Den här rapporten beskriver och behandlar resultatet av ett kandidatarbete som utfördes i kursen TDDD96:Kandidatprojekt i programvaruutveckling som ges vid Linköpings universitet. Namnet på projektet som har utförts är Drone Light Display och det beställdes av RISE Research Institutes of Sweden AB. Den division av RISE som har lokaler på Linköpings universitet är inriktade på drönarforskning. Uppdraget blev därför att skapa en algoritm för att detektera och undvika kollision mellan drönare samt implementera ett omkringliggande system för att generera ljusshower med hjälp av drönare som flyger i formation. Projektet utfördes av sju tredjeårsstudenter som studerar till Civilingenjör i data- respektive mjukvaruteknik vid Linköpings universitet. Det resulterade i två användargränssnitt, ett för hantering av ljusshower och ett för statuskontroll av drönare, två servrar och en antikollisionsmodul. Antikollisionsmodulen körs som en separat process på varje drönare och är kompatibel med RISE:s egna styrsystem, Drone Safety Service. De båda servrarna tar emot en rad information från drönarna och sammanställer och skickar sedan ut denna till alla drönare och antikollisionsmodulen. På så sätt får antikollisionsmodulen tillgång till den information som behövs för att kunna ta informerade beslut så att drönarna kan undvika kollisioner. Avslutningsvis innehåller rapporten individuella bidrag från varje projektmedlem inom diverse ämnen som är kopplade till mjukvaruutveckling eller till projektet i allmänhet.

This thesis work aims at performing a survey of those technologies generally called DriverAssistance Systems (DAS). This thesis work focuses on gathering information in terms ofaccident statistics, sensors and functions and analyzing this information and shall thruaccessible information match functions with accidents, functions with sensors etc.This analysis, based on accidents in United States and Sweden during the period 1998 – 2002and two truck accident studies, shows that of all accidents with fatalities or sever injuriesinvolving a heavy truck almost half are the result of a frontal impact. About one fourth of theaccidents are caused by side impact, whereas single vehicle and rear impact collisions causesaround 14 % each. Of these, about one fourth is collision with unprotected (motorcycles,mopeds, bicycles, and pedestrians) whereas around 60 % are collision with other vehicles.More than 90 % of all accidents are partly the result of driver error and about 75 % aredirectly the result of driver error. Hence there exist a great opportunity to reduce the numberof accidents by introducing DAS.In this work, an analysis of DAS shows that six of the systems discussed today have thepotential to prevent 40 – 50 % of these accidents, whereas 20 – 40 % are estimated to actuallyhaving the chance to be prevented.One of these DAS, automatic emergency brake (AEB), has been analyzed in more detail.Decision models for an emergency brake capable to mitigate rear-end accidents has beendesigned and evaluated. The results show that this model has high capabilities to mitigatecollisions.

Les algorithmes cryptographiques actuels se répartissent en deux grandes familles : les algorithmes symétriques et les algorithmes asymétriques. En 1991, S. Even et Y. Mansour ont proposé une construction simple d'un algorithme de chiffrement par blocs en utilisant une permutation aléatoire. Récemment, surtout pour répondre aux nouveaux enjeux de la cryptographie à bas coût, plusieurs algorithmes ont été proposés dont la construction est basée sur le schéma Even-Mansour. Les travaux réalisés dans cette thèse ont pour objet l'analyse de ce type d'algorithmes. À cette fin, nous proposons une nouvelle attaque générique sur le schéma Even-Mansour. Ensuite, afin de montrer l'importance particulière du modèle multi-utilisateurs, nous appliquons cette attaque générique dans ce modèle. Ces deux attaques sur Even-Mansour introduisent deux nouvelles idées algorithmiques : les chaînes parallèles et la construction d'un graphe qui illustre les liens entre les clés des utilisateurs du modèle multi-utilisateurs. Finalement, basés sur ces idées, nous proposons des attaques sur les algorithmes de chiffrement par blocs DESX et PRINCE et sur le code d'authentification de message Chaskey. / Current cryptographic algorithms are divided into two families: secret-key algorithms (or symmetric algorithms) and public-key algorithms. Secret-key cryptography is characterized by the sharing of the same key K used by both legitimate users of the cryptosystem. Bloc ciphers are one of the main primitives of symmetric cryptography. In 1991, S. Even and Y. Mansour proposed a minimal construction of a bloc cipher which uses a random permutation. Recently, in the context of lightweight cryptography, many algorithms based on the Even-Mansour scheme have been proposed. In this thesis, we focus on the analysis of this type of algorithms. To this purpose, we propose a generic attack on the Even-Mansour scheme. To show the particular importance of the multi-user model, we adapt our attack to this context. With these attacks, we introduce two new algorithmic ideas: the parallel chains and the construction of graph which represents the relations between the keys of the users of the multi-user model. Finally, we use these ideas and we present attacks on the bloc ciphers DESX and PRINCE and on the message authentication code (MAC) Chaskey.

