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Search Results: 1 - 10 of 1189 matches for " Ola Wilhelmsson "
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Carbon release by selective alloying of transition metal carbides
Mikael R?sander,Erik Lewin,Ola Wilhelmsson,Biplab Sanyal,Mattias Klintenberg,Olle Eriksson,Ulf Jansson
Physics , 2011, DOI: 10.1088/0953-8984/23/35/355401
Abstract: We have performed first principles density functional theory calculations on TiC alloyed on the Ti sublattice with 3d transition metals ranging from Sc to Zn. The theory is accompanied with experimental investigations, both as regards materials synthesis as well as characterization. Our results show that by dissolving a metal with a weak ability to form carbides, the stability of the alloy is lowered and a driving force for the release of carbon from the carbide is created. During thin film growth of a metal carbide this effect will favor the formation of a nanocomposite with carbide grains in a carbon matrix. The choice of alloying elements as well as their concentrations will affect the relative amount of carbon in the carbide and in the carbon matrix. This can be used to design the structure of nanocomposites and their physical and chemical properties. One example of applications is as low-friction coatings. Of the materials studied, we suggest the late 3d transition metals as the most promising elements for this phenomenon, at least when alloying with TiC.
A novel wear-resistant magnetic thin film material based on a $Ti_{1-x}Fe_xC_{1-y}$ nanocomposite alloy
Stojanka Bijelovic,Mikael R?sander,Ola Wilhelmsson,Erik Lewin,Biplab Sanyal,Ulf Jansson,Olle Eriksson,Peter Svedlindh
Physics , 2009, DOI: 10.1103/PhysRevB.81.014405
Abstract: In this study we report on the film growth and characterization of thin (approximately 50 nm thick) Ti-Fe-C films deposited on amorphous quartz. The experimental studies have been complemented by first principles density functional theory (DFT) calculations. Upon annealing of as-prepared films, the composition of the metastable Ti-Fe-C film changes. An iron-rich phase is first formed close to the film surface, but with increasing annealing time this phase is gradually displaced toward the film-substrate interface where its position stabilizes. Both the magnetic ordering temperature and the saturation magnetization changes significantly upon annealing. The DFT calculations show that the critical temperature and the magnetic moment both increase with increasing Fe and C-vacancy concentration. The formation of the metastable iron-rich Ti-Fe-C compound is reflected in the strong increase of the magnetic ordering temperature. Eventually, after enough annealing time ($\geq 10$ minutes), nano-crystalline $\alpha$-Fe starts to precipitate and the amount and size of these precipitates can be controlled by the annealing procedure; after 20 minutes of annealing, the experimental results indicate a nano-crystalline iron-film embedded in a wear resistant TiC compound. This conclusion is further supported by transmission electron microscopy studies on epitaxial Ti-Fe-C films deposited on single crystalline MgO substrates where, upon annealing, an iron film embedded in TiC is formed. Our results suggest that annealing of metastable Ti-Fe-C films can be used as an efficient way of creating a wear-resistant magnetic thin film material.
Anisotropy in the electronic structure of V2GeC investigated by soft x-ray emission spectroscopy and first-principles theory
Martin Magnuson,Ola Wilhelmsson,Maurizio Mattesini,Sa Li,Rajeev Ahuja,Olle Eriksson,Hans H?gberg,Lars Hultman,Ulf Jansson
Physics , 2011, DOI: 10.1103/PhysRevB.78.035117
