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Sample records for robust randomised controlled

  1. Patient-reported outcomes in randomised controlled trials of colorectal cancer: an analysis determining the availability of robust data to inform clinical decision-making

    PubMed Central

    Whale, Katie; Fish, Daniel; Fayers, Peter; Cafaro, Valentina; Pusic, Andrea; Blazeby, Jane M.; Efficace, Fabio

    2016-01-01

    Purpose Randomised controlled trials (RCTs) are the most robust study design measuring outcomes of colorectal cancer (CRC) treatments, but to influence clinical practice trial design and reporting of patient-reported outcomes (PROs) must be of high quality. Objectives of this study were as follows: to examine the quality of PRO reporting in RCTs of CRC treatment; to assess the availability of robust data to inform clinical decision-making; and to investigate whether quality of reporting improved over time. Methods A systematic review from January 2004–February 2012 identified RCTs of CRC treatment describing PROs. Relevant abstracts were screened and manuscripts obtained. Methodological quality was assessed using International Society for Quality of Life Research—patient-reported outcome reporting standards. Changes in reporting quality over time were established by comparison with previous data, and risk of bias was assessed with the Cochrane risk of bias tool. Results Sixty-six RCTs were identified, seven studies (10 %) reported survival benefit favouring the experimental treatment, 35 trials (53 %) identified differences in PROs between treatment groups, and the clinical significance of these differences was discussed in 19 studies (29 %). The most commonly reported treatment type was chemotherapy (n = 45; 68 %). Improvements over time in key methodological issues including the documentation of missing data and the discussion of the clinical significance of PROs were found. Thirteen trials (20 %) had high-quality reporting. Conclusions Whilst improvements in PRO quality reporting over time were found, several recent studies still fail to robustly inform clinical practice. Quality of PRO reporting must continue to improve to maximise the clinical impact of PRO findings. PMID:25910987

  2. Synthesis of robust controllers

    NASA Technical Reports Server (NTRS)

    Marrison, Chris

    1993-01-01

    At the 1990 American Controls Conference a benchmark problem was issued as a challenge for designing robust compensators. Many compensators were presented in response to the problem. In previous work Stochastic Robustness Analysis (SRA) was used to compare these compensators. In this work SRA metrics are used as guides to synthesize robust compensators, using the benchmark problem as an example.

  3. Robust Adaptive Control

    NASA Technical Reports Server (NTRS)

    Narendra, K. S.; Annaswamy, A. M.

    1985-01-01

    Several concepts and results in robust adaptive control are are discussed and is organized in three parts. The first part surveys existing algorithms. Different formulations of the problem and theoretical solutions that have been suggested are reviewed here. The second part contains new results related to the role of persistent excitation in robust adaptive systems and the use of hybrid control to improve robustness. In the third part promising new areas for future research are suggested which combine different approaches currently known.

  4. Robust Control Systems.

    DTIC Science & Technology

    1981-12-01

    Controller ................... 38 Sampled-Data Performance Analysis ............. 44 Doyle and Stein Technique in Discrete-Time Systems - 1...48 Doyle and Stein Technique in Discretd-Time System.s - 2 ................................. 50 Enhancing Robustness of... Technique Extended to Sampled-Data Controllers ................ 73 G715 Robustness Enhancement by Directly D"?C TAB E

  5. Robust control for uncertain structures

    NASA Technical Reports Server (NTRS)

    Douglas, Joel; Athans, Michael

    1991-01-01

    Viewgraphs on robust control for uncertain structures are presented. Topics covered include: robust linear quadratic regulator (RLQR) formulas; mismatched LQR design; RLQR design; interpretations of RLQR design; disturbance rejection; and performance comparisons: RLQR vs. mismatched LQR.

  6. Supported employment: randomised controlled trial*

    PubMed Central

    Howard, Louise M.; Heslin, Margaret; Leese, Morven; McCrone, Paul; Rice, Christopher; Jarrett, Manuela; Spokes, Terry; Huxley, Peter; Thornicroft, Graham

    2010-01-01

    Background There is evidence from North American trials that supported employment using the individual placement and support (IPS) model is effective in helping individuals with severe mental illness gain competitive employment. There have been few trials in other parts of the world. Aims To investigate the effectiveness and cost-effectiveness of IPS in the UK. Method Individuals with severe mental illness in South London were randomised to IPS or local traditional vocational services (treatment as usual) (ISRCTN96677673). Results Two hundred and nineteen participants were randomised, and 90% assessed 1 year later. There were no significant differences between the treatment as usual and intervention groups in obtaining competitive employment (13% in the intervention group and 7% in controls; risk ratio 1.35, 95% CI 0.95–1.93, P = 0.15), nor in secondary outcomes. Conclusions There was no evidence that IPS was of significant benefit in achieving competitive employment for individuals in South London at 1-year follow-up, which may reflect suboptimal implementation. Implementation of IPS can be challenging in the UK context where IPS is not structurally integrated with mental health services, and economic disincentives may lead to lower levels of motivation in individuals with severe mental illness and psychiatric professionals. PMID:20435968

  7. Robust Control Feedback and Learning

    DTIC Science & Technology

    2002-11-30

    98-1-0026 5b. GRANT NUMBER Robust Control, Feedback and Learning F49620-98-1-0026 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Michael G...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 Final Report: ROBUST CONTROL FEEDBACK AND LEARNING AFOSR Grant F49620-98-1-0026 October 1...Philadelphia, PA, 2000. [16] M. G. Safonov. Recent advances in robust control, feedback and learning . In S. 0. R. Moheimani, editor, Perspectives in Robust

  8. Robust controls with structured perturbations

    NASA Technical Reports Server (NTRS)

    Keel, Leehyun

    1993-01-01

    This final report summarizes the recent results obtained by the principal investigator and his coworkers on the robust stability and control of systems containing parametric uncertainty. The starting point is a generalization of Kharitonov's theorem obtained in 1989, and its generalization to the multilinear case, the singling out of extremal stability subsets, and other ramifications now constitutes an extensive and coherent theory of robust parametric stability that is summarized in the results contained here.

  9. Designing robust control laws using genetic algorithms

    NASA Technical Reports Server (NTRS)

    Marrison, Chris

    1994-01-01

    The purpose of this research is to create a method of finding practical, robust control laws. The robustness of a controller is judged by Stochastic Robustness metrics and the level of robustness is optimized by searching for design parameters that minimize a robustness cost function.

  10. Robust flight control of rotorcraft

    NASA Astrophysics Data System (ADS)

    Pechner, Adam Daniel

    With recent design improvement in fixed wing aircraft, there has been a considerable interest in the design of robust flight control systems to compensate for the inherent instability necessary to achieve desired performance. Such systems are designed for maximum available retention of stability and performance in the presence of significant vehicle damage or system failure. The rotorcraft industry has shown similar interest in adopting these reconfigurable flight control schemes specifically because of their ability to reject disturbance inputs and provide a significant amount of robustness for all but the most catastrophic of situations. The research summarized herein focuses on the extension of the pseudo-sliding mode control design procedure interpreted in the frequency domain. Application of the technique is employed and simulated on two well known helicopters, a simplified model of a hovering Sikorsky S-61 and the military's Black Hawk UH-60A also produced by Sikorsky. The Sikorsky helicopter model details are readily available and was chosen because it can be limited to pitch and roll motion reducing the number of degrees of freedom and yet contains two degrees of freedom, which is the minimum requirement in proving the validity of the pseudo-sliding control technique. The full order model of a hovering Black Hawk system was included both as a comparison to the S-61 helicopter design system and as a means to demonstrate the scaleability and effectiveness of the control technique on sophisticated systems where design robustness is of critical concern.

  11. 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.

  12. Razors versus clippers. A randomised controlled trial.

    PubMed

    Taylor, Tracy; Tanner, Judith

    2005-12-01

    The purpose of this randomised controlled trial was to determine if patients showed a preference for preoperative hair removal with razors or clippers and to identify if one method was associated with more trauma or postoperative infections. The trial took place in a day surgery unit with patients who were having a range of surgical procedures including hernias and varicose veins. This study was sponsored by an award from the NATN/3M Clinical Fellowship.

  13. Robust Fixed-Structure Controller Synthesis

    NASA Technical Reports Server (NTRS)

    Corrado, Joseph R.; Haddad, Wassim M.; Gupta, Kajal (Technical Monitor)

    2000-01-01

    The ability to develop an integrated control system design methodology for robust high performance controllers satisfying multiple design criteria and real world hardware constraints constitutes a challenging task. The increasingly stringent performance specifications required for controlling such systems necessitates a trade-off between controller complexity and robustness. The principle challenge of the minimal complexity robust control design is to arrive at a tractable control design formulation in spite of the extreme complexity of such systems. Hence, design of minimal complexitY robust controllers for systems in the face of modeling errors has been a major preoccupation of system and control theorists and practitioners for the past several decades.

  14. Implementing Randomised Control Trials in Open and Distance Learning: A Feasibility Study

    ERIC Educational Resources Information Center

    Herodotou, Christothea; Heiser, Sarah; Rienties, Bart

    2017-01-01

    Randomised control trials (RCTs) are an evidence-based research approach which has not yet been adopted and widely used in open and distance education to inform educational policy and practice. Despite the challenges entailed in their application, RCTs hold the power to robustly evaluate the effects of educational interventions in distance…

  15. Robust Controller Design for Hemispherical Resonator Gyroscope

    DTIC Science & Technology

    2011-11-01

    f v Figure 1. Operating principle of HRG Robust Controller Design for Hemispherical Resonator Gyroscope Chul Hyun1), Byung ...Petersburg, Russia.: 26-34 4) Chul Hyun. 2011. Design of Robust Digital Controller for Hemispherical Resonator Gyroscopes, Ph.D. dissertation, Seoul

  16. The Internet and randomised controlled trials.

    PubMed

    Kelly, M A; Oldham, J

    1997-11-01

    Several factors constrain the implementation of Randomised Controlled Trials (RCTs). To obtain large sample sizes a multicentred multinational trial may be necessary or a long sampling period. The larger the trial the larger is the unit cost. To allow larger sample sizes, shorter sampling periods and lower unit costs, new methods are needed. The Internet and in particular the WWW provides such an opportunity. The WWW can provide global access, fast interaction and automation. A prototype Internet Trials Service (ITS) is currently being tested with a real international clinical trial (the Growth Restriction Intervention Trial--GRIT). The ITS is hosted on a Web server. It provides a series of HTML documents that describe the GRIT protocol. Registered centres may enter patients into the GRIT trial via ITS. Java applets are used to collect trial data before returning the study number and randomisation. ITS assumes all trial data will be intercepted by a sniffer. Therefore no information is sent that could specifically identify a patient, this must be sent later by more secure means. ITS assumes that trial centres can be spoofed. To authenticate the patients entered into the trial and the trial data sent, a regular audit report is sent to each centre by secure means for confirmation. By using Java, a full functional data entry system can be developed that runs locally within any Java enabled browser. It can perform data validation locally and also provide a sophisticated user interface.

  17. Robust Multiobjective Controllability of Complex Neuronal Networks.

    PubMed

    Tang, Yang; Gao, Huijun; Du, Wei; Lu, Jianquan; Vasilakos, Athanasios V; Kurths, Jurgen

    2016-01-01

    This paper addresses robust multiobjective identification of driver nodes in the neuronal network of a cat's brain, in which uncertainties in determination of driver nodes and control gains are considered. A framework for robust multiobjective controllability is proposed by introducing interval uncertainties and optimization algorithms. By appropriate definitions of robust multiobjective controllability, a robust nondominated sorting adaptive differential evolution (NSJaDE) is presented by means of the nondominated sorting mechanism and the adaptive differential evolution (JaDE). The simulation experimental results illustrate the satisfactory performance of NSJaDE for robust multiobjective controllability, in comparison with six statistical methods and two multiobjective evolutionary algorithms (MOEAs): nondominated sorting genetic algorithms II (NSGA-II) and nondominated sorting composite differential evolution. It is revealed that the existence of uncertainties in choosing driver nodes and designing control gains heavily affects the controllability of neuronal networks. We also unveil that driver nodes play a more drastic role than control gains in robust controllability. The developed NSJaDE and obtained results will shed light on the understanding of robustness in controlling realistic complex networks such as transportation networks, power grid networks, biological networks, etc.

  18. 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.

  19. Active robust vibration control of flexible structures

    NASA Astrophysics Data System (ADS)

    Hu, Yan-Ru; Ng, Alfred

    2005-11-01

    Flexible structures are extensively used in many space applications, for example, space-based radar antennae, space robotic systems, and space station, etc. The flexibility of these space structures results in problems of structural vibration and shape deformation, etc. In recent years, active control methods have been developed to suppress structural vibration and improve the performance of these flexible space structures. In this paper, we developed an approach for active vibration control of flexible structures with integrated piezoelectric actuators using control theory. First, dynamic models for a flexible circular plate with integrated piezoelectric actuators and sensors are derived using the Rayleigh-Ritz method. An active robust controller is designed to suppress vibration of the circular plate. Robustness of the control system of the circular plate is discussed for the model parameter uncertainty. This active robust vibration control method is tested via experimental implementation. The experimental results show that the proposed robust active control method is efficient for active vibration suppression.

  20. 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

  1. Robust LQR control for the benchmark problem

    NASA Technical Reports Server (NTRS)

    Douglas, Joel; Athans, Michael

    1991-01-01

    An examination is made of the performance of a linear quadratic regulator which is robust to parametric uncertainty. The controller, which feeds back all states, is based upon Petersen's approach. Simulations show, using the benchmark problem, that remarkable performance robustness can be achieved.

  2. 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.

  3. Modeling and robust control of wind turbine

    NASA Astrophysics Data System (ADS)

    Gilev, Bogdan

    2016-12-01

    In this paper a model of a wind turbine is evaluated, consisting of: wind speed model, mechanical and electrical model of generator and tower oscillation model. This model is linearized around of a nominal point. By using the linear model with uncertainties is synthesized a uncertain model. By using the uncertain model and robust control theory is developed a robust controller, which provide mode of stabilizing the rotor frequency and damping the tower oscillations. Finally is simulated work of nonlinear system and robust controller

  4. Robust lateral control of highway vehicles

    SciTech Connect

    Byrne, R.H.; Abdallah, C.

    1994-08-01

    Vehicle lateral dynamics are affected by vehicle mass, longitudinal velocity, vehicle inertia, and the cornering stiffness of the tires. All of these parameters are subject to variation, even over the course of a single trip. Therefore, a practical lateral control system must guarantee stability, and hopefully ride comfort, over a wide range of parameter changes. This paper describes a robust controller which theoretically guarantees stability over a wide range of parameter changes. The robust controller is designed using a frequency domain transfer function approach. An uncertainty band in the frequency domain is determined using simulations over the range of expected parameter variations. Based on this bound, a robust controller is designed by solving the Nevanlinna-Pick interpolation problem. The performance of the robust controller is then evaluated over the range of parameter variations through simulations.

  5. Experimental Robust Control of Structural Acoustic Radiation

    NASA Technical Reports Server (NTRS)

    Cox, David E.; Gibbs, Gary P.; Clark, Robert L.; Vipperman, Jeffrey S.

    1998-01-01

    This work addresses the design and application of robust controllers for structural acoustic control. Both simulation and experimental results are presented. H(infinity) and mu-synthesis design methods were used to design feedback controllers which minimize power radiated from a panel while avoiding instability due to unmodeled dynamics. Specifically, high order structural modes which couple strongly to the actuator-sensor path were poorly modeled. This model error was analytically bounded with an uncertainty model, which allowed controllers to be designed without artificial limits on control effort. It is found that robust control methods provide the control designer with physically meaningful parameters with which to tune control designs and can be very useful in determining limits of performance. Experimental results also showed, however, poor robustness properties for control designs with ad-hoc uncertainty models. The importance of quantifying and bounding model errors is discussed.

  6. Adaptive Critic Nonlinear Robust Control: A Survey.

    PubMed

    Wang, Ding; He, Haibo; Liu, Derong

    2017-10-01

    Adaptive dynamic programming (ADP) and reinforcement learning are quite relevant to each other when performing intelligent optimization. They are both regarded as promising methods involving important components of evaluation and improvement, at the background of information technology, such as artificial intelligence, big data, and deep learning. Although great progresses have been achieved and surveyed when addressing nonlinear optimal control problems, the research on robustness of ADP-based control strategies under uncertain environment has not been fully summarized. Hence, this survey reviews the recent main results of adaptive-critic-based robust control design of continuous-time nonlinear systems. The ADP-based nonlinear optimal regulation is reviewed, followed by robust stabilization of nonlinear systems with matched uncertainties, guaranteed cost control design of unmatched plants, and decentralized stabilization of interconnected systems. Additionally, further comprehensive discussions are presented, including event-based robust control design, improvement of the critic learning rule, nonlinear H∞ control design, and several notes on future perspectives. By applying the ADP-based optimal and robust control methods to a practical power system and an overhead crane plant, two typical examples are provided to verify the effectiveness of theoretical results. Overall, this survey is beneficial to promote the development of adaptive critic control methods with robustness guarantee and the construction of higher level intelligent systems.

  7. Robust Fuzzy Controllers Using FPGAs

    NASA Technical Reports Server (NTRS)

    Monroe, Author Gene S., Jr.

    2007-01-01

    Electro-mechanical device controllers typically come in one of three forms, proportional (P), Proportional Derivative (PD), and Proportional Integral Derivative (PID). Two methods of control are discussed in this paper; they are (1) the classical technique that requires an in-depth mathematical use of poles and zeros, and (2) the fuzzy logic (FL) technique that is similar to the way humans think and make decisions. FL controllers are used in multiple industries; examples include control engineering, computer vision, pattern recognition, statistics, and data analysis. Presented is a study on the development of a PD motor controller written in very high speed hardware description language (VHDL), and implemented in FL. Four distinct abstractions compose the FL controller, they are the fuzzifier, the rule-base, the fuzzy inference system (FIS), and the defuzzifier. FL is similar to, but different from, Boolean logic; where the output value may be equal to 0 or 1, but it could also be equal to any decimal value between them. This controller is unique because of its VHDL implementation, which uses integer mathematics. To compensate for VHDL's inability to synthesis floating point numbers, a scale factor equal to 10(sup (N/4) is utilized; where N is equal to data word size. The scaling factor shifts the decimal digits to the left of the decimal point for increased precision. PD controllers are ideal for use with servo motors, where position control is effective. This paper discusses control methods for motion-base platforms where a constant velocity equivalent to a spectral resolution of 0.25 cm(exp -1) is required; however, the control capability of this controller extends to various other platforms.

  8. Applications of robust control theory - Educational implications

    NASA Technical Reports Server (NTRS)

    Dorato, P.; Yedavalli, R. K.

    1992-01-01

    A survey is made of applications of robust control theory to problems of flight control, control of flexible space structures, and engine control which have appeared in recent conferences and journals. An analysis is made of which theoretical techniques are most commonly used and what implications this has for graduate and undergraduate education in aerospace engineering.

  9. Robust fixed-structure controller synthesis

    NASA Astrophysics Data System (ADS)

    Corrado, Joseph Ralph

    2000-10-01

    The ability to develop an integrated control system design methodology for robust high performance controllers satisfying multiple design criteria and real world hardware constraints constitutes a challenging task. The increasingly stringent performance specifications required for controlling such systems necessitates a trade-off between controller complexity and robustness. The principle challenge of the minimal complexity robust control design is to arrive at a tractable control design formulation in spite of the extreme complexity of such systems. Hence, design of minimal complexity robust controllers for systems in the face of modeling errors has been a major preoccupation of system and control theorists and practitioners for the past several decades. Although the theory for designing linear output feedback controllers is quite mature, the actual solution of the design equations can be a daunting task. This becomes even more difficult if an optimal reduced-order controller is sought. In this dissertation, we develop a general fixed-structure control design framework that addresses the following paradigm: Minimize control law complexity subject to the achievement of a specified accuracy in the face of a specified level of uncertainty. The control law complexity is minimized by developing a decentralized static output feedback formulation for fixed-structure controller synthesis. The decentralized static output feedback formulation captures a large class of controller architectures within a common framework and allows a common numerical algorithm to be used for computational purposes.

  10. Writing to patients: a randomised controlled trial.

    PubMed

    O'Reilly, Máire; Cahill, Mary R; Perry, Ivan J

    2006-01-01

    It has been suggested that consultants should consider writing directly to patients with a summary of their outpatient consultation. In a controlled trial involving consecutive new referrals to a haematology outpatient clinic, we randomised patients to receive either a personal letter from their consultant summarising their consultation (n = 77) or a brief note thanking them for attending the clinic (n = 73). Patients were assessed for recall of and satisfaction with the consultation by a single independent observer, using standardised methods. At the second visit to outpatients, the patients' median percentage recall of items discussed during the consultation was 67% (IQ range 50-80%) in the intervention group, versus 57% (IQ range 43-76%) in the control group (p = 0.3). Strongly positive views on the personal letter were expressed by patients and referring clinicians. The findings suggest that although personal letters do not substantially improve recall of the clinical encounter, they are feasible, highly valued by patients and acceptable to referring clinicians.

  11. Robust Reachability of Boolean Control Networks.

    PubMed

    Li, Fangfei; Tang, Yang

    2016-04-20

    Boolean networks serve a powerful tool in analysis of genetic regulatory networks since it emphasizes the fundamental principles and establishes a nature framework for capturing the dynamics of regulation of cellular states. In this paper, the robust reachability of Boolean control networks is investigated by means of semi-tensor product. Necessary and sufficient conditions for the robust reachability of Boolean control networks are provided, in which control inputs relying on disturbances or not are considered, respectively. Besides, the corresponding control algorithms are developed for these two cases. A reduced model of the lac operon in the Escherichia coli is presented to show the effectiveness of the presented results.

  12. Robust control for large space antennas

    NASA Technical Reports Server (NTRS)

    Barrett, M. F.

    1987-01-01

    A brief description of program objectives and the space based radar application is given. General characteristics of the 100 m diameter reflector spacecraft are described along with the intended mission and associated requirements, and dynamic characteristics relevant to that mission. Preliminary control analyses are carried out for the critical rapid slew and settle maneuver to establish feedback control requirements and fundamental limitations in meeting those requirements with control hardware for a baseline reaction control system (RCS) jet placement assumed for the open loop bang-bang slew limitations. Control moment gyros (CMGs), angular position sensors, and linear translation sensors are placed for feedback control. Control laws are designed for the improved sensor and actuator placement and evaluated for performance and robustness to unstructured model uncertainty. The robustness of the control design is assessed with respect to modal parameter uncertainty. Results of the control designs analyses are summarized, conclusions are drawn, and recommendations made for future studies.

  13. 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.

  14. Principals' Pupil Control Behavior and School Robustness.

    ERIC Educational Resources Information Center

    Smedley, Stanley R.; Willower, Donald J.

    1981-01-01

    A survey of 3,100 students, teachers, and principals in 47 elementary and secondary schools in the Middle Atlantic region, using the Pupil Control Behavior Form, revealed a positive association between principals' humanistic pupil control behavior and schools'"robustness" (the degree of meaning and excitement students find in school).…

  15. Robustness of network controllability in cascading failure

    NASA Astrophysics Data System (ADS)

    Chen, Shi-Ming; Xu, Yun-Fei; Nie, Sen

    2017-04-01

    It is demonstrated that controlling complex networks in practice needs more inputs than that predicted by the structural controllability framework. Besides, considering the networks usually faces to the external or internal failure, we define parameters to evaluate the control cost and the variation of controllability after cascades, exploring the effect of number of control inputs on the controllability for random networks and scale-free networks in the process of cascading failure. For different topological networks, the results show that the robustness of controllability will be stronger through allocating different control inputs and edge capacity.

  16. 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.

  17. Average-cost based robust structural control

    NASA Technical Reports Server (NTRS)

    Hagood, Nesbitt W.

    1993-01-01

    A method is presented for the synthesis of robust controllers for linear time invariant structural systems with parameterized uncertainty. The method involves minimizing quantities related to the quadratic cost (H2-norm) averaged over a set of systems described by real parameters such as natural frequencies and modal residues. Bounded average cost is shown to imply stability over the set of systems. Approximations for the exact average are derived and proposed as cost functionals. The properties of these approximate average cost functionals are established. The exact average and approximate average cost functionals are used to derive dynamic controllers which can provide stability robustness. The robustness properties of these controllers are demonstrated in illustrative numerical examples and tested in a simple SISO experiment on the MIT multi-point alignment testbed.

  18. Structurally robust control of complex networks

    NASA Astrophysics Data System (ADS)

    Nacher, Jose C.; Akutsu, Tatsuya

    2015-01-01

    Robust control theory has been successfully applied to numerous real-world problems using a small set of devices called controllers. However, the real systems represented by networks contain unreliable components and modern robust control engineering has not addressed the problem of structural changes on complex networks including scale-free topologies. Here, we introduce the concept of structurally robust control of complex networks and provide a concrete example using an algorithmic framework that is widely applied in engineering. The developed analytical tools, computer simulations, and real network analyses lead herein to the discovery that robust control can be achieved in scale-free networks with exactly the same order of controllers required in a standard nonrobust configuration by adjusting only the minimum degree. The presented methodology also addresses the probabilistic failure of links in real systems, such as neural synaptic unreliability in Caenorhabditis elegans, and suggests a new direction to pursue in studies of complex networks in which control theory has a role.

  19. Parametric Uncertainty Reduction in Robust Multivariable Control

    DTIC Science & Technology

    1993-09-01

    presents a method for reducing the Dumber of parametric un- certainties used in the design of a robust Ho, controller. The resulting controller is shown...determining robust stability can be de- duced from Figure 2.9. Stability in the loop containing the perturbation requires that for all frequencies det {I... det (I + MA) = 01 {minAEA(a(A) I det (J + MA) = 0)1’ otherwise 15 It can be shown that the SSV has the following properties (Doyle, 1982): 1. F(oM) =1

  20. Robust Adaptive Control of Hypnosis During Anesthesia

    DTIC Science & Technology

    2007-11-02

    1 of 4 ROBUST ADAPTIVE CONTROL OF HYPNOSIS DURING ANESTHESIA Pascal Grieder1, Andrea Gentilini1, Manfred Morari1, Thomas W. Schnider2 1ETH Zentrum...A closed-loop controller for hypnosis was designed and validated on humans at our laboratory. The controller aims at regulat- ing the Bispectral Index...BIS) - a surro- gate measure of hypnosis derived from the electroencephalogram of the patient - with the volatile anesthetic isoflurane administered

  1. 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.

  2. Robust control algorithms for Mars aerobraking

    NASA Astrophysics Data System (ADS)

    Shipley, Buford W., Jr.; Ward, Donald T.

    Four atmospheric guidance concepts have been adapted to control an interplanetary vehicle aerobraking in the Martian atmosphere. The first two offer improvements to the Analytic Predictor Corrector (APC) to increase its robustness to density variations. The second two are variations of a new Liapunov tracking exit phase algorithm, developed to guide the vehicle along a reference trajectory. These four new controllers are tested using a six degree of freedom computer simulation to evaluate their robustness. MARSGRAM is used to develop realistic atmospheres for the study. When square wave density pulses perturb the atmosphere all four controllers are successful. The algorithms are tested against atmospheres where the inbound and outbound density functions are different. Square wave density pulses are again used, but only for the outbound leg of the trajectory. Additionally, sine waves are used to perturb the density function. The new algorithms are found to be more robust than any previously tested and a Liapunov controller is selected as the most robust control algorithm overall examined.

  3. 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…

  4. Robust multivariable controller design for flexible spacecraft

    NASA Technical Reports Server (NTRS)

    Joshi, Suresh M.; Armstrong, Ernest S.

    1986-01-01

    Large, flexible spacecraft are typically characterized by a large number of significant elastic modes with very small inherent damping, low, closely spaced natural frequencies, and the lack of accurate knowledge of the structural parameters. Summarized here is some recent research on the design of robust controllers for such spacecraft, which will maintain stability, and possible performance, despite these problems. Two types of controllers are considered, the first being the linear-quadratic-Gaussian-(LQG)-type. The second type utilizes output feedback using collocated sensors and actuators. The problem of designing robust LQG-type controllers using the frequency domain loop transfer recovery (LTR) method is considered, and the method is applied to a large antenna model. Analytical results regarding the regions of stability for LQG-type controllers in the presence of actuator nonlinearities are also presented. The results obtained for the large antenna indicate that the LQG/LTR method is a promising approach for control system design for flexible spacecraft. For the second type of controllers (collocated controllers), it is proved that the stability is maintained in the presence of certain commonly encountered nonlinearities and first-order actuator dynamics. These results indicate that collocated controllers are good candidates for robust control in situations where model errors are large.

  5. Robustness analysis method for orbit control

    NASA Astrophysics Data System (ADS)

    Zhang, Jingrui; Yang, Keying; Qi, Rui; Zhao, Shuge; Li, Yanyan

    2017-08-01

    Satellite orbits require periodical maintenance due to the presence of perturbations. However, random errors caused by inaccurate orbit determination and thrust implementation may lead to failure of the orbit control strategy. Therefore, it is necessary to analyze the robustness of the orbit control methods. Feasible strategies which are tolerant to errors of a certain magnitude can be developed to perform reliable orbit control for the satellite. In this paper, first, the orbital dynamic model is formulated by Gauss' form of the planetary equation using the mean orbit elements; the atmospheric drag and the Earth's non-spherical perturbations are taken into consideration in this model. Second, an impulsive control strategy employing the differential correction algorithm is developed to maintain the satellite trajectory parameters in given ranges. Finally, the robustness of the impulsive control method is analyzed through Monte Carlo simulations while taking orbit determination error and thrust error into account.

  6. Real Time & Power Efficient Adaptive - Robust Control

    NASA Astrophysics Data System (ADS)

    Ioan Gliga, Lavinius; Constantin Mihai, Cosmin; Lupu, Ciprian; Popescu, Dumitru

    2017-01-01

    A design procedure for a control system suited for dynamic variable processes is presented in this paper. The proposed adaptive - robust control strategy considers both adaptive control advantages and robust control benefits. It estimates the degradation of the system’s performances due to the dynamic variation in the process and it then utilizes it to determine when the system must be adapted with a redesign of the robust controller. A single integral criterion is used for the identification of the process, and for the design of the control algorithm, which is expressed in direct form, through a cost function defined in the space of the parameters of both the process and the controller. For the minimization of this nonlinear function, an adequate mathematical programming minimization method is used. The theoretical approach presented in this paper was validated for a closed loop control system, simulated in an application developed in C. Because of the reduced number of operations, this method is suitable for implementation on fast processes. Due to its effectiveness, it increases the idle time of the CPU, thereby saving electrical energy.

  7. Robust Control of Uncertain Nonlinear Systems

    DTIC Science & Technology

    1992-01-01

    objective (Packard and Doyle, 1987). Progress has been made since on combining H2 and H., performance objectives, ( Doyle, Zhou, and Bodenheimer (1989)). New...and B. Bodenheimer , 1990 American Control Conference, San Diego, CA. 17. "Towards a methodology of robust parameter identification," It.S. Smith and

  8. Active robust control of wind turbines

    NASA Astrophysics Data System (ADS)

    Rezaei, Vahid

    The research work conducted in this thesis focuses on robustness of wind energy conversion system with respect to faults in pitch actuator in order to prevent unnecessary emergency shutdown, and keep the turbine operational without significant inefficiency in its overall performance. The objective is to investigate the feasibility of using a fault estimator and a light detection and ranging (LIDAR) system as additional sensors to design a suitable control system for wind turbines. Robust control technique is used to address these issues. Three controllers are proposed in this work that try to address sources of inaccuracy in wind turbine operation: An active fault tolerant controller is first designed using a fault estimator. It is shown that a set of locally robust controllers with respect to the fault, together with a suitable smooth mixing approach, manages to overcome the problem of faults in the pitch actuator. To address the wind-dependent behavior of turbines, a second controller is designed using the LIDAR sensor. In this configuration, LIDAR provides the look ahead wind information and generates a smooth scheduling signal to provide active robustness with respect to the changes in wind speed. Lastly, utilizing both the fault estimator and LIDAR, a 2-dimensional wind-dependent active fault tolerant controller is developed to control the wind turbine in region 3 of operation. The feasibility of the proposed ideas is verified in simulation. For this purpose, the US National Renewable Energy Laboratory's FAST code is used to model the 3-balded controls advanced research turbine. A discussion on practical considerations and ideas for future work are also presented.

  9. 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.

  10. 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.

  11. Robust Stabilization Control for an Electric Bicycle

    NASA Astrophysics Data System (ADS)

    Kawamura, Takuro; Murakami, Toshiyuki

    Recently, bicycles have gained immense popularity because they have high mobility and are an environment-friendly means of transport. However, many people tend to avoid riding a bicycle because it is unstable. In order to solve this problem, stabilization control for a bicycle has been researched. The aim of this study is improvement of the robustness in stabilization control. To achieve this goal, control systems that use a camber angle disturbance observer (CADO) are proposed. Two kinds of CADOs are proposed in this paper, and the performances of these two observers are compared. The proposed control systems provide higher robustness than does the conventional method. The validity of the proposed methods is confirmed by the experimental results.

  12. Robust adaptive control of HVDC systems

    SciTech Connect

    Reeve, J.; Sultan, M. )

    1994-07-01

    The transient performance of an HVDC power system is highly dependent on the parameters of the current/voltage regulators of the converter controls. In order to better accommodate changes in system structure or dc operating conditions, this paper introduces a new adaptive control strategy. The advantages of automatic tuning for continuous fine tuning are combined with predetermined gain scheduling in order to achieve robustness for large disturbances. Examples are provided for a digitally simulated back-to-back dc system.

  13. Robust dynamic inversion control laws for aircraft control

    NASA Technical Reports Server (NTRS)

    Balas, Gary J.; Garrard, William L.; Reiner, Jakob

    1992-01-01

    Dynamic inversion is a technique for control law design in which feedback is used to simultaneously cancel system dynamics and achieve desired dynamic response characteristics. However, dynamic inversion control laws lack robustness to modeling errors if improperly designed. This paper examines a simple linear example, control of roll rate about the body axis of high performance aircraft, to illustrate some robustness problems which may occur with a simple dynamic inversion control law. The paper demonstrates how structured singular value synthesis techniques can be used to enhance the robustness properties of the dynamic inversion controller.

  14. 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.

  15. 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.

  16. Robust control technique for nuclear power plants

    SciTech Connect

    Murphy, G.V.; Bailey, J.M.

    1989-03-01

    This report summarizes the linear quadratic Guassian (LQG) design technique with loop transfer recovery (LQG/LTR) for design of control systems. The concepts of return ratio, return difference, inverse return difference, and singular values are summarized. The LQG/LTR design technique allows the synthesis of a robust control system. To illustrate the LQG/LTR technique, a linearized model of a simple process has been chosen. The process has three state variables, one input, and one output. Three control system design methods are compared: LQG, LQG/LTR, and a proportional plus integral controller (PI). 7 refs., 20 figs., 6 tabs.

  17. Randomised controlled trial of mesalazine in IBS

    PubMed Central

    Barbara, Giovanni; Cremon, Cesare; Annese, Vito; Basilisco, Guido; Bazzoli, Franco; Bellini, Massimo; Benedetti, Antonio; Benini, Luigi; Bossa, Fabrizio; Buldrini, Paola; Cicala, Michele; Cuomo, Rosario; Germanà, Bastianello; Molteni, Paola; Neri, Matteo; Rodi, Marcello; Saggioro, Alfredo; Scribano, Maria Lia; Vecchi, Maurizio; Zoli, Giorgio; Corinaldesi, Roberto; Stanghellini, Vincenzo

    2016-01-01

    Objective Low-grade intestinal inflammation plays a role in the pathophysiology of IBS. In this trial, we aimed at evaluating the efficacy and safety of mesalazine in patients with IBS. Design We conducted a phase 3, multicentre, tertiary setting, randomised, double-blind, placebo-controlled trial in patients with Rome III confirmed IBS. Patients were randomly assigned to either mesalazine, 800 mg, or placebo, three times daily for 12 weeks, and were followed for additional 12 weeks. The primary efficacy endpoint was satisfactory relief of abdominal pain/discomfort for at least half of the weeks of the treatment period. The key secondary endpoint was satisfactory relief of overall IBS symptoms. Supportive analyses were also performed classifying as responders patients with a percentage of affirmative answers of at least 75% or >75% of time. Results A total of 185 patients with IBS were enrolled from 21 centres. For the primary endpoint, the responder patients were 68.6% in the mesalazine group versus 67.4% in the placebo group (p=0.870; 95% CI −12.8 to 15.1). In explorative analyses, with the 75% rule or >75% rule, the percentage of responders was greater in the mesalazine group with a difference over placebo of 11.6% (p=0.115; 95% CI −2.7% to 26.0%) and 5.9% (p=0.404; 95% CI −7.8% to 19.4%), respectively, although these differences were not significant. For the key secondary endpoint, overall symptoms improved in the mesalazine group and reached a significant difference of 15.1% versus placebo (p=0.032; 95% CI 1.5% to 28.7%) with the >75% rule. Conclusions Mesalazine treatment was not superior than placebo on the study primary endpoint. However, a subgroup of patients with IBS showed a sustained therapy response and benefits from a mesalazine therapy. Trial registration number ClincialTrials.gov number, NCT00626288. PMID:25533646

  18. Robustness

    NASA Technical Reports Server (NTRS)

    Ryan, R.

    1993-01-01

    Robustness is a buzz word common to all newly proposed space systems design as well as many new commercial products. The image that one conjures up when the word appears is a 'Paul Bunyon' (lumberjack design), strong and hearty; healthy with margins in all aspects of the design. In actuality, robustness is much broader in scope than margins, including such factors as simplicity, redundancy, desensitization to parameter variations, control of parameter variations (environments flucation), and operational approaches. These must be traded with concepts, materials, and fabrication approaches against the criteria of performance, cost, and reliability. This includes manufacturing, assembly, processing, checkout, and operations. The design engineer or project chief is faced with finding ways and means to inculcate robustness into an operational design. First, however, be sure he understands the definition and goals of robustness. This paper will deal with these issues as well as the need for the requirement for robustness.

  19. 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.

  20. Robust Control Design for Flight Control

    DTIC Science & Technology

    1989-07-01

    to achieve desired performance over the full flight envelope when linear feedback is employed. Exact linearization methods [48] provide means for...designing nonlinear feedback laws which satisfy these requirements. However, exact linearization is not always compatible with control authority...specific situations. The most promising approaches appear to be those associated with methods of exact linearization . This procedure is based on some

  1. Robust control of ionic polymer metal composites

    NASA Astrophysics Data System (ADS)

    Kang, Sunhyuk; Shin, Jongho; Kim, Seong Jun; Kim, H. Jin; Hyup Kim, Yong

    2007-12-01

    Ionic polymer-metal composites (IPMCs) have been considered for various applications due to their light weight, large bending, and low actuation voltage requirements. However, their response can be slow and vary widely, depending on various factors such as fabrication processes, water content, and contact conditions with the electrodes. In order to utilize their capability in various high-performance microelectromechanical systems, controllers need to address this uncertainty and non-repeatability while improving the response speed. In this work, we identified an empirical model for the dynamic relationship between the applied voltage and the IPMC beam deflection, which includes the uncertainties and variations of the response. Then, four types of controller were designed, and their performances were compared: a proportional-integral-derivative (PID) controller with optimized gains using a co-evolutionary algorithm, and three types of robust controller based on H_\\infty , H_\\infty with loop shaping, and μ-synthesis, respectively. Our results show that the robust control techniques can significantly improve the IPMC performance against non-repeatability or parametric uncertainties, in terms of the faster response and lower overshoot than the PID control, using lower actuation voltage.

  2. Robust model predictive control of Wiener systems

    NASA Astrophysics Data System (ADS)

    Biagiola, S. I.; Figueroa, J. L.

    2011-03-01

    Block-oriented models (BOMs) have shown to be appealing and efficient as nonlinear representations for many applications. They are at the same time valid and simple models in a more extensive region than time-invariant linear models. In this work, Wiener models are considered. They are one of the most diffused BOMs, and their structure consists in a linear dynamics in cascade with a nonlinear static block. Particularly, the problem of control of these systems in the presence of uncertainty is treated. The proposed methodology makes use of a robust identification procedure in order to obtain a robust model to represent the uncertain system. This model is then employed to design a model predictive controller. The mathematical problem involved in the controller design is formulated in the context of the existing linear matrix inequalities (LMI) theory. The main feature of this approach is that it takes advantage of the static nature of the nonlinearity, which allows to solve the control problem by focusing only in the linear dynamics. This formulation results in a simplified design procedure, because the original nonlinear model predictive control (MPC) problem turns into a linear one.

  3. 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…

  4. 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…

  5. 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.

  6. Adaptive control: Stability, convergence, and robustness

    NASA Technical Reports Server (NTRS)

    Sastry, Shankar; Bodson, Marc

    1989-01-01

    The deterministic theory of adaptive control (AC) is presented in an introduction for graduate students and practicing engineers. Chapters are devoted to basic AC approaches, notation and fundamental theorems, the identification problem, model-reference AC, parameter convergence using averaging techniques, and AC robustness. Consideration is given to the use of prior information, the global stability of indirect AC schemes, multivariable AC, linearizing AC for a class of nonlinear systems, AC of linearizable minimum-phase systems, and MIMO systems decouplable by static state feedback.

  7. System identification for robust control design

    SciTech Connect

    Dohner, J.L.

    1995-04-01

    System identification for the purpose of robust control design involves estimating a nominal model of a physical system and the uncertainty bounds of that nominal model via the use of experimentally measured input/output data. Although many algorithms have been developed to identify nominal models, little effort has been directed towards identifying uncertainty bounds. Therefore, in this document, a discussion of both nominal model identification and bounded output multiplicative uncertainty identification will be presented. This document is divided into several sections. Background information relevant to system identification and control design will be presented. A derivation of eigensystem realization type algorithms will be presented. An algorithm will be developed for calculating the maximum singular value of output multiplicative uncertainty from measured data. An application will be given involving the identification of a complex system with aliased dynamics, feedback control, and exogenous noise disturbances. And, finally, a short discussion of results will be presented.

  8. Robust, Practical Adaptive Control for Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Orr, Jeb. S.; VanZwieten, Tannen S.

    2012-01-01

    A modern mechanization of a classical adaptive control concept is presented with an application to launch vehicle attitude control systems. Due to a rigorous flight certification environment, many adaptive control concepts are infeasible when applied to high-risk aerospace systems; methods of stability analysis are either intractable for high complexity models or cannot be reconciled in light of classical requirements. Furthermore, many adaptive techniques appearing in the literature are not suitable for application to conditionally stable systems with complex flexible-body dynamics, as is often the case with launch vehicles. The present technique is a multiplicative forward loop gain adaptive law similar to that used for the NASA X-15 flight research vehicle. In digital implementation with several novel features, it is well-suited to application on aerodynamically unstable launch vehicles with thrust vector control via augmentation of the baseline attitude/attitude-rate feedback control scheme. The approach is compatible with standard design features of autopilots for launch vehicles, including phase stabilization of lateral bending and slosh via linear filters. In addition, the method of assessing flight control stability via classical gain and phase margins is not affected under reasonable assumptions. The algorithm s ability to recover from certain unstable operating regimes can in fact be understood in terms of frequency-domain criteria. Finally, simulation results are presented that confirm the ability of the algorithm to improve performance and robustness in realistic failure scenarios.

  9. Application of stochastic robustness to aircraft control systems

    NASA Technical Reports Server (NTRS)

    Ryan, Laura E.

    1990-01-01

    Guaranteeing robustness has long been an important design objective of control system analysis. Stochastic robustness is a simple numerical procedure that can be used to measure and gain insight into robustness properties associated with linear control systems. In the realm of aircraft control systems, problems such as the effects of flight condition perturbations and model-order uncertainties on robustness are easily and effectively analyzed using stochastic robustness. The concept of stochastic robustness is reviewed and examples are presented demonstrating its use in flight control system analysis.

  10. Sources of Bias in Outcome Assessment in Randomised Controlled Trials: A Case Study

    ERIC Educational Resources Information Center

    Ainsworth, Hannah; Hewitt, Catherine E.; Higgins, Steve; Wiggins, Andy; Torgerson, David J.; Torgerson, Carole J.

    2015-01-01

    Randomised controlled trials (RCTs) can be at risk of bias. Using data from a RCT, we considered the impact of post-randomisation bias. We compared the trial primary outcome, which was administered blindly, with the secondary outcome, which was not administered blindly. From 44 schools, 522 children were randomised to receive a one-to-one maths…

  11. Robust Planning and Control Using Intelligent Products

    NASA Astrophysics Data System (ADS)

    Meyer, Gerben G.; Wortmann, J. C. (Hans)

    The advances in production planning and control in the last decades have confirmed the centralized nature of the planning function. However, centralization has disadvantages when quick response to local production problems is required. Therefore, renewed interest in decentralized approaches emerges. This paper investigates the possibility to use intelligent products for decentralized handling of disturbances. Intelligent products are aware of their local context and they can negotiate with local manufacturing resources. Therefore, local solutions for problems can be suggested, virtually at the same time at which the problem occurs. The paper demonstrates the viability of this approach via a simulation study. For reasons of comparison, the TAC SCM environment is used. Moreover, robustness is taken as an additional measurement of performance. The results of the simulations are encouraging.

  12. 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

  13. 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

  14. Robust steering control of spacecraft carrier rockets

    NASA Astrophysics Data System (ADS)

    Correa, Adriana Elysa Alimandro; da Rosa, Alex; Ferreira, Henrique Cezar; Ishihara, Joao Yoshiyuki; Borges, Renato Alves; Sheptun, Yuri Dmitrievich

    In the year of 2003 it was established a cooperation agreement between Ukraine and Brazil for utilization of Cyclone-4 launch vehicle at Alcantara Launch Center. The company responsible for the marketing and operation of launch services is the company bi-national Alcantara Cyclone Space (ACS). The Cyclone-4 launch vehicle is the newest version of the Ukrainian Cyclone family launchers developed by Yuzhnoye State Design Office. This family has been used for many successful spacecrafts launches since 1969. This paper is concerned with the yaw stabilization problem around a nominal trajectory for the third stage of a satellite carrier rocket similar to the Cyclone-4. Only the steering machine of the main engine is considered as actuator. The dynamic behavior of the third stage around the nominal trajectory is modeled as a fourthorder time-varying linear system whereas the steering machine is modeled as a linear dynamical system up to third order. The values of the parameters of the steering machine model are unknown, however belonging to known intervals. As the main result, the stabilization problem is solved with a proportional derivative (PD) controller. The proposed tuning approach takes into account the robustness of the controller with respect to the steering machine model uncertainties. The performance of the PD controller is demonstrated by simulation results.

  15. Robust control for snake maneuver design of missile

    NASA Astrophysics Data System (ADS)

    Kun, Ya; Chen, Xin; Li, Chuntao

    2017-01-01

    For the performance of missile with high Mach number and strongly nonlinear dynamics, this paper uses robust control to design maneuver controller. Robust servomechanism linear quadratic regulator (RSLQR) control is used to form the inner loop and proportional-plus-integral (PI) control is used to provide yawing tracking with no error. Contrast simulations under three types of deviation have been done to confirm robustness of the RSLQR-plus-PI control. Simulation results shows that RSLQR-plus-PI control would resist the disturbance and maintain the properties of the controller, guarantee the robustness and stability of missile more effectively than pure PI control.

