Now showing items 21-40 of 617

    • Weighted Hardy-Type Inequalities in Variable Exponent Morrey-Type Spaces 

      Lukkassen, Dag; Persson, Lars Erik; Samko, Stefan; Wall, Peter (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      We study the p(.) -> q(.) boundedness of weighted multidimensional Hardy-type operators H-w(alpha(.)) and H-w(alpha(.)) of variable order alpha(x), with radial weight w(vertical bar x vertical bar), from a variable exponent locally generalized Morrey space L-p(.),L-phi(.)(R-n, w) to another L-q(.),L-psi(.)(R-n, w). The exponents are assumed to satisfy the decay condition at the origin and infinity. ...
    • Control of Spacecraft Formation with Disturbance Rejection and Exponential Gains 

      Schlanbusch, Rune; Kristiansen, Raymond (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      We address the problem of state feedback translational motion control of a spacecraft formation through a modified sliding surface controller using variable gains and I^2 action for disturbance rejection. The exponential varying gains ensure faster convergence of the state trajectories during attitude maneuver while keeping the gains small (and the system less stiff) for station keeping. Integral ...
    • Experimental study of relative permittivity of atmospheric ice 

      Bhattu, Shravan K; Mughal, Umair Najeeb; Virk, Muhammad Shakeel (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-01-01)
      Atmospheric icing on onshore and offshore structures is problematic, if we don’t detect and remove it. Despite of various ice detection techniques, capacitor based ice sensing technique is interesting one, as it is based on dielectric properties of material. This technique of measuring icing event is simple and cost- effective. Based on the dielectric concept, an experi mental ...
    • Atmospheric Icing Sensors - Capacitive Techniques 

      Mughal, Umair Najeeb; Virk, Muhammad Shakeel (Peer reviewed, 2013-01-22)
      The application of capacitive sensing technique is widely distributed in different physical domains primarily because of the diversity in dielectric permittivity and due to its minimum loading error and inertial effects. Atmospheric ice is a complex mixture of water, ice and air which is reflected in its complex dielectric constant. There are many existing atmospheric icing sensors but only few are ...
    • Numerical Study of Atmospheric Icing on Non Rotating Circular Cylinders in Tandem Arrangement 

      Virk, Muhammad Shakeel (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-03-01)
      Numerical study of atmospheric ice accretion on two non-rotating circular cylinders in tandem arrangement was carried out at different operating and geometric conditions. To validate the numerical model, initially the results of ice accretion on single circular cylinder were compared with the experimental data obtained from CIGELE atmospheric icing research wind tunnel (CAIRWT) [1, 2]. A good agreement ...
    • Deployment of a Neo-Hookean membrane: experimental and numerical analysis 

      Moatamedi, Mojtaba; Al-Bahkali, Essam; Erchiqui, Fouad; Souli, M (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-03-31)
      The aim of this research is to assess the response of a thin membrane subjected to high-pressure gas loading for inflation. This procedure is applied during the design process of the membrane structure to allow the product to resist high-pressure loading and to further characterize the hyper-elastic material. The simulation in this work considers the standard procedures used in the LS-DYNA software, ...
    • Optical water types of the Nordic Seas and adjacent areas 

      Aas, Eyvind; Højerslev, Niels Kristian; Høkedal, Jo; Sørensen, Kai (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-05-20)
      A new map of Jerlov's optical water types in the Nordic Seas and adjacent waters at 139 locations, as well as a table with statistical and geographical properties of the vertical attenuation coefficient of downward irradiance at 475 nm, are presented. The data analysis is based on 715 recordings at different stations, at latitudes between 54° and 82°N, and longitudes between 31°W and 49°E, obtained ...
    • Aerodynamic Modeling and Estimation of a Fixed-wing UAV 

      Andersen, Tom Stian (Master thesis; Mastergradsoppgave, 2013-06-20)
    • Modeling and simulation of space debris distribution 

      Bredeli, Thomas Iversen (Master thesis; Mastergradsoppgave, 2013-07-01)
    • Local refinement of ERBS curves 

      Dalmo, Rune (Journal article; Peer reviewed; Chapter, 2013-12-31)
      Expo-rational B-splines (ERBS) provide a blending type construction where local functions at each knot are blended together by infinitely smooth basis functions. In this work we consider some specific ERBS curves that are approximations of parametric curves. We study local refinement to increase flexibility by inserting local control curves at points of interest on the ERBS curve. Inserting knots ...
    • A green supply chain network design model for enhancing competitiveness and sustainability of companies in high north arctic regions 

