Science.gov

Sample records for current error control

  1. GCF HSD error control

    NASA Technical Reports Server (NTRS)

    Hung, C. K.

    1978-01-01

    A selective repeat automatic repeat request (ARQ) system was implemented under software control in the Ground Communications Facility error detection and correction (EDC) assembly at JPL and the comm monitor and formatter (CMF) assembly at the DSSs. The CMF and EDC significantly improved real time data quality and significantly reduced the post-pass time required for replay of blocks originally received in error. Since the remote mission operation centers (RMOCs) do not provide compatible error correction equipment, error correction will not be used on the RMOC-JPL high speed data (HSD) circuits. The real time error correction capability will correct error burst or outage of two loop-times or less for each DSS-JPL HSD circuit.

  2. Aircraft system modeling error and control error

    NASA Technical Reports Server (NTRS)

    Kulkarni, Nilesh V. (Inventor); Kaneshige, John T. (Inventor); Krishnakumar, Kalmanje S. (Inventor); Burken, John J. (Inventor)

    2012-01-01

    A method for modeling error-driven adaptive control of an aircraft. Normal aircraft plant dynamics is modeled, using an original plant description in which a controller responds to a tracking error e(k) to drive the component to a normal reference value according to an asymptote curve. Where the system senses that (1) at least one aircraft plant component is experiencing an excursion and (2) the return of this component value toward its reference value is not proceeding according to the expected controller characteristics, neural network (NN) modeling of aircraft plant operation may be changed. However, if (1) is satisfied but the error component is returning toward its reference value according to expected controller characteristics, the NN will continue to model operation of the aircraft plant according to an original description.

  3. Control by model error estimation

    NASA Technical Reports Server (NTRS)

    Likins, P. W.; Skelton, R. E.

    1976-01-01

    Modern control theory relies upon the fidelity of the mathematical model of the system. Truncated modes, external disturbances, and parameter errors in linear system models are corrected by augmenting to the original system of equations an 'error system' which is designed to approximate the effects of such model errors. A Chebyshev error system is developed for application to the Large Space Telescope (LST).

  4. Retransmission error control with memory

    NASA Technical Reports Server (NTRS)

    Sindhu, P. S.

    1977-01-01

    In this paper, an error control technique that is a basic improvement over automatic-repeat-request ARQ is presented. Erroneously received blocks in an ARQ system are used for error control. The technique is termed ARQ-with-memory (MRQ). The general MRQ system is described, and simple upper and lower bounds are derived on the throughput achievable by MRQ. The performance of MRQ with respect to throughput, message delay and probability of error is compared to that of ARQ by simulating both systems using error data from a VHF satellite channel being operated in the ALOHA packet broadcasting mode.

  5. Errorless and errorful learning modulated by transcranial direct current stimulation

    PubMed Central

    2011-01-01

    Background Errorless learning is advantageous over trial and error learning (errorful learning) as errors are avoided during learning resulting in increased memory performance. Errorful learning challenges the executive control system of memory processes as the erroneous items compete with the correct items during retrieval. The left dorsolateral prefrontal cortex (DLPFC) is a core region involved in this executive control system. Transcranial direct current stimulation (tDCS) can modify the excitability of underlying brain functioning. Results In a single blinded tDCS study one group of young healthy participants received anodal and another group cathodal tDCS of the left DLPFC each compared to sham stimulation. Participants had to learn words in an errorless and an errorful manner using a word stem completion paradigm. The results showed that errorless compared to errorful learning had a profound effect on the memory performance in terms of quality. Anodal stimulation of the left DLPFC did not modulate the memory performance following errorless or errorful learning. By contrast, cathodal stimulation hampered memory performance after errorful learning compared to sham, whereas there was no modulation after errorless learning. Conclusions Concluding, the study further supports the advantages of errorless learning over errorful learning. Moreover, cathodal stimulation of the left DLPFC hampered memory performance following the conflict-inducing errorful learning as compared to no modulation after errorless learning emphasizing the importance of the left DLPFC in executive control of memory. PMID:21781298

  6. Superconducting fault current controller/current controller

    DOEpatents

    Cha, Yung S.

    2004-06-15

    A superconducting fault current controller/current controller employs a superconducting-shielded core reactor (SSCR) with a variable impedance in a secondary circuit to control current in a primary circuit such as an electrical distribution system. In a second embodiment, a variable current source is employed in a secondary circuit of an SSCR to control current in the primary circuit. In a third embodiment, both a variable impedance in one secondary circuit and a variable current source in a second circuit of an SSCR are employed for separate and independent control of current in the primary circuit.

  7. Automatic-repeat-request error control schemes

    NASA Technical Reports Server (NTRS)

    Lin, S.; Costello, D. J., Jr.; Miller, M. J.

    1983-01-01

    Error detection incorporated with automatic-repeat-request (ARQ) is widely used for error control in data communication systems. This method of error control is simple and provides high system reliability. If a properly chosen code is used for error detection, virtually error-free data transmission can be attained. Various types of ARQ and hybrid ARQ schemes, and error detection using linear block codes are surveyed.

  8. A cascaded coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Kasami, T.; Lin, S.

    1985-01-01

    A cascaded coding scheme for error control was investigated. The scheme employs a combination of hard and soft decisions in decoding. Error performance is analyzed. If the inner and outer codes are chosen properly, extremely high reliability can be attained even for a high channel bit-error-rate. Some example schemes are studied which seem to be quite suitable for satellite down-link error control.

  9. A cascaded coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Shu, L.; Kasami, T.

    1985-01-01

    A cascade coding scheme for error control is investigated. The scheme employs a combination of hard and soft decisions in decoding. Error performance is analyzed. If the inner and outer codes are chosen properly, extremely high reliability can be attained even for a high channel bit-error-rate. Some example schemes are evaluated. They seem to be quite suitable for satellite down-link error control.

  10. A concatenated coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Kasami, T.; Fujiwara, T.; Lin, S.

    1986-01-01

    In this paper, a concatenated coding scheme for error control in data communications is presented and analyzed. In this scheme, the inner code is used for both error correction and detection; however, the outer code is used only for error detection. A retransmission is requested if either the inner code decoder fails to make a successful decoding or the outer code decoder detects the presence of errors after the inner code decoding. Probability of undetected error (or decoding error) of the proposed scheme is derived. An efficient method for computing this probability is presented. Throughput efficiency of the proposed error control scheme incorporated with a selective-repeat ARQ retransmission strategy is also analyzed. Three specific examples are presented. One of the examples is proposed for error control in the NASA Telecommand System.

  11. A concatenated coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Kasami, T.; Fujiwara, T.; Lin, S.

    1986-01-01

    In this paper, a concatenated coding scheme for error control in data communications is presented and analyzed. In this scheme, the inner code is used for both error correction and detection; however, the outer code is used only for error detection. A retransmission is requested if either the inner code decoder fails to make a successful decoding or the outer code decoder detects the presence of errors after the inner code decoding. Probability of undetected error (or decoding error) of the proposed scheme is derived. An efficient method for computing this probability is presented. Throughput efficiency of the proposed error control scheme incorporated with a selective-repeat ARQ retransmission strategy is also analyzed. Three specific examples are presented. One of the examples is proposed for error control in the NASA Telecommand System.

  12. A concatenated coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Lin, S.

    1985-01-01

    A concatenated coding scheme for error contol in data communications was analyzed. The inner code is used for both error correction and detection, however the outer code is used only for error detection. A retransmission is requested if either the inner code decoder fails to make a successful decoding or the outer code decoder detects the presence of errors after the inner code decoding. Probability of undetected error of the proposed scheme is derived. An efficient method for computing this probability is presented. Throughout efficiency of the proposed error control scheme incorporated with a selective repeat ARQ retransmission strategy is analyzed.

  13. RHIC INSERTION REGION, SHUNT POWER SUPPLY CURRENT ERRORS.

    SciTech Connect

    BRUNO,D.; GANETIS,G.; LAMBIASE,R.F.; SANDBERG,J.

    2001-06-18

    The Relativistic Heavy Ion Collider (RHIC) was commissioned in 1999 and 2000. RHIC requires power supplies to supply currents to highly inductive superconducting magnets. The RHIC Insertion Region contain's many shunt power supplies to trim the current of different magnet elements in a large superconducting magnet circuit. Power Supply current error measurements were performed during the commissioning of RHIC. Models of these power supply systems were produced to predict and improve these power supply current errors using the circuit analysis program MicroCap V by Spectrum Software (TM). Results of the power supply current errors are presented from the models and from the measurements performed during the commissioning of RHIC.

  14. Metering error quantification under voltage and current waveform distortion

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Wang, Jia; Xie, Zhi; Zhang, Ran

    2017-09-01

    With integration of more and more renewable energies and distortion loads into power grid, the voltage and current waveform distortion results in metering error in the smart meters. Because of the negative effects on the metering accuracy and fairness, it is an important subject to study energy metering combined error. In this paper, after the comparing between metering theoretical value and real recorded value under different meter modes for linear and nonlinear loads, a quantification method of metering mode error is proposed under waveform distortion. Based on the metering and time-division multiplier principles, a quantification method of metering accuracy error is proposed also. Analyzing the mode error and accuracy error, a comprehensive error analysis method is presented which is suitable for new energy and nonlinear loads. The proposed method has been proved by simulation.

  15. Effects of errors on decoupled control systems

    NASA Technical Reports Server (NTRS)

    Hamer, H. A.; Johnson, K. G.

    1978-01-01

    Various error sources in a decoupled control system are considered in connection with longitudinal control on a simulated externally blown jet-flap STOL aircraft. The system employed the throttle, horizontal tail, and flaps to decouple the forward velocity, pitch angle, and flight-path angle. The errors considered were: (1) imperfect knowledge of airplane aerodynamic and control characteristics; (2) imperfect measurements of airplane state variables; (3) change in flight conditions, and (4) lag in the airplane controls and in engine response. The effects of the various errors on the decoupling process were generally minor. Significant coupling in flight-path angle was caused by control lag during speed-command maneuvers. However, this coupling could be eliminated by including the control lag in the design of the decoupled system. Other error sources affected primarily the commanded response quantity.

  16. Linearization of Attitude-Control Error Dynamics

    NASA Technical Reports Server (NTRS)

    Bach, Ralph; Paielli, Russell

    1993-01-01

    Direction cosines and quaternions are useful for representing rigid-body attitude because they exhibit no kinematic singularities. Each utilizes more variables than the minimum three degrees of freedom required to specify attitude. Therefore, application of a nonlinear inversion procedure to either formulation introduces singularities. Furthermore, in designing an attitude-control system, it is not appropriate to express attitude error as a difference of direction cosines (or quaternions). One should employ a measure of attitude error that not only is minimal but preserves orthogonal rotation properties as well. This note applies an inversion procedure to an appropriate measure of attitude error, so that the singularity occurs when the error reaches +/- 180 deg. This approach leads to the realization of a new model-follower attitude-control system that exhibits exact linear attitude-error dynamics.

  17. Linearization of Attitude-Control Error Dynamics

    NASA Technical Reports Server (NTRS)

    Bach, Ralph; Paielli, Russell

    1993-01-01

    Direction cosines and quaternions are useful for representing rigid-body attitude because they exhibit no kinematic singularities. Each utilizes more variables than the minimum three degrees of freedom required to specify attitude. Therefore, application of a nonlinear inversion procedure to either formulation introduces singularities. Furthermore, in designing an attitude-control system, it is not appropriate to express attitude error as a difference of direction cosines (or quaternions). One should employ a measure of attitude error that not only is minimal but preserves orthogonal rotation properties as well. This note applies an inversion procedure to an appropriate measure of attitude error, so that the singularity occurs when the error reaches +/- 180 deg. This approach leads to the realization of a new model-follower attitude-control system that exhibits exact linear attitude-error dynamics.

  18. Error types and error positions in neglect dyslexia: comparative analyses in neglect patients and healthy controls.

    PubMed

    Weinzierl, Christiane; Kerkhoff, Georg; van Eimeren, Lucia; Keller, Ingo; Stenneken, Prisca

    2012-10-01

    Unilateral spatial neglect frequently involves a lateralised reading disorder, neglect dyslexia (ND). Reading of single words in ND is characterised by left-sided omissions and substitutions of letters. However, it is unclear whether the distribution of error types and positions within a word shows a unique pattern of ND when directly compared to healthy controls. This question has been difficult to answer so far, given the usually low number of reading errors in healthy controls. Therefore, the present study compared single word reading of 18 patients with left-sided neglect, due to right-hemisphere stroke, and 11 age-matched healthy controls, and adjusted individual task difficulty (by varying stimulus presentation times in participants) in order to reach approximately equal error rates between neglect patients and controls. Results showed that, while both omission and substitution errors were frequently produced in neglect patients and controls, only omissions appeared neglect-specific when task difficulty was adapted between groups. Analyses of individual letter positions within words revealed that the spatial distribution of reading errors in the neglect dyslexic patients followed an almost linear increase from the end to the beginning of the word (right-to-left-gradient). Both, the gradient in error positions and the predominance of omission errors presented a neglect-specific pattern. Consistent with current models of visual word processing, these findings suggest that ND reflects sublexical, visuospatial attentional mechanisms in letter string encoding.

  19. A neural fuzzy controller learning by fuzzy error propagation

    NASA Technical Reports Server (NTRS)

    Nauck, Detlef; Kruse, Rudolf

    1992-01-01

    In this paper, we describe a procedure to integrate techniques for the adaptation of membership functions in a linguistic variable based fuzzy control environment by using neural network learning principles. This is an extension to our work. We solve this problem by defining a fuzzy error that is propagated back through the architecture of our fuzzy controller. According to this fuzzy error and the strength of its antecedent each fuzzy rule determines its amount of error. Depending on the current state of the controlled system and the control action derived from the conclusion, each rule tunes the membership functions of its antecedent and its conclusion. By this we get an unsupervised learning technique that enables a fuzzy controller to adapt to a control task by knowing just about the global state and the fuzzy error.

  20. A neural fuzzy controller learning by fuzzy error propagation

    NASA Technical Reports Server (NTRS)

    Nauck, Detlef; Kruse, Rudolf

    1992-01-01

    In this paper, we describe a procedure to integrate techniques for the adaptation of membership functions in a linguistic variable based fuzzy control environment by using neural network learning principles. This is an extension to our work. We solve this problem by defining a fuzzy error that is propagated back through the architecture of our fuzzy controller. According to this fuzzy error and the strength of its antecedent each fuzzy rule determines its amount of error. Depending on the current state of the controlled system and the control action derived from the conclusion, each rule tunes the membership functions of its antecedent and its conclusion. By this we get an unsupervised learning technique that enables a fuzzy controller to adapt to a control task by knowing just about the global state and the fuzzy error.

  1. Inrush Current Control Circuit

    NASA Technical Reports Server (NTRS)

    Cole, Steven W. (Inventor)

    2002-01-01

    An inrush current control circuit having an input terminal connected to a DC power supply and an output terminal connected to a load capacitor limits the inrush current that charges up the load capacitor during power up of a system. When the DC power supply applies a DC voltage to the input terminal, the inrush current control circuit produces a voltage ramp at the load capacitor instead of an abrupt DC voltage. The voltage ramp results in a constant low level current to charge up the load capacitor, greatly reducing the current drain on the DC power supply.

  2. A concatenated coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Lin, S.

    1985-01-01

    A concatenated coding scheme for error control in data communications is analyzed. The inner code is used for both error correction and detection, however the outer code is used only for error detection. A retransmission is requested if the outer code detects the presence of errors after the inner code decoding. The probability of undetected error of the above error control scheme is derived and upper bounded. Two specific exmaples are analyzed. In the first example, the inner code is a distance-4 shortened Hamming code with generator polynomial (X+1)(X(6)+X+1) = X(7)+X(6)+X(2)+1 and the outer code is a distance-4 shortened Hamming code with generator polynomial (X+1)X(15+X(14)+X(13)+X(12)+X(4)+X(3)+X(2)+X+1) = X(16)+X(12)+X(5)+1 which is the X.25 standard for packet-switched data network. This example is proposed for error control on NASA telecommand links. In the second example, the inner code is the same as that in the first example but the outer code is a shortened Reed-Solomon code with symbols from GF(2(8)) and generator polynomial (X+1)(X+alpha) where alpha is a primitive element in GF(z(8)).

  3. Error-control techniques for data communication

    NASA Astrophysics Data System (ADS)

    Weldon, E. J., Jr.

    A review of available techniques for increasing reliability in data communication links is presented. The methods all include error correction and retransmission (ARQ), and attention is focused on redundancy of transmission being activated only after errors have been detected. ARQ is currently performed in stop-and-wait or continuous modes. The continuous mode consists of blocks of data transmission followed by responses, both numerically defined so that data blocks can be transmitted in bursts while a response to an initial transmission is being sent. Negatively acknowledged (NACKed) blocks with errors are transmitted a second time, while error-free acknowledgements (ACKs) are transmitted only once. Data blocks are stored in a buffer memory, which will reject even correct blocks if filled. A data link, transmitter, receiver, and algorithm are described for optimized data transmission.

  4. Error Correction, Control Systems and Fuzzy Logic

    NASA Technical Reports Server (NTRS)

    Smith, Earl B.

    2004-01-01

    This paper will be a discussion on dealing with errors. While error correction and communication is important when dealing with spacecraft vehicles, the issue of control system design is also important. There will be certain commands that one wants a motion device to execute. An adequate control system will be necessary to make sure that the instruments and devices will receive the necessary commands. As it will be discussed later, the actual value will not always be equal to the intended or desired value. Hence, an adequate controller will be necessary so that the gap between the two values will be closed.

  5. Measurement process error determination and control

    SciTech Connect

    Everhart, J.

    1992-01-01

    Traditional production processes have required repeated inspection activities to assure product quality. A typical production process follows this pattern: production makes product; production inspects product; Quality Control (QC) inspects product to ensure production inspected properly QC then inspects the product on a different gage to ensure the production gage performance; and QC often inspects on a different day to determine environmental effect. All of these costly inspection activities are due to the lack of confidence in the initial production measurement. The Process Measurement Assurance Program (PMAP) is a method of determining and controlling measurement error in design, development, and production. It is a preventive rather than an appraisal method that determines, improves, and controls the error in the measurement process, including measurement equipment, environment, procedure, and personnel. PMAP expands the concept of the Measurement Assurance Program developed in the 1960's by the National Bureau of Standards (NBS), today known as the National Institute of Standards and Technology (NIST). PMAP acts as a bridge in the gap between the Metrology Laboratory and the production environment by introducing standards (or certified parts) into the production process. These certified control standards are then measured as part of the production process. A control system is present to examine the measurement results of the control standards before, during, and after the manufacturing and measuring of the product. The results of the PMAP control charts determine random uncertainty and systematic (bias from the standard) error of the measurement process. The combinations of these uncertainties determine the margin of error of the measurement process. The total measurement process error is determined by combining the margin of error and the uncertainty in the control standard.

  6. Measurement process error determination and control

    SciTech Connect

    Everhart, J.

    1992-11-01

    Traditional production processes have required repeated inspection activities to assure product quality. A typical production process follows this pattern: production makes product; production inspects product; Quality Control (QC) inspects product to ensure production inspected properly QC then inspects the product on a different gage to ensure the production gage performance; and QC often inspects on a different day to determine environmental effect. All of these costly inspection activities are due to the lack of confidence in the initial production measurement. The Process Measurement Assurance Program (PMAP) is a method of determining and controlling measurement error in design, development, and production. It is a preventive rather than an appraisal method that determines, improves, and controls the error in the measurement process, including measurement equipment, environment, procedure, and personnel. PMAP expands the concept of the Measurement Assurance Program developed in the 1960`s by the National Bureau of Standards (NBS), today known as the National Institute of Standards and Technology (NIST). PMAP acts as a bridge in the gap between the Metrology Laboratory and the production environment by introducing standards (or certified parts) into the production process. These certified control standards are then measured as part of the production process. A control system is present to examine the measurement results of the control standards before, during, and after the manufacturing and measuring of the product. The results of the PMAP control charts determine random uncertainty and systematic (bias from the standard) error of the measurement process. The combinations of these uncertainties determine the margin of error of the measurement process. The total measurement process error is determined by combining the margin of error and the uncertainty in the control standard.

  7. Voltage controlled current source

    DOEpatents

    Casne, Gregory M.

    1992-01-01

    A seven decade, voltage controlled current source is described for use in testing intermediate range nuclear instruments that covers the entire test current range of from 10 picoamperes to 100 microamperes. High accuracy is obtained throughout the entire seven decades of output current with circuitry that includes a coordinated switching scheme responsive to the input signal from a hybrid computer to control the input voltage to an antilog amplifier, and to selectively connect a resistance to the antilog amplifier output to provide a continuous output current source as a function of a preset range of input voltage. An operator controlled switch provides current adjustment for operation in either a real-time simulation test mode or a time response test mode.

  8. Error control in the GCF: An information-theoretic model for error analysis and coding

    NASA Technical Reports Server (NTRS)

    Adeyemi, O.

    1974-01-01

    The structure of data-transmission errors within the Ground Communications Facility is analyzed in order to provide error control (both forward error correction and feedback retransmission) for improved communication. Emphasis is placed on constructing a theoretical model of errors and obtaining from it all the relevant statistics for error control. No specific coding strategy is analyzed, but references to the significance of certain error pattern distributions, as predicted by the model, to error correction are made.

  9. Multijoint error compensation mediates unstable object control.

    PubMed

    Cluff, Tyler; Manos, Aspasia; Lee, Timothy D; Balasubramaniam, Ramesh

    2012-08-01

    A key feature of skilled object control is the ability to correct performance errors. This process is not straightforward for unstable objects (e.g., inverted pendulum or "stick" balancing) because the mechanics of the object are sensitive to small control errors, which can lead to rapid performance changes. In this study, we have characterized joint recruitment and coordination processes in an unstable object control task. Our objective was to determine whether skill acquisition involves changes in the recruitment of individual joints or distributed error compensation. To address this problem, we monitored stick-balancing performance across four experimental sessions. We confirmed that subjects learned the task by showing an increase in the stability and length of balancing trials across training sessions. We demonstrated that motor learning led to the development of a multijoint error compensation strategy such that after training, subjects preferentially constrained joint angle variance that jeopardized task performance. The selective constraint of destabilizing joint angle variance was an important metric of motor learning. Finally, we performed a combined uncontrolled manifold-permutation analysis to ensure the variance structure was not confounded by differences in the variance of individual joint angles. We showed that reliance on multijoint error compensation increased, whereas individual joint variation (primarily at the wrist joint) decreased systematically with training. We propose a learning mechanism that is based on the accurate estimation of sensory states.

  10. Human error in hospitals and industrial accidents: current concepts.

    PubMed

    Spencer, F C

    2000-10-01

    Most data concerning errors and accidents are from industrial accidents and airline injuries. General Electric, Alcoa, and Motorola, among others, all have reported complex programs that resulted in a marked reduction in frequency of worker injuries. In the field of medicine, however, with the outstanding exception of anesthesiology, there is a paucity of information, most reports referring to the 1984 Harvard-New York State Study, more than 16 years ago. This scarcity of information indicates the complexity of the problem. It seems very unlikely that simple exhortation or additional regulations will help because the problem lies principally in the multiple human-machine interfaces that constitute modern medical care. The absence of success stories also indicates that the best methods have to be learned by experience. A liaison with industry should be helpful, although the varieties of human illness are far different from a standardized manufacturing process. Concurrent with the studies of industrial and nuclear accidents, cognitive psychologists have intensively studied how the brain stores and retrieves information. Several concepts have emerged. First, errors are not character defects to be treated by the classic approach of discipline and education, but are byproducts of normal thinking that occur frequently. Second, major accidents are rarely causedby a single error; instead, they are often a combination of chronic system errors, termed latent errors. Identifying and correcting these latent errors should be the principal focus for corrective planning rather than searching for an individual culprit. This nonpunitive concept of errors is a key basis for an effective reporting system, brilliantly demonstrated in aviation with the ASRS system developed more than 25 years ago. The ASRS currently receives more than 30,000 reports annually and is credited with the remarkable increase in safety of airplane travel. Adverse drug events constitute about 25% of hospital

  11. High Current Power Controller

    DTIC Science & Technology

    1981-04-01

    AFWAL-TR-81- 2016 U iui.N HIGH CURRENT Ŕ POWER CONTROLLER P. E. McCOLLUM Audwo ROCKWELL INTERNATIONAL AUTONETICS STRATEGIC SYSTEMS DIVISION 3370...personnel. During norm3l operation, HCP \\.s pose no hazard, bLt unde- certain operating conditions potential noaza-ds do exist. They are: (1) During

  12. Error-control techniques for digital communication

    NASA Astrophysics Data System (ADS)

    Michelson, A. M.; Levesque, A. H.

    The reliable transmission of digital information is discussed, taking into account the communication system design problem, the elements of a digital communication system, important channel models, information theory and channel capacity, modulation performance on the AWGN channel, and combined modulation and coding for efficient signal design. Other topics studied are related to fundamental and simple block codes, the algebra of linear block codes, binary cyclic codes and BCH codes, decoding techniques for binary BCH codes, nonbinary BCH codes and Reed-Solomon codes, the performance of linear block codes with bounded-distance decoding an introduction to convolutional codes, maximum likelihood decoding of convolutional codes, sequential decoding, and applications of error-control coding. Attention is given to groups, fields, vector spaces, binary linear block codes, the parity-check matrix revisited, dual codes, Hamming distance and the weight distribution, code geometry and error-correction capability, and the representations of finite fields.

  13. Performance analysis of ARQ error controls under Markovian block error pattern

    NASA Astrophysics Data System (ADS)

    Cho, Young Jong; Un, Chong Kwan

    1994-02-01

    In this paper, we investigate the effect of forward/backward channel memory (statistical dependence in the occurrence of transmission errors) on ARQ error controls. To take into account the effect of backward channel errors in the performance analysis, we suppose some modified ARQ schemes that have an effective retransmission strategy to prevent the deadlock incurred by the errors on acknowledgments. In the study, we consider two modified go-back-N schemes with timer control and with buffer control.

  14. ARQ error control using sequential decoding

    NASA Astrophysics Data System (ADS)

    Drukarev, A.; Costello, D. J., Jr.

    An ARQ error control algorithm is proposed that eliminates failures by using repeat requests; the algorithm is a modification of the stack sequential decoding algorithm. The decoder monitors the slope of the metric of every path in the stack, and when the slope for the path at the top of the stack falls below a predetermined threshold a retransmission request is generated; a time-out retransmission strategy is used as well. It is shown that when a retransmission request occurs it is not necessary to retransmit the entire packet. Factors which influence the performance of the algorithm are discussed along with several possible applications.

  15. Type I Error Control for Tree Classification

    PubMed Central

    Jung, Sin-Ho; Chen, Yong; Ahn, Hongshik

    2014-01-01

    Binary tree classification has been useful for classifying the whole population based on the levels of outcome variable that is associated with chosen predictors. Often we start a classification with a large number of candidate predictors, and each predictor takes a number of different cutoff values. Because of these types of multiplicity, binary tree classification method is subject to severe type I error probability. Nonetheless, there have not been many publications to address this issue. In this paper, we propose a binary tree classification method to control the probability to accept a predictor below certain level, say 5%. PMID:25452689

  16. Modeling-Error-Driven Performance-Seeking Direct Adaptive Control

    NASA Technical Reports Server (NTRS)

    Kulkarni, Nilesh V.; Kaneshige, John; Krishnakumar, Kalmanje; Burken, John

    2008-01-01

    This paper presents a stable discrete-time adaptive law that targets modeling errors in a direct adaptive control framework. The update law was developed in our previous work for the adaptive disturbance rejection application. The approach is based on the philosophy that without modeling errors, the original control design has been tuned to achieve the desired performance. The adaptive control should, therefore, work towards getting this performance even in the face of modeling uncertainties/errors. In this work, the baseline controller uses dynamic inversion with proportional-integral augmentation. Dynamic inversion is carried out using the assumed system model. On-line adaptation of this control law is achieved by providing a parameterized augmentation signal to the dynamic inversion block. The parameters of this augmentation signal are updated to achieve the nominal desired error dynamics. Contrary to the typical Lyapunov-based adaptive approaches that guarantee only stability, the current approach investigates conditions for stability as well as performance. A high-fidelity F-15 model is used to illustrate the overall approach.

  17. CMOS current controlled fully balanced current conveyor

    NASA Astrophysics Data System (ADS)

    Chunhua, Wang; Qiujing, Zhang; Haiguang, Liu

    2009-07-01

    This paper presents a current controlled fully balanced second-generation current conveyor circuit (CF-BCCII). The proposed circuit has the traits of fully balanced architecture, and its X-Y terminals are current controllable. Based on the CFBCCII, two biquadratic universal filters are also proposed as its applications. The CFBCCII circuits and the two filters were fabricated with chartered 0.35-μm CMOS technology; with ±1.65 V power supply voltage, the total power consumption of the CFBCCII circuit is 3.6 mW. Comparisons between measured and HSpice simulation results are also given.

  18. Controlled current inductors

    NASA Technical Reports Server (NTRS)

    Thaler, S.

    1970-01-01

    Magnetic permeability and shape of special core inserts are varied to produce desired changes in saturation characteristics of current dependent inductor, thus improving its inductance-to-current properties. Materials and saturation levels of the core pieces are selected to permit a wide variety of relationships between inductance and current.

  19. Permanence analysis of a concatenated coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Costello, D. J., Jr.; Lin, S.; Kasami, T.

    1983-01-01

    A concatenated coding scheme for error control in data communications is analyzed. In this scheme, the inner code is used for both error correction and detection, however, the outer code is used only for error detection. A retransmission is requested if the outer code detects the presence of errors after the inner code decoding. Probability of undetected error is derived and bounded. A particular example, proposed for the planetary program, is analyzed.

  20. Current control circuitry

    DOEpatents

    Taubman, Matthew S [Richland, WA

    2005-03-15

    Among the embodiments of the present invention is an apparatus that includes a transistor (30), a servo device (40), and a current source (50). The servo device (40) is operable to provide a common base mode of operation of the transistor (30) by maintaining an approximately constant voltage level at the transistor base (32b). The current source (150) is operable to provide a bias current to the transistor (30). A first device (24) provides an input signal to an electrical node (70) positioned between the emitter (32e) of the transistor (30) and the current source (50). A second device (26) receives an output signal from the collector (32c) of the transistor (30).

  1. Computerised physician order entry-related medication errors: analysis of reported errors and vulnerability testing of current systems

    PubMed Central

    Schiff, G D; Amato, M G; Eguale, T; Boehne, J J; Wright, A; Koppel, R; Rashidee, A H; Elson, R B; Whitney, D L; Thach, T-T; Bates, D W; Seger, A C

    2015-01-01

    Importance Medication computerised provider order entry (CPOE) has been shown to decrease errors and is being widely adopted. However, CPOE also has potential for introducing or contributing to errors. Objectives The objectives of this study are to (a) analyse medication error reports where CPOE was reported as a ‘contributing cause’ and (b) develop ‘use cases’ based on these reports to test vulnerability of current CPOE systems to these errors. Methods A review of medication errors reported to United States Pharmacopeia MEDMARX reporting system was made, and a taxonomy was developed for CPOE-related errors. For each error we evaluated what went wrong and why and identified potential prevention strategies and recurring error scenarios. These scenarios were then used to test vulnerability of leading CPOE systems, asking typical users to enter these erroneous orders to assess the degree to which these problematic orders could be entered. Results Between 2003 and 2010, 1.04 million medication errors were reported to MEDMARX, of which 63 040 were reported as CPOE related. A review of 10 060 CPOE-related cases was used to derive 101 codes describing what went wrong, 67 codes describing reasons why errors occurred, 73 codes describing potential prevention strategies and 21 codes describing recurring error scenarios. Ability to enter these erroneous order scenarios was tested on 13 CPOE systems at 16 sites. Overall, 298 (79.5%) of the erroneous orders were able to be entered including 100 (28.0%) being ‘easily’ placed, another 101 (28.3%) with only minor workarounds and no warnings. Conclusions and relevance Medication error reports provide valuable information for understanding CPOE-related errors. Reports were useful for developing taxonomy and identifying recurring errors to which current CPOE systems are vulnerable. Enhanced monitoring, reporting and testing of CPOE systems are important to improve CPOE safety. PMID:25595599

  2. An error control system with multiple-stage forward error corrections

    NASA Technical Reports Server (NTRS)

    Takata, Toyoo; Fujiwara, Toru; Kasami, Tadao; Lin, Shu

    1990-01-01

    A robust error-control coding system is presented. This system is a cascaded FEC (forward error control) scheme supported by parity retransmissions for further error correction in the erroneous data words. The error performance and throughput efficiency of the system are analyzed. Two specific examples of the error-control system are studied. The first example does not use an inner code, and the outer code, which is not interleaved, is a shortened code of the NASA standard RS code over GF(28). The second example, as proposed for NASA, uses the same shortened RS code as the base outer code C2, except that it is interleaved to a depth of 2. It is shown that both examples provide high reliability and throughput efficiency even for high channel bit-error rates in the range of 0.01.

  3. An error control system with multiple-stage forward error corrections

    NASA Technical Reports Server (NTRS)

    Takata, Toyoo; Fujiwara, Toru; Kasami, Tadao; Lin, Shu

    1990-01-01

    A robust error-control coding system is presented. This system is a cascaded FEC (forward error control) scheme supported by parity retransmissions for further error correction in the erroneous data words. The error performance and throughput efficiency of the system are analyzed. Two specific examples of the error-control system are studied. The first example does not use an inner code, and the outer code, which is not interleaved, is a shortened code of the NASA standard RS code over GF(28). The second example, as proposed for NASA, uses the same shortened RS code as the base outer code C2, except that it is interleaved to a depth of 2. It is shown that both examples provide high reliability and throughput efficiency even for high channel bit-error rates in the range of 0.01.

  4. Application of Interval Analysis to Error Control.

    DTIC Science & Technology

    1976-09-01

    We give simple examples of ways in which interval arithmetic can be used to alert instabilities in computer algorithms , roundoff error accumulation, and even the effects of hardware inadequacies. This paper is primarily tutorial. (Author)

  5. A Java Applet for Illustrating Internet Error Control

    ERIC Educational Resources Information Center

    Holliday, Mark A.

    2004-01-01

    This paper discusses the author's experiences developing a Java applet that illustrates how error control is implemented in the Transmission Control Protocol (TCP). One section discusses the concepts which the TCP error control Java applet is intended to convey, while the nature of the Java applet is covered in another section. The author…

  6. A Java Applet for Illustrating Internet Error Control

    ERIC Educational Resources Information Center

    Holliday, Mark A.

    2004-01-01

    This paper discusses the author's experiences developing a Java applet that illustrates how error control is implemented in the Transmission Control Protocol (TCP). One section discusses the concepts which the TCP error control Java applet is intended to convey, while the nature of the Java applet is covered in another section. The author…

  7. Attitude control with realization of linear error dynamics

    NASA Technical Reports Server (NTRS)

    Paielli, Russell A.; Bach, Ralph E.

    1993-01-01

    An attitude control law is derived to realize linear unforced error dynamics with the attitude error defined in terms of rotation group algebra (rather than vector algebra). Euler parameters are used in the rotational dynamics model because they are globally nonsingular, but only the minimal three Euler parameters are used in the error dynamics model because they have no nonlinear mathematical constraints to prevent the realization of linear error dynamics. The control law is singular only when the attitude error angle is exactly pi rad about any eigenaxis, and a simple intuitive modification at the singularity allows the control law to be used globally. The forced error dynamics are nonlinear but stable. Numerical simulation tests show that the control law performs robustly for both initial attitude acquisition and attitude control.

  8. Attitude control with realization of linear error dynamics

    NASA Technical Reports Server (NTRS)

    Paielli, Russell A.; Bach, Ralph E.

    1993-01-01

    An attitude control law is derived to realize linear unforced error dynamics with the attitude error defined in terms of rotation group algebra (rather than vector algebra). Euler parameters are used in the rotational dynamics model because they are globally nonsingular, but only the minimal three Euler parameters are used in the error dynamics model because they have no nonlinear mathematical constraints to prevent the realization of linear error dynamics. The control law is singular only when the attitude error angle is exactly pi rad about any eigenaxis, and a simple intuitive modification at the singularity allows the control law to be used globally. The forced error dynamics are nonlinear but stable. Numerical simulation tests show that the control law performs robustly for both initial attitude acquisition and attitude control.

  9. Reducing Pointing Errors During Cassini Reaction Control System Orbit Trim Maneuvers

    NASA Technical Reports Server (NTRS)

    Rizvi, Farheen

    2013-01-01

    The effect of altering a gain parameter in the Cassini reaction control system (RCS) delta-V controller on the maneuver execution errors during orbit trim maneuvers (OTMs) is explored. Cassini consists of two reaction control thruster branches (A & B) each with eight thrusters. Currently, the B-branch is operational while the A-branch serves as a back-up. The four Z-thrusters control the X and Y-axes, while the four Y-thrusters control the Z-axis. During an OTM, the Z-thrusters fire to maintain the X and Y-axes pointing within an attitude control dead-zone (-10 to 10 milliradians). The errors do not remain at zero due to pointing error sources such as spacecraft center of mass offset from the geometric center of the Z-facing thrusters, and variability in the thruster forces due to the thruster hardware differences. The delta-V reaction control system (RCS) controller ensures that the attitude error remains within this dead-zone. Gain parameters within the RCS delta-V controller affect the maneuver execution errors. Different parameter values are used to explore effect on these errors. It is found that pointing error decreases and magnitude error increases rapidly for gain parameters 10 times greater than the current parameter values used in the flight software.

  10. Reducing Pointing Errors During Cassini Reaction Control System Orbit Trim Maneuvers

    NASA Technical Reports Server (NTRS)

    Rizvi, Farheen

    2013-01-01

    The effect of altering a gain parameter in the Cassini reaction control system (RCS) delta-V controller on the maneuver execution errors during orbit trim maneuvers (OTMs) is explored. Cassini consists of two reaction control thruster branches (A & B) each with eight thrusters. Currently, the B-branch is operational while the A-branch serves as a back-up. The four Z-thrusters control the X and Y-axes, while the four Y-thrusters control the Z-axis. During an OTM, the Z-thrusters fire to maintain the X and Y-axes pointing within an attitude control dead-zone (-10 to 10 milliradians). The errors do not remain at zero due to pointing error sources such as spacecraft center of mass offset from the geometric center of the Z-facing thrusters, and variability in the thruster forces due to the thruster hardware differences. The delta-V reaction control system (RCS) controller ensures that the attitude error remains within this dead-zone. Gain parameters within the RCS delta-V controller affect the maneuver execution errors. Different parameter values are used to explore effect on these errors. It is found that pointing error decreases and magnitude error increases rapidly for gain parameters 10 times greater than the current parameter values used in the flight software.

  11. Designing to Control Flight Crew Errors

    NASA Technical Reports Server (NTRS)

    Schutte, Paul C.; Willshire, Kelli F.

    1997-01-01

    It is widely accepted that human error is a major contributing factor in aircraft accidents. There has been a significant amount of research in why these errors occurred, and many reports state that the design of flight deck can actually dispose humans to err. This research has led to the call for changes in design according to human factors and human-centered principles. The National Aeronautics and Space Administration's (NASA) Langley Research Center has initiated an effort to design a human-centered flight deck from a clean slate (i.e., without constraints of existing designs.) The effort will be based on recent research in human-centered design philosophy and mission management categories. This design will match the human's model of the mission and function of the aircraft to reduce unnatural or non-intuitive interfaces. The product of this effort will be a flight deck design description, including training and procedures, and a cross reference or paper trail back to design hypotheses, and an evaluation of the design. The present paper will discuss the philosophy, process, and status of this design effort.

  12. Servo control booster system for minimizing following error

    DOEpatents

    Wise, William L.

    1985-01-01

    A closed-loop feedback-controlled servo system is disclosed which reduces command-to-response error to the system's position feedback resolution least increment, .DELTA.S.sub.R, on a continuous real-time basis for all operating speeds. The servo system employs a second position feedback control loop on a by exception basis, when the command-to-response error .gtoreq..DELTA.S.sub.R, to produce precise position correction signals. When the command-to-response error is less than .DELTA.S.sub.R, control automatically reverts to conventional control means as the second position feedback control loop is disconnected, becoming transparent to conventional servo control means. By operating the second unique position feedback control loop used herein at the appropriate clocking rate, command-to-response error may be reduced to the position feedback resolution least increment. The present system may be utilized in combination with a tachometer loop for increased stability.

  13. Steady-state error of a system with fuzzy controller.

    PubMed

    Butkiewicz, B S

    1998-01-01

    We consider the problem of control error of a fuzzy system with feedback. The system consists of a plant, linear or nonlinear, fuzzy controller, and feedback loop. As controller we use both PD and PI fuzzy type controllers. We apply different t-norm and co-norm: logic, algebraic, Yager, Hamacher, bounded, drastic, etc. in the process of fuzzy reasoning. Triangular shape of membership functions is supposed, but we generalize the results obtained. Steady-state error of a system is calculated. We have obtained very interesting results. The steady-state error is identical for pairs of triangular t- and co-norms.

  14. Error control for reliable digital data transmission and storage systems

    NASA Technical Reports Server (NTRS)

    Costello, D. J., Jr.; Deng, R. H.

    1985-01-01

    A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256K-bit DRAM's are organized in 32Kx8 bit-bytes. Byte oriented codes such as Reed Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. In this paper we present some special decoding techniques for extended single-and-double-error-correcting RS codes which are capable of high speed operation. These techniques are designed to find the error locations and the error values directly from the syndrome without having to use the iterative alorithm to find the error locator polynomial. Two codes are considered: (1) a d sub min = 4 single-byte-error-correcting (SBEC), double-byte-error-detecting (DBED) RS code; and (2) a d sub min = 6 double-byte-error-correcting (DBEC), triple-byte-error-detecting (TBED) RS code.

  15. Multiple Cognitive Control Effects of Error Likelihood and Conflict

    PubMed Central

    Brown, Joshua W.

    2010-01-01

    Recent work on cognitive control has suggested a variety of performance monitoring functions of the anterior cingulate cortex, such as errors, conflict, error likelihood, and others. Given the variety of monitoring effects, a corresponding variety of control effects on behavior might be expected. This paper explores whether conflict and error likelihood produce distinct cognitive control effects on behavior, as measured by response time. A change signal task (Brown & Braver, 2005) was modified to include conditions of likely errors due to tardy as well as premature responses, in conditions with and without conflict. The results discriminate between competing hypotheses of independent vs. interacting conflict and error likelihood control effects. Specifically, the results suggest that the likelihood of premature vs. tardy response errors can lead to multiple distinct control effects, which are independent of cognitive control effects driven by response conflict. As a whole, the results point to the existence of multiple distinct cognitive control mechanisms and challenge existing models of cognitive control that incorporate only a single control signal. PMID:19030873

  16. Data management for error compensation and process control

    NASA Astrophysics Data System (ADS)

    Bandy, Herbert T.; Gilsinn, David E.

    1995-11-01

    Strategies for managing data flow are described for a system which controls processes to compensate machine tool and process errors. A CAD representation of the part is the basis for generating the data used in the processes and analyses. A process-oriented view of part features is used for tracking data regarding design, part programming, manufacture, error compensation, and inspection. Part ID and file name nomenclature have been developed to facilitate data identification. All data are stored in a database, enabling error trends over time to be studied so that error compensation algorithms may be refined.

  17. Composite Gauss-Legendre Quadrature with Error Control

    ERIC Educational Resources Information Center

    Prentice, J. S. C.

    2011-01-01

    We describe composite Gauss-Legendre quadrature for determining definite integrals, including a means of controlling the approximation error. We compare the form and performance of the algorithm with standard Newton-Cotes quadrature. (Contains 1 table.)

  18. Composite Gauss-Legendre Quadrature with Error Control

    ERIC Educational Resources Information Center

    Prentice, J. S. C.

    2011-01-01

    We describe composite Gauss-Legendre quadrature for determining definite integrals, including a means of controlling the approximation error. We compare the form and performance of the algorithm with standard Newton-Cotes quadrature. (Contains 1 table.)

  19. Residual-based Methods for Controlling Discretization Error in CFD

    DTIC Science & Technology

    2015-08-24

    Adjoint- based h–p Adaptive Discontinuous Galerkin Methods for the 2D Compressible Euler Equations,” Journal of Computational Physics, Vol. 228, No. 20...AFRL-AFOSR-VA-TR-2015-0256 Residual- based Methods for Controlling Discretization Error in CFD Chris Roy VIRGINIA POLYTECHNIC INST AND STATE...30-04-2015 4. TITLE AND SUBTITLE Residual- based Methods for Controlling Discretization Error in CFD 5a. CONTRACT NUMBER FA9550-12-1-0173 5b. GRANT

  20. Model reference adaptive control with an augmented error signal

    NASA Technical Reports Server (NTRS)

    Monopoli, R. V.

    1974-01-01

    It is shown how globally stable model reference adaptive control systems may be designed when one has access to only the plant's input and output signals. Controllers for single input-single output, nonlinear, nonautonomous plants are developed based on Lyapunov's direct method and the Meyer-Kalman-Yacubovich lemma. Derivatives of the plant output are not required, but are replaced by filtered derivative signals. An augmented error signal replaces the error normally used, which is defined as the difference between the model and plant outputs. However, global stability is assured in the sense that the normally used error signal approaches zero asymptotically.

  1. Error control of iterative linear solvers for integrated groundwater models.

    PubMed

    Dixon, Matthew F; Bai, Zhaojun; Brush, Charles F; Chung, Francis I; Dogrul, Emin C; Kadir, Tariq N

    2011-01-01

    An open problem that arises when using modern iterative linear solvers, such as the preconditioned conjugate gradient method or Generalized Minimum RESidual (GMRES) method, is how to choose the residual tolerance in the linear solver to be consistent with the tolerance on the solution error. This problem is especially acute for integrated groundwater models, which are implicitly coupled to another model, such as surface water models, and resolve both multiple scales of flow and temporal interaction terms, giving rise to linear systems with variable scaling. This article uses the theory of "forward error bound estimation" to explain the correspondence between the residual error in the preconditioned linear system and the solution error. Using examples of linear systems from models developed by the US Geological Survey and the California State Department of Water Resources, we observe that this error bound guides the choice of a practical measure for controlling the error in linear systems. We implemented a preconditioned GMRES algorithm and benchmarked it against the Successive Over-Relaxation (SOR) method, the most widely known iterative solver for nonsymmetric coefficient matrices. With forward error control, GMRES can easily replace the SOR method in legacy groundwater modeling packages, resulting in the overall simulation speedups as large as 7.74×. This research is expected to broadly impact groundwater modelers through the demonstration of a practical and general approach for setting the residual tolerance in line with the solution error tolerance and presentation of GMRES performance benchmarking results.

  2. Requirements and considerations of the surface error control for the active reflector of FAST

    NASA Astrophysics Data System (ADS)

    Wu, MingChang; Wang, QiMing; Gu, XueDong; Zhao, BaoQing

    2012-09-01

    The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is currently under construction at a Karst depression in the Guizhou province of China. The active reflector of the telescope is composed of 4395 triangular panels laid on a cable-net structure. The aperture of the spherical surface is 500 meters, with open angle of about 110~120 degrees. Acting as the nodes of the reflector, the joint of these panels are adjusted by 2235 down-tie cables drawn by actuators. The RMS error of the parabola reflector is expected to be 5mm. To form the parabola shape of the reflector, for each of the actuators, a minimal working stroke of 950mm is required, with maximal speed of 1.6mm/s at the load of 50kN. Considering the elastic deformation of the down-tie cable and other factors, a positioning error within 0.25mm is required for the actuators. In this paper, the base formula for the motion of a general actuator at a typical observation time is studied analytically. The results are used to estimate the control error of the actuators and the pointing error of the whole reflector. Based on the designed error budgets, a statistical method is employed to estimate the overall surface error of the parabola reflector. The overall surface error is a comprehensive result of the panel design error, panel fabrication error, thermal deformation error, panel wind load induced error, cable-net error, installation error, measurement and control error etc. The results may be used as a reference in the measurement and control of the active reflector when in operation.

  3. Acetylcholine mediates behavioral and neural post-error control.

    PubMed

    Danielmeier, Claudia; Allen, Elena A; Jocham, Gerhard; Onur, Oezguer A; Eichele, Tom; Ullsperger, Markus

    2015-06-01

    Humans often commit errors when they are distracted by irrelevant information and no longer focus on what is relevant to the task at hand. Adjustments following errors are essential for optimizing goal achievement. The posterior medial frontal cortex (pMFC), a key area for monitoring errors, has been shown to trigger such post-error adjustments by modulating activity in visual cortical areas. However, the mechanisms by which pMFC controls sensory cortices are unknown. We provide evidence for a mechanism based on pMFC-induced recruitment of cholinergic projections to task-relevant sensory areas. Using fMRI in healthy volunteers, we found that error-related pMFC activity predicted subsequent adjustments in task-relevant visual brain areas. In particular, following an error, activity increased in those visual cortical areas involved in processing task-relevant stimulus features, whereas activity decreased in areas representing irrelevant, distracting features. Following treatment with the muscarinic acetylcholine receptor antagonist biperiden, activity in visual areas was no longer under control of error-related pMFC activity. This was paralleled by abolished post-error behavioral adjustments under biperiden. Our results reveal a prominent role of acetylcholine in cognitive control that has not been recognized thus far. Regaining optimal performance after errors critically depends on top-down control of perception driven by the pMFC and mediated by acetylcholine. This may explain the lack of adaptivity in conditions with reduced availability of cortical acetylcholine, such as Alzheimer's disease.

  4. Magnetoelectric control of spin currents

    SciTech Connect

    Gómez, J. E.; Vargas, J. M.; Avilés-Félix, L.; Butera, A.

    2016-06-13

    The ability to control the spin current injection has been explored on a hybrid magnetoelectric system consisting of a (011)-cut ferroelectric lead magnesium niobate-lead titanate (PMNT) single crystal, a ferromagnetic FePt alloy, and a metallic Pt. With this PMNT/FePt/Pt structure we have been able to control the magnetic field position or the microwave excitation frequency at which the spin pumping phenomenon between FePt and Pt occurs. We demonstrate that the magnetoelectric heterostructure operating in the L-T (longitudinal magnetized-transverse polarized) mode couples the PMNT crystal to the magnetostrictive FePt/Pt bilayer, displaying a strong magnetoelectric coefficient of ∼140 Oe cm kV{sup −1}. Our results show that this mechanism can be effectively exploited as a tunable spin current intensity emitter and open the possibility to create an oscillating or a bistable switch to effectively manipulate spin currents.

  5. Floating-point system quantization errors in digital control systems

    NASA Technical Reports Server (NTRS)

    Phillips, C. L.

    1973-01-01

    The results are reported of research into the effects on system operation of signal quantization in a digital control system. The investigation considered digital controllers (filters) operating in floating-point arithmetic in either open-loop or closed-loop systems. An error analysis technique is developed, and is implemented by a digital computer program that is based on a digital simulation of the system. As an output the program gives the programing form required for minimum system quantization errors (either maximum of rms errors), and the maximum and rms errors that appear in the system output for a given bit configuration. The program can be integrated into existing digital simulations of a system.

  6. Developing control charts to review and monitor medication errors.

    PubMed

    Ciminera, J L; Lease, M P

    1992-03-01

    There is a need to monitor reported medication errors in a hospital setting. Because the quantity of errors vary due to external reporting, quantifying the data is extremely difficult. Typically, these errors are reviewed using classification systems that often have wide variations in the numbers per class per month. The authors recommend the use of control charts to review historical data and to monitor future data. The procedure they have adopted is a modification of schemes using absolute (i.e., positive) values of successive differences to estimate the standard deviation when only single incidence values are available in time rather than sample averages, and when many successive differences may be zero.

  7. On the undetected error probability of a concatenated coding scheme for error control

    NASA Technical Reports Server (NTRS)

    Deng, H.; Costello, D. J., Jr.

    1984-01-01

    Consider a concatenated coding scheme for error control on a binary symmetric channel, called the inner channel. The bit error rate (BER) of the channel is correspondingly called the inner BER, and is denoted by Epsilon (sub i). Two linear block codes, C(sub f) and C(sub b), are used. The inner code C(sub f), called the frame code, is an (n,k) systematic binary block code with minimum distance, d(sub f). The frame code is designed to correct + or fewer errors and simultaneously detect gamma (gamma +) or fewer errors, where + + gamma + 1 = to or d(sub f). The outer code C(sub b) is either an (n(sub b), K(sub b)) binary block with a n(sub b) = mk, or an (n(sub b), k(Sub b) maximum distance separable (MDS) code with symbols from GF(q), where q = 2(b) and the code length n(sub b) satisfies n(sub)(b) = mk. The integerim is the number of frames. The outercode is designed for error detection only.

  8. Decoupling congestion control and error control mechanisms in TCP and evaluating their performance over broadband satellite networks

    NASA Astrophysics Data System (ADS)

    Wang, Lina; Gu, Xuemai

    2004-04-01

    In this paper, we propose a novel method to better evaluate the performance of TCP over broadband satellite networks. We decouple the most crucial parts of TCP that impact its performance in broadband satellite environments, namely congestion control and error control mechanisms. And then we re-design these two function blocks and make them become two individual parts. With these re-designed modules, we have investigated the interactions between various currently existing TCP congestion control and error control schemes, as well as their impact on TCP performance over a geostationary broadband satellite link with long propagation delay and high bit error rate. Simulation results have shown that some combinations of different congestion control and error control mechanisms can waste satellite link bandwidth with large numbers of retransmission packets and unnecessary retransmission packets. And the modified TCP NewReno implementation can avoid high amount of retransmissions and unnecessary retransmissions.

  9. When soft controls get slippery: User interfaces and human error

    SciTech Connect

    Stubler, W.F.; O`Hara, J.M.

    1998-12-01

    Many types of products and systems that have traditionally featured physical control devices are now being designed with soft controls--input formats appearing on computer-based display devices and operated by a variety of input devices. A review of complex human-machine systems found that soft controls are particularly prone to some types of errors and may affect overall system performance and safety. This paper discusses the application of design approaches for reducing the likelihood of these errors and for enhancing usability, user satisfaction, and system performance and safety.

  10. Liquid Medication Errors and Dosing Tools: A Randomized Controlled Experiment.

    PubMed

    Yin, H Shonna; Parker, Ruth M; Sanders, Lee M; Dreyer, Benard P; Mendelsohn, Alan L; Bailey, Stacy; Patel, Deesha A; Jimenez, Jessica J; Kim, Kwang-Youn A; Jacobson, Kara; Hedlund, Laurie; Smith, Michelle C J; Maness Harris, Leslie; McFadden, Terri; Wolf, Michael S

    2016-10-01

    Poorly designed labels and packaging are key contributors to medication errors. To identify attributes of labels and dosing tools that could be improved, we examined the extent to which dosing error rates are affected by tool characteristics (ie, type, marking complexity) and discordance between units of measurement on labels and dosing tools; along with differences by health literacy and language. Randomized controlled experiment in 3 urban pediatric clinics. English- or Spanish-speaking parents (n = 2110) of children ≤8 years old were randomly assigned to 1 of 5 study arms and given labels and dosing tools that varied in unit pairings. Each parent measured 9 doses of medication (3 amounts [2.5, 5, and 7.5 mL] and 3 tools [1 cup, 2 syringes (0.2- and 0.5-mL increments)]), in random order. Outcome assessed was dosing error (>20% deviation; large error defined as > 2 times the dose). A total of 84.4% of parents made ≥1 dosing error (21.0% ≥1 large error). More errors were seen with cups than syringes (adjusted odds ratio = 4.6; 95% confidence interval, 4.2-5.1) across health literacy and language groups (P < .001 for interactions), especially for smaller doses. No differences in error rates were seen between the 2 syringe types. Use of a teaspoon-only label (with a milliliter and teaspoon tool) was associated with more errors than when milliliter-only labels and tools were used (adjusted odds ratio = 1.2; 95% confidence interval, 1.01-1.4). Recommending oral syringes over cups, particularly for smaller doses, should be part of a comprehensive pediatric labeling and dosing strategy to reduce medication errors. Copyright © 2016 by the American Academy of Pediatrics.

  11. An Improved Model Predictive Current Controller of Switched Reluctance Machines Using Time-Multiplexed Current Sensor

    PubMed Central

    Li, Bingchu; Ling, Xiao; Huang, Yixiang; Gong, Liang; Liu, Chengliang

    2017-01-01

    This paper presents a fixed-switching-frequency model predictive current controller using multiplexed current sensor for switched reluctance machine (SRM) drives. The converter was modified to distinguish currents from simultaneously excited phases during the sampling period. The only current sensor installed in the converter was time division multiplexing for phase current sampling. During the commutation stage, the control steps of adjacent phases were shifted so that sampling time was staggered. The maximum and minimum duty ratio of pulse width modulation (PWM) was limited to keep enough sampling time for analog-to-digital (A/D) conversion. Current sensor multiplexing was realized without complex adjustment of either driver circuit nor control algorithms, while it helps to reduce the cost and errors introduced in current sampling due to inconsistency between sensors. The proposed controller is validated by both simulation and experimental results with a 1.5 kW three-phase 12/8 SRM. Satisfied current sampling is received with little difference compared with independent phase current sensors for each phase. The proposed controller tracks the reference current profile as accurately as the model predictive current controller with independent phase current sensors, while having minor tracking errors compared with a hysteresis current controller. PMID:28513554

  12. An Improved Model Predictive Current Controller of Switched Reluctance Machines Using Time-Multiplexed Current Sensor.

    PubMed

    Li, Bingchu; Ling, Xiao; Huang, Yixiang; Gong, Liang; Liu, Chengliang

    2017-05-17

    This paper presents a fixed-switching-frequency model predictive current controller using multiplexed current sensor for switched reluctance machine (SRM) drives. The converter was modified to distinguish currents from simultaneously excited phases during the sampling period. The only current sensor installed in the converter was time division multiplexing for phase current sampling. During the commutation stage, the control steps of adjacent phases were shifted so that sampling time was staggered. The maximum and minimum duty ratio of pulse width modulation (PWM) was limited to keep enough sampling time for analog-to-digital (A/D) conversion. Current sensor multiplexing was realized without complex adjustment of either driver circuit nor control algorithms, while it helps to reduce the cost and errors introduced in current sampling due to inconsistency between sensors. The proposed controller is validated by both simulation and experimental results with a 1.5 kW three-phase 12/8 SRM. Satisfied current sampling is received with little difference compared with independent phase current sensors for each phase. The proposed controller tracks the reference current profile as accurately as the model predictive current controller with independent phase current sensors, while having minor tracking errors compared with a hysteresis current controller.

  13. Servo control booster system for minimizing following error

    DOEpatents

    Wise, W.L.

    1979-07-26

    A closed-loop feedback-controlled servo system is disclosed which reduces command-to-response error to the system's position feedback resolution least increment, ..delta..S/sub R/, on a continuous real-time basis, for all operational times of consequence and for all operating speeds. The servo system employs a second position feedback control loop on a by exception basis, when the command-to-response error greater than or equal to ..delta..S/sub R/, to produce precise position correction signals. When the command-to-response error is less than ..delta..S/sub R/, control automatically reverts to conventional control means as the second position feedback control loop is disconnected, becoming transparent to conventional servo control means. By operating the second unique position feedback control loop used herein at the appropriate clocking rate, command-to-response error may be reduced to the position feedback resolution least increment. The present system may be utilized in combination with a tachometer loop for increased stability.

  14. The importance of robust error control in data compression applications

    NASA Technical Reports Server (NTRS)

    Woolley, S. I.

    1993-01-01

    Data compression has become an increasingly popular option as advances in information technology have placed further demands on data storage capabilities. With compression ratios as high as 100:1 the benefits are clear; however, the inherent intolerance of many compression formats to error events should be given careful consideration. If we consider that efficiently compressed data will ideally contain no redundancy, then the introduction of a channel error must result in a change of understanding from that of the original source. While the prefix property of codes such as Huffman enables resynchronisation, this is not sufficient to arrest propagating errors in an adaptive environment. Arithmetic, Lempel-Ziv, discrete cosine transform (DCT) and fractal methods are similarly prone to error propagating behaviors. It is, therefore, essential that compression implementations provide sufficient combatant error control in order to maintain data integrity. Ideally, this control should be derived from a full understanding of the prevailing error mechanisms and their interaction with both the system configuration and the compression schemes in use.

  15. A packet telemetry system employing ARQ error control

    NASA Technical Reports Server (NTRS)

    Greene, E. P.

    1978-01-01

    A proposed packet telemetry system employing automatic retransmission request (ARQ) mode of error control is characterized. Limitations of the present multiplexing/demultiplexing approach are considered, and the use of the proposed system in near-earth satellites in the 1980s is suggested. Onboard processing and an adaptive multiplexing technique are described, as is an elastic buffer, required because the instantaneous data rate will be different from the telemetry transmission rate. The telemetry packets would be encoded into a powerful error-detection block code. A mechanism involving temporary buffering in a long shift register will permit retransmission request from the ground station for packets received in error. The ARQ mode of operation should ensure essentially error-free transmission at lower signal-to-noise ratios and at considerably higher transmission rates than are usually used.

  16. Reliability, Safety and Error Recovery for Advanced Control Software

    NASA Technical Reports Server (NTRS)

    Malin, Jane T.

    2003-01-01

    For long-duration automated operation of regenerative life support systems in space environments, there is a need for advanced integration and control systems that are significantly more reliable and safe, and that support error recovery and minimization of operational failures. This presentation outlines some challenges of hazardous space environments and complex system interactions that can lead to system accidents. It discusses approaches to hazard analysis and error recovery for control software and challenges of supporting effective intervention by safety software and the crew.

  17. Discrete model reference adaptive control with an augmented error signal

    NASA Technical Reports Server (NTRS)

    Ionescu, T.; Monopoli, R.

    1975-01-01

    A method for designing discrete model reference adaptive control systems when one has access to only the plant's input and output signals is given. Controllers for single-input, single-output, nonlinear, nonautonomous plants are developed via Liapunov's second method. Anticipative values of the plant output are not required, but are replaced by signals easily obtained from a low-pass filter operating on the plant's output. The augmented error signal method is employed, ensuring finally that the normally used error signal also approaches zero asymptotically.