Cette thèse porte sur des techniques de commande à base d’optimisation dans le cadre des systèmes dynamiques Multi-Agents sous contraintes, plus particulièrement liées à l’évitement des collisions. Dans un contexte ensembliste, l’évitement des collisions au sein de la formation se traduit par des conditions de non intersection des régions de sécurité caractéristiques à chaque agent/obstacle. Grace à sa capacité à gérer les contraintes, la commande prédictive a été choisie parmi les méthodes de synthèse fondées sur des techniques d’optimisation. Tout d’abord, une structure de type leader-suiveur est considérée comme une architecture décentralisée élémentaire. La zone de fonctionnement de chaque suiveur est décidée par le leader et puis une loi de commande locale est calculée afin de garantir que les suiveurs restent à l’intérieur de la zone autorisée, permettant d’éviter les collisions. Ensuite, un déploiement des agents fondé sur l’approche de commande prédictive décentralisée, utilisant des partitions dynamiques de Voronoi, est proposé, permettant de ramener chaque agent vers l’intérieur de sa cellule Voronoi. Une des contributions a été de considérer le centre de Chebyshev comme cible à l’intérieur de chaque cellule. D’autres solutions proposent l’utilisation du centre de masse ou du centre obtenu par l’interpolation des sommets. Finalement, des méthodes ensemblistes sont utilisées pour construire un niveau supplémentaire de détection de défauts dans le cadre du système Multi-Agents. Cela permet l’exclusion des agents défectueux ainsi que l’intégration des agents extérieurs certifiés sans défauts dans la formation en utilisant des techniques de commande prédictive centralisée. / This thesis presents optimizationbased control techniques for dynamical Multi-Agent systems (MAS) subject to collision avoidance constraints. From the set-theoretic point of view, collision avoidance objective can be translated into non-overlapping conditions for the safety regions characterizing each agent/obstacle while maintaining the convergence towards a specified formation. Among the successful optimizationbased control methods, Model Predictive Control (MPC) is used for constraints handling. First, a leader-follower structure is considered as a basic decentralized architecture. The followers functioning zone assignment is decided by the leader and then the local linear feedback control is computed such that the follower operates strictly inside its authorized zone, offering anti-collision guarantees. Second, a dynamic Voronoi partition based deployment of the agents using an inner target driver is developed. The main novelty is to consider the Chebyshev center as the inner target for each agent, leading to an optimization-based decentralized predictive control design. In the same topic, other inner targets are considered such as the center of mass or vertex interpolated center. Third, set-theoretic tools are used to design a centralized FDI layer for dynamical MAS, leading to the exclusion of a faulty agent from the MAS formation and the integration of an external healthy/recovered agent in the current formation. The set-based FDI allows detecting and isolating these faulty agents to protect the current formation using centralized predictive control techniques.

