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Sample records for active control approach

  1. A new approach of active compliance control via fuzzy logic control for multifingered robot hand

    NASA Astrophysics Data System (ADS)

    Jamil, M. F. A.; Jalani, J.; Ahmad, A.

    2016-07-01

    Safety is a vital issue in Human-Robot Interaction (HRI). In order to guarantee safety in HRI, a model reference impedance control can be a very useful approach introducing a compliant control. In particular, this paper establishes a fuzzy logic compliance control (i.e. active compliance control) to reduce impact and forces during physical interaction between humans/objects and robots. Exploiting a virtual mass-spring-damper system allows us to determine a desired compliant level by understanding the behavior of the model reference impedance control. The performance of fuzzy logic compliant control is tested in simulation for a robotic hand known as the RED Hand. The results show that the fuzzy logic is a feasible control approach, particularly to control position and to provide compliant control. In addition, the fuzzy logic control allows us to simplify the controller design process (i.e. avoid complex computation) when dealing with nonlinearities and uncertainties.

  2. Semi-active controller design for vibration suppression and energy harvesting via LMI approach

    NASA Astrophysics Data System (ADS)

    Liu, Yilun; Lin, Chi-Chang; Zuo, Lei

    2014-04-01

    The vibration control plays an important role in energy harvesting systems. Compared to the active control, semi-active control is a more preferred alternative for practical use. Many different semi-active control strategies have been developed, among which LQ-clip, Skyhook and model predictive control are the most popular strategies in literatures. In this paper, a different control strategy that designs semi-active controller via LMI approach is proposed. Different from clipping the control input after controller construction like most existing control methods, the proposed method fulfills the semi-active control input feasibility constraints before the controller construction. The methodology is developed through LMI approach which leads to a stabilizing linear controller to ensure semi-active constraint and the pre-designed performance. An illustrative example, vibration control system of a tall building, is presented to show the efficiency of the method and validate the new approach.

  3. Artificial hydrogenase: biomimetic approaches controlling active molecular catalysts.

    PubMed

    Onoda, Akira; Hayashi, Takashi

    2015-04-01

    Hydrogenase catalyses reversible transformation of H2 to H(+) using an active site which includes an iron or nickel atom. Synthetic model complexes and molecular catalysts inspired by nature have unveiled the structural and functional basis of the active site with remarkable accuracy and this has led to the discovery of active synthetic catalysts. To further improve the activity of such molecular catalysts, both the first and outer coordination spheres should be well-organized and harmonized for an efficient shuttling of H(+), electrons, and H2. This article reviews recent advances in the design and catalytic properties of artificial enzymes that mimic the hydrogenase active site and the outer coordination sphere in combination with a peptide or protein scaffold.

  4. The active disturbance rejection control approach to stabilisation of coupled heat and ODE system subject to boundary control matched disturbance

    NASA Astrophysics Data System (ADS)

    Guo, Bao-Zhu; Liu, Jun-Jun; AL-Fhaid, A. S.; Younas, Arshad Mahmood M.; Asiri, Asim

    2015-08-01

    We consider stabilisation for a linear ordinary differential equation system with input dynamics governed by a heat equation, subject to boundary control matched disturbance. The active disturbance rejection control approach is applied to estimate, in real time, the disturbance with both constant high gain and time-varying high gain. The disturbance is cancelled in the feedback loop. The closed-loop systems with constant high gain and time-varying high gain are shown, respectively, to be practically stable and asymptotically stable.

  5. Approaches to Adaptive Active Acoustic Noise Control at a Point Using Feedforward Techniques.

    NASA Astrophysics Data System (ADS)

    Zulch, Peter A.

    Active acoustic noise control systems have been of interest since their birth in the 1930's. The principle is to superimpose on an unwanted noise wave shape its inverse with the intention of destructive interference. This work presents two approaches to this idea. The first approach uses a direct design method to develop a controller using an auto-regressive moving-average (ARMA) model that will be used to condition the primary noise to produce the required anti-noise for cancellation. The development of this approach has shown that the stability of the controller relies heavily on a non-minimum phase model of the secondary noise path. For this reason, a second approach, using a controller consisting of two parts was developed. The first part of the controller is designed to cancel broadband noise and the second part is an adaptive controller designed to cancel periodic noise. A simple technique for identifying the parameters of the broadband controller is developed. An ARMA model is used, and it is shown that its stability is improved by prefiltering the test signal with a minimum-phase inverse of the secondary noise channel. The periodic controller uses an estimate of the fundamental frequency to cancel the first few harmonics of periodic noise. A computationally efficient adaptive technique based on least squares is developed for updating the harmonic controller gains at each time step. Experimental results are included for the broadband controller, the harmonic controller, and the combination of the two algorithms. The advantages of using both techniques in conjunction are shown using test cases involving both broadband noise and periodic noise.

  6. An active damping control of robot manipulators with oscillatory bases by singular perturbation approach

    NASA Astrophysics Data System (ADS)

    Lin, J.; Huang, Z. Z.; Huang, P. H.

    2007-07-01

    This paper deals with active damping control problems of robot manipulators with oscillatory bases. A first investigation of two-time scale fuzzy logic controller with vibration stabilizer for such structures has been proposed, where the dynamics of a robotic system is strongly affected by disturbances due to the base oscillation. Under the assumption of two-time scale, its stability and design procedures are presented for a multiple link manipulator with multiple dimension oscillation. The fast-subsystem controller will damp out the vibration of the oscillatory bases using a PD control method. Hence, the slow-subsystem fuzzy logic controller dominates the trajectory tracking. It can be guaranteed the stability of the internal dynamics by adding a boundary-layer correction based on singular perturbations approach. Experimental results have shown that the proposed control model offers several implementation advantages such as reduced effect of overshoot and chattering, smaller steady state error, and a fast convergent rate. The results of this study can be feasible to various mechanical systems, such as mobile robot, gantry cranes, underwater robot, and other dynamic systems mounted on oscillatory bases.

  7. A Novel Topology Link-Controlling Approach for Active Defense of a Node in a Network.

    PubMed

    Li, Jun; Hu, HanPing; Ke, Qiao; Xiong, Naixue

    2017-03-09

    With the rapid development of virtual machine technology and cloud computing, distributed denial of service (DDoS) attacks, or some peak traffic, poses a great threat to the security of the network. In this paper, a novel topology link control technique and mitigation attacks in real-time environments is proposed. Firstly, a non-invasive method of deploying virtual sensors in the nodes is built, which uses the resource manager of each monitored node as a sensor. Secondly, a general topology-controlling approach of resisting the tolerant invasion is proposed. In the proposed approach, a prediction model is constructed by using copula functions for predicting the peak of a resource through another resource. The result of prediction determines whether or not to initiate the active defense. Finally, a minority game with incomplete strategy is employed to suppress attack flows and improve the permeability of the normal flows. The simulation results show that the proposed approach is very effective in protecting nodes.

  8. A Novel Topology Link-Controlling Approach for Active Defense of Nodes in Networks

    PubMed Central

    Li, Jun; Hu, HanPing; Ke, Qiao; Xiong, Naixue

    2017-01-01

    With the rapid development of virtual machine technology and cloud computing, distributed denial of service (DDoS) attacks, or some peak traffic, poses a great threat to the security of the network. In this paper, a novel topology link control technique and mitigation attacks in real-time environments is proposed. Firstly, a non-invasive method of deploying virtual sensors in the nodes is built, which uses the resource manager of each monitored node as a sensor. Secondly, a general topology-controlling approach of resisting the tolerant invasion is proposed. In the proposed approach, a prediction model is constructed by using copula functions for predicting the peak of a resource through another resource. The result of prediction determines whether or not to initiate the active defense. Finally, a minority game with incomplete strategy is employed to suppress attack flows and improve the permeability of the normal flows. The simulation results show that the proposed approach is very effective in protecting nodes. PMID:28282962

  9. Active Referral: An Innovative Approach to Engaging Traditional Healthcare Providers in TB Control in Burkina Faso

    PubMed Central

    Kaboru, Berthollet Bwira

    2013-01-01

    Background and objective: The involvement of traditional healthcare providers (THPs) has been suggested among strategies to increase tuberculosis case detection. Burkina Faso has embarked on such an attempt. This study is a preliminary assessment of that model. Methods: Qualitative data were collected using unstructured key informant interviews with policy makers, group interviews with THPs and health workers, and field visits to THPs. Quantitative data were collected from program reports and the national tuberculosis (TB) control database. Results and analysis: The distribution of tasks among THPs, intermediary organizations and clinicians is appealing, especially the focus on active referral. THPs are offered incentives based on numbers of suspected cases confirmed by health workers at the clinic, based on microscopy results or clinical assessment. The positivity rate was 23% and 9% for 2006 and 2007, respectively. The contribution of the program to national case detection was estimated at 2% for 2006. Because it relied totally on donor funding, the program suffered from irregular disbursements, resulting in periodic decreases in activities and outcomes. Conclusions: The study shows that single interventions require a broader positive policy environment to be sustainable. Even if the active referral approach seems effective in enhancing TB case detection, more complex policy work and direction, domestic financial contribution and additional evidence for cost-effectiveness are needed before the approach can be established as a national policy. PMID:24359717

  10. Active music therapy approach in amyotrophic lateral sclerosis: a randomized-controlled trial.

    PubMed

    Raglio, Alfredo; Giovanazzi, Elena; Pain, Debora; Baiardi, Paola; Imbriani, Chiara; Imbriani, Marcello; Mora, Gabriele

    2016-12-01

    This randomized controlled study assessed the efficacy of active music therapy (AMT) on anxiety, depression, and quality of life in amyotrophic lateral sclerosis (ALS). Communication and relationship during AMT treatment were also evaluated. Thirty patients were assigned randomly to experimental [AMT plus standard of care (SC)] or control (SC) groups. AMT consisted of 12 sessions (three times a week), whereas the SC treatment was based on physical and speech rehabilitation sessions, occupational therapy, and psychological support. ALS Functional Rating Scale-Revised, Hospital Anxiety and Depression Scale, McGill Quality of Life Questionnaire, and Music Therapy Rating Scale were administered to assess functional, psychological, and music therapy outcomes. The AMT group improved significantly in McGill Quality of Life Questionnaire global scores (P=0.035) and showed a positive trend in nonverbal and sonorous-music relationship during the treatment. Further studies involving larger samples in a longer AMT intervention are needed to confirm the effectiveness of this approach in ALS.

  11. Experimental Comparison of two Active Vibration Control Approaches: Velocity Feedback and Negative Capacitance Shunt Damping

    NASA Technical Reports Server (NTRS)

    Beck, Benjamin; Schiller, Noah

    2013-01-01

    This paper outlines a direct, experimental comparison between two established active vibration control techniques. Active vibration control methods, many of which rely upon piezoelectric patches as actuators and/or sensors, have been widely studied, showing many advantages over passive techniques. However, few direct comparisons between different active vibration control methods have been made to determine the performance benefit of one method over another. For the comparison here, the first control method, velocity feedback, is implemented using four accelerometers that act as sensors along with an analog control circuit which drives a piezoelectric actuator. The second method, negative capacitance shunt damping, consists of a basic analog circuit which utilizes a single piezoelectric patch as both a sensor and actuator. Both of these control methods are implemented individually using the same piezoelectric actuator attached to a clamped Plexiglas window. To assess the performance of each control method, the spatially averaged velocity of the window is compared to an uncontrolled response.

  12. An Investigation of Adaptive Signal Processing Approaches to Active Combustion Control

    DTIC Science & Technology

    2001-06-01

    stabilizing control using an adaptive feedback architecture. As discussed by Annaswamy et al. (1998), previous researchers have not been able to...accurately represents the dynamics of the limit cycling system and can ultimately be used for stabilizing control . System Identification The approach to...achieve stabilizing control . The first is easily identifiable as a feedback loop instability (see Equation 4), whereas the second is less well-defined as a

  13. Generalized proportional integral control for periodic signals under active disturbance rejection approach.

    PubMed

    Cortés-Romero, John; Ramos, Germán A; Coral-Enriquez, Horacio

    2014-11-01

    Conventional repetitive control has proven to be an effective strategy to reject/track periodic signals with constant frequency; however, it shows poor performance in varying frequency applications. This paper proposes an active disturbance rejection methodology applied to a large class of uncertain flat systems for the tracking and rejection of periodic signals, in which the possibilities of the generalized proportional integral (GPI) observer-based control to address repetitive control problems are studied. In the proposed scheme, model uncertainties and external disturbances are lumped together in a general additive disturbance input that is estimated and rejected on-line. An illustrative case study of mechatronic nature is considered. Experimental results show that the proposed GPI observer-based control successfully rejects periodic disturbances even under varying speed conditions.

  14. [Characteristics of pilot motor activity when different control systems are used during landing approaches].

    PubMed

    Brusnichkina, R I

    1980-01-01

    Complex motor acts of pilots during their professional work were investigated with control information presented in a different manner. Two experimental series were run: in a real flight and in a simulator. Parameters of muscle bioelectric activity, control movements and performance efficiency were used. Differences in the formation of motor acts were shown to depend on the scope and quality of the information presented. During required transfer from one mode to another the structure of working movements and performance efficiency obeyed at large changes in the information necessary for piloting. This was accompanied by an alteration in the developed stereotype of actions, including motor acts.

  15. A Visual Analytics Approach to Structured Data Analysis to Enhance Nonproliferation and Arms Control Verification Activities

    SciTech Connect

    Gillen, David S.

    2014-08-07

    Analysis activities for Nonproliferation and Arms Control verification require the use of many types of data. Tabular structured data, such as Excel spreadsheets and relational databases, have traditionally been used for data mining activities, where specific queries are issued against data to look for matching results. The application of visual analytics tools to structured data enables further exploration of datasets to promote discovery of previously unknown results. This paper discusses the application of a specific visual analytics tool to datasets related to the field of Arms Control and Nonproliferation to promote the use of visual analytics more broadly in this domain. Visual analytics focuses on analytical reasoning facilitated by interactive visual interfaces (Wong and Thomas 2004). It promotes exploratory analysis of data, and complements data mining technologies where known patterns can be mined for. Also with a human in the loop, they can bring in domain knowledge and subject matter expertise. Visual analytics has not widely been applied to this domain. In this paper, we will focus on one type of data: structured data, and show the results of applying a specific visual analytics tool to answer questions in the Arms Control and Nonproliferation domain. We chose to use the T.Rex tool, a visual analytics tool developed at PNNL, which uses a variety of visual exploration patterns to discover relationships in structured datasets, including a facet view, graph view, matrix view, and timeline view. The facet view enables discovery of relationships between categorical information, such as countries and locations. The graph tool visualizes node-link relationship patterns, such as the flow of materials being shipped between parties. The matrix visualization shows highly correlated categories of information. The timeline view shows temporal patterns in data. In this paper, we will use T.Rex with two different datasets to demonstrate how interactive exploration of

  16. An Integrated Observational and Model Synthesis Approach to Examine Dominant Environmental Controls on Active Layer Thickness

    NASA Astrophysics Data System (ADS)

    Atchley, A. L.; Coon, E.; Painter, S. L.; Harp, D. R.; Wilson, C. J.

    2015-12-01

    The active layer thickness (ALT) - the annual maximum depth of soil with above 0°C temperatures - in part determines the volume of carbon-rich stores available for decomposition and therefore potential greenhouse gas release into the atmosphere from Arctic tundra. However, understanding and predicting ALT in polygonal tundra landscapes is difficult due to the complex nature of hydrothermal atmospheric-surface-subsurface interactions in freezing/thawing soil. Simply deconvolving effects of single environmental controls on ALT is not possible with measurements alone as processes act in concert to drive thaw depth formation. Process-rich models of thermal hydrological dynamics, conversely, are a valuable tool for understanding the dominant controls and uncertainties in predicting permafrost conditions. By integrating observational data with known physical relationships to form process-rich models, synthetic experiments can then be used to explore a breadth of environmental conditions encountered and the effect of each environmental attribute may be assessed. Here a process rich thermal hydrology model, The Advanced Terrestrial Simulator, has been created and calibrated using observed data from Barrow, AK. An ensemble of 1D thermal hydrologic models were simulated that span a range of three environmental factors 1) thickness of organic rich soil, 2) snow depth, and 3) soil moisture content, to investigate the role of each factor on ALT. Results show that organic layer thickness acts as a strong insulator and is the dominant control of ALT, but the strength of the effect of organic layer thickness is also dependent on the saturation state. Using the ensemble results, the effect of peat thickness on ALT was then examined on a 2D domain. This work was supported by LANL Laboratory Directed Research and Development Project LDRD201200068DR and by the The Next-Generation Ecosystem Experiments (NGEE Arctic) project. NGEE-Arctic is supported by the Office of Biological and

  17. Active Structural Acoustic Control as an Approach to Acoustic Optimization of Lightweight Structures

    DTIC Science & Technology

    2001-06-01

    appropriate approach based on Statistical Energy Analysis (SEA) would facilitate investigations of the structural behavior at a high modal density. On the way...higher frequency investigations an approach based on the Statistical Energy Analysis (SEA) is recommended to describe the structural dynamic behavior

  18. Active control system trends

    NASA Technical Reports Server (NTRS)

    Yore, E. E.; Gunderson, D. C.

    1976-01-01

    The active control concepts which achieve the benefit of improved mission performance and lower cost and generate system trends towards improved dynamic performance, more integration, and digital fly by wire mechanization are described. Analytical issues and implementation requirements and tools and approaches developed to address the analytical and implementation issues are briefly discussed.

  19. An integrated approach to the optimum design of actively controlled composite wings

    NASA Technical Reports Server (NTRS)

    Livne, E.

    1989-01-01

    The importance of interactions among the various disciplines in airplane wing design has been recognized for quite some time. With the introduction of high gain, high authority control systems and the design of thin, flexible, lightweight composite wings, the integrated treatment of control systems, flight mechanics and dynamic aeroelasticity became a necessity. A research program is underway now aimed at extending structural synthesis concepts and methods to the integrated synthesis of lifting surfaces, spanning the disciplines of structures, aerodynamics and control for both analysis and design. Mathematical modeling techniques are carefully selected to be accurate enough for preliminary design purposes of the complicated, built-up lifting surfaces of real aircraft with their multiple design criteria and tight constraints. The presentation opens with some observations on the multidisciplinary nature of wing design. A brief review of some available state of the art practical wing optimization programs and a brief review of current research effort in the field serve to illuminate the motivation and support the direction taken in our research. The goals of this research effort are presented, followed by a description of the analysis and behavior sensitivity techniques used. The presentation concludes with a status report and some forecast of upcoming progress.

  20. Increasing resource allocation and research into tobacco control activities: a comprehensive approach including primary prevention, treatment and brief intervention.

    PubMed

    Richmond, R

    1993-01-01

    The range of tobacco control activities should be viewed as essential parts of a complex multi-component puzzle. Intervention strategies designed to address tobacco control should be comprehensive and include both primary and secondary prevention activities and be multi-faceted and capable of bringing about change at both the individual and broader social and cultural levels. In this paper I argue for a mutually inclusive framework in which the various components contribute in important and different ways. I examine the prevalence of smoking and identify the high risk groups, then I examine the range of available strategies and present the evidence for their success. I discuss the primary prevention approaches such as warning labels, taxes, price increases, workplace bans, education in schools, mass media and self-help materials, as well as brief interventions and treatment strategies which are conducted at the worksite, general practice and specialized cessation clinics. The areas for future research are delineated for increased resource allocation and include: the best ways to disseminate brief interventions to smokers, methods to motivate smokers; training of health professionals to deliver brief interventions; enhancing quitting and access to existing treatment resources among specific disadvantaged minority groups, e.g. migrants, unemployed youth, the effect on smoking prevalence of warning labels on cigarette packets and price rises on cigarettes.

  1. An H-Infinity Approach to Control Synthesis with Load Minimization for the F/A-18 Active Aeroelastic Wing

    NASA Technical Reports Server (NTRS)

    Lind, Rick

    1999-01-01

    The F/A-18 Active Aeroelastic Wing research aircraft will demonstrate technologies related to aeroservoelastic effects such as wing twist and load minimization. This program presents several challenges for control design that are often not considered for traditional aircraft. This paper presents a control design based on H-infinity synthesis that simultaneously considers the multiple objectives associated with handling qualities, actuator limitations, and loads. A point design is presented to demonstrate a controller and the resulting closed-loop properties.

  2. Removal of Intermediate Aromatic Halogenated DBPs by Activated Carbon Adsorption: A New Approach to Controlling Halogenated DBPs in Chlorinated Drinking Water.

    PubMed

    Jiang, Jingyi; Zhang, Xiangru; Zhu, Xiaohu; Li, Yu

    2017-03-21

    During chlorine disinfection of drinking water, chlorine may react with natural organic matter (NOM) and bromide ion in raw water to generate halogenated disinfection byproducts (DBPs). To mitigate adverse effects from DBP exposure, granular activated carbon (GAC) adsorption has been considered as one of the best available technologies for removing NOM (DBP precursor) in drinking water treatment. Recently, we have found that many aromatic halogenated DBPs form in chlorination, and they act as intermediate DBPs to decompose and form commonly known DBPs including trihalomethanes and haloacetic acids. In this work, we proposed a new approach to controlling drinking water halogenated DBPs by GAC adsorption of intermediate aromatic halogenated DBPs during chlorination, rather than by GAC adsorption of NOM prior to chlorination (i.e., traditional approach). Rapid small-scale column tests were used to simulate GAC adsorption in the new and traditional approaches. Significant reductions of aromatic halogenated DBPs were observed in the effluents with the new approach; the removals of total organic halogen, trihalomethanes, and haloacetic acids by the new approach always exceeded those by the traditional approach; and the effluents with the new approach were considerably less developmentally toxic than those with the traditional approach. Our findings indicate that the new approach is substantially more effective in controlling halogenated DBPs than the traditional approach.

  3. Integrated approach for biofouling control.

    PubMed

    Vrouwenvelder, J S; Kruithof, J C; Van Loosdrecht, M C M

    2010-01-01

    Despite extensive research efforts, past and present strategies to control biofouling problems in spiral-wound nanofiltration and reverse osmosis membranes have not been successful under all circumstances. Gaining insight in the biofouling process is a first necessity. Based on recent insights, an overview is given of 12 potential complementary approaches to solve biofouling. Combinations of approaches may be more efficient in biofouling control than a single approach. A single approach must be 100% effective, while in combination each individual approach can be partially effective while the combination is still efficient. An integrated Approach for Biofouling Control (ABC) is proposed, based on three corner stones: (i) equipment design and operation, (ii) biomass growth conditions, and (iii) cleaning agents as a framework to control biofouling. While past and present strategies addressed mainly membranes and microorganisms, i.e. removal or inactivation of biomass, this ABC-approach addresses the total membrane filtration system. It is anticipated that this integral approach will enable a more rational and effective control of biofouling. Although in this stage chemical cleaning and biofouling inhibitor dosage seem unavoidable to control biofouling, it is expected that in future--because of sustainability and costs reasons--membrane systems will be developed without or with minimal need for chemical cleaning and dosing. Three potential scenarios for biofouling control are proposed based on (i) biofouling tolerant spiral wound membrane systems, (ii) capillary membranes, and (iii) phosphate limitation.

  4. Fractional order PID control design for semi-active control of smart base-isolated structures: A multi-objective cuckoo search approach.

    PubMed

    Zamani, Abbas-Ali; Tavakoli, Saeed; Etedali, Sadegh

    2017-03-01

    Fractional order PID (FOPID) controllers are introduced as a general form of classical PID controllers using fractional calculus. As this controller provides good disturbance rejection and is robust against plant uncertainties it is appropriate for the vibration mitigation in structures. In this paper, an FOPID controller is designed to adjust the contact force of piezoelectric friction dampers for semi-active control of base-isolated structures during far-field and near-field earthquake excitations. A multi-objective cuckoo search algorithm is employed to tune the controller parameters. Considering the resulting Pareto optimal front, the best input for the FOPID controller is selected. For seven pairs of earthquakes and nine performance indices, the performance of the proposed controller is compared with those provided by several well-known control techniques. According to the simulation results, the proposed controller performs better than other controllers in terms of simultaneous reduction of the maximum base displacement and story acceleration for various types of earthquakes. Also, it provides acceptable responses in terms of inter-story drifts, root mean square of base displacements and floor acceleration. In addition, the evaluation of robustness for a stiffness uncertainty of ±10% indicates that the proposed controller gives a robust performance against such modeling errors.

  5. Intelligent Control Approaches for UAVs

    NASA Technical Reports Server (NTRS)

    KrisnaKumar, Kalmanje

    2003-01-01

    This talk will present overviews of various intelligent control technologies currently being developed and studied at the NASA Ames Research Center as applicable to Unmanned Aerial Vehicles (UAVs), Mars flyers, and to the next generation of flight controllers for manned aircraft. The approaches being examined include: (a) direct adaptive dynamic inverse controller, (b) adaptive critic-based optimal trajectory generator; (c) optimal allocation technique based on linear programming; (4) immunized maneuvering using autopilot building blocks. These approaches can utilize, but do not require, fault detection and isolation information. Piloted and unmanned simulation studies are performed to examine if the intelligent flight control techniques adequately: 1) match flying qualities of modem fly-by-wire flight controllers under nominal conditions; 2) improve performance under failure conditions when sufficient control authority is available; and 3) achieve intelligent maneuvering capabilities for unmanned vehicles. Results obtained so far will be presented and discussed.

  6. Modeling of a fluid-loaded smart shell structure for active noise and vibration control using a coupled finite element-boundary element approach

    NASA Astrophysics Data System (ADS)

    Ringwelski, S.; Gabbert, U.

    2010-10-01

    A recently developed approach for the simulation and design of a fluid-loaded lightweight structure with surface-mounted piezoelectric actuators and sensors capable of actively reducing the sound radiation and the vibration is presented. The objective of this paper is to describe the theoretical background of the approach in which the FEM is applied to model the actively controlled shell structure. The FEM is also employed to model finite fluid domains around the shell structure as well as fluid domains that are partially or totally bounded by the structure. Boundary elements are used to characterize the unbounded acoustic pressure fields. The approach presented is based on the coupling of piezoelectric and acoustic finite elements with boundary elements. A coupled finite element-boundary element model is derived by introducing coupling conditions at the fluid-fluid and fluid-structure interfaces. Because of the possibility of using piezoelectric patches as actuators and sensors, feedback control algorithms can be implemented directly into the multi-coupled structural-acoustic approach to provide a closed-loop model for the design of active noise and vibration control. In order to demonstrate the applicability of the approach developed, a number of test simulations are carried out and the results are compared with experimental data. As a test case, a box-shaped shell structure with surface-mounted piezoelectric actuators and four sensors and an open rearward end is considered. A comparison between the measured values and those predicted by the coupled finite element-boundary element model shows a good agreement.

  7. Control theory and psychopathology: an integrative approach.

    PubMed

    Mansell, Warren

    2005-06-01

    Perceptual control theory (PCT; Powers, 1973) is presented and adapted as a framework to understand the causes, maintenance, and treatment of psychological disorders. PCT provides dynamic, working models based on the principle that goal-directed activity arises from a hierarchy of negative feedback loops that control perception through control of the environment. The theory proposes that psychological distress arises from the unresolved conflict between goals. The present paper integrates PCT, control theory, and self-regulatory approaches to psychopathology and psychotherapy and recent empirical findings, particularly in the field of cognitive therapy. The approach aims to offer fresh insights into the role of goal conflict, automatic processes, imagery, perceptual distortion, and loss of control in psychological disorders. Implications for psychological therapy are discussed, including an integration of the existing work on the assessment of control profiles and the use of assertive versus yielding modes of control.

  8. Anti-viral drug treatment along with immune activator IL-2: a control-based mathematical approach for HIV infection

    NASA Astrophysics Data System (ADS)

    Nath Chatterjee, Amar; Roy, Priti Kumar

    2012-02-01

    Recent development in antiretroviral treatment against HIV can help AIDS patients to fight against HIV. But the question that whether the disease is to be partially or totally eradicated from HIV infected individuals still remains unsolved. Usually, the most effective treatment for the disease is HAART which can only control the disease progression. But as the immune system becomes weak, the patients can not fight against other diseases. Immune cells are activated and proliferated by IL-2 after the identification of antigen. IL-2 production is impaired in HIV positive patients and intermitted administration of immune activator IL-2 together with HAART which is a more effective treatment to fight against the disease. Thus, its expediency is essential and is yet to be explored. In this article we anticipated a mathematical model of the effect of IL-2 together with RTIs therapy in HIV positive patients. Our analytical as well as numerical study shows that the optimal schedule of treatment for best result is to be obtained by systematic drug therapy. But at the last stage of treatment, the infection level raises again due to minimisation of drug dosage. Thus we study the perfect adherence of the drugs and found out if RTIs are taken with sufficient interval then for fixed interval of IL-2 therapy, certain amount of drug dosages may be able to sustain the immune system at pre-infection stage and the infected CD4+T cells are going towards extinction.

  9. Optical control of antibacterial activity

    NASA Astrophysics Data System (ADS)

    Velema, Willem A.; van der Berg, Jan Pieter; Hansen, Mickel J.; Szymanski, Wiktor; Driessen, Arnold J. M.; Feringa, Ben L.

    2013-11-01

    Bacterial resistance is a major problem in the modern world, stemming in part from the build-up of antibiotics in the environment. Novel molecular approaches that enable an externally triggered increase in antibiotic activity with high spatiotemporal resolution and auto-inactivation are highly desirable. Here we report a responsive, broad-spectrum, antibacterial agent that can be temporally activated with light, whereupon it auto-inactivates on the scale of hours. The use of such a ‘smart’ antibiotic might prevent the build-up of active antimicrobial material in the environment. Reversible optical control over active drug concentration enables us to obtain pharmacodynamic information. Precisely localized control of activity is achieved, allowing the growth of bacteria to be confined to defined patterns, which has potential for the development of treatments that avoid interference with the endogenous microbial population in other parts of the organism.

  10. Angular-velocity control approach for stance-control orthoses.

    PubMed

    Lemaire, Edward D; Goudreau, Louis; Yakimovich, Terris; Kofman, Jonathan

    2009-10-01

    Currently, stance-control knee orthoses require external control mechanisms to control knee flexion during stance and allow free knee motion during the swing phase of gait. A new angular-velocity control approach that uses a rotary-hydraulic device to resist knee flexion when the knee angular velocity passes a preset threshold is presented. This angular-velocity approach for orthotic stance control is based on the premise that knee-flexion angular velocity during a knee-collapse event, such as a stumble or fall, is greater than that during walking. The new hydraulic knee-flexion control device does not require an external control mechanism to switch from free motion to stance control mode. Functional test results demonstrated that the hydraulic angular-velocity activated knee joint provided free knee motion during walking, engaged upon knee collapse, and supported body weight while the end-user recovered to a safe body position. The joint was tested to 51.6 Nm in single loading tests and passed 200,000 repeated loading cycles with a peak load of 88 Nm per cycle. The hydraulic, angular velocity activation approach has potential to improve safety and security for people with lower extremity weakness or when recovering from joint trauma.

  11. Integrated Approach to Malaria Control

    PubMed Central

    Shiff, Clive

    2002-01-01

    Malaria draws global attention in a cyclic manner, with interest and associated financing waxing and waning according to political and humanitarian concerns. Currently we are on an upswing, which should be carefully developed. Malaria parasites have been eliminated from Europe and North America through the use of residual insecticides and manipulation of environmental and ecological characteristics; however, in many tropical and some temperate areas the incidence of disease is increasing dramatically. Much of this increase results from a breakdown of effective control methods developed and implemented in the 1960s, but it has also occurred because of a lack of trained scientists and control specialists who live and work in the areas of endemic infection. Add to this the widespread resistance to the most effective antimalarial drug, chloroquine, developing resistance to other first-line drugs such as sulfadoxine-pyrimethamine, and resistance of certain vector species of mosquito to some of the previously effective insecticides and we have a crisis situation. Vaccine research has proceeded for over 30 years, but as yet there is no effective product, although research continues in many promising areas. A global strategy for malaria control has been accepted, but there are critics who suggest that the single strategy cannot confront the wide range of conditions in which malaria exists and that reliance on chemotherapy without proper control of drug usage and diagnosis will select for drug resistant parasites, thus exacerbating the problem. An integrated approach to control using vector control strategies based on the biology of the mosquito, the epidemiology of the parasite, and human behavior patterns is needed to prevent continued upsurge in malaria in the endemic areas. PMID:11932233

  12. Optogenetic control of epileptiform activity

    PubMed Central

    Tønnesen, Jan; Sørensen, Andreas T.; Deisseroth, Karl; Lundberg, Cecilia; Kokaia, Merab

    2009-01-01

    The optogenetic approach to gain control over neuronal excitability both in vitro and in vivo has emerged as a fascinating scientific tool to explore neuronal networks, but it also opens possibilities for developing novel treatment strategies for neurologic conditions. We have explored whether such an optogenetic approach using the light-driven halorhodopsin chloride pump from Natronomonas pharaonis (NpHR), modified for mammalian CNS expression to hyperpolarize central neurons, may inhibit excessive hyperexcitability and epileptiform activity. We show that a lentiviral vector containing the NpHR gene under the calcium/calmodulin-dependent protein kinase IIα promoter transduces principal cells of the hippocampus and cortex and hyperpolarizes these cells, preventing generation of action potentials and epileptiform activity during optical stimulation. This study proves a principle, that selective hyperpolarization of principal cortical neurons by NpHR is sufficient to curtail paroxysmal activity in transduced neurons and can inhibit stimulation train-induced bursting in hippocampal organotypic slice cultures, which represents a model tissue of pharmacoresistant epilepsy. This study demonstrates that the optogenetic approach may prove useful for controlling epileptiform activity and opens a future perspective to develop it into a strategy to treat epilepsy. PMID:19581573

  13. Active control of convection

    NASA Astrophysics Data System (ADS)

    Singer, Jonathan; Bau, Haim H.

    1991-12-01

    It is demonstrated theoretically that active (feedback) control can be used to alter the characteristics of thermal convection in a toroidal, vertical loop heated from below and cooled from above. As the temperature difference between the heated and cooled sections of the loop increases, the flow in the uncontrolled loop changes from no motion to steady, time-independent motion to temporally oscillatory, chaotic motion. With the use of a feedback controller effecting small perturbations in the boundary conditions, one can maintain the no-motion state at significantly higher temperature differences than the critical one corresponding to the onset of convection in the uncontrolled system. Alternatively, one can maintain steady, time-independent flow under conditions in which the flow would otherwise be chaotic. That is, the controller can be used to suppress chaos. Likewise, it is possible to stabilize periodic nonstable orbits that exist in the chaotic regime of the uncontrolled system. Finally, the controller also can be used to induce chaos in otherwise laminar (fully predictable), nonchaotic flow.

  14. Active control of combustion instabilities

    NASA Astrophysics Data System (ADS)

    Al-Masoud, Nidal A.

    A theoretical analysis of active control of combustion thermo-acoustic instabilities is developed in this dissertation. The theoretical combustion model is based on the dynamics of a two-phase flow in a liquid-fueled propulsion system. The formulation is based on a generalized wave equation with pressure as the dependent variable, and accommodates all influences of combustion, mean flow, unsteady motions and control inputs. The governing partial differential equations are converted to an equivalent set of ordinary differential equations using Galerkin's method by expressing the unsteady pressure and velocity fields as functions of normal mode shapes of the chamber. This procedure yields a representation of the unsteady flow field as a system of coupled nonlinear oscillators that is used as a basis for controllers design. Major research attention is focused on the control of longitudinal oscillations with both linear and nonlinear processes being considered. Starting with a linear model using point actuators, the optimal locations of actuators and sensors are developed. The approach relies on the quantitative measures of the degree of controllability and component cost. These criterion are arrived at by considering the energies of the system's inputs and outputs. The optimality criteria for sensor and actuator locations provide a balance between the importance of the lower order (controlled) and the higher (residual) order modes. To address the issue of uncertainties in system's parameter, the minimax principles based controller is used. The minimax corresponds to finding the best controller for the worst parameter deviation. In other words, choosing controller parameters to minimize, and parameter deviation to maximize some quadratic performance metric. Using the minimax-based controller, a remarkable improvement in the control system's ability to handle parameter uncertainties is achieved when compared to the robustness of the regular control schemes such as LQR

  15. Exercising self-control increases approach motivation.

    PubMed

    Schmeichel, Brandon J; Harmon-Jones, Cindy; Harmon-Jones, Eddie

    2010-07-01

    The present research tested the hypothesis that exercising self-control causes an increase in approach motivation. Study 1 found that exercising (vs. not exercising) self-control increases self-reported approach motivation. Study 2a identified a behavior--betting on low-stakes gambles--that is correlated with approach motivation but is relatively uncorrelated with self-control, and Study 2b observed that exercising self-control temporarily increases this behavior. Last, Study 3 found that exercising self-control facilitates the perception of a reward-relevant symbol (i.e., a dollar sign) but not a reward-irrelevant symbol (i.e., a percent sign). Altogether, these results support the hypothesis that exercising self-control temporarily increases approach motivation. Failures of self-control that follow from prior efforts at self-control (i.e., ego depletion) may be explained in part by increased approach motivation.

  16. Activity-Centric Approach to Distributed Programming

    NASA Technical Reports Server (NTRS)

    Levy, Renato; Satapathy, Goutam; Lang, Jun

    2004-01-01

    The first phase of an effort to develop a NASA version of the Cybele software system has been completed. To give meaning to even a highly abbreviated summary of the modifications to be embodied in the NASA version, it is necessary to present the following background information on Cybele: Cybele is a proprietary software infrastructure for use by programmers in developing agent-based application programs [complex application programs that contain autonomous, interacting components (agents)]. Cybele provides support for event handling from multiple sources, multithreading, concurrency control, migration, and load balancing. A Cybele agent follows a programming paradigm, called activity-centric programming, that enables an abstraction over system-level thread mechanisms. Activity centric programming relieves application programmers of the complex tasks of thread management, concurrency control, and event management. In order to provide such functionality, activity-centric programming demands support of other layers of software. This concludes the background information. In the first phase of the present development, a new architecture for Cybele was defined. In this architecture, Cybele follows a modular service-based approach to coupling of the programming and service layers of software architecture. In a service-based approach, the functionalities supported by activity-centric programming are apportioned, according to their characteristics, among several groups called services. A well-defined interface among all such services serves as a path that facilitates the maintenance and enhancement of such services without adverse effect on the whole software framework. The activity-centric application-program interface (API) is part of a kernel. The kernel API calls the services by use of their published interface. This approach makes it possible for any application code written exclusively under the API to be portable for any configuration of Cybele.

  17. Alternative approaches in schistosomiasis control.

    PubMed

    Barbosa, F S; Coimbra Júnior, C E

    1992-01-01

    Measures for the control of schistosomiasis were implemented in Egypt beginning 1922. This shows that developing endemic countries are facing this problem for near 70 years. However, results in the control of this infection have not been satisfactorily obtained in spite of the technologies and strategies recently developed. The idea that social and economic components are relevant in the control of schistosomiasis is not new although its extension and profundity have not usually been well understood. More recently, most of the workers have recognized that the focal distribution of the prevalence rates of schistosomiasis should not be neglected in the control of the infection. At present, field work projects on the control of schistosomiasis are being developed in rural areas of two Brazilian studies (Espírito Santo and Pernambuco). The adopted strategy aims to interfere in the complex relationships between man and his bio-social-cultural environment, without forgetting that the unequal distribution of the space is a consequence of the political and economic organization of the Society.

  18. 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.

  19. Computational approaches to motor control.

    PubMed

    Flash, T; Sejnowski, T J

    2001-12-01

    New concepts and computational models that integrate behavioral and neurophysiological observations have addressed several of the most fundamental long-standing problems in motor control. These problems include the selection of particular trajectories among the large number of possibilities, the solution of inverse kinematics and dynamics problems, motor adaptation and the learning of sequential behaviors.

  20. Quantifying structural controls of rockfall activity on alpine limestone cliffs: a LiDAR-based geological approach in the Wetterstein Mountains, Bavarian Alps.

    NASA Astrophysics Data System (ADS)

    Jacobs, Benjamin; Krautblatter, Michael

    2016-04-01

    In mountainous regions, rockfall represents one of the most hazardous processes potentially threatening human life and infrastructure. For risk assessment and dimensioning rockfall mitigation, a thorough understanding of rockfall processes is crucial. Here, the rate of backweathering and rockfall supply are key factors for sediment budget assessment in rock slope environments. However, recent LiDAR approaches do not cover the entire spectrum of rockfall magnitudes (e.g. small fragmental rockfall, rare large events) and many former rockfall studies do not address geological and geotechnical factors controlling rockfall. The test setup was deliberately chosen to reduce the degrees of freedom for rockfall-controlling factors. Lithology, aspect, slope gradient and porosity were kept uniform but scan sites were chosen vary bedding orientation and joint density systematically along a 600 m high limestone rock face. Terrestrial laser scanning (TLS) was used to detect and quantify rockfall activity (mm/a) at five selected rock walls of the north-facing rock slopes of the Reintal Valley over the course of one year. Additionally, structural data were obtained by traditional scanline measurements and TLS-based analysis. The compatibility of TLS methods was tested by validating the data with existing rockfall inventories obtained by direct measurements by Krautblatter et al. (2012). The results show a high discrepancy of seasonal rockfall activity between summer months (0.001 to 0.022 mm/a) and autumn to spring (0.021 to 0.364 mm/a) as well as between favorable bedding orientation (0.015 mm/a) and daylighted bedding (max. 0.264 mm/a). A significant effect of joint spacing on rockfall activity is not evident in the data or overlain by the bedding orientation effect. Nevertheless, the differences in estimated block sizes between the observed rock walls is clearly visible in the TLS derived particle size distribution. The latter was adduced to extrapolate rockfall magnitudes

  1. Immunocontraceptives: New Approaches to Fertility Control

    PubMed Central

    Kaur, Kiranjeet; Prabha, Vijay

    2014-01-01

    The rapidly increasing global population has bowed the attention of family planning and associated reproductive health programmes in the direction of providing a safe and reliable method which can be used to limit family size. The world population is estimated to exceed a phenomenal 10 billion by the year 2050 A.D., thus presenting a real jeopardy of overpopulation with severe implications for the future. Despite the availability of contraceptive methods, there are over one million elective abortions globally each year due to unintended pregnancies, having devastating impact on reproductive health of women worldwide. This highlights the need for the development of newer and improved contraceptive methods. A novel contraceptive approach that is gaining substantial attention is “immunocontraception” targeting gamete production, gamete outcome, or gamete function. Amongst these, use of sperm antigens (gamete function) seems to be an exciting and feasible approach. However, the variability of immune response and time lag to attain titer among vaccinated individuals after active immunization has highlighted the potential relevance of preformed antibodies in this league. This review is an attempt to analyze the current status and progress of immunocontraceptive approaches with respect to their establishment as a future fertility control agent. PMID:25110702

  2. Active control of convection

    SciTech Connect

    Bau, H.H.

    1995-12-31

    Using stability theory, numerical simulations, and in some instances experiments, it is demonstrated that the critical Rayleigh number for the bifurcation (1) from the no-motion (conduction) state to the motion state and (2) from time-independent convection to time-dependent, oscillatory convection in the thermal convection loop and Rayleigh-Benard problems can be significantly increased or decreased. This is accomplished through the use of a feedback controller effectuating small perturbations in the boundary data. The controller consists of sensors which detect deviations in the fluid`s temperature from the motionless, conductive values and then direct actuators to respond to these deviations in such a way as to suppress the naturally occurring flow instabilities. Actuators which modify the boundary`s temperature/heat flux are considered. The feedback controller can also be used to control flow patterns and generate complex dynamic behavior at relatively low Rayleigh numbers.

  3. Active weld control

    NASA Technical Reports Server (NTRS)

    Powell, Bradley W.; Burroughs, Ivan A.

    1994-01-01

    Through the two phases of this contract, sensors for welding applications and parameter extraction algorithms have been developed. These sensors form the foundation of a weld control system which can provide action weld control through the monitoring of the weld pool and keyhole in a VPPA welding process. Systems of this type offer the potential of quality enhancement and cost reduction (minimization of rework on faulty welds) for high-integrity welding applications. Sensors for preweld and postweld inspection, weld pool monitoring, keyhole/weld wire entry monitoring, and seam tracking were developed. Algorithms for signal extraction were also developed and analyzed to determine their application to an adaptive weld control system. The following sections discuss findings for each of the three sensors developed under this contract: (1) weld profiling sensor; (2) weld pool sensor; and (3) stereo seam tracker/keyhole imaging sensor. Hardened versions of these sensors were designed and built under this contract. A control system, described later, was developed on a multiprocessing/multitasking operating system for maximum power and flexibility. Documentation for sensor mechanical and electrical design is also included as appendices in this report.

  4. 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.

  5. A novel practical control approach for rate independent hysteretic systems.

    PubMed

    Goforth, Frank J; Zheng, Qing; Gao, Zhiqiang

    2012-05-01

    A disturbance rejection based control approach, active disturbance rejection control (ADRC), is proposed for hysteretic systems with unknown characteristics. It is an appealing alternative to hysteresis compensation because it does not require a detailed model of hysteresis, by treating the nonlinear hysteresis as a common disturbance and actively rejecting it. The stability characteristic of the ADRC is analyzed. It is shown that, in the face of the inherent dynamic uncertainties, the estimation and closed-loop tracking errors of ADRC are bounded, with their bounds monotonously decreasing with the observer and controller bandwidths, respectively. Simulation results on a typical hysteretic system further demonstrate the effectiveness of the proposed approach.

  6. Vibration control through passive constrained layer damping and active control

    NASA Astrophysics Data System (ADS)

    Lam, Margaretha J.; Inman, Daniel J.; Saunders, William R.

    1997-05-01

    To add damping to systems, viscoelastic materials (VEM) are added to structures. In order to enhance the damping effects of the VEM, a constraining layer is attached. When this constraining layer is an active element, the treatment is called active constrained layer damping (ACLD). Recently, the investigation of ACLD treatments has shown it to be an effective method of vibration suppression. In this paper, the treatment of a beam with a separate active element and passive constrained layer (PCLD) element is investigated. A Ritz- Galerkin approach is used to obtain discretized equations of motion. The damping is modeled using the GHM method and the system is analyzed in the time domain. By optimizing on the performance and control effort for both the active and passive case, it is shown that this treatment is capable of lower control effort with more inherent damping, and is therefore a better approach to damp vibration.

  7. [Approaching Physically Inactive Elderly for Physical Activity].

    PubMed

    Allmer, H; Allmer, M; Euskirchen, J; Froböse, I; Wallmann, B; Walter, T; Walschek, R

    2015-09-01

    The majority of elderly persons are still not sufficiently physically active. Therefore the aim of this study was to investigate different approaches (physical activity courses, poster, online-survey) for activating elderly to participate in physical activity. The most effective approach was target group physical activity courses with which higher course participation rates in men as well as in people with lower levels of education were achieved. Referring to the transtheoretical model (TTM) it is necessary for future analyses of target group approaches to consider more intensely the initial motivational position of physically inactive elderly.

  8. Controls Considerations for Turbine Active Clearance Control

    NASA Technical Reports Server (NTRS)

    Melcher, Kevin J.

    2004-01-01

    This presentation discusses active control of turbine tip clearance from a control systems perspective. It is a subset of charts that were presented at the 2003 meeting of the International Society of Air Breathing Engines which was held August 31 through September 5 in Cleveland, Ohio. The associated reference paper is cited at the end of the presentation. The presentation describes active tip clearance control research being conducted by NASA to improve turbine engine systems. The target application for this effort is commercial aircraft engines. However, it is believed that the technologies developed as part of this research will benefit a broad spectrum of current and future turbomachinery. The first part of the presentation discusses the concept of tip clearance, problems associated with it, and the benefits of controlling it. It lays out a framework for implementing tip clearance controls that enables the implementation to progress from purely analytical to hardware-in-the-loop to fully experimental. And it briefly discusses how the technologies developed will be married to the previously described ACC Test Rig for hardware-in-the-loop demonstrations. The final portion of the presentation, describes one of the key technologies in some detail by presenting equations and results for a functional dynamic model of the tip clearance phenomena. As shown, the model exhibits many of the clearance dynamics found in commercial gas turbine engines. However, initial attempts to validate the model identified limitations that are being addressed to make the model more realistic.

  9. Transitioning Active Flow Control to Applications

    NASA Technical Reports Server (NTRS)

    Joslin, Ronald D.; Horta, Lucas G.; Chen, Fang-Jenq

    1999-01-01

    Active Flow Control Programs at NASA, the U.S. Air Force, and DARPA have been initiated with the goals of obtaining revolutionary advances in aerodynamic performance and maneuvering compared to conventional approaches. These programs envision the use of actuators, sensors, and controllers on applications such as aircraft wings/tails, engine nacelles, internal ducts, nozzles, projectiles, weapons bays, and hydrodynamic vehicles. Anticipated benefits of flow control include reduced weight, part count, and operating cost and reduced fuel burn (and emissions), noise and enhanced safety if the sensors serve a dual role of flow control and health monitoring. To get from the bench-top or laboratory test to adaptive distributed control systems on realistic applications, reliable validated design tools are needed in addition to sub- and large-scale wind-tunnel and flight experiments. This paper will focus on the development of tools for active flow control applications.

  10. New approaches to biocide effectiveness monitoring using on-site biocide active analysis, ATP analysis, and on-line dosage/monitoring control

    SciTech Connect

    Borchardt, S.A.; Wetegrove, R.L.; Martens, J.D.

    1997-09-01

    Accurate monitoring and control of antimicrobial agents (biocides) are necessary to maintain optimum performance of industrial water systems. Evaluation of many biocides on-site is often difficult due to a lack of accurate field methods. For many non-oxidizing biocides, no field methods are available. The use of a bioluminescence bioassay allows on-site measurement of actual effective toxicant. This technology is based on a bioluminescence bioassay that measures the decrease in light output of a specific bacterium over a given time period in the presence of a toxicant. This response can be accurately correlated to the concentration of toxicant present. This system can also be used to monitor the response of microbiological populations to treatment programs by monitoring shifts in ATP levels. On-line dosage/monitoring control of a biocide product can be achieved by the addition of an inert fluorescent tracer molecule to a biocide formulation. The benefits of these traced biocides include precise documentation and on-line control of product feed and discharge, measurement of system consumption, and measurement of biocide concentration gradients throughout a system. The attributes of these new approaches to biocide effectiveness monitoring allow for more efficient and economical microbiological treatment of industrial water systems.

  11. Intelligent Control Approaches for Aircraft Applications

    NASA Technical Reports Server (NTRS)

    Gundy-Burlet, Karen; KrishnaKumar, K.; Soloway, Don; Kaneshige, John; Clancy, Daniel (Technical Monitor)

    2001-01-01

    This paper presents an overview of various intelligent control technologies currently being developed and studied under the Intelligent Flight Control (IFC) program at the NASA Ames Research Center. The main objective of the intelligent flight control program is to develop the next generation of flight controllers for the purpose of automatically compensating for a broad spectrum of damaged or malfunctioning aircraft components and to reduce control law development cost and time. The approaches being examined include: (a) direct adaptive dynamic inverse controller and (b) an adaptive critic-based dynamic inverse controller. These approaches can utilize, but do not require, fault detection and isolation information. Piloted simulation studies are performed to examine if the intelligent flight control techniques adequately: 1) Match flying qualities of modern fly-by-wire flight controllers under nominal conditions; 2) Improve performance under failure conditions when sufficient control authority is available; and 3) Achieve consistent handling qualities across the flight envelope and for different aircraft configurations. Results obtained so far demonstrate the potential for improving handling qualities and significantly increasing survivability rates under various simulated failure conditions.

  12. Motion control of 7-DOF arms: The configuration control approach

    SciTech Connect

    Homayoun Seraji; Long, M.K.; Lee, T.S. . Jet Propulsion Lab.)

    1993-04-01

    Graphics simulation and real-time implementation of configuration control schemes for a redundant 7-DOF Robotics Research arm are described. The arm kinematics and motion control schemes are described briefly. This is then followed by a description of a graphics simulation environment for 7-DOF arm control on the Silicon Graphics IRIS Workstation. Computer simulation results are presented to demonstrate elbow control, collision avoidance, and optimal joint movement as redundancy resolution goals for the 7-DOF arm. The laboratory setup for experimental validation of motion control of the 7-DOF Robotics Research arm is then described. The configuration control approach is implemented on a Motorola 68020/VME bus-based real-time controller, with elbow positioning for redundancy resolution. Experimental results demonstrate the efficacy of configuration control for real-time control of the 7-DOF arm.

  13. Motion control of 7-DOF arms - The configuration control approach

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun; Long, Mark K.; Lee, Thomas S.

    1993-01-01

    Graphics simulation and real-time implementation of configuration control schemes for a redundant 7-DOF Robotics Research arm are described. The arm kinematics and motion control schemes are described briefly. This is followed by a description of a graphics simulation environment for 7-DOF arm control on the Silicon Graphics IRIS Workstation. Computer simulation results are presented to demonstrate elbow control, collision avoidance, and optimal joint movement as redundancy resolution goals. The laboratory setup for experimental validation of motion control of the 7-DOF Robotics Research arm is then described. The configuration control approach is implemented on a Motorola-68020/VME-bus-based real-time controller, with elbow positioning for redundancy resolution. Experimental results demonstrate the efficacy of configuration control for real-time control.

  14. Systems Approach to Arms Control Verification

    SciTech Connect

    Allen, K; Neimeyer, I; Listner, C; Stein, G; Chen, C; Dreicer, M

    2015-05-15

    Using the decades of experience of developing concepts and technologies for verifying bilateral and multilateral arms control agreements, a broad conceptual systems approach is being developed that takes into account varying levels of information and risk. The IAEA has already demonstrated the applicability of a systems approach by implementing safeguards at the State level, with acquisition path analysis as the key element. In order to test whether such an approach could also be implemented for arms control verification, an exercise was conducted in November 2014 at the JRC ITU Ispra. Based on the scenario of a hypothetical treaty between two model nuclear weapons states aimed at capping their nuclear arsenals at existing levels, the goal of this exercise was to explore how to use acquisition path analysis in an arms control context. Our contribution will present the scenario, objectives and results of this exercise, and attempt to define future workshops aimed at further developing verification measures that will deter or detect treaty violations.

  15. 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.

  16. Maintenance of residual activity of Bt toxin by using natural and synthetic dyes: a novel approach for sustainable mosquito vector control.

    PubMed

    Chandrashekhar, Patil; Rahul, Suryawanshi; Hemant, Borase; Chandrakant, Narkhede; Bipinchandra, Salunke; Satish, Patil

    2015-01-01

    Mosquito control protein from Bacillus thuringiensis gets inactivated with exposure to sunlight. To address this issue, the potential of synthetic and natural dye was investigated as sunlight protectants. Bt SV2 in absence of dyes when exposed to sunlight showed reduced effectiveness against the fourth instars of mosquito larvae. Whereas acriflavin, congo red and violacein were able to maintain 86.4%, 91.6% and 82.2% mosquito larvicidal efficacy of Bt SV2 against IVth instars larvae of Anopheles stephensi Meigen after exposure to sunlight. Similarly, beetroot dye, acriflavin, congo red and violacein maintained 98.4%, 97.1%, 90.8% and 70.7% larvicidal activities against Aedes aegypti Linnaeus after sunlight exposure. Prodigiosin was found to be the best photo-protectant by simultaneously protecting and enhancing Bt activity by 6.16% and 22.16% against A. stephensi and A. aegypti, respectively. Combination of dyes with Bt formulations can be a good strategy for mosquito control programmes in tropical and sub-tropical regions.

