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• 301.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Embodied energy and CO2 emission of wood- and concrete-framed buildings in Sweden: 2nd World Biomass Conference, Rome, Italy2004Konferensbidrag (Övrigt vetenskapligt)
• 302.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Variability in energy and carbon dioxide balances of wood and concrete building materials2006Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 41, nr 7, s. 940-951Artikel i tidskrift (Refereegranskat)

A variety of factors affect the energy and CO2 balances of building materials over their lifecycle. Previous studies have shown that the use of wood for construction generally results in lower energy use and CO2 emission than does the use of concrete. To determine the uncertainties of this generality, we studied the changes in energy and CO2 balances caused by variation of key parameters in the manufacture and use of the materials comprising a wood- and a concrete-framed building. Parameters considered were clinker production efficiency, blending of cement, crushing of aggregate, recycling of steel, lumber drying efficiency, material transportation distance, carbon intensity of fossil fuel, recovery of logging, sawmill, construction and demolition residues for biofuel, and growth and exploitation of surplus forest not needed for wood material production. We found the materials of the wood-framed building had lower energy and CO2 balances than those of the concrete-framed building in all cases but one. Recovery of demolition and wood processing residues for use in place of fossil fuels contributed most significantly to the lower energy and CO2 balances of wood-framed building materials. We conclude that the use of wood building material instead of concrete, coupled with greater integration of wood by-products into energy systems, would be an effective means of reducing fossil fuel use and net CO2 emission to the atmosphere.

• 303.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Joanneum Research, Graz, Austria. Force Consulting Ltd, Rotorua, New Zealand.
Preface - Special issue: Efficient USE of biomass for mitigating climate change2006Ingår i: Mitigation and Adaptation Strategies for Global Change, ISSN 1381-2386, E-ISSN 1573-1596, Vol. 11, nr 5-6, s. 933-934Artikel i tidskrift (Refereegranskat)
• 304.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Substituting Fossil Fuels with Biomass1996Ingår i: Energy Conversion and Management, ISSN 0196-8904, Vol. 37, nr 6/8, s. 1211-1216Artikel i tidskrift (Refereegranskat)
• 305.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
Efficient Use of Forest Resources2003Ingår i: International Nordic Bioenergy Conference, September 3-5, 2003, Finland, 2003, s. 165-170Konferensbidrag (Övrigt vetenskapligt)
• 306. Gutman, I.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Estimating and approximating the total pi-electron energy of benzenoid hydrocarbons2000Ingår i: Zeitschrift fur Naturforschung A-A Journal of Physical Sciences, ISSN 0932-0784, E-ISSN 1865-7109, Vol. 55, nr 5, s. 507-512Artikel i tidskrift (Refereegranskat)

Lower and upper bounds as well as approximate formulas for the total pi-electron energy (E) of benzenoid hydrocarbons are deduced, depending only on the number of carbon atoms (n) and number of carbon-carbon bonds (m). These are better than the several previously known (n, m)-type estimates and approximations for E.

• 307. Gwinner, G.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Influence of magnetic fields on electron-ion recombination at very low energies2000Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 84, nr 21, s. 4822-4825Artikel i tidskrift (Refereegranskat)

Radiative recombination (inverse photoionization) is believed to be well understood since the beginning of quantum mechanics. Still, modern experiments consistently reveal excess recombination rates at very low electron-ion center-of-mass energies. In a detailed study on recombination of F and C ions with magnetically guided electrons we explored the yet unexplained rate enhancement, its dependence on the magnetic field B, the electron density n(e), and the beam temperatures T-perpendicular to and T-parallel to. The excess scales as T-perpendicular to(-1/2) and, surprisingly, as T-parallel to(-1/2), increases strongly with B, and is insensitive to n(e). This puts strong constraints on explanations of the enhancement.

