72 resultados para distributed control and estimation

em Deakin Research Online - Australia


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In this paper we address the problem of decentralized and robust linear filtering for target tracking using networks of (radar) sensors taking nonlinear range and bearing measurements. The algorithm introduced in this paper permits efficient data fusion from multiple sensors through a summation style fusion architecture. Moreover, we prove that the state estimation error for the linear filtering algorithm is bounded.

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In this paper, we describe SpeedNet, a GSM network variant which resembles an ad hoc wireless mobile network where base stations keep track of the velocities of mobile users (cars). SpeedNet is intended to track mobile users and their speed passively for both speed policing and control of traffic. The speed of the vehicle is controlled in a speed critical zone by means of an electro-mechanical control system, suitably referred to as VVLS (Vehicular Velocity Limiting System). VVLS is mounted on the vehicle and responds to the command signals generated by the base station. It also determines the next base station to handoff, in order to improve the connection reliability and bandwidth efficiency of the underlying network. Robust Extended Kalman Filter (REKF) is used as a passive velocity estimator of the mobile user with the widely used proportional and integral controller speed control. We demonstrate through simulation and analysis that our prediction algorithm can successfully estimate the mobile user’s velocity with low system complexity as it requires two closest mobile base station measurements and also it is robust against system uncertainties due to the inherent deterministic nature in the mobility model.

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While control-related cognitions have often been implicated in discussions of Obsessive Compulsive Disorder (OCD), empirical investigations of the relationship between control-constructs and OCD symptoms have been relatively limited. In this article it was hypothesized that OCD symptoms may be linked with a higher desire to control (DC), but a lower sense of control (SC) over the self and environment, leading to motivation for compulsive symptoms. This hypothesis was investigated in an analogue population, using regression analyses controlling for depression and anxiety. Consistent with predictions, it was found that higher levels of DC and lower levels of SC were associated with higher levels of OCD-related beliefs and symptoms. While control cognitions were linked with the OCD-related beliefs of perfectionism and the over-estimation of threat, they did not relate to cognitions concerning the importance of/need to control thoughts. With respect to specific OCD-symptoms, control cognitions were most strongly related to contamination obsessions/washing compulsions. Implications for theory and treatment are discussed.

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Smart grid constrained optimal control is a complex issue due to the constant growth of grid complexity and the large volume of data available as input to smart device control. In this context, traditional centralized control paradigms may suffer in terms of the timeliness of optimization results due to the volume of data to be processed and the delayed asynchronous nature of the data transmission. To address these limits of centralized control, this paper presents a coordinated, distributed algorithm based on distributed, local controllers and a central coordinator for exchanging summarized global state information. The proposed model for exchanging global state information is resistant to fluctuations caused by the inherent interdependence between local controllers, and is robust to delays in information exchange. In addition, the algorithm features iterative refinement of local state estimations that is able to improve local controller ability to operate within network constraints. Application of the proposed coordinated, distributed algorithm through simulation shows its effectiveness in optimizing a global goal within a complex distribution system operating under constraints, while ensuring network operation stability under varying levels of information exchange delay, and with a range of network sizes.

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Microgrids are currently controlled independently, according to local requirements and aims, often based on local control strategies and without coordination with other microgrids [1], [2]. However, it is anticipated that future sub-transmission and distribution systems will be composed of several interconnected microgrids and form a complex elec-tric network. Interconnecting together multiple microgrids can lead to undesirable dynamic behaviors, which have not been adequately examined so far. In particular, this paper dis-cusses power oscillations arising from multiple interconnected microgrids and proposes a control scheme based on a robust distributed control approach.

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Objectives: To examine whether the subjective quality of life (QOL) of elderly people is held under homeostatic control, and to investigate the role of perceived control and dispositional optimism in the maintenance of subjective QOL.
Method: 100 older people (M=75.6 years) and a control group of 107 younger people (M=20.1 years) completed a self-report survey.
Results: Both groups had a level of subjective QOL within the normal range. The older group reported higher levels of secondary control and optimism, but similar levels of primary control, as the younger group. Primary control and optimism predicted subjective QOL for both groups. Secondary control was a significant predictor (or the younger group, however it was only marginally significant for the older group. Optimism accounted for the most subjective QOL variance for both groups.
Conclusions: The finding that the subjective QOL of the older group lay within the normative range supports the proposal that their subjective QOL is being successfully maintained under bomeostatic control. However, they appear to have an increased reliance on secondary control. The fact that dispositional optimism captures the predictive variance of perceived control, is an important finding adding to the understanding of subjective QOL maintenance.