  17. A Reinforcement Learning Approach to Control.

    DTIC Science & Technology

    1997-05-31

    acquisition is inherently a partially observable Markov decision problem. This report describes an efficient, scalable reinforcement learning approach to the...deployment of refined intelligent gaze control techniques. This report first lays a theoretical foundation for reinforcement learning . It then introduces...perform well in both high and low SNR ATR environments. Reinforcement learning coupled with history features appears to be both a sound foundation and a practical scalable base for gaze control.

  18. [The hierarchy of approaches to tobacco control

    PubMed

    Squier, Ch

    2001-01-01

    Tobacco represents the single most preventable cause of disease and death in the world today. Of 260 million male deaths in the developed world between 1950 and 2000, it is estimated that 50 million will be due to smoking. In the oral and craniofacial region tobacco use has been associated with the occurrence of cleft palate, periodontal disease and tooth loss, and a variety of soft tissue lesions including oral cancer. For example, smoking is estimated to account for 92% of cancers of the lip, oral cavity and pharynx. Few studies have examined relative efficiency of the many different approaches to tobacco control but, in general, legislative approaches such as increasing tobacco taxes and prohibiting advertising are most effective and those based on printed educational materials and cessation groups, the least effective. In all cases, advice or intervention by health care professionals ranked among the most effective non-legislative approaches to control. A very wide range of professionally-based interventions have been described, including pharmacologic interventions, behavioral approaches and group counseling. The dental profession has a unique opportunity to influence tobacco use by their patients. Its use is almost always immediately evident to the dentist or dental assistant in terms of odor, staining, poor oral hygiene or obvious oral disease. There is also a tendency for the length of personal contact with the dentist to be greater than with a physician. Guidelines are now available that provide the dental professional with advice on the best approaches to tobacco control with their patients.

  19. A Colloquial Approach: An Active Learning Technique.

    ERIC Educational Resources Information Center

    Arce, Pedro

    1994-01-01

    Addresses the problem of the effectiveness of teaching methodologies on fundamental engineering courses such as transport phenomena. Recommends the colloquial approach, an active learning strategy, to increase student involvement in the learning process. (ZWH)

  20. Demonstration of Active Combustion Control

    NASA Technical Reports Server (NTRS)

    Lovett, Jeffrey A.; Teerlinck, Karen A.; Cohen, Jeffrey M.

    2008-01-01

    The primary objective of this effort was to demonstrate active control of combustion instabilities in a direct-injection gas turbine combustor that accurately simulates engine operating conditions and reproduces an engine-type instability. This report documents the second phase of a two-phase effort. The first phase involved the analysis of an instability observed in a developmental aeroengine and the design of a single-nozzle test rig to replicate that phenomenon. This was successfully completed in 2001 and is documented in the Phase I report. This second phase was directed toward demonstration of active control strategies to mitigate this instability and thereby demonstrate the viability of active control for aircraft engine combustors. This involved development of high-speed actuator technology, testing and analysis of how the actuation system was integrated with the combustion system, control algorithm development, and demonstration testing in the single-nozzle test rig. A 30 percent reduction in the amplitude of the high-frequency (570 Hz) instability was achieved using actuation systems and control algorithms developed within this effort. Even larger reductions were shown with a low-frequency (270 Hz) instability. This represents a unique achievement in the development and practical demonstration of active combustion control systems for gas turbine applications.

  1. An Interpolation Theoretic Approach to Control

    DTIC Science & Technology

    1994-04-11

    Control 3 2.1 Causal Analytic Mappinp ....................................... 3 2.2 Causal Optimisation Problem .................................... 3...will discuss below a new approach for the approximation of Riemann mappings (conformal equivalences from simply connected sub-domains of the complex...multivariable distributed systems. (This is the most general HOO- optimisation problem.) The procedure seems to be numerically robust as evidenced by its

  2. Active Flow Control Activities at NASA Langley

    NASA Technical Reports Server (NTRS)

    Anders, Scott G.; Sellers, William L., III; Washburn, Anthony E.

    2004-01-01

    NASA Langley continues to aggressively investigate the potential advantages of active flow control over more traditional aerodynamic techniques. This paper provides an update to a previous paper and describes both the progress in the various research areas and the significant changes in the NASA research programs. The goals of the topics presented are focused on advancing the state of knowledge and understanding of controllable fundamental mechanisms in fluids as well as to address engineering challenges. An organizational view of current research activities at NASA Langley in active flow control as supported by several projects is presented. On-center research as well as NASA Langley funded contracts and grants are discussed at a relatively high level. The products of this research are to be demonstrated either in bench-top experiments, wind-tunnel investigations, or in flight as part of the fundamental NASA R&D program and then transferred to more applied research programs within NASA, DOD, and U.S. industry.

  3. A Modular Approach to Redundant Robot Control

    SciTech Connect

    Anderson, R.J.

    1997-12-01

    This paper describes a modular approach for computing redundant robot kinematics. First some conventional redundant control methods are presented and shown to be `passive control laws`, i.e. they can be represented by a network consisting of passive elements. These networks are then put into modular form by applying scattering operator techniques. Additional subnetwork modules can then be added to further shape the motion. Modules for obstacle detection, joint limit avoidance, proximity sensing, and for imposing nonlinear velocity constraints are presented. The resulting redundant robot control system is modular, flexible and robust.

  4. Fractional active disturbance rejection control.

    PubMed

    Li, Dazi; Ding, Pan; Gao, Zhiqiang

    2016-05-01

    A fractional active disturbance rejection control (FADRC) scheme is proposed to improve the performance of commensurate linear fractional order systems (FOS) and the robust analysis shows that the controller is also applicable to incommensurate linear FOS control. In FADRC, the traditional extended states observer (ESO) is generalized to a fractional order extended states observer (FESO) by using the fractional calculus, and the tracking differentiator plus nonlinear state error feedback are replaced by a fractional proportional-derivative controller. To simplify controller tuning, the linear bandwidth-parameterization method has been adopted. The impacts of the observer bandwidth ωo and controller bandwidth ωc on system performance are then analyzed. Finally, the FADRC stability and frequency-domain characteristics for linear single-input single-output FOS are analyzed. Simulation results by FADRC and ADRC on typical FOS are compared to demonstrate the superiority and effectiveness of the proposed scheme.

  5. Active Control of Stationary Vortices

    NASA Astrophysics Data System (ADS)

    Nino, Giovanni; Breidenthal, Robert; Bhide, Aditi; Sridhar, Aditya

    2016-11-01

    A system for active stationary vortex control is presented. The system uses a combination of plasma actuators, pressure sensors and electrical circuits deposited on aerodynamic surfaces using printing electronics methods. Once the pressure sensors sense a change on the intensity or on the position of the stationary vortices, its associated controller activates a set of plasma actuator to return the vortices to their original or intended positions. The forces produced by the actuators act on the secondary flow in the transverse plane, where velocities are much less than in the streamwise direction. As a demonstration case, the active vortex control system is mounted on a flat plate under low speed wind tunnel testing. Here, a set of vortex generators are used to generate the stationary vortices and the plasma actuators are used to move them. Preliminary results from the experiments are presented and compared with theoretical values. Thanks to the USAF AFOSR STTR support under contract # FA9550-15-C-0007.

  6. Extended active disturbance rejection controller

    NASA Technical Reports Server (NTRS)

    Gao, Zhiqiang (Inventor); Tian, Gang (Inventor)

    2012-01-01

    Multiple designs, systems, methods and processes for controlling a system or plant using an extended active disturbance rejection control (ADRC) based controller are presented. The extended ADRC controller accepts sensor information from the plant. The sensor information is used in conjunction with an extended state observer in combination with a predictor that estimates and predicts the current state of the plant and a co-joined estimate of the system disturbances and system dynamics. The extended state observer estimates and predictions are used in conjunction with a control law that generates an input to the system based in part on the extended state observer estimates and predictions as well as a desired trajectory for the plant to follow.

  7. Extended Active Disturbance Rejection Controller

    NASA Technical Reports Server (NTRS)

    Gao, Zhiqiang (Inventor); Tian, Gang (Inventor)

    2014-01-01

    Multiple designs, systems, methods and processes for controlling a system or plant using an extended active disturbance rejection control (ADRC) based controller are presented. The extended ADRC controller accepts sensor information from the plant. The sensor information is used in conjunction with an extended state observer in combination with a predictor that estimates and predicts the current state of the plant and a co-joined estimate of the system disturbances and system dynamics. The extended state observer estimates and predictions are used in conjunction with a control law that generates an input to the system based in part on the extended state observer estimates and predictions as well as a desired trajectory for the plant to follow.

  8. Extended Active Disturbance Rejection Controller

    NASA Technical Reports Server (NTRS)

    Gao, Zhiqiang (Inventor); Tian, Gang (Inventor)

    2016-01-01

    Multiple designs, systems, methods and processes for controlling a system or plant using an extended active disturbance rejection control (ADRC) based controller are presented. The extended ADRC controller accepts sensor information from the plant. The sensor information is used in conjunction with an extended state observer in combination with a predictor that estimates and predicts the current state of the plant and a co-joined estimate of the system disturbances and system dynamics. The extended state observer estimates and predictions are used in conjunction with a control law that generates an input to the system based in part on the extended state observer estimates and predictions as well as a desired trajectory for the plant to follow.

  9. Control approach development for variable recruitment artificial muscles

    NASA Astrophysics Data System (ADS)

    Jenkins, Tyler E.; Chapman, Edward M.; Bryant, Matthew

    2016-04-01

    This study characterizes hybrid control approaches for the variable recruitment of fluidic artificial muscles with double acting (antagonistic) actuation. Fluidic artificial muscle actuators have been explored by researchers due to their natural compliance, high force-to-weight ratio, and low cost of fabrication. Previous studies have attempted to improve system efficiency of the actuators through variable recruitment, i.e. using discrete changes in the number of active actuators. While current variable recruitment research utilizes manual valve switching, this paper details the current development of an online variable recruitment control scheme. By continuously controlling applied pressure and discretely controlling the number of active actuators, operation in the lowest possible recruitment state is ensured and working fluid consumption is minimized. Results provide insight into switching control scheme effects on working fluids, fabrication material choices, actuator modeling, and controller development decisions.

  10. How do control-based approaches enter into biology?

    PubMed

    LeDuc, Philip R; Messner, William C; Wikswo, John P

    2011-08-15

    Control is intrinsic to biological organisms, whose cells are in a constant state of sensing and response to numerous external and self-generated stimuli. Diverse means are used to study the complexity through control-based approaches in these cellular systems, including through chemical and genetic manipulations, input-output methodologies, feedback approaches, and feed-forward approaches. We first discuss what happens in control-based approaches when we are not actively examining or manipulating cells. We then present potential methods to determine what the cell is doing during these times and to reverse-engineer the cellular system. Finally, we discuss how we can control the cell's extracellular and intracellular environments, both to probe the response of the cells using defined experimental engineering-based technologies and to anticipate what might be achieved by applying control-based approaches to affect cellular processes. Much work remains to apply simplified control models and develop new technologies to aid researchers in studying and utilizing cellular and molecular processes.

  11. Dual control active superconductive devices

    DOEpatents

    Martens, Jon S.; Beyer, James B.; Nordman, James E.; Hohenwarter, Gert K. G.

    1993-07-20

    A superconducting active device has dual control inputs and is constructed such that the output of the device is effectively a linear mix of the two input signals. The device is formed of a film of superconducting material on a substrate and has two main conduction channels, each of which includes a weak link region. A first control line extends adjacent to the weak link region in the first channel and a second control line extends adjacent to the weak link region in the second channel. The current flowing from the first channel flows through an internal control line which is also adjacent to the weak link region of the second channel. The weak link regions comprise small links of superconductor, separated by voids, through which the current flows in each channel. Current passed through the control lines causes magnetic flux vortices which propagate across the weak link regions and control the resistance of these regions. The output of the device taken across the input to the main channels and the output of the second main channel and the internal control line will constitute essentially a linear mix of the two input signals imposed on the two control lines. The device is especially suited to microwave applications since it has very low input capacitance, and is well suited to being formed of high temperature superconducting materials since all of the structures may be formed coplanar with one another on a substrate.

  12. Control of tree water networks: A geometric programming approach

    NASA Astrophysics Data System (ADS)

    Sela Perelman, L.; Amin, S.

    2015-10-01

    This paper presents a modeling and operation approach for tree water supply systems. The network control problem is approximated as a geometric programming (GP) problem. The original nonlinear nonconvex network control problem is transformed into a convex optimization problem. The optimization model can be efficiently solved to optimality using state-of-the-art solvers. Two control schemes are presented: (1) operation of network actuators (pumps and valves) and (2) controlled demand shedding allocation between network consumers with limited resources. The dual of the network control problem is formulated and is used to perform sensitivity analysis with respect to hydraulic constraints. The approach is demonstrated on a small branched-topology network and later extended to a medium-size irrigation network. The results demonstrate an intrinsic trade-off between energy costs and demand shedding policy, providing an efficient decision support tool for active management of water systems.

  13. Cancer Behavior: An Optimal Control Approach

    PubMed Central

    Gutiérrez, Pedro J.; Russo, Irma H.; Russo, J.

    2009-01-01

    With special attention to cancer, this essay explains how Optimal Control Theory, mainly used in Economics, can be applied to the analysis of biological behaviors, and illustrates the ability of this mathematical branch to describe biological phenomena and biological interrelationships. Two examples are provided to show the capability and versatility of this powerful mathematical approach in the study of biological questions. The first describes a process of organogenesis, and the second the development of tumors. PMID:22247736

  14. Nonlinear systems approach to control system design

    NASA Technical Reports Server (NTRS)

    Meyer, G.

    1984-01-01

    Consider some of the control system design methods for plants with nonlinear dynamics. If the nonlinearity is weak relative to the size of the operating region, then the linear methods apply directly. Fixed-gain design may be feasible even for significant nonlinearities. It may be possible to find a single gain which provides adequate control of the linear models at several perturbation points. If the nonlinearity is restricted to a sector, that fact may be used to obtain a fixed-gain controller. Otherwise, a gain may have to be associated with each perturbation point Pi. A gain schedule K(p(v)) is obtained by connecting the perturbation points by a function, say p(v), of the scheduling parameter v (i.e., speed). When the scheduling parameter must be multidimensional, this approach is difficult; the objective is to develop an easier procedure.

  15. Active control of transmitted sound in buildings

    NASA Astrophysics Data System (ADS)

    Thompsett, Russell Harvey George

    The problem of noise from neighbours has increased dramatically over the last few years. Many of the noise complaints are due to the high level, low frequency noise from modern stereo equipment, and are often described in terms of the low frequency characteristics of the music; the repetitive, booming, bass beat. The objective of this research was to establish the feasibility of applying active noise control to alleviate this problem. The initial approach was to evaluate the possibility of exploiting the dominance of individual modes in the response of rooms at low frequency to effect global control. However, initial investigations using a modal model of the sound field revealed that this would be difficult due to the contribution of many acoustic modes excited off resonance. This conclusion was supported by measurements of acoustic room responses in typical buildings, illustrating a non-resonant characteristic. Consequently, attention was turned to the feasibility of using local active control systems to create zones of quiet by concentrating control at a specific location near the observers ears, for example in a seat headrest, or near the pillows of a bed. The lack of a reference signal in either approach requires the use of a feedback control strategy. With a typically non-resonant system, the predictability in the disturbance necessary for successful feedback control must be contained in the primary excitation, namely the music. Examples of different music styles were investigated and of those with the potential to be a nuisance surprisingly few were significantly more predictable than a random disturbance. As expected the most encouraging control performance simulations were found for modern dance music, with a strong repetitive beat. A real-time, local controller was demonstrated in the laboratory with such a disturbance signal and the properties of the quiet zone were measured. The subjective response when hearing the controller in operation was found to be

  16. Novel Active Combustion Control Valve

    NASA Technical Reports Server (NTRS)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  17. Hybrid transition control approach for plasma actuators

    NASA Astrophysics Data System (ADS)

    Kurz, A.; Goldin, N.; King, R.; Tropea, C.; Grundmann, S.

    2013-11-01

    This work reports on the development of a novel hybrid transition control method for single DBD plasma actuators. The experiments have been carried out on a natural laminar flow airfoil in a wind tunnel and combine two methods previously used for transition control purposes with DBD plasma actuators: boundary-layer stabilization by quasi-steady wall-parallel momentum addition, and active wave cancelation by linear superposition utilizing modulated momentum injection. For this purpose, the modulated body force is controlled using an improved extremum seeking controller based on an extended Kalman filter. Combining the two methods in a single actuator has advantages. Applied to 2-D Tollmien-Schlichting waves, the achievable transition delay in hybrid mode is significantly larger than the isolated effects, while the energy consumption remains almost unchanged compared to the case of continuous actuation. For a Reynolds number of , a transition delay of could be observed.

  18. Active controls for ride smoothing

    NASA Technical Reports Server (NTRS)

    Conner, D. W.; Thompson, G. O.

    1976-01-01

    Active controls technology offers great promise for significantly smoothing the ride, and thus improving public and air carrier acceptance, of certain types of transport aircraft. Recent findings which support this promise are presented in the following three pertinent areas: (1) Ride quality versus degree of traveler satisfaction; (2) significant findings from a feasibility study of a ride smoothing system; and (3) potential ride problems identified for several advanced transport concepts.

  19. Comparison of Routable Control System Security Approaches

    SciTech Connect

    Edgar, Thomas W.; Hadley, Mark D.; Carroll, Thomas E.; Manz, David O.; Winn, Jennifer D.

    2011-06-01

    This document is an supplement to the 'Secure and Efficient Routable Control Systems.' It addressed security in routable control system communication. The control system environment that monitors and manages the power grid historically has utilized serial communication mechanisms. Leased-line serial communication environments operating at 1200 to 9600 baud rates are common. However, recent trends show that communication media such as fiber, optical carrier 3 (OC-3) speeds, mesh-based high-speed wireless, and the Internet are becoming the media of choice. In addition, a dichotomy has developed between the electrical transmission and distribution environments, with more modern communication infrastructures deployed by transmission utilities. The preceding diagram represents a typical control system. The Communication Links cloud supports all of the communication mechanisms a utility might deploy between the control center and devices in the field. Current methodologies used for security implementations are primarily led by single vendors or standards bodies. However, these entities tend to focus on individual protocols. The result is an environment that contains a mixture of security solutions that may only address some communication protocols at an increasing operational burden for the utility. A single approach is needed that meets operational requirements, is simple to operate, and provides the necessary level of security for all control system communication. The solution should be application independent (e.g., Distributed Network Protocol/Internet Protocol [DNP/IP], International Electrotechnical Commission [IEC] C37.118, Object Linking and Embedding for Process Control [OPC], etc.) and focus on the transport layer. In an ideal setting, a well-designed suite of standards for control system communication will be used for vendor implementation and compliance testing. An expected outcome of this effort is an international standard.

  20. Controlling contagion processes in activity driven networks.

    PubMed

    Liu, Suyu; Perra, Nicola; Karsai, Márton; Vespignani, Alessandro

    2014-03-21

    The vast majority of strategies aimed at controlling contagion processes on networks consider the connectivity pattern of the system either quenched or annealed. However, in the real world, many networks are highly dynamical and evolve, in time, concurrently with the contagion process. Here, we derive an analytical framework for the study of control strategies specifically devised for a class of time-varying networks, namely activity-driven networks. We develop a block variable mean-field approach that allows the derivation of the equations describing the coevolution of the contagion process and the network dynamic. We derive the critical immunization threshold and assess the effectiveness of three different control strategies. Finally, we validate the theoretical picture by simulating numerically the spreading process and control strategies in both synthetic networks and a large-scale, real-world, mobile telephone call data set.

  1. A probabilistic approach to controlling crevice chemistry

    SciTech Connect

    Millett, P.J.; Brobst, G.E.; Riddle, J.

    1995-12-31

    It has been generally accepted that the corrosion of steam generator tubing could be reduced if the local pH in regions where impurities concentrate could be controlled. The practice of molar ratio control is based on this assumption. Unfortunately, due to the complexity of the crevice concentration process, efforts to model the crevice chemistry based on bulk water conditions are quite uncertain. In-situ monitoring of the crevice chemistry is desirable, but may not be achievable in the near future. The current methodology for assessing the crevice chemistry is to monitor the hideout return chemistry when the plant shuts down. This approach also has its shortcomings, but may provide sufficient data to evaluate whether the crevice pH is in a desirable range. In this paper, an approach to controlling the crevice chemistry based on a target molar ratio indicator is introduced. The molar ratio indicator is based on what is believed to be the most reliable hideout return data. Probabilistic arguments are then used to show that the crevice pH will most likely be in a desirable range when the target molar ratio is achieved.

  2. Rolling maneuver load alleviation using active controls

    NASA Technical Reports Server (NTRS)

    Woods-Vedeler, Jessica A.; Pototzky, Anthony S.

    1992-01-01

    Rolling Maneuver Load Alleviation (RMLA) was demonstrated on the Active Flexible Wing (AFW) wind tunnel model in the LaRC Transonic Dynamics Tunnel. The design objective was to develop a systematic approach for developing active control laws to alleviate wing incremental loads during roll maneuvers. Using linear load models for the AFW wind-tunnel model which were based on experimental measurements, two RMLA control laws were developed based on a single-degree-of-freedom roll model. The RMLA control laws utilized actuation of outboard control surface pairs to counteract incremental loads generated during rolling maneuvers and roll performance. To evaluate the RMLA control laws, roll maneuvers were performed in the wind tunnel at dynamic pressures of 150, 200, and 250 psf and Mach numbers of .33, .38, and .44, respectively. Loads obtained during these maneuvers were compared to baseline maneuver loads. For both RMLA controllers, the incremental torsion moments were reduced by up to 60 percent at all dynamic pressures and performance times. Results for bending moment load reductions during roll maneuvers varied. In addition, in a multiple function test, RMLA and flutter suppression system control laws were operated simultaneously during roll maneuvers at dynamic pressures 11 percent above the open-loop flutter dynamic pressure.

  3. Calculus: An Active Approach with Projects.

    ERIC Educational Resources Information Center

    Hilbert, Stephen; And Others

    1993-01-01

    Discusses a pedagogical approach to calculus based on the question: What kinds of problems should students be able to solve? Includes a discussion of types of problems and curriculum threads for such a course. Describes a projects-based calculus with examples of projects and classroom activities. (Author/MDH)

  4. A Hybrid Approach to Active Learning.

    ERIC Educational Resources Information Center

    Ramsier, R. D.

    2001-01-01

    Describes an approach to incorporate active learning strategies into the first semester of a university-level introductory physics course. Combines cooperative and peer-based methods inside the classroom with project-based learning outside the classroom in an attempt to develop students' transferable skills as well as improving their understanding…

  5. Understanding the brain by controlling neural activity

    PubMed Central

    Krug, Kristine; Salzman, C. Daniel; Waddell, Scott

    2015-01-01

    Causal methods to interrogate brain function have been employed since the advent of modern neuroscience in the nineteenth century. Initially, randomly placed electrodes and stimulation of parts of the living brain were used to localize specific functions to these areas. Recent technical developments have rejuvenated this approach by providing more precise tools to dissect the neural circuits underlying behaviour, perception and cognition. Carefully controlled behavioural experiments have been combined with electrical devices, targeted genetically encoded tools and neurochemical approaches to manipulate information processing in the brain. The ability to control brain activity in these ways not only deepens our understanding of brain function but also provides new avenues for clinical intervention, particularly in conditions where brain processing has gone awry. PMID:26240417

  6. A sequential linear optimization approach for controller design

    NASA Technical Reports Server (NTRS)

    Horta, L. G.; Juang, J.-N.; Junkins, J. L.

    1985-01-01

    A linear optimization approach with a simple real arithmetic algorithm is presented for reliable controller design and vibration suppression of flexible structures. Using first order sensitivity of the system eigenvalues with respect to the design parameters in conjunction with a continuation procedure, the method converts a nonlinear optimization problem into a maximization problem with linear inequality constraints. The method of linear programming is then applied to solve the converted linear optimization problem. The general efficiency of the linear programming approach allows the method to handle structural optimization problems with a large number of inequality constraints on the design vector. The method is demonstrated using a truss beam finite element model for the optimal sizing and placement of active/passive-structural members for damping augmentation. Results using both the sequential linear optimization approach and nonlinear optimization are presented and compared. The insensitivity to initial conditions of the linear optimization approach is also demonstrated.

  7. Optogenetic feedback control of neural activity

    PubMed Central

    Newman, Jonathan P; Fong, Ming-fai; Millard, Daniel C; Whitmire, Clarissa J; Stanley, Garrett B; Potter, Steve M

    2015-01-01

    Optogenetic techniques enable precise excitation and inhibition of firing in specified neuronal populations and artifact-free recording of firing activity. Several studies have suggested that optical stimulation provides the precision and dynamic range requisite for closed-loop neuronal control, but no approach yet permits feedback control of neuronal firing. Here we present the ‘optoclamp’, a feedback control technology that provides continuous, real-time adjustments of bidirectional optical stimulation in order to lock spiking activity at specified targets over timescales ranging from seconds to days. We demonstrate how this system can be used to decouple neuronal firing levels from ongoing changes in network excitability due to multi-hour periods of glutamatergic or GABAergic neurotransmission blockade in vitro as well as impinging vibrissal sensory drive in vivo. This technology enables continuous, precise optical control of firing in neuronal populations in order to disentangle causally related variables of circuit activation in a physiologically and ethologically relevant manner. DOI: http://dx.doi.org/10.7554/eLife.07192.001 PMID:26140329

  8. Solar and stellar activity - The theoretical approach

    NASA Astrophysics Data System (ADS)

    Belvedere, G.

    1985-10-01

    The unified approach to understanding solar and stellar activity is examined. Stellar activity observations have stimulated theoretical work, mostly within the framework of the alpha-omega dynamo theory. A number of uncertainties and intrinsic limits in dynamo theory do still exist, and these are discussed together with alternative or complementary suggestions. The relevance is stressed of nonlinear problems in dynamo theory - magnetoconvection, growth and stability of flux tubes against magnetic buoyancy, hydromagnetic global dynamos - to improve the understanding of both small and large scale interaction of rotation, turbulent convection and magnetic fields, and the transition from the linear to the nonlinear regime. Recent dynamo models of stellar activity are critically reviewed regarding the dependence of activity indexes and cycles on rotation rate and spectral type. Open problems to be solved by future work are outlined.

  9. Purposive recognition: an active and qualitative approach

    NASA Astrophysics Data System (ADS)

    Rivlin, Ehud; Aloimonos, Yiannis; Rosenfeld, Azriel

    1992-04-01

    We propose an alternative way to study the problem of visual recognition which is closer to the spirit emerging from Brooks' work on building robots than to Marr's reconstructive approach. Our theory is purposive in the sense that recognition is considered in the context of an agent performing it in an environment, along with the agent's intentions that translate into a set of behaviors; it is qualitative in the sense that only partial recovery is needed; it is active in the sense that various partial recovery tasks need for recognition are achieved through active vision; and it is opportunistic in the sense that every available cue is used.

  10. Battery charge control: Which approach is best?

    NASA Technical Reports Server (NTRS)

    Lurie, Charles

    1994-01-01

    The question of the best approach for battery charge control is addressed from two points of view: from the battery point-of-view; and from the spacecraft/mission point-of-view. In terms of performance, more aggressive charging can result in higher discharge voltage and capacity; however, aggressive charging usually implies more overcharge at higher rates and a concomitant higher end of charge temperature (higher stress, shorter life). In terms of life, benign charging can result in lower discharge voltage and capacity (poorer performance). Additionally, benign, or low stress charging, usually implies less overcharge at lower rates with lower end of charge temperature (lower stress, longer life). A discussion of these topics is presented in viewgraph form.

  11. Bladder cancer: approaches to prevention and control*

    PubMed Central

    Koroltchouk, V.; Stanley, K.; Stjernswärd, J.; Mott, K.

    1987-01-01

    Bladder cancer is the twelfth most common cancer globally, with approximately 170 000 new cases each year; a third of these cases are in the developing countries. There are two major etiological types. The first is more common in the industrialized countries and is associated with exposure to certain occupational and environmental carcinogens, but most importantly with tobacco smoking. The second type is associated with Schistosoma haematobium infection of the urinary tract and is one of the most frequent tumours in eastern Mediterranean and African countries. Both types of bladder cancer are largely preventable. Comprehensive education and legislative approaches are recommended to reduce tobacco consumption and exposure to industrial carcinogens. Safe and effective drugs are available to treat schistosomiasis within integrated control programmes in endemic areas. PMID:3121200

  12. Control-matrix approach to stellarator design and control

    SciTech Connect

    Mynick, H.E.; Pomphrey, N.

    2000-02-09

    The full space Z always equal to {l{underscore}brace}Zj=1,..Nz{r{underscore}brace} of independent variables defining a stellarator configuration is large. To find attractive design points in this space, or to understand operational flexibility about a given design point, one needs insight into the topography in Z-space of the physics figures of merit Pi which characterize the machine performance, and means of determining those directions in Z-space which give one independent control over the Pi, as well as those which affect none of them, and so are available for design flexibility. The control matrix (CM) approach described here provides a mathematical means of obtaining these. In this work, the authors describe the CM approach and use it in studying some candidate Quasi-Axisymmetric (QA) stellarator configurations the NCSX design group has been considering. In the process of the analysis, a first exploration of the topography of the configuration space in the vicinity of these candidate systems has been performed, whose character is discussed.

  13. Neutraceutical approaches to control diabetes: A natural requisite approach

    PubMed Central

    Srivastava, N.; Tiwari, G.; Tiwari, R.; Bhati, L. K.; Rai, Awani K

    2012-01-01

    Objective: The aim of this study is to screen the polyherbal preparation for antidiabetic activity in rats. Materials and Methods: The blood glucose lowering activity of the polyherbal preparation-I (1:1:1 of wheat germ oil, Coraidrum sativum, and Aloe vera) was studied in normal rats after oral administration at doses of 1.0 ml/kg and 2.0 ml/kg and polyherbal preparation-I, II (wheat germ oil, fresh juice of C. sativum, and A. vera in the ratio of 2:2:1), and III (wheat germ oil, fresh juice of C. sativum and A. vera in the ratio of 1:2:2) on alloxan-induced diabetic rats, after oral administration at doses of 1.0 ml/kg and 2.0 ml/kg. Blood samples were collected from the tail vein method at 0, 0.5, 1, 2, 4, 8, 12, and 24 h in normal rats and in diabetic rats at 0, 1, 3, 7, 15, and 30 days. Blood plasma glucose was estimated by the GOD/POD (glucose oxidase and peroxidase) method. The data were compared statistically by using the one-way ANOVA method followed by the Dunnett multiple component test. Statistical significance was set at P < 0.05. Results: The polyherbal preparation-I produced significant (P < 0.05) reduction in the blood glucose level of normal rats and polyherbal preparation-I, II, and III produced significant (P < 0.01) reduction in the blood glucose level of diabetic rats during 30-day study and compared with that of control and glibenclamide. Conclusion: The polyherbal preparation-I showed a significant glucose lowering effect in normal rats and polyherbal preparation-I, II, and III in diabetic rats. This preparation is going to be promising antidiabetic preparation for masses; however, it requires further extensive studies in human beings. PMID:23225980

  14. Distributed memory approaches for robotic neural controllers

    NASA Technical Reports Server (NTRS)

    Jorgensen, Charles C.

    1990-01-01

    The suitability is explored of two varieties of distributed memory neutral networks as trainable controllers for a simulated robotics task. The task requires that two cameras observe an arbitrary target point in space. Coordinates of the target on the camera image planes are passed to a neural controller which must learn to solve the inverse kinematics of a manipulator with one revolute and two prismatic joints. Two new network designs are evaluated. The first, radial basis sparse distributed memory (RBSDM), approximates functional mappings as sums of multivariate gaussians centered around previously learned patterns. The second network types involved variations of Adaptive Vector Quantizers or Self Organizing Maps. In these networks, random N dimensional points are given local connectivities. They are then exposed to training patterns and readjust their locations based on a nearest neighbor rule. Both approaches are tested based on their ability to interpolate manipulator joint coordinates for simulated arm movement while simultaneously performing stereo fusion of the camera data. Comparisons are made with classical k-nearest neighbor pattern recognition techniques.

  15. Shape Fixing via Salt Recrystallization: A Morphology-Controlled Approach To Convert Nanostructured Polymer to Carbon Nanomaterial as a Highly Active Catalyst for Oxygen Reduction Reaction.

    PubMed

    Ding, Wei; Li, Li; Xiong, Kun; Wang, Yao; Li, Wei; Nie, Yao; Chen, Siguo; Qi, Xueqiang; Wei, Zidong

    2015-04-29

    Herein, we report a "shape fixing via salt recrystallization" method to efficiently synthesize nitrogen-doped carbon material with a large number of active sites exposed to the three-phase zones, for use as an ORR catalyst. Self-assembled polyaniline with a 3D network structure was fixed and fully sealed inside NaCl via recrystallization of NaCl solution. During pyrolysis, the NaCl crystal functions as a fully sealed nanoreactor, which facilitates nitrogen incorporation and graphitization. The gasification in such a closed nanoreactor creates a large number of pores in the resultant samples. The 3D network structure, which is conducive to mass transport and high utilization of active sites, was found to have been accurately transferred to the final N-doped carbon materials, after dissolution of the NaCl. Use of the invented cathode catalyst in a proton exchange membrane fuel cell produces a peak power of 600 mW cm(-2), making this among the best nonprecious metal catalysts for the ORR reported so far. Furthermore, N-doped carbon materials with a nanotube or nanoshell morphology can be realized by the invented method.

  16. Distributed Energy Communications & Controls, Lab Activities - Summary

    SciTech Connect

    Rizy, D Tom

    2010-01-01

    The purpose is to develop controls for inverter-based renewable and non-renewable distributed energy systems to provide local voltage, power and power quality support for loads and the power grid. The objectives are to (1) develop adaptive controls for inverter-based distributed energy (DE) systems when there are multiple inverters on the same feeder and (2) determine the impact of high penetration high seasonal energy efficiency ratio (SEER) air conditioning (A/C) units on power systems during sub-transmission faults which can result in an A/C compressor motor stall and assess how inverter-based DE can help to mitigate the stall event. The Distributed Energy Communications & Controls Laboratory (DECC) is a unique facility for studying dynamic voltage, active power (P), non-active power (Q) and power factor control from inverter-based renewable distributed energy (DE) resources. Conventionally, inverter-based DE systems have been designed to provide constant, close to unity power factor and thus not provide any voltage support. The DECC Lab interfaces with the ORNL campus distribution system to provide actual power system testing of the controls approach. Using mathematical software tools and the DECC Lab environment, we are developing and testing local, autonomous and adaptive controls for local voltage control and P & Q control for inverter-based DE. We successfully tested our active and non-active power (P,Q) controls at the DECC laboratory along with voltage regulation controls. The new PQ control along with current limiter controls has been tested on our existing inverter test system. We have tested both non-adaptive and adaptive control modes for the PQ control. We have completed several technical papers on the approaches and results. Electric power distribution systems are experiencing outages due to a phenomenon known as fault induced delayed voltage recovery (FIDVR) due to air conditioning (A/C) compressor motor stall. Local voltage collapse from FIDVR is

  17. Active control of combustion instability

    SciTech Connect

    Lang, W.; Poinsot, T.; Candel, S.

    1987-12-01

    The principle of 'antisound' is used to construct a method for the suppression of combustion instabilities. This active instability control (AIC) method uses external acoustic excitation by a loudspeaker to suppress the oscillations of a flame. The excitation signal is provided by a microphone located upstream of the flame. This signal is filtered, processed, amplified, and sent to the loudspeaker. The AIC method is validated on a laboratory combustor. It allows the suppression of all unstable modes of the burner for any operating ratio. The influence of the microphone and loudspeaker locations on the performance of the AIC system is described. For a given configuration, domains of stability, i.e., domains where the AIC system parameters provide suppression of the oscillation, are investigated. Measurements of the electric input of the loudspeaker show that the energy consumption of the AIC system is almost negligible and suggest that this method could be used for industrial combustor stabilization. Finally, a simple model describing the effects of the AIC system is developed and its results compared to the experiment.

  18. Active thermal control system evolution

    NASA Technical Reports Server (NTRS)

    Petete, Patricia A.; Ames, Brian E.

    1991-01-01

    The 'restructured' baseline of the Space Station Freedom (SSF) has eliminated many of the growth options for the Active Thermal Control System (ATCS). Modular addition of baseline technology to increase heat rejection will be extremely difficult. The system design and the available real estate no longer accommodate this type of growth. As the station matures during its thirty years of operation, a demand of up to 165 kW of heat rejection can be expected. The baseline configuration will be able to provide 82.5 kW at Eight Manned Crew Capability (EMCC). The growth paths necessary to reach 165 kW have been identified. Doubling the heat rejection capability of SSF will require either the modification of existing radiator wings or the attachment of growth structure to the baseline truss for growth radiator wing placement. Radiator performance can be improved by enlarging the surface area or by boosting the operating temperature with a heat pump. The optimal solution will require both modifications. The addition of growth structure would permit the addition of a parallel ATCS using baseline technology. This growth system would simplify integration. The feasibility of incorporating these growth options to improve the heat rejection capacity of SSF is under evaluation.

  19. Recent advances in active control of aircraft cabin noise

    NASA Astrophysics Data System (ADS)

    Mathur, Gopal; Fuller, Christopher

    2002-11-01

    Active noise control techniques can provide significant reductions in aircraft interior noise levels without the structural modifications or weight penalties usually associated with passive techniques, particularly for low frequency noise. Our main objective in this presentation is to give a review of active control methods and their applications to aircraft cabin noise reduction with an emphasis on recent advances and challenges facing the noise control engineer in the practical application of these techniques. The active noise control method using secondary acoustic sources, e.g., loudspeakers, as control sources for tonal noise reduction is first discussed with results from an active noise control flight test demonstration. An innovative approach of applying control forces directly to the fuselage structure using piezoelectric actuators, known as active structural acoustic control (ASAC), to control cabin noise is then presented. Experimental results from laboratory ASAC tests conducted on a full-scale fuselage and from flight tests on a helicopter will be discussed. Finally, a hybrid active/passive noise control approach for achieving significant broadband noise reduction will be discussed. Experimental results of control of broadband noise transmission through an aircraft structure will be presented.

  20. Flutter suppression and gust alleviation using active controls

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1975-01-01

    Application of the aerodynamic energy approach to some problems of flutter suppression and gust alleviation were considered. A simple modification of the control-law is suggested for achieving the required pitch control in the use of a leading edge - trailing edge activated strip. The possible replacement of the leading edge - trailing edge activated strip by a trailing edge - tab strip is also considered as an alternate solution. Parameters affecting the performance of the activated leading edge - trailing edge strip were tested on the Arava STOL Transport and the Westwind Executive Jet Transport and include strip location, control-law gains and a variation in the control-law itself.

  1. Active member bridge feedback control for damping augmentation

    NASA Technical Reports Server (NTRS)

    Chen, Gun-Shing; Lurie, Boris J.

    1992-01-01

    An active damping augmentation approach using active members in a structural system is described. The problem of maximizing the vibration damping in a lightly damped structural system is considered using the analogy of impedance matching between the load and source impedances in an electrical network. The proposed active damping augmentation approach therefore consists of finding the desired active member impedances that maximize the vibration damping, and designing a feedback control in order to achieve desired active member impedances. This study uses a bridge feedback concept that feeds back a combination of signals from sensors of the axial force and relative velocity across the active member to realize the desired active member impedance. The proposed active damping augmentation approach and bridge feedback concept were demonstrated on a three-longeron softly suspended truss structure.

  2. Active Noise Control Experiments using Sound Energy Flu

    NASA Astrophysics Data System (ADS)

    Krause, Uli

    2015-03-01

    This paper reports on the latest results concerning the active noise control approach using net flow of acoustic energy. The test set-up consists of two loudspeakers simulating the engine noise and two smaller loudspeakers which belong to the active noise system. The system is completed by two acceleration sensors and one microphone per loudspeaker. The microphones are located in the near sound field of the loudspeakers. The control algorithm including the update equation of the feed-forward controller is introduced. Numerical simulations are performed with a comparison to a state of the art method minimising the radiated sound power. The proposed approach is experimentally validated.

  3. A Hybrid Nonlinear Control Scheme for Active Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Xia, F.; Albritton, N. G.; Hung, J. Y.; Nelms, R. M.

    1996-01-01

    A nonlinear control scheme for active magnetic bearings is presented in this work. Magnet winding currents are chosen as control inputs for the electromechanical dynamics, which are linearized using feedback linearization. Then, the desired magnet currents are enforced by sliding mode control design of the electromagnetic dynamics. The overall control scheme is described by a multiple loop block diagram; the approach also falls in the class of nonlinear controls that are collectively known as the 'integrator backstepping' method. Control system hardware and new switching power electronics for implementing the controller are described. Various experiments and simulation results are presented to demonstrate the concepts' potentials.

  4. Overview of Langley activities in active controls research

    NASA Technical Reports Server (NTRS)

    Abel, I.; Newsom, J. R.

    1981-01-01

    The application of active controls technology to reduce aeroelastic response of aircraft structures offers a potential for significant payoffs in terms of aerodynamic efficiency and weight savings. The activities of the Langley Research Center (laRC) in advancing active controls technology. Activities are categorized into the development of appropriate analysis tools, control law synthesis methodology, and experimental investigations aimed at verifying both analysis and synthesis methodology.

  5. Hybrid control approach for seismic coupling of two similar adjacent structures

    NASA Astrophysics Data System (ADS)

    Park, Kwan-Soon; Ok, Seung-Yong

    2015-08-01

    This study describes an optimal hybrid control approach of two similar adjacent buildings for seismic performance improvement, for which the passive dampers are used as link members between the two parallel buildings and the active control devices are installed as tendon-type devices between two successive floors in the buildings. Throughout this configuration, the passive coupling dampers modulate the relative responses between the two buildings and the active control devices modulate the inter-story responses of each building. In order to achieve global optimal control performance, genetic algorithm is employed to perform an integrated design approach for the system of buildings and hybrid control devices. Through the optimization process, the passive and active devices are optimally distributed along the floors and, simultaneously, their damping capacities and active controllers are configured in accordance with the distribution. The proposed approach is demonstrated in comparison with typical active control system which consists of two independent active systems without any connections between two buildings, each being optimal for one particular building. The numerical simulation results for a system of 20-story and 16-story buildings reveal that the proposed system can guarantee the competent control performance over the typical independent active system with less control forces and powers. As a result, it is proved that the proposed approach enables the simultaneous optimization of the control performance and the control cost.

  6. A Convex Approach to Fault Tolerant Control

    NASA Technical Reports Server (NTRS)

    Maghami, Peiman G.; Cox, David E.; Bauer, Frank (Technical Monitor)

    2002-01-01

    The design of control laws for dynamic systems with the potential for actuator failures is considered in this work. The use of Linear Matrix Inequalities allows more freedom in controller design criteria than typically available with robust control. This work proposes an extension of fault-scheduled control design techniques that can find a fixed controller with provable performance over a set of plants. Through convexity of the objective function, performance bounds on this set of plants implies performance bounds on a range of systems defined by a convex hull. This is used to incorporate performance bounds for a variety of soft and hard failures into the control design problem.

  7. Achievements and tasks for active noise control

    NASA Astrophysics Data System (ADS)

    Tichy, Jiri

    This short survey attempted to highlight some achievements of the latest active control applications. Except for the active control of a one-dimensional sound field in ducts and active headphones, the applications for active control technology are still being developed. Although the principles of active control are simple, their applications still require substantial research and modeling of the sound fields to find optimal solutions. There is no doubt that active control of sound field triggered extensive research of the fundamental properties of the sound field which goes beyond the textbook simplifications. Also, new hardware, particularly actuators, are under development. As more realism is brought into assessment of applicability of active control, we will see in the future increasing confidence of industry to adopt this new technology.

  8. Tools for active control system design

    NASA Technical Reports Server (NTRS)

    Adams, W. M., Jr.; Tiffany, S. H.; Newsom, J. R.

    1984-01-01

    Efficient control law analysis and design tools which properly account for the interaction of flexible structures, unsteady aerodynamics and active controls are developed. Development, application, validation and documentation of efficient multidisciplinary computer programs for analysis and design of active control laws are also discussed.

  9. A shooting approach to suboptimal control

    NASA Technical Reports Server (NTRS)

    Hull, David G.; Sheen, Jyh-Jong

    1991-01-01

    The shooting method is used to solve the suboptimal control problem where the control history is assumed to be piecewise linear. Suboptimal solutions can be obtained without difficulty and can lead to accurate approximate controls and good starting multipliers for the regular shooting method by increasing the number of nodes. Optimal planar launch trajectories are presented for the advanced launch system.

  10. Active control of excessive sound emission on a mobile device.

    PubMed

    Jeon, Se-Woon; Youn, Dae Hee; Park, Young-cheol; Lee, Gun-Woo

    2015-04-01

    During a phone conversation, loud vocal emission from the far-end to the near-end space can disturb nearby people. In this paper, the possibility of actively controlling such unwanted sound emission using a control source placed on the mobile device is investigated. Two different approaches are tested: Global control, minimizing the potential energy measured along a volumetric space surface, and local control, minimizing the squared sound pressure at a discrete point on the phone. From the test results, both approaches can reduce the unwanted sound emission by more than 6 dB in the frequency range up to 2 kHz.

  11. Space Station Active Thermal Control System modeling

    NASA Technical Reports Server (NTRS)

    Hye, Abdul; Lin, Chin H.

    1988-01-01

    The Space Station Active Thermal Control System (ATCS) has been modeled using modified SINDA/SINFLO programs to solve two-phase Thermo-fluid problems. The modifications include changes in several subroutines to incorporate implicit solution which allows larger time step as compared to that for explicit solutions. Larger time step saves computer time but involves larger computational error. Several runs were made using various time steps for the ATCS model. It has been found that for a reasonable approach, three times larger time step as compared to that used in explicit method is a good value which will reduce the computer time by approximately 50 percent and still maintain the accuracy of the output data to within 90 percent of the explicit values.

  12. A cascade feedback control approach for hypnosis.

    PubMed

    Puebla, Hector; Alvarez-Ramírez, José

    2005-10-01

    This article studies the problem of controlling the drug administration during an anesthesia process, where muscle relaxation, analgesia, and hypnosis are regulated by means of monitored administration of specific drugs. On the basis of a seventh-order nonlinear pharmacokinetic-pharmacodynamic representation of the hypnosis process dynamics, a cascade (master/slave) feedback control structure for controlling the bispectral index (BIS) is proposed. The master controller compares the measured BIS with its reference value to provide the expired isoflurane concentration reference to the slave controller. In turn, the slave controller manipulates the anesthetic isoflurane concentration entering the anesthetic system to achieve the reference from the master controller. The advantage of the proposed cascade control structure with respect to its noncascade counterpart is that the former provides operation protection against BIS measurement failures. In fact, under a BIS measurement fault, the master control feedback is broken and the slave controller operates under a safe reference value. Extensive numerical simulations are used to illustrate the functioning of the proposed cascade control structure.

  13. Active vibration control using mechanical and electrical analogies

    NASA Astrophysics Data System (ADS)

    Torres-Perez, A.; Hassan, A.; Kaczmarczyk, S.; Picton, P.

    2016-05-01

    Mechanical-electrical analogous circuit models are widely used in electromechanical system design as they represent the function of a coupled electrical and mechanical system using an equivalent electrical system. This research uses electrical circuits to establish a discussion of simple active vibration control principles using two scenarios: an active vibration isolation system and an active dynamic vibration absorber (DVA) using a voice coil motor (VCM) actuator. Active control laws such as gain scheduling are intuitively explained using circuit analysis techniques. Active vibration control approaches are typically constraint by electrical power requirements. The electrical analogous is a fast approach for specifying power requirements on the experimental test platform which is based on a vibration shaker that provides the based excitation required for the single Degree- of-Freedom (1DoF) vibration model under study.

  14. Developing Internal Controls through Activities

    ERIC Educational Resources Information Center

    Barnes, F. Herbert

    2009-01-01

    Life events can include the Tuesday afternoon cooking class with the group worker or the Saturday afternoon football game, but in the sense that Fritz Redl thought of them, these activities are only threads in a fabric of living that includes all the elements of daily life: playing, working, school-based learning, learning through activities,…

  15. 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.

  16. Local control approach to ultrafast electron transfer

    NASA Astrophysics Data System (ADS)

    Vindel-Zandbergen, Patricia; Meier, Christoph; Sola, Ignacio R.

    2016-10-01

    We study ultrafast electron transfer between separated nuclei using local control theory. By imposing electron ionization and electron transport through the continuum, different local control formulations are used to increase the yield of retrapping the electron at the desired nuclei. The control mechanism is based on impulsive de-excitation. Both symmetric and asymmetric nuclear arrangements are analyzed, as well as the role of the nuclear motion.

  17. Orbiter active thermal control system description

    NASA Technical Reports Server (NTRS)

    Laubach, G. E.

    1975-01-01

    A brief description of the Orbiter Active Thermal Control System (ATCS) including (1) major functional requirements of heat load, temperature control and heat sink utilization, (2) the overall system arrangement, and (3) detailed description of the elements of the ATCS.

  18. Active Control of Open Cavities

    NASA Technical Reports Server (NTRS)

    UKeiley, Lawrence

    2010-01-01

    Open loop edge blowing was demonstrated as an effective method for reducing the broad band and tonal components of the fluctuating surface pressure in open cavities. Closed loop has been successfully applied to low Mach number open cavities. Need to push actuators that are viable for closed loop control in bandwidth and output. Need a better understanding of the effects of control on the flow through detailed measurements so better actuation strategies can be developed.

  19. A hybrid approach to space power control

    NASA Technical Reports Server (NTRS)

    Gholdston, E. W.; Janik, D. F.; Newton, K. A.

    1990-01-01

    Conventional control systems have traditionally been utilized for space-based power designs. However, the use of expert systems is becoming important for NASA applications. Rocketdyne has been pursuing the development of expert systems to aid and enhance control designs of space-based power systems. The need for integrated expert systems is vital for the development of autonomous power systems.

  20. Active Flap Control of the SMART Rotor for Vibration Reduction

    NASA Technical Reports Server (NTRS)

    Hall, Steven R.; Anand, R. Vaidyanathan; Straub, Friedrich K.; Lau, Benton H.

    2009-01-01

    Active control methodologies were applied to a full-scale active flap rotor obtained during a joint Boeing/ DARPA/NASA/Army test in the Air Force National Full-Scale Aerodynamic Complex 40- by 80-foot anechoic wind tunnel. The active flap rotor is a full-scale MD 900 helicopter main rotor with each of its five blades modified to include an on-blade piezoelectric actuator-driven flap with a span of 18% of radius, 25% of chord, and located at 83% radius. Vibration control demonstrated the potential of active flaps for effective control of vibratory loads, especially normal force loads. Active control of normal force vibratory loads using active flaps and a continuous-time higher harmonic control algorithm was very effective, reducing harmonic (1-5P) normal force vibratory loads by 95% in both cruise and approach conditions. Control of vibratory roll and pitch moments was also demonstrated, although moment control was less effective than normal force control. Finally, active control was used to precisely control blade flap position for correlation with pretest predictions of rotor aeroacoustics. Flap displacements were commanded to follow specific harmonic profiles of 2 deg or more in amplitude, and the flap deflection errors obtained were less than 0.2 deg r.m.s.

  1. Conference on Geospatial Approaches to Cancer Control and Population Sciences

    Cancer.gov

    The purpose of this conference is to bring together a community of researchers across the cancer control continuum using geospatial tools, models and approaches to address cancer prevention and control.

  2. An Overview of Recent Automotive Applications of Active Vibration Control

    DTIC Science & Technology

    2004-10-01

    coordinates of the deepest point. The control signal is generated as the output of the adaptive filter. 3.2 Disturbance Observer Approach This...sign reversal, as a control signal u. To generate the estimate, a disturbance observer is used. The observer is designed off-line assuming time...2003. Disturbance - observer -based active control of engine-induced vibrations in automotive vehicles. Proceedings of the 10th Annual International

  3. Active vibration control techniques for flexible space structures

    NASA Technical Reports Server (NTRS)

    Parlos, Alexander G.; Jayasuriya, Suhada

    1990-01-01

    Two proposed control system design techniques for active vibration control in flexible space structures are detailed. Control issues relevant only to flexible-body dynamics are addressed, whereas no attempt was made to integrate the flexible and rigid-body spacecraft dynamics. Both of the proposed approaches revealed encouraging results; however, further investigation of the interaction of the flexible and rigid-body dynamics is warranted.

  4. Controller design approach based on linear programming.

    PubMed

    Tanaka, Ryo; Shibasaki, Hiroki; Ogawa, Hiromitsu; Murakami, Takahiro; Ishida, Yoshihisa

    2013-11-01

    This study explains and demonstrates the design method for a control system with a load disturbance observer. Observer gains are determined by linear programming (LP) in terms of the Routh-Hurwitz stability criterion and the final-value theorem. In addition, the control model has a feedback structure, and feedback gains are determined to be the linear quadratic regulator. The simulation results confirmed that compared with the conventional method, the output estimated by our proposed method converges to a reference input faster when a load disturbance is added to a control system. In addition, we also confirmed the effectiveness of the proposed method by performing an experiment with a DC motor.

  5. Student Activity Funds: Procedures & Controls.

    ERIC Educational Resources Information Center

    Cuzzetto, Charles E.

    Student activity funds may create educational opportunities for students, but they frequently create problems for business administrators. The first part of this work reviews the types of organizational issues and transactions an organized student group is likely to encounter, including establishing a constitution, participant roles,…

  6. Two different approaches for a control law of single gimbal control moment gyros

    NASA Technical Reports Server (NTRS)

    Schiehlen, W. O.

    1972-01-01

    In the field of momentum exchange attitude control systems, single gimbal control moment gyros (SGCMG) are of increasing interest. A gimbal angle approach and a gimbal rate approach are presented for the SGCMG control law including the singularity avoidance. Both approaches are compared and some illustrative examples are given.

  7. Control of sound radiation with active/adaptive structures

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.; Rogers, C. A.; Robertshaw, H. H.

    1992-01-01

    Recent research is discussed in the area of active structural acoustic control with active/adaptive structures. Progress in the areas of structural acoustics, actuators, sensors, and control approaches is presented. Considerable effort has been given to the interaction of these areas with each other due to the coupled nature of the problem. A discussion is presented on actuators bonded to or embedded in the structure itself. The actuators discussed are piezoceramic actuators and shape memory alloy actuators. The sensors discussed are optical fiber sensors, Nitinol fiber sensors, piezoceramics, and polyvinylidene fluoride sensors. The active control techniques considered are state feedback control techniques and least mean square adaptive algorithms. Results presented show that significant progress has been made towards controlling structurally radiated noise by active/adaptive means applied directly to the structure.

  8. A cascade control approach for a class of biomedical systems.

    PubMed

    Ortiz-Vargas, Moisés; Puebla, Hector

    2006-01-01

    An approach for the robust feedback control of a class of biomedical systems in chained form is presented. The control approach is based on modeling error compensation techniques and a recursive cascade scheme. Numerical simulations on three biomedical models of VIH-1, cancer and glucose systems are provided to illustrate our findings.

  9. A lexicographic approach to constrained MDP admission control

    NASA Astrophysics Data System (ADS)

    Panfili, Martina; Pietrabissa, Antonio; Oddi, Guido; Suraci, Vincenzo

    2016-02-01

    This paper proposes a reinforcement learning-based lexicographic approach to the call admission control problem in communication networks. The admission control problem is modelled as a multi-constrained Markov decision process. To overcome the problems of the standard approaches to the solution of constrained Markov decision processes, based on the linear programming formulation or on a Lagrangian approach, a multi-constraint lexicographic approach is defined, and an online implementation based on reinforcement learning techniques is proposed. Simulations validate the proposed approach.