  16. Computer-aided-analysis of linear control system robustness

    NASA Technical Reports Server (NTRS)

    Stengel, Robert F.; Ray, Laura R.

    1990-01-01

    Stochastic robustness is a simple technique used to estimate the stability and performance robustness of linear, time-invariant systems. The use of high-speed graphics workstations and control system design software in stochastic robustness analysis is discussed and demonstrated. It is shown that stochastic robustness makes good use of modern computational and graphic tools, and it is easily implemented using commercial control system design and analysis software.

  17. Combined Integral and Robust Control of the Segmented Mirror Telescope

    DTIC Science & Technology

    2009-12-01

    60 Hz, Best Perf ............ 41 Figure 29. Zernike Control Model ........................................................................ 42 Figure...builds on previous robust control design by combining classical control with an H robust controller on a Singular Value Decomposition reduced model ...It also presents reduction using Zernike polynomials and applies it to the integral control model as an alternate to Singular Value Decomposition

  18. Application of stochastic robustness to aircraft control systems

    NASA Technical Reports Server (NTRS)

    Stengel, Robert F.; Ryan, Laura E.

    1989-01-01

    Stochastic robustness, a simple numerical procedure for estimating the stability robustness of linear, time-invariant systems, is applied to a forward-swept-wing aircraft control system. Based on Monte Carlo evaluation of the system's closed-loop eignevalues, this analysis approach introduces the probability of instability as a scalar stability robustness measure. The related stochastic root locus provides insight into robustness characteristics of the closed-loop system. Three Linear Quadratic controllers of decreasing robustness are chosen to demonstrate the use of stochastic robustness to analyze and compare control designs. Examples are presented illustrating the use of stochastic robustness analysis to address the effects of actuator dynamics and unmodeled dynamics on the stability robustness of the forward-swept-wing aircraft.

  19. Robust adaptive control for Unmanned Aerial Vehicles

    NASA Astrophysics Data System (ADS)

    Kahveci, Nazli E.

    anti-windup compensation. Our analysis on the indirect adaptive scheme reveals that the perturbation terms due to parameter errors do not cause any unbounded signals in the closed-loop. The stability of the adaptive system is established, and the properties of the proposed control scheme are demonstrated through simulations on a UAV model with input magnitude saturation constraints. The robust adaptive control design is further developed to extend our results to rate-saturated systems.

  20. [Psychotherapy in bipolar disorders -- randomised controlled trials of treatment efficacy].

    PubMed

    Rode, Sibylle; Wagner, Petra; Bräunig, Peter

    2006-03-01

    On the basis of a vulnerability-stress-model psycho-educative, cognitive-behavioural, family-oriented and interpersonal approaches of psychotherapy for bipolar disorders are described. This is followed by a review of randomised controlled trials investigating the treatment efficacy of psychotherapeutic interventions. These studies show positive results particularly for psychoeducation, cognitive-behavioural therapy and family-oriented therapy. Finally, it is discussed in which respects evidence for the successful implementation of psychotherapy is still missing and why it is so important to move towards manualized psychotherapeutic programs.

  1. 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.

  2. Integrated identification and robust control tuning for large space structures

    NASA Technical Reports Server (NTRS)

    Yam, Y.; Bayard, D. S.; Scheid, R. E.

    1990-01-01

    System identification is studied for the explicit purpose of supporting modern H-infinity robust control design objectives. In the analysis, the true plant is not assumed to be in the identification model set. An integrated identification/robust control problem is posed in which the optimal solution guarantees the best robust performance relative to the system information contained in a given experimental data set. A numerical example demonstrating an approximate solution to the problem indicates the usefulness of the approach.

  3. Integrated identification and robust control tuning for large space structures

    NASA Technical Reports Server (NTRS)

    Yam, Y.; Bayard, D. S.; Scheid, R. E.

    1990-01-01

    System identification is studied for the explicit purpose of supporting modern H-infinity robust control design objectives. In the analysis, the true plant is not assumed to be in the identification model set. An integrated identification/robust control problem is posed in which the optimal solution guarantees the best robust performance relative to the system information contained in a given experimental data set. A numerical example demonstrating an approximate solution to the problem indicates the usefulness of the approach.

  4. A Randomised Controlled Trial of complete denture impression materials

    PubMed Central

    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.

    2014-01-01

    Objectives 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. Methods 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. Results 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). Conclusion There is significant evidence that dentures made from silicone impressions were preferred by patients. Clinical significance 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. Trial Registration: 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. PMID:24995473

  5. 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.

  6. A criterion for joint optimization of identification and robust control

    NASA Technical Reports Server (NTRS)

    Bayard, D. S.; Yam, Y.; Mettler, E.

    1992-01-01

    A criterion for system identification is developed that is consistent with the intended used of the fitted model for modern robust control synthesis. Specifically, a joint optimization problem is posed which simultaneously solves the plant model estimate and control design, so as to optimize robust performance over the set of plants consistent with a specified experimental data set.

  7. 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.

  8. Stochastic robustness of linear control systems

    NASA Technical Reports Server (NTRS)

    Stengel, Robert F.; Ryan, Laura E.

    1990-01-01

    A simple numerical procedure for estimating the stochastic robustness of a linear, time-invariant system is described. Monte Carlo evaluation of the system's eigenvalues allows the probability of instability and the related stochastic root locus to be estimated. This definition of robustness is an alternative to existing deterministic definitions that address both structured and unstructured parameter variations directly. This analysis approach treats not only Gaussian parameter uncertainties but non-Gaussian cases, including uncertain-but-bounded variations. Trivial extensions of the procedure admit alternate discriminants to be considered. Thus, the probabilities that stipulated degrees of instability will be exceeded or that closed-loop roots will leave desirable regions also can be estimated. Results are particularly amenable to graphical presentation.

  9. Robustness Analysis and Optimally Robust Control Design via Sum-of-Squares

    NASA Technical Reports Server (NTRS)

    Dorobantu, Andrei; Crespo, Luis G.; Seiler, Peter J.

    2012-01-01

    A control analysis and design framework is proposed for systems subject to parametric uncertainty. The underlying strategies are based on sum-of-squares (SOS) polynomial analysis and nonlinear optimization to design an optimally robust controller. The approach determines a maximum uncertainty range for which the closed-loop system satisfies a set of stability and performance requirements. These requirements, de ned as inequality constraints on several metrics, are restricted to polynomial functions of the uncertainty. To quantify robustness, SOS analysis is used to prove that the closed-loop system complies with the requirements for a given uncertainty range. The maximum uncertainty range, calculated by assessing a sequence of increasingly larger ranges, serves as a robustness metric for the closed-loop system. To optimize the control design, nonlinear optimization is used to enlarge the maximum uncertainty range by tuning the controller gains. Hence, the resulting controller is optimally robust to parametric uncertainty. This approach balances the robustness margins corresponding to each requirement in order to maximize the aggregate system robustness. The proposed framework is applied to a simple linear short-period aircraft model with uncertain aerodynamic coefficients.

  10. Improving venous ulcer healing: designing and reporting randomised controlled trials.

    PubMed

    Weller, Carolina D; McNeil, John; Evans, Sue; Reid, Christopher

    2010-02-01

    The randomised controlled trial (RCT) is often considered the gold standard for judging the benefits of treatments. The application of randomised controlled clinical trials to treatments of venous ulcer healing has lagged behind that of other areas of medicine. To interpret the results of an RCT, readers must understand a variety of aspects of their design, analysis and interpretation. Venous ulcer disease has a high prevalence and has a significant socioeconomic impact in most parts of the world. The management of venous ulcers causes a considerable strain on the health system and is likely to worsen in future. The multi-layer high compression system is described as the current gold standard for treating venous ulcers. A recent meta-analysis of bandaging systems found that multi-layer compression bandages appeared to be superior to single-layer bandages in promoting venous ulcer healing. However, it was noted that many of the studies had small sample sizes and the quality of research in the area was poor. The consolidating standards of reporting trials (CONSORT) statement can help clinicians to discern high-quality studies from ones of poorer quality. This paper discusses how CONSORT can help clinicians and researchers to design and report quality studies to contribute to evidence-based venous ulcer healing.

  11. Democratic therapeutic community treatment for personality disorder: randomised controlled trial.

    PubMed

    Pearce, Steve; Scott, Lisle; Attwood, Gillian; Saunders, Kate; Dean, Madeleine; De Ridder, Ritz; Galea, David; Konstantinidou, Haroula; Crawford, Mike

    2017-02-01

    Democratic therapeutic community (DTC) treatment has been used for many years in an effort to help people with personality disorder. High-quality evidence from randomised controlled trials (RCTs) is absent. To test whether DTC treatment reduces use of in-patient services and improves the mental health of people with personality disorder. An RCT of 70 people meeting DSM-IV criteria for personality disorder (trial registration: ISRCTN57363317). The intervention was DTC and the control condition was crisis planning plus treatment as usual (TAU). The primary outcome was days of in-patient psychiatric treatment. Secondary outcomes were social function, mental health status, self-harm and aggression, attendance at emergency departments and primary care, and satisfaction with care. All outcomes were measured at 12 and 24 months after randomisation. Number of in-patient days at follow-up was low among all participants and there was no difference between groups. At 24 months, self- and other directed aggression and satisfaction with care were significantly improved in the DTC compared with the TAU group. DTC is more effective than TAU in improving outcomes in personality disorder. Further studies are required to confirm this conclusion. © The Royal College of Psychiatrists 2017.

  12. 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

  13. Cognitive analytic therapy for personality disorder: randomised controlled trial.

    PubMed

    Clarke, Susan; Thomas, Peter; James, Kirsty

    2013-02-01

    Cognitive analytic therapy (CAT) is a theoretically coherent approach developed to address common processes underlying personality disorders, but is supported by limited empirical evidence. To investigate the effectiveness of time-limited CAT for participants with personality disorder. A service-based randomised controlled trial (trial registration: ISRCTN79596618) comparing 24 sessions of CAT (n = 38) and treatment as usual (TAU) (n = 40) over 10 months for individuals with personality disorder. Primary outcomes were measures of psychological symptoms and interpersonal difficulties. Participants receiving CAT showed reduced symptoms and experienced substantial benefits compared with TAU controls, who showed signs of deterioration during the treatment period. Cognitive analytic therapy is more effective than TAU in improving outcomes associated with personality disorder. More elaborate and controlled evaluations of CAT are needed in the future.

  14. Cost averaging techniques for robust control of flexible structural systems

    NASA Technical Reports Server (NTRS)

    Hagood, Nesbitt W.; Crawley, Edward F.

    1991-01-01

    Viewgraphs on cost averaging techniques for robust control of flexible structural systems are presented. Topics covered include: modeling of parameterized systems; average cost analysis; reduction of parameterized systems; and static and dynamic controller synthesis.

  15. Robust attitude tracking control of small-scale unmanned helicopter

    NASA Astrophysics Data System (ADS)

    Wang, Xiafu; Chen, You; Lu, Geng; Zhong, Yisheng

    2015-06-01

    Robust attitude control problem for small-scale unmanned helicopters is investigated to improve attitude control performances of roll and pitch channels under both small and large amplitude manoeuvre flight conditions. The model of the roll or pitch angular dynamics is regarded as a nominal single-input single-output linear system with equivalent disturbances which contain nonlinear uncertainties, coupling-effects, parameter perturbations, and external disturbances. Based on the signal compensation method, a robust controller is designed with two parts: a proportional-derivative controller and a robust compensator. The designed controller is linear and time-invariant, so it can be easily realised. The robust properties of the closed-loop system are proven. According to the ADS-33E-PRF military rotorcraft standard, the controller can achieve top control performances. Experimental results demonstrate the effectiveness of the proposed control strategy.

  16. Robust transition control of a Martian coaxial tiltrotor aerobot

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Underwood, Craig

    2014-06-01

    Hyperion is an autonomous solar-electric powered coaxial tiltrotor aerobot proposed to investigate the Isidis Planitia region on Mars. The objective of this paper is to propose a robust control strategy for transition flight between hover and cruise based on the supervisory control method and the linear robust control method. The proposed transition controller has two levels. The lower level is a series of candidate controllers for the subproblems, which are obtained by the operation of divide and conquer. The higher level uses the state variables to determine which lower level candidate controller should be used. The candidate controllers are solved using the μ synthesis and the conventional longitudinal and lateral control loops. The robustness of the candidate controllers is guaranteed by the robust control theory. The stability and robustness of the transition controller is determined by the switch logic in the higher level. The stability of the proposed control strategy is analyzed. A 6 Degree of Freedom simulation with uncertain aerodynamic model is used to show the robustness and the performance of the proposed controller.

  17. Structured Robust Loop shaping control for HIMAT System Using PSO

    NASA Astrophysics Data System (ADS)

    Kaitwanidvilai, Somyot; Jangwanitlert, Anuwat; Parnichkun, Manukid

    2009-01-01

    Robust loop shaping control is a feasible method for designing a robust controller; however, the controller designed by this method is complicated and difficult to implement practically. To overcome this problem, in this paper, a new design technique of a fixed-structure robust loop shaping controller for a highly maneuverable airplane, HIMAT, is proposed. The performance and robust stability conditions of the designed system satisfying H∞ loop shaping control are formulated as the objective function in the optimization problem. Particle Swarm Optimization (PSO) technique is adopted to solve this problem and to achieve the control parameters of the proposed controller. Simulation results demonstrate that the proposed approach is numerically efficient and leads to performance comparable to that of the other method.

  18. Robust and optimal attitude control of spacecraft with disturbances

    NASA Astrophysics Data System (ADS)

    Park, Yonmook

    2015-05-01

    In this paper, a robust and optimal attitude control design that uses the Euler angles and angular velocities feedback is presented for regulation of spacecraft with disturbances. In the control design, it is assumed that the disturbance signal has the information of the system state. In addition, it is assumed that the disturbance signal tries to maximise the same performance index that the control input tries to minimise. After proposing a robust attitude control law that can stabilise the complete attitude motion of spacecraft with disturbances, the optimal attitude control problem of spacecraft is formulated as the optimal game-theoretic problem. Then it is shown that the proposed robust attitude control law is the optimal solution of the optimal game-theoretic problem. The stability of the closed-loop system for the proposed robust and optimal control law is proven by the LaSalle invariance principle. The theoretical results presented in this paper are illustrated by a numerical example.

  19. 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

  20. A pragmatic, multicentre, randomised controlled trial comparing stapled haemorrhoidopexy to traditional excisional surgery for haemorrhoidal disease (eTHoS): study protocol for a randomised controlled trial.

    PubMed

    Watson, Angus J M; Bruhn, Hanne; MacLeod, Kathleen; McDonald, Alison; McPherson, Gladys; Kilonzo, Mary; Norrie, John; Loudon, Malcolm A; McCormack, Kirsty; Buckley, Brian; Brown, Steven; Curran, Finlay; Jayne, David; Rajagopal, Ramesh; Cook, Jonathan A

    2014-11-11

    Current interventions for haemorrhoidal disease include traditional haemorrhoidectomy (TH) and stapled haemorrhoidopexy (SH) surgery. However, uncertainty remains as to how they compare from a clinical, quality of life (QoL) and economic perspective. The study is therefore designed to determine whether SH is more effective and more cost-effective, compared with TH. eTHoS (either Traditional Haemorrhoidectomy or Stapled Haemorrhoidopexy for Haemorrhoidal Disease) is a pragmatic, multicentre, randomised controlled trial. Currently, 29 secondary care centres are open to recruitment. Patients, aged 18 year or older, with circumferential haemorrhoids grade II to IV, are eligible to take part. The primary clinical and economic outcomes are QoL profile (area under the curve derived from the EuroQol Group's 5 Dimension Health Status Questionnaire (EQ-5D) at all assessment points) and incremental cost per quality adjusted life year (QALY) based on the responses to the EQ-5D at 24 months. The secondary outcomes include a comparison of the SF-36 scores, pain and symptoms sub-domains, disease recurrence, complication rates and direct and indirect costs to the National Health Service (NHS). A sample size of n =338 per group has been calculated to provide 90% power to detect a difference in the mean area under the curve (AUC) of 0.25 standard deviations derived from EQ-5D score measurements, with a two-sided significance level of 5%. Allowing for non-response, 400 participants will be randomised per group. Randomisation will utilise a minimisation algorithm that incorporates centre, grade of haemorrhoidal disease, baseline EQ-5D score and gender. Blinding of participants and outcome assessors is not attempted. This is one of the largest trials of its kind. In the United Kingdom alone, 29,000 operations for haemorrhoidal disease are done annually. The trial is therefore designed to give robust evidence on which clinicians and health service managers can base management decisions

  1. 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.

  2. Effect of handwashing on child health: a randomised controlled trial.

    PubMed

    Luby, Stephen P; Agboatwalla, Mubina; Feikin, Daniel R; Painter, John; Billhimer, Ward; Altaf, Arshad; Hoekstra, Robert M

    More than 3.5 million children aged less than 5 years die from diarrhoea and acute lower respiratory-tract infection every year. We undertook a randomised controlled trial to assess the effect of handwashing promotion with soap on the incidence of acute respiratory infection, impetigo, and diarrhoea. In adjoining squatter settlements in Karachi, Pakistan, we randomly assigned 25 neighbourhoods to handwashing promotion; 11 neighbourhoods (306 households) were randomised as controls. In neighbourhoods with handwashing promotion, 300 households each were assigned to antibacterial soap containing 1.2% triclocarban and to plain soap. Fieldworkers visited households weekly for 1 year to encourage handwashing by residents in soap households and to record symptoms in all households. Primary study outcomes were diarrhoea, impetigo, and acute respiratory-tract infections (ie, the number of new episodes of illness per person-weeks at risk). Pneumonia was defined according to the WHO clinical case definition. Analysis was by intention to treat. Children younger than 5 years in households that received plain soap and handwashing promotion had a 50% lower incidence of pneumonia than controls (95% CI (-65% to -34%). Also compared with controls, children younger than 15 years in households with plain soap had a 53% lower incidence of diarrhoea (-65% to -41%) and a 34% lower incidence of impetigo (-52% to -16%). Incidence of disease did not differ significantly between households given plain soap compared with those given antibacterial soap. Handwashing with soap prevents the two clinical syndromes that cause the largest number of childhood deaths globally-namely, diarrhoea and acute lower respiratory infections. Handwashing with daily bathing also prevents impetigo.

  3. 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.

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

    PubMed

    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

    2014-03-01

    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. 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. 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). PFS can be regarded as a robust surrogate for overall survival in dacarbazine-controlled randomised trials of metastatic melanoma; we postulate that this

  5. Pupil Control Behavior, Student Brinkmanship and Environmental Robustness.

    ERIC Educational Resources Information Center

    Brown, Ralph E.; Licata, Joseph W.

    1978-01-01

    From the perspective of the student audience, the general results of the study suggest that, as teacher custodialism increases, the more robust are acts of student brinksmanship, the less robust is the teacher's pupil control behavior, and the less the teacher is liked by students. (Author)

  6. 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.

  7. Robust control design verification using the modular modeling system

    SciTech Connect

    Edwards, R.M.; Ben-Abdennour, A.; Lee, K.Y.

    1991-01-01

    The Modular Modeling System (B W MMS) is being used as a design tool to verify robust controller designs for improving power plant performance while also providing fault-accommodating capabilities. These controllers are designed based on optimal control theory and are thus model based controllers which are targeted for implementation in a computer based digital control environment. The MMS is being successfully used to verify that the controllers are tolerant of uncertainties between the plant model employed in the controller and the actual plant; i.e., that they are robust. The two areas in which the MMS is being used for this purpose is in the design of (1) a reactor power controller with improved reactor temperature response, and (2) the design of a multiple input multiple output (MIMO) robust fault-accommodating controller for a deaerator level and pressure control problem.

  8. Robust tuning of robot control systems

    NASA Technical Reports Server (NTRS)

    Minis, I.; Uebel, M.

    1992-01-01

    The computed torque control problem is examined for a robot arm with flexible, geared, joint drive systems which are typical in many industrial robots. The standard computed torque algorithm is not directly applicable to this class of manipulators because of the dynamics introduced by the joint drive system. The proposed approach to computed torque control combines a computed torque algorithm with torque controller at each joint. Three such control schemes are proposed. The first scheme uses the joint torque control system currently implemented on the robot arm and a novel form of the computed torque algorithm. The other two use the standard computed torque algorithm and a novel model following torque control system based on model following techniques. Standard tasks and performance indices are used to evaluate the performance of the controllers. Both numerical simulations and experiments are used in evaluation. The study shows that all three proposed systems lead to improved tracking performance over a conventional PD controller.

  9. 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.

  10. Probability-based stability robustness assessment of controlled structures

    SciTech Connect

    Field, R.V. Jr.; Voulgaris, P.G.; Bergman, L.A.

    1996-01-01

    Model uncertainty, if ignored, can seriously degrade the performance of an otherwise well-designed control system. If the level of this uncertainty is extreme, the system may even be driven to instability. In the context of structural control, performance degradation and instability imply excessive vibration or even structural failure. Robust control has typically been applied to the issue of model uncertainty through worst-case analyses. These traditional methods include the use of the structured singular value, as applied to the small gain condition, to provide estimates of controller robustness. However, this emphasis on the worst-case scenario has not allowed a probabilistic understanding of robust control. In this paper an attempt to view controller robustness as a probability measure is presented. The probability of failure due to parametric uncertainty is estimated using first-order reliability methods (FORM). It is demonstrated that this method can provide quite accurate results on the probability of failure of actively controlled structures. Moreover, a comparison of this method to a suitability modified structured singular value robustness analysis in a probabilistic framework is performed. It is shown that FORM is the superior analysis technique when applied to a controlled three degree-of-freedom structure. In addition, the robustness qualities of various active control design schemes such as LQR, H{sub 2}, H {sub oo}, and {mu}-synthesis is discussed in order to provide some design guidelines.

  11. Robust Nonlinear Control of Tailless Fighter Aircraft

    DTIC Science & Technology

    1999-02-01

    adaptive backstepping and nonlinear PI control , it is not very straightforward to establish this uniform asymptotic stability (in a set of error coordinates...tracking error coordinates for mechanical systems and ships controlled via adaptive back- stepping and nonlinear PI control algorithms. These results were

  12. A Robustly Stabilizing Model Predictive Control Algorithm

    NASA Technical Reports Server (NTRS)

    Ackmece, A. Behcet; Carson, John M., III

    2007-01-01

    A model predictive control (MPC) algorithm that differs from prior MPC algorithms has been developed for controlling an uncertain nonlinear system. This algorithm guarantees the resolvability of an associated finite-horizon optimal-control problem in a receding-horizon implementation.

  13. 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.

  14. High-performance quantitative robust switching control for optical telescopes

    NASA Astrophysics Data System (ADS)

    Lounsbury, William P.; Garcia-Sanz, Mario

    2014-07-01

    This paper introduces an innovative robust and nonlinear control design methodology for high-performance servosystems in optical telescopes. The dynamics of optical telescopes typically vary according to azimuth and altitude angles, temperature, friction, speed and acceleration, leading to nonlinearities and plant parameter uncertainty. The methodology proposed in this paper combines robust Quantitative Feedback Theory (QFT) techniques with nonlinear switching strategies that achieve simultaneously the best characteristics of a set of very active (fast) robust QFT controllers and very stable (slow) robust QFT controllers. A general dynamic model and a variety of specifications from several different commercially available amateur Newtonian telescopes are used for the controller design as well as the simulation and validation. It is also proven that the nonlinear/switching controller is stable for any switching strategy and switching velocity, according to described frequency conditions based on common quadratic Lyapunov functions (CQLF) and the circle criterion.

  15. Robust and reconfigurable flight control system design

    NASA Astrophysics Data System (ADS)

    Siwakosit, Wichai

    2001-07-01

    A reconfigurable flight control system is a control system which can automatically adapt itself to maintain the performance of a damaged aircraft to be as close as possible to that of the normal or undamaged one. This research focuses mainly on Multi-Input, Multi-Output (MIMO) reconfigurable flight control for an aircraft with damaged actuator(s) which may greatly affect the performance and control of the aircraft, and also pose a challenging flight control problem. The foundation of the control system is a baseline controller and an adaptive module which constitutes a reconfigurable part. The baseline controller ensures that the aircraft has acceptable performance and handling qualities throughout the flight envelope. The combination of a Quantitative Feedback Theory (QFT) Pre-Design Technique (PDT) and a Reduced-order, Linear, Dynamic Inversion (RLDI) control strategy yields a flight control system with good tracking performance and handling qualities with no Pilot Induced Oscillation (PIO) tendencies throughout the designated set of flight conditions. In addition, the system is highly immune to large uncertainties in the aircraft dynamics. The modified filtered-ɛ adaptive algorithm is developed and utilized in the adaptive module of the system. This adaptive algorithm performs well with MIMO system with the added advantage of not having to pre-identify the dynamics of the damaged aircraft, provided that the conditions of reconfigurability are met. An example of the proposed control system with the NASA F-18 HARV vehicle model and a damaged actuator demonstrates the effectiveness of the concept.

  16. 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

  17. 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.

  18. Vegetarian diet in mild hypertension: a randomised controlled trial.

    PubMed Central

    Margetts, B M; Beilin, L J; Vandongen, R; Armstrong, B K

    1986-01-01

    In a randomised crossover trial 58 subjects aged 30-64 with mild untreated hypertension were allocated either to a control group eating a typical omnivorous diet or to one of two groups eating an ovolactovegetarian diet for one of two six week periods. A fall in systolic blood pressure of the order of 5 mm Hg occurred during the vegetarian diet periods, with a corresponding rise on resuming a meat diet. The main nutrient changes with the vegetarian diet included an increase in the ratio of polyunsaturated to saturated fats and intake of fibre, calcium, and magnesium and a decrease in the intake of protein and vitamin B12. There were no consistent changes in urinary sodium or potassium excretion or body weight. In untreated subjects with mild hypertension, changing to a vegetarian diet may bring about a worthwhile fall in systolic blood pressure. PMID:3026552

  19. Robust Tracking Control for a Piezoelectric Actuator

    DTIC Science & Technology

    2006-01-01

    Actuators,” IEEE/ASME Trans. on Mechatronics , Vol. 5, No. 4, pp. 331-341, (2000) [2] H. Ahn, “Design of a Repetitive Control System for a...Hybrid Positioning Control with Large Stroke, High Loading and Sub-Micrometer Accu- racy,” Proc. IEEE International Conference on Mechatronics , Taipei...Furutani, M. Urushibata, and N. Mohri, “Displace- ment Control of Piezoelectric Element by Feedback of Induced Charge,” Journal of Nanotechnology , pp

  20. Robust multivariable turbofan engine control: A case study

    SciTech Connect

    Nordgren, R.E.; Nwokah, O.D.I.; Gastineau, Z.; Adibhatla, S.; Grewal, G.S.

    1994-12-31

    The application of robust controller design techniques to aircraft turbofan engine control problems has a long and intensive history. These applications have revealed many of the strengths and weaknesses of the many solution techniques. Quantitative Nyquist Array, are applied to the GE16 aircraft turbofan engine control problem for the purpose of designing a full flight envelope controller capable of meeting robust performance specifications. Performance and implementation issues of the two controllers are explored and compared to a control law based upon gain scheduling.

  1. Robust Adaptive Control of Multivariable Nonlinear Systems

    DTIC Science & Technology

    2008-11-01

    of time-delay margins for unmanned unstable tailless aircraft and aerial refueling autopilot design3, development of vision-based guidance laws...An Adaptive Approach to Nonaffine Control Design for Aircraft Applications, AIAA Journal of Guidance, Control and Dynamics, vol. 18, No. 6, pp. 1770

  2. Robust Adaptive Control of Multivariable Nonlinear Systems

    DTIC Science & Technology

    2011-03-28

    Systems: Challenge Problem Integration and NASA s Integrated Resilient Aircraft Control . We also revealed some similarities with the disturbance ... observer (DOB) controllers and identified the main features in the difference between them. The key feature of this difference is that the estimation loop

  3. Practical Methods for Robust Multivariable Control

    DTIC Science & Technology

    1991-12-31

    objectives in the face of both structured and unstructured uncertainty. Advances in the past two years have included relative-error methods for system ... identification , model reduction and control, better algorithms for H- and H2 control computations and new results on the analysis of stability

  4. Robust control of photoassociation of slow O + H collision

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Dong, Daoyi; Petersen, Ian R.; Rabitz, Herschel A.

    2017-02-01

    We show that robust laser pulses can be obtained by a sampling-based method to achieve a desired photoassociation probability when uncertainties in potential curves and laser amplitudes are considered. Optimal control simulations are performed using a time-dependent wave packet method based on a single electronic state. We use a small number of samples to construct a robust field and test the performance of this field using additional samples. Excellent outcomes are obtained based on the proposed method for different uncertainties. The robust control field achieves higher average photoassociation probabilities over the tested samples, in comparison with the probabilities achieved by the optimal field designed without using the sampling-based method. The sampling-based method may also be promising in the robust control of other molecular control goals.

  5. Computation of robustly stabilizing PID controllers for interval systems.

    PubMed

    Matušů, Radek; Prokop, Roman

    2016-01-01

    The paper is focused on the computation of all possible robustly stabilizing Proportional-Integral-Derivative (PID) controllers for plants with interval uncertainty. The main idea of the proposed method is based on Tan's (et al.) technique for calculation of (nominally) stabilizing PI and PID controllers or robustly stabilizing PI controllers by means of plotting the stability boundary locus in either P-I plane or P-I-D space. Refinement of the existing method by consideration of 16 segment plants instead of 16 Kharitonov plants provides an elegant and efficient tool for finding all robustly stabilizing PID controllers for an interval system. The validity and relatively effortless application of presented theoretical concepts are demonstrated through a computation and simulation example in which the uncertain mathematical model of an experimental oblique wing aircraft is robustly stabilized.

  6. Vehicle active steering control research based on two-DOF robust internal model control

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Liu, Yahui; Wang, Fengbo; Bao, Chunjiang; Sun, Qun; Zhao, Youqun

    2016-07-01

    Because of vehicle's external disturbances and model uncertainties, robust control algorithms have obtained popularity in vehicle stability control. The robust control usually gives up performance in order to guarantee the robustness of the control algorithm, therefore an improved robust internal model control(IMC) algorithm blending model tracking and internal model control is put forward for active steering system in order to reach high performance of yaw rate tracking with certain robustness. The proposed algorithm inherits the good model tracking ability of the IMC control and guarantees robustness to model uncertainties. In order to separate the design process of model tracking from the robustness design process, the improved 2 degree of freedom(DOF) robust internal model controller structure is given from the standard Youla parameterization. Simulations of double lane change maneuver and those of crosswind disturbances are conducted for evaluating the robust control algorithm, on the basis of a nonlinear vehicle simulation model with a magic tyre model. Results show that the established 2-DOF robust IMC method has better model tracking ability and a guaranteed level of robustness and robust performance, which can enhance the vehicle stability and handling, regardless of variations of the vehicle model parameters and the external crosswind interferences. Contradiction between performance and robustness of active steering control algorithm is solved and higher control performance with certain robustness to model uncertainties is obtained.

  7. 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

  8. Robust Control of Multiterminal DC/AC Systems,

    DTIC Science & Technology

    1979-08-31

    ROBUST CONTROL OF MULTITEPR4INAL DC/AC SYSTENS V(N / ~by ,, Le-htomaki,-S.M. Chan, N.R SandellJr. ./,thans,. Earigf Laboratory for Informat/.n and...decades, dc power transmission has // The intent of this paper is to illustrate how the provided a viable alternative to ac in special applica- MTDC...uti- sion, asynchronous connection between power systems of lized to arrive at a reasonable, robust control different frequencies, and interconnection

  9. Controlled quantum dialogue robust against conspiring users

    NASA Astrophysics Data System (ADS)

    Kao, Shih-Hung; Hwang, Tzonelih

    2016-10-01

    This paper explores a new security problem in controlled quantum dialogue (CQD) protocols, where the communicants may try to conspire to communicate without the controller's permission. According to our survey, all the previous CQD protocols suffer from this attack. In order to resolve this problem, we also present an improvement protocol. The security analyses show that the improved scheme is secure under this and other well-known attacks.

  10. Robust predictive cruise control for commercial vehicles

    NASA Astrophysics Data System (ADS)

    Junell, Jaime; Tumer, Kagan

    2013-10-01

    In this paper we explore learning-based predictive cruise control and the impact of this technology on increasing fuel efficiency for commercial trucks. Traditional cruise control is wasteful when maintaining a constant velocity over rolling hills. Predictive cruise control (PCC) is able to look ahead at future road conditions and solve for a cost-effective course of action. Model- based controllers have been implemented in this field but cannot accommodate many complexities of a dynamic environment which includes changing road and vehicle conditions. In this work, we focus on incorporating a learner into an already successful model- based predictive cruise controller in order to improve its performance. We explore back propagating neural networks to predict future errors then take actions to prevent said errors from occurring. The results show that this approach improves the model based PCC by up to 60% under certain conditions. In addition, we explore the benefits of classifier ensembles to further improve the gains due to intelligent cruise control.

  11. Pupil Control Behavior, Classroom Robustness, and Self-Control: Public and Military High Schools Compared.

    ERIC Educational Resources Information Center

    Sartori, Mary Ann; Bauske, Terri; Lunenburg, Fred C.

    This study investigates students' perceptions of teachers' pupil control behavior, classroom robustness, and student self-control. Results reveal an association between humanistic pupil control behavior of teachers and high levels of classroom robustness, high levels of classroom robustness and high student self-control, and teacher humanism in…

  12. 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

  13. Networked Robust Predictive Control Systems Design with Packet Loss

    NASA Astrophysics Data System (ADS)

    Nguyen, Quang T.; Veselý, Vojtech; Kozáková, Alena; Pakshin, Pavel

    2014-01-01

    The paper addresses problem of designing a robust output feedback model predictive control for uncertain linear systems over networks with packet-loss. The packet-loss process is arbitrary and bounded by the control horizon of model predictive control. Networked predictive control systems with packet loss are modeled as switched linear systems. This enables us to apply the theory of switched systems to establish the stability condition. The stabilizing controller design is based on sufficient robust stability conditions formulated as a solution of bilinear matrix inequality. Finally, a benchmark numerical example-double integrator is given to illustrate the effectiveness of the proposed method.

  14. Design and tuning of robust PID controller for HVAC systems

    SciTech Connect

    Kasahara, Masato; Matsuba, Tadahiko; Kuzuu, Yoshiaki; Yamazaki, Takanori; Hashimoto, Yukihiro; Kamimura, Kazuyuki; Kurosu, Shigeru

    1999-07-01

    This paper concerns the development of a new design and tuning method for use with robust proportional-plus-integral-plus-derivative (PID) controllers that are commonly used in the heating, ventilating, and air-conditioning (HVAC) fields. The robust PID controller is designed for temperature control of a single-zone environmental space. Although the dynamics of environmental space are described by higher-order transfer functions, most HVAC plants are approximated by first-order lag plus deadtime systems. Its control performance is examined for this commonly approximated controlled plant. Since most HVAC plants are complex with nonlinearity, distributed parameters, and multivariables, a single set of PID gains does not necessarily yield a satisfactory control performance. For this reason, the PID controller must be designed as a robust control system considering model uncertainty caused by changes in characteristics of the plant. The PID gains obtained by solving a two-disk type of mixed sensitivity problem can be modified by contrast to those tuned by the traditional Ziegler-Nichols rule. The results, which are surprisingly simple, are given as linear functions of ratio of deadtime to time constant for robustness. The numerical simulation and the experiments on a commercial-size test plant for air conditioning suggest that the robust PID controller proposed in this paper is effective enough for practical applications.

  15. Randomised controlled trial of telemedicine for new neurological outpatient referrals.

    PubMed

    Chua, R; Craig, J; Wootton, R; Patterson, V

    2001-07-01

    To test the hypothesis that telemedicine for new patient referrals to neurological outpatients is as efficient and acceptable as conventional face to face consultation. A randomised controlled trial between two groups: face to face (FF) and telemedicine (TM). This study was carried out between a neurological centre and outlying clinics at two distant hospitals linked by identical medium cost commercial interactive video conferencing equipment with ISDN lines transmitting information at 384 kbits/s. The same two neurologists carried out both arms of the study. Of the 168 patients who were suitable for the study, 86 were randomised into the telemedicine group and 82 into the face to face group. Outcome measures were (1) consultation process: (a) number of investigations; (b) number of drugs prescribed; (c) number of patient reviews and (2) patient satisfaction: (a) confidence in consultation; (b) technical aspects of consultation; (c) aspects surrounding confidentiality. Diagnostic categories were also measured to check equivalence between the groups: these were structural neurological, structural non-neurological, non-structural, and uncertain. Diagnostic categories were similar (p>0.5) between the two groups. Patients in the telemedicine group had significantly more investigations (p=0.001). There was no difference in the number of drugs prescribed (p>0.5). Patients were generally satisfied with both types of consultation process except for concerns about confidentiality and embarrassment in the telemedicine group (p=0.017 and p=0.005 respectively). Telemedicine for new neurological outpatients is possible and feasible but generates more investigations and is less well accepted than face to face examination.

  16. Randomised controlled trial of telemedicine for new neurological outpatient referrals

    PubMed Central

    Chua, R; Craig, J; Wootton, R; Patterson, V

    2001-01-01

    OBJECTIVE—To test the hypothesis that telemedicine for new patient referrals to neurological outpatients is as efficient and acceptable as conventional face to face consultation.
METHODS—A randomised controlled trial between two groups: face to face (FF) and telemedicine (TM). This study was carried out between a neurological centre and outlying clinics at two distant hospitals linked by identical medium cost commercial interactive video conferencing equipment with ISDN lines transmitting information at 384 kbits/s. The same two neurologists carried out both arms of the study.
 Of the 168 patients who were suitable for the study, 86 were randomised into the telemedicine group and 82 into the face to face group. Outcome measures were (1) consultation process: (a) number of investigations; (b) number of drugs prescribed; (c) number of patient reviews and (2) patient satisfaction: (a) confidence in consultation; (b) technical aspects of consultation; (c) aspects surrounding confidentiality. Diagnostic categories were also measured to check equivalence between the groups: these were structural neurological, structural non-neurological, non-structural, and uncertain.
RESULTS—Diagnostic categories were similar (p>0.5) between the two groups. Patients in the telemedicine group had significantly more investigations (p=0.001). There was no difference in the number of drugs prescribed (p>0.5). Patients were generally satisfied with both types of consultation process except for concerns about confidentiality and embarrassment in the telemedicine group (p=0.017 and p=0.005 respectively).
CONCLUSION—Telemedicine for new neurological outpatients is possible and feasible but generates more investigations and is less well accepted than face to face examination.

 PMID:11413265

  17. Optimization-Based Robust Nonlinear Control

    DTIC Science & Technology

    2006-08-01

    50, no. 5, pp. 546-558, May 2005. 12. "A nested Matrosov theorem and persistency of excitation for uniform convergence in stable nonautonomous...stability for difference inclusions", C.M. Kellett and A.R. Teel, Systems & Control Letters, vol. 52, no. 2, pp. 395-405, August 2004. 24. " Matrosov theorem...2004 American Control Conference, pp. 1413--1418, Boston, MA, June/July 2004. 9 34. "A Matrosov theorem with an application to model reference adaptive

  18. Robust Control for the Mercury Laser Altimeter

    NASA Technical Reports Server (NTRS)

    Rosenberg, Jacob S.

    2006-01-01

    Mercury Laser Altimeter Science Algorithms is a software system for controlling the laser altimeter aboard the Messenger spacecraft, which is to enter into orbit about Mercury in 2011. The software will control the altimeter by dynamically modifying hardware inputs for gain, threshold, channel-disable flags, range-window start location, and range-window width, by using ranging information provided by the spacecraft and noise counts from instrument hardware. In addition, because of severe bandwidth restrictions, the software also selects returns for downlink.

  19. Stable, Robust Tracking by Sliding Mode Control,

    DTIC Science & Technology

    1987-05-01

    Linear Systems , Prentice-Hall, 1980. 9. O.M.E. El-Ghesawi, S.A. Billings and A.S.I. Zinober, Variable structure systems and system zeros, Proc. IEE...82, January 1987. 7. G.C. Verghese and T. Kailath, Rational matrix structure, IEEE Trans. Auto. Control, AC-26, 434-438, April 1981. 8. T. Kailath

  20. Robust control-based object tracking.

    PubMed

    Qu, Wei; Schonfeld, Dan

    2008-09-01

    This correspondence presents a video tracking framework using control-based observer design. It unifies several kernel-based approaches into a consistent theoretical framework by modeling tracking as a recursive inverse problem. The framework relies on observability theory to handle the "singularity" problem and provides explicit criteria for kernel design and dynamics evaluation.

  1. Quantitative Robust Control Engineering: Theory and Applications

    DTIC Science & Technology

    2006-09-01

    1992). Discrete quantitative feedback technique, Capítulo 16 en el libro : Digital Control Systems: theory, hardware, software, 2ª edicion. McGraw...Rasmussen S.J., Garcia-Sanz, M. (2001, 2005), Software de diseño del libro Quantitative Feedback Theory: Fundamentals and Applications. Edición 2ª. CRCPress

  2. 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.

  3. 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.

  4. Robust Control of Underactuated Manipulators: Analysis and Implementation

    DTIC Science & Technology

    1994-05-01

    Y Control of mechanical systems with second-order nonholonomic constraints: underactuated manipulators. Proc. of the 30th Conference on Decision and...any of a series of controllers fully developed in the literature for mechanical manipulators. Because the control of such a system is fully dependent...robust controller for underactuated manipulators. The control of such systems can be extended to the control problem of fault-tolerant robots, space

  5. Specificity and robustness in transcription control networks.

    PubMed

    Sengupta, Anirvan M; Djordjevic, Marko; Shraiman, Boris I

    2002-02-19

    Recognition by transcription factors of the regulatory DNA elements upstream of genes is the fundamental step in controlling gene expression. How does the necessity to provide stability with respect to mutation constrain the organization of transcription control networks? We examine the mutation load of a transcription factor interacting with a set of n regulatory response elements as a function of the factor/DNA binding specificity and conclude on theoretical grounds that the optimal specificity decreases with n. The predicted correlation between variability of binding sites (for a given transcription factor) and their number is supported by the genomic data for Escherichia coli. The analysis of E. coli genomic data was carried out using an algorithm suggested by the biophysical model of transcription factor/DNA binding. Complete results of the search for candidate transcription factor binding sites are available at http://www.physics.rockefeller.edu/~boris/public/search_ecoli.

  6. 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

  7. Unmodeled Dynamics in Robust Nonlinear Control

    DTIC Science & Technology

    2000-08-01

    friend- ship and technical expertise, including Nazir Atassi, Julio Braslavsky, Kenan Ezal, Sergio Galeani, Gene Grimm, Jay Hatfield, Hoss Hauksson...of nonlinear geometric methods was a remarkable achievement of the 1980’s, presented in the books by Isidori [25], Nijmeijer [67], Marino [63] and in...and other authors. Output-injection observers have been incorporated in observer-based control designs by Marino and Tomei [62, 63], Kanellakopoulos

  8. Robust adaptive kinematic control of redundant robots

    NASA Technical Reports Server (NTRS)

    Tarokh, M.; Zuck, D. D.

    1992-01-01

    The paper presents a general method for the resolution of redundancy that combines the Jacobian pseudoinverse and augmentation approaches. A direct adaptive control scheme is developed to generate joint angle trajectories for achieving desired end-effector motion as well as additional user defined tasks. The scheme ensures arbitrarily small errors between the desired and the actual motion of the manipulator. Explicit bounds on the errors are established that are directly related to the mismatch between actual and estimated pseudoinverse Jacobian matrix, motion velocity and the controller gain. It is shown that the scheme is tolerant of the mismatch and consequently only infrequent pseudoinverse computations are needed during a typical robot motion. As a result, the scheme is computationally fast, and can be implemented for real-time control of redundant robots. A method is incorporated to cope with the robot singularities allowing the manipulator to get very close or even pass through a singularity while maintaining a good tracking performance and acceptable joint velocities. Computer simulations and experimental results are provided in support of the theoretical developments.

  9. Low bandwidth robust controllers for flight

    NASA Technical Reports Server (NTRS)

    Biezad, Daniel J.; Chou, Hwei-Lan

    1992-01-01

    During the final reporting period (Jun. - Dec. 1992), analyses of the longitudinal and lateral flying qualities were made for propulsive-only flight control (POFC) of a Boeing 720 aircraft model. Performance resulting from compensators developed using Quantitative Feedback Theory (QFT) is documented and analyzed. This report is a first draft of a thesis to be presented by graduate student Hwei-Lan Chou. The final thesis will be presented to NASA when it is completed later this year. The latest landing metrics related to bandwidth criteria and based on the Neal-Smith approach to flying qualities prediction were used in developing performance criteria for the controllers. The compensator designs were tested on the NASA simulator and exhibited adequate performance for piloted flight. There was no significant impact of QFT on performance of the propulsive-only flight controllers in either the longitudinal or lateral modes of flight. This was attributed to the physical limits of thrust available and the engine rate of response, both of whiih severely limited the available bandwidth of the closed-loop system.

  10. A Robust Control Design Framework for Substructure Models

    NASA Technical Reports Server (NTRS)

    Lim, Kyong B.

    1994-01-01

    A framework for designing control systems directly from substructure models and uncertainties is proposed. The technique is based on combining a set of substructure robust control problems by an interface stiffness matrix which appears as a constant gain feedback. Variations of uncertainties in the interface stiffness are treated as a parametric uncertainty. It is shown that multivariable robust control can be applied to generate centralized or decentralized controllers that guarantee performance with respect to uncertainties in the interface stiffness, reduced component modes and external disturbances. The technique is particularly suited for large, complex, and weakly coupled flexible structures.

  11. Robust Control and Synchronization of Chaos

    DTIC Science & Technology

    2007-11-02

    parameters. In addition, we have set up a two-axis acousto - optic laser beam deflector that will be used to deliver control perturbations to the system at...a) (c) (b) ( d ) Figure 5.4: Dynamical behavior of the new source of chaotic optical frequency flucations. For low amplifier gain, the frequency of...PROGRESS REPORTS; SEE PAGE 2 FOR INTERIM PROGRESS REPORT INSTRUCTIONS. MEMORANDUM OF TRANSMITTAL U.S. Army Research Office ATTN: AMSRL-RO-BI (TR) P.O

  12. 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.

  13. 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.