• 308. Hansson, O
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Arbetstillfredsställelse i kundteam: en fallstudie på Frigoscandia Distribution AB (examensarbete)2002Rapport (Övrigt vetenskapligt)
• 309.
Luleå University of Technology.
Luleå University of Technology. Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
How successful Swedish organisations achieve sustaniable health2005Ingår i: International Journal of Management Practice, ISSN 1477-9064, E-ISSN 1741-8143, Vol. 1, nr 3, s. 233-250Artikel i tidskrift (Refereegranskat)

The costs connected to the rapidly increasing sick leaves have risen to alarming levels in Sweden and, for instance, Norway and the Netherlands. To find out how to handle the situation on an organizational level, a case study of two organizations has been carried out, which are recognized and have been awarded for their excellence in methodologies for decreasing the number of sick leaves. One is a small manufacturing company and the other one is a large public health care organization. Both organizations are non-hierarchical with responsibility and authority delegated to different groups. The data collection has mainly been carried out through brainstorming in groups, structured in tree diagrams, complemented by interviews. Important working methods for mangers are low-prestige, visibility and functioning as coaches with activities aimed at building relations. On the basis of the result of this study, suggestions are presented which are considered possible for others to adopt.

• 310.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Kompostering av organiskt avfall i jämtländsk glesbygd - en förstudie1998Rapport (Övrigt vetenskapligt)
• 311. Havila, V
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
International business-relationship triads2004Ingår i: International Marketing Review, ISSN 0265-1335, E-ISSN 1758-6763, Vol. 21, nr 2, s. 172-186Artikel i tidskrift (Refereegranskat)

• 312. Hayderer, G.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Threshold for Potential Sputtering of LiF1999Ingår i: Physical Review Letters, ISSN 0031-9007, Vol. 83, nr 19, s. 3948-3951Artikel i tidskrift (Refereegranskat)

• 313. He, J H
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Research progress on biomass fuel ethanolManuskript (Övrig (populärvetenskap, debatt, mm))

Advances of domestic and overseas biomass fuel ethanol is outlined in this paper. Having evaluated its economic, energy, environmental and social benefits, thereafter its importance as a part of Chinese energy strategy had been confirmed. Finally, a feasible scheme for fuel ethanol production from biomass in large scale is suggested, used for reference.

• 314.
Huazhong University of Science and Technology, Wuhan, 430074, China.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
A study on latent heat storage exchangers with the high-temperature phase-change material2001Ingår i: International Journal of Energy Research, ISSN 0363-907X, Vol. 25, nr 4, s. 331-341Artikel i tidskrift (Refereegranskat)

This paper presents a theoretical analysis and an experimental test on a shell-and-tube latent heat storage exchanger. The heat exchanger is used to recover high temperature waste heat from industrial furnaces and off-peak electricity. It can also be integrated into a renewable energy system as an energy storage component. A mathematical model describing the unsteady freezing problem coupled with forced convection is solved numerically to predict the performance of the heat exchanger. It provides a basis for optimum design of the heat exchanger. The experimental study on the heat exchanger is carried out under various operating conditions. Effects of various parameters, such as the inlet temperature, the mass flow rate, the thickness of the phase change material and the length of the pipes, on the heat transfer performance of the unit are discussed by combining with theoretical prediction. Criterion for analyzing and evaluating the performance of heat exchanger is also proposed.

• 315.
Umeå universitet.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Resultat och erfarenheter av nationella prov på gymnasiet2000Ingår i: Dokumentation av 11:e Matematikbiennalen, Göteborg 27-29 januari 2000: tid för matematik, Göteborg: Nationellt centrum för matematikutbildn., Univ. , 2000, s. 679-Konferensbidrag (Övrigt vetenskapligt)
• 316. Hemmers, O.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Dipole and nondipole angular-distribution effects in valence photoemission from neon2002Ingår i: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, Vol. 123, nr 2-3, s. 257-264Artikel i tidskrift (Refereegranskat)

Nondipole angular-distribution parameters γ and δ for neon 2s and 2p photoelectrons have been measured and are compared to all available theoretical data. The agreement is very good throughout the 150-1200 eV photon-energy range studied. Furthermore, the neon 2p dipole angular-distribution parameter β and the 2s to 2p cross-section ratio have been measured throughout the same photon-energy range. The agreement between theoretical data and experiment is excellent.