  18. Evaluation of a mixed controller that amplifies spatial errors while reducing timing errors.

    PubMed

    Marchal-Crespo, Laura; Baumann, Tanja; Fichmann, Daniela; Maassen, Steve; Duarte, Jaime E; Riener, Robert

    2016-08-01

    Previous results suggest that haptic guidance enhances learning of the timing components of motor tasks, whereas error amplification is better for learning the spatial components. In this paper we evaluate a novel mixed guidance controller that combines haptic guidance and error amplification to simultaneously promote learning of the timing and spatial components. The controller is realized using a saddle-like force field around the desired movement position. This force field has a stable manifold tangential to the trajectory that guides subjects in velocity related aspects. The force field has its unstable manifold perpendicular to the trajectory, which amplifies the normal (spatial) error. We conducted an experiment with twenty nine healthy subjects to test whether training with the mixed guidance controller resulted in better learning than training without guidance or with guidance-as-needed. Subjects trained two tasks: a continuous rhythmic task (circle) and a continuous single task (line). We found that the effectiveness of the training strategy depended on the task. Training with mixed guidance was especially beneficial for learning the timing components of the line, but limited learning of the circle. Perhaps the continuous change in the force directions during training of the circle was too difficult to interpret.

  19. When errors do not matter: weakening belief in intentional control impairs cognitive reaction to errors.

    PubMed

    Rigoni, Davide; Wilquin, Hélène; Brass, Marcel; Burle, Boris

    2013-05-01

    The belief that one can exert intentional control over behavior is deeply rooted in virtually all human beings. It has been shown that weakening such belief - e.g. by exposure to 'anti-free will' messages - can lead people to display antisocial tendencies. We propose that this cursory and irresponsible behavior may be facilitated by a breakdown of neurocognitive mechanisms underlying behavioral adjustments. In the study reported here, we tested the hypothesis that weakening belief in intentional control reduces cognitive markers of behavioral control. Participants performed a Simon task before and after reading a scientific text either denying free will (no-free will group) or not mentioning free will (control group). Results showed that the post-error slowing, a cognitive marker of performance adjustment, was reduced in the no-free will group. This reduction was proportional to a decrease of the belief in intentional control. These observations indicate that weakening the belief in free will can impact behavioral adjustment after an error, and could be the cause of antisocial and irresponsible behavior. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Floating-point system quantization errors in digital control systems

    NASA Technical Reports Server (NTRS)

    Phillips, C. L.; Vallely, D. P.

    1978-01-01

    This paper considers digital controllers (filters) operating in floating-point arithmetic in either open-loop or closed-loop systems. A quantization error analysis technique is developed, and is implemented by a digital computer program that is based on a digital simulation of the system. The program can be integrated into existing digital simulations of a system.

  1. Controlling qubit drift by recycling error correction syndromes

    NASA Astrophysics Data System (ADS)

    Blume-Kohout, Robin

    2015-03-01

    Physical qubits are susceptible to systematic drift, above and beyond the stochastic Markovian noise that motivates quantum error correction. This parameter drift must be compensated - if it is ignored, error rates will rise to intolerable levels - but compensation requires knowing the parameters' current value, which appears to require halting experimental work to recalibrate (e.g. via quantum tomography). Fortunately, this is untrue. I show how to perform on-the-fly recalibration on the physical qubits in an error correcting code, using only information from the error correction syndromes. The algorithm for detecting and compensating drift is very simple - yet, remarkably, when used to compensate Brownian drift in the qubit Hamiltonian, it achieves a stabilized error rate very close to the theoretical lower bound. Against 1/f noise, it is less effective only because 1/f noise is (like white noise) dominated by high-frequency fluctuations that are uncompensatable. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE

  2. Continuous quantum error correction as classical hybrid control

    NASA Astrophysics Data System (ADS)

    Mabuchi, Hideo

    2009-10-01

    The standard formulation of quantum error correction (QEC) comprises repeated cycles of error estimation and corrective intervention in the free dynamics of a qubit register. QEC can thus be seen as a form of feedback control, and it is of interest to seek a deeper understanding of the connection between the associated theories. Here we present a focused case study within this broad program, connecting continuous QEC with elements of hybrid control theory. We show that canonical methods of the latter engineering discipline, such as recursive filtering and dynamic programming approaches to solving the optimal control problem, can be applied fruitfully in the design of separated controller structures for quantum memories based on coding and continuous syndrome measurement.

  3. Controlling type-1 error rates in whole effluent toxicity testing

    SciTech Connect

    Smith, R.; Johnson, S.C.

    1995-12-31

    A form of variability, called the dose x test interaction, has been found to affect the variability of the mean differences from control in the statistical tests used to evaluate Whole Effluent Toxicity Tests for compliance purposes. Since the dose x test interaction is not included in these statistical tests, the assumed type-1 and type-2 error rates can be incorrect. The accepted type-1 error rate for these tests is 5%. Analysis of over 100 Ceriodaphnia, fathead minnow and sea urchin fertilization tests showed that when the test x dose interaction term was not included in the calculations the type-1 error rate was inflated to as high as 20%. In a compliance setting, this problem may lead to incorrect regulatory decisions. Statistical tests are proposed that properly incorporate the dose x test interaction variance.

  4. Attitude-Control Algorithm for Minimizing Maneuver Execution Errors

    NASA Technical Reports Server (NTRS)

    Acikmese, Behcet

    2008-01-01

    A G-RAC attitude-control algorithm is used to minimize maneuver execution error in a spacecraft with a flexible appendage when said spacecraft must induce translational momentum by firing (in open loop) large thrusters along a desired direction for a given period of time. The controller is dynamic with two integrators and requires measurement of only the angular position and velocity of the spacecraft. The global stability of the closed-loop system is guaranteed without having access to the states describing the dynamics of the appendage and with severe saturation in the available torque. Spacecraft apply open-loop thruster firings to induce a desired translational momentum with an extended appendage. This control algorithm will assist this maneuver by stabilizing the attitude dynamics around a desired orientation, and consequently minimize the maneuver execution errors.

  5. Anomaly and error detection in computerized materials control & accountability databases

    SciTech Connect

    Whiteson, R.; Hoffbauer, B.; Yarbro, T.F.

    1997-09-01

    Unites States Department of Energy sites use computerized material control and accountability (MC&A) systems to manage the large amounts of data necessary to control and account for their nuclear materials. Theft or diversion of materials from these sites would likely result in anomalies in the data, and erroneous information greatly reduces the value of the information to its users. Therefore, it is essential that MC&A data be periodically assessed for anomalies or errors. At Los Alamos National Laboratory, we have been developing expert systems to provide efficient, cost-effective, automated error and anomaly detection. Automated anomaly detection can provide assurance of the integrity of data, reduce inventory frequency, enhance assurance of physical inventory, detect errors in databases, and gain a better perspective on overall facility operations. The Automated MC&A Database Assessment Project is aimed at improving anomaly and error detection in MC&A databases and increasing confidence in the data. We are working with data from the Los Alamos Plutonium Facility and the Material Accountability and Safeguards System, the Facility`s near-real-time computerized nuclear material accountability and safeguards system. This paper describes progress in customizing the expert systems to the needs of the users of the data and reports on our results.

  6. Current approaches to punitive action for medication errors by boards of pharmacy.

    PubMed

    Holdsworth, Mark; Wittstrom, Kristina; Yeitrakis, Tiffany

    2013-04-01

    To increase disclosure of errors and lead to system improvements, publications recommend a nonpunitive approach to medication errors. To our knowledge there is no published information regarding the extent or bases on which boards of pharmacy invoke punitive action against pharmacists involved in medication errors. To determine how often and on what bases boards of pharmacy determine punitive action to be taken against pharmacists involved in medication error events. The policies, procedures, and practices regarding medication errors by pharmacists for 49 of the 50 US boards of pharmacy were reviewed by pharmacy students at the University of New Mexico as a Safe Medication Practices class assignment. Most boards of pharmacy invoke punitive action against pharmacists involved in medication errors. Most states do not have specific rules or regulations that stipulate errors as actual violations and most determinations are made on a case-by-case basis. The major determinants of punitive action were error severity, actual patient injury, patient complaints, and factors related to the pharmacist. The most common types of punitive action include license suspension, probation, or revocation, and fines. In at least 17 states, incarceration was also a possible punitive action. The most common bases for punitive action were to address public safety/health and public complaints. Despite the fact that punitive action is not recommended as best practice for addressing medication errors made by health care practitioners, most state boards of pharmacy use punitive measures against pharmacists involved in medication errors. Based on current recommendations, such actions would not be expected to lead to improvements in the health care system.

  7. Precision electronic speed controller for an alternating-current motor

    DOEpatents

    Bolie, V.W.

    A high precision controller for an alternating-current multi-phase electrical motor that is subject to a large inertial load. The controller was developed for controlling, in a neutron chopper system, a heavy spinning rotor that must be rotated in phase-locked synchronism with a reference pulse train that is representative of an ac power supply signal having a meandering line frequency. The controller includes a shaft revolution sensor which provides a feedback pulse train representative of the actual speed of the motor. An internal digital timing signal generator provides a reference signal which is compared with the feedback signal in a computing unit to provide a motor control signal. The motor control signal is a weighted linear sum of a speed error voltage, a phase error voltage, and a drift error voltage, each of which is computed anew with each revolution of the motor shaft. The speed error signal is generated by a novel vernier-logic circuit which is drift-free and highly sensitive to small speed changes. The phase error is also computed by digital logic, with adjustable sensitivity around a 0 mid-scale value. The drift error signal, generated by long-term counting of the phase error, is used to compensate for any slow changes in the average friction drag on the motor. An auxillary drift-byte status sensor prevents any disruptive overflow or underflow of the drift-error counter. An adjustable clocked-delay unit is inserted between the controller and the source of the reference pulse train to permit phase alignment of the rotor to any desired offset angle. The stator windings of the motor are driven by two amplifiers which are provided with input signals having the proper quadrature relationship by an exciter unit consisting of a voltage controlled oscillator, a binary counter, a pair of read-only memories, and a pair of digital-to-analog converters.

  8. Error message recording and reporting in the SLC control system

    SciTech Connect

    Spencer, N.; Bogart, J.; Phinney, N.; Thompson, K.

    1985-04-01

    Error or information messages that are signaled by control software either in the VAX host computer or the local microprocessor clusters are handled by a dedicated VAX process (PARANOIA). Messages are recorded on disk for further analysis and displayed at the appropriate console. Another VAX process (ERRLOG) can be used to sort, list and histogram various categories of messages. The functions performed by these processes and the algorithms used are discussed.

  9. Error control techniques for satellite and space communications

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.

    1991-01-01

    Research activities related to error control techniques for satellite and space communication are reported. Specific areas of research include: coding gains for bandwidth efficient codes, hardware implementation of a bandwidth efficient coding scheme for the Hubble Space Telescope, construction of long trellis codes for use with sequential decoding, performance analysis of multilevel trellis codes, and M-algorithm decoding of trellis codes. Each topic is discussed in a corresponding paper that appears in the appendices.

  10. Nonlinear Multiscale Transformations: From Synchronization to Error Control

    DTIC Science & Technology

    2001-07-01

    Donat Dept. Matematica Aplicada, University of Valencia, Spain. arandiga@uv. es donat uv. es Abstract Data-dependent interpolatory techniques can be used...image compression and their ability to effectively control the global error due to compression. 1 Introduction Multiscale transformations are being...a linear operator and DiPj = Ivj-’, i.e., the identity operator on the lower resolution level represented by Vi- 1 . For all practical purposes, Vi can

  11. Coordinated joint motion control system with position error correction

    DOEpatents

    Danko, George [Reno, NV

    2011-11-22

    Disclosed are an articulated hydraulic machine supporting, control system and control method for same. The articulated hydraulic machine has an end effector for performing useful work. The control system is capable of controlling the end effector for automated movement along a preselected trajectory. The control system has a position error correction system to correct discrepancies between an actual end effector trajectory and a desired end effector trajectory. The correction system can employ one or more absolute position signals provided by one or more acceleration sensors supported by one or more movable machine elements. Good trajectory positioning and repeatability can be obtained. A two-joystick controller system is enabled, which can in some cases facilitate the operator's task and enhance their work quality and productivity.

  12. Coordinated joint motion control system with position error correction

    DOEpatents

    Danko, George L.

    2016-04-05

    Disclosed are an articulated hydraulic machine supporting, control system and control method for same. The articulated hydraulic machine has an end effector for performing useful work. The control system is capable of controlling the end effector for automated movement along a preselected trajectory. The control system has a position error correction system to correct discrepancies between an actual end effector trajectory and a desired end effector trajectory. The correction system can employ one or more absolute position signals provided by one or more acceleration sensors supported by one or more movable machine elements. Good trajectory positioning and repeatability can be obtained. A two joystick controller system is enabled, which can in some cases facilitate the operator's task and enhance their work quality and productivity.

  13. Unequal error control scheme for dimmable visible light communication systems

    NASA Astrophysics Data System (ADS)

    Deng, Keyan; Yuan, Lei; Wan, Yi; Li, Huaan

    2017-01-01

    Visible light communication (VLC), which has the advantages of a very large bandwidth, high security, and freedom from license-related restrictions and electromagnetic-interference, has attracted much interest. Because a VLC system simultaneously performs illumination and communication functions, dimming control, efficiency, and reliable transmission are significant and challenging issues of such systems. In this paper, we propose a novel unequal error control (UEC) scheme in which expanding window fountain (EWF) codes in an on-off keying (OOK)-based VLC system are used to support different dimming target values. To evaluate the performance of the scheme for various dimming target values, we apply it to H.264 scalable video coding bitstreams in a VLC system. The results of the simulations that are performed using additive white Gaussian noises (AWGNs) with different signal-to-noise ratios (SNRs) are used to compare the performance of the proposed scheme for various dimming target values. It is found that the proposed UEC scheme enables earlier base layer recovery compared to the use of the equal error control (EEC) scheme for different dimming target values and therefore afford robust transmission for scalable video multicast over optical wireless channels. This is because of the unequal error protection (UEP) and unequal recovery time (URT) of the EWF code in the proposed scheme.

  14. Ordering genes: controlling the decision-error probabilities.

    PubMed Central

    Rogatko, A; Zacks, S

    1993-01-01

    Determination of the relative gene order on chromosomes is of critical importance in the construction of human gene maps. In this paper we develop a sequential algorithm for gene ordering. We start by comparing three sequential procedures to order three genes on the basis of Bayesian posterior probabilities, maximum-likelihood ratio, and minimal recombinant class. In the second part of the paper we extend sequential procedure based on the posterior probabilities to the general case of g genes. We present a theorem that states that the predicted average probability of committing a decision error, associated with a Bayesian sequential procedure that accepts the hypothesis of a gene-order configuration with posterior probability equal to or greater than pi *, is smaller than 1 - pi *. This theorem holds irrespective of the number of genes, the genetic model, and the source of genetic information. The theorem is an extension of a classical result of Wald, concerning the sum of the actual and the nominal error probabilities in the sequential probability ratio test of two hypotheses. A stepwise strategy for ordering a large number of genes, with control over the decision-error probabilities, is discussed. An asymptotic approximation is provided, which facilitates the calculations with existing computer software for gene mapping, of the posterior probabilities of an order and the error probabilities. We illustrate with some simulations that the stepwise ordering is an efficient procedure. PMID:8488844

  15. Artificial neural network implementation of a near-ideal error prediction controller

    NASA Technical Reports Server (NTRS)

    Mcvey, Eugene S.; Taylor, Lynore Denise

    1992-01-01

    A theory has been developed at the University of Virginia which explains the effects of including an ideal predictor in the forward loop of a linear error-sampled system. It has been shown that the presence of this ideal predictor tends to stabilize the class of systems considered. A prediction controller is merely a system which anticipates a signal or part of a signal before it actually occurs. It is understood that an exact prediction controller is physically unrealizable. However, in systems where the input tends to be repetitive or limited, (i.e., not random) near ideal prediction is possible. In order for the controller to act as a stability compensator, the predictor must be designed in a way that allows it to learn the expected error response of the system. In this way, an unstable system will become stable by including the predicted error in the system transfer function. Previous and current prediction controller include pattern recognition developments and fast-time simulation which are applicable to the analysis of linear sampled data type systems. The use of pattern recognition techniques, along with a template matching scheme, has been proposed as one realizable type of near-ideal prediction. Since many, if not most, systems are repeatedly subjected to similar inputs, it was proposed that an adaptive mechanism be used to 'learn' the correct predicted error response. Once the system has learned the response of all the expected inputs, it is necessary only to recognize the type of input with a template matching mechanism and then to use the correct predicted error to drive the system. Suggested here is an alternate approach to the realization of a near-ideal error prediction controller, one designed using Neural Networks. Neural Networks are good at recognizing patterns such as system responses, and the back-propagation architecture makes use of a template matching scheme. In using this type of error prediction, it is assumed that the system error

  16. Run-to-run CD error analysis and control monitoring of effective dose and focus

    NASA Astrophysics Data System (ADS)

    Asano, Masafumi; Fujisawa, Tadahito; Izuha, Kyoko; Inoue, Soichi

    2003-05-01

    We have developed in-line dose and focus monitoring techniques for the detailed analysis of critical dimension error and accurate process control. From exposed wafers, effective does and focus are measured with specificed monitor marks built on a reticle. The contributions of effective dose and focus to critical dimension error on device chips were clarified in a fabrication proces of 110 nm isolated pattern with a KrF scanner. The critical dimensions error was described as a function of effective dose and focus, which include various process fluctuations. We could determine whether current exposure settings such as dose input and focus input were adequate or not. Based on the experimental data, we estimated the benefit of simultaneous Run-to-Run control of dose and focus. The estimation clarifies that it realizes total critical dimension control including Run-to-Run and intra-Run.

  17. A wire spark chamber capacitive readout system with low leakage current and small systematic error

    NASA Astrophysics Data System (ADS)

    Anderhub, H. B.; Boecklin, J.; von Gunten, H. P.; Koenig, H.; Le Coultre, P.; Makowiecki, D.; Seiler, P. G.

    1983-02-01

    A wire spark chamber capacitive readout system with analog FET switch multiplexing and CAMAC interface is described. Two wire planes per chamber are read out. The information of each plane is sequentially digitized in one ADC. This and the low leakage current of the FET switches guarantee a small systematic error of the measurement of the spark position.

  18. Field errors introduced by eddy currents in Fermilab main injector magnets

    SciTech Connect

    Walbridge, D.G.C.; Brown, B.C.; Dinanco, J.B.; Sharoran, S.A.; Sim, J.W.

    1997-10-01

    The Fermilab Main Injector ramps from 8 GeV to 120 GeV in about half a second. The rapidly changing magnetic field induces eddy currents in the stainless steel vacuum tubes, which in turn produce error fields that can affect the beam. Field calculations and measurements are presented for the dipole and quadrupole magnets.

  19. Cognitive control of conscious error awareness: error awareness and error positivity (Pe) amplitude in moderate-to-severe traumatic brain injury (TBI)

    PubMed Central

    Logan, Dustin M.; Hill, Kyle R.; Larson, Michael J.

    2015-01-01

    Poor awareness has been linked to worse recovery and rehabilitation outcomes following moderate-to-severe traumatic brain injury (M/S TBI). The error positivity (Pe) component of the event-related potential (ERP) is linked to error awareness and cognitive control. Participants included 37 neurologically healthy controls and 24 individuals with M/S TBI who completed a brief neuropsychological battery and the error awareness task (EAT), a modified Stroop go/no-go task that elicits aware and unaware errors. Analyses compared between-group no-go accuracy (including accuracy between the first and second halves of the task to measure attention and fatigue), error awareness performance, and Pe amplitude by level of awareness. The M/S TBI group decreased in accuracy and maintained error awareness over time; control participants improved both accuracy and error awareness during the course of the task. Pe amplitude was larger for aware than unaware errors for both groups; however, consistent with previous research on the Pe and TBI, there were no significant between-group differences for Pe amplitudes. Findings suggest possible attention difficulties and low improvement of performance over time may influence specific aspects of error awareness in M/S TBI. PMID:26217212

  20. Cognitive control of conscious error awareness: error awareness and error positivity (Pe) amplitude in moderate-to-severe traumatic brain injury (TBI).

    PubMed

    Logan, Dustin M; Hill, Kyle R; Larson, Michael J

    2015-01-01

    Poor awareness has been linked to worse recovery and rehabilitation outcomes following moderate-to-severe traumatic brain injury (M/S TBI). The error positivity (Pe) component of the event-related potential (ERP) is linked to error awareness and cognitive control. Participants included 37 neurologically healthy controls and 24 individuals with M/S TBI who completed a brief neuropsychological battery and the error awareness task (EAT), a modified Stroop go/no-go task that elicits aware and unaware errors. Analyses compared between-group no-go accuracy (including accuracy between the first and second halves of the task to measure attention and fatigue), error awareness performance, and Pe amplitude by level of awareness. The M/S TBI group decreased in accuracy and maintained error awareness over time; control participants improved both accuracy and error awareness during the course of the task. Pe amplitude was larger for aware than unaware errors for both groups; however, consistent with previous research on the Pe and TBI, there were no significant between-group differences for Pe amplitudes. Findings suggest possible attention difficulties and low improvement of performance over time may influence specific aspects of error awareness in M/S TBI.

  1. A new error control scheme for hybrid ARQ systems

    NASA Astrophysics Data System (ADS)

    Krishna, Hari; Morgera, Salvatore D.

    1987-10-01

    This paper introduces the concept of a generalized hybrid ARQ (GH-ARQ) scheme for adaptive error control in digital communication systems. This technique utilizes the redundant information available upon successive retransmissions in an efficient manner so as to provide high throughput during poor channel conditions. A new class of linear codes is proposed for the GH-ARQ system application. The main feature of this class of codes is that the encoder/decoder configuration does not change as the length of the code is varied. As a result, the receiver uses the same decoder for decoding the received information after every retransmission while the error correcting capability of the code increases, thereby leading to an improved performance and minimum complexity for the overall system implementation.

  2. Straight to the Source: Detecting Aggregate Objects in Astronomical Images with Proper Error Control

    PubMed Central

    Friedenberg, David A.; Genovese, Christopher R.

    2013-01-01

    The next generation of telescopes, coming on-line in the next decade, will acquire terabytes of image data each night. Collectively, these large images will contain billions of interesting objects, which astronomers call sources. One critical task for astronomers is to construct from the image data a detailed source catalog that gives the sky coordinates and other properties of all detected sources. The source catalog is the primary data product produced by most telescopes and serves as an important input for studies that build and test new astrophysical theories. To construct an accurate catalog, the sources must first be detected in the image. A variety of effective source detection algorithms exist in the astronomical literature, but few if any provide rigorous statistical control of error rates. A variety of multiple testing procedures exist in the statistical literature that can provide rigorous error control over pixelwise errors, but these do not provide control over errors at the level of sources, which is what astronomers need. In this paper, we propose a technique that is effective at source detection while providing rigorous control on source-wise error rates. We demonstrate our approach with data from the Chandra X-ray Observatory Satellite. Our method is competitive with existing astronomical methods, even finding two new sources that were missed by previous studies, while providing stronger performance guarantees and without requiring costly follow up studies that are commonly required with current techniques. PMID:24068849

  3. Straight to the Source: Detecting Aggregate Objects in Astronomical Images with Proper Error Control.

    PubMed

    Friedenberg, David A; Genovese, Christopher R

    2013-07-01

    The next generation of telescopes, coming on-line in the next decade, will acquire terabytes of image data each night. Collectively, these large images will contain billions of interesting objects, which astronomers call sources. One critical task for astronomers is to construct from the image data a detailed source catalog that gives the sky coordinates and other properties of all detected sources. The source catalog is the primary data product produced by most telescopes and serves as an important input for studies that build and test new astrophysical theories. To construct an accurate catalog, the sources must first be detected in the image. A variety of effective source detection algorithms exist in the astronomical literature, but few if any provide rigorous statistical control of error rates. A variety of multiple testing procedures exist in the statistical literature that can provide rigorous error control over pixelwise errors, but these do not provide control over errors at the level of sources, which is what astronomers need. In this paper, we propose a technique that is effective at source detection while providing rigorous control on source-wise error rates. We demonstrate our approach with data from the Chandra X-ray Observatory Satellite. Our method is competitive with existing astronomical methods, even finding two new sources that were missed by previous studies, while providing stronger performance guarantees and without requiring costly follow up studies that are commonly required with current techniques.

  4. Controlling your impulses: electrical stimulation of the human supplementary motor complex prevents impulsive errors.

    PubMed

    Spieser, Laure; van den Wildenberg, Wery; Hasbroucq, Thierry; Ridderinkhof, K Richard; Burle, Borís

    2015-02-18

    To err is human. However, an inappropriate urge does not always result in error. Impulsive errors thus entail both a motor system capture by an urge to act and a failed inhibition of that impulse. Here we show that neuromodulatory electrical stimulation of the supplementary motor complex in healthy humans leaves action urges unchanged but prevents them from turning into overt errors. Subjects performed a choice reaction-time task known to trigger impulsive responses, leading to fast errors that can be revealed by analyzing accuracy as a function of poststimulus time. Yet, such fast errors are only the tip of the iceberg: electromyography (EMG) revealed fast subthreshold muscle activation in the incorrect response hand in an even larger proportion of overtly correct trials, revealing covert response impulses not discernible in overt behavior. Analyzing both overt and covert response tendencies enables to gauge the ability to prevent these incorrect impulses from turning into overt action errors. Hyperpolarizing the supplementary motor complex using transcranial direct current stimulation (tDCS) preserves action impulses but prevents their behavioral expression. This new combination of detailed behavioral, EMG, and tDCS techniques clarifies the neurophysiology of impulse control, and may point to avenues for improving impulse control deficits in various neurologic and psychiatric disorders.

  5. Voltage controller/current limiter for ac

    NASA Technical Reports Server (NTRS)

    Wu, T. T.

    1980-01-01

    Circuit protects ac power systems for overload failures, limits power surge and short-circuit currents to 150 percent of steady state level, regulates ac output voltage, and soft starts loads. Limiter generates dc error signal in response to line fluctuations and dumps power when overload is reached. Device is inserted between ac source and load.

  6. Controlling motion prediction errors in radiotherapy with relevance vector machines.

    PubMed

    Dürichen, Robert; Wissel, Tobias; Schweikard, Achim

    2015-04-01

    Robotic radiotherapy can precisely ablate moving tumors when time latencies have been compensated. Recently, relevance vector machines (RVM), a probabilistic regression technique, outperformed six other prediction algorithms for respiratory compensation. The method has the distinct advantage that each predicted point is assumed to be drawn from a normal distribution. Second-order statistics, the predicted variance, were used to control RVM prediction error during a treatment and to construct hybrid prediction algorithms. First, the duty cycle and the precision were correlated to the variance by interrupting the treatment if the variance exceeds a threshold. Second, two hybrid algorithms based on the variance were developed, one consisting of multiple RVMs (HYB(RVM)) and the other of a combination between a wavelet-based least mean square algorithm (wLMS) and a RVM (HYB(wLMS-RVM)). The variance for different motion traces was analyzed to reveal a characteristic variance pattern which gives insight in what kind of prediction errors can be controlled by the variance. Limiting the variance by a threshold resulted in an increased precision with a decreased duty cycle. All hybrid algorithms showed an increased prediction accuracy compared to using only their individual algorithms. The best hybrid algorithm, HYB(RVM), can decrease the mean RMSE over all 304 motion traces from 0.18 mm for a linear RVM to 0.17 mm. The predicted variance was shown to be an efficient metric to control prediction errors, resulting in a more robust radiotherapy treatment. The hybrid algorithm HYB(RVM) could be translated to clinical practice. It does not require further parameters, can be completely parallelised and easily further extended.

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

    SciTech Connect

    Zhu Shiliang; Zanardi, Paolo

    2005-08-15

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

  8. Current pulse: can a production system reduce medical errors in health care?

    PubMed

    Printezis, Antonios; Gopalakrishnan, Mohan

    2007-01-01

    One of the reasons for rising health care costs is medical errors, a majority of which result from faulty systems and processes. Health care in the past has used process-based initiatives such as Total Quality Management, Continuous Quality Improvement, and Six Sigma to reduce errors. These initiatives to redesign health care, reduce errors, and improve overall efficiency and customer satisfaction have had moderate success. Current trend is to apply the successful Toyota Production System (TPS) to health care since its organizing principles have led to tremendous improvement in productivity and quality for Toyota and other businesses that have adapted them. This article presents insights on the effectiveness of TPS principles in health care and the challenges that lie ahead in successfully integrating this approach with other quality initiatives.

  9. Error field optimization in DIII-D using extremum seeking control

    NASA Astrophysics Data System (ADS)

    Lanctot, M. J.; Olofsson, K. E. J.; Capella, M.; Humphreys, D. A.; Eidietis, N.; Hanson, J. M.; Paz-Soldan, C.; Strait, E. J.; Walker, M. L.

    2016-07-01

    DIII-D experiments have demonstrated a new real-time approach to tokamak error field control based on maximizing the toroidal angular momentum. This approach uses extremum seeking control theory to optimize the error field in real time without inducing instabilities. Slowly-rotating n  =  1 fields (the dither), generated by external coils, are used to perturb the angular momentum, monitored in real-time using a charge-exchange spectroscopy diagnostic. Simple signal processing of the rotation measurements extracts information about the rotation gradient with respect to the control coil currents. This information is used to converge the control coil currents to a point that maximizes the toroidal angular momentum. The technique is well-suited for multi-coil, multi-harmonic error field optimizations in disruption sensitive devices as it does not require triggering locked tearing modes or plasma current disruptions. Control simulations highlight the importance of the initial search direction on the rate of the convergence, and identify future algorithm upgrades that may allow more rapid convergence that projects to convergence times in ITER on the order of tens of seconds.

  10. Error field optimization in DIII-D using extremum seeking control

    SciTech Connect

    Lanctot, M. J.; Olofsson, K. E. J.; Capella, M.; Humphreys, D. A.; Eidietis, N.; Hanson, J. M.; Paz-Soldan, C.; Strait, E. J.; Walker, M. L.

    2016-06-03

    A closed-loop error field control algorithm is implemented in the Plasma Control System of the DIII-D tokamak and used to identify optimal control currents during a single plasma discharge. The algorithm, based on established extremum seeking control theory, exploits the link in tokamaks between maximizing the toroidal angular momentum and minimizing deleterious non-axisymmetric magnetic fields. Slowly-rotating n = 1 fields (the dither), generated by external coils, are used to perturb the angular momentum, monitored in real-time using a charge-exchange spectroscopy diagnostic. Simple signal processing of the rotation measurements extracts information about the rotation gradient with respect to the control coil currents. This information is used to converge the control coil currents to a point that maximizes the toroidal angular momentum. The technique is well-suited for multi-coil, multi-harmonic error field optimizations in disruption sensitive devices as it does not require triggering locked tearing modes or plasma current disruptions. Control simulations highlight the importance of the initial search direction on the rate of the convergence, and identify future algorithm upgrades that may allow more rapid convergence that projects to convergence times in ITER on the order of tens of seconds.

  11. Error field optimization in DIII-D using extremum seeking control

    DOE PAGES

    Lanctot, M. J.; Olofsson, K. E. J.; Capella, M.; ...

    2016-06-03

    A closed-loop error field control algorithm is implemented in the Plasma Control System of the DIII-D tokamak and used to identify optimal control currents during a single plasma discharge. The algorithm, based on established extremum seeking control theory, exploits the link in tokamaks between maximizing the toroidal angular momentum and minimizing deleterious non-axisymmetric magnetic fields. Slowly-rotating n = 1 fields (the dither), generated by external coils, are used to perturb the angular momentum, monitored in real-time using a charge-exchange spectroscopy diagnostic. Simple signal processing of the rotation measurements extracts information about the rotation gradient with respect to the control coilmore » currents. This information is used to converge the control coil currents to a point that maximizes the toroidal angular momentum. The technique is well-suited for multi-coil, multi-harmonic error field optimizations in disruption sensitive devices as it does not require triggering locked tearing modes or plasma current disruptions. Control simulations highlight the importance of the initial search direction on the rate of the convergence, and identify future algorithm upgrades that may allow more rapid convergence that projects to convergence times in ITER on the order of tens of seconds.« less

  12. 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.

  13. Multivariable current control for electrically and magnetically coupled superconducting magnets

    SciTech Connect

    Owen, E.W.; Shimer, D.W.

    1985-02-08

    Superconducting magnet systems under construction and projected for the future contain magnets that are magnetically coupled and electrically connected with shared power supplies. A change in one power supply voltage affects all of the magnet currents. A current controller for these systems must be designed as a multivariable system. The paper describes a method, based on decoupling control, for the rational design of these systems. Dynamic decoupling is achieved by cross-feedback of the measured currents. A network of gains at the input decouples the system statically and eliminates the steady-state error. Errors are then due to component variations. The method has been applied to the magnet system of the MFTF-B, at the Lawrence Livermore National Laboratory.

  14. Current Concepts in Conception Control

    PubMed Central

    Ringrose, C. A. Douglas

    1963-01-01

    The progressive increase in world population has become a most urgent global problem in recent years. Man has, however, been interested in controlling his reproductivity at the family level for many centuries. Historical aspects of this saga are reviewed. The modern era of conception control was ushered in by Makepeace et al. in 1937 when ovulation inhibition by progesterone was demonstrated. Confirmation of this by Pincus and associates, and development of the potent oral progestational agents, the 19-norsteroids, have made efficient reliable contraception a reality. Experience with one of these agents (Ortho-Novum, 2 mg.) in 115 patients through 805 cycles is presented. Conception control was 100% effective at this dosage. Side effects were minimal. Only three of the women discontinued the tablets because of these effects. All but five in this group of 115 preferred the oral contraceptives to methods previously employed. PMID:13973987

  15. Current approaches to myopia control.

    PubMed

    Leo, Seo Wei

    2017-05-01

    Myopia is a global problem, being particularly prevalent in the urban areas of east and southeast Asia. In addition to the direct economic and social burdens, associated ocular complications may lead to substantial vision loss. With prevalence of myopia above 80% and high myopia over 20%, it is crucial to control myopia. The aim of this review to is provide an update on the interventions to slow the onset of myopia and retard its progression. The epidemic of myopia is characterized by increasingly early onset, combined with high myopia progression rates. There are two pathways for myopia control: firstly to slow the onset of myopia and secondly to reduce or prevent progression. Increased time outdoors can reduce the onset of myopia. Atropine 0.01% dose offers an appropriate risk-benefit ratio, with no clinically significant visual side effects balanced against a significant 50% reduction in myopia progression. Orthokeratology contact lenses can slow axial length elongation, but infective keratitis is a risk. Peripheral defocussing lenses may both have a role in slowing myopic progression in a subset of children and further help our understanding of the physiologic control of ocular growth. Myopia control can be achieved by slowing the onset of myopia, which now appears to be possible through increasing time outdoors and slowing the progression of myopia with interventions like atropine and orthokeratology.

  16. Trends in health information technology safety: from technology-induced errors to current approaches for ensuring technology safety.

    PubMed

    Borycki, Elizabeth

    2013-06-01

    Health information technology (HIT) research findings suggested that new healthcare technologies could reduce some types of medical errors while at the same time introducing classes of medical errors (i.e., technology-induced errors). Technology-induced errors have their origins in HIT, and/or HIT contribute to their occurrence. The objective of this paper is to review current trends in the published literature on HIT safety. A review and synthesis of the medical and life sciences literature focusing on the area of technology-induced error was conducted. There were four main trends in the literature on technology-induced error. The following areas were addressed in the literature: definitions of technology-induced errors; models, frameworks and evidence for understanding how technology-induced errors occur; a discussion of monitoring; and methods for preventing and learning about technology-induced errors. The literature focusing on technology-induced errors continues to grow. Research has focused on the defining what an error is, models and frameworks used to understand these new types of errors, monitoring of such errors and methods that can be used to prevent these errors. More research will be needed to better understand and mitigate these types of errors.

  17. Trends in Health Information Technology Safety: From Technology-Induced Errors to Current Approaches for Ensuring Technology Safety

    PubMed Central

    2013-01-01

    Objectives Health information technology (HIT) research findings suggested that new healthcare technologies could reduce some types of medical errors while at the same time introducing classes of medical errors (i.e., technology-induced errors). Technology-induced errors have their origins in HIT, and/or HIT contribute to their occurrence. The objective of this paper is to review current trends in the published literature on HIT safety. Methods A review and synthesis of the medical and life sciences literature focusing on the area of technology-induced error was conducted. Results There were four main trends in the literature on technology-induced error. The following areas were addressed in the literature: definitions of technology-induced errors; models, frameworks and evidence for understanding how technology-induced errors occur; a discussion of monitoring; and methods for preventing and learning about technology-induced errors. Conclusions The literature focusing on technology-induced errors continues to grow. Research has focused on the defining what an error is, models and frameworks used to understand these new types of errors, monitoring of such errors and methods that can be used to prevent these errors. More research will be needed to better understand and mitigate these types of errors. PMID:23882411

  18. Deciphering the genetic regulatory code using an inverse error control coding framework.

    SciTech Connect

    Rintoul, Mark Daniel; May, Elebeoba Eni; Brown, William Michael; Johnston, Anna Marie; Watson, Jean-Paul

    2005-03-01

    We have found that developing a computational framework for reconstructing error control codes for engineered data and ultimately for deciphering genetic regulatory coding sequences is a challenging and uncharted area that will require advances in computational technology for exact solutions. Although exact solutions are desired, computational approaches that yield plausible solutions would be considered sufficient as a proof of concept to the feasibility of reverse engineering error control codes and the possibility of developing a quantitative model for understanding and engineering genetic regulation. Such evidence would help move the idea of reconstructing error control codes for engineered and biological systems from the high risk high payoff realm into the highly probable high payoff domain. Additionally this work will impact biological sensor development and the ability to model and ultimately develop defense mechanisms against bioagents that can be engineered to cause catastrophic damage. Understanding how biological organisms are able to communicate their genetic message efficiently in the presence of noise can improve our current communication protocols, a continuing research interest. Towards this end, project goals include: (1) Develop parameter estimation methods for n for block codes and for n, k, and m for convolutional codes. Use methods to determine error control (EC) code parameters for gene regulatory sequence. (2) Develop an evolutionary computing computational framework for near-optimal solutions to the algebraic code reconstruction problem. Method will be tested on engineered and biological sequences.

  19. A concatenated coded modulation scheme for error control

    NASA Technical Reports Server (NTRS)

    Kasami, Tadao; Takata, Toyoo; Fujiwara, Toru; Lin, Shu

    1990-01-01

    A concatenated coded modulation scheme for error control in data communications is presented. The scheme is achieved by concatenating a Reed-Solomon outer code and a bandwidth efficient block inner code for M-ary PSK modulation. Error performance of the scheme is analyzed for an AWGN channel. It is shown that extremely high reliability can be attained by using a simple M-ary PSK modulation inner code and relatively powerful Reed-Solomon outer code. Furthermore, if an inner code of high effective rate is used, the bandwidth expansion required by the scheme due to coding will be greatly reduced. The proposed scheme is particularly effective for high speed satellite communications for large file transfer where high reliability is required. Also presented is a simple method for constructing block codes for M-ary PSK modulation. Some short M-ary PSK codes with good minimum squared Euclidean distance are constructed. These codes have trellis structure and hence can be decoded with a soft-decision Viterbi decoding algorithm.

  20. A concatenated coded modulation scheme for error control

    NASA Technical Reports Server (NTRS)

    Kasami, Tadao; Lin, Shu

    1988-01-01

    A concatenated coded modulation scheme for error control in data communications is presented. The scheme is achieved by concatenating a Reed-Solomon outer code and a bandwidth efficient block inner code for M-ary PSK modulation. Error performance of the scheme is analyzed for an AWGN channel. It is shown that extremely high reliability can be attained by using a simple M-ary PSK modulation inner code and relatively powerful Reed-Solomon outer code. Furthermore, if an inner code of high effective rate is used, the bandwidth expansion required by the scheme due to coding will be greatly reduced. The proposed scheme is particularly effective for high speed satellite communication for large file transfer where high reliability is required. Also presented is a simple method for constructing block codes for M-ary PSK modulation. Some short M-ary PSK codes with good minimum squared Euclidean distance are constructed. These codes have trellis structure and hence can be decoded with a soft decision Viterbi decoding algorithm.

  1. A concatenated coded modulation scheme for error control (addition 2)

    NASA Technical Reports Server (NTRS)

    Lin, Shu

    1988-01-01

    A concatenated coded modulation scheme for error control in data communications is described. The scheme is achieved by concatenating a Reed-Solomon outer code and a bandwidth efficient block inner code for M-ary PSK modulation. Error performance of the scheme is analyzed for an AWGN channel. It is shown that extremely high reliability can be attained by using a simple M-ary PSK modulation inner code and a relatively powerful Reed-Solomon outer code. Furthermore, if an inner code of high effective rate is used, the bandwidth expansion required by the scheme due to coding will be greatly reduced. The proposed scheme is particularly effective for high-speed satellite communications for large file transfer where high reliability is required. This paper also presents a simple method for constructing block codes for M-ary PSK modulation. Some short M-ary PSK codes with good minimum squared Euclidean distance are constructed. These codes have trellis structure and hence can be decoded with a soft-decision Viterbi decoding algorithm. Furthermore, some of these codes are phase invariant under multiples of 45 deg rotation.

  2. Carrier Phase Error Detection Method and Synchronization Control of Parallel-Connected PWM Inverters without Signal Line

    NASA Astrophysics Data System (ADS)

    Kohara, Tatsuya; Noguchi, Toshihiko; Kondo, Seiji

    In recent years, parallel-operation of inverters is employed to increase reliability and capacity in an uninterruptible power supply (UPS) system. A phase error in PWM carrier-signals of each inverter causes high frequency loop current between inverters. Therefore, the PWM carrier-signal of each inverter should be adjusted in phase. This paper proposes a detection method of phase error in PWM carrier-signal and its application to synchronization control for parallel-connected inverters. A simple definite-integral circuit achieves the detection of carrier phase error from high frequency loop current using no signal line between inverters. The detected carrier phase error is applied to synchronize the PWM carrier-signal through a PI-compensator, and then the high frequency loop current can be suppressed. Several experimental test-results show the validity of the proposed detection method and synchronization control.

  3. Variable current speed controller for eddy current motors

    DOEpatents

    Gerth, H.L.; Bailey, J.M.; Casstevens, J.M.; Dixon, J.H.; Griffith, B.O.; Igou, R.E.

    1982-03-12

    A speed control system for eddy current motors is provided in which the current to the motor from a constant frequency power source is varied by comparing the actual motor speed signal with a setpoint speed signal to control the motor speed according to the selected setpoint speed. A three-phase variable voltage autotransformer is provided for controlling the voltage from a three-phase power supply. A corresponding plurality of current control resistors is provided in series with each phase of the autotransformer output connected to inputs of a three-phase motor. Each resistor is connected in parallel with a set of normally closed contacts of plurality of relays which are operated by control logic. A logic circuit compares the selected speed with the actual motor speed obtained from a digital tachometer monitoring the motor spindle speed and operated the relays to add or substract resistance equally in each phase of the motor input to vary the motor current to control the motor at the selected speed.

  4. Testing and error analysis of a real-time controller

    NASA Technical Reports Server (NTRS)

    Savolaine, C. G.

    1983-01-01

    Inexpensive ways to organize and conduct system testing that were used on a real-time satellite network control system are outlined. This system contains roughly 50,000 lines of executable source code developed by a team of eight people. For a small investment of staff, the system was thoroughly tested, including automated regression testing, before field release. Detailed records were kept for fourteen months, during which several versions of the system were written. A separate testing group was not established, but testing itself was structured apart from the development process. The errors found during testing are examined by frequency per subsystem by size and complexity as well as by type. The code was released to the user in March, 1983. To date, only a few minor problems found with the system during its pre-service testing and user acceptance has been good.

  5. Testing and error analysis of a real-time controller

    NASA Technical Reports Server (NTRS)

    Savolaine, C. G.

    1983-01-01

    Inexpensive ways to organize and conduct system testing that were used on a real-time satellite network control system are outlined. This system contains roughly 50,000 lines of executable source code developed by a team of eight people. For a small investment of staff, the system was thoroughly tested, including automated regression testing, before field release. Detailed records were kept for fourteen months, during which several versions of the system were written. A separate testing group was not established, but testing itself was structured apart from the development process. The errors found during testing are examined by frequency per subsystem by size and complexity as well as by type. The code was released to the user in March, 1983. To date, only a few minor problems found with the system during its pre-service testing and user acceptance has been good.

  6. An Optimal Current Observer for Predictive Current Controlled Buck DC-DC Converters

    PubMed Central

    Min, Run; Chen, Chen; Zhang, Xiaodong; Zou, Xuecheng; Tong, Qiaoling; Zhang, Qiao

    2014-01-01

    In digital current mode controlled DC-DC converters, conventional current sensors might not provide isolation at a minimized price, power loss and size. Therefore, a current observer which can be realized based on the digital circuit itself, is a possible substitute. However, the observed current may diverge due to the parasitic resistors and the forward conduction voltage of the diode. Moreover, the divergence of the observed current will cause steady state errors in the output voltage. In this paper, an optimal current observer is proposed. It achieves the highest observation accuracy by compensating for all the known parasitic parameters. By employing the optimal current observer-based predictive current controller, a buck converter is implemented. The converter has a convergently and accurately observed inductor current, and shows preferable transient response than the conventional voltage mode controlled converter. Besides, costs, power loss and size are minimized since the strategy requires no additional hardware for current sensing. The effectiveness of the proposed optimal current observer is demonstrated experimentally. PMID:24854061

  7. Measurement of Turbulence with Acoustic Doppler Current Profilers - Sources of Error and Laboratory Results

    USGS Publications Warehouse

    Nystrom, E.A.; Oberg, K.A.; Rehmann, C.R.; ,

    2002-01-01

    Acoustic Doppler current profilers (ADCPs) provide a promising method for measuring surface-water turbulence because they can provide data from a large spatial range in a relatively short time with relative ease. Some potential sources of errors in turbulence measurements made with ADCPs include inaccuracy of Doppler-shift measurements, poor temporal and spatial measurement resolution, and inaccuracy of multi-dimensional velocities resolved from one-dimensional velocities measured at separate locations. Results from laboratory measurements of mean velocity and turbulence statistics made with two pulse-coherent ADCPs in 0.87 meters of water are used to illustrate several of inherent sources of error in ADCP turbulence measurements. Results show that processing algorithms and beam configurations have important effects on turbulence measurements. ADCPs can provide reasonable estimates of many turbulence parameters; however, the accuracy of turbulence measurements made with commercially available ADCPs is often poor in comparison to standard measurement techniques.

  8. The role of movement errors in modifying spatiotemporal gait asymmetry post stroke: a randomized controlled trial.

    PubMed

    Lewek, Michael D; Braun, Carty H; Wutzke, Clint; Giuliani, Carol

    2017-07-01

    Current rehabilitation to improve gait symmetry following stroke is based on one of two competing motor learning strategies: minimizing or augmenting symmetry errors. We sought to determine which of those motor learning strategies best improves overground spatiotemporal gait symmetry. Randomized controlled trial. Rehabilitation research lab. In all, 47 participants (59 ± 12 years old) with chronic hemiparesis post stroke and spatiotemporal gait asymmetry were randomized to error augmentation, error minimization, or conventional treadmill training (control) groups. To augment or minimize asymmetry on a step-by-step basis, we developed a responsive, "closed-loop" control system, using a split-belt instrumented treadmill that continuously adjusted the difference in belt speeds to be proportional to the patient's current asymmetry. Overground spatiotemporal asymmetries and gait speeds were collected prior to and following 18 training sessions. Step length asymmetry reduced after training, but stance time did not. There was no group × time interaction. Gait speed improved after training, but was not affected by type of asymmetry, or group. Of those who trained to modify step length asymmetry, there was a moderately strong linear relationship between the change in step length asymmetry and the change in gait speed. Augmenting errors was not superior to minimizing errors or providing only verbal feedback during conventional treadmill walking. Therefore, the use of verbal feedback to target spatiotemporal asymmetry, which was common to all participants, appears to be sufficient to reduce step length asymmetry. Alterations in stance time asymmetry were not elicited in any group.

  9. Nonlinear signal-based control with an error feedback action for nonlinear substructuring control

    NASA Astrophysics Data System (ADS)

    Enokida, Ryuta; Kajiwara, Koichi

    2017-01-01

    A nonlinear signal-based control (NSBC) method utilises the 'nonlinear signal' that is obtained from the outputs of a controlled system and its linear model under the same input signal. Although this method has been examined in numerical simulations of nonlinear systems, its application in physical experiments has not been studied. In this paper, we study an application of NSBC in physical experiments and incorporate an error feedback action into the method to minimise the error and enhance the feasibility in practice. Focusing on NSBC in substructure testing methods, we propose nonlinear substructuring control (NLSC), that is a more general form of linear substructuring control (LSC) developed for dynamical substructured systems. In this study, we experimentally and numerically verified the proposed NLSC via substructuring tests on a rubber bearing used in base-isolated structures. In the examinations, NLSC succeeded in gaining accurate results despite significant nonlinear hysteresis and unknown parameters in the substructures. The nonlinear signal feedback action in NLSC was found to be notably effective in minimising the error caused by nonlinearity or unknown properties in the controlled system. In addition, the error feedback action in NLSC was found to be essential for maintaining stability. A stability analysis based on the Nyquist criterion, which is used particularly for linear systems, was also found to be efficient for predicting the instability conditions of substructuring tests with NLSC and useful for the error feedback controller design.

  10. LCL Current Control Loop Stability Design

    NASA Astrophysics Data System (ADS)

    Delepaut, Christophe; Kuremyr, Tobias; Martin, Manuel; Tonicello, Ferdinando

    2014-08-01

    Latching Current Limiters include a control loop meant at limiting the current in case of downstream failure. Such current control loop consists typically of a simple proportional feedback gain from a current measurement shunt resistance and may result in very limited phase margin for specified operating conditions. The present paper investigates the combination of a proportional and derivative feedback to mitigate the lack of stability margin, providing a comprehensive overview on designing Latching Current Limiters for stability. For illustration purpose, a LCL based on radiation hardened ITAR free components is considered. A breadboard has been manufactured and the reported phase margin measurements demonstrate performances in line with the analytic results.

  11. Precision electronic speed controller for an alternating-current

    DOEpatents

    Bolie, Victor W.

    1988-01-01

    A high precision controller for an alternating-current multi-phase electrical motor that is subject to a large inertial load. The controller was developed for and is particularly suitable for controlling, in a neutron chopper system, a heavy spinning rotor that must be rotated in phase-locked synchronism with a reference pulse train that is representative of an ac power supply signal having a meandering line frequency. The controller includes a shaft revolution sensor which provides a feedback pulse train representative of the actual speed of the motor. An internal digital timing signal generator provides a reference signal which is compared with the feedback signal in a computing unit to provide a motor control signal. In the preferred embodiment, the motor control signal is a weighted linear sum of a speed error voltage, a phase error voltage, and a drift error voltage, each of which is computed anew with each revolution of the motor shaft. The stator windings of the motor are driven by two amplifiers which are provided with input signals having the proper quadrature relationship by an exciter unit consisting of a voltage controlled oscillator, a binary counter, a pair of readonly memories, and a pair of digital-to-analog converters.

  12. Striatal prediction errors support dynamic control of declarative memory decisions

    PubMed Central

    Scimeca, Jason M.; Katzman, Perri L.; Badre, David

    2016-01-01

    Adaptive memory requires context-dependent control over how information is retrieved, evaluated and used to guide action, yet the signals that drive adjustments to memory decisions remain unknown. Here we show that prediction errors (PEs) coded by the striatum support control over memory decisions. Human participants completed a recognition memory test that incorporated biased feedback to influence participants' recognition criterion. Using model-based fMRI, we find that PEs—the deviation between the outcome and expected value of a memory decision—correlate with striatal activity and predict individuals' final criterion. Importantly, the striatal PEs are scaled relative to memory strength rather than the expected trial outcome. Follow-up experiments show that the learned recognition criterion transfers to free recall, and targeting biased feedback to experimentally manipulate the magnitude of PEs influences criterion consistent with PEs scaled relative to memory strength. This provides convergent evidence that declarative memory decisions can be regulated via striatally mediated reinforcement learning signals. PMID:27713407

  13. Error correction, sensory prediction, and adaptation in motor control.

    PubMed

    Shadmehr, Reza; Smith, Maurice A; Krakauer, John W

    2010-01-01

    Motor control is the study of how organisms make accurate goal-directed movements. Here we consider two problems that the motor system must solve in order to achieve such control. The first problem is that sensory feedback is noisy and delayed, which can make movements inaccurate and unstable. The second problem is that the relationship between a motor command and the movement it produces is variable, as the body and the environment can both change. A solution is to build adaptive internal models of the body and the world. The predictions of these internal models, called forward models because they transform motor commands into sensory consequences, can be used to both produce a lifetime of calibrated movements, and to improve the ability of the sensory system to estimate the state of the body and the world around it. Forward models are only useful if they produce unbiased predictions. Evidence shows that forward models remain calibrated through motor adaptation: learning driven by sensory prediction errors.

  14. Error Types and Error Positions in Neglect Dyslexia: Comparative Analyses in Neglect Patients and Healthy Controls

    ERIC Educational Resources Information Center

    Weinzierl, Christiane; Kerkhoff, Georg; van Eimeren, Lucia; Keller, Ingo; Stenneken, Prisca

    2012-01-01

    Unilateral spatial neglect frequently involves a lateralised reading disorder, neglect dyslexia (ND). Reading of single words in ND is characterised by left-sided omissions and substitutions of letters. However, it is unclear whether the distribution of error types and positions within a word shows a unique pattern of ND when directly compared to…

  15. Motor control: correcting errors and learning from mistakes.

    PubMed

    Miall, Chris

    2010-07-27

    How do we learn from errors during complex movement tasks with redundancy? A new study shows that ambiguous mistakes in bimanual movements are corrected by the non-dominant hand, and responsibility for the error is assumed to fall to the effector with a recent history of poor performance.

  16. Fault tolerance control of phase current in permanent magnet synchronous motor control system

    NASA Astrophysics Data System (ADS)

    Chen, Kele; Chen, Ke; Chen, Xinglong; Li, Jinying

    2014-08-01

    As the Photoelectric tracking system develops from earth based platform to all kinds of moving platform such as plane based, ship based, car based, satellite based and missile based, the fault tolerance control system of phase current sensor is studied in order to detect and control of failure of phase current sensor on a moving platform. By using a DC-link current sensor and the switching state of the corresponding SVPWM inverter, the failure detection and fault control of three phase current sensor is achieved. Under such conditions as one failure, two failures and three failures, fault tolerance is able to be controlled. The reason why under the method, there exists error between fault tolerance control and actual phase current, is analyzed, and solution to weaken the error is provided. The experiment based on permanent magnet synchronous motor system is conducted, and the method is proven to be capable of detecting the failure of phase current sensor effectively and precisely, and controlling the fault tolerance simultaneously. With this method, even though all the three phase current sensors malfunction, the moving platform can still work by reconstructing the phase current of the motor.

  17. A cascaded error control coding scheme for space and satellite communication

    NASA Technical Reports Server (NTRS)

    Lin, Shu; Kasami, Tadao; Fujiwara, Tohru; Takata, Toyoo

    1986-01-01

    An error control coding scheme for space and satellite communications is presented. The scheme is attained by cascading two codes, the inner and outer codes. Error performance of the scheme is analyzed. It is shown that, if the inner and outer codes are chosen properly, extremely high reliability can be achieved even for a high channel bit-error-rate. Several exmple schemes are studied. One of the example schemes is proposed to NASA for satellite or spacecraft downlink error control.

  18. Development of a Transmission Error Model and an Error Control Model

    DTIC Science & Technology

    1975-05-01

    of the F Channel," IEEE Trans. on Communications Technology, Vol. COM-17, Feb. 1969, pp. 24-32. 8. S. Tsai, "Analytic Method for Evaluating Error...the Z P results for 864 message sequences. For the two otherg codes evaluated in the present study using his method , the results seem to fall bet.een...although related, method . Agreement between the results of Johnson and those obtained with the Z P &Jlgorithm is good. g 73 The LP algorithm has been used

  19. Improved Conflict Detection for Reducing Operational Errors in Air Traffic Control

    NASA Technical Reports Server (NTRS)

    Paielli, Russell A.; Erzberger, Hainz

    2003-01-01

    An operational error is an incident in which an air traffic controller allows the separation between two aircraft to fall below the minimum separation standard. The rates of such errors in the US have increased significantly over the past few years. This paper proposes new detection methods that can help correct this trend by improving on the performance of Conflict Alert, the existing software in the Host Computer System that is intended to detect and warn controllers of imminent conflicts. In addition to the usual trajectory based on the flight plan, a "dead-reckoning" trajectory (current velocity projection) is also generated for each aircraft and checked for conflicts. Filters for reducing common types of false alerts were implemented. The new detection methods were tested in three different ways. First, a simple flightpath command language was developed t o generate precisely controlled encounters for the purpose of testing the detection software. Second, written reports and tracking data were obtained for actual operational errors that occurred in the field, and these were "replayed" to test the new detection algorithms. Finally, the detection methods were used to shadow live traffic, and performance was analysed, particularly with regard to the false-alert rate. The results indicate that the new detection methods can provide timely warnings of imminent conflicts more consistently than Conflict Alert.

  20. Improved Conflict Detection for Reducing Operational Errors in Air Traffic Control

    NASA Technical Reports Server (NTRS)

    Paielli, Russell A.; Erzberger, Hainz

    2003-01-01

    An operational error is an incident in which an air traffic controller allows the separation between two aircraft to fall below the minimum separation standard. The rates of such errors in the US have increased significantly over the past few years. This paper proposes new detection methods that can help correct this trend by improving on the performance of Conflict Alert, the existing software in the Host Computer System that is intended to detect and warn controllers of imminent conflicts. In addition to the usual trajectory based on the flight plan, a "dead-reckoning" trajectory (current velocity projection) is also generated for each aircraft and checked for conflicts. Filters for reducing common types of false alerts were implemented. The new detection methods were tested in three different ways. First, a simple flightpath command language was developed t o generate precisely controlled encounters for the purpose of testing the detection software. Second, written reports and tracking data were obtained for actual operational errors that occurred in the field, and these were "replayed" to test the new detection algorithms. Finally, the detection methods were used to shadow live traffic, and performance was analysed, particularly with regard to the false-alert rate. The results indicate that the new detection methods can provide timely warnings of imminent conflicts more consistently than Conflict Alert.

  1. Effect of the Error of Measurement of Current Harmonics on the Accuracy of Determination of Magnetic Characteristics

    NASA Astrophysics Data System (ADS)

    Gorbatenko, N. I.; Lankin, A. M.; Lankin, M. V.

    2017-01-01

    The effect of the error of measurement of the form of current harmonics on the accuracy of determination of weber-ampere characteristics of electrical devices is studied. The developed method for determining weber-ampere characteristics makes it possible to plot them for ac electrical devices in terms of the amplitude and frequency of the input voltage and of the measured current waveform. The effect of the error of measurement of the waveform on the weber-ampere characteristic obtained is studied.

  2. IM Direct Torque Control with no flux distortion and no static torque error.

    PubMed

    Lokriti, Abdesslam; Salhi, Issam; Doubabi, Said

    2015-11-01

    The purpose of this paper is to improve DTC control strategy performances. In fact, we propose controlling both stator flux components (real and imaginary) through two hysteresis controllers. Thus, a new switching table which is independent from sector determination, and does not introduce zero voltage vectors is established; with much reduced size when compared to Takahashi's one. The proposed strategy has allowed cutting off with flux and current harmonics related to distortion caused by sector exchanges. Also, we provide theoretical evidence about the existence of static torque error in classical DTC, and propose a simple PI-type controller to cancel it. The proposed strategy is validated by simulation and practically on a DSPace 1104 board, for a 1.5 (kW) induction motor and various torque references.

  3. A cascaded coding scheme for error control and its performance analysis

    NASA Technical Reports Server (NTRS)

    Kasami, Tadao; Fujiwara, Toru; Takata, Toyoo; Lin, Shu

    1988-01-01

    A coding scheme for error control in data communication systems is investigated. The scheme is obtained by cascading two error-correcting codes, called the inner and outer codes. Its error performance is analyzed for a binary symmetric channel with bit-error rate epsilon less than 1/2. It is shown that, if the inner and outer codes are chosen properly, high reliability can be attained even for a high-channel bit-error rate. Specific examples with inner codes ranging from high rates and Reed-Solomon codes as outer codes are considered, and their error probabilities evaluated. They all provide high reliability even for high bit-error rates, say 0.1-0.01. Several example schemes are being considered for satellite and spacecraft downlink error control.

  4. A cascaded coding scheme for error control and its performance analysis

    NASA Technical Reports Server (NTRS)

    Lin, Shu; Kasami, Tadao; Fujiwara, Tohru; Takata, Toyoo

    1986-01-01

    A coding scheme is investigated for error control in data communication systems. The scheme is obtained by cascading two error correcting codes, called the inner and outer codes. The error performance of the scheme is analyzed for a binary symmetric channel with bit error rate epsilon <1/2. It is shown that if the inner and outer codes are chosen properly, extremely high reliability can be attained even for a high channel bit error rate. Various specific example schemes with inner codes ranging form high rates to very low rates and Reed-Solomon codes as inner codes are considered, and their error probabilities are evaluated. They all provide extremely high reliability even for very high bit error rates. Several example schemes are being considered by NASA for satellite and spacecraft down link error control.

