Decision-making and problem-solving methods in automation technology

The state of the art in the automation of decision making and problem solving is reviewed. The information upon which the report is based was derived from literature searches, visits to university and government laboratories performing basic research in the area, and a 1980 Langley Research Center sponsored conferences on the subject. It is the contention of the authors that the technology in this area is being generated by research primarily in the three disciplines of Artificial Intelligence, Control Theory, and Operations Research. Under the assumption that the state of the art in decision making and problem solving is reflected in the problems being solved, specific problems and methods of their solution are often discussed to elucidate particular aspects of the subject. Synopses of the following major topic areas comprise most of the report: (1) detection and recognition; (2) planning; and scheduling; (3) learning; (4) theorem proving; (5) distributed systems; (6) knowledge bases; (7) search; (8) heuristics; and (9) evolutionary programming

Intelligent Data Mining using Kernel Functions and Information Criteria

Radial Basis Function (RBF) Neural Networks and Support Vector Machines (SVM) are two powerful kernel related intelligent data mining techniques. The current major problems with these methods are over-fitting and the existence of too many free parameters. The way to select the parameters can directly affect the generalization performance(test error) of theses models. Current practice in how to choose the model parameters is an art, rather than a science in this research area. Often, some parameters are predetermined, or randomly chosen. Other parameters are selected through repeated experiments that are time consuming, costly, and computationally very intensive. In this dissertation, we provide a two-stage analytical hybrid-training algorithm by building a bridge among regression tree, EM algorithm, and Radial Basis Function Neural Networks together. Information Complexity (ICOMP) criterion of Bozdogan along with other information based criteria are introduced and applied to control the model complexity, and to decide the optimal number of kernel functions. In the first stage of the hybrid, regression tree and EM algorithm are used to determine the kernel function parameters. In the second stage of the hybrid, the weights (coefficients) are calculated and information criteria are scored. Kernel Principal Component Analysis (KPCA) using EM algorithm for feature selection and data preprocessing is also introduced and studied. Adaptive Support Vector Machines (ASVM) and some efficient algorithms are given to deal with massive data sets in support vector classifications. Versatility and efficiency of the new proposed approaches are studied on real data sets and via Monte Carlo sim- ulation experiments

SOLID-SHELL FINITE ELEMENT MODELS FOR EXPLICIT SIMULATIONS OF CRACK PROPAGATION IN THIN STRUCTURES

Crack propagation in thin shell structures due to cutting is conveniently simulated using explicit finite element approaches, in view of the high nonlinearity of the problem. Solidshell elements are usually preferred for the discretization in the presence of complex material behavior and degradation phenomena such as delamination, since they allow for a correct representation of the thickness geometry. However, in solid-shell elements the small thickness leads to a very high maximum eigenfrequency, which imply very small stable time-steps. A new selective mass scaling technique is proposed to increase the time-step size without affecting accuracy. New ”directional” cohesive interface elements are used in conjunction with selective mass scaling to account for the interaction with a sharp blade in cutting processes of thin ductile shells

The Hierarchical Control Method for Coordinating a Group of Connected Vehicles on Urban Roads

Safety, mobility and environmental impact are the three major challenges in today\u27s transportation system. As the advances in wireless communication and vehicle automation technologies, they have rapidly led to the emergence and development of connected and automated vehicles (CAVs). We can expect fully CAVs by 2030. The CAV technologies offer another solution for the issues we are dealing with in the current transportation system. In the meanwhile, urban roads are one of the most important part in the transportation network. Urban roads are characterized by multiple interconnected intersections. They are more complicated than highway traffic, because the vehicles on the urban roads are moving in multiple directions with higher relative velocity. Most of the traffic accidents happened at intersections and the intersections are the major contribution to the traffic congestions. Our urban road infrastructures are also becoming more intelligent. Sensor-embedded roadways are continuously gathering traffic data from passing vehicles. Our smart vehicles are meeting intelligent roads. However, we have not taken the fully advantages of the data rich traffic environment provided by the connected vehicle technologies and intelligent road infrastructures. The objective of this research is to develop a coordination control strategy for a group of connected vehicles under intelligent traffic environment, which can guide the vehicles passing through the intersections and make smart lane change decisions with the objective of improving overall fuel economy and traffic mobility. The coordination control strategy should also be robust to imperfect connectivity conditions with various connected vehicle penetration rate. This dissertation proposes a hierarchical control method to coordinate a group of connected vehicles travelling on urban roads with intersections. The dissertation includes four parts of the application of our proposed method: First, we focus on the coordination of the connected vehicles on the multiple interconnected unsignalized intersection roads, where the traffic signals are removed and the collision avoidance at the intersection area relays on the communication and cooperation of the connected vehicles and intersection controllers. Second, a fuel efficient hierarchical control method is proposed to control the connected vehicles travel on the signalized intersection roads. With the signal phase and timing (SPAT) information, our proposed approach is able to help the connected vehicles minimize red light idling and improve the fuel economy at the same time. Third, the research is extended form single lane to multiple lane, where the connected vehicle discretionary and cooperative mandatory lane change have been explored. Finally, we have analysis the real-world implementation potential of our proposed algorithm including the communication delay and real-time implementation analysis

