Robust nonlinear control of vectored thrust aircraft

NASA Technical Reports Server (NTRS)

Doyle, John C.; Murray, Richard; Morris, John

1993-01-01

An interdisciplinary program in robust control for nonlinear systems with applications to a variety of engineering problems is outlined. Major emphasis will be placed on flight control, with both experimental and analytical studies. This program builds on recent new results in control theory for stability, stabilization, robust stability, robust performance, synthesis, and model reduction in a unified framework using Linear Fractional Transformations (LFT's), Linear Matrix Inequalities (LMI's), and the structured singular value micron. Most of these new advances have been accomplished by the Caltech controls group independently or in collaboration with researchers in other institutions. These recent results offer a new and remarkably unified framework for all aspects of robust control, but what is particularly important for this program is that they also have important implications for system identification and control of nonlinear systems. This combines well with Caltech's expertise in nonlinear control theory, both in geometric methods and methods for systems with constraints and saturations.

A Robust Cooperated Control Method with Reinforcement Learning and Adaptive H∞ Control

NASA Astrophysics Data System (ADS)

Obayashi, Masanao; Uchiyama, Shogo; Kuremoto, Takashi; Kobayashi, Kunikazu

This study proposes a robust cooperated control method combining reinforcement learning with robust control to control the system. A remarkable characteristic of the reinforcement learning is that it doesn't require model formula, however, it doesn't guarantee the stability of the system. On the other hand, robust control system guarantees stability and robustness, however, it requires model formula. We employ both the actor-critic method which is a kind of reinforcement learning with minimal amount of computation to control continuous valued actions and the traditional robust control, that is, H∞ control. The proposed system was compared method with the conventional control method, that is, the actor-critic only used, through the computer simulation of controlling the angle and the position of a crane system, and the simulation result showed the effectiveness of the proposed method.

Feedforward/feedback control synthesis for performance and robustness

NASA Technical Reports Server (NTRS)

Wie, Bong; Liu, Qiang

1990-01-01

Both feedforward and feedback control approaches for uncertain dynamical systems are investigated. The control design objective is to achieve a fast settling time (high performance) and robustness (insensitivity) to plant modeling uncertainty. Preshapong of an ideal, time-optimal control input using a 'tapped-delay' filter is shown to provide a rapid maneuver with robust performance. A robust, non-minimum-phase feedback controller is synthesized with particular emphasis on its proper implementation for a non-zero set-point control problem. The proposed feedforward/feedback control approach is robust for a certain class of uncertain dynamical systems, since the control input command computed for a given desired output does not depend on the plant parameters.

Modern CACSD using the Robust-Control Toolbox

NASA Technical Reports Server (NTRS)

Chiang, Richard Y.; Safonov, Michael G.

1989-01-01

The Robust-Control Toolbox is a collection of 40 M-files which extend the capability of PC/PRO-MATLAB to do modern multivariable robust control system design. Included are robust analysis tools like singular values and structured singular values, robust synthesis tools like continuous/discrete H(exp 2)/H infinity synthesis and Linear Quadratic Gaussian Loop Transfer Recovery methods and a variety of robust model reduction tools such as Hankel approximation, balanced truncation and balanced stochastic truncation, etc. The capabilities of the toolbox are described and illustated with examples to show how easily they can be used in practice. Examples include structured singular value analysis, H infinity loop-shaping and large space structure model reduction.

Surrogate endpoints for overall survival in metastatic melanoma: a meta-analysis of randomised controlled trials

PubMed Central

Flaherty, Keith T; Hennig, Michael; Lee, Sandra J; Ascierto, Paolo A; Dummer, Reinhard; Eggermont, Alexander M M; Hauschild, Axel; Kefford, Richard; Kirkwood, John M; Long, Georgina V; Lorigan, Paul; Mackensen, Andreas; McArthur, Grant; O'Day, Steven; Patel, Poulam M; Robert, Caroline; Schadendorf, Dirk

2015-01-01

Summary Background Recent phase 3 trials have shown an overall survival benefit in metastatic melanoma. We aimed to assess whether progression-free survival (PFS) could be regarded as a reliable surrogate for overall survival through a meta-analysis of randomised trials. Methods We systematically reviewed randomised trials comparing treatment regimens in metastatic melanoma that included dacarbazine as the control arm, and which reported both PFS and overall survival with a standard hazard ratio (HR). We correlated HRs for overall survival and PFS, weighted by sample size or by precision of the HR estimate, assuming fixed and random effects. We did sensitivity analyses according to presence of crossover, trial size, and dacarbazine dose. Findings After screening 1649 reports and meeting abstracts published before Sept 8, 2013, we identified 12 eligible randomised trials that enrolled 4416 patients with metastatic melanoma. Irrespective of weighting strategy, we noted a strong correlation between the treatment effects for PFS and overall survival, which seemed independent of treatment type. Pearson correlation coefficients were 0.71 (95% CI 0.29–0.90) with a random-effects assumption, 0.85 (0.59–0.95) with a fixed-effects assumption, and 0.89 (0.68–0.97) with sample-size weighting. For nine trials without crossover, the correlation coefficient was 0.96 (0.81–0.99), which decreased to 0.93 (0.74–0.98) when two additional trials with less than 50% crossover were included. Inclusion of mature follow-up data after at least 50% crossover (in vemurafenib and dabrafenib phase 3 trials) weakened the PFS to overall survival correlation (0.55, 0.03–0.84). Inclusion of trials with no or little crossover with the random-effects assumption yielded a conservative statement of the PFS to overall survival correlation of 0.85 (0.51–0.96). Interpretation PFS can be regarded as a robust surrogate for overall survival in dacarbazine-controlled randomised trials of

Robust adaptive vibration control of a flexible structure.

PubMed

Khoshnood, A M; Moradi, H M

2014-07-01

Different types of L1 adaptive control systems show that using robust theories with adaptive control approaches has produced high performance controllers. In this study, a model reference adaptive control scheme considering robust theories is used to propose a practical control system for vibration suppression of a flexible launch vehicle (FLV). In this method, control input of the system is shaped from the dynamic model of the vehicle and components of the control input are adaptively constructed by estimating the undesirable vibration frequencies. Robust stability of the adaptive vibration control system is guaranteed by using the L1 small gain theorem. Simulation results of the robust adaptive vibration control strategy confirm that the effects of vibration on the vehicle performance considerably decrease without the loss of the phase margin of the system. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Robust Control Design for Systems With Probabilistic Uncertainty

NASA Technical Reports Server (NTRS)

Crespo, Luis G.; Kenny, Sean P.

2005-01-01

This paper presents a reliability- and robustness-based formulation for robust control synthesis for systems with probabilistic uncertainty. In a reliability-based formulation, the probability of violating design requirements prescribed by inequality constraints is minimized. In a robustness-based formulation, a metric which measures the tendency of a random variable/process to cluster close to a target scalar/function is minimized. A multi-objective optimization procedure, which combines stability and performance requirements in time and frequency domains, is used to search for robustly optimal compensators. Some of the fundamental differences between the proposed strategy and conventional robust control methods are: (i) unnecessary conservatism is eliminated since there is not need for convex supports, (ii) the most likely plants are favored during synthesis allowing for probabilistic robust optimality, (iii) the tradeoff between robust stability and robust performance can be explored numerically, (iv) the uncertainty set is closely related to parameters with clear physical meaning, and (v) compensators with improved robust characteristics for a given control structure can be synthesized.

A multi-centre randomised controlled trial of rehabilitation aimed at improving outdoor mobility for people after stroke: Study protocol for a randomised controlled trial

PubMed Central

2012-01-01

. Discussion This study protocol describes a pragmatic randomised controlled trial that will hopefully provide robust evidence of the benefit of outdoor mobility interventions after stroke for clinicians working in the community. The results will be available towards the end of 2012. Trial registration ISRCTN58683841 PMID:22721452

Subgroup analyses in randomised controlled trials: cohort study on trial protocols and journal publications.

PubMed

Kasenda, Benjamin; Schandelmaier, Stefan; Sun, Xin; von Elm, Erik; You, John; Blümle, Anette; Tomonaga, Yuki; Saccilotto, Ramon; Amstutz, Alain; Bengough, Theresa; Meerpohl, Joerg J; Stegert, Mihaela; Olu, Kelechi K; Tikkinen, Kari A O; Neumann, Ignacio; Carrasco-Labra, Alonso; Faulhaber, Markus; Mulla, Sohail M; Mertz, Dominik; Akl, Elie A; Bassler, Dirk; Busse, Jason W; Ferreira-González, Ignacio; Lamontagne, Francois; Nordmann, Alain; Gloy, Viktoria; Raatz, Heike; Moja, Lorenzo; Rosenthal, Rachel; Ebrahim, Shanil; Vandvik, Per O; Johnston, Bradley C; Walter, Martin A; Burnand, Bernard; Schwenkglenks, Matthias; Hemkens, Lars G; Bucher, Heiner C; Guyatt, Gordon H; Briel, Matthias

2014-07-16

To investigate the planning of subgroup analyses in protocols of randomised controlled trials and the agreement with corresponding full journal publications. Cohort of protocols of randomised controlled trial and subsequent full journal publications. Six research ethics committees in Switzerland, Germany, and Canada. 894 protocols of randomised controlled trial involving patients approved by participating research ethics committees between 2000 and 2003 and 515 subsequent full journal publications. Of 894 protocols of randomised controlled trials, 252 (28.2%) included one or more planned subgroup analyses. Of those, 17 (6.7%) provided a clear hypothesis for at least one subgroup analysis, 10 (4.0%) anticipated the direction of a subgroup effect, and 87 (34.5%) planned a statistical test for interaction. Industry sponsored trials more often planned subgroup analyses compared with investigator sponsored trials (195/551 (35.4%) v 57/343 (16.6%), P<0.001). Of 515 identified journal publications, 246 (47.8%) reported at least one subgroup analysis. In 81 (32.9%) of the 246 publications reporting subgroup analyses, authors stated that subgroup analyses were prespecified, but this was not supported by 28 (34.6%) corresponding protocols. In 86 publications, authors claimed a subgroup effect, but only 36 (41.9%) corresponding protocols reported a planned subgroup analysis. Subgroup analyses are insufficiently described in the protocols of randomised controlled trials submitted to research ethics committees, and investigators rarely specify the anticipated direction of subgroup effects. More than one third of statements in publications of randomised controlled trials about subgroup prespecification had no documentation in the corresponding protocols. Definitive judgments regarding credibility of claimed subgroup effects are not possible without access to protocols and analysis plans of randomised controlled trials. © The DISCO study group 2014.

Synthesis Methods for Robust Passification and Control

NASA Technical Reports Server (NTRS)

Kelkar, Atul G.; Joshi, Suresh M. (Technical Monitor)

2000-01-01

The research effort under this cooperative agreement has been essentially the continuation of the work from previous grants. The ongoing work has primarily focused on developing passivity-based control techniques for Linear Time-Invariant (LTI) systems. During this period, there has been a significant progress made in the area of passivity-based control of LTI systems and some preliminary results have also been obtained for nonlinear systems, as well. The prior work has addressed optimal control design for inherently passive as well as non- passive linear systems. For exploiting the robustness characteristics of passivity-based controllers the passification methodology was developed for LTI systems that are not inherently passive. Various methods of passification were first proposed in and further developed. The robustness of passification was addressed for multi-input multi-output (MIMO) systems for certain classes of uncertainties using frequency-domain methods. For MIMO systems, a state-space approach using Linear Matrix Inequality (LMI)-based formulation was presented, for passification of non-passive LTI systems. An LMI-based robust passification technique was presented for systems with redundant actuators and sensors. The redundancy in actuators and sensors was used effectively for robust passification using the LMI formulation. The passification was designed to be robust to an interval-type uncertainties in system parameters. The passification techniques were used to design a robust controller for Benchmark Active Control Technology wing under parametric uncertainties. The results on passive nonlinear systems, however, are very limited to date. Our recent work in this area was presented, wherein some stability results were obtained for passive nonlinear systems that are affine in control.

A Robust H ∞ Controller for an UAV Flight Control System

PubMed Central

López, J.

2015-01-01

The objective of this paper is the implementation and validation of a robust H ∞ controller for an UAV to track all types of manoeuvres in the presence of noisy environment. A robust inner-outer loop strategy is implemented. To design the H ∞ robust controller in the inner loop, H ∞ control methodology is used. The two controllers that conform the outer loop are designed using the H ∞ Loop Shaping technique. The reference vector used in the control architecture formed by vertical velocity, true airspeed, and heading angle, suggests a nontraditional way to pilot the aircraft. The simulation results show that the proposed control scheme works well despite the presence of noise and uncertainties, so the control system satisfies the requirements. PMID:26221622

A Robust H ∞ Controller for an UAV Flight Control System.

PubMed

López, J; Dormido, R; Dormido, S; Gómez, J P

2015-01-01

The objective of this paper is the implementation and validation of a robust H ∞ controller for an UAV to track all types of manoeuvres in the presence of noisy environment. A robust inner-outer loop strategy is implemented. To design the H ∞ robust controller in the inner loop, H ∞ control methodology is used. The two controllers that conform the outer loop are designed using the H ∞ Loop Shaping technique. The reference vector used in the control architecture formed by vertical velocity, true airspeed, and heading angle, suggests a nontraditional way to pilot the aircraft. The simulation results show that the proposed control scheme works well despite the presence of noise and uncertainties, so the control system satisfies the requirements.

A randomised controlled trial of dietary improvement for adults with major depression (the 'SMILES' trial).

PubMed

Jacka, Felice N; O'Neil, Adrienne; Opie, Rachelle; Itsiopoulos, Catherine; Cotton, Sue; Mohebbi, Mohammedreza; Castle, David; Dash, Sarah; Mihalopoulos, Cathrine; Chatterton, Mary Lou; Brazionis, Laima; Dean, Olivia M; Hodge, Allison M; Berk, Michael

2017-01-30

The possible therapeutic impact of dietary changes on existing mental illness is largely unknown. Using a randomised controlled trial design, we aimed to investigate the efficacy of a dietary improvement program for the treatment of major depressive episodes. 'SMILES' was a 12-week, parallel-group, single blind, randomised controlled trial of an adjunctive dietary intervention in the treatment of moderate to severe depression. The intervention consisted of seven individual nutritional consulting sessions delivered by a clinical dietician. The control condition comprised a social support protocol to the same visit schedule and length. Depression symptomatology was the primary endpoint, assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS) at 12 weeks. Secondary outcomes included remission and change of symptoms, mood and anxiety. Analyses utilised a likelihood-based mixed-effects model repeated measures (MMRM) approach. The robustness of estimates was investigated through sensitivity analyses. We assessed 166 individuals for eligibility, of whom 67 were enrolled (diet intervention, n = 33; control, n = 34). Of these, 55 were utilising some form of therapy: 21 were using psychotherapy and pharmacotherapy combined; 9 were using exclusively psychotherapy; and 25 were using only pharmacotherapy. There were 31 in the diet support group and 25 in the social support control group who had complete data at 12 weeks. The dietary support group demonstrated significantly greater improvement between baseline and 12 weeks on the MADRS than the social support control group, t(60.7) = 4.38, p < 0.001, Cohen's d = -1.16. Remission, defined as a MADRS score <10, was achieved for 32.3% (n = 10) and 8.0% (n = 2) of the intervention and control groups, respectively (χ 2 (1) = 4.84, p = 0.028); number needed to treat (NNT) based on remission scores was 4.1 (95% CI of NNT 2.3-27.8). A sensitivity analysis, testing departures from the

Psychosocial consequences of allocation to lung cancer screening: a randomised controlled trial.

PubMed

Aggestrup, Louise Mosborg; Hestbech, Mie Sara; Siersma, Volkert; Pedersen, Jesper Holst; Brodersen, John

2012-01-01

To examine the psychosocial consequences of being allocated to the control group as compared with the screen group in a randomised lung cancer screening trial. The Danish Lung Cancer Screening Trial, a randomised controlled trial, ran from 2004 to 2010 with the purpose of investigating the benefits and harms of lung cancer screening. The participants in Danish Lung Cancer Screening Trial were randomised to either the control group or the screen group and were asked to complete the questionnaires Consequences Of Screening and Consequences Of Screening in Lung Cancer (COS-LC). The Consequences Of Screening and the COS-LC were used to examine the psychosocial consequences of participating in the study, by comparing the control and the screen groups' responses at the prevalence and at the incidence round. There was no statistically significant difference in socio-demographic characteristics or smoking habits between the two groups. Responses to the COS-LC collected before the incidence round were statistically significantly different on the scales 'anxiety', 'behaviour', 'dejection', 'self-blame', 'focus on airway symptoms' and 'introvert', with the control group reporting higher negative psychosocial consequences. Furthermore, the participants in both the control and the screen groups exhibited a mean increase in negative psychosocial consequences when their responses from the prevalence round were compared with their responses from the first incidence round. Participation in a randomised controlled trial on lung cancer screening has negative psychosocial consequences for the apparently healthy participants-both the participants in the screen group and the control group. This negative impact was greatest for the control group.

Real-time control systems: feedback, scheduling and robustness

NASA Astrophysics Data System (ADS)

Simon, Daniel; Seuret, Alexandre; Sename, Olivier

2017-08-01

The efficient control of real-time distributed systems, where continuous components are governed through digital devices and communication networks, needs a careful examination of the constraints arising from the different involved domains inside co-design approaches. Thanks to the robustness of feedback control, both new control methodologies and slackened real-time scheduling schemes are proposed beyond the frontiers between these traditionally separated fields. A methodology to design robust aperiodic controllers is provided, where the sampling interval is considered as a control variable of the system. Promising experimental results are provided to show the feasibility and robustness of the approach.

Robust tracking control of a magnetically suspended rigid body

NASA Technical Reports Server (NTRS)

Lim, Kyong B.; Cox, David E.

1994-01-01

This study is an application of H-infinity and micro-synthesis for designing robust tracking controllers for the Large Angle Magnetic Suspension Test Facility. The modeling, design, analysis, simulation, and testing of a control law that guarantees tracking performance under external disturbances and model uncertainties is investigated. The type of uncertainties considered and the tracking performance metric used is discussed. This study demonstrates the tradeoff between tracking performance at low frequencies and robustness at high frequencies. Two sets of controllers were designed and tested. The first set emphasized performance over robustness, while the second set traded off performance for robustness. Comparisons of simulation and test results are also included. Current simulation and experimental results indicate that reasonably good robust tracking performance can be attained for this system using multivariable robust control approach.

Facilitating return to work through early specialist health-based interventions (FRESH): protocol for a feasibility randomised controlled trial.

PubMed

Radford, Kathryn A; Phillips, Julie; Jones, Trevor; Gibson, Ali; Sutton, Chris; Watkins, Caroline; Sach, Tracey; Duley, Lelia; Walker, Marion; Drummond, Avril; Hoffman, Karen; O'Connor, Rory; Forshaw, Denise; Shakespeare, David

2015-01-01

Over one million people sustain traumatic brain injury each year in the UK and more than 10 % of these are moderate or severe injuries, resulting in cognitive and psychological problems that affect the ability to work. Returning to work is a primary rehabilitation goal but fewer than half of traumatic brain injury survivors achieve this. Work is a recognised health service outcome, yet UK service provision varies widely and there is little robust evidence to inform rehabilitation practice. A single-centre cohort comparison suggested better work outcomes may be achieved through early occupational therapy targeted at job retention. This study aims to determine whether this intervention can be delivered in three new trauma centres and to conduct a feasibility, randomised controlled trial to determine whether its effects and cost effectiveness can be measured to inform a definitive trial. Mixed methods study, including feasibility randomised controlled trial, embedded qualitative studies and feasibility economic evaluation will recruit 102 people with traumatic brain injury and their nominated carers from three English UK National Health Service (NHS) trauma centres. Participants will be randomised to receive either usual NHS rehabilitation or usual rehabilitation plus early specialist traumatic brain injury vocational rehabilitation delivered by an occupational therapist. The primary objective is to assess the feasibility of conducting a definitive trial; secondary objectives include measurement of protocol integrity (inclusion/exclusion criteria, intervention adherence, reasons for non-adherence) recruitment rate, the proportion of eligible patients recruited, reasons for non-recruitment, spectrum of TBI severity, proportion of and reasons for loss to follow-up, completeness of data collection, gains in face-to-face V s postal data collection and the most appropriate methods of measuring primary outcomes (return to work, retention) to determine the sample size for a

Randomised controlled trial of rhinothermy for treatment of the common cold: a feasibility study

PubMed Central

van de Hei, Susanne; McKinstry, Steven; Bardsley, George; Weatherall, Mark; Beasley, Richard; Fingleton, James

2018-01-01

Objective To determine the feasibility of a randomised controlled trial (RCT) of rhinothermy for the common cold. Design Open label, randomised, controlled feasibility study. Setting Single-centre research institute in New Zealand recruiting participants from the community. Participants 30 adult participants with symptoms of a common cold, presenting within 48 hours of the onset of symptoms. Interventions Participants were randomly assigned 2:1 to receive either 35 L/min of 100% humidified air at 41°C via high flow nasal cannulae, 2 hours per day for up to 5 days (rhinothermy), or vitamin C 250 mg daily for 5 days (control). Primary and secondary outcome measures The primary outcome was the proportion of screened candidates who were randomised. Secondary outcomes included: proportion of randomised participants who completed the study; modified Jackson scores from randomisation to 10 days after initiation of randomised regimen; time until feeling ‘a lot better’ compared with study entry; time until resolution of symptoms or symptom score at 10 days postrandomisation; proportion of organisms identified by PCR analysis of nasal swabs taken at baseline; the patterns of use of the rhinothermy device; estimated adherence of the control group; and rhinothermy device tolerability. Results In all 30/79 (38%, 95% CI 27% to 50%) of potential participants screened for eligibility were randomised. Rhinothermy was well tolerated, and all randomised participants completed the study (100%, 95% CI 88% to 100%). The reduction from baseline in the modified Jackson score was greater with rhinothermy compared with control at days 2, 3, 4, 5 and 6, with the maximum difference at day 4 (−6.4, 95% CI −9.4 to −3.3). The substantial clinical benefit threshold for modified Jackson score was a 5-unit change. Conclusions This study shows that an RCT of rhinothermy compared with low-dose vitamin C in the treatment of the common cold is feasible. Trial registration

Closed-loop and robust control of quantum systems.

PubMed

Chen, Chunlin; Wang, Lin-Cheng; Wang, Yuanlong

2013-01-01

For most practical quantum control systems, it is important and difficult to attain robustness and reliability due to unavoidable uncertainties in the system dynamics or models. Three kinds of typical approaches (e.g., closed-loop learning control, feedback control, and robust control) have been proved to be effective to solve these problems. This work presents a self-contained survey on the closed-loop and robust control of quantum systems, as well as a brief introduction to a selection of basic theories and methods in this research area, to provide interested readers with a general idea for further studies. In the area of closed-loop learning control of quantum systems, we survey and introduce such learning control methods as gradient-based methods, genetic algorithms (GA), and reinforcement learning (RL) methods from a unified point of view of exploring the quantum control landscapes. For the feedback control approach, the paper surveys three control strategies including Lyapunov control, measurement-based control, and coherent-feedback control. Then such topics in the field of quantum robust control as H(∞) control, sliding mode control, quantum risk-sensitive control, and quantum ensemble control are reviewed. The paper concludes with a perspective of future research directions that are likely to attract more attention.

Closed-Loop and Robust Control of Quantum Systems

PubMed Central

Wang, Lin-Cheng

2013-01-01

For most practical quantum control systems, it is important and difficult to attain robustness and reliability due to unavoidable uncertainties in the system dynamics or models. Three kinds of typical approaches (e.g., closed-loop learning control, feedback control, and robust control) have been proved to be effective to solve these problems. This work presents a self-contained survey on the closed-loop and robust control of quantum systems, as well as a brief introduction to a selection of basic theories and methods in this research area, to provide interested readers with a general idea for further studies. In the area of closed-loop learning control of quantum systems, we survey and introduce such learning control methods as gradient-based methods, genetic algorithms (GA), and reinforcement learning (RL) methods from a unified point of view of exploring the quantum control landscapes. For the feedback control approach, the paper surveys three control strategies including Lyapunov control, measurement-based control, and coherent-feedback control. Then such topics in the field of quantum robust control as H ∞ control, sliding mode control, quantum risk-sensitive control, and quantum ensemble control are reviewed. The paper concludes with a perspective of future research directions that are likely to attract more attention. PMID:23997680

Multi-application controls: Robust nonlinear multivariable aerospace controls applications

NASA Technical Reports Server (NTRS)

Enns, Dale F.; Bugajski, Daniel J.; Carter, John; Antoniewicz, Bob

1994-01-01

This viewgraph presentation describes the general methodology used to apply Honywell's Multi-Application Control (MACH) and the specific application to the F-18 High Angle-of-Attack Research Vehicle (HARV) including piloted simulation handling qualities evaluation. The general steps include insertion of modeling data for geometry and mass properties, aerodynamics, propulsion data and assumptions, requirements and specifications, e.g. definition of control variables, handling qualities, stability margins and statements for bandwidth, control power, priorities, position and rate limits. The specific steps include choice of independent variables for least squares fits to aerodynamic and propulsion data, modifications to the management of the controls with regard to integrator windup and actuation limiting and priorities, e.g. pitch priority over roll, and command limiting to prevent departures and/or undesirable inertial coupling or inability to recover to a stable trim condition. The HARV control problem is characterized by significant nonlinearities and multivariable interactions in the low speed, high angle-of-attack, high angular rate flight regime. Systematic approaches to the control of vehicle motions modeled with coupled nonlinear equations of motion have been developed. This paper will discuss the dynamic inversion approach which explicity accounts for nonlinearities in the control design. Multiple control effectors (including aerodynamic control surfaces and thrust vectoring control) and sensors are used to control the motions of the vehicles in several degrees-of-freedom. Several maneuvers will be used to illustrate performance of MACH in the high angle-of-attack flight regime. Analytical methods for assessing the robust performance of the multivariable control system in the presence of math modeling uncertainty, disturbances, and commands have reached a high level of maturity. The structured singular value (mu) frequency response methodology is presented

Identification and robust control of an experimental servo motor.

PubMed

Adam, E J; Guestrin, E D

2002-04-01

In this work, the design of a robust controller for an experimental laboratory-scale position control system based on a dc motor drive as well as the corresponding identification and robust stability analysis are presented. In order to carry out the robust design procedure, first, a classic closed-loop identification technique is applied and then, the parametrization by internal model control is used. The model uncertainty is evaluated under both parametric and global representation. For the latter case, an interesting discussion about the conservativeness of this description is presented by means of a comparison between the uncertainty disk and the critical perturbation radius approaches. Finally, conclusions about the performance of the experimental system with the robust controller are discussed using comparative graphics of the controlled variable and the Nyquist stability margin as a robustness measurement.

Psychosocial consequences of allocation to lung cancer screening: a randomised controlled trial

PubMed Central

Aggestrup, Louise Mosborg; Hestbech, Mie Sara; Siersma, Volkert; Pedersen, Jesper Holst

2012-01-01

Objective To examine the psychosocial consequences of being allocated to the control group as compared with the screen group in a randomised lung cancer screening trial. Method The Danish Lung Cancer Screening Trial, a randomised controlled trial, ran from 2004 to 2010 with the purpose of investigating the benefits and harms of lung cancer screening. The participants in Danish Lung Cancer Screening Trial were randomised to either the control group or the screen group and were asked to complete the questionnaires Consequences Of Screening and Consequences Of Screening in Lung Cancer (COS-LC). The Consequences Of Screening and the COS-LC were used to examine the psychosocial consequences of participating in the study, by comparing the control and the screen groups' responses at the prevalence and at the incidence round. Results There was no statistically significant difference in socio-demographic characteristics or smoking habits between the two groups. Responses to the COS-LC collected before the incidence round were statistically significantly different on the scales ‘anxiety’, ‘behaviour’, ‘dejection’, ‘self-blame’, ‘focus on airway symptoms’ and ‘introvert’, with the control group reporting higher negative psychosocial consequences. Furthermore, the participants in both the control and the screen groups exhibited a mean increase in negative psychosocial consequences when their responses from the prevalence round were compared with their responses from the first incidence round. Conclusions Participation in a randomised controlled trial on lung cancer screening has negative psychosocial consequences for the apparently healthy participants—both the participants in the screen group and the control group. This negative impact was greatest for the control group. PMID:22382119

Evaluation of the effectiveness of music therapy in improving the quality of life of palliative care patients: a randomised controlled pilot and feasibility study.

PubMed

McConnell, Tracey; Graham-Wisener, Lisa; Regan, Joan; McKeown, Miriam; Kirkwood, Jenny; Hughes, Naomi; Clarke, Mike; Leitch, Janet; McGrillen, Kerry; Porter, Sam

2016-01-01

Music therapy is frequently used as a palliative therapy. In consonance with the goals of palliative care, the primary aim of music therapy is to improve people's quality of life by addressing their psychological needs and facilitating communication. To date, primarily because of a paucity of robust research, the evidence for music therapy's effectiveness on patient reported outcomes is positive but weak. This pilot and feasibility study will test procedures, outcomes and validated tools; estimate recruitment and attrition rates; and calculate the sample size required for a phase III randomised trial to evaluate the effectiveness of music therapy in improving the quality of life of palliative care patients. A pilot randomised controlled trial supplemented with qualitative methods. The quantitative data collection will involve recruitment of >52 patients from an inpatient Marie Curie hospice setting over a 12-month period. Eligibility criteria include all patients with an Eastern Cooperative Oncology Group (ECOG) performance status of 03- indicating they are medically fit to engage with music therapy and an Abbreviated Mental Test (AMT) score of ≥7 indicating they are capable of providing meaningful informed consent and accurate responses to outcome measures. Baseline data collection will include the McGill Quality of Life Questionnaire (MQOL); medical and socio-demographic data will be undertaken before randomisation to an intervention or control group. Participants in the intervention arm will be offered two 30-45 min sessions of music therapy per week for three consecutive weeks, in addition to care as usual. Participants in the control arm will receive care as usual. Follow-up measures will be administered in 1, 3 and 5 weeks. Qualitative data collection will involve focus group and individual interviews with HCPs and carers. This study will ensure a firm methodological grounding for the development of a robust phase III randomised trial of music therapy for

Research in robust control for hypersonic aircraft

NASA Technical Reports Server (NTRS)

Calise, A. J.

1993-01-01

The research during the second reporting period has focused on robust control design for hypersonic vehicles. An already existing design for the Hypersonic Winged-Cone Configuration has been enhanced. Uncertainty models for the effects of propulsion system perturbations due to angle of attack variations, structural vibrations, and uncertainty in control effectiveness were developed. Using H(sub infinity) and mu-synthesis techniques, various control designs were performed in order to investigate the impact of these effects on achievable robust performance.

Using the 'Social Marketing Mix Framework' to explore recruitment barriers and facilitators in palliative care randomised controlled trials? A narrative synthesis review.

PubMed

Dunleavy, Lesley; Walshe, Catherine; Oriani, Anna; Preston, Nancy

2018-05-01

Effective recruitment to randomised controlled trials is critically important for a robust, trustworthy evidence base in palliative care. Many trials fail to achieve recruitment targets, but the reasons for this are poorly understood. Understanding barriers and facilitators is a critical step in designing optimal recruitment strategies. To identify, explore and synthesise knowledge about recruitment barriers and facilitators in palliative care trials using the '6 Ps' of the 'Social Marketing Mix Framework'. A systematic review with narrative synthesis. Medline, CINAHL, PsycINFO and Embase databases (from January 1990 to early October 2016) were searched. Papers included the following: interventional and qualitative studies addressing recruitment, palliative care randomised controlled trial papers or reports containing narrative observations about the barriers, facilitators or strategies to increase recruitment. A total of 48 papers met the inclusion criteria. Uninterested participants (Product), burden of illness (Price) and 'identifying eligible participants' were barriers. Careful messaging and the use of scripts/role play (Promotion) were recommended. The need for intensive resources and gatekeeping by professionals were barriers while having research staff on-site and lead clinician support (Working with Partners) was advocated. Most evidence is based on researchers' own reports of experiences of recruiting to trials rather than independent evaluation. The 'Social Marketing Mix Framework' can help guide researchers when planning and implementing their recruitment strategy but suggested strategies need to be tested within embedded clinical trials. The findings of this review are applicable to all palliative care research and not just randomised controlled trials.

Robust control synthesis for uncertain dynamical systems

NASA Technical Reports Server (NTRS)

Byun, Kuk-Whan; Wie, Bong; Sunkel, John

1989-01-01

This paper presents robust control synthesis techniques for uncertain dynamical systems subject to structured parameter perturbation. Both QFT (quantitative feedback theory) and H-infinity control synthesis techniques are investigated. Although most H-infinity-related control techniques are not concerned with the structured parameter perturbation, a new way of incorporating the parameter uncertainty in the robust H-infinity control design is presented. A generic model of uncertain dynamical systems is used to illustrate the design methodologies investigated in this paper. It is shown that, for a certain noncolocated structural control problem, use of both techniques results in nonminimum phase compensation.

Robust on-off pulse control of flexible space vehicles

NASA Technical Reports Server (NTRS)

Wie, Bong; Sinha, Ravi

1993-01-01

The on-off reaction jet control system is often used for attitude and orbital maneuvering of various spacecraft. Future space vehicles such as the orbital transfer vehicles, orbital maneuvering vehicles, and space station will extensively use reaction jets for orbital maneuvering and attitude stabilization. The proposed robust fuel- and time-optimal control algorithm is used for a three-mass spacing model of flexible spacecraft. A fuel-efficient on-off control logic is developed for robust rest-to-rest maneuver of a flexible vehicle with minimum excitation of structural modes. The first part of this report is concerned with the problem of selecting a proper pair of jets for practical trade-offs among the maneuvering time, fuel consumption, structural mode excitation, and performance robustness. A time-optimal control problem subject to parameter robustness constraints is formulated and solved. The second part of this report deals with obtaining parameter insensitive fuel- and time- optimal control inputs by solving a constrained optimization problem subject to robustness constraints. It is shown that sensitivity to modeling errors can be significantly reduced by the proposed, robustified open-loop control approach. The final part of this report deals with sliding mode control design for uncertain flexible structures. The benchmark problem of a flexible structure is used as an example for the feedback sliding mode controller design with bounded control inputs and robustness to parameter variations is investigated.

Robust control of electrostatic torsional micromirrors using adaptive sliding-mode control

NASA Astrophysics Data System (ADS)

Sane, Harshad S.; Yazdi, Navid; Mastrangelo, Carlos H.

2005-01-01

This paper presents high-resolution control of torsional electrostatic micromirrors beyond their inherent pull-in instability using robust sliding-mode control (SMC). The objectives of this paper are two-fold - firstly, to demonstrate the applicability of SMC for MEMS devices; secondly - to present a modified SMC algorithm that yields improved control accuracy. SMC enables compact realization of a robust controller tolerant of device characteristic variations and nonlinearities. Robustness of the control loop is demonstrated through extensive simulations and measurements on MEMS with a wide range in their characteristics. Control of two-axis gimbaled micromirrors beyond their pull-in instability with overall 10-bit pointing accuracy is confirmed experimentally. In addition, this paper presents an analysis of the sources of errors in discrete-time implementation of the control algorithm. To minimize these errors, we present an adaptive version of the SMC algorithm that yields substantial performance improvement without considerably increasing implementation complexity.

Robust blood-glucose control using Mathematica.

PubMed

Kovács, Levente; Paláncz, Béla; Benyó, Balázs; Török, László; Benyó, Zoltán

2006-01-01

A robust control design on frequency domain using Mathematica is presented for regularization of glucose level in type I diabetes persons under intensive care. The method originally proposed under Mathematica by Helton and Merino, --now with an improved disturbance rejection constraint inequality--is employed, using a three-state minimal patient model. The robustness of the resulted high-order linear controller is demonstrated by nonlinear closed loop simulation in state-space, in case of standard meal disturbances and is compared with H infinity design implemented with the mu-toolbox of Matlab. The controller designed with model parameters represented the most favorable plant dynamics from the point of view of control purposes, can operate properly even in case of parameter values of the worst-case scenario.

Robust high-performance control for robotic manipulators

NASA Technical Reports Server (NTRS)

Seraji, H.

1989-01-01

A robust control scheme to accomplish accurate trajectory tracking for an integrated system of manipulator-plus-actuators is proposed. The control scheme comprises a feedforward and a feedback controller. The feedforward controller contains any known part of the manipulator dynamics that can be used for online control. The feedback controller consists of adaptive position and velocity feedback gains and an auxiliary signal which is simply generated by a fixed-gain proportional/integral/derivative controller. The feedback controller is updated by very simple adaptation laws which contain both proportional and integral adaptation terms. By introduction of a simple sigma modification to the adaptation laws, robustness is guaranteed in the presence of unmodeled dynamics and disturbances.

Robust Learning Control Design for Quantum Unitary Transformations.

PubMed

Wu, Chengzhi; Qi, Bo; Chen, Chunlin; Dong, Daoyi

2017-12-01

Robust control design for quantum unitary transformations has been recognized as a fundamental and challenging task in the development of quantum information processing due to unavoidable decoherence or operational errors in the experimental implementation of quantum operations. In this paper, we extend the systematic methodology of sampling-based learning control (SLC) approach with a gradient flow algorithm for the design of robust quantum unitary transformations. The SLC approach first uses a "training" process to find an optimal control strategy robust against certain ranges of uncertainties. Then a number of randomly selected samples are tested and the performance is evaluated according to their average fidelity. The approach is applied to three typical examples of robust quantum transformation problems including robust quantum transformations in a three-level quantum system, in a superconducting quantum circuit, and in a spin chain system. Numerical results demonstrate the effectiveness of the SLC approach and show its potential applications in various implementation of quantum unitary transformations.

Effect of intermittent feedback control on robustness of human-like postural control system

NASA Astrophysics Data System (ADS)

Tanabe, Hiroko; Fujii, Keisuke; Suzuki, Yasuyuki; Kouzaki, Motoki

2016-03-01

Humans have to acquire postural robustness to maintain stability against internal and external perturbations. Human standing has been recently modelled using an intermittent feedback control. However, the causality inside of the closed-loop postural control system associated with the neural control strategy is still unknown. Here, we examined the effect of intermittent feedback control on postural robustness and of changes in active/passive components on joint coordinative structure. We implemented computer simulation of a quadruple inverted pendulum that is mechanically close to human tiptoe standing. We simulated three pairs of joint viscoelasticity and three choices of neural control strategies for each joint: intermittent, continuous, or passive control. We examined postural robustness for each parameter set by analysing the region of active feedback gain. We found intermittent control at the hip joint was necessary for model stabilisation and model parameters affected the robustness of the pendulum. Joint sways of the pendulum model were partially smaller than or similar to those of experimental data. In conclusion, intermittent feedback control was necessary for the stabilisation of the quadruple inverted pendulum. Also, postural robustness of human-like multi-link standing would be achieved by both passive joint viscoelasticity and neural joint control strategies.

Effect of intermittent feedback control on robustness of human-like postural control system.

PubMed

Tanabe, Hiroko; Fujii, Keisuke; Suzuki, Yasuyuki; Kouzaki, Motoki

2016-03-02

Humans have to acquire postural robustness to maintain stability against internal and external perturbations. Human standing has been recently modelled using an intermittent feedback control. However, the causality inside of the closed-loop postural control system associated with the neural control strategy is still unknown. Here, we examined the effect of intermittent feedback control on postural robustness and of changes in active/passive components on joint coordinative structure. We implemented computer simulation of a quadruple inverted pendulum that is mechanically close to human tiptoe standing. We simulated three pairs of joint viscoelasticity and three choices of neural control strategies for each joint: intermittent, continuous, or passive control. We examined postural robustness for each parameter set by analysing the region of active feedback gain. We found intermittent control at the hip joint was necessary for model stabilisation and model parameters affected the robustness of the pendulum. Joint sways of the pendulum model were partially smaller than or similar to those of experimental data. In conclusion, intermittent feedback control was necessary for the stabilisation of the quadruple inverted pendulum. Also, postural robustness of human-like multi-link standing would be achieved by both passive joint viscoelasticity and neural joint control strategies.

Randomised Controlled Trials in Education Research: A Case Study of an Individually Randomised Pragmatic Trial

ERIC Educational Resources Information Center

Torgerson, Carole J.

2009-01-01

The randomised controlled trial (RCT) is an evaluative method used by social scientists in order to establish whether or not an intervention is effective. This contribution discusses the fundamental aspects of good RCT design. These are illustrated through the use of a recently completed RCT which evaluated an information and communication…

Robust Control Design for Uncertain Nonlinear Dynamic Systems

NASA Technical Reports Server (NTRS)

Kenny, Sean P.; Crespo, Luis G.; Andrews, Lindsey; Giesy, Daniel P.

2012-01-01

Robustness to parametric uncertainty is fundamental to successful control system design and as such it has been at the core of many design methods developed over the decades. Despite its prominence, most of the work on robust control design has focused on linear models and uncertainties that are non-probabilistic in nature. Recently, researchers have acknowledged this disparity and have been developing theory to address a broader class of uncertainties. This paper presents an experimental application of robust control design for a hybrid class of probabilistic and non-probabilistic parametric uncertainties. The experimental apparatus is based upon the classic inverted pendulum on a cart. The physical uncertainty is realized by a known additional lumped mass at an unknown location on the pendulum. This unknown location has the effect of substantially altering the nominal frequency and controllability of the nonlinear system, and in the limit has the capability to make the system neutrally stable and uncontrollable. Another uncertainty to be considered is a direct current motor parameter. The control design objective is to design a controller that satisfies stability, tracking error, control power, and transient behavior requirements for the largest range of parametric uncertainties. This paper presents an overview of the theory behind the robust control design methodology and the experimental results.

Effect of intermittent feedback control on robustness of human-like postural control system

PubMed Central

Tanabe, Hiroko; Fujii, Keisuke; Suzuki, Yasuyuki; Kouzaki, Motoki

2016-01-01

Humans have to acquire postural robustness to maintain stability against internal and external perturbations. Human standing has been recently modelled using an intermittent feedback control. However, the causality inside of the closed-loop postural control system associated with the neural control strategy is still unknown. Here, we examined the effect of intermittent feedback control on postural robustness and of changes in active/passive components on joint coordinative structure. We implemented computer simulation of a quadruple inverted pendulum that is mechanically close to human tiptoe standing. We simulated three pairs of joint viscoelasticity and three choices of neural control strategies for each joint: intermittent, continuous, or passive control. We examined postural robustness for each parameter set by analysing the region of active feedback gain. We found intermittent control at the hip joint was necessary for model stabilisation and model parameters affected the robustness of the pendulum. Joint sways of the pendulum model were partially smaller than or similar to those of experimental data. In conclusion, intermittent feedback control was necessary for the stabilisation of the quadruple inverted pendulum. Also, postural robustness of human-like multi-link standing would be achieved by both passive joint viscoelasticity and neural joint control strategies. PMID:26931281

Impact of a web-based tool (WebCONSORT) to improve the reporting of randomised trials: results of a randomised controlled trial.

PubMed

Hopewell, Sally; Boutron, Isabelle; Altman, Douglas G; Barbour, Ginny; Moher, David; Montori, Victor; Schriger, David; Cook, Jonathan; Gerry, Stephen; Omar, Omar; Dutton, Peter; Roberts, Corran; Frangou, Eleni; Clifton, Lei; Chiocchia, Virginia; Rombach, Ines; Wartolowska, Karolina; Ravaud, Philippe

2016-11-28

The CONSORT Statement is an evidence-informed guideline for reporting randomised controlled trials. A number of extensions have been developed that specify additional information to report for more complex trials. The aim of this study was to evaluate the impact of using a simple web-based tool (WebCONSORT, which incorporates a number of different CONSORT extensions) on the completeness of reporting of randomised trials published in biomedical publications. We conducted a parallel group randomised trial. Journals which endorsed the CONSORT Statement (i.e. referred to it in the Instruction to Authors) but do not actively implement it (i.e. require authors to submit a completed CONSORT checklist) were invited to participate. Authors of randomised trials were requested by the editor to use the web-based tool at the manuscript revision stage. Authors registering to use the tool were randomised (centralised computer generated) to WebCONSORT or control. In the WebCONSORT group, they had access to a tool allowing them to combine the different CONSORT extensions relevant to their trial and generate a customised checklist and flow diagram that they must submit to the editor. In the control group, authors had only access to a CONSORT flow diagram generator. Authors, journal editors, and outcome assessors were blinded to the allocation. The primary outcome was the proportion of CONSORT items (main and extensions) reported in each article post revision. A total of 46 journals actively recruited authors into the trial (25 March 2013 to 22 September 2015); 324 author manuscripts were randomised (WebCONSORT n = 166; control n = 158), of which 197 were reports of randomised trials (n = 94; n = 103). Over a third (39%; n = 127) of registered manuscripts were excluded from the analysis, mainly because the reported study was not a randomised trial. Of those included in the analysis, the most common CONSORT extensions selected were non-pharmacologic (n = 43; n�

H∞ robust fault-tolerant controller design for an autonomous underwater vehicle's navigation control system

NASA Astrophysics Data System (ADS)

Cheng, Xiang-Qin; Qu, Jing-Yuan; Yan, Zhe-Ping; Bian, Xin-Qian

2010-03-01

In order to improve the security and reliability for autonomous underwater vehicle (AUV) navigation, an H∞ robust fault-tolerant controller was designed after analyzing variations in state-feedback gain. Operating conditions and the design method were then analyzed so that the control problem could be expressed as a mathematical optimization problem. This permitted the use of linear matrix inequalities (LMI) to solve for the H∞ controller for the system. When considering different actuator failures, these conditions were then also mathematically expressed, allowing the H∞ robust controller to solve for these events and thus be fault-tolerant. Finally, simulation results showed that the H∞ robust fault-tolerant controller could provide precise AUV navigation control with strong robustness.

A systematic review of training programmes for recruiters to randomised controlled trials.

PubMed

Townsend, Daisy; Mills, Nicola; Savović, Jelena; Donovan, Jenny L

2015-09-28

Recruitment to randomised controlled trials (RCTs) is often difficult. Clinician related factors have been implicated as important reasons for low rates of recruitment. Clinicians (doctors and other health professionals) can experience discomfort with some underlying principles of RCTs and experience difficulties in conveying them positively to potential trial participants. Recruiter training has been suggested to address identified problems but a synthesis of this research is lacking. The aim of our study was to systematically review the available evidence on training interventions for recruiters to randomised trials. Studies that evaluated training programmes for trial recruiters were included. Those that provided only general communication training not linked to RCT recruitment were excluded. Data extraction and quality assessment were completed by two reviewers independently, with a third author where necessary. Seventeen studies of 9615 potentially eligible titles and abstracts were included in the review: three randomised controlled studies, two non-randomised controlled studies, nine uncontrolled pre-test/post-test studies, two qualitative studies, and a post-training questionnaire survey. Most studies were of moderate or weak quality. Training programmes were mostly set within cancer trials, and usually consisted of workshops with a mix of health professionals over one or two consecutive days covering generic and trial specific issues. Recruiter training programmes were well received and some increased recruiters' self-confidence in communicating key RCT concepts to patients. There was, however, little evidence that this training increased actual recruitment rates or patient understanding, satisfaction, or levels of informed consent. There is a need to develop recruiter training programmes that can lead to improved recruitment and informed consent in randomised trials.

REFINE (Reducing Falls in In-patient Elderly)--a randomised controlled trial.

PubMed

Vass, Catherine D; Sahota, Opinder; Drummond, Avril; Kendrick, Denise; Gladman, John; Sach, Tracey; Avis, Mark; Grainge, Matthew

2009-09-10

Falls in hospitals are common, resulting in injury and anxiety to patients, and large costs to NHS organisations. More than half of all in-patient falls in elderly people in acute care settings occur at the bedside, during transfers or whilst getting up to go to the toilet. In the majority of cases these falls are unwitnessed. There is insufficient evidence underpinning the effectiveness of interventions to guide clinical staff regarding the reduction of falls in the elderly inpatient. New patient monitoring technologies have the potential to offer advances in falls prevention. Bedside sensor equipment can alert staff, not in the immediate vicinity, to a potential problem and avert a fall. However no studies utilizing this assistive technology have demonstrated a significant reduction in falls rates in a randomised controlled trial setting. The research design is an individual patient randomised controlled trial of bedside chair and bed pressure sensors, incorporating a radio-paging alerting mode to alert staff to patients rising from their bed or chair, across five acute elderly care wards in Nottingham University Hospitals NHS Trust. Participants will be randomised to bedside chair and bed sensors or to usual care (without the use of sensors). The primary outcome is the number of bedside in-patient falls. The REFINE study is the first randomised controlled trial of bedside pressure sensors in elderly inpatients in an acute NHS Trust. We will assess whether falls can be successfully and cost effectively reduced using this technology, and report on its acceptability to both patients and staff.

Robust Control of Uncertain Systems via Dissipative LQG-Type Controllers

NASA Technical Reports Server (NTRS)

Joshi, Suresh M.

2000-01-01

Optimal controller design is addressed for a class of linear, time-invariant systems which are dissipative with respect to a quadratic power function. The system matrices are assumed to be affine functions of uncertain parameters confined to a convex polytopic region in the parameter space. For such systems, a method is developed for designing a controller which is dissipative with respect to a given power function, and is simultaneously optimal in the linear-quadratic-Gaussian (LQG) sense. The resulting controller provides robust stability as well as optimal performance. Three important special cases, namely, passive, norm-bounded, and sector-bounded controllers, which are also LQG-optimal, are presented. The results give new methods for robust controller design in the presence of parametric uncertainties.

The effectiveness of robust RMCD control chart as outliers’ detector

NASA Astrophysics Data System (ADS)

Darmanto; Astutik, Suci

2017-12-01

A well-known control chart to monitor a multivariate process is Hotelling’s T 2 which its parameters are estimated classically, very sensitive and also marred by masking and swamping of outliers data effect. To overcome these situation, robust estimators are strongly recommended. One of robust estimators is re-weighted minimum covariance determinant (RMCD) which has robust characteristics as same as MCD. In this paper, the effectiveness term is accuracy of the RMCD control chart in detecting outliers as real outliers. In other word, how effectively this control chart can identify and remove masking and swamping effects of outliers. We assessed the effectiveness the robust control chart based on simulation by considering different scenarios: n sample sizes, proportion of outliers, number of p quality characteristics. We found that in some scenarios, this RMCD robust control chart works effectively.

Lay public's understanding of equipoise and randomisation in randomised controlled trials.

PubMed

Robinson, E J; Kerr, C E P; Stevens, A J; Lilford, R J; Braunholtz, D A; Edwards, S J; Beck, S R; Rowley, M G

2005-03-01

To research the lay public's understanding of equipoise and randomisation in randomised controlled trials (RCTs) and to look at why information on this may not be not taken in or remembered, as well as the effects of providing information designed to overcome barriers. Investigations were informed by an update of systematic review on patients' understanding of consent information in clinical trials, and by relevant theory and evidence from experimental psychology. Nine investigations were conducted with nine participants. Access (return to education), leisure and vocational courses at Further Education Colleges in the Midlands, UK. Healthy adults with a wide range of educational backgrounds and ages. Participants read hypothetical scenarios and wrote brief answers to subsequent questions. Sub-samples of participants were interviewed individually to elaborate on their written answers. Participants' background assumptions concerning equipoise and randomisation were examined and ways of helping participants recognise the scientific benefits of randomisation were explored. Judgments on allocation methods; treatment preferences; the acceptability of random allocation; whether or not individual doctors could be completely unsure about the best treatment; whether or not doctors should reveal treatment preferences under conditions of collective equipoise; and how sure experts would be about the best treatment following random allocation vs doctor/patient choice. Assessments of understanding hypothetical trial information. Recent literature continues to report trial participants' failure to understand or remember information about randomisation and equipoise, despite the provision of clear and readable trial information leaflets. In current best practice, written trial information describes what will happen without offering accessible explanations. As a consequence, patients may create their own incorrect interpretations and consent or refusal may be inadequately informed

Panaceas, uncertainty, and the robust control framework in sustainability science

PubMed Central

Anderies, John M.; Rodriguez, Armando A.; Janssen, Marco A.; Cifdaloz, Oguzhan

2007-01-01

A critical challenge faced by sustainability science is to develop strategies to cope with highly uncertain social and ecological dynamics. This article explores the use of the robust control framework toward this end. After briefly outlining the robust control framework, we apply it to the traditional Gordon–Schaefer fishery model to explore fundamental performance–robustness and robustness–vulnerability trade-offs in natural resource management. We find that the classic optimal control policy can be very sensitive to parametric uncertainty. By exploring a large class of alternative strategies, we show that there are no panaceas: even mild robustness properties are difficult to achieve, and increasing robustness to some parameters (e.g., biological parameters) results in decreased robustness with respect to others (e.g., economic parameters). On the basis of this example, we extract some broader themes for better management of resources under uncertainty and for sustainability science in general. Specifically, we focus attention on the importance of a continual learning process and the use of robust control to inform this process. PMID:17881574

Research on Robust Control Strategies for VSC-HVDC

NASA Astrophysics Data System (ADS)

Zhu, Kaicheng; Bao, Hai

2018-01-01

In the control system of VSC-HVDC, the phase locked loop provides phase signals to voltage vector control and trigger pulses to generate the required reference phase. The PLL is a typical second-order system. When the system is in unstable state, it will oscillate, make the trigger angle shift, produce harmonic, and make active power and reactive power coupled. Thus, considering the external disturbances introduced by the PLL in VSC-HVDC control system, the parameter perturbations of the controller and the model uncertainties, a H∞ robust controller of mixed sensitivity optimization problem is designed by using the Hinf function provided by the robust control toolbox. Then, compare it with the proportional integral controller through the MATLAB simulation experiment. By contrast, when the H∞ robust controller is added, active and reactive power of the converter station can track the change of reference values more accurately and quickly, and reduce overshoot. When the step change of active and reactive power occurs, mutual influence is reduced and better independent regulation is achieved.

Robust output tracking control of a laboratory helicopter for automatic landing

NASA Astrophysics Data System (ADS)

Liu, Hao; Lu, Geng; Zhong, Yisheng

2014-11-01

In this paper, robust output tracking control problem of a laboratory helicopter for automatic landing in high seas is investigated. The motion of the helicopter is required to synchronise with that of an oscillating platform, e.g. the deck of a vessel subject to wave-induced motions. A robust linear time-invariant output feedback controller consisting of a nominal controller and a robust compensator is designed. The robust compensator is introduced to restrain the influences of parametric uncertainties, nonlinearities and external disturbances. It is shown that robust stability and robust tracking property can be achieved simultaneously. Experimental results on the laboratory helicopter for automatic landing demonstrate the effectiveness of the designed control approach.

Diamorphine for pain relief in labour : a randomised controlled trial comparing intramuscular injection and patient-controlled analgesia.

PubMed

McInnes, Rhona J; Hillan, Edith; Clark, Diana; Gilmour, Harper

2004-10-01

To compare the efficacy of diamorphine administered by a patient-controlled pump (patient-controlled analgesia) with intramuscular administration for pain relief in labour. Randomised controlled trial. The South Glasgow University Hospitals NHS Trust. Primigravidae and multigravidae in labour at term (37-42 weeks). Women were randomised in labour to the study (patient-controlled analgesia) or control group (intramuscular). Randomisation was achieved through a random permuted block design stratified by parity. Study group women were given a loading dose of 1.2 mg diamorphine intravenously and then attached to the pump. Control group women received intramuscular diamorphine as per hospital protocol. Participants were also given 3 mg of buccal Stemetil. Data were collected throughout labour and at six postnatal weeks. Analgesia requirements during labour and women's satisfaction with the method of pain relief. Women in the study group (patient-controlled analgesia) used significantly less diamorphine than women in the control group (intramuscular) but were significantly more likely to state that they were very dissatisfied with their use of diamorphine and were significantly more likely to opt out of the trial before the birth of the baby. The majority of women in both groups used other analgesia concurrent with diamorphine such as Entonox, aromatherapy or TENS. Patient-controlled analgesia administration of diamorphine for the relief of pain in labour offers no significant advantages over intramuscular administration. The results also suggest that diamorphine is a poor analgesic for labour pain irrespective of the mode of administration.

Generalized internal model robust control for active front steering intervention

NASA Astrophysics Data System (ADS)

Wu, Jian; Zhao, Youqun; Ji, Xuewu; Liu, Yahui; Zhang, Lipeng

2015-03-01

Because of the tire nonlinearity and vehicle's parameters' uncertainties, robust control methods based on the worst cases, such as H ∞, µ synthesis, have been widely used in active front steering control, however, in order to guarantee the stability of active front steering system (AFS) controller, the robust control is at the cost of performance so that the robust controller is a little conservative and has low performance for AFS control. In this paper, a generalized internal model robust control (GIMC) that can overcome the contradiction between performance and stability is used in the AFS control. In GIMC, the Youla parameterization is used in an improved way. And GIMC controller includes two sections: a high performance controller designed for the nominal vehicle model and a robust controller compensating the vehicle parameters' uncertainties and some external disturbances. Simulations of double lane change (DLC) maneuver and that of braking on split- µ road are conducted to compare the performance and stability of the GIMC control, the nominal performance PID controller and the H ∞ controller. Simulation results show that the high nominal performance PID controller will be unstable under some extreme situations because of large vehicle's parameters variations, H ∞ controller is conservative so that the performance is a little low, and only the GIMC controller overcomes the contradiction between performance and robustness, which can both ensure the stability of the AFS controller and guarantee the high performance of the AFS controller. Therefore, the GIMC method proposed for AFS can overcome some disadvantages of control methods used by current AFS system, that is, can solve the instability of PID or LQP control methods and the low performance of the standard H ∞ controller.

A new robust adaptive controller for vibration control of active engine mount subjected to large uncertainties

NASA Astrophysics Data System (ADS)

Fakhari, Vahid; Choi, Seung-Bok; Cho, Chang-Hyun

2015-04-01

This work presents a new robust model reference adaptive control (MRAC) for vibration control caused from vehicle engine using an electromagnetic type of active engine mount. Vibration isolation performances of the active mount associated with the robust controller are evaluated in the presence of large uncertainties. As a first step, an active mount with linear solenoid actuator is prepared and its dynamic model is identified via experimental test. Subsequently, a new robust MRAC based on the gradient method with σ-modification is designed by selecting a proper reference model. In designing the robust adaptive control, structured (parametric) uncertainties in the stiffness of the passive part of the mount and in damping ratio of the active part of the mount are considered to investigate the robustness of the proposed controller. Experimental and simulation results are presented to evaluate performance focusing on the robustness behavior of the controller in the face of large uncertainties. The obtained results show that the proposed controller can sufficiently provide the robust vibration control performance even in the presence of large uncertainties showing an effective vibration isolation.

Design and implementation of robust controllers for a gait trainer.