Abstract: The anisotropy of the electronic structure of ternary nanolaminate V2GeC is investigated by bulk-sensitive soft x-ray emission spectroscopy. The measured polarization-dependent emission spectra of V L2,3, C K, Ge M1 and Ge M2,3 in V2GeC are compared to those from monocarbide VC and pure Ge. The experimental emission spectra are interpreted with calculated spectra using ab initio density-functional theory including dipole transition matrix elements. Different types of covalent chemical bond regions are revealed; V 3d - C 2p bonding at -3.8 eV, Ge 4p - C 2p bonding at -6 eV and Ge 4p - C 2s interaction mediated via the V 3d orbitals at -11 eV below the Fermi level. We find that the anisotropic effects are high for the 4p valence states and the shallow 3d core levels of Ge, while relatively small anisotropy is detected for the V 3d states. The macroscopic properties of the V2GeC nanolaminate result from the chemical bonds with the anisotropic pattern as shown in this work.
Grupp 1. Hjordsammans ttning
Martin Wilhelmsson (moderator)
Rangifer , 1982,
Abstract: Gruppens anbefalinger er finne i fullstendig pdf
A model for analyzing influence of timber production on lichens for reindeer grazing
Olof Eriksson,Mats Sandewall,Erik Wilhelmsson
Rangifer , 1987,
Abstract: A model for long-term analysis of the influence of timber production on lichens for reindeer grazing (Cladina, Alectoria, Bryoria spp and others) in Sweden is presented. The annual production of and demand for lichens are estimated and compared. Production of these lichens is presumed to set the upper limit for the reindeer population. Reindeer graze on both ground and tree lichens, which both must be accessible in sufficient amounts and at the right times of the year if reindeer husbandry is to succeed without supplementary feeding. The model is based mainly on existing data, and uses are estimations from the National Forest Survey and the Hugin system for calculation of longterm potential cut (Bengtsson, 1981). Geographically the study is limited to Vasterbotten and Norrbotten, the northernmost counties in Sweden, where most reindeer husbandry in Sweden is located, and where reindeer grazing takes place over almost the whole area. The calculations cover a period of one hundred years from 1980, and are based on a timber production programme which relies more on multiple use than the current Swedish forest policy (Bengtsson, 1986). The annual production of ground lichens is calculated by multiplying the area covered with ground lichens by their increment as estimated from their rate of biomass increase, which in turn depends on site factors and age of the stand. The estimation of the area is based on data from the National Forest Survey. Sample plots with ground lichens are assumed to maintain lichens during the whole hundred year period. Areas with stands that have been thinned within ten years and stands younger than 20 years are excluded due to logging residues from thinnings and packed snow. Some of the remaining area cannot practically be utilized for reindeer grazing. Representatives of three communities of reindeer herders classified 212 plots from the National Forest Survey with ground lichens and assessed that 3/4 of the plots can be utilized. The reduction was because of location (near buildings, roads, railroads, and recreation facilities), or because the area with lichens was too small and isolatéd. Demand for ground lichens is calculated as the daily demand for ground lichens by the reindeer multiplied by the number of days every year that reindeer depend on this forage. Figures used are based upon estimations from persons with great experience of reindeer farming. The annual production of tree lichens consists of two parts, i.e., tree lichens within reach of the reindeer, and tree lichens which become accessible after falling down from th
A Critique of Mcdowell’s Demonstrative Thought in the Cognitive Process of Perception  [PDF]
Emmanuel Ola Akintona
Open Journal of Philosophy (OJPP) , 2014, DOI: 10.4236/ojpp.2014.43045

