<p> This thesis considers the problem of control of nonlinear process systems subject to input constraints and faults in the control actuators and process equipments. Faults are considered that preclude the possibility of continued operating at the nominal equilibrium point and a framework (which we call the safe-parking framework) is developed to enable efficient resumption of nominal operation upon fault-recovery. First, Lyapunov-based model predictive controllers, that allow for an explicit characterization of the stability region subject to constraints on the manipulated input, are designed. The stability region characterization is utilized in selecting 'safe-park' points from the safe-park candidates (equilibrium points subject to failed actuators). This safe-park point is chosen as a temporary operating point where process is to be operated during fault rectification. This ensures that process can be safely operated during fault rectification and the nominal operation can be resumed upon fault recovery. When multiple candidate safe-park points are available, performance considerations, such as ease of transition from and to the safe-park point and cost of running the process at the safe-park point, are quantified and utilized in choosing the optimal safe-park point. </p> <p> Next, we extend the safe-parking framework to handle practical issues such as plant-model mismatch, disturbances and unavailability of all process state measurements. \i\Te first consider the presence of constraints and uncertainty and develop a robust Lyapunov-based model predictive controller. This controller is utilized to characterize robust stability region which, subsequently, is utilized to select 'safepark' points. Then we consider the problem of availability of limited measurements. An output feedback Lyapunov-based model predictive controller, with high-gain observer to estimate unmeasured states, is formulated and its stability region explicitly characterized. An algorithm is then presented that accounts for the estimation errors in the implementation of the safe-parking framework. </p> <p> We then further extend the framework to handle faults in large scale chemical plants where multiple process units are connected via material, energy and information streams. In plant-wide setting, the safe-park point for the faulty unit is chosen such that the safe-parking has no or minimum effect on downstream units, and hence, the nominal operation in the downstream units can be continued. Next we consider the scenario where no viable safe-park point for the faulty unit exists such that its effect can be completely absorbed in the subsequent unit. A methodology is developed that allows simultaneous safe-parking of the consecutive units. The efficacy of the proposed framework is illustrated using a chemical reactor example, a styrene polymerization process and two CSTRs in series example. </p> <p> Finally, we demonstrate the efficacy of proposed Lyapunov based Model Predictive Controller and Safe-Parking framework on a polymerization reactor model to control the polymerization reactor and to handle faults that dont allow continuation of the nominal operation in the reactor. </p> / Thesis / Doctor of Philosophy (PhD)

Detecting a change in the structure of a time series is a classical statistical problem. Here we consider a short memory causal linear process $X_i=\sum_{j=0}^\infty a_j\xi_{i-j}$, $i=1,\cdots,n$, where the innovations $\xi_i$ are independent and identically distributed and the coefficients $a_j$ are summable. The goal is to detect the existence of an unobserved time at which there is a change in the marginal distribution of the $X_i$'s. Our model allows us to simultaneously detect changes in the coefficients and changes in location and/or scale of the innovations. Under very simple moment and summability conditions, we investigate the asymptotic behaviour of the sequential empirical process based on the $X_i$'s both with and without a change-point, and show that two proposed test statistics are consistent. In order to find appropriate critical values for the test statistics, we then prove the validity of the moving block bootstrap for the sequential empirical process under both the hypothesis and the alternative, again under simple conditions. Finally, the performance of the proposed test statistics is demonstrated through Monte Carlo simulations.