  14. Efficacy of nonswallow nasogastric tube intubation: a randomised controlled trial.

    PubMed

    Fan, Luo; Liu, Qin; Gui, Li

    2016-11-01

    To prospectively identify the effect of the nonswallow procedure of nasogastric tube insertion. Nasogastric intubation is one of the most important and basic skills in treatment and nursing. Patients generally experience discomfort and encounter complications during this procedure. Thus, practitioners need a more convenient, effective, quicker and safer method to improve the performance of this procedure. This prospective randomised controlled trial was conducted from March to May 2014 in the four units of Gansun Province Hospital in Lanzhou, China. A total of 80 participants were randomly assigned to an experimental group (n = 40) and a control group (n = 40). Participants in the experimental group underwent a nonswallow procedure for nasogastric tube insertion. There were statistically significant differences in nasogastric tube insertion between the study groups. A marked increase in the success rate at first intubation as well as a markedly reduced occurrence of nausea, tearing, mucosal injury and changes in vital signs (i.e. heart rate, breath, systolic pressure) were observed compared with the control group. No differences in the success rates at second and third intubation were observed between the groups. The nonswallow procedure of nasogastric tube intubation relieves discomfort and ensures the safety of patients. Patients subjected to nasogastric intubation are more likely to benefit from the nonswallow procedure when nasogastric tube insertion is performed. © 2016 John Wiley & Sons Ltd.

  15. Stress debriefing after childbirth: a randomised controlled trial.

    PubMed

    Priest, Susan R; Henderson, Jenni; Evans, Sharon F; Hagan, Ronald

    2003-06-02

    To test whether critical incident stress debriefing after childbirth reduces the incidence of postnatal psychological disorders. Randomised single-blind controlled trial stratified for parity and delivery mode. Two large maternity hospitals in Perth. 1745 women who delivered healthy term infants between April 1996 and December 1997 (875 allocated to intervention and 870 to control group). An individual, standardised debriefing session based on the principles of critical incident stress debriefing carried out within 72 hours of delivery. Diagnosis of stress disorders or depression in the 12 months postpartum, using structured psychological interview and criteria of the Diagnostic and statistical manual of mental disorders, 4th edition. Follow-up information was available for 1730 women (99.1%), 482 of whom underwent psychological interview. There were no significant differences between control and intervention groups in scores on Impact of Events or Edinburgh Postnatal Depression Scales at 2, 6 or 12 months postpartum, or in proportions of women who met diagnostic criteria for a stress disorder (intervention, 0.6% v control, 0.8%; P = 0.58) or major or minor depression (intervention, 17.8% v control, 18.2%; relative risk [95% CI], 0.99 [0.87-1.11]) during the postpartum year. Nor were there differences in median time to onset of depression (intervention, 6 [interquartile range, 4-9] weeks v control, 4 [3-8] weeks; P = 0.84), or duration of depression (intervention, 24 [12-46] weeks v control, 22 [10-52] weeks; P = 0.98). There is a high prevalence of depression in women during the first year after childbirth. A session of midwife-led, critical incident stress debriefing was not effective in preventing postnatal psychological disorders, but had no adverse effects.

  16. 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.

  17. Robust adaptive control of MEMS triaxial gyroscope using fuzzy compensator.

    PubMed

    Fei, Juntao; Zhou, Jian

    2012-12-01

    In this paper, a robust adaptive control strategy using a fuzzy compensator for MEMS triaxial gyroscope, which has system nonlinearities, including model uncertainties and external disturbances, is proposed. A fuzzy logic controller that could compensate for the model uncertainties and external disturbances is incorporated into the adaptive control scheme in the Lyapunov framework. The proposed adaptive fuzzy controller can guarantee the convergence and asymptotical stability of the closed-loop system. The proposed adaptive fuzzy control strategy does not depend on accurate mathematical models, which simplifies the design procedure. The innovative development of intelligent control methods incorporated with conventional control for the MEMS gyroscope is derived with the strict theoretical proof of the Lyapunov stability. Numerical simulations are investigated to verify the effectiveness of the proposed adaptive fuzzy control scheme and demonstrate the satisfactory tracking performance and robustness against model uncertainties and external disturbances compared with conventional adaptive control method.

  18. 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.

  19. Interpolation techniques in robust constrained model predictive control

    NASA Astrophysics Data System (ADS)

    Kheawhom, Soorathep; Bumroongsri, Pornchai

    2017-05-01

    This work investigates interpolation techniques that can be employed on off-line robust constrained model predictive control for a discrete time-varying system. A sequence of feedback gains is determined by solving off-line a series of optimal control optimization problems. A sequence of nested corresponding robustly positive invariant set, which is either ellipsoidal or polyhedral set, is then constructed. At each sampling time, the smallest invariant set containing the current state is determined. If the current invariant set is the innermost set, the pre-computed gain associated with the innermost set is applied. If otherwise, a feedback gain is variable and determined by a linear interpolation of the pre-computed gains. The proposed algorithms are illustrated with case studies of a two-tank system. The simulation results showed that the proposed interpolation techniques significantly improve control performance of off-line robust model predictive control without much sacrificing on-line computational performance.

  20. Exercise therapy for osteoporosis: results of a randomised controlled trial.

    PubMed Central

    Preisinger, E; Alacamlioglu, Y; Pils, K; Bosina, E; Metka, M; Schneider, B; Ernst, E

    1996-01-01

    OBJECTIVE: To define the effects of therapeutic exercise on bone density and back complaints. METHODS: A randomised controlled trial with parallel groups was conducted in an outpatient clinic, Medical School, University of Vienna. Ninety two sedentary post-menopausal women with back problems were randomly allocated to either exercise (groups 1 and 2) or control (group 3, no exercise, n = 31); the exercise group was retrospectively subdivided into compliant (group 1, n = 27) and not fully compliant patients (group 2, n = 34). Regular, initially supervised therapeutic exercise aimed at restoring biomechanical function was performed for four years. Bone density in the forearm was measured by single photon absorptiometry at entry and after four years; subjective back complaints were documented. RESULTS: A significant decrease in bone density was observed in groups 2 and 3; no change was noted in group 1; back complaints decreased in group 1 only. CONCLUSIONS: Sedentary postmenopausal women may benefit from regular long term therapeutic exercise in terms of subjective back complaints and slowed loss of bone mass. PMID:8889112

  1. Robust Multivariable Controller Design via Implicit Model-Following Methods.

    DTIC Science & Technology

    1983-12-01

    HD-Ri38 309 ROBUST MULTIVARIABLE CONTROLLER DESIGN VIA IMPLICIT 1/4 MODEL-FOLLOWING METHODS(U) AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL...aaS. a%. 1 .111 I Q~ 18 0 ROBUST MULTIVARIABLE CONTROLLER DESIGN -~ :VIA IMPLICIT MODEL-FOLLOWING METHODS ’.% THESIS , AFIT/GE/EE/83D-48 William G... CONTROLLER DESIGN VIA IMPLICIT MODEL-FOLLOWING METHODS THESIS AFIT/GE/EE/83D-48 William G. Miller Capt USAF ,. Approved for pubi release; distribution

  2. Robust control of a parallel hybrid drivetrain with a CVT

    SciTech Connect

    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.

  3. 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.

  4. Robust decentralized controller design for UPFC using μ-synthesis

    NASA Astrophysics Data System (ADS)

    Taher, Seyed Abbas; Akbari, Shahabeddin; Abdolalipour, Ali; Hematti, Reza

    2010-08-01

    In this paper a new method based on structured singular value ( μ-synthesis) is proposed for the robust decentralized unified power flow controller (UPFC) design. To achieve decentralization, using the Schauder fixed point theorem the synthesis and analysis of multi-input multi-output (MIMO) control system is transformed into a set of equivalent multi-input single-output (MISO) control system. To cope with power system uncertainties μ-synthesis technique is being used for designing of UPFC controllers. The proposed μ-based controller has a decentralized scheme which has the advantage of reduction in the controller complexity and suitability for practical implementation. The effectiveness of the proposed control strategy on damping low frequency oscillations is evaluated under different operating conditions and compared with the conventional controller to demonstrate its robust performance through nonlinear simulation and some performance indices.

  5. 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.

  6. Robustness with observers. [linear optimal feedback control systems

    NASA Technical Reports Server (NTRS)

    Doyle, J. C.; Stein, G.

    1979-01-01

    The paper describes an adjustment procedure for observer-based linear control systems which asymptotically achieves the same loop transfer functions (and hence the same relative stability, robustness, and disturbance rejection properties) as full-state feedback control implementations. Full-state loop-transfer properties can be recovered asymptotically if the plant is minimum phase; this occurs at the expense of noise performance.

  7. Guidance and Control for Mars Atmospheric Entry: Adaptivity and Robustness

    NASA Technical Reports Server (NTRS)

    Lu, Wei-Min; Bayard, David S.

    1997-01-01

    In this paper, we address the atmospheric entry guidance and control problem for Mars precision landing. The guidance and control design is based on the principle of tracking a reference drag versus velocity profile in the entry flight corridor, which is determined by physical constraints of the flight. An integrated adaptive/robust control approach to atmospheric entry guidance and control is introduced to deal with different uncertainties.

  8. A decentralized adaptive robust method for chaos control.

    PubMed

    Kobravi, Hamid-Reza; Erfanian, Abbas

    2009-09-01

    This paper presents a control strategy, which is based on sliding mode control, adaptive control, and fuzzy logic system for controlling the chaotic dynamics. We consider this control paradigm in chaotic systems where the equations of motion are not known. The proposed control strategy is robust against the external noise disturbance and system parameter variations and can be used to convert the chaotic orbits not only to the desired periodic ones but also to any desired chaotic motions. Simulation results of controlling some typical higher order chaotic systems demonstrate the effectiveness of the proposed control method.

  9. Chest physical therapy for children hospitalised with acute pneumonia: a randomised controlled trial.

    PubMed

    Paludo, C; Zhang, L; Lincho, C S; Lemos, D V; Real, G G; Bergamin, J A

    2008-09-01

    The indication for chest physical therapy as an adjunct to the treatment of children hospitalised with acute pneumonia remains controversial and there is a lack of robust scientific evidence for the effectiveness of this modality in these patients. A randomised controlled trial was conducted in two tertiary hospitals in southern Brazil. Children aged 29 days to 12 years hospitalised with pneumonia between February and October 2006 were recruited; 51 were randomly allocated to the intervention group (chest physical therapy plus standard treatment for pneumonia) and 47 to the control group (standard treatment for pneumonia alone). The primary outcome was time to clinical resolution. The secondary outcomes were length of stay in hospital and duration of respiratory symptoms and signs. There were no significant differences in terms of median time to clinical resolution (4.0 vs 4.0 days, p = 0.84) and median length of hospital stay (6.0 vs 6.0 days, p = 0.76) between the intervention and control groups. The intervention group had a longer median duration of coughing (5.0 vs 4.0 days, p = 0.04) and of rhonchi on lung auscultation (2.0 vs 0.5 days, p = 0.03) than the control group. Chest physical therapy as an adjunct to standard treatment does not hasten clinical resolution of children hospitalised with acute pneumonia and may prolong duration of coughing and rhonchi.

  10. Optimal robust motion controller design using multiobjective genetic algorithm.

    PubMed

    Sarjaš, Andrej; Svečko, Rajko; Chowdhury, Amor

    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.

  11. 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

  12. Strategies for Increasing Recruitment to Randomised Controlled Trials: Systematic Review

    PubMed Central

    Caldwell, Patrina H. Y.; Hamilton, Sana; Tan, Alvin; Craig, Jonathan C.

    2010-01-01

    Background Recruitment of participants into randomised controlled trials (RCTs) is critical for successful trial conduct. Although there have been two previous systematic reviews on related topics, the results (which identified specific interventions) were inconclusive and not generalizable. The aim of our study was to evaluate the relative effectiveness of recruitment strategies for participation in RCTs. Methods and Findings A systematic review, using the PRISMA guideline for reporting of systematic reviews, that compared methods of recruiting individual study participants into an actual or mock RCT were included. We searched MEDLINE, Embase, The Cochrane Library, and reference lists of relevant studies. From over 16,000 titles or abstracts reviewed, 396 papers were retrieved and 37 studies were included, in which 18,812 of at least 59,354 people approached agreed to participate in a clinical RCT. Recruitment strategies were broadly divided into four groups: novel trial designs (eight studies), recruiter differences (eight studies), incentives (two studies), and provision of trial information (19 studies). Strategies that increased people's awareness of the health problem being studied (e.g., an interactive computer program [relative risk (RR) 1.48, 95% confidence interval (CI) 1.00–2.18], attendance at an education session [RR 1.14, 95% CI 1.01–1.28], addition of a health questionnaire [RR 1.37, 95% CI 1.14–1.66]), or a video about the health condition (RR 1.75, 95% CI 1.11–2.74), and also monetary incentives (RR1.39, 95% CI 1.13–1.64 to RR 1.53, 95% CI 1.28–1.84) improved recruitment. Increasing patients' understanding of the trial process, recruiter differences, and various methods of randomisation and consent design did not show a difference in recruitment. Consent rates were also higher for nonblinded trial design, but differential loss to follow up between groups may jeopardise the study findings. The study's main limitation was the necessity of

  13. Transvenous neurostimulation for central sleep apnoea: a randomised controlled trial.

    PubMed

    Costanzo, Maria Rosa; Ponikowski, Piotr; Javaheri, Shahrokh; Augostini, Ralph; Goldberg, Lee; Holcomb, Richard; Kao, Andrew; Khayat, Rami N; Oldenburg, Olaf; Stellbrink, Christoph; Abraham, William T

    2016-09-03

    Central sleep apnoea is a serious breathing disorder associated with poor outcomes. The remedé system (Respicardia Inc, Minnetonka, MN, USA) is an implantable device which transvenously stimulates a nerve causing diaphragmatic contraction similar to normal breathing. We evaluated the safety and effectiveness of unilateral neurostimulation in patients with central sleep apnoea. We recruited patients from 31 hospital-based centres in Germany, Poland, and the USA in this prospective, multicentre, randomised trial. Participants had to have been medically stable for at least 30 days and have received appropriate guideline recommended therapy, be aged at least 18 years, be expected to tolerate study procedures, and willing and able to comply with study requirements. Eligible patients with an apnoea-hypopnoea index (AHI) of at least 20 events per h, tested by a polysomnography, underwent device implantation and were randomly assigned (1:1) by a computer-generated method stratified by site to either stimulation (treatment) or no stimulation (control) for 6 months. The primary effectiveness endpoint in the intention-to-treat population was the comparison of the proportions of patients in the treatment versus control groups achieving a 50% or greater AHI reduction from baseline to 6 months, measured by a full-night polysomnography assessed by masked investigators in a core laboratory. The primary safety endpoint of 12-month freedom from serious adverse events related to the procedure, system, or therapy was evaluated in all patients. This trial is active, but not recruiting, and is registered with ClinicalTrials.gov (NCT01816776). Between April 17, 2013, and May 28, 2015, we randomly assigned 151 eligible patients to the treatment (n=73) or control (n=78) groups. In the analysis of the intention-to-treat population, significantly more patients in the treatment group (35 [51%] of 68) had an AHI reduction from baseline of 50% or greater at 6 months than had those in the

  14. Panax ginseng in randomised controlled trials: a systematic review.

    PubMed

    Shergis, Johannah L; Zhang, Anthony L; Zhou, Wenyu; Xue, Charlie C

    2013-07-01

    Panax ginseng C.A. Meyer is a common herb with many purported health benefits. However, there is no conclusive evidence supporting its use in the treatment of any particular disease. We conducted a systematic review to evaluate randomised controlled trials. Four English databases were searched with no publication date restriction. Included studies evaluated P. ginseng in patients with any type of disease or in healthy individuals. We assessed the quality of studies using the Cochrane risk of bias tool. Of the 475 potentially relevant studies, 65 met the inclusion criteria. These studies examined P. ginseng's effects on psychomotor performance (17 studies), physical performance (ten), circulatory system (eight), glucose metabolism (six), the respiratory system (five), erectile dysfunction (four), immunomodulation (four), quality of life/mood (four), antioxidant function (two), cancer (two), menopausal symptoms (two) and dry mouth (one). The risk of bias was unclear in most studies. Authors evaluated adverse events in 40 studies, with 135 minor events and no serious adverse events reported. P. ginseng shows promising results for improving glucose metabolism and moderating the immune response. This may have implications for several diseases including type 2 diabetes and chronic respiratory conditions. Further studies are needed to explore P. ginseng's potential as an effective treatment for these and other health conditions.

  15. Microfractures at the rotator cuff footprint: a randomised controlled study.

    PubMed

    Osti, Leonardo; Del Buono, Angelo; Maffulli, Nicola

    2013-11-01

    Microfractures at the footprint may be a potential additional source of growth factor and enhance the tendon healing at the bone-tendon junction when repairing rotator cuff tears. Fifty-seven patients who underwent shoulder arthroscopy for repair of complete rotator cuff tears were randomly divided into two groups, using a block randomisation procedure. Patients underwent microfracture at the footprint in the treatment group. The patients in the control group (n = 29) did not receive that treatment. All patients had the same post-operative rehabilitation protocol. The two groups were homogeneous. There was a significant improvement from baseline to the last minimum follow-up of two years. At three months from the index procedure, visual analogue scale (VAS), range of motion (ROM) and University of California at Los Angeles (UCLA) and Constant scores were significantly better in group 1 than in group 2 (P < .05). At the last follow-up (minimum two years), clinical and functional outcomes were further improved in both the groups but inter-group differences were not significant. No technique-related complications were recorded. Microfractures at the footprint are simple, safe, inexpensive and effective at producing less pain in the short term in patients who undergo rotator cuff repair, but at two years they do not result in significantly different outcomes, either clinically or at imaging, compared to traditional rotator cuff repair.

  16. A randomised controlled trial of the efficacy of supported employment.

    PubMed

    Hoffmann, H; Jäckel, D; Glauser, S; Kupper, Z

    2012-02-01

      Although numerous randomised controlled trials indicated the superiority of supported employment (SE), we still have too little evidence that SE is more effective than traditional vocational rehabilitation programmes (TVR) in Western European countries with highly developed social security and welfare systems, sophisticated rehabilitation programmes and high thresholds to the open labour market. The aim of this study is to prove the efficacy of SE in Switzerland.   Following a 2-week intake assessment, 100 unemployed persons with stabilised severe mental illness (SMI) were randomly assigned to either the SE programme (n=46) or to the most viable locally available TVR (n=54). Follow-up lasted 24 months.   After the first year, the rate of competitive employment reached a mean level of 48.2% in the SE group and of 18.5% in the TVR group. 58.7% of the SE group were ever competitively employed as opposed to 25.9% of the TVR group. In the second year, SE group participants were competitively employed for 24.5 weeks as compared with 10.2 in the TVR group. The groups showed no significant differences in the non-vocational outcome criteria.   The SE programme in Switzerland also proved more effective than TVR and seems to be applicable to the socio-economic context of Western European countries. © 2011 John Wiley & Sons A/S.

  17. 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.

  18. Analysis the robustness of control systems based on disturbance observer

    NASA Astrophysics Data System (ADS)

    Sariyildiz, Emre; Ohnishi, Kouhei

    2013-10-01

    Disturbance observer (DOB) estimates the system disturbances by using the inverse of the nominal plant model and a low pass filter (LPF). Although the LPF provides the properness in the inner-loop, it is the main design constraint of the control systems based on DOB. The bandwidth of the LPF is designed as high as possible so that the DOB can estimate the disturbances in a wider frequency range. However, its bandwidth is limited by noise and robustness of the system. The robustness limitation is directly related with the robustness analysis methods, and they significantly affect the performance of the DOB based control systems. In this paper, three different robustness analysis methods are implemented into the DOB based control systems, and the relation between the robustness of the system and bandwidth of DOB is clearly explained. The conservatism, which is the main drawback of the conventional analysis methods, on the bandwidth of DOB is removed by proposing a new real parametric uncertainty based analysis method. The proposed methods are compared in detail, and simulation results are given to show the validation.

  19. Robust and reliable control via quadratic Lyapunov functions

    NASA Astrophysics Data System (ADS)

    Alt, Terry Robert

    In this dissertation we present a new approach to design robust and reliable controllers. Our results are used to find control laws for systems that are subject to (1) real polytopic and norm bounded uncertainties, (2) actuator and sensor variations and (3) actuator and sensor failure. In addition, we present conditions that can be added to the control design problem to constrain the controller to be stable or strictly positive real, further strengthening the robustness and reliability of the control design. The basic framework relies on the use of quadratic Lyapunov functions to accommodate potentially time varying uncertainty. Conditions are derived that, when satisfied, allow a robust control design to be obtained by performing two convex optimizations. These controllers recover the performance robustness of either state feedback or full information controllers. Sufficient conditions are presented that remove the non-convexity in terms of the control design variables. This allows a robust control design to be obtained by solving a set of linear matrix inequalities. These general robustness results are then applied to the reliability problem. Actuator and sensor variations are modeled using real polytopic uncertainties. It is shown that under some simplifying assumptions the state feedback problem reduces to a single linear matrix inequality. It also shows that the Riccati equations for standard LQR and Hsb{infty} need only a slight modification to obtain a control law that is reliable with respect to actuator variability. For the output feedback case, convex conditions are presented that yield controllers which are reliable to actuator and sensor variations. Utilizing the simultaneous Lyapunov function approach, we further extend these results to include actuator or sensor failure. Additionally, when applicable, stronger reliability guaranties may be obtained by constraining the controller to be strictly positive real. This guarantees stability for positive real

  20. Increasing child pedestrian and cyclist visibility: cluster randomised controlled trial.

    PubMed

    Mulvaney, C A; Kendrick, D; Watson, M C; Coupland, C A C

    2006-04-01

    Visibility aids have the potential to reduce child pedestrian and cyclist injury but scarce data exist relating to their use or to interventions for increasing visibility aid use among children. This cluster randomised controlled trial was designed to assess the use of free visibility aids one and eight weeks after their provision among primary school children in Nottingham, UK. One class from each of 20 schools representing 377 children aged 7, 8, and 9 years old participated in the trial and were randomly assigned to treatment and control arms. Children in the intervention arm received two visibility aids, namely, a reflective and fluorescent slap wrap (an item that can be worn around an arm or trouser leg and is readily removed), and a reflective durable sticker in addition to educational material on the importance of being seen in the dark. Observers visited schools to observe use of reflective and fluorescent slap wraps, stickers, piping and patches on coats, and bags at baseline and at one and eight weeks after distribution of the visibility aids. The study used random effects logistic regression to calculate odds ratios (OR) and confidence intervals (CI). The results showed that children provided with free visibility aids were significantly more likely to use any visibility aid at one week (adjusted OR 59.5, 95% CI 18.5 to 191.0) and eight weeks (adjusted OR 5.9, 95% CI 3.4 to 10.4) after distribution than children in the control arm. Providing free visibility aids and an educational booklet on road safety significantly increases use of visibility aids for up to eight weeks during the winter among primary school children. On the basis of an eight week follow up trial in Nottingham of 20 classes of children aged 7 to 9 years old, these results suggest that campaigns providing free visibility aids to primary school children should be encouraged.

  1. Motivational interviewing for modifying diabetes risk: a randomised controlled trial

    PubMed Central

    Greaves, Colin J; Middlebrooke, Andrew; O'Loughlin, Lucy; Holland, Sandra; Piper, Jane; Steele, Anna; Gale, Tracy; Hammerton, Fenella; Daly, Mark

    2008-01-01

    Background Around 10–15% of adults aged over 40 years have pre-diabetes, which carries a high risk of progression to type 2 diabetes. Intensive lifestyle intervention reduces progression by as much as 58%. However, the cost and personnel requirements of these interventions are major obstacles to delivery in NHS primary care. Aim To assess the effectiveness of a low-cost intervention, delivered in primary care by non-NHS staff, to reduce the risk of diabetes through weight loss and physical activity. Design of study Pragmatic single-blind randomised controlled trial with researchers and statistician blinded to group allocation. Setting UK primary care. Method One-hundred and forty-one participants with a body mass index of 28 kg/m2 or more, but without diabetes or heart disease, received either information leaflets or individual behavioural counselling using motivational interviewing techniques. The intervention was delivered by five counsellors recruited from the local community. The primary outcomes were the proportions of participants meeting predefined targets for weight loss (5%) and moderate physical activity (150 minutes/week) after 6 months. Results Using intention-to-treat analysis, more people in the intervention group achieved the weight-loss target (24% versus 7% for controls; odds ratio [OR] = 3.96; 95% confidence interval [Cl] = 1.4 to 11.4; number needed to treat [NNT] = 6.1 (95% Cl = 4 to 21). The proportion achieving the physical activity target did not increase significantly (38% versus 28% for controls; OR = 1.6; 95% Cl = 0.7 to 3.8). Conclusion Short-term weight loss, at a level which, if sustained, is clinically meaningful for reducing diabetes risk, is achievable in primary care, without excessive use of NHS monetary or personnel resources. PMID:18682011

  2. Increasing child pedestrian and cyclist visibility: cluster randomised controlled trial

    PubMed Central

    Mulvaney, C A; Kendrick, D; Watson, M C; Coupland, C A C

    2006-01-01

    Study objective Visibility aids have the potential to reduce child pedestrian and cyclist injury but scarce data exist relating to their use or to interventions for increasing visibility aid use among children. This cluster randomised controlled trial was designed to assess the use of free visibility aids one and eight weeks after their provision among primary school children in Nottingham, UK. Design One class from each of 20 schools representing 377 children aged 7, 8, and 9 years old participated in the trial and were randomly assigned to treatment and control arms. Children in the intervention arm received two visibility aids, namely, a reflective and fluorescent slap wrap (an item that can be worn around an arm or trouser leg and is readily removed), and a reflective durable sticker in addition to educational material on the importance of being seen in the dark. Observers visited schools to observe use of reflective and fluorescent slap wraps, stickers, piping and patches on coats, and bags at baseline and at one and eight weeks after distribution of the visibility aids. The study used random effects logistic regression to calculate odds ratios (OR) and confidence intervals (CI). Main result The results showed that children provided with free visibility aids were significantly more likely to use any visibility aid at one week (adjusted OR 59.5, 95% CI 18.5 to 191.0) and eight weeks (adjusted OR 5.9, 95% CI 3.4 to 10.4) after distribution than children in the control arm. Conclusions Providing free visibility aids and an educational booklet on road safety significantly increases use of visibility aids for up to eight weeks during the winter among primary school children. On the basis of an eight week follow up trial in Nottingham of 20 classes of children aged 7 to 9 years old, these results suggest that campaigns providing free visibility aids to primary school children should be encouraged. PMID:16537347

  3. Optical Model Reduction and Robust Feedback Control for Aerodynamics

    DTIC Science & Technology

    2010-03-29

    LQR ) control formulation, roughly 1210 Riccati unknowns need to be calculated for a discretized flow model describing 610 states. Existing computing...1 Optimal Model Reduction and Robust Feedback Control for Aerodynamics AFoSR Grant AF-FA9550-08-1-0450 Seddik M. Djouadi Department of...methods of model reduction that integrate feedback active flow control with applications to nonlinear convection and turbulent flows governed by

  4. Robust Semi-Active Ride Control under Stochastic Excitation

    DTIC Science & Technology

    2014-01-01

    5] M. S. Kumar and S. Vijayarangan, "Design of LQR Controller for Active Suspension System," Indian Journal of Engineering and Materials Sciences...UNCLASSIFIED: Distribution Statement A. Approved for public release Type Paper Number Here Robust Semi-Active Ride Control under Stochastic...information. It will be pulled from participant tab in MyTechZone) Copyright © 2014 SAE International Abstract Ride control of military vehicles is

  5. 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.

  6. Robust control systems design by H-infinity optimization theory

    NASA Technical Reports Server (NTRS)

    Chang, B. C.; Li, X. P.; Banda, S. S.; Yeh, H. H.

    1991-01-01

    In this paper, step-by-step procedures of applying the H-infinity theory to robust control systems design are given. The objective of the paper is to eliminate the possible difficulties a control engineer may encounter in applying H-infinity control theory and to clear up some misconceptions about H-infinity theory like high-gain controller and numerical obstacles, etc. An efficient algorithm is used to compute the optimal H-infinity norm. The Glover and Doyle (1988) controller formulas are slightly modified and used to construct an optimal controller without any numerical difficulties.

  7. Robust association of the LPA locus with LDLc lowering response to statin treatment in a meta-analysis of 30,467 individuals from both randomised control trials and observational studies and association with coronary artery disease outcome during statin treatment

    PubMed Central

    Donnelly, Louise A; van Zuydam, Natalie R; Zhou, Kaixin; Tavendale, Roger; Carr, Fiona; Maitland-van der Zee, Anke H; Leusink, Maarten; de Boer, Anthonius; Doevendans, Pieter A; WAsselbergs, Folkert; Morris, Andrew D; Pearson, Ewan R; Klungel, Olaf H; Doney, Alex SF; Palmer, Colin NA

    2014-01-01

    Objectives The LPA SNP rs10455872 has been associated with low density lipoprotein cholesterol (LDLc) lowering response to statins in several randomised control trials (RCTs) and is a known coronary artery disease (CAD) marker. However it is unclear what residual risk of CAD this marker may have during statin treatment. Methods Using electronic medical records linked to the GoDARTS genotyped population we identified over 8000 patients on statins in Tayside, Scotland. Results We replicated the findings of the RCTs, with the G allele of rs10455872 being associated with a 0.10mmol/l per allele poorer reduction in LDLc in response to statin treatment, and conducted a meta-analysis with previously published RCTs (P=1.46×10−29, n=30,467). We demonstrate an association between rs10455872 and CAD in statin treated individuals and have replicated this finding in the Utrecht Cardiovascular Pharmacogenetics Study (combined odds ratio 1·41, 95% CI 1.17-1.68, P=4.5×10−5, n=8822) suggesting that statin treatment does not abrogate this well-established genetic risk for CAD. Furthermore in a Cox proportional hazards model with LDLc measured time dependently we demonstrated the relationship between CAD and rs10455872 was independent of LDLc during statin treatment. Conclusion Individuals with the G allele of rs10455872, which represents approximately 1 in 7 patients, have a higher risk of CAD than the majority of the population even after treatment with statins, and therefore represent a vulnerable group requiring an alternative medication in addition to statin treatment. PMID:23903772

  8. A new robust control for minirotorcraft unmanned aerial vehicles.

    PubMed

    Mokhtari, M Rida; Cherki, Brahim

    2015-05-01

    This paper presents a new robust control based on finite-time Lyapunov stability controller and proved with backstepping method for the position and the attitude of a small rotorcraft unmanned aerial vehicle subjected to bounded uncertainties and disturbances. The dynamical motion equations are obtained by the Newton-Euler formalism. The proposed controller combines the advantage of the backstepping approach with finite-time convergence techniques to generate a control laws to guarantee the faster convergence of the state variables to their desired values in short time and compensate for the bounded disturbances. A formal proof of the closed-loop stability and finite-time convergence of tracking errors is derived using the Lyapunov function technique. Simulation results are presented to corroborate the effectiveness and the robustness of the proposed control method. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  9. A robust composite nonlinear control scheme for servomotor speed regulation

    NASA Astrophysics Data System (ADS)

    Huang, Yanwei; Cheng, Guoqing

    2015-01-01

    A parameterised design of robust composite nonlinear controller is proposed for typical second-order servo systems subject to unknown constant disturbance and control input saturation. The control law consists of a linear feedback part for achieving fast response, a nonlinear feedback part for suppressing the overshoot, and a disturbance-compensation mechanism for erasing the steady-state error. An extended state observer is adopted to estimate the unknown disturbance. The closed-loop stability is analysed theoretically. The control scheme is applied to the speed regulation of permanent magnet synchronous motor, and numerical simulations are carried out. The results confirm that the proposed control scheme can achieve fast, smooth, and accurate speed regulation, and has a certain degree of robustness with respect to the amplitude of disturbances and the perturbations of system parameters.

  10. 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

  11. Robust Neural Sliding Mode Control of Robot Manipulators

    NASA Astrophysics Data System (ADS)

    Hiep, Nguyen Tran; cat, Pham Thuong

    2009-03-01

    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

  12. Robust Neural Sliding Mode Control of Robot Manipulators

    SciTech Connect

    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.

  13. 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.

  14. 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.

  15. Robust model-based controller synthesis for the SCOLE configuration

    NASA Technical Reports Server (NTRS)

    Armstrong, E. S.; Joshi, S. M.; Stewart, E. J.

    1988-01-01

    The design of a robust compensator is considered for the SCOLE configuration using a frequency-response shaping technique based on the LQG/LTR algorithm. Results indicate that a tenth-order compensator can be used to meet stability-performance-robustness conditions for a 26th-order SCOLE model without destabilizing spillover effects. Since the SCOLE configuration is representative of many proposed spaceflight experiments, the results and design techniques employed potentially should be applicable to a wide range of large space structure control problems.

  16. Geometric quantum gates that are robust against stochastic control errors

    SciTech Connect

    Zhu Shiliang; Zanardi, Paolo

    2005-08-15

    The realistic application of geometric quantum computation is crucially dependent on an unproved robustness conjecture, claiming that geometric quantum gates are more resilient against random noise than dynamic gates. We propose a suitable model that allows a direct and fair comparison between geometrical and dynamical operations. In the presence of stochastic control errors we find that the maximum of gate fidelity corresponds to quantum gates with a vanishing dynamical phase. This is a clear evidence for the robustness of nonadiabatic geometric quantum computation. The predictions here presented can be experimentally tested in almost all of the already existing quantum computer candidates.

  17. Immunosuppression for progressive membranous nephropathy: a UK randomised controlled trial

    PubMed Central

    Howman, Andrew; Chapman, Tracey L; Langdon, Maria M; Ferguson, Caroline; Adu, Dwomoa; Feehally, John; Gaskin, Gillian J; Jayne, David RW; O'Donoghue, Donal; Boulton-Jones, Michael; Mathieson, Peter W

    2013-01-01

    Summary Background Membranous nephropathy leads to end-stage renal disease in more than 20% of patients. Although immunosuppressive therapy benefits some patients, trial evidence for the subset of patients with declining renal function is not available. We aimed to assess whether immunosuppression preserves renal function in patients with idiopathic membranous nephropathy with declining renal function. Methods This randomised controlled trial was undertaken in 37 renal units across the UK. We recruited patients (18–75 years) with biopsy-proven idiopathic membranous nephropathy, a plasma creatinine concentration of less than 300 μmol/L, and at least a 20% decline in excretory renal function measured in the 2 years before study entry, based on at least three measurements over a period of 3 months or longer. Patients were randomly assigned (1:1:1) by a random number table to receive supportive treatment only, supportive treatment plus 6 months of alternating cycles of prednisolone and chlorambucil, or supportive treatment plus 12 months of ciclosporin. The primary outcome was a further 20% decline in renal function from baseline, analysed by intention to treat. The trial is registered as an International Standard Randomised Controlled Trial, number 99959692. Findings We randomly assigned 108 patients, 33 of whom received prednisolone and chlorambucil, 37 ciclosporin, and 38 supportive therapy alone. Two patients (one who received ciclosporin and one who received supportive therapy) were ineligible, so were not included in the intention-to-treat analysis, and 45 patients deviated from protocol before study end, mostly as a result of minor dose adjustments. Follow up was until primary endpoint or for minimum of 3 years if primary endpoint was not reached. Risk of further 20% decline in renal function was significantly lower in the prednisolone and chlorambucil group than in the supportive care group (19 [58%] of 33 patients reached endpoint vs 31 [84%] of 37, hazard

  18. 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.

  19. Variable Neural Adaptive Robust Control: A Switched System Approach

    SciTech Connect

    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 piecewise quadratic Lyapunov function. The performance of the proposed variable neural adaptive robust controllers is illustrated with simulations.

  20. Mitigation of Remedial Action Schemes by Decentralized Robust Governor Control

    SciTech Connect

    Elizondo, Marcelo A.; Marinovici, Laurentiu D.; Lian, Jianming; Kalsi, Karanjit; Du, Pengwei

    2014-04-15

    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 this 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.

  1. Vitamin E supplementation and macular degeneration: randomised controlled trial

    PubMed Central

    Taylor, Hugh R; Tikellis, Gabriella; Robman, Luba D; McCarty, Catherine A; McNeil, John J

    2002-01-01

    Objective To determine whether vitamin E supplementation influences the incidence or rate of progression of age related maculopathy (AMD). Design Prospective randomised placebo controlled clinical trial. Setting An urban study centre in a residential area supervised by university research staff. Participants 1193 healthy volunteers aged between 55 and 80 years; 73% completed the trial on full protocol. Interventions Vitamin E 500 IU or placebo daily for four years. Main outcome measures Primary outcome: development of early age related macular degeneration in retinal photographs. Other measures included alternative definitions of age related macular degeneration, progression, changes in component features, visual acuity, and visual function Results The incidence of early age related macular degeneration (early AMD 3) was 8.6% in those receiving vitamin E versus 8.1% in those on placebo (relative risk 1.05, 95% confidence interval 0.69 to 1.61). For late disease the incidence was 0.8% versus 0.6% (1.36, 0.67 to 2.77). Further analysis showed no consistent differences in secondary outcomes. Conclusion Daily supplement with vitamin E supplement does not prevent the development or progression of early or later stages of age related macular degeneration. What is already known on this topicAge related macular degeneration is the leading cause of loss of vision and blindness in elderly people; for people aged ⩾90 years, two out of every three will be affected and one in four will become blindCurrently, there are no methods of prevention or treatment in most cases, though a third of cases are due to cigarette smokingAntioxidant vitamins have been suggested as a possible preventionWhat this study addsDaily supplementation with 500 mg vitamin E for four years did not alter the incidence or progression of AMD PMID:12098721

  2. Providing child safety equipment to prevent injuries: randomised controlled trial.

    PubMed

    Watson, Michael; Kendrick, Denise; Coupland, Carol; Woods, Amanda; Futers, Deb; Robinson, Jean

    2005-01-22

    To assess the effectiveness of safety advice and safety equipment in reducing unintentional injuries for families with children aged under 5 years and living in deprived areas. Randomised controlled trial. 47 general practices in Nottingham. 3428 families with children under 5. A standardised safety consultation and provision of free and fitted stair gates, fire guards, smoke alarms, cupboard locks, and window locks. Primary outcome measures were whether a child in the family had at least one injury that required medical attendance and rates of attendance in primary and secondary care and of hospital admission for injury over a two year period. Secondary outcome measures included possession of safety equipment and safety practices. No significant difference was found in the proportion of families in which a child had a medically attended injury (odds ratio 1.14, 95% confidence interval 0.98 to 1.50) or in the rates of attendance in secondary care (incidence rate ratio 1.02, 0.90 to 1.13) or admission to hospital (1.02, 0.70 to 1.48). However, children in the intervention arm had a significantly higher attendance rate for injuries in primary care (1.37, 1.11 to 1.70, P = 0.003). At both one and two years' follow up, families in the intervention arm were significantly more likely to have a range of safety practices, but absolute differences in the percentages were relatively small. The intervention resulted in significant improvements in safety practices for up to two years but did not reduce injuries that necessitated medical attendance. Although equipment was provided and fitted free of charge, the observed changes in safety practices may not have been large enough to affect injury rates.

  3. Controlled release metoprolol for aortic regurgitation: a randomised clinical trial.

    PubMed

    Broch, Kaspar; Urheim, Stig; Lønnebakken, Mai Tone; Stueflotten, Wenche; Massey, Richard; Fosså, Kristian; Hopp, Einar; Aakhus, Svend; Gullestad, Lars

    2016-02-01

    Chronic aortic regurgitation (AR) creates a volume load on the left ventricle, which induces adaptive responses. With time, excessive left ventricular (LV) dilatation may precipitate heart failure. β-adrenergic receptor antagonists (β-blockers) are beneficial in patients with heart failure, but their effect in AR is unclear. This trial was designed to evaluate the effect of controlled release metoprolol on LV remodelling in patients with AR. In this double blind trial, 75 asymptomatic patients aged 44±14 years, 89% males, fulfilling at least two echocardiographic criteria for moderate or severe chronic AR, were randomised to receive metoprolol CR/XL up-titrated to 200 mg/day, or matching placebo. The primary endpoint was LV end diastolic volume, measured by MRI after 6 months of treatment. After 6 months, the difference in the baseline-adjusted LV end diastolic volume between patients allocated to metoprolol and those allocated to placebo was 8 (95% CI -8 to 25) mL (p=0.32). The adjusted LV ejection fraction was 2.7 (95% CI 0.1 to 5.3) percentage points higher in the metoprolol group than in the placebo group (p=0.04). The exercise capacity and peak oxygen consumption did not differ between treatment arms. Serum concentrations of N-terminal pro-B-type natriuretic peptide were 138 (95% CI 71 to 205) pg/mL higher in the metoprolol group (p<0.001). There were no serious adverse events in either treatment arm. Treatment with metoprolol of adults with chronic, moderate to severe AR had no effect on LV volumes. ClinicalTrials.gov Identifier: NCT01157572-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/

  4. Publication status of contemporary oncology randomised controlled trials worldwide.

    PubMed

    Chen, Yu-Pei; Liu, Xu; Lv, Jia-Wei; Li, Wen-Fei; Zhang, Yuan; Guo, Ying; Lin, Ai-Hua; Sun, Ying; Mao, Yan-Ping; Ma, Jun

    2016-10-01

    Little is known about the extent of selective publication in contemporary oncology randomised controlled trials (RCTs) worldwide. This study aimed to evaluate the rates of publication and timely publication (within 24 months) for contemporary oncology RCTs from all over the world. We also investigated the trial characteristics associated with publication and timely publication. We identified all phase III oncology RCTs registered on ClinicalTrials.gov with a primary completion date between January 2008 and December 2012. We searched PubMed and EMBASE to identify publications. The final search date was 31 December 2015. Our primary outcome measure was the time to publication from the primary completion date to the date of primary publication in a peer-reviewed journal. We identified 598 completed oncology RCTs; overall, 398 (66.6%) had been published. For published trials, the median time to publication was 25 months (interquartile range, 16-37 months). Only 192 trials (32.1%) were published within 24 months. Timely publication was independently associated with trials completed late in 2012. Trials conducted in Asia and other regions were less likely to have timely publication, but trials conducted in different locations were all equally likely to be published. Industry- and NIH-funded trials were equally likely to be published timely or at any time after trial completion. Among 391 published trials with clear primary outcomes, there was a trend for timely publication of positive trials compared with negative trials. Despite the ethical obligations and societal expectations of disclosing findings promptly, oncology RCTs performed poorly. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Famciclovir for ophthalmic zoster: a randomised aciclovir controlled study

    PubMed Central

    Tyring, S.; Engst, R.; Corriveau, C.; Robillard, N.; Trottier, S.; Van Slycken, S.; Crann, R.; Locke, L.; Saltzman, R.; Palestine, A.

    2001-01-01

    AIMS—To compare the efficacy and safety of famciclovir with aciclovir for the treatment of ophthalmic zoster.
METHODS—Randomised, double masked, aciclovir controlled, parallel group in 87 centres worldwide including 454 patients with ophthalmic zoster of trigeminal nerve (V1) comprised the intent to treat population. Oral famciclovir 500 mg three times daily or oral aciclovir 800 mg five times daily for 7 days. Assessments included day 0 (screening), days 3 and 7 (during treatment), days 10, 14, 21, 28 and monthly thereafter, up to 6 months (follow up). Proportion of patients who experienced ocular manifestations, severe manifestations and non-severe manifestations; loss of visual acuity was the main outcome measure.
RESULTS—The percentage of patients who experienced one or more ocular manifestations was similar for famciclovir (142/245, 58.0%) and aciclovir (114/196, 58.2%) recipients, with no significant difference between groups (OR 0.99; 95% CI 0.68, 1.45). The percentage of patients who experienced severe and non-severe manifestations was similar between groups, with no significant difference. The prevalence of individual ocular manifestations was comparable between groups. There was no significant difference between groups for visual acuity loss.
CONCLUSION—Famciclovir 500 mg three times daily was well tolerated and demonstrated efficacy similar to aciclovir 800 mg five times daily.

 PMID:11316720

  6. Thermoregulatory effects of swaddling in Mongolia: a randomised controlled study

    PubMed Central

    Tsogt, Bazarragchaa; Manaseki-Holland, Semira; Pollock, Jon; Blair, Peter S; Fleming, Peter

    2016-01-01

    Objective To investigate thermal balance of infants in a Mongolian winter, and compare the effects of traditional swaddling with an infant sleeping-bag in apartments or traditional tents (Gers). Design A substudy within a randomised controlled trial. Setting Community in Ulaanbaatar, Mongolia. Subjects A stratified randomly selected sample of 40 swaddled and 40 non-swaddled infants recruited within 48 h of birth. Intervention Sleeping-bags and baby outfits of total thermal resistance equivalent to that of swaddled babies. Outcome measure Digital recordings of infants’ core, peripheral, environmental and microenvironmental temperatures at 30-s intervals over 24 h at ages 1 month and 3 months. Results In Gers, indoor temperatures varied greatly (<0–>25°C), but remained between 20°C and 22°C, in apartments. Despite this, heavy wrapping, bed sharing and partial head covering, infant core and peripheral temperatures were similar and no infants showed evidence of significant heat or cold stress whether they were swaddled or in sleeping-bags. At 3 months, infants in sleeping-bags showed the ‘mature’ diurnal pattern of a fall in core temperature after sleep onset, accompanied by a rise in peripheral temperature, with a reverse pattern later in the night, just before awakening. This pattern was not related to room temperature, and was absent in the swaddled infants, suggesting that the mature diurnal pattern may develop later in them. Conclusions No evidence of cold stress was found. Swaddling had no identifiable thermal advantages over sleeping-bags during the coldest times, and in centrally heated apartments could contribute to the risk of overheating during the daytime. Trial registration number ISRTN01992617. PMID:26515228

  7. Robust control design techniques for active flutter suppression

    NASA Technical Reports Server (NTRS)

    Ozbay, Hitay; Bachmann, Glen R.

    1994-01-01

    In this paper, an active flutter suppression problem is studied for a thin airfoil in unsteady aerodynamics. The mathematical model of this system is infinite dimensional because of Theodorsen's function which is irrational. Several second order approximations of Theodorsen's function are compared. A finite dimensional model is obtained from such an approximation. We use H infinity control techniques to find a robustly stabilizing controller for active flutter suppression.

  8. Robust trajectory tracking: differential game/cheap control approach

    NASA Astrophysics Data System (ADS)

    Turetsky, Vladimir; Glizer, Valery Y.; Shinar, Josef

    2014-11-01

    A robust trajectory tracking problem is treated in the framework of a zero-sum linear-quadratic differential game of a general type. For the cheap control version of this game, a novel solvability condition is derived. The sufficient condition, guaranteeing that the tracking problem is solved by the optimal strategy of the minimiser in the cheap control game, is established. The boundedness of the time realisations of this strategy is analysed. An illustrative example is presented.

  9. A protocol for a systematic review of non-randomised evaluations of strategies to improve participant recruitment to randomised controlled trials.