  5. Post-error action control is neurobehaviorally modulated under conditions of constant speeded response

    PubMed Central

    Soshi, Takahiro; Ando, Kumiko; Noda, Takamasa; Nakazawa, Kanako; Tsumura, Hideki; Okada, Takayuki

    2015-01-01

    Post-error slowing (PES) is an error recovery strategy that contributes to action control, and occurs after errors in order to prevent future behavioral flaws. Error recovery often malfunctions in clinical populations, but the relationship between behavioral traits and recovery from error is unclear in healthy populations. The present study investigated the relationship between impulsivity and error recovery by simulating a speeded response situation using a Go/No-go paradigm that forced the participants to constantly make accelerated responses prior to stimuli disappearance (stimulus duration: 250 ms). Neural correlates of post-error processing were examined using event-related potentials (ERPs). Impulsivity traits were measured with self-report questionnaires (BIS-11, BIS/BAS). Behavioral results demonstrated that the commission error for No-go trials was 15%, but PES did not take place immediately. Delayed PES was negatively correlated with error rates and impulsivity traits, showing that response slowing was associated with reduced error rates and changed with impulsivity. Response-locked error ERPs were clearly observed for the error trials. Contrary to previous studies, error ERPs were not significantly related to PES. Stimulus-locked N2 was negatively correlated with PES and positively correlated with impulsivity traits at the second post-error Go trial: larger N2 activity was associated with greater PES and less impulsivity. In summary, under constant speeded conditions, error monitoring was dissociated from post-error action control, and PES did not occur quickly. Furthermore, PES and its neural correlate (N2) were modulated by impulsivity traits. These findings suggest that there may be clinical and practical efficacy of maintaining cognitive control of actions during error recovery under common daily environments that frequently evoke impulsive behaviors. PMID:25674058

  6. Error control techniques for satellite and space communications

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.

    1990-01-01

    An expurgated upper bound on the event error probability of trellis coded modulation is presented. This bound is used to derive a lower bound on the minimum achievable free Euclidean distance d sub (free) of trellis codes. It is shown that the dominant parameters for both bounds, the expurgated error exponent and the asymptotic d sub (free) growth rate, respectively, can be obtained from the cutoff-rate R sub O of the transmission channel by a simple geometric construction, making R sub O the central parameter for finding good trellis codes. Several constellations are optimized with respect to the bounds.

  7. Error control techniques for satellite and space communications

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.

    1994-01-01

    The unequal error protection capabilities of convolutional and trellis codes are studied. In certain environments, a discrepancy in the amount of error protection placed on different information bits is desirable. Examples of environments which have data of varying importance are a number of speech coding algorithms, packet switched networks, multi-user systems, embedded coding systems, and high definition television. Encoders which provide more than one level of error protection to information bits are called unequal error protection (UEP) codes. In this work, the effective free distance vector, d, is defined as an alternative to the free distance as a primary performance parameter for UEP convolutional and trellis encoders. For a given (n, k), convolutional encoder, G, the effective free distance vector is defined as the k-dimensional vector d = (d(sub 0), d(sub 1), ..., d(sub k-1)), where d(sub j), the j(exp th) effective free distance, is the lowest Hamming weight among all code sequences that are generated by input sequences with at least one '1' in the j(exp th) position. It is shown that, although the free distance for a code is unique to the code and independent of the encoder realization, the effective distance vector is dependent on the encoder realization.

  8. IPTV multicast with peer-assisted lossy error control

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Zhu, Xiaoqing; Begen, Ali C.; Girod, Bernd

    2010-07-01

    Emerging IPTV technology uses source-specific IP multicast to deliver television programs to end-users. To provide reliable IPTV services over the error-prone DSL access networks, a combination of multicast forward error correction (FEC) and unicast retransmissions is employed to mitigate the impulse noises in DSL links. In existing systems, the retransmission function is provided by the Retransmission Servers sitting at the edge of the core network. In this work, we propose an alternative distributed solution where the burden of packet loss repair is partially shifted to the peer IP set-top boxes. Through Peer-Assisted Repair (PAR) protocol, we demonstrate how the packet repairs can be delivered in a timely, reliable and decentralized manner using the combination of server-peer coordination and redundancy of repairs. We also show that this distributed protocol can be seamlessly integrated with an application-layer source-aware error protection mechanism called forward and retransmitted Systematic Lossy Error Protection (SLEP/SLEPr). Simulations show that this joint PARSLEP/ SLEPr framework not only effectively mitigates the bottleneck experienced by the Retransmission Servers, thus greatly enhancing the scalability of the system, but also efficiently improves the resistance to the impulse noise.

  9. Context specificity of post-error and post-conflict cognitive control adjustments.

    PubMed

    Forster, Sarah E; Cho, Raymond Y

    2014-01-01

    There has been accumulating evidence that cognitive control can be adaptively regulated by monitoring for processing conflict as an index of online control demands. However, it is not yet known whether top-down control mechanisms respond to processing conflict in a manner specific to the operative task context or confer a more generalized benefit. While previous studies have examined the taskset-specificity of conflict adaptation effects, yielding inconsistent results, control-related performance adjustments following errors have been largely overlooked. This gap in the literature underscores recent debate as to whether post-error performance represents a strategic, control-mediated mechanism or a nonstrategic consequence of attentional orienting. In the present study, evidence of generalized control following both high conflict correct trials and errors was explored in a task-switching paradigm. Conflict adaptation effects were not found to generalize across tasksets, despite a shared response set. In contrast, post-error slowing effects were found to extend to the inactive taskset and were predictive of enhanced post-error accuracy. In addition, post-error performance adjustments were found to persist for several trials and across multiple task switches, a finding inconsistent with attentional orienting accounts of post-error slowing. These findings indicate that error-related control adjustments confer a generalized performance benefit and suggest dissociable mechanisms of post-conflict and post-error control.

  10. Position control of redundant manipulators using an adaptive error-based control scheme

    NASA Technical Reports Server (NTRS)

    Nguyen, Charles C.; Zhou, Zhen-Lei

    1990-01-01

    A Cartesian-space control scheme is developed to control the motion of kinematically redundant manipulators with 7 degrees of freedom (DOF). The control scheme consists mainly of proportional derivative (PD) controllers whose gains are adjusted by an adaptation law driven by the errors between the desired and actual trajectories. The adaptation law is derived using the concept of model reference adaptive control (MRAC) and Lyapunov direct method under the assumption that the manipulator performs non-compliant and slowly-varying motions. The developed control scheme is computationally efficient because its implementation does not require the computation of the manipulator dynamics. Computer simulation performed to evaluate the control scheme performance is presented and discussed.

  11. Error analysis in the measurement of average power with application to switching controllers

    NASA Technical Reports Server (NTRS)

    Maisel, J. E.

    1980-01-01

    Power measurement errors due to the bandwidth of a power meter and the sampling of the input voltage and current of a power meter were investigated assuming sinusoidal excitation and periodic signals generated by a model of a simple chopper system. Errors incurred in measuring power using a microcomputer with limited data storage were also considered. The behavior of the power measurement error due to the frequency responses of first order transfer functions between the input sinusoidal voltage, input sinusoidal current, and the signal multiplier was studied. Results indicate that this power measurement error can be minimized if the frequency responses of the first order transfer functions are identical. The power error analysis was extended to include the power measurement error for a model of a simple chopper system with a power source and an ideal shunt motor acting as an electrical load for the chopper. The behavior of the power measurement error was determined as a function of the chopper's duty cycle and back EMF of the shunt motor. Results indicate that the error is large when the duty cycle or back EMF is small. Theoretical and experimental results indicate that the power measurement error due to sampling of sinusoidal voltages and currents becomes excessively large when the number of observation periods approaches one-half the size of the microcomputer data memory allocated to the storage of either the input sinusoidal voltage or current.

  12. Improving the Dynamic Response during Field Weakening Control of IPMSM Drive System using Adaptive Hysteresis Current Control Technique

    NASA Astrophysics Data System (ADS)

    Naik, Amiya; Panda, Anup Kumar; Kar, Sanjeeb Kumar

    2016-06-01

    This paper presents the control of IPMSM drive in flux weakening region, for high speed applications. An adaptive hysteresis band current controller has been designed and implemented in this work to overcome the drawbacks which are present in case of conventional hysteresis band current controllers such as: high torque ripple, more current error, large variation in switching frequency etc. The proposed current controller is a hysteresis controller in which the hysteresis band is programmed as a function of variation of motor speed and load current. Any variation in those parameters causes an appropriate change in the band which in turns reduces the torque ripple as well as current error of the machine. The proposed scheme is modeled and tested in the MATLAB-Simulink environment for the effectiveness of the study. Further, the result is validated experimentally by using TMS320F2812 digital signal processor.

  13. Optimization design of an adaptive CFRC reflector for high order wave-front error control

    NASA Astrophysics Data System (ADS)

    Lan, Lan; Fang, Houfei; Wu, Ke; Jiang, Shuidong; Zhou, Yang

    2017-04-01

    The trend in future space high precision reflectors is going towards large aperture, lightweight and actively controlled deformable antennas. An adaptive shape control system for a Carbon Fiber Reinforced Composite (CFRC) reflector is conducted by Piezoelectric Ceramic Transducer (PZT) actuators. This adaptive shape control system has been shown to effectively mitigate common low order wave-front error, but it is inevitably plagued by high order wave-front error control. In order to improve the controllability of the adaptive CFRC reflector control system for high order wave-front error, the design of adaptive CFRC reflector requires optimizing further. According to numerical and experimental results, the print-through error induced by manufacturing and PZT actuators actuation is a type of predominant high order wave-front error. This paper describes a design which some secondary rib elements are embedded within the triangular cells of the primary ribs. These small secondary ribs are designed to support the reflector surface's weak region. Controllability of this new adaptive CFRC reflector control system with small secondary ribs is evaluated by generalized Zernike functions. This new design scheme can reduce high order residual error and suppress the high order wave-front error such as print-through error. Finally, design parameters of the adaptive CFRC reflector control system with small secondary ribs, such as primary rib height, secondary rib height, cut-out height of primary rib, are optimized.

  14. An adaptive error control system using hybrid ARQ schemes

    NASA Astrophysics Data System (ADS)

    Kousa, Maan A.; Rahman, Mushfiqur

    1991-07-01

    A simple and efficient system utilizing the class of Hamming codes in a cascaded manner is proposed to provide high throughput over a wide range of channel bit-error probability. Comparisons with other adaptive schemes indicate that the proposed system is superior from the point of view of throughput, while still providing the same order of reliability as an ARQ (automatic repeat request) system. The main feature of this system is that the receiver uses the same decoder for decoding the received information after each transmission while the error-correcting capability of the code increases. As a result, the system is kept to the minimum complexity and the system performance is improved.

  15. When Errors Do Not Matter: Weakening Belief in Intentional Control Impairs Cognitive Reaction to Errors

    ERIC Educational Resources Information Center

    Rigoni, Davide; Wilquin, Helene; Brass, Marcel; Burle, Boris

    2013-01-01

    The belief that one can exert intentional control over behavior is deeply rooted in virtually all human beings. It has been shown that weakening such belief--e.g. by exposure to "anti-free will" messages--can lead people to display antisocial tendencies. We propose that this cursory and irresponsible behavior may be facilitated by a breakdown of…

  16. When Errors Do Not Matter: Weakening Belief in Intentional Control Impairs Cognitive Reaction to Errors

    ERIC Educational Resources Information Center

    Rigoni, Davide; Wilquin, Helene; Brass, Marcel; Burle, Boris

    2013-01-01

    The belief that one can exert intentional control over behavior is deeply rooted in virtually all human beings. It has been shown that weakening such belief--e.g. by exposure to "anti-free will" messages--can lead people to display antisocial tendencies. We propose that this cursory and irresponsible behavior may be facilitated by a breakdown of…

  17. Polarimeter calibration error gets far out of control

    NASA Astrophysics Data System (ADS)

    Chipman, Russell A.

    2015-09-01

    This is a sad story about a polarization calibration error gone amuck. A simple laboratory mistake was mistaken for a new phenomena. Aggressive management did their job and sold the flawed idea very effectively and substantial funding followed. Questions were raised and a Government lab tried but couldn't to recreate the breakthrough. The results were unpleasant and the field of infrared polarimetry developed a bad reputation for several years.

  18. An error-resistant linguistic protocol for air traffic control

    NASA Technical Reports Server (NTRS)

    Cushing, Steven

    1989-01-01

    The research results described here are intended to enhance the effectiveness of the DATALINK interface that is scheduled by the Federal Aviation Administration (FAA) to be deployed during the 1990's to improve the safety of various aspects of aviation. While voice has a natural appeal as the preferred means of communication both among humans themselves and between humans and machines as the form of communication that people find most convenient, the complexity and flexibility of natural language are problematic, because of the confusions and misunderstandings that can arise as a result of ambiguity, unclear reference, intonation peculiarities, implicit inference, and presupposition. The DATALINK interface will avoid many of these problems by replacing voice with vision and speech with written instructions. This report describes results achieved to date on an on-going research effort to refine the protocol of the DATALINK system so as to avoid many of the linguistic problems that still remain in the visual mode. In particular, a working prototype DATALINK simulator system has been developed consisting of an unambiguous, context-free grammar and parser, based on the current air-traffic-control language and incorporated into a visual display involving simulated touch-screen buttons and three levels of menu screens. The system is written in the C programming language and runs on the Macintosh II computer. After reviewing work already done on the project, new tasks for further development are described.

  19. Beam current controller for laser ion source

    DOEpatents

    Okamura, Masahiro

    2014-10-28

    The present invention relates to the design and use of an ion source with a rapid beam current controller for experimental and medicinal purposes. More particularly, the present invention relates to the design and use of a laser ion source with a magnetic field applied to confine a plasma flux caused by laser ablation.

  20. Performance analysis of a hybrid ARQ error control scheme for near earth satellite communications

    NASA Technical Reports Server (NTRS)

    Lin, Shu

    1987-01-01

    A robust error control coding scheme is presented. The scheme is a cascaded forward error correction (FEC) scheme supported by parity retransmissions for further error correction in the erroneous data words. The error performance and throughput efficiency of the scheme are analyzed. Two specific schemes are proposed for NASA near earth satellite communications. It is shown that both schemes provide high reliability and throughput efficiency even for high channel bit error rates in the range of .002. The schemes are suitable for high data rate file transfer.

  1. Current control of light by nonreciprocal magnetoplasmonics

    NASA Astrophysics Data System (ADS)

    Gong, Yongkang; Li, Kang; Carver, Sara; Martinez, Juan Jose; Huang, Jungang; Thueux, Yoann; Avlonitis, Nick; Copner, Nigel

    2015-05-01

    The ability to actively control light has long been a major scientific and technological goal. We proposed a scheme that allows for active control of light by utilizing the nonreciprocal magnetoplasmonic effect. As a proof of concept, we applied current signal through an ultrathin metallic film in a magneto-plasmonic multilayer and found that dynamic photonic nonreciprocity appears in magnetic-optical material layer due to the magnetic field being induced from current signal and modulates surface plasmon polaritons trapped in the metal surface and the light reflected. The proposed concept provides a possible way for the active control of light and could find potential applications such as ultrafast optoelectronic signal processing for plasmonic nanocircuit technology and ultrafast/large-aperture free-space electro-optic modulation platform for wireless laser communication technology.

  2. Current control of light by nonreciprocal magnetoplasmonics

    SciTech Connect

    Gong, Yongkang Li, Kang; Carver, Sara; Martinez, Juan Jose; Huang, Jungang; Copner, Nigel; Thueux, Yoann; Avlonitis, Nick

    2015-05-11

    The ability to actively control light has long been a major scientific and technological goal. We proposed a scheme that allows for active control of light by utilizing the nonreciprocal magnetoplasmonic effect. As a proof of concept, we applied current signal through an ultrathin metallic film in a magneto-plasmonic multilayer and found that dynamic photonic nonreciprocity appears in magnetic-optical material layer due to the magnetic field being induced from current signal and modulates surface plasmon polaritons trapped in the metal surface and the light reflected. The proposed concept provides a possible way for the active control of light and could find potential applications such as ultrafast optoelectronic signal processing for plasmonic nanocircuit technology and ultrafast/large-aperture free-space electro-optic modulation platform for wireless laser communication technology.

  3. Solar Cell Short Circuit Current Errors and Uncertainties During High Altitude Calibrations

    NASA Technical Reports Server (NTRS)

    Snyder, David D.

    2012-01-01

    High altitude balloon based facilities can make solar cell calibration measurements above 99.5% of the atmosphere to use for adjusting laboratory solar simulators. While close to on-orbit illumination, the small attenuation to the spectra may result in under measurements of solar cell parameters. Variations of stratospheric weather, may produce flight-to-flight measurement variations. To support the NSCAP effort, this work quantifies some of the effects on solar cell short circuit current (Isc) measurements on triple junction sub-cells. This work looks at several types of high altitude methods, direct high altitude meas urements near 120 kft, and lower stratospheric Langley plots from aircraft. It also looks at Langley extrapolation from altitudes above most of the ozone, for potential small balloon payloads. A convolution of the sub-cell spectral response with the standard solar spectrum modified by several absorption processes is used to determine the relative change from AMO, lscllsc(AMO). Rayleigh scattering, molecular scatterin g from uniformly mixed gases, Ozone, and water vapor, are included in this analysis. A range of atmosph eric pressures are examined, from 0. 05 to 0.25 Atm to cover the range of atmospheric altitudes where solar cell calibrations a reperformed. Generally these errors and uncertainties are less than 0.2%

  4. Study of Kink Modes and Error Fields using Rotation Control with a Biased Probe

    NASA Astrophysics Data System (ADS)

    Stoafer, Chris C.; Levesque, J. P.; Peng, Q.; Mauel, M. E.; Navratil, G. A.

    2015-11-01

    A bias probe has been installed in the High Beta Tokamak - Extended Pulse (HBT-EP) for studying MHD mode rotation and stability. When the probe is inserted into the edge of the plasma and a voltage applied, the rotation of long-wavelength kink instabilities is strongly modified. A large poloidal plasma flow results, measured with a bi-directional Mach probe, and changes in plasma flow correlate to changes in edge kink mode rotation. An active controller is used to adjust the probe voltage in real time for controlling both the plasma flow and mode rotation. Bias probe voltages are generated through an active GPU-based digital feedback system. Mode rotation control is desirable and allows for MHD stability studies under conditions of varying mode rotation rates. At large positive biases, the probe current induces a torque that opposes the natural direction of mode rotation. We are able to apply sufficiently large torque to induce a transition to a fast rotation state (both mode and plasma rotation). The bias required to induce the transition is shown to depend on an applied error field, establishing a technique to determine the natural error field on HBT-EP. Supported by U.S. DOE Grant DE-FG02-86ER53222.

  5. Current limiting remote power control module

    NASA Technical Reports Server (NTRS)

    Hopkins, Douglas C.

    1990-01-01

    The power source for the Space Station Freedom will be fully utilized nearly all of the time. As such, any loads on the system will need to operate within expected limits. Should any load draw an inordinate amount of power, the bus voltage for the system may sag and disrupt the operation of other loads. To protect the bus and loads some type of power interface between the bus and each load must be provided. This interface is most crucial when load faults occur. A possible system configuration is presented. The proposed interface is the Current Limiting Remote Power Controller (CL-RPC). Such an interface should provide the following power functions: limit overloading and resulting undervoltage; prevent catastrophic failure and still provide for redundancy management within the load; minimize cable heating; and provide accurate current measurement. A functional block diagram of the power processing stage of a CL-RPC is included. There are four functions that drive the circuit design: rate control of current; current sensing; the variable conductance switch (VCS) technology; and the algorithm used for current limiting. Each function is discussed separately.

  6. Error Control Coding Techniques for Space and Satellite Communications

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.; Cabral, Hermano A.; He, Jiali

    1997-01-01

    Bootstrap Hybrid Decoding (BHD) (Jelinek and Cocke, 1971) is a coding/decoding scheme that adds extra redundancy to a set of convolutionally encoded codewords and uses this redundancy to provide reliability information to a sequential decoder. Theoretical results indicate that bit error probability performance (BER) of BHD is close to that of Turbo-codes, without some of their drawbacks. In this report we study the use of the Multiple Stack Algorithm (MSA) (Chevillat and Costello, Jr., 1977) as the underlying sequential decoding algorithm in BHD, which makes possible an iterative version of BHD.

  7. Current Profile Control in DIII-D

    NASA Astrophysics Data System (ADS)

    Schuster, E. M.; Barton, J. E.; Boyer, M. D.; Wehner, W. P.; Ferron, J. R.; Humphreys, D. A.; Hyatt, A. W.; Jackson, G. L.; Luce, T. C.; Walker, M. L.

    2014-10-01

    Experimental results successfully demonstrate the potential of physics-model-based control for systematic attainment of desired q profiles, with the subsequent benefit of enabling exploration and reproducibility. The control scheme is constructed by embedding a nonlinear, control-oriented, physics-based model of the plasma dynamics into the control design process. This modeling approach combines first-principles laws with empirical correlations obtained from physical observations, which leads to PDE models capturing the high-dimensionality and nonlinearity of the plasma response. Model-based control design includes not only the synthesis of feedback controllers for robust regulation or tracking, but also the determination of optimal feedforward actuator trajectories for a systematic approach to scenario planning. Feedforward+feedback (closed loop) control experiments in DIII-D consistently demonstrate improved current-profile control performance relative to feedforward (open loop) control alone. Supported by the US Department of Energy under DE-SC0001334, DE-SC0010661 and DE-FC02-04ER54698.

  8. Simultaneous control of error rates in fMRI data analysis.

    PubMed

    Kang, Hakmook; Blume, Jeffrey; Ombao, Hernando; Badre, David

    2015-12-01

    The key idea of statistical hypothesis testing is to fix, and thereby control, the Type I error (false positive) rate across samples of any size. Multiple comparisons inflate the global (family-wise) Type I error rate and the traditional solution to maintaining control of the error rate is to increase the local (comparison-wise) Type II error (false negative) rates. However, in the analysis of human brain imaging data, the number of comparisons is so large that this solution breaks down: the local Type II error rate ends up being so large that scientifically meaningful analysis is precluded. Here we propose a novel solution to this problem: allow the Type I error rate to converge to zero along with the Type II error rate. It works because when the Type I error rate per comparison is very small, the accumulation (or global) Type I error rate is also small. This solution is achieved by employing the likelihood paradigm, which uses likelihood ratios to measure the strength of evidence on a voxel-by-voxel basis. In this paper, we provide theoretical and empirical justification for a likelihood approach to the analysis of human brain imaging data. In addition, we present extensive simulations that show the likelihood approach is viable, leading to "cleaner"-looking brain maps and operational superiority (lower average error rate). Finally, we include a case study on cognitive control related activation in the prefrontal cortex of the human brain.

  9. VOC Control: Current practices and future trends

    SciTech Connect

    Moretti, E.C.; Mukhopadhyay, N. )

    1993-07-01

    One of the most formidable challenges posed by the Clean Air Act Amendments of 1990 (CAAA) is the search for efficient and economical control strategies for volatile organic compounds (VOCs). VOCs are precursors to ground-level ozone, a major component in the formation of smog. Under the CAAA, thousands of currently unregulated sources will be required to reduce or eliminate VOC emissions. In addition, sources that are currently regulated may seek to evaluate alternative VOC control strategies to meet stricter regulatory requirements such as the maximum achievable control technology (MACT) requirements in Title III of the CAAA. Because of the increasing attention being given to VOC control, the American Institute of Chemical Engineers' (AIChE) Center for Waste Reduction Technologies (CWRT) initiated a study of VOC control technologies and regulatory initiatives. A key objective of the project was to identify and describe existing VOC control technologies and air regulations, as well as emerging technologies and forthcoming regulations. That work is the basis for this article.

  10. Error analysis in the measurement of average power with application to switching controllers

    NASA Technical Reports Server (NTRS)

    Maisel, J. E.

    1979-01-01

    The behavior of the power measurement error due to the frequency responses of first order transfer functions between the input sinusoidal voltage, input sinusoidal current and the signal multiplier was studied. It was concluded that this measurement error can be minimized if the frequency responses of the first order transfer functions are identical.

  11. Digitally Controllable Current Amplifier and Current Conveyors in Practical Application of Controllable Frequency Filter

    NASA Astrophysics Data System (ADS)

    Polak, Josef; Jerabek, Jan; Langhammer, Lukas; Sotner, Roman; Dvorak, Jan; Panek, David

    2016-07-01

    This paper presents the simulations results in comparison with the measured results of the practical realization of the multifunctional second order frequency filter with a Digitally Adjustable Current Amplifier (DACA) and two Dual-Output Controllable Current Conveyors (CCCII +/-). This filter is designed for use in current mode. The filter was designed of the single input multiple outputs (SIMO) type, therefore it has only one input and three outputs with individual filtering functions. DACA element used in a newly proposed circuit is present in form of an integrated chip and the current conveyors are implemented using the Universal Current Conveyor (UCC) chip with designation UCC-N1B. Proposed frequency filter enables independent control of the pole frequency using parameters of two current conveyors and also independent control of the quality factor by change of a current gain of DACA.

  12. Error control techniques for satellite and space communications

    NASA Technical Reports Server (NTRS)

    Costello, D. J., Jr.

    1986-01-01

    High rate concatenated coding systems with trellis inner codes and Reed-Solomon (RS) outer codes for application in satellite communication systems are considered. Two types of inner codes are studied: high rate punctured binary convolutional codes which result in overall effective information rates between 1/2 and 1 bit per channel use; and bandwidth efficient signal space trellis codes which can achieve overall effective information rates greater than 1 bit per channel use. Channel capacity calculations with and without side information performed for the concatenated coding system. Concatenated coding schemes are investigated. In Scheme 1, the inner code is decoded with the Viterbi algorithm and the outer RS code performs error-correction only (decoding without side information). In scheme 2, the inner code is decoded with a modified Viterbi algorithm which produces reliability information along with the decoded output. In this algorithm, path metrics are used to estimate the entire information sequence, while branch metrics are used to provide the reliability information on the decoded sequence. This information is used to erase unreliable bits in the decoded output. An errors-and-erasures RS decoder is then used for the outer code. These two schemes are proposed for use on NASA satellite channels. Results indicate that high system reliability can be achieved with little or no bandwidth expansion.

  13. Error Control Coding Techniques for Space and Satellite Communications

    NASA Technical Reports Server (NTRS)

    Lin, Shu

    2000-01-01

    This paper presents a concatenated turbo coding system in which a Reed-Solomom outer code is concatenated with a binary turbo inner code. In the proposed system, the outer code decoder and the inner turbo code decoder interact to achieve both good bit error and frame error performances. The outer code decoder helps the inner turbo code decoder to terminate its decoding iteration while the inner turbo code decoder provides soft-output information to the outer code decoder to carry out a reliability-based soft-decision decoding. In the case that the outer code decoding fails, the outer code decoder instructs the inner code decoder to continue its decoding iterations until the outer code decoding is successful or a preset maximum number of decoding iterations is reached. This interaction between outer and inner code decoders reduces decoding delay. Also presented in the paper are an effective criterion for stopping the iteration process of the inner code decoder and a new reliability-based decoding algorithm for nonbinary codes.

  14. Error control techniques for satellite and space communications

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.

    1995-01-01

    This report focuses on the results obtained during the PI's recent sabbatical leave at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, from January 1, 1995 through June 30, 1995. Two projects investigated various properties of TURBO codes, a new form of concatenated coding that achieves near channel capacity performance at moderate bit error rates. The performance of TURBO codes is explained in terms of the code's distance spectrum. These results explain both the near capacity performance of the TURBO codes and the observed 'error floor' for moderate and high signal-to-noise ratios (SNR's). A semester project, entitled 'The Realization of the Turbo-Coding System,' involved a thorough simulation study of the performance of TURBO codes and verified the results claimed by previous authors. A copy of the final report for this project is included as Appendix A. A diploma project, entitled 'On the Free Distance of Turbo Codes and Related Product Codes,' includes an analysis of TURBO codes and an explanation for their remarkable performance. A copy of the final report for this project is included as Appendix B.

  15. A current-controlled, dynamic magnonic crystal

    NASA Astrophysics Data System (ADS)

    Chumak, A. V.; Neumann, T.; Serga, A. A.; Hillebrands, B.; Kostylev, M. P.

    2009-10-01

    We present a current-controlled magnonic crystal consisting of a ferrite film in which spin waves propagate and a set of parallel, periodically spaced, current conducting stripes placed close to the film surface. The current flow causes a sine-like variation of the film's internal magnetic field, which can be modulated by changing the amount of current. Transmission measurements reveal a single, pronounced rejection band. With increasing current strength the rejection band depth and its width increase strongly. Moreover, it is possible to switch the artificial, periodic structure on and off, so that the waveguide makes a transition from full rejection to full transmission within less than 50 ns. Numerical simulations confirm the experimental results and show that the spin-wave propagation in the crystal can be effectively described as a scattering process in the first Born approximation. Three ways to increase the reflection efficiency of the magnonic crystal are identified: an increased number of periods, an increased lattice constant and a decreased spacing between the current carrying structure and the waveguide.

  16. Optimal control design that accounts for model mismatch errors

    SciTech Connect

    Kim, T.J.; Hull, D.G.

    1995-02-01

    A new technique is presented in this paper that reduces the complexity of state differential equations while accounting for modeling assumptions. The mismatch controls are defined as the differences between the model equations and the true state equations. The performance index of the optimal control problem is formulated with a set of tuning parameters that are user-selected to tune the control solution in order to achieve the best results. Computer simulations demonstrate that the tuned control law outperforms the untuned controller and produces results that are comparable to a numerically-determined, piecewise-linear optimal controller.

  17. Stray current interference control for HVDC earth currents

    SciTech Connect

    Fitzgerald, J.H. III

    1995-06-01

    High-voltage direct current (HVDC) transmission lines exist around the world, with several in the US. When one conductor must be taken out of operation (in case of emergency), the earth may be used as an alternate conductor. The earth current may be accumulated on and discharged from underground metallic structures that cross the voltage gradient created by the current. Test results on two lines showed that stray current interference is not a major problem if mitigated properly.

  18. Two-stage feedforward tracking control system with error-based disturbance observer for optical discs

    NASA Astrophysics Data System (ADS)

    Sakimura, Naohide; Ohashi, Takahiro; Ohishi, Kiyoshi; Miyazaki, Toshimasa

    2014-09-01

    Recently, the scaling up of the storage capacity and data transfer rate of digital storage media has been required. However, increasing in the storage capacity and transfer rate makes optical head control more difficult. Thus, a tracking control system for optical discs must exhibit a high degree of precision control. Consequently, a new two-stage feedforward control (TSFFC) system for high-precision control is proposed in this paper. The proposed system is constructed using two zero phase error tracking (ZPET) control systems based on error prediction and an error-based disturbance observer (EDOB) that uses a notch filter to suppress non periodic disturbances. The proposed control system is designed for DDU-1000 for digital versatile discs (DVDs). The experimental results demonstrate that the proposed system effectively suppresses tracking errors.

  19. ERP evidence of adaptive changes in error processing and attentional control during rhythm synchronization learning.

    PubMed

    Padrão, Gonçalo; Penhune, Virginia; de Diego-Balaguer, Ruth; Marco-Pallares, Josep; Rodriguez-Fornells, Antoni

    2014-10-15

    The ability to detect and use information from errors is essential during the acquisition of new skills. There is now a wealth of evidence about the brain mechanisms involved in error processing. However, the extent to which those mechanisms are engaged during the acquisition of new motor skills remains elusive. Here we examined rhythm synchronization learning across 12 blocks of practice in musically naïve individuals and tracked changes in ERP signals associated with error-monitoring and error-awareness across distinct learning stages. Synchronization performance improved with practice, and performance improvements were accompanied by dynamic changes in ERP components related to error-monitoring and error-awareness. Early in learning, when performance was poor and the internal representations of the rhythms were weaker we observed a larger error-related negativity (ERN) following errors compared to later learning. The larger ERN during early learning likely results from greater conflict between competing motor responses, leading to greater engagement of medial-frontal conflict monitoring processes and attentional control. Later in learning, when performance had improved, we observed a smaller ERN accompanied by an enhancement of a centroparietal positive component resembling the P3. This centroparietal positive component was predictive of participant's performance accuracy, suggesting a relation between error saliency, error awareness and the consolidation of internal templates of the practiced rhythms. Moreover, we showed that during rhythm learning errors led to larger auditory evoked responses related to attention orientation which were triggered automatically and which were independent of the learning stage. The present study provides crucial new information about how the electrophysiological signatures related to error-monitoring and error-awareness change during the acquisition of new skills, extending previous work on error processing and cognitive

  20. Error bounds of adaptive dynamic programming algorithms for solving undiscounted optimal control problems.

    PubMed

    Liu, Derong; Li, Hongliang; Wang, Ding

    2015-06-01

    In this paper, we establish error bounds of adaptive dynamic programming algorithms for solving undiscounted infinite-horizon optimal control problems of discrete-time deterministic nonlinear systems. We consider approximation errors in the update equations of both value function and control policy. We utilize a new assumption instead of the contraction assumption in discounted optimal control problems. We establish the error bounds for approximate value iteration based on a new error condition. Furthermore, we also establish the error bounds for approximate policy iteration and approximate optimistic policy iteration algorithms. It is shown that the iterative approximate value function can converge to a finite neighborhood of the optimal value function under some conditions. To implement the developed algorithms, critic and action neural networks are used to approximate the value function and control policy, respectively. Finally, a simulation example is given to demonstrate the effectiveness of the developed algorithms.

  1. Reed Solomon codes for error control in byte organized computer memory systems

    NASA Technical Reports Server (NTRS)

    Lin, S.; Costello, D. J., Jr.

    1984-01-01

    A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256K-bit DRAM's are organized in 32Kx8 bit-bytes. Byte oriented codes such as Reed Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. Some special decoding techniques for extended single-and-double-error-correcting RS codes which are capable of high speed operation are presented. These techniques are designed to find the error locations and the error values directly from the syndrome without having to use the iterative algorithm to find the error locator polynomial.

  2. Efficient ARQ schemes for error control of satellite channels

    NASA Astrophysics Data System (ADS)

    Fantacci, Romano

    1989-09-01

    In this paper, the performance of some efficient ARQ schemes which make use of repeated transmissions of the same data block and compound detection are analyzed. The repeated transmission of the same data block involves repeated transmission of each symbol of the data block. At the receiving end, compound detection formed of a soft detection jointly with a classical hard detection is performed by using all the received copies of the same symbol. The throughput efficiencies for the proposed ARQ schemes are analytically derived in closed form and optimized with respect to the number of copies to be transmitted for each data block. It will be shown that the optimized ARQ schemes proposed in this paper achieve better performance than classical ARQ schemes, in particular under high error rate conditions.

  3. Error control techniques for satellite and space communications

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.

    1992-01-01

    Worked performed during the reporting period is summarized. Construction of robustly good trellis codes for use with sequential decoding was developed. The robustly good trellis codes provide a much better trade off between free distance and distance profile. The unequal error protection capabilities of convolutional codes was studied. The problem of finding good large constraint length, low rate convolutional codes for deep space applications is investigated. A formula for computing the free distance of 1/n convolutional codes was discovered. Double memory (DM) codes, codes with two memory units per unit bit position, were studied; a search for optimal DM codes is being conducted. An algorithm for constructing convolutional codes from a given quasi-cyclic code was developed. Papers based on the above work are included in the appendix.

  4. Direct heuristic dynamic programming for nonlinear tracking control with filtered tracking error.

    PubMed

    Yang, Lei; Si, Jennie; Tsakalis, Konstantinos S; Rodriguez, Armando A

    2009-12-01

    This paper makes use of the direct heuristic dynamic programming design in a nonlinear tracking control setting with filtered tracking error. A Lyapunov stability approach is used for the stability analysis of the tracking system. It is shown that the closed-loop tracking error and the approximating neural network weight estimates retain the property of uniformly ultimate boundedness under the presence of neural network approximation error and bounded unknown disturbances under certain conditions.

  5. Deep space communications, weather effects, and error control

    NASA Technical Reports Server (NTRS)

    Posner, Edward C.

    1989-01-01

    Deep space telemetry is and will remain signal-to-noise limited and vulnerable to interference. A need exists to increase received signal power and decrease noise. This includes going to Ka-band in the mid-1990's to increase directivity. The effects of a wet atmosphere can increase the noise temperature by a factor of 5 or more, even at X-band, but the order of magnitude increase in average data rate obtainable at Ka-band relative to X-band makes the increased uncertainty a good trade. Lowbit error probabilities required by data compression are available both theoretically and practically with coding, at an infinitesimal power penalty rather than the 10 to 15 dB more power required to reduce error probabilities without coding. Advances are coming rapidly in coding, as with the new constraint-length 15 rate 1/4 convolutional code concatenated with the already existing Reed-Solomon code to be demonstrated on Galileo. In addition, high density spacecraft data storage will allow selective retransmissions, even from the edge of the Solar System, to overcome weather effects. In general, deep space communication was able to operate, and will continue to operate, closer to theoretical limits than any other form of communication. These include limits in antenna area and directivity, system noise temperature, coding efficiency, and everything else. The deep space communication links of the mid-90's and beyond will be compatible with new instruments and compression algorithms and represent a sensible investment in an overall end-to-end information system design.

  6. Error-preceding brain activity reflects (mal-)adaptive adjustments of cognitive control: a modeling study.

    PubMed

    Steinhauser, Marco; Eichele, Heike; Juvodden, Hilde T; Huster, Rene J; Ullsperger, Markus; Eichele, Tom

    2012-01-01

    Errors in choice tasks are preceded by gradual changes in brain activity presumably related to fluctuations in cognitive control that promote the occurrence of errors. In the present paper, we use connectionist modeling to explore the hypothesis that these fluctuations reflect (mal-)adaptive adjustments of cognitive control. We considered ERP data from a study in which the probability of conflict in an Eriksen-flanker task was manipulated in sub-blocks of trials. Errors in these data were preceded by a gradual decline of N2 amplitude. After fitting a connectionist model of conflict adaptation to the data, we analyzed simulated N2 amplitude, simulated response times (RTs), and stimulus history preceding errors in the model, and found that the model produced the same pattern as obtained in the empirical data. Moreover, this pattern is not found in alternative models in which cognitive control varies randomly or in an oscillating manner. Our simulations suggest that the decline of N2 amplitude preceding errors reflects an increasing adaptation of cognitive control to specific task demands, which leads to an error when these task demands change. Taken together, these results provide evidence that error-preceding brain activity can reflect adaptive adjustments rather than unsystematic fluctuations of cognitive control, and therefore, that these errors are actually a consequence of the adaptiveness of human cognition.

  7. Finite Time Control Design for Bilateral Teleoperation System With Position Synchronization Error Constrained.

    PubMed

    Yang, Yana; Hua, Changchun; Guan, Xinping

    2016-03-01

    Due to the cognitive limitations of the human operator and lack of complete information about the remote environment, the work performance of such teleoperation systems cannot be guaranteed in most cases. However, some practical tasks conducted by the teleoperation system require high performances, such as tele-surgery needs satisfactory high speed and more precision control results to guarantee patient' health status. To obtain some satisfactory performances, the error constrained control is employed by applying the barrier Lyapunov function (BLF). With the constrained synchronization errors, some high performances, such as, high convergence speed, small overshoot, and an arbitrarily predefined small residual constrained synchronization error can be achieved simultaneously. Nevertheless, like many classical control schemes only the asymptotic/exponential convergence, i.e., the synchronization errors converge to zero as time goes infinity can be achieved with the error constrained control. It is clear that finite time convergence is more desirable. To obtain a finite-time synchronization performance, the terminal sliding mode (TSM)-based finite time control method is developed for teleoperation system with position error constrained in this paper. First, a new nonsingular fast terminal sliding mode (NFTSM) surface with new transformed synchronization errors is proposed. Second, adaptive neural network system is applied for dealing with the system uncertainties and the external disturbances. Third, the BLF is applied to prove the stability and the nonviolation of the synchronization errors constraints. Finally, some comparisons are conducted in simulation and experiment results are also presented to show the effectiveness of the proposed method.

  8. Determining Current Insulin Pen Use Practices and Errors in the Inpatient Setting.

    PubMed

    Brown, Katelyn E; Hertig, John B

    2016-12-01

    The use of insulin pens in the inpatient setting has continued to be a controversial decision. Insulin pens provide several advantages, but given significant reports of medication errors, several organizations have issued alerts to caution users about safety concerns. A survey was conducted to assess the prevalence of insulin pen use and current utilization trends in the inpatient setting. The 31-question guided-logic survey was developed based on review of primary literature regarding insulin pen utilization and evaluated by a panel of medication safety experts from a variety of health care settings. The survey was sent electronically to subscribers of medication safety organizations. The survey was completed by 474 respondents. Approximately three fourths of respondents indicated insulin pens were on formulary at their institution (n = 332; 74%). Of those who have had insulin pens on formulary, 15% (n = 49) are no longer using them. The most common reasons for not utilizing pens were cost and safety concerns. Pens were reported to be stored in the pharmacy prior to administration (n = 230; 78%) and in a patient's bin (n = 202; 69%) afterward. More than half of respondents use two patient identifiers on the pen and label with a bar code. Approximately 30% reported that an insulin pen has been used on more than one patient at least once in their institution, while 6% were not sure. Insulin pens are widely being used in the inpatient setting. Various mitigation strategies are employed to reduce the risk of harm associated with insulin pen use. Health care professionals believe insulin pens are clinically useful and can be used safely in the inpatient setting. Many organizations and expert panels disseminate best practices in an effort to help ensure their safety. Further studies are needed to assess and validate the risk mitigation strategies identified through this research. Copyright 2016 The Joint Commission.

  9. Correcting image placement errors using registration control (RegC®) technology in the photomask periphery

    NASA Astrophysics Data System (ADS)

    Cohen, Avi; Lange, Falk; Ben-Zvi, Guy; Graitzer, Erez; Vladimir, Dmitriev

    2012-11-01

    The ITRS roadmap specifies wafer overlay control as one of the major tasks for the sub 40 nm nodes in addition to CD control and defect control. Wafer overlay is strongly dependent on mask image placement error (registration errors or Reg errors)1. The specifications for registration or mask placement accuracy are significantly tighter in some of the double patterning techniques (DPT). This puts a heavy challenge on mask manufacturers (mask shops) to comply with advanced node registration specifications. The conventional methods of feeding back the systematic registration error to the E-beam writer and re-writing the mask are becoming difficult, expensive and not sufficient for the advanced nodes especially for double pattering technologies. Six production masks were measured on a standard registration metrology tool and the registration errors were calculated and plotted. Specially developed algorithm along with the RegC Wizard (dedicated software) was used to compute a correction lateral strain field that would minimize the registration errors. This strain field was then implemented in the photomask bulk material using an ultra short pulse laser based system. Finally the post process registration error maps were measured and the resulting residual registration error field with and without scale and orthogonal errors removal was calculated. In this paper we present a robust process flow in the mask shop which leads up to 32% registration 3sigma improvement, bringing some out-of-spec masks into spec, utilizing the RegC® process in the photomask periphery while leaving the exposure field optically unaffected.

  10. Make no mistake—errors can be controlled*

    PubMed Central

    Hinckley, C

    2003-01-01

    

 Traditional quality control methods identify "variation" as the enemy. However, the control of variation by itself can never achieve the remarkably low non-conformance rates of world class quality leaders. Because the control of variation does not achieve the highest levels of quality, an inordinate focus on these techniques obscures key quality improvement opportunities and results in unnecessary pain and suffering for patients, and embarrassment, litigation, and loss of revenue for healthcare providers. Recent experience has shown that mistakes are the most common cause of problems in health care as well as in other industrial environments. Excessive product and process complexity contributes to both excessive variation and unnecessary mistakes. The best methods for controlling variation, mistakes, and complexity are each a form of mistake proofing. Using these mistake proofing techniques, virtually every mistake and non-conformance can be controlled at a fraction of the cost of traditional quality control methods. PMID:14532368

  11. Predictive current control of permanent magnet synchronous motor based on linear active disturbance rejection control

    NASA Astrophysics Data System (ADS)

    Li, Kunpeng

    2017-01-01

    The compatibility problem between rapidity and overshooting in the traditional predictive current control structure is inevitable and difficult to solve by reason of using PI controller. A novel predictive current control (PCC) algorithm for permanent magnet synchronous motor (PMSM) based on linear active disturbance rejection control (LADRC) is presented in this paper. In order to displace PI controller, the LADRC strategy which consisted of linear state error feedback (LSEF) control algorithm and linear extended state observer (LESO), is designed based on the mathematic model of PMSM. The purpose of LSEF is to make sure fast response to load mutation and system uncertainties, and LESO is designed to estimate the uncertain disturbances. The principal structures of the proposed system are speed outer loop based on LADRC and current inner loop based on predictive current control. Especially, the instruction value of qaxis current in inner loop is derived from the control quantity which is designed in speed outer loop. The simulation is carried out in Matlab/Simulink software, and the results illustrate that the dynamic and static performances of proposed system are satisfied. Moreover the robust against model parameters mismatch is enhanced obviously.

  12. Sliding mode output feedback control based on tracking error observer with disturbance estimator.

    PubMed

    Xiao, Lingfei; Zhu, Yue

    2014-07-01

    For a class of systems who suffers from disturbances, an original output feedback sliding mode control method is presented based on a novel tracking error observer with disturbance estimator. The mathematical models of the systems are not required to be with high accuracy, and the disturbances can be vanishing or nonvanishing, while the bounds of disturbances are unknown. By constructing a differential sliding surface and employing reaching law approach, a sliding mode controller is obtained. On the basis of an extended disturbance estimator, a creative tracking error observer is produced. By using the observation of tracking error and the estimation of disturbance, the sliding mode controller is implementable. It is proved that the disturbance estimation error and tracking observation error are bounded, the sliding surface is reachable and the closed-loop system is robustly stable. The simulations on a servomotor positioning system and a five-degree-of-freedom active magnetic bearings system verify the effect of the proposed method.

  13. The current approach to human error and blame in the NHS.

    PubMed

    Ottewill, Melanie

    There is a large body of research to suggest that serious errors are widespread throughout medicine. The traditional response to these adverse events has been to adopt a 'person approach' - blaming the individual seen as 'responsible'. The culture of medicine is highly complicit in this response. Such an approach results in enormous personal costs to the individuals concerned and does little to address the root causes of errors and thus prevent their recurrence. Other industries, such as aviation, where safety is a paramount concern and which have similar structures to the medical profession, have, over the past decade or so, adopted a 'systems' approach to error, recognizing that human error is ubiquitous and inevitable and that systems need to be developed with this in mind. This approach has been highly successful, but has necessitated, first and foremost, a cultural shift. It is in the best interests of patients, and medical professionals alike, that such a shift is embraced in the NHS.

  14. A three-component model of the control error in manual tracking of continuous random signals.

    PubMed

    Gerisch, Hans; Staude, Gerhard; Wolf, Werner; Bauch, Gerhard

    2013-10-01

    The performance of human operators acting within closed-loop control systems is investigated in a classic tracking task. The dependence of the control error (tracking error) on the parameters display gain, k(display), and input signal frequency bandwidth, f(g), which alter task difficulty and presumably the control delay, is studied with the aim of functionally specifying it via a model. The human operator as an element of a cascaded human-machine control system (e.g., car driving or piloting an airplane) codetermines the overall system performance. Control performance of humans in continuous tracking has been described in earlier studies. Using a handheld joystick, 10 participants tracked continuous random input signals. The parameters f(g) and k(display) were altered between experiments. Increased task difficulty promoted lengthened control delay and, consequently, increased control error.Tracking performance degraded profoundly with target deflection components above 1 Hz, confirming earlier reports. The control error is composed of a delay-induced component, a demand-based component, and a novel component: a human tracking limit. Accordingly, a new model that allows concepts of the observed control error to be split into these three components is suggested. To achieve optimal performance in control systems that include a human operator (e.g., vehicles, remote controlled rovers, crane control), (a) tasks should be kept as simple as possible to achieve shortest control delays, and (b) task components requiring higher-frequency (> 1 Hz) tracking actions should be avoided or automated by technical systems.

  15. The Accuracy of Webcams in 2D Motion Analysis: Sources of Error and Their Control

    ERIC Educational Resources Information Center

    Page, A.; Moreno, R.; Candelas, P.; Belmar, F.

    2008-01-01

    In this paper, we show the potential of webcams as precision measuring instruments in a physics laboratory. Various sources of error appearing in 2D coordinate measurements using low-cost commercial webcams are discussed, quantifying their impact on accuracy and precision, and simple procedures to control these sources of error are presented.…

  16. Using Mendelian inheritance errors as quality control criteria in whole genome sequencing data set

    PubMed Central

    2014-01-01

    Although the technical and analytic complexity of whole genome sequencing is generally appreciated, best practices for data cleaning and quality control have not been defined. Family based data can be used to guide the standardization of specific quality control metrics in nonfamily based data. Given the low mutation rate, Mendelian inheritance errors are likely as a result of erroneous genotype calls. Thus, our goal was to identify the characteristics that determine Mendelian inheritance errors. To accomplish this, we used chromosome 3 whole genome sequencing family based data from the Genetic Analysis Workshop 18. Mendelian inheritance errors were provided as part of the GAW18 data set. Additionally, for binary variants we calculated Mendelian inheritance errors using PLINK. Based on our analysis, nonbinary single-nucleotide variants have an inherently high number of Mendelian inheritance errors. Furthermore, in binary variants, Mendelian inheritance errors are not randomly distributed. Indeed, we identified 3 Mendelian inheritance error peaks that were enriched with repetitive elements. However, these peaks can be lessened with the inclusion of a single filter from the sequencing file. In summary, we demonstrated that erroneous sequencing calls are nonrandomly distributed across the genome and quality control metrics can dramatically reduce the number of mendelian inheritance errors. Appropriate quality control will allow optimal use of genetic data to realize the full potential of whole genome sequencing. PMID:25519373

  17. The Tukey Honestly Significant Difference Procedure and Its Control of the Type I Error-Rate.

    ERIC Educational Resources Information Center

    Barnette, J. Jackson; McLean, James E.

    Tukey's Honestly Significant Difference (HSD) procedure (J. Tukey, 1953) is probably the most recommended and used procedure for controlling Type I error rate when making multiple pairwise comparisons as follow-ups to a significant omnibus F test. This study compared observed Type I errors with nominal alphas of 0.01, 0.05, and 0.10 compared for…

  18. The Accuracy of Webcams in 2D Motion Analysis: Sources of Error and Their Control

    ERIC Educational Resources Information Center

    Page, A.; Moreno, R.; Candelas, P.; Belmar, F.

    2008-01-01

    In this paper, we show the potential of webcams as precision measuring instruments in a physics laboratory. Various sources of error appearing in 2D coordinate measurements using low-cost commercial webcams are discussed, quantifying their impact on accuracy and precision, and simple procedures to control these sources of error are presented.…

  19. Error mapping controller: a closed loop neuroprosthesis controlled by artificial neural networks

    PubMed Central

    Pedrocchi, Alessandra; Ferrante, Simona; De Momi, Elena; Ferrigno, Giancarlo

    2006-01-01

    Background The design of an optimal neuroprostheses controller and its clinical use presents several challenges. First, the physiological system is characterized by highly inter-subjects varying properties and also by non stationary behaviour with time, due to conditioning level and fatigue. Secondly, the easiness to use in routine clinical practice requires experienced operators. Therefore, feedback controllers, avoiding long setting procedures, are required. Methods The error mapping controller (EMC) here proposed uses artificial neural networks (ANNs) both for the design of an inverse model and of a feedback controller. A neuromuscular model is used to validate the performance of the controllers in simulations. The EMC performance is compared to a Proportional Integral Derivative (PID) included in an anti wind-up scheme (called PIDAW) and to a controller with an ANN as inverse model and a PID in the feedback loop (NEUROPID). In addition tests on the EMC robustness in response to variations of the Plant parameters and to mechanical disturbances are carried out. Results The EMC shows improvements with respect to the other controllers in tracking accuracy, capability to prolong exercise managing fatigue, robustness to parameter variations and resistance to mechanical disturbances. Conclusion Different from the other controllers, the EMC is capable of balancing between tracking accuracy and mapping of fatigue during the exercise. In this way, it avoids overstressing muscles and allows a considerable prolongation of the movement. The collection of the training sets does not require any particular experimental setting and can be introduced in routine clinical practice. PMID:17029636

  20. Effects of locomotion mode recognition errors on volitional control of powered above-knee prostheses.

    PubMed

    Zhang, Fan; Liu, Ming; Huang, He

    2015-01-01

    Recent studies have reported various methods that recognize amputees' intent regarding locomotion modes, which is potentially useful for volitional control of powered artificial legs. However, occasional errors in locomotion mode recognition are inevitable. When these intent recognition decisions are used for volitional prosthesis control, the effects of the decision errors on the operation of the prosthesis and user's task performance is unknown. Hence, the goals of this study were to 1) systematically investigate the effects of locomotion mode recognition errors on volitional control of powered prosthetic legs and the user's gait stability, and 2) identify the critical mode recognition errors that impact safe and confident use of powered artificial legs in lower limb amputees. Five able-bodied subjects and two above-knee (AK) amputees were recruited and tested when wearing a powered AK prosthesis. Four types of locomotion mode recognition errors with different duration and at different gait phases were purposely applied to the prosthesis control. The subjects' gait stabilities were subjectively and objectively quantified. The results showed that not all of the mode recognition errors in volitional prosthesis control disturb the subjects' gait stability. The effects of errors on the user's balance depended on 1) the gait phase when the errors happened and 2) the amount of mechanical work change applied on the powered knee caused by the errors. Based on the study results, "critical errors" were defined and suggested as a new index to evaluate locomotion mode recognition algorithms for artificial legs. The outcome of this study might aid the future design of volitionally-controlled powered prosthetic legs that are reliable and safe for practice.

  1. Error Control Techniques for Satellite and Space Communications

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.

    1996-01-01

    In this report, we present the results of our recent work on turbo coding in two formats. Appendix A includes the overheads of a talk that has been given at four different locations over the last eight months. This presentation has received much favorable comment from the research community and has resulted in the full-length paper included as Appendix B, 'A Distance Spectrum Interpretation of Turbo Codes'. Turbo codes use a parallel concatenation of rate 1/2 convolutional encoders combined with iterative maximum a posteriori probability (MAP) decoding to achieve a bit error rate (BER) of 10(exp -5) at a signal-to-noise ratio (SNR) of only 0.7 dB. The channel capacity for a rate 1/2 code with binary phase shift-keyed modulation on the AWGN (additive white Gaussian noise) channel is 0 dB, and thus the Turbo coding scheme comes within 0.7 DB of capacity at a BER of 10(exp -5).

  2. ADJUSTMENT ERRORS IN ASCENDING AND DESCENDING PHASES OF TARGET LEVEL IN CONTROLLED FORCE EXERTION.

    PubMed

    Kubota, Hiroshi; Demura, Shinichi

    2015-10-01

    Hand grip force adjustment errors to ascending and descending phases of a sinusoidal target force in a controlled force exertion (CFE) test were measured and the laterality of responses evaluated. 75 men (M age = 19.6 yr., SD = 1.6) performed the CFE test after one practice trial by matching handgrip force to target level (5-25% of maximal grip force). The CFE errors in ascending and descending phases of the target force were calculated as the absolute differences between actual force and target force in each phase. There were significantly smaller CFE errors in the ascending phase for both dominant and non-dominant hands, but CFE error for the dominant hand was significantly smaller in both phases. Therefore, error in force exertion in the ascending and descending phases of the target force differed, and laterality influenced error in both phases.

  3. Minimum sliding mode error feedback control for fault tolerant reconfigurable satellite formations with J2 perturbations

    NASA Astrophysics Data System (ADS)

    Cao, Lu; Chen, Xiaoqian; Misra, Arun K.

    2014-03-01

    Minimum Sliding Mode Error Feedback Control (MSMEFC) is proposed to improve the control precision of spacecraft formations based on the conventional sliding mode control theory. This paper proposes a new approach to estimate and offset the system model errors, which include various kinds of uncertainties and disturbances, as well as smoothes out the effect of nonlinear switching control terms. To facilitate the analysis, the concept of equivalent control error is introduced, which is the key to the utilization of MSMEFC. A cost function is formulated on the basis of the principle of minimum sliding mode error; then the equivalent control error is estimated and fed back to the conventional sliding mode control. It is shown that the sliding mode after the MSMEFC will approximate to the ideal sliding mode, resulting in improved control performance and quality. The new methodology is applied to spacecraft formation flying. It guarantees global asymptotic convergence of the relative tracking error in the presence of J2 perturbations. In addition, some fault tolerant situations such as thruster failure for a period of time, thruster degradation and so on, are also considered to verify the effectiveness of MSMEFC. Numerical simulations are performed to demonstrate the efficacy of the proposed methodology to maintain and reconfigure the satellite formation with the existence of initial offsets and J2 perturbation effects, even in the fault-tolerant cases.

  4. One active debris removal control system design and error analysis

    NASA Astrophysics Data System (ADS)

    Wang, Weilin; Chen, Lei; Li, Kebo; Lei, Yongjun

    2016-11-01

    The increasing expansion of debris presents a significant challenge to space safety and sustainability. To address it, active debris removal, usually involving a chaser performing autonomous rendezvous with targeted debris to be removed is a feasible solution. In this paper, we explore a mid-range autonomous rendezvous control system based on augmented proportional navigation (APN), establishing a three-dimensional kinematic equation set constructed in a rotating coordinate system. In APN, feedback control is applied in the direction of line of sight (LOS), thus analytical solutions of LOS rate and relative motion are expectedly obtained. To evaluate the effectiveness of the control system, we adopt Zero-Effort-Miss (ZEM) in this research as the index, the uncertainty of which is directly determined by that of LOS rate. Accordingly, we apply covariance analysis (CA) method to analyze the propagation of LOS rate uncertainty. Consequently, we find that the accuracy of the control system can be verified even with uncertainty and the CA method is drastically more computationally efficient compared with nonlinear Monte-Carlo method. Additionally, to justify the superiority of the system, we further discuss more simulation cases to show the robustness and feasibility of APN proposed in the paper.

  5. An analysis of control reversal errors during unusual attitude recoveries using helmet-mounted display symbology.

    PubMed

    Liggett, Kristen K; Gallimore, Jennie J

    2002-02-01

    Spatial disorientation (SD) refers to pilots' inability to accurately interpret the attitude of their aircraft with respect to Earth. Unfortunately, SD statistics have held constant for the past few decades, through the transition from the head-down attitude indicator (Al) to the head-up display (HUD) as the attitude instrument. The newest attitude-indicating device to find its way into military cockpits is the helmet-mounted display (HMD). HMDs were initially introduced into the cockpit to enhance target location and weapon-pointing, but there is currently an effort to make HMDs attitude reference displays so pilots need not go head-down to obtain attitude information. However, unintuitive information or inappropriate implementation of on-boresight attitude symbology on the HMD may contribute to the SD problem. The occurrence of control reversal errors (CREs) during unusual attitude recovery tasks when using an HMD to provide attitude information was investigated. The effect of such errors was evaluated in terms of altitude changes during recovery and time to recover. There were 12 pilot-subjects who completed 8 unusual attitude recovery tasks. Results showed that CREs did occur, and there was a significant negative effect of these errors on absolute altitude change, but not on total recovery time. Results failed to show a decrease in the number of CREs occurring when using the HMD as compared with data from other studies that used an Al or a HUD. Results suggest that new HMD attitude symbology needs to be designed to help reduce CREs and, perhaps, SD incidences.

  6. Analysis of Covariance with Linear Regression Error Model on Antenna Control Unit Tracking

    DTIC Science & Technology

    2015-10-20

    412TW-PA-15238 Analysis of Covariance with Linear Regression Error Model on Antenna Control Unit Tracking DANIEL T. LAIRD AIR...COVERED (From - To) 20 OCT 15 – 23 OCT 15 4. TITLE AND SUBTITLE Analysis of Covariance with Linear Regression Error Model on Antenna Control Tracking...supplement technical expertise, rather than rely solely on expertise, which is subjective. In this paper we apply linear regression modeling and

  7. NASA Iced Aerodynamics and Controls Current Research

    NASA Technical Reports Server (NTRS)

    Addy, Gene

    2009-01-01

    This slide presentation reviews the state of current research in the area of aerodynamics and aircraft control with ice conditions by the Aviation Safety Program, part of the Integrated Resilient Aircraft Controls Project (IRAC). Included in the presentation is a overview of the modeling efforts. The objective of the modeling is to develop experimental and computational methods to model and predict aircraft response during adverse flight conditions, including icing. The Aircraft icing modeling efforts includes the Ice-Contaminated Aerodynamics Modeling, which examines the effects of ice contamination on aircraft aerodynamics, and CFD modeling of ice-contaminated aircraft aerodynamics, and Advanced Ice Accretion Process Modeling which examines the physics of ice accretion, and works on computational modeling of ice accretions. The IRAC testbed, a Generic Transport Model (GTM) and its use in the investigation of the effects of icing on its aerodynamics is also reviewed. This has led to a more thorough understanding and models, both theoretical and empirical of icing physics and ice accretion for airframes, advanced 3D ice accretion prediction codes, CFD methods for iced aerodynamics and better understanding of aircraft iced aerodynamics and its effects on control surface effectiveness.

  8. Suspended sediment fluxes in a tidal wetland: Measurement, controlling factors, and error analysis

    USGS Publications Warehouse

    Ganju, N.K.; Schoellhamer, D.H.; Bergamaschi, B.A.

    2005-01-01

    Suspended sediment fluxes to and from tidal wetlands are of increasing concern because of habitat restoration efforts, wetland sustainability as sea level rises, and potential contaminant accumulation. We measured water and sediment fluxes through two channels on Browns Island, at the landward end of San Francisco Bay, United States, to determine the factors that control sediment fluxes on and off the island. In situ instrumentation was deployed between October 10 and November 13, 2003. Acoustic Doppler current profilers and the index velocity method were employed to calculate water fluxes. Suspended sediment concentrations (SSC) were determined with optical sensors and cross-sectional water sampling. All procedures were analyzed for their contribution to total error in the flux measurement. The inability to close the water balance and determination of constituent concentration were identified as the main sources of error; total error was 27% for net sediment flux. The water budget for the island was computed with an unaccounted input of 0.20 m 3 s-1 (22% of mean inflow), after considering channel flow, change in water storage, evapotranspiration, and precipitation. The net imbalance may be a combination of groundwater seepage, overland flow, and flow through minor channels. Change of island water storage, caused by local variations in water surface elevation, dominated the tidalty averaged water flux. These variations were mainly caused by wind and barometric pressure change, which alter regional water levels throughout the Sacramento-San Joaquin River Delta. Peak instantaneous ebb flow was 35% greater than peak flood flow, indicating an ebb-dominant system, though dominance varied with the spring-neap cycle. SSC were controlled by wind-wave resuspension adjacent to the island and local tidal currents that mobilized sediment from the channel bed. During neap tides sediment was imported onto the island but during spring tides sediment was exported because the main

  9. Early error detection predicted by reduced pre-response control process: an ERP topographic mapping study.

    PubMed

    Pourtois, Gilles

    2011-01-01

    Advanced ERP topographic mapping techniques were used to study error monitoring functions in human adult participants, and test whether proactive attentional effects during the pre-response time period could later influence early error detection mechanisms (as measured by the ERN component) or not. Participants performed a speeded go/nogo task, and made a substantial number of false alarms that did not differ from correct hits as a function of behavioral speed or actual motor response. While errors clearly elicited an ERN component generated within the dACC following the onset of these incorrect responses, I also found that correct hits were associated with a different sequence of topographic events during the pre-response baseline time-period, relative to errors. A main topographic transition from occipital to posterior parietal regions (including primarily the precuneus) was evidenced for correct hits ~170-150 ms before the response, whereas this topographic change was markedly reduced for errors. The same topographic transition was found for correct hits that were eventually performed slower than either errors or fast (correct) hits, confirming the involvement of this distinctive posterior parietal activity in top-down attentional control rather than motor preparation. Control analyses further ensured that this pre-response topographic effect was not related to differences in stimulus processing. Furthermore, I found a reliable association between the magnitude of the ERN following errors and the duration of this differential precuneus activity during the pre-response baseline, suggesting a functional link between an anticipatory attentional control component subserved by the precuneus and early error detection mechanisms within the dACC. These results suggest reciprocal links between proactive attention control and decision making processes during error monitoring.

