Robust fault estimation for wind turbine energy via hybrid systems.

The rapid development of modern wind turbine technology has led to increasing demand for improving system reliability and practical concern for robust fault monitoring scheme. This paper presents the investigation of a 5 MW Dynamic Wind Turbine Energy System that was designed to sustain condition monitoring and fault diagnosis with the goal of improving the reliability operations of universal practical control systems. A hybrid stochastic technique is proposed based on an augmented observer combined with eigenstructure assignment for the parameterisation and the genetic algorithm (GA) optimisation to address the attenuation of uncertainty mostly generated by disturbances. Scenarios-based are employed to explore sensor and actuator faults that have direct and indirect impacts on modern wind turbine system, based on monitoring components that are prone to malfunction. The analysis is aimed to determine the effect of concerned simulated faults from uncertainty in respect to environmental disturbances mostly challenged in real-world operations. The efficiency of the proposed approach will improve the reliability performance of wind turbine system states and diagnose uncertain faults simultaneously. The simulation outcomes illustrate the robustness of the dynamic turbine systems with a diagnostic performance to advance the practical solutions for improving reliable systems.N/

The evolution of inverted magnetic fields through the inner heliosphere

Local inversions are often observed in the heliospheric magnetic field (HMF), but their origins and evolution are not yet fully understood.Parker Solar Probe has recently observed rapid, Alfvénic, HMF inversions in the inner heliosphere, known as ‘switchbacks’, which have been interpreted as the possible remnants of coronal jets. It has also been suggested that inverted HMF may be produced by near-Sun interchange reconnection; a key process in mechanisms proposed for slow solar wind release. These cases suggest that the source of inverted HMF is near the Sun, and it follows that these inversions would gradually decay and straighten as they propagate out through the heliosphere. Alternatively, HMF inversions could form during solar wind transit, through phenomena such velocity shears, draping over ejecta, or waves and turbulence. Such processes are expected to lead to a qualitatively radial evolution of inverted HMF structures. Using Helios measurements spanning 0.3–1 AU, we examine the occurrence rate of inverted HMF, as well as other magnetic field morphologies, as a function of radial distance r, and find that it continually increases. This trend may be explained by inverted HMF observed between 0.3–1 AU being primarily driven by one or more of the above in-transit processes, rather than created at the Sun. We make suggestions as to the relative importance of these different processes based on the evolution of the magnetic field properties associated with inverted HMF. We also explore alternative explanations outside of our suggested driving processes which may lead to the observed trend

Advance care plans and hospitalized frail older adults: a systematic review.

INTRODUCTION: Frail older people are known to have low rates of advance care planning (ACP). Many frail patients prefer less aggressive treatment, but these preferences are often not known or respected. Frail patients often have multiple hospital admissions, potentially providing opportunities for ACP. OBJECTIVE: To systematically review the literature concerning ACP with frail older people in the acute hospital, with particular reference to: (1) Does ACP improve outcomes? (2) What are the views of patients, relatives and healthcare professionals regarding ACP? (3) Does ACP currently occur? (4) What are the facilitators and barriers to ACP? DESIGN: Systematic literature review and narrative synthesis. Electronic search of MEDLINE, CINAHL, ASSIA, PsycINFO and Embase databases from January 1990 to May 2019 inclusive. Studies in the acute setting of populations with a mean age >75 years, not focused on a disease-specific terminal condition were included. RESULTS: 16 133 articles were retrieved, 14 met inclusion criteria. No studies used an objective measure of frailty. One randomised controlled trial (RCT) found that ACP improves outcomes for older patients. Although 74%-84% of capacitous older inpatients are receptive to ACP, rates of ACP are 0%-5%; the reasons for this discrepancy have been little studied. The nature of ACP in clinical practice is unknown thus the extent to which it reflects the RCT intervention cannot be assessed. The outcomes that are important to patients are poorly understood and family and physician experiences have not been explored. CONCLUSIONS: A better understanding of this area could help to improve end-of-life care for frail older people. PROSPERO REGISTRATION NUMBER: CRD42017080246

Assessed, student-led dialogic interaction: a Bakhtinian analysis of a case study of undergraduate history seminars