    PubMed

    Gardner, Heidi R; Fraser, Cynthia; MacLennan, Graeme; Treweek, Shaun

    2016-08-02

    Randomised controlled trials guard against selection bias and therefore offer the fairest way of evaluating healthcare interventions such as medicinal products, devices and services. Recruitment to trials can be extremely difficult, and poor recruitment can lead to extensions to both time and budget and may result in an underpowered study which does not satisfactorily answer the original research question. In the worst cases, a trial may be abandoned, causing huge waste. The evidence to support the choice of recruitment interventions is currently weak. Non-randomised evaluations of recruitment interventions are currently rejected on grounds of poor methodological quality, but systematic evaluation and assessment of this substantial body of work (using Grading of Recommendations Assessment, Development and Evaluation (GRADE) where possible) may provide useful information to support and inform the recruitment decisions of trialists and the research priorities of methodology researchers. The following databases will be searched for relevant studies: Cochrane Methodology Register, MEDLINE, EMBASE, CINAHL and PsycINFO. Any non-randomised study that includes a comparison of two or more interventions to improve recruitment to randomised controlled trials will be included. We will not apply any restrictions on publication date, language or journal. The primary outcome will be the number of individuals or centres recruited into a randomised controlled trial. The secondary outcome will be cost per recruit. Two reviewers will independently screen abstracts for eligible studies, and then, full texts of potentially relevant records will be reviewed. Disagreements will be resolved through discussion. The methodological quality of studies will be assessed using the Cochrane risk of bias tool for non-randomised studies, and the GRADE system will be used if studies are pooled. This review aims to summarise the evidence on methods used to improve recruitment to randomised controlled

  10. Impedance Control for Robotic Rehabilitation: A Robust Markovian Approach

    PubMed Central

    Jutinico, Andres L.; Jaimes, Jonathan C.; Escalante, Felix M.; Perez-Ibarra, Juan C.; Terra, Marco H.; Siqueira, Adriano A. G.

    2017-01-01

    The human-robot interaction has played an important role in rehabilitation robotics and impedance control has been used in the regulation of interaction forces between the robot actuator and human limbs. Series elastic actuators (SEAs) have been an efficient solution in the design of this kind of robotic application. Standard implementations of impedance control with SEAs require an internal force control loop for guaranteeing the desired impedance output. However, nonlinearities and uncertainties hamper such a guarantee of an accurate force level in this human-robot interaction. This paper addresses the dependence of the impedance control performance on the force control and proposes a control approach that improves the force control robustness. A unified model of the human-robot system that considers the ankle impedance by a second-order dynamics subject to uncertainties in the stiffness, damping, and inertia parameters has been developed. Fixed, resistive, and passive operation modes of the robotics system were defined, where transition probabilities among the modes were modeled through a Markov chain. A robust regulator for Markovian jump linear systems was used in the design of the force control. Experimental results show the approach improves the impedance control performance. For comparison purposes, a standard H∞ force controller based on the fixed operation mode has also been designed. The Markovian control approach outperformed the H∞ control when all operation modes were taken into account. PMID:28883790

  11. A nonlinear robust PI controller for an uncertain system

    NASA Astrophysics Data System (ADS)

    Aguilar-Ibañez, Carlos; Mendoza-Mendoza, Julio A.; Suarez-Castanon, Miguel S.; Davila, Jorge

    2014-05-01

    This paper presents a smooth control strategy for the regulation problem of an uncertain system, which assures uniform ultimate boundedness of the closed-loop system inside of the zero-state neighbourhood. This neighbourhood can be made arbitrarily small. To this end, a class of nonlinear proportional integral controllers or PI controllers was designed. The behaviour of this controller emulates very close a sliding mode controller. To accomplish this behaviour saturation functions were combined with traditional PI controller. The controller did not need a high-gain controller or a sliding mode controller to accomplish robustness against unmodelled persistent perturbations. The obtained closed-solution has a finite time of convergence in a small vicinity. The corresponding stability convergence analysis was done applying the traditional Lyapunov method. Numerical simulations were carried out to assess the effectiveness of the obtained controller.

  12. Random allocation or allocation at random? Patients' perspectives of participation in a randomised controlled trial.

    PubMed

    Featherstone, K; Donovan, J L

    1998-10-31

    To explore trial participants' understandings of randomisation. In this exploratory study, which used qualitative research methods, in-depth, semistructured interviews were carried out with 20 participants from the CLasP randomised controlled trial. Interviews were recorded on audio tape and fully transcribed. Data were analysed by comparing transcripts and describing emergent themes, using a grounded theory approach. The CLasP study comprises three linked multicentre, pragmatic randomised controlled trials evaluating the effectiveness and cost effectiveness of laser therapy, standard surgery, and conservative management for men with lower urinary tract symptoms or urinary retention, or both, related to benign prostatic disease. 20 participants in the CLasP study were interviewed. Sampling was purposeful: men were included from each of the treatment arms, the two major centres, and at different points in the trial. Interviews used a checklist of topics to encourage participants to describe their experiences. Narratives concerning randomisation were compared to identify common themes, retaining the context of the discussion to allow detailed interpretation. Most participants recalled and described aspects of randomisation, such as the involvement of chance, comparison, and concealed allocation. Many found the concept of randomisation difficult, however, and developed alternative lay explanations to make sense of their experiences. Inaccurate patient information and lay interpretations of common trial terms caused confusion. The provision of clear and accurate patient information is important, but this alone will not ensure consistent interpretation of concepts such as randomisation. Patients may need to discuss the purposes of randomisation in order to understand them fully enough to give truly informed consent.

  13. Random allocation or allocation at random? Patients’ perspectives of participation in a randomised controlled trial

    PubMed Central

    Featherstone, Katie; Donovan, Jenny L

    1998-01-01

    Objectives To explore trial participants’ understandings of randomisation. Design In this exploratory study, which used qualitative research methods, in-depth, semistructured interviews were carried out with 20 participants from the CLasP randomised controlled trial. Interviews were recorded on audio tape and fully transcribed. Data were analysed by comparing transcripts and describing emergent themes, using a grounded theory approach. Setting The CLasP study comprises three linked multicentre, pragmatic randomised controlled trials evaluating the effectiveness and cost effectiveness of laser therapy, standard surgery, and conservative management for men with lower urinary tract symptoms or urinary retention, or both, related to benign prostatic disease. Subjects 20 participants in the CLasP study were interviewed. Sampling was purposeful: men were included from each of the treatment arms, the two major centres, and at different points in the trial. Interventions and outcome measures Interviews used a checklist of topics to encourage participants to describe their experiences. Narratives concerning randomisation were compared to identify common themes, retaining the context of the discussion to allow detailed interpretation. Results Most participants recalled and described aspects of randomisation, such as the involvement of chance, comparison, and concealed allocation. Many found the concept of randomisation difficult, however, and developed alternative lay explanations to make sense of their experiences. Inaccurate patient information and lay interpretations of common trial terms caused confusion. Conclusions The provision of clear and accurate patient information is important, but this alone will not ensure consistent interpretation of concepts such as randomisation. Patients may need to discuss the purposes of randomisation in order to understand them fully enough to give truly informed consent. Key messagesMost trial participants were able to recall and

  14. Applicability and generalisability of published results of randomised controlled trials and non-randomised studies evaluating four orthopaedic procedures: methodological systematic review.

    PubMed

    Pibouleau, Leslie; Boutron, Isabelle; Reeves, Barnaby C; Nizard, Rémy; Ravaud, Philippe

    2009-11-17

    To compare the reporting of essential applicability data from randomised controlled trials and non-randomised studies evaluating four new orthopaedic surgical procedures. Medline and the Cochrane central register of controlled trials. All articles of comparative studies assessing total hip or knee arthroplasty carried out by a minimally invasive approach or computer assisted navigation system. Items judged to be essential for interpreting the applicability of findings about such procedures were identified by a survey of a sample of orthopaedic surgeons (77 of 512 completed the survey). Reports were evaluated for data describing these "essential" items and the number of centres and surgeons involved in the trials. When data on the number of centres and surgeons were not reported, the corresponding author of the selected trials was contacted. Results 84 articles were identified (38 randomised controlled trials, 46 non-randomised studies). The median percentage (interquartile range) of essential items reported for non-randomised studies compared with randomised controlled trials was 38% (25-63%) versus 44% (38-45%) for items about patients, 71% (43-86%) versus 71% (57-86%) for items considered essential for all interventions, and 38% (25-50%) versus 50% (25-50%) for items about the context of care. More than 80% of both study types were single centre studies, with one or two participating surgeons. The reporting of data related to the applicability of results was poor in published articles of both non-randomised studies and randomised controlled trials and did not differ by study design. The applicability of results from the trials and studies was similar in terms of number of centres and surgeons involved and the reproducibility of the intervention.

  15. Analysis and design of robust decentralized controllers for nonlinear systems

    SciTech Connect

    Schoenwald, D.A.

    1993-07-01

    Decentralized control strategies for nonlinear systems are achieved via feedback linearization techniques. New results on optimization and parameter robustness of non-linear systems are also developed. In addition, parametric uncertainty in large-scale systems is handled by sensitivity analysis and optimal control methods in a completely decentralized framework. This idea is applied to alleviate uncertainty in friction parameters for the gimbal joints on Space Station Freedom. As an example of decentralized nonlinear control, singular perturbation methods and distributed vibration damping are merged into a control strategy for a two-link flexible manipulator.

  16. 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

  17. Randomised controlled trial of the Lidcombe programme of early stuttering intervention

    PubMed Central

    Jones, Mark; Onslow, Mark; Packman, Ann; Williams, Shelley; Ormond, Tika; Schwarz, Ilsa; Gebski, Val

    2005-01-01

    Objectives To evaluate the efficacy of the Lidcombe programme of early stuttering intervention by comparison to a control group. Design A pragmatic, open plan, parallel group, randomised controlled trial with blinded outcome assessment. Setting Two public speech clinics in New Zealand. Participants Stuttering preschool children who presented to the speech clinics for treatment. Inclusion criteria were age 3-6 years and frequency of stuttering of at least 2% syllables stuttered. Exclusion criteria were onset of stuttering during the six months before recruitment and treatment for stuttering during the previous 12 months. 54 participants were randomised: 29 to the Lidcombe programme arm and 25 to the control arm. 12 of the participants were girls. Intervention Lidcombe programme of early stuttering intervention. Main outcome measures Frequency of stuttering was measured as the proportion of syllables stuttered, from audiotaped recordings of participants' conversational speech outside the clinic. Parents in both arms of the trial collected speech samples in three different speaking situations before randomisation and at three, six, and nine months after randomisation. Results Analysis showed a highly significant difference (P = 0.003) at nine months after randomisation. The mean proportion of syllables stuttered at nine months after randomisation was 1.5% (SD 1.4) for the treatment arm and 3.9% (SD 3.5) for the control arm, giving an effect size of 2.3% of syllables stuttered (95% confidence interval 0.8 to 3.9). This effect size was more than double the minimum clinically worthwhile difference specified in the trial protocol. Conclusions The results provide evidence from a randomised controlled trial to support early intervention for stuttering. The Lidcombe programme is an efficacious treatment for stuttering in children of preschool age. PMID:16096286

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Effects of interpretive front-of-pack nutrition labels on food purchases: protocol for the Starlight randomised controlled trial.

    PubMed

    Volkova, Ekaterina; Neal, Bruce; Rayner, Mike; Swinburn, Boyd; Eyles, Helen; Jiang, Yannan; Michie, Jo; Ni Mhurchu, Cliona

    2014-09-18

    Interpretive front-of-pack nutrition labels are better understood than non-interpretive labels. However, robust evidence on the effects of such labels on consumer food purchases in the real-world is lacking. Our aim is to assess the effects of two interpretive front-of-pack nutrition labels, compared with a non-interpretive label, on the healthiness of consumer food purchases. A five-week (1-week baseline and 4-week intervention) three-arm parallel randomised controlled trial will be conducted using a bespoke smartphone application, which will administer study questionnaires and deliver intervention (Multiple Traffic Light and Health Star Rating) and control (Nutrition Information Panel) labels. To view their allocated nutrition label, participants scan the barcode of packaged food products using their smartphone camera. The assigned label is displayed instantly on the smartphone screen.1500 eligible participants (New Zealand adult smartphone owners who shop in a supermarket at least once a week and are main household shoppers) will be randomised in a 1:1:1 ratio to one of the three nutrition label formats, using computer-generated randomisation sequences. Randomisation will be stratified by ethnicity and interest in healthy eating. Food and beverage purchase data will be collected continuously throughout the study via hard copy till receipts and electronic grocery purchase lists recorded and transmitted using the smartphone application. The primary outcome will be healthiness of food purchases in each trial arm, assessed as mean Food Standards Australia New Zealand nutrient profiling score criterion score for all food and beverages purchased over the intervention period. Secondary outcomes will include saturated fat, sugar, sodium and energy content of food purchases; food expenditure; labelling profile of food purchases (i.e. mean number of Health Star Rating stars and proportion of red, green and amber traffic lights); nutrient profiling score over time and by

  3. 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

  4. 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

  5. A general framework for robust control in fluid mechanics

    NASA Astrophysics Data System (ADS)

    Bewley, Thomas R.; Temam, Roger; Ziane, Mohammed

    2000-04-01

    The application of optimal control theory to complex problems in fluid mechanics has proven to be quite effective when complete state information from high-resolution numerical simulations is available [P. Moin, T.R. Bewley, Appl. Mech. Rev., Part 2 47 (6) (1994) S3-S13; T.R. Bewley, P. Moin, R. Temam, J. Fluid Mech. (1999), submitted for publication]. In this approach, an iterative optimization algorithm based on the repeated computation of an adjoint field is used to optimize the controls for finite-horizon nonlinear flow problems [F. Abergel, R. Temam, Theoret. Comput. Fluid Dyn. 1 (1990) 303-325]. In order to extend this infinite-dimensional optimization approach to control externally disturbed flows in which the controls must be determined based on limited noisy flow measurements alone, it is necessary that the controls computed be insensitive to both state disturbances and measurement noise. For this reason, robust control theory, a generalization of optimal control theory, has been examined as a technique by which effective control algorithms which are insensitive to a broad class of external disturbances may be developed for a wide variety of infinite-dimensional linear and nonlinear problems in fluid mechanics. An aim of the present paper is to put such algorithms into a rigorous mathematical framework, for it cannot be assumed at the outset that a solution to the infinite-dimensional robust control problem even exists. In this paper, conditions on the initial data, the parameters in the cost functional, and the regularity of the problem are established such that existence and uniqueness of the solution to the robust control problem can be proven. Both linear and nonlinear problems are treated, and the 2D and 3D nonlinear cases are treated separately in order to get the best possible estimates. Several generalizations are discussed and an appropriate numerical method is proposed.

  6. Modeling, Robust Control, and Experimental Validation of a Supercavitating Vehicle

    NASA Astrophysics Data System (ADS)

    Escobar Sanabria, David

    This dissertation considers the mathematical modeling, control under uncertainty, and experimental validation of an underwater supercavitating vehicle. By traveling inside a gas cavity, a supercavitating vehicle reduces hydrodynamic drag, increases speed, and minimizes power consumption. The attainable speed and power efficiency make these vehicles attractive for undersea exploration, high-speed transportation, and defense. However, the benefits of traveling inside a cavity come with difficulties in controlling the vehicle dynamics. The main challenge is the nonlinear force that arises when the back-end of the vehicle pierces the cavity. This force, referred to as planing, leads to oscillatory motion and instability. Control technologies that are robust to planing and suited for practical implementation need to be developed. To enable these technologies, a low-order vehicle model that accounts for inaccuracy in the characterization of planing is required. Additionally, an experimental method to evaluate possible pitfalls in the models and controllers is necessary before undersea testing. The major contribution of this dissertation is a unified framework for mathematical modeling, robust control synthesis, and experimental validation of a supercavitating vehicle. First, we introduce affordable experimental methods for mathematical modeling and controller testing under planing and realistic flow conditions. Then, using experimental observations and physical principles, we create a low-order nonlinear model of the longitudinal vehicle motion. This model quantifies the planing uncertainty and is suitable for robust controller synthesis. Next, based on the vehicle model, we develop automated tools for synthesizing controllers that deliver a certificate of performance in the face of nonlinear and uncertain planing forces. We demonstrate theoretically and experimentally that the proposed controllers ensure higher performance when the uncertain planing dynamics are

  7. 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.

  8. Robust sliding mode continuous control of an IM drive

    SciTech Connect

    Jezernik, K.; Hren, A.; Drevensek, D.

    1995-12-31

    A control approach for robust trajectory tracking of IM servodrive based on the variable structure systems (VSS) is described. A new discrete-time control algorithm has been developed by combining VSS and Lyapunov design. It possesses all the good properties of the sliding mode and avoids the unnecessary discontinuity of the control input, thus eliminating chattering which has been considering as serious obstacles for applications of VSS. A unified control approach for current, torque and motion control based on the discrete-time sliding mode for application in indirect vector control of an IM drive is developed. The sliding mode approach can be applied to the control of an Im drive due to the replacement of the hysteresis controller with widely used PWM technique. All the theoretical issues are verified by experiment. The experimental system consists of a transputer and a microcontroller, thus allowing parallel processing.

  9. Testing the activitystat hypothesis: a randomised controlled trial protocol

    PubMed Central

    2012-01-01

    Background The activitystat hypothesis proposes that when physical activity or energy expenditure is increased or decreased in one domain, there will be a compensatory change in another domain to maintain an overall, stable level of physical activity or energy expenditure. To date, there has been no experimental study primarily designed to test the activitystat hypothesis in adults. The aim of this trial is to determine the effect of two different imposed exercise loads on total daily energy expenditure and physical activity levels. Methods This study will be a randomised, multi-arm, parallel controlled trial. Insufficiently active adults (as determined by the Active Australia survey) aged 18–60 years old will be recruited for this study (n=146). Participants must also satisfy the Sports Medicine Australia Pre-Exercise Screening System and must weigh less than 150 kg. Participants will be randomly assigned to one of three groups using a computer-generated allocation sequence. Participants in the Moderate exercise group will receive an additional 150 minutes of moderate to vigorous physical activity per week for six weeks, and those in the Extensive exercise group will receive an additional 300 minutes of moderate to vigorous physical activity per week for six weeks. Exercise targets will be accumulated through both group and individual exercise sessions monitored by heart rate telemetry. Control participants will not be given any instructions regarding lifestyle. The primary outcome measures are activity energy expenditure (doubly labeled water) and physical activity (accelerometry). Secondary measures will include resting metabolic rate via indirect calorimetry, use of time, maximal oxygen consumption and several anthropometric and physiological measures. Outcome measures will be conducted at baseline (zero weeks), mid- and end-intervention (three and six weeks) with three (12 weeks) and six month (24 week) follow-up. All assessors will be blinded to group

  10. Impact of industry collaboration on randomised controlled trials in oncology.

    PubMed

    Linker, Anne; Yang, Annie; Roper, Nitin; Whitaker, Evans; Korenstein, Deborah

    2017-02-01

    Industry funders can simply provide money or collaborate in trial design, analysis or reporting of clinical trials. Our aim was to assess the impact of industry collaboration on trial methodology and results of randomised controlled trials (RCT). We searched PubMed for oncology RCTs published May 2013 to December 2015 in peer-reviewed journals with impact factor > 5 requiring reporting of funder role. Two authors extracted methodologic (primary end-point; blinding of the patient, clinician and outcomes assessor; and analysis) and outcome data. We used descriptive statistics and two-sided Fisher exact tests to compare characteristics of trials with collaboration, with industry funding only, and without industry funding. We included 224 trials. Compared to those without industry funding, trials with collaboration used more placebo control (RR 3·59, 95% CI [1·88-6·83], p < 0001), intention-to-treat analysis (RR 1·32, 95% CI [1·04-1·67], p = 02), and blinding of patients (RR 3·05, 95% CI [1·71-5·44], p < 0001), clinicians (RR 3·36, 95% CI [1·83-6·16], p≤·001) and outcomes assessors (RR 3·03, 95% CI [1·57-5·83], p = 0002). They did not differ in use of overall survival as a primary end-point (RR 1·27 95% CI [0·72-2·24]) and were similarly likely to report positive results (RR 1·11 95% CI [0·85-1·46], p = 0.45). Studies with funding only did not differ from those without funding. Oncology RCTs with industry collaboration were more likely to use some high-quality methods than those without industry funding, with similar rates of positive results. Our findings suggest that collaboration is not associated with trial outcomes and that mandatory disclosure of funder roles may mitigate bias. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. 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.

  12. Robust Concentration and Frequency Control in Oscillatory Homeostats

    PubMed Central

    Thorsen, Kristian; Agafonov, Oleg; Selstø, Christina H.; Jolma, Ingunn W.; Ni, Xiao Y.; Drengstig, Tormod; Ruoff, Peter

    2014-01-01

    Homeostatic and adaptive control mechanisms are essential for keeping organisms structurally and functionally stable. Integral feedback is a control theoretic concept which has long been known to keep a controlled variable robustly (i.e. perturbation-independent) at a given set-point by feeding the integrated error back into the process that generates . The classical concept of homeostasis as robust regulation within narrow limits is often considered as unsatisfactory and even incompatible with many biological systems which show sustained oscillations, such as circadian rhythms and oscillatory calcium signaling. Nevertheless, there are many similarities between the biological processes which participate in oscillatory mechanisms and classical homeostatic (non-oscillatory) mechanisms. We have investigated whether biological oscillators can show robust homeostatic and adaptive behaviors, and this paper is an attempt to extend the homeostatic concept to include oscillatory conditions. Based on our previously published kinetic conditions on how to generate biochemical models with robust homeostasis we found two properties, which appear to be of general interest concerning oscillatory and homeostatic controlled biological systems. The first one is the ability of these oscillators (“oscillatory homeostats”) to keep the average level of a controlled variable at a defined set-point by involving compensatory changes in frequency and/or amplitude. The second property is the ability to keep the period/frequency of the oscillator tuned within a certain well-defined range. In this paper we highlight mechanisms that lead to these two properties. The biological applications of these findings are discussed using three examples, the homeostatic aspects during oscillatory calcium and p53 signaling, and the involvement of circadian rhythms in homeostatic regulation. PMID:25238410

  13. Adaptive robust control of longitudinal and transverse electron beam profiles

    NASA Astrophysics Data System (ADS)

    Rezaeizadeh, Amin; Schilcher, Thomas; Smith, Roy S.

    2016-05-01

    Feedback control of the longitudinal and transverse electron beam profiles are considered to be critical for beam control in accelerators. In the feedback scheme, the longitudinal or transverse beam profile is measured and compared to a desired profile to give an error estimate. The error is then used to act on the appropriate actuators to correct the profile. The role of the transverse feedback is to steer the beam in a particular trajectory, known as the "orbit." The common approach for orbit correction is based on approximately inverting the response matrix, and in the best case, involves regulating or filtering the singular values. In the current contribution, a more systematic and structured way of handling orbit correction is introduced giving robustness against uncertainties in the response matrix. Moreover, the input bounds are treated to avoid violating the limits of the corrector currents. The concept of the robust orbit correction has been successfully tested at the SwissFEL injector test facility. In the SwissFEL machine, a photo-injector laser system extracts electrons from a cathode and a similar robust control method is developed for the longitudinal feedback control of the current profile of the electron bunch. The method manipulates the angles of the crystals in the laser system to produce a desired charge distribution over the electron bunch length. This approach paves the way towards automation of laser pulse stacking.

  14. 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.

  15. Does antenatal pelvic floor muscle training affect the outcome of labour? A randomised controlled trial.

    PubMed

    Agur, Wael; Steggles, Pippin; Waterfield, Malcolm; Freeman, Robert

    2008-01-01

    It is thought that antenatal pelvic floor muscle training (PFMT) might produce a strong pelvic floor resulting in prolonged labour, whilst some believe it produces well-controlled muscles that facilitate rotation of the foetal head and shortens the duration of labour. This secondary analysis (of a previously published randomised controlled trial) assesses the labour and delivery details of 268 primigravidae who were originally randomised at approximately 20 weeks gestation to supervised PFMT or a control group. Between the two groups, there was no difference in the duration of the second stage of labour or in the need for instrumental delivery. PFMT does not appear to facilitate or obstruct labour.

  16. Robust adaptive backstepping control for reentry reusable launch vehicles

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Wu, Zhong; Du, Yijiang

    2016-09-01

    During the reentry process of reusable launch vehicles (RLVs), the large range of flight envelope will not only result in high nonlinearities, strong coupling and fast time-varying characteristics of the attitude dynamics, but also result in great uncertainties in the atmospheric density, aerodynamic coefficients and environmental disturbances, etc. In order to attenuate the effects of these problems on the control performance of the reentry process, a robust adaptive backstepping control (RABC) strategy is proposed for RLV in this paper. This strategy consists of two-loop controllers designed via backstepping method. Both the outer and the inner loop adopt a robust adaptive controller, which can deal with the disturbances and uncertainties by the variable-structure term with the estimation of their bounds. The outer loop can track the desired attitude by the design of virtual control-the desired angular velocity, while the inner one can track the desired angular velocity by the design of control torque. Theoretical analysis indicates that the closed-loop system under the proposed control strategy is globally asymptotically stable. Even if the boundaries of the disturbances and uncertainties are unknown, the attitude can track the desired value accurately. Simulation results of a certain RLV demonstrate the effectiveness of the control strategy.

  17. Frequency domain identification for robust large space structure control design

    NASA Technical Reports Server (NTRS)

    Yam, Y.; Bayard, D. S.; Scheid, R. E.

    1991-01-01

    A methodology is demonstrated for frequency domain identification of large space structures which systematically transforms experimental raw data into a form required for synthesizing H(infinity) controllers using modern robust control design software (e.g., Matlab Toolboxes). A unique feature of this approach is that the additive uncertainty is characterized to a specified statistic confidence rather than with hard bounds. In this study, the difference in robust performance is minimal between the two levels of confidence. In general cases, the present methodology provides a tool for performance/confidence level tradeoff studies. For simplicity, the additive uncertainty on a frequency grid is considered and the interpolation error in between grid points is neglected.

  18. Parametric uncertainty modeling for application to robust control

    NASA Technical Reports Server (NTRS)

    Belcastro, Christine M.; Chang, B.-C.; Fischl, Robert

    1993-01-01

    Viewgraphs and a paper on parametric uncertainty modeling for application to robust control are included. Advanced robust control system analysis and design is based on the availability of an uncertainty description which separates the uncertain system elements from the nominal system. Although this modeling structure is relatively straightforward to obtain for multiple unstructured uncertainties modeled throughout the system, it is difficult to formulate for many problems involving real parameter variations. Furthermore, it is difficult to ensure that the uncertainty model is formulated such that the dimension of the resulting model is minimal. A procedure for obtaining an uncertainty model for real uncertain parameter problems in which the uncertain parameters can be represented in a multilinear form is presented. Furthermore, the procedure is formulated such that the resulting uncertainty model is minimal (or near minimal) relative to a given state space realization of the system. The approach is demonstrated for a multivariable third-order example problem having four uncertain parameters.

  19. Frequency domain identification for robust large space structure control design

    NASA Technical Reports Server (NTRS)

    Yam, Y.; Bayard, D. S.; Scheid, R. E.

    1991-01-01

    A methodology is demonstrated for frequency domain identification of large space structures which systematically transforms experimental raw data into a form required for synthesizing H(infinity) controllers using modern robust control design software (e.g., Matlab Toolboxes). A unique feature of this approach is that the additive uncertainty is characterized to a specified statistic confidence rather than with hard bounds. In this study, the difference in robust performance is minimal between the two levels of confidence. In general cases, the present methodology provides a tool for performance/confidence level tradeoff studies. For simplicity, the additive uncertainty on a frequency grid is considered and the interpolation error in between grid points is neglected.

  20. 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

  1. 'PhysioDirect' telephone assessment and advice services for physiotherapy: protocol for a pragmatic randomised controlled trial

    PubMed Central

    Salisbury, Chris; Foster, Nadine E; Bishop, Annette; Calnan, Michael; Coast, Jo; Hall, Jeanette; Hay, Elaine; Hollinghurst, Sandra; Hopper, Cherida; Grove, Sean; Kaur, Surinder; Montgomery, Alan

    2009-01-01

    acceptability of PhysioDirect to patients and staff, and ways in which the service could be improved. Discussion It is still relatively unusual to evaluate new forms of service delivery using randomised controlled trials. By combining rigorous trial methods with economic analysis of cost-effectiveness and qualitative research this study will provide robust evidence to inform decisions about the widespread introduction of PhysioDirect services. Trial registration Current Controlled Trials ISRCTN55666618 PMID:19650913

  2. Robust control charts in industrial production of olive oil

    NASA Astrophysics Data System (ADS)

    Grilo, Luís M.; Mateus, Dina M. R.; Alves, Ana C.; Grilo, Helena L.

    2014-10-01

    Acidity is one of the most important variables in the quality analysis and characterization of olive oil. During the industrial production we use individuals and moving range charts to monitor this variable, which is not always normal distributed. After a brief exploratory data analysis, where we use the bootstrap method, we construct control charts, before and after a Box-Cox transformation, and compare their robustness and performance.

  3. The Speed of Increasing milk Feeds: a randomised controlled trial.

    PubMed

    Abbott, Jane; Berrington, Janet; Bowler, Ursula; Boyle, Elaine; Dorling, Jon; Embleton, Nicholas; Juszczak, Edmund; Leaf, Alison; Linsell, Louise; Johnson, Samantha; McCormick, Kenny; McGuire, William; Roberts, Tracy; Stenson, Ben

    2017-01-28

    In the UK, 1-2% of infants are born very preterm (<32 weeks of gestation) or have very low birth weight (<1500 g). Very preterm infants are initially unable to be fed nutritional volumes of milk and therefore require intravenous nutrition. Milk feeding strategies influence several long and short term health outcomes including growth, survival, infection (associated with intravenous nutrition) and necrotising enterocolitis (NEC); with both infection and NEC being key predictive factors of long term disability. Currently there is no consistent strategy for feeding preterm infants across the UK. The SIFT trial will test two speeds of increasing milk feeds with the primary aim of determining effects on survival without moderate or severe neurodevelopmental disability at 24 months of age, corrected for prematurity. The trial will also examine many secondary outcomes including infection, NEC, time taken to reach full feeds and growth. Two thousand eight hundred very preterm or very low birth weight infants will be recruited from approximately 30 hospitals across the UK to a randomised controlled trial. Infants with severe congenital anomaly or no realistic chance of survival will be excluded. Infants will be randomly allocated to either a faster (30 ml/kg/day) or slower (18 ml/kg/day) rate of increase in milk feeds. Data will be collected during the neonatal hospital stay on weight, infection rates, episodes of NEC, length of stay and time to reach full milk feeds. Long term health outcomes comprising vision, hearing, motor and cognitive impairment will be assessed at 24 months of age (corrected for prematurity) using a parent report questionnaire. Extensive searches have found no active or proposed studies investigating the rate of increasing milk feeds. The results of this trial will have importance for optimising incremental milk feeding for very preterm and/or very low birth weight infants. No additional resources will be required to implement an optimal

  4. A randomised controlled trial of flexibility in routine antenatal care.

    PubMed

    Jewell, D; Sharp, D; Sanders, J; Peters, T J

    2000-10-01

    To assess changes in satisfaction associated with a flexible approach to antenatal care schedules offered to women at low obstetric risk. Randomised controlled trial. Eleven primary care centres providing midwifery care in Avon. Six hundred and nine women at low risk of obstetric complications presenting for antenatal care. A standard antenatal care schedule ('traditional care') was compared with a schedule based on a minimum number of visits and additional visits with timing agreed between women and midwives ('flexible care'). Women's attitudes to pregnancy and motherhood using a subscale of the Maternal Adjustment and Maternal Attitudes scale, satisfaction with antenatal care, and perception of the speed of recognition of antenatal complications. There was no difference between the two groups in terms of attitudes to pregnancy and motherhood (mean difference on Maternal Adjustment and Maternal Attitudes scale -0.64, 95% CI -1.39 to 0.11, P = 0.068) and no difference in the proportions of women reporting antenatal problems as soon as possible (traditional group 74.5%, flexible group 76.4%, difference -2%, 95% CI -12.1 to 8.2, P = 0.70). Women receiving traditional care reported higher levels of satisfaction for the care provided by community midwives (P < 0.01). Women receiving flexible care were more likely to report having a choice over the number and timing of their antenatal visits (P < 0.001), but were also more likely to report that they would like to have been seen more often (P < 0.01). There was no difference between the groups in rates of obstetric complications. An imposed reduction in antenatal visits has been reported to increase dissatisfaction in other studies. In this study, encouraging women to adopt a flexible approach to antenatal care resulted in a similar finding. Successful implementation of such approaches may depend on more careful selection of women who welcome such an approach, more encouragement to pregnant women to express their own

  5. Randomised, controlled trial of efficacy of midwife-managed care.

    PubMed

    Turnbull, D; Holmes, A; Shields, N; Cheyne, H; Twaddle, S; Gilmour, W H; McGinley, M; Reid, M; Johnstone, I; Geer, I; McIlwaine, G; Lunan, C B

    1996-07-27

    Midwife-managed programmes of care are being widely implemented although there has been little investigation of their efficacy. We have compared midwife-managed care with shared care (ie, care divided among midwives, hospital doctors, and general practitioners) in terms of clinical efficacy and women's satisfaction. We carried out a randomised controlled trial of 1299 pregnant women who had no adverse characteristics at booking (consent rate 81.9%). 648 women were assigned midwife-managed care and 651 shared care. The research hypothesis was that compared with shared care, midwife-managed care would produce fewer interventions, similar (or more favourable) outcomes, similar complications, and greater satisfaction with care. Data were collected by retrospective review of case records and self-report questionnaires. Analysis was by intention to treat. Interventions were similar in the two groups or lower with midwife-managed care. For example, women in the midwife-managed group were less likely than women in shared care to have induction of labour (146 [23.9%] vs 199 [33.3%]; 95% CI for difference 4.4-14.5). Women in the midwife-managed group were more likely to have an intact perineum and less likely to have had an episiotomy (p = 0.02), with no significant difference in perineal tears. Complication rates were similar. Overall, 32.8% of women were permanently transferred from midwife-managed care (28.7% for clinical reasons, 3.7% for non-clinical reasons). Women in both groups reported satisfaction with their care but the midwife-managed group were significantly more satisfied with their antenatal (difference in mean scores 0.48 [95% CI 0.41-0.55]), intrapartum (0.28 [0.18-0.37]), hospital-based postnatal care (0.57 [0.45-0.70]), and home-based postnatal care (0.33 [0.25-0.42]). We conclude that midwife-managed care for healthy women, integrated within existing services, is clinically effective and enhances women's satisfaction with maternity care.

  6. 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

  7. 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.

  8. 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.

  9. Cognitive versus exposure therapy for problem gambling: Randomised controlled trial.

    PubMed

    Smith, David P; Battersby, Malcolm W; Harvey, Peter W; Pols, Rene G; Ladouceur, Robert

    2015-06-01

    Problem gambling-specific cognitive therapy (CT) and behavioural (exposure-based) therapy (ET) are two core cognitive-behavioural techniques to treating the disorder, but no studies have directly compared them using a randomised trial. To evaluate differential efficacy of CT and ET for adult problem gamblers at a South Australian gambling therapy service. Two-group randomised, parallel design. Primary outcome was rated by participants using the Victorian Gambling Screen (VGS) at baseline, treatment-end, 1, 3, and 6 month follow-up. Of eighty-seven participants who were randomised and started intervention (CT = 44; ET = 43), 51 (59%) completed intervention (CT = 30; ET = 21). Both groups experienced comparable reductions (improvement) in VGS scores at 12 weeks (mean difference -0.18, 95% CI: -4.48-4.11) and 6 month follow-up (mean difference 1.47, 95% CI: -4.46-7.39). Cognitive and exposure therapies are both viable and effective treatments for problem gambling. Large-scale trials are needed to compare them individually and combined to enhance retention rates and reduce drop-out. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. 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.

  11. Pupil Control Behavior, Classroom Robustness, and Self-Control: Public and Military Secondary Schools.

    ERIC Educational Resources Information Center

    Sartori, Mary Ann; Bauske, Terri; Lunenburg, Fred C.

    2000-01-01

    Investigated students' perceptions of teachers pupil-control behavior, classroom robustness, and student self-control, highlighting possible differences between public and military secondary schools. Humanistic approaches had more positive, interrelated effects among these variables. Military (custodial) classrooms were perceived as less robust,…

  12. Pupil Control Behavior, Classroom Robustness, and Self-Control: Public and Military Secondary Schools.

    ERIC Educational Resources Information Center

    Sartori, Mary Ann; Bauske, Terri; Lunenburg, Fred C.

    2000-01-01

    Investigated students' perceptions of teachers pupil-control behavior, classroom robustness, and student self-control, highlighting possible differences between public and military secondary schools. Humanistic approaches had more positive, interrelated effects among these variables. Military (custodial) classrooms were perceived as less robust,…

  13. 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.

  14. 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.

  15. 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.

  16. Robust spacecraft attitude tracking control using hybrid actuators with uncertainties

    NASA Astrophysics Data System (ADS)

    Cao, Xibin; Wu, Baolin

    2017-07-01

    The problem of spacecraft attitude tracking using hybrid actuators with uncertainties is addressed in this paper. A hybrid actuators configuration that combines reaction wheels for fine pointing and single gimbal control moment gyros for rapid maneuvering is employed for agile spacecraft. A robust control algorithm for the spacecraft attitude tracking problem when the torque axis direction and/or input scaling of the actuators are uncertain is developed. Furthermore, a torque allocation method is proposed for the hybrid actuator configuration to allow a smooth switch between single gimbal control moment gyros and reaction wheels. With this method, single gimbal control moment gyros are used for the phase of rapid maneuvering, while reaction wheels are used for the phase of fine pointing. Simulation results demonstrate the effectiveness of the proposed control scheme.

  17. Lyapunov function gradient generated robust control in the absence of the nominal stabilizing control

    NASA Technical Reports Server (NTRS)

    Blackwell, C. C.

    1987-01-01

    A relevant facet of the application of Lyapunov gradient-generated robust control to unstable linear autonomous plants is explored. It is demonstrated that if the plant, the output, and the nominal stabilizing control satisfy certain conditions, then the robust component alone stabilizes the nominal plant. An example characterized by two zero eigenvalues and two negative real value poles is presented. These results assure that the robust component will fulfill the role of nominal stabilization successfully so long as the possible magnitude of the robust component can overcome the contribution of the instability to positiveness of the Lyapunov rate.

  18. Hipocrates: a robust system for the control of neuromuscular blockade.

    PubMed

    Mendonça, Teresa; Magalhães, Hugo; Lago, Pedro; Esteves, Simão

    2004-08-01

    Development of an automatic system (software package Hipocrates) for the control of neuromuscular blockade by continuous infusion of the non-depolarising types of muscle relaxant drugs presently used in anaesthesia, namely atracurium, cisatracurium, vecuronium and rocuronium. Hipocrates incorporates control strategies based upon classical, adaptive and robust control, as well as a wide range of noise reduction techniques and on-line adaptation to patient-specific characteristics. Therefore, the system provides strong robustness to inter- and intra-individual variability of the patients responses or unexpected circumstances and adaptation to the individual requirements. The control system is easy to set up and to use in a clinical environment. It consists of a portable PC computer, a Datex AS/3 NMT sensor and a B/Braun compact perfusion pump. In the simulation mode the software package incorporates sophisticated generation of pharmacokinetic/pharmacodynamic models driven by simulated drug administration regimes (bolus, continuous infusion and a combination of both). Hipocrates is an advanced standalone application for the control of neuromuscular blockade with a friendly graphic interface. It has been extensively validated, and it can be used on patients undergoing surgery as well as for simulation studies. Therefore Hipocrates also provides an excellent environment for education and training purposes.

  19. A robust decentralized load frequency controller for interconnected power systems.

    PubMed

    Dong, Lili; Zhang, Yao; Gao, Zhiqiang

    2012-05-01

    A novel design of a robust decentralized load frequency control (LFC) algorithm is proposed for an inter-connected three-area power system, for the purpose of regulating area control error (ACE) in the presence of system uncertainties and external disturbances. The design is based on the concept of active disturbance rejection control (ADRC). Estimating and mitigating the total effect of various uncertainties in real time, ADRC is particularly effective against a wide range of parameter variations, model uncertainties, and large disturbances. Furthermore, with only two tuning parameters, the controller provides a simple and easy-to-use solution to complex engineering problems in practice. Here, an ADRC-based LFC solution is developed for systems with turbines of various types, such as non-reheat, reheat, and hydraulic. The simulation results verified the effectiveness of the ADRC, in comparison with an existing PI-type controller tuned via genetic algorithm linear matrix inequalities (GALMIs). The comparison results show the superiority of the proposed solution. Moreover, the stability and robustness of the closed-loop system is studied using frequency-domain analysis.

  20. A randomised controlled trial of a lifestyle behavioural intervention for patients with low back pain, who are overweight or obese: study protocol.

    PubMed

    Williams, Amanda; Wiggers, John; O'Brien, Kate M; Wolfenden, Luke; Yoong, Serene; Campbell, Elizabeth; Robson, Emma; McAuley, James; Haskins, Robin; Kamper, Steven J; Williams, Christopher M

    2016-02-11

    Low back pain is a highly prevalent condition with a significant global burden. Management of lifestyle factors such as overweight and obesity may improve low back pain patient outcomes. Currently there are no randomised controlled trials that have been conducted to assess the effectiveness of lifestyle behavioural interventions in managing low back pain. The aim of this trial is to determine if a telephone-based lifestyle behavioural intervention is effective in reducing pain intensity in overweight or obese patients with low back pain, compared to usual care. A randomised controlled trial will be conducted with patients waiting for an outpatient consultation with an orthopaedic surgeon at a public tertiary referral hospital within New South Wales, Australia for chronic low back pain. Patients will be randomly allocated in a 1:1 ratio to receive a lifestyle behavioural intervention (intervention group) or continue with usual care (control group). After baseline data collection, patients in the intervention group will receive a clinical consultation followed by a 6-month telephone-based lifestyle behavioural intervention (10 individually tailored sessions over a 6-month period) and patients in the control group will continue with usual care. Participants will be followed for 26 weeks and asked to undertake three self-reported questionnaires at baseline (pre-randomisation), week 6 and 26 post randomisation to collect primary and secondary outcome data. The study requires a sample of 80 participants per group to detect a 1.5 point difference in pain intensity (primary outcome) 26 weeks post randomisation. The primary outcome, pain intensity, will be measured using a 0-10 numerical rating scale. The study will provide robust evidence regarding the effectiveness of a lifestyle behavioural intervention in reducing pain intensity in overweight or obese patients with low back pain and inform management of these patients. Australian New Zealand Clinical Trials Registry

  1. Robust lateral pulse jet control of an atmospheric rocket

    NASA Astrophysics Data System (ADS)

    Burchett, Bradley Thomas

    Uncontrolled direct fire rockets exhibit high impact point dispersion, even at relatively short range, and as such have been employed as area weapons on the battlefield. In order to reduce the dispersion of a direct fire rocket, feedback control is employed to fire short-duration solid rocket pulses mounted near the nose of the projectile and acting perpendicular to the projectile axis of symmetry. The feedback law is developed by first determining a piece wise linear model of the projectile swerving motion, subsequently using this linear model to predict the projectile impact point both with and without control, and using the results to command pulses at appropriate times to drive the impact point closer to the specified target. Candidate optimal control laws are formed using rules based on decision grids, and a global control strategy search algorithm. The global search control law proves to be prohibitively computationally expensive for on-line implementation. The performance of the baseline control law is found to be comparable to the rule based and global search optimal control laws. The control gains of the baseline control law are optimized in the presence of parametric plant uncertainty using a Monte Carlo simulation. Performance of the system in the presence of parametric plant uncertainty using the optimized gains is deemed comparable to performance of the baseline controller with no plant uncertainty. The level of uncertainty of several plant parameters is varied in order to compare robustness of the controller when optimized with uncertainty viz. without uncertainty.

  2. 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.

  3. Robust H∞ state-feedback control for linear systems.

    PubMed

    Chen, Hao; Zhang, Zhenzhen; Wang, Huazhang

    2017-04-01

    This paper investigates the problem of robust H∞ control for linear systems. First, the state-feedback closed-loop control algorithm is designed. Second, by employing the geometric progression theory, a modified augmented Lyapunov-Krasovskii functional (LKF) with the geometric integral interval is established. Then, parameter uncertainties and the derivative of the delay are flexibly described by introducing the convex combination skill. This technique can eliminate the unnecessary enlargement of the LKF derivative estimation, which gives less conservatism. In addition, the designed controller can ensure that the linear systems are globally asymptotically stable with a guaranteed H∞ performance in the presence of a disturbance input and parameter uncertainties. A liquid monopropellant rocket motor with a pressure feeding system is evaluated in a simulation example. It shows that this proposed state-feedback control approach achieves the expected results for linear systems in the sense of the prescribed H∞ performance.

  4. Robust adaptive backstepping control for piezoelectric nano-manipulating systems

    NASA Astrophysics Data System (ADS)

    Zhang, Yangming; Yan, Peng; Zhang, Zhen

    2017-01-01

    In this paper we present a systematic modeling and control approach for nano-manipulations of a two-dimensional PZT (piezoelectric transducer) actuated servo stage. The major control challenges associated with piezoelectric nano-manipulators typically include the nonlinear dynamics of hysteresis, model uncertainties, and various disturbances. The adverse effects of these complications will result in significant performance loss, unless effectively eliminated. The primary goal of the paper is on the ultra high precision control of such systems by handling various model uncertainties and disturbances simultaneously. To this end, a novel robust adaptive backstepping-like control approach is developed such that parametric uncertainties can be estimated adaptively while the nonlinear dynamics and external disturbances are treated as bounded disturbances for robust elimination. Meanwhile, the L2-gain of the closed-loop system is considered, and an H∞ optimization problem is formulated to improve the tracking accuracy. Numerical simulations and real time experiments are finally conducted, which significantly outperform conventional PID methods and achieve around 1% tracking error for circular contouring tasks.

  5. Robust controller design for fuzzy parametric uncertain systems: an optimal control approach.

    PubMed

    Patre, Balasaheb M; Bhiwani, R J

    2013-03-01

    A new approach of designing a robust controller for fuzzy parametric uncertain systems is proposed. A linear time invariant (LTI) system with fuzzy coefficients is called as fuzzy parametric uncertain system (FPUS). The proposed method envisages conversion of the FPUS into an uncertain (interval) state space controllable canonical form system in terms of its alpha cut. Further, the problem of designing a robust controller is translated into an optimal control problem minimizing a cost function. For matched uncertainty, it is shown that the optimal control problem is a linear quadratic regulator (LQR) problem, which can be solved to obtain a robust controller for FPUS. The numerical examples and simulation results show the effectiveness of the proposed method in terms of robustness of the controller. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

  6. 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.

  7. Gabapentin for the Management of Chronic Pelvic Pain in Women (GaPP1): A Pilot Randomised Controlled Trial

    PubMed Central

    Lewis, Steff C.; Bhattacharya, Siladitya; Wu, Olivia; Vincent, Katy; Jack, Stuart A.; Critchley, Hilary O. D.; Porter, Maureen A.; Cranley, Denise; Wilson, John A.; Horne, Andrew W.