  10. Flux control coefficients determined by inhibitor titration: the design and analysis of experiments to minimize errors.

    PubMed Central

    Small, J R

    1993-01-01

    This paper is a study into the effects of experimental error on the estimated values of flux control coefficients obtained using specific inhibitors. Two possible techniques for analysing the experimental data are compared: a simple extrapolation method (the so-called graph method) and a non-linear function fitting method. For these techniques, the sources of systematic errors are identified and the effects of systematic and random errors are quantified, using both statistical analysis and numerical computation. It is shown that the graph method is very sensitive to random errors and, under all conditions studied, that the fitting method, even under conditions where the assumptions underlying the fitted function do not hold, outperformed the graph method. Possible ways of designing experiments to minimize the effects of experimental errors are analysed and discussed. PMID:8257434

  11. Real-time modeling and online filtering of the stochastic error in a fiber optic current transducer

    NASA Astrophysics Data System (ADS)

    Wang, Lihui; Wei, Guangjin; Zhu, Yunan; Liu, Jian; Tian, Zhengqi

    2016-10-01

    The stochastic error characteristics of a fiber optic current transducer (FOCT) influence the relay protection, electric-energy metering, and other devices in the spacer layer. Real-time modeling and online filtering of the FOCT’s stochastic error tends to be an effective method for improving the measurement accuracy of the FOCT. This paper first pretreats and inspects the FOCT data, statistically. Then, the model order is set by the AIC principle to establish an ARMA (2,1) model and model’s applicability is tested. Finally, a Kalman filter is adopted to reduce the noise in the FOCT data. The results of the experiment and the simulation demonstrate that there is a notable decrease in the stochastic error after time series modeling and Kalman filtering. Besides, the mean-variance is decreased by two orders. All the stochastic error coefficients are decreased by the total variance method; the BI is decreased by 41.4%, the RRW is decreased by 67.5%, and the RR is decreased by 53.4%. Consequently, the method can reduce the stochastic error and improve the measurement accuracy of the FOCT, effectively.

  12. Myopia and models and mechanisms of refractive error control.

    PubMed

    Lawrence, Matthew S; Azar, Dimitri T

    2002-03-01

    Myopia represents a failure of the normal process of emmetropization, which is essentially endogenous to the eye. Emmetropization involves defocus detection at the level of the amacrine and bipolar cells of the outer retina, diffusion of a signal or signals across the retinal pigment epithelium and choroid, and alteration of the scleral matrix, likely through modulation of proteoglycan synthesis. Elucidating and effectively bolstering the deficient steps in this regulatory pathway would mark a significant advance given myopia's tremendous impact. Clinical experience, longitudinal studies, epidemiological data and numerous animal experiments have enhanced our understanding of myopia. Interpretation of the epidemiological data is often complicated by the difficulties of distinguishing environmental from genetic influences, especially those pertaining to slow developmental changes. Likewise, it is important that the animal models be interpreted with an appreciation that the human eye varies structurally and developmentally from that of other species. Studies of the chick eye have formed the basis for several hypotheses of myopic development, but the chick does not possess a fovea or retinal blood supply. It is unclear whether these differences alter the pathways of emmetropization. Even closely related primate species can exhibit different responses to form deprivation conditions, suggesting differing mechanisms of eye growth control. Monocular occlusion of the rhesus macaque, for instance, results in myopia when the ciliary muscle is paralyzed or the optic nerve cut, but does not in the stumptailed macaque, suggesting a role of excessive accommodation in the development of myopia in the stumptail but not the rhesus [36]. Given such variability in the models a persisting element of continued myopia research must be an evaluation of the relevance of any given model to the human condition. In this regard, the study of changing patterns of gene expression within and

  13. Data Entry Errors and Design for Model-Based Tight Glycemic Control in Critical Care

    PubMed Central

    Ward, Logan; Steel, James; Le Compte, Aaron; Evans, Alicia; Tan, Chia-Siong; Penning, Sophie; Shaw, Geoffrey M; Desaive, Thomas; Chase, J Geoffrey

    2012-01-01

    Introduction Tight glycemic control (TGC) has shown benefits but has been difficult to achieve consistently. Model-based methods and computerized protocols offer the opportunity to improve TGC quality but require human data entry, particularly of blood glucose (BG) values, which can be significantly prone to error. This study presents the design and optimization of data entry methods to minimize error for a computerized and model-based TGC method prior to pilot clinical trials. Method To minimize data entry error, two tests were carried out to optimize a method with errors less than the 5%-plus reported in other studies. Four initial methods were tested on 40 subjects in random order, and the best two were tested more rigorously on 34 subjects. The tests measured entry speed and accuracy. Errors were reported as corrected and uncorrected errors, with the sum comprising a total error rate. The first set of tests used randomly selected values, while the second set used the same values for all subjects to allow comparisons across users and direct assessment of the magnitude of errors. These research tests were approved by the University of Canterbury Ethics Committee. Results The final data entry method tested reduced errors to less than 1–2%, a 60–80% reduction from reported values. The magnitude of errors was clinically significant and was typically by 10.0 mmol/liter or an order of magnitude but only for extreme values of BG < 2.0 mmol/liter or BG > 15.0–20.0 mmol/liter, both of which could be easily corrected with automated checking of extreme values for safety. Conclusions The data entry method selected significantly reduced data entry errors in the limited design tests presented, and is in use on a clinical pilot TGC study. The overall approach and testing methods are easily performed and generalizable to other applications and protocols. PMID:22401331

  14. Review of current GPS methodologies for producing accurate time series and their error sources

    NASA Astrophysics Data System (ADS)

    He, Xiaoxing; Montillet, Jean-Philippe; Fernandes, Rui; Bos, Machiel; Yu, Kegen; Hua, Xianghong; Jiang, Weiping

    2017-05-01

    The Global Positioning System (GPS) is an important tool to observe and model geodynamic processes such as plate tectonics and post-glacial rebound. In the last three decades, GPS has seen tremendous advances in the precision of the measurements, which allow researchers to study geophysical signals through a careful analysis of daily time series of GPS receiver coordinates. However, the GPS observations contain errors and the time series can be described as the sum of a real signal and noise. The signal itself can again be divided into station displacements due to geophysical causes and to disturbing factors. Examples of the latter are errors in the realization and stability of the reference frame and corrections due to ionospheric and tropospheric delays and GPS satellite orbit errors. There is an increasing demand on detecting millimeter to sub-millimeter level ground displacement signals in order to further understand regional scale geodetic phenomena hence requiring further improvements in the sensitivity of the GPS solutions. This paper provides a review spanning over 25 years of advances in processing strategies, error mitigation methods and noise modeling for the processing and analysis of GPS daily position time series. The processing of the observations is described step-by-step and mainly with three different strategies in order to explain the weaknesses and strengths of the existing methodologies. In particular, we focus on the choice of the stochastic model in the GPS time series, which directly affects the estimation of the functional model including, for example, tectonic rates, seasonal signals and co-seismic offsets. Moreover, the geodetic community continues to develop computational methods to fully automatize all phases from analysis of GPS time series. This idea is greatly motivated by the large number of GPS receivers installed around the world for diverse applications ranging from surveying small deformations of civil engineering structures (e

  15. Design, performance, and calculated error of a Faraday cup for absolute beam current measurements of 600-MeV protons

    NASA Technical Reports Server (NTRS)

    Beck, S. M.

    1975-01-01

    A mobile self-contained Faraday cup system for beam current measurments of nominal 600 MeV protons was designed, constructed, and used at the NASA Space Radiation Effects Laboratory. The cup is of reentrant design with a length of 106.7 cm and an outside diameter of 20.32 cm. The inner diameter is 15.24 cm and the base thickness is 30.48 cm. The primary absorber is commercially available lead hermetically sealed in a 0.32-cm-thick copper jacket. Several possible systematic errors in using the cup are evaluated. The largest source of error arises from high-energy electrons which are ejected from the entrance window and enter the cup. A total systematic error of -0.83 percent is calculated to be the decrease from the true current value. From data obtained in calibrating helium-filled ion chambers with the Faraday cup, the mean energy required to produce one ion pair in helium is found to be 30.76 + or - 0.95 eV for nominal 600 MeV protons. This value agrees well, within experimental error, with reported values of 29.9 eV and 30.2 eV.

  16. Error tracking control for underactuated overhead cranes against arbitrary initial payload swing angles

    NASA Astrophysics Data System (ADS)

    Zhang, Menghua; Ma, Xin; Rong, Xuewen; Tian, Xincheng; Li, Yibin

    2017-02-01

    This paper exploits an error tracking control method for overhead crane systems for which the error trajectories for the trolley and the payload swing can be pre-specified. The proposed method does not require that the initial payload swing angle remains zero, whereas this requirement is usually assumed in conventional methods. The significant feature of the proposed method is its superior control performance as well as its strong robustness over different or uncertain rope lengths, payload masses, desired positions, initial payload swing angles, and external disturbances. Owing to the same attenuation behavior, the desired error trajectory for the trolley for each traveling distance is not needed to be reset, which is easy to implement in practical applications. By converting the error tracking overhead crane dynamics to the objective system, we obtain the error tracking control law for arbitrary initial payload swing angles. Lyapunov techniques and LaSalle's invariance theorem are utilized to prove the convergence and stability of the closed-loop system. Simulation and experimental results are illustrated to validate the superior performance of the proposed error tracking control method.

  17. [Statistical Process Control (SPC) can help prevent treatment errors without increasing costs in radiotherapy].

    PubMed

    Govindarajan, R; Llueguera, E; Melero, A; Molero, J; Soler, N; Rueda, C; Paradinas, C

    2010-01-01

    Statistical Process Control (SPC) was applied to monitor patient set-up in radiotherapy and, when the measured set-up error values indicated a loss of process stability, its root cause was identified and eliminated to prevent set-up errors. Set up errors were measured for medial-lateral (ml), cranial-caudal (cc) and anterior-posterior (ap) dimensions and then the upper control limits were calculated. Once the control limits were known and the range variability was acceptable, treatment set-up errors were monitored using sub-groups of 3 patients, three times each shift. These values were plotted on a control chart in real time. Control limit values showed that the existing variation was acceptable. Set-up errors, measured and plotted on a X chart, helped monitor the set-up process stability and, if and when the stability was lost, treatment was interrupted, the particular cause responsible for the non-random pattern was identified and corrective action was taken before proceeding with the treatment. SPC protocol focuses on controlling the variability due to assignable cause instead of focusing on patient-to-patient variability which normally does not exist. Compared to weekly sampling of set-up error in each and every patient, which may only ensure that just those sampled sessions were set-up correctly, the SPC method enables set-up error prevention in all treatment sessions for all patients and, at the same time, reduces the control costs. Copyright © 2009 SECA. Published by Elsevier Espana. All rights reserved.

  18. Automatic Time Stepping with Global Error Control for Groundwater Flow Models

    SciTech Connect

    Tang, Guoping

    2008-09-01

    An automatic time stepping with global error control is proposed for the time integration of the diffusion equation to simulate groundwater flow in confined aquifers. The scheme is based on an a posteriori error estimate for the discontinuous Galerkin (dG) finite element methods. A stability factor is involved in the error estimate and it is used to adapt the time step and control the global temporal error for the backward difference method. The stability factor can be estimated by solving a dual problem. The stability factor is not sensitive to the accuracy of the dual solution and the overhead computational cost can be minimized by solving the dual problem using large time steps. Numerical experiments are conducted to show the application and the performance of the automatic time stepping scheme. Implementation of the scheme can lead to improvement in accuracy and efficiency for groundwater flow models.

  19. An error criterion for determining sampling rates in closed-loop control systems

    NASA Technical Reports Server (NTRS)

    Brecher, S. M.

    1972-01-01

    The determination of an error criterion which will give a sampling rate for adequate performance of linear, time-invariant closed-loop, discrete-data control systems was studied. The proper modelling of the closed-loop control system for characterization of the error behavior, and the determination of an absolute error definition for performance of the two commonly used holding devices are discussed. The definition of an adequate relative error criterion as a function of the sampling rate and the parameters characterizing the system is established along with the determination of sampling rates. The validity of the expressions for the sampling interval was confirmed by computer simulations. Their application solves the problem of making a first choice in the selection of sampling rates.

  20. Error Control with Perfectly Matched Layer or Damping Layer Treatments for Computational Aeroacoustics with Jet Flows

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    2009-01-01

    In this paper we show by means of numerical experiments that the error introduced in a numerical domain because of a Perfectly Matched Layer or Damping Layer boundary treatment can be controlled. These experimental demonstrations are for acoustic propagation with the Linearized Euler Equations with both uniform and steady jet flows. The propagating signal is driven by a time harmonic pressure source. Combinations of Perfectly Matched and Damping Layers are used with different damping profiles. These layer and profile combinations allow the relative error introduced by a layer to be kept as small as desired, in principle. Tradeoffs between error and cost are explored.

  1. A parity retransmission hybrid ARQ using a convolutional code and Viterbi decoding for error control

    NASA Astrophysics Data System (ADS)

    Lin, S.; Wang, Y.-M.

    In this paper a parity retransmission hybrid ARQ scheme which employs a convolutional code and Viterbi decoding for error correction is presented. The proposed parity retransmission hybrid ARQ in selective-repeat mode is analyzed for a binary symmetry channel. A lower bound on the throughput efficiency for any finite size of receiver buffer is obtained. An upper bound on the error probability is also obtained. The proposed scheme is particularly attractive for error control in data communication systems where data rate is high and round-trip delay is large, such as in satellite communications.

  2. EMG versus torque control of human-machine systems: equalizing control signal variability does not equalize error or uncertainty.

    PubMed

    Johnson, Reva E; Koerding, Konrad P; Hargrove, Levi J; Sensinger, Jonathon W

    2016-08-25

    In this paper we asked the question: if we artificially raise the variability of torque control signals to match that of EMG, do subjects make similar errors and have similar uncertainty about their movements? We answered this question using two experiments in which subjects used three different control signals: torque, torque+noise, and EMG. First, we measured error on a simple target-hitting task in which subjects received visual feedback only at the end of their movements. We found that even when the signal-to-noise ratio was equal across EMG and torque+noise control signals, EMG resulted in larger errors. Second, we quantified uncertainty by measuring the just-noticeable difference of a visual perturbation. We found that for equal errors, EMG resulted in higher movement uncertainty than both torque and torque+noise. The differences suggest that performance and confidence are influenced by more than just the noisiness of the control signal, and suggest that other factors, such as the user's ability to incorporate feedback and develop accurate internal models, also have significant impacts on the performance and confidence of a person's actions. We theorize that users have difficulty distinguishing between random and systematic errors for EMG control, and future work should examine in more detail the types of errors made with EMG control.

  3. Higher order feed-forward control of reticle writing error fingerprints

    NASA Astrophysics Data System (ADS)

    van Haren, Richard; Cekli, Hakki Ergun; Beltman, Jan; Pastol, Anne; Sundermann, Frank; Gatefait, Maxime

    2015-10-01

    The understanding and control of the intra-field overlay budget becomes crucial particularly after the introduction of multi-patterning applications. The intra-field overlay budget is built-up out of many contributors, each with its own characteristic. Some of them are (semi-)static like the reticle writing error (RWE) fingerprint, the scanner lens fingerprint, or the intra-field processing signature. Others are more dynamic. Examples are reticle heating and lens heating due to the absorption of a small portion of the exposure light. Ideally, all overlay contributors that are understood and known could be taken out of the feed-back control loop and send as feed-forward corrections to the scanner. As a consequence, only non-correctable overlay residuals are measured on the wafer. In the current work, we have studied the possibility to characterize the reticle writing error fingerprint by an off-line position measurement tool and use this information to send feed-forward corrections to the ASML TWINSCANTM exposure tool. The current work is an extension of the work we published earlier. To this end, we have selected a reticle pair out of 50 production reticles that are used to manufacture a 28-nm technology device. These two reticles are special in the sense that the delta fingerprint contains a significant higher order RWE signature. While previously only the linear parameters were sent as feed-forward corrections to the ASML TWINSCANTM exposure tool, this time we additionally demonstrate the capability to correct for the non-linear terms as well. Since the concept heavily relies on the quality of the off-line mask registration measurements, a state-of-the-art reticle registration tool was chosen. Special care was taken to eliminate any effects of the tool induced shifts that may affect the quality of the measurements. The on-wafer overlay verification measurements were performed on an ASML YieldStar metrology tool as well as on a different vendor tool. In conclusion

  4. A parallel row-based algorithm for standard cell placement with integrated error control

    NASA Technical Reports Server (NTRS)

    Sargent, Jeff S.; Banerjee, Prith

    1989-01-01

    A new row-based parallel algorithm for standard-cell placement targeted for execution on a hypercube multiprocessor is presented. Key features of this implementation include a dynamic simulated-annealing schedule, row-partitioning of the VLSI chip image, and two novel approaches to control error in parallel cell-placement algorithms: (1) Heuristic Cell-Coloring; (2) Adaptive Sequence Length Control.

  5. Adjoint-field errors in high fidelity compressible turbulence simulations for sound control

    NASA Astrophysics Data System (ADS)

    Vishnampet, Ramanathan; Bodony, Daniel; Freund, Jonathan

    2013-11-01

    A consistent discrete adjoint for high-fidelity discretization of the three-dimensional Navier-Stokes equations is used to quantify the error in the sensitivity gradient predicted by the continuous adjoint method, and examine the aeroacoustic flow-control problem for free-shear-flow turbulence. A particular quadrature scheme for approximating the cost functional makes our discrete adjoint formulation for a fourth-order Runge-Kutta scheme with high-order finite differences practical and efficient. The continuous adjoint-based sensitivity gradient is shown to to be inconsistent due to discretization truncation errors, grid stretching and filtering near boundaries. These errors cannot be eliminated by increasing the spatial or temporal resolution since chaotic interactions lead them to become O (1) at the time of control actuation. Although this is a known behavior for chaotic systems, its effect on noise control is much harder to anticipate, especially given the different resolution needs of different parts of the turbulence and acoustic spectra. A comparison of energy spectra of the adjoint pressure fields shows significant error in the continuous adjoint at all wavenumbers, even though they are well-resolved. The effect of this error on the noise control mechanism is analyzed.

  6. Effects of modeling errors on trajectory predictions in air traffic control automation

    NASA Technical Reports Server (NTRS)

    Jackson, Michael R. C.; Zhao, Yiyuan; Slattery, Rhonda

    1996-01-01

    Air traffic control automation synthesizes aircraft trajectories for the generation of advisories. Trajectory computation employs models of aircraft performances and weather conditions. In contrast, actual trajectories are flown in real aircraft under actual conditions. Since synthetic trajectories are used in landing scheduling and conflict probing, it is very important to understand the differences between computed trajectories and actual trajectories. This paper examines the effects of aircraft modeling errors on the accuracy of trajectory predictions in air traffic control automation. Three-dimensional point-mass aircraft equations of motion are assumed to be able to generate actual aircraft flight paths. Modeling errors are described as uncertain parameters or uncertain input functions. Pilot or autopilot feedback actions are expressed as equality constraints to satisfy control objectives. A typical trajectory is defined by a series of flight segments with different control objectives for each flight segment and conditions that define segment transitions. A constrained linearization approach is used to analyze trajectory differences caused by various modeling errors by developing a linear time varying system that describes the trajectory errors, with expressions to transfer the trajectory errors across moving segment transitions. A numerical example is presented for a complete commercial aircraft descent trajectory consisting of several flight segments.

  7. Systematic sparse matrix error control for linear scaling electronic structure calculations.

    PubMed

    Rubensson, Emanuel H; Sałek, Paweł

    2005-11-30

    Efficient truncation criteria used in multiatom blocked sparse matrix operations for ab initio calculations are proposed. As system size increases, so does the need to stay on top of errors and still achieve high performance. A variant of a blocked sparse matrix algebra to achieve strict error control with good performance is proposed. The presented idea is that the condition to drop a certain submatrix should depend not only on the magnitude of that particular submatrix, but also on which other submatrices that are dropped. The decision to remove a certain submatrix is based on the contribution the removal would cause to the error in the chosen norm. We study the effect of an accumulated truncation error in iterative algorithms like trace correcting density matrix purification. One way to reduce the initial exponential growth of this error is presented. The presented error control for a sparse blocked matrix toolbox allows for achieving optimal performance by performing only necessary operations needed to maintain the requested level of accuracy. Copyright 2005 Wiley Periodicals, Inc.

  8. AfterQC: automatic filtering, trimming, error removing and quality control for fastq data.

    PubMed

    Chen, Shifu; Huang, Tanxiao; Zhou, Yanqing; Han, Yue; Xu, Mingyan; Gu, Jia

    2017-03-14

    Some applications, especially those clinical applications requiring high accuracy of sequencing data, usually have to face the troubles caused by unavoidable sequencing errors. Several tools have been proposed to profile the sequencing quality, but few of them can quantify or correct the sequencing errors. This unmet requirement motivated us to develop AfterQC, a tool with functions to profile sequencing errors and correct most of them, plus highly automated quality control and data filtering features. Different from most tools, AfterQC analyses the overlapping of paired sequences for pair-end sequencing data. Based on overlapping analysis, AfterQC can detect and cut adapters, and furthermore it gives a novel function to correct wrong bases in the overlapping regions. Another new feature is to detect and visualise sequencing bubbles, which can be commonly found on the flowcell lanes and may raise sequencing errors. Besides normal per cycle quality and base content plotting, AfterQC also provides features like polyX (a long sub-sequence of a same base X) filtering, automatic trimming and K-MER based strand bias profiling. For each single or pair of FastQ files, AfterQC filters out bad reads, detects and eliminates sequencer's bubble effects, trims reads at front and tail, detects the sequencing errors and corrects part of them, and finally outputs clean data and generates HTML reports with interactive figures. AfterQC can run in batch mode with multiprocess support, it can run with a single FastQ file, a single pair of FastQ files (for pair-end sequencing), or a folder for all included FastQ files to be processed automatically. Based on overlapping analysis, AfterQC can estimate the sequencing error rate and profile the error transform distribution. The results of our error profiling tests show that the error distribution is highly platform dependent. Much more than just another new quality control (QC) tool, AfterQC is able to perform quality control, data

  9. An investigation into the milliarcsecond attitude control errors of Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Bradley, A. J.; Chapman, R. D.; Kalinowski, J. K.; Kimmer, E.; Welter, G.; Whittier, W.

    1997-01-01

    An analysis of the fine pointing errors of the Hubble Space Telescope (HST), in the range from 1 to 15 milliarcsecs, is reported on. The emphasis is on the study of the performance characteristics of the pointing control system, fine guidance sensors and the optical telescope assembly, which produce relative attitude and astrometric measurement errors. Since the first servicing mission in December 1993, the HST relative short term position stability is of the order of 3 milliarcsecs RMS when averaged over 1 min intervals. At this level of accuracy, longer term systematic attitude errors in this range can have a noticeable impact on the telescope's observations. The various error sources are described, including: internal temperature effects; spacecraft structure temperature effects; calibration procedures, and computational inaccuracies.

  10. A hybrid ARQ scheme with parity retransmission for error control of satellite channels

    NASA Astrophysics Data System (ADS)

    Lin, S.; Yu, P. S.

    1982-07-01

    A novel type of hybrid automatic-repeat-request (ARQ) scheme for error control in data communication systems is described which is based on the sending of parity check digits for error correction to the receiver only when they are needed. When a data block D is detected to be in error, the retransmissions are alternate repetitions of a parity block P(D) and D. When a parity block is received, it is used to recover the originally transmitted data block either by inversion or by decoding operation. The repetitions of P(D) and D are alternately stored in the receiver buffer for error correction until D is recovered. It is shown that the hybrid ARQ scheme proposed offers both high throughput and high system reliability, being especially useful in high speed data communication systems with significant roundtrip delays, such as those encountered in satellite channels.

  11. Modeling SMAP Spacecraft Attitude Control Estimation Error Using Signal Generation Model

    NASA Technical Reports Server (NTRS)

    Rizvi, Farheen

    2016-01-01

    Two ground simulation software are used to model the SMAP spacecraft dynamics. The CAST software uses a higher fidelity model than the ADAMS software. The ADAMS software models the spacecraft plant, controller and actuator models, and assumes a perfect sensor and estimator model. In this simulation study, the spacecraft dynamics results from the ADAMS software are used as CAST software is unavailable. The main source of spacecraft dynamics error in the higher fidelity CAST software is due to the estimation error. A signal generation model is developed to capture the effect of this estimation error in the overall spacecraft dynamics. Then, this signal generation model is included in the ADAMS software spacecraft dynamics estimate such that the results are similar to CAST. This signal generation model has similar characteristics mean, variance and power spectral density as the true CAST estimation error. In this way, ADAMS software can still be used while capturing the higher fidelity spacecraft dynamics modeling from CAST software.

  12. Controlling local currents in molecular junctions

    NASA Astrophysics Data System (ADS)

    Yadalam, Hari Kumar; Harbola, Upendra

    2016-09-01

    The effects of nonequilibrium constraints and dephasing on the circulating currents in molecular junctions are analyzed. Circulating currents are manifestations of quantum effects and can be induced either by externally applied bias or an external magnetic field through the molecular system. In a symmetric Aharonov-Bohm ring, bond currents have two contributions, bias driven and magnetic field driven. We analyze the competition between these two contributions and show that, as a consequence, current through one of the branches can be completely suppressed. We then study the effect of asymmetry (as a result of chemical substitution) on the current pathways inside the molecule and study asymmetry-induced circulating currents (without magnetic field) by tuning the coupling strength of the substituent (at finite bias).

  13. Robust Integral of Neural Network and Error Sign Control of MIMO Nonlinear Systems.

    PubMed

    Yang, Qinmin; Jagannathan, Sarangapani; Sun, Youxian

    2015-12-01

    This paper presents a novel state-feedback control scheme for the tracking control of a class of multi-input multioutput continuous-time nonlinear systems with unknown dynamics and bounded disturbances. First, the control law consisting of the robust integral of a neural network (NN) output plus sign of the tracking error feedback multiplied with an adaptive gain is introduced. The NN in the control law learns the system dynamics in an online manner, while the NN residual reconstruction errors and the bounded disturbances are overcome by the error sign signal. Since both of the NN output and the error sign signal are included in the integral, the continuity of the control input is ensured. The controller structure and the NN weight update law are novel in contrast with the previous effort, and the semiglobal asymptotic tracking performance is still guaranteed by using the Lyapunov analysis. In addition, the NN weights and all other signals are proved to be bounded simultaneously. The proposed approach also relaxes the need for the upper bounds of certain terms, which are usually required in the previous designs. Finally, the theoretical results are substantiated with simulations.

  14. PD plus error-dependent integral nonlinear controllers for robot manipulators with an uncertain Jacobian matrix.

    PubMed

    Huang, C Q; Xie, L F; Liu, Y L

    2012-11-01

    In framework of traditional PID controllers, there are only three parameters available to tune, as a result, performance of the resulting system is always limited. As for Cartesian regulation of robot manipulators with uncertain Jacobian matrix, a scheme of PID controllers with error-dependent integral action is proposed. Compare with traditional PID controllers, the error-dependent integration is employed in the proposed PID controller, in which more parameters are available to be tuned. It provides additional flexibility for controller characteristics and tuning as well, and hence makes better transient performance. In addition, asymptotic stability of the resulting closed-loop system is guaranteed. All signals in the system are bounded when exogenous disturbances and measurement noises are bounded. Numerical example demonstrates the superior transient performance of the proposed controller over the traditional one via Cartesian space set-point manipulation of two-link robotic manipulator. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

  15. Predicting Human Error in Air Traffic Control Decision Support Tools and Free Flight Concepts

    NASA Technical Reports Server (NTRS)

    Mogford, Richard; Kopardekar, Parimal

    2001-01-01

    The document is a set of briefing slides summarizing the work the Advanced Air Transportation Technologies (AATT) Project is doing on predicting air traffic controller and airline pilot human error when using new decision support software tools and when involved in testing new air traffic control concepts. Previous work in this area is reviewed as well as research being done jointly with the FAA. Plans for error prediction work in the AATT Project are discussed. The audience is human factors researchers and aviation psychologists from government and industry.

  16. Predicting Human Error in Air Traffic Control Decision Support Tools and Free Flight Concepts

    NASA Technical Reports Server (NTRS)

    Mogford, Richard; Kopardekar, Parimal

    2001-01-01

    The document is a set of briefing slides summarizing the work the Advanced Air Transportation Technologies (AATT) Project is doing on predicting air traffic controller and airline pilot human error when using new decision support software tools and when involved in testing new air traffic control concepts. Previous work in this area is reviewed as well as research being done jointly with the FAA. Plans for error prediction work in the AATT Project are discussed. The audience is human factors researchers and aviation psychologists from government and industry.

  17. SEMICONDUCTOR INTEGRATED CIRCUITS A 12-bit current steering DAC with 2-dimensional gradient-error tolerant switching scheme

    NASA Astrophysics Data System (ADS)

    Hao, Chen; Liyuan, Liu; Dongmei, Li; Chun, Zhang; Zhihua, Wang

    2010-10-01

    A 12-bit intrinsic accuracy digital-to-analog converter integrated into standard digital 0.18 μm CMOS technology is proposed. It is based on a current steering segmented 6+6 architecture and requires no calibration. By dividing one most significant bit unary source into 16 elements located in 16 separated regions of the array, the linear gradient errors and quadratic errors can be averaged and eliminated effectively. A novel static performance testing method is proposed. The measured differential nonlinearity and integral nonlinearity are 0.42 and 0.39 least significant bit, respectively. For 12-bit resolution, the converter reaches an update rate of 100 MS/s. The chip operates from a single 1.8 V voltage supply, and the core die area is 0.28 mm2.

  18. Combustion Control of Diesel Engine using Feedback Error Learning with Kernel Online Learning Approach

    NASA Astrophysics Data System (ADS)

    Widayaka, Elfady Satya; Ohmori, Hiromitsu

    2016-09-01

    This paper shows how to design Multivariable Model Reference Adaptive Control System (MRACS) for “Tokyo University discrete-time engine model” proposed by Yasuda et al (2014). This controller configuration has the structure of “Feedback error learning (FEL)” and adaptive law is based on kernel method. Simulation results indicate that “kernelized” adaptive controllers can improve the tracking performance, the speed of convergence and the robustness to disturbances.

  19. Effect of gyro verticality error on lateral autoland tracking performance for an inertially smoothed control law

    NASA Technical Reports Server (NTRS)

    Thibodeaux, J. J.

    1977-01-01

    The results of a simulation study performed to determine the effects of gyro verticality error on lateral autoland tracking and landing performance are presented. A first order vertical gyro error model was used to generate the measurement of the roll attitude feedback signal normally supplied by an inertial navigation system. The lateral autoland law used was an inertially smoothed control design. The effect of initial angular gyro tilt errors (2 deg, 3 deg, 4 deg, and 5 deg), introduced prior to localizer capture, were investigated by use of a small perturbation aircraft simulation. These errors represent the deviations which could occur in the conventional attitude sensor as a result of the maneuver-induced spin-axis misalinement and drift. Results showed that for a 1.05 deg per minute erection rate and a 5 deg initial tilt error, ON COURSE autoland control logic was not satisfied. Failure to attain the ON COURSE mode precluded high control loop gains and localizer beam path integration and resulted in unacceptable beam standoff at touchdown.

  20. Cognitive Impairments in Occupational Burnout - Error Processing and Its Indices of Reactive and Proactive Control.

    PubMed

    Golonka, Krystyna; Mojsa-Kaja, Justyna; Gawlowska, Magda; Popiel, Katarzyna

    2017-01-01

    The presented study refers to cognitive aspects of burnout as the effects of long-term work-related stress. The purpose of the study was to investigate electrophysiological correlates of burnout to explain the mechanisms of the core burnout symptoms: exhaustion and depersonalization/cynicism. The analyzed error-related electrophysiological markers shed light on impaired cognitive mechanisms and the specific changes in information-processing in burnout. In the EEG study design (N = 80), two components of error-related potential (ERP), error-related negativity (ERN), and error positivity (Pe), were analyzed. In the non-clinical burnout group (N = 40), a significant increase in ERN amplitude and a decrease in Pe amplitude were observed compared to controls (N = 40). Enhanced error detection, indexed by increased ERN amplitude, and diminished response monitoring, indexed by decreased Pe amplitude, reveal emerging cognitive problems in the non-clinical burnout group. Cognitive impairments in burnout subjects relate to both reactive and unconscious (ERN) and proactive and conscious (Pe) aspects of error processing. The results indicate a stronger 'reactive control mode' that can deplete resources for proactive control and the ability to actively maintain goals. The analysis refers to error processing and specific task demands, thus should not be extended to cognitive processes in general. The characteristics of ERP patterns in burnout resemble psychophysiological indexes of anxiety (increased ERN) and depressive symptoms (decreased Pe), showing to some extent an overlapping effect of burnout and related symptoms and disorders. The results support the scarce existing data on the psychobiological nature of burnout, while extending and specifying its cognitive characteristics.

  1. Cognitive Impairments in Occupational Burnout – Error Processing and Its Indices of Reactive and Proactive Control

    PubMed Central

    Golonka, Krystyna; Mojsa-Kaja, Justyna; Gawlowska, Magda; Popiel, Katarzyna

    2017-01-01

    The presented study refers to cognitive aspects of burnout as the effects of long-term work-related stress. The purpose of the study was to investigate electrophysiological correlates of burnout to explain the mechanisms of the core burnout symptoms: exhaustion and depersonalization/cynicism. The analyzed error-related electrophysiological markers shed light on impaired cognitive mechanisms and the specific changes in information-processing in burnout. In the EEG study design (N = 80), two components of error-related potential (ERP), error-related negativity (ERN), and error positivity (Pe), were analyzed. In the non-clinical burnout group (N = 40), a significant increase in ERN amplitude and a decrease in Pe amplitude were observed compared to controls (N = 40). Enhanced error detection, indexed by increased ERN amplitude, and diminished response monitoring, indexed by decreased Pe amplitude, reveal emerging cognitive problems in the non-clinical burnout group. Cognitive impairments in burnout subjects relate to both reactive and unconscious (ERN) and proactive and conscious (Pe) aspects of error processing. The results indicate a stronger ‘reactive control mode’ that can deplete resources for proactive control and the ability to actively maintain goals. The analysis refers to error processing and specific task demands, thus should not be extended to cognitive processes in general. The characteristics of ERP patterns in burnout resemble psychophysiological indexes of anxiety (increased ERN) and depressive symptoms (decreased Pe), showing to some extent an overlapping effect of burnout and related symptoms and disorders. The results support the scarce existing data on the psychobiological nature of burnout, while extending and specifying its cognitive characteristics. PMID:28507528

  2. The Influence on Stability Robustness of Compromising on the Zero Tracking Error Requirement in Repetitive Control

    NASA Astrophysics Data System (ADS)

    Shi, Yunde; Longman, Richard W.

    2012-06-01

    Repetitive control (RC) can be used to design active vibration isolation mounts that aim to cancel the influence of spacecraft vibrations on fine pointing equipment. It can cancel the influence of slight imbalance in momentum wheels, reaction wheels, and CMGs. Because RC aims for zero error, it requires reasonably accurate knowledge of the system dynamics all the way to Nyquist frequency. As a result, special methods are needed to establish robustness to model error. A series of publications have demonstrated a method of averaging a cost function over models to increase the robustness. A previous paper improves on this by adjusting the learning rate as a function of frequency to further improve robustness, but there is still a hard limit on phase error. This paper considers yet one more approach, and all three can be used simultaneously. Here we compromise on the zero tracking error requirement for frequencies that require extra robustness. This allows one to extend this hard limit making RC tolerate larger model errors. A quadratic cost is used that penalizes not just the rate of change of the input function, but also the size of the input function. We first establish how to do this for the sister field of iterative learning control, and then the frequency response characteristics are produced for design of repetitive control. The method can improve tracking error for a frequency interval above the frequency at which one would otherwise have to cut off the learning because of model error. Model uncertainty can be used directly in the design process to produce stable RC laws for any level of uncertainty. The design approach differs from typical earlier work that used a sharp frequency cutoff, and instead uses a minimal amount of attenuation needed to produce stability.

  3. Class A/AB second-generation current conveyor with controlled current gain

    NASA Astrophysics Data System (ADS)

    Fabre, A.; Mimeche, N.

    1994-08-01

    A new second-generation current conveyor whose current transfer from X to Z is controlled by a current, is introduced. It functions in class A/AB and uses a mixed translinear loop and two complementary current mirrors with controlled gain. SPICE simulation results, are given. They underline the high potential of the circuit.

  4. Inborn Errors of Metabolism and Epilepsy: Current Understanding, Diagnosis, and Treatment Approaches

    PubMed Central

    Sharma, Suvasini; Prasad, Asuri N.

    2017-01-01

    Inborn errors of metabolism (IEM) are a rare cause of epilepsy, but seizures and epilepsy are frequently encountered in patients with IEM. Since these disorders are related to inherited enzyme deficiencies with resulting effects on metabolic/biochemical pathways, the term “metabolic epilepsy” can be used to include these conditions. These epilepsies can present across the life span, and share features of refractoriness to anti-epileptic drugs, and are often associated with co-morbid developmental delay/regression, intellectual, and behavioral impairments. Some of these disorders are amenable to specific treatment interventions; hence timely and appropriate diagnosis is critical to improve outcomes. In this review, we discuss those disorders in which epilepsy is a dominant feature and present an approach to the clinical recognition, diagnosis, and management of these disorders, with a greater focus on primarily treatable conditions. Finally, we propose a tiered approach that will permit a clinician to systematically investigate, identify, and treat these rare disorders. PMID:28671587

  5. Investigations of stability and dynamic performances of switching regulators employing current-injected control

    NASA Technical Reports Server (NTRS)

    Lee, F. C.; Carter, R. A.

    1981-01-01

    The stability and dynamic performances of a buck/boost regulator employing a current-injected control are examined. Small-signal models for the power state, the multi-loop error processor and the duty-cycle pulse-modulator are developed. The error-processor model which incorporates the current-injected loop, the dc loop and the compensation network permits evaluation of the effects of each individual control loop and their combined efforts toward shaping the performance characteristics of the closed-loop system. Comparisons are made between this modeling approach and earlier approaches. Some important yet subtle dissimilarities are discussed. This model predicts the constant-frequency 50 percent duty-cycle instability which is inherent to the current-injected control.

  6. Design methodology accounting for fabrication errors in manufactured modified Fresnel lenses for controlled LED illumination.

    PubMed

    Shim, Jongmyeong; Kim, Joongeok; Lee, Jinhyung; Park, Changsu; Cho, Eikhyun; Kang, Shinill

    2015-07-27

    The increasing demand for lightweight, miniaturized electronic devices has prompted the development of small, high-performance optical components for light-emitting diode (LED) illumination. As such, the Fresnel lens is widely used in applications due to its compact configuration. However, the vertical groove angle between the optical axis and the groove inner facets in a conventional Fresnel lens creates an inherent Fresnel loss, which degrades optical performance. Modified Fresnel lenses (MFLs) have been proposed in which the groove angles along the optical paths are carefully controlled; however, in practice, the optical performance of MFLs is inferior to the theoretical performance due to fabrication errors, as conventional design methods do not account for fabrication errors as part of the design process. In this study, the Fresnel loss and the loss area due to microscopic fabrication errors in the MFL were theoretically derived to determine optical performance. Based on this analysis, a design method for the MFL accounting for the fabrication errors was proposed. MFLs were fabricated using an ultraviolet imprinting process and an injection molding process, two representative processes with differing fabrication errors. The MFL fabrication error associated with each process was examined analytically and experimentally to investigate our methodology.

  7. Improvement of the grid-connect current quality using novel proportional-integral controller for photovoltaic inverters.

    PubMed

    Cheng, Yuhua; Chen, Kai; Bai, Libing; Yang, Jing

    2014-02-01

    Precise control of the grid-connected current is a challenge in photovoltaic inverter research. Traditional Proportional-Integral (PI) control technology cannot eliminate steady-state error when tracking the sinusoidal signal from the grid, which results in a very high total harmonic distortion in the grid-connected current. A novel PI controller has been developed in this paper, in which the sinusoidal wave is discretized into an N-step input signal that is decided by the control frequency to eliminate the steady state error of the system. The effect of periodical error caused by the dead zone of the power switch and conduction voltage drop can be avoided; the current tracking accuracy and current harmonic content can also be improved. Based on the proposed PI controller, a 700 W photovoltaic grid-connected inverter is developed and validated. The improvement has been demonstrated through experimental results.

  8. A synchronous generator stabilizer design using neuro inverse controller and error reduction network

    SciTech Connect

    Park, Y.M.; Hyun, S.H.; Lee, J.H.

    1996-11-01

    A neuro power system stabilizer (PSS) is developed for multimachine power systems. Each machine is identified in its inverse relation by an artificial neural network named Inverse Dynamics Neural Network (IDNN) off line, which is used as a local inverse controller. The control error due to the interactions between generators is predicted and compensated through another network called Error Reduction Network (ERN). The ERN consists of several IDNNs in the linear combination form. In most neuro controllers, two neural nets are required, one for system emulation, the other for control. In the proposed controller, the only network requiring training is the IDNN. Simulations are performed on two typical cases: an unstable single machine power system of non-minimum phase, and a multimachine power system.

  9. EVALUATION OF CONSTANT CURRENT WELD CONTROL FOR PINCH WELDING

    SciTech Connect

    Korinko, P; STANLEY, S; HOWARD, H

    2005-10-11

    Modern weld controllers typically use current to control the weld process. SRS uses a legacy voltage control method. This task was undertaken to determine if the improvements in the weld control equipment could be implemented to provide improvements to the process control. The constant current mode of operation will reduce weld variability by about a factor of 4. The constant voltage welds were slightly hotter than the constant current welds of the same nominal current. The control mode did not appear to adversely affect the weld quality, but appropriate current ranges need to be established and a qualification methodology for both welding and shunt calibrations needs to be developed and documented.

  10. A parallel row-based algorithm with error control for standard-cell replacement on a hypercube multiprocessor

    NASA Technical Reports Server (NTRS)

    Sargent, Jeff Scott

    1988-01-01

    A new row-based parallel algorithm for standard-cell placement targeted for execution on a hypercube multiprocessor is presented. Key features of this implementation include a dynamic simulated-annealing schedule, row-partitioning of the VLSI chip image, and two novel new approaches to controlling error in parallel cell-placement algorithms; Heuristic Cell-Coloring and Adaptive (Parallel Move) Sequence Control. Heuristic Cell-Coloring identifies sets of noninteracting cells that can be moved repeatedly, and in parallel, with no buildup of error in the placement cost. Adaptive Sequence Control allows multiple parallel cell moves to take place between global cell-position updates. This feedback mechanism is based on an error bound derived analytically from the traditional annealing move-acceptance profile. Placement results are presented for real industry circuits and the performance is summarized of an implementation on the Intel iPSC/2 Hypercube. The runtime of this algorithm is 5 to 16 times faster than a previous program developed for the Hypercube, while producing equivalent quality placement. An integrated place and route program for the Intel iPSC/2 Hypercube is currently being developed.

  11. Quantization-Based Adaptive Actor-Critic Tracking Control With Tracking Error Constraints.

    PubMed

    Fan, Quan-Yong; Yang, Guang-Hong; Ye, Dan

    2017-02-01

    In this paper, the problem of adaptive actor-critic (AC) tracking control is investigated for a class of continuous-time nonlinear systems with unknown nonlinearities and quantized inputs. Different from the existing results based on reinforcement learning, the tracking error constraints are considered and new critic functions are constructed to improve the performance further. To ensure that the tracking errors keep within the predefined time-varying boundaries, a tracking error transformation technique is used to constitute an augmented error system. Specific critic functions, rather than the long-term cost function, are introduced to supervise the tracking performance and tune the weights of the AC neural networks (NNs). A novel adaptive controller with a special structure is designed to reduce the effect of the NN reconstruction errors, input quantization, and disturbances. Based on the Lyapunov stability theory, the boundedness of the closed-loop signals and the desired tracking performance can be guaranteed. Finally, simulations on two connected inverted pendulums are given to illustrate the effectiveness of the proposed method.

  12. Relative and Absolute Error Control in a Finite-Difference Method Solution of Poisson's Equation

    ERIC Educational Resources Information Center

    Prentice, J. S. C.

    2012-01-01

    An algorithm for error control (absolute and relative) in the five-point finite-difference method applied to Poisson's equation is described. The algorithm is based on discretization of the domain of the problem by means of three rectilinear grids, each of different resolution. We discuss some hardware limitations associated with the algorithm,…

  13. 76 FR 67315 - Supplemental Nutrition Assistance Program: Quality Control Error Tolerance Threshold

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-01

    ... / Tuesday, November 1, 2011 / Rules and Regulations#0;#0; ] DEPARTMENT OF AGRICULTURE Food and Nutrition Service 7 CFR Part 275 RIN 0584-AE24 Supplemental Nutrition Assistance Program: Quality Control Error Tolerance Threshold AGENCY: Food and Nutrition Service, USDA. ACTION: Direct final rule. SUMMARY: This...

  14. Two hybrid ARQ error control schemes for near earth satellite communications

    NASA Astrophysics Data System (ADS)

    Lin, Shu; Kasami, Tadao

    1986-12-01

    Two hybrid automatic repeat request (ARQ) error control schemes are proposed for NASA near earth satellite communications. Both schemes are adaptive in nature, and employ cascaded codes to achieve both high reliability and throughput efficiency for high data rate file transfer.

  15. Two hybrid ARQ error control schemes for near Earth satellite communications

    NASA Astrophysics Data System (ADS)

    Lin, S.

    1986-08-01

    Two hybrid Automatic Repeat Request (ARQ) error control schemes are proposed for NASA near Earth satellite communications. Both schemes are adaptive in nature, and employ cascaded codes to achieve both high reliability and throughput efficiency for high data rate file transfer.

  16. Relative and Absolute Error Control in a Finite-Difference Method Solution of Poisson's Equation

    ERIC Educational Resources Information Center

    Prentice, J. S. C.

    2012-01-01

    An algorithm for error control (absolute and relative) in the five-point finite-difference method applied to Poisson's equation is described. The algorithm is based on discretization of the domain of the problem by means of three rectilinear grids, each of different resolution. We discuss some hardware limitations associated with the algorithm,…

  17. Controlling Rater Stringency Error in Clinical Performance Rating: Further Validation of a Performance Rating Theory.

    ERIC Educational Resources Information Center

    Cason, Gerald J.; And Others

    Prior research in a single clinical training setting has shown Cason and Cason's (1981) simplified model of their performance rating theory can improve rating reliability and validity through statistical control of rater stringency error. Here, the model was applied to clinical performance ratings of 14 cohorts (about 250 students and 200 raters)…

  18. Two hybrid ARQ error control schemes for near earth satellite communications

    NASA Technical Reports Server (NTRS)

    Lin, Shu; Kasami, Tadao

    1986-01-01

    Two hybrid automatic repeat request (ARQ) error control schemes are proposed for NASA near earth satellite communications. Both schemes are adaptive in nature, and employ cascaded codes to achieve both high reliability and throughput efficiency for high data rate file transfer.

  19. Two hybrid ARQ error control schemes for near Earth satellite communications

    NASA Technical Reports Server (NTRS)

    Lin, S.

    1986-01-01

    Two hybrid Automatic Repeat Request (ARQ) error control schemes are proposed for NASA near Earth satellite communications. Both schemes are adaptive in nature, and employ cascaded codes to achieve both high reliability and throughput efficiency for high data rate file transfer.

  20. Procedural errors in air traffic control: effects of traffic density, expertise, and automation.

    PubMed

    Di Nocera, Francesco; Fabrizi, Roberto; Terenzi, Michela; Ferlazzo, Fabio

    2006-06-01

    Air traffic management requires operators to frequently shift between multiple tasks and/or goals with different levels of accomplishment. Procedural errors can occur when a controller accomplishes one of the tasks before the entire operation has been completed. The present study had two goals: first, to verify the occurrence of post-completion errors in air traffic control (ATC) tasks; and second, to assess effects on performance of medium term conflict detection (MTCD) tools. There were 18 military controllers who performed a simulated ATC task with and without automation support (MTCD vs. manual) in high and low air traffic density conditions. During the task, which consisted of managing several simulated flights in an enroute ATC scenario, a trace suddenly disappeared "after" the operator took the aircraft in charge, "during" the management of the trace, or "before" the pilot's first contact. In the manual condition, only the fault type "during" was found to be significantly different from the other two. On the contrary, when in the MTCD condition, the fault type "after" generated significantly less errors than the fault type "before." Additionally, automation was found to affect performance of junior controllers, whereas seniors' performance was not affected. Procedural errors can happen in ATC, but automation can mitigate this effect. Lack of benefits for the "before" fault type may be due to the fact that operators extend their reliance to a part of the task that is unsupported by the automated system.

  1. Direct Adaptive Control Methodologies for Flexible-Joint Space Manipulators with Uncertainties and Modeling Errors

    NASA Astrophysics Data System (ADS)

    Ulrich, Steve

    This work addresses the direct adaptive trajectory tracking control problem associated with lightweight space robotic manipulators that exhibit elastic vibrations in their joints, and which are subject to parametric uncertainties and modeling errors. Unlike existing adaptive control methodologies, the proposed flexible-joint control techniques do not require identification of unknown parameters, or mathematical models of the system to be controlled. The direct adaptive controllers developed in this work are based on the model reference adaptive control approach, and manage modeling errors and parametric uncertainties by time-varying the controller gains using new adaptation mechanisms, thereby reducing the errors between an ideal model and the actual robot system. More specifically, new decentralized adaptation mechanisms derived from the simple adaptive control technique and fuzzy logic control theory are considered in this work. Numerical simulations compare the performance of the adaptive controllers with a nonadaptive and a conventional model-based controller, in the context of 12.6 m xx 12.6 m square trajectory tracking. To validate the robustness of the controllers to modeling errors, a new dynamics formulation that includes several nonlinear effects usually neglected in flexible-joint dynamics models is proposed. Results obtained with the adaptive methodologies demonstrate an increased robustness to both uncertainties in joint stiffness coefficients and dynamics modeling errors, as well as highly improved tracking performance compared with the nonadaptive and model-based strategies. Finally, this work considers the partial state feedback problem related to flexible-joint space robotic manipulators equipped only with sensors that provide noisy measurements of motor positions and velocities. An extended Kalman filter-based estimation strategy is developed to estimate all state variables in real-time. The state estimation filter is combined with an adaptive

  2. Control of noisy quantum systems: Field-theory approach to error mitigation

    NASA Astrophysics Data System (ADS)

    Hipolito, Rafael; Goldbart, Paul M.

    2016-04-01

    We consider the basic quantum-control task of obtaining a target unitary operation (i.e., a quantum gate) via control fields that couple to the quantum system and are chosen to best mitigate errors resulting from time-dependent noise, which frustrate this task. We allow for two sources of noise: fluctuations in the control fields and fluctuations arising from the environment. We address the issue of control-error mitigation by means of a formulation rooted in the Martin-Siggia-Rose (MSR) approach to noisy, classical statistical-mechanical systems. To do this, we express the noisy control problem in terms of a path integral, and integrate out the noise to arrive at an effective, noise-free description. We characterize the degree of success in error mitigation via a fidelity metric, which characterizes the proximity of the sought-after evolution to ones that are achievable in the presence of noise. Error mitigation is then best accomplished by applying the optimal control fields, i.e., those that maximize the fidelity subject to any constraints obeyed by the control fields. To make connection with MSR, we reformulate the fidelity in terms of a Schwinger-Keldysh (SK) path integral, with the added twist that the "forward" and "backward" branches of the time contour are inequivalent with respect to the noise. The present approach naturally and readily allows the incorporation of constraints on the control fields—a useful feature in practice, given that constraints feature in all real experiments. In addition to addressing the noise average of the fidelity, we consider its full probability distribution. The information content present in this distribution allows one to address more complex questions regarding error mitigation, including, in principle, questions of extreme value statistics, i.e., the likelihood and impact of rare instances of the fidelity and how to harness or cope with their influence. We illustrate this MSR-SK reformulation by considering a model

  3. Phantom Effects in School Composition Research: Consequences of Failure to Control Biases Due to Measurement Error in Traditional Multilevel Models

    ERIC Educational Resources Information Center

    Televantou, Ioulia; Marsh, Herbert W.; Kyriakides, Leonidas; Nagengast, Benjamin; Fletcher, John; Malmberg, Lars-Erik

    2015-01-01

    The main objective of this study was to quantify the impact of failing to account for measurement error on school compositional effects. Multilevel structural equation models were incorporated to control for measurement error and/or sampling error. Study 1, a large sample of English primary students in Years 1 and 4, revealed a significantly…

  4. Phantom Effects in School Composition Research: Consequences of Failure to Control Biases Due to Measurement Error in Traditional Multilevel Models

    ERIC Educational Resources Information Center

    Televantou, Ioulia; Marsh, Herbert W.; Kyriakides, Leonidas; Nagengast, Benjamin; Fletcher, John; Malmberg, Lars-Erik

    2015-01-01

    The main objective of this study was to quantify the impact of failing to account for measurement error on school compositional effects. Multilevel structural equation models were incorporated to control for measurement error and/or sampling error. Study 1, a large sample of English primary students in Years 1 and 4, revealed a significantly…

  5. 90-deg splicing error control in polarization maintaining fiber resonator based on white-light interferometry

    NASA Astrophysics Data System (ADS)

    Lin, Huizu; Yao, Qiong; Hu, Yongming; Ma, Lina

    2012-05-01

    Polarization fluctuation in polarization maintaining fiber (PMF) resonator is one of the major noise sources in resonant fiber optic gyroscope (R-FOG). 90-deg polarization-axis rotated splicing in R-FOG is an effective way to suppress the polarization-fluctuation induced noise. 90-deg polarization-axis rotated splicing error influences the noise suppression effect. Here, a polarization-coupling testing system based on white-light interferometry is designed to control 90-deg splicing error in double-coupler PMF resonator first time and a result of 0.37-deg splicing error is obtained for the first time. Then the resonant characteristics of the double-coupler PMF resonator are tested using the saw-tooth waveform scanning method. The finesse of this double-coupler PMF resonator is 24.0 and the phase interval of the two eigenstates of polarization (ESOPs) is π.

  6. Correlations of control variables for horizontal background error covariance modeling on cubed-sphere grid

    NASA Astrophysics Data System (ADS)

    Kwun, Jihye; Song, Hyo-Jong; Park, Jong-Im

    2013-04-01

    Background error covariance matrix is very important for variational data assimilation system, determining how the information from observed variables is spread to unobserved variables and spatial points. The full representation of the matrix is impossible because of the huge size so the matrix is constructed implicitly by means of a variable transformation. It is assumed that the forecast errors in the control variables chosen are statistically independent. We used the cubed-sphere geometry based on the spectral element method which is better for parallel application. In cubed-sphere grids, the grid points are located at Gauss-Legendre-Lobatto points on each local element of 6 faces on the sphere. The two stages of the transformation were used in this study. The first is the variable transformation from model to a set of control variables whose errors are assumed to be uncorrelated, which was developed on the cubed sphere-using Galerkin method. Winds are decomposed into rotational part and divergent part by introducing stream function and velocity potential as control variables. The dynamical constraint for balance between mass and wind were made by applying linear balance operator. The second is spectral transformation which is to remove the remaining spatial correlation. The bases for the spectral transform were generated for the cubed-sphere grid. 6-hr difference fields of shallow water equation (SWE) model run initialized by variational data assimilation system were used to obtain forecast error statistics. In the horizontal background error covariance modeling, the regression analysis of the control variables was performed to define the unbalanced variables as the difference between full and correlated part. Regression coefficient was used to remove the remaining correlations between variables.

  7. Multivariable current control for electrically and magnetically coupled superconducting magnets. Revision 1

    SciTech Connect

    Owen, E.W.; Shimer, D.W.

    1985-02-08

    Superconducting magnet systems under construction and projected for the future contain magnets that are magnetically coupled and electrically connected with shared power supplies. A change in one power supply voltage affects all of the magnet currents. A current controller for these system must be designed as a multivariable system. The power describes a method, based on decoupling control, for the rational design of these systems. Dynamic decoupling is achieved by cross-feedback of the measured currents. A network of gains at the input decouples the system statically and eliminates the steady-state error. Errors are then due to component variations. The method has been applied to the magnet system of the MFTF-B, at the Lawrence Livermore National Laboratory.

  8. Improved read disturb and write error rates in voltage-control spintronics memory (VoCSM) by controlling energy barrier height

    NASA Astrophysics Data System (ADS)

    Inokuchi, T.; Yoda, H.; Kato, Y.; Shimizu, M.; Shirotori, S.; Shimomura, N.; Koi, K.; Kamiguchi, Y.; Sugiyama, H.; Oikawa, S.; Ikegami, K.; Ishikawa, M.; Altansargai, B.; Tiwari, A.; Ohsawa, Y.; Saito, Y.; Kurobe, A.

    2017-06-01

    A hybrid writing scheme that combines the spin Hall effect and voltage-controlled magnetic-anisotropy effect is investigated in Ta/CoFeB/MgO/CoFeB/Ru/CoFe/IrMn junctions. The write current and control voltage are applied to Ta and CoFeB/MgO/CoFeB junctions, respectively. The critical current density required for switching the magnetization in CoFeB was modulated 3.6-fold by changing the control voltage from -1.0 V to +1.0 V. This modulation of the write current density is explained by the change in the surface anisotropy of the free layer from 1.7 mJ/m2 to 1.6 mJ/m2, which is caused by the electric field applied to the junction. The read disturb rate and write error rate, which are important performance parameters for memory applications, are drastically improved, and no error was detected in 5 × 108 cycles by controlling read and write sequences.

  9. Filtered Reference and Filtered Error Lms Algorithms for Adaptive Feedforward Control

    NASA Astrophysics Data System (ADS)

    Elliott, S. J.

    1998-11-01

    A unified and consistent formulation is developed for both filtered reference and filtered error forms of the instantaneous steepest decent, or LMS, algorithm when used to adapt FIR feedforward controllers. Both algorithms minimise the mean-square value of the same, output, error function. The two algorithms are first formulated for single-input single-output linear plants. It is argued that since the behaviour of the two algorithms is equivalent in the case of slow adaption, the conditions on the accuracy of the plant model for stability should also be the same in both cases. This is expressed as a bound on the unstructured multiplicative uncertainty of the plant. Filtered reference and filtered error algorithms are also derived for multiple-input multiple-output (MIMO) linear systems, although the filtered reference algorithm is found not to have a simple block diagram interpretation. In the MIMO case, the filtered error form of the algorithm can have considerable computational advantages over the filtered reference form. Finally the two algorithms are extended to the case of non-linear plants and/or controllers which are modelled as feedforward neural networks. In the non-linear case the two formulations of the LMS algorithm reduce to two forms of the widely used backpropagation algorithm.

  10. Numerical Experiments in Error Control for Sound Propagation Using a Damping Layer Boundary Treatment

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    2017-01-01

    This paper presents results from numerical experiments for controlling the error caused by a damping layer boundary treatment when simulating the propagation of an acoustic signal from a continuous pressure source. The computations are with the 2D Linearized Euler Equations (LEE) for both a uniform mean flow and a steady parallel jet. The numerical experiments are with algorithms that are third, fifth, seventh and ninth order accurate in space and time. The numerical domain is enclosed in a damping layer boundary treatment. The damping is implemented in a time accurate manner, with simple polynomial damping profiles of second, fourth, sixth and eighth power. At the outer boundaries of the damping layer the propagating solution is uniformly set to zero. The complete boundary treatment is remarkably simple and intrinsically independant from the dimension of the spatial domain. The reported results show the relative effect on the error from the boundary treatment by varying the damping layer width, damping profile power, damping amplitude, propagtion time, grid resolution and algorithm order. The issue that is being addressed is not the accuracy of the numerical solution when compared to a mathematical solution, but the effect of the complete boundary treatment on the numerical solution, and to what degree the error in the numerical solution from the complete boundary treatment can be controlled. We report maximum relative absolute errors from just the boundary treatment that range from O[10-2] to O[10-7].

  11. Displacement sensor with controlled measuring force and its error analysis and precision verification

    NASA Astrophysics Data System (ADS)

    Yang, Liangen; Wang, Xuanze; Lv, Wei

    2010-12-01

    A displacement sensor with controlled measuring force and its error analysis and precision verification are discussed in this paper. The displacement sensor consists of an electric induction transducer with high resolution and a voice coil motor (VCM). The measuring principles, structure, method enlarging measuring range, signal process of the sensor are discussed. The main error sources such as parallelism error and incline of framework by unequal length of leaf springs, rigidity of measuring rods, shape error of stylus, friction between iron core and other parts, damping of leaf springs, variation of voltage, linearity of induction transducer, resolution and stability are analyzed. A measuring system for surface topography with large measuring range is constructed based on the displacement sensor and 2D moving platform. Measuring precision and stability of the measuring system is verified. Measuring force of the sensor in measurement process of surface topography can be controlled at μN level and hardly changes. It has been used in measurement of bearing ball, bullet mark, etc. It has measuring range up to 2mm and precision of nm level.