This research assesses shifts in tornado occurrence pattens in space and time employing continental United States tornado records with an Enhanced Fujita (EF) rating equal or greater than 1. In similar research, most researchers discard tornado records prior to 1980 due to factors including: magnitude anomalies related to development of the Fujita Scale, unpredictability in tornado reporting (escalating populace, storm spotters, and technologic improvements), and better data records from the Census Bureau. We therefore constructed two datasets using tornados recorded in the National Weather Service Storm Prediction Center’s Severe Weather GIS (SVRGIS) database: 1950-2019 (dataset 1) and 1980-2019 (dataset 2). The goals for this study were to 1) determine whether spatiotemporal patterns of recorded tornado activity have shifted over time, and 2) determine whether inclusion of pre-1980 tornado data changes the findings from 1). This study employed Space-Time Pattern Mining (STPM) to construct four spacetime cubes (STC) in ArcGIS Pro. Emerging Hot Spot Analysis (EHS) was employed to identify the changes in tornado occurrence (number of incidents in a STC cell) and magnitude (sum of tornado EF ratings for all incidents in a STC cell). EHS displayed increased tornado activity in the Southeast and decreased activity for areas in the Great Plains for both occurrence and magnitude in both datasets. This is interpreted as significant intensifying hot spots in the Southeast region and diminishing hot spots in the Great Plains indicating an east-south-east shift for both datasets. Similar findings for both datasets indicate that inclusion of the less reliable pre-1980’s tornado data does not change the results and we recommend that the practice of discarding pre-1980’s tornado data in tornado occurrence research be reconsidered.

Indiana University-Purdue University Indianapolis (IUPUI) / A popular non-invasive brain activity measurement method is based on the functional magnetic resonance imaging (fMRI). Such data are frequently used to study functional connectivity (FC) defined as statistical association among two or more anatomically distinct fMRI signals (Friston, 1994). FC has emerged in recent years as a valuable tool for providing a deeper understanding of neurodegenerative diseases and neuropsychiatric disorders, such as Alzheimer's disease and autism. Information about complex association structure in high-dimensional fMRI data is often discarded by a calculating an average across complex spatiotemporal processes without providing an uncertainty measure around it. First, we propose a non-parametric approach to estimate the uncertainty of dynamic FC (dFC) estimates. Our method is based on three components: an extension of a boot strapping method for multivariate time series, recently introduced by Jentsch and Politis (2015); sliding window correlation estimation; and kernel smoothing. Second, we propose a two-step approach to analyze and summarize dFC estimates from a task-based fMRI study of social-to-heavy alcohol drinkers during stimulation with avors. In the first step, we apply our method from the first paper to estimate dFC for each region subject combination. In the second step, we use semiparametric additive mixed models to account for complex correlation structure and model dFC on a population level following the study's experimental design. Third, we propose to utilize the estimated dFC to study the system's modularity defined as the mutually exclusive division of brain regions into blocks with intra-connectivity greater than the one obtained by chance. As a result, we obtain brain partition suggesting the existence of common functionally-based brain organization. The main contribution of our work stems from the combination of the methods from the fields of statistics, machine learning and network theory to provide statistical tools for studying brain connectivity from a holistic, multi-disciplinary perspective.

This research estimated the spatial-temporal patterns of tornadoes in the continental United States from 1950-2019 using the National Weather Service Storm Prediction Center’s Severe Weather GIS (SVRGIS) database. This study employed Space-Time Cube Analysis and Linear Kernel Density (Kernel Density Linear Process, (KDLP)) rather than the standard Kernel Density Estimation (KDE) approach; to evaluate whether tornado hotspot locations and intensities shift over time. The first phase of the study utilized KDLP to map changes in tornado hotspots and qualitatively assess decadal shifts in hotspot locations and intensities by occurrence and magnitude between decades using ArcGIS Pro and CrimeStat. Next an Emerging Hot Spot Analysis (EHSA) was employed to identify the changes in tornado occurrence and magnitude. ESHA results identified, by both occurrence and magnitude, significant intensifying hot spots in the Southeast region and diminishing hot spots in the Great Plains indicating an east-south-east shift.

In this work we deal with the Beveridge-Nelson decomposition of a linear process into a trend and a cyclical component. First, we generalize the decom- position for multidimensional linear process and then we use it to prove some of the limit theorems for the process and its special cases, processes VAR and VARMA. Further, we define the concept of cointegration and introduce the po- pular VEC model for cointegrated time series. Finally, we show a method how to deal with infinite sums appearing in calculation of the Beveridge-Nelson decom- position and apply it to real data. Then we compare the results of this method with approximations using partial sums.

