• Atmospheric ice monitoring system operation at Remote locations in cold region 

      Virk, Muhammad Shakeel; Rashid, Taimur; Mustafa, Mohamad Y (Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
      The problems encountered in installation, maintenance and operations of equipment in the cold climate regions are far more complicated than others. The contributing factors and problems that can affect the system operation and performance should be identified, assessed and focused within well-defined parameters before its installation in cold climate regions. The harsh cold environment, could not ...
    • Underactuated Waypoint Tracking of a Fixed-Wing UAV 

      Oland, Espen; Schlanbusch, Rune; Kristiansen, Raymond (Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
      In this paper a new method of performing waypoint tracking is shown for underactuated fixed-wing UAVs. The position error can be mapped onto the desired axis using a desired rotation matrix, while the velocity error can be mapped to the desired axis using a desired angular velocity. With all errors defined along one axis, the tracking problem is easily solved using only one thruster. A velocity ...
    • Underactuated Control of Quadrotors with Collision Avoidance 

      Oland, Espen; Andersen, Tom Stian; Kristiansen, Raymond (Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
      In this paper a saturated controller is derived that solves the translational control problem for underactuated quadrotors. The controller is applied to multiple quadrotors during a formation reconfiguration where the quadrotors move from an initial position to a desired position. The null-space-based behavioral control method is a popular method for avoiding collisions between mobile agents, and ...
    • Real-Time Particle Tracking using a Formation of UAVs 

      Oland, Espen; Kristiansen, Raymond (Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
      In this paper the problem of real-time particle tracking is studied. Using sensor measurements, a formation of UAVs autonomously find the closest point with high particle density where they enter a holding pattern. After converging to the holding pattern, one UAV will remain, while the rest will go looking for other maxima. To avoid collisions between the UAVs during the mission, a controller is ...
    • Ubemannede flaksende mikrofly 

      Oland, Espen (Journal article; Tidsskriftartikkel, 2013)
    • Weighted Hardy-Type Inequalities in Variable Exponent Morrey-Type Spaces 

      Lukkassen, Dag; Persson, Lars Erik; Samko, Stefan; Wall, Peter (Journal article; Peer reviewed; Tidsskriftartikkel, 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 ...
    • Simulation of Robotic Tasks with VALIP System - Practical Application 

      Malesevic, Nikola; Sziebig, Gábor; Solvang, Bjørn; Latinovic, Tihomir (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      In manufacturing engineering, man-machine interaction has gone from typical online programming techniques into virtual reality based offline programming methodologies. Today, a wide range of offline software tools is used to imitate, simulate and control real manufacturing systems. However, these new methodologies lack capability when it comes to human-machine communication. This paper aims to ...
    • Experimental study of relative permittivity of atmospheric ice 

      Bhattu, Shravan K; Mughal, Umair Najeeb; Virk, Muhammad Shakeel (Journal article; Peer reviewed; Tidsskriftartikkel, 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; Journal article; Tidsskriftsartikkel, 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)
    • Some new iterated Hardy-type inequalities: the case theta=1 

      Gogatishvili, Amiran; Mustafayev, Rza; Persson, Lars Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-11-08)
      In this paper we characterize the validity of the Hardy-type inequality &#8741 &#8741 &#8747 <sub>s</sub>&#8734) h(z)dz &#8741 p,u,(0,t) &#8741 q,w,(=,&#8734≤ c&#8741h&#8741 1,v(0,&#8734) where 0 < p < ∞,0< q ≤ +∞, u, w and v are weight functions on (0,∞). It is pointed out that this characterization can be used to obtain new characterizations for the boundedness between weighted Lebesgue spaces ...
    • 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 ...
    • 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; Peer reviewed; Tidsskriftartikkel, 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 ...
    • 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; Journal article; Tidsskriftsartikkel, 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 ...
    • 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. ...