Science.gov

Sample records for adaptive control strategies

  1. Adaptive Control Strategies for Flexible Robotic Arm

    NASA Technical Reports Server (NTRS)

    Bialasiewicz, Jan T.

    1996-01-01

    The control problem of a flexible robotic arm has been investigated. The control strategies that have been developed have a wide application in approaching the general control problem of flexible space structures. The following control strategies have been developed and evaluated: neural self-tuning control algorithm, neural-network-based fuzzy logic control algorithm, and adaptive pole assignment algorithm. All of the above algorithms have been tested through computer simulation. In addition, the hardware implementation of a computer control system that controls the tip position of a flexible arm clamped on a rigid hub mounted directly on the vertical shaft of a dc motor, has been developed. An adaptive pole assignment algorithm has been applied to suppress vibrations of the described physical model of flexible robotic arm and has been successfully tested using this testbed.

  2. An adaptive strategy for controlling chaotic system.

    PubMed

    Cao, Yi-Jia; Hang, Hong-Xian

    2003-01-01

    This paper presents an adaptive strategy for controlling chaotic systems. By employing the phase space reconstruction technique in nonlinear dynamical systems theory, the proposed strategy transforms the nonlinear system into canonical form, and employs a nonlinear observer to estimate the uncertainties and disturbances of the nonlinear system, and then establishes a state-error-like feedback law. The developed control scheme allows chaos control in spite of modeling errors and parametric variations. The effectiveness of the proposed approach has been demonstrated through its applications to two well-known chaotic systems: Duffing oscillator and Rössler chaos.

  3. Adaptive control strategies for flexible robotic arm

    NASA Technical Reports Server (NTRS)

    Bialasiewicz, Jan T.

    1993-01-01

    The motivation of this research came about when a neural network direct adaptive control scheme was applied to control the tip position of a flexible robotic arm. Satisfactory control performance was not attainable due to the inherent non-minimum phase characteristics of the flexible robotic arm tip. Most of the existing neural network control algorithms are based on the direct method and exhibit very high sensitivity if not unstable closed-loop behavior. Therefore a neural self-tuning control (NSTC) algorithm is developed and applied to this problem and showed promising results. Simulation results of the NSTC scheme and the conventional self-tuning (STR) control scheme are used to examine performance factors such as control tracking mean square error, estimation mean square error, transient response, and steady state response.

  4. A flicker reduction control strategy using an adaptive var compensator

    SciTech Connect

    Jatskevich, J.; Wasynczuk, O.; Conrad, L.

    1999-11-01

    A detailed computer model of a power network with loads, resistance welders and an Adaptive Var Compensator (AVC) has been developed and used to determine the effectiveness of the AVC on the reduction of observable flicker at neighboring loads. Flicker severity is determined using the UIE/IEC flickermeter methodology. Different control strategies for the AVC are considered and compared with respect to flicker reduction. A new flicker adaptive control (FAC) strategy is proposed that can be used for both power factor correction and flicker reduction. The measurement technique used in the FAC is shown to be accurate even in presence of significant harmonic distortion.

  5. Adaptive Insecure Attachment and Resource Control Strategies during Middle Childhood

    ERIC Educational Resources Information Center

    Chen, Bin-Bin; Chang, Lei

    2012-01-01

    By integrating the life history theory of attachment with resource control theory, the current study examines the hypothesis that insecure attachment styles reorganized in middle childhood are alternative adaptive strategies used to prepare for upcoming competition with the peer group. A sample of 654 children in the second through seventh grades…

  6. Adaptive Insecure Attachment and Resource Control Strategies during Middle Childhood

    ERIC Educational Resources Information Center

    Chen, Bin-Bin; Chang, Lei

    2012-01-01

    By integrating the life history theory of attachment with resource control theory, the current study examines the hypothesis that insecure attachment styles reorganized in middle childhood are alternative adaptive strategies used to prepare for upcoming competition with the peer group. A sample of 654 children in the second through seventh grades…

  7. A control strategy for adaptive absorber based on variable mass

    NASA Astrophysics Data System (ADS)

    Gao, Qiang; Han, Ning; Zhao, Yanqing; Duan, Chendong; Wang, Wanqin

    2015-07-01

    The tuned vibration absorber (TVA) has been an effective tool for vibration control. However, the application of TVA can cause resonance of the primary system and increase its vibration when the absorber is mistuned. In this paper, a novel control strategy based on adaptive tuned vibration absorber (ATVA) of variable mass is proposed to reduce the resonance of the primary system. Unlike most ATVAs suggested by other researchers which adjust the absorber natural frequency by changing the stiffness, the variable mass ATVA varies its natural frequency by changing absorber mass to match the excitation frequency. Some simulations and experiments were conducted to test the performance of the control strategy. The results show that the proposed control plan can widen the frequency bandwidth of the absorber, as well as suppress the resonance of the primary system significantly. This implies that the work is useful for practical applications of ATVA.

  8. Controls on Extreme Droughts and Adaptation Strategies in Semiarid Regions

    NASA Astrophysics Data System (ADS)

    Scanlon, B. R.; Cook, C.; Fernando, D. N.; LeBlanc, M.

    2012-12-01

    Increasing vulnerability to droughts with reduced per capita water storage, particularly in semiarid regions, underscores the need for predictive understanding of drought controls and development of adaptation strategies for water resources management. In this study we evaluate causes of major droughts in southwest and southcentral US (California and Texas) and southeast Australia (Murray Darling Basin). Impacts of climate cycles (ENSO, PDO, AMO, NAO, IOD) and atmospheric circulation on drought initiation and persistence are examined. Effects of drought on surface water reservoir storage, groundwater storage, irrigation, and crop production are compared. Adaptation strategies being evaluated include water transfers among sectors, particularly from irrigated agriculture to other groups, increasing storage using managed aquifer recharge, water reuse, and development of new water sources (e.g. seawater desalination). It is critical to develop a broad portfolio of water sources to increase resilience to future droughts.

  9. Self-Adaptive Differential Evolution Algorithm With Zoning Evolution of Control Parameters and Adaptive Mutation Strategies.

    PubMed

    Fan, Qinqin; Yan, Xuefeng

    2016-01-01

    The performance of the differential evolution (DE) algorithm is significantly affected by the choice of mutation strategies and control parameters. Maintaining the search capability of various control parameter combinations throughout the entire evolution process is also a key issue. A self-adaptive DE algorithm with zoning evolution of control parameters and adaptive mutation strategies is proposed in this paper. In the proposed algorithm, the mutation strategies are automatically adjusted with population evolution, and the control parameters evolve in their own zoning to self-adapt and discover near optimal values autonomously. The proposed algorithm is compared with five state-of-the-art DE algorithm variants according to a set of benchmark test functions. Furthermore, seven nonparametric statistical tests are implemented to analyze the experimental results. The results indicate that the overall performance of the proposed algorithm is better than those of the five existing improved algorithms.

  10. Management of Computer-Based Instruction: Design of an Adaptive Control Strategy.

    ERIC Educational Resources Information Center

    Tennyson, Robert D.; Rothen, Wolfgang

    1979-01-01

    Theoretical and research literature on learner, program, and adaptive control as forms of instructional management are critiqued in reference to the design of computer-based instruction. An adaptive control strategy using an online, iterative algorithmic model is proposed. (RAO)

  11. A hybrid adaptive control strategy for a smart prosthetic hand.

    PubMed

    Chen, Cheng-Hung; Naidu, D Subbaram; Perez-Gracia, Alba; Schoen, Marco P

    2009-01-01

    This paper presents a hybrid of a soft computing technique of adaptive neuro-fuzzy inference system (ANFIS) and a hard computing technique of adaptive control for a two-dimensional movement of a prosthetic hand with a thumb and index finger. In particular, ANFIS is used for inverse kinematics, and the adaptive control is used for linearized dynamics to minimize tracking error. The simulations of this hybrid controller, when compared with the proportional-integral-derivative (PID) controller showed enhanced performance. Work is in progress to extend this methodology to a five-fingered, three-dimensional prosthetic hand.

  12. Dual-thread parallel control strategy for ophthalmic adaptive optics.

    PubMed

    Yu, Yongxin; Zhang, Yuhua

    To improve ophthalmic adaptive optics speed and compensate for ocular wavefront aberration of high temporal frequency, the adaptive optics wavefront correction has been implemented with a control scheme including 2 parallel threads; one is dedicated to wavefront detection and the other conducts wavefront reconstruction and compensation. With a custom Shack-Hartmann wavefront sensor that measures the ocular wave aberration with 193 subapertures across the pupil, adaptive optics has achieved a closed loop updating frequency up to 110 Hz, and demonstrated robust compensation for ocular wave aberration up to 50 Hz in an adaptive optics scanning laser ophthalmoscope.

  13. Strategy for adaptive process control for a column flotation unit

    SciTech Connect

    Karr, C.L.; Ferguson, C.R.

    1994-12-31

    Researchers at the U.S. Bureau of Mines (USBM) have developed adaptive process control systems in which genetic algorithms (GAs) are used to augment fuzzy logic controllers (FLCs). Together, GAs and FLCs possess the capabilities necessary to produce powerful, efficient, and robust adaptive control systems. To perform efficiently, such control systems require a control element to manipulate the problem environment, an analysis element to recognize changes in the problem environment, and a learning element to adjust to the changes in the problem environment. In this paper, the details of an ongoing research effort to develop and implement an adaptive process control system for a column flotation unit are discussed. Column flotation units are used extensively in the mineral processing industry to recover valuable minerals from their ores.

  14. Control Reallocation Strategies for Damage Adaptation in Transport Class Aircraft

    NASA Technical Reports Server (NTRS)

    Gundy-Burlet, Karen; Krishnakumar, K.; Limes, Greg; Bryant, Don

    2003-01-01

    This paper examines the feasibility, potential benefits and implementation issues associated with retrofitting a neural-adaptive flight control system (NFCS) to existing transport aircraft, including both cable/hydraulic and fly-by-wire configurations. NFCS uses a neural network based direct adaptive control approach for applying alternate sources of control authority in the presence of damage or failures in order to achieve desired flight control performance. Neural networks are used to provide consistent handling qualities across flight conditions, adapt to changes in aircraft dynamics and to make the controller easy to apply when implemented on different aircraft. Full-motion piloted simulation studies were performed on two different transport models: the Boeing 747-400 and the Boeing C-17. Subjects included NASA, Air Force and commercial airline pilots. Results demonstrate the potential for improving handing qualities and significantly increased survivability rates under various simulated failure conditions.

  15. Adaptive Optics Control Strategies for Extremely Large Telescopes

    SciTech Connect

    Gavel, D T

    2001-07-26

    Adaptive optics for the 30-100 meter class telescopes now being considered will require an extension in almost every area of AO system component technology. In this paper, we present scaling laws and strawman error budgets for AO systems on extremely large telescopes (ELTs) and discuss the implications for component technology and computational architecture. In the component technology area, we discuss the advanced efforts being pursued at the NSF Center for Adaptive Optics (CfAO) in the development of large number of degrees of freedom deformable mirrors, wavefront sensors, and guidestar lasers. It is important to note that the scaling of present wavefront reconstructor algorithms will become computationally intractable for ELTs and will require the development of new algorithms and advanced numerical mathematics techniques. We present the computational issues and discuss the characteristics of new algorithmic approaches that show promise in scaling to ELT AO systems.

  16. Adaptive backstepping sliding mode control with fuzzy monitoring strategy for a kind of mechanical system.

    PubMed

    Song, Zhankui; Sun, Kaibiao

    2014-01-01

    A novel adaptive backstepping sliding mode control (ABSMC) law with fuzzy monitoring strategy is proposed for the tracking-control of a kind of nonlinear mechanical system. The proposed ABSMC scheme combining the sliding mode control and backstepping technique ensure that the occurrence of the sliding motion in finite-time and the trajectory of tracking-error converge to equilibrium point. To obtain a better perturbation rejection property, an adaptive control law is employed to compensate the lumped perturbation. Furthermore, we introduce fuzzy monitoring strategy to improve adaptive capacity and soften the control signal. The convergence and stability of the proposed control scheme are proved by using Lyaponov's method. Finally, numerical simulations demonstrate the effectiveness of the proposed control scheme.

  17. Adaptive Control Strategies for Interlimb Coordination in Legged Robots: A Review.

    PubMed

    Aoi, Shinya; Manoonpong, Poramate; Ambe, Yuichi; Matsuno, Fumitoshi; Wörgötter, Florentin

    2017-01-01

    Walking animals produce adaptive interlimb coordination during locomotion in accordance with their situation. Interlimb coordination is generated through the dynamic interactions of the neural system, the musculoskeletal system, and the environment, although the underlying mechanisms remain unclear. Recently, investigations of the adaptation mechanisms of living beings have attracted attention, and bio-inspired control systems based on neurophysiological findings regarding sensorimotor interactions are being developed for legged robots. In this review, we introduce adaptive interlimb coordination for legged robots induced by various factors (locomotion speed, environmental situation, body properties, and task). In addition, we show characteristic properties of adaptive interlimb coordination, such as gait hysteresis and different time-scale adaptations. We also discuss the underlying mechanisms and control strategies to achieve adaptive interlimb coordination and the design principle for the control system of legged robots.

  18. Adaptive Control Strategies for Interlimb Coordination in Legged Robots: A Review

    PubMed Central

    Aoi, Shinya; Manoonpong, Poramate; Ambe, Yuichi; Matsuno, Fumitoshi; Wörgötter, Florentin

    2017-01-01

    Walking animals produce adaptive interlimb coordination during locomotion in accordance with their situation. Interlimb coordination is generated through the dynamic interactions of the neural system, the musculoskeletal system, and the environment, although the underlying mechanisms remain unclear. Recently, investigations of the adaptation mechanisms of living beings have attracted attention, and bio-inspired control systems based on neurophysiological findings regarding sensorimotor interactions are being developed for legged robots. In this review, we introduce adaptive interlimb coordination for legged robots induced by various factors (locomotion speed, environmental situation, body properties, and task). In addition, we show characteristic properties of adaptive interlimb coordination, such as gait hysteresis and different time-scale adaptations. We also discuss the underlying mechanisms and control strategies to achieve adaptive interlimb coordination and the design principle for the control system of legged robots. PMID:28878645

  19. Loss of control eating in adolescents: Associations with adaptive and maladaptive emotion regulation strategies.

    PubMed

    Goossens, Lien; Van Malderen, Eva; Van Durme, Kim; Braet, Caroline

    2016-08-01

    To examine differences in the use of emotion regulation strategies in adolescents with and without loss of control over eating (LOC). A community-based sample of 524 adolescents from 12 to 18years old (70.6% girls; Mage=15.08; SD=1.59) reported on LOC and the use of several maladaptive and adaptive emotion regulation strategies. Adolescents who experience LOC (28%) report more use of maladaptive strategies. With regard to adaptive strategies a significant group X gender interaction effect was found with girls who report LOC using less adaptive strategies. More specifically, based on the FEEL-KJ less problem-oriented action, distraction, humor enhancement, acceptance and cognitive problem solving were observed in girls who report LOC compared to those who do not report LOC. Boys with LOC report more use of adaptive strategies compared to those who do not report LOC. LOC in adolescents is associated with increased use of maladaptive emotion regulation strategies as well as a decreased use of adaptive strategies although the latter is only specific for girls. These results may inform prevention and treatment of emotion regulation problems in adolescents with LOC. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Fuel consumptions and exhaust emissions induced by cooperative adaptive cruise control strategies

    NASA Astrophysics Data System (ADS)

    Yu, Shaowei; Shi, Zhongke

    2015-04-01

    Many cooperative adaptive cruise control strategies have been presented to improve traffic efficiency as well as road traffic safety, but scholars have rarely explored the impacts of these strategies on cars' fuel consumptions and exhaust emissions. In this paper, we respectively select two-velocity difference model, multiple velocity difference model and the car-following model considering multiple preceding cars' accelerations to investigate each car's fuel consumptions, carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOX) emissions and carry out comparative analysis. The comparisons of fuel consumptions and exhaust emissions in three different cruise control strategies show that cooperative cars simulated by the car-following model considering multiple preceding cars' accelerations can run with the minimal fuel consumptions, CO, HC and NOX emissions, thus, taking the car-following model considering multiple preceding cars' accelerations as the cooperative adaptive cruise control strategy can significantly improve cars' fuel efficiency and exhaust emissions.

  1. Adaptive pinning control: A review of the fully decentralized strategy and its extensions

    NASA Astrophysics Data System (ADS)

    Turci, L. F. R.; De Lellis, P.; Macau, E. E. N.; Di Bernardo, M.; Simões, M. M. R.

    2014-12-01

    In this work, we review recent developments related to the problem of guiding a complex network of agents toward a synchronized state. Specifically, we focus on adaptive pinning control strategies, expounding those developed by the authors in the context of the existing literature, in which only a small fraction of the network nodes is directly controlled. The methodologies described herein are adaptive in the sense that the control and coupling gains are updated on the basis of the local mismatch with the desired trajectory and between coupled nodes, respectively. A selection of adaptive strategies recently proposed in the literature is reviewed, and the main stability results are expounded. As a numerical validation, the selected approaches are applied to control an ensemble of coupled mobile agents moving in a formation.

  2. Learner Control versus Program Control as Adaptive Strategies for Selection of Instructional Support on Math Rules.

    ERIC Educational Resources Information Center

    Ross, Steven M.; Rakow, Ernest A.

    1981-01-01

    Subjects completed a self-paced lesson on math rules in which the number of supporting examples was adapted to pretest scores through program control, selected through learner control, or kept constant (nonadaptive). Program control means were consistently highest while learner control means were lowest. (Author/BW)

  3. Adaptive terminal sliding-mode control strategy for DC-DC buck converters.

    PubMed

    Komurcugil, Hasan

    2012-11-01

    This paper presents an adaptive terminal sliding mode control (ATSMC) strategy for DC-DC buck converters. The idea behind this strategy is to use the terminal sliding mode control (TSMC) approach to assure finite time convergence of the output voltage error to the equilibrium point and integrate an adaptive law to the TSMC strategy so as to achieve a dynamic sliding line during the load variations. In addition, the influence of the controller parameters on the performance of closed-loop system is investigated. It is observed that the start up response of the output voltage becomes faster with increasing value of the fractional power used in the sliding function. On the other hand, the transient response of the output voltage, caused by the step change in the load, becomes faster with decreasing the value of the fractional power. Therefore, the value of fractional power is to be chosen to make a compromise between start up and transient responses of the converter. Performance of the proposed ATSMC strategy has been tested through computer simulations and experiments. The simulation results of the proposed ATSMC strategy are compared with the conventional SMC and TSMC strategies. It is shown that the ATSMC exhibits a considerable improvement in terms of a faster output voltage response during load changes.

  4. Cortisol secretion and functional disabilities in old age: importance of using adaptive control strategies.

    PubMed

    Wrosch, Carsten; Miller, Gregory E; Schulz, Richard

    2009-11-01

    To examine whether the use of health-related control strategies moderates the association between elevated diurnal cortisol secretion and increases in older adults' functional disabilities. Functional disabilities of 164 older adults were assessed over 4 years by measuring participants' problems with performing activities of daily living. The main predictors included baseline levels of diurnal cortisol secretion and control strategies used to manage physical health threats. A large increase in functional disabilities was observed among participants who secreted elevated baseline levels of cortisol and did not use health-related control strategies. By contrast, high cortisol level was not associated with increases in functional disabilities among participants who reported using these control strategies. Among participants with low cortisol level, there was a relatively smaller increase in functional disabilities over time, and the use of control strategies was not significantly associated with changes in functional disabilities. The findings suggest that high cortisol level is associated with an increase in older adults' functional disabilities, but only if older adults do not engage in adaptive control strategies.

  5. Adaptive Optics Facility: control strategy and first on-sky results of the acquisition sequence

    NASA Astrophysics Data System (ADS)

    Madec, P.-Y.; Kolb, J.; Oberti, S.; Paufique, J.; La Penna, P.; Hackenberg, W.; Kuntschner, H.; Argomedo, J.; Kiekebusch, M.; Donaldson, R.; Suarez, M.; Arsenault, R.

    2016-07-01

    The Adaptive Optics Facility is an ESO project aiming at converting Yepun, one of the four 8m telescopes in Paranal, into an adaptive telescope. This is done by replacing the current conventional secondary mirror of Yepun by a Deformable Secondary Mirror (DSM) and attaching four Laser Guide Star (LGS) Units to its centerpiece. In the meantime, two Adaptive Optics (AO) modules have been developed incorporating each four LGS WaveFront Sensors (WFS) and one tip-tilt sensor used to control the DSM at 1 kHz frame rate. The four LGS Units and one AO module (GRAAL) have already been assembled on Yepun. Besides the technological challenge itself, one critical area of AOF is the AO control strategy and its link with the telescope control, including Active Optics used to shape M1. Another challenge is the request to minimize the overhead due to AOF during the acquisition phase of the observation. This paper presents the control strategy of the AOF. The current control of the telescope is first recalled, and then the way the AO control makes the link with the Active Optics is detailed. Lab results are used to illustrate the expected performance. Finally, the overall AOF acquisition sequence is presented as well as first results obtained on sky with GRAAL.

  6. Adaptive Control for Buck Power Converter Using Fixed Point Inducting Control and Zero Average Dynamics Strategies

    NASA Astrophysics Data System (ADS)

    Hoyos Velasco, Fredy Edimer; García, Nicolás Toro; Garcés Gómez, Yeison Alberto

    In this paper, the output voltage of a buck power converter is controlled by means of a quasi-sliding scheme. The Fixed Point Inducting Control (FPIC) technique is used for the control design, based on the Zero Average Dynamics (ZAD) strategy, including load estimation by means of the Least Mean Squares (LMS) method. The control scheme is tested in a Rapid Control Prototyping (RCP) system based on Digital Signal Processing (DSP) for dSPACE platform. The closed loop system shows adequate performance. The experimental and simulation results match. The main contribution of this paper is to introduce the load estimator by means of LMS, to make ZAD and FPIC control feasible in load variation conditions. In addition, comparison results for controlled buck converter with SMC, PID and ZAD-FPIC control techniques are shown.

  7. Covariance Matrix Adapted Evolution Strategy Based Design of Mixed H2/H ∞ PID Controller

    NASA Astrophysics Data System (ADS)

    Willjuice Iruthayarajan, M.; Baskar, S.

    This paper discusses the application of the covariance matrix adapted evolution strategy (CMAES) technique to the design of the mixed H2/H ∞ PID controller. The optimal robust PID controller is designed by minimizing the weighted sum of integral squared error (ISE) and balanced robust performance criterion involving robust stability and disturbance attenuation performance subjected to robust stability and disturbance attenuation constraints. In CMAES algorithm, these constraints are effectively handled by penalty parameter-less scheme. In order to test the performance of CMAES algorithm, MIMO distillation column model is considered. For the purpose of comparison, reported intelligent genetic algorithm (IGA) method is used. The statistical performances of combined ISE and balanced robust performance criterion in ten independent simulation runs show that a performance of CMAES is better than IGA method. Robustness test conducted on the system also shows that the robust performance of CMAES designed controller is better than IGA based controller under model uncertainty and external disturbances.

  8. Comparison of Strategies for Climate Change Adaptation of Water Supply and Flood Control Reservoirs

    NASA Astrophysics Data System (ADS)

    Ng, T. L.; Yang, P.; Bhushan, R.

    2016-12-01

    With climate change, streamflows are expected to become more fluctuating, with more frequent and intense floods and droughts. This complicates reservoir operation, which is highly sensitive to inflow variability. We make a comparative evaluation of three strategies for adapting reservoirs to climate-induced shifts in streamflow patterns. Specifically, we examine the effectiveness of (i) expanding the capacities of reservoirs by way of new off-stream reservoirs, (ii) introducing wastewater reclamation to augment supplies, and (iii) improving real-time streamflow forecasts for more optimal decision-making. The first two are hard strategies involving major infrastructure modifications, while the third a soft strategy entailing adjusting the system operation. A comprehensive side-by-side comparison of the three strategies is as yet lacking in the literature despite the many past studies investigating the strategies individually. To this end, we developed an adaptive forward-looking linear program that solves to yield the optimal decisions for the current time as a function of an ensemble forecast of future streamflows. Solving the model repeatedly on a rolling basis with regular updating of the streamflow forecast simulates the system behavior over the entire operating horizon. Results are generated for two hypothetical water supply and flood control reservoirs of differing inflows and demands. Preliminary findings suggest that of the three strategies, improving streamflow forecasts to be most effective in mitigating the effects of climate change. We also found that, in average terms, both additional reservoir capacity and wastewater reclamation have potential to reduce water shortage and downstream flooding. However, in the worst case, the potential of the former to reduce water shortage is limited, and similarly so the potential of the latter to reduce downstream flooding.

  9. The effects of vehicular gap changes with memory on traffic flow in cooperative adaptive cruise control strategy

    NASA Astrophysics Data System (ADS)

    Yu, Shaowei; Shi, Zhongke

    2015-06-01

    To evaluate the impacts of new influence factor in cooperative adaptive cruise control strategy on the dynamic characteristics of traffic flow, an improved cooperative car-following model considering multiple vehicular gap changes with memory is developed to study the influences of multiple vehicular gap changes with memory on each car's speed, acceleration and relative distance. Some numerical simulations are carried out and the results show that considering multiple vehicular gap changes with memory in designing the cooperative adaptive cruise control strategy can improve the stability of traffic flow and reduce the accidental probability.

  10. An Interactive Computer-Aided Instructional Strategy and Assessment Methods for System Identification and Adaptive Control Laboratory

    ERIC Educational Resources Information Center

    Özbek, Necdet Sinan; Eker, Ilyas

    2015-01-01

    This study describes a set of real-time interactive experiments that address system identification and model reference adaptive control (MRAC) techniques. In constructing laboratory experiments that contribute to efficient teaching, experimental design and instructional strategy are crucial, but a process for doing this has yet to be defined. This…

  11. Adaptive Strategies for Controls of Flexible Arms. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Yuan, Bau-San

    1989-01-01

    An adaptive controller for a modern manipulator has been designed based on asymptotical stability via the Lyapunov criterion with the output error between the system and a reference model used as the actuating control signal. Computer simulations were carried out to test the design. The combination of the adaptive controller and a system vibration and mode shape estimator show that the flexible arm should move along a pre-defined trajectory with high-speed motion and fast vibration setting time. An existing computer-controlled prototype two link manipulator, RALF (Robotic Arm, Large Flexible), with a parallel mechanism driven by hydraulic actuators was used to verify the mathematical analysis. The experimental results illustrate that assumed modes found from finite element techniques can be used to derive the equations of motion with acceptable accuracy. The robust adaptive (modal) control is implemented to compensate for unmodelled modes and nonlinearities and is compared with the joint feedback control in additional experiments. Preliminary results show promise for the experimental control algorithm.

  12. Expressing Adaptation Strategies Using Adaptation Patterns

    ERIC Educational Resources Information Center

    Zemirline, N.; Bourda, Y.; Reynaud, C.

    2012-01-01

    Today, there is a real challenge to enable personalized access to information. Several systems have been proposed to address this challenge including Adaptive Hypermedia Systems (AHSs). However, the specification of adaptation strategies remains a difficult task for creators of such systems. In this paper, we consider the problem of the definition…

  13. Expressing Adaptation Strategies Using Adaptation Patterns

    ERIC Educational Resources Information Center

    Zemirline, N.; Bourda, Y.; Reynaud, C.

    2012-01-01

    Today, there is a real challenge to enable personalized access to information. Several systems have been proposed to address this challenge including Adaptive Hypermedia Systems (AHSs). However, the specification of adaptation strategies remains a difficult task for creators of such systems. In this paper, we consider the problem of the definition…

  14. Biological control of crystal texture: a widespread strategy for adapting crystal properties to function.

    PubMed

    Berman, A; Hanson, J; Leiserowitz, L; Koetzle, T F; Weiner, S; Addadi, L

    1993-02-05

    Textures of calcite crystals from a variety of mineralized tissues belonging to organisms from four phyla were examined with high-resolution synchrotron x-ray radiation. Significant differences in coherence length and angular spread were observed between taxonomic groups. Crystals from polycrystalline skeletal ensembles were more perfect than those that function as single-crystal elements. Different anisotropic effects on crystal texture were observed for sea urchin and mollusk calcite crystals, whereas none was found for the foraminifer, Patellina, and the control calcite crystals. These results show that the manipulation of crystal texture in different organisms is under biological control and that crystal textures in some tissues are adapted to function. A better understanding of this apparently widespread biological phenomenon may provide new insights for improving synthetic crystal-containing materials.

  15. Biological control of crystal texture: A widespread strategy for adapting crystal properties to function

    SciTech Connect

    Berman, A.; Leiserowitz, L.; Weiner, S.; Addadi, L. ); Hanson, J.; Koetzle, T.F. )

    1993-02-05

    Textures of calcite crystals from a variety of mineralized tissues belong to organisms from four phyla were examined with high-resolution synchrotron x-ray radiation. Significant differences in coherence length and angular spread were observed between taxonomic groups. Crystals from polycrystalline skeletal ensembles were more perfect than those that function as single-crystal elements. Different anistropic effects on crystal texture were observed for sea urchin and mollusk calcite crystals, whereas none was found for the foraminifer, Patellina, and the control calcite crystals. These results show that the manipulation of crystal texture in different organisms is under biological control and that crystal textures in some tissues are adapted to function. A better understanding of this apparently widespread biological phenomenon may provide new insights for improving synthetic crystal-containing materials. 18 refs., 3 figs., 1 tab.

  16. Building An Adaptive Cyber Strategy

    DTIC Science & Technology

    2016-06-01

    AU/ACSC/SMITH, FI/AY16 AIR COMMAND AND STAFF COLLEGE AIR UNIVERSITY BUILDING AN ADAPTIVE CYBER STRATEGY by...AY16 Abstract Due to the complexity of cyberspace and the diversity of threats that operate in the new domain, current US cyber strategy has not...proven effective. This paper dissects the cyber threat landscape and how advanced threats operate in order to devise an effective, adaptive strategy

  17. Worry as an adaptive avoidance strategy in healthy controls but not in pathological worriers.

    PubMed

    Ottaviani, Cristina; Borlimi, Rosita; Brighetti, Gianni; Caselli, Gabriele; Favaretto, Ettore; Giardini, Irene; Marzocchi, Camilla; Nucifora, Valeria; Rebecchi, Daniela; Ruggiero, Giovanni M; Sassaroli, Sandra

    2014-09-01

    The cognitive avoidance model of worry assumes that worry has the adaptive function to keep under control the physiological arousal associated with anxiety. This study aimed to test this model by the use of a fear induction paradigm in both pathological and healthy individuals. Thirty-one pathological worriers and 36 healthy controls accepted to be exposed to a fear induction paradigm (white noise) during three experimental conditions: worry, distraction, and reappraisal. Skin conductance (SCR) and heart rate variability (HRV) were measured as indices of sympathetic and parasympathetic nervous system functioning. Worriers showed increased sympathetic and decreased parasympathetic activation during the worry condition compared to non-worriers. There were no differences between groups for the distraction and reappraisal conditions. SCRs to the white noises during worry were higher in worriers versus controls throughout the entire worry period. Intolerance of uncertainty - but not metacognitive beliefs about worry - was a significant moderator of the relationship between worry and LF/HF-HRV in pathological worriers. Results support the cognitive avoidance model in healthy controls, suggesting that worry is no longer a functional attitude when it becomes the default/automatic and pathological response. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Strategies of Adaptive Ability Measurement.

    ERIC Educational Resources Information Center

    Weiss, David J.

    A number of strategies are described for adapting ability test items to individual differences in ability levels of testees. Each strategy consists of a different set of rules for selecting the sequence of test items to be administered to a given testee. Advantages and disadvantages of each strategy are discussed, and research issues unique to the…

  19. Non-MTC gait cycles: An adaptive toe trajectory control strategy in older adults.

    PubMed

    Santhiranayagam, Braveena K; Sparrow, W A; Lai, Daniel T H; Begg, Rezaul K

    2017-03-01

    Minimum-toe-clearance (MTC) above the walking surface is a critical representation of toe-trajectory control due to its association with tripping risk. Not all gait cycles exhibit a clearly defined MTC within the swing phase but there have been few previous accounts of the biomechanical characteristics of non-MTC gait cycles. The present report investigated the within-subject non-MTC gait cycle characteristics of 15 older adults (mean 73.1 years) and 15 young controls (mean 26.1 years). Participants performed the following tasks on a motorized treadmill: preferred speed walking, dual task walking (carrying a glass of water) and a dual-task speed-matched control. Toe position-time coordinates were acquired using a 3 dimensional motion capture system. When MTC was present, toe height at MTC (MTCheight) was extracted. The proportion of non-MTC gait cycles was computed for the age groups and individuals. For non-MTC gait cycles an 'indicative' toe height at the individual's average swing phase time (MTCtime) for observed MTC cycles was averaged across multiple non-MTC gait cycles. In preferred-speed walking Young demonstrated 2.9% non-MTC gait cycles and Older 18.7%. In constrained walking conditions both groups increased non-MTC gait cycles and some older adults revealed over 90%, confirming non-MTC gait cycles as an ageing-related phenomenon in lower limb trajectory control. For all participants median indicative toe-height on non-MTC gait cycles was greater than median MTCheight. This result suggests that eliminating the biomechanically hazardous MTC event by adopting more of the higher-clearance non-MTC gait cycles, is adaptive in reducing the likelihood of toe-ground contact. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Toward robust adaptive radiation therapy strategies.

    PubMed

    Böck, Michelle; Eriksson, Kjell; Forsgren, Anders; Hårdemark, Björn

    2017-06-01

    -at-risk protection. In case of unpredictably larger treatment errors, the first strategy in combination with at most weekly adaptation performs best at notably improving treatment quality in terms of target coverage and organ-at-risk protection in comparison with a non-adaptive approach and the other adaptive strategies. The authors present a framework that provides robust plan re-optimization or margin adaptation of a treatment plan in response to interfractional geometric errors throughout the fractionated treatment. According to the simulations, these robust adaptive treatment strategies are able to identify candidates for an adaptive treatment, thus giving the opportunity to provide individualized plans, and improve their treatment quality through adaptation. The simulated robust adaptive framework is a guide for further development of optimally controlled robust adaptive therapy models. © 2017 American Association of Physicists in Medicine.

  1. A new numerical strategy with space-time adaptivity and error control for multi-scale streamer discharge simulations

    NASA Astrophysics Data System (ADS)

    Duarte, Max; Bonaventura, Zdeněk; Massot, Marc; Bourdon, Anne; Descombes, Stéphane; Dumont, Thierry

    2012-02-01

    This paper presents a new resolution strategy for multi-scale streamer discharge simulations based on a second order time adaptive integration and space adaptive multiresolution. A classical fluid model is used to describe plasma discharges, considering drift-diffusion equations and the computation of electric field. The proposed numerical method provides a time-space accuracy control of the solution, and thus, an effective accurate resolution independent of the fastest physical time scale. An important improvement of the computational efficiency is achieved whenever the required time steps go beyond standard stability constraints associated with mesh size or source time scales for the resolution of the drift-diffusion equations, whereas the stability constraint related to the dielectric relaxation time scale is respected but with a second order precision. Numerical illustrations show that the strategy can be efficiently applied to simulate the propagation of highly nonlinear ionizing waves as streamer discharges, as well as highly multi-scale nanosecond repetitively pulsed discharges, describing consistently a broad spectrum of space and time scales as well as different physical scenarios for consecutive discharge/post-discharge phases, out of reach of standard non-adaptive methods.

  2. Performance adaptive training control strategy for recovering wrist movements in stroke patients: a preliminary, feasibility study

    PubMed Central

    2009-01-01

    Background In the last two decades robot training in neuromotor rehabilitation was mainly focused on shoulder-elbow movements. Few devices were designed and clinically tested for training coordinated movements of the wrist, which are crucial for achieving even the basic level of motor competence that is necessary for carrying out ADLs (activities of daily life). Moreover, most systems of robot therapy use point-to-point reaching movements which tend to emphasize the pathological tendency of stroke patients to break down goal-directed movements into a number of jerky sub-movements. For this reason we designed a wrist robot with a range of motion comparable to that of normal subjects and implemented a self-adapting training protocol for tracking smoothly moving targets in order to facilitate the emergence of smoothness in the motor control patterns and maximize the recovery of the normal RoM (range of motion) of the different DoFs (degrees of Freedom). Methods The IIT-wrist robot is a 3 DoFs light exoskeleton device, with direct-drive of each DoF and a human-like range of motion for Flexion/Extension (FE), Abduction/Adduction (AA) and Pronation/Supination (PS). Subjects were asked to track a variable-frequency oscillating target using only one wrist DoF at time, in such a way to carry out a progressive splinting therapy. The RoM of each DoF was angularly scanned in a staircase-like fashion, from the "easier" to the "more difficult" angular position. An Adaptive Controller evaluated online performance parameters and modulated both the assistance and the difficulty of the task in order to facilitate smoother and more precise motor command patterns. Results Three stroke subjects volunteered to participate in a preliminary test session aimed at verify the acceptability of the device and the feasibility of the designed protocol. All of them were able to perform the required task. The wrist active RoM of motion was evaluated for each patient at the beginning and at the end

  3. Self-Adaptive Strategy Based on Fuzzy Control Systems for Improving Performance in Wireless Sensors Networks.

    PubMed

    Hernández Díaz, Vicente; Martínez, José-Fernán; Lucas Martínez, Néstor; del Toro, Raúl M

    2015-09-18

    The solutions to cope with new challenges that societies have to face nowadays involve providing smarter daily systems. To achieve this, technology has to evolve and leverage physical systems automatic interactions, with less human intervention. Technological paradigms like Internet of Things (IoT) and Cyber-Physical Systems (CPS) are providing reference models, architectures, approaches and tools that are to support cross-domain solutions. Thus, CPS based solutions will be applied in different application domains like e-Health, Smart Grid, Smart Transportation and so on, to assure the expected response from a complex system that relies on the smooth interaction and cooperation of diverse networked physical systems. The Wireless Sensors Networks (WSN) are a well-known wireless technology that are part of large CPS. The WSN aims at monitoring a physical system, object, (e.g., the environmental condition of a cargo container), and relaying data to the targeted processing element. The WSN communication reliability, as well as a restrained energy consumption, are expected features in a WSN. This paper shows the results obtained in a real WSN deployment, based on SunSPOT nodes, which carries out a fuzzy based control strategy to improve energy consumption while keeping communication reliability and computational resources usage among boundaries.

  4. Self-Adaptive Strategy Based on Fuzzy Control Systems for Improving Performance in Wireless Sensors Networks

    PubMed Central

    Hernández Díaz, Vicente; Martínez, José-Fernán; Lucas Martínez, Néstor; del Toro, Raúl M.

    2015-01-01

    The solutions to cope with new challenges that societies have to face nowadays involve providing smarter daily systems. To achieve this, technology has to evolve and leverage physical systems automatic interactions, with less human intervention. Technological paradigms like Internet of Things (IoT) and Cyber-Physical Systems (CPS) are providing reference models, architectures, approaches and tools that are to support cross-domain solutions. Thus, CPS based solutions will be applied in different application domains like e-Health, Smart Grid, Smart Transportation and so on, to assure the expected response from a complex system that relies on the smooth interaction and cooperation of diverse networked physical systems. The Wireless Sensors Networks (WSN) are a well-known wireless technology that are part of large CPS. The WSN aims at monitoring a physical system, object, (e.g., the environmental condition of a cargo container), and relaying data to the targeted processing element. The WSN communication reliability, as well as a restrained energy consumption, are expected features in a WSN. This paper shows the results obtained in a real WSN deployment, based on SunSPOT nodes, which carries out a fuzzy based control strategy to improve energy consumption while keeping communication reliability and computational resources usage among boundaries. PMID:26393612

  5. Strategies of Adaptive Ability Measurement.

    DTIC Science & Technology

    A number of strategies are described for adapting ability test items to individual differences in ability levels of testees. Each strategy consists of a different set of rules for selecting the sequence of test items to be administered to a given testee. Advantages and disadvantages of each strategy are discussed, and research issues unique to the strategy are described. Strategies reviewed are differentiated into two-stage approaches and multi-stage approaches. Several variations of the two-stage approach are described. The various

  6. The Effect of Adaptive, Advisement, and Linear CAI Control Strategies on the Learning of Mathematics Rules.

    ERIC Educational Resources Information Center

    Goetzfried, Leslie; Hannafin, Michael

    This study examined the effects of the locus of three computer assisted instruction (CAI) strategies on the accuracy and efficiency of mathematics rule and application learning of 47 low-achieving seventh grade students in remedial mathematics classes. The instructional task was a mathematics rule lesson concerning divisibility by the numbers two,…

  7. Hybrid Adaptive Flight Control with Model Inversion Adaptation

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan

    2011-01-01

    This study investigates a hybrid adaptive flight control method as a design possibility for a flight control system that can enable an effective adaptation strategy to deal with off-nominal flight conditions. The hybrid adaptive control blends both direct and indirect adaptive control in a model inversion flight control architecture. The blending of both direct and indirect adaptive control provides a much more flexible and effective adaptive flight control architecture than that with either direct or indirect adaptive control alone. The indirect adaptive control is used to update the model inversion controller by an on-line parameter estimation of uncertain plant dynamics based on two methods. The first parameter estimation method is an indirect adaptive law based on the Lyapunov theory, and the second method is a recursive least-squares indirect adaptive law. The model inversion controller is therefore made to adapt to changes in the plant dynamics due to uncertainty. As a result, the modeling error is reduced that directly leads to a decrease in the tracking error. In conjunction with the indirect adaptive control that updates the model inversion controller, a direct adaptive control is implemented as an augmented command to further reduce any residual tracking error that is not entirely eliminated by the indirect adaptive control.

  8. Control of sound transmission into a large composite cylinder using passive, adaptive-passive and active control strategies

    NASA Astrophysics Data System (ADS)

    Johnson, Marty; Esteve, Simon; Fuller, Chris

    2003-10-01

    This work is directed at the goal of controlling the high noise levels experienced in launch vehicle payload fairings. The problem frequency range is typically below 300 Hz where passive structural damping and sound absorption treatments perform inadequately. In this paper the work conducted at Virginia Tech over the last 3 years on techniques for reducing the interior noise levels at launch using an eight ft. diameter composite cylinder as a test platform is summarized. First the theoretical development will be presented with an overview of the mechanisms of sound transmission. Then, passive control methods using optimally damped structural distributed vibration absorbers (DVAs) and acoustic Helmholtz resonators will be presented. Both theoretical results and experimental results using high level acoustic excitation (132 dB) will be described. A set of adaptive Helmholtz resonators were also built and tested and are capable of tracking changes in acoustic resonances automatically. Finally, the results from a fully active structural acoustic control experiment using distributed active vibration absorbers will be presented.

  9. New adaptive optics control strategy for petawatt-class laser chains

    NASA Astrophysics Data System (ADS)

    Varkentina, N.; Dovillaire, G.; Legrand, J.; Beaugrand, G.; Stefanon, I.; Treimany, P.; Levecq, X.

    2017-08-01

    A new generation of ultra-high intensity femtosecond petawatt- and above-class lasers requires new approaches to wavefront corrections. New challenges for adaptive optics consist in overcoming the constraints of potentially bigger diameters, larger amplitude aberrations, faster optics, higher risk of damaging optical components and faster and easier maintenance. Here we present a new technology of a mechanical deformable mirror, which has a large stroke, high temporal stability, low hysteresis, no printthrough effect, easy, safe and fast maintenance and an operating frequency up to 10 Hz. We propose the full correction of the final focal spot in the target chamber by a combination of a standard adaptive optics system, a simple focal plane camera and a phase retrieval correction process. We test the reliability of the correction system in terms of intensity variation and wavefront stability. We further verify correction robustness of the method on a large spectral bandwidth and finally perform a focal spot correction on a terawatt laser system in both low and high-power regimes.

  10. Comparison of novel physiological load-adaptive control strategies for ventricular assist devices.

    PubMed

    Habigt, Moriz; Ketelhut, Maike; Gesenhues, Jonas; Schrödel, Frank; Hein, Marc; Mechelinck, Mare; Schmitz-Rode, Thomas; Abel, Dirk; Rossaint, Rolf

    2016-11-17

    Terminal heart failure (HF) is the most prevalent cause of death in the Western world and the implantation of a left ventricular assist device (LVAD) has become the gold standard therapy today. Most of the actually implanted devices are driven at a constant speed (CS) regardless of the patient's physiological demand. A new physiological controller [power ratio (PR) controller], which keeps a constant ratio between LVAD power and left ventricular power, a previous concept [preload responsive speed (PRS) controller], which adds a variable LVAD power to reach a defined stroke work, and a CS controller were compared with an unimpaired ventricle in a full heart computer simulation model. The effects of changes in preload, afterload and left ventricular contractility are displayed by global hemodynamics and ventricular pressure-volume loops. Both physiological controllers demonstrated the desired load dependency, whereas the PR controller exceeded the PRS controller in response to an increased load and contractility. Response was inferior when preload or contractility was decreased. Thus, the PR controller might lead to an increased exercise tolerance of the patient. Additional studies are required to evaluate the controllers in vivo.

  11. Synthetic physiology strategies for adapting tools from nature for genetically targeted control of fast biological processes.

    PubMed

    Chow, Brian Y; Chuong, Amy S; Klapoetke, Nathan C; Boyden, Edward S

    2011-01-01

    The life and operation of cells involve many physiological processes that take place over fast timescales of milliseconds to minutes. Genetically encoded technologies for driving or suppressing specific fast physiological processes in intact cells, perhaps embedded within intact tissues in living organisms, are critical for the ability to understand how these physiological processes contribute to emergent cellular and organismal functions and behaviors. Such "synthetic physiology" tools are often incredibly complex molecular machines, in part because they must operate at high speeds, without causing side effects. We here explore how synthetic physiology molecules can be identified and deployed in cells, and how the physiology of these molecules in cellular contexts can be assessed and optimized. For concreteness, we discuss these methods in the context of the "optogenetic" light-gated ion channels and pumps that we have developed over the past few years as synthetic physiology tools and widely disseminated for use in neuroscience for probing the role of specific brain cell types in neural computations, behaviors, and pathologies. We anticipate that some of the insights revealed here may be of general value for the field of synthetic physiology, as they raise issues that will be of importance for the development and use of high-performance, high-speed, side-effect free physiological control tools in heterologous expression systems.

  12. Dual-arm manipulators with adaptive control

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun (Inventor)

    1991-01-01

    The described and improved multi-arm invention of this application presents three strategies for adaptive control of cooperative multi-arm robots which coordinate control over a common load. In the position-position control strategy, the adaptive controllers ensure that the end-effector positions of both arms track desired trajectories in Cartesian space despite unknown time-varying interaction forces exerted through a load. In the position-hybrid control strategy, the adaptive controller of one arm controls end-effector motions in the free directions and applied forces in the constraint directions; while the adaptive controller of the other arm ensures that the end-effector tracks desired position trajectories. In the hybrid-hybrid control strategy, the adaptive controllers ensure that both end-effectors track reference position trajectories while simultaneously applying desired forces on the load. In all three control strategies, the cross-coupling effects between the arms are treated as disturbances which are compensated for by the adaptive controllers while following desired commands in a common frame of reference. The adaptive controllers do not require the complex mathematical model of the arm dynamics or any knowledge of the arm dynamic parameters or the load parameters such as mass and stiffness. Circuits in the adaptive feedback and feedforward controllers are varied by novel adaptation laws.

  13. Adaptive Cruise Control

    NASA Astrophysics Data System (ADS)

    Winner, Hermann; Danner, Bernd; Steinle, Joachim

    Mit Adaptive Cruise Control, abgekürzt ACC, wird eine Fahrgeschwindigkeitsregelung bezeichnet, die sich an die Verkehrssituation anpasst. Synonyme Bezeichnungen sind Aktive Geschwindigkeitsregelung, Automatische Distanzregelung oder Abstandsregeltempomat. Im englischen Sprachraum fnden sich die weiteren Bezeichnungen Active Cruise Control, Automatic Cruise Control oder Autonomous Intelligent Cruise Control. Als markengeschützte Bezeichnungen sind Distronic und Automatische Distanz-Regelung (ADR) eingetragen.

  14. 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.

  15. Calibration of liquid crystal ultrafast pulse shaper with common-path spectral interferometry and application to coherent control with a covariance matrix adaptation evolutionary strategy

    NASA Astrophysics Data System (ADS)

    Wilson, Jesse W.; Schlup, Philip; Lunacek, Monte; Whitley, Darrell; Bartels, Randy A.

    2008-03-01

    An ultrafast pulse shaper for coherent control applications is described, complete with a simple, reliable calibration technique and an advanced learning control algorithm. The calibration technique makes use of a common-path interferometer, producing less noisy measurements than a conventional Mach-Zehnder interferometer. A covariance matrix adaptation evolutionary strategy (ES) is demonstrated to perform better than a traditional ES for high-dimensional search landscapes.

  16. Adaptive Decentralized Control

    DTIC Science & Technology

    1985-04-01

    computational requirements and response time provide strong incentives for the use of distributed control architectures. The basic focus of our research is on...ADCON (for Adaptive Decentralized CONtrol) comes from the following observations about the current status of control theory . An important aspect of...decentralized control of completely known systems still has many unresolved issues and some basic problems are yet to be answered. Under these conditions

  17. Identification and control integration strategies

    NASA Technical Reports Server (NTRS)

    Milman, Mark; Mettler, Edward; Bayard, David

    1988-01-01

    This paper describes an autonomous control concept for pointing and articulation of science instruments on the Eos (Earth observing system) NASA/NOAA platforms intended to be operational by the late 1990s. Key features of this concept include advanced control adaptation and tuning strategies which provide performance robustness over a wide range of system uncertainties and mission time criticality. System identification-control modification paradigms are synthesized to form an adaptation continuum over this extended regime of autonomous operations.

  18. Identification and control integration strategies

    NASA Technical Reports Server (NTRS)

    Milman, Mark; Mettler, Edward; Bayard, David

    1988-01-01

    This paper describes an autonomous control concept for pointing and articulation of science instruments on the Eos (Earth observing system) NASA/NOAA platforms intended to be operational by the late 1990s. Key features of this concept include advanced control adaptation and tuning strategies which provide performance robustness over a wide range of system uncertainties and mission time criticality. System identification-control modification paradigms are synthesized to form an adaptation continuum over this extended regime of autonomous operations.

  19. Adaptive hierarchical fuzzy controller

    SciTech Connect

    Raju, G.V.S.; Jun Zhou

    1993-07-01

    A methodology for designing adaptive hierarchical fuzzy controllers is presented. In order to evaluate this concept, several suitable performance indices were developed and converted to linguistic fuzzy variables. Based on those variables, a supervisory fuzzy rule set was constructed and used to change the parameters of a hierarchical fuzzy controller to accommodate the variations of system parameters. The proposed algorithm was used in feedwater flow control to a steam generator. Simulation studies are presented that illustrate the effectiveness of the approach

  20. Effect of Roy’s Adaptation Model-Guided Education on Coping Strategies of the Veterans with Lower Extremities Amputation: A Double-Blind Randomized Controlled Clinical Trial

    PubMed Central

    Farsi, Zahra; Azarmi, Somayeh

    2016-01-01

    Background: Any defect in the extremities of the body can affect different life aspects. The purpose of this study was to investigate the effect of Roy’s adaptation model-guided education on coping strategies of the veterans with lower extremities amputation. Methods: In a double-blind randomized controlled clinical trial, 60 veterans with lower extremities amputation referring to Kowsar Orthotics and Prosthetics Center of Veterans Clinic in Tehran, Iran were recruited using convenience method and randomly assigned to intervention and control groups in 2013-2014. Lazarus and Folkman coping strategies questionnaire was used to collect the data. After completing the questionnaires in both groups, maladaptive behaviours were determined in the intervention group and an education program based on Roy’s adaptation model was implemented. After 2 months, both groups completed the questionnaires again. Data were analyzed using SPSS software. Results: Independent T-test showed that the score of the dimensions of coping strategies did not have a statistically significant difference between the intervention and control groups in the pre-intervention stage (P>0.05). This test showed a statistically significant difference between the two groups in the post-intervention stage in terms of the scores of different dimensions of coping strategies (P>0.05), except in dimensions of social support seeking and positive appraisal (P>0.05). Conclusion: The findings of this research indicated that the Roy’s adaptation model-guided education improved the majority of coping strategies in veterans with lower extremities amputation. It is recommended that further interventions based on Roy’s adaptation model should be performed to improve the coping of the veterans with lower extremities amputation. Trial Registration Number: IRCT2014081118763N1 PMID:27218110

  1. Advances in Adaptive Control Methods

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan

    2009-01-01

    This poster presentation describes recent advances in adaptive control technology developed by NASA. Optimal Control Modification is a novel adaptive law that can improve performance and robustness of adaptive control systems. A new technique has been developed to provide an analytical method for computing time delay stability margin for adaptive control systems.

  2. Adaptive sequential controller

    SciTech Connect

    El-Sharkawi, M.A.; Xing, J.; Butler, N.G.; Rodriguez, A.