  10. Actively controlled shaft seals for aerospace applications

    NASA Technical Reports Server (NTRS)

    Salant, Richard F.

    1991-01-01

    Actively controlled mechanical seals have recently been developed for industrial use. This study investigates the feasibility of using such seals for aerospace applications. In a noncontacting mechanical seal, the film thickness depends on the geometry of the seal interface. The amount of coning, which is a measure of the radial convergence or divergence of the seal interface, has a primary effect on the film thickness. Active control of the film thickness is established by controlling the coning with a piezoelectric material. A mathematical model has been formulated to predict the performance of an actively controlled mechanical seal.

  11. A sustainable approach to controlling oil spills.

    PubMed

    Al-Majed, Abdul Aziz; Adebayo, Abdulrauf Rasheed; Hossain, M Enamul

    2012-12-30

    As a result of the huge economic and environmental destruction from oil spills, studies have been directed at improving and deploying natural sorbents which are not only the least expensive but also the safest means of spill control. This research reviews the limitations and environmental impact of existing cleanup methods. It also justifies the need for concerted research effort on oil spill control using natural and sustainable technology concepts. The article proposes future guidelines for the development of a sustainable cleanup technology. Finally, guidelines for the development of a new technology for the Middle East are proposed, which is the use of an abundant resource--date palm fibers--for such techniques.

  12. Model predictive control: A new approach

    NASA Astrophysics Data System (ADS)

    Nagy, Endre

    2017-01-01

    New methods are proposed in this paper for solution of the model predictive control problem. Nonlinear state space design techniques are also treated. For nonlinear state prediction (state evolution computation) a new predictor given with an operator is introduced and tested. Settling the model predictive control problem may be obtained through application of the principle "direct stochastic optimum tracking" with a simple algorithm, which can be derived from a previously developed optimization procedure. The final result is obtained through iterations. Two examples show the applicability and advantages of the method.

  13. Stochastic Optimal Control and Linear Programming Approach

    SciTech Connect

    Buckdahn, R.; Goreac, D.; Quincampoix, M.

    2011-04-15

    We study a classical stochastic optimal control problem with constraints and discounted payoff in an infinite horizon setting. The main result of the present paper lies in the fact that this optimal control problem is shown to have the same value as a linear optimization problem stated on some appropriate space of probability measures. This enables one to derive a dual formulation that appears to be strongly connected to the notion of (viscosity sub) solution to a suitable Hamilton-Jacobi-Bellman equation. We also discuss relation with long-time average problems.

  14. Reverse Genetics Approaches to Control Arenavirus

    PubMed Central

    Martínez-Sobrido, Luis; Cheng, Benson Yee Hin; de la Torre, Juan Carlos

    2016-01-01

    Several arenavirus cause hemorrhagic fever disease in humans and pose a significant public health problem in their endemic regions. To date, no licensed vaccines are available to combat human arenavirus infections, and anti-arenaviral drug therapy is limited to an off-label use of ribavirin that is only partially effective. The development of arenavirus reverse genetics approaches provides investigators with a novel and powerful approach for the investigation of the arenavirus molecular and cell biology. The use of cell-based minigenome systems has allowed examining the cis- and trans-acting factors involved in arenavirus replication and transcription and the identification of novel anti-arenaviral drug targets without requiring the use of live forms of arenaviruses. Likewise, it is now feasible to rescue infectious arenaviruses entirely from cloned cDNAs containing predetermined mutations in their genomes to investigate virus-host interactions and mechanisms of pathogenesis, as well as to facilitate screens to identify anti-arenaviral drugs and development of novel live-attenuated arenavirus vaccines. Recently, reverse genetics have also allowed the generation of tri-segmented arenaviruses expressing foreign genes, facilitating virus detection and opening the possibility of implementing live-attenuated arenavirus-based vaccine vector approaches. Likewise, the development of single-cycle infectious, reporter-expressing, arenaviruses has provided a new experimental method to study some aspects of the biology of highly pathogenic arenaviruses without the requirement of high-security biocontainment required to study HF-causing arenaviruses. In this chapter we summarize the current knowledge on arenavirus reverse genetics and the implementation of plasmid-based reverse genetics techniques for the development of arenavirus vaccines and vaccine vectors. PMID:27076139

  15. Reverse Genetics Approaches to Control Arenavirus.

    PubMed

    Martínez-Sobrido, Luis; Cheng, Benson Yee Hin; de la Torre, Juan Carlos

    2016-01-01

    Several arenavirus cause hemorrhagic fever disease in humans and pose a significant public health problem in their endemic regions. To date, no licensed vaccines are available to combat human arenavirus infections, and anti-arenaviral drug therapy is limited to an off-label use of ribavirin that is only partially effective. The development of arenavirus reverse genetics approaches provides investigators with a novel and powerful approach for the investigation of the arenavirus molecular and cell biology. The use of cell-based minigenome systems has allowed examining the cis- and trans-acting factors involved in arenavirus replication and transcription and the identification of novel anti-arenaviral drug targets without requiring the use of live forms of arenaviruses. Likewise, it is now feasible to rescue infectious arenaviruses entirely from cloned cDNAs containing predetermined mutations in their genomes to investigate virus-host interactions and mechanisms of pathogenesis, as well as to facilitate screens to identify anti-arenaviral drugs and development of novel live-attenuated arenavirus vaccines. Recently, reverse genetics have also allowed the generation of tri-segmented arenaviruses expressing foreign genes, facilitating virus detection and opening the possibility of implementing live-attenuated arenavirus-based vaccine vector approaches. Likewise, the development of single-cycle infectious, reporter-expressing, arenaviruses has provided a new experimental method to study some aspects of the biology of highly pathogenic arenaviruses without the requirement of high-security biocontainment required to study HF-causing arenaviruses. In this chapter we summarize the current knowledge on arenavirus reverse genetics and the implementation of plasmid-based reverse genetics techniques for the development of arenavirus vaccines and vaccine vectors.

  16. Active noise control using a distributed mode flat panel loudspeaker.

    PubMed

    Zhu, H; Rajamani, R; Dudney, J; Stelson, K A

    2003-07-01

    A flat panel distributed mode loudspeaker (DML) has many advantages over traditional cone speakers in terms of its weight, size, and durability. However, its frequency response is uneven and complex, thus bringing its suitability for active noise control (ANC) under question. This paper presents experimental results demonstrating the effective use of panel DML speakers in an ANC application. Both feedback and feedforward control techniques are considered. Effective feedback control with a flat panel speaker could open up a whole range of new noise control applications and has many advantages over feedforward control. The paper develops a new control algorithm to attenuate tonal noise of a known frequency by feedback control. However, due to the uneven response of the speakers, feedback control is found to be only moderately effective even for this narrow-band application. Feedforward control proves to be most capable for the flat panel speaker. Using feedforward control, the sound pressure level can be significantly reduced in close proximity to an error microphone. The paper demonstrates an interesting application of the flat panel in which the panel is placed in the path of sound and effectively used to block sound transmission using feedforward control. This is a new approach to active noise control enabled by the use of flat panels and can be used to prevent sound from entering into an enclosure in the first place rather than the traditional approach of attempting to cancel sound after it enters the enclosure.

  17. Novel approach to visual robot control

    NASA Astrophysics Data System (ADS)

    Prljaca, Naser; McCabe, Hugh

    1995-10-01

    In this paper a new control scheme for a robot manipulator based on visual information is proposed. The control system determines the position and orientation of the robot gripper in order to achieve desired grasping relation between the gripper and a 3D object. The proposed control scheme consists of two distinct stages: (1) Learning stage, in this stage the robot system reconstructs a 3D geometrical model of a presented unknown object within a class of objects (polyhedra), by integrating information from an image sequence obtained from a camera mounted on the robot manipulator (eye-in-hand). This model is represented by a set of 3D line segments and denoted as a reference model. The robot is also taught desired grasping relation by manual guidance. (2) Execution stage, in this stage the robot system reconstructs a 3D model of the arbitrarily placed 3D object. This model is denoted as an observed model. Then, the necessary position and orientation of its gripper is determined based on estimated 3D displacement between the reference and observed models. Further, the basic algorithm is extended to handle multiple objects manipulation and recognition. The performance of the proposed algorithms has been tested on the real robot system and the experimental results are presented.

  18. Fuel conservation through active control of rotor clearances

    NASA Technical Reports Server (NTRS)

    Beitler, R. S.; Saunders, A. A.; Wanger, R. P.

    1980-01-01

    Under the NASA-sponsored Energy Efficient Engine (EEE) Project, technology is being developed which will significantly reduce the fuel consumption of turbofan engines for subsonic transport aircraft. One technology concept being pursued is active control of rotor tip clearances. Attention is given to rotor tip clearance considerations and an overview of preliminary study results as well as the General Electric EEE clearance control approach is presented. Finally, potential fuel savings with active control of rotor clearances for a typical EEE mission are predicted.

  19. Active Control of Transition and Turbulence

    NASA Technical Reports Server (NTRS)

    Maestrello, Lucio

    1987-01-01

    Two active means of manipulating boundary-layer flow developed, one controlling laminar-to-turbulent transition, other controlling amplitude of turbulent fluctuation. Purpose to control skin-friction drag over surfaces inside inlets and ducts. Resulting turbulence downstream has lower skin-friction drag than equivalent flow developing over same surfaces in absence of intervention. Heating strips trigger turbulence while transition amplitude and bandwidth controlled by acoustic signal.

  20. A Numerical Optimization Approach for Tuning Fuzzy Logic Controllers

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Garg, Devendra P.

    1998-01-01

    This paper develops a method to tune fuzzy controllers using numerical optimization. The main attribute of this approach is that it allows fuzzy logic controllers to be tuned to achieve global performance requirements. Furthermore, this approach allows design constraints to be implemented during the tuning process. The method tunes the controller by parameterizing the membership functions for error, change-in-error and control output. The resulting parameters form a design vector which is iteratively changed to minimize an objective function. The minimal objective function results in an optimal performance of the system. A spacecraft mounted science instrument line-of-sight pointing control is used to demonstrate results.

  1. Experimental demonstration of a classical approach for flexible space structure control: NASA CSI testbeds

    NASA Technical Reports Server (NTRS)

    Bond, Wie

    1991-01-01

    The results of active control experiments performed for the Mini-Mast truss structure are presented. The primary research objectives were: (1) to develop active structural control concepts and/or techniques; (2) to verify the concept of robust non-minimum-phase compensation for a certain class of non-colocated structural control problems through ground experiments; (3) to verify a 'dipole' concept for persistent disturbance rejection control of flexible structures; and (4) to identify CSI (Control Structure Interaction) issues and areas of emphasis for the next generation of large flexible spacecraft. The classical SISO (Single Input and Single Output) control design approach was employed.

  2. Reliable and Affordable Control Systems Active Combustor Pattern Factor Control

    NASA Technical Reports Server (NTRS)

    McCarty, Bob; Tomondi, Chris; McGinley, Ray

    2004-01-01

    Active, closed-loop control of combustor pattern factor is a cooperative effort between Honeywell (formerly AlliedSignal) Engines and Systems and the NASA Glenn Research Center to reduce emissions and turbine-stator vane temperature variations, thereby enhancing engine performance and life, and reducing direct operating costs. Total fuel flow supplied to the engine is established by the speed/power control, but the distribution to individual atomizers will be controlled by the Active Combustor Pattern Factor Control (ACPFC). This system consist of three major components: multiple, thin-film sensors located on the turbine-stator vanes; fuel-flow modulators for individual atomizers; and control logic and algorithms within the electronic control.

  3. Active Shielding and Control of Environmental Noise

    NASA Technical Reports Server (NTRS)

    Tsynkov, S. V.

    2001-01-01

    In the framework of the research project supported by NASA under grant # NAG-1-01064, we have studied the mathematical aspects of the problem of active control of sound, i.e., time-harmonic acoustic disturbances. The foundations of the methodology are described in our paper [1]. Unlike. many other existing techniques, the approach of [1] provides for the exact volumetric cancellation of the unwanted noise on a given predetermined region airspace, while leaving unaltered those components of the total acoustic field that are deemed as friendly. The key finding of the work is that for eliminating the unwanted component of the acoustic field in a given area, one needs to know relatively little; in particular, neither the locations nor structure nor strength of the exterior noise sources need to be known. Likewise, there is no need to know the volumetric properties of the supporting medium across which the acoustic signals propagate, except, maybe, in a narrow area of space near the perimeter of the protected region. The controls are built based solely on the measurements performed on the perimeter of the domain to be shielded; moreover, the controls themselves (i.e., additional sources) are concentrated also only on or near this perimeter. Perhaps as important, the measured quantities can refer to the total acoustic field rather than to its unwanted component only, and the methodology can automatically distinguish between the two. In [1], we have constructed the general solution for controls. The apparatus used for deriving this general solution is closely connected to the concepts of generalized potentials and boundary projections of Calderon's type. For a given total wave field, the application of a Calderon's projection allows one to definitively tell between its incoming and outgoing components with respect to a particular domain of interest, which may have arbitrary shape. Then, the controls are designed so that they suppress the incoming component for the domain

  4. Analysis and control of unified active power filter

    NASA Astrophysics Data System (ADS)

    Muthu, Subramanian

    1999-11-01

    The combined series and shunt active filters have been proposed to alleviate the power quality problems at the demand-side power systems. However, the conventional approach for the control of the combined active filter systems have resulted in large operating capacity of the shunt active filter because reactive power compensation involves only the shunt active filter. Furthermore, the harmonic mitigation problems are handled mainly by indirect harmonic compensation schemes rather than direct harmonic isolation schemes. This thesis presents the analysis and control of Unified Active Power Filter (UAPF) and proposes a novel concept of load reactive power compensation involving both the series active filter and the shunt active filter. The thesis also applies discrete-time sliding-mode control technique to enhance the performance of the combined active filter system in terms of fast dynamic response and effective solution to harmonic mitigation problems. The thesis also presents simulation and experimental results to provide verification of the proposed UAPF concept. The involvement of series active filter for reactive power compensation is achieved by controlling the phase difference between the load voltage and the utility voltage. The complete steady-state operating characteristics of UAPF are analyzed with the identification of the different operating modes of UAPF and the analysis of active and reactive power handled by the active filter components. The performance of UAPF to meet the stringent power quality standards are realized by applying discrete-time sliding-mode control schemes for the load voltage regulation and the active power factor correction. The control algorithms are developed to track a given load voltage and line current reference signals respectively. The effect of computational delay in DSP implementation is studied extensively and the control law is designed with the consideration for the computational delay. The systematic approach for the

  5. Active Control by Conservation of Energy Concept

    NASA Technical Reports Server (NTRS)

    Maestrello, Lucio

    2000-01-01

    Three unrelated experiments are discussed; each was extremely sensitive to initial conditions. The initial conditions are the beginnings of the origins of the information that nonlinearity displays. Initial conditions make the phenomenon unstable and unpredictable. With the knowledge of the initial conditions, active control requires far less power than that present in the system response. The first experiment is on the control of shocks from an axisymmetric supersonic jet; the second, control of a nonlinear panel response forced by turbulent boundary layer and sound; the third, control of subharmonic and harmonics of a panel forced by sound. In all three experiments, control is achieved by redistribution of periodic energy response such that the energy is nearly preserved from a previous uncontrolled state. This type of active control improves the performance of the system being controlled.

  6. Follow-up of nosocomial infections on nursing units: an approach to infection control.

    PubMed

    Loss, S L; Goodloe, S

    1986-07-01

    The infection control department at Niagara Falls Memorial Medical Center in Niagara Falls, New York, has developed an innovative approach to decreasing nosocomial infections. By following up on the infections that occur on nursing units, nurses actively work to prevent their occurrence. The approach utilizes nursing accountability, continuing staff education, and documentation, with positive results.

  7. Active control of buildings during earthquakes

    NASA Technical Reports Server (NTRS)

    Vance, Vicki L.

    1993-01-01

    The objective of this report is to provide an overview of the different types of control systems used in buildings, to discuss the problems associated with current active control mechanisms, and to show the cost-effectiveness of applying active control to buildings. In addition, a small case study investigates the feasibility and benefits of using embedded actuators in buildings. Use of embedded actuators could solve many of the current problems associated with active control by providing a wider bandwidth of control, quicker speed of response, increased reliability and reduced power requirement. Though embedded actuators have not been developed for buildings, they have previously been used in space structures. Many similarities exist between large civil and aerospace structures indicating that direct transfer of concepts between the two disciplines may be possible. In particular, much of the Controls-Structures Interaction (CSI) technology currently being developed could be beneficially applied to civil structures. While several buildings with active control systems have been constructed in Japan, additional research and experimental verification are necessary before active control systems become widely accepted and implemented.

  8. Controls on fire activity over the Holocene

    NASA Astrophysics Data System (ADS)

    Kloster, S.; Brücher, T.; Brovkin, V.; Wilkenskjeld, S.

    2014-11-01

    Changes in fire activity over the last 8000 years are simulated with a global fire model driven by changes in climate and vegetation cover. The changes were separated into those caused through variations in fuel availability, fuel moisture or wind speed which react differently to changes in climate. Disentangling these controlling factors helps to understand the overall climate control on fire activity over the Holocene. Globally the burned area is simulated to increase by 2.5% between 8000 and 200 cal yr BP with larger regional changes compensating on a global scale. Despite the absence of anthropogenic fire ignitions, the simulated trends in fire activity agree reasonably well with continental scale reconstructions from charcoal records, with the exception of Europe. For some regions the change in fire activity is predominantly controlled through changes in fuel availability (Australia-Monsoon, American Tropics/Subtropics). For other regions changes in fuel moisture are more important for the overall trend in fire activity (North America, Sub-Saharan Africa, Europe, Asia-Monsoon). In Sub-Saharan Africa, for example, changes in fuel moisture alone lead to an increase in fire activity between 8000 and 200 cal yr BP, while changes in fuel availability lead to a decrease. Overall, the fuel moisture control is dominating the simulated fire activity for Sub-Saharan Africa. The simulations clearly demonstrate that both changes in fuel availability and changes in fuel moisture are important drivers for the fire activity over the Holocene. Fuel availability and fuel moisture do, however, have different climate controls. As such observed changes in fire activity can not be related to single climate parameters such as precipitation or temperature alone. Fire models, as applied in this study, in combination with observational records can help to understand the climate control on fire activity, which is essential to project future fire activity.

  9. Controls on fire activity over the Holocene

    NASA Astrophysics Data System (ADS)

    Kloster, S.; Brucher, T.; Brovkin, V.; Wilkenskjeld, S.

    2015-05-01

    Changes in fire activity over the last 8000 years are simulated with a global fire model driven by changes in climate and vegetation cover. The changes were separated into those caused through variations in fuel availability, fuel moisture or wind speed, which react differently to changes in climate. Disentangling these controlling factors helps in understanding the overall climate control on fire activity over the Holocene. Globally the burned area is simulated to increase by 2.5% between 8000 and 200 cal yr BP, with larger regional changes compensating nearly evening out on a global scale. Despite the absence of anthropogenic fire ignitions, the simulated trends in fire activity agree reasonably well with continental-scale reconstructions from charcoal records, with the exception of Europe. For some regions the change in fire activity is predominantly controlled through changes in fuel availability (Australia monsoon, Central America tropics/subtropics). For other regions changes in fuel moisture are more important for the overall trend in fire activity (North America, Sub-Saharan Africa, Europe, Asia monsoon). In Sub-Saharan Africa, for example, changes in fuel moisture alone lead to an increase in fire activity between 8000 and 200 cal yr BP, while changes in fuel availability lead to a decrease. Overall, the fuel moisture control is dominating the simulated fire activity for Sub-Saharan Africa. The simulations clearly demonstrate that both changes in fuel availability and changes in fuel moisture are important drivers for the fire activity over the Holocene. Fuel availability and fuel moisture do, however, have different climate controls. As such, observed changes in fire activity cannot be related to single climate parameters such as precipitation or temperature alone. Fire models, as applied in this study, in combination with observational records can help in understanding the climate control on fire activity, which is essential to project future fire

  10. [Pharmacological approaches to control of body temperature].

    PubMed

    Soto Ruiz, M Nelia; Ezquerro Rodríguez, Esther; Marín Fernández, Blanca

    2012-05-01

    The main antipyretic drugs belong to two different therapeutic groups: non-steroidal anti-inflammatory and antirheumatic; and analgesic and antipyretic. In some cases, both groups are included in the NSAID group (analgesics antipyretics and NSAID). Most of the chemical compounds included in this group have three actions, but the relative performance of each of them can be different, as well as the incidence of adverse effects. For this reason its clinical use will depend on effectiveness and relative toxicity. When there is fever, NSAID normalizes the action of the thermoregulatory center in the hypothalamus, decreasing production of prostaglandins by inhibiting enzymes cyclooxygenase. But not all are capable of controlling the temperature which increases in adaptative physiological situations, as in heat stroke, intense exercise or by increasing the temperature. The classification is based on chemical characteristics and can be grouped into nine classes: 1) Salicylates, 2) Para-aminophenol derivatives, 3) Derivatives of pyrazolone, 4) Acetic acid derivatives, 5) Derivatives propionic acid, 6) Anthranilic derivatives, 7) Oxicam derivatives, 8) COX-2 inhibitors, 9) Other NSAID. This article describes the indications, mechanism of action, clinical presentation, routes of administration, adverse reactions, contraindications, precautions and drug interactions of the most commonly used (Derivatives of Salicylic Acid, Paracetamol, Metamizole, Ibuprofen, Drantoleno).

  11. More choices of birth control approaches.

    PubMed

    Ni, Y

    1985-03-01

    In rural Zhejiang Province, China, family planning intermediaries are appointed for each village to introduce comprehensive measures of birth control to the people. With an education level of junior middle school at least, they are mostly working women of high prestige in their villages. After appointment as intermediaries, these women are trained for 1-2 weeks in health stations or maternal and child health care stations in towns. Back in the villages, they take over responsibility for distributing monthly contraceptives as needed by women of childbearing age. The intermediaries also explain the advantages and disadvantages of different kinds of contraceptives to newly wedded women and give them guidance and recommendations. Intermediaries also can provide simple treatment for complaints caused by contraceptive use. For example, if women complain of nausea while 1st taking oral contraceptives (OCs), the intermediaries will give them vitamin B6. When intermediairies encounter difficulties, such as women who cannot use OCs for a long time because of a liver ailment, they refer the people to health stations or send for a doctor. The number of induced abortions has declined because of the fact that a vast number of women of childbearing age in rural areas now obtain appropriate contraceptives in time. Generally, each intermediary is assigned to be in charge of 15-20 households, making a regular monthly visit to each of these families. The contraceptives they distribute are from town governments, which give them a certain amount of annual subsidies.

  12. Monitoring by Control Technique - Activated Carbon Adsorber

    EPA Pesticide Factsheets

    Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about Activated Carbon Adsorber control techniques used to reduce pollutant emissions.

  13. Active control of turbomachine discrete tones

    NASA Astrophysics Data System (ADS)

    Fleeter, Sanford

    This paper was directed at active control of discrete frequency noise generated by subsonic blade rows through cancellation of the blade row interaction generated propagating acoustic waves. First discrete frequency noise generated by a rotor and stator in a duct was analyzed to determine the propagating acoustic pressure waves. Then a mathematical model was developed to analyze and predict the active control of discrete frequency noise generated by subsonic blade rows through cancellation of the propagating acoustic waves, accomplished by utilizing oscillating airfoil surfaces to generate additional control propagating pressure waves. These control waves interact with the propagating acoustic waves, thereby, in principle, canceling the acoustic waves and thus, the far field discrete frequency tones. This model was then applied to a fan exit guide vane to investigate active airfoil surface techniques for control of the propagating acoustic waves, and thus the far field discrete frequency tones, generated by blade row interactions.

  14. Approximate active fault detection and control

    NASA Astrophysics Data System (ADS)

    Škach, Jan; Punčochář, Ivo; Šimandl, Miroslav

    2014-12-01

    This paper deals with approximate active fault detection and control for nonlinear discrete-time stochastic systems over an infinite time horizon. Multiple model framework is used to represent fault-free and finitely many faulty models. An imperfect state information problem is reformulated using a hyper-state and dynamic programming is applied to solve the problem numerically. The proposed active fault detector and controller is illustrated in a numerical example of an air handling unit.

  15. Active Polymer Microfiber with Controlled Polarization Sensitivity

    PubMed Central

    Xia, Hongyan; Wang, Ruxue; Liu, Yingying; Cheng, Junjie; Zou, Gang; Zhang, Qijin; Zhang, Douguo; Wang, Pei; Ming, Hai; Badugu, Ramachandram; Lakowicz, Joseph R.

    2016-01-01

    Controlled Polarization Sensitivity of an active polymer microfiber has been proposed and realized with the electrospun method. The fluorescence intensity guiding through this active polymer microfiber shows high sensitivity to the polarization state of the excitation light. What is more, the fluorescence out-coupled from tip of the microfiber can be of designed polarization state. Principle of these phenomena lies on the ordered and controlled orientation of the polydiacetylene (PDA) main chains inside polymer microfiber. PMID:27099828

  16. An extended active control for chaos synchronization

    NASA Astrophysics Data System (ADS)

    Tang, Rong-An; Liu, Ya-Li; Xue, Ju-Kui

    2009-04-01

    By introducing a control strength matrix, the active control theory in chaotic synchronization is developed. With this extended method, chaos complete synchronization can be achieved more easily, i.e., a much smaller control signal is enough to reach synchronization in most cases. Numerical simulations on Rossler, Liu's four-scroll, and Chen system confirmed this and show that the synchronization result depends on the control strength significantly. Especially, in the case of Liu and Chen systems, the response systems' largest Lyapunov exponents' variation with the control strength is not monotone and there exist minima. It is novel for Chen system that the synchronization speed with a special small strength is higher than that of the usual active control which, as a special case of the extended method, has a much larger control strength. All these results indicate that the control strength is an important factor in the actual synchronization. So, with this extended active control, one can make a better and more practical synchronization scheme by adjusting the control strength matrix.

  17. Communication and remote control approaches to road surface carrying system

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Wang, Jin

    2013-07-01

    In this paper, we present a novel control approach which is fusion techniques of factory automation/management and functions of hardware for computer communication. We describe the communication techniques between computer and programmable logic controller based on special system protocols. The developed controller innovated prior knowledge from some files, is considered as guides for the relevant controller designers and programmers, and a reference on establishing practical database for intelligent agents and on communication tasks.

  18. A computer-aided approach to nonlinear control systhesis

    NASA Technical Reports Server (NTRS)

    Wie, Bong; Anthony, Tobin

    1988-01-01

    The major objective of this project is to develop a computer-aided approach to nonlinear stability analysis and nonlinear control system design. This goal is to be obtained by refining the describing function method as a synthesis tool for nonlinear control design. The interim report outlines the approach by this study to meet these goals including an introduction to the INteractive Controls Analysis (INCA) program which was instrumental in meeting these study objectives. A single-input describing function (SIDF) design methodology was developed in this study; coupled with the software constructed in this study, the results of this project provide a comprehensive tool for design and integration of nonlinear control systems.

  19. Aircraft Control Strategies by Game Theoretic Approach against Wind Shear

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Masahiro; Umemura, Akira

    The safety problem of aircraft that encounters wind shear during the final approach flight phase is addressed using a game theoretic approach. The game consists of two players, an aircraft and wind shear. The control scheme is composed of non-cooperative game between players. In the game, aircraft tries to fly to avoid crashing to ground and down burst attempts to force the aircraft to crash. A new control strategy based on nonlinear receding horizon control is applied to the game. It is shown by simulation that this control strategy is effective against wind shear.

  20. Active load control techniques for wind turbines.

    SciTech Connect

    van Dam, C.P.; Berg, Dale E.; Johnson, Scott J.

    2008-07-01

    This report provides an overview on the current state of wind turbine control and introduces a number of active techniques that could be potentially used for control of wind turbine blades. The focus is on research regarding active flow control (AFC) as it applies to wind turbine performance and loads. The techniques and concepts described here are often described as 'smart structures' or 'smart rotor control'. This field is rapidly growing and there are numerous concepts currently being investigated around the world; some concepts already are focused on the wind energy industry and others are intended for use in other fields, but have the potential for wind turbine control. An AFC system can be broken into three categories: controls and sensors, actuators and devices, and the flow phenomena. This report focuses on the research involved with the actuators and devices and the generated flow phenomena caused by each device.

  1. Student Activity Funds: Procedures and Controls.

    ERIC Educational Resources Information Center

    Cuzzetto, Charles E.

    2000-01-01

    An effective internal-control system can help school business administrators meet the challenges of accounting for student activity funds. Such a system should include appropriate policies and procedures, identification of key control points, self-assessments, audit trails, and internal and external audits. (MLH)

  2. The development of the Final Approach Spacing Tool (FAST): A cooperative controller-engineer design approach

    NASA Technical Reports Server (NTRS)

    Lee, Katharine K.; Davis, Thomas J.

    1995-01-01

    Historically, the development of advanced automation for air traffic control in the United States has excluded the input of the air traffic controller until the need of the development process. In contrast, the development of the Final Approach Spacing Tool (FAST), for the terminal area controller, has incorporated the end-user in early, iterative testing. This paper describes a cooperative between the controller and the developer to create a tool which incorporates the complexity of the air traffic controller's job. This approach to software development has enhanced the usability of FAST and has helped smooth the introduction of FAST into the operational environment.

  3. Exercising self-control increases relative left frontal cortical activation.

    PubMed

    Schmeichel, Brandon J; Crowell, Adrienne; Harmon-Jones, Eddie

    2016-02-01

    Self-control refers to the capacity to override or alter a predominant response tendency. The current experiment tested the hypothesis that exercising self-control temporarily increases approach motivation, as revealed by patterns of electrical activity in the prefrontal cortex. Participants completed a writing task that did vs did not require them to exercise self-control. Then they viewed pictures known to evoke positive, negative or neutral affect. We assessed electroencephalographic (EEG) activity while participants viewed the pictures, and participants reported their trait levels of behavioral inhibition system (BIS) and behavioral activation system (BAS) sensitivity at the end of the study. We found that exercising (vs not exercising) self-control increased relative left frontal cortical activity during picture viewing, particularly among individuals with relatively higher BAS than BIS, and particularly during positive picture viewing. A similar but weaker pattern emerged during negative picture viewing. The results suggest that exercising self-control temporarily increases approach motivation, which may help to explain the aftereffects of self-control (i.e. ego depletion).

  4. A multidisciplinary approach to optimization of controlled space structures

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Padula, Sharon L.; Graves, Philip C.; James, Benjamin B.

    1990-01-01

    A fundamental problem facing controls-structures analysts is a means of determining the trade-offs between structural design parameters and control design parameters in meeting some particular performance criteria. Developing a general optimization-based design methodology integrating the disciplines of structural dynamics and controls is a logical approach. The objective of this study is to develop such a method. Classical design methodology involves three phases. The first is structural optimization, wherein structural member sizes are varied to minimize structural mass, subject to open-loop frequency constraints. The next phase integrates control and structure design with control gains as additional design variables. The final phase is analysis of the 'optimal' integrated design phase considering 'real' actuators and 'standard' member sizes. The control gains could be further optimized for fixed structure, and actuator saturation constraints could be imposed. However, such an approach does not take full advantage of opportunities to tailor the structure and control system design as one system.

  5. A theoretical approach on controlling agricultural pest by biological controls.

    PubMed

    Mondal, Prasanta Kumar; Jana, Soovoojeet; Kar, T K

    2014-03-01

    In this paper we propose and analyze a prey-predator type dynamical system for pest control where prey population is treated as the pest. We consider two classes for the pest namely susceptible pest and infected pest and the predator population is the natural enemy of the pest. We also consider average delay for both the predation rate i.e. predation to the susceptible pest and infected pest. Considering a subsystem of original system in the absence of infection, we analyze the existence of all possible non-negative equilibria and their stability criteria for both the subsystem as well as the original system. We present the conditions for transcritical bifurcation and Hopf bifurcation in the disease free system. The theoretical evaluations are demonstrated through numerical simulations.

  6. An Analytical Dynamics Approach to the Control of Mechanical Systems

    NASA Astrophysics Data System (ADS)

    Mylapilli, Harshavardhan

    A new and novel approach to the control of nonlinear mechanical systems is presented in this study. The approach is inspired by recent results in analytical dynamics that deal with the theory of constrained motion. The control requirements on the dynamical system are viewed from an analytical dynamics perspective and the theory of constrained motion is used to recast these control requirements as constraints on the dynamical system. Explicit closed form expressions for the generalized nonlinear control forces are obtained by using the fundamental equation of mechanics. The control so obtained is optimal at each instant of time and causes the constraints to be exactly satisfied. No linearizations and/or approximations of the nonlinear dynamical system are made, and no a priori structure is imposed on the nature of nonlinear controller. Three examples dealing with highly nonlinear complex dynamical systems that are chosen from diverse areas of discrete and continuum mechanics are presented to demonstrate the control approach. The first example deals with the energy control of underactuated inhomogeneous nonlinear lattices (or chains), the second example deals with the synchronization of the motion of multiple coupled slave gyros with that of a master gyro, and the final example deals with the control of incompressible hyperelastic rubber-like thin cantilever beams. Numerical simulations accompanying these examples show the ease, simplicity and the efficacy with which the control methodology can be applied and the accuracy with which the desired control objectives can be met.

  7. Control of nucleus accumbens activity with neurofeedback.

    PubMed

    Greer, Stephanie M; Trujillo, Andrew J; Glover, Gary H; Knutson, Brian

    2014-08-01

    The nucleus accumbens (NAcc) plays critical roles in healthy motivation and learning, as well as in psychiatric disorders (including schizophrenia and attention deficit hyperactivity disorder). Thus, techniques that confer control of NAcc activity might inspire new therapeutic interventions. By providing second-to-second temporal resolution of activity in small subcortical regions, functional magnetic resonance imaging (fMRI) can resolve online changes in NAcc activity, which can then be presented as "neurofeedback." In an fMRI-based neurofeedback experiment designed to elicit NAcc activity, we found that subjects could increase their own NAcc activity, and that display of neurofeedback significantly enhanced their ability to do so. Subjects were not as capable of decreasing their NAcc activity, however, and enhanced control did not persist after subsequent removal of neurofeedback. Further analyses suggested that individuals who recruited positive aroused affect were better able to increase NAcc activity in response to neurofeedback, and that NAcc neurofeedback also elicited functionally correlated activity in the medial prefrontal cortex. Together, these findings suggest that humans can modulate their own NAcc activity and that fMRI-based neurofeedback may augment their efforts. The observed association between positive arousal and effective NAcc control further supports an anticipatory affect account of NAcc function.

  8. Diagnostics and Active Control of Aircraft Interior Noise

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1998-01-01

    This project deals with developing advanced methods for investigating and controlling interior noise in aircraft. The work concentrates on developing and applying the techniques of Near Field Acoustic Holography (NAH) and Principal Component Analysis (PCA) to the aircraft interior noise dynamic problem. This involves investigating the current state of the art, developing new techniques and then applying them to the particular problem being studied. The knowledge gained under the first part of the project was then used to develop and apply new, advanced noise control techniques for reducing interior noise. A new fully active control approach based on the PCA was developed and implemented on a test cylinder. Finally an active-passive approach based on tunable vibration absorbers was to be developed and analytically applied to a range of test structures from simple plates to aircraft fuselages.

  9. Structural vibration control of micro/macro-manipulator using feedforward and feedback approaches

    SciTech Connect

    Lew, J.Y.; Cannon, D.W.; Magee, D.P.; Book, W.J.

    1995-09-01

    Pacific Northwest Laboratory (PDL) researchers investigated the combined use of two control approaches to minimize micro/macro-manipulator structural vibration: (1) modified input shaping and (2) inertial force active damping control. Modified input shaping (MIS) is used as a feedforward controller to modify reference input by canceling the vibratory motion. Inertial force active damping (IFAD) is applied as a feedback controller to increase the system damping and robustness to unexpected disturbances. Researchers implemented both control schemes in the PNL micro/macro flexible-link manipulator testbed collaborating with Georgia Institute of Technology. The experiments successfully demonstrated the effectiveness of two control approaches in reducing structural vibration. Based on the results of the experiments, the combined use of two controllers is recommended for a micro/macro manipulator to achieve the fastest response to commands while canceling disturbances from unexpected forces.

  10. Active vibration control of civil structures

    SciTech Connect

    Farrar, C.; Baker, W.; Fales, J.; Shevitz, D.

    1996-11-01

    This is a final report of a one year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Active vibration control (AVC) of structural and mechanical systems is one of the rapidly advancing areas of engineering research. The multifaceted nature of AVC covers many disciplines, such as sensors and instrumentation, numerical modeling, experimental mechanics, and advanced power systems. This work encompassed a review of the literature on active control of structures focusing both on active control hardware and on control algorithms, a design of an isolation systems using magneto-rheological fluid-filled (MRF) dampers and numerical simulations to study the enhanced vibration mitigation effects of this technology.

  11. Active vibration control of beams using filtered-velocity feedback controllers with moment pair actuators

    NASA Astrophysics Data System (ADS)

    Shin, Changjoo; Hong, Chinsuk; Jeong, Weui Bong

    2013-06-01

    In this study, filtered-velocity feedback (FVF) control is proposed to stabilize a control system with a non-collocated sensor/actuator configuration. This method is applied to actively control a clamped beam with a sensor/moment pair actuator. Since the sensor/moment pair actuator is a non-collocated configuration, the control system experiences structural instability at high frequencies. Due to the roll-off property of the FVF controller, the high frequency structural instability problem can be overcome. Due to the second-order filter characteristics of the FVF controller, similar to a low pass filter, multimode disturbances can be controlled at the modes below the cut-off frequency. To verify the performance of the controller, the FVF controller is tuned to around 2 kHz, and the structural responses are successfully reduced by numerical and experimental approaches.

  12. Active flutter suppression - Control system design and experimental validation

    NASA Technical Reports Server (NTRS)

    Waszak, Martin R.; Srinathkumar, S.

    1991-01-01

    The synthesis and experimental validation of an active flutter suppression controller for the Active Flexible Wing wind-tunnel model is presented. The design is accomplished with traditional root locus and Nyquist methods using interactive computer graphics tools and with extensive use of simulation-based analysis. The design approach uses a fundamental understanding of the flutter mechanism to formulate a simple controller structure to meet stringent design specifications. Experimentally, the flutter suppression controller succeeded in simultaneous suppression of two flutter modes, significantly increasing the flutter dynamic pressure despite errors in flutter dynamic pressure and flutter frequency in the mathematical model. The flutter suppression controller was also successfully operated in combination with a roll maneuver controller to perform flutter suppression during rapid rolling maneuvers.

  13. CFD Modeling for Active Flow Control

    NASA Technical Reports Server (NTRS)

    Buning, Pieter G.

    2001-01-01

    This presentation describes current work under UEET Active Flow Control CFD Research Tool Development. The goal of this work is to develop computational tools for inlet active flow control design. This year s objectives were to perform CFD simulations of fully gridded vane vortex generators, micro-vortex genera- tors, and synthetic jets, and to compare flowfield results with wind tunnel tests of simple geometries with flow control devices. Comparisons are shown for a single micro-vortex generator on a flat plate, and for flow over an expansion ramp with sidewall effects. Vortex core location, pressure gradient and oil flow patterns are compared between experiment and computation. This work lays the groundwork for evaluating simplified modeling of arrays of devices, and provides the opportunity to test simple flow control device/sensor/ control loop interaction.

  14. Active vibration control in microgravity environment

    NASA Technical Reports Server (NTRS)

    Gerhold, Carl H.

    1987-01-01

    The low gravity environment of the space station is suitable for experiments or manufacturing processes which require near zero gravity. An experiment was fabricated to test the validity of the active control process and to verify the flow and control parameters identified in a theoretical model. Zero gravity is approximated in the horizontal plane using a low friction air bearing table. An analog control system was designed to activate calibrated air jets when displacement of the test mass is sensed. The experiment demonstrates that an air jet control system introduces an effective damping factor to control oscillatory response. The amount of damping as well as the flow parameters, such as pressure drop across the valve and flow rate of air, are verified by the analytical model.

  15. Active control of robot manipulator compliance

    NASA Technical Reports Server (NTRS)

    Nguyen, C. C.; Pooran, F. J.

    1986-01-01

    Work performed at Catholic University on the research grant entitled Active Control of Robot Manipulator Compliance, supported by NASA/Goddard space Flight Center during the period of May 15th, 1986 to November 15th, 1986 is described. The modelling of the two-degree-of-freedom robot is first presented. Then the complete system including the robot and the hybrid controller is simulated on an IBM-XT Personal Computer. Simulation results showed that proper adjustments of controller gains enable the robot to perform successful operations. Further research should focus on developing a guideline for the controller gain design to achieve system stability.

  16. Optimal cooperative control synthesis of active displays

    NASA Technical Reports Server (NTRS)

    Garg, S.; Schmidt, D. K.

    1986-01-01

    The utility of augmenting displays to aid the human operator in controlling high order complex systems is well known. Analytical evaluation of various display designs for a simple k/s sup 2 plant in a compensatory tracking task using an optimal Control Model (OCM) of human behavior is carried out. This analysis reveals that significant improvement in performance should be obtained by skillful integration of key information into the display dynamics. The cooperative control synthesis technique previously developed to design pilot-optimal control augmentation is extended to incorporate the simultaneous design of performance enhancing augmented displays. The application of the cooperative control synthesis technique to the design of augmented displays is discussed for the simple k/s sup 2 plant. This technique is intended to provide a systematic approach to design optimally augmented displays tailored for specific tasks.

  17. Optimal cooperative control synthesis of active displays

    NASA Technical Reports Server (NTRS)

    Garg, S.; Schmidt, D. K.

    1985-01-01

    The utility of augmenting displays to aid the human operator in controlling high order complex systems is well known. Analytical evaluations of various display designs for a simple k/s-squared plant in a compensatory tracking task using an Optimal Control Model (OCM) of human behavior is carried out. This analysis reveals that significant improvement in performance should be obtained by skillful integration of key information into the display dynamics. The cooperative control synthesis technique previously developed to design pilot-optimal control augmentation is extended to incorporate the simultaneous design of performance enhancing augmented displays. The application of the cooperative control synthesis technique to the design of augmented displays is discussed for the simple k/s-squared plant. This technique is intended to provide a systematic approach to design optimally augmented displays tailored for specific tasks.

  18. Optimal cooperative control synthesis of active displays

    NASA Technical Reports Server (NTRS)

    Garg, S.; Schmidt, D. K.

    1985-01-01

    A technique is developed that is intended to provide a systematic approach to synthesizing display augmentation for optimal manual control in complex, closed-loop tasks. A cooperative control synthesis technique, previously developed to design pilot-optimal control augmentation for the plant, is extended to incorporate the simultaneous design of performance enhancing displays. The technique utilizes an optimal control model of the man in the loop. It is applied to the design of a quickening control law for a display and a simple K/s(2) plant, and then to an F-15 type aircraft in a multi-channel task. Utilizing the closed loop modeling and analysis procedures, the results from the display design algorithm are evaluated and an analytical validation is performed. Experimental validation is recommended for future efforts.

  19. Optimal cooperative control synthesis of active displays

    NASA Technical Reports Server (NTRS)

    Gary, Sanjay; Schmidt, David K.

    1987-01-01

    A technique is developed that is intended to provide a systematic approach to synthesizing display augmentation for optimal manual control in complex, closed-loop tasks. A cooperative control synthesis technique, previously developed to design pilot-optimal control augmentation for the plant, is extended to incorporate the simultaneous design of performance enhancing displays. The technique utilizes an optimal control model of the man in the loop. It is applied to the design of a quickening control law for a display and a simple K/(s squared) plant, and then to an F-15 type aircraft in a multichannel task. Utilizing the closed-loop modeling and analysis procedures, the results from the display design algorithm are evaluated and an analytical validation is performed. Experimental validation is recommended for future efforts.

  20. Approach to injuries in active people

    PubMed Central

    Shrier, Ian

    2006-01-01

    OBJECTIVE To review the basic principles underlying treatment of injuries in active people. SOURCES OF INFORMATION Basic science texts and reports of observational and randomized trials on treatment of musculoskeletal injuries were retrieved during previous exhaustive systematic reviews published by the author on a variety of musculoskeletal injury topics. MAIN MESSAGE After an injury, further damage or re-injury can be prevented either by decreasing the stress on the tissue or increasing the stress the tissue can withstand. Regardless of the type of injury, clinicians should aim to restore function; aim to increase activity without increasing pain; recommend that patients start slowly and increase activity gradually; revisit diagnosis and treatment if patients are not responding; and treat the patient, not the condition. CONCLUSION Most musculoskeletal injuries in the general population can be managed effectively by family physicians. Management should follow the basic principles of exercise training. PMID:16812964

  1. Digitally Controlled ’Programmable’ Active Filters.

    DTIC Science & Technology

    1985-12-01

    Mitra, S. K., Analysis and Synthesis of Linear Active .. Networks, Wiley, New York, 1969. * 6. Sedra , A. S. and Smith , K. C., "A Second-Generation...Current Conveyor and its Applications," IEEE Trans. Circuit Theory, Vol. CT-17, pp. 132-134, 1970. 7. Sedra , A. S., "A New Approach to Active Network...CT-18, pp. 358-361, May 1971. 27. Hamilton, T. A., and Sedra , A. S., "Some New IJ Configurations for Active Filters," IEEE Trans. Circuit Tehory, Vol

  2. Air Traffic Control/Active Beacon Collision Avoidance System Knoxville Simulation.

    DTIC Science & Technology

    1980-05-01

    Traffic Conditions 3 Error and Response Models 5 Desensitization Methods 5 Data Collection Plan 6 Controller Questionnaires 6 RESULTS AND ANALYSIS 10 ...Operations Rates 10 Effect of Active BCAS on Controllers and Control Procedures 10 Conflict Analysis 10 Active BCAS Protection 13 Active BCAS Alert Rates...Altitude Desensitization 23 10 Encounter on Parallel Approach (Horizontal View) 27 (See Appendix H For Legend) 11 Encounter on Parallel Approach

  3. Wind-Disturbance-Based Control Approach for Blimp Robots

    NASA Astrophysics Data System (ADS)

    Furukawa, Hayato; Shimada, Akira

    Blimps have some advantages, for example, that they do not need driving forces to float and can move in three-dimensional space. However, it is not easy to control them since they are underactuated systems with nonholonomic constraints. Some papers have presented control technologies, but the technologies need impractical conditions. Furukawa et al. presented a blimp control technology by considering a nonholonomic situation, but it cannot be used to control blimps in the presence of wind disturbances. This paper introduces a wind-observer-based control approach that involves the consideration of wind disturbances. A controller based on the proposed approach can generate a driving force in the direction opposite to that of a wind disturbance and help a blimp move against the wind.

  4. Approach to Synchronization Control of Magnetic Bearings Using Fuzzy Logic

    NASA Technical Reports Server (NTRS)

    Yang, Li-Farn

    1996-01-01

    This paper presents a fuzzy-logic approach to the synthesis of synchronization control for magnetically suspended rotor system. The synchronization control enables a whirling rotor to undergo synchronous motion along the magnetic bearing axes; thereby avoiding the gyroscopic effect that degrade the stability of rotor systems when spinning at high speed. The control system features a fuzzy controller acting on the magnetic bearing device, in which the fuzzy inference system trained through fuzzy rules to minimize the differential errors between four bearing axes so that an error along one bearing axis can affect the overall control loop for the motion synchronization. Numerical simulations of synchronization control for the magnetically suspended rotor system are presented to show the effectiveness of the present approach.

  5. A Decentralized Adaptive Approach to Fault Tolerant Flight Control

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva; Nikulin, Vladimir; Heimes, Felix; Shormin, Victor

    2000-01-01

    This paper briefly reports some results of our study on the application of a decentralized adaptive control approach to a 6 DOF nonlinear aircraft model. The simulation results showed the potential of using this approach to achieve fault tolerant control. Based on this observation and some analysis, the paper proposes a multiple channel adaptive control scheme that makes use of the functionally redundant actuating and sensing capabilities in the model, and explains how to implement the scheme to tolerate actuator and sensor failures. The conditions, under which the scheme is applicable, are stated in the paper.

  6. Rotor Flapping Response to Active Control

    NASA Technical Reports Server (NTRS)

    Nguyen, Khanh; Johnson, Wayne

    2004-01-01

    Rotor active control using higher harmonic blade pitch has been proposed as a means to reduce both rotor radiated noise and airframe vibration and to enhance rotor performance. The higher harmonic input, however, can affect rotor thrust and cyclic flapping - the basic trim characteristics of the rotor. Some of the trim changes can negate the active control benefits. For example, wind tunnel test results of a full scale BO-105 rotor with individual-blade control indicate some rotor performance improvements, accompanied with changes in rotor trim, using two-per-rev blade pitch input. The observed performance benefits could therefore be a simple manifestation of the trim change rather than an efficient redistribution of the rotor airloads. More recently, the flight test of the BO-105 helicopter equip,ped with individual-blade-control actuators also reported trim changes whenever the two-per-rev blade pitch for noise reduction was activated. The pilot had to adjust the trim control to maintain the aircraft under a constant flight path. These two cases highlight the, importance of trim considerations in the application of active control to rotorcraft.

  7. Child Development: An Active Learning Approach

    ERIC Educational Resources Information Center

    Levine, Laura E.; Munsch, Joyce

    2010-01-01

    Within each chapter of this innovative topical text, the authors engage students by demonstrating the wide range of real-world applications of psychological research connected to child development. In particular, the distinctive Active Learning features incorporated throughout the book foster a dynamic and personal learning process for students.…

  8. Personalized approaches to active immunotherapy in cancer.

    PubMed

    Ophir, Eran; Bobisse, Sara; Coukos, George; Harari, Alexandre; Kandalaft, Lana E

    2016-01-01

    Immunotherapy is emerging as a promising anti-cancer curative modality. However, in contrast to recent advances obtained employing checkpoint blockade agents and T cell therapies, clinical efficacy of therapeutic cancer vaccines is still limited. Most vaccination attempts in the clinic represent "off-the shelf" approaches since they target common "self" tumor antigens, shared among different patients. In contrast, personalized approaches of vaccination are tailor-made for each patient and in spite being laborious, hold great potential. Recent technical advancement enabled the first steps in the clinic of personalized vaccines that target patient-specific mutated neo-antigens. Such vaccines could induce enhanced tumor-specific immune response since neo-antigens are mutation-derived antigens that can be recognized by high affinity T cells, not limited by central tolerance. Alternatively, the use of personalized vaccines based on whole autologous tumor cells, overcome the need for the identification of specific tumor antigens. Whole autologous tumor cells could be administered alone, pulsed on dendritic cells as lysate, DNA, RNA or delivered to dendritic cells in-vivo through encapsulation in nanoparticle vehicles. Such vaccines may provide a source for the full repertoire of the patient-specific tumor antigens, including its private neo-antigens. Furthermore, combining next-generation personalized vaccination with other immunotherapy modalities might be the key for achieving significant therapeutic outcome.

  9. Actively controlled shaft seals for aerospace applications

    NASA Technical Reports Server (NTRS)

    Salant, Richard F.

    1994-01-01

    This study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100 C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changed suddenly.

  10. Improving active space telescope wavefront control using predictive thermal modeling

    NASA Astrophysics Data System (ADS)

    Gersh-Range, Jessica; Perrin, Marshall D.

    2015-01-01

    Active control algorithms for space telescopes are less mature than those for large ground telescopes due to differences in the wavefront control problems. Active wavefront control for space telescopes at L2, such as the James Webb Space Telescope (JWST), requires weighing control costs against the benefits of correcting wavefront perturbations that are a predictable byproduct of the observing schedule, which is known and determined in advance. To improve the control algorithms for these telescopes, we have developed a model that calculates the temperature and wavefront evolution during a hypothetical mission, assuming the dominant wavefront perturbations are due to changes in the spacecraft attitude with respect to the sun. Using this model, we show that the wavefront can be controlled passively by introducing scheduling constraints that limit the allowable attitudes for an observation based on the observation duration and the mean telescope temperature. We also describe the implementation of a predictive controller designed to prevent the wavefront error (WFE) from exceeding a desired threshold. This controller outperforms simpler algorithms even with substantial model error, achieving a lower WFE without requiring significantly more corrections. Consequently, predictive wavefront control based on known spacecraft attitude plans is a promising approach for JWST and other future active space observatories.

  11. Vector control activities. Fiscal year, 1982

    SciTech Connect

    Pickard, E.; Cooney, J.C.; McDuff, B.R.

    1983-06-01

    The goal of the TVA Vector Control Program is to protect the public from potential vectors of disease by controlling medically-important arthropod pests that are propagated on TVA lands or waters. In addition, freedom from annoying mosquitoes and other blood-sucking pests permits the development, use, and full enjoyment of the vast recreational opportunities offered by the many miles of freshwater lakes. To attain this goal the program is divided into operations and support studies. The support studies are designed to improve the operational effectiveness and efficiency of the control program and to identify other vector control problems that require TVA attention and study. Specifically, activities concerning water level management of TVA lakes, dewatering projects, plant growth control, drainage and insect control programs are detailed. Further, report is made of post-impoundment surveys, soil sampling studies of Mosquite larvae and ecological mosquito management studies.

  12. Smart actuators for active vibration control

    NASA Astrophysics Data System (ADS)

    Pourboghrat, Farzad; Daneshdoost, Morteza

    1998-07-01

    In this paper, the design and implementation of smart actuators for active vibration control of mechanical systems are considered. A smart actuator is composed of one or several layers of piezo-electric materials which work both as sensors and actuators. Such a system also includes micro- electronic or power electronic amplifiers, depending on the power requirements and applications, as well as digital signal processing systems for digital control implementation. In addition, PWM type micro/power amplifiers are used for control implementation. Such amplifiers utilize electronic switching components that allow for miniaturization, thermal efficiency, cost reduction, and precision controls that are robust to disturbances and modeling errors. An adaptive control strategy is then developed for vibration damping and motion control of cantilever beams using the proposed smart self-sensing actuators.

  13. Actively Controlling Buffet-Induced Excitations

    NASA Technical Reports Server (NTRS)

    Moses, Robert W.; Pototzky, Anthony S.; Henderson, Douglas A.; Galea, Stephen C.; Manokaran, Donald S.; Zimcik, David G.; Wickramasinghe, Viresh; Pitt, Dale M.; Gamble, Michael A.

    2005-01-01

    High performance aircraft, especially those with twin vertical tails, encounter unsteady buffet loads when flying at high angles of attack. These loads result in significant random stresses, which may cause fatigue damage leading to restricted capabilities and availability of the aircraft. An international collaborative research activity among Australia, Canada and the United States, conducted under the auspices of The Technical Cooperation Program (TTCP) contributed resources toward a program that coalesced a broad range of technical knowledge and expertise into a single investigation to demonstrate the enhanced performance and capability of the advanced active BLA control system in preparation for a flight test demonstration. The research team investigated the use of active structural control to alleviate the damaging structural response to these loads by applying advanced directional piezoelectric actuators, the aircraft rudder, switch mode amplifiers, and advanced control strategies on an F/A-18 aircraft empennage. Some results of the full-scale investigation are presented herein.

  14. Active Flow Control Stator With Coanda Surface

    NASA Technical Reports Server (NTRS)

    Guendogdu; Vorreiter; Seume

    2010-01-01

    Active Flow Control increases the permissible aerodynamic loading. Curved surface near the trailing edge ("Coanda surface"): a) increases turning -> higher pressure ratio. b) controls boundary layer separation -> increased surge margin. Objective: Reduce the number of vanes or compressor stages. Constraints: 1. In a real compressor, the vane must still function entirely without blowing. 2. Maintain the flow exit angle of the reference stator despite the resulting increase in stator loading.