PubMed

Wang, F C; Yu, C H; Chou, T Y

2009-08-01

This paper applies robust algorithms to control an active gait trainer for children with walking disabilities. Compared with traditional rehabilitation procedures, in which two or three trainers are required to assist the patient, a motor-driven mechanism was constructed to improve the efficiency of the procedures. First, a six-bar mechanism was designed and constructed to mimic the trajectory of children's ankles in walking. Second, system identification techniques were applied to obtain system transfer functions at different operating points by experiments. Third, robust control algorithms were used to design Hinfinity robust controllers for the system. Finally, the designed controllers were implemented to verify experimentally the system performance. From the results, the proposed robust control strategies are shown to be effective.

Robust hopping based on virtual pendulum posture control.

PubMed

Sharbafi, Maziar A; Maufroy, Christophe; Ahmadabadi, Majid Nili; Yazdanpanah, Mohammad J; Seyfarth, Andre

2013-09-01

A new control approach to achieve robust hopping against perturbations in the sagittal plane is presented in this paper. In perturbed hopping, vertical body alignment has a significant role for stability. Our approach is based on the virtual pendulum concept, recently proposed, based on experimental findings in human and animal locomotion. In this concept, the ground reaction forces are pointed to a virtual support point, named virtual pivot point (VPP), during motion. This concept is employed in designing the controller to balance the trunk during the stance phase. New strategies for leg angle and length adjustment besides the virtual pendulum posture control are proposed as a unified controller. This method is investigated by applying it on an extension of the spring loaded inverted pendulum (SLIP) model. Trunk, leg mass and damping are added to the SLIP model in order to make the model more realistic. The stability is analyzed by Poincaré map analysis. With fixed VPP position, stability, disturbance rejection and moderate robustness are achieved, but with a low convergence speed. To improve the performance and attain higher robustness, an event-based control of the VPP position is introduced, using feedback of the system states at apexes. Discrete linear quartic regulator is used to design the feedback controller. Considerable enhancements with respect to stability, convergence speed and robustness against perturbations and parameter changes are achieved.

Rehabilitation of memory following brain injury (ReMemBrIn): study protocol for a randomised controlled trial.

PubMed

das Nair, Roshan; Lincoln, Nadina B; Ftizsimmons, Deborah; Brain, Nicola; Montgomery, Alan; Bradshaw, Lucy; Drummond, Avril; Sackley, Catherine; Newby, Gavin; Thornton, Jim; Stapleton, Sandip; Pink, Anthony

2015-01-06

Impairments of memory are commonly reported by people with traumatic brain injuries (TBI). Such deficits are persistent, debilitating, and can severely impact quality of life. Currently, many do not routinely receive follow-up appointments for residual memory problems following discharge. This is a multi-centre, randomised controlled trial investigating the clinical and cost-effectiveness of a group-based memory rehabilitation programme. Three hundred and twelve people with a traumatic brain injury will be randomised from four centres. Participants will be eligible if they had a traumatic brain injury more than 3 months prior to recruitment, have memory problems, are 18 to 69 years of age, are able to travel to one of our centres and attend group sessions, and are able to give informed consent. Participants will be randomised in clusters of 4 to 6 to the group rehabilitation intervention or to usual care. Intervention groups will receive 10 weekly sessions of a manualised memory rehabilitation programme, which has been developed in previous pilot studies. The intervention will include restitution strategies to retrain impaired memory functions and compensation strategies to enable participants to cope with their memory problems. All participants will receive a follow-up postal questionnaire and an assessment by a research assistant at 6 and 12 months post-randomisation. The primary outcome is the Everyday Memory Questionnaire at 6 months. Secondary outcomes include the Rivermead Behavioural Memory Test-3, General Health Questionnaire-30, health related quality of life, cost-effectiveness analysis determined by the EQ-5D and a service use questionnaire, individual goal attainment, European Brain Injury Questionnaire (patient and relative versions), and the Everyday Memory Questionnaire-relative version. The primary analysis will be based on intention to treat. A mixed-model regression analysis of the Everyday Memory Questionnaire at 6 months will be used to estimate

Randomised controlled trial of biofeedback training in persistent encopresis with anismus.

PubMed

Nolan, T; Catto-Smith, T; Coffey, C; Wells, J

1998-08-01

Paradoxical external anal sphincter contraction during attempted defecation (anismus) is thought to be an important contributor to chronic faecal retention and encopresis in children. Biofeedback training can be used to teach children to abolish this abnormal contraction. A randomised controlled trial in medical treatment resistant and/or treatment dependent children with anismus using surface electromyographic (EMG) biofeedback training to determine whether such training produces sustained faecal continence. Up to four sessions of biofeedback training were conducted at weekly intervals for each patient. Anorectal manometry was performed before randomisation and six months later. Parents of patients completed the "child behaviour checklist" (CBCL) before randomisation and at follow up. Sixty eight children underwent anorectal manometry and EMG. Of these, 29 had anismus (ages 4-14 years) and were randomised to either EMG biofeedback training and conventional medical treatment (BFT) (n = 14) or to conventional medical treatment alone (n = 15). All but one child were able to learn relaxation of the external anal sphincter on attempted defecation. At six months' follow up, laxative free remission had been sustained in two of 14 patients in the BFT group and in two of 15 controls (95% confidence interval (CI) on difference, -24% to 26%). Remission or improvement occurred in four of 14 patients in the BFT group and six of 15 controls (95% CI on difference, -46% to 23%). Of subjects available for repeat anorectal manometry and EMG at six months, six of 13 in the BFT group still demonstrated anismus v 11 of 13 controls (95% CI on difference, -75% to -1%). Of the four patients in full remission at six months, only one (in the BFT group) did not exhibit anismus. Rectal hyposensitivity was not associated with remission or improvement in either of the groups. Mean CBCL total behaviour problem scores were not significantly different between the BFT and control groups, but there

Randomised controlled trial of biofeedback training in persistent encopresis with anismus

PubMed Central

Nolan, T.; Catto-Smith, T.; Coffey, C.; Wells, J.

1998-01-01

BACKGROUND—Paradoxical external anal sphincter contraction during attempted defecation (anismus) is thought to be an important contributor to chronic faecal retention and encopresis in children. Biofeedback training can be used to teach children to abolish this abnormal contraction.
METHODS—A randomised controlled trial in medical treatment resistant and/or treatment dependent children with anismus using surface electromyographic (EMG) biofeedback training to determine whether such training produces sustained faecal continence. Up to four sessions of biofeedback training were conducted at weekly intervals for each patient. Anorectal manometry was performed before randomisation and six months later. Parents of patients completed the "child behaviour checklist" (CBCL) before randomisation and at follow up.
RESULTS—Sixty eight children underwent anorectal manometry and EMG. Of these, 29 had anismus (ages 4-14 years) and were randomised to either EMG biofeedback training and conventional medical treatment (BFT) (n = 14) or to conventional medical treatment alone (n = 15). All but one child were able to learn relaxation of the external anal sphincter on attempted defecation. At six months' follow up, laxative free remission had been sustained in two of 14 patients in the BFT group and in two of 15 controls (95% confidence interval (CI) on difference, −24% to 26%). Remission or improvement occurred in four of 14 patients in the BFT group and six of 15 controls (95% CI on difference, −46% to 23%). Of subjects available for repeat anorectal manometry and EMG at six months, six of 13 in the BFT group still demonstrated anismus v 11 of 13 controls (95% CI on difference, −75% to −1%). Of the four patients in full remission at six months, only one (in the BFT group) did not exhibit anismus. Rectal hyposensitivity was not associated with remission or improvement in either of the groups. Mean CBCL total behaviour problem scores were not significantly different

A novel robust speed controller scheme for PMBLDC motor.

PubMed

Thirusakthimurugan, P; Dananjayan, P

2007-10-01

The design of speed and position controllers for permanent magnet brushless DC motor (PMBLDC) drive remains as an open problem in the field of motor drives. A precise speed control of PMBLDC motor is complex due to nonlinear coupling between winding currents and rotor speed. In addition, the nonlinearity present in the developed torque due to magnetic saturation of the rotor further complicates this issue. This paper presents a novel control scheme to the conventional PMBLDC motor drive, which aims at improving the robustness by complete decoupling of the design besides minimizing the mutual influence among the speed and current control loops. The interesting feature of this robust control scheme is its suitability for both static and dynamic aspects. The effectiveness of the proposed robust speed control scheme is verified through simulations.

Optimal Robust Motion Controller Design Using Multiobjective Genetic Algorithm

PubMed Central

Svečko, Rajko

2014-01-01

This paper describes the use of a multiobjective genetic algorithm for robust motion controller design. Motion controller structure is based on a disturbance observer in an RIC framework. The RIC approach is presented in the form with internal and external feedback loops, in which an internal disturbance rejection controller and an external performance controller must be synthesised. This paper involves novel objectives for robustness and performance assessments for such an approach. Objective functions for the robustness property of RIC are based on simple even polynomials with nonnegativity conditions. Regional pole placement method is presented with the aims of controllers' structures simplification and their additional arbitrary selection. Regional pole placement involves arbitrary selection of central polynomials for both loops, with additional admissible region of the optimized pole location. Polynomial deviation between selected and optimized polynomials is measured with derived performance objective functions. A multiobjective function is composed of different unrelated criteria such as robust stability, controllers' stability, and time-performance indexes of closed loops. The design of controllers and multiobjective optimization procedure involve a set of the objectives, which are optimized simultaneously with a genetic algorithm—differential evolution. PMID:24987749

Robust control of burst suppression for medical coma

NASA Astrophysics Data System (ADS)

Westover, M. Brandon; Kim, Seong-Eun; Ching, ShiNung; Purdon, Patrick L.; Brown, Emery N.

2015-08-01

Objective. Medical coma is an anesthetic-induced state of brain inactivation, manifest in the electroencephalogram by burst suppression. Feedback control can be used to regulate burst suppression, however, previous designs have not been robust. Robust control design is critical under real-world operating conditions, subject to substantial pharmacokinetic and pharmacodynamic parameter uncertainty and unpredictable external disturbances. We sought to develop a robust closed-loop anesthesia delivery (CLAD) system to control medical coma. Approach. We developed a robust CLAD system to control the burst suppression probability (BSP). We developed a novel BSP tracking algorithm based on realistic models of propofol pharmacokinetics and pharmacodynamics. We also developed a practical method for estimating patient-specific pharmacodynamics parameters. Finally, we synthesized a robust proportional integral controller. Using a factorial design spanning patient age, mass, height, and gender, we tested whether the system performed within clinically acceptable limits. Throughout all experiments we subjected the system to disturbances, simulating treatment of refractory status epilepticus in a real-world intensive care unit environment. Main results. In 5400 simulations, CLAD behavior remained within specifications. Transient behavior after a step in target BSP from 0.2 to 0.8 exhibited a rise time (the median (min, max)) of 1.4 [1.1, 1.9] min; settling time, 7.8 [4.2, 9.0] min; and percent overshoot of 9.6 [2.3, 10.8]%. Under steady state conditions the CLAD system exhibited a median error of 0.1 [-0.5, 0.9]%; inaccuracy of 1.8 [0.9, 3.4]%; oscillation index of 1.8 [0.9, 3.4]%; and maximum instantaneous propofol dose of 4.3 [2.1, 10.5] mg kg-1. The maximum hourly propofol dose was 4.3 [2.1, 10.3] mg kg-1 h-1. Performance fell within clinically acceptable limits for all measures. Significance. A CLAD system designed using robust control theory achieves clinically acceptable

Robust control of burst suppression for medical coma

PubMed Central

Westover, M Brandon; Kim, Seong-Eun; Ching, ShiNung; Purdon, Patrick L; Brown, Emery N

2015-01-01

Objective Medical coma is an anesthetic-induced state of brain inactivation, manifest in the electroencephalogram by burst suppression. Feedback control can be used to regulate burst suppression, however, previous designs have not been robust. Robust control design is critical under real-world operating conditions, subject to substantial pharmacokinetic and pharmacodynamic parameter uncertainty and unpredictable external disturbances. We sought to develop a robust closed-loop anesthesia delivery (CLAD) system to control medical coma. Approach We developed a robust CLAD system to control the burst suppression probability (BSP). We developed a novel BSP tracking algorithm based on realistic models of propofol pharmacokinetics and pharmacodynamics. We also developed a practical method for estimating patient-specific pharmacodynamics parameters. Finally, we synthesized a robust proportional integral controller. Using a factorial design spanning patient age, mass, height, and gender, we tested whether the system performed within clinically acceptable limits. Throughout all experiments we subjected the system to disturbances, simulating treatment of refractory status epilepticus in a real-world intensive care unit environment. Main results In 5400 simulations, CLAD behavior remained within specifications. Transient behavior after a step in target BSP from 0.2 to 0.8 exhibited a rise time (the median (min, max)) of 1.4 [1.1, 1.9] min; settling time, 7.8 [4.2, 9.0] min; and percent overshoot of 9.6 [2.3, 10.8]%. Under steady state conditions the CLAD system exhibited a median error of 0.1 [−0.5, 0.9]%; inaccuracy of 1.8 [0.9, 3.4]%; oscillation index of 1.8 [0.9, 3.4]%; and maximum instantaneous propofol dose of 4.3 [2.1, 10.5] mg kg−1. The maximum hourly propofol dose was 4.3 [2.1, 10.3] mg kg−1 h−1. Performance fell within clinically acceptable limits for all measures. Significance A CLAD system designed using robust control theory achieves clinically acceptable

Outcomes in a Randomised Controlled Trial of Mathematics Tutoring

ERIC Educational Resources Information Center

Topping, K. J.; Miller, D.; Murray, P.; Henderson, S.; Fortuna, C.; Conlin, N.

2011-01-01

Background: Large-scale randomised controlled trials (RCT) are relatively rare in education. The present study was an attempt to scale up previous small peer tutoring projects, while investing only modestly in continuing professional development for teachers. Purpose: A two-year RCT of peer tutoring in mathematics was undertaken in one local…

Treatment of missing data in follow-up studies of randomised controlled trials: A systematic review of the literature.

PubMed

Sullivan, Thomas R; Yelland, Lisa N; Lee, Katherine J; Ryan, Philip; Salter, Amy B

2017-08-01

After completion of a randomised controlled trial, an extended follow-up period may be initiated to learn about longer term impacts of the intervention. Since extended follow-up studies often involve additional eligibility restrictions and consent processes for participation, and a longer duration of follow-up entails a greater risk of participant attrition, missing data can be a considerable threat in this setting. As a potential source of bias, it is critical that missing data are appropriately handled in the statistical analysis, yet little is known about the treatment of missing data in extended follow-up studies. The aims of this review were to summarise the extent of missing data in extended follow-up studies and the use of statistical approaches to address this potentially serious problem. We performed a systematic literature search in PubMed to identify extended follow-up studies published from January to June 2015. Studies were eligible for inclusion if the original randomised controlled trial results were also published and if the main objective of extended follow-up was to compare the original randomised groups. We recorded information on the extent of missing data and the approach used to treat missing data in the statistical analysis of the primary outcome of the extended follow-up study. Of the 81 studies included in the review, 36 (44%) reported additional eligibility restrictions and 24 (30%) consent processes for entry into extended follow-up. Data were collected at a median of 7 years after randomisation. Excluding 28 studies with a time to event primary outcome, 51/53 studies (96%) reported missing data on the primary outcome. The median percentage of randomised participants with complete data on the primary outcome was just 66% in these studies. The most common statistical approach to address missing data was complete case analysis (51% of studies), while likelihood-based analyses were also well represented (25%). Sensitivity analyses around

Use of qualitative methods alongside randomised controlled trials of complex healthcare interventions: methodological study

PubMed Central

Glenton, Claire; Oxman, Andrew D

2009-01-01

Objective To examine the use of qualitative approaches alongside randomised trials of complex healthcare interventions. Design Review of randomised controlled trials of interventions to change professional practice or the organisation of care. Data sources Systematic sample of 100 trials published in English from the register of the Cochrane Effective Practice and Organisation of Care Review Group. Methods Published and unpublished qualitative studies linked to the randomised controlled trials were identified through database searches and contact with authors. Data were extracted from each study by two reviewers using a standard form. We extracted data describing the randomised controlled trials and qualitative studies, the quality of these studies, and how, if at all, the qualitative and quantitative findings were combined. A narrative synthesis of the findings was done. Results 30 of the 100 trials had associated qualitative work and 19 of these were published studies. 14 qualitative studies were done before the trial, nine during the trial, and four after the trial. 13 studies reported an explicit theoretical basis and 11 specified their methodological approach. Approaches to sampling and data analysis were poorly described. For most cases (n=20) we found no indication of integration of qualitative and quantitative findings at the level of either analysis or interpretation. The quality of the qualitative studies was highly variable. Conclusions Qualitative studies alongside randomised controlled trials remain uncommon, even where relatively complex interventions are being evaluated. Most of the qualitative studies were carried out before or during the trials with few studies used to explain trial results. The findings of the qualitative studies seemed to be poorly integrated with those of the trials and often had major methodological shortcomings. PMID:19744976

Association between bibliometric parameters, reporting and methodological quality of randomised controlled trials in vascular and endovascular surgery.

PubMed

Hajibandeh, Shahab; Hajibandeh, Shahin; Antoniou, George A; Green, Patrick A; Maden, Michelle; Torella, Francesco

2017-04-01

Purpose We aimed to investigate association between bibliometric parameters, reporting and methodological quality of vascular and endovascular surgery randomised controlled trials. Methods The most recent 75 and oldest 75 randomised controlled trials published in leading journals over a 10-year period were identified. The reporting quality was analysed using the CONSORT statement, and methodological quality with the Intercollegiate Guidelines Network checklist. We used exploratory univariate and multivariable linear regression analysis to investigate associations. Findings Bibliometric parameters such as type of journal, study design reported in title, number of pages; external funding, industry sponsoring and number of citations are associated with reporting quality. Moreover, parameters such as type of journal, subject area and study design reported in title are associated with methodological quality. Conclusions The bibliometric parameters of randomised controlled trials may be independent predictors for their reporting and methodological quality. Moreover, the reporting quality of randomised controlled trials is associated with their methodological quality and vice versa.

Randomised controlled trial of reflexology for menopausal symptoms.

PubMed

Williamson, Jan; White, Adrian; Hart, Anna; Ernst, Edzard

2002-09-01

Clinical experience suggests that reflexology may have beneficial effects on the symptoms occurring in menopausal women, particularly psychological symptoms. This study aims to examine that effect rigorously. Randomised controlled trial with two parallel arms. School of Complementary Health in Exeter, Devon, UK. Seventy-six women, aged between 45 and 60 years, reporting menopausal symptoms. Women were randomised to receive nine sessions of either reflexology or nonspecific foot massage (control) by four qualified reflexologists given over a period of 19 weeks. The Women's Health Questionnaire (WHQ), the primary measures being the subscores for anxiety and depression. Severity (visual analogue scale, VAS) and frequency of flushes and night sweats. Mean (SD) scores for anxiety fell from 0.43 (0.29) to 0.22 (0.25) in the reflexology group and from 0.37 (0.27) to 0.27 (0.29) in the control group over the course of treatment. Mean (SD) scores for depression fell from 0.37 (0.25) to 0.20 (0.24) in the reflexology group and from 0.36 (0.23) to 0.20 (0.21) in the control (foot massage) group over the same period. For both scores there was strong evidence of a time effect (P < 0.001) but no evidence of a time-group interaction (P > 0.2). Similar changes were found for severity of hot flushes and night sweats. In the control group, 14/37 believed they had not received true reflexology. Foot reflexology was not shown to be more effective than non-specific foot massage in the treatment of psychological symptoms occurring during the menopause.

Robust Control for The G-Limit Microgravity Vibration Isolation System

NASA Technical Reports Server (NTRS)

Whorton, Mark S.

2004-01-01

Many microgravity science experiments need an active isolation system to provide a sufficiently quiescent acceleration environment. The g-LIMIT vibration isolation system will provide isolation for Microgravity Science Glovebox experiments in the International Space Station. While standard control system technologies have been demonstrated for these applications, modern control methods have the potential for meeting performance requirements while providing robust stability in the presence of parametric uncertainties that are characteristic of microgravity vibration isolation systems. While H2 and H infinity methods are well established, neither provides the levels of attenuation performance and robust stability in a compensator with low order. Mixed H2/mu controllers provide a means for maximizing robust stability for a given level of mean-square nominal performance while directly optimizing for controller order constraints. This paper demonstrates the benefit of mixed norm design from the perspective of robustness to parametric uncertainties and controller order for microgravity vibration isolation. A nominal performance metric analogous to the mu measure for robust stability assessment is also introduced in order to define an acceptable trade space from which different control methodologies can be compared.

Concordance and acceptability of electric stimulation therapy: a randomised controlled trial.

PubMed

Miller, C; McGuiness, W; Wilson, S; Cooper, K; Swanson, T; Rooney, D; Piller, N; Woodward, M

2017-08-02

A pilot single-blinded randomised controlled trial (RCT) was conducted to examine concordance with and acceptability of electric stimulation therapy (EST) in patients with venous leg ulcers (VLUs) who had not tolerated moderate to high compression. Participants were randomised to the intervention group (n=15) or a placebo control group (n=8) in which EST was used four times daily for 20 minutes per session. Participants were monitored for eight weeks during which time concordance with the treatment and perceptions of the treatment were assessed. Concordance with the total recommended treatment time was 71.4% for the intervention group and 82.9% for the control group; a difference that was not statistically significant. Participants rated EST as acceptable (84.6% intervention; 83.3% control), only two participants, both from the placebo control group, would not be willing to use EST again. The majority considered EST easier to use than compression (68.4%). EST was a practical and acceptable treatment among people who have been unable to tolerate moderate to high compression therapy.

Optimization of robustness of interdependent network controllability by redundant design

PubMed Central

2018-01-01

Controllability of complex networks has been a hot topic in recent years. Real networks regarded as interdependent networks are always coupled together by multiple networks. The cascading process of interdependent networks including interdependent failure and overload failure will destroy the robustness of controllability for the whole network. Therefore, the optimization of the robustness of interdependent network controllability is of great importance in the research area of complex networks. In this paper, based on the model of interdependent networks constructed first, we determine the cascading process under different proportions of node attacks. Then, the structural controllability of interdependent networks is measured by the minimum driver nodes. Furthermore, we propose a parameter which can be obtained by the structure and minimum driver set of interdependent networks under different proportions of node attacks and analyze the robustness for interdependent network controllability. Finally, we optimize the robustness of interdependent network controllability by redundant design including node backup and redundancy edge backup and improve the redundant design by proposing different strategies according to their cost. Comparative strategies of redundant design are conducted to find the best strategy. Results shows that node backup and redundancy edge backup can indeed decrease those nodes suffering from failure and improve the robustness of controllability. Considering the cost of redundant design, we should choose BBS (betweenness-based strategy) or DBS (degree based strategy) for node backup and HDF(high degree first) for redundancy edge backup. Above all, our proposed strategies are feasible and effective at improving the robustness of interdependent network controllability. PMID:29438426

Integrated direct/indirect adaptive robust motion trajectory tracking control of pneumatic cylinders

NASA Astrophysics Data System (ADS)

Meng, Deyuan; Tao, Guoliang; Zhu, Xiaocong

2013-09-01

This paper studies the precision motion trajectory tracking control of a pneumatic cylinder driven by a proportional-directional control valve. An integrated direct/indirect adaptive robust controller is proposed. The controller employs a physical model based indirect-type parameter estimation to obtain reliable estimates of unknown model parameters, and utilises a robust control method with dynamic compensation type fast adaptation to attenuate the effects of parameter estimation errors, unmodelled dynamics and disturbances. Due to the use of projection mapping, the robust control law and the parameter adaption algorithm can be designed separately. Since the system model uncertainties are unmatched, the recursive backstepping technology is adopted to design the robust control law. Extensive comparative experimental results are presented to illustrate the effectiveness of the proposed controller and its performance robustness to parameter variations and sudden disturbances.

Density control in ITER: an iterative learning control and robust control approach

NASA Astrophysics Data System (ADS)

Ravensbergen, T.; de Vries, P. C.; Felici, F.; Blanken, T. C.; Nouailletas, R.; Zabeo, L.

2018-01-01

Plasma density control for next generation tokamaks, such as ITER, is challenging because of multiple reasons. The response of the usual gas valve actuators in future, larger fusion devices, might be too slow for feedback control. Both pellet fuelling and the use of feedforward-based control may help to solve this problem. Also, tight density limits arise during ramp-up, due to operational limits related to divertor detachment and radiative collapses. As the number of shots available for controller tuning will be limited in ITER, in this paper, iterative learning control (ILC) is proposed to determine optimal feedforward actuator inputs based on tracking errors, obtained in previous shots. This control method can take the actuator and density limits into account and can deal with large actuator delays. However, a purely feedforward-based density control may not be sufficient due to the presence of disturbances and shot-to-shot differences. Therefore, robust control synthesis is used to construct a robustly stabilizing feedback controller. In simulations, it is shown that this combined controller strategy is able to achieve good tracking performance in the presence of shot-to-shot differences, tight constraints, and model mismatches.

Development of a practical approach to expert elicitation for randomised controlled trials with missing health outcomes: Application to the IMPROVE trial.

PubMed

Mason, Alexina J; Gomes, Manuel; Grieve, Richard; Ulug, Pinar; Powell, Janet T; Carpenter, James

2017-08-01

The analyses of randomised controlled trials with missing data typically assume that, after conditioning on the observed data, the probability of missing data does not depend on the patient's outcome, and so the data are 'missing at random' . This assumption is usually implausible, for example, because patients in relatively poor health may be more likely to drop out. Methodological guidelines recommend that trials require sensitivity analysis, which is best informed by elicited expert opinion, to assess whether conclusions are robust to alternative assumptions about the missing data. A major barrier to implementing these methods in practice is the lack of relevant practical tools for eliciting expert opinion. We develop a new practical tool for eliciting expert opinion and demonstrate its use for randomised controlled trials with missing data. We develop and illustrate our approach for eliciting expert opinion with the IMPROVE trial (ISRCTN 48334791), an ongoing multi-centre randomised controlled trial which compares an emergency endovascular strategy versus open repair for patients with ruptured abdominal aortic aneurysm. In the IMPROVE trial at 3 months post-randomisation, 21% of surviving patients did not complete health-related quality of life questionnaires (assessed by EQ-5D-3L). We address this problem by developing a web-based tool that provides a practical approach for eliciting expert opinion about quality of life differences between patients with missing versus complete data. We show how this expert opinion can define informative priors within a fully Bayesian framework to perform sensitivity analyses that allow the missing data to depend upon unobserved patient characteristics. A total of 26 experts, of 46 asked to participate, completed the elicitation exercise. The elicited quality of life scores were lower on average for the patients with missing versus complete data, but there was considerable uncertainty in these elicited values. The missing at

Development of a practical approach to expert elicitation for randomised controlled trials with missing health outcomes: Application to the IMPROVE trial

PubMed Central

Mason, Alexina J; Gomes, Manuel; Grieve, Richard; Ulug, Pinar; Powell, Janet T; Carpenter, James

2017-01-01

Background/aims: The analyses of randomised controlled trials with missing data typically assume that, after conditioning on the observed data, the probability of missing data does not depend on the patient’s outcome, and so the data are ‘missing at random’ . This assumption is usually implausible, for example, because patients in relatively poor health may be more likely to drop out. Methodological guidelines recommend that trials require sensitivity analysis, which is best informed by elicited expert opinion, to assess whether conclusions are robust to alternative assumptions about the missing data. A major barrier to implementing these methods in practice is the lack of relevant practical tools for eliciting expert opinion. We develop a new practical tool for eliciting expert opinion and demonstrate its use for randomised controlled trials with missing data. Methods: We develop and illustrate our approach for eliciting expert opinion with the IMPROVE trial (ISRCTN 48334791), an ongoing multi-centre randomised controlled trial which compares an emergency endovascular strategy versus open repair for patients with ruptured abdominal aortic aneurysm. In the IMPROVE trial at 3 months post-randomisation, 21% of surviving patients did not complete health-related quality of life questionnaires (assessed by EQ-5D-3L). We address this problem by developing a web-based tool that provides a practical approach for eliciting expert opinion about quality of life differences between patients with missing versus complete data. We show how this expert opinion can define informative priors within a fully Bayesian framework to perform sensitivity analyses that allow the missing data to depend upon unobserved patient characteristics. Results: A total of 26 experts, of 46 asked to participate, completed the elicitation exercise. The elicited quality of life scores were lower on average for the patients with missing versus complete data, but there was considerable uncertainty in

Teacher Pupil Control Ideology and Behavior as Predictors of Classroom Robustness.

ERIC Educational Resources Information Center

Estep, Linda E.; And Others

1980-01-01

It was hypothesized that confrontations between a strict teacher and misbehaving students would add drama and robustness to the classroom. In 88 secondary classrooms, robustness and teacher's control ideology and behavior were measured. The hypothesis was rejected; humanistic control behavior related to high robustness. A companion elementary…

Robust fast controller design via nonlinear fractional differential equations.

PubMed

Zhou, Xi; Wei, Yiheng; Liang, Shu; Wang, Yong

2017-07-01

A new method for linear system controller design is proposed whereby the closed-loop system achieves both robustness and fast response. The robustness performance considered here means the damping ratio of closed-loop system can keep its desired value under system parameter perturbation, while the fast response, represented by rise time of system output, can be improved by tuning the controller parameter. We exploit techniques from both the nonlinear systems control and the fractional order systems control to derive a novel nonlinear fractional order controller. For theoretical analysis of the closed-loop system performance, two comparison theorems are developed for a class of fractional differential equations. Moreover, the rise time of the closed-loop system can be estimated, which facilitates our controller design to satisfy the fast response performance and maintain the robustness. Finally, numerical examples are given to illustrate the effectiveness of our methods. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Robust control of multi-jointed arm with a decentralized autonomous control mechanism

NASA Technical Reports Server (NTRS)

Kimura, Shinichi; Miyazaki, Ken; Suzuki, Yoshiaki

1994-01-01

A decentralized autonomous control mechanism applied to the control of three dimensional manipulators and its robustness to partial damage was assessed by computer simulation. Decentralized control structures are believed to be quite robust to time delay between the operator and the target system. A 10-jointed manipulator based on our control mechanism was able to continue its positioning task in three-dimensional space without revision of the control program, even after some of its joints were damaged. These results suggest that this control mechanism can be effectively applied to space telerobots, which are associated with serious time delay between the operator and the target system, and which cannot be easily repaired after being partially damaged.

Two parallel, pragmatic, UK multicentre, randomised controlled trials comparing surgical options for upper compartment (vault or uterine) pelvic organ prolapse (the VUE Study): study protocol for a randomised controlled trial.

PubMed

Glazener, Cathryn; Constable, Lynda; Hemming, Christine; Breeman, Suzanne; Elders, Andrew; Cooper, Kevin; Freeman, Robert; Smith, Anthony R B; Hagen, Suzanne; McDonald, Alison; McPherson, Gladys; Montgomery, Isobel; Kilonzo, Mary; Boyers, Dwayne; Goulao, Beatriz; Norrie, John

2016-09-08

One in three women who have a prolapse operation will go on to have another operation, though not necessarily in the same compartment. Surgery can result in greater impairment of quality of life than the original prolapse itself (such as the development of new-onset urinary incontinence, or prolapse at a different site). Anterior and posterior prolapse surgery is most common (90 % of operations), but around 43 % of women also have a uterine (34 %) or vault (9 %) procedure at the same time. There is not enough evidence from randomised controlled trials (RCTs) to guide management of vault or uterine prolapse. The Vault or Uterine prolapse surgery Evaluation (VUE) study aims to assess the surgical management of upper compartment pelvic organ prolapse (POP) in terms of clinical effectiveness, cost-effectiveness and adverse events. VUE is two parallel, pragmatic, UK multicentre, RCTs (Uterine Trial and Vault Trial). Eligible for inclusion are women with vault or uterine prolapse: requiring a surgical procedure, suitable for randomisation and willing to be randomised. Randomisation will be computer-allocated separately for each trial, minimised on: requiring concomitant anterior and/or posterior POP surgery or not, concomitant incontinence surgery or not, age (under 60 years or 60 years and older) and surgeon. Participants will be randomly assigned, with equal probability to intervention or control arms in either the Uterine Trial or the Vault Trial. Uterine Trial participants will receive either a vaginal hysterectomy or a uterine preservation procedure. Vault Trial participants will receive either a vaginal sacrospinous fixation or an abdominal sacrocolpopexy. Participants will be followed up by postal questionnaires (6 months post surgery and 12 months post randomisation) and also reviewed in clinic 12 months post surgery. The primary outcome is the participant-reported Pelvic Organ Prolapse Symptom Score (POP-SS) at 12 months post randomisation

Does hospital at home for palliative care facilitate death at home? Randomised controlled trial

PubMed Central

Grande, Gunn E; Todd, Chris J; Barclay, Stephen I G; Farquhar, Morag C

1999-01-01

Objective To evaluate the impact on place of death of a hospital at home service for palliative care. Design Pragmatic randomised controlled trial. Setting Former Cambridge health district. Participants 229 patients referred to the hospital at home service; 43 randomised to control group (standard care), 186 randomised to hospital at home. Intervention Hospital at home versus standard care. Main outcome measures Place of death. Results Twenty five (58%) control patients died at home compared with 124 (67%) patients allocated to hospital at home. This difference was not significant; intention to treat analysis did not show that hospital at home increased the number of deaths at home. Seventy three patients randomised to hospital at home were not admitted to the service. Patients admitted to hospital at home were significantly more likely to die at home (88/113; 78%) than control patients. It is not possible to determine whether this was due to hospital at home itself or other characteristics of the patients admitted to the service. The study attained less statistical power than initially planned. Conclusion In a locality with good provision of standard community care we could not show that hospital at home allowed more patients to die at home, although neither does the study refute this. Problems relating to recruitment, attrition, and the vulnerability of the patient group make randomised controlled trials in palliative care difficult. While these difficulties have to be recognised they are not insurmountable with the appropriate resourcing and setting. Key messagesTerminally ill patients allocated to hospital at home were no more likely to die at home than patients receiving standard careAlthough the subsample of patients actually admitted to hospital at home did show a significant increase in likelihood of dying at home, whether this was due to the service itself or the characteristics of patients admitted to hospital at home could not be determinedThe need to

Does telecare prolong community living in dementia? A study protocol for a pragmatic, randomised controlled trial

PubMed Central

2013-01-01

Background Assistive technology and telecare (ATT) are relatively new ways of delivering care and support to people with social care needs. It is claimed that ATT reduces the need for community care, prevents unnecessary hospital admission, and delays or prevents admission into residential or nursing care. The current economic situation in England has renewed interest in ATT instead of community care packages. However, at present, the evidence base to support claims about the impact and effectiveness of ATT is limited, despite its potential to mitigate the high financial cost of caring for people with dementia and the social and psychological cost to unpaid carers. Method/design ATTILA (Assistive Technology and Telecare to maintain Independent Living At Home for People with Dementia) is a pragmatic, multi-centre, randomised controlled trial over 104 weeks that compares outcomes for people with dementia who receive ATT and those who receive equivalent community services but not ATT. The study hypothesis is that fewer people in the ATT group will go into institutional care over the 4-year period for which the study is funded. The study aims to recruit 500 participants, living in community settings, with dementia or significant cognitive impairment, who have recently been referred to social services. Primary outcome measures are time in days from randomisation to institutionalisation and cost effectiveness. Secondary outcomes are caregiver burden, health-related quality of life in carers, number and severity of serious adverse events, and data on acceptability, applicability and reliability of ATT intervention packages. Assessments will be undertaken in weeks 0 (baseline), 12, 24, 52 and 104 or until institutionalisation or withdrawal of the participant from the trial. Discussion In a time of financial austerity, CASSRs in England are increasingly turning to ATT in the belief that it will deliver good outcomes for less money. There is an absence of robust evidence for

A Computational Framework to Control Verification and Robustness Analysis

NASA Technical Reports Server (NTRS)

Crespo, Luis G.; Kenny, Sean P.; Giesy, Daniel P.

2010-01-01

This paper presents a methodology for evaluating the robustness of a controller based on its ability to satisfy the design requirements. The framework proposed is generic since it allows for high-fidelity models, arbitrary control structures and arbitrary functional dependencies between the requirements and the uncertain parameters. The cornerstone of this contribution is the ability to bound the region of the uncertain parameter space where the degradation in closed-loop performance remains acceptable. The size of this bounding set, whose geometry can be prescribed according to deterministic or probabilistic uncertainty models, is a measure of robustness. The robustness metrics proposed herein are the parametric safety margin, the reliability index, the failure probability and upper bounds to this probability. The performance observed at the control verification setting, where the assumptions and approximations used for control design may no longer hold, will fully determine the proposed control assessment.

Optimal robust control strategy of a solid oxide fuel cell system

NASA Astrophysics Data System (ADS)

Wu, Xiaojuan; Gao, Danhui

2018-01-01

Optimal control can ensure system safe operation with a high efficiency. However, only a few papers discuss optimal control strategies for solid oxide fuel cell (SOFC) systems. Moreover, the existed methods ignore the impact of parameter uncertainty on system instantaneous performance. In real SOFC systems, several parameters may vary with the variation of operation conditions and can not be identified exactly, such as load current. Therefore, a robust optimal control strategy is proposed, which involves three parts: a SOFC model with parameter uncertainty, a robust optimizer and robust controllers. During the model building process, boundaries of the uncertain parameter are extracted based on Monte Carlo algorithm. To achieve the maximum efficiency, a two-space particle swarm optimization approach is employed to obtain optimal operating points, which are used as the set points of the controllers. To ensure the SOFC safe operation, two feed-forward controllers and a higher-order robust sliding mode controller are presented to control fuel utilization ratio, air excess ratio and stack temperature afterwards. The results show the proposed optimal robust control method can maintain the SOFC system safe operation with a maximum efficiency under load and uncertainty variations.

Robustness results in LQG based multivariable control designs

NASA Technical Reports Server (NTRS)

Lehtomaki, N. A.; Sandell, N. R., Jr.; Athans, M.

1980-01-01

The robustness of control systems with respect to model uncertainty is considered using simple frequency domain criteria. Results are derived under a common framework in which the minimum singular value of the return difference transfer matrix is the key quantity. In particular, the LQ and LQG robustness results are discussed.

Robust reliable sampled-data control for switched systems with application to flight control

NASA Astrophysics Data System (ADS)

Sakthivel, R.; Joby, Maya; Shi, P.; Mathiyalagan, K.

2016-11-01

This paper addresses the robust reliable stabilisation problem for a class of uncertain switched systems with random delays and norm bounded uncertainties. The main aim of this paper is to obtain the reliable robust sampled-data control design which involves random time delay with an appropriate gain control matrix for achieving the robust exponential stabilisation for uncertain switched system against actuator failures. In particular, the involved delays are assumed to be randomly time-varying which obeys certain mutually uncorrelated Bernoulli distributed white noise sequences. By constructing an appropriate Lyapunov-Krasovskii functional (LKF) and employing an average-dwell time approach, a new set of criteria is derived for ensuring the robust exponential stability of the closed-loop switched system. More precisely, the Schur complement and Jensen's integral inequality are used in derivation of stabilisation criteria. By considering the relationship among the random time-varying delay and its lower and upper bounds, a new set of sufficient condition is established for the existence of reliable robust sampled-data control in terms of solution to linear matrix inequalities (LMIs). Finally, an illustrative example based on the F-18 aircraft model is provided to show the effectiveness of the proposed design procedures.

Robustness of Controllability for Networks Based on Edge-Attack

PubMed Central

Nie, Sen; Wang, Xuwen; Zhang, Haifeng; Li, Qilang; Wang, Binghong

2014-01-01

We study the controllability of networks in the process of cascading failures under two different attacking strategies, random and intentional attack, respectively. For the highest-load edge attack, it is found that the controllability of Erdős-Rényi network, that with moderate average degree, is less robust, whereas the Scale-free network with moderate power-law exponent shows strong robustness of controllability under the same attack strategy. The vulnerability of controllability under random and intentional attacks behave differently with the increasing of removal fraction, especially, we find that the robustness of control has important role in cascades for large removal fraction. The simulation results show that for Scale-free networks with various power-law exponents, the network has larger scale of cascades do not mean that there will be more increments of driver nodes. Meanwhile, the number of driver nodes in cascading failures is also related to the edges amount in strongly connected components. PMID:24586507

Robustness of controllability for networks based on edge-attack.

PubMed

Nie, Sen; Wang, Xuwen; Zhang, Haifeng; Li, Qilang; Wang, Binghong

2014-01-01

We study the controllability of networks in the process of cascading failures under two different attacking strategies, random and intentional attack, respectively. For the highest-load edge attack, it is found that the controllability of Erdős-Rényi network, that with moderate average degree, is less robust, whereas the Scale-free network with moderate power-law exponent shows strong robustness of controllability under the same attack strategy. The vulnerability of controllability under random and intentional attacks behave differently with the increasing of removal fraction, especially, we find that the robustness of control has important role in cascades for large removal fraction. The simulation results show that for Scale-free networks with various power-law exponents, the network has larger scale of cascades do not mean that there will be more increments of driver nodes. Meanwhile, the number of driver nodes in cascading failures is also related to the edges amount in strongly connected components.

Robust Optimal Adaptive Control Method with Large Adaptive Gain

NASA Technical Reports Server (NTRS)

Nguyen, Nhan T.

2009-01-01

In the presence of large uncertainties, a control system needs to be able to adapt rapidly to regain performance. Fast adaptation is referred to the implementation of adaptive control with a large adaptive gain to reduce the tracking error rapidly. However, a large adaptive gain can lead to high-frequency oscillations which can adversely affect robustness of an adaptive control law. A new adaptive control modification is presented that can achieve robust adaptation with a large adaptive gain without incurring high-frequency oscillations as with the standard model-reference adaptive control. The modification is based on the minimization of the Y2 norm of the tracking error, which is formulated as an optimal control problem. The optimality condition is used to derive the modification using the gradient method. The optimal control modification results in a stable adaptation and allows a large adaptive gain to be used for better tracking while providing sufficient stability robustness. Simulations were conducted for a damaged generic transport aircraft with both standard adaptive control and the adaptive optimal control modification technique. The results demonstrate the effectiveness of the proposed modification in tracking a reference model while maintaining a sufficient time delay margin.

Ultrasound in management of rheumatoid arthritis: ARCTIC randomised controlled strategy trial

PubMed Central

Aga, Anna-Birgitte; Olsen, Inge Christoffer; Lillegraven, Siri; Hammer, Hilde B; Uhlig, Till; Fremstad, Hallvard; Madland, Tor Magne; Lexberg, Åse Stavland; Haukeland, Hilde; Rødevand, Erik; Høili, Christian; Stray, Hilde; Noraas, Anne; Hansen, Inger Johanne Widding; Bakland, Gunnstein; Nordberg, Lena Bugge; van der Heijde, Désirée; Kvien, Tore K

2016-01-01

Objective To determine whether a treatment strategy based on structured ultrasound assessment would lead to improved outcomes in rheumatoid arthritis, compared with a conventional strategy. Design Multicentre, open label, two arm, parallel group, randomised controlled strategy trial. Setting Ten rheumatology departments and one specialist centre in Norway, from September 2010 to September 2015. Participants 238 patients were recruited between September 2010 and April 2013, of which 230 (141 (61%) female) received the allocated intervention and were analysed for the primary outcome. The main inclusion criteria were age 18-75 years, fulfilment of the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for rheumatoid arthritis, disease modifying anti-rheumatic drug naivety with indication for disease modifying drug therapy, and time from first patient reported swollen joint less than two years. Patients with abnormal kidney or liver function or major comorbidities were excluded. Interventions 122 patients were randomised to an ultrasound tight control strategy targeting clinical and imaging remission, and 116 patients were randomised to a conventional tight control strategy targeting clinical remission. Patients in both arms were treated according to the same disease modifying anti-rheumatic drug escalation strategy, with 13 visits over two years. Main outcome measures The primary endpoint was the proportion of patients with a combination between 16 and 24 months of clinical remission, no swollen joints, and non-progression of radiographic joint damage. Secondary outcomes included measures of disease activity, radiographic progression, functioning, quality of life, and adverse events. All participants who attended at least one follow-up visit were included in the full analysis set. Results 26 (22%) of the 118 analysed patients in the ultrasound tight control arm and 21 (19%) of the 112 analysed patients in the

Robust model predictive control for constrained continuous-time nonlinear systems

NASA Astrophysics Data System (ADS)

Sun, Tairen; Pan, Yongping; Zhang, Jun; Yu, Haoyong

2018-02-01

In this paper, a robust model predictive control (MPC) is designed for a class of constrained continuous-time nonlinear systems with bounded additive disturbances. The robust MPC consists of a nonlinear feedback control and a continuous-time model-based dual-mode MPC. The nonlinear feedback control guarantees the actual trajectory being contained in a tube centred at the nominal trajectory. The dual-mode MPC is designed to ensure asymptotic convergence of the nominal trajectory to zero. This paper extends current results on discrete-time model-based tube MPC and linear system model-based tube MPC to continuous-time nonlinear model-based tube MPC. The feasibility and robustness of the proposed robust MPC have been demonstrated by theoretical analysis and applications to a cart-damper springer system and a one-link robot manipulator.

Robust decentralized power system controller design: Integrated approach

NASA Astrophysics Data System (ADS)

Veselý, Vojtech

2017-09-01

A unique approach to the design of gain scheduled controller (GSC) is presented. The proposed design procedure is based on the Bellman-Lyapunov equation, guaranteed cost and robust stability conditions using the parameter dependent quadratic stability approach. The obtained feasible design procedures for robust GSC design are in the form of BMI with guaranteed convex stability conditions. The obtained design results and their properties are illustrated in the simultaneously design of controllers for simple model (6-order) turbogenerator. The results of the obtained design procedure are a PI automatic voltage regulator (AVR) for synchronous generator, a PI governor controller and a power system stabilizer for excitation system.

Psychosocial consequences in the Danish randomised controlled lung cancer screening trial (DLCST).

PubMed

Rasmussen, Jakob F; Siersma, V; Pedersen, J H; Brodersen, J

2015-01-01

To measure the psychosocial consequences in the Danish lung cancer screening trial (DLCST) and compare those between the computed tomography (CT) group and the control group. This study was a single centre randomised controlled trial with five annual screening rounds. Healthy current or former heavy smokers aged 50-70 years (men and women) were randomised 1:1 to a CT group and a control group. Heavy smokers were defined by having smoked ≥20 pack years and former smokers by being abstinent ≤10 years. Both groups were invited annually to the screening clinic to complete the validated lung-cancer-specific questionnaire consequences of screening lung cancer (COS-LC). The CT group was also offered a low dose CT scan of the lungs. The COS-LC measures nine scales with psychosocial properties: Anxiety, Behaviour, Dejection, Negative impact on sleep, Self-blame, Focus on Airway Symptoms, Stigmatisation, Introvert, and Harm of Smoking. 4104 participants were randomised to the DLCST and the COS-LC completion rates for the CT group and the control group were 95.5% and 73.6%, respectively. There was a significant increase in negative psychosocial consequences from baseline through rounds 2-5 for both the CT group and the control group (mean increase >0, p<.0001 for 3 of 4 possible scales). During rounds 2-5 the control group experienced significantly more negative psychosocial consequences in seven of nine scales compared with the CT group (mean Δ score >0 and p<.033). Lung cancer CT-screening trials induced more negative psychosocial reactions in both the CT group and the control group compared with the baseline psychosocial profile. The CT group experienced less negative psychosocial consequences compared with the control group, which might be explained by reassurance among those with normal screening results. ClinicalTrials.gov: NCT00496977. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Percutaneous coronary intervention in stable angina (ORBITA): a double-blind, randomised controlled trial.

PubMed

Al-Lamee, Rasha; Thompson, David; Dehbi, Hakim-Moulay; Sen, Sayan; Tang, Kare; Davies, John; Keeble, Thomas; Mielewczik, Michael; Kaprielian, Raffi; Malik, Iqbal S; Nijjer, Sukhjinder S; Petraco, Ricardo; Cook, Christopher; Ahmad, Yousif; Howard, James; Baker, Christopher; Sharp, Andrew; Gerber, Robert; Talwar, Suneel; Assomull, Ravi; Mayet, Jamil; Wensel, Roland; Collier, David; Shun-Shin, Matthew; Thom, Simon A; Davies, Justin E; Francis, Darrel P

2018-01-06

Symptomatic relief is the primary goal of percutaneous coronary intervention (PCI) in stable angina and is commonly observed clinically. However, there is no evidence from blinded, placebo-controlled randomised trials to show its efficacy. ORBITA is a blinded, multicentre randomised trial of PCI versus a placebo procedure for angina relief that was done at five study sites in the UK. We enrolled patients with severe (≥70%) single-vessel stenoses. After enrolment, patients received 6 weeks of medication optimisation. Patients then had pre-randomisation assessments with cardiopulmonary exercise testing, symptom questionnaires, and dobutamine stress echocardiography. Patients were randomised 1:1 to undergo PCI or a placebo procedure by use of an automated online randomisation tool. After 6 weeks of follow-up, the assessments done before randomisation were repeated at the final assessment. The primary endpoint was difference in exercise time increment between groups. All analyses were based on the intention-to-treat principle and the study population contained all participants who underwent randomisation. This study is registered with ClinicalTrials.gov, number NCT02062593. ORBITA enrolled 230 patients with ischaemic symptoms. After the medication optimisation phase and between Jan 6, 2014, and Aug 11, 2017, 200 patients underwent randomisation, with 105 patients assigned PCI and 95 assigned the placebo procedure. Lesions had mean area stenosis of 84·4% (SD 10·2), fractional flow reserve of 0·69 (0·16), and instantaneous wave-free ratio of 0·76 (0·22). There was no significant difference in the primary endpoint of exercise time increment between groups (PCI minus placebo 16·6 s, 95% CI -8·9 to 42·0, p=0·200). There were no deaths. Serious adverse events included four pressure-wire related complications in the placebo group, which required PCI, and five major bleeding events, including two in the PCI group and three in the placebo group. In patients with

Gut-directed hypnotherapy for irritable bowel syndrome: piloting a primary care-based randomised controlled trial

PubMed Central

Roberts, Lesley; Wilson, Sue; Singh, Sukhdev; Roalfe, Andrea; Greenfield, Sheila

2006-01-01

Background In western populations irritable bowel syndrome (IBS) affects between 10% and 30% of the population and has a significant effect on quality of life. It generates a substantial workload in both primary and secondary care and has significant cost implications. Gut-directed hypnotherapy has been demonstrated to alleviate symptoms and improve quality of life but has not been assessed outside of secondary and tertiary referral centres. Aim To assess the effectiveness of gut-directed hypnotherapy as a complementary therapy in the management of IBS. Design of study Randomised controlled trial. Setting Primary care patients aged 18–65 years inclusive, with a diagnosis of IBS of greater than 6 weeks' duration and having failed conventional management, located in South Staffordshire and North Birmingham, UK. Method Intervention patients received five sessions of hypnotherapy in addition to their usual management. Control patients received usual management alone. Data regarding symptoms and quality of life were collected at baseline and again 3, 6, and 12 months post-randomisation. Results Both groups demonstrated a significant improvement in all symptom dimensions and quality of life over 12 months. At 3 months the intervention group had significantly greater improvements in pain, diarrhoea and overall symptom scores (P<0.05). No significant differences between groups in quality of life were identified. No differences were maintained over time. Intervention patients, however, were significantly less likely to require medication, and the majority described an improvement in their condition. Conclusions Gut-directed hypnotherapy benefits patients via symptom reduction and reduced medication usage, although the lack of significant difference between groups beyond 3 months prohibits its general introduction without additional evidence. A large trial incorporating robust economic analysis is, therefore, urgently recommended. PMID:16464325

Effect of interaction strength on robustness of controlling edge dynamics in complex networks

NASA Astrophysics Data System (ADS)

Pang, Shao-Peng; Hao, Fei

2018-05-01

Robustness plays a critical role in the controllability of complex networks to withstand failures and perturbations. Recent advances in the edge controllability show that the interaction strength among edges plays a more important role than network structure. Therefore, we focus on the effect of interaction strength on the robustness of edge controllability. Using three categories of all edges to quantify the robustness, we develop a universal framework to evaluate and analyze the robustness in complex networks with arbitrary structures and interaction strengths. Applying our framework to a large number of model and real-world networks, we find that the interaction strength is a dominant factor for the robustness in undirected networks. Meanwhile, the strongest robustness and the optimal edge controllability in undirected networks can be achieved simultaneously. Different from the case of undirected networks, the robustness in directed networks is determined jointly by the interaction strength and the network's degree distribution. Moreover, a stronger robustness is usually associated with a larger number of driver nodes required to maintain full control in directed networks. This prompts us to provide an optimization method by adjusting the interaction strength to optimize the robustness of edge controllability.

Antenatal peer support workers and initiation of breast feeding: cluster randomised controlled trial.

PubMed

MacArthur, Christine; Jolly, Kate; Ingram, Lucy; Freemantle, Nick; Dennis, Cindy-Lee; Hamburger, Ros; Brown, Julia; Chambers, Jackie; Khan, Khalid

2009-01-30

To assess the effectiveness of an antenatal service using community based breastfeeding peer support workers on initiation of breast feeding. Cluster randomised controlled trial. Community antenatal clinics in one primary care trust in a multiethnic, deprived population. 66 antenatal clinics with 2511 pregnant women: 33 clinics including 1140 women were randomised to receive the peer support worker service and 33 clinics including 1371 women were randomised to receive standard care. An antenatal peer support worker service planned to comprise a minimum of two contacts with women to provide advice, information, and support from approximately 24 weeks' gestation within the antenatal clinic or at home. The trained peer support workers were of similar ethnic and sociodemographic backgrounds to their clinic population. Initiation of breast feeding obtained from computerised maternity records of the hospitals where women from the primary care trust delivered. The sample was multiethnic, with only 9.4% of women being white British, and 70% were in the lowest 10th for deprivation. Most of the contacts with peer support workers took place in the antenatal clinics. Data on initiation of breast feeding were obtained for 2398 of 2511 (95.5%) women (1083/1140 intervention and 1315/1371 controls). The groups did not differ for initiation of breast feeding: 69.0% (747/1083) in the intervention group and 68.1% (896/1315) in the control groups; cluster adjusted odds ratio 1.11 (95% confidence interval 0.87 to 1.43). Ethnicity, parity, and mode of delivery independently predicted initiation of breast feeding, but randomisation to the peer support worker service did not. A universal service for initiation of breast feeding using peer support workers provided within antenatal clinics serving a multiethnic, deprived population was ineffective in increasing initiation rates. Current Controlled Trials ISRCTN16126175.

Personal oral hygiene and dental caries: A systematic review of randomised controlled trials.

PubMed

Hujoel, Philippe Pierre; Hujoel, Margaux Louise A; Kotsakis, Georgios A

2018-05-15

To conduct a systematic review of randomised trials assessing the association between personal oral hygiene and dental caries in the absence of the confounding effects of fluoride. Dental caries continues to affect close to 100% of the global population. There is a century-old conflict on whether dental caries is caused by poor oral hygiene or poorly formed teeth (ie, teeth with dental defects). Resolving this conflict is of significant public health importance as these two hypotheses on dental caries aetiology can lead to different prevention strategies. A systematic search for randomised trials was conducted using predefined criteria in 3 databases. The impact of personal oral hygiene interventions on coronal dental caries incidence was evaluated using random-effects models. Three randomised studies involving a total of 743 participants were included. Personal oral hygiene interventions failed to influence the incidence of dental caries (Δ Decayed, Missing and Filled Surfaces (DFMS) = -0.11; 95% confidence interval: (-0.91, 0.69; P-value < .79)) despite meticulous deplaquing of teeth. There was no significant heterogeneity in the trial results (heterogeneity chi-squared = 1.88, P = .39). The findings were robust to sensitivity analyses, including consideration of the results of nonrandomised studies. Personal oral hygiene in the absence of fluorides has failed to show a benefit in terms of reducing the incidence of dental caries. © 2018 The Authors. Gerodontology published by British Society of Gerodontology, European College of Gerodontology and Geriatric Oral Research Group and John Wiley & Sons Ltd.

Robust attitude control design for spacecraft under assigned velocity and control constraints.

PubMed

Hu, Qinglei; Li, Bo; Zhang, Youmin

2013-07-01

A novel robust nonlinear control design under the constraints of assigned velocity and actuator torque is investigated for attitude stabilization of a rigid spacecraft. More specifically, a nonlinear feedback control is firstly developed by explicitly taking into account the constraints on individual angular velocity components as well as external disturbances. Considering further the actuator misalignments and magnitude deviation, a modified robust least-squares based control allocator is employed to deal with the problem of distributing the previously designed three-axis moments over the available actuators, in which the focus of this control allocation is to find the optimal control vector of actuators by minimizing the worst-case residual error using programming algorithms. The attitude control performance using the controller structure is evaluated through a numerical example. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

The Hawthorne Effect: a randomised, controlled trial

PubMed Central

McCarney, Rob; Warner, James; Iliffe, Steve; van Haselen, Robbert; Griffin, Mark; Fisher, Peter

2007-01-01

Background The 'Hawthorne Effect' may be an important factor affecting the generalisability of clinical research to routine practice, but has been little studied. Hawthorne Effects have been reported in previous clinical trials in dementia but to our knowledge, no attempt has been made to quantify them. Our aim was to compare minimal follow-up to intensive follow-up in participants in a placebo controlled trial of Ginkgo biloba for treating mild-moderate dementia. Methods Participants in a dementia trial were randomised to intensive follow-up (with comprehensive assessment visits at baseline and two, four and six months post randomisation) or minimal follow-up (with an abbreviated assessment at baseline and a full assessment at six months). Our primary outcomes were cognitive functioning (ADAS-Cog) and participant and carer-rated quality of life (QOL-AD). Results We recruited 176 participants, mainly through general practices. The main analysis was based on Intention to treat (ITT), with available data. In the ANCOVA model with baseline score as a co-variate, follow-up group had a significant effect on outcome at six months on the ADAS-Cog score (n = 140; mean difference = -2.018; 95%CI -3.914, -0.121; p = 0.037 favouring the intensive follow-up group), and on participant-rated quality of life score (n = 142; mean difference = -1.382; 95%CI -2.642, -0.122; p = 0.032 favouring minimal follow-up group). There was no significant difference on carer quality of life. Conclusion We found that more intensive follow-up of individuals in a placebo-controlled clinical trial of Ginkgo biloba for treating mild-moderate dementia resulted in a better outcome than minimal follow-up, as measured by their cognitive functioning. Trial registration Current controlled trials: ISRCTN45577048 PMID:17608932

Hepatitis C - Assessment to Treatment Trial (HepCATT) in primary care: study protocol for a cluster randomised controlled trial.

