Now showing items 1-10 of 37
Regression analysis using a blending type spline construction
(Peer reviewed; Bokkapittel; Chapter, 2017-10-18)
Regression analysis allows us to track the dynamics of change in measured data and to investigate their properties. A sufficiently good model allows us to predict the behavior of dependent variables with higher accuracy, and to propose a more precise data generation hypothesis. By using polynomial approximation for big data sets with complex dependencies we get piecewise smooth functions. One way ...
Thyristor based short circuit current injection in isolated grids
(Peer reviewed; Bokkapittel; Chapter, 2017-02-16)
This paper proposes a thyristor based short circuit current injector for providing short circuit current in isolated and weak grids, where sufficient fault current to trigger circuit breakers may not be available. This will allow the use of conventional miniature circuit breakers, which requires high fault current for instantaneous tripping. The method has been validated through experiments.
A decision-support model for operational planning of surface coal mining considering equipment failure
(Peer reviewed; Bokkapittel; Conference object; Konferansebidrag; Chapter, 2016)
This paper presents a decision-support model aiming, primarily, at maximizing the productivity of surface coal mining activities through operational planning and management. The model is formulated based upon mixed integer programming, and it determines the optimal production plan of the shovels and allocation plan of the haul trucks in order to minimize operational cost, fuel consumption as well ...
A Trade-off Model for Green Supply Chain Design: An Efficiency-versus-Emission Analysis
(Peer reviewed; Bokkapittel; Chapter, 2018-04-09)
—With the growing concern of climate change and global warming, the reduction on carbon emissions of supply chain activities have been increasingly focused by both academics and corporates in the last two decades. The increased public awareness on sustainability and stricter environmental policies together enforce the companies to rethink their practices in supply chain design and operations in an ...
Quaternion guidance and control of quadrotor
(Peer reviewed; Bokkapittel; Conference object; Konferansebidrag; Chapter, 2017-07-27)
This paper addresses the problem of trajectory tracking for underactuated quadrotors. A quaternion based guidance law is proposed which feeds into an attitude control system based on a PD+ control law. The desired attitude from the guidance law is defined such that the attitude control system tries to align the position error along the axis of the translational actuator. Simulation results are ...
Path-following in three dimensions using quaternions for a fixed-wing UAV
(Peer reviewed; Konferansebidrag; Bokkapittel; Conference object; Chapter, 2017-08-08)
This paper presents a three dimensional guidance strategy for fixed-wing UAVs using quaternions. The algorithm is based on constructing two quaternions, one which makes the UAV fly towards the path and one that makes the UAV follow the path. These two quaternions are then blended together such that the path-following objective is reached. The guidance algorithm is applied to a simple kinematic model ...
Approaches to learning of linear algebra among engineering students
(Peer reviewed; Bokkapittel; Bok; Book; Chapter, 2017-02)
The present paper investigates engineering students` own descriptions of what they mean by learning of linear algebra and how they know that they have learned something. I seek to extract keywords from engineering students` descriptions of learning of this discipline by drawing on grounded theory techniques and classifying the answers in conceptual and procedural approaches. By this, both detailed ...
Improving the Decision-making of Reverse Logistics Network Design Part II: An Improved Scenario-based Solution Method and Numerical Experimentation
(Peer reviewed; Chapter; Bokkapittel, 2018-02-11)
The study of the network design problems related to reverse supply chain and reverse logistics is of great interest for both academicians and practitioners due to its important role for a sustainable society. However, reverse logistics network design is a complex decision-making problem that involves several interactive factors and faces many uncertainties. Thus, in order to improve the reverse ...
Attitude Determination and Control System for Satellites in Elliptical Orbits - a Complete Solution
(Peer reviewed; Conference object; Konferansebidrag; Bokkapittel; Chapter, 2017-08-08)
This paper presents a complete solution to the problem of attitude determination and control for satellites in elliptical orbits. Specifically, it shows how to create the orbital mechanics, account for perturbing gravity torques, create a nonlinear PD+ attitude controller, map the control signal to desired thrust firings, implement magnetic field and Sun vector models, and how to implement a Madgwick ...
Autonomous Inspection of the International Space Station
(Peer reviewed; Bokkapittel; Konferansebidrag; Conference object; Chapter, 2017-09-18)
This paper presents a solution to autonomous inspection of the international space station using a rigid spacecraft. Specifically, the paper presents the orbital mechanics, formation dynamics as well as rotational dynamics required to control the spacecraft relative to the space station, and then presents two PD+ controllers enabling a spacecraft to track a series of waypoints while pointing a sensor ...