    1994-11-01

    An adaptive sequential controller for controlling a circuit breaker or other switching device to substantially eliminate transients on a distribution line caused by closing and opening the circuit breaker. The device adaptively compensates for changes in the response time of the circuit breaker due to aging and environmental effects. A potential transformer provides a reference signal corresponding to the zero crossing of the voltage waveform, and a phase shift comparator circuit compares the reference signal to the time at which any transient was produced when the circuit breaker closed, producing a signal indicative of the adaptive adjustment that should be made. Similarly, in controlling the opening of the circuit breaker, a current transformer provides a reference signal that is compared against the time at which any transient is detected when the circuit breaker last opened. An adaptive adjustment circuit produces a compensation time that is appropriately modified to account for changes in the circuit breaker response, including the effect of ambient conditions and aging. When next opened or closed, the circuit breaker is activated at an appropriately compensated time, so that it closes when the voltage crosses zero and opens when the current crosses zero, minimizing any transients on the distribution line. Phase angle can be used to control the opening of the circuit breaker relative to the reference signal provided by the potential transformer. 15 figs.

  3. Adaptive sequential controller

    DOEpatents

    El-Sharkawi, Mohamed A.; Xing, Jian; Butler, Nicholas G.; Rodriguez, Alonso

    1994-01-01

    An adaptive sequential controller (50/50') for controlling a circuit breaker (52) or other switching device to substantially eliminate transients on a distribution line caused by closing and opening the circuit breaker. The device adaptively compensates for changes in the response time of the circuit breaker due to aging and environmental effects. A potential transformer (70) provides a reference signal corresponding to the zero crossing of the voltage waveform, and a phase shift comparator circuit (96) compares the reference signal to the time at which any transient was produced when the circuit breaker closed, producing a signal indicative of the adaptive adjustment that should be made. Similarly, in controlling the opening of the circuit breaker, a current transformer (88) provides a reference signal that is compared against the time at which any transient is detected when the circuit breaker last opened. An adaptive adjustment circuit (102) produces a compensation time that is appropriately modified to account for changes in the circuit breaker response, including the effect of ambient conditions and aging. When next opened or closed, the circuit breaker is activated at an appropriately compensated time, so that it closes when the voltage crosses zero and opens when the current crosses zero, minimizing any transients on the distribution line. Phase angle can be used to control the opening of the circuit breaker relative to the reference signal provided by the potential transformer.

  4. Adaptive Cruise Control (ACC)

    NASA Astrophysics Data System (ADS)

    Reif, Konrad

    Die adaptive Fahrgeschwindigkeitsregelung (ACC, Adaptive Cruise Control) ist eine Weiterentwicklung der konventionellen Fahrgeschwindigkeitsregelung, die eine konstante Fahrgeschwindigkeit einstellt. ACC überwacht mittels eines Radarsensors den Bereich vor dem Fahrzeug und passt die Geschwindigkeit den Gegebenheiten an. ACC reagiert auf langsamer vorausfahrende oder einscherende Fahrzeuge mit einer Reduzierung der Geschwindigkeit, sodass der vorgeschriebene Mindestabstand zum vorausfahrenden Fahrzeug nicht unterschritten wird. Hierzu greift ACC in Antrieb und Bremse ein. Sobald das vorausfahrende Fahrzeug beschleunigt oder die Spur verlässt, regelt ACC die Geschwindigkeit wieder auf die vorgegebene Sollgeschwindigkeit ein (Bild 1). ACC steht somit für eine Geschwindigkeitsregelung, die sich dem vorausfahrenden Verkehr anpasst.

  5. Adaptive control for accelerators

    DOEpatents

    Eaton, Lawrie E.; Jachim, Stephen P.; Natter, Eckard F.

    1991-01-01

    An adaptive feedforward control loop is provided to stabilize accelerator beam loading of the radio frequency field in an accelerator cavity during successive pulses of the beam into the cavity. A digital signal processor enables an adaptive algorithm to generate a feedforward error correcting signal functionally determined by the feedback error obtained by a beam pulse loading the cavity after the previous correcting signal was applied to the cavity. Each cavity feedforward correcting signal is successively stored in the digital processor and modified by the feedback error resulting from its application to generate the next feedforward error correcting signal. A feedforward error correcting signal is generated by the digital processor in advance of the beam pulse to enable a composite correcting signal and the beam pulse to arrive concurrently at the cavity.

  6. Adaptive nonlinear flight control

    NASA Astrophysics Data System (ADS)

    Rysdyk, Rolf Theoduor

    1998-08-01

    Research under supervision of Dr. Calise and Dr. Prasad at the Georgia Institute of Technology, School of Aerospace Engineering. has demonstrated the applicability of an adaptive controller architecture. The architecture successfully combines model inversion control with adaptive neural network (NN) compensation to cancel the inversion error. The tiltrotor aircraft provides a specifically interesting control design challenge. The tiltrotor aircraft is capable of converting from stable responsive fixed wing flight to unstable sluggish hover in helicopter configuration. It is desirable to provide the pilot with consistency in handling qualities through a conversion from fixed wing flight to hover. The linear model inversion architecture was adapted by providing frequency separation in the command filter and the error-dynamics, while not exiting the actuator modes. This design of the architecture provides for a model following setup with guaranteed performance. This in turn allowed for convenient implementation of guaranteed handling qualities. A rigorous proof of boundedness is presented making use of compact sets and the LaSalle-Yoshizawa theorem. The analysis allows for the addition of the e-modification which guarantees boundedness of the NN weights in the absence of persistent excitation. The controller is demonstrated on the Generic Tiltrotor Simulator of Bell-Textron and NASA Ames R.C. The model inversion implementation is robustified with respect to unmodeled input dynamics, by adding dynamic nonlinear damping. A proof of boundedness of signals in the system is included. The effectiveness of the robustification is also demonstrated on the XV-15 tiltrotor. The SHL Perceptron NN provides a more powerful application, based on the universal approximation property of this type of NN. The SHL NN based architecture is also robustified with the dynamic nonlinear damping. A proof of boundedness extends the SHL NN augmentation with robustness to unmodeled actuator

  7. Adaptations in bilateral mechanical power patterns during obstacle avoidance reveal distinct control strategies for limb elevation versus limb progression.

    PubMed

    Niang, Assane E S; McFadyen, Bradford J

    2004-04-01

    The present study investigated the adaptations of specific power bursts during the combined contexts of the proximity (lead vs. trail limb) and height of an obstruction in relation to limb elevation versus progression. Ten young, adult, male subjects walked at their natural speed during unobstructed walking and the bilateral avoidance of moderate and high obstacles. Hip flexor generation power was unaffected by obstacle height for the leading limb and always delayed for the trailing limb. The knee extensor absorption power burst at toe-off was also eliminated for the trailing limb and was found to reappear in mid-swing. Few differences were seen for ankle push-off power. The results suggest that the hip joint is dedicated to limb advancement only, while the knee joint is directly involved in limb elevation and the control of multiarticular effects.

  8. Adaptive Parent Population Sizing in Evolution Strategies.

    PubMed

    LaPorte, G Jake; Branke, Juergen; Chen, Chun-Hung

    2015-01-01

    Adaptive population sizing aims at improving the overall progress of an evolution strategy. At each generation, it determines the parental population size that promises the largest fitness gain, based on the information collected during the evolutionary process. In this paper, we develop an adaptive variant of a (μ/μ, λ) evolution strategy. Based on considerations on the sphere, we derive two approaches for adaptive population sizing. We then test these approaches empirically on the sphere model using a normalized mutation strength and cumulative mutation strength adaption. Finally, we compare the methodology on more general functions with a fixed population, covariance matrix adaption evolution strategy (CMA-ES). The results confirm that our adaptive population sizing methods yield better results than even the best fixed population size.

  9. An adaptive strategy for active debris removal

    NASA Astrophysics Data System (ADS)

    White, Adam E.; Lewis, Hugh G.

    2014-04-01

    Many parameters influence the evolution of the near-Earth debris population, including launch, solar, explosion and mitigation activities, as well as other future uncertainties such as advances in space technology or changes in social and economic drivers that effect the utilisation of space activities. These factors lead to uncertainty in the long-term debris population. This uncertainty makes it difficult to identify potential remediation strategies, involving active debris removal (ADR), that will perform effectively in all possible future cases. Strategies that cannot perform effectively, because of this uncertainty, risk either not achieving their intended purpose, or becoming a hindrance to the efforts of spacecraft manufactures and operators to address the challenges posed by space debris. One method to tackle this uncertainty is to create a strategy that can adapt and respond to the space debris population. This work explores the concept of an adaptive strategy, in terms of the number of objects required to be removed by ADR, to prevent the low Earth orbit (LEO) debris population from growing in size. This was demonstrated by utilising the University of Southampton’s Debris Analysis and Monitoring Architecture to the Geosynchronous Environment (DAMAGE) tool to investigate ADR rates (number of removals per year) that change over time in response to the current space environment, with the requirement of achieving zero growth of the LEO population. DAMAGE was used to generate multiple Monte Carlo projections of the future LEO debris environment. Within each future projection, the debris removal rate was derived at five-year intervals, by a new statistical debris evolutionary model called the Computational Adaptive Strategy to Control Accurately the Debris Environment (CASCADE) model. CASCADE predicted the long-term evolution of the current DAMAGE population with a variety of different ADR rates in order to identify a removal rate that produced a zero net

  10. Moving from control to elimination of schistosomiasis in sub-Saharan Africa: time to change and adapt strategies.

    PubMed

    Tchuem Tchuenté, Louis-Albert; Rollinson, David; Stothard, J Russell; Molyneux, David

    2017-02-20

    Schistosomiasis is a water borne parasitic disease of global importance and with ongoing control the disease endemic landscape is changing. In sub-Saharan Africa, for example, the landscape is becoming ever more heterogeneous as there are several species of Schistosoma that respond in different ways to ongoing preventive chemotherapy and the inter-sectoral interventions currently applied. The major focus of preventive chemotherapy is delivery of praziquantel by mass drug administration to those shown to be, or presumed to be, at-risk of infection and disease. In some countries, regional progress may be uneven but in certain locations there are very real prospects to transition from control into interruption of transmission, and ultimately elimination. To manage this transition requires reconsideration of some of the currently deployed diagnostic tools used in surveillance and downward realignment of existing prevalence thresholds to trigger mass treatment. A key challenge will be maintaining and if possible, expanding the current donation of praziquantel to currently overlooked groups, then judging when appropriate to move from mass drug administration to selective treatment. In so doing, this will ensure the health system is adapted, primed and shown to be cost-effective to respond to these changing disease dynamics as we move forward to 2020 targets and beyond.

  11. Effective learning strategies for real-time image-guided adaptive control of multiple-source hyperthermia applicators

    PubMed Central

    Cheng, Kung-Shan; Dewhirst, Mark W.; Stauffer, Paul R.; Das, Shiva

    2010-01-01

    Purpose: This paper investigates overall theoretical requirements for reducing the times required for the iterative learning of a real-time image-guided adaptive control routine for multiple-source heat applicators, as used in hyperthermia and thermal ablative therapy for cancer. Methods: Methods for partial reconstruction of the physical system with and without model reduction to find solutions within a clinically practical timeframe were analyzed. A mathematical analysis based on the Fredholm alternative theorem (FAT) was used to compactly analyze the existence and uniqueness of the optimal heating vector under two fundamental situations: (1) noiseless partial reconstruction and (2) noisy partial reconstruction. These results were coupled with a method for further acceleration of the solution using virtual source (VS) model reduction. The matrix approximation theorem (MAT) was used to choose the optimal vectors spanning the reduced-order subspace to reduce the time for system reconstruction and to determine the associated approximation error. Numerical simulations of the adaptive control of hyperthermia using VS were also performed to test the predictions derived from the theoretical analysis. A thigh sarcoma patient model surrounded by a ten-antenna phased-array applicator was retained for this purpose. The impacts of the convective cooling from blood flow and the presence of sudden increase of perfusion in muscle and tumor were also simulated. Results: By FAT, partial system reconstruction directly conducted in the full space of the physical variables such as phases and magnitudes of the heat sources cannot guarantee reconstructing the optimal system to determine the global optimal setting of the heat sources. A remedy for this limitation is to conduct the partial reconstruction within a reduced-order subspace spanned by the first few maximum eigenvectors of the true system matrix. By MAT, this VS subspace is the optimal one when the goal is to maximize the

  12. Advanced Adaptive Optics Control Techniques

    DTIC Science & Technology

    1979-01-01

    Optimal estimation and control methods for high energy laser adaptive optics systems are described. Three system types are examined: Active...the adaptive optics approaches and potential system implementations are recommended.

  13. The development of the Swiss Adaptation Strategy

    NASA Astrophysics Data System (ADS)

    Hohmann, R.; Köllner-Heck, P.; Probst, T.

    2010-09-01

    In summer 2009, the Federal Council mandated the Departement of the Environment, Transport, Energy and Communication (DETEC) to develop a Swiss adaptation strategy. This strategy aims to coordinate the efforts of all federal departments involved in adaptation, and to provide them with the necessary basic information. For the development of the Swiss adaptation strategy the following principles are fundamental. (1.) The strategy aims to achieve the overarching objectives of harnessing the opportunities that climate change presents, minimizing the risks of climate change to people and assets, and to increases the adaptive capacity of all resources. (2) The strategy is based on the most recent scientific knowledge about climate change and climate change impacts. (3.) It is based in on a sound and comprehensive analysis of climate change risks. (4.) It includes strategic goals for the sectors that are most vulnerable to climate change, i.e., water management, biodiversity management, agriculture, forestry, natural hazard prevention, health care, energy generation, tourism, land use. (5.) It thoroughly analyzes the interfaces between the sectoral strategies in order solve existing conflicts and profit form existing synergies. The Swiss Adaptation Strategy will be completed and submitted to the Federal Council by the End of 2011.

  14. Dichotomous Search Strategies for Computerized Adaptive Testing.

    ERIC Educational Resources Information Center

    Xiao, Beiling

    Dichotomous search strategies (DSSs) for computerized adaptive testing are similar to golden section search strategies (GSSSs). Each middle point of successive search regions is a testing point. After each item is administered, the subject's obtained score is compared with the expected score at successive testing points. If the subject's obtained…

  15. Adaptive hybrid control of manipulators

    NASA Technical Reports Server (NTRS)

    Seraji, H.

    1987-01-01

    Simple methods for the design of adaptive force and position controllers for robot manipulators within the hybrid control architecuture is presented. The force controller is composed of an adaptive PID feedback controller, an auxiliary signal and a force feedforward term, and it achieves tracking of desired force setpoints in the constraint directions. The position controller consists of adaptive feedback and feedforward controllers and an auxiliary signal, and it accomplishes tracking of desired position trajectories in the free directions. The controllers are capable of compensating for dynamic cross-couplings that exist between the position and force control loops in the hybrid control architecture. The adaptive controllers do not require knowledge of the complex dynamic model or parameter values of the manipulator or the environment. The proposed control schemes are computationally fast and suitable for implementation in on-line control with high sampling rates.

  16. Adaptive Control of Innate Immunity

    PubMed Central

    Shanker, Anil

    2010-01-01

    1. Summary The mechanisms by which the immune system responds to an infection or disease depend on a complex interplay between the elements of innate and adaptive immunity. While most of the focus so far has been on the innate instruction of the adaptive immune responses, considerable evidence now suggests an equally important adaptive control of the innate immunity. Several studies yield new insights into how the adaptive immunity by initiating an antigen–specific response can compensate, suppress and activate innate responses at the site of tissue antigen. Here we discuss recent advances in our understanding of the adaptive control of immune effector functions in various pathological and physiological conditions. PMID:20394777

  17. Multigrid solution strategies for adaptive meshing problems

    NASA Technical Reports Server (NTRS)

    Mavriplis, Dimitri J.

    1995-01-01

    This paper discusses the issues which arise when combining multigrid strategies with adaptive meshing techniques for solving steady-state problems on unstructured meshes. A basic strategy is described, and demonstrated by solving several inviscid and viscous flow cases. Potential inefficiencies in this basic strategy are exposed, and various alternate approaches are discussed, some of which are demonstrated with an example. Although each particular approach exhibits certain advantages, all methods have particular drawbacks, and the formulation of a completely optimal strategy is considered to be an open problem.

  18. Adaptive control of linearizable systems

    NASA Technical Reports Server (NTRS)

    Sastry, S. Shankar; Isidori, Alberto

    1989-01-01

    Initial results are reported regarding the adaptive control of minimum-phase nonlinear systems which are exactly input-output linearizable by state feedback. Parameter adaptation is used as a technique to make robust the exact cancellation of nonlinear terms, which is called for in the linearization technique. The application of the adaptive technique to control of robot manipulators is discussed. Only the continuous-time case is considered; extensions to the discrete-time and sampled-data cases are not obvious.

  19. Strategies for Computerized Adaptive Grading Testing.

    ERIC Educational Resources Information Center

    Xiao, Beiling

    1999-01-01

    Evaluated three strategies for assigning examinees to grading categories in computerized adaptive testing. The expected a posteriori-based method had more correct classifications in the middle range of grade levels and more errors for the extremes than the golden section search grading test and the Z-score grading test. (SLD)

  20. Strategies for Computerized Adaptive Grading Testing.

    ERIC Educational Resources Information Center

    Xiao, Beiling

    1999-01-01

    Evaluated three strategies for assigning examinees to grading categories in computerized adaptive testing. The expected a posteriori-based method had more correct classifications in the middle range of grade levels and more errors for the extremes than the golden section search grading test and the Z-score grading test. (SLD)

  1. [Adaptation strategies faced with chronic pain].

    PubMed

    Bioy, Antoine

    2017-05-01

    Chronic pain constitutes a challenge for patients. It makes them uneasy with regard to their personality, their corporality and their life balance, and leaves long-lasting effects on their experience as a patient. The development of adaptation strategies and resources to deal with chronic pain is therefore essential. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  2. Avian influenza control strategies

    USDA-ARS?s Scientific Manuscript database

    Control strategies for avian influenza in poultry vary depending on whether the goal is prevention, management, or eradication. Components used in control programs include: 1) education which includes communication, public awareness, and behavioral change, 2) changes to production and marketing sys...

  3. Climate change adaptation strategies and mitigation policies

    NASA Astrophysics Data System (ADS)

    García Fernández, Cristina

    2015-04-01

    The pace of climate change and the consequent warming of the Earth's surface is increasing vulnerability and decreasing adaptive capacity. Achieving a successful adaptation depends on the development of technology, institutional organization, financing availability and the exchange of information. Populations living in arid and semi-arid zones, low-lying coastal areas, land with water shortages or at risk of overflow or small islands are particularly vulnerable to climate change. Due to increasing population density in sensitive areas, some regions have become more vulnerable to events such as storms, floods and droughts, like the river basins and coastal plains. Human activities have fragmented and increased the vulnerability of ecosystems, which limit both, their natural adaptation and the effectiveness of the measures adopted. Adaptation means to carry out the necessary modifications for society to adapt to new climatic conditions in order to reduce their vulnerability to climate change. Adaptive capacity is the ability of a system to adjust to climate change (including climate variability and extremes) and to moderate potential damages, to take advantage of opportunities or face the consequences. Adaptation reduces the adverse impacts of climate change and enhance beneficial impacts, but will not prevent substantial cost that are produced by all damages. The performances require adaptation actions. These are defined and implemented at national, regional or local levels since many of the impacts and vulnerabilities depend on the particular economic, geographic and social circumstances of each country or region. We will present some adaptation strategies at national and local level and revise some cases of its implementation in several vulnerable areas. However, adaptation to climate change must be closely related to mitigation policies because the degree of change planned in different climatic variables is a function of the concentration levels that are achieved

  4. Adaptive velocity strategy for swarm aggregation.

    PubMed

    Li, Wei; Wang, Xiaofan

    2007-02-01

    Collective behaviors of biological swarms have attracted significant interest in recent years, but much attention and efforts have been focused on constant speed models in which all agents are assumed to move with the same constant speed. One limitation of the constant speed assumption without attraction function is that global convergence is quite difficult or even practically impossible to achieve if the speed is relatively fast. In this paper, we propose an adaptive velocity model in which each agent not only adjusts its moving direction but also adjusts its speed according to the degree of direction consensus among its local neighbors. One important feature of the adaptive velocity model is that the speeds of all agents are adaptively tuned to the same maximum constant speed after a short transient process. The adaptive velocity strategy can greatly enhance the global convergence probability, and thus provides a powerful mechanism for coordinated motion in biological and technological multiagent systems.

  5. Aircraft adaptive learning control

    NASA Technical Reports Server (NTRS)

    Lee, P. S. T.; Vanlandingham, H. F.

    1979-01-01

    The optimal control theory of stochastic linear systems is discussed in terms of the advantages of distributed-control systems, and the control of randomly-sampled systems. An optimal solution to longitudinal control is derived and applied to the F-8 DFBW aircraft. A randomly-sampled linear process model with additive process and noise is developed.

  6. Adaptive neural control of spacecraft using control moment gyros

    NASA Astrophysics Data System (ADS)

    Leeghim, Henzeh; Kim, Donghoon

    2015-03-01

    An adaptive control technique is applied to reorient spacecraft with uncertainty using control moment gyros. A nonlinear quaternion feedback law is chosen as a baseline controller. An additional adaptive control input supported by neural networks can estimate and eliminate unknown terms adaptively. The normalized input neural networks are considered for reliable computation of the adaptive input. To prove the stability of the closed-loop dynamics with the control law, the Lyapunov stability theory is considered. Accordingly, the proposed approach results in the uniform ultimate boundedness in tracking error. For reorientation maneuvers, control moment gyros are utilized with a well-known singularity problem described in this work investigated by predicting one-step ahead singularity index. A momentum vector recovery approach using magnetic torquers is also introduced to evaluate the avoidance strategies indirectly. Finally, the suggested methods are demonstrated by numerical simulation studies.

  7. Strategies for adapting to high rates of employee turnover.

    PubMed

    Mowday, R T

    1984-01-01

    For many organizations facing high rates of employee turnover, strategies for increasing employee retention may not be practical because employees leave for reasons beyond the control of management or the costs of reducing turnover exceed the benefits to be derived. In this situation managers need to consider strategies that can minimize or buffer the organization from the negative consequences that often follow from turnover. Strategies organizations can use to adapt to uncontrollably high employee turnover rates are presented in this article. In addition, suggestions are made for how managers should make choices among the alternative strategies.

  8. Adaptation Strategies for Global Environmental Change

    NASA Astrophysics Data System (ADS)

    Ojima, D. S.; Corell, R.

    2007-12-01

    The global environmental challenges society faces today are unheralded due to the pace at which human activities are affecting the earth system. The rates of energy consumption, nitrogen use and production, and water use increases each year leading to greater global environmental changes affecting warming of the earth system and loss of ecosystem services. The challenge we face today as a society is the manner and speed at which we can adapt to these changes affecting the ecosystem services we depend upon. Innovative strategies are needed to develop the adaptive management tools to integrate the sectors and science necessary to deal with the complexity of effects. Developing strategies to better guide decision making related to climate change trends into changing weather patterns at meaningful temporal and spatial scales are needed, observations and prognostic analyses of climate related triggers of threshold events in ecosystem dynamics, and transfer of knowledge between science, technology, and decision makers. These strategies need to better integrate science (physical, biological, and social knowledge), engineering, policy, and economics interests to create a framework to develop strategies for adaptation and mitigation to global change and to create bridges with institutions and organizations that deal with these issues as a governmental agency or private sector enterprise.

  9. Complex adaptive therapeutic strategy (CATS) for cancer.

    PubMed

    Cho, Yong Woo; Kim, Sang Yoon; Kwon, Ick Chan; Kim, In-San

    2014-02-10

    Tumors begin with a single cell, but as each tumor grows and evolves, it becomes a wide collection of clones that display remarkable heterogeneity in phenotypic features, which has posed a big challenge to current targeted anticancer therapy. Intra- and inter-tumoral heterogeneity is attributable in part to genetic mutations but also to adaptation and evolution of tumors to heterogeneity in tumor microenvironments. If tumors are viewed not only as a disease but also as a complex adaptive system (CAS), tumors should be treated as such and a more systemic approach is needed. Some of many tumors therapeutic strategies are discussed here from a view of a tumor as CAS, which can be collectively called a complex adaptive therapeutic strategy (CATS). The central theme of CATS is based on three intermediate concepts: i) disruption of artifacts, ii) disruption of connections, and iii) reprogramming of cancer-immune dynamics. Each strategy presented here is a piece of the puzzle for CATS. Although each piece by itself may be neither novel nor profound, an assembled puzzle could be a novel and innovative cancer therapeutic strategy.

  10. Climate adaptation strategy for natural resources released

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2013-04-01

    The National Fish, Wildlife, and Plants Climate Adaptation Strategy, released on 26 March by the Obama administration, calls for a series of measures to help public and private decision makers better address the effects of climate change on living natural resources. The measures include conserving habitat to support healthy fish, wildlife, and plant populations and ecosystem functions; managing species and habitats to protect ecosystem functions and provide sustainable commercial, subsistence, recreational, and cultural use; increasing knowledge and information about effects on and responses of fish, wildlife, and plants; and reducing nonclimate stressors to help fish, wildlife, plants, and ecosystems adapt.

  11. Adaptive Control Of Remote Manipulator

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun

    1989-01-01

    Robotic control system causes remote manipulator to follow closely reference trajectory in Cartesian reference frame in work space, without resort to computationally intensive mathematical model of robot dynamics and without knowledge of robot and load parameters. System, derived from linear multivariable theory, uses relatively simple feedforward and feedback controllers with model-reference adaptive control.

  12. Nonlinear and adaptive control

    NASA Technical Reports Server (NTRS)

    Athans, Michael

    1989-01-01

    The primary thrust of the research was to conduct fundamental research in the theories and methodologies for designing complex high-performance multivariable feedback control systems; and to conduct feasibiltiy studies in application areas of interest to NASA sponsors that point out advantages and shortcomings of available control system design methodologies.

  13. 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.

  14. Adaptive Strategies for Materials Design using Uncertainties.

    PubMed

    Balachandran, Prasanna V; Xue, Dezhen; Theiler, James; Hogden, John; Lookman, Turab

    2016-01-21

    We compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young's (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material with desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don't. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties.

  15. Simulation analysis of adaptive cruise prediction control

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Cui, Sheng Min

    2017-09-01

    Predictive control is suitable for multi-variable and multi-constraint system control.In order to discuss the effect of predictive control on the vehicle longitudinal motion, this paper establishes the expected spacing model by combining variable pitch spacing and the of safety distance strategy. The model predictive control theory and the optimization method based on secondary planning are designed to obtain and track the best expected acceleration trajectory quickly. Simulation models are established including predictive and adaptive fuzzy control. Simulation results show that predictive control can realize the basic function of the system while ensuring the safety. The application of predictive and fuzzy adaptive algorithm in cruise condition indicates that the predictive control effect is better.

  16. 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.

  17. Adaptive and Nonlinear Control

    DTIC Science & Technology

    1992-02-29

    in [22], we also applied the concept of zero dynamics to the problem of exact linearization of a nonlinear control system by dynamic feedback. Exact ...nonlinear systems, although it was well-known that the conditions for exact linearization are very stringent and consequently do not apply to a broad...29th IEEE Conference n Decision and Control, Invited Paper delivered by Dr. Gilliam. Exact Linearization of Zero Dynamics, 29th IEEE Conference on

  18. An Adaptive Classification Strategy for Reliable Locomotion Mode Recognition.

    PubMed

    Liu, Ming; Zhang, Fan; Huang, He Helen

    2017-09-04

    Algorithms for locomotion mode recognition (LMR) based on surface electromyography and mechanical sensors have recently been developed and could be used for the neural control of powered prosthetic legs. However, the variations in input signals, caused by physical changes at the sensor interface and human physiological changes, may threaten the reliability of these algorithms. This study aimed to investigate the effectiveness of applying adaptive pattern classifiers for LMR. Three adaptive classifiers, i.e., entropy-based adaptation (EBA), LearnIng From Testing data (LIFT), and Transductive Support Vector Machine (TSVM), were compared and offline evaluated using data collected from two able-bodied subjects and one transfemoral amputee. The offline analysis indicated that the adaptive classifier could effectively maintain or restore the performance of the LMR algorithm when gradual signal variations occurred. EBA and LIFT were recommended because of their better performance and higher computational efficiency. Finally, the EBA was implemented for real-time human-in-the-loop prosthesis control. The online evaluation showed that the applied EBA effectively adapted to changes in input signals across sessions and yielded more reliable prosthesis control over time, compared with the LMR without adaptation. The developed novel adaptive strategy may further enhance the reliability of neurally-controlled prosthetic legs.

  19. Design strategies for irregularly adapting parallel applications

    SciTech Connect

    Oliker, Leonid; Biswas, Rupak; Shan, Hongzhang; Sing, Jaswinder Pal

    2000-11-01

    Achieving scalable performance for dynamic irregular applications is eminently challenging. Traditional message-passing approaches have been making steady progress towards this goal; however, they suffer from complex implementation requirements. The use of a global address space greatly simplifies the programming task, but can degrade the performance of dynamically adapting computations. In this work, we examine two major classes of adaptive applications, under five competing programming methodologies and four leading parallel architectures. Results indicate that it is possible to achieve message-passing performance using shared-memory programming techniques by carefully following the same high level strategies. Adaptive applications have computational work loads and communication patterns which change unpredictably at runtime, requiring dynamic load balancing to achieve scalable performance on parallel machines. Efficient parallel implementations of such adaptive applications are therefore a challenging task. This work examines the implementation of two typical adaptive applications, Dynamic Remeshing and N-Body, across various programming paradigms and architectural platforms. We compare several critical factors of the parallel code development, including performance, programmability, scalability, algorithmic development, and portability.

  20. Hybrid adaptive control of a dragonfly model

    NASA Astrophysics Data System (ADS)

    Couceiro, Micael S.; Ferreira, Nuno M. F.; Machado, J. A. Tenreiro

    2012-02-01

    Dragonflies show unique and superior flight performances than most of other insect species and birds. They are equipped with two pairs of independently controlled wings granting an unmatchable flying performance and robustness. In this paper, it is presented an adaptive scheme controlling a nonlinear model inspired in a dragonfly-like robot. It is proposed a hybrid adaptive ( HA) law for adjusting the parameters analyzing the tracking error. At the current stage of the project it is considered essential the development of computational simulation models based in the dynamics to test whether strategies or algorithms of control, parts of the system (such as different wing configurations, tail) as well as the complete system. The performance analysis proves the superiority of the HA law over the direct adaptive ( DA) method in terms of faster and improved tracking and parameter convergence.

  1. 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.

  2. Age-Related Differences in Locomotor Strategies During Adaptive Walking.

    PubMed

    Lowry, Kristin A; Sebastian, Katherine; Perera, Subashan; Van Swearingen, Jessie; Smiley-Oyen, Ann L

    2016-11-21

    Simultaneous control of lower limb stepping movements and trunk motion is important for skilled walking; adapting gait to environmental constraints requires frequent alternations in stepping and trunk motion. These alterations provide a window into the locomotor strategies adopted by the walker. The authors examined gait strategies in young and healthy older adults when manipulating step width. Anteroposterior (AP) and mediolateral (ML) smoothness (quantified by harmonic ratios) and stepping consistency (quantified by gait variability) were analyzed during narrow and wide walking while controlling cadence to preferred pace. Results indicated older adults preserved ML smoothness at the expense of AP smoothness, shortened their steps, and exhibited reduced stepping consistency. The authors conclude that older adults prioritized ML control over forward progression during adaptive walking challenges.

  3. Adaptive Treatment Strategies in Chronic Disease

    PubMed Central

    Lavori, Philip W.; Dawson, Ree

    2009-01-01

    An adaptive treatment strategy (ATS) is a rule for adapting a treatment plan to a patient’s history of previous treatments and the response to those treatments. The ongoing management of chronic disease defines an ATS, which may be implicit and hidden, or explicit and well-specified. The ATS is characterized by the use of intermediate, early markers of response to dynamically alter treatment decisions, in order to achieve a favorable ultimate outcome. We illustrate the concept of ATS with some examples and describe the way that the effect of initial treatment decisions depends on the performance of subsequent decisions at later stages. We show how to compare two or more ATS, or to determine an optimal ATS, using a sequential multiple assignment randomized (SMAR) trial. We observe that clinical trials designers might find the ATS concept useful in improving the efficiency and ecological relevance of clinical trials. PMID:17914924

  4. Adaptive Strategies in the Iterated Exchange Problem

    NASA Astrophysics Data System (ADS)

    Baraov, Arthur

    2011-03-01

    We argue for clear separation of the exchange problem from the exchange paradox to avoid confusion about the subject matter of these two distinct problems. The exchange problem in its current format belongs to the domain of optimal decision making—it doesn't make any sense as a game of competition. But it takes just a tiny modification in the statement of the problem to breathe new life into it and make it a practicable and meaningful game of competition. In this paper, we offer an explanation for paradoxical priors and discuss adaptive strategies for both the house and the player in the restated exchange problem.

  5. Supervisory Control Strategy Development

    SciTech Connect

    Gary D. Storrick; Bojan Petrovic

    2007-02-28

    Task 4 of this collaborative effort between ORNL, Brazil, and Westinghouse for the International Nuclear Energy Research Initiative entitled “Development of Advanced Instrumentation and Control for an Integrated Primary System Reactor” focused on the design of the hierarchical supervisory control for multiple-module units. The state of the IRIS plant design – specifically, the lack of a detailed secondary system design – made developing a detailed hierarchical control difficult at this time. However, other simultaneous and ongoing efforts have contributed to providing the needed information. This report summarizes the results achieved under Task 4 of this Financial Assistance Award. Section 1.2 describes the scope of this effort. Section 2 discusses the IRIS control functions. Next, it briefly reviews the current control concepts, and then reviews the maneuvering requirements for the IRIS plant. It closes by noting the benefits that automated sequences have in reducing operator workload. Section 3 examines reactor loading in the frequency domain to establish some guidelines for module operation, paying particular attention to strategies for using process steam for desalination and/or district heating. The final subsection discusses the implications for reactor control, and argues that using the envisioned percentage (up to 10%) of the NSSS thermal output for these purposes should not significantly affect the NSSS control strategies. Section 4 uses some very general economic assumptions to suggest how one should approach multi-module operation. It concludes that the well-known algorithms used for economic dispatching could be used to help manage a multi-unit IRIS site. Section 5 addresses the human performance factors of multi-module operation. Section 6 summarizes our conclusions.

  6. The 2012 national drug control strategy.

    PubMed

    2013-03-01

    This report is adapted from the Executive Summary and Introduction to the federal national drug control strategy report, which was posted online by the White House in December 2012. Section headings from the full report and brief descriptions of what appears in each section are provided. The full report is posted on the World Wide Web at: http://www.whitehouse.gov/ondcp/2012-national-drug-control-strategy .

  7. Parallel computations and control of adaptive structures

    NASA Technical Reports Server (NTRS)

    Park, K. C.; Alvin, Kenneth F.; Belvin, W. Keith; Chong, K. P. (Editor); Liu, S. C. (Editor); Li, J. C. (Editor)

    1991-01-01

    The equations of motion for structures with adaptive elements for vibration control are presented for parallel computations to be used as a software package for real-time control of flexible space structures. A brief introduction of the state-of-the-art parallel computational capability is also presented. Time marching strategies are developed for an effective use of massive parallel mapping, partitioning, and the necessary arithmetic operations. An example is offered for the simulation of control-structure interaction on a parallel computer and the impact of the approach presented for applications in other disciplines than aerospace industry is assessed.

  8. Adaptive Strategies for Materials Design using Uncertainties

    PubMed Central

    Balachandran, Prasanna V.; Xue, Dezhen; Theiler, James; Hogden, John; Lookman, Turab

    2016-01-01

    We compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young’s (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material with desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don’t. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties. PMID:26792532

  9. Adaptive strategies for materials design using uncertainties

    DOE PAGES

    Balachandran, Prasanna V.; Xue, Dezhen; Theiler, James; ...

    2016-01-21

    Here, we compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young’s (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material withmore » desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don’t. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties.« less

  10. Adaptive strategies for materials design using uncertainties

    SciTech Connect

    Balachandran, Prasanna V.; Xue, Dezhen; Theiler, James; Hogden, John; Lookman, Turab

    2016-01-21

    Here, we compare several adaptive design strategies using a data set of 223 M2AX family of compounds for which the elastic properties [bulk (B), shear (G), and Young’s (E) modulus] have been computed using density functional theory. The design strategies are decomposed into an iterative loop with two main steps: machine learning is used to train a regressor that predicts elastic properties in terms of elementary orbital radii of the individual components of the materials; and a selector uses these predictions and their uncertainties to choose the next material to investigate. The ultimate goal is to obtain a material with desired elastic properties in as few iterations as possible. We examine how the choice of data set size, regressor and selector impact the design. We find that selectors that use information about the prediction uncertainty outperform those that don’t. Our work is a step in illustrating how adaptive design tools can guide the search for new materials with desired properties.

  11. 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.

  12. 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.

  13. 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.

  14. Biometeorology - a science supporting adaptation strategies

    NASA Astrophysics Data System (ADS)

    Matzarakis, A.; Cegnar, T.

    2010-09-01

    Biometeorology as an interdisciplinary science deals with the interactions between atmospheric processes and living organisms (plants, animals and humans). If and in what way weather and climate affect the well-being of all the living creatures? This is the most important question biometeorology is answering. The International Society of Biometeorology (ISB) has built an international forum for the promotion of interdisciplinary collaboration between meteorologists, health professionals, biologists, climatologists, ecologists and other scientists. The Society acts as a community of scientists with similar interests, and fulfills an important role in providing information, expertise and advice for international organizations requiring this assistance. The ISB represents the most comprehensive organization, which brings together people with expertise in these areas. Another specific aim of the ISB is the stimulation of research. Therefore, groups of members are working on several topics organized in commissions for specific targets. The recent five commissions are working in the several fields including climate change issues. Some of examples will be presented, which have been initiated by the members of the ISB and how they can be included as a solid scientific basis to develop efficient adaptation strategies. One such example is a project combining natural and social sciences (in the fields of cooperation processes, tourism analysis and strategy, weather and climate change analysis, information and communication and knowledge transfer) in a transdisciplinary approach that includes players from tourism policy and business and which focuses on the North Sea Coast and the Black Forest. The project "Climate trends and sustainable development of tourism in coastal and mountain range regions was divided into four phases - diagnosis, assessment, strategy/design of solutions, and evaluation - where scientific subprojects and practical partners meet regularly to discuss the

  15. Adaptable state based control system

    NASA Technical Reports Server (NTRS)

    Rasmussen, Robert D. (Inventor); Dvorak, Daniel L. (Inventor); Gostelow, Kim P. (Inventor); Starbird, Thomas W. (Inventor); Gat, Erann (Inventor); Chien, Steve Ankuo (Inventor); Keller, Robert M. (Inventor)

    2004-01-01

    An autonomous controller, comprised of a state knowledge manager, a control executor, hardware proxies and a statistical estimator collaborates with a goal elaborator, with which it shares common models of the behavior of the system and the controller. The elaborator uses the common models to generate from temporally indeterminate sets of goals, executable goals to be executed by the controller. The controller may be updated to operate in a different system or environment than that for which it was originally designed by the replacement of shared statistical models and by the instantiation of a new set of state variable objects derived from a state variable class. The adaptation of the controller does not require substantial modification of the goal elaborator for its application to the new system or environment.

  16. The reduced order model problem in distributed parameter systems adaptive identification and control

    NASA Technical Reports Server (NTRS)

    Johnson, C. R., Jr.

    1980-01-01

    The research concerning the reduced order model problem in distributed parameter systems is reported. The adaptive control strategy was chosen for investigation in the annular momentum control device. It is noted, that if there is no observation spill over, and no model errors, an indirect adaptive control strategy can be globally stable. Recent publications concerning adaptive control are included.

  17. Direct Adaptive Control Of An Industrial Robot

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun; Lee, Thomas; Delpech, Michel

    1992-01-01

    Decentralized direct adaptive control scheme for six-jointed industrial robot eliminates part of overall computational burden imposed by centralized controller and degrades performance of robot by reducing sampling rate. Control and controller-adaptation laws based on observed performance of manipulator: no need to model dynamics of robot. Adaptive controllers cope with uncertainties and variations in robot and payload.

  18. Adaptive robust controller based on integral sliding mode concept

    NASA Astrophysics Data System (ADS)

    Taleb, M.; Plestan, F.

    2016-09-01

    This paper proposes, for a class of uncertain nonlinear systems, an adaptive controller based on adaptive second-order sliding mode control and integral sliding mode control concepts. The adaptation strategy solves the problem of gain tuning and has the advantage of chattering reduction. Moreover, limited information about perturbation and uncertainties has to be known. The control is composed of two parts: an adaptive one whose objective is to reject the perturbation and system uncertainties, whereas the second one is chosen such as the nominal part of the system is stabilised in zero. To illustrate the effectiveness of the proposed approach, an application on an academic example is shown with simulation results.

  19. Adaptive control of a rotating system

    NASA Astrophysics Data System (ADS)

    Dyniewicz, Bartłomiej; Pręgowska, Agnieszka; Bajer, Czesław I.

    2014-02-01

    In the present paper, an adaptive control of structural vibrations is presented. Based on earlier research, we claim that the periodical switching on of magneto-rheological controlled dampers results in the reduction of the amplitudes of vibrations more than does their permanent actuation. This statement, when applied to a moving load problem, was mathematically proved in earlier papers. In the present paper we determine the efficiency of such a control applied to a rotating shaft. The earlier mathematical analysis allows us to propose a control strategy. A finite element simulation together with the solution of the control problem shows that the dampers should act only during a short period of the highest displacements of the structure. The same conclusion is found in experimental tests. Although high frequency control with MR dampers is less efficient than in the theoretical investigations, we have found an amplitude reduction in the range of 10-20%.

  20. Adaptive controller for hyperthermia robot

    SciTech Connect

    Kress, R.L.

    1997-03-01

    This paper describes the development of an adaptive computer control routine for a robotically, deployed focused, ultrasonic hyperthermia cancer treatment system. The control algorithm developed herein uses physiological models of a tumor and the surrounding healthy tissue regions and transient temperature data to estimate the treatment region`s blood perfusion. This estimate is used to vary the specific power profile of a scanned, focused ultrasonic transducer to achieve a temperature distribution as close as possible to an optimal temperature distribution. The controller is evaluated using simulations of diseased tissue and using limited experiments on a scanned, focused ultrasonic treatment system that employs a 5-Degree-of-Freedom (D.O.F.) robot to scan the treatment transducers over a simulated patient. Results of the simulations and experiments indicate that the adaptive control routine improves the temperature distribution over standard classical control algorithms if good (although not exact) knowledge of the treated region is available. Although developed with a scanned, focused ultrasonic robotic treatment system in mind, the control algorithm is applicable to any system with the capability to vary specific power as a function of volume and having an unknown distributed energy sink proportional to temperature elevation (e.g., other robotically deployed hyperthermia treatment methods using different heating modalities).

  1. Adaptive versus nonadaptive strategies for quantum channel discrimination

    SciTech Connect

    Harrow, Aram W.; Hassidim, Avinatan; Leung, Debbie W.; Watrous, John

    2010-03-15

    We provide a simple example that illustrates the advantage of adaptive over nonadaptive strategies for quantum channel discrimination. In particular, we give a pair of entanglement-breaking channels that can be perfectly discriminated by means of an adaptive strategy that requires just two channel evaluations, but for which no nonadaptive strategy can give a perfect discrimination using any finite number of channel evaluations.

  2. Digital adaptive flight controller development

    NASA Technical Reports Server (NTRS)

    Kaufman, H.; Alag, G.; Berry, P.; Kotob, S.

    1974-01-01

    A design study of adaptive control logic suitable for implementation in modern airborne digital flight computers was conducted. Two designs are described for an example aircraft. Each of these designs uses a weighted least squares procedure to identify parameters defining the dynamics of the aircraft. The two designs differ in the way in which control law parameters are determined. One uses the solution of an optimal linear regulator problem to determine these parameters while the other uses a procedure called single stage optimization. Extensive simulation results and analysis leading to the designs are presented.

  3. Chemical process dynamic optimization based on the differential evolution algorithm with an adaptive scheduling mutation strategy

    NASA Astrophysics Data System (ADS)

    Zhu, Jun; Yan, Xuefeng; Zhao, Weixiang

    2013-10-01

    To solve chemical process dynamic optimization problems, a differential evolution algorithm integrated with adaptive scheduling mutation strategy (ASDE) is proposed. According to the evolution feedback information, ASDE, with adaptive control parameters, adopts the round-robin scheduling algorithm to adaptively schedule different mutation strategies. By employing an adaptive mutation strategy and control parameters, the real-time optimal control parameters and mutation strategy are obtained to improve the optimization performance. The performance of ASDE is evaluated using a suite of 14 benchmark functions. The results demonstrate that ASDE performs better than four conventional differential evolution (DE) algorithm variants with different mutation strategies, and that the whole performance of ASDE is equivalent to a self-adaptive DE algorithm variant and better than five conventional DE algorithm variants. Furthermore, ASDE was applied to solve a typical dynamic optimization problem of a chemical process. The obtained results indicate that ASDE is a feasible and competitive optimizer for this kind of problem.

  4. TWO PAPERS ON ADAPTIVE INVENTORY CONTROL.

    DTIC Science & Technology

    INVENTORY CONTROL , ADAPTIVE SYSTEMS), (*DYNAMIC PROGRAMMING, INVENTORY CONTROL ), OPTIMIZATION, COSTS, RANDOM VARIABLES, SAMPLING, MATHEMATICAL PREDICTION, INVENTORY CONTROL , STOCHASTIC PROCESSES, DECISION THEORY

  5. Considering Culturally Relevant Parenting Practices in Intervention Development and Adaptation: A Randomized Controlled Trial of the Black Parenting Strengths and Strategies (BPSS) Program

    ERIC Educational Resources Information Center

    Coard, Stephanie I.; Foy-Watson, Shani; Zimmer, Catherine; Wallace, Amy

    2007-01-01

    A randomized prevention pilot trial compared caregivers who participated in the Black Parenting Strengths and Strategies (BPSS) Program with control caregivers. BPSS is a strengths- and culturally based parenting program designed to improve aspects of parenting associated with the early development of conduct problems and the promotion of social…

  6. Considering Culturally Relevant Parenting Practices in Intervention Development and Adaptation: A Randomized Controlled Trial of the Black Parenting Strengths and Strategies (BPSS) Program

    ERIC Educational Resources Information Center

    Coard, Stephanie I.; Foy-Watson, Shani; Zimmer, Catherine; Wallace, Amy

    2007-01-01

    A randomized prevention pilot trial compared caregivers who participated in the Black Parenting Strengths and Strategies (BPSS) Program with control caregivers. BPSS is a strengths- and culturally based parenting program designed to improve aspects of parenting associated with the early development of conduct problems and the promotion of social…

  7. A Climate Change Adaptation Strategy for Management of ...

    EPA Pesticide Factsheets

    Sea level rise is causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat for fish, shellfish, and wildlife, including species of concern, such as the saltmarsh sparrow (Ammodramus caudacutus). We present a climate change adaptation strategy (CCAS) adopted by scientific, management, and policy stakeholders for managing coastal marshes and enhancing system resiliency. A common adaptive management approach previously used for restoration projects was modified to identify climate-related vulnerabilities and plan climate change adaptive actions. As an example of implementation of the CCAS, we describe the stakeholder plans and management actions the US Fish and Wildlife Service and partners developed to build coastal resiliency in the Narrow River Estuary, RI, in the aftermath of Superstorm Sandy. When possible, an experimental BACI (before-after, control-impact) design, described as pre- and post-sampling at the impact site and one or more control sites, was incorporated into the climate change adaptation and implementation plans. Specific climate change adaptive actions and monitoring plans are described and include shoreline stabilization, restoring marsh drainage, increasing marsh elevation, and enabling upland marsh migration. The CCAS provides a framework and methodology for successfully managing coa

  8. A Climate Change Adaptation Strategy for Management of ...

    EPA Pesticide Factsheets

    Sea level rise is causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat for fish, shellfish, and wildlife, including species of concern, such as the saltmarsh sparrow (Ammodramus caudacutus). We present a climate change adaptation strategy (CCAS) adopted by scientific, management, and policy stakeholders for managing coastal marshes and enhancing system resiliency. A common adaptive management approach previously used for restoration projects was modified to identify climate-related vulnerabilities and plan climate change adaptive actions. As an example of implementation of the CCAS, we describe the stakeholder plans and management actions the US Fish and Wildlife Service and partners developed to build coastal resiliency in the Narrow River Estuary, RI, in the aftermath of Superstorm Sandy. When possible, an experimental BACI (before-after, control-impact) design, described as pre- and post-sampling at the impact site and one or more control sites, was incorporated into the climate change adaptation and implementation plans. Specific climate change adaptive actions and monitoring plans are described and include shoreline stabilization, restoring marsh drainage, increasing marsh elevation, and enabling upland marsh migration. The CCAS provides a framework and methodology for successfully managing coa

  9. Adaptive Force Control in Compliant Motion

    NASA Technical Reports Server (NTRS)

    Seraji, H.

    1994-01-01

    This paper addresses the problem of controlling a manipulator in compliant motion while in contact with an environment having an unknown stiffness. Two classes of solutions are discussed: adaptive admittance control and adaptive compliance control. In both admittance and compliance control schemes, compensator adaptation is used to ensure a stable and uniform system performance.

  10. Keck adaptive optics: control subsystem

    SciTech Connect

    Brase, J.M.; An, J.; Avicola, K.

    1996-03-08

    Adaptive optics on the Keck 10 meter telescope will provide an unprecedented level of capability in high resolution ground based astronomical imaging. The system is designed to provide near diffraction limited imaging performance with Strehl {gt} 0.3 n median Keck seeing of r0 = 25 cm, T =10 msec at 500 nm wavelength. The system will be equipped with a 20 watt sodium laser guide star to provide nearly full sky coverage. The wavefront control subsystem is responsible for wavefront sensing and the control of the tip-tilt and deformable mirrors which actively correct atmospheric turbulence. The spatial sampling interval for the wavefront sensor and deformable mirror is de=0.56 m which gives us 349 actuators and 244 subapertures. This paper summarizes the wavefront control system and discusses particular issues in designing a wavefront controller for the Keck telescope.

  11. Adaptive Controller Effects on Pilot Behavior

    NASA Technical Reports Server (NTRS)

    Trujillo, Anna C.; Gregory, Irene M.; Hempley, Lucas E.

    2014-01-01

    Adaptive control provides robustness and resilience for highly uncertain, and potentially unpredictable, flight dynamics characteristic. Some of the recent flight experiences of pilot-in-the-loop with an adaptive controller have exhibited unpredicted interactions. In retrospect, this is not surprising once it is realized that there are now two adaptive controllers interacting, the software adaptive control system and the pilot. An experiment was conducted to categorize these interactions on the pilot with an adaptive controller during control surface failures. One of the objectives of this experiment was to determine how the adaptation time of the controller affects pilots. The pitch and roll errors, and stick input increased for increasing adaptation time and during the segment when the adaptive controller was adapting. Not surprisingly, altitude, cross track and angle deviations, and vertical velocity also increase during the failure and then slowly return to pre-failure levels. Subjects may change their behavior even as an adaptive controller is adapting with additional stick inputs. Therefore, the adaptive controller should adapt as fast as possible to minimize flight track errors. This will minimize undesirable interactions between the pilot and the adaptive controller and maintain maneuvering precision.

  12. Adaptive-feedback control algorithm.

    PubMed

    Huang, Debin

    2006-06-01

    This paper is motivated by giving the detailed proofs and some interesting remarks on the results the author obtained in a series of papers [Phys. Rev. Lett. 93, 214101 (2004); Phys. Rev. E 71, 037203 (2005); 69, 067201 (2004)], where an adaptive-feedback algorithm was proposed to effectively stabilize and synchronize chaotic systems. This note proves in detail the strictness of this algorithm from the viewpoint of mathematics, and gives some interesting remarks for its potential applications to chaos control & synchronization. In addition, a significant comment on synchronization-based parameter estimation is given, which shows some techniques proposed in literature less strict and ineffective in some cases.

  13. Adaptive limiter control of unimodal population maps.

    PubMed

    Franco, Daniel; Hilker, Frank M

    2013-11-21

    We analyse the adaptive limiter control (ALC) method, which was recently proposed for stabilizing population oscillations and experimentally tested in laboratory populations and metapopulations of Drosophila melanogaster. We thoroughly explain the mechanisms that allow ALC to reduce the magnitude of population fluctuations under certain conditions. In general, ALC is a control strategy with a number of useful properties (e.g. being globally asymptotically stable), but there may be some caveats. The control can be ineffective or even counterproductive at small intensities, and the interventions can be extremely costly at very large intensities. Based on our analytical results, we describe recipes how to choose the control intensity, depending on the range of population sizes we wish to target. In our analysis, we highlight the possible importance of initial transients and classify them into different categories.

  14. Adaptive Flight Control for Aircraft Safety Enhancements

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan T.; Gregory, Irene M.; Joshi, Suresh M.

    2008-01-01

    This poster presents the current adaptive control research being conducted at NASA ARC and LaRC in support of the Integrated Resilient Aircraft Control (IRAC) project. The technique "Approximate Stability Margin Analysis of Hybrid Direct-Indirect Adaptive Control" has been developed at NASA ARC to address the needs for stability margin metrics for adaptive control that potentially enables future V&V of adaptive systems. The technique "Direct Adaptive Control With Unknown Actuator Failures" is developed at NASA LaRC to deal with unknown actuator failures. The technique "Adaptive Control with Adaptive Pilot Element" is being researched at NASA LaRC to investigate the effects of pilot interactions with adaptive flight control that can have implications of stability and performance.