• 317.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Aspects of predicting fracture in paper with the cohesive zone model combined with an elastic-plastic material model with kinematical hardening2004Rapport (Övrigt vetenskapligt)
• 318.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Determination of the cohesive stress-displacement relation aimed at prediction of fracture in paper2003Rapport (Övrigt vetenskapligt)
• 319. Hemp, John
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Problems in the Theory and Design of Electromagnetic Flowmeters for Dielectric Fluids: Part 1: Experimental Assessment of Static Charge Noise Levels and Signal-to-Noise Ratio2002Ingår i: Flow Measurement and Instrumentation, ISSN 0955-5986, E-ISSN 1873-6998, Vol. 13, nr 4, s. 143-145Artikel i tidskrift (Refereegranskat)

This paper reports on experimental measurements of electrode signal noise spectra in an electromagnetic flowmeter designed for

flow measurement of the dielectric liquid BP180. The design of the flowmeter tube and the detection electronics is described.

Dependence of the noise spectra on flow rate, electrode dimensions and particle content of the liquid is reported. Implications for

flowmeter tube design and for the choice of frequency of operation to achieve reasonable signal-to-noise ratios are explained.

• 320. Holm, P
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Solidification Experiments in Mirror Furnaces Flown in a GAS Payload on Space Shuttle STS-1082003Ingår i: Proceedings of the 16th ESA Symposium on European Rocket and Balloon Programmes and Related Research, 2003, s. 113-117Konferensbidrag (Övrigt vetenskapligt)

Solidification Experiments in Mirror Furnaces Flown in a GAS Payload on Space Shuttle STS-108

• 321.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Cross-country Skiing Biomechanics using the AnyBody Modeling System2007Ingår i: ANSYS Conference & 25th CADFEM Users´ Meeting 2007, Dresden, 2007Konferensbidrag (Refereegranskat)
• 322.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Optimering av biomekaniska system2001Ingår i: SMD 01 - Svenska mekanikdagar Linköping 11-13 juni 2001: Svenska mekanikdagar (2001 : Linköping), Stockholm: Svenska nationalkommittén för mekanik , 2001, s. 195-Konferensbidrag (Övrigt vetenskapligt)
• 323.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Using Double‐Poling Simulations to Study the Load Distribution between Teres Major and Latissimus Dorsi2007Ingår i: Science and Nordic Skiing, Oxford: Meyer & Meyer Sport, 2007, s. 81-89Konferensbidrag (Refereegranskat)
• 324.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
VerOpt - MATLAB Driven Versatile Optimization2001Ingår i: Program and proceedings for the Nordic MATLAB Conference Oslo, October 17-18, 2001, Trondheim: Comsol , 2001, s. 207-212Konferensbidrag (Övrigt vetenskapligt)

VerOpt, a MATLAB driven versatile optimization environment, enables the choice of a suitable optimization routine, parallelization over TCP/IP and the use of external solvers. VerOpt is the result of working towards the creation of a versatile yet effective environment for applied optimization studies. This paper presents the concepts behind VerOpt, including how and why we use parallelization, and the lessons learnt when using external solvers. The paper also gives a comparison of implemented optimization routines when applied to test problems. Currently, links to three external solvers are implemented. Two of them come from the commercial software market for engineering solutions: ANSYS (version 5.6 University High), a general purpose FE-code and C-MOLD (version 2000.7.1), a code for injection molding. The third solver is from the academic world, AnyBody, a code for biomechanical studies. The implemented optimization routines referred to are Method of Moving Asymptotes (MMA), Simulated Annealing (SA) and a genetic algorithm (GA). The MMA is a gradient-based algorithm whereas the other two can be classified as stochastic. The results of the comparison of the implemented optimization routines, in which �fmincon� from the MATLAB Optimization Toolbox is also used, show that MMA is generally the fastest routine, but does not always find the best solution. However, in test cases when parallelization is used the comparison is not ideal, since the parallelization procedures for the algorithms are not equivalent. When optimization routines are based on numerically computed gradients, such as MMA, they are embarrassingly parallel. This is because the gradients are independent of each other, which makes it possible to compute them simultaneously, but on different processors. For a stochastic routine such as SA a different approach is needed. In our case we have used a simple form of domain decomposition. An interesting result is that, in the test case involving ANSYS, we found that using ANSYS alone, as solver as well as optimizer, did not give such a good solution as using VerOpt. A clear future development is to add a greater number of different types of optimization routines. A possible future development is to transform VerOpt into something that is more akin to a regular style MATLAB Toolbox. Irrespective of this development, VerOpt will be a significant aid for education as well as research in applied optimization. It will also serve the authors as the environment for further research in the fields of injection molding and biomechanics.