L’amortissement de vibrations mécaniques trouve de nombreuses applications dans le domaine du contrôle acoustique ou de la réduction de contraintes dans l’industrie (machine outil), le génie civil (structure autoportée), ou encore l’aéronautique (réduction de contrainte lors des manoeuvres). Les recherches actuelles tendent principalement vers des méthodes utilisant des matériaux piézoélectriques collés à la surface des structures à traiter. Une technique prometteuse, développée au LGEF à l’INSA de Lyon, est l’amortissement de vibration d’une structure mécanique par méthode SSDI (pour Synchronized Switch Damping on an Inductor). Cette technique d’amortissement semi-active exploite un procédé non-linéaire de traitement de la tension aux bornes d’un élément piézoélectrique, capteur et actionneur à la fois. L’objectif de ce travail est de réaliser l’intégration de l’électronique de traitement de la tension aux bornes des éléments piézoélectriques en technologie microélectronique, afin de pouvoir l’embarquer sur le patch piézoélectrique à terme. Une analyse des techniques d’amortissement publiées permet d’y situer ce travail et de définir les points clés de la technique SSDI. Au deuxième chapitre, un certain nombre de modèles sont développés pour comparer et guider les choix de conception, et pour aboutir à des arbitrages architecturaux. Le troisième chapitre développe la conception d’un ASIC dans une technologie avec option haute tension, comprenant une fonction haute-tension de traitement du signal piézoélectrique et une chaine basse-tension d’analyse, de décision et de commande. La première réalise l’inversion de la tension piézoélectrique à l’aide d’un circuit RLC passif de conversion de l’énergie. La seconde s’attache à la détection des extremums de manière à optimiser l’amortissement. Un diviseur de tension auto-adaptatif avec protection contre les surtensions ainsi qu’un détecteur de pic de tension permettent de réaliser cette opération. Ces fonctions sont caractérisées en simulations et mesures. Le fonctionnement de l’ASIC est ensuite testé sur une structure mécanique, et les performances sont décrites et interprétées au chapitre 4. Le comportement multi-mode et la grande dynamique des signaux mécaniques traités sont des avancées par rapport à la bibliographie. / Mechanical vibration damping has many applications in industry (machine tools), civil engineering (bridge construction), or aeronautics (stress during maneuvers). Current research tends mainly to use piezoelectric materials based methods. A promising technique from the LGEF of INSA Lyon is the vibration damping of mechanical structure by so-called SSDI method (for Synchronized Switch Damping on an Inductor). This semi-active damping technique uses a non-linear process to invert the voltage across a piezoelectric element. The element is used as sensor and actuator at a time. The aim of this work is to achieve an integration of the electronic process with the SSDI voltage inversion in a microelectronic technology. It has ultimately to embed the electronic controller on the piezoelectric patch. The analysis of published damping techniques can situate this work and identify key points of the SSDI technique. In the second chapter, several models are developed to compare and decide of the best architectural design choice. The third chapter presents an ASIC design in a technology with high voltage option. The ASIC consists of a high-voltage piezoelectric signal processing part and a low-voltage control part. The first function performs piezoelectric voltage reversing by mean of a passive RLC energy conversion circuit. The second function focuses on the extremum voltage detection circuit in order to optimize damping efficiency. A self-tuning voltage divider with over-voltage protection and a peak voltage detector can perform this operation. These functions are characterized by simulations and measurements. The ASIC operation is then tested with mechanical structures, and damping performances are described and interpreted in Chapter 4. The multimodal behavior and the mechanical signals high-dynamic are new contribution as regard in the bibliography.

