The existing powertrain control system in Volvo CE's vehicles consists of various types of physical quantities that are controlled. One of them is the engine speed. The purpose of this thesis is to investigate whether there are other control strategies suitable for engine speed control, than the existing one. Currently, the existing control system requires re-calibration of the control parameters if hardware in the vehicle is replaced. The current controller is a gain-scheduled PID controller with control parameters that varies over the operating range. The aim has been to develop several different adaptive control strategies. Adaptive control methods are expected to adapt to the changes of the system that a replacement of hardware can bring. The performance and robustness of the developed controllers have been compared with the existing controller. The approach has been to implement the control strategies in Matlab/Simulink and simulate the process with existing engine software provided by Volvo CE. The next step was to test and verify the controllers in a real machine. The focus in this thesis work has been on the adaptive control strategies MRAC (Model-Reference Adaptive Control) and L1 Adaptive Control. In the MRAC structure the desired performance is specified in terms of a reference model that the real system is supposed to follow. Each time an error is generated, by comparing actual and desired output, a suitable algorithm is used in order to obtain the control signal that can minimize the error. In addition, modeling errors and disturbances are estimated so that the controller can compensate for these. L1 Adaptive Control is an extension of the MRAC structure. The difference is that before the control signal is fed to the real system, it is low-pass filtered. This is done in order to prevent feeding high frequencies into the system. The results show that adaptive control has potential to be used in engine speed control. Reference following and disturbance rejection is well handled and simulations have furthermore shown that the developed controllers can deal with changes in the hardware. One of the developed L1-controllers was implemented in a real machine with promising results. / Det existerande styrsystemet i Volvo CE:s maskiner har till uppgift att styra och reglera flera olika fysikaliska storheter. En av dessa storheter är motorvarvtalet. Syftet med detta examensarbete är att undersöka alternativa reglerstrategier som kan användas för att styra motorvarvtalet. Problemet idag är att det nuvarande styrsystemet kräver omkalibrering av regulatorparametrar när befintlig hårdvara i maskinen behöver ersättas på grund av föråldring eller slitage. Den nuvarande regulatorn är en parameterstyrd PID-regulator där regulatorparametrarna beror av aktuell arbetspunkt. Målet har varit att utveckla och prova flera olika adaptiva reglerstrategier. Dessa metoder förväntas kunna hantera förändringar och adaptera sig mot nya förhållanden och omständigheter som en hårdvaruförändring kan medföra. Prestanda och robusthet som de utvecklade regulatorerna erhåller har jämförts mot den existerande regulatorstrukturen. Tillvägagångssättet har varit att implementera reglerstrategierna i Matlab/Simulink samt simulera med tillhörande motormjukvara som Volvo CE tillhandahållit. I nästa fas skulle regulatorerna testas och verifieras i en riktig maskin. Fokuset har under detta examensarbete riktats mot de två adaptiva reglerstrategierna Model-Reference Adaptive Control (MRAC) och L1 Adaptive Control. MRAC-strukturen bygger på att specificera prestandan genom en referens-modell som det riktiga systemet skall följa. Varje gång en avvikelse uppstår så beräknas en lämplig styrsignal genom att beakta och försöka minimera skillnaden mellan det riktiga systemet och den önskade referens-modellen. Till detta modelleras och skattas störningar som regulatorn skall kompensera för. Tekniken inom L1 Adaptive Control är en utvidgning av MRAC. Önskat beteende specificeras även för denna regulatorstruktur men största skillnaden är att innan styrsignalen matas in till systemet så lågpassfiltreras den. Detta görs i förebyggande syfte för att inte släppa in onödigt höga frekvenser in i systemet. Resultaten visar att adaptiv reglering av motorvarvtalet har potential. Referensföljning och undertryckning av störningar hanteras väl och simuleringar har dessutom visat att de utvecklade regulatorerna kan hantera hårdvaruändringar. En av de utvecklade L1-regulatorerna implementerades i en riktig maskin och resultaten såg lovande ut.

