| 1. |
- Ahlund, John, et al.
(författare)
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Molecular growth determined by surface domain patterns
- 2008
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:17, s. 6887-6890
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Tidskriftsartikel (refereegranskat)abstract
- The growth of iron phthalocyanine (FePc) on InSb(001) c(8 x 2) at submonolayer coverage has been investigated with scanning tunneling microscopy (STM). FePc adsorbs flat centered on the In rows both at 70 K and at room temperature (RT). However, the shapes of the two-dimensional molecular islands are fundamentally different; while the RT growth results in chainlike structures along the [I 10] direction, as already observed for other Pc's adsorbed on the same surface, the islands are prolonged along [110], i.e., perpendicular to the substrate rows, at 70 K. These observations are explained on the basis of a recently observed new surface phase at low temperature, resulting in structural domains on the surface. The molecular growth front follows the propagating domain boundary that freezes at low temperature.
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| 2. |
- Andreae, Christina, et al.
(författare)
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Patients' Participation as It Appears in the Nursing Documentation, When Care Is Ruled by Standardized Care Plans
- 2011
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Ingår i: ISRN Nursing. - : Hindawi Limited. - 2090-5483 .- 2090-5491. ; 2011:Article ID 707601, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to describe inpatients with myocardial infarction and their participation in care as documented in the nursing records when standardized care plans are used in care. The use of standardized care plans not only has increased the quality of medical treatment but has also overlooked patients' opportunities to participate in their own care. There is a lack of knowledge about how standardized care plans influence patients' participation in nursing care. Data were collected from thirteen patients' records with diagnoses of myocardial infarction. Participation in the decision-making process and participation associated with “sharing with others” were searched for in the analysis. The analytical process was guided by content analysis. The findings were grouped into two categories: patients' intermediary participation and patients' active participation. The main results indicated that patients' intermediary participation depended on healthcare professionals' power to rule the nursing care situation.
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| 3. |
- Arjmand, Doghonay, et al.
(författare)
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A FINITE ELEMENT HETEROGENEOUS MULTISCALE METHOD WITH IMPROVED CONTROL OVER THE MODELING ERROR
- 2016
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Ingår i: Communications in Mathematical Sciences. - : International Press of Boston. - 1539-6746 .- 1945-0796. ; 14:2, s. 463-487
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Tidskriftsartikel (refereegranskat)abstract
- Multiscale partial differential equations (PDEs) are difficult to solve by traditional numerical methods due to the need to resolve the small wavelengths in the media over the entire computational domain. We develop and analyze a Finite Element Heterogeneous Multiscale Method (FE-HMM) for approximating the homogenized solutions of multiscale PDEs of elliptic, parabolic, and hyperbolic type. Typical multiscale methods require a coupling between a micro and a macro model. Inspired from the homogenization theory, traditional FE-HMM schemes use elliptic PDEs as the micro model. We use, however, the second order wave equation as our micro model independent of the type of the problem on the macro level. This allows us to control the modeling error originating from the coupling between the different scales. In a spatially fully discrete a priori error analysis we prove that the modeling error can be made arbitrarily small for periodic media, even if we do not know the exact period of the oscillations in the media. We provide numerical examples in one and two dimensions confirming the theoretical results. Further examples show that the method captures the effective solutions in general non-periodic settings as well.
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| 4. |
- Arjmand, Doghonay, 1987-, et al.
(författare)
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A note on the Taylor s decomposition on four points for a third-order differential equation
- 2007
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Ingår i: Applied Mathematics and Computation. - : Elsevier. - 0096-3003 .- 1873-5649. ; 188:2, s. 1483-1490
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Tidskriftsartikel (refereegranskat)abstract
- Taylor's decomposition on four points is presented. three-step difference schemes generated by the Taylor's decomposition on fourpoints for the numerical solutions of an initial-value problem, a boundary-value problem, and a nonlocal boundary-value problem for a third-order ordinary differential equation are constructed. Numerical examples are given.
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| 5. |
- Arjmand, Doghonay, et al.
(författare)
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A time dependent approach for removing the cell boundary error in elliptic homogenization problems
- 2016
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Ingår i: Journal of Computational Physics. - : Elsevier. - 0021-9991 .- 1090-2716. ; 314, s. 206-227
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Tidskriftsartikel (refereegranskat)abstract
- This paper concerns the cell-boundary error present in multiscale algorithms for elliptic homogenization problems. Typical multiscale methods have two essential components: a macro and a micro model. The micro model is used to upscale parameter values which are missing in the macro model. To solve the micro model, boundary conditions are required on the boundary of the microscopic domain. Imposing a naive boundary condition leads to O(epsilon/eta) error in the computation, where epsilon is the size of the microscopic variations in the media and eta is the size of the micro-domain. The removal of this error in modern multiscale algorithms still remains an important open problem. In this paper, we present a time-dependent approach which is general in terms of dimension. We provide a theorem which shows that we have arbitrarily high order convergence rates in terms of epsilon/eta in the periodic setting. Additionally, we present numerical evidence showing that the method improves the O(epsilon/eta) error to O(epsilon) in general non-periodic media.