• 325.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
A biomechanical model of a double-poling skier2003Ingår i: International Society of Biomechanics XIXth Congress, 6-11 July 2003, Dunedin, New Zealand, CD ROM - Abstracs and Proceeding, Dunedin, N.Z: University of Otago , 2003Konferensbidrag (Refereegranskat)

Up till now, very little has been done in the field of cross-country skiing biomechanics using numerical techniques. This paper presents a biomechanical model of a double-poling skier that is created with the use of AnyBody, a general body-modeling and optimization software. As an aid to validate the model, a physical experiment is performed. An elite female skier is video-taped while using a double-poling ergometer. This experiment provides measurements of movement and poling power. Simulation results agree well with an experiment concerning muscle activation sequences (Nilsson and Holmberg, 2000). However, when simulation results and measured poling power are compared, agreement is not good. This means that further work on the biomechanical model is needed before it can be validated as a good representation of reality. Still, the method shows potential, and the present model could be used for initial studies of the double-poling technique. When the model is validated, it could provide a very useful tool in the quest for gold medals and perhaps, more importantly, for the prevention of injuries.

• 326.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Efficient use of wood - a comparison between chemical and mechanical pulping2005Ingår i: Proceedings of the 14th European Biomass Conference and exhibition: Biomass for Energy, Industry and Climate Protection, Florence: ETA - Renewable energies , 2005Konferensbidrag (Övrigt vetenskapligt)

The pulp and paper industry is energy intensive and consumes large amounts of wood. Here, the total biomass use is estimated for the production of one tonne paper in a cradle-to-factory gate scope, assuming that all energy, including electricity and motor fuels, are produced from forest biomass. We consider the production of newsprint made from mechanical pulp; lightweight coated paper from a mixture of mechanical and chemical pulp; and fine paper from chemical pulp, under Swedish conditions. The results indicate that chemical pulp papers require less biomass resources per tonne of paper produced than do mechanical pulp papers. For mechanical pulp papers, external electricity requires the largest part of the biomass. Motor fuel production accounts in no case for more than 10%. Between 27% and 38% of the total biomass used is embodied in the paper product, indicating that waste paper recovery options are important.

• 327.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Biomass use in chemical and mechanical pulping with biomass-based energy supply2007Ingår i: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 52, nr 2, s. 331-350Artikel i tidskrift (Refereegranskat)

The pulp and paper industry is energy intensive and consumes large amounts of wood. Biomass is a limited resource and its efficient use is therefore important. In this study, the total amount of biomass used for pulp and for energy is estimated for the production of several woodfree (containing only chemical pulp) and mechanical (containing mechanical pulp) printing paper products, under Swedish conditions. Chemical pulp mills today are largely self-sufficient in energy while mechanical pulp mills depend on large amounts of external electricity. Technically, all energy used in pulp- and papermaking can be biomass based. Here, we assume that all energy used, including external electricity and motor fuels, is based on forest biomass. The whole cradle-to-gate chain is included in the analyses. The results indicate that the total amount of biomass required per tonne paper is slightly lower for woodfree than for mechanical paper. For the biomass use per paper area, the paper grammage is decisive. If the grammage can be lowered by increasing the proportion of mechanical pulp, this may lower the biomass use per paper area, despite the higher biomass use per unit mass in mechanical paper. In the production of woodfree paper, energy recovery from residues in the mill accounts for most of the biomass use, while external electricity production accounts for the largest part for mechanical paper. Motor fuel production accounts for 5–7% of the biomass use. The biomass contained in the final paper product is 21–42% of the total biomass use, indicating that waste paper recovery is important. The biomass use was found to be about 15–17% lower for modelled, modern mills compared with mills representative of today's average technology.