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While situational factors such as high workloads have been found to be predictive of burnout, not all people in the same work context develop burnout. This suggests that individual factors are implicated in susceptibility to burnout. We investigated the relationships between care type (acute/chronic), neuroticism, control (primary/secondary), and symptoms of burnout (exhaustion, cynicism, and reduced professional efficacy) amongst 21 chronic care nurses and 83 acute care nurses working in a public hospital in regional Australia. Similar levels of burnout symptomatology and neuroticism were found in each group of nurses, and neuroticism was found to be associated with exhaustion, cynicism, and reduced professional efficacy in the total sample of nurses. Our prediction that primary control would protect against burnout symptoms in acute care nurses was supported only for professional efficacy, and the prediction that secondary control would protect against burnout in chronic care nurses was not supported.

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Teachers are among those working longer hours more than ever before. the implications of these long hours on teachers' health, through work-family conflict, control over hours worked and organisational support were investigated. 120 teachers, of whom 91 (59.3% female) reported
working in excess of 37 1/2 hours in the week prior, participated in the study. Long hours, work-family conflict, control and organisational support, explained 69% of the variance in health. There was no direct effect of long worked hours on health however long hours did have a direct impact on work-family conflict, organisational support, and control and, through
these, teachers' health. Work-family conflict exerted a direct negative impact on health. These findings are discussed in individual and organisational tenns.

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Over the last m'o decades, university systems world-wide have been subject to government initiated, top-down restructures in the name of greater effectiveness, accountability and quality. Within this timefrome, government interest in university teaching has increased, and innovation and responsiveness in teaching have been increasingly prioritised by both government and university policies. AcademiC interest in the teaching has also increased. and much research and discussion has focused on defining teaching as a source of scholarship and expounding its role in the promotion of innovation, and in the recognition and rewarding of teaching work. In this paper, I draw on a study of academics' views, which I have reported at previous AARE conferences and elsewhere, to raise questions about recent and ongoing developments in the work environment of university educators.l raise the possibility that systems and processes whose express purpose is to facilitate and support university educators' efforts to improve teaching are, in fact. inhibiting innovative practice by institutionalising an aversion to risk that is anathema to innovation.

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In this paper, we describe SpeedNet, a GSM network variant which resembles an ad hoc wireless mobile network where base stations (possibly other vehicles in the network) keep track of the velocities of mobile users (cars). SpeedNet is intended to track mobile users and their speed passively for both speed policing and control of traffic. The speed of the vehicle is controlled in a speed critical zone by means of an electro-mechanical control system, suitably referred to as VVLS (vehicular velocity limiting system). VVLS is mounted in the vehicle and responds to the command signals generated by the base station. It also determines the next basestation to handoff, in order to improve the connection reliability and bandwidth efficiency of the underlying network. Robust extended Kalman filter (REKF) is used as a passive velocity estimator of the mobile user with the widely used proportional and integral controller speed control. We demonstrate through simulation and analysis that our prediction algorithm can successfully estimate the mobile users velocity with low system complexity as it requires two closet mobile-base station measurement and also it is robust against system uncertainties due to the inherent deterministic nature in the mobility model.

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Purpose
To examine the role of both positive and negative styles of self-control, and gender-role stereotypes in binge eating and problem drinking.

Method
Participants were 428 adolescent boys and 555 girls from predominantly Anglo-Australian backgrounds who attended regional state schools in New South Wales, Australia. Students completed standardized questionnaires that assessed problem drinking, binge eating, self-control styles, and identification with gender-role stereotypes. ANOVA and post hoc Tukey tests were conducted to examine differences among adolescents who reported problems in binge eating, drinking, and both domains.

Results
Adolescents who reported eating and drinking problems also reported a high negative and a low positive sense of self-control coupled with self-identification with the traits that typically describe negative dimensions of gender-role stereotypes. Regardless of gender, problem drinking was mainly related to traits of negative masculinity (bossy, noisy aggressive, etc.) whereas binge eating was mainly related to negative femininity (shy, needs approval from others, etc.). Participants who reported eating and drinking symptoms recorded low scores on positive control, high scores on negative control, and also high scores on the negative dimensions of masculinity and femininity.

Summary
A negative and passive style of self-control coupled with an identification with negative dimensions of gender summarizes the type of self-regulation that is implicated in both binge eating and problem drinking, and co-morbid symptoms. There is a need for interventions working toward a more balanced gender self-concept and a positive sense of self-control.

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An anycast flow is a flow that can be connected to any one of the members in a group of designated (replicated) servers (called anycast group). In this paper, we derive a set of formulas for calculating the end-to-end delay bound for the anycast flows and present novel admission control algorithms for anycast flows with real-time constraints. Given such an anycast group, our algorithms can effectively select the paths for anycast flows' admission and connection based on the least end-to-end delay bounds evaluated. We also present a parallel admission control algorithm that can effectively calculate the available paths with a short delay bound for different destinations in the anycast group so that a best path with the shortest delay bound can be chosen.