    2016-01-01

    Chronic pelvic pain (CPP) affects 2.1–24% of women. Frequently, no underlying pathology is identified, and the pain is difficult to manage. Gabapentin is prescribed for CPP despite no robust evidence of efficacy. We performed a pilot trial in two UK centres to inform the planning of a future multicentre RCT to evaluate gabapentin in CPP management. Our primary objective was to determine levels of participant recruitment and retention. Secondary objectives included estimating potential effectiveness, acceptability to participants of trial methodology, and cost-effectiveness of gabapentin. Women with CPP and no obvious pelvic pathology were assigned to an increasing regimen of gabapentin (300-2700mg daily) or placebo. We calculated the proportion of eligible women randomised, and of randomised participants who were followed up to six months. The analyses by treatment group were by intention-to-treat. Interviews were conducted to evaluate women’s experiences of the trial. A probabilistic decision analytical model was used to estimate cost-effectiveness. Between September 2012–2013, 47 women (34% of those eligible) were randomised (22 to gabapentin, 25 to placebo), and 25 (53%) completed six-month follow-up. Participants on gabapentin had less pain (BPI difference 1.72 points, 95% CI:0.07–3.36), and an improvement in mood (HADS difference 4.35 points, 95% CI:1.97–6.73) at six months than those allocated placebo. The majority of participants described their trial experience favorably. At the UK threshold for willingness-to-pay, the probabilities of gabapentin or no treatment being cost-effective are similar. A pilot trial assessing gabapentin for CPP was feasible, but uncertainty remains, highlighting the need for a large definitive trial. Trial registration Controlled-Trials.com ISRCTN45178534 PMID:27070434

  8. A robust adaptive load frequency control for micro-grids.

    PubMed

    Khooban, Mohammad-Hassan; Niknam, Taher; Blaabjerg, Frede; Davari, Pooya; Dragicevic, Tomislav

    2016-11-01

    The goal of this study is to introduce a novel robust load frequency control (LFC) strategy for micro-grid(s) (MG(s)) in islanded mode operation. Admittedly, power generators in MG(s) cannot supply steady electric power output and sometimes cause unbalance between supply and demand. Battery energy storage system (BESS) is one of the effective solutions to these problems. Due to the high cost of the BESS, a new idea of Vehicle-to-Grid (V2G) is that a battery of Electric-Vehicle (EV) can be applied as a tantamount large-scale BESS in MG(s). As a result, a new robust control strategy for an islanded micro-grid (MG) is introduced that can consider electric vehicles׳ (EV(s)) effect. Moreover, in this paper, a new combination of the General Type II Fuzzy Logic Sets (GT2FLS) and the Modified Harmony Search Algorithm (MHSA) technique is applied for adaptive tuning of proportional-integral (PI) controller. Implementing General Type II Fuzzy Systems is computationally expensive. However, using a recently introduced α-plane representation, GT2FLS can be seen as a composition of several Interval Type II Fuzzy Logic Systems (IT2FLS) with a corresponding level of α for each. Real-data from an offshore wind farm in Sweden and solar radiation data in Aberdeen (United Kingdom) was used in order to examine the performance of the proposed novel controller. A comparison is made between the achieved results of Optimal Fuzzy-PI (OFPI) controller and those of Optimal Interval Type II Fuzzy-PI (IT2FPI) controller, which are of most recent advances in the area at hand. The Simulation results prove the successfulness and effectiveness of the proposed controller.

  9. Robust observer-based adaptive fuzzy sliding mode controller

    NASA Astrophysics Data System (ADS)

    Oveisi, Atta; Nestorović, Tamara

    2016-08-01

    In this paper, a new observer-based adaptive fuzzy integral sliding mode controller is proposed based on the Lyapunov stability theorem. The plant is subjected to a square-integrable disturbance and is assumed to have mismatch uncertainties both in state- and input-matrices. Based on the classical sliding mode controller, the equivalent control effort is obtained to satisfy the sufficient requirement of sliding mode controller and then the control law is modified to guarantee the reachability of the system trajectory to the sliding manifold. In order to relax the norm-bounded constrains on the control law and solve the chattering problem of sliding mode controller, a fuzzy logic inference mechanism is combined with the controller. An adaptive law is then introduced to tune the parameters of the fuzzy system on-line. Finally, for evaluating the controller and the robust performance of the closed-loop system, the proposed regulator is implemented on a real-time mechanical vibrating system.

  10. 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.

  11. 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 Vs postal data collection and the most appropriate methods of measuring primary outcomes (return to work, retention) to determine the sample size for a

  12. 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.

  13. 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.

  14. Robust control of novel pendulum-type vibration isolation system

    NASA Astrophysics Data System (ADS)

    Tsai, Meng-Shiun; Sun, Yann-Shuoh; Liu, Chun-Hsieh

    2011-08-01

    A novel pendulum-type vibration isolation system is proposed consisting of three active cables with embedded piezoelectric actuators and a passive elastomer layer. The dynamic response of the isolation module in the vertical and horizontal directions is modeled using the Lagrangian approach. The validity of the dynamic model is confirmed by comparing the simulation results for the frequency response in the vertical and horizontal directions with the experimental results. An approximate model is proposed to take into account system uncertainties such as payload changes and hysteresis effects. A robust quantitative feedback theory (QFT)-based active controller is then designed to ensure that the active control can achieve a high level of disturbance rejection in the low-frequency range even under variable loading conditions. It is shown that the controller achieves average disturbance rejection of -14 dB in the 2-60 Hz bandwidth range and -35 dB at the resonance frequency. The experimental results confirm that the proposed system achieves a robust vibration isolation performance under the payload in the range of 40-60 kg.

  15. Telemonitoring and self-management in the control of hypertension (TASMINH2): a randomised controlled trial.

    PubMed

    McManus, Richard J; Mant, Jonathan; Bray, Emma P; Holder, Roger; Jones, Miren I; Greenfield, Sheila; Kaambwa, Billingsley; Banting, Miriam; Bryan, Stirling; Little, Paul; Williams, Bryan; Hobbs, F D Richard

    2010-07-17

    Control of blood pressure is a key component of cardiovascular disease prevention, but is difficult to achieve and until recently has been the sole preserve of health professionals. This study assessed whether self-management by people with poorly controlled hypertension resulted in better blood pressure control compared with usual care. This randomised controlled trial was undertaken in 24 general practices in the UK. Patients aged 35-85 years were eligible for enrolment if they had blood pressure more than 140/90 mm Hg despite antihypertensive treatment and were willing to self-manage their hypertension. Participants were randomly assigned in a 1:1 ratio to self-management, consisting of self-monitoring of blood pressure and self-titration of antihypertensive drugs, combined with telemonitoring of home blood pressure measurements or to usual care. Randomisation was done by use of a central web-based system and was stratified by general practice with minimisation for sex, baseline systolic blood pressure, and presence or absence of diabetes or chronic kidney disease. Neither participants nor investigators were masked to group assignment. The primary endpoint was change in mean systolic blood pressure between baseline and each follow-up point (6 months and 12 months). All randomised patients who attended follow-up visits at 6 months and 12 months and had complete data for the primary outcome were included in the analysis, without imputation for missing data. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN17585681. 527 participants were randomly assigned to self-management (n=263) or control (n=264), of whom 480 (91%; self-management, n=234; control, n=246) were included in the primary analysis. Mean systolic blood pressure decreased by 12.9 mm Hg (95% CI 10.4-15.5) from baseline to 6 months in the self-management group and by 9.2 mm Hg (6.7-11.8) in the control group (difference between groups 3.7 mm Hg, 0.8-6.6; p=0

  16. Robust Inversion and Data Compression in Control Allocation

    NASA Technical Reports Server (NTRS)

    Hodel, A. Scottedward

    2000-01-01

    We present an off-line computational method for control allocation design. The control allocation function delta = F(z)tau = delta (sub 0) (z) mapping commanded body-frame torques to actuator commands is implicitly specified by trim condition delta (sub 0) (z) and by a robust pseudo-inverse problem double vertical line I - G(z) F(z) double vertical line less than epsilon (z) where G(z) is a system Jacobian evaluated at operating point z, z circumflex is an estimate of z, and epsilon (z) less than 1 is a specified error tolerance. The allocation function F(z) = sigma (sub i) psi (z) F (sub i) is computed using a heuristic technique for selecting wavelet basis functions psi and a constrained least-squares criterion for selecting the allocation matrices F (sub i). The method is applied to entry trajectory control allocation for a reusable launch vehicle (X-33).

  17. 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…

  18. 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.…

  19. 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…

  20. 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…

  1. 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…

  2. 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…

  3. 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…

  4. 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…

  5. 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…

  6. A New Social Communication Intervention for Children with Autism: Pilot Randomised Controlled Treatment Study Suggesting Effectiveness

    ERIC Educational Resources Information Center

    Aldred, Catherine; Green, Jonathan; Adams, Catherine

    2004-01-01

    Background: Psychosocial treatments are the mainstay of management of autism in the UK but there is a notable lack of a systematic evidence base for their effectiveness. Randomised controlled trial (RCT) studies in this area have been rare but are essential because of the developmental heterogeneity of the disorder. We aimed to test a new…

  7. 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…

  8. 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.…

  9. 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…

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

    PubMed

    van der Hoeven, Erik J R J; Schonewille, Wouter J; Vos, Jan Albert; Algra, Ale; Audebert, Heinrich J; Berge, Eivind; Ciccone, Alfonso; Mazighi, Mikael; Michel, Patrik; Muir, Keith W; Obach, Víctor; Puetz, Volker; Wijman, Cristanne A C; Zini, Andrea; Kappelle, Jaap L

    2013-07-08

    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. 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. 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.gov: NCT01717755).

  11. 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

  12. Robust Decentralized Nonlinear Control for a Twin Rotor MIMO System

    PubMed Central

    Belmonte, Lidia María; Morales, Rafael; Fernández-Caballero, Antonio; Somolinos, José Andrés

    2016-01-01

    This article presents the design of a novel decentralized nonlinear multivariate control scheme for an underactuated, nonlinear and multivariate laboratory helicopter denominated the twin rotor MIMO system (TRMS). The TRMS is characterized by a coupling effect between rotor dynamics and the body of the model, which is due to the action-reaction principle originated in the acceleration and deceleration of the motor-propeller groups. The proposed controller is composed of two nested loops that are utilized to achieve stabilization and precise trajectory tracking tasks for the controlled position of the generalized coordinates of the TRMS. The nonlinear internal loop is used to control the electrical dynamics of the platform, and the nonlinear external loop allows the platform to be perfectly stabilized and positioned in space. Finally, we illustrate the theoretical control developments with a set of experiments in order to verify the effectiveness of the proposed nonlinear decentralized feedback controller, in which a comparative study with other controllers is performed, illustrating the excellent performance of the proposed robust decentralized control scheme in both stabilization and trajectory tracking tasks. PMID:27472338

  13. 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.

  14. Robust Decentralized Nonlinear Control for a Twin Rotor MIMO System.

    PubMed

    Belmonte, Lidia María; Morales, Rafael; Fernández-Caballero, Antonio; Somolinos, José Andrés

    2016-07-27

    This article presents the design of a novel decentralized nonlinear multivariate control scheme for an underactuated, nonlinear and multivariate laboratory helicopter denominated the twin rotor MIMO system (TRMS). The TRMS is characterized by a coupling effect between rotor dynamics and the body of the model, which is due to the action-reaction principle originated in the acceleration and deceleration of the motor-propeller groups. The proposed controller is composed of two nested loops that are utilized to achieve stabilization and precise trajectory tracking tasks for the controlled position of the generalized coordinates of the TRMS. The nonlinear internal loop is used to control the electrical dynamics of the platform, and the nonlinear external loop allows the platform to be perfectly stabilized and positioned in space. Finally, we illustrate the theoretical control developments with a set of experiments in order to verify the effectiveness of the proposed nonlinear decentralized feedback controller, in which a comparative study with other controllers is performed, illustrating the excellent performance of the proposed robust decentralized control scheme in both stabilization and trajectory tracking tasks.

  15. Active structural vibration control: Robust to temperature variations

    NASA Astrophysics Data System (ADS)

    Gupta, Vivek; Sharma, Manu; Thakur, Nagesh

    2012-11-01

    d-form augmented piezoelectric constitutive equations which take into account temperature dependence of piezoelectric strain coefficient (d31) and permittivity (∈33), are converted into e-form. Using e-form constitutive equations, a finite element model of a smart two dimensional plate instrumented with piezoelectric patches is derived. Equations of motion are derived using Hamilton's variational principle. Coupled equations of motion are uncoupled using modal analysis. Modal state vectors are estimated using the Kalman observer. The first mode of smart cantilevered plate is actively controlled using negative first modal velocity feedback at various temperatures. Total control effort required to do so is calculated using the electro-mechanical impedance method. The temperature dependence of sensor voltage, control voltage, control effort and Kalman observer equations is shown analytically. Simulation results are presented using MATLAB. Variations in (i) peak sensor voltage, (ii) actual and estimated first modal velocities, (iii) peak control voltage, (iv) total control effort and (v) settling time with respect to temperature are presented. Active vibration control performance is not maintained at temperature away from reference temperature when the temperature dependence of piezoelectric stress coefficient ‘e31' and permittivity ‘∈33' is not included in piezoelectric constitutive equations. Active control of vibrations becomes robust to temperature variations when the temperature dependence of ‘e31' and ‘∈33' is included in piezoelectric constitutive equations.

  16. Non-compliance with randomised allocation and missing outcome data in randomised controlled trials evaluating surgical interventions: a systematic review.

    PubMed

    Adewuyi, Temitope E; MacLennan, Graeme; Cook, Jonathan A

    2015-09-02

    Randomised controlled trials are widely acknowledged as the gold standard in medical research although their validity can be undermined by non-compliance with the randomly allocated treatment and missing data. Due to the nature of the intervention, surgical trials face particular threat to compliance and data collection. For example, ineligibility for the intervention may only become apparent once the operation has commenced. It is unclear how such cases are reported and handled. The objective was to assess non-compliance and missing data in reports of trials of surgical interventions. Searches for reports of trials involving at least one surgical procedure and published in 2010 were carried out in the Medical Literature Analysis and Retrieval System Online (MEDLINE(®)). Data on missing data, non-compliance and methods of handling missing data were extracted from full texts. Descriptive data analyses were carried out on the data. Forty-five (55%) studies reported non-compliance with treatment allocation and 52 (63%) reported primary outcome missing data. The median levels of non-compliance and missing data were 2% [IQR (0, 5), range (0-29)] and 6% [IQR (0, 15), range (0-57)], respectively. Fifty-two (63%) studies analysed as randomised, 17 (21%) analysed per protocol and 3 (4%) analysed as treated. Complete case analysis was the most common method used to deal with missing data, 35/52 (67%). The reporting of non-compliance to allocation and the handling of missing data were typically suboptimal. There is still room for improvement on the use of the CONSORT statement particularly in accounting for study participants. Transparency in reporting would facilitate evidence synthesis.

  17. Genetic and Environmental Control of Neurodevelopmental Robustness in Drosophila

    PubMed Central

    Mellert, David J.; Williamson, W. Ryan; Shirangi, Troy R.; Card, Gwyneth M.; Truman, James W.

    2016-01-01

    Interindividual differences in neuronal wiring may contribute to behavioral individuality and affect susceptibility to neurological disorders. To investigate the causes and potential consequences of wiring variation in Drosophila melanogaster, we focused on a hemilineage of ventral nerve cord interneurons that exhibits morphological variability. We find that late-born subclasses of the 12A hemilineage are highly sensitive to genetic and environmental variation. Neurons in the second thoracic segment are particularly variable with regard to two developmental decisions, whereas its segmental homologs are more robust. This variability “hotspot” depends on Ultrabithorax expression in the 12A neurons, indicating variability is cell-intrinsic and under genetic control. 12A development is more variable and sensitive to temperature in long-established laboratory strains than in strains recently derived from the wild. Strains with a high frequency of one of the 12A variants also showed a high frequency of animals with delayed spontaneous flight initiation, whereas other wing-related behaviors did not show such a correlation and were thus not overtly affected by 12A variation. These results show that neurodevelopmental robustness is variable and under genetic control in Drosophila and suggest that the fly may serve as a model for identifying conserved gene pathways that stabilize wiring in stressful developmental environments. Moreover, some neuronal lineages are variation hotspots and thus may be more amenable to evolutionary change. PMID:27223118

  18. Genetic and Environmental Control of Neurodevelopmental Robustness in Drosophila.

    PubMed

    Mellert, David J; Williamson, W Ryan; Shirangi, Troy R; Card, Gwyneth M; Truman, James W

    2016-01-01

    Interindividual differences in neuronal wiring may contribute to behavioral individuality and affect susceptibility to neurological disorders. To investigate the causes and potential consequences of wiring variation in Drosophila melanogaster, we focused on a hemilineage of ventral nerve cord interneurons that exhibits morphological variability. We find that late-born subclasses of the 12A hemilineage are highly sensitive to genetic and environmental variation. Neurons in the second thoracic segment are particularly variable with regard to two developmental decisions, whereas its segmental homologs are more robust. This variability "hotspot" depends on Ultrabithorax expression in the 12A neurons, indicating variability is cell-intrinsic and under genetic control. 12A development is more variable and sensitive to temperature in long-established laboratory strains than in strains recently derived from the wild. Strains with a high frequency of one of the 12A variants also showed a high frequency of animals with delayed spontaneous flight initiation, whereas other wing-related behaviors did not show such a correlation and were thus not overtly affected by 12A variation. These results show that neurodevelopmental robustness is variable and under genetic control in Drosophila and suggest that the fly may serve as a model for identifying conserved gene pathways that stabilize wiring in stressful developmental environments. Moreover, some neuronal lineages are variation hotspots and thus may be more amenable to evolutionary change.

  19. 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

  20. Robust isothermal electric control of exchange bias at room temperature

    NASA Astrophysics Data System (ADS)

    Binek, Christian

    2011-03-01

    Voltage-controlled spintronics is of particular importance to continue progress in information technology through reduced power consumption, enhanced processing speed, integration density, and functionality in comparison with present day CMOS electronics. Almost all existing and prototypical solid-state spintronic devices rely on tailored interface magnetism, enabling spin-selective transmission or scattering of electrons. Controlling magnetism at thin-film interfaces, preferably by purely electrical means, is a key challenge to better spintronics. Currently, most attempts to electrically control magnetism focus on potentially large magnetoelectric effects of multiferroics. We report on our interest in magnetoelectric Cr 2 O3 (chromia). Robust isothermal electric control of exchange bias is achieved at room temperature in perpendicular anisotropic Cr 2 O3 (0001)/CoPd exchange bias heterostructures. This discovery promises significant implications for potential spintronics. From the perspective of basic science, our finding serves as macroscopic evidence for roughness-insensitive and electrically controllable equilibrium boundary magnetization in magnetoelectric antiferromagnets. The latter evolves at chromia (0001) surfaces and interfaces when chromia is in one of its two degenerate antiferromagnetic single domain states selected via magnetoelectric annealing. Theoretical insight into the boundary magnetization and its role in electrically controlled exchange bias is gained from first-principles calculations and general symmetry arguments. Measurements of spin-resolved ultraviolet photoemission, magnetometry at Cr 2 O3 (0001) surfaces, and detailed investigations of the unique exchange bias properties of Cr 2 O3 (0001)/CoPd including its electric controllability provide macroscopically averaged information about the boundary magnetization of chromia. Laterally resolved X-ray PEEM and temperature dependent MFM reveal detailed microscopic information of the chromia

  1. Robust and fault tolerant control of modular and reconfigurable robots

    NASA Astrophysics Data System (ADS)

    Abdul, Sajan

    Modular and reconfigurable robot has been one of the main areas of robotics research in recent years due to its wide range of applications, especially in aerospace sector. Dynamic control of manipulators can be performed using joint torque sensing with little information of the link dynamics. From the modular robot perspective, this advantage offered by the torque sensor can be taken to enhance the modularity of the control system. Known modular robots though boast novel and diverse mechanical design on joint modules in one way or another, they still require the whole robot dynamic model for motion control, and modularity offered in the mechanical side does not offer any advantage in the control design. In this work, a modular distributed control technique is formulated for modular and reconfigurable robots that can instantly adapt to robot reconfigurations. Under this control methodology, a modular and reconfigurable robot is stabilized joint by joint, and modules can be added or removed without the need of re-tuning the controller. Model uncertainties associated with load and links are compensated by the use of joint torque sensors. Other model uncertainties at each joint module are compensated by a decomposition based robust controller for each module. The proposed distributed control technique offers a 'modular' approach, featuring a unique joint-by-joint control synthesis of the joint modules. Fault tolerance and fault detection are formulated as a decentralized control problem for modular and reconfigurable robots in this thesis work. The modularity of the system is exploited to derive a strategy dependent only on a single joint module, while eliminating the need for the motion states of other joint modules. While the traditional fault tolerant and detection schemes are suitable for robots with the whole dynamic model, this proposed technique is ideal for modular and reconfigurable robots because of its modular nature. The proposed methods have been

  2. Robust uncalibrated visual servoing control based on disturbance observer.

    PubMed

    Ma, Zhe; Su, Jianbo

    2015-11-01

    In this paper, an uncalibrated visual servoing scheme with optimal disturbance rejection performance is proposed based on disturbance observer (DOB). Comparing with traditional uncalibrated methods, which estimate online the hand-eye relationship characterized by varying image Jacobian, the uncertainty of image Jacobian is eliminated via DOB to approach a given nominal model in this paper. By solving a constrained optimization problem transformed into an H∞ control framework, the disturbance rejection performance is optimized while ensuring the robust stability of the closed-loop visual servoing system. The controller is based on the nominal image Jacobian matrix, thus avoiding singularities and local minima. Simulations and experiments show that the proposed scheme performs better in tracking an object than traditional algorithms. The disturbance and image noise rejection performance is verified.

  3. Preliminary demonstration of a robust controller design method

    NASA Technical Reports Server (NTRS)

    Anderson, L. R.

    1980-01-01

    Alternative computational procedures for obtaining a feedback control law which yields a control signal based on measurable quantitites are evaluated. The three methods evaluated are: (1) the standard linear quadratic regulator design model; (2) minimization of the norm of the feedback matrix, k via nonlinear programming subject to the constraint that the closed loop eigenvalues be in a specified domain in the complex plane; and (3) maximize the angles between the closed loop eigenvectors in combination with minimizing the norm of K also via the constrained nonlinear programming. The third or robust design method was chosen to yield a closed loop system whose eigenvalues are insensitive to small changes in the A and B matrices. The relationship between orthogonality of closed loop eigenvectors and the sensitivity of closed loop eigenvalues is described. Computer programs are described.

  4. Robust adaptive cruise control of high speed trains.

    PubMed

    Faieghi, Mohammadreza; Jalali, Aliakbar; Mashhadi, Seyed Kamal-e-ddin Mousavi

    2014-03-01

    The cruise control problem of high speed trains in the presence of unknown parameters and external disturbances is considered. In particular a Lyapunov-based robust adaptive controller is presented to achieve asymptotic tracking and disturbance rejection. The system under consideration is nonlinear, MIMO and non-minimum phase. To deal with the limitations arising from the unstable zero-dynamics we do an output redefinition such that the zero-dynamics with respect to new outputs becomes stable. Rigorous stability analyses are presented which establish the boundedness of all the internal states and simultaneously asymptotic stability of the tracking error dynamics. The results are presented for two common configurations of high speed trains, i.e. the DD and PPD designs, based on the multi-body model and are verified by several numerical simulations.

  5. Improving uptake of influenza vaccination among older people: a randomised controlled trial.

    PubMed Central

    Arthur, Antony J; Matthews, Ruth J; Jagger, Carol; Clarke, Michael; Hipkin, Alison; Bennison, Dean P

    2002-01-01

    BACKGROUND: The uptake of influenza vaccination among older people is suboptimal. Contact with a doctor or nurse is associated with older people deciding to accept influenza vaccination. AIM: To compare different forms of approach in improving uptake of influenza vaccination among patients aged 75 years and over in primary care. DESIGN OF STUDY: Randomised controlled trial. SETTING: One large rural general practice serving the town and surrounding area of Melton Mowbray, Leicestershire. METHOD: All 2,052 patients aged 75 years and over, registered with the practice and not living in nursing/residential homes or sheltered accommodation, were included in the study. One-third of patients were randomised to receive an offer of influenza vaccination as part of an over-75 health check administered by a practice nurse in the patient's home, and two-thirds of patients were randomised to receive a personal letter of invitation to attend an influenza vaccination clinic held at the surgery. The main outcome measure was uptake of influenza vaccination. RESULTS: Six hundred and eighty patients were randomised to the health check arm of the trial and 1,372 were randomised to receive a personal letter. Of those randomised to the health check arm, 468 received the health check from the nurse. Overall, the difference in influenza vaccination uptake was 6.4% (95% confidence interval [CI] = 2.2% to 10.4%) with 67.9% (n = 932) of those who were sent a personal letter actually receiving the vaccine, compared with 74.3% (n = 505) of those offered a combined health check and influenza vaccination (P = 0.003). CONCLUSION: Combining home-based over- 75 health checks with influenza vaccination can improve uptake among older patients. However this intervention is likely to be costly and its effect on influenza vaccination rates is modest. The difference in uptake is greater among those who do not routinely comeforwardfor vaccination and a more viable option may be to target these patients

  6. Improving uptake of influenza vaccination among older people: a randomised controlled trial.

    PubMed

    Arthur, Antony J; Matthews, Ruth J; Jagger, Carol; Clarke, Michael; Hipkin, Alison; Bennison, Dean P

    2002-09-01

    The uptake of influenza vaccination among older people is suboptimal. Contact with a doctor or nurse is associated with older people deciding to accept influenza vaccination. To compare different forms of approach in improving uptake of influenza vaccination among patients aged 75 years and over in primary care. Randomised controlled trial. One large rural general practice serving the town and surrounding area of Melton Mowbray, Leicestershire. All 2,052 patients aged 75 years and over, registered with the practice and not living in nursing/residential homes or sheltered accommodation, were included in the study. One-third of patients were randomised to receive an offer of influenza vaccination as part of an over-75 health check administered by a practice nurse in the patient's home, and two-thirds of patients were randomised to receive a personal letter of invitation to attend an influenza vaccination clinic held at the surgery. The main outcome measure was uptake of influenza vaccination. Six hundred and eighty patients were randomised to the health check arm of the trial and 1,372 were randomised to receive a personal letter. Of those randomised to the health check arm, 468 received the health check from the nurse. Overall, the difference in influenza vaccination uptake was 6.4% (95% confidence interval [CI] = 2.2% to 10.4%) with 67.9% (n = 932) of those who were sent a personal letter actually receiving the vaccine, compared with 74.3% (n = 505) of those offered a combined health check and influenza vaccination (P = 0.003). Combining home-based over- 75 health checks with influenza vaccination can improve uptake among older patients. However this intervention is likely to be costly and its effect on influenza vaccination rates is modest. The difference in uptake is greater among those who do not routinely comeforwardfor vaccination and a more viable option may be to target these patients.

  7. 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.

  8. Robust reliable control design for networked control system with sampling communication

    NASA Astrophysics Data System (ADS)

    Sakthivel, R.; Santra, Srimanta; Mathiyalagan, K.; Su, Hongye

    2015-12-01

    In this article, the problem of robust exponential stability and reliable stabilisation for a class of continuous-time networked control systems (NCSs) with a sample-data controller and unknown time-varying sampling rate is considered. The analysis is based on average dwell-time, Lyapunov-Krasovskii functional and linear matrix inequality (LMI) technique. The delay-dependent criteria are developed for ensuring the robust exponential stability of the considered NCSs. The obtained conditions are formulated in terms of LMIs that can easily be solved by using standard software packages. Furthermore, the result is extended to study the robust stabilisation for NCS with parameter uncertainties. A state feedback controller is constructed in terms of the solution to a set of LMIs, which guarantee the robust exponential stabilisation of NCS and the controller. Finally, numerical examples are presented to illustrate the effectiveness of the obtained results.

  9. To condition or not condition? Analysing ‘change’ in longitudinal randomised controlled trials

    PubMed Central

    Coffman, Cynthia J; Edelman, David; Woolson, Robert F

    2016-01-01

    Objective The statistical analysis for a 2-arm randomised controlled trial (RCT) with a baseline outcome followed by a few assessments at fixed follow-up times typically invokes traditional analytic methods (eg, analysis of covariance (ANCOVA), longitudinal data analysis (LDA)). ‘Constrained’ longitudinal data analysis (cLDA) is a well-established unconditional technique that constrains means of baseline to be equal between arms. We use an analysis of fasting lipid profiles from the Group Medical Clinics (GMC) longitudinal RCT on patients with diabetes to illustrate applications of ANCOVA, LDA and cLDA to demonstrate theoretical concepts of these methods including the impact of missing data. Methods For the analysis of the illustrated example, all models were fit using linear mixed models to participants with only complete data and to participants using all available data. Results With complete data (n=195), 95% CI coverage are equivalent for ANCOVA and cLDA with an estimated 11.2 mg/dL (95% CI −19.2 to −3.3; p=0.006) lower mean low-density lipoprotein (LDL) cholesterol in GMC compared with usual care. With all available data (n=233), applying the cLDA model yielded an LDL improvement of 8.9 mg/dL (95% CI −16.7 to −1.0; p=0.03) for GMC compared with usual care. The less efficient, LDA analysis yielded an LDL improvement of 7.2 mg/dL (95% CI −17.2 to 2.8; p=0.15) for GMC compared with usual care. Conclusions Under reasonable missing data assumptions, cLDA will yield efficient treatment effect estimates and robust inferential statistics. It may be regarded as the method of choice over ANCOVA and LDA. PMID:28039292

  10. Robust parameter design for automatically controlled systems and nanostructure synthesis

    NASA Astrophysics Data System (ADS)

    Dasgupta, Tirthankar

    2007-12-01

    This research focuses on developing comprehensive frameworks for developing robust parameter design methodology for dynamic systems with automatic control and for synthesis of nanostructures. In many automatically controlled dynamic processes, the optimal feedback control law depends on the parameter design solution and vice versa and therefore an integrated approach is necessary. A parameter design methodology in the presence of feedback control is developed for processes of long duration under the assumption that experimental noise factors are uncorrelated over time. Systems that follow a pure-gain dynamic model are considered and the best proportional-integral and minimum mean squared error control strategies are developed by using robust parameter design. The proposed method is illustrated using a simulated example and a case study in a urea packing plant. This idea is also extended to cases with on-line noise factors. The possibility of integrating feedforward control with a minimum mean squared error feedback control scheme is explored. To meet the needs of large scale synthesis of nanostructures, it is critical to systematically find experimental conditions under which the desired nanostructures are synthesized reproducibly, at large quantity and with controlled morphology. The first part of the research in this area focuses on modeling and optimization of existing experimental data. Through a rigorous statistical analysis of experimental data, models linking the probabilities of obtaining specific morphologies to the process variables are developed. A new iterative algorithm for fitting a Multinomial GLM is proposed and used. The optimum process conditions, which maximize the above probabilities and make the synthesis process less sensitive to variations of process variables around set values, are derived from the fitted models using Monte-Carlo simulations. The second part of the research deals with development of an experimental design methodology, tailor

  11. Conductive Education as a Method of Stroke Rehabilitation: A Single Blinded Randomised Controlled Feasibility Study

    PubMed Central

    Jutley-Neilson, Jagjeet; Russell, Nicholas C. C.; Sackley, Catherine M.

    2016-01-01

    Background. Conductive Education for stroke survivors has shown promise but randomised evidence is unavailable. This study assessed the feasibility of a definitive randomised controlled trial to evaluate efficacy. Methods. Adult stroke survivors were recruited through local community notices. Those completing the baseline assessment were randomised using an online program and group allocation was independent. Intervention group participants received 10 weekly 1.5-hour sessions of Conductive Education at the National Institute of Conductive Education in Birmingham, UK. The control group participants attended two group meetings. The study evaluated the feasibility of recruitment procedures, delivery of the intervention, retention of participants, and appropriateness of outcome measures and data collection methods. Independent assessments included the Barthel Index, the Stroke Impact Scale, the Timed Up and Go test, and the Hospital Anxiety and Depression Scale. Results. Eighty-two patients were enrolled; 77 completed the baseline assessment (46 men, mean age 62.1 yrs.) and were randomised. 70 commenced the intervention (n = 37) or an equivalent waiting period (n = 33). 32/37 completed the 10-week training and 32/33 the waiting period. There were no missing items from completed questionnaires and no adverse events. Discussion. Recruitment, intervention, and assessment methods worked well. Transport issues for intervention and assessment appointments require review. Conclusion. A definitive trial is feasible. This trial is registered with ISRCTN84064492. PMID:27418997

  12. Robust control of mitotic spindle orientation in the developing epidermis

    PubMed Central

    Poulson, Nicholas D.

    2010-01-01

    Progenitor cells must balance self-amplification and production of differentiated progeny during development and homeostasis. In the epidermis, progenitors divide symmetrically to increase surface area and asymmetrically to promote stratification. In this study, we show that individual epidermal cells can undergo both types of division, and therefore, the balance is provided by the sum of individual cells’ choices. In addition, we define two control points for determining a cell’s mode of division. First is the expression of the mouse Inscuteable gene, which is sufficient to drive asymmetric cell division (ACD). However, there is robust control of division orientation as excessive ACDs are prevented by a change in the localization of NuMA, an effector of spindle orientation. Finally, we show that p63, a transcriptional regulator of stratification, does not control either of these processes. These data have uncovered two important regulatory points controlling ACD in the epidermis and allow a framework for analysis of how external cues control this important choice. PMID:21098114

  13. 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

  14. 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.

  15. Robust Diffeomorphic Mapping via Geodesically Controlled Active Shapes

    PubMed Central

    Tward, Daniel J.; Ma, Jun; Miller, Michael I.; Younes, Laurent

    2013-01-01

    This paper presents recent advances in the use of diffeomorphic active shapes which incorporate the conservation laws of large deformation diffeomorphic metric mapping. The equations of evolution satisfying the conservation law are geodesics under the diffeomorphism metric and therefore termed geodesically controlled diffeomorphic active shapes (GDAS). Our principal application in this paper is on robust diffeomorphic mapping methods based on parameterized surface representations of subcortical template structures. Our parametrization of the GDAS evolution is via the initial momentum representation in the tangent space of the template surface. The dimension of this representation is constrained using principal component analysis generated from training samples. In this work, we seek to use template surfaces to generate segmentations of the hippocampus with three data attachment terms: surface matching, landmark matching, and inside-outside modeling from grayscale T1 MR imaging data. This is formulated as an energy minimization problem, where energy describes shape variability and data attachment accuracy, and we derive a variational solution. A gradient descent strategy is employed in the numerical optimization. For the landmark matching case, we demonstrate the robustness of this algorithm as applied to the workflow of a large neuroanatomical study by comparing to an existing diffeomorphic landmark matching algorithm. PMID:23690757

  16. Robust Diffeomorphic Mapping via Geodesically Controlled Active Shapes.

    PubMed

    Tward, Daniel J; Ma, Jun; Miller, Michael I; Younes, Laurent

    2013-01-01

    This paper presents recent advances in the use of diffeomorphic active shapes which incorporate the conservation laws of large deformation diffeomorphic metric mapping. The equations of evolution satisfying the conservation law are geodesics under the diffeomorphism metric and therefore termed geodesically controlled diffeomorphic active shapes (GDAS). Our principal application in this paper is on robust diffeomorphic mapping methods based on parameterized surface representations of subcortical template structures. Our parametrization of the GDAS evolution is via the initial momentum representation in the tangent space of the template surface. The dimension of this representation is constrained using principal component analysis generated from training samples. In this work, we seek to use template surfaces to generate segmentations of the hippocampus with three data attachment terms: surface matching, landmark matching, and inside-outside modeling from grayscale T1 MR imaging data. This is formulated as an energy minimization problem, where energy describes shape variability and data attachment accuracy, and we derive a variational solution. A gradient descent strategy is employed in the numerical optimization. For the landmark matching case, we demonstrate the robustness of this algorithm as applied to the workflow of a large neuroanatomical study by comparing to an existing diffeomorphic landmark matching algorithm.

  17. High-throughput electrical characterization for robust overlay lithography control

    NASA Astrophysics Data System (ADS)

    Devender, Devender; Shen, Xumin; Duggan, Mark; Singh, Sunil; Rullan, Jonathan; Choo, Jae; Mehta, Sohan; Tang, Teck Jung; Reidy, Sean; Holt, Jonathan; Kim, Hyung Woo; Fox, Robert; Sohn, D. K.

    2017-03-01

    Realizing sensitive, high throughput and robust overlay measurement is a challenge in current 14nm and advanced upcoming nodes with transition to 300mm and upcoming 450mm semiconductor manufacturing, where slight deviation in overlay has significant impact on reliability and yield1). Exponentially increasing number of critical masks in multi-patterning lithoetch, litho-etch (LELE) and subsequent LELELE semiconductor processes require even tighter overlay specification2). Here, we discuss limitations of current image- and diffraction- based overlay measurement techniques to meet these stringent processing requirements due to sensitivity, throughput and low contrast3). We demonstrate a new electrical measurement based technique where resistance is measured for a macro with intentional misalignment between two layers. Overlay is quantified by a parabolic fitting model to resistance where minima and inflection points are extracted to characterize overlay control and process window, respectively. Analyses using transmission electron microscopy show good correlation between actual overlay performance and overlay obtained from fitting. Additionally, excellent correlation of overlay from electrical measurements to existing image- and diffraction- based techniques is found. We also discuss challenges of integrating electrical measurement based approach in semiconductor manufacturing from Back End of Line (BEOL) perspective. Our findings open up a new pathway for accessing simultaneous overlay as well as process window and margins from a robust, high throughput and electrical measurement approach.

  18. Robust Thermal Control of Propulsion Lines for Space Missions

    NASA Technical Reports Server (NTRS)

    Bhandari, Pradeep

    2011-01-01

    A document discusses an approach to insulating propulsion lines for spacecraft. In spacecraft that have propulsion lines that are located externally with open bus architecture, the lines are typically insulated by Multi Layer Insulation (MLI) blankets. MLI on propulsion lines tends to have large and somewhat random variances in its heat loss properties (effective emittance) from one location to the next, which makes it an un-robust approach to control propulsion line temperatures. The approach described here consists of a clamshell design in which the inner surface of the shell is coated with low-emissivity aluminized Kapton tape, and the outer surface is covered with black tape. This clamshell completely encloses the propulsion line. The line itself is covered with its heater, which in turn, is covered completely with black tape. This approach would be low in heater power needs because even though the outer surface of the prop line (and its heater) is covered with black tape as well as the outer surface of the clamshell, the inner surface of the clamshell is covered with low-emissivity aluminized Kapton tape. Hence, the heat loss from the line will be small and comparable to the MLI based one. In terms of contamination changing the radiative properties of surfaces, since the clamshell s inner surface is always protected during handling and is only installed after all the work on the prop line has been completed, the controlling surface, which is the clamshell s inner surface, is always in pristine condition. This proposed design allows for a much more deterministic and predictable design using a very simple and implementable approach for thermal control. It also uses low heater power and is robust to handling and contamination during and after implementation.

  19. Results of a feasibility randomised controlled trial (RCT) for WATCH IT: a programme for obese children and adolescents

    PubMed Central

    Farrin, Amanda; Christie, Deborah; Jebb, Susan A; Cooper, Ashley R; Rudolf, Mary

    2011-01-01

    Background In the evaluation of childhood obesity interventions, few researchers undertake a rigorous feasibility stage in which the design and procedures of the evaluation process are examined. Consequently, phase III studies often demonstrate methodological weaknesses. Purpose Our aim was to conduct a feasibility trial of the evaluation of WATCH IT, a community obesity intervention for children and adolescents. We sought to determine an achievable recruitment rate; acceptability of randomisation, assessment procedures, and dropout rate; optimal outcome measures for the definitive trial; and a robust sample size calculation. Method Our goal was to recruit 70 participants over 6 months, randomise them to intervention or control group, and retain participation for 12 months. Assessments were taken prior to randomisation and after 6 and 12 months. Procedures mirrored those intended for a full-scale trial, but multiple measures of similar outcomes were included as a means to determine those most appropriate for future research. Acceptability of the research and impact of the research on the programme were ascertained through interviewing participants and staff. Results We recruited 70 participants and found that randomisation and data collection procedures were acceptable. Self-referral (via media promotion) was more effective than professional referral. Blinding of assessors was sustained to a reasonable degree, and optimal outcome measures for a full-scale trial were identified. Estimated sample size was significantly greater than sample sized reported in published trials. There was some negative impact on the existing programme as a result of the research, a lesson for designers of future trials. Limitations We successfully recruited socially disadvantaged families, but the majority of families were of White British nationality. The composition of the participants was an added valuable lesson, suggesting that recruitment strategies to obtain a more heterogeneous

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. The Parameterization of All Robust Stabilizing Simple Repetitive Controllers

    NASA Astrophysics Data System (ADS)

    Yamada, Kou; Sakanushi, Tatsuya; Ando, Yoshinori; Hagiwara, Takaaki; Murakami, Iwanori; Takenaga, Hiroshi; Tanaka, Hiroshi; Matsuura, Shun

    The modified repetitive control system is a type of servomechanism for the periodic reference input. That is, the modified repetitive control system follows the periodic reference input with small steady state error, even if a periodic disturbance or an uncertainty exists in the plant. Using previously proposed modified repetitive controllers, even if the plant does not include time-delay, transfer functions from the periodic reference input to the output and from the disturbance to the output have infinite numbers of poles. When transfer functions from the periodic reference input to the output and from the disturbance to the output have infinite numbers of poles, it is difficult to specify the input-output characteristic and the disturbance attenuation characteristic. From the practical point of view, it is desirable that the input-output characteristic and the disturbance attenuation characteristic are easily specified. In order to specify the input-output characteristic and the disturbance attenuation characteristic easily, transfer functions from the periodic reference input to the output and from the disturbance to the output are desirable to have finite numbers of poles. From this viewpoint, Yamada et al. proposed the concept of simple repetitive control systems such that the controller works as a modified repetitive controller and transfer functions from the periodic reference input to the output and from the disturbance to the output have finite numbers of poles. In addition, Yamada et al. clarified the parameterization of all stabilizing simple repetitive controllers. However, the method by Yamada et al. cannot be applied for the plant with uncertainty. The purpose of this paper is to propose the parameterization of all robust stabilizing simple repetitive controllers for the plant with uncertainty.

  6. A design method for robust stabilizing simple repetitive control systems

    NASA Astrophysics Data System (ADS)

    Yamada, Kou; Takenaga, Hiroshi; Tanaka, Hiroshi

    2007-12-01

    The modified repetitive control system is a type of servomechanism for the periodic reference input. That is, the modified repetitive control system follows the periodic reference input with small steady state error, even if a periodic disturbance or uncertainty exists in the plant. Using previously proposed modified repetitive controllers, even if the plants does not includes time-delay, the transfer function from the periodic reference input to the output and that from the disturbance to the output have an infinite number of poles. When the transfer function from the periodic reference input to the output and that from the disturbance to the output have an infinite number of poles, it is difficult to specify the input-output characteristic and the disturbance attenuation characteristic. From the practical point of view, it is desirable that the input-output characteristic and the disturbance attenuation characteristic are easily specified. In order to specify the input-output characteristic and the disturbance attenuation characteristic easily, the transfer function from the periodic reference input to the output and that from the disturbance to the output are desirable to have a finite number of poles. Yamada et al. proposed the concept of simple repetitive control systems such that the controller works as a modified repetitive controller and the transfer function from the periodic reference input to the output and that from the disturbance to the output have a finite number of poles. In addition, Yamada et al. clarified the parametrization of all stabilizing simple repetitive controllers. However the method by Yamada et al. cannot be applied for the plant with uncertainty. The purpose of this paper is to propose the parametrization of all robust stabilizing simple repetitive controllers for the plant with uncertainty.

  7. Lyapunov function-based control laws for revolute robot arms - Tracking control, robustness, and adaptive control

    NASA Technical Reports Server (NTRS)

    Wen, John T.; Kreutz-Delgado, Kenneth; Bayard, David S.

    1992-01-01

    A new class of joint level control laws for all-revolute robot arms is introduced. The analysis is similar to a recently proposed energy-like Liapunov function approach, except that the closed-loop potential function is shaped in accordance with the underlying joint space topology. This approach gives way to a much simpler analysis and leads to a new class of control designs which guarantee both global asymptotic stability and local exponential stability. When Coulomb and viscous friction and parameter uncertainty are present as model perturbations, a sliding mode-like modification of the control law results in a robustness-enhancing outer loop. Adaptive control is formulated within the same framework. A linear-in-the-parameters formulation is adopted and globally asymptotically stable adaptive control laws are derived by simply replacing unknown model parameters by their estimates (i.e., certainty equivalence adaptation).

  8. Development of Control Models and a Robust Multivariable Controller for Surface Shape Control

    SciTech Connect

    Winters, Scott Eric

    2003-06-18

    Surface shape control techniques are applied to many diverse disciplines, such as adaptive optics, noise control, aircraft flutter control and satellites, with an objective to achieve a desirable shape for an elastic body by the application of distributed control forces. Achieving the desirable shape is influenced by many factors, such as, actuator locations, sensor locations, surface precision and controller performance. Building prototypes to complete design optimizations or controller development can be costly or impractical. This shortfall, puts significant value in developing accurate modeling and control simulation approaches. This thesis focuses on the field of adaptive optics, although these developments have the potential for application in many other fields. A static finite element model is developed and validated using a large aperture interferometer system. This model is then integrated into a control model using a linear least squares algorithm and Shack-Hartmann sensor. The model is successfully exercised showing functionality for various wavefront aberrations. Utilizing a verified model shows significant value in simulating static surface shape control problems with quantifiable uncertainties. A new dynamic model for a seven actuator deformable mirror is presented and its accuracy is proven through experiment. Bond graph techniques are used to generate the state space model of the multi-actuator deformable mirror including piezo-electric actuator dynamics. Using this verified model, a robust multi-input multi-output (MIMO) H controller is designed and implemented. This controller proved superior performance as compared to a standard proportional-integral controller (PI) design.

  9. Robust quantum control using smooth pulses and topological winding.

    PubMed

    Barnes, Edwin; Wang, Xin; Das Sarma, S

    2015-08-04

    The greatest challenge in achieving the high level of control needed for future technologies based on coherent quantum systems is the decoherence induced by the environment. Here, we present an analytical approach that yields explicit constraints on the driving field which are necessary and sufficient to ensure that the leading-order noise-induced errors in a qubit's evolution cancel exactly. We derive constraints for two of the most common types of noise that arise in qubits: slow fluctuations of the qubit energy splitting and fluctuations in the driving field itself. By theoretically recasting a phase in the qubit's wavefunction as a topological winding number, we can satisfy the noise-cancelation conditions by adjusting driving field parameters without altering the target state or quantum evolution. We demonstrate our method by constructing robust quantum gates for two types of spin qubit: phosphorous donors in silicon and nitrogen-vacancy centers in diamond.

  10. Robust quantum control using smooth pulses and topological winding

    PubMed Central

    Barnes, Edwin; Wang, Xin; Das Sarma, S.