PubMed

Roberts, Kirsty; Macleod, John; Metcalfe, Chris; Simon, Joanne; Horwood, Jeremy; Hollingworth, William; Marlowe, Sharon; Gordon, Fiona H; Muir, Peter; Coleman, Barbara; Vickerman, Peter; Harrison, Graham I; Waldron, Cherry-Ann; Irving, William; Hickman, Matthew

2016-07-29

Public Health England (PHE) estimates that there are upwards of 160,000 individuals in England and Wales with chronic hepatitis C virus (HCV) infection, but until now only around 100,000 laboratory diagnoses have been reported to PHE and of these 28,000 have been treated. Targeted case-finding in primary care is estimated to be cost-effective; however, there has been no robust randomised controlled trial evidence available of specific interventions. Therefore, this study aims to develop and conduct a complex intervention within primary care and to evaluate this approach using a cluster randomised controlled trial. A total of 46 general practices in South West England will be randomised in a 1:1 ratio to receive either a complex intervention comprising: educational training on HCV for the practice; poster and leaflet display in the practice waiting rooms to raise awareness and encourage opportunistic testing; a HCV risk prediction algorithm based on information on possible risk markers in the electronic patient record run using Audit + software (BMJ Informatica). The audit will then be used to recall and offer patients a HCV test. Control practices will follow usual care. The effectiveness of the intervention will be measured by comparing number and rates of HCV testing, the number and proportion of patients testing positive, onward referral, rates of specialist assessment and treatment in control and intervention practices. Intervention costs and health service utilisation will be recorded to estimate the NHS cost per new HCV diagnosis and new HCV patient initiating treatment. Longer-term cost-effectiveness of the intervention in improving quality-adjusted life years (QALYs) will be extrapolated using a pre-existing dynamic health economic model. Patients' and health care workers' experiences and acceptability of the intervention will be explored through semi-structured qualitative interviews. This trial has the potential to make an important impact on patient

Prostate cancer - evidence of exercise and nutrition trial (PrEvENT): study protocol for a randomised controlled feasibility trial.

PubMed

Hackshaw-McGeagh, Lucy; Lane, J Athene; Persad, Raj; Gillatt, David; Holly, Jeff M P; Koupparis, Anthony; Rowe, Edward; Johnston, Lyndsey; Cloete, Jenny; Shiridzinomwa, Constance; Abrams, Paul; Penfold, Chris M; Bahl, Amit; Oxley, Jon; Perks, Claire M; Martin, Richard

2016-03-07

A growing body of observational evidence suggests that nutritional and physical activity interventions are associated with beneficial outcomes for men with prostate cancer, including brisk walking, lycopene intake, increased fruit and vegetable intake and reduced dairy consumption. However, randomised controlled trial data are limited. The 'Prostate Cancer: Evidence of Exercise and Nutrition Trial' investigates the feasibility of recruiting and randomising men diagnosed with localised prostate cancer and eligible for radical prostatectomy to interventions that modify nutrition and physical activity. The primary outcomes are randomisation rates and adherence to the interventions at 6 months following randomisation. The secondary outcomes are intervention tolerability, trial retention, change in prostate specific antigen level, change in diet, change in general physical activity levels, insulin-like growth factor levels, and a range of related outcomes, including quality of life measures. The trial is factorial, randomising men to both a physical activity (brisk walking or control) and nutritional (lycopene supplementation or increased fruit and vegetables with reduced dairy consumption or control) intervention. The trial has two phases: men are enrolled into a cohort study prior to radical prostatectomy, and then consented after radical prostatectomy into a randomised controlled trial. Data are collected at four time points (cohort baseline, true trial baseline and 3 and 6 months post-randomisation). The Prostate Cancer: Evidence of Exercise and Nutrition Trial aims to determine whether men with localised prostate cancer who are scheduled for radical prostatectomy can be recruited into a cohort and subsequently randomised to a 6-month nutrition and physical activity intervention trial. If successful, this feasibility trial will inform a larger trial to investigate whether this population will gain clinical benefit from long-term nutritional and physical activity

A randomised controlled trial of complete denture impression materials.

PubMed

Hyde, T P; Craddock, H L; Gray, J C; Pavitt, S H; Hulme, C; Godfrey, M; Fernandez, C; Navarro-Coy, N; Dillon, S; Wright, J; Brown, S; Dukanovic, G; Brunton, P A

2014-08-01

There is continuing demand for non-implant prosthodontic treatment and yet there is a paucity of high quality Randomised Controlled Trial (RCT) evidence for best practice. The aim of this research was to provide evidence for best practice in prosthodontic impressions by comparing two impression materials in a double-blind, randomised, crossover, controlled, clinical trial. Eighty-five patients were recruited, using published eligibility criteria, to the trial at Leeds Dental Institute, UK. Each patient received two sets of dentures; made using either alginate or silicone impressions. Randomisations determined the order of assessment and order of impressions. The primary outcome was patient blinded preference for unadjusted dentures. Secondary outcomes were patient preference for the adjusted dentures, rating of comfort, stability and chewing efficiency, experience of each impression, and an OHIP-EDENT questionnaire. Seventy-eight (91.8%) patients completed the primary assessment. 53(67.9%) patients preferred dentures made from silicone impressions while 14(17.9%) preferred alginate impressions. 4(5.1%) patients found both dentures equally satisfactory and 7 (9.0%) found both equally unsatisfactory. There was a 50% difference in preference rates (in favour of silicone) (95%CI 32.7-67.3%, p<0.0001). There is significant evidence that dentures made from silicone impressions were preferred by patients. Given the strength of the clinical findings within this paper, dentists should consider choosing silicone rather than alginate as their material of choice for secondary impressions for complete dentures. ISRCTN 01528038. This article forms part of a project for which the author (TPH) won the Senior Clinical Unilever Hatton Award of the International Assocation for Dental Research, Capetown, South Africa, June 2014. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Robust synergetic control design under inputs and states constraints

NASA Astrophysics Data System (ADS)

Rastegar, Saeid; Araújo, Rui; Sadati, Jalil

2018-03-01

In this paper, a novel robust-constrained control methodology for discrete-time linear parameter-varying (DT-LPV) systems is proposed based on a synergetic control theory (SCT) approach. It is shown that in DT-LPV systems without uncertainty, and for any unmeasured bounded additive disturbance, the proposed controller accomplishes the goal of stabilising the system by asymptotically driving the error of the controlled variable to a bounded set containing the origin and then maintaining it there. Moreover, given an uncertain DT-LPV system jointly subject to unmeasured and constrained additive disturbances, and constraints in states, input commands and reference signals (set points), then invariant set theory is used to find an appropriate polyhedral robust invariant region in which the proposed control framework is guaranteed to robustly stabilise the closed-loop system. Furthermore, this is achieved even for the case of varying non-zero control set points in such uncertain DT-LPV systems. The controller is characterised to have a simple structure leading to an easy implementation, and a non-complex design process. The effectiveness of the proposed method and the implications of the controller design on feasibility and closed-loop performance are demonstrated through application examples on the temperature control on a continuous-stirred tank reactor plant, on the control of a real-coupled DC motor plant, and on an open-loop unstable system example.

A robust H∞ control-based hierarchical mode transition control system for plug-in hybrid electric vehicle

NASA Astrophysics Data System (ADS)

Yang, Chao; Jiao, Xiaohong; Li, Liang; Zhang, Yuanbo; Chen, Zheng

2018-01-01

To realize a fast and smooth operating mode transition process from electric driving mode to engine-on driving mode, this paper presents a novel robust hierarchical mode transition control method for a plug-in hybrid electric bus (PHEB) with pre-transmission parallel hybrid powertrain. Firstly, the mode transition process is divided into five stages to clearly describe the powertrain dynamics. Based on the dynamics models of powertrain and clutch actuating mechanism, a hierarchical control structure including two robust H∞ controllers in both upper layer and lower layer is proposed. In upper layer, the demand clutch torque can be calculated by a robust H∞controller considering the clutch engaging time and the vehicle jerk. While in lower layer a robust tracking controller with L2-gain is designed to perform the accurate position tracking control, especially when the parameters uncertainties and external disturbance occur in the clutch actuating mechanism. Simulation and hardware-in-the-loop (HIL) test are carried out in a traditional driving condition of PHEB. Results show that the proposed hierarchical control approach can obtain the good control performance: mode transition time is greatly reduced with the acceptable jerk. Meanwhile, the designed control system shows the obvious robustness with the uncertain parameters and disturbance. Therefore, the proposed approach may offer a theoretical reference for the actual vehicle controller.

Robust Temperature Control of a Thermoelectric Cooler via μ -Synthesis

NASA Astrophysics Data System (ADS)

Kürkçü, Burak; Kasnakoğlu, Coşku

2018-02-01

In this work robust temperature control of a thermoelectric cooler (TEC) via μ -synthesis is studied. An uncertain dynamical model for the TEC that is suitable for robust control methods is derived. The model captures variations in operating point due to current, load and temperature changes. A temperature controller is designed utilizing μ -synthesis, a powerful method guaranteeing robust stability and performance. For comparison two well-known control methods, namely proportional-integral-derivative (PID) and internal model control (IMC), are also realized to benchmark the proposed approach. It is observed that the stability and performance on the nominal model are satisfactory for all cases. On the other hand, under perturbations the responses of PID and IMC deteriorate and even become unstable. In contrast, the μ -synthesis controller succeeds in keeping system stability and achieving good performance under all perturbations within the operating range, while at the same time providing good disturbance rejection.

Financial incentives for smoking cessation in pregnancy: randomised controlled trial.

PubMed

Tappin, David; Bauld, Linda; Purves, David; Boyd, Kathleen; Sinclair, Lesley; MacAskill, Susan; McKell, Jennifer; Friel, Brenda; McConnachie, Alex; de Caestecker, Linda; Tannahill, Carol; Radley, Andrew; Coleman, Tim

2015-01-27

To assess the efficacy of a financial incentive added to routine specialist pregnancy stop smoking services versus routine care to help pregnant smokers quit. Phase II therapeutic exploratory single centre, individually randomised controlled parallel group superiority trial. One large health board area with a materially deprived, inner city population in the west of Scotland, United Kingdom. 612 self reported pregnant smokers in NHS Greater Glasgow and Clyde who were English speaking, at least 16 years of age, less than 24 weeks pregnant, and had an exhaled carbon monoxide breath test result of 7 ppm or more. 306 women were randomised to incentives and 306 to control. The control group received routine care, which was the offer of a face to face appointment to discuss smoking and cessation and, for those who attended and set a quit date, the offer of free nicotine replacement therapy for 10 weeks provided by pharmacy services, and four, weekly support phone calls. The intervention group received routine care plus the offer of up to £400 of shopping vouchers: £50 for attending a face to face appointment and setting a quit date; then another £50 if at four weeks' post-quit date exhaled carbon monoxide confirmed quitting; a further £100 was provided for continued validated abstinence of exhaled carbon monoxide after 12 weeks; a final £200 voucher was provided for validated abstinence of exhaled carbon monoxide at 34-38 weeks' gestation. The primary outcome was cotinine verified cessation at 34-38 weeks' gestation through saliva (<14.2 ng/mL) or urine (<44.7 ng/mL). Secondary outcomes included birth weight, engagement, and self reported quit at four weeks. Recruitment was extended from 12 to 15 months to achieve the target sample size. Follow-up continued until September 2013. Of the 306 women randomised, three controls opted out soon after enrolment; these women did not want their data to be used, leaving 306 intervention and 303 control group participants in the

Matlab as a robust control design tool

NASA Technical Reports Server (NTRS)

Gregory, Irene M.

1994-01-01

This presentation introduces Matlab as a tool used in flight control research. The example used to illustrate some of the capabilities of this software is a robust controller designed for a single stage to orbit air breathing vehicles's ascent to orbit. The global requirements of the controller are to stabilize the vehicle and follow a trajectory in the presence of atmospheric disturbances and strong dynamic coupling between airframe and propulsion.

Practical robustness measures in multivariable control system analysis. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Lehtomaki, N. A.

1981-01-01

The robustness of the stability of multivariable linear time invariant feedback control systems with respect to model uncertainty is considered using frequency domain criteria. Available robustness tests are unified under a common framework based on the nature and structure of model errors. These results are derived using a multivariable version of Nyquist's stability theorem in which the minimum singular value of the return difference transfer matrix is shown to be the multivariable generalization of the distance to the critical point on a single input, single output Nyquist diagram. Using the return difference transfer matrix, a very general robustness theorem is presented from which all of the robustness tests dealing with specific model errors may be derived. The robustness tests that explicitly utilized model error structure are able to guarantee feedback system stability in the face of model errors of larger magnitude than those robustness tests that do not. The robustness of linear quadratic Gaussian control systems are analyzed.

Robust time and frequency domain estimation methods in adaptive control

NASA Technical Reports Server (NTRS)

Lamaire, Richard Orville

1987-01-01

A robust identification method was developed for use in an adaptive control system. The type of estimator is called the robust estimator, since it is robust to the effects of both unmodeled dynamics and an unmeasurable disturbance. The development of the robust estimator was motivated by a need to provide guarantees in the identification part of an adaptive controller. To enable the design of a robust control system, a nominal model as well as a frequency-domain bounding function on the modeling uncertainty associated with this nominal model must be provided. Two estimation methods are presented for finding parameter estimates, and, hence, a nominal model. One of these methods is based on the well developed field of time-domain parameter estimation. In a second method of finding parameter estimates, a type of weighted least-squares fitting to a frequency-domain estimated model is used. The frequency-domain estimator is shown to perform better, in general, than the time-domain parameter estimator. In addition, a methodology for finding a frequency-domain bounding function on the disturbance is used to compute a frequency-domain bounding function on the additive modeling error due to the effects of the disturbance and the use of finite-length data. The performance of the robust estimator in both open-loop and closed-loop situations is examined through the use of simulations.

Optimal and robust control of transition

NASA Technical Reports Server (NTRS)

Bewley, T. R.; Agarwal, R.

1996-01-01

Optimal and robust control theories are used to determine feedback control rules that effectively stabilize a linearly unstable flow in a plane channel. Wall transpiration (unsteady blowing/suction) with zero net mass flux is used as the control. Control algorithms are considered that depend both on full flowfield information and on estimates of that flowfield based on wall skin-friction measurements only. The development of these control algorithms accounts for modeling errors and measurement noise in a rigorous fashion; these disturbances are considered in both a structured (Gaussian) and unstructured ('worst case') sense. The performance of these algorithms is analyzed in terms of the eigenmodes of the resulting controlled systems, and the sensitivity of individual eigenmodes to both control and observation is quantified.

Evaluating the effect of innovative motivation and supervision approaches on community health worker performance and retention in Uganda and Mozambique: study protocol for a randomised controlled trial.

PubMed

Källander, Karin; Strachan, Daniel; Soremekun, Seyi; Hill, Zelee; Lingam, Raghu; Tibenderana, James; Kasteng, Frida; Vassall, Anna; Meek, Sylvia; Kirkwood, Betty

2015-04-12

If trained, equipped and utilised, community health workers (CHWs) delivering integrated community case management for sick children can potentially reduce child deaths by 60%. However, it is essential to maintain CHW motivation and performance. The inSCALE project aims to evaluate, using a cluster randomised controlled trial, the effect of interventions to increase CHW supervision and performance on the coverage of appropriate treatment for children with diarrhoea, pneumonia and malaria. Participatory methods were used to identify best practices and innovative solutions. Quantitative community based baseline surveys were conducted to allow restricted randomisation of clusters into intervention and control arms. Individual informed consent was obtained from all respondents. Following formative research and stakeholder consultations, two intervention packages were developed in Uganda and one in Mozambique. In Uganda, approximately 3,500 CHWs in 39 clusters were randomised into a mobile health (mHealth) arm, a participatory community engagement arm and a control arm. In Mozambique, 275 CHWs in 12 clusters were randomised into a mHealth arm and a control arm. The mHealth interventions encompass three components: 1) free phone communication between users; 2) data submission using phones with automated feedback, messages to supervisors for targeted supervision, and online data access for district statisticians; and 3) motivational messages. The community engagement arm in Uganda established village health clubs seeking to 1) improve the status and standing of CHWs, 2) increase demand for health services and 3) communicate that CHWs' work is important. Process evaluation was conducted after 10 months and end-line surveys will establish impact after 12 months in Uganda and 18 months in Mozambique. Main outcomes include proportion of sick children appropriately treated, CHW performance and motivation, and cost effectiveness of interventions. Study strengths include a user

Robust adaptive tracking control for nonholonomic mobile manipulator with uncertainties.

PubMed

Peng, Jinzhu; Yu, Jie; Wang, Jie

2014-07-01

In this paper, mobile manipulator is divided into two subsystems, that is, nonholonomic mobile platform subsystem and holonomic manipulator subsystem. First, the kinematic controller of the mobile platform is derived to obtain a desired velocity. Second, regarding the coupling between the two subsystems as disturbances, Lyapunov functions of the two subsystems are designed respectively. Third, a robust adaptive tracking controller is proposed to deal with the unknown upper bounds of parameter uncertainties and disturbances. According to the Lyapunov stability theory, the derived robust adaptive controller guarantees global stability of the closed-loop system, and the tracking errors and adaptive coefficient errors are all bounded. Finally, simulation results show that the proposed robust adaptive tracking controller for nonholonomic mobile manipulator is effective and has good tracking capacity. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Robust Nonlinear Feedback Control of Aircraft Propulsion Systems

NASA Technical Reports Server (NTRS)

Garrard, William L.; Balas, Gary J.; Litt, Jonathan (Technical Monitor)

2001-01-01

This is the final report on the research performed under NASA Glen grant NASA/NAG-3-1975 concerning feedback control of the Pratt & Whitney (PW) STF 952, a twin spool, mixed flow, after burning turbofan engine. The research focussed on the design of linear and gain-scheduled, multivariable inner-loop controllers for the PW turbofan engine using H-infinity and linear, parameter-varying (LPV) control techniques. The nonlinear turbofan engine simulation was provided by PW within the NASA Rocket Engine Transient Simulator (ROCETS) simulation software environment. ROCETS was used to generate linearized models of the turbofan engine for control design and analysis as well as the simulation environment to evaluate the performance and robustness of the controllers. Comparison between the H-infinity, and LPV controllers are made with the baseline multivariable controller and developed by Pratt & Whitney engineers included in the ROCETS simulation. Simulation results indicate that H-infinity and LPV techniques effectively achieve desired response characteristics with minimal cross coupling between commanded values and are very robust to unmodeled dynamics and sensor noise.

Physical activity for smoking cessation in pregnancy: randomised controlled trial.

PubMed

Ussher, Michael; Lewis, Sarah; Aveyard, Paul; Manyonda, Isaac; West, Robert; Lewis, Beth; Marcus, Bess; Riaz, Muhammad; Taylor, Adrian; Daley, Amanda; Coleman, Tim

2015-05-14

To determine the effectiveness of a physical activity intervention for smoking cessation during pregnancy. Parallel group, randomised controlled, multicentre trial. 13 hospitals in England, April 2009 to January 2014. 789 pregnant smokers, aged 16-50 years and at 10-24 weeks' gestation, who smoked at least one cigarette daily and were prepared to quit smoking one week after enrollment were randomised (1:1); 785 were included in the intention to treat analyses, with 392 assigned to the physical activity group. Interventions began one week before a target quit date. Participants were randomised to six weekly sessions of behavioural support for smoking cessation (control) or to this support plus 14 sessions combining supervised treadmill exercise and physical activity consultations. The primary outcome was continuous smoking abstinence from the target quit date until end of pregnancy, validated by exhaled carbon monoxide or salivary cotinine levels. To assess adherence, levels of moderate-vigorous intensity physical activity were self reported and in a 11.5% (n=90) random subsample of participants, physical activity was objectively measured by an accelerometer. No significant difference was found in rates of smoking abstinence at end of pregnancy between the physical activity and control groups (8% v 6%; odds ratio 1.21, 95% confidence interval 0.70 to 2.10). For the physical activity group compared with the control group, there was a 40% (95% confidence interval 13% to 73%), 34% (6% to 69%), and 46% (12% to 91%) greater increase in self reported minutes carrying out physical activity per week from baseline to one week, four weeks, and six weeks post-quit day, respectively. According to the accelerometer data there was no significant difference in physical activity levels between the groups. Participants attended a median of four treatment sessions in the intervention group and three in the control group. Adverse events and birth outcomes were similar between the two

An advanced robust method for speed control of switched reluctance motor

NASA Astrophysics Data System (ADS)

Zhang, Chao; Ming, Zhengfeng; Su, Zhanping; Cai, Zhuang

2018-05-01

This paper presents an advanced robust controller for the speed system of a switched reluctance motor (SRM) in the presence of nonlinearities, speed ripple, and external disturbances. It proposes that the adaptive fuzzy control is applied to regulate the motor speed in the outer loop, and the detector is used to obtain rotor detection in the inner loop. The new fuzzy logic tuning rules are achieved from the experience of the operator and the knowledge of the specialist. The fuzzy parameters are automatically adjusted online according to the error and its change of speed in the transient period. The designed detector can obtain the rotor's position accurately in each phase module. Furthermore, a series of contrastive simulations are completed between the proposed controller and proportion integration differentiation controller including low speed, medium speed, and high speed. Simulations show that the proposed robust controller enables the system reduced by at least 3% in overshoot, 6% in rise time, and 20% in setting time, respectively, and especially under external disturbances. Moreover, an actual SRM control system is constructed at 220 V 370 W. The experiment results further prove that the proposed robust controller has excellent dynamic performance and strong robustness.

Model reference tracking control of an aircraft: a robust adaptive approach

NASA Astrophysics Data System (ADS)

Tanyer, Ilker; Tatlicioglu, Enver; Zergeroglu, Erkan

2017-05-01

This work presents the design and the corresponding analysis of a nonlinear robust adaptive controller for model reference tracking of an aircraft that has parametric uncertainties in its system matrices and additive state- and/or time-dependent nonlinear disturbance-like terms in its dynamics. Specifically, robust integral of the sign of the error feedback term and an adaptive term is fused with a proportional integral controller. Lyapunov-based stability analysis techniques are utilised to prove global asymptotic convergence of the output tracking error. Extensive numerical simulations are presented to illustrate the performance of the proposed robust adaptive controller.

Adaptive integral robust control and application to electromechanical servo systems.

PubMed

Deng, Wenxiang; Yao, Jianyong

2017-03-01

This paper proposes a continuous adaptive integral robust control with robust integral of the sign of the error (RISE) feedback for a class of uncertain nonlinear systems, in which the RISE feedback gain is adapted online to ensure the robustness against disturbances without the prior bound knowledge of the additive disturbances. In addition, an adaptive compensation integrated with the proposed adaptive RISE feedback term is also constructed to further reduce design conservatism when the system also exists parametric uncertainties. Lyapunov analysis reveals the proposed controllers could guarantee the tracking errors are asymptotically converging to zero with continuous control efforts. To illustrate the high performance nature of the developed controllers, numerical simulations are provided. At the end, an application case of an actual electromechanical servo system driven by motor is also studied, with some specific design consideration, and comparative experimental results are obtained to verify the effectiveness of the proposed controllers. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Can a documentary increase help-seeking intentions in men? A randomised controlled trial

PubMed Central

Schlichthorst, Marisa; Spittal, Matthew J; Phelps, Andrea; Pirkis, Jane

2018-01-01

Background We investigated whether a public health intervention—a three-part documentary called Man Up which explored the relationship between masculinity and mental health, well-being and suicidality—could increase men’s intentions to seek help for personal and emotional problems. Methods We recruited men aged 18 years or over who were not at risk of suicide to participate in a double-blind randomised controlled trial. Participants were randomly assigned (1:1) via computer randomisation to view Man Up (the intervention) or a control documentary. We hypothesised that 4 weeks after viewing Man Up participants would report higher levels of intention to seek help than those who viewed the control documentary. Our primary outcome was assessed using the General Help Seeking Questionnaire, and was analysed for all participants. The trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12616001169437, Universal Trial Number: U1111-1186-1459) and was funded by the Movember Foundation. Results Three hundred and fifty-four men were assessed for eligibility for the trial and randomised to view Man Up or the control documentary. Of these, 337 completed all stages (nine participants were lost to follow-up in the intervention group and eight in the control group). Linear regression analysis showed a significant increase in intentions to seek help in the intervention group, but not in the control group (coef.=2.06, 95% CI 0.48 to 3.63, P=0.01). Conclusions Our trial demonstrates the potential for men’s health outcomes to be positively impacted by novel, media-based public health interventions that focus on traditional masculinity. Trial registration number ACTRN12616001169437, Results. PMID:29101215

Passivity-based Robust Control of Aerospace Systems

NASA Technical Reports Server (NTRS)

Kelkar, Atul G.; Joshi, Suresh M. (Technical Monitor)

2000-01-01

This report provides a brief summary of the research work performed over the duration of the cooperative research agreement between NASA Langley Research Center and Kansas State University. The cooperative agreement which was originally for the duration the three years was extended by another year through no-cost extension in order to accomplish the goals of the project. The main objective of the research was to develop passivity-based robust control methodology for passive and non-passive aerospace systems. The focus of the first-year's research was limited to the investigation of passivity-based methods for the robust control of Linear Time-Invariant (LTI) single-input single-output (SISO), open-loop stable, minimum-phase non-passive systems. The second year's focus was mainly on extending the passivity-based methodology to a larger class of non-passive LTI systems which includes unstable and nonminimum phase SISO systems. For LTI non-passive systems, five different passification. methods were developed. The primary effort during the years three and four was on the development of passification methodology for MIMO systems, development of methods for checking robustness of passification, and developing synthesis techniques for passifying compensators. For passive LTI systems optimal synthesis procedure was also developed for the design of constant-gain positive real controllers. For nonlinear passive systems, numerical optimization-based technique was developed for the synthesis of constant as well as time-varying gain positive-real controllers. The passivity-based control design methodology developed during the duration of this project was demonstrated by its application to various benchmark examples. These example systems included longitudinal model of an F-18 High Alpha Research Vehicle (HARV) for pitch axis control, NASA's supersonic transport wind tunnel model, ACC benchmark model, 1-D acoustic duct model, piezo-actuated flexible link model, and NASA

A randomised controlled trial of clinics in secondary schools for adolescents with asthma.

PubMed Central

Salisbury, Chris; Francis, Caia; Rogers, Chris; Parry, Kate; Thomas, Huw; Chadwick, Stephanie; Turton, Pat

2002-01-01

AIM: To compare a nurse-led clinic in schools versus care in general practice for adolescents with asthma. DESIGN OF STUDY: Randomised controlled trial in four schools; parallel observational study in two schools. SETTING: Six comprehensive schools. METHOD: In the randomised trial, pupils were invited to attend asthma review at a nurse-led clinic either in school, or in general practice. The parallel observational study compared pupils invited to practice care within and outside the randomised trial. Primary outcome measures were attendance for asthma review, symptom control, and quality of life. Secondary outcomes were knowledge, attitudes, inhaler technique, use of steroids, school absence, peak flow rate, preference for future care, health service utilisation, and costs. RESULTS: School clinic pupils were more likely to attend an asthma review than those randomised to practice care (90.8% versus 51.0% overall [P < 0.001, not consistent across schools]). No differences were observed in symptom control (P = 0.42) or quality of life (P = 0.63). Pupils attending school clinics had greater knowledge of asthma (difference = +0.38, 95% CI = 0.19 to 0.56), more positive attitudes (difference = +0.21, 95% CI = 0.05 to 0.36), and better inhaler technique (P < 0.001, not consistent across all schools). No differences were observed in school absence or peak flow rate. A majority (63%) of those who had received care at school preferred this model in future. Median costs of providing care at school and at the practice were 32.10 Pounds and 19.80 Pounds, respectively. No differences were observed between the groups in the observational comparison on any outcome. CONCLUSIONS: The schools asthma clinic increased uptake of asthma reviews. There were improvements in various process measures, but not in clinical outcomes. PMID:12528584

Robust control of flexible space vehicles with minimum structural excitation: On-off pulse control of flexible space vehicles

NASA Technical Reports Server (NTRS)

Wie, Bong; Liu, Qiang

1992-01-01

Both feedback and feedforward control approaches for uncertain dynamical systems (in particular, with uncertainty in structural mode frequency) are investigated. The control objective is to achieve a fast settling time (high performance) and robustness (insensitivity) to plant uncertainty. Preshaping of an ideal, time optimal control input using a tapped-delay filter is shown to provide a fast settling time with robust performance. A robust, non-minimum-phase feedback controller is synthesized with particular emphasis on its proper implementation for a non-zero set-point control problem. It is shown that a properly designed, feedback controller performs well, as compared with a time optimal open loop controller with special preshaping for performance robustness. Also included are two separate papers by the same authors on this subject.

Sliding-Mode Control Applied for Robust Control of a Highly Unstable Aircraft

NASA Technical Reports Server (NTRS)

Vetter, Travis Kenneth

2002-01-01

An investigation into the application of an observer based sliding mode controller for robust control of a highly unstable aircraft and methods of compensating for actuator dynamics is performed. After a brief overview of some reconfigurable controllers, sliding mode control (SMC) is selected because of its invariance properties and lack of need for parameter identification. SMC is reviewed and issues with parasitic dynamics, which cause system instability, are addressed. Utilizing sliding manifold boundary layers, the nonlinear control is converted to a linear control and sliding manifold design is performed in the frequency domain. An additional feedback form of model reference hedging is employed which is similar to a prefilter and has large benefits to system performance. The effects of inclusion of actuator dynamics into the designed plant is heavily investigated. Multiple Simulink models of the full longitudinal dynamics and wing deflection modes of the forward swept aero elastic vehicle (FSAV) are constructed. Additionally a linear state space models to analyze effects from various system parameters. The FSAV has a pole at +7 rad/sec and is non-minimum phase. The use of 'model actuators' in the feedback path, and varying there design, is heavily investigated for the resulting effects on plant robustness and tolerance to actuator failure. The use of redundant actuators is also explored and improved robustness is shown. All models are simulated with severe failure and excellent tracking, and task dependent handling qualities, and low pilot induced oscillation tendency is shown.

Low Bandwidth Robust Controllers for Flight

NASA Technical Reports Server (NTRS)

Biezad, Daniel J.; Chou, Hwei-Lan

1993-01-01

Through throttle manipulations, engine thrust can be used for emergency flight control for multi-engine aircraft. Previous study by NASA Dryden has shown the use of throttles for emergency flight control to be very difficult. In general, manual fly-by-throttle is extremely difficult - with landing almost impossible, but control augmentation makes runway landings feasible. Flight path control using throttles-only to achieve safe emergency landing for a large jet transport airplane, Boeing 720, was investigated using Quantitative Feedback Theory (QFT). Results were compared to an augmented control developed in a previous simulation study. The control augmentation corrected the unsatisfactory open-loop characteristics by increasing system bandwidth and damping, but increasing the control bandwidth substantially proved very difficult. The augmented pitch control is robust under no or moderate turbulence. The augmented roll control is sensitive to configuration changes.

Low bandwidth robust controllers for flight

NASA Technical Reports Server (NTRS)

Biezad, Daniel J.; Chou, Hwei-Lan

1993-01-01

Through throttle manipulations, engine thrust can be used for emergency flight control for multi-engine aircraft. Previous study by NASA Dryden has shown the use of throttles for emergency flight control to be very difficult. In general, manual fly-by-throttle is extremely difficult - with landing almost impossible, but control augmentation makes runway landings feasible. Flight path control using throttles-only to achieve safe emergency landing for a large jet transport airplane, Boeing 720, was investigated using Quantitative Feedback Theory (QFT). Results were compared to an augmented control developed in a previous simulation study. The control augmentation corrected the unsatisfactory open-loop characteristics by increasing system bandwidth and damping, but increasing the control bandwidth substantially proved very difficult. The augmented pitch control is robust under no or moderate turbulence. The augmented roll control is sensitive to configuration changes.

Analysis and interpretation of cost data in randomised controlled trials: review of published studies

PubMed Central

Barber, Julie A; Thompson, Simon G

1998-01-01

Objective To review critically the statistical methods used for health economic evaluations in randomised controlled trials where an estimate of cost is available for each patient in the study. Design Survey of published randomised trials including an economic evaluation with cost values suitable for statistical analysis; 45 such trials published in 1995 were identified from Medline. Main outcome measures The use of statistical methods for cost data was assessed in terms of the descriptive statistics reported, use of statistical inference, and whether the reported conclusions were justified. Results Although all 45 trials reviewed apparently had cost data for each patient, only 9 (20%) reported adequate measures of variability for these data and only 25 (56%) gave results of statistical tests or a measure of precision for the comparison of costs between the randomised groups. Only 16 (36%) of the articles gave conclusions which were justified on the basis of results presented in the paper. No paper reported sample size calculations for costs. Conclusions The analysis and interpretation of cost data from published trials reveal a lack of statistical awareness. Strong and potentially misleading conclusions about the relative costs of alternative therapies have often been reported in the absence of supporting statistical evidence. Improvements in the analysis and reporting of health economic assessments are urgently required. Health economic guidelines need to be revised to incorporate more detailed statistical advice. Key messagesHealth economic evaluations required for important healthcare policy decisions are often carried out in randomised controlled trialsA review of such published economic evaluations assessed whether statistical methods for cost outcomes have been appropriately used and interpretedFew publications presented adequate descriptive information for costs or performed appropriate statistical analysesIn at least two thirds of the papers, the main

The Basilar Artery International Cooperation Study (BASICS): study protocol for a randomised controlled trial

PubMed Central

2013-01-01

Background Despite recent advances in acute stroke treatment, basilar artery occlusion (BAO) is associated with a death or disability rate of close to 70%. Randomised trials have shown the safety and efficacy of intravenous thrombolysis (IVT) given within 4.5 h and have shown promising results of intra-arterial thrombolysis given within 6 h of symptom onset of acute ischaemic stroke, but these results do not directly apply to patients with an acute BAO because only few, if any, of these patients were included in randomised acute stroke trials. Recently the results of the Basilar Artery International Cooperation Study (BASICS), a prospective registry of patients with acute symptomatic BAO challenged the often-held assumption that intra-arterial treatment (IAT) is superior to IVT. Our observations in the BASICS registry underscore that we continue to lack a proven treatment modality for patients with an acute BAO and that current clinical practice varies widely. Design BASICS is a randomised controlled, multicentre, open label, phase III intervention trial with blinded outcome assessment, investigating the efficacy and safety of additional IAT after IVT in patients with BAO. The trial targets to include 750 patients, aged 18 to 85 years, with CT angiography or MR angiography confirmed BAO treated with IVT. Patients will be randomised between additional IAT followed by optimal medical care versus optimal medical care alone. IVT has to be initiated within 4.5 h from estimated time of BAO and IAT within 6 h. The primary outcome parameter will be favourable outcome at day 90 defined as a modified Rankin Scale score of 0–3. Discussion The BASICS registry was observational and has all the limitations of a non-randomised study. As the IAT approach becomes increasingly available and frequently utilised an adequately powered randomised controlled phase III trial investigating the added value of this therapy in patients with an acute symptomatic BAO is needed (clinicaltrials

Randomised controlled trial of site specific advice on school travel patterns.

PubMed

Rowland, D; DiGuiseppi, C; Gross, M; Afolabi, E; Roberts, I

2003-01-01

To evaluate the effect of site specific advice from a school travel coordinator on school travel patterns. Cluster randomised controlled trial of children attending 21 primary schools in the London boroughs of Camden and Islington. A post-intervention survey measured the proportion of children walking, cycling, or using public transport for travel to school, and the proportion of parents/carers very or quite worried about traffic and abduction. The proportion of schools that developed and implemented travel plans was assessed. One year post-intervention, nine of 11 intervention schools and none of 10 control schools had travel plans. Proportions of children walking, cycling, or using public transport on the school journey were similar in intervention and control schools. The proportion of parents who were very or quite worried about traffic danger was similar in the intervention (85%) and control groups (87%). However, after adjusting for baseline and other potential confounding factors we could not exclude the possibility of a modest reduction in parental concern about traffic danger as a result of the intervention. Having a school travel coordinator increased the production of school travel plans but there was no evidence that this changed travel patterns or reduced parental fears. Given the uncertainty about effectiveness, the policy of providing school travel coordinators should only be implemented within the context of a randomised controlled trial.

Kinematically Optimal Robust Control of Redundant Manipulators

NASA Astrophysics Data System (ADS)

Galicki, M.

2017-12-01

This work deals with the problem of the robust optimal task space trajectory tracking subject to finite-time convergence. Kinematic and dynamic equations of a redundant manipulator are assumed to be uncertain. Moreover, globally unbounded disturbances are allowed to act on the manipulator when tracking the trajectory by the endeffector. Furthermore, the movement is to be accomplished in such a way as to minimize both the manipulator torques and their oscillations thus eliminating the potential robot vibrations. Based on suitably defined task space non-singular terminal sliding vector variable and the Lyapunov stability theory, we derive a class of chattering-free robust kinematically optimal controllers, based on the estimation of transpose Jacobian, which seem to be effective in counteracting both uncertain kinematics and dynamics, unbounded disturbances and (possible) kinematic and/or algorithmic singularities met on the robot trajectory. The numerical simulations carried out for a redundant manipulator of a SCARA type consisting of the three revolute kinematic pairs and operating in a two-dimensional task space, illustrate performance of the proposed controllers as well as comparisons with other well known control schemes.

Linear, multivariable robust control with a mu perspective

NASA Technical Reports Server (NTRS)

Packard, Andy; Doyle, John; Balas, Gary

1993-01-01

The structured singular value is a linear algebra tool developed to study a particular class of matrix perturbation problems arising in robust feedback control of multivariable systems. These perturbations are called linear fractional, and are a natural way to model many types of uncertainty in linear systems, including state-space parameter uncertainty, multiplicative and additive unmodeled dynamics uncertainty, and coprime factor and gap metric uncertainty. The structured singular value theory provides a natural extension of classical SISO robustness measures and concepts to MIMO systems. The structured singular value analysis, coupled with approximate synthesis methods, make it possible to study the tradeoff between performance and uncertainty that occurs in all feedback systems. In MIMO systems, the complexity of the spatial interactions in the loop gains make it difficult to heuristically quantify the tradeoffs that must occur. This paper examines the role played by the structured singular value (and its computable bounds) in answering these questions, as well as its role in the general robust, multivariable control analysis and design problem.

Robust control of systems with real parameter uncertainty and unmodelled dynamics

NASA Technical Reports Server (NTRS)

Chang, Bor-Chin; Fischl, Robert

1991-01-01

During this research period we have made significant progress in the four proposed areas: (1) design of robust controllers via H infinity optimization; (2) design of robust controllers via mixed H2/H infinity optimization; (3) M-delta structure and robust stability analysis for structured uncertainties; and (4) a study on controllability and observability of perturbed plant. It is well known now that the two-Riccati-equation solution to the H infinity control problem can be used to characterize all possible stabilizing optimal or suboptimal H infinity controllers if the optimal H infinity norm or gamma, an upper bound of a suboptimal H infinity norm, is given. In this research, we discovered some useful properties of these H infinity Riccati solutions. Among them, the most prominent one is that the spectral radius of the product of these two Riccati solutions is a continuous, nonincreasing, convex function of gamma in the domain of interest. Based on these properties, quadratically convergent algorithms are developed to compute the optimal H infinity norm. We also set up a detailed procedure for applying the H infinity theory to robust control systems design. The desire to design controllers with H infinity robustness but H(exp 2) performance has recently resulted in mixed H(exp 2) and H infinity control problem formulation. The mixed H(exp 2)/H infinity problem have drawn the attention of many investigators. However, solution is only available for special cases of this problem. We formulated a relatively realistic control problem with H(exp 2) performance index and H infinity robustness constraint into a more general mixed H(exp 2)/H infinity problem. No optimal solution yet is available for this more general mixed H(exp 2)/H infinity problem. Although the optimal solution for this mixed H(exp 2)/H infinity control has not yet been found, we proposed a design approach which can be used through proper choice of the available design parameters to influence both

Maternal note-taking and infant care: a pilot randomised controlled trial.

PubMed

Kistin, Caroline J; Barrero-Castillero, Alejandra; Lewis, Sheilajane; Hoch, Rachel; Philipp, Barbara L; Bauchner, Howard; Wang, C Jason

2012-10-01

A pilot randomised controlled trial was conducted with postpartum mothers to assess the feasibility and impact of note-taking during newborn teaching. Controls received standard teaching; the intervention group received pen and paper to take notes. Subjects were called 2 days post-discharge to assess infant sleep position, breastfeeding, car seat use, satisfaction and information recall. 126 mothers were randomised. There was a consistent trend that intervention subjects were more likely to report infant supine sleep position (88% vs 78%, relative risks (RR) 1.13; 95% CI 0.95 to 1.34), breastfeeding (96% vs 86%, RR 1.11; 95% CI 0.99 to 1.25) and correct car seat use (98% vs 87%, RR 1.12; 95% CI 1.00 to 1.25). Satisfaction and information recall did not differ. Among first-time mothers, intervention subjects were significantly more likely to report infant supine sleep position (95% vs 65%, RR 1.46; 95% CI 1.06 to 2.00). Maternal note-taking is feasible and potentially efficacious in promoting desirable infant care.

Robust, Decoupled, Flight Control Design with Rate Saturating Actuators

NASA Technical Reports Server (NTRS)

Snell, S. A.; Hess, R. A.

1997-01-01

Techniques for the design of control systems for manually controlled, high-performance aircraft must provide the following: (1) multi-input, multi-output (MIMO) solutions, (2) acceptable handling qualities including no tendencies for pilot-induced oscillations, (3) a tractable approach for compensator design, (4) performance and stability robustness in the presence of significant plant uncertainty, and (5) performance and stability robustness in the presence actuator saturation (particularly rate saturation). A design technique built upon Quantitative Feedback Theory is offered as a candidate methodology which can provide flight control systems meeting these requirements, and do so over a considerable part of the flight envelope. An example utilizing a simplified model of a supermaneuverable fighter aircraft demonstrates the proposed design methodology.

Free breakfasts in schools: design and conduct of a cluster randomised controlled trial of the Primary School Free Breakfast Initiative in Wales [ISRCTN18336527

PubMed Central

Moore, Laurence; Moore, Graham F; Tapper, Katy; Lynch, Rebecca; Desousa, Carol; Hale, Janine; Roberts, Chris; Murphy, Simon

2007-01-01

Background School-based breakfast provision is increasingly being seen as a means of improving educational performance and dietary behaviour amongst children. Furthermore, recognition is growing that breakfast provision offers potential as a means of addressing social inequalities in these outcomes. At present however, the evidence base on the effectiveness of breakfast provision in bringing about these improvements is limited. Methods/Design This paper describes the research design of a large scale evaluation of the effectiveness of the Welsh Assembly Government's Primary School Free Breakfast Initiative. A cluster randomised trial, with school as the unit of randomisation was used for the outcome evaluation, with a nested qualitative process evaluation. Quantitative outcome measures included dietary habits, attitudes, cognitive function, classroom behaviour, and school attendance. The study recruited 111 primary schools in Wales, of which 56 were randomly assigned to control condition and 55 to intervention. Participants were Year 5 and 6 students (aged 9–11 years) in these schools. Data were collected for all 111 schools at each of three time points: baseline, 4 month and 12 month follow-up. This was achieved through a repeated cross-sectional survey of approximately 4350 students on each of these occasions. Of those students in Year 5 at baseline, 1975 provided data at one or both of the follow-ups, forming a nested cohort. The evaluation also included a nested process evaluation, using questionnaires, semi-structured interviews and case studies with students, school staff, and local authority scheme coordinators as key informants. Discussion An overview of the methods used for the evaluation is presented, providing an example of the feasibility of conducting robust evaluations of policy initiatives using a randomised trial design with nested process evaluation. Details are provided of response rates and the flow of participants. Reflection is offered on

Research in robust control for hypersonic aircraft

NASA Technical Reports Server (NTRS)

Calise, A. J.

1994-01-01

The research during the third reporting period focused on fixed order robust control design for hypersonic vehicles. A new technique was developed to synthesize fixed order H(sub infinity) controllers. A controller canonical form is imposed on the compensator structure and a homotopy algorithm is employed to perform the controller design. Various reduced order controllers are designed for a simplified version of the hypersonic vehicle model used in our previous studies to demonstrate the capabilities of the code. However, further work is needed to investigate the issue of numerical ill-conditioning for large order systems and to make the numerical approach more reliable.

Can a documentary increase help-seeking intentions in men? A randomised controlled trial.

PubMed

King, Kylie Elizabeth; Schlichthorst, Marisa; Spittal, Matthew J; Phelps, Andrea; Pirkis, Jane

2018-01-01

We investigated whether a public health intervention-a three-part documentary called Man Up which explored the relationship between masculinity and mental health, well-being and suicidality-could increase men's intentions to seek help for personal and emotional problems. We recruited men aged 18 years or over who were not at risk of suicide to participate in a double-blind randomised controlled trial. Participants were randomly assigned (1:1) via computer randomisation to view Man Up (the intervention) or a control documentary. We hypothesised that 4 weeks after viewing Man Up participants would report higher levels of intention to seek help than those who viewed the control documentary. Our primary outcome was assessed using the General Help Seeking Questionnaire, and was analysed for all participants. The trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12616001169437, Universal Trial Number: U1111-1186-1459) and was funded by the Movember Foundation. Three hundred and fifty-four men were assessed for eligibility for the trial and randomised to view Man Up or the control documentary. Of these, 337 completed all stages (nine participants were lost to follow-up in the intervention group and eight in the control group). Linear regression analysis showed a significant increase in intentions to seek help in the intervention group, but not in the control group (coef.=2.06, 95% CI 0.48 to 3.63, P=0.01). Our trial demonstrates the potential for men's health outcomes to be positively impacted by novel, media-based public health interventions that focus on traditional masculinity. ACTRN12616001169437, Results. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Debt Counselling for Depression in Primary Care: an adaptive randomised controlled pilot trial (DeCoDer study).

PubMed

Gabbay, Mark B; Ring, Adele; Byng, Richard; Anderson, Pippa; Taylor, Rod S; Matthews, Caryn; Harris, Tirril; Berry, Vashti; Byrne, Paula; Carter, Elliot; Clarke, Pam; Cocking, Laura; Edwards, Suzanne; Emsley, Richard; Fornasiero, Mauro; Frith, Lucy; Harris, Shaun; Huxley, Peter; Jones, Siw; Kinderman, Peter; King, Michael; Kosnes, Liv; Marshall, Daniel; Mercer, Dave; May, Carl; Nolan, Debbie; Phillips, Ceri; Rawcliffe, Tim; Sardani, Alexandra V; Shaw, Elizabeth; Thompson, Sam; Vickery, Jane; Wainman, Brian; Warner, Mark

2017-06-01

Depression and debt are common in the UK. Debt Counselling for Depression in Primary Care: an adaptive randomised controlled pilot trial (DeCoDer) aimed to assess the clinical effectiveness and cost-effectiveness of the addition of a primary care debt counselling advice service to usual care for patients with depression and debt. However, the study was terminated early during the internal pilot trial phase because of recruitment delays. This report describes the rationale, methods and findings of the pilot study, and implications for future research. The overarching aim of the internal pilot was to identify and resolve problems, thereby assessing the feasibility of the main trial. The specific objectives were to confirm methods for practice recruitment and the ability to recruit patients via the proposed approaches; to determine the acceptability of the study interventions and outcome measures; to assess contamination; to confirm the randomisation method for main trial and the level of participant attrition; and to check the robustness of data collection systems. An adaptive, parallel, two-group multicentre randomised controlled pilot trial with a nested mixed-methods process and economic evaluation. Both individual- and cluster (general practice)-level were was used in the pilot phase to assign participants to intervention or control groups. General practices in England and Wales. Individuals were included who were aged ≥ 18 years, scored ≥ 14 on the Beck Depression Inventory II and self-identified as having debt worries. The main exclusion criteria were being actively suicidal or psychotic and/or severely depressed and unresponsive to treatment; having a severe addiction to alcohol/illicit drugs; being unable/unwilling to give written informed consent; currently participating in other research including follow-up phases; having received Citizens Advice Bureau (CAB) debt advice in the past year; and not wanting debt advice via a general practice. The

Variable Neural Adaptive Robust Control: A Switched System Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lian, Jianming; Hu, Jianghai; Zak, Stanislaw H.

2015-05-01

Variable neural adaptive robust control strategies are proposed for the output tracking control of a class of multi-input multi-output uncertain systems. The controllers incorporate a variable-structure radial basis function (RBF) network as the self-organizing approximator for unknown system dynamics. The variable-structure RBF network solves the problem of structure determination associated with fixed-structure RBF networks. It can determine the network structure on-line dynamically by adding or removing radial basis functions according to the tracking performance. The structure variation is taken into account in the stability analysis of the closed-loop system using a switched system approach with the aid of the piecewisemore » quadratic Lyapunov function. The performance of the proposed variable neural adaptive robust controllers is illustrated with simulations.« less

Brief reminiscence activities improve state well-being and self-concept in young adults: a randomised controlled experiment.

PubMed

Hallford, David John; Mellor, David

2016-11-01

Reminiscence-based psychotherapies have been demonstrated to have robust effects on a range of therapeutic outcomes. However, little research has been conducted on the immediate effects of guided activities they are composed of, or how these might differ dependent on the type of reminiscence. The current study utilised a controlled experimental design, whereby 321 young adults (mean age = 25.5 years, SD = 3.0) were randomised to one of four conditions of online reminiscence activity: problem-solving (successful coping experiences), identity (self-defining events contributing to a meaningful and continuous personal identity), bitterness revival (negative or adverse events), or a control condition (any memory from their past). Participants recalled autobiographical memories congruent with the condition, and answered questions to facilitate reflection on the memories. The results indicated that problem-solving and identity reminiscence activities caused significant improvements in self-esteem, meaning in life, self-efficacy and affect, whereas no effects were found in the bitterness revival and control conditions. Problem-solving reminiscence also caused a small effect in increasing perceptions of a life narrative/s. Differences between the conditions did not appear to be explained by the positive-valence of memories. These results provide evidence for the specific effects of adaptive types of problem-solving and identity reminiscence in young adults.

A randomised controlled trial to assess the effectiveness of a nurse-led palliative care intervention for HIV positive patients on antiretroviral therapy: recruitment, refusal, randomisation and missing data.

PubMed

Lowther, Keira; Higginson, Irene J; Simms, Victoria; Gikaara, Nancy; Ahmed, Aabid; Ali, Zipporah; Afuande, Gaudencia; Kariuki, Hellen; Sherr, Lorraine; Jenkins, Rachel; Selman, Lucy; Harding, Richard

2014-09-03

Despite the life threatening nature of an HIV diagnosis and the multidimensional problems experienced by this patient population during antiretroviral therapy, the effectiveness of a palliative care approach for HIV positive patients on ART is as yet unknown. A randomised controlled trial (RCT) was conducted in a sample of 120 HIV positive patients on ART in an urban clinic in Mombasa, Kenya. The intervention was a minimum of seven sessions of multidimensional, person-centred care, given by HIV nurses trained in the palliative care approach over a period of 5 months. Rates of recruitment and refusal, the effectiveness of the randomisation procedure, trial follow-up and attrition and extent of missing data are reported.120 patients (60 randomised to control arm, 60 randomised to intervention arm) were recruited over 5.5 months, with a refusal rate of 55.7%. During the study period, three participants died from cancer, three withdrew (two moved away and one withdrew due to time constraints). All of these patients were in the intervention arm: details are reported. There were five additional missing monthly interviews in both the control and intervention study arm, bringing the total of missing data to 26 data points (4.3%). The quality and implications of these data are discussed extensively and openly, including the effect of full and ethical consent procedures, respondent burden, HIV stigma, accurate randomisation, patient safety and the impact of the intervention. Data on recruitment randomisation, attrition and missing data in clinical trials should be routinely reported, in conjunction with the now established practice of publishing study protocols to enhance research integrity, transparency and quality. Transparency is especially important in cross cultural settings, in which the sources of funding and trial design are often not based in the country of data collection. Findings reported can be used to inform future RCTs in this area. Clinicaltrials.gov NCT

Robust control of seismically excited cable stayed bridges with MR dampers

NASA Astrophysics Data System (ADS)

YeganehFallah, Arash; Khajeh Ahamd Attari, Nader

2017-03-01

In recent decades active and semi-active structural control are becoming attractive alternatives for enhancing performance of civil infrastructures subjected to seismic and winds loads. However, in order to have reliable active and semi-active control, there is a need to include information of uncertainties in design of the controller. In real world for civil structures, parameters such as loading places, stiffness, mass and damping are time variant and uncertain. These uncertainties in many cases model as parametric uncertainties. The motivation of this research is to design a robust controller for attenuating the vibrational responses of civil infrastructures, regarding their dynamical uncertainties. Uncertainties in structural dynamic’s parameters are modeled as affine uncertainties in state space modeling. These uncertainties are decoupled from the system through Linear Fractional Transformation (LFT) and are assumed to be unknown input to the system but norm bounded. The robust H ∞ controller is designed for the decoupled system to regulate the evaluation outputs and it is robust to effects of uncertainties, disturbance and sensors noise. The cable stayed bridge benchmark which is equipped with MR damper is considered for the numerical simulation. The simulated results show that the proposed robust controller can effectively mitigate undesired uncertainties effects on systems’ responds under seismic loading.

Robustness of a distributed neural network controller for locomotion in a hexapod robot

NASA Technical Reports Server (NTRS)

Chiel, Hillel J.; Beer, Randall D.; Quinn, Roger D.; Espenschied, Kenneth S.

1992-01-01

A distributed neural-network controller for locomotion, based on insect neurobiology, has been used to control a hexapod robot. How robust is this controller? Disabling any single sensor, effector, or central component did not prevent the robot from walking. Furthermore, statically stable gaits could be established using either sensor input or central connections. Thus, a complex interplay between central neural elements and sensor inputs is responsible for the robustness of the controller and its ability to generate a continuous range of gaits. These results suggest that biologically inspired neural-network controllers may be a robust method for robotic control.

Robust approximation-free prescribed performance control for nonlinear systems and its application

NASA Astrophysics Data System (ADS)

Sun, Ruisheng; Na, Jing; Zhu, Bin

2018-02-01

This paper presents a robust prescribed performance control approach and its application to nonlinear tail-controlled missile systems with unknown dynamics and uncertainties. The idea of prescribed performance function (PPF) is incorporated into the control design, such that both the steady-state and transient control performance can be strictly guaranteed. Unlike conventional PPF-based control methods, we further tailor a recently proposed systematic control design procedure (i.e. approximation-free control) using the transformed tracking error dynamics, which provides a proportional-like control action. Hence, the function approximators (e.g. neural networks, fuzzy systems) that are widely used to address the unknown nonlinearities in the nonlinear control designs are not needed. The proposed control design leads to a robust yet simplified function approximation-free control for nonlinear systems. The closed-loop system stability and the control error convergence are all rigorously proved. Finally, comparative simulations are conducted based on nonlinear missile systems to validate the improved response and the robustness of the proposed control method.

Inositol for prevention of neural tube defects: a pilot randomised controlled trial - CORRIGENDUM

PubMed Central

Greene, Nicholas D. E.; Leung, Kit-Yi; Gay, Victoria; Burren, Katie; Mills, Kevin; Chitty, Lyn S.; Copp, Andrew J.

2016-01-01

Although peri-conceptional folic acid (FA) supplementation can prevent a proportion of neural tube defects (NTDs), there is increasing evidence that many NTDs are FA non-responsive. The vitamin-like molecule inositol may offer a novel approach to preventing FA-non-responsive NTDs. Inositol prevented NTDs in a genetic mouse model, and was well tolerated by women in a small study of NTD recurrence. In the present study, we report the Prevention of Neural Tube Defects by Inositol (PONTI) pilot study designed to gain further experience of inositol usage in human pregnancy as a preliminary trial to a future large-scale controlled trial to evaluate efficacy of inositol in NTD prevention. Study subjects were UK women with a previous NTD pregnancy who planned to become pregnant again. Of 117 women who made contact, ninety-nine proved eligible and forty-seven agreed to be randomised (double-blind) to peri-conceptional supplementation with inositol plus FA or placebo plus FA. In total, thirty-three randomised pregnancies produced one NTD recurrence in the placebo plus FA group (n 19) and no recurrences in the inositol plus FA group (n 14). Of fifty-two women who declined randomisation, the peri-conceptional supplementation regimen and outcomes of twenty-four further pregnancies were documented. Two NTDs recurred, both in women who took only FA in their next pregnancy. No adverse pregnancy events were associated with inositol supplementation. The findings of the PONTI pilot study encourage a large-scale controlled trial of inositol for NTD prevention, but indicate the need for a careful study design in view of the unwillingness of many high-risk women to be randomised. PMID:26917444

Inositol for the prevention of neural tube defects: a pilot randomised controlled trial.

PubMed

Greene, Nicholas D E; Leung, Kit-Yi; Gay, Victoria; Burren, Katie; Mills, Kevin; Chitty, Lyn S; Copp, Andrew J

2016-03-28

Although peri-conceptional folic acid (FA) supplementation can prevent a proportion of neural tube defects (NTD), there is increasing evidence that many NTD are FA non-responsive. The vitamin-like molecule inositol may offer a novel approach to preventing FA-non-responsive NTD. Inositol prevented NTD in a genetic mouse model, and was well tolerated by women in a small study of NTD recurrence. In the present study, we report the Prevention of Neural Tube Defects by Inositol (PONTI) pilot study designed to gain further experience of inositol usage in human pregnancy as a preliminary trial to a future large-scale controlled trial to evaluate efficacy of inositol in NTD prevention. Study subjects were UK women with a previous NTD pregnancy who planned to become pregnant again. Of 117 women who made contact, ninety-nine proved eligible and forty-seven agreed to be randomised (double-blind) to peri-conceptional supplementation with inositol plus FA or placebo plus FA. In total, thirty-three randomised pregnancies produced one NTD recurrence in the placebo plus FA group (n 19) and no recurrences in the inositol plus FA group (n 14). Of fifty-two women who declined randomisation, the peri-conceptional supplementation regimen and outcomes of twenty-two further pregnancies were documented. Two NTD recurred, both in women who took only FA in their next pregnancy. No adverse pregnancy events were associated with inositol supplementation. The findings of the PONTI pilot study encourage a large-scale controlled trial of inositol for NTD prevention, but indicate the need for a careful study design in view of the unwillingness of many high-risk women to be randomised.

Skills Training to Avoid Inadvertent Plagiarism: Results from a Randomised Control Study

ERIC Educational Resources Information Center

Newton, Fiona J.; Wright, Jill D.; Newton, Joshua D.