A Bakhtinian theoretical framework throws fresh light on higher education assessment, dialogue and classroom dynamics, demonstrating that assessed, student-led seminars can have a powerfully positive effect on student learning. The case study comprised of a well-established programme of seminars in a university history department. These seminars, which are regarded as innovative, have three distinctive features: they are assessed; they contain dialogic interaction; and they are student-led. This qualitative study investigating the effects of the seminars on student learning employed interviews with tutors and students, and observations of seminars. A holistic picture has been created which takes account of the socio-ideological context of the seminars, the socio-linguistic structures which constituted the actual interaction and the participants’ perspectives. A Bakhtinian analysis was applied to empirical data and revealed that it is when three conditions are in place that the potential for dialogic learning is enhanced. Firstly, assessment directs students’ activity amplifying their learning experience. Secondly, the use of different types of dialogue enables students to assimilate new ideas. Thirdly, through peer facilitation and leadership of the seminars, along with other structuring devices, the power dynamics of the classes remain open and fluid and the tutor is prevented from unwittingly suppressing active student involvement. In these conditions, it is argued, students are able to engage actively with the material in-hand resulting in a richer learning experience

Predicting the effect of the solar wind on the ultra-low frequency plasma waves driving Earth’s radiation belts

Earth’s radiation belts represent a hazardous environment for spacecraft. Ultra-low frequency (ULF, 1-20 mHz) plasma waves in Earth’s magnetosphere are responsible for the bulk transport and energisation of energetic electrons via radial diffusion. These large-scale waves are strongly driven by the solar wind and need better characterisation in order to improve radial diffusion coefficients in radiation belt diffusion models; current parameterisations of radial diffusion coefficients vary by orders of magnitude. However, selecting solar wind properties on which to base an empirical model of ULF occurrence is difficult due to the complicated interparameter relationships between solar wind properties which mask their relationship to ULF wave power. Using fifteen years of solar wind and ground-based magnetometer measurements, we identify three non-derived solar wind properties that are causally correlated to dayside ULF wave power at a single representative frequency and station. Solar wind speed vsw, southward interplanetary magnetic field Bz < 0 and summed perturbations in proton number density δN p are all found to contribute significantly to ULF wave power. The corresponding driving mechanisms - magnetopause deformation processes - are discussed and it is concluded that they are highly interrelated. With these three parameters, an empirical model for ground-based ULF wave power is developed and tested across a range of frequencies, magnetic latitudes and azimuthal angles throughout the magnetosphere. Model output is a probability distribution instead of a single deterministic value; this probabilistic approach will allow the uncertainty in radial diffusion coefficients to be quantified. This model can be used in two ways to reproduce wave power; by sampling from conditional probability distribution functions or by using the mean (expectation) values. A method is derived to test the quality of the parameterisation and the ability of the model to reproduce ULF wave power time series. Sampling is a better method for reproducing power over an extended time period as it retains the same overall distribution, while mean values predict the power in a time series better than the assumption that power persists from the preceding hour. Other sources of uncertainty in radial diffusion coefficients are reviewed. Although this wave model is designed principally for the goal of improved radial diffusion coefficients to include in outer radiation belt diffusion based modelling, we give examples to illustrate how it may be used to investigate the occurrence of ULF waves throughout the magnetosphere and hence the physics of ULF wave generation and propagation

Particle-in-cell experiments examine electron diffusion by whistler-mode waves: 1. Benchmarking with a cold plasma

Using a particle-in-cell code, we study the diffusive response of electrons due to wave particle interactions with whistler-mode waves. The relatively simple configuration of field-aligned waves in a cold plasma is used in order to benchmark our novel method, and to compare with previous works that used a different modelling technique. In this boundary-value problem, incoherent whistler-mode waves are excited at the domain boundary, and then propagate through the ambient plasma. Electron diffusion characteristics are directly extracted from particle data across all available energy and pitch-angle space. The ‘nature’ of the diffusive response is itself a function of energy and pitch-angle, such that the rate of diffusion is not always constant in time. However, after an initial transient phase, the rate of diffusion tends to a constant, in a manner that is consistent with the assumptions of quasilinear diffusion theory. This work establishes a framework for future investigations on the nature of diffusion due to whistler-mode wave-particle interactions, using particle-in-cell numerical codes with driven waves as boundary value problems

Feasibility trial evaluation of a physical activity and screen-viewing course for parents of 6 to 8 year-old children : Teamplay