  12. Displacement sensor with controlled measuring force and its error analysis and precision verification

    NASA Astrophysics Data System (ADS)

    Yang, Liangen; Wang, Xuanze; Lv, Wei

    2011-05-01

    A displacement sensor with controlled measuring force and its error analysis and precision verification are discussed in this paper. The displacement sensor consists of an electric induction transducer with high resolution and a voice coil motor (VCM). The measuring principles, structure, method enlarging measuring range, signal process of the sensor are discussed. The main error sources such as parallelism error and incline of framework by unequal length of leaf springs, rigidity of measuring rods, shape error of stylus, friction between iron core and other parts, damping of leaf springs, variation of voltage, linearity of induction transducer, resolution and stability are analyzed. A measuring system for surface topography with large measuring range is constructed based on the displacement sensor and 2D moving platform. Measuring precision and stability of the measuring system is verified. Measuring force of the sensor in measurement process of surface topography can be controlled at μN level and hardly changes. It has been used in measurement of bearing ball, bullet mark, etc. It has measuring range up to 2mm and precision of nm level.

  13. Pain control following inguinal herniorrhaphy: current perspectives

    PubMed Central

    Bjurstrom, Martin F; Nicol, Andrea L; Amid, Parviz K; Chen, David C

    2014-01-01

    Inguinal hernia repair is one of the most common surgeries performed worldwide. With the success of modern hernia repair techniques, recurrence rates have significantly declined, with a lower incidence than the development of chronic postherniorrhaphy inguinal pain (CPIP). The avoidance of CPIP is arguably the most important clinical outcome and has the greatest impact on patient satisfaction, health care utilization, societal cost, and quality of life. The etiology of CPIP is multifactorial, with overlapping neuropathic and nociceptive components contributing to this complex syndrome. Treatment is often challenging, and no definitive treatment algorithm exists. Multidisciplinary management of this complex problem improves outcomes, as treatment must be individualized. Current medical, pharmacologic, interventional, and surgical management strategies are reviewed. PMID:24920934

  14. A Criterion to Control Nonlinear Error in the Mixed-Mode Bending Test

    NASA Technical Reports Server (NTRS)

    Reeder, James R.

    2002-01-01

    The mixed-mode bending test ha: been widely used to measure delamination toughness and was recently standardized by ASTM as Standard Test Method D6671-01. This simple test is a combination of the standard Mode I (opening) test and a Mode II (sliding) test. This test uses a unidirectional composite test specimen with an artificial delamination subjected to bending loads to characterize when a delamination will extend. When the displacements become large, the linear theory used to analyze the results of the test yields errors in the calcu1ated toughness values. The current standard places no limit on the specimen loading and therefore test data can be created using the standard that are significantly in error. A method of limiting the error that can be incurred in the calculated toughness values is needed. In this paper, nonlinear models of the MMB test are refined. One of the nonlinear models is then used to develop a simple criterion for prescribing conditions where thc nonlinear error will remain below 5%.

  15. The significance of error dynamics in model-following for flight control design

    NASA Technical Reports Server (NTRS)

    Schmidt, David K.; Anderson, Mark R.

    1987-01-01

    The role of the system error dynamics in model-following control systems is discussed, along with the use of handling quality specifications, actuation bandwidth constraints, stability, and closed-loop performance requirements in flight control design. The model-following problem is formulated using both direct state-space and linear, quadratic, optimization techniques. The results are then demonstrated using several examples involving a generic forward-swept-wing vehicle and a conventional flight vehicle with large parameter uncertainty in order to illustrate the trade-off in closed-loop performance and control law complexity.

  16. 49 CFR 192.473 - External corrosion control: Interference currents.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false External corrosion control: Interference currents. 192.473 Section 192.473 Transportation Other Regulations Relating to Transportation (Continued... for Corrosion Control § 192.473 External corrosion control: Interference currents. (a) Each...

  17. 49 CFR 192.473 - External corrosion control: Interference currents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false External corrosion control: Interference currents. 192.473 Section 192.473 Transportation Other Regulations Relating to Transportation (Continued... for Corrosion Control § 192.473 External corrosion control: Interference currents. (a) Each...

  18. 49 CFR 192.473 - External corrosion control: Interference currents.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false External corrosion control: Interference currents. 192.473 Section 192.473 Transportation Other Regulations Relating to Transportation (Continued... for Corrosion Control § 192.473 External corrosion control: Interference currents. (a) Each operator...

  19. 49 CFR 192.473 - External corrosion control: Interference currents.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false External corrosion control: Interference currents. 192.473 Section 192.473 Transportation Other Regulations Relating to Transportation (Continued... for Corrosion Control § 192.473 External corrosion control: Interference currents. (a) Each operator...

  20. 49 CFR 192.473 - External corrosion control: Interference currents.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false External corrosion control: Interference currents. 192.473 Section 192.473 Transportation Other Regulations Relating to Transportation (Continued... for Corrosion Control § 192.473 External corrosion control: Interference currents. (a) Each operator...

  1. Emission current control system for multiple hollow cathode devices

    NASA Technical Reports Server (NTRS)

    Beattie, John R. (Inventor); Hancock, Donald J. (Inventor)

    1988-01-01

    An emission current control system for balancing the individual emission currents from an array of hollow cathodes has current sensors for determining the current drawn by each cathode from a power supply. Each current sensor has an output signal which has a magnitude proportional to the current. The current sensor output signals are averaged, the average value so obtained being applied to a respective controller for controlling the flow of an ion source material through each cathode. Also applied to each controller are the respective sensor output signals for each cathode and a common reference signal. The flow of source material through each hollow cathode is thereby made proportional to the current drawn by that cathode, the average current drawn by all of the cathodes, and the reference signal. Thus, the emission current of each cathode is controlled such that each is made substantially equal to the emission current of each of the other cathodes. When utilized as a component of a multiple hollow cathode ion propulsion motor, the emission current control system of the invention provides for balancing the thrust of the motor about the thrust axis and also for preventing premature failure of a hollow cathode source due to operation above a maximum rated emission current.

  2. Current status of aggressive blood pressure control

    PubMed Central

    Chrysant, Steven G

    2011-01-01

    The concept of treatment of hypertension has gone through wide swings over the years. From ignoring blood pressure (BP) treatment initially, to aggressive BP control recently. As newer and more effective drugs were developed, it was possible to lower BP to very low levels. However, recent studies have shown that aggressive BP control might not be in the best interest of the patient. Low levels of diastolic BP (DBP) have been associated with increased cardiovascular events, a situation known as the J-curve effect. This has been seen mostly with low DBP, since the coronary arteries are perfused during the diastolic phase of the cardiac cycle. Due to an autoregulatory mechanism, the heart is protected against wide fluctuations of BP. However, the presence of coronary heart disease, hypertension, especially with left ventricular hypertrophy, shift the curve to higher BP levels and makes the heart more liable to DBP fluctuations. The J-Curve effect has been reported by most investigators, but not by others. Recently, a J-Curve effect has been observed with systolic BP (SBP), as well. In contrast to the heart, the brain is very infrequently subjected to J-curve effect, and in contrast to the heart, the brain’s blood flow autoregulation depends mostly on the SBP. A Medline search of the English literature on this subject was conducted between 1992 and 2010 and 11 pertinent articles were selected. These articles with collateral literature will be discussed in this concise review. PMID:21499494

  3. Current status of aggressive blood pressure control.

    PubMed

    Chrysant, Steven G

    2011-03-26

    The concept of treatment of hypertension has gone through wide swings over the years. From ignoring blood pressure (BP) treatment initially, to aggressive BP control recently. As newer and more effective drugs were developed, it was possible to lower BP to very low levels. However, recent studies have shown that aggressive BP control might not be in the best interest of the patient. Low levels of diastolic BP (DBP) have been associated with increased cardiovascular events, a situation known as the J-curve effect. This has been seen mostly with low DBP, since the coronary arteries are perfused during the diastolic phase of the cardiac cycle. Due to an autoregulatory mechanism, the heart is protected against wide fluctuations of BP. However, the presence of coronary heart disease, hypertension, especially with left ventricular hypertrophy, shift the curve to higher BP levels and makes the heart more liable to DBP fluctuations. The J-Curve effect has been reported by most investigators, but not by others. Recently, a J-Curve effect has been observed with systolic BP (SBP), as well. In contrast to the heart, the brain is very infrequently subjected to J-curve effect, and in contrast to the heart, the brain's blood flow autoregulation depends mostly on the SBP. A Medline search of the English literature on this subject was conducted between 1992 and 2010 and 11 pertinent articles were selected. These articles with collateral literature will be discussed in this concise review.

  4. Deploying information technology and continuous control monitoring systems in hospitals to prevent medication errors.

    PubMed

    Escobar-Rodríguez, Tomás; Monge-Lozano, Pedro; Romero-Alonso, Ma Mercedes; Bolívar-Raya, Ma Antonia

    2012-01-01

    The serious repercussions of healthcare errors on patient safety have led hospitals to deploy information technology and continuous control monitoring systems to prevent them. Hospitals are moving away from traditional paper-based systems and focusing on designing new systems that prevent errors, using information technologies to catalyse the process re-engineering. This paper presents a case study that analyses the effect of computerised physician order entry and automated unit-based medication storage and distribution systems on the drug ordering and delivery process. It is concluded that information technology and continuous control monitoring systems have led to significant process re-engineering in the sequential stages of the drug ordering and delivery system. The new systems have also provided the opportunity to improve information available. This is an exploratory case study and the conclusions drawn from it offer possible routes for future research in this field.

  5. Many tests of significance: new methods for controlling type I errors.

    PubMed

    Keselman, H J; Miller, Charles W; Holland, Burt

    2011-12-01

    There have been many discussions of how Type I errors should be controlled when many hypotheses are tested (e.g., all possible comparisons of means, correlations, proportions, the coefficients in hierarchical models, etc.). By and large, researchers have adopted familywise (FWER) control, though this practice certainly is not universal. Familywise control is intended to deal with the multiplicity issue of computing many tests of significance, yet such control is conservative--that is, less powerful--compared to per test/hypothesis control. The purpose of our article is to introduce the readership, particularly those readers familiar with issues related to controlling Type I errors when many tests of significance are computed, to newer methods that provide protection from the effects of multiple testing, yet are more powerful than familywise controlling methods. Specifically, we introduce a number of procedures that control the k-FWER. These methods--say, 2-FWER instead of 1-FWER (i.e., FWER)--are equivalent to specifying that the probability of 2 or more false rejections is controlled at .05, whereas FWER controls the probability of any (i.e., 1 or more) false rejections at .05. 2-FWER implicitly tolerates 1 false rejection and makes no explicit attempt to control the probability of its occurrence, unlike FWER, which tolerates no false rejections at all. More generally, k-FWER tolerates k - 1 false rejections, but controls the probability of k or more false rejections at α =.05. We demonstrate with two published data sets how more hypotheses can be rejected with k-FWER methods compared to FWER control.

  6. Strategies for predictive control of chrome stress-induced registration errors

    NASA Astrophysics Data System (ADS)

    Wei, Alexander C.; Hughes, Gregory P.; Chalekian, Aaron J.; Mackey, Lawrence N.; Mikkelson, Andrew R.; Engelstad, Roxann L.

    2003-06-01

    The focus of this paper is on the development and implementation of a correction strategy that enables mask manufacturers to maintain the yields at current levels while simultaneously reducing registration errors by several nanometers. An alternate consequence is that yields at current registration specifications are improved. Previous work has shown that one source of image placement error is the chrome stress relief caused by etching. This can cause over 25 nm of distortion from the resist pattern to the final etched chrome pattern. Theoretical and experimental data have shown that the distortion has a radial signature, which can be significantly reduced by traditional magnification correction. If the magnitude of this correction term can be predicted before patterning, the magnification can be implemented as a correction term in the writing process, minimizing registration errors. Studies have shown that the percent clear area of the mask, x-field size, y-field size, and chrome stress are the key parameters that will affect the correction term. Data based on finite element simulations were first fit to these parameters to obtain a predictive curve based upon theory. Experimental reticles were then written to test the theoretical prediction. The predictions were found to coincide well with the experimental data; registration improvements of over 20 nm were observed. The correlation was then applied to a set of production reticles. There was an observable improvement in registration after the correlation was implemented, although less than that seen in the experimental reticles.

  7. Study on model current predictive control method of PV grid- connected inverters systems with voltage sag

    NASA Astrophysics Data System (ADS)

    Jin, N.; Yang, F.; Shang, S. Y.; Tao, T.; Liu, J. S.

    2016-08-01

    According to the limitations of the LVRT technology of traditional photovoltaic inverter existed, this paper proposes a low voltage ride through (LVRT) control method based on model current predictive control (MCPC). This method can effectively improve the photovoltaic inverter output characteristics and response speed. The MCPC method of photovoltaic grid-connected inverter designed, the sum of the absolute value of the predictive current and the given current error is adopted as the cost function with the model predictive control method. According to the MCPC, the optimal space voltage vector is selected. Photovoltaic inverter has achieved automatically switches of priority active or reactive power control of two control modes according to the different operating states, which effectively improve the inverter capability of LVRT. The simulation and experimental results proves that the proposed method is correct and effective.

  8. Using Fast-Steering Mirror Control to Reduce Instrument Pointing Errors Caused by Spacecraft Jitter

    NASA Technical Reports Server (NTRS)

    Antol, Jeffery; Holtz, Ted M.; Cuda, Vince; Johnson, Thomas A.

    1996-01-01

    The scope of this study was to investigate the benefit of using feedback control of a Fast Steering Mirror (FSM) to reduce instrument pointing errors. Initially, the study identified FSM control technologies and categorized them according to their use, range of applicability, and physical requirements. Candidate payloads were then evaluated according to their relevance in use of fast steering minor control technologies. This leads to the mission and instrument selection which served as the candidate mission for numerical modeling. A standard SmallSat was designed in order to accommodate the payload requirements (weight, size, power, etc.). This included sizing the SmallSat bus, sizing the solar array, choosing appropriate antennas, and identifying an attitude control system (ACS). A feedback control system for the FSM compensation was then designed, and the instrument pointing error and SmallSat jitter environment for open-loop and closed-loop FSM control were evaluated for typical SmallSat disturbances. The results were then compared to determine the effectiveness of the FSM feedback control system.

  9. Apparatus for electrode current control in linear MHD generators

    DOEpatents

    Demirjian, Ara M.; Solbes, Albert

    1984-01-01

    Apparatus for controlling a plurality of opposing, electrode, direct-currents at pre-set locations across a channel that comprises a converter for converting each electrode current into first and second periodic control signals which are 180.degree. out of phase with respect to each other and which have equal magnitudes corresponding to the magnitude of the associated electrode current; and couplers for magnetically coupling individual ones of the first control signals and for magnetically coupling individual ones of the second signals such that the corresponding electrode currents are equalized or rendered proportional by balancing the same in the same or constant ratios in accordance with the locations of the electrode currents.

  10. Many Phenotypes Without Many False Discoveries: Error Controlling Strategies for Multitrait Association Studies

    PubMed Central

    Peterson, Christine B.; Bogomolov, Marina; Benjamini, Yoav

    2015-01-01

    ABSTRACT The genetic basis of multiple phenotypes such as gene expression, metabolite levels, or imaging features is often investigated by testing a large collection of hypotheses, probing the existence of association between each of the traits and hundreds of thousands of genotyped variants. Appropriate multiplicity adjustment is crucial to guarantee replicability of findings, and the false discovery rate (FDR) is frequently adopted as a measure of global error. In the interest of interpretability, results are often summarized so that reporting focuses on variants discovered to be associated to some phenotypes. We show that applying FDR‐controlling procedures on the entire collection of hypotheses fails to control the rate of false discovery of associated variants as well as the expected value of the average proportion of false discovery of phenotypes influenced by such variants. We propose a simple hierarchical testing procedure that allows control of both these error rates and provides a more reliable basis for the identification of variants with functional effects. We demonstrate the utility of this approach through simulation studies comparing various error rates and measures of power for genetic association studies of multiple traits. Finally, we apply the proposed method to identify genetic variants that impact flowering phenotypes in Arabidopsis thaliana, expanding the set of discoveries. PMID:26626037

  11. Many Phenotypes Without Many False Discoveries: Error Controlling Strategies for Multitrait Association Studies.

    PubMed

    Peterson, Christine B; Bogomolov, Marina; Benjamini, Yoav; Sabatti, Chiara

    2016-01-01

    The genetic basis of multiple phenotypes such as gene expression, metabolite levels, or imaging features is often investigated by testing a large collection of hypotheses, probing the existence of association between each of the traits and hundreds of thousands of genotyped variants. Appropriate multiplicity adjustment is crucial to guarantee replicability of findings, and the false discovery rate (FDR) is frequently adopted as a measure of global error. In the interest of interpretability, results are often summarized so that reporting focuses on variants discovered to be associated to some phenotypes. We show that applying FDR-controlling procedures on the entire collection of hypotheses fails to control the rate of false discovery of associated variants as well as the expected value of the average proportion of false discovery of phenotypes influenced by such variants. We propose a simple hierarchical testing procedure that allows control of both these error rates and provides a more reliable basis for the identification of variants with functional effects. We demonstrate the utility of this approach through simulation studies comparing various error rates and measures of power for genetic association studies of multiple traits. Finally, we apply the proposed method to identify genetic variants that impact flowering phenotypes in Arabidopsis thaliana, expanding the set of discoveries. © 2015 The Authors. *Genetic Epidemiology published by Wiley Periodicals, Inc.

  12. [Comparative study of refractive errors in simple congenital myogenic ptosis and control children].

    PubMed

    Pérez-Iñigo, M A; González, I; Mayoral, F; Ferrer, C; Honrubia, F M

    2008-10-01

    To study refractive errors in children with relatively serious congenital myogenic ptosis and to carry out a comparative study in relation to control children in our population. We included 35 children with simple congenital myogenic ptosis, 27 of them had minor ptosis, 3 moderate ptosis and 5 serious ptosis. Thirty-five children were also in the control group. One eye of every subject was included, the worst eye in subjects of the ptosis group and an eye selected at random in control group subjects. A comparative study of refractive data in every group was carried out, using the Student's t-test, ANOVA and Chi square or Yates correction tests. We obtained significant differences between children with ptosis and controls in average spherical equivalent (3.08/1.49), in average absolute sphere (2.80/1.42) and in average absolute cylinder (0.81/0.31) (p<0.05). We also observed a relation between the presence of astigmatism and the seriousness of ptosis (chi2=6.88>5.99), and between the need for optical correction and the presence of ptosis (chi2=15.92>3.84). Children with simple congenital myogenic ptosis in our enviroment have greater refractive errors than control children. Ptosis children require optical correction more frequently than control. The more serious the ptosis, the more likelihood there is of having astigmatism.

  13. First-principles-driven model-based current profile control for the DIII-D tokamak via LQI optimal control

    NASA Astrophysics Data System (ADS)

    Boyer, Mark D.; Barton, Justin; Schuster, Eugenio; Luce, Tim C.; Ferron, John R.; Walker, Michael L.; Humphreys, David A.; Penaflor, Ben G.; Johnson, Robert D.

    2013-10-01

    In tokamak fusion plasmas, control of the spatial distribution profile of the toroidal plasma current plays an important role in realizing certain advanced operating scenarios. These scenarios, characterized by improved confinement, magnetohydrodynamic stability, and a high fraction of non-inductively driven plasma current, could enable steady-state reactor operation with high fusion gain. Current profile control experiments at the DIII-D tokamak focus on using a combination of feedforward and feedback control to achieve a targeted current profile during the ramp-up and early flat-top phases of the shot and then to actively maintain this profile during the rest of the discharge. The dynamic evolution of the current profile is nonlinearly coupled with several plasma parameters, motivating the design of model-based control algorithms that can exploit knowledge of the system to achieve desired performance. In this work, we use a first-principles-driven, control-oriented model of the current profile evolution in low confinement mode (L-mode) discharges in DIII-D to design a feedback control law for regulating the profile around a desired trajectory. The model combines the magnetic diffusion equations with empirical correlations for the electron temperature, resistivity, and non-inductive current drive. To improve tracking performance of the system, a nonlinear input transformation is combined with a linear-quadratic-integral (LQI) optimal controller designed to minimize a weighted combination of the tracking error and controller effort. The resulting control law utilizes the total plasma current, total external heating power, and line averaged plasma density as actuators. A simulation study was used to test the controller's performance and ensure correct implementation in the DIII-D plasma control system prior to experimental testing. Experimental results are presented that show the first-principles-driven model-based control scheme's successful rejection of input

  14. Estimation of Aperture Errors with Direct Interferometer-Output Feedback for Spacecraft Formation Control

    NASA Technical Reports Server (NTRS)

    Lu, Hui-Ling; Cheng, Victor H. L.; Leitner, Jesse A.; Carpenter, Kenneth G.

    2004-01-01

    Long-baseline space interferometers involving formation flying of multiple spacecraft hold great promise as future space missions for high-resolution imagery. The major challenge of obtaining high-quality interferometric synthesized images from long-baseline space interferometers is to control these spacecraft and their optics payloads in the specified configuration accurately. In this paper, we describe our effort toward fine control of long-baseline space interferometers without resorting to additional sensing equipment. We present an estimation procedure that effectively extracts relative x/y translational exit pupil aperture deviations from the raw interferometric image with small estimation errors.

  15. Improving transient performance of adaptive control architectures using frequency-limited system error dynamics

    NASA Astrophysics Data System (ADS)

    Yucelen, Tansel; De La Torre, Gerardo; Johnson, Eric N.

    2014-11-01

    Although adaptive control theory offers mathematical tools to achieve system performance without excessive reliance on dynamical system models, its applications to safety-critical systems can be limited due to poor transient performance and robustness. In this paper, we develop an adaptive control architecture to achieve stabilisation and command following of uncertain dynamical systems with improved transient performance. Our framework consists of a new reference system and an adaptive controller. The proposed reference system captures a desired closed-loop dynamical system behaviour modified by a mismatch term representing the high-frequency content between the uncertain dynamical system and this reference system, i.e., the system error. In particular, this mismatch term allows the frequency content of the system error dynamics to be limited, which is used to drive the adaptive controller. It is shown that this key feature of our framework yields fast adaptation without incurring high-frequency oscillations in the transient performance. We further show the effects of design parameters on the system performance, analyse closeness of the uncertain dynamical system to the unmodified (ideal) reference system, discuss robustness of the proposed approach with respect to time-varying uncertainties and disturbances, and make connections to gradient minimisation and classical control theory. A numerical example is provided to demonstrate the efficacy of the proposed architecture.

  16. Development and application of a human error identification tool for air traffic control.

    PubMed

    Shorrock, Steven T; Kirwan, Barry

    2002-07-01

    This paper outlines a human error identification (HEI) technique called TRACEr--technique for the retrospective and predictive analysis of cognitive errors in air traffic control (ATC). The paper firstly considers the need for an HEI tool in ATC, and key requirements for the technique are noted. The technique, which comprises a number of inter-related taxonomies, based around a simple cognitive framework, is then described. A study concerning a real-world application of TRACEr is outlined-the evaluation of several options for reduced separation minima in unregulated UK airspace. In this study, TRACEr was used predictively and retrospectively, looking forward to pre-empt potential problems and looking back to learn from experience. The paper concludes that TRACEr is a valuable aid to design, development and operations in UK ATC, and has indeed been used as a basis for further applications in ATC both in Europe and the USA.

  17. Explosive magnetic source of current with controllable output voltage

    NASA Astrophysics Data System (ADS)

    Dudai, P. V.; Zimenkov, A. A.; Ivanov, V. A.; Ivanov, E. I.; Karpov, G. V.; Polyushko, S. M.; Skobelev, A. N.; Fevralev, A. Yu.

    2015-01-01

    The paper describes a small-size explosive current source with controllable output voltage shaping a megaampere current pulse. This energy source comprises a helical explosive magnetic generator and an explosive sectionalized current opening switch and is designed to power gas-discharge chambers of the plasma focus type. Control of the output voltage of the pulsed current source is performed in such a manner that in each of the series-connected sections of the explosive current opening switch, voltage is generated with a given time shift relative to the neighboring section.

  18. Improved Load Compensation using Harmonic Compensator in dq0 Current Controller for DSTATCOM

    NASA Astrophysics Data System (ADS)

    Geddada, Nagesh; Mishra, Mahesh Kumar

    2014-12-01

    This paper presents distribution static compensator (DSTATCOM) with dq0 current controller and sine pulse width modulation (SPWM) switching for compensation of unbalanced nonlinear load in distribution system. DSTATCOM, connected in parallel to load at the point of common coupling (PCC), is used for supplying reactive and harmonic components of load current demand. This dq0 current controller is implemented in synchronous reference frame (SRF) rotating at fundamental frequency and consists of harmonic compensation (HC) regulator along with proportional integrator (PI) regulator. HC regulator is realized by number of sinusoidal signal integrators (SSIs) in parallel. The SSI provides high gain for tuned harmonic frequency and helps in minimizing filter current tracking error while compensating for load harmonic currents. Zero-axis controller, which compensates load neutral current and helps in obtaining balanced utility currents, is provided along with d, q controllers. SPWM switching generates inverter gating pulses at constant frequency, which reduces stress levels on VSI switches and simplifies the design of interface filter. Simulation studies of DSTATCOM load compensation with dq0 current controller are carried out in Matlab/Simulink and experimental verification is done using dSpace 1104 with Matlab real-time interface (RTI).

  19. Fuzzy Current-Mode Control and Stability Analysis

    NASA Technical Reports Server (NTRS)

    Kopasakis, George

    2000-01-01

    In this paper a current-mode control (CMC) methodology is developed for a buck converter by using a fuzzy logic controller. Conventional CMC methodologies are based on lead-lag compensation with voltage and inductor current feedback. In this paper the converter lead-lag compensation will be substituted with a fuzzy controller. A small-signal model of the fuzzy controller will also be developed in order to examine the stability properties of this buck converter control system. The paper develops an analytical approach, introducing fuzzy control into the area of CMC.

  20. How the credit assignment problems in motor control could be solved after the cerebellum predicts increases in error

    PubMed Central

    Verduzco-Flores, Sergio O.; O'Reilly, Randall C.

    2015-01-01

    We present a cerebellar architecture with two main characteristics. The first one is that complex spikes respond to increases in sensory errors. The second one is that cerebellar modules associate particular contexts where errors have increased in the past with corrective commands that stop the increase in error. We analyze our architecture formally and computationally for the case of reaching in a 3D environment. In the case of motor control, we show that there are synergies of this architecture with the Equilibrium-Point hypothesis, leading to novel ways to solve the motor error and distal learning problems. In particular, the presence of desired equilibrium lengths for muscles provides a way to know when the error is increasing, and which corrections to apply. In the context of Threshold Control Theory and Perceptual Control Theory we show how to extend our model so it implements anticipative corrections in cascade control systems that span from muscle contractions to cognitive operations. PMID:25852535

  1. Indirect control of antiferromagnetic domain walls with spin current.

    PubMed

    Wieser, R; Vedmedenko, E Y; Wiesendanger, R

    2011-02-11

    The indirect controlled displacement of an antiferromagnetic domain wall by a spin current is studied by Landau-Lifshitz-Gilbert spin dynamics. The antiferromagnetic domain wall can be shifted both by a spin-polarized tunnel current of a scanning tunneling microscope or by a current driven ferromagnetic domain wall in an exchange coupled antiferromagnetic-ferromagnetic layer system. The indirect control of antiferromagnetic domain walls opens up a new and promising direction for future spin device applications based on antiferromagnetic materials.

  2. Three-dimensional shape optical measurement using constant gap control and error compensation

    SciTech Connect

    Park, Kyihwan; Kim, Sangyoo; Choi, Kyosoon

    2008-03-15

    The optical laser displacement sensor is widely used for noncontact measurement of the three-dimensional (3D) shape profile of the object surface. When the surface of an object has a slope variation, the sensor gain is proportionally varied according to that of the object surface. In order to solve the sensor gain variation problem, the constant gap control method is applied to adjust the gap to the nominal distance. Control error compensation is also proposed to cope with the situation even when the gap is not perfectly controlled to the nominal distance using an additional sensor attached to the actuator. 3D shape measurement applying the proposed constant gap control method shows better performances rather than the constant sensor height method.

  3. Zero-error tracking control of uncertain nonlinear systems in the presence of actuator hysteresis

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengqiang; Shen, Hao; Li, Ze; Zhang, Shuzhen

    2015-11-01

    In this paper, the problem of adaptive tracking control is addressed for a class of nonlinear systems with unknown constant parameters and unknown actuator nonlinearity. The actuator nonlinearity is modelled as the backlash-like hysteresis, which is described by a differential model. The prior knowledge on the control gain sign is not required, and only the assumption on the reference signal is made. By combining the adaptive backstepping technique with the Nussbaum gain approach, an adaptive compensation controller design approach is developed. It is proved that the proposed control approach can guarantee that all the signals in the closed-loop system are bounded, and the tracking error can converge to zero asymptotically despite the presence of the actuator hysteresis. Two simulation examples are included to illustrate the effectiveness of the proposed approach.

  4. Errors in emergency feeds in inherited metabolic disorders: a randomised controlled trial of three preparation methods.

    PubMed

    Gokmen-Ozel, H; Daly, A; Davies, P; Chahal, S; MacDonald, A

    2010-10-01

    Glucose polymer-based emergency feeds (EF), used during illness to prevent metabolic decompensation and encephalopathy in inherited metabolic disorders, should be produced accurately and safely. In a randomised, prospective, controlled study, the aim was to investigate if when preparing age-appropriate EF, a pre-measured sachet of glucose polymer, compared with scoops and weighing (using digital scales), decreased carer errors. 47 carers (3 men, 44 women) of 52 inherited metabolic disorders patients were recruited. The carers made EF using all three techniques (weighing, scoops and pre-measured sachets) under supervision in controlled and home conditions. A 100-ml aliquot of each EF was analysed for carbohydrate concentration. Under controlled preparation conditions, with 1 litre EFs, the % median glucose polymer concentration closest to target amounts was (1) pre-measured sachets (105%), (2) weighing (107%) and (3) scoops (118%; p<0.001). Similarly, under home conditions, the closest method was (1) pre-measured sachets (111%), (2) weighing (112%) and (3) scoops (118%; p<0.05). Under home preparation conditions, with 200 ml EFs, the pre-measured sachets were more likely to be within 20% of target weight than weighing (p<0.05), but there was no difference with scoops. Common errors observed were inaccurate water measurements (40% controlled and home conditions), incorrect scoop measurements and difficulty using digital scales. CONCLUSIONS; Overall, using pre-measured sachets was more accurate in EF production. Pre-measured sachets are likely to decrease preparation error and, therefore, reduce the risk of feed intolerance, particularly osmotic diarrhoea and consequential metabolic decompensation and encephalopathy.

  5. Automatic-controlled information processing and error detection in a simulated pharmacy-verification task.

    PubMed

    Reilly, Sean; Grasha, Anthony F; Matthews, Gerald; Schafer, John

    2003-08-01

    The relationships between attentional variables and information-processing demands of pharmacy dispensing tasks that contribute to difficulties in cognitive performance are not well-known. In the present study, a psychological approach to medical dispensing errors, the cognitive-systems performance model of Grasha, was employed to evaluate the contributions of individual differences in attention and alterations in visual task information on simulated pharmacy-verification performance, perceived workload, and self-reported stress. 73 college-age volunteers completed a pretest battery containing psychological measures of automatic and controlled information processing, and one-week later spent 265 min. completing the end visual-inspection process for 200 simulated prescriptions, 27% of which contained artificially inserted errors. Evidence suggesting that both automatic and controlled processes underlie performance of a simulated pharmacy-verification task was obtained. Individual differences in controlled information processing were mildly predictive of detection accuracy, while contrary to expectations, automatic processing scores did not produce significant relationships. Detection associated with experimental alterations in font size (12-pt. vs 6-pt.) of critical prescription label information was partially in line with expectations from the cognitive-systems performance model, while additional visual enhancements via a magnification/illumination device yielded mixed results. Finally, reports of perceived workload (NASA Task Load Index) and specific patterns of self-reported stress (Dundee Stress State Questionnaire) were consistent with a three-tier behavioral framework offered recently by Matthews, Davies, Westerman, and Stammers for predicting behaviors along the automatic-controlled continuum.

  6. An Adaptive Method of Lines with Error Control for Parabolic Equations of the Reaction-Diffusion Type.

    DTIC Science & Technology

    1984-06-01

    space discretization error . 1. I 3 1. INTRODUCTION Reaction- diffusion processes occur in many branches of biology and physical chemistry. Examples...to model reaction- diffusion phenomena. The primary goal of this adaptive method is to keep a particular norm of the space discretization error less...AD-A142 253 AN ADAPTIVE MET6 OFD LNES WITH ERROR CONTROL FOR 1 INST FOR PHYSICAL SCIENCE AND TECH. I BABUSKAAAO C7 EA OH S UMR AN UNVC EEP R

  7. Over Current Protection for PFM Control DC-DC Converter

    NASA Astrophysics Data System (ADS)

    Yamada, Kouhei; Sugahara, Satoshi; Fujii, Nobuo

    An over current protection method suitable for Fixed ON-time PFM (Pulse Frequency Modulation) Control DC-DC converters is proposed. It is based on inductor bottom current limiting, realized by monitoring the synchronous rectifier current and extending the OFF-phase of the main switch until it decreases to a predetermined limit, and can properly limit the output current even in case of short circuit. A Fixed ON-time PFM DC-DC converter with the proposed over current protection was designed and fabricated in CMOS IC. Its current limiting operation was verified with simulations and measurements.

  8. Cognitive control adjustments in healthy older and younger adults: Conflict adaptation, the error-related negativity (ERN), and evidence of generalized decline with age.

    PubMed

    Larson, Michael J; Clayson, Peter E; Keith, Cierra M; Hunt, Isaac J; Hedges, Dawson W; Nielsen, Brent L; Call, Vaughn R A

    2016-03-01

    Older adults display alterations in neural reflections of conflict-related processing. We examined response times (RTs), error rates, and event-related potential (ERP; N2 and P3 components) indices of conflict adaptation (i.e., congruency sequence effects) a cognitive control process wherein previous-trial congruency influences current-trial performance, along with post-error slowing, correct-related negativity (CRN), error-related negativity (ERN) and error positivity (Pe) amplitudes in 65 healthy older adults and 94 healthy younger adults. Older adults showed generalized slowing, had decreased post-error slowing, and committed more errors than younger adults. Both older and younger adults showed conflict adaptation effects; magnitude of conflict adaptation did not differ by age. N2 amplitudes were similar between groups; younger, but not older, adults showed conflict adaptation effects for P3 component amplitudes. CRN and Pe, but not ERN, amplitudes differed between groups. Data support generalized declines in cognitive control processes in older adults without specific deficits in conflict adaptation.

  9. Quality controls in integrative approaches to detect errors and inconsistencies in biological databases.

    PubMed

    Ghisalberti, Giorgio; Masseroli, Marco; Tettamanti, Luca

    2010-03-25

    Numerous biomolecular data are available, but they are scattered in many databases and only some of them are curated by experts. Most available data are computationally derived and include errors and inconsistencies. Effective use of available data in order to derive new knowledge hence requires data integration and quality improvement. Many approaches for data integration have been proposed. Data warehousing seams to be the most adequate when comprehensive analysis of integrated data is required. This makes it the most suitable also to implement comprehensive quality controls on integrated data. We previously developed GFINDer (http://www.bioinformatics.polimi.it/GFINDer/), a web system that supports scientists in effectively using available information. It allows comprehensive statistical analysis and mining of functional and phenotypic annotations of gene lists, such as those identified by high-throughput biomolecular experiments. GFINDer backend is composed of a multi-organism genomic and proteomic data warehouse (GPDW). Within the GPDW, several controlled terminologies and ontologies, which describe gene and gene product related biomolecular processes, functions and phenotypes, are imported and integrated, together with their associations with genes and proteins of several organisms. In order to ease maintaining updated the GPDW and to ensure the best possible quality of data integrated in subsequent updating of the data warehouse, we developed several automatic procedures. Within them, we implemented numerous data quality control techniques to test the integrated data for a variety of possible errors and inconsistencies. Among other features, the implemented controls check data structure and completeness, ontological data consistency, ID format and evolution, unexpected data quantification values, and consistency of data from single and multiple sources. We use the implemented controls to analyze the quality of data available from several different biological

  10. Detecting errors and anomalies in computerized materials control and accountability databases

    SciTech Connect

    Whiteson, R.; Hench, K.; Yarbro, T.; Baumgart, C.

    1998-12-31

    The Automated MC and A Database Assessment project is aimed at improving anomaly and error detection in materials control and accountability (MC and A) databases and increasing confidence in the data that they contain. Anomalous data resulting in poor categorization of nuclear material inventories greatly reduces the value of the database information to users. Therefore it is essential that MC and A data be assessed periodically for anomalies or errors. Anomaly detection can identify errors in databases and thus provide assurance of the integrity of data. An expert system has been developed at Los Alamos National Laboratory that examines these large databases for anomalous or erroneous data. For several years, MC and A subject matter experts at Los Alamos have been using this automated system to examine the large amounts of accountability data that the Los Alamos Plutonium Facility generates. These data are collected and managed by the Material Accountability and Safeguards System, a near-real-time computerized nuclear material accountability and safeguards system. This year they have expanded the user base, customizing the anomaly detector for the varying requirements of different groups of users. This paper describes the progress in customizing the expert systems to the needs of the users of the data and reports on their results.

  11. Which medical error to disclose to patients and by whom? Public preference and perceptions of norm and current practice.

    PubMed

    Hammami, Muhammad M; Attalah, Sahar; Al Qadire, Mohammad

    2010-10-18

    Disclosure of near miss medical error (ME) and who should disclose ME to patients continue to be controversial. Further, available recommendations on disclosure of ME have emerged largely in Western culture; their suitability to Islamic/Arabic culture is not known. We surveyed 902 individuals attending the outpatient's clinics of a tertiary care hospital in Saudi Arabia. Personal preference and perceptions of norm and current practice regarding which ME to be disclosed (5 options: don't disclose; disclose if associated with major, moderate, or minor harm; disclose near miss) and by whom (6 options: any employee, any physician, at-fault-physician, manager of at-fault-physician, medical director, or chief executive director) were explored. Mean (SD) age of respondents was 33.9 (10) year, 47% were males, 90% Saudis, 37% patients, 49% employed, and 61% with college or higher education. The percentage (95% confidence interval) of respondents who preferred to be informed of harmful ME, of near miss ME, or by at-fault physician were 60.0% (56.8 to 63.2), 35.5% (32.4 to 38.6), and 59.7% (56.5 to 63.0), respectively. Respectively, 68.2% (65.2 to 71.2) and 17.3% (14.7 to 19.8) believed that as currently practiced, harmful ME and near miss ME are disclosed, and 34.0% (30.7 to 37.4) that ME are disclosed by at-fault-physician. Distributions of perception of norm and preference were similar but significantly different from the distribution of perception of current practice (P < 0.001). In a forward stepwise regression analysis, older age, female gender, and being healthy predicted preference of disclosure of near miss ME, while younger age and male gender predicted preference of no-disclosure of ME. Female gender also predicted preferring disclosure by the at-fault-physician. We conclude that: 1) there is a considerable diversity in preferences and perceptions of norm and current practice among respondents regarding which ME to be disclosed and by whom, 2) Distributions of

  12. SEPARABLE RESPONSES TO ERROR, AMBIGUITY, AND REACTION TIME IN CINGULO-OPERCULAR TASK CONTROL REGIONS

    PubMed Central

    Neta, Maital; Schlaggar, Bradley L.; Petersen, Steven E.

    2014-01-01

    The dorsal anterior cingulate (dACC), along with the closely affiliated anterior insula/frontal operculum have been demonstrated to show three types of task control signals across a wide variety of tasks. One of these signals, a transient signal that is thought to represent performance feedback, shows greater activity to error than correct trials. Other work has found similar effects for uncertainty/ambiguity or conflict, though some argue that dACC activity is, instead, modulated primarily by other processes more reflected in reaction time. Here, we demonstrate that, rather than a single explanation, multiple information processing operations are crucial to characterizing the function of these brain regions, by comparing operations within a single paradigm. Participants performed two tasks in an fMRI experimental session: (1) deciding whether or not visually presented word pairs rhyme, and (2) rating auditorily presented single words as abstract or concrete. A pilot was used to identify ambiguous stimuli for both tasks (e.g., word pair: BASS/GRACE; single word: CHANGE). We found greater cingulo-opercular activity for errors and ambiguous trials than clear/correct trials, with a robust effect of reaction time. The effects of error and ambiguity remained when reaction time was regressed out, although the differences decreased. Further stepwise regression of response consensus (agreement across participants for each stimulus; a proxy for ambiguity) decreased differences between ambiguous and clear trials, but left error-related differences almost completely intact. These observations suggest that trial-wise responses in cinguloopercular regions monitor multiple performance indices, including accuracy, ambiguity, and reaction time. PMID:24887509

  13. Separable responses to error, ambiguity, and reaction time in cingulo-opercular task control regions.

    PubMed

    Neta, Maital; Schlaggar, Bradley L; Petersen, Steven E

    2014-10-01

    The dorsal anterior cingulate (dACC), along with the closely affiliated anterior insula/frontal operculum, have been demonstrated to show three types of task control signals across a wide variety of tasks. One of these signals, a transient signal that is thought to represent performance feedback, shows greater activity to error than correct trials. Other work has found similar effects for uncertainty/ambiguity or conflict, though some argue that dACC activity is, instead, modulated primarily by other processes more reflected in reaction time. Here, we demonstrate that, rather than a single explanation, multiple information processing operations are crucial to characterizing the function of these brain regions, by comparing operations within a single paradigm. Participants performed two tasks in an fMRI experimental session: (1) deciding whether or not visually presented word pairs rhyme, and (2) rating auditorily presented single words as abstract or concrete. A pilot was used to identify ambiguous stimuli for both tasks (e.g., word pair: BASS/GRACE; single word: CHANGE). We found greater cingulo-opercular activity for errors and ambiguous trials than clear/correct trials, with a robust effect of reaction time. The effects of error and ambiguity remained when reaction time was regressed out, although the differences decreased. Further stepwise regression of response consensus (agreement across participants for each stimulus; a proxy for ambiguity) decreased differences between ambiguous and clear trials, but left error-related differences almost completely intact. These observations suggest that trial-wise responses in cingulo-opercular regions monitor multiple performance indices, including accuracy, ambiguity, and reaction time.

  14. Dynamic Programming and Error Estimates for Stochastic Control Problems with Maximum Cost

    SciTech Connect

    Bokanowski, Olivier; Picarelli, Athena; Zidani, Hasnaa

    2015-02-15

    This work is concerned with stochastic optimal control for a running maximum cost. A direct approach based on dynamic programming techniques is studied leading to the characterization of the value function as the unique viscosity solution of a second order Hamilton–Jacobi–Bellman (HJB) equation with an oblique derivative boundary condition. A general numerical scheme is proposed and a convergence result is provided. Error estimates are obtained for the semi-Lagrangian scheme. These results can apply to the case of lookback options in finance. Moreover, optimal control problems with maximum cost arise in the characterization of the reachable sets for a system of controlled stochastic differential equations. Some numerical simulations on examples of reachable analysis are included to illustrate our approach.

  15. Adaptive control of nonlinear system using online error minimum neural networks.

    PubMed

    Jia, Chao; Li, Xiaoli; Wang, Kang; Ding, Dawei

    2016-11-01

    In this paper, a new learning algorithm named OEM-ELM (Online Error Minimized-ELM) is proposed based on ELM (Extreme Learning Machine) neural network algorithm and the spreading of its main structure. The core idea of this OEM-ELM algorithm is: online learning, evaluation of network performance, and increasing of the number of hidden nodes. It combines the advantages of OS-ELM and EM-ELM, which can improve the capability of identification and avoid the redundancy of networks. The adaptive control based on the proposed algorithm OEM-ELM is set up which has stronger adaptive capability to the change of environment. The adaptive control of chemical process Continuous Stirred Tank Reactor (CSTR) is also given for application. The simulation results show that the proposed algorithm with respect to the traditional ELM algorithm can avoid network redundancy and improve the control performance greatly.

  16. Control of rolled edge based on the discrete local error figuring technique

    NASA Astrophysics Data System (ADS)

    Du, Hang; Li, Shengyi; Song, Ci

    2016-10-01

    Computer Controlled Optical Surfacing (CCOS) is an important technology for manufacturing optical aspheric mirrors. Edge effect of small tool manufacturing restricts the machining precision and efficiency of CCOS technology. Edge effect is mainly caused by the polish tool cannot move to the very edge of workpiece and the change of pressure distribution when the tool move to the edge of workpiece. This article corrects the rolled edge effect of CCOS by different dimensions of polishing tool combination process and incorporated with the locality residual error trace contour path planning. Provide feasibility for the rolled edge by different dimensions of polishing tool combination process.

  17. Lateral Current Reduction by Voltage Drop Compensator for Multiple Autonomously Controlled UPS Connected in Parallel

    NASA Astrophysics Data System (ADS)

    Sato, Eduardo Kazuhide; Kawamura, Atsuo

    An autonomous control for redundant parallelism of uninterruptible power supplies (UPS) connected in parallel has successfully been proposed and discussed in theoretical and experimental terms. This independent control only requires the measurement of the output current. With the computation of the active and reactive currents, proportional-integral-based controllers provide the phase angle and amplitude, respectively, of the output voltage. However, when voltage difference between UPS exists, there is a flow of reactive lateral current, which makes the load sharing disproportional. A preliminary approach to reduce this circulating current considers a high proportional gain in the control equation for output voltage amplitude in order to reduce the offset error. Nevertheless it implies in high variation of the voltage amplitude, so that voltage levels easily reaches the limit, and the respective control equation becomes incapable to compensate any voltage difference. This paper proposes a compensator to counterbalance the voltage drop caused by the proportional gain of the control equation for the voltage amplitude. Implementation in an experimental setup with three UPS with different output rating connected in parallel shows significant reduction of the reactive lateral current, and consequent improvement of the current distribution, including employment of voltage limiters (1%), under various conditions.

  18. Impact of random and systematic recall errors and selection bias in case--control studies on mobile phone use and brain tumors in adolescents (CEFALO study).

    PubMed

    Aydin, Denis; Feychting, Maria; Schüz, Joachim; Andersen, Tina Veje; Poulsen, Aslak Harbo; Prochazka, Michaela; Klaeboe, Lars; Kuehni, Claudia E; Tynes, Tore; Röösli, Martin

    2011-07-01

    Whether the use of mobile phones is a risk factor for brain tumors in adolescents is currently being studied. Case--control studies investigating this possible relationship are prone to recall error and selection bias. We assessed the potential impact of random and systematic recall error and selection bias on odds ratios (ORs) by performing simulations based on real data from an ongoing case--control study of mobile phones and brain tumor risk in children and adolescents (CEFALO study). Simulations were conducted for two mobile phone exposure categories: regular and heavy use. Our choice of levels of recall error was guided by a validation study that compared objective network operator data with the self-reported amount of mobile phone use in CEFALO. In our validation study, cases overestimated their number of calls by 9% on average and controls by 34%. Cases also overestimated their duration of calls by 52% on average and controls by 163%. The participation rates in CEFALO were 83% for cases and 71% for controls. In a variety of scenarios, the combined impact of recall error and selection bias on the estimated ORs was complex. These simulations are useful for the interpretation of previous case-control studies on brain tumor and mobile phone use in adults as well as for the interpretation of future studies on adolescents.

  19. Comparing tumor rates in current and historical control groups in rodent cancer bioassays.

    PubMed

    Dinse, Gregg E; Peddada, Shyamal D

    2011-02-01

    When evaluating carcinogenicity, tumor rates from the current study are informally assessed within the context of relevant historical control tumor rates. Current rates outside the range of historical rates raise concerns. We propose a statistical procedure that formally compares tumor rates in current and historical control groups. We use a normal approximation for the null distribution of the proposed test when there are at least 5 historical control groups and the average tumor rate is above 0.5%; otherwise, we apply standard bootstrap techniques. For comparison purposes, we show that formally basing decisions on the range of historical control rates would yield unusually high false positive rates. That is, a range-based decision rule would not maintain the nominal 5% significance level and could produce Type I error rates as high as 67%. In other cases, the power could go to zero. The proposed test, however, controls Type I errors while adjusting for survival and extra variability among the historical studies. We illustrate the methods with data from a study of benzophenone. Compared to a range-based decision rule, the proposed test has several important advantages, including operating at the specified level and being applicable with as few as one historical study.

  20. Current drive and current profile control studies in the Tokamak Physics Experiment (TPX)

    NASA Astrophysics Data System (ADS)

    Bonoli, P. T.; Porkolab, M.; Sugiyama, L.; Kessel, C.

    1996-02-01

    Simulation studies of noninductive current profile control have been carried out for the Tokamak Physics Experiment (TPX).1 The predicted MHD equilibria have been analyzed for ideal ballooning stability and stability to the low-n, external kink modes. An advanced rf physics technique for off-axis current profile control has also been investigated for TPX. This scheme utilizes mode conversion and electron absorption in a D-(3He) plasma mixture.

  1. Improved model predictive control of resistive wall modes by error field estimator in EXTRAP T2R

    NASA Astrophysics Data System (ADS)

    Setiadi, A. C.; Brunsell, P. R.; Frassinetti, L.

    2016-12-01

    Many implementations of a model-based approach for toroidal plasma have shown better control performance compared to the conventional type of feedback controller. One prerequisite of model-based control is the availability of a control oriented model. This model can be obtained empirically through a systematic procedure called system identification. Such a model is used in this work to design a model predictive controller to stabilize multiple resistive wall modes in EXTRAP T2R reversed-field pinch. Model predictive control is an advanced control method that can optimize the future behaviour of a system. Furthermore, this paper will discuss an additional use of the empirical model which is to estimate the error field in EXTRAP T2R. Two potential methods are discussed that can estimate the error field. The error field estimator is then combined with the model predictive control and yields better radial magnetic field suppression.

  2. The definition of the railway position control error in the plane and profile using the optical-electronic system

    NASA Astrophysics Data System (ADS)

    Nikulin, Anton V.; Timofeev, Alexandr N.; Nekrylov, Ivan S.

    2015-05-01

    Continuous development of high-speed railway traffic in the world toughens requirements, including to the accuracy of installation and control of provision of a railway track. For the current technologies of service of a railway track using its absolute coordinates the perspective decision is creation along railway lines of a special fiducial network. In this case by means of optical-electronic systems, concerning reference points, obtaining the objective information on actual position of a railway track in a longitudinal cross-section and the plan with a margin error which isn't exceeding 1,5 mm in rather severe conditions of continuous operation of traveling machines at speeds up to 10 km/h is possible.

  3. A method on error analysis for large-aperture optical telescope control system

    NASA Astrophysics Data System (ADS)

    Su, Yanrui; Wang, Qiang; Yan, Fabao; Liu, Xiang; Huang, Yongmei

    2016-10-01

    For large-aperture optical telescope, compared with the performance of azimuth in the control system, arc second-level jitters exist in elevation under different speeds' working mode, especially low-speed working mode in the process of its acquisition, tracking and pointing. The jitters are closely related to the working speed of the elevation, resulting in the reduction of accuracy and low-speed stability of the telescope. By collecting a large number of measured data to the elevation, we do analysis on jitters in the time domain, frequency domain and space domain respectively. And the relation between jitter points and the leading speed of elevation and the corresponding space angle is concluded that the jitters perform as periodic disturbance in space domain and the period of the corresponding space angle of the jitter points is 79.1″ approximately. Then we did simulation, analysis and comparison to the influence of the disturbance sources, like PWM power level output disturbance, torque (acceleration) disturbance, speed feedback disturbance and position feedback disturbance on the elevation to find that the space periodic disturbance still exist in the elevation performance. It leads us to infer that the problems maybe exist in angle measurement unit. The telescope employs a 24-bit photoelectric encoder and we can calculate the encoder grating angular resolution as 79.1016'', which is as the corresponding angle value in the whole encoder system of one period of the subdivision signal. The value is approximately equal to the space frequency of the jitters. Therefore, the working elevation of the telescope is affected by subdivision errors and the period of the subdivision error is identical to the period of encoder grating angular. Through comprehensive consideration and mathematical analysis, that DC subdivision error of subdivision error sources causes the jitters is determined, which is verified in the practical engineering. The method that analyze error

  4. Electrically controlled optical latch and switch requires less current

    NASA Technical Reports Server (NTRS)

    Pieczonka, W. A.; Roy, M. M.; Yeh, T. H.

    1966-01-01

    Electrically controlled optical latch consists of a sensitive phototransistor and a solid-state light source. This design requires less current to activate an optically activated switch than in prior art.

  5. Universal control and error correction in multi-qubit spin registers in diamond.

    PubMed

    Taminiau, T H; Cramer, J; van der Sar, T; Dobrovitski, V V; Hanson, R

    2014-03-01

    Quantum registers of nuclear spins coupled to electron spins of individual solid-state defects are a promising platform for quantum information processing. Pioneering experiments selected defects with favourably located nuclear spins with particularly strong hyperfine couplings. To progress towards large-scale applications, larger and deterministically available nuclear registers are highly desirable. Here, we realize universal control over multi-qubit spin registers by harnessing abundant weakly coupled nuclear spins. We use the electron spin of a nitrogen-vacancy centre in diamond to selectively initialize, control and read out carbon-13 spins in the surrounding spin bath and construct high-fidelity single- and two-qubit gates. We exploit these new capabilities to implement a three-qubit quantum-error-correction protocol and demonstrate the robustness of the encoded state against applied errors. These results transform weakly coupled nuclear spins from a source of decoherence into a reliable resource, paving the way towards extended quantum networks and surface-code quantum computing based on multi-qubit nodes.

  6. Ion beam machining error control and correction for small scale optics.

    PubMed

    Xie, Xuhui; Zhou, Lin; Dai, Yifan; Li, Shengyi

    2011-09-20

    Ion beam figuring (IBF) technology for small scale optical components is discussed. Since the small removal function can be obtained in IBF, it makes computer-controlled optical surfacing technology possible to machine precision centimeter- or millimeter-scale optical components deterministically. Using a small ion beam to machine small optical components, there are some key problems, such as small ion beam positioning on the optical surface, material removal rate, ion beam scanning pitch control on the optical surface, and so on, that must be seriously considered. The main reasons for the problems are that it is more sensitive to the above problems than a big ion beam because of its small beam diameter and lower material ratio. In this paper, we discuss these problems and their influences in machining small optical components in detail. Based on the identification-compensation principle, an iterative machining compensation method is deduced for correcting the positioning error of an ion beam with the material removal rate estimated by a selected optimal scanning pitch. Experiments on ϕ10 mm Zerodur planar and spherical samples are made, and the final surface errors are both smaller than λ/100 measured by a Zygo GPI interferometer.

  7. Application of PI Current Controller in Single Phase Inverter System Connected to Non Linear Load

    NASA Astrophysics Data System (ADS)

    Chai Anak Ajot, Tracy; Salimin, Suriana; Aziz, Roziah

    2017-08-01

    This study is concerned with the problem of network power quality when inverter systems are connected to a nonlinear load. Nonlinear loads are well known as one of the biggest source of harmonics in the power system. Besides that, inverter systems also have their nonlinearity characteristic because of the electronic components. As the inverter system is connected to nonlinear load, it resulting in harmonic distortion-related problem and draw non-sinusoidal currents in the system, thus reducing the power quality in the system. The application of Proportional Integral controller in this system is the main interest of this study. This current controller capable of reducing total harmonic distortion and improve the state of current waveform. This paper focuses on application of simple manual trial and error tuning technique to produce the optimum value for the gains. The result of study verifies the trial and error manual tuning of PI current controller in compensating harmonic distortions. Simulation and modelling of the system are successfully developed using Matlab/Simulink.

  8. Association between reading speed, cycloplegic refractive error, and oculomotor function in reading disabled children versus controls.

    PubMed

    Quaid, Patrick; Simpson, Trefford

    2013-01-01

    Approximately one in ten students aged 6 to 16 in Ontario (Canada) school boards have an individual education plan (IEP) in place due to various learning disabilities, many of which are specific to reading difficulties. The relationship between reading (specifically objectively determined reading speed and eye movement data), refractive error, and binocular vision related clinical measurements remain elusive. One hundred patients were examined in this study (50 IEP and 50 controls, age range 6 to 16 years). IEP patients were referred by three local school boards, with controls being recruited from the routine clinic population (non-IEP patients in the same age group). A comprehensive eye examination was performed on all subjects, in addition to a full binocular vision work-up and cycloplegic refraction. In addition to the cycloplegic refractive error, the following binocular vision related data was also acquired: vergence facility, vergence amplitudes, accommodative facility, accommodative amplitudes, near point of convergence, stereopsis, and a standardized symptom scoring scale. Both the IEP and control groups were also examined using the Visagraph III system, which permits recording of the following reading parameters objectively: (i) reading speed, both raw values and values compared to grade normative data, and (ii) the number of eye movements made per 100 words read. Comprehension was assessed via a questionnaire administered at the end of the reading task, with each subject requiring 80% or greater comprehension. The IEP group had significantly greater hyperopia compared to the control group on cycloplegic examination. Vergence facility was significantly correlated to (i) reading speed, (ii) number of eye movements made when reading, and (iii) a standardized symptom scoring system. Vergence facility was also significantly reduced in the IEP group versus controls. Significant differences in several other binocular vision related scores were also found. This

  9. Current Trends in Vector Control: Adapting to Selective Pressure

    DTIC Science & Technology

    2008-11-16

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP023975 TITLE: Current Trends in Vector Control: Adapting to Selective...ADP023967 thru ADP023976 UNCLASSIFIED Current Trends in Vector Control: Adapting to Selective Pressure Kendra Lawrence MAJ, Medical Service Corps...of Research, is to mitigate the products to the forefront that may fulfill risk posed by arthropods to DoD mission needs. The Department of personnel

  10. Path-tracking control of underactuated ships under tracking error constraints

    NASA Astrophysics Data System (ADS)

    Do, Khac Duc

    2015-12-01

    This paper presents a constructive design of new controllers that force underactuated ships under constant or slow time-varying sea loads to asymptotically track a parameterized reference path, that guarantees the distance from the ship to the reference path always be within a specified value. The control design is based on a global exponential disturbance observer, a transformation of the ship dynamics to an almost spherical form, an interpretation of the tracking errors in an earth-fixed frame, an introduction of dynamic variables to compensate for relaxation of the reference path generation, p-times differentiable step functions, and backstepping and Lyapunov's direct methods. The effectiveness of the proposed results is illustrated through simulations.

  11. Improving Interference Control in ADHD Patients with Transcranial Direct Current Stimulation (tDCS)

    PubMed Central

    Breitling, Carolin; Zaehle, Tino; Dannhauer, Moritz; Bonath, Björn; Tegelbeckers, Jana; Flechtner, Hans-Henning; Krauel, Kerstin

    2016-01-01

    The use of transcranial direct current stimulation (tDCS) in patients with attention deficit hyperactivity disorder (ADHD) has been suggested as a promising alternative to psychopharmacological treatment approaches due to its local and network effects on brain activation. In the current study, we investigated the impact of tDCS over the right inferior frontal gyrus (rIFG) on interference control in 21 male adolescents with ADHD and 21 age matched healthy controls aged 13–17 years, who underwent three separate sessions of tDCS (anodal, cathodal, and sham) while completing a Flanker task. Even though anodal stimulation appeared to diminish commission errors in the ADHD group, the overall analysis revealed no significant effect of tDCS. Since participants showed a considerable learning effect from the first to the second session, performance in the first session was separately analyzed. ADHD patients receiving sham stimulation in the first session showed impaired interference control compared to healthy control participants whereas ADHD patients who were exposed to anodal stimulation, showed comparable performance levels (commission errors, reaction time variability) to the control group. These results suggest that anodal tDCS of the right inferior frontal gyrus could improve interference control in patients with ADHD. PMID:27147964

  12. Improving Interference Control in ADHD Patients with Transcranial Direct Current Stimulation (tDCS).

    PubMed

    Breitling, Carolin; Zaehle, Tino; Dannhauer, Moritz; Bonath, Björn; Tegelbeckers, Jana; Flechtner, Hans-Henning; Krauel, Kerstin

    2016-01-01

    The use of transcranial direct current stimulation (tDCS) in patients with attention deficit hyperactivity disorder (ADHD) has been suggested as a promising alternative to psychopharmacological treatment approaches due to its local and network effects on brain activation. In the current study, we investigated the impact of tDCS over the right inferior frontal gyrus (rIFG) on interference control in 21 male adolescents with ADHD and 21 age matched healthy controls aged 13-17 years, who underwent three separate sessions of tDCS (anodal, cathodal, and sham) while completing a Flanker task. Even though anodal stimulation appeared to diminish commission errors in the ADHD group, the overall analysis revealed no significant effect of tDCS. Since participants showed a considerable learning effect from the first to the second session, performance in the first session was separately analyzed. ADHD patients receiving sham stimulation in the first session showed impaired interference control compared to healthy control participants whereas ADHD patients who were exposed to anodal stimulation, showed comparable performance levels (commission errors, reaction time variability) to the control group. These results suggest that anodal tDCS of the right inferior frontal gyrus could improve interference control in patients with ADHD.

  13. Novel prescribed performance neural control of a flexible air-breathing hypersonic vehicle with unknown initial errors.

    PubMed

    Bu, Xiangwei; Wu, Xiaoyan; Zhu, Fujing; Huang, Jiaqi; Ma, Zhen; Zhang, Rui

    2015-11-01

    A novel prescribed performance neural controller with unknown initial errors is addressed for the longitudinal dynamic model of a flexible air-breathing hypersonic vehicle (FAHV) subject to parametric uncertainties. Different from traditional prescribed performance control (PPC) requiring that the initial errors have to be known accurately, this paper investigates the tracking control without accurate initial errors via exploiting a new performance function. A combined neural back-stepping and minimal learning parameter (MLP) technology is employed for exploring a prescribed performance controller that provides robust tracking of velocity and altitude reference trajectories. The highlight is that the transient performance of velocity and altitude tracking errors is satisfactory and the computational load of neural approximation is low. Finally, numerical simulation results from a nonlinear FAHV model demonstrate the efficacy of the proposed strategy.

