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This paper proposes a supervisory control structure for networked systems with time-varying delays. The control structure, in which a supervisor triggers the most appropriate controller from a multi-controller unit, aims at improving the closed-loop performance relative to what can be obtained using a single robust controller. Our analysis considers average(More)
This study examined the behaviour of the microbial population in an anaerobic reactor, in terms of changes in numbers of total bacterial community, autofluorescent methanogens, non-methanogens and morphology of the autofluorescent methanogens, using epifluorescence microscopy and microbiological enumeration techniques. A laboratory-scale, continuous(More)
— We consider the joint design of transmission schedules and controllers for networked control loops that use WirelessHART communication for sensor and actuator data. By parameterizing the design problem in terms of the sampling rate of the control loop, the co-design problem separates into two well-defined subproblems which admit optimal solutions:(More)
We consider a stochastic system where the communication between the controller and the actuator is triggered by a threshold-based rule. The communication is performed across an unreliable link that stochastically erases transmitted packets. To decrease the communication burden, and as a partial protection against dropped packets, the controller sends a(More)
— This paper studies minimum-energy packet forwarding policies for communicating sensor measurements from plant to controller over an unreliable multi-hop wireless network so as to guarantee that the optimal controller achieves a prespecified closed-loop performance. For fixed sampling interval, we demonstrate that the minimal linear-quadratic control loss(More)
We consider the joint design of packet forwarding policies and controllers for wireless control loops where sensor measurements are sent to the controller over an unreliable and energy-constrained multi-hop wireless network. For fixed sampling rate of the sensor, the co-design problem separates into two well-defined and independent subproblems: transmission(More)
— This paper develops a theoretical framework for quantifying the trade-off between communication cost and control performance in event-triggered control over lossy networks. We consider a system where the communication between the controller and actuator is dictated by a threshold-based event-triggering algorithm, and develop a Markov-chain model that(More)
The objective of this experimental study was to demonstrate the impact of trace metal supplementation, namely nickel (Ni), cobalt (Co) and molybdenum (Mo), on the methane yields obtained from batch mesophilic anaerobic digestion of maize silage as mono-substrate. The maize silage used in this experimental work initially lacked Ni and Co. Trace metal(More)