2014-01-01

Plagiarism continues to be a concern within academic institutions. The current study utilised a randomised control trial of 137 new entry tertiary students to assess the efficacy of a scalable short training session on paraphrasing, patch writing and plagiarism. The results indicate that the training significantly enhanced students' overall…

Greening vacant lots to reduce violent crime: a randomised controlled trial

PubMed Central

Garvin, Eugenia C; Cannuscio, Carolyn C; Branas, Charles C

2014-01-01

Background Vacant lots are often overgrown with unwanted vegetation and filled with trash, making them attractive places to hide illegal guns, conduct illegal activities such as drug sales and prostitution, and engage in violent crime. There is some evidence that greening vacant lots is associated with reductions in violent crime. Methods We performed a randomised controlled trial of vacant lot greening to test the impact of this intervention on police reported crime and residents’ perceptions of safety and disorder. Greening consisted of cleaning the lots, planting grass and trees, and building a wooden fence around the perimeter. We randomly allocated two vacant lot clusters to the greening intervention or to the control status (no intervention). Administrative data were used to determine crime rates, and local resident interviews at baseline (n=29) and at follow-up (n=21) were used to assess perceptions of safety and disorder. Results Unadjusted difference-in-differences estimates showed a non-significant decrease in the number of total crimes and gun assaults around greened vacant lots compared with control. People around the intervention vacant lots reported feeling significantly safer after greening compared with those living around control vacant lots (p<0.01). Conclusions In this study, greening was associated with reductions in certain gun crimes and improvements in residents’ perceptions of safety. A larger randomised controlled trial is needed to further investigate the link between vacant lot greening and violence reduction. PMID:22871378

Physiotherapy Post Lumbar Discectomy: Prospective Feasibility and Pilot Randomised Controlled Trial

PubMed Central

Rushton, Alison; Goodwin, Peter C.

2015-01-01

Objectives To evaluate: acceptability and feasibility of trial procedures; distribution of scores on the Roland Morris Disability Questionnaire (RMDQ, planned primary outcome); and efficient working of trial components. Design and Setting A feasibility and external pilot randomised controlled trial (ISRCTN33808269, assigned 10/12/2012) was conducted across 2 UK secondary care outpatient physiotherapy departments associated with regional spinal surgery centres. Participants Consecutive consenting patients aged >18 years; post primary, single level, lumbar discectomy. Interventions Participants were randomised to either 1:1 physiotherapy outpatient management including patient leaflet, or patient leaflet alone. Main Outcome Measures Blinded assessments were made at 4 weeks post surgery (baseline) and 12 weeks post baseline (proposed primary end point). Secondary outcomes included: Global Perceived Effect, back/leg pain, straight leg raise, return to work/function, quality of life, fear avoidance, range of movement, medication, re-operation. Results At discharge, 110 (44%) eligible patients gave consent to be contacted. 59 (54%) patients were recruited. Loss to follow up was 39% at 12 weeks, with one site contributing 83% losses. Mean (SD) RMDQ was 10.07 (5.58) leaflet and 10.52 (5.94) physiotherapy/leaflet at baseline; and 5.37 (4.91) leaflet and 5.53 (4.49) physiotherapy/leaflet at 12 weeks. 5.1% zero scores at 12 weeks illustrated no floor effect. Sensitivity to change was assessed at 12 weeks with mean (SD) change -4.53 (6.41), 95%CI -7.61 to -1.44 for leaflet; and -6.18 (5.59), 95%CI -9.01 to -3.30 for physiotherapy/leaflet. RMDQ mean difference (95%CI) between change from baseline to twelve weeks was 1.65(-2.46 to 5.75). Mean difference (95%CI) between groups at 12 weeks was -0.16 (-3.36 to 3.04). Participant adherence with treatment was good. No adverse events were reported. Conclusions Both interventions were acceptable, and it is promising that they both

Robust control of a parallel hybrid drivetrain with a CVT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayer, T.; Schroeder, D.

1996-09-01

In this paper the design of a robust control system for a parallel hybrid drivetrain is presented. The drivetrain is based on a continuously variable transmission (CVT) and is therefore a highly nonlinear multiple-input-multiple-output system (MIMO-System). Input-Output-Linearization offers the possibility of linearizing and of decoupling the system. Since for example the vehicle mass varies with the load and the efficiency of the gearbox depends strongly on the actual working point, an exact linearization of the plant will mostly fail. Therefore a robust control algorithm based on sliding mode is used to control the drivetrain.

Enhanced robust fractional order proportional-plus-integral controller based on neural network for velocity control of permanent magnet synchronous motor.

PubMed

Zhang, Bitao; Pi, YouGuo

2013-07-01

The traditional integer order proportional-integral-differential (IO-PID) controller is sensitive to the parameter variation or/and external load disturbance of permanent magnet synchronous motor (PMSM). And the fractional order proportional-integral-differential (FO-PID) control scheme based on robustness tuning method is proposed to enhance the robustness. But the robustness focuses on the open-loop gain variation of controlled plant. In this paper, an enhanced robust fractional order proportional-plus-integral (ERFOPI) controller based on neural network is proposed. The control law of the ERFOPI controller is acted on a fractional order implement function (FOIF) of tracking error but not tracking error directly, which, according to theory analysis, can enhance the robust performance of system. Tuning rules and approaches, based on phase margin, crossover frequency specification and robustness rejecting gain variation, are introduced to obtain the parameters of ERFOPI controller. And the neural network algorithm is used to adjust the parameter of FOIF. Simulation and experimental results show that the method proposed in this paper not only achieve favorable tracking performance, but also is robust with regard to external load disturbance and parameter variation. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Control design for robust stability in linear regulators: Application to aerospace flight control

NASA Technical Reports Server (NTRS)

Yedavalli, R. K.

1986-01-01

Time domain stability robustness analysis and design for linear multivariable uncertain systems with bounded uncertainties is the central theme of the research. After reviewing the recently developed upper bounds on the linear elemental (structured), time varying perturbation of an asymptotically stable linear time invariant regulator, it is shown that it is possible to further improve these bounds by employing state transformations. Then introducing a quantitative measure called the stability robustness index, a state feedback conrol design algorithm is presented for a general linear regulator problem and then specialized to the case of modal systems as well as matched systems. The extension of the algorithm to stochastic systems with Kalman filter as the state estimator is presented. Finally an algorithm for robust dynamic compensator design is presented using Parameter Optimization (PO) procedure. Applications in a aircraft control and flexible structure control are presented along with a comparison with other existing methods.

Ethical considerations in placebo-controlled randomised clinical trials.

PubMed

Kaufman, Kenneth R

2015-06-01

Ethical considerations in standard medical care and clinical research are underpinnings to quality medicine. Similarly, the placebo-controlled double-blind randomised clinical trial is the gold standard for medical research and fundamental to the development of evidence-based medicine. Researchers and clinicians are challenged by ethical concerns in the informed consent with a need to maximise understanding and minimise therapeutic misconception. This editorial expands on themes raised by Chen et al 's article 'Disclosing the Potential Impact of Placebo Controls in Antidepressant Trials' and serves as an invitation for further submissions to BJPsych Open on ethics, research design and informed consent. None. © The Royal College of Psychiatrists 2015. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

Perineal massage in labour and prevention of perineal trauma: randomised controlled trial.

PubMed

Stamp, G; Kruzins, G; Crowther, C

2001-05-26

To determine the effects of perineal massage in the second stage of labour on perineal outcomes. Randomised controlled trial. At 36 weeks' gestation, women expecting normal birth of a singleton were asked to join the study. Women became eligible to be randomised in labour if they progressed to full dilatation of the cervix or 8 cm or more if nulliparous or 5 cm or more if multiparous. 1340 were randomised into the trial. Massage and stretching of the perineum during the second stage of labour with a water soluble lubricant. rates of intact perineum, episiotomies, and first, second, third, and fourth degree tears. pain at three and 10 days postpartum and pain, dyspareunia, resumption of sexual intercourse, and urinary and faecal incontinence and urgency three months postpartum. Rates of intact perineums, first and second degree tears, and episiotomies were similar in the massage and the control groups. There were fewer third degree tears in the massage group (12 (1.7%) v 23 (3.6%); absolute risk 2.11, relative risk 0.45; 95% confidence interval 0.23 to 0.93, P<0.04), though the trial was underpowered to measure this rarer outcome. Groups did not differ in any of the secondary outcomes at the three assessment points. The practice of perineal massage in labour does not increase the likelihood of an intact perineum or reduce the risk of pain, dyspareunia, or urinary and faecal problems.

Robust quantum control using smooth pulses and topological winding

NASA Astrophysics Data System (ADS)

Barnes, Edwin; Wang, Xin

2015-03-01

Perhaps the greatest challenge in achieving control of microscopic quantum systems is the decoherence induced by the environment, a problem which pervades experimental quantum physics and is particularly severe in the context of solid state quantum computing and nanoscale quantum devices because of the inherently strong coupling to the surrounding material. We present an analytical approach to constructing intrinsically robust driving fields which automatically cancel the leading-order noise-induced errors in a qubit's evolution exactly. We address two of the most common types of non-Markovian noise that arise in qubits: slow fluctuations of the qubit energy splitting and fluctuations in the driving field itself. We demonstrate our method by constructing robust quantum gates for several types of spin qubits, including phosphorous donors in silicon and nitrogen-vacancy centers in diamond. Our results constitute an important step toward achieving robust generic control of quantum systems, bringing their novel applications closer to realization. Work supported by LPS-CMTC.

Robust fault-tolerant tracking control design for spacecraft under control input saturation.

PubMed

Bustan, Danyal; Pariz, Naser; Sani, Seyyed Kamal Hosseini

2014-07-01

In this paper, a continuous globally stable tracking control algorithm is proposed for a spacecraft in the presence of unknown actuator failure, control input saturation, uncertainty in inertial matrix and external disturbances. The design method is based on variable structure control and has the following properties: (1) fast and accurate response in the presence of bounded disturbances; (2) robust to the partial loss of actuator effectiveness; (3) explicit consideration of control input saturation; and (4) robust to uncertainty in inertial matrix. In contrast to traditional fault-tolerant control methods, the proposed controller does not require knowledge of the actuator faults and is implemented without explicit fault detection and isolation processes. In the proposed controller a single parameter is adjusted dynamically in such a way that it is possible to prove that both attitude and angular velocity errors will tend to zero asymptotically. The stability proof is based on a Lyapunov analysis and the properties of the singularity free quaternion representation of spacecraft dynamics. Results of numerical simulations state that the proposed controller is successful in achieving high attitude performance in the presence of external disturbances, actuator failures, and control input saturation. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Robustness of Thirty Meter Telescope primary mirror control

NASA Astrophysics Data System (ADS)

Macmynowski, Douglas G.; Thompson, Peter M.; Shelton, Chris; Roberts, Lewis C., Jr.

2010-07-01

The primary mirror control system for the Thirty Meter Telescope (TMT) maintains the alignment of the 492 segments in the presence of both quasi-static (gravity and thermal) and dynamic disturbances due to unsteady wind loads. The latter results in a desired control bandwidth of 1Hz at high spatial frequencies. The achievable bandwidth is limited by robustness to (i) uncertain telescope structural dynamics (control-structure interaction) and (ii) small perturbations in the ill-conditioned influence matrix that relates segment edge sensor response to actuator commands. Both of these effects are considered herein using models of TMT. The former is explored through multivariable sensitivity analysis on a reduced-order Zernike-basis representation of the structural dynamics. The interaction matrix ("A-matrix") uncertainty has been analyzed theoretically elsewhere, and is examined here for realistic amplitude perturbations due to segment and sensor installation errors, and gravity and thermal induced segment motion. The primary influence of A-matrix uncertainty is on the control of "focusmode"; this is the least observable mode, measurable only through the edge-sensor (gap-dependent) sensitivity to the dihedral angle between segments. Accurately estimating focus-mode will require updating the A-matrix as a function of the measured gap. A-matrix uncertainty also results in a higher gain-margin requirement for focus-mode, and hence the A-matrix and CSI robustness need to be understood simultaneously. Based on the robustness analysis, the desired 1 Hz bandwidth is achievable in the presence of uncertainty for all except the lowest spatial-frequency response patterns of the primary mirror.

Robust multi-model control of an autonomous wind power system

NASA Astrophysics Data System (ADS)

Cutululis, Nicolas Antonio; Ceanga, Emil; Hansen, Anca Daniela; Sørensen, Poul

2006-09-01

This article presents a robust multi-model control structure for a wind power system that uses a variable speed wind turbine (VSWT) driving a permanent magnet synchronous generator (PMSG) connected to a local grid. The control problem consists in maximizing the energy captured from the wind for varying wind speeds. The VSWT-PMSG linearized model analysis reveals the resonant nature of its dynamic at points on the optimal regimes characteristic (ORC). The natural frequency of the system and the damping factor are strongly dependent on the operating point on the ORC. Under these circumstances a robust multi-model control structure is designed. The simulation results prove the viability of the proposed control structure. Copyright

Computational methods of robust controller design for aerodynamic flutter suppression

NASA Technical Reports Server (NTRS)

Anderson, L. R.

1981-01-01

The development of Riccati iteration, a tool for the design and analysis of linear control systems is examined. First, Riccati iteration is applied to the problem of pole placement and order reduction in two-time scale control systems. Order reduction, yielding a good approximation to the original system, is demonstrated using a 16th order linear model of a turbofan engine. Next, a numerical method for solving the Riccati equation is presented and demonstrated for a set of eighth order random examples. A literature review of robust controller design methods follows which includes a number of methods for reducing the trajectory and performance index sensitivity in linear regulators. Lastly, robust controller design for large parameter variations is discussed.

Osteopathic manipulative treatment and pain in preterms: study protocol for a randomised controlled trial.

PubMed

Cerritelli, Francesco; Cicchitti, Luca; Martelli, Marta; Barlafante, Gina; Renzetti, Cinzia; Pizzolorusso, Gianfranco; Lupacchini, Mariacristina; D'Orazio, Marianna; Marinelli, Benedetta; Cozzolino, Vincenzo; Fusilli, Paola; D'Incecco, Carmine

2015-03-08

Recent evidence proved the necessity to improve health care and pain management in newborns. Osteopathic manipulative treatment (OMT) has been largely used to treat painful syndromes as well as term and preterm newborns. Recent studies have demonstrated positive results of osteopathy in reducing length of stay and costs. However, no trials were carried out on pain in newborns. The aim of the present clinical trial is to explore the effectiveness of osteopathic treatment in reducing pain in a sample of preterms. A three-armed single blinded placebo-control randomised controlled trial protocol has been designed to primarily evaluate the extent to which OMT is effective in reducing pain in preterms. One hundred and twenty newborns will be enrolled from one tertiary neonatal intensive care unit in central Italy and randomised in three groups: study, sham and control. The study group will be further prospectively randomised in two subgroups: experienced osteopaths and students. All preterms will receive standard medical care. Osteopathic treatment will be applied to the study group only whilst 'soft touch' will be administer to the sham group only. Newborns will undergo manual sessions once a week for the entire period of hospitalisation. Blinding will be assured for neonatal staff and outcome assessor. Primary outcome will be the mean difference in baseline score changes of PIPP questionnaire between discharge and entry among the three groups. Secondary outcomes will be: mean difference in length of stay and costs between groups. Statistical analyses will use per-protocol analysis method. Missing data will be handled using last observation carried forward imputation technique. The present single blinded randomised controlled trial has been designed to explore potential advantages of OMT in the management of newborns' pain. Currently, based on a patient-centred need-based approach, this research will be looking at the benefit of osteopathic care rather than the efficacy

Nonlinear robust control of hypersonic aircrafts with interactions between flight dynamics and propulsion systems.

PubMed

Li, Zhaoying; Zhou, Wenjie; Liu, Hao

2016-09-01

This paper addresses the nonlinear robust tracking controller design problem for hypersonic vehicles. This problem is challenging due to strong coupling between the aerodynamics and the propulsion system, and the uncertainties involved in the vehicle dynamics including parametric uncertainties, unmodeled model uncertainties, and external disturbances. By utilizing the feedback linearization technique, a linear tracking error system is established with prescribed references. For the linear model, a robust controller is proposed based on the signal compensation theory to guarantee that the tracking error dynamics is robustly stable. Numerical simulation results are given to show the advantages of the proposed nonlinear robust control method, compared to the robust loop-shaping control approach. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Inherent robustness of discrete-time adaptive control systems

NASA Technical Reports Server (NTRS)

Ma, C. C. H.

1986-01-01

Global stability robustness with respect to unmodeled dynamics, arbitrary bounded internal noise, as well as external disturbance is shown to exist for a class of discrete-time adaptive control systems when the regressor vectors of these systems are persistently exciting. Although fast adaptation is definitely undesirable, so far as attaining the greatest amount of global stability robustness is concerned, slow adaptation is shown to be not necessarily beneficial. The entire analysis in this paper holds for systems with slowly varying return difference matrices; the plants in these systems need not be slowly varying.

Designing for Damage: Robust Flight Control Design using Sliding Mode Techniques

NASA Technical Reports Server (NTRS)

Vetter, T. K.; Wells, S. R.; Hess, Ronald A.; Bacon, Barton (Technical Monitor); Davidson, John (Technical Monitor)

2002-01-01

A brief review of sliding model control is undertaken, with particular emphasis upon the effects of neglected parasitic dynamics. Sliding model control design is interpreted in the frequency domain. The inclusion of asymptotic observers and control 'hedging' is shown to reduce the effects of neglected parasitic dynamics. An investigation into the application of observer-based sliding mode control to the robust longitudinal control of a highly unstable is described. The sliding mode controller is shown to exhibit stability and performance robustness superior to that of a classical loop-shaped design when significant changes in vehicle and actuator dynamics are employed to model airframe damage.

Distributed robust adaptive control of high order nonlinear multi agent systems.

PubMed

Hashemi, Mahnaz; Shahgholian, Ghazanfar

2018-03-01

In this paper, a robust adaptive neural network based controller is presented for multi agent high order nonlinear systems with unknown nonlinear functions, unknown control gains and unknown actuator failures. At first, Neural Network (NN) is used to approximate the nonlinear uncertainty terms derived from the controller design procedure for the followers. Then, a novel distributed robust adaptive controller is developed by combining the backstepping method and the Dynamic Surface Control (DSC) approach. The proposed controllers are distributed in the sense that the designed controller for each follower agent only requires relative state information between itself and its neighbors. By using the Young's inequality, only few parameters need to be tuned regardless of NN nodes number. Accordingly, the problems of dimensionality curse and explosion of complexity are counteracted, simultaneously. New adaptive laws are designed by choosing the appropriate Lyapunov-Krasovskii functionals. The proposed approach proves the boundedness of all the closed-loop signals in addition to the convergence of the distributed tracking errors to a small neighborhood of the origin. Simulation results indicate that the proposed controller is effective and robust. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Robust levitation control for maglev systems with guaranteed bounded airgap.

PubMed

Xu, Jinquan; Chen, Ye-Hwa; Guo, Hong

2015-11-01

The robust control design problem for the levitation control of a nonlinear uncertain maglev system is considered. The uncertainty is (possibly) fast time-varying. The system has magnitude limitation on the airgap between the suspended chassis and the guideway in order to prevent undesirable contact. Furthermore, the (global) matching condition is not satisfied. After a three-step state transformation, a robust control scheme for the maglev vehicle is proposed, which is able to guarantee the uniform boundedness and uniform ultimate boundedness of the system, regardless of the uncertainty. The magnitude limitation of the airgap is guaranteed, regardless of the uncertainty. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Robust distributed model predictive control of linear systems with structured time-varying uncertainties

NASA Astrophysics Data System (ADS)

Zhang, Langwen; Xie, Wei; Wang, Jingcheng

2017-11-01

In this work, synthesis of robust distributed model predictive control (MPC) is presented for a class of linear systems subject to structured time-varying uncertainties. By decomposing a global system into smaller dimensional subsystems, a set of distributed MPC controllers, instead of a centralised controller, are designed. To ensure the robust stability of the closed-loop system with respect to model uncertainties, distributed state feedback laws are obtained by solving a min-max optimisation problem. The design of robust distributed MPC is then transformed into solving a minimisation optimisation problem with linear matrix inequality constraints. An iterative online algorithm with adjustable maximum iteration is proposed to coordinate the distributed controllers to achieve a global performance. The simulation results show the effectiveness of the proposed robust distributed MPC algorithm.

Quantity, topics, methods and findings of randomised controlled trials published by German university departments of general practice - systematic review.

PubMed

Heinmüller, Stefan; Schneider, Antonius; Linde, Klaus

2016-04-23

Academic infrastructures and networks for clinical research in primary care receive little funding in Germany. We aimed to provide an overview of the quantity, topics, methods and findings of randomised controlled trials published by German university departments of general practice. We searched Scopus (last search done in April 2015), publication lists of institutes and references of included articles. We included randomised trials published between January 2000 and December 2014 with a first or last author affiliated with a German university department of general practice or family medicine. Risk of bias was assessed with the Cochrane tool, and study findings were quantified using standardised mean differences (SMDs). Thirty-three trials met the inclusion criteria. Seventeen were cluster-randomised trials, with a majority investigating interventions aimed at improving processes compared with usual care. Sample sizes varied between 6 and 606 clusters and 168 and 7807 participants. The most frequent methodological problem was risk of selection bias due to recruitment of individuals after randomisation of clusters. Effects of interventions over usual care were mostly small (SMD <0.3). Sixteen trials randomising individual participants addressed a variety of treatment and educational interventions. Sample sizes varied between 20 and 1620 participants. The methodological quality of the trials was highly variable. Again, effects of experimental interventions over controls were mostly small. Despite limited funding, German university institutes of general practice or family medicine are increasingly performing randomised trials. Cluster-randomised trials on practice improvement are a focus, but problems with allocation concealment are frequent.

Art participation for psychosocial wellbeing during stroke rehabilitation: a feasibility randomised controlled trial.

PubMed

Morris, Jacqui H; Kelly, Chris; Joice, Sara; Kroll, Thilo; Mead, Gillian; Donnan, Peter; Toma, Madalina; Williams, Brian

2017-08-30

To examine the feasibility of undertaking a pragmatic single-blind randomised controlled trial (RCT) of a visual arts participation programme to evaluate effects on survivor wellbeing within stroke rehabilitation. Stroke survivors receiving in-patient rehabilitation were randomised to receive eight art participation sessions (n = 41) or usual care (n = 40). Recruitment, retention, preference for art participation and change in selected outcomes were evaluated at end of intervention outcome assessment and three-month follow-up. Of 315 potentially eligible participants 81 (29%) were recruited. 88% (n = 71) completed outcome and 77% (n = 62) follow-up assessments. Of eight intervention group non-completers, six had no preference for art participation. Outcome completion varied between 97% and 77%. Running groups was difficult because of randomisation timing. Effectiveness cannot be determined from this feasibility study but effects sizes suggested art participation may benefit emotional wellbeing, measured on the positive and negative affect schedule, and self-efficacy for Art (d = 0.24-0.42). Undertaking a RCT of art participation within stroke rehabilitation was feasible. Art participation may enhance self-efficacy and positively influence emotional wellbeing. These should be outcomes in a future definitive trial. A cluster RCT would ensure art groups could be reliably convened. Fewer measures, and better retention strategies are required. Implications for Rehabilitation This feasibility randomised controlled trial (RCT) showed that recruiting and retaining stroke survivors in an RCT of a visual arts participation intervention within stroke rehabilitation was feasible. Preference to participate in art activities may influence recruitment and drop-out rates, and should be addressed and evaluated fully. Art participation as part of rehabilitation may improve some aspects of post-stroke wellbeing, including positive affect and self-efficacy for art

Targeted full energy and protein delivery in critically ill patients: a study protocol for a pilot randomised control trial (FEED Trial).

PubMed

Fetterplace, Kate; Deane, Adam M; Tierney, Audrey; Beach, Lisa; Knight, Laura D; Rechnitzer, Thomas; Forsyth, Adrienne; Mourtzakis, Marina; Presneill, Jeffrey; MacIsaac, Christopher

2018-01-01

Current guidelines for the provision of protein for critically ill patients are based on incomplete evidence, due to limited data from randomised controlled trials. The present pilot randomised controlled trial is part of a program of work to expand knowledge about the clinical effects of protein delivery to critically ill patients. The primary aim of this pilot study is to determine whether an enteral feeding protocol using a volume target, with additional protein supplementation, delivers a greater amount of protein and energy to mechanically ventilated critically ill patients than a standard nutrition protocol. The secondary aims are to evaluate the potential effects of this feeding strategy on muscle mass and other patient-centred outcomes. This prospective, single-centred, pilot, randomised control trial will include 60 participants who are mechanically ventilated and can be enterally fed. Following informed consent, the participants receiving enteral nutrition in the intensive care unit (ICU) will be allocated using a randomisation algorithm in a 1:1 ratio to the intervention (high-protein daily volume-based feeding protocol, providing 25 kcal/kg and 1.5 g/kg protein) or standard care (hourly rate-based feeding protocol providing 25 kcal/kg and 1 g/kg protein). The co-primary outcomes are the average daily protein and energy delivered to the end of day 15 following randomisation. The secondary outcomes include change in quadriceps muscle layer thickness (QMLT) from baseline (prior to randomisation) to ICU discharge and other nutritional and patient-centred outcomes. This trial aims to examine whether a volume-based feeding protocol with supplemental protein increases protein and energy delivery. The potential effect of such increases on muscle mass loss will be explored. These outcomes will assist in formulating larger randomised control trials to assess mortality and morbidity. Australian New Zealand Clinical Trials Registry (ANZCTR

Robust H∞ output-feedback control for path following of autonomous ground vehicles

NASA Astrophysics Data System (ADS)

Hu, Chuan; Jing, Hui; Wang, Rongrong; Yan, Fengjun; Chadli, Mohammed

2016-03-01

This paper presents a robust H∞ output-feedback control strategy for the path following of autonomous ground vehicles (AGVs). Considering the vehicle lateral velocity is usually hard to measure with low cost sensor, a robust H∞ static output-feedback controller based on the mixed genetic algorithms (GA)/linear matrix inequality (LMI) approach is proposed to realize the path following without the information of the lateral velocity. The proposed controller is robust to the parametric uncertainties and external disturbances, with the parameters including the tire cornering stiffness, vehicle longitudinal velocity, yaw rate and road curvature. Simulation results based on CarSim-Simulink joint platform using a high-fidelity and full-car model have verified the effectiveness of the proposed control approach.

Robust Gain-Scheduled Fault Tolerant Control for a Transport Aircraft

NASA Technical Reports Server (NTRS)

Shin, Jong-Yeob; Gregory, Irene

2007-01-01

This paper presents an application of robust gain-scheduled control concepts using a linear parameter-varying (LPV) control synthesis method to design fault tolerant controllers for a civil transport aircraft. To apply the robust LPV control synthesis method, the nonlinear dynamics must be represented by an LPV model, which is developed using the function substitution method over the entire flight envelope. The developed LPV model associated with the aerodynamic coefficient uncertainties represents nonlinear dynamics including those outside the equilibrium manifold. Passive and active fault tolerant controllers (FTC) are designed for the longitudinal dynamics of the Boeing 747-100/200 aircraft in the presence of elevator failure. Both FTC laws are evaluated in the full nonlinear aircraft simulation in the presence of the elevator fault and the results are compared to show pros and cons of each control law.

The NAtional randomised controlled Trial of Tonsillectomy IN Adults (NATTINA): a clinical and cost-effectiveness study: study protocol for a randomised control trial.

PubMed

Rubie, Isabel; Haighton, Catherine; O'Hara, James; Rousseau, Nikki; Steen, Nick; Stocken, Deborah D; Sullivan, Frank; Vale, Luke; Wilkes, Scott; Wilson, Janet

2015-06-06

The role of tonsillectomy in the management of adult tonsillitis remains uncertain and UK regional variation in tonsillectomy rates persists. Patients, doctors and health policy makers wish to know the costs and benefits of tonsillectomy against conservative management and whether therapy can be better targeted to maximise benefits and minimise risks of surgery, hence maximising cost-effective use of resources. NATTINA incorporates the first attempt to map current NHS referral criteria against other metrics of tonsil disease severity. A UK multi-centre, randomised, controlled trial for adults with recurrent tonsillitis to compare the clinical and cost-effectiveness of tonsillectomy versus conservative management. An initial feasibility study comprises qualitative interviews to investigate the practicality of the protocol, including willingness to randomise and be randomised. Approximately 20 otolaryngology staff, 10 GPs and 15 ENT patients will be recruited over 5 months in all 9 proposed main trial participating sites. A 6-month internal pilot will then recruit 72 patients across 6 of the 9 sites. Participants will be adults with recurrent acute tonsillitis referred by a GP to secondary care. Randomisation between tonsillectomy and conservative management will be according to a blocked allocation method in a 1:1 ratio stratified by centre and baseline disease severity. If the pilot is successful, the main trial will recruit a further 528 patients over 18 months in all 9 participating sites. All participants will be followed up for a total of 24 months, throughout which both primary and secondary outcome data will be collected. The primary outcome is the number of sore throat days experienced over the 24-month follow-up. The pilot and main trials include an embedded qualitative process evaluation. NATTINA is designed to evaluate the relative effectiveness and efficiency of tonsillectomy versus conservative management in patients with recurrent sore throat who are

Randomised controlled trials of homeopathy in humans: characterising the research journal literature for systematic review.

PubMed

Mathie, Robert T; Hacke, Daniela; Clausen, Jürgen; Nicolai, Ton; Riley, David S; Fisher, Peter

2013-01-01

A new programme of systematic reviews of randomised controlled trials (RCTs) in homeopathy will distinguish important attributes of RCT records, including: placebo controlled versus other-than-placebo (OTP) controlled; individualised versus non-individualised homeopathy; peer-reviewed (PR) versus non peer-reviewed (NPR) sources. (a) To outline the methods used to search and categorise the RCT literature; (b) to report details of the records retrieved; (c) to compare our retrieved records with those reported in two previous systematic reviews (Linde et al., 1997; Shang et al., 2005). Ten major electronic databases were searched for records published up to the end of 2011. A record was accepted for subsequent systematic review if it was a substantive report of a clinical trial of homeopathic treatment or prophylaxis in humans, randomised and controlled, and published in a PR or NPR journal. 489 records were potentially eligible: 226 were rejected as non-journal, minor or repeat publications, or lacking randomisation and/or controls and/or a 'homeopathic' intervention; 263 (164 PR, 99 NPR) were acceptable for systematic review. The 263 accepted records comprised 217 (137 PR, 80 NPR) placebo-controlled RCTs, of which 121 were included by, 66 were published after, and 30 were potentially eligible for, but not listed by, Linde or Shang. The 137 PR records of placebo-controlled RCTs comprise 41 on individualised homeopathy and 96 on non-individualised homeopathy. Our findings clarify the RCT literature in homeopathy. The 263 accepted journal papers will be the basis for our forthcoming programme of systematic reviews. Copyright © 2012 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.

Evaluation of the effect of patient education on rates of falls in older hospital patients: Description of a randomised controlled trial

PubMed Central

Hill, Anne-Marie; Hill, Keith; Brauer, Sandra; Oliver, David; Hoffmann, Tammy; Beer, Christopher; McPhail, Steven; Haines, Terry P

2009-01-01

Background Accidental falls by older patients in hospital are one of the most commonly reported adverse events. Falls after discharge are also common. These falls have enormous physical, psychological and social consequences for older patients, including serious physical injury and reduced quality of life, and are also a source of substantial cost to health systems worldwide. There have been a limited number of randomised controlled trials, mainly using multifactorial interventions, aiming to prevent older people falling whilst inpatients. Trials to date have produced conflicting results and recent meta-analyses highlight that there is still insufficient evidence to clearly identify which interventions may reduce the rate of falls, and falls related injuries, in this population. Methods and design A prospective randomised controlled trial (n = 1206) is being conducted at two hospitals in Australia. Patients are eligible to be included in the trial if they are over 60 years of age and they, or their family or guardian, give written consent. Participants are randomised into three groups. The control group continues to receive usual care. Both intervention groups receive a specifically designed patient education intervention on minimising falls in addition to usual care. The education is delivered by Digital Video Disc (DVD) and written workbook and aims to promote falls prevention activities by participants. One of the intervention groups also receives follow up education training visits by a health professional. Blinded assessors conduct baseline and discharge assessments and follow up participants for 6 months after discharge. The primary outcome measure is falls by participants in hospital. Secondary outcome measures include falls at home after discharge, knowledge of falls prevention strategies and motivation to engage in falls prevention activities after discharge. All analyses will be based on intention to treat principle. Discussion This trial will examine the

Adaptive GSA-based optimal tuning of PI controlled servo systems with reduced process parametric sensitivity, robust stability and controller robustness.

PubMed

Precup, Radu-Emil; David, Radu-Codrut; Petriu, Emil M; Radac, Mircea-Bogdan; Preitl, Stefan

2014-11-01

This paper suggests a new generation of optimal PI controllers for a class of servo systems characterized by saturation and dead zone static nonlinearities and second-order models with an integral component. The objective functions are expressed as the integral of time multiplied by absolute error plus the weighted sum of the integrals of output sensitivity functions of the state sensitivity models with respect to two process parametric variations. The PI controller tuning conditions applied to a simplified linear process model involve a single design parameter specific to the extended symmetrical optimum (ESO) method which offers the desired tradeoff to several control system performance indices. An original back-calculation and tracking anti-windup scheme is proposed in order to prevent the integrator wind-up and to compensate for the dead zone nonlinearity of the process. The minimization of the objective functions is carried out in the framework of optimization problems with inequality constraints which guarantee the robust stability with respect to the process parametric variations and the controller robustness. An adaptive gravitational search algorithm (GSA) solves the optimization problems focused on the optimal tuning of the design parameter specific to the ESO method and of the anti-windup tracking gain. A tuning method for PI controllers is proposed as an efficient approach to the design of resilient control systems. The tuning method and the PI controllers are experimentally validated by the adaptive GSA-based tuning of PI controllers for the angular position control of a laboratory servo system.

Robust Control Design via Linear Programming

NASA Technical Reports Server (NTRS)

Keel, L. H.; Bhattacharyya, S. P.

1998-01-01

This paper deals with the problem of synthesizing or designing a feedback controller of fixed dynamic order. The closed loop specifications considered here are given in terms of a target performance vector representing a desired set of closed loop transfer functions connecting various signals. In general these point targets are unattainable with a fixed order controller. By enlarging the target from a fixed point set to an interval set the solvability conditions with a fixed order controller are relaxed and a solution is more easily enabled. Results from the parametric robust control literature can be used to design the interval target family so that the performance deterioration is acceptable, even when plant uncertainty is present. It is shown that it is possible to devise a computationally simple linear programming approach that attempts to meet the desired closed loop specifications.

Intelligent robust control for uncertain nonlinear time-varying systems and its application to robotic systems.

PubMed

Chang, Yeong-Chan

2005-12-01

This paper addresses the problem of designing adaptive fuzzy-based (or neural network-based) robust controls for a large class of uncertain nonlinear time-varying systems. This class of systems can be perturbed by plant uncertainties, unmodeled perturbations, and external disturbances. Nonlinear H(infinity) control technique incorporated with adaptive control technique and VSC technique is employed to construct the intelligent robust stabilization controller such that an H(infinity) control is achieved. The problem of the robust tracking control design for uncertain robotic systems is employed to demonstrate the effectiveness of the developed robust stabilization control scheme. Therefore, an intelligent robust tracking controller for uncertain robotic systems in the presence of high-degree uncertainties can easily be implemented. Its solution requires only to solve a linear algebraic matrix inequality and a satisfactorily transient and asymptotical tracking performance is guaranteed. A simulation example is made to confirm the performance of the developed control algorithms.

Robust Constrained Optimization Approach to Control Design for International Space Station Centrifuge Rotor Auto Balancing Control System

NASA Technical Reports Server (NTRS)

Postma, Barry Dirk

2005-01-01

This thesis discusses application of a robust constrained optimization approach to control design to develop an Auto Balancing Controller (ABC) for a centrifuge rotor to be implemented on the International Space Station. The design goal is to minimize a performance objective of the system, while guaranteeing stability and proper performance for a range of uncertain plants. The Performance objective is to minimize the translational response of the centrifuge rotor due to a fixed worst-case rotor imbalance. The robustness constraints are posed with respect to parametric uncertainty in the plant. The proposed approach to control design allows for both of these objectives to be handled within the framework of constrained optimization. The resulting controller achieves acceptable performance and robustness characteristics.

Direct adaptive robust tracking control for 6 DOF industrial robot with enhanced accuracy.

PubMed

Yin, Xiuxing; Pan, Li

2018-01-01

A direct adaptive robust tracking control is proposed for trajectory tracking of 6 DOF industrial robot in the presence of parametric uncertainties, external disturbances and uncertain nonlinearities. The controller is designed based on the dynamic characteristics in the working space of the end-effector of the 6 DOF robot. The controller includes robust control term and model compensation term that is developed directly based on the input reference or desired motion trajectory. A projection-type parametric adaptation law is also designed to compensate for parametric estimation errors for the adaptive robust control. The feasibility and effectiveness of the proposed direct adaptive robust control law and the associated projection-type parametric adaptation law have been comparatively evaluated based on two 6 DOF industrial robots. The test results demonstrate that the proposed control can be employed to better maintain the desired trajectory tracking even in the presence of large parametric uncertainties and external disturbances as compared with PD controller and nonlinear controller. The parametric estimates also eventually converge to the real values along with the convergence of tracking errors, which further validate the effectiveness of the proposed parametric adaption law. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Decentralized robust nonlinear model predictive controller for unmanned aerial systems

NASA Astrophysics Data System (ADS)

Garcia Garreton, Gonzalo A.

The nonlinear and unsteady nature of aircraft aerodynamics together with limited practical range of controls and state variables make the use of the linear control theory inadequate especially in the presence of external disturbances, such as wind. In the classical approach, aircraft are controlled by multiple inner and outer loops, designed separately and sequentially. For unmanned aerial systems in particular, control technology must evolve to a point where autonomy is extended to the entire mission flight envelope. This requires advanced controllers that have sufficient robustness, track complex trajectories, and use all the vehicles control capabilities at higher levels of accuracy. In this work, a robust nonlinear model predictive controller is designed to command and control an unmanned aerial system to track complex tight trajectories in the presence of internal and external perturbance. The Flight System developed in this work achieves the above performance by using: 1. A nonlinear guidance algorithm that enables the vehicle to follow an arbitrary trajectory shaped by moving points; 2. A formulation that embeds the guidance logic and trajectory information in the aircraft model, avoiding cross coupling and control degradation; 3. An artificial neural network, designed to adaptively estimate and provide aerodynamic and propulsive forces in real-time; and 4. A mixed sensitivity approach that enhances the robustness for a nonlinear model predictive controller overcoming the effect of un-modeled dynamics, external disturbances such as wind, and measurement additive perturbations, such as noise and biases. These elements have been integrated and tested in simulation and with previously stored flight test data and shown to be feasible.

A Robust Design Methodology for Optimal Microscale Secondary Flow Control in Compact Inlet Diffusers

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Keller, Dennis J.

2001-01-01

It is the purpose of this study to develop an economical Robust design methodology for microscale secondary flow control in compact inlet diffusers. To illustrate the potential of economical Robust Design methodology, two different mission strategies were considered for the subject inlet, namely Maximum Performance and Maximum HCF Life Expectancy. The Maximum Performance mission maximized total pressure recovery while the Maximum HCF Life Expectancy mission minimized the mean of the first five Fourier harmonic amplitudes, i.e., 'collectively' reduced all the harmonic 1/2 amplitudes of engine face distortion. Each of the mission strategies was subject to a low engine face distortion constraint, i.e., DC60<0.10, which is a level acceptable for commercial engines. For each of these missions strategies, an 'Optimal Robust' (open loop control) and an 'Optimal Adaptive' (closed loop control) installation was designed over a twenty degree angle-of-incidence range. The Optimal Robust installation used economical Robust Design methodology to arrive at a single design which operated over the entire angle-of-incident range (open loop control). The Optimal Adaptive installation optimized all the design parameters at each angle-of-incidence. Thus, the Optimal Adaptive installation would require a closed loop control system to sense a proper signal for each effector and modify that effector device, whether mechanical or fluidic, for optimal inlet performance. In general, the performance differences between the Optimal Adaptive and Optimal Robust installation designs were found to be marginal. This suggests, however, that Optimal Robust open loop installation designs can be very competitive with Optimal Adaptive close loop designs. Secondary flow control in inlets is inherently robust, provided it is optimally designed. Therefore, the new methodology presented in this paper, combined array 'Lower Order' approach to Robust DOE, offers the aerodynamicist a very viable and

Internet delivered cognitive behavior therapy for antenatal depression: A randomised controlled trial.

PubMed

Forsell, Erik; Bendix, Marie; Holländare, Fredrik; Szymanska von Schultz, Barbara; Nasiell, Josefine; Blomdahl-Wetterholm, Margareta; Eriksson, Caroline; Kvarned, Sara; Lindau van der Linden, Johanna; Söderberg, Elin; Jokinen, Jussi; Wide, Katarina; Kaldo, Viktor

2017-10-15

Major depression occurs in 5-10% of pregnancies and is associated with many negative effects for mother and child, yet treatment options are scarce. To our knowledge, this is the first published randomised controlled trial on Internet delivered Cognitive Behavior Therapy (ICBT) for this group. To test the efficacy of a pregnancy adapted version of an existing 10-week ICBT-program for depression as well as assessing acceptability and adherence DESIGN: Randomised controlled trial. Online and telephone. Self-referred pregnant women (gestational week 10-28 at intake) currently suffering from major depressive disorder. 42 pregnant women (gestational week 12-28) with major depression were randomised to either treatment as usual (TAU) provided at their antenatal clinic or to ICBT as an add-on to usual care. The primary outcome was depressive symptoms measured with the Montgomery-Åsberg depression rating scale-self report (MADRS-S). The Edinburgh Postnatal Depression Scale and measures of anxiety and sleep were used. Credibility, satisfaction, adherence and utilization were also assessed. The ICBT group had significantly lower levels of depressive symptoms post treatment (p < 0.001, Hedges g =1.21) and were more likely to be responders (i.e. achieve a statistically reliable improvement) (RR = 0.36; p = 0.004). Measures of treatment credibility, satisfaction, utilization, and adherence were comparable to implemented ICBT for depression. Small sample size and no long-term evaluation. Pregnancy adapted ICBT for antenatal depression is feasible, acceptable and efficacious. These results need to be replicated in larger trials to validate these promising findings. Copyright © 2017. Published by Elsevier B.V.

Robust Control for Microgravity Vibration Isolation using Fixed Order, Mixed H2/Mu Design

NASA Technical Reports Server (NTRS)

Whorton, Mark

2003-01-01

Many space-science experiments need an active isolation system to provide a sufficiently quiescent microgravity environment. Modern control methods provide the potential for both high-performance and robust stability in the presence of parametric uncertainties that are characteristic of microgravity vibration isolation systems. While H2 and H(infinity) methods are well established, neither provides the levels of attenuation performance and robust stability in a compensator with low order. Mixed H2/H(infinity), controllers provide a means for maximizing robust stability for a given level of mean-square nominal performance while directly optimizing for controller order constraints. This paper demonstrates the benefit of mixed norm design from the perspective of robustness to parametric uncertainties and controller order for microgravity vibration isolation. A nominal performance metric analogous to the mu measure, for robust stability assessment is also introduced in order to define an acceptable trade space from which different control methodologies can be compared.

Evaluation of Ares-I Control System Robustness to Uncertain Aerodynamics and Flex Dynamics

NASA Technical Reports Server (NTRS)

Jang, Jiann-Woei; VanTassel, Chris; Bedrossian, Nazareth; Hall, Charles; Spanos, Pol

2008-01-01

This paper discusses the application of robust control theory to evaluate robustness of the Ares-I control systems. Three techniques for estimating upper and lower bounds of uncertain parameters which yield stable closed-loop response are used here: (1) Monte Carlo analysis, (2) mu analysis, and (3) characteristic frequency response analysis. All three methods are used to evaluate stability envelopes of the Ares-I control systems with uncertain aerodynamics and flex dynamics. The results show that characteristic frequency response analysis is the most effective of these methods for assessing robustness.

Robust distributed control of spacecraft formation flying with adaptive network topology

NASA Astrophysics Data System (ADS)

Shasti, Behrouz; Alasty, Aria; Assadian, Nima

2017-07-01

In this study, the distributed six degree-of-freedom (6-DOF) coordinated control of spacecraft formation flying in low earth orbit (LEO) has been investigated. For this purpose, an accurate coupled translational and attitude relative dynamics model of the spacecraft with respect to the reference orbit (virtual leader) is presented by considering the most effective perturbation acceleration forces on LEO satellites, i.e. the second zonal harmonic and the atmospheric drag. Subsequently, the 6-DOF coordinated control of spacecraft in formation is studied. During the mission, the spacecraft communicate with each other through a switching network topology in which the weights of its graph Laplacian matrix change adaptively based on a distance-based connectivity function between neighboring agents. Because some of the dynamical system parameters such as spacecraft masses and moments of inertia may vary with time, an adaptive law is developed to estimate the parameter values during the mission. Furthermore, for the case that there is no knowledge of the unknown and time-varying parameters of the system, a robust controller has been developed. It is proved that the stability of the closed-loop system coupled with adaptation in network topology structure and optimality and robustness in control is guaranteed by the robust contraction analysis as an incremental stability method for multiple synchronized systems. The simulation results show the effectiveness of each control method in the presence of uncertainties and parameter variations. The adaptive and robust controllers show their superiority in reducing the state error integral as well as decreasing the control effort and settling time.

Robust control of dielectric elastomer diaphragm actuator for human pulse signal tracking

NASA Astrophysics Data System (ADS)

Ye, Zhihang; Chen, Zheng; Asmatulu, Ramazan; Chan, Hoyin

2017-08-01

Human pulse signal tracking is an emerging technology that is needed in traditional Chinese medicine. However, soft actuation with multi-frequency tracking capability is needed for tracking human pulse signal. Dielectric elastomer (DE) is one type of soft actuating that has great potential in human pulse signal tracking. In this paper, a DE diaphragm actuator was designed and fabricated to track human pulse pressure signal. A physics-based and control-oriented model has been developed to capture the dynamic behavior of DE diaphragm actuator. Using the physical model, an H-infinity robust control was designed for the actuator to reject high-frequency sensing noises and disturbances. The robust control was then implemented in real-time to track a multi-frequency signal, which verified the tracking capability and robustness of the control system. In the human pulse signal tracking test, a human pulse signal was measured at the City University of Hong Kong and then was tracked using DE actuator at Wichita State University in the US. Experimental results have verified that the DE actuator with its robust control is capable of tracking human pulse signal.

A robust fractional-order PID controller design based on active queue management for TCP network

NASA Astrophysics Data System (ADS)

Hamidian, Hamideh; Beheshti, Mohammad T. H.

2018-01-01

In this paper, a robust fractional-order controller is designed to control the congestion in transmission control protocol (TCP) networks with time-varying parameters. Fractional controllers can increase the stability and robustness. Regardless of advantages of fractional controllers, they are still not common in congestion control in TCP networks. The network parameters are time-varying, so the robust stability is important in congestion controller design. Therefore, we focused on the robust controller design. The fractional PID controller is developed based on active queue management (AQM). D-partition technique is used. The most important property of designed controller is the robustness to the time-varying parameters of the TCP network. The vertex quasi-polynomials of the closed-loop characteristic equation are obtained, and the stability boundaries are calculated for each vertex quasi-polynomial. The intersection of all stability regions is insensitive to network parameter variations, and results in robust stability of TCP/AQM system. NS-2 simulations show that the proposed algorithm provides a stable queue length. Moreover, simulations show smaller oscillations of the queue length and less packet drop probability for FPID compared to PI and PID controllers. We can conclude from NS-2 simulations that the average packet loss probability variations are negligible when the network parameters change.

Neural network robust tracking control with adaptive critic framework for uncertain nonlinear systems.

PubMed

Wang, Ding; Liu, Derong; Zhang, Yun; Li, Hongyi

2018-01-01

In this paper, we aim to tackle the neural robust tracking control problem for a class of nonlinear systems using the adaptive critic technique. The main contribution is that a neural-network-based robust tracking control scheme is established for nonlinear systems involving matched uncertainties. The augmented system considering the tracking error and the reference trajectory is formulated and then addressed under adaptive critic optimal control formulation, where the initial stabilizing controller is not needed. The approximate control law is derived via solving the Hamilton-Jacobi-Bellman equation related to the nominal augmented system, followed by closed-loop stability analysis. The robust tracking control performance is guaranteed theoretically via Lyapunov approach and also verified through simulation illustration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Event-Based Robust Control for Uncertain Nonlinear Systems Using Adaptive Dynamic Programming.

PubMed

Zhang, Qichao; Zhao, Dongbin; Wang, Ding

2018-01-01

In this paper, the robust control problem for a class of continuous-time nonlinear system with unmatched uncertainties is investigated using an event-based control method. First, the robust control problem is transformed into a corresponding optimal control problem with an augmented control and an appropriate cost function. Under the event-based mechanism, we prove that the solution of the optimal control problem can asymptotically stabilize the uncertain system with an adaptive triggering condition. That is, the designed event-based controller is robust to the original uncertain system. Note that the event-based controller is updated only when the triggering condition is satisfied, which can save the communication resources between the plant and the controller. Then, a single network adaptive dynamic programming structure with experience replay technique is constructed to approach the optimal control policies. The stability of the closed-loop system with the event-based control policy and the augmented control policy is analyzed using the Lyapunov approach. Furthermore, we prove that the minimal intersample time is bounded by a nonzero positive constant, which excludes Zeno behavior during the learning process. Finally, two simulation examples are provided to demonstrate the effectiveness of the proposed control scheme.

Decentralized adaptive control of robot manipulators with robust stabilization design

NASA Technical Reports Server (NTRS)

Yuan, Bau-San; Book, Wayne J.

1988-01-01

Due to geometric nonlinearities and complex dynamics, a decentralized technique for adaptive control for multilink robot arms is attractive. Lyapunov-function theory for stability analysis provides an approach to robust stabilization. Each joint of the arm is treated as a component subsystem. The adaptive controller is made locally stable with servo signals including proportional and integral gains. This results in the bound on the dynamical interactions with other subsystems. A nonlinear controller which stabilizes the system with uniform boundedness is used to improve the robustness properties of the overall system. As a result, the robot tracks the reference trajectories with convergence. This strategy makes computation simple and therefore facilitates real-time implementation.

Induction of labour versus expectant monitoring for gestational hypertension or mild pre-eclampsia after 36 weeks' gestation (HYPITAT): a multicentre, open-label randomised controlled trial.

PubMed

Koopmans, Corine M; Bijlenga, Denise; Groen, Henk; Vijgen, Sylvia M C; Aarnoudse, Jan G; Bekedam, Dick J; van den Berg, Paul P; de Boer, Karin; Burggraaff, Jan M; Bloemenkamp, Kitty W M; Drogtrop, Addy P; Franx, Arie; de Groot, Christianne J M; Huisjes, Anjoke J M; Kwee, Anneke; van Loon, Aren J; Lub, Annemiek; Papatsonis, Dimitri N M; van der Post, Joris A M; Roumen, Frans J M E; Scheepers, Hubertina C J; Willekes, Christine; Mol, Ben W J; van Pampus, Maria G

2009-09-19

Robust evidence to direct management of pregnant women with mild hypertensive disease at term is scarce. We investigated whether induction of labour in women with a singleton pregnancy complicated by gestational hypertension or mild pre-eclampsia reduces severe maternal morbidity. We undertook a multicentre, parallel, open-label randomised controlled trial in six academic and 32 non-academic hospitals in the Netherlands between October, 2005, and March, 2008. We enrolled patients with a singleton pregnancy at 36-41 weeks' gestation, and who had gestational hypertension or mild pre-eclampsia. Participants were randomly allocated in a 1:1 ratio by block randomisation with a web-based application system to receive either induction of labour or expectant monitoring. Masking of intervention allocation was not possible. The primary outcome was a composite measure of poor maternal outcome--maternal mortality, maternal morbidity (eclampsia, HELLP syndrome, pulmonary oedema, thromboembolic disease, and placental abruption), progression to severe hypertension or proteinuria, and major post-partum haemorrhage (>1000 mL blood loss). Analysis was by intention to treat and treatment effect is presented as relative risk. This study is registered, number ISRCTN08132825. 756 patients were allocated to receive induction of labour (n=377 patients) or expectant monitoring (n=379). 397 patients refused randomisation but authorised use of their medical records. Of women who were randomised, 117 (31%) allocated to induction of labour developed poor maternal outcome compared with 166 (44%) allocated to expectant monitoring (relative risk 0.71, 95% CI 0.59-0.86, p<0.0001). No cases of maternal or neonatal death or eclampsia were recorded. Induction of labour is associated with improved maternal outcome and should be advised for women with mild hypertensive disease beyond 37 weeks' gestation. ZonMw.

The control of the controller: molecular mechanisms for robust perfect adaptation and temperature compensation.

PubMed

Ni, Xiao Yu; Drengstig, Tormod; Ruoff, Peter

2009-09-02

Organisms have the property to adapt to a changing environment and keep certain components within a cell regulated at the same level (homeostasis). "Perfect adaptation" describes an organism's response to an external stepwise perturbation by regulating some of its variables/components precisely to their original preperturbation values. Numerous examples of perfect adaptation/homeostasis have been found, as for example, in bacterial chemotaxis, photoreceptor responses, MAP kinase activities, or in metal-ion homeostasis. Two concepts have evolved to explain how perfect adaptation may be understood: In one approach (robust perfect adaptation), the adaptation is a network property, which is mostly, but not entirely, independent of rate constant values; in the other approach (nonrobust perfect adaptation), a fine-tuning of rate constant values is needed. Here we identify two classes of robust molecular homeostatic mechanisms, which compensate for environmental variations in a controlled variable's inflow or outflow fluxes, and allow for the presence of robust temperature compensation. These two classes of homeostatic mechanisms arise due to the fact that concentrations must have positive values. We show that the concept of integral control (or integral feedback), which leads to robust homeostasis, is associated with a control species that has to work under zero-order flux conditions and does not necessarily require the presence of a physico-chemical feedback structure. There are interesting links between the two identified classes of homeostatic mechanisms and molecular mechanisms found in mammalian iron and calcium homeostasis, indicating that homeostatic mechanisms may underlie similar molecular control structures.

Clinical and cost effectiveness of mobile phone supported self monitoring of asthma: multicentre randomised controlled trial.

PubMed

Ryan, Dermot; Price, David; Musgrave, Stan D; Malhotra, Shweta; Lee, Amanda J; Ayansina, Dolapo; Sheikh, Aziz; Tarassenko, Lionel; Pagliari, Claudia; Pinnock, Hilary

2012-03-23

To determine whether mobile phone based monitoring improves asthma control compared with standard paper based monitoring strategies. Multicentre randomised controlled trial with cost effectiveness analysis. UK primary care. 288 adolescents and adults with poorly controlled asthma (asthma control questionnaire (ACQ) score ≥ 1.5) from 32 practices. Participants were centrally randomised to twice daily recording and mobile phone based transmission of symptoms, drug use, and peak flow with immediate feedback prompting action according to an agreed plan or paper based monitoring. Changes in scores on asthma control questionnaire and self efficacy (knowledge, attitude, and self efficacy asthma questionnaire (KASE-AQ)) at six months after randomisation. Assessment of outcomes was blinded. Analysis was on an intention to treat basis. There was no significant difference in the change in asthma control or self efficacy between the two groups (ACQ: mean change 0.75 in mobile group v 0.73 in paper group, mean difference in change -0.02 (95% confidence interval -0.23 to 0.19); KASE-AQ score: mean change -4.4 v -2.4, mean difference 2.0 (-0.3 to 4.2)). The numbers of patients who had acute exacerbations, steroid courses, and unscheduled consultations were similar in both groups, with similar healthcare costs. Overall, the mobile phone service was more expensive because of the expenses of telemonitoring. Mobile technology does not improve asthma control or increase self efficacy compared with paper based monitoring when both groups received clinical care to guidelines standards. The mobile technology was not cost effective. Clinical Trials NCT00512837.

Angioplasty and stenting for patients with symptomatic intracranial atherosclerosis: study protocol of a randomised controlled trial

PubMed Central

Cui, Xiao-Ping; Lin, Min; Mu, Jun-Shan; Ye, Jian-Xin; He, Wen-Qing; Fu, Mao-Lin; Li, Hua; Fang, Jia-Yang; Shen, Feng-Feng; Lin, Hang

2016-01-01

Introduction Whether adding percutaneous transluminal angioplasty and stenting (PTAS) to background medical treatment is effective for decreasing the incidence of stroke or death in patients with symptomatic intracranial atherosclerosis (ICAS) is still controversial. We perform a randomised controlled trial to examine the effectiveness and safety of an improved PTAS procedure for patients with ICAS. Methods and analysis A randomised controlled trial will be conducted in three hospitals in China. Eligible patients with ICAS will be randomly assigned to receive medication treatment (MT) plus PTAS or MT alone. The MT will be initiated immediately after randomisation, while the PTAS will be performed when patients report relief of alarm symptoms defined as sudden weakness or numbness. All patients will be followed up at 30 days, 3 and 12 months after randomisation. The primary end point will be the incidence of stroke or death at 30 days after randomisation. Secondary outcomes will be the incidence of ischaemic stroke in the territory of stenosis arteries, the incidence of in-stent restenosis, the Chinese version of the modified Rankin Scale and the Chinese version of the Stroke-Specific Quality of Life (CSQoL). Ethics and dissemination The study protocol is approved by institutional review boards in participating hospitals (reference number FZ20160003, 180PLA20160101 and 476PLA2016007). The results of this study will be disseminated to patients, physicians and policymakers through publication in a peer-reviewed journal or presentations in conferences. It is anticipated that the results of this study will improve the quality of the current PTAS procedure and guide clinical decision-making for patients with ICAS. Trial registration number NCT02689037 PMID:27852711

Robust H ∞ Control for Spacecraft Rendezvous with a Noncooperative Target

PubMed Central

Wu, Shu-Nan; Zhou, Wen-Ya; Tan, Shu-Jun; Wu, Guo-Qiang

2013-01-01

The robust H ∞ control for spacecraft rendezvous with a noncooperative target is addressed in this paper. The relative motion of chaser and noncooperative target is firstly modeled as the uncertain system, which contains uncertain orbit parameter and mass. Then the H ∞ performance and finite time performance are proposed, and a robust H ∞ controller is developed to drive the chaser to rendezvous with the non-cooperative target in the presence of control input saturation, measurement error, and thrust error. The linear matrix inequality technology is used to derive the sufficient condition of the proposed controller. An illustrative example is finally provided to demonstrate the effectiveness of the controller. PMID:24027446

Population screening for osteoporosis risk: a randomised control trial of medication use and fracture risk.

