Filetype
State estimators are crucial components of anomaly detectors that are used to monitor cyber-physical systems. Many frequently-used state estimators are suscepti- ble to model risk as they rely critically on the availability of an accurate state-space model. Modeling errors make it more difficult to distinguish whether deviations from expected behavior are due to anomalies or simply a lack of knowl
In order to improve the energy efficiency in district heating networks and the comfort of their customers, these networks need to overcome the problem of unfair heat distribution under heat deficits. This paper introduces a new strategy to achieve this thermal fairness objective: it is lowcost in terms of communication and computation. The proposed approach is illustrated on a simulation example.
The MeerKAT radio telescope consists of 64 Gregorian-offset antennas located in the Karoo in the Northern Cape in South Africa. The antenna system consists of multiple subsystems working collaboratively to form a cohesive instrument capable of operating in multiple modes for defined science cases. We focus on the channelizing subsystem (F-engine), the correlation subsystem (X-engine), and the beam
A project about why and how we have smartphones, how we use them and what the future is, resulting in a new product category, the Pocket tablet. Today's mobile communication devices offer us tremendous opportunities to move our work, socialization and entertainment anywhere, to the bus, to the car and even into line at the grocery store. They give us the power of a computer and the internet r
In this paper we consider the problem of outlier removal for large scale multiview reconstruction problems. An efficient and very popular method for this task is RANSAC. However, as RANSAC only works on a subset of the images, mismatches in longer point tracks may go ndetected. To deal with this problem we would like to have, as a post processing step to RANSAC, a method that works on the entire (
This thesis explores methods for solving the structure-and-motion problem in computer vision, the recovery of three-dimensional data from a series of two-dimensional image projections. The first paper investigates an alternative state space parametrization for use with the Kalman filter approach to simultaneous localization and mapping, and shows it has superior convergence properties compared wit
We consider the problem of localizing a novel image in a large 3D model. In principle, this is just an instance of camera pose estimation, but the scale introduces some challenging problems. For one, it makes the correspondence problem very difficult and it is likely that there will be a significant rate of outliers to handle. In this paper we use recent theoretical as well as technical advances t
Embedded systems often operate in so variable con- ditions that design can only be carried out for some worst-case scenario. This leads to over-provisioned resources, and undue power consumption. Feedback control is an effective (and not yet fully explored) way to tailor resource usage online, thereby making the system behave and consume as if it was optimized for each specific utilization case. A
In this paper, we explore positivity preserving model reduction. The reduction is performed by truncating the states of the original system without balancing in the classical sense. This may result in conservatism, however, this way the physical meaning of the individual states is preserved. The reduced order models can be obtained using simple matrix operations or using distributed optimization m
To date, not that much. Improvements are possible, but some system-theoretically grounded re-design is necessary. We discuss the matter based on our experience, and as a consequence, we come to distilling some design clues and research directions.
We study an optimal control problem for a simple transportation model on a path graph. We give a closed form solution for the optimal controller, which can also account for planned disturbances using feed-forward. The optimal controller is highly structured, which allows the controller to be implemented using only local communication, conducted through two sweeps through the graph.
When deploying networked computing-based applications, proper resource management of the server-side resources is essential for maintaining quality of service and cost efficiency. The work presented in this thesis is based on six papers, all investigating problems that relate to resource management of server-based systems. Using a queueing system approach we model the performance of a database sys
This thesis addresses challenges in increasing the robustness of cloud-deployed applications and services to unexpected events and dynamic workloads. Without precautions, hardware failures and unpredictable large traffic variations can quickly degrade the performance of an application due to mismatch between provisioned resources and capacity needs. Similarly, disasters, such as power outages and
Cloud computing has dramatically simplified the deployment of new software and, indeed, the number of applications that are hosted by cloud providers every day is increasing. The data center owner should provide computing capacity to a set of customers, each of them powering up and down virtual machines dynamically, to handle variations in the incoming requests. Cloud providers, however, should al