Electric field-induced directed assembly of diblock copolymers and grain boundary grooving in metal interconnects

Das Anlegen eines elektrischen Feldes an Materialien hat eine faszinierende Wirkung. Unterschiedliche Werkstoffklassen sind einem externen elektrischen Feld entweder als ein Teil der Verarbeitung oder aufgrund der alleinigen Applikation ausgesetzt. Wenn das elektrische Feld für die Verarbeitung verwendet wird, kann dieses die Mikrostruktur in Metallen, Legierungen, Keramiken und Polymeren verändern, wodurch die physikalischen Eigenschaften verändert werden. Alternativ können mehrere Einsatzmöglichkeiten wie beispielsweise der Einsatz in elektronischen Geräten dazu führen, dass Materialien als Komponenten verwendet werden, die täglich intensiven Stromstärken ausgesetzt sind. Eine ständige Verlagerung der Atome kann zu Fehlern im offenen Stromkreis führen, wodurch die Zuverlässigkeit des gesamten Geräts beeinträchtigt wird. Mit Hilfe der Phasenfeldmethode wird in der vorliegenden Dissertation jeweils ein Anwendungsfall untersucht, in dem das elektrische Feld entweder positive oder negative Folgen haben kann. Im ersten Teil der Arbeit wird ein diffuses Grenzflächenmodell entwickelt und für die Untersuchung der gerichteten Selbstorganisation von symmetrischen Diblock-Copolymeren verwendet, die gleichzeitig durch das elektrische Feld, die Substrataffinität und die Beschränkung beeinflusst werden. Es werden verschiedene beschränkende Geometrien untersucht und eine Reihe an Phasendiagrammen für unterschiedliche Schichtdicken charakterisiert, die das Verhältnis zwischen dem elektrischen Feld und der Substratstärke zeigen. Zusätzlich zu der Ermittlung der vorhandenen parallelen, senkrechten und gemischten Lamellenphasen findet man, ähnlich wie bei den vorausgegangenen analytischen Berechnungen und experimentellen Beobachtungen, auch einen Bereich im Phasendiagramm, der einem Lamellenabstand der Größe eines halben Integrals entspricht, in dem hybride Morphologien wie Benetzungsschichten in der Nachbarschaft des Substrats koexistieren, die entweder Löcher in der Mitte der Schicht oder senkrechte zylinderförmige Bereiche aufweisen. Des Weiteren wird die Untersuchung auf drei Dimensionen erweitert, in denen die letztgenannte Morphologie als eine hexagonal perforierte (HPL) Lamellenphase charakterisiert wird. Erstmals wird gezeigt, dass durch ein elektrisches Feld ein Ordnungs-Ordnungs-übergang von einer Lamellenphase zu einer HPL-Phase hervorgerufen werden kann. Außerdem zeigt der kinetische Verlauf des Übergangs, dass es sich bei den perforierten Lamellen, die während des Übergangs von parallelen zu senkrechten Lamellen in Dünnschichten entstehen, um Zwischenstrukturen handelt. Im Folgenden werden verschiedene Beschädigungsarten erläutert, die aufgrund der Elektromigration (EM) in Nanoverbindungen durch die Rille der Korngrenze verursacht werden. Dazu wird ein einkomponentiges, polykristallines Phasenfeldmodell verwendet, das die Windstärke der Elektronen berücksichtigt. Das Modell und dessen numerische Umsetzung wird erst mit der scharfen Grenzflächentheorie von Mullins verglichen, bei der die thermische Rillenbildung durch Oberflächendiffusion vermittelt wird. Anschließend wird gezeigt, dass die Art der durch die fortschreitende Elektromigration verursachten Schädigung stark durch einen Fluss durch Grenzflächen beeinträchtigt werden kann, der aufgrund der Elektromigration stattfindet. Ein schneller atomarer Transport entlang der Oberfläche führt zu einer formerhaltenden Versetzung der Oberfläche, während der Schaden durch einen schnelleren atomaren Transport durch Grenzflächen in Form von interkristallinen Schlitzen mit einer formerhaltenden Spitze lokalisiert wird. Durch die Phasenfeldsimulationen wird die Funktion von krümmungs- und EM-induzierten heilenden Strömungen entlang der Oberfläche weiter hervorgehoben, die die Rille wieder auffüllen und die Schadensausbreitung verzögern. Erstmals wird ein numerisches Modell erweitert, um die räumlich-zeitliche Schadenseinleitung, die Ausbreitung, die Selbstheilung und die Kornvergröberung in dreidimensionalen Verbindungen zu untersuchen. Anschließend zeigt ein kritischer Vergleich der aus der scharfen Grenzflächenmethode und der Phasenfeldmethode gewonnenen Lösungen bezüglich der Rillenbildung, dass sowohl bei der Ermittlung der Rillenformen als auch beim Verlauf der Schadensart erhebliche Fehler entstehen können, wenn der durch die Elektromigration induzierte Oberflächenfluss in den Theorien der scharfen Grenzflächen nicht berücksichtigt wird. Zur Beseitigung der Diskrepanzen wird schließlich ein neues scharfes Grenzflächenmodell für finite Körner formuliert, das die zeitgleiche Kapillarwirkung und den durch die Elektromigration induzierten Oberflächen- und Grenzflächenfluss berücksichtigt. Die mit dem neuen Modell getroffenen Vorhersagen zeigen eine sehr gute Übereinstimmung mit dem Phasenfeldmodell. Durch die Ergebnisse der vorliegenden Arbeit wird die Durchführbarkeit und Anwendbarkeit der Phasenfeldmethode in Bezug auf die Erfassung der erforderlichen Physik des Problems und in Bezug auf die Bewältigung der mikrostrukturellen Entwicklung effizient und elegant in einem Phänomen verdeutlicht, das durch ein elektrisches Feld verursacht wird