    2015-01-01

    The greatest challenge in achieving the high level of control needed for future technologies based on coherent quantum systems is the decoherence induced by the environment. Here, we present an analytical approach that yields explicit constraints on the driving field which are necessary and sufficient to ensure that the leading-order noise-induced errors in a qubit’s evolution cancel exactly. We derive constraints for two of the most common types of noise that arise in qubits: slow fluctuations of the qubit energy splitting and fluctuations in the driving field itself. By theoretically recasting a phase in the qubit’s wavefunction as a topological winding number, we can satisfy the noise-cancelation conditions by adjusting driving field parameters without altering the target state or quantum evolution. We demonstrate our method by constructing robust quantum gates for two types of spin qubit: phosphorous donors in silicon and nitrogen-vacancy centers in diamond. PMID:26239195

  11. Identification, Uncertainty Characterization and Robust Control Synthesis Applied to Large Flexible Structures Control

    NASA Technical Reports Server (NTRS)

    Bayard, David S.; Chiang, Richard Y.

    1996-01-01

    This paper demonstrates an approach to frequency domain identification for the explicit purpose of designing robust H(infinity) controllers. The approach transforms raw experimental data into a plant set estimate directly usable by modern robust control design software(e.g., Matlab Robust Control Toolboxes [11][2]). A key issue in control design from raw data is the question of whether the controller will work when applied to the true system. The main feature fo this approach is that the resulting controller in guaranteed to work as designed(when applied to the true system) to a prescribed statistical confidence. While the overall methodology addresses key theoretical issues, it has at the same time been specifically designed to support practical implementations. A simulation example is included to demonstrate the overall approach.

  12. Self Management Activation Randomised Trial for Prostatitis (SMART-P): study protocol for a randomised controlled trial

    PubMed Central

    2011-01-01

    Background Chronic prostatitis otherwise known as chronic pelvic pain syndrome is a common urological diagnosis that causes many men significant morbidity and has a detrimental effect on their quality of life. Standard treatment with antibiotics and simple analgesia are often ineffective and many patients are managed by the chronic pain services. Cognitive behavioural therapy has been shown to be helpful in the management of many chronic diseases and has recently been proposed as an effective treatment for chronic prostatitis. Furthermore, a self management programme administered to groups of men with lower urinary tract symptoms has been shown to be more effective than standard treatments including surgery. Therefore, we have developed a cognitive behavioural therapy programme specifically for men with chronic prostatitis. This novel treatment approach will be compared to conventional therapy in the pain clinic such as atypical analgesia and local anaesthetic injections in the context of a randomised controlled trial. Methods/Design Men will be recruited from general urology outpatient clinics following the exclusion of other diagnoses that could be responsible for their symptoms. Men will be randomised to attend either a self management healthcare and education programme or to pain clinic referral alone. The self management programme will be administered by a clinical psychologist to small groups of men over six consecutive weekly sessions each lasting two hours. Patients will be taught techniques of problem-solving and goal-setting and will learn coping mechanisms and how to modify catastrophic cognition. The primary outcome will be change from baseline in the National Institute of Health Chronic Prostatitis Symptom Index, a validated instrument for the assessment of men with chronic prostatitis. Secondary outcomes include generic quality of life scores and analgesic and drug usage. Outcomes will be assessed at 2, 6 and 12 months. Discussion If this group

  13. Self Management Activation Randomised Trial for Prostatitis (SMART-P): study protocol for a randomised controlled trial.

    PubMed

    Rochester, Mark; Armitage, James; Sanders, Mark; Christmas, Paula

    2011-09-26

    Chronic prostatitis otherwise known as chronic pelvic pain syndrome is a common urological diagnosis that causes many men significant morbidity and has a detrimental effect on their quality of life. Standard treatment with antibiotics and simple analgesia are often ineffective and many patients are managed by the chronic pain services.Cognitive behavioural therapy has been shown to be helpful in the management of many chronic diseases and has recently been proposed as an effective treatment for chronic prostatitis. Furthermore, a self management programme administered to groups of men with lower urinary tract symptoms has been shown to be more effective than standard treatments including surgery.Therefore, we have developed a cognitive behavioural therapy programme specifically for men with chronic prostatitis. This novel treatment approach will be compared to conventional therapy in the pain clinic such as atypical analgesia and local anaesthetic injections in the context of a randomised controlled trial. Men will be recruited from general urology outpatient clinics following the exclusion of other diagnoses that could be responsible for their symptoms. Men will be randomised to attend either a self management healthcare and education programme or to pain clinic referral alone. The self management programme will be administered by a clinical psychologist to small groups of men over six consecutive weekly sessions each lasting two hours. Patients will be taught techniques of problem-solving and goal-setting and will learn coping mechanisms and how to modify catastrophic cognition.The primary outcome will be change from baseline in the National Institute of Health Chronic Prostatitis Symptom Index, a validated instrument for the assessment of men with chronic prostatitis. Secondary outcomes include generic quality of life scores and analgesic and drug usage. Outcomes will be assessed at 2, 6 and 12 months. If this group administered self management programme is

  14. Ear Acupressure for Smoking Cessation: A Randomised Controlled Trial

    PubMed Central

    Zhang, Anthony L.; Di, Yuan Ming; Worsnop, Christopher; May, Brian H.; Da Costa, Cliff; Xue, Charlie C. L.

    2013-01-01

    This study investigated the efficacy and safety of ear acupressure (EAP) as a stand-alone intervention for smoking cessation and the feasibility of this study design. Adult smokers were randomised to receive EAP specific for smoking cessation (SSEAP) or a nonspecific EAP (NSEAP) intervention which is not typically used for smoking cessation. Participants received 8 weekly treatments and were requested to press the five pellets taped to one ear at least three times daily. Participants were followed up for three months. Primary outcome measures were a 7-day point-prevalence cessation rate confirmed by exhaled carbon monoxide and relief of nicotine withdrawal symptoms (NWS). Intention-to-treat analysis was applied. Forty-three adult smokers were randomly assigned to SSEAP (n = 20) or NSEAP (n = 23) groups. The dropout rate was high with 19 participants completing the treatments and 12 remaining at followup. One participant from the SSEAP group had confirmed cessation at week 8 and end of followup (5%), but there was no difference between groups for confirmed cessation or NWS. Adverse events were few and minor. PMID:24191168

  15. A randomised controlled trial of transforaminal endoscopic discectomy vs microdiscectomy.

    PubMed

    Gibson, J N Alaistair; Subramanian, Ashok S; Scott, Chloe E H

    2017-03-01

    Transforaminal endoscopic discectomy (TED) minimises paraspinal muscle damage. The aim of this trial was to compare clinical outcomes of TED to Microdiscectomy (Micro). 143 patients, age 25-70 years and <115 kg, with single level lumbar prolapse and radiculopathy, were recruited and randomised. 70 received TED under conscious sedation and 70 Micro under general anaesthesia. Oswestry Disability Index (ODI), visual analogue scores (VAS) of back and leg pain, and Short Form Health Survey indices (SF-36) were measured preoperatively and at 3, 12 and 24 months. All outcome measures improved significantly in both groups (p < 0.001). Affected side leg pain was lower in the TED group at 2 years (1.9 ± 2.6 vs 3.5 ± 3.1, p = 0.002). Hospital stay was shorter following TED (0.7 ± 0.7 vs 1.4 ± 1.3 days, p < 0.001). Two Micro patients and five TED patients required revision giving a relative risk of revision for TED of 2.62 (95% CI 0.49-14.0). Functional improvements were maintained at 2 years in both groups with less ongoing sciatica after TED. A greater revision rate after TED was offset by a more rapid recovery.

  16. Randomised controlled trial of cisapride in preterm infants

    PubMed Central

    McClure, R; Kristensen, J; Grauaug, A

    1999-01-01

    AIM—To determine the effect of cisapride on gastrointestinal motility in preterm infants.
METHODS—Cisapride (0.2 mg/kg, 8 hourly ) or placebo was given first for seven days in a double blind randomised crossover study of 10 preterm infants. Gastrointestinal motility was assessed on day 3 of each treatment. The half gastric emptying time (GET1/2) was determined by using ultrasonography to measure the decrease in the gastric antral cross sectional area after a feed. The whole gastrointestinal transit time (WGTT) was assessed by timing the transit of carmine red through the gut. Treatments were compared using the Wilcoxon matched pairs signed ranks test.
RESULTS—Median (range) birthweight was 1200 (620, 1450) g and postconceptional age 33 (29, 34) weeks at recruitment. GET1/2 was significantly longer during cisapride treatment than during placebo; the median of the differences (95% confidence interval) was 19.2 (11, 30minutes, p=0.008). WGTT was also longer during cisapride treatment, but the difference was not significant; the median of the differences was 11(−18, 52 hours, p=0.1).
CONCLUSIONS—Cisapride delays gastric emptying and may delay WGTT in preterm infants. Its use to promote gastrointestinal motility in this group cannot be recommended.

 PMID:10212076

  17. Acceptance and commitment therapy for psychosis: randomised controlled trial.

    PubMed

    Shawyer, Frances; Farhall, John; Thomas, Neil; Hayes, Steven C; Gallop, Robert; Copolov, David; Castle, David J

    2017-02-01

    The efficacy of acceptance and commitment therapy (ACT) in psychosis has been reported but not for medication-resistant psychosis. To test the efficacy of ACT in a sample of community-residing patients with persisting psychotic symptoms. (Australian New Zealand Clinical Trials Registry: ACTRN12608000210370.) METHOD: The primary outcome was overall mental state at post-therapy (Positive and Negative Syndrome Scale - total); secondary outcomes were psychotic symptom dimensions and functioning. In total, 96 patients were randomised to ACT (n = 49) or befriending (n = 47). Symptom, functioning and process measures were administered at baseline, post-therapy and 6 months later. There was no group difference on overall mental state. In secondary analyses the ACT group showed greater improvement in positive symptoms and hallucination distress at follow-up: Cohen's d = 0.52 (95% CI 0.07-0.98) and 0.65 (95% CI 0.24-1.06), respectively. Improvements reflected the treatment focus on positive symptoms; however, absence of process-measure changes suggests that the ACT intervention used did not manipulate targeted processes beyond befriending. Symptom-specific therapy refinements, improved investigation of process and attention to cognitive functioning and dose are warranted in future research. © The Royal College of Psychiatrists 2017.

  18. Cisapride reduces neonatal postoperative ileus: randomised placebo controlled trial.

    PubMed

    Lander, A; Redkar, R; Nicholls, G; Lawson, A; Choudhury, S R; Corkery, J J; Gornall, P; Buick, R G; Booth, I W

    1997-09-01

    To assess the efficacy of cisapride in reducing ileus persisting to the tenth postoperative day after neonatal abdominal surgery. A prospective, randomised, double blind trial comparing rectal cisapride (1.4-2.3 mg/kg/day) with placebo over seven days was undertaken in 33 neonates. Seven of 12 (58%) patients receiving placebo and eight of 11 (73%) receiving cisapride achieved a first sustained feed during treatment. Of those receiving cisapride, the first sustained feed occurred at 2.3 days (SEM 0.6) compared with 4.7 days (SEM 0.8) with placebo. By the seventh day the mean daily net enteral balance was 69 (SEM 18) ml/kg in the cisapride subgroup and 17 (SEM 8) ml/kg for those receiving placebo. Stool was passed on 6.3 (SEM 0.4) treatment days in the cisapride subgroup compared with 4.1 (SEM 1.0) treatment days in the placebo subgroup. Cisapride is effective in neonates with a prolonged ileus after abdominal surgery.

  19. Cisapride reduces neonatal postoperative ileus: randomised placebo controlled trial

    PubMed Central

    Lander, A; Redkar, R; Nicholls, G; Lawson, A; Choudhury, S; Corkery, J; Gornall, P; Buick, R; Booth, I

    1997-01-01

    AIM—To assess the efficacy of cisapride in reducing ileus persisting to the tenth postoperative day after neonatal abdominal surgery.
METHODS—A prospective, randomised, double blind trial comparing rectal cisapride (l.4-2.3 mg/kg/day) with placebo over seven days was undertaken in 33 neonates.
RESULTS—Seven of 12 (58%) patients receiving placebo and eight of 11 (73%) receiving cisapride achieved a first sustained feed during treatment. Of those receiving cisapride, the first sustained feed occurred at 2.3 days (SEM 0.6) compared with 4.7 days (SEM 0.8) with placebo. By the seventh day the mean daily net enteral balance was 69 (SEM 18) ml/kg in the cisapride subgroup and 17 (SEM 8) ml/kg for those receiving placebo. Stool was passed on 6.3 (SEM 0.4) treatment days in the cisapride subgroup compared with 4.1 (SEM 1.0) treatment days in the placebo subgroup.
CONCLUSION—Cisapride is effective in neonates with a prolonged ileus after abdominal surgery.

 Keywords: cisapride; gastroschisis; postoperative ileus; prokinesis PMID:9377133

  20. 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

  1. A Robust Reinforcement Learning Control Design Method for Nonlinear System with Partially Unknown Structure

    NASA Astrophysics Data System (ADS)

    Nakano, Kazuhiro; Obayashi, Masanao; Kuremoto, Takashi; Kobayashi, Kunikazu

    We propose a robust control system which has robustness for disturbance and can deal with a nonlinear system with partially unknown structure by fusing reinforcement learning and robust control theory. First, we solved an optimal control problem without using unknown part of functions of the system, using neural network and the repetition learning of reinforcement learning algorithm. Second, we built the robust reinforcement learning control system which permits uncertainty and has robustness for disturbance by fusing the idea of H infinity control theory with above system.

  2. Randomised control trial of tongue acupuncture versus sham acupuncture in improving functional outcome in cerebral palsy.

    PubMed

    Sun, J G; Ko, C H; Wong, V; Sun, X R

    2004-07-01

    Traditional Chinese medicine (TCM) has been used historically in the treatment of cerebral palsy (CP). We investigated the efficacy of acupuncture in improving the motor function of children with CP. A randomised control trial was conducted to assess the effect of tongue acupuncture (TAC) in 33 CP children. The subjects were randomised to treatment (n = 22) with TAC or control (n = 11). Clinical outcome was evaluated using the gross motor function measure (GMFM) and the pediatric evaluation of disability inventory (PEDI). The increase in mean GMFM score was significantly greater in the treatment than in the control group (p = 0.042). An improvement in motor function of CP subjects is seen following a short course of acupuncture.

  3. Robust Task Space Trajectory Tracking Control of Robotic Manipulators

    NASA Astrophysics Data System (ADS)

    Galicki, M.

    2016-08-01

    This work deals with the problem of the accurate 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 end-effector. Furthermore, the movement is to be accomplished in such a way as to reduce 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 propose a class of chattering-free robust 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.

  4. Robust control of underactuated manipulators: Analysis and implementation

    NASA Astrophysics Data System (ADS)

    Bergerman, Marcel; Xu, Yangsheng

    1994-05-01

    Underactuated manipulators are robot manipulators composed of both active and passive joints. The advantages of using such systems reside in the fact that they weigh less and consume less energy than their fully-actuated counterparts, thus being useful for applications such as space robotics. Another interest resides in the reliability or fault-tolerant design of fully-actuated manipulators. If any of the joint actuators of such a device fails, an entire operation may have to be aborted because of the loss of one or more degrees of freedom. The methodology proposed in this paper uses the dynamic coupling between the passive joints and the active joints, and controls the active ones in order to bring the passive joint angles to a desired set-point. Therefore, the control law and the performance of the system are completely dependent on the dynamic model. Since it is difficult to obtain the exact dynamic model of the system in general, considerable position errors and even instability can result in some cases. In this paper, we propose a variable structure controller to provide the system with the robustness necessary to perform tasks regardless of the modelling errors. Case studies are provided as a means of illustration.

  5. Robust, Flexible Motion Control for the Mars Explorer Rovers

    NASA Technical Reports Server (NTRS)

    Maimone, Mark; Biesiadecki, Jeffrey

    2007-01-01

    The Mobility Flight Software, running on computers aboard the Mars Explorer Rover (MER) robotic vehicles Spirit and Opportunity, affords the robustness and flexibility of control to enable safe and effective operation of these vehicles in traversing natural terrain. It can make the vehicles perform specific maneuvers commanded from Earth, and/or can autonomously administer multiple aspects of mobility, including choice of motion, measurement of actual motion, and even selection of targets to be approached. Motion of a vehicle can be commanded by use of multiple layers of control, ranging from motor control at a low level, direct drive operations (e.g., motion along a circular arc, motion along a straight line, or turn in place) at an intermediate level to goal-position driving (that is, driving to a specified location) at a high level. The software can also perform high-level assessment of terrain and selection of safe paths across the terrain: this involves processing of the digital equivalent of a local traversability map generated from images acquired by stereoscopic pairs of cameras aboard the vehicles. Other functions of the software include interacting with the rest of the MER flight software and performing safety checks.

  6. Robustness and control of a magnetically levitated transportation system

    NASA Astrophysics Data System (ADS)

    Oleszczuk, Grzegorz

    2006-04-01

    Electromagnetic suspension of Magnetic Levitation Vehicles (Maglev) has been studied for many years as an alternative to wheel-on rail transportation systems. In this work, design and implementation of control systems for a Maglev laboratory experiment and a Maglev vehicle under development at Old Dominion University are described. Both plants are modeled and simulated with consideration of issues associated with system non-linearity, structural flexibility and electromagnetic force modeling. Discussion concerning different control strategies, namely centralized and decentralized approaches are compared and contrasted in this work. Different types of electromagnetic non-linearities are considered and described to establish a convenient method for modeling such a system. It is shown how a Finite Element structural model can be incorporated into the system to obtain transfer function notation. Influence of the dynamic interaction between the Maglev track and the Maglev vehicle is discussed and supported by both analytical results and theoretical examples. Finally, several control laws designed to obtain stable and robust levitation are explored in detail.

  7. 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

  8. Identification and robust control of linear parameter-varying systems

    NASA Astrophysics Data System (ADS)

    Lee, Lawton Hubert

    This dissertation deals with linear parameter-varying (LPV) systems: linear dynamic systems that depend on time-varying parameters. These systems appear in gain scheduling problems, and much recent research has been devoted to their prospective usefulness for systematic gain scheduling. We primarily focus on robust control of uncertain LPV systems and identification of LPV systems that are modelable as linear-fractional transformations (LFTs). Using parameter-dependent quadratic Lyapunov functions, linear matrix inequalities (LMIs), and scaled small-gain arguments, we define notions of stability and induced-{cal L}sb2 performance for uncertain LPV systems whose parameters and rates of parameter variation satisfy given bounds. The performance criterion involves integral quadratic constraints and implies naturally parameter-dependent induced-{cal L}sb2 norm bounds. We formulate and solve an {cal H}sb{infty}-like control problem for an LPV plant with measurable parameters and an "Output/State Feedback" structure: the feedback outputs include some noiselessly measured states. Necessary and sufficient solvability conditions reduce to LMIs that can be solved approximately using finite-dimensional convex programming. Reduced-order LPV controllers are constructed from the LMI solutions. A D-K iteration-like procedure provides robustness to structured, time-varying, parametric uncertainty. The design method is applied to a motivating example: flight control for the F-16 VISTA throughout its subsonic flight envelope. Parameter-dependent weights and {cal H}sb{infty} design principles describe the performance objectives. Closed-loop responses exhibited by nonlinear simulations indicate satisfactory flying qualities. Identification of linear-fractional LPV systems is treated using maximum-likelihood parameter estimation. Computing the gradient and Hessian of a maximum-likelihood cost function reduces to simulating one LPV filter per identified parameter. We use nonlinear

  9. A multicentre, randomised intervention study of the Paediatric Early Warning Score: study protocol for a randomised controlled trial.

    PubMed

    Jensen, Claus Sixtus; Aagaard, Hanne; Olesen, Hanne Vebert; Kirkegaard, Hans

    2017-06-08

    Patients' evolving critical illness can be predicted and prevented. However, failure to identify the signs of critical illness and subsequent lack of appropriate action for patients developing acute and critical illness remain a problem. Challenges in assessing whether a child is critically ill may be due to children's often uncharacteristic symptoms of serious illness. Children may seem relatively unaffected until shortly before circulatory and respiratory failure and cardiac arrest. The Bedside Paediatric Early Warning Score has been validated in a large multinational study and is used in two regions in Denmark. However, healthcare professionals experience difficulties in relation to measuring blood pressure and to the lack of assessment of children's level of consciousness. In addition, is it noteworthy that in 23,288-hour studies, all seven items of the Bedside Paediatric Early Warning Score were recorded in only 5.1% of patients. This trial aims to compare two Paediatric Early Warning Score (PEWS) models to identify the better model for identifying acutely and critically ill children. The hypothesis is that the Central Denmark Region PEWS model is superior to the Bedside PEWS in terms of reducing unplanned transfers to intensive care or transfers from regional hospitals to the university hospital among already hospitalised children. This is a multicentre, randomised, controlled clinical trial where children are allocated to one of two different PEWS models. The study involves all paediatric departments and one emergency department in the Central Denmark Region. The primary outcome is unplanned transfer to the paediatric intensive care unit or transfer from regional hospitals to the university hospital. Based on preliminary data, 14,000 children should be included to gain a power of 80% (with a 5% significance level) and to detect a clinically significant difference of 30% of unplanned transfers to intensive care or from regional hospitals to the paediatric

  10. Chinese Obstetrics & Gynecology journal club: a randomised controlled trial

    PubMed Central

    Tsui, Ilene K; Dodson, William C; Kunselman, Allen R; Kuang, Hongying; Han, Feng-Juan; Legro, Richard S; Wu, Xiao-Ke

    2016-01-01

    Objectives To assess whether a journal club model could improve comprehension and written and spoken medical English in a population of Chinese medical professionals. Setting and participants The study population consisted of 52 medical professionals who were residents or postgraduate master or PhD students in the Department of Obstetrics and Gynecology, Heilongjiang University of Chinese Medicine, China. Intervention After a three-part baseline examination to assess medical English comprehension, participants were randomised to either (1) an intensive journal club treatment arm or (2) a self-study group. At the conclusion of the 8-week intervention participants (n=52) were re-tested with new questions. Outcome measures The primary outcome was the change in score on a multiple choice examination. Secondary outcomes included change in scores on written and oral examinations which were modelled on the Test of English as a Foreign Language (TOEFL). Results Both groups had improved scores on the multiple choice examination without a statistically significant difference between them (90% power). However, there was a statistically significant difference between the groups in mean improvement in scores for both written (95% CI 1.1 to 5.0; p=0.003) and spoken English (95% CI 0.06 to 3.7; p=0.04) favouring the journal club intervention. Conclusions Interacting with colleagues and an English-speaking facilitator in a journal club improved both written and spoken medical English in Chinese medical professionals. Journal clubs may be suitable for use as a self-sustainable teaching model to improve fluency in medical English in foreign medical professionals. Trial registration number NCT01844609. PMID:26823180

  11. Metacognitive training for schizophrenia: a multicentre randomised controlled trial.

    PubMed

    Briki, Malick; Monnin, Julie; Haffen, Emmanuel; Sechter, Daniel; Favrod, Jérôme; Netillard, Christian; Cheraitia, Elisabeth; Marin, Karine; Govyadovskaya, Svetlana; Tio, Grégory; Bonin, Bernard; Chauvet-Gelinier, Jean-Christophe; Leclerc, Stéphanie; Hodé, Yann; Vidailhet, Pierre; Berna, Fabrice; Bertschy, Anna Zinetti; Vandel, Pierre

    2014-08-01

    A psychotherapeutic approach for schizophrenia is now recommended as an adjuvant for psychopharmacology, since antipsychotic medications only have a partial impact especially as regards positive symptoms and insight. In addition, cognitive distortions and the lack of metacognitive skills might increase positive symptoms leading to poor social functioning. This underlines the need for specific approaches which target cognitive processes relevant for insight, and abilities in metacognition. Metacognitive training (MCT) is a structured group intervention, which enhances a patient's reflection on cognitive biases and improves problem-solving. The aim of our study was to assess MCTs' short term impact on insight, symptoms and quality of life. Fifty patients with schizophrenia or schizoaffective disorders and persistent positive symptoms (delusions or hallucinations) were enrolled in the study. After baseline assessment participants were randomised either to supportive therapy or MCT. Both groups used the same design (1h-session twice a week during 8weeks) although the basic knowledge given to participants was different between interventions. Participants were assessed at eight weeks based on the Scale to Assess Unawareness of Mental Disorder, Positive and Negative Syndrome Scale (PANSS), Psychotic Symptom Rating Scales, the Calgary Depression Scale for Schizophrenia and the Quality of Life Scale. Between-group differences were significant in favour of MCT on the PANSS positive scale. Between-group differences in post- and pre-test values showed a trend in favour of MCT for insight on hallucinations. Results of our study indicate that the MCT has an effect on reducing positive symptomatology, and a trend impact on insight and social functioning.

  12. Randomised controlled trial of nicotine chewing-gum.

    PubMed Central

    Jarvis, M J; Raw, M; Russell, M A; Feyerabend, C

    1982-01-01

    The effectiveness of 2 mg nicotine chewing-gum as an aid to stopping smoking was compared with a placebo containing 1 mg nicotine, but unbuffered, in a double-blind randomised trial. Of 58 subjects given the active gum, 27 (47%) were not smoking at one-year follow-up compared with 12 (21%) of the 58 subjects treated with placebo (p less than 0.025). By the most stringent criterion of outcome, 18 (31%) subjects in the active treatment group and eight (14%) in the placebo group had not smoked at all from the start of treatment to follow-up at one year (p less than 0.05). Subjects receiving the active gum experienced less severe withdrawal symptoms and rated their gum as more helpful than did the placebo group. Minor side effects were common but only gastric symptoms were more frequent with the active gum. Subjects receiving active gum used it for longer than those receiving placebo but most stopped using it within six months and only four (7%) developed longer-term dependence. The number of gums used daily correlated significantly with pretreatment blood nicotine concentrations in the active treatment group and with pretreatment cigarette consumption in the placebo group. A lower pretreatment blood nicotine value was the best predictor of success at one year (p less than 0.001) but there was no significant relation to cigarette consumption, sex, and social class. The results clearly confirm the usefulness of nicotine chewing-gum as an aid to stopping smoking and imply a definite role for nicotine in cigarette dependence and withdrawal. Successful use of the gum requires careful attention to subjects' expectations and clear instructions on how to use it. PMID:6809161

  13. Chinese Obstetrics & Gynecology journal club: a randomised controlled trial.

    PubMed

    Tsui, Ilene K; Dodson, William C; Kunselman, Allen R; Kuang, Hongying; Han, Feng-Juan; Legro, Richard S; Wu, Xiao-Ke

    2016-01-28

    To assess whether a journal club model could improve comprehension and written and spoken medical English in a population of Chinese medical professionals. The study population consisted of 52 medical professionals who were residents or postgraduate master or PhD students in the Department of Obstetrics and Gynecology, Heilongjiang University of Chinese Medicine, China. After a three-part baseline examination to assess medical English comprehension, participants were randomised to either (1) an intensive journal club treatment arm or (2) a self-study group. At the conclusion of the 8-week intervention participants (n=52) were re-tested with new questions. The primary outcome was the change in score on a multiple choice examination. Secondary outcomes included change in scores on written and oral examinations which were modelled on the Test of English as a Foreign Language (TOEFL). Both groups had improved scores on the multiple choice examination without a statistically significant difference between them (90% power). However, there was a statistically significant difference between the groups in mean improvement in scores for both written (95% CI 1.1 to 5.0; p=0.003) and spoken English (95% CI 0.06 to 3.7; p=0.04) favouring the journal club intervention. Interacting with colleagues and an English-speaking facilitator in a journal club improved both written and spoken medical English in Chinese medical professionals. Journal clubs may be suitable for use as a self-sustainable teaching model to improve fluency in medical English in foreign medical professionals. NCT01844609. 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/

  14. 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

  15. 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.

  16. Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials

    PubMed Central

    Smith, Gordon C S; Pell, Jill P

    2003-01-01

    Objectives To determine whether parachutes are effective in preventing major trauma related to gravitational challenge. Design Systematic review of randomised controlled trials. Data sources: Medline, Web of Science, Embase, and the Cochrane Library databases; appropriate internet sites and citation lists. Study selection: Studies showing the effects of using a parachute during free fall. Main outcome measure Death or major trauma, defined as an injury severity score > 15. Results We were unable to identify any randomised controlled trials of parachute intervention. Conclusions As with many interventions intended to prevent ill health, the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials. Advocates of evidence based medicine have criticised the adoption of interventions evaluated by using only observational data. We think that everyone might benefit if the most radical protagonists of evidence based medicine organised and participated in a double blind, randomised, placebo controlled, crossover trial of the parachute. PMID:14684649

  17. 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

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

    PubMed

    Corrigan, Neil; Bankart, Michael J G; Gray, Laura J; Smith, Karen L

    2014-05-24

    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. 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. 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. 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 include avoidance of cluster merges where

  19. Randomised controlled trial to evaluate early discharge scheme for patients with stroke.

    PubMed Central

    Rudd, A. G.; Wolfe, C. D.; Tilling, K.; Beech, R.

    1997-01-01

    OBJECTIVE: To assess the clinical effectiveness of an early discharge policy for patients with stroke by using a community based rehabilitation team. DESIGN: Randomised controlled trial to compare conventional care with an early discharge policy. SETTING: Two teaching hospitals in inner London. SUBJECTS: 331 medically stable patients with stroke (mean age 71) who lived alone and were able to transfer independently or who lived with a resident carer and were able to transfer with help. INTERVENTIONS: 167 patients received specialist community rehabilitation for up to 3 months after randomisation. 164 patients continued with conventional hospital and community care. MAIN OUTCOME MEASURES: Barthel score at 12 months. Secondary outcomes measured impairment with motoricity index, minimental state examination, and Frenchay aphasia screening test; disability with the Rivermead activity of daily living scales, hospital anxiety and depression scale, and 5 m walk; handicap with the Nottingham health profile; carer stress with caregiver strain index and patient and carer satisfaction. The main process measure was length of stay after randomisation. RESULTS: One year after randomisation no significant differences in clinical outcomes were found apart from increased satisfaction with hospital care in the community therapy group. Length of stay after randomisation in the community therapy group was significantly reduced (12 v 18 days; P < 0.0001). Patients with impairments were more likely to receive treatment in the community therapy group. CONCLUSIONS: Early discharge with specialist community rehabilitation after stroke is feasible, as clinically effective as conventional care, and acceptable to patients. Considerable reductions in use of hospital beds are achievable. PMID:9366727

  20. Randomised controlled trials may underestimate drug effects: balanced placebo trial design.

    PubMed

    Lund, Karen; Vase, Lene; Petersen, Gitte L; Jensen, Troels S; Finnerup, Nanna B

    2014-01-01

    It is an inherent assumption in randomised controlled trials that the drug effect can be estimated by subtracting the response during placebo from the response during active drug treatment. To test the assumption of additivity. The primary hypothesis was that the total treatment effect is smaller than the sum of the drug effect and the placebo effect. The secondary hypothesis was that non-additivity was most pronounced in participants with large placebo effects. We used a within-subject randomised blinded balanced placebo design and included 48 healthy volunteers (50% males), mean (SD) age 23.4 (6.2) years. Experimental pain was induced by injections of hypertonic saline into the masseter muscle. Participants received four injections with hypertonic saline along with lidocaine or matching placebo in randomised order: A: received hypertonic saline/told hypertonic saline; B: received hypertonic saline+lidocaine/told hypertonic saline; C: received hypertonic saline+placebo/told hypertonic saline+pain killer; D: received hypertonic saline+lidocaine/told hypertonic saline+pain killer. The primary outcome measure was the area under the curve (AUC, mm(2)) of pain intensity during injections. There was a significant difference between the sum of the drug effect and the placebo effect (mean AUC 6279 mm(2) (95% CI, 4936-7622)) and the total treatment effect (mean AUC 5455 mm(2) (95% CI, 4585-6324)) (P = 0.049). This difference was larger for participants with large versus small placebo effects (P = 0.015), and the difference correlated significantly with the size of the placebo effect (r = 0.65, P = 0.006). Although this study examined placebo effects and not the whole placebo response as in randomised controlled trials, it does suggest that the additivity assumption may be incorrect, and that the estimated drug effects in randomised controlled trials may be underestimated, particularly in studies reporting large placebo responses. The implications for

  1. Randomised Controlled Trials May Underestimate Drug Effects: Balanced Placebo Trial Design

    PubMed Central

    Lund, Karen; Vase, Lene; Petersen, Gitte L.; Jensen, Troels S.; Finnerup, Nanna B.

    2014-01-01

    Background It is an inherent assumption in randomised controlled trials that the drug effect can be estimated by subtracting the response during placebo from the response during active drug treatment. Objective To test the assumption of additivity. The primary hypothesis was that the total treatment effect is smaller than the sum of the drug effect and the placebo effect. The secondary hypothesis was that non-additivity was most pronounced in participants with large placebo effects. Methods We used a within-subject randomised blinded balanced placebo design and included 48 healthy volunteers (50% males), mean (SD) age 23.4 (6.2) years. Experimental pain was induced by injections of hypertonic saline into the masseter muscle. Participants received four injections with hypertonic saline along with lidocaine or matching placebo in randomised order: A: received hypertonic saline/told hypertonic saline; B: received hypertonic saline+lidocaine/told hypertonic saline; C: received hypertonic saline+placebo/told hypertonic saline+pain killer; D: received hypertonic saline+lidocaine/told hypertonic saline+pain killer. The primary outcome measure was the area under the curve (AUC, mm2) of pain intensity during injections. Results There was a significant difference between the sum of the drug effect and the placebo effect (mean AUC 6279 mm2 (95% CI, 4936–7622)) and the total treatment effect (mean AUC 5455 mm2 (95% CI, 4585–6324)) (P = 0.049). This difference was larger for participants with large versus small placebo effects (P = 0.015), and the difference correlated significantly with the size of the placebo effect (r = 0.65, P = 0.006). Conclusion Although this study examined placebo effects and not the whole placebo response as in randomised controlled trials, it does suggest that the additivity assumption may be incorrect, and that the estimated drug effects in randomised controlled trials may be underestimated, particularly in studies reporting large

  2. 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

  3. 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.

  4. Psychodynamic Guided Self-Help for Adult Depression through the Internet: A Randomised Controlled Trial

    PubMed Central

    Johansson, Robert; Ekbladh, Sigrid; Hebert, Amanda; Lindström, Malin; Möller, Sara; Petitt, Eleanor; Poysti, Stephanie; Larsson, Mattias Holmqvist; Rousseau, Andréas; Carlbring, Per; Cuijpers, Pim; Andersson, Gerhard

    2012-01-01

    Background and aims Psychodynamic psychotherapy (PDT) is an effective treatment for major depressive disorder (MDD), but not all clients with MDD can receive psychotherapy. Using the Internet to provide psychodynamic treatments is one way of improving access to psychological treatments for MDD. The aim of this randomised controlled trial was to investigate the efficacy of an Internet-based psychodynamic guided self-help treatment for MDD. Methods Ninety-two participants who were diagnosed with MDD according to the Mini-International Neuropsychiatric Interview were randomised to treatment or an active control. The treatment consisted of nine treatment modules based on psychodynamic principles with online therapist contact. The active control condition was a structured support intervention and contained psychoeducation and scheduled weekly contacts online. Both interventions lasted for 10 weeks. The primary outcome measure was the Beck Depression Inventory-II (BDI-II). Results Mixed-effects model analyses of all randomised participants showed that participants receiving Internet-based PDT made large and superior improvements compared with the active control group on the BDI-II (between-group Cohen's d = 1.11). Treatment effects were maintained at a 10-month follow-up. Conclusions Internet-based psychodynamic guided self-help is an efficacious treatment for MDD that has the potential to increase accessibility and availability of PDT for MDD. Trial Registration Clinicaltrials.gov: NCT01324050 PMID:22741027

  5. Psychodynamic guided self-help for adult depression through the internet: a randomised controlled trial.

    PubMed

    Johansson, Robert; Ekbladh, Sigrid; Hebert, Amanda; Lindström, Malin; Möller, Sara; Petitt, Eleanor; Poysti, Stephanie; Larsson, Mattias Holmqvist; Rousseau, Andréas; Carlbring, Per; Cuijpers, Pim; Andersson, Gerhard

    2012-01-01

    Psychodynamic psychotherapy (PDT) is an effective treatment for major depressive disorder (MDD), but not all clients with MDD can receive psychotherapy. Using the Internet to provide psychodynamic treatments is one way of improving access to psychological treatments for MDD. The aim of this randomised controlled trial was to investigate the efficacy of an Internet-based psychodynamic guided self-help treatment for MDD. Ninety-two participants who were diagnosed with MDD according to the Mini-International Neuropsychiatric Interview were randomised to treatment or an active control. The treatment consisted of nine treatment modules based on psychodynamic principles with online therapist contact. The active control condition was a structured support intervention and contained psychoeducation and scheduled weekly contacts online. Both interventions lasted for 10 weeks. The primary outcome measure was the Beck Depression Inventory-II (BDI-II). Mixed-effects model analyses of all randomised participants showed that participants receiving Internet-based PDT made large and superior improvements compared with the active control group on the BDI-II (between-group Cohen's d = 1.11). Treatment effects were maintained at a 10-month follow-up. Internet-based psychodynamic guided self-help is an efficacious treatment for MDD that has the potential to increase accessibility and availability of PDT for MDD. Clinicaltrials.gov: NCT01324050.

  6. Robustness of DNA Repair through Collective Rate Control

    PubMed Central

    Manders, Erik; von Bornstaedt, Gesa; van Driel, Roel; Höfer, Thomas

    2014-01-01

    DNA repair and other chromatin-associated processes are carried out by enzymatic macromolecular complexes that assemble at specific sites on the chromatin fiber. How the rate of these molecular machineries is regulated by their constituent parts is poorly understood. Here we quantify nucleotide-excision DNA repair in mammalian cells and find that, despite the pathways' molecular complexity, repair effectively obeys slow first-order kinetics. Theoretical analysis and data-based modeling indicate that these kinetics are not due to a singular rate-limiting step. Rather, first-order kinetics emerge from the interplay of rapidly and reversibly assembling repair proteins, stochastically distributing DNA lesion repair over a broad time period. Based on this mechanism, the model predicts that the repair proteins collectively control the repair rate. Exploiting natural cell-to-cell variability, we corroborate this prediction for the lesion-recognition factor XPC and the downstream factor XPA. Our findings provide a rationale for the emergence of slow time scales in chromatin-associated processes from fast molecular steps and suggest that collective rate control might be a widespread mode of robust regulation in DNA repair and transcription. PMID:24499930

  7. Reducing conflict and containment rates on acute psychiatric wards: The Safewards cluster randomised controlled trial.

    PubMed

    Bowers, Len; James, Karen; Quirk, Alan; Simpson, Alan; Stewart, Duncan; Hodsoll, John

    2015-09-01

    Acute psychiatric wards manage patients whose actions may threaten safety (conflict). Staff act to avert or minimise harm (containment). The Safewards model enabled the identification of ten interventions to reduce the frequency of both. To test the efficacy of these interventions. A pragmatic cluster randomised controlled trial with psychiatric hospitals and wards as the units of randomisation. The main outcomes were rates of conflict and containment. Staff and patients in 31 randomly chosen wards at 15 randomly chosen hospitals. For shifts with conflict or containment incidents, the experimental condition reduced the rate of conflict events by 15% (95% CI 5.7-23.7%) [corrected] relative to the control intervention. The rate of containment events for the experimental intervention was reduced by 23.2% (95% CI 9.9-35.5%). [corrected] Simple interventions aiming to improve staff relationships with patients can reduce the frequency of conflict and containment. IRSCTN38001825. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  8. Structured risk assessment and violence in acute psychiatric wards: randomised controlled trial.

    PubMed

    Abderhalden, Christoph; Needham, Ian; Dassen, Theo; Halfens, Ruud; Haug, Hans-Joachim; Fischer, Joachim E

    2008-07-01

    There is a lack of research on the possible contribution of a structured risk assessment to the reduction of aggression in psychiatric in-patient care. To assess whether such risk assessments decrease the incidence of violence and coercion. A cluster randomised controlled trial was conducted with 14 acute psychiatric admission wards as the units of randomisation, including a preference arm. The intervention comprised a standardised risk assessment following admission with mandatory evaluation of prevention in high-risk patients. Incidence rates decreased substantially in the intervention wards, whereas little change occurred in the control wards. The adjusted risk ratios suggest a 41% reduction in severe aggressive incidents and a 27% decline in the use of coercive measures. The severity of aggressive incidents did not decrease. Structured risk assessment during the first days of treatment may contribute to reduced violence and coercion in acute psychiatric wards.

  9. A complex intervention to improve pregnancy outcome in obese women; the UPBEAT randomised controlled trial.

    PubMed

    Briley, Annette L; Barr, Suzanne; Badger, Shirlene; Bell, Ruth; Croker, Helen; Godfrey, Keith M; Holmes, Bridget; Kinnunen, Tarja I; Nelson, Scott M; Oteng-Ntim, Eugene; Patel, Nashita; Robson, Stephen C; Sandall, Jane; Sanders, Thomas; Sattar, Naveed; Seed, Paul T; Wardle, Jane; Poston, Lucilla

    2014-02-18

    Despite the widespread recognition that obesity in pregnant women is associated with adverse outcomes for mother and child, there is no intervention proven to reduce the risk of these complications. The primary aim of this randomised controlled trial is to assess in obese pregnant women, whether a complex behavioural intervention, based on changing diet (to foods with a lower glycemic index) and physical activity, will reduce the risk of gestational diabetes (GDM) and delivery of a large for gestational age (LGA) infant. A secondary aim is to determine whether the intervention lowers the long term risk of obesity in the offspring. Multicentre randomised controlled trial comparing a behavioural intervention designed to improve glycemic control with standard antenatal care in obese pregnant women.Inclusion criteria; women with a BMI ≥30 kg/m2 and a singleton pregnancy between 15+0 weeks and 18+6 weeks' gestation. Exclusion criteria; pre-defined, pre-existing diseases and multiple pregnancy. Randomisation is on-line by a computer generated programme and is minimised by BMI category, maternal age, ethnicity, parity and centre. Intervention; this is delivered by a health trainer over 8 sessions. Based on control theory, with elements of social cognitive theory, the intervention is designed to improve maternal glycemic control. Women randomised to the control arm receive standard antenatal care until delivery according to local guidelines. All women have a 75 g oral glucose tolerance test at 27+0- 28+6 weeks' gestation.Primary outcome; Maternal: diagnosis of GDM, according to the International Association of Diabetes in Pregnancy Study Group (IADPSG) criteria. Neonatal; infant LGA defined as >90th customised birth weight centile.Sample size; 1546 women to provide 80% power to detect a 25% reduction in the incidence of GDM and a 30% reduction in infants large for gestational age. All aspects of this protocol have been evaluated in a pilot randomised controlled trial

  10. A complex intervention to improve pregnancy outcome in obese women; the UPBEAT randomised controlled trial

    PubMed Central

    2014-01-01

    Background Despite the widespread recognition that obesity in pregnant women is associated with adverse outcomes for mother and child, there is no intervention proven to reduce the risk of these complications. The primary aim of this randomised controlled trial is to assess in obese pregnant women, whether a complex behavioural intervention, based on changing diet (to foods with a lower glycemic index) and physical activity, will reduce the risk of gestational diabetes (GDM) and delivery of a large for gestational age (LGA) infant. A secondary aim is to determine whether the intervention lowers the long term risk of obesity in the offspring. Methods/Design Multicentre randomised controlled trial comparing a behavioural intervention designed to improve glycemic control with standard antenatal care in obese pregnant women. Inclusion criteria; women with a BMI ≥30 kg/m2 and a singleton pregnancy between 15+0 weeks and 18+6 weeks’ gestation. Exclusion criteria; pre-defined, pre-existing diseases and multiple pregnancy. Randomisation is on-line by a computer generated programme and is minimised by BMI category, maternal age, ethnicity, parity and centre. Intervention; this is delivered by a health trainer over 8 sessions. Based on control theory, with elements of social cognitive theory, the intervention is designed to improve maternal glycemic control. Women randomised to the control arm receive standard antenatal care until delivery according to local guidelines. All women have a 75 g oral glucose tolerance test at 27+0- 28+6 weeks’ gestation. Primary outcome; Maternal: diagnosis of GDM, according to the International Association of Diabetes in Pregnancy Study Group (IADPSG) criteria. Neonatal; infant LGA defined as >90th customised birth weight centile. Sample size; 1546 women to provide 80% power to detect a 25% reduction in the incidence of GDM and a 30% reduction in infants large for gestational age. Discussion All aspects of this protocol have been

  11. Robust ?dynamic output feedback control of networked control systems with congestion control

    NASA Astrophysics Data System (ADS)

    Rasool, Faiz; Kiong Ngaung, Sing

    2015-07-01

    This paper investigates a robust ?dynamic output feedback controller for networked control systems (NCSs) with a simple congestion control scheme. This scheme enables the NCSs design to enjoy advantages of both time-triggered and event-triggered systems. The proposed scheme compares current measurement with last transmitted measurement. If difference between them is less than a prescribed percentage of the current measurements then no measurement is transmitted to controller and the controller always uses the last transmitted measurements to calculate feedback gains. Moreover, this technique is applied to controller output as well. The stability criteria for closed-loop system is formulated using the Lyapunov-Krasovskii functional approach. The sufficient conditions for the controller are given in terms of solvability of bilinear matrix inequalities (BMIs). These BMIs are converted into quasi-convex linear matrix inequalities that are solved using the cone complementarity linearisation algorithm. A simulation example is used to evaluate how effective the simple congestion control scheme is in reducing network bandwidth.

  12. Robust H∞VIBRATION Control for Flexible Linkage Mechanism Systems with Piezoelectric Sensors and Actuators

    NASA Astrophysics Data System (ADS)

    ZHANG, X.; SHAO, C.; LI, S.; XU, D.; ERDMAN, A. G.

    2001-05-01

    It is well known that the unmodelled dynamics may deteriorate the efficiency of a controller if the controller is not robust enough. This paper presents a robust H∞vibration control method for high-speed flexible linkage mechanism systems with piezoelectric actuators and sensors. The robust H∞controller is designed based on the complex mode and the H∞control theory. The numerical simulation shows that the vibration can be significantly suppressed with permitted actuator voltages by the controller. The robustH∞ controller can avoid the spillover due to mode truncation to compare with some other method.