In this thesis, central configurations, regularization of Simultaneous binary collision, linear stability of Kepler orbits, and index theory for symplectic path are studied. The history of their study is summarized in section 1. Section 2 deals with the following problem: given a collinear configuration of 4 bodies, under what conditions is it possible to choose positive masses which make it central. It is always possible to choose three positive masses such that the given three positions with the masses form a central configuration. However, for an arbitrary configuration of 4 bodies, it is not always possible to find positive masses forming a central configuration. An expression of four masses is established depending on the position x and the center of mass u, which gives a central configuration in the collinear four body problem. Specifically it is proved that there is a compact region in which no central configuration is possible for positive masses. Conversely, for any configuration in the complement of the compact region, it is always possible to choose positive masses to make the configuration central. The singularities of simultaneous binary collisions in collinear four-body problem is regularized by explicitly constructing new coordinates and time transformation in section 3. The motion in the new coordinates and time scale across simultaneous binary collision is at least C^2. Furthermore, the behavior of the motion closing, across and after the simultaneous binary collision, is also studied. Many different types of periodic solutions involving single binary collisions and simultaneous binary collisions are constructed. In section 4, the linear stability is studied for the Kepler orbits of the rhombus four-body problem. We show that, for given four proper masses, there exists a family of periodic solutions for which each body with the proper mass is at the vertex of a rhombus and travels along an elliptic Kepler orbit. Instead of studying the 8 degrees of freedom Hamilton system for planar four-body problem, we reduce this number by means of some symmetry to derive a two degrees of freedom system which then can be used to determine the linear instability of the periodic solutions. After making a clever change of coordinates, a two dimensional ordinary differential equation system is obtained, which governs the linear instability of the periodic solutions. The system is surprisingly simple and depends only on the length of the sides of the rhombus and the eccentricity e of the Kepler orbit. In section 5, index theory for symplectic paths introduced by Y.Long is applied to study the stability of a periodic solution x for a Hamiltonian system. We establish a necessary and sufficient condition for stability of the periodic solution x in two and four dimension.

This work introduces the notion of computational hypertime, or the simulation and visualization of hypothetical environments possessing multidimensional time. An overview of hypertime is provided,including an intuitive visualization paradigm and a discussion of the failure of common simulation techniques when extended to include multidimensional time. A condition for differential equations describing hypertime motion to be amenable to standard time-iterative simulation techniques is provided,but is not satisfied by any known model of physics. An alternate simulation algorithm involving iterative refinement of entire equations of motion is presented,with an example implementation to solve elastic collisions in hypertime. An artificial intelligence algorithm for navigating crowds in any arbitrary nD/mT environment is discussed,and an implementation is provided using collision cones and stochastic global optimization techniques. Possible models of hypertime energy and other open questions are discussed. Both algorithms are described and show favorable results, meeting all design criteria and running at interactive speeds on common desktop computer systems.

No description available.

Particulate systems in practical applications such as biomass combustion, blood cellular systems and granular particles in fluidized beds, have often been computationally represented using spherical surfaces, even though the majority of particles in archetypal fluid-solid systems are non-spherical. While spherical particles are more cost-effective to simulate, notable deficiencies of these implementations are their substantial inaccuracies in predicting the dynamics of particle mixtures. Alternatively, modeling dense fluid-particulate systems using non-spherical particles involves increased complexity, with computational cost manifesting as the biggest bottleneck. However, with recent advancements in computer hardware, simulations of three-dimensional particulate systems using irregular shaped particles have garnered significant interest. In this research, a novel Discrete Element Method (DEM) model that incorporates geometry definition, collision detection, and post-collision kinematics has been developed to accurately simulate non-spherical particulate systems. Superellipsoids, which account for 80% of particles commonly found in nature, are used to represent non-spherical shapes. Collisions between these particles are processed using a distance function computation carried out with respect to their surfaces. An event - driven model and a time-driven model have been employed in the current framework to resolve collisions. The collision model's influence on non–spherical particle dynamics is verified by observing the conservation of momentum and total kinetic energy. Furthermore, the non-spherical DEM model is coupled with an in-house fluid flow solver (GenIDLEST). The combined CFD-DEM model's results are validated by comparing to experimental measurements in a fluidized bed. The parallel scalability of the non-spherical DEM model is evaluated in terms of its efficiency and speedup. Major factors affecting wall clock time of simulations are analyzed and an estimate of the model's dependency on these factors is documented. The developed framework allows for a wide range of particle geometries to be simulated in GenIDLEST. / Master of Science / CFD – DEM (Discrete Element Method) is a technique of coupling fluid flow solvers with granular solid particles. CFD – DEM simulations are beneficial in recreating pragmatic applications such as blood cellular flows, fluidized beds and pharmaceutics. Up until recently, particles in these flows have been modeled as spheres as the generation of particle geometry and collision detection algorithms are straightforward. However, in real – life occurrences, most particles are irregular in shape, and approximating them as spheres in computational works leads to a substantial loss of accuracy. On the other hand, non – spherical particles are more complex to generate. When these particles are in motion, they collide and exhibit complex trajectories. Majority of the wall clock time is spent in resolving collisions between these non – spherical particles. Hence, generic algorithms to detect and resolve collisions have to be incorporated. This primary focus of this research work is to develop collision detection and resolution algorithms for non – spherical particles. Collisions are detected using inherent geometrical properties of the class of particles used. Two popular models (event-driven and time-driven) are implemented and utilized to update the trajectories of particles. These models are coupled with an in – house fluid solver (GenIDLEST) and the functioning of the DEM model is validated with experimental results from previous research works. Also, since the computational effort required is higher in the case of non – spherical particulate simulations, an estimate of the scalability of the problem and factors influencing time to simulations are presented.