• 328. Holmberg,, Jonas M
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Efficient wood use - a comparison between chemical and mechanical pulping2005Ingår i: Biomass for energy, industry and climate protection :: 14th European Biomass Conference & Exhibition ; proceedings of the international conference held in Paris, France, 17 - 21 October 2005, [Florence]: ETA-Renewable Energies, , 2005Kapitel i bok, del av antologi (Övrigt vetenskapligt)

The pulp and paper industry is energy intensive and consumes large amounts of wood. Here, the total biomass use is estimated for the production of one tonne paper in a cradle-to-factory gate scope, assuming that all energy, including electricity and motor fuels, are produced from forest biomass. We consider the production of newsprint made from mechanical pulp; lightweight coated paper from a mixture of mechanical and chemical pulp; and fine paper from chemical pulp, under Swedish conditions. The results indicate that chemical pulp papers require less biomass resources per tonne of paper produced than do mechanical pulp papers. For mechanical pulp papers, external electricity requires the largest part of the biomass. Motor fuel production accounts in no case for more than 10%. Between 27% and 38% of the total biomass used is embodied in the paper product, indicating that waste paper recovery options are important.

• 329.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Systems aspects on new energy technologies in the pulp and paper industry2007Ingår i: Proceedings. 3rd International Green Energy Conference IGEC-III June 18 - 20, 2007 Västerås, Sweden, 2007Konferensbidrag (Refereegranskat)

Concerns about energy security, energy prices, and the impact of energy use on the global climate have put focus on ways to reduce CO2 emissions and oil dependency. In this paper we examine consequences of new energy technologies in the pulp and paper industry and estimate the costs for achieving certain CO2 emissions and oil use reductions with different pulp mill technologies. Stand-alone production of electricity and transportation fuel from biomass is included to balance the systems compared, so that they produce the same CO2 emission and oil use reductions. The technologies considered are black liquor gasification (BLG) with electricity and motor fuels production in chemical pulp mills and increased energy efficiency in mechanical pulp mills. The entire production chain from the extraction of primary resources is included in the analysis. Changes in the production chain are assumed to affect energy production on the margin. The technology alternatives are evaluated with respect to five parameters: Net CO2 emission, oil use, primary energy use, biomass use and monetary cost. We find that BLG in chemical pulp mills is favourable compared to stand-alone production of fuels and electricity from biomass. If both CO2 emission reductions and oil use reductions are to be achieved, it is more efficient to implement BLG with motor fuels production and stand-alone electricity production from biomass, than to implement BLG with electricity production and stand-alone production of motor fuels. Increased energy efficiency in refining of thermomechanical pulp is found to achieve CO2 savings more efficiently than stand-alone production of electricity from biomass.

• 330.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för humanvetenskap, Institutionen för hälsovetenskap.
The role of triceps in double poling biomechanics, an introductory study2007Ingår i: Proceedings of the 4th International Congress on Science and Skiing (2007). St. Cristoph am Aarlberg, Austria., 2007Konferensbidrag (Övrigt vetenskapligt)
• 331.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
A Darcy law for quasi-periodic porous media and optimal design of composite materials1996Ingår i: Proceedings of international Conference on Composites Engineering ICCE/3: 21-25/7 -96, New Orleans, LA, USA, 1996, s. 363-364Konferensbidrag (Övrigt vetenskapligt)
• 332.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
A model for non-linear nonstationary heat conduction in composites with many small nonperiodic perforations1997Ingår i: Proceedings of International Conference on Composites Engineering ICCE/4: 6-12/7, 1997, Hawaii, USA, 1997, s. 435-344Konferensbidrag (Övrigt vetenskapligt)
• 333.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Homogenization applied to some problems in mechanics1993Licentiatavhandling, monografi (Övrigt vetenskapligt)
• 334.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Homogenization in various kinds of quasi-periodic domains1995Rapport (Övrigt vetenskapligt)
• 335.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Homogenization of parabolic equations: an alternative approach and some corrector type results.1997Ingår i: Applications of Mathematics, ISSN 0862-7940, Vol. 42, nr 5, s. 321-343Artikel i tidskrift (Refereegranskat)

We extend and complete some quite recent results by Nguetseng and Allaire concerning two-scale convergence. In particular, a compactness result for a certain class of parameterdependent functions is proved and applied to perform an alternative homogenization procedure for linear parabolic equations with coefficients oscillating in both their space and time variables. For different speeds of oscillation in the time variable, this results in three cases. Further, we prove some corrector-type results and benefit from some interpolation properties of Sobolev spaces to identify regularity assumptions strong enough for suck results to hold.