  15. Predictor-Based Model Reference Adaptive Control

    NASA Technical Reports Server (NTRS)

    Lavretsky, Eugene; Gadient, Ross; Gregory, Irene M.

    2010-01-01

    This paper is devoted to the design and analysis of a predictor-based model reference adaptive control. Stable adaptive laws are derived using Lyapunov framework. The proposed architecture is compared with the now classical model reference adaptive control. A simulation example is presented in which numerical evidence indicates that the proposed controller yields improved transient characteristics.

  16. Adaptive Strategy Selection in Decision Making.

    DTIC Science & Technology

    1986-07-31

    s__uc _N__SSEFORE COMLZTM[G FORM . REPORT NUMBER ’ 2. GOVT ACCESSION NO. I RECIP ENT* S CATALOG NUMUER 86-1 V4L_ 𔃾 6 4. TITLE (and Subltl)e. S . TYPE OF...Controlling Office) IS. SECURITY CLASS. (of thle eporl) Unclassified Ia. DECLASSIFICATION/DOWNGRADING S . : SCHEDULE * -F.. I. DISTRIBUTION STATEMENT (ofhis...EDITION OF i NOV 65 IS OBSOLETE S /N 0102- LF- 014. 6601 SECURITY CLASSIFICATION OF THIS PAGE (Mhen bets fntard) efficient strategies for a given

  17. A holistic strategy for adaptive land management

    USDA-ARS?s Scientific Manuscript database

    Adaptive management is widely applied to natural resources management. Adaptive management can be generally defined as an iterative decision-making process that incorporates formulation of management objectives, actions designed to address these objectives, monitoring of results, and repeated adapta...

  18. Can rewiring strategy control the epidemic spreading?

    NASA Astrophysics Data System (ADS)

    Dong, Chao; Yin, Qiuju; Liu, Wenyang; Yan, Zhijun; Shi, Tianyu

    2015-11-01

    Relation existed in the social contact network can affect individuals' behaviors greatly. Considering the diversity of relation intimacy among network nodes, an epidemic propagation model is proposed by incorporating the link-breaking threshold, which is normally neglected in the rewiring strategy. The impact of rewiring strategy on the epidemic spreading in the weighted adaptive network is explored. The results show that the rewiring strategy cannot always control the epidemic prevalence, especially when the link-breaking threshold is low. Meanwhile, as well as strong links, weak links also play a significant role on epidemic spreading.

  19. Adaptation strategies and approaches: Chapter 2

    Treesearch

    Patricia Butler; Chris Swanston; Maria Janowiak; Linda Parker; Matt St. Pierre; Leslie. Brandt

    2012-01-01

    A wealth of information is available on climate change adaptation, but much of it is very broad and of limited use at the finer spatial scales most relevant to land managers. This chapter contains a "menu" of adaptation actions and provides land managers in northern Wisconsin with a range of options to help forest ecosystems adapt to climate change impacts....

  20. Growing assisted migration: Synthesis of a climate change adaptation strategy

    Treesearch

    Mary I. Williams; R. Kasten Dumroese

    2013-01-01

    Assisted migration may be necessary as a climate change adaptation strategy for native plant species that are less adaptive or mobile. Moving plants has been practiced a long time in human history, but movement of species in response to climate change is a new context. First proposed in 1985, assisted migration has gained attention since 2007 as a strategy to prevent...

  1. Control strategies. [of robotic manipulators path

    NASA Technical Reports Server (NTRS)

    Wang, J. C.; Mcinnis, B. C.; Shieh, L. S.

    1988-01-01

    Techniques for improving the performance of robotic-manipulator path-control systems comprising independent SISO feedback controllers for each joint are discussed and illustrated with block diagrams, reviewing the results of recent analytical investigations. Topics examined include the servo design for a single link, the equations of motion for manipulators, SISO servo design for multiple links, inverse methods, pole placement with compensation of the gravity terms, linear state-feedback control based on the perturbation equations, and adaptive control methods. Consideration is given to variable-structure systems, suboptimal controllers, and the optimal-design-strategy approach.

  2. Adapting MCH strategies for the nineties.

    PubMed

    Abel, R

    1994-01-01

    Brief overview was given for strategies in maternal and child health (MCH) in India that were used in the 1980s and adapted for the 1990s in the following areas: perinatal outcomes, empowerment of women, immunization, oral rehydration, adolescent girls, anthropometric measurement, health education, management, and coordination with nongovernmental organizations (NGOs). In order to assure a healthy baby weighing 2.5 kg, monitoring of maternal health is occurring. Iron and folic acid and tetanus toxoid vaccine are provided to pregnant mothers, and fetal growth is monitored. Training of traditional birth attendants and multipurpose health workers will contribute to clean deliveries and referral of complicated pregnancies. During the 1990s, women's health in addition to maternal health has received attention. The empowerment of women to care for themselves, to learn how to mix oral rehydration packets (ORS) at home, and to receive the knowledge and skills were deemed more important than the 1980s focus on the delivery system and inputs of MCH. An excellent cold chain for delivery of vaccines has been put in place, which provides the vehicle for the 1990s to maintain high vaccine coverage. The emphasis on oral rehydration in the 1990s will be on teaching mothers about the importance of ORS treatment of diarrhea. During the 1990s, educating the adolescent girl before she becomes married and pregnant will be the focus. Greater emphasis will be placed on stunting or height for age measurements, as a measure of long term nutritional change; age weight for height for measurement of wasting; and maternal nutritional monitoring of arm circumference. Sustained health education, more media exposure to disease conditions and treatment, and social marketing in health will be better coordinated and more cost effective. Accountability for manpower, materials, and money will be in place within management. Management will focus on motivation and training, and other, newer management

  3. 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.

  4. National Drug Control Strategy, 2011

    ERIC Educational Resources Information Center

    Office of National Drug Control Policy, 2011

    2011-01-01

    In May of 2010, President Obama released the Administration's inaugural "National Drug Control Strategy". Based on the premise that drug use and its consequences pose a threat not just to public safety, but also to public health, the 2010 "Strategy" represented the first comprehensive rebalancing of Federal drug control policy in the nearly 40…

  5. A holistic strategy for adaptive land management

    USGS Publications Warehouse

    Herrick, Jeffrey E.; Duniway, Michael C.; Pyke, David A.; Bestelmeyer, Brandon T.; Wills, Skye A.; Brown, Joel R.; Karl, Jason W.; Havstad, Kris M.

    2012-01-01

    Adaptive management is widely applied to natural resources management (Holling 1973; Walters and Holling 1990). Adaptive management can be generally defined as an iterative decision-making process that incorporates formulation of management objectives, actions designed to address these objectives, monitoring of results, and repeated adaptation of management until desired results are achieved (Brown and MacLeod 1996; Savory and Butterfield 1999). However, adaptive management is often criticized because very few projects ever complete more than one cycle, resulting in little adaptation and little knowledge gain (Lee 1999; Walters 2007). One significant criticism is that adaptive management is often used as a justification for undertaking actions with uncertain outcomes or as a surrogate for the development of specific, measurable indicators and monitoring programs (Lee 1999; Ruhl 2007).

  6. Adapting qualitative research strategies to technology savvy adolescents.

    PubMed

    Mason, Deanna Marie; Ide, Bette

    2014-05-01

    To adapt research strategies involving adolescents in a grounded theory qualitative research study by conducting email rather than face-to-face interviews. Adolescent culture relies heavily on text-based communication and teens prefer interactions mediated through technology. Traditional qualitative research strategies need to be rethought when working with adolescents. Adapting interviewing strategies to electronic environments is timely and relevant for researching adolescents. Twenty three adolescents (aged 16-21) were interviewed by email. A letter of invitation was distributed. Potential participants emailed the researcher to convey interest in participating. If the inclusion criteria were met, email interviews were initiated. Participants controlled the interviews through their rate of response to interview questions. A grounded theory methodology was employed. Initial contact with participants reiterated confidentiality and the ability to withdraw from the study at any time. Interviews began with the collection of demographic information and a broad opening based on a semi-structured interview guide. All data were permissible, including text, photos, music, videos or outside media, for example YouTube. The participant was allowed to give direction to the interview after initial questions were posed. Email interviews continued until saturation was reached in the data. Participants were enthusiastic about email interviewing. Attrition did not occur. Email interviewing gave participants more control over the research, decreased power differentials between the adolescent and researcher, allowed the study to be adapted to cultural, linguistic and developmental needs, and maintained confidentiality. As participants said that email communication was slow and they preferred instant messaging, replication in faster-paced media is recommended. Repetition in face-to-face settings is warranted to evaluate how technology may have influenced the findings. Implications for

  7. Flexible beam control using an adaptive truss

    NASA Technical Reports Server (NTRS)

    Warrington, Thomas J.; Horner, C. Garnett

    1990-01-01

    To demonstrate the feasibility of adaptive trusses for vibration suppression, a 12-ft-long beam is attached to a single cell of an adaptive truss which has three active battens. With the base of the adaptive truss attached to the laboratory frame, the measured strain of the vibrating beam shows the adaptive truss to be very effective in suppressing vibration when subjected to initial conditions. Control is accomplished by a PC/XT computer that implements an LQR-designed control law.

  8. Statistical Physics for Adaptive Distributed Control

    NASA Technical Reports Server (NTRS)

    Wolpert, David H.

    2005-01-01

    A viewgraph presentation on statistical physics for distributed adaptive control is shown. The topics include: 1) The Golden Rule; 2) Advantages; 3) Roadmap; 4) What is Distributed Control? 5) Review of Information Theory; 6) Iterative Distributed Control; 7) Minimizing L(q) Via Gradient Descent; and 8) Adaptive Distributed Control.

  9. Flight Test Approach to Adaptive Control Research

    NASA Technical Reports Server (NTRS)

    Pavlock, Kate Maureen; Less, James L.; Larson, David Nils

    2011-01-01

    The National Aeronautics and Space Administration s Dryden Flight Research Center completed flight testing of adaptive controls research on a full-scale F-18 testbed. The validation of adaptive controls has the potential to enhance safety in the presence of adverse conditions such as structural damage or control surface failures. This paper describes the research interface architecture, risk mitigations, flight test approach and lessons learned of adaptive controls research.

  10. On adaptive modal control of large flexible spacecraft

    NASA Technical Reports Server (NTRS)

    Johnson, C. R., Jr.

    1979-01-01

    A recently developed strategy for adaptive sampled-data control of distributed parameter systems based on a plant modal expansion description and modal simultaneous identification and regulation algorithms is presented with frequent reference to the annular momentum control device (AMCD) test example. The requirements of observation spillover reduction and modal eigenvector shape prespecification, which are especially crucial to the proposed adaptive control strategy, are addressed. Individual low pass time filtering of sensed AMCD particle displacements is proposed for observation spillover reduction. A layered scheme incorporating 'eigenvector' shape improvement is outlined to combat the expansion basis prespecification requirement.

  11. Bed bugs evolved unique adaptive strategy to resist pyrethroid insecticides

    PubMed Central

    Zhu, Fang; Gujar, Hemant; Gordon, Jennifer R.; Haynes, Kenneth F.; Potter, Michael F.; Palli, Subba R.

    2013-01-01

    Recent advances in genomic and post-genomic technologies have facilitated a genome-wide analysis of the insecticide resistance-associated genes in insects. Through bed bug, Cimex lectularius transcriptome analysis, we identified 14 molecular markers associated with pyrethroid resistance. Our studies revealed that most of the resistance-associated genes functioning in diverse mechanisms are expressed in the epidermal layer of the integument, which could prevent or slow down the toxin from reaching the target sites on nerve cells, where an additional layer of resistance (kdr) is possible. This strategy evolved in bed bugs is based on their unique morphological, physiological and behavioral characteristics and has not been reported in any other insect species. RNA interference-aided knockdown of resistance associated genes showed the relative contribution of each mechanism towards overall resistance development. Understanding the complexity of adaptive strategies employed by bed bugs will help in designing the most effective and sustainable bed bug control methods. PMID:23492626

  12. Bed bugs evolved unique adaptive strategy to resist pyrethroid insecticides.

    PubMed

    Zhu, Fang; Gujar, Hemant; Gordon, Jennifer R; Haynes, Kenneth F; Potter, Michael F; Palli, Subba R

    2013-01-01

    Recent advances in genomic and post-genomic technologies have facilitated a genome-wide analysis of the insecticide resistance-associated genes in insects. Through bed bug, Cimex lectularius transcriptome analysis, we identified 14 molecular markers associated with pyrethroid resistance. Our studies revealed that most of the resistance-associated genes functioning in diverse mechanisms are expressed in the epidermal layer of the integument, which could prevent or slow down the toxin from reaching the target sites on nerve cells, where an additional layer of resistance (kdr) is possible. This strategy evolved in bed bugs is based on their unique morphological, physiological and behavioral characteristics and has not been reported in any other insect species. RNA interference-aided knockdown of resistance associated genes showed the relative contribution of each mechanism towards overall resistance development. Understanding the complexity of adaptive strategies employed by bed bugs will help in designing the most effective and sustainable bed bug control methods.

  13. Synthesis of nonlinear adaptive controller for a batch distillation.

    PubMed

    Jana, Amiya K

    2007-02-01

    A nonlinear adaptive control strategy is proposed for a binary batch distillation column. The hybrid control algorithm comprises a generic model controller (GMC) and a nonlinear adaptive state estimator (ASE). The adaptive observation scheme mainly estimates the imprecisely known parameters based on the available tray temperature measurements. The sensitivity of the proposed estimator is investigated with respect to the effect of initialization error, unmeasured disturbance and uncertainty. Then, a comparative study is carried out between the derived nonlinear GMC-ASE controller and a traditional proportional integral law in terms of set point tracking and disturbance rejection performance. The study also includes the effect of measurement noise and parametric uncertainty on the closed-loop performance. The proposed adaptive control algorithm is shown to be quite promising due to the exponential error convergence capability of the ASE estimator in addition to the high-quality control action provided by the GMC controller.

  14. Adaptive, predictive controller for optimal process control

    SciTech Connect

    Brown, S.K.; Baum, C.C.; Bowling, P.S.; Buescher, K.L.; Hanagandi, V.M.; Hinde, R.F. Jr.; Jones, R.D.; Parkinson, W.J.

    1995-12-01

    One can derive a model for use in a Model Predictive Controller (MPC) from first principles or from experimental data. Until recently, both methods failed for all but the simplest processes. First principles are almost always incomplete and fitting to experimental data fails for dimensions greater than one as well as for non-linear cases. Several authors have suggested the use of a neural network to fit the experimental data to a multi-dimensional and/or non-linear model. Most networks, however, use simple sigmoid functions and backpropagation for fitting. Training of these networks generally requires large amounts of data and, consequently, very long training times. In 1993 we reported on the tuning and optimization of a negative ion source using a special neural network[2]. One of the properties of this network (CNLSnet), a modified radial basis function network, is that it is able to fit data with few basis functions. Another is that its training is linear resulting in guaranteed convergence and rapid training. We found the training to be rapid enough to support real-time control. This work has been extended to incorporate this network into an MPC using the model built by the network for predictive control. This controller has shown some remarkable capabilities in such non-linear applications as continuous stirred exothermic tank reactors and high-purity fractional distillation columns[3]. The controller is able not only to build an appropriate model from operating data but also to thin the network continuously so that the model adapts to changing plant conditions. The controller is discussed as well as its possible use in various of the difficult control problems that face this community.

  15. Adaptation and optimal chemotactic strategy for {ital E. coli}

    SciTech Connect

    Strong, S.P.; Bialek, William; Koberle, R. Freedman, B.

    1998-04-01

    Extending the classic works of Berg and Purcell on the biophysics of bacterial chemotaxis, we find the optimal chemotactic strategy for the peritrichous bacterium {ital E. coli} in the high and low signal to noise ratio limits. The optimal strategy depends on properties of the environment and properties of the individual bacterium, and is therefore highly adaptive. We review experiments relevant to testing both the form of the proposed strategy and its adaptability, and propose extensions of them which could test the limits of the adaptability in this simplest sensory processing system. {copyright} {ital 1998} {ital The American Physical Society}

  16. The control of equilibrium in Parkinson's disease patients: delayed adaptation of balancing strategy to shifts in sensory set during a dynamic task.

    PubMed

    De Nunzio, Alessandro M; Nardone, Antonio; Schieppati, Marco

    2007-09-28

    Processing of sensory information, timing operations and set-shifting can be affected in Parkinson's disease (PD) patients. We investigated their capacity and swiftness to pass from a kinaesthetic- to a vision-dependent behaviour during dynamic balancing on a continuously moving support base. Nineteen on-phase PD patients and 13 age-matched normal subjects stood on a platform continuously translating in the antero-posterior direction at 0.2 Hz. Body segment oscillations were identified by a stereophotogrammetric device and electromyogram (EMG) was recorded from tibialis anterior and soleus. Under constant visual conditions, both patients and normal subjects roughly stabilised head and trunk in space with eyes open (EO) but followed the platform displacement with eyes closed (EC). Amplitude and variability of the periodic EMG bursts were smaller with EO than EC. Constant visual-condition trials were intermingled with trials in which subjects opened (EC-EO) or closed (EO-EC) the eyes in response to an acoustic signal. Both patients and normal subjects changed kinematics and EMG patterns to those appropriate for the new visual condition. However, PD patients were slower in changing their behaviour under the EC-EO condition. These findings show abnormal temporal features in balancing strategy adaptation when shifting from kinaesthetic to visual reference in PD. The delay in the implementation of the vision-dependent behaviour was unexpected, given the advantage vision is supposed to confer to motor performance in PD. This condition may play a major role in the instability of patients performing dynamic postural tasks under changing sensory conditions.

  17. Adaptive Control: Actual Status and Trends

    NASA Technical Reports Server (NTRS)

    Landau, I. D.

    1985-01-01

    Important progress in research and application of Adaptive Control Systems has been achieved in the last ten years. The techniques which are currently used in applications will be reviewed. Theoretical aspects currently under investigation and which are related to the application of adaptive control techniques in various fields will be briefly discussed. Applications in various areas will be briefly reviewed. The use of adaptive techniques for vibrations monitoring and active vibration control will be emphasized.

  18. Research in digital adaptive flight controllers

    NASA Technical Reports Server (NTRS)

    Kaufman, H.

    1976-01-01

    A design study of adaptive control logic suitable for implementation in modern airborne digital flight computers was conducted. Both explicit controllers which directly utilize parameter identification and implicit controllers which do not require identification were considered. Extensive analytical and simulation efforts resulted in the recommendation of two explicit digital adaptive flight controllers. Interface weighted least squares estimation procedures with control logic were developed using either optimal regulator theory or with control logic based upon single stage performance indices.

  19. Robust adaptive control for Unmanned Aerial Vehicles

    NASA Astrophysics Data System (ADS)

    Kahveci, Nazli E.

    The objective of meeting higher endurance requirements remains a challenging task for any type and size of Unmanned Aerial Vehicles (UAVs). According to recent research studies significant energy savings can be realized through utilization of thermal currents. The navigation strategies followed across thermal regions, however, are based on rather intuitive assessments of remote pilots and lack any systematic path planning approaches. Various methods to enhance the autonomy of UAVs in soaring applications are investigated while seeking guarantees for flight performance improvements. The dynamics of the aircraft, small UAVs in particular, are affected by the environmental conditions, whereas unmodeled dynamics possibly become significant during aggressive flight maneuvers. Besides, the demanded control inputs might have a magnitude range beyond the limits dictated by the control surface actuators. The consequences of ignoring these issues can be catastrophic. Supporting this claim NASA Dryden Flight Research Center reports considerable performance degradation and even loss of stability in autonomous soaring flight tests with the subsequent risk of an aircraft crash. The existing control schemes are concluded to suffer from limited performance. Considering the aircraft dynamics and the thermal characteristics we define a vehicle-specific trajectory optimization problem to achieve increased cross-country speed and extended range of flight. In an environment with geographically dispersed set of thermals of possibly limited lifespan, we identify the similarities to the Vehicle Routing Problem (VRP) and provide both exact and approximate guidance algorithms for the navigation of automated UAVs. An additional stochastic approach is used to quantify the performance losses due to incorrect thermal data while dealing with random gust disturbances and onboard sensor measurement inaccuracies. One of the main contributions of this research is a novel adaptive control design with

  20. Adaptive Control Techniques for Large Space Structures

    DTIC Science & Technology

    1987-12-23

    mission objectives. In particular, uncertainties in both system dynamics and disturbance spectra characterizations (both time varying and stochastic... uncertainty ) significantly limit the performance attainable with fixed gain, fixed architecture controls. Therefore, the use of an adaptive system , where...Theoretical Development: The initial emphasis has been on slow adaptation, since this covers may LSS situations. Later on we will examine fast adaptation. The

  1. Adaptive Controller Adaptation Time and Available Control Authority Effects on Piloting

    NASA Technical Reports Server (NTRS)

    Trujillo, Anna; Gregory, Irene

    2013-01-01

    Adaptive control is considered for highly uncertain, and potentially unpredictable, flight dynamics characteristic of adverse conditions. This experiment looked at how adaptive controller adaptation time to recover nominal aircraft dynamics affects pilots and how pilots want information about available control authority transmitted. Results indicate that an adaptive controller that takes three seconds to adapt helped pilots when looking at lateral and longitudinal errors. The controllability ratings improved with the adaptive controller, again the most for the three seconds adaptation time while workload decreased with the adaptive controller. The effects of the displays showing the percentage amount of available safe flight envelope used in the maneuver were dominated by the adaptation time. With the displays, the altitude error increased, controllability slightly decreased, and mental demand increased. Therefore, the displays did require some of the subjects resources but these negatives may be outweighed by pilots having more situation awareness of their aircraft.

  2. National Drug Control Strategy. Update

    ERIC Educational Resources Information Center

    Office of National Drug Control Policy, 2005

    2005-01-01

    The first National Drug Control Strategy set ambitious two and five-year performance based goals: (1) to lower the rate of drug use by 10 percent over 2 years among both youth and adults; and (2) to lower the rate by 25 percent over 5 years. The chapters in this updated version are keyed to the strategies three priorities: (1) Stopping Use Before…

  3. National Drug Control Strategy. Update.

    ERIC Educational Resources Information Center

    Office of National Drug Control Policy, Washington, DC.

    President Bush's new National Drug Control Strategy for 2003 focuses on three core priorities: stopping drug use before it starts; healing America's drug users; and disrupting the market. The 2003 strategy reports progress toward meeting the President's goals of reducing drug use by 10 percent over 2 years, and 25 percent over 5 years. With regard…

  4. Heteroresistance at the Single-Cell Level: Adapting to Antibiotic Stress through a Population-Based Strategy and Growth-Controlled Interphenotypic Coordination

    PubMed Central

    Wang, Xiaorong; Kang, Yu; Luo, Chunxiong; Zhao, Tong; Liu, Lin; Jiang, Xiangdan; Fu, Rongrong; An, Shuchang; Chen, Jichao; Jiang, Ning; Ren, Lufeng; Wang, Qi; Baillie, J. Kenneth; Gao, Zhancheng; Yu, Jun

    2014-01-01

    ABSTRACT Heteroresistance refers to phenotypic heterogeneity of microbial clonal populations under antibiotic stress, and it has been thought to be an allocation of a subset of “resistant” cells for surviving in higher concentrations of antibiotic. The assumption fits the so-called bet-hedging strategy, where a bacterial population “hedges” its “bet” on different phenotypes to be selected by unpredicted environment stresses. To test this hypothesis, we constructed a heteroresistance model by introducing a blaCTX-M-14 gene (coding for a cephalosporin hydrolase) into a sensitive Escherichia coli strain. We confirmed heteroresistance in this clone and that a subset of the cells expressed more hydrolase and formed more colonies in the presence of ceftriaxone (exhibited stronger “resistance”). However, subsequent single-cell-level investigation by using a microfluidic device showed that a subset of cells with a distinguishable phenotype of slowed growth and intensified hydrolase expression emerged, and they were not positively selected but increased their proportion in the population with ascending antibiotic concentrations. Therefore, heteroresistance—the gradually decreased colony-forming capability in the presence of antibiotic—was a result of a decreased growth rate rather than of selection for resistant cells. Using a mock strain without the resistance gene, we further demonstrated the existence of two nested growth-centric feedback loops that control the expression of the hydrolase and maximize population growth in various antibiotic concentrations. In conclusion, phenotypic heterogeneity is a population-based strategy beneficial for bacterial survival and propagation through task allocation and interphenotypic collaboration, and the growth rate provides a critical control for the expression of stress-related genes and an essential mechanism in responding to environmental stresses. PMID:24520060

  5. Principles And Applications Of Dual Adaptive Control

    NASA Technical Reports Server (NTRS)

    Mookerjee, Purusottam

    1990-01-01

    Simulations indicate superiority of dual controller over "cautious" controller. Report discusses principles of design of actively adaptive dual controllers. Focus is upon derivation of control laws for dual controller enhancing identification of parameters of mathematical model of multiple-input/multiple-output system, while controlling it at same time. Tasks of identification and control impose competing requirements.

  6. Adaptive control: Myths and realities

    NASA Technical Reports Server (NTRS)

    Athans, M.; Valavani, L.

    1984-01-01

    It was found that all currently existing globally stable adaptive algorithms have three basic properties in common: positive realness of the error equation, square-integrability of the parameter adjustment law and, need for sufficient excitation for asymptotic parameter convergence. Of the three, the first property is of primary importance since it satisfies a sufficient condition for stabillity of the overall system, which is a baseline design objective. The second property has been instrumental in the proof of asymptotic error convergence to zero, while the third addresses the issue of parameter convergence. Positive-real error dynamics can be generated only if the relative degree (excess of poles over zeroes) of the process to be controlled is known exactly; this, in turn, implies perfect modeling. This and other assumptions, such as absence of nonminimum phase plant zeros on which the mathematical arguments are based, do not necessarily reflect properties of real systems. As a result, it is natural to inquire what happens to the designs under less than ideal assumptions. The issues arising from violation of the exact modeling assumption which is extremely restrictive in practice and impacts the most important system property, stability, are discussed.

  7. Adaptive control based on retrospective cost optimization

    NASA Astrophysics Data System (ADS)

    Santillo, Mario A.

    This dissertation studies adaptive control of multi-input, multi-output, linear, time-invariant, discrete-time systems that are possibly unstable and nonminimum phase. We consider both gradient-based adaptive control as well as retrospective-cost-based adaptive control. Retrospective cost optimization is a measure of performance at the current time based on a past window of data and without assumptions about the command or disturbance signals. In particular, retrospective cost optimization acts as an inner loop to the adaptive control algorithm by modifying the performance variables based on the difference between the actual past control inputs and the recomputed past control inputs based on the current control law. We develop adaptive control algorithms that are effective for systems that are nonminimum phase. We consider discrete-time adaptive control since these control laws can be implemented directly in embedded code without requiring an intermediate discretization step. Furthermore, the adaptive controllers in this dissertation are developed under minimal modeling assumptions. In particular, the adaptive controllers require knowledge of the sign of the high-frequency gain and a sufficient number of Markov parameters to approximate the nonminimum-phase zeros (if any). No additional modeling information is necessary. The adaptive controllers presented in this dissertation are developed for full-state-feedback stabilization, static-output-feedback stabilization, as well as dynamic compensation for stabilization, command following, disturbance rejection, and model reference adaptive control. Lyapunov-based stability and convergence proofs are provided for special cases. We present numerical examples to illustrate the algorithms' effectiveness in handling systems that are unstable and/or nonminimum phase and to provide insight into the modeling information required for controller implementation.

  8. Adaptive strategies for cumulative cultural learning.

    PubMed

    Ehn, Micael; Laland, Kevin

    2012-05-21

    The demographic and ecological success of our species is frequently attributed to our capacity for cumulative culture. However, it is not yet known how humans combine social and asocial learning to generate effective strategies for learning in a cumulative cultural context. Here we explore how cumulative culture influences the relative merits of various pure and conditional learning strategies, including pure asocial and social learning, critical social learning, conditional social learning and individual refiner strategies. We replicate the Rogers' paradox in the cumulative setting. However, our analysis suggests that strategies that resolved Rogers' paradox in a non-cumulative setting may not necessarily evolve in a cumulative setting, thus different strategies will optimize cumulative and non-cumulative cultural learning.

  9. Strategies to control trachoma.

    PubMed

    Mathew, Anu A; Turner, Angus; Taylor, Hugh R

    2009-05-29

    Trachoma is a significant public health problem that is endemic in 57 countries, affecting 40.6 million people and contributing to 4% of the global burden of blindness. Repeated episodes of infection from Chlamydia trachomatis lead to long-term inflammation, scarring of the tarsal conjunctiva and distortion of the upper eyelid with in-turning of eyelashes that abrade the surface of the globe. This constant abrasion, in turn, can cause irreversible corneal opacity and blindness. The Alliance for the Global Elimination of Trachoma by 2020 (GET2020) has adopted the SAFE (Surgery, Antibiotics, Facial cleanliness and Environmental improvement) strategy as the main action against trachoma. Trichiasis surgery reduces the risk of blindness by reversing the in-turning of eyelashes and also improves the quality of life from non-visual symptoms. However, future efforts need to aim at increasing accessibility to surgery and improving acceptance. Antibacterials are required to reduce the burden of infection. Oral azithromycin is as close to the perfect antibacterial as we will get for mass distribution: it is safe, requires only a single oral dose, treatment is usually repeated every 6-12 months, resistance is not seen as a problem, and cost is not a limiting factor with a large donation programme and newer generic versions of the drug. Future focus should be on the details of antibacterial distribution such as coverage, frequency of distribution and target population. The promotion of facial cleanliness through education may be the key to trachoma elimination as it will stop the frequent exchange of infected ocular secretions and thus reduce the transmission of infection. However, innovative methods are required to translate health education and promotion activities into sustainable changes in hygiene behaviour. Environmental improvements should focus on the barriers to achieving facial cleanliness and cost-effective means need to be identified. There are a number of countries

  10. The biology of cold hardiness: adaptive strategies

    USDA-ARS?s Scientific Manuscript database

    Characterizing and understanding how plants adapt and acclimate to freezing temperatures during various parts of their life cycle has been the subject of study since the latter part of the 19th century. Each new generation of scientists has used the latest available technology to develop a greater ...

  11. A Methodology for Investigating Adaptive Postural Control

    NASA Technical Reports Server (NTRS)

    McDonald, P. V.; Riccio, G. E.

    1999-01-01

    overt goals. It follows that an essential characteristic of postural behavior is the effective maintenance of the orientation and stability of the sensory and motor "platforms" (e.g., head or shoulders) over variations in the human, the environment and the task. This general skill suggests that individuals should be sensitive to the functional consequences of body configuration and stability. In other words, individuals should perceive the relation between configuration, stability, and performance so that they can adaptively control their interaction with the surroundings. Human-environment interactions constitute robust systems in that individuals can maintain the stability of such interactions over uncertainty about and variations in the dynamics of the interaction. Robust interactions allow individuals to adopt orientations and configurations that are not optimal with respect to purely energetic criteria. Individuals can tolerate variation in postural states, and such variation can serve an important function in adaptive systems. Postural variability generates stimulation which is "textured" by the dynamics of the human-environment system. The texture or structure in stimulation provides information about variation in dynamics, and such information can be sufficient to guide adaption in control strategies. Our method were designed to measure informative patterns of movement variability.

  12. A Methodology for Investigating Adaptive Postural Control

    NASA Technical Reports Server (NTRS)

    McDonald, P. V.; Riccio, G. E.

    1999-01-01

    overt goals. It follows that an essential characteristic of postural behavior is the effective maintenance of the orientation and stability of the sensory and motor "platforms" (e.g., head or shoulders) over variations in the human, the environment and the task. This general skill suggests that individuals should be sensitive to the functional consequences of body configuration and stability. In other words, individuals should perceive the relation between configuration, stability, and performance so that they can adaptively control their interaction with the surroundings. Human-environment interactions constitute robust systems in that individuals can maintain the stability of such interactions over uncertainty about and variations in the dynamics of the interaction. Robust interactions allow individuals to adopt orientations and configurations that are not optimal with respect to purely energetic criteria. Individuals can tolerate variation in postural states, and such variation can serve an important function in adaptive systems. Postural variability generates stimulation which is "textured" by the dynamics of the human-environment system. The texture or structure in stimulation provides information about variation in dynamics, and such information can be sufficient to guide adaption in control strategies. Our method were designed to measure informative patterns of movement variability.

  13. Employee stress management: An examination of adaptive and maladaptive coping strategies on employee health.

    PubMed

    Holton, M Kim; Barry, Adam E; Chaney, J Don

    2015-01-01

    Employees commonly report feeling stressed at work. Examine how employees cope with work and personal stress, whether their coping strategies are adaptive (protective to health) or maladaptive (detrimental to health), and if the manner in which employees cope with stress influences perceived stress management. In this cross-sectional study, a random sample of 2,500 full-time university non-student employees (i.e. faculty, salaried professionals, and hourly non-professionals) were surveyed on health related behaviors including stress and coping. Approximately 1,277 completed the survey (51% ). Hierarchical logistic regression was used to assess the ability of adaptive and maladaptive coping strategies to predict self-reported stress management, while controlling for multiple demographic variables. Over half of employees surveyed reported effective stress management. Most frequently used adaptive coping strategies were communication with friend/family member and exercise, while most frequently used maladaptive coping strategies were drinking alcohol and eating more than usual. Both adaptive and maladaptive coping strategies made significant (p < 0.05) contributions to predicting employee's perceived stress management. Only adaptive coping strategies (B = 0.265) predicted whether someone would self-identify as effectively managing stress. Use of maladaptive coping strategies decreased likelihood of self-reporting effective stress management. Actual coping strategies employed may influence employees' perceived stress management. Adaptive coping strategies may be more influential than maladaptive coping strategies on perceived stress management. Results illustrate themes for effective workplace stress management programs. Stress management programs focused on increasing use of adaptive coping may have a greater impact on employee stress management than those focused on decreasing use of maladaptive coping. Coping is not only a reaction to stressful experiences but also

  14. Control strategies for a telerobot

    NASA Technical Reports Server (NTRS)

    Ohara, John; Stasi, Bill

    1989-01-01

    One of the major issues impacting the utility of telerobotic systems for space is the development of effective control strategies. For near-term applications, telerobot control is likely to utilize teleoperation methodologies with integrated supervisory control capabilities to assist the operator. Two different approaches to telerobotic control are evaluated: bilateral force reflecting master controllers and proportional rate six degrees-of-freedom hand controllers. The controllers' performance of single manipulator arm tasks is compared. Simultaneous operation of both manipulator arms and complex multiaxis slave arm movements is investigated. Task times are significantly longer and fewer errors are committed with the hand controllers. The hand controllers are also rated significantly higher in cognitive and manual control workload on the two-arm task. The master controllers are rated significantly higher in physical workload. The implications of these findings for space teleoperations and higher levels of control are discussed.

  15. Dynamic optimization and adaptive controller design

    NASA Astrophysics Data System (ADS)

    Inamdar, S. R.

    2010-10-01

    In this work I present a new type of controller which is an adaptive tracking controller which employs dynamic optimization for optimizing current value of controller action for the temperature control of nonisothermal continuously stirred tank reactor (CSTR). We begin with a two-state model of nonisothermal CSTR which are mass and heat balance equations and then add cooling system dynamics to eliminate input multiplicity. The initial design value is obtained using local stability of steady states where approach temperature for cooling action is specified as a steady state and a design specification. Later we make a correction in the dynamics where material balance is manipulated to use feed concentration as a system parameter as an adaptive control measure in order to avoid actuator saturation for the main control loop. The analysis leading to design of dynamic optimization based parameter adaptive controller is presented. The important component of this mathematical framework is reference trajectory generation to form an adaptive control measure.

  16. Human Operator Control Strategy Model.

    DTIC Science & Technology

    1980-04-01

    control learning control strategy N computer simulation of motor behavior ABSTRACT (Continue on reverese ide If necesery end Identify by block numbe...Frank Vogler has been a continuing resource during testing and analysis phases. Cooperative Plan students Kirk Hoyer , Bob Baltar, and Bob Hummel have...Introduction ....... .................... .. 79 1. Question 1: Do HOPE models match human behavior to an acceptable extent? .... ............ ... 80

  17. Beyond Brainstorming: Exploring Climate Change Adaptation Strategies

    NASA Astrophysics Data System (ADS)

    Garfin, Gregg; Jacobs, Katharine; Buizer, James

    2008-06-01

    Climate Change Adaptation for Water Managers; Oracle, Arizona, 4-5 February 2008; The most visible manifestation of climate change in the American Southwest is its effects on water resources. Since 1999, the region's water supplies and major rivers have been tested by burgeoning population growth and drought. Model projections suggest increasing drought severity and duration due to rising temperatures, increased evapotranspiration, and enhanced atmospheric circulation from the tropics (Hadley circulation).

  18. Adaptive finite element strategies for shell structures

    NASA Technical Reports Server (NTRS)

    Stanley, G.; Levit, I.; Stehlin, B.; Hurlbut, B.

    1992-01-01

    The present paper extends existing finite element adaptive refinement (AR) techniques to shell structures, which have heretofore been neglected in the AR literature. Specific challenges in applying AR to shell structures include: (1) physical discontinuities (e.g., stiffener intersections); (2) boundary layers; (3) sensitivity to geometric imperfections; (4) the sensitivity of most shell elements to mesh distortion, constraint definition and/or thinness; and (5) intrinsic geometric nonlinearity. All of these challenges but (5) are addressed here.

  19. The Contextual Adaptation of English Teachers' Questioning Strategies

    ERIC Educational Resources Information Center

    Xi, Hong-mei; Li, Wang-zi; Lei, Ping

    2010-01-01

    In order to guarantee an interactive classroom atmosphere, English teachers pay much attention to the questioning strategies when they use question-answer teaching method. This paper makes a comprehensive analysis on English teachers' questioning strategies from the perspective of adaptation theory. It shows that the utilization of teachers'…

  20. Exposure to stressful environments - Strategy of adaptive responses

    NASA Technical Reports Server (NTRS)

    Farhi, Leon E.

    1991-01-01

    Stresses such as hypoxia, water lack, and heat exposure can produce strains in more than a single organ system, in turn stimulating the body to adapt in multiple ways. Nevertheless, a general strategy of the various adaptive responses emerges when the challenges are divided into three groups: (1) conditions that affect the supply of essential molecules, (2) stresses that prevent the body from regulating properly the output of waste products such as CO2 and heat, and (3) environments that disrupt body transport systems. Problems may arise when there is a conflict between two stresses requiring conflicting adaptive changes. An alternative to adaptation, creation of microenvironment, is often favored by the animal.

  1. Exposure to stressful environments - Strategy of adaptive responses

    NASA Technical Reports Server (NTRS)

    Farhi, Leon E.

    1991-01-01

    Stresses such as hypoxia, water lack, and heat exposure can produce strains in more than a single organ system, in turn stimulating the body to adapt in multiple ways. Nevertheless, a general strategy of the various adaptive responses emerges when the challenges are divided into three groups: (1) conditions that affect the supply of essential molecules, (2) stresses that prevent the body from regulating properly the output of waste products such as CO2 and heat, and (3) environments that disrupt body transport systems. Problems may arise when there is a conflict between two stresses requiring conflicting adaptive changes. An alternative to adaptation, creation of microenvironment, is often favored by the animal.

  2. Predictor-Based Model Reference Adaptive Control

    NASA Technical Reports Server (NTRS)

    Lavretsky, Eugene; Gadient, Ross; Gregory, Irene M.

    2009-01-01

    This paper is devoted to robust, Predictor-based Model Reference Adaptive Control (PMRAC) design. The proposed adaptive system is compared with the now-classical Model Reference Adaptive Control (MRAC) architecture. Simulation examples are presented. Numerical evidence indicates that the proposed PMRAC tracking architecture has better than MRAC transient characteristics. In this paper, we presented a state-predictor based direct adaptive tracking design methodology for multi-input dynamical systems, with partially known dynamics. Efficiency of the design was demonstrated using short period dynamics of an aircraft. Formal proof of the reported PMRAC benefits constitute future research and will be reported elsewhere.

  3. Flight Approach to Adaptive Control Research

    NASA Technical Reports Server (NTRS)

    Pavlock, Kate Maureen; Less, James L.; Larson, David Nils

    2011-01-01

    The National Aeronautics and Space Administration's Dryden Flight Research Center completed flight testing of adaptive controls research on a full-scale F-18 testbed. The testbed served as a full-scale vehicle to test and validate adaptive flight control research addressing technical challenges involved with reducing risk to enable safe flight in the presence of adverse conditions such as structural damage or control surface failures. This paper describes the research interface architecture, risk mitigations, flight test approach and lessons learned of adaptive controls research.

  4. Flight Approach to Adaptive Control Research

    NASA Technical Reports Server (NTRS)

    Pavlock, Kate Maureen; Less, James L.; Larson, David Nils

    2011-01-01

    The National Aeronautics and Space Administration's Dryden Flight Research Center completed flight testing of adaptive controls research on a full-scale F-18 testbed. The testbed served as a full-scale vehicle to test and validate adaptive flight control research addressing technical challenges involved with reducing risk to enable safe flight in the presence of adverse conditions such as structural damage or control surface failures. This paper describes the research interface architecture, risk mitigations, flight test approach and lessons learned of adaptive controls research.

  5. Method and apparatus for adaptive force and position control of manipulators

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun (Inventor)

    1995-01-01

    The described and improved multi-arm invention of this application presents three strategies for adaptive control of cooperative multi-arm robots which coordinate control over a common load. In the position-position control strategy, the adaptive controllers ensure that the end-effector positions of both arms track desired trajectories in Cartesian space despite unknown time-varying interaction forces exerted through a load. In the position-hybrid control strategy, the adaptive controller of one arm controls end-effector motions in the free directions and applied forces in the constraint directions; while the adaptive controller of the other arm ensures that the end-effector tracks desired position trajectories. In the hybrid-hybrid control strategy, the adaptive controllers ensure that both end-effectors track reference position trajectories while simultaneously applying desired forces on the load. In all three control strategies, the cross-coupling effects between the arms are treated as disturbances which are compensated for by the adaptive controllers while following desired commands in a common frame of reference. The adaptive controllers do not require the complex mathematical model of the arm dynamics or any knowledge of the arm dynamic parameters or the load parameters such as mass and stiffness. Circuits in the adaptive feedback and feedforward controllers are varied by novel adaptation laws.

  6. Adaptive process control using fuzzy logic and genetic algorithms

    NASA Technical Reports Server (NTRS)

    Karr, C. L.

    1993-01-01

    Researchers at the U.S. Bureau of Mines have developed adaptive process control systems in which genetic algorithms (GA's) are used to augment fuzzy logic controllers (FLC's). GA's are search algorithms that rapidly locate near-optimum solutions to a wide spectrum of problems by modeling the search procedures of natural genetics. FLC's are rule based systems that efficiently manipulate a problem environment by modeling the 'rule-of-thumb' strategy used in human decision making. Together, GA's and FLC's possess the capabilities necessary to produce powerful, efficient, and robust adaptive control systems. To perform efficiently, such control systems require a control element to manipulate the problem environment, and a learning element to adjust to the changes in the problem environment. Details of an overall adaptive control system are discussed. A specific laboratory acid-base pH system is used to demonstrate the ideas presented.

  7. Adaptive Process Control with Fuzzy Logic and Genetic Algorithms

    NASA Technical Reports Server (NTRS)

    Karr, C. L.

    1993-01-01

    Researchers at the U.S. Bureau of Mines have developed adaptive process control systems in which genetic algorithms (GA's) are used to augment fuzzy logic controllers (FLC's). GA's are search algorithms that rapidly locate near-optimum solutions to a wide spectrum of problems by modeling the search procedures of natural genetics. FLC's are rule based systems that efficiently manipulate a problem environment by modeling the 'rule-of-thumb' strategy used in human decision-making. Together, GA's and FLC's possess the capabilities necessary to produce powerful, efficient, and robust adaptive control systems. To perform efficiently, such control systems require a control element to manipulate the problem environment, an analysis element to recognize changes in the problem environment, and a learning element to adjust to the changes in the problem environment. Details of an overall adaptive control system are discussed. A specific laboratory acid-base pH system is used to demonstrate the ideas presented.

  8. Focus on climate projections for adaptation strategies

    NASA Astrophysics Data System (ADS)

    Feijt, Arnout; Appenzeller, Christof; Siegmund, Peter; von Storch, Hans

    2016-01-01

    Most papers in this focus issue on ‘climate and climate impact projections for adaptation strategies’ are solicited by the guest editorial team and originate from a cluster of projects that were initiated 5 years ago. These projects aimed to provide climate change and climate change adaptation information for a wide range of societal areas for the lower parts of the deltas of the Rhine and Meuse rivers, and particularly for the Netherlands. The papers give an overview of our experiences, methods, approaches, results and surprises in the process to developing scientifically underpinned climate products and services for various clients. Although the literature on interactions between society and climate science has grown over the past decade both with respect to policy-science framing in post-normal science (Storch et al 2011 J. Environ. Law Policy 1 1-15, van der Sluijs 2012 Nature and Culture 7 174-195), user-science framing (Berkhout et al 2014 Regional Environ. Change 14 879-93) and joint knowledge production (Hegger et al 2014 Regional Environ. Change 14 1049-62), there is still a lot to gain. With this focus issue we want to contribute to best practices in this quickly moving field between science and society.

  9. Adaptation Strategies of Individuals With Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Roper, Jaimie A.; Terza, Matthew J.; Tillman, Mark D.; Hass, Chris J.

    2016-01-01

    Background: Despite the strong implications for rehabilitation design, the capability of individuals with anterior cruciate ligament reconstruction (ACLR) to adapt and store novel gait patterns have not been well studied. Purpose: To investigate how reconstructive surgery may affect the ability to adapt and store novel gait patterns in persons with ACLR while walking on a split-belt treadmill. Study Design: Controlled laboratory study. Methods: Gait adaptation was compared between 20 participants with ACLR and 20 healthy controls during split-belt treadmill walking. Gait adaptation was assessed in slow- and fast-adapting parameters by (1) the magnitude of symmetry during late adaptation and (2) the amount of the asymmetry during de-adaptation. Results: Healthy individuals adapted a new walking pattern and stored the new walking pattern equally in both the dominant and nondominant limbs. Conversely, individuals with ACLR displayed impairments in both slow-adapting and fast-adapting derived gait adaptation and significant differences in behavior between the reconstructed and uninjured limb. Conclusion: While surgical reconstruction and physical therapy are aimed at improving mechanical stability to the knee, the study data suggest that fundamental features of motor control remain altered. After ACLR, participants display an altered ability to learn and store functional gait patterns. PMID:26894200

  10. Parallel Programming Strategies for Irregular Adaptive Applications

    NASA Technical Reports Server (NTRS)

    Biswas, Rupak; Biegel, Bryan (Technical Monitor)

    2001-01-01

    Achieving scalable performance for dynamic irregular applications is eminently challenging. Traditional message-passing approaches have been making steady progress towards this goal; however, they suffer from complex implementation requirements. The use of a global address space greatly simplifies the programming task, but can degrade the performance for such computations. In this work, we examine two typical irregular adaptive applications, Dynamic Remeshing and N-Body, under competing programming methodologies and across various parallel architectures. The Dynamic Remeshing application simulates flow over an airfoil, and refines localized regions of the underlying unstructured mesh. The N-Body experiment models two neighboring Plummer galaxies that are about to undergo a merger. Both problems demonstrate dramatic changes in processor workloads and interprocessor communication with time; thus, dynamic load balancing is a required component.

  11. The adaptive control system of acetylene generator

    NASA Astrophysics Data System (ADS)

    Kovaliuk, D. O.; Kovaliuk, Oleg; Burlibay, Aron; Gromaszek, Konrad

    2015-12-01

    The method of acetylene production in acetylene generator was analyzed. It was found that impossible to provide the desired process characteristics by the PID-controller. The adaptive control system of acetylene generator was developed. The proposed system combines the classic controller and fuzzy subsystem for controller parameters tuning.

  12. Wireless Control of an LC Adaptive Lens

    NASA Astrophysics Data System (ADS)

    Vdovin, G.; Loktev, M.; Zhang, X.

    We consider using liquid crystal adaptive lenses to correct the accommodation loss and higher-order aberrations of the human eye. In this configuration, the adaptive lens is embedded into the eye lens implant and can be controlled through a wireless inductive link. In this work we experimentally demonstrate a wireless control of a liquid crystal adaptive lens in a wide range of its focusing power by using two coupled coils with the primary coil driven from a low-voltage source through a switching control circuit and the secondary coil used to drive the lens.

  13. Source control strategy accelerates remediation

    SciTech Connect

    Garland, S.B. II; Hammond, R.

    1993-06-01

    Shallow land burial of ion-level radioactive wastes at ORNL has resulted in the release of contaminants into surrounding soil, groundwater, and surface water. Multiple contaminated areas occurring in close proximity make it difficult to relate contaminant releases to a specific site. To address this issue, similar and contiguous contaminated sites within the same drainage area have been combined into Waste Area Groupings. These Waste Area Groupings were prioritized and became the focus of the Comprehensive Environmental Response, Compensation, and Liability Act remediation process. Since the majority of the groupings are in the White Oak Creek drainage basin, the remediation strategy is to control contaminant releases from these source areas first, followed by remediation of White Oak Creek. In planning the remediation program, it became clear that until the issues of ultimate land use and institutional control, waste treatment technologies, and waste disposal facilities are resolved, final remediation objectives cannot be defined and remedial alternatives cannot be evaluated. Consequently, instead of postponing remedial actions until these issues are resolved, a strategy to control the sources of contaminant release with a serie s of interim actions was developed. In the near term, this strategy reduces off-site risk by eliminating contaminant releases and controls on-site risk through institutional control. Source control will allow time to achieve consensus on long-term institutional control and land use issues to develop appropriate treatment technologies, and to construct the necessary disposal facilities without further environmental degradation.

  14. Chaotic satellite attitude control by adaptive approach

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Wang, Jing; Zuo, Min; Liu, Zaiwen; Du, Junping

    2014-06-01

    In this article, chaos control of satellite attitude motion is considered. Adaptive control based on dynamic compensation is utilised to suppress the chaotic behaviour. Control approaches with three control inputs and with only one control input are proposed. Since the adaptive control employed is based on dynamic compensation, faithful model of the system is of no necessity. Sinusoidal disturbance and parameter uncertainties are considered to evaluate the robustness of the closed-loop system. Both of the approaches are confirmed by theoretical and numerical results.

  15. Adaptive nonlinear control for autonomous ground vehicles

    NASA Astrophysics Data System (ADS)

    Black, William S.

    We present the background and motivation for ground vehicle autonomy, and focus on uses for space-exploration. Using a simple design example of an autonomous ground vehicle we derive the equations of motion. After providing the mathematical background for nonlinear systems and control we present two common methods for exactly linearizing nonlinear systems, feedback linearization and backstepping. We use these in combination with three adaptive control methods: model reference adaptive control, adaptive sliding mode control, and extremum-seeking model reference adaptive control. We show the performances of each combination through several simulation results. We then consider disturbances in the system, and design nonlinear disturbance observers for both single-input-single-output and multi-input-multi-output systems. Finally, we show the performance of these observers with simulation results.

  16. Adaptive Flight Control Research at NASA

    NASA Technical Reports Server (NTRS)

    Motter, Mark A.

    2008-01-01

    A broad overview of current adaptive flight control research efforts at NASA is presented, as well as some more detailed discussion of selected specific approaches. The stated objective of the Integrated Resilient Aircraft Control Project, one of NASA s Aviation Safety programs, is to advance the state-of-the-art of adaptive controls as a design option to provide enhanced stability and maneuverability margins for safe landing in the presence of adverse conditions such as actuator or sensor failures. Under this project, a number of adaptive control approaches are being pursued, including neural networks and multiple models. Validation of all the adaptive control approaches will use not only traditional methods such as simulation, wind tunnel testing and manned flight tests, but will be augmented with recently developed capabilities in unmanned flight testing.

  17. Design and research of adaptive control of purification process of biotrickling bed for VOC waste gas

    NASA Astrophysics Data System (ADS)

    Hu, Xin-Yu; Zhao, Ming-Fu; Luo, Kai; Luo, Bin-Bin; Ling, Wen-Hao

    2008-10-01

    Based on visualization test of biotrickling bed, we analyze the dynamicmodel of the purification process, and get the dynamic model on liquid flux and purification efficiency. The adaptive control strategy is applied in the purification process. The simulation test proves that under the same disturbance the adaptive control strategy is more effective than PID.

  18. Global isotope metabolomics reveals adaptive strategies for nitrogen assimilation

    DOE PAGES

    Kurczy, Michael E.; Forsberg, Erica M.; Thorgersen, Michael P.; ...

