153 resultados para Random Allocation


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Although some research suggests that dog-assisted therapy may be beneficial for people with dementia living in residential aged care facilities, the intervention has not been adequately investigated. To address this shortcoming, we conducted a randomized controlled trial of dog-assisted therapy versus a human-therapist-only intervention for this population. Fifty-five residents with mild to moderate dementia living in three Australian residential aged care facilities completed an 11-week trial of the interventions. Allocation to the intervention was random and participants completed validated measures of mood, psychosocial functioning, and quality of life (QOL), both prior to and following the intervention. No adverse events were associated with the dog-assisted intervention, and following it participants who had worse baseline depression scores demonstrated significantly improved depression scores relative to participants in the human-therapist-only intervention. Participants in the dogassisted intervention also showed significant improvements on a measure of QOL in one facility compared with those in the human-therapist-only group (although worse in another facility that had been affected by an outbreak of gastroenteritis). This study provides some evidence that dog-assisted therapy may be beneficial for some residents of aged care facilities with dementia.

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Earthwork planning has been considered in this article and a generic block partitioning and modelling approach has been devised to provide strategic plans of various levels of detail. Conceptually this approach is more accurate and comprehensive than others, for instance those that are section based. In response to environmental concerns the metric for decision making was fuel consumption and emissions. Haulage distance and gradient are also included as they are important components of these metrics. Advantageously the fuel consumption metric is generic and captures the physical difficulties of travelling over inclines of different gradients, that is consistent across all hauling vehicles. For validation, the proposed models and techniques have been applied to a real world road project. The numerical investigations have demonstrated that the models can be solved with relatively little CPU time. The proposed block models also result in solutions of superior quality, i.e. they have reduced fuel consumption and cost. Furthermore the plans differ considerably from those based solely upon a distance based metric thus demonstrating a need for industry to reflect upon their current practices.

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This thesis presents an analysis of the resource allocation problem in Orthogonal Frequency Division Multiplexing based multi-hop wireless communications systems. The study analyzed the tractable nature of the problem and designed several heuristic and fairness-aware resource allocation algorithms. These algorithms are fast and efficient and therefore can improve power management in wireless systems significantly.

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The purpose of this paper is to document and explain the allocation of takeover purchase price to identifiable intangible assets (IIAs), purchased goodwill, and/or target net tangible assets in an accounting environment unconstrained with respect to IIA accounting policy choice. Using a sample of Australian acquisitions during the unconstrained accounting environment from 1988 to 2004, we find the percentage allocation of purchase price to IIAs averaged 19.09%. The percentage allocation to IIAs is significantly positively related to return on assets and insignificantly related to leverage, contrary to opportunism. Efficiency suggests an explanation: profitable firms acquire and capitalise a higher percentage of IIAs in acquisitions. The target's investment opportunity set is significantly positively related to the percentage allocation to IIAs, consistent with information-signalling. The paper contributes to the accounting policy choice literature by showing how Australian firms make the one-off accounting policy choice in regards allocation of takeover purchase price (which is often a substantial dollar amount to) in an environment where accounting for IIAs was unconstrained.

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The transmission path from the excitation to the measured vibration on the surface of a mechanical system introduces a distortion both in amplitude and in phase. Moreover, in variable speed conditions, the amplification/attenuation and the phase shift, due to the transfer function of the mechanical system, varies in time. This phenomenon reduces the effectiveness of the traditionally tachometer based order tracking, compromising the results of a discrete-random separation performed by a synchronous averaging. In this paper, for the first time, the extent of the distortion is identified both in the time domain and in the order spectrum of the signal, highlighting the consequences for the diagnostics of rotating machinery. A particular focus is given to gears, providing some indications on how to take advantage of the quantification of the disturbance to better tune the techniques developed for the compensation of the distortion. The full theoretical analysis is presented and the results are applied to an experimental case.