PubMed

Barr, R J; Stewart, A; Torgerson, D J; Reid, D M

2010-04-01

Randomised control trial of osteoporosis screening in 4,800 women aged 45-54 years was carried out. Screened group observed an increase of 7.9% in hormone replacement therapy (HRT) use (p < 0.001), 15% in other osteoporosis treatments (p < 0.001) and a 25.9% reduction in fracture risk compared with control. Screening for osteoporosis significantly increases treatment use and reduces fracture incidence. Population screening programmes can identify menopausal women with low bone mineral density (BMD) and elevated risk of future fracture but require to be proven effective by a randomised control trial. A total of 4,800 women, 45-54 years, were randomised in equal numbers to screening or no screening (control) groups. Following screening, those in the lowest quartile of BMD were advised to consider HRT. Nine years later, the effect of screening on the uptake of treatment and the incidence of fractures were assessed by postal questionnaire. Categorical differences were assessed using chi(2) test. Cox regression was used to assess hazard ratio (HR). Of the screened and the control groups, 52.4% vs 44.5%, respectively, reported taking HRT (p < 0.001). In addition, 36.6% of the screened vs 21.6% of the control groups reported the use of vitamin D, calcium, alendronate, etidronate or raloxifene (p < 0.001). In a per protocol analysis of verified incident fractures, a 25.9% reduction in risk of fractures (of any site) in the screened group was observed (HR = 0.741, 95% CI = 0.551-0.998 adjusted age, weight and height). Screening for osteoporosis as assessed by low bone density significantly increases the use of HRT and other treatments for osteoporosis and reduces fracture incidence.

Robust, nonlinear, high angle-of-attack control design for a supermaneuverable vehicle

NASA Technical Reports Server (NTRS)

Adams, Richard J.

1993-01-01

High angle-of-attack flight control laws are developed for a supermaneuverable fighter aircraft. The methods of dynamic inversion and structured singular value synthesis are combined into an approach which addresses both the nonlinearity and robustness problems of flight at extreme operating conditions. The primary purpose of the dynamic inversion control elements is to linearize the vehicle response across the flight envelope. Structured singular value synthesis is used to design a dynamic controller which provides robust tracking to pilot commands. The resulting control system achieves desired flying qualities and guarantees a large margin of robustness to uncertainties for high angle-of-attack flight conditions. The results of linear simulation and structured singular value stability analysis are presented to demonstrate satisfaction of the design criteria. High fidelity nonlinear simulation results show that the combined dynamics inversion/structured singular value synthesis control law achieves a high level of performance in a realistic environment.

Design of a robust control law for the Vega launcher ballistic phase

NASA Astrophysics Data System (ADS)

Valli, Monica; Lavagna, Michèle R.; Panozzo, Thomas

2012-02-01

This work presents the design of a robust control law, and the related control system architecture, for the Vega launcher ballistic phase, taking into account the complete six degrees of freedom dynamics. To gain robustness a non-linear control approach has been preferred: more specifically the Lyapunov's second stability theorem has been exploited, being a very powerful tool to guarantee asymptotic stability of the controlled dynamics. The dynamics of Vega's actuators has also been taken into account. The system performance has been checked and analyzed by numerical simulations run on real mission data for different operational and configuration scenarios, and the effectiveness of the synthesized control highlighted: in particular scenarios including a wide range of composite's inertial configurations performing various typologies of maneuvers have been run. The robustness of the controlled dynamics has been validated by 100 cases Monte Carlo analysis campaign: the containment of the dispersion for the controlled variables - say the composite roll, yaw and pitch angles - confirmed the wide validity and generality of the proposed control law. This paper will show the theoretical approach and discuss the obtained results.

Binocular treatment of amblyopia using videogames (BRAVO): study protocol for a randomised controlled trial.

PubMed

Guo, Cindy X; Babu, Raiju J; Black, Joanna M; Bobier, William R; Lam, Carly S Y; Dai, Shuan; Gao, Tina Y; Hess, Robert F; Jenkins, Michelle; Jiang, Yannan; Kowal, Lionel; Parag, Varsha; South, Jayshree; Staffieri, Sandra Elfride; Walker, Natalie; Wadham, Angela; Thompson, Benjamin

2016-10-18

Amblyopia is a common neurodevelopmental disorder of vision that is characterised by visual impairment in one eye and compromised binocular visual function. Existing evidence-based treatments for children include patching the nonamblyopic eye to encourage use of the amblyopic eye. Currently there are no widely accepted treatments available for adults with amblyopia. The aim of this trial is to assess the efficacy of a new binocular, videogame-based treatment for amblyopia in older children and adults. We hypothesise that binocular treatment will significantly improve amblyopic eye visual acuity relative to placebo treatment. The BRAVO study is a double-blind, randomised, placebo-controlled multicentre trial to assess the effectiveness of a novel videogame-based binocular treatment for amblyopia. One hundred and eight participants aged 7 years or older with anisometropic and/or strabismic amblyopia (defined as ≥0.2 LogMAR interocular visual acuity difference, ≥0.3 LogMAR amblyopic eye visual acuity and no ocular disease) will be recruited via ophthalmologists, optometrists, clinical record searches and public advertisements at five sites in New Zealand, Canada, Hong Kong and Australia. Eligible participants will be randomised by computer in a 1:1 ratio, with stratification by age group: 7-12, 13-17 and 18 years and older. Participants will be randomised to receive 6 weeks of active or placebo home-based binocular treatment. Treatment will be in the form of a modified interactive falling-blocks game, implemented on a 5th generation iPod touch device viewed through red/green anaglyphic glasses. Participants and those assessing outcomes will be blinded to group assignment. The primary outcome is the change in best-corrected distance visual acuity in the amblyopic eye from baseline to 6 weeks post randomisation. Secondary outcomes include distance and near visual acuity, stereopsis, interocular suppression, angle of strabismus (where applicable) measured at

Changing cluster composition in cluster randomised controlled trials: design and analysis considerations

PubMed Central

2014-01-01

Background There are many methodological challenges in the conduct and analysis of cluster randomised controlled trials, but one that has received little attention is that of post-randomisation changes to cluster composition. To illustrate this, we focus on the issue of cluster merging, considering the impact on the design, analysis and interpretation of trial outcomes. Methods We explored the effects of merging clusters on study power using standard methods of power calculation. We assessed the potential impacts on study findings of both homogeneous cluster merges (involving clusters randomised to the same arm of a trial) and heterogeneous merges (involving clusters randomised to different arms of a trial) by simulation. To determine the impact on bias and precision of treatment effect estimates, we applied standard methods of analysis to different populations under analysis. Results Cluster merging produced a systematic reduction in study power. This effect depended on the number of merges and was most pronounced when variability in cluster size was at its greatest. Simulations demonstrate that the impact on analysis was minimal when cluster merges were homogeneous, with impact on study power being balanced by a change in observed intracluster correlation coefficient (ICC). We found a decrease in study power when cluster merges were heterogeneous, and the estimate of treatment effect was attenuated. Conclusions Examples of cluster merges found in previously published reports of cluster randomised trials were typically homogeneous rather than heterogeneous. Simulations demonstrated that trial findings in such cases would be unbiased. However, simulations also showed that any heterogeneous cluster merges would introduce bias that would be hard to quantify, as well as having negative impacts on the precision of estimates obtained. Further methodological development is warranted to better determine how to analyse such trials appropriately. Interim recommendations

A systematic review of randomised controlled trials assessing effectiveness of prosthetic and orthotic interventions

PubMed Central

Farmer, Sybil; Pandyan, Anand; Chockalingam, Nachiappan

2018-01-01

Background Assistive products are items which allow older people and people with disabilities to be able to live a healthy, productive and dignified life. It has been estimated that approximately 1.5% of the world’s population need a prosthesis or orthosis. Objective The objective of this study was to systematically identify and review the evidence from randomized controlled trials assessing effectiveness and cost-effectiveness of prosthetic and orthotic interventions. Methods Literature searches, completed in September 2015, were carried out in fourteen databases between years 1995 and 2015. The search results were independently screened by two reviewers. For the purpose of this manuscript, only randomized controlled trials which examined interventions using orthotic or prosthetic devices were selected for data extraction and synthesis. Results A total of 342 randomised controlled trials were identified (319 English language and 23 non-English language). Only 4 of these randomised controlled trials examined prosthetic interventions and the rest examined orthotic interventions. These orthotic interventions were categorised based on the medical conditions/injuries of the participants. From these studies, this review focused on the medical condition/injuries with the highest number of randomised controlled trials (osteoarthritis, fracture, stroke, carpal tunnel syndrome, plantar fasciitis, anterior cruciate ligament, diabetic foot, rheumatoid and juvenile idiopathic arthritis, ankle sprain, cerebral palsy, lateral epicondylitis and low back pain). The included articles were assessed for risk of bias using the Cochrane Risk of Bias tool. Details of the clinical population examined, the type of orthotic/prosthetic intervention, the comparator/s and the outcome measures were extracted. Effect sizes and odds ratios were calculated for all outcome measures, where possible. Conclusions At present, for prosthetic and orthotic interventions, the scientific literature does

Epidurals in Pancreatic Resection Outcomes (E-PRO) study: protocol for a randomised controlled trial

PubMed Central

Pak, Linda Ma; Haroutounian, Simon; Hawkins, William G; Worley, Lori; Kurtz, Monika; Frey, Karen; Karanikolas, Menelaos; Swarm, Robert A; Bottros, Michael M

2018-01-01

Introduction Epidural analgesia provides an important synergistic method of pain control. In addition to reducing perioperative opioid consumption, the deliverance of analgesia into the epidural space, effectively creating a sympathetic blockade, has a multitude of additional potential benefits, from decreasing the incidence of postoperative delirium to reducing the development of persistent postsurgical pain (PPSP). Prior studies have also identified a correlation between the use of epidural analgesia and improved oncological outcomes and survival. The aim of this study is to evaluate the effect of epidural analgesia in pancreatic operations on immediate postoperative outcomes, the development of PPSP and oncological outcomes in a prospective, single-blind, randomised controlled trial. Methods The Epidurals in Pancreatic Resection Outcomes (E-PRO) study is a prospective, single-centre, randomised controlled trial. 150 patients undergoing either pancreaticoduodenectomy or distal pancreatectomy will be randomised to receive an epidural bupivacaine infusion following anaesthetic induction followed by continued epidural bupivacaine infusion postoperatively in addition to the institutional standardised pain regimen of hydromorphone patient-controlled analgesia (PCA), acetaminophen and ketorolac (intervention group) or no epidural infusion and only the standardised postoperative pain regimen (control group). The primary outcome was the postoperative opioid consumption, measured in morphine or morphine-equivalents. Secondary outcomes include patient-reported postoperative pain numerical rating scores, trend and relative ratios of serum inflammatory markers (interleukin (IL)-1β, IL-6, tumour necrosis factor-α, IL-10), occurrence of postoperative delirium, development of PPSP as determined by quantitative sensory testing, and disease-free and overall survival. Ethics and dissemination The E-PRO trial has been approved by the institutional review board. Recruitment began

Why all randomised controlled trials produce biased results.

PubMed

Krauss, Alexander

2018-06-01

Randomised controlled trials (RCTs) are commonly viewed as the best research method to inform public health and social policy. Usually they are thought of as providing the most rigorous evidence of a treatment's effectiveness without strong assumptions, biases and limitations. This is the first study to examine that hypothesis by assessing the 10 most cited RCT studies worldwide. These 10 RCT studies with the highest number of citations in any journal (up to June 2016) were identified by searching Scopus (the largest database of peer-reviewed journals). This study shows that these world-leading RCTs that have influenced policy produce biased results by illustrating that participants' background traits that affect outcomes are often poorly distributed between trial groups, that the trials often neglect alternative factors contributing to their main reported outcome and, among many other issues, that the trials are often only partially blinded or unblinded. The study here also identifies a number of novel and important assumptions, biases and limitations not yet thoroughly discussed in existing studies that arise when designing, implementing and analysing trials. Researchers and policymakers need to become better aware of the broader set of assumptions, biases and limitations in trials. Journals need to also begin requiring researchers to outline them in their studies. We need to furthermore better use RCTs together with other research methods. Key messages RCTs face a range of strong assumptions, biases and limitations that have not yet all been thoroughly discussed in the literature. This study assesses the 10 most cited RCTs worldwide and shows that trials inevitably produce bias. Trials involve complex processes - from randomising, blinding and controlling, to implementing treatments, monitoring participants etc. - that require many decisions and steps at different levels that bring their own assumptions and degree of bias to results.

Changes in body weight and food choice in those attempting smoking cessation: a cluster randomised controlled trial

PubMed Central

2012-01-01

Background Fear of weight gain is a barrier to smoking cessation and significant cause of relapse for many people. The provision of nutritional advice as part of a smoking cessation programme may assist some in smoking cessation and perhaps limit weight gain. The aim of this study was to determine the effect of a structured programme of dietary advice on weight change and food choice, in adults attempting smoking cessation. Methods Cluster randomised controlled design. Classes randomised to intervention commenced a 24-week intervention, focussed on improving food choice and minimising weight gain. Classes randomised to control received “usual care”. Results Twenty-seven classes in Greater Glasgow were randomised between January and August 2008. Analysis, including those who continued to smoke, showed that actual weight gain and percentage weight gain was similar in both groups. Examination of data for those successful at giving up smoking showed greater mean weight gain in intervention subjects (3.9 (SD 3.1) vs. 2.7 (SD 3.7) kg). Between group differences were not significant (p = 0.23, 95% CI −0.9 to 3.5). In comparison to baseline improved consumption of fruit and vegetables and breakfast cereal were reported in the intervention group. A higher percentage of control participants continued smoking (74% vs. 66%). Conclusions The intervention was not successful at minimising weight gain in comparison to control but was successful in facilitating some sustained improvements in the dietary habits of intervention participants. Improved quit rates in the intervention group suggest that continued contact with advisors may have reduced anxieties regarding weight gain and encouraged cessation despite weight gain. Research should continue in this area as evidence suggests that the negative effects of obesity could outweigh the health benefits achieved through reductions in smoking prevalence. Trial registration Current Controlled Trials ISRCTN73824458 PMID

H∞ Robust Control of a Large-Piston MEMS Micromirror for Compact Fourier Transform Spectrometer Systems.

PubMed

Chen, Huipeng; Li, Mengyuan; Zhang, Yi; Xie, Huikai; Chen, Chang; Peng, Zhangming; Su, Shaohui

2018-02-08

Incorporating linear-scanning micro-electro-mechanical systems (MEMS) micromirrors into Fourier transform spectral acquisition systems can greatly reduce the size of the spectrometer equipment, making portable Fourier transform spectrometers (FTS) possible. How to minimize the tilting of the MEMS mirror plate during its large linear scan is a major problem in this application. In this work, an FTS system has been constructed based on a biaxial MEMS micromirror with a large-piston displacement of 180 μm, and a biaxial H∞ robust controller is designed. Compared with open-loop control and proportional-integral-derivative (PID) closed-loop control, H∞ robust control has good stability and robustness. The experimental results show that the stable scanning displacement reaches 110.9 μm under the H∞ robust control, and the tilting angle of the MEMS mirror plate in that full scanning range falls within ±0.0014°. Without control, the FTS system cannot generate meaningful spectra. In contrast, the FTS yields a clean spectrum with a full width at half maximum (FWHM) spectral linewidth of 96 cm -1 under the H∞ robust control. Moreover, the FTS system can maintain good stability and robustness under various driving conditions.

H∞ Robust Control of a Large-Piston MEMS Micromirror for Compact Fourier Transform Spectrometer Systems

PubMed Central

Li, Mengyuan; Zhang, Yi; Chen, Chang; Peng, Zhangming; Su, Shaohui

2018-01-01

Incorporating linear-scanning micro-electro-mechanical systems (MEMS) micromirrors into Fourier transform spectral acquisition systems can greatly reduce the size of the spectrometer equipment, making portable Fourier transform spectrometers (FTS) possible. How to minimize the tilting of the MEMS mirror plate during its large linear scan is a major problem in this application. In this work, an FTS system has been constructed based on a biaxial MEMS micromirror with a large-piston displacement of 180 μm, and a biaxial H∞ robust controller is designed. Compared with open-loop control and proportional-integral-derivative (PID) closed-loop control, H∞ robust control has good stability and robustness. The experimental results show that the stable scanning displacement reaches 110.9 μm under the H∞ robust control, and the tilting angle of the MEMS mirror plate in that full scanning range falls within ±0.0014°. Without control, the FTS system cannot generate meaningful spectra. In contrast, the FTS yields a clean spectrum with a full width at half maximum (FWHM) spectral linewidth of 96 cm−1 under the H∞ robust control. Moreover, the FTS system can maintain good stability and robustness under various driving conditions. PMID:29419765

Robust stability bounds for multi-delay networked control systems

NASA Astrophysics Data System (ADS)

Seitz, Timothy; Yedavalli, Rama K.; Behbahani, Alireza

2018-04-01

In this paper, the robust stability of a perturbed linear continuous-time system is examined when controlled using a sampled-data networked control system (NCS) framework. Three new robust stability bounds on the time-invariant perturbations to the original continuous-time plant matrix are presented guaranteeing stability for the corresponding discrete closed-loop augmented delay-free system (ADFS) with multiple time-varying sensor and actuator delays. The bounds are differentiated from previous work by accounting for the sampled-data nature of the NCS and for separate communication delays for each sensor and actuator, not a single delay. Therefore, this paper expands the knowledge base in multiple inputs multiple outputs (MIMO) sampled-data time delay systems. Bounds are presented for unstructured, semi-structured, and structured perturbations.

Cognitive rehabiliation for Parkinson's disease demantia: a study protocol for a pilot randomised controlled trial.

PubMed

Hindle, John V; Watermeyer, Tamlyn J; Roberts, Julie; Martyr, Anthony; Lloyd-Williams, Huw; Brand, Andrew; Gutting, Petra; Hoare, Zoe; Edwards, Rhiannon Tudor; Clare, Linda

2016-03-22

There is growing interest in developing non-pharmacological treatments to address the cognitive deficits apparent in Parkinson's disease dementia and dementia with Lewy bodies. Cognitive rehabilitation is a goal-oriented behavioural intervention which focuses on improving everyday functioning through management of cognitive difficulties; it has been shown to be effective in Alzheimer's disease. To date, no studies have assessed its potential efficacy for addressing the impact of cognitive impairment in people with Parkinson's disease or dementia with Lewy bodies. Participants (n = 45) will be recruited from movement disorders, care for the elderly and memory clinics. Inclusion criteria include: a diagnosis of Parkinson's disease, Parkinson's disease dementia or dementia with Lewy bodies according to consensus criteria and an Addenbrooke's Cognitive Examination - III score of ≤ 82. Exclusion criteria include: a diagnosis of any other significant neurological condition; major psychiatric disorder, including depression, which is not related to the patient's Parkinson's disease and unstable medication use for their physical or cognitive symptoms. A single-blind pilot randomised controlled trial, with concurrent economic evaluation, will compare the relative efficacy of cognitive rehabilitation with that of two control conditions. Following a goal-setting interview, the participants will be randomised to one of the three study arms: cognitive rehabilitation (eight weekly sessions), relaxation therapy (eight weekly sessions) or treatment as usual. Randomisation and treatment group allocation will be carried out by a clinical trials unit using a dynamic adaptive sequential randomisation algorithm. The primary outcomes are patients' perceived goal attainment at a 2-months post-intervention assessment and a 6-months follow-up. Secondary outcomes include patients' objective cognitive performance (on tests of memory and executive function) and satisfaction with goal

'Putting Life in Years' (PLINY) telephone friendship groups research study: pilot randomised controlled trial.

PubMed

Mountain, Gail A; Hind, Daniel; Gossage-Worrall, Rebecca; Walters, Stephen J; Duncan, Rosie; Newbould, Louise; Rex, Saleema; Jones, Carys; Bowling, Ann; Cattan, Mima; Cairns, Angela; Cooper, Cindy; Edwards, Rhiannon Tudor; Goyder, Elizabeth C

2014-04-24

Loneliness in older people is associated with poor health-related quality of life (HRQoL). We undertook a parallel-group randomised controlled trial to evaluate the effectiveness and cost-effectiveness of telephone befriending for the maintenance of HRQoL in older people. An internal pilot tested the feasibility of the trial and intervention. Participants aged >74 years, with good cognitive function, living independently in one UK city were recruited through general practices and other sources, then randomised to: (1) 6 weeks of short one-to-one telephone calls, followed by 12 weeks of group telephone calls with up to six participants, led by a trained volunteer facilitator; or (2) a control group. The main trial required the recruitment of 248 participants in a 1-year accrual window, of whom 124 were to receive telephone befriending. The pilot specified three success criteria which had to be met in order to progress the main trial to completion: recruitment of 68 participants in 95 days; retention of 80% participants at 6 months; successful delivery of telephone befriending by local franchise of national charity. The primary clinical outcome was the Short Form (36) Health Instrument (SF-36) Mental Health (MH) dimension score collected by telephone 6 months following randomisation. We informed 9,579 older people about the study. Seventy consenting participants were randomised to the pilot in 95 days, with 56 (80%) providing valid primary outcome data (26 intervention, 30 control). Twenty-four participants randomly allocated to the research arm actually received telephone befriending due to poor recruitment and retention of volunteer facilitators. The trial was closed early as a result. The mean 6-month SF-36 MH scores were 78 (SD 18) and 71 (SD 21) for the intervention and control groups, respectively (mean difference, 7; 95% CI, -3 to 16). Recruitment and retention of participants to a definitive trial with a recruitment window of 1 year is feasible. For

Cluster randomised controlled trial of 'whole school' child maltreatment prevention programme in primary schools in Northern Ireland: study protocol for Keeping Safe.

PubMed

McElearney, Aisling; Brennan-Wilson, Aoibheann; Murphy, Christina; Stephenson, Phyllis; Bunting, Brendan

2018-05-03

Child maltreatment has a pervasive, detrimental impact on children's wellbeing. Despite a growing focus on prevention through school based education, few programmes adopt a whole- school approach, are multi-component, seek to address all forms of maltreatment, or indeed have been robustly evaluated. This paper describes a cluster randomised controlled trial designed to evaluate a school based child maltreatment prevention programme: 'Keeping Safe' in primary schools in Northern Ireland. The intervention has been designed by a non-profit agency. Programme resources include 63 lessons taught incrementally to children between four and 11 years old, and is premised on three core themes: healthy relationships, my body, and being safe. There are programme resources to engage parents and to build the capacity and skills of school staff. A cluster Randomised Controlled Trial (RCT) will be conducted with children in 80 schools over a two-year period. The unit of randomisation is the school. Schools will be allocated to intervention or wait-list control groups using a computer-generated list. Data will be collected at three time points: baseline, end of year one, and end of year two of programme implementation. Primary outcomes will include: children's understanding of key programme concepts, self-efficacy to keep safe in situations of maltreatment, anxiety arising from programme participation, and disclosure of maltreatment. Secondary outcomes include teachers' comfort and confidence in teaching the programme and parents' confidence in talking to their children about programme concepts. This RCT will address gaps in current practice and evidence regarding school based child maltreatment prevention programmes. This includes the use of a whole- school approach and multi-component programme that addresses all maltreatment concepts, a two-year period of programme implementation, and the tracking of outcomes for children, parents, and teachers. Methodologically, it will extend

Robust control for fractional variable-order chaotic systems with non-singular kernel

NASA Astrophysics Data System (ADS)

Zuñiga-Aguilar, C. J.; Gómez-Aguilar, J. F.; Escobar-Jiménez, R. F.; Romero-Ugalde, H. M.

2018-01-01

This paper investigates the chaos control for a class of variable-order fractional chaotic systems using robust control strategy. The variable-order fractional models of the non-autonomous biological system, the King Cobra chaotic system, the Halvorsen's attractor and the Burke-Shaw system, have been derived using the fractional-order derivative with Mittag-Leffler in the Liouville-Caputo sense. The fractional differential equations and the control law were solved using the Adams-Bashforth-Moulton algorithm. To test the control stability efficiency, different statistical indicators were introduced. Finally, simulation results demonstrate the effectiveness of the proposed robust control.

HeLP-Diabetes: randomised controlled trial protocol.

PubMed

Murray, Elizabeth; Dack, Charlotte; Barnard, Maria; Farmer, Andrew; Li, Jinshuo; Michie, Susan; Pal, Kingshuk; Parrott, Steve; Ross, Jamie; Sweeting, Michael; Wood, Bindie; Yardley, Lucy

2015-12-29

Type 2 Diabetes Mellitus (T2DM) is common, affecting nearly 400 million people worldwide. Achieving good health for people with T2DM requires active self-management; however, uptake of self-management education is poor, and there is an urgent need to find better, more acceptable, cost-effective methods of providing self-management support. Web-based self-management support has many potential benefits for patients and health services. The aim of this trial is to determine the effectiveness and cost-effectiveness of a web-based self-management support programme for people with T2DM. This will be a multi-centre individually randomised controlled trial in primary care, recruiting adults with T2DM who are registered with participating general practices in England. Participants will be randomised to receive either an evidence-based, theoretically informed, web-based self-management programme for people with T2DM which addresses medical, emotional, and role management, called Healthy Living for People with type 2 Diabetes (HeLP-Diabetes) or a simple information website. The joint primary outcomes are glycated haemoglobin (HbA1c) and diabetes-related distress, measured by the Problem Areas In Diabetes (PAID) questionnaire. Secondary outcomes include cardiovascular risk factors, depression and anxiety, and self-efficacy for self-management of diabetes. Health economic data include health service use, costs due to the intervention, and EQ-5D for calculation of Quality Adjusted Life Years (QALYS). Data will be collected at baseline, 3 months and 12 months, with the primary endpoint at 12 months. Practice nurses, blinded to patient allocation, collect clinical data; patients complete online questionnaires for patient reported measures. A sample size of 350 recruited participants allows for attrition of up to 15 % and will provide 90 % power of detecting at a 5 % significance level a true average difference in the PAID score of 4.0 and 0.25 % change in HbA1c (both small effect

Robust PD Sway Control of a Lifted Load for a Crane Using a Genetic Algorithm

NASA Astrophysics Data System (ADS)

Kawada, Kazuo; Sogo, Hiroyuki; Yamamoto, Toru; Mada, Yasuhiro

PID control schemes still continue to be widely used for most industrial control systems. This is mainly because PID controllers have simple control structures, and are simple to maintain and tune. However, it is difficult to find a set of suitable control parameters in the case of time-varying and/or nonlinear systems. For such a problem, the robust controller has been proposed.Although it is important to choose the suitable nominal model in designing the robust controller, it is not usually easy.In this paper, a new robust PD controller design scheme is proposed, which utilizes a genetic algorithm.

Evaluation of a novel information resource for patients with bronchiectasis: study protocol for a randomised controlled trial.

PubMed

Hester, Katy L M; Newton, Julia; Rapley, Tim; De Soyza, Anthony

2016-04-23

There is currently little patient information on bronchiectasis, a chronic lung disease with rising prevalence. Previous work shows that patients and their families want more information, which could potentially improve their understanding and self-management. Using interviews and focus groups, we have co-developed a novel patient and carer information resource, aiming to meet their identified needs. The aims and objectives are: 1. To assess the potential impact of the information resource 2. To evaluate and refine the intervention 3. To establish the feasibility of carrying out a multi-centre randomised controlled trial to determine its effect on understanding, self-management and health outcomes This is a feasibility study, with a single-centre, randomised controlled trial design, comparing use of a novel patient information resource to usual care in bronchiectasis. Additionally, patients and carers will be invited to focus groups to discuss their views on both the intervention itself and the trial process. The study duration for each participant will be 3 months from the study entry date. A total of 70 patients will be recruited to the study, and a minimum of 30 will be randomised to each arm. Ten participants (and their carers if applicable) will be invited to attend focus groups on completion of the study visits. Participants will be adults with bronchiectasis diagnosed as per national bronchiectasis guidelines. Once consented, participants will be randomised to the intervention or control arm using random permuted blocks to ensure treatment group numbers are evenly balanced. Randomisation will be web-based. Those randomised to the intervention will receive the information resource (website and booklet) and instructions on its use. Outcome measures (resource satisfaction, resource use and alternative information seeking, quality of life questionnaires, unscheduled healthcare visits, exacerbation frequency, bronchiectasis knowledge questionnaire and lung

Enzyme potentiated desensitisation in treatment of seasonal allergic rhinitis: double blind randomised controlled study.

PubMed

Radcliffe, Michael J; Lewith, George T; Turner, Richard G; Prescott, Philip; Church, Martin K; Holgate, Stephen T

2003-08-02

To assess the efficacy of enzyme potentiated desensitisation in the treatment of severe summer hay fever poorly controlled by pharmacotherapy. Double blind randomised placebo controlled parallel group study. Hospital in Hampshire. 183 participants aged between 18 and 64 with a history of severe summer hay fever for at least two years; all were skin prick test positive to timothy grass pollen. 90 randomised to active treatment; 93 randomised to placebo. Active treatment: two injections of enzyme potentiated desensitisation, given between eight and 11 weeks apart, each comprising 200 Fishman units of beta glucuronidase, 50 pg 1,3-cyclohexanediol, 50 ng protamine sulphate, and a mixed inhaled allergen extract (pollen mixes for trees, grasses, and weeds; allergenic fungal spores; cat and dog danders; dust and storage mites) in a total volume of 0.05 ml of buffered saline. Placebo: two injections of 0.05 ml buffered saline solution. Proportion of problem-free days; global rhinoconjunctivitis quality of life scores assessed weekly during pollen season. The active treatment group and the placebo group did not differ in the proportion of problem-free days, quality of life scores, symptom severity scores, change in quantitative skin prick provocation threshold, or change in conjunctival provocation threshold. No clinically significant adverse reactions occurred. Enzyme potentiated desensitisation showed no treatment effect in this study.

Enzyme potentiated desensitisation in treatment of seasonal allergic rhinitis: double blind randomised controlled study

PubMed Central

Radcliffe, Michael J; Lewith, George T; Turner, Richard G; Prescott, Philip; Church, Martin K; Holgate, Stephen T

2003-01-01

Objective To assess the efficacy of enzyme potentiated desensitisation in the treatment of severe summer hay fever poorly controlled by pharmacotherapy. Design Double blind randomised placebo controlled parallel group study. Setting Hospital in Hampshire. Participants 183 participants aged between 18 and 64 with a history of severe summer hay fever for at least two years; all were skin prick test positive to timothy grass pollen. 90 randomised to active treatment; 93 randomised to placebo. Interventions Active treatment: two injections of enzyme potentiated desensitisation, given between eight and 11 weeks apart, each comprising 200 Fishman units of β glucuronidase, 50 pg 1,3-cyclohexanediol, 50 ng protamine sulphate, and a mixed inhaled allergen extract (pollen mixes for trees, grasses, and weeds; allergenic fungal spores; cat and dog danders; dust and storage mites) in a total volume of 0.05 ml of buffered saline. Placebo: two injections of 0.05 ml buffered saline solution. Main outcome measures Proportion of problem-free days; global rhinoconjunctivitis quality of life scores assessed weekly during pollen season. Results The active treatment group and the placebo group did not differ in the proportion of problem-free days, quality of life scores, symptom severity scores, change in quantitative skin prick provocation threshold, or change in conjunctival provocation threshold. No clinically significant adverse reactions occurred. Conclusions Enzyme potentiated desensitisation showed no treatment effect in this study. PMID:12896934

Lee Silverman Voice Treatment versus standard speech and language therapy versus control in Parkinson's disease: a pilot randomised controlled trial (PD COMM pilot).

PubMed

Sackley, Catherine M; Smith, Christina H; Rick, Caroline E; Brady, Marian C; Ives, Natalie; Patel, Smitaa; Woolley, Rebecca; Dowling, Francis; Patel, Ramilla; Roberts, Helen; Jowett, Sue; Wheatley, Keith; Kelly, Debbie; Sands, Gina; Clarke, Carl E

2018-01-01

Speech-related problems are common in Parkinson's disease (PD), but there is little evidence for the effectiveness of standard speech and language therapy (SLT) or Lee Silverman Voice Treatment (LSVT LOUD®). The PD COMM pilot was a three-arm, assessor-blinded, randomised controlled trial (RCT) of LSVT LOUD®, SLT and no intervention (1:1:1 ratio) to assess the feasibility and to inform the design of a full-scale RCT. Non-demented patients with idiopathic PD and speech problems and no SLT for speech problems in the past 2 years were eligible. LSVT LOUD® is a standardised regime (16 sessions over 4 weeks). SLT comprised individualised content per local practice (typically weekly sessions for 6-8 weeks). Outcomes included recruitment and retention, treatment adherence, and data completeness. Outcome data collected at baseline, 3, 6, and 12 months included patient-reported voice and quality of life measures, resource use, and assessor-rated speech recordings. Eighty-nine patients were randomised with 90% in the therapy groups and 100% in the control group completing the trial. The response rate for Voice Handicap Index (VHI) in each arm was ≥ 90% at all time-points. VHI was highly correlated with the other speech-related outcome measures. There was a trend to improvement in VHI with LSVT LOUD® (difference at 3 months compared with control: - 12.5 points; 95% CI - 26.2, 1.2) and SLT (difference at 3 months compared with control: - 9.8 points; 95% CI - 23.2, 3.7) which needs to be confirmed in an adequately powered trial. Randomisation to a three-arm trial of speech therapy including a no intervention control is feasible and acceptable. Compliance with both interventions was good. VHI and other patient-reported outcomes were relevant measures and provided data to inform the sample size for a substantive trial. International Standard Randomised Controlled Trial Number Register: ISRCTN75223808. registered 22 March 2012.

Robust integrated flight/propulsion control design for a STOVL aircraft using H-infinity control design techniques

NASA Technical Reports Server (NTRS)

Garg, Sanjay

1993-01-01

Results are presented from an application of H-infinity control design methodology to a centralized integrated flight/propulsion control (IFPC) system design for a supersonic STOVL fighter aircraft in transition flight. The emphasis is on formulating the H-infinity optimal control synthesis problem such that the critical requirements for the flight and propulsion systems are adequately reflected within the linear, centralized control problem formulation and the resulting controller provides robustness to modeling uncertainties and model parameter variations with flight condition. Detailed evaluation results are presented for a reduced order controller obtained from the improved H-infinity control design showing that the control design meets the specified nominal performance objective as well as provides stability robustness for variations in plant system dynamics with changes in aircraft trim speed within the transition flight envelope.

A hybrid robust fault tolerant control based on adaptive joint unscented Kalman filter.

PubMed

Shabbouei Hagh, Yashar; Mohammadi Asl, Reza; Cocquempot, Vincent

2017-01-01

In this paper, a new hybrid robust fault tolerant control scheme is proposed. A robust H ∞ control law is used in non-faulty situation, while a Non-Singular Terminal Sliding Mode (NTSM) controller is activated as soon as an actuator fault is detected. Since a linear robust controller is designed, the system is first linearized through the feedback linearization method. To switch from one controller to the other, a fuzzy based switching system is used. An Adaptive Joint Unscented Kalman Filter (AJUKF) is used for fault detection and diagnosis. The proposed method is based on the simultaneous estimation of the system states and parameters. In order to show the efficiency of the proposed scheme, a simulated 3-DOF robotic manipulator is used. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Children, parents, and pets exercising together (CPET) randomised controlled trial: study rationale, design, and methods.

PubMed

Yam, Philippa S; Morrison, Ryan; Penpraze, Viki; Westgarth, Carri; Ward, Dianne S; Mutrie, Nanette; Hutchison, Pippa; Young, David; Reilly, John J

2012-03-19

Objectively measured physical activity is low in British children, and declines as childhood progresses. Observational studies suggest that dog-walking might be a useful approach to physical activity promotion in children and adults, but there are no published public health interventions based on dog-walking with children. The Children, Parents, and Pets Exercising Together Study aims to develop and evaluate a theory driven, generalisable, family-based, dog walking intervention for 9-11 year olds. The Children, Parents, and Pets Exercising Together Study is an exploratory, assessor-blinded, randomised controlled trial as defined in the UK MRC Framework on the development and evaluation of complex interventions in public health. The trial will follow CONSORT guidance. Approximately 40 dog-owning families will be allocated randomly in a ratio of 1.5:1 to receive a simple behavioural intervention lasting for 10 weeks or to a 'waiting list' control group. The primary outcome is change in objectively measured child physical activity using Actigraph accelerometry. Secondary outcomes in the child, included in part to shape a future more definitive randomised controlled trial, are: total time spent sedentary and patterning of sedentary behaviour (Actigraph accelerometry); body composition and bone health from dual energy x-ray absorptiometry; body weight, height and BMI; and finally, health-related quality of life using the PedsQL. Secondary outcomes in parents and dogs are: changes in body weight; changes in Actigraph accelerometry measured physical activity and sedentary behaviour. Process evaluation will consist of assessment of simultaneous child, parent, and dog accelerometry data and brief interviews with participating families. The Children, Parents, and Pets Exercising Together trial should be the first randomised controlled study to establish and evaluate an intervention aimed at dog-based physical activity promotion in families. It should advance our

Children, parents, and pets exercising together (CPET) randomised controlled trial: study rationale, design, and methods

PubMed Central

2012-01-01

Background Objectively measured physical activity is low in British children, and declines as childhood progresses. Observational studies suggest that dog-walking might be a useful approach to physical activity promotion in children and adults, but there are no published public health interventions based on dog-walking with children. The Children, Parents, and Pets Exercising Together Study aims to develop and evaluate a theory driven, generalisable, family-based, dog walking intervention for 9-11 year olds. Methods/design The Children, Parents, and Pets Exercising Together Study is an exploratory, assessor-blinded, randomised controlled trial as defined in the UK MRC Framework on the development and evaluation of complex interventions in public health. The trial will follow CONSORT guidance. Approximately 40 dog-owning families will be allocated randomly in a ratio of 1.5:1 to receive a simple behavioural intervention lasting for 10 weeks or to a 'waiting list' control group. The primary outcome is change in objectively measured child physical activity using Actigraph accelerometry. Secondary outcomes in the child, included in part to shape a future more definitive randomised controlled trial, are: total time spent sedentary and patterning of sedentary behaviour (Actigraph accelerometry); body composition and bone health from dual energy x-ray absorptiometry; body weight, height and BMI; and finally, health-related quality of life using the PedsQL. Secondary outcomes in parents and dogs are: changes in body weight; changes in Actigraph accelerometry measured physical activity and sedentary behaviour. Process evaluation will consist of assessment of simultaneous child, parent, and dog accelerometry data and brief interviews with participating families. Discussion The Children, Parents, and Pets Exercising Together trial should be the first randomised controlled study to establish and evaluate an intervention aimed at dog-based physical activity promotion in

Uncertainty analysis and robust trajectory linearization control of a flexible air-breathing hypersonic vehicle

NASA Astrophysics Data System (ADS)

Pu, Zhiqiang; Tan, Xiangmin; Fan, Guoliang; Yi, Jianqiang

2014-08-01

Flexible air-breathing hypersonic vehicles feature significant uncertainties which pose huge challenges to robust controller designs. In this paper, four major categories of uncertainties are analyzed, that is, uncertainties associated with flexible effects, aerodynamic parameter variations, external environmental disturbances, and control-oriented modeling errors. A uniform nonlinear uncertainty model is explored for the first three uncertainties which lumps all uncertainties together and consequently is beneficial for controller synthesis. The fourth uncertainty is additionally considered in stability analysis. Based on these analyses, the starting point of the control design is to decompose the vehicle dynamics into five functional subsystems. Then a robust trajectory linearization control (TLC) scheme consisting of five robust subsystem controllers is proposed. In each subsystem controller, TLC is combined with the extended state observer (ESO) technique for uncertainty compensation. The stability of the overall closed-loop system with the four aforementioned uncertainties and additional singular perturbations is analyzed. Particularly, the stability of nonlinear ESO is also discussed from a Liénard system perspective. At last, simulations demonstrate the great control performance and the uncertainty rejection ability of the robust scheme.

Comparison of anticipated and actual control group outcomes in randomised trials in paediatric oncology provides evidence that historically controlled studies are biased in favour of the novel treatment.

PubMed

Moroz, Veronica; Wilson, Jayne S; Kearns, Pamela; Wheatley, Keith

2014-12-10

Historically controlled studies are commonly undertaken in paediatric oncology, despite their potential biases. Our aim was to compare the outcome of the control group in randomised controlled trials (RCTs) in paediatric oncology with those anticipated in the sample size calculations in the protocols. Our rationale was that, had these RCTs been performed as historical control studies instead, the available outcome data used to calculate the sample size in the RCT would have been used as the historical control outcome data. A systematic search was undertaken for published paediatric oncology RCTs using the Cochrane Central Register of Controlled Trials (CENTRAL) database from its inception up to July 2013. Data on sample size assumptions and observed outcomes (timetoevent and proportions) were extracted to calculate differences between randomised and historical control outcomes, and a one-sample t-test was employed to assess whether the difference between anticipated and observed control groups differed from zero. Forty-eight randomised questions were included. The median year of publication was 2005, and the range was from 1976 to 2010. There were 31 superiority and 11 equivalence/noninferiority randomised questions with time-to-event outcomes. The median absolute difference between observed and anticipated control outcomes was 5.0% (range: -23 to +34), and the mean difference was 3.8% (95% CI: +0.57 to +7.0; P = 0.022). Because the observed control group (that is, standard treatment arm) in RCTs performed better than anticipated, we found that historically controlled studies that used similar assumptions for the standard treatment were likely to overestimate the benefit of new treatments, potentially leading to children with cancer being given ineffective therapy that may have additional toxicity.

Total or Partial Knee Arthroplasty Trial - TOPKAT: study protocol for a randomised controlled trial

PubMed Central

2013-01-01

Background In the majority of patients with osteoarthritis of the knee the disease originates in the medial compartment. There are two fundamentally different approaches to knee replacement for patients with unicompartmental disease: some surgeons feel that it is always best to replace both the knee compartments with a total knee replacement (TKR); whereas others feel it is best to replace just the damaged component of the knee using a partial or unicompartment replacement (UKR). Both interventions are established and well-documented procedures. Little evidence exists to prove the clinical and cost-effectiveness of either management option. This provides an explanation for the high variation in treatment of choice by individual surgeons for the same knee pathology. The aim of the TOPKAT study will be to assess the clinical and cost effectiveness of TKRs compared to UKRs in patients with medial compartment osteoarthritis. Methods/Design The design of the study is a single layer multicentre superiority type randomised controlled trial of unilateral knee replacement patients. Blinding will not be possible as the surgical scars for each procedure differ. We aim to recruit 500 patients from approximately 28 secondary care orthopaedic units from across the UK including district general and teaching hospitals. Participants will be randomised to either UKR or TKR. Randomisation will occur using a web-based randomisation system. The study is pragmatic in terms of implant selection for the knee replacement operation. Participants will be followed up for 5 years. The primary outcome is the Oxford Knee Score, which will be collected via questionnaires at 2 months, 1 year and then annually to 5 years. Secondary outcomes will include cost-effectiveness, patient satisfaction and complications data. Trial registration Current Controlled Trials ISRCTN03013488; ClinicalTrials.gov Identifier: NCT01352247 PMID:24028414

Language Measure for Robust Optimal Control

DTIC Science & Technology

2006-01-01

ROBUST OPTIMAL CONTROL 6. AUTHOR(S) Asok Ray , Travis Ortogero 5. FUNDING NUMBERS C - F30602-01-2-0575 PE - 62301E PR - M414...element of Π is non-negative, so each element of kΠ is also. Thus, 0][ 1 ≥Π− −I elementwise. ■ Wang and Ray [WR02] and Ray and Phoha [RP02] have...Sell, Linear Operator Theory in Science and Engineering, Springer-Verlag, New York, 1982. [RP02] A. Ray and S. Phoha, “A language measure for

When is a randomised controlled trial health equity relevant? Development and validation of a conceptual framework

PubMed Central

Jull, J; Whitehead, M; Petticrew, M; Kristjansson, E; Gough, D; Petkovic, J; Volmink, J; Weijer, C; Taljaard, M; Edwards, S; Mbuagbaw, L; Cookson, R; McGowan, J; Lyddiatt, A; Boyer, Y; Cuervo, L G; Armstrong, R; White, H; Yoganathan, M; Pantoja, T; Shea, B; Pottie, K; Norheim, O; Baird, S; Robberstad, B; Sommerfelt, H; Asada, Y; Wells, G; Tugwell, P; Welch, V

2017-01-01

Background Randomised controlled trials can provide evidence relevant to assessing the equity impact of an intervention, but such information is often poorly reported. We describe a conceptual framework to identify health equity-relevant randomised trials with the aim of improving the design and reporting of such trials. Methods An interdisciplinary and international research team engaged in an iterative consensus building process to develop and refine the conceptual framework via face-to-face meetings, teleconferences and email correspondence, including findings from a validation exercise whereby two independent reviewers used the emerging framework to classify a sample of randomised trials. Results A randomised trial can usefully be classified as ‘health equity relevant’ if it assesses the effects of an intervention on the health or its determinants of either individuals or a population who experience ill health due to disadvantage defined across one or more social determinants of health. Health equity-relevant randomised trials can either exclusively focus on a single population or collect data potentially useful for assessing differential effects of the intervention across multiple populations experiencing different levels or types of social disadvantage. Trials that are not classified as ‘health equity relevant’ may nevertheless provide information that is indirectly relevant to assessing equity impact, including information about individual level variation unrelated to social disadvantage and potentially useful in secondary modelling studies. Conclusion The conceptual framework may be used to design and report randomised trials. The framework could also be used for other study designs to contribute to the evidence base for improved health equity. PMID:28951402

Risk of bias assessment of randomised controlled trials in high-impact ophthalmology journals and general medical journals: a systematic review.

PubMed

Joksimovic, Lazar; Koucheki, Robert; Popovic, Marko; Ahmed, Yusuf; Schlenker, Matthew B; Ahmed, Iqbal Ike K

2017-10-01

Evidence-based treatments in ophthalmology are often based on the results of randomised controlled trials. Biased conclusions from randomised controlled trials may lead to inappropriate management recommendations. This systematic review investigates the prevalence of bias risk in randomised controlled trials published in high-impact ophthalmology journals and ophthalmology trials from general medical journals. Using Ovid MEDLINE, randomised controlled trials in the top 10 high-impact ophthalmology journals in 2015 were systematically identified and critically appraised for the prevalence of bias risk. Included randomised controlled trials were assessed in all domains of bias as defined by the Cochrane Collaboration. In addition, the prevalence of conflict of interest and industry sponsorship was investigated. A comparison with ophthalmology articles from high-impact general medical journals was performed. Of the 259 records that were screened from ophthalmology-specific journals, 119 trials met all inclusion criteria and were critically appraised. In total, 29.4% of domains had an unclear risk, 13.8% had a high risk and 56.8% had a low risk of bias. In comparison, ophthalmology articles from general medical journals had a lower prevalence of unclear risk (17.1%), higher prevalence of high risk (21.9%) and a higher prevalence of low risk domains (61.9%). Furthermore, 64.7% of critically appraised trials from ophthalmology-specific journals did not report any conflicts of interest, while 70.6% did not report an industry sponsor of their trial. In closing, it is essential that authors, peer reviewers and readers closely follow published risk of bias guidelines. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Limiting weight gain in overweight and obese women during pregnancy to improve health outcomes: the LIMIT randomised controlled trial

PubMed Central

2011-01-01

Background Obesity is a significant global health problem, with the proportion of women entering pregnancy with a body mass index greater than or equal to 25 kg/m2 approaching 50%. Obesity during pregnancy is associated with a well-recognised increased risk of adverse health outcomes both for the woman and her infant, however there is more limited information available regarding effective interventions to improve health outcomes. The aims of this randomised controlled trial are to assess whether the implementation of a package of dietary and lifestyle advice to overweight and obese women during pregnancy to limit gestational weight gain is effective in improving maternal, fetal and infant health outcomes. Methods/Design Design: Multicentred randomised, controlled trial. Inclusion Criteria: Women with a singleton, live gestation between 10+0-20+0 weeks who are obese or overweight (defined as body mass index greater than or equal to 25 kg/m2), at the first antenatal visit. Trial Entry & Randomisation: Eligible, consenting women will be randomised between 10+0 and 20+0 weeks gestation using a central telephone randomisation service, and randomisation schedule prepared by non-clinical research staff with balanced variable blocks. Stratification will be according to maternal BMI at trial entry, parity, and centre where planned to give birth. Treatment Schedules: Women randomised to the Dietary and Lifestyle Advice Group will receive a series of inputs from research assistants and research dietician to limit gestational weight gain, and will include a combination of dietary, exercise and behavioural strategies. Women randomised to the Standard Care Group will continue to receive their pregnancy care according to local hospital guidelines, which does not currently include routine provision of dietary, lifestyle and behavioural advice. Outcome assessors will be blinded to the allocated treatment group. Primary Study Outcome: infant large for gestational age (defined as

PATCH: platelet transfusion in cerebral haemorrhage: study protocol for a multicentre, randomised, controlled trial.

PubMed

de Gans, Koen; de Haan, Rob J; Majoie, Charles B; Koopman, Maria M; Brand, Anneke; Dijkgraaf, Marcel G; Vermeulen, Marinus; Roos, Yvo B

2010-03-18

Patients suffering from intracerebral haemorrhage have a poor prognosis, especially if they are using antiplatelet therapy. Currently, no effective acute treatment option for intracerebral haemorrhage exists. Limiting the early growth of intracerebral haemorrhage volume which continues the first hours after admission seems a promising strategy. Because intracerebral haemorrhage patients who are on antiplatelet therapy have been shown to be particularly at risk of early haematoma growth, platelet transfusion may have a beneficial effect. The primary objective is to investigate whether platelet transfusion improves outcome in intracerebral haemorrhage patients who are on antiplatelet treatment. The PATCH study is a prospective, randomised, multi-centre study with open treatment and blind endpoint evaluation. Patients will be randomised to receive platelet transfusion within six hours or standard care. The primary endpoint is functional health after three months. The main secondary endpoints are safety of platelet transfusion and the occurrence of haematoma growth. To detect an absolute poor outcome reduction of 20%, a total of 190 patients will be included. To our knowledge this is the first randomised controlled trial of platelet transfusion for an acute haemorrhagic disease.

Effectiveness of multifaceted educational programme to reduce antibiotic dispensing in primary care: practice based randomised controlled trial

PubMed Central

Simpson, Sharon A; Dunstan, Frank; Rollnick, Stephen; Cohen, David; Gillespie, David; Evans, Meirion R; health, senior lecturer in epidemiology and public; Alam, M Fasihul; Bekkers, Marie-Jet; Evans, John; Moore, Laurence; Howe, Robin; Hayes, Jamie; Hare, Monika; Hood, Kerenza

2012-01-01

Objective To evaluate the effectiveness and costs of a multifaceted flexible educational programme aimed at reducing antibiotic dispensing at the practice level in primary care. Design Randomised controlled trial with general practices as the unit of randomisation and analysis. Clinicians and researchers were blinded to group allocation until after randomisation. Setting 68 general practices with about 480 000 patients in Wales, United Kingdom. Participants 34 practices were randomised to receive the educational programme and 34 practices to be controls. 139 clinicians from the intervention practices and 124 from control practices had agreed to participate before randomisation. Practice level data covering all the clinicians in the 68 practices were analysed. Interventions Intervention practices followed the Stemming the Tide of Antibiotic Resistance (STAR) educational programme, which included a practice based seminar reflecting on the practices’ own dispensing and resistance data, online educational elements, and practising consulting skills in routine care. Control practices provided usual care. Main outcome measures Total numbers of oral antibiotic items dispensed for all causes per 1000 practice patients in the year after the intervention, adjusted for the previous year’s dispensing. Secondary outcomes included reconsultations, admissions to hospital for selected causes, and costs. Results The rate of oral antibiotic dispensing (items per 1000 registered patients) decreased by 14.1 in the intervention group but increased by 12.1 in the control group, a net difference of 26.1. After adjustment for baseline dispensing rate, this amounted to a 4.2% (95% confidence interval 0.6% to 7.7%) reduction in total oral antibiotic dispensing for the year in the intervention group relative to the control group (P=0.02). Reductions were found for all classes of antibiotics other than penicillinase-resistant penicillins but were largest and significant individually for

Robust current control-based generalized predictive control with sliding mode disturbance compensation for PMSM drives.

PubMed

Liu, Xudong; Zhang, Chenghui; Li, Ke; Zhang, Qi

2017-11-01

This paper addresses the current control of permanent magnet synchronous motor (PMSM) for electric drives with model uncertainties and disturbances. A generalized predictive current control method combined with sliding mode disturbance compensation is proposed to satisfy the requirement of fast response and strong robustness. Firstly, according to the generalized predictive control (GPC) theory based on the continuous time model, a predictive current control method is presented without considering the disturbance, which is convenient to be realized in the digital controller. In fact, it's difficult to derive the exact motor model and parameters in the practical system. Thus, a sliding mode disturbance compensation controller is studied to improve the adaptiveness and robustness of the control system. The designed controller attempts to combine the merits of both predictive control and sliding mode control, meanwhile, the controller parameters are easy to be adjusted. Lastly, the proposed controller is tested on an interior PMSM by simulation and experiment, and the results indicate that it has good performance in both current tracking and disturbance rejection. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

How to control if even experts are not sure: Robust fuzzy control

NASA Technical Reports Server (NTRS)

Nguyen, Hung T.; Kreinovich, Vladik YA.; Lea, Robert; Tolbert, Dana

1992-01-01

In real life, the degrees of certainty that correspond to one of the same expert can differ drastically, and fuzzy control algorithms translate these different degrees of uncertainty into different control strategies. In such situations, it is reasonable to choose a fuzzy control methodology that is the least vulnerable to this kind of uncertainty. It is shown that this 'robustness' demand leads to min and max for &- and V-operations, to 1-x for negation, and to centroid as a defuzzification procedure.

Twelve month follow-up on a randomised controlled trial of relaxation training for post-stroke anxiety.

PubMed

Golding, Katherine; Fife-Schaw, Chris; Kneebone, Ian

2017-09-01

To follow up participants in a randomised controlled trial of relaxation training for anxiety after stroke at 12 months. Twelve month follow-up to a randomised controlled trial, in which the control group also received treatment. Community. Fifteen of twenty one original participants with post-stroke anxiety participated in a one year follow-up study. A self-help autogenic relaxation CD listened to five times a week for one month, immediately in the intervention group and after three months in the control group. Hospital Anxiety and Depression Scale-Anxiety subscale and the Telephone Interview of Cognitive Status for inclusion. Hospital Anxiety and Depression Scale-Anxiety subscale for outcome. All measures were administered by phone. Anxiety ratings reduced significantly between pre and post-intervention, and between pre-intervention and one year follow-up ( χ 2 (2) = 22.29, p < 0.001). Reductions in anxiety in stroke survivors who received a self-help autogenic relaxation CD appear to be maintained after one year.

Efficacy of vitamin and antioxidant supplements in prevention of cardiovascular disease: systematic review and meta-analysis of randomised controlled trials

PubMed Central

Ju, Woong; Oh, Seung-Won; Park, Sang Min; Koo, Bon-Kwon; Park, Byung-Joo

2013-01-01

Objective To assess the efficacy of vitamin and antioxidant supplements in the prevention of cardiovascular diseases. Design Meta-analysis of randomised controlled trials. Data sources and study selection PubMed, EMBASE, the Cochrane Library, Scopus, CINAHL, and ClinicalTrials.gov searched in June and November 2012. Two authors independently reviewed and selected eligible randomised controlled trials, based on predetermined selection criteria. Results Out of 2240 articles retrieved from databases and relevant bibliographies, 50 randomised controlled trials with 294 478 participants (156 663 in intervention groups and 137 815 in control groups) were included in the final analyses. In a fixed effect meta-analysis of the 50 trials, supplementation with vitamins and antioxidants was not associated with reductions in the risk of major cardiovascular events (relative risk 1.00, 95% confidence interval 0.98 to 1.02; I2=42%). Overall, there was no beneficial effect of these supplements in the subgroup meta-analyses by type of prevention, type of vitamins and antioxidants, type of cardiovascular outcomes, study design, methodological quality, duration of treatment, funding source, provider of supplements, type of control, number of participants in each trial, and supplements given singly or in combination with other supplements. Among the subgroup meta-analyses by type of cardiovascular outcomes, vitamin and antioxidant supplementation was associated with a marginally increased risk of angina pectoris, while low dose vitamin B6 supplementation was associated with a slightly decreased risk of major cardiovascular events. Those beneficial or harmful effects disappeared in subgroup meta-analysis of high quality randomised controlled trials within each category. Also, even though supplementation with vitamin B6 was associated with a decreased risk of cardiovascular death in high quality trials, and vitamin E supplementation with a decreased risk of myocardial infarction

Robust guaranteed cost tracking control of quadrotor UAV with uncertainties.

PubMed

Xu, Zhiwei; Nian, Xiaohong; Wang, Haibo; Chen, Yinsheng

2017-07-01

In this paper, a robust guaranteed cost controller (RGCC) is proposed for quadrotor UAV system with uncertainties to address set-point tracking problem. A sufficient condition of the existence for RGCC is derived by Lyapunov stability theorem. The designed RGCC not only guarantees the whole closed-loop system asymptotically stable but also makes the quadratic performance level built for the closed-loop system have an upper bound irrespective to all admissible parameter uncertainties. Then, an optimal robust guaranteed cost controller is developed to minimize the upper bound of performance level. Simulation results verify the presented control algorithms possess small overshoot and short setting time, with which the quadrotor has ability to perform set-point tracking task well. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Hysteroscopic resection of a uterine caesarean scar defect (niche) in women with postmenstrual spotting: a randomised controlled trial.

PubMed

Vervoort, Ajmw; van der Voet, L F; Hehenkamp, Wjk; Thurkow, A L; van Kesteren, Pjm; Quartero, H; Kuchenbecker, W; Bongers, M; Geomini, P; de Vleeschouwer, Lhm; van Hooff, Mha; van Vliet, H; Veersema, S; Renes, W B; Oude Rengerink, K; Zwolsman, S E; Brölmann, Ham; Mol, Bwj; Huirne, Jaf

2018-02-01

To compare the effectiveness of a hysteroscopic niche resection versus no treatment in women with postmenstrual spotting and a uterine caesarean scar defect. Multicentre randomised controlled trial. Eleven hospitals collaborating in a consortium for women's health research in the Netherlands. Women reporting postmenstrual spotting after a caesarean section who had a niche with a residual myometrium of ≥3 mm, measured during sonohysterography. Women were randomly allocated to hysteroscopic niche resection or expectant management for 6 months. The primary outcome was the number of days of postmenstrual spotting 6 months after randomisation. Secondary outcomes were spotting at the end of menstruation, intermenstrual spotting, dysuria, sonographic niche measurements, surgical parameters, quality of life, women's satisfaction, sexual function, and additional therapy. Outcomes were measured at 3 months and, except for niche measurements, also at 6 months after randomisation. We randomised 52 women to hysteroscopic niche resection and 51 women to expectant management. The median number of days of postmenstrual spotting at baseline was 8 days in both groups. At 6 months after randomisation, the median number of days of postmenstrual spotting was 4 days (interquartile range, IQR 2-7 days) in the intervention group and 7 days (IQR 3-10 days) in the control group (P = 0.04); on a scale of 0-10, discomfort as a result of spotting had a median score of 2 (IQR 0-7) in the intervention group, compared with 7 (IQR 0-8) in the control group (P = 0.02). In women with a niche with a residual myometrium of ≥3 mm, hysteroscopic niche resection reduced postmenstrual spotting and spotting-related discomfort. A hysteroscopic niche resection is an effective treatment to reduce niche-related spotting. © 2017 The Authors. BJOG An International Journal of Obstetrics and Gynaecology published by John Wiley & Sons Ltd on behalf of Royal College of Obstetricians and Gynaecologists.