  15. Feasibility of Automated Adaptive GCA (Ground Controlled Approach) Controller Training System.

    ERIC Educational Resources Information Center

    Feuge, Robert L.; And Others

    An analysis of the conceptual feasibility of using automatic speech recognition and understanding technology in the design of an advanced training system was conducted. The analysis specifically explored application to Ground Controlled Approach (GCA) controller training. A systems engineering approach was followed to determine the feasibility of…

  16. Active Control Evaluation for Spacecraft (ACES)

    NASA Technical Reports Server (NTRS)

    Pearson, J.; Yuen, W.

    1986-01-01

    The Air Force goal is to develop vibration control techniques for large flexible spacecraft by addressing sensor, actuator, and control hardware and dynamic testing. The Active Control Evaluation for Spacecraft (ACES) program will address the Air Force goal by looking at two leading control techniques and implementing them on a structural model of a flexible spacecraft under laboratory testing. The first phase in the ACES program is to review and to assess the High Authority Control/Low Authority Control (HAC/LAC) and Filter accomodated Model Error Sensitivity Suppression (FAMESS) control techniques for testing on the modified VCOSS structure. Appropriate sensors and actuators will be available for use with both techniques; locations will be the same for both techniques. The control actuators will be positioned at the midpoint and free end of the structure. The laser source for the optical sensor is mounted on the feed mast. The beam will be reflected from a mirror on the offset antenna onto the detectors mounted above the shaker table bay. The next phase is to develop an analysis simulation with the control algorithms implemented for dynamics verification. The third phase is to convert the control laws into high level computer language and test them in the NASA-MSFC facility. The final phase is to compile all analytical and test results for performance comparisons.

  17. Stochastic Control of Energy Efficient Buildings: A Semidefinite Programming Approach

    SciTech Connect

    Ma, Xiao; Dong, Jin; Djouadi, Seddik M; Nutaro, James J; Kuruganti, Teja

    2015-01-01

    The key goal in energy efficient buildings is to reduce energy consumption of Heating, Ventilation, and Air- Conditioning (HVAC) systems while maintaining a comfortable temperature and humidity in the building. This paper proposes a novel stochastic control approach for achieving joint performance and power control of HVAC. We employ a constrained Stochastic Linear Quadratic Control (cSLQC) by minimizing a quadratic cost function with a disturbance assumed to be Gaussian. The problem is formulated to minimize the expected cost subject to a linear constraint and a probabilistic constraint. By using cSLQC, the problem is reduced to a semidefinite optimization problem, where the optimal control can be computed efficiently by Semidefinite programming (SDP). Simulation results are provided to demonstrate the effectiveness and power efficiency by utilizing the proposed control approach.

  18. An active learning approach to Bloom's Taxonomy.

    PubMed

    Weigel, Fred K; Bonica, Mark

    2014-01-01

    As educators strive toward improving student learning outcomes, many find it difficult to instill their students with a deep understanding of the material the instructors share. One challenge lies in how to provide the material with a meaningful and engaging method that maximizes student understanding and synthesis. By following a simple strategy involving Active Learning across the 3 primary domains of Bloom's Taxonomy (cognitive, affective, and psychomotor), instructors can dramatically improve the quality of the lesson and help students retain and understand the information. By applying our strategy, instructors can engage their students at a deeper level and may even find themselves enjoying the process more.

  19. Active Control of Cryogenic Propellants in Space

    NASA Technical Reports Server (NTRS)

    Notardonato, William

    2011-01-01

    A new era of space exploration is being planned. Exploration architectures under consideration require the long term storage of cryogenic propellants in space. This requires development of active control systems to mitigate the effect of heat leak. This work summarizes current state of the art, proposes operational design strategies and presents options for future architectures. Scaling and integration of active systems will be estimated. Ideal long range spacecraft systems will be proposed with Exploration architecture benefits considered.

  20. Overview of Active Flow Control at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Pack, L. G.; Joslin, R. D.

    1998-01-01

    The paper summarizes Active Flow Control projects currently underway at the NASA Langley Research Center. Technology development is being pursued within a multidisciplinary, cooperative approach, involving the classical disciplines of fluid mechanics, structural mechanics, material science, acoustics, and stability and control theory. Complementing the companion papers in this session, the present paper will focus on projects that have the goal of extending the state-of-the-art in the measurement, prediction, and control of unsteady, nonlinear aerodynamics. Toward this goal, innovative actuators, micro and macro sensors, and control strategies are considered for high payoff flow control applications. The target payoffs are outlined within each section below. Validation of the approaches range from bench-top experiments to wind-tunnel experiments to flight tests. Obtaining correlations for future actuator and sensor designs are implicit in the discussion. The products of the demonstration projects and design tool development from the fundamental NASA R&D level technology will then be transferred to the Applied Research components within NASA, DOD, and US Industry. Keywords: active flow control, separation control, MEMS, review

  1. Seismic active control by neutral networks

    SciTech Connect

    Tang, Yu

    1995-12-31

    A study on the application of artificial neural networks (ANNs) to active structural control under seismic loads is carried out. The structure considered is a single-degree-of-freedom (SDF) system with an active bracing device. The control force is computed by a trained neural network. The feedforward neural network architecture and an adaptive backpropagation training algorithm is used in the study. The neural net is trained to reproduce the function that represents the response-excitation relationship of the SDF system under seismic loads. The input-output training patterns are generated randomly. In the backpropagation training algorithm, the learning rate is determined by ensuring the decrease of the error function at each epoch. The computer program implemented is validated by solving the classification of the XOR problem. Then, the trained ANN is used to compute the control force according to the control strategy. If the control force exceeds the actuator`s capacity limit, it is set equal to that limit. The concept of the control strategy employed herein is to apply the control force at every time step to cancel the system velocity induced at the preceding time step so that the gradual rhythmic buildup of the response is destroyed. The ground motions considered in the numerical example are the 1940 El Centro earthquake and the 1979 Imperial Valley earthquake in California. The system responses with and without the control are calculated and compared. The feasibility and potential of applying ANNs to seismic active control is asserted by the promising results obtained from the numerical examples studied.

  2. Strain-optic active control for quantum integrated photonics.

    PubMed

    Humphreys, Peter C; Metcalf, Benjamin J; Spring, Justin B; Moore, Merritt; Salter, Patrick S; Booth, Martin J; Steven Kolthammer, W; Walmsley, Ian A

    2014-09-08

    We present a practical method for active phase control on a photonic chip that has immediate applications in quantum photonics. Our approach uses strain-optic modification of the refractive index of individual waveguides, effected by a millimeter-scale mechanical actuator. The resulting phase change of propagating optical fields is rapid and polarization-dependent, enabling quantum applications that require active control and polarization encoding. We demonstrate strain-optic control of non-classical states of light in silica, showing the generation of 2-photon polarisation N00N states by manipulating Hong-Ou-Mandel interference. We also demonstrate switching times of a few microseconds, which are sufficient for silica-based feed-forward control of photonic quantum states.

  3. O the Use of Modern Control Theory for Active Structural Acoustic Control.

    NASA Astrophysics Data System (ADS)

    Saunders, William Richard

    A modern control theory formulation of Active Structural Acoustic Control (ASAC) of simple structures radiating acoustic energy into light or heavy fluid mediums is discussed in this dissertation. ASAC of a baffled, simply-supported plate subject to mechanical disturbances is investigated. For the case of light fluid loading, a finite element modelling approach is used to extend previous ASAC design methods. Vibration and acoustic controllers are designed for the plate. Comparison of the controller performance shows distinct advantages of the ASAC method for minimizing radiated acoustic power. A novel approach to the modelling of the heavy fluid-loaded plate is developed here. Augmenting structural and acoustic dynamics using state vector formalism allows the design of both vibration and ASAC controllers for the fluid-loaded plate. This modern control approach to active structural acoustic control is unique in its ability to suppress both persistent and transient disturbances on a plate in a heavy fluid. Numerical simulations of the open-loop and closed-loop plate response are provided to support the theoretical developments.

  4. [The Hazard Analysis Critical Control Point approach (HACCP) in meat production].

    PubMed

    Berends, B R; Snijders, J M

    1994-06-15

    The Hazard Analysis Critical Control Point (HACCP) approach is a method that could transform the current system of safety and quality assurance of meat into a really effective and flexible integrated control system. This article discusses the origin and the basic principles of the HACCP approach. It also discusses why the implementation of the approach is not as widespread as might be expected. It is concluded that a future implementation of the approach in the entire chain of meat production, i.e. from conception to consumption, is possible. Prerequisites are, however, that scientifically validated risk analyses become available, that future legislation forms a framework that actively supports the approach, and that all parties involved in meat production not only become convinced of the advantages, but also are trained to implement the HACCP approach with insight.

  5. Nanorobotics control design: a collective behavior approach for medicine

    NASA Astrophysics Data System (ADS)

    Cavalcanti, A.; Freitas, R. A., Jr.

    2005-06-01

    The authors present a new approach using genetic algorithms, neural networks, and nanorobotics concepts applied to the problem of control design for nanoassembly automation and its application in medicine. As a practical approach to validate the proposed design, we have elaborated and simulated a virtual environment focused on control automation for nanorobotics teams that exhibit collective behavior. This collective behavior is a suitable way to perform a large range of tasks and positional assembly manipulation in a complex three-dimensional workspace. We emphasize the application of such techniques as a feasible approach for the investigation of nanorobotics system design in nanomedicine. Theoretical and practical analyses of control modeling is one important aspect that will enable rapid development in the emerging field of nanotechnology.

  6. Enhancing Sensorimotor Activity by Controlling Virtual Objects with Gaze

    PubMed Central

    Modroño, Cristián; Plata-Bello, Julio; Zelaya, Fernando; García, Sofía; Galván, Iván; Marcano, Francisco; Navarrete, Gorka; Casanova, Óscar; Mas, Manuel; González-Mora, José Luis

    2015-01-01

    This fMRI work studies brain activity of healthy volunteers who manipulated a virtual object in the context of a digital game by applying two different control methods: using their right hand or using their gaze. The results show extended activations in sensorimotor areas, not only when participants played in the traditional way (using their hand) but also when they used their gaze to control the virtual object. Furthermore, with the exception of the primary motor cortex, regional motor activity was similar regardless of what the effector was: the arm or the eye. These results have a potential application in the field of the neurorehabilitation as a new approach to generate activation of the sensorimotor system to support the recovery of the motor functions. PMID:25799431

  7. Piezoelectric Power Requirements for Active Vibration Control

    NASA Technical Reports Server (NTRS)

    Brennan, Matthew C.; McGowan, Anna-Maria Rivas

    1997-01-01

    This paper presents a method for predicting the power consumption of piezoelectric actuators utilized for active vibration control. Analytical developments and experimental tests show that the maximum power required to control a structure using surface-bonded piezoelectric actuators is independent of the dynamics between the piezoelectric actuator and the host structure. The results demonstrate that for a perfectly-controlled system, the power consumption is a function of the quantity and type of piezoelectric actuators and the voltage and frequency of the control law output signal. Furthermore, as control effectiveness decreases, the power consumption of the piezoelectric actuators decreases. In addition, experimental results revealed a non-linear behavior in the material properties of piezoelectric actuators. The material non- linearity displayed a significant increase in capacitance with an increase in excitation voltage. Tests show that if the non-linearity of the capacitance was accounted for, a conservative estimate of the power can easily be determined.

  8. Closed-loop active optical system control

    NASA Astrophysics Data System (ADS)

    Sparks, T. E.

    1980-01-01

    A control system, based on a real-time lateral shear interferometer has been developed for use in control during thermal tests and static error compensation experiments. The minicomputer which controls the interferometer and provides its service functions also controls the active system, thereby giving flexibility to the algorithm. The minicomputer system contains 288 K bytes of memory and 15 M bytes of disk storage. The interferometer system employed is composed of the measuring head and its support electronics, a video display on which wavefront contour maps are generated, and a DECwriter operator console. The versatility provided by the use of a general purpose interferometer system allows for interactive control of the closed-loop process. Various arithmetic capabilities such as the addition of wavefronts, division by a constant, and fitting of wavefront data with Zernike polynomials, allow for measurements to be averaged and for removal of alignment errors before correction is performed.

  9. Actively Controlled Shaft Seals for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Salant, Richard F.; Wolff, Paul

    1995-01-01

    This study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with a piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changes suddenly. the experimental results were compared to the predictions from the mathematical model. The model was successful in predicting the trends in leakage rate that occurred as the balance ratio and sealed pressure changed

  10. Actively controlled shaft seals for aerospace applications

    NASA Astrophysics Data System (ADS)

    Salant, Richard F.

    1995-07-01

    This study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with a piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changes suddenly. the experimental results were compared to the predictions from the mathematical model. The model was successful in predicting the trends in leakage rate that occurred as the balance ratio and sealed pressure changed

  11. Can Physical Education and Physical Activity Outcomes Be Developed Simultaneously Using a Game-Centered Approach?

    ERIC Educational Resources Information Center

    Miller, Andrew; Christensen, Erin; Eather, Narelle; Gray, Shirley; Sproule, John; Keay, Jeanne; Lubans, David

    2016-01-01

    The primary objective of this study was to evaluate the efficacy of a pilot intervention using a game-centered approach for improvement of physical activity (PA) and physical education (PE) outcomes simultaneously, and if this had an impact on enjoyment of PE. A group-randomized controlled trial with a 7-week wait-list control group was conducted…

  12. A variable structure approach to robust control of VTOL aircraft

    NASA Technical Reports Server (NTRS)

    Calise, A. J.; Kramer, F.

    1982-01-01

    This paper examines the application of variable structure control theory to the design of a flight control system for the AV-8A Harrier in a hover mode. The objective in variable structure design is to confine the motion to a subspace of the total state space. The motion in this subspace is insensitive to system parameter variations and external disturbances that lie in the range space of the control. A switching type of control law results from the design procedure. The control system was designed to track a vector velocity command defined in the body frame. For comparison purposes, a proportional controller was designed using optimal linear regulator theory. Both control designs were first evaluated for transient response performance using a linearized model, then a nonlinear simulation study of a hovering approach to landing was conducted. Wind turbulence was modeled using a 1052 destroyer class air wake model.

  13. Active control of fan noise from a turbofan engine

    NASA Technical Reports Server (NTRS)

    Thomas, Russell H.; Burdisso, Ricardo A.; Fuller, Christopher R.; O'Brien, Walter F.

    1994-01-01

    A three-channel active control system is applied to an operational turbofan engine to reduce tonal noise produced by both the fan and the high-pressure compressor. The control approach is the feedforward filtered-x least-mean-square algorithm implemented on a digital signal processing board. Reference transducers mounted on the engine case provide blade passing and harmonics frequency information to the controller. Error information is provided by large area microphones placed in the acoustic far field. To minimize the error signal, the controller actuates loudspeakers mounted on the inlet to produce destructive interference. The sound pressure level of the fundamental tone of the fan was reduced using the three-channel controller by up to 16 dB over a +/- 30-deg angle about the engine axis. A single-channel controller could produce reduction over a +/- 15-deg angle. The experimental results show the control to be robust. Outside of the areas contolled, the levels of the tone actually increased due to the generation of radial modes by the control sources. Simultaneous control of two tones is achieved with parallel controllers. The fundamental and the first harmonic tones of the fan were controlled simultaneously with reductions of 12 and 5 dBA, respectively, measured on the engine axis. Simultaneous control was also demonstrated for the fan fundamental and the high-pressure compressor fundamental tones.

  14. MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON

    EPA Science Inventory

    The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

  15. DNA-based control of protein activity

    PubMed Central

    Engelen, W.; Janssen, B. M. G.

    2016-01-01

    DNA has emerged as a highly versatile construction material for nanometer-sized structures and sophisticated molecular machines and circuits. The successful application of nucleic acid based systems greatly relies on their ability to autonomously sense and act on their environment. In this feature article, the development of DNA-based strategies to dynamically control protein activity via oligonucleotide triggers is discussed. Depending on the desired application, protein activity can be controlled by directly conjugating them to an oligonucleotide handle, or expressing them as a fusion protein with DNA binding motifs. To control proteins without modifying them chemically or genetically, multivalent ligands and aptamers that reversibly inhibit their function provide valuable tools to regulate proteins in a noncovalent manner. The goal of this feature article is to give an overview of strategies developed to control protein activity via oligonucleotide-based triggers, as well as hurdles yet to be taken to obtain fully autonomous systems that interrogate, process and act on their environments by means of DNA-based protein control. PMID:26812623

  16. Active Noise Control for Dishwasher noise

    NASA Astrophysics Data System (ADS)

    Lee, Nokhaeng; Park, Youngjin

    2016-09-01

    The dishwasher is a useful home appliance and continually used for automatically washing dishes. It's commonly placed in the kitchen with built-in style for practicality and better use of space. In this environment, people are easily exposed to dishwasher noise, so it is an important issue for the consumers, especially for the people living in open and narrow space. Recently, the sound power levels of the noise are about 40 - 50 dBA. It could be achieved by removal of noise sources and passive means of insulating acoustical path. For more reduction, such a quiet mode with the lower speed of cycle has been introduced, but this deteriorates the washing capacity. Under this background, we propose active noise control for dishwasher noise. It is observed that the noise is propagating mainly from the lower part of the front side. Control speakers are placed in the part for the collocation. Observation part of estimating sound field distribution and control part of generating the anti-noise are designed for active noise control. Simulation result shows proposed active noise control scheme could have a potential application for dishwasher noise reduction.

  17. A new approach to global control of redundant manipulators

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun

    1989-01-01

    A new and simple approach to configuration control of redundant manipulators is presented. In this approach, the redundancy is utilized to control the manipulator configuration directly in task space, where the task will be performed. A number of kinematic functions are defined to reflect the desirable configuration that will be achieved for a given end-effector position. The user-defined kinematic functions and the end-effector Cartesian coordinates are combined to form a set of task-related configuration variables as generalized coordinates for the manipulator. An adaptive scheme is then utilized to globally control the configuration variables so as to achieve tracking of some desired reference trajectories. This accomplishes the basic task of desired end-effector motion, while utilizing the redundancy to achieve any additional task through the desired time variation of the kinematic functions. The control law is simple and computationally very fast, and does not require the complex manipulator dynamic model.

  18. Active control of multiple resistive wall modes

    NASA Astrophysics Data System (ADS)

    Brunsell, P. R.; Yadikin, D.; Gregoratto, D.; Paccagnella, R.; Liu, Y. Q.; Bolzonella, T.; Cecconello, M.; Drake, J. R.; Kuldkepp, M.; Manduchi, G.; Marchiori, G.; Marrelli, L.; Martin, P.; Menmuir, S.; Ortolani, S.; Rachlew, E.; Spizzo, G.; Zanca, P.

    2005-12-01

    A two-dimensional array of saddle coils at Mc poloidal and Nc toroidal positions is used on the EXTRAP T2R reversed-field pinch (Brunsell P R et al 2001 Plasma Phys. Control. Fusion 43 1457) to study active control of resistive wall modes (RWMs). Spontaneous growth of several RWMs with poloidal mode number m = 1 and different toroidal mode number n is observed experimentally, in agreement with linear MHD modelling. The measured plasma response to a controlled coil field and the plasma response computed using the linear circular cylinder MHD model are in quantitive agreement. Feedback control introduces a linear coupling of modes with toroidal mode numbers n, n' that fulfil the condition |n - n'| = Nc. Pairs of coupled unstable RWMs are present in feedback experiments with an array of Mc × Nc = 4 × 16 coils. Using intelligent shell feedback, the coupled modes are generally not controlled even though the field is suppressed at the active coils. A better suppression of coupled modes may be achieved in the case of rotating modes by using the mode control feedback scheme with individually set complex gains. In feedback with a larger array of Mc × Nc = 4 × 32 coils, the coupling effect largely disappears, and with this array, the main internal RWMs n = -11, -10, +5, +6 are all simultaneously suppressed throughout the discharge (7 8 wall times). With feedback there is a two-fold extension of the pulse length, compared to discharges without feedback.

  19. Space shuttle active-pogo-suppressor control design using linear quadratic regulator techniques

    NASA Technical Reports Server (NTRS)

    Lehtinen, B.; Lorenz, C. F.

    1979-01-01

    Two methods of active pogo suppression (stabilization) for the space shuttle vehicle were studied analytically. The basis for both approaches was the linear quadratic regulator, state space technique. The first approach minimized root-mean-square pump inlet pressure by using either fullstate feedback, partial-state feedback, or output feedback with a Kalman filter. The second approach increased the modal damping associated with the critical structural modes by using either full-state feedback or reconstructed state feedback. A number of implementable controls were found by both approaches. The designs were analyzed with respect to sensitivity, complexity, and controller energy requirements, as well as controller performance. Practical controllers resulting from the two design approaches tended to use pressure and flow as feedback variables for the minimum-rms method and structural accelerations or velocities for the modal control method. Both approaches are suitable for the design of active pogo-suppression controllers.

  20. Modeling and Control for an Asymmetric Hydraulic Active Suspension System

    NASA Astrophysics Data System (ADS)

    Kim, Wanil; Won, Sangchul

    In this paper we present a model for an automotive active suspension system which includes the dynamics of an asymmetric hydraulic actuator. In this model the force exerted by a single-rod cylinder is regarded as an internal state, and the sum of the oil flow rates through the orifice of a servo valve as the control input. We obtain a linear time-invariant (LTI) state state equation and propose a force-tracking-free one-step control method which can accept various linear control techniques. An optimal state-feedback control is applied as an example. Quarter car test rig experiment results show the effectiveness of the proposed approach in modeling and control.

  1. A control theory approach to clock steering techniques.

    PubMed

    Farina, Marcello; Galleani, Lorenzo; Tavella, Patrizia; Bittanti, Sergio

    2010-10-01

    Several clock and time scale steering methods have been developed according to different viewpoints by various time laboratories. By resorting to control theory ideas, we propose a common theoretical framework encompassing these methods. A comparison of the most common steering methodologies, namely, the classical steering approach, the GPS bang-bang method, and the linear quadratic Gaussian technique, is carried out. We believe that the use of control theory methods can potentially lead to a better understanding of clock steering algorithms.

  2. Understanding Fatty Acid Metabolism through an Active Learning Approach

    ERIC Educational Resources Information Center

    Fardilha, M.; Schrader, M.; da Cruz e Silva, O. A. B.; da Cruz e Silva, E. F.

    2010-01-01

    A multi-method active learning approach (MALA) was implemented in the Medical Biochemistry teaching unit of the Biomedical Sciences degree at the University of Aveiro, using problem-based learning as the main learning approach. In this type of learning strategy, students are involved beyond the mere exercise of being taught by listening. Less…

  3. Using behavioural activation in the treatment of depression: a control theory perspective.

    PubMed

    McEvoy, P; Law, A; Bates, R; Hylton, K; Mansell, W

    2013-12-01

    Behavioural activation is an intervention that can be used to counteract the typical patterns of withdrawal, avoidance and inactivity that characterize depression. This paper examines the processes of change that may occur during behavioural activation from the perspective of control theory. Some of the key concepts that are associated with control theory are introduced and the process of change that may occur during behavioural activation is illustrated using two case studies. The case studies provide anecdotal evidence which supports the hypothesis that the effective implementation of behavioural activation may depend upon clients being able to retain or regain the sense of control that they value. The differences between a control-theory-based approach and more orthodox behavioural and cognitive approaches are highlighted and the implications of these differences are discussed. Flexible approaches that are informed by control theory, may offer a useful alternative to the more established behavioural and cognitive approaches towards behavioural activation.

  4. Active control of fan noise from a turbofan engine

    NASA Technical Reports Server (NTRS)

    Thomas, Russell H.; Burdisso, Ricardo A.; Fuller, Christopher R.; O'Brien, Walter F.

    1993-01-01

    A three channel active control system is applied to an operational turbofan engine in order to reduce tonal noise produced by both the fan and high pressure compressor. The control approach is the feedforward filtered-x least-mean-square algorithm implemented on a digital signal processing board. Reference transducers mounted on the engine case provides blade passing and harmonics frequency information to the controller. Error information is provided by large area microphones placed in the acoustic far field. In order to minimize the error signal, the controller actuates loudspeakers mounted on the inlet to produce destructive interference. The sound pressure level of the fundamental tone of the fan was reduced using the three channel controller by up to 16 dB over a 60 deg angle about the engine axis. A single channel controller could produce reduction over a 30 deg angle. The experimental results show the control to be robust. Simultaneous control of two tones is done with parallel controllers. The fundamental and the first harmonic tones of the fan were controlled simultaneously with reductions of 12 dBA and 5 dBA, respectively, measured on the engine axis. Simultaneous control was also demonstrated for the fan fundamental and the high pressure compressor fundamental tones.

  5. Control Systems Cyber Security Standards Support Activities

    SciTech Connect

    Robert Evans

    2009-01-01

    The Department of Homeland Security’s Control Systems Security Program (CSSP) is working with industry to secure critical infrastructure sectors from cyber intrusions that could compromise control systems. This document describes CSSP’s current activities with industry organizations in developing cyber security standards for control systems. In addition, it summarizes the standards work being conducted by organizations within the sector and provides a brief listing of sector meetings and conferences that might be of interest for each sector. Control systems cyber security standards are part of a rapidly changing environment. The participation of CSSP in the development effort for these standards has provided consistency in the technical content of the standards while ensuring that information developed by CSSP is included.

  6. Actively controlled vibration welding system and method

    DOEpatents

    Cai, Wayne W.; Kang, Bongsu; Tan, Chin-An

    2013-04-02

    A vibration welding system includes a controller, welding horn, an active material element, and anvil assembly. The assembly may include an anvil body connected to a back plate and support member. The element, e.g., a piezoelectric stack or shape memory alloy, is positioned with respect to the assembly. The horn vibrates in a desirable first direction to form a weld on a work piece. The element controls any vibrations in a second direction by applying calibrated response to the anvil body in the second direction. A method for controlling undesirable vibrations in the system includes positioning the element with respect to the anvil assembly, connecting the anvil body to the support member through the back plate, vibrating the horn in a desirable first direction, and transmitting an input signal to the element to control vibration in an undesirable second direction.

  7. Activity, activity, activity: rethinking our physical therapy approach to cerebral palsy.

    PubMed

    Damiano, Diane L

    2006-11-01

    This perspective outlines the theoretical basis for the presentation with the same name as the second part of this title, which was given at the III STEP conference in July 2005. It elaborates on the take-home message from that talk, which was to promote activity in children and adults with cerebral palsy and other central nervous system disorders. The author proposes that the paradigm for physical therapist management of cerebral palsy needs to shift from traditional or "packaged" approaches to a more focused and proactive approach of promoting activity through more intense active training protocols, lifestyle modifications, and mobility-enhancing devices. Increased motor activity has been shown to lead to better physical and mental health and to augment other aspects of functioning such as cognitive performance, and more recently has been shown to promote neural and functional recovery in people with damaged nervous systems. Although the benefits of fairly intense physical exercise programs such as strength training are becoming increasingly well recognized, few studies on the positive effects of generalized activity programs have been conducted in individuals with cerebral palsy. More research is needed and is currently under way to design and test the efficacy of activity-based strategies in cerebral palsy.

  8. Air pollution exposure: An activity pattern approach for active transportation

    NASA Astrophysics Data System (ADS)

    Adams, Matthew D.; Yiannakoulias, Nikolaos; Kanaroglou, Pavlos S.

    2016-09-01

    In this paper, we demonstrate the calculation of personal air pollution exposure during trips made by active transportation using activity patterns without personal monitors. We calculate exposure as the inhaled dose of particulate matter 2.5 μg or smaller. Two modes of active transportation are compared, and they include cycling and walking. Ambient conditions are calculated by combining mobile and stationary monitoring data in an artificial neural network space-time model. The model uses a land use regression framework and has a prediction accuracy of R2 = 0.78. Exposure is calculated at 10 m or shorter intervals during the trips using inhalation rates associated with both modes. The trips are children's routes between home and school. The average dose during morning cycling trips was 2.17 μg, during morning walking trips was 3.19 μg, during afternoon cycling trips was 2.19 μg and during afternoon walking trips was 3.23 μg. The cycling trip dose was significantly lower than the walking trip dose. The air pollution exposure during walking or cycling trips could not be strongly predicted by either the school or household ambient conditions, either individually or in combination. Multiple linear regression models regressing both the household and school ambient conditions against the dose were only able to account for, at most, six percent of the variance in the exposure. This paper demonstrates that incorporating activity patterns when calculating exposure can improve the estimate of exposure compared to its calculation from ambient conditions.

  9. Improved clipped periodic optimal control for semi-active harmonic disturbance rejection

    NASA Astrophysics Data System (ADS)

    Couillard, Maxime; Micheau, Philippe; Masson, Patrice

    2008-12-01

    This paper presents a new approach for harmonic disturbance rejection using semi-active vibration control. The approach is illustrated through application to the problem of maximizing the energy dissipated by a semi-active damper under harmonic excitation. In order to establish a baseline for the evaluation of the performance of the semi-active damper, the effectiveness of the optimal passive and active cases are first presented. The study then examines the ability of the clipped optimal control (or clipping control) approach to improve the energy dissipation capacity of the semi-active damper over the optimal passive damper. An approximate solution to the nonlinear dynamic problem, obtained using the method of averaging, and a time integration based numerical method indicate that this approach improves the energy dissipated by the semi-active damper over the optimal passive damper. The approach presented in this paper intends to further "improve", or "fine tune", the control parameters given by the clipped optimal control approach. This is done using an approximated solution of the problem and an appropriate optimization algorithm. Results clearly indicate that this new approach provides significant improvement on energy dissipation over the clipped optimal control approach for the semi-active damper.

  10. Active vibration control using DEAP actuators

    NASA Astrophysics Data System (ADS)

    Sarban, Rahimullah; Jones, Richard W.

    2010-04-01

    Dielectric electro-active polymer (DEAP) is a new type of smart material, which has the potential to be used to provide effective actuation for a wide range of applications. The properties of DEAP material place it somewhere between those of piezoceramics and shape memory alloys. Of the range of DEAP-based actuators that have been developed those having a cylindrical configuration are among the most promising. This contribution introduces the use of a tubular type DEAP actuator for active vibration control purposes. Initially the DEAP-based tubular actuator to be used in this study, produced by Danfoss PolyPower A/S, is introduced along with the static and dynamic characteristics. Secondly an electromechanical model of the tubular actuator is briefly reviewed and its ability to model the actuator's hysteresis characteristics for a range of periodic input signals at different frequencies demonstrated. The model will be used to provide hysteresis compensation in future vibration isolation studies. Experimental active vibration control using the actuator is then examined, specifically active vibration isolation of a 250 g mass subject to shaker generated 'ground vibration'. An adaptive feedforward control strategy is used to achieve this. The ability of the tubular actuator to reject both tonal and broadband random vibratory disturbances is then demonstrated.

  11. Randomized Control Trials on the Dynamic Geometry Approach

    ERIC Educational Resources Information Center

    Jiang, Zhonghong; White, Alexander; Rosenwasser, Alana

    2011-01-01

    The project reported here is conducting repeated randomized control trials of an approach to high school geometry that utilizes Dynamic Geometry (DG) software to supplement ordinary instructional practices. It compares effects of that intervention with standard instruction that does not make use of computer drawing/exploration tools. The basic…

  12. Experimental results using active control of traveling wave power flow

    NASA Technical Reports Server (NTRS)

    Miller, David W.; Hall, Steven R.

    1991-01-01

    Active structural control experiments conducted on a 24-ft pinned-free beam derived feedback compensators on the basis of a traveling-wave approach. A compensator is thus obtained which eliminates resonant behavior by absorbing all impinging power. A causal solution is derived for this noncausal compensator which mimics its behavior in a given frequency range, using the Wiener-Hopf. This optimal Wiener-Hopf compensator's structure-damping performance is found to exceed any obtainable by means of rate feedback. Performance limitations encompassed the discovery of frequencies above which the sensor and actuator were no longer dual and an inadvertent coupling of the control hardware to unmodeled structure torsion modes.

  13. Social power and approach-related neural activity.

    PubMed

    Boksem, Maarten A S; Smolders, Ruud; De Cremer, David

    2012-06-01

    It has been argued that power activates a general tendency to approach whereas powerlessness activates a tendency to inhibit. The assumption is that elevated power involves reward-rich environments, freedom and, as a consequence, triggers an approach-related motivational orientation and attention to rewards. In contrast, reduced power is associated with increased threat, punishment and social constraint and thereby activates inhibition-related motivation. Moreover, approach motivation has been found to be associated with increased relative left-sided frontal brain activity, while withdrawal motivation has been associated with increased right sided activations. We measured EEG activity while subjects engaged in a task priming either high or low social power. Results show that high social power is indeed associated with greater left-frontal brain activity compared to low social power, providing the first neural evidence for the theory that high power is associated with approach-related motivation. We propose a framework accounting for differences in both approach motivation and goal-directed behaviour associated with different levels of power.

  14. Vector disparity sensor with vergence control for active vision systems.

    PubMed

    Barranco, Francisco; Diaz, Javier; Gibaldi, Agostino; Sabatini, Silvio P; Ros, Eduardo

    2012-01-01

    This paper presents an architecture for computing vector disparity for active vision systems as used on robotics applications. The control of the vergence angle of a binocular system allows us to efficiently explore dynamic environments, but requires a generalization of the disparity computation with respect to a static camera setup, where the disparity is strictly 1-D after the image rectification. The interaction between vision and motor control allows us to develop an active sensor that achieves high accuracy of the disparity computation around the fixation point, and fast reaction time for the vergence control. In this contribution, we address the development of a real-time architecture for vector disparity computation using an FPGA device. We implement the disparity unit and the control module for vergence, version, and tilt to determine the fixation point. In addition, two on-chip different alternatives for the vector disparity engines are discussed based on the luminance (gradient-based) and phase information of the binocular images. The multiscale versions of these engines are able to estimate the vector disparity up to 32 fps on VGA resolution images with very good accuracy as shown using benchmark sequences with known ground-truth. The performances in terms of frame-rate, resource utilization, and accuracy of the presented approaches are discussed. On the basis of these results, our study indicates that the gradient-based approach leads to the best trade-off choice for the integration with the active vision system.

  15. New geographical approaches to control of some parasitic zoonoses.

    PubMed Central

    Mott, K. E.; Nuttall, I.; Desjeux, P.; Cattand, P.

    1995-01-01

    The advent of new technology for geographical representation and spatial analysis of databases from different sectors offers a new approach to planning and managing the control of tropical diseases. This article reviews the geographical and intersectoral aspects of the epidemiology and control of African trypanosomiasis, cutaneous and visceral leishmaniasis, Chagas disease, schistosomiasis, and foodborne trematode infections. The focal nature of their transmission, increasing recognition of the importance of animal reservoirs, and the need to understand environmental factors influencing their distribution are common to all these diseases. Geographical information systems (GIS) open a completely new perspective for intersectoral collaboration in adapting new technology to promote control of these diseases. PMID:7743598

  16. UML activity diagrams in requirements specification of logic controllers

    NASA Astrophysics Data System (ADS)

    Grobelna, Iwona; Grobelny, Michał

    2015-12-01

    Logic controller specification can be prepared using various techniques. One of them is the wide understandable and user-friendly UML language and its activity diagrams. Using formal methods during the design phase increases the assurance that implemented system meets the project requirements. In the approach we use the model checking technique to formally verify a specification against user-defined behavioral requirements. The properties are usually defined as temporal logic formulas. In the paper we propose to use UML activity diagrams in requirements definition and then to formalize them as temporal logic formulas. As a result, UML activity diagrams can be used both for logic controller specification and for requirements definition, what simplifies the specification and verification process.

  17. Space Network Control Conference on Resource Allocation Concepts and Approaches

    NASA Technical Reports Server (NTRS)

    Moe, Karen L. (Editor)

    1991-01-01

    The results are presented of the Space Network Control (SNC) Conference. In the late 1990s, when the Advanced Tracking and Data Relay Satellite System is operational, Space Network communication services will be supported and controlled by the SNC. The goals of the conference were to survey existing resource allocation concepts and approaches, to identify solutions applicable to the Space Network, and to identify avenues of study in support of the SNC development. The conference was divided into three sessions: (1) Concepts for Space Network Allocation; (2) SNC and User Payload Operations Control Center (POCC) Human-Computer Interface Concepts; and (3) Resource Allocation Tools, Technology, and Algorithms. Key recommendations addressed approaches to achieving higher levels of automation in the scheduling process.

  18. An optimal control approach to probabilistic Boolean networks

    NASA Astrophysics Data System (ADS)

    Liu, Qiuli

    2012-12-01

    External control of some genes in a genetic regulatory network is useful for avoiding undesirable states associated with some diseases. For this purpose, a number of stochastic optimal control approaches have been proposed. Probabilistic Boolean networks (PBNs) as powerful tools for modeling gene regulatory systems have attracted considerable attention in systems biology. In this paper, we deal with a problem of optimal intervention in a PBN with the help of the theory of discrete time Markov decision process. Specifically, we first formulate a control model for a PBN as a first passage model for discrete time Markov decision processes and then find, using a value iteration algorithm, optimal effective treatments with the minimal expected first passage time over the space of all possible treatments. In order to demonstrate the feasibility of our approach, an example is also displayed.

  19. A new mobile robot control approach via fusion of control signals.

    PubMed

    Freire, Eduardo; Bastos-Filho, Teodiano; Sarcinelli-Filho, Mário; Carelli, Ricardo

    2004-02-01

    This paper proposes an alternative approach to address the problem of coordinating behaviors in mobile robot navigation: fusion of control signals. Such approach is based on a set of two decentralized information filters, which accomplish the data fusion involved. Besides these two fusion engines, control architectures designed according to this approach also embed a set of different controllers that generate reference signals for the robot linear and angular speeds. Such signals are delivered to the two decentralized information filters, which estimate suitable overall reference signals for the robot linear and angular speeds, respectively. Thus, the background for designing such control architectures is provided by the nonlinear systems theory, which makes this approach different from any other yet proposed. This background also allows checking control architectures designed according to the proposed approach for stability. Such analysis is carried out in the paper, and shows that the robot always reaches its final destination, in spite of either obstacles along its path or the environment layout. As an example, a control architecture is designed to guide a mobile robot in an experiment, whose results allows checking the good performance of the control architecture and validating the design approach proposed as well.

  20. Clickers in the Classroom: An Active Learning Approach

    ERIC Educational Resources Information Center

    Martyn, Margie

    2007-01-01

    Current research describes the benefits of active learning approaches. Clickers, or student response systems, are a technology used to promoted active learning. Most research on the benefits of using clickers in the classroom has shown that students become engaged and enjoy using them. However, research on learning outcomes has only compared the…

  1. Re"modeling" College Algebra: An Active Learning Approach

    ERIC Educational Resources Information Center

    Pinzon, D.; Pinzon, K.; Stackpole, M.

    2016-01-01

    In this paper, we discuss active learning in College Algebra at Georgia Gwinnett College. This approach has been used in more than 20 sections of College Algebra taught by the authors in the past four semesters. Students work in small, structured groups on guided inquiry activities after watching 15-20 minutes of videos before class. We discuss a…

  2. Activity Approach to Just Beyond the Classroom. Environmental Education Series.

    ERIC Educational Resources Information Center

    Skliar, Norman; La Mantia, Laura

    To provide teachers with some of the many activities that can be carried on "just beyond the classroom," the booklet presents plans for more than 40 outdoor education activities, all emphasizing multidisciplinary, inquiry approach to learning. The school grounds offer optimum conditions for initiating studies in the out-of-doors. While every…

  3. Parametric Robust Control and System Identification: Unified Approach

    NASA Technical Reports Server (NTRS)

    Keel, L. H.

    1996-01-01

    During the period of this support, a new control system design and analysis method has been studied. This approach deals with control systems containing uncertainties that are represented in terms of its transfer function parameters. Such a representation of the control system is common and many physical parameter variations fall into this type of uncertainty. Techniques developed here are capable of providing nonconservative analysis of such control systems with parameter variations. We have also developed techniques to deal with control systems when their state space representations are given rather than transfer functions. In this case, the plant parameters will appear as entries of state space matrices. Finally, a system modeling technique to construct such systems from the raw input - output frequency domain data has been developed.

  4. Lightweight active controlled primary mirror technology demonstrator

    NASA Astrophysics Data System (ADS)

    Mazzinghi, P.; Bratina, V.; Ferruzzi, D.; Gambicorti, L.; Simonetti, F.; Zuccaro Marchi, A.; Salinari, P.; Lisi, F.; Olivier, M.; Bursi, A.; Gallieni, D.; Biasi, R.; Pereira, J.

    2007-10-01

    This paper describes the design, manufacturing and test of a ground demonstrator of an innovative technology able to realize lightweight active controlled space-borne telescope mirror. This analysis is particularly devoted to applications for a large aperture space telescope for advanced LIDAR, but it can be used for any lightweight mirror. For a space-borne telescope the mirror weight is a fundamental parameter to be minimized (less than 15 Kg/m2), while maximizing the optical performances (optical quality better than λ/3). In order to guarantee these results, the best selected solution is a thin glass primary mirror coupled to a stiff CFRP (Carbon Fiber Reinforced Plastic) panel with a surface active control system. A preliminary design of this lightweight structure highlighted the critical areas that were deeply analyzed by the ground demonstrator: the 1 mm thick mirror survivability on launch and the actuator functional performances with low power consumption. To preserve the mirror glass the Electrostatic Locking technique was developed and is here described. The active optics technique, already widely used for ground based telescopes, consists of a metrology system (wave front sensor, WFS), a control algorithm and a system of actuators to slightly deform the primary mirror and/or displace the secondary, in a closed-loop control system that applies the computed corrections to the mirror's optical errors via actuators. These actuators types are properly designed and tested in order to guarantee satisfactory performances in terms of stroke, force and power consumption. The realized and tested ground demonstrator is a square CFRP structure with a flat mirror on the upper face and an active actuator beneath it. The test campaign demonstrated the technology feasibility and robustness, supporting the next step toward the large and flat surface with several actuators.

  5. Advanced Active Thermal Control Systems Architecture Study

    NASA Technical Reports Server (NTRS)

    Hanford, Anthony J.; Ewert, Michael K.

    1996-01-01

    The Johnson Space Center (JSC) initiated a dynamic study to determine possible improvements available through advanced technologies (not used on previous or current human vehicles), identify promising development initiatives for advanced active thermal control systems (ATCS's), and help prioritize funding and personnel distribution among many research projects by providing a common basis to compare several diverse technologies. Some technologies included were two-phase thermal control systems, light-weight radiators, phase-change thermal storage, rotary fluid coupler, and heat pumps. JSC designed the study to estimate potential benefits from these various proposed and under-development thermal control technologies for five possible human missions early in the next century. The study compared all the technologies to a baseline mission using mass as a basis. Each baseline mission assumed an internal thermal control system; an external thermal control system; and aluminum, flow-through radiators. Solar vapor compression heat pumps and light-weight radiators showed the greatest promise as general advanced thermal technologies which can be applied across a range of missions. This initial study identified several other promising ATCS technologies which offer mass savings and other savings compared to traditional thermal control systems. Because the study format compares various architectures with a commonly defined baseline, it is versatile and expandable, and is expected to be updated as needed.

  6. Active Thermal Control System Development for Exploration

    NASA Technical Reports Server (NTRS)

    Westheimer, David

    2007-01-01

    All space vehicles or habitats require thermal management to maintain a safe and operational environment for both crew and hardware. Active Thermal Control Systems (ATCS) perform the functions of acquiring heat from both crew and hardware within a vehicle, transporting that heat throughout the vehicle, and finally rejecting that energy into space. Almost all of the energy used in a space vehicle eventually turns into heat, which must be rejected in order to maintain an energy balance and temperature control of the vehicle. For crewed vehicles, Active Thermal Control Systems are pumped fluid loops that are made up of components designed to perform these functions. NASA has been actively developing technologies that will enable future missions or will provide significant improvements over the state of the art technologies. These technologies have are targeted for application on the Crew Exploration Vehicle (CEV), or Orion, and a Lunar Surface Access Module (LSAM). The technologies that have been selected and are currently under development include: fluids that enable single loop ATCS architectures, a gravity insensitive vapor compression cycle heat pump, a sublimator with reduced sensitivity to feedwater contamination, an evaporative heat sink that can operate in multiple ambient pressure environments, a compact spray evaporator, and lightweight radiators that take advantage of carbon composites and advanced optical coatings.

  7. Active control of electric potential of spacecraft

    NASA Technical Reports Server (NTRS)

    Goldstein, R.

    1977-01-01

    Techniques are discussed for controlling the potential of a spacecraft by means of devices which release appropriate charged particles from the spacecraft to the environment. Attention is given to electron emitters, ion emitters, a basic electron emitter arrangement, techniques for sensing electric field or potential, and flight experiments on active potential control. It is recommended to avoid differential charging on spacecraft surfaces because it can severely affect the efficacy of emitters. Discharging the frame of a spacecraft with dielectric surfaces involves the risk of stressing the dielectric material excessively. The spacecraft should, therefore, be provided with grounded conductive surfaces. It is pointed out that particles released by control systems can return to the spacecraft.

  8. The Middeck Active Control Experiment (MACE)

    NASA Technical Reports Server (NTRS)

    Miller, David W.; Sepe, Raymond B.; Rey, Daniel; Saarmaa, Erik; Crawley, Edward F.

    1993-01-01

    The Middeck Active Control Experiment (MACE) is a NASA In-Step and Control Structure Interaction (CSI) Office funded Shuttle middeck experiment. The objective is to investigate the extent to which closed-loop behavior of flexible spacecraft in zero-gravity (0-g) can be predicted. This prediction becomes particularly difficult when dynamic behavior during ground testing exhibits extensive suspension and direct gravity coupling. On-orbit system identification and control reconfiguration is investigated to improve performance which would otherwise be limited due to errors in prediction. The program is presently in its preliminary design phase with launch expected in the summer of 1994. The MACE test article consists of three attitude control torque wheels, a two axis gimballing payload, inertial sensors and a flexible support structure. With the acquisition of a second payload, this will represent a multiple payload platform with significant structural flexibility. This paper presents on-going work in the areas of modelling and control of the MACE test article in the zero and one-gravity environments. Finite element models, which include suspension and gravity effects, and measurement models, derived from experimental data, are used as the basis for Linear Quadratic Gaussian controller designs. Finite element based controllers are analytically used to study the differences in closed-loop performance as the test article transitions between the 0-g and 1-g environments. Measurement based controllers are experimentally applied to the MACE test article in the 1-g environment and achieve over an order of magnitude improvement in payload pointing accuracy when disturbed by a broadband torque disturbance. The various aspects of the flight portion of the experiment are also discussed.

  9. Energy effective approach for activation of metallurgical slag

    NASA Astrophysics Data System (ADS)

    Mazov, I. N.; Khaydarov, B. B.; Mamulat, S. L.; Suvorov, D. S.; Saltikova, Y. S.; Yudin, A. G.; Kuznetsov, D. V.

    2016-01-01

    The paper presents results of investigation of the process of mechanical activation of metallurgical slag using different approaches - ball milling and electromagnetic vortex apparatus. Particle size distribution and structure of mechanically activated slag samples were investigated, as well as energetic parameters of the activation process. It was shown that electromagnetic vortex activation is more energy effective and allows to produce microscale milled slag-based concrete using very short treatment time. Activated slag materials can be used as clinker-free cement in civilian and road construction, providing ecology-friendly technology and recycling of high-tonnage industrial waste.

  10. Active structural control design and experiment for the Mini-Mast

    NASA Technical Reports Server (NTRS)

    Wie, Bong; Horta, Lucas; Sulla, Jeff

    1990-01-01

    Control system design and closed-loop test results for the Mini-Mast truss structure located at the NASA Langley Research Center are presented. The simplicity and effectiveness of a classical control approach to the active structural control design are demonstrated by ground experiments. The concepts of robust nonminimum phase compensation and periodic disturbance rejection are also experimentally validated. The practicality of a sensor output decoupling approach is demonstrated for the inherent, multivariable control problem of the Mini-Mast.

  11. Issues and approaches in control for autonomous reactor operation

    SciTech Connect

    Vilim, R. B.; Khalil, H. S.; Wei, T. Y. C.

    2000-07-20

    A capability for autonomous and passively safe operation is one of the goals of the NERI funded development of Generation IV nuclear plants. An approach is described for evaluating the effect of increasing autonomy on safety margins and load behavior and for examining issues that arise with increasing autonomy and their potential impact on performance. The method provides a formal approach to the process of exploiting the innate self-regulating property of a reactor to make it less dependent on operator action and less vulnerable to automatic control system fault and/or operator error. Some preliminary results are given.

  12. Controlling Particle Morphologies at Fluid Interfaces: Macro- and Micro- approaches

    NASA Astrophysics Data System (ADS)

    Beesabathuni, Shilpa Naidu

    The controlled generation of varying shaped particles is important for many applications: consumer goods, biomedical diagnostics, food processing, adsorbents and pharmaceuticals which can benefit from the availability of geometrically complex and chemically inhomogeneous particles. This thesis presents two approaches to spherical and non-spherical particle synthesis using macro and microfluidics. In the first approach, a droplet microfluidic technique is explored to fabricate spherical conducting polymer, polyaniline, particles with precise control over morphology and functionality. Microfluidics has recently emerged as an important alternate to the synthesis of complex particles. The conducting polymer, polyaniline, is widely used and known for its stability, high conductivity, and favorable redox properties. In this approach, monodisperse micron-sized polyaniline spherical particles were synthesized using two-phase droplet microfluidics from Aniline and Ammonium persulfate oxidative polymerization in an oil-based continuous phase. The morphology of the polymerized particles is porous in nature which can be used for encapsulation as well as controlled release applications. Encapsulation of an enzyme, glucose oxidase, was also performed using the technique to synthesize microspheres for glucose sensing. The polymer microspheres were characterized using SEM, UV-Vis and EDX to understand the relationship between their microstructure and stability. In the second approach, molten drop impact in a cooling aqueous medium to generate non-spherical particles was explored. Viscoelastic wax based materials are widely used in many applications and their performance and application depends on the particle morphology and size. The deformation of millimeter size molten wax drops as they impacted an immiscible liquid interface was investigated. Spherical molten wax drops impinged on a cooling water bath, then deformed and as a result of solidification were arrested into various

  13. A new approach for vibration control in large space structures

    NASA Technical Reports Server (NTRS)

    Kumar, K.; Cochran, J. E., Jr.

    1987-01-01

    An approach for augmenting vibration damping characteristics in space structures with large panels is presented. It is based on generation of bending moments rather than forces. The moments are generated using bimetallic strips, suitably mounted at selected stations on both sides of the large panels, under the influence of differential solar heating, giving rise to thermal gradients and stresses. The collocated angular velocity sensors are utilized in conjunction with mini-servos to regulate the control moments by flipping the bimetallic strips. A simple computation of the rate of dissipation of vibrational energy is undertaken to assess the effectiveness of the proposed approach.

  14. Structural tailoring and feedback control synthesis - An interdisciplinary approach

    NASA Technical Reports Server (NTRS)

    Belvin, W. Keith; Park, K. C.

    1988-01-01

    Structural tailoring provides an attractive method to optimize the performance of actively controlled space structures. However, the simultaneous optimization of control gains and structural properties often becomes prohibitively expensive for large systems and physical insight is often lost in the resulting control law. This paper presents a method for optimization of the closed loop structural system using only structural tailoring. Optimal Linear Quadratic Regulator (LQR) control theory is used with weighting matrices chosen based on physical considerations. The LQR control law depends only on two scalar gains and the structural properties. Hence, the closed loop-performance can be expressed in terms of the structural parameters. Results are given for a beam and a truss-beam to show the simplicity of the method and the importance of structural tailoring to increase dynamic performance and to reduce the control effort.

  15. Geometrical approach to neural net control of movements and posture

    NASA Technical Reports Server (NTRS)

    Pellionisz, A. J.; Ramos, C. F.

    1993-01-01

    In one approach to modeling brain function, sensorimotor integration is described as geometrical mapping among coordinates of non-orthogonal frames that are intrinsic to the system; in such a case sensors represent (covariant) afferents and motor effectors represent (contravariant) motor efferents. The neuronal networks that perform such a function are viewed as general tensor transformations among different expressions and metric tensors determining the geometry of neural functional spaces. Although the non-orthogonality of a coordinate system does not impose a specific geometry on the space, this "Tensor Network Theory of brain function" allows for the possibility that the geometry is non-Euclidean. It is suggested that investigation of the non-Euclidean nature of the geometry is the key to understanding brain function and to interpreting neuronal network function. This paper outlines three contemporary applications of such a theoretical modeling approach. The first is the analysis and interpretation of multi-electrode recordings. The internal geometries of neural networks controlling external behavior of the skeletomuscle system is experimentally determinable using such multi-unit recordings. The second application of this geometrical approach to brain theory is modeling the control of posture and movement. A preliminary simulation study has been conducted with the aim of understanding the control of balance in a standing human. The model appears to unify postural control strategies that have previously been considered to be independent of each other. Third, this paper emphasizes the importance of the geometrical approach for the design and fabrication of neurocomputers that could be used in functional neuromuscular stimulation (FNS) for replacing lost motor control.

  16. Attack-tolerant networked control system: an approach for detection the controller stealthy hijacking attack

    NASA Astrophysics Data System (ADS)

    Atta Yaseen, Amer; Bayart, Mireille

    2017-01-01

    In this work, a new approach will be introduced as a development for the attack-tolerant scheme in the Networked Control System (NCS). The objective is to be able to detect an attack such as the Stuxnet case where the controller is reprogrammed and hijacked. Besides the ability to detect the stealthy controller hijacking attack, the advantage of this approach is that there is no need for a priori mathematical model of the controller. In order to implement the proposed scheme, a specific detector for the controller hijacking attack is designed. The performance of this scheme is evaluated be connected the detector to NCS with basic security elements such as Data Encryption Standard (DES), Message Digest (MD5), and timestamp. The detector is tested along with networked PI controller under stealthy hijacking attack. The test results of the proposed method show that the hijacked controller can be significantly detected and recovered.

  17. Controlling aliased dynamics in motion systems? An identification for sampled-data control approach

    NASA Astrophysics Data System (ADS)

    Oomen, Tom

    2014-07-01

    Sampled-data control systems occasionally exhibit aliased resonance phenomena within the control bandwidth. The aim of this paper is to investigate the aspect of these aliased dynamics with application to a high performance industrial nano-positioning machine. This necessitates a full sampled-data control design approach, since these aliased dynamics endanger both the at-sample performance and the intersample behaviour. The proposed framework comprises both system identification and sampled-data control. In particular, the sampled-data control objective necessitates models that encompass the intersample behaviour, i.e., ideally continuous time models. Application of the proposed approach on an industrial wafer stage system provides a thorough insight and new control design guidelines for controlling aliased dynamics.

  18. Optical control of protein function through unnatural amino acid mutagenesis and other optogenetic approaches.

    PubMed

    Baker, Austin S; Deiters, Alexander

    2014-07-18

    Biological processes are naturally regulated with high spatial and temporal resolution at the molecular, cellular, and systems level. To control and study processes with the same resolution, light-sensitive groups and domains have been employed to optically activate and deactivate protein function. Optical control is a noninvasive technique in which the amplitude, wavelength, spatial location, and timing of the light illumination can be easily controlled. This review focuses on applications of genetically encoded unnatural amino acids containing light-removable protecting groups to optically trigger protein function, while also discussing select optogenetic approaches using natural light-sensitive domains to engineer optical control of biological processes.

