| 1. |
- Wadsö, Lars, et al.
(författare)
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Isothermal Titration Calorimetry in the Student Laboratory
- 2011
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Ingår i: Journal of Chemical Education. - : American Chemical Society (ACS). - 0021-9584 .- 1938-1328. ; 88:1, s. 101-105
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Tidskriftsartikel (refereegranskat)abstract
- Isothermal titration calorimetry (ITC) is the measurement of the heat produced by the stepwise addition of one substance to another. It is a common experimental technique, for example, in pharmaceutical science, to measure equilibrium constants and reaction enthalpies. We describe a stirring device and an injection pump that can be used with a previously described isothermal calorimeter to perform ITC measurements. Two experiments are also described: an acid−base titration and the binding of Ba2+ to the macrocyclic compound 18-crown-6. These experiments visualize the difference between strong and weak interactions (large and small equilibrium constants) and introduce how reaction enthalpies and equilibrium constants can be calculated from titration calorimetric experiments.
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| 2. |
- Frühwald, Eva, et al.
(författare)
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Image analysis study of mould susceptibility of spruce and larch wood dried or heat-treated at different temperatures
- 2008
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Ingår i: Wood Material Science & Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 3:1-2, s. 55-61
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Tidskriftsartikel (refereegranskat)abstract
- In this study, mould growth on wood was investigated by image analysis. The studied parameters were drying and heat-treatment temperatures (20-210°C), original and resawn surface and different wood species (spruce and larch). Small specimens—some of which were inoculated with a spore suspension—were stored under humid conditions and photographed once a week. Mould growth was assessed by image analysis. In general, results found in earlier studies regarding the influence of several parameters could be confirmed. Image analysis was found to be a useful method to quantify mould growth in an objective and reproducible way.
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| 3. |
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| 4. |
- Jiang, Bowen, 1993, et al.
(författare)
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A Novel Approach of Electric Powertrain Co-Simulation with High Fidelity Vehicle Model
- 2022
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Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2022-October
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Konferensbidrag (refereegranskat)abstract
- This paper presents a co-simulation approach for an electric vehicle which combines dynamic models of electric machine, inverter, gearbox in PLECS with high fidelity models of driver, autobody, wheel, road and environment in CarMaker. Lumped parameter thermal networks to model heat dissipation in the electric machine and the inverter are also included. The aim is to demonstrate versatility of the co-simulation method in analyzing effects of driver behaviors on thermal performance of electric machine and inverter. Co-simulation results using two simulation tools are compared to those obtained entirely using a single tool. It is observed that performing co-simulation using low fidelity vehicle model results in underestimation of vehicle speed. Further, the impacts of three different driver models on the temperatures of electric machine windings and semiconductor junctions are analyzed. Differences of 30% and 25% in the maximum temperature are observed respectively between an aggressive and a defensive driver.
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| 5. |
- Jiang, Bowen, 1993, et al.
(författare)
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Acceleration-based wheel slip control realized with decentralised electric drivetrain systems
- 2022
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Ingår i: IET Electrical Systems in Transportation. - : Institution of Engineering and Technology (IET). - 2042-9738 .- 2042-9746. ; 12:2, s. 143-152
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Tidskriftsartikel (refereegranskat)abstract
- Traction control is one of the most important functions in vehicle drivetrain systems. When a vehicle is driven on a low-friction road surface, loss of traction force can cause the driven wheels to spin. This reduces vehicle acceleration performance and can even cause the driver to lose control of the vehicle. The high bandwidth of electric machine control in electric vehicles gives more possibilities to regulate driving torque on wheels and prevent wheel spin. An acceleration-based wheel slip control is designed and investigated. Compared to traditional slip-based traction control, the proposed method does not depend on the estimation of the vehicle speed and only relies on the driven wheel rotational acceleration. The control method is verified using the simulation of an electric vehicle with a decentralised electric drivetrain system. The vehicle and the electric drive are modelled in CarMaker and PLECS, respectively. The simulation results show that the proposed method is able to prevent the driven wheel from spinning when the vehicle is accelerated on an ice road. In addition, the control is fast enough and requires only half a second to reduce the wheel acceleration to a normal range.
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| 6. |
- Jiang, Bowen, 1993, et al.