Background: Many children spend too much time screen-viewing (watching TV, surfing the internet and playing video games) and do not meet physical activity (PA) guidelines. Parents are important influences on children’s PA and screen-viewing (SV). There is a shortage of parent-focused interventions to change children’s PA and SV. Methods: Teamplay was a two arm individualized randomized controlled feasibility trial. Participants were parents of 6–8 year old children. Intervention participants were invited to attend an eight week parenting program with each session lasting 2 hours. Children and parents wore an accelerometer for seven days and minutes of moderate-to-vigorous intensity PA (MVPA) were derived. Parents were also asked to report the average number of hours per day that both they and the target child spent watching TV. Measures were assessed at baseline (time 0) at the end of the intervention (week 8) and 2 months after the intervention had ended (week 16). Results: There were 75 participants who provided consent and were randomized but 27 participants withdrew post-randomization. Children in the intervention group engaged in 2.6 fewer minutes of weekday MVPA at Time 1 but engaged in 11 more minutes of weekend MVPA. At Time 1 the intervention parents engaged in 9 more minutes of weekday MVPA and 13 more minutes of weekend MVPA. The proportion of children in the intervention group watching ≥ 2 hours per day of TV on weekend days decreased after the intervention (time 0 = 76%, time 1 = 39%, time 2 = 50%), while the control group proportion increased slightly (79%, 86% and 87%). Parental weekday TV watching decreased in both groups. In post-study interviews many mothers reported problems associated with wearing the accelerometers. In terms of a future full-scale trial, a sample of between 80 and 340 families would be needed to detect a mean difference of 10-minutes of weekend MVPA. Conclusions: Teamplay is a promising parenting program in an under-researched area. The intervention was acceptable to parents, and all elements of the study protocol were successfully completed. Simple changes to the trial protocol could result in more complete data collection and study engagement

Variability of quasilinear diffusion coefficients for plasmaspheric hiss

In the Outer Radiation Belt, the acceleration and loss of high-energy electrons is largely controlled by wave-particle interactions. Quasilinear diffusion coefficients are an efficient way to capture the small-scale physics of wave-particle interactions due to magnetospheric wave modes such as plasmaspheric hiss. The strength of quasilinear diffusion coefficients as a function of energy and pitch-angle depends on both wave parameters and plasma parameters such as ambient magnetic field strength, plasma number density and composition. For plasmaspheric hiss in the magnetosphere, observations indicate large variations in the wave intensity and wavenormal angle, but less is known about the simultaneous variability of the magnetic field and number density. We use in-situ measurements from the Van Allen Probe mission to demonstrate the variability of selected factors that control the size and shape of pitch-angle diffusion coefficients: wave intensity, magnetic field strength and electron number density. We then compare with the variability of diffusion coefficients calculated individually from co-located and simultaneous groups of measurements. We show that the distribution of the plasmaspheric hiss diffusion coefficients is highly non-Gaussian with large variance, and that the distributions themselves vary strongly across the three phase-space bins studied. In most bins studied, the plasmaspheric hiss diffusion coefficients tend to increase with geomagnetic activity, but our results indicate that new approaches that include natural variability may yield improved parameterizations. We suggest methods like stochastic parameterization of wave-particle interactions could use variability information to improve modelling of the Outer Radiation Belt

Parental modelling, media equipment and screen-viewing among young children : cross-sectional study

Objective: To examine whether parental screenviewing, parental attitudes or access to media equipment were associated with the screen-viewing of 6-year-old to 8-year-old children. Design: Cross-sectional survey. Setting: Online survey. Main outcome: Parental report of the number of hours per weekday that they and, separately, their 6- year-old to 8-year-old child spent watching TV, using a games console, a smart-phone and multiscreen viewing. Parental screen-viewing, parental attitudes and pieces of media equipment were exposures. Results: Over 75% of the parents and 62% of the children spent more than 2 h/weekday watching TV. Over two-thirds of the parents and almost 40% of the children spent more than an hour per day multiscreen viewing. The mean number of pieces of media equipment in the home was 5.9 items, with 1.3 items in the child’s bedroom. Children who had parents who spent more than 2 h/day watching TV were over 7.8 times more likely to exceed the 2 h threshold. Girls and boys who had a parent who spent an hour or more multiscreen viewing were 34 times more likely to also spend more than an hour per day multiscreen viewing. Media equipment in the child’s bedroom was associated with higher TV viewing, computer time and multiscreen viewing. Each increment in the parental agreement that watching TV was relaxing for their child was associated with a 49% increase in the likelihood that the child spent more than 2 h/day watching TV. Conclusions: Children who have parents who engage in high levels of screen-viewing are more likely to engage in high levels of screen-viewing. Access to media equipment, particularly in the child’s bedroom, was associated with higher levels of screen-viewing. Family-based strategies to reduce screen-viewing and limit media equipment access may be important ways to reduce child screen-viewing