| 1. |
|
|
| 2. |
|
|
| 3. |
- Rodriguez, Juan Manuel, et al.
(författare)
-
Dislocation Density Based Material Model Applied in PFEM-simulation of Metal Cutting
- 2017
-
Ingår i: Procedia CIRP. - : Elsevier. - 2212-8271 .- 2212-8271. ; 58, s. 193-197
-
Tidskriftsartikel (refereegranskat)abstract
- Metal cutting is one of the most common metal-shaping processes. In this process, specified geometrical and surface properties are obtained through the break-up and removal of material by a cutting edge into a chip. The chip formation is associated with large strains, high strain rates and locally high temperatures due to adiabatic heating. These phenomena together with numerical complications make modeling of metal cutting challenging. Material models, which are crucial in metal-cutting simulations, are usually calibrated against data from material testing. Nevertheless, the magnitudes of strains and strain rates involved in metal cutting are several orders of magnitude higher than those generated from conventional material testing. Therefore, a highly desirable feature is a material model that can be extrapolated outside the calibration range. In this study, a physically based plasticity model based on dislocation density and vacancy concentration is used to simulate orthogonal metal cutting of AISI 316L. The material model is implemented into an in-house particle finite-element method software. Numerical simulations are in agreement with experimental results for different cutting speed and feed.
|
|
| 4. |
- Zhong, Jin, et al.
(författare)
-
Towards a 100% Renewable Energy Power Generation in Sweden
- 2016
-
Ingår i: Meeting Sweden's current and future energy challenges, Luleå: Luleå tekniska universitet, 2016. - Luleå : Luleå tekniska universitet.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 5. |
- Tabery, Helena
(författare)
-
Filamentary keratopathy: A non-contact photomicrographic in vivo study in the human cornea
- 2003
-
Ingår i: European Journal of Ophthalmology. - 1120-6721. ; 13:7, s. 599-605
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE. To investigate in vivo morphology of corneal filaments. MATERIALS AND METHODS. Over a 12-year period, 19 patients with corneal filaments (7 with keratoconjunctivitis sicca and 12 with other surface diseases) were examined with the slit lamp and photographed by non-contact photomicrography. RESULTS. The filaments appeared as variously long and thick threads, attached at one or both ends to the surface and carrying various amounts of granular and amorphous material. The attachment points and their surroundings showed abnormal cells and diffusion of tear fluid stained green with fluorescein sodium. The underlying stroma appeared normal. The remaining epithelium often showed abnormal surface cells and/or edematous or cystic changes. CONCLUSIONS. The in vivo morphology of filamentary keratopathy is consistent with aggregations of mucus and cell debris adhering to the corneal surface. The underlying diseases seem to have in common corneal epithelial edema. The nature of additional factors, or their combination, precipitating mucus adherence to the surface is not clear.
|
|
| 6. |
- Zhong, Jun, et al.
(författare)
-
Climate Variability Controls on CO2 Consumption Fluxes and Carbon Dynamics for Monsoonal Rivers : Evidence From Xijiang River, Southwest China
- 2018
-
Ingår i: Journal of Geophysical Research - Biogeosciences. - 2169-8953 .- 2169-8961. ; 123:8, s. 2553-2567
-
Tidskriftsartikel (refereegranskat)abstract
- The feedbacks of climate variability on CO2 consumption fluxes and carbon dynamics are thought to play an important role in moderating the global carbon cycle. High-frequency sampling campaigns and analyses were conducted in this study to investigate temporal variations of river water chemistry and the impacts of climate variability on CO2 consumption fluxes and carbon dynamics for the Xijiang River, Southwest China. Physical processes modify biogeochemical processes, so major ions display different responses to changing discharge. The annual CO2 consumption rate is (6.8 +/- 0.2) x 10(6) ton/year by carbonate weathering and (2.4 +/- 0.3) x 10(6) ton/year by silicate weathering. The annual CO2 consumption flux is much higher than most world rivers, and strong CO2 consumption capacities are observed in catchments in Southwest China. Lower negative delta C-13(DIC) values are found in the high-flow season which corresponds with high temperatures compared to those in the low-flow season. High discharge will accelerate material transport, and high temperatures will increase primary production in the catchment, both of which can be responsible for the shift of delta C-13(DIC) values in the high-flow season. Increased mineral weathering and biological carbon influx in the catchment are the main factors controlling carbon dynamics. Overall, these findings highlight the sensitivity of CO2 consumption fluxes and carbon dynamics in response to climate variability in the riverine systems. Plain Language Summary There are feedbacks between climate variability and CO2 consumption fluxes by chemical weathering and carbon dynamics. Significant temporal variations of major ions and delta C-13(DIC) are observed in the Xijiang River. Multiple biogeochemical processes occur under various hydrological conditions, shifting major ions concentrations, and delta C-13(DIC). The annual CO2 consumption rate is (6.8 +/- 0.2) x 10(6) ton/year by carbonate weathering and (2.4 +/- 0.3) x 10(6) ton/year by silicate weathering. The annual CO2 consumption rates in the Xijiang River only account for a small fraction in the global CO2 consumption rates; the CO2 consumption capacity is much higher than the global average, while much lower than its source tributaries (Beipan and Nanpan Rivers). Slow subsurface flow paths with longer transit times switch to rapid near-surface flow paths with shorter transit times, as discharge increases. High temperatures increase reaction rates, and high discharge rates remove transport limitation, both of which would accelerate the chemical weathering rates. In the high-flow season, high discharge accompanying with high temperatures, large amounts of delta C-13-depleted biological carbon, flushes into the river, affecting the carbon dynamics.
|
|
| 7. |
|
|
| 8. |
- di Bernardo, M., et al.
(författare)
-
Bifurcations in Nonsmooth Dynamical Systems
- 2008
-
Ingår i: SIAM Review. - : Society for Industrial & Applied Mathematics (SIAM). - 0036-1445 .- 1095-7200. ; 50:4, s. 629-701
-
Forskningsöversikt (refereegranskat)abstract
- A review is presented of the one-parameter, nonsmooth bifurcations that occur in a variety of continuous-time piecewise-smooth dynamical systems. Motivated by applications, a pragmatic approach is taken to defining a discontinuity-induced bifurcation (DIB) as a nontrivial interaction of a limit set with respect to a codimension-one discontinuity boundary in phase space. Only DIBs that are local are considered, that is, bifurcations involving equilibria or a single point of boundary interaction along a limit cycle for flows. Three classes of systems are considered, involving either state jumps, jumps in the vector field, or jumps in some derivative of the vector field. A rich array of dynamics are revealed, involving the sudden creation or disappearance of attractors, jumps to chaos, bifurcation diagrams with sharp corners, and cascades of period adding. For each kind of bifurcation identified, where possible, a kind of "normal form" or discontinuity mapping (DM) is given, together with a canonical example and an application. The goal is always to explain dynamics that may be observed in simulations of systems which include friction oscillators, impact oscillators, DC-DC converters, and problems in control theory.
|
|
| 9. |
|
|
| 10. |
- 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.
|
|