    2016-04-05

    Nitrogen cycling is a microbial metabolic process essential for global ecological/agricultural balance. To investigate the link between the well-established ammonium and the alternative nitrate assimilation metabolic pathways, global isotope metabolomics was employed to examine three nitrate reducing bacteria using 15NO3 as a nitrogen source. In contrast to a control (Pseudomonas stutzeri RCH2), the results show that two of the isolates from Oak Ridge, Tennessee (Pseudomonas N2A2 and N2E2) utilize nitrate and ammonia for assimilation concurrently with differential labeling observed across multiple classes of metabolites including amino acids and nucleotides. The data reveal that the N2A2 and N2E2 strains conserve nitrogen-containingmore » metabolites, indicating that the nitrate assimilation pathway is a conservation mechanism for the assimilation of nitrogen. Co-utilization of nitrate and ammonia is likely an adaption to manage higher levels of nitrite since the denitrification pathways utilized by the N2A2 and N2E2 strains from the Oak Ridge site are predisposed to the accumulation of the toxic nitrite. In conclusion, the use of global isotope metabolomics allowed for this adaptive strategy to be investigated, which would otherwise not have been possible to decipher.« less

  19. Global isotope metabolomics reveals adaptive strategies for nitrogen assimilation

    SciTech Connect

    Kurczy, Michael E.; Forsberg, Erica M.; Thorgersen, Michael P.; Poole, Farris L.; Benton, H. Paul; Ivanisevic, Julijana; Tran, Minerva L.; Wall, Judy D.; Elias, Dwayne A.; Adams, Michael W. W.; Siuzdak, Gary

    2016-04-05

    Nitrogen cycling is a microbial metabolic process essential for global ecological/agricultural balance. To investigate the link between the well-established ammonium and the alternative nitrate assimilation metabolic pathways, global isotope metabolomics was employed to examine three nitrate reducing bacteria using 15NO3 as a nitrogen source. In contrast to a control (Pseudomonas stutzeri RCH2), the results show that two of the isolates from Oak Ridge, Tennessee (Pseudomonas N2A2 and N2E2) utilize nitrate and ammonia for assimilation concurrently with differential labeling observed across multiple classes of metabolites including amino acids and nucleotides. The data reveal that the N2A2 and N2E2 strains conserve nitrogen-containing metabolites, indicating that the nitrate assimilation pathway is a conservation mechanism for the assimilation of nitrogen. Co-utilization of nitrate and ammonia is likely an adaption to manage higher levels of nitrite since the denitrification pathways utilized by the N2A2 and N2E2 strains from the Oak Ridge site are predisposed to the accumulation of the toxic nitrite. In conclusion, the use of global isotope metabolomics allowed for this adaptive strategy to be investigated, which would otherwise not have been possible to decipher.

  20. Global Isotope Metabolomics Reveals Adaptive Strategies for Nitrogen Assimilation.

    PubMed

    Kurczy, Michael E; Forsberg, Erica M; Thorgersen, Michael P; Poole, Farris L; Benton, H Paul; Ivanisevic, Julijana; Tran, Minerva L; Wall, Judy D; Elias, Dwayne A; Adams, Michael W W; Siuzdak, Gary

    2016-06-17

    Nitrogen cycling is a microbial metabolic process essential for global ecological/agricultural balance. To investigate the link between the well-established ammonium and the alternative nitrate assimilation metabolic pathways, global isotope metabolomics was employed to examine three nitrate reducing bacteria using (15)NO3 as a nitrogen source. In contrast to a control (Pseudomonas stutzeri RCH2), the results show that two of the isolates from Oak Ridge, Tennessee (Pseudomonas N2A2 and N2E2) utilize nitrate and ammonia for assimilation concurrently with differential labeling observed across multiple classes of metabolites including amino acids and nucleotides. The data reveal that the N2A2 and N2E2 strains conserve nitrogen-containing metabolites, indicating that the nitrate assimilation pathway is a conservation mechanism for the assimilation of nitrogen. Co-utilization of nitrate and ammonia is likely an adaption to manage higher levels of nitrite since the denitrification pathways utilized by the N2A2 and N2E2 strains from the Oak Ridge site are predisposed to the accumulation of the toxic nitrite. The use of global isotope metabolomics allowed for this adaptive strategy to be investigated, which would otherwise not have been possible to decipher.

  1. Learning optimal adaptation strategies in unpredictable motor tasks

    PubMed Central

    Braun, D. A.; Aertsen, A.; Wolpert, D. M.; Mehring, C.

    2009-01-01

    Picking up an empty milk carton that we believe to be full is a familiar example of adaptive control, because the adaptation process of estimating the carton's weight must proceed simultaneously to the control process of moving the carton to a desired location. Here we show that the motor system initially generates highly variable behavior in such unpredictable tasks but eventually converges to stereotyped patterns of adaptive responses predicted by a simple optimality principle. These results suggest that adaptation can become specifically tuned to identify task-specific parameters in an optimal manner. PMID:19458218

  2. National Drug Control Strategy, 2006

    ERIC Educational Resources Information Center

    The White House, 2006

    2006-01-01

    This report presents a summary of the Fiscal Year 2007 Budget for the National Drug Control Strategy within the three key priority areas; education and community action, treatment and intervention, and disruption in the illegal drug market. The first chapter, "Stopping Drug Use Before It Starts," outlines the Administration's work to prevent the…

  3. Controlling viral outbreaks: Quantitative strategies

    PubMed Central

    2017-01-01

    Preparing for and responding to outbreaks of serious livestock infectious diseases are critical measures to safeguard animal health, public health, and food supply. Almost all of the current control strategies are empirical, and mass culling or “stamping out” is frequently the principal strategy for controlling epidemics. However, there are ethical, ecological, and economic reasons to consider less drastic control strategies. Here we use modeling to quantitatively study the efficacy of different control measures for viral outbreaks, where the infectiousness, transmissibility and death rate of animals commonly depends on their viral load. We develop a broad theoretical framework for exploring and understanding this heterogeneity. The model includes both direct transmission from infectious animals and indirect transmission from an environmental reservoir. We then incorporate a large variety of control measures, including vaccination, antivirals, isolation, environmental disinfection, and several forms of culling, which may result in fewer culled animals. We provide explicit formulae for the basic reproduction number, R0, for each intervention and for combinations. We evaluate the control methods for a realistic simulated outbreak of low pathogenic avian influenza on a mid-sized turkey farm. In this simulated outbreak, culling results in more total dead birds and dramatically more when culling all of the infected birds. PMID:28187137

  4. Adaptive control for payload launch vibration isolation

    NASA Astrophysics Data System (ADS)

    Jarosh, Julian R.; Agnes, Gregory S.; Karahalis, Gregory G.

    2001-07-01

    The Department of Defense has identified launch vibration isolation as a major research interest. Reducing the loads a satellite experiences during launch will greatly enhance the reliability and lifetime and decrease the payload structural mass. DoD space programs stand to benefit significantly from advances in vibration isolation technology. This study explores potential hybrid vibration isolation using adaptive control with a passive isolator. Lyapunov analysis is used to develop the structural adaptive control scheme. Simulink and Matlab simulations investigate these control methodologies on a lumped mass dynamic model of a satellite and its representative launch vehicle. The results are compared to Proportional-Integral-Derivative (PID) control and skyhook damper active control methods. The results of the modeling indicate adaptive control achieves up to a 90 percent reduction in loads on the payload when compared to the conventional active control methods. The adaptive controller compensated for the loads being transmitted to the payload from the rest of the launch vehicle. The current adaptive controller was not able to effectively control the motion of a vibrating subcomponent within the payload or the subcomponent's effect on the overall payload itself.

  5. Decentralized digital adaptive control of robot motion

    NASA Technical Reports Server (NTRS)

    Tarokh, M.

    1990-01-01

    A decentralized model reference adaptive scheme is developed for digital control of robot manipulators. The adaptation laws are derived using hyperstability theory, which guarantees asymptotic trajectory tracking despite gross robot parameter variations. The control scheme has a decentralized structure in the sense that each local controller receives only its joint angle measurement to produce its joint torque. The independent joint controllers have simple structures and can be programmed using a very simple and computationally fast algorithm. As a result, the scheme is suitable for real-time motion control.

  6. Adaptive strategy for the statistical analysis of connectomes.

    PubMed

    Meskaldji, Djalel Eddine; Ottet, Marie-Christine; Cammoun, Leila; Hagmann, Patric; Meuli, Reto; Eliez, Stephan; Thiran, Jean Philippe; Morgenthaler, Stephan

    2011-01-01

    We study an adaptive statistical approach to analyze brain networks represented by brain connection matrices of interregional connectivity (connectomes). Our approach is at a middle level between a global analysis and single connections analysis by considering subnetworks of the global brain network. These subnetworks represent either the inter-connectivity between two brain anatomical regions or by the intra-connectivity within the same brain anatomical region. An appropriate summary statistic, that characterizes a meaningful feature of the subnetwork, is evaluated. Based on this summary statistic, a statistical test is performed to derive the corresponding p-value. The reformulation of the problem in this way reduces the number of statistical tests in an orderly fashion based on our understanding of the problem. Considering the global testing problem, the p-values are corrected to control the rate of false discoveries. Finally, the procedure is followed by a local investigation within the significant subnetworks. We contrast this strategy with the one based on the individual measures in terms of power. We show that this strategy has a great potential, in particular in cases where the subnetworks are well defined and the summary statistics are properly chosen. As an application example, we compare structural brain connection matrices of two groups of subjects with a 22q11.2 deletion syndrome, distinguished by their IQ scores.

  7. [Optimal personal resource as a determinant of adaptational strategies of shift workers in Far North].

    PubMed

    Korneyeva, Ya A; Simonova, N N; Degteva, G N

    2015-01-01

    Development of mineral deposits in Far North and Arctic regions is a priority in Russian Federation. Result of shift workers' adaptation in Far North is formed adaptational strategy. Environmental and personal resources determine adaptational strategies in occupational activity of shift workers. Optimal personal resource of adaptational strategies in shift workers is: acceptance of others, moderate internality, integral adaptation value and programming as regulatory process.

  8. Stepping strategies for regulating gait adaptability and stability.

    PubMed

    Hak, Laura; Houdijk, Han; Steenbrink, Frans; Mert, Agali; van der Wurff, Peter; Beek, Peter J; van Dieën, Jaap H

    2013-03-15

    Besides a stable gait pattern, gait in daily life requires the capability to adapt this pattern in response to environmental conditions. The purpose of this study was to elucidate the anticipatory strategies used by able-bodied people to attain an adaptive gait pattern, and how these strategies interact with strategies used to maintain gait stability. Ten healthy subjects walked in a Computer Assisted Rehabilitation ENvironment (CAREN). To provoke an adaptive gait pattern, subjects had to hit virtual targets, with markers guided by their knees, while walking on a self-paced treadmill. The effects of walking with and without this task on walking speed, step length, step frequency, step width and the margins of stability (MoS) were assessed. Furthermore, these trials were performed with and without additional continuous ML platform translations. When an adaptive gait pattern was required, subjects decreased step length (p<0.01), tended to increase step width (p=0.074), and decreased walking speed while maintaining similar step frequency compared to unconstrained walking. These adaptations resulted in the preservation of equal MoS between trials, despite the disturbing influence of the gait adaptability task. When the gait adaptability task was combined with the balance perturbation subjects further decreased step length, as evidenced by a significant interaction between both manipulations (p=0.012). In conclusion, able-bodied people reduce step length and increase step width during walking conditions requiring a high level of both stability and adaptability. Although an increase in step frequency has previously been found to enhance stability, a faster movement, which would coincide with a higher step frequency, hampers accuracy and may consequently limit gait adaptability.

  9. Interactive spatial tools for the design of regional adaptation strategies.

    PubMed

    Eikelboom, T; Janssen, R

    2013-09-01

    Regional adaptation strategies are plans that consist of feasible measures to shift a region towards a system that is flexible and robust for future climate changes. They apply to regional impacts of climate change and are imbedded in broader planning. Multiple adaptation frameworks and guidelines exist that describe the development stages of regional adaptation strategies. Spatial information plays a key role in the design of adaptation measures as both the effects of climate change as well as many adaptation measures have spatial impacts. Interactive spatial support tools such as drawing, simulation and evaluation tools can assist the development process. This paper presents how to connect tasks derived from the actual development stages to spatial support tools in an interactive multi-stakeholder context. This link helps to decide what spatial tools are suited to support which stages in the development process of regional adaptation strategies. The practical implication of the link is illustrated for three case study workshops in the Netherlands. The regional planning workshops combine expertise from both scientists and stakeholders with an interactive mapping device. This approach triggered participants to share their expertise and stimulated integration of knowledge. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Adaptive Through-Thickness Integration Strategy for Shell Elements

    NASA Astrophysics Data System (ADS)

    Burchitz, I. A.; Meinders, T.; Huétink, J.

    2007-05-01

    Reliable numerical prediction of springback in sheet metal forming is essential for the automotive industry. There are numerous factors that influence the accuracy of springback prediction by using the finite element method. One of the reasons is the through-thickness numerical integration of shell elements. It is known that even for simple problems the traditional integration schemes may require up to 50 integration points to achieve a high accuracy of springback analysis. An adaptive through-thickness integration strategy can be a good alternative. The strategy defines abscissas and weights depending on the integrand's properties and, thus, can adapt itself to improve the accuracy of integration. A concept of the adaptive through-thickness integration strategy for shell elements is presented. It is tested using a simple problem of bending of a beam under tension. Results show that for a similar set of material and process parameters the adaptive Simpson's rule with 7 integration points performs better than the traditional trapezoidal rule with 50 points. The adaptive through-thickness integration strategy for shell elements can improve the accuracy of springback prediction at minimal costs.

  11. On Fractional Model Reference Adaptive Control

    PubMed Central

    Shi, Bao; Dong, Chao

    2014-01-01

    This paper extends the conventional Model Reference Adaptive Control systems to fractional ones based on the theory of fractional calculus. A control law and an incommensurate fractional adaptation law are designed for the fractional plant and the fractional reference model. The stability and tracking convergence are analyzed using the frequency distributed fractional integrator model and Lyapunov theory. Moreover, numerical simulations of both linear and nonlinear systems are performed to exhibit the viability and effectiveness of the proposed methodology. PMID:24574897

  12. Control Strategies to Achieve Air Pollution Reduction

    EPA Pesticide Factsheets

    Considerations in designing an effective control strategy related to air quality, controlling pollution sources, need for regional or national controls, steps to developing a control strategy, and additional EPA resources.

  13. Analysis of pilot control strategy

    NASA Technical Reports Server (NTRS)

    Heffley, R. K.; Hanson, G. D.; Jewell, W. F.; Clement, W. F.

    1983-01-01

    Methods for nonintrusive identification of pilot control strategy and task execution dynamics are presented along with examples based on flight data. The specific analysis technique is Nonintrusive Parameter Identification Procedure (NIPIP), which is described in a companion user's guide (NASA CR-170398). Quantification of pilot control strategy and task execution dynamics is discussed in general terms followed by a more detailed description of how NIPIP can be applied. The examples are based on flight data obtained from the NASA F-8 digital fly by wire airplane. These examples involve various piloting tasks and control axes as well as a demonstration of how the dynamics of the aircraft itself are identified using NIPIP. Application of NIPIP to the AFTI/F-16 flight test program is discussed. Recommendations are made for flight test applications in general and refinement of NIPIP to include interactive computer graphics.

  14. Adaptive mesh strategies for the spectral element method

    NASA Technical Reports Server (NTRS)

    Mavriplis, Catherine

    1992-01-01

    An adaptive spectral method was developed for the efficient solution of time dependent partial differential equations. Adaptive mesh strategies that include resolution refinement and coarsening by three different methods are illustrated on solutions to the 1-D viscous Burger equation and the 2-D Navier-Stokes equations for driven flow in a cavity. Sharp gradients, singularities, and regions of poor resolution are resolved optimally as they develop in time using error estimators which indicate the choice of refinement to be used. The adaptive formulation presents significant increases in efficiency, flexibility, and general capabilities for high order spectral methods.

  15. Adaptive control of closed-circuit anesthesia.

    PubMed

    Vishnoi, R; Roy, R J

    1991-01-01

    Closed-circuit anesthesia (CCA) is more economical and ecologically safer than open circuit anesthesia. However, gas concentrations are more difficult to control. Computer control of CCA has been proposed to facilitate its use. Past efforts have either been limited to the control of anesthetic gas concentrations or apply only to a small group of patients. This paper describes a comprehensive control system applicable to a large class of patients. This system controls the end-tidal oxygen and anesthetic gas concentrations, and the circuit volume. The CCA process was modeled by writing mass balance equations. Simplifying assumptions yielded a bilinear single-input-single-output model for the anesthetic gas concentration and a bilinear multiple-input-multiple-output model for the circuit volume and oxygen concentration. One-step-ahead controllers were used to control these two subsystems. Simulations showed that the control performance was most sensitive to the gas uptakes. Three independent, least-mean-squares estimation schemes were implemented to estimate the uptakes of oxygen, nitrous oxide, and anesthetic gas. These estimates were used in the control law and resulted in explicit adaptive control. The performance of the adaptive controller was compared to that of a fixed controller (with precalculated gas uptakes) in five animal experiments. The adaptive controller performed better than the fixed controller in all cases. The most significant difference was in the anesthetic gas response time 3.6 +/- 0.70 min for adaptive control and 7.04 +/- 5.62 min for fixed control. The adaptive controller was also robust with respect to variations in the system parameters such as the functional residual capacity, leak, deadspace and gas uptakes.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Optimal strategies for adaptive curve lighting.

    PubMed

    Sivak, Michael; Schoettle, Brandon; Flannagan, Michael J; Minoda, Takako

    2005-01-01

    Conventional low beams headlamps do not provide sufficient illumination for nighttime visibility on curves. This analytical study evaluated the advantages and disadvantages of several curve-lighting strategies that involve moving one or both low beams by various amounts. Two curve radii were examined for both curve directions, using representative tungsten-halogen and high-intensity discharge low-beam patterns. The dependent variable was the maximum distance of 3-lux illumination (combined from both lamps) at a plane 0.25 m above the roadway for seven lateral positions. For short-radius, left and right curves, moving both lamps in parallel should substantially increase the visibility of objects in one's lane of travel, in several additional lanes of travel to the left and right, and off the road. Because of the lateral trade-offs of advantages and disadvantages for large-radius curves, additional research is needed to better understand the desirable approach for these types of curves. Moving both lamps in parallel into the curve is recommended for small-radius curves.

  17. Adaptive Control for Microgravity Vibration Isolation System

    NASA Technical Reports Server (NTRS)

    Yang, Bong-Jun; Calise, Anthony J.; Craig, James I.; Whorton, Mark S.

    2005-01-01

    Most active vibration isolation systems that try to a provide quiescent acceleration environment for space science experiments have utilized linear design methods. In this paper, we address adaptive control augmentation of an existing classical controller that employs a high-gain acceleration feedback together with a low-gain position feedback to center the isolated platform. The control design feature includes parametric and dynamic uncertainties because the hardware of the isolation system is built as a payload-level isolator, and the acceleration Sensor exhibits a significant bias. A neural network is incorporated to adaptively compensate for the system uncertainties, and a high-pass filter is introduced to mitigate the effect of the measurement bias. Simulations show that the adaptive control improves the performance of the existing acceleration controller and keep the level of the isolated platform deviation to that of the existing control system.

  18. An Optimal Control Modification to Model-Reference Adaptive Control for Fast Adaptation

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan T.; Krishnakumar, Kalmanje; Boskovic, Jovan

    2008-01-01

    This paper presents a method that can achieve fast adaptation for a class of model-reference adaptive control. It is well-known that standard model-reference adaptive control exhibits high-gain control behaviors when a large adaptive gain is used to achieve fast adaptation in order to reduce tracking error rapidly. High gain control creates high-frequency oscillations that can excite unmodeled dynamics and can lead to instability. The fast adaptation approach is based on the minimization of the squares of the tracking error, which is formulated as an optimal control problem. The necessary condition of optimality is used to derive an adaptive law using the gradient method. This adaptive law is shown to result in uniform boundedness of the tracking error by means of the Lyapunov s direct method. Furthermore, this adaptive law allows a large adaptive gain to be used without causing undesired high-gain control effects. The method is shown to be more robust than standard model-reference adaptive control. Simulations demonstrate the effectiveness of the proposed method.

  19. A multiple pointing-mount control strategy for space platforms

    NASA Technical Reports Server (NTRS)

    Johnson, C. D.

    1992-01-01

    A new disturbance-adaptive control strategy for multiple pointing-mount space platforms is proposed and illustrated by consideration of a simplified 3-link dynamic model of a multiple pointing-mount space platform. Simulation results demonstrate the effectiveness of the new platform control strategy. The simulation results also reveal a system 'destabilization phenomena' that can occur if the set of individual platform-mounted experiment controllers are 'too responsive.'

  20. 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.

  1. Adaptive suboptimal second-order sliding mode control for microgrids

    NASA Astrophysics Data System (ADS)

    Incremona, Gian Paolo; Cucuzzella, Michele; Ferrara, Antonella

    2016-09-01

    This paper deals with the design of adaptive suboptimal second-order sliding mode (ASSOSM) control laws for grid-connected microgrids. Due to the presence of the inverter, of unpredicted load changes, of switching among different renewable energy sources, and of electrical parameters variations, the microgrid model is usually affected by uncertain terms which are bounded, but with unknown upper bounds. To theoretically frame the control problem, the class of second-order systems in Brunovsky canonical form, characterised by the presence of matched uncertain terms with unknown bounds, is first considered. Four adaptive strategies are designed, analysed and compared to select the most effective ones to be applied to the microgrid case study. In the first two strategies, the control amplitude is continuously adjusted, so as to arrive at dominating the effect of the uncertainty on the controlled system. When a suitable control amplitude is attained, the origin of the state space of the auxiliary system becomes attractive. In the other two strategies, a suitable blend between two components, one mainly working during the reaching phase, the other being the predominant one in a vicinity of the sliding manifold, is generated, so as to reduce the control amplitude in steady state. The microgrid system in a grid-connected operation mode, controlled via the selected ASSOSM control strategies, exhibits appreciable stability properties, as proved theoretically and shown in simulation.

  2. Intelligent Engine Systems: Adaptive Control

    NASA Technical Reports Server (NTRS)

    Gibson, Nathan

    2008-01-01

    We have studied the application of the baseline Model Predictive Control (MPC) algorithm to the control of main fuel flow rate (WF36), variable bleed valve (AE24) and variable stator vane (STP25) control of a simulated high-bypass turbofan engine. Using reference trajectories for thrust and turbine inlet temperature (T41) generated by a simulated new engine, we have examined MPC for tracking these two reference outputs while controlling a deteriorated engine. We have examined the results of MPC control for six different transients: two idle-to-takeoff transients at sea level static (SLS) conditions, one takeoff-to-idle transient at SLS, a Bode power command and reverse Bode power command at 20,000 ft/Mach 0.5, and a reverse Bode transient at 35,000 ft/Mach 0.84. For all cases, our primary focus was on the computational effort required by MPC for varying MPC update rates, control horizons, and prediction horizons. We have also considered the effects of these MPC parameters on the performance of the control, with special emphasis on the thrust tracking error, the peak T41, and the sizes of violations of the constraints on the problem, primarily the booster stall margin limit, which for most cases is the lone constraint that is violated with any frequency.

  3. Adapting global influenza management strategies to address emerging viruses.

    PubMed

    Noah, Diana L; Noah, James W

    2013-07-15

    Death by respiratory complications from influenza infections continues to be a major global health concern. Antiviral drugs are widely available for therapy and prophylaxis, but viral mutations have resulted in resistance that threatens to reduce the long-term utility of approved antivirals. Vaccination is the best method for controlling influenza, but vaccine strategies are blunted by virus antigenic drift and shift. Genetic shift in particular has led to four pandemics in the last century, which have prompted the development of efficient global surveillance and vaccination programs. Although the influenza pandemic of 2009 emphasized the need for the rapid standardization of global surveillance methods and the preparation and dissemination of global assay standards for improved reporting and diagnostic tools, outbreaks of novel influenza strains continue to occur, and current efforts must be enhanced by aggressive public education programs to promote increased vaccination rates in the global population. Recently, a novel H7N9 avian influenza virus with potential to become a pandemic strain emerged in China and was transmitted from animals to humans with a demonstrated >20% mortality rate. Sporadic outbreaks of highly lethal avian virus strains have already increased public awareness and altered annual vaccine production strategies to prevent the natural adaption of this virus to human-to-human transmission. Additional strategies for combating influenza include advancement of new antivirals for unexploited viral or host cellular targets; novel adjuvants and alternate vaccine delivery systems; and development of universal protein, DNA, or multivalent vaccines designed to increase immune responsiveness and enhance public health response times.

  4. Adaptive Inner-Loop Rover Control

    NASA Technical Reports Server (NTRS)

    Kulkarni, Nilesh; Ippolito, Corey; Krishnakumar, Kalmanje; Al-Ali, Khalid M.

    2006-01-01

    Adaptive control technology is developed for the inner-loop speed and steering control of the MAX Rover. MAX, a CMU developed rover, is a compact low-cost 4-wheel drive, 4-wheel steer (double Ackerman), high-clearance agile durable chassis, outfitted with sensors and electronics that make it ideally suited for supporting research relevant to intelligent teleoperation and as a low-cost autonomous robotic test bed and appliance. The design consists of a feedback linearization based controller with a proportional - integral (PI) feedback that is augmented by an online adaptive neural network. The adaptation law has guaranteed stability properties for safe operation. The control design is retrofit in nature so that it fits inside the outer-loop path planning algorithms. Successful hardware implementation of the controller is illustrated for several scenarios consisting of actuator failures and modeling errors in the nominal design.

  5. Full Gradient Solution to Adaptive Hybrid Control

    NASA Technical Reports Server (NTRS)

    Bean, Jacob; Schiller, Noah H.; Fuller, Chris

    2016-01-01

    This paper focuses on the adaptation mechanisms in adaptive hybrid controllers. Most adaptive hybrid controllers update two filters individually according to the filtered-reference least mean squares (FxLMS) algorithm. Because this algorithm was derived for feedforward control, it does not take into account the presence of a feedback loop in the gradient calculation. This paper provides a derivation of the proper weight vector gradient for hybrid (or feedback) controllers that takes into account the presence of feedback. In this formulation, a single weight vector is updated rather than two individually. An internal model structure is assumed for the feedback part of the controller. The full gradient is equivalent to that used in the standard FxLMS algorithm with the addition of a recursive term that is a function of the modeling error. Some simulations are provided to highlight the advantages of using the full gradient in the weight vector update rather than the approximation.

  6. Full Gradient Solution to Adaptive Hybrid Control

    NASA Technical Reports Server (NTRS)

    Bean, Jacob; Schiller, Noah H.; Fuller, Chris

    2017-01-01

    This paper focuses on the adaptation mechanisms in adaptive hybrid controllers. Most adaptive hybrid controllers update two filters individually according to the filtered reference least mean squares (FxLMS) algorithm. Because this algorithm was derived for feedforward control, it does not take into account the presence of a feedback loop in the gradient calculation. This paper provides a derivation of the proper weight vector gradient for hybrid (or feedback) controllers that takes into account the presence of feedback. In this formulation, a single weight vector is updated rather than two individually. An internal model structure is assumed for the feedback part of the controller. The full gradient is equivalent to that used in the standard FxLMS algorithm with the addition of a recursive term that is a function of the modeling error. Some simulations are provided to highlight the advantages of using the full gradient in the weight vector update rather than the approximation.

  7. Adaptive isogeometric analysis based on a combined r-h strategy

    NASA Astrophysics Data System (ADS)

    Basappa, Umesh; Rajagopal, Amirtham; Reddy, J. N.

    2016-03-01

    In the present work, an r-h adaptive isogeometric analysis is proposed for plane elasticity problems. For performing the r-adaption, the control net is considered to be a network of springs with the individual spring stiffness values being proportional to the error estimated at the control points. While preserving the boundary control points, relocation of only the interior control points is made by adopting a successive relaxation approach to achieve the equilibrium of spring system. To suit the noninterpolatory nature of the isogeometric approximation, a new point-wise error estimate for the h-refinement is proposed. To evaluate the point-wise error, hierarchical B-spline functions in Sobolev spaces are considered. The proposed adaptive h-refinement strategy is based on using De-Casteljau's algorithm for obtaining the new control points. The subsequent control meshes are thus obtained by using a recursive subdivision of reference control mesh. Such a strategy ensures that the control points lie in the physical domain in subsequent refinements, thus making the physical mesh to exactly interpolate the control mesh and thereby allowing the exact imposition of essential boundary conditions in the classical isogeometric analysis (IGA). The combined r-h adaptive refinement strategy results in better convergence characteristics with reduced errors than r- or h-refinement. Several numerical examples are presented to illustrate the efficiency of the proposed approach.

  8. Machining Strategy to Adapt Cutting Conditions under Digital Copy Milling Concept

    NASA Astrophysics Data System (ADS)

    Shimada, Takashi; Nakamoto, Keiichi; Shirase, Keiichi

    Most machining tools are controlled by numerical control (NC) programs in order to achieve unmanned machining operations with high precision and improved productivity. However, all the movements of the machining tool are predetermined, and all instructions coded in the NC program are performed sequentially. Therefore, since the cutting process is not adaptable during unmanned machining, the cutting conditions should be set conservatively to avoid cutting difficulties. In this study, machining strategies for adapting the cutting process during a milling operation to avoid tool breakage and to stabilize cutting load have been integrated into an autonomous NC machining tool developed under the Digital Copy Milling (DCM) concept for generating a tool path in real time. In machining strategies, feed speed, radial and axial depths of cut are adapted according to cutting load detected from load cells in the machining table. Successful endmilling experiments verified the effectiveness of the developed machining strategy.

  9. Adapting Strategies of Effective Instruction for Culturally Diverse Preschoolers

    ERIC Educational Resources Information Center

    Yamauchi, Lois A.; Im, Seongah; Schonleber, Nanette S.

    2012-01-01

    This article describes collaboration between preschool and university educators focused on adapting the Center for Research on Education, Diversity, and Excellence (CREDE) standards for Effective Pedagogy for use in early childhood (EC) settings. The CREDE standards are strategies of best practices for culturally diverse K-12 students. Teachers…

  10. Direct adaptive impedance control of manipulators

    NASA Technical Reports Server (NTRS)

    Colbaugh, R.; Seraji, H.; Glass, K.

    1991-01-01

    An adaptive scheme for controlling the end-effector impedance of robot manipulators is presented. The proposed control system consists of three subsystems: a simple filter which characterizes the desired dynamic relationship between the end-effector position error and the end-effector/environment contact force, an adaptive controller which produces the Cartesian-space control input required to provide this desired dynamic relationship, and an algorithm for mapping the Cartesian-space control input to a physically realizable joint-space control torque. The controller does not require knowledge of either the structure or the parameter values of the robot dynamics, and it is implemented without calculation of the robot inverse kinematic transformation. As a result, the scheme represents a very general and computationally efficient approach to controlling the impedance of both nonredundant and redundant manipulators. Furthermore, the method can be applied directly to trajectory tracking in free-space motion by removing the impedance filter.

  11. Maritime Adaptive Optics Beam Control

    DTIC Science & Technology

    2010-09-01

    mantis shrimp for getting me through the home stretch. To all my advisors, mentors, friends, and family—you have my eternal gratitude for helping...the RLS algorithm does in fact converge faster than the LMS algorithm, yet at the same time the LMS algorithm can control significantly better during

  12. Adaptive mesh refinement strategies in isogeometric analysis— A computational comparison

    NASA Astrophysics Data System (ADS)

    Hennig, Paul; Kästner, Markus; Morgenstern, Philipp; Peterseim, Daniel

    2017-04-01

    We explain four variants of an adaptive finite element method with cubic splines and compare their performance in simple elliptic model problems. The methods in comparison are Truncated Hierarchical B-splines with two different refinement strategies, T-splines with the refinement strategy introduced by Scott et al. in 2012, and T-splines with an alternative refinement strategy introduced by some of the authors. In four examples, including singular and non-singular problems of linear elasticity and the Poisson problem, the H1-errors of the discrete solutions, the number of degrees of freedom as well as sparsity patterns and condition numbers of the discretized problem are compared.

  13. Language control in bilinguals: The adaptive control hypothesis.

    PubMed

    Green, David W; Abutalebi, Jubin

    2013-08-01

    Speech comprehension and production are governed by control processes. We explore their nature and dynamics in bilingual speakers with a focus on speech production. Prior research indicates that individuals increase cognitive control in order to achieve a desired goal. In the adaptive control hypothesis we propose a stronger hypothesis: Language control processes themselves adapt to the recurrent demands placed on them by the interactional context. Adapting a control process means changing a parameter or parameters about the way it works (its neural capacity or efficiency) or the way it works in concert, or in cascade, with other control processes (e.g., its connectedness). We distinguish eight control processes (goal maintenance, conflict monitoring, interference suppression, salient cue detection, selective response inhibition, task disengagement, task engagement, opportunistic planning). We consider the demands on these processes imposed by three interactional contexts (single language, dual language, and dense code-switching). We predict adaptive changes in the neural regions and circuits associated with specific control processes. A dual-language context, for example, is predicted to lead to the adaptation of a circuit mediating a cascade of control processes that circumvents a control dilemma. Effective test of the adaptive control hypothesis requires behavioural and neuroimaging work that assesses language control in a range of tasks within the same individual.

  14. Language control in bilinguals: The adaptive control hypothesis

    PubMed Central

    Abutalebi, Jubin

    2013-01-01

    Speech comprehension and production are governed by control processes. We explore their nature and dynamics in bilingual speakers with a focus on speech production. Prior research indicates that individuals increase cognitive control in order to achieve a desired goal. In the adaptive control hypothesis we propose a stronger hypothesis: Language control processes themselves adapt to the recurrent demands placed on them by the interactional context. Adapting a control process means changing a parameter or parameters about the way it works (its neural capacity or efficiency) or the way it works in concert, or in cascade, with other control processes (e.g., its connectedness). We distinguish eight control processes (goal maintenance, conflict monitoring, interference suppression, salient cue detection, selective response inhibition, task disengagement, task engagement, opportunistic planning). We consider the demands on these processes imposed by three interactional contexts (single language, dual language, and dense code-switching). We predict adaptive changes in the neural regions and circuits associated with specific control processes. A dual-language context, for example, is predicted to lead to the adaptation of a circuit mediating a cascade of control processes that circumvents a control dilemma. Effective test of the adaptive control hypothesis requires behavioural and neuroimaging work that assesses language control in a range of tasks within the same individual. PMID:25077013

  15. An adaptive pattern based nonlinear PID controller.

    PubMed

    Segovia, Juan Pablo; Sbarbaro, Daniel; Ceballos, Eric

    2004-04-01

    This paper presents a nonlinear proportional-integral-derivative (PID) controller, combining a pattern based adaptive algorithm to cope with the problem of tuning the controller, and an associative memory to store the parameters, according to different operating conditions. The simplicity of the algorithm enables its implementation in current programmable logic controller technology. Several real-time experiments, carried out in a pressurized tank, illustrate the performance of the proposed controller.

  16. Adaptive Modal Identification for Flutter Suppression Control

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan T.; Drew, Michael; Swei, Sean S.

    2016-01-01

    In this paper, we will develop an adaptive modal identification method for identifying the frequencies and damping of a flutter mode based on model-reference adaptive control (MRAC) and least-squares methods. The least-squares parameter estimation will achieve parameter convergence in the presence of persistent excitation whereas the MRAC parameter estimation does not guarantee parameter convergence. Two adaptive flutter suppression control approaches are developed: one based on MRAC and the other based on the least-squares method. The MRAC flutter suppression control is designed as an integral part of the parameter estimation where the feedback signal is used to estimate the modal information. On the other hand, the separation principle of control and estimation is applied to the least-squares method. The least-squares modal identification is used to perform parameter estimation.

  17. Adaptive Control Of Large Vibrating, Rotating Structures

    NASA Technical Reports Server (NTRS)

    Bayard, David S.

    1991-01-01

    Globally convergent theoretical method provides for adaptive set-point control of orientation of, along with suppression of the vibrations of, large structure. Method utilizes inherent passivity properties of structure to attain mathematical condition essential to adaptive convergence on commanded set point. Maintains stability and convergence in presence of errors in mathematical model of dynamics of structure and actuators. Developed for controlling attitudes of large, somewhat flexible spacecraft, also useful in such terrestrial applications as controlling movable bridges or suppressing earthquake vibrations in bridges, buildings, and other large structures.

  18. Dual adaptive control: Design principles and applications

    NASA Technical Reports Server (NTRS)

    Mookerjee, Purusottam

    1988-01-01

    The design of an actively adaptive dual controller based on an approximation of the stochastic dynamic programming equation for a multi-step horizon is presented. A dual controller that can enhance identification of the system while controlling it at the same time is derived for multi-dimensional problems. This dual controller uses sensitivity functions of the expected future cost with respect to the parameter uncertainties. A passively adaptive cautious controller and the actively adaptive dual controller are examined. In many instances, the cautious controller is seen to turn off while the latter avoids the turn-off of the control and the slow convergence of the parameter estimates, characteristic of the cautious controller. The algorithms have been applied to a multi-variable static model which represents a simplified linear version of the relationship between the vibration output and the higher harmonic control input for a helicopter. Monte Carlo comparisons based on parametric and nonparametric statistical analysis indicate the superiority of the dual controller over the baseline controller.

  19. Adaptive Process Control in Rubber Industry.

    PubMed

    Brause, Rüdiger W; Pietruschka, Ulf

    1998-01-01

    This paper describes the problems and an adaptive solution for process control in rubber industry. We show that the human and economical benefits of an adaptive solution for the approximation of process parameters are very attractive. The modeling of the industrial problem is done by the means of artificial neural networks. For the example of the extrusion of a rubber profile in tire production our method shows good resuits even using only a few training samples.

  20. Advanced traffic control strategies for intelligent vehicle highway systems

    NASA Astrophysics Data System (ADS)

    Gartner, Nathan H.; Stamatiadis, C.; Tarnoff, P. J.

    1995-01-01

    This paper discusses traffic signal control strategies that are suitable for advanced traffic management within IVHS (Intelligent Vehicle Highway Systems). The strategies consist of a multi-level design for the real-time, traffic-adaptive control of the urban signal network system. Each control level has different response characteristics, with the more advanced levels incorporating in a nested fashion the capabilities of the lower levels. A principal goal of the new multi-level design is to invoke a selected control strategy when it can provide the greatest benefit.

  1. Exposure to Stressful Environments: Strategy of Adaptive Responses

    NASA Technical Reports Server (NTRS)

    Farhi, Leon E.

    1991-01-01

    Any new natural environment may generate a number of stresses (such as hypoxia, water lack, and heat exposure), each of which can produce strains in more than a single organ system. Every strain may in turn stimulate the body to adapt in multiple ways. Nevertheless, a general strategy of the various adaptive responses emerges when the challenges are divided into three groups. The first category includes conditions that affect the supply of essential molecules, while the second is made up by those stresses that prevent the body from regulating properly the output of waste products, such as CO2 and heat. In both classes, there is a small number of responses, similar in principle, regardless of the specific situation. The third unit is created by environments that disrupt body transport systems. Problems may arise when there is a conflict between two stresses requiring conflicting adaptive changes. An alternative to adaptation, creation of micro-environment, is often favored by the animal.

  2. 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

  3. Adaptive Neural Network Controller for ATM Traffic

    DTIC Science & Technology

    1996-12-01

    IEEE Communications Magazine (October 1995). 2. Baum, Eric B...Adaptive Control in ATM Networks," IEEE Communications Magazine (October 1995). 9. Evanowsky, John B. "Information for the Warrior," IEEE Communications Magazine (October...Network Applications in ATM," IEEE Communications Magazine (October 1995). 78 16. Imrich, et al. "A counter based congestion control for ATM

  4. Multiprocessor Adaptive Control Of A Dynamic System

    NASA Technical Reports Server (NTRS)

    Juang, Jer-Nan; Hyland, David C.

    1995-01-01

    Architecture for fully autonomous digital electronic control system developed for use in identification and adaptive control of dynamic system. Architecture modular and hierarchical. Combines relatively simple, standardized processing units into complex parallel-processing subsystems. Although architecture based on neural-network concept, processing units themselves not neural networks; processing units implemented by programming of currently available microprocessors.

  5. The importance of training strategy adaptation: a learner-oriented approach for improving older adults' memory and transfer.

    PubMed

    Bottiroli, Sara; Cavallini, Elena; Dunlosky, John; Vecchi, Tomaso; Hertzog, Christopher

    2013-09-01

    We investigated the benefits of strategy-adaptation training for promoting transfer effects. This learner-oriented approach--which directly encourages the learner to generalize strategic behavior to new tasks--helps older adults appraise new tasks and adapt trained strategies to them. In Experiment 1, older adults in a strategy-adaptation training group used 2 strategies (imagery and sentence generation) while practicing 2 tasks (list and associative learning); they were then instructed on how to do a simple task analysis to help them adapt the trained strategies for 2 different unpracticed tasks (place learning and text learning) that were discussed during training. Two additional criterion tasks (name-face associative learning and grocery-list learning) were never mentioned during training. Two other groups were included: A strategy training group (who received strategy training and transfer instructions but not strategy-adaptation training) and a waiting-list control group. Both training procedures enhanced older adults' performance on the trained tasks and those tasks that were discussed during training, but transfer was greatest after strategy-adaptation training. Experiment 2 found that strategy-adaptation training conducted via a manual that older adults used at home also promoted transfer. These findings demonstrate the importance of adopting a learner-oriented approach to promote transfer of strategy training.

  6. Adaptive control design for hysteretic smart systems

    NASA Astrophysics Data System (ADS)

    Fan, Xiang; Smith, Ralph C.

    2009-03-01

    Ferroelectric and ferromagnetic actuators are being considered for a range of industrial, aerospace, aeronautic and biomedical applications due to their unique transduction capabilities. However, they also exhibit hysteretic and nonlinear behavior that must be accommodated in models and control designs. If uncompensated, these effects can yield reduced system performance and, in the worst case, can produce unpredictable behavior of the control system. One technique for control design is to approximately linearize the actuator dynamics using an adaptive inverse compensator that is also able to accommodate model uncertainties and error introduced by the inverse algorithm. This paper describes the design of an adaptive inverse control technique based on the homogenized energy model for hysteresis. The resulting inverse filter is incorporated in an L1 control theory to provide a robust control algorithm capable of providing high speed, high accuracy tracking in the presence of actuator hysteresis and nonlinearities. Properties of the control design are illustrated through numerical examples.

  7. Assessment of the effectiveness of flood adaptation strategies for HCMC

    NASA Astrophysics Data System (ADS)

    Lasage, R.; Veldkamp, T. I. E.; de Moel, H.; Van, T. C.; Phi, H. L.; Vellinga, P.; Aerts, J. C. J. H.

    2014-06-01

    Coastal cities are vulnerable to flooding, and flood risk to coastal cities will increase due to sea-level rise. Moreover, Asian cities in particular are subject to considerable population growth and associated urban developments, increasing this risk even more. Empirical data on vulnerability and the cost and benefits of flood risk reduction measures are therefore paramount for sustainable development of these cities. This paper presents an approach to explore the impacts of sea-level rise and socio-economic developments on flood risk for the flood-prone District 4 in Ho Chi Minh City, Vietnam, and to develop and evaluate the effects of different adaptation strategies (new levees, dry- and wet proofing of buildings and elevating roads and buildings). A flood damage model was developed to simulate current and future flood risk using the results from a household survey to establish stage-damage curves for residential buildings. The model has been used to assess the effects of several participatory developed adaptation strategies to reduce flood risk, expressed in expected annual damage (EAD). Adaptation strategies were evaluated assuming combinations of both sea-level scenarios and land-use scenarios. Together with information on costs of these strategies, we calculated the benefit-cost ratio and net present value for the adaptation strategies until 2100, taking into account depreciation rates of 2.5% and 5%. The results of this modelling study indicate that the current flood risk in District 4 is USD 0.31 million per year, increasing up to USD 0.78 million per year in 2100. The net present value and benefit-cost ratios using a discount rate of 5 % range from USD -107 to -1.5 million, and from 0.086 to 0.796 for the different strategies. Using a discount rate of 2.5% leads to an increase in both net present value and benefit-cost ratio. The adaptation strategies wet-proofing and dry-proofing generate the best results using these economic indicators. The information

  8. Adaptive neural control of aeroelastic response

    NASA Astrophysics Data System (ADS)

    Lichtenwalner, Peter F.; Little, Gerald R.; Scott, Robert C.

    1996-05-01

    The Adaptive Neural Control of Aeroelastic Response (ANCAR) program is a joint research and development effort conducted by McDonnell Douglas Aerospace (MDA) and the National Aeronautics and Space Administration, Langley Research Center (NASA LaRC) under a Memorandum of Agreement (MOA). The purpose of the MOA is to cooperatively develop the smart structure technologies necessary for alleviating undesirable vibration and aeroelastic response associated with highly flexible structures. Adaptive control can reduce aeroelastic response associated with buffet and atmospheric turbulence, it can increase flutter margins, and it may be able to reduce response associated with nonlinear phenomenon like limit cycle oscillations. By reducing vibration levels and loads, aircraft structures can have lower acquisition cost, reduced maintenance, and extended lifetimes. Phase I of the ANCAR program involved development and demonstration of a neural network-based semi-adaptive flutter suppression system which used a neural network for scheduling control laws as a function of Mach number and dynamic pressure. This controller was tested along with a robust fixed-gain control law in NASA's Transonic Dynamics Tunnel (TDT) utilizing the Benchmark Active Controls Testing (BACT) wing. During Phase II, a fully adaptive on-line learning neural network control system has been developed for flutter suppression which will be tested in 1996. This paper presents the results of Phase I testing as well as the development progress of Phase II.

  9. Adaptive impedance control of a robotic orthosis for gait rehabilitation.

    PubMed

    Hussain, Shahid; Xie, Sheng Q; Jamwal, Prashant K

    2013-06-01

    Intervention of robotic devices in the field of physical gait therapy can help in providing repetitive, systematic, and economically viable training sessions. Interactive or assist-as-needed (AAN) gait training encourages patient voluntary participation in the robotic gait training process which may aid in rapid motor function recovery. In this paper, a lightweight robotic gait training orthosis with two actuated and four passive degrees of freedom (DOFs) is proposed. The actuated DOFs were powered by pneumatic muscle actuators. An AAN gait training paradigm based on adaptive impedance control was developed to provide interactive robotic gait training. The proposed adaptive impedance control scheme adapts the robotic assistance according to the disability level and voluntary participation of human subjects. The robotic orthosis was operated in two gait training modes, namely, inactive mode and active mode, to evaluate the performance of the proposed control scheme. The adaptive impedance control scheme was evaluated on ten neurologically intact subjects. The experimental results demonstrate that an increase in voluntary participation of human subjects resulted in a decrease of the robotic assistance and vice versa. Further clinical evaluations with neurologically impaired subjects are required to establish the therapeutic efficacy of the adaptive-impedance-control-based AAN gait training strategy.

  10. 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

  11. 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.

  12. Adaptive control of an unmanned aerial vehicle

    NASA Astrophysics Data System (ADS)

    Nguen, V. F.; Putov, A. V.; Nguen, T. T.

    2017-01-01

    The paper deals with design and comparison of adaptive control systems based on plant state vector and output for unmanned aerial vehicle (UAV) with nonlinearity and uncertainty of parameters of the aircraft incomplete measurability of its state and presence of wind disturbances. The results of computer simulations of flight stabilization processes on the example of the experimental model UAV-70V (Aerospace Academy, Hanoi) with presence of periodic and non-periodic vertical wind disturbances with designed adaptive control systems based on plant state vector with state observer and plant output.

  13. Hardware verification of distributed/adaptive control

    NASA Technical Reports Server (NTRS)

    Eldred, D. B.; Schaechter, D. B.

    1983-01-01

    Adaptive control techniques are studied for their future application to the control of large space structures, where uncertain or changing parameters may destabilize standard control system designs. The approach used is to examine an extended Kalman filter estimator, in which the state vector is augmented with the unknown parameters. The associated Riccatti equation is linearized about the case of exact knowledge of the parameters. By assuming that parameter variations occur slowly, the filter complexity is reduced further yet. Simulations on a two degree-of-freedom oscillator demonstrate the parameter-tracking capability of the filter, and an implementation on the JPL Flexible Beam Facility using an incorrect model shows the adaptive filter/optimal control to be stable where a standard Kalman filter/optimal control design is unstable.

  14. Evolving Systems and Adaptive Key Component Control

    NASA Technical Reports Server (NTRS)

    Frost, Susan A.; Balas, Mark J.

    2009-01-01

    We propose a new framework called Evolving Systems to describe the self-assembly, or autonomous assembly, of actively controlled dynamical subsystems into an Evolved System with a higher purpose. An introduction to Evolving Systems and exploration of the essential topics of the control and stability properties of Evolving Systems is provided. This chapter defines a framework for Evolving Systems, develops theory and control solutions for fundamental characteristics of Evolving Systems, and provides illustrative examples of Evolving Systems and their control with adaptive key component controllers.

  15. Bounded Linear Stability Margin Analysis of Nonlinear Hybrid Adaptive Control

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan T.; Boskovic, Jovan D.

    2008-01-01

    This paper presents a bounded linear stability analysis for a hybrid adaptive control that blends both direct and indirect adaptive control. Stability and convergence of nonlinear adaptive control are analyzed using an approximate linear equivalent system. A stability margin analysis shows that a large adaptive gain can lead to a reduced phase margin. This method can enable metrics-driven adaptive control whereby the adaptive gain is adjusted to meet stability margin requirements.

  16. Transitions in optimal adaptive strategies for populations in fluctuating environments

    NASA Astrophysics Data System (ADS)

    Mayer, Andreas; Mora, Thierry; Rivoire, Olivier; Walczak, Aleksandra M.

    2017-09-01

    Biological populations are subject to fluctuating environmental conditions. Different adaptive strategies can allow them to cope with these fluctuations: specialization to one particular environmental condition, adoption of a generalist phenotype that compromises between conditions, or population-wise diversification (bet hedging). Which strategy provides the largest selective advantage in the long run depends on the range of accessible phenotypes and the statistics of the environmental fluctuations. Here, we analyze this problem in a simple mathematical model of population growth. First, we review and extend a graphical method to identify the nature of the optimal strategy when the environmental fluctuations are uncorrelated. Temporal correlations in environmental fluctuations open up new strategies that rely on memory but are mathematically challenging to study: We present analytical results to address this challenge. We illustrate our general approach by analyzing optimal adaptive strategies in the presence of trade-offs that constrain the range of accessible phenotypes. Our results extend several previous studies and have applications to a variety of biological phenomena, from antibiotic resistance in bacteria to immune responses in vertebrates.

  17. Adaptive mechanism-based congestion control for networked systems

    NASA Astrophysics Data System (ADS)

    Liu, Zhi; Zhang, Yun; Chen, C. L. Philip

    2013-03-01

    In order to assure the communication quality in network systems with heavy traffic and limited bandwidth, a new ATRED (adaptive thresholds random early detection) congestion control algorithm is proposed for the congestion avoidance and resource management of network systems. Different to the traditional AQM (active queue management) algorithms, the control parameters of ATRED are not configured statically, but dynamically adjusted by the adaptive mechanism. By integrating with the adaptive strategy, ATRED alleviates the tuning difficulty of RED (random early detection) and shows a better control on the queue management, and achieve a more robust performance than RED under varying network conditions. Furthermore, a dynamic transmission control protocol-AQM control system using ATRED controller is introduced for the systematic analysis. It is proved that the stability of the network system can be guaranteed when the adaptive mechanism is finely designed. Simulation studies show the proposed ATRED algorithm achieves a good performance in varying network environments, which is superior to the RED and Gentle-RED algorithm, and providing more reliable service under varying network conditions.

  18. Diversity of immune strategies explained by adaptation to pathogen statistics

    PubMed Central

    Mayer, Andreas; Mora, Thierry; Rivoire, Olivier; Walczak, Aleksandra M.

    2016-01-01

    Biological organisms have evolved a wide range of immune mechanisms to defend themselves against pathogens. Beyond molecular details, these mechanisms differ in how protection is acquired, processed, and passed on to subsequent generations—differences that may be essential to long-term survival. Here, we introduce a mathematical framework to compare the long-term adaptation of populations as a function of the pathogen dynamics that they experience and of the immune strategy that they adopt. We find that the two key determinants of an optimal immune strategy are the frequency and the characteristic timescale of the pathogens. Depending on these two parameters, our framework identifies distinct modes of immunity, including adaptive, innate, bet-hedging, and CRISPR-like immunities, which recapitulate the diversity of natural immune systems. PMID:27432970

  19. Diversity of immune strategies explained by adaptation to pathogen statistics.

    PubMed

    Mayer, Andreas; Mora, Thierry; Rivoire, Olivier; Walczak, Aleksandra M

    2016-08-02

    Biological organisms have evolved a wide range of immune mechanisms to defend themselves against pathogens. Beyond molecular details, these mechanisms differ in how protection is acquired, processed, and passed on to subsequent generations-differences that may be essential to long-term survival. Here, we introduce a mathematical framework to compare the long-term adaptation of populations as a function of the pathogen dynamics that they experience and of the immune strategy that they adopt. We find that the two key determinants of an optimal immune strategy are the frequency and the characteristic timescale of the pathogens. Depending on these two parameters, our framework identifies distinct modes of immunity, including adaptive, innate, bet-hedging, and CRISPR-like immunities, which recapitulate the diversity of natural immune systems.

  20. 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.