      Yu, Hao; Solvang, Wei Deng; Chen, Chen (Peer reviewed, 2014)
      To survive in today's competitive and ever-changing marketplace, companies need not only to engage in their products and/or services, but also to focus on the management of the whole supply chain. Effectively managing and balancing the profitability and interconnection of each player in the supply chain will improve the overall supply chain surplus as well as individual profit. However, it is extremely ...
    • Science and Mathematics as part of practical projects in technology and design: An analysis of challenges in realising the curriculum in Norwegian schools 

      Bungum, Berit; Esjeholm, Bjørn-Tore; Lysne, Dag Atle (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
      Technology and design is seen by many as having a potential for students to work with science and mathematics in practical contexts. The view is particularly evident in the Norwegian curriculum, where technology and design is defined as an interdisciplinary topic involving Science, Mathematics and Art & Crafts. This paper reports from a video study of the use of mathematics and science in student ...
    • Design of water shock tube for testing shell materials 

      Ji, Hongjuan; Mustafa, Mohamad; Khawaja, Hassan Abbas; Ewan, Bruce C.; Moatamedi, Mojtaba (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-04-15)
      This paper presents design considerations for a shock tube experimental rig used to investigate the dynamic failure mechanisms of shell geometries subjected to water shock impact loading. In such setup, it is desirable that the drive pressure used within the tube can provide a wide range of impulsive loads on the test structures and some flexibility can be achieved on the applied pulse durations. ...
    • A field study of atmospheric icing analysis in a complex terrain of the high north 

      Rashid, Taimur; Mughal, Umair Najeeb; Mustafa, Mohamad; Virk, Muhammad Shakeel (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-12)
      Analyses of atmospheric icing events hold the key for computing the significant parameters leading to icing load calculations. In the cold regions of the high north, atmospheric icing loads on structures become important when it comes to design and safety of infrastructures. Furthermore, icing load calculations over a certain period of time provide a vital input for designers to improve the ...
    • Numerical investigation of vibration and dynamic pressure of a vertical axis wind turbine 

      Erchiqui, Fouad; Souli, M; Moatamedi, Mojtaba; Albahkali, E (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-12-31)
      In the environmental field, the problems of vibration reduction have become a major preoccupation, particularly on the noise generated by the acoustic radiation pressure produced by wind turbines. This paper is aimed at presenting the investigation on the application of FEM element method for study the acoustic radiation pressure produced by vertical-axis wind turbine. For this initiative, we ...
    • Using Mutual Charge Scheme to Measure Salinity of Ice 

      Mughal, Umair Najeeb; Nikumbh, Bhushan (Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
      For offshore measurements in Cold Regions, salinity of ice is also a critical parameter (together with many other parameterssuchasicingtype,load,icingrateandmeltingrate)to be identified in order to optimize the performance of anti/de icing systems. Although there are some available sensory solutions in the market to measure real time salinity levels of water, however there are still not many real ...
    • Matrix factorization of multivariate Bernstein polynomials 

      Dalmo, Rune (Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
      Ordinary univariate Bernstein polynomials can be represented in matrix form using factor matrices. In this paper we present the definition and basic properties of such factor matrices extended from the univariate case to the general case of arbitrary number of variables by using barycentric coordinates in the hyper-simplices of respective dimension. The main results in the paper are related to the ...
    • Shock Tube. Detail overview of equipment and instruments in the shock tube experimental setup 

      Khawaja, Hassan Abbas; Kapaya, Juma; Moatamedi, Mojtaba (Book; Bok, 2015)
      The shock tube is a device in which a normal shock wave is produced by the interaction of fluids at significantly high-pressure difference. The shock tube is comprised of two sections known as driver and driven sections. These two sections are interacted with the high-speed valve or a bursting disc. When the interaction happens, a shock wave forms almost instantaneously and propagates into the driven ...
    • Optimization of long-term performance of municipal solid waste management system: A bi-objective mathematical model 

      Yu, Hao; Solvang, Wei Deng; Li, Shiyun (Peer reviewed, 2015)
      Management of municipal solid waste has becoming an extremely important topic for any urban authorities in recent years due to the rapidly increasing solid waste quantity and potential environmental pollution. In this paper, a bi-objective dynamic linear programming model is developed for decision making and supporting in the long-term operation of municipal solid waste management system. The proposed ...
    • A note on the best constants in some hardy inequalities 

      Persson, Lars Erik; Samko, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
      Abstract. The sharp constants in Hardy type inequalities are known only in a few cases. In this paper we discuss some situations when such sharp constants are known, but also some new sharp constants are derived both in one-dimensional and multi-dimensional cases.