• 336.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On homogenization and correctors for elliptic equations with mixed boundary conditions in periodic domains1995Rapport (Övrigt vetenskapligt)
• 337.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On homogenization applied to Stokes flow in porous media. A brief discussion of geometrical modelling and possible applications1992Ingår i: Proceedings of the Industrial Mathematics Week: Trondheim August 1992, Department of Mathematical Sciences, NTH, 1992, s. 152-159Konferensbidrag (Övrigt vetenskapligt)
• 338.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On homogenization theory and its application to optimal micro-design of composite materials1994Rapport (Övrigt vetenskapligt)
• 339.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On homogenization theory and its application to optimal micro-design of composite materials1994Ingår i: Proceedings of International Conference on Composites Engineering ICCE/1: New Orleans, LA, USA, Aug 28-31, 1994, 1994, s. 749-750Konferensbidrag (Övrigt vetenskapligt)
• 340.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Some modes of convergence and their application to homogenization and optimal composites design1996Doktorsavhandling, monografi (Övrigt vetenskapligt)

In this thesis, we develop, extend, apply, and discuss a number of methods for the study of limits of sequences of functions and operators. The connection between the notion of two-scale convergence and more general concepts of convergence is investigated and some alternative classes of admissible test functions are characterized. These techniques are extended into compactness results suitable to prove homogenization and corrector results for linear parabolic equations. A further refinement of these methods, together with a characterization of the limits of certain sequences of parameter-dependent functions which has been subject to extension from a quite general class of periodic domains, is introduced. This provides an efficient tool for the homogenization of e.g. nonlinear evolution heat conduction in heterogeneous materials which vibrate with high frequencies or are perforated by periodically arranged nonconducting holes. Moreover, we prove compactness and homogenization for sequences of solutions of linear elliptic and monotone parabolic equations defined in some classes of nonperiodic domains and derive a Darcy's law for a type of nonperiodic porous media. In the linear elliptic case the convergence is strengthened by means of correctors. Finally, we present some numerical results for homogenized stiffness of fibre composites and demonstrate how homogenization techniques for elasticity in composite materials and for liquid flow in porous media can be combined with recent optimization techniques to obtain optimal layout of composite materials.

• 341.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
The concept of parabolic two-scale convergence, a new compactness result and its application to homogenization of evolution partial differential equations1994Rapport (Övrigt vetenskapligt)
• 342.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Theorie des skis paraboliques1998Ingår i: L'Entraineur de ski alpin, ISSN 0983-9305, Vol. 27, nr septArtikel i tidskrift (Övrigt vetenskapligt)
• 343.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik. Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On the determination of limits for some sequences of functions and differential operators2006Ingår i: Canadian Applied Mathematics Quarterly, ISSN 1073-1849, Vol. 14, nr 3, s. 299-329Artikel i tidskrift (Refereegranskat)

This article deals with homogenization methods, namely two-scale convergence and Hconvergence, with the aim of comparing their efficiency in studying composite materials. Analytic examples are given to illustrate both methods. While compensated compactness allows one to determine the limit of a product of two weakly converging sequences under additional assumptions on the derivatives, two-scale convergence takes advantage of underlying oscillations of solution sequences and H-convergence is concerned with the operator behaviour. Special attention is paid to periodic homogenization as this case yields the most involved results. Numerical experiments are used to investigate open questions in H-convergence dealing with the possible relaxation of some convergence hypotheses. Partial results are established in this respect.

• 344.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
A homogenization procedure for computing effective moduli and micro stresses in elastic composite materials1992Ingår i: Composites Part B: Engineering, ISSN 1359-8368, Vol. 2, nr 4, s. 249-259Artikel i tidskrift (Refereegranskat)
• 345.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On a convergence result for sequences of functions with multiple scales2006Ingår i: Proceedings of the 9th WSEAS international conference on applied mathematics, Istanbul. Turkey., Aten: WSEAS press , 2006Konferensbidrag (Refereegranskat)
• 346.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On the characterization of effective properties in highly heterogeneous media2005Ingår i: IASME transactions / International ASsociation of Mechanical Engineers, ISSN 1790-031X, Vol. 2, s. 177-179Artikel i tidskrift (Refereegranskat)

We discuss methods related to homogenization theory and G-convergence for the computation of effective properties in heterogeneous materials. Especially we investigate a method to detect deviations from the arithmetic mean in heterogeneous materials that are not necessarily periodic.