  1. Ensemble analysis of adaptive compressed genome sequencing strategies.

    PubMed

    Taghavi, Zeinab

    2014-01-01

    Acquiring genomes at single-cell resolution has many applications such as in the study of microbiota. However, deep sequencing and assembly of all of millions of cells in a sample is prohibitively costly. A property that can come to rescue is that deep sequencing of every cell should not be necessary to capture all distinct genomes, as the majority of cells are biological replicates. Biologically important samples are often sparse in that sense. In this paper, we propose an adaptive compressed method, also known as distilled sensing, to capture all distinct genomes in a sparse microbial community with reduced sequencing effort. As opposed to group testing in which the number of distinct events is often constant and sparsity is equivalent to rarity of an event, sparsity in our case means scarcity of distinct events in comparison to the data size. Previously, we introduced the problem and proposed a distilled sensing solution based on the breadth first search strategy. We simulated the whole process which constrained our ability to study the behavior of the algorithm for the entire ensemble due to its computational intensity. In this paper, we modify our previous breadth first search strategy and introduce the depth first search strategy. Instead of simulating the entire process, which is intractable for a large number of experiments, we provide a dynamic programming algorithm to analyze the behavior of the method for the entire ensemble. The ensemble analysis algorithm recursively calculates the probability of capturing every distinct genome and also the expected total sequenced nucleotides for a given population profile. Our results suggest that the expected total sequenced nucleotides grows proportional to log of the number of cells and proportional linearly with the number of distinct genomes. The probability of missing a genome depends on its abundance and the ratio of its size over the maximum genome size in the sample. The modified resource allocation method

  2. Adaptive self-correcting control system

    SciTech Connect

    Ellis, S.H.

    1984-01-03

    A control system for regulating a controlled device or process, such as a turbofan engine, produces independent multiple estimates of one or more controlled variables of the device or process by combining the signals from a plurality of feedback sensors, which provide information related to the controlled variables, in weighted nonordered pairs. The independent multiple estimates of each controlled variable are combined into a weighted average, and individual estimates which differ by more than a specified amount from the weighted average are edited and temporarily removed from consideration. A revised weighted average value of each controlled variable is then produced, and this value is used to limit or control operation of the device or process. Adaptive trim is provided to compensate for changes in the device or process being controlled, such as engine deterioration, by slowly trimming each individual estimate toward the mean, and includes error compensation which constrains the weighted sum of the adaptive trims to equal zero, thereby preventing the adaptive trim from changing the operating level of the device or process. A secondary editing circuit based on a majority rule principle identifies a failed feedback sensor and permanently excludes all individual estimates of the controlled variable based on the failed sensor. Editing boundaries are increased and adaptive trim rate is varied when a transient occurs in the operation of the device or process. Further transient compensation may be required for a system with more severe transient requirements, and this invention includes compensation to selected feedback parameters such as turbine temperature to account for differences between steady state and transient values.

  3. Malaria control strategies in French armed forces.

    PubMed

    Migliani, R; Pradines, B; Michel, R; Aoun, O; Dia, A; Deparis, X; Rapp, C

    2014-01-01

    Each year, 40,000 French soldiers deploy or travel through malaria-endemic areas. Despite the effective control measures that were successively implemented, malaria remains a public health concern in French armed forces with several important outbreaks and one lethal case every two years. This article describes the malaria control strategy in French armed forces which is based on three combined strategies: i) Anopheles vector control to prevent infection with the implementation of personal protection against vectors (PPAV) adapted to the field living conditions of the troops. ii) Chemoprophylaxis (CP) to prevent the disease based on prescription of effective and well tolerated doxycycline. iii) Management of cases through early diagnosis and appropriate treatment to prevent death. In isolated conditions in endemic areas, rapid diagnosis tests (RDT) are used as first-line tests by military doctors. Treatment of uncomplicated Plasmodium falciparum (P. falciparum) malaria is based either on the piperaquine tetraphosphate-dihydroartemisinin association since 2013, or on the atovaquone-proguanil association. First-line treatment of severe P. falciparum malaria is based on IV artesunate. These measures are associated with constant education of the military, epidemiological surveillance of malaria cases and monitoring of parasite chemosensitivity.

  4. Adaptive Control of Nonlinear and Stochastic Systems

    DTIC Science & Technology

    1991-01-14

    Hernmndez-Lerma and S.I. Marcus, Nonparametric adaptive control of dis- crete time partially observable stochastic systems, Journal of Mathematical Analysis and Applications 137... Journal of Mathematical Analysis and Applications 137 (1989), 485-514. [19] A. Arapostathis and S.I. Marcus, Analysis of an identification algorithm

  5. Adaptive control system for gas producing wells

    SciTech Connect

    Fedor, Pashchenko; Sergey, Gulyaev; Alexander, Pashchenko

    2015-03-10

    Optimal adaptive automatic control system for gas producing wells cluster is proposed intended for solving the problem of stabilization of the output gas pressure in the cluster at conditions of changing gas flow rate and changing parameters of the wells themselves, providing the maximum high resource of hardware elements of automation.

  6. Predictive Control of Speededness in Adaptive Testing

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    2009-01-01

    An adaptive testing method is presented that controls the speededness of a test using predictions of the test takers' response times on the candidate items in the pool. Two different types of predictions are investigated: posterior predictions given the actual response times on the items already administered and posterior predictions that use the…

  7. Predictive Control of Speededness in Adaptive Testing

    ERIC Educational Resources Information Center

    van der Linden, Wim J.

    2009-01-01

    An adaptive testing method is presented that controls the speededness of a test using predictions of the test takers' response times on the candidate items in the pool. Two different types of predictions are investigated: posterior predictions given the actual response times on the items already administered and posterior predictions that use the…

  8. Forward Stochastic Nonlinear Adaptive Control Method

    NASA Technical Reports Server (NTRS)

    Bayard, David S.

    1990-01-01

    New method of computation for optimal stochastic nonlinear and adaptive control undergoing development. Solves systematically stochastic dynamic programming equations forward in time, using nested-stochastic-approximation technique. Main advantage, simplicity of programming and reduced complexity with clear performance/computation trade-offs.

  9. Climate change impacts and adaptive strategies: lessons from the grapevine.

    PubMed

    Mosedale, Jonathan R; Abernethy, Kirsten E; Smart, Richard E; Wilson, Robert J; Maclean, Ilya M D

    2016-11-01

    The cultivation of grapevines for winemaking, known as viticulture, is widely cited as a climate-sensitive agricultural system that has been used as an indicator of both historic and contemporary climate change. Numerous studies have questioned the viability of major viticulture regions under future climate projections. We review the methods used to study the impacts of climate change on viticulture in the light of what is known about the effects of climate and weather on the yields and quality of vineyard harvests. Many potential impacts of climate change on viticulture, particularly those associated with a change in climate variability or seasonal weather patterns, are rarely captured. Key biophysical characteristics of viticulture are often unaccounted for, including the variability of grapevine phenology and the exploitation of microclimatic niches that permit successful cultivation under suboptimal macroclimatic conditions. We consider how these same biophysical characteristics permit a variety of strategies by which viticulture can adapt to changing climatic conditions. The ability to realize these strategies, however, is affected by uneven exposure to risks across the winemaking sector, and the evolving capacity for decision-making within and across organizational boundaries. The role grape provenance plays in shaping perceptions of wine value and quality illustrates how conflicts of interest influence decisions about adaptive strategies within the industry. We conclude by considering what lessons can be taken from viticulture for studies of climate change impacts and the capacity for adaptation in other agricultural and natural systems.

  10. Adaptive strategies to climate change in Southern Malawi

    NASA Astrophysics Data System (ADS)

    Chidanti-Malunga, J.

    Climate change poses a big challenge to rural livelihoods in the Shire Valley area of Southern Malawi, where communities have depended almost entirely on rain-fed agriculture for generations. The Shire Valley area comprises of low-altitude dambo areas and uplands which have been the main agricultural areas. Since early to mid 1980s, the uplands have experienced prolonged droughts and poor rainfall distribution, while the dambos have experienced recurrent seasonal floods. This study assessed some of the adaptive strategies exercised by small-scale rural farmers in response to climate change in the Shire Valley. The methodology used in collecting information includes group discussions, household surveys in the area, secondary data, and field observations. The results show that small-scale rural farmers exercise a number of adaptive strategies in response to climate change. These adaptive strategies include: increased use of water resources for small-scale irrigation or wetland farming, mostly using simple delivery techniques; increased management of residual moisture; and increased alternative sources of income such as fishing and crop diversity. It was also observed that government promoted the use of portable motorized pumps for small-scale irrigation in order to mitigate the effects of climate change. However, these external interventions were not fully adopted; instead the farmers preferred local interventions which mostly had indigenous elements.

  11. Strategies to adapt to an uncertain climate change

    NASA Astrophysics Data System (ADS)

    Hallegatte, S.

    2008-05-01

    Many decisions concerning long-lived investments need to take into account climate change. But doing so is not easy for at least two reasons. First, due to the rate of climate change, new infrastructure will have to be able to cope with a large range of changing climate conditions, which will make design more difficult and construction more expensive. Second, uncertainty in future climate makes it impossible to directly use the output of a single climate model as an input for infrastructure design, and there are good reasons to think that the needed climate information will not be available soon. Instead of optimizing based on the climate conditions projected by models, therefore, future infrastructure should be made more robust to possible changes in climate conditions. This aim implies that users of climate information must also change their practices and decision-making frameworks, for instance by adapting the uncertainty-management methods they currently apply to exchange rates or R&D outcomes. Five methods are examined: (i) introducing long-term prospective exercises; (ii) selecting "no-regret" strategies; (iii) favouring reversible options; (iv) promoting soft adaptation strategies; (v) reducing decision time horizons. I argue that adaptation strategies should not be assessed in an isolated context. In particular, it is essential to consider both negative and positive side-effects and externalities, and possible changes in future energy costs.

  12. Adaptive Control of Nonlinear Flexible Systems

    DTIC Science & Technology

    1993-01-18

    disturbances. The following example illustrates the need for a robust state-feedback law and the sensi- tivity of the exact - linearization based control law... exact linearization , one can bring an input-output approach to a particular case of certainty- equivalence based adaptive control design. We now...are available for this model, exact linearization can be performed. Let C(s) be the compensator that is being used so far in the previous three

  13. 40 CFR 52.07 - Control strategies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Control strategies. 52.07 Section 52.07... PROMULGATION OF IMPLEMENTATION PLANS General Provisions § 52.07 Control strategies. (a) Each subpart specifies in what respects the control strategies are approved or disapproved. Where emission limitations...

  14. 40 CFR 52.07 - Control strategies.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 3 2013-07-01 2013-07-01 false Control strategies. 52.07 Section 52.07... PROMULGATION OF IMPLEMENTATION PLANS General Provisions § 52.07 Control strategies. (a) Each subpart specifies in what respects the control strategies are approved or disapproved. Where emission limitations with...

  15. 40 CFR 52.07 - Control strategies.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 3 2014-07-01 2014-07-01 false Control strategies. 52.07 Section 52.07... PROMULGATION OF IMPLEMENTATION PLANS General Provisions § 52.07 Control strategies. (a) Each subpart specifies in what respects the control strategies are approved or disapproved. Where emission limitations with...

  16. 40 CFR 52.07 - Control strategies.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 3 2011-07-01 2011-07-01 false Control strategies. 52.07 Section 52.07... PROMULGATION OF IMPLEMENTATION PLANS General Provisions § 52.07 Control strategies. (a) Each subpart specifies in what respects the control strategies are approved or disapproved. Where emission limitations with...

  17. 40 CFR 52.07 - Control strategies.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 3 2012-07-01 2012-07-01 false Control strategies. 52.07 Section 52.07... PROMULGATION OF IMPLEMENTATION PLANS General Provisions § 52.07 Control strategies. (a) Each subpart specifies in what respects the control strategies are approved or disapproved. Where emission limitations with...

  18. Adaptive Variable Bias Magnetic Bearing Control

    NASA Technical Reports Server (NTRS)

    Johnson, Dexter; Brown, Gerald V.; Inman, Daniel J.

    1998-01-01

    Most magnetic bearing control schemes use a bias current with a superimposed control current to linearize the relationship between the control current and the force it delivers. With the existence of the bias current, even in no load conditions, there is always some power consumption. In aerospace applications, power consumption becomes an important concern. In response to this concern, an alternative magnetic bearing control method, called Adaptive Variable Bias Control (AVBC), has been developed and its performance examined. The AVBC operates primarily as a proportional-derivative controller with a relatively slow, bias current dependent, time-varying gain. The AVBC is shown to reduce electrical power loss, be nominally stable, and provide control performance similar to conventional bias control. Analytical, computer simulation, and experimental results are presented in this paper.

  19. Adaptive fuzzy-neural-network control for maglev transportation system.

    PubMed

    Wai, Rong-Jong; Lee, Jeng-Dao

    2008-01-01

    A magnetic-levitation (maglev) transportation system including levitation and propulsion control is a subject of considerable scientific interest because of highly nonlinear and unstable behaviors. In this paper, the dynamic model of a maglev transportation system including levitated electromagnets and a propulsive linear induction motor (LIM) based on the concepts of mechanical geometry and motion dynamics is developed first. Then, a model-based sliding-mode control (SMC) strategy is introduced. In order to alleviate chattering phenomena caused by the inappropriate selection of uncertainty bound, a simple bound estimation algorithm is embedded in the SMC strategy to form an adaptive sliding-mode control (ASMC) scheme. However, this estimation algorithm is always a positive value so that tracking errors introduced by any uncertainty will cause the estimated bound increase even to infinity with time. Therefore, it further designs an adaptive fuzzy-neural-network control (AFNNC) scheme by imitating the SMC strategy for the maglev transportation system. In the model-free AFNNC, online learning algorithms are designed to cope with the problem of chattering phenomena caused by the sign action in SMC design, and to ensure the stability of the controlled system without the requirement of auxiliary compensated controllers despite the existence of uncertainties. The outputs of the AFNNC scheme can be directly supplied to the electromagnets and LIM without complicated control transformations for relaxing strict constrains in conventional model-based control methodologies. The effectiveness of the proposed control schemes for the maglev transportation system is verified by numerical simulations, and the superiority of the AFNNC scheme is indicated in comparison with the SMC and ASMC strategies.

  20. Geometry control in prestressed adaptive space trusses

    NASA Astrophysics Data System (ADS)

    Sener, Murat; Utku, Senol; Wada, Ben K.

    1993-04-01

    In this work the actuator placement problem for the precision control in prestressed adaptive space trusses is studied. These structures cannot be statically determinate, implying that the length-adjusting actuators have to work against the existing prestressing forces, and also against the stresses caused by the actuation. This type of difficulties does not exist in statically determinate adaptive trusses where, except for overcoming the friction, the actuators operate under zero axial force, and require almost no energy. The actuator placement problem in statically inderterminate trusses is, therefore, governed seriously by the energy and the strength requirements. The paper provides various methodologies for the actuator placement problem in prestressed space trusses.

  1. Readapting the adaptive immune response - therapeutic strategies for atherosclerosis.

    PubMed

    Sage, Andrew P; Mallat, Ziad

    2017-01-04

    Cardiovascular diseases remain a major global health issue, with the development of atherosclerosis as a major underlying cause. Our treatment of cardiovascular disease has improved greatly over the past three decades, but much remains to be done reduce disease burden. Current priorities include reducing atherosclerosis advancement to clinically significant stages and preventing plaque rupture or erosion. Inflammation and involvement of the adaptive immune system influences all these aspects and therefore is one focus for future therapeutic development. The atherosclerotic vascular wall is now recognized to be invaded from both sides (arterial lumen and adventitia), for better or worse, by the adaptive immune system. Atherosclerosis is also affected at several stages by adaptive immune responses, overall providing many opportunities to target these responses and to reduce disease progression. Protective influences that may be defective in diseased individuals include humoral responses to modified LDL and regulatory T cell responses. There are many strategies in development to boost these pathways in humans, including vaccine-based therapies. The effects of various existing adaptive immune targeting therapies, such as blocking critical co-stimulatory pathways or B cell depletion, on cardiovascular disease are beginning to emerge with important consequences for both autoimmune disease patients and the potential for wider use of such therapies. Entering the translation phase for adaptive immune targeting therapies is an exciting and promising prospect.

  2. Fire risk and adaptation strategies in Northern Eurasian forests

    NASA Astrophysics Data System (ADS)

    Shvidenko, Anatoly; Schepaschenko, Dmitry

    2013-04-01

    permafrost areas. Overall, Russia should expect a disproportionate escalation of fire regimes compared to increasing climatic fire danger. Thus, development and implementation of an efficient adaptation strategy is a pressing problem of current forest management of the country. An appropriate system of forest fire protection which would be able to meet challenges of future climates is a corner stone of such a strategy. We consider possible systems solutions of this complex problem including (1) integrated ecological and socio-economic analysis of current and future fire regimes; (2) regional requirements to and specific features of a new paradigm of forest fire protection in the boreal zone of Northern Eurasia; (3) anticipatory strategy of the prevention of large-scale disturbances in forests, including adaptation of forest landscapes to the future climates (regulation of tree composition; setup of relevant spatial structure of forest landscapes; etc.); (4) implementation of an effective system of forest monitoring as part of integrated observing systems; (5) transition to ecologically-friendly systems of industrial development of northern territories; (6) development of new/ improvement of existing legislation and institutional frameworks of forest management which would be satisfactory to react on challenges of climate change; and (6) international cooperation.

  3. [Control strategies against Varroa mites].

    PubMed

    Lodesani, M

    2004-06-01

    In many cases, the easiest way to control a pest or a pathogen is to resort to chemical treatments. In the short period this option is often the most convenient economically and usually does not require refined knowledge of the biology of the pest. Many efforts have been directed to develop chemical treatments against Varroa destructor Anderson & Trueman. Nowadays, product based on organic acids, essential oils, pyrethroids, organophosphate, and formamidine are available. Resistance is serious problem in the chemotherapy of parasites and pathogens of the honeybee. High-level resistance to several active substances (the pyrethroids acrinathrin, flumethrin, fluvalinate; the organophosphate coumaphos; the formamidine amitraz) was detected with laboratory assays in different varroa populations and caused failure of the control in the field. At the end of the '80s, products based on pyrethroids, very effective against the mite, but without any appreciable side effect on bees, became available. Resistance to fluvalinate in Italy and later in other countries caused serious damage to beekeeping; early detection was crucial to reduce losses. The problem of developing suitable treatments was difficult in the case of the varroa mite because most substances active against V. destructor have unacceptable side effects on bees. The idea that the mite could be controlled indefinitely with these strategies began to gain ground.

  4. 76 FR 30193 - National Fish, Wildlife, and Plants Climate Adaptation Strategy; Notice of Intent: Request for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-24

    ... Fish and Wildlife Service National Fish, Wildlife, and Plants Climate Adaptation Strategy; Notice of... National Fish, Wildlife, and Plants Climate Adaptation Strategy (Strategy). The Strategy will provide a... ensure that we are able to consider your comments and information as we develop our draft strategy...

  5. Adaptive control of Space Station with control moment gyros

    NASA Technical Reports Server (NTRS)

    Bishop, Robert H.; Paynter, Scott J.; Sunkel, John W.

    1992-01-01

    An adaptive approach to Space Station attitude control is investigated. The main components of the controller are the parameter identification scheme, the control gain calculation, and the control law. The control law is a full-state feedback space station baseline control law. The control gain calculation is based on linear-quadratic regulator theory with eigenvalues placement in a vertical strip. The parameter identification scheme is a recursive extended Kalman filter that estimates the inertias and also provides an estimate of the unmodeled disturbances due to the aerodynamic torques and to the nonlinear effects. An analysis of the inertia estimation problem suggests that it is possible to estimate Space Station inertias accurately during nominal control moment gyro operations. The closed-loop adaptive control law is shown to be capable of stabilizing the Space Station after large inertia changes. Results are presented for the pitch axis.

  6. Active vibration isolation by adaptive proportional control

    NASA Astrophysics Data System (ADS)

    Liu, Yun-Hui; Wu, Wei-Hao; Chu, Chih-Liang

    2013-01-01

    An active vibration isolation system that applies proportional controller incorporated with an adaptive filter to reduce the transmission of base excitations to a precision instrument is proposed in this work. The absolute vibration velocity signal acquired from an accelerator and being processed through an integrator is input to the controller as a feedback signal, and the controller output signal drives the voice coil actuator to produce a sky-hook damper force. In practice, the phase response of integrator at low frequency such as 2~5 Hz deviate from the 90 degree which is the exact phase difference between the vibration velocity and acceleration. Therefore, an adaptive filter is used to compensate the phase error in this paper. An analysis of this active vibration isolation system is presented, and model predictions are compared to experimental results. The results show that the proposed method significantly reduces transmissibility at resonance without the penalty of increased transmissibility at higher frequencies.

  7. Adaptive electric field control of epileptic seizures.

    PubMed

    Gluckman, B J; Nguyen, H; Weinstein, S L; Schiff, S J

    2001-01-15

    We describe a novel method of adaptively controlling epileptic seizure-like events in hippocampal brain slices using electric fields. Extracellular neuronal activity is continuously recorded during field application through differential extracellular recording techniques, and the applied electric field strength is continuously updated using a computer-controlled proportional feedback algorithm. This approach appears capable of sustained amelioration of seizure events in this preparation when used with negative feedback. Seizures can be induced or enhanced by using fields of opposite polarity through positive feedback. In negative feedback mode, such findings may offer a novel technology for seizure control. In positive feedback mode, adaptively applied electric fields may offer a more physiological means of neural modulation for prosthetic purposes than previously possible.

  8. The Effects of the Locus of CAI Control Strategies on the Learning of Mathematics Rules.

    ERIC Educational Resources Information Center

    Goetzfried, Leslie; Hannafin, Michael J.

    1985-01-01

    Effects of the locus of computer assisted instruction (CAI) strategies on low achievers' learning accuracy and efficiency were studied. Externally controlled adaptive, individually based learner control with advisement, and linear control design strategies were used. Effects were examined for CAI strategy, prior achievement, and sex of student.…

  9. 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.

  10. Surface Force Strategy: Return to Sea Control

    DTIC Science & Technology

    2016-01-01

    trategy orce urfaceS F S Return to Sea Control Surface Force Strategy Return to Sea Control 14 Return to Sea Control Return to Sea Control A quarter...Responding to the call to “strengthen naval power at and from the sea,” the U.S. Naval Surface Force submits this “Surface Force Strategy .” The... strategy describes the return to sea control and implementation of Distributed Lethality as an operational and organizational principle for achieving

  11. Paradoxical cardiovascular effects of implementing adaptive emotion regulation strategies in generalized anxiety disorder.

    PubMed

    Aldao, Amelia; Mennin, Douglas S

    2012-02-01

    Recent models of generalized anxiety disorder (GAD) have expanded on Borkovec's avoidance theory by delineating emotion regulation deficits associated with the excessive worry characteristic of this disorder (see Behar, DiMarco, Hekler, Mohlman, & Staples, 2009). However, it has been difficult to determine whether emotion regulation is simply a useful heuristic for the avoidant properties of worry or an important extension to conceptualizations of GAD. Some of this difficulty may arise from a focus on purported maladaptive regulation strategies, which may be confounded with symptomatic distress components of the disorder (such as worry). We examined the implementation of adaptive regulation strategies by participants with and without a diagnosis of GAD while watching emotion-eliciting film clips. In a between-subjects design, participants were randomly assigned to accept, reappraise, or were not given specific regulation instructions. Implementation of adaptive regulation strategies produced differential effects in the physiological (but not subjective) domain across diagnostic groups. Whereas participants with GAD demonstrated lower cardiac flexibility when implementing adaptive regulation strategies than when not given specific instructions on how to regulate, healthy controls showed the opposite pattern, suggesting they benefited from the use of adaptive regulation strategies. We discuss the implications of these findings for the delineation of emotion regulation deficits in psychopathology. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Stable adaptive control of a class of continuous-flow bioreactors

    SciTech Connect

    Boskovic, J.D.

    1996-01-01

    A stable adaptive control strategy is suggested for a class of continuous-flow bioreactor processes described by Monod kinetics with two unknown parameters, one of which appears nonlinearly. Similarly, as in the case of the previously reported adaptive controllers, the parameterization of the process model, in conjunction with the adaptive exponential feeding strategy and corresponding adaptive algorithms, results in a stable system in which the convergence of the output errors to zero is guaranteed. In the former, however, two major problems are encountered: (1) both output errors were used to adjust the controller parameters, which may yield unacceptable performance of the resulting adaptive system; (2) conditions under which the process output can assume only positive values are difficult to derive. Hence, a design of a stable adaptive controller is suggested, whose parameters are adjusted using only one of the output errors and that yields acceptable performance of the control system. With this method, conditions under which the process outputs can assume only positive values can be readily derived. These conditions in turn guarantee that the control input saturation at value zero cannot occur. In this context, two adaptive controllers are suggested, such that the resulting adaptive systems are stable and the control objective is met. The adaptive controller design relies on a convenient coordinate transformation, while the proof of stability is based on suitably chosen Lyapunov functions. The performance of the adaptive system is evaluated through computer simulations.

  13. Public authority control strategy for opinion evolution in social networks

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Xiong, Xi; Zhang, Minghong; Li, Wei

    2016-08-01

    This paper addresses the need to deal with and control public opinion and rumors. Existing strategies to control public opinion include degree, random, and adaptive bridge control strategies. In this paper, we use the HK model to present a public opinion control strategy based on public authority (PA). This means utilizing the influence of expert or high authority individuals whose opinions we control to obtain the optimum effect in the shortest time possible and thus reach a consensus of public opinion. Public authority (PA) is only influenced by individuals' attributes (age, economic status, and education level) and not their degree distribution; hence, in this paper, we assume that PA complies with two types of public authority distribution (normal and power-law). According to the proposed control strategy, our experiment is based on random, degree, and public authority control strategies in three different social networks (small-world, scale-free, and random) and we compare and analyze the strategies in terms of convergence time (T), final number of controlled agents (C), and comprehensive efficiency (E). We find that different network topologies and the distribution of the PA in the network can influence the final controlling effect. While the effect of PA strategy differs in different network topology structures, all structures achieve comprehensive efficiency with any kind of public authority distribution in any network. Our findings are consistent with several current sociological phenomena and show that in the process of public opinion/rumor control, considerable attention should be paid to high authority individuals.

  14. Function-valued adaptive dynamics and optimal control theory.

    PubMed

    Parvinen, Kalle; Heino, Mikko; Dieckmann, Ulf

    2013-09-01

    In this article we further develop the theory of adaptive dynamics of function-valued traits. Previous work has concentrated on models for which invasion fitness can be written as an integral in which the integrand for each argument value is a function of the strategy value at that argument value only. For this type of models of direct effect, singular strategies can be found using the calculus of variations, with singular strategies needing to satisfy Euler's equation with environmental feedback. In a broader, more mechanistically oriented class of models, the function-valued strategy affects a process described by differential equations, and fitness can be expressed as an integral in which the integrand for each argument value depends both on the strategy and on process variables at that argument value. In general, the calculus of variations cannot help analyzing this much broader class of models. Here we explain how to find singular strategies in this class of process-mediated models using optimal control theory. In particular, we show that singular strategies need to satisfy Pontryagin's maximum principle with environmental feedback. We demonstrate the utility of this approach by studying the evolution of strategies determining seasonal flowering schedules.

  15. An adaptive learning control system for aircraft

    NASA Technical Reports Server (NTRS)

    Mekel, R.; Nachmias, S.

    1976-01-01

    A learning control system is developed which blends the gain scheduling and adaptive control into a single learning system that has the advantages of both. An important feature of the developed learning control system is its capability to adjust the gain schedule in a prescribed manner to account for changing aircraft operating characteristics. Furthermore, if tests performed by the criteria of the learning system preclude any possible change in the gain schedule, then the overall system becomes an ordinary gain scheduling system. Examples are discussed.

  16. Improvement of Adaptive Cruise Control Performance

    NASA Astrophysics Data System (ADS)

    Miyata, Shigeharu; Nakagami, Takashi; Kobayashi, Sei; Izumi, Tomoji; Naito, Hisayoshi; Yanou, Akira; Nakamura, Hitomi; Takehara, Shin

    2010-12-01

    This paper describes the Adaptive Cruise Control system (ACC), a system which reduces the driving burden on the driver. The ACC system primarily supports four driving modes on the road and controls the acceleration and deceleration of the vehicle in order to maintain a set speed or to avoid a crash. This paper proposes more accurate methods of detecting the preceding vehicle by radar while cornering, with consideration for the vehicle sideslip angle, and also of controlling the distance between vehicles. By making full use of the proposed identification logic for preceding vehicles and path estimation logic, an improvement in driving stability was achieved.

  17. Managing Work and Family: Do Control Strategies Help?

    ERIC Educational Resources Information Center

    Versey, H. Shellae

    2015-01-01

    How can we effectively manage competing obligations from work and family without becoming overwhelmed? This question inspires the current study by examining control strategies that may facilitate better work-life balance, with a specific focus on the role of lowered aspirations and positive reappraisals, attitudes that underlie adaptive coping…

  18. Managing Work and Family: Do Control Strategies Help?

    ERIC Educational Resources Information Center

    Versey, H. Shellae

    2015-01-01

    How can we effectively manage competing obligations from work and family without becoming overwhelmed? This question inspires the current study by examining control strategies that may facilitate better work-life balance, with a specific focus on the role of lowered aspirations and positive reappraisals, attitudes that underlie adaptive coping…

  19. Multi-vehicle target selection for adaptive cruise control

    NASA Astrophysics Data System (ADS)

    Moon, Seungwuk; Kang, Hyoung-Jin; Yi, Kyongsu

    2010-11-01

    This paper presents a target selection strategy for adaptive cruise control (ACC) in multiple vehicle traffic situations. Since there are many vehicles in a real road and various transitions between the subject vehicle and the neighbouring vehicles occurred, it is important to establish a target selection and a control strategy for applying the ACC system to multiple vehicle traffic scenes in order to improve the driver acceptance and the vehicle safety. For this purpose, it is necessary to determine which neighbouring vehicle is an important target for the adaptive cruise control and prevention of collision depending on a driving situation. A primary target selection algorithm decides an in-lane target and provides the information to a longitudinal controller in order to drive a subject vehicle smoothly and to ensure safety in multi-vehicle traffic situations. The proposed selection algorithm consists of an in-lane target detection, a motion-based analysis and an integration process. The performance and safety benefits of a multi-vehicle ACC system with proposed target selection strategy are investigated via simulations using several driving scenarios. Simulation results show that the system response is smooth and safe even in multiple vehicle driving situations.

  20. A reduced energy supply strategy in active vibration control

    NASA Astrophysics Data System (ADS)

    Ichchou, M. N.; Loukil, T.; Bareille, O.; Chamberland, G.; Qiu, J.

    2011-12-01

    In this paper, a control strategy is presented and numerically tested. This strategy aims to achieve the potential performance of fully active systems with a reduced energy supply. These energy needs are expected to be comparable to the power demands of semi-active systems, while system performance is intended to be comparable to that of a fully active configuration. The underlying strategy is called 'global semi-active control'. This control approach results from an energy investigation based on management of the optimal control process. Energy management encompasses storage and convenient restitution. The proposed strategy monitors a given active law without any external energy supply by considering purely dissipative and energy-demanding phases. Such a control law is offered here along with an analysis of its properties. A suboptimal form, well adapted for practical implementation steps, is also given. Moreover, a number of numerical experiments are proposed in order to validate test findings.

  1. F-8C adaptive flight control laws

    NASA Technical Reports Server (NTRS)

    Hartmann, G. L.; Harvey, C. A.; Stein, G.; Carlson, D. N.; Hendrick, R. C.

    1977-01-01

    Three candidate digital adaptive control laws were designed for NASA's F-8C digital flyby wire aircraft. Each design used the same control laws but adjusted the gains with a different adaptative algorithm. The three adaptive concepts were: high-gain limit cycle, Liapunov-stable model tracking, and maximum likelihood estimation. Sensors were restricted to conventional inertial instruments (rate gyros and accelerometers) without use of air-data measurements. Performance, growth potential, and computer requirements were used as criteria for selecting the most promising of these candidates for further refinement. The maximum likelihood concept was selected primarily because it offers the greatest potential for identifying several aircraft parameters and hence for improved control performance in future aircraft application. In terms of identification and gain adjustment accuracy, the MLE design is slightly superior to the other two, but this has no significant effects on the control performance achievable with the F-8C aircraft. The maximum likelihood design is recommended for flight test, and several refinements to that design are proposed.

  2. Adaptive wing and flow control technology

    NASA Astrophysics Data System (ADS)

    Stanewsky, E.

    2001-10-01

    The development of the boundary layer and the interaction of the boundary layer with the outer “inviscid” flow field, exacerbated at high speed by the occurrence of shock waves, essentially determine the performance boundaries of high-speed flight. Furthermore, flight and freestream conditions may change considerably during an aircraft mission while the aircraft itself is only designed for multiple but fixed design points thus impairing overall performance. Consequently, flow and boundary layer control and adaptive wing technology may have revolutionary new benefits for take-off, landing and cruise operating conditions for many aircraft by enabling real-time effective geometry optimization relative to the flight conditions. In this paper we will consider various conventional and novel means of boundary layer and flow control applied to moderate-to-large aspect ratio wings, delta wings and bodies with the specific objectives of drag reduction, lift enhancement, separation suppression and the improvement of air-vehicle control effectiveness. In addition, adaptive wing concepts of varying complexity and corresponding aerodynamic performance gains will be discussed, also giving some examples of possible structural realizations. Furthermore, penalties associated with the implementation of control and adaptation mechanisms into actual aircraft will be addressed. Note that the present contribution is rather application oriented.

  3. Geometric view of adaptive optics control

    NASA Astrophysics Data System (ADS)

    Wiberg, Donald M.; Max, Claire E.; Gavel, Donald T.

    2005-05-01

    The objective of an astronomical adaptive optics control system is to minimize the residual wave-front error remaining on the science-object wave fronts after being compensated for atmospheric turbulence and telescope aberrations. Minimizing the mean square wave-front residual maximizes the Strehl ratio and the encircled energy in pointlike images and maximizes the contrast and resolution of extended images. We prove the separation principle of optimal control for application to adaptive optics so as to minimize the mean square wave-front residual. This shows that the residual wave-front error attributable to the control system can be decomposed into three independent terms that can be treated separately in design. The first term depends on the geometry of the wave-front sensor(s), the second term depends on the geometry of the deformable mirror(s), and the third term is a stochastic term that depends on the signal-to-noise ratio. The geometric view comes from understanding that the underlying quantity of interest, the wave-front phase surface, is really an infinite-dimensional vector within a Hilbert space and that this vector space is projected into subspaces we can control and measure by the deformable mirrors and wave-front sensors, respectively. When the control and estimation algorithms are optimal, the residual wave front is in a subspace that is the union of subspaces orthogonal to both of these projections. The method is general in that it applies both to conventional (on-axis, ground-layer conjugate) adaptive optics architectures and to more complicated multi-guide-star- and multiconjugate-layer architectures envisaged for future giant telescopes. We illustrate the approach by using a simple example that has been worked out previously [J. Opt. Soc. Am. A73, 1171 (1983)] for a single-conjugate, static atmosphere case and follow up with a discussion of how it is extendable to general adaptive optics architectures.

  4. Adaptation of enzymes to temperature: searching for basic "strategies".

    PubMed

    Somero, George N

    2004-11-01

    The pervasive influence of temperature on biological systems necessitates a suite of temperature--compensatory adaptations that span all levels of biological organization--from behavior to fine-scale molecular structure. Beginning about 50 years ago, physiological studies conducted with whole organisms or isolated tissues, by such pioneers of comparative thermal physiology as V.Ya. Alexandrov, T.H. Bullock, F.E.J. Fry, H. Precht, C.L. Prosser, and P.F. Scholander, began to document in detail the abilities of ectothermic animals to sustain relatively similar rates of metabolic activity at widely different temperatures of adaptation or acclimation. These studies naturally led to investigation of the roles played by enzymatic proteins in metabolic temperature compensation. Peter Hochachka's laboratory became an epicenter of this new focus in comparative physiology. The studies of the enzyme lactate dehydrogenase (LDH) that he initiated as a PhD student at Duke University in the mid-1960s and continued for several years at the University of British Columbia laid much of the foundation for subsequent studies of protein adaptation to temperature. Studies of orthologs of LDH have revealed the importance of conserving kinetic properties (catalytic rate constants (kcat) and Michaelis-Menten constants (Km) and structural stability during adaptation to temperature, and recently have identified the types of amino acid substitutions causing this adaptive variation. The roles of pH and low-molecular-mass organic solutes (osmolytes) in conserving the functional and structural properties of enzymes also have been elucidated using LDH. These studies, begun in Peter Hochachka's laboratory almost 40 years ago, have been instrumental in the development of a conceptual framework for the study of biochemical adaptation, a field whose origin can be traced largely to his creative influences. This framework emphasizes the complementary roles of three "strategies" of adaptation: (1) changes

  5. Adaptive impedance control of redundant manipulators

    NASA Technical Reports Server (NTRS)

    Colbaugh, R.; Glass, K.; Seraji, H.

    1990-01-01

    A scheme for controlling the mechanical impedance of the end-effector of a kinematically redundant manipulator is presented. The proposed control system consists of two subsystems: an adaptive impedance controller which generates the Cartesian-space control input F (is a member of Rm) required to provide the desired end-effector impedance characteristics, and an algorithm that maps this control input to the joint torque T (is a member of Rn). The F to T map is constructed so that the robot redundancy is utilized to improve either the kinematic or dynamic performance of the robot. The impedance controller does not require knowledge of the complex robot dynamic model or parameter values for the robot, the payload, or the environment, and is implemented without calculation of the robot inverse kinematic transformation. As a result, the scheme is very general and is computationally efficient for on-line implementation.

  6. Model reference adaptive control of robots

    NASA Technical Reports Server (NTRS)

    Steinvorth, Rodrigo

    1991-01-01

    This project presents the results of controlling two types of robots using new Command Generator Tracker (CGT) based Direct Model Reference Adaptive Control (MRAC) algorithms. Two mathematical models were used to represent a single-link, flexible joint arm and a Unimation PUMA 560 arm; and these were then controlled in simulation using different MRAC algorithms. Special attention was given to the performance of the algorithms in the presence of sudden changes in the robot load. Previously used CGT based MRAC algorithms had several problems. The original algorithm that was developed guaranteed asymptotic stability only for almost strictly positive real (ASPR) plants. This condition is very restrictive, since most systems do not satisfy this assumption. Further developments to the algorithm led to an expansion of the number of plants that could be controlled, however, a steady state error was introduced in the response. These problems led to the introduction of some modifications to the algorithms so that they would be able to control a wider class of plants and at the same time would asymptotically track the reference model. This project presents the development of two algorithms that achieve the desired results and simulates the control of the two robots mentioned before. The results of the simulations are satisfactory and show that the problems stated above have been corrected in the new algorithms. In addition, the responses obtained show that the adaptively controlled processes are resistant to sudden changes in the load.

  7. Adaptive control based on retrospective cost optimization

    NASA Technical Reports Server (NTRS)

    Santillo, Mario A. (Inventor); Bernstein, Dennis S. (Inventor)

    2012-01-01

    A discrete-time adaptive control law for stabilization, command following, and disturbance rejection that is effective for systems that are unstable, MIMO, and/or nonminimum phase. The adaptive control algorithm includes guidelines concerning the modeling information needed for implementation. This information includes the relative degree, the first nonzero Markov parameter, and the nonminimum-phase zeros. Except when the plant has nonminimum-phase zeros whose absolute value is less than the plant's spectral radius, the required zero information can be approximated by a sufficient number of Markov parameters. No additional information about the poles or zeros need be known. Numerical examples are presented to illustrate the algorithm's effectiveness in handling systems with errors in the required modeling data, unknown latency, sensor noise, and saturation.

  8. Adaptive Control with Reference Model Modification

    NASA Technical Reports Server (NTRS)

    Stepanyan, Vahram; Krishnakumar, Kalmanje

    2012-01-01

    This paper presents a modification of the conventional model reference adaptive control (MRAC) architecture in order to improve transient performance of the input and output signals of uncertain systems. A simple modification of the reference model is proposed by feeding back the tracking error signal. It is shown that the proposed approach guarantees tracking of the given reference command and the reference control signal (one that would be designed if the system were known) not only asymptotically but also in transient. Moreover, it prevents generation of high frequency oscillations, which are unavoidable in conventional MRAC systems for large adaptation rates. The provided design guideline makes it possible to track a reference commands of any magnitude from any initial position without re-tuning. The benefits of the method are demonstrated with a simulation example

  9. Block adaptive rate controlled image data compression

    NASA Technical Reports Server (NTRS)

    Rice, R. F.; Hilbert, E.; Lee, J.-J.; Schlutsmeyer, A.

    1979-01-01

    A block adaptive rate controlled (BARC) image data compression algorithm is described. It is noted that in the algorithm's principal rate controlled mode, image lines can be coded at selected rates by combining practical universal noiseless coding techniques with block adaptive adjustments in linear quantization. Compression of any source data at chosen rates of 3.0 bits/sample and above can be expected to yield visual image quality with imperceptible degradation. Exact reconstruction will be obtained if the one-dimensional difference entropy is below the selected compression rate. It is noted that the compressor can also be operated as a floating rate noiseless coder by simply not altering the input data quantization. Here, the universal noiseless coder ensures that the code rate is always close to the entropy. Application of BARC image data compression to the Galileo orbiter mission of Jupiter is considered.

  10. Materials for Adaptive Structural Acoustic Controls

    DTIC Science & Technology

    1994-01-31

    stannate -11M I f-I ic cmoiin MATERIALS FOR ADAPTIVE STRUCTURAL ACOUSTIC CONTROLS Period February 1, 1993 to January 31, 1994 Annual Report VOLUME I OFFICE... ics 139, 25- 49(1993). 14. Jiang, Q., W. Cao, and L. E. Cross. Electrical Fatigue in Lead Zirconate Titanate Ceramics. J. Am. Ceram. Soc. 77(1), 211...Ceramic Composte Transducer-The Moonie. Ferroelecuics: IM , Gaithersburg, Maryland (August 1993). 21. Tressler, J. F., Q. C. Xu, S. Yoshikawa, K. Uchino

  11. Applications of Neural Networks to Adaptive Control

    DTIC Science & Technology

    1989-12-01

    DTIC ;- E py 00 NAVAL POSTGRADUATE SCHOOL Monterey, California I.$ RDTIC IELECTE fl THESIS BEG7V°U APPLICATIONS OF NEURAL NETWORKS TO ADAPTIVE CONTROL...Second keader E . Robert Wood, Chairman, Department of Aeronautics and Astronautics Gordoii E . Schacher, Dean of Faculty and Graduate Education ii ABSTRACT...23: Network Dynamic Stability for q(t) . ............................. 55 ix Figure 24: Network Dynamic Stability for e (t

  12. Climate change adaptation strategies for resource management and conservation planning.

    PubMed

    Lawler, Joshua J

    2009-04-01

    Recent rapid changes in the Earth's climate have altered ecological systems around the globe. Global warming has been linked to changes in physiology, phenology, species distributions, interspecific interactions, and disturbance regimes. Projected future climate change will undoubtedly result in even more dramatic shifts in the states of many ecosystems. These shifts will provide one of the largest challenges to natural resource managers and conservation planners. Managing natural resources and ecosystems in the face of uncertain climate requires new approaches. Here, the many adaptation strategies that have been proposed for managing natural systems in a changing climate are reviewed. Most of the recommended approaches are general principles and many are tools that managers are already using. What is new is a turning toward a more agile management perspective. To address climate change, managers will need to act over different spatial and temporal scales. The focus of restoration will need to shift from historic species assemblages to potential future ecosystem services. Active adaptive management based on potential future climate impact scenarios will need to be a part of everyday operations. And triage will likely become a critical option. Although many concepts and tools for addressing climate change have been proposed, key pieces of information are still missing. To successfully manage for climate change, a better understanding will be needed of which species and systems will likely be most affected by climate change, how to preserve and enhance the evolutionary capacity of species, how to implement effective adaptive management in new systems, and perhaps most importantly, in which situations and systems will the general adaptation strategies that have been proposed work and how can they be effectively applied.

  13. Adaptive strategy for multi-user robotic rehabilitation games.

    PubMed

    Caurin, Glauco A P; Siqueira, Adriano A G; Andrade, Kleber O; Joaquim, Ricardo C; Krebs, Hermano I

    2011-01-01

    In this paper, we discuss a strategy for the adaptation of the "difficulty level" in games intended to include motor planning during robotic rehabilitation. We consider concurrently the motivation of the user and his/her performance in a Pong game. User motivation is classified in three levels (not motivated, well motivated and overloaded). User performance is measured as a combination of knowledge of results--achieved goals and score points in the game--and knowledge of performance--joint displacement, speed, aiming, user work, etc. Initial results of a pilot test with unimpaired healthy young volunteers are also presented showing a tendency for individualization of the parameter values.

  14. Strategies of Adaptation: A Soviet Enterprise Under Perestroika and Privatization

    DTIC Science & Technology

    1991-06-01

    the early 1970’s (see Il’in, 1973; Gorlin , 1976), we have referred to it as an enterprise throughout this paper. Strateaies of Adaptation 5 convinced...fact, some refer to it as "Shop 1." "See Il’in (1973) and Gorlin (1976) for a discussion of the policy of consolidating enterprises into production...34edineniia. ( Gorlin , 1976; Il’in, 1973) This was encouraged by the state but it also complemented the enterprise strategy of increasing bargaining power

  15. 78 FR 19514 - National Fish, Wildlife, and Plants Climate Adaptation Strategy

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-01

    ... Fish and Wildlife Service National Fish, Wildlife, and Plants Climate Adaptation Strategy AGENCY: Fish..., Wildlife, and Plants Climate Adaptation Strategy (NFWPCAS or Strategy). The purpose of the Strategy is to... natural systems provide, in a changing climate. Input from public comments and workshops has been...

  16. Neural Control Adaptation to Motor Noise Manipulation

    PubMed Central

    Hasson, Christopher J.; Gelina, Olga; Woo, Garrett

    2016-01-01

    Antagonistic muscular co-activation can compensate for movement variability induced by motor noise at the expense of increased energetic costs. Greater antagonistic co-activation is commonly observed in older adults, which could be an adaptation to increased motor noise. The present study tested this hypothesis by manipulating motor noise in 12 young subjects while they practiced a goal-directed task using a myoelectric virtual arm, which was controlled by their biceps and triceps muscle activity. Motor noise was increased by increasing the coefficient of variation (CV) of the myoelectric signals. As hypothesized, subjects adapted by increasing antagonistic co-activation, and this was associated with reduced noise-induced performance decrements. A second hypothesis was that a virtual decrease in motor noise, achieved by smoothing the myoelectric signals, would have the opposite effect: co-activation would decrease and motor performance would improve. However, the results showed that a decrease in noise made performance worse instead of better, with no change in co-activation. Overall, these findings suggest that the nervous system adapts to virtual increases in motor noise by increasing antagonistic co-activation, and this preserves motor performance. Reducing noise may have failed to benefit performance due to characteristics of the filtering process itself, e.g., delays are introduced and muscle activity bursts are attenuated. The observed adaptations to increased noise may explain in part why older adults and many patient populations have greater antagonistic co-activation, which could represent an adaptation to increased motor noise, along with a desire for increased joint stability. PMID:26973487

  17. Genetic Adaptive Control for PZT Actuators

    NASA Technical Reports Server (NTRS)

    Kim, Jeongwook; Stover, Shelley K.; Madisetti, Vijay K.

    1995-01-01

    A piezoelectric transducer (PZT) is capable of providing linear motion if controlled correctly and could provide a replacement for traditional heavy and large servo systems using motors. This paper focuses on a genetic model reference adaptive control technique (GMRAC) for a PZT which is moving a mirror where the goal is to keep the mirror velocity constant. Genetic Algorithms (GAs) are an integral part of the GMRAC technique acting as the search engine for an optimal PID controller. Two methods are suggested to control the actuator in this research. The first one is to change the PID parameters and the other is to add an additional reference input in the system. The simulation results of these two methods are compared. Simulated Annealing (SA) is also used to solve the problem. Simulation results of GAs and SA are compared after simulation. GAs show the best result according to the simulation results. The entire model is designed using the Mathworks' Simulink tool.

  18. Spacecraft attitude control using direct model reference adaptive control

    NASA Astrophysics Data System (ADS)

    Harvey, Seth A.

    This research began in the summer of 2006. During that summer a method was developed to estimate the gravity gradient as well as the nadir vector of a Plug-and-Play [PNP] satellite. This was done based on the assumptions that there were perturbations in the satellite model that kept the satellite from knowing this information a priori. An indirect adaptive estimation scheme was used to accomplish this goal. However it is impractical to do this for each perturbation in the plant. By the very nature of PNP Satellites, there could be errors in among other things, reaction wheel mounting/orientation, star tracker location/orientation, satellite center of mass (COM), and payload location/orientation. An adaptive scheme to estimate each error is not efficient and ultimately is not the goal. The goal is to accurately control the satellite despite the numerous and possibly large errors inherent in PNP Satellite models. Instead of using indirect adaptive methods to gain precise knowledge of the plant, direct adaptive control methods will be used to overcome the errors of the plant and gain precise control of the satellite. One way of overcoming the inaccuracies of the model is to assume the spacecraft dynamics are largely unknown. A shift in philosophy was then taken from indirect adaptive methods to direct methods. Direct Reference and Model Reference Adaptive Controller [DRAC & DMRAC] are then developed that will precisely and robustly control the attitude of a PNP satellite. The benefits demonstrated by the DMRAC methodologies extend well past plug and play satellites and could be utilized in any space application.

  19. Adaptive Test Schemes for Control of Paratuberculosis in Dairy Cows.

    PubMed

    Kirkeby, Carsten; Græsbøll, Kaare; Nielsen, Søren Saxmose; Christiansen, Lasse Engbo; Toft, Nils; Halasa, Tariq

    2016-01-01

    Paratuberculosis is a chronic infection that in dairy cattle causes reduced milk yield, weight loss, and ultimately fatal diarrhea. Subclinical animals can excrete bacteria (Mycobacterium avium ssp. paratuberculosis, MAP) in feces and infect other animals. Farmers identify the infectious animals through a variety of test-strategies, but are challenged by the lack of perfect tests. Frequent testing increases the sensitivity but the costs of testing are a cause of concern for farmers. Here, we used a herd simulation model using milk ELISA tests to evaluate the epidemiological and economic consequences of continuously adapting the sampling interval in response to the estimated true prevalence in the herd. The key results were that the true prevalence was greatly affected by the hygiene level and to some extent by the test-frequency. Furthermore, the choice of prevalence that will be tolerated in a control scenario had a major impact on the true prevalence in the normal hygiene setting, but less so when the hygiene was poor. The net revenue is not greatly affected by the test-strategy, because of the general variation in net revenues between farms. An exception to this is the low hygiene herd, where frequent testing results in lower revenue. When we look at the probability of eradication, then it is correlated with the testing frequency and the target prevalence during the control phase. The probability of eradication is low in the low hygiene herd, and a test-and-cull strategy should probably not be the primary strategy in this herd. Based on this study we suggest that, in order to control MAP, the standard Danish dairy farm should use an adaptive strategy where a short sampling interval of three months is used when the estimated true prevalence is above 1%, and otherwise use a long sampling interval of one year.

  20. Adaptive Test Schemes for Control of Paratuberculosis in Dairy Cows

    PubMed Central

    Græsbøll, Kaare; Nielsen, Søren Saxmose; Christiansen, Lasse Engbo; Toft, Nils; Halasa, Tariq

    2016-01-01

    Paratuberculosis is a chronic infection that in dairy cattle causes reduced milk yield, weight loss, and ultimately fatal diarrhea. Subclinical animals can excrete bacteria (Mycobacterium avium ssp. paratuberculosis, MAP) in feces and infect other animals. Farmers identify the infectious animals through a variety of test-strategies, but are challenged by the lack of perfect tests. Frequent testing increases the sensitivity but the costs of testing are a cause of concern for farmers. Here, we used a herd simulation model using milk ELISA tests to evaluate the epidemiological and economic consequences of continuously adapting the sampling interval in response to the estimated true prevalence in the herd. The key results were that the true prevalence was greatly affected by the hygiene level and to some extent by the test-frequency. Furthermore, the choice of prevalence that will be tolerated in a control scenario had a major impact on the true prevalence in the normal hygiene setting, but less so when the hygiene was poor. The net revenue is not greatly affected by the test-strategy, because of the general variation in net revenues between farms. An exception to this is the low hygiene herd, where frequent testing results in lower revenue. When we look at the probability of eradication, then it is correlated with the testing frequency and the target prevalence during the control phase. The probability of eradication is low in the low hygiene herd, and a test-and-cull strategy should probably not be the primary strategy in this herd. Based on this study we suggest that, in order to control MAP, the standard Danish dairy farm should use an adaptive strategy where a short sampling interval of three months is used when the estimated true prevalence is above 1%, and otherwise use a long sampling interval of one year. PMID:27907192

  1. Adaptive control of force microscope cantilever dynamics

    NASA Astrophysics Data System (ADS)

    Jensen, S. E.; Dougherty, W. M.; Garbini, J. L.; Sidles, J. A.

    2007-09-01

    Magnetic resonance force microscopy (MRFM) and other emerging scanning probe microscopies entail the detection of attonewton-scale forces. Requisite force sensitivities are achieved through the use of soft force microscope cantilevers as high resonant-Q micromechanical oscillators. In practice, the dynamics of these oscillators are greatly improved by the application of force feedback control computed in real time by a digital signal processor (DSP). Improvements include increased sensitive bandwidth, reduced oscillator ring up/down time, and reduced cantilever thermal vibration amplitude. However, when the cantilever tip and the sample are in close proximity, electrostatic and Casimir tip-sample force gradients can significantly alter the cantilever resonance frequency, foiling fixed-gain narrow-band control schemes. We report an improved, adaptive control algorithm that uses a Hilbert transform technique to continuously measure the vibration frequency of the thermally-excited cantilever and seamlessly adjust the DSP program coefficients. The closed-loop vibration amplitude is typically 0.05 nm. This adaptive algorithm enables narrow-band formally-optimal control over a wide range of resonance frequencies, and preserves the thermally-limited signal to noise ratio (SNR).