Sedan etableringen 2017 har en drastisk ökning av elscootrar skett i Sverige och framförallt i Stockholms innerstad. Denna radikala förändring inom färdmedel har skakat om den rådande trafikmiljön. Olyckor och parkeringsproblematik har stått i fokus för medias rapportering kring fenomenet. Syftet med denna rapport är att undersöka hur företagen som utvecklar elscootrar arbetar med säkerhet för användarna och anpassar sin produktutveckling efter svenska lagar och trafikregler. Studien behandlar även hur man på ett säkert sätt kan integrera nya färdmedel i samhället. För att lägga en grund för arbetet har en litteraturstudie genomförts och en teoretisk referensram tagits fram. Informationsinsamlingen har skett genom kvalitativa semistrukturerade intervjuer med tre företag som utvecklar eller hanterar elscootrar, ansvarig för elscootrar på Stockholms Stad samt respondenter från Transportstyrelsen med regeringsuppdraget Att utreda behov av förenklade regler av eldrivna enpersonsfordon. Intervjuerna har transkriberats, kodats, delats upp i teman och analyserats. Idag är de flesta elscootrar som finns i Stockholm klassificerade som cyklar. Detta innebär utöver krav på bland annat broms och ringklocka att maxhastigheten ej får överstiga 20 km/h och motoreffekten max får vara 250 W. Flera aktörer ser en problematik i detta och en gemensam önskan hos alla respondenter är att hitta en klassificering som ger tydlighet för vad som gäller, reder ut oklarheter och främjar utvecklingen av färdmedlet. Resultatet av studien har visat att ett stort fokus ligger på säkerhet i utvecklingsprocessen och en stor del av arbetet med säkerheten sker i utvärderingsfasen. Utvecklingen sker inkrementellt för att ständigt förbättra säkerheten hos elscootrarna och förhindra att olyckor sker. Idag arbetar företag med en mer linjär process men för att hantera framtida utmaningar skulle en mer agil process kunna främja produktutvecklingen. Då att fenomenet med elscootrar fortfarande är nytt så är olycksstatistiken som finns ytterst begränsad. Den som finns pekar dock på att olycksgraden med elscootrar involverade inte är högre än för traditionella cyklar. Studien visar också att det sker en dialog mellan Stockholms Stad och de ledande scooter-företagen i Stockholm för att på ett säkert sätt integrera färdmedlet i stadstrafiken. / Since its establishment in 2017, there has been a dramatic increase of e-scooters in Sweden and especially in Stockholm city. This radical change in transport has shaken the current traffic environment. Accidents and parking problems have been the focus of media reporting of the phenomenon. The purpose of this report is to investigate how the companies that develop e-scooters work with safety for the users and adapt their product development to Swedish laws and traffic rules. The study also deals with how to safely integrate new means of transport into society. In order to lay a foundation, a literature study has been conducted and a theoretical frame of reference has been developed. Information was gathered through qualitative semi-structured interviews with three companies that develop e-scooters, responsible for e-scooters in Stockholms Stad and respondents from the Swedish Transport Agency with a government assignment to clarify the situation. The interviews have been transcribed, coded, subdivided into themes and analyzed. Today, most e-scooters in Stockholm are classified as bicycles. This means, in addition to requirements for brake and bell, that the speed must not exceed 20 km/h and the engine power must be no more than 250 W. Several affecting parties consider this classification problematic and a common wish among all interviewed respondents is to find a classification or approach to the e-scooters that gives clarity for which rules that applies, clarifies ambiguities and promotes future development of the e-scooters. The results of the study have shown that a large focus in the development process is on safety and a large part of the work to enhance safety takes place during the evaluation phase. The development is incremental in order to constantly improve the safety for the users of the e-scooters and prevent accidents from happening. Today, companies are working with a relatively linear development process, but in order to handle future challenges, a more agile work process could promote product development. Since the phenomenon of e-scooters is still new, the accident statistics are very limited. However, the statistics that exist point out that the accident rates with e-scooters involved is not higher than for traditional bicycles. The study also shows that there is a dialogue between Stockholms Stad and the leading scooter companies in Stockholm in order to safely integrate the means of transport into city traffic.