  19. Middeck Active Control Experiment (MACE), phase A

    NASA Technical Reports Server (NTRS)

    Crawley, Edward F.; Deluis, Javier; Miller, David W.

    1989-01-01

    A rationale to determine which structural experiments are sufficient to verify the design of structures employing Controlled Structures Technology was derived. A survey of proposed NASA missions was undertaken to identify candidate test articles for use in the Middeck Active Control Experiment (MACE). The survey revealed that potential test articles could be classified into one of three roles: development, demonstration, and qualification, depending on the maturity of the technology and the mission the structure must fulfill. A set of criteria was derived that allowed determination of which role a potential test article must fulfill. A review of the capabilities and limitations of the STS middeck was conducted. A reference design for the MACE test article was presented. Computing requirements for running typical closed-loop controllers was determined, and various computer configurations were studied. The various components required to manufacture the structure were identified. A management plan was established for the remainder of the program experiment development, flight and ground systems development, and integration to the carrier. Procedures for configuration control, fiscal control, and safety, reliabilty, and quality assurance were developed.

  20. An Integrated Approach to Damage Accommodation in Flight Control

    NASA Technical Reports Server (NTRS)

    Boskovic, Jovan D.; Knoebel, Nathan; Mehra, Raman K.; Gregory, Irene

    2008-01-01

    In this paper we present an integrated approach to in-flight damage accommodation in flight control. The approach is based on Multiple Models, Switching and Tuning (MMST), and consists of three steps: In the first step the main objective is to acquire a realistic aircraft damage model. Modeling of in-flight damage is a highly complex problem since there is a large number of issues that need to be addressed. One of the most important one is that there is strong coupling between structural dynamics, aerodynamics, and flight control. These effects cannot be studied separately due to this coupling. Once a realistic damage model is available, in the second step a large number of models corresponding to different damage cases are generated. One possibility is to generate many linear models and interpolate between them to cover a large portion of the flight envelope. Once these models have been generated, we will implement a recently developed-Model Set Reduction (MSR) technique. The technique is based on parameterizing damage in terms of uncertain parameters, and uses concepts from robust control theory to arrive at a small number of "centered" models such that the controllers corresponding to these models assure desired stability and robustness properties over a subset in the parametric space. By devising a suitable model placement strategy, the entire parametric set is covered with a relatively small number of models and controllers. The third step consists of designing a Multiple Models, Switching and Tuning (MMST) strategy for estimating the current operating regime (damage case) of the aircraft, and switching to the corresponding controller to achieve effective damage accommodation and the desired performance. In the paper present a comprehensive approach to damage accommodation using Model Set Design,MMST, and Variable Structure compensation for coupling nonlinearities. The approach was evaluated on a model of F/A-18 aircraft dynamics under control effector damage

  1. Multiscale approach to the control of smart structures

    NASA Astrophysics Data System (ADS)

    Chou, Kenneth C.; Flamm, David S.; Guthart, Gary S.; Ueberschaer, Ronald M.

    1996-05-01

    The development of control technology specifically for smart structures and materials has lagged substantially behind that of the base materials, transducers, and embedding techniques. Still, development of smart structures with ever-greater numbers of embedded elements continues, spurred by potential uses that require large arrays of sensors and actuators. For example, rather than implementing a control design that is sensitive to the particular device layout, a densely sampled array allows the controller to optimize the use of sensor information and actuator authority. No control technology suitable for such large arrays exists, however, and this presents a barrier to future applications. In this paper we report on recent progress in developing and demonstrating technology capable of controlling hundreds or thousands of sensors and actuators embedded in the base material. We have dubbed this the `KIKO control problem' (Kilo-Input/Kilo-Output) for smart materials. This paper focuses on a new multiscale/multirate theory of hierarchical design based on the wavelet transform. In the context of this theory, we develop efficient and highly scalable implementations of control systems using multiprocessor architectures. The paper describes our multiscale control approach and presents simulation results on a flexible plate.

  2. A systematic review of current and emergent manipulator control approaches

    NASA Astrophysics Data System (ADS)

    Ajwad, Syed Ali; Iqbal, Jamshed; Ullah, Muhammad Imran; Mehmood, Adeel

    2015-06-01

    Pressing demands of productivity and accuracy in today's robotic applications have highlighted an urge to replace classical control strategies with their modern control counterparts. This recent trend is further justified by the fact that the robotic manipulators have complex nonlinear dynamic structure with uncertain parameters. Highlighting the authors' research achievements in the domain of manipulator design and control, this paper presents a systematic and comprehensive review of the state-of-the-art control techniques that find enormous potential in controlling manipulators to execute cuttingedge applications. In particular, three kinds of strategies, i.e., intelligent proportional-integral-derivative (PID) scheme, robust control and adaptation based approaches, are reviewed. Future trend in the subject area is commented. Open-source simulators to facilitate controller design are also tabulated. With a comprehensive list of references, it is anticipated that the review will act as a firsthand reference for researchers, engineers and industrialinterns to realize the control laws for multi-degree of freedom (DOF) manipulators.

  3. 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.

  4. A neural-network approach to robotic control

    NASA Technical Reports Server (NTRS)

    Graham, D. P. W.; Deleuterio, G. M. T.

    1993-01-01

    An artificial neural-network paradigm for the control of robotic systems is presented. The approach is based on the Cerebellar Model Articulation Controller created by James Albus and incorporates several extensions. First, recognizing the essential structure of multibody equations of motion, two parallel modules are used that directly reflect the dynamical characteristics of multibody systems. Second, the architecture of the proposed network is imbued with a self-organizational capability which improves efficiency and accuracy. Also, the networks can be arranged in hierarchical fashion with each subsequent network providing finer and finer resolution.

  5. Optimal control of underactuated mechanical systems: A geometric approach

    NASA Astrophysics Data System (ADS)

    Colombo, Leonardo; Martín De Diego, David; Zuccalli, Marcela

    2010-08-01

    In this paper, we consider a geometric formalism for optimal control of underactuated mechanical systems. Our techniques are an adaptation of the classical Skinner and Rusk approach for the case of Lagrangian dynamics with higher-order constraints. We study a regular case where it is possible to establish a symplectic framework and, as a consequence, to obtain a unique vector field determining the dynamics of the optimal control problem. These developments will allow us to develop a new class of geometric integrators based on discrete variational calculus.

  6. Parametric robust control and system identification: Unified approach

    NASA Technical Reports Server (NTRS)

    Keel, Leehyun

    1994-01-01

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

  7. Learning motor control in the upright position: a mechanical engineering approach.

    PubMed

    Major, R E; Johnson, G R; Butler, P B

    2001-01-01

    Motor control problems that result from damage to the central nervous system can make it difficult to learn functional activities. Although several therapeutic approaches attempt to address such problems there is little evidence of their efficacy. Targeted Training is a new approach, based on a biomechanical analysis of the problem, which usually relies on specifically designed equipment. This paper describes the underlying theory, the development of functional specifications, the translation of these specifications into an engineering design and the clinical results of applying the equipment. The promotion of head and trunk control provides an example of the process.

  8. College Student Environmental Activism: How Experiences and Identities Influence Environmental Activism Approaches

    ERIC Educational Resources Information Center

    King, Laura A. H.

    2016-01-01

    College student environmental activism is one way students civically engage in addressing social issues. This study explores the environmental activism of twelve college students and how their experiences outside of college and in college influenced their activism. In addition, how students' identities influenced their approach to activism was…

  9. Active and passive control of zinc phthalocyanine photodynamics.

    PubMed

    Sharma, Divya; Huijser, Annemarie; Savolainen, Janne; Steen, Gerwin; Herek, Jennifer L

    2013-01-01

    In this work we report on the ultrafast photodynamics of the photosensitizer zinc phthalocyanine (ZnPc) and manipulation thereof. Two approaches are followed: active control via pulse shaping and passive control via strategic manipulation in the periphery of the molecular structure. The objective of both of these control experiments is the same: to enhance the yield of the functional pathway and to minimize loss channels. The aim of the active control experiments is to increase the intersystem crossing yield in ZnPc, which is important for application in photodynamic therapy (PDT). Pulse shaping allowed an improvement in triplet to singlet ratio of 15% as compared to a transform-limited pulse. This effect is ascribed to a control mechanism that utilizes multiphoton pathways to higher-lying states from where intersystem crossing is more likely to occur. The passive control experiments are performed on ZnPc derivatives deposited onto TiO2, serving as a model system of a dye-sensitized solar cell (DSSC). Modification of the anchoring ligand of the molecular structure resulted in an increased rate for electron injection into TiO2 and slower back electron transfer, improving the DSSC efficiency.

  10. A practical approach for minimum time control of the Spacecraft Control Laboratory Experiment (SCOLE), appendix A

    NASA Technical Reports Server (NTRS)

    Kaufman, H.; Kyriakopoulos, K. J.

    1989-01-01

    The Space COntrol Laboratory Experiment (SCOLE) is a challenge for control engineering applications. This is a result of the system dynamics, the available measurement information, the actuator capabilities and finally the specified performance requirements set. Results on the use of Model Reference Adaptive Control were reported. In view of the necessity for rapid response, this work deals with an optimal control formulation, with a minimum time requirement and constrained input. A mathematical statement of the problem is presented. The time optimal control formulation is presented and the reasons that make such an approach not promising are discussed. As a result, a pseudo time-optimal control algorithm is discussed. The proposed approach is tested to see if it satisfies the design specifications, and finally a discussion and suggestions for further research are provided.

  11. Supramolecular Approaches to Nanoscale Morphological Control in Organic Solar Cells.

    PubMed

    Haruk, Alexander M; Mativetsky, Jeffrey M

    2015-06-11

    Having recently surpassed 10% efficiency, solar cells based on organic molecules are poised to become a viable low-cost clean energy source with the added advantages of mechanical flexibility and light weight. The best-performing organic solar cells rely on a nanostructured active layer morphology consisting of a complex organization of electron donating and electron accepting molecules. Although much progress has been made in designing new donor and acceptor molecules, rational control over active layer morphology remains a central challenge. Long-term device stability is another important consideration that needs to be addressed. This review highlights supramolecular strategies for generating highly stable nanostructured organic photovoltaic active materials by design.

  12. Control concepts for active magnetic bearings

    NASA Technical Reports Server (NTRS)

    Siegwart, Roland; Vischer, D.; Larsonneur, R.; Herzog, R.; Traxler, Alfons; Bleuler, H.; Schweitzer, G.

    1992-01-01

    Active Magnetic Bearings (AMB) are becoming increasingly significant for various industrial applications. Examples are turbo-compressors, centrifuges, high speed milling and grinding spindles, vibration isolation, linear guides, magnetically levitated trains, vacuum and space applications. Thanks to the rapid progress and drastic cost reduction in power- and micro-electronics, the number of AMB applications is growing very rapidly. Industrial uses of AMBs leads to new requirements for AMB-actuators, sensor systems, and rotor dynamics. Especially desirable are new and better control concepts to meet demand such as low cost AMB, high stiffness, high performance, high robustness, high damping up to several kHz, vibration isolation, force-free rotation, and unbalance cancellation. This paper surveys various control concepts for AMBs and discusses their advantages and disadvantages. Theoretical and experimental results are presented.

  13. Active Displacement Control of Active Magnetic Bearing System

    NASA Astrophysics Data System (ADS)

    Kertész, Milan; Kozakovič, Radko; Magdolen, Luboš; Masaryk, Michal

    2014-12-01

    The worldwide energy production nowadays is over 3400 GW while storage systems have a capacity of only 90 GW [1]. There is a good solution for additional storage capacity in flywheel energy storage systems (FES). The main advantage of FES is its relatively high efficiency especially with using the active magnetic bearing system. Therefore there exist good reasons for appropriate simulations and for creating a suitable magneto-structural control system. The magnetic bearing, including actuation, is simulated in the ANSYS parametric design language (APDL). APDL is used to create the loops of transient simulations where boundary conditions (BC) are updated based upon a "gap sensor" which controls the nodal position values of the centroid of the shaft and the current density inputs onto the copper windings.

  14. A New Approach to Attitude Stability and Control for Low Airspeed Vehicles

    NASA Technical Reports Server (NTRS)

    Lim, K. B.; Shin, Y-Y.; Moerder, D. D.; Cooper, E. G.

    2004-01-01

    This paper describes an approach for controlling the attitude of statically unstable thrust-levitated vehicles in hover or slow translation. The large thrust vector that characterizes such vehicles can be modulated to provide control forces and moments to the airframe, but such modulation is accompanied by significant unsteady flow effects. These effects are difficult to model, and can compromise the practical value of thrust vectoring in closed-loop attitude stability, even if the thrust vectoring machinery has sufficient bandwidth for stabilization. The stabilization approach described in this paper is based on using internal angular momentum transfer devices for stability, augmented by thrust vectoring for trim and other "outer loop" control functions. The three main components of this approach are: (1) a z-body axis angular momentum bias enhances static attitude stability, reducing the amount of control activity needed for stabilization, (2) optionally, gimbaled reaction wheels provide high-bandwidth control torques for additional stabilization, or agility, and (3) the resulting strongly coupled system dynamics are controlled by a multivariable controller. A flight test vehicle is described, and nonlinear simulation results are provided that demonstrate the efficiency of the approach.

  15. Active Aircraft Pylon Noise Control System

    NASA Technical Reports Server (NTRS)

    Thomas, Russell H. (Inventor); Czech, Michael J (Inventor); Elmiligui, Alaa A. (Inventor)

    2015-01-01

    An active pylon noise control system for an aircraft includes a pylon structure connecting an engine system with an airframe surface of the aircraft and having at least one aperture to supply a gas or fluid therethrough, an intake portion attached to the pylon structure to intake a gas or fluid, a regulator connected with the intake portion via a plurality of pipes, to regulate a pressure of the gas or fluid, a plenum chamber formed within the pylon structure and connected with the regulator, and configured to receive the gas or fluid as regulated by the regulator, and a plurality of injectors in communication with the plenum chamber to actively inject the gas or fluid through the plurality of apertures of the pylon structure.

  16. Active noise control for infant incubators.

    PubMed

    Yu, Xun; Gujjula, Shruthi; Kuo, Sen M

    2009-01-01

    This paper presents an active noise control system for infant incubators. Experimental results show that global noise reduction can be achieved for infant incubator ANC systems. An audio-integration algorithm is presented to introduce a healthy audio (intrauterine) sound with the ANC system to mask the residual noise and soothe the infant. Carbon nanotube based transparent thin film speaker is also introduced in this paper as the actuator for the ANC system to generate the destructive secondary sound, which can significantly save the congested incubator space and without blocking the view of doctors and nurses.

  17. Access Control for Agent-based Computing: A Distributed Approach.

    ERIC Educational Resources Information Center

    Antonopoulos, Nick; Koukoumpetsos, Kyriakos; Shafarenko, Alex

    2001-01-01

    Discusses the mobile software agent paradigm that provides a foundation for the development of high performance distributed applications and presents a simple, distributed access control architecture based on the concept of distributed, active authorization entities (lock cells), any combination of which can be referenced by an agent to provide…

  18. Hybrid Architecture Active Wavefront Sensing and Control

    NASA Technical Reports Server (NTRS)

    Feinberg, Lee; Dean, Bruce; Hyde, Tupper

    2010-01-01

    A method was developed for performing relatively high-speed wavefront sensing and control to overcome thermal instabilities in a segmented primary mirror telescope [e.g., James Webb Space Telescope (JWST) at L2], by using the onboard fine guidance sensor (FGS) to minimize expense and complexity. This FGS performs centroiding on a bright star to feed the information to the pointing and control system. The proposed concept is to beam split the image of the guide star (or use a single defocused guide star image) to perform wavefront sensing using phase retrieval techniques. Using the fine guidance sensor star image for guiding and fine phasing eliminates the need for other, more complex ways of achieving very accurate sensing and control that is needed for UV-optical applications. The phase retrieval occurs nearly constantly, so passive thermal stability over fourteen days is not required. Using the FGS as the sensor, one can feed segment update information to actuators on the primary mirror that can update the primary mirror segment fine phasing with this frequency. Because the thermal time constants of the primary mirror are very slow compared to this duration, the mirror will appear extremely stable during observations (to the level of accuracy of the sensing and control). The sensing can use the same phase retrieval techniques as the JWST by employing an additional beam splitter, and having each channel go through a weak lens (one positive and one negative). The channels can use common or separate detectors. Phase retrieval can be performed onboard. The actuation scheme would include a coarse stage able to achieve initial alignment of several millimeters of range (similar to JWST and can use a JWST heritage sensing approach in the science camera) and a fine stage capable of continual updates.

  19. A Social Identity Approach to Understanding and Promoting Physical Activity.

    PubMed

    Stevens, Mark; Rees, Tim; Coffee, Pete; Steffens, Niklas K; Haslam, S Alexander; Polman, Remco

    2017-03-27

    Against the backdrop of a global physical inactivity crisis, attempts to both understand and positively influence physical activity behaviours are characterized by a focus on individual-level factors (e.g. cognitions, attitudes, motivation). We outline a new perspective, drawn from an emerging body of work exploring the applicability of social identity and self-categorization theories to domains of sport and health, from which to understand and address this pervasive problem. This social identity approach suggests that the groups to which people belong can be, and often are, incorporated into their sense of self and, through this, are powerful determinants of physical activity-related behaviour. We start by reviewing the current state of physical activity research and highlighting the potential for the social identity approach to help understand how social factors influence these behaviours. Next, we outline the theoretical underpinnings of the social identity approach and provide three key examples that speak to the analytical and practical value of the social identity approach in physical activity settings. Specifically, we argue that social identity (1) can be harnessed to promote engagement in physical activity, (2) underpins exercise group behaviour, and (3) underpins effective leadership in exercise settings. We conclude by identifying prospects for a range of theory-informed research developments.

  20. Active control system for high speed windmills

    DOEpatents

    Avery, Don E.

    1988-01-01

    A pump stroke is matched to the operating speed of a high speed windmill. The windmill drives a hydraulic pump for a control. Changes in speed of a wind driven shaft open supply and exhaust valves to opposite ends of a hydraulic actuator to lengthen and shorten an oscillating arm thereby lengthening and shortening the stroke of an output pump. Diminishing wind to a stall speed causes the valves to operate the hydraulic cylinder to shorten the oscillating arm to zero. A pressure accumulator in the hydraulic system provides the force necessary to supply the hydraulic fluid under pressure to drive the actuator into and out of the zero position in response to the windmill shaft speed approaching and exceeding windmill stall speed.

  1. Active control system for high speed windmills

    DOEpatents

    Avery, D.E.

    1988-01-12

    A pump stroke is matched to the operating speed of a high speed windmill. The windmill drives a hydraulic pump for a control. Changes in speed of a wind driven shaft open supply and exhaust valves to opposite ends of a hydraulic actuator to lengthen and shorten an oscillating arm thereby lengthening and shortening the stroke of an output pump. Diminishing wind to a stall speed causes the valves to operate the hydraulic cylinder to shorten the oscillating arm to zero. A pressure accumulator in the hydraulic system provides the force necessary to supply the hydraulic fluid under pressure to drive the actuator into and out of the zero position in response to the windmill shaft speed approaching and exceeding windmill stall speed. 4 figs.

  2. Control of Dual-Opposed Stirling Convertors with Active Power Factor Correction Controllers

    NASA Technical Reports Server (NTRS)

    Regan, Timothy F.; Lewandowski, Edward J.; Schreiber, Jeffrey G.

    2006-01-01

    When using recently-developed active power factor correction (APFC) controllers in power systems comprised of dual-opposed free-piston Stirling convertors, a variety of configurations of the convertors and controller(s) can be considered, with configuration ultimately selected based on benefits of efficiency, reliability, and robust operation. The configuration must not only achieve stable control of the two convertors, but also synchronize and regulate motion of the pistons to minimize net dynamic forces. The NASA Glenn Research Center (GRC) System Dynamic Model (SDM) was used to study ten configurations of dual-opposed convertor systems. These configurations considered one controller with the alternators connected in series or in parallel, and two controllers with the alternators not connected (isolated). For the configurations where the alternators were not connected, several different approaches were evaluated to synchronize the two convertors. In addition, two thermodynamic configurations were considered: two convertors with isolated working spaces and convertors with a shared expansion space. Of the ten configurations studied, stable operating modes were found for four. Three of those four had a common expansion space. One stable configuration was found for the dual-opposed convertors with separate working spaces. That configuration required isochronous control of both convertors, and two APFC controllers were used to accomplish this. A frequency/phase control loop was necessary to allow each APFC controller to synchronize its associated convertor with a common frequency.

  3. Control of Dual-Opposed Stirling Convertors with Active Power Factor Correction Controllers

    NASA Technical Reports Server (NTRS)

    Regan, Timothy F.; Lewandowski, Edward J.; Schreiber, Jeffrey G.

    2007-01-01

    When using recently-developed active power factor correction (APFC) controllers in power systems comprised of dual-opposed free-piston Stirling convertors, a variety of configurations of the convertors and controller(s) can be considered, with configuration ultimately selected based on benefits of efficiency, reliability, and robust operation. The configuration must not only achieve stable control of the two convertors, but also synchronize and regulate motion of the pistons to minimize net dynamic forces. The NASA Glenn Research Center (GRC) System Dynamic Model (SDM) was used to study ten configurations of dual-opposed convertor systems. These configurations considered one controller with the alternators connected in series or in parallel, and two controllers with the alternators not connected (isolated). For the configurations where the alternators were not connected, several different approaches were evaluated to synchronize the two convertors. In addition, two thermodynamic configurations were considered: two convertors with isolated working spaces and convertors with a shared expansion space. Of the ten configurations studied, stable operating modes were found for four. Three of those four had a common expansion space. One stable configuration was found for the dual-opposed convertors with separate working spaces. That configuration required isochronous control of both convertors, and two APFC controllers were used to accomplish this. A frequency/phase control loop was necessary to allow each APFC controller to synchronize its associated convertor with a common frequency.

  4. Control of Bovine Mastitis: Old and Recent Therapeutic Approaches.

    PubMed

    Gomes, Fernanda; Henriques, Mariana

    2016-04-01

    Mastitis is defined as the inflammatory response resulting of the infection of the udder tissue and it is reported in numerous species, namely in domestic dairy animals. This pathology is the most frequent disease of dairy cattle and can be potentially fatal. Mastitis is an economically important pathology associated with reduced milk production, changes in milk composition and quality, being considered one of the most costly to dairy industry. Therefore, the majority of research in the field has focused on control of bovine mastitis and many efforts are being made for the development of new and effective anti-mastitis drugs. Antibiotic treatment is an established component of mastitis control programs; however, the continuous search for new therapeutic alternatives, effective in the control and treatment of bovine mastitis, is urgent. This review will provide an overview of some conventional and emerging approaches in the management of bovine mastitis' infections.

  5. Stall Recovery Guidance Algorithms Based on Constrained Control Approaches

    NASA Technical Reports Server (NTRS)

    Stepanyan, Vahram; Krishnakumar, Kalmanje; Kaneshige, John; Acosta, Diana

    2016-01-01

    Aircraft loss-of-control, in particular approach to stall or fully developed stall, is a major factor contributing to aircraft safety risks, which emphasizes the need to develop algorithms that are capable of assisting the pilots to identify the problem and providing guidance to recover the aircraft. In this paper we present several stall recovery guidance algorithms, which are implemented in the background without interfering with flight control system and altering the pilot's actions. They are using input and state constrained control methods to generate guidance signals, which are provided to the pilot in the form of visual cues. It is the pilot's decision to follow these signals. The algorithms are validated in the pilot-in-the loop medium fidelity simulation experiment.

  6. Multiscale approach to the control of smart materials

    NASA Astrophysics Data System (ADS)

    Chou, Kenneth C.; Guthart, Gary S.; Flamm, David S.

    1995-05-01

    The development of control technology specifically for smart materials has lagged substantially behind that of the base materials, transducers and embedding techniques. Still, development of materials with ever- greater numbers of embedded elements continues, spurred by potential uses that require large arrays of sensors and actuators. No control technology suitable for such large arrays exists, however, and this presents a barrier to future applications. In this paper we report on work aimed at developing and demonstrating technology capable of controlling hundreds or thousands of sensors and actuators embedded in the base material. We have dubbed this the 'KIKO control problem' (Kilo- Input/Kilo-Output) for smart materials. This paper focuses on a new multiscale/multirate theory of hierarchical design based on the wavelet transform. In the context of this theory, we develop efficient and highly scalable implementations of control systems using multiprocessor architectures. The paper covers: a description of our multiscale control approach, simulation results on an Euler-Bernoulli beam, and open issues.

  7. Corrosion control under a multi-agent approach

    SciTech Connect

    Ramos, M.P.; Paraiso, E.C.; Correa, L.A.D.

    1996-10-01

    The last years have shown the great importance of monitoring techniques applied to corrosion control in process industries. These techniques depend strongly on systems for data acquisition, data treatment/analysis and automatic control. This monitoring task can be improved by the application of modern computer based solutions as intelligent systems. This paper presents the foundation of Distributed Artificial Intelligence and Multi-Agent Systems applied to corrosion control as well as presents the researches and developments of a community of expert systems (agents) for corrosion control in a crude unit environment of a petroleum refinery. The main difference between this approach and the control based on only one expert system is that in a multi-agent system several expert systems are developed each one to take care of a small part of the process. It allows the user to develop a better control of these process parts. The use of multi-agent systems also allow some independence of proprietary communication protocols.

  8. Snapshot of Active Flow Control Research at NASA Langley

    NASA Technical Reports Server (NTRS)

    Washburn, A. E.; Gorton, S. Althoff; Anders, S. G.

    2002-01-01

    NASA Langley is aggressively investigating the potential advantages of active flow control as opposed to more traditional aerodynamic techniques. Many of these techniques will be blended with advanced materials and structures to further enhance payoff. Therefore a multi-disciplinary approach to technology development is being attempted that includes researchers from the more historical disciplines of fluid mechanics. acoustics, material science, structural mechanics, and control theory. The overall goals of the topics presented are focused on advancing the state of knowledge and understanding of controllable fundamental mechanisms in fluids rather than on specific engineering problems. An organizational view of current research activities at NASA Langley in active flow control as supported by several programs such as the Morphing Project under Breakthrough Vehicle Technologies Program (BVT). the Ultra-Efficient Engine Technology Program (UEET), and the 21st Century Aircraft Technology Program (TCAT) is presented. On-center research as well as NASA Langley funded contracts and grants are discussed at a relatively high level. The products of this research, as part of the fundamental NASA R and D (research and development) program. will be demonstrated as either bench-top experiments, wind-tunnel investigations, or in flight tests. Later they will be transferred to more applied research programs within NASA, DOD (Department of Defense), and U.S. industry.

  9. Quadratic Optimization in the Problems of Active Control of Sound

    NASA Technical Reports Server (NTRS)

    Loncaric, J.; Tsynkov, S. V.; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    We analyze the problem of suppressing the unwanted component of a time-harmonic acoustic field (noise) on a predetermined region of interest. The suppression is rendered by active means, i.e., by introducing the additional acoustic sources called controls that generate the appropriate anti-sound. Previously, we have obtained general solutions for active controls in both continuous and discrete formulations of the problem. We have also obtained optimal solutions that minimize the overall absolute acoustic source strength of active control sources. These optimal solutions happen to be particular layers of monopoles on the perimeter of the protected region. Mathematically, minimization of acoustic source strength is equivalent to minimization in the sense of L(sub 1). By contrast. in the current paper we formulate and study optimization problems that involve quadratic functions of merit. Specifically, we minimize the L(sub 2) norm of the control sources, and we consider both the unconstrained and constrained minimization. The unconstrained L(sub 2) minimization is certainly the easiest problem to address numerically. On the other hand, the constrained approach allows one to analyze sophisticated geometries. In a special case, we call compare our finite-difference optimal solutions to the continuous optimal solutions obtained previously using a semi-analytic technique. We also show that the optima obtained in the sense of L(sub 2) differ drastically from those obtained in the sense of L(sub 1).

  10. Controlled release of biologically active silver from nanosilver surfaces.

    PubMed

    Liu, Jingyu; Sonshine, David A; Shervani, Saira; Hurt, Robert H

    2010-11-23

    Major pathways in the antibacterial activity and eukaryotic toxicity of nanosilver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nanosilver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nanosilver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nanosilver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nanosilver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over 4 orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by preoxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and releasing inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through a bacterial inhibition zone assay carried out on selected formulations of controlled release nanosilver.

  11. Stochastic control approaches for sensor management in search and exploitation

    NASA Astrophysics Data System (ADS)

    Hitchings, Darin Chester

    Recent improvements in the capabilities of autonomous vehicles have motivated their increased use in such applications as defense, homeland security, environmental monitoring, and surveillance. To enhance performance in these applications, new algorithms are required to control teams of robots autonomously and through limited interactions with human operators. In this dissertation we develop new algorithms for control of robots performing information-seeking missions in unknown environments. These missions require robots to control their sensors in order to discover the presence of objects, keep track of the objects, and learn what these objects are, given a fixed sensing budget. Initially, we investigate control of multiple sensors, with a finite set of sensing options and finite-valued measurements, to locate and classify objects given a limited resource budget. The control problem is formulated as a Partially Observed Markov Decision Problem (POMDP), but its exact solution requires excessive computation. Under the assumption that sensor error statistics are independent and time-invariant, we develop a class of algorithms using Lagrangian Relaxation techniques to obtain optimal mixed strategies using performance bounds developed in previous research. We investigate alternative Receding Horizon (RH) controllers to convert the mixed strategies to feasible adaptive-sensing strategies and evaluate the relative performance of these controllers in simulation. The resulting controllers provide superior performance to alternative algorithms proposed in the literature and obtain solutions to large-scale POMDP problems several orders of magnitude faster than optimal Dynamic Programming (DP) approaches with comparable performance quality. We extend our results for finite action, finite measurement sensor control to scenarios with moving objects. We use Hidden Markov Models (HMMs) for the evolution of objects, according to the dynamics of a birth-death process. We develop a

  12. Internal models for interpreting neural population activity during sensorimotor control.

    PubMed

    Golub, Matthew D; Yu, Byron M; Chase, Steven M

    2015-12-08

    To successfully guide limb movements, the brain takes in sensory information about the limb, internally tracks the state of the limb, and produces appropriate motor commands. It is widely believed that this process uses an internal model, which describes our prior beliefs about how the limb responds to motor commands. Here, we leveraged a brain-machine interface (BMI) paradigm in rhesus monkeys and novel statistical analyses of neural population activity to gain insight into moment-by-moment internal model computations. We discovered that a mismatch between subjects' internal models and the actual BMI explains roughly 65% of movement errors, as well as long-standing deficiencies in BMI speed control. We then used the internal models to characterize how the neural population activity changes during BMI learning. More broadly, this work provides an approach for interpreting neural population activity in the context of how prior beliefs guide the transformation of sensory input to motor output.

  13. Droplet activation of wet particles: development of the Wet CCN approach

    NASA Astrophysics Data System (ADS)

    Nakao, S.; Suda, S. R.; Camp, M.; Petters, M. D.; Kreidenweis, S. M.

    2014-01-01

    Relationships between critical supersaturation required for activation and particle dry diameter have been the primary means for experimentally characterizing cloud condensation nuclei (CCN) activity; however, use of the dry diameter inherently limits the application to cases where the dry diameter can be used to accurately estimate solute volume. This study challenges the requirement and proposes a new experimental approach, Wet CCN, for studying CCN activity without the need for a drying step. The new approach directly measures Köhler curves under sub-saturated conditions. The experimental setup consists of a humidity-controlled differential mobility analyzer and a CCN counter; wet diameter equilibrated at known relative humidity is used to characterize CCN activity instead of the dry diameter. The experimental approach was validated against ammonium sulfate, glucose and non-spherical ammonium oxalate monohydrate. Further, the approach was applied to a mixture of non-spherical iodine oxide particles. The Wet CCN approach successfully determined the hygroscopicity of non-spherical particles by collapsing them into spherical, deliquesced droplets. We further show that the Wet CCN approach offers unique insights to the physical and chemical impacts of the aqueous phase on CCN activity; a potential application is to investigate the impact of evaporation/co-condensation of water-soluble semi-volatile species on CCN activity.

  14. Droplet activation of wet particles: development of the Wet CCN approach

    NASA Astrophysics Data System (ADS)

    Nakao, S.; Suda, S. R.; Camp, M.; Petters, M. D.; Kreidenweis, S. M.

    2014-07-01

    Relationships between critical supersaturation required for activation and particle dry diameter have been the primary means for experimentally characterizing cloud condensation nuclei (CCN) activity; however, use of the dry diameter inherently limits the application to cases where the dry diameter can be used to accurately estimate solute volume. This study challenges the requirement and proposes a new experimental approach, Wet CCN, for studying CCN activity without the need for a drying step. The new approach directly measures the subsaturated portion of the Köhler curves. The experimental setup consists of a humidity-controlled differential mobility analyzer and a CCN counter; wet diameter equilibrated at known relative humidity is used to characterize CCN activity instead of the dry diameter. The experimental approach was validated against ammonium sulfate, glucose, and nonspherical ammonium oxalate monohydrate. Further, the approach was applied to a mixture of nonspherical iodine oxide particles. The Wet CCN approach successfully determined the hygroscopicity of nonspherical particles by collapsing them into spherical, deliquesced droplets. We further show that the Wet CCN approach offers unique insights into the physical and chemical impacts of the aqueous phase on CCN activity; a potential application is to investigate the impact of evaporation/co-condensation of water-soluble semivolatile species on CCN activity.

  15. Satellite cascade attitude control via fuzzy PD controller with active force control under momentum dumping

    NASA Astrophysics Data System (ADS)

    Ismail, Z.; Varatharajoo, R.

    2016-10-01

    In this paper, fuzzy proportional-derivative (PD) controller with active force control (AFC) scheme is studied and employed in the satellite attitude control system equipped with reaction wheels. The momentum dumping is enabled via proportional integral (PI) controller as the system is impractical without momentum dumping control. The attitude controllers are developed together with their governing equations and evaluated through numerical treatment with respect to a reference satellite mission. From the results, it is evident that the three axis attitudes accuracies can be improved up to ±0.001 degree through the fuzzy PD controller with AFC scheme for the attitude control. In addition, the three-axis wheel angular momentums are well maintained during the attitude control tasks.

  16. An innovations approach to decoupling of multibody dynamics and control

    NASA Technical Reports Server (NTRS)

    Rodriguez, G.

    1989-01-01

    The problem of hinged multibody dynamics is solved using an extension of the innovations approach of linear filtering and prediction theory to the problem of mechanical system modeling and control. This approach has been used quite effectively to diagonalize the equations for filtering and prediction for linear state space systems. It has similar advantages in the study of dynamics and control of multibody systems. The innovations approach advanced here consists of expressing the equations of motion in terms of two closely related processes: (1) the innovations process e, a sequence of moments, obtained from the applied moments T by means of a spatially recursive Kalman filter that goes from the tip of the manipulator to its base; (2) a residual process, a sequence of velocities, obtained from the joint-angle velocities by means of an outward smoothing operations. The innovations e and the applied moments T are related by means of the relationships e = (I - L)T and T = (I + K)e. The operation (I - L) is a causal lower triangular matrix which is generated by a spatially recursive Kalman filter and the corresponding discrete-step Riccati equation. Hence, the innovations and the applied moments can be obtained from each other by means of a causal operation which is itself casually invertible.

  17. Experimental study on active vibration control of a gearbox system

    NASA Astrophysics Data System (ADS)

    Guan, Yuan H.; Lim, Teik C.; Steve Shepard, W.

    2005-04-01

    An active internal gearbox structure is developed and evaluated experimentally to suppress gear pair vibration due to transmission error excitation. The approach is based on an active shaft transverse vibration control concept that was theoretically analyzed in an earlier study and determined to be one of the most feasible methods. The system comprises of a piezoelectric stack actuator for applying control forces to the shaft via a rolling element-bearing, and a highly efficient, enhanced delayed-x LMS control algorithm to generate the appropriate control signals. To avoid the aliasing effects of higher frequency signals and reduce the phase delay of conventional filters, a multi-rate minimum-phase low-pass digital filter is also integrated into the controller. The experimental results yield 8-13 dB attenuation in the gearbox housing vibration levels and correspondingly 5-8 dB reduction in measured gear whine noise levels at the first and second operating gear mesh frequencies.

  18. Using an Active-Learning Approach to Teach Epigenetics

    ERIC Educational Resources Information Center

    Colon-Berlingeri, Migdalisel

    2010-01-01

    Epigenetics involves heritable changes in gene expression that do not involve alterations in the DNA sequence. I developed an active-learning approach to convey this topic to students in a college genetics course. I posted a brief summary of the topic before class to stimulate exchange in cooperative groups. During class, we discussed the…

  19. A Behavior-Based Approach for Educational Robotics Activities

    ERIC Educational Resources Information Center

    De Cristoforis, P.; Pedre, S.; Nitsche, M.; Fischer, T.; Pessacg, F.; Di Pietro, C.

    2013-01-01

    Educational robotics proposes the use of robots as a teaching resource that enables inexperienced students to approach topics in fields unrelated to robotics. In recent years, these activities have grown substantially in elementary and secondary school classrooms and also in outreach experiences to interest students in science, technology,…

  20. A Hybrid Approach to University Subject Learning Activities

    ERIC Educational Resources Information Center

    Osorio Gomez, Luz Adriana; Duart, Josep M.

    2012-01-01

    In order to get a better understanding of subject design and delivery using a hybrid approach, we have studied a hybrid learning postgraduate programme offered by the University of the Andes, Bogota, Colombia. The study analyses students' perceptions of subject design and delivery, with particular reference to learning activities and the roles of…

  1. Anthropological Approach and Activity Theory: Culture, Communities and Institutions

    ERIC Educational Resources Information Center

    Lagrange, Jean-Baptiste

    2013-01-01

    The goal of this paper is to evaluate the contribution of the anthropological approach (AA) concurrently to Activity Theory (AT) in view of overarching questions about classroom use of technology for teaching and learning mathematics. I will do it first from a philosophical point of view, presenting the main notions of AA that have been used to…

  2. Synchronization-based approach for detecting functional activation of brain

    NASA Astrophysics Data System (ADS)

    Hong, Lei; Cai, Shi-Min; Zhang, Jie; Zhuo, Zhao; Fu, Zhong-Qian; Zhou, Pei-Ling

    2012-09-01

    In this paper, we investigate a synchronization-based, data-driven clustering approach for the analysis of functional magnetic resonance imaging (fMRI) data, and specifically for detecting functional activation from fMRI data. We first define a new measure of similarity between all pairs of data points (i.e., time series of voxels) integrating both complete phase synchronization and amplitude correlation. These pairwise similarities are taken as the coupling between a set of Kuramoto oscillators, which in turn evolve according to a nearest-neighbor rule. As the network evolves, similar data points naturally synchronize with each other, and distinct clusters will emerge. The clustering behavior of the interaction network of the coupled oscillators, therefore, mirrors the clustering property of the original multiple time series. The clustered regions whose cross-correlation coefficients are much greater than other regions are considered as the functionally activated brain regions. The analysis of fMRI data in auditory and visual areas shows that the recognized brain functional activations are in complete correspondence with those from the general linear model of statistical parametric mapping, but with a significantly lower time complexity. We further compare our results with those from traditional K-means approach, and find that our new clustering approach can distinguish between different response patterns more accurately and efficiently than the K-means approach, and therefore more suitable in detecting functional activation from event-related experimental fMRI data.

  3. An active noise control algorithm for controlling multiple sinusoids.

    PubMed

    Lee, S M; Lee, H J; Yoo, C H; Youn, D H; Cha, I W

    1998-07-01

    The filtered-x LMS algorithm and its modified versions have been successfully applied in suppressing acoustic noise such as single and multiple tones and broadband random noise. This paper presents an adaptive algorithm based on the filtered-x LMS algorithm which may be applied in attenuating tonal acoustic noise. In the proposed method, the weights of the adaptive filter and estimation of the phase shift due to the acoustic path from a loudspeaker to a microphone are computed simultaneously for optimal control. The algorithm possesses advantages over other filtered-x LMS approaches in three aspects: (1) each frequency component is processed separately using an adaptive filter with two coefficients, (2) the convergence parameter for each sinusoid can be selected independently, and (3) the computational load can be reduced by eliminating the convolution process required to obtain the filtered reference signal. Simulation results for a single-input/single-output (SISO) environment demonstrate that the proposed method is robust to the changes of the acoustic path between the actuator and the microphone and outperforms the filtered-x LMS algorithm in simplicity and convergence speed.

  4. Quorum Quenching Mediated Approaches for Control of Membrane Biofouling

    PubMed Central

    Lade, Harshad; Paul, Diby; Kweon, Ji Hyang

    2014-01-01

    Membrane biofouling is widely acknowledged as the most frequent adverse event in wastewater treatment systems resulting in significant loss of treatment efficiency and economy. Different strategies including physical cleaning and use of antimicrobial chemicals or antibiotics have been tried for reducing membrane biofouling. Such traditional practices are aimed to eradicate biofilms or kill the bacteria involved, but the greater efficacy in membrane performance would be achieved by inhibiting biofouling without interfering with bacterial growth. As a result, the search for environmental friendly non-antibiotic antifouling strategies has received much greater attention among scientific community. The use of quorum quenching natural compounds and enzymes will be a potential approach for control of membrane biofouling. This approach has previously proven useful in diseases and membrane biofouling control by triggering the expression of desired phenotypes. In view of this, the present review is provided to give the updated information on quorum quenching compounds and elucidate the significance of quorum sensing inhibition in control of membrane biofouling. PMID:24910534

  5. Substrate Activity Screening (SAS) and Related Approaches in Medicinal Chemistry.

    PubMed

    Gladysz, Rafaela; Lambeir, Anne-Marie; Joossens, Jurgen; Augustyns, Koen; Van der Veken, Pieter

    2016-03-04

    Substrate activity screening (SAS) was presented a decade ago by Ellman and co-workers as a straightforward methodology for the identification of fragment-sized building blocks for enzyme inhibitors. Ever since, SAS and variations derived from it have been successfully applied to the discovery of inhibitors of various families of enzymatically active drug targets. This review covers key achievements and challenges of SAS and related methodologies, including the modified substrate activity screening (MSAS) approach. Special attention is given to the kinetic and thermodynamic aspects of these methodologies, as a thorough understanding thereof is crucial for successfully transforming the identified fragment-sized hits into potent inhibitors.

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

    PubMed

    Alipouri, Yousef; Poshtan, Javad

    2013-03-01

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

  7. Analysis of Fusion Burn Control Approaches Using METIS

    NASA Astrophysics Data System (ADS)

    Boyer, Mark; Schuster, Eugenio; Bremond, Sylvain; Nouailletas, Remy; Artaud, Jean-Francois

    2012-10-01

    Controlling the fusion power through regulation of the plasma density and temperature is one of the most fundamental problems in fusion reactors and will be critical to the success of burning plasma experiments like ITER. In this work, a volume averaged model for the evolution of the density of energy, deuterium and tritium fuel ions, alpha-particles, and impurity ions is used to synthesize nonlinear feedback controllers for stabilizing and modulating the burn condition. Adaptive control techniques are used to account for modeling uncertainty. The control approaches make use of the different possible methods for altering the fusion power, including adjusting the temperature through auxiliary heating, modulating the density or isotopic mix through fueling, and altering the impurity density through impurity injection. The different methods are simulated and compared using a simulation framework based around METIS, a module of the CRONOS code. The simulations include the effects of 1D plasma profiles and particle recycling, and the framework allows for testing the robustness and performance of the controllers in various scenarios, including confinement changes, impurity content changes, and actuators faults.

  8. Sensitivity method for integrated structure/active control law design

    NASA Technical Reports Server (NTRS)

    Gilbert, Michael G.

    1987-01-01

    The development is described of an integrated structure/active control law design methodology for aeroelastic aircraft applications. A short motivating introduction to aeroservoelasticity is given along with the need for integrated structures/controls design algorithms. Three alternative approaches to development of an integrated design method are briefly discussed with regards to complexity, coordination and tradeoff strategies, and the nature of the resulting solutions. This leads to the formulation of the proposed approach which is based on the concepts of sensitivity of optimum solutions and multi-level decompositions. The concept of sensitivity of optimum is explained in more detail and compared with traditional sensitivity concepts of classical control theory. The analytical sensitivity expressions for the solution of the linear, quadratic cost, Gaussian (LQG) control problem are summarized in terms of the linear regulator solution and the Kalman Filter solution. Numerical results for a state space aeroelastic model of the DAST ARW-II vehicle are given, showing the changes in aircraft responses to variations of a structural parameter, in this case first wing bending natural frequency.

  9. Approach and withdrawal motivation in schizophrenia: an examination of frontal brain asymmetric activity.

    PubMed

    Horan, William P; Wynn, Jonathan K; Mathis, Ian; Miller, Gregory A; Green, Michael F

    2014-01-01

    Although motivational disturbances are common in schizophrenia, their neurophysiological and psychological basis is poorly understood. This electroencephalography (EEG) study examined the well-established motivational direction model of asymmetric frontal brain activity in schizophrenia. According to this model, relative left frontal activity in the resting EEG reflects enhanced approach motivation tendencies, whereas relative right frontal activity reflects enhanced withdrawal motivation tendencies. Twenty-five schizophrenia outpatients and 25 healthy controls completed resting EEG assessments of frontal asymmetry in the alpha frequency band (8-12 Hz), as well as a self-report measure of behavioral activation and inhibition system (BIS/BAS) sensitivity. Patients showed an atypical pattern of differences from controls. On the EEG measure patients failed to show the left lateralized activity that was present in controls, suggesting diminished approach motivation. On the self-report measure, patients reported higher BIS sensitivity than controls, which is typically interpreted as heightened withdrawal motivation. EEG asymmetry scores did not significantly correlate with BIS/BAS scores or with clinical symptom ratings among patients. The overall pattern suggests a motivational disturbance in schizophrenia characterized by elements of both diminished approach and elevated withdrawal tendencies.

  10. Active control of sound transmission through partitions composed of discretely controlled modules

    NASA Astrophysics Data System (ADS)

    Leishman, Timothy W.

    This thesis provides a detailed theoretical and experimental investigation of active segmented partitions (ASPs) for the control of sound transmission. ASPs are physically segmented arrays of interconnected acoustically and structurally small modules that are discretely controlled using electronic controllers. Theoretical analyses of the thesis first address physical principles fundamental to ASP modeling and experimental measurement techniques. Next, they explore specific module configurations, primarily using equivalent circuits. Measured normal-incidence transmission losses and related properties of experimental ASPs are determined using plane wave tubes and the two-microphone transfer function technique. A scanning laser vibrometer is also used to evaluate distributed transmitting surface vibrations. ASPs have the inherent potential to provide excellent active sound transmission control (ASTC) through lightweight structures, using very practical control strategies. The thesis analyzes several unique ASP configurations and evaluates their abilities to produce high transmission losses via global minimization of normal transmitting surface vibrations. A novel dual diaphragm configuration is shown to employ this strategy particularly well. It uses an important combination of acoustical actuation and mechano-acoustical segmentation to produce exceptionally high transmission loss (e.g., 50 to 80 dB) over a broad frequency range-including lower audible frequencies. Such performance is shown to be comparable to that produced by much more massive partitions composed of thick layers of steel or concrete and sand. The configuration uses only simple localized error sensors and actuators, permitting effective use of independent single-channel controllers in a decentralized format. This work counteracts the commonly accepted notion that active vibration control of partitions is an ineffective means of controlling sound transmission. With appropriate construction, actuation

  11. An Expert System Approach to Large Space Systems Control

    DTIC Science & Technology

    1988-10-01

    ISPONSORING 8b. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORGANIZATION Of appil ,k) FOSR F49620-87- C --0105 8¢. ADDRESS (CRtY, Stat...oo...0 - An Expert System Approach To Large Space Systems Control Octobe 1988Accession For NTIS R& DTIC TAB C . GartrmII Unannounced E W...4.4.1 Case A: I Newton Harmonic Wave with a Frequency of 0.14 Hz 4-12 4.4.2 Case B: 1 Newton Impulse at x = 2.5 m 4-13 4.4.3 Case C : Traveling Wave with

  12. The 4-D approach to visual control of autonomous systems

    NASA Technical Reports Server (NTRS)

    Dickmanns, Ernst D.

    1994-01-01

    Development of a 4-D approach to dynamic machine vision is described. Core elements of this method are spatio-temporal models oriented towards objects and laws of perspective projection in a foward mode. Integration of multi-sensory measurement data was achieved through spatio-temporal models as invariants for object recognition. Situation assessment and long term predictions were allowed through maintenance of a symbolic 4-D image of processes involving objects. Behavioral capabilities were easily realized by state feedback and feed-foward control.

  13. Amplitude Scaling of Active Separation Control

    NASA Technical Reports Server (NTRS)

    Stalnov, Oksana; Seifert, Avraham

    2010-01-01

    Three existing and two new excitation magnitude scaling options for active separation control at Reynolds numbers below one Million. The physical background for the scaling options was discussed and their relevance was evaluated using two different sets of experimental data. For F+ approx. 1, 2D excitation: a) The traditional VR and C(mu) - do not scale the data. b) Only the Re*C(mu) is valid. This conclusion is also limited for positive lift increment.. For F+ > 10, 3D excitation, the Re corrected C(mu), the St corrected velocity ratio and the vorticity flux coefficient, all scale the amplitudes equally well. Therefore, the Reynolds weighted C(mu) is the preferred choice, relevant to both excitation modes. Incidence also considered, using Ue from local Cp.

  14. Ribosome-dependent activation of stringent control

    PubMed Central

    Gordiyenko, Yuliya; Ramakrishnan, V.

    2016-01-01

    In order to survive, bacteria continually sense, and respond to, environmental fluctuations. Stringent control represents a key bacterial stress response to nutrient starvation1,2 that leads to a rapid and comprehensive reprogramming of metabolic and transcriptional patterns3. In general, transcription of genes for growth and proliferation are down-regulated, while those important for survival and virulence are favored4. Amino acid starvation is sensed by depletion of the aminoacyl-tRNA pools5, which results in accumulation of ribosomes stalled with non-aminoacylated (uncharged) tRNA in the ribosomal A-site6,7. RelA is recruited to stalled ribosomes, and activated to synthesize a hyperphosphorylated guanosine analog, (p)ppGpp8, which acts as a pleiotropic second messenger. However, structural information for how RelA recognizes stalled ribosomes and discriminates against aminoacylated tRNAs is missing. Here, we present the electron cryo-microscopy (cryo-EM) structure of RelA bound to the bacterial ribosome stalled with uncharged tRNA. The structure reveals that RelA utilizes a distinct binding site compared to the translational factors, with a multi-domain architecture that wraps around a highly distorted A-site tRNA. The TGS domain of RelA binds the CCA tail to orient the free 3’ hydroxyl group of the terminal adenosine towards a β-strand, such that an aminoacylated tRNA at this position would be sterically precluded. The structure supports a model where association of RelA with the ribosome suppresses auto-inhibition to activate synthesis of (p)ppGpp and initiate the stringent response. Since stringent control is responsible for the survival of pathogenic bacteria under stress conditions, and contributes to chronic infections and antibiotic tolerance, RelA represents a good target for the development of novel antibacterial therapeutics. PMID:27279228

  15. Chemical and biological approaches for mycotoxin control: a review.

    PubMed

    Edlayne, Gonçalez; Simone, Aquino; Felicio, Joana D

    2009-06-01

    Mycotoxins are metabolites and toxic substances produced by certain filamentous fungi that frequently contaminate food and agriculture commodities, which cause disease in animals or man. The toxigenic fungi belong to mainly three genera: Aspergillus, Penicillium and Fusarium. Examples of mycotoxins of greatest public health and agroeconomic significance include aflatoxins, ochratoxins, trichothecenes, zearalenone, fumonisins, patulin and ergot alkaloids. Commodities susceptible to direct contamination with mycotoxins include nuts, oilseeds and grains. Chemical and biological treatments have been attempted to minimize the risk of mycotoxins contamination or eliminate the fungi of food and feeds. One way to prevent or interfere with fungal growth and mycotoxin production is by use of synthetic or natural agents. Bacteria have been studied to control the mycotoxins production and fungal growth in food. Plant genotypes resistant to infection by toxigenic fungi have been also studied. This review will approach same patented methods applied to degrade, prevent and control of mycotoxins in food and feeds.

  16. Anorexia nervosa and bulimia: an activity-oriented approach.

    PubMed

    Giles, G M

    1985-08-01

    In recent years, there has been a growing trend away from a dogmatic adherence to any one approach in the treatment of eating disorders. This paper adds the new element of practice in relation to cognitive change. The activity-oriented approach outlined here stresses that patients with anorexia nervosa or bulimia must maintain responsibility for their own food intake throughout treatment. The key role of the occupational therapist in the treatment team is outlined, and suggestions for assessment and management of this type of patient are given.

  17. A modern control approach to the design of the SPS control system

    NASA Technical Reports Server (NTRS)

    Gran, R.

    1980-01-01

    The structural dynamics of the solar power satellite were considered. The requirements on the vibration of the microwave antenna and the possibility of thermal induced vibration and severe structural-thermal interactions were considered. The possibility of using an active control system and modern control methods to mitigate structural problems is discussed.

  18. New photochemical tools for controlling neuronal activity

    PubMed Central

    Kramer, Richard H.; Fortin, Doris L.; Trauner, Dirk

    2009-01-01

    Neurobiology has entered a new era in which optical methods are challenging electrophysiological techniques for their value in measuring and manipulating neuronal activity. This change is occurring largely because of the development of new photochemical tools, some synthesized by chemists and some provided by nature. This review is focused on the three types of photochemical tools for neuronal control that have emerged in recent years. Caged neurotransmitters, including caged glutamate, are synthetic molecules that enable highly localized activation of neurotransmitter receptors in response to light. Natural photosensitive proteins, including channelrhodopsin-2 and halorhodopsin, can be exogenously expressed in neurons and enable rapid photocontrol of action potential firing. Synthetic small-molecule photoswitches can bestow light-sensitivity on native or exogenously expressed proteins, including K+ channels and glutamate receptors, allowing photocontrol of action potential firing and synaptic events. At a rapid pace, these tools are being improved and new tools are being introduced, thanks to molecular biology and synthetic chemistry. The three families of photochemical tools have different capabilities and uses, but they all share in enabling precise and non-invasive exploration of neural function with light. PMID:19828309

  19. Multi-sensor control for 6-axis active vibration isolation

    NASA Astrophysics Data System (ADS)

    Thayer, Douglas Gary

    The goal of this research is to look at the two different parts of the challenge of active vibration isolation. First is the hardware that will be used to accomplish the task and improve performance. The cubic hexapod, or Stewart platform, has become a popular solution to the problem because of its ability to provide 6-axis vibration isolation with a relatively simple configuration. A number of these hexapods have been constructed at different research facilities around the country to address different missions, each with their own approach. Hood Technology Corporation and the University of Washington took the lessons learned from these designs and developed a new hexapod that addresses the requirements of the Jet Propulsion Laboratory's planned space borne interferometry missions. This system has unique mechanical design details and is built with 4 sensors in each strut. This, along with a real time computer to implement controllers, allows for a great deal of flexibility in controller design and research into sensor selection. Other unique design features include a very soft axial stiffness, a custom designed voice coil actuator with a large displacement capability and elastomeric flexures both for guiding the actuator and providing pivot points on each strut. The second part, and the primary area of this research, is to examine multi-sensor control strategies in an effort to improve the performance of the controllers, their stability and/or how implementable they are. Up to this point, the primary method of control for systems of this type has been classical, designing single-input, single output controller loops to be closed around each strut. But because of the geometry of the hexapod and the different problems that can occur with some sensors, the classical approach is limited in what it can accomplish. This research shows the benefits to be gained by going to a multiple sensor controller and implementing controllers that are designed using a frequency

  20. Improving the vibration suppression capabilities of a magneto-rheological damper using hybrid active and semi-active control

    NASA Astrophysics Data System (ADS)

    Ullah Khan, Irfan; Wagg, David; Sims, Neil D.

