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During recent years, many sites with sediments pre-dating the Last Glacial Maximum have been identified in formerly glaciated areas. As more and better dates are presented from these sites, the dynamic behaviour of the Scandinavian Ice Sheet is becoming increasingly clear. In this study, we revisited the site Skorgenes in western Norway. Here, sediments from two ice-free periods are found below an
Megacephalosaurus eulerti is a large macropredatory plesiosaur representing one of the last members of the diverse pliosaurid clade Brachaucheninae. The taxon was established upon a nearly complete skull including the mandible and fragments of the postcranial skeleton originating from the lower middle Turonian (Upper Cretaceous) of Kansas, USA. Owing to its age, reasonable completeness and its sta
Purpose: Patients with acromegaly have an increased risk of sleep apnea, but reported prevalence rates vary largely. Here we aimed to evaluate the sleep apnea prevalence in a large national cohort of patients with acromegaly, to examine possible risk factors, and to assess the proportion of patients diagnosed with sleep apnea prior to acromegaly diagnosis. Methods: Cross-sectional multicenter stud
This study grounds a highly charged debate on agriculture in developing countries within economic theory, by establishing a structured analytical framework for considering the potential role of foreign investment in supporting agricultural development. The framework is developed to be time and space neutral, such that it can be utilized in various geographic settings and across different time peri
This paper shows an application of continuous-time system identification methods to Type 1 diabetes. First, a general MISO transfer function structure with individual nominator and denominator polynomials for each input is assumed and a parameter estimation procedure via an iterative prediction error method presented. Then, the proposed identification method is evaluated on a simple simulation exa
A drilling task requires a mechanism with five degrees of freedom, in order to achieve the correct position and orientation of the drilling tool. When performed with a standard 6-axes industrial robot, this task leaves an extra degree of freedom that can be exploited in order to achieve any additional criterion. Unfortunately, typical industrial robotic control architectures do not allow the user
Modern industrial robots are fast and have very good repetitional accuracy, which have made them indispensable in many manufacturing applications. However, they are usually programmed to follow desired trajectories and only get feedback from position sensors. This works fine as long as the environment is very well structured, but does not give good robustness to objects not being positioned or gri
This contribution reviews theory, algorithms, and validation results for system identification of continuous-time state-space models from finite input-output sequences. The algorithms developed are autoregressive methods, methods of subspace-based model identification and stochastic realization adapted to the continuous-time context. The resulting model can be decomposed into an input-output model
The focus of this article is to undertake a comparative analysis of multi-step-ahead linear multivariate predictors. The approach considered for the estimation will be based on geometrically reliable linear algebra tools, resorting to subspace identification methods. A crucial issue is quantification of both bias error and variance affecting the estimate of the prediction for increasing values of
The well-known and commonly accepted finite dimensional model qualitatively describing surge instabilities in centrifugal (and axial) compressors is considered. The problem of global output feedback stabilization for it is solved. The solution relies on two new criteria for global stability proposed for a class of nonlinear systems exploiting quadratic constraints for infinite sector nonlinearitie
This paper presents theory, algorithms and validation results for system identification of continuous-time state-space models from finite non-uniformly sampled input-output sequences. The algorithms developed are methods of model identification and stochastic realization adapted to the continuous-time model context using non-uniformly sampled input-output data. The resulting model can be decompose
Using methods of system identification and prediction, we investigate near-future prediction of individual specific T1DM blood glucose dynamics with the purpose of a decision-making tool development in diabetes treatment. Two strategies were approached: Firstly, Kalman estimators based on identified state-space models were designed; Secondly, direct identification of ARX- and ARMAX-based predictor
Stability problems associated with robot control with obstacle avoidance are analyzed.Obstacle avoidance algorithms based on potential function are revised to accomplish stable re-design. A stability proof using Lyapunov theory and passivity theory is provided for the re-designed obstacle avoidance algorithm. The paper presents a modification of potential functions for obstacle avoidance aiming to
Control of robotic systems subject to friction phenomena is an important issue since growing demands on accuracy require elimination of friction disturbances. If several modelse.g., friction model, rigid-body dynamicsare required to describe the behavior with high precision, each model requires the knowledge of numerous parameters (perhaps time-varying) as well as an increased number of signals an
To facilitate model-based control of combustion timing and work output in Homogeneous Charge Compression Ignition (HCCI) engines, a cycle-resolved model of HCCI incorporating cylinder wall temperature dynamics is presented. Heat transfer between the in-cylinder charge and the cylinder walls is important for explaining HCCI cycle-to-cycle behaviour but is rarely included in control-oriented models.
Due to the possibility of increased efficiency and reduced emissions, Homogeneous Charge Compression Ignition (HCCI) is a promising alternative to conventional internal combustion engines. Ignition timing in HCCI is highly sensitive to operating conditions and lacks direct actuation, making it a challenging subject for closed-loop control. This paper presents results on model-based control of igni
The paper suggests conditions for presence of quadratic Lyapunov functions for nonlinear observer based feedback systems with an input nonlinearity in the feedback path. Provided that the system using state feedback satisfies the circle criterion (i.e., when all states can be measured), we show that stability of the extended system with output feedback control from a (full state) Luenberger-type o