The recent trend in epistemology is the consideration about the possibility of non-conceptual content in the cognitive process of perception. This has ever been generating serious polemics amongphilosophers of perception on the true nature and character of the content of our perceptual experienceat perception. Two groups eventually emerged: the non-conceptualists and the conceptualists. The non-conceptualists on one hand advocate that mental representations of the world do not necessarily presuppose concepts by means of which the content of these representations can be specified, hence, cognizers can have mental representation of the world that are non-conceptual. They argue that creatures without conceptual capacity can be in a content-bearing state even though they lack concept, memory or linguistic ability. The conceptualists on the other hand claim that non-conceptual content neither exists nor is representationally significant to perception because they are mere qualitative content of sensation i.e. purely sensory content. For them, cognizers can only have mental representations of the world if they possess adequate concepts by means of which they can specify what they represent else their experience is unavoidable conceptual. John McDowell (1994), a leading conceptualist, therefore introduced the concept “demonstrative thought” to counter non-conceptuality. For him, no perceptual experience is indescribable or indemonstrable: a demonstrative concept like “that shade” is also a demonstrable concept. This paper adopts the philosophical conceptual analytic tool to argue that the introduction of demonstrative concepts by McDowell does not in any way hinder the possibility of non-conceptual content in perception.

A Return to Objective Ethics in Business Education: A Faith Based Argument for Plato’s Virtue Ethics  [PDF]
Christian Ola, Eric Sartell
Open Journal of Business and Management (OJBM) , 2014, DOI: 10.4236/ojbm.2014.23020
Abstract: Business ethics is an idea that many students and practitioners believe cannot exist together, often the result of religious underpinnings and philosophical debates deemed too “soft”. It is our belief, however, that business ethics is quite relevant given the current landscape and that a new model should be introduced immediately to all business schools that hope to produce future business leaders, not just business people. This model implements proven neurological traits inherent to all people into widely accepted virtue-based ethical teaching of the world’s major religions, and by doing so, a new framework for teaching what was once an awkward discipline into an interactive, highly-applicable theory.
Strategic Coordination for Sustainable Investment in Critical Infrastructure  [PDF]
Jeremiah Mutamba, Ola Busari
Journal of Geoscience and Environment Protection (GEP) , 2014, DOI: 10.4236/gep.2014.25011

In demonstrating the prime place of infrastructure investment in its national long-term development framework encapsulated in Vision 2030, as well as in the related New Growth Path, South Africa recently put together a comprehensive National Infrastructure Plan. Aside from mapping out short and medium-term priorities for scaling up investment in strategic sectors and enhancing infrastructure links across the country, the initiative underscores development objectives such as community empowerment and skills development. This paper zeroes into one of the 18 strategic programs in the plan—specifically devoted to water and sanitation infrastructure—and presents the principal elements for pursuing effective inter-project coordination and integration, as well as, ultimately, for ensuring the sustainable implementation of critical infrastructure. The approaches that have influenced the success of strategic coordination include participatory planning, project prioritization, regular tracking and unblocking of implementation hurdles, localization, active stakeholder engagement and ongoing program integration.

The Place of Concept in Human Cognitive Process of Perception: Why the Conceptualists Cannot Be Right?  [PDF]
Emmanuel Ola Akintona
Open Journal of Philosophy (OJPP) , 2015, DOI: 10.4236/ojpp.2015.51011
Abstract: There have been so many controversies in the meaning of concept and particularly its place in the cognitive process of perception. The conceptualists, particularly, John McDowell, D. W. Hamlyn, Bill Brewer and Sonia Sedivy, argue that the content of perceptual experience is always in a kind of relation with propositional attitude such that beliefs, judgments, hopes and aspirations are instantaneously captured in perception. If this is granted, then, it becomes difficult to admit the possibility of non-conceptuality in perception. But, on a critical look at the conceptualists’ arguments and deductions, we discover that the conceptualists conflate sensation with perception and concept formation. In view of this, this paper examines and does a critical analysis of the meaning of concept with the belief that if its place in the cognitive process of perception is determined and ascertained, the long standing problem about the nature and characterization of the content of human perceptual experience will automatically dissolve. Whilst distinguishing and separating sensation from perception, the paper establishes that concept-formation is not generic to perception and that there is a place for non-conceptuality in perception. This paper employs conceptual analytical tools to explain the place of concept, sensation and perceptual experience in the cognitive process of perception and thus establishes the truism of non-conceptuality in perception.
Fueling Water-Intensive Economic Growth: What Hope for Water Conservation?  [PDF]
Ola Busari, Jeremiah Mutamba
Journal of Geoscience and Environment Protection (GEP) , 2015, DOI: 10.4236/gep.2015.36014

In virtually every country has strategies for pursuing greater broad-based economic growth and fighting poverty and inequality that underscore the pivotal role of water, including its availability in reasonable quantity and desired quality. While GDP growth in South Africa slowed down from 2.2% in 2013 to 1.5% in 2014, and while there are suggestions that current growth drivers are weak and inflation drivers strong, hopes remain for moderate economic growth of upwards of 2.5% going forward. Aside from stabilizing power supply and securing an upward movement in consumer confidence, such optimism rests on the return of mining and manufacturing activities to their previously high levels, with implications for water requirements. Growing demand for water-intensive growth will be occurring side-by-side with the expanding needs of urbanization and social advancement, in the face of an increasing threat of climate change, recurring droughts, environmental pollution and limited accessible water resources. Effective reconciliation of the demand and supply of water would require the strengthening of water conservation and demand management beyond their currently low to moderate levels, calling for a paradigmatic shift in approaches to water management, sound appreciation of the potential benefits vis-à-vis the allocation of requisite resources and firm political leadership and support.?

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