    2016-08-01

    This paper presents a new hybrid active and semi-active control method for vibration suppression in flexible structures. The method uses a combination of a semi-active device and an active control actuator situated elsewhere in the structure to suppress vibrations. The key novelty is to use the hybrid controller to enable the magneto-rheological damper to achieve a performance as close to a fully active device as possible. This is achieved by ensuring that the active actuator can assist the magneto-rheological damper in the regions where energy is required. In addition, the hybrid active and semi-active controller is designed to minimize the switching of the semi-active controller. The control framework used is the immersion and invariance control technique in combination with sliding mode control. A two degree-of-freedom system with lightly damped resonances is used as an example system. Both numerical and experimental results are generated for this system, and then compared as part of a validation study. The experimental system uses hardware-in-the-loop to simulate the effect of both the degrees-of-freedom. The results show that the concept is viable both numerically and experimentally, and improved vibration suppression results can be obtained for the magneto-rheological damper that approach the performance of an active device.

  1. Implementation of CPFD to Control Active and Passive Airfoil Propulsion

    NASA Astrophysics Data System (ADS)

    Young, Jay; Asselin, Daniel; Williamson, Charles

    2016-11-01

    The fluid dynamics of biologically-inspired flapping propulsion provides a fertile testing ground for the field of unsteady aerodynamics, serving as important groundwork for the design and development of fast, mobile underwater vehicles and flapping-wing micro air vehicles (MAVs). There has been a recent surge of interest in these technologies as they provide low cost, compact, and maneuverable means for terrain mapping, search and rescue operations, and reconnaissance. Propulsion by unsteady motions has been fundamentally modeled with an airfoil that heaves and pitches, and previous work has been done to show that actively controlling these motions can generate high thrust and efficiency (Read, Hover & Triantafyllou 2003). In this study, we examine the performance of an airfoil with an actuated heave motion coupled with a passively controlled pitch motion created by simulating the presence of a torsional spring using our cyber-physical fluid dynamics (CPFD) approach (Mackowski & Williamson 2011, 2015, 2016). By using passively controlled pitch, we have effectively eliminated an actuator, decreasing cost and mass, an important step for developing efficient vehicles. In many cases, we have achieved comparable or superior thrust and efficiency values to those obtained using two actively controlled degrees of freedom. This work was supported by the National Science Foundation and the Air Force Office of Scientific Research Grant No. FA9550-15-1-0243, monitored by Dr. Douglas Smith.

  2. Supramolecular Approaches to Nanoscale Morphological Control in Organic Solar Cells

    PubMed Central

    Haruk, Alexander M.; Mativetsky, Jeffrey M.

    2015-01-01

    Having recently surpassed 10% efficiency, solar cells based on organic molecules are poised to become a viable low-cost clean energy source with the added advantages of mechanical flexibility and light weight. The best-performing organic solar cells rely on a nanostructured active layer morphology consisting of a complex organization of electron donating and electron accepting molecules. Although much progress has been made in designing new donor and acceptor molecules, rational control over active layer morphology remains a central challenge. Long-term device stability is another important consideration that needs to be addressed. This review highlights supramolecular strategies for generating highly stable nanostructured organic photovoltaic active materials by design. PMID:26110382

  3. Active control of bias for the control of posture and movement.

    PubMed

    Guigon, Emmanuel

    2010-08-01

    Posture and movement are fundamental, intermixed components of motor coordination. Current approaches consider either that 1) movement is an active, anticipatory process and posture is a passive feedback process or 2) movement and posture result from a common passive process. In both cases, the presence of a passive component renders control scarcely robust and stable in the face of transmission delays and low feedback gains. Here we show in a model that posture and movement could result from the same active process: an optimal feedback control that drives the body from its estimated state to its goal in a given (planning) time by acting through muscles on the insertion position (bias) of compliant linkages (tendons). Computer simulations show that iteration of this process in the presence of noise indifferently produces realistic postural sway, fast goal-directed movements, and natural transitions between posture and movement.

  4. Dynamics and control of multibody systems: An approach with application

    NASA Astrophysics Data System (ADS)

    Grewal, A.; Modi, V. J.

    1996-09-01

    The paper focuses on the study of the dynamics and control of large flexible space structures, comprised of sub-assemblies, a subject of considerable contemporary interest. To begin with, a relatively general Lagrangian formulation of the problem is developed. The governing equations are non-linear, non-autonomous, coupled and extremely lengthy even in matrix notation. Next, an efficient computer code is developed and the versatility of the program illustrated through a study of the dynamics of the First Element Launch (FEL) configuration of the Space Station Freedom, now superseded by the International Space Station Alpha. The response of the FEL is obtained for two critical disturbances: (a) docking of the Space Shuttle; and (b) maneuver of the onboard mobile manipulator system (MSS). The study clearly demonstrates a need for active control. To that end, robust control of the rigid body motion of the FEL configuration using the LQG/LTR procedure is demonstrated. The controller designed using the simplified linear model, proves to be effective in regulating librational disturbances. Such a global approach—formulation, numerical code, dynamics and control—can serve as a powerful tool to gain comprehensive understanding of the interactions of the dynamics and thus aid in the development of effective and efficient control systems.

  5. Active Piezoelectric Vibration Control of Subscale Composite Fan Blades

    NASA Technical Reports Server (NTRS)

    Duffy, Kirsten P.; Choi, Benjamin B.; Provenza, Andrew J.; Min, James B.; Kray, Nicholas

    2012-01-01

    As part of the Fundamental Aeronautics program, researchers at NASA Glenn Research Center (GRC) are investigating new technologies supporting the development of lighter, quieter, and more efficient fans for turbomachinery applications. High performance fan blades designed to achieve such goals will be subjected to higher levels of aerodynamic excitations which could lead to more serious and complex vibration problems. Piezoelectric materials have been proposed as a means of decreasing engine blade vibration either through a passive damping scheme, or as part of an active vibration control system. For polymer matrix fiber composite blades, the piezoelectric elements could be embedded within the blade material, protecting the brittle piezoceramic material from the airflow and from debris. To investigate this idea, spin testing was performed on two General Electric Aviation (GE) subscale composite fan blades in the NASA GRC Dynamic Spin Rig Facility. The first bending mode (1B) was targeted for vibration control. Because these subscale blades are very thin, the piezoelectric material was surface-mounted on the blades. Three thin piezoelectric patches were applied to each blade two actuator patches and one small sensor patch. These flexible macro-fiber-composite patches were placed in a location of high resonant strain for the 1B mode. The blades were tested up to 5000 rpm, with patches used as sensors, as excitation for the blade, and as part of open- and closed-loop vibration control. Results show that with a single actuator patch, active vibration control causes the damping ratio to increase from a baseline of 0.3% critical damping to about 1.0% damping at 0 RPM. As the rotor speed approaches 5000 RPM, the actively controlled blade damping ratio decreases to about 0.5% damping. This occurs primarily because of centrifugal blade stiffening, and can be observed by the decrease in the generalized electromechanical coupling with rotor speed.

  6. Potential International Approaches to Ownership/Control of Human Genetic Resources.

    PubMed

    Rhodes, Catherine

    2016-09-01

    In its governance activities for genetic resources, the international community has adopted various approaches to their ownership, including: free access; common heritage of mankind; intellectual property rights; and state sovereign rights. They have also created systems which combine elements of these approaches. While governance of plant and animal genetic resources is well-established internationally, there has not yet been a clear approach selected for human genetic resources. Based on assessment of the goals which international governance of human genetic resources ought to serve, and the implications for how they will be accessed and utilised, it is argued that common heritage of mankind will be the most appropriate approach to adopt to their ownership/control. It does this with the aim of stimulating discussion in this area and providing a starting point for deeper consideration of how a common heritage of mankind, or similar, regime for human genetic resources would function and be implemented.

  7. Passive and active adaptive management: approaches and an example.

    PubMed

    Williams, Byron K

    2011-05-01

    Adaptive management is a framework for resource conservation that promotes iterative learning-based decision making. Yet there remains considerable confusion about what adaptive management entails, and how to actually make resource decisions adaptively. A key but somewhat ambiguous distinction in adaptive management is between active and passive forms of adaptive decision making. The objective of this paper is to illustrate some approaches to active and passive adaptive management with a simple example involving the drawdown of water impoundments on a wildlife refuge. The approaches are illustrated for the drawdown example, and contrasted in terms of objectives, costs, and potential learning rates. Some key challenges to the actual practice of AM are discussed, and tradeoffs between implementation costs and long-term benefits are highlighted.

  8. Passive and active adaptive management: Approaches and an example

    USGS Publications Warehouse

    Williams, B.K.

    2011-01-01

    Adaptive management is a framework for resource conservation that promotes iterative learning-based decision making. Yet there remains considerable confusion about what adaptive management entails, and how to actually make resource decisions adaptively. A key but somewhat ambiguous distinction in adaptive management is between active and passive forms of adaptive decision making. The objective of this paper is to illustrate some approaches to active and passive adaptive management with a simple example involving the drawdown of water impoundments on a wildlife refuge. The approaches are illustrated for the drawdown example, and contrasted in terms of objectives, costs, and potential learning rates. Some key challenges to the actual practice of AM are discussed, and tradeoffs between implementation costs and long-term benefits are highlighted. ?? 2010 Elsevier Ltd.

  9. Escape rate of active particles in the effective equilibrium approach

    NASA Astrophysics Data System (ADS)

    Sharma, A.; Wittmann, R.; Brader, J. M.

    2017-01-01

    The escape rate of a Brownian particle over a potential barrier is accurately described by the Kramers theory. A quantitative theory explicitly taking the activity of Brownian particles into account has been lacking due to the inherently out-of-equilibrium nature of these particles. Using an effective equilibrium approach [Farage et al., Phys. Rev. E 91, 042310 (2015), 10.1103/PhysRevE.91.042310] we study the escape rate of active particles over a potential barrier and compare our analytical results with data from direct numerical simulation of the colored noise Langevin equation. The effective equilibrium approach generates an effective potential that, when used as input to Kramers rate theory, provides results in excellent agreement with the simulation data.

  10. Functional toxicology: a new approach to detect biologically active xenobiotics.

    PubMed Central

    McLachlan, J A

    1993-01-01

    The pervasiveness of chemicals in the environment with estrogenic activity and other biological functions recommends the development of new approaches to monitor and study them. Chemicals can be screened for activity in vitro using a panel of human or animal cells that have been transfected with a specific receptor and reporter gene; for example, the estrogen receptor. By using a variety of different receptors, the screening of xenobiotics for biological functions can be broad. Chemicals could then be classified by their function in vitro which, in some cases, may be a useful guide for toxicological studies. Images Figure 1. PMID:8119246

  11. System identification and control of the JPL active structure

    NASA Technical Reports Server (NTRS)

    Fanson, J. L.; Lurie, B. J.; O'Brien, J. F.; Chu, C.-C.; Smith, R. S.

    1991-01-01

    This paper describes recent advances in structural quieting technology as applied to active truss structures intended for high precision space based optics applications. Collocated active damping control loops are designed in order to impedance match piezoelectric active members to the structure. Noncollocated control loops are also studied in relation to controlling lightly damped structures.

  12. A parameter optimization approach to controller partitioning for integrated flight/propulsion control application

    NASA Technical Reports Server (NTRS)

    Schmidt, Phillip; Garg, Sanjay; Holowecky, Brian

    1992-01-01

    A parameter optimization framework is presented to solve the problem of partitioning a centralized controller into a decentralized hierarchical structure suitable for integrated flight/propulsion control implementation. The controller partitioning problem is briefly discussed and a cost function to be minimized is formulated, such that the resulting 'optimal' partitioned subsystem controllers will closely match the performance (including robustness) properties of the closed-loop system with the centralized controller while maintaining the desired controller partitioning structure. The cost function is written in terms of parameters in a state-space representation of the partitioned sub-controllers. Analytical expressions are obtained for the gradient of this cost function with respect to parameters, and an optimization algorithm is developed using modern computer-aided control design and analysis software. The capabilities of the algorithm are demonstrated by application to partitioned integrated flight/propulsion control design for a modern fighter aircraft in the short approach to landing task. The partitioning optimization is shown to lead to reduced-order subcontrollers that match the closed-loop command tracking and decoupling performance achieved by a high-order centralized controller.

  13. A parameter optimization approach to controller partitioning for integrated flight/propulsion control application

    NASA Technical Reports Server (NTRS)

    Schmidt, Phillip H.; Garg, Sanjay; Holowecky, Brian R.

    1993-01-01

    A parameter optimization framework is presented to solve the problem of partitioning a centralized controller into a decentralized hierarchical structure suitable for integrated flight/propulsion control implementation. The controller partitioning problem is briefly discussed and a cost function to be minimized is formulated, such that the resulting 'optimal' partitioned subsystem controllers will closely match the performance (including robustness) properties of the closed-loop system with the centralized controller while maintaining the desired controller partitioning structure. The cost function is written in terms of parameters in a state-space representation of the partitioned sub-controllers. Analytical expressions are obtained for the gradient of this cost function with respect to parameters, and an optimization algorithm is developed using modern computer-aided control design and analysis software. The capabilities of the algorithm are demonstrated by application to partitioned integrated flight/propulsion control design for a modern fighter aircraft in the short approach to landing task. The partitioning optimization is shown to lead to reduced-order subcontrollers that match the closed-loop command tracking and decoupling performance achieved by a high-order centralized controller.

  14. Cyber secure systems approach for NPP digital control systems

    SciTech Connect

    McCreary, T. J.; Hsu, A.

    2006-07-01

    Whether fossil or nuclear power, the chief operations goal is to generate electricity. The heart of most plant operations is the I and C system. With the march towards open architecture, the I and C system is more vulnerable than ever to system security attacks (denial of service, virus attacks and others), thus jeopardizing plant operations. Plant staff must spend large amounts of time and money setting up and monitoring a variety of security strategies to counter the threats and actual attacks to the system. This time and money is a drain on the financial performance of a plant and distracts valuable operations resources from their real goals: product. The pendulum towards complete open architecture may have swung too far. Not all aspects of proprietary hardware and software are necessarily 'bad'. As the aging U.S. fleet of nuclear power plants starts to engage in replacing legacy control systems, and given the on-going (and legitimate) concern about the security of present digital control systems, decisions about how best to approach cyber security are vital to the specification and selection of control system vendors for these upgrades. The authors maintain that utilizing certain resources available in today's digital technology, plant control systems can be configured from the onset to be inherently safe, so that plant staff can concentrate on the operational issues of the plant. The authors postulate the concept of the plant I and C being bounded in a 'Cyber Security Zone' and present a design approach that can alleviate the concern and cost at the plant level of dealing with system security strategies. Present approaches through various IT cyber strategies, commercial software, and even postulated standards from various industry/trade organizations are almost entirely reactive and simply add to cost and complexity. This Cyber Security Zone design demonstrates protection from the four classes of cyber security attacks: 1)Threat from an intruder attempting to

  15. Kinetic approach for evaluation of total antioxidant activity.

    PubMed

    Karyakina, Elena E; Vokhmyanina, Darya V; Sizova, Natalya V; Sabitov, Aytugan N; Borisova, Anastasiya V; Sazontova, Tatyana G; Arkhipenko, Yury V; Tkachuk, Vsevolod A; Zolotov, Yury A; Karyakin, Arkady A

    2009-12-15

    We propose a novel approach for assessment of total antioxidant activity by monitoring kinetics of hydrogen peroxide (H(2)O(2)) scavenging after its injection into liquid sample under study. H(2)O(2) is known to be the strongest oxidant, really presented in human body in contrast to the majority of the model oxidative systems used for evaluation of antioxidant activity. In addition, kinetic approach, being more informative than the commonly used determination of the final product, obviously provides better discrimination of potential antioxidants. Prussian Blue based sensor due to its high sensitivity and operational stability allowed to monitor kinetics of hydrogen peroxide consumption in turbid and colored samples. The pseudo-first order kinetic constants of hydrogen peroxide scavenging in the presence of different food additives correlated with total antioxidant activity of these samples evaluated via standard procedure based on lipid peroxidation. However, in contrast to the standard method, the proposed kinetic approach is expressed and does not require fresh biological tissues.

  16. Effect of control surface mass unbalance on the stability of a closed-loop active control system

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1989-01-01

    The effects on stability of inertial forces arising from closed-loop activation of mass-unbalanced control surfaces are studied analytically using inertial energy approach, similar to the aerodynamic energy approach used for flutter suppression. The limitations of a single control surface like a leading-edge (LE) control or a trailing-edge (TE) control are demonstrated and compared to the superior combined LE-TE mass unbalanced system. It is shown that a spanwise section for sensor location can be determined which ensures minimum sensitivity to the mode shapes of the aircraft. It is shown that an LE control exhibits compatibility between inertial stabilization and aerodynamic stabilization, and that a TE control lacks such compatibility. The results of the present work should prove valuable, both for the purpose of flutter suppression using mass unbalanced control surfaces, or for the stabilization of structural modes of large space structures by means of inertial forces.

  17. Optimal control based on adaptive model reduction approach to control transfer phenomena

    NASA Astrophysics Data System (ADS)

    Oulghelou, Mourad; Allery, Cyrille

    2017-01-01

    The purpose of optimal control is to act on a set of parameters characterizing a dynamical system to achieve a target dynamics. In order to reduce CPU time and memory storage needed to perform control on evolution systems, it is possible to use reduced order models (ROMs). The mostly used one is the Proper Orthogonal Decomposition (POD). However the bases constructed in this way are sensitive to the configuration of the dynamical system. Consequently, the need of full simulations to build a basis for each configuration is time consuming and makes that approach still relatively expensive. In this paper, to overcome this difficulty we suggest to use an adequate bases interpolation method. It consists in computing the associated bases to a distribution of control parameters. These bases are afterwards called in the control algorithm to build a reduced basis adapted to a given control parameter. This interpolation method involves results of the calculus of Geodesics on Grassmann manifold.

  18. The Difficult-to-Control Asthmatic: A Systematic Approach

    PubMed Central

    2006-01-01

    With the judicious use of inhaled corticosteroids, β2 agonists, and leukotriene modifiers, most patients with asthma are easily controlled and managed. However, approximately 5% of asthmatics do not respond to standard therapy and are classified as "difficult to control." [1] Typically, these are patients who complain of symptoms interfering with daily living despite long-term treatment with inhaled corticosteroids in doses up to 2,000 μg daily. Many factors can contribute to poor response to conventional therapy, and especially for these patients, a systematic approach is needed to identify the underlying causes. First, the diagnosis of asthma and adherence to the medication regimen should be confirmed. Next, potential persisting exacerbating triggers need to be identified and addressed. Concomitant disorders should be discovered and treated. Lastly, the impact and implications of socioeconomic and psychological factors on disease control can be significant and should be acknowledged and discussed with the individual patient. Less conventional and novel strategies for treating corticosteroid-resistant asthma do exist. However, their use is based on small studies that do not meet evidence-based criteria; therefore, it is essential to sort through and address the above issues before reverting to other therapy. PMID:20525155

  19. A multiple objective optimization approach to quality control

    NASA Technical Reports Server (NTRS)

    Seaman, Christopher Michael

    1991-01-01

    The use of product quality as the performance criteria for manufacturing system control is explored. The goal in manufacturing, for economic reasons, is to optimize product quality. The problem is that since quality is a rather nebulous product characteristic, there is seldom an analytic function that can be used as a measure. Therefore standard control approaches, such as optimal control, cannot readily be applied. A second problem with optimizing product quality is that it is typically measured along many dimensions: there are many apsects of quality which must be optimized simultaneously. Very often these different aspects are incommensurate and competing. The concept of optimality must now include accepting tradeoffs among the different quality characteristics. These problems are addressed using multiple objective optimization. It is shown that the quality control problem can be defined as a multiple objective optimization problem. A controller structure is defined using this as the basis. Then, an algorithm is presented which can be used by an operator to interactively find the best operating point. Essentially, the algorithm uses process data to provide the operator with two pieces of information: (1) if it is possible to simultaneously improve all quality criteria, then determine what changes to the process input or controller parameters should be made to do this; and (2) if it is not possible to improve all criteria, and the current operating point is not a desirable one, select a criteria in which a tradeoff should be made, and make input changes to improve all other criteria. The process is not operating at an optimal point in any sense if no tradeoff has to be made to move to a new operating point. This algorithm ensures that operating points are optimal in some sense and provides the operator with information about tradeoffs when seeking the best operating point. The multiobjective algorithm was implemented in two different injection molding scenarios

  20. A numerical approach to controller design for the ACES facility

    NASA Technical Reports Server (NTRS)

    Frazier, W. Garth; Irwin, R. Dennis

    1993-01-01

    In recent years the employment of active control techniques for improving the performance of systems involving highly flexible structures has become a topic of considerable research interest. Most of these systems are quite complicated, using multiple actuators and sensors, and possessing high order models. The majority of analytical controller synthesis procedures capable of handling multivariable systems in a systematic way require considerable insight into the underlying mathematical theory to achieve a successful design. This insight is needed in selecting the proper weighting matrices or weighting functions to cast what is naturally a multiple constraint satisfaction problem into an unconstrained optimization problem. Although designers possessing considerable experience with these techniques have a feel for the proper choice of weights, others may spend a significant amount of time attempting to find an acceptable solution. Another disadvantage of such procedures is that the resulting controller has an order greater than or equal to that of the model used for the design. Of course, the order of these controllers can often be reduced, but again this requires a good understanding of the theory involved.

  1. Aerodynamic Control using Distributed Active Bleed

    NASA Astrophysics Data System (ADS)

    Kearney, John; Glezer, Ari

    2015-11-01

    The global aerodynamic loads on a stationary and pitching airfoil at angles of attack beyond the static and dynamic stall margins, respectively are controlled in wind tunnel experiments using regulated distributed bleed driven by surface pressure differences. High-speed PIV and proper orthogonal decomposition of the vorticity flux on the static airfoil show that the bleed engenders trains of discrete vortices that advect along the surface and are associated with a local instability that is manifested by a time-averaged bifurcation of the vorticity layer near the bleed outlets and alters the vorticity flux over the airfoil and thereby the aerodynamic loads. Active bleed is used on a dynamically pitching airfoil (at reduced frequencies up to k = 0.42) to modulate the evolution of vorticity concentrations during dynamic stall. Time-periodic bleed improved the pitch stability by reducing adverse pitching moment (``negative damping'') that can precipitate structural instabilities. At the same time, the maintains the cycle-average loads to within 5% of the base flow levels by segmenting the vorticity layer during upstroke and promoting early flow attachment during downstroke segments of the pitch cycle. Supported by Georgia Tech VLRCOE.

  2. Reaching and educating the global tobacco control community: innovative approaches to tobacco control training.

    PubMed

    Stillman, Frances; Wipfli, Heather; Samet, Jonathan

    2006-01-01

    To slow and end the growing global burden of tobacco-related death and disease, schools of public health need to provide tobacco control education and training for public health professionals generally, and for the next generation of tobacco control professionals in low- and middle-income countries specifically. As the tobacco epidemic continues to grow, there is an increasing need for training to develop the research and intervention skills required to stem the epidemic and reduce the inevitable burden of disease and death. A wide range of educational approaches has been developed to increase tobacco control educational capacity in high-, middle-, and low-income countries, including traditional on-site classes, on-line courses, open source courseware, summer school programs, and training workshops. This article provides a perspective on the education and training needs of tobacco control researchers around the world and reviews the strengths and weaknesses of education and training approaches currently being used in tobacco control by schools of public health. In each case, we draw on the experience of the Johns Hopkins Bloomberg School of Public Health in educating national and international audiences in tobacco control.

  3. Connections among several chaos feedback control approaches and chaotic vibration control of mechanical systems

    NASA Astrophysics Data System (ADS)

    Yang, Dixiong; Zhou, Jilei

    2014-11-01

    This study reveals the essential connections among several popular chaos feedback control approaches, such as delayed feedback control (DFC), stability transformation method (STM), adaptive adjustment method (AAM), parameter adjustment method, relaxed Newton method, and speed feedback control method (SFCM), etc. Meanwhile, the generality and practical applicability of these approaches are evaluated and compared. It is shown that for discrete chaotic maps, STM can be regarded as a kind of predictive feedback control, and AAM is actually a special case of STM which is merely effective for a particular dynamical system. The parameter adjustment method is only a different expression of the relaxed Newton method, and both of them represent just one search direction of STM, i.e., the gradient direction. Moreover, the intrinsic relation between the STM and SFCM for controlling the equilibrium of continuous autonomous systems is investigated, indicating that STM can be viewed as a special form of the SFCM. Finally, both the STM and SFCM are extended to control the chaotic vibrations of non-autonomous mechanical systems effectively.

  4. HIV eradication: combinatorial approaches to activate latent viruses.

    PubMed

    De Crignis, Elisa; Mahmoudi, Tokameh

    2014-11-21

    The concept of eradication of the Human Immune Deficiency Virus (HIV) from infected patients has gained much attention in the last few years. While combination Anti-Retroviral Therapy (c-ART) has been extremely effective in suppressing viral replication, it is not curative. This is due to the presence of a reservoir of latent HIV infected cells, which persist in the presence of c-ART. Recently, pharmaceutical approaches have focused on the development of molecules able to induce HIV-1 replication from latently infected cells in order to render them susceptible to viral cytopathic effects and host immune responses. Alternative pathways and transcription complexes function to regulate the activity of the HIV promoter and might serve as molecular targets for compounds to activate latent HIV. A combined therapy coupling various depressors and activators will likely be the most effective in promoting HIV replication while avoiding pleiotropic effects at the cellular level. Moreover, in light of differences among HIV subtypes and variability in integration sites, the combination of multiple agents targeting multiple pathways will increase likelihood of therapeutic effectiveness and prevent mutational escape. This review provides an overview of the mechanisms that can be targeted to induce HIV activation focusing on potential combinatorial approaches.

  5. The importance of behavior theory in control system modeling of physical activity sensor data.

    PubMed

    Riley, William T; Martin, Cesar A; Rivera, Daniel E

    2014-01-01

    Among health behaviors, physical activity has the most extensive record of research using passive sensors. Control systems and other system dynamic approaches have long been considered applicable for understanding human behavior, but only recently has the technology provided the precise and intensive longitudinal data required for these analytic approaches. Although sensors provide intensive data on the patterns and variations of physical activity over time, the influences of these variations are often unmeasured. Health behavior theories provide an explanatory framework of the putative mediators of physical activity changes. Incorporating the intensive longitudinal measurement of these theoretical constructs is critical to improving the fit of control system model of physical activity and for advancing behavioral theory. Theory-based control models also provide guidance on the nature of the controllers which serve as the basis for just-in-time adaptive interventions based on these control system models.

  6. Biogas Production Modelling: A Control System Engineering Approach

    NASA Astrophysics Data System (ADS)

    Stollenwerk, D.; Rieke, C.; Dahmen, M.; Pieper, M.

    2016-03-01

    Due to the Renewable Energy Act, in Germany it is planned to increase the amount of renewable energy carriers up to 60%. One of the main problems is the fluctuating supply of wind and solar energy. Here biogas plants provide a solution, because a demand-driven supply is possible. Before running such a plant, it is necessary to simulate and optimize the process feeding strategy. Current simulation models are either very detailed like the ADM 1, which leads to very long optimization runtimes or not accurate enough to handle the biogas production kinetics. Therefore this paper provides a new model of a biogas plant, which is easy to parametrize but also has the needed accuracy for the output prediction. It is based on the control system approach of system identification and validated with laboratory results of a real biogas production testing facility.

  7. A hybrid approach to modeling and control of vehicle height for electronically controlled air suspension

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoqiang; Cai, Yingfeng; Wang, Shaohua; Liu, Yanling; Chen, Long

    2016-01-01

    The control problems associated with vehicle height adjustment of electronically controlled air suspension (ECAS) still pose theoretical challenges for researchers, which manifest themselves in the publications on this subject over the last years. This paper deals with modeling and control of a vehicle height adjustment system for ECAS, which is an example of a hybrid dynamical system due to the coexistence and coupling of continuous variables and discrete events. A mixed logical dynamical (MLD) modeling approach is chosen for capturing enough details of the vehicle height adjustment process. The hybrid dynamic model is constructed on the basis of some assumptions and piecewise linear approximation for components nonlinearities. Then, the on-off statuses of solenoid valves and the piecewise approximation process are described by propositional logic, and the hybrid system is transformed into the set of linear mixed-integer equalities and inequalities, denoted as MLD model, automatically by HYSDEL. Using this model, a hybrid model predictive controller (HMPC) is tuned based on online mixed-integer quadratic optimization (MIQP). Two different scenarios are considered in the simulation, whose results verify the height adjustment effectiveness of the proposed approach. Explicit solutions of the controller are computed to control the vehicle height adjustment system in realtime using an offline multi-parametric programming technology (MPT), thus convert the controller into an equivalent explicit piecewise affine form. Finally, bench experiments for vehicle height lifting, holding and lowering procedures are conducted, which demonstrate that the HMPC can adjust the vehicle height by controlling the on-off statuses of solenoid valves directly. This research proposes a new modeling and control method for vehicle height adjustment of ECAS, which leads to a closed-loop system with favorable dynamical properties.

  8. A fuzzy behaviorist approach to sensor-based robot control

    SciTech Connect

    Pin, F.G.

    1996-05-01

    Sensor-based operation of autonomous robots in unstructured and/or outdoor environments has revealed to be an extremely challenging problem, mainly because of the difficulties encountered when attempting to represent the many uncertainties which are always present in the real world. These uncertainties are primarily due to sensor imprecisions and unpredictability of the environment, i.e., lack of full knowledge of the environment characteristics and dynamics. An approach. which we have named the {open_quotes}Fuzzy Behaviorist Approach{close_quotes} (FBA) is proposed in an attempt to remedy some of these difficulties. This approach is based on the representation of the system`s uncertainties using Fuzzy Set Theory-based approximations and on the representation of the reasoning and control schemes as sets of elemental behaviors. Using the FBA, a formalism for rule base development and an automated generator of fuzzy rules have been developed. This automated system can automatically construct the set of membership functions corresponding to fuzzy behaviors. Once these have been expressed in qualitative terms by the user. The system also checks for completeness of the rule base and for non-redundancy of the rules (which has traditionally been a major hurdle in rule base development). Two major conceptual features, the suppression and inhibition mechanisms which allow to express a dominance between behaviors are discussed in detail. Some experimental results obtained with the automated fuzzy, rule generator applied to the domain of sensor-based navigation in aprion unknown environments. using one of our autonomous test-bed robots as well as a real car in outdoor environments, are then reviewed and discussed to illustrate the feasibility of large-scale automatic fuzzy rule generation using the {open_quotes}Fuzzy Behaviorist{close_quotes} concepts.

  9. LaRC controls activity for LSST

    NASA Technical Reports Server (NTRS)

    Montgomery, R. C.

    1980-01-01

    Math models were developed for various types of large flexible structures. These models were used to study the uncontrolled dynamic characteristics of the structures in orbit and to devise control concepts in order to control their orientation and geometrical shape. Reduced order decoupled control of the 100 meter long free free beam were studied. The inplane orientation and shape of the beam was controlled in a decoupled manner with as few actuators as possible. Using two controllers, near each end of the beam, to produce a 0.01 radian pitch change, perfect decoupled control was achieved for the rigid body pitch theta mode and the first flexible mode A sub 1.

  10. Controlled Release of Biologically Active Silver from Nanosilver Surfaces

    PubMed Central

    Liu, Jingyu; Sonshine, David A.; Shervani, Saira; Hurt, Robert H.

    2010-01-01

    Major pathways in the antibacterial activity and eukaryotic toxicity of nano-silver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nano-silver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nano-silver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nano-silver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nano-silver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over four orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by pre-oxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and release inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through bacterial inhibition zone assay carried out on selected formulations of controlled release nano-silver. PMID:20968290

  11. Anticancer Activity of Estradiol Derivatives: A Quantitative Structure--Activity Relationship Approach

    NASA Astrophysics Data System (ADS)

    Muranaka, Ken

    2001-10-01

    Commercial packages to implement modern QSAR (quantitative structure-activity relationship) techniques are highly priced; however, the essence of QSAR can be taught without them. Microsoft Excel was used to analyze published data on anticancer activities of estradiol analogs by a QSAR approach. The resulting QSAR equations highly correlate the structural features and physicochemical properties of the analogs with the observed biological activities by multiple linear regression.

  12. Development of Postural Control in Healthy Children: A Functional Approach

    PubMed Central

    Assaiante, Christine; Mallau, Sophie; Viel, Sébastien; Jover, Marianne; Schmitz, Christina

    2005-01-01

    From a set of experimental studies showing how intersegmental coordination develops during childhood in various posturokinetic tasks, we have established a repertoire of equilibrium strategies in the course of ontogenesis. The experimental data demonstrate that the first reference frame used for the organization of balance control during locomotion is the pelvis, especially in young children. Head stabilization during posturokinetic activities, particularly locomotion, constitutes a complex motor skill requiring a long time to develop during childhood. When studying the emergence of postural strategies, it is essential to distinguish between results that can be explained by biomechanical reasons strictly and those reflecting the maturation of the central nervous system (CNS). To address this problem, we have studied our young subjects in situations requiring various types of adaptation. The studies dealing with adaptation of postural strategies aimed at testing short and long-term adaptation capacity of the CNS during imposed transient external biomechanical constraints in healthy children, and during chronic internal constraints in children with skeletal pathologies. In addition to maintenance of balance, another function of posture is to ensure the orientation of a body segment. It appears that the control of orientation and the control of balance both require the trunk as an initial reference frame involving a development from egocentric to exocentric postural control. It is concluded that the first step for children consists in building a repertoire of postural strategies, and the second step consists in learning to select the most appropriate postural strategy, depending on the ability to anticipate the consequence of the movement in order to maintain balance control and the efficiency of the task. PMID:16097479

  13. Control of Thermo-Acoustics Instabilities: The Multi-Scale Extended Kalman Approach

    NASA Technical Reports Server (NTRS)

    Le, Dzu K.; DeLaat, John C.; Chang, Clarence T.

    2003-01-01

    "Multi-Scale Extended Kalman" (MSEK) is a novel model-based control approach recently found to be effective for suppressing combustion instabilities in gas turbines. A control law formulated in this approach for fuel modulation demonstrated steady suppression of a high-frequency combustion instability (less than 500Hz) in a liquid-fuel combustion test rig under engine-realistic conditions. To make-up for severe transport-delays on control effect, the MSEK controller combines a wavelet -like Multi-Scale analysis and an Extended Kalman Observer to predict the thermo-acoustic states of combustion pressure perturbations. The commanded fuel modulation is composed of a damper action based on the predicted states, and a tones suppression action based on the Multi-Scale estimation of thermal excitations and other transient disturbances. The controller performs automatic adjustments of the gain and phase of these actions to minimize the Time-Scale Averaged Variances of the pressures inside the combustion zone and upstream of the injector. The successful demonstration of Active Combustion Control with this MSEK controller completed an important NASA milestone for the current research in advanced combustion technologies.

  14. Application of Semi Active Control Techniques to the Damping Suppression Problem of Solar Sail Booms

    NASA Technical Reports Server (NTRS)

    Adetona, O.; Keel, L. H.; Whorton, M. S.

    2007-01-01

    Solar sails provide a propellant free form for space propulsion. These are large flat surfaces that generate thrust when they are impacted by light. When attached to a space vehicle, the thrust generated can propel the space vehicle to great distances at significant speeds. For optimal performance the sail must be kept from excessive vibration. Active control techniques can provide the best performance. However, they require an external power-source that may create significant parasitic mass to the solar sail. However, solar sails require low mass for optimal performance. Secondly, active control techniques typically require a good system model to ensure stability and performance. However, the accuracy of solar sail models validated on earth for a space environment is questionable. An alternative approach is passive vibration techniques. These do not require an external power supply, and do not destabilize the system. A third alternative is referred to as semi-active control. This approach tries to get the best of both active and passive control, while avoiding their pitfalls. In semi-active control, an active control law is designed for the system, and passive control techniques are used to implement it. As a result, no external power supply is needed so the system is not destabilize-able. Though it typically underperforms active control techniques, it has been shown to out-perform passive control approaches and can be unobtrusively installed on a solar sail boom. Motivated by this, the objective of this research is to study the suitability of a Piezoelectric (PZT) patch actuator/sensor based semi-active control system for the vibration suppression problem of solar sail booms. Accordingly, we develop a suitable mathematical and computer model for such studies and demonstrate the capabilities of the proposed approach with computer simulations.

  15. A transgenic approach for controlling Lygus in cotton.

    PubMed

    Gowda, Anilkumar; Rydel, Timothy J; Wollacott, Andrew M; Brown, Robert S; Akbar, Waseem; Clark, Thomas L; Flasinski, Stanislaw; Nageotte, Jeffrey R; Read, Andrew C; Shi, Xiaohong; Werner, Brent J; Pleau, Michael J; Baum, James A

    2016-07-18

    Lygus species of plant-feeding insects have emerged as economically important pests of cotton in the United States. These species are not controlled by commercial Bacillus thuringiensis (Bt) cotton varieties resulting in economic losses and increased application of insecticide. Previously, a Bt crystal protein (Cry51Aa2) was reported with insecticidal activity against Lygus spp. However, transgenic cotton plants expressing this protein did not exhibit effective protection from Lygus feeding damage. Here we employ various optimization strategies, informed in part by protein crystallography and modelling, to identify limited amino-acid substitutions in Cry51Aa2 that increase insecticidal activity towards Lygus spp. by >200-fold. Transgenic cotton expressing the variant protein, Cry51Aa2.834_16, reduce populations of Lygus spp. up to 30-fold in whole-plant caged field trials. One transgenic event, designated MON88702, has been selected for further development of cotton varieties that could potentially reduce or eliminate insecticide application for control of Lygus and the associated environmental impacts.

  16. A transgenic approach for controlling Lygus in cotton

    PubMed Central

    Gowda, Anilkumar; Rydel, Timothy J.; Wollacott, Andrew M.; Brown, Robert S.; Akbar, Waseem; Clark, Thomas L.; Flasinski, Stanislaw; Nageotte, Jeffrey R.; Read, Andrew C.; Shi, Xiaohong; Werner, Brent J.; Pleau, Michael J.; Baum, James A.

    2016-01-01

    Lygus species of plant-feeding insects have emerged as economically important pests of cotton in the United States. These species are not controlled by commercial Bacillus thuringiensis (Bt) cotton varieties resulting in economic losses and increased application of insecticide. Previously, a Bt crystal protein (Cry51Aa2) was reported with insecticidal activity against Lygus spp. However, transgenic cotton plants expressing this protein did not exhibit effective protection from Lygus feeding damage. Here we employ various optimization strategies, informed in part by protein crystallography and modelling, to identify limited amino-acid substitutions in Cry51Aa2 that increase insecticidal activity towards Lygus spp. by >200-fold. Transgenic cotton expressing the variant protein, Cry51Aa2.834_16, reduce populations of Lygus spp. up to 30-fold in whole-plant caged field trials. One transgenic event, designated MON88702, has been selected for further development of cotton varieties that could potentially reduce or eliminate insecticide application for control of Lygus and the associated environmental impacts. PMID:27426014

  17. Active controllers and the time duration to learn a task

    NASA Technical Reports Server (NTRS)

    Repperger, D. W.; Goodyear, C.

    1986-01-01

    An active controller was used to help train naive subjects involved in a compensatory tracking task. The controller is called active in this context because it moves the subject's hand in a direction to improve tracking. It is of interest here to question whether the active controller helps the subject to learn a task more rapidly than the passive controller. Six subjects, inexperienced to compensatory tracking, were run to asymptote root mean square error tracking levels with an active controller or a passive controller. The time required to learn the task was defined several different ways. The results of the different measures of learning were examined across pools of subjects and across controllers using statistical tests. The comparison between the active controller and the passive controller as to their ability to accelerate the learning process as well as reduce levels of asymptotic tracking error is reported here.

  18. Ultrasensitive Negative Feedback Control: A Natural Approach for the Design of Synthetic Controllers

    PubMed Central

    Montefusco, Francesco; Akman, Ozgur E.; Soyer, Orkun S.; Bates, Declan G.

    2016-01-01

    Many of the most important potential applications of Synthetic Biology will require the ability to design and implement high performance feedback control systems that can accurately regulate the dynamics of multiple molecular species within the cell. Here, we argue that the use of design strategies based on combining ultrasensitive response dynamics with negative feedback represents a natural approach to this problem that fully exploits the strongly nonlinear nature of cellular information processing. We propose that such feedback mechanisms can explain the adaptive responses observed in one of the most widely studied biomolecular feedback systems—the yeast osmoregulatory response network. Based on our analysis of such system, we identify strong links with a well-known branch of mathematical systems theory from the field of Control Engineering, known as Sliding Mode Control. These insights allow us to develop design guidelines that can inform the construction of feedback controllers for synthetic biological systems. PMID:27537373

  19. Active Control of Complex Physical Systems: An Overview

    DTIC Science & Technology

    1992-09-01

    release; distribution is unlimited. 13. ABSTRACT (Maxtmum 200 words) Active control of complex systems imposes unique requirements for physical models and...months after the meeting, SPrinte In USA. Acceslon For NTIS CRA&W DTIC TAB Unlannounced ] Active Control of Complex Physical Systems Justificatton An...control strategies. Physical models This work on the active control of which are adequate to predict the influence of specific physical systems has been

  20. AN APPROACH TO SAFETY DESIGN BASIS DOCUMENTATION CHANGE CONTROL

    SciTech Connect

    RYAN GW

    2008-05-15

    This paper describes a safety design basis documentation change control process. The process identifies elements that can be used to manage the project/facility configuration during design evolution through the Initiation, Definition, and Execution project phases. The project phases addressed by the process are defined in US Department of Energy (DOE) Order (O) 413.3A, Program and Project Management for the Acquisition of Capital Assets, in support of DOE project Critical Decisions (CD). This approach has been developed for application to two Hanford Site projects in their early CD phases and is considered to be a key element of safety and design integration. As described in the work that has been performed, the purpose of change control is to maintain consistency among design requirements, the physical configuration, related facility documentation, and the nuclear safety basis during the evolution of the design. The process developed (1) ensures an appropriate level of rigor is applied at each project phase and (2) is considered to implement the requirements and guidance provided in DOE-STD-1189-2008, Integration of Safety into the Design Process. Presentation of this work is expected to benefit others in the DOE Complex that may be implementing DOE-STD-1189-2008 or managing nuclear safety documentation in support of projects in-process.

  1. An enhanced nonlinear damping approach accounting for system constraints in active mass dampers

    NASA Astrophysics Data System (ADS)

    Venanzi, Ilaria; Ierimonti, Laura; Ubertini, Filippo

    2015-11-01

    Active mass dampers are a viable solution for mitigating wind-induced vibrations in high-rise buildings and improve occupants' comfort. Such devices suffer particularly when they reach force saturation of the actuators and maximum extension of their stroke, which may occur in case of severe loading conditions (e.g. wind gust and earthquake). Exceeding actuators' physical limits can impair the control performance of the system or even lead to devices damage, with consequent need for repair or substitution of part of the control system. Controllers for active mass dampers should account for their technological limits. Prior work of the authors was devoted to stroke issues and led to the definition of a nonlinear damping approach, very easy to implement in practice. It consisted of a modified skyhook algorithm complemented with a nonlinear braking force to reverse the direction of the mass before reaching the stroke limit. This paper presents an enhanced version of this approach, also accounting for force saturation of the actuator and keeping the simplicity of implementation. This is achieved by modulating the control force by a nonlinear smooth function depending on the ratio between actuator's force and saturation limit. Results of a numerical investigation show that the proposed approach provides similar results to the method of the State Dependent Riccati Equation, a well-established technique for designing optimal controllers for constrained systems, yet very difficult to apply in practice.

  2. Quasi-modal vibration control by means of active control bearings

    NASA Technical Reports Server (NTRS)

    Nonami, K.; Fleming, D. P.

    1986-01-01

    This paper investigates a design method of an active control bearing system with only velocity feedback. The study provides a new quasi-modal control method for a control system design of an active control bearing system in which feedback coefficients are determined on the basis of a modal analysis. Although the number of sensors and actuators is small, this quasi-modal control method produces a control effect close to an ideal modal control.

  3. An active, collaborative approach to learning skills in flow cytometry.

    PubMed

    Fuller, Kathryn; Linden, Matthew D; Lee-Pullen, Tracey; Fragall, Clayton; Erber, Wendy N; Röhrig, Kimberley J

    2016-06-01

    Advances in science education research have the potential to improve the way students learn to perform scientific interpretations and understand science concepts. We developed active, collaborative activities to teach skills in manipulating flow cytometry data using FlowJo software. Undergraduate students were given compensated clinical flow cytometry listmode output (FCS) files and asked to design a gating strategy to diagnose patients with different hematological malignancies on the basis of their immunophenotype. A separate cohort of research trainees was given uncompensated data files on which they performed their own compensation, calculated the antibody staining index, designed a sequential gating strategy, and quantified rare immune cell subsets. Student engagement, confidence, and perceptions of flow cytometry were assessed using a survey. Competency against the learning outcomes was assessed by asking students to undertake tasks that required understanding of flow cytometry dot plot data and gating sequences. The active, collaborative approach allowed students to achieve learning outcomes not previously possible with traditional teaching formats, for example, having students design their own gating strategy, without forgoing essential outcomes such as the interpretation of dot plots. In undergraduate students, favorable perceptions of flow cytometry as a field and as a potential career choice were correlated with student confidence but not the ability to perform flow cytometry data analysis. We demonstrate that this new pedagogical approach to teaching flow cytometry is beneficial for student understanding and interpretation of complex concepts. It should be considered as a useful new method for incorporating complex data analysis tasks such as flow cytometry into curricula.

  4. Decentralized harmonic control of sound radiation and transmission by a plate using a virtual impedance approach.

    PubMed

    Quaegebeur, Nicolas; Micheau, Philippe; Berry, Alain

    2009-05-01

    The problem under study in this article is the active control of sound transmission and radiation of a panel under a periodic excitation. The control strategy investigated uses independent control loops between an individual polyvinylidene fluoride (PVDF) sensor and an individual lead zirconate titanate (PZT) actuator. The specific approach employed here uses the concept of virtual impedance. The aim is to determine for each frequency the optimal impedance between each PVDF sensor and the corresponding PZT actuator in order to reduce the sound power radiated by the plate. Theoretical predictions are compared to measurements of the sound radiated and transmission loss of a panel mounted with eight PZT-PVDF units. Reductions of up to 20 dB of the acoustic power can be achieved around mechanical resonances of the system, while the control strategy has little effect for off-resonance excitations.

  5. Improved training of neural networks for the nonlinear active control of sound and vibration.

    PubMed

    Bouchard, M; Paillard, B; Le Dinh, C T

    1999-01-01

    Active control of sound and vibration has been the subject of a lot of research in recent years, and examples of applications are now numerous. However, few practical implementations of nonlinear active controllers have been realized. Nonlinear active controllers may be required in cases where the actuators used in active control systems exhibit nonlinear characteristics, or in cases when the structure to be controlled exhibits a nonlinear behavior. A multilayer perceptron neural-network based control structure was previously introduced as a nonlinear active controller, with a training algorithm based on an extended backpropagation scheme. This paper introduces new heuristical training algorithms for the same neural-network control structure. The objective is to develop new algorithms with faster convergence speed (by using nonlinear recursive-least-squares algorithms) and/or lower computational loads (by using an alternative approach to compute the instantaneous gradient of the cost function). Experimental results of active sound control using a nonlinear actuator with linear and nonlinear controllers are presented. The results show that some of the new algorithms can greatly improve the learning rate of the neural-network control structure, and that for the considered experimental setup a neural-network controller can outperform linear controllers.

  6. Active Brownian particles at interfaces: An effective equilibrium approach

    NASA Astrophysics Data System (ADS)

    Wittmann, René; Brader, Joseph M.

    2016-06-01

    A simple theoretical approach is used to investigate active colloids at the free interface and near repulsive substrates. We employ dynamical density functional theory to determine the steady-state density profiles in an effective equilibrium system (Farage T. F. F. et al., Phys. Rev. E, 91 (2015) 042310). In addition to the known accumulation at surfaces, we predict wetting and drying transitions at a flat repulsive wall and capillary condensation and evaporation in a slit pore. These new phenomena are closely related to the motility-induced phase separation (MIPS) in the bulk.

  7. Legacy activities as interventions approaching the end of life.

    PubMed

    Allen, Rebecca S; Hilgeman, Michelle M; Ege, Margaret A; Shuster, John L; Burgio, Louis D

    2008-09-01

    We examined the efficacy of an innovative family-based intervention designed to decrease caregiving stress and increase family communication among individuals with chronic, life-limiting illnesses and their family caregivers in a randomized, contact control group design. The intervention group received three home visits in which the interventionist actively worked with the family to construct a personal Legacy, usually a scrapbook with photographs or audiotaped stories. Control group families received three supportive telephone calls. Of the 42 families that entered the project, 31 families completed follow-up assessments within 9 to 10 weeks (14 control; 17 intervention; 72% African American) for a retention rate of 74%. Intervention caregivers showed reduced caregiving stress in comparison with control group caregivers, who showed increases in stress. Intervention patients reported decreased breathing difficulty and increased religious meaning. Caregivers and patients reported greater social interaction on the part of the patient. All participants in the intervention group initiated a Legacy activity and reported that Legacy improved family communication. Legacy interventions hold promise and are simple to implement.

  8. Legacy Activities as Interventions Approaching the End of Life

    PubMed Central

    Hilgeman, Michelle M.; Ege, Margaret A.; Shuster, John L.; Burgio, Louis D.

    2008-01-01

    Abstract We examined the efficacy of an innovative family-based intervention designed to decrease caregiving stress and increase family communication among individuals with chronic, life-limiting illnesses and their family caregivers in a randomized, contact control group design. The intervention group received three home visits in which the interventionist actively worked with the family to construct a personal Legacy, usually a scrap-book with photographs or audiotaped stories. Control group families received three supportive telephone calls. Of the 42 families that entered the project, 31 families completed follow-up assessments within 9 to 10 weeks (14 control; 17 intervention; 72% African American) for a retention rate of 74%. Intervention caregivers showed reduced caregiving stress in comparison with control group caregivers, who showed increases in stress. Intervention patients reported decreased breathing difficulty and increased religious meaning. Caregivers and patients reported greater social interaction on the part of the patient. All participants in the intervention group initiated a Legacy activity and reported that Legacy improved family communication. Legacy interventions hold promise and are simple to implement. PMID:18788966

  9. 40 CFR 194.41 - Active institutional controls.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... controls and their effectiveness in terms of preventing or reducing radionuclide releases shall be... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Active institutional controls. 194.41... Assurance Requirements § 194.41 Active institutional controls. (a) Any compliance application shall...

  10. Active parallel redundancy for electronic integrator-type control circuits

    NASA Technical Reports Server (NTRS)

    Peterson, R. A.

    1971-01-01

    Circuit extends concept of redundant feedback control from type-0 to type-1 control systems. Inactive channels are slaves to the active channel, if latter fails, it is rejected and slave channel is activated. High reliability and elimination of single-component catastrophic failure are important in closed-loop control systems.

  11. Detectability of active triangulation range finder: a solar irradiance approach.

    PubMed

    Liu, Huizhe; Gao, Jason; Bui, Viet Phuong; Liu, Zhengtong; Lee, Kenneth Eng Kian; Peh, Li-Shiuan; Png, Ching Eng

    2016-06-27

    Active triangulation range finders are widely used in a variety of applications such as robotics and assistive technologies. The power of the laser source should be carefully selected in order to satisfy detectability and still remain eye-safe. In this paper, we present a systematic approach to assess the detectability of an active triangulation range finder in an outdoor environment. For the first time, we accurately quantify the background noise of a laser system due to solar irradiance by coupling the Perez all-weather sky model and ray tracing techniques. The model is validated with measurements with a modeling error of less than 14.0%. Being highly generic and sufficiently flexible, the proposed model serves as a guide to define a laser system for any geographical location and microclimate.

  12. Engineering Approaches Toward Deconstructing and Controlling the Stem Cell Environment

    PubMed Central

    Edalat, Faramarz; Bae, Hojae; Manoucheri, Sam; Cha, Jae Min; Khademhosseini, Ali

    2012-01-01

    Stem cell-based therapeutics have become a vital component in tissue engineering and regenerative medicine. The microenvironment within which stem cells reside, i.e. the niche, plays a crucial role in regulating stem cell self-renewal and differentiation. However, current biological techniques lack the means to recapitulate the complexity of this microenvironment. Nano- and microengineered materials offer innovative methods to: (1) deconstruct the stem cell niche to understand the effects of individual elements; (2) construct complex tissue-like structures resembling the niche to better predict and control cellular processes; and (3) transplant stem cells or activate endogenous stem cell populations for regeneration of aged or diseased tissues. Here, we highlight some of the latest advances in this field and discuss future applications and directions of the use of nano- and microtechnologies for stem cell engineering. PMID:22101755

  13. Extraversion and behavioral activation: integrating the components of approach.

    PubMed

    Quilty, Lena C; DeYoung, Colin G; Oakman, Jonathan M; Bagby, R Michael

    2014-01-01

    This investigation evaluates the structure and correlates of lower order traits related to approach, specifically, facets of extraversion and behavioral activation system (BAS) sensitivity. A 3-factor structure of approach was derived in community and clinical samples: assertiveness, enthusiasm, and sensation seeking. All factors were positively associated with Openness/Intellect scores. Enthusiasm and assertiveness were both negatively associated with Neuroticism scores, but were distinguished by associations with Agreeableness and Conscientiousness. Sensation seeking was negatively associated with Conscientiousness scores. The 3 factors demonstrated a unique profile of association with components of impulsivity. Enthusiasm and assertiveness were negatively related to psychopathological symptoms, whereas sensation seeking was largely independent of psychopathology. Results suggest that approach is associated with 3 subfactors, which differ in their pattern or magnitude of associations with other variables, thus underscoring the importance of distinguishing among them. Further, results support the construct validity of the Assertiveness and Enthusiasm aspect scales of the Big Five Aspect Scales to assess traits at this level of the personality hierarchy.

  14. Data Assimilation Approach for Forecast of Solar Activity Cycles

    NASA Astrophysics Data System (ADS)

    Kitiashvili, Irina N.

    2016-11-01

    Numerous attempts to predict future solar cycles are mostly based on empirical relations derived from observations of previous cycles, and they yield a wide range of predicted strengths and durations of the cycles. Results obtained with current dynamo models also deviate strongly from each other, thus raising questions about criteria to quantify the reliability of such predictions. The primary difficulties in modeling future solar activity are shortcomings of both the dynamo models and observations that do not allow us to determine the current and past states of the global solar magnetic structure and its dynamics. Data assimilation is a relatively new approach to develop physics-based predictions and estimate their uncertainties in situations where the physical properties of a system are not well-known. This paper presents an application of the ensemble Kalman filter method for modeling and prediction of solar cycles through use of a low-order nonlinear dynamo model that includes the essential physics and can describe general properties of the sunspot cycles. Despite the simplicity of this model, the data assimilation approach provides reasonable estimates for the strengths of future solar cycles. In particular, the prediction of Cycle 24 calculated and published in 2008 is so far holding up quite well. In this paper, I will present my first attempt to predict Cycle 25 using the data assimilation approach, and discuss the uncertainties of that prediction.

