a given family of objects, increases with size [2, 7]. Here, we show that the fundamental expectation that weight increases with size can be altered by experience and neither is hard-wired nor becomes crystallized during development. We demonstrate that multiday practice in lifting a set of blocks whose color and texture are the same and whose weights vary inversely with volume gradually attenuates and ultimately inverts the size-weight illusion tested with similar blocks. We also show that in contrast to this gradual change in the size-weight illusion, the sensorimotor system rapidly learns to predict the inverted object weights, as revealed by lift forces. Thus, our results indicate that distinct adaptive size-weight maps, or priors, underlie weight predictions made in lifting objects and in judging their weights. We suggest that size-weight priors that influence weight perception change slowly because they are based on entire families of objects. Size-weight priors supporting action are more flexible, and adapt more rapidly, because they are tuned to specific objects and their current state.
|
|
| 9. |
|
|
| 10. |
|
|