  2. Design of Sequentially Randomized Trials for Testing Adaptive Treatment Strategies

    PubMed Central

    Ogbagaber, Semhar B.; Karp, Jordan; Wahed, Abdus S.

    2016-01-01

    An adaptive treatment strategy (ATS) is an outcome-guided algorithm that allows personalized treatment of complex diseases based on patients’ disease status and treatment history. Conditions such as AIDS, depression, and cancer usually require several stages of treatment due to the chronic, multifactorial nature of illness progression and management. Sequential multiple assignment randomized (SMAR) designs permit simultaneous inference about multiple ATSs, where patients are sequentially randomized to treatments at different stages depending upon response status. The purpose of the article is to develop a sample size formula to ensure adequate power for comparing two or more ATSs. Based on a Wald-type statistic for comparing multiple ATSs with a continuous endpoint, we develop a sample size formula and test it through simulation studies. We show via simulation that the proposed sample size formula maintains the nominal power. The proposed sample size formula is not applicable to designs with time-to-event endpoints but the formula will be useful for practitioners while designing SMAR trials to compare adaptive treatment strategies. PMID:26412033

  3. MTPA control of mechanical sensorless IPMSM based on adaptive nonlinear control.

    PubMed

    Najjar-Khodabakhsh, Abbas; Soltani, Jafar

    2016-03-01

    In this paper, an adaptive nonlinear control scheme has been proposed for implementing maximum torque per ampere (MTPA) control strategy corresponding to interior permanent magnet synchronous motor (IPMSM) drive. This control scheme is developed in the rotor d-q axis reference frame using adaptive input-output state feedback linearization (AIOFL) method. The drive system control stability is supported by Lyapunov theory. The motor inductances are online estimated by an estimation law obtained by AIOFL. The estimation errors of these parameters are proved to be asymptotically converged to zero. Based on minimizing the motor current amplitude, the MTPA control strategy is performed by using the nonlinear optimization technique while considering the online reference torque. The motor reference torque is generated by a conventional rotor speed PI controller. By performing MTPA control strategy, the generated online motor d-q reference currents were used in AIOFL controller to obtain the SV-PWM reference voltages and the online estimation of the motor d-q inductances. In addition, the stator resistance is online estimated using a conventional PI controller. Moreover, the rotor position is detected using the online estimation of the stator flux and online estimation of the motor q-axis inductance. Simulation and experimental results obtained prove the effectiveness and the capability of the proposed control method.

  4. Simple adaptive control system design for a quadrotor with an internal PFC

    SciTech Connect

    Mizumoto, Ikuro; Nakamura, Takuto; Kumon, Makoto; Takagi, Taro

    2014-12-10

    The paper deals with an adaptive control system design problem for a four rotor helicopter or quadrotor. A simple adaptive control design scheme with a parallel feedforward compensator (PFC) in the internal loop of the considered quadrotor will be proposed based on the backstepping strategy. As is well known, the backstepping control strategy is one of the advanced control strategy for nonlinear systems. However, the control algorithm will become complex if the system has higher order relative degrees. We will show that one can skip some design steps of the backstepping method by introducing a PFC in the inner loop of the considered quadrotor, so that the structure of the obtained controller will be simplified and a high gain based adaptive feedback control system will be designed. The effectiveness of the proposed method will be confirmed through numerical simulations.

  5. Nonlinear Adaptive PID Control for Greenhouse Environment Based on RBF Network

    PubMed Central

    Zeng, Songwei; Hu, Haigen; Xu, Lihong; Li, Guanghui

    2012-01-01

    This paper presents a hybrid control strategy, combining Radial Basis Function (RBF) network with conventional proportional, integral, and derivative (PID) controllers, for the greenhouse climate control. A model of nonlinear conservation laws of enthalpy and matter between numerous system variables affecting the greenhouse climate is formulated. RBF network is used to tune and identify all PID gain parameters online and adaptively. The presented Neuro-PID control scheme is validated through simulations of set-point tracking and disturbance rejection. We compare the proposed adaptive online tuning method with the offline tuning scheme that employs Genetic Algorithm (GA) to search the optimal gain parameters. The results show that the proposed strategy has good adaptability, strong robustness and real-time performance while achieving satisfactory control performance for the complex and nonlinear greenhouse climate control system, and it may provide a valuable reference to formulate environmental control strategies for actual application in greenhouse production. PMID:22778587

  6. Nonlinear adaptive PID control for greenhouse environment based on RBF network.

    PubMed

    Zeng, Songwei; Hu, Haigen; Xu, Lihong; Li, Guanghui

    2012-01-01

    This paper presents a hybrid control strategy, combining Radial Basis Function (RBF) network with conventional proportional, integral, and derivative (PID) controllers, for the greenhouse climate control. A model of nonlinear conservation laws of enthalpy and matter between numerous system variables affecting the greenhouse climate is formulated. RBF network is used to tune and identify all PID gain parameters online and adaptively. The presented Neuro-PID control scheme is validated through simulations of set-point tracking and disturbance rejection. We compare the proposed adaptive online tuning method with the offline tuning scheme that employs Genetic Algorithm (GA) to search the optimal gain parameters. The results show that the proposed strategy has good adaptability, strong robustness and real-time performance while achieving satisfactory control performance for the complex and nonlinear greenhouse climate control system, and it may provide a valuable reference to formulate environmental control strategies for actual application in greenhouse production.

  7. High-speed train control based on multiple-model adaptive control with second-level adaptation

    NASA Astrophysics Data System (ADS)

    Zhou, Yonghua; Zhang, Zhenlin

    2014-05-01

    Speed uplift has become the leading trend for the development of current railway traffic. Ideally, under the high-speed transportation infrastructure, trains run at specified positions with designated speeds at appointed times. In view of the faster adaptation ability of multiple-model adaptive control with second-level adaptation (MMAC-SLA), we propose one type of MMAC-SLA for a class of nonlinear systems such as cascaded vehicles. By using an input decomposition technique, the corresponding stability proof is solved for the proposed MMAC-SLA, which synthesises the control signals from the weighted multiple models. The control strategy is utilised to challenge the position and speed tracking of high-speed trains with uncertain parameters. The simulation results demonstrate that the proposed MMAC-SLA can achieve small tracking errors with moderate in-train forces incurred under the control of flattening input signals with practical enforceability. This study also provides a new idea for the control of in-train forces by tracking the positions and speeds of cars while considering power constraints.

  8. An adaptive learning control system for large flexible structures

    NASA Technical Reports Server (NTRS)

    Thau, F. E.

    1985-01-01

    The objective of the research has been to study the design of adaptive/learning control systems for the control of large flexible structures. In the first activity an adaptive/learning control methodology for flexible space structures was investigated. The approach was based on using a modal model of the flexible structure dynamics and an output-error identification scheme to identify modal parameters. In the second activity, a least-squares identification scheme was proposed for estimating both modal parameters and modal-to-actuator and modal-to-sensor shape functions. The technique was applied to experimental data obtained from the NASA Langley beam experiment. In the third activity, a separable nonlinear least-squares approach was developed for estimating the number of excited modes, shape functions, modal parameters, and modal amplitude and velocity time functions for a flexible structure. In the final research activity, a dual-adaptive control strategy was developed for regulating the modal dynamics and identifying modal parameters of a flexible structure. A min-max approach was used for finding an input to provide modal parameter identification while not exceeding reasonable bounds on modal displacement.

  9. Adaptive control of a Stewart platform-based manipulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Charles C.; Antrazi, Sami S.; Zhou, Zhen-Lei; Campbell, Charles E., Jr.

    1993-01-01

    A joint-space adaptive control scheme for controlling noncompliant motion of a Stewart platform-based manipulator (SPBM) was implemented in the Hardware Real-Time Emulator at Goddard Space Flight Center. The six-degrees of freedom SPBM uses two platforms and six linear actuators driven by dc motors. The adaptive control scheme is based on proportional-derivative controllers whose gains are adjusted by an adaptation law based on model reference adaptive control and Liapunov direct method. It is concluded that the adaptive control scheme provides superior tracking capability as compared to fixed-gain controllers.

  10. Adaptive control of a Stewart platform-based manipulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Charles C.; Antrazi, Sami S.; Zhou, Zhen-Lei; Campbell, Charles E., Jr.

    1993-01-01

    A joint-space adaptive control scheme for controlling noncompliant motion of a Stewart platform-based manipulator (SPBM) was implemented in the Hardware Real-Time Emulator at Goddard Space Flight Center. The six-degrees of freedom SPBM uses two platforms and six linear actuators driven by dc motors. The adaptive control scheme is based on proportional-derivative controllers whose gains are adjusted by an adaptation law based on model reference adaptive control and Liapunov direct method. It is concluded that the adaptive control scheme provides superior tracking capability as compared to fixed-gain controllers.

  11. Finite element/finite volume approaches with adaptive time stepping strategies for transient thermal problems

    NASA Technical Reports Server (NTRS)

    Mohan, Ram V.; Tamma, Kumar K.

    1993-01-01

    An adaptive time stepping strategy for transient thermal analysis of engineering systems is described which computes the time step based on the local truncation error with a good global error control and obtains optimal time steps to be used during the analysis. Combined mesh partitionings involving FEM/FVM meshes based on physical situations to obtain numerically improved physical representations are also proposed. Numerical test cases are described and comparative pros and cons are identified for practical situations.

  12. Adaptive control of space based robot manipulators

    NASA Technical Reports Server (NTRS)

    Walker, Michael W.; Wee, Liang-Boon

    1991-01-01

    For space based robots in which the base is free to move, motion planning and control is complicated by uncertainties in the inertial properties of the manipulator and its load. A new adaptive control method is presented for space based robots which achieves globally stable trajectory tracking in the presence of uncertainties in the inertial parameters of the system. A partition is made of the fifteen degree of freedom system dynamics into two parts: a nine degree of freedom invertible portion and a six degree of freedom noninvertible portion. The controller is then designed to achieve trajectory tracking of the invertible portion of the system. This portion consist of the manipulator joint positions and the orientation of the base. The motion of the noninvertible portion is bounded, but unpredictable. This portion consist of the position of the robot's base and the position of the reaction wheel.

  13. Adaptive Accommodation Control Method for Complex Assembly

    NASA Astrophysics Data System (ADS)

    Kang, Sungchul; Kim, Munsang; Park, Shinsuk

    Robotic systems have been used to automate assembly tasks in manufacturing and in teleoperation. Conventional robotic systems, however, have been ineffective in controlling contact force in multiple contact states of complex assemblythat involves interactions between complex-shaped parts. Unlike robots, humans excel at complex assembly tasks by utilizing their intrinsic impedance, forces and torque sensation, and tactile contact clues. By examining the human behavior in assembling complex parts, this study proposes a novel geometry-independent control method for robotic assembly using adaptive accommodation (or damping) algorithm. Two important conditions for complex assembly, target approachability and bounded contact force, can be met by the proposed control scheme. It generates target approachable motion that leads the object to move closer to a desired target position, while contact force is kept under a predetermined value. Experimental results from complex assembly tests have confirmed the feasibility and applicability of the proposed method.

  14. Alternative adaptive immunity strategies: coelacanth, cod and shark immunity.

    PubMed

    Buonocore, Francesco; Gerdol, Marco

    2016-01-01

    The advent of high throughput sequencing has permitted to investigate the genome and the transcriptome of novel non-model species with unprecedented depth. This technological advance provided a better understanding of the evolution of adaptive immune genes in gnathostomes, revealing several unexpected features in different fish species which are of particular interest. In the present paper, we review the current understanding of the adaptive immune system of the coelacanth, the elephant shark and the Atlantic cod. The study of coelacanth, the only living extant of the long thought to be extinct Sarcopterygian lineage, is fundamental to bring new insights on the evolution of the immune system in higher vertebrates. Surprisingly, coelacanths are the only known jawed vertebrates to lack IgM, whereas two IgD/W loci are present. Cartilaginous fish are of great interest due to their basal position in the vertebrate tree of life; the genome of the elephant shark revealed the lack of several important immune genes related to T cell functions, which suggest the existence of a primordial set of TH1-like cells. Finally, the Atlantic cod lacks a functional major histocompatibility II complex, but balances this evolutionary loss with the expansion of specific gene families, including MHC I, Toll-like receptors and antimicrobial peptides. Overall, these data point out that several fish species present an unconventional adaptive immune system, but the loss of important immune genes is balanced by adaptive evolutionary strategies which still guarantee the establishment of an efficient immune response against the pathogens they have to fight during their life. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. 2011 National Drug Control Strategy. Executive Summary

    ERIC Educational Resources Information Center

    Office of National Drug Control Policy, 2011

    2011-01-01

    In May of 2010, President Obama released the Administration's inaugural "National Drug Control Strategy", a comprehensive approach to combat the public health and safety consequences posed by drug use. Now, a year later, the Administration is releasing its update building upon that initial "Strategy". The "Strategy" establishes ambitious goals to…

  16. Kalman filter based control for Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Petit, Cyril; Quiros-Pacheco, Fernando; Conan, Jean-Marc; Kulcsár, Caroline; Raynaud, Henri-François; Fusco, Thierry

    2004-12-01

    Classical Adaptive Optics suffer from a limitation of the corrected Field Of View. This drawback has lead to the development of MultiConjugated Adaptive Optics. While the first MCAO experimental set-ups are presently under construction, little attention has been paid to the control loop. This is however a key element in the optimization process especially for MCAO systems. Different approaches have been proposed in recent articles for astronomical applications : simple integrator, Optimized Modal Gain Integrator and Kalman filtering. We study here Kalman filtering which seems a very promising solution. Following the work of Brice Leroux, we focus on a frequential characterization of kalman filters, computing a transfer matrix. The result brings much information about their behaviour and allows comparisons with classical controllers. It also appears that straightforward improvements of the system models can lead to static aberrations and vibrations filtering. Simulation results are proposed and analysed thanks to our frequential characterization. Related problems such as model errors, aliasing effect reduction or experimental implementation and testing of Kalman filter control loop on a simplified MCAO experimental set-up could be then discussed.

  17. 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.

  18. Adaptive neural networks for mobile robotic control

    NASA Astrophysics Data System (ADS)

    Burnett, Jeff R.; Dagli, Cihan H.

    2001-03-01

    Movement of a differential drive robot has non-linear dependence on the current position and orientation. A controller must be able to deal with the non-linearity of the plant. The controller must either linearize the plant and deal with special cases, or be non-linear itself. Once the controller is designed, implementation on a real robotic platform presents challenges due to the varying parameters of the plant. Robots of the same model may have different motor frictions. The surface the robot maneuvers on may change e.g. carpet to tile. Batteries will drain, providing less power over time. A feed-forward neural network controller could overcome these challenges. The network could learn the non- linearities of the plant and monitor the error for parameter changes and adapt to them. In this manner, a single controller can be designed for an ideal robot, and then used to populate a multi-robot colony without manually fine tuning the controller for each robot. This paper shall demonstrate such a controller, outlining design in simulation and implementation on Khepera robotic platforms.

  19. Online Adaptation and Over-Trial Learning in Macaque Visuomotor Control

    PubMed Central

    Braun, Daniel A.; Aertsen, Ad; Paz, Rony; Vaadia, Eilon; Rotter, Stefan; Mehring, Carsten

    2011-01-01

    When faced with unpredictable environments, the human motor system has been shown to develop optimized adaptation strategies that allow for online adaptation during the control process. Such online adaptation is to be contrasted to slower over-trial learning that corresponds to a trial-by-trial update of the movement plan. Here we investigate the interplay of both processes, i.e., online adaptation and over-trial learning, in a visuomotor experiment performed by macaques. We show that simple non-adaptive control schemes fail to perform in this task, but that a previously suggested adaptive optimal feedback control model can explain the observed behavior. We also show that over-trial learning as seen in learning and aftereffect curves can be explained by learning in a radial basis function network. Our results suggest that both the process of over-trial learning and the process of online adaptation are crucial to understand visuomotor learning. PMID:21720526

  20. Adaptive method with intercessory feedback control for an intelligent agent

    DOEpatents

    Goldsmith, Steven Y.

    2004-06-22

    An adaptive architecture method with feedback control for an intelligent agent provides for adaptively integrating reflexive and deliberative responses to a stimulus according to a goal. An adaptive architecture method with feedback control for multiple intelligent agents provides for coordinating and adaptively integrating reflexive and deliberative responses to a stimulus according to a goal. Re-programming of the adaptive architecture is through a nexus which coordinates reflexive and deliberator components.

  1. Decentralized adaptive control designs and microstrip antennas for smart structures

    NASA Astrophysics Data System (ADS)

    Khorrami, Farshad; Jain, Sandeep; Das, Nirod K.

    1996-05-01

    Smart structures lend themselves naturally to a decentralized control design framework, especially with adaptation mechanisms. The main reason being that it is highly undesirable to connect all the sensors and actuators in a large structure to a central processor. It is rather desirable to have local decision-making at each smart patch. Furthermore, this local controllers should be easily `expandable' to `contractible.' This corresponds to the fact that addition/deletion of several smart patches should not require a total redesign of the control system. The decentralized control strategies advocated in this paper are of expandable/contractible type. On another front, we are considering utilization of micro-strip antennas for power transfer to and from smart structures. We have made preliminary contributions in this direction and further developments are underway. These approaches are being pursued for active vibration damping and noise cancellation via piezoelectric ceramics although the methodology is general enough to be applicable to other type of active structures.

  2. Direct adaptive control of partially known nonlinear systems.

    PubMed

    McLain, R B; Henson, M A; Pottmann, M

    1999-01-01

    A direct adaptive control strategy for a class of single-input/single-output nonlinear systems is presented. The major advantage of the proposed method is that a detailed dynamic nonlinear model is not required for controller design. The only information required about the plant is measurements of the state variables, the relative degree, and the sign of a Lie derivative which appears in the associated input-output linearizing control law. Unknown controller functions are approximated using locally supported radial basis functions that are introduced only in regions of the state space where the closed-loop system actually evolves. Lyapunov stability analysis is used to derive parameter update laws which ensure (under certain assumptions) the state vector remains bounded and the plant output asymptotically tracks the output of a linear reference model. The technique is successfully applied to a nonlinear biochemical reactor model.

  3. Adaptive Control Using Residual Mode Filters Applied to Wind Turbines

    NASA Technical Reports Server (NTRS)

    Frost, Susan A.; Balas, Mark J.

    2011-01-01

    Many dynamic systems containing a large number of modes can benefit from adaptive control techniques, which are well suited to applications that have unknown parameters and poorly known operating conditions. In this paper, we focus on a model reference direct adaptive control approach that has been extended to handle adaptive rejection of persistent disturbances. We extend this adaptive control theory to accommodate problematic modal subsystems of a plant that inhibit the adaptive controller by causing the open-loop plant to be non-minimum phase. We will augment the adaptive controller using a Residual Mode Filter (RMF) to compensate for problematic modal subsystems, thereby allowing the system to satisfy the requirements for the adaptive controller to have guaranteed convergence and bounded gains. We apply these theoretical results to design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed wind turbine that has minimum phase zeros.

  4. The reduced order model problem in distributed parameter systems adaptive identification and control. [adaptive control of flexible spacecraft

    NASA Technical Reports Server (NTRS)

    Johnson, C. R., Jr.; Lawrence, D. A.

    1981-01-01

    The reduced order model problem in distributed parameter systems adaptive identification and control is investigated. A comprehensive examination of real-time centralized adaptive control options for flexible spacecraft is provided.

  5. Adaptive Control of Flexible Structures Using Residual Mode Filters

    NASA Technical Reports Server (NTRS)

    Balas, Mark J.; Frost, Susan

    2010-01-01

    Flexible structures containing a large number of modes can benefit from adaptive control techniques which are well suited to applications that have unknown modeling parameters and poorly known operating conditions. In this paper, we focus on a direct adaptive control approach that has been extended to handle adaptive rejection of persistent disturbances. We extend our adaptive control theory to accommodate troublesome modal subsystems of a plant that might inhibit the adaptive controller. In some cases the plant does not satisfy the requirements of Almost Strict Positive Realness. Instead, there maybe be a modal subsystem that inhibits this property. This section will present new results for our adaptive control theory. We will modify the adaptive controller with a Residual Mode Filter (RMF) to compensate for the troublesome modal subsystem, or the Q modes. Here we present the theory for adaptive controllers modified by RMFs, with attention to the issue of disturbances propagating through the Q modes. We apply the theoretical results to a flexible structure example to illustrate the behavior with and without the residual mode filter. We have proposed a modified adaptive controller with a residual mode filter. The RMF is used to accommodate troublesome modes in the system that might otherwise inhibit the adaptive controller, in particular the ASPR condition. This new theory accounts for leakage of the disturbance term into the Q modes. A simple three-mode example shows that the RMF can restore stability to an otherwise unstable adaptively controlled system. This is done without modifying the adaptive controller design.

  6. National Drug Control Strategy. 2008 Annual Report

    ERIC Educational Resources Information Center

    Office of National Drug Control Policy, 2008

    2008-01-01

    This report presents the 2008 National Drug Control Strategy of the White House Office of National Drug Control Policy. The overarching goal of the President's Strategy is to reduce drug use in America through a balanced approach that focuses on stopping use before it starts, healing America's drug users, and disrupting the market for illegal…

  7. Adaptive collaborative control of highly redundant robots

    NASA Astrophysics Data System (ADS)

    Handelman, David A.

    2008-04-01

    The agility and adaptability of biological systems are worthwhile goals for next-generation unmanned ground vehicles. Management of the requisite number of degrees of freedom, however, remains a challenge, as does the ability of an operator to transfer behavioral intent from human to robot. This paper reviews American Android research funded by NASA, DARPA, and the U.S. Army that attempts to address these issues. Limb coordination technology, an iterative form of inverse kinematics, provides a fundamental ability to control balance and posture independently in highly redundant systems. Goal positions and orientations of distal points of the robot skeleton, such as the hands and feet of a humanoid robot, become variable constraints, as does center-of-gravity position. Behaviors utilize these goals to synthesize full-body motion. Biped walking, crawling and grasping are illustrated, and behavior parameterization, layering and portability are discussed. Robotic skill acquisition enables a show-and-tell approach to behavior modification. Declarative rules built verbally by an operator in the field define nominal task plans, and neural networks trained with verbal, manual and visual signals provide additional behavior shaping. Anticipated benefits of the resultant adaptive collaborative controller for unmanned ground vehicles include increased robot autonomy, reduced operator workload and reduced operator training and skill requirements.

  8. Adaptive vibration control using a virtual-vibration-absorber controller

    NASA Astrophysics Data System (ADS)

    Wu, Shang-Teh; Shao, Ying-Jhe

    2007-09-01

    A control algorithm emulating a dynamic vibration absorber (DVA) is developed for a flexible structure subject to harmonic disturbances of uncertain frequency. The virtual vibration absorber is mathematically equivalent to a passive DVA, but its stiffness, inertia and damping coefficient are adjustable by software. Stiffness of the virtual spring is tuned according to the phase difference between the acceleration of the primary body and the displacement of the virtual mass. The adaptation algorithm consists of a phase detector with a low-pass filter, similar to that found in a phase-locked loop. Both undamped and damped vibration absorbers are developed; the former has the advantage of cleaner vibration neutralization while the latter has a smoother stiffness adaptation. Adaptation rate of the virtual stiffness is analyzed in detail. The effectiveness of the proposed method is confirmed by simulations and real-time experiments.

  9. Wavefront Control for Extreme Adaptive Optics

    SciTech Connect

    Poyneer, L A

    2003-07-16

    Current plans for Extreme Adaptive Optics systems place challenging requirements on wave-front control. This paper focuses on control system dynamics, wave-front sensing and wave-front correction device characteristics. It may be necessary to run an ExAO system after a slower, low-order AO system. Running two independent systems can result in very good temporal performance, provided specific design constraints are followed. The spatially-filtered wave-front sensor, which prevents aliasing and improves PSF sensitivity, is summarized. Different models of continuous and segmented deformable mirrors are studied. In a noise-free case, a piston-tip-tilt segmented MEMS device can achieve nearly equivalent performance to a continuous-sheet DM in compensating for a static phase aberration with use of spatial filtering.

  10. Wavefront control for extreme adaptive optics

    NASA Astrophysics Data System (ADS)

    Poyneer, Lisa A.; Macintosh, Bruce A.

    2003-12-01

    Current plans for Extreme Adaptive Optics systems place challenging requirements on wave-front control. This paper focuses on control system dynamics, wave-front sensing and wave-front correction device characteristics. It may be necessary to run an ExAO system after a slower, low-order AO system. Running two independent systems can result in very good temporal performance, provided specific design constraints are followed. The spatially-filtered wave-front sensor, which prevents aliasing and improves PSF sensitivity, is summarized. Different models of continuous and segmented deformable mirrors are studied. In a noise-free case, a piston-tip-tilt segmented MEMS device can achieve nearly equivalent performance to a continuous-sheet DM in compensating for a static phase aberration with use of spatial filtering.

  11. Exercise-induced stress response as an adaptive tolerance strategy.

    PubMed Central

    Sonneborn, J S; Barbee, S A

    1998-01-01

    Interaction between the quality of the environment and the health of the exposed population determines the survival response of living organisms. The phenomenon of induced tolerance by exposure to threshold levels of stressors to stimulate natural defense mechanisms has potential therapeutic value. The paucity of information on predictability of individual response and information on the operative fundamental mechanisms limit applicability of the adaptive tolerance strategy. A potential biomarker of the stress response includes members of the stress-inducible ubiquitin gene family. Transcript sizes detected with Northern blot analysis identify different classes of ubiquitin gene family members and the intensity of the radioactive signal allows abundance determinations. Using moderate exercise as the stressor, significant increase (p < 0.028) in abundance of inducible polyubiquitin genes was found in human blood. Both the potential of exercise as a model system of a natural stress inducer and polyubiquitin as a biomarker of stress were established in these studies. Images Figure 1 Figure 2 PMID:9539026

  12. Real-time Adaptive Control Using Neural Generalized Predictive Control

    NASA Technical Reports Server (NTRS)

    Haley, Pam; Soloway, Don; Gold, Brian

    1999-01-01

    The objective of this paper is to demonstrate the feasibility of a Nonlinear Generalized Predictive Control algorithm by showing real-time adaptive control on a plant with relatively fast time-constants. Generalized Predictive Control has classically been used in process control where linear control laws were formulated for plants with relatively slow time-constants. The plant of interest for this paper is a magnetic levitation device that is nonlinear and open-loop unstable. In this application, the reference model of the plant is a neural network that has an embedded nominal linear model in the network weights. The control based on the linear model provides initial stability at the beginning of network training. In using a neural network the control laws are nonlinear and online adaptation of the model is possible to capture unmodeled or time-varying dynamics. Newton-Raphson is the minimization algorithm. Newton-Raphson requires the calculation of the Hessian, but even with this computational expense the low iteration rate make this a viable algorithm for real-time control.

  13. Optimal control of anthracnose using mixed strategies.

    PubMed

    Fotsa Mbogne, David Jaures; Thron, Christopher

    2015-11-01

    In this paper we propose and study a spatial diffusion model for the control of anthracnose disease in a bounded domain. The model is a generalization of the one previously developed in [15]. We use the model to simulate two different types of control strategies against anthracnose disease. Strategies that employ chemical fungicides are modeled using a continuous control function; while strategies that rely on cultivational practices (such as pruning and removal of mummified fruits) are modeled with a control function which is discrete in time (though not in space). For comparative purposes, we perform our analyses for a spatially-averaged model as well as the space-dependent diffusion model. Under weak smoothness conditions on parameters we demonstrate the well-posedness of both models by verifying existence and uniqueness of the solution for the growth inhibition rate for given initial conditions. We also show that the set [0, 1] is positively invariant. We first study control by impulsive strategies, then analyze the simultaneous use of mixed continuous and pulse strategies. In each case we specify a cost functional to be minimized, and we demonstrate the existence of optimal control strategies. In the case of pulse-only strategies, we provide explicit algorithms for finding the optimal control strategies for both the spatially-averaged model and the space-dependent model. We verify the algorithms for both models via simulation, and discuss properties of the optimal solutions.

  14. An Adaptive, Receding-Horizon Guidance Strategy for Solar Sail Trajectories

    NASA Astrophysics Data System (ADS)

    Wawrzyniak, Geoffrey G.; Howell, Kathleen C.

    2012-12-01

    Without additional attitude and orbital control systems, such as thrusters, solar-sail trajectories are controlled by the orientation of the sailcraft. The sail attitude is employed to target the sailcraft to some future state along the reference trajectory. In a "turn-and-hold" strategy, the attitude profile consists of at least three orientations between an initial and future, target state along the trajectory. Because of orbit-knowledge, control, and turn-modeling errors, a look-ahead control strategy is generated, one in which only the first turn from the profile is performed, and then a new profile is constructed based on updated orbit knowledge. The initial hold intervals, along with the number of turns, used to generate an attitude profile is automatically adapted to improve convergence of the algorithm. This technique is generally successful when applied to reference trajectories generated in an Earth-Moon-Sun ephemeris regime.

  15. Adaptive Torque Control of Variable Speed Wind Turbines

    SciTech Connect

    Johnson, K. E.

    2004-08-01

    The primary focus of this work is a new adaptive controller that is designed to resemble the standard non-adaptive controller used by the wind industry for variable speed wind turbines below rated power. This adaptive controller uses a simple, highly intuitive gain adaptation law designed to seek out the optimal gain for maximizing the turbine's energy capture. It is designed to work even in real, time-varying winds.

  16. Robust adaptive neural network control of uncertain nonholonomic systems with strong nonlinear drifts.

    PubMed

    Wang, Z P; Ge, S S; Lee, T H

    2004-10-01

    In this paper, robust adaptive neural network (NN) control is presented to solve the control problem of nonholonomic systems in chained form with unknown virtual control coefficients and strong drift nonlinearities. The robust adaptive NN control laws are developed using state scaling and backstepping. Uniform ultimate boundedness of all the signals in the closed-loop are guaranteed, and the system states are proven to converge to a small neighborhood of zero. The control performance of the closed-loop system is guaranteed by appropriately choosing the design parameters. The proposed adaptive NN control is free of control singularity problem. An adaptive control based switching strategy is used to overcome the uncontrollability problem associated with x0 (t0) = 0. The simulation results demonstrate the effectiveness of the proposed controllers.

  17. Adaptive strategies in designing the simultaneous global drug development program.

    PubMed

    Yuan, Zhilong; Chen, Gang; Huang, Qin

    2016-01-01

    Many methods have been proposed to account for the potential impact of ethnic/regional factors when extrapolating results from multiregional clinical trials (MRCTs) to targeted ethnic (TE) patients, i.e., "bridging." Most of them either focused on TE patients in the MRCT (i.e., internal bridging) or a separate local clinical trial (LCT) (i.e., external bridging). Huang et al. (2012) integrated both bridging concepts in their method for the Simultaneous Global Drug Development Program (SGDDP) which designs both the MRCT and the LCT prospectively and combines patients in both trials by ethnic origin, i.e., TE vs. non-TE (NTE). The weighted Z test was used to combine information from TE and NTE patients to test with statistical rigor whether a new treatment is effective in the TE population. Practically, the MRCT is often completed before the LCT. Thus to increase the power for the SGDDP and/or obtain more informative data in TE patients, we may use the final results from the MRCT to re-evaluate initial assumptions (e.g., effect sizes, variances, weight), and modify the LCT accordingly. We discuss various adaptive strategies for the LCT such as sample size reassessment, population enrichment, endpoint change, and dose adjustment. As an example, we extend a popular adaptive design method to re-estimate the sample size for the LCT, and illustrate it for a normally distributed endpoint.

  18. Stress Response and Perinatal Reprogramming: Unraveling (Mal)adaptive Strategies

    PubMed Central

    Musazzi, Laura; Marrocco, Jordan

    2016-01-01

    Environmental stressors induce coping strategies in the majority of individuals. The stress response, involving the activation of the hypothalamic-pituitary-adrenocortical axis and the consequent release of corticosteroid hormones, is indeed aimed at promoting metabolic, functional, and behavioral adaptations. However, behavioral stress is also associated with fast and long-lasting neurochemical, structural, and behavioral changes, leading to long-term remodeling of glutamate transmission, and increased susceptibility to neuropsychiatric disorders. Of note, early-life events, both in utero and during the early postnatal life, trigger reprogramming of the stress response, which is often associated with loss of stress resilience and ensuing neurobehavioral (mal)adaptations. Indeed, adverse experiences in early life are known to induce long-term stress-related neuropsychiatric disorders in vulnerable individuals. Here, we discuss recent findings about stress remodeling of excitatory neurotransmission and brain morphology in animal models of behavioral stress. These changes are likely driven by epigenetic factors that lie at the core of the stress-response reprogramming in individuals with a history of perinatal stress. We propose that reprogramming mechanisms may underlie the reorganization of excitatory neurotransmission in the short- and long-term response to stressful stimuli. PMID:27057367

  19. Mean deviation coupling synchronous control for multiple motors via second-order adaptive sliding mode control.

    PubMed

    Li, Lebao; Sun, Lingling; Zhang, Shengzhou

    2016-05-01

    A new mean deviation coupling synchronization control strategy is developed for multiple motor control systems, which can guarantee the synchronization performance of multiple motor control systems and reduce complexity of the control structure with the increasing number of motors. The mean deviation coupling synchronization control architecture combining second-order adaptive sliding mode control (SOASMC) approach is proposed, which can improve synchronization control precision of multiple motor control systems and make speed tracking errors, mean speed errors of each motor and speed synchronization errors converge to zero rapidly. The proposed control scheme is robustness to parameter variations and random external disturbances and can alleviate the chattering phenomena. Moreover, an adaptive law is employed to estimate the unknown bound of uncertainty, which is obtained in the sense of Lyapunov stability theorem to minimize the control effort. Performance comparisons with master-slave control, relative coupling control, ring coupling control, conventional PI control and SMC are investigated on a four-motor synchronization control system. Extensive comparative results are given to shown the good performance of the proposed control scheme.

  20. Mesh refinement strategy for optimal control problems

    NASA Astrophysics Data System (ADS)

    Paiva, L. T.; Fontes, F. A. C. C.

    2013-10-01

    Direct methods are becoming the most used technique to solve nonlinear optimal control problems. Regular time meshes having equidistant spacing are frequently used. However, in some cases these meshes cannot cope accurately with nonlinear behavior. One way to improve the solution is to select a new mesh with a greater number of nodes. Another way, involves adaptive mesh refinement. In this case, the mesh nodes have non equidistant spacing which allow a non uniform nodes collocation. In the method presented in this paper, a time mesh refinement strategy based on the local error is developed. After computing a solution in a coarse mesh, the local error is evaluated, which gives information about the subintervals of time domain where refinement is needed. This procedure is repeated until the local error reaches a user-specified threshold. The technique is applied to solve the car-like vehicle problem aiming minimum consumption. The approach developed in this paper leads to results with greater accuracy and yet with lower overall computational time as compared to using a time meshes having equidistant spacing.

  1. A forward method for optimal stochastic nonlinear and adaptive control

    NASA Technical Reports Server (NTRS)

    Bayard, David S.

    1988-01-01

    A computational approach is taken to solve the optimal nonlinear stochastic control problem. The approach is to systematically solve the stochastic dynamic programming equations forward in time, using a nested stochastic approximation technique. Although computationally intensive, this provides a straightforward numerical solution for this class of problems and provides an alternative to the usual dimensionality problem associated with solving the dynamic programming equations backward in time. It is shown that the cost degrades monotonically as the complexity of the algorithm is reduced. This provides a strategy for suboptimal control with clear performance/computation tradeoffs. A numerical study focusing on a generic optimal stochastic adaptive control example is included to demonstrate the feasibility of the method.

  2. FPGA-accelerated adaptive optics wavefront control

    NASA Astrophysics Data System (ADS)

    Mauch, S.; Reger, J.; Reinlein, C.; Appelfelder, M.; Goy, M.; Beckert, E.; Tünnermann, A.

    2014-03-01

    The speed of real-time adaptive optical systems is primarily restricted by the data processing hardware and computational aspects. Furthermore, the application of mirror layouts with increasing numbers of actuators reduces the bandwidth (speed) of the system and, thus, the number of applicable control algorithms. This burden turns out a key-impediment for deformable mirrors with continuous mirror surface and highly coupled actuator influence functions. In this regard, specialized hardware is necessary for high performance real-time control applications. Our approach to overcome this challenge is an adaptive optics system based on a Shack-Hartmann wavefront sensor (SHWFS) with a CameraLink interface. The data processing is based on a high performance Intel Core i7 Quadcore hard real-time Linux system. Employing a Xilinx Kintex-7 FPGA, an own developed PCie card is outlined in order to accelerate the analysis of a Shack-Hartmann Wavefront Sensor. A recently developed real-time capable spot detection algorithm evaluates the wavefront. The main features of the presented system are the reduction of latency and the acceleration of computation For example, matrix multiplications which in general are of complexity O(n3 are accelerated by using the DSP48 slices of the field-programmable gate array (FPGA) as well as a novel hardware implementation of the SHWFS algorithm. Further benefits are the Streaming SIMD Extensions (SSE) which intensively use the parallelization capability of the processor for further reducing the latency and increasing the bandwidth of the closed-loop. Due to this approach, up to 64 actuators of a deformable mirror can be handled and controlled without noticeable restriction from computational burdens.

  3. Adaptive powertrain control for plugin hybrid electric vehicles

    DOEpatents

    Kedar-Dongarkar, Gurunath; Weslati, Feisel

    2013-10-15

    A powertrain control system for a plugin hybrid electric vehicle. The system comprises an adaptive charge sustaining controller; at least one internal data source connected to the adaptive charge sustaining controller; and a memory connected to the adaptive charge sustaining controller for storing data generated by the at least one internal data source. The adaptive charge sustaining controller is operable to select an operating mode of the vehicle's powertrain along a given route based on programming generated from data stored in the memory associated with that route. Further described is a method of adaptively controlling operation of a plugin hybrid electric vehicle powertrain comprising identifying a route being traveled, activating stored adaptive charge sustaining mode programming for the identified route and controlling operation of the powertrain along the identified route by selecting from a plurality of operational modes based on the stored adaptive charge sustaining mode programming.

  4. Driver behaviour with adaptive cruise control.

    PubMed

    Stanton, Neville A; Young, Mark S

    2005-08-15

    This paper reports on the evaluation of adaptive cruise control (ACC) from a psychological perspective. It was anticipated that ACC would have an effect upon the psychology of driving, i.e. make the driver feel like they have less control, reduce the level of trust in the vehicle, make drivers less situationally aware, but workload might be reduced and driving might be less stressful. Drivers were asked to drive in a driving simulator under manual and ACC conditions. Analysis of variance techniques were used to determine the effects of workload (i.e. amount of traffic) and feedback (i.e. degree of information from the ACC system) on the psychological variables measured (i.e. locus of control, trust, workload, stress, mental models and situation awareness). The results showed that: locus of control and trust were unaffected by ACC, whereas situation awareness, workload and stress were reduced by ACC. Ways of improving situation awareness could include cues to help the driver predict vehicle trajectory and identify conflicts.

  5. Sensor Web Dynamic Measurement Techniques and Adaptive Observing Strategies

    NASA Technical Reports Server (NTRS)

    Talabac, Stephen J.

    2004-01-01

    Sensor Web observing systems may have the potential to significantly improve our ability to monitor, understand, and predict the evolution of rapidly evolving, transient, or variable environmental features and events. This improvement will come about by integrating novel data collection techniques, new or improved instruments, emerging communications technologies and protocols, sensor mark-up languages, and interoperable planning and scheduling systems. In contrast to today's observing systems, "event-driven" sensor webs will synthesize real- or near-real time measurements and information from other platforms and then react by reconfiguring the platforms and instruments to invoke new measurement modes and adaptive observation strategies. Similarly, "model-driven" sensor webs will utilize environmental prediction models to initiate targeted sensor measurements or to use a new observing strategy. The sensor web concept contrasts with today's data collection techniques and observing system operations concepts where independent measurements are made by remote sensing and in situ platforms that do not share, and therefore cannot act upon, potentially useful complementary sensor measurement data and platform state information. This presentation describes NASA's view of event-driven and model-driven Sensor Webs and highlights several research and development activities at the Goddard Space Flight Center.

  6. Suppressing traffic-driven epidemic spreading by adaptive routing strategy

    NASA Astrophysics Data System (ADS)

    Yang, Han-Xin; Wang, Zhen

    2016-12-01

    Despite extensive work on the interplay between traffic dynamics and epidemic spreading, the control of epidemic spreading by routing strategies has not received adequate attention. In this paper, we study the impact of efficient routing protocol on epidemic spreading. In the case of infinite node-delivery capacity, where the traffic is free of congestion, we find that that there exists optimal values of routing parameter, leading to the maximal epidemic threshold. This means that epidemic spreading can be effectively controlled by fine tuning the routing scheme. Moreover, we find that an increase in the average network connectivity and the emergence of traffic congestion can suppress the epidemic outbreak.

  7. Comparison of adaptive algorithms for the control of tonal disturbances in mechanical systems

    NASA Astrophysics Data System (ADS)

    Zilletti, M.; Elliott, S. J.; Cheer, J.

    2016-09-01

    This paper presents a study on the performance of adaptive control algorithms designed to reduce the vibration of mechanical systems excited by a harmonic disturbance. The mechanical system consists of a mass suspended on a spring and a damper. The system is equipped with a force actuator in parallel with the suspension. The control signal driving the actuator is generated by adjusting the amplitude and phase of a sinusoidal reference signal at the same frequency as the excitation. An adaptive feedforward control algorithm is used to adapt the amplitude and phase of the control signal, to minimise the mean square velocity of the mass. Two adaptation strategies are considered in which the control signal is either updated after each period of the oscillation or at every time sample. The first strategy is traditionally used in vibration control in helicopters for example; the second strategy is normally referred to as the filtered-x least mean square algorithm and is often used to control engine noise in cars. The two adaptation strategies are compared through a parametric study, which investigates the influence of the properties of both the mechanical system and the control system on the convergence speed of the two algorithms.

  8. Adaptive fractionation therapy: I. Basic concept and strategy

    NASA Astrophysics Data System (ADS)

    Lu, Weiguo; Chen, Mingli; Chen, Quan; Ruchala, Kenneth; Olivera, Gustavo

    2008-10-01

    Radiotherapy is fractionized to increase the therapeutic ratio. Fractionation in conventional treatment is determined as part of the prescription, and a fixed fraction size is used for the whole course of treatment. Due to patients' day-to-day variations on the relative distance between the tumor and the organs at risk (OAR), a better therapeutic ratio may be attained by using an adaptive fraction size. Intuitively, we want to use a larger fraction size when OAR and the tumor are far apart and a smaller fraction size when OAR and the tumor are close to each other. The concept and strategies of adaptive fractionation therapy (AFT) are introduced in this paper. AFT is an on-line adaptive technique that utilizes the variations of internal structures to get optimal OAR sparing. Changes of internal structures are classified as different configurations according to their feasibility to the radiation delivery. A priori knowledge is used to describe the probability distribution of these configurations. On-line processes include identifying the configuration via daily image guidance and optimizing the current fraction size. The optimization is modeled as a dynamic linear programming problem so that at the end of the treatment course, the tumor receives the same planned dose while OAR receives less dose than the regular fractionation delivery. Extensive simulations, which include thousands of treatment courses with each course consisting of 40 fractions, are used to test the efficiency and robustness of the presented technique. The gains of OAR sparing depend on the variations on configurations and the bounds of the fraction size. The larger the variations and the looser the bounds are, the larger the gains will be. Compared to the conventional fractionation technique with 2 Gy/fraction in 40 fractions, for a 20% variation on tumor-OAR configurations and [1 Gy, 3 Gy] fraction size bounds, the cumulative OAR dose with adaptive fractionation is 3-8 Gy, or 7-20% less than that

  9. Control Strategies for School Boards.

    ERIC Educational Resources Information Center

    Knoop, Robert

    1987-01-01

    Presents a model that administrators can use to control the teaching-learning process. Definitions are provided for the model's six elements: budgeting, reports, policies, organizational structures, professionalism, and staff selection and training. Notes that involvement of teachers and students in the control process minimizes communication…

  10. Stochastic Adaptive Control and Estimation Enhancement

    DTIC Science & Technology

    1989-09-01

    total Zu(N-J)’Gj’Q(N)FxIN-1)ou (N-I)I’[ R (N- 1) ’(N I Gil probability theorem to (4.3) yields J*(k.k 3 - min ( Ejx(kl 0(k)x(k) - u(k)’R(klu(k) trQ(N)VI m...Is Independent of Mil), I-k*2 .... N If Dec. 1988. [ Gil N.H. Gholson and R.L. Moose, "ManeuveringM(k.1J Is known, thus Target Tracking Using Adaptive...Control and A(t) =_ J1N X(i,t) is uniformly bounded. Quasi-Variational Inequalities, Gauthier- Villars , . (t9. tER4 , exits 0’ at most a countable

  11. Two-DOF precision platform for spacecraft thrust vector control: control strategies and simulations

    NASA Astrophysics Data System (ADS)

    Ma, Kougen; Ghasemi-Nejhad, Mehrdad N.

    2004-07-01

    This paper presents control strategies and simulations of a two-DOF precision platform as an adaptive thruster mount structure with precision positioning and active vibration suppression capabilities for thrust vector control of space satellites. First, the configuration of the two-DOF precision platform is introduced, which is an intelligent tripod with two in-plane rotational degrees of freedom for the top device-plate. Precision positioning of this platform is achieved using active members that extend or contract to tilt the top device-plate where the thruster is mounted. Kinematic analysis of the platform is then presented and followed by two control strategies; namely local control strategy and global control strategy. In the local control strategy, the motion of each active member is controlled locally according to the kinematical feature of the platform and the local sensor information to achieve the desired tilt of the top device-plate. In the global control strategy, the motion of each active member is adjusted according to the system level information from a tilt sensor. Fuzzy logic control is employed and the two control strategies are simulated and compared.

  12. Stable adaptive control using new critic designs

    NASA Astrophysics Data System (ADS)

    Werbos, Paul J.

    1999-03-01

    Classical adaptive control proves total-system stability for control of linear plants, but only for plants meeting very restrictive assumptions. Approximate Dynamic Programming (ADP) has the potential, in principle, to ensure stability without such tight restrictions. It also offers nonlinear and neural extensions for optimal control, with empirically supported links to what is seen in the brain. However, the relevant ADP methods in use today--TD, HDP, DHP, GDHP--and the Galerkin-based versions of these all have serious limitations when used here as parallel distributed real-time learning systems; either they do not possess quadratic unconditional stability (to be defined) or they lead to incorrect results in the stochastic case. (ADAC or Q- learning designs do not help.) After explaining these conclusions, this paper describes new ADP designs which overcome these limitations. It also addresses the Generalized Moving Target problem, a common family of static optimization problems, and describes a way to stabilize large-scale economic equilibrium models, such as the old long-term energy mode of DOE.

  13. 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.

  14. Full-Scale Flight Research Testbeds: Adaptive and Intelligent Control

    NASA Technical Reports Server (NTRS)

    Pahle, Joe W.

    2008-01-01

    This viewgraph presentation describes the adaptive and intelligent control methods used for aircraft survival. The contents include: 1) Motivation for Adaptive Control; 2) Integrated Resilient Aircraft Control Project; 3) Full-scale Flight Assets in Use for IRAC; 4) NASA NF-15B Tail Number 837; 5) Gen II Direct Adaptive Control Architecture; 6) Limited Authority System; and 7) 837 Flight Experiments. A simulated destabilization failure analysis along with experience and lessons learned are also presented.

  15. A survey of adaptive control technology in robotics

    NASA Technical Reports Server (NTRS)

    Tosunoglu, S.; Tesar, D.

    1987-01-01

    Previous work on the adaptive control of robotic systems is reviewed. Although the field is relatively new and does not yet represent a mature discipline, considerable attention has been given to the design of sophisticated robot controllers. Here, adaptive control methods are divided into model reference adaptive systems and self-tuning regulators with further definition of various approaches given in each class. The similarity and distinct features of the designed controllers are delineated and tabulated to enhance comparative review.

  16. Adaptive and qualitative changes in encoding strategy with experience: evidence from the test-expectancy paradigm.

    PubMed

    Finley, Jason R; Benjamin, Aaron S

    2012-05-01

    Three experiments demonstrated learners' abilities to adaptively and qualitatively accommodate their encoding strategies to the demands of an upcoming test. Stimuli were word pairs. In Experiment 1, test expectancy was induced for either cued recall (of targets given cues) or free recall (of targets only) across 4 study-test cycles of the same test format, followed by a final critical cycle featuring either the expected or the unexpected test format. For final tests of both cued and free recall, participants who had expected that test format outperformed those who had not. This disordinal interaction, supported by recognition and self-report data, demonstrated not mere differences in effort based on anticipated test difficulty, but rather qualitative and appropriate differences in encoding strategies based on expected task demands. Participants also came to appropriately modulate metacognitive monitoring (Experiment 2) and study-time allocation (Experiment 3) across study-test cycles. Item and associative recognition performance, as well as self-report data, revealed shifts in encoding strategies across trials; these results were used to characterize and evaluate the different strategies that participants employed for cued versus free recall and to assess the optimality of participants' metacognitive control of encoding strategies. Taken together, these data illustrate a sophisticated form of metacognitive control, in which learners qualitatively shift encoding strategies to match the demands of anticipated tests.

  17. Adaptive and Qualitative Changes in Encoding Strategy With Experience: Evidence From the Test-Expectancy Paradigm

    PubMed Central

    Finley, Jason R.; Benjamin, Aaron S.

    2012-01-01

    Three experiments demonstrated learners’ abilities to adaptively and qualitatively accommodate their encoding strategies to the demands of an upcoming test. Stimuli were word pairs. In Experiment 1, test expectancy was induced for either cued recall (of targets given cues) or free recall (of targets only) across 4 study–test cycles of the same test format, followed by a final critical cycle featuring either the expected or the unexpected test format. For final tests of both cued and free recall, participants who had expected that test format outperformed those who had not. This disordinal interaction, supported by recognition and self-report data, demonstrated not mere differences in effort based on anticipated test difficulty, but rather qualitative and appropriate differences in encoding strategies based on expected task demands. Participants also came to appropriately modulate metacognitive monitoring (Experiment 2) and study-time allocation (Experiment 3) across study–test cycles. Item and associative recognition performance, as well as self-report data, revealed shifts in encoding strategies across trials; these results were used to characterize and evaluate the different strategies that participants employed for cued versus free recall and to assess the optimality of participants’ metacognitive control of encoding strategies. Taken together, these data illustrate a sophisticated form of metacognitive control, in which learners qualitatively shift encoding strategies to match the demands of anticipated tests. PMID:22103783

  18. Control architecture for an adaptive electronically steerable flash lidar and associated instruments

    NASA Astrophysics Data System (ADS)

    Ruppert, Lyle; Craner, Jeremy; Harris, Timothy

    2014-09-01

    An Electronically Steerable Flash Lidar (ESFL), developed by Ball Aerospace & Technologies Corporation, allows realtime adaptive control of configuration and data-collection strategy based on recent or concurrent observations and changing situations. This paper reviews, at a high level, some of the algorithms and control architecture built into ESFL. Using ESFL as an example, it also discusses the merits and utility such adaptable instruments in Earth-system studies.

  19. Classical and adaptive control algorithms for the solar array pointing system of the Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Ianculescu, G. D.; Klop, J. J.

    1992-01-01

    Classical and adaptive control algorithms for the solar array pointing system of the Space Station Freedom are designed using a continuous rigid body model of the solar array gimbal assembly containing both linear and nonlinear dynamics due to various friction components. The robustness of the design solution is examined by performing a series of sensitivity analysis studies. Adaptive control strategies are examined in order to compensate for the unfavorable effect of static nonlinearities, such as dead-zone uncertainties.

  20. Adaptive Feed-Forward Control of a Turbulent Boundary Layer

    NASA Astrophysics Data System (ADS)

    Breuer, K. S.; Rathnasingham, R.

    1997-11-01

    Recent progress in the active control of a turbulent boundary is reported. A matrix of three shear sensors and three actuators are used to control the fluctuation statistics at three ``control points'' downstream of the actuators. Althouh any measureable quantity can be controlled, the present results are only for (i) streamwise velocity fluctuations at y^+ = 15 and (ii) wall-pressure fluctuations. The control algorithm used is an adaptive feed-forward scheme in which the signal at each control point is estimated using a linear multiple-input multiple-output (MIMO) predictive filter with pre-conditioning to isolate the large-scale structures associated with turbulence production. The actuator inputs are then designed to linearly cancel the predicted signals. Results are presented showing excellent performance of the forward prediction and a broad reduction in the rms of the control variables which extends uniformly behind the control patch. Different optimization strategies, nonlinear corrections and sensor pre-conditioning methods are also discussed.