  15. Active traffic management on road networks: a macroscopic approach.

    PubMed

    Kurzhanskiy, Alex A; Varaiya, Pravin

    2010-10-13

    Active traffic management (ATM) is the ability to dynamically manage recurrent and non-recurrent congestion based on prevailing traffic conditions in order to maximize the effectiveness and efficiency of road networks. It is a continuous process of (i) obtaining and analysing traffic measurement data, (ii) operations planning, i.e. simulating various scenarios and control strategies, (iii) implementing the most promising control strategies in the field, and (iv) maintaining a real-time decision support system that filters current traffic measurements to predict the traffic state in the near future, and to suggest the best available control strategy for the predicted situation. ATM relies on a fast and trusted traffic simulator for the rapid quantitative assessment of a large number of control strategies for the road network under various scenarios, in a matter of minutes. The open-source macrosimulation tool Aurora ROAD NETWORK MODELER is a good candidate for this purpose. The paper describes the underlying dynamical traffic model and what it takes to prepare the model for simulation; covers the traffic performance measures and evaluation of scenarios as part of operations planning; introduces the framework within which the control strategies are modelled and evaluated; and presents the algorithm for real-time traffic state estimation and short-term prediction.

  16. A simple assay for measuring catalase activity: a visual approach.

    PubMed

    Iwase, Tadayuki; Tajima, Akiko; Sugimoto, Shinya; Okuda, Ken-ichi; Hironaka, Ippei; Kamata, Yuko; Takada, Koji; Mizunoe, Yoshimitsu

    2013-10-30

    In this study, an assay that combines the ease and simplicity of the qualitative approach for measuring catalase activity was developed. The assay reagents comprised only hydrogen peroxide and Triton X-100. The enzyme-generated oxygen bubbles trapped by Triton X-100 were visualized as foam, whose height was estimated. A calibration plot using the defined unit of catalase activity yielded the best linear fit over a range of 20-300 units (U) (y = 0.3794x - 2.0909, r(2) = 0.993). The assay precision and reproducibility at 100 U were 4.6% and 4.8%, respectively. The applicability of the assay for measuring the catalase activity of various samples was assessed using laboratory strains of Escherichia coli, catalase-deficient isogenic mutants, clinically isolated Shiga toxin-producing E. coli, and human cells. The assay generated reproducible results. In conclusion, this new assay can be used to measure the catalase activity of bacterial isolates and human cells.

  17. Electromechanical simulation and testing of actively controlled rotordynamic systems with piezoelectric actuators

    NASA Technical Reports Server (NTRS)

    Lin, Reng Rong; Palazzolo, A. B.; Kascak, A. F.; Montague, G. T.

    1991-01-01

    A method is presented for simulating the coupled 'electromechanical' system to predict rotordynamic stability and unbalance response along with control system stability. The piezoelectric actuators and their amplifiers are represented as equivalent linear electrical circuits. The electromechanical system modeling approach is utilized to correlate test results from a double overhung rotor rig. The test results also show the effectiveness of the control system for suppressing the unbalance response of two modes using active stiffness and active damping.

  18. Cometary activity and nucleus modelling: a new approach

    NASA Astrophysics Data System (ADS)

    Möhlmann, D.

    1996-06-01

    The phenomena of comet splittings with an average frequency of about one splitting per 100 years and comet (Chen and Jewitt, Icarus108, 265-271, 1994), and the restriction of cometary activity to well-defined small areas at the almost passive and mantle covered surface (Keller et al., ESA SP-250, Vol. II, pp. 363-364, 1986) are at present driving challenges to models of structure and evolution of comet nuclei. Extending the presently discussed models by incorporating lateral subsurface transport of sublimed volatiles, there appears the possibility that the places of sublimation are different from those of activity (the so-called active areas). Then, there is no necessity to distinguish between different surface properties at active and passive areas, assuming, e.g. an uncovered icy surface at active areas. Active areas are simply the very local "source sites" where the accumulated subsurface flows from distant regions reach the surface. The pressure driven subsurface flows of volatiles may not only leave the comet at its surface, they may penetrate via cracks, etc. also deeply into the nucleus. There they can cause a further growth of cracks and also new cracks. This can be a cause for the observed regular splittings. Furthermore, actual models (Kührt and Keller, Icarus109, 121-132, 1994; Skorov and Rickman, Planet. Space Sci.43, 1587-1594, 1995) of the gas transport through porous comet surface crusts can be interpreted as to give first indications for thermodynamical parameters in heat conducting and porous cometary crusts which are appropriate for 1 AU conditions to permit the temporary existence of a layer with fluid subsurface water within these crusts. This exciting result of the possible temporary existence of subsurface warm water in comets which approach the Sun within about 1 AU makes a cometary subsurface chemistry much more efficient than expected hitherto.

  19. Avoid, Control, Succumb, or Balance: Engineering Students' Approaches to a Wicked Sustainability Problem

    NASA Astrophysics Data System (ADS)

    Lönngren, Johanna; Ingerman, Åke; Svanström, Magdalena

    2016-07-01

    Wicked sustainability problems (WSPs) are an important and particularly challenging type of problem. Science and engineering education can play an important role in preparing students to deal with such problems, but current educational practice may not adequately prepare students to do so. We address this gap by providing insights related to students' abilities to address WSPs. Specifically, we aim to (I) describe key constituents of engineering students' approaches to a WSP, (II) evaluate these approaches in relation to the normative context of education for sustainable development (ESD), and (III) identify relevant aspects of learning related to WSPs. Aim I is addressed through a phenomenographic study, while aims II and III are addressed by relating the results to research literature about human problem solving, sustainable development, and ESD. We describe four qualitatively different ways of approaching a specific WSP, as the outcome of the phenomenographic study: A. Simplify and avoid, B. Divide and control, C. Isolate and succumb, and D. Integrate and balance. We identify approach D as the most appropriate approach in the context of ESD, while A and C are not. On this basis, we identify three learning objectives related to students' abilities to address WSPs: learn to use a fully integrative approach, distinguish WSPs from tame and well-structured problems, and understand and consider the normative context of SD. Finally, we provide recommendations for how these learning objectives can be used to guide the design of science and engineering educational activities.

  20. Active Combustion Control for Aircraft Gas Turbine Engines

    NASA Technical Reports Server (NTRS)

    DeLaat, John C.; Breisacher, Kevin J.; Saus, Joseph R.; Paxson, Daniel E.

    2000-01-01

    Lean-burning combustors are susceptible to combustion instabilities. Additionally, due to non-uniformities in the fuel-air mixing and in the combustion process, there typically exist hot areas in the combustor exit plane. These hot areas limit the operating temperature at the turbine inlet and thus constrain performance and efficiency. Finally, it is necessary to optimize the fuel-air ratio and flame temperature throughout the combustor to minimize the production of pollutants. In recent years, there has been considerable activity addressing Active Combustion Control. NASA Glenn Research Center's Active Combustion Control Technology effort aims to demonstrate active control in a realistic environment relevant to aircraft engines. Analysis and experiments are tied to aircraft gas turbine combustors. Considerable progress has been shown in demonstrating technologies for Combustion Instability Control, Pattern Factor Control, and Emissions Minimizing Control. Future plans are to advance the maturity of active combustion control technology to eventual demonstration in an engine environment.

  1. Magnetic microswimmers: Controlling particle approach through magnetic and hydrodynamic interaction

    NASA Astrophysics Data System (ADS)

    Meshkati, Farshad; Cheang, U. Kei; Kim, Minjun; Fu, Henry

    2015-11-01

    We investigate magnetic microswimmers actuated by a rotating magnetic field that may be useful for drug delivery, micro-surgery, or diagnostics in human body. For modular swimmers, assembly and disassembly requires understanding the interactions between the swimmer and other modules in the fluid. Here, we discuss possible mechanisms for a frequency-dependent attraction/repulsion between a three-bead, achiral swimmer and other magnetic particles, which represent modular assembly elements. We first investigate the hydrodynamic interaction between a swimmer and nearby particle by studying the Lagrangian trajectories in the vicinity of the swimmer. Then we show that the magnetic forces can be attractive or repulsive depending on the spatial arrangement of the swimmer and particle, with a magnitude that decreases with increasing frequency. Combining magnetic and hydrodynamic effects allows us to understand the overall behavior of magnetic particles near the swimmer. Interestingly, we find that the frequency of rotation can be used to control when the particle can closely approach the swimmer, with potential application to assembly.

  2. Combinatorial approach for fabrication of coatings to control bacterial adhesion.

    PubMed

    Pedron, S; Peinado, C; Catalina, F; Bosch, P; Anseth, K S; Abrusci, C

    2012-01-01

    Due to the high importance of bacterial infections in medical devices there is an increasing interest in the design of anti-fouling coatings. The application of substrates with controlled chemical gradients to prevent microbial adhesion is presented. We describe here the co-polymerization of poly(ethylene glycol) dimethacrylate with a hyperbranched multimethacrylate (H30MA) using a chemical gradient generator; and the resulting films were characterized with respect to their ability to serve as coating for biomedical devices. The photo-polymerized materials present special surface properties due to the hyperbranched structure of H30MA and phase separation at specific concentrations in the PEGDM matrix. This approach affords the investigation of cell response to a large range of different chemistries on a single sample. Two bacterial strains commonly associated with surgical site infections, Escherichia coli and Pseudomonas aeruginosa, have been cultured on these substrates to study their attachment behaviour. These gradient-coated samples demonstrate less bacterial adhesion at higher concentrations of H30MA, and the adhesion is substantially affected by the extent of surface phase segregation.

  3. Measurement approaches to support future warhead arms control transparency

    SciTech Connect

    Olinger, C.T.; Frankle, C.M.; Johnson, M.W.; Poths, J.

    1998-12-31

    Transparency on warhead stockpiles, warhead dismantlement, and fissile material stockpiles in nuclear weapons states will become increasingly important in the move beyond START II toward lower quantities of warheads. Congressional support for further warhead reductions will likely depend on the degree of irreversibility, or in other words, the rapidity with which warhead inventories could be reconstituted. Whether irreversibility considerations can be satisfied will depend on monitoring dismantlement as well as constraining the available stockpile of fissile materials for possible refabrication into warheads. Measurement techniques designed to address the above problems will need to consider NPT Article 1 obligations as well as Russian and US classification regulations, which prohibit or restrict the transfer of nuclear warhead design information to other states. Classification considerations currently limit the potential completeness of future inspections of weapons materials. Many conventional international safeguards approaches are not currently viable for arms control applications because they would reveal weapons design information. The authors discuss a variety of technical measures that may help to improve transparence of warhead and fissile material stockpiles and may enable limited warhead dismantlement transparency.

  4. Actively controlled shaft seals for aerospace applications

    NASA Technical Reports Server (NTRS)

    Salant, Richard F.

    1991-01-01

    The main objective is to determine the feasibility of utilizing controllable mechanical seals for aerospace applications. A potential application was selected as a demonstration case: the buffer gas seal in a LOX (liquid oxygen) turbopump. Currently, floating ring seals are used in this application. Their replacement with controllable mechanical seals would result in substantially reduced leakage rates. This would reduce the required amount of stored buffer gas, and therefore increase the vehicle payload. For such an application, a suitable controllable mechanical seal was designed and analyzed.

  5. Acceleration-augmented LQG control of an active magnetic bearing

    NASA Astrophysics Data System (ADS)

    Feeley, Joseph J.

    A linear-quadratic-gaussian (LQG) regulator controller design for an acceleration-augmented active magnetic bearing (AMB) is outlined. Acceleration augmentation is a key feature in providing improved dynamic performance of the controller. The optimal control formulation provides a convenient method of trading-off fast transient response and force attenuation as control objectives.

  6. Acceleration-Augmented LQG Control of an Active Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    Feeley, Joseph J.

    1993-01-01

    A linear-quadratic-gaussian (LQG) regulator controller design for an acceleration-augmented active magnetic bearing (AMB) is outlined. Acceleration augmentation is a key feature in providing improved dynamic performance of the controller. The optimal control formulation provides a convenient method of trading-off fast transient response and force attenuation as control objectives.

  7. Internal models for interpreting neural population activity during sensorimotor control

    PubMed Central

    Golub, Matthew D; Yu, Byron M; Chase, Steven M

    2015-01-01

    To successfully guide limb movements, the brain takes in sensory information about the limb, internally tracks the state of the limb, and produces appropriate motor commands. It is widely believed that this process uses an internal model, which describes our prior beliefs about how the limb responds to motor commands. Here, we leveraged a brain-machine interface (BMI) paradigm in rhesus monkeys and novel statistical analyses of neural population activity to gain insight into moment-by-moment internal model computations. We discovered that a mismatch between subjects’ internal models and the actual BMI explains roughly 65% of movement errors, as well as long-standing deficiencies in BMI speed control. We then used the internal models to characterize how the neural population activity changes during BMI learning. More broadly, this work provides an approach for interpreting neural population activity in the context of how prior beliefs guide the transformation of sensory input to motor output. DOI: http://dx.doi.org/10.7554/eLife.10015.001 PMID:26646183

  8. Photo-active collagen systems with controlled triple helix architecture.

    PubMed

    Tronci, Giuseppe; Russell, Stephen J; Wood, David J

    2013-08-14

    The design of photo-active collagen systems is presented as a basis for establishing biomimetic materials with varied network architecture and programmable macroscopic properties. Following in-house isolation of type I collagen, reaction with vinyl-bearing compounds of varied backbone rigidity, i.e. 4-vinylbenzyl chloride (4VBC) and glycidyl methacrylate (GMA), was carried out. TNBS colorimetric assay, (1)H-NMR and ATR-FTIR confirmed covalent and tunable functionalization of collagen lysines. Depending on the type and extent of functionalization, controlled stability and thermal denaturation of triple helices were observed via circular dichroism (CD), whereby the hydrogen-bonding capability of introduced moieties was shown to play a major role. Full gel formation was observed following photo-activation of functionalized collagen solutions. The presence of a covalent network only slightly affected collagen triple helix conformation (as observed by WAXS and ATR-FTIR), confirming the structural organization of functionalized collagen precursors. Photo-activated hydrogels demonstrated an increased denaturation temperature (DSC) with respect to native collagen, suggesting that the formation of the covalent network successfully stabilized collagen triple helices. Moreover, biocompatibility and mechanical competence of obtained hydrogels were successfully demonstrated under physiologically-relevant conditions. These results demonstrate that this novel synthetic approach enabled the formation of biocompatible collagen systems with defined network architecture and programmable macroscopic properties, which can only partially be obtained with current synthetic methods.

  9. PARTICULATE EMISSION MEASUREMENTS FROM CONTROLLED CONSTRUCTION ACTIVITIES

    EPA Science Inventory

    The report summarized the results of field testing of the effectiveness of control measures for sources of fugitive particulate emissions found at construction sites. The effectiveness of watering temporary, unpaved travel surfaces on emissions of particulate matter with aerodyna...

  10. Active Control of pH in the Bioculture System Through Carbon Dioxide Control

    NASA Technical Reports Server (NTRS)

    Monhollon, Luke; Pletcher, David; Hauss, Jessica

    2016-01-01

    For successful cell research, the growth culture environment must be tightly controlled. Deviance from the optimal conditions will mask the desired variable being analyzed or lead to inconstancies in the results. In standard laboratories, technology and procedures are readily available for the reliable control of variables such as temperature, pH, nutrient loading, and dissolved gases. Due to the nature of spaceflight, and the inherent constraints to engineering designs, these same elements become a challenge to maintain at stable values by both automated and manual approaches. Launch mass, volume, and power usage create significant constraints to cell culture systems; nonetheless, innovative solutions for active environmental controls are available. The acidity of the growth media cannot be measured through standard probes due to the degradation of electrodes and reliance on indicators for chromatography. Alternatively, carbon dioxide sensors are capable of monitoring the pH by leveraging the relationship between the partial pressure of carbon dioxide and carbonic acid in solution across a membrane. In microgravity cell growth systems, the gas delivery system can be used to actively maintain the media at the proper acidity by maintaining a suitable gas mixture around permeable tubing. Through this method, launch mass and volume are significantly reduced through the efficient use of the limited gas supply in orbit.

  11. Active control of flexural vibrations in beams

    NASA Technical Reports Server (NTRS)

    Gerhold, Carl H.

    1987-01-01

    The feasibility of using piezoelectric actuators to control the flexural oscillations of large structures in space is investigated. Flexural oscillations are excited by impulsive loads. The vibratory response can degrade the pointing accuracy of cameras and antennae, and can cause high stresses at structural node points. Piezoelectric actuators have the advantage of exerting localized bending moments. In this way, vibration is controlled without exciting rigid body modes. The actuators are used in collocated sensor/driver pairs to form a feedback control system. The sensor produces a voltage that is proportional to the dynamic stress at the sensor location, and the driver produces a force that is proportional to the voltage applied to it. The analog control system amplifies and phase shifts the sensor signal to produce the voltage signal that is applied to the driver. The feedback control is demonstrated to increase the first mode damping in a cantilever beam by up to 100 percent, depending on the amplifier gain. The damping efficiency of the control system when the piezoelectrics are not optimally positioned at points of high stress in the beam is evaluated.

  12. Active Noise and Vibration Control Literature Survey: Controller Technologies

    DTIC Science & Technology

    1999-11-01

    control exclusively, but mathematical languages ( Matlab [The MathWorks, 1999], Matrix [Integrated Systems Inc, 1999) and, more recently, languages using...more efficient design process" [The Math Works, 1999]. Matlab and Simulink are powerful tools for dynamic systems identification. So, it is possible...to quickly obtain a numerical model of the physical system with Matlab . Moreover, Simulink enables the user to easily and quickly transpose the

  13. Establishing Approaches to Modeling the Ares I-X and Ares I Roll Control System with Free-stream Interaction

    NASA Technical Reports Server (NTRS)

    Pao, S. Paul; Deere, Karen A.; Abdol-Hamid, Khales S.

    2011-01-01

    Approaches were established for modeling the roll control system and analyzing the jet interactions of the activated roll control system on Ares-type configurations using the USM3D Navier-Stokes solver. Components of the modeling approach for the roll control system include a choice of turbulence models, basis for computing a dynamic equivalence of the real gas rocket exhaust flow in terms of an ideal gas, and techniques to evaluate roll control system performance for wind tunnel and flight conditions. A simplified Ares I-X configuration was used during the development phase of the roll control system modeling approach. A limited set of Navier-Stokes solutions was obtained for the purposes of this investigation and highlights of the results are included in this paper. The USM3D solutions were compared to equivalent solutions at select flow conditions from a real gas Navier- Stokes solver (Loci-CHEM) and a structured overset grid Navier-Stokes solver (OVERFLOW).

  14. Strategies for the photo-control of endogenous protein activity.

    PubMed

    Brechun, Katherine E; Arndt, Katja M; Woolley, G Andrew

    2016-11-28

    Photo-controlled or 'optogenetic' effectors interfacing with endogenous protein machinery allow the roles of endogenous proteins to be probed. There are two main approaches being used to develop optogenetic effectors: (i) caging strategies using photo-controlled conformational changes, and (ii) protein relocalization strategies using photo-controlled protein-protein interactions. Numerous specific examples of these approaches have been reported and efforts to develop general methods for photo-control of endogenous proteins are a current focus. The development of improved screening and selection methods for photo-switchable proteins would advance the field.

  15. Behavioral approach system activity and self-reported somatic symptoms in fibromyalgia: an exploratory study.

    PubMed

    Becerra-García, Juan A; Robles Jurado, Manuel J

    2014-01-01

    The first objective was to investigate the behavioural activity in the systems of Gray's theory; these are the Behavioural Inhibition System (BIS) and Behavioural Approach System (BAS), in fibromyalgia (FM) patients. The second aim was to assess in FM patients whether there is an association between BIS or BAS with self-reported somatic symptoms. Twenty FM patients and 20 healthy controls completed questionnaire measures of BIS and BAS activity (Sensitivity to Punishment and Sensitivity to Reward Questionnaire), self-reported somatic symptoms (Somatic Symptoms Scale Revised), positive and negative affect (Positive and Negative Affect Schedule) and health status (EuroQoL Visual Analogue Scale). The results showed that FM patients had lower Sensitivity to Reward (SR) scores than controls. The SR score correlated with different somatic symptoms groups. The partial correlation (controlling for other variables measured) showed that the SR score correlated specifically with musculoskeletal symptoms. Furthermore, in regression analysis, SR score significantly predicted musculoskeletal symptoms, after controlling for other variables measured in this study. Our findings suggest that FM patients show BAS hypoactivity. This BAS activity in FM is similar to patients with depression, where a lower BAS functioning has also been found. The BAS activity predicts the musculoskeletal self-reported symptoms in FM better than other measures included in this study. Although this is a preliminary study, it suggests the importance of BAS activity in FM.

  16. A Flight Control Approach for Small Reentry Vehicles

    NASA Technical Reports Server (NTRS)

    Bevacqoa, Tim; Adams, Tony; Zhu. J. Jim; Rao, P. Prabhakara

    2004-01-01

    Flight control of small crew return vehicles during atmospheric reentry will be an important technology in any human space flight mission undertaken in the future. The control system presented in this paper is applicable to small crew return vehicles in which reaction control system (RCS) thrusters are the only actuators available for attitude control. The control system consists of two modules: (i) the attitude controller using the trajectory linearization control (TLC) technique, and (ii) the reaction control system (RCS) control allocation module using a dynamic table-lookup technique. This paper describes the design and implementation of the TLC attitude control and the dynamic table-lookup RCS control allocation for nonimal flight along with design verification test results.

  17. Actively controlled shaft seals for aerospace applications

    NASA Technical Reports Server (NTRS)

    Salant, Richard F.

    1993-01-01

    An electronically controlled mechanical seal for use as the purge gas seal in a liquid oxygen turbo pump has been fabricated and tested under transient operating conditions. The thickness of the lubricating film is controlled by adjusting the coning of the carbon face. This is accomplished by applying a voltage to a piezoelectric actuator to which the carbon face is bonded. The seal has been operated with a closed-loop control system that utilizes either the leakage rate or the seal face temperature as the feedback. Both speed and pressure transients have been imposed on the seal. The transient tests have demonstrated that the seal is capable of maintaining low leakage rates while limiting the face temperatures.

  18. Broadband radiation modes: estimation and active control.

    PubMed

    Berkhoff, Arthur P

    2002-03-01

    In this paper we give a formulation of the most efficiently radiating vibration patterns of a vibrating body, the radiation modes, in the time domain. The radiation modes can be used to arrive at efficient weighting schemes for an array of sensors in order to reduce the controller dimensionality. Because these particular radiation modes are optimum in a broadband sense, they are termed broadband radiation modes. Methods are given to obtain these modes from measured data. The broadband radiation modes are used for the design of an actuator array in a feedback control system to reduce the sound power radiated from a plate. Three methods for the design of the actuator are compared, taking into account the reduction of radiated sound power in the controlled frequency range, but also the possible increase of radiated sound power in the uncontrolled frequency range.

  19. Active Control of Magnetically Levitated Bearings

    SciTech Connect

    BARNEY, PATRICK S.; LAUFFER, JAMES P.; REDMOND, JAMES M.; SULLIVAN, WILLIAM N.

    2001-03-01

    This report summarizes experimental and test results from a two year LDRD project entitled Real Time Error Correction Using Electromagnetic Bearing Spindles. This project was designed to explore various control schemes for levitating magnetic bearings with the goal of obtaining high precision location of the spindle and exceptionally high rotational speeds. As part of this work, several adaptive control schemes were devised, analyzed, and implemented on an experimental magnetic bearing system. Measured results, which indicated precision positional control of the spindle was possible, agreed reasonably well with simulations. Testing also indicated that the magnetic bearing systems were capable of very high rotational speeds but were still not immune to traditional structural dynamic limitations caused by spindle flexibility effects.

  20. ACOSS Twelve (Active Control of Space Structures)

    DTIC Science & Technology

    1982-12-01

    Analysis 10 1-VII Controller Robustness Investigation 12 I 1-VIII Robustness Definitions 12 1-lX Loop Transfer Recover on 2-Mode Example 15 I- X ...Results 2-V Correlation of Test and Analysis 67 2-VI Model Sensitivity 67 x 6. 1.0 ANALYTICAL RESEARCH FOR CONTROL METHODOLOGY DEVELOPMENT (TASK 1.0...include more modes than previously considered. The three I ’kA",PSD location Ix, V. 1I( ?.Is, 1 12 IV, Z) x * V. i Z is. 1 9. 9 (Y. 21 a I?. Iz 1

  1. Therapeutic antibody gene transfer: an active approach to passive immunity.

    PubMed

    Bakker, Joost M; Bleeker, Wim K; Parren, Paul W H I

    2004-09-01

    Advances in gene transfer approaches are enabling the possibility of applying therapeutic antibodies using DNA. In particular gene transfer in combination with electroporation is promising and can result in generating in vivo antibody concentrations in the low therapeutic range. However, several important problems need to be dealt with before antibody gene transfer can become a valuable supplement to the current therapies. As antibody production following gene transfer is difficult to control, the danger of inducing autoimmune conditions or uncontrollable side effects occurs in cases in which autologous antigens are targeted. It is suggested that the most promising area of application therefore appears to be infectious disease in which heterologous antigens are targeted and concerns for long-term antibody exposure are minimal. Finally, genes encoding fully human antibodies will enhance long-term expression and decrease problems linked to immunogenicity.

  2. Food control and a citizen science approach for improving teaching of Genetics in universities.

    PubMed

    Borrell, Y J; Muñoz-Colmenero, A M; Dopico, E; Miralles, L; Garcia-Vazquez, E

    2016-09-10

    A Citizen Science approach was implemented in the laboratory practices of Genetics at the University of Oviedo, related with the engaging topic of Food Control. Real samples of food products consumed by students at home (students as samplers) were employed as teaching material in three different courses of Genetics during the academic year 2014-2015: Experimental Methods in Food Production (MBTA) (Master level), and Applied Molecular Biology (BMA) and Conservation Genetics and Breeding (COMGE) (Bachelor/Degree level). Molecular genetics based on PCR amplification of DNA markers was employed for species identification of 22 seafood products in COMGE and MBTA, and for detection of genetically modified (GM) maize from nine products in BMA. In total six seafood products incorrectly labeled (27%), and two undeclared GM maize (22%) were found. A post-Laboratory survey was applied for assessing the efficacy of the approach for improving motivation in the Laboratory Practices of Genetics. Results confirmed that students that worked on their own samples from local markets were significantly more motivated and better evaluated their Genetic laboratory practices than control students (χ(2)  = 12.11 p = 0.033). Our results suggest that citizen science approaches could not be only useful for improving teaching of Genetics in universities but also to incorporate students and citizens as active agents in food control. © 2016 by The International Union of Biochemistry and Molecular Biology, 44(5):450-462, 2016.

  3. Pulley With Active Antifriction Actuator And Control

    NASA Technical Reports Server (NTRS)

    Ih, Che-Hang C.; Vivian, Howard C.

    1994-01-01

    Torque actuator and associated control system minimizes effective friction of rotary bearing. Motor exerts compensating torque in response to feedback from external optical sensor. Compensation torque nearly cancels frictional torque of shaft bearings. Also useful in reducing bearing friction in gyro-scopes, galvanometers, torquemeters, accelerometers, earth-motion detectors, and balances.

  4. Selective Activation and Disengagement of Moral Control.

    ERIC Educational Resources Information Center

    Bandura, Albert

    1990-01-01

    Analyzes psychological mechanisms by which moral control is selectively disengaged from inhumane conduct in ordinary and unusual circumstances. Explores the symptoms of moral exclusion as described in the literature. Presents categories that unify theory on moral exclusion and contribute practical classifications for use in empirical studies. (JS)

  5. Active Flow Control with Thermoacoustic Actuators

    DTIC Science & Technology

    2014-01-31

    dielectric barrier discharge ( DBD ) plasma actuators [4], or combustion powered actuators [5]. Compared to passive flow control techniques, such as vortex...space nor adding significant weight, which is similar to how DBD plasma actuators can be installed. 3 The sound generation mechanism, known as

  6. Limited Investigation of Active Feel Control Stick System (Active Stick)

    DTIC Science & Technology

    2009-06-01

    at VCORNER .............. 15 Figure 12: Pitch Rate Response to 1.5 g Commanded Force PTI at VHI ......................... 16 Figure 13: Pitch Angle...Response to 1.5 g Commanded Force PTI at VHI ...................... 17 Figure 14: Flight Control System Stick Attributes at VLO...23 Figure 19: Cooper-Harper Ratings for Head Down Display Task ( VHI ) ......................... 24 Figure 20: Fine

  7. An Information-Centric Approach to Autonomous Trajectory Planning Utilizing Optimal Control Techniques

    DTIC Science & Technology

    2009-09-01

    INFORMATION-CENTRIC APPROACH TO AUTONOMOUS TRAJECTORY PLANNING UTILIZING OPTIMAL CONTROL TECHNIQUES by Michael A. Hurni September 2009...Dissertation 4. TITLE AND SUBTITLE: An Information-centric Approach to Autonomous Trajectory Planning Utilizing Optimal Control Techniques 6...then finding a time- optimal time scaling for the path subject to the actuator limits. The direct approach searches for the trajectory directly

  8. Controlling self-sustained spiking activity by adding or removing one network link

    NASA Astrophysics Data System (ADS)

    Xu, Kesheng; Huang, Wenwen; Li, Baowen; Dhamala, Mukesh; Liu, Zonghua

    2013-06-01

    Being able to control the neuronal spiking activity in specific brain regions is central to a treatment scheme in several brain disorders such as epileptic seizures, mental depression, and Parkinson's diseases. Here, we present an approach for controlling self-sustained oscillations by adding or removing one directed network link in coupled neuronal oscillators, in contrast to previous approaches of adding stimuli or noise. We find that such networks can exhibit a variety of activity patterns such as on-off switch, sustained spikes, and short-term spikes. We derive the condition for a specific link to be the controller of the on-off effect. A qualitative analysis is provided to facilitate the understanding of the mechanism for spiking activity by adding one link. Our findings represent the first report on generating spike activity with the addition of only one directed link to a network and provide a deeper understanding of the microscopic roots of self-sustained spiking.

  9. Working with "Out-of-Control" Children--A Two-Systems Approach.

    PubMed

    Novick, Jack; Novick, Kerry Kelly

    2015-01-01

    The authors apply a two-systems approach to demonstrate improved treatment possibilities and outcomes in this group of children and suggest that psychoanalysis can be defined as a multimodal strengths-based learning experience. Using clinical material from the analysis of an aggressive, "out-of-control" child, they discuss how these behaviors and symptoms are better understood as an actively constructed effort at self-regulation than as a deficiency in capacity or primitive, lagging development. They illustrate how a two-systems framework can allow for an expanded repertoire of techniques and reclaim psychoanalytic concepts that have fallen into disuse.

  10. Trait Approach and Avoidance Motivation: Lateralized Neural Activity Associated with Executive Function

    PubMed Central

    Spielberg, Jeffrey M.; Miller, Gregory A.; Engels, Anna S.; Herrington, John D.; Sutton, Bradley P.; Banich, Marie T.; Heller, Wendy

    2010-01-01

    Motivation and executive function are both necessary for the completion of goal-directed behavior. Research investigating the manner in which these processes interact is beginning to emerge and has implicated middle frontal gyrus (MFG) as a site of interaction for relevant neural mechanisms. However, this research has focused on state motivation, and it has not examined functional lateralization. The present study examined the impact of trait levels of approach and avoidance motivation on neural processes associated with executive function. Functional magnetic resonance imaging was conducted while participants performed a color-word Stroop task. Analyses identified brain regions in which trait approach and avoidance motivation (measured by questionnaires) moderated activation associated with executive control. Approach was hypothesized to be associated with left-lateralized MFG activation, whereas avoidance was hypothesized to be associated with right-lateralized MFG activation. Results supported both hypotheses. Present findings implicate areas of middle frontal gyrus in top-down control to guide behavior in accordance with motivational goals. PMID:20728552

  11. Trait approach and avoidance motivation: lateralized neural activity associated with executive function.

    PubMed

    Spielberg, Jeffrey M; Miller, Gregory A; Engels, Anna S; Herrington, John D; Sutton, Bradley P; Banich, Marie T; Heller, Wendy

    2011-01-01

    Motivation and executive function are both necessary for the completion of goal-directed behavior. Research investigating the manner in which these processes interact is beginning to emerge and has implicated middle frontal gyrus (MFG) as a site of interaction for relevant neural mechanisms. However, this research has focused on state motivation, and it has not examined functional lateralization. The present study examined the impact of trait levels of approach and avoidance motivation on neural processes associated with executive function. Functional magnetic resonance imaging was conducted while participants performed a color-word Stroop task. Analyses identified brain regions in which trait approach and avoidance motivation (measured by questionnaires) moderated activation associated with executive control. Approach was hypothesized to be associated with left-lateralized MFG activation, whereas avoidance was hypothesized to be associated with right-lateralized MFG activation. Results supported both hypotheses. Present findings implicate areas of middle frontal gyrus in top-down control to guide behavior in accordance with motivational goals.

  12. Selected topics on the active control of helicopter aeromechanical and vibration problems

    NASA Technical Reports Server (NTRS)

    Friedmann, Peretz P.

    1994-01-01

    This paper describes in a concise manner three selected topics on the active control of helicopter aeromechanical and vibration problems. The three topics are as follows: (1) the active control of helicopter air-resonance using an LQG/LTR approach; (2) simulation of higher harmonic control (HHC) applied to a four bladed hingeless helicopter rotor in forward flight; and (3) vibration suppression in forward flight on a hingeless helicopter rotor using an actively controlled, partial span, trailing edge flap, which is mounted on the blade. Only a few selected illustrative results are presented. The results obtained clearly indicate that the partial span, actively controlled flap has considerable potential for vibration reduction in helicopter rotors.

  13. Active Control Technique Evaluation for Spacecraft (ACES)

    DTIC Science & Technology

    1988-06-16

    Due to Test Results 3-9 3.5 Representative Data 3-11 3.6 Control Model 3-21 4.0 Simulation 4-1 5.0 HAC/LAC 5-1 5.1 Theory 5-1...5.1.1 HAC Theory 5-1 5.1.2 LAC Theory 5-4 5.1.3 HAC/LAC Combined Control 5-6 5.1.4 HAC/LAC Applied to ACES 5-7 5.2 Model Selection and...5-39 5-50 6.0 Positivity 6-1 6-1 6-9 6-9 6-17 6-31 5.4 Observation 5.5 Test Results 5.6 Conclusions 6.1 Theory 6.2 Model

  14. Advanced Study for Active Noise Control in Aircraft (ASANCA)

    NASA Technical Reports Server (NTRS)

    Borchers, Ingo U.; Emborg, Urban; Sollo, Antonio; Waterman, Elly H.; Paillard, Jacques; Larsen, Peter N.; Venet, Gerard; Goeransson, Peter; Martin, Vincent

    1992-01-01

    Aircraft interior noise and vibration measurements are included in this paper from ground and flight tests. In addition, related initial noise calculations with and without active noise control are conducted. The results obtained to date indicate that active noise control may be an effective means for reducing the critical low frequency aircraft noise.

  15. A computer simulation approach to measurement of human control strategy

    NASA Technical Reports Server (NTRS)

    Green, J.; Davenport, E. L.; Engler, H. F.; Sears, W. E., III

    1982-01-01

    Human control strategy is measured through use of a psychologically-based computer simulation which reflects a broader theory of control behavior. The simulation is called the human operator performance emulator, or HOPE. HOPE was designed to emulate control learning in a one-dimensional preview tracking task and to measure control strategy in that setting. When given a numerical representation of a track and information about current position in relation to that track, HOPE generates positions for a stick controlling the cursor to be moved along the track. In other words, HOPE generates control stick behavior corresponding to that which might be used by a person learning preview tracking.

  16. An electronic control for an electrohydraulic active control landing gear for the F-4 aircraft

    NASA Technical Reports Server (NTRS)

    Ross, I.

    1982-01-01

    A controller for an electrohydraulic active control landing gear was developed for the F-4 aircraft. A controller was modified for this application. Simulation results indicate that during landing and rollout over repaired bomb craters the active gear effects a force reduction, relative to the passive gear, or approximately 70%.

  17. Poisson Parameters of Antimicrobial Activity: A Quantitative Structure-Activity Approach

    PubMed Central

    Sestraş, Radu E.; Jäntschi, Lorentz; Bolboacă, Sorana D.

    2012-01-01

    A contingency of observed antimicrobial activities measured for several compounds vs. a series of bacteria was analyzed. A factor analysis revealed the existence of a certain probability distribution function of the antimicrobial activity. A quantitative structure-activity relationship analysis for the overall antimicrobial ability was conducted using the population statistics associated with identified probability distribution function. The antimicrobial activity proved to follow the Poisson distribution if just one factor varies (such as chemical compound or bacteria). The Poisson parameter estimating antimicrobial effect, giving both mean and variance of the antimicrobial activity, was used to develop structure-activity models describing the effect of compounds on bacteria and fungi species. Two approaches were employed to obtain the models, and for every approach, a model was selected, further investigated and found to be statistically significant. The best predictive model for antimicrobial effect on bacteria and fungi species was identified using graphical representation of observed vs. calculated values as well as several predictive power parameters. PMID:22606039

  18. Novel electro-fenton approach for regeneration of activated carbon.

    PubMed

    Bañuelos, Jennifer A; Rodríguez, Francisco J; Manríquez Rocha, Juan; Bustos, Erika; Rodríguez, Adrián; Cruz, Julio C; Arriaga, L G; Godínez, Luis A

    2013-07-16

    An electro-Fenton-based method was used to promote the regeneration of granular activated carbon (GAC) previously adsorbed with toluene. Electrochemical regeneration experiments were carried out using a standard laboratory electrochemical cell with carbon paste electrodes and a batch electrochemical reactor. For each system, a comparison was made using FeSO4 as a precursor salt in solution (homogeneous system) and an Fe-loaded ion-exchange resin (Purolite C-100, heterogeneous system), both in combination with electrogenerated H2O2 at the GAC cathode. In the two cases, high regeneration efficiencies were obtained in the presence of iron using appropriate conditions of applied potential and adsorption-polarization time. Consecutive loading and regeneration cycles of GAC were performed in the reactor without great loss of the adsorption properties, only reducing the regeneration efficiency by 1% per cycle during 10 cycles of treatment. Considering that, in the proposed resin-containing process, the use of Fe salts is avoided and that GAC cathodic polarization results in efficient cleaning and regeneration of the adsorbent material, this novel electro-Fenton approach could constitute an excellent alternative for regenerating activated carbon when compared to conventional methods.

  19. Computational Fluid Dynamics Simulation Study of Active Power Control in Wind Plants

    SciTech Connect

    Fleming, Paul; Aho, Jake; Gebraad, Pieter; Pao, Lucy; Zhang, Yingchen

    2016-08-01

    This paper presents an analysis performed on a wind plant's ability to provide active power control services using a high-fidelity computational fluid dynamics-based wind plant simulator. This approach allows examination of the impact on wind turbine wake interactions within a wind plant on performance of the wind plant controller. The paper investigates several control methods for improving performance in waked conditions. One method uses wind plant wake controls, an active field of research in which wind turbine control systems are coordinated to account for their wakes, to improve the overall performance. Results demonstrate the challenge of providing active power control in waked conditions but also the potential methods for improving this performance.

  20. Controllability and hippocampal activation during pain expectation in fibromyalgia syndrome.

    PubMed

    González-Roldán, Ana María; Bomba, Isabelle C; Diesch, Eugen; Montoya, Pedro; Flor, Herta; Kamping, Sandra

    2016-12-01

    To examine the role of perceived control in pain perception, fibromyalgia patients and healthy controls participated in a reaction time experiment under different conditions of pain controllability. No significant differences between groups were found in pain intensity and unpleasantness ratings. However, during the expectation of uncontrollable pain, patients compared to controls showed higher hippocampal activation. In addition, hippocampal activity during the pain expectation period predicted activation of the posterior cingulate cortex (PCC), precuneus and hippocampus during pain stimulation in fibromyalgia patients. The increased activation of the hippocampus during pain expectation and subsequent activation of the PCC/precuneus during the lack of control phase points towards an influence of pain perception through heightening of alertness and anxiety responses to pain in fibromyalgia patients.

  1. Elements of active vibration control for rotating machinery

    NASA Technical Reports Server (NTRS)

    Ulbrich, Heinz

    1990-01-01

    The success or failure of active vibration control is determined by the availability of suitable actuators, modeling of the entire system including all active elements, positioning of the actuators and sensors, and implementation of problem-adapted control concepts. All of these topics are outlined and their special problems are discussed in detail. Special attention is given to efficient modeling of systems, especially for considering the active elements. Finally, design methods for and the application of active vibration control on rotating machinery are demonstrated by several real applications.

  2. Control surface spanwise placement in active flutter suppression systems

    NASA Technical Reports Server (NTRS)

    Nissim, E.; Burken, J. J.

    1989-01-01

    All flutter suppression systems require sensors to detect the movement of the lifting surface and to activate a control surface according to a synthesized control law. Most of the work performed to date relates to the development of control laws based on predetermined locations of sensors and control surfaces. These locations of sensors and control surfaces are determined either arbitrarily, or by means of a trial and error procedure. The aerodynamic energy concept indicates that the sensors should be located within the activated strip. Furthermore, the best chordwise location of a sensor activating a T.E. control surface is around the 65 percent chord location. The best chordwise location for a sensor activating a L.E. surface is shown to lie upstream of the wing (around 20 percent upstream of the leading edge), or alternatively, two sensors located along the same chord should be used.

  3. New Highly Dynamic Approach for Thrust Vector Control

    NASA Astrophysics Data System (ADS)

    Hecht, M.; Ettl, J.; Grothe, D.; Hrbud, I.

    2015-09-01

    For a new launcher system a thrust vector control system is needed. This launch vehicle system consists of two rockets which are namely the VS-50 (two-stage suborbital vehicle) and the VLM-1 (three-stage microsatellite launch vehicle). VLM-1 and VS-50 are developed in a cooperation between the German Aerospace Center (DLR) and the Brazilian Aeronautics and Space Institute (IAE). To keep these two rockets on its trajectory during flight a highly dynamic thrust vector control system is required. For the purpose of developing such a highly dynamic thrust vector control system a master thesis was written by the author. The development includes all mechanical constructions as well as control algorithms and electronics design. Moreover an optimization of control algorithms was made to increase the dynamic capabilities of the thrust vector control system. The composition of the right components plus the sophisticated control algorithm make the thrust vector control system highly dynamic.

  4. Optimal Control of Active Recoil Mechanisms

    DTIC Science & Technology

    1977-02-01

    forces from 25 to 2.5% for lower zones and cavitation was avoided for zone 8. Tachometer feedback was shown to be effective for low zones. The...concept of feedback control system coupled with optimization procedure to design recoil mechanisms was demonstrated to be an efficient and very effective ...122o •nl260 .01300 .01340 .01380 • ouzo #01460 •01500 •01540 •01580 •0162" .0166 i 309o,6 504P.6 9964.5 10075,9 39121.5 75397.3

  5. A novel approach to image neural activity directly by MRI

    NASA Astrophysics Data System (ADS)

    Singh, Manbir; Sungkarat, Witaya

    2005-04-01

    Though an approach to image the electrical activity of neurons directly by detecting phase shifts in MRI was first reported in 1991, results to-date remain equivocal due to the low signal-to-noise ratio. The objective of this work was to develop a stimulus-presentation and data acquisition strategy specially geared to detect phase-dispersion effects of neuronal currents within 10-100 ms following stimulation. The key feature is to set the repeated MR data acquisition time TR and the stimulus presentation interval (TI) slightly different from each other so that the time at which images are acquired shifts gradually from one acquisition to the next with respect to stimulus onset. For example, at TR=275ms and 4 Hz stimulus presentation (TI=250ms), initial synchronization of the stimulus onset and MR acquisition would result in the first image being acquired at a latency of 0+/- (temporal width of data acquisition window), second image at a latency of 25ms, third image at a latency of 50ms and so on up to a latency of 250ms, at which time the stimulus and data acquisition times would become re-synchronized to once again acquire an image at latency=0. Human data were acquired on a 1.5T GE EXCITE scanner from two 8mm thick contiguous slices bracketing the calcarine fissure during a checkerboard flashing at 4 Hz. Preliminary results show activity in the visual cortex at latencies consistent with EEG studies, suggesting the potential of this methodology to image neural activity directly.

  6. Active control of compressible flows on a curved surface

    NASA Technical Reports Server (NTRS)

    Maestrello, L.; Parikh, P.; Bayliss, A.; Turkel, E.

    1985-01-01

    The effect of localized, time periodic surface heating and cooling over a curved surface is studied. This is a mechanism for the active control of unstable disturbances by phase cancellation and reinforcement. It is shown that the pressure gradient induced by the curvature significantly enhances the effectiveness of this form of active control. In particular, by appropriate choice of phase, active surface heating can completely stabilize and unstable wave.

  7. Active control of compressible flows on a curved surface

    NASA Technical Reports Server (NTRS)

    Maestrello, L.; Bayliss, A.; Parikh, P.; Turkel, E.

    1985-01-01

    The effect of localized, time periodic surface heating and cooling over a curved surface is studied. This is a mechanism for the active control of unstable disturbances by phase cancellation and reinforcement. It is shown that the pressure gradient induced by the curvature significantly enhances the effectiveness of this form of active control. In particular, by appropriate choice of phase, active surface heating can completely stabilize an unstable wave.

  8. Receding horizon control of nonlinear systems: A control Lyapunov function approach

    NASA Astrophysics Data System (ADS)

    Jadbabaie, Ali

    (restricted, of course, to the infinite horizon domain). Moreover, it is easily seen that both CLF and infinite horizon optimal control approaches are limiting cases of our receding horizon strategy. The key results are illustrated using a familiar example, the inverted pendulum, as well as models of the Caltech ducted fan at hover and forward flight, where significant improvements in guaranteed region of operation and cost are noted. We also develop an optimization based scheme for generation of aggressive trajectories for hover and forward flight, models of the Caltech ducted fan experiment, using a technique known as trajectory morphing. The main idea behind trajectory morphing is to develop a simplified model of the nonlinear system and solve, the trajectory generation problem for that model. The resulting trajectory is then used as a reference in a receding horizon optimization scheme to generate trajectories of the original nonlinear system. Several aggressive trajectories are obtained in this fashion for the forward flight model of the Caltech ducted fan experiment.

  9. A convergent diffusion and social marketing approach for disseminating proven approaches to physical activity promotion.

    PubMed

    Dearing, James W; Maibach, Edward W; Buller, David B

    2006-10-01

    Approaches from diffusion of innovations and social marketing are used here to propose efficient means to promote and enhance the dissemination of evidence-based physical activity programs. While both approaches have traditionally been conceptualized as top-down, center-to-periphery, centralized efforts at social change, their operational methods have usually differed. The operational methods of diffusion theory have a strong relational emphasis, while the operational methods of social marketing have a strong transactional emphasis. Here, we argue for a convergence of diffusion of innovation and social marketing principles to stimulate the efficient dissemination of proven-effective programs. In general terms, we are encouraging a focus on societal sectors as a logical and efficient means for enhancing the impact of dissemination efforts. This requires an understanding of complex organizations and the functional roles played by different individuals in such organizations. In specific terms, ten principles are provided for working effectively within societal sectors and enhancing user involvement in the processes of adoption and implementation.

  10. Semi Active Control of Civil Structures, Analytical and Numerical Studies

    NASA Astrophysics Data System (ADS)

    Kerboua, M.; Benguediab, M.; Megnounif, A.; Benrahou, K. H.; Kaoulala, F.

    Structural control for civil structures was born out of a need to provide safer and more efficient designs with the reality of limited resources. The purpose of structural control is to absorb and to reflect the energy introduced by dynamic loads such as winds, waves, earthquakes, and traffic. Today, the protection of civil structures from severe dynamic loading is typically achieved by allowing the structures to be damaged. Semi-active control devices, also called "smart" control devices, assume the positive aspects of both the passive and active control devices. A semi-active control strategy is similar to the active control strategy. Only here, the control actuator does not directly apply force to the structure, but instead it is used to control the properties of a passive energy device, a controllable passive damper. Semi-active control strategies can be used in many of the same civil applications as passive and active control. One method of operating smart cable dampers is in a purely passive capacity, supplying the dampers with constant optimal voltage. The advantages to this strategy are the relative simplicity of implementing the control strategy as compared to a smart or active control strategy and that the dampers are more easily optimally tuned in- place, eliminating the need to have passive dampers with unique optimal damping coefficients. This research investigated semi-active control of civil structures for natural hazard mitigation. The research has two components, the seismic protection of buildings and the mitigation of wind-induced vibration in structures. An ideal semi-active motion equation of a composite beam that consists of a cantilever beam bonded with a PZT patch using Hamilton's principle and Galerkin's method was treated. A series R-L and a parallel R-L shunt circuits are coupled into the motion equation respectively by means of the constitutive relation of piezoelectric material and Kirchhoff's law to control the beam vibration. A

  11. Active Control of Solar Array Dynamics During Spacecraft Maneuvers

    NASA Technical Reports Server (NTRS)

    Ross, Brant A.; Woo, Nelson; Kraft, Thomas G.; Blandino, Joseph R.

    2016-01-01

    Recent NASA mission plans require spacecraft to undergo potentially significant maneuvers (or dynamic loading events) with large solar arrays deployed. Therefore there is an increased need to understand and possibly control the nonlinear dynamics in the spacecraft system during such maneuvers. The development of a nonlinear controller is described. The utility of using a nonlinear controller to reduce forces and motion in a solar array wing during a loading event is demonstrated. The result is dramatic reductions in system forces and motion during a 10 second loading event. A motion curve derived from the simulation with the closed loop controller is used to obtain similar benefits with a simpler motion control approach.

  12. Active vibration control of a full scale aircraft wing using a reconfigurable controller

    NASA Astrophysics Data System (ADS)

    Prakash, Shashikala; Renjith Kumar, T. G.; Raja, S.; Dwarakanathan, D.; Subramani, H.; Karthikeyan, C.

    2016-01-01

    This work highlights the design of a Reconfigurable Active Vibration Control (AVC) System for aircraft structures using adaptive techniques. The AVC system with a multichannel capability is realized using Filtered-X Least Mean Square algorithm (FxLMS) on Xilinx Virtex-4 Field Programmable Gate Array (FPGA) platform in Very High Speed Integrated Circuits Hardware Description Language, (VHDL). The HDL design is made based on Finite State Machine (FSM) model with Floating point Intellectual Property (IP) cores for arithmetic operations. The use of FPGA facilitates to modify the system parameters even during runtime depending on the changes in user's requirements. The locations of the control actuators are optimized based on dynamic modal strain approach using genetic algorithm (GA). The developed system has been successfully deployed for the AVC testing of the full-scale wing of an all composite two seater transport aircraft. Several closed loop configurations like single channel and multi-channel control have been tested. The experimental results from the studies presented here are very encouraging. They demonstrate the usefulness of the system's reconfigurability for real time applications.

  13. Generalized internal model robust control for active front steering intervention

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  14. A modelling approach to support dynamic decision-making in the control of FMD epidemics.

    PubMed

    Ge, Lan; Mourits, Monique C M; Kristensen, Anders R; Huirne, Ruud B M

    2010-07-01

    Most studies on control strategies for contagious diseases such as foot-and-mouth disease (FMD) evaluate pre-defined control strategies and imply static decision-making during epidemic control. Such a static approach contradicts the dynamic nature of the decision-making process during epidemic control. This paper presents an integrated epidemic-economic modelling approach to support dynamic decision-making in controlling FMD epidemics. This new modelling approach reflects ongoing uncertainty about epidemic growth during epidemic control and provides information required by a dynamic decision process. As demonstrated for a Dutch FMD-case, the modelling approach outperforms static evaluation of pre-fixed control strategies by: (1) providing guidance to decision-making during the entire control process; and (2) generating more realistic estimation of the costs of overreacting or underreacting in choosing control options.

  15. Combustion diagnostic for active engine feedback control

    DOEpatents

    Green, Jr., Johney Boyd; Daw, Charles Stuart; Wagner, Robert Milton

    2007-10-02

    This invention detects the crank angle location where combustion switches from premixed to diffusion, referred to as the transition index, and uses that location to define integration limits that measure the portions of heat released during the combustion process that occur during the premixed and diffusion phases. Those integrated premixed and diffusion values are used to develop a metric referred to as the combustion index. The combustion index is defined as the integrated diffusion contribution divided by the integrated premixed contribution. As the EGR rate is increased enough to enter the low temperature combustion regime, PM emissions decrease because more of the combustion process is occurring over the premixed portion of the heat release rate profile and the diffusion portion has been significantly reduced. This information is used to detect when the engine is or is not operating in a low temperature combustion mode and provides that feedback to an engine control algorithm.

  16. Active shear flow control for improved combustion

    NASA Astrophysics Data System (ADS)

    Gutmark, E.; Parr, T. P.; Hanson-Parr, D. M.; Schadow, K. C.

    1990-01-01

    The acoustical and fluid dynamic facets of an excited premixed flame were studied experimentally to evaluate possibilities for development of a stabilizing closed-loop control system. The flame was analyzed as a nonlinear system which includes different subcomponents: acoustics, fluid dynamics, and chemical reaction. Identification of the acoustical and fluid dynamics subsystems is done by analyzing the transfer function, which was obtained by driving the system with both white-noise and a frequency-sweeping sine-wave. The features obtained by this analysis are compared to results of flow visualization and hot-wire flow-field and spectral measurements. The acoustical subsystem is determined by the resonant acoustic modes of the settling chamber. These modes are subsequently filtered and amplified by the flow shear layer, whose instability characteristics are dominated by the preferred mode frequency.

  17. Impulsive approach tendencies towards physical activity and sedentary behaviors, but not reflective intentions, prospectively predict non-exercise activity thermogenesis.

    PubMed

    Cheval, Boris; Sarrazin, Philippe; Pelletier, Luc

    2014-01-01

    Understanding the determinants of non-exercise activity thermogenesis (NEAT) is crucial, given its extensive health benefits. Some scholars have assumed that a proneness to react differently to environmental cues promoting sedentary versus active behaviors could be responsible for inter-individual differences in NEAT. In line with this reflection and grounded on the Reflective-Impulsive Model, we test the assumption that impulsive processes related to sedentary and physical activity behaviors can prospectively predict NEAT, operationalized as spontaneous effort exerted to maintain low intensity muscle contractions within the release phases of an intermittent maximal isometric contraction task. Participants (n = 91) completed a questionnaire assessing their intentions to adopt physical activity behaviors and a manikin task to assess impulsive approach tendencies towards physical activity behaviors (IAPA) and sedentary behaviors (IASB). Participants were then instructed to perform a maximal handgrip strength task and an intermittent maximal isometric contraction task. As hypothesized, multilevel regression analyses revealed that spontaneous effort was (a) positively predicted by IAPA, (b) negatively predicted by IASB, and (c) was not predicted by physical activity intentions, after controlling for some confounding variables such as age, sex, usual PA level and average force provided during the maximal-contraction phases of the task. These effects remained constant throughout all the phases of the task. This study demonstrated that impulsive processes may play a unique role in predicting spontaneous physical activity behaviors. Theoretically, this finding reinforces the utility of a motivational approach based on dual-process models to explain inter-individual differences in NEAT. Implications for health behavior theories and behavior change interventions are outlined.