  14. Factors controlling volume errors through 2D gully erosion assessment: guidelines for optimal survey design

    NASA Astrophysics Data System (ADS)

    Castillo, Carlos; Pérez, Rafael

    2017-04-01

    The assessment of gully erosion volumes is essential for the quantification of soil losses derived from this relevant degradation process. Traditionally, 2D and 3D approaches has been applied for this purpose (Casalí et al., 2006). Although innovative 3D approaches have recently been proposed for gully volume quantification, a renewed interest can be found in literature regarding the useful information that cross-section analysis still provides in gully erosion research. Moreover, the application of methods based on 2D approaches can be the most cost-effective approach in many situations such as preliminary studies with low accuracy requirements or surveys under time or budget constraints. The main aim of this work is to examine the key factors controlling volume error variability in 2D gully assessment by means of a stochastic experiment involving a Monte Carlo analysis over synthetic gully profiles in order to 1) contribute to a better understanding of the drivers and magnitude of gully erosion 2D-surveys uncertainty and 2) provide guidelines for optimal survey designs. Owing to the stochastic properties of error generation in 2D volume assessment, a statistical approach was followed to generate a large and significant set of gully reach configurations to evaluate quantitatively the influence of the main factors controlling the uncertainty of the volume assessment. For this purpose, a simulation algorithm in Matlab® code was written, involving the following stages: - Generation of synthetic gully area profiles with different degrees of complexity (characterized by the cross-section variability) - Simulation of field measurements characterised by a survey intensity and the precision of the measurement method - Quantification of the volume error uncertainty as a function of the key factors In this communication we will present the relationships between volume error and the studied factors and propose guidelines for 2D field surveys based on the minimal survey

  15. Detection and reconstruction of error control codes for engineered and biological regulatory systems.

    SciTech Connect

    May, Elebeoba Eni; Rintoul, Mark Daniel; Johnston, Anna Marie; Pryor, Richard J.; Hart, William Eugene; Watson, Jean-Paul

    2003-10-01

    determining similar parameters for a received, noisy, error-control encoded data set. In addition to these goals, we initiated exploration of algorithmic approaches to determine if a data set could be approximated with an error-control code and performed initial investigations into optimization based methodologies for extracting the encoding algorithm given the coding rate of an encoded noise-free and noisy data stream.

  16. Calibration of an instrumented treadmill using a precision-controlled device with artificial neural network-based error corrections.

    PubMed

    Hsieh, Hong-Jung; Lin, Hsiu-Chen; Lu, Hsuan-Lun; Chen, Ting-Yi; Lu, Tung-Wu

    2016-03-01

    Instrumented treadmills (ITs) are used to measure reaction forces (RF) and center of pressure (COP) movements for gait and balance assessment. Regular in situ calibration is essential to ensure their accuracy and to identify conditions when a factory re-calibration is needed. The current study aimed to develop and calibrate in situ an IT using a portable, precision-controlled calibration device with an artificial neural network (ANN)-based correction method. The calibration device was used to apply static and dynamic calibrating loads to the surface of the IT at 189 and 25 grid-points, respectively, at four belt speeds (0, 4, 6 and 8 km/h) without the need of a preset template. Part of the applied and measured RF and COP were used to train a threelayered, back-propagation ANN model while the rest of the data were used to evaluate the performance of the ANN. The percent errors of Fz and errors of the Px and Py were significantly decreased from a maximum of -1.15%, -1.64 mm and -0.73 mm to 0.02%, 0.02 mm and 0.03 mm during static calibration, respectively. During dynamic calibration, the corresponding values were decreasing from -3.65%, 2.58 mm and -4.92 mm to 0.30%, -0.14 mm and -0.47 mm, respectively. The results suggest that the calibration device and associated ANN will be useful for correcting measurement errors in vertical loads and COP for ITs. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. In Your Face: Risk of Punishment Enhances Cognitive Control and Error-Related Activity in the Corrugator Supercilii Muscle.

    PubMed

    Lindström, Björn R; Mattsson-Mårn, Isak Berglund; Golkar, Armita; Olsson, Andreas

    2013-01-01

    Cognitive control is needed when mistakes have consequences, especially when such consequences are potentially harmful. However, little is known about how the aversive consequences of deficient control affect behavior. To address this issue, participants performed a two-choice response time task where error commissions were expected to be punished by electric shocks during certain blocks. By manipulating (1) the perceived punishment risk (no, low, high) associated with error commissions, and (2) response conflict (low, high), we showed that motivation to avoid punishment enhanced performance during high response conflict. As a novel index of the processes enabling successful cognitive control under threat, we explored electromyographic activity in the corrugator supercilii (cEMG) muscle of the upper face. The corrugator supercilii is partially controlled by the anterior midcingulate cortex (aMCC) which is sensitive to negative affect, pain and cognitive control. As hypothesized, the cEMG exhibited several key similarities with the core temporal and functional characteristics of the Error-Related Negativity (ERN) ERP component, the hallmark index of cognitive control elicited by performance errors, and which has been linked to the aMCC. The cEMG was amplified within 100 ms of error commissions (the same time-window as the ERN), particularly during the high punishment risk condition where errors would be most aversive. Furthermore, similar to the ERN, the magnitude of error cEMG predicted post-error response time slowing. Our results suggest that cEMG activity can serve as an index of avoidance motivated control, which is instrumental to adaptive cognitive control when consequences are potentially harmful.

  18. Demonstration of sufficient control for two rounds of quantum error correction in a solid state ensemble quantum information processor.

    PubMed

    Moussa, Osama; Baugh, Jonathan; Ryan, Colm A; Laflamme, Raymond

    2011-10-14

    We report the implementation of a 3-qubit quantum error-correction code on a quantum information processor realized by the magnetic resonance of carbon nuclei in a single crystal of malonic acid. The code corrects for phase errors induced on the qubits due to imperfect decoupling of the magnetic environment represented by nearby spins, as well as unwanted evolution under the internal Hamiltonian. We also experimentally demonstrate sufficiently high-fidelity control to implement two rounds of quantum error correction. This is a demonstration of state-of-the-art control in solid state nuclear magnetic resonance, a leading test bed for the implementation of quantum algorithms.

  19. Bio-inspired adaptive feedback error learning architecture for motor control.

    PubMed

    Tolu, Silvia; Vanegas, Mauricio; Luque, Niceto R; Garrido, Jesús A; Ros, Eduardo

    2012-10-01

    This study proposes an adaptive control architecture based on an accurate regression method called Locally Weighted Projection Regression (LWPR) and on a bio-inspired module, such as a cerebellar-like engine. This hybrid architecture takes full advantage of the machine learning module (LWPR kernel) to abstract an optimized representation of the sensorimotor space while the cerebellar component integrates this to generate corrective terms in the framework of a control task. Furthermore, we illustrate how the use of a simple adaptive error feedback term allows to use the proposed architecture even in the absence of an accurate analytic reference model. The presented approach achieves an accurate control with low gain corrective terms (for compliant control schemes). We evaluate the contribution of the different components of the proposed scheme comparing the obtained performance with alternative approaches. Then, we show that the presented architecture can be used for accurate manipulation of different objects when their physical properties are not directly known by the controller. We evaluate how the scheme scales for simulated plants of high Degrees of Freedom (7-DOFs).

  20. The flexible grinding technology based on the electric current control

    NASA Astrophysics Data System (ADS)

    Peng, Liwen; Yao, Bin; Li, Fei; Wang, Xiao; Yao, Boshi

    2012-01-01

    A flexible grinding technology based on the electric current control is presented to resolve the problem of low rigidity of PCB during grinding, the thickness of which varies from 0.1mm up to 3.5 mm. The comparative results between the real-time current and the setting current in the process of grinding control the frequency and the number of servo pulse, and then the servo motor adjusts the grinding depth of brushing roller at several different rotational speeds, namely, realizing the constant grinding force during grinding. The results show that the PCB can be grinded efficiently and accurately by means of the flexible grinding technology based on the electric current control.

  1. Controlling ultrafast currents by the nonlinear photogalvanic effect

    NASA Astrophysics Data System (ADS)

    Wachter, Georg; Sato, Shunsuke A.; Floss, Isabella; Lemell, Christoph; Tong, Xiao-Min; Yabana, Kazuhiro; Burgdörfer, Joachim

    2015-12-01

    We investigate the effect of broken inversion symmetry on the generation and control of ultrafast currents in a transparent dielectric (SiO2) by strong femtosecond optical laser pulses. Ab initio simulations based on time-dependent density functional theory predict ultrafast direct currents that can be viewed as a nonlinear photogalvanic effect. Most surprisingly, the direction of the current undergoes a sudden reversal above a critical threshold value of laser intensity of about {I}{{c}}˜ 3× {10}13 W cm-2. We trace this switching to the transition from nonlinear polarisation currents to the tunnelling excitation regime. The latter is found to be sensitive to the relative orientation between laser polarisation and chemical bonds. We demonstrate control of the ultrafast currents by the time delay between two laser pulses. While two temporally separated laser pulses lead to currents along one direction their temporal overlap can reverse the current. We find the ultrafast current control by the nonlinear photogalvanic effect to be remarkably robust and insensitive to the laser-pulse shape and the carrier-envelope phase.

  2. Error-prone translesion replication of damaged DNA suppresses skin carcinogenesis by controlling inflammatory hyperplasia

    PubMed Central

    Tsaalbi-Shtylik, Anastasia; Verspuy, Johan W. A.; Jansen, Jacob G.; Rebel, Heggert; Carlée, Leone M.; van der Valk, Martin A.; Jonkers, Jos; de Gruijl, Frank R.; de Wind, Niels

    2009-01-01

    The induction of skin cancer involves both mutagenic and proliferative responses of the epidermis to ultraviolet (UV) light. It is believed that tumor initiation requires the mutagenic replication of damaged DNA by translesion synthesis (TLS) pathways. The mechanistic basis for the induction of proliferation, providing tumor promotion, is poorly understood. Here, we have investigated the role of TLS in the initiation and promotion of skin carcinogenesis, using a sensitive nucleotide excision repair-deficient mouse model that carries a hypomorphic allele of the error-prone TLS gene Rev1. Despite a defect in UV-induced mutagenesis, skin carcinogenesis was accelerated in these mice. This paradoxical phenotype was caused by the induction of inflammatory hyperplasia of the mutant skin that provides strong tumor promotion. The induction of hyperplasia was associated with mild and transient replicational stress of the UV-damaged genome, triggering DNA damage signaling and senescence. The concomitant expression of Interleukin-6 (IL-6) is in agreement with an executive role for IL-6 and possibly other cytokines in the autocrine induction of senescence and the paracrine induction of inflammatory hyperplasia. In conclusion, error-prone TLS suppresses tumor-promoting activities of UV light, thereby controlling skin carcinogenesis. PMID:20007784

  3. Exploring the Current Landscape of Intravenous Infusion Practices and Errors (ECLIPSE): protocol for a mixed-methods observational study.

    PubMed

    Blandford, Ann; Furniss, Dominic; Lyons, Imogen; Chumbley, Gill; Iacovides, Ioanna; Wei, Li; Cox, Anna; Mayer, Astrid; Schnock, Kumiko; Bates, David Westfall; Dykes, Patricia C; Bell, Helen; Franklin, Bryony Dean

    2016-03-03

    Intravenous medication is essential for many hospital inpatients. However, providing intravenous therapy is complex and errors are common. 'Smart pumps' incorporating dose error reduction software have been widely advocated to reduce error. However, little is known about their effect on patient safety, how they are used or their likely impact. This study will explore the landscape of intravenous medication infusion practices and errors in English hospitals and how smart pumps may relate to the prevalence of medication administration errors. This is a mixed-methods study involving an observational quantitative point prevalence study to determine the frequency and types of errors that occur in the infusion of intravenous medication, and qualitative interviews with hospital staff to better understand infusion practices and the contexts in which errors occur. The study will involve 5 clinical areas (critical care, general medicine, general surgery, paediatrics and oncology), across 14 purposively sampled acute hospitals and 2 paediatric hospitals to cover a range of intravenous infusion practices. Data collectors will compare each infusion running at the time of data collection against the patient's medication orders to identify any discrepancies. The potential clinical importance of errors will be assessed. Quantitative data will be analysed descriptively; interviews will be analysed using thematic analysis. Ethical approval has been obtained from an NHS Research Ethics Committee (14/SC/0290); local approvals will be sought from each participating organisation. Findings will be published in peer-reviewed journals and presented at conferences for academic and health professional audiences. Results will also be fed back to participating organisations to inform local policy, training and procurement. Aggregated findings will inform the debate on costs and benefits of the NHS investing in smart pump technology, and what other changes may need to be made to ensure

  4. Exploring the Current Landscape of Intravenous Infusion Practices and Errors (ECLIPSE): protocol for a mixed-methods observational study

    PubMed Central

    Blandford, Ann; Furniss, Dominic; Chumbley, Gill; Iacovides, Ioanna; Wei, Li; Cox, Anna; Mayer, Astrid; Schnock, Kumiko; Bates, David Westfall; Dykes, Patricia C; Bell, Helen; Dean Franklin, Bryony

    2016-01-01

    Introduction Intravenous medication is essential for many hospital inpatients. However, providing intravenous therapy is complex and errors are common. ‘Smart pumps’ incorporating dose error reduction software have been widely advocated to reduce error. However, little is known about their effect on patient safety, how they are used or their likely impact. This study will explore the landscape of intravenous medication infusion practices and errors in English hospitals and how smart pumps may relate to the prevalence of medication administration errors. Methods and analysis This is a mixed-methods study involving an observational quantitative point prevalence study to determine the frequency and types of errors that occur in the infusion of intravenous medication, and qualitative interviews with hospital staff to better understand infusion practices and the contexts in which errors occur. The study will involve 5 clinical areas (critical care, general medicine, general surgery, paediatrics and oncology), across 14 purposively sampled acute hospitals and 2 paediatric hospitals to cover a range of intravenous infusion practices. Data collectors will compare each infusion running at the time of data collection against the patient's medication orders to identify any discrepancies. The potential clinical importance of errors will be assessed. Quantitative data will be analysed descriptively; interviews will be analysed using thematic analysis. Ethics and dissemination Ethical approval has been obtained from an NHS Research Ethics Committee (14/SC/0290); local approvals will be sought from each participating organisation. Findings will be published in peer-reviewed journals and presented at conferences for academic and health professional audiences. Results will also be fed back to participating organisations to inform local policy, training and procurement. Aggregated findings will inform the debate on costs and benefits of the NHS investing in smart pump technology

  5. Systematic review of ERP and fMRI studies investigating inhibitory control and error processing in people with substance dependence and behavioural addictions

    PubMed Central

    Luijten, Maartje; Machielsen, Marise W.J.; Veltman, Dick J.; Hester, Robert; de Haan, Lieuwe; Franken, Ingmar H.A.

    2014-01-01

    Background Several current theories emphasize the role of cognitive control in addiction. The present review evaluates neural deficits in the domains of inhibitory control and error processing in individuals with substance dependence and in those showing excessive addiction-like behaviours. The combined evaluation of event-related potential (ERP) and functional magnetic resonance imaging (fMRI) findings in the present review offers unique information on neural deficits in addicted individuals. Methods We selected 19 ERP and 22 fMRI studies using stop-signal, go/no-go or Flanker paradigms based on a search of PubMed and Embase. Results The most consistent findings in addicted individuals relative to healthy controls were lower N2, error-related negativity and error positivity amplitudes as well as hypoactivation in the anterior cingulate cortex (ACC), inferior frontal gyrus and dorsolateral prefrontal cortex. These neural deficits, however, were not always associated with impaired task performance. With regard to behavioural addictions, some evidence has been found for similar neural deficits; however, studies are scarce and results are not yet conclusive. Differences among the major classes of substances of abuse were identified and involve stronger neural responses to errors in individuals with alcohol dependence versus weaker neural responses to errors in other substance-dependent populations. Limitations Task design and analysis techniques vary across studies, thereby reducing comparability among studies and the potential of clinical use of these measures. Conclusion Current addiction theories were supported by identifying consistent abnormalities in prefrontal brain function in individuals with addiction. An integrative model is proposed, suggesting that neural deficits in the dorsal ACC may constitute a hallmark neurocognitive deficit underlying addictive behaviours, such as loss of control. PMID:24359877

  6. The impact of a brief mindfulness meditation intervention on cognitive control and error-related performance monitoring

    PubMed Central

    Larson, Michael J.; Steffen, Patrick R.; Primosch, Mark

    2013-01-01

    Meditation is associated with positive health behaviors and improved cognitive control. One mechanism for the relationship between meditation and cognitive control is changes in activity of the anterior cingulate cortex-mediated neural pathways. The error-related negativity (ERN) and error positivity (Pe) components of the scalp-recorded event-related potential (ERP) represent cingulate-mediated functions of performance monitoring that may be modulated by mindfulness meditation. We utilized a flanker task, an experimental design, and a brief mindfulness intervention in a sample of 55 healthy non-meditators (n = 28 randomly assigned to the mindfulness group and n = 27 randomly assigned to the control group) to examine autonomic nervous system functions as measured by blood pressure and indices of cognitive control as measured by response times, error rates, post-error slowing, and the ERN and Pe components of the ERP. Systolic blood pressure significantly differentiated groups following the mindfulness intervention and following the flanker task. There were non-significant differences between the mindfulness and control groups for response times, post-error slowing, and error rates on the flanker task. Amplitude and latency of the ERN did not differ between groups; however, amplitude of the Pe was significantly smaller in individuals in the mindfulness group than in the control group. Findings suggest that a brief mindfulness intervention is associated with reduced autonomic arousal and decreased amplitude of the Pe, an ERP associated with error awareness, attention, and motivational salience, but does not alter amplitude of the ERN or behavioral performance. Implications for brief mindfulness interventions and state vs. trait affect theories of the ERN are discussed. Future research examining graded levels of mindfulness and tracking error awareness will clarify relationship between mindfulness and performance monitoring. PMID:23847491

  7. The impact of a brief mindfulness meditation intervention on cognitive control and error-related performance monitoring.

    PubMed

    Larson, Michael J; Steffen, Patrick R; Primosch, Mark

    2013-01-01

    Meditation is associated with positive health behaviors and improved cognitive control. One mechanism for the relationship between meditation and cognitive control is changes in activity of the anterior cingulate cortex-mediated neural pathways. The error-related negativity (ERN) and error positivity (Pe) components of the scalp-recorded event-related potential (ERP) represent cingulate-mediated functions of performance monitoring that may be modulated by mindfulness meditation. We utilized a flanker task, an experimental design, and a brief mindfulness intervention in a sample of 55 healthy non-meditators (n = 28 randomly assigned to the mindfulness group and n = 27 randomly assigned to the control group) to examine autonomic nervous system functions as measured by blood pressure and indices of cognitive control as measured by response times, error rates, post-error slowing, and the ERN and Pe components of the ERP. Systolic blood pressure significantly differentiated groups following the mindfulness intervention and following the flanker task. There were non-significant differences between the mindfulness and control groups for response times, post-error slowing, and error rates on the flanker task. Amplitude and latency of the ERN did not differ between groups; however, amplitude of the Pe was significantly smaller in individuals in the mindfulness group than in the control group. Findings suggest that a brief mindfulness intervention is associated with reduced autonomic arousal and decreased amplitude of the Pe, an ERP associated with error awareness, attention, and motivational salience, but does not alter amplitude of the ERN or behavioral performance. Implications for brief mindfulness interventions and state vs. trait affect theories of the ERN are discussed. Future research examining graded levels of mindfulness and tracking error awareness will clarify relationship between mindfulness and performance monitoring.

  8. Design implementation and control of MRAS error dynamics. [Model-Reference Adaptive System

    NASA Technical Reports Server (NTRS)

    Colburn, B. K.; Boland, J. S., III

    1974-01-01

    Use is made of linearized error characteristic equation for model-reference adaptive systems to determine a parameter adjustment rule for obtaining time-invariant error dynamics. Theoretical justification of error stability is given and an illustrative example included to demonstrate the utility of the proposed technique.

  9. Online machining error estimation method of numerical control gear grinding machine tool based on data analysis of internal sensors

    NASA Astrophysics Data System (ADS)

    Zhao, Fei; Zhang, Chi; Yang, Guilin; Chen, Chinyin

    2016-12-01

    This paper presents an online estimation method of cutting error by analyzing of internal sensor readings. The internal sensors of numerical control (NC) machine tool are selected to avoid installation problem. The estimation mathematic model of cutting error was proposed to compute the relative position of cutting point and tool center point (TCP) from internal sensor readings based on cutting theory of gear. In order to verify the effectiveness of the proposed model, it was simulated and experimented in gear generating grinding process. The cutting error of gear was estimated and the factors which induce cutting error were analyzed. The simulation and experiments verify that the proposed approach is an efficient way to estimate the cutting error of work-piece during machining process.

  10. Partially Key Distribution with Public Key Cryptosystem Based on Error Control Codes

    NASA Astrophysics Data System (ADS)

    Tavallaei, Saeed Ebadi; Falahati, Abolfazl

    Due to the low level of security in public key cryptosystems based on number theory, fundamental difficulties such as "key escrow" in Public Key Infrastructure (PKI) and a secure channel in ID-based cryptography, a new key distribution cryptosystem based on Error Control Codes (ECC) is proposed . This idea is done by some modification on McEliece cryptosystem. The security of ECC cryptosystem obtains from the NP-Completeness of block codes decoding. The capability of generating public keys with variable lengths which is suitable for different applications will be provided by using ECC. It seems that usage of these cryptosystems because of decreasing in the security of cryptosystems based on number theory and increasing the lengths of their keys would be unavoidable in future.

  11. Method to control depth error when ablating human dentin with numerically controlled picosecond laser: a preliminary study.

    PubMed

    Sun, Yuchun; Yuan, Fusong; Lv, Peijun; Wang, Dangxiao; Wang, Lei; Wang, Yong

    2015-07-01

    A three-axis numerically controlled picosecond laser was used to ablate dentin to investigate the quantitative relationships among the number of additive pulse layers in two-dimensional scans starting from the focal plane, step size along the normal of the focal plane (focal plane normal), and ablation depth error. A method to control the ablation depth error, suitable to control stepping along the focal plane normal, was preliminarily established. Twenty-four freshly removed mandibular first molars were cut transversely along the long axis of the crown and prepared as 48 tooth sample slices with approximately flat surfaces. Forty-two slices were used in the first section. The picosecond laser was 1,064 nm in wavelength, 3 W in power, and 10 kHz in repetition frequency. For a varying number (n = 5-70) of focal plane additive pulse layers (14 groups, three repetitions each), two-dimensional scanning and ablation were performed on the dentin regions of the tooth sample slices, which were fixed on the focal plane. The ablation depth, d, was measured, and the quantitative function between n and d was established. Six slices were used in the second section. The function was used to calculate and set the timing of stepwise increments, and the single-step size along the focal plane normal was d micrometer after ablation of n layers (n = 5-50; 10 groups, six repetitions each). Each sample underwent three-dimensional scanning and ablation to produce 2 × 2-mm square cavities. The difference, e, between the measured cavity depth and theoretical value was calculated, along with the difference, e 1, between the measured average ablation depth of a single-step along the focal plane normal and theoretical value. Values of n and d corresponding to the minimum values of e and e 1, respectively, were obtained. In two-dimensional ablation, d was largest (720.61 μm) when n = 65 and smallest when n = 5 (45.00 μm). Linear regression yielded the quantitative

  12. Analysis of Solar Two heliostat tracking error sources

    SciTech Connect

    Stone, K.W.; Jones, S.A.

    1999-07-01

    This paper explores the geometrical errors that reduce heliostat tracking accuracy at Solar Two. The basic heliostat control architecture is described. Then, the three dominant error sources are described and their effect on heliostat tracking is visually illustrated. The strategy currently used to minimize, but not truly correct, these error sources is also shown. Finally, a novel approach to minimizing error is presented.

  13. Analysis of Solar Two Heliostat Tracking Error Sources

    SciTech Connect

    Jones, S.A.; Stone, K.W.

    1999-01-28

    This paper explores the geometrical errors that reduce heliostat tracking accuracy at Solar Two. The basic heliostat control architecture is described. Then, the three dominant error sources are described and their effect on heliostat tracking is visually illustrated. The strategy currently used to minimize, but not truly correct, these error sources is also shown. Finally, a novel approach to minimizing error is presented.

  14. Piezocomposite Actuator Arrays for Correcting and Controlling Wavefront Error in Reflectors

    NASA Technical Reports Server (NTRS)

    Bradford, Samuel Case; Peterson, Lee D.; Ohara, Catherine M.; Shi, Fang; Agnes, Greg S.; Hoffman, Samuel M.; Wilkie, William Keats

    2012-01-01

    Three reflectors have been developed and tested to assess the performance of a distributed network of piezocomposite actuators for correcting thermal deformations and total wave-front error. The primary testbed article is an active composite reflector, composed of a spherically curved panel with a graphite face sheet and aluminum honeycomb core composite, and then augmented with a network of 90 distributed piezoelectric composite actuators. The piezoelectric actuator system may be used for correcting as-built residual shape errors, and for controlling low-order, thermally-induced quasi-static distortions of the panel. In this study, thermally-induced surface deformations of 1 to 5 microns were deliberately introduced onto the reflector, then measured using a speckle holography interferometer system. The reflector surface figure was subsequently corrected to a tolerance of 50 nm using the actuators embedded in the reflector's back face sheet. Two additional test articles were constructed: a borosilicate at window at 150 mm diameter with 18 actuators bonded to the back surface; and a direct metal laser sintered reflector with spherical curvature, 230 mm diameter, and 12 actuators bonded to the back surface. In the case of the glass reflector, absolute measurements were performed with an interferometer and the absolute surface was corrected. These test articles were evaluated to determine their absolute surface control capabilities, as well as to assess a multiphysics modeling effort developed under this program for the prediction of active reflector response. This paper will describe the design, construction, and testing of active reflector systems under thermal loads, and subsequent correction of surface shape via distributed peizeoelctric actuation.

  15. Piezocomposite Actuator Arrays for Correcting and Controlling Wavefront Error in Reflectors

    NASA Technical Reports Server (NTRS)

    Bradford, Samuel Case; Peterson, Lee D.; Ohara, Catherine M.; Shi, Fang; Agnes, Greg S.; Hoffman, Samuel M.; Wilkie, William Keats

    2012-01-01

    Three reflectors have been developed and tested to assess the performance of a distributed network of piezocomposite actuators for correcting thermal deformations and total wave-front error. The primary testbed article is an active composite reflector, composed of a spherically curved panel with a graphite face sheet and aluminum honeycomb core composite, and then augmented with a network of 90 distributed piezoelectric composite actuators. The piezoelectric actuator system may be used for correcting as-built residual shape errors, and for controlling low-order, thermally-induced quasi-static distortions of the panel. In this study, thermally-induced surface deformations of 1 to 5 microns were deliberately introduced onto the reflector, then measured using a speckle holography interferometer system. The reflector surface figure was subsequently corrected to a tolerance of 50 nm using the actuators embedded in the reflector's back face sheet. Two additional test articles were constructed: a borosilicate at window at 150 mm diameter with 18 actuators bonded to the back surface; and a direct metal laser sintered reflector with spherical curvature, 230 mm diameter, and 12 actuators bonded to the back surface. In the case of the glass reflector, absolute measurements were performed with an interferometer and the absolute surface was corrected. These test articles were evaluated to determine their absolute surface control capabilities, as well as to assess a multiphysics modeling effort developed under this program for the prediction of active reflector response. This paper will describe the design, construction, and testing of active reflector systems under thermal loads, and subsequent correction of surface shape via distributed peizeoelctric actuation.

  16. Current drive and current profile control studies in the Tokamak Physics Experiment (TPX)

    SciTech Connect

    Bonoli, P.T.; Porkolab, M.; Sugiyama, L.; Kessel, C.

    1996-02-01

    Simulation studies of noninductive current profile control have been carried out for the Tokamak Physics Experiment (TPX).{sup 1} The predicted MHD equilibria have been analyzed for ideal ballooning stability and stability to the low-{ital n}, external kink modes. An advanced rf physics technique for off-axis current profile control has also been investigated for TPX. This scheme utilizes mode conversion and electron absorption in a D-({sup 3}He) plasma mixture. {copyright} {ital 1996 American Institute of Physics.}

  17. Adaptive rate error control through the use of diversity combining and majority logic decoding in a hybrid-ARQ protocol

    NASA Astrophysics Data System (ADS)

    Wicker, Stephen B.

    The author demonstrates an adaptive rate coding system based on the majority logic decoding of convolutional codes. The proposed system retains the high-data-rate capability of FEC (forward error correction) majority logic decoders while providing an adaptive code rate and a significant improvement in error protection through the incorporation of diversity combining and hybrid-ARQ (automatic repeat request) techniques. It is shown through analysis and simulation that this error control system provides a high level of data reliability at the expense of a minimal reduction in throughput.

  18. The Institute for Safe Medication Practices and Poison Control Centers: Collaborating to Prevent Medication Errors and Unintentional Poisonings.

    PubMed

    Vaida, Allen J

    2015-06-01

    This article provides an overview on the Institute for Safe Medication Practices (ISMP), the only independent nonprofit organization in the USA devoted to the prevention of medication errors. ISMP developed the national Medication Errors Reporting Program (MERP) and investigates and analyzes errors in order to formulate recommendations to prevent further occurrences. ISMP works closely with the US Food and Drug Administration (FDA), drug manufacturers, professional organizations, and others to promote changes in package design, practice standards, and healthcare practitioner and consumer education. By collaborating with ISMP to share and disseminate information, Poison Control centers, emergency departments, and toxicologists can help decrease unintentional and accidental poisonings.

  19. Switchable spin-current source controlled by magnetic domain walls.

    PubMed

    Savero Torres, W; Laczkowski, P; Nguyen, V D; Rojas Sanchez, J C; Vila, L; Marty, A; Jamet, M; Attané, J P

    2014-07-09

    Using nonlocal spin injection, spin-orbit coupling, or spincaloritronic effects, the manipulation of pure spin currents in nanostructures underlies the development of new spintronic devices. Here, we demonstrate the possibility to create switchable pure spin current sources, controlled by magnetic domain walls. When the domain wall is located at a given point of the magnetic circuit, a pure spin current is injected into a nonmagnetic wire. Using the reciprocal measurement configuration, we demonstrate that the proposed device can also be used as a pure spin current detector. Thanks to its simple geometry, this device can be easily implemented in spintronics applications; in particular, a single current source can be used both to induce the domain wall motion and to generate the spin signal.

  20. Research on controlling middle spatial frequency error of high gradient precise aspheric by pitch tool

    NASA Astrophysics Data System (ADS)

    Wang, Jia; Hou, Xi; Wan, Yongjian; Shi, Chunyan; Zhong, Xianyun

    2016-09-01

    Extreme optical fabrication projects known as EUV and X-ray optic systems, which are representative of today's advanced optical manufacturing technology level, have special requirements for the optical surface quality. In synchroton radiation (SR) beamlines, mirrors of high shape accuracy is always used in grazing incidence. In nanolithograph systems, middle spatial frequency errors always lead to small-angle scattering or flare that reduces the contrast of the image. The slope error is defined for a given horizontal length, the increase or decrease in form error at the end point relative to the starting point is measured. The quality of reflective optical elements can be described by their deviation from ideal shape at different spatial frequencies. Usually one distinguishes between the figure error, the low spatial error part ranging from aperture length to 1mm frequencies, and the mid-high spatial error part from 1mm to 1 μm and from1 μm to some 10 nm spatial frequencies, respectively. Firstly, this paper will disscuss the relationship between slope error and middle spatial frequency error, which both describe the optical surface error along with the form profile. Then, experimental researches will be conducted on a high gradient precise aspheric with pitch tool, which aim to restraining the middle spatial frequency error.

  1. A Sensorless Predictive Current Controlled Boost Converter by Using an EKF with Load Variation Effect Elimination Function

    PubMed Central

    Tong, Qiaoling; Chen, Chen; Zhang, Qiao; Zou, Xuecheng

    2015-01-01

    To realize accurate current control for a boost converter, a precise measurement of the inductor current is required to achieve high resolution current regulating. Current sensors are widely used to measure the inductor current. However, the current sensors and their processing circuits significantly contribute extra hardware cost, delay and noise to the system. They can also harm the system reliability. Therefore, current sensorless control techniques can bring cost effective and reliable solutions for various boost converter applications. According to the derived accurate model, which contains a number of parasitics, the boost converter is a nonlinear system. An Extended Kalman Filter (EKF) is proposed for inductor current estimation and output voltage filtering. With this approach, the system can have the same advantages as sensored current control mode. To implement EKF, the load value is necessary. However, the load may vary from time to time. This can lead to errors of current estimation and filtered output voltage. To solve this issue, a load variation elimination effect elimination (LVEE) module is added. In addition, a predictive average current controller is used to regulate the current. Compared with conventional voltage controlled system, the transient response is greatly improved since it only takes two switching cycles for the current to reach its reference. Finally, experimental results are presented to verify the stable operation and output tracking capability for large-signal transients of the proposed algorithm. PMID:25928061

  2. Effects of model error on control of large flexible space antenna with comparisons of decoupled and linear quadratic regulator control procedures

    NASA Technical Reports Server (NTRS)

    Hamer, H. A.; Johnson, K. G.

    1986-01-01

    An analysis was performed to determine the effects of model error on the control of a large flexible space antenna. Control was achieved by employing two three-axis control-moment gyros (CMG's) located on the antenna column. State variables were estimated by including an observer in the control loop that used attitude and attitude-rate sensors on the column. Errors were assumed to exist in the individual model parameters: modal frequency, modal damping, mode slope (control-influence coefficients), and moment of inertia. Their effects on control-system performance were analyzed either for (1) nulling initial disturbances in the rigid-body modes, or (2) nulling initial disturbances in the first three flexible modes. The study includes the effects on stability, time to null, and control requirements (defined as maximum torque and total momentum), as well as on the accuracy of obtaining initial estimates of the disturbances. The effects on the transients of the undisturbed modes are also included. The results, which are compared for decoupled and linear quadratic regulator (LQR) control procedures, are shown in tabular form, parametric plots, and as sample time histories of modal-amplitude and control responses. Results of the analysis showed that the effects of model errors on the control-system performance were generally comparable for both control procedures. The effect of mode-slope error was the most serious of all model errors.

  3. Error-enhancing robot therapy to induce motor control improvement in childhood onset primary dystonia.

    PubMed

    Casellato, Claudia; Pedrocchi, Alessandra; Zorzi, Giovanna; Rizzi, Giorgio; Ferrigno, Giancarlo; Nardocci, Nardo

    2012-07-23

    Robot-generated deviating forces during multijoint reaching movements have been applied to investigate motor control and to tune neuromotor adaptation. Can the application of force to limbs improve motor learning? In this framework, the response to altered dynamic environments of children affected by primary dystonia has never been studied. As preliminary pilot study, eleven children with primary dystonia and eleven age-matched healthy control subjects were asked to perform upper limb movements, triangle-reaching (three directions) and circle-writing, using a haptic robot interacting with ad-hoc developed task-specific visual interfaces. Three dynamic conditions were provided, null additive external force (A), constant disturbing force (B) and deactivation of the additive external force again (C). The path length for each trial was computed, from the recorded position data and interaction events. The results show that the disturbing force affects significantly the movement outcomes in healthy but not in dystonic subjects, already compromised in the reference condition: the external alteration uncalibrates the healthy sensorimotor system, while the dystonic one is already strongly uncalibrated. The lack of systematic compensation for perturbation effects during B condition is reflected into the absence of after-effects in C condition, which would be the evidence that CNS generates a prediction of the perturbing forces using an internal model of the environment.The most promising finding is that in dystonic population the altered dynamic exposure seems to induce a subsequent improvement, i.e. a beneficial after-effect in terms of optimal path control, compared with the correspondent reference movement outcome. The short-time error-enhancing training in dystonia could represent an effective approach for motor performance improvement, since the exposure to controlled dynamic alterations induces a refining of the existing but strongly imprecise motor scheme and

  4. Improving Area Control Error Diversity Interchange (ADI) Program by Incorporating Congestion Constraints

    SciTech Connect

    Zhou, Ning; Etingov, Pavel V.; Makarov, Yuri V.; Guttromson, Ross T.; McManus, Bart

    2010-04-30

    The area control error (ACE) determines how much a balancing authority (BA) needs to move its regulating units to meet mandatory control performance standard requirements. Regulation is an expensive resource that could cost several hundred million dollars a year for a BA. The amount of regulation needed in a system is increasing with more intermittent generation resources added to the system. The ACE diversity interchange (ADI) program provides a tool for reducing the regulation requirement by combining ACEs from several participating BAs followed by sharing the total ACE among all participating balancing areas. The effect is achieved as a result of the low statistical correlation between the original ACEs of participating BAs. A rule-based ADI approach has already been put into practice in the US Western Interconnection. The degree of actual ACE sharing is artificially limited because of the unknown redistribution of power flows and possible system congestion (these factors are not monitored in the existing ADI). This paper proposes a two-step linear programming (LP) ADI approach that incorporates congestion constraints. In the first step of the proposed LP ADI, the line transmission limits are enforced by setting up corresponding constraints. In the second step, the business fairness is pursued. Simulation is performed to compare the properties of the proposed LP ADI and the existing rule-based ADI. Favorable features, such as avoiding line limit violations and increasing the degree of possible ACE sharing, are observed for the proposed LP ADI.

  5. Application of parameter estimation to aircraft stability and control: The output-error approach

    NASA Technical Reports Server (NTRS)

    Maine, Richard E.; Iliff, Kenneth W.

    1986-01-01

    The practical application of parameter estimation methodology to the problem of estimating aircraft stability and control derivatives from flight test data is examined. The primary purpose of the document is to present a comprehensive and unified picture of the entire parameter estimation process and its integration into a flight test program. The document concentrates on the output-error method to provide a focus for detailed examination and to allow us to give specific examples of situations that have arisen. The document first derives the aircraft equations of motion in a form suitable for application to estimation of stability and control derivatives. It then discusses the issues that arise in adapting the equations to the limitations of analysis programs, using a specific program for an example. The roles and issues relating to mass distribution data, preflight predictions, maneuver design, flight scheduling, instrumentation sensors, data acquisition systems, and data processing are then addressed. Finally, the document discusses evaluation and the use of the analysis results.

  6. Control of bootstrap current in the pedestal region of tokamaks

    SciTech Connect

    Shaing, K. C.; Lai, A. L.

    2013-12-15

    The high confinement mode (H-mode) plasmas in the pedestal region of tokamaks are characterized by steep gradient of the radial electric field, and sonic poloidal U{sub p,m} flow that consists of poloidal components of the E×B flow and the plasma flow velocity that is parallel to the magnetic field B. Here, E is the electric field. The bootstrap current that is important for the equilibrium, and stability of the pedestal of H-mode plasmas is shown to have an expression different from that in the conventional theory. In the limit where ‖U{sub p,m}‖≫ 1, the bootstrap current is driven by the electron temperature gradient and inductive electric field fundamentally different from that in the conventional theory. The bootstrap current in the pedestal region can be controlled through manipulating U{sub p,m} and the gradient of the radial electric. This, in turn, can control plasma stability such as edge-localized modes. Quantitative evaluations of various coefficients are shown to illustrate that the bootstrap current remains finite when ‖U{sub p,m}‖ approaches infinite and to provide indications how to control the bootstrap current. Approximate analytic expressions for viscous coefficients that join results in the banana and plateau-Pfirsch-Schluter regimes are presented to facilitate bootstrap and neoclassical transport simulations in the pedestal region.

  7. 13. VIEW OF CONTROL CONSOLE CURRENTLY USED ON OCCASION FOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. VIEW OF CONTROL CONSOLE CURRENTLY USED ON OCCASION FOR AMATUER RADIO AND TO PERIODICALLY ACTIVE STATION KPS. NOTE CLOCK ON WALL. SHADED PORTIONS ON 24HR CLOCK (15-18 AND 45-48 MINUTES) INDICATED MINUTES EACH HOUR WHEN STATIONS WOULD NOT TRANSMIT AND LISTEN FOR WEAK DISTRESS SIGNALS. - Marconi Radio Sites, Receiving, Point Reyes Station, Marin County, CA

  8. Central Neural Control of the Cardiovascular System: Current Perspectives

    ERIC Educational Resources Information Center

    Dampney, Roger A. L.

    2016-01-01

    This brief review, which is based on a lecture presented at the American Physiological Society Teaching Refresher Course on the Brain and Systems Control as part of the Experimental Biology meeting in 2015, aims to summarize current concepts of the principal mechanisms in the brain that regulate the autonomic outflow to the cardiovascular system.…

  9. Central Neural Control of the Cardiovascular System: Current Perspectives

    ERIC Educational Resources Information Center

    Dampney, Roger A. L.

    2016-01-01

    This brief review, which is based on a lecture presented at the American Physiological Society Teaching Refresher Course on the Brain and Systems Control as part of the Experimental Biology meeting in 2015, aims to summarize current concepts of the principal mechanisms in the brain that regulate the autonomic outflow to the cardiovascular system.…

  10. Basic mechanisms controlling the sweeping efficiency of propagating current sheets

    NASA Astrophysics Data System (ADS)

    Berkery, J. W.; Choueiri, E. Y.

    2006-02-01

    The basic mechanisms controlling the sweeping efficiency of propagating current sheets are investigated through experiments and analytical modelling. The sweeping efficiency of a current sheet in a parallel plate gas-fed pulsed plasma accelerator is defined as the ratio of the current sheet mass to the total available propellant mass. Permeability of neutrals through the sheet, and leakage of mass out of the sheet and into a cathode wake, decrease the sweeping efficiency. The sweeping efficiency of current sheets in argon, neon, helium and hydrogen propellants at different initial pressures was determined through measurements of sheet velocity with high speed photography and of sheet mass with laser interferometry. The mechanism that controls the sweeping efficiency of propagating current sheets was found to be an interplay of two processes: the flux of mass entering the sheet and the leakage of mass at the cathode, with the former dependent on the degree of permeability and the latter dependent on the level of ion current as determined by the ion Hall parameter.

  11. Spin-torque switching and control using chirped AC currents

    NASA Astrophysics Data System (ADS)

    Klughertz, Guillaume; Friedland, Lazar; Hervieux, Paul-Antoine; Manfredi, Giovanni

    2017-10-01

    We propose to use oscillating spin currents with slowly varying frequency (chirp) to manipulate and control the magnetization dynamics in a nanomagnet. By recasting the Landau–Lifshitz–Slonczewski equation in a quantum-like two-level formalism, we show that a chirped spin current polarized in the direction normal to the anisotropy axis can induce a stable precession of the magnetic moment at any angle (up to 90^\\circ ) with respect to the anisotropy axis. The drive current can be modest (10^6~A~cm-2 or lower) provided the chirp rate is sufficiently slow. The induced precession is stable against thermal noise, even for small nano-objects at room temperature. Complete reversal of the magnetization can be achieved by adding a small external magnetic field antiparallel to the easy axis. Alternatively, a combination of chirped ac and dc currents with different polarization directions can also be used to trigger the reversal.

  12. Development of a current-controlled defibrillator for clinical tests.

    PubMed

    Fischer, M; Schönegg, M; Schöchlin, J; Bolz, A

    2002-01-01

    The work presented here is only a part of the development for a new current-controlled defibrillator. In the diploma thesis "Development and construction of a current-controlled defibrillator for clinical tests" the most important part was the control and safety of the defibrillator. To ensure a safe circuit design, a risk-analysis and a Failure Mode and Effects Analysis (FMEA) were necessary. Another major part was the programming of a microcontroller in embedded C and a programmable logic device in Very High Speed Integrated Circuit Description Language (VHDL). The circuit had to be constructed, and the defibrillator was optically decoupled from the laptop for safety reasons. The waveform-data can be transmitted to the microcontroller from the laptop, and the logged data is then transmitted back.

  13. Differential voltage current controlled current conveyor with low-voltage operation capability

    NASA Astrophysics Data System (ADS)

    Laoudias, C.; Psychalinos, C.

    2014-07-01

    A novel differential voltage current controlled current conveyor topology is introduced in this article. It has the capability for operating in a low-voltage power supply environment and, also, offers resistorless filter realisations. The main attractive offered benefit is that the handling of AC signals is exclusively performed by nMOS transistors and, thus, the proposed element has capability for high-frequency operation. The performance of the proposed cell has been experimentally verified through the realisation of two 3rd-order filters, derived according to the leapfrog and component substitution methods. The filter topologies have been fabricated through the AMS 0.35 µm CMOS process.

  14. Current control of PMSM based on maximum torque control reference frame

    NASA Astrophysics Data System (ADS)

    Ohnuma, Takumi

    2017-07-01

    This study presents a new method of current controls of PMSMs (Permanent Magnet Synchronous Motors) based on a maximum torque control reference frame, which is suitable for high-performance controls of the PMSMs. As the issues of environment and energy increase seriously, PMSMs, one of the AC motors, are becoming popular because of their high-efficiency and high-torque density in various applications, such as electric vehicles, trains, industrial machines, and home appliances. To use the PMSMs efficiently, a proper current control of the PMSMs is necessary. In general, a rotational coordinate system synchronizing with the rotor is used for the current control of PMSMs. In the rotating reference frame, the current control is easier because the currents on the rotating reference frame can be expressed as a direct current in the controller. On the other hand, the torque characteristics of PMSMs are non-linear and complex; the PMSMs are efficient and high-density though. Therefore, a complicated control system is required to involve the relation between the torque and the current, even though the rotating reference frame is adopted. The maximum torque control reference frame provides a simpler way to control efficiently the currents taking the torque characteristics of the PMSMs into consideration.

  15. An Efficient Silent Data Corruption Detection Method with Error-Feedback Control and Even Sampling for HPC Applications

    SciTech Connect

    Di, Sheng; Berrocal, Eduardo; Cappello, Franck

    2015-01-01

    The silent data corruption (SDC) problem is attracting more and more attentions because it is expected to have a great impact on exascale HPC applications. SDC faults are hazardous in that they pass unnoticed by hardware and can lead to wrong computation results. In this work, we formulate SDC detection as a runtime one-step-ahead prediction method, leveraging multiple linear prediction methods in order to improve the detection results. The contributions are twofold: (1) we propose an error feedback control model that can reduce the prediction errors for different linear prediction methods, and (2) we propose a spatial-data-based even-sampling method to minimize the detection overheads (including memory and computation cost). We implement our algorithms in the fault tolerance interface, a fault tolerance library with multiple checkpoint levels, such that users can conveniently protect their HPC applications against both SDC errors and fail-stop errors. We evaluate our approach by using large-scale traces from well-known, large-scale HPC applications, as well as by running those HPC applications on a real cluster environment. Experiments show that our error feedback control model can improve detection sensitivity by 34-189% for bit-flip memory errors injected with the bit positions in the range [20,30], without any degradation on detection accuracy. Furthermore, memory size can be reduced by 33% with our spatial-data even-sampling method, with only a slight and graceful degradation in the detection sensitivity.

  16. POWER-ENHANCED MULTIPLE DECISION FUNCTIONS CONTROLLING FAMILY-WISE ERROR AND FALSE DISCOVERY RATES

    PubMed Central

    Peña, Edsel A.; Habiger, Joshua D.; Wu, Wensong

    2014-01-01

    Improved procedures, in terms of smaller missed discovery rates (MDR), for performing multiple hypotheses testing with weak and strong control of the family-wise error rate (FWER) or the false discovery rate (FDR) are developed and studied. The improvement over existing procedures such as the Šidák procedure for FWER control and the Benjamini–Hochberg (BH) procedure for FDR control is achieved by exploiting possible differences in the powers of the individual tests. Results signal the need to take into account the powers of the individual tests and to have multiple hypotheses decision functions which are not limited to simply using the individual p-values, as is the case, for example, with the Šidák, Bonferroni, or BH procedures. They also enhance understanding of the role of the powers of individual tests, or more precisely the receiver operating characteristic (ROC) functions of decision processes, in the search for better multiple hypotheses testing procedures. A decision-theoretic framework is utilized, and through auxiliary randomizers the procedures could be used with discrete or mixed-type data or with rank-based nonparametric tests. This is in contrast to existing p-value based procedures whose theoretical validity is contingent on each of these p-value statistics being stochastically equal to or greater than a standard uniform variable under the null hypothesis. Proposed procedures are relevant in the analysis of high-dimensional “large M, small n” data sets arising in the natural, physical, medical, economic and social sciences, whose generation and creation is accelerated by advances in high-throughput technology, notably, but not limited to, microarray technology. PMID:25018568

  17. Value-based HR practices, i-deals and clinical error control with CSR as a moderator.

    PubMed

    Luu, Tuan; Rowley, Chris; Siengthai, Sununta; Thanh Thao, Vo

    2017-05-08

    Purpose Notwithstanding the rising magnitude of system factors in patient safety improvement, "human factors" such as idiosyncratic deals (i-deals) which also contribute to the adjustment of system deficiencies should not be neglected. The purpose of this paper is to investigate the role of value-based HR practices in catalyzing i-deals, which then influence clinical error control. The research further examines the moderating role of corporate social responsibility (CSR) on the effect of value-based HR practices on i-deals. Design/methodology/approach The data were collected from middle-level clinicians from hospitals in the Vietnam context. Findings The research results confirmed the effect chain from value-based HR practices through i-deals to clinical error control with CSR as a moderator. Originality/value The HRM literature is expanded through enlisting i-deals and clinical error control as the outcomes of HR practices.

  18. The bridge-type fault current controller--a new facts controller

    SciTech Connect

    Boenig, Heinrich J.; Mielke, C. H.; Burley, B. L.; Chen, Hong; Waynert, J. A.; Willis, J. O.

    2002-01-01

    The operation of a novel current controller, which can also function as a fault current limiter and as a solid-state ac circuit breaker, is presented. The controller, which consists of a thyristor bridge, an inductor, and an optional bias power supply, is installed in series with the voltage source and the load, For load current values smaller than a preset value, the inductor of the current controller presents no impedance to the ac current flow. For values higher than the preset current value, the inductor is switched automatically into the ac circuit and limits the amount of current flow. Theoretical results in the form of circuit simulations and experimental results with a single-phase unit, operating on a 13.7 kV three-phase system with peak short-circuit currents of 3140 Arms, are presented.

  19. Geometrical control of pure spin current induced domain wall depinning

    NASA Astrophysics Data System (ADS)

    Pfeiffer, A.; Reeve, R. M.; Voto, M.; Savero-Torres, W.; Richter, N.; Vila, L.; Attané, J. P.; Lopez-Diaz, L.; Kläui, Mathias

    2017-03-01

    We investigate the pure spin-current assisted depinning of magnetic domain walls in half ring based Py/Al lateral spin valve structures. Our optimized geometry incorporating a patterned notch in the detector electrode, directly below the Al spin conduit, provides a tailored pinning potential for a transverse domain wall and allows for a precise control over the magnetization configuration and as a result the domain wall pinning. Due to the patterned notch, we are able to study the depinning field as a function of the applied external field for certain applied current densities and observe a clear asymmetry for the two opposite field directions. Micromagnetic simulations show that this can be explained by the asymmetry of the pinning potential. By direct comparison of the calculated efficiencies for different external field and spin current directions, we are able to disentangle the different contributions from the spin transfer torque, Joule heating and the Oersted field. The observed high efficiency of the pure spin current induced spin transfer torque allows for a complete depinning of the domain wall at zero external field for a charge current density of 6\\centerdot {{10}11} A m-2, which is attributed to the optimal control of the position of the domain wall.

  20. Smart monitoring system based on adaptive current control for superconducting cable test

    SciTech Connect

    Arpaia, Pasquale; Ballarino, Amalia; Montenero, Giuseppe; Daponte, Vincenzo; Svelto, Cesare

    2014-12-15

    A smart monitoring system for superconducting cable test is proposed with an adaptive current control of a superconducting transformer secondary. The design, based on Fuzzy Gain Scheduling, allows the controller parameters to adapt continuously, and finely, to the working variations arising from transformer nonlinear dynamics. The control system is integrated in a fully digital control loop, with all the related benefits, i.e., high noise rejection, ease of implementation/modification, and so on. In particular, an accurate model of the system, controlled by a Fuzzy Gain Scheduler of the superconducting transformer, was achieved by an experimental campaign through the working domain at several current ramp rates. The model performance was characterized by simulation, under all the main operating conditions, in order to guide the controller design. Finally, the proposed monitoring system was experimentally validated at European Organization for Nuclear Research (CERN) in comparison to the state-of-the-art control system [P. Arpaia, L. Bottura, G. Montenero, and S. Le Naour, “Performance improvement of a measurement station for superconducting cable test,” Rev. Sci. Instrum.83, 095111 (2012)] of the Facility for the Research on Superconducting Cables, achieving a significant performance improvement: a reduction in the system overshoot by 50%, with a related attenuation of the corresponding dynamic residual error (both absolute and RMS) up to 52%.

  1. Smart monitoring system based on adaptive current control for superconducting cable test

    NASA Astrophysics Data System (ADS)

    Arpaia, Pasquale; Ballarino, Amalia; Daponte, Vincenzo; Montenero, Giuseppe; Svelto, Cesare

    2014-12-01

    A smart monitoring system for superconducting cable test is proposed with an adaptive current control of a superconducting transformer secondary. The design, based on Fuzzy Gain Scheduling, allows the controller parameters to adapt continuously, and finely, to the working variations arising from transformer nonlinear dynamics. The control system is integrated in a fully digital control loop, with all the related benefits, i.e., high noise rejection, ease of implementation/modification, and so on. In particular, an accurate model of the system, controlled by a Fuzzy Gain Scheduler of the superconducting transformer, was achieved by an experimental campaign through the working domain at several current ramp rates. The model performance was characterized by simulation, under all the main operating conditions, in order to guide the controller design. Finally, the proposed monitoring system was experimentally validated at European Organization for Nuclear Research (CERN) in comparison to the state-of-the-art control system [P. Arpaia, L. Bottura, G. Montenero, and S. Le Naour, "Performance improvement of a measurement station for superconducting cable test," Rev. Sci. Instrum. 83, 095111 (2012)] of the Facility for the Research on Superconducting Cables, achieving a significant performance improvement: a reduction in the system overshoot by 50%, with a related attenuation of the corresponding dynamic residual error (both absolute and RMS) up to 52%.

  2. Technology-induced errors. The current use of frameworks and models from the biomedical and life sciences literatures.

    PubMed

    Borycki, E M; Kushniruk, A W; Bellwood, P; Brender, J

    2012-01-01

    The objective of this paper is to examine the extent, range and scope to which frameworks, models and theories dealing with technology-induced error have arisen in the biomedical and life sciences literature as indexed by Medline®. To better understand the state of work in the area of technology-induced error involving frameworks, models and theories, the authors conducted a search of Medline® using selected key words identified from seminal articles in this research area. Articles were reviewed and those pertaining to frameworks, models or theories dealing with technology-induced error were further reviewed by two researchers. All articles from Medline® from its inception to April of 2011 were searched using the above outlined strategy. 239 citations were returned. Each of the abstracts for the 239 citations were reviewed by two researchers. Eleven articles met the criteria based on abstract review. These 11 articles were downloaded for further in-depth review. The majority of the articles obtained describe frameworks and models with reference to theories developed in other literatures outside of healthcare. The papers were grouped into several areas. It was found that articles drew mainly from three literatures: 1) the human factors literature (including human-computer interaction and cognition), 2) the organizational behavior/sociotechnical literature, and 3) the software engineering literature. A variety of frameworks and models were found in the biomedical and life sciences literatures. These frameworks and models drew upon and extended frameworks, models and theoretical perspectives that have emerged in other literatures. These frameworks and models are informing an emerging line of research in health and biomedical informatics involving technology-induced errors in healthcare.

  3. Control of the current density profile with lower hybrid current drive on PBX-M

    SciTech Connect

    Bell, R.E.; Bernabei, S.; Chu, T.K.; Gettelfinger, G.; Greenough, N.; Hatcher, R.; Ignat, D.; Jardin, S.; Kaita, R.; Kaye, S.; Kozub, T.; Kugel, H.; LeBlanc, B.; Okabayashi, M.; Paul, S.; Sauthoff, N.; Sesnic, S.; Sun, Y.; Takahashi, H.; Tighe, W.; Valeo, E.; von Goeler, S.; Blush, L.; Doerner, R.; Schmitz, L.; Tynan, G.; Dunlap, J.; England, A.; Harris, J.; Hirshman, S.; Isler, R.; Lee, D.; Jones, S.; Kesner, J.; Luckhardt, S.; Paoletti, F.; Levinton, F.; Timini, F.

    1993-07-01

    Lower hybrid current drive (LHCD) is being explored as a means to control the current density profile on PBX-M with the goal of raising the central safety factor q(O) to values of 1.5-2 to facilitate access to a full-volume second stable regime. Initial experiments have been conducted with up to 400 kW of 4.6 GHz LH power in circular and indented plasmas with modest parameters. A tangential-viewing two-dimensional hard x-ray imaging diagnostic has been used to observe the bremsstrahlung emission from the suprathermal electrons generated during LHCD. Hollow hard x-ray images have indicated off-axis localization of the driven current. A serious obstacle to the control of the current density profile with LHCD is the concomitant generation of MHD activity, which can seriously degrade the confinement of suprathermal electrons. By combining neutral beam injection with LHCD, an MHD-free condition has been obtained where q(O) is raised above 1.

  4. Composite Interval Mapping Based on Lattice Design for Error Control May Increase Power of Quantitative Trait Locus Detection

    PubMed Central

    Huang, Zhongwen; Zhao, Tuanjie; Xing, Guangnan; Gai, Junyi; Guan, Rongzhan

    2015-01-01

    Experimental error control is very important in quantitative trait locus (QTL) mapping. Although numerous statistical methods have been developed for QTL mapping, a QTL detection model based on an appropriate experimental design that emphasizes error control has not been developed. Lattice design is very suitable for experiments with large sample sizes, which is usually required for accurate mapping of quantitative traits. However, the lack of a QTL mapping method based on lattice design dictates that the arithmetic mean or adjusted mean of each line of observations in the lattice design had to be used as a response variable, resulting in low QTL detection power. As an improvement, we developed a QTL mapping method termed composite interval mapping based on lattice design (CIMLD). In the lattice design, experimental errors are decomposed into random errors and block-within-replication errors. Four levels of block-within-replication errors were simulated to show the power of QTL detection under different error controls. The simulation results showed that the arithmetic mean method, which is equivalent to a method under random complete block design (RCBD), was very sensitive to the size of the block variance and with the increase of block variance, the power of QTL detection decreased from 51.3% to 9.4%. In contrast to the RCBD method, the power of CIMLD and the adjusted mean method did not change for different block variances. The CIMLD method showed 1.2- to 7.6-fold higher power of QTL detection than the arithmetic or adjusted mean methods. Our proposed method was applied to real soybean (Glycine max) data as an example and 10 QTLs for biomass were identified that explained 65.87% of the phenotypic variation, while only three and two QTLs were identified by arithmetic and adjusted mean methods, respectively. PMID:26076140

  5. Integration of auditory and somatosensory error signals in the neural control of speech movements

    PubMed Central

    Feng, Yongqiang; Gracco, Vincent L.

    2011-01-01

    We investigated auditory and somatosensory feedback contributions to the neural control of speech. In task I, sensorimotor adaptation was studied by perturbing one of these sensory modalities or both modalities simultaneously. The first formant (F1) frequency in the auditory feedback was shifted up by a real-time processor and/or the extent of jaw opening was increased or decreased with a force field applied by a robotic device. All eight subjects lowered F1 to compensate for the up-shifted F1 in the feedback signal regardless of whether or not the jaw was perturbed. Adaptive changes in subjects' acoustic output resulted from adjustments in articulatory movements of the jaw or tongue. Adaptation in jaw opening extent in response to the mechanical perturbation occurred only when no auditory feedback perturbation was applied or when the direction of adaptation to the force was compatible with the direction of adaptation to a simultaneous acoustic perturbation. In tasks II and III, subjects' auditory and somatosensory precision and accuracy were estimated. Correlation analyses showed that the relationships 1) between F1 adaptation extent and auditory acuity for F1 and 2) between jaw position adaptation extent and somatosensory acuity for jaw position were weak and statistically not significant. Taken together, the combined findings from this work suggest that, in speech production, sensorimotor adaptation updates the underlying control mechanisms in such a way that the planning of vowel-related articulatory movements takes into account a complex integration of error signals from previous trials but likely with a dominant role for the auditory modality. PMID:21562187

  6. Integration of auditory and somatosensory error signals in the neural control of speech movements.

    PubMed

    Feng, Yongqiang; Gracco, Vincent L; Max, Ludo

    2011-08-01

    We investigated auditory and somatosensory feedback contributions to the neural control of speech. In task I, sensorimotor adaptation was studied by perturbing one of these sensory modalities or both modalities simultaneously. The first formant (F1) frequency in the auditory feedback was shifted up by a real-time processor and/or the extent of jaw opening was increased or decreased with a force field applied by a robotic device. All eight subjects lowered F1 to compensate for the up-shifted F1 in the feedback signal regardless of whether or not the jaw was perturbed. Adaptive changes in subjects' acoustic output resulted from adjustments in articulatory movements of the jaw or tongue. Adaptation in jaw opening extent in response to the mechanical perturbation occurred only when no auditory feedback perturbation was applied or when the direction of adaptation to the force was compatible with the direction of adaptation to a simultaneous acoustic perturbation. In tasks II and III, subjects' auditory and somatosensory precision and accuracy were estimated. Correlation analyses showed that the relationships 1) between F1 adaptation extent and auditory acuity for F1 and 2) between jaw position adaptation extent and somatosensory acuity for jaw position were weak and statistically not significant. Taken together, the combined findings from this work suggest that, in speech production, sensorimotor adaptation updates the underlying control mechanisms in such a way that the planning of vowel-related articulatory movements takes into account a complex integration of error signals from previous trials but likely with a dominant role for the auditory modality.