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| 6. |
- Arjmand, Doghonay, 1987-, et al.
(författare)
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Analysis of heterogeneous multiscale methods for long time wave propagation problems
- 2014
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Ingår i: Multiscale Modeling & simulation. - : Society for Industrial & Applied Mathematics (SIAM). - 1540-3459 .- 1540-3467. ; 12:3, s. 1135-1166
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we analyze a multiscale method developed under the heterogeneous multiscale method (HMM) framework for numerical approximation of multiscale wave propagation problems in periodic media. In particular, we are interested in the long time O(epsilon(-2)) wave propagation, where e represents the size of the microscopic variations in the media. In large time scales, the solutions of multiscale wave equations exhibit O(1) dispersive effects which are not observed in short time scales. A typical HMM has two main components: a macromodel and a micromodel. The macromodel is incomplete and lacks a set of local data. In the setting of multiscale PDEs, one has to solve for the full oscillatory problem over local microscopic domains of size eta = O(epsilon) to upscale the parameter values which are missing in the macroscopic model. In this paper, we prove that if the microproblems are consistent with the macroscopic solutions, the HMM approximates the unknown parameter values in the macromodel up to any desired order of accuracy in terms of epsilon/eta..
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| 7. |
- Arjmand, Doghonay, et al.
(författare)
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Estimates for the upscaling error in heterogeneous multiscale methods for wave propagation problems in locally periodic media
- 2017
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Ingår i: Multiscale Modeling & simulation. - : Society for Industrial and Applied Mathematics. - 1540-3459 .- 1540-3467. ; 15:2, s. 948-976
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Tidskriftsartikel (refereegranskat)abstract
- This paper concerns the analysis of a multiscale method for wave propagation problems in microscopically nonhomogeneous media. A direct numerical approximation of such problems is prohibitively expensive as it requires resolving the microscopic variations over a much larger physical domain of interest. The heterogeneous multiscale method (HMM) is an efficient framework to approximate the solutions of multiscale problems. In the HMM, one assumes an incomplete macroscopic model which is coupled to a known but expensive microscopic model. The micromodel is solved only locally to upscale the parameter values which are missing in the macro model. The resulting macroscopic model can then be solved at a cost independent of the small scales in the problem. In general, the accuracy of the HMM is related to how good the upscaling step approximates the right macroscopic quantities. The analysis of the method that we consider here was previously addressed only in purely periodic media, although the method itself is numerically shown to be applicable to more general settings. In the present study, we consider a more realistic setting by assuming a locally periodic medium where slow and fast variations are allowed at the same time. We then prove that the HMM captures the right macroscopic effects. The generality of the tools and ideas in the analysis allows us to establish convergence rates in a multidimensional setting. The theoretical findings here imply an improved convergence rate in one dimension, which also justifies the numerical observations from our earlier study.
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| 8. |
- Ashyralyev, Allaberen, et al.
(författare)
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Taylor's decomposition on four points for solving third-order linear time-varying systems
- 2009
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Ingår i: Journal of the Franklin Institute. - : Elsevier BV. - 0016-0032 .- 1879-2693. ; 346:7, s. 651-662
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Tidskriftsartikel (refereegranskat)abstract
- In the present paper, the use of three-step difference schemes generated by Taylor's decomposition on four points for the numerical solutions of third-order time-varying linear dynamical systems is presented. The method is illustrated for the numerical analysis of an up-converter used in communication systems.
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| 9. |
- Belin, Matts-Åke, 1966-, et al.
(författare)
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Vision Zero : a road safety policy innovation
- 2012
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Ingår i: International Journal of Injury Control and Safety Promotion. - : Informa UK Limited. - 1745-7319 .- 1745-7300. ; 19:2, s. 171-179
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Tidskriftsartikel (refereegranskat)
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| 10. |
- Castleton, Christopher, 1969-, et al.
(författare)
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Correlations between magnetic properties and bond formation in Rh-MgO(001)
- 2007
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 601:5, s. 1218-1230
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of first principles calculations for the magnetism of Rh adlayers on MgO(001), at three different adsorption sites and three different coverages, corresponding to 1, 1/2 and 1/8 monolayers. Finite magnetization is found in all cases except that of one Rh monolayer above the oxygen site, which is also the most stable. We examine how the magnetization changes as a function of the Rh-surface distance and relate this to changes in the real-space charge density and in the density of states (DOS) as the Rh adlayer interacts with the surface. We find that increasing either the Rh-Rh interaction strength or the Rh-surface interaction strength leads to reduced magnetization, while increasing the former drives a crossover from localized (atomic) to itinerant magnetism. Neither the magnetic transition itself, nor the localized-to-itinerant magnetism crossover, is found to be directly related to the formation of Rh-surface bonds. From a practical point of view, we predict that magnetism in the Rh-MgO(001) system is most likely to be found experimentally at reduced coverages and at low temperatures.
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