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Background Post-stroke recovery is demanding. Increasing studies have examined the effectiveness of self-management programs for stroke survivors. However no systematic review has been conducted to summarize the effectiveness of theory-based stroke self-management programs. Objectives The aim is to present the best available research evidence about effectiveness of theory-based self-management programs on community-dwelling stroke survivors’ recovery. Inclusion criteria Types of participants All community-residing adults aged 18 years or above, and had a clinical diagnosis of stroke. Types of interventions Studies which examined effectiveness of a self-management program underpinned by a theoretical or conceptual framework for community-dwelling stroke survivors. Types of studies Randomized controlled trials. Types of outcomes Primary outcomes included health-related quality of life and self-management behaviors. Secondary outcomes included physical (activities of daily living), psychological (self-efficacy, depressive symptoms), and social outcomes (community reintegration, perceived social support). Search Strategy A three-step approach was adopted to identify all relevant published and unpublished studies in English or Chinese. Methodological quality The methodological quality of the included studies was assessed using the Joanna Briggs Institute critical appraisal checklist for experimental studies. Data Collection A standardized JBI data extraction form was used. There was no disagreement between the two reviewers on the data extraction results. Data Synthesis There were incomplete details about the number of participants and the results in two studies, which makes it impossible to perform meta-analysis. A narrative summary of the effectiveness of stroke self-management programs is presented. Results Three studies were included. The key issues of concern in methodological quality included insufficient information about random assignment, allocation concealment, reliability and validity of the measuring instruments, absence of intention-to-treat analysis, and small sample sizes. The three programs were designed based on the Stanford Chronic Disease Self-management program and were underpinned by the principles of self-efficacy. One study showed improvement in the intervention group in family and social roles three months after program completion, and work productivity at six months as measured by the Stroke Specific Quality of Life Scale (SSQOL). The intervention group also had an increased mean self-efficacy score in communicating with physicians six months after program completion. The mean changes from baseline in these variables were significantly different from the control group. No significant difference was found in time spent in aerobic exercise between the intervention and control groups at three and six months after program completion. Another study, using SSQOL, showed a significant interaction effect by treatment and time on family roles, fine motor tasks, self-care, and work productivity. However there was no significant interaction by treatment and time on self-efficacy. The third study showed improvement in quality of life, community participation, and depressive symptoms among the participants receiving the stroke self-management program, Stanford Chronic Disease Self-management program, or usual care six months after program completion. However, there was no significant difference between the groups. Conclusions There is inconclusive evidence about the effectiveness of theory-based stroke self-management programs on community-dwelling stroke survivors’ recovery. However the preliminary evidence suggests potential benefits in improving stroke survivors’ quality of life and self-efficacy.

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Research suggests that the length and quality of police-citizen encounters affect policing outcomes. The Koper Curve, for example, shows that the optimal length for police presence in hot spots is between 14 and 15 minutes, with diminishing returns observed thereafter. Our study, using data from the Queensland Community Engagement Trial (QCET), examines the impact of encounter length on citizen perceptions of police performance. QCET involved a randomised field trial, where 60 random breath test (RBT) traffic stop operations were randomly allocated to an experimental condition involving a procedurally just encounter or a business-as-usual control condition. Our results show that the optimal length of time for procedurally just encounters during RBT traffic stops is just less than 2 minutes. We show, therefore, that it is important to encourage and facilitate positive police–citizen encounters during RBTat traffic stops, while ensuring that the length of these interactions does not pass a point of diminishing returns.