  7. Myoelectric hand prosthesis force control through servo motor current feedback.

    PubMed

    Sono, Tálita Saemi Payossim; Menegaldo, Luciano Luporini

    2009-10-01

    This paper presents the prehension force closed-loop control design of a mechanical finger commanded by electromyographic signal (EMG) from a patient's arm. The control scheme was implemented and tested in a mechanical finger prototype with three degrees of freedom and one actuator, driven by arm muscles EMG of normal volunteers. Real-time indirect estimation of prehension force was assessed by measuring the DC servo motor actuator current. A model of the plant comprising finger, motor, and grasped object was proposed. Model parameters were identified experimentally and a classical feedback phase-lead compensator was designed. The controlled mechanical finger was able to provide a more accurate prehension force modulation of a compliant object when compared to open-loop control.

  8. Current good manufacturing practice in manufacturing, processing, packing, or holding of drugs; revision of certain labeling controls. Final rule.

    PubMed

    2012-03-20

    The Food and Drug Administration (FDA) is amending the packaging and labeling control provisions of the current good manufacturing practice (CGMP) regulations for human and veterinary drug products by limiting the application of special control procedures for the use of cut labeling to immediate container labels, individual unit cartons, or multiunit cartons containing immediate containers that are not packaged in individual unit cartons. FDA is also permitting the use of any automated technique, including differentiation by labeling size and shape, that physically prevents incorrect labeling from being processed by labeling and packaging equipment when cut labeling is used. This action is intended to protect consumers from labeling errors more likely to cause adverse health consequences, while eliminating the regulatory burden of applying the rule to labeling unlikely to reach or adversely affect consumers. This action is also intended to permit manufacturers to use a broader range of error prevention and labeling control techniques than permitted by current CGMPs.

  9. Electric Machine with Boosted Inductance to Stabilize Current Control

    NASA Technical Reports Server (NTRS)

    Abel, Steve

    2013-01-01

    High-powered motors typically have very low resistance and inductance (R and L) in their windings. This makes the pulse-width modulated (PWM) control of the current very difficult, especially when the bus voltage (V) is high. These R and L values are dictated by the motor size, torque (Kt), and back-emf (Kb) constants. These constants are in turn set by the voltage and the actuation torque-speed requirements. This problem is often addressed by placing inductive chokes within the controller. This approach is undesirable in that space is taken and heat is added to the controller. By keeping the same motor frame, reducing the wire size, and placing a correspondingly larger number of turns in each slot, the resistance, inductance, torque constant, and back-emf constant are all increased. The increased inductance aids the current control but ruins the Kt and Kb selections. If, however, a fraction of the turns is moved from their "correct slot" to an "incorrect slot," the increased R and L values are retained, but the Kt and Kb values are restored to the desired values. This approach assumes that increased resistance is acceptable to a degree. In effect, the heat allocated to the added inductance has been moved from the controller to the motor body, which in some cases is preferred.

  10. Prevention and control of schistosomiasis: a current perspective

    PubMed Central

    Inobaya, Marianette T; Olveda, Remigio M; Chau, Thao NP; Olveda, David U; Ross, Allen GP

    2014-01-01

    Schistosomiasis is a neglected tropical disease that ranks second only to malaria in terms of human suffering in the tropics and subtropics. Five species are known to infect man and there are currently over 240 million people infected worldwide. The cornerstone of control to date has been mass drug administration with 40 mg/kg of praziquantel but there are problems with this approach. Human and bovine vaccines are in various stages of development. Integrated control, targeting the life cycle, is the only approach that will lead to sustainability and future elimination. PMID:25400499

  11. A control-oriented model of the current profile in tokamak plasma

    NASA Astrophysics Data System (ADS)

    Witrant, E.; Joffrin, E.; Brémond, S.; Giruzzi, G.; Mazon, D.; Barana, O.; Moreau, P.

    2007-07-01

    This paper proposes a control-oriented approach to the tokamak plasma current profile dynamics. It is established based on a consistent set of simplified relationships, in particular for the microwave current drive sources, rather than exact physical modelling. Assuming that a proper model for advanced control schemes can be established using the so-called cylindrical approximation and neglecting the diamagnetic effects, we propose a model that focuses on the flux diffusion (from which the current profile is inferred). Its inputs are some real-time measurements available on modern tokamaks and the effects of some major actuators, such as the magnetic coils, lower hybrid (LHCD), electron and ion cyclotron frequency (ECCD and ICRH) systems, are particularly taken into account. More precisely, the non-inductive current profile sources are modelled as 3-parameters functions of the control inputs derived either from approximate theoretical formulae for the ECCD and bootstrap terms or from experimental scaling laws specifically developed from hard x-ray Tore Supra data for the LHCD influence. The use of scaling laws in this model reflects the fact that the operation of future reactors will certainly depend upon a great number of scaling laws and specific engineering parameters. The discretization issues are also specifically addressed, to ensure robustness with respect to discretisation errors and the efficiency (in terms of computation time) of the associated algorithm. This model is compared with experimental results and the CRONOS solver for tore supra tokamak.

  12. Reversible control of current across lipid membranes by local heating

    PubMed Central

    Urban, Patrick; Kirchner, Silke R.; Mühlbauer, Christian; Lohmüller, Theobald; Feldmann, Jochen

    2016-01-01

    Lipid membranes are almost impermeable for charged molecules and ions that can pass the membrane barrier only with the help of specialized transport proteins. Here, we report how temperature manipulation at the nanoscale can be employed to reversibly control the electrical resistance and the amount of current that flows through a bilayer membrane with pA resolution. For this experiment, heating is achieved by irradiating gold nanoparticles that are attached to the bilayer membrane with laser light at their plasmon resonance frequency. We found that controlling the temperature on the nanoscale renders it possible to reproducibly regulate the current across a phospholipid membrane and the membrane of living cells in absence of any ion channels. PMID:26940847

  13. FLEXIBLE CONTROL OF DENSITY CURRENT MIGRATION BY USING SLUICE GATE

    NASA Astrophysics Data System (ADS)

    Akahori, Ryosuke; Yoshikawa, Yasuhiro; Yasuda, Hiroyasu

    Controlling adverse density currents has been an important issue on water quality and ecosystems of brackish water regions. This study proposes to apply sluice gate for flexible control of density current migration in open channels. Hydraulic characteristics of density flows around a sluice gate are investigated by flume experiments employing the Particle Image Velocimetry technique and numerical calculations by a Large Eddy Simulation model. The results show that the behavior of density front migration under a sluice gate is dominated by internal Froude number of both fresh water and salt water layers, and entrainment of salt water in a downstream region of a dike is influenced by evolution of instantaneous flow structures in a fresh water layer.

  14. Reversible control of current across lipid membranes by local heating

    NASA Astrophysics Data System (ADS)

    Urban, Patrick; Kirchner, Silke R.; Mühlbauer, Christian; Lohmüller, Theobald; Feldmann, Jochen

    2016-03-01

    Lipid membranes are almost impermeable for charged molecules and ions that can pass the membrane barrier only with the help of specialized transport proteins. Here, we report how temperature manipulation at the nanoscale can be employed to reversibly control the electrical resistance and the amount of current that flows through a bilayer membrane with pA resolution. For this experiment, heating is achieved by irradiating gold nanoparticles that are attached to the bilayer membrane with laser light at their plasmon resonance frequency. We found that controlling the temperature on the nanoscale renders it possible to reproducibly regulate the current across a phospholipid membrane and the membrane of living cells in absence of any ion channels.

  15. Reversible control of current across lipid membranes by local heating.

    PubMed

    Urban, Patrick; Kirchner, Silke R; Mühlbauer, Christian; Lohmüller, Theobald; Feldmann, Jochen

    2016-03-04

    Lipid membranes are almost impermeable for charged molecules and ions that can pass the membrane barrier only with the help of specialized transport proteins. Here, we report how temperature manipulation at the nanoscale can be employed to reversibly control the electrical resistance and the amount of current that flows through a bilayer membrane with pA resolution. For this experiment, heating is achieved by irradiating gold nanoparticles that are attached to the bilayer membrane with laser light at their plasmon resonance frequency. We found that controlling the temperature on the nanoscale renders it possible to reproducibly regulate the current across a phospholipid membrane and the membrane of living cells in absence of any ion channels.

  16. Proprioceptive control of wrist movements in Parkinson's disease. Reduced muscle vibration-induced errors.

    PubMed

    Rickards, C; Cody, F W

    1997-06-01

    The effects upon the trajectories of practised slow (approximately 9 degrees/s) voluntary wrist-extension movements of applying vibration to the tendon of an antagonist muscle (flexor carpi radialis) during the course of the movement have been studied in patients with idiopathic Parkinson's disease and age-matched healthy individuals. In both patient and control groups, flexor vibration elicited undershooting of wrist-extension movements. Wrist extensor and flexor surface EMG recordings indicated that, in patients and controls, such undershooting resulted principally from sustained reductions in extensor (prime mover) activity. Small vibration reflexes were commonly elicited in the wrist flexors which, in both Parkinson's disease and healthy subjects, were usually otherwise virtually quiescent during these slow extension movements. The amplitudes of such vibration reflexes did not differ systematically between patient and control groups and appeared inadequate to have exerted an appreciable braking action upon the extension trajectories. However, the extent of vibration-induced undershooting was, on average, significantly less in the Parkinson's disease group. In a subgroup of patients with asymmetrical parkinsonism the effects of antagonist vibration upon wrist movements of the more and less affected limb were compared. The degree of vibration-induced undershooting was significantly smaller on the more affected side. This finding suggests that disturbed proprioceptive guidance of voluntary movements in Parkinson's disease is related to the severity of clinical motor deficits. A small number Parkinson's disease patients were studied 'ON' and 'OFF' their routine anti-parkinsonian medication. A non-significant tendency was found for vibration-induced errors to be less marked in the 'OFF' state. In a separate series of experiments, under isometric conditions, vibration-induced EMG changes were recorded whilst subjects attempted to maintain a steady (15% maximum

  17. Stray current control in rehabilitating rail transit facilities

    SciTech Connect

    Fitzgerald, J.H. III; Bosma, R.; Paladines, F.

    1999-05-01

    An old Chicago direct current electrified railway yard and shop are being rehabilitated. Modern stray current control techniques are being introduced. Efficient rail operation and safety for the public and operating personnel are paramount. Metra is Chicago's commuter railroad, serving six counties in the metropolitan area. The Electric District, which was electrified in 1926, is a heavy rail system from downtown, serving the south side and suburbs. Operating on the same tracks from Randolph St., to Kensington is America's last electric interurban line, the Chicago South Shore and South Bend Railroad. All trains operate on 1,500-V direct current (DC) propulsion from an overhead catenary system, with the running rails as the negative return.

  18. Alterations in Neural Control of Constant Isometric Contraction with the Size of Error Feedback

    PubMed Central

    Hwang, Ing-Shiou; Lin, Yen-Ting; Huang, Wei-Min; Yang, Zong-Ru; Hu, Chia-Ling; Chen, Yi-Ching

    2017-01-01

    Discharge patterns from a population of motor units (MUs) were estimated with multi-channel surface electromyogram and signal processing techniques to investigate parametric differences in low-frequency force fluctuations, MU discharges, and force-discharge relation during static force-tracking with varying sizes of execution error presented via visual feedback. Fourteen healthy adults produced isometric force at 10% of maximal voluntary contraction through index abduction under three visual conditions that scaled execution errors with different amplification factors. Error-augmentation feedback that used a high amplification factor (HAF) to potentiate visualized error size resulted in higher sample entropy, mean frequency, ratio of high-frequency components, and spectral dispersion of force fluctuations than those of error-reducing feedback using a low amplification factor (LAF). In the HAF condition, MUs with relatively high recruitment thresholds in the dorsal interosseous muscle exhibited a larger coefficient of variation for inter-spike intervals and a greater spectral peak of the pooled MU coherence at 13–35 Hz than did those in the LAF condition. Manipulation of the size of error feedback altered the force-discharge relation, which was characterized with non-linear approaches such as mutual information and cross sample entropy. The association of force fluctuations and global discharge trace decreased with increasing error amplification factor. Our findings provide direct neurophysiological evidence that favors motor training using error-augmentation feedback. Amplification of the visualized error size of visual feedback could enrich force gradation strategies during static force-tracking, pertaining to selective increases in the discharge variability of higher-threshold MUs that receive greater common oscillatory inputs in the β-band. PMID:28125658

  19. The effect of speaking rate on serial-order sound-level errors in normal healthy controls and persons with aphasia

    PubMed Central

    Fossett, Tepanta R. D.; McNeil, Malcolm R.; Pratt, Sheila R.; Tompkins, Connie A.; Shuster, Linda I.

    2015-01-01

    Background Although many speech errors can be generated at either a linguistic or motoric level of production, phonetically well-formed sound-level serial-order errors are generally assumed to result from disruption of phonologic encoding (PE) processes. An influential model of PE (Dell, 1986; Dell, Burger & Svec, 1997) predicts that speaking rate should affect the relative proportion of these serial-order sound errors (anticipations, perseverations, exchanges). These predictions have been extended to, and have special relevance for persons with aphasia (PWA) because of the increased frequency with which speech errors occur and because their localization within the functional linguistic architecture may help in diagnosis and treatment. Supporting evidence regarding the effect of speaking rate on phonological encoding has been provided by studies using young normal language (NL) speakers and computer simulations. Limited data exist for older NL users and no group data exist for PWA. Aims This study tested the phonologic encoding properties of Dell's model of speech production (Dell, 1986; Dell,et al., 1997), which predicts that increasing speaking rate affects the relative proportion of serial-order sound errors (i.e., anticipations, perseverations, and exchanges). Methods & Procedures The effects of speech rate on the error ratios of anticipation/exchange (AE), anticipation/perseveration (AP) and vocal reaction time (VRT) were examined in 16 normal healthy controls (NHC) and 16 PWA without concomitant motor speech disorders. The participants were recorded performing a phonologically challenging (tongue twister) speech production task at their typical and two faster speaking rates. Outcomes & Results A significant effect of increased rate was obtained for the AP but not the AE ratio. Significant effects of group and rate were obtained for VRT. Conclusion Although the significant effect of rate for the AP ratio provided evidence that changes in speaking rate did

  20. The effect of speaking rate on serial-order sound-level errors in normal healthy controls and persons with aphasia.

    PubMed

    Fossett, Tepanta R D; McNeil, Malcolm R; Pratt, Sheila R; Tompkins, Connie A; Shuster, Linda I

    Although many speech errors can be generated at either a linguistic or motoric level of production, phonetically well-formed sound-level serial-order errors are generally assumed to result from disruption of phonologic encoding (PE) processes. An influential model of PE (Dell, 1986; Dell, Burger & Svec, 1997) predicts that speaking rate should affect the relative proportion of these serial-order sound errors (anticipations, perseverations, exchanges). These predictions have been extended to, and have special relevance for persons with aphasia (PWA) because of the increased frequency with which speech errors occur and because their localization within the functional linguistic architecture may help in diagnosis and treatment. Supporting evidence regarding the effect of speaking rate on phonological encoding has been provided by studies using young normal language (NL) speakers and computer simulations. Limited data exist for older NL users and no group data exist for PWA. This study tested the phonologic encoding properties of Dell's model of speech production (Dell, 1986; Dell,et al., 1997), which predicts that increasing speaking rate affects the relative proportion of serial-order sound errors (i.e., anticipations, perseverations, and exchanges). The effects of speech rate on the error ratios of anticipation/exchange (AE), anticipation/perseveration (AP) and vocal reaction time (VRT) were examined in 16 normal healthy controls (NHC) and 16 PWA without concomitant motor speech disorders. The participants were recorded performing a phonologically challenging (tongue twister) speech production task at their typical and two faster speaking rates. A significant effect of increased rate was obtained for the AP but not the AE ratio. Significant effects of group and rate were obtained for VRT. Although the significant effect of rate for the AP ratio provided evidence that changes in speaking rate did affect PE, the results failed to support the model derived predictions

  1. Evaluating the impact of sequencing error correction for RNA-seq data with ERCC RNA spike-in controls.

    PubMed

    Tong, Li; Yang, Cheng; Wu, Po-Yen; Wang, May D

    2016-02-01

    Sequencing errors are a major issue for several next-generation sequencing-based applications such as de novo assembly and single nucleotide polymorphism detection. Several error-correction methods have been developed to improve raw data quality. However, error-correction performance is hard to evaluate because of the lack of a ground truth. In this study, we propose a novel approach which using ERCC RNA spike-in controls as the ground truth to facilitate error-correction performance evaluation. After aligning raw and corrected RNA-seq data, we characterized the quality of reads by three metrics: mismatch patterns (i.e., the substitution rate of A to C) of reads aligned with one mismatch, mismatch patterns of reads aligned with two mismatches and the percentage increase of reads aligned to reference. We observed that the mismatch patterns for reads aligned with one mismatch are significantly correlated between ERCC spike-ins and real RNA samples. Based on such observations, we conclude that ERCC spike-ins can serve as ground truths for error correction beyond their previous applications for validation of dynamic range and fold-change response. Also, the mismatch patterns for ERCC reads aligned with one mismatch can serve as a novel and reliable metric to evaluate the performance of error-correction tools.

  2. Parallel Transmission Pulse Design with Explicit Control for the Specific Absorption Rate in the Presence of Radiofrequency Errors

    PubMed Central

    Martin, Adrian; Schiavi, Emanuele; Eryaman, Yigitcan; Herraiz, Joaquin L.; Gagoski, Borjan; Adalsteinsson, Elfar; Wald, Lawrence L.; Guerin, Bastien

    2016-01-01

    Purpose A new framework for the design of parallel transmit (pTx) pulses is presented introducing constraints for local and global specific absorption rate (SAR) in the presence of errors in the radiofrequency (RF) transmit chain. Methods The first step is the design of a pTx RF pulse with explicit constraints for global and local SAR. Then, the worst possible SAR associated with that pulse due to RF transmission errors (“worst-case SAR”) is calculated. Finally, this information is used to re-calculate the pulse with lower SAR constraints, iterating this procedure until its worst-case SAR is within safety limits. Results Analysis of an actual pTx RF transmit chain revealed amplitude errors as high as 8% (20%) and phase errors above 3° (15°) for spokes (spiral) pulses. Simulations show that using the proposed framework, pulses can be designed with controlled “worst-case SAR” in the presence of errors of this magnitude at minor cost of the excitation profile quality. Conclusion Our worst-case SAR-constrained pTx design strategy yields pulses with local and global SAR within the safety limits even in the presence of RF transmission errors. This strategy is a natural way to incorporate SAR safety factors in the design of pTx pulses. PMID:26147916

  3. A new assessment method of pHEMT models by comparing relative errors of drain current and its derivatives up to the third order

    NASA Astrophysics Data System (ADS)

    Dobeš, Josef; Grábner, Martin; Puričer, Pavel; Vejražka, František; Míchal, Jan; Popp, Jakub

    2017-05-01

    Nowadays, there exist relatively precise pHEMT models available for computer-aided design, and they are frequently compared to each other. However, such comparisons are mostly based on absolute errors of drain-current equations and their derivatives. In the paper, a novel method is suggested based on relative root-mean-square errors of both drain current and its derivatives up to the third order. Moreover, the relative errors are subsequently relativized to the best model in each category to further clarify obtained accuracies of both drain current and its derivatives. Furthermore, one our older and two newly suggested models are also included in comparison with the traditionally precise Ahmed, TOM-2 and Materka ones. The assessment is performed using measured characteristics of a pHEMT operating up to 110 GHz. Finally, a usability of the proposed models including the higher-order derivatives is illustrated using s-parameters analysis and measurement at more operating points as well as computation and measurement of IP3 points of a low-noise amplifier of a multi-constellation satellite navigation receiver with ATF-54143 pHEMT.

  4. Tuberculosis control in prisons: current situation and research gaps.

    PubMed

    Dara, Masoud; Acosta, Colleen D; Melchers, Natalie V S Vinkeles; Al-Darraji, Haider A A; Chorgoliani, Dato; Reyes, Hernan; Centis, Rosella; Sotgiu, Giovanni; D'Ambrosio, Lia; Chadha, Sarabjit S; Migliori, Giovanni Battista

    2015-03-01

    Tuberculosis (TB) in penitentiary services (prisons) is a major challenge to TB control. This review article describes the challenges that prison systems encounter in TB control and provides solutions for the more efficient use of limited resources based on the three pillars of the post-2015 End TB Strategy. This paper also proposes research priorities for TB control in prisons based on current challenges. Articles (published up to 2011) included in a recent systematic review on TB control in prisons were further reviewed. In addition, relevant articles in English (published 1990 to May 2014) were identified by searching keywords in PubMed and Google Scholar. Article bibliographies and conference abstracts were also hand-searched. Despite being a serious cause of morbidity and mortality among incarcerated populations, many prison systems encounter a variety of challenges that hinder TB control. These include, but are not limited to, insufficient laboratory capacity and diagnostic tools, interrupted supply of medicines, weak integration between civilian and prison TB services, inadequate infection control measures, and low policy priority for prison healthcare. Governmental commitment, partnerships, and sustained financing are needed in order to facilitate improvements in TB control in prisons, which will translate to the wider community. Copyright © 2015 World Health Organization. Published by Elsevier Ltd.. All rights reserved.

  5. A Genetic Assay for Transcription Errors Reveals Multilayer Control of RNA Polymerase II Fidelity

    PubMed Central

    Irvin, Jordan D.; Kireeva, Maria L.; Gotte, Deanna R.; Shafer, Brenda K.; Huang, Ingold; Kashlev, Mikhail; Strathern, Jeffrey N.

    2014-01-01

    We developed a highly sensitive assay to detect transcription errors in vivo. The assay is based on suppression of a missense mutation in the active site tyrosine in the Cre recombinase. Because Cre acts as tetramer, background from translation errors are negligible. Functional Cre resulting from rare transcription errors that restore the tyrosine codon can be detected by Cre-dependent rearrangement of reporter genes. Hence, transient transcription errors are captured as stable genetic changes. We used this Cre-based reporter to screen for mutations of Saccharomyces cerevisiae RPB1 (RPO21) that increase the level of misincorporation during transcription. The mutations are in three domains of Rpb1, the trigger loop, the bridge helix, and in sites involved in binding to TFIIS. Biochemical characterization demonstrates that these variants have elevated misincorporation, and/or ability to extend mispaired bases, or defects in TFIIS mediated editing. PMID:25232834

  6. A genetic assay for transcription errors reveals multilayer control of RNA polymerase II fidelity.

    PubMed

    Irvin, Jordan D; Kireeva, Maria L; Gotte, Deanna R; Shafer, Brenda K; Huang, Ingold; Kashlev, Mikhail; Strathern, Jeffrey N

    2014-09-01

    We developed a highly sensitive assay to detect transcription errors in vivo. The assay is based on suppression of a missense mutation in the active site tyrosine in the Cre recombinase. Because Cre acts as tetramer, background from translation errors are negligible. Functional Cre resulting from rare transcription errors that restore the tyrosine codon can be detected by Cre-dependent rearrangement of reporter genes. Hence, transient transcription errors are captured as stable genetic changes. We used this Cre-based reporter to screen for mutations of Saccharomyces cerevisiae RPB1 (RPO21) that increase the level of misincorporation during transcription. The mutations are in three domains of Rpb1, the trigger loop, the bridge helix, and in sites involved in binding to TFIIS. Biochemical characterization demonstrates that these variants have elevated misincorporation, and/or ability to extend mispaired bases, or defects in TFIIS mediated editing.

  7. Paradigm Shifts in Voluntary Force Control and Motor Unit Behaviors with the Manipulated Size of Visual Error Perception.

    PubMed

    Chen, Yi-Ching; Lin, Yen-Ting; Chang, Gwo-Ching; Hwang, Ing-Shiou

    2017-01-01

    The detection of error information is an essential prerequisite of a feedback-based movement. This study investigated the differential behavior and neurophysiological mechanisms of a cyclic force-tracking task using error-reducing and error-enhancing feedback. The discharge patterns of a relatively large number of motor units (MUs) were assessed with custom-designed multi-channel surface electromyography following mathematical decomposition of the experimentally-measured signals. Force characteristics, force-discharge relation, and phase-locking cortical activities in the contralateral motor cortex to individual MUs were contrasted among the low (LSF), normal (NSF), and high scaling factor (HSF) conditions, in which the sizes of online execution errors were displayed with various amplification ratios. Along with a spectral shift of the force output toward a lower band, force output with a more phase-lead became less irregular, and tracking accuracy was worse in the LSF condition than in the HSF condition. The coherent discharge of high phasic (HP) MUs with the target signal was greater, and inter-spike intervals were larger, in the LSF condition than in the HSF condition. Force-tracking in the LSF condition manifested with stronger phase-locked EEG activity in the contralateral motor cortex to discharge of the (HP) MUs (LSF > NSF, HSF). The coherent discharge of the (HP) MUs during the cyclic force-tracking predominated the force-discharge relation, which increased inversely to the error scaling factor. In conclusion, the size of visualized error gates motor unit discharge, force-discharge relation, and the relative influences of the feedback and feedforward processes on force control. A smaller visualized error size favors voluntary force control using a feedforward process, in relation to a selective central modulation that enhance the coherent discharge of (HP) MUs.

  8. Paradigm Shifts in Voluntary Force Control and Motor Unit Behaviors with the Manipulated Size of Visual Error Perception

    PubMed Central

    Chen, Yi-Ching; Lin, Yen-Ting; Chang, Gwo-Ching; Hwang, Ing-Shiou

    2017-01-01

    The detection of error information is an essential prerequisite of a feedback-based movement. This study investigated the differential behavior and neurophysiological mechanisms of a cyclic force-tracking task using error-reducing and error-enhancing feedback. The discharge patterns of a relatively large number of motor units (MUs) were assessed with custom-designed multi-channel surface electromyography following mathematical decomposition of the experimentally-measured signals. Force characteristics, force-discharge relation, and phase-locking cortical activities in the contralateral motor cortex to individual MUs were contrasted among the low (LSF), normal (NSF), and high scaling factor (HSF) conditions, in which the sizes of online execution errors were displayed with various amplification ratios. Along with a spectral shift of the force output toward a lower band, force output with a more phase-lead became less irregular, and tracking accuracy was worse in the LSF condition than in the HSF condition. The coherent discharge of high phasic (HP) MUs with the target signal was greater, and inter-spike intervals were larger, in the LSF condition than in the HSF condition. Force-tracking in the LSF condition manifested with stronger phase-locked EEG activity in the contralateral motor cortex to discharge of the (HP) MUs (LSF > NSF, HSF). The coherent discharge of the (HP) MUs during the cyclic force-tracking predominated the force-discharge relation, which increased inversely to the error scaling factor. In conclusion, the size of visualized error gates motor unit discharge, force-discharge relation, and the relative influences of the feedback and feedforward processes on force control. A smaller visualized error size favors voluntary force control using a feedforward process, in relation to a selective central modulation that enhance the coherent discharge of (HP) MUs. PMID:28348530

  9. Dynamics and stabilization of peak current-mode controlled buck converter with constant current load

    NASA Astrophysics Data System (ADS)

    Leng, Min-Rui; Zhou, Guo-Hua; Zhang, Kai-Tun; Li, Zhen-Hua

    2015-10-01

    The discrete iterative map model of peak current-mode controlled buck converter with constant current load (CCL), containing the output voltage feedback and ramp compensation, is established in this paper. Based on this model the complex dynamics of this converter is investigated by analyzing bifurcation diagrams and the Lyapunov exponent spectrum. The effects of ramp compensation and output voltage feedback on the stability of the converter are investigated. Experimental results verify the simulation and theoretical analysis. The stability boundary and chaos boundary are obtained under the theoretical conditions of period-doubling bifurcation and border collision. It is found that there are four operation regions in the peak current-mode controlled buck converter with CCL due to period-doubling bifurcation and border-collision bifurcation. Research results indicate that ramp compensation can extend the stable operation range and transfer the operating mode, and output voltage feedback can eventually eliminate the coexisting fast-slow scale instability. Project supported by the National Natural Science Foundation of China (Grant No. 61371033), the Fok Ying-Tung Education Foundation for Young Teachers in the Higher Education Institutions of China (Grant No. 142027), the Sichuan Provincial Youth Science and Technology Fund, China (Grant Nos. 2014JQ0015 and 2013JQ0033), and the Fundamental Research Funds for the Central Universities, China (Grant No. SWJTU11CX029).

  10. [Preliminary Study on Error Control of Medical Devices Test Reports Based on the Analytic Hierarchy Process].

    PubMed

    Huang, Yanhong; Xu, Honglei; Tu, Rong; Zhang, Xu; Huang, Min

    2016-01-01

    In this paper, the common errors in medical devices test reports are classified and analyzed. And then the main 11 influence factors for these inspection report errors are summarized. The hierarchy model was also developed and verified by presentation data using MATLAB. The feasibility of comprehensive weights quantitative comparison has been analyzed by using the analytic hierarchy process. In the end, this paper porspects the further research direction.

  11. A Monte Carlo Investigation of Methods for Controlling Type I Errors with Specification Searches in Structural Equation Modeling.

    ERIC Educational Resources Information Center

    Green, Samuel B.; Thompson, Marilyn S.; Babyak, Michael A.

    1998-01-01

    Simulated data for factor analytic models is used in the evaluation of three methods for controlling Type I errors: (1) the standard approach that involves testing each parameter at the 0.05 level; (2) the Bonferroni approach; and (3) a simultaneous test procedure (STP). Advantages offered by the Bonferroni approach are discussed. (SLD)

  12. Method of alignment error control in free-form surface metrology with the tilted-wave-interferometer

    NASA Astrophysics Data System (ADS)

    Li, Jia; Shen, Hua; Zhu, Rihong

    2016-04-01

    Compared with conventional optical elements, free-form surface optical elements, as a kind of nonrotationally symmetrical shaped component, can provide more freedom in optical design, optimize the structure of the optical system, and improve its performance. However, the difficulties involved in the measurement of free-form elements restrict their manufacture and application. A tilted-wave-interferometer (TWI) can achieve high precision in free-form surface measurement, but it requires higher space attitude error control. We analyze the relation between the alignment error and the measurement error introduced by the misalignment in free-form surface metrology with TWI. The attitude control method in the rotation direction is proposed based on the moire fringe technique. Then, combining it with the five-dimensional space attitude control method of aspherical elements, we put forward an alignment error control process in measuring the free-form surface. An experiment of measuring a free-form surface using TWI shows the effectiveness of our method.

  13. Motor imagery, P300 and error-related EEG-based robot arm movement control for rehabilitation purpose.

    PubMed

    Bhattacharyya, Saugat; Konar, Amit; Tibarewala, D N

    2014-12-01

    The paper proposes a novel approach toward EEG-driven position control of a robot arm by utilizing motor imagery, P300 and error-related potentials (ErRP) to align the robot arm with desired target position. In the proposed scheme, the users generate motor imagery signals to control the motion of the robot arm. The P300 waveforms are detected when the user intends to stop the motion of the robot on reaching the goal position. The error potentials are employed as feedback response by the user. On detection of error the control system performs the necessary corrections on the robot arm. Here, an AdaBoost-Support Vector Machine (SVM) classifier is used to decode the 4-class motor imagery and an SVM is used to decode the presence of P300 and ErRP waveforms. The average steady-state error, peak overshoot and settling time obtained for our proposed approach is 0.045, 2.8% and 44 s, respectively, and the average rate of reaching the target is 95%. The results obtained for the proposed control scheme make it suitable for designs of prosthetics in rehabilitative applications.

  14. Cross-Language Intrusion Errors in Aging Bilinguals Reveal the Link Between Executive Control and Language Selection

    PubMed Central

    Gollan, Tamar H.; Sandoval, Tiffany; Salmon, David P.

    2013-01-01

    Bilinguals outperform monolinguals on measures of executive control, but it is not known how bilingualism introduces these advantages. To address this question, we investigated whether language-control failures increase with aging-related declines in executive control. Eighteen younger and 18 older Spanish-English bilinguals completed a verbal-fluency task, in which they produced words in 18 categories (9 in each language), and a flanker task. Performance on both tasks exhibited robust effects of aging, but cross-language and within-language errors on the verbal-fluency task differed in a number of ways. Within-language errors occurred relatively often and decreased with higher levels of education in both younger and older bilinguals. In contrast, cross-language intrusions (e.g., inadvertently saying an English word on a Spanish-language trial) were rarely produced, were not associated with education level, and were strongly associated with flanker-task errors in older but not younger bilinguals. These results imply that executive control plays a role in maintaining language selection, but they also suggest the presence of independent forces that prevent language-selection errors. PMID:21775653

  15. Doubly-Latent Models of School Contextual Effects: Integrating Multilevel and Structural Equation Approaches to Control Measurement and Sampling Error

    ERIC Educational Resources Information Center

    Marsh, Herbert W.; Ludtke, Oliver; Robitzsch, Alexander; Trautwein, Ulrich; Asparouhov, Tihomir; Muthen, Bengt; Nagengast, Benjamin

    2009-01-01

    This article is a methodological-substantive synergy. Methodologically, we demonstrate latent-variable contextual models that integrate structural equation models (with multiple indicators) and multilevel models. These models simultaneously control for and unconfound measurement error due to sampling of items at the individual (L1) and group (L2)…

  16. The importance of environmental variability and management control error to optimal harvest policies

    USGS Publications Warehouse

    Hunter, C.M.; Runge, M.C.

    2004-01-01

    State-dependent strategies (SDSs) are the most general form of harvest policy because they allow the harvest rate to depend, without constraint, on the state of the system. State-dependent strategies that provide an optimal harvest rate for any system state can be calculated, and stochasticity can be appropriately accommodated in this optimization. Stochasticity poses 2 challenges to harvest policies: (1) the population will never be at the equilibrium state; and (2) stochasticity induces uncertainty about future states. We investigated the effects of 2 types of stochasticity, environmental variability and management control error, on SDS harvest policies for a white-tailed deer (Odocoileus virginianus) model, and contrasted these with a harvest policy based on maximum sustainable yield (MSY). Increasing stochasticity resulted in more conservative SDSs; that is, higher population densities were required to support the same harvest rate, but these effects were generally small. As stochastic effects increased, SDSs performed much better than MSY. Both deterministic and stochastic SDSs maintained maximum mean annual harvest yield (AHY) and optimal equilibrium population size (Neq) in a stochastic environment, whereas an MSY policy could not. We suggest 3 rules of thumb for harvest management of long-lived vertebrates in stochastic systems: (1) an SDS is advantageous over an MSY policy, (2) using an SDS rather than an MSY is more important than whether a deterministic or stochastic SDS is used, and (3) for SDSs, rankings of the variability in management outcomes (e.g., harvest yield) resulting from parameter stochasticity can be predicted by rankings of the deterministic elasticities.

  17. Improved control strategy for PI-R current of DFIG considering voltage and current harmonics compensation

    NASA Astrophysics Data System (ADS)

    Song, S. Y.; Liu, Q. H.; Zhao, Y. N.; Liu, S. Y.

    2016-08-01

    With the rapid development of wind power generation, the related research of wind power control and integration issues has attracted much attention, and the focus of the research are shifting away from the ideal power grid environment to the actual power grid environment. As the main stream wind turbine generator, a doubly-fed induction generator (DFIG) is connected to the power grid directly by its stator, so it is particularly sensitive to the power grid. This paper studies the improvement of DFIG control technology in the power grid harmonic environment. Based on the DFIG dynamic model considering the power grid harmonic environment, this paper introduces the shortcomings of the common control strategy of DFIG, and puts forward the enhanced method. The decoupling control of the system is realized by compensating the coupling between the rotor harmonic voltage and harmonic current, improving the control performance. In addition, the simulation experiments on PSCAD/EMTDC are carried out to verify the correctness and effectiveness of the improved scheme.

  18. High-speed current dq PI controller for vector controlled PMSM drive.

    PubMed

    Marufuzzaman, Mohammad; Reaz, Mamun Bin Ibne; Rahman, Labonnah Farzana; Chang, Tae Gyu

    2014-01-01

    High-speed current controller for vector controlled permanent magnet synchronous motor (PMSM) is presented. The controller is developed based on modular design for faster calculation and uses fixed-point proportional-integral (PI) method for improved accuracy. Current dq controller is usually implemented in digital signal processor (DSP) based computer. However, DSP based solutions are reaching their physical limits, which are few microseconds. Besides, digital solutions suffer from high implementation cost. In this research, the overall controller is realizing in field programmable gate array (FPGA). FPGA implementation of the overall controlling algorithm will certainly trim down the execution time significantly to guarantee the steadiness of the motor. Agilent 16821A Logic Analyzer is employed to validate the result of the implemented design in FPGA. Experimental results indicate that the proposed current dq PI controller needs only 50 ns of execution time in 40 MHz clock, which is the lowest computational cycle for the era.

  19. High-Speed Current dq PI Controller for Vector Controlled PMSM Drive

    PubMed Central

    Reaz, Mamun Bin Ibne; Rahman, Labonnah Farzana; Chang, Tae Gyu

    2014-01-01

    High-speed current controller for vector controlled permanent magnet synchronous motor (PMSM) is presented. The controller is developed based on modular design for faster calculation and uses fixed-point proportional-integral (PI) method for improved accuracy. Current dq controller is usually implemented in digital signal processor (DSP) based computer. However, DSP based solutions are reaching their physical limits, which are few microseconds. Besides, digital solutions suffer from high implementation cost. In this research, the overall controller is realizing in field programmable gate array (FPGA). FPGA implementation of the overall controlling algorithm will certainly trim down the execution time significantly to guarantee the steadiness of the motor. Agilent 16821A Logic Analyzer is employed to validate the result of the implemented design in FPGA. Experimental results indicate that the proposed current dq PI controller needs only 50 ns of execution time in 40 MHz clock, which is the lowest computational cycle for the era. PMID:24574913

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

    PubMed

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

    2017-09-06

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

  1. A constrained-gradient method to control divergence errors in numerical MHD

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.

    2016-10-01

    In numerical magnetohydrodynamics (MHD), a major challenge is maintaining nabla \\cdot {B}=0. Constrained transport (CT) schemes achieve this but have been restricted to specific methods. For more general (meshless, moving-mesh, ALE) methods, `divergence-cleaning' schemes reduce the nabla \\cdot {B} errors; however they can still be significant and can lead to systematic errors which converge away slowly. We propose a new constrained gradient (CG) scheme which augments these with a projection step, and can be applied to any numerical scheme with a reconstruction. This iteratively approximates the least-squares minimizing, globally divergence-free reconstruction of the fluid. Unlike `locally divergence free' methods, this actually minimizes the numerically unstable nabla \\cdot {B} terms, without affecting the convergence order of the method. We implement this in the mesh-free code GIZMO and compare various test problems. Compared to cleaning schemes, our CG method reduces the maximum nabla \\cdot {B} errors by ˜1-3 orders of magnitude (˜2-5 dex below typical errors if no nabla \\cdot {B} cleaning is used). By preventing large nabla \\cdot {B} at discontinuities, this eliminates systematic errors at jumps. Our CG results are comparable to CT methods; for practical purposes, the nabla \\cdot {B} errors are eliminated. The cost is modest, ˜30 per cent of the hydro algorithm, and the CG correction can be implemented in a range of numerical MHD methods. While for many problems, we find Dedner-type cleaning schemes are sufficient for good results, we identify a range of problems where using only Powell or `8-wave' cleaning can produce order-of-magnitude errors.

  2. Current control in inertial Brownian motors by noise recycling

    NASA Astrophysics Data System (ADS)

    Jia, Zheng-Lin; Li, Kai-Yi; Li, Chun; Yang, Chun-Yan; Mei, Dong-Cheng

    2015-03-01

    The transport properties of an inertial Brownian motor were numerically studied in the presence of recycled noise, which is obtained by re-injecting a fraction of the primary white noise after a processing time, being introduced into the system in a multiplicative way. The simulation results indicate that various parameters such as the external driving force, the friction coefficient, the mass of the particle, the recycling strength, and the delay time can induce the current reversal phenomenon when the sign of the recycling strength is in agreement with the sign of the external bias force, otherwise the current reversal cannot be observed. Additionally, the asymptotic mean velocity as a function of the delay time of the recycled noise always shows a resonance-like behavior with the presence of a maximum current. These results demonstrate that the delay time and the recycling strength of the recycled noise can be used as the feasible and flexible control parameters for the amplitude and direction of the current.

  3. Design and control of the phase current of a brushless dc motor to eliminate cogging torque

    NASA Astrophysics Data System (ADS)

    Jang, G. H.; Lee, C. J.

    2006-04-01

    This paper presents a design and control method of the phase current to reduce the torque ripple of a brushless dc (BLDC) motor by eliminating cogging torque. The cogging torque is the main source of torque ripple and consequently of speed error, and it is also the excitation source to generate the vibration and noise of a motor. This research proposes a modified current wave form, which is composed of main and auxiliary currents. The former is the conventional current to generate the commutating torque. The latter generates the torque with the same magnitude and opposite sign of the corresponding cogging torque at the given position in order to eliminate the cogging torque. Time-stepping finite element method simulation considering pulse-width-modulation switching method has been performed to verify the effectiveness of the proposed method, and it shows that this proposed method reduces torque ripple by 36%. A digital-signal-processor-based controller is also developed to implement the proposed method, and it shows that this proposed method reduces the speed ripple significantly.

  4. Current status and strategies for viral hepatitis control in Korea.

    PubMed

    Sinn, Dong Hyun; Cho, Eun Ju; Kim, Ji Hoon; Kim, Do Young; Kim, Yoon Jun; Choi, Moon Seok

    2017-09-01

    Viral hepatitis is one of major global health challenges with increasing disease burden worldwide. Hepatitis B virus and hepatitis C virus infections are major causes of chronic liver diseases. They can lead to cirrhosis, hepatocellular carcinoma, and death in significant portion of affected people. Transmission of hepatitis B virus can be blocked by vaccination. Progression of hepatitis B virus-related liver diseases can be prevented by long-term viral suppression with effective drugs. Although vaccine for hepatitis C virus is currently unavailable, hepatitis C virus infection can be eradicated by oral direct antiviral agents. To eliminate viral hepatitis, World Health Organization (WHO) has urged countries to develop national goals and targets through reducing 90% of new infections and providing universal access to key treatment services up to 80%. This can lead to 65% reduction of viral hepatitis-related mortality. Here, we discuss some key features of viral hepatitis, strategies to control viral hepatitis suggested by WHO, and current status and strategies for viral hepatitis control in South Korea. To achieve the goal of viral hepatitis elimination by 2030 in South Korea, an independent 'viral hepatitis sector' in Centers for Disease Control & Prevention (CDC) needs to be established to organize and execute comprehensive strategy for the management of viral hepatitis in South Korea.

  5. High-side Digitally Current Controlled Biphasic Bipolar Microstimulator

    PubMed Central

    Hanson, Timothy L.; Ómarsson, Björn; O'Doherty, Joseph E.; Peikon, Ian D.; Lebedev, Mikhail; Nicolelis, Miguel AL.

    2012-01-01

    Electrical stimulation of nervous tissue has been extensively used as both a tool in experimental neuroscience research and as a method for restoring of neural functions in patients suffering from sensory and motor disabilities. In the central nervous system, intracortical microstimulation (ICMS) has been shown to be an effective method for inducing or biasing perception, including visual and tactile sensation. ICMS also holds promise for enabling brain-machine-brain interfaces (BMBIs) by directly writing information into the brain. Here we detail the design of a high-side, digitally current-controlled biphasic, bipolar microstimulator, and describe the validation of the device in vivo. As many applications of this technique, including BMBIs, require recording as well as stimulation, we pay careful attention to isolation of the stimulus channels and parasitic current injection. With the realized device and standard recording hardware - without active artifact rejection - we are able to observe stimulus artifacts of less than 2 ms in duration. PMID:22328184

  6. High-side digitally current controlled biphasic bipolar microstimulator.

    PubMed

    Hanson, Timothy L; Ómarsson, Björn; O'Doherty, Joseph E; Peikon, Ian D; Lebedev, Mikhail A; Nicolelis, Miguel A L

    2012-05-01

    Electrical stimulation of nervous tissue has been extensively used as both a tool in experimental neuroscience research and as a method for restoring of neural functions in patients suffering from sensory and motor disabilities. In the central nervous system, intracortical microstimulation (ICMS) has been shown to be an effective method for inducing or biasing perception, including visual and tactile sensation. ICMS also holds promise for enabling brain-machine-brain interfaces (BMBIs) by directly writing information into the brain. Here we detail the design of a high-side, digitally current-controlled biphasic, bipolar microstimulator, and describe the validation of the device in vivo. As many applications of this technique, including BMBIs, require recording as well as stimulation, we pay careful attention to isolation of the stimulus channels and parasitic current injection. With the realized device and standard recording hardware-without active artifact rejection-we are able to observe stimulus artifacts of less than 2 ms in duration.

  7. Design of a constant-voltage and constant-current controller with dual-loop and adaptive switching frequency control

    NASA Astrophysics Data System (ADS)

    Yingping, Chen; Zhiqian, Li

    2015-05-01

    A 5.0-V 2.0-A flyback power supply controller providing constant-voltage (CV) and constant-current (CC) output regulation without the use of an optical coupler is presented. Dual-close-loop control is proposed here due to its better regulation performance of tolerance over process and temperature compared with open loop control used in common. At the same time, the two modes, CC and CV, could switch to each other automatically and smoothly according to the output voltage level not sacrificing the regulation accuracy at the switching phase, which overcomes the drawback of the digital control scheme depending on a hysteresis comparator to change the mode. On-chip compensation using active capacitor multiplier technique is applied to stabilize the voltage loop, eliminate an additional package pin, and save on the die area. The system consumes as little as 100 mW at no-load condition without degrading the transient response performance by utilizing the adaptive switching frequency control mode. The proposed controller has been implemented in a commercial 0.35-μm 40-V BCD process, and the active chip area is 1.5 × 1.0 mm2. The total error of the output voltage due to line and load variations is less than ±1.7%.

  8. An analysis of a TDMA channel using stop-and-wait, block, and select-and-repeat ARQ error control

    NASA Astrophysics Data System (ADS)

    Saeki, B. H.; Rubin, I.

    1982-05-01

    In this paper, the multiaccess broadcast communication channel operating under a TDMA control discipline and employing an ARQ scheme is examined. The generating function of the message delay distribution is derived. The effects of nonzero bit error rates on multipacket messages under several stop-and-wait and block ARQ systems are incorporated. Numerical results for the steady-state mean and variance of the message delay are presented for a stationary transmission error process model in which errors occur as independent events. Results for this channel under a select-and-repeat ARQ system are developed for single packet messages. Stability requirements are stated, useful bounds on the average message delay at steady state are derived, and numerical examples are presented.

  9. Control of centrifugal blood pump based on the motor current.

    PubMed

    Iijima, T; Inamoto, T; Nogawa, M; Takatani, S

    1997-07-01

    In this study, centrifugal pump performance was examined in a mock circulatory loop to derive an automatic pump rotational speed (rpm) control method. The pivot bearing supported sealless centrifugal pump was placed in the left ventricular apex to aorta bypass mode. The pneumatic pulsatile ventricle was used to simulate the natural ventricle. To simulate the suction effect in the ventricle, a collapsible rubber tube was placed in the inflow port of the centrifugal pump in series with the apex of the simulated ventricle. Experimentally, the centrifugal pump speed (rpm) was gradually increased to simulate the suction effect. The pump flow through the centrifugal pump measured by an electromagnetic flowmeter, the aortic pressure, and the motor current were continuously digitized at 100 Hz and stored in a personal computer. The analysis of the cross-spectral density between the pump flow and motor current waveforms revealed that 2 waveforms were highly correlated at the frequency range between 0 and 4 Hz, with the coherence and phase angles being close to 1.0 and 0 degree, respectively. The fast Fourier transform analysis of the motor current indicated that the second harmonic component of the motor current power density increased with the occurrence of the suction effect in the circuit. The ratio of the fundamental to the second harmonic component decreased less than 1.3 as the suction effect developed in the circuit. It is possible to detect and prevent the suction effect of the centrifugal blood pump in the natural ventricle through analysis of the motor current waveform.

  10. Current Control and Future Risk in Asthma Management

    PubMed Central

    Sims, Erika J; Haughney, John; Ryan, Dermot; Thomas, Mike

    2011-01-01

    Despite international and national guidelines, poor asthma control remains an issue. Asthma exacerbations are costly to both the individual, and the healthcare provider. Improvements in our understanding of the therapeutic benefit of asthma therapies suggest that, in general, while long-acting bronchodilator therapy improves asthma symptoms, the anti-inflammatory activity of inhaled corticosteroids reduces acute asthma exacerbations. Studies have explored factors which could be predictive of exacerbations. A history of previous exacerbations, poor asthma control, poor inhaler technique, a history of lower respiratory tract infections, poor adherence to medication, the presence of allergic rhinitis, gastro-oesophageal reflux disease, psychological dysfunction, smoking and obesity have all been implicated as having a predictive role in the future risk of asthma exacerbation. Here we review the current literature and discuss this in the context of primary care management of asthma. PMID:21966601

  11. Controlled Levitation of Colloids through Direct Current Electric Fields.

    PubMed

    Silvera Batista, Carlos A; Rezvantalab, Hossein; Larson, Ronald G; Solomon, Michael J

    2017-07-07

    We report the controlled levitation of surface-modified colloids in direct current (dc) electric fields at distances as far as 75 μm from an electrode surface. Instead of experiencing electrophoretic deposition, colloids modified through metallic deposition or the covalent bonding of poly(ethylene glycol) (PEG) undergo migration and focusing that results in levitation at these large distances. The levitation is a sensitive function of the surface chemistry and magnitude of the field, thus providing the means to achieve control over the levitation height. Experiments with particles of different surface charge show that levitation occurs only when the absolute zeta potential is below a threshold value. An electrodiffusiophoretic mechanism is proposed to explain the observed large-scale levitation.

  12. Chaos control by electric current in an enzymatic reaction.

    PubMed

    Lekebusch, A; Förster, A; Schneider, F W

    1996-09-01

    We apply the continuous delayed feedback method of Pyragas to control chaos in the enzymatic Peroxidase-Oxidase (PO) reaction, using the electric current as the control parameter. At each data point in the time series, a time delayed feedback function applies a small amplitude perturbation to inert platinum electrodes, which causes redox processes on the surface of the electrodes. These perturbations are calculated as the difference between the previous (time delayed) signal and the actual signal. Unstable periodic P1, 1(1), and 1(2) orbits (UPOs) were stabilized in the CSTR (continuous stirred tank reactor) experiments. The stabilization is demonstrated by at least three conditions: A minimum in the experimental dispersion function, the equality of the delay time with the period of the stabilized attractor and the embedment of the stabilized periodic attractor in the chaotic attractor.

  13. Medicolegal implications of surgical errors and complications in neck surgery: A review based on the Italian current legislation

    PubMed Central

    Polistena, Andrea; Sanguinetti, Alessandro; Buccelli, Claudio; Conzo, Giovanni; Conti, Adelaide; Niola, Massimo; Avenia, Nicola

    2016-01-01

    Abstract Aim of the present paper is the review of the principal complications associated to endocrine neck surgery considering how expertise, full adoption of guidelines, appropriate technology and proper informed consent may limit the medicolegal claims at the light of the incoming new regulation of the medical professional legal responsibility. A literature search, using the Medline/PubMed database for full-length papers, was used. Postoperative recurrent laryngeal nerve (RLN) palsy and hypoparathy-roidism remain the principal causes of surgical malpractice claims . In the procedure of neck lymphadenctomy intra-operative haemorrhage, thoracic duct injury, injuries to loco-regional nerves can be observed and can be source of claims. After many years of increased medicolegal litigations, the Italian government is proposing a drastic change in the regulations of supposed medical malpractice in order to guarantee the patient’s right to a safe treatment and in the meantime to defend clinicians from often unmotivated and prejudicial legal cases. Surgical errors and complications in neck surgery are a relevant clinical issue. Only the combination of surgical and clinical expertise, application of guidelines, appropriate technology and a routinely use of specific informed consent can contain potential medicolegal implications. PMID:28352812

  14. Automatic parameter estimation of multicompartmental neuron models via minimization of trace error with control adjustment

    PubMed Central

    Goeritz, Marie L.; Marder, Eve

    2014-01-01

    We describe a new technique to fit conductance-based neuron models to intracellular voltage traces from isolated biological neurons. The biological neurons are recorded in current-clamp with pink (1/f) noise injected to perturb the activity of the neuron. The new algorithm finds a set of parameters that allows a multicompartmental model neuron to match the recorded voltage trace. Attempting to match a recorded voltage trace directly has a well-known problem: mismatch in the timing of action potentials between biological and model neuron is inevitable and results in poor phenomenological match between the model and data. Our approach avoids this by applying a weak control adjustment to the model to promote alignment during the fitting procedure. This approach is closely related to the control theoretic concept of a Luenberger observer. We tested this approach on synthetic data and on data recorded from an anterior gastric receptor neuron from the stomatogastric ganglion of the crab Cancer borealis. To test the flexibility of this approach, the synthetic data were constructed with conductance models that were different from the ones used in the fitting model. For both synthetic and biological data, the resultant models had good spike-timing accuracy. PMID:25008414

  15. Restoration and testing of an HTS fault current controller

    SciTech Connect

    Waynert, J. A.; Boenig, H.; Mielke, C. H.; Willis, J. O.; Burley, B. L.

    2002-01-01

    A three-phase, 1200 A, 12.5 kV fault current controller using three HTS 4 mH coils, was built by industry and tested in 1999 at the Center Substation of Southern California Edison in Norwalk, CA. During the testing, it appeared that each of the three single-phase units had experienced a voltage breakdown, one externally and two internally. Los Alamos National Laboratory (LANL) was asked by DOE to restore the operation of the fault current controller provided the HTS coils had not been damaged during the initial substation tests. When the internally-failed coil vacuum vessels were opened it became evident that in these two vessels, a flashover had occurred at the high voltage bus section leading to the terminals of the superconducting coil. An investigation into the failure mechanism resulted in six possible causes for the flashover. Based on these causes, the high voltage bus was completely redesigned. Single-phase tests were successfully performed on the modified unit at a 13.7 kV LANL substation. This paper presents the postulated voltage flashover failure mechanisms, the new high voltage bus design which mitigates the failure mechanisms, the sequence of tests used to validate the new design, and finally, the results of variable load and short-circuit tests with the single-phase unit operating on the LANL 13.7 kV substation.

  16. Error estimates for approximate dynamic systems. [linear and nonlinear control systems of different dimensions

    NASA Technical Reports Server (NTRS)

    Gunderson, R. W.; George, J. H.

    1974-01-01

    Two approaches are investigated for obtaining estimates on the error between approximate and exact solutions of dynamic systems. The first method is primarily useful if the system is nonlinear and of low dimension. The second requires construction of a system of v-functions but is useful for higher dimensional systems, either linear or nonlinear.

  17. IMPROVEMENT OF SMVGEAR II ON VECTOR AND SCALAR MACHINES THROUGH ABSOLUTE ERROR TOLERANCE CONTROL (R823186)

    EPA Science Inventory

    The computer speed of SMVGEAR II was improved markedly on scalar and vector machines with relatively little loss in accuracy. The improvement was due to a method of frequently recalculating the absolute error tolerance instead of keeping it constant for a given set of chemistry. ...

  18. Reducing Check-in Errors at Brigham Young University through Statistical Process Control

    ERIC Educational Resources Information Center

    Spackman, N. Andrew

    2005-01-01

    The relationship between the library and its patrons is damaged and the library's reputation suffers when returned items are not checked in. An informal survey reveals librarians' concern for this problem and their efforts to combat it, although few libraries collect objective measurements of errors or the effects of improvement efforts. Brigham…

  19. Error-based adaptive non-linear control and regions of feasibility

    NASA Technical Reports Server (NTRS)

    Teel, Andrew R.

    1992-01-01

    The nonlinear adaptive algorithm of Kanellakopoulos et al. (1991) was modified to produce an error-based algorithm. This permits global stabilizability for a large subset of pure-feedback nonlinear systems. The algorithm was demonstrated on the single-input stabilization problem, but extends easily to the multiple input tracking problems.

  20. Error estimates for approximate dynamic systems. [linear and nonlinear control systems of different dimensions

    NASA Technical Reports Server (NTRS)

    Gunderson, R. W.; George, J. H.

    1974-01-01

    Two approaches are investigated for obtaining estimates on the error between approximate and exact solutions of dynamic systems. The first method is primarily useful if the system is nonlinear and of low dimension. The second requires construction of a system of v-functions but is useful for higher dimensional systems, either linear or nonlinear.

  1. IMPROVEMENT OF SMVGEAR II ON VECTOR AND SCALAR MACHINES THROUGH ABSOLUTE ERROR TOLERANCE CONTROL (R823186)

    EPA Science Inventory

    The computer speed of SMVGEAR II was improved markedly on scalar and vector machines with relatively little loss in accuracy. The improvement was due to a method of frequently recalculating the absolute error tolerance instead of keeping it constant for a given set of chemistry. ...

  2. Global Positioning System Control/User Segments. Volume II. System Error Performance.

    DTIC Science & Technology

    RADIO NAVIGATION, *NAVIGATION SATELLITES, * POSITION FINDING, *NAVIGATION COMPUTERS, *IONOSPHERIC PROPAGATION, GLOBAL , EPHEMERIDES, TRADE OFF...ANALYSIS, SPACEBORNE, ERRORS, VELOCITY, SYSTEMS ENGINEERING, DIGITAL COMPUTERS, MEMORY DEVICES, TIME SIGNALS, SITE SELECTION, GROUND STATIONS, MOTION, MATHEMATICAL MODELS, ALGORITHMS, PERFORMANCE(ENGINEERING), USER NEEDS, S BAND, L BAND.

  3. Strategy to control type I error increases power to identify genetic variation using the full biological trajectory.

    PubMed

    Benke, K S; Wu, Y; Fallin, D M; Maher, B; Palmer, L J

    2013-07-01

    Genome-wide association studies have been successful in identifying loci that underlie continuous traits measured at a single time point. To additionally consider continuous traits longitudinally, it is desirable to look at SNP effects at baseline and over time using linear-mixed effects models. Estimation and interpretation of two coefficients in the same model raises concern regarding the optimal control of type I error. To investigate this issue, we calculate type I error and power under an alternative for joint tests, including the two degree of freedom likelihood ratio test, and compare this to single degree of freedom tests for each effect separately at varying alpha levels. We show which joint tests are the optimal way to control the type I error and also illustrate that information can be gained by joint testing in situations where either or both SNP effects are underpowered. We also show that closed form power calculations can approximate simulated power for the case of balanced data, provide reasonable approximations for imbalanced data, but overestimate power for complicated residual error structures. We conclude that a two degree of freedom test is an attractive strategy in a hypothesis-free genome-wide setting and recommend its use for genome-wide studies employing linear-mixed effects models.

  4. Strategy to Control Type I Error Increases Power to Identify Genetic Variation Using the Full Biological Trajectory

    PubMed Central

    Benke, K. S.; Wu, Y.; Fallin, D. M.; Maher, B.; Palmer, L. J.

    2013-01-01

    Genome-wide association studies have been successful in identifying loci that underlie continuous traits measured at a single time point. To additionally consider continuous traits longitudinally, it is desirable to look at SNP effects at baseline and over time using linear-mixed effects models. Estimation and interpretation of two coefficients in the same model raises concern regarding the optimal control of type I error. To investigate this issue, we calculate type I error and power under an alternative for joint tests, including the two degree of freedom likelihood ratio test, and compare this to single degree of freedom tests for each effect separately at varying alpha levels. We show which joint tests are the optimal way to control the type I error and also illustrate that information can be gained by joint testing in situations where either or both SNP effects are underpowered. We also show that closed form power calculations can approximate simulated power for the case of balanced data, provide reasonable approximations for imbalanced data, but overestimate power for complicated residual error structures. We conclude that a two degree of freedom test is an attractive strategy in a hypothesis-free genome-wide setting and recommend its use for genome-wide studies employing linear-mixed effects models. PMID:23633177

  5. Current-controlled unidirectional edge-meron motion

    NASA Astrophysics Data System (ADS)

    Xing, Xiangjun; Pong, Philip W. T.; Zhou, Yan

    2016-11-01

    In order to address many of the challenges and bottlenecks currently experienced by traditional charge-based technologies, various alternatives are being actively explored to provide potential solutions of device miniaturization and scaling in the post-Moore's-law era. Amongst these alternatives, spintronic physics and devices have recently attracted rapidly increasing interest by exploiting the additional degree of electrons-spin. For example, magnetic domain-wall racetrack-memory and logic devices have been realized via manipulating domain-wall motion. As compared to domain-wall-based devices, magnetic skyrmions have the advantages of ultrasmall size (typically 5-100 nm in diameter), facile current-driven motion, topological stability, and peculiar emergent electrodynamics, promising for next-generation electronics applications in the post-Moore's-law regime. Here, a magnetic meron device, which behaves similarly to a PN-junction diode, is demonstrated for the first time, by tailoring the current-controlled unidirectional motion of edge-merons (i.e., fractional skyrmions) in a nanotrack with interfacial Dzyaloshinskii-Moriya interaction. The working principles of the meron device, theoretically predicted from the Thiele equation for topological magnetic objects, are further verified using micromagnetic simulations. The present study has revealed the topology-independent transport property of different magnetic objects and is expected to open the vista toward integrated composite circuitry (with unified data storage and processing) based on a single magnetic chip, as the meron device can be used, either as a building block to develop complex logic components or as a signal controller to interconnect skyrmion, domain-wall, and even spin-wave devices.

  6. [Errors in bibliographic references of Nefrología from 1981 to 1995. A quality control].

    PubMed

    Pérez García, A

    2000-01-01

    The accuracy of the reference list is considered an essential factor in determining the quality of a scientific publication, and has been reviewed and published in several medical journals. The rate of citation errors in NEFROLOGIA has not been published before. The aim of this study has been to examine the accuracy of the references citation in the numbers of the journal published for a period of 15 years, from the first issue in 1981 to the last one on 1995. In this period 68 ordinary issues of the journal were published, with 520 original articles that constituted the data base, 87 articles were selected applying a table of random numbers with 5 references of each article selected to be reviewed with a total of 435. The accuracy of the name of the authors, title of the article, volume, initial and last page and year of publication were evaluated, accordingly with the NEFROLOGIA normative. Citation errors were considered major or minor depending on whether they prevented or not the immediate retrieval of the article listed. Of the 435 citations examined, 433 could be located, being impossible in 2 with the data supplied. In 189 (43.45%) 237 errors were detected, with 13.50% of them being considered major and 86.50% minor, with the greatest percentage of errors occurring in the data about the authors of the articles referenced 96 (40.50%). The issues of NEFROLOGIA published in this period present a high number of bibliographic reference errors, being the rate similar to other evaluated scientific periodical journals. This fact should be improved, and authors and reviewers should thoroughly check their references in order to avoid these mistakes, as they affect the quality standard of the publication.