(författare)
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Real-Time FPGA/CPU-Based Simulation of a Full-Electric Vehicle Integrated with a High-Fidelity Electric Drive Model
- 2022
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 15:5
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Tidskriftsartikel (refereegranskat)abstract
- Real-time simulations refer to the simulations of a physical system where model equations for one time-step are solved within the same time period as in reality. An FPGA/CPU-based real-time simulation platform is presented in this paper, with a full-electric vehicle model implemented in a central processing unit (CPU) board and an electric drive model implemented in a field programmable gate arrays (FPGA) board. It has been a challenge to interface two models solved with two different processors. In this paper, one open-loop and three closed-loop interfaces are proposed. Real-time simulation results show that the best method is to transmit electric machine speed from the vehicle model to the electric derive model, with feedback electric machine torque calculated in FPGA. In addition, a virtual vehicle testing tool (CarMaker) is used when building the vehicle model, achieving more accurate modeling of vehicle subsystems. The presented platform can be used to verify advanced vehicle control functions during hardware-in-the-loop (HIL) testing. Vehicle anti-slip control is used as an example here. Finally, experiments were performed by connecting the real-time platform with a back-to-back electric machine test bench. Results of torque, rotor speed, and d&q axis currents are all in good agreement between simulations and experiments.
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| 7. |
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| 8. |
- Li, Bo, et al.
(författare)
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Contact mechanism of a rock fracture subjected to normal loading and its impact on fast closure behavior during initial stage of fluid flow experiment
- 2015
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Ingår i: International Journal for Numerical and Analytical Methods in Geomechanics. - : Wiley. - 0363-9061 .- 1096-9853. ; 39:13, s. 1431-1449
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Tidskriftsartikel (refereegranskat)abstract
- Fast closure of rock fractures has been commonly observed in the initial stage of fluid flow experiments at environmental temperatures under low or moderate normal stresses. To fully understand the mechanisms that drive this fast closure, the evolution of local stresses acting on contacting asperities on the fracture surfaces prior to fluid flow tests needs to be evaluated. In this study, we modeled numerically the asperity deformation and failure processes during initial normal loading, by adopting both elastic and elastic-plastic deformation models for the asperities on a real rock fracture with measured surface topography data, and estimated their impact on initial conditions for fluid flow test performed under laboratory conditions. Compared with the previous models that simulate the normal contact of a fracture as the approach of two rigid surfaces without deformations, our models of deformable asperities yielded smaller contact areas and higher stresses on contacting asperities at a given normal stress or normal displacement. The results show that the calculated local stresses were concentrated on the contacts of a few major asperities, resulting in crushing of asperity tips. With these higher contact stresses, however, the predicted closure rates by pressure solution are still several orders of magnitude lower than that of the experimental measurements at the initial stage of fluid flow test. This indicates that single pressure solution may not likely to be the principal compaction mechanism for this fast closure, and that the damages on contacting asperities that occur during the initial normal loading stage may play an important role.
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| 9. |
- Li, Bo, et al.
(författare)
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Experimental study of the hydro-mechanical behavior of rock joints using a parallel-plate model containing contact areas and artificial fractures
- 2008
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier BV. - 1365-1609 .- 1873-4545. ; 45:3, s. 362-375
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, geological disposal of radioactive wastes is considered to be the most promising option, which requires the understanding of the coupled mechanical, hydraulic and thermal properties of the host rock masses and rock fractures. The hydro-mechanical behavior and properties of rock fractures are usually determined by laboratory experiments on fracture specimens that serve as the basic building block of the constitutive models of fractured rock masses. Laboratory testing of rock fractures involve a number of technical issues that may have significant impacts on the reliability and applicability of the testing results, chief among them are the quantitative estimation of the evolutions of hydraulic transmissivity fields of fractures during shear under different normal constraint conditions, and the sealing techniques when fluid flow during shear is involved. In this study, a new shear-flow testing apparatus with specially designed fluid sealing techniques for rock fractures were developed, under constant normal load (CNL) or constant normal stiffness (CNS) constraint. The topographical data of all fracture specimens were measured before testing to constitute the geometrical models for simulating the change of mechanical aperture distributions during shearing. A number of shear-flow coupling tests were carried out on three kinds of rock fracture specimens to evaluate the influence of morphological properties of rock fractures on their hydro-mechanical behaviour. Some empirical relations were proposed to evaluate the effects of contact area and surface roughness on the behavior of fluid flow through rock fractures.
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| 10. |
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