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We construct two efficient Identity-Based Encryption (IBE) systems that admit selective-identity security reductions without random oracles in groups equipped with a bilinear map. Selective-identity secure IBE is a slightly weaker security model than the standard security model for IBE. In this model the adversary must commit ahead of time to the identity that it intends to attack, whereas in an adaptive-identity attack the adversary is allowed to choose this identity adaptively. Our first system—BB1—is based on the well studied decisional bilinear Diffie–Hellman assumption, and extends naturally to systems with hierarchical identities, or HIBE. Our second system—BB2—is based on a stronger assumption which we call the Bilinear Diffie–Hellman Inversion assumption and provides another approach to building IBE systems. Our first system, BB1, is very versatile and well suited for practical applications: the basic hierarchical construction can be efficiently secured against chosen-ciphertext attacks, and further extended to support efficient non-interactive threshold decryption, among others, all without using random oracles. Both systems, BB1 and BB2, can be modified generically to provide “full” IBE security (i.e., against adaptive-identity attacks), either using random oracles, or in the standard model at the expense of a non-polynomial but easy-to-compensate security reduction.

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We describe a short signature scheme that is strongly existentially unforgeable under an adaptive chosen message attack in the standard security model. Our construction works in groups equipped with an efficient bilinear map, or, more generally, an algorithm for the Decision Diffie-Hellman problem. The security of our scheme depends on a new intractability assumption we call Strong Diffie-Hellman (SDH), by analogy to the Strong RSA assumption with which it shares many properties. Signature generation in our system is fast and the resulting signatures are as short as DSA signatures for comparable security. We give a tight reduction proving that our scheme is secure in any group in which the SDH assumption holds, without relying on the random oracle model.

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In this paper, we address the control design problem of positioning of over-actuated marine vehicles with control allocation. The proposed design is based on a combined position and velocity loops in a multi-variable anti-windup implementation together with a control allocation mapping. The vehicle modelling is considered with appropriate simplifications related to low-speed manoeuvring hydrodynamics and vehicle symmetry. The control design is considered together with a control allocation mapping. We derive analytical tuning rules based on requirements of closed-loop stability and performance. The anti- windup implementation of the controller is obtained by mapping the actuator-force constraint set into a constraint set for the generalized forces. This approach ensures that actuation capacity is not violated by constraining the generalized control forces; thus, the control allocation is simplified since it can be formulated as an unconstrained problem. The mapping can also be modified on-line based on actuator availability to provide actuator-failure accommodation. We provide a proof of the closed-loop stability and illustrate the performance using simulation scenarios for an open-frame underwater vehicle.

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A control allocation system implements a function that maps the desired control forces generated by the vehicle motion controller into the commands of the different actuators. In this article, a survey of control allocation methods for over-actuated underwater vehicles is presented. The methods are applicable for both surface vessels and underwater vehicles. The paper presents a survey of control allocation methods with focus on mathematical representation and solvability of thruster allocation problems. The paper is useful for university students and engineers who want to get an overview of state-of-the art control allocation methods as well as advance methods to solve more complex problems.

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Planning techniques for large scale earthworks have been considered in this article. To improve these activities a “block theoretic” approach was developed that provides an integrated solution consisting of an allocation of cuts to fills and a sequence of cuts and fills over time. It considers the constantly changing terrain by computing haulage routes dynamically. Consequently more realistic haulage costs are used in the decision making process. A digraph is utilised to describe the terrain surface which has been partitioned into uniform grids. It reflects the true state of the terrain, and is altered after each cut and fill. A shortest path algorithm is successively applied to calculate the cost of each haul, and these costs are summed over the entire sequence, to provide a total cost of haulage. To solve this integrated optimisation problem a variety of solution techniques were applied, including constructive algorithms, meta-heuristics and parallel programming. The extensive numerical investigations have successfully shown the applicability of our approach to real sized earthwork problems.

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Techniques for evaluating and selecting multivariate volatility forecasts are not yet understood as well as their univariate counterparts. This paper considers the ability of different loss functions to discriminate between a set of competing forecasting models which are subsequently applied in a portfolio allocation context. It is found that a likelihood-based loss function outperforms its competitors, including those based on the given portfolio application. This result indicates that considering the particular application of forecasts is not necessarily the most effective basis on which to select models.