Stress in Fathers of Moderately and Late Preterm Infants: A Randomised Controlled Trial

ERIC Educational Resources Information Center

Ravn, Ingrid Helen; Lindemann, Rolf; Smeby, Nina Aarhus; Bunch, Eli Haugen; Sandvik, Leiv; Smith, Lars

2012-01-01

The atypical behaviour of preterm infants can elicit stress in fathers and influence their ability to perceive and interpret infants' cues. This study investigated whether fathers of moderately and late preterm infants were more stressed than fathers of term infants. In a randomised controlled trial, we also studied the effect of the Mother-Infant…

Mitigation of Remedial Action Schemes by Decentralized Robust Governor Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elizondo, Marcelo A.; Marinovici, Laurentiu D.; Lian, Jianming

This paper presents transient stability improvement by a new distributed hierarchical control architecture (DHC). The integration of remedial action schemes (RAS) to the distributed hierarchical control architecture is studied. RAS in power systems are designed to maintain stability and avoid undesired system conditions by rapidly switching equipment and/or changing operating points according to predetermined rules. The acceleration trend relay currently in use in the US western interconnection is an example of RAS that trips generators to maintain transient stability. The link between RAS and DHC is through fast acting robust turbine/governor control that can also improve transient stability. In thismore » paper, the influence of the decentralized robust turbine/governor control on the design of RAS is studied. Benefits of combining these two schemes are increasing power transfer capability and mitigation of RAS generator tripping actions; the later benefit is shown through simulations.« less

A robust control scheme for flexible arms with friction in the joints

NASA Technical Reports Server (NTRS)

Rattan, Kuldip S.; Feliu, Vicente; Brown, H. Benjamin, Jr.

1988-01-01

A general control scheme to control flexible arms with friction in the joints is proposed in this paper. This scheme presents the advantage of being robust in the sense that it minimizes the effects of the Coulomb friction existing in the motor and the effects of changes in the dynamic friction coefficient. A justification of the robustness properties of the scheme is given in terms of the sensitivity analysis.

Robust nonlinear attitude control with disturbance compensation

NASA Astrophysics Data System (ADS)

Walchko, Kevin Jack

Attitude control of small spacecraft is a particularly important component for many missions in the space program: Hubble Space Telescope for observing the cosmos, GPS satellites for navigation, SeaWiFS for studying phytoplankton concentrations in the ocean, etc. Typically designers use proportional derivative control because it is simple to understand and implement. However this method lacks robustness in the presence of disturbances and uncertainties. Thus to improve the fidelity of this simulation, two disturbances were included, fuel slosh and solar snap. Fuel slosh is the unwanted movement of fuel inside of a fuel tank. The fuel slosh model used for the satellite represents each sloshing mode as a mass-spring-damper. The mass represents the wave of fuel that propagates across the tank, the damper represents the baffling that hinders the movement, and the spring represents the force imparted to the spacecraft when the wave impacts the tank wall. This formulation makes the incorporation of multiple modes of interest simple, which is an advance over the typical one sloshing mode, pendulum model. Thermally induce vibrations, or solar snap, occur as a satellite transitions form the day-to-night or night-to-day side of a planet. During this transition, there is a sudden change in the amount of heat flux to the solar panels and vibrations occur. Few authors have looked at the effects of solar snap. The disturbance dynamics were based on the work by Earl Thorten. The simulated effects compared favorably with real flight data taken from satellites that have encountered solar snap. A robust sliding mode controller was developed and compared to a more traditional proportional derivative controller. The controllers were evaluated in the presents of fuel slosh and solar snap. The optimized baseline proportional derivative controller used in this work, showed little effort was needed to obtain better performance using sliding mode. In addition, a colored noise filter was

Robust Neural Sliding Mode Control of Robot Manipulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen Tran Hiep; Pham Thuong Cat

2009-03-05

This paper proposes a robust neural sliding mode control method for robot tracking problem to overcome the noises and large uncertainties in robot dynamics. The Lyapunov direct method has been used to prove the stability of the overall system. Simulation results are given to illustrate the applicability of the proposed method.

Robust H(∞) positional control of 2-DOF robotic arm driven by electro-hydraulic servo system.

PubMed

Guo, Qing; Yu, Tian; Jiang, Dan

2015-11-01

In this paper an H∞ positional feedback controller is developed to improve the robust performance under structural and parametric uncertainty disturbance in electro-hydraulic servo system (EHSS). The robust control model is described as the linear state-space equation by upper linear fractional transformation. According to the solution of H∞ sub-optimal control problem, the robust controller is designed and simplified to lower order linear model which is easily realized in EHSS. The simulation and experimental results can validate the robustness of this proposed method. The comparison result with PI control shows that the robust controller is suitable for this EHSS under the critical condition where the desired system bandwidth is higher and the external load of the hydraulic actuator is closed to its limited capability. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Vaccine testing for emerging infections: the case for individual randomisation

PubMed Central

Eyal, Nir; Lipsitch, Marc

2017-01-01

During the 2014–2015 Ebola outbreak in Guinea, Liberia and Sierra Leone, many opposed the use of individually randomised controlled trials to test candidate Ebola vaccines. For a raging fatal disease, they explained, it is unethical to relegate some study participants to control arms. In Zika and future emerging infections, similar opposition may hinder urgent vaccine research, so it is best to address these questions now. This article lays out the ethical case for individually randomised control in testing vaccines against many emerging infections, including lethal infections in low-income countries, even when at no point in the trial do the controls receive the countermeasures being tested. When individual randomisation is feasible—and it often will be—it tends to save more lives than alternative designs would. And for emerging infections, individual randomisation also tends as such to improve care, access to the experimental vaccine and prospects for all participants relative to their opportunities absent the trial, and no less than alternative designs would. That obtains even under placebo control and without equipoise—requiring which would undermine individual randomisation and the alternative designs that opponents proffered. Our arguments expound four often-neglected factors: benefits to non-participants, benefits to participants once a trial is over including post-trial access to the study intervention, participants’ prospects before randomisation to arms and the near-inevitable disparity between arms in any randomised controlled trial. PMID:28396558

A Scoping Review of Economic Evaluations Alongside Randomised Controlled Trials of Home Monitoring in Chronic Disease Management.

PubMed

Kidholm, Kristian; Kristensen, Mie Borch Dahl

2018-04-01

Many countries have considered telemedicine and home monitoring of patients as a solution to the demographic challenges that health-care systems face. However, reviews of economic evaluations of telemedicine have identified methodological problems in many studies as they do not comply with guidelines. The aim of this study was to examine economic evaluations alongside randomised controlled trials of home monitoring in chronic disease management and hereby to explore the resources included in the programme costs, the types of health-care utilisation that change as a result of home monitoring and discuss the value of economic evaluation alongside randomised controlled trials of home monitoring on the basis of the studies identified. A scoping review of economic evaluations of home monitoring of patients with chronic disease based on randomised controlled trials and including information on the programme costs and the costs of equipment was carried out based on a Medline (PubMed) search. Nine studies met the inclusion criteria. All studies include both costs of equipment and use of staff, but there is large variation in the types of equipment and types of tasks for the staff included in the costs. Equipment costs constituted 16-73% of the total programme costs. In six of the nine studies, home monitoring resulted in a reduction in primary care or emergency contacts. However, in total, home monitoring resulted in increased average costs per patient in six studies and reduced costs in three of the nine studies. The review is limited by the small number of studies found and the restriction to randomised controlled trials, which can be problematic in this area due to lack of blinding of patients and healthcare professionals and the difficulty of implementing organisational changes in hospital departments for the limited period of a trial. Furthermore, our results may be based on assessments of older telemedicine interventions.

Theory of planned behaviour variables and objective walking behaviour do not show seasonal variation in a randomised controlled trial

PubMed Central

2014-01-01

Background Longitudinal studies have shown that objectively measured walking behaviour is subject to seasonal variation, with people walking more in summer compared to winter. Seasonality therefore may have the potential to bias the results of randomised controlled trials if there are not adequate statistical or design controls. Despite this there are no studies that assess the impact of seasonality on walking behaviour in a randomised controlled trial, to quantify the extent of such bias. Further there have been no studies assessing how season impacts on the psychological predictors of walking behaviour to date. The aim of the present study was to assess seasonal differences in a) objective walking behaviour and b) Theory of Planned Behaviour (TPB) variables during a randomised controlled trial of an intervention to promote walking. Methods 315 patients were recruited to a two-arm cluster randomised controlled trial of an intervention to promote walking in primary care. A series of repeated measures ANCOVAs were conducted to examine the effect of season on pedometer measures of walking behaviour and TPB measures, assessed immediately post-intervention and six months later. Hierarchical regression analyses were conducted to assess whether season moderated the prediction of intention and behaviour by TPB measures. Results There were no significant differences in time spent walking in spring/summer compared to autumn/winter. There was no significant seasonal variation in most TPB variables, although the belief that there will be good weather was significantly higher in spring/summer (F = 19.46, p < .001). Season did not significantly predict intention or objective walking behaviour, or moderate the effects of TPB variables on intention or behaviour. Conclusion Seasonality does not influence objectively measured walking behaviour or psychological variables during a randomised controlled trial. Consequently physical activity behaviour outcomes in trials will

Theory of planned behaviour variables and objective walking behaviour do not show seasonal variation in a randomised controlled trial.

PubMed

Williams, Stefanie L; French, David P

2014-02-05

Longitudinal studies have shown that objectively measured walking behaviour is subject to seasonal variation, with people walking more in summer compared to winter. Seasonality therefore may have the potential to bias the results of randomised controlled trials if there are not adequate statistical or design controls. Despite this there are no studies that assess the impact of seasonality on walking behaviour in a randomised controlled trial, to quantify the extent of such bias. Further there have been no studies assessing how season impacts on the psychological predictors of walking behaviour to date. The aim of the present study was to assess seasonal differences in a) objective walking behaviour and b) Theory of Planned Behaviour (TPB) variables during a randomised controlled trial of an intervention to promote walking. 315 patients were recruited to a two-arm cluster randomised controlled trial of an intervention to promote walking in primary care. A series of repeated measures ANCOVAs were conducted to examine the effect of season on pedometer measures of walking behaviour and TPB measures, assessed immediately post-intervention and six months later. Hierarchical regression analyses were conducted to assess whether season moderated the prediction of intention and behaviour by TPB measures. There were no significant differences in time spent walking in spring/summer compared to autumn/winter. There was no significant seasonal variation in most TPB variables, although the belief that there will be good weather was significantly higher in spring/summer (F = 19.46, p < .001). Season did not significantly predict intention or objective walking behaviour, or moderate the effects of TPB variables on intention or behaviour. Seasonality does not influence objectively measured walking behaviour or psychological variables during a randomised controlled trial. Consequently physical activity behaviour outcomes in trials will not be biased by the season in which

Mobile phone SMS messages can enhance healthy behaviour: a meta-analysis of randomised controlled trials.

PubMed

Orr, Jayne A; King, Robert J

2015-01-01

Healthy behaviour, such as smoking cessation and adherence to prescribed medications, mitigates illness risk factors but health behaviour change can be challenging. Mobile phone short-message service (SMS) messages are increasingly used to deliver interventions designed to enhance healthy behaviour. This meta-analysis used a random-effects model to synthesise 38 randomised controlled trials that investigated the efficacy of SMS messages to enhance healthy behaviour. Participants (N = 19,641) lived in developed and developing countries and were diverse with respect to age, ethnicity, socioeconomic background and health behaviours targeted for change. SMS messages had a small, positive, significant effect (g = 0.291) on a broad range of healthy behaviour. This effect was maximised when multiple SMS messages per day were used (g = 0.395) compared to using lower frequencies (daily, multiple per week and once-off) (g = 0.244). The low heterogeneity in this meta-analysis (I (2) = 38.619) supports reporting a summary effect size and implies that the effect of SMS messaging is robust, regardless of population characteristics or healthy behaviour targeted. SMS messaging is a simple, cost-effective intervention that can be automated and can reach any mobile phone owner. While the effect size is small, potential health benefits are well worth achieving.

Robust Economic Control Decision Method of Uncertain System on Urban Domestic Water Supply.

PubMed

Li, Kebai; Ma, Tianyi; Wei, Guo

2018-03-31

As China quickly urbanizes, urban domestic water generally presents the circumstances of both rising tendency and seasonal cycle fluctuation. A robust economic control decision method for dynamic uncertain systems is proposed in this paper. It is developed based on the internal model principle and pole allocation method, and it is applied to an urban domestic water supply system with rising tendency and seasonal cycle fluctuation. To achieve this goal, first a multiplicative model is used to describe the urban domestic water demand. Then, a capital stock and a labor stock are selected as the state vector, and the investment and labor are designed as the control vector. Next, the compensator subsystem is devised in light of the internal model principle. Finally, by using the state feedback control strategy and pole allocation method, the multivariable robust economic control decision method is implemented. The implementation with this model can accomplish the urban domestic water supply control goal, with the robustness for the variation of parameters. The methodology presented in this study may be applied to the water management system in other parts of the world, provided all data used in this study are available. The robust control decision method in this paper is also applicable to deal with tracking control problems as well as stabilization control problems of other general dynamic uncertain systems.

Robust Economic Control Decision Method of Uncertain System on Urban Domestic Water Supply

PubMed Central

Li, Kebai; Ma, Tianyi; Wei, Guo

2018-01-01

As China quickly urbanizes, urban domestic water generally presents the circumstances of both rising tendency and seasonal cycle fluctuation. A robust economic control decision method for dynamic uncertain systems is proposed in this paper. It is developed based on the internal model principle and pole allocation method, and it is applied to an urban domestic water supply system with rising tendency and seasonal cycle fluctuation. To achieve this goal, first a multiplicative model is used to describe the urban domestic water demand. Then, a capital stock and a labor stock are selected as the state vector, and the investment and labor are designed as the control vector. Next, the compensator subsystem is devised in light of the internal model principle. Finally, by using the state feedback control strategy and pole allocation method, the multivariable robust economic control decision method is implemented. The implementation with this model can accomplish the urban domestic water supply control goal, with the robustness for the variation of parameters. The methodology presented in this study may be applied to the water management system in other parts of the world, provided all data used in this study are available. The robust control decision method in this paper is also applicable to deal with tracking control problems as well as stabilization control problems of other general dynamic uncertain systems. PMID:29614749

Management of type 2 diabetes in China: the Happy Life Club, a pragmatic cluster randomised controlled trial using health coaches

PubMed Central

Browning, Colette; Chapman, Anna; Yang, Hui; Liu, Shuo; Zhang, Tuohong; Enticott, Joanne C; Thomas, Shane A

2016-01-01

Objective To assess the effectiveness of a coach-led motivational interviewing (MI) intervention in improving glycaemic control, as well as clinical, psychosocial and self-care outcomes of individuals with type 2 diabetes mellitus (T2DM) compared with usual care. Design Pragmatic cluster randomised controlled trial (RCT). Setting Community Health Stations (CHSs) in Fengtai district, Beijing, China. Participants Of the 41 randomised CHSs (21 intervention and 20 control), 21 intervention CHSs (372 participants) and 18 control CHSs (296 participants) started participation. Intervention Intervention participants received telephone and face-to-face MI health coaching in addition to usual care from their CHS. Control participants received usual care only. Medical fees were waived for both groups. Outcome measures Outcomes were assessed at baseline, 6 and 12 months. Primary outcome measure was glycated haemoglobin (HbA1c). Secondary outcomes included a suite of anthropometric, blood pressure (BP), fasting blood, psychosocial and self-care measures. Results At 12 months, no differential treatment effect was found for HbA1c (adjusted difference 0.02, 95% CI −0.40 to 0.44, p=0.929), with both treatment and control groups showing significant improvements. However, two secondary outcomes: psychological distress (adjusted difference −2.38, 95% CI −4.64 to −0.12, p=0.039) and systolic BP (adjusted difference −3.57, 95% CI −6.08 to −1.05, p=0.005) were robust outcomes consistent with significant differential treatment effects, as supported in sensitivity analyses. Interestingly, in addition to HbA1c, both groups displayed significant improvements in triglycerides, LDL cholesterol and HDL cholesterol. Conclusions In line with the current Chinese primary healthcare reform, this study is the first large-scale cluster RCT to be implemented within real-world CHSs in China, specifically addressing T2DM. Although a differential treatment effect was not observed for Hb

Distribution-dependent robust linear optimization with applications to inventory control

PubMed Central

Kang, Seong-Cheol; Brisimi, Theodora S.

2014-01-01

This paper tackles linear programming problems with data uncertainty and applies it to an important inventory control problem. Each element of the constraint matrix is subject to uncertainty and is modeled as a random variable with a bounded support. The classical robust optimization approach to this problem yields a solution with guaranteed feasibility. As this approach tends to be too conservative when applications can tolerate a small chance of infeasibility, one would be interested in obtaining a less conservative solution with a certain probabilistic guarantee of feasibility. A robust formulation in the literature produces such a solution, but it does not use any distributional information on the uncertain data. In this work, we show that the use of distributional information leads to an equally robust solution (i.e., under the same probabilistic guarantee of feasibility) but with a better objective value. In particular, by exploiting distributional information, we establish stronger upper bounds on the constraint violation probability of a solution. These bounds enable us to “inject” less conservatism into the formulation, which in turn yields a more cost-effective solution (by 50% or more in some numerical instances). To illustrate the effectiveness of our methodology, we consider a discrete-time stochastic inventory control problem with certain quality of service constraints. Numerical tests demonstrate that the use of distributional information in the robust optimization of the inventory control problem results in 36%–54% cost savings, compared to the case where such information is not used. PMID:26347579

Stability and Performance Robustness Assessment of Multivariable Control Systems

DTIC Science & Technology

1993-04-01

00- STABILITY AND PERFORMANCE ROBUSTNESS ASSESSMENT OF MULTIVARIABLE CONTROL SYSTEMS Asok Ray , Jenny I. Shen, and Chen-Kuo Weng Mechanical...Office of Naval Research Assessment of Multivariable Control Systems Grant No. N00014-90-J- 1513 6. AUTHOR(S) (Extension) Professor Asok Ray , Dr...20 The Pennsylvania State University University Park, PA 16802 (20 for Professor Asok Ray ) Naval Postgraduate School

Development and Evaluation of a Pedagogical Tool to Improve Understanding of a Quality Checklist: A Randomised Controlled Trial

PubMed Central

Fourcade, Lola; Boutron, Isabelle; Moher, David; Ronceray, Lucie; Baron, Gabriel; Ravaud, Philippe

2007-01-01

Objective: The aim of this study was to develop and evaluate a pedagogical tool to enhance the understanding of a checklist that evaluates reports of nonpharmacological trials (CLEAR NPT). Design: Paired randomised controlled trial. Participants: Clinicians and systematic reviewers. Interventions: We developed an Internet-based computer learning system (ICLS). This pedagogical tool used many examples from published randomised controlled trials to demonstrate the main coding difficulties encountered when using this checklist. Randomised participants received either a specific Web-based training with the ICLS (intervention group) or no specific training. Outcome measures: The primary outcome was the rate of correct answers compared to a criterion standard for coding a report of randomised controlled trials with the CLEAR NPT. Results: Between April and June 2006, 78 participants were randomly assigned to receive training with the ICLS (39) or no training (39). Participants trained by the ICLS did not differ from the control group in performance on the CLEAR NPT. The mean paired difference and corresponding 95% confidence interval was 0.5 (−5.1 to 6.1). The rate of correct answers did not differ between the two groups regardless of the CLEAR NPT item. Combining both groups, the rate of correct answers was high or items related to allocation sequence (79.5%), description of the intervention (82.0%), blinding of patients (79.5%), and follow-up schedule (83.3%). The rate of correct answers was low for items related to allocation concealment (46.1%), co-interventions (30.3%), blinding of outcome assessors (53.8%), specific measures to avoid ascertainment bias (28.6%), and intention-to-treat analysis (60.2%). Conclusions: Although we showed no difference in effect between the intervention and control groups, our results highlight the gap in knowledge and urgency for education on important aspects of trial conduct. PMID:17479163

Robust control with structured perturbations

NASA Technical Reports Server (NTRS)

Keel, Leehyun

1988-01-01

Two important problems in the area of control systems design and analysis are discussed. The first is the robust stability using characteristic polynomial, which is treated first in characteristic polynomial coefficient space with respect to perturbations in the coefficients of the characteristic polynomial, and then for a control system containing perturbed parameters in the transfer function description of the plant. In coefficient space, a simple expression is first given for the l(sup 2) stability margin for both monic and non-monic cases. Following this, a method is extended to reveal much larger stability region. This result has been extended to the parameter space so that one can determine the stability margin, in terms of ranges of parameter variations, of the closed loop system when the nominal stabilizing controller is given. The stability margin can be enlarged by a choice of better stabilizing controller. The second problem describes the lower order stabilization problem, the motivation of the problem is as follows. Even though the wide range of stabilizing controller design methodologies is available in both the state space and transfer function domains, all of these methods produce unnecessarily high order controllers. In practice, the stabilization is only one of many requirements to be satisfied. Therefore, if the order of a stabilizing controller is excessively high, one can normally expect to have a even higher order controller on the completion of design such as inclusion of dynamic response requirements, etc. Therefore, it is reasonable to have a lowest possible order stabilizing controller first and then adjust the controller to meet additional requirements. The algorithm for designing a lower order stabilizing controller is given. The algorithm does not necessarily produce the minimum order controller; however, the algorithm is theoretically logical and some simulation results show that the algorithm works in general.

Two Reconfigurable Flight-Control Design Methods: Robust Servomechanism and Control Allocation

NASA Technical Reports Server (NTRS)

Burken, John J.; Lu, Ping; Wu, Zheng-Lu; Bahm, Cathy

2001-01-01

Two methods for control system reconfiguration have been investigated. The first method is a robust servomechanism control approach (optimal tracking problem) that is a generalization of the classical proportional-plus-integral control to multiple input-multiple output systems. The second method is a control-allocation approach based on a quadratic programming formulation. A globally convergent fixed-point iteration algorithm has been developed to make onboard implementation of this method feasible. These methods have been applied to reconfigurable entry flight control design for the X-33 vehicle. Examples presented demonstrate simultaneous tracking of angle-of-attack and roll angle commands during failures of the fight body flap actuator. Although simulations demonstrate success of the first method in most cases, the control-allocation method appears to provide uniformly better performance in all cases.

Reading and Language Intervention for Children at Risk of Dyslexia: A Randomised Controlled Trial

ERIC Educational Resources Information Center

Duff, Fiona J.; Hulme, Charles; Grainger, Katy; Hardwick, Samantha J.; Miles, Jeremy N. V.; Snowling, Margaret J.

2014-01-01

Background: Intervention studies for children at risk of dyslexia have typically been delivered preschool, and show short-term effects on letter knowledge and phoneme awareness, with little transfer to literacy. Methods: This randomised controlled trial evaluated the effectiveness of a reading and language intervention for 6-year-old children…

Robust coordinated control of a dual-arm space robot

NASA Astrophysics Data System (ADS)

Shi, Lingling; Kayastha, Sharmila; Katupitiya, Jay

2017-09-01

Dual-arm space robots are more capable of implementing complex space tasks compared with single arm space robots. However, the dynamic coupling between the arms and the base will have a serious impact on the spacecraft attitude and the hand motion of each arm. Instead of considering one arm as the mission arm and the other as the balance arm, in this work two arms of the space robot perform as mission arms aimed at accomplishing secure capture of a floating target. The paper investigates coordinated control of the base's attitude and the arms' motion in the task space in the presence of system uncertainties. Two types of controllers, i.e. a Sliding Mode Controller (SMC) and a nonlinear Model Predictive Controller (MPC) are verified and compared with a conventional Computed-Torque Controller (CTC) through numerical simulations in terms of control accuracy and system robustness. Both controllers eliminate the need to linearly parameterize the dynamic equations. The MPC has been shown to achieve performance with higher accuracy than CTC and SMC in the absence of system uncertainties under the condition that they consume comparable energy. When the system uncertainties are included, SMC and CTC present advantageous robustness than MPC. Specifically, in a case where system inertia increases, SMC delivers higher accuracy than CTC and costs the least amount of energy.

[Pre-randomisation in study designs: getting past the taboo].

PubMed

Schellings, R; Kessels, A G; Sturmans, F

2008-09-20

In October 2006 the Dutch Ministry of Health, Welfare and Sport announced that the use of pre-randomisation in study designs is admissible and not in conflict with the Dutch Medical Research in Human Subjects Act. With pre-randomisation, the conventional sequence of obtaining informed consent followed by randomisation is reversed. According to the original pre-randomisation design (Zelen design), participants are randomised before they are asked to consent; after randomisation, only participants in the experimental group are asked to consent to treatment and effect measurement. In the past, pre-randomisation has seldom been used, and when it was, it was often under the wrong circumstances. Awareness regarding the ethical, legal and methodological objections to pre-randomisation is increasing. About a decade ago, we illustrated the applicability and acceptability of pre-randomisation by means of a fictitious heroin provision trial. In general, pre-randomisation is justified if valid evaluation of the effects of an intervention is impossible using a conventional randomised design, e.g., if knowledge of the intervention may lead to non-compliance or drop-out in the control group, or when the intervention is an educational programme. Other requirements for pre-randomisation include the following: the study has a clinically relevant objective, it is likely that the study will lead to important new insights, the informed consent procedure bears no potential harm to participants, at least standard care is offered to participants in the control group, and the approval of an independent research ethics committee is obtained.

Free breakfasts in schools: design and conduct of a cluster randomised controlled trial of the Primary School Free Breakfast Initiative in Wales [ISRCTN18336527].

PubMed

Moore, Laurence; Moore, Graham F; Tapper, Katy; Lynch, Rebecca; Desousa, Carol; Hale, Janine; Roberts, Chris; Murphy, Simon

2007-09-21

School-based breakfast provision is increasingly being seen as a means of improving educational performance and dietary behaviour amongst children. Furthermore, recognition is growing that breakfast provision offers potential as a means of addressing social inequalities in these outcomes. At present however, the evidence base on the effectiveness of breakfast provision in bringing about these improvements is limited. This paper describes the research design of a large scale evaluation of the effectiveness of the Welsh Assembly Government's Primary School Free Breakfast Initiative. A cluster randomised trial, with school as the unit of randomisation was used for the outcome evaluation, with a nested qualitative process evaluation. Quantitative outcome measures included dietary habits, attitudes, cognitive function, classroom behaviour, and school attendance. The study recruited 111 primary schools in Wales, of which 56 were randomly assigned to control condition and 55 to intervention. Participants were Year 5 and 6 students (aged 9-11 years) in these schools. Data were collected for all 111 schools at each of three time points: baseline, 4 month and 12 month follow-up. This was achieved through a repeated cross-sectional survey of approximately 4350 students on each of these occasions. Of those students in Year 5 at baseline, 1975 provided data at one or both of the follow-ups, forming a nested cohort. The evaluation also included a nested process evaluation, using questionnaires, semi-structured interviews and case studies with students, school staff, and local authority scheme coordinators as key informants. An overview of the methods used for the evaluation is presented, providing an example of the feasibility of conducting robust evaluations of policy initiatives using a randomised trial design with nested process evaluation. Details are provided of response rates and the flow of participants. Reflection is offered on methodological issues encountered at

Randomised controlled trials of veterinary homeopathy: characterising the peer-reviewed research literature for systematic review.

PubMed

Mathie, Robert T; Hacke, Daniela; Clausen, Jürgen

2012-10-01

Systematic review of the research evidence in veterinary homeopathy has never previously been carried out. This paper presents the search methods, together with categorised lists of retrieved records, that enable us to identify the literature that is acceptable for future systematic review of randomised controlled trials (RCTs) in veterinary homeopathy. All randomised and controlled trials of homeopathic intervention (prophylaxis and/or treatment of disease, in any species except man) were appraised according to pre-specified criteria. The following databases were systematically searched from their inception up to and including March 2011: AMED; Carstens-Stiftung Homeopathic Veterinary Clinical Research (HomVetCR) database; CINAHL; Cochrane Central Register of Controlled Trials; Embase; Hom-Inform; LILACS; PubMed; Science Citation Index; Scopus. One hundred and fifty records were retrieved; 38 satisfied the acceptance criteria (substantive report of a clinical treatment or prophylaxis trial in veterinary homeopathic medicine randomised and controlled and published in a peer-reviewed journal), and were thus eligible for future planned systematic review. Approximately half of the rejected records were theses. Seven species and 27 different species-specific medical conditions were represented in the 38 papers. Similar numbers of papers reported trials of treatment and prophylaxis (n=21 and n=17 respectively) and were controlled against placebo or other than placebo (n=18, n=20 respectively). Most research focused on non-individualised homeopathy (n=35 papers) compared with individualised homeopathy (n=3). The results provide a complete and clarified view of the RCT literature in veterinary homeopathy. We will systematically review the 38 substantive peer-reviewed journal articles under the main headings: treatment trials; prophylaxis trials. Copyright © 2012 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.

Randomised controlled trial of amoxycillin clavulanate in children with chronic wet cough.

PubMed

Marchant, Julie; Masters, Ian Brent; Champion, Anita; Petsky, Helen; Chang, Anne B

2012-08-01

Despite guideline recommendations, there are no published randomised controlled trial data on the efficacy of antibiotics for chronic wet cough in children. The majority of children with chronic wet cough have protracted bacterial bronchitis (PBB), a recognised condition in multiple national guidelines. The authors conducted a parallel 1:1 placebo randomised controlled trial to test the hypothesis that a 2-week course of amoxycillin clavulanate is efficacious in the treatment of children with chronic wet cough. 50 children (median age 1.9 years, IQR 0.9-5.1) with chronic (>3 weeks) wet cough were randomised to 2 weeks of twice daily oral amoxycillin clavulanate (22.5 mg/kg/dose) or placebo. The primary outcome was 'cough resolution' defined as a >75% reduction in the validated verbal category descriptive cough score within 14 days of treatment compared with baseline scores, or cessation of cough for >3 days. In selected children, flexible bronchoscopy and bronchoalveolar lavage (BAL) were undertaken at baseline. Cough resolution rates (48%) were significantly higher in children who received amoxycillin clavulanate compared with those who received placebo (16%), p=0.016. The observed difference between proportions was 0.32 (95% CI 0.08 to 0.56). Post treatment, median verbal category descriptive score in the amoxycillin clavulanate group of 0.5 (IQR 0.0-2.0) was significantly lower than in the placebo group, 2.25 (IQR 1.15-2.9) (p=0.02). Pre-treatment BAL data were consistent with PBB in the majority of children, with no significant difference between groups. A 2-week course of amoxycillin clavulanate will achieve cough resolution in a significant number of children with chronic wet cough. BAL data support the diagnosis of PBB in the majority of these children. ACTRN 12605000533695.

Evaluating an extended rehabilitation service for stroke patients (EXTRAS): study protocol for a randomised controlled trial.

PubMed

Rodgers, Helen; Shaw, Lisa; Cant, Robin; Drummond, Avril; Ford, Gary A; Forster, Anne; Hills, Katie; Howel, Denise; Laverty, Anne-Marie; McKevitt, Christopher; McMeekin, Peter; Price, Christopher

2015-05-05

Development of longer term stroke rehabilitation services is limited by lack of evidence of effectiveness for specific interventions and service models. We describe the protocol for a multicentre randomised controlled trial which is evaluating an extended stroke rehabilitation service. The extended service commences when routine 'organised stroke care' (stroke unit and early supported discharge (ESD)) ends. This study is a multicentre randomised controlled trial with health economic and process evaluations. It is set within NHS stroke services which provide ESD. Participants are adults who have experienced a new stroke (and carer if appropriate), discharged from hospital under the care of an ESD team. The intervention group receives an extended stroke rehabilitation service provided for 18 months following completion of ESD. The extended rehabilitation service involves regular contact with a senior ESD team member who leads and coordinates further rehabilitation. Contact is usually by telephone. The control group receives usual stroke care post-ESD. Usual care may involve referral of patients to a range of rehabilitation services upon completion of ESD in accordance with local clinical practice. Randomisation is via a central independent web-based service. The primary outcome is extended activities of daily living (Nottingham Extended Activities of Daily Living Scale) at 24 months post-randomisation. Secondary outcomes (at 12 and 24 months post-randomisation) are health status, quality of life, mood and experience of services for patients, and quality of life, experience of services and carer stress for carers. Resource use and adverse events are also collected. Outcomes are undertaken by a blinded assessor. Implementation and delivery of the extended stroke rehabilitation service will also be described. Semi-structured interviews will be conducted with a subsample of participants and staff to gain insight into perceptions and experiences of rehabilitation services

When is a randomised controlled trial health equity relevant? Development and validation of a conceptual framework.

PubMed

Jull, J; Whitehead, M; Petticrew, M; Kristjansson, E; Gough, D; Petkovic, J; Volmink, J; Weijer, C; Taljaard, M; Edwards, S; Mbuagbaw, L; Cookson, R; McGowan, J; Lyddiatt, A; Boyer, Y; Cuervo, L G; Armstrong, R; White, H; Yoganathan, M; Pantoja, T; Shea, B; Pottie, K; Norheim, O; Baird, S; Robberstad, B; Sommerfelt, H; Asada, Y; Wells, G; Tugwell, P; Welch, V

2017-09-25

Randomised controlled trials can provide evidence relevant to assessing the equity impact of an intervention, but such information is often poorly reported. We describe a conceptual framework to identify health equity-relevant randomised trials with the aim of improving the design and reporting of such trials. An interdisciplinary and international research team engaged in an iterative consensus building process to develop and refine the conceptual framework via face-to-face meetings, teleconferences and email correspondence, including findings from a validation exercise whereby two independent reviewers used the emerging framework to classify a sample of randomised trials. A randomised trial can usefully be classified as 'health equity relevant' if it assesses the effects of an intervention on the health or its determinants of either individuals or a population who experience ill health due to disadvantage defined across one or more social determinants of health. Health equity-relevant randomised trials can either exclusively focus on a single population or collect data potentially useful for assessing differential effects of the intervention across multiple populations experiencing different levels or types of social disadvantage. Trials that are not classified as 'health equity relevant' may nevertheless provide information that is indirectly relevant to assessing equity impact, including information about individual level variation unrelated to social disadvantage and potentially useful in secondary modelling studies. The conceptual framework may be used to design and report randomised trials. The framework could also be used for other study designs to contribute to the evidence base for improved health equity. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Development of robust building energy demand-side control strategy under uncertainty

NASA Astrophysics Data System (ADS)

Kim, Sean Hay

The potential of carbon emission regulations applied to an individual building will encourage building owners to purchase utility-provided green power or to employ onsite renewable energy generation. As both cases are based on intermittent renewable energy sources, demand side control is a fundamental precondition for maximizing the effectiveness of using renewable energy sources. Such control leads to a reduction in peak demand and/or in energy demand variability, therefore, such reduction in the demand profile eventually enhances the efficiency of an erratic supply of renewable energy. The combined operation of active thermal energy storage and passive building thermal mass has shown substantial improvement in demand-side control performance when compared to current state-of-the-art demand-side control measures. Specifically, "model-based" optimal control for this operation has the potential to significantly increase performance and bring economic advantages. However, due to the uncertainty in certain operating conditions in the field its control effectiveness could be diminished and/or seriously damaged, which results in poor performance. This dissertation pursues improvements of current demand-side controls under uncertainty by proposing a robust supervisory demand-side control strategy that is designed to be immune from uncertainty and perform consistently under uncertain conditions. Uniqueness and superiority of the proposed robust demand-side controls are found as below: a. It is developed based on fundamental studies about uncertainty and a systematic approach to uncertainty analysis. b. It reduces variability of performance under varied conditions, and thus avoids the worst case scenario. c. It is reactive in cases of critical "discrepancies" observed caused by the unpredictable uncertainty that typically scenario uncertainty imposes, and thus it increases control efficiency. This is obtainable by means of i) multi-source composition of weather forecasts

Biodegradable stent or balloon dilatation for benign oesophageal stricture: pilot randomised controlled trial.

PubMed

Dhar, Anjan; Close, Helen; Viswanath, Yirupaiahgari K; Rees, Colin J; Hancock, Helen C; Dwarakanath, A Deepak; Maier, Rebecca H; Wilson, Douglas; Mason, James M

2014-12-28

To undertake a randomised pilot study comparing biodegradable stents and endoscopic dilatation in patients with strictures. This British multi-site study recruited seventeen symptomatic adult patients with refractory strictures. Patients were randomised using a multicentre, blinded assessor design, comparing a biodegradable stent (BS) with endoscopic dilatation (ED). The primary endpoint was the average dysphagia score during the first 6 mo. Secondary endpoints included repeat endoscopic procedures, quality of life, and adverse events. Secondary analysis included follow-up to 12 mo. Sensitivity analyses explored alternative estimation methods for dysphagia and multiple imputation of missing values. Nonparametric tests were used. Although both groups improved, the average dysphagia scores for patients receiving stents were higher after 6 mo: BS-ED 1.17 (95%CI: 0.63-1.78) P = 0.029. The finding was robust under different estimation methods. Use of additional endoscopic procedures and quality of life (QALY) estimates were similar for BS and ED patients at 6 and 12 mo. Concomitant use of gastrointestinal prescribed medication was greater in the stent group (BS 5.1, ED 2.0 prescriptions; P < 0.001), as were related adverse events (BS 1.4, ED 0.0 events; P = 0.024). Groups were comparable at baseline and findings were statistically significant but numbers were small due to under-recruitment. The oesophageal tract has somatic sensitivity and the process of the stent dissolving, possibly unevenly, might promote discomfort or reflux. Stenting was associated with greater dysphagia, co-medication and adverse events. Rigorously conducted and adequately powered trials are needed before widespread adoption of this technology.

Robust Stability and Control of Multi-Body Ground Vehicles with Uncertain Dynamics and Failures

DTIC Science & Technology

2010-01-01

and N. Zhang, 2008. “Robust stability control of vehicle rollover subject to actuator time delay”. Proc. IMechE Part I: J. of systems and control ...Dynamic Systems and Control Conference, Boston, MA, Sept 2010 R.K. Yedavalli,”Robust Stability of Linear Interval Parameter Matrix Family Problem...for control coupled output regulation for a class of systems is presented. In section 2.1.7, the control design algorithm developed in section

‘Putting Life in Years’ (PLINY) telephone friendship groups research study: pilot randomised controlled trial

PubMed Central

2014-01-01

Background Loneliness in older people is associated with poor health-related quality of life (HRQoL). We undertook a parallel-group randomised controlled trial to evaluate the effectiveness and cost-effectiveness of telephone befriending for the maintenance of HRQoL in older people. An internal pilot tested the feasibility of the trial and intervention. Methods Participants aged >74 years, with good cognitive function, living independently in one UK city were recruited through general practices and other sources, then randomised to: (1) 6 weeks of short one-to-one telephone calls, followed by 12 weeks of group telephone calls with up to six participants, led by a trained volunteer facilitator; or (2) a control group. The main trial required the recruitment of 248 participants in a 1-year accrual window, of whom 124 were to receive telephone befriending. The pilot specified three success criteria which had to be met in order to progress the main trial to completion: recruitment of 68 participants in 95 days; retention of 80% participants at 6 months; successful delivery of telephone befriending by local franchise of national charity. The primary clinical outcome was the Short Form (36) Health Instrument (SF-36) Mental Health (MH) dimension score collected by telephone 6 months following randomisation. Results We informed 9,579 older people about the study. Seventy consenting participants were randomised to the pilot in 95 days, with 56 (80%) providing valid primary outcome data (26 intervention, 30 control). Twenty-four participants randomly allocated to the research arm actually received telephone befriending due to poor recruitment and retention of volunteer facilitators. The trial was closed early as a result. The mean 6-month SF-36 MH scores were 78 (SD 18) and 71 (SD 21) for the intervention and control groups, respectively (mean difference, 7; 95% CI, -3 to 16). Conclusions Recruitment and retention of participants to a definitive trial with a

Cryotherapy for docetaxel-induced hand and nail toxicity: randomised control trial.

PubMed

McCarthy, Alexandra L; Shaban, Ramon Z; Gillespie, Kerri; Vick, Joanne

2014-05-01

This study investigated the efficacy and safety of cryotherapy, in the form of frozen gel gloves, in relation to docetaxel-induced hand and fingernail toxicities. After piloting with 21 patients, a consecutive series sample of patients (n=53) prescribed docetaxel every 3 weeks, for a minimum of three cycles, was enrolled in this randomised control trial. Participants acted as their own control, with the frozen gel glove worn on one randomised hand for 15 min prior to infusion, for the duration of the infusion, and for 15 min of after completion of treatment. Hand and nail toxicities were evaluated by two blinded assessors according to CTCAE.v4 criteria. To assess the potential for cross-infection of multi-use gloves, microbial culture and sensitivity swabs were taken of each glove at every tenth use. Of the 53 participants enrolled in the main study, 21 provided evaluable data. There was a 60 % withdrawal rate due to patient discomfort with the intervention. The mean incidence and severity of toxicities in all evaluable cycles in control and intervention hands respectively were erythroderma grade 1 (5/5 %), nail discolouration grade 1 (81/67 %), nail loss grade 1 (19/19 %) and nail ridging grade 1 (57/57 %). No significant differences were determined between hand conditions in terms of time to event, nor in terms of toxicity in gloved and non-gloved hands. While cryotherapy in the form of frozen gloves for the cutaneous toxicities associated with docetaxel is safe, its limited efficacy, patient discomfort and some logistical issues preclude its use in our clinical setting.

Tweeting links to Cochrane Schizophrenia Group reviews: a randomised controlled trial.

PubMed

Adams, C E; Jayaram, M; Bodart, A Y M; Sampson, S; Zhao, S; Montgomery, A A

2016-03-08

To assess the effects of using health social media on web activity. Individually randomised controlled parallel group superiority trial. Twitter and Weibo. 170 Cochrane Schizophrenia Group full reviews with an abstract and plain language summary web page. Three randomly ordered slightly different 140 character or less messages, each containing a short URL to the freely accessible summary page sent on specific times on one single day. This was compared with no messaging. The primary outcome was web page visits at 1 week. Secondary outcomes were other metrics of web activity at 1 week. 85 reviews were randomised to each of the intervention and control arms. Google Analytics allowed 100% follow-up within 1 week of completion. Intervention and control reviews received a total of 1162 and 449 visits, respectively (IRR 2.7, 95% CI 2.2 to 3.3). Fewer intervention reviews had single page only visits (16% vs 31%, OR 0.41, 0.19 to 0.88) and users spent more time viewing intervention reviews (geometric mean 76 vs 31 s, ratio 2.5, 1.3 to 4.6). Other secondary metrics of web activity all showed strong evidence in favour of the intervention. Tweeting in this limited area of healthcare increases 'product placement' of evidence with the potential for that to influence care. ISRCTN84658943. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Dental care resistance prevention and antibiotic prescribing modification—the cluster-randomised controlled DREAM trial

PubMed Central

2014-01-01

Background Bacterial resistance development is one of the most urgent problems in healthcare worldwide. In Europe, dentistry accounts for a comparatively high amount of antibiotic prescriptions. In light of increasing levels of bacterial resistance, this development is alarming. So far, very few interventional studies have been performed, and further research is urgently needed. By means of a complex educational intervention, the DREAM trial aims at optimising antibiotic prescribing behaviour of general dentists in Germany. Method This is a cluster-randomised controlled trial, where each cluster consists of one dental practice and all of its patients in a defined period. Participants are general dentists practicing in the German region of Mecklenburg-Western Pomerania. Randomisation takes place after baseline data collection (6 months) and will be stratified by the antibiotic prescribing rates of the participating dental practices. Dentists randomised into the intervention group will participate in a complex small group educational seminar that aims at: increasing knowledge on bacterial resistance, pharmacology, and prophylaxis of infectious endocarditis; increasing awareness of dentist-patient communication using video-taped vignettes of dentist-patient communication on antibiotic treatment; improving collaboration between general dentists, general practitioners, and practice-based cardiologists on the necessity of antibiotic prophylaxis; enhancing awareness of the dentists’ own prescribing habits by providing antibiotic prescribing feedback; and increasing patient knowledge on antibiotic treatment by providing patient-centred information material on antibiotic prophylaxis of endocarditis. The dentists randomised into the control group will not receive any educational programme and provide care as usual. Primary outcome is the overall antibiotic prescribing rate measured at T1 (period of six months after intervention). In a subgroup of adult patients affected

Dental care resistance prevention and antibiotic prescribing modification-the cluster-randomised controlled DREAM trial.

PubMed

Löffler, Christin; Böhmer, Femke; Hornung, Anne; Lang, Hermann; Burmeister, Ulrike; Podbielski, Andreas; Wollny, Anja; Kundt, Günther; Altiner, Attila

2014-02-22

Bacterial resistance development is one of the most urgent problems in healthcare worldwide. In Europe, dentistry accounts for a comparatively high amount of antibiotic prescriptions. In light of increasing levels of bacterial resistance, this development is alarming. So far, very few interventional studies have been performed, and further research is urgently needed. By means of a complex educational intervention, the DREAM trial aims at optimising antibiotic prescribing behaviour of general dentists in Germany. This is a cluster-randomised controlled trial, where each cluster consists of one dental practice and all of its patients in a defined period. Participants are general dentists practicing in the German region of Mecklenburg-Western Pomerania. Randomisation takes place after baseline data collection (6 months) and will be stratified by the antibiotic prescribing rates of the participating dental practices. Dentists randomised into the intervention group will participate in a complex small group educational seminar that aims at: increasing knowledge on bacterial resistance, pharmacology, and prophylaxis of infectious endocarditis; increasing awareness of dentist-patient communication using video-taped vignettes of dentist-patient communication on antibiotic treatment; improving collaboration between general dentists, general practitioners, and practice-based cardiologists on the necessity of antibiotic prophylaxis; enhancing awareness of the dentists' own prescribing habits by providing antibiotic prescribing feedback; and increasing patient knowledge on antibiotic treatment by providing patient-centred information material on antibiotic prophylaxis of endocarditis. The dentists randomised into the control group will not receive any educational programme and provide care as usual. Primary outcome is the overall antibiotic prescribing rate measured at T1 (period of six months after intervention). In a subgroup of adult patients affected by odontogenic

Adjunctive rifampicin to reduce early mortality from Staphylococcus aureus bacteraemia (ARREST): study protocol for a randomised controlled trial

PubMed Central

2012-01-01

Background Staphylococcus aureus bacteraemia is a common and serious infection, with an associated mortality of ~25%. Once in the blood, S. aureus can disseminate to infect almost any organ, but bones, joints and heart valves are most frequently affected. Despite the infection’s severity, the evidence guiding optimal antibiotic therapy is weak: fewer than 1,500 patients have been included in 16 randomised controlled trials investigating S. aureus bacteraemia treatment. It is uncertain which antibiotics are most effective, their route of administration and duration, and whether antibiotic combinations are better than single agents. We hypothesise that adjunctive rifampicin, given in combination with a standard first-line antibiotic, will enhance killing of S. aureus early in the treatment course, sterilise infected foci and blood faster, and thereby reduce the risk of dissemination, metastatic infection and death. Our aim is to determine whether adjunctive rifampicin reduces all-cause mortality within 14 days and bacteriological failure or death within 12 weeks from randomisation. Methods We will perform a parallel group, randomised (1:1), blinded, placebo-controlled trial in NHS hospitals across the UK. Adults (≥18 years) with S. aureus (meticillin-susceptible or resistant) grown from at least one blood culture who have received ≤96 h of active antibiotic therapy for the current infection and do not have contraindications to the use of rifampicin will be eligible for inclusion. Participants will be randomised to adjunctive rifampicin (600-900mg/day; orally or intravenously) or placebo for the first 14 days of therapy in combination with standard single-agent antibiotic therapy. The co-primary outcome measures will be all-cause mortality up to 14 days from randomisation and bacteriological failure/death (all-cause) up to 12 weeks from randomisation. 940 patients will be recruited, providing >80% power to detect 45% and 30% reductions in the two co

Aircraft ride quality controller design using new robust root clustering theory for linear uncertain systems

NASA Technical Reports Server (NTRS)

Yedavalli, R. K.

1992-01-01

The aspect of controller design for improving the ride quality of aircraft in terms of damping ratio and natural frequency specifications on the short period dynamics is addressed. The controller is designed to be robust with respect to uncertainties in the real parameters of the control design model such as uncertainties in the dimensional stability derivatives, imperfections in actuator/sensor locations and possibly variations in flight conditions, etc. The design is based on a new robust root clustering theory developed by the author by extending the nominal root clustering theory of Gutman and Jury to perturbed matrices. The proposed methodology allows to get an explicit relationship between the parameters of the root clustering region and the uncertainty radius of the parameter space. The current literature available for robust stability becomes a special case of this unified theory. The bounds derived on the parameter perturbation for robust root clustering are then used in selecting the robust controller.

Review of Randomised Controlled Trials of Internet Interventions for Mental Disorders and Related Conditions

ERIC Educational Resources Information Center

Griffiths, Kathleen M.; Christensen, Helen

2006-01-01

Self-help Internet interventions have the potential to enable consumers to play a central role in managing their own health. This paper contains a systematic review of 15 randomised controlled trials of the effectiveness of self-help Internet interventions for mental disorders and related conditions. Conditions addressed by the interventions…

Vaccine testing for emerging infections: the case for individual randomisation.

PubMed

Eyal, Nir; Lipsitch, Marc

2017-09-01

During the 2014-2015 Ebola outbreak in Guinea, Liberia and Sierra Leone, many opposed the use of individually randomised controlled trials to test candidate Ebola vaccines. For a raging fatal disease, they explained, it is unethical to relegate some study participants to control arms. In Zika and future emerging infections, similar opposition may hinder urgent vaccine research, so it is best to address these questions now. This article lays out the ethical case for individually randomised control in testing vaccines against many emerging infections, including lethal infections in low-income countries, even when at no point in the trial do the controls receive the countermeasures being tested. When individual randomisation is feasible-and it often will be-it tends to save more lives than alternative designs would. And for emerging infections, individual randomisation also tends as such to improve care, access to the experimental vaccine and prospects for all participants relative to their opportunities absent the trial, and no less than alternative designs would. That obtains even under placebo control and without equipoise-requiring which would undermine individual randomisation and the alternative designs that opponents proffered. Our arguments expound four often-neglected factors: benefits to non-participants, benefits to participants once a trial is over including post-trial access to the study intervention, participants' prospects before randomisation to arms and the near-inevitable disparity between arms in any randomised controlled trial. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Social Dancing and Incidence of Falls in Older Adults: A Cluster Randomised Controlled Trial

PubMed Central

Merom, Dafna; Mathieu, Erin; Cerin, Ester; Morton, Rachael L.; Simpson, Judy M.; Anstey, Kaarin J.; Sherrington, Catherine; Lord, Stephen R.; Cumming, Robert G.

2016-01-01

Background The prevention of falls among older people is a major public health challenge. Exercises that challenge balance are recognized as an efficacious fall prevention strategy. Given that small-scale trials have indicated that diverse dance styles can improve balance and gait of older adults, two of the strongest risk factors for falls in older people, this study aimed to determine whether social dance is effective in i) reducing the number of falls and ii) improving physical and cognitive fall-related risk factors. Methods and Findings A parallel two-arm cluster randomized controlled trial was undertaken in 23 self-care retirement villages (clusters) around Sydney, Australia. Eligible villages had to have an appropriate hall for dancing, house at least 60 residents, and not be currently offering dance as a village activity. Retirement villages were randomised using a computer generated randomisation method, constrained using minimisation. Eligible participants had to be a resident of the village, be able to walk at least 50 m, and agree to undergo physical and cognitive testing without cognitive impairment. Residents of intervention villages (12 clusters) were offered twice weekly one-hour social dancing classes (folk or ballroom dancing) over 12 mo (80 h in total). Programs were standardized across villages and were delivered by eight dance teachers. Participants in the control villages (11 clusters) were advised to continue with their regular activities. Main outcomes: falls during the 12 mo trial and Trail Making Tests. Secondary outcomes: The Physiological Performance Assessment (i.e., postural sway, proprioception, reaction time, leg strength) and the Short Physical Performance Battery; health-related physical and mental quality of life from the Short-Form 12 (SF-12) Survey. Data on falls were obtained from 522 of 530 (98%) randomised participants (mean age 78 y, 85% women) and 424 (80%) attended the 12-mo reassessment, which was lower among folk dance

Social Dancing and Incidence of Falls in Older Adults: A Cluster Randomised Controlled Trial.

PubMed

Merom, Dafna; Mathieu, Erin; Cerin, Ester; Morton, Rachael L; Simpson, Judy M; Rissel, Chris; Anstey, Kaarin J; Sherrington, Catherine; Lord, Stephen R; Cumming, Robert G

2016-08-01

The prevention of falls among older people is a major public health challenge. Exercises that challenge balance are recognized as an efficacious fall prevention strategy. Given that small-scale trials have indicated that diverse dance styles can improve balance and gait of older adults, two of the strongest risk factors for falls in older people, this study aimed to determine whether social dance is effective in i) reducing the number of falls and ii) improving physical and cognitive fall-related risk factors. A parallel two-arm cluster randomized controlled trial was undertaken in 23 self-care retirement villages (clusters) around Sydney, Australia. Eligible villages had to have an appropriate hall for dancing, house at least 60 residents, and not be currently offering dance as a village activity. Retirement villages were randomised using a computer generated randomisation method, constrained using minimisation. Eligible participants had to be a resident of the village, be able to walk at least 50 m, and agree to undergo physical and cognitive testing without cognitive impairment. Residents of intervention villages (12 clusters) were offered twice weekly one-hour social dancing classes (folk or ballroom dancing) over 12 mo (80 h in total). Programs were standardized across villages and were delivered by eight dance teachers. Participants in the control villages (11 clusters) were advised to continue with their regular activities. falls during the 12 mo trial and Trail Making Tests. The Physiological Performance Assessment (i.e., postural sway, proprioception, reaction time, leg strength) and the Short Physical Performance Battery; health-related physical and mental quality of life from the Short-Form 12 (SF-12) Survey. Data on falls were obtained from 522 of 530 (98%) randomised participants (mean age 78 y, 85% women) and 424 (80%) attended the 12-mo reassessment, which was lower among folk dance participants (71%) than ballroom dancing (82%) or control

Nonlinear robust controller design for multi-robot systems with unknown payloads

NASA Technical Reports Server (NTRS)

Song, Y. D.; Anderson, J. N.; Homaifar, A.; Lai, H. Y.

1992-01-01

This work is concerned with the control problem of a multi-robot system handling a payload with unknown mass properties. Force constraints at the grasp points are considered. Robust control schemes are proposed that cope with the model uncertainty and achieve asymptotic path tracking. To deal with the force constraints, a strategy for optimally sharing the task is suggested. This strategy basically consists of two steps. The first detects the robots that need help and the second arranges that help. It is shown that the overall system is not only robust to uncertain payload parameters, but also satisfies the force constraints.

Cervicovestibular rehabilitation in sport-related concussion: a randomised controlled trial.

PubMed

Schneider, Kathryn J; Meeuwisse, Willem H; Nettel-Aguirre, Alberto; Barlow, Karen; Boyd, Lara; Kang, Jian; Emery, Carolyn A

2014-09-01

Concussion is a common injury in sport. Most individuals recover in 7-10 days but some have persistent symptoms. The objective of this study was to determine if a combination of vestibular rehabilitation and cervical spine physiotherapy decreased the time until medical clearance in individuals with prolonged postconcussion symptoms. This study was a randomised controlled trial. Consecutive patients with persistent symptoms of dizziness, neck pain and/or headaches following a sport-related concussion (12-30 years, 18 male and 13 female) were randomised to the control or intervention group. Both groups received weekly sessions with a physiotherapist for 8 weeks or until the time of medical clearance. Both groups received postural education, range of motion exercises and cognitive and physical rest until asymptomatic followed by a protocol of graded exertion. The intervention group also received cervical spine and vestibular rehabilitation. The primary outcome of interest was medical clearance to return to sport, which was evaluated by a study sport medicine physician who was blinded to the treatment group. In the treatment group, 73% (11/15) of the participants were medically cleared within 8 weeks of initiation of treatment, compared with 7% (1/14) in the control group. Using an intention to treat analysis, individuals in the treatment group were 3.91 (95% CI 1.34 to 11.34) times more likely to be medically cleared by 8 weeks. A combination of cervical and vestibular physiotherapy decreased time to medical clearance to return to sport in youth and young adults with persistent symptoms of dizziness, neck pain and/or headaches following a sport-related concussion. NCT01860755. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

A clinical and economic evaluation of Control of Hyperglycaemia in Paediatric intensive care (CHiP): a randomised controlled trial.

PubMed

Macrae, Duncan; Grieve, Richard; Allen, Elizabeth; Sadique, Zia; Betts, Helen; Morris, Kevin; Pappachan, Vithayathil John; Parslow, Roger; Tasker, Robert C; Baines, Paul; Broadhead, Michael; Duthie, Mark L; Fortune, Peter-Marc; Inwald, David; McMaster, Paddy; Peters, Mark J; Schindler, Margrid; Guerriero, Carla; Piercy, Deborah; Slavik, Zdenek; Snowdon, Claire; Van Dyck, Laura; Elbourne, Diana

2014-04-01

Early research in adults admitted to intensive care suggested that tight control of blood glucose during acute illness can be associated with reductions in mortality, length of hospital stay and complications such as infection and renal failure. Prior to our study, it was unclear whether or not children could also benefit from tight control of blood glucose during critical illness. This study aimed to determine if controlling blood glucose using insulin in paediatric intensive care units (PICUs) reduces mortality and morbidity and is cost-effective, whether or not admission follows cardiac surgery. Randomised open two-arm parallel group superiority design with central randomisation with minimisation. Analysis was on an intention-to-treat basis. Following random allocation, care givers and outcome assessors were no longer blind to allocation. The setting was 13 English PICUs. Patients who met the following criteria were eligible for inclusion: ≥ 36 weeks corrected gestational age; ≤ 16 years; in the PICU following injury, following major surgery or with critical illness; anticipated treatment > 12 hours; arterial line; mechanical ventilation; and vasoactive drugs. Exclusion criteria were as follows: diabetes mellitus; inborn error of metabolism; treatment withdrawal considered; in the PICU > 5 consecutive days; and already in CHiP (Control of Hyperglycaemia in Paediatric intensive care). The intervention was tight glycaemic control (TGC): insulin by intravenous infusion titrated to maintain blood glucose between 4.0 and 7.0 mmol/l. This consisted of insulin by intravenous infusion only if blood glucose exceeded 12.0 mmol/l on two samples at least 30 minutes apart; insulin was stopped when blood glucose fell below 10.0 mmol/l. The primary outcome was the number of days alive and free from mechanical ventilation within 30 days of trial entry (VFD-30). The secondary outcomes comprised clinical and economic outcomes at 30 days and 12 months and

Individualised pelvic floor muscle training in women with pelvic organ prolapse (POPPY): a multicentre randomised controlled trial.

