963 resultados para levers of control


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Controlling parenting is associated with child anxiety however the direction of effects remains unclear. The present study implemented a Latin-square experimental design to assess the impact of parental control on children’s anxious affect, cognitions and behaviour. A non-clinical sample of 24 mothers of children aged 4-5 years were trained to engage in (a) controlling and (b) autonomy-granting behaviours in interaction with their child during the preparation of a speech. When mothers engaged in controlling parenting behaviours, children made more negative predictions about their performance prior to delivering their speech and reported feeling less happy about the task, and this was moderated by child trait anxiety. In addition, children with higher trait anxiety displayed a significant increase in observed child anxiety in the controlling condition. The pattern of results was maintained when differences in mothers’ levels of negativity and habitual levels of control were accounted for. These findings are consistent with theories that suggest that controlling parenting is a risk factor in the development of childhood anxiety.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This paper considers the use of a discrete-time deadbeat control action on systems affected by noise. Variations on the standard controller form are discussed and comparisons are made with controllers in which noise rejection is a higher priority objective. Both load and random disturbances are considered in the system description, although the aim of the deadbeat design remains as a tailoring of reference input variations. Finally, the use of such a deadbeat action within a self-tuning control framework is shown to satisfy, under certain conditions, the self-tuning property, generally though only when an extended form of least-squares estimation is incorporated.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This paper discusses the use of multi-layer perceptron networks for linear or linearizable, adaptive feedback.control schemes in a discrete-time environment. A close look is taken at the model structure selected and the extent of the resulting parametrization. A comparison is made with standard, non-perceptron algorithms, e.g. self-tuning control, and it is shown how gross over-parametrization can occur in the neural network case. Because of the resultant heavy computational burden and poor controller convergence, a strong case is made against the use of neural networks for discrete-time linear control.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Using the integral manifold approach, a composite control—the sum of a fast control and a slow control—is derived for a particular class of non-linear singularly perturbed systems. The fast control is designed completely at the outset, thus ensuring the stability of the fast transients of the system and, furthermore, the existence of the integral manifold. A new method is then presented which simplifies the derivation of a slow control such that the singularly perturbed system meets a preselected design objective to within some specified order of accuracy. Though this approach is, by its very nature, ad hoc, the underlying procedure is easily extended to more general classes of singularly perturbed systems by way of three examples.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

An algorithm for solving nonlinear discrete time optimal control problems with model-reality differences is presented. The technique uses Dynamic Integrated System Optimization and Parameter Estimation (DISOPE), which achieves the correct optimal solution in spite of deficiencies in the mathematical model employed in the optimization procedure. A version of the algorithm with a linear-quadratic model-based problem, implemented in the C+ + programming language, is developed and applied to illustrative simulation examples. An analysis of the optimality and convergence properties of the algorithm is also presented.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Using a geometric approach, a composite control—the sum of a slow control and a fast control—is derived for a general class of non-linear singularly perturbed systems. A new and simpler method of composite control design is proposed whereby the fast control is completely designed at the outset. The slow control is then free to be chosen such that the slow integral manifold of the original system approximates a desired design manifold to within any specified order of ε accuracy.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Using a geometric approach, a composite control—the sum of a slow control and a fast control—is derived for a general class of non-linear singularly perturbed systems. A new and simpler method of composite control design is proposed whereby the fast control is completely designed at the outset. The slow control is then free to be chosen such that the slow integral manifold of the original system approximates a desired design manifold to within any specified order of ε accuracy.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The large pine weevil, Hylobius abietis, is a serious pest of reforestation in northern Europe. However, weevils developing in stumps of felled trees can be killed by entomopathogenic nematodes applied to soil around the stumps and this method of control has been used at an operational level in the UK and Ireland. We investigated the factors affecting the efficacy of entomopathogenic nematodes in the control of the large pine weevil spanning 10 years of field experiments, by means of a meta-analysis of published studies and previously unpublished data. We investigated two species with different foraging strategies, the ‘ambusher’ Steinernema carpocapsae, the species most often used at an operational level, and the ‘cruiser’ Heterorhabditis downesi. Efficacy was measured both by percentage reduction in numbers of adults emerging relative to untreated controls and by percentage parasitism of developing weevils in the stump. Both measures were significantly higher with H. downesi compared to S. carpocapsae. General linear models were constructed for each nematode species separately, using substrate type (peat versus mineral soil) and tree species (pine versus spruce) as fixed factors, weevil abundance (from the mean of untreated stumps) as a covariate and percentage reduction or percentage parasitism as the response variable. For both nematode species, the most significant and parsimonious models showed that substrate type was consistently, but not always, the most significant variable, whether replicates were at a site or stump level, and that peaty soils significantly promote the efficacy of both species. Efficacy, in terms of percentage parasitism, was not density dependent.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In this article, the prevailing official view of supervision as a regulatory instrument is examined as it applies to the social services sector in Sweden. The study is based on a comparison of the views expressed on the design of supervision as a regulatory instrument by two government commissions, the Supervision Commission and the Commission on Supervision within the Social Services (UTIS), and on the positions taken by the Government regarding the definitions of the concept of supervision proposed by these commissions. The view of supervision as a regulatory instrument expressed in these policy documents is analysed with the help of a theoretical framework describing the components, their functions and the governance characteristics of control systems. In the framework separate interrelated characteristics of the components are identified and summarized into two models of control systems. The analysis shows that supervision in the Swedish social services sector can be described in terms of both a disciplinary and non-disciplinary system. By its system theoretical basis and the identification of interrelated characteristics the study contributes to a broadened understanding of the construction and functions of supervision as a regulatory instrument and of how supervision within the Swedish social sector is meant to be designed.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Interpersonal trust is believed to influence the management and control of organisations in China. China's importance as a host country for foreign direct investments (FDIs) through multinational company subsidiaries (MNCs) and international joint ventures (IJVs) is growing rapidly. MNCs and INs located in China often employ local Chinese managers to control their subsidiaries or ventures. This makes it essential for designers of management control systems to have an understanding of the interpersonal trust-sensitive control behaviour of Chinese managers. One of the important aspects of control behaviour is how managers control their subordinates.

