This work presents a strategy to minimise the network usage and the energy consumption of wireless battery-powered sensors in the observer problem over networks. The sensor nodes implement a periodic send-on-delta approach, sending new measurements when a measure deviates considerably from the previous sent one. The estimator node implements a jump observer whose gains are computed offline and depend on the combination of available new measurements. We bound the estimator performance as a function of the sending policies and then state the design procedure of the observer under fixed sending thresholds as a semidefinite programming problem. We address this problem first in a deterministic way and, to reduce conservativeness, in a stochastic one after obtaining bounds on the probabilities of having new measurements and applying robust optimisation problem over the possible probabilities using sum of squares decomposition. We relate the network usage with the sending thresholds and propose an iterative procedure for the design of those thresholds, minimising the network usage while guaranteeing a prescribed estimation performance. Simulation results and experimental analysis show the validity of the proposal and the reduction of network resources that can be achieved with the stochastic approach. 相似文献
The Journal of Supercomputing - There exist problems in the field of digital signal processing, such as filtering of acoustic signals that require processing a large amount of data in real time.... 相似文献
The Aznalcóllar tailings pond failure (1998) is regarded as one of the severe ecological mine disasters ever reported. The spill of the mine tailings affected more than 60 km of the Agrio and Guadiamar rivers and caused major environmental damage. Despite the event being well-documented with more than 400 scientific publications, including two special issues and two reviews, several hydraulic uncertainties and inconsistencies remain. This paper conducts a state-of-the-art review of the most relevant hydraulic aspects of the mine disaster. It addresses the pond and fluid characteristics, the break type, the breaking time, the flow propagation, the volume potentially stored and subsequently spilled, area dimensions affected by the spill, and the morphological changes generated in the river and riverbanks caused by the spill, and later on by the restoration activities. Several discrepancies and plenty of controversial data have been unearthed that may affect general understanding of the event. In addition, new data is introduced and analysed applying photointerpretation and digital terrain analysis techniques, aiming to derive in essential hydraulic parameters. The most important findings are that the spill could have had a volume about 11.5 hm3, affecting about 86.7 km of river length, twice the most referenced values in the literature, and that applied restoration activities have substantially modified the hydro-sedimentary processes of the affected system. Additionally, a first video observation-based classification reveals that the fluid behaved more like a highly concentrated sediment-laden flow than like a mud flow.
OBJECTIVE: The aim of the present study was to determine the extent to which mother-child interactional patterns in high- and low-risk (for child physical abuse) mothers were similar to patterns observed in physically abusive parents. METHOD: Ten high-risk and 10 demographically similar low-risk mother-child dyads were studied. Trained observers coded maternal-child interaction patterns in the home during five 1-hour periods using the Standardized Observation Codes system. RESULTS: As expected, high-risk mothers made fewer neutral approaches to their children, displayed more negative behaviors toward their children, and made more indiscriminant responses to their children's prosocial behavior. Expected risk group differences were not found in the number of neutral instructions or positive responses, albeit the proportion of positive responses out of the total number of positive and negative responses was higher for low-risk mothers. After control for educational differences, risk group differences remained in the rates of neutral approaches and the number of indiscriminant behaviors made in response to children's prosocial behaviors. CONCLUSIONS: The observational data indicated that high-risk mothers display some behaviors similar to those observed in physically abusive mothers. The finding that high-risk mothers made more indiscriminate or noncontingent responses when reacting to their children's prosocial behavior is consistent with a coercive model of child physical abuse. 相似文献
The Journal of Supercomputing - The use of synchronization mechanisms in multithreaded applications is essential on shared-memory multi-core architectures. However, debugging parallel applications... 相似文献