  18. Dynamics Control Approaches to Improve Vibratory Environment of the Helicopter Aircrew

    NASA Astrophysics Data System (ADS)

    Wickramasinghe, Viresh Kanchana

    Although helicopter has become a versatile mode of aerial transportation, high vibration levels leads to poor ride quality for its passengers and aircrew. Undesired vibration transmitted through the helicopter seats have been known to cause fatigue and discomfort to the aircrew in the short-term as well as neck strain and back pain injuries due to long-term exposure. This research study investigated the use of novel active as well as passive methodologies integrated in helicopter seats to mitigate the aircrew exposure to high vibration levels. Due to significantly less certification effort required to modify the helicopter seat structure, application of novel technologies to the seat is more practical compared to flight critical components such as the main rotor to reduce aircrew vibration. In particular, this research effort developed a novel adaptive seat mount approach based on active vibration control technology. This novel design that incorporated two stacked piezoelectric actuators as active struts increases the bending stiffness to avoid the low frequency resonance while generating forces to counteract higher harmonic vibration peaks. A real-time controller implemented using a feed-forward algorithm based on adaptive notches counteracted the forced vibration peaks while a robust feedback control algorithm suppressed the resonance modes. The effectiveness of the adaptive seat mount system was demonstrated through extensive closed-loop control tests on a full-scale helicopter seat using representative helicopter floor vibration profiles. Test results concluded that the proposed adaptive seat mount approach based on active control technology is a viable solution for the helicopter seat vibration control application. In addition, a unique flight test using a Bell-412 helicopter demonstrated that the aircrew is exposed to high levels of vibration during flight and that the whole body vibration spectrum varied substantially depending on operating conditions as

  19. Anxiety, not anger, induces inflammatory activity: An avoidance/approach model of immune system activation.

    PubMed

    Moons, Wesley G; Shields, Grant S

    2015-08-01

    Psychological stressors reliably trigger systemic inflammatory activity as indexed by levels of proinflammatory cytokines. This experiment demonstrates that one's specific emotional reaction to a stressor may be a significant determinant of whether an inflammatory reaction occurs in response to that stressor. Based on extant correlational evidence and theory, a causal approach was used to determine whether an avoidant emotion (anxiety) triggers more inflammatory activity than an approach emotion (anger). In an experimental design (N = 40), a 3-way Emotion Condition × Time × Analyte interaction revealed that a writing-based anxiety induction, but not a writing-based anger induction, increased mean levels of interferon-γ (IFN- γ) and interleukin-1β (IL-1β), but not interleukin-6 (IL-6) in oral mucous, F(2, 54) = 4.64, p = .01, ηp(²) = .15. Further, self-reported state anxiety predicted elevated levels of proinflammatory cytokines, all ΔR(²) >.06, ps <.04, but self-reported state anger did not. These results constitute the first evidence to our knowledge that specific negative emotions can differentially cause inflammatory activity and support a theoretical model explaining these effects based on the avoidance or approach motivations associated with emotions.

  20. A modular approach to multi-robot control

    SciTech Connect

    Anderson, R.J.; Lilly, K.W.

    1996-03-01

    The ability to rapidly command multi-robot behavior is crucial for the acceptance and effective utilization of multiple robot control. To achieve this, a modular- multiple robot control solution is being, pursued using the SMART modular control architecture. This paper investigates the development of a new dual-arm kinematics module (DUAL-KLN) which allows multiple robots, previously controlled as separate stand-alone systems, to be controlled as a coordinated multi-robot system. The DUAL-KIN module maps velocity and force information from a center point of interest on a grasped object to the tool centers of each grasping robot. Three-port network equations are used and mapped into the scattering operator domain in a computationally efficient form. Application examples of the DUAL-KLN module in multi-robot coordinated control are given.

  1. Biomimetic approaches to the control of underwater walking machines.

    PubMed

    Ayers, Joseph; Witting, Jan

    2007-01-15

    We have developed a biomimetic robot based on the American lobster. The robot is designed to achieve the performance advantages of the animal model by adopting biomechanical features and neurobiological control principles. Three types of controllers are described. The first is a state machine based on the connectivity and dynamics of the lobster central pattern generator (CPG). The state machine controls myomorphic actuators based on shape memory alloys (SMAs) and responds to environmental perturbation through sensors that employ a labelled-line code. The controller supports a library of action patterns and exteroceptive reflexes to mediate tactile navigation, obstacle negotiation and adaptation to surge. We are extending this controller to neuronal network-based models. A second type of leg CPG is based on synaptic networks of electronic neurons and has been adapted to control the SMA actuated leg. A brain is being developed using layered reflexes based on discrete time map-based neurons.

  2. Controller reduction for effective interdisciplinary design of active structures

    NASA Technical Reports Server (NTRS)

    Balas, Mark J.; Quan, Ralph

    1989-01-01

    Control problems of large aerospace structures are intrinsically interdisciplinary and require strategies which address the complete interaction between flexible structures, electromechanical actuators and sensors, and feedback control algorithms. Current research and future directions which will require an interdisciplinary team effort in dynamics, control and optimization of such structures are being surveyed. It is generally agreed that the dynamics of space structures require large scale discrete modeling, resulting in thousands of discrete unknowns. Proven control strategies, on the other hand, employ a low order controller that is based on a reduced order model of structures. Integration of such low order controllers and large scale dynamics models often leads to serious deterioration of the closed loop stability margin and even instability. To alleviate this stability deterioration while low order controllers remain effective, the following approach was investigated: (1) retain low order controllers based on reduced order models of structures as the basic control strategy; (2) introduce a compensator that will directly account for the deterioration of stability margin due to controller-structure integration; and (3) assess overall performance of the integrated control structure system by developing measures of suboptimality in the combination of (1) and (2). The benefits include: simplicity in the design of basic controllers, thus facilitating the optimization of structure control interactions; increased understanding of the roles of the compensator so as to modify the structure as well as the basic controller, if necessary, for improved performance; and adaptability to localize controllers by viewing the compensator as a systems integration filter.

  3. An Integrated Navigation Approach for Ship Track Control

    DTIC Science & Technology

    1992-10-01

    integral heading compensation ( PI control ) to the autopilot, as required. Switches 1 End 2 provide a means of indicating the application status of the...0.1 nautical mile or less. The autopilot heading correction, ship’s distance cross track and PI control law •aphs, provided in Figures 4, 5, and 6...theoretical PI control law correctin exceeded the maximum 2 degree per increment applied correction limitation. In Figure 4, the size of an increment is

  4. Active control of transmission loss with smart foams.

    PubMed

    Kundu, Abhishek; Berry, Alain

    2011-02-01

    Smart foams combine the complimentary advantages of passive foam material and spatially distributed piezoelectric actuator embedded in it for active noise control applications. In this paper, the problem of improving the transmission loss of smart foams using active control strategies has been investigated both numerically and experimentally inside a waveguide under the condition of plane wave propagation. The finite element simulation of a coupled noise control system has been undertaken with three different smart foam designs and their effectiveness in cancelling the transmitted wave downstream of the smart foam have been studied. The simulation results provide insight into the physical phenomenon of active noise cancellation and explain the impact of the smart foam designs on the optimal active control results. Experimental studies aimed at implementing the real-time control for transmission loss optimization have been performed using the classical single input/single output filtered-reference least mean squares algorithm. The active control results with broadband and single frequency primary source inputs demonstrate a good improvement in the transmission loss of the smart foams. The study gives a comparative description of the transmission and absorption control problems in light of the modification of the vibration response of the piezoelectric actuator under active control.

  5. Flutter suppression and gust alleviation using active controls

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1974-01-01

    The effects of active controls on the suppression of flutter and gust alleviation of two different types of subsonic aircraft (the Arava, twin turboprop STOL transport, and the Westwind twin-jet business transport) are investigated. The active controls are introduced in pairs which include, in any chosen wing strip, a leading-edge (LE) control and a trailing-edge (TE) control. Each control surface is allowed to be driven by a combined linear-rotational sensor system, located on the activated strip. The control law, which translates the sensor signals into control surface rotations, is based on the concept of aerodynamic energy. The results indicate the extreme effectiveness of the active systems in controlling flutter. A single system spanning 10% of the wing semispan made the Arava flutter-free, and a similar active system, for the Westwind aircraft, yielded a reduction of 75% in the maximum bending moment of the wing and a reduction of 90% in the acceleration of the cg of the aircraft. Results for simultaneous activation of several LE - TE systems are presented. Further work needed to bring the investigation to completion is also discussed.

  6. Various applications of Active Field Control (AFC)

    NASA Astrophysics Data System (ADS)

    Watanabe, Takayuki; Miyazaki, Hideo; Kishinaga, Shinji; Kawakami, Fukushi

    2003-10-01

    AFC is an electro-acoustic enhancement system, which has been under development at Yamaha Corporation. In this paper, several types of various AFC applications are discussed, while referring to representative projects for each application in Japan. (1) Realization of acoustics in a huge hall to classical music program, e.g., Tokyo International Forum. This venue is a multipurpose hall with approximately 5000 seats. AFC achieves loudness and reverberance equivalent to those of a hall with 2500 seats or fewer. (2) Optimization of acoustics for a variety of programs, e.g., Arkas Sasebo. AFC is used to create the optimum acoustics for each program, such as reverberance for classical concerts, acoustical support for opera singers, uniformity throughout the hall from the stage to under-balcony area, etc. (3) Control of room shape acoustical effect, e.g., Osaka Central Public Hall: In this renovation project, preservation of historically important architecture in the original form is required. AFC is installed to vary only the acoustical environment without architectural changes. (4) Assistance with crowd enthusiasm for sports entertainment, e.g., Tokyo Metropolitan Gymnasium. In this venue, which is designed as a very absorptive space for speech intelligibility, AFC is installed to enhance the atmosphere of live sports entertainment.

  7. Agile development approach for the observatory control software of the DAG 4m telescope

    NASA Astrophysics Data System (ADS)

    Güçsav, B. Bülent; ćoker, Deniz; Yeşilyaprak, Cahit; Keskin, Onur; Zago, Lorenzo; Yerli, Sinan K.

    2016-08-01

    Observatory Control Software for the upcoming 4m infrared telescope of DAG (Eastern Anatolian Observatory in Turkish) is in the beginning of its lifecycle. After the process of elicitation-validation of the initial requirements, we have been focused on preparation of a rapid conceptual design not only to see the big picture of the system but also to clarify the further development methodology. The existing preliminary designs for both software (including TCS and active optics control system) and hardware shall be presented here in brief to exploit the challenges the DAG software team has been facing with. The potential benefits of an agile approach for the development will be discussed depending on the published experience of the community and on the resources available to us.

  8. Active music therapy approach for stroke patients in the post-acute rehabilitation.

    PubMed

    Raglio, Alfredo; Zaliani, Alberto; Baiardi, Paola; Bossi, Daniela; Sguazzin, Cinzia; Capodaglio, Edda; Imbriani, Chiara; Gontero, Giulia; Imbriani, Marcello

    2017-01-30

    Guidelines in stroke rehabilitation recommend the use of a multidisciplinary approach. Different approaches and techniques with music are used in the stroke rehabilitation to improve motor and cognitive functions but also psychological outcomes. In this randomized controlled pilot trial, relational active music therapy approaches were tested in the post-acute phase of disease. Thirty-eight hospitalized patients with ischemic and hemorrhagic stroke were recruited and allocated in two groups. The experimental group underwent the standard of care (physiotherapy and occupational therapy daily sessions) and relational active music therapy treatments. The control group underwent the standard of care only. Motor functions and psychological aspects were assessed before and after treatments. Music therapy process was also evaluated using a specific rating scale. All groups showed a positive trend in quality of life, functional and disability levels, and gross mobility. The experimental group showed a decrease of anxiety and, in particular, of depression (p = 0.016). In addition, the strength of non-dominant hand (grip) significantly increased in the experimental group (p = 0.041). Music therapy assessment showed a significant improvement over time of non-verbal and sonorous-music relationships. Future studies, including a greater number of patients and follow-up evaluations, are needed to confirm promising results of this study.

  9. Active Control of Fan Noise: Feasibility Study. Volume 3; Active Fan Noise Cancellation in the NASA Lewis Active Noise Control Fan Facility

    NASA Technical Reports Server (NTRS)

    Pla, Frederic G.; Hu, Ziqiang; Sutliff, Daniel L.

    1996-01-01

    This report describes the Active Noise Cancellation (ANC) System designed by General Electric and tested in the NASA Lewis Research Center's (LERC) 48 inch Active Noise Control Fan (ANCF). The goal of this study is to assess the feasibility of using wall mounted secondary acoustic sources and sensors within the duct of a high bypass turbofan aircraft engine for global active noise cancellation of fan tones. The GE ANC system is based on a modal control approach. A known acoustic mode propagating in the fan duct is canceled using an array of flush-mounted compact sound sources. The canceling modal signal is generated by a modal controller. Inputs to the controller are signals from a shaft encoder and from a microphone array which senses the residual acoustic mode in the duct. The key results are that the (6,0) was completely eliminated at the 920 Hz design frequency and substantially reduced elsewhere. The total tone power was reduced 6.8 dB (out of a possible 9.8 dB). Farfield reductions of 15 dB (SPL) were obtained. The (4,0) and (4,1) modes were reduced simultaneously yielding a 15 dB PWL decrease. The results indicate that global attenuation of PWL at the target frequency was obtained in the aft quadrant using an ANC actuator and sensor system totally contained within the duct. The quality of the results depended on precise mode generation. High spillover into spurious modes generated by the ANC actuator array caused less than optimum levels of PWL reduction. The variation in spillover is believed to be due to calibration procedure, but must be confirmed in subsequent tests.

  10. Integral approaches to wastewater treatment plant upgrading for odor prevention: Activated Sludge and Oxidized Ammonium Recycling.

    PubMed

    Estrada, José M; Kraakman, N J R; Lebrero, R; Muñoz, R

    2015-11-01

    Traditional physical/chemical end-of-the-pipe technologies for odor abatement are relatively expensive and present high environmental impacts. On the other hand, biotechnologies have recently emerged as cost-effective and environmentally friendly alternatives but are still limited by their investment costs and land requirements. A more desirable approach to odor control is the prevention of odorant formation before being released to the atmosphere, but limited information is available beyond good design and operational practices of the wastewater treatment process. The present paper reviews two widely applicable and economic alternatives for odor control, Activated Sludge Recycling (ASR) and Oxidized Ammonium Recycling (OAR), by discussing their fundamentals, key operating parameters and experience from the available pilot and field studies. Both technologies present high application potential using readily available plant by-products with a minimum plant upgrading, and low investment and operating costs, contributing to the sustainability and economic efficiency of odor control at wastewater treatment facilities.

  11. Artificial Intelligence Approach to Support Statistical Quality Control Teaching

    ERIC Educational Resources Information Center

    Reis, Marcelo Menezes; Paladini, Edson Pacheco; Khator, Suresh; Sommer, Willy Arno

    2006-01-01

    Statistical quality control--SQC (consisting of Statistical Process Control, Process Capability Studies, Acceptance Sampling and Design of Experiments) is a very important tool to obtain, maintain and improve the Quality level of goods and services produced by an organization. Despite its importance, and the fact that it is taught in technical and…

  12. On-line Monitoring and Active Control for Transformer Noise

    NASA Astrophysics Data System (ADS)

    Liang, Jiabi; Zhao, Tong; Tian, Chun; Wang, Xia; He, Zhenhua; Duan, Lunfeng

    This paper introduces the system for on-line monitoring and active noise control towards the transformer noise based on LabVIEW and the hardware equipment including the hardware and software. For the hardware part, it is mainly focused on the composition and the role of hardware devices, as well as the mounting location in the active noise control experiment. And the software part introduces the software flow chats, the measurement and analysis module for the sound pressure level including A, B, C weighting methods, the 1/n octave spectrum and the power spectrum, active noise control module and noise data access module.

  13. [Actuator placement for active sound and vibration control

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Two refereed journal publications and ten talks given at conferences, seminars, and colloquia resulted from research supported by NASA. They are itemized in this report. The two publications were entitled "Reactive Tabu and Search Sensor Selection in Active Structural Acoustic Control Problems" and "Quelling Cabin Noise in Turboprop Aircraft via Active Control." The conference presentations covered various aspects of actuator placement, including location problems, for active sound and vibration control of cylinders, of commuter jets, of propeller driven or turboprop aircraft, and for quelling aircraft cabin or interior noise.

  14. Manual control displays for a four-dimensional landing approach

    NASA Technical Reports Server (NTRS)

    Silverthorn, J. T.; Swaim, R. L.

    1975-01-01

    Six instrument rated pilots flew a STOL fixed base simulator to study the effectiveness of three displays for a four dimensional approach. The three examined displays were a digital readout of forward position error, a digital speed command, and an analog display showing forward position error and error prediction. A flight director was used in all conditions. All test runs were for a typical four dimensional approach in moderate turbulence that included a change in commanded ground speed, a change in flight path angle, and two standard rate sixty degree turns. Use of the digital forward position error display resulted in large overshoot in the forward position error. Some type of lead (rate or prediction information) was shown to be needed. The best overall performance was obtained using the speed command display. It was demonstrated that curved approaches can be flown with relative ease.

  15. A Decision-Theoretic Approach to Autonomous Planetary Rover Control

    NASA Technical Reports Server (NTRS)

    Zilberstein, Shlomo

    2004-01-01

    The report discusses the: Decentralized Control of Markov Decision Processes. Study the complexity of decentralized control of Markov decision processes, and develop algorithms for finding optimal control policies. Scheduling Contract Algorithms. Develop an optimal method for scheduling runs of a contract anytime algorithm (one that takes the deadline as input) in situations where the deadline is unknown, multiple problem instances must be solved, and a multi-processor machine is available. Planetary Rover Control as a Markov Decision Process.Use the Markov decision process framework to formalize and solve problems in planetary rover control. Adaptive Peer Selection. Use reinforcement learning to maximize the expected down-load speed for a client in a peer-to-peer file sharing system.

  16. Individual Differences in Approach and Avoidance Inclinations Moderate the Effect of Self-Control Depletion on Ad-Lib Drinking

    PubMed Central

    Schlauch, Robert C.; Christensen, Rita L.; Derrick, Jaye L.; Crane, Cory A.; Collins, R. Lorraine

    2015-01-01

    Background The current study sought to examine how exerting self-control to inhibit stereotype use affects alcohol consumption. In addition, we sought to expand previous findings via examination of how individual differences in motivations to approach or avoid alcohol consumption interact with self-control depletion to determine the regulation of ad-lib drinking behavior. Methods Sixty-one social drinkers (31 female) were recruited to participate in a socially relevant self-control depletion task in which they were randomly assigned to one of two creative writing conditions: 1) the self-control depletion condition with explicit instructions to refrain from using stereotypes, or 2) the non-depletion condition in which no instructions were given regarding the use of stereotypes. Participants then completed an ad-lib drinking task and self-report questionnaires pertaining to their motivation to consume alcohol. Results As predicted, results indicated a significant three-way interaction between depletion condition, approach inclinations, and avoidance inclinations. Specifically, self-control depletion predicted greater drinking disinhibition (i.e., mean sip size, total alcohol consumption) only among participants high in both approach and avoidance. Conclusions Taken together, results from the current study highlight the importance of both approach and avoidance inclinations in the failure to regulate alcohol consumption following a routine, socially relevant form of self-control depletion. Our results also suggest that the high approach / high avoidance motivational profile may predict the greatest risk among those actively trying to regulate their drinking. PMID:26756800

  17. Successful emotion regulation is predicted by amygdala activity and aspects of personality: A latent variable approach.

    PubMed

    Morawetz, Carmen; Alexandrowicz, Rainer W; Heekeren, Hauke R

    2017-04-01

    The experience of emotions and their cognitive control are based upon neural responses in prefrontal and subcortical regions and could be affected by personality and temperamental traits. Previous studies established an association between activity in reappraisal-related brain regions (e.g., inferior frontal gyrus and amygdala) and emotion regulation success. Given these relationships, we aimed to further elucidate how individual differences in emotion regulation skills relate to brain activity within the emotion regulation network on the one hand, and personality/temperamental traits on the other. We directly examined the relationship between personality and temperamental traits, emotion regulation success and its underlying neuronal network in a large sample (N = 82) using an explicit emotion regulation task and functional MRI (fMRI). We applied a multimethodological analysis approach, combing standard activation-based analyses with structural equation modeling. First, we found that successful downregulation is predicted by activity in key regions related to emotion processing. Second, the individual ability to successfully upregulate emotions is strongly associated with the ability to identify feelings, conscientiousness, and neuroticism. Third, the successful downregulation of emotion is modulated by openness to experience and habitual use of reappraisal. Fourth, the ability to regulate emotions is best predicted by a combination of brain activity and personality as well temperamental traits. Using a multimethodological analysis approach, we provide a first step toward a causal model of individual differences in emotion regulation ability by linking biological systems underlying emotion regulation with descriptive constructs. (PsycINFO Database Record

  18. The aircraft energy efficiency active controls technology program

    NASA Technical Reports Server (NTRS)

    Hood, R. V., Jr.

    1977-01-01

    Broad outlines of the NASA Aircraft Energy Efficiency Program for expediting the application of active controls technology to civil transport aircraft are presented. Advances in propulsion and airframe technology to cut down on fuel consumption and fuel costs, a program for an energy-efficient transport, and integrated analysis and design technology in aerodynamics, structures, and active controls are envisaged. Fault-tolerant computer systems and fault-tolerant flight control system architectures are under study. Contracts with leading manufacturers for research and development work on wing-tip extensions and winglets for the B-747, a wing load alleviation system, elastic mode suppression, maneuver-load control, and gust alleviation are mentioned.

  19. A Verification-Driven Approach to Control Analysis and Tuning

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    This paper proposes a methodology for the analysis and tuning of controllers using control verification metrics. These metrics, which are introduced in a companion paper, measure the size of the largest uncertainty set of a given class for which the closed-loop specifications are satisfied. This framework integrates deterministic and probabilistic uncertainty models into a setting that enables the deformation of sets in the parameter space, the control design space, and in the union of these two spaces. In regard to control analysis, we propose strategies that enable bounding regions of the design space where the specifications are satisfied by all the closed-loop systems associated with a prescribed uncertainty set. When this is unfeasible, we bound regions where the probability of satisfying the requirements exceeds a prescribed value. In regard to control tuning, we propose strategies for the improvement of the robust characteristics of a baseline controller. Some of these strategies use multi-point approximations to the control verification metrics in order to alleviate the numerical burden of solving a min-max problem. Since this methodology targets non-linear systems having an arbitrary, possibly implicit, functional dependency on the uncertain parameters and for which high-fidelity simulations are available, they are applicable to realistic engineering problems..

  20. Active Feedback Control of a Web Flutter Using Flow Control Devices

    NASA Astrophysics Data System (ADS)

    Hayashi, Yusuke; Watanabe, Masahiro; Hara, Kensuke

    This paper develops a non-contact active feedback control of web flutter in a narrow passage by using movable plates set at inlet and outlet of the passage. The strategy of this active feedback control is based on the flow-control which cancels the exciting fluid force acting on the web, i.e., cancels the self-excited feedback mechanism. In this paper, suppression of the web flutter by the active feedback control is demonstrated experimentally. In the experiments, a web (film), as a controlled object, is subjected to air flow in a narrow passage. The web flutter occurs to the web in the translational motion over the critical flow velocity. And the web flutter is actively controlled and suppressed by the movable plate motion which changes the air flow in the passage. The critical flow velocity under controlled condition is examined with changing the controller gain and phase-shift between the web motion and the movable plate motion. As a result, it is indicated that the active feedback control increases the critical flow velocity, and suppress the web flutter effectively. Moreover, the control performance is examined experimentally, and stabilization mechanism by the active feedback control is discussed.

  1. Overview of magnetic bearing control and linearization approaches for annular magnetically suspended devices

    NASA Technical Reports Server (NTRS)

    Groom, N. J.

    1984-01-01

    An overview of magnetic bearing control and linearization approaches which have been considered for annular magnetically suspended devices is presented. These devices include the Annular Momentum Control Device and the Annular Suspension and Pointing System. Two approaches were investigated for controlling the magnetic actuator. One approach involves controlling the upper and lower electromagnets differentially about a bias flux. The bias flux can either be supplied by permanent magnets in the magnetic circuit or by bias currents. In the other approach, either the upper electromagnet or the lower electromagnet is controlled depending on the direction of force required. One advantage of the bias flux is that for small gap perturbations about a fixed operating point, the force-current characteristic is linear. Linearization approaches investigated for individual element control include an analog solution of the nonlinear electromagnet force equation and a microprocessor-based table lookup method.

  2. An Exploratory Simulator Study on the Use of Active Control Devices in Car Driving

    DTIC Science & Technology

    1992-05-04

    system to the driver and therefore concurrently serve as a proprioceptive -tactual display (RPihmann, 1981). The term "tactual" is used in the meaning of...displayed proprioceptive -tactual cues (see common coding approach in information processing, Prinz, 1990). The control loop for an active control...KlMckner & St6cker; 1990). In its present form the accelerator hardly pvrode- any systematic proprioceptive - tactual feedback to the driver abot.t the

  3. Adaptive Current Control Method for Hybrid Active Power Filter

    NASA Astrophysics Data System (ADS)

    Chau, Minh Thuyen

    2016-09-01

    This paper proposes an adaptive current control method for Hybrid Active Power Filter (HAPF). It consists of a fuzzy-neural controller, identification and prediction model and cost function. The fuzzy-neural controller parameters are adjusted according to the cost function minimum criteria. For this reason, the proposed control method has a capability on-line control clings to variation of the load harmonic currents. Compared to the single fuzzy logic control method, the proposed control method shows the advantages of better dynamic response, compensation error in steady-state is smaller, able to online control is better and harmonics cancelling is more effective. Simulation and experimental results have demonstrated the effectiveness of the proposed control method.

  4. Active tendon control of reinforced concrete frame structures subjected to near-fault effects

    NASA Astrophysics Data System (ADS)

    Nigdeli, Sinan Melih; Boduroǧlu, M. Hasan

    2013-10-01

    A reinforced concrete (RC) frame structure was controlled with active tendons under the excitation of near-fault ground motions. Proportional Integral Derivative (PID) type controllers were used and the controller was tuned by using a numerical algorithm. In order to prevent brittle fracture of the structure, the aim of the control is to reduce maximum base shear force. The RC structure was investigated for different characteristic strengths of concrete and the approach is applicable for the structure with 14 MPa concrete strength or higher.

  5. Developing a Systematic Corrosion Control Evaluation Approach in Flint

    EPA Science Inventory

    Presentation covers what the projects were that were recommended by the Flint Safe Drinking Water Task Force for corrosion control assessment for Flint, focusing on the sequential sampling project, the pipe rigs, and pipe scale analyses.

  6. Group Theoretical Approach for Controlled Quantum Mechanical Systems

    DTIC Science & Technology

    2007-11-06

    evolution equation with Hamiltonians which may possess discrete , continuous, and mixed spectrum. For such a quantum system, the Hamiltonian operator...study of classical linear and nonlinear systems, which proves to be very useful in understanding the design problems such as disturbance decoupling...developed by Kunita can then be implemented to establish controllability conditions for the original time-dependent Schrodinger control problem. The end

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  8. Active control of spectral detail radiated by an air-loaded impacted membrane

    NASA Astrophysics Data System (ADS)

    Rollow, J. Douglas, IV

    An active control system is developed to independently operate on the vibration of individual modes of an air-loaded drum head, resulting in changes in the acoustic field radiated from the structure. The timbre of the system is investigated, and techniques for changing the characteristic frequencies by means of the control system are proposed. A feedforward control system is constructed for empirical investigation of this approach, creating a musical instrument which can produce a variety of sounds not available with strictly mechanical systems. The work is motivated by applications for actively controlled structures, active control of sound quality, and musical acoustics. The instrument consists of a Mylar timpano head stretched over an enclosure which has been outfitted with electroacoustic drivers. Sensors are arranged on the surface of the drum head and combined to measure modal vibration, and the array of drivers allows independent control of these modes. A signal processor is used to form modal control filters which can modify the loading of each mode, changing the time-dependent and spectral characteristics, and therefore the timbre, of the radiated sound. A theoretical formulation of active control of structural vibration by means of fluid-coupled actuators is expressed, and computational solutions show the effects of fluid loading and the radiated field. Experimental results with the new instrument are shown, with implementations of the control system providing a demonstrated degree of control, and illustrating several limitations of such systems.

  9. Design approach for a microprogrammed control unit with built in self test

    SciTech Connect

    Duran, J.; Mangir, T.E.

    1983-10-01

    An architecture allowing concurrent self-testing of a microprogrammed control unit is presented and compared with other control unit testing strategies. This approach allows testing of the control unit independent of the operational section, minimizes the hardcore, and is easily incorporated in microprogrammed control units. Since testing is concurrent, the probability of detecting intermittent errors is high. VLSI implementations are feasible. 14 references.

  10. Evaluate fundamental approaches to longwall dust control. Phase III report

    SciTech Connect

    Babbitt, C.; Bartlett, P.; Kelly, J.; Ludlow, J.; Mangolds, A.; Rajan, S.; Ruggieri, S.; Varga, E.

    1984-03-31

    The overall objective of the contract is to evaluate the effectiveness of available dust control technology for double-drum shearer longwall sections in a coordinated, systematic program at a few longwall test sections and to make the results available to the entire coal mining industry. This program is investigating nine different dust control techniques. These nine subprograms encompass a broad range of dust control measures ranging from administrative controls to new hardware. They span not only presently employed methods but also those recently adopted in the United States and those proposed for the future. This report documents the Phase III effort on each of the subprograms. For clarity, the report is divided in sections by subprogram as follows: Section 2, Subprogram A - passive barriers/spray air movers for dust control; Section 3, Subprogram B - practical aspects of deep cutting; Section 4, Subprogram C - stage loader dust control; Section 5, Subprogram D - longwall automation technology; Section 6, Subprogram E - longwall application of ventilation curtains; Section 7, Subprogram F - reversed drum rotation; Section 8, Subprogram G - reduction of shield generated dust; Section 9, Subprogram H - air canopies for longwalls; and Section 10, Subprogram I - mining practices. 43 figures, 11 tables.

  11. Active sensing without efference copy: referent control of perception.

    PubMed

    Feldman, Anatol G

    2016-09-01

    Although action and perception are different behaviors, they are likely to be interrelated, as implied by the notions of perception-action coupling and active sensing. Traditionally, it has been assumed that the nervous system directly preprograms motor commands required for actions and uses a copy of them called efference copy (EC) to also influence our senses. This review offers a critical analysis of the EC concept by identifying its limitations. An alternative to the EC concept is based on the experimentally confirmed notion that sensory signals from receptors are perceived relative to referent signals specified by the brain. These referents also underlie the control of motor actions by predetermining where, in the spatial domain, muscles can work without preprogramming how they should work in terms of motor commands or EC. This approach helps solve several problems of action and explain several sensory experiences, including position sense and the sense that the world remains stationary despite changes in its retinal image during eye or body motion (visual space constancy). The phantom limb phenomenon and other kinesthetic illusions are also explained within this framework.

  12. Robust control design techniques for active flutter suppression

    NASA Technical Reports Server (NTRS)

    Ozbay, Hitay; Bachmann, Glen R.

    1994-01-01

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

  13. Mechanisms of active control for noise inside a vibrating cylinder

    NASA Technical Reports Server (NTRS)

    Lester, Harold C.; Fuller, Chris R.

    1987-01-01

    The active control of propeller-induced noise fields inside a flexible cylinder is studied with attention given to the noise reduction mechanisms inherent in the present coupled acoustic shell model. The active noise control model consists of an infinitely long aluminum cylinder with a radius of 0.4 m and a thickness of 0.001 m. Pressure maps are shown when the two external sources are driven in-phase at a frequency corresponding to Omega = 0.22.

  14. Novel reinforcement learning approach for difficult control problems

    NASA Astrophysics Data System (ADS)

    Becus, Georges A.; Thompson, Edward A.

    1997-09-01

    We review work conducted over the past several years and aimed at developing reinforcement learning architectures for solving difficult control problems and based on and inspired by associative control process (ACP) networks. We briefly review ACP networks able to reproduce many classical instrumental conditioning test results observed in animal research and to engage in real-time, closed-loop, goal-seeking interactions with their environment. Chronologically, our contributions include the ideally interfaced ACP network which is endowed with hierarchical, attention, and failure recognition interface mechanisms which greatly enhanced the capabilities of the original ACP network. When solving the cart-pole problem, it achieves 100 percent reliability and a reduction in training time similar to that of Baird and Klopf's modified ACP network and additionally an order of magnitude reduction in number of failures experienced for successful training. Next we introduced the command and control center/internal drive (Cid) architecture for artificial neural learning systems. It consists of a hierarchy of command and control centers governing motor selection networks. Internal drives, similar hunger, thirst, or reproduction in biological systems, are formed within the controller to facilitate learning. Efficiency, reliability, and adjustability of this architecture were demonstrated on the benchmark cart-pole control problem. A comparison with other artificial learning systems indicates that it learns over 100 times faster than Barto, et al's adaptive search element/adaptive critic element, experiencing less failures by more than an order of magnitude while capable of being fine-tuned by the user, on- line, for improved performance without additional training. Finally we present work in progress on a 'peaks and valleys' scheme which moves away from the one-dimensional learning mechanism currently found in Cid and shows promises in solving even more difficult learning control

  15. An Approach to Autonomous Control for Space Nuclear Power Systems

    SciTech Connect

    Wood, Richard Thomas; Upadhyaya, Belle R.

    2011-01-01

    Under Project Prometheus, the National Aeronautics and Space Administration (NASA) investigated deep space missions that would utilize space nuclear power systems (SNPSs) to provide energy for propulsion and spacecraft power. The initial study involved the Jupiter Icy Moons Orbiter (JIMO), which was proposed to conduct in-depth studies of three Jovian moons. Current radioisotope thermoelectric generator (RTG) and solar power systems cannot meet expected mission power demands, which include propulsion, scientific instrument packages, and communications. Historically, RTGs have provided long-lived, highly reliable, low-power-level systems. Solar power systems can provide much greater levels of power, but power density levels decrease dramatically at {approx} 1.5 astronomical units (AU) and beyond. Alternatively, an SNPS can supply high-sustained power for space applications that is both reliable and mass efficient. Terrestrial nuclear reactors employ varying degrees of human control and decision-making for operations and benefit from periodic human interaction for maintenance. In contrast, the control system of an SNPS must be able to provide continuous operatio for the mission duration with limited immediate human interaction and no opportunity for hardware maintenance or sensor calibration. In effect, the SNPS control system must be able to independently operate the power plant while maintaining power production even when subject to off-normal events and component failure. This capability is critical because it will not be possible to rely upon continuous, immediate human interaction for control due to communications delays and periods of planetary occlusion. In addition, uncertainties, rare events, and component degradation combine with the aforementioned inaccessibility and unattended operation to pose unique challenges that an SNPS control system must accommodate. Autonomous control is needed to address these challenges and optimize the reactor control design.

  16. Acoustic Aspects of Active-Twist Rotor Control

    NASA Technical Reports Server (NTRS)

    Booth, Earl R., Jr.; Wilbur, Matthew L.

    2002-01-01

    The use of an Active Twist Rotor system to provide both vibration reduction and performance enhancement has been explored in recent analytical and experimental studies. Effects of active-twist control on rotor noise, however, had not been determined. During a recent wind tunnel test of an active-twist rotor system, a set of acoustic measurements were obtained to assess the effects of active-twist control on noise produced by the rotor, especially blade-vortex interaction (BVI) noise. It was found that for rotor operating conditions where BVI noise is dominant, active-twist control provided a reduction in BVI noise level. This BVI noise reduction was almost, but not quite, as large as that obtained in a similar test using HHC. However, vibration levels were usually adversely affected at operating conditions favoring minimum BVI noise. Conversely, operating conditions favoring minimum vibration levels affected BVI noise levels, but not always adversely.

  17. Controlling neural activity in Caenorhabditis elegans to evoke chemotactic behavior

    NASA Astrophysics Data System (ADS)

    Kocabas, Askin; Shen, Ching-Han; Guo, Zengcai V.; Ramanathan, Sharad

    2013-03-01

    Animals locate and track chemoattractive gradients in the environment to find food. With its simple nervous system, Caenorhabditis elegans is a good model system in which to understand how the dynamics of neural activity control this search behavior. To understand how the activity in its interneurons coordinate different motor programs to lead the animal to food, here we used optogenetics and new optical tools to manipulate neural activity directly in freely moving animals to evoke chemotactic behavior. By deducing the classes of activity patterns triggered during chemotaxis and exciting individual neurons with these patterns, we identified interneurons that control the essential locomotory programs for this behavior. Notably, we discovered that controlling the dynamics of activity in just one interneuron pair was sufficient to force the animal to locate, turn towards and track virtual light gradients.

  18. Broadly neutralizing antibodies: An approach to control HIV-1 infection.

    PubMed

    Yaseen, Mahmoud Mohammad; Yaseen, Mohammad Mahmoud; Alqudah, Mohammad Ali

    2017-01-02

    Although available antiretroviral therapy (ART) has changed human immunodeficiency virus (HIV)-1 infection to a non-fatal chronic disease, the economic burden of lifelong therapy, severe adverse ART effects, daily ART adherence, and emergence of ART-resistant HIV-1 mutants require prospecting for alternative therapeutic modalities. Indeed, a growing body of evidence suggests that broadly neutralizing anti-HIV-1 antibodies (BNAbs) may offer one such feasible alternative. To evaluate their therapeutic potential in established HIV-1 infection, we sought to address recent advances in pre-clinical and clinical investigations in this area of HIV-1 research. In addition, we addressed the obstacles that may impede the success of such immunotherapeutic approach, suggested strategic solutions, and briefly compared this approach with the currently used ART to open new insights for potential future passive immunotherapy for HIV-1 infection.

  19. Target-classification approach applied to active UXO sites

    NASA Astrophysics Data System (ADS)

    Shubitidze, F.; Fernández, J. P.; Shamatava, Irma; Barrowes, B. E.; O'Neill, K.

    2013-06-01

    This study is designed to illustrate the discrimination performance at two UXO active sites (Oklahoma's Fort Sill and the Massachusetts Military Reservation) of a set of advanced electromagnetic induction (EMI) inversion/discrimination models which include the orthonormalized volume magnetic source (ONVMS), joint diagonalization (JD), and differential evolution (DE) approaches and whose power and flexibility greatly exceed those of the simple dipole model. The Fort Sill site is highly contaminated by a mix of the following types of munitions: 37-mm target practice tracers, 60-mm illumination mortars, 75-mm and 4.5'' projectiles, 3.5'', 2.36'', and LAAW rockets, antitank mine fuzes with and without hex nuts, practice MK2 and M67 grenades, 2.5'' ballistic windshields, M2A1-mines with/without bases, M19-14 time fuzes, and 40-mm practice grenades with/without cartridges. The site at the MMR site contains targets of yet different sizes. In this work we apply our models to EMI data collected using the MetalMapper (MM) and 2 × 2 TEMTADS sensors. The data for each anomaly are inverted to extract estimates of the extrinsic and intrinsic parameters associated with each buried target. (The latter include the total volume magnetic source or NVMS, which relates to size, shape, and material properties; the former includes location, depth, and orientation). The estimated intrinsic parameters are then used for classification performed via library matching and the use of statistical classification algorithms; this process yielded prioritized dig-lists that were submitted to the Institute for Defense Analyses (IDA) for independent scoring. The models' classification performance is illustrated and assessed based on these independent evaluations.

  20. A Gradient Optimization Approach to Adaptive Multi-Robot Control

    DTIC Science & Technology

    2009-09-01

    optimization through the evolution of a dynamical system. Some existing approaches do not fit under the framework we propose in this chap- ter. A...parameters are coupled among robots, we must consider the evolution of all the robots’ parameters together. Let = [ a]. (4.39) be a concatenated...dynamics * Synchronous evolution of equa- tions * Exact Voronoi cells computed from exact positions of all Voronoi neighbors * Exact integrals over

  1. Immunotherapeutic Approaches for the Control and Eradication of HIV.

    PubMed

    Amsterdam, Daniel

    2015-01-01

    Since the onset of the AIDS epidemic over 35 years ago, attempts at immunologic manipulation to develop preventative and therapeutic approaches to HIV infection have been the subject of intense focus by the scientific community. New tactics such as latency reveal agents and immune interventions with engineered and directed monoclonal antibodies, as well as vaccines for prevention and treatment are among the strategies addressed in this review.

  2. An active attitude control system for a drag sail satellite

    NASA Astrophysics Data System (ADS)

    Steyn, Willem Herman; Jordaan, Hendrik Willem

    2016-11-01

    The paper describes the development and simulation results of a full ADCS subsystem for the deOrbitSail drag sail mission. The deOrbitSail satellite was developed as part of an European FP7 collaboration research project. The satellite was launched and commissioning started on 10th July 2015. Various new actuators and sensors designed for this mission will be presented. The deOrbitSail satellite is a 3U CubeSat to deploy a 4 by 4 m drag sail from an initial 650 km circular polar low earth orbit. With an active attitude control system it will be shown that by maximising the drag force, the expected de-orbiting period from the initial altitude will be less than 50 days. A future application of this technology will be the use of small drag sails as low-cost devices to de-orbit LEO satellites, when they have reached their end of life, without having to use expensive propulsion systems. Simulation and Hardware-in-Loop experiments proved the feasibility of the proposed attitude control system. A magnetic-only control approach using a Y-Thomson spin, is used to detumble the 3U Cubesat with stowed sail and subsequently to 3-axis stabilise the satellite to be ready for the final deployment phase. Minituarised torquer rods, a nano-sized momentum wheel, attitude sensor hardware (magnetometer, sun, earth) developed for this phase will be presented. The final phase will be to deploy and 3-axis stabilise the drag sail normal to the satellite's velocity vector, using a combined Y-momentum wheel and magnetic controller. The design and performance improvements when using a 2-axis translation stage to adjust the sail centre-of-pressure to satellite centre-of-mass offset, will also be discussed, although for launch risk reasons this stage was not included in the final flight configuration. To accurately determine the drag sail's attitude during the sunlit part of the orbit, an accurate wide field of view dual sensor to measure both the sun and nadir vector direction was developed for

  3. Literature-Based vrs. Controlled-Vocabulary Approach for Beginning Readers

    ERIC Educational Resources Information Center

    Soiferman, L. Karen

    2016-01-01

    The best method for teaching children how to read has been debated for decades. The two major approaches have been the vocabulary controlled approach (phonics), and the literature based approach which uses children's literature to teach reading. There are proponents for both methodologies. The literature on the issue is as varied as the authors…

  4. Targeting Fear of Spiders with Control-, Acceptance-, and Information-Based Approaches

    ERIC Educational Resources Information Center

    Wagener, Alexandra L.; Zettle, Robert D.

    2011-01-01

    The relative impact of control-, acceptance-, and information-based approaches in targeting a midlevel fear of spiders among college students was evaluated. Participants listened to a brief protocol presenting one of the three approaches before completing the Perceived-Threat Behavioral Approach Test (PT-BAT; Cochrane, Barnes-Holmes, &…

  5. Cognitive control in majority search: a computational modeling approach.

    PubMed

    Wang, Hongbin; Liu, Xun; Fan, Jin

    2011-01-01

    Despite the importance of cognitive control in many cognitive tasks involving uncertainty, the computational mechanisms of cognitive control in response to uncertainty remain unclear. In this study, we develop biologically realistic neural network models to investigate the instantiation of cognitive control in a majority function task, where one determines the category to which the majority of items in a group belong. Two models are constructed, both of which include the same set of modules representing task-relevant brain functions and share the same model structure. However, with a critical change of a model parameter setting, the two models implement two different underlying algorithms: one for grouping search (where a subgroup of items are sampled and re-sampled until a congruent sample is found) and the other for self-terminating search (where the items are scanned and counted one-by-one until the majority is decided). The two algorithms hold distinct implications for the involvement of cognitive control. The modeling results show that while both models are able to perform the task, the grouping search model fit the human data better than the self-terminating search model. An examination of the dynamics underlying model performance reveals how cognitive control might be instantiated in the brain for computing the majority function.

  6. State feedback control of switched linear systems: An LMI approach

    NASA Astrophysics Data System (ADS)

    Montagner, V. F.; Leite, V. J. S.; Oliveira, R. C. L. F.; Peres, P. L. D.

    2006-10-01

    This paper addresses the problem of state feedback control of continuous-time switched linear systems with arbitrary switching rules. A quadratic Lyapunov function with a common matrix is used to derive a stabilizing switching control strategy that guarantees: (i) the assignment of all the eigenvalues of each linear subsystem inside a chosen circle in the left-hand half of the complex plane; (ii) a minimum disturbance attenuation level for the closed-loop switched system. The proposed design conditions are given in terms of linear matrix inequalities that encompass previous results based on quadratic stability conditions with fixed control gains. Although the quadratic stability based on a fixed Lyapunov matrix has been widely used in robust control design, the use of this condition to provide a convex design method for switching feedback gains has not been fully investigated. Numerical examples show that the switching control strategy can cope with more stringent design specifications than the fixed gain strategy, being useful to improve the performance of this class of systems.

  7. A combined PLC and CPU approach to multiprocessor control

    SciTech Connect

    Harris, J.J.; Broesch, J.D.; Coon, R.M.

    1995-10-01

    A sophisticated multiprocessor control system has been developed for use in the E-Power Supply System Integrated Control (EPSSIC) on the DIII-D tokamak. EPSSIC provides control and interlocks for the ohmic heating coil power supply and its associated systems. Of particular interest is the architecture of this system: both a Programmable Logic Controller (PLC) and a Central Processor Unit (CPU) have been combined on a standard VME bus. The PLC and CPU input and output signals are routed through signal conditioning modules, which provide the necessary voltage and ground isolation. Additionally these modules adapt the signal levels to that of the VME I/O boards. One set of I/O signals is shared between the two processors. The resulting multiprocessor system provides a number of advantages: redundant operation for mission critical situations, flexible communications using conventional TCP/IP protocols, the simplicity of ladder logic programming for the majority of the control code, and an easily maintained and expandable non-proprietary system.

  8. Cognitive Control in Majority Search: A Computational Modeling Approach

    PubMed Central

    Wang, Hongbin; Liu, Xun; Fan, Jin

    2011-01-01

    Despite the importance of cognitive control in many cognitive tasks involving uncertainty, the computational mechanisms of cognitive control in response to uncertainty remain unclear. In this study, we develop biologically realistic neural network models to investigate the instantiation of cognitive control in a majority function task, where one determines the category to which the majority of items in a group belong. Two models are constructed, both of which include the same set of modules representing task-relevant brain functions and share the same model structure. However, with a critical change of a model parameter setting, the two models implement two different underlying algorithms: one for grouping search (where a subgroup of items are sampled and re-sampled until a congruent sample is found) and the other for self-terminating search (where the items are scanned and counted one-by-one until the majority is decided). The two algorithms hold distinct implications for the involvement of cognitive control. The modeling results show that while both models are able to perform the task, the grouping search model fit the human data better than the self-terminating search model. An examination of the dynamics underlying model performance reveals how cognitive control might be instantiated in the brain for computing the majority function. PMID:21369357

  9. ACOSS FIVE (Active Control of Space Structures). Phase 1A

    DTIC Science & Technology

    1982-03-01

    massive rigid body in its center. The beam is suspended to allow only rotations (or bending) in the horizontal plane. Actuators mounted on the ground...and 2-axes. However, because the laser assembly is very massive (lead weights were added to balance the laser and increase the rotational inertia...output ( MIMO ) systems, the usual approach is to decompose them into separate SISO control systems and synthesize controllers for them individually

  10. A geometric approach to quantum control in projective hilbert spaces

    NASA Astrophysics Data System (ADS)

    Pastorello, Davide

    2017-02-01

    A quantum theory in a finite-dimensional Hilbert space can be formulated as a proper geometric Hamiltonian theory as explained in [2, 3, 7, 9]. From this point of view a quantum system can be described within a classical-like framework where quantum dynamics is represented by a Hamiltonian flow in the phase space given by a projective Hilbert space. This paper is devoted to investigating how the notion of an accessibility algebra from classical control theory can be applied within the geometric Hamiltonian formulation of quantum mechanics to study controllability of a quantum system. A new characterization of quantum controllability in terms of Killing vector fields w.r.t. the Fubini-Study metric on projective space is also discussed.

  11. Bioengineered probiotics, a strategic approach to control enteric infections.

    PubMed

    Amalaradjou, Mary Anne Roshni; Bhunia, Arun K

    2013-01-01

    Enteric infections account for high morbidity and mortality and are considered to be the fifth leading cause of death at all ages worldwide. Seventy percent of all enteric infections are foodborne. Thus significant efforts have been directed toward the detection, control and prevention of foodborne diseases. Many antimicrobials including antibiotics have been used for their control and prevention. However, probiotics offer a potential alternative intervention strategy owing to their general health beneficial properties and inhibitory effects against foodborne pathogens. Often, antimicrobial probiotic action is non-specific and non-discriminatory or may be ineffective. In such cases, bioengineered probiotics expressing foreign gene products to achieve specific function is highly desirable. In this review we summarize the strategic development of recombinant bioengineered probiotics to control enteric infections, and to examine how scientific advancements in the human microbiome and their immunomodulatory effects help develop such novel and safe bioengineered probiotics.

  12. Bioengineered probiotics, a strategic approach to control enteric infections

    PubMed Central

    Amalaradjou, Mary Anne Roshni; Bhunia, Arun K

    2013-01-01

    Enteric infections account for high morbidity and mortality and are considered to be the fifth leading cause of death at all ages worldwide. Seventy percent of all enteric infections are foodborne. Thus significant efforts have been directed toward the detection, control and prevention of foodborne diseases. Many antimicrobials including antibiotics have been used for their control and prevention. However, probiotics offer a potential alternative intervention strategy owing to their general health beneficial properties and inhibitory effects against foodborne pathogens. Often, antimicrobial probiotic action is non-specific and non-discriminatory or may be ineffective. In such cases, bioengineered probiotics expressing foreign gene products to achieve specific function is highly desirable. In this review we summarize the strategic development of recombinant bioengineered probiotics to control enteric infections, and to examine how scientific advancements in the human microbiome and their immunomodulatory effects help develop such novel and safe bioengineered probiotics. PMID:23327986

  13. A human factors approach to range scheduling for satellite control

    NASA Technical Reports Server (NTRS)

    Wright, Cameron H. G.; Aitken, Donald J.

    1991-01-01

    Range scheduling for satellite control presents a classical problem: supervisory control of a large-scale dynamic system, with unwieldy amounts of interrelated data used as inputs to the decision process. Increased automation of the task, with the appropriate human-computer interface, is highly desirable. The development and user evaluation of a semi-automated network range scheduling system is described. The system incorporates a synergistic human-computer interface consisting of a large screen color display, voice input/output, a 'sonic pen' pointing device, a touchscreen color CRT, and a standard keyboard. From a human factors standpoint, this development represents the first major improvement in almost 30 years to the satellite control network scheduling task.

  14. Active control of multi-dimensional random sound in ducts

    NASA Technical Reports Server (NTRS)

    Silcox, R. J.; Elliott, S. J.

    1990-01-01

    Previous work has demonstrated how active control may be applied to the control of random noise in ducts. These implementations, however, have been restricted to frequencies where only plane waves are propagating in the duct. In spite of this, the need for this technology at low frequencies has progressed to the point where commercial products that apply these concepts are currently available. Extending the frequency range of this technology requires the extension of current single channel controllers to multi-variate control systems as well as addressing the problems inherent in controlling higher order modes. The application of active control in the multi-dimensional propagation of random noise in waveguides is examined. An adaptive system is implemented using measured system frequency response functions. Experimental results are presented illustrating attained suppressions of 15 to 30 dB for random noise propagating in multiple modes.

  15. Active flutter suppression using optical output feedback digital controllers

    NASA Technical Reports Server (NTRS)

    1982-01-01

    A method for synthesizing digital active flutter suppression controllers using the concept of optimal output feedback is presented. A convergent algorithm is employed to determine constrained control law parameters that minimize an infinite time discrete quadratic performance index. Low order compensator dynamics are included in the control law and the compensator parameters are computed along with the output feedback gain as part of the optimization process. An input noise adjustment procedure is used to improve the stability margins of the digital active flutter controller. Sample rate variation, prefilter pole variation, control structure variation and gain scheduling are discussed. A digital control law which accommodates computation delay can stabilize the wing with reasonable rms performance and adequate stability margins.

  16. Feedforward control of sound transmission using an active acoustic metamaterial

    NASA Astrophysics Data System (ADS)

    Cheer, Jordan; Daley, Stephen; McCormick, Cameron

    2017-02-01

    Metamaterials have received significant interest in recent years due to their potential ability to exhibit behaviour not found in naturally occurring materials. This includes the generation of band gaps, which are frequency regions with high levels of wave attenuation. In the context of acoustics, these band gaps can be tuned to occur at low frequencies where the acoustic wavelength is large compared to the material, and where the performance of traditional passive noise control treatments is limited. Therefore, such acoustic metamaterials have been shown to offer a significant performance advantage compared to traditional passive control treatments, however, due to their resonant behaviour, the band gaps tend to occur over a relatively narrow frequency range. A similar long wavelength performance advantage can be achieved using active noise control, but the systems in this case do not rely on resonant behaviour. This paper demonstrates how the performance of an acoustic metamaterial, consisting of an array of Helmholtz resonators, can be significantly enhanced by the integration of an active control mechanism that is facilitated by embedding loudspeakers into the resonators. Crucially, it is then also shown how the active acoustic metamaterial significantly outperforms an equivalent traditional active noise control system. In both cases a broadband feedforward control strategy is employed to minimise the transmitted pressure in a one-dimensional acoustic control problem and a new method of weighting the control effort over a targeted frequency range is described.

  17. Advanced aerodynamics and active controls. Selected NASA research

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Aerodynamic and active control concepts for application to commercial transport aircraft are discussed. Selected topics include in flight direct strike lightning research, triply redundant digital fly by wire control systems, tail configurations, winglets, and the drones for aerodynamic and structural testing (DAST) program.

  18. Applications of active adaptive noise control to jet engines

    NASA Technical Reports Server (NTRS)

    Shoureshi, Rahmat; Brackney, Larry

    1993-01-01

    During phase 2 research on the application of active noise control to jet engines, the development of multiple-input/multiple-output (MIMO) active adaptive noise control algorithms and acoustic/controls models for turbofan engines were considered. Specific goals for this research phase included: (1) implementation of a MIMO adaptive minimum variance active noise controller; and (2) turbofan engine model development. A minimum variance control law for adaptive active noise control has been developed, simulated, and implemented for single-input/single-output (SISO) systems. Since acoustic systems tend to be distributed, multiple sensors, and actuators are more appropriate. As such, the SISO minimum variance controller was extended to the MIMO case. Simulation and experimental results are presented. A state-space model of a simplified gas turbine engine is developed using the bond graph technique. The model retains important system behavior, yet is of low enough order to be useful for controller design. Expansion of the model to include multiple stages and spools is also discussed.

  19. Electromechanical Simulation of Actively Controlled Rotordynamic Systems with Piezoelectric Actuators

    NASA Technical Reports Server (NTRS)

    Lin, Reng Rong; Palazzolo, A. B.; Kascak, A. F.; Montague, G.

    1991-01-01

    Theories and tests for incorporating piezoelectric pushers as actuator devices for active vibration control are discussed. It started from a simple model with the assumption of ideal pusher characteristics and progressed to electromechanical models with nonideal pushers. Effects on system stability due to the nonideal characteristics of piezoelectric pushers and other elements in the control loop were investigated.

  20. Active Flow Control Strategies Using Surface Pressure Measurements

    NASA Technical Reports Server (NTRS)

    Kumar, Vikas; Alvi, Farrukh S.

    2010-01-01

    Evaluate the efficacy of Microjets Can we eliminate/minimize flow separation? Is the flow unsteadiness reduced? Guidelines for an active control Search for an appropriate sensor. Examine for means to develop a flow model for identifying the state of flow over the surface Guidelines toward future development of a Simple and Robust control methodology