This paper examines the relationship between Chinese managers' trust in subordinates and their (Chinese managers') control behaviour towards the subordinates. On the basis of a questionnaire survey of a cohort of managers from Beijing, the study explores the effects of trust on the use of social controls, formal controls, and monitoring.

The findings of this study indicate that a manager's high (low) trust in a subordinate is associated with a low (high) level of monitoring, a high (high) level of social control and a high (low) level of perceived performance. The hypothesis that a superior's high (low) level of trust is associated with a low (high) level of reliance on formal controls was not supported. These findings, while indicative of control behaviour of Chinese managers in particular, also add to the growing academic literature on trust and control in general. In a practical sense, an
understanding of the trust-sensitive control behaviour of Chinese managers is particularly useful in designing and implementing effective control systems for international organisations operating in China.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Simulation provides a low cost method of initial testing of control for robotic swarms. The expansion of robotic swarms to heterogeneous environments drives the need to model cooperative operation in those environments. The Autonomous Control Engineering center at The University of Texas at San Antonio is investigating methods of simulation techniques and simulation environments. This paper presents results from adapting simulation tools for diverse environments.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The existing literature on parental control and children’s diets is confusing. The present paper reports two studies to explore an expanded conceptualisation of parental control with a focus on overt control which ‘can be detected by the child’ and covert control which ‘cannot be detected by the child’. In study 1, 297 parents of children aged between 4 and 11 completed a measure of overt control and covert control alongside ratings of their child’s snacking behaviour as a means to assess who uses either overt or covert control and how these aspects of parental control relate to a child’s snacking behaviour. The results showed that lighter parents and those with children perceived as heavier were more likely to use covert control and those from a higher social class were more likely to use overt control. Further, whilst greater covert control predicted a decreased intake of unhealthy snacks, greater overt control predicted an increased intake of healthy snacks. In study 2, 61 parents completed the same measure of overt and covert control alongside the three control subscales of the Child Feeding Questionnaire [Birch, L.L., Fisher, J.O., Grimm-Thomas, Markey, C.N., Sawyer, R. (2001). Confirmatory factor analysis of the Child Feeding Questionnaire: A measure of parental attitudes, beliefs and practices about child feeding and obesity proneness. Appetite, 36, 201–210] to assess degrees of overlap between these measures. The results showed that although these five measures of control were all positively correlated, the correlations between the new and existing measures indicated a maximum of 21% shared variance suggesting that covert and overt control are conceptually and statistically separate from existing measures of control. To conclude, overt and covert control may be a useful expansion of existing ways to measure and conceptualise parental control. Further, these constructs may differentially relate to snacking behaviour which may help to explain some of the confusion in the literature.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Analyses the mechanisms that cause thermal run-away in some materials. A control strategy was devised to provide effective temperature control independent of material characteristics. The set of control criteria derived from mathematical models allowed the control limits of a microwave processing system to calculated.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Challenges previous theory regarding the relationship between control and positive psychological health by finding a much greater role for control over peoples' internal emotions in positive psychological adjustment than was previously theorised. Presents a new tool for the measurement of control that realises the adaptive value of control over both the person's external environment and their internal psychological processes.