Research and Development engineering is at the corner stone of humanity’s evolution. It is perceived to be a systematic creative process which ultimately improves the living standard of a society through the creation of new applications and products. The commercial paradigm that governs project selection, resource allocation and market penetration prevails when the focus shifts from pure research to applied research. Furthermore, the road to success through commercialisation is difficult for most inventors, especially in a vast and isolated country such as Australia which is located a long way from wealthy and developed economies. While market leading products are considered unique, the actual process to achieve these products is essentially the same; progressing from an idea, through development to an outcome (if successful). Unfortunately, statistics indicate that only 3% of ‘ideas’ are significantly successful, 4% are moderately successful, and the remainder ‘evaporate’ in that form (Michael Quinn, Chairman, Innovation Capital Associates Pty Ltd). This study demonstrates and analyses two techniques developed by the author which reduce uncertainty in the engineering design and development phase of new product development and therefore increase the probability of a successful outcome. This study expands the existing knowledge of the engineering design and development stage in the new product development process and is couched in the identification of practical methods, which have been successfully used to develop new products by Australian Small Medium Enterprise (SME) Excel Technology Group Pty Ltd (ETG). Process theory is the term most commonly used to describe scientific study that identifies occurrences that result from a specified input state to an output state, thus detailing the process used to achieve an outcome. The thesis identifies relevant material and analyses recognised and established engineering processes utilised in developing new products. The literature identified that case studies are a particularly useful method for supporting problem-solving processes in settings where there are no clear answers or where problems are unstructured, as in New Product Development (NPD). This study describes, defines, and demonstrates the process of new product development within the context of historical product development and a ‘live’ case study associated with an Australian Government START grant awarded to Excel Technology Group in 2004 to assist in the development of an image-based vehicle detection product. This study proposes two techniques which reduce uncertainty and thereby improve the probability of a successful outcome. The first technique provides a predicted project development path or forward engineering plan which transforms the initial ‘fuzzy idea’ into a potential and achievable outcome. This process qualifies the ‘fuzzy idea’ as a potential, rationale or tangible outcome which is within the capability of the organisation. Additionally, this process proposes that a tangible or rationale idea can be deconstructed in reverse engineering process in order to create a forward engineering development plan. A detailed structured forward engineering plan reduces the uncertainty associated with new product development unknowns and therefore contributes to a successful outcome. This is described as the RETRO technique. The study recognises however that this claim requires qualification and proposes a second technique. The second technique proposes that a two dimensional spatial representation which has productivity and consumed resources as its axes, provides an effective means to qualify progress and expediently identify variation from the predicted plan. This spatial representation technique allows a quick response which in itself has a prediction attribute associated with directing the project back onto its predicted path. This process involves a coterminous comparison between the predicted development path and the evolving actual project development path. A consequence of this process is verification of progress or the application of informed, timely and quantified corrective action. This process also identifies the degree of success achieved in the engineering design and development phase of new product development where success is defined as achieving a predicted outcome. This spatial representation technique is referred to as NPD Mapping. The study demonstrates that these are useful techniques which aid SMEs in achieving successful new product outcomes because the technique are easily administered, measure and represent relevant development process related elements and functions, and enable expedient quantified responsive action when the evolving path varies from the predicted path. These techniques go beyond time line representations as represented in GANTT charts and PERT analysis, and represent the base variables of consumed resource and productivity/technical achievement in a manner that facilitates higher level interpretation of time, effort, degree of difficulty, and product complexity in order to facilitate informed decision making. This study presents, describes, analyses and demonstrates an SME focused engineering development technique, developed by the author, that produces a successful new product outcome which begins with a ‘fuzzy idea’ in the mind of the inventor and concludes with a successful new product outcome that is delivered on time and within budget. Further research on a wider range of SME organisations undertaking new product development is recommended.