  7. Water-level controls on macro-tidal rip currents

    NASA Astrophysics Data System (ADS)

    Austin, Martin J.; Masselink, Gerd; Scott, Tim M.; Russell, Paul E.

    2014-03-01

    Field measurements and numerical modelling have been used to investigate the water-level control of rip current dynamics on a macro-tidal beach. Field data collected over 32 complete tidal cycles, spanning a range of wave and tide conditions, demonstrate that rip current strength and behaviour is modulated at the semi-diurnal frequency by tide-induced changes in the water-level over bar/rip morphology. Peak flow speeds in the rip neck correspond to the time of maximum wave breaking 1.5 h before and after low water. Alongshore-directed water surface gradients ∂η/∂y were measured along the feeder channel and around the ends of the inter-tidal bar, with head differences O(0.1 m). The numerical model reproduced ∂η/∂y with a good level of skill and showed that ∂η/∂y and increase with the proportion of breaking waves Qb over the inter-tidal bar; but was maximised during peak Qb, maximum ∂η/∂y occurred when wave breaking moved offshore to the sub-tidal bar and Qb was reduced. Around low water, the forcing of the rip current by the alongshore pressure-driven feeder current was reduced by the decrease in Qb over the bar and feeder regions, but an offshore flow through the rip channel was maintained by a localised intensification of ∂η/∂y around the ends of the inter-tidal bar.

  8. DSP-based adaptive backstepping using the tracking errors for high-performance sensorless speed control of induction motor drive.

    PubMed

    Zaafouri, Abderrahmen; Ben Regaya, Chiheb; Ben Azza, Hechmi; Châari, Abdelkader

    2016-01-01

    This paper presents a modified structure of the backstepping nonlinear control of the induction motor (IM) fitted with an adaptive backstepping speed observer. The control design is based on the backstepping technique complemented by the introduction of integral tracking errors action to improve its robustness. Unlike other research performed on backstepping control with integral action, the control law developed in this paper does not propose the increase of the number of system state so as not increase the complexity of differential equations resolution. The digital simulation and experimental results show the effectiveness of the proposed control compared to the conventional PI control. The results analysis shows the characteristic robustness of the adaptive control to disturbances of the load, the speed variation and low speed.

  9. Feedback Error Learning Controller for Functional Electrical Stimulation Assistance in a Hybrid Robotic System for Reaching Rehabilitation.

    PubMed

    Resquín, Francisco; Gonzalez-Vargas, Jose; Ibáñez, Jaime; Brunetti, Fernando; Pons, José Luis

    2016-06-13

    Hybrid robotic systems represent a novel research field, where functional electrical stimulation (FES) is combined with a robotic device for rehabilitation of motor impairment. Under this approach, the design of robust FES controllers still remains an open challenge. In this work, we aimed at developing a learning FES controller to assist in the performance of reaching movements in a simple hybrid robotic system setting. We implemented a Feedback Error Learning (FEL) control strategy consisting of a feedback PID controller and a feedforward controller based on a neural network. A passive exoskeleton complemented the FES controller by compensating the effects of gravity. We carried out experiments with healthy subjects to validate the performance of the system. Results show that the FEL control strategy is able to adjust the FES intensity to track the desired trajectory accurately without the need of a previous mathematical model.

  10. Feedback Error Learning Controller for Functional Electrical Stimulation Assistance in a Hybrid Robotic System for Reaching Rehabilitation

    PubMed Central

    Resquín, Francisco; Gonzalez-Vargas, Jose; Ibáñez, Jaime; Brunetti, Fernando; Pons, José Luis

    2016-01-01

    Hybrid robotic systems represent a novel research field, where functional electrical stimulation (FES) is combined with a robotic device for rehabilitation of motor impairment. Under this approach, the design of robust FES controllers still remains an open challenge. In this work, we aimed at developing a learning FES controller to assist in the performance of reaching movements in a simple hybrid robotic system setting. We implemented a Feedback Error Learning (FEL) control strategy consisting of a feedback PID controller and a feedforward controller based on a neural network. A passive exoskeleton complemented the FES controller by compensating the effects of gravity. We carried out experiments with healthy subjects to validate the performance of the system. Results show that the FEL control strategy is able to adjust the FES intensity to track the desired trajectory accurately without the need of a previous mathematical model. PMID:27990245

  11. Tiso Adjustable Filter with Controllable Controlled-Gain Voltage Differencing Current Conveyor

    NASA Astrophysics Data System (ADS)

    Jerabek, Jan; Sotner, Roman; Vrba, Kamil

    2014-05-01

    The main aim of this paper is to present solution of triple-input single-output (TISO) filter with independently adjustable pole frequency, quality factor, bandwidth and also gain. Filter is universal, operates in current mode and includes only one active element - the so-called Controlled-Gain Voltage Differencing Current Conveyor (CG-VDCC) with two controllable parameters: transconductance (gm) and gain of output currents (BX ). Implementation of CG-VDCC element in 0.18 μm CMOS technology is also included and this model is used in proposed filter simulations.

  12. [Current concepts of polytrauma management: from ATLS to "damage control"].

    PubMed

    Stahel, P F; Heyde, C E; Wyrwich, W; Ertel, W

    2005-09-01

    In recent years, the implementation of standardized protocols for polytrauma management has led to a significant improvement in trauma care as well as to a decrease in post-traumatic morbidity and mortality. As such, the "Advanced Trauma Life Support" (ATLS) protocol of the American College of Surgeons for the acute management of severely injured patients has been established as a gold standard in most European countries since the 1990s. Continuative concepts to the ATLS program include the "Definitive Surgical Trauma Care" (DSTC) algorithm and the concept of "damage control" surgery for polytraumatized patients with immediate life-threatening injuries. These phase-oriented therapeutic strategies appraise the injured patient of the whole extent of the sustained injuries and are in sharp contrast to previous modalities of "early total care" which advocate immediate definitive surgical intervention. The approach of "damage control" surgery takes into account the influence of systemic post-traumatic inflammatory and metabolic reactions of the organism and is aimed at reducing both the primary and the secondary, delayed, mortality in severely injured patients. The present paper provides an overview of the current state of management algorithms for polytrauma patients, with a focus on the standard concepts of ATLS and "damage control".

  13. Delayed and current stimulus control in successive discriminations

    PubMed Central

    White, K. Geoffrey

    1990-01-01

    In a successive discrimination in which successively alternating red and green hues signaled component variable-interval schedules, sensitivity of the ratio of responses in the two components to variation in the component reinforcer ratio decreased systematically during the course of the component. This decrease in stimulus control or discrimination over the course of the component was shown to be the result of delayed control of responding during the component by the stimulus transition between components. When the red–green stimulus transition was altered by interpolating a white stimulus at the end of each 60-s component, discrimination at the beginning of the component (measured by the power-function exponent for sensitivity to reinforcement) was reduced. Conditions with the white stimulus inserted in other quarters of the component indicated that the current discriminative stimulus exerts control over responding throughout the component, whereas during about the first half of the component, response differentials are influenced by the transition between discriminative stimuli. PMID:16812614

  14. A survey-based study of wrong-level lumbar spine surgery: the scope of the problem and current practices in place to help avoid these errors.

    PubMed

    Groff, Michael W; Heller, Joshua E; Potts, Eric A; Mummaneni, Praveen V; Shaffrey, Christopher I; Smith, Justin S

    2013-01-01

    To understand better the scope of wrong-level lumbar spine surgery and current practices in place to help avoid such errors. The Joint Section on Disorders of the Spine and Peripheral Nerves (Spine Section) developed a survey on single-level lumbar spine decompression surgery. Invitations to complete the Web-based survey were sent to all Spine Section members. Respondents were assured of confidentiality. There were 569 responses from 1045 requests (54%). Most surgeons either routinely (74%) or sometimes (11%) obtain preoperative imaging for incision planning. Most surgeons indicated that they obtained imaging after the incision was performed for localization either routinely before bone removal (73%) or most frequently before bone removal but occasionally after (16%). Almost 50% of reporting surgeons have performed wrong-level lumbar spine surgery at least once, and >10% have performed wrong-side lumbar spine surgery at least once. Nearly 20% of responding surgeons have been the subject of at least one malpractice case relating to these errors. Only 40% of respondents believed that the site marking/"time out" protocol of The Joint Commission on the Accreditation of Healthcare Organizations has led to a reduction in these errors. There is substantial heterogeneity in approaches used to localize operative levels in the lumbar spine. Existing safety protocols may not be mitigating wrong-level surgery to the extent previously thought. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Advanced Techniques for Neoclassical Tearing Mode Control by Electron Cyclotron Current Drive in DIII-D

    NASA Astrophysics Data System (ADS)

    Volpe, F.

    2008-11-01

    Novel techniques have been developed in DIII-D for (1) control of rapidly rotating neoclassical tearing modes (NTMs) and (2) control of NTMs that have locked to a residual error field or the resistive wall. Electron cyclotron current drive (ECCD) has been successful at suppression of NTMs in present tokamaks, but will face new challenges in ITER where NTMs are expected to be more prone to locking. In order to avoid locking, rotating islands must be controlled at small widths that are expected to be narrower than the ECCD deposition. Under these conditions, modulated ECCD is predicted to stabilize more efficiently than continuous current drive. (1) A new technique developed at DIII-D detects the island using oblique electron cyclotron emission with a line of sight equivalent to that of the ECCD. This removes much of the uncertainty in mapping the island structure from the detector to the current drive location. This method was used both to measure the radial alignment between ECCD and the island, and to synchronize the modulation in phase with the island O-point, successfully stabilizing an NTM with mode numbers m/n=3/2. (2) If islands do grow large enough to lock, locked mode control will be necessary for recovery or avoiding disruption in ITER. A potential difficulty associated with locking is that the mode can lock in a position not necessarily accessible to ECCD. To obviate this problem, magnetic perturbations were used for the first time to unlock and reposition a locked m/n=2/1 mode in order to bring it in view of the gyrotron beam, leading to a significant reduction in island size. Once unlocked, magnetic perturbations were also used to sustain and control the mode rotation, which has the potential for easier ECCD modulation

  16. The effect of a clinical pharmacist-led training programme on intravenous medication errors: a controlled before and after study.

    PubMed

    Nguyen, Huong-Thao; Pham, Hong-Tham; Vo, Dang-Khoa; Nguyen, Tuan-Dung; van den Heuvel, Edwin R; Haaijer-Ruskamp, Flora M; Taxis, Katja

    2014-04-01

    Little is known about interventions to reduce intravenous medication administration errors in hospitals, especially in low- and middle-income countries. To assess the effect of a clinical pharmacist-led training programme on clinically relevant errors during intravenous medication preparation and administration in a Vietnamese hospital. A controlled before and after study with baseline and follow-up measurements was conducted in an intensive care unit (ICU) and a post-surgical unit (PSU). The intervention comprised lectures, practical ward-based teaching sessions and protocols/guidelines, and was conducted by a clinical pharmacist and a nurse. Data on intravenous medication preparation and administration errors were collected by direct observation 12 h/day for seven consecutive days. Generalised estimating equations (GEE) were used to assess the effect of the intervention on the prevalence of clinically relevant erroneous doses, corrected for confounding factors. 1204 intravenous doses were included, 516 during the baseline period (236 on ICU and 280 on PSU) and 688 during the follow-up period (407 on ICU and 281 on PSU). The prevalence of clinically relevant erroneous doses decreased significantly on the intervention ward (ICU) from 64.0% to 48.9% (p<0.001) but was unchanged on the control ward (PSU) (57.9% vs 64.1%; p=0.132). GEE analysis showed that doses on the intervention ward were 2.60 (1.27-5.31) times less likely to have clinically relevant errors (p=0.013). The pharmacist-led training programme was effective, but the error rate remained relatively high. Further quality improvement strategies are needed, including changes to the working environment and promotion of a safety culture.

  17. Application of generalized minimum distance decoding to hybrid-ARQ error control

    NASA Astrophysics Data System (ADS)

    Rice, Michael

    1994-02-01

    Generalized Minimum Distance (GMD) decoding is modified to allow simultaneous error detection and error correction. The soft-decision information retained by the generalized minimum distance concept is used as a source of reliability information which determines when a retransmission of the received packet should be requested. The performance of hybrid-ARQ GMD decoding is shown to be comparable to the ideal reliability metrics proposed by Loeliger and superior to the performance of hard-decision decoders. Performance expressions are derived for low to moderate signal-to-noise ratios and bounds are derived for high signal-to-noise ratios which are loose by 0.5 to 1.0 dB.

  18. The ``glass`` control room and human error in the nuclear power plant

    SciTech Connect

    Bennett, C.T.; Kimura, C.Y.

    1992-10-15

    We discuss the design philosophy that should be applied to a nuclear facility using electronic, ``glass`` displays for presentation critical information. A brief history of and problems related to the use of electronic displays in the aviation industry is presented, along with the parallel history of the use of electronic displays in the nuclear power industry. These discussions are followed by a discussion of the display guidelines that should be considered to minimize human error, and maximize safety and performance.

  19. The glass'' control room and human error in the nuclear power plant

    SciTech Connect

    Bennett, C.T.; Kimura, C.Y.

    1992-10-15

    We discuss the design philosophy that should be applied to a nuclear facility using electronic, glass'' displays for presentation critical information. A brief history of and problems related to the use of electronic displays in the aviation industry is presented, along with the parallel history of the use of electronic displays in the nuclear power industry. These discussions are followed by a discussion of the display guidelines that should be considered to minimize human error, and maximize safety and performance.

  20. Survey of current and emerging technologies for biological contamination control

    NASA Astrophysics Data System (ADS)

    Frick, Andreas; Mogul, Rakesh

    2012-07-01

    This study will survey current and emerging technologies for biological contamination control within the context of planetary protection. Using a systems analysis approach, our objective is to compare various implementation variables across tasks ranging from surface cleaning to full-system sterilization for spacecraft and spacecraft components. Methods reviewed include vapor-phase hydrogen peroxide, plasma-phase sterilants such as oxygen and hydrogen peroxide, dry heat, laser-based techniques, supercritical carbon dioxide-based methods, and advanced bio-barriers. These methods will be evaluated in relation to relevant mission architectures and will address aspects of sample return missions. Results from this study, therefore, will offer new insights into the present-day engineering capabilities and future developmental concerns for missions targeting icy satellites, Mars, and other locations of astrochemical and astrobiological significance.

  1. Control Spin Current and Data Recording on Spin Storage Medium

    NASA Astrophysics Data System (ADS)

    Krupa, M. M.

    2014-12-01

    The paper presents the results of experimental studies of the physical mechanisms and dynamics of magnetization reversal of the films Al2O3/Tb25Co5Fe70/Al2O3, Al2O3/Tb22Co5Fe73/Al2O3, Al2O3/Tb19Co5Fe76/Al2O3, Al2O3/Co30Fe70/Al2O3 with a single magnetic layer and the films Al2O3/Tb22Co5Fe73/Pr6O11/Tb19Co5Fe76/Al2O3, Al2O3/Co80Fe20/Pr6O11/Co30Fe70/Al2O3 with two magnetic layers radiated by picosecond (τi ≈ 80 ps) and femtosecond (τi ≈ 130 fs) laser pulses. The experimental samples of spin transistors and data recording devices on the spin storage medium are also described. The results of studies have shown that magnetic switching effects in the nanolayers under femtosecond laser pulses can be used for creation of systems of high-speed controlling of spin currents with the response time τ ≤ 10-11s. Conclusions from the studies are the following: thermomagnetic switching under the influence of an external magnetic field or a demagnetization field, magnetic switching of antiferromagnetic films under the influence of an effective internal field of antiferromagnetic interaction between magnetic sublattices rare-earth and transitive metals, magnetic switching under the influence of a magnetic field of the inverse Faraday effect, or under the influence of a magnetic field of a spin current. The magnetic switching of magnetic layers under action of the magnetic field of a spin current is the most important for practical use in elements of spintronics. This mechanism of magnetic reversal takes place only in multilayer nanofilms and the heterogeneous multilayer magnetic nanofilms are the base material for creation of spintronic devices. The great advantage of the magnetization reversal of magnetic nanolayers of the spin current is that the mechanism of magnetization reversal is working in the films with perpendicular anisotropy and in the films with in-plane anisotropy. The injection of polarized electrons can also be realized using short electrical pulses. That is

  2. Hybrid ARQ Error-Controlling Scheme for Robust and Efficient Transmission of UWB Body Area Networks

    NASA Astrophysics Data System (ADS)

    Suzuki, Haruka; Hernandez, Marco; Kohno, Ryuji

    This paper presents hybrid type-II automatic repeat request (H-ARQ) for wireless wearable body area networks (BANs) based on ultra wideband (UWB) technology. The proposed model is based on three schemes, namely, high rate optimized rate compatible punctured convolutional codes (HRO-RCPC), Reed Solomon (RS) invertible codes and their concatenation. Forward error correction (FEC) coding is combined with simple cyclic redundancy check (CRC) error detection. The performance is investigated for two channels: CM3 (on-body to on-body) and CM4 (on-body to a gateway) scenarios of the IEEE802.15.6 BAN channel models for BANs. It is shown that the improvement in performance in terms of throughput and error protection robustness is very significant. Thus, the proposed H-ARQ schemes can be employed and optimized to suit medical and non-medical applications. In particular we propose the use of FEC coding for non-medical applications as those require less stringent quality of service (QoS), while the incremental redundancy and ARQ configuration is utilized only for medical applications. Thus, higher QoS is guaranteed for medical application of BANs while allowing coexistence with non-medical applications.

  3. Improved current control makes inverters the power sources of choice

    SciTech Connect

    Yamamoto, H.; Harada, S.; Ueyama, T.

    1997-02-01

    It is now generally understood that by increasing the operating or switching frequency of a power source the size of the main transformer and main reactor can be shrunk. Thus, a 300-A DC welding power source weighing well under 100 lb can be produced. This makes the inverter power source an ideal choice for applications requiring equipment maneuverability. It is also generally understood that due to higher switching frequencies, a smoother output is obtained from inverter power sources. In the late 1980s, the company developed a new double-inverter power source by which inverted DC weld output is inverted back to AC weld output. This product was the first of its kind in the world. Again, the small compact size of this product was of great interest. Utilizing current waveform control, it was realized that fast response switching from electrode negative to electrode positive could be accurately controlled, offering benefits such as AC GTA welding with high-frequency start only, even at a low welding current. The primary benefit is the ability to limit the electrode positive half cycle to less than 5%. The electrode positive half cycle is responsible for tungsten erosion, which also creates the balling effect of a tungsten electrode. By limiting the electrode positive portion of the AC cycle to a very low level, a rather sharp point can be maintained on the tungsten, which creates a very concentrated, focused arc column. This ability provides excellent joint penetration in fillet welding of aluminum alloys, especially on thick plate. It also reduces the heat-affected zone in AC GTA welding of aluminum.

  4. Serbia National Poison Control Centre: organization and current activities.

    PubMed

    Jovanović, Dugan; Joksović, Dragan; Vucinić, Savica; Todorović, Veljko; Segrt, Zoran; Kilibarda, Vesna; Bokonjić, Dubravko

    2005-01-01

    Ministry of Health of the former Federal Republic of Yugoslavia established the National Poison Control Centre in 1995. However, that was only the formally solution since clinical, analytical and experimental services in toxicology had worked independently for at least 40 years. Besides the Headquarters, NPCC has currently 2 main units, the Clinic of Emergency and Clinical Toxicology and Pharmacology and the Institute of Toxicology and Pharmacology. The latter is consisted of Toxicological Information Department, Department of Analytical Toxicology and Department of Experimental Toxicology and Pharmacology. The Mobile Toxicological Chemical Unit is a separate department that is activated from personnel of the NPCC in a case of chemical accidents and/or disasters. Clinical, information and analytical parts of NPCC have a 365-day/24-hour working service. The Clinic of Emergency and Clinical Toxicology and Pharmacology is a place where the intoxicated patients are treated, including those that need the intensive care measures. Toxicological Information Department uses the data from a self-made computer Database for different information purposes. Department of Analytical Toxicology is equipped with a lot of contemporary analytical equipment that is giving the opportunity of identification and quantification of chemicals/metabolites/degradation products in biological material, food, water, air and soil. Basic pharmacological and toxicological research of chemicals and pre-clinical investigations of antidotes are realized in the Department of Experimental Toxicology and Pharmacology. In terms of medical prevention and rational treatment of human poison exposures in Serbia, the current organization of NPCC has so far proven to be effective.

  5. Two-stage group sequential robust tests in family-based association studies: controlling type I error.

    PubMed

    Yan, Lihan K; Zheng, Gang; Li, Zhaohai

    2008-07-01

    In family-based association studies, an optimal test statistic with asymptotic normal distribution is available when the underlying genetic model is known (e.g., recessive, additive, multiplicative, or dominant). In practice, however, genetic models for many complex diseases are usually unknown. Using a single test statistic optimal for one genetic model may lose substantial power when the model is mis-specified. When a family of genetic models is scientifically plausible, the maximum of several tests, each optimal for a specific genetic model, is robust against the model mis-specification. This robust test is preferred over a single optimal test. Recently, cost-effective group sequential approaches have been introduced to genetic studies. The group sequential approach allows interim analyses and has been applied to many test statistics, but not to the maximum statistic. When the group sequential method is applied, type I error should be controlled. We propose and compare several approaches of controlling type I error rates when group sequential analysis is conducted with the maximum test for family-based candidate-gene association studies. For a two-stage group sequential robust procedure with a single interim analysis, two critical values for the maximum tests are provided based on a given alpha spending function to control the desired overall type I error.

  6. A Bayesian approach to strengthen inference for case-control studies with multiple error-prone exposure assessments.

    PubMed

    Zhang, Jing; Cole, Stephen R; Richardson, David B; Chu, Haitao

    2013-11-10

    In case-control studies, exposure assessments are almost always error-prone. In the absence of a gold standard, two or more assessment approaches are often used to classify people with respect to exposure. Each imperfect assessment tool may lead to misclassification of exposure assignment; the exposure misclassification may be differential with respect to case status or not; and, the errors in exposure classification under the different approaches may be independent (conditional upon the true exposure status) or not. Although methods have been proposed to study diagnostic accuracy in the absence of a gold standard, these methods are infrequently used in case-control studies to correct exposure misclassification that is simultaneously differential and dependent. In this paper, we proposed a Bayesian method to estimate the measurement-error corrected exposure-disease association, accounting for both differential and dependent misclassification. The performance of the proposed method is investigated using simulations, which show that the proposed approach works well, as well as an application to a case-control study assessing the association between asbestos exposure and mesothelioma.

  7. Reducing prospective memory error and costs in simulated air traffic control: External aids, extending practice, and removing perceived memory requirements.

    PubMed

    Loft, Shayne; Chapman, Melissa; Smith, Rebekah E

    2016-09-01

    In air traffic control (ATC), forgetting to perform deferred actions-prospective memory (PM) errors-can have severe consequences. PM demands can also interfere with ongoing tasks (costs). We examined the extent to which PM errors and costs were reduced in simulated ATC by providing extended practice, or by providing external aids combined with extended practice, or by providing external aids combined with instructions that removed perceived memory requirements. Participants accepted/handed-off aircraft and detected conflicts. For the PM task, participants were required to substitute alternative actions for routine actions when accepting aircraft. In Experiment 1, when no aids were provided, PM errors and costs were not reduced by practice. When aids were provided, costs observed early in practice were eliminated with practice, but residual PM errors remained. Experiment 2 provided more limited practice with aids, but instructions that did not frame the PM task as a "memory" task led to high PM accuracy without costs. Attention-allocation policies that participants set based on expected PM demands were modified as individuals were increasingly exposed to reliable aids, or were given instructions that removed perceived memory requirements. These findings have implications for the design of aids for individuals who monitor multi-item dynamic displays. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  8. Seizing Control: From Current Treatments to Optogenetic Interventions in Epilepsy

    PubMed Central

    Bui, Anh D.; Alexander, Allyson; Soltesz, Ivan

    2016-01-01

    The unpredictability and severity of seizures contribute to the debilitating nature of epilepsy. These factors also render the condition particularly challenging to treat, as an ideal treatment would need to detect and halt the pathological bursts of hyperactivity without disrupting normal brain activity. Optogenetic techniques offer promising tools to study and perhaps eventually treat this episodic disorder by controlling specific brain circuits in epileptic animals with great temporal precision. Here, we briefly review the current treatment options for patients with epilepsy. We then describe the many ways optogenetics has allowed us to untangle the microcircuits involved in seizure activity, and how it has, in some cases, changed our perception of previous theories of seizure generation. Control of seizures with light is no longer a dream, and has been achieved in numerous different animal models of epilepsy. Beyond its application as a seizure suppressor, we highlight another facet of optogenetics in epilepsy, namely the ability to create “on-demand” seizures, as a tool to systematically probe the dynamics of networks during seizure initiation and propagation. Finally, we look into the future to discuss the possibilities and challenges of translating optogenetic techniques to clinical use. PMID:26700888

  9. Current Status of Malaria and Potential for Control

    PubMed Central

    Phillips, R. S.

    2001-01-01

    Malaria remains one of the world's worst health problems with 1.5 to 2.7 million deaths annually; these deaths are primarily among children under 5 years of age and pregnant women in sub-Saharan Africa. Of significance, more people are dying from malaria today than 30 years ago. This review considers the factors which have contributed to this gloomy picture, including those which relate to the vector, the female anopheline mosquito; to human activity such as creating new mosquito breeding sites, the impact of increased numbers of people, and how their migratory behavior can increase the incidence and spread of malaria; and the problems of drug resistance by the parasites to almost all currently available antimalarial drugs. In a selective manner, this review describes what is being done to ameliorate this situation both in terms of applying existing methods in a useful or even crucial role in control and prevention and in terms of new additions to the antimalarial armory that are being developed. Topics covered include biological control of mosquitoes, the use of insecticide-impregnated bed nets, transgenic mosquitoes manipulated for resistance to malaria parasites, old and new antimalarial drugs, drug resistance and how best to maintain the useful life of antimalarials, immunity to malaria and the search for antimalarial vaccines, and the malaria genome project and the potential benefits to accrue from it. PMID:11148010

  10. Current trends in small vocabulary speech recognition for equipment control

    NASA Astrophysics Data System (ADS)

    Doukas, Nikolaos; Bardis, Nikolaos G.

    2017-09-01

    Speech recognition systems allow human - machine communication to acquire an intuitive nature that approaches the simplicity of inter - human communication. Small vocabulary speech recognition is a subset of the overall speech recognition problem, where only a small number of words need to be recognized. Speaker independent small vocabulary recognition can find significant applications in field equipment used by military personnel. Such equipment may typically be controlled by a small number of commands that need to be given quickly and accurately, under conditions where delicate manual operations are difficult to achieve. This type of application could hence significantly benefit by the use of robust voice operated control components, as they would facilitate the interaction with their users and render it much more reliable in times of crisis. This paper presents current challenges involved in attaining efficient and robust small vocabulary speech recognition. These challenges concern feature selection, classification techniques, speaker diversity and noise effects. A state machine approach is presented that facilitates the voice guidance of different equipment in a variety of situations.

  11. Resistive wall mode feedback control in EXTRAP T2R with improved steady-state error and transient response

    NASA Astrophysics Data System (ADS)

    Brunsell, P. R.; Olofsson, K. E. J.; Frassinetti, L.; Drake, J. R.

    2007-10-01

    Experiments in the EXTRAP T2R reversed field pinch [P. R. Brunsell, H. Bergsåker, M. Cecconello et al., Plasma Phys. Control. Fusion 43, 1457 (2001)] on feedback control of m =1 resistive wall modes (RWMs) are compared with simulations using the cylindrical linear magnetohydrodynamic model, including the dynamics of the active coils and power amplifiers. Stabilization of the main RWMs (n=-11,-10,-9,-8,+5,+6) is shown using modest loop gains of the order G ˜1. However, other marginally unstable RWMs (n=-2,-1,+1,+2) driven by external field errors are only partially canceled at these gains. The experimental system stability limit is confirmed by simulations showing that the latency of the digital controller ˜50μs is degrading the system gain margin. The transient response is improved with a proportional-plus-derivative controller, and steady-state error is improved with a proportional-plus-integral controller. Suppression of all modes is obtained at high gain G ˜10 using a proportional-plus-integral-plus-derivative controller.

  12. Historical water control maps - key to understand current challenges?

    NASA Astrophysics Data System (ADS)

    Mészáros, János

    2014-05-01

    The 19th century and post-World War II decades were the main eras of water controlling in former Hungarian Kingdom and Hungary. Due to those large projects, the number and frequency of big floods were minimized but changes caused several other problems what we have to face off in the present. The main help to understand or highlight the fundamentals of those problems can be the flood control maps which, in some cases, show the original, natural riverbed and neighbouring areas of the river. There is other advantage of these maps compared to other surveys: while the main focus of the water control surveys was the river, there was sufficient time to measure the fine differences of land-use and relief in detail. Our sample area is the middle part of Tisza river and three different maps were chosen to show the changes before and after the regulations: Map of the Middle-Tisza, mapping until 1790 by János Lietzner This map is the earliest, known, topographic scale map about the river. Due to its age, the sheets are in bad state, especially their parts close to the edges and corners. A photographed, greyscale copy exists about the sheets, that was used in our research. Despite such bad conditions, it contains lots of information about the river and settlements, as well as detailed land-use before any flood regulation. New survey of Tisza river, mapping until 1932 by the Directorate of Water and Construction Because of the changes, due to time and regulation, several new surveys were ordered at the end of 19th century and between the world wars. During those new surveys, the river was re-triangulated and mapped, although cross and longitudinal section measurements also were carried out. This map clearly shows the results and changes of regulations, especially on populated areas, newly built dykes etc. but before the changes happened between 1950 and 1980. Topographic maps of the Hungarian Defence Forces - Geoinformation Services As a current, base-dataset, topographic maps

  13. Systematic errors in detecting biased agonism: Analysis of current methods and development of a new model-free approach.

    PubMed

    Onaran, H Ongun; Ambrosio, Caterina; Uğur, Özlem; Madaras Koncz, Erzsebet; Grò, Maria Cristina; Vezzi, Vanessa; Rajagopal, Sudarshan; Costa, Tommaso

    2017-03-14

    Discovering biased agonists requires a method that can reliably distinguish the bias in signalling due to unbalanced activation of diverse transduction proteins from that of differential amplification inherent to the system being studied, which invariably results from the non-linear nature of biological signalling networks and their measurement. We have systematically compared the performance of seven methods of bias diagnostics, all of which are based on the analysis of concentration-response curves of ligands according to classical receptor theory. We computed bias factors for a number of β-adrenergic agonists by comparing BRET assays of receptor-transducer interactions with Gs, Gi and arrestin. Using the same ligands, we also compared responses at signalling steps originated from the same receptor-transducer interaction, among which no biased efficacy is theoretically possible. In either case, we found a high level of false positive results and a general lack of correlation among methods. Altogether this analysis shows that all tested methods, including some of the most widely used in the literature, fail to distinguish true ligand bias from "system bias" with confidence. We also propose two novel semi quantitative methods of bias diagnostics that appear to be more robust and reliable than currently available strategies.

  14. Systematic errors in detecting biased agonism: Analysis of current methods and development of a new model-free approach

    PubMed Central

    Onaran, H. Ongun; Ambrosio, Caterina; Uğur, Özlem; Madaras Koncz, Erzsebet; Grò, Maria Cristina; Vezzi, Vanessa; Rajagopal, Sudarshan; Costa, Tommaso

    2017-01-01

    Discovering biased agonists requires a method that can reliably distinguish the bias in signalling due to unbalanced activation of diverse transduction proteins from that of differential amplification inherent to the system being studied, which invariably results from the non-linear nature of biological signalling networks and their measurement. We have systematically compared the performance of seven methods of bias diagnostics, all of which are based on the analysis of concentration-response curves of ligands according to classical receptor theory. We computed bias factors for a number of β-adrenergic agonists by comparing BRET assays of receptor-transducer interactions with Gs, Gi and arrestin. Using the same ligands, we also compared responses at signalling steps originated from the same receptor-transducer interaction, among which no biased efficacy is theoretically possible. In either case, we found a high level of false positive results and a general lack of correlation among methods. Altogether this analysis shows that all tested methods, including some of the most widely used in the literature, fail to distinguish true ligand bias from “system bias” with confidence. We also propose two novel semi quantitative methods of bias diagnostics that appear to be more robust and reliable than currently available strategies. PMID:28290478

  15. Adaptive dynamic programming for finite-horizon optimal control of discrete-time nonlinear systems with ε-error bound.

    PubMed

    Wang, Fei-Yue; Jin, Ning; Liu, Derong; Wei, Qinglai

    2011-01-01

    In this paper, we study the finite-horizon optimal control problem for discrete-time nonlinear systems using the adaptive dynamic programming (ADP) approach. The idea is to use an iterative ADP algorithm to obtain the optimal control law which makes the performance index function close to the greatest lower bound of all performance indices within an ε-error bound. The optimal number of control steps can also be obtained by the proposed ADP algorithms. A convergence analysis of the proposed ADP algorithms in terms of performance index function and control policy is made. In order to facilitate the implementation of the iterative ADP algorithms, neural networks are used for approximating the performance index function, computing the optimal control policy, and modeling the nonlinear system. Finally, two simulation examples are employed to illustrate the applicability of the proposed method.

  16. Adaptive tracking control for double-pendulum overhead cranes subject to tracking error limitation, parametric uncertainties and external disturbances

    NASA Astrophysics Data System (ADS)

    Zhang, Menghua; Ma, Xin; Rong, Xuewen; Tian, Xincheng; Li, Yibin

    2016-08-01

    In a practical application, overhead cranes are usually subjected to system parameter uncertainties, such as uncertain payload masses, cable lengths, frictions, and external disturbances, such as air resistance. Most existing crane control methods treat the payload swing as that of a single-pendulum. However, certain types of payloads and hoisting mechanisms result in double-pendulum dynamics. The double-pendulum effects will make most existing crane control methods fail to work normally. Therefore, an adaptive tracking controller for double-pendulum overhead cranes subject to parametric uncertainties and external disturbances is developed in this paper. The proposed adaptive tracking control method guarantees that the trolley tracking error is always within a prior set of boundary conditions and converges to zero rapidly. The asymptotic stability of the closed-loop system's equilibrium point is assured by Lyapunov techniques and Barbalat's Lemma. Simulation results show that the proposed adaptive tracking control method is robust with respect to system parametric uncertainties and external disturbances.

  17. Reducing current reversal time in electric motor control

    SciTech Connect

    Bredemann, Michael V

    2014-11-04

    The time required to reverse current flow in an electric motor is reduced by exploiting inductive current that persists in the motor when power is temporarily removed. Energy associated with this inductive current is used to initiate reverse current flow in the motor.

  18. Recommendations for choosing an analysis method that controls Type I error for unbalanced cluster sample designs with Gaussian outcomes.

    PubMed

    Johnson, Jacqueline L; Kreidler, Sarah M; Catellier, Diane J; Murray, David M; Muller, Keith E; Glueck, Deborah H

    2015-11-30

    We used theoretical and simulation-based approaches to study Type I error rates for one-stage and two-stage analytic methods for cluster-randomized designs. The one-stage approach uses the observed data as outcomes and accounts for within-cluster correlation using a general linear mixed model. The two-stage model uses the cluster specific means as the outcomes in a general linear univariate model. We demonstrate analytically that both one-stage and two-stage models achieve exact Type I error rates when cluster sizes are equal. With unbalanced data, an exact size α test does not exist, and Type I error inflation may occur. Via simulation, we compare the Type I error rates for four one-stage and six two-stage hypothesis testing approaches for unbalanced data. With unbalanced data, the two-stage model, weighted by the inverse of the estimated theoretical variance of the cluster means, and with variance constrained to be positive, provided the best Type I error control for studies having at least six clusters per arm. The one-stage model with Kenward-Roger degrees of freedom and unconstrained variance performed well for studies having at least 14 clusters per arm. The popular analytic method of using a one-stage model with denominator degrees of freedom appropriate for balanced data performed poorly for small sample sizes and low intracluster correlation. Because small sample sizes and low intracluster correlation are common features of cluster-randomized trials, the Kenward-Roger method is the preferred one-stage approach.

  19. Precision Quantum Control and Error-Suppressing Quantum Firmware for Robust Quantum Computing

    DTIC Science & Technology

    2014-09-24

    Biercuk, Lorenza Viola. Long-time Low-latency Quantum Memory by Dynamical Decoupling, arXiv:1206.6087v1 (06 2012) L. Viola, G. A. Paz -Silva . A...0.00 G. Paz -Silva 0.00 K. Khodjasteh 0.00 S.W. Lee 0.00 0.00 6 9 Sub Contractors (DD882) Names of Faculty Supported Names of Under Graduate students...be built by specifically taking into account the purely-dephasing nature of the error model. Working together with postdoctoral fellow Gerardo Paz

  20. Analysis of modern optimal control theory applied to plasma position and current control in TFTR

    SciTech Connect

    Firestone, M.A.

    1981-09-01

    The strong compression TFTR discharge has been segmented into regions where linear dynamics can approximate the plasma's interaction with the OH and EF power supply systems. The dynamic equations for these regions are utilized within the linear optimal control theory framework to provide active feedback gains to control the plasma position and current. Methods are developed to analyze and quantitatively evaluate the quality of control in a nonlinear, more realistic simulation. Tests are made of optimal control theory's assumptions and requirements, and the feasibility of this method for TFTR is assessed.

  1. Is a "loss of balance" a control error signal anomaly? Evidence for three-sigma failure detection in young adults.

    PubMed

    Ahmed, Alaa A; Ashton-Miller, James A

    2004-06-01

    Given that a physical definition for a loss of balance (LOB) is lacking, the hypothesis was tested that a LOB is actually a loss of effective control, as evidenced by a control error signal anomaly (CEA). A model-reference adaptive controller and failure-detection algorithm were used to represent central nervous system decision-making based on input and output signals obtained during a challenging whole-body planar balancing task. Control error was defined as the residual generated when the actual system output is compared with the predicted output of the simple first-order polynomial system model. A CEA was hypothesized to occur when the model-generated control error signal exceeded three standard deviations (3sigma) beyond the mean calculated across a 2-s trailing window. The primary hypothesis tested was that a CEA is indeed observable in 20 healthy young adults (ten women) performing the following experiment. Seated subjects were asked to balance a high-backed chair for as long as possible over its rear legs. Each subject performed ten trials. The ground reaction force under the dominant foot, which constituted the sole input to the system, was measured using a two-axis load cell. Angular acceleration of the chair represented the one degree-of-freedom system output. The results showed that the 3sigma algorithm detected a CEA in 94% of 197 trials. A secondary hypothesis was supported in that a CEA was followed in 93% of the trials by an observable compensatory response, occurring at least 100 ms later, and an average of 479 ms, later. Longer reaction times were associated with low velocities at CEA, and vice versa. It is noteworthy that this method of detecting CEA does not rely on an external positional or angular reference, or knowledge of the location of the system's center of mass.

  2. [Prevention and control of leishmaniasis vectors: current approaches].

    PubMed

    Maroli, M; Khoury, C

    2004-06-01

    Phlebotomine sandflies (Diptera: Psychodidae) are the suspected or proven vectors of Leishmania spp. in at least 88 countries, including over 40 Phlebotomus species in the Old World and a further 30 belonging to the genus Lutzomyia in the New World. In recent years, both cutaneous (CL) and zoonotic visceral leishmaniasis (ZVL) have become increasingly prevalent in urban areas, including large Latin American cities. A similar trend has been recorded in all Mediterranean areas during the last decade. Based on mathematical models, insecticidal control of sandflies appears to represent a more effective way of reducing Leishmania infantum transmission than the present strategy of culling infected dogs in Latin America as well as being more acceptable to the human population. Since man is a dead-end host of most Leishmania species, treatment of existing human cases generally does not affect transmission. Interruption of the cycle by vector control may offer a cheaper, more practical solution to treatment and improved knowledge of the alternatives available could lead to preventative measures being undertaken in more leishmaniasis foci. In this note a review of current knowledge on sandfly control is presented. Different measures to control phlebotomine sandflies, including residual spraying of dwellings and animal shelters, insecticide treated nets, application of repellents/insecticides to skin or to fabrics and impregnated dog collars are discussed. Although effective in urban areas with high concentrations of sandflies, residual spraying of insecticides is no often longer tenable in most situations. In rural areas where dwellings are more dispersed and surrounded by large, untargeted "reservoir" populations of sandflies, residual spraying of houses may be both impractical for logistic reasons and ineffective. Actually, this control measure depends on the availability of a suitable public health infrastructure, including adequate supplies of insecticide, spraying

  3. Errors in force generation and changes in controlling patterns following agonist muscle fatigue.

    PubMed

    Huang, Yi-Ming; Chang, Ya-Ju; Hsu, Miao-Ju; Chen, Chia-Ling; Fang, Chia-Ying; Wong, Alice May-Kuen

    2009-11-01

    The purpose of this study was to evaluate whether agonist muscle fatigue changed the coactivation time and the co-contraction magnitude of the agonist and antagonist muscle, and if the agonist muscle fatigue produced bias (constant error: CE) and inconsistency (variable error: VE) of the force. Subjects are 10 healthy people and one person with impaired proprioception. EMG and force for fast (0.19 +/- 0.06 s) and slow (1.20 +/- 0.44 s) targeted isometric dorsiflexions were recorded before and after fatigue of the dorsiflexors. The results revealed that the coactivation time increased after fatigue only in the slow contractions but the co-contraction magnitude did not change. The postfatigue increment of the CE was greater in the fast contractions than in the slow ones. We conclude that the postfatigue compensatory strategy can reduce the fatigue-induced bias. The change of muscles activation level after fatigue might be under the influence of the common drive. Impaired proprioception is a possible cause of the fatigue-related increase in bias and inconsistency.

  4. Action errors, error management, and learning in organizations.

    PubMed

    Frese, Michael; Keith, Nina

    2015-01-03

    Every organization is confronted with errors. Most errors are corrected easily, but some may lead to negative consequences. Organizations often focus on error prevention as a single strategy for dealing with errors. Our review suggests that error prevention needs to be supplemented by error management--an approach directed at effectively dealing with errors after they have occurred, with the goal of minimizing negative and maximizing positive error consequences (examples of the latter are learning and innovations). After defining errors and related concepts, we review research on error-related processes affected by error management (error detection, damage control). Empirical evidence on positive effects of error management in individuals and organizations is then discussed, along with emotional, motivational, cognitive, and behavioral pathways of these effects. Learning from errors is central, but like other positive consequences, learning occurs under certain circumstances--one being the development of a mind-set of acceptance of human error.

  5. Current profile control experiments in EXTRAP T2R

    NASA Astrophysics Data System (ADS)

    Brunsell, P.; Cecconello, M.; Drake, J.; Franz, P.; Malmberg, J. A.; Marrelli, L.; Martin, P.; Spizzo, G.

    2002-11-01

    EXTRAP T2R is a high aspect ratio (R=1.24 m, a = 0.183 m) reversed-field pinch device, characterised by a double, thin shell system. The simultaneous presence of many m=1, |n| > 11 tearing modes is responsible for a magnetic field turbulence, which is believed to produce the rather high energy and particle transport that is observed in this type of magnetic configuration. In this paper first results from current profile control experiments (PPCD) in a thin shell device are shown. When an edge poloidal electric field is transiently applied, an increase of the electron temperature and of the electron density is seen, which is consistent with an increase of the thermal content of the plasma. At the same time, the soft x-ray emission, measured with a newly installed miniaturised camera, shows a peaking of the profile in the core. Furthermore, the amplitudes of the m=1 tearing modes are reduced and and the rotation velocities increase during PPCD, which is also consistent with a reduction of magnetic turbulence and a heating of the plasma

  6. Central neural control of the cardiovascular system: current perspectives.

    PubMed

    Dampney, Roger A L

    2016-09-01

    This brief review, which is based on a lecture presented at the American Physiological Society Teaching Refresher Course on the Brain and Systems Control as part of the Experimental Biology meeting in 2015, aims to summarize current concepts of the principal mechanisms in the brain that regulate the autonomic outflow to the cardiovascular system. Such cardiovascular regulatory mechanisms do not operate in isolation but are closely coordinated with respiratory and other regulatory mechanisms to maintain homeostasis. The brain regulates the cardiovascular system by two general means: 1) feedforward regulation, often referred to as "central command," and 2) feedback or reflex regulation. In most situations (e.g., during exercise, defensive behavior, sleep, etc.), both of these general mechanisms contribute to overall cardiovascular homeostasis. The review first describes the mechanisms and central circuitry subserving the baroreceptor, chemoreceptor, and other reflexes that work together to regulate an appropriate level of blood pressure and blood oxygenation and then considers the brain mechanisms that defend the body against more complex environmental challenges, using dehydration and cold and heat stress as examples. The last section of the review considers the central mechanisms regulating cardiovascular function associated with different behaviors, with a specific focus on defensive behavior and exercise.

  7. Overview of current development in patient-controlled analgesia.

    PubMed

    Lindley, C

    1994-09-01

    Over the past two decades, numerous trials have assessed the safety and efficacy of patient-controlled analgesia (PCA). Advantages over conventional parenteral narcotics reported from these trials include equivalent to superior pain relief, superior patient satisfaction, decreased sedation and anxiety, faster return to normal functional status, and reduction in nursing time and hospitalization. The majority of these trials have been conducted in the postoperative patient population. In the mid to late 1980s, interest arose in applying PCA technology to the management of cancer pain. Factors that served as an impetus for the use of PCA in cancer pain included favorable reports from the postoperative setting and the often-cited statistics regarding the magnitude of the cancer pain problem. Advances in PCA technology coupled with advances in vascular access technology that allow the placement of long-term ports and catheters to facilitate intravenous, epidural, or intrathecal administration of opioid analgesics have made the applicability of PCA in ambulatory cancer patients an attractive option. The greatest breakthrough in PCA technology came with the introduction of devices making it possible to choose between intermittent (demand bolus) and continuous administration (continuous infusion) or both intermittent and continuous modes. A comparison of these types of PCA devices is described. The limitations of the literature involving PCA therapy in cancer patients make it difficult to identify optimal patient selection criteria, PCA administration schedules, drug selection and dosing, and optimal route of administration. The current status and pertinent issues related to these topics are addressed.

  8. Macroscopic strain controlled ion current in an elastomeric microchannel

    SciTech Connect

    Kuo, Chin-Chang; Nguyen, Du; Buchsbaum, Steven; Innes, Laura; Dennin, Michael; Li, Yongxue; Esser-Kahn, Aaron P.; Valdevit, Lorenzo; Sun, Lizhi; Siwy, Zuzanna

    2015-05-07

    We report on the fabrication of an ultra-high aspect ratio ionically conductive single microchannel with tunable diameter from ≈ 20 μm to fully closed. The 4 mm-long channel is fabricated in a Polydimethylsiloxane (PDMS) mold and its cross-sectional area is controlled by applying macroscopic compressive strain to the mold in a direction perpendicular to the channel length. We investigated the ionic conduction properties of the channel. For a wide range of compressive strain up to ≈ 0.27, the strain dependence of the resistance is monotonic and fully reversible. For strain > 0.27, ionic conduction suddenly shuts off and the system becomes hysteretic (whereby a finite strain reduction is required to reopen the channel). Upon unloading, the original behavior is retrieved. This reversible behavior is observed over 200 compression cycles. The cross-sectional area of the channel can be inferred from the ion current measurement, as confirmed by a Nano-Computed Tomography investigation. We show that the cross-sectional area decreases monotonically with the applied compressive strain in the reversible range, in qualitative agreement with linear elasticity theory. We find that the shut-off strain is affected by the spatial extent of the applied strain, which provides additional tunability. Our tunable channel is well-suited for multiple applications in micro/nano-fluidic devices.

  9. Dynamic phase-control of a rising sun magnetron using modulated and continuous current

    SciTech Connect

    Fernandez-Gutierrez, Sulmer; Browning, Jim; Lin, Ming-Chieh; Smithe, David N.; Watrous, Jack

    2016-01-28

    Phase-control of a magnetron is studied via simulation using a combination of a continuous current source and a modulated current source. The addressable, modulated current source is turned ON and OFF at the magnetron operating frequency in order to control the electron injection and the spoke phase. Prior simulation work using a 2D model of a Rising Sun magnetron showed that the use of 100% modulated current controlled the magnetron phase and allowed for dynamic phase control. In this work, the minimum fraction of modulated current source needed to achieve a phase control is studied. The current fractions (modulated versus continuous) were varied from 10% modulated current to 100% modulated current to study the effects on phase control. Dynamic phase-control, stability, and start up time of the device were studied for all these cases showing that with 10% modulated current and 90% continuous current, a phase shift of 180° can be achieved demonstrating dynamic phase control.

  10. Error control in the set-up of stereo camera systems for 3d animal tracking

    NASA Astrophysics Data System (ADS)

    Cavagna, A.; Creato, C.; Del Castello, L.; Giardina, I.; Melillo, S.; Parisi, L.; Viale, M.

    2015-12-01

    Three-dimensional tracking of animal systems is the key to the comprehension of collective behavior. Experimental data collected via a stereo camera system allow the reconstruction of the 3d trajectories of each individual in the group. Trajectories can then be used to compute some quantities of interest to better understand collective motion, such as velocities, distances between individuals and correlation functions. The reliability of the retrieved trajectories is strictly related to the accuracy of the 3d reconstruction. In this paper, we perform a careful analysis of the most significant errors affecting 3d reconstruction, showing how the accuracy depends on the camera system set-up and on the precision of the calibration parameters.

  11. Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

    NASA Technical Reports Server (NTRS)

    Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

    1996-01-01

    An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

  12. Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

    NASA Technical Reports Server (NTRS)

    Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

    1994-01-01

    An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

  13. Chemotherapy medication errors in a pediatric cancer treatment center: prospective characterization of error types and frequency and development of a quality improvement initiative to lower the error rate.

    PubMed

    Watts, Raymond G; Parsons, Kerry

    2013-08-01

    Chemotherapy medication errors occur in all cancer treatment programs. Such errors have potential severe consequences: either enhanced toxicity or impaired disease control. Understanding and limiting chemotherapy errors are imperative. A multi-disciplinary team developed and implemented a prospective pharmacy surveillance system of chemotherapy prescribing and administration errors from 2008 to 2011 at a Children's Oncology Group-affiliated, pediatric cancer treatment program. Every chemotherapy order was prospectively reviewed for errors at the time of order submission. All chemotherapy errors were graded using standard error severity codes. Error rates were calculated by number of patient encounters and chemotherapy doses dispensed. Process improvement was utilized to develop techniques to minimize errors with a goal of zero errors reaching the patient. Over the duration of the study, more than 20,000 chemotherapy orders were reviewed. Error rates were low (6/1,000 patient encounters and 3.9/1,000 medications dispensed) at the start of the project and reduced by 50% to 3/1,000 patient encounters and 1.8/1,000 medications dispensed during the initiative. Error types included chemotherapy dosing or prescribing errors (42% of errors), treatment roadmap errors (26%), supportive care errors (15%), timing errors (12%), and pharmacy dispensing errors (4%). Ninety-two percent of errors were intercepted before reaching the patient. No error caused identified patient harm. Efforts to lower rates were successful but have not succeeded in preventing all errors. Chemotherapy medication errors are possibly unavoidable, but can be minimized by thoughtful, multispecialty review of current policies and procedures. Pediatr Blood Cancer 2013;601320-1324. © 2013 Wiley Periodicals, Inc. Copyright © 2013 Wiley Periodicals, Inc.

  14. Force to rebalance control of HRG and suppression of its errors on the basis of FPGA.

    PubMed

    Wang, Xu; Wu, Wenqi; Luo, Bing; Fang, Zhen; Li, Yun; Jiang, Qingan

    2011-01-01

    A novel design of force to rebalance control for a hemispherical resonator gyro (HRG) based on FPGA is demonstrated in this paper. The proposed design takes advantage of the automatic gain control loop and phase lock loop configuration in the drive mode while making full use of the quadrature control loop and rebalance control loop in controlling the oscillating dynamics in the sense mode. First, the math model of HRG with inhomogeneous damping and frequency split is theoretically analyzed. In addition, the major drift mechanisms in the HRG are described and the methods that can suppress the gyro drift are mentioned. Based on the math model and drift mechanisms suppression method, four control loops are employed to realize the manipulation of the HRG by using a FPGA circuit. The reference-phase loop and amplitude control loop are used to maintain the vibration of primary mode at its natural frequency with constant amplitude. The frequency split is readily eliminated by the quadrature loop with a DC voltage feedback from the quadrature component of the node. The secondary mode response to the angle rate input is nullified by the rebalance control loop. In order to validate the effect of the digital control of HRG, experiments are carried out with a turntable. The experimental results show that the design is suitable for the control of HRG which has good linearity scale factor and bias stability.

  15. Variational quality control of hydrographic profile data with non-Gaussian errors for global ocean variational data assimilation systems

    NASA Astrophysics Data System (ADS)

    Storto, Andrea

    2016-08-01

    Quality control procedures aiming at identifying observations suspected of gross errors are an important component of modern ocean data assimilation systems. On the one hand, assimilating observations whose departures from the background state are large may result in detrimental analyses and compromise the stability of the ocean analysis system. On the other hand, the rejection of these observations may prevent the analysis from ingesting useful information, especially in areas of large variability. In this work, we investigate the quality control of in-situ hydrographic profiles through modifying the probability density function (PDF) of the observational errors and relaxing the assumption of Gaussian PDF. The new PDF is heavier-tailed than Gaussian, thus accommodating the assimilation of observations with large misfits, albeit with smaller weight given to them in the analysis. This implies a different observational term in the analysis equation, and an adaptive quality control procedure based on the innovation statistics themselves. Implemented in a global ocean variational data assimilation system at moderate horizontal resolution, the scheme proves robust and successful in assimilating more observations with respect to the simpler background quality check scheme. This leads to better skill scores against both conventional and satellite observing systems. This approach proves superior also to the case where no quality control is considered. Furthermore, the implementation considers switching on the modified cost function at the 10th iteration of the minimization so that innovation statistics are based on a good approximation of the analysis. Neglecting this strategy and turning on the variational quality control since the beginning of the minimization exhibits worse scores, qualitatively similar to those of the experiment without quality control, suggesting that in this case quality control procedures are too gentle. A specific study investigating the upper

  16. A Benchmark Study on Error Assessment and Quality Control of CCS Reads Derived from the PacBio RS.

    PubMed

    Jiao, Xiaoli; Zheng, Xin; Ma, Liang; Kutty, Geetha; Gogineni, Emile; Sun, Qiang; Sherman, Brad T; Hu, Xiaojun; Jones, Kristine; Raley, Castle; Tran, Bao; Munroe, David J; Stephens, Robert; Liang, Dun; Imamichi, Tomozumi; Kovacs, Joseph A; Lempicki, Richard A; Huang, Da Wei

    2013-07-31

    PacBio RS, a newly emerging third-generation DNA sequencing platform, is based on a real-time, single-molecule, nano-nitch sequencing technology that can generate very long reads (up to 20-kb) in contrast to the shorter reads produced by the first and second generation sequencing technologies. As a new platform, it is important to assess the sequencing error rate, as well as the quality control (QC) parameters associated with the PacBio sequence data. In this study, a mixture of 10 prior known, closely related DNA amplicons were sequenced using the PacBio RS sequencing platform. After aligning Circular Consensus Sequence (CCS) reads derived from the above sequencing experiment to the known reference sequences, we found that the median error rate was 2.5% without read QC, and improved to 1.3% with an SVM based multi-parameter QC method. In addition, a De Novo assembly was used as a downstream application to evaluate the effects of different QC approaches. This benchmark study indicates that even though CCS reads are post error-corrected it is still necessary to perform appropriate QC on CCS reads in order to produce successful downstream bioinformatics analytical results.

  17. A Benchmark Study on Error Assessment and Quality Control of CCS Reads Derived from the PacBio RS

    PubMed Central

    Jiao, Xiaoli; Zheng, Xin; Ma, Liang; Kutty, Geetha; Gogineni, Emile; Sun, Qiang; Sherman, Brad T.; Hu, Xiaojun; Jones, Kristine; Raley, Castle; Tran, Bao; Munroe, David J.; Stephens, Robert; Liang, Dun; Imamichi, Tomozumi; Kovacs, Joseph A.; Lempicki, Richard A.; Huang, Da Wei

    2013-01-01

    PacBio RS, a newly emerging third-generation DNA sequencing platform, is based on a real-time, single-molecule, nano-nitch sequencing technology that can generate very long reads (up to 20-kb) in contrast to the shorter reads produced by the first and second generation sequencing technologies. As a new platform, it is important to assess the sequencing error rate, as well as the quality control (QC) parameters associated with the PacBio sequence data. In this study, a mixture of 10 prior known, closely related DNA amplicons were sequenced using the PacBio RS sequencing platform. After aligning Circular Consensus Sequence (CCS) reads derived from the above sequencing experiment to the known reference sequences, we found that the median error rate was 2.5% without read QC, and improved to 1.3% with an SVM based multi-parameter QC method. In addition, a De Novo assembly was used as a downstream application to evaluate the effects of different QC approaches. This benchmark study indicates that even though CCS reads are post error-corrected it is still necessary to perform appropriate QC on CCS reads in order to produce successful downstream bioinformatics analytical results. PMID:24179701

  18. Doubly-Latent Models of School Contextual Effects: Integrating Multilevel and Structural Equation Approaches to Control Measurement and Sampling Error.

    PubMed

    Marsh, Herbert W; Lüdtke, Oliver; Robitzsch, Alexander; Trautwein, Ulrich; Asparouhov, Tihomir; Muthén, Bengt; Nagengast, Benjamin

    2009-11-30

    This article is a methodological-substantive synergy. Methodologically, we demonstrate latent-variable contextual models that integrate structural equation models (with multiple indicators) and multilevel models. These models simultaneously control for and unconfound measurement error due to sampling of items at the individual (L1) and group (L2) levels and sampling error due the sampling of persons in the aggregation of L1 characteristics to form L2 constructs. We consider a set of models that are latent or manifest in relation to sampling items (measurement error) and sampling of persons (sampling error) and discuss when different models might be most useful. We demonstrate the flexibility of these 4 core models by extending them to include random slopes, latent (single-level or cross-level) interactions, and latent quadratic effects. Substantively we use these models to test the big-fish-little-pond effect (BFLPE), showing that individual student levels of academic self-concept (L1-ASC) are positively associated with individual level achievement (L1-ACH) and negatively associated with school-average achievement (L2-ACH)-a finding with important policy implications for the way schools are structured. Extending tests of the BFLPE in new directions, we show that the nonlinear effects of the L1-ACH (a latent quadratic effect) and the interaction between gender and L1-ACH (an L1 × L1 latent interaction) are not significant. Although random-slope models show no significant school-to-school variation in relations between L1-ACH and L1-ASC, the negative effects of L2-ACH (the BFLPE) do vary somewhat with individual L1-ACH. We conclude with implications for diverse applications of the set of latent contextual models, including recommendations about their implementation, effect size estimates (and confidence intervals) appropriate to multilevel models, and directions for further research in contextual effect analysis.

  19. Steam generator degradation: Current mitigation strategies for controlling corrosion

    SciTech Connect

    Millett, P.

    1997-02-01

    Steam Generator degradation has caused substantial losses of power generation, resulted in large repair and maintenance costs, and contributed to significant personnel radiation exposures in Pressurized Water Reactors (PWRs) operating throughout the world. EPRI has just published the revised Steam Generator Reference Book, which reviews all of the major forms of SG degradation. This paper discusses the types of SG degradation that have been experienced with emphasis on the mitigation strategies that have been developed and implemented in the field. SG degradation is presented from a world wide perspective as all countries operating PWRs have been effected to one degree or another. The paper is written from a US. perspective where the utility industry is currently undergoing tremendous change as a result of deregulation of the electricity marketplace. Competitive pressures are causing utilities to strive to reduce Operations and Maintenance (O&M) and capital costs. SG corrosion is a major contributor to the O&M costs of PWR plants, and therefore US utilities are evaluating and implementing the most cost effective solutions to their corrosion problems. Mitigation strategies developed over the past few years reflect a trend towards plant specific solutions to SG corrosion problems. Since SG degradation is in most cases an economic problem and not a safety problem, utilities can focus their mitigation strategies on their unique financial situation. Accordingly, the focus of R&D has shifted from the development of more expensive, prescriptive solutions (e.g. reduced impurity limits) to corrosion problems to providing the utilities with a number of cost effective mitigation options (e.g. molar ratio control, boric acid treatment).

  20. Design of robust adaptive controller and feedback error learning for rehabilitation in Parkinson's disease: a simulation study.

    PubMed

    Rouhollahi, Korosh; Emadi Andani, Mehran; Karbassi, Seyed Mahdi; Izadi, Iman

    2017-02-01

    Deep brain stimulation (DBS) is an efficient therapy to control movement disorders of Parkinson's tremor. Stimulation of one area of basal ganglia (BG) by DBS with no feedback is the prevalent opinion. Reduction of additional stimulatory signal delivered to the brain is the advantage of using feedback. This results in reduction of side effects caused by the excessive stimulation intensity. In fact, the stimulatory intensity of controllers is decreased proportional to reduction of hand tremor. The objective of this study is to design a new controller structure to decrease three indicators: (i) the hand tremor; (ii) the level of delivered stimulation in disease condition; and (iii) the ratio of the level of delivered stimulation in health condition to disease condition. For this purpose, the authors offer a new closed-loop control structure to stimulate two areas of BG simultaneously. One area (STN: subthalamic nucleus) is stimulated by an adaptive controller with feedback error learning. The other area (GPi: globus pallidus internal) is stimulated by a partial state feedback (PSF) controller. Considering the three indicators, the results show that, stimulating two areas simultaneously leads to better performance compared with stimulating one area only. It is shown that both PSF and adaptive controllers are robust regarding system parameter uncertainties. In addition, a method is proposed to update the parameters of the BG model in real time. As a result, the parameters of the controllers can be updated based on the new parameters of the BG model.