Integration of Corona and Landsat Thematic Mapper data for bedrock geological studies in the high Arctic

The Severnaya Zemlya Archipelago near the continental edge in the Russian high Arctic is one of few land areas along the Eurasian Arctic margin. It is of particular interest for investigating the Arctic's tectonic history. This study focuses on the Palaeozoic bedrock of October Revolution Island. In the Russian high Arctic detailed topographic maps and aerial photography often are not available. The potential of low-cost satellite imagery as a substitute is shown in this study. High-resolution Corona KH-4A panchromatic satellite imagery and Landsat Thematic Mapper (TM) multispectral data have been integrated. In combination with field investigations in key areas, these data provide the basis for new interpretations of the geology. Corona images were digitized and georeferenced to provide a basis for conventional and digital geological mapping. Merging Corona and Landsat TM data resulted in a high-resolution multispectral image of enhanced interpretability. Lithological contacts have been traced, supported by a bedrock image extracted from the Landsat TM data. Stereoscopic coverage of the Corona KH-4A photographic sensor allowed a structural interpretation. All results were integrated into a geological interpretation of southern October Revolution Island which provides an encouraging platform for further work in the high Arctic.     

Image Sequence Interpolation Using Optimal Control

The problem of finding an interpolating image between two given images in an image sequence is considered. The problem is formulated as an optimal control problem governed by a transport equation, i.e. we aim at finding a flow field which transports the first image as close as possible to the second image. This approach bears similarities with the Horn and Schunck method for optical flow calculation but in fact the model is quite different. The images are modeled in the space of functions of bounded variation and an analysis of solutions of transport equations in this space is included. Moreover, the existence of optimal controls is proven and necessary conditions are derived. Finally, two algorithms are given and numerical results are compared with existing methods. The new method is competitive with state-of-the-art methods and even outperforms several existing methods.     

Three 2D-warping schemes for visual robot navigation

Warping (Franz et al., Biological Cybernetics 79(3), 191–202, 1998b) and 2D-warping (Möller, Robotics and Autonomous Systems 57(1), 87–101, 2009) are effective visual homing methods which can be applied for navigation in topological maps. This paper presents several improvements of 2D-warping and introduces two novel “free” warping methods in the same framework. The free warping methods partially lift the assumption of the original warping method that all landmarks have the same distance from the goal location. Experiments on image databases confirm the effect of the improvements of 2D-warping and show that the two free warping methods produce more precise home vectors and approximately the same proportion of erroneous home vectors. In addition, two novel and easier-to-interpret performance measures for the angular error are introduced.     

High-pressure,laser-driven deformation of an aluminum alloy

Recent development of a laser-based experimental platform allows loading materials to high pressures in the solid state while controlling both strain rate and peak pressure. The drive utilizes momentum transfer from a plasma generated by the introduction of a strong shock in a reservoir of low-Z material. This study looks at the response of a commercial aluminum alloy (6061-T6) subjected to pressures of 18 and 40 GPa at strain rates of 10⁷/s and 5 × 10⁷/s, respectively. It was found that the depth of the crater formed on the sample surface is a good indicator of the general yield behavior of the material and that a relatively simple strength model prevails under the loading conditions considered here. Metallographic examination of recovered samples showed no evidence of shear-band formation or significant melting due to plasma-surface interactions. Crystal plasticity-based calculations were used to assess the effects of material texture. Lack of shear-band formation during the laser-based drive is rationalized by considering the strain gradient as compared to grain size and texture. This article is based on a presentation given in the symposium “Dynamic Deformation: Constitutive Modeling, Grain Size, and Other Effects: In Honor of Prof. Ronald W. Armstrong,” March 2–6, 2003, at the 2003 TMS/ASM Annual Meeting, San Diego, California, under the auspices of the TMS/ASM Joint Mechanical Behavior of Materials Committee.     

Neutron diffraction study of texture development during hot working of different gamma-titanium aluminide alloys

The evolution of preferred orientations during processing appears to be of significant importance for the use of γ-titanium aluminide alloys, since the desired lamellar microstructures exhibit a strong anisotropy of mechanical properties. In this work, texture development has been investigated after hot extrusion and sheet rolling, which are considered to be technologically relevant wrought processes. As texture evolution certainly is dependent on several factors, involving deformation properties, recrystallization kinetics, and, particularly, the phase constitution at hot-working temperature, different processing conditions and alloy compositions were investigated. By comparing the results, it is indicated that the determined textures can be understood by the deformation modes of the dominating phase at hot-working temperature and the subsequent phase transformations. However, the current understanding of texture evolution is far from being complete, as no model can be presented which quantitatively accounts for the contribution of the different processes mentioned.     

Stator- and rotor-flux-based deadbeat direct torque control of induction machines

A new deadbeat type of direct torque control (DTC) is proposed, analyzed, and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position- and speed-sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low-speed operation. The paper first develops the new deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.     

Quadratic programming algorithms for large-scale model predictive control

Quadratic programming (QP) methods are an important element in the application of model predictive control (MPC). As larger and more challenging MPC applications are considered, more attention needs to be focused on the construction and tailoring of efficient QP algorithms. In this study, we tailor and apply a new QP method, called QPSchur, to large MPC applications, such as cross directional control problems in paper machines. Written in C++, QPSchur is an object oriented implementation of a novel dual space, Schur complement algorithm. We compare this approach to three widely applied QP algorithms and show that QPSchur is significantly more efficient (up to two orders of magnitude) than the other algorithms. In addition, detailed simulations are considered that demonstrate the importance of the flexible, object oriented construction of QPSchur, along with additional features for constraint handling, warm starts and partial solution.     

Correction to: Using I2P (Invisible Internet Protocol) Encrypted Virtual Tunnels for a Secure and Anonymous Communication in VANets: I2P Vehicular Protocol (IVP)

Wireless Personal Communications -