335 research outputs found
Efficient schemes on solving fractional integro-differential equations
Fractional integro-differential equation (FIDE) emerges in various modelling of
physical phenomena. In most cases, finding the exact analytical solution for FIDE is
difficult or not possible. Hence, the methods producing highly accurate numerical
solution in efficient ways are often sought after. This research has designed some
methods to find the approximate solution of FIDE. The analytical expression of
Genocchi polynomial operational matrix for left-sided and right-sided Caputo’s
derivative and kernel matrix has been derived. Linear independence of Genocchi
polynomials has been proved by deriving the expression for Genocchi polynomial
Gram determinant. Genocchi polynomial method with collocation has been
introduced and applied in solving both linear and system of linear FIDE. The
numerical results of solving linear FIDE by Genocchi polynomial are compared with
certain existing methods. The analytical expression of Bernoulli polynomial
operational matrix of right-sided Caputo’s fractional derivative and the Bernoulli
expansion coefficient for a two-variable function is derived. Linear FIDE with mixed
left and right-sided Caputo’s derivative is first considered and solved by applying the
Bernoulli polynomial with spectral-tau method. Numerical results obtained show that
the method proposed achieves very high accuracy. The upper bounds for th
Design of the VISITOR Tool: A Versatile ImpulSive Interplanetary Trajectory OptimizeR
The design of trajectories for interplanetary missions represents one of the most complex and important problems to solve during conceptual space mission design. To facilitate conceptual mission sizing activities, it is essential to obtain sufficiently accurate trajectories in a fast and repeatable manner. To this end, the VISITOR tool was developed. This tool modularly augments a patched conic MGA-1DSM model with a mass model, launch window analysis, and the ability to simulate more realistic arrival and departure operations. This was implemented in MATLAB, exploiting the built-in optimization tools and vector analysis routines. The chosen optimization strategy uses a grid search and pattern search, an iterative variable grid method. A genetic algorithm can be selectively used to improve search space pruning, at the cost of losing the repeatability of the results and increased computation time. The tool was validated against seven flown missions: the average total mission (Delta)V offset from the nominal trajectory was 9.1%, which was reduced to 7.3% when using the genetic algorithm at the cost of an increase in computation time by a factor 5.7. It was found that VISITOR was well-suited for the conceptual design of interplanetary trajectories, while also facilitating future improvements due to its modular structure
Numerical and Evolutionary Optimization 2020
This book was established after the 8th International Workshop on Numerical and Evolutionary Optimization (NEO), representing a collection of papers on the intersection of the two research areas covered at this workshop: numerical optimization and evolutionary search techniques. While focusing on the design of fast and reliable methods lying across these two paradigms, the resulting techniques are strongly applicable to a broad class of real-world problems, such as pattern recognition, routing, energy, lines of production, prediction, and modeling, among others. This volume is intended to serve as a useful reference for mathematicians, engineers, and computer scientists to explore current issues and solutions emerging from these mathematical and computational methods and their applications
Sviluppo di tecniche di monitoraggio delle prestazioni di processi chimici controllati
La tesi proposta tratta del monitoraggio delle prestazioni dei controllori in processi chimici. Diverse sono le cause di malfunzionamento: da valvole con attrito, a regolatori sintonizzati impropriamente alla propagazione di disturbi negli impianti. Con questa tesi si vuole illustrare una metodologia per individuare le cause di mancata prestazione in modo da poterle classificare ed intraprendere le necessarie contromisure. In particolare é stato approfondito il problema della sintonizzazione dei regolatori ed è stata proposta una tecnica di identificazione basata sullo studio dei disturbi, evitando quindi ulteriori sollecitazioni agli impianti per variazioni di set-point. Inoltre è stato affrontato il problema dell’attrito sulle valvole utilizzando diverse tecniche di individuazione automatica originali e già presentetate in letteratura. Il tutto è stato organizzato in un software sviluppato in ambiente Matlab
Advances in Condition Monitoring, Optimization and Control for Complex Industrial Processes
The book documents 25 papers collected from the Special Issue “Advances in Condition Monitoring, Optimization and Control for Complex Industrial Processes”, highlighting recent research trends in complex industrial processes. The book aims to stimulate the research field and be of benefit to readers from both academic institutes and industrial sectors
Towards Automated Design of Complex Modular Systems Inspired by Nature
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Systems and control problems in early systems design
This thesis is concerned with the evaluation of properties of early design models, the control structure selection and the representation and properties of composite system models. The work is motivated by the need to introduce a Systems and Control Theory based framework for early design stages of the overall system design of engineering processes, and in particular chemical processes, such as process synthesis and control structure selection. The overall spirit of the work is that engineering design is an evolutionary process, the different stages of which shape the structure of the resulting system models and precondition the potential for design at the next stage. The work identifies a number of key problems in the overall design, which are of a generic, systemic character, and then deals with working out solutions for such problems. The results contribute in the development of a framework for systems integration using as criteria and tools, those provided by Systems and Control Theory. The work aims to provide a control theoretic dimension to the rules and practices currently used in the specific application areas.