PubMed

Hagen, Suzanne; Stark, Diane; Glazener, Cathryn; Dickson, Sylvia; Barry, Sarah; Elders, Andrew; Frawley, Helena; Galea, Mary P; Logan, Janet; McDonald, Alison; McPherson, Gladys; Moore, Kate H; Norrie, John; Walker, Andrew; Wilson, Don

2014-03-01

Pelvic organ prolapse is common and is strongly associated with childbirth and increasing age. Women with prolapse are often advised to do pelvic floor muscle exercises, but evidence supporting the benefits of such exercises is scarce. We aimed to establish the effectiveness of one-to-one individualised pelvic floor muscle training for reducing prolapse symptoms. We did a parallel-group, multicentre, randomised controlled trial at 23 centres in the UK, one in New Zealand, and one in Australia, between June 22, 2007, and April 9, 2010. Female outpatients with newly-diagnosed, symptomatic stage I, II, or III prolapse were randomly assigned (1:1), by remote computer allocation with minimsation, to receive an individualised programme of pelvic floor muscle training or a prolapse lifestyle advice leaflet and no muscle training (control group). Outcome assessors, and investigators who were gynaecologists at trial sites, were masked to group allocation; the statistician was masked until after data analysis. Our primary endpoint was participants' self-report of prolapse symptoms at 12 months. Analysis was by intention-to-treat analysis. This trial is registered, number ISRCTN35911035. 447 eligible patients were randomised to the intervention group (n=225) or the control group (n=222). 377 (84%) participants completed follow-up for questionnaires at 6 months and 295 (66%) for questionnaires at 12 months. Women in the intervention group reported fewer prolapse symptoms (ie, a significantly greater reduction in the pelvic organ prolapse symptom score [POP-SS]) at 12 months than those in the control group (mean reduction in POP-SS from baseline 3.77 [SD 5.62] vs 2.09 [5.39]; adjusted difference 1.52, 95% CI 0.46-2.59; p=0.0053). Findings were robust to missing data. Eight adverse events (six vaginal symptoms, one case of back pain, and one case of abdominal pain) and one unexpected serious adverse event, all in women from the intervention group, were regarded as unrelated to

Timing of birth for women with a twin pregnancy at term: a randomised controlled trial

PubMed Central

2010-01-01

randomised trial, the findings of which will contribute information about the optimal time of birth for women with an uncomplicated multiple pregnancy at and beyond 37 weeks gestation. Clinical Trial Registration Current Controlled Trials ISRCTN15761056 PMID:20973989

Goal-orientated cognitive rehabilitation for dementias associated with Parkinson's disease-A pilot randomised controlled trial.

PubMed

Hindle, John V; Watermeyer, Tamlyn J; Roberts, Julie; Brand, Andrew; Hoare, Zoe; Martyr, Anthony; Clare, Linda

2018-05-01

To examine the appropriateness and feasibility of cognitive rehabilitation for people with dementias associated with Parkinson's in a pilot randomised controlled study. This was a single-blind pilot randomised controlled trial of goal-oriented cognitive rehabilitation for dementias associated with Parkinson's. After goal setting, participants were randomised to cognitive rehabilitation (n = 10), relaxation therapy (n = 10), or treatment-as-usual (n = 9). Primary outcomes were ratings of goal attainment and satisfaction with goal attainment. Secondary outcomes included quality of life, mood, cognition, health status, everyday functioning, and carers' ratings of goal attainment and their own quality of life and stress levels. Assessments were at 2 and 6 months following randomisation. At 2 months, cognitive rehabilitation was superior to treatment-as-usual and relaxation therapy for the primary outcomes of self-rated goal attainment (d = 1.63 and d = 1.82, respectively) and self-rated satisfaction with goal attainment (d = 2.04 and d = 1.84). At 6 months, cognitive rehabilitation remained superior to treatment-as-usual (d = 1.36) and relaxation therapy (d = 1.77) for self-rated goal attainment. Cognitive rehabilitation was superior to treatment as usual and/or relaxation therapy in a number of secondary outcomes at 2 months (mood, self-efficacy, social domain of quality of life, carers' ratings of participants' goal attainment) and at 6 months (delayed recall, health status, quality of life, carer ratings of participants' goal attainment). Carers receiving cognitive rehabilitation reported better quality of life, health status, and lower stress than those allocated to treatment-as-usual. Cognitive rehabilitation is feasible and potentially effective for dementias associated with Parkinson's disease. Copyright © 2018 John Wiley & Sons, Ltd.

Intelligence and Persisting with Medication for Two Years: Analysis in a Randomised Controlled Trial

ERIC Educational Resources Information Center

Deary, Ian J.; Gale, Catharine R.; Stewart, Marlene C. W.; Fowkes, F. Gerald R.; Murray, Gordon D.; Batty, G. David; Price, Jacqueline F.

2009-01-01

The study examined whether verbal intelligence is associated with persisting to take medication for up to two years. The design is a prospective follow-up of compliance with taking medication in high-risk individuals participating in a randomised, placebo-controlled trial set in Central Scotland. Participants were 1993 people aged between 50 and…

Sport-specific biomechanical responses to an ACL injury prevention programme: A randomised controlled trial.

PubMed

Taylor, Jeffrey B; Ford, Kevin R; Schmitz, Randy J; Ross, Scott E; Ackerman, Terry A; Shultz, Sandra J

2018-04-19

Anterior cruciate ligament (ACL) injury prevention programmes have not been as successful at reducing injury rates in women's basketball as in soccer. This randomised controlled trial (ClinicalTrials.gov #NCT02530333) compared biomechanical adaptations in basketball and soccer players during jump-landing activities after an ACL injury prevention programme. Eighty-seven athletes were cluster randomised into intervention (6-week programme) and control groups. Three-dimensional biomechanical analyses of drop vertical jump (DVJ), double- (SAG-DL) and single-leg (SAG-SL) sagittal, and double- (FRONT-DL) and single-leg (FRONT-SL) frontal plane jump landing tasks were tested before and after the intervention. Peak angles, excursions, and joint moments were analysed using two-way MANCOVAs of post-test scores while controlling for pre-test scores. During SAG-SL the basketball intervention group exhibited increased peak knee abduction angles (p = .004) and excursions (p = .003) compared to the basketball control group (p = .01) and soccer intervention group (p = .01). During FRONT-SL, the basketball intervention group exhibited greater knee flexion excursion after training than the control group (p = .01), but not the soccer intervention group (p = .11). Although women's soccer players exhibit greater improvements in knee abduction kinematics than basketball players, these athletes largely exhibit similar biomechanical adaptations to ACL injury prevention programmes.

A new look at the robust control of discrete-time Markov jump linear systems

NASA Astrophysics Data System (ADS)

Todorov, M. G.; Fragoso, M. D.

2016-03-01

In this paper, we make a foray in the role played by a set of four operators on the study of robust H2 and mixed H2/H∞ control problems for discrete-time Markov jump linear systems. These operators appear in the study of mean square stability for this class of systems. By means of new linear matrix inequality (LMI) characterisations of controllers, which include slack variables that, to some extent, separate the robustness and performance objectives, we introduce four alternative approaches to the design of controllers which are robustly stabilising and at the same time provide a guaranteed level of H2 performance. Since each operator provides a different degree of conservatism, the results are unified in the form of an iterative LMI technique for designing robust H2 controllers, whose convergence is attained in a finite number of steps. The method yields a new way of computing mixed H2/H∞ controllers, whose conservatism decreases with iteration. Two numerical examples illustrate the applicability of the proposed results for the control of a small unmanned aerial vehicle, and for an underactuated robotic arm.

Can Healthcare Assistant Training (CHAT) improve the relational care of older people? Study protocol for a pilot cluster randomised controlled trial.

PubMed

Arthur, Antony; Maben, Jill; Wharrad, Heather; Aldus, Clare; Sarre, Sophie; Schneider, Justine; Nicholson, Caroline; Barton, Garry; Cox, Karen; Clark, Allan

2015-12-09

People aged 75 years and over account for 1 in 4 of all hospital admissions. There has been increasing recognition of problems in the care of older people, particularly in hospitals. Evidence suggests that older people judge the care they receive in terms of kindness, empathy, compassion, respectful communication and being seen as a person not just a patient. These are aspects of care to which we refer when we use the term 'relational care'. Healthcare assistants deliver an increasing proportion of direct care to older people, yet their training needs are often overlooked. This study will determine the acceptability and feasibility of a cluster randomised controlled trial of 'Older People's Shoes' a 2-day training intervention for healthcare assistants caring for older people in hospital. Within this pilot, 2-arm, parallel, cluster randomised controlled trial, healthcare assistants within acute hospital wards are randomised to either the 2-day training intervention or training as usual. Registered nurses deliver 'Older People's Shoes' over 2 days, approximately 1 week apart. It contains three components: experiential learning about ageing, exploration of older people's stories, and customer care. Outcomes will be measured at the level of patient (experience of emotional care and quality of life during their hospital stay), healthcare assistant (empathy and attitudes towards older people), and ward (quality of staff/patient interaction). Semi-structured interviews of a purposive sample of healthcare assistants receiving the intervention, and all trainers delivering the intervention, will be undertaken to gain insights into the experiences of both the intervention and the trial, and its perceived impact on practice. Few training interventions for care staff have been rigorously tested using randomised designs. This study will establish the viability of a definitive cluster randomised controlled trial of a new training intervention to improve the relational care

Promoting Recruitment using Information Management Efficiently (PRIME): study protocol for a stepped-wedge cluster randomised controlled trial within the REstart or STop Antithrombotics Randomised Trial (RESTART).

PubMed

Maxwell, Amy E; Dennis, Martin; Rudd, Anthony; Weir, Christopher J; Parker, Richard A; Al-Shahi Salman, Rustam

2017-03-01

Research into methods to boost recruitment has been identified as the highest priority for randomised controlled trial (RCT) methodological research in the United Kingdom. Slow recruitment delays the delivery of research and inflates costs. Using electronic patient records has been shown to boost recruitment to ongoing RCTs in primary care by identifying potentially eligible participants, but this approach remains relatively unexplored in secondary care, and for stroke in particular. The REstart or STop Antithrombotics Randomised Trial (RESTART; ISRCTN71907627) is an ongoing RCT of secondary prevention after stroke due to intracerebral haemorrhage. Promoting Recruitment using Information Management Efficiently (PRIME) is a stepped-wedge cluster randomised trial of a complex intervention to help RESTART sites increase their recruitment and attain their own target numbers of participants. Seventy-two hospital sites that were located in England, Wales or Scotland and were active in RESTART in June 2015 opted into PRIME. Sites were randomly allocated (using a computer-generated block randomisation algorithm, stratified by hospital location in Scotland vs. England/Wales) to one of 12 months in which the intervention would be delivered. All sites began in the control state. The intervention was delivered by a recruitment co-ordinator via a teleconference with each site. The intervention involved discussing recruitment strategies, providing software for each site to extract from their own stroke audit data lists of patients who were potentially eligible for RESTART, and a second teleconference to review progress 6 months later. The recruitment co-ordinator was blinded to the timing of the intervention until 2 months before it was due at a site. Staff at RESTART sites were blinded to the nature and timing of the intervention. The primary outcome is the total number of patients randomised into RESTART per month per site and will be analysed in a negative binomial

Immediate chest X-ray for patients at risk of lung cancer presenting in primary care: randomised controlled feasibility trial

PubMed Central

Neal, Richard D; Barham, Allan; Bongard, Emily; Edwards, Rhiannon Tudor; Fitzgibbon, Jim; Griffiths, Gareth; Hamilton, Willie; Hood, Kerenza; Nelson, Annmarie; Parker, David; Porter, Cath; Prout, Hayley; Roberts, Kirsty; Rogers, Trevor; Thomas-Jones, Emma; Tod, Angela; Yeo, Seow Tien; Hurt, Chris N

2017-01-01

Background: Achieving earlier stage diagnosis is one option for improving lung cancer outcomes in the United Kingdom. Patients with lung cancer typically present with symptoms to general practitioners several times before referral or investigation. Methods: We undertook a mixed methods feasibility individually randomised controlled trial (the ELCID trial) to assess the feasibility and inform the design of a definitive, fully powered, UK-wide, Phase III trial of lowering the threshold for urgent investigation of suspected lung cancer. Patients over 60, with a smoking history, presenting with new chest symptoms to primary care, were eligible to be randomised to intervention (urgent chest X-ray) or usual care. Results: The trial design and materials were acceptable to GPs and patients. We randomised 255 patients from 22 practices, although the proportion of eligible patients who participated was lower than expected. Survey responses (89%), and the fidelity of the intervention (82% patients X-rayed within 3 weeks) were good. There was slightly higher anxiety and depression in the control arm in participants aged >75. Three patients (1.2%) were diagnosed with lung cancer. Conclusions: We have demonstrated the feasibility of individually randomising patients at higher risk of lung cancer, to a trial offering urgent investigation or usual care. PMID:28072761

Social Stories in mainstream schools for children with autism spectrum disorder: a feasibility randomised controlled trial.

PubMed

Marshall, David; Wright, Barry; Allgar, Victoria; Adamson, Joy; Williams, Christine; Ainsworth, Hannah; Cook, Liz; Varley, Danielle; Hackney, Lisa; Dempster, Paul; Ali, Shehzad; Trepel, Dominic; Collingridge Moore, Danielle; Littlewood, Elizabeth; McMillan, Dean

2016-08-11

To assess the feasibility of recruitment, retention, outcome measures and intervention training/delivery among teachers, parents and children. To calculate a sample size estimation for full trial. A single-centre, unblinded, cluster feasibility randomised controlled trial examining Social Stories delivered within a school environment compared with an attentional control. 37 primary schools in York, UK. 50 participants were recruited and a cluster randomisation approach by school was examined. Participants were randomised into the treatment group (n=23) or a waiting list control group (n=27). Acceptability and feasibility of the trial, intervention and of measurements required to assess outcomes in a definitive trial. An assessment of the questionnaire completion rates indicated teachers would be most appropriate to complete the primary outcome measure. 2 outcome measures: the Social Responsiveness Scale (SRS)-2 and a goal-based measure showed both the highest levels of completion rates (above 80%) at the primary follow-up point (6 weeks postintervention) and captured relevant social and behaviour outcomes. Power calculations were based on these 2 outcome measures leading to a total proposed sample size of 180 participant groups. Results suggest that a future trial would be feasible to conduct and could inform the policy and practice of using Social Stories in mainstream schools. ISRCTN96286707; Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Robust fractional order sliding mode control of doubly-fed induction generator (DFIG)-based wind turbines.

PubMed

Ebrahimkhani, Sadegh

2016-07-01

Wind power plants have nonlinear dynamics and contain many uncertainties such as unknown nonlinear disturbances and parameter uncertainties. Thus, it is a difficult task to design a robust reliable controller for this system. This paper proposes a novel robust fractional-order sliding mode (FOSM) controller for maximum power point tracking (MPPT) control of doubly fed induction generator (DFIG)-based wind energy conversion system. In order to enhance the robustness of the control system, uncertainties and disturbances are estimated using a fractional order uncertainty estimator. In the proposed method a continuous control strategy is developed to achieve the chattering free fractional order sliding-mode control, and also no knowledge of the uncertainties and disturbances or their bound is assumed. The boundedness and convergence properties of the closed-loop signals are proven using Lyapunov׳s stability theory. Simulation results in the presence of various uncertainties were carried out to evaluate the effectiveness and robustness of the proposed control scheme. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Parametric robust control and system identification: Unified approach

NASA Technical Reports Server (NTRS)

Keel, Leehyun

1994-01-01

Despite significant advancement in the area of robust parametric control, the problem of synthesizing such a controller is still a wide open problem. Thus, we attempt to give a solution to this important problem. Our approach captures the parametric uncertainty as an H(sub infinity) unstructured uncertainty so that H(sub infinity) synthesis techniques are applicable. Although the techniques cannot cope with the exact parametric uncertainty, they give a reasonable guideline to model the unstructured uncertainty that contains the parametric uncertainty. An additional loop shaping technique is also introduced to relax its conservatism.

The effects of enteral feeding improvement massage on premature infants: A randomised controlled trial.

PubMed

Kim, Hee-Young; Bang, Kyung-Sook

2018-01-01

To prove the effects of an enteral feeding improvement massage for premature infants with regard to their feeding, growing and superior mesentery artery blood flow aspect by a randomised controlled trial. Premature infants have feeding-related problems related to eating and absorbing nutrition due to their immature gastrointestinal function. Studies regarding the effectiveness of premature infants' enteral feeding improvement by tactile stimulation massage are rare. The study group was composed of 55 patients. Of the 55 patients, 26 were randomised into an experimental group and 29 were randomised into a control group. They were all born <34 weeks of gestational age between 1 July 2011 and 30 March 2012. Premature infants in the experimental group received enteral feeding improvement massage twice a day for 14 days, and infants in the control group received a sham exercise. The collected data were analysed by spss 19.0, through t test, chi-square test (Fisher's exact) and ANCOVA. (i) The experimental group had reached the day of full enteral feeding significantly faster. (ii) The experimental group had a higher superior mesentery artery peak velocity (V max ) and lower RI (resistant index). (iii) The experimental group of the feeding-intolerant subgroup had a higher superior mesentery artery V max and V min . (iv) The experimental group had a heavier weight and larger head circumference after 14 days. This study demonstrates that enteral feeding improvement massage can be helpful for achieving earlier full enteral feeding, more increased superior mesentery artery, and faster growing. In particular, it can be a therapeutic, independent and evidence-based nursing intervention for feeding-intolerant premature infants. Neonatal nurses in neonatal intensive care unit can apply enteral feeding improvement massage massage for feeding-intolerant infants. © 2017 John Wiley & Sons Ltd.

An adaptive robust controller for time delay maglev transportation systems

NASA Astrophysics Data System (ADS)

Milani, Reza Hamidi; Zarabadipour, Hassan; Shahnazi, Reza

2012-12-01

For engineering systems, uncertainties and time delays are two important issues that must be considered in control design. Uncertainties are often encountered in various dynamical systems due to modeling errors, measurement noises, linearization and approximations. Time delays have always been among the most difficult problems encountered in process control. In practical applications of feedback control, time delay arises frequently and can severely degrade closed-loop system performance and in some cases, drives the system to instability. Therefore, stability analysis and controller synthesis for uncertain nonlinear time-delay systems are important both in theory and in practice and many analytical techniques have been developed using delay-dependent Lyapunov function. In the past decade the magnetic and levitation (maglev) transportation system as a new system with high functionality has been the focus of numerous studies. However, maglev transportation systems are highly nonlinear and thus designing controller for those are challenging. The main topic of this paper is to design an adaptive robust controller for maglev transportation systems with time-delay, parametric uncertainties and external disturbances. In this paper, an adaptive robust control (ARC) is designed for this purpose. It should be noted that the adaptive gain is derived from Lyapunov-Krasovskii synthesis method, therefore asymptotic stability is guaranteed.

Vibrating vaginal balls to improve pelvic floor muscle performance in women after childbirth: a protocol for a randomised controlled feasibility trial.

PubMed

Oblasser, Claudia; McCourt, Christine; Hanzal, Engelbert; Christie, Janice

2016-04-01

This paper presents a feasibility trial protocol the purpose of which is to prepare for a future randomised controlled trial to determine the effectiveness of vibrating vaginal pelvic floor training balls for postpartum pelvic floor muscle rehabilitation. Vibrating vaginal pelvic floor training balls are available in Austria to enhance women's pelvic floor muscles and thus prevent or treat urinary incontinence and other pelvic floor problems following childbirth. Nonetheless, there is currently little empirical knowledge to substantiate their use or assess their relative effectiveness in comparison to current standard care, which involves pelvic floor muscle exercises. Single blind, randomised controlled feasibility trial with two parallel groups. It is planned to recruit 56 postpartum women in Vienna, who will be randomised into one of two intervention groups to use either vibrating vaginal balls or a comparator pelvic floor muscle exercises for 12 weeks. As this is a feasibility study, study design features (recruitment, selection, randomisation, intervention concordance, data collection methods and tools) will be assessed and participants' views and experiences will be surveyed. Tested outcome measures, collected before and after the intervention, will be pelvic floor muscle performance as reported by participants and measured by perineometry. Descriptive and inferential statistics and content analysis will serve the preparation of the future trial. The results of this feasibility trial will inform the design and conduct of a full randomised controlled trial and provide insight into the experiences of women regarding the interventions and study participation. © 2015 John Wiley & Sons Ltd.

Robust Control Algorithm for a Two Cart System and an Inverted Pendulum

NASA Technical Reports Server (NTRS)

Wilson, Chris L.; Capo-Lugo, Pedro

2011-01-01

The Rectilinear Control System can be used to simulate a launch vehicle during liftoff. Several control schemes have been developed that can control different dynamic models of the rectilinear plant. A robust control algorithm was developed that can control a pendulum to maintain an inverted position. A fluid slosh tank will be attached to the pendulum in order to test robustness in the presence of unknown slosh characteristics. The rectilinear plant consists of a DC motor and three carts mounted in series. Each cart s weight can be adjusted with brass masses and the carts can be coupled with springs. The pendulum is mounted on the first cart and an adjustable air damper can be attached to the third cart if desired. Each cart and the pendulum have a quadrature encoder to determine position. Full state feedback was implemented in order to develop the control algorithm along with a state estimator to determine the velocity states of the system. A MATLAB program was used to convert the state space matrices from continuous time to discrete time. This program also used a desired phase margin and damping ratio to determine the feedback gain matrix that would be used in the LabVIEW program. This experiment will allow engineers to gain a better understanding of liquid propellant slosh dynamics, therefore enabling them to develop more robust control algorithms for launch vehicle systems

Robust algebraic image enhancement for intelligent control systems

NASA Technical Reports Server (NTRS)

Lerner, Bao-Ting; Morrelli, Michael

1993-01-01

Robust vision capability for intelligent control systems has been an elusive goal in image processing. The computationally intensive techniques a necessary for conventional image processing make real-time applications, such as object tracking and collision avoidance difficult. In order to endow an intelligent control system with the needed vision robustness, an adequate image enhancement subsystem capable of compensating for the wide variety of real-world degradations, must exist between the image capturing and the object recognition subsystems. This enhancement stage must be adaptive and must operate with consistency in the presence of both statistical and shape-based noise. To deal with this problem, we have developed an innovative algebraic approach which provides a sound mathematical framework for image representation and manipulation. Our image model provides a natural platform from which to pursue dynamic scene analysis, and its incorporation into a vision system would serve as the front-end to an intelligent control system. We have developed a unique polynomial representation of gray level imagery and applied this representation to develop polynomial operators on complex gray level scenes. This approach is highly advantageous since polynomials can be manipulated very easily, and are readily understood, thus providing a very convenient environment for image processing. Our model presents a highly structured and compact algebraic representation of grey-level images which can be viewed as fuzzy sets.

Robust Feedback Control of Flow Induced Structural Radiation of Sound

NASA Technical Reports Server (NTRS)

Heatwole, Craig M.; Bernhard, Robert J.; Franchek, Matthew A.

1997-01-01

A significant component of the interior noise of aircraft and automobiles is a result of turbulent boundary layer excitation of the vehicular structure. In this work, active robust feedback control of the noise due to this non-predictable excitation is investigated. Both an analytical model and experimental investigations are used to determine the characteristics of the flow induced structural sound radiation problem. The problem is shown to be broadband in nature with large system uncertainties associated with the various operating conditions. Furthermore the delay associated with sound propagation is shown to restrict the use of microphone feedback. The state of the art control methodologies, IL synthesis and adaptive feedback control, are evaluated and shown to have limited success for solving this problem. A robust frequency domain controller design methodology is developed for the problem of sound radiated from turbulent flow driven plates. The control design methodology uses frequency domain sequential loop shaping techniques. System uncertainty, sound pressure level reduction performance, and actuator constraints are included in the design process. Using this design method, phase lag was added using non-minimum phase zeros such that the beneficial plant dynamics could be used. This general control approach has application to lightly damped vibration and sound radiation problems where there are high bandwidth control objectives requiring a low controller DC gain and controller order.

Screening versus routine practice in detection of atrial fibrillation in patients aged 65 or over: cluster randomised controlled trial

PubMed Central

Fitzmaurice, David A; Jowett, Sue; Mant, Jonathon; Murray, Ellen T; Holder, Roger; Raftery, J P; Bryan, S; Davies, Michael; Lip, Gregory Y H; Allan, T F

2007-01-01

Objectives To assess whether screening improves the detection of atrial fibrillation (cluster randomisation) and to compare systematic and opportunistic screening. Design Multicentred cluster randomised controlled trial, with subsidiary trial embedded within the intervention arm. Setting 50 primary care centres in England, with further individual randomisation of patients in the intervention practices. Participants 14 802 patients aged 65 or over in 25 intervention and 25 control practices. Interventions Patients in intervention practices were randomly allocated to systematic screening (invitation for electrocardiography) or opportunistic screening (pulse taking and invitation for electrocardiography if the pulse was irregular). Screening took place over 12 months in each practice from October 2001 to February 2003. No active screening took place in control practices. Main outcome measure Newly identified atrial fibrillation. Results The detection rate of new cases of atrial fibrillation was 1.63% a year in the intervention practices and 1.04% in control practices (difference 0.59%, 95% confidence interval 0.20% to 0.98%). Systematic and opportunistic screening detected similar numbers of new cases (1.62% v 1.64%, difference 0.02%, −0.5% to 0.5%). Conclusion Active screening for atrial fibrillation detects additional cases over current practice. The preferred method of screening in patients aged 65 or over in primary care is opportunistic pulse taking with follow-up electrocardiography. Trial registration Current Controlled Trials ISRCTN19633732. PMID:17673732

Robot Assisted Training for the Upper Limb after Stroke (RATULS): study protocol for a randomised controlled trial.

PubMed

Rodgers, Helen; Shaw, Lisa; Bosomworth, Helen; Aird, Lydia; Alvarado, Natasha; Andole, Sreeman; Cohen, David L; Dawson, Jesse; Eyre, Janet; Finch, Tracy; Ford, Gary A; Hislop, Jennifer; Hogg, Steven; Howel, Denise; Hughes, Niall; Krebs, Hermano Igo; Price, Christopher; Rochester, Lynn; Stamp, Elaine; Ternent, Laura; Turner, Duncan; Vale, Luke; Warburton, Elizabeth; van Wijck, Frederike; Wilkes, Scott

2017-07-20

Loss of arm function is a common and distressing consequence of stroke. We describe the protocol for a pragmatic, multicentre randomised controlled trial to determine whether robot-assisted training improves upper limb function following stroke. Study design: a pragmatic, three-arm, multicentre randomised controlled trial, economic analysis and process evaluation. NHS stroke services. adults with acute or chronic first-ever stroke (1 week to 5 years post stroke) causing moderate to severe upper limb functional limitation. Randomisation groups: 1. Robot-assisted training using the InMotion robotic gym system for 45 min, three times/week for 12 weeks 2. Enhanced upper limb therapy for 45 min, three times/week for 12 weeks 3. Usual NHS care in accordance with local clinical practice Randomisation: individual participant randomisation stratified by centre, time since stroke, and severity of upper limb impairment. upper limb function measured by the Action Research Arm Test (ARAT) at 3 months post randomisation. upper limb impairment (Fugl-Meyer Test), activities of daily living (Barthel ADL Index), quality of life (Stroke Impact Scale, EQ-5D-5L), resource use, cost per quality-adjusted life year and adverse events, at 3 and 6 months. Blinding: outcomes are undertaken by blinded assessors. Economic analysis: micro-costing and economic evaluation of interventions compared to usual NHS care. A within-trial analysis, with an economic model will be used to extrapolate longer-term costs and outcomes. Process evaluation: semi-structured interviews with participants and professionals to seek their views and experiences of the rehabilitation that they have received or provided, and factors affecting the implementation of the trial. allowing for 10% attrition, 720 participants provide 80% power to detect a 15% difference in successful outcome between each of the treatment pairs. Successful outcome definition: baseline ARAT 0-7 must improve by 3 or more points; baseline

Supplemental parenteral nutrition in critically ill patients: a study protocol for a phase II randomised controlled trial.

PubMed

Ridley, Emma J; Davies, Andrew R; Parke, Rachael; Bailey, Michael; McArthur, Colin; Gillanders, Lyn; Cooper, David J; McGuinness, Shay

2015-12-24

Nutrition is one of the fundamentals of care provided to critically ill adults. The volume of enteral nutrition received, however, is often much less than prescribed due to multiple functional and process issues. To deliver the prescribed volume and correct the energy deficit associated with enteral nutrition alone, parenteral nutrition can be used in combination (termed "supplemental parenteral nutrition"), but benefits of this method have not been firmly established. A multi-centre, randomised, clinical trial is currently underway to determine if prescribed energy requirements can be provided to critically ill patients by using a supplemental parenteral nutrition strategy in the critically ill. This prospective, multi-centre, randomised, stratified, parallel-group, controlled, phase II trial aims to determine whether a supplemental parenteral nutrition strategy will reliably and safely increase energy intake when compared to usual care. The study will be conducted for 100 critically ill adults with at least one organ system failure and evidence of insufficient enteral intake from six intensive care units in Australia and New Zealand. Enrolled patients will be allocated to either a supplemental parenteral nutrition strategy for 7 days post randomisation or to usual care with enteral nutrition. The primary outcome will be the average energy amount delivered from nutrition therapy over the first 7 days of the study period. Secondary outcomes include protein delivery for 7 days post randomisation; total energy and protein delivery, antibiotic use and organ failure rates (up to 28 days); duration of ventilation, length of intensive care unit and hospital stay. At both intensive care unit and hospital discharge strength and health-related quality of life assessments will be undertaken. Study participants will be followed up for health-related quality of life, resource utilisation and survival at 90 and 180 days post randomisation (unless death occurs first). This trial

Medical expulsive therapy in adults with ureteric colic: a multicentre, randomised, placebo-controlled trial.

PubMed

Pickard, Robert; Starr, Kathryn; MacLennan, Graeme; Lam, Thomas; Thomas, Ruth; Burr, Jennifer; McPherson, Gladys; McDonald, Alison; Anson, Kenneth; N'Dow, James; Burgess, Neil; Clark, Terry; Kilonzo, Mary; Gillies, Katie; Shearer, Kirsty; Boachie, Charles; Cameron, Sarah; Norrie, John; McClinton, Samuel

2015-07-25

Meta-analyses of previous randomised controlled trials concluded that the smooth muscle relaxant drugs tamsulosin and nifedipine assisted stone passage for people managed expectantly for ureteric colic, but emphasised the need for high-quality trials with wide inclusion criteria. We aimed to fulfil this need by testing effectiveness of these drugs in a standard clinical care setting. For this multicentre, randomised, placebo-controlled trial, we recruited adults (aged 18-65 years) undergoing expectant management for a single ureteric stone identified by CT at 24 UK hospitals. Participants were randomly assigned by a remote randomisation system to tamsulosin 400 μg, nifedipine 30 mg, or placebo taken daily for up to 4 weeks, using an algorithm with centre, stone size (≤5 mm or >5 mm), and stone location (upper, mid, or lower ureter) as minimisation covariates. Participants, clinicians, and trial personnel were masked to treatment assignment. The primary outcome was the proportion of participants who did not need further intervention for stone clearance within 4 weeks of randomisation, analysed in a modified intention-to-treat population defined as all eligible patients for whom we had primary outcome data. This trial is registered with the European Clinical Trials Database, EudraCT number 2010-019469-26, and as an International Standard Randomised Controlled Trial, number 69423238. Between Jan 11, 2011, and Dec 20, 2013, we randomly assigned 1167 participants, 1136 (97%) of whom were included in the primary analysis (17 were excluded because of ineligibility and 14 participants were lost to follow-up). 303 (80%) of 379 participants in the placebo group did not need further intervention by 4 weeks, compared with 307 (81%) of 378 in the tamsulosin group (adjusted risk difference 1·3% [95% CI -5·7 to 8·3]; p=0·73) and 304 (80%) of 379 in the nifedipine group (0·5% [-5·6 to 6·5]; p=0·88). No difference was noted between active treatment and placebo (p=0·78

A Comprehensive Robust Adaptive Controller for Gust Load Alleviation

PubMed Central

Quagliotti, Fulvia

2014-01-01

The objective of this paper is the implementation and validation of an adaptive controller for aircraft gust load alleviation. The contribution of this paper is the design of a robust controller that guarantees the reduction of the gust loads, even when the nominal conditions change. Some preliminary results are presented, considering the symmetric aileron deflection as control device. The proposed approach is validated on subsonic transport aircraft for different mass and flight conditions. Moreover, if the controller parameters are tuned for a specific gust model, even if the gust frequency changes, no parameter retuning is required. PMID:24688411

Interactive web-based pulmonary rehabilitation programme: a randomised controlled feasibility trial

PubMed Central

Chaplin, Emma; Hewitt, Stacey; Apps, Lindsay; Bankart, John; Pulikottil-Jacob, Ruth; Boyce, Sally; Morgan, Mike; Williams, Johanna; Singh, Sally

2017-01-01

Objectives The aim of this study was to determine if an interactive web-based pulmonary rehabilitation (PR) programme is a feasible alternative to conventional PR. Design Randomised controlled feasibility trial. Setting Participants with a diagnosis of chronic obstructive pulmonary disease were recruited from PR assessments, primary care and community rehabilitation programmes. Patients randomised to conventional rehabilitation started the programme according to the standard care at their referred site on the next available date. Participants 103 patients were recruited to the study and randomised: 52 to conventional rehabilitation (mean (±SD) age 66 (±8) years, Medical Research Council (MRC) 3 (IQR2–4)); 51 to the web arm (mean (±SD) age 66 (±10) years, MRC 3 (IQR2–4)). Participants had to be willing to participate in either arm of the trial, have internet access and be web literate. Interventions Patients randomised to the web-based programme worked through the website, exercising and recording their progress as well as reading educational material. Conventional PR consisted of twice weekly, 2 hourly sessions (an hour for exercise training and an hour for education). Outcome measures Recruitment rates, eligibility, patient preference and dropout and completion rates for both programmes were collected. Standard outcomes for a PR assessment including measures of exercise capacity and quality of life questionnaires were also evaluated. Results A statistically significant improvement (p≤0.01) was observed within each group in the endurance shuttle walk test (WEB: mean change 189±211.1; PR classes: mean change 184.5±247.4 s) and Chronic Respiratory disease Questionnaire-Dyspnoea (CRQ-D; WEB: mean change 0.7±1.2; PR classes: mean change 0.8±1.0). However, there were no significant differences between the groups in any outcome. Dropout rates were higher in the web-based programme (57% vs 23%). Conclusions An interactive web-based PR programme is feasible

Interactive web-based pulmonary rehabilitation programme: a randomised controlled feasibility trial.

PubMed

Chaplin, Emma; Hewitt, Stacey; Apps, Lindsay; Bankart, John; Pulikottil-Jacob, Ruth; Boyce, Sally; Morgan, Mike; Williams, Johanna; Singh, Sally

2017-03-31

The aim of this study was to determine if an interactive web-based pulmonary rehabilitation (PR) programme is a feasible alternative to conventional PR. Randomised controlled feasibility trial. Participants with a diagnosis of chronic obstructive pulmonary disease were recruited from PR assessments, primary care and community rehabilitation programmes. Patients randomised to conventional rehabilitation started the programme according to the standard care at their referred site on the next available date. 103 patients were recruited to the study and randomised: 52 to conventional rehabilitation (mean (±SD) age 66 (±8) years, Medical Research Council (MRC) 3 (IQR2-4)); 51 to the web arm (mean (±SD) age 66 (±10) years, MRC 3 (IQR2-4)). Participants had to be willing to participate in either arm of the trial, have internet access and be web literate. Patients randomised to the web-based programme worked through the website, exercising and recording their progress as well as reading educational material. Conventional PR consisted of twice weekly, 2 hourly sessions (an hour for exercise training and an hour for education). Recruitment rates, eligibility, patient preference and dropout and completion rates for both programmes were collected. Standard outcomes for a PR assessment including measures of exercise capacity and quality of life questionnaires were also evaluated. A statistically significant improvement (p≤0.01) was observed within each group in the endurance shuttle walk test (WEB: mean change 189±211.1; PR classes: mean change 184.5±247.4 s) and Chronic Respiratory disease Questionnaire-Dyspnoea (CRQ-D; WEB: mean change 0.7±1.2; PR classes: mean change 0.8±1.0). However, there were no significant differences between the groups in any outcome. Dropout rates were higher in the web-based programme (57% vs 23%). An interactive web-based PR programme is feasible and acceptable when compared with conventional PR. Future trials maybe around choice-based PR

Robust nonlinear variable selective control for networked systems

NASA Astrophysics Data System (ADS)

Rahmani, Behrooz

2016-10-01

This paper is concerned with the networked control of a class of uncertain nonlinear systems. In this way, Takagi-Sugeno (T-S) fuzzy modelling is used to extend the previously proposed variable selective control (VSC) methodology to nonlinear systems. This extension is based upon the decomposition of the nonlinear system to a set of fuzzy-blended locally linearised subsystems and further application of the VSC methodology to each subsystem. To increase the applicability of the T-S approach for uncertain nonlinear networked control systems, this study considers the asynchronous premise variables in the plant and the controller, and then introduces a robust stability analysis and control synthesis. The resulting optimal switching-fuzzy controller provides a minimum guaranteed cost on an H2 performance index. Simulation studies on three nonlinear benchmark problems demonstrate the effectiveness of the proposed method.

Acupuncture and Counselling for Depression in Primary Care: A Randomised Controlled Trial

PubMed Central

MacPherson, Hugh; Richmond, Stewart; Bland, Martin; Brealey, Stephen; Gabe, Rhian; Hopton, Ann; Keding, Ada; Lansdown, Harriet; Perren, Sara; Sculpher, Mark; Spackman, Eldon; Torgerson, David; Watt, Ian

2013-01-01

Background Depression is a significant cause of morbidity. Many patients have communicated an interest in non-pharmacological therapies to their general practitioners. Systematic reviews of acupuncture and counselling for depression in primary care have identified limited evidence. The aim of this study was to evaluate acupuncture versus usual care and counselling versus usual care for patients who continue to experience depression in primary care. Methods and Findings In a randomised controlled trial, 755 patients with depression (Beck Depression Inventory BDI-II score ≥20) were recruited from 27 primary care practices in the North of England. Patients were randomised to one of three arms using a ratio of 2∶2∶1 to acupuncture (302), counselling (302), and usual care alone (151). The primary outcome was the difference in mean Patient Health Questionnaire (PHQ-9) scores at 3 months with secondary analyses over 12 months follow-up. Analysis was by intention-to-treat. PHQ-9 data were available for 614 patients at 3 months and 572 patients at 12 months. Patients attended a mean of ten sessions for acupuncture and nine sessions for counselling. Compared to usual care, there was a statistically significant reduction in mean PHQ-9 depression scores at 3 months for acupuncture (−2.46, 95% CI −3.72 to −1.21) and counselling (−1.73, 95% CI −3.00 to −0.45), and over 12 months for acupuncture (−1.55, 95% CI −2.41 to −0.70) and counselling (−1.50, 95% CI −2.43 to −0.58). Differences between acupuncture and counselling were not significant. In terms of limitations, the trial was not designed to separate out specific from non-specific effects. No serious treatment-related adverse events were reported. Conclusions In this randomised controlled trial of acupuncture and counselling for patients presenting with depression, after having consulted their general practitioner in primary care, both interventions were associated with significantly reduced

Study protocol of a multicentre randomised controlled trial of self-help cognitive behaviour therapy for working women with menopausal symptoms (MENOS@Work).

PubMed

Hunter, Myra S; Hardy, Claire; Norton, Sam; Griffiths, Amanda

2016-10-01

Hot flushes and night sweats (HFNS) - the main symptoms of the menopause transition - can reduce quality of life and are particularly difficult to manage at work. A cognitive behaviour therapy (CBT) intervention has been developed specifically for HFNS that is theoretically based and shown to reduce significantly the impact of HFNS in several randomised controlled trials (RCTs). Self-help CBT has been found to be as effective as group CBT for these symptoms, but these interventions are not widely available in the workplace. This paper describes the protocol of an RCT aiming to assess the efficacy of CBT for menopausal symptoms implemented in the workplace, with a nested qualitative study to examine acceptability and feasibility. One hundred menopausal working women, aged 45-60 years, experiencing bothersome HFNS for two months will be recruited from several (2-10) large organisations into a multicentre randomised controlled trial. Women will be randomly assigned to either treatment (a self-help CBT intervention lasting 4 weeks) or to a no treatment-wait control condition (NTWC), following a screening interview, consent, and completion of a baseline questionnaire. All participants will complete follow-up questionnaires at 6 weeks and 20 weeks post-randomisation. The primary outcome is the rating of HFNS; secondary measures include HFNS frequency, mood, quality of life, attitudes to menopause, HFNS beliefs and behaviours, work absence and presenteeism, job satisfaction, job stress, job performance, disclosure to managers and turnover intention. Adherence, acceptability and feasibility will be assessed at 20 weeks post-randomisation in questionnaires and qualitative interviews. Upon trial completion, the control group will also be offered the intervention. This is the first randomised controlled trial of a self-management intervention tailored for working women who have troublesome menopausal symptoms. Clin.Gov NCT02623374. Copyright © 2016 Elsevier Ireland Ltd. All

Thermal clothing to reduce heart failure morbidity during winter: a randomised controlled trial

PubMed Central

Stewart, Ian; Beevers, Andrea; Fraser, John F; Platts, David

2017-01-01

Objective To examine whether providing thermal clothing improved the health of patients with heart failure during winter. Design Parallel group randomised controlled trial. Setting Large public hospital in Brisbane during winter 2016. Participants 91 patients with systolic or diastolic heart failure who were over 50 years old. Intervention 47 patients were randomised to receive thermal clothes (socks, top and hat) and 44 received usual care. Patients could not be blinded to their randomised group. All patients’ data were available for the primary outcome which was collected blind to randomised group. Main outcome measures The primary outcome was the mean number of days in hospital during winter. Secondary outcomes included quality of life and sleep, and blood tests were collected for cardiovascular risk factors. Participants completed clothing diaries in midwinter which were used to estimate their overall clothing insulation using the ‘clo’. Monitors inside the participants’ homes recorded indoor temperatures throughout winter. Results The mean number of days in hospital during winter was 4.2 in the usual care group and 3.0 in the thermal clothing group (mean difference –1.2 days, 95% CI –4.8 to 2.5 days). Most participants (85%) in the thermal clothing group reported using the thermals. There was an increase in overall clothing insulation at night in the thermal clothing group (mean difference 0.13 clo, 95% CI 0.03 to 0.23). Most participants in both groups did not wear sufficient clothing (defined as a clo below 1) and regularly experienced indoor temperatures below 18°C during midwinter. Conclusions There was no clear statistical improvement in health in the thermal clothing group. Efforts to improve health during winter may need to focus on passive interventions such as home insulation rather than interventions that target behaviour change. Trial registration number ACTRN12615001023549; Results. PMID:28993390

Biodegradable stent or balloon dilatation for benign oesophageal stricture: Pilot randomised controlled trial

PubMed Central

Dhar, Anjan; Close, Helen; Viswanath, Yirupaiahgari K; Rees, Colin J; Hancock, Helen C; Dwarakanath, A Deepak; Maier, Rebecca H; Wilson, Douglas; Mason, James M

2014-01-01

AIM: To undertake a randomised pilot study comparing biodegradable stents and endoscopic dilatation in patients with strictures. METHODS: This British multi-site study recruited seventeen symptomatic adult patients with refractory strictures. Patients were randomised using a multicentre, blinded assessor design, comparing a biodegradable stent (BS) with endoscopic dilatation (ED). The primary endpoint was the average dysphagia score during the first 6 mo. Secondary endpoints included repeat endoscopic procedures, quality of life, and adverse events. Secondary analysis included follow-up to 12 mo. Sensitivity analyses explored alternative estimation methods for dysphagia and multiple imputation of missing values. Nonparametric tests were used. RESULTS: Although both groups improved, the average dysphagia scores for patients receiving stents were higher after 6 mo: BS-ED 1.17 (95%CI: 0.63-1.78) P = 0.029. The finding was robust under different estimation methods. Use of additional endoscopic procedures and quality of life (QALY) estimates were similar for BS and ED patients at 6 and 12 mo. Concomitant use of gastrointestinal prescribed medication was greater in the stent group (BS 5.1, ED 2.0 prescriptions; P < 0.001), as were related adverse events (BS 1.4, ED 0.0 events; P = 0.024). Groups were comparable at baseline and findings were statistically significant but numbers were small due to under-recruitment. The oesophageal tract has somatic sensitivity and the process of the stent dissolving, possibly unevenly, might promote discomfort or reflux. CONCLUSION: Stenting was associated with greater dysphagia, co-medication and adverse events. Rigorously conducted and adequately powered trials are needed before widespread adoption of this technology. PMID:25561787

Robust decentralized control laws for the ACES structure

NASA Technical Reports Server (NTRS)

Collins, Emmanuel G., Jr.; Phillips, Douglas J.; Hyland, David C.

1991-01-01

Control system design for the Active Control Technique Evaluation for Spacecraft (ACES) structure at NASA Marshall Space Flight Center is discussed. The primary objective of this experiment is to design controllers that provide substantial reduction of the line-of-sight pointing errors. Satisfaction of this objective requires the controllers to attenuate beam vibration significantly. The primary method chosen for control design is the optimal projection approach for uncertain systems (OPUS). The OPUS design process allows the simultaneous tradeoff of five fundamental issues in control design: actuator sizing, sensor accuracy, controller order, robustness, and system performance. A brief description of the basic ACES configuration is given. The development of the models used for control design and control design for eight system loops that were selected by analysis of test data collected from the structure are discussed. Experimental results showing that very significant performance improvement is achieved when all eight feedback loops are closed are presented.

Physical ACtivity facilitation for Elders (PACE): study protocol for a randomised controlled trial.

PubMed

Morgan, Gemma S; Haase, Anne M; Campbell, Rona; Ben-Shlomo, Yoav

2015-03-13

As people live longer, their risk of disability increases. Disability affects quality of life and increases health and social care costs. Preventing or delaying disability is therefore an important objective, and identifying an effective intervention could improve the lives of many older people. Observational and interventional evidence suggests that physical activity may reduce the risk of age-related disability, as assessed by physical performance measures. However it is unclear what approach is the most cost-effective intervention in changing long-term physical activity behaviour in older adults. A new theory-driven behavioural intervention has been developed, with the aim of increasing physical activity in the everyday lives of older adults at risk of disability. This pilot study tests the feasibility and acceptability of delivering this intervention to older adults. A randomised controlled trial (RCT) design will be used in the pilot study. Sixty patients aged 65 years and older will be recruited from primary care practices. Patients will be eligible to participate if they are inactive, not disabled at baseline, are at risk of developing disability in the future (Short Physical Performance Battery score <10/12), and have no contraindications to physical activity. Following baseline measures, participants will be randomised in a 2:1 ratio to the intervention or to a control arm and all participants will be followed-up after 6 months. Those randomised to the intervention arm will receive sessions with a trained Physical Activity Facilitator, delivering an intervention based on self-determination theory. Control participants receive a booklet on healthy ageing. The main outcomes of interest are recruitment, adherence, retention and acceptability. Data will also be collected on: self-report and accelerometer-recorded physical activity; physical performance; depression; wellbeing; cognitive function; social support; quality of life, healthcare use, and attitudes to

Continuous versus intermittent endotracheal cuff pressure control for the prevention of ventilator-associated respiratory infections in Vietnam: study protocol for a randomised controlled trial.

PubMed

Dat, Vu Quoc; Geskus, Ronald B; Wolbers, Marcel; Loan, Huynh Thi; Yen, Lam Minh; Binh, Nguyen Thien; Chien, Le Thanh; Mai, Nguyen Thi Hoang; Phu, Nguyen Hoan; Lan, Nguyen Phu Huong; Hao, Nguyen Van; Long, Hoang Bao; Thuy, Tran Phuong; Kinh, Nguyen Van; Trung, Nguyen Vu; Phu, Vu Dinh; Cap, Nguyen Trung; Trinh, Dao Tuyet; Campbell, James; Kestelyn, Evelyne; Wertheim, Heiman F L; Wyncoll, Duncan; Thwaites, Guy Edward; van Doorn, H Rogier; Thwaites, C Louise; Nadjm, Behzad

2018-04-04

Ventilator-associated respiratory infection (VARI) comprises ventilator-associated pneumonia (VAP) and ventilator-associated tracheobronchitis (VAT). Although their diagnostic criteria vary, together these are the most common hospital-acquired infections in intensive care units (ICUs) worldwide, responsible for a large proportion of antibiotic use within ICUs. Evidence-based strategies for the prevention of VARI in resource-limited settings are lacking. Preventing the leakage of oropharyngeal secretions into the lung using continuous endotracheal cuff pressure control is a promising strategy. The aim of this study is to investigate the efficacy of automated, continuous endotracheal cuff pressure control in preventing the development of VARI and reducing antibiotic use in ICUs in Vietnam. This is an open-label randomised controlled multicentre trial. We will enrol 600 adult patients intubated for ≤ 24 h at the time of enrolment. Eligible patients will be stratified according to admission diagnosis (180 tetanus, 420 non-tetanus) and site and will be randomised in a 1:1 ratio to receive either (1) automated, continuous control of endotracheal cuff pressure or (2) intermittent measurement and control of endotracheal cuff pressure using a manual cuff pressure meter. The primary outcome is the occurrence of VARI, defined as either VAP or VAT during the ICU admission up to a maximum of 90 days after randomisation. Patients in both groups who are at risk for VARI will receive a standardised battery of investigations if their treating physician feels a new infection has occurred, the results of which will be used by an endpoint review committee, blinded to the allocated arm and independent of patient care, to determine the primary outcome. All enrolled patients will be followed for mortality and endotracheal tube cuff-related complications at 28 days and 90 days after randomisation. Other secondary outcomes include antibiotic use; days ventilated, in ICU and in hospital

Influenza vaccine efficacy in young children attending childcare: A randomised controlled trial.

PubMed

Li-Kim-Moy, Jean P; Yin, Jiehui K; Heron, Leon; Leask, Julie; Lambert, Stephen B; Nissen, Michael; Sloots, Theo; Booy, Robert

2017-01-01

Influenza causes a substantial burden in young children. Vaccine efficacy (VE) data are limited in this age group. We examined trivalent influenza vaccine (TIV) efficacy and safety in young children attending childcare. A double-blind, randomised controlled trial in children aged 6 to <48 months was conducted with recruitment from Sydney childcare centres in 2011. Children were randomised to receive two doses of TIV or control hepatitis A vaccine. Efficacy was evaluated against polymerase chain reaction-confirmed influenza using parent-collected nose/throat swabs during influenza-like-illness. Safety outcomes were assessed during 6 months of follow-up. Fifty-seven children were allocated to influenza vaccine and 67 to control; all completed the study. The influenza attack rate was 1.8 vs 13.4% in the TIV and control groups, respectively; VE 87% (95%CI: 0-98%). For children aged 24 to <48 months, 0 vs 8 (18.6%) influenza infections occurred in the TIV and control groups respectively, giving a VE of 100% (16-100%). Efficacy was not shown in children 6 to <24 months, probably due to insufficient power. Injection site and systemic adverse events were mostly mild to moderate with no significant differences, apart from more mild diarrhoea following dose 2 in TIV recipients (11.8 vs 0%). Influenza vaccine appeared efficacious in the subgroup of children aged 24 to <48 months, although caution is required due to the small number of participants. There were no serious adverse events and most parents would vaccinate again. Influenza vaccination in a childcare setting could be valuable and a larger confirmatory study would be helpful. © 2016 Paediatrics and Child Health Division (The Royal Australasian College of Physicians).

A randomised controlled trial of losartan as an anti-fibrotic agent in non-alcoholic steatohepatitis.

PubMed

McPherson, Stuart; Wilkinson, Nina; Tiniakos, Dina; Wilkinson, Jennifer; Burt, Alastair D; McColl, Elaine; Stocken, Deborah D; Steen, Nick; Barnes, Jane; Goudie, Nicola; Stewart, Stephen; Bury, Yvonne; Mann, Derek; Anstee, Quentin M; Day, Christopher P

2017-01-01

Non-alcoholic fatty liver disease (NAFLD) is a common liver disease worldwide. Experimental and small clinical trials have demonstrated that angiotensin II blockers (ARB) may be anti-fibrotic in the liver. The aim of this randomised controlled trial was to assess whether treatment with Losartan for 96 weeks slowed, halted or reversed the progression of fibrosis in patients with non-alcoholic steatohepatitis (NASH). Double-blind randomised-controlled trial of Losartan 50 mg once a day versus placebo for 96 weeks in patients with histological evidence of NASH. The primary outcome for the study was change in histological fibrosis stage from pre-treatment to end-of-treatment. The study planned to recruit 214 patients. However, recruitment was slower than expected, and after 45 patients were randomised (median age 55; 56% male; 60% diabetic; median fibrosis stage 2), enrolment was suspended. Thirty-two patients (15 losartan and 17 placebo) completed follow up period: one patient (6.7%) treated with losartan and 4 patients (23.5%) in the placebo group were "responders" (lower fibrosis stage at follow up compared with baseline). The major reason for slow recruitment was that 39% of potentially eligible patients were already taking an ARB or angiotensin converting enzyme inhibitor (ACEI), and 15% were taking other prohibited medications. Due to the widespread use of ACEI and ARB in patients with NASH this trial failed to recruit sufficient patients to determine whether losartan has anti-fibrotic effects in the liver. ISRCTN 57849521.

Robust H∞ control of active vehicle suspension under non-stationary running

NASA Astrophysics Data System (ADS)

Guo, Li-Xin; Zhang, Li-Ping

2012-12-01

Due to complexity of the controlled objects, the selection of control strategies and algorithms in vehicle control system designs is an important task. Moreover, the control problem of automobile active suspensions has been become one of the important relevant investigations due to the constrained peculiarity and parameter uncertainty of mathematical models. In this study, after establishing the non-stationary road surface excitation model, a study on the active suspension control for non-stationary running condition was conducted using robust H∞ control and linear matrix inequality optimization. The dynamic equation of a two-degree-of-freedom quarter car model with parameter uncertainty was derived. The H∞ state feedback control strategy with time-domain hard constraints was proposed, and then was used to design the active suspension control system of the quarter car model. Time-domain analysis and parameter robustness analysis were carried out to evaluate the proposed controller stability. Simulation results show that the proposed control strategy has high systemic stability on the condition of non-stationary running and parameter uncertainty (including suspension mass, suspension stiffness and tire stiffness). The proposed control strategy can achieve a promising improvement on ride comfort and satisfy the requirements of dynamic suspension deflection, dynamic tire loads and required control forces within given constraints, as well as non-stationary running condition.

Robustness of reduced-order multivariable state-space self-tuning controller

NASA Technical Reports Server (NTRS)

Yuan, Zhuzhi; Chen, Zengqiang

1994-01-01

In this paper, we present a quantitative analysis of the robustness of a reduced-order pole-assignment state-space self-tuning controller for a multivariable adaptive control system whose order of the real process is higher than that of the model used in the controller design. The result of stability analysis shows that, under a specific bounded modelling error, the adaptively controlled closed-loop real system via the reduced-order state-space self-tuner is BIBO stable in the presence of unmodelled dynamics.

LMI-Based Generation of Feedback Laws for a Robust Model Predictive Control Algorithm

NASA Technical Reports Server (NTRS)

Acikmese, Behcet; Carson, John M., III

2007-01-01

This technical note provides a mathematical proof of Corollary 1 from the paper 'A Nonlinear Model Predictive Control Algorithm with Proven Robustness and Resolvability' that appeared in the 2006 Proceedings of the American Control Conference. The proof was omitted for brevity in the publication. The paper was based on algorithms developed for the FY2005 R&TD (Research and Technology Development) project for Small-body Guidance, Navigation, and Control [2].The framework established by the Corollary is for a robustly stabilizing MPC (model predictive control) algorithm for uncertain nonlinear systems that guarantees the resolvability of the associated nite-horizon optimal control problem in a receding-horizon implementation. Additional details of the framework are available in the publication.

Management of haemothoraces in blunt thoracic trauma: study protocol for a randomised controlled trial

PubMed Central

Carver, David A; Bressan, Alexsander K; Schieman, Colin; Grondin, Sean C; Kirkpatrick, Andrew W; Lall, Rohan; McBeth, Paul B; Dunham, Michael B; Ball, Chad G

2018-01-01

Introduction Haemothorax following blunt thoracic trauma is a common source of morbidity and mortality. The optimal management of moderate to large haemothoraces has yet to be defined. Observational data have suggested that expectant management may be an appropriate strategy in stable patients. This study aims to compare the outcomes of patients with haemothoraces following blunt thoracic trauma treated with either chest drainage or expectant management. Methods and analysis This is a single-centre, dual-arm randomised controlled trial. Patients presenting with a moderate to large sized haemothorax following blunt thoracic trauma will be assessed for eligibility. Eligible patients will then undergo an informed consent process followed by randomisation to either (1) chest drainage (tube thoracostomy) or (2) expectant management. These groups will be compared for the rate of additional thoracic interventions, major thoracic complications, length of stay and mortality. Ethics and dissemination This study has been approved by the institution’s research ethics board and registered with ClinicalTrials.gov. All eligible participants will provide informed consent prior to randomisation. The results of this study may provide guidance in an area where there remains significant variation between clinicians. The results of this study will be published in peer-reviewed journals and presented at national and international conferences. Trial registration number NCT03050502. PMID:29502092

Robust control for a biaxial servo with time delay system based on adaptive tuning technique.

PubMed

Chen, Tien-Chi; Yu, Chih-Hsien

2009-07-01

A robust control method for synchronizing a biaxial servo system motion is proposed in this paper. A new network based cross-coupled control and adaptive tuning techniques are used together to cancel out the skew error. The conventional fixed gain PID cross-coupled controller (CCC) is replaced with the adaptive cross-coupled controller (ACCC) in the proposed control scheme to maintain biaxial servo system synchronization motion. Adaptive-tuning PID (APID) position and velocity controllers provide the necessary control actions to maintain synchronization while following a variable command trajectory. A delay-time compensator (DTC) with an adaptive controller was augmented to set the time delay element, effectively moving it outside the closed loop, enhancing the stability of the robust controlled system. This scheme provides strong robustness with respect to uncertain dynamics and disturbances. The simulation and experimental results reveal that the proposed control structure adapts to a wide range of operating conditions and provides promising results under parameter variations and load changes.

