Stochastic Model Predictive Control for Linear Systems using Probabilistic Reachable Sets

In this paper we propose a stochastic model predictive control (MPC) algorithm for linear discrete-time systems affected by possibly unbounded additive disturbances and subject to probabilistic constraints. Constraints are treated in analogy to robust MPC using a constraint tightening based on the concept of probabilistic reachable sets, which is shown to provide closed-loop fulfillment of chance constraints under a unimodality assumption on the disturbance distribution. A control scheme reverting to a backup solution from a previous time step in case of infeasibility is proposed, for which an asymptotic average performance bound is derived. Two examples illustrate the approach, highlighting closed-loop chance constraint satisfaction and the benefits of the proposed controller in the presence of unmodeled disturbances.Comment: 57th IEEE Conference on Decision and Control, 201

Service Dominant Logic and Business Process Blueprinting: Enhancing the View on Performance by Integrating the Customer Perspective

Today process-oriented approaches to solve business challenges are state of the art. However most business process management methods focus on increased performance only from the firm’s perspective and neglect the increasing importance of value co-creation between the firm and the customer. Modern business process management methods not only need to concentrate on the internal performance of processes, but need to include the customer’s perspective. In this article we introduce the method of “Business Process Blueprinting” that combines both points of view. By enhancing business process modeling with the marketing concept of service blueprinting, we offer a method to visualize and analyze the firm’s and customer’s perspective within one integrated approach and reduce the gap between information management and marketing. This opens up the path towards an enhanced understanding of process performance in terms of a stronger inclusion of revenue into costing and analyzing and influencing subsequent usage processes

Cautious NMPC with Gaussian Process Dynamics for Autonomous Miniature Race Cars

This paper presents an adaptive high performance control method for autonomous miniature race cars. Racing dynamics are notoriously hard to model from first principles, which is addressed by means of a cautious nonlinear model predictive control (NMPC) approach that learns to improve its dynamics model from data and safely increases racing performance. The approach makes use of a Gaussian Process (GP) and takes residual model uncertainty into account through a chance constrained formulation. We present a sparse GP approximation with dynamically adjusting inducing inputs, enabling a real-time implementable controller. The formulation is demonstrated in simulations, which show significant improvement with respect to both lap time and constraint satisfaction compared to an NMPC without model learning

A risk analysis framework for real-time control systems

We present a Monte Carlo simulation framework for analysing the risk involved in deploying real-time control systems in safety-critical applications, as well as an algorithm design technique allowing one (in certain situations) to robustify a control algorithm. Both approaches are very general and agnostic to the initial control algorithm. We present examples showing that these techniques can be used to analyse the reliability of implementations of non-linear model predictive control algorithms.Comment: v2: Major changes. Corrected several theoretical issues in v1 and recomputed example

LOTSE feiert Geburtstag: 20 Jahre Kompass zum wissenschaftlichen Arbeiten

2002 wird LOTSE erstmals online gestellt. Seitdem unterstützt das Selbstlerninstrument Studierende und Wissenschaftler*innen bei ihrer Literaturrecherche und dem wissenschaftlichen Arbeiten. Was als Projekt an der ULB Münster beginnt, entwickelt sich zu einer Kooperationspartnerschaft mit 18 Bibliotheken, welche 2016 aufgelöst werden muss. Der Aufsatz blickt auf zwanzig Jahre LOTSE zurück und verrät, wie LOTSE heute weitergeführt wird.In 2002, LOTSE is put online for the first time. Since then, the self-learning tool has supported students and scientists in their literature search and scientific work. What began as a project at the ULB Münster developed into a cooperation partnership with 18 libraries, which had to be dissolved in 2016. The article looks back on twenty years of LOTSE and reveals how LOTSE is being continued today

Renal and hepatic function of patients with severe tricuspid regurgitation undergoing inferior caval valve implantation

Due to progressive abdominal-venous congestion severe tricuspid regurgitation (TR) is a common cause of cardiorenal and cardiohepatic syndrome. We initiated the TRICAVAL study to compare interventional valve implantation into the inferior vena cava (CAVI) versus optimal medical therapy (OMT) in severe TR. In the present subanalysis, we aimed to evaluate the effects of CAVI on clinical signs of congestion, renal and hepatic function. TRICAVAL was an investigator-initiated, randomized trial. Twenty-eight patients with severe TR were randomized to OMT or CAVI using an Edwards Sapien XT valve. Probands who completed the 3-month follow-up (CAVI [n = 8], OMT [n = 10]) were evaluated by medical history, clinical examination, and laboratory testing at baseline, 3 and 12 months. After 3 months, the CAVI group exhibited a significant reduction of body weight (from 80.7 [69.0-87.7] kg to 75.5 [63.8-84.6] kg, p < 0.05) and abdominal circumference (from 101.5 +/- 13.8 cm to 96.3 +/- 15.4 cm, p <= 0.01) and a trend to lower doses of diuretics compared to OMT. Renal and hepatic function parameters did not change significantly. Within a short-term follow-up, CAVI led to an improvement of clinical signs of venous congestion and a non-significant reduction of diuretic doses compared to OMT

Impact of inferior caval valve implantation on severity of tricuspid regurgitation and right heart function

Aims: Severe tricuspid regurgitation (TR) is a common finding in heart failure patients and associated with increased mortality. New interventional therapeutic options are needed as many heart failure patients are unfit for surgery. The TRICAVAL study compared valve implantation into the inferior vena cava (CAVI) with optimal medical therapy (OMT) in patients with severe TR. Here, we report details on the impact of CAVI on TR severity as well as right heart function and morphology. Methods and results: We randomized 28 patients with severe TR to CAVI (n = 14) with transfemoral implantation of an Edwards Sapien XT valve into the inferior vena cava or OMT (n = 14). Inclusion and exclusion criteria were based on anatomical and clinical parameters. Echocardiographic measurements were performed at baseline, at the first postoperative day and one, three, and twelve months after randomization. As proof of concept of an effective sealing of the inferior vena cava, we detected a significant decrease in systolic hepatic vein reflux volume (11.0 [6.2-21.9] mL vs 3.5 [0.6-8.5] mL,P = .016) and hepatic vein diameter (11.5 [10.0-14.8] mm vs 10.0 [9.3-11.8] mm,P = .034) at thirty-day follow-up. However, CAVI had no significant impact on TR, cardiac function, and morphology. Conclusions: Caval valve implantation significantly reduced systolic reflux into the hepatic veins but was not associated with an improvement in cardiac function, morphology, or TR severity