The thesis contributes in the development of a Systems and Control conceptual and tools framework for integrated design of engineering processes by providing results in the following areas:
- Specification of a number of generic problems in the field of integrated design and identification of relevant control theoretic concepts and tools.
- Study of Model Orientation for linear implicit state-space models and definition of classes of oriented realisations.
- Development of solutions to two problems of Structural Identification for uncertain early process models related to infinite zero structure and McMillan degree.
- Development of a generic representation of composite systems that allows the study of transition from the aggregate to composite system properties, as a generalised Control Design and characterisation of some key system properties.
-Specification of a framework for integrated Control Structure Selection and development of software for many approaches of the "interaction analysis" indicators.
The results contribute in the area of development of the systems and control ideas for the problems of systems integration and early design. The work emphasises the strong links between Modelling, Selection of Control Structures and Control Structural methodologies
A Comparative Analysis of Machine Learning Techniques For Foreclosure Prediction
The current decline in the U.S. economy was accompanied by an increase in foreclosure rates starting in 2007. Though the earliest figures for 2009 - 2010 indicate a significant decrease, foreclosure of homes in the U.S. is still at an alarming level (Gutierrez, 2009a). Recent research at the University of Michigan suggested that many foreclosures could have been averted had there been a predictive system that did not only rely on credit scores and loan-to-value ratios (DeGroat, 2009). Furthermore, Grover, Smith & Todd (2008) contend that foreclosure prediction can enhance the efficiency of foreclosure mitigation by facilitating the allocation of resources to areas where predicted foreclosure rates will be high.
The primary goal of this dissertation was to develop a foreclosure prediction model that builds upon established bankruptcy and credit scoring models. The study utilized and compared the predictive accuracy of three supervised machine learning (ML) techniques when applied to mortgage data. The selected ML techniques were:
ML1. Classification Trees
ML2. Support Vector Machines (SVM)
ML3. Genetic Programming
The data used for the study is comprised of mortgage data, demographic metrics and certain macro-economic indicators that are available at the time of the inception of the loan.
The hypothesis of the study was based on the assumption that foreclosure rates, and associated actions, are dependent on critical demographic (age, gender), economic (per capita income, inflation) and regional variables (predatory lending, unemployment index). The task of the machine learning techniques was to identify a function that well approximates the relationship between these explanatory variables and the binary outcome of interest (mortgage status in +3 years from inception).
The predictive accuracy of ML1 through ML3 was significantly better than expected given the size of the recordset (1000) and the number of input variables (~110). Each ML technique achieved classification accuracy better than 75%, with ML3 scoring in the upper 90s. Given such high scores, it was concluded that the hypothesis was satisfied and that ML techniques are suitable for prediction tasks in this problem domain
Using metarules to integrate knowledge in knowledge based systems. An application in the woodworking industry
The current study addresses the integration of knowledge obtained from Data Mining structures and models into existing Knowledge Based solutions. It presents a technique adapted from commonKADS and spiral methodology to develop an initial knowledge solution using a traditional approach for requirement analysis, knowledge acquisition, and implementation. After an initial prototype is created and verified, the solution is enhanced incorporating new knowledge obtained from Online Analytical Processing, specifically from Data Mining models and structures using meta rules. Every meta rule is also verified prior to being included in the selection and translation of rules into the Expert System notation. Once an initial iteration was completed, responses from test cases were compared using an agreement index and kappa index.
The problem domain was restricted to remake and rework operations in a cabinet making company. For Data Mining models, 8,674 cases of Price of Non Conformance (PONC) were used for a period of time of 3 months.
Initial results indicated that the technique presented sufficient formalism to be used in the development of new systems, using Trillium scale. The use of 50 additional cases randomly selected from different departments indicated that responses from the original system and the solution that incorporated new knowledge from Data Mining differed significantly. Further inspection of responses indicated that the new solution with additional 68 rules was able to answer, although with an incorrect alternative in 28 additional cases that the initial solution was not able to provide a conclusion
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