  13. A randomised controlled trial of Silirum vaccine for control of paratuberculosis in farmed red deer.

    PubMed

    Stringer, L A; Wilson, P R; Heuer, C; Mackintosh, C G

    2013-12-07

    A randomised controlled trial to assess the efficacy of Silirum vaccine in control of paratuberculosis in young farmed deer was carried out in 2008-2009 in six New Zealand herds with a history of clinical disease. Vaccination with Silirum was carried out in four-month-old deer, and vaccinates (n=1671) and controls (n=1664) were weighed at vaccination and at 8 and 12 months old, when faecal samples were collected from 125 vaccinates and 123 controls on five farms. Deer were slaughtered between 11 and 20 months of age, and the incidence of gross visceral lymph node (VLN) pathology typical of paratuberculosis in deer, that is, enlarged and/or granulomatous VLN, was recorded. Clinical disease was confirmed in 18 controls and seven vaccinates, representing a vaccine efficacy estimate of 60 per cent (95% CI 3 per cent to 83 per cent, P=0.04). Forty-seven percent (95% CI 38 per cent to 56 per cent) of faecal samples from vaccinates and 55 per cent (95% CI 46 per cent to 64 per cent) from controls were Mycobacterium avium subspecies paratuberculosis positive (P=0.5). Average daily liveweight gain did not differ between the cohorts. At slaughter, 1.4 per cent of vaccinates and 4.5 per cent of controls had VLN pathology, RR=0.32 (95% CI 0.19 to 0.54, P<0.001). These data indicate that vaccination with Silirum may be useful as an aid to control losses associated with clinical paratuberculosis in young deer.

  14. 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

  15. 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

  16. 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.

  17. Calculating the probability of random sampling for continuous variables in submitted or published randomised controlled trials.

    PubMed

    Carlisle, J B; Dexter, F; Pandit, J J; Shafer, S L; Yentis, S M

    2015-07-01

    In a previous paper, one of the authors (JBC) used a chi-squared method to analyse the means (SD) of baseline variables, such as height or weight, from randomised controlled trials by Fujii et al., concluding that the probabilities that the reported distributions arose by chance were infinitesimally small. Subsequent testing of that chi-squared method, using simulation, suggested that the method was incorrect. This paper corrects the chi-squared method and tests its performance and the performance of Monte Carlo simulations and ANOVA to analyse the probability of random sampling. The corrected chi-squared method and ANOVA method became inaccurate when applied to means that were reported imprecisely. Monte Carlo simulations confirmed that baseline data from 158 randomised controlled trials by Fujii et al. were different to those from 329 trials published by other authors and that the distribution of Fujii et al.'s data were different to the expected distribution, both p < 10(-16) . The number of Fujii randomised controlled trials with unlikely distributions was less with Monte Carlo simulation than with the 2012 chi-squared method: 102 vs 117 trials with p < 0.05; 60 vs 86 for p < 0.01; 30 vs 56 for p < 0.001; and 12 vs 24 for p < 0.00001, respectively. The Monte Carlo analysis nevertheless confirmed the original conclusion that the distribution of the data presented by Fujii et al. was extremely unlikely to have arisen from observed data. The Monte Carlo analysis may be an appropriate screening tool to check for non-random (i.e. unreliable) data in randomised controlled trials submitted to journals. © 2015 The Association of Anaesthetists of Great Britain and Ireland.

  18. Randomised controlled trial of topical kanuka honey for the treatment of acne.

    PubMed

    Semprini, Alex; Braithwaite, Irene; Corin, Andrew; Sheahan, Davitt; Tofield, Christopher; Helm, Colin; Montgomery, Barney; Fingleton, James; Weatherall, Mark; Beasley, Richard

    2016-02-01

    To investigate the efficacy of Honevo, a topical 90% medical-grade kanuka honey, and 10% glycerine (honey product) as a treatment for facial acne. Randomised controlled trial with single blind assessment of primary outcome variable. Outpatient primary care from 3 New Zealand localities. Of 136 participants aged between 16 and 40 years with a diagnosis of acne and baseline Investigator's Global Assessment (IGA) for acne score of ≥ 2.68, participants were randomised to each treatment arm. All participants applied Protex, a triclocarban-based antibacterial soap twice daily for 12 weeks. Participants randomised to the honey product treatment arm applied this directly after washing off the antibacterial soap, twice daily for 12 weeks. The primary outcome was ≥ 2 point decrease in IGA score from baseline at 12 weeks. Secondary outcomes included mean lesion counts and changes in subject-rated acne improvement and severity at weeks 4 and 12, and withdrawals for worsening acne. 4/53 (7.6%) participants in the honey product group and 1/53 (1.9%) of participants in the control group had a ≥ 2 improvement in IGA score at week 12, compared with baseline, OR (95% CI) for improvement 4.2 (0.5 to 39.3), p=0.17. There were 15 and 14 participants who withdrew from the honey product group and control group, respectively. This randomised controlled trial did not find evidence that addition of medical-grade kanuka honey in combination with 10% glycerine to standard antibacterial soap treatment is more effective than the use of antibacterial soap alone in the treatment of acne. ACTRN12614000003673; 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/

  19. Randomised controlled trial of topical kanuka honey for the treatment of acne

    PubMed Central

    Semprini, Alex; Corin, Andrew; Sheahan, Davitt; Tofield, Christopher; Helm, Colin; Montgomery, Barney; Fingleton, James; Weatherall, Mark; Beasley, Richard

    2016-01-01

    Objective To investigate the efficacy of Honevo, a topical 90% medical-grade kanuka honey, and 10% glycerine (honey product) as a treatment for facial acne. Design Randomised controlled trial with single blind assessment of primary outcome variable. Setting Outpatient primary care from 3 New Zealand localities. Participants Of 136 participants aged between 16 and 40 years with a diagnosis of acne and baseline Investigator's Global Assessment (IGA) for acne score of ≥2.68, participants were randomised to each treatment arm. Interventions All participants applied Protex, a triclocarban-based antibacterial soap twice daily for 12 weeks. Participants randomised to the honey product treatment arm applied this directly after washing off the antibacterial soap, twice daily for 12 weeks. Outcome measures The primary outcome was ≥2 point decrease in IGA score from baseline at 12 weeks. Secondary outcomes included mean lesion counts and changes in subject-rated acne improvement and severity at weeks 4 and 12, and withdrawals for worsening acne. Results 4/53 (7.6%) participants in the honey product group and 1/53 (1.9%) of participants in the control group had a ≥ 2 improvement in IGA score at week 12, compared with baseline, OR (95% CI) for improvement 4.2 (0.5 to 39.3), p=0.17. There were 15 and 14 participants who withdrew from the honey product group and control group, respectively. Conclusions This randomised controlled trial did not find evidence that addition of medical-grade kanuka honey in combination with 10% glycerine to standard antibacterial soap treatment is more effective than the use of antibacterial soap alone in the treatment of acne. Trial registration number ACTRN12614000003673; Results. PMID:26832428

  20. 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.

  1. 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

  2. Maximising the impact of qualitative research in feasibility studies for randomised controlled trials: guidance for researchers.

    PubMed

    O'Cathain, Alicia; Hoddinott, Pat; Lewin, Simon; Thomas, Kate J; Young, Bridget; Adamson, Joy; Jansen, Yvonne Jfm; Mills, Nicola; Moore, Graham; Donovan, Jenny L

    2015-01-01

    Feasibility studies are increasingly undertaken in preparation for randomised controlled trials in order to explore uncertainties and enable trialists to optimise the intervention or the conduct of the trial. Qualitative research can be used to examine and address key uncertainties prior to a full trial. We present guidance that researchers, research funders and reviewers may wish to consider when assessing or undertaking qualitative research within feasibility studies for randomised controlled trials. The guidance consists of 16 items within five domains: research questions, data collection, analysis, teamwork and reporting. Appropriate and well conducted qualitative research can make an important contribution to feasibility studies for randomised controlled trials. This guidance may help researchers to consider the full range of contributions that qualitative research can make in relation to their particular trial. The guidance may also help researchers and others to reflect on the utility of such qualitative research in practice, so that trial teams can decide when and how best to use these approaches in future studies.

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

    PubMed Central

    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

    2016-01-01

    Objectives 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. Design A single-centre, unblinded, cluster feasibility randomised controlled trial examining Social Stories delivered within a school environment compared with an attentional control. Setting 37 primary schools in York, UK. Participants 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). Outcome measures Acceptability and feasibility of the trial, intervention and of measurements required to assess outcomes in a definitive trial. Results 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. Conclusions 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. Trial registration number ISRCTN96286707; Results. PMID:27515756

  4. The Diabetes Care Project: an Australian multicentre, cluster randomised controlled trial [study protocol

    PubMed Central

    2013-01-01

    Background Diabetes mellitus is an increasingly prevalent metabolic disorder that is associated with substantial disease burden. Australia has an opportunity to improve ways of caring for the growing number of people with diabetes, but this may require changes to the way care is funded, organised and delivered. To inform how best to care for people with diabetes, and to identify the extent of change that is required to achieve this, the Diabetes Care Project (DCP) will evaluate the impact of two different, evidence-based models of care (compared to usual care) on clinical quality, patient and provider experience, and cost. Methods/Design The DCP uses a pragmatic, cluster randomised controlled trial design. Accredited general practices that are situated within any of the seven Australian Medicare Locals/Divisions of General Practice that have agreed to take part in the study were invited to participate. Consenting practices will be randomly assigned to one of three treatment groups for approximately 18 to 22 months: (a) control group (usual care); (b) Intervention 1 (which tests improvements that could be made within the current funding model, facilitated through the use of an online chronic disease management network); or (c) Intervention 2 (which includes the same components as Intervention 1, as well as altered funding to support voluntary patient registration with their practice, incentive payments and a care facilitator). Adult patients who attend the enrolled practices and have established (≥12 month’s duration) type 1 diabetes mellitus or newly diagnosed or established type 2 diabetes mellitus are invited to participate. Multiple outcomes will be studied, including changes in glycosylated haemoglobin (primary outcome), changes in other biochemical and clinical metrics, incidence of diabetes-related complications, quality of life, clinical depression, success of tailored care, patient and practitioner satisfaction, and budget sustainability. Discussion

  5. The Diabetes Care Project: an Australian multicentre, cluster randomised controlled trial [study protocol].

    PubMed

    Leach, Matthew J; Segal, Leonie; Esterman, Adrian; Armour, Caroline; McDermott, Robyn; Fountaine, Tim

    2013-12-20

    Diabetes mellitus is an increasingly prevalent metabolic disorder that is associated with substantial disease burden. Australia has an opportunity to improve ways of caring for the growing number of people with diabetes, but this may require changes to the way care is funded, organised and delivered. To inform how best to care for people with diabetes, and to identify the extent of change that is required to achieve this, the Diabetes Care Project (DCP) will evaluate the impact of two different, evidence-based models of care (compared to usual care) on clinical quality, patient and provider experience, and cost. The DCP uses a pragmatic, cluster randomised controlled trial design. Accredited general practices that are situated within any of the seven Australian Medicare Locals/Divisions of General Practice that have agreed to take part in the study were invited to participate. Consenting practices will be randomly assigned to one of three treatment groups for approximately 18 to 22 months: (a) control group (usual care); (b) Intervention 1 (which tests improvements that could be made within the current funding model, facilitated through the use of an online chronic disease management network); or (c) Intervention 2 (which includes the same components as Intervention 1, as well as altered funding to support voluntary patient registration with their practice, incentive payments and a care facilitator). Adult patients who attend the enrolled practices and have established (≥12 month's duration) type 1 diabetes mellitus or newly diagnosed or established type 2 diabetes mellitus are invited to participate. Multiple outcomes will be studied, including changes in glycosylated haemoglobin (primary outcome), changes in other biochemical and clinical metrics, incidence of diabetes-related complications, quality of life, clinical depression, success of tailored care, patient and practitioner satisfaction, and budget sustainability. This project responds to a need for robust

  6. Designing a robust minimum variance controller using discrete slide mode controller approach.

    PubMed

    Alipouri, Yousef; Poshtan, Javad

    2013-03-01

    Designing minimum variance controllers (MVC) for nonlinear systems is confronted with many difficulties. The methods able to identify MIMO nonlinear systems are scarce. Harsh control signals produced by MVC are among other disadvantages of this controller. Besides, MVC is not a robust controller. In this article, the Vector ARX (VARX) model is used for simultaneously modeling the system and disturbance in order to tackle these disadvantages. For ensuring the robustness of the control loop, the discrete slide mode controller design approach is used in designing MVC and generalized MVC (GMVC). The proposed method for controller design is tested on a nonlinear experimental Four-Tank benchmark process and is compared with nonlinear MVCs designed by neural networks. In spite of the simplicity of designing GMVCs for the VARX models with uncertainty, the results show that the proposed method is accurate and implementable.

  7. 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

  8. 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.

  9. Homoeopathy for delayed onset muscle soreness: a randomised double blind placebo controlled trial.

    PubMed Central

    Vickers, A J; Fisher, P; Smith, C; Wyllie, S E; Lewith, G T

    1997-01-01

    OBJECTIVE: To pilot a model for determining whether a homoeopathic medicine is superior to placebo for delayed onset muscle soreness (DOMS). DESIGN: Randomised double blind placebo controlled trial. SETTING: Physiotherapy department of a homoeopathic hospital. SUBJECTS: Sixty eight healthy volunteers (average age 30; 41% men) undertook a 10 minute period of bench stepping carrying a small weight and were randomised to a homoeopathic medicine or placebo. OUTCOME MEASURES: Mean muscle soreness in the five day period after the exercise test, symptom free days, maximum soreness score, days to no soreness, days on medication. RESULTS: The difference between group means was 0.17 in favour of placebo with 95% confidence intervals +/- 0.50. Similar results were found for other outcome measures. CONCLUSION: The study did not find benefit of the homoeopathic remedy in DOMS. Bench stepping may not be an appropriate model to evaluate the effects of a treatment on DOMS because of wide variation between subject soreness scores. PMID:9429007

  10. Group art therapy as an adjunctive treatment for people with schizophrenia: a randomised controlled trial (MATISSE).

    PubMed

    Crawford, M J; Killaspy, H; Barnes, T R; Barrett, B; Byford, S; Clayton, K; Dinsmore, J; Floyd, S; Hoadley, A; Johnson, T; Kalaitzaki, E; King, M; Leurent, B; Maratos, A; O'Neill, F A; Osborn, D; Patterson, S; Soteriou, T; Tyrer, P; Waller, D

    2012-01-01

    To examine the clinical effectiveness and cost-effectiveness of referral to group art therapy plus standard care, compared with referral to an activity group plus standard care and standard care alone, among people with schizophrenia. A three-arm, parallel group, single-blind, pragmatic, randomised controlled trial. Participants were randomised via an independent and remote telephone randomisation service using permuted blocks, stratified by study centre. Study participants were recruited from secondary care mental health and social services in four UK centres. Potential participants were aged 18 years or over, had a clinical diagnosis of schizophrenia, confirmed by an examination of case notes, and provided written informed consent. We excluded those who were unable to speak sufficient English to complete the baseline assessment, those with severe cognitive impairment and those already receiving arts therapy. Group art therapy was delivered by registered art therapists according to nationally agreed standards. Groups had up to eight members, lasted for 90 minutes and ran for 12 months. Members were given access to a range of art materials and encouraged to use these to express themselves freely. Activity groups were designed to control for the non-specific effects of group art therapy. Group facilitators offered various activities and encouraged participants to collectively select those they wanted to pursue. Standard care involved follow-up from secondary care mental health services and the option of referral to other services, except arts therapies, as required. Our co-primary outcomes were global functioning (measured using the Global Assessment of Functioning Scale - GAF) and mental health symptoms (measured using the Positive and Negative Syndrome Scale - PANSS) at 24 months. The main secondary outcomes were level of group attendance, social functioning, well-being, health-related quality of life, service utilisation and other costs measured 12 and 24 months

  11. 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.

  12. 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.

  13. Corticosteroids in acute traumatic brain injury: systematic review of randomised controlled trials.

    PubMed Central

    Alderson, P.; Roberts, I.

    1997-01-01

    OBJECTIVE: To quantify the effectiveness and safety of corticosteroids in the treatment of acute traumatic brain injury. DESIGN: Systematic review of randomised controlled trials of corticosteroids in acute traumatic brain injury. Summary odds ratios were estimated as an inverse variance weighted average of the odds ratios for each study. SETTING: Randomised trials available by March 1996. SUBJECTS: The included trials with outcome data comprised 2073 randomised participants. RESULTS: The effect of corticosteroids on the risk of death was reported in 13 included trials. The pooled odds ratio for the 13 trials was 0.91 (95% confidence interval 0.74 to 1.12). Pooled absolute risk reduction was 1.8% (-2.5% to 5.7%). For the 10 trials that reported death or disability the pooled odds ratio was 0.90 (0.72 to 1.11). For infections of any type the pooled odds ratio was 0.92 (0.69 to 1.23) and for the seven trials reporting gastrointestinal bleeding it was 1.05 (0.44 to 2.52). With only those trials with the best quality of concealment of allocation, the pooled odds ratio estimates for death and death or disability became closer to unity. CONCLUSIONS: This systematic review of randomised controlled trials of corticosteroids in acute traumatic brain injury shows that there remains considerable uncertainty over their effects. Neither moderate benefits nor moderate harmful effects can be excluded. The widely practicable nature of the drugs and the importance of the health problem suggest that large simple trials are feasible and worth while to establish whether there are any benefits from use of corticosteroids in this setting. PMID:9224126

  14. 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.

  15. 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.

  16. Robust stability and performance of time-delay control systems.

    PubMed

    Keviczky, L; Bányász, Cs

    2007-04-01

    Most of the optimal and adaptive regulators assume an a priori known time delay. The time-delay mismatch can cause unwanted instability. Influence of this uncertainty is investigated in connection with the required performance and robustness.

  17. Robustness and Actuator Bandwidth of MRP-Based Sliding Mode Control for Spacecraft Attitude Control Problems

    NASA Astrophysics Data System (ADS)

    Keum, Jung-Hoon; Ra, Sung-Woong

    2009-12-01

    Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.

  18. Robustness, flexibility, and sensitivity in a multifunctional motor control model.

    PubMed

    Lyttle, David N; Gill, Jeffrey P; Shaw, Kendrick M; Thomas, Peter J; Chiel, Hillel J

    2017-02-01

    Motor systems must adapt to perturbations and changing conditions both within and outside the body. We refer to the ability of a system to maintain performance despite perturbations as "robustness," and the ability of a system to deploy alternative strategies that improve fitness as "flexibility." Different classes of pattern-generating circuits yield dynamics with differential sensitivities to perturbations and parameter variation. Depending on the task and the type of perturbation, high sensitivity can either facilitate or hinder robustness and flexibility. Here we explore the role of multiple coexisting oscillatory modes and sensory feedback in allowing multiphasic motor pattern generation to be both robust and flexible. As a concrete example, we focus on a nominal neuromechanical model of triphasic motor patterns in the feeding apparatus of the marine mollusk Aplysia californica. We find that the model can operate within two distinct oscillatory modes and that the system exhibits bistability between the two. In the "heteroclinic mode," higher sensitivity makes the system more robust to changing mechanical loads, but less robust to internal parameter variations. In the "limit cycle mode," lower sensitivity makes the system more robust to changes in internal parameter values, but less robust to changes in mechanical load. Finally, we show that overall performance on a variable feeding task is improved when the system can flexibly transition between oscillatory modes in response to the changing demands of the task. Thus, our results suggest that the interplay of sensory feedback and multiple oscillatory modes can allow motor systems to be both robust and flexible in a variable environment.

  19. Robust control of linear ceramic motor drive with LLCC resonant technique.

    PubMed

    Wai, Rong-Jong

    2003-07-01

    This study presents a robust control system for a linear ceramic motor (LCM) that is driven by a high-frequency voltage source inverter using two-inductance two-capacitance (LLCC) resonant technique. The structure and driving principle of the LCM are introduced. Because the dynamic characteristics and motor parameters of the LCM are nonlinear and time varying, a robust control system is designed based on the hypothetical dynamic model to achieve high-precision position control. The presentation of robust control for the LCM drive system is divided into three parts, which comprise state feedback controller, feed-forward controller, and uncertainty controller. The adaptation laws of control gains in the robust control system are derived in the sense of Lyapunov stability theorem such that the stability of the control system can be guaranteed. It not only has the learning ability similar to intelligent control, but also its control framework is more simple than intelligent control. With the proposed robust control system, the controlled LCM drive possesses the advantages of good tracking control performance and robustness to uncertainties. The effectiveness of the proposed robust control system is verified by experimental results in the presence of uncertainties. In addition, the advantages of the proposed control system are indicated in comparison with the traditional integral-proportional (IP) position control system.

  20. 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.

  1. Components of placebo effect: randomised controlled trial in patients with irritable bowel syndrome

    PubMed Central

    2008-01-01

    Objective To investigate whether placebo effects can experimentally be separated into the response to three components—assessment and observation, a therapeutic ritual (placebo treatment), and a supportive patient-practitioner relationship—and then progressively combined to produce incremental clinical improvement in patients with irritable bowel syndrome. To assess the relative magnitude of these components. Design A six week single blind three arm randomised controlled trial. Setting Academic medical centre. Participants 262 adults (76% women), mean (SD) age 39 (14), diagnosed by Rome II criteria for and with a score of ≥150 on the symptom severity scale. Interventions For three weeks either waiting list (observation), placebo acupuncture alone (“limited”), or placebo acupuncture with a patient-practitioner relationship augmented by warmth, attention, and confidence (“augmented”). At three weeks, half of the patients were randomly assigned to continue in their originally assigned group for an additional three weeks. Main outcome measures Global improvement scale (range 1-7), adequate relief of symptoms, symptom severity score, and quality of life. Results At three weeks, scores on the global improvement scale were 3.8 (SD 1.0) v 4.3 (SD 1.4) v 5.0 (SD 1.3) for waiting list versus “limited” versus “augmented,” respectively (P<0.001 for trend). The proportion of patients reporting adequate relief showed a similar pattern: 28% on waiting list, 44% in limited group, and 62% in augmented group (P<0.001 for trend). The same trend in response existed in symptom severity score (30 (63) v 42 (67) v 82 (89), P<0.001) and quality of life (3.6 (8.1) v 4.1 (9.4) v 9.3 (14.0), P<0.001). All pairwise comparisons between augmented and limited patient-practitioner relationship were significant: global improvement scale (P<0.001), adequate relief of symptoms (P<0.001), symptom severity score (P=0.007), quality of life (P=0.01).Results were similar at six week

  2. Robustness of controlling edge dynamics in complex networks against node failure.

    PubMed

    Pang, Shao-Peng; Hao, Fei; Wang, Wen-Xu

    2016-11-01

    The robustness of controlling complex networks is significant in network science. In this paper, we focus on evaluating and analyzing the robustness of controlling edge dynamics in complex networks against node failure. Using three categories of all nodes to quantify the robustness, we find that the percentages of the three types of nodes are mainly related to the degree distribution of networks. The simulation results of model networks and analytic calculations show that the sparse inhomogeneous networks, which emerge in many real complex networks, have strong control robustness from the point of the number of ordinary nodes, but the strong positive correlation between in and out degrees reduces the control robustness. Evaluation of real-world networks indicates that most of them have few or no critical nodes, that is, they do not need to increase driver nodes to maintain control for most of node failures. Then an adding circuit-link strategy is proposed to optimize the robustness of edge controllability.

  3. Farm practices to control E. coli O157 in young cattle--a randomised controlled trial.

    PubMed

    Ellis-Iversen, Johanne; Smith, Richard P; Van Winden, Steven; Paiba, Giles A; Watson, Eamon; Snow, Lucy C; Cook, Alasdair J C

    2008-01-01

    A randomised controlled trial was used to investigate the effect of three complex management intervention packages to reduce the burden of E. coli O157 in groups of young-stock on cattle farms in England and Wales. All intervention farms were assigned measures to avoid buying in new animals and having direct contact or sharing water sources with other cattle. Furthermore, package A (7 farms) aimed to keep a clean environment and closed groups of young-stock; package B (14 farms) aimed for improved water and feed hygiene, whilst package C was assigned both A and B. The control farms (26 farms) were asked not to alter their practices. Farms, which were assigned intervention package A, exhibited a 48% reduction in E. coli O157 burden over the 4.5 months (average) of observation, compared to 18% on the control farms. The effect of package A compared to the control farms in a crude intention-to-treat model was RR = 0.26 (p=0.122). When the risk ratio was adjusted for actual application of the different measures, the effect of intervention package A became stronger and statistically significant (RR = 0.14 p=0.032). Statistical evidence (p< 0.05) showed that dry bedding and maintaining animals in the same groups were the most important measures within the package and weak evidence (p< 0.1) showed that a closed herd policy and no contact with other cattle may also be of importance. Compliance with the other measures in package A had no influence on the effect of the package. No evidence of effect of the other two intervention packages was found.

  4. Modified intention to treat reporting in randomised controlled trials: systematic review.

    PubMed

    Abraha, Iosief; Montedori, Alessandro

    2010-06-14

    To determine the incidence and characteristics of randomised controlled trials that report using the modified intention to treat approach, and how the approach is described. Systematic review. PubMed, Embase, Cochrane central register of controlled trials, ISI Web of Knowledge, Ovid, HighWire Press, Science-Direct, Ingenta, Medscape, BioMed Central, Springer, and Wiley, from inception to December 2006. Incidence of trials in which use of modified intention to treat was reported, and how the approach was described (classified according to the type and number of deviations from the intention to treat approach). 475 randomised controlled trials reported use of a modified intention to treat analysis. Of these, 76 (16%) were published in five highly cited general medical journals. The incidence of all trials that reported use of modified intention to treat published in journals indexed in Medline increased from 0.006% in 1982-6 to 0.5% in 2002-6 (P<0.001 for linear trend). When the description of the modified intention to treat was examined in each trial, 192 (40%) reported one type of deviation from the intention to treat approach, 261 (55%) reported two or more types, and 22 (5%) did not describe any type. In 266 (56%) of the trials the deviation was related to the treatment received, in 196 (41%) to a post baseline assessment, in 118 (25%) to a baseline assessment, in 108 (23%) to a target condition, and in 23 (5%) to follow-up. Post-randomisation exclusions occurred in 380 (80%) trials. The results reported by 270 of the 352 (77%) superiority trials favoured the drug under investigation. All of the 123 trials using equivalence or non-inferiority methods to investigate interventions reported results that favoured their assumptions. Randomised controlled trials that report using a modified intention to treat are increasingly being published in the medical literature. The descriptions of such an approach were ambiguous, and may cover any type of descriptions for

  5. 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.

  6. 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.

  7. 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.

  8. Analysis and synthesis of HVDC controls for robust stability of power systems

    SciTech Connect

    Venkataraman, S.; Khammash, M.H.; Vittal, V.

    1995-11-01

    High Voltage DC (HVDC) links have controllable characteristics with potential for affecting system stability. This paper follows the robustness methodology procedure to analyze the stability robustness of HVDC controls in power systems over a range of operating conditions. A novel method to design power system controllers using the robustness methodology is also proposed. Numerical results for a sample test-system are obtained and compared with those obtained by conventional techniques.

  9. 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

  10. A self-management programme for COPD: a randomised controlled trial.

    PubMed

    Mitchell, Katy E; Johnson-Warrington, Vicki; Apps, Lindsay D; Bankart, John; Sewell, Louise; Williams, Johanna E; Rees, Karen; Jolly, Kate; Steiner, Michael; Morgan, Mike; Singh, Sally J

    2014-12-01

    Studies of programmes of self-management support for chronic obstructive pulmonary disease (COPD) have been inconclusive. The Self-Management Programme of Activity, Coping and Education (SPACE) FOR COPD is a 6-week self-management intervention for COPD, and this study aimed to evaluate the effectiveness of this intervention in primary care. A single-blind randomised controlled trial recruited people with COPD from primary care and randomised participants to receive usual care or SPACE FOR COPD. Outcome measures were performed at baseline, 6 weeks and 6 months. The primary outcome was symptom burden, measured by the self-reported Chronic Respiratory Questionnaire (CRQ-SR) dyspnoea domain. Secondary outcomes included other domains of the CRQ-SR, shuttle walking tests, disease knowledge, anxiety, depression, self-efficacy, smoking status and healthcare utilisation. 184 people with COPD were recruited and randomised. At 6 weeks, there were significant differences between groups in CRQ-SR dyspnoea, fatigue and emotion scores, exercise performance, anxiety, and disease knowledge. At 6 months, there was no between-group difference in change in CRQ-SR dyspnoea. Exercise performance, anxiety and smoking status were significantly different between groups at 6 months, in favour of the intervention. This brief self-management intervention did not improve dyspnoea over and above usual care at 6 months; however, there were gains in anxiety, exercise performance, and disease knowledge. ©ERS 2014.

  11. Pragmatic randomised controlled trial of group psychoeducation versus group support in the maintenance of bipolar disorder.

    PubMed

    Morriss, Richard K; Lobban, Fiona; Jones, Steven; Riste, Lisa; Peters, Sarah; Roberts, Christopher; Davies, Linda; Mayes, Debbie

    2011-07-21

    Non-didactically delivered curriculum based group psychoeducation has been shown to be more effective than both group support in a specialist mood disorder centre in Spain (with effects lasting up to five years), and treatment as usual in Australia. It is unclear whether the specific content and form of group psychoeducation is effective or the chance to meet and work collaboratively with other peers. The main objective of this trial is to determine whether curriculum based group psychoeducation is more clinically and cost effective than unstructured peer group support. Single blind two centre cluster randomised controlled trial of 21 sessions group psychoeducation versus 21 sessions group peer support in adults with bipolar 1 or 2 disorder, not in current episode but relapsed in the previous two years. Individual randomisation is to either group at each site. The groups are carefully matched for the number and type of therapists, length and frequency of the interventions and overall aim of the groups but differ in content and style of delivery. The primary outcome is time to next bipolar episode with measures of the therapeutic process, barriers and drivers to the effective delivery of the interventions and economic analysis. Follow up is for 96 weeks after randomisation. The trial has features of both an efficacy and an effectiveness trial design. For generalisability in England it is set in routine public mental health practice with a high degree of expert patient involvement.

  12. 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).

  13. Early versus delayed oxytocin augmentation in nulliparous women with prolonged labour--a randomised controlled trial.

    PubMed

    Dencker, A; Berg, M; Bergqvist, L; Ladfors, L; Thorsén, L S; Lilja, H

    2009-03-01

    To study the effects of early versus delayed oxytocin augmentation on the obstetrical and neonatal outcome in nulliparous women with spontaneous but prolonged labour. Randomised controlled study. Two delivery units in Sweden. Healthy nulliparous women with normal pregnancies, spontaneous onset of active labour, a cervical dilatation of 4-9 cm and no progress in cervical dilatation for 2 hours and for an additional hour if amniotomy was performed due to slow progress. Women (n = 630) were randomly allocated either to labour augmentation by oxytocin infusion (early oxytocin group) or to postponement of oxytocin augmentation for another 3 hours (expectant group). Mode of delivery (spontaneous vaginal or instrumental vaginal delivery or caesarean section) and time from randomisation to delivery. The caesarean section rate was 29 of 314 (9%) in the early oxytocin group and 34 of 316 (11%) in the expectant group (OR 0.8, 95% CI 0.5-1.4), and instrumental vaginal delivery 54 of 314 (17%) in the early oxytocin versus 38 of 316 (12%) in the expectant group (OR 1.5, 95% CI 0.97-2.4). Early initiation of oxytocin resulted in a mean decrease of 85 minutes in the randomisation to delivery interval. Early administration of oxytocin did not change the rate of caesarean section or instrumental vaginal delivery but shortened labour duration significantly in women with a 2-hour arrest in cervical dilatation. No other clear benefits or harms were seen between early and delayed administration of oxytocin.

  14. Clinical efficacy of oral alendronate in ankylosing spondylitis: a randomised placebo-controlled trial.

    PubMed

    Coates, Lucy; Packham, Jonathan C; Creamer, Paul; Hailwood, Sarah; Bhalla, Ashley S; Chakravarty, Kuntal; Mulherin, Diamuid; Taylor, Gordon; Mattey, Derek L; Bhalla, Ashok K

    2017-01-01

    A prospective, double blind, randomised, placebo controlled trial over 2 years was performed to test the efficacy of alendronate, an oral aminobisphosphonate, in improving symptoms and arrest disease progression in patients with mild to severe ankylosing spondylitis (AS). 180 patients with AS were randomised to receive weekly alendronate 70 mg or placebo (1:1 randomisation). BAS-G was the primary outcome measure with Bath indices as secondary outcomes. Vertebral x-rays were performed at 0 and 24 months. Biomarkers (including CRP, IL-1beta, IL6, VEGF, MMP-1, and MMP-3) were collected during the first 12 months. There was no significant difference between the placebo and treatment groups in any of the recorded outcomes over the 2 years including clinical indices, biomarkers, and radiology. The change in BAS-G, the primary outcome measure, was -0.21 for the treatment group and -0.42 for the placebo group p=0.57. Change in all other clinical outcome measures were also non-significant; BASDAI p=0.86, BASFI p=0.37, BASMI p=0.021. Sub-group analysis of those subjects with a baseline BASDAI >4 were also non-significant. This prospective study demonstrates that alendronate 70mg weekly for 2 years was no more efficacious than placebo in improving clinical or laboratory measures of disease activity or measures of physical impact in subjects with mild to severe active AS. ID SRCTN12308164, registered on 15.12.2015.

  15. 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.

  16. The CRASH trial: the first large-scale, randomised, controlled trial in head injury

    PubMed Central

    Roberts, Ian

    2001-01-01

    The global epidemic of head injuries is just beginning. Many are caused by road traffic crashes. It is estimated that, by 2020, road traffic crashes will have moved from its present position of ninth to third in the world disease burden ranking, as measured in disability adjusted life years. In developing countries, it will have moved to second. The Corticosteroid Randomisation After Significant Head Injury (CRASH) trial is a large-scale, randomised, controlled trial, among adults with head injury and impaired consciousness, of the effects of a short-term infusion of corticosteroids on death and on neurological disability. Following a successful pilot phase, which included over 1000 randomised participants, the main phase of the trial is now underway. Over the next 5 years, the trial aims to recruit a total of 20,000 patients. Such large numbers will only be possible if hundreds of doctors and nurses can collaborate in emergency departments all over the world. The trial is currently recruiting, and new collaborators are welcome to join the trial (see ). PMID:11737908

  17. 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

  18. The Internet for weight control in an obese sample: results of a randomised controlled trial

    PubMed Central

    McConnon, Áine; Kirk, Sara FL; Cockroft, Jennie E; Harvey, Emma L; Greenwood, Darren C; Thomas, James D; Ransley, Joan K; Bojke, Laura

    2007-01-01

    Background Rising levels of obesity coupled with the limited success of currently available weight control methods highlight the need for investigation of novel approaches to obesity treatment. This study aims to determine the effectiveness and cost-effectiveness of an Internet-based resource for obesity management. Methods A randomised controlled trial conducted in a community setting, where obese volunteers (n = 221) were randomly assigned to Internet group (n = 111) or usual care group (n = 110). Objective measures of weight and height were obtained. Questionnaires were used to collect dietary, lifestyle, physical activity and quality of life data. Data were collected at baseline, six months and 12 months. Results Data were collected on 54 (49%) participants in the Internet group and 77 (70%) participants in the usual care group at 12 months. Based on analysis conducted on all available data, the Internet group lost 1.3 kg, compared with 1.9 kg weight loss in the usual care group at 12 months, a non-significant difference (difference = 0.6 kg; 95% CI: -1.4 to 2.5, p = 0.56). No significant differences in change in secondary outcome measures between the two groups at six or 12 months were revealed. Total costs per person per year were higher in the Internet group than the usual care group (£992.40 compared to £276.12), primarily due to the fixed costs associated with setting up the website, and QALYs were similar (0.78 and 0.77) for both groups. Conclusion This trial failed to show any additional benefit of this website in terms of weight loss or secondary outcome measures compared with usual care. High attrition and low compliance limits the results of this research. The results suggest that the Internet-based weight control resource was not a cost-effective tool for weight loss in the obese sample studied. Trail Registration ISRCTN 58621669 PMID:18093289

  19. Dry needling and exercise for chronic whiplash - a randomised controlled trial.

    PubMed

    Sterling, Michele; Valentin, Stephanie; Vicenzino, Bill; Souvlis, Tina; Connelly, Luke B

    2009-12-18

    Chronic whiplash is a common and costly problem. Sensory hypersensitivity is a feature of chronic whiplash that is associated with poor responsiveness to physical treatments such as exercise. Modalities such as dry-needling have shown some capacity to modulate sensory hypersensitivity, suggesting that when combined with advice and exercise, such an approach may be more effective in the management of chronic whiplash. The primary aim of this project is to investigate the effectiveness of dry-needling, advice and exercise for chronic whiplash. A double-blind randomised controlled trial will be conducted. 120 participants with chronic whiplash, grade II will be randomised to receive either 1) dry-needling, advice and exercise or 2) sham dry-needling, advice and exercise. All participants will receive an educational booklet on whiplash. Participants who are randomised to Group 1 will receive 6 treatments of combined dry-needling and exercise delivered in the first 3 weeks of the 6 week program, and 4 treatments of exercise only in the last 3 weeks of the program. Participants randomised to Group 2 will receive an identical protocol, except that a sham dry-needling technique will be used instead of dry-needling. The primary outcome measures are the Neck Disability Index (NDI) and participants' perceived recovery. Outcomes will be measured at 6, 12, 24 and 52 weeks after randomization by an assessor who is blind to the group allocation of the participants. In parallel, an economic analysis will be conducted. This trial will utilise high quality trial methodologies in accordance with CONSORT guidelines. The successful completion of this trial will provide evidence of the effectiveness and cost-effectiveness of a combined treatment approach for the management of chronic whiplash. ACTRN12609000470291.

  20. Study protocol for a randomised controlled trial of invasive versus conservative management of primary spontaneous pneumothorax

    PubMed Central

    Brown, Simon G A; Ball, Emma L; Perrin, Kyle; Read, Catherine A; Asha, Stephen E; Beasley, Richard; Egerton-Warburton, Diana; Jones, Peter G; Keijzers, Gerben; Kinnear, Frances B; Kwan, Ben C H; Lee, Y C Gary; Smith, Julian A; Summers, Quentin A; Simpson, Graham

    2016-01-01

    Introduction Current management of primary spontaneous pneumothorax (PSP) is variable, with little evidence from randomised controlled trials to guide treatment. Guidelines emphasise intervention in many patients, which involves chest drain insertion, hospital admission and occasionally surgery. However, there is evidence that conservative management may be effective and safe, and it may also reduce the risk of recurrence. Significant questions remain regarding the optimal initial approach to the management of PSP. Methods and analysis This multicentre, prospective, randomised, open label, parallel group, non-inferiority study will randomise 342 participants with a first large PSP to conservative or interventional management. To maintain allocation concealment, randomisation will be performed in real time by computer and stratified by study site. Conservative management will involve a period of observation prior to discharge, with intervention for worsening symptoms or physiological instability. Interventional treatment will involve insertion of a small bore drain. If drainage continues after 1 hour, the patient will be admitted. If drainage stops, the drain will be clamped for 4 hours. The patient will be discharged if the lung remains inflated. Otherwise, the patient will be admitted. The primary end point is the proportion of participants with complete lung re-expansion by 8 weeks. Secondary end points are as follows: days in hospital, persistent air leak, predefined complications and adverse events, time to resolution of symptoms, and pneumothorax recurrence during a follow-up period of at least 1 year. The study has 95% power to detect an absolute non-inferiority margin of 9%, assuming 99% successful expansion at 8 weeks in the invasive treatment arm. The primary analysis will be by intention to treat. Ethics and dissemination Local ethics approval has been obtained for all sites. Study findings will be disseminated by publication in a high

  1. A randomised controlled trial. Shifting boundaries of doctors and physiotherapists in orthopaedic outpatient departments

    PubMed Central

    Daker-White, G.; Carr, A. J.; Harvey, I.; Woolhead, G.; Bannister, G.; Nelson, I.; Kammerling, M.

    1999-01-01

    OBJECTIVE: To evaluate the effectiveness and cost effectiveness of specially trained physiotherapists in the assessment and management of defined referrals to hospital orthopaedic departments. DESIGN: Randomised controlled trial. SETTING: Orthopaedic outpatient departments in two hospitals. SUBJECTS: 481 patients with musculoskeletal problems referred for specialist orthopaedic opinion. INTERVENTIONS: Initial assessment and management undertaken by post- Fellowship junior orthopaedic surgeons, or by specially trained physiotherapists working in an extended role (orthopaedic physiotherapy specialists). MAIN OUTCOME MEASURES: Patient centred measures of pain, functional disability and perceived handicap. RESULTS: A total of 654 patients were eligible to join the trial, 481 (73.6%) gave their consent to be randomised. The two arms (doctor n = 244, physiotherapist n = 237) were similar at baseline. Baseline and follow up questionnaires were completed by 383 patients (79.6%). The mean time to follow up was 5.6 months after randomisation, with similar distributions of intervals to follow up in both arms. The only outcome for which there was a statistically or clinically important difference between arms was in a measure of patient satisfaction, which favoured the physiotherapist arm. A cost minimisation analysis showed no significant differences in direct costs to the patient or NHS primary care costs. Direct hospital costs were lower (p < 0.00001) in the physiotherapist arm (mean cost per patient = 256 Pounds, n = 232), as they were less likely to order radiographs and to refer patients for orthopaedic surgery than were the junior doctors (mean cost per patient in arm = 498 Pounds, n = 238). CONCLUSIONS: On the basis of the patient centred outcomes measured in this randomised trial, orthopaedic physiotherapy specialists are as effective as post-Fellowship junior staff and clinical assistant orthopaedic surgeons in the initial assessment and management of new referrals

  2. A modular robust control framework for control of movement elicited by multi-electrode intraspinal microstimulation

    NASA Astrophysics Data System (ADS)

    Roshani, Amir; Erfanian, Abbas

    2016-08-01

    Objective. An important issue in restoring motor function through intraspinal microstimulation (ISMS) is the motor control. To provide a physiologically plausible motor control using ISMS, it should be able to control the individual motor unit which is the lowest functional unit of motor control. By focal stimulation only a small group of motor neurons (MNs) within a motor pool can be activated. Different groups of MNs within a motor pool can potentially be activated without involving adjacent motor pools by local stimulation of different parts of a motor pool via microelectrode array implanted into a motor pool. However, since the system has multiple inputs with single output during multi-electrode ISMS, it poses a challenge to movement control. In this paper, we proposed a modular robust control strategy for movement control, whereas multi-electrode array is implanted into each motor activation pool of a muscle. Approach. The controller was based on the combination of proportional-integral-derivative and adaptive fuzzy sliding mode control. The global stability of the controller was guaranteed. Main results. The results of the experiments on rat models showed that the multi-electrode control can provide a more robust control and accurate tracking performance than a single-electrode control. The control output can be pulse amplitude (pulse amplitude modulation, PAM) or pulse width (pulse width modulation, PWM) of the stimulation signal. The results demonstrated that the controller with PAM provided faster convergence rate and better tracking performance than the controller with PWM. Significance. This work represents a promising control approach to the restoring motor functions using ISMS. The proposed controller requires no prior knowledge about the dynamics of the system to be controlled and no offline learning phase. The proposed control design is modular in the sense that each motor pool has an independent controller and each controller is able to control ISMS

  3. 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

  4. 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.

  5. The Women's international study of long-duration oestrogen after menopause (WISDOM): a randomised controlled trial

    PubMed Central

    Vickers, Madge R; Martin, Jeannett; Meade, Tom W

    2007-01-01

    Background At the time of feasibility work and final design of the trial there was no randomised control trial evidence for the long-term risks and benefits of hormone replacement therapy. Observational studies had suggested that long term use of estrogen was likely to be associated, amongst other things, with reduced risks of osteoporosis and ischaemic heart disease and increased risks of breast and endometrial cancer. Concomitant use of progestogens had been shown to protect against endometrial cancer, but there were few data showing how progestogen might affect estrogen actions on other conditions. Disease specific risks from observational studies suggested that, overall, long-term HRT was likely to be beneficial. Several studies showed that mortality from all causes was lower in HRT users than in non-users. Some secondary cardiovascular prevention trials were ongoing but evidence was also required for a range of outcomes in healthy women. The WISDOM trial was designed to compare combined estrogen and progestogen versus placebo, and estrogen alone versus combined estrogen and progestogen. During the development of WISDOM the Women's Health Initiative trial was designed, funded and started in the US. Design Randomised, placebo, controlled, trial. Methods The trial was set in general practices in the UK (384), Australia (94), and New Zealand (24). In these practices 284175 women aged 50–69 years were registered with 226282 potentially eligible. We sought to randomise 22300 postmenopausal women aged 50 – 69 and treat for ten years. The interventions were: conjugated equine estrogens, 0.625 mg orally daily; conjugated equine estrogens plus medroxyprogesterone acetate 2.5/5.0 mg orally daily; matched placebo. Primary outcome measures were: major cardiovascular disease, osteoporotic fractures, breast cancer and dementia. Secondary outcomes were: other cancers, all cause death, venous thromboembolism and cerebro-vascular disease. Results The trial was prematurely

  6. 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

  7. Effectiveness of financial incentives to improve adherence to maintenance treatment with antipsychotics: cluster randomised controlled trial

    PubMed Central

    Yeeles, Ksenija; Bremner, Stephen; Lauber, Christoph; Eldridge, Sandra; Ashby, Deborah; David, Anthony S; O’Connell, Nicola; Forrest, Alexandra; Burns, Tom

    2013-01-01

    Objective To test whether offering financial incentives to patients with psychotic disorders is effective in improving adherence to maintenance treatment with antipsychotics. Design Cluster randomised controlled trial. Setting Community mental health teams in secondary psychiatric care in the United Kingdom. Participants Patients with a diagnosis of schizophrenia, schizoaffective disorder, or bipolar disorder, who were prescribed long acting antipsychotic (depot) injections but had received 75% or less of the prescribed injections. We randomly allocated 73 teams with a total of 141 patients. Primary outcome data were available for 35 intervention teams with 75 patients (96% of randomised) and for 31 control teams with 56 patients (89% of randomised). Interventions Participants in the intervention group were offered £15 (€17; $22) for each depot injection over a 12 month period. Participants in the control condition received treatment as usual. Main outcome measure The primary outcome was the percentage of prescribed depot injections given during the 12 month intervention period. Results 73 teams with 141 consenting patients were randomised, and outcomes were assessed for 131 patients (93%). Average baseline adherence was 69% in the intervention group and 67% in the control group. During the 12 month trial period adherence was 85% in the intervention group and 71% in the control group. The adjusted effect estimate was 11.5% (95% confidence interval 3.9% to 19.0%, P=0.003). A secondary outcome was an adherence of ≥95%, which was achieved in 28% of the intervention group and 5% of the control group (adjusted odds ratio 8.21, 95% confidence interval 2.00 to 33.67, P=0.003). Although differences in clinician rated clinical improvement between the groups failed to reach statistical significance, patients in the intervention group had more favourable subjective quality of life ratings (β=0.71, 95% confidence interval 0.26 to 1.15, P=0.002). The number of admissions

  8. Sahaja yoga in the management of moderate to severe asthma: a randomised controlled trial

    PubMed Central

    Manocha, R; Marks, G; Kenchington, P; Peters, D; Salome, C

    2002-01-01

    Background: Sahaja Yoga is a traditional system of meditation based on yogic principles which may be used for therapeutic purposes. A study was undertaken to assess the effectiveness of this therapy as an adjunctive tool in the management of asthma in adult patients who remained symptomatic on moderate to high doses of inhaled steroids. Methods: A parallel group, double blind, randomised controlled trial was conducted. Subjects were randomly allocated to Sahaja yoga and control intervention groups. Both the yoga and the control interventions required the subjects to attend a 2 hour session once a week for 4 months. Asthma related quality of life (AQLQ, range 0–4), Profile of Mood States (POMS), level of airway hyperresponsiveness to methacholine (AHR), and a diary card based combined asthma score (CAS, range 0–12) reflecting symptoms, bronchodilator usage, and peak expiratory flow rates were measured at the end of the treatment period and again 2 months later. Results: Twenty one of 30 subjects randomised to the yoga intervention and 26 of 29 subjects randomised to the control group were available for assessment at the end of treatment. The improvement in AHR at the end of treatment was 1.5 doubling doses (95% confidence interval (CI) 0.0 to 2.9, p=0.047) greater in the yoga intervention group than in the control group. Differences in AQLQ score (0.41, 95% CI –0.04 to 0.86) and CAS (0.9, 95% CI –0.9 to 2.7) were not significant (p>0.05). The AQLQ mood subscale did improve more in the yoga group than in the control group (difference 0.63, 95% CI 0.06 to 1.20), as did the summary POMS score (difference 18.4, 95% CI 0.2 to 36.5, p=0.05). There were no significant differences between the two groups at the 2 month follow up assessment. Conclusions: This randomised controlled trial has shown that the practice of Sahaja yoga does have limited beneficial effects on some objective and subjective measures of the impact of asthma. Further work is required to

  9. Designing a robust PID congestion controller supporting TCP flows based on H optimal control theory

    NASA Astrophysics Data System (ADS)

    Yu, Li; Shi, Zibo; Chen, Kun; Shu, Yantai

    2007-09-01

    A robust PID controller for active queue management (AQM) based on modern H∞ optimal control theory is presented in this paper. Taken both robustness and closed loop performance into consideration, most desirable parameters value can be gotten through some straightforward analytical formulas. Our robust PID controller is determined only by one parameter, other than traditional PID controller is by three or more. Additionally, this new parameters determining method can not only be extended to other AQM controller based on classical control theory or optimal control theory, but also be easily understood and implementation. We evaluate the performances of the controller extensively. The results show that the robust PID congestion controller outperform the existing controller, such as PI, RED, on keeping the router queue size at the target value. The most obvious property of the controller is that it takes on robustness such that it can adapt the network dynamic.

