Hind Taud

DEM generation by contour line dilation

Abstract A method is developed to generate digital elevation models by means of the dilation of contour lines stored in a raster grid. An iterative procedure produces an extension of contour lines by applying alternative four-connected and eight-connected erosions of the background until the produced surfaces become contiguous. The limits between these surfaces correspond to a new family of intermediate contour lines that are added to the raster grid. This procedure stops when no new contour lines can be generated. C subroutines are given. The algorithm is simple to apply and has a low computational cost.

A new kinematic approach for the Danakil block using a Digital Elevation Model representation

Abstract Data from the literature are integrated in a regional Digital Elevation Model (DEM) in order to analyse the motion of the Danakil block with regard to the Arabian and Somalian plates. The application of the poles and angles of rotation taken from the literature, induces a superposition of the Danakil block on the Arabian plate, and the formation of a gap in the Afar region. The determination of new poles of rotation using a best-fitting procedure allows one to avoid these drawbacks. In all cases, calculations are carried out keeping the Nubian plate stationary. The present approach shows that the Danakil block is an independent entity and is not related to the Nubian and Arabian plates. Between the Oligocene and the Miocene, it has been submitted to a N20°E sinistral strike-slip motion anterior to the rotation itself that was started in the middle Miocene. This rotation is directed by a mechanical couple due to the combination of the Red Sea and North Afar extensions.

Detection of circular structures on satellite images

Abstract An unsupervised method is proposed for detecting circular structures on satellite images partly based on a version of the Hough Transform. This method consists of two major steps: the extraction of significant contours from the image, using mathematical morphology operators, and the detection of circular structures from the contours previously denned. The latter includes four substeps: individualization of the curves, decomposition of the curves into near-circular elements, application of the ‘adaptive HT’ version to each near-circular element, and computation of more precise results. As an example, the method is applied to a SPOT scene in Southern Peru to detect geological structures.

Orientation of absolute African plate motion revealed by tomomorphometric analysis of the Ethiopian dome

The Ethiopian dome, comprising the Ethiopian and Yemeni Plateaus, formed as a result of the uplift of Red Sea, Gulf of Aden, and Ethiopian rift shoulders; the uplift was essentially due to a mantle-plume activity. A digital elevation model of this region before rifting, constructed by using the rotation of its constituent plates and pulling down the rift shoulders, reveals that important high areas existed before rifting. These highs are interpreted to be the result of mantle plume activity. A fast Fourier transform was used to smooth the digital elevation model prerift dome before a tomomorphometric analysis was applied to quantify the orientation of each digital elevation model horizontal slice. This procedure allowed us to determine a bearing of N30°E for absolute African plate motion since the Paleogene.

Detection and classification of circular structures on SPOT images

An unsupervised method for detecting structural features on satellite images that consists of three major steps is proposed. The extraction of contours, which depends on the texture encountered is achieved by an iterative filtering followed by several thresholds that generate binary images. The detection of the structures from the contours involves four substeps: individualization of the curves; decomposition of the curves into subcircular elements; application of a version of the Hough transform to each subcircular element; and computation of precise results. The parameters that discriminate the structures are computed. These data allow the selection of different families of structures that are being looked at. The method has been applied to the region of Azru. >

A Micro Artificial Immune System

In this paper, we present a new algorithm, namely, a micro artificial immune system (Micro-AIS) based on the Clonal Selection Theory for solving numerical optimization problems. For our study, we consider the algorithm CLONALG, a widely used artificial immune system. During the process of cloning, CLONALG greatly increases the size of its population. We propose a version with reduced population. Our hypothesis is that reducing the number of individuals in a population will decrease the number of evaluations of the objective function, increasing the speed of convergence and reducing the use of data memory. Our proposal uses a population of 5 individuals (antibodies), from which only 15 clones are obtained. In the maturation stage of the clones, two simple and fast mutation operators are used in a nominal convergence that works together with a reinitialization process to preserve the diversity. To validate our algorithm, we use a set of test functions taken from the specialized literature to compare our approach with the standard version of CLONALG. The same method can be applied in many other problems, for example, in text processing.

Modeling and Simulation for a DC/DC Buck Power Electronic Converter -- DC Motor System

In order to drive both positive and negative directions in the shaft of a DC motor connected to a DC/DC Buck power electronic converter, this paper presents a new topology of the DC/DC Buck power electronic converter-DC motor system. To this end, a full-bridge converter is placed between the Buck converter and the DC motor. The deduction of the mathematical model step-by-step, from applying Kirchhoffs voltage and current laws is shown. Later, an analysis in steady-state is presented, obtaining the system equilibrium point. Finally, numerical simulations are performed through Matlab-Simulink, showing the viability of our proposal.

Tracking Control for Mobile Robots Considering the Dynamics of All Their Subsystems: Experimental Implementation

The trajectory tracking task in a wheeled mobile robot (WMR) is solved by proposing a three-level hierarchical controller that considers the mathematical model of the mechanical structure (differential drive WMR), actuators (DC motors), and power stage (DC/DC Buck power converters). The highest hierarchical level is a kinematic control for the mechanical structure; the medium level includes two controllers based on differential flatness for the actuators; and the lowest hierarchical level consists of two average controllers also based on differential flatness for the power stage. In order to experimentally validate the feasibility of the proposed control scheme, the hierarchical controller is implemented via a – -modulator in a differential drive WMR prototype that we have built. Such an implementation is achieved by using MATLAB-Simulink and the real-time interface ControlDesk together with a DS1104 board. The experimental results show the effectiveness and robustness of the proposed control scheme.

Simulation, construction, and validation of a DC/DC buck power converter-DC motor system

This paper presents the simulation, construction, and validation of a new topology of a DC/DC Buck power converter-DC motor system. The main objective is to achieve forwards and backwards rotation on the DC motor shaft. For this purpose a full-bridge converter is installed between the DC/DC Buck power converter and the DC motor. Also, as a result of applying Kirchhoffs current and voltage laws and Newtons second law of motion, the mathematical model of the system under study is shown. As well, a detailed analysis in steady-state is presented, thus obtaining the system equilibrium point. Furthermore, numerical simulations are performed via Matlab-Simulink. Finally, with the intention of verifying and validating the behavior of the mathematical model presented herein, experimental tests are carried out by means of Matlab-Simulink, ControlDesk, and DS1104 board from dSPACE. Thus, simulation and experimental results are used to confirm the validity of our proposal.

Modeling and Construction of an Inertia Wheel Pendulum Test-Bed

This paper presents the detailed deduction of an inertia wheel pendulum (IWP) mathematical model, through the Lagrange equations of motion. Also, a mechanical design and the construction of the IWP are introduced step by step. This with the purpose of providing a material that can be useful in the easy comprehension of an IWP mathematical model and to accomplish the construction of an IWP in a relatively short time. The mechanical design is carried out by using the software Solid Works. Moreover, numerical simulations of the deduced mathematical model are performed via Mat lab-Simulink. Furthermore, in order to verify that the IWP built behaves according to the mathematical model herein deduced, experimental tests are carried out by using such an IWP, Mat lab-Simulink, Control Desk, and a DS1104 board from d SPACE.