Metagenomics holds unyielding potential in uncovering relationships within microbial communities that have yet to be discovered, particularly because the field circumvents the need to isolate and culture microbes from their natural environmental settings. A common research objective is to detect biomarkers, microbes are associated with changes in a status. For instance, determining such microbes across conditions such as healthy and diseased groups for instance allows researchers to identify pathogens and probiotics. This is often achieved via analysis of differential abundance of microbes. The problem is that differential abundance analysis looks at each microbe individually without considering the possible associations the microbes may have with each other. This is not favorable, since microbes rarely act individually but within intricate communities involving other microbes. An alternative would be variable selection techniques such as Lasso or Elastic Net which considers all the microbes simultaneously and conducts selection. However, Lasso often selects only a representative feature of a correlated cluster of features and the Elastic Net may incorrectly select unimportant features too frequently and erratically due to high levels of sparsity and variation in the data.\par In this research paper, the proposed method AdaLassop is an augmented variable selection technique that overcomes the misgivings of Lasso and Elastic Net. It provides researchers with a holistic model that takes into account the effects of selected biomarkers in presence of other important biomarkers. For AdaLassop, variable selection on sparse ultra-high dimensional data is implemented using the Adaptive Lasso with p-values extracted from Zero Inflated Negative Binomial Regressions as augmented weights. Comprehensive simulations involving varying correlation structures indicate that AdaLassop has optimal performance in the presence multicollinearity. This is especially apparent as sample size grows. Application of Adalassop on a Metagenome-wide study of diabetic patients reveals both pathogens and probiotics that have been researched in the medical field.

The problem of parameter and state estimation of a class of nonlinear systems is addressed. An adaptive identifier and observer are used to estimate the parameters and the state variables simultaneously. The proposed method is derived using a new formulation. Uncertainty sets are defined for the parameters and a set of auxiliary variables for the state variables. An algorithm is developed to update these sets using the available information. The algorithm proposed guarantees the convergence of parameters and the state variables to their true value. In addition to its application in difficult estimation problems, the algorithm has also been adapted to handle fault detection problems. The technique of estimation is applied to two broad classes of systems. The first involves a class of continuous time nonlinear systems subject to bounded unknown exogenous disturbance with constant parameters. Using the proposed set-based adaptive estimation, the parameters are updated only when an improvement in the precision of the parameter estimates can be guaranteed. The formulation provides robustness to parameter estimation error and bounded disturbance. The parameter uncertainty set and the uncertainty associated with an auxiliary variable is updated such that the set is guaranteed to contain the unknown true values. The second class of system considered is a class of nonlinear systems with timevarying parameters. Using a generalization of the set-based adaptive estimation technique proposed, the estimates of the parameters and state are updated to guarantee convergence to a neighborhood of their true value. The algorithm proposed can also be extended to detect the fault in the system, injected by drastic change in the time-varying parameter values. To study the practical applicability of the developed method, the estimation of state variables and time-varying parameters of salt in a stirred tank process has been performed. The results of the experimental application demonstrate the ability of the proposed techniques to estimate the state variables and time-varying parameters of an uncertain practical system. / Thesis (Master, Chemical Engineering) -- Queen's University, 2011-10-31 22:04:58.762

Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 140-155). / Also available by subscription via World Wide Web / xiii, 155 leaves, bound ill. 29 cm

Thesis (PhD)--University of South Australia, 2001

This thesis investigates techniques and algorithms for mitigating radio frequency interference (RFI) affecting radio astronomy observations. In the past radio astronomy has generally been performed in radio-quiet geographical locations and unused parts of the radio spectrum, including small protected frequency bands. The increasing use of the entire spectrum and global transmitters such as satellites are forcing the astronomy community to begin implementing active interference cancelling. The amount of harmful interference affecting observations will also increase as future instruments such as the Square Kilometre Array (SKA) are required to use larger bandwidths to reach up to 100 times the current sensitivity levels, and as spectral line observations require observing in bands licensed to other spectrum users. Particular attention is paid to interference cancellation algorithms which make use of reference beams. This has proven to be successful in removing interference from the contaminated astronomical data. Reference antenna cancellers are closely analysed, leading to filters and techniques that can offer improved RFI excision for some important applications. It is shown that pre- and post-correlation reference antenna cancellers give similar results, and an important aspect of the cancellers is the use of a second reference signal when the reference interference-to-noise ratio is low. These modified filters can theoretically offer infinite interference suppression in the voltage domain, equivalent to that of post-correlation interference cancellers, and their internal structure can offer an understanding of the residual RFI and added receiver noise components of a variety of reference antenna techniques. The effect of variable geometric delays is also considered and various filters are compared as a function of the geometric fringe rate.

Thesis (Ph. D.)--Ohio University, June, 1990. / Title from PDF t.p.

Thesis(M.S.)--Auburn University, 2007. / Abstract. Includes bibliographic references (p.64-66).

Thesis (Ph. D.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 140-155).

Thesis (M.Phil.) - University of Queensland, 2006. / Includes bibliography.