• 347.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On the characterization of G-limits by means of some generalized two-scale techniques: Paper presented at the 26th Midwest-Pacific Differential Equations Conference, October 15-17, 2005, University of Alberta Edmonton, Alberta, Canada2005Konferensbidrag (Refereegranskat)

G-convergence usually deals with the convergence of sequences of elliptic or parabolic operators. When the convergence of the sequence of operators is strong enough, it is trivial to determine the $G$-limit. Other cases need sophisticated techniques for this aim, where the most well investigated case is periodic homogenization. The main tool of today for this purpose has become the so called two-scale convergence method by Nguetseng. This approach relies on a fundamental compactness result which says that for any bounded sequence $\left\{ u_{h}\right\}$ in $L^{2}\left( \Omega \right)$ there is $u_{0}\in L^{2}\left( \Omega \times Y\right)$ such that \begin{equation*} \dint\nolimits_{\Omega }u_{h}(x)\tau _{h}v(x)dx\rightarrow \dint\nolimits_{\Omega} \dint\nolimits_{Y}u_{0}(x,y)v(x,y)dxdy\end{equation*}% for any $v\in X=L^{2}(\Omega ;C_{\sharp }(Y))$ up to a subsequence, where% \begin{equation*} \tau _{h}v(x)=v(x,\frac{x}{\varepsilon _{h}}),\varepsilon _{h}\rightarrow 0% \text{.}\end{equation*} For gradients of sequences $\left\{ u_{h}\right\}$ bounded in $H^{1}\left( \Omega \right)$ the deviation from the week limit can be made explicit in terms of a local gradient $\nabla _{y}u_{1}$, $u_{1}\in L^{2}(\Omega;H_{\sharp }^{1}(Y))$, and this is the key to the characterization of the $G$%-limit. Similar techniques can be developed for other choices of the maps $\tau _{h}$ and admissible spaces $X$ which do not necessarily depend on any periodicity assumptions. We study such examples with respect to the possible appearance of residual terms corresponding to $\nabla _{y}u_{1}$ in periodic homogenization. In particular $G$-limits for problems, where the matrices defining the operators are generated by a kind of modified Hilbert-Schmidt operators, are investigated with respect to such deviations.

• 348.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On the convergence of some pairs of weakly convergent sequences: Presented at the Applmath05 Fourth conference on applied mathematics and scientific computing June 19-24 Brijuni Island, Croatia2005Konferensbidrag (Övrigt vetenskapligt)
• 349.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On the convergence of some sequences of oscillating functionals2006Ingår i: WSEAS transactions on mathematics, ISSN 1109-2769, Vol. 5, nr 8, s. 951-956Artikel i tidskrift (Refereegranskat)

We study an intermediate case between the two-scale convergence of Nguetseng and the more general concept of scale convergence of Mascarenhas and Toader. Suitable assumptions to provide scale convergence with some of the most essential properties of two-scale convergence are identified. Some aspects of the characterization of limits for sequences of gradients are discussed briefly.

• 350.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
On the characterization of effective properties in highly heterogeneous media (Proc.)2005Ingår i: Proceedings of the WSEAS HEAT '06, FLUID '06 : Elounda, Agios Nikolaos, Crete Island, Greece, August 21 - 23, 2006 ; 4th IASME/WSEAS International Conference on Heat Transfer, Thermal Engineering and Environment, 4th IASME/WSEAS International Conference on Fluid Mechanics and Aerodynamics Elounda, Greece, 2006, Elounda, Greece,, 2005, , s. -Konferensbidrag (Refereegranskat)

We discuss methods related to homogenization theory and G-convergence for the computation of effective properties in heterogeneous materials. Especially we investigate a method to detect deviations from the arithmetic mean in heterogeneous materials that are not necessarily periodic.

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