A new method for modelling reinforcement and bond in finite element analysis of reinforced concrete

In conventional finite element analysis of reinforced concrete the steel bars are normally assumed to lie along the concrete element edges and very often the bond gripping the steel to the concrete is assumed to be infinitely stiff. The first assumption makes it difficult to model all steel bars leading to the inclusion of only a few representative bars. Shear reinforcement is usually ignored. Thin concrete cover also creates difficulty by causing long thin finite elements in that region. The second assumption does not reflect the true behaviour of the system. In this research a new method for the modelling of steel in reinforced concrete by finite element analysis has been developed which allows all steel reinforcement to be included in the analysis. The method is based on modelling the steel and concrete separately, the two materials being interconnected by the bond forces between them. Thus, bond stiffness is naturally included in the analysis. Such interconnection of steel and concrete is achieved by an interface bond matrix which is derived from the relative displacements between the steel and the concrete at the steel nodes. A linear bond slip relation is assumed for the bond, and a linear stress strain relation is assumed for the concrete and the steel. The work has extended also to nonlinear bond stress-slip relation. Concrete is represented by 8-noded isoparametric quadrilateral elements, and the steel is represented by two noded bar elements. The bond is represented by springs joining each steel node to all 8-concrete nodes. The solution of the resulting system of equations is achieved in an iterative manner which converges quite rapidly, and which requires less computation than the direct solution needs. Three types of problems are analysed in two dimension to demonstrate the application of this new method. These are beam, cantilever and pullout problems. The first two, being real problems, demonstrate the ability of the method to handle complex steel arrangements, thin concrete covers and anchorage of steel, while the third problem shows the application of load to the steel rather than to the concrete. Concrete and steel deformations and stresses are calculated at their nodes. Bond stresses are given at all steel nodes. In the nonlinear bond analysis, deterioration of bond will be demonstrated in pullout and pushout tests at high loads

Robotic Path Planning for High-Level Tasks in Discrete Environments

This thesis proposes two techniques for solving high-level multi-robot motion planning problems with discrete environments. We focus on an important class of problems that require an allocation of spatially distributed tasks to robots, along with a set of efficient paths for the robots to visit their task locations. The first technique, SAT-TSP, models the problem with a framework that allows a natural coupling between the allocation problem and the path planning problem. The allocation problem is encoded as a Boolean Satisfiability problem (SAT) and the path planning problem is encoded as a Travelling Salesman Problem (TSP). In addition, this framework can handle complex constraints such as battery life limitations, robot carrying capacities, and robot-task incompatibilities. We propose an algorithm that leverages recent advances in Satisfiability Modulo Theory to combine state-of-the-art SAT and TSP solvers. We characterize the correctness of our algorithm and evaluate it in simulation on a series of patrolling, periodic routing, and multi-robot sample collection problems. The results show that our algorithm outperforms a state-of-the-art mathematical programming solver on a majority of the problems in our benchmark, especially the more difficult problems. The second technique, Gamma-Clustering, is used to reduce the computational effort of finding good solutions for metric discrete path planning problems. This technique can be used on the set of allocation path planning problems that do not have ordering constraints (ordering only affects the cost of the solution, not its feasibility). To obtain the computational savings, we find Gamma-Clusters within the problem's environment and then restrict how feasible paths visit these clusters. We prove that solutions found using this approach are within a constant factor of the optimal. By increasing the parameter Gamma we can improve the quality of the bound but we do so with less computational savings. We provide a simple polynomial-time algorithm for finding the optimal Gamma-Clustering and show that for a given Gamma the clustering is unique. We provide two methods for using Gamma-Clusters on path planning problems, a coupled method and a hierarchical method. We demonstrate the effectiveness of these methods on travelling salesman instances, sample collection problems, and period routing problems. The results show that for many instances we obtain significant reductions in computation time with little to no reduction in solution quality. Comparing these methods to a standard integer programming approach reveals that as the problems become more difficult, the solution quality of the two methods degrade at a slower rate than the standard approach, thus for more difficult instances we can use Gamma-Clustering to find higher quality solutions