Robust tracking and distributed synchronization control of a multi-motor servomechanism with H-infinity performance.

PubMed

Wang, Minlin; Ren, Xuemei; Chen, Qiang

2018-01-01

The multi-motor servomechanism (MMS) is a multi-variable, high coupling and nonlinear system, which makes the controller design challenging. In this paper, an adaptive robust H-infinity control scheme is proposed to achieve both the load tracking and multi-motor synchronization of MMS. This control scheme consists of two parts: a robust tracking controller and a distributed synchronization controller. The robust tracking controller is constructed by incorporating a neural network (NN) K-filter observer into the dynamic surface control, while the distributed synchronization controller is designed by combining the mean deviation coupling control strategy with the distributed technique. The proposed control scheme has several merits: 1) by using the mean deviation coupling synchronization control strategy, the tracking controller and the synchronization controller can be designed individually without any coupling problem; 2) the immeasurable states and unknown nonlinearities are handled by a NN K-filter observer, where the number of NN weights is largely reduced by using the minimal learning parameter technique; 3) the H-infinity performances of tracking error and synchronization error are guaranteed by introducing a robust term into the tracking controller and the synchronization controller, respectively. The stabilities of the tracking and synchronization control systems are analyzed by the Lyapunov theory. Simulation and experimental results based on a four-motor servomechanism are conducted to demonstrate the effectiveness of the proposed method. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Homeopathic Arnica montana for post-tonsillectomy analgesia: a randomised placebo control trial.

PubMed

Robertson, A; Suryanarayanan, R; Banerjee, A

2007-01-01

To evaluate the efficacy of Homeopathic Arnica in reducing the morbidity following tonsillectomy. Randomised double blind, placebo controlled trial at a tertiary referral centre. 190 patients over the age of 18 undergoing tonsillectomy were randomised into intervention and control groups receiving either Arnica 30c or identical placebo, 2 tablets 6 times in the first post-operative day and then 2 tablets twice a day for the next 7 days. The primary outcome measure was the change in pain scores (visual analogue scale) recorded by the patient on a questionnaire over 14 days post-operatively; Secondary outcome measures were: analgesia consumption, visits to the GP or hospital, antibiotic usage, the day on which their swallowing returned to normal and the day on which they returned to work. 111 (58.4%) completed questionnaires were available for analysis. The Arnica group had a significantly larger drop in pain score from day 1 to day 14 (28.3) compared to the placebo group (23.8) with p < 0.05. The two groups did not differ significantly on analgesic consumption or any of the other secondary outcome measures (number of post-operative visits to GP, use of antibiotics and secondary haemorrhage readmissions). The results of this trial suggest that Arnica montana given after tonsillectomy provides a small, but statistically significant, decrease in pain scores compared to placebo.

Exercise for depression in care home residents: a randomised controlled trial with cost-effectiveness analysis (OPERA).

PubMed

Underwood, M; Lamb, S E; Eldridge, S; Sheehan, B; Slowther, A; Spencer, A; Thorogood, M; Atherton, N; Bremner, S A; Devine, A; Diaz-Ordaz, K; Ellard, D R; Potter, R; Spanjers, K; Taylor, S J C

2013-05-01

Many older people living in care homes (long term residential care or nursing homes) are depressed. Exercise is a promising non-drug intervention for preventing and treating depression in this population. To evaluate the impact of a 'whole-home' intervention, consisting of training for residential and nursing home staff backed up with a twice-weekly, physiotherapist-led exercise class on depressive symptoms in care home residents. A cluster randomised controlled trial with a cost-effectiveness analysis to compare (1) the prevalence of depression in intervention homes with that in control homes in all residents contributing data 12 months after homes were randomised (cross-sectional analysis); (2) the number of depressive symptoms at 6 months between intervention and control homes in residents who were depressed at pre-randomisation baseline assessment (depressed cohort comparison); and (3) the number of depressive symptoms at 12 months between intervention and control homes in all residents who were present at pre-randomisation baseline assessment (cohort comparison). Seventy-eight care homes in Coventry and Warwickshire and north-east London. Care home residents aged ≥ 65 years. Control intervention: Depression awareness training programme for care home staff. Active intervention: A 'whole-home' exercise intervention, consisting of training for care home staff backed up with a twice-weekly, physiotherapist-led exercise group. Geriatric Depression Scale-15, proxy European Quality of Life-5 Dimensions (EQ-5D), cost-effectiveness from an National Health Service perspective, peripheral fractures and death. We recruited a total of 1054 participants. Cross-sectional analysis: We obtained 595 Geriatric Depression Scale-15 scores and 724 proxy EQ-5D scores. For the cohort analyses we obtained 765 baseline Geriatric Depression Scale-15 scores and 776 proxy EQ-5D scores. Of the 781 who we assessed prior to randomisation, 765 provided a Geriatric Depression Scale-15 score

Robust controller design for flexible structures using normalized coprime factor plant descriptions

NASA Technical Reports Server (NTRS)

Armstrong, Ernest S.

1993-01-01

Stabilization is a fundamental requirement in the design of feedback compensators for flexible structures. The search for the largest neighborhood around a given design plant for which a single controller produces closed-loop stability can be formulated as an H(sub infinity) control problem. The use of normalized coprime factor plant descriptions, in which the plant perturbations are defined as additive modifications to the coprime factors, leads to a closed-form expression for the maximum neighborhood boundary allowing optimal and suboptimal H(sub infinity) compensators to be computed directly without the usual gamma iteration. A summary of the theory on robust stabilization using normalized coprime factor plant descriptions is presented, and the application of the theory to the computation of robustly stable compensators for the phase version of the Control-Structures Interaction (CSI) Evolutionary Model is described. Results from the application indicate that the suboptimal version of the theory has the potential of providing the bases for the computation of low-authority compensators that are robustly stable to expected variations in design model parameters and additive unmodeled dynamics.

Robust control of integrated motor-transmission powertrain system over controller area network for automotive applications

NASA Astrophysics Data System (ADS)

Zhu, Xiaoyuan; Zhang, Hui; Cao, Dongpu; Fang, Zongde

2015-06-01

Integrated motor-transmission (IMT) powertrain system with directly coupled motor and gearbox is a good choice for electric commercial vehicles (e.g., pure electric buses) due to its potential in motor size reduction and energy efficiency improvement. However, the controller design for powertrain oscillation damping becomes challenging due to the elimination of damping components. On the other hand, as controller area network (CAN) is commonly adopted in modern vehicle system, the network-induced time-varying delays that caused by bandwidth limitation will further lead to powertrain vibration or even destabilize the powertrain control system. Therefore, in this paper, a robust energy-to-peak controller is proposed for the IMT powertrain system to address the oscillation damping problem and also attenuate the external disturbance. The control law adopted here is based on a multivariable PI control, which ensures the applicability and performance of the proposed controller in engineering practice. With the linearized delay uncertainties characterized by polytopic inclusions, a delay-free closed-loop augmented system is established for the IMT powertrain system under discrete-time framework. The proposed controller design problem is then converted to a static output feedback (SOF) controller design problem where the feedback control gains are obtained by solving a set of linear matrix inequalities (LMIs). The effectiveness as well as robustness of the proposed controller is demonstrated by comparing its performance against that of a conventional PI controller.

Frontal lesions predict response to prism adaptation treatment in spatial neglect: A randomised controlled study.

PubMed

Goedert, Kelly M; Chen, Peii; Foundas, Anne L; Barrett, A M

2018-03-20

Spatial neglect commonly follows right hemisphere stroke. It is defined as impaired contralesional stimulus detection, response, or action, causing functional disability. While prism adaptation treatment is highly promising to promote functional recovery of spatial neglect, not all individuals respond. Consistent with a primary effect of prism adaptation on spatial movements, we previously demonstrated that functional improvement after prism adaptation treatment is linked to frontal lobe lesions. However, that study was a treatment-only study with no randomised control group. The current study randomised individuals with spatial neglect to receive 10 days of prism adaptation treatment or to receive only standard care (control group). Replicating our earlier results, we found that the presence of frontal lesions moderated response to prism adaptation treatment: among prism-treated patients, only those with frontal lesions demonstrated functional improvements in their neglect symptoms. Conversely, among individuals in the standard care control group, the presence of frontal lesions did not modify recovery. These results suggest that further research is needed on how frontal lesions may predict response to prism adaptation treatment. Additionally, the results help elucidate the neural network involved in spatial movement and could be used to aid decisions about treatment.

A randomised controlled trial of empowerment training for Chinese abused pregnant women in Hong Kong.

PubMed

Tiwari, A; Leung, W C; Leung, T W; Humphreys, J; Parker, B; Ho, P C

2005-09-01

To evaluate the effectiveness of an empowerment intervention in reducing intimate partner violence (IPV) and improving health status. Randomised controlled trial. Antenatal clinic in a public hospital in Hong Kong. One hundred and ten Chinese pregnant women with a history of abuse by their intimate partners. Women were randomised to the experimental or control group. Experimental group women received empowerment training specially designed for Chinese abused pregnant women while the control group women received standard care for abused women. Data were collected at study entry and six weeks postnatal. IPV [on the Conflict Tactics Scale (CTS)], health-related quality of life (SF-36) and postnatal depression [Edinburgh Postnatal Depression Scale (EPDS)]. Following the training, the experimental group had significantly higher physical functioning and had significantly improved role limitation due to physical problems and emotional problems. They also reported less psychological (but not sexual) abuse, minor (but not severe) physical violence and had significantly lower postnatal depression scores. However, they reported more bodily pain. An empowerment intervention specially designed for Chinese abused pregnant women was effective in reducing IPV and improving the health status of the women.

Persistent occiput posterior: OUTcomes following digital rotation: a pilot randomised controlled trial.

PubMed

Graham, Kathryn; Phipps, Hala; Hyett, Jon A; Ludlow, Joanne P; Mackie, Adam; Marren, Anthony; De Vries, Bradley

2014-06-01

To determine the feasibility of a multicentre randomised controlled trial (RCT) to investigate whether digital rotation of the fetal head from occiput posterior (OP) position in the second stage of labour reduces the risk of operative delivery (defined as caesarean section (CS) or instrumental delivery). We conducted the study between December 2010 and December 2011 in a tertiary referral hospital in Australia. A transabdominal ultrasound was performed early in the second stage of labour on women with cephalic, singleton pregnancies to determine the fetal position. Those women with a fetus in the OP position were randomised to either a digital rotation or a sham procedure. In all other ways, participants received their usual intrapartum care. Data regarding demographics, mode of delivery, labour, post natal period and neonatal outcomes were collected. One thousand and four women were consented, 834 achieved full dilatation, and 30 were randomised. An additional portable ultrasound scan and a blinded 'sham' digital rotation were acceptable to women and staff. Operative delivery rates were 13/15 in the digital rotation (four CS and nine instrumental) and 12/15 in the sham (three CS and nine instrumental) groups, respectively. A large double-blinded multicentre RCT would be feasible and acceptable to women and staff. Strategies to improve recruitment such as consenting women with an effective epidural in active labour should be considered. This would be the first RCT to answer a clinically important question which could significantly affect the operative delivery rate in Australia and internationally. © 2014 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.

Robust fuel- and time-optimal control of uncertain flexible space structures

NASA Technical Reports Server (NTRS)

Wie, Bong; Sinha, Ravi; Sunkel, John; Cox, Ken

1993-01-01

The problem of computing open-loop, fuel- and time-optimal control inputs for flexible space structures in the face of modeling uncertainty is investigated. Robustified, fuel- and time-optimal pulse sequences are obtained by solving a constrained optimization problem subject to robustness constraints. It is shown that 'bang-off-bang' pulse sequences with a finite number of switchings provide a practical tradeoff among the maneuvering time, fuel consumption, and performance robustness of uncertain flexible space structures.

Robust dynamic inversion controller design and analysis (using the X-38 vehicle as a case study)

NASA Astrophysics Data System (ADS)

Ito, Daigoro

A new way to approach robust Dynamic Inversion controller synthesis is addressed in this paper. A Linear Quadratic Gaussian outer-loop controller improves the robustness of a Dynamic Inversion inner-loop controller in the presence of uncertainties. Desired dynamics are given by the dynamic compensator, which shapes the loop. The selected dynamics are based on both performance and stability robustness requirements. These requirements are straightforwardly formulated as frequency-dependent singular value bounds during synthesis of the controller. Performance and robustness of the designed controller is tested using a worst case time domain quadratic index, which is a simple but effective way to measure robustness due to parameter variation. Using this approach, a lateral-directional controller for the X-38 vehicle is designed and its robustness to parameter variations and disturbances is analyzed. It is found that if full state measurements are available, the performance of the designed lateral-directional control system, measured by the chosen cost function, improves by approximately a factor of four. Also, it is found that the designed system is stable up to a parametric variation of 1.65 standard deviation with the set of uncertainty considered. The system robustness is determined to be highly sensitive to the dihedral derivative and the roll damping coefficients. The controller analysis is extended to the nonlinear system where both control input displacements and rates are bounded. In this case, the considered nonlinear system is stable up to 48.1° in bank angle and 1.59° in sideslip angle variations, indicating it is more sensitive to variations in sideslip angle than in bank angle. This nonlinear approach is further extended for the actuator failure mode analysis. The results suggest that the designed system maintains a high level of stability in the event of aileron failure. However, only 35% or less of the original stability range is maintained for the

Educational Benefits of Using Game Consoles in a Primary Classroom: A Randomised Controlled Trial

ERIC Educational Resources Information Center

Miller, David J.; Robertson, Derek P.

2011-01-01

It is known that computer games are motivating for children, but there is limited direct evidence of their effects on classroom learning. The studies that are available tend to be limited in terms of output data reported, or small in scale, or both. The aim of this randomised controlled trial was to upscale a recent study by Miller and Robertson…

Robust stabilization control based on guardian maps theory for a longitudinal model of hypersonic vehicle.

PubMed

Liu, Yanbin; Liu, Mengying; Sun, Peihua

2014-01-01

A typical model of hypersonic vehicle has the complicated dynamics such as the unstable states, the nonminimum phases, and the strong coupling input-output relations. As a result, designing a robust stabilization controller is essential to implement the anticipated tasks. This paper presents a robust stabilization controller based on the guardian maps theory for hypersonic vehicle. First, the guardian maps theories are provided to explain the constraint relations between the open subsets of complex plane and the eigenvalues of the state matrix of closed-loop control system. Then, a general control structure in relation to the guardian maps theories is proposed to achieve the respected design demands. Furthermore, the robust stabilization control law depending on the given general control structure is designed for the longitudinal model of hypersonic vehicle. Finally, a simulation example is provided to verify the effectiveness of the proposed methods.

Randomised controlled trial of a mobile phone infant resuscitation guide.

PubMed

Hawkes, Gavin A; Murphy, Geraldine; Dempsey, Eugene M; Ryan, Anthony C

2015-11-01

The aim of this study was to develop a mobile phone resuscitation guide (MPRG) and to evaluate its use during simulated resuscitation of a mannequin. An MPRG was developed using EpiSurveyor. A randomised controlled trial was performed in school-going children aged 15-16 years. All subjects were taught infant CPR skills using the American Heart Association Infant CPR Anytime. Two weeks later, the students were randomised to use of MPRG or not, and their CPR skills were re-assessed. The assessment was conducted using previously validated checklists. Twenty-one students participated in this trial. The MPRG group performed notably better in the areas of calling emergency services (80% vs. 36.4%, P = 0.044), completing sufficient CPR cycles (90% vs. 45.5%, P = 0.047) and following the correct CPR sequence (60% vs. 9.1%, P = 0.013). No difference in resuscitation skills of participants was observed. We have shown that participants were more likely to call emergency services if they were using the MPRG. Further trials are needed to investigate the utility of mobile phone guides and whether or not they can reduce the time taken to contact emergency services as well as if they can sustain correct CPR sequence in an in-vivo setting. © 2015 The Authors. Journal of Paediatrics and Child Health © 2015 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

Effectiveness and cost-effectiveness of humanistic counselling in schools for young people with emotional distress (ETHOS): study protocol for a randomised controlled trial.

PubMed

Stafford, Megan Rose; Cooper, Mick; Barkham, Michael; Beecham, Jeni; Bower, Peter; Cromarty, Karen; Fugard, Andrew J B; Jackson, Charlie; Pearce, Peter; Ryder, Rebekah; Street, Cathy

2018-03-09

One in ten children in Britain have been identified as experiencing a diagnosable mental health disorder. School-based humanistic counselling (SBHC) may help young people identify, address, and overcome psychological distress. Data from four pilot trials suggest that SBHC may be clinically effective. However, a fully powered randomised controlled trial (RCT) is needed to provide a robust test of its effectiveness, to assess its cost-effectiveness, and to determine the process of change. The Effectiveness and Cost-effectiveness Trial of Humanistic Counselling in Schools (ETHOS) is a two-arm, parallel-group RCT comparing the clinical and cost-effectiveness of SBHC with Pastoral Care as Usual (PCAU) in school settings. Eligibility criteria for young people include being between 13 and 16 years of age and experiencing moderate to severe levels of emotional distress. Participants are randomised to receive either SBHC or PCAU. SBHC is delivered in up to 10 weekly, individual sessions in their school with a qualified, experienced counsellor who has also received training using a clinical practice manual. Adherence to the SBHC model is assessed by a sub-team of auditors and in clinical supervision. PCAU consists of the schools' pre-existing systems for supporting the emotional health and well-being of students. The primary outcomes are psychological distress measured using the Young Person's Clinical Outcomes in Routine Evaluation (YP-CORE) and costs evaluated using the Client Service Receipt Inventory (CSRI). Secondary outcomes include psychological difficulties, levels of depression, anxiety and self-esteem, well-being, school engagement, educational outcomes and achievement of personal goals. Qualitative interviews with participants, parents and school staff will look to identify the mechanisms of change in SBHC. Researchers administering the measures are blind to allocation. The trial requires n = 306 participants (n = 153 in each group), with 90% power to detect a

Adolescents’ use of purpose built shade in secondary schools: cluster randomised controlled trial

PubMed Central

White, Vanessa; Wakefield, Melanie A; Jamsen, Kris M; White, Victoria; Livingston, Patricia M; English, Dallas R; Simpson, Julie A

2009-01-01

Objective To examine whether students use or avoid newly shaded areas created by shade sails installed at schools. Design Cluster randomised controlled trial with secondary schools as the unit of randomisation. Setting 51 secondary schools with limited available shade, in Australia, assessed over two spring and summer terms. Participants Students outside at lunch times. Intervention Purpose built shade sails were installed in winter 2005 at full sun study sites to increase available shade for students in the school grounds. Main outcome measure Mean number of students using the primary study sites during weekly observations at lunch time. Results Over the study period the mean change in students using the primary study site from pre-test to post-test was 2.63 (95% confidence interval 0.87 to 4.39) students in intervention schools and −0.03 (−1.16 to 1.09) students in control schools. The difference in mean change between groups was 2.67 (0.65 to 4.68) students (P=0.011). Conclusions Students used rather than avoided newly shaded areas provided by purpose built shade sails at secondary schools in this trial, suggesting a practical means of reducing adolescents’ exposure to ultraviolet radiation. Trial registration Exempt. PMID:19223344

Interventions for preventing or treating alcohol hangover: systematic review of randomised controlled trials

PubMed Central

Pittler, Max H; Verster, Joris C; Ernst, Edzard

2005-01-01

Objective To assess the clinical evidence on the effectiveness of any medical intervention for preventing or treating alcohol hangover. Data sources Systematic searches on Medline, Embase, Amed, Cochrane Central, the National Research Register (UK), and ClincalTrials.gov (USA); hand searches of conference proceedings and bibliographies; contact with experts and manufacturers of commercial preparations. Language of publication was not restricted. Study selection and data extraction All randomised controlled trials of any medical intervention for preventing or treating alcohol hangover were included. Trials were considered if they were placebo controlled or controlled against a comparator intervention. Titles and abstracts of identified articles were read and hard copies were obtained. The selection of studies, data extraction, and validation were done independently by two reviewers. The Jadad score was used to evaluate methodological quality. Results Fifteen potentially relevant trials were identified. Seven publications failed to meet all inclusion criteria. Eight randomised controlled trials assessing eight different interventions were reviewed. The agents tested were propranolol, tropisetron, tolfenamic acid, fructose or glucose, and the dietary supplements Borago officinalis (borage), Cynara scolymus (artichoke), Opuntia ficus-indica (prickly pear), and a yeast based preparation. All studies were double blind. Significant intergroup differences for overall symptom scores and individual symptoms were reported only for tolfenamic acid, γ linolenic acid from B officinalis, and a yeast based preparation. Conclusion No compelling evidence exists to suggest that any conventional or complementary intervention is effective for preventing or treating alcohol hangover. The most effective way to avoid the symptoms of alcohol induced hangover is to practise abstinence or moderation. PMID:16373736

All-Wales licensed premises intervention (AWLPI): a randomised controlled trial to reduce alcohol-related violence

PubMed Central

2014-01-01

Background Alcohol-related violence in and in the vicinity of licensed premises continues to place a considerable burden on the United Kingdom’s (UK) health services. Robust interventions targeted at licensed premises are therefore required to reduce the costs of alcohol-related harm. Previous evaluations of interventions in licensed premises have a number of methodological limitations and none have been conducted in the UK. The aim of the trial was to determine the effectiveness of the Safety Management in Licensed Environments intervention designed to reduce alcohol-related violence in licensed premises, delivered by Environmental Health Officers, under their statutory authority to intervene in cases of violence in the workplace. Methods/Design A national randomised controlled trial, with licensed premises as the unit of allocation. Premises were identified from all 22 Local Authorities in Wales. Eligible premises were those with identifiable violent incidents on premises, using police recorded violence data. Premises were allocated to intervention or control by optimally balancing by Environmental Health Officer capacity in each Local Authority, number of violent incidents in the 12 months leading up to the start of the project and opening hours. The primary outcome measure is the difference in frequency of violence between intervention and control premises over a 12 month follow-up period, based on a recurrent event model. The trial incorporates an embedded process evaluation to assess intervention implementation, fidelity, reach and reception, and to interpret outcome effects, as well as investigate its economic impact. Discussion The results of the trial will be applicable to all statutory authorities directly involved with managing violence in the night time economy and will provide the first formal test of Health and Safety policy in this environment. If successful, opportunities for replication and generalisation will be considered. Trial registration

A systematic review of randomised controlled trials on the effectiveness of exercise programs on Lumbo Pelvic Pain among postnatal women.

PubMed

Tseng, Pei-Ching; Puthussery, Shuby; Pappas, Yannis; Gau, Meei-Ling

2015-11-26

A substantial number of women tend to be affected by Lumbo Pelvic Pain (LPP) following child birth. Physical exercise is indicated as a beneficial method to relieve LPP, but individual studies appear to suggest mixed findings about its effectiveness. This systematic review aimed to synthesise evidence from randomised controlled trials on the effectiveness of exercise on LPP among postnatal women to inform policy, practice and future research. A systematic review was conducted of all randomised controlled trials published between January 1990 and July 2014, identified through a comprehensive search of following databases: PubMed, PEDro, Embase, Cinahl, Medline, SPORTDiscus, Cochrane Pregnancy and Childbirth Group's Trials Register, and electronic libraries of authors'institutions. Randomised controlled trials were eligible for inclusion if the intervention comprised of postnatal exercise for women with LPP onset during pregnancy or within 3 months after delivery and the outcome measures included changes in LPP. Selected articles were assessed using the PEDro Scale for methodological quality and findings were synthesised narratively as meta-analysis was found to be inappropriate due to heterogeneity among included studies. Four randomised controlled trials were included, involving 251 postnatal women. Three trials were rated as of 'good' methodological quality. All trials, except one, were at low risk of bias. The trials included physical exercise programs with varying components, differing modes of delivery, follow up times and outcome measures. Intervention in one trial, involving physical therapy with specific stabilising exercises, proved to be effective in reducing LPP intensity. An improvement in gluteal pain on the right side was reported in another trial and a significant difference in pain frequency in another. Our review indicates that only few randomised controlled trials have evaluated the effectiveness of exercise on LPP among postnatal women. There is

Pharmacist-led management of chronic pain in primary care: results from a randomised controlled exploratory trial

PubMed Central

Bruhn, Hanne; Bond, Christine M; Elliott, Alison M; Hannaford, Philip C; Lee, Amanda J; McNamee, Paul; Smith, Blair H; Watson, Margaret C; Holland, Richard; Wright, David

2013-01-01

Objectives To compare the effectiveness of pharmacist medication review, with or without pharmacist prescribing, with standard care, for patients with chronic pain. Design An exploratory randomised controlled trial. Setting Six general practices with prescribing pharmacists in Grampian (3) and East Anglia (3). Participants Patients on repeat prescribed pain medication (4815) were screened by general practitioners (GPs), and mailed invitations (1397). 196 were randomised and 180 (92%) completed. Exclusion criteria included: severe mental illness, terminally ill, cancer related pain, history of addiction. Randomisation and intervention Patients were randomised using a remote telephone service to: (1) pharmacist medication review with face-to-face pharmacist prescribing; (2) pharmacist medication review with feedback to GP and no planned patient contact or (3) treatment as usual (TAU). Blinding was not possible. Outcome measures Outcomes were the SF-12v2, the Chronic Pain Grade (CPG), the Health Utilities Index 3 and the Hospital Anxiety and Depression Scale (HADS). Outcomes were collected at 0, 3 and 6 months. Results In the prescribing arm (n=70) two patients were excluded/nine withdrew. In the review arm (n=63) one was excluded/three withdrew. In the TAU arm (n=63) four withdrew. Compared with baseline, patients had an improved CPG in the prescribing arm, 47.7% (21/44; p=0.003) and in the review arm, 38.6% (17/44; p=0.001), but not the TAU group, 31.3% (15/48; ns). The SF-12 Physical Component Score showed no effect in the prescribing or review arms but improvement in TAU (p=0.02). The SF-12 Mental Component Score showed no effect for the prescribing or review arms and deterioration in the TAU arm (p=0.002). HADS scores improved within the prescribing arm for depression (p=0.022) and anxiety (p=0.007), between groups (p=0.022 and p=0.045, respectively). Conclusions This is the first randomised controlled trial of pharmacist prescribing in the UK, and suggests

Robust Takagi-Sugeno fuzzy control for fractional order hydro-turbine governing system.

PubMed

Wang, Bin; Xue, Jianyi; Wu, Fengjiao; Zhu, Delan

2016-11-01

A robust fuzzy control method for fractional order hydro-turbine governing system (FOHGS) in the presence of random disturbances is investigated in this paper. Firstly, the mathematical model of FOHGS is introduced, and based on Takagi-Sugeno (T-S) fuzzy rules, the generalized T-S fuzzy model of FOHGS is presented. Secondly, based on fractional order Lyapunov stability theory, a novel T-S fuzzy control method is designed for the stability control of FOHGS. Thirdly, the relatively loose sufficient stability condition is acquired, which could be transformed into a group of linear matrix inequalities (LMIs) via Schur complement as well as the strict mathematical derivation is given. Furthermore, the control method could resist random disturbances, which shows the good robustness. Simulation results indicate the designed fractional order T-S fuzzy control scheme works well compared with the existing method. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

The effectiveness and cost-effectiveness of a mindfulness training programme in schools compared with normal school provision (MYRIAD): study protocol for a randomised controlled trial.

PubMed

Kuyken, Willem; Nuthall, Elizabeth; Byford, Sarah; Crane, Catherine; Dalgleish, Tim; Ford, Tamsin; Greenberg, Mark T; Ukoumunne, Obioha C; Viner, Russell M; Williams, J Mark G

2017-04-26

Mindfulness-based approaches for adults are effective at enhancing mental health, but few controlled trials have evaluated their effectiveness or cost-effectiveness for young people. The primary aim of this trial is to evaluate the effectiveness and cost-effectiveness of a mindfulness training (MT) programme to enhance mental health, wellbeing and social-emotional behavioural functioning in adolescence. To address this aim, the design will be a superiority, cluster randomised controlled, parallel-group trial in which schools offering social and emotional provision in line with good practice (Formby et al., Personal, Social, Health and Economic (PSHE) Education: A mapping study of the prevalent models of delivery and their effectiveness, 2010; OFSTED, Not Yet Good Enough: Personal, Social, Health and Economic Education in schools, 2013) will be randomised to either continue this provision (control) or include MT in this provision (intervention). The study will recruit and randomise 76 schools (clusters) and 5700 school students aged 12 to 14 years, followed up for 2 years. The study will contribute to establishing if MT is an effective and cost-effective approach to promoting mental health in adolescence. International Standard Randomised Controlled Trials, identifier: ISRCTN86619085 . Registered on 3 June 2016.

A Robust Inner and Outer Loop Control Method for Trajectory Tracking of a Quadrotor

PubMed Central

Xia, Dunzhu; Cheng, Limei; Yao, Yanhong

2017-01-01

In order to achieve the complicated trajectory tracking of quadrotor, a geometric inner and outer loop control scheme is presented. The outer loop generates the desired rotation matrix for the inner loop. To improve the response speed and robustness, a geometric SMC controller is designed for the inner loop. The outer loop is also designed via sliding mode control (SMC). By Lyapunov theory and cascade theory, the closed-loop system stability is guaranteed. Next, the tracking performance is validated by tracking three representative trajectories. Then, the robustness of the proposed control method is illustrated by trajectory tracking in presence of model uncertainty and disturbances. Subsequently, experiments are carried out to verify the method. In the experiment, ultra wideband (UWB) is used for indoor positioning. Extended Kalman Filter (EKF) is used for fusing inertial measurement unit (IMU) and UWB measurements. The experimental results show the feasibility of the designed controller in practice. The comparative experiments with PD and PD loop demonstrate the robustness of the proposed control method. PMID:28925984

Wordless intervention for people with epilepsy and learning disabilities (WIELD): a randomised controlled feasibility trial

PubMed Central

Mengoni, Silvana E; Gates, Bob; Parkes, Georgina; Wellsted, David; Barton, Garry; Ring, Howard; Khoo, Mary Ellen; Monji-Patel, Deela; Friedli, Karin; Zia, Asif; Irvine, Lisa; Durand, Marie-Anne

2016-01-01

Objective To investigate the feasibility of a full-scale randomised controlled trial of a picture booklet to improve quality of life for people with epilepsy and learning disabilities. Trial design A randomised controlled feasibility trial. Randomisation was not blinded and was conducted using a centralised secure database and a blocked 1:1 allocation ratio. Setting Epilepsy clinics in 1 English National Health Service (NHS) Trust. Participants Patients with learning disabilities and epilepsy who had: a seizure within the past 12 months, meaningful communication and a carer with sufficient proficiency in English. Intervention Participants in the intervention group used a picture booklet with a trained researcher, and a carer present. These participants kept the booklet, and were asked to use it at least twice more over 20 weeks. The control group received treatment as usual, and were provided with a booklet at the end of the study. Outcome measures 7 feasibility criteria were used relating to recruitment, data collection, attrition, potential effect on epilepsy-related quality of life (Epilepsy and Learning Disabilities Quality of Life Scale, ELDQOL) at 4-week, 12-week and 20-week follow-ups, feasibility of methodology, acceptability of the intervention and potential to calculate cost-effectiveness. Outcome The recruitment rate of eligible patients was 34% and the target of 40 participants was reached. There was minimal missing data and attrition. An intention-to-treat analysis was performed; data from the outcome measures suggest a benefit from the intervention on the ELDQOL behaviour and mood subscales at 4 and 20 weeks follow-up. The booklet and study methods were positively received, and no adverse events were reported. There was a positive indication of the potential for a cost-effectiveness analysis. Conclusions All feasibility criteria were fully or partially met, therefore confirming feasibility of a definitive trial. Trial registration number ISRCTN

A randomised placebo-controlled trial of early treatment of the patent ductus arteriosus.

PubMed

Kluckow, Martin; Jeffery, Michele; Gill, Andy; Evans, Nick

2014-03-01

Failure of closure of the patent ductus arteriosus (PDA) may be associated with harm. Early cardiac ultrasound-targeted treatment of a large PDA may result in a reduction in adverse outcomes and need for later PDA closure with no increase in adverse effects. Multicentre, double-blind, placebo-controlled randomised trial. Three neonatal intensive care units in Australia. Eligible infants born <29 weeks were screened for a large PDA and received indomethacin or placebo before age 12 h. Death or abnormal cranial ultrasound. The trial ceased enrolment early due to lack of availability of indomethacin. 164 eligible infants were screened before 12 h; of the 92 infants with a large PDA, 44 were randomised to indomethacin and 48 to placebo. There was no difference in the main outcome between groups. Infants receiving early indomethacin had significantly less early pulmonary haemorrhage (PH) (2% vs 21%), a trend towards less periventricular/intraventricular haemorrhage (PIVH) (4.5% vs 12.5%) and were less likely to receive later open-label treatment for a PDA (20% vs 40%). The 72 non-randomised infants with a small PDA were at low risk of pulmonary haemorrhage and had an 80% spontaneous PDA closure rate. Early cardiac ultrasound-targeted treatment of a large PDA is feasible and safe, resulted in a reduction in early pulmonary haemorrhage and later medical treatment but had no effect on the primary outcome of death or abnormal cranial ultrasound. Australian New Zealand Clinical Trials Registry (ACTRN12608000295347).

A robust model predictive control algorithm for uncertain nonlinear systems that guarantees resolvability

NASA Technical Reports Server (NTRS)

Acikmese, Ahmet Behcet; Carson, John M., III

2006-01-01

A robustly stabilizing MPC (model predictive control) algorithm for uncertain nonlinear systems is developed that guarantees resolvability. With resolvability, initial feasibility of the finite-horizon optimal control problem implies future feasibility in a receding-horizon framework. The control consists of two components; (i) feed-forward, and (ii) feedback part. Feed-forward control is obtained by online solution of a finite-horizon optimal control problem for the nominal system dynamics. The feedback control policy is designed off-line based on a bound on the uncertainty in the system model. The entire controller is shown to be robustly stabilizing with a region of attraction composed of initial states for which the finite-horizon optimal control problem is feasible. The controller design for this algorithm is demonstrated on a class of systems with uncertain nonlinear terms that have norm-bounded derivatives and derivatives in polytopes. An illustrative numerical example is also provided.

Venous leg ulcer healing with electric stimulation therapy: a pilot randomised controlled trial.

PubMed

Miller, C; McGuiness, W; Wilson, S; Cooper, K; Swanson, T; Rooney, D; Piller, N; Woodward, M

2017-03-02

Compression therapy is a gold standard treatment to promote venous leg ulcer (VLU) healing. Concordance with compression therapy is, however, often sub-optimal. The aim of this study was to evaluate the effectiveness of electric stimulation therapy (EST) to facilitate healing of VLUs among people who do not use moderate-to-high levels of compression (>25 mmHg). A pilot multicentre, single-blinded randomised controlled trial was conducted. Participants were randomised (2:1) to the intervention group or a control group where EST or a sham device was used 4 times daily for 20 minutes per session. Participants were monitored fortnightly for eight weeks. The primary outcome measure was percentage of area (wound size) change. In the 23 patients recruited, an average redution in wound size of 23.15% (standard deviation [SD]: 61.23) was observed for the control group compared with 32.67 % (SD: 42.54) for the intervention. A moderate effect size favouring the intervention group was detected from univariate [F(1,18)=1.588, p=0.224, partial eta squared=0.081] and multivariate repeated measures [F(1,18)=2.053, p=0.169, partial eta squared=0.102] analyses. The pilot study was not powered to detect statistical significance, however, the difference in healing outcomes are encouraging. EST may be an effective adjunct treatment among patients who have experienced difficulty adhering to moderate-to-high levels of compression therapy.

Emulating DC constant power load: a robust sliding mode control approach

NASA Astrophysics Data System (ADS)

Singh, Suresh; Fulwani, Deepak; Kumar, Vinod

2017-09-01

This article presents emulation of a programmable power electronic, constant power load (CPL) using a dc/dc step-up (boost) converter. The converter is controlled by a robust sliding mode controller (SMC). A novel switching surface is proposed to ensure a required power sunk by the converter. The proposed dc CPL is simple in design, has fast dynamic response and high accuracy, and offers an inexpensive alternative to study converters for cascaded dc distribution power system applications. Furthermore, the proposed CPL is sufficiently robust against the input voltage variations. A laboratory prototype of the proposed dc CPL has been developed and validated with SMC realised through OPAL-RT platform. The capability of the proposed dc CPL is confirmed via experimentations in varied scenarios.

Adjunctive rifampicin to reduce early mortality from Staphylococcus aureus bacteraemia (ARREST): study protocol for a randomised controlled trial.

PubMed

Thwaites, Guy; Auckland, Cressida; Barlow, Gavin; Cunningham, Richard; Davies, Gerry; Edgeworth, Jonathan; Greig, Julia; Hopkins, Susan; Jeyaratnam, Dakshika; Jenkins, Neil; Llewelyn, Martin; Meisner, Sarah; Nsutebu, Emmanuel; Planche, Tim; Read, Robert C; Scarborough, Matthew; Soares, Marta; Tilley, Robert; Török, M Estée; Williams, John; Wilson, Peter; Wyllie, Sarah; Walker, A Sarah

2012-12-18

Staphylococcus aureus bacteraemia is a common and serious infection, with an associated mortality of ~25%. Once in the blood, S. aureus can disseminate to infect almost any organ, but bones, joints and heart valves are most frequently affected. Despite the infection's severity, the evidence guiding optimal antibiotic therapy is weak: fewer than 1,500 patients have been included in 16 randomised controlled trials investigating S. aureus bacteraemia treatment. It is uncertain which antibiotics are most effective, their route of administration and duration, and whether antibiotic combinations are better than single agents. We hypothesise that adjunctive rifampicin, given in combination with a standard first-line antibiotic, will enhance killing of S. aureus early in the treatment course, sterilise infected foci and blood faster, and thereby reduce the risk of dissemination, metastatic infection and death. Our aim is to determine whether adjunctive rifampicin reduces all-cause mortality within 14 days and bacteriological failure or death within 12 weeks from randomisation. We will perform a parallel group, randomised (1:1), blinded, placebo-controlled trial in NHS hospitals across the UK. Adults (≥ 18 years) with S. aureus (meticillin-susceptible or resistant) grown from at least one blood culture who have received ≤ 96 h of active antibiotic therapy for the current infection and do not have contraindications to the use of rifampicin will be eligible for inclusion. Participants will be randomised to adjunctive rifampicin (600-900 mg/day; orally or intravenously) or placebo for the first 14 days of therapy in combination with standard single-agent antibiotic therapy. The co-primary outcome measures will be all-cause mortality up to 14 days from randomisation and bacteriological failure/death (all-cause) up to 12 weeks from randomisation. 940 patients will be recruited, providing >80% power to detect 45% and 30% reductions in the two co-primary endpoints of death by

Robust Controller for Turbulent and Convective Boundary Layers

DTIC Science & Technology

2006-08-01

filter and an optimal regulator. The Kalman filter equation and the optimal regulator equation corresponding to the state-space equations, (2.20), are...separate steady-state algebraic Riccati equations. The Kalman filter is used here as a state observer rather than as an estimator since no noises are...2001) which will not be repeated here. For robustness, in the design, the Kalman filter input matrix G has been set equal to the control input

Robust Stabilization Control Based on Guardian Maps Theory for a Longitudinal Model of Hypersonic Vehicle

PubMed Central

Liu, Mengying; Sun, Peihua

2014-01-01

A typical model of hypersonic vehicle has the complicated dynamics such as the unstable states, the nonminimum phases, and the strong coupling input-output relations. As a result, designing a robust stabilization controller is essential to implement the anticipated tasks. This paper presents a robust stabilization controller based on the guardian maps theory for hypersonic vehicle. First, the guardian maps theories are provided to explain the constraint relations between the open subsets of complex plane and the eigenvalues of the state matrix of closed-loop control system. Then, a general control structure in relation to the guardian maps theories is proposed to achieve the respected design demands. Furthermore, the robust stabilization control law depending on the given general control structure is designed for the longitudinal model of hypersonic vehicle. Finally, a simulation example is provided to verify the effectiveness of the proposed methods. PMID:24795535

Relevance of randomised controlled trials in oncology.

PubMed

Tannock, Ian F; Amir, Eitan; Booth, Christopher M; Niraula, Saroj; Ocana, Alberto; Seruga, Bostjan; Templeton, Arnoud J; Vera-Badillo, Francisco

2016-12-01

Well-designed randomised controlled trials (RCTs) can prevent bias in the comparison of treatments and provide a sound basis for changes in clinical practice. However, the design and reporting of many RCTs can render their results of little relevance to clinical practice. In this Personal View, we discuss the limitations of RCT data and suggest some ways to improve the clinical relevance of RCTs in the everyday management of patients with cancer. RCTs should ask questions of clinical rather than commercial interest, avoid non-validated surrogate endpoints in registration trials, and have entry criteria that allow inclusion of all patients who are fit to receive treatment. Furthermore, RCTs should be reported with complete accounting of frequency and management of toxicities, and with strict guidelines to ensure freedom from bias. Premature reporting of results should be avoided. The bar for clinical benefit should be raised for drug registration, which should require publication and review of mature data from RCTs, post-marketing health outcome studies, and value-based pricing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simplified sleep restriction for insomnia in general practice: a randomised controlled trial.

PubMed

Falloon, Karen; Elley, C Raina; Fernando, Antonio; Lee, Arier C; Arroll, Bruce

2015-08-01

Insomnia is common in primary care. Cognitive behavioural therapy for insomnia (CBT-I) is effective but requires more time than is available in the general practice consultation. Sleep restriction is one behavioural component of CBT-I. To assess whether simplified sleep restriction (SSR) can be effective in improving sleep in primary insomnia. Randomised controlled trial of patients in urban general practice settings in Auckland, New Zealand. Adults with persistent primary insomnia and no mental health or significant comorbidity were eligible. Intervention patients received SSR instructions and sleep hygiene advice. Control patients received sleep hygiene advice alone. Primary outcomes included change in sleep quality at 6 months measured by the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), and sleep efficiency (SE%). The proportion of participants reaching a predefined 'insomnia remission' treatment response was calculated. Ninety-seven patients were randomised and 94 (97%) completed the study. At 6-month follow-up, SSR participants had improved PSQI scores (6.2 versus 8.4, P<0.001), ISI scores (8.6 versus 11.1, P = 0.001), actigraphy-assessed SE% (difference 2.2%, P = 0.006), and reduced fatigue (difference -2.3 units, P = 0.04), compared with controls. SSR produced higher rates of treatment response (67% [28 out of 42] versus 41% [20 out of 49]); number needed to treat = 4 (95% CI = 2.0 to 19.0). Controlling for age, sex, and severity of insomnia, the adjusted odds ratio for insomnia remission was 2.7 (95% CI = 1.1 to 6.5). There were no significant differences in other outcomes or adverse effects. SSR is an effective brief intervention in adults with primary insomnia and no comorbidities, suitable for use in general practice. © British Journal of General Practice 2015.

The clinical and cost-effectiveness of brief advice for excessive alcohol consumption among people attending sexual health clinics: a randomised controlled trial

PubMed Central

Crawford, Mike J; Sanatinia, Rahil; Barrett, Barbara; Byford, Sarah; Dean, Madeleine; Green, John; Jones, Rachael; Leurent, Baptiste; Sweeting, Michael J; Touquet, Robin; Greene, Linda; Tyrer, Peter; Ward, Helen; Lingford-Hughes, Anne

2015-01-01

Objectives To examine the clinical and cost-effectiveness of brief advice for excessive alcohol consumption among people who attend sexual health clinics. Methods Two-arm, parallel group, assessor blind, pragmatic, randomised controlled trial. 802 people aged 19 years or over who attended one of three sexual health clinics and were drinking excessively were randomised to either brief advice or control treatment. Brief advice consisted of feedback on alcohol and health, written information and an offer of an appointment with an Alcohol Health Worker. Control participants received a leaflet on health and lifestyle. The primary outcome was mean weekly alcohol consumption during the previous 90 days measured 6 months after randomisation. The main secondary outcome was unprotected sex during this period. Results Among the 402 randomised to brief advice, 397 (99%) received it. The adjusted mean difference in alcohol consumption at 6 months was −2.33 units per week (95% CI −4.69 to 0.03, p=0.053) among those in the active compared to the control arm of the trial. Unprotected sex was reported by 154 (53%) of those who received brief advice, and 178 (59%) controls (adjusted OR=0.89, 95% CI 0.63 to 1.25, p=0.496). There were no significant differences in costs between study groups at 6 months. Conclusions Introduction of universal screening and brief advice for excessive alcohol use among people attending sexual health clinics does not result in clinically important reductions in alcohol consumption or provide a cost-effective use of resources. Trial registration number Current Controlled Trials ISRCTN 99963322. PMID:24936090

Pressure RElieving Support SUrfaces: a Randomised Evaluation 2 (PRESSURE 2): study protocol for a randomised controlled trial.

PubMed

Brown, Sarah; Smith, Isabelle L; Brown, Julia M; Hulme, Claire; McGinnis, Elizabeth; Stubbs, Nikki; Nelson, E Andrea; Muir, Delia; Rutherford, Claudia; Walker, Kay; Henderson, Valerie; Wilson, Lyn; Gilberts, Rachael; Collier, Howard; Fernandez, Catherine; Hartley, Suzanne; Bhogal, Moninder; Coleman, Susanne; Nixon, Jane E

2016-12-20

Pressure ulcers represent a major burden to patients, carers and the healthcare system, affecting approximately 1 in 17 hospital and 1 in 20 community patients. They impact greatly on an individual's functional status and health-related quality of life. The mainstay of pressure ulcer prevention practice is the provision of pressure redistribution support surfaces and patient repositioning. The aim of the PRESSURE 2 study is to compare the two main mattress types utilised within the NHS: high-specification foam and alternating pressure mattresses, in the prevention of pressure ulcers. PRESSURE 2 is a multicentre, open-label, randomised, double triangular, group sequential, parallel group trial. A maximum of 2954 'high-risk' patients with evidence of acute illness will be randomised on a 1:1 basis to receive either a high-specification foam mattress or alternating-pressure mattress in conjunction with an electric profiling bed frame. The primary objective of the trial is to compare mattresses in terms of the time to developing a new Category 2 or above pressure ulcer by 30 days post end of treatment phase. Secondary endpoints include time to developing new Category 1 and 3 or above pressure ulcers, time to healing of pre-existing Category 2 pressure ulcers, health-related quality of life, cost-effectiveness, incidence of mattress change and safety. Validation objectives are to determine the responsiveness of the Pressure Ulcer Quality of Life-Prevention instrument and the feasibility of having a blinded endpoint assessment using photography. The trial will have a maximum of three planned analyses with unequally spaced reviews at event-driven coherent cut-points. The futility boundaries are constructed as non-binding to allow a decision for stopping early to be overruled by the Data Monitoring and Ethics Committee. The double triangular, group sequential design of the PRESSURE 2 trial will provide an efficient design through the possibility of early stopping for

Promoting smoking cessation in Pakistani and Bangladeshi men in the UK: pilot cluster randomised controlled trial of trained community outreach workers

PubMed Central

2011-01-01

Background Smoking prevalence is high among Pakistani and Bangladeshi men in the UK, but there are few tailored smoking cessation programmes for Pakistani and Bangladeshi communities. The aim of this study was to pilot a cluster randomised controlled trial comparing the effectiveness of Pakistani and Bangladeshi smoking cessation outreach workers with standard care to improve access to and the success of English smoking cessation services. Methods A pilot cluster randomised controlled trial was conducted in Birmingham, UK. Geographical lower layer super output areas were used to identify natural communities where more than 10% of the population were of Pakistani and Bangladeshi origin. 16 agglomerations of super output areas were randomised to normal care controls vs. outreach intervention. The number of people setting quit dates using NHS services, validated abstinence from smoking at four weeks, and stated abstinence at three and six months were assessed. The impact of the intervention on choice and adherence to treatments, attendance at clinic appointments and patient satisfaction were also assessed. Results We were able to randomise geographical areas and deliver the outreach worker-based services. More Pakistani and Bangladeshi men made quit attempts with NHS services in intervention areas compared with control areas, rate ratio (RR) 1.32 (95%CI: 1.03-1.69). There was a small increase in the number of 4-week abstinent smokers in intervention areas (RR 1.30, 95%CI: 0.82-2.06). The proportion of service users attending weekly appointments was lower in intervention areas than control areas. No difference was found between intervention and control areas in choice and adherence to treatments or patient satisfaction with the service. The total cost of the intervention was £124,000; an estimated cost per quality-adjusted life year (QALY) gained of £8,500. Conclusions The intervention proved feasible and acceptable. Outreach workers expanded reach of smoking

The role of cognitive training in endourology: a randomised controlled trial.

PubMed

Shah, M; Aydin, A; Moran, A; Khan, M S; Dasgupta, P; Ahmed, K

2018-04-01

Cognitive training is an important training modality which allows the user to rehearse a procedure without physically carrying it out. This has led to recent interests to incorporate cognitive training within surgical education but research is currently limited. The use of cognitive training in surgery is not clear-cut and so this study aimed to determine whether, relative to a control condition, the use of cognitive training improves technical surgical skills on a ureteroscopy simulator, and if so whether one cognitive training method is superior. This prospective, comparative study recruited 59 medical students and randomised them to one of three groups: control- simulation training only (n=20), flashcards cognitive training group (n=20) or mental imagery cognitive training group (n=19). All participants completed three tasks at baseline on the URO Mentor simulator followed by the cognitive intervention if randomised to receive it. Participants then returned to perform an assessment task on the simulator. Outcome measures from the URO Mentor performance report was used for analysis and a quantitative survey was given to all participants to assess usefulness of training received. This study showed cognitive training to have minimal effects on technical skills of participants. The mental imagery group had fewer laser misfires in the assessment task when compared to both control and flashcards group (P=.017, P=.036, respectively). The flashcards group rated their preparation to be most useful when compared to control (P=.0125). Other parameters analysed between the groups did not reach statistical significance. Cognitive training was found to be feasible and cost effective when carried out in addition to simulation training. This study has shown that the role of cognitive training within acquisition of surgical skills is minimal and that no form of cognitive training was superior to another. Further research needs to be done to evaluate other ways of performing

Digital robust control law synthesis using constrained optimization

NASA Technical Reports Server (NTRS)

Mukhopadhyay, Vivekananda

1989-01-01

Development of digital robust control laws for active control of high performance flexible aircraft and large space structures is a research area of significant practical importance. The flexible system is typically modeled by a large order state space system of equations in order to accurately represent the dynamics. The active control law must satisy multiple conflicting design requirements and maintain certain stability margins, yet should be simple enough to be implementable on an onboard digital computer. Described here is an application of a generic digital control law synthesis procedure for such a system, using optimal control theory and constrained optimization technique. A linear quadratic Gaussian type cost function is minimized by updating the free parameters of the digital control law, while trying to satisfy a set of constraints on the design loads, responses and stability margins. Analytical expressions for the gradients of the cost function and the constraints with respect to the control law design variables are used to facilitate rapid numerical convergence. These gradients can be used for sensitivity study and may be integrated into a simultaneous structure and control optimization scheme.

Representation of People with Intellectual Disabilities in Randomised Controlled Trials on Antipsychotic Treatment for Behavioural Problems

ERIC Educational Resources Information Center

Scheifes, A.; Stolker, J. J.; Egberts, A. C. G.; Nijman, H. L. I.; Heerdink, E. R.

2011-01-01

Background: Behavioural problems are common in people with intellectual disability (ID) and are often treated with antipsychotics. Aim: To establish the frequency and characteristics of people with ID included in randomised controlled trials (RCTs) on antipsychotic treatment for behavioural problems, and to investigate the quality of these RCTs.…

Safety and efficacy of antibiotics compared with appendicectomy for treatment of uncomplicated acute appendicitis: meta-analysis of randomised controlled trials

PubMed Central

Varadhan, Krishna K; Neal, Keith R

2012-01-01

Objective To compare the safety and efficacy of antibiotic treatment versus appendicectomy for the primary treatment of uncomplicated acute appendicitis. Design Meta-analysis of randomised controlled trials. Population Randomised controlled trials of adult patients presenting with uncomplicated acute appendicitis, diagnosed by haematological and radiological investigations. Interventions Antibiotic treatment versus appendicectomy. Outcome measures The primary outcome measure was complications. The secondary outcome measures were efficacy of treatment, length of stay, and incidence of complicated appendicitis and readmissions. Results Four randomised controlled trials with a total of 900 patients (470 antibiotic treatment, 430 appendicectomy) met the inclusion criteria. Antibiotic treatment was associated with a 63% (277/438) success rate at one year. Meta-analysis of complications showed a relative risk reduction of 31% for antibiotic treatment compared with appendicectomy (risk ratio (Mantel-Haenszel, fixed) 0.69 (95% confidence interval 0.54 to 0.89); I2=0%; P=0.004). A secondary analysis, excluding the study with crossover of patients between the two interventions after randomisation, showed a significant relative risk reduction of 39% for antibiotic therapy (risk ratio 0.61 (0.40 to 0.92); I2=0%; P=0.02). Of the 65 (20%) patients who had appendicectomy after readmission, nine had perforated appendicitis and four had gangrenous appendicitis. No significant differences were seen for treatment efficacy, length of stay, or risk of developing complicated appendicitis. Conclusion Antibiotics are both effective and safe as primary treatment for patients with uncomplicated acute appendicitis. Initial antibiotic treatment merits consideration as a primary treatment option for early uncomplicated appendicitis. PMID:22491789

Subcallosal cingulate deep brain stimulation for treatment-resistant depression: a multisite, randomised, sham-controlled trial.

PubMed

Holtzheimer, Paul E; Husain, Mustafa M; Lisanby, Sarah H; Taylor, Stephan F; Whitworth, Louis A; McClintock, Shawn; Slavin, Konstantin V; Berman, Joshua; McKhann, Guy M; Patil, Parag G; Rittberg, Barry R; Abosch, Aviva; Pandurangi, Ananda K; Holloway, Kathryn L; Lam, Raymond W; Honey, Christopher R; Neimat, Joseph S; Henderson, Jaimie M; DeBattista, Charles; Rothschild, Anthony J; Pilitsis, Julie G; Espinoza, Randall T; Petrides, Georgios; Mogilner, Alon Y; Matthews, Keith; Peichel, DeLea; Gross, Robert E; Hamani, Clement; Lozano, Andres M; Mayberg, Helen S

2017-11-01

Deep brain stimulation (DBS) of the subcallosal cingulate white matter has shown promise as an intervention for patients with chronic, unremitting depression. To test the safety and efficacy of DBS for treatment-resistant depression, a prospective, randomised, sham-controlled trial was conducted. Participants with treatment-resistant depression were implanted with a DBS system targeting bilateral subcallosal cingulate white matter and randomised to 6 months of active or sham DBS, followed by 6 months of open-label subcallosal cingulate DBS. Randomisation was computer generated with a block size of three at each site before the site started the study. The primary outcome was frequency of response (defined as a 40% or greater reduction in depression severity from baseline) averaged over months 4-6 of the double-blind phase. A futility analysis was performed when approximately half of the proposed sample received DBS implantation and completed the double-blind phase. At the conclusion of the 12-month study, a subset of patients were followed up for up to 24 months. The study is registered at ClinicalTrials.gov, number NCT00617162. Before the futility analysis, 90 participants were randomly assigned to active (n=60) or sham (n=30) stimulation between April 10, 2008, and Nov 21, 2012. Both groups showed improvement, but there was no statistically significant difference in response during the double-blind, sham-controlled phase (12 [20%] patients in the stimulation group vs five [17%] patients in the control group). 28 patients experienced 40 serious adverse events; eight of these (in seven patients) were deemed to be related to the study device or surgery. This study confirmed the safety and feasibility of subcallosal cingulate DBS as a treatment for treatment-resistant depression but did not show statistically significant antidepressant efficacy in a 6-month double-blind, sham-controlled trial. Future studies are needed to investigate factors such as clinical features

Infant adiposity following a randomised controlled trial of a behavioural intervention in obese pregnancy

PubMed Central

Patel, Nashita; Godfrey, Keith M.; Pasupathy, Dharmintra; Levin, Julia; Flynn, Angela C; Hayes, Louise; Briley, Annette L; Bell, Ruth; Lawlor, Debbie A; Oteng-Ntim, Eugene; Nelson, Scott M.; Robson, Stephen C.; Sattar, Naveed; Singh, Claire; Wardle, Jane; White, Sara; Seed, Paul T; Poston, Lucilla

2017-01-01

Objective Randomised controlled trials are required to address causality in the reported associations between maternal influences and offspring adiposity. The aim of this study was to determine whether an antenatal lifestyle intervention in obese pregnant women associated with improved maternal diet and reduced gestational weight gain leads to a reduction in infant adiposity and sustained improvements in maternal lifestyle behaviours at 6 months postpartum. Subjects and Methods We conducted a planned postnatal follow up of a randomised controlled trial (UPBEAT) of a complex behavioural intervention targeting maternal diet (glycemic load and saturated fat intake) and physical activity in 1555 obese pregnant women. The main outcome measure was infant adiposity, assessed by subscapular and triceps skinfold thicknesses. Maternal diet and physical activity, indices of the familial lifestyle environment, were assessed by questionnaire. Results 698 (45.9%) infants (342 intervention, 356 standard antenatal care) were followed up at mean age 5.92 months. There was no difference in triceps skinfold thickness z-scores between the intervention vs. standard care arms (difference -0.14 SD, 95% CI -0.38 to 0.10, p=0.246), but subscapular skinfold thickness z-score was 0.26 SD (-0.49 to -0.02; p=0.03) lower in the intervention arm. Maternal dietary glycemic load (-35.34; -48.0 to -22.67; p<0.001) and saturated fat intake (-1.93% energy; -2.64 to -1.22; p<0.001) were reduced in the intervention arm at 6 months postpartum. Causal mediation analysis suggested that lower infant subscapular skinfold thickness was mediated by changes in antenatal maternal diet and gestational weight gain rather than postnatal diet. Conclusion This study provides evidence from follow-up of a randomised controlled trial that a maternal behavioural intervention in obese pregnant women has the potential to reduce infant adiposity and to produce a sustained improvement in maternal diet at 6 months postpartum

Optimal strategy analysis based on robust predictive control for inventory system with random demand

NASA Astrophysics Data System (ADS)

Saputra, Aditya; Widowati, Sutrisno

2017-12-01

In this paper, the optimal strategy for a single product single supplier inventory system with random demand is analyzed by using robust predictive control with additive random parameter. We formulate the dynamical system of this system as a linear state space with additive random parameter. To determine and analyze the optimal strategy for the given inventory system, we use robust predictive control approach which gives the optimal strategy i.e. the optimal product volume that should be purchased from the supplier for each time period so that the expected cost is minimal. A numerical simulation is performed with some generated random inventory data. We simulate in MATLAB software where the inventory level must be controlled as close as possible to a set point decided by us. From the results, robust predictive control model provides the optimal strategy i.e. the optimal product volume that should be purchased and the inventory level was followed the given set point.