  1. Ethnic enclaves and middleman minorities: alternative strategies of immigrant adaptation?

    PubMed

    Cobas, J A

    1987-04-01

    This article examines 2 modes or strategies of immigrant adaptation: middleman minorities and ethnic enclaves. Although they have been discussed as if they were disjointed and mutually exclusive, the authors challenge this view. Middleman minorities 1) tend to be self-employed or to work for a coethnic, 2) are usually concentrated in small business, 3) tend to rely on the in-group for resources, and 4) fill a "status gap" in the receiving society. Ethnic enclaves depend on 3 features: 1) recent coethnic arrivals spend a tour of duty at the worst jobs, 2) coethnics provide ethnic entrepreneurs with consumer markets, 3) ethnic businesses rely on each other to supply their operating needs. Ethnic enclaves are concentrated and spatially identifiable. For this study, the authors collected data in a survey of the Cuban exile community of San Juan, Puerto Rico. The sample selection procedure yielded a total of 261 individuals, 220 of whom were interviewed. 10 predictions found in the middleman minority and ethnic enclave perspectives were checked against the researchers' data. 4 of these predictions are hld in common by both approaches: 1) eomployment in an ethnic enterprise increases subsequent chances of self-employment, 2) ethnic firms rely on the in-group for business resources, 3) coethnic workers represent an asset to the ethnic entrepreneur in that they occupy important positions requiring the employer's trust, and 4) there is business competition between locals and minority members. As predicted by the middleman strategy, Cuban businesses in Puerto Rico tend not to be immediately productive and there is no evidence of spatial concentration of these businesses. However, fitting the enclave approach, these firms do not dominate certain business lines, Cuban entrepreneurs do not appear to be sojourners, and they tend to have business backgrounds. The middleman perspective is supported in that some elements of the local elite favor Cuban exiles. Thus, there is no

  2. Adaptive Control Allocation in the Presence of Actuator Failures

    NASA Technical Reports Server (NTRS)

    Liu, Yu; Crespo, Luis G.

    2010-01-01

    In this paper, a novel adaptive control allocation framework is proposed. In the adaptive control allocation structure, cooperative actuators are grouped and treated as an equivalent control effector. A state feedback adaptive control signal is designed for the equivalent effector and allocated to the member actuators adaptively. Two adaptive control allocation algorithms are proposed, which guarantee closed-loop stability and asymptotic state tracking in the presence of uncertain loss of effectiveness and constant-magnitude actuator failures. The proposed algorithms can be shown to reduce the controller complexity with proper grouping of the actuators. The proposed adaptive control allocation schemes are applied to two linearized aircraft models, and the simulation results demonstrate the performance of the proposed algorithms.

  3. Invasion strategies in clonal aquatic plants: are phenotypic differences caused by phenotypic plasticity or local adaptation?

    PubMed

    Riis, Tenna; Lambertini, Carla; Olesen, Birgit; Clayton, John S; Brix, Hans; Sorrell, Brian K

    2010-11-01

    The successful spread of invasive plants in new environments is often linked to multiple introductions and a diverse gene pool that facilitates local adaptation to variable environmental conditions. For clonal plants, however, phenotypic plasticity may be equally important. Here the primary adaptive strategy in three non-native, clonally reproducing macrophytes (Egeria densa, Elodea canadensis and Lagarosiphon major) in New Zealand freshwaters were examined and an attempt was made to link observed differences in plant morphology to local variation in habitat conditions. Field populations with a large phenotypic variety were sampled in a range of lakes and streams with different chemical and physical properties. The phenotypic plasticity of the species before and after cultivation was studied in a common garden growth experiment, and the genetic diversity of these same populations was also quantified. For all three species, greater variation in plant characteristics was found before they were grown in standardized conditions. Moreover, field populations displayed remarkably little genetic variation and there was little interaction between habitat conditions and plant morphological characteristics. The results indicate that at the current stage of spread into New Zealand, the primary adaptive strategy of these three invasive macrophytes is phenotypic plasticity. However, while limited, the possibility that genetic diversity between populations may facilitate ecotypic differentiation in the future cannot be excluded. These results thus indicate that invasive clonal aquatic plants adapt to new introduced areas by phenotypic plasticity. Inorganic carbon, nitrogen and phosphorous were important in controlling plant size of E. canadensis and L. major, but no other relationships between plant characteristics and habitat conditions were apparent. This implies that within-species differences in plant size can be explained by local nutrient conditions. All together this

  4. Invasion strategies in clonal aquatic plants: are phenotypic differences caused by phenotypic plasticity or local adaptation?

    PubMed Central

    Riis, Tenna; Lambertini, Carla; Olesen, Birgit; Clayton, John S.; Brix, Hans; Sorrell, Brian K.

    2010-01-01

    Background and Aims The successful spread of invasive plants in new environments is often linked to multiple introductions and a diverse gene pool that facilitates local adaptation to variable environmental conditions. For clonal plants, however, phenotypic plasticity may be equally important. Here the primary adaptive strategy in three non-native, clonally reproducing macrophytes (Egeria densa, Elodea canadensis and Lagarosiphon major) in New Zealand freshwaters were examined and an attempt was made to link observed differences in plant morphology to local variation in habitat conditions. Methods Field populations with a large phenotypic variety were sampled in a range of lakes and streams with different chemical and physical properties. The phenotypic plasticity of the species before and after cultivation was studied in a common garden growth experiment, and the genetic diversity of these same populations was also quantified. Key Results For all three species, greater variation in plant characteristics was found before they were grown in standardized conditions. Moreover, field populations displayed remarkably little genetic variation and there was little interaction between habitat conditions and plant morphological characteristics. Conclusions The results indicate that at the current stage of spread into New Zealand, the primary adaptive strategy of these three invasive macrophytes is phenotypic plasticity. However, while limited, the possibility that genetic diversity between populations may facilitate ecotypic differentiation in the future cannot be excluded. These results thus indicate that invasive clonal aquatic plants adapt to new introduced areas by phenotypic plasticity. Inorganic carbon, nitrogen and phosphorous were important in controlling plant size of E. canadensis and L. major, but no other relationships between plant characteristics and habitat conditions were apparent. This implies that within-species differences in plant size can be explained

  5. Progress in adaptive control of flexible spacecraft using lattice filters

    NASA Technical Reports Server (NTRS)

    Sundararajan, N.; Montgomery, R. C.

    1985-01-01

    This paper reviews the use of the least square lattice filter in adaptive control systems. Lattice filters have been used primarily in speech and signal processing, but they have utility in adaptive control because of their order-recursive nature. They are especially useful in dealing with structural dynamics systems wherein the order of a controller required to damp a vibration is variable depending on the number of modes significantly excited. Applications are presented for adaptive control of a flexible beam. Also, difficulties in the practical implementation of the lattice filter in adaptive control are discussed.

  6. Adaptive Gaze Strategies for Locomotion with Constricted Visual Field

    PubMed Central

    Authié, Colas N.; Berthoz, Alain; Sahel, José-Alain; Safran, Avinoam B.

    2017-01-01

    In retinitis pigmentosa (RP), loss of peripheral visual field accounts for most difficulties encountered in visuo-motor coordination during locomotion. The purpose of this study was to accurately assess the impact of peripheral visual field loss on gaze strategies during locomotion, and identify compensatory mechanisms. Nine RP subjects presenting a central visual field limited to 10–25° in diameter, and nine healthy subjects were asked to walk in one of three directions—straight ahead to a visual target, leftward and rightward through a door frame, with or without obstacle on the way. Whole body kinematics were recorded by motion capture, and gaze direction in space was reconstructed using an eye-tracker. Changes in gaze strategies were identified in RP subjects, including extensive exploration prior to walking, frequent fixations of the ground (even knowing no obstacle was present), of door edges, essentially of the proximal one, of obstacle edge/corner, and alternating door edges fixations when approaching the door. This was associated with more frequent, sometimes larger rapid-eye-movements, larger movements, and forward tilting of the head. Despite the visual handicap, the trajectory geometry was identical between groups, with a small decrease in walking speed in RPs. These findings identify the adaptive changes in sensory-motor coordination, in order to ensure visual awareness of the surrounding, detect changes in spatial configuration, collect information for self-motion, update the postural reference frame, and update egocentric distances to environmental objects. They are of crucial importance for the design of optimized rehabilitation procedures. PMID:28798674

  7. Photosynthetic adaptation strategy of Ulva prolifera floating on the sea surface to environmental changes.

    PubMed

    Zhao, Xinyu; Tang, Xuexi; Zhang, Huanxin; Qu, Tongfei; Wang, Ying

    2016-10-01

    For 8 consecutive years, a green tide has originated in the southern Yellow Sea and spread to the Qingdao offshore area. The causative species, Ulva prolifera, always forms a very thick thallus mat that is capable of drifting long distances over long periods. During this process, although the thalli face disturbance by complex environmental factors, they maintain high biomass and proliferation. We hypothesized that some form of photosynthetic adaptation strategy must exist to protect the thalli. Therefore, we studied the different photosynthetic response characteristics of the surface and lower layers of the floating thallus mats, and investigated the physiological and molecular-level adaptation mechanisms. The results showed that: (1) U. prolifera has strong photosynthetic capability that ensures it can gain sufficient energy to increase its biomass and adapt to long-distance migration. (2) Surface layer thalli adapt to the complex environment by dissipating excess energy via photosynthetic quantum control (energy quenching and energy redistribution between PSII/PSI) to avoid irreversible damage to the photosynthetic system. (3) Lower layer thalli increase their contents of Chlorophyll a (Chl a) and Chlorophyll b (Chl b) and decrease their Chl a/Chl b ratio to improve their ability to use light energy. (4) U. prolifera has strong photosynthetic plasticity and can adapt to frequent exchange between the surface and lower layer environments because of wave disturbance. Pigment component changes, energy quenching, and energy redistribution between PSII/PSI contribute to this photosynthetic plasticity.

  8. Analysis and simulation of aperture-sizing strategies with partial adaptive optics

    NASA Astrophysics Data System (ADS)

    Tyson, Robert K.

    1994-05-01

    The central core intensity of a stellar image observed by a ground-based telescope can be maximized by a judicious balancing of the adaptive optics system and the size of the telescope entrance aperture. For a given aperture, increasing the number of degrees of adaptive optics turbulence compensation will maximize the brightness of the central core. However, for an observatory using an adaptive optics system with a fixed number of degrees-of-freedom, the largest aperture available will not necessarily result in a maximized image central core. The negative effects of atmospheric turbulence, roughly proportional to e(superscript -(D/r(subscript o))(superscript 5/3)), cannot always be compensated by the increased light gathering ability of a larger aperture (proportional to D(superscript 2)). It is shown and verified through simulation that the optimum aperture diameter is a function of N(superscript p) r(subscript o) where N is the number of adaptive optics degrees of freedom and r(subscript o) is the seeing cell size. The simulations show that the exponent p is related to the control algorithm or, more precisely, the figure-of-merit used to drive the deformable mirror actuators. Optimizing the useful aperture of the telescope/adaptive optics system is a strategy that can make use of the variation in site seeing conditions and benefit the astronomer by increasing the available number of observable science objects or reducing the observing time.

  9. Hierarchical Control Strategy for the Cooperative Braking System of Electric Vehicle.

    PubMed

    Peng, Jiankun; He, Hongwen; Liu, Wei; Guo, Hongqiang

    2015-01-01

    This paper provides a hierarchical control strategy for cooperative braking system of an electric vehicle with separated driven axles. Two layers are defined: the top layer is used to optimize the braking stability based on two sliding mode control strategies, namely, the interaxle control mode and signal-axle control strategies; the interaxle control strategy generates the ideal braking force distribution in general braking condition, and the single-axle control strategy can ensure braking safety in emergency braking condition; the bottom layer is used to maximize the regenerative braking energy recovery efficiency with a reallocated braking torque strategy; the reallocated braking torque strategy can recovery braking energy as much as possible in the premise of meeting battery charging power. The simulation results show that the proposed hierarchical control strategy is reasonable and can adapt to different typical road surfaces and load cases; the vehicle braking stability and safety can be guaranteed; furthermore, the regenerative braking energy recovery efficiency can be improved.

  10. Managing work and family: Do control strategies help?

    PubMed

    Versey, H Shellae

    2015-11-01

    How can we effectively manage competing obligations from work and family without becoming overwhelmed? This question inspires the current study by examining control strategies that may facilitate better work-life balance, with a specific focus on the role of lowered aspirations and positive reappraisals, attitudes that underlie adaptive coping behaviors. Data from the Midlife in the United States Survey (MIDUS II) were used to explore the relationship between negative spillover, control strategies, and well-being among full-time working men and women (N = 2,091). In this nationally representative sample, findings indicate that while positive reappraisals function as a protective buffer, lowering aspirations exacerbate the relationship between work-family spillover and well-being, with moderating effects stronger among women. This study extends prior research tying work-life conflict to health and mental health, and suggests further investigation is needed to consider types of resources that may be effective coping strategies in balancing work and family.

  11. Urban plant physiology: adaptation-mitigation strategies under permanent stress.

    PubMed

    Calfapietra, Carlo; Peñuelas, Josep; Niinemets, Ülo

    2015-02-01

    Urban environments that are stressful for plant function and growth will become increasingly widespread in future. In this opinion article, we define the concept of 'urban plant physiology', which focuses on plant responses and long term adaptations to urban conditions and on the capacity of urban vegetation to mitigate environmental hazards in urbanized settings such as air and soil pollution. Use of appropriate control treatments would allow for studies in urban environments to be comparable to expensive manipulative experiments. In this opinion article, we propose to couple two approaches, based either on environmental gradients or manipulated gradients, to develop the concept of urban plant physiology for assessing how single or multiple environmental factors affect the key environmental services provided by urban forests. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Floral thermogenesis: An adaptive strategy of pollination biology in Magnoliaceae.

    PubMed

    Wang, Ruohan; Zhang, Zhixiang

    2015-01-01

    Floral thermogenesis plays a crucial role in pollination biology, especially in plant-pollinator interactions. We have recently explored how thermogenesis is related to pollinator activity and odour release in Magnolia sprengeri. By analyzing flower temperatures, emission of volatiles, and insect visitation, we found that floral blends released during pistillate and staminate stages were similar and coincided with sap beetle visitation. Thus, odour mimicry of staminate-stage flowers may occur during the pistillate stage and may be an adaptive strategy of Magnolia species to attract pollinators during both stages, ensuring successful pollination. In addition to the biological significance of floral thermogenesis in Magnolia species, we explored the underlying regulatory mechanisms via profiling miRNA expression in M. denudata flowers during thermogenic and non-thermogenic stages. We identified 17 miRNAs that may play regulatory roles in floral thermogenesis. Functional annotation of their target genes indicated that these miRNAs regulate floral thermogenesis by influencing cellular respiration and light reactions. These findings increase our understanding of plant-pollinator interactions and the regulatory mechanisms in thermogenic plants.

  13. Floral thermogenesis: An adaptive strategy of pollination biology in Magnoliaceae

    PubMed Central

    Wang, Ruohan; Zhang, Zhixiang

    2015-01-01

    Floral thermogenesis plays a crucial role in pollination biology, especially in plant–pollinator interactions. We have recently explored how thermogenesis is related to pollinator activity and odour release in Magnolia sprengeri. By analyzing flower temperatures, emission of volatiles, and insect visitation, we found that floral blends released during pistillate and staminate stages were similar and coincided with sap beetle visitation. Thus, odour mimicry of staminate-stage flowers may occur during the pistillate stage and may be an adaptive strategy of Magnolia species to attract pollinators during both stages, ensuring successful pollination. In addition to the biological significance of floral thermogenesis in Magnolia species, we explored the underlying regulatory mechanisms via profiling miRNA expression in M. denudata flowers during thermogenic and non-thermogenic stages. We identified 17 miRNAs that may play regulatory roles in floral thermogenesis. Functional annotation of their target genes indicated that these miRNAs regulate floral thermogenesis by influencing cellular respiration and light reactions. These findings increase our understanding of plant–pollinator interactions and the regulatory mechanisms in thermogenic plants. PMID:26844867

  14. Modular and Adaptive Control of Sound Processing

    NASA Astrophysics Data System (ADS)

    van Nort, Douglas

    parameters. In this view, desired gestural dynamics and sonic response are achieved through modular construction of mapping layers that are themselves subject to parametric control. Complementing this view of the design process, the work concludes with an approach in which the creation of gestural control/sound dynamics are considered in the low-level of the underlying sound model. The result is an adaptive system that is specialized to noise-based transformations that are particularly relevant in an electroacoustic music context. Taken together, these different approaches to design and evaluation result in a unified framework for creation of an instrumental system. The key point is that this framework addresses the influence that mapping structure and control dynamics have on the perceived feel of the instrument. Each of the results illustrate this using either top-down or bottom-up approaches that consider musical control context, thereby pointing to the greater potential for refined sonic articulation that can be had by combining them in the design process.

  15. HTGR Resilient Control System Strategy

    SciTech Connect

    Lynne M. Stevens

    2010-09-01

    A preeminent objective for corporate and government organizations is the protection of major investments, which is attained by achieving state awareness, a comprehensive understanding of security and safety, for critical infrastructures. Given the dependence of critical infrastructure on control systems for automation, the integrity of these systems and their ability to provide owner/operators a high degree of state awareness is essential in attaining a high degree of investment protection and public acceptance. Operators as well as government are therefore burdened to ensure they have a timely understanding of the status of their plant or all plants, respectively, to ensure efficient operations and investment and public protection. “This characterization is a significant objective that must consider many aspects of instrumentation, control, and intelligent systems in order to achieve the required result. These aspects include sensory, communication, analysis, decision, and human system interfaces necessary to achieve fusion of data and presentation of results that will provide an understanding of what issues are important and why.

  16. Adaptive fuzzy sliding control of single-phase PV grid-connected inverter

    PubMed Central

    Zhu, Yunkai

    2017-01-01

    In this paper, an adaptive fuzzy sliding mode controller is proposed to control a two-stage single-phase photovoltaic (PV) grid-connected inverter. Two key technologies are discussed in the presented PV system. An incremental conductance method with adaptive step is adopted to track the maximum power point (MPP) by controlling the duty cycle of the controllable power switch of the boost DC-DC converter. An adaptive fuzzy sliding mode controller with an integral sliding surface is developed for the grid-connected inverter where a fuzzy system is used to approach the upper bound of the system nonlinearities. The proposed strategy has strong robustness for the sliding mode control can be designed independently and disturbances can be adaptively compensated. Simulation results of a PV grid-connected system verify the effectiveness of the proposed method, demonstrating the satisfactory robustness and performance. PMID:28797060

  17. Adaptive Control of Visually Guided Grasping in Neural Networks

    DTIC Science & Technology

    1990-03-12

    U01ITU S.WM NONnumsen Adaptive Control of Visually Guided Grasping in Neural Networks AFOSR-89-&CO030 88-NL-209 L AUTHOrSF 2313/A8 00 61102F (V) Dr...FINAL REPORT ADAPTIVE CONTROL OF VISUALLY GUIDED GRASPING IN NEURAL NETWORKS Neurogen Laboratories Inc. Project Summary Research performed for AFOSR...arm’s length in position and 6 degrees in orientation. Keywords: Neural Networks , Adaptive Motor Control, Sensory-Motor sensation Introduction The human

  18. Smart Rehabilitation Devices: Part II - Adaptive Motion Control.

    PubMed

    Dong, Shufang; Lu, Ke-Qian; Sun, J Q; Rudolph, Katherine

    2006-01-01

    This article presents a study of adaptive motion control of smart versatile rehabilitation devices using MR fluids. The device provides both isometric and isokinetic strength training and is reconfigurable for several human joints. Adaptive controls are developed to regulate resistance force based on the prescription of the therapist. Special consideration has been given to the human-machine interaction in the adaptive control that can modify the behavior of the device to account for strength gains or muscle fatigue of the human subject.

  19. Adaptive Cruise Control: Hybrid, Distributed, and Now Formally Verified

    DTIC Science & Technology

    2011-06-01

    Adaptive Cruise Control: Hybrid, Distributed, and Now Formally Verified Sarah M. Loos André Platzer Ligia Nistor JUNE 2011 CMU-CS-11-107 School of...pages 273–288. Springer, 1998. [LPN11a] Sarah M. Loos, André Platzer , and Ligia Nistor. Adaptive cruise control: Hybrid, distributed, and now... Platzer , and Ligia Nistor. Adaptive cruise control: Hybrid, distributed, and now formally verified, 2011. Electronic proof and demo: http

  20. Verification and Tuning of an Adaptive Controller for an Unmanned Air Vehicle

    NASA Technical Reports Server (NTRS)

    Crespo, Luis G.; Matsutani, Megumi; Annaswamy, Anuradha M.

    2010-01-01

    This paper focuses on the analysis and tuning of a controller based on the Adaptive Control Technology for Safe Flight (ACTS) architecture. The ACTS architecture consists of a nominal, non-adaptive controller that provides satisfactory performance under nominal flying conditions, and an adaptive controller that provides robustness under off-nominal ones. A framework unifying control verification and gain tuning is used to make the controller s ability to satisfy the closed-loop requirements more robust to uncertainty. In this paper we tune the gains of both controllers using this approach. Some advantages and drawbacks of adaptation are identified by performing a global robustness assessment of both the adaptive controller and its non-adaptive counterpart. The analyses used to determine these characteristics are based on evaluating the degradation in closed-loop performance resulting from uncertainties having increasing levels of severity. The specific adverse conditions considered can be grouped into three categories: aerodynamic uncertainties, structural damage, and actuator failures. These failures include partial and total loss of control effectiveness, locked-in-place control surface deflections, and engine out conditions. The requirements considered are the peak structural loading, the ability of the controller to track pilot commands, the ability of the controller to keep the aircraft s state within the reliable flight envelope, and the handling/riding qualities of the aircraft. The nominal controller resulting from these tuning strategies was successfully validated using the NASA GTM Flight Test Vehicle.

  1. Optimal emission control strategies for photochemical smog

    SciTech Connect

    Costanza, V.; Seinfeld, J.H.

    1982-02-01

    A study of certain aspects of the selection of reactive hydrocarbon and nitrogen oxide emission reductions for photochemical oxidant abatement is carried out. Optimal emission control paths are defined as those minimizing a total cost function consisting of control cost and ozone dosage contributions. Los Angeles County ozone air quality and control cost data are used to formulate an optimal emission reduction path. The analysis is presented primarily to provide insight into the factors involved in designing oxidant control strategies.

  2. Least-Squares Adaptive Control Using Chebyshev Orthogonal Polynomials

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan T.; Burken, John; Ishihara, Abraham

    2011-01-01

    This paper presents a new adaptive control approach using Chebyshev orthogonal polynomials as basis functions in a least-squares functional approximation. The use of orthogonal basis functions improves the function approximation significantly and enables better convergence of parameter estimates. Flight control simulations demonstrate the effectiveness of the proposed adaptive control approach.

  3. Adaptive Management as an Effective Strategy: Interdisciplinary Perceptions for Natural Resources Management

    NASA Astrophysics Data System (ADS)

    Dreiss, Lindsay M.; Hessenauer, Jan-Michael; Nathan, Lucas R.; O'Connor, Kelly M.; Liberati, Marjorie R.; Kloster, Danielle P.; Barclay, Janet R.; Vokoun, Jason C.; Morzillo, Anita T.

    2017-02-01

    Adaptive management is a well-established approach to managing natural resources, but there is little evidence demonstrating effectiveness of adaptive management over traditional management techniques. Peer-reviewed literature attempts to draw conclusions about adaptive management effectiveness using social perceptions, but those studies are largely restricted to employees of US federal organizations. To gain a more comprehensive insight into perceived adaptive management effectiveness, this study aimed to broaden the suite of disciplines, professional affiliations, and geographic backgrounds represented by both practitioners and scholars. A questionnaire contained a series of questions concerning factors that lead to or inhibit effective management, followed by another set of questions focused on adaptive management. Using a continuum representing strategies of both adaptive management and traditional management, respondents selected those strategies that they perceived as being effective. Overall, characteristics (i.e., strategies, stakeholders, and barriers) identified by respondents as contributing to effective management closely aligned with adaptive management. Responses were correlated to the type of adaptive management experience rather than an individual's discipline, occupational, or regional affiliation. In particular, perceptions of characteristics contributing to adaptive management effectiveness varied between respondents who identified as adaptive management scholars (i.e., no implementation experience) and adaptive management practitioners. Together, these results supported two concepts that make adaptive management effective: practitioners emphasized adaptive management's value as a long-term approach and scholars noted the importance of stakeholder involvement. Even so, more communication between practitioners and scholars regarding adaptive management effectiveness could promote interdisciplinary learning and problem solving for improved

  4. Adaptive Management as an Effective Strategy: Interdisciplinary Perceptions for Natural Resources Management.

    PubMed

    Dreiss, Lindsay M; Hessenauer, Jan-Michael; Nathan, Lucas R; O'Connor, Kelly M; Liberati, Marjorie R; Kloster, Danielle P; Barclay, Janet R; Vokoun, Jason C; Morzillo, Anita T

    2017-02-01

    Adaptive management is a well-established approach to managing natural resources, but there is little evidence demonstrating effectiveness of adaptive management over traditional management techniques. Peer-reviewed literature attempts to draw conclusions about adaptive management effectiveness using social perceptions, but those studies are largely restricted to employees of US federal organizations. To gain a more comprehensive insight into perceived adaptive management effectiveness, this study aimed to broaden the suite of disciplines, professional affiliations, and geographic backgrounds represented by both practitioners and scholars. A questionnaire contained a series of questions concerning factors that lead to or inhibit effective management, followed by another set of questions focused on adaptive management. Using a continuum representing strategies of both adaptive management and traditional management, respondents selected those strategies that they perceived as being effective. Overall, characteristics (i.e., strategies, stakeholders, and barriers) identified by respondents as contributing to effective management closely aligned with adaptive management. Responses were correlated to the type of adaptive management experience rather than an individual's discipline, occupational, or regional affiliation. In particular, perceptions of characteristics contributing to adaptive management effectiveness varied between respondents who identified as adaptive management scholars (i.e., no implementation experience) and adaptive management practitioners. Together, these results supported two concepts that make adaptive management effective: practitioners emphasized adaptive management's value as a long-term approach and scholars noted the importance of stakeholder involvement. Even so, more communication between practitioners and scholars regarding adaptive management effectiveness could promote interdisciplinary learning and problem solving for improved

  5. Computation of Parametric Adaptive Fuzzy Controller for Wood Drying System

    NASA Astrophysics Data System (ADS)

    Situmorang, Zakarias; Wardoyo, Retantyo; Hartati, Sri; Istiyanto, Jazi Eko

    2009-08-01

    The paper reports the computation of parametric adaptive fuzzy controller for used to wood drying system. Parametric of adaptive fuzzy controller is control period system. Control period system is how long time need to hoist of temperature drying or humidity drying if the actuator in on-conditions. The parametric is implemented for control system of wood drying process at prototype chamber with solar is source of energy. The actuator of system is heater, damper and sprayer. From result of measurement, that data were doing to analysis statistic to have the parametric. Whenever the parametric want to implemented with mechanism adaptive. Membership Functions of variable control of system to became something is difficult to have effect to temperature and humidity drying. The result of implemented of adaptive fuzzy control is described in graphic typical. The control system is able to adapt change of humidity drying in system schedule of wood drying system.

  6. Direct adaptive control of wind energy conversion systems using Gaussian networks.

    PubMed

    Mayosky, M A; Cancelo, I E

    1999-01-01

    Grid connected wind energy conversion systems (WECS) present interesting control demands, due to the intrinsic nonlinear characteristics of windmills and electric generators. In this paper a direct adaptive control strategy for WECS control is proposed. It is based on the combination of two control actions: a radial basis zfunction network-based adaptive controller, which drives the tracking error to zero with user specified dynamics, and a supervisory controller, based on crude bounds of the system's nonlinearities. The supervisory controller fires when the finite neural-network approximation properties cannot be guaranteed. The form of the supervisor control and the adaptation law for the neural controller are derived from a Lyapunov analysis of stability. The results are applied to a typical turbine/generator pair, showing the feasibility of the proposed solution.

  7. On the adaptive control of a phased array telescope

    NASA Astrophysics Data System (ADS)

    Jamshidi, M.; Meinhardt, J. A.; Carreras, R. A.; Baciak, M. G.

    1989-09-01

    An adaptive control philosophy known as model-reference adaptive control based on an 'ideal' behavior of the system called 'reference' system is considered. Software and hardware implementation of a model-reference adaptive control (MRAC) for a phased array telescope is discussed. The overall system configuration is presented and a model description of the system from both mathematical formulations and the MATRIXx SYSTEM-BUILD points of view is analyzed. A unified approach to to adaptive control design algorithm using MATRIXx is introduced. It is noted that a digital position monitor plays a focal point in the hardware realization of the MRAC algorithm.

  8. Adaptive-passive vibration control systems for industrial applications

    NASA Astrophysics Data System (ADS)

    Mayer, D.; Pfeiffer, T.; Vrbata, J.; Melz, T.

    2015-04-01

    Tuned vibration absorbers have become common for passive vibration reduction in many industrial applications. Lightly damped absorbers (also called neutralizers) can be used to suppress narrowband disturbances by tuning them to the excitation frequency. If the resonance is adapted in-operation, the performance of those devices can be significantly enhanced, or inertial mass can be decreased. However, the integration of actuators, sensors and control electronics into the system raises new design challenges. In this work, the development of adaptive-passive systems for vibration reduction at an industrial scale is presented. As an example, vibration reduction of a ship engine was studied in a full scale test. Simulations were used to study the feasibility and evaluate the system concept at an early stage. Several ways to adjust the resonance of the neutralizer were evaluated, including piezoelectric actuation and common mechatronic drives. Prototypes were implemented and tested. Since vibration absorbers suffer from high dynamic loads, reliability tests were used to assess the long-term behavior under operational conditions and to improve the components. It was proved that the adaptive systems are capable to withstand the mechanical loads in an industrial application. Also a control strategy had to be implemented in order to track the excitation frequency. The most mature concepts were integrated into the full scale test. An imbalance exciter was used to simulate the engine vibrations at a realistic level experimentally. The neutralizers were tested at varying excitation frequencies to evaluate the tracking capabilities of the control system. It was proved that a significant vibration reduction is possible.

  9. Control of Flow Separation Using Adaptive Airfoils

    NASA Technical Reports Server (NTRS)

    Chandrasekhara, M. S.; Wilder, M. C.; Carr, L. W.; Davis, Sanford S. (Technical Monitor)

    1996-01-01

    A novel way of controlling flow separation is reported. The approach involves using an adaptive airfoil geometry that changes its leading edge shape to adjust to the instantaneous flow at high angles of attack such that the flow over it remains attached. In particular, a baseline NACA 0012 airfoil, whose leading edge curvature could be changed dynamically by 400% was tested under quasi-steady compressible flow conditions. A mechanical drive system was used to produce a rounded leading edge to reduce the strong local flow acceleration around its nose and thus reduce the strong adverse pressure gradient that follows such a rapid acceleration. Tests in steady flow showed that at M = 0.3, the flow separated at about 14 deg. angle of attack for the NACA 0012 profile but could be kept attached up to an angle of about 18 deg by changing the nose curvature. No significant hysteresis effects were observed; the flow could be made to reattach from its separated state at high angles by changing the leading edge curvature.

  10. Adaptive servo control for umbilical mating

    NASA Technical Reports Server (NTRS)

    Zia, Omar

    1988-01-01

    Robotic applications at Kennedy Space Center are unique and in many cases require the fime positioning of heavy loads in dynamic environments. Performing such operations is beyond the capabilities of an off-the-shelf industrial robot. Therefore Robotics Applications Development Laboratory at Kennedy Space Center has put together an integrated system that coordinates state of the art robotic system providing an excellent easy to use testbed for NASA sensor integration experiments. This paper reviews the ways of improving the dynamic response of the robot operating under force feedback with varying dynamic internal perturbations in order to provide continuous stable operations under variable load conditions. The goal is to improve the stability of the system with force feedback using the adaptive control feature of existing system over a wide range of random motions. The effect of load variations on the dynamics and the transfer function (order or values of the parameters) of the system has been investigated, more accurate models of the system have been determined and analyzed.

  11. Neural control of chronic stress adaptation

    PubMed Central

    Herman, James P.

    2013-01-01

    Stress initiates adaptive processes that allow the organism to physiologically cope with prolonged or intermittent exposure to real or perceived threats. A major component of this response is repeated activation of glucocorticoid secretion by the hypothalamo-pituitary-adrenocortical (HPA) axis, which promotes redistribution of energy in a wide range of organ systems, including the brain. Prolonged or cumulative increases in glucocorticoid secretion can reduce benefits afforded by enhanced stress reactivity and eventually become maladaptive. The long-term impact of stress is kept in check by the process of habituation, which reduces HPA axis responses upon repeated exposure to homotypic stressors and likely limits deleterious actions of prolonged glucocorticoid secretion. Habituation is regulated by limbic stress-regulatory sites, and is at least in part glucocorticoid feedback-dependent. Chronic stress also sensitizes reactivity to new stimuli. While sensitization may be important in maintaining response flexibility in response to new threats, it may also add to the cumulative impact of glucocorticoids on the brain and body. Finally, unpredictable or severe stress exposure may cause long-term and lasting dysregulation of the HPA axis, likely due to altered limbic control of stress effector pathways. Stress-related disorders, such as depression and PTSD, are accompanied by glucocorticoid imbalances and structural/ functional alterations in limbic circuits that resemble those seen following chronic stress, suggesting that inappropriate processing of stressful information may be part of the pathological process. PMID:23964212

  12. 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.

  13. Restricted Complexity Framework for Nonlinear Adaptive Control in Complex Systems

    SciTech Connect

    Williams, Rube B.

    2004-02-04

    Control law adaptation that includes implicit or explicit adaptive state estimation, can be a fundamental underpinning for the success of intelligent control in complex systems, particularly during subsystem failures, where vital system states and parameters can be impractical or impossible to measure directly. A practical algorithm is proposed for adaptive state filtering and control in nonlinear dynamic systems when the state equations are unknown or are too complex to model analytically. The state equations and inverse plant model are approximated by using neural networks. A framework for a neural network based nonlinear dynamic inversion control law is proposed, as an extrapolation of prior developed restricted complexity methodology used to formulate the adaptive state filter. Examples of adaptive filter performance are presented for an SSME simulation with high pressure turbine failure to support extrapolations to adaptive control problems.

  14. Restricted Complexity Framework for Nonlinear Adaptive Control in Complex Systems

    NASA Astrophysics Data System (ADS)

    Williams, Rube B.

    2004-02-01

    Control law adaptation that includes implicit or explicit adaptive state estimation, can be a fundamental underpinning for the success of intelligent control in complex systems, particularly during subsystem failures, where vital system states and parameters can be impractical or impossible to measure directly. A practical algorithm is proposed for adaptive state filtering and control in nonlinear dynamic systems when the state equations are unknown or are too complex to model analytically. The state equations and inverse plant model are approximated by using neural networks. A framework for a neural network based nonlinear dynamic inversion control law is proposed, as an extrapolation of prior developed restricted complexity methodology used to formulate the adaptive state filter. Examples of adaptive filter performance are presented for an SSME simulation with high pressure turbine failure to support extrapolations to adaptive control problems.

  15. Synthetic consciousness: the distributed adaptive control perspective

    PubMed Central

    2016-01-01

    Understanding the nature of consciousness is one of the grand outstanding scientific challenges. The fundamental methodological problem is how phenomenal first person experience can be accounted for in a third person verifiable form, while the conceptual challenge is to both define its function and physical realization. The distributed adaptive control theory of consciousness (DACtoc) proposes answers to these three challenges. The methodological challenge is answered relative to the hard problem and DACtoc proposes that it can be addressed using a convergent synthetic methodology using the analysis of synthetic biologically grounded agents, or quale parsing. DACtoc hypothesizes that consciousness in both its primary and secondary forms serves the ability to deal with the hidden states of the world and emerged during the Cambrian period, affording stable multi-agent environments to emerge. The process of consciousness is an autonomous virtualization memory, which serializes and unifies the parallel and subconscious simulations of the hidden states of the world that are largely due to other agents and the self with the objective to extract norms. These norms are in turn projected as value onto the parallel simulation and control systems that are driving action. This functional hypothesis is mapped onto the brainstem, midbrain and the thalamo-cortical and cortico-cortical systems and analysed with respect to our understanding of deficits of consciousness. Subsequently, some of the implications and predictions of DACtoc are outlined, in particular, the prediction that normative bootstrapping of conscious agents is predicated on an intentionality prior. In the view advanced here, human consciousness constitutes the ultimate evolutionary transition by allowing agents to become autonomous with respect to their evolutionary priors leading to a post-biological Anthropocene. This article is part of the themed issue ‘The major synthetic evolutionary transitions’. PMID

  16. Synthetic consciousness: the distributed adaptive control perspective.

    PubMed

    Verschure, Paul F M J

    2016-08-19

    Understanding the nature of consciousness is one of the grand outstanding scientific challenges. The fundamental methodological problem is how phenomenal first person experience can be accounted for in a third person verifiable form, while the conceptual challenge is to both define its function and physical realization. The distributed adaptive control theory of consciousness (DACtoc) proposes answers to these three challenges. The methodological challenge is answered relative to the hard problem and DACtoc proposes that it can be addressed using a convergent synthetic methodology using the analysis of synthetic biologically grounded agents, or quale parsing. DACtoc hypothesizes that consciousness in both its primary and secondary forms serves the ability to deal with the hidden states of the world and emerged during the Cambrian period, affording stable multi-agent environments to emerge. The process of consciousness is an autonomous virtualization memory, which serializes and unifies the parallel and subconscious simulations of the hidden states of the world that are largely due to other agents and the self with the objective to extract norms. These norms are in turn projected as value onto the parallel simulation and control systems that are driving action. This functional hypothesis is mapped onto the brainstem, midbrain and the thalamo-cortical and cortico-cortical systems and analysed with respect to our understanding of deficits of consciousness. Subsequently, some of the implications and predictions of DACtoc are outlined, in particular, the prediction that normative bootstrapping of conscious agents is predicated on an intentionality prior. In the view advanced here, human consciousness constitutes the ultimate evolutionary transition by allowing agents to become autonomous with respect to their evolutionary priors leading to a post-biological Anthropocene.This article is part of the themed issue 'The major synthetic evolutionary transitions'. © 2016 The

  17. Coping strategies and adaptation to coronary artery bypass surgery as experienced by three couples.

    PubMed

    Whitsitt, David R

    2012-01-01

    Coping strategies affect the psychosocial adaptation of couples in which one of the partners has undergone coronary artery bypass grafting. Research has focused on coping strategies of patients and spouses as individuals, but little is known about how couples cope with this procedure. The purpose of this study was to understand couples' coping strategies and their influence on adaptation to bypass surgery. Three couples were recruited from the Cardiac Wellness Institute of Calgary, Alberta, Canada. The descriptive phenomenological psychological method was used to analyze data from 2 interviews with each couple. The analysis revealed a single structure that described the couples' lived experiences. The structure and interview data revealed coping strategies and key factors influencing adaptation postsurgery. Coping strategies, such as redefining the illness, seeking spiritual support, and partnering, enhanced psychosocial adaptation for couples. In addition, marital quality, coping congruence, and shared meaning contributed to effective coping and better adaptation. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Adaptive neuro-control for large flexible structures

    NASA Astrophysics Data System (ADS)

    Krishna Kumar, K.; Montgomery, L.

    1992-12-01

    Special problems related to control system design for large flexible structures include the inherent low damping, wide range of modal frequencies, unmodeled dynamics, and possibility of system failures. Neuro-control, which combines concepts from artificial neural networks and adaptive control is investigated as a solution to some of these problems. Specifically, the roles of neutro-controllers in learning unmodeled dynamics and adaptive control for system failures are investigated. The neuro-controller synthesis procedure and its capabilities in adaptively controlling the structure are demonstrated using a mathematical model of an existing structure, the advanced control evaluation for systems test article located at NASA/Marshall Space Flight Center. Also, the real-time adaptive capability of neuro-controllers is demonstrated via an experiment utilizing a flexible clamped-free beam equipped with an actuator that uses a bang-bang controller.

  19. Experimental investigation of adaptive control of a parallel manipulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Charles C.; Antrazi, Sami S.

    1992-01-01

    The implementation of a joint-space adaptive control scheme used to control non-compliant motion of a Stewart Platform-based Manipulator (SPBM) is presented. The SPBM is used in a facility called the Hardware Real-Time Emulator (HRTE) developed at Goddard Space Flight Center to emulate space operations. The SPBM is comprised of two platforms and six linear actuators driven by DC motors, and possesses six degrees of freedom. The report briefly reviews the development of the adaptive control scheme which is composed of proportional-derivative (PD) controllers whose gains are adjusted by an adaptation law driven by the errors between the desired and actual trajectories of the SPBM actuator lengths. The derivation of the adaptation law is based on the concept of model reference adaptive control (MRAC) and Lyapunov direct method under the assumption that SPBM motion is slow as compared to the controller adaptation rate. An experimental study is conducted to evaluate the performance of the adaptive control scheme implemented to control the SPBM to track a vertical and circular paths under step changes in payload. Experimental results show that the adaptive control scheme provides superior tracking capability as compared to fixed-gain controllers.

  20. Adaptive Force Control For Compliant Motion Of A Robot

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun

    1995-01-01

    Two adaptive control schemes offer robust solutions to problem of stable control of forces of contact between robotic manipulator and objects in its environment. They are called "adaptive admittance control" and "adaptive compliance control." Both schemes involve use of force-and torque sensors that indicate contact forces. These schemes performed well when tested in computational simulations in which they were used to control seven-degree-of-freedom robot arm in executing contact tasks. Choice between admittance or compliance control is dictated by requirements of the application at hand.

  1. Adaptive Neural Control of Uncertain MIMO Nonlinear Systems With State and Input Constraints.

    PubMed

    Chen, Ziting; Li, Zhijun; Chen, C L Philip

    2017-06-01

    An adaptive neural control strategy for multiple input multiple output nonlinear systems with various constraints is presented in this paper. To deal with the nonsymmetric input nonlinearity and the constrained states, the proposed adaptive neural control is combined with the backstepping method, radial basis function neural network, barrier Lyapunov function (BLF), and disturbance observer. By ensuring the boundedness of the BLF of the closed-loop system, it is demonstrated that the output tracking is achieved with all states remaining in the constraint sets and the general assumption on nonsingularity of unknown control coefficient matrices has been eliminated. The constructed adaptive neural control has been rigorously proved that it can guarantee the semiglobally uniformly ultimate boundedness of all signals in the closed-loop system. Finally, the simulation studies on a 2-DOF robotic manipulator system indicate that the designed adaptive control is effective.

  2. Adaptive fuzzy switched control design for uncertain nonholonomic systems with input nonsmooth constraint

    NASA Astrophysics Data System (ADS)

    Li, Yongming; Tong, Shaocheng

    2016-10-01

    In this paper, a fuzzy adaptive switched control approach is proposed for a class of uncertain nonholonomic chained systems with input nonsmooth constraint. In the control design, an auxiliary dynamic system is designed to address the input nonsmooth constraint, and an adaptive switched control strategy is constructed to overcome the uncontrollability problem associated with x0(t0) = 0. By using fuzzy logic systems to tackle unknown nonlinear functions, a fuzzy adaptive control approach is explored based on the adaptive backstepping technique. By constructing the combination approximation technique and using Young's inequality scaling technique, the number of the online learning parameters is reduced to n and the 'explosion of complexity' problem is avoid. It is proved that the proposed method can guarantee that all variables of the closed-loop system converge to a small neighbourhood of zero. Two simulation examples are provided to illustrate the effectiveness of the proposed control approach.

  3. Rapid innate control of antigen abrogates adaptive immunity

    PubMed Central

    Pembroke, Thomas P I; Gallimore, Awen M; Godkin, Andrew

    2013-01-01

    Natural killer (NK) cells provide an immediate first line of defence against viral infections. Memory responses, maintained by CD4+ T cells, require exposure to viral antigen and provide long-term protection against future infections. It is known that NK cells can promote the development of the adaptive response through cytokine production and cross-talk with antigen-presenting cells. In this paper however, we summarize a series of recent publications, in mouse models and for the first time in man, with the unifying message that rapid viral antigen control by the innate immune system limits antigen exposure to CD4+ cells thereby abrogating the development of a memory response. We discuss the significant implication of these studies on viral treatment strategies and immunization models. PMID:23198899

  4. Thermotropic and Thermochromic Polymer Based Materials for Adaptive Solar Control

    PubMed Central

    Seeboth, Arno; Ruhmann, Ralf; Mühling, Olaf

    2010-01-01

    The aim of this review is to present the actual status of development in adaptive solar control by use of thermotropic and organic thermochromic materials. Such materials are suitable for application in smart windows. In detail polymer blends, hydrogels, resins, and thermoplastic films with a reversible temperature-dependent switching behavior are described. A comparative evaluation of the concepts for these energy efficient materials is given as well. Furthermore, the change of strategy from ordinary shadow systems to intrinsic solar energy reflection materials based on phase transition components and a first remark about their realization is reported. Own current results concerning extruded films and high thermally stable casting resins with thermotropic properties make a significant contribution to this field. PMID:28883374

  5. Land Use Adaptation Strategies Analysis in Landslide Risk Region

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Ching; Chang, Chin-Hsin; Chen, Ying-Tung

    2013-04-01

    In order to respond to the impact of climate and environmental change on Taiwanese mountain region, this study used GTZ (2004) Risk analysis guidelines to assess the landslide risk for 178 Taiwanese mountain towns. This study used 7 indicators to assess landslide risk, which are rainfall distribution, natural environment vulnerability (e.g., rainfall threshold criterion for debris flow, historical disaster frequency, landslide ratio, and road density), physicality vulnerability (e.g., population density) and socio-economic vulnerability (e.g., population with higher education, death rate and income). The landslide risk map can be obtained by multiplying 7 indicators together and ranking the product. The map had 5 risk ranges, and towns within the range of 4 to 5, which are high landslide risk regions, and have high priority in reducing risk. This study collected the regions with high landslide risk regions and analyzed the difference after Typhoon Morakot (2009). The spatial distribution showed that after significant environmental damage high landslide risk regions moved from central to south Taiwan. The changeable pattern of risk regions pointed out the necessity of updating the risk map periodically. Based on the landslide risk map and the land use investigation data which was provided by the National Land Surveying and Mapping Center in 2007, this study calculated the size of the land use area with landslide disaster risk. According to the above results and discussion, this study can be used to suggest appropriate land use adaptation strategies provided for reducing landslide risk under the impact of climate and environmental change.

  6. Adaptive strategies for nitrogen metabolism in phosphate deficient legume nodules.

    PubMed

    Valentine, Alex J; Kleinert, Aleysia; Benedito, Vagner A

    2017-03-01

    Legumes play a significant role in natural and agricultural ecosystems. They can fix atmospheric N2 and contribute the fixed N to soils and plant N budgets. In legumes, the availability of P does not only affect nodule development, but also N acquisition and metabolism. For legumes as an important source of plant proteins, their capacity to metabolise N during P deficiency is critical for their benefits to agriculture and the natural environment. In particular for farming, rock P is a non-renewable source of which the world has about 60-80 years of sustainable extraction of this P left. The global production of legume crops would be devastated during a scarcity of P fertiliser. Legume nodules have a high requirement for mineral P, which makes them vulnerable to soil P deficiencies. In order to maintain N metabolism, the nodules have evolved several strategies to resist the immediate effects of P limitation and to respond to prolonged P deficiency. In legumes nodules, N metabolism is determined by several processes involving the acquisition, assimilation, export, and recycling of N in various forms. Although these processes are integrated, the current literature lacks a clear synthesis of how legumes respond to P stress regarding its impact on N metabolism. In this review, we synthesise the current state of knowledge on how legumes maintain N metabolism during P deficiency. Moreover, we discuss the potential importance of two additional alterations to N metabolism during P deficiency. Our goals are to place these newly proposed mechanisms in perspective with other known adaptations of N metabolism to P deficiency and to discuss their practical benefits during P deficiency in legumes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Pulse front control with adaptive optics

    NASA Astrophysics Data System (ADS)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The focusing of ultrashort laser pulses is extremely important for processes including microscopy, laser fabrication and fundamental science. Adaptive optic elements, such as liquid crystal spatial light modulators or membrane deformable mirrors, are routinely used for the correction of aberrations in these systems, leading to improved resolution and efficiency. Here, we demonstrate that adaptive elements used with ultrashort pulses should not be considered simply in terms of wavefront modification, but that changes to the incident pulse front can also occur. We experimentally show how adaptive elements may be used to engineer pulse fronts with spatial resolution.

  8. Adaptive Control Techniques for Large Space Structures

    DTIC Science & Technology

    1989-01-06

    Point Analy- sis", submitted, IEEE Trans. on Circuits and Systems; Special Issue on Adaptive Systems, Sept. 1987. I.M.Y. Mareels, R.R. Bitmead, M. Gevers...adaptive system with unmodelled dynamics," Proc. IFAC Workshop on Adaptive Systems, San Francisco, CA. C.A. Desoer , R.W. Liu, J. Murray and R. Sacks...June 1980. C.A. Desoer and M. Vidyasagar, Feedback Systems: Input-Output Properties, Academic Press, * 1975. J.C. Doyle and G. Stein (1981

  9. Enhanced vaccine control of epidemics in adaptive networks.

    PubMed

    Shaw, Leah B; Schwartz, Ira B

    2010-04-01

    We study vaccine control for disease spread on an adaptive network modeling disease avoidance behavior. Control is implemented by adding Poisson-distributed vaccination of susceptibles. We show that vaccine control is much more effective in adaptive networks than in static networks due to feedback interaction between the adaptive network rewiring and the vaccine application. When compared to extinction rates in static social networks, we find that the amount of vaccine resources required to sustain similar rates of extinction are as much as two orders of magnitude lower in adaptive networks.

  10. Adaptive and Optimal Control of Stochastic Dynamical Systems

    DTIC Science & Technology

    2015-09-14

    control and stochastic differential games . Stochastic linear-quadratic, continuous time, stochastic control problems are solved for systems with noise...control problems for systems with arbitrary correlated n 15. SUBJECT TERMS Adaptive control, optimal control, stochastic differential games 16. SECURITY...explicit results have been obtained for problems of stochastic control and stochastic differential games . Stochastic linear- quadratic, continuous time

  11. Fractional adaptive control for an automatic voltage regulator.

    PubMed

    Aguila-Camacho, Norelys; Duarte-Mermoud, Manuel A

    2013-11-01

    This paper presents the application of a direct Fractional Order Model Reference Adaptive Controller (FOMRAC) to an Automatic Voltage Regulator (AVR). A direct FOMRAC is a direct Model Reference Adaptive Control (MRAC), whose controller parameters are adjusted using fractional order differential equations. Four realizations of the FOMRAC were designed in this work, each one considering different orders for the plant model. The design procedure consisted of determining the optimal values of the fractional order and the adaptive gains for each adaptive law, using Genetic algorithm optimization. Comparisons were made among the four FOMRAC designs, a fractional order PID (FOPID), a classical PID, and four Integer Order Model Reference Adaptive Controllers (IOMRAC), showing that the FOMRAC can improve the controlled system behavior and its robustness with respect to model uncertainties. Finally, some performance indices are presented here for the controlled schemes, in order to show the advantages and disadvantages of the FOMRAC.

  12. Adaptive control of bivalirudin in the cardiac intensive care unit.

    PubMed

    Zhao, Qi; Edrich, Thomas; Paschalidis, Ioannis Ch

    2015-02-01

    Bivalirudin is a direct thrombin inhibitor used in the cardiac intensive care unit when heparin is contraindicated due to heparin-induced thrombocytopenia. Since it is not a commonly used drug, clinical experience with its dosing is sparse. In earlier work [1], we developed a dynamic system model that accurately predicts the effect of bivalirudin given dosage over time and patient physiological characteristics. This paper develops adaptive dosage controllers that regulate its effect to desired levels. To that end, and in the case that bivalirudin model parameters are available, we develop a Model Reference Control law. In the case that model parameters are unknown, an indirect Model Reference Adaptive Control scheme is applied to estimate model parameters first and then adapt the controller. Alternatively, direct Model Reference Adaptive Control is applied to adapt the controller directly without estimating model parameters first. Our algorithms are validated using actual patient data from a large hospital in the Boston area.

  13. Adaptive backstepping control for three axis microsatellite attitude pointing under actuator faults

    NASA Astrophysics Data System (ADS)

    MOHAMMED, M. A. SI; BOUSSADIA, H.; BELLAR, A.; ADNANE, A.

    2017-01-01

    This paper presents the design of Low Earth Orbit (LEO) micro-satellite attitude controller using reaction wheels, and under actuator faults. Firstly, a backstepping controller is developed when the actuator is fault-free. Then, a fault tolerant controller is designed to compensate the actuator fault. Two types of this latter are considered (additive and multiplicative faults). The presented control strategy is based on adaptive backstepping technique. The simulation results clearly demonstrate the effectiveness of the presented technique.

  14. Strategies for improving adaptation practice in developing countries

    NASA Astrophysics Data System (ADS)

    Conway, Declan; Mustelin, Johanna

    2014-05-01

    The international community's support for adaptation in developing countries has proliferated through numerous complementary funding mechanisms. A range of serious practical issues are emerging, however, as adaptation moves from theory and international negotiation to implementation. We identify three areas deserving greater scrutiny: in-country priorities, entry points and delivery systems, and provide recommendations for improving adaptation practice. These concerns, if not addressed, have the potential to hamper attempts at effective delivery and to increase the vulnerability of intended beneficiaries of the adaptation agenda.