  10. 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.

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

    PubMed

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

    2017-09-06

    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.

  12. 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.

  13. Nonlinear robust control of proton exchange membrane fuel cell by state feedback exact linearization

    NASA Astrophysics Data System (ADS)

    Li, Q.; Chen, W.; Wang, Y.; Jia, J.; Han, M.

    By utilizing the state feedback exact linearization approach, a nonlinear robust control strategy is designed based on a multiple-input multiple-output (MIMO) dynamic nonlinear model of proton exchange membrane fuel cell (PEMFC). The state feedback exact linearization approach can achieve the global exact linearization via the nonlinear coordinate transformation and the dynamic extension algorithm such that H ∞ robust control strategy can be directly utilized to guarantee the robustness of the system. The proposed dynamic nonlinear model is tested by comparing the simulation results with the experimental data in Fuel Cell Application Centre in Temasek Polytechnic. The comprehensive results of simulation manifest that the dynamic nonlinear model with nonlinear robust control law has better transient and robust stability when the vehicle running process is simulated. The proposed nonlinear robust controller will be very useful to protect the membrane damage by keeping the pressure deviations as small as possible during large disturbances and prolong the stack life of PEMFC.

  14. 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.

  15. 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

  16. Physical activity for cancer survivors: meta-analysis of randomised controlled trials

    PubMed Central

    Fong, Daniel Y T; Hui, Bryant P H; Lee, Antoinette M; Macfarlane, Duncan J; Leung, Sharron S K; Cerin, Ester; Chan, Wynnie Y Y; Leung, Ivy P F; Taylor, Aliki J; Cheng, Kar-keung

    2012-01-01

    Objective To systematically evaluate the effects of physical activity in adult patients after completion of main treatment related to cancer. Design Meta-analysis of randomised controlled trials with data extraction and quality assessment performed independently by two researchers. Data sources Pubmed, CINAHL, and Google Scholar from the earliest possible year to September 2011. References from meta-analyses and reviews. Study selection Randomised controlled trials that assessed the effects of physical activity in adults who had completed their main cancer treatment, except hormonal treatment. Results There were 34 randomised controlled trials, of which 22 (65%) focused on patients with breast cancer, and 48 outcomes in our meta-analysis. Twenty two studies assessed aerobic exercise, and four also included resistance or strength training. The median duration of physical activity was 13 weeks (range 3-60 weeks). Most control groups were considered sedentary or were assigned no exercise. Based on studies on patients with breast cancer, physical activity was associated with improvements in insulin-like growth factor-I, bench press, leg press, fatigue, depression, and quality of life. When we combined studies on different types of cancer, we found significant improvements in body mass index (BMI), body weight, peak oxygen consumption, peak power output, distance walked in six minutes, right handgrip strength, and quality of life. Sources of study heterogeneity included age, study quality, study size, and type and duration of physical activity. Publication bias did not alter our conclusions. Conclusions Physical activity has positive effects on physiology, body composition, physical functions, psychological outcomes, and quality of life in patients after treatment for breast cancer. When patients with cancer other than breast cancer were also included, physical activity was associated with reduced BMI and body weight, increased peak oxygen consumption and peak power

  17. 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.

  18. 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

  19. 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.

  20. A randomised controlled feasibility trial of alcohol consumption and the ability to appropriately use a firearm.

    PubMed

    Carr, B G; Wiebe, D J; Richmond, T S; Cheney, R; Branas, C C

    2009-12-01

    To show the feasibility of using a controlled trial to investigate the effect of alcohol on firearm use. Randomised, blinded, placebo-controlled trial in the Firearm Usage and Safety Experiments (FUSE) Lab. Treatment subjects (male, 21-40-year-old, non-habitual drinkers, with no professional firearms training) received alcohol; control subjects received placebo alcohol. The AIS PRISim Firearm Simulator, including real pistols retrofitted to discharge compressed air cartridges that simulate firearm recoil and sound, was used to measure firearm performance. Accuracy and speed for target shooting, reaction time scenarios, and scenarios requiring judgement about when to use a gun were measured. 12 subjects enrolled in the trial, completing 160 training scenarios. All subjects in the alcohol arm reached target alcohol level. 33% of placebo subjects reported alcohol consumption. Mechanical malfunction of the simulator occurred in 9 of 160 (5.6%) scenarios. Intoxicated subjects were less accurate, slower to fire in reaction time scenarios, and quicker to fire in scenarios requiring judgement relative to controls. The feasibility of a randomised, controlled trial exploring the relationship between alcohol consumption and firearm use was shown. The hypothesis that alcohol consumption worsens accuracy and retards judgement about when to use a gun should be tested. Larger trials could inform policies regarding firearm use while intoxicated.

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

    PubMed

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

    2013-06-01

    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. 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. 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). 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.

  2. The application of cost averaging techniques to robust control of the benchmark problem

    NASA Technical Reports Server (NTRS)

    Hagood, Nesbitt W.; Crawley, Edward F.

    1991-01-01

    A method is presented for the synthesis of robust controllers for linear time invariant systems with parameterized uncertainty structures. The method involves minimizing the average quadratic (H2) cost over the parameterized system. Bonded average cost implies stability over the set of systems. The average cost functional is minimized to derive robust fixed-order dynamic compensators. The robustness properties of these controllers are demonstrated on the sample problem.

  3. Robust Control for the Segway with Unknown Control Coefficient and Model Uncertainties

    PubMed Central

    Kim, Byung Woo; Park, Bong Seok

    2016-01-01

    The Segway, which is a popular vehicle nowadays, is an uncertain nonlinear system and has an unknown time-varying control coefficient. Thus, we should consider the unknown time-varying control coefficient and model uncertainties to design the controller. Motivated by this observation, we propose a robust control for the Segway with unknown control coefficient and model uncertainties. To deal with the time-varying unknown control coefficient, we employ the Nussbaum gain technique. We introduce an auxiliary variable to solve the underactuated problem. Due to the prescribed performance control technique, the proposed controller does not require the adaptive technique, neural network, and fuzzy logic to compensate the uncertainties. Therefore, it can be simple. From the Lyapunov stability theory, we prove that all signals in the closed-loop system are bounded. Finally, we provide the simulation results to demonstrate the effectiveness of the proposed control scheme. PMID:27367696

  4. Robust Control for the Segway with Unknown Control Coefficient and Model Uncertainties.

    PubMed

    Kim, Byung Woo; Park, Bong Seok

    2016-06-29

    The Segway, which is a popular vehicle nowadays, is an uncertain nonlinear system and has an unknown time-varying control coefficient. Thus, we should consider the unknown time-varying control coefficient and model uncertainties to design the controller. Motivated by this observation, we propose a robust control for the Segway with unknown control coefficient and model uncertainties. To deal with the time-varying unknown control coefficient, we employ the Nussbaum gain technique. We introduce an auxiliary variable to solve the underactuated problem. Due to the prescribed performance control technique, the proposed controller does not require the adaptive technique, neural network, and fuzzy logic to compensate the uncertainties. Therefore, it can be simple. From the Lyapunov stability theory, we prove that all signals in the closed-loop system are bounded. Finally, we provide the simulation results to demonstrate the effectiveness of the proposed control scheme.

  5. Study protocol for a randomised controlled trial of electronic cigarettes versus nicotine patch for smoking cessation

    PubMed Central

    2013-01-01

    Background Electronic cigarettes (e-cigarettes or electronic nicotine delivery systems [ENDS]) are electrically powered devices generally similar in appearance to a cigarette that deliver a propylene glycol and/or glycerol mist to the airway of users when drawing on the mouthpiece. Nicotine and other substances such as flavourings may be included in the fluid vaporised by the device. People report using e-cigarettes to help quit smoking and studies of their effects on tobacco withdrawal and craving suggest good potential as smoking cessation aids. However, to date there have been no adequately powered randomised trials investigating their cessation efficacy or safety. This paper outlines the protocol for this study. Methods/design Design: Parallel group, 3-arm, randomised controlled trial. Participants: People aged ≥18 years resident in Auckland, New Zealand (NZ) who want to quit smoking. Intervention: Stratified blocked randomisation to allocate participants to either Elusion™ e-cigarettes with nicotine cartridges (16 mg) or with placebo cartridges (i.e. no nicotine), or to nicotine patch (21 mg) alone. Participants randomised to the e-cigarette groups will be told to use them ad libitum for one week before and 12 weeks after quit day, while participants randomised to patches will be told to use them daily for the same period. All participants will be offered behavioural support to quit from the NZ Quitline. Primary outcome: Biochemically verified (exhaled carbon monoxide) continuous abstinence at six months after quit day. Sample size: 657 people (292 in both the nicotine e-cigarette and nicotine patch groups and 73 in the placebo e-cigarettes group) will provide 80% power at p = 0.05 to detect an absolute difference of 10% in abstinence between the nicotine e-cigarette and nicotine patch groups, and 15% between the nicotine and placebo e-cigarette groups. Discussion This trial will inform international debate and policy on the regulation and

  6. 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.

  7. 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.

  8. 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

  9. Integrated multidisciplinary diagnostic approach for dementia care: randomised controlled trial.

    PubMed

    Wolfs, Claire A G; Kessels, Alfons; Dirksen, Carmen D; Severens, Johan L; Verhey, Frans R J

    2008-04-01

    An integrated multidisciplinary approach to dementia is often recommended but has rarely been evaluated. To evaluate the clinical effects of an integrated multidisciplinary diagnostic facility for psychogeriatric patients. Patients suspected of having complex psychogeriatric problems were randomly allocated to the intervention (n=137) or to treatment as usual (n=93). They were assessed at baseline, and at 6 months and 12 months follow-up by means of personal interviews with the patient's proxy. The primary outcome was health-related quality of life, assessed using the visual analogue scale (VAS) of the EuroQd measure, EQ-5D. Health-related quality of life had improved at 6 months in the intervention group, whereas that of the control group had decreased. Furthermore, more patients in the intervention group experienced a clinically relevant improvement of 10 points or more on the VAS at both follow-up measurements. An integrated multidisciplinary approach improves dementia care.

  10. 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

  11. The informed consent process in randomised controlled trials: a nurse-led process.

    PubMed

    Cresswell, Pip; Gilmour, Jean

    2014-03-01

    Clinical trials are carried out with human participants to answer questions about the best way to diagnose, treat and prevent illness. Participants must give informed consent to take part in clinical trials that requires understanding of how clinical trials work and their purpose. Randomised controlled trials provide strong evidence but their complex design is difficult for both clinicians and participants to understand. Increasingly, ensuring informed consent in randomised controlled trials has become part of the clinical research nurse role. The aim of this study was to explore in depth the clinical research nurse role in the informed consent process using a qualitative descriptive approach. Three clinical research nurses were interviewed and data analysed using a thematic analysis approach. Three themes were identified to describe the process of ensuring informed consent. The first theme, Preparatory partnerships, canvassed the relationships required prior to initiation of the informed consent process. The second theme, Partnering the participant, emphasises the need for ensuring voluntariness and understanding, along with patient advocacy. The third theme, Partnership with the project, highlights the clinical research nurse contribution to the capacity of the trial to answer the research question through appropriate recruiting and follow up of participants. Gaining informed consent in randomised controlled trials was complex and required multiple partnerships. A wide variety of skills was used to protect the safety of trial participants and promote quality research. The information from this study contributes to a greater understanding of the clinical research nurse role, and suggests the informed consent process in trials can be a nurse-led one. In order to gain collegial, employer and industry recognition it is important this aspect of the nursing role is acknowledged.

  12. Long-term lifestyle changes after colorectal cancer screening: randomised controlled trial.

    PubMed

    Berstad, Paula; Løberg, Magnus; Larsen, Inger Kristin; Kalager, Mette; Holme, Øyvind; Botteri, Edoardo; Bretthauer, Michael; Hoff, Geir

    2015-08-01

    There is uncertainty whether cancer screening affects participant incentives for favourable lifestyle. The present study investigates long-term effects of colorectal cancer (CRC) screening on lifestyle changes. In 1999-2001, men and women drawn from the population registry were randomised to screening for CRC by flexible sigmoidoscopy ('invited-to-screening' arm) or to no-screening (control arm) in the Norwegian Colorectal Cancer Prevention trial. A subgroup of 3043 individuals in the 'invited-to-screening' and 2819 in the control arm, aged 50-55 years, randomised during 2001 had their lifestyle assessed by a questionnaire at inclusion and after 11 years (42% of cohort). The outcome was 11-year changes in lifestyle factors (body weight, smoking status, physical exercise, selected dietary habits) and in total lifestyle score (0-4 points, translating to the number of lifestyle recommendations adhered to). We compared outcomes in the two randomisation arms and attendees with positive versus negative findings. Total lifestyle scores improved in both arms. The improvement was smaller in the 'invited-to-screening' arm (score 1.43 at inclusion; 1.58 after 11 years) compared with the control arm (score 1.49 at inclusion; 1.67 after 11 years); adjusted difference -0.05 (95% CI -0.09 to -0.01; p=0.03). The change in the score was less favourable in screening attendees with a positive compared with negative screening result; adjusted difference -0.16 (95% CI -0.25 to -0.08; p<0.001). The present study suggests that possible unfavourable lifestyle changes after CRC screening are modest. Lifestyle counselling may be considered as part of cancer screening programmes. NCT00119912. 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.

  13. Single dose vitamin A treatment in acute shigellosis in Bangladesh children: randomised double blind controlled trial.

    PubMed Central

    Hossain, S.; Biswas, R.; Kabir, I.; Sarker, S.; Dibley, M.; Fuchs, G.; Mahalanabis, D.

    1998-01-01

    OBJECTIVE: To evaluate the efficacy of a single large oral dose of vitamin A in treating acute shigellosis in children in Bangladesh. DESIGN: Randomised double blind controlled clinical trial. SETTING: Dhaka Hospital, International Centre for Diarrhoeal Disease Research, Bangladesh. SUBJECTS: 83 children aged 1-7 years with bacteriologically proved shigellosis but no clinical signs of vitamin A deficiency; 42 were randomised to treatment with vitamin A and 41 formed a control group. INTERVENTION: Children were given a single oral dose of 200,000 IU of vitamin A plus 25 IU vitamin E or a control preparation of 25 IU vitamin E. MAIN OUTCOME MEASURES: Clinical cure on study day 5 and bacteriological cure. RESULTS: Baseline characteristics of the subjects in the two treatment groups were similar. Significantly more children in the vitamin A group than in the control group achieved clinical cure (19/42 (45%) v 8/14 (20%); chi 2 = 5.14, 1 df, P = 0.02; risk ratio = 0.68 (95% confidence interval; 0.50 to 0.93)). When cure was determined bacteriologically, the groups had similar rates (16/42 (38%) v 16/41 (39%); chi 2 = 0.02, 1 df, P = 0.89; risk ratio = 0.98 (0.70 to 1.39)). CONCLUSIONS: Vitamin A reduces the severity of acute shigellosis in children living in areas where vitamin A deficiency is a major public health problem. PMID:9492664

  14. A prospective randomised controlled trial of capnography vs. bronchoscopy for Blue Rhino percutaneous tracheostomy.

    PubMed

    Mallick, A; Venkatanath, D; Elliot, S C; Hollins, T; Nanda Kumar, C G

    2003-09-01

    A crucial step for successful percutaneous tracheostomy is the introduction of the needle and guide wire into the trachea. Capnography has recently been proposed as one way to confirm tracheal needle placement. In this randomised controlled study, we used capnography in 26 patients and bronchoscopy in 29 patients to confirm needle placement for percutaneous tracheostomy using Blue Rhino kit. The operating times and the incidence of peri-operative complications were similar for both groups. Capnography proved to be as effective as bronchoscopy in confirming correct needle placement.

  15. ‘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

  16. A randomised controlled trial of benefit finding in caregivers: The Building Resources in Caregivers Study Protocol.

    PubMed

    Brand, Charles; O'Connell, Brenda H; Gallagher, Stephen

    2015-07-01

    Caregivers may engage in benefit finding, that is, an increase in perceived positive growth, as a cognitive strategy for coping with stress. The Building Resources in Caregivers study will compare effects of a brief benefit finding writing intervention with a control intervention. Caregivers of people with mental and physical disabilities will be randomised into either a benefit-writing group or a neutral writing group. Caregivers will complete measures relating to themselves and care-recipients (e.g. sociodemographics and illness type) and psychometric measures of benefit finding, distress and quality of life at three time points. Additionally, qualitative commentary on participation experiences will be gathered.

  17. 1-year follow-up of neurofeedback treatment in adolescents with attention-deficit hyperactivity disorder: randomised controlled trial

    PubMed Central

    Bongers, Ilja L.; Popma, Arne; Janssen, Tieme W.P.; van Nieuwenhuizen, Chijs

    2016-01-01

    Background Estimates of the effectiveness of neurofeedback as a treatment for attention-deficit hyperactivity disorder (ADHD) are mixed. Aims To investigate the long-term additional effects of neurofeedback (NFB) compared with treatment as usual (TAU) for adolescents with ADHD. Method Using a multicentre parallel-randomised controlled trial design, 60 adolescents with a DSM-IV-TR diagnosis of ADHD receiving NFB+TAU (n=41) or TAU (n=19) were followed up. Neurofeedback treatment consisted of approximately 37 sessions of theta/sensorimotor rhythm (SMR)-training on the vertex (Cz). Outcome measures included behavioural self-reports and neurocognitive measures. Allocation to the conditions was unmasked. Results At 1-year follow-up, inattention as reported by adolescents was decreased (range ηp2=0.23–0.36, P<0.01) and performance on neurocognitive tasks was faster (range ηp2=0.20–0.67, P<0.005) irrespective of treatment group. Conclusions Overall, NFB+TAU was as effective as TAU. Given the absence of robust additional effects of neurofeedback in the current study, results do not support the use of theta/SMR neurofeedback as a treatment for adolescents with ADHD and comorbid disorders in clinical practice. Declaration of interest None. Copyright and usage © The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence. PMID:27703763

  18. 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.

  19. Stability of discrete-time networked control systems and its extension for robust H ∞ control

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Han, Chongzhao; Ding, Baocang

    2013-02-01

    The stability of discrete-time Networked Control Systems (NCSs) is studied in this article. By introducing some scalars into matrix cross-term bounding technique, we present a new approach for the state feedback controller, with less conservatism, based on the Bilinear Matrix Inequalities (BMIs) and the descriptor model transformation. We further extend the method to robust H ∞ control considering both disturbances and parametric uncertainties. For the BMI problem which is difficult to be solved directly, a modified optimisation algorithm is proposed. The practicability, less conservatism and effectiveness of the results are demonstrated by two examples.

  20. Intensive Patient Education Improves Glycaemic Control in Diabetes Compared to Conventional Education: A Randomised Controlled Trial in a Nigerian Tertiary Care Hospital

    PubMed Central

    Essien, Okon; Otu, Akaninyene; Umoh, Victor; Enang, Ofem; Hicks, Joseph Paul; Walley, John

    2017-01-01

    Background Diabetes is now a global epidemic, but most cases are now in low- and middle-income countries. Diabetes self-management education (DSME) is key to enabling patients to manage their chronic condition and can reduce the occurrence of costly and devastating complications. However, there is limited evidence on the effectiveness of different DSME programmes in resource limited settings. Methods We conducted an unblinded, parallel-group, individually-randomised controlled trial at the University of Calabar Teaching Hospital (Nigeria) to evaluate whether an intensive and systematic DSME programme, using structured guidelines, improved glycaemic control compared to the existing ad hoc patient education (clinical practice was unchanged). Eligible patients (≥18 years, HbA1c > 8.5% and physically able to participate) were randomly allocated by permuted block randomisation to participate for six months in either an intensive or conventional education group. The primary outcome was HbA1c (%) at six-months. Results We randomised 59 participants to each group and obtained six-month HbA1c outcomes from 53 and 51 participants in the intensive and conventional education groups, respectively. Intensive group participants had a mean six-month HbA1c (%) of 8.4 (95% CI: 8 to 8.9), while participants in the conventional education group had a mean six-month HbA1c (%) of 10.2 (95% CI: 9.8 to 10.7). The difference was statistically (P < 0.0001) and clinically significant, with intensive group participants having HbA1c outcomes on average -1.8 (95% CI: -2.4 to -1.2) percentage points lower than conventional group participants. Results were robust to adjustment for a range of covariates and multiple imputation of missing outcome data. Conclusions This study demonstrates the effectiveness of a structured, guideline-based DSME intervention in a LMIC setting versus a pragmatic comparator. The intervention is potentially replicable at other levels of the Nigerian healthcare system

  1. Intensive Patient Education Improves Glycaemic Control in Diabetes Compared to Conventional Education: A Randomised Controlled Trial in a Nigerian Tertiary Care Hospital.

    PubMed

    Essien, Okon; Otu, Akaninyene; Umoh, Victor; Enang, Ofem; Hicks, Joseph Paul; Walley, John

    2017-01-01

    Diabetes is now a global epidemic, but most cases are now in low- and middle-income countries. Diabetes self-management education (DSME) is key to enabling patients to manage their chronic condition and can reduce the occurrence of costly and devastating complications. However, there is limited evidence on the effectiveness of different DSME programmes in resource limited settings. We conducted an unblinded, parallel-group, individually-randomised controlled trial at the University of Calabar Teaching Hospital (Nigeria) to evaluate whether an intensive and systematic DSME programme, using structured guidelines, improved glycaemic control compared to the existing ad hoc patient education (clinical practice was unchanged). Eligible patients (≥18 years, HbA1c > 8.5% and physically able to participate) were randomly allocated by permuted block randomisation to participate for six months in either an intensive or conventional education group. The primary outcome was HbA1c (%) at six-months. We randomised 59 participants to each group and obtained six-month HbA1c outcomes from 53 and 51 participants in the intensive and conventional education groups, respectively. Intensive group participants had a mean six-month HbA1c (%) of 8.4 (95% CI: 8 to 8.9), while participants in the conventional education group had a mean six-month HbA1c (%) of 10.2 (95% CI: 9.8 to 10.7). The difference was statistically (P < 0.0001) and clinically significant, with intensive group participants having HbA1c outcomes on average -1.8 (95% CI: -2.4 to -1.2) percentage points lower than conventional group participants. Results were robust to adjustment for a range of covariates and multiple imputation of missing outcome data. This study demonstrates the effectiveness of a structured, guideline-based DSME intervention in a LMIC setting versus a pragmatic comparator. The intervention is potentially replicable at other levels of the Nigerian healthcare system and in other LMICs, where nurses

  2. Effectiveness of customised foot orthoses for Achilles tendinopathy: a randomised controlled trial.

    PubMed

    Munteanu, Shannon E; Scott, Lisa A; Bonanno, Daniel R; Landorf, Karl B; Pizzari, Tania; Cook, Jill L; Menz, Hylton B

    2015-08-01

    To evaluate the effectiveness of customised foot orthoses in chronic mid-portion Achilles tendinopathy. This was a participant-blinded, parallel-group randomised controlled trial at a single centre (La Trobe University, Melbourne, Australia). One hundred and forty participants aged 18-55 years with mid-portion Achilles tendinopathy were randomised to receive eccentric calf muscle exercises with either customised foot orthoses (intervention group) or sham foot orthoses (control group). Allocation to intervention was concealed. The Victorian Institute of Sports Assessment-Achilles (VISA-A) questionnaire was completed at baseline, then at 1, 3, 6 and 12 months, with 3 months being the primary end point. Differences between groups were analysed using intention to treat with analysis of covariance. After randomisation into the customised foot orthoses group (n=67) or sham foot orthoses group (n=73), there was 70.7% follow-up of participants at 3 months. There were no significant differences between groups at any time point. At 3 months, the mean (SD) VISA-A score was 82.1 (16.3) and 79.2 (20.0) points for the customised and sham foot orthosis groups, respectively (adjusted mean difference (95% CI)=2.6 (-2.9 to 8.0), p=0.353). There were no clinically meaningful differences between groups in any of the secondary outcome measures. Customised foot orthoses, prescribed according to the protocol in this study, are no more effective than sham foot orthoses for reducing symptoms and improving function in people with mid-portion Achilles tendinopathy undergoing an eccentric calf muscle exercise programme. Australian New Zealand Clinical Trials Registry: number ACTRN12609000829213. 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.

  3. Acupuncture for hot flushes in perimenopausal and postmenopausal women: a randomised, sham-controlled trial.

    PubMed

    Kim, Dong Il; Jeong, Jae Cheol; Kim, Kun Hyung; Rho, Jin Ju; Choi, Min Sun; Yoon, Sang Ho; Choi, Sun-Mi; Kang, Kyung Won; Ahn, Hong Yup; Lee, Myeong Soo

    2011-12-01

    To determine the effect of acupuncture in treating hot flushes in perimenopausal or postmenopausal women. The study was a randomised single-blind sham-controlled clinical trial. Perimenopausal or postmenopausal women with moderate or severe hot flushes were randomised to receive real or sham acupuncture. Both groups underwent a 4-week run-in period before the treatment. The real acupuncture group received 11 acupuncture treatments for 7 weeks, and the control group underwent sham acupuncture on non-acupuncture points during the same period. Both groups were followed for 8 weeks after the end of treatment period. Changes from baseline in the hot flush scores at week 7, measured by multiplying the hot flush frequency and severity, were the primary outcome. Hot flush frequency, severity and menopause-related symptoms measured with the Menopause Rating Scale Questionnaire were regarded as secondary outcomes. 54 participants were randomised into the real acupuncture group (n=27) and the sham acupuncture group (n=27). The mean change in hot flush scores was -6.4±5.2 in the real acupuncture group and -5.6±9.2 in the sham group at week 7 from values at the start of the acupuncture treatment (10.0±8.1 vs 11.7±12.6), respectively (p=0.0810). No serious adverse events were observed during the whole study period. Compared to sham acupuncture, acupuncture failed to show significantly different effects on the hot flush scores but showed partial benefits on the hot flush severity. Further consideration is needed to develop appropriate strategies for distinguishing non-specific effects from observed overall effectiveness of acupuncture for hot flushes. Whether acupuncture has point-specific effects for hot flushes should be also considered in designing future researches.

  4. Randomised, double-blind, placebo-controlled trial of fructo-oligosaccharides in active Crohn's disease.

    PubMed

    Benjamin, Jane L; Hedin, Charlotte R H; Koutsoumpas, Andreas; Ng, Siew C; McCarthy, Neil E; Hart, Ailsa L; Kamm, Michael A; Sanderson, Jeremy D; Knight, Stella C; Forbes, Alastair; Stagg, Andrew J; Whelan, Kevin; Lindsay, James O

    2011-07-01

    The commensal intestinal microbiota drive the inflammation associated with Crohn's disease. However, bacteria such as bifidobacteria and Faecalibacterium prausnitzii appear to be immunoregulatory. In healthy subjects the intestinal microbiota are influenced by prebiotic carbohydrates such as fructo-oligosaccharides (FOS). Preliminary data suggest that FOS increase faecal bifidobacteria, induce immunoregulatory dendritic cell (DC) responses and reduce disease activity in patients with Crohn's disease. To assess the impact of FOS in patients with active Crohn's disease using an adequately powered randomised double-blind placebo-controlled trial with predefined clinical, microbiological and immunological end points. Patients with active Crohn's disease were randomised to 15 g/day FOS or non-prebiotic placebo for 4 weeks. The primary end point was clinical response at week 4 (fall in Crohn's Disease Activity Index of ≥ 70 points) in the intention-to-treat (ITT) population. 103 patients were randomised to receive FOS (n = 54) or placebo (n = 49). More patients receiving FOS (14 (26%) vs 4 (8%); p = 0.018) withdrew before the 4-week end point. There was no significant difference in the number of patients achieving a clinical response between the FOS and placebo groups in the ITT analysis (12 (22%) vs 19 (39%), p = 0.067). Patients receiving FOS had reduced proportions of interleukin (IL)-6-positive lamina propria DC and increased DC staining of IL-10 (p < 0.05) but no change in IL-12p40 production. There were no significant differences in the faecal concentration of bifidobacteria and F prausnitzii between the groups at baseline or after the 4-week intervention. An adequately powered placebo-controlled trial of FOS showed no clinical benefit in patients with active Crohn's disease, despite impacting on DC function. ISRCTN50422530.

  5. Hypotensive effects of hawthorn for patients with diabetes taking prescription drugs: a randomised controlled trial.

    PubMed

    Walker, Ann F; Marakis, Georgios; Simpson, Eleanor; Hope, Jessica L; Robinson, Paul A; Hassanein, Mohamed; Simpson, Hugh C R

    2006-06-01

    Hawthorn (Crataegus laevigata) leaves, flowers and berries are used by herbal practitioners in the UK to treat hypertension in conjunction with prescribed drugs. Small-scale human studies support this approach. To investigate the effects of hawthorn for hypertension in patients with type 2 diabetes taking prescribed drugs. Randomised controlled trial. General practices in Reading, UK. Patients with type 2 diabetes (n = 79) were randomised to daily 1200 mg hawthorn extract (n = 39) or placebo (n = 40) for 16 weeks. At baseline and outcome a wellbeing questionnaire was completed and blood pressure and fasting blood samples taken. A food frequency questionnaire estimated nutrient intake. Hypotensive drugs were used by 71% of the study population with a mean intake of 4.4 hypoglycaemic and/or hypotensive drugs. Fat intake was lower and sugar intake higher than recommendations, and low micronutrient intake was prevalent. There was a significant group difference in mean diastolic blood pressure reductions (P = 0.035): the hawthorn group showed greater reductions (baseline: 85.6 mmHg, 95% confidence interval [CI] = 83.3 to 87.8; outcome: 83.0 mmHg, 95% CI = 80.5 to 85.7) than the placebo group (baseline: 84.5 mmHg, 95% CI = 82 to 87; outcome: 85.0 mmHg, 95% CI = 82.2 to 87.8). There was no group difference in systolic blood pressure reduction from baseline (3.6 and 0.8 mmHg for hawthorn and placebo groups, respectively; P = 0.329). Although mean fat intake met current recommendations, mean sugar intake was higher and there were indications of potential multiple micronutrient deficiencies. No herb-drug interaction was found and minor health complaints were reduced from baseline in both groups. This is the first randomised controlled trial to demonstrate a hypotensive effect of hawthorn in patients with diabetes taking medication.

  6. Hypotensive effects of hawthorn for patients with diabetes taking prescription drugs: a randomised controlled trial

    PubMed Central

    Walker, Ann F; Marakis, Georgios; Simpson, Eleanor; Hope, Jessica L; Robinson, Paul A; Hassanein, Mohamed; Simpson, Hugh CR

    2006-01-01

    Background Hawthorn (Crataegus laevigata) leaves, flowers and berries are used by herbal practitioners in the UK to treat hypertension in conjunction with prescribed drugs. Small-scale human studies support this approach. Aim To investigate the effects of hawthorn for hypertension in patients with type 2 diabetes taking prescribed drugs. Design of study Randomised controlled trial. Setting General practices in Reading, UK. Method Patients with type 2 diabetes (n = 79) were randomised to daily 1200 mg hawthorn extract (n = 39) or placebo (n = 40) for 16 weeks. At baseline and outcome a wellbeing questionnaire was completed and blood pressure and fasting blood samples taken. A food frequency questionnaire estimated nutrient intake. Results Hypotensive drugs were used by 71% of the study population with a mean intake of 4.4 hypoglycaemic and/or hypotensive drugs. Fat intake was lower and sugar intake higher than recommendations, and low micronutrient intake was prevalent. There was a significant group difference in mean diastolic blood pressure reductions (P = 0.035): the hawthorn group showed greater reductions (baseline: 85.6 mmHg, 95% confidence interval [CI] = 83.3 to 87.8; outcome: 83.0 mmHg, 95% CI = 80.5 to 85.7) than the placebo group (baseline: 84.5 mmHg, 95% CI = 82 to 87; outcome: 85.0 mmHg, 95% CI = 82.2 to 87.8). There was no group difference in systolic blood pressure reduction from baseline (3.6 and 0.8 mmHg for hawthorn and placebo groups, respectively; P = 0.329). Although mean fat intake met current recommendations, mean sugar intake was higher and there were indications of potential multiple micronutrient deficiencies. No herb–drug interaction was found and minor health complaints were reduced from baseline in both groups. Conclusions This is the first randomised controlled trial to demonstrate a hypotensive effect of hawthorn in patients with diabetes taking medication. PMID:16762125

  7. Functional MRI-guided microsurgery of intracranial arteriovenous malformations: study protocol for a randomised controlled trial.

    PubMed

    Zhao, Bing; Cao, Yong; Zhao, Yuanli; Wu, Jun; Wang, Shuo

    2014-10-23

    Intracranial arteriovenous malformations (AVMs) are associated with high morbidity and mortality. Modern microsurgery has improved the results of surgical treatment of AVMs; however, the treatment of AVMs, particularly eloquently located AVMs, still carries a high risk. Functional MRI (fMRI) has been reported to be used for the preoperative evaluation of AVMs in small case series. The purpose is to identify the utility and efficacy of fMRI-guided microsurgery of AVMs in a large randomised controlled trial. The study is a prospective, randomised controlled clinical trial. This study will enrol a total of 600 eligible patients. These eligible patients will be randomised to the standard microsurgery group and the fMRI-guided microsurgery group in a 1:1 ratio. Patient baseline characteristics and AVM architecture and characteristics will be described. In the fMRI-guided group, fMRI mapping of an eloquent cortex in all AVMs will be identified. Surgical complications and outcomes at pretreatment, post-treatment, at discharge and at 1-month, 3-month and 6-month follow-up intervals will be analysed using the modified Rankin Scale (mRS). This trial will determine whether fMRI-guided microsurgery could improve outcomes in patients with AVMs and also identify the safety and efficacy of fMRI-guided microsurgery. The study protocol and written informed consent were reviewed and approved by the Institutional Review Board of Beijing Tiantan Hospital Affiliated to Capital Medical University (ky2012-016-02). Study findings will be disseminated in the printed media. ClinicalTrials.gov NCT01758211. 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.

  8. Evidence for non-random sampling in randomised, controlled trials by Yuhji Saitoh.

    PubMed

    Carlisle, J B; Loadsman, J A

    2017-01-01

    A large number of randomised trials authored by Yoshitaka Fujii have been retracted, in part as a consequence of a previous analysis finding a very low probability of random sampling. Dr Yuhji Saitoh co-authored 34 of those trials and he was corresponding author for eight of them. We found a number of additional randomised, controlled trials that included baseline data, with Saitoh as corresponding author, that Fujii did not co-author. We used Monte Carlo simulations to analyse the baseline data from 32 relevant trials in total as well as an outcome (muscle twitch recovery ratios) reported in several. We also compared a series of muscle twitch recovery graphs appearing in a number of Saitoh's publications. The baseline data in 14/32 randomised, controlled trials had p < 0.01, of which seven p values were < 0.001. Eight trials reported four ratios of the time for the return of muscle activity after neuromuscular blockade, the distributions of which were homogeneous: the p values for the observed Q statistics were 0.0055, 0.031, 0.016 and 0.0071. Comparison of graphs revealed multiple coincident or near-coincident curves across a large number of publications, a finding also inconsistent with random sampling. Combining the continuous and categorical probabilities of the 32 included trials, we found a very low likelihood of random sampling: p = 1.27 × 10(-8) (1 in 100,000,000). The high probability of non-random sampling and the repetition of lines in multiple graphs suggest that further scrutiny of Saitoh's work is warranted. © 2016 The Association of Anaesthetists of Great Britain and Ireland.

  9. Professional kinesiology practice for chronic low back pain: single-blind, randomised controlled pilot study.

    PubMed

    Eardley, S; Brien, S; Little, P; Prescott, P; Lewith, G

    2013-01-01

    Chronic low back pain is a highly prevalent condition with no definitive treatment. Professional Kinesiology Practice (PKP) is a little known complementary medicine technique using non-standard muscle testing; no previous effectiveness studies have been performed. This is an exploratory, pragmatic single-blind, 3-arm randomised sham-controlled pilot study with waiting list control (WLC) in private practice UK (2007-2009). 70 participants scoring ≥4 on the Roland and Morris Disability Questionnaire (RMDQ) were randomised to real or sham PKP receiving 1 treatment weekly for 5 weeks or a WLC. WLC's were re-randomised to real or sham after 6 weeks. The main outcome was a change in RMDQ from baseline to end of 5 weeks of real or sham PKP. With an effect size of 0.7 real treatment was significantly different to sham (mean difference RMDQ score = -2.9, p = 0.04, 95% CI -5.8 to -0.1). Compared to WLC, real and sham groups had significant RMDQ improvements (real -9.0, p < 0.01, 95% CI -12.1 to -5.8; effect size 2.1; sham -6.1, p < 0.01, 95% CI -9.1 to -3.1; effect size 1.4). Practitioner empathy (CARE) and patient enablement (PEI) did not predict outcome; holistic health beliefs (CAMBI) did, though. The sham treatment appeared credible; patients did not guess treatment allocation. 3 patients reported minor adverse reactions. Real treatment was significantly different from sham demonstrating a moderate specific effect of PKP; both were better than WLC indicating a substantial non-specific and contextual treatment effect. A larger definitive study would be appropriate with nested qualitative work to help understand the mechanisms involved in PKP.

  10. Results of a feasibility randomised controlled study of the guidelines for exercise in multiple sclerosis project.

    PubMed

    Learmonth, Yvonne C; Adamson, Brynn C; Kinnett-Hopkins, Dominique; Bohri, Maria; Motl, Robert W

    2017-03-01

    There is increasing recognition that exercise is an efficacious strategy for managing many consequences of multiple sclerosis (MS), yet persons with MS are not engaging in sufficient exercise for accruing health benefits. Poor exercise uptake might be associated with the design of previous research. We conducted a randomised controlled trial (RCT) for examining the feasibility of a 4-month home-based, exercise-training program designed based on recent physical activity guidelines for MS and supplemented by behavioural strategies for compliance. Feasibility was assessed in the domains of process (e.g., recruitment), resource (e.g., monetary costs), management (e.g., personnel time requirements) and scientific outcomes (e.g., treatment effect). We recruited persons with mild-to-moderate MS who were randomised into an intervention or wait-list control condition. Intervention participants received a pedometer, elastic resistance bands, DVD, training manual, calendars, log-book, video coaching calls and newsletters. Participants in both conditions completed home-based assessments before and after the 4-month period. Ninety-nine persons with MS were assessed for eligibility, and 57 were randomised. Fifty-one persons completed the study (90%). Total costs of the study were US $5331.03. Personnel time to conduct the study totaled 263h. Participants in the intervention group complied fully with 71% of all exercise sessions. There was a moderate increase in self-reported exercise behaviour of the intervention participants as measured by the Godin Leisure-Time Exercise Questionnaire (d≥0.5). The results support the feasibility and acceptability of a home-based exercise intervention based on physical activity guidelines and supplemented with behavioural strategies for adults with mild-to-moderate MS.

  11. TOPPITS: Trial Of Proton Pump Inhibitors in Throat Symptoms. Study protocol for a randomised controlled trial.

    PubMed

    Watson, Gillian; O'Hara, James; Carding, Paul; Lecouturier, Jan; Stocken, Deborah; Fouweather, Tony; Wilson, Janet

    2016-04-01

    Persistent throat symptoms and Extra Oesophageal Reflux (EOR) are among the commonest reasons for attendance at a secondary care throat or voice clinic. There is a growing trend to treat throat symptom patients with proton pump inhibitors (PPIs) to suppress stomach acid, but most controlled studies fail to demonstrate a significant benefit of PPI over placebo. In addition, patient views on PPI use vary widely. A UK multi-centre, randomised, controlled trial for adults with persistent throat symptoms to compare the effectiveness of treatment with the proton pump inhibitor (PPI) lansoprazole versus placebo. The trial includes a six-month internal pilot, during which three sites will recruit 30 participants in total, to assess the practicality of the trial and assess the study procedures and willingness of the patient population to participate. If the pilot is successful, three additional sites will be opened to recruitment, and a further 302 participants recruited across the six main trial sites. Further trial sites may be opened, as necessary. The main trial will continue for a further 18 months. Participants will be followed up for 12 months from randomisation, throughout which both primary and secondary outcome data will be collected. The primary outcome is change in Reflux Symptom Index (RSI) score, the 'area standard' for this type of assessment, after 16 weeks (four months) of treatment. Secondary outcomes are RSI changes at 12 months after randomisation, Quality of Life assessment at four and 12 months, laryngeal mucosal changes, assessments of compliance and side effects, and patient-reported satisfaction. TOPPITS is designed to evaluate the relative effectiveness of treatment with a proton pump inhibitor versus placebo in patients with persistent throat symptoms. This will provide valuable information to clinicians and GPs regarding the treatment and management of care for these patients, on changes in symptoms, and in Quality of Life, over time. ISRCTN

  12. Reporting of radiographic methods in randomised controlled trials assessing structural outcomes in rheumatoid arthritis

    PubMed Central

    Baron, Gabriel; Boutron, Isabelle; Giraudeau, Bruno; Ravaud, Philippe

    2007-01-01

    Background Because an increasing number of clinical trials evaluating disease‐modifying antirheumatic drugs in rheumatoid arthritis (RA) emphasise radiographic outcomes as a primary outcome, using a reproducible radiographic measure should be placed at a premium. Aim To evaluate the reporting of radiographic methods in randomised trials assessing radiographic outcomes in RA. Methods Medline was searched for randomised controlled trials assessing radiographic outcomes published between January 1994 and December 2005 in general medical and specialty journals with a high impact factor. One reader extracted data (radiographic acquisition, assessment and reproducibility) using a standardised form. Results A total of 46 reports were included in the analysis. The mean (SD) methodological quality scores on the Jadad scale (range 0–5) and the Delphi list (0–9) were 2.9 (1.2) and 6.4 (1.3), respectively. Use of a standardised procedure for the acquisition of the radiographs was reported in 2 (4.3%) articles. 2 (4.3%) reports indicated that the quality of the radiographs was evaluated. In 65.2% of the reports, ⩾2 radiographic scores were used. Reporting of radiographic assessment was well detailed for number of readers (91.3%), information on readers (71.7%), blinding (91.4%) and how films were viewed (74.0%). The reproducibility of the reading was reported in 39.1% of the articles. Conclusion The reporting of results of randomised controlled trials of radiographic outcomes in RA shows great variability in radiographic scores used. Reporting of radiographic methods could be improved upon, especially the acquisition procedure and the reproducibility of the reading. PMID:17158823

  13. Robust H ∞ control of a nonlinear uncertain system via a stable nonlinear output feedback controller

    NASA Astrophysics Data System (ADS)

    Harno, Hendra G.; Petersen, Ian R.

    2011-04-01

    A new approach to solving a nonlinear robust H ∞ control problem using a stable nonlinear output feedback controller is presented in this article. The class of nonlinear uncertain systems being considered is characterised in terms of integral quadratic constraints and global Lipschitz conditions describing the admissible uncertainties and nonlinearities, respectively. The nonlinear controller is able to exploit the plant nonlinearities through the inclusion of a copy of the known plant nonlinearities in the controller. The H ∞ control objective is to obtain an absolutely stable closed-loop system with a specified disturbance attenuation level. The solution to this control problem involves stabilising solutions to parametrised algebraic Riccati equations. We apply a differential evolution algorithm to solve a non-convex nonlinear optimisation problem arising in the controller synthesis.

  14. Effects of vitamin E on stroke subtypes: meta-analysis of randomised controlled trials.

    PubMed

    Schürks, Markus; Glynn, Robert J; Rist, Pamela M; Tzourio, Christophe; Kurth, Tobias

    2010-11-04

    To evaluate the effect of vitamin E supplementation on incident total, ischaemic, and haemorrhagic stroke. Systematic review and meta-analysis of randomised, placebo controlled trials published until January 2010. Electronic databases (Medline, Embase, Cochrane Central Register of Controlled Trials) and reference lists of trial reports. Selection criteria Randomised, placebo controlled trials with ≥1 year of follow-up investigating the effect of vitamin E on stroke. Review methods and data extraction Two investigators independently assessed eligibility of identified trials. Disagreements were resolved by consensus. Two different investigators independently extracted data. Risk ratios (and 95% confidence intervals) were calculated for each trial based on the number of cases and non-cases randomised to vitamin E or placebo. Pooled effect estimates were then calculated. Nine trials investigating the effect of vitamin E on incident stroke were included, totalling 118 765 participants (59 357 randomised to vitamin E and 59 408 to placebo). Among those, seven trials reported data for total stroke and five trials each for haemorrhagic and ischaemic stroke. Vitamin E had no effect on the risk for total stroke (pooled relative risk 0.98 (95% confidence interval 0.91 to 1.05), P=0.53). In contrast, the risk for haemorrhagic stroke was increased (pooled relative risk 1.22 (1.00 to 1.48),