Denna studie genomfördes med syftet att undersöka yrkessjöfartens grundstötningar och kollisioner inom svenska hamnområden. Studien genomfördes som en kvantitativt inriktad systematisk litteraturstudie. I denna studies metod delades inträffade olyckor in i tre kategorier: fartyg med lots, fartyg med lotsdispens och fartyg utan lotsplikt. Rapporter om olyckor som inträffat mellan 2003 och 2013 inom svenska hamnområden utgjorde studiens underlag av data. Resultaten visar att fartyg utan lotsplikt är involverade i fler grundstötningar och kollisioner inom svenska hamnområden än fartyg med lotsplikt. Resultaten visar även att fartyg utan lotsplikt kolliderar med andra fartyg i högre utsträckning än vad fartyg med lotsplikt gör och att fartyg som navigerar med lotsdispens är något mer riskbenägna under sämre vind- och siktförhållanden. / The following study was conducted with the intent of reviewing groundings and collisions within Swedish port facilities involving commercially operated vessels. The method used was a quantitative systematic literature review. The study compared accidents involving vessels with pilot onboard and vessels which were exempted pilotage. Reports of accidents occurring between 2003 and 2013 were the study’s basis of data. The results show that the vast majority of accidents involved vessels exempted from pilotage due to ships’ particulars. The most common type of accidents involving the aforementioned vessels were collisions with other vessels, which stands in clear contrast to the other two vessel categories which both mostly tended to collide with fixed objects. In summary, this study clearly demonstrates that vessels whose particulars make them exempted from pilotage are at greatly increased risk of being involved in groundings and collision within port facilities.

Denna studie genomfördes med syftet att undersöka yrkessjöfartens grundstötningar och kollisioner inom svenska hamnområden. Studien genomfördes som en kvantitativt inriktad systematisk litteraturstudie. I denna studies metod delades inträffade olyckor in i tre kategorier: fartyg med lots, fartyg med lotsdispens och fartyg utan lotsplikt. Rapporter om olyckor som inträffat mellan 2003 och 2013 inom svenska hamnområden utgjorde studiens underlag av data. Resultaten visar att fartyg utan lotsplikt är involverade i fler grundstötningar och kollisioner inom svenska hamnområden än fartyg med lotsplikt. Resultaten visar även att fartyg utan lotsplikt kolliderar med andra fartyg i högre utsträckning än vad fartyg med lotsplikt gör och att fartyg som navigerar med lotsdispens är något mer riskbenägna under sämre vind- och siktförhållanden. / The following study was conducted with the intent of reviewing groundings and collisions within Swedish port facilities involving commercially operated vessels. The method used was a quantitative systematic literature review. The study compared accidents involving vessels with pilot onboard and vessels which were exempted pilotage. Reports of accidents occurring between 2003 and 2013 were the study’s basis of data. The results show that the vast majority of accidents involved vessels exempted from pilotage due to ships’ particulars. The most common type of accidents involving the aforementioned vessels were collisions with other vessels, which stands in clear contrast to the other two vessel categories which both mostly tended to collide with fixed objects. In summary, this study clearly demonstrates that vessels whose particulars make them exempted from pilotage are at greatly increased risk of being involved in groundings and collision within port facilities.Keywords:Pilotage, Pilot,