  15. Monitoring the Performance of a Neuro-Adaptive Controller

    NASA Technical Reports Server (NTRS)

    Schumann, Johann; Gupta, Pramod

    2004-01-01

    Traditional control has proven to be ineffective to deal with catastrophic changes or slow degradation of complex, highly nonlinear systems like aircraft or spacecraft, robotics, or flexible manufacturing systems. Control systems which can adapt toward changes in the plant have been proposed as they offer many advantages (e.g., better performance, controllability of aircraft despite of a damaged wing). In the last few years, use of neural networks in adaptive controllers (neuro-adaptive control) has been studied actively. Neural networks of various architectures have been used successfully for online learning adaptive controllers. In such a typical control architecture, the neural network receives as an input the current deviation between desired and actual plant behavior and, by on-line training, tries to minimize this discrepancy (e.g.; by producing a control augmentation signal). Even though neuro-adaptive controllers offer many advantages, they have not been used in mission- or safety-critical applications, because performance and safety guarantees cannot b e provided at development time-a major prerequisite for safety certification (e.g., by the FAA or NASA). Verification and Validation (V&V) of an adaptive controller requires the development of new analysis techniques which can demonstrate that the control system behaves safely under all operating conditions. Because of the requirement to adapt toward unforeseen changes during operation, i.e., in real time, design-time V&V is not sufficient.

  16. Monitoring the Performance of a Neuro-Adaptive Controller

    NASA Technical Reports Server (NTRS)

    Schumann, Johann; Gupta, Pramod

    2004-01-01

    Traditional control has proven to be ineffective to deal with catastrophic changes or slow degradation of complex, highly nonlinear systems like aircraft or spacecraft, robotics, or flexible manufacturing systems. Control systems which can adapt toward changes in the plant have been proposed as they offer many advantages (e.g., better performance, controllability of aircraft despite of a damaged wing). In the last few years, use of neural networks in adaptive controllers (neuro-adaptive control) has been studied actively. Neural networks of various architectures have been used successfully for online learning adaptive controllers. In such a typical control architecture, the neural network receives as an input the current deviation between desired and actual plant behavior and, by on-line training, tries to minimize this discrepancy (e.g.; by producing a control augmentation signal). Even though neuro-adaptive controllers offer many advantages, they have not been used in mission- or safety-critical applications, because performance and safety guarantees cannot b e provided at development time-a major prerequisite for safety certification (e.g., by the FAA or NASA). Verification and Validation (V&V) of an adaptive controller requires the development of new analysis techniques which can demonstrate that the control system behaves safely under all operating conditions. Because of the requirement to adapt toward unforeseen changes during operation, i.e., in real time, design-time V&V is not sufficient.

  17. Low Activity Waste Feed Process Control Strategy

    SciTech Connect

    STAEHR, T.W.

    2000-06-14

    The primary purpose of this document is to describe the overall process control strategy for monitoring and controlling the functions associated with the Phase 1B high-level waste feed delivery. This document provides the basis for process monitoring and control functions and requirements needed throughput the double-shell tank system during Phase 1 high-level waste feed delivery. This document is intended to be used by (1) the developers of the future Process Control Plan and (2) the developers of the monitoring and control system.

  18. Sense of Control and Career Adaptability among Undergraduate Students

    ERIC Educational Resources Information Center

    Duffy, Ryan D.

    2010-01-01

    The current study examined the direct relation of sense of control to career adaptability, as well as its ability to function as a mediator for other established predictors, with a sample of 1,991 undergraduate students. Students endorsing a greater sense of personal control were more likely to view themselves as adaptable to the world of work.…

  19. Sense of Control and Career Adaptability among Undergraduate Students

    ERIC Educational Resources Information Center

    Duffy, Ryan D.

    2010-01-01

    The current study examined the direct relation of sense of control to career adaptability, as well as its ability to function as a mediator for other established predictors, with a sample of 1,991 undergraduate students. Students endorsing a greater sense of personal control were more likely to view themselves as adaptable to the world of work.…

  20. Adaptive controller for a needle free jet-injector system.

    PubMed

    Modak, Ashin; Hogan, N Catherine; Hunter, Ian W

    2015-01-01

    A nonlinear, sliding mode adaptive controller was created for a needle-free jet injection system. The controller was based on a simplified lumped-sum parameter model of the jet-injection mechanics. The adaptive control scheme was compared to a currently-used Feed-forward+PID controller in both ejection of water into air, and injection of dye into ex-vivo porcine tissue. The adaptive controller was more successful in trajectory tracking and was more robust to the biological variations caused by a tissue load.

  1. [Discussion of HIV control and prevention strategies].

    PubMed

    Lyu, P

    2016-10-06

    Expansion of HIV testing and ART treatment are core strategies for achieving the ambitious global goal of ending the HIV epidemic by the end of 2030, and achieving the "90-90-90" target by 2020. In China, great progress in HIV control and prevention has been made; however, there is room to enhance the effectiveness of HIV-related strategies. In addition, some implemented strategies have not achieved their expected output. To confront the challenge of sexual transmission of HIV, which is the main route of transmission in China, more targeted HIV prevention strategies that lead to their expected outcomes are essential. It is important to strengthen existing strategies that have been proved effective. However, it is also critical to create innovative strategies, and there are five approaches to achieve this. First, a holistic perspective should be adopted, to better understand the current situation and problems. This means intervention strategies should give serious consideration of how to meet the sociocultural needs of target populations rather than merely carry out behavioral interventions. Second, community-based HIV prevention settings should have more important roles in providing HIV-related health care services. Moreover, to improve the effectiveness of these strategies, a problem-led working style should be integrated into HIV prevention measures overall. Third, thoroughly analyzing characteristics of the current HIV epidemic using more evidence-based considerations must be undertaken, to better control HIV sexual transmission. Fourth, continued improvement of AIDS prevention and control mechanisms is needed, to ensure their sustainable development. Last, it is necessary to involve more NGOs in HIV prevention work by strengthening their management and working capacities to provide HIV-related services. Also needed is further improvement in both technical and management capacities, so as to build a stable basis for effective response.

  2. Adaptive Dynamic Range Optimization (ADRO): A Digital Amplification Strategy for Hearing Aids and Cochlear Implants

    PubMed Central

    Blamey, Peter J.

    2005-01-01

    Adaptive dynamic range optimization (ADRO) is an amplification strategy that uses digital signal processing techniques to improve the audibility, comfort, and intelligibility of sounds for people who use cochlear implants and/or hearing aids. The strategy uses statistical analysis to select the most information-rich section of the input dynamic range in multiple-frequency channels. Fuzzy logic rules control the gain in each frequency channel so that the selected section of the dynamic range is presented at an audible and comfortable level. The ADRO processing thus adaptively optimizes the dynamic range of the signal in multiple-frequency channels. Clinical studies show that ADRO can be fitted easily to all degrees of hearing loss for hearing aids and cochlear implants in a direct and intuitive manner, taking the preferences of the listener into account. The result is high acceptance by new and experienced hearing aid users and strong preferences for ADRO compared with alternative amplification strategies. The ADRO processing is particularly well suited to bimodal and hybrid stimulation which combine electric and acoustic stimulation in opposite ears or in the same ear, respectively. PMID:16012705

  3. Adaptive Work Strategy for Evaluating a Conceptual Site Model

    NASA Astrophysics Data System (ADS)

    Dietrich, P.; Utom, A. U.; Werban, U.

    2015-12-01

    A comprehensive, diagnostic, procedural and adaptive scheme involving a combination of geophysical and direct push methods was developed and applied in the Wurmlingen study site situated within the region of Baden-Württemberg (southwest Germany). The goal of the study was to test the applicability of electrical resistivity method in imaging resistivity contrasts, and mapping the depth to and lateral extent of field-scale subsurface structures and existence of flow paths that may control concentration gradients of groundwater solution contents. Based on a relatively fast and cost-effective areal mapping with vertical electrical sounding technique, a northwest-southeast trending stream-channel-like depression (low apparent resistivity feature) through a Pleistocene aquifer was detected. For a more detailed characterization, we implemented electrical resistivity tomography method followed by direct push (DP) technologies. Beside the use of DP for verification of structures identified by geophysical tools, we used it for multi-level groundwater sampling. Results from groundwater chemistry indicate zones of steep nitrate concentration gradients associated with the feature.

  4. Closing the Certification Gaps in Adaptive Flight Control Software

    NASA Technical Reports Server (NTRS)

    Jacklin, Stephen A.

    2008-01-01

    Over the last five decades, extensive research has been performed to design and develop adaptive control systems for aerospace systems and other applications where the capability to change controller behavior at different operating conditions is highly desirable. Although adaptive flight control has been partially implemented through the use of gain-scheduled control, truly adaptive control systems using learning algorithms and on-line system identification methods have not seen commercial deployment. The reason is that the certification process for adaptive flight control software for use in national air space has not yet been decided. The purpose of this paper is to examine the gaps between the state-of-the-art methodologies used to certify conventional (i.e., non-adaptive) flight control system software and what will likely to be needed to satisfy FAA airworthiness requirements. These gaps include the lack of a certification plan or process guide, the need to develop verification and validation tools and methodologies to analyze adaptive controller stability and convergence, as well as the development of metrics to evaluate adaptive controller performance at off-nominal flight conditions. This paper presents the major certification gap areas, a description of the current state of the verification methodologies, and what further research efforts will likely be needed to close the gaps remaining in current certification practices. It is envisioned that closing the gap will require certain advances in simulation methods, comprehensive methods to determine learning algorithm stability and convergence rates, the development of performance metrics for adaptive controllers, the application of formal software assurance methods, the application of on-line software monitoring tools for adaptive controller health assessment, and the development of a certification case for adaptive system safety of flight.

  5. Adaptive Fuzzy Bounded Control for Consensus of Multiple Strict-Feedback Nonlinear Systems.

    PubMed

    Wang, Wei; Tong, Shaocheng

    2017-01-10

    This paper studies the adaptive fuzzy bounded control problem for leader-follower multiagent systems, where each follower is modeled by the uncertain nonlinear strict-feedback system. Combining the fuzzy approximation with the dynamic surface control, an adaptive fuzzy control scheme is developed to guarantee the output consensus of all agents under directed communication topologies. Different from the existing results, the bounds of the control inputs are known as a priori, and they can be determined by the feedback control gains. To realize smooth and fast learning, a predictor is introduced to estimate each error surface, and the corresponding predictor error is employed to learn the optimal fuzzy parameter vector. It is proved that the developed adaptive fuzzy control scheme guarantees the uniformly ultimate boundedness of the closed-loop systems, and the tracking error converges to a small neighborhood of the origin. The simulation results and comparisons are provided to show the validity of the control strategy presented in this paper.

  6. Adaptive Instructional Strategies for Teaching Rules in Mathematics.

    ERIC Educational Resources Information Center

    Ross, Steven M.; Rakow, Ernest A.

    1982-01-01

    Describes research on an adaptation approach designed to extend the aptitude treatment interaction (ATI) concept by applying instructional variations to individuals as opposed to groups within the context of an introductory mathematics lesson adapted from the beginning module in an undergraduate statistics course. A 17-item reference list is…

  7. Management Strategies for Complex Adaptive Systems: Sensemaking, Learning, and Improvisation

    ERIC Educational Resources Information Center

    McDaniel, Reuben R., Jr.

    2007-01-01

    Misspecification of the nature of organizations may be a major reason for difficulty in achieving performance improvement. Organizations are often viewed as machine-like, but complexity science suggests that organizations should be viewed as complex adaptive systems. I identify the characteristics of complex adaptive systems and give examples of…

  8. Adaptive jitter control for tracker line of sight stabilization

    NASA Astrophysics Data System (ADS)

    Gibson, Steve; Tsao, Tsu-Chin; Herrick, Dan; Beairsto, Christopher; Grimes, Ronnie; Harper, Todd; Radtke, Jeff; Roybal, Benito; Spray, Jay; Squires, Stephen; Tellez, Dave; Thurston, Michael

    2010-08-01

    A field test experiment on a range tracking telescope at the U. S. Army's White Sands Missile Range is exploring the use of recently developed adaptive control methods to minimize track loop jitter. Gimbal and platform vibration are the main sources of jitter in the experiments, although atmospheric turbulence also is a factor. In initial experiments, the adaptive controller reduced the track loop jitter significantly in frequency ranges beyond the bandwidth of the existing track loop. This paper presents some of the initial experimental results along with analysis of the performance of the adaptive control loop. The paper also describes the adaptive control scheme, its implementation on the WSMR telescope and the system identification required for adaptive control.

  9. Dynamics modeling and adaptive control of flexible manipulators

    NASA Technical Reports Server (NTRS)

    Sasiadek, J. Z.

    1991-01-01

    An application of Model Reference Adaptive Control (MRAC) to the position and force control of flexible manipulators and robots is presented. A single-link flexible manipulator is analyzed. The problem was to develop a mathematical model of a flexible robot that is accurate. The objective is to show that the adaptive control works better than 'conventional' systems and is suitable for flexible structure control.

  10. Adaptive sliding mode control for a class of chaotic systems

    NASA Astrophysics Data System (ADS)

    Farid, R.; Ibrahim, A.; Zalam, B.

    2015-03-01

    Chaos control here means to design a controller that is able to mitigating or eliminating the chaos behavior of nonlinear systems that experiencing such phenomenon. In this paper, an Adaptive Sliding Mode Controller (ASMC) is presented based on Lyapunov stability theory. The well known Chua's circuit is chosen to be our case study in this paper. The study shows the effectiveness of the proposed adaptive sliding mode controller.

  11. Adaptive sliding mode control for a class of chaotic systems

    SciTech Connect

    Farid, R.; Ibrahim, A.; Zalam, B.

    2015-03-30

    Chaos control here means to design a controller that is able to mitigating or eliminating the chaos behavior of nonlinear systems that experiencing such phenomenon. In this paper, an Adaptive Sliding Mode Controller (ASMC) is presented based on Lyapunov stability theory. The well known Chua's circuit is chosen to be our case study in this paper. The study shows the effectiveness of the proposed adaptive sliding mode controller.

  12. FAB (Functionally Alert Behavior Strategies) to Improve Self-Control

    ERIC Educational Resources Information Center

    Pagano, John

    2015-01-01

    This paper describes the FAB (Functionally Alert Behavior) Strategies approach to improve behavior in children and adolescents with complex behavioral challenges. FAB Strategies include evidence-based environmental adaptations, sensory modulation, positive behavioral support, and physical self-regulation strategies. FAB Strategies can be used by…

  13. Systems and Methods for Derivative-Free Adaptive Control

    NASA Technical Reports Server (NTRS)

    Yucelen, Tansel (Inventor); Kim, Kilsoo (Inventor); Calise, Anthony J. (Inventor)

    2015-01-01

    An adaptive control system is disclosed. The control system can control uncertain dynamic systems. The control system can employ one or more derivative-free adaptive control architectures. The control system can further employ one or more derivative-free weight update laws. The derivative-free weight update laws can comprise a time-varying estimate of an ideal vector of weights. The control system of the present invention can therefore quickly stabilize systems that undergo sudden changes in dynamics, caused by, for example, sudden changes in weight. Embodiments of the present invention can also provide a less complex control system than existing adaptive control systems. The control system can control aircraft and other dynamic systems, such as, for example, those with non-minimum phase dynamics.

  14. Turnaround Management Strategies: The Adaptive Model and the Constructive Model. ASHE 1983 Annual Meeting Paper.

    ERIC Educational Resources Information Center

    Chaffee, Ellen E.

    The use of two management strategies by 14 liberal arts and comprehensive colleges attempting to recover from serious financial decline during 1973-1976 were studied. The adaptive model of strategy, based on resource dependence, involves managing demands in order to satisfy critical-resource providers. The constructive model of strategy, based on…

  15. 77 FR 2996 - National Fish, Wildlife, and Plants Climate Adaptation Strategy

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-20

    ... natural systems provide, in a changing climate. In addition to this request for written comments, several..., Wildlife, and Plants Climate Adaptation Strategy (Strategy). The adverse impacts of climate change... wildlife and society against the effects of climate change. When finalized, this draft Strategy will...

  16. Leaf Area Adjustment As an Optimal Drought-Adaptation Strategy

    NASA Astrophysics Data System (ADS)

    Manzoni, S.; Beyer, F.; Thompson, S. E.; Vico, G.; Weih, M.

    2014-12-01

    Leaf phenology plays a major role in land-atmosphere mass and energy exchanges. Much work has focused on phenological responses to light and temperature, but less to leaf area changes during dry periods. Because the duration of droughts is expected to increase under future climates in seasonally-dry as well as mesic environments, it is crucial to (i) predict drought-related phenological changes and (ii) to develop physiologically-sound models of leaf area dynamics during dry periods. Several optimization criteria have been proposed to model leaf area adjustment as soil moisture decreases. Some theories are based on the plant carbon (C) balance, hypothesizing that leaf area will decline when instantaneous net photosynthetic rates become negative (equivalent to maximization of cumulative C gain). Other theories draw on hydraulic principles, suggesting that leaf area should adjust to either maintain a constant leaf water potential (isohydric behavior) or to avoid leaf water potentials with negative impacts on photosynthesis (i.e., minimization of water stress). Evergreen leaf phenology is considered as a control case. Merging these theories into a unified framework, we quantify the effect of phenological strategy and climate forcing on the net C gain over the entire growing season. By accounting for the C costs of leaf flushing and the gains stemming from leaf photosynthesis, this metric assesses the effectiveness of different phenological strategies, under different climatic scenarios. Evergreen species are favored only when the dry period is relatively short, as they can exploit most of the growing season, and only incur leaf maintenance costs during the short dry period. In contrast, deciduous species that lower maintenance costs by losing leaves are advantaged under drier climates. Moreover, among drought-deciduous species, isohydric behavior leads to lowest C gains. Losing leaves gradually so as to maintain a net C uptake equal to zero during the driest period in

  17. The influence of context on the implementation of adaptive emotion regulation strategies.

    PubMed

    Aldao, Amelia; Nolen-Hoeksema, Susan

    2012-08-01

    Putatively adaptive emotion regulation strategies (e.g., acceptance, problem solving, reappraisal) show weaker associations with psychopathology than putatively maladaptive strategies (e.g., avoidance, self-criticism, hiding expression, suppression of experience, worry, rumination). This is puzzling, given the central role that adaptive strategies play in a wide range of psychotherapeutic approaches. We explored this asymmetry by examining the effects of context (i.e., emotion intensity, type of emotion, social vs. academic circumstances) on the implementation of adaptive and maladaptive strategies. We asked 111 participants to describe 8 emotion-eliciting situations and identify which strategies they used in order to regulate their affect. We found support for a contextual model of emotion regulation, in which adaptive strategies were implemented with more cross-situational variability than maladaptive strategies. In addition, the variability in implementation of two adaptive strategies (acceptance, problem solving) predicted lower levels of psychopathology, suggesting that flexible implementation of such strategies in line with contextual demands is associated with better mental health. We discuss these findings by underscoring the importance of adopting a functional approach to the delineation of contextual factors that influence the implementation of emotion regulation strategies.

  18. Internal Models in Sensorimotor Integration: Perspectives from Adaptive Control Theory

    PubMed Central

    Tin, Chung; Poon, Chi-Sang

    2007-01-01

    Internal model and adaptive control are empirical and mathematical paradigms that have evolved separately to describe learning control processes in brain systems and engineering systems, respectively. This paper presents a comprehensive appraisal of the correlation between these paradigms with a view to forging a unified theoretical framework that may benefit both disciplines. It is suggested that the classic equilibrium-point theory of impedance control of arm movement is analogous to continuous gain-scheduling or high-gain adaptive control within or across movement trials, respectively, and that the recently proposed inverse internal model is akin to adaptive sliding control originally for robotic manipulator applications. Modular internal models architecture for multiple motor tasks is a form of multi-model adaptive control. Stochastic methods such as generalized predictive control, reinforcement learning, Bayesian learning and Hebbian feedback covariance learning are reviewed and their possible relevance to motor control is discussed. Possible applicability of Luenberger observer and extended Kalman filter to state estimation problems such as sensorimotor prediction or the resolution of vestibular sensory ambiguity is also discussed. The important role played by vestibular system identification in postural control suggests an indirect adaptive control scheme whereby system states or parameters are explicitly estimated prior to the implementation of control. This interdisciplinary framework should facilitate the experimental elucidation of the mechanisms of internal model in sensorimotor systems and the reverse engineering of such neural mechanisms into novel brain-inspired adaptive control paradigms in future. PMID:16135881

  19. Direct Adaptive Control Methodologies for Flexible-Joint Space Manipulators with Uncertainties and Modeling Errors

    NASA Astrophysics Data System (ADS)

    Ulrich, Steve

    This work addresses the direct adaptive trajectory tracking control problem associated with lightweight space robotic manipulators that exhibit elastic vibrations in their joints, and which are subject to parametric uncertainties and modeling errors. Unlike existing adaptive control methodologies, the proposed flexible-joint control techniques do not require identification of unknown parameters, or mathematical models of the system to be controlled. The direct adaptive controllers developed in this work are based on the model reference adaptive control approach, and manage modeling errors and parametric uncertainties by time-varying the controller gains using new adaptation mechanisms, thereby reducing the errors between an ideal model and the actual robot system. More specifically, new decentralized adaptation mechanisms derived from the simple adaptive control technique and fuzzy logic control theory are considered in this work. Numerical simulations compare the performance of the adaptive controllers with a nonadaptive and a conventional model-based controller, in the context of 12.6 m xx 12.6 m square trajectory tracking. To validate the robustness of the controllers to modeling errors, a new dynamics formulation that includes several nonlinear effects usually neglected in flexible-joint dynamics models is proposed. Results obtained with the adaptive methodologies demonstrate an increased robustness to both uncertainties in joint stiffness coefficients and dynamics modeling errors, as well as highly improved tracking performance compared with the nonadaptive and model-based strategies. Finally, this work considers the partial state feedback problem related to flexible-joint space robotic manipulators equipped only with sensors that provide noisy measurements of motor positions and velocities. An extended Kalman filter-based estimation strategy is developed to estimate all state variables in real-time. The state estimation filter is combined with an adaptive

  20. Multiple Model Parameter Adaptive Control for In-Flight Simulation.

    DTIC Science & Technology

    1988-03-01

    dynamics of an aircraft. The plant is control- lable by a proportional-plus-integral ( PI ) control law. This section describes two methods of calculating...adaptive model-following PI control law [20-24]. The control law bases its control gains upon the parameters of a linear difference equation model which

  1. Parameter testing for lattice filter based adaptive modal control systems

    NASA Technical Reports Server (NTRS)

    Sundararajan, N.; Williams, J. P.; Montgomery, R. C.

    1983-01-01

    For Large Space Structures (LSS), an adaptive control system is highly desirable. The present investigation is concerned with an 'indirect' adaptive control scheme wherein the system order, mode shapes, and modal amplitudes are estimated on-line using an identification scheme based on recursive, least-squares, lattice filters. Using the identified model parameters, a modal control law based on a pole-placement scheme with the objective of vibration suppression is employed. A method is presented for closed loop adaptive control of a flexible free-free beam. The adaptive control scheme consists of a two stage identification scheme working in series and a modal pole placement control scheme. The main conclusion from the current study is that the identified parameters cannot be directly used for controller design purposes.

  2. Parameter testing for lattice filter based adaptive modal control systems

    NASA Technical Reports Server (NTRS)

    Sundararajan, N.; Williams, J. P.; Montgomery, R. C.

    1983-01-01

    For Large Space Structures (LSS), an adaptive control system is highly desirable. The present investigation is concerned with an 'indirect' adaptive control scheme wherein the system order, mode shapes, and modal amplitudes are estimated on-line using an identification scheme based on recursive, least-squares, lattice filters. Using the identified model parameters, a modal control law based on a pole-placement scheme with the objective of vibration suppression is employed. A method is presented for closed loop adaptive control of a flexible free-free beam. The adaptive control scheme consists of a two stage identification scheme working in series and a modal pole placement control scheme. The main conclusion from the current study is that the identified parameters cannot be directly used for controller design purposes.

  3. An averaging analysis of discrete-time indirect adaptive control

    NASA Technical Reports Server (NTRS)

    Phillips, Stephen M.; Kosut, Robert L.; Franklin, Gene F.

    1988-01-01

    An averaging analysis of indirect, discrete-time, adaptive control systems is presented. The analysis results in a signal-dependent stability condition and accounts for unmodeled plant dynamics as well as exogenous disturbances. This analysis is applied to two discrete-time adaptive algorithms: an unnormalized gradient algorithm and a recursive least-squares (RLS) algorithm with resetting. Since linearization and averaging are used for the gradient analysis, a local stability result valid for small adaptation gains is found. For RLS with resetting, the assumption is that there is a long time between resets. The results for the two algorithms are virtually identical, emphasizing their similarities in adaptive control.

  4. Adaptive control with variable dead-zone nonlinearities

    NASA Technical Reports Server (NTRS)

    Orlicki, D.; Valavani, L.; Athans, M.; Stein, G.

    1984-01-01

    It has been found that fixed error dead-zones as defined in the existing literature result in serious degradation of performance, due to the conservativeness which characterizes the determination of their width. In the present paper, variable width dead-zones are derived for the adaptive control of plants with unmodeled dynamics. The derivation makes use of information available about the unmodeled dynamics both a priori as well as during the adaptation process, so as to stabilize the adaptive loop and at the same time overcome the conservativeness and performance limitations of fixed-dead zone adaptive or fixed gain controllers.

  5. Sleep Strategies of Night-Shift Nurses on Days Off: Which Ones are Most Adaptive?

    PubMed Central

    Petrov, Megan E.; Clark, C. Brendan; Molzof, Hylton E.; Johnson, Russell L.; Cropsey, Karen L.; Gamble, Karen L.

    2014-01-01

    Objectives: To determine the off-shift sleep strategies of bi-ethnic night-shift nurses, the relationship between these sleep strategies and adaptation to shift work, and identify the participant-level characteristics associated with a given sleep strategy. Methods: African-American and non-Hispanic White female, night-shift nurses from an academic hospital were recruited to complete a survey on sleep–wake patterns (n = 213). Participants completed the standard shiftwork index and the biological clocks questionnaire to determine sleep strategies and adaptation to night-shift work. In addition, chronotype was determined quantitatively with a modified version of the Munich ChronoType Questionnaire. Most participants worked ~3 consecutive 12-h night-shifts followed by several days off. Results: Five sleep strategies used on days off were identified: (a) night stay, (b) nap proxy, (c) switch sleeper, (d) no sleep, and (e) incomplete switcher. Nap proxy and no sleep types were associated with poorer adaptation to night-shift work. The switch sleeper and incomplete switcher types were identified as more adaptive strategies that were associated with less sleep disturbance, a later chronotype, and less cardiovascular problems. Conclusion: Behavioral sleep strategies are related to adaptation to a typical night-shift schedule among hospital nurses. Nurses are crucial to the safety and well-being of their patients. Therefore, adoption of more adaptive sleep strategies may reduce sleep/wake dysregulation in this population, and improve cardiovascular outcomes. PMID:25566182

  6. State of the art in adaptive control of robotic systems

    NASA Technical Reports Server (NTRS)

    Tosunoglu, Sabri; Tesar, Delbert

    1988-01-01

    An up-to-date assessment of adaptive control technology as applied to robotics is presented. Although the field is relatively new and does not yet represent a mature discipline, considerable attention for the design of sophisticated robot controllers has occured. In this presentation, adaptive control methods are divided into model reference adaptive systems and self-tuning regulators, with further definition of various approaches given in each class. The similarity and distinct features of the designed controllers are delineated and tabulated to enhance comparative review.

  7. Global adaptive control for uncertain nonaffine nonlinear hysteretic systems.

    PubMed

    Liu, Yong-Hua; Huang, Liangpei; Xiao, Dongming; Guo, Yong

    2015-09-01

    In this paper, the global output tracking is investigated for a class of uncertain nonlinear hysteretic systems with nonaffine structures. By combining the solution properties of the hysteresis model with the novel backstepping approach, a robust adaptive control algorithm is developed without constructing a hysteresis inverse. The proposed control scheme is further modified to tackle the bounded disturbances by adaptively estimating their bounds. It is rigorously proven that the designed adaptive controllers can guarantee global stability of the closed-loop system. Two numerical examples are provided to show the effectiveness of the proposed control schemes.

  8. Control of suspended low-gravity simulation system based on self-adaptive fuzzy PID

    NASA Astrophysics Data System (ADS)

    Chen, Zhigang; Qu, Jiangang

    2017-09-01

    In this paper, an active suspended low-gravity simulation system is proposed to follow the vertical motion of the spacecraft. Firstly, working principle and mathematical model of the low-gravity simulation system are shown. In order to establish the balance process and suppress the strong position interference of the system, the idea of self-adaptive fuzzy PID control strategy is proposed. It combines the PID controller with a fuzzy controll strategy, the control system can be automatically adjusted by changing the proportional parameter, integral parameter and differential parameter of the controller in real-time. At last, we use the Simulink tools to verify the performance of the controller. The results show that the system can reach balanced state quickly without overshoot and oscillation by the method of the self-adaptive fuzzy PID, and follow the speed of 3m/s, while simulation degree of accuracy of system can reach to 95.9% or more.

  9. Hormesis and adaptive cellular control systems

    EPA Science Inventory

    Hormetic dose response occurs for many endpoints associated with exposures of biological organisms to environmental stressors. Cell-based U- or inverted U-shaped responses may derive from common processes involved in activation of adaptive responses required to protect cells from...

  10. Adaptive P300 based control system

    PubMed Central

    Jin, Jing; Allison, Brendan Z.; Sellers, Eric W.; Brunner, Clemens; Horki, Petar; Wang, Xingyu; Neuper, Christa

    2015-01-01

    An adaptive P300 brain-computer interface (BCI) using a 12 × 7 matrix explored new paradigms to improve bit rate and accuracy. During online use, the system adaptively selects the number of flashes to average. Five different flash patterns were tested. The 19-flash paradigm represents the typical row/column presentation (i.e., 12 columns and 7 rows). The 9- and 14-flash A & B paradigms present all items of the 12 × 7 matrix three times using either nine or 14 flashes (instead of 19), decreasing the amount of time to present stimuli. Compared to 9-flash A, 9-flash B decreased the likelihood that neighboring items would flash when the target was not flashing, thereby reducing interference from items adjacent to targets. 14-flash A also reduced adjacent item interference and 14-flash B additionally eliminated successive (double) flashes of the same item. Results showed that accuracy and bit rate of the adaptive system were higher than the non-adaptive system. In addition, 9- and 14-flash B produced significantly higher performance than their respective A conditions. The results also show the trend that the 14-flash B paradigm was better than the 19-flash pattern for naïve users. PMID:21474877

  11. Hormesis and adaptive cellular control systems

    EPA Science Inventory

    Hormetic dose response occurs for many endpoints associated with exposures of biological organisms to environmental stressors. Cell-based U- or inverted U-shaped responses may derive from common processes involved in activation of adaptive responses required to protect cells from...

  12. Advanced control strategies for fluidized bed dryers

    SciTech Connect

    Siettos, C.I.; Kiranoudis, C.T.; Bafas, G.V.

    1999-11-01

    Generating the best possible control strategy comprises a necessity for industrial processes, by virtue of product quality, cost reduction and design simplicity. Three different control approaches, namely an Input-Output linearizing, a fuzzy logic and a PID controller, are evaluated for the control of a fluidized bed dryer, a typical non-linear drying process of wide applicability. Based on several closed loop characteristics such as settling times, maximum overshoots and dynamic performance criteria such as IAE, ISE and ITAE, it is shown that the Input-Output linearizing and the fuzzy logic controller exhibit a better performance compared to the PID controller tuned optimally with respect to IAE, for a wide range of disturbances; yet, the relevant advantage of the fuzzy logic over the conventional nonlinear controller issues upon its design simplicity. Typical load rejection and set-point tracking examples are given to illustrate the effectiveness of the proposed approach.

  13. Projection Operator: A Step Towards Certification of Adaptive Controllers

    NASA Technical Reports Server (NTRS)

    Larchev, Gregory V.; Campbell, Stefan F.; Kaneshige, John T.

    2010-01-01

    One of the major barriers to wider use of adaptive controllers in commercial aviation is the lack of appropriate certification procedures. In order to be certified by the Federal Aviation Administration (FAA), an aircraft controller is expected to meet a set of guidelines on functionality and reliability while not negatively impacting other systems or safety of aircraft operations. Due to their inherent time-variant and non-linear behavior, adaptive controllers cannot be certified via the metrics used for linear conventional controllers, such as gain and phase margin. Projection Operator is a robustness augmentation technique that bounds the output of a non-linear adaptive controller while conforming to the Lyapunov stability rules. It can also be used to limit the control authority of the adaptive component so that the said control authority can be arbitrarily close to that of a linear controller. In this paper we will present the results of applying the Projection Operator to a Model-Reference Adaptive Controller (MRAC), varying the amount of control authority, and comparing controller s performance and stability characteristics with those of a linear controller. We will also show how adjusting Projection Operator parameters can make it easier for the controller to satisfy the certification guidelines by enabling a tradeoff between controller s performance and robustness.

  14. A robust adaptive nonlinear fault-tolerant controller via norm estimation for reusable launch vehicles

    NASA Astrophysics Data System (ADS)

    Hu, Chaofang; Gao, Zhifei; Ren, Yanli; Liu, Yunbing

    2016-11-01

    In this paper, a reusable launch vehicle (RLV) attitude control problem with actuator faults is addressed via the robust adaptive nonlinear fault-tolerant control (FTC) with norm estimation. Firstly, the accurate tracking task of attitude angles in the presence of parameter uncertainties and external disturbances is considered. A fault-free controller is proposed using dynamic surface control (DSC) combined with fuzzy adaptive approach. Furthermore, the minimal learning parameter strategy via norm estimation technique is introduced to reduce the multi-parameter adaptive computation burden of fuzzy approximation of the lump uncertainties. Secondly, a compensation controller is designed to handle the partial loss fault of actuator effectiveness. The unknown maximum eigenvalue of actuator efficiency loss factors is estimated online. Moreover, stability analysis guarantees that all signals of the closed-loop control system are semi-global uniformly ultimately bounded. Finally, illustrative simulations show the effectiveness of the proposed method.

  15. Experimental results on discrete-time nonlinear adaptive tracking control of a flexible-link manipulator.

    PubMed

    Rokui, M R; Khorasani, K

    2000-01-01

    The aim of this paper is to develop and implement a nonlinear adaptive control scheme for a single-link flexible manipulator. The controller is designed based on a discrete-time nonlinear model of the arm. The model is derived by using the forward difference method (Euler approximation). The output redefinition concept is then used so that the associated zero dynamics corresponding to the new output is guaranteed to be exponentially stable. An indirect adaptive linearizing controller is developed for the resulting minimum phase system where the "payload mass" is assumed to be unknown but its upper bound is assumed to be known a priori. The performance of the adaptively controlled closed-loop system is investigated by both numerical simulations and experimental results. The proposed controller is also compared experimentally with those of nonadaptive feedback linearization and conventional proportional derivative (PD) control strategies.

  16. A Pollution Control Strategy Game: Costs of Control Policies.

    ERIC Educational Resources Information Center

    Bierma, Thomas J.; Walbert, Mark S.

    1987-01-01

    Describes an interactive classroom game designed to enhance student understanding of air pollution control strategies. Discusses the game's focus on the differences in compliance costs that can occur between the three principal control approaches of emission limits, emission permits, and emission taxes. (TW)

  17. A Pollution Control Strategy Game: Costs of Control Policies.

    ERIC Educational Resources Information Center

    Bierma, Thomas J.; Walbert, Mark S.

    1987-01-01

    Describes an interactive classroom game designed to enhance student understanding of air pollution control strategies. Discusses the game's focus on the differences in compliance costs that can occur between the three principal control approaches of emission limits, emission permits, and emission taxes. (TW)

  18. Adaptive Fuzzy Control of a Direct Drive Motor

    NASA Technical Reports Server (NTRS)

    Medina, E.; Kim, Y. T.; Akbaradeh-T., M. -R.

    1997-01-01

    This paper presents a state feedback adaptive control method for position and velocity control of a direct drive motor. The proposed control scheme allows for integrating heuristic knowledge with mathematical knowledge of a system. It performs well even when mathematical model of the system is poorly understood. The controller consists of an adaptive fuzzy controller and a supervisory controller. The supervisory controller requires only knowledge of the upper bound and lower bound of the system parameters. The fuzzy controller is based on fuzzy basis functions and states of the system. The adaptation law is derived based on the Lyapunov function which ensures that the state of the system asymptotically approaches zero. The proposed controller is applied to a direct drive motor with payload and parameter uncertainty, and the effectiveness is verified by simulation results.

  19. Adaptive Fuzzy Control of a Direct Drive Motor: Experimental Aspects

    NASA Technical Reports Server (NTRS)

    Medina, E.; Akbarzadeh-T, M.-R.; Kim, Y. T.

    1998-01-01

    This paper presents a state feedback adaptive control method for position and velocity control of a direct drive motor. The proposed control scheme allows for integrating heuristic knowledge with mathematical knowledge of a system. It performs well even when mathematical model of the system is poorly understood. The controller consists of an adaptive fuzzy controller and a supervisory controller. The supervisory controller requires only knowledge of the upper bound and lower bound of the system parameters. The fuzzy controller is based on fuzzy basis functions and states of the system. The adaptation law is derived based on the Lyapunov function which ensures that the state of the system asymptotically approaches zero. The proposed controller is applied to a direct drive motor with payload and parameter uncertainty, and the effectiveness is experimentally verified. The real-time performance is compared with simulation results.

  20. An adaptive control scheme for a flexible manipulator

    NASA Technical Reports Server (NTRS)

    Yang, T. C.; Yang, J. C. S.; Kudva, P.

    1987-01-01

    The problem of controlling a single link flexible manipulator is considered. A self-tuning adaptive control scheme is proposed which consists of a least squares on-line parameter identification of an equivalent linear model followed by a tuning of the gains of a pole placement controller using the parameter estimates. Since the initial parameter values for this model are assumed unknown, the use of arbitrarily chosen initial parameter estimates in the adaptive controller would result in undesirable transient effects. Hence, the initial stage control is carried out with a PID controller. Once the identified parameters have converged, control is transferred to the adaptive controller. Naturally, the relevant issues in this scheme are tests for parameter convergence and minimization of overshoots during control switch-over. To demonstrate the effectiveness of the proposed scheme, simulation results are presented with an analytical nonlinear dynamic model of a single link flexible manipulator.

  1. Adaptive Flight Control Design with Optimal Control Modification on an F-18 Aircraft Model

    NASA Technical Reports Server (NTRS)

    Burken, John J.; Nguyen, Nhan T.; Griffin, Brian J.

    2010-01-01

    In the presence of large uncertainties, a control system needs to be able to adapt rapidly to regain performance. Fast adaptation is referred to as 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 the 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 robustness. A damping term (v) is added in the modification to increase damping as needed. Simulations were conducted on a damaged F-18 aircraft (McDonnell Douglas, now The Boeing Company, Chicago, Illinois) with both the standard baseline dynamic inversion controller and the adaptive optimal control modification technique. The results demonstrate the effectiveness of the proposed modification in tracking a reference model.

  2. Complete synchronization of uncertain chaotic systems via a single proportional adaptive controller: A comparative study

    SciTech Connect

    Ahmad, Israr Saaban, Azizan Bin Ibrahim, Adyda Binti; Shahzad, Mohammad

    2015-12-11

    This paper addresses a comparative computational study on the synchronization quality, cost and converging speed for two pairs of identical chaotic and hyperchaotic systems with unknown time-varying parameters. It is assumed that the unknown time-varying parameters are bounded. Based on the Lyapunov stability theory and using the adaptive control method, a single proportional controller is proposed to achieve the goal of complete synchronizations. Accordingly, appropriate adaptive laws are designed to identify the unknown time-varying parameters. The designed control strategy is easy to implement in practice. Numerical simulations results are provided to verify the effectiveness of the proposed synchronization scheme.

  3. Situational Strategies for Self-Control.

    PubMed

    Duckworth, Angela L; Gendler, Tamar Szabó; Gross, James J

    2016-01-01

    Exercising self-control is often difficult, whether declining a drink in order to drive home safely, passing on the chocolate cake to stay on a diet, or ignoring text messages to finish reading an important paper. But enacting self-control is not always difficult, particularly when it takes the form of proactively choosing or changing situations in ways that weaken undesirable impulses or potentiate desirable ones. Examples of situational self-control include the partygoer who chooses a seat far from where drinks are being poured, the dieter who asks the waiter not to bring around the dessert cart, and the student who goes to the library without a cell phone. Using the process model of self-control, we argue that the full range of self-control strategies can be organized by considering the timeline of the developing tempting impulse. Because impulses tend to grow stronger over time, situational self-control strategies-which can nip a tempting impulse in the bud-may be especially effective in preventing undesirable action. Ironically, we may underappreciate situational self-control for the same reason it is so effective-namely, that by manipulating our circumstances to advantage, we are often able to minimize the in-the-moment experience of intrapsychic struggle typically associated with exercising self-control.

  4. Generalized projective synchronization of the fractional-order chaotic system using adaptive fuzzy sliding mode control

    NASA Astrophysics Data System (ADS)

    Wang, Li-Ming; Tang, Yong-Guang; Chai, Yong-Quan; Wu, Feng

    2014-10-01

    An adaptive fuzzy sliding mode strategy is developed for the generalized projective synchronization of a fractional-order chaotic system, where the slave system is not necessarily known in advance. Based on the designed adaptive update laws and the linear feedback method, the adaptive fuzzy sliding controllers are proposed via the fuzzy design, and the strength of the designed controllers can be adaptively adjusted according to the external disturbances. Based on the Lyapunov stability theorem, the stability and the robustness of the controlled system are proved theoretically. Numerical simulations further support the theoretical results of the paper and demonstrate the efficiency of the proposed method. Moreover, it is revealed that the proposed method allows us to manipulate arbitrarily the response dynamics of the slave system by adjusting the desired scaling factor λi and the desired translating factor ηi, which may be used in a channel-independent chaotic secure communication.

  5. Managing Air Quality - Control Strategies to Achieve Air Pollution Reduction

    EPA Pesticide Factsheets

    Considerations in designing an effective control strategy related to air quality, controlling pollution sources, need for regional or national controls, steps to developing a control strategy, and additional EPA resources.

  6. Stabilizing Spatially-Structured Populations through Adaptive Limiter Control

    PubMed Central

    Sah, Pratha; Dey, Sutirth

    2014-01-01

    Stabilizing the dynamics of complex, non-linear systems is a major concern across several scientific disciplines including ecology and conservation biology. Unfortunately, most methods proposed to reduce the fluctuations in chaotic systems are not applicable to real, biological populations. This is because such methods typically require detailed knowledge of system specific parameters and the ability to manipulate them in real time; conditions often not met by most real populations. Moreover, real populations are often noisy and extinction-prone, which can sometimes render such methods ineffective. Here, we investigate a control strategy, which works by perturbing the population size, and is robust to reasonable amounts of noise and extinction probability. This strategy, called the Adaptive Limiter Control (ALC), has been previously shown to increase constancy and persistence of laboratory populations and metapopulations of Drosophila melanogaster. Here, we present a detailed numerical investigation of the effects of ALC on the fluctuations and persistence of metapopulations. We show that at high migration rates, application of ALC does not require a priori information about the population growth rates. We also show that ALC can stabilize metapopulations even when applied to as low as one-tenth of the total number of subpopulations. Moreover, ALC is effective even when the subpopulations have high extinction rates: conditions under which another control algorithm had previously failed to attain stability. Importantly, ALC not only reduces the fluctuation in metapopulation sizes, but also the global extinction probability. Finally, the method is robust to moderate levels of noise in the dynamics and the carrying capacity of the environment. These results, coupled with our earlier empirical findings, establish ALC to be a strong candidate for stabilizing real biological metapopulations. PMID:25153073

  7. Design of Low Complexity Model Reference Adaptive Controllers

    NASA Technical Reports Server (NTRS)

    Hanson, Curt; Schaefer, Jacob; Johnson, Marcus; Nguyen, Nhan

    2012-01-01

    Flight research experiments have demonstrated that adaptive flight controls can be an effective technology for improving aircraft safety in the event of failures or damage. However, the nonlinear, timevarying nature of adaptive algorithms continues to challenge traditional methods for the verification and validation testing of safety-critical flight control systems. Increasingly complex adaptive control theories and designs are emerging, but only make testing challenges more difficult. A potential first step toward the acceptance of adaptive flight controllers by aircraft manufacturers, operators, and certification authorities is a very simple design that operates as an augmentation to a non-adaptive baseline controller. Three such controllers were developed as part of a National Aeronautics and Space Administration flight research experiment to determine the appropriate level of complexity required to restore acceptable handling qualities to an aircraft that has suffered failures or damage. The controllers consist of the same basic design, but incorporate incrementally-increasing levels of complexity. Derivations of the controllers and their adaptive parameter update laws are presented along with details of the controllers implementations.

  8. Discrete-time adaptive control of robot manipulators

    NASA Technical Reports Server (NTRS)

    Tarokh, M.

    1989-01-01

    A discrete-time model reference adaptive control scheme is developed for trajectory tracking of robot manipulators. Hyperstability theory is utilized to derive the adaptation laws for the controller gain matrices. It is shown that asymptotic trajectory tracking is achieved despite gross robot parameter variation and uncertainties. The method offers considerable design flexibility and enables the designer to improve the performance of the control system by adjusting free design parameters. The discrete-time adaptation algorithm is extremely simple and is therefore suitable for real-time implementation.

  9. Adaptive Force And Position Control For Robots

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun

    1989-01-01

    Control system causes end effector of robot manipulator to follow prescribed trajectory and applies desired force or torque to object manipulating or in contact. Characterized by hybrid control architecture, where positions and orientations along unconstrained coordinate axes controlled by position-control subsystem, while forces and torques along constrained coordinate axes controlled by force-control subsystem. Compensates for dynamic cross-coupling between force-and position-control loops and does not require knowledge of complicated model of dynamics of manipulator and environment.

  10. Social Networks-Based Adaptive Pairing Strategy for Cooperative Learning

    ERIC Educational Resources Information Center

    Chuang, Po-Jen; Chiang, Ming-Chao; Yang, Chu-Sing; Tsai, Chun-Wei

    2012-01-01

    In this paper, we propose a grouping strategy to enhance the learning and testing results of students, called Pairing Strategy (PS). The proposed method stems from the need of interactivity and the desire of cooperation in cooperative learning. Based on the social networks of students, PS provides members of the groups to learn from or mimic…

  11. When Easy Comes Hard: The Development of Adaptive Strategy Selection

    ERIC Educational Resources Information Center

    Mata, Rui; von Helversen, Bettina; Rieskamp, Jorg

    2011-01-01

    Can children learn to select the right strategy for a given problem? In one experiment, 9- to 10-year-olds (N = 50), 11- to 12-year-olds (N = 50), and adults (N = 50) made probabilistic inferences. Participants encountered environments favoring either an information-intensive strategy that integrates all available information or an…

  12. Identification and dual adaptive control of a turbojet engine

    NASA Technical Reports Server (NTRS)

    Merrill, W.; Leininger, G.

    1979-01-01

    The objective of this paper is to utilize the design methods of modern control theory to realize a dual-adaptive feedback control unit for a highly nonlinear single spool airbreathing turbojet engine. Using a very detailed and accurate simulation of the nonlinear engine as the data source, linear operating point models of unspecified dimension are identified. Feedback control laws are designed at each operating point for a prespecified set of sampling rates using sampled-data output regulator theory. The control system sampling rate is determined by an adaptive sampling algorithm in correspondence with turbojet engine performance. The result is a dual-adaptive control law that is functionally dependent upon the sampling rate selected and environmental operating conditions. Simulation transients demonstrate the utility of the dual-adaptive design to improve on-board computer utilization while maintaining acceptable levels of engine performance.

  13. Parameter Estimation for a Hybrid Adaptive Flight Controller

    NASA Technical Reports Server (NTRS)

    Campbell, Stefan F.; Nguyen, Nhan T.; Kaneshige, John; Krishnakumar, Kalmanje

    2009-01-01

    This paper expands on the hybrid control architecture developed at the NASA Ames Research Center by addressing issues related to indirect adaptation using the recursive least squares (RLS) algorithm. Specifically, the hybrid control architecture is an adaptive flight controller that features both direct and indirect adaptation techniques. This paper will focus almost exclusively on the modifications necessary to achieve quality indirect adaptive control. Additionally this paper will present results that, using a full non -linear aircraft model, demonstrate the effectiveness of the hybrid control architecture given drastic changes in an aircraft s dynamics. Throughout the development of this topic, a thorough discussion of the RLS algorithm as a system identification technique will be provided along with results from seven well-known modifications to the popular RLS algorithm.

  14. Disturbance Accommodating Adaptive Control with Application to Wind Turbines

    NASA Technical Reports Server (NTRS)

    Frost, Susan

    2012-01-01

    Adaptive control techniques are well suited to applications that have unknown modeling parameters and poorly known operating conditions. Many physical systems experience external disturbances that are persistent or continually recurring. Flexible structures and systems with compliance between components often form a class of systems that fail to meet standard requirements for adaptive control. For these classes of systems, a residual mode filter can restore the ability of the adaptive controller to perform in a stable manner. New theory will be presented that enables adaptive control with accommodation of persistent disturbances using residual mode filters. After a short introduction to some of the control challenges of large utility-scale wind turbines, this theory will be applied to a high-fidelity simulation of a wind turbine.

  15. 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.

  16. Adaptive optimization and control using neural networks

    SciTech Connect

    Mead, W.C.; Brown, S.K.; Jones, R.D.; Bowling, P.S.; Barnes, C.W.

    1993-10-22

    Recent work has demonstrated the ability of neural-network-based controllers to optimize and control machines with complex, non-linear, relatively unknown control spaces. We present a brief overview of neural networks via a taxonomy illustrating some capabilities of different kinds of neural networks. We present some successful control examples, particularly the optimization and control of a small-angle negative ion source.

  17. On Adaptive Extended Different Life Cycle of Product Design Strategy

    NASA Astrophysics Data System (ADS)

    Wenwen, Jiang; Zhibin, Xie

    The article uses research ways of following the whole lifespan of product and enterprise's development course to research strategy of company's product design and development. It announces enterprises of different nature, enterprises at different developing stage will adopt different mode strategy. It also announces close causality between development course of company and central technology and product. The result indicated in different developing stages such as company development period, crisis predicament period, lasting steadies period, improving by payback period, issues steadies secondary period, declining go and live period, enterprise should pursue different mode product tactics of research and development such as shrinking strategy, consolidating strategy, innovation keeping forging ahead strategy. Enterprise should break regular management mode to introduce different research and development mode to promote enterprise's competitiveness effectively.

  18. Dynamics and Adaptive Control for Stability Recovery of Damaged Aircraft

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan; Krishnakumar, Kalmanje; Kaneshige, John; Nespeca, Pascal

    2006-01-01

    This paper presents a recent study of a damaged generic transport model as part of a NASA research project to investigate adaptive control methods for stability recovery of damaged aircraft operating in off-nominal flight conditions under damage and or failures. Aerodynamic modeling of damage effects is performed using an aerodynamic code to assess changes in the stability and control derivatives of a generic transport aircraft. Certain types of damage such as damage to one of the wings or horizontal stabilizers can cause the aircraft to become asymmetric, thus resulting in a coupling between the longitudinal and lateral motions. Flight dynamics for a general asymmetric aircraft is derived to account for changes in the center of gravity that can compromise the stability of the damaged aircraft. An iterative trim analysis for the translational motion is developed to refine the trim procedure by accounting for the effects of the control surface deflection. A hybrid direct-indirect neural network, adaptive flight control is proposed as an adaptive law for stabilizing the rotational motion of the damaged aircraft. The indirect adaptation is designed to estimate the plant dynamics of the damaged aircraft in conjunction with the direct adaptation that computes the control augmentation. Two approaches are presented 1) an adaptive law derived from the Lyapunov stability theory to ensure that the signals are bounded, and 2) a recursive least-square method for parameter identification. A hardware-in-the-loop simulation is conducted and demonstrates the effectiveness of the direct neural network adaptive flight control in the stability recovery of the damaged aircraft. A preliminary simulation of the hybrid adaptive flight control has been performed and initial data have shown the effectiveness of the proposed hybrid approach. Future work will include further investigations and high-fidelity simulations of the proposed hybrid adaptive Bight control approach.

  19. Adaptive tracking control for a class of uncertain chaotic systems

    NASA Astrophysics Data System (ADS)

    Chen, Feng-Xiang; Wang, Wei; Zhang, Wei-Dong

    2007-09-01

    The paper is concerned with adaptive tracking problem for a class of chaotic system with time-varying uncertainty, but bounded by norm polynomial. Based on adaptive technique, it proposes a novel controller to asymptotically track the arbitrary desired bounded trajectory. Simulation on the Rossler chaotic system is performed and the result verifies the effectiveness of the proposed method.

  20. Adaptive fuzzy predictive sliding control of uncertain nonlinear systems with bound-known input delay.

    PubMed

    Khazaee, Mostafa; Markazi, Amir H D; Omidi, Ehsan

    2015-11-01

    In this paper, a new Adaptive Fuzzy Predictive Sliding Mode Control (AFP-SMC) is presented for nonlinear systems with uncertain dynamics and unknown input delay. The control unit consists of a fuzzy inference system to approximate the ideal linearization control, together with a switching strategy to compensate for the estimation errors. Also, an adaptive fuzzy predictor is used to estimate the future values of the system states to compensate for the time delay. The adaptation laws are used to tune the controller and predictor parameters, which guarantee the stability based on a Lyapunov-Krasovskii functional. To evaluate the method effectiveness, the simulation and experiment on an overhead crane system are presented. According to the obtained results, AFP-SMC can effectively control the uncertain